Operant Schedule Research Articles

An operator scheduling model for logistics service providers

In order to enhance the performance of logistics services, managers of a distribution center (DC) or a third-party logistics service provider (LSP) have to increase the efficiency of the shop floor operations via operator performance management and operator scheduling. Traditionally, DC managers usually make decisions related to operator scheduling on the basis of their expertise without a systematic approach and, thus, inappropriate operator scheduling solutions might be generated. To solve the issues of the traditional decision-making approach for operator scheduling, this study proposes an algorithm for logistics operator scheduling on the purpose of assignment of high-efficiency operators to the corresponding logistics activities. The proposed model can be divided into two main modules, namely operator fitness determination (OFD) and logistics operator recommendation (LOR) modules. In advance of operator scheduling, the daily operation requirements are acquired to estimate the required operation time and number of operators. After that, the appropriate logistics operators for specific operations (i.e. operator fitness) can be obtained via OFD module. Based on the historical operation performance of operators and using the Hungarian method, the operator scheduling solution can be generated via LOR module. In addition to the proposed algorithm, an operator scheduling system for LSPs is developed to automatically generate suggestions for logistic operator scheduling. A real-world case is used to evaluate performance of the proposed model and system. As a whole, DC managers can systematically make decisions related to operator scheduling via the proposed model and system and effectively assign appropriate operators to the corresponding logistics activities.

The 2012 ISBER Annual Meeting & Exhibits.

The 2012 ISBER Annual Meeting & Exhibits.

Time to pay attention: attentional performance time-stamped prefrontal cholinergic activation, diurnality, and performance.

Although the impairments in cognitive performance that result from shifting or disrupting daily rhythms have been demonstrated, the neuronal mechanisms that optimize fixed-time daily performance are poorly understood. We previously demonstrated that daily practice of a sustained attention task (SAT) evokes a diurnal activity pattern in rats. Here, we report that SAT practice at a fixed time produced practice time-stamped increases in prefrontal cholinergic neurotransmission that persisted after SAT practice was terminated and in a different environment. SAT time-stamped cholinergic activation occurred regardless of whether the SAT was practiced during the light or dark phase or in constant-light conditions. In contrast, prior daily practice of an operant schedule of reinforcement, albeit generating more rewards and lever presses per session than the SAT, neither activated the cholinergic system nor affected the animals' nocturnal activity pattern. Likewise, food-restricted animals exhibited strong food anticipatory activity (FAA) and attenuated activity during the dark phase but FAA was not associated with increases in prefrontal cholinergic activity. Removal of cholinergic neurons impaired SAT performance and facilitated the reemergence of nocturnality. Shifting SAT practice away from a fixed time resulted in significantly lower performance. In conclusion, these experiments demonstrated that fixed-time, daily practice of a task assessing attention generates a precisely practice time-stamped activation of the cortical cholinergic input system. Time-stamped cholinergic activation benefits fixed-time performance and, if practiced during the light phase, contributes to a diurnal activity pattern.

Ghrelin Interacts with Neuropeptide Y Y1 and Opioid Receptors to Increase Food Reward

Ghrelin, a stomach-derived hormone, is an orexigenic peptide that was recently shown to potently increase food reward behavior. The neurochemical circuitry that links ghrelin to the mesolimbic system and food reward behavior remains unclear. Here we examined the contribution of neuropeptide Y (NPY) and opioids to ghrelin's effects on food motivation and intake. Both systems have well-established links to the mesolimbic ventral tegmental area (VTA) and reward/motivation control. NPY mediates the effect of ghrelin on food intake via activation of NPY-Y1 receptor (NPY-Y1R); their connection with respect to motivated behavior is unexplored. The role of opioids in any aspect of ghrelin's action on food-oriented behaviors is unknown. Rats were trained in a progressive ratio sucrose-induced operant schedule to measure food reward/motivation behavior. Chow intake was measured immediately after the operant test. In separate experiments, we explored the suppressive effects of a selective NPY-Y1R antagonist or opioid receptor antagonist naltrexone, injected either intracerebroventricularly or intra-VTA, on ghrelin-induced food reward behavior. The ventricular ghrelin-induced increase in sucrose-motivated behavior and chow intake were completely blocked by intracerebroventricular pretreatment with either an NPY-Y1R antagonist or naltrexone. The intra-VTA ghrelin-induced sucrose-motivated behavior was blocked only by intra-VTA naltrexone. In contrast, the intra-VTA ghrelin-stimulated chow intake was attenuated only by intra-VTA NPY-Y1 blockade. Finally, ghrelin infusion was associated with an elevated VTA μ-opioid receptor expression. Thus, we identify central NPY and opioid signaling as the necessary mediators of food intake and reward effects of ghrelin and localize these interactions to the mesolimbic VTA.

