Basic Scheduling Research Articles

A Comparison of Due-Date Selection Rules

Abstract In sequencing and scheduling models it is usually assumed that due dates represent exogeneous information. In many practical settings, however, due dates can be discretionary, or at least negotiable. Relatively few studies have incorporated discretionary due dates, and even then the rules proposed for due-date selection have seldom been developed from normative, analytic results. In this research we return to very basic scheduling models in search of fundamental insights and relationships that suggest guidelines for due-date selection in more complicated situations. We exploit some fundamental results from scheduling theory involving the single-machine model in order to compare three basic strategies for due-date selection.

Nonexclusionary timeout: maintenance of appropriate behavior across settings.

Abstract A recent paper by Foxx and Shapiro (1978) used a nonexclusionary timeout procedure to reduce inappropriate behaviors in a mentally retarded population. The present study was designed to replicate these findings, to examine the utility of modifying the basic reinforcement schedule of the original study, and to demonstrate control across settings and maladaptive behaviors using a multiple baseline design. The subject was a 19-year-old severely retarded male, and the design consisted of implementing the program sequentially across three settings. Following initial baseline in each setting, a discriminative cue was provided to the client, and a DRO schedule was instituted. Any occurence of target disruptive behaviors resulted in removal of the discriminative cue and interruption of the reinforcement schedule. After the intervention program was implemented in each setting, inappropriate behaviors decreased to virtually zero rates of occurrence. These findings indicate that a signaled timeout can be employed successfully in more than one setting and that it can be used in conjunction with DRO reinforcement schedule. The advantages of mediating transfer of behavioral improvements with portable disciminative cues were discussed.

Another psychophysical procedure: Within-trial stimulus thresholds

Discrete trial psychophysical procedures may be combined with tracking techniques and response pattern analysis to yield stimulus thresholds within each trial. In the present study, five pigeons were trained on a concurrent signalled reinforcement procedure, but with a variable rather than fixed intensity monochromatic blue light (470 nm) within each trial. Threshold was defined as stimulus intensity at the time of a response on the signal key. Trials with known response sequences of center key—signal key responses yielded more consistent thresholds relative to trials with unknown response sequences, with typical interquartile ranges of approximately 0.1–0.2 vs 0.3–0.4 log units, respectively. The threshold distribution was shifted as a direct function of prior exposure to blue-black fluorescent illumination of 15, 60, or 240 min, with the time to recover baseline thresholds a direct function of exposure duration. Discriminative stimuli in basic operant schedules might then be modified to yield stimulus-controlled response sequences which define within-trial thresholds amenable to psychophysical manipulation.

CONSTITUENTS OF RESPONSE RATE

Response rate and the proportion of time pigeons allocated to a key-pecking activity were measured on several basic types of reinforcement schedules. Reinforcement frequency was varied within each type of basic schedule, and the effects on two constituents of response rate were noted. Propensity, the proportion of time the birds spent on a platform in front of the key, showed very consistent effects as reinforcement frequency varied: in general, it decreased when reinforcement frequency markedly decreased and it increased when reinforcement frequency increased. Speed, key pecks per unit of time spent on the platform, showed inconsistent effects when reinforcement frequency varied. Consequently, response rate showed less consistent effects than did propensity. Cumulative response records demonstrated the existence of several different types of transitions or boundary states between the key-pecking activity and other activities. The types of transitions that occurred between activities depended on both the type of reinforcement schedule and the frequency of reinforcement. The propensity data support the position that general laws of behavior can be based on temporal measures of behavior. The speed data suggest that, if a complete assessment of the dynamic properties of behavior is to be achieved, measures of behavior must incorporate the structural variations in the operant unit.

A real-time programming system.

The paper describes a Basic Operating and Scheduling System (BOSS) designed for a small computer. User programs are organised as self-contained modular 'processes' and the way in which the scheduler divides the time of the computer equally between them, while arranging for any process which has to respond to an interrupt from a peripheral device to be given the necessary priority, is described in detail. Next the procedures provided by the operating system to organise communication between processes are described, and how they are used to construct dynamically self-modifying real-time systems. Finally, the general philosophy of BOSS and applications to a multi-processor assembly are discussed.

