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Saturday, October 8, 2022

Professional practice of behavior analysis

From Wikipedia, the free encyclopedia

The professional practice of behavior analysis is a domain of behavior analysis, the others being radical behaviorism, experimental analysis of behavior and applied behavior analysis. The practice of behavior analysis is the delivery of interventions to consumers that are guided by the principles of radical behaviorism and the research of both experimental and applied behavior analysis. Professional practice seeks to change specific behavior through the implementation of these principles. In many states, practicing behavior analysts hold a license, certificate, or registration. In other states, there are no laws governing their practice and, as such, the practice may be prohibited as falling under the practice definition of other mental health professionals. This is rapidly changing as behavior analysts are becoming more and more common.

The professional practice of behavior analysis is a hybrid discipline with specific influences coming from counseling, psychology, education, special education, communication disorders, physical therapy and criminal justice. As a discipline it has its own conferences, organizations, certification processes, and awards.

Defining the scope of practice

The Behavior Analysis Certification Board (BACB) defines behavior analysis as:

The field of behavior analysis grew out of the scientific study of principles of learning and behavior. It has two main branches: experimental and applied behavior analysis. The experimental analysis of behavior (EAB) is the basic science of this field and has over many decades accumulated a substantial and well-respected research literature. This literature provides the scientific foundation for applied behavior analysis (ABA), which is both an applied science that develops methods of changing behavior and a profession that provides services to meet diverse behavioral needs. Briefly, professionals in applied behavior analysis engage in the specific and comprehensive use of principles of learning, including operant and respondent learning, in order to address behavioral needs of widely varying individuals in diverse settings. Examples of these applications include: managing behavior of children in school settings; enhancing the abilities, and choices of children and adults with different kinds of disabilities; training animals; and augmenting the performance and satisfaction of employees in organizations and businesses.

Behavior analysis is based on the principles of operant and respondent conditioning. Applied behavior analysis (ABA) include the use of behavior management, behavioral engineering and behavior therapy.

Currently in the U.S. some behavior analysts at the masters level are licensed; others work with an international certification where licenses are unavailable, although this may not be allowed in some states or jurisdictions. At the doctoral level many are licensed as psychologists with Diplomate status in behavioral psychology or licensed as licensed behavior analysts. Diplomate status alone, however, does not allow one to practice in every state and each state's regulatory statute must be reviewed for the appropriateness and legality of practice.

Certification

The Behavior Analyst Certification Board (BACB) offers a technical certificate in behavior analysis. The American Psychological Association offers a diplomate (post PhD and licensed certification) in behavioral psychology.

The meaning of certification

BACB is a private non-profit organization without governmental powers to regulate behavior analytic practice. However, it does wield the power to suspend or revoke certification from those certified if they violate the strict ethical guidelines of practice. As many states are without a licensure act, this has been sufficient to deter violators as it removes their ability to vendor with the state, schools, and insurance companies under that certification. While the BACB certification means that candidates have satisfied entry-level requirements in behavior analytic training, certificants are able to practice independently within the scope of their practice and training. Thus, a BCBA (such as those who go into marketing, engineering, or other approved fields in which BCBAs work) who has never trained to work nor worked with children diagnosed with autism are discouraged to do so independently. Most health insurance companies also recognize the BCBA credential as one conferring the capability and the right to practice independently in many states (including California with the passage of SB 946 into law).

Some states still require certificants to be licensed by their respective jurisdictions for independent practice when treating behavioral health or medical problems, and a number of states including Arizona and Nevada have created a specific BCBA licensing program. Licensed certificants must operate within the scope of their license and within their areas of expertise. Where the government regulates behavior analytic services, unlicensed certificants may be supervised by a licensed professional and operate within the scope of their supervisor's license when treating disorders if that jurisdiction allows such supervision. Unlicensed certificants who provide behavior analytic training for educational or optimal performance purposes do not require licensed supervision, unless the law or precedent prohibits such practice. Where the government does not regulate the treatment of medical or psychological disorders certificants should practice in accord with the laws of their state, province, or country. All certificants must practice within their personal areas of expertise.

Licensure

The model licensing act for behavior analysts has been revised several times to reflect best practices and policy. Previous versions included provisions that would have made it in practice more difficult to obtain the necessary experiential hours for license and independent practice as a clinical psychologist.

Once the person is licensed public protection is still monitored by the licensing board as well as the BACB, both of which make sure that the person receives sufficient ongoing education, and the BACB and licensing board investigate ethical complaints. In February 2008, Indiana, Arizona, Massachusetts, Vermont, Oklahoma and other states now have legislation pending to create licensure for behavior analysts. Pennsylvania was the first state in 2008 to license behavior specialists to cover behavior analysts. Arizona, less than three weeks later, became the first state to license behavior analysts. Other states such as Nevada and Wisconsin have also passed behavior analytic licensure.

In California, after the defeat of a bill to create a license for BCBAs in 2011, the state government instead passed SB 946 which mandates that all non-governmental insurance agencies reimburse for BCBA for behavior therapy in treating autism, starting in 2012. Unlike many itger bills mandating that autism be covered by insurance, SB 946 does not currently impose a cap on services by age or funding amount – in this it is similar to other treatments such as those for heart attacks or other chronic conditions.

Service delivery models

Definitions

Behavior analytic services can be and often are delivered through various treatment modalities. These include:

  • Consultation – an indirect model in which the consultant works with the consultee to change the behavior of the client.
  • Therapy – (individual, group, or family) in which the therapist works directly with a person with some form of pathology to lessen the pathology.
  • Counseling – where the counselor works directly with a person who has problems but no pathology.
  • Coaching – in which the coach works with a person to achieve a life goal.

Primary methods

The two primary methods for delivering behavior analytic services are consultation and/or direct therapy; the former involves three parties: consultant, consultee and a client whose behavior is changed (who may or may not be present for all meetings).

Consultation can involve working with the consultee (i.e., a parent or teacher) to build a plan around the behavior of a client (i.e., a child or student), or training the consultees themselves to modify the behavior of the client. Within the domain of parent–child consultation, standard intervention includes teaching parents skills such as basic reinforcement, time-out and how to manipulate different factors to modify behavior.

Direct therapy involves the relationship of behavior analyst and client, usually one-on-one, in which the analyst is responsible for directly modifying the behavior of their client. Direct therapy is also used in schools but can also be found in group homes, in a behavior modification facility and in behavior therapy (where the focus may be on tasks such as quitting smoking, modifying behaviors for sex offenders or other types of offenders, modifying behaviors related to mood disorders) or to encourage job seeking behavior in psychiatric patients.

History of behavior models

Two older and less used models still exist for the delivery of behavior analytic services. These models were used mostly with normal or typically developing populations. These two models are the Behavioral Coaching and the Behavioral Counseling model. Both were very popular in the 1960s–1980s but have recently seen a decline in popularity, as proponents argued the merits of holding strictly to learning theory. The Association for Behavior Analysis International still retains a special interest group in behavioral counseling and coaching.

History of behavioral counseling

Behavioral counseling was very popular throughout the 1970s and at least into the early 1980s. Behavioral counseling is an active action–oriented approach that works with the typically developing population but also assists people with specific/discrete problems such as career decision making, drinking, smoking or rehabilitation after injury.