Preventing the Rebound

American health care is the costliest in the world and one of the most inefficient. The Centers for Disease Control estimate that $2.34 trillion were spent in 2008 in health care.1 Hospital care is the most expensive part of our medical system, accounting for one third of total health care expenditures (Figure 1 ). Moreover, the costs of hospital care have increased by 4.5% to 7.8% annually throughout the last decade. About 2.2 million hospital discharges in 2009 were labeled with neurological diagnoses (Table 1 ), or roughly 1 out of every 18 patients treated in hospitals.2 Hospital readmissions may have a negative impact on clinical outcomes, annulling any gains made during the previous hospitalization. Readmissions are also costly, as the average cost2 of a hospitalization for a neurological problem is $38 559. These figures represent both a challenge and an opportunity for neurohospitalists. Yet, the available medical literature offers scarce guidance regarding the main causes of clinical deterioration post-discharge. Figure 1. National health care expenditures, 2008. Table 1. Outcomes and Total Costs by Neurological Disorders, Year 2009a In the current issue of The Neurohospitalist, Nahab and colleagues survey the causes of readmissions of patients with a diagnosis of cerebrovascular disease to an academic hospital. Overall, the authors found the readmission rate to be 6.4%, of which about half were considered “avoidable” under the authors’ definition. Multivariate analysis identified length of hospital stay as the only factor associated with readmission. The principal reason for readmission was for procedures that could not be scheduled during the initial hospitalization, followed by inadequate plans for outpatient follow-up and an incomplete diagnostic workup. However, it is not entirely clear that most readmissions for a procedure are unwarranted. In many institutions, operative room schedules and preoperative workup may be difficult to arrange. Under such circumstances, it may be preferable to discharge patients and have the service in charge of the procedure to arrange for the readmission, instead of holding patients in the hospital for a workup that may prolong hospital stay for several days, particularly when patients are fully ambulatory with a Rankin score of 0. Nahab and colleagues do not clarify whether their readmissions were due to availability issues (ie, weekends or holidays) or full/inflexible operating room schedules. On the other hand, some delays are the product of traditional habits rather than evidence. For instance, many surgeons still prefer to wait several weeks after a stroke to perform a carotid endarterectomy. One of the strengths of this study is the checklist of items provided by the authors to reduce avoidable 30-day readmissions. Checklists can be easily instituted and modified in a hospital system and can improve performance and reduce errors.3 It is presently unclear whether it would be of greater benefit (and potentially more cost effective) to target some of the items to a subpopulation of patients who are high risk for readmission, for example close follow-up appointments (ie, 1 week post-discharge) for those patients with a long length of stay. This targeted intervention could be studied further in well-designed randomized controlled trials.4 As the authors note, the avoidable readmission rate of 6.4% is likely an underestimate of the true 30-day readmission rate, as this figure does not account for patients who are admitted to other hospitals. This is a particularly relevant issue for tertiary-care referral centers, which typically receive patients from a large surrounding area. This readmission rate also does not reflect post-discharge emergency room visits which tend to be expensive. Finally, it is also important to account for and explore the reasons for “unavoidable” readmissions, as the definition used in any particular study leads to wide variation in what is deemed “avoidable” versus “unavoidable.”5 In many cases, readmissions are due to medical complications (ie, aspiration pneumonitis, skin and soft tissue infections, and deep vein thrombosis [DVT]) that may have been avoidable had the proper precautions been taken. In other cases, readmission may be due to factors beyond the control of the hospital (ie, patient’s lack of adherence to the treatment plan). While controversial, using the 30-day readmission rate as a marker of quality of care is a first step in improving the transition from the hospital to the outpatient setting by identifying risk factors and assessing the impact of targeted interventions.