Potential for low dose rate neutron brachytherapy for pelvic tumors

Local failure of tumor control is extremely frequent in advanced carcinomas of the cervix. Local or pelvic failure is also extremely frequent with carcinomas of the uterus, vagina, prostate or recta-sigmoid. It is believed that the use of high LET radiotherapy may overcome some of the radioresistance presumed to be due to tumor hypoxia. The use of high LET therapy for such tumors may greatly reduce the local failure rate and lead to more frequent cure of such tumors. It is known that increased local treatment success may allow distant failure to be unmasked and be manifest. We have examined boost of Cf-252 pelvic brachytherapy for advanced tumors of the cervix, endometrium and vagina. The treatments have been performed as boost implants on a basic prescription of high dose, low LET, megavoltage x-ray therapy. Three basic schedules have been studied for effectiveness: 1) neutron therapy only; 2) mixed neutron and Cs-137 implant therapy; 3) Cs-137 therapy only. We have treated Stage II-B (resistant), III and IV cervix cancers, barrel-shaped carcinomas of the cervix, given preoperatively, in medically inoperable Stage I and II endometrial cancers, slow regressor tumors and recurrent tumors. The preliminary results show that Cf-252 used in the above methods are well tolerated without major complications in early follow-up, and lead to local control at least comparable to low dose brachytherapy. The combination of external beam radiotherapy with Cf-252 neutron brachytherapy were well tolerated and led, in most cases, to tumor destruction. Cf-252 implant therapy may be a simple means of dealing with common and frequently radioresistant group of tumors.

A nuclear medicine patient/instrument scheduling model

The problem of scheduling patients and clinical instruments for each physician-requested Nuclear Medicine study, in a clinical environment, is resolved through the development of a computerized heuristic model. The study schedule was determined by minimizing such factors as elapsed instrument time, instrument idle time, and maximizing instrument utilization. The heuristic scheduling procedure was developed and evaluated for scheduling thirteen different Nuclear Medicine study types on a daily basis. The analysis showed that this heuristic can be utilized to provide a good basic schedule for use in Clinical Nuclear Medicine.

Avaliação sorológica de vacinações preventivas da difteria, do tétano e da coqueluche, efetuadas em crianças prematuras

Vinte crianças prematuras receberam, no primeiro ano de vida. vacinas que habitualmente fazem parte do esquema básico de imunizações ativas. Em amostra de soro obtida quando elas atingiram a idade de 12 meses, foram dosados os teores de antitoxina diftérica, de antitoxina tetânica e de aglutininas anti Bordetella pertussis. Valores plenamente satisfatórios de anticorpos relativos à difteria e ao tétano puderam ser encontrados e, quanto à coqueluche, nunca notaram os Autores ausência de aglutininas, mas conclusão mais decisiva não ocorreu, em virtude da falta de melhor conhecimento da cifra indicativa de proteção. O estudd em questão representa subsídio no sentido de arrefecer o temor e o cepticismo, bastante divulgados, acerca da vacinação de prematuros.

Scheduling as a Graph Transformation

The scheduling of a set of tasks, with precedence constraints and known execution times, into a set of identical processors is considered. Optimal scheduling of these tasks implies utilizing a minimum number of processors to satisfy a deadline, or finishing in minimal time using a fixed number of processors. This process can be seen as a transformation of the original graph into another graph, whose precedences do not violate the optimality constraints and has a unique basic schedule. Analysis of this transformation provides insight into the scheduling process and also into the determination of lower bounds on the number of processors and on time for optimal schedules.

Adriamycin chemotherapy--efficacy, safety, and pharmacologic basis of an intermittent single high-dosage schedule.