Life coaching

The behavioral coaching model is sometimes referred to as life coaching. However, like counselors and psychologists, life coaches can have varied orientations/change theories (see behavioral change theories). Behavioral life coaches operate mainly from a behavior analytic orientation. Unlike therapy, this model is applied to people who desire to achieve a specific goal such as increasing their assertiveness with others. This model is educational and is usually presented as an alternative to therapy. Coaches use behavioral techniques such as objective setting, goal setting, self-control training and behavioral activation to help clients achieve specific life goals. Behavioral coaching was sometimes used to teach job skills to people having mental retardation or head injury. In this area the model made extensive use of task analysis, direct instruction, role play, reinforcement and error correction. Often this approach employs techniques of direct instruction.

Goal of increasing reinforcement

Behavioral counseling was largely seen as a growth model that tried to increase the individuals sense of "freedom" by helping the client reduce punishment or coercion in their lives, build skills, and increase access to reinforcement. B.F. Skinner created a video discussing the processes involved and the importance of reinforcement to increase the sense of "freedom". Behavioral counseling attempts to use in-session reinforcement to improve decision-making, functional assessment of the clients problem, and behavioral interventions to reduce problem behaviors.

Social learning in behavioral counseling

Some behavioral counselors approach therapy from a social learning perspective but many held a position based on the use of behavioral psychology with a focus on the use of operant, respondent conditioning procedures. Some who did adopt a position on modeling held closer to the behavioral view of modeling as generalized imitation developed through learning processes.

Weight loss

The behavioral counseling approach became very popular in weight reduction and is on the American Psychological Association's list of evidence-based practices for weight loss. Behavioral counseling for weight loss by Richard B. Stuart led to the commercial program Weight Watchers. Recently, efforts have been made to resurrect interest in behavioral counseling as a method to effectively deliver services to normal problemed populations.

Treatment of autism

Among the available approaches to treating autism, early intensive behavioral interventions (EIBIs) have been used to promote social and language development and to reduce behaviors that interfere with learning and cognitive functioning. Such therapies also aim to increase intellectual skills and adaptive functioning. Behavior therapists are continuing to develop models of social skills.

Therapy qualifications

These are generally treatments based on applied behavior analysis (ABA) and involve intensive training of the therapists, extensive time spent in ABA therapy (20–40 hours per week) and weekly supervision by experienced clinical supervisors—known as board certified behavior analysts. ABA therapy often employs principles of overlearning to help acquire mastery and fluency of skills.

Children with autism

The ABA approach attepts to teach skills such as appropriate play, which behavioral psychologists believe to be a precursor to social interaction and engagement with the world and others. It also aims to increase appropriate social, motor, verbal, and reasoning skills as well as the ability to self-regulate. ABA therapy is used to teach behaviors to individuals with autism who may not otherwise observe these behaviors spontaneously through imitation.

In recent years the ABA approach has been criticized by members of the autistic community. Many have reported suffering from post-traumatic stress disorder as a result of being forced to comply with training procedures.

Imitation

Imitation can also be directly trained. ABA therapies teach these skills through use of behavioral observation and reinforcement or prompting to teach each step of a behavior.

Research and treatments

Some research exists to show that behavior analysis is an effective treatment for autism with many studies showing its effectiveness with persons of all ages in enhancing functioning, building skills and independence as well as improving life quality. ABA has been criticized for sometimes claiming to "cure autism". This controversy exists because behavior analysis is used to alter rates of behavior, and not the condition of "autism." Nonetheless, behavior analysis is used to treat the behaviors of many in the autistic population. While several small studies exist showing that behavior analysis holds promise in this area, the number of well-controlled studies do not rise to the level required by the American Psychological Association to hold the treatment as empirically supported in this area.

An increasing amount of research in the field of applied behavior analysis (ABA) is concerned with autism; and it is a common misconception that behavior analysts work almost exclusively with individuals with autism and that ABA is synonymous with discrete trials teaching. ABA principles can also be used with a range of typical or atypical individuals whose issues vary from developmental delays, significant behavioral problems or undesirable habits.

According to practitioners, curriculums should carefully task analyze the skill(s) needed to be learned and then ensure that proper tool skills have been taught before the skill itself is attempted to be taught. Properly performed, applied behavior analysis should be done in both artificial (table) and natural environments depending on the student's progress and needs. Once a student has mastered a skill at the table the team should move the student into a natural environment for further training and generalization of the skill.

Frequently standardized assessments such as the Assessment of Basic Language and Learning Skills (ABLLS) is used to create a baseline of the learner's functional skill set. The ABLLS breaks down the learner's strengths and weaknesses to best tailor the applied behavior analysis curriculum to them. By focusing on the exact skills that need help the teacher does not teach a skill the student knows. This can also prevent student frustration at attempting a skill for which they are not ready.

Many families have fought school districts for such programs.

Discrete trials

Discrete trials were originally used by people studying classical conditioning to demonstrate stimulus–stimulus pairing. Discrete trials are often contrasted with free operant procedures, like ones used by B.F. Skinner in learning experiments with rats and pigeons, to show how learning was influenced by rates of reinforcement. The discrete trials method was adapted as a therapy for developmentally delayed children and individuals with autism. For example, Ole Ivar Lovaas used discrete trials to teach autistic children skills including making eye contact, following simple instructions, advanced language and social skills. These discrete trials involved breaking a behavior into its most basic functional unit and presenting the units in a series.

A discrete trial usually consists of the following: the antecedent, the behavior of the student and a consequence. If the student's behavior matches what is desired the consequence is something positive: food, candy, a game, praise, etc. If the behavior was not correct the teacher offers the correct answer then repeats the trial possibly with more prompting, if needed, and may also use aversives.

There is usually an inter-trial interval that allows for a few seconds to separate each trial to allow the student to process the information, teach the student to wait and make the onset of the next trial more discrete. Discrete trials can be used to develop most skills which includes cognitive, verbal communication, play, social and self-help skills. There is a carefully laid out procedure for error correction and a problem solving model to use if the program gets stuck. Discrete trial is sometimes referred to as the Lovaas technique. Discrete trials have been helpful in the treatment of pediatric feeding problems as well as in the prevention of feeding problems.

Free operant procedures

In language training, many free operant procedures emerged in the late 1960s and early 1970s. These procedures did not try to train discrimination first, and then passively wait for generalization, but instead worked from the start on actively promoting generalization.<ref>Stokes, T.F. & Baer, D.M. (1977). "An implicit technology of generalization". Journal of Applied Behavior Analysis. 10 (2): 349–367. doi:10.1901/jaba.1977.10-349. PMC 1311194. PMID 16795561.</ref> Initially the model was referred to as incidental teaching but later was called milieu language teaching and finally natural language teaching. Peterson (2007) completed a comprehensive review of 57 studies on these training procedures. This review found that 84% of the studies of the natural language procedures looked at maintenance and 94% looked at generalization and were able to provide direct support of its occurrence as part of the training.

Other applications of applied behavior analysis

Clinical behavior analysis

Clinical Behavior Analysis highlights the application of behavior analysis to adult outpatients. Michael Dougher identified four comprehensive behavior analytic programs: Steven Hayes’ et al.'s acceptance and commitment therapy (ACT), Jacobson et al. behavioral activation (BA), Kohlenberg & Tsai's functional analytic psychotherapy, exposure therapies (i.e., Systematic desensitization), and the community reinforcement approach for treating addictions. In addition, the book highlights several recent areas of functional analysis research for common clinical problems. Many of these areas are specified in the section on behavior therapy.