Slow phasic changes in nucleus accumbens dopamine release during fixed ratio acquisition: a microdialysis study

Nucleus accumbens dopamine (DA) is a critical component of the brain circuitry regulating behavioral output during reinforcement-seeking behavior. Several studies have investigated the characteristics of accumbens DA release during the performance of well-learned operant behaviors, but relatively few have focused on the initial acquisition of particular instrumental behaviors or operant schedules. The present experiments focused on the initial acquisition of operant performance on a reinforcement schedule by studying the transition from a fixed ratio 1 (FR1) schedule to another operant schedule with a higher ratio requirement (i.e. fixed ratio 5 [FR5]). Microdialysis sessions were conducted in different groups of rats that were tested on either the FR1 schedule; the first, second, or third day of FR5 training; or after weeks of FR5 training. Consistent with previous studies, well-trained rats performing on the FR5 schedule after weeks of training showed significant increases in extracellular DA in both core and shell subregions of nucleus accumbens during the behavioral session. On the first day of FR5 training, there was a substantial increase in DA release in nucleus accumbens shell (i.e. approximately 300% of baseline). In contrast, accumbens core DA release was greatest on the second day of FR5 training. In parallel experiments, DA release in core and shell subregions did not significantly increase during free consumption of the same high carbohydrate food pellets that were used in the operant experiments, despite the very high levels of food intake in experienced rats. However, in rats exposed to the high-carbohydrate food for the first time, there was a tendency for extracellular DA to show a small increase. These results demonstrate that transient increases in accumbens DA release occur during the initial acquisition of ratio performance, and suggest that core and shell subregions show different temporal patterns during acquisition of instrumental behavior.

Rimonabant Redux and Strategies to Improve the Future Outlook of CB1 Receptor Neutral‐Antagonist/Inverse‐Agonist Therapies

Rimonabant Redux and Strategies to Improve the Future Outlook of CB1 Receptor Neutral‐Antagonist/Inverse‐Agonist Therapies

Pontine and thalamic influences on fluid rewards: I. Operant responding for sucrose and corn oil

The reward strength of orosensory sucrose and corn oil was measured using fixed and progressive ratio operant schedules. Because the orosensory effects of the stimuli were of interest, Experiment 1 compared operant responses for sucrose in sham and real feeding rats. The results demonstrated that rats would work for sucrose solutions without the accompanying postingestive effects. Furthermore, the break points for high concentrations of sucrose (1.0M or 2.0M) were significantly higher in sham feeding rats than in real feeding controls. Experiment 2 investigated the role of the parabrachial nucleus (PBN) and of the thalamic orosensory area (TOA) in sucrose and corn oil reward. During free access, rats with PBN lesions (PBNx) licked significantly less sucrose solution than their controls, but both groups ingested a similar volume of corn oil emulsion. When an operant was imposed, these same PBNx rats failed to respond for sucrose and continued only modestly for corn oil. In contrast, the TOA lesioned rats (TOAx) showed no impairment in responding for sucrose or corn oil during either the free access or operant sessions. Furthermore, rats with TOA lesions demonstrated significantly higher break points for sucrose than did their controls. Together, the data imply that the PBN but not the TOA is critical for the perception of, or responding to the reward value of sucrose and corn oil.

수요자원의 등록 정보 및 참여 정보를 이용한 수요 반응 모델링

This paper proposes the registration information, the participation information for classifying demand resources participate in demand response program. Modeling demand resources from them, it evaluates values of demand resources. Specially assuming that ignore the loss in power system, they take a role as generation. This paper proposes how to evaluate demand resources’ values. Case study shows that demand response operators schedule efficiently demand response program by using index of such as the registration information the participation information of demand resource

Dispatching stream operators in parallel execution of continuous queries

Data stream is a continuous, rapid, time-varying sequence of data elements which should be processed in an online manner. These matters are under research in Data Stream Management Systems (DSMSs). Single processor DSMSs cannot satisfy data stream applications’ requirements properly. Main shortcomings are tuple latency, tuple loss, and throughput. In our previous publications, we introduced parallel execution of continuous queries to overcome these problems via performance improvement, especially in terms of tuple latency. We scheduled operators in an event-driven manner which caused system performance reduction in periods between consecutive scheduling instances. In this paper, a continuous scheduling method (dispatching) is presented to be more compatible with the continuous nature of data streams as well as queries to improve system adaptivity and performance. In a multiprocessing environment, the dispatching method forces processing nodes (logical machines) to send partially-processed tuples to next machines with minimum workload to execute the next operator on them. So, operator scheduling is done continuously and dynamically for each tuple processed by each operator. The dispatching method is described, formally presented, and its correctness is proved. Also, it is modeled in PetriNets and is evaluated via simulation. Results show that the dispatching method significantly improves system performance in terms of tuple latency, throughput, and tuple loss. Furthermore, the fluctuation of system performance parameters (against variation of system and stream characteristics) diminishes considerably and leads to high adaptivity with the underlying system.