A study designed to correlate clinical and pharmacologic observations was undertaken in 96 patients treated with adriamycin. The basic dosage schedule was 60 mg/m2 I.V. q 3 weeks. Pharmacokinetic studies showed a prolonged plasma half-life, low urinary excretion, and undetectable levels in CSF. Patients with significantly impaired liver function had marked elevation and prolongation of plasma drug levels associated with severe toxicity unless dosage was reduced by 50-7596. Of the 82 evaluable patients, 10/25 with sarcomas, 9/31 with carcinomas, and 15/26 with hematologic malignancies have achieved complete or partial remission. An additional 22/48 have improved. Six patients with solid tumors had progressive CNS disease while responding systemically. Adriamycin can he used with relative safety and high efficacy in a dosage schedule that resulted from pharmacologic studies. Dosage reduction in patients with liver disease is essential to avoid life-threatening toxicity.

Responding under basic schedules of reinforcement in the crow.

Responding under basic schedules of reinforcement in the crow.

A behavioral analysis of an assembly line inspection task : Human Factors, 1969, 11.4, 339–352

The problem of sustained efficiency in monotonous perceptual tasks is particularly pertinent to industrial inspection. The present research has extended Holland's techniques of behavioral analysis to an industrial framework by analyzing the assembly-line inspection of products. By utilizing four basic schedules of defective product (fixed ratio, variable ratio, fixed interval, and variable interval), it was demonstrated that the detection of defectives can serve as reinforcements for observing behavior. In addition, the vigilance decrement associated with the inspection task was shown to be a function of the differential reinforcement of observing responses. The fact that a rather precise control can be exerted by the environment over the operator's observing behavior has important implications for industry. Some of these implications are discussed.

SKAI: A Knowledge Based Environment ForScheduling Traction Equipment AndPersonnel

The paper presents SKAI, a knowledge based system to schedule traction equipment and train personnel developed for the Belgian railway company SNCB. The system uses its encoded expert knowledge to support the human scheduler not only on the side-activities of the scheduling task but also on the really central problem solving aspects. SKAI's basic schedule component is fully operational, installed, and used by over twenty experts on a daily basis since July 1993. It reduces the time required to build the basic schedule with about 75%. As a result of this time optimisation the experts, working with the expert system, have been able to optimise the basic schedules with about 10%.

A behavioral analysis of an assembly line inspection task.

The problem of sustained efficiency in monotonous perceptual tasks is particularly pertinent to industrial inspection. The present research has extended Holland's techniques of behavioral analysis to an industrial framework by analyzing the assembly-line inspection of products. By utilizing four basic schedules of defective product (fixed ratio, variable ratio, fixed interval, and variable interval), it was demonstrated that the detection of defectives can serve as reinforcements for observing behavior. In addition, the vigilance decrement associated with the inspection task was shown to be a function of the differential reinforcement of observing responses. The fact that a rather precise control can be exerted by the environment over the operator's observing behavior has important implications for industry. Some of these implications are discussed.

Performance of two species of quail on basic reinforcement schedules.

Two bobwhite quail (Colinus virginianus) and two Japanese quail (Coturnix coturnix japonica) were trained to peck a response key to obtain food. In general, performance on fixed ratio 20 and variable- and fixed-interval 60-sec schedules was comparable to the response patterns of other species under these schedules.

Social Structure and Social Participation

T HIS paper reports the initial findings of a study of participation in the policy formation process at the community level carried out in Valley City I and Valley City II.' The design of the study involved the development of a scale for measuring community participation and the administering of a basic schedule to a random sample of the adult population in each community in order to identify some of the factors associated with community participation. While this study originated in an interest in social participation as it relates to the policy formation process at the local level, it subsequently became clear that the analysis of participation offers a strategic approach to the study of social structure. The immediate problem with which this paper is concerned is: Who participates to what extent in community affairs and what factors are associated with such participation? However, the more basic problem is concerned with the structural patterns of communities.