Community reinforcement approach and family training

The study of behavioral factors related to addictions has a long history. The community reinforcement approach has considerable research supporting it as efficacious. Started in the 1970s by Nathan H. Azrin and his graduate student Hunt, the community reinforcement approach is a comprehensive operant program built on a functional assessment of a client's drinking behavior and the use of positive reinforcement and contingency management for nondrinking. When combined with disulfiram (an aversive procedure) community reinforcement showed remarkable effects. One component of the program that appears to be particularly strong is the non-drinking club. Applications of community reinforcement to public policy has become the recent focus of this approach.

An offshoot of the community reinforcement approach is the community reinforcement approach and family training. This program is designed to help family members of substance abusers feel empowered to engage in treatment. The rates of success have varied somewhat by study but seem to cluster around 70%. The program uses a variety of interventions based on functional assessment including a module to prevent domestic violence. Partners are trained to use positive reinforcement, various communication skills and natural consequences.

Children with disruptive disorders and parenting

With children, applied behavior analysis provides the core of the positive behavior support movement and creates the basis of Teaching-Family Model homes. Teaching-Family homes have been found to reduce recidivism for delinquent youths both while they are in the homes and after they leave. Operant procedures form the basis of behavioral parent training developed from social learning theorists. The etiological models for antisocial behavior show considerable correlation with negative reinforcement and response matching. Behavioral parent training or Parent Management Training has been very successful in the treatment of conduct disorders in children and adolescents with recent research focusing on making it more culturally sensitive. In addition, behavioral parent training has been shown to reduce corporal or abusive child discipline tactics. Behavior analysts typically adhere to a behavioral model of child development in their practice (see child development).

Recidivism

Recent studies showing that behavior analysis can reduce recidivism have led to a resurgence in behavior therapy facilities. Of particular interest has been the growing research on the Teaching-Family Model which was developed by Montrose Wolf and reduces recidivism rates. In addition, behaviorally-based early intervention programs have shown effectiveness.

Exposure therapy

Methods of counter-conditioning and respondent extinction, called exposure therapy, are often employed by many behavior therapists in the treatment of phobias, anxiety disorders such as post-traumatic stress disorder (PTSD), and addictions (cue exposure). Prolonged exposure therapy has been particularly helpful with PTSD. Several procedures to block respondent conditioning such as blocking and overshadowing are sometimes used in behavioral medicine to prevent conditioned taste aversion for patients with chemotherapy treatments. Exposure with Response Prevention (ERP) is a respondent extinction procedure often used to treat obsessive–compulsive behavior. Escape response blocking is critical for this procedure. For PTSDs exposure therapy is one of the few evidence-based techniques. Recent research suggests exposure therapy is an excellent means of alleviating both the anxiety and cognitive symptoms specific to PTSD with no additive effect for additional cognitive components. Several authors have argued that exposure by itself is necessary and sufficient to produce behavior change in reducing fear in social phobics and helping them engage more effectively with others. The Washington Post ran a story that only exposure therapy is proven for PTSD and that cognitive therapy or even drug therapy are not shown at this time to be effective.

Operant-based EEG biofeedback

Kamiya (1968) demonstrated that the alpha rhythm in humans could be operantly conditioned. He published an influential article in Psychology Today that summarized research showing subjects learn to discriminate when alpha was present or absent, and that they could use feedback to shift the dominant alpha frequency about 1 Hz. Almost half of his subjects reported experiencing a pleasant "alpha state" characterized as an "alert calmness". These reports may have contributed to the perception of alpha biofeedback as a shortcut to a meditative state. He also studied the electroencephalography (EEG) correlates of meditative states. Operant conditioning of EEG has had considerable support in many areas including attention deficit hyperactivity disorder (ADHD) and even seizure disorders. Early studies of the procedure included the treatment of seizure disorders. Luber and colleagues (1981) conducted a double blind crossover study showing that seizure activity decreased by 50% in the contingent conditioning of inhibiting brain waves as opposed to the non-contingent use. Sterman (2000) reviewed 18 studies of a total of 174 clients and found 82% of the participants had significant seizure reduction (30% less weekly seizures).

Organizational

Behavior analysis with organizations is sometimes combined with systems theory in an approach called organizational behavior management. This approach has shown success particularly in the area of behavior-based safety. Behavior safety research has lately become focused on factors that lead programs to being retained in institutions long after the designer leaves.

Educational

Direct instruction and Direct Instruction: the former representing the process and the latter a specific curriculum that highlights that process remain both current and controversial in behavior analysis. The essential features are a carefully structured fast-paced program based on teacher-directed small group instruction. One controversy that remains is that teacher creativity is admonished in the program. Even with such issues to be worked out positive gains in reading for the approach have been reported in the literature since 1968. An example of the positive gains reported by Meyer (1984) found that 34% of children in the DISTAR group were accepted to college as compared to only 17% of the control school. Current research is focused on peer delivery of the program.

School-wide positive behavior support is based on the use of behavior analytic procedures delivered in an organizational behavior management approach. School-wide behavioral support has been increasingly accepted by administrators, lawmakers and teachers as a way to improve safety in classrooms.

Curriculum-based measurement and curriculum matching is another active area of application. Curriculum-based measurement uses rate and reading performance as the primary variable in determining reading levels. The goal is to better match children to the appropriate curriculum level to remove frustration as well as to track reading performance over time to see if it is improving with intervention. This model also serves as the basis for response to intervention models.

Functional behavioral assessment was mandated in the United States for children who meet criteria under the individuals with disabilities education act. This approach has precluded many procedures for modifying and maintaining children in not just the school system, but in many cases in the regular education setting. Even children with severe behavior problems appear to be helped.

Teaching children to recruit attention has become a very important area in education. In many cases one function of children's disruptive behavior is to get attention.

Hospital settings

One area of interest in hospitals is the blocking effect—especially for conditioned taste aversion. This area of interest is considered important in the prevention of weigh loss during chemotherapy for cancer patients. Another area of growing interest in the hospital setting is the use of operant-based biofeedback with those suffering from cerebral palsy or minor spinal injuries.

Brucker's group at the University of Miami has had some success with specific operant conditioning-based biofeedback procedures to enhance functioning. While such methods are not a cure, and gains tend to be in the moderate range, they do show ability to help remaining central nervous system cells to regain some control over lost areas of functioning.

Residential treatment

Behavioral interventions have been very helpful in reducing problem behaviors in residential treatment centers. The type of residential versus mental retardation does not appear to be a factor. Behavioral interventions have been found to be successful even when medication interventions fail.

Space program

Probably one of the most interesting applications of behavior analysis in the 1960s was its contribution to the space program. Research in this area is used to train astronauts including the chimpanzees sent into space. Continued work in this area focuses on ensuring that astronauts who live in confined areas and space do not develop behavioral health problems. Most of this work was led by pioneer behaviorist Joseph V. Brady.

Consumer and professional relationships

Open communication and a supportive relationship between educational systems and families allow the student to receive a beneficial education. This pertains to typical learners as well as to individuals who need additional services. It was not until the 1960s that researchers began exploring behavior analysis as a method to educate those children who fall somewhere along the autism spectrum. Behavior analysts agree that consistency in and out of the school classroom is key in order for children with autism to maintain proper standing in school and continue to develop to their greatest potential.

Applied behavior analysts sometimes work with a team to address a person's educational or behavioral needs. Other professionals such as speech therapists, physicians and the primary caregivers are treated as key to the implementation of successful therapy in the applied behavior analysis (ABA) model. The ABA method relies on behavior principles to develop treatments appropriate for the individual. Regular meetings with professionals to discuss programming are one way to establish a successful working relationship between a family and their school. It is beneficial when a caregiver can conduct generalization procedures outside of school. In the ABA framework, developing and maintaining a structured working relationship between parents or guardians and professionals is essential to ensure consistent treatment.

Intervention goals

When working directly with clients, behavior analysts engage in a process of collaborative goal setting. Goal setting ensures that the client is already under stimulus control of the goal and is thus more likely to engage in behavior to achieve it. Behavior analytic programs are ultimately skill building, they enhance functioning, lead to higher quality of life, and build self-control. One of the most distinguishing features of behavior analysis has been its core belief that all individuals have a right to the most effective treatment for their condition, and a right to the most effective educational strategy available.

History

Applied behavior analysis is the applied side of the experimental analysis of behavior. It is based on the principles of operant and respondent conditioning and represents a major approach to behavior therapies. Its origin can be traced back to Teodoro Ayllon and Jack Michael's 1959 article "The psychiatric nurse as a behavioral engineer" as well as to initial efforts to implement teaching machines.

The research basis of ABA can be found in the theoretical work of behaviorism and radical behaviorism originating with the work of B.F. Skinner. In 1968 Baer, Wolf and Risley wrote an article that was the source of contemporary applied behavior analysis providing the criteria to judge the adequacy of research and practice in applied behavior analysis. It became the core and centerpiece behavioral engineering.

Work in respondent conditioning (what some would term classical conditioning) began with the work of Joseph Wolpe in the 1960s. It was improved by the work of Edna B Foa who did extensive research on exposure and response prevention for obsessive–compulsive disorder (OCD). In addition, she worked on exposure therapy for post-traumatic stress disorder.

Over the years most behavior analysts have existed and conducted research in many areas and University departments: behavior analysis, psychology, special education, regular education, speech–language pathology, communication disorders, school psychology, criminal justice and family life. They have belonged to many organizations including the American Psychological Association (APA) and have most often found a core intellectual home in the Association for Behavior Analysis International.

Current research

Behavior analysis remains one of the most active research areas in all of psychology, developmental disability, mental health and other studies of human behavior. Current research in behavior analysis focuses on expanding the tradition by looking at setting events, behavioral activation, the Matching law, relational frame theory, stimulus equivalences and covert conditioning as exemplified in Skinner's model of rule-governed behavior Verbal Behavior.

Experimental psychopathology

Experimental psychopathology is a behavior therapy area in which animal models are developed to simulate human pathology. For example, Wolpe studied cats to build his theory of human anxiety. This work continues today in the study of both pathology and treatment.

Controversy

Initially, applied behavior analysis used punishment such as shouting and slaps to reduce unwanted behaviors. Ethical opposition to such aversive practices caused them to fall out of favor and has stimulated development of less aversive methods, although such practices are still occasionally used, such as at the Judge Rotenberg Center. In general, aversion therapy and punishment are now less frequently used as ABA treatments due to legal restrictions. However, procedures such as odor aversion, covert sensitization and other covert conditioning procedures, based on punishment or aversion strategies, are still used effectively in the treatment of pedophiles. In addition, with some populations such as conduct disorder in children there is considerable evidence that has developed to show that all positive programs can produce change but that children will not enter into the normal range without punishment procedures. These programs have shifted to using child time-out and response–cost procedures to ensure that clients rights to effective interventions are met.

Homosexuality

In 1973 the APA removed homosexuality from its Diagnostic and Statistical Manual yet it kept "ego dystonic" homosexuality as a condition until the DSM III-R (1987). In 1974 Ole Ivar Lovaas, pioneer of the use of discrete trial teaching (DTT) to treat autism, was the second author on a journal article describing the use of ABA to reduce "feminine" behaviors and increase "masculine" behaviors of a male child in an effort to prevent adult transsexualism. Treatments designed to uphold traditional sex-role behaviors were opposed by some behavior analysts who argued that the intervention was not justified. In the late 1960s Wolpe refused to treat homosexual behavior arguing that it was easier and more productive to treat the religious guilt than the homosexuality. He instead provided assertiveness training to a homosexual client. Most behavior analysts and behavior therapists have not worked in sexual re–orientation therapy since Gerald Davison argued that the issue was not one of effectiveness but of ethics. When he wrote the paper presenting this position, Davison was president of the Association for the Advancement of Behavior Therapy, now the Association for Behavioral and Cognitive Therapies, and thus his views carried much weight. Davison argued that homosexuality is not pathological and is only a problem if it is regarded as one by society and the therapist.

Ethical practice

Punishment and aversion therapies

The use of punishment and aversion therapy procedures are a constant ethical challenge for behavior analysts. One of the original reasons for the development of the Behavior Analyst Certification Board were cases of abuse from behaviorists. Both continue to draw proponents and opposition, however, in some of the more controversial cases some middle ground has been found through legislation (see Judge Rotenberg Educational Center).

Sex offenders and recidivism

A study in 1991 showed that behavior modification was effective in sex offender treatment and covert sensitization, and it has been shown to have some effects on reducing recidivism. However Gene Able, who has done extensive research in this area, suggests that it is not as effective outside of the package which contains odor aversion, satiation therapy (masturbatory reconditioning), and various social skills training programs including empathy training. Current behavior analysis programs offer this type of comprehensive treatment approach. In addition they use a combination of functional assessment, behavior chain analysis and risk assessment to create relapse prevention strategies and to help the offender to develop better self-control.

With sex offenders who have retardation, comprehensive behavioral programming has been effective at least in the short run. This treatment included formal academic and vocational training, sex education, a unit token economy, and individual behavior therapy including sexual reconditioning. In addition it included supported competitive employment, fading of program structure, and increased community participation.

Journals

There are multiple journals which produce articles on the clinical applications of applied behavior analysis. The most popular, and widely used, of these journals is the Journal of Applied Behavior Analysis. There are many other journals dedicated to this field. Some of these include The Behavior Analyst Today, the International Journal of Behavioral Consultation and Therapy and three new journals scheduled for release in 2008: Behavior Analysis in Sports, Health, Fitness and Behavioral Medicine, the Journal of Behavior Analysis in Crime and Victim: Treatment and Prevention as well as the Association for Behavior Analysis International's Behavior Analysis in Practice.

Professional organizations

The Association for Behavior Analysis International has a special interest group for practitioner issues, behavioral counseling, and clinical behavior analysis. The Association for Behavior Analysis International has larger special interest groups for autism and behavioral medicine. The Association for Behavior Analysis International serves as the core intellectual home for behavior analysts. The Association for Behavior Analysis International sponsors multiple conferences/year, including the annual conference, annual autism conference, biannual international conference, and other conferences on specific issues such as behavioral theory and sustainability.

The Association for Behavioral and Cognitive Therapies (ABCT) also has an interest group in behavior analysis, which focuses on clinical behavior analysis. In addition, the Association for Behavioral and Cognitive Therapies has a special interest group on addictions.