CHILD HEALTH SERVICES AND PEDIATRIC EDUCATION

The Study of Child Health Services and Pediatric Education has been reported in summary for the country as a whole and is being reported in more detail for the individual states. To summarize a summary approaches a reductio ad absurdum. But now that this momentous Study is not only completed but published, it is timely to point to a few of its most conspicuous highlights. With the permission of the Commonwealth Fund, to whom we are indebted for publication of the report, we have reproduced below the final chapter of the report itself. These few pages are in the nature of a few drops of juice squeezed out of the fruits of our labors. The full published report has been boiled down as much as has seemed consistent with an undertaking taking of this magnitude. In a first volume is to be found a general summary of child health services and pediatric education with a number of charts illustrating some of the most important findings. We have purposely avoided over-weighting this volume with heavy statistical tabulations. For those who are interested in more detail and a further analysis of the data, a second volume has been prepared containing methodology, definitions, comprehensive tabulated data, and the basic schedules used in collecting the desired information. So now, in two volumes, the report is available, prepared both for those who have general interest and for those who have more particular concern with the health of children and the training of the doctors responsible for their care—John P. Hubbard, M.D.

Experiences in the management of subacute bacterial endocarditis treated with penicillin

Experiences are related in the management of thirty-five patients with subacute bacterial endocarditis treated solely with penicillin on the wards of the Johns Hopkins Hospital. Attention is called to the difficulty of establishing a clinical diagnosis at an early stage of the disease due to the nonspecific or misleading character of the presenting symptoms, the frequent absence of classical physical findings and the prevalence of the infection in individuals with only a minimal degree of cardiac disease. The importance of early diagnosis and institution of treatment is emphasized, as continuation of infection may result in irreparable damage to the heart or kidneys or allow the occurrence of fatal emboli, although in several instances a successful therapeutic result was achieved despite a long lapse of time from the onset of disease until commencement of therapy. It is suggested that any patient with a cardiac murmur and a persistent fever should be suspected of having bacterial endocarditis until careful bacteriologic studies and clinical observations have proved otherwise. The necessity of retaining, both aerobically and anaerobically, all blood cultures for a period of not less than three weeks before they are considered sterile is emphasized as is the importance of searching for unusual organisms such as the genus Bacteroides. The course of these patients during treatment is described and the complications encountered are analyzed relative to adequacy or inadequacy of treatment received. The conclusion is reached that the two major causes of death were the underlying cardiac disease and the persistence of bacterial endocarditis. Hence, the major therapeutic concern is that adequate penicillin be given for an adequate period of time and prior to the development of unalterable cardiac abnormalities. The fact that evidence of active bacterial endocarditis was found upon autopsy examination of three patients who died while receiving treatment commonly regarded as adequate has led to critical appraisal of present criteria of therapeutic adequacy. A plan of therapeutic management is described which is thought to assure adequate therapy for the maximum number of patients. In it the penicillin dosage is based primarily upon clinical evidence of satisfactory response. Such factors as the penicillin sensitivity of bacteria, penicillin blood levels and sterilization of blood cultures have been found to have only limited value. The necessity of continuing treatment for an adequate period of time is discussed and the recommendation is made that 100,000 units of penicillin given intramuscularly every two hours for eight weeks be considered the basic and minimal treatment schedule. The pros and cons of initiating treatment before a bacteriologic diagnosis is completed are stated with the conclusion that a reasonable period of delay is justified provided the condition of the patient does not contraindicate such treatment. It is advised that blood cultures be obtained before antibiotic therapy is given to any patient with valvular or congenital heart disease who has a localized bacterial infection, lest a latent bacterial endocarditis be obscured. The value of prolonged convalescence to allow maximal healing of damaged valves is indicated. Consideration is given to the need for adequate prophylaxis against the development of subacute bacterial endocarditis not only during dental extractions but during any type of procedure which might result in transient bacteremia. The elimination of foci of infection which might serve as a reservoir of infection or reinfection is recommended. In conclusion, the immediate results of treatment are discussed and the course of surviving patients over a three to thirty-six months' period is described. An evaluation is attempted of the influence upon the ultimate outcome of certain factors, including the presence of cardiac failure before, during and after the onset of bacterial endocarditis. The final determinants of failure or success in the treatment of subacute bacterial endocarditis with penicillin appear to be the degree of cardiac damage resulting either from the bacterial infection or an underlying disease process, the severity of the embolic occurrences and the resistance of the infecting organisms.