Doctoral level behavior analysts who are psychologists belong to the American Psychological Association's division 25: Behavior analysis. APA offers a diplomate in behavioral psychology.

Hallmarks of aging

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Hallmarks_of_aging

The hallmarks of aging are the types of biochemical changes that occur in all organisms that experience biological aging and lead to a progressive loss of physiological integrity, impaired function and, eventually, death. They were first enumerated in a landmark paper in 2013 to conceptualize the essence of biological aging and its underlying mechanisms.

Overview

The hallmarks of aging

Over time, almost all living organisms experience a gradual and irreversible increase in senescence and an associated loss of proper function of the bodily systems. As aging is the primary risk factor for major human diseases, including cancer, diabetes, cardiovascular disorders, and neurodegenerative diseases, it is important to describe and classify the types of changes that it entails. The nine hallmarks of aging are grouped into three categories as follows:

Primary hallmarks (causes of damage)

Antagonistic hallmarks (responses to damage)

Integrative hallmarks (culprits of the phenotype)

Primary hallmarks are the primary causes of cellular damage. Antagonistic hallmarks are antagonistic or compensatory responses to the manifestation of the primary hallmarks. Integrative hallmarks are the functional result of the previous two groups of hallmarks that lead to further operational deterioration associated with aging.

The hallmarks

Each hallmark was chosen to try to fulfill the following criteria:

  1. manifests during normal aging;
  2. experimentally increasing it accelerates aging;
  3. experimentally amending it slows the normal aging process and increases healthy lifespan.

These conditions are met to different extents by each of these hallmarks. The last criterion is not present in many of the hallmarks, as science has not yet found feasible ways to amend these problems in living organisms.

Genome instability

Proper functioning of the genome is one of the most important prerequisites for the smooth functioning of a cell and the organism as a whole. Alterations in the genetic code have long been considered one of the main causal factors in aging. In multicellular organisms genome instability is central to carcinogenesis, and in humans it is also a factor in some neurodegenerative diseases such as amyotrophic lateral sclerosis or the neuromuscular disease myotonic dystrophy.

Abnormal chemical structures in the DNA are formed mainly through oxidative stress and environmental factors. A number of molecular processes work continuously to repair this damage. Unfortunately, the results are not perfect, and thus damage accumulates over time. Several review articles have shown that deficient DNA repair, allowing greater accumulation of DNA damages, causes premature aging; and that increased DNA repair facilitates greater longevity.

Telomere shortening

Human chromosomes (gray) capped with telomeres (white).

Telomeres are regions of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes. They protect the terminal regions of chromosomal DNA from progressive degradation and ensure the integrity of linear chromosomes by preventing DNA repair systems from mistaking the ends of the DNA strand for a double strand break.

Telomere shortening is associated with aging, mortality and aging-related diseases. Normal aging is associated with telomere shortening in both humans and mice, and studies on genetically modified animal models suggest causal links between telomere erosion and aging. Leonard Hayflick demonstrated that a normal human fetal cell population will divide between 40 and 60 times in cell culture before entering a senescence phase. Each time a cell undergoes mitosis, the telomeres on the ends of each chromosome shorten slightly. Cell division will cease once telomeres shorten to a critical length. This is useful when uncontrolled cell proliferation (like in cancer) needs to be stopped, but detrimental when normally functioning cells are unable to divide when necessary.

An enzyme called telomerase elongates telomeres in gametes and embryonic stem cells. Telomerase deficiency in humans has been linked to several aging-related diseases related to loss of regenerative capacity of tissues. It has also been shown that premature aging in telomerase-deficient mice is reverted when telomerase is reactivated.

Epigenomic alterations

DNA condensation - the DNA chain is wrapped around histones, which form into coils, which wrap into ever larger coils that ultimately make up the chromosome.

Out of all the genes that make up a genome, only a subset are expressed at any given time. The functioning of a genome depends both on the specific order of its nucleotides (genomic factors), and also on which sections of the DNA chain are spooled on histones and thus rendered inaccessible, and which ones are unspooled and available for transcription (epigenomic factors). Depending on the needs of the specific tissue type and environment that a given cell is in, histones can be modified to turn specific genes on or off as needed. The profile of where, when and to what extent these modifications occur (the epigenetic profile) changes with aging, turning useful genes off and unnecessary ones on, disrupting the normal functioning of the cell.

As an example, sirtuins are a type of protein deacetylases that promote the binding of DNA onto histones and thus turn unnecessary genes off. These enzymes use NAD as a cofactor. As we age, the level of NAD in our cells decreases and so does the ability of sirtuins to turn off unneeded genes at the right time. Decreasing the activity of sirtuins has been associated with accelerated aging and increasing their activity has been shown to stave off several age-related diseases.

Loss of proteostasis

Proteostasis is the homeostatic process of maintaining all the proteins necessary for the functioning of the cell in their proper shape, structure and abundance. Protein misfolding, oxidation, abnormal cleavage or undesired post-translational modification can create dysfunctional or even toxic proteins or protein aggregates that hinder the normal functioning of the cell. Though these proteins are continually removed and recycled, formation of damaged or aggregated proteins increases with age, leading to a gradual loss of proteostasis. This can be slowed or suppressed by caloric restriction or by administration of rapamycin, both through inhibiting the mTOR pathway.

Deregulated nutrient sensing

Nutrient sensing is a cell's ability to recognize, and respond to, changes in the concentration of macronutrients such as glucose, fatty acids and amino acids. In times of abundance, anabolism is induced through various pathways, the most well-studied among them the mTOR pathway. When energy and nutrients are scarce, the AMPK receptor senses this and switches off mTOR to conserve resources.

In a growing organism, growth and cell proliferation are important and thus mTOR is upregulated. In a fully grown organism, mTOR-activating signals naturally decline during aging. It has been found that forcibly overactivating these pathways in grown mice leads to accelerated aging and increased incidence of cancer. mTOR inhibition methods like dietary restriction or administering rapamycin have been shown to be one of the most robust methods of increasing lifespan in worms, flies and mice.

Mitochondrial dysfunction

Mitochondrion

The mitochondrion is the powerhouse of the cell. Different human cells contain from 20 to 30 up to several thousand mitochondria, each one converting carbon (in the form of acetyl-CoA) and oxygen into energy (in the form of ATP) and carbon dioxide.

During aging, the efficiency of mitochondria tends to decrease. The reasons for this are still quite unclear, but several mechanisms are suspected - reduced biogenesis, accumulation of damage and mutations in mitochondrial DNA, oxidation of mitochondrial proteins, and defective quality control by mitophagy.

Dysfunctional mitochondria contribute to aging through interfering with intracellular signaling and triggering inflammatory reactions.

Cellular senescence

Under certain conditions, a cell will exit the cell cycle without dying, instead becoming dormant and ceasing its normal function. This is called cellular senescence. Senescence can be induced by several factors, including telomere shortening, DNA damage and stress. Since the immune system is programmed to seek out and eliminate senescent cells, it might be that senescence is one way for the body to rid itself of cells damaged beyond repair.

The links between cell senescence and aging are several:

Stem cell exhaustion

Stem cells are undifferentiated or partially differentiated cells that can proliferate indefinitely. For the first few days after fertilization, the embryo consists almost entirely of stem cells. As the fetus grows, the cells multiply, differentiate and assume their appropriate function within the organism. In adults, stem cells are mostly located in areas that undergo gradual wear (intestine, lung, mucosa, skin) or need continuous replenishment (red blood cells, immune cells, sperm cells, hair follicles).

Loss of regenerative ability is one of the most obvious consequences of aging. This is largely because the proportion of stem cells and the speed of their division gradually lowers over time. It has been found that stem cell rejuvenation can reverse some of the effects of aging at the organismal level.

Altered intercellular communication

Different tissues and the cells they consist of need to orchestrate their work in a tightly controlled manner so that the organism as a whole can function. One of the main ways this is achieved is through excreting signal molecules into the blood where they make their way to other tissues, affecting their behavior. The profile of these molecules changes as we age.

One of the most prominent changes in cell signaling biomarkers is "inflammaging", the development of a chronic low-grade inflammation throughout the body with advanced age. The normal role of inflammation is to recruit the body's immune system and repair mechanisms to a specific damaged area for as long as the damage and threat are present. The constant presence of inflammation markers throughout the body wears out the immune system and damages healthy tissue.

It's also been found that senescent cells excrete a specific set of molecules called the SASP (Senescence-Associated Secretory Phenotype) which induce senescence in neighboring cells. Conversely, lifespan-extending manipulations targeting one tissue can slow the aging process in other tissues as well.

Alternative conceptual models

The Seven Pillars of Aging Model

Other scientists have defined a slightly different conceptual model for aging, called 'The Seven Pillars of Aging', in which just three of the 'hallmarks of aging' are included (stem cells and regeneration, proteostasis, epigenetics). The seven pillars model highlights the interconnectedness between all of the seven pillars which is not highlighted in the nine hallmarks of aging model.

Mass production

From Wikipedia, the free encyclopedia

Mass production, also known as flow production or continuous production, is the production of substantial amounts of standardized products in a constant flow, including and especially on assembly lines. Together with job production and batch production, it is one of the three main production methods.

The term mass production was popularized by a 1926 article in the Encyclopædia Britannica supplement that was written based on correspondence with Ford Motor Company. The New York Times used the term in the title of an article that appeared before publication of the Britannica article.

The concepts of mass production are applied to various kinds of products: from fluids and particulates handled in bulk (food, fuel, chemicals and mined minerals), to parts and assemblies of parts (household appliances and automobiles).

Some mass production techniques, such as standardized sizes and production lines, predate the Industrial Revolution by many centuries; however, it was not until the introduction of machine tools and techniques to produce interchangeable parts were developed in the mid-19th century that modern mass production was possible.

Overview

Mass production involves making many copies of products, very quickly, using assembly line techniques to send partially complete products to workers who each work on an individual step, rather than having a worker work on a whole product from start to finish.

Mass production of fluid matter typically involves pipes with centrifugal pumps or screw conveyors (augers) to transfer raw materials or partially complete products between vessels. Fluid flow processes such as oil refining and bulk materials such as wood chips and pulp are automated using a system of process control which uses various instruments to measure variables such as temperature, pressure, volumetric and level, providing feedback.

Bulk materials such as coal, ores, grains and wood chips are handled by belt, chain, slat, pneumatic or screw conveyors, bucket elevators and mobile equipment such as front-end loaders. Materials on pallets are handled with forklifts. Also used for handling heavy items like reels of paper, steel or machinery are electric overhead cranes, sometimes called bridge cranes because they span large factory bays.

Mass production is capital-intensive and energy-intensive, for it uses a high proportion of machinery and energy in relation to workers. It is also usually automated while total expenditure per unit of product is decreased. However, the machinery that is needed to set up a mass production line (such as robots and machine presses) is so expensive that in order to attain profits there must be some assurance that the product is to be successful to.

One of the descriptions of mass production is that "the skill is built into the tool", which means that the worker using the tool may not need the skill. For example, in the 19th or early 20th century, this could be expressed as "the craftsmanship is in the workbench itself" (not the training of the worker). Rather than having a skilled worker measure every dimension of each part of the product against the plans or the other parts as it is being formed, there were jigs ready at hand to ensure that the part was made to fit this set-up. It had already been checked that the finished part would be to specifications to fit all the other finished parts—and it would be made more quickly, with no time spent on finishing the parts to fit one another. Later, once computerized control came about (for example, CNC), jigs were obviated, but it remained true that the skill (or knowledge) was built into the tool (or process, or documentation) rather than residing in the worker's head. This is the specialized capital required for mass production; each workbench and set of tools (or each CNC cell, or each fractionating column) is different (fine-tuned to its task).

History

Pre-industrial

Sometimes production in series has obvious benefits, as is the case with this 5-sickle casting mold from the Bronze Age on show at a museum in Yekaterinburg, Russia.
 
This woodcut from 1568 shows the left printer removing a page from the press while the one at right inks the text-blocks. Such a duo could reach 14,000 hand movements per working day, printing around 3,600 pages in the process.

Standardized parts and sizes and factory production techniques were developed in pre-industrial times; before the invention of machine tools the manufacture of precision parts, especially metal ones, was very labor-intensive.

Crossbows made with bronze parts were produced in China during the Warring States period. The Qin Emperor unified China at least in part by equipping large armies with these weapons, which were equipped with a sophisticated trigger mechanism made of interchangeable parts. The Terracotta Army guarding the Emperor's necropolis is also believed to have been created through the use of standardized molds on an assembly line.

In ancient Carthage, ships of war were mass-produced on a large scale at a moderate cost, allowing them to efficiently maintain their control of the Mediterranean. Many centuries later, the Republic of Venice would follow Carthage in producing ships with prefabricated parts on an assembly line: the Venetian Arsenal produced nearly one ship every day in what was effectively the world's first factory, which at its height employed 16,000 people.

The invention of movable type has allowed for documents such as books to be mass produced. The first movable type system was invented in China by Bi Sheng, during the reign of the Song Dynasty, where it was used to, among other things, issue paper money. The oldest extant book produced using metal type is the Jikji, printed in Korea in the year 1377. Johannes Gutenberg, through his invention of the printing press and production of the Gutenberg Bible, introduced movable type to Europe. Through this introduction, mass production in the European publishing industry was made commonplace, leading to a democratization of knowledge, increased literacy and education, and the beginnings of modern science.

Jean-Baptiste de Gribeauval, a French artillery engineer, introduced the standardization of cannon design in the mid-18th century. He developed a 6-inch (150 mm) field howitzer whose gun barrel, carriage assembly and ammunition specifications were made uniform for all French cannons. The standardized interchangeable parts of these cannons down to the nuts, bolts and screws made their mass production and repair easier than before.

Industrial

In the Industrial Revolution, simple mass production techniques were used at the Portsmouth Block Mills in England to make ships' pulley blocks for the Royal Navy in the Napoleonic Wars. It was achieved in 1803 by Marc Isambard Brunel in cooperation with Henry Maudslay under the management of Sir Samuel Bentham. The first unmistakable examples of manufacturing operations carefully designed to reduce production costs by specialized labour and the use of machines appeared in the 18th century in England.

A pulley block for rigging on a sailing ship. By 1808, annual production in Portsmouth reached 130,000 blocks.

The Navy was in a state of expansion that required 100,000 pulley blocks to be manufactured a year. Bentham had already achieved remarkable efficiency at the docks by introducing power-driven machinery and reorganising the dockyard system. Brunel, a pioneering engineer, and Maudslay, a pioneer of machine tool technology who had developed the first industrially practical screw-cutting lathe in 1800 which standardized screw thread sizes for the first time which in turn allowed the application of interchangeable parts, collaborated on plans to manufacture block-making machinery. By 1805, the dockyard had been fully updated with the revolutionary, purpose-built machinery at a time when products were still built individually with different components. A total of 45 machines were required to perform 22 processes on the blocks, which could be made into one of three possible sizes. The machines were almost entirely made of metal thus improving their accuracy and durability. The machines would make markings and indentations on the blocks to ensure alignment throughout the process. One of the many advantages of this new method was the increase in labour productivity due to the less labour-intensive requirements of managing the machinery. Richard Beamish, assistant to Brunel's son and engineer, Isambard Kingdom Brunel, wrote:

So that ten men, by the aid of this machinery, can accomplish with uniformity, celerity and ease, what formerly required the uncertain labour of one hundred and ten.

By 1808, annual production from the 45 machines had reached 130,000 blocks and some of the equipment was still in operation as late as the mid-twentieth century. Mass production techniques were also used to rather limited extent to make clocks and watches, and to make small arms, though parts were usually non-interchangeable. Though produced on a very small scale, Crimean War gunboat engines designed and assembled by John Penn of Greenwich are recorded as the first instance of the application of mass production techniques (though not necessarily the assembly-line method) to marine engineering. In filling an Admiralty order for 90 sets to his high-pressure and high-revolution horizontal trunk engine design, Penn produced them all in 90 days. He also used Whitworth Standard threads throughout. Prerequisites for the wide use of mass production were interchangeable parts, machine tools and power, especially in the form of electricity.

Some of the organizational management concepts needed to create 20th-century mass production, such as scientific management, had been pioneered by other engineers (most of whom are not famous, but Frederick Winslow Taylor is one of the well-known ones), whose work would later be synthesized into fields such as industrial engineering, manufacturing engineering, operations research, and management consultancy. Although after leaving the Henry Ford Company which was rebranded as Cadillac and later was awarded the Dewar Trophy in 1908 for creating interchangeable mass-produced precision engine parts, Henry Ford downplayed the role of Taylorism in the development of mass production at his company. However, Ford management performed time studies and experiments to mechanize their factory processes, focusing on minimizing worker movements. The difference is that while Taylor focused mostly on efficiency of the worker, Ford also substituted for labor by using machines, thoughtfully arranged, wherever possible.

In 1807, Eli Terry was hired to produce 4,000 wooden movement clocks in the Porter Contract. At this time, the annual yield for wooden clocks did not exceed a few dozen on average. Terry developed a Milling machine in 1795, in which he perfected Interchangeable parts. In 1807, Terry developed a spindle cutting machine, which could produce multiple parts at the same time. Terry hired Silas Hoadley and Seth Thomas to work the Assembly line at the facilities. The Porter Contract was the first contract which called for mass production of clock movements in history. In 1815, Terry began mass-producing the first shelf clock. Chauncey Jerome, an apprentice of Eli Terry mass-produced up to 20,000 brass clocks annually in 1840 when he invented the cheap 30-hour OG clock.

The United States Department of War sponsored the development of interchangeable parts for guns produced at the arsenals at Springfield, Massachusetts and Harpers Ferry, Virginia (now West Virginia) in the early decades of the 19th century, finally achieving reliable interchangeability by about 1850. This period coincided with the development of machine tools, with the armories designing and building many of their own. Some of the methods employed were a system of gauges for checking dimensions of the various parts and jigs and fixtures for guiding the machine tools and properly holding and aligning the work pieces. This system came to be known as armory practice or the American system of manufacturing, which spread throughout New England aided by skilled mechanics from the armories who were instrumental in transferring the technology to the sewing machines manufacturers and other industries such as machine tools, harvesting machines and bicycles. Singer Manufacturing Co., at one time the largest sewing machine manufacturer, did not achieve interchangeable parts until the late 1880s, around the same time Cyrus McCormick adopted modern manufacturing practices in making harvesting machines.

Mass production of Consolidated B-32 Dominator airplanes at Consolidated Aircraft Plant No. 4, near Fort Worth, Texas, during World War II.

During World War II, The United States mass-produced many vehicles and weapons, such as ships (i.e. Liberty Ships, Higgins boats ), aircraft (i.e. North American P-51 Mustang, Consolidated B-24 Liberator, Boeing B-29 Superfortress), jeeps (i.e. Willys MB), trucks, tanks (i.e. M4 Sherman) and M2 Browning and M1919 Browning machine guns. Many vehicles, transported by ships have been shipped in parts and later assembled on-site.

For the ongoing energy transition, many wind turbine components and solar panels are being mass-produced. Wind turbines and solar panels are being used in respectively wind farms and solar farms.

In addition, in the ongoing climate change mitigation, large-scale carbon sequestration (through reforestation, blue carbon restoration, etc) has been proposed. Some projects (such as the Trillion Tree Campaign) involve planting a very large amount of trees. In order to speed up such efforts, fast propagation of trees may be useful. Some automated machines have been produced to allow for fast (vegetative) plant propagation. Also, for some plants that help to sequester carbon (such as seagrass), techniques have been developed to help speed up the process.

Mass production benefited from the development of materials such as inexpensive steel, high strength steel and plastics. Machining of metals was greatly enhanced with high-speed steel and later very hard materials such as tungsten carbide for cutting edges. Fabrication using steel components was aided by the development of electric welding and stamped steel parts, both which appeared in industry in about 1890. Plastics such as polyethylene, polystyrene and polyvinyl chloride (PVC) can be easily formed into shapes by extrusion, blow molding or injection molding, resulting in very low cost manufacture of consumer products, plastic piping, containers and parts.

An influential article that helped to frame and popularize the 20th century's definition of mass production appeared in a 1926 Encyclopædia Britannica supplement. The article was written based on correspondence with Ford Motor Company and is sometimes credited as the first use of the term.

Factory electrification

Electrification of factories began very gradually in the 1890s after the introduction of a practical DC motor by Frank J. Sprague and accelerated after the AC motor was developed by Galileo Ferraris, Nikola Tesla and Westinghouse, Mikhail Dolivo-Dobrovolsky and others. Electrification of factories was fastest between 1900 and 1930, aided by the establishment of electric utilities with central stations and the lowering of electricity prices from 1914 to 1917.

Electric motors were several times more efficient than small steam engines because central station generation were more efficient than small steam engines and because line shafts and belts had high friction losses. Electric motors also allowed more flexibility in manufacturing and required less maintenance than line shafts and belts. Many factories saw a 30% increase in output simply from changing over to electric motors.

Electrification enabled modern mass production, as with Thomas Edison's iron ore processing plant (about 1893) that could process 20,000 tons of ore per day with two shifts, each of five men. At that time it was still common to handle bulk materials with shovels, wheelbarrows and small narrow-gauge rail cars, and for comparison, a canal digger in previous decades typically handled five tons per 12-hour day.

The biggest impact of early mass production was in manufacturing everyday items, such as at the Ball Brothers Glass Manufacturing Company, which electrified its mason jar plant in Muncie, Indiana, U.S., around 1900. The new automated process used glass-blowing machines to replace 210 craftsman glass blowers and helpers. A small electric truck was used to handle 150 dozen bottles at a time where previously a hand truck would carry six dozen. Electric mixers replaced men with shovels handling sand and other ingredients that were fed into the glass furnace. An electric overhead crane replaced 36 day laborers for moving heavy loads across the factory.

According to Henry Ford:

The provision of a whole new system of electric generation emancipated industry from the leather belt and line shaft, for it eventually became possible to provide each tool with its own electric motor. This may seem only a detail of minor importance. In fact, modern industry could not be carried out with the belt and line shaft for a number of reasons. The motor enabled machinery to be arranged in the order of the work, and that alone has probably doubled the efficiency of industry, for it has cut out a tremendous amount of useless handling and hauling. The belt and line shaft were also tremendously wasteful – so wasteful indeed that no factory could be really large, for even the longest line shaft was small according to modern requirements. Also high speed tools were impossible under the old conditions – neither the pulleys nor the belts could stand modern speeds. Without high speed tools and the finer steels which they brought about, there could be nothing of what we call modern industry.

The assembly plant of the Bell Aircraft Corporation in 1944. Note parts of overhead crane at both sides of photo near top.

Mass production was popularized in the late 1910s and 1920s by Henry Ford's Ford Motor Company, which introduced electric motors to the then-well-known technique of chain or sequential production. Ford also bought or designed and built special purpose machine tools and fixtures such as multiple spindle drill presses that could drill every hole on one side of an engine block in one operation and a multiple head milling machine that could simultaneously machine 15 engine blocks held on a single fixture. All of these machine tools were arranged systematically in the production flow and some had special carriages for rolling heavy items into machining position. Production of the Ford Model T used 32,000 machine tools.

Buildings

The process of prefabrication, wherein parts are created separately from the finished product, is at the core of all mass-produced construction. Early examples include movable structures reportedly utilized by Akbar the Great, and the chattel houses built by emancipated slaves on Barbados. The Nissen hut, first used by the British during World War I, married prefabrication and mass production in a way that suited the needs of the military. The simple structures, which cost little and could be erected in just a couple of hours, were highly successful: over 100,000 Nissen huts were produced during World War I alone, and they would go on to serve in other conflicts and inspire a number of similar designs.

Following World War II, in the United States, William Levitt pioneered the building of standardized tract houses in 56 different locations around the country. These communities were dubbed Levittowns, and they were able to be constructed quickly and cheaply through the leveraging of economies of scale, as well as the specialization of construction tasks in a process akin to an assembly line. This era also saw the invention of the mobile home, a small prefabricated house that can be transported cheaply on a truck bed.

In the modern industrialization of construction, mass production is often used for prefabrication of house components.

The use of assembly lines

Ford assembly line, 1913. The magneto assembly line was the first.

Mass production systems for items made of numerous parts are usually organized into assembly lines. The assemblies pass by on a conveyor, or if they are heavy, hung from an overhead crane or monorail.

In a factory for a complex product, rather than one assembly line, there may be many auxiliary assembly lines feeding sub-assemblies (i.e. car engines or seats) to a backbone "main" assembly line. A diagram of a typical mass-production factory looks more like the skeleton of a fish than a single line.

Vertical integration

Vertical integration is a business practice that involves gaining complete control over a product's production, from raw materials to final assembly.

In the age of mass production, this caused shipping and trade problems in that shipping systems were unable to transport huge volumes of finished automobiles (in Henry Ford's case) without causing damage, and also government policies imposed trade barriers on finished units.

Ford built the Ford River Rouge Complex with the idea of making the company's own iron and steel in the same large factory site where parts and car assembly took place. River Rouge also generated its own electricity.

Upstream vertical integration, such as to raw materials, is away from leading technology toward mature, low-return industries. Most companies chose to focus on their core business rather than vertical integration. This included buying parts from outside suppliers, who could often produce them as cheaply or cheaper.

Standard Oil, the major oil company in the 19th century, was vertically integrated partly because there was no demand for unrefined crude oil, but kerosene and some other products were in great demand. The other reason was that Standard Oil monopolized the oil industry. The major oil companies were, and many still are, vertically integrated, from production to refining and with their own retail stations, although some sold off their retail operations. Some oil companies also have chemical divisions.

Lumber and paper companies at one time owned most of their timber lands and sold some finished products such as corrugated boxes. The tendency has been to divest of timber lands to raise cash and to avoid property taxes.

Advantages and disadvantages

The economies of mass production come from several sources. The primary cause is a reduction of non-productive effort of all types. In craft production, the craftsman must bustle about a shop, getting parts and assembling them. He must locate and use many tools many times for varying tasks. In mass production, each worker repeats one or a few related tasks that use the same tool to perform identical or near-identical operations on a stream of products. The exact tool and parts are always at hand, having been moved down the assembly line consecutively. The worker spends little or no time retrieving and/or preparing materials and tools, and so the time taken to manufacture a product using mass production is shorter than when using traditional methods.

The probability of human error and variation is also reduced, as tasks are predominantly carried out by machinery; error in operating such machinery has more far-reaching consequences. A reduction in labour costs, as well as an increased rate of production, enables a company to produce a larger quantity of one product at a lower cost than using traditional, non-linear methods.

However, mass production is inflexible because it is difficult to alter a design or production process after a production line is implemented. Also, all products produced on one production line will be identical or very similar, and introducing variety to satisfy individual tastes is not easy. However, some variety can be achieved by applying different finishes and decorations at the end of the production line if necessary. The starter cost for the machinery can be expensive so the producer must be sure it sells or the producers will lose a lot of money.

The Ford Model T produced tremendous affordable output but was not very good at responding to demand for variety, customization, or design changes. As a consequence Ford eventually lost market share to General Motors, who introduced annual model changes, more accessories and a choice of colors.

With each passing decade, engineers have found ways to increase the flexibility of mass production systems, driving down the lead times on new product development and allowing greater customization and variety of products.

Compared with other production methods, mass production can create new occupational hazards for workers. This is partly due to the need for workers to operate heavy machinery while also working close together with many other workers. Preventative safety measures, such as fire drills, as well as special training is therefore necessary to minimise the occurrence of industrial accidents.

Socioeconomic impacts

In the 1830s, French political thinker and historian Alexis de Tocqueville identified one of the key characteristics of America that would later make it so amenable to the development of mass production: the homogeneous consumer base. De Tocqueville wrote in his Democracy in America (1835) that "The absence in the United States of those vast accumulations of wealth which favor the expenditures of large sums on articles of mere luxury... impact to the productions of American industry a character distinct from that of other countries' industries. [Production is geared toward] articles suited to the wants of the whole people".

Mass production improved productivity, which was a contributing factor to economic growth and the decline in work week hours, alongside other factors such as transportation infrastructures (canals, railroads and highways) and agricultural mechanization. These factors caused the typical work week to decline from 70 hours in the early 19th century to 60 hours late in the century, then to 50 hours in the early 20th century and finally to 40 hours in the mid-1930s.

Mass production permitted great increases in total production. Using a European crafts system into the late 19th century it was difficult to meet demand for products such as sewing machines and animal powered mechanical harvesters. By the late 1920s many previously scarce goods were in good supply. One economist has argued that this constituted "overproduction" and contributed to high unemployment during the Great Depression. Say's law denies the possibility of general overproduction and for this reason classical economists deny that it had any role in the Great Depression.

Mass production allowed the evolution of consumerism by lowering the unit cost of many goods used.

Introduction to entropy

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Introduct...