Behavior-Level Observability Analysis for Operation Gating in Low-Power Behavioral Synthesis

Many techniques for power reduction in advanced RTL synthesis tools rely explicitly or implicitly on observability don’t-care conditions. In this article we propose a systematic approach to maximize the effectiveness of these techniques by generating power-friendly RTL descriptions in behavioral synthesis. This is done using operation gating , that is, explicitly adding a predicate to an operation based on its observability condition, so that the operation, once identified as unobservable at runtime, can be avoided using RTL power optimization techniques such as clock gating. We first introduce the concept of behavior-level observability and its approximations in the context of behavioral synthesis. We then propose an efficient procedure to compute an approximated behavior-level observability of every operation in a dataflow graph. Unlike previous techniques which work at the bit level in Boolean networks, our method is able to perform analysis at the word level, and thus avoids most computation effort with a reasonable approximation. Our algorithm exploits the observability-masking nature of some Boolean operations, as well as the select operation, and allows certain forms of other knowledge to be considered for stronger observability conditions. The approximation is proved exact for (acyclic) dataflow graphs when non-Boolean operations other than select are treated as black boxes. The behavior-level observability condition obtained by our analysis can be used to guide the operation scheduler to optimize the efficiency of operation gating. In a set of experiments on real-world designs, our method achieves an average of 33.9% reduction in total power; it outperforms a previous method by 17.1% on average and gives close-to-optimal solutions on several designs. To the best of our knowledge, this is the first time behavior-level observability analysis and optimization are performed during behavioral synthesis in a systematic manner. We believe that our idea can be applied to compiler transformations in general.

Evaluation of High-risk Patients Undergoing Spinal Surgery: A Matched Case Series

Neuromuscular (NM) spinal deformities necessitating surgical intervention present a difficult challenge to the medical community. Underlying comorbidities lead to extended hospital stays, significant complications, and social challenges in the extensive perioperative period. In response to this problem, a therapeutic algorithm, the Care Pathway for Spinal Surgery (CAPSS) has been developed at our institution to address this complex medical issue. In 1999, a multidisciplinary team developed a treatment protocol, CAPSS, that emphasized perioperative work up and operative scheduling under the direction of a dedicated care coordinator. A case series analysis was conducted to compare the surgical outcomes from before and after CAPSS implementation. Statistical analyses were performed on a carefully paired subset of NM patients (N=9). Outcome measures were hospital length of stay (LOS), pediatric intensive care unit LOS, number of days intubated, surgical estimated blood loss, postoperative curve magnitude, percent curve correction, and perioperative complications. Statistical analyses indicated that the use of CAPSS provided significant reduction in overall LOS, pediatric intensive care unit LOS, and perioperative complication rate within this patient group. CAPSS is an effective method to improve perisurgical care within the NM patients with spinal deformity necessitating operative stabilization. III-Retrospective comparative study.

Developing Crew Allocation System for the Precast Industry Using Genetic Algorithms

: The Precast Concrete Industry (PCI) is one of the major contributors to the national economy and can be categorized as labor-intensive industry. It is currently experiencing shortcomings in terms of delivery products at a competitive cost and time. This is mainly due to the inefficiencies associate with planning and scheduling of skilled operators within crew configurations. This article presents a new strategy for efficient allocation of crews of workers in the precast concrete industry using Genetic Algorithms-based simulation modeling. The aim of this study is to develop a crew allocation system that can efficiently allocate possible crews of workers to precast concrete labor-intensive repetitive processes. Genetic algorithms (GAs) have been developed to solve this type of problem. Process mapping methodologies were used to identify and document the processes involved in producing precast components. Then process simulation was used to model and simulate all these processes and GAs were tailored to be embedded with the simulation model for a better search of promising solutions. GA operators were designed to suit this type of allocation problem. “Class Interval” selection strategy was developed to give a greater opportunity for the promising chromosomes to be chosen for further investigation. Dynamic crossover and mutation operators were developed to add more randomness to the search mechanism. The results showed that adopting different combinations of crews of workers had a substantial impact on reducing the process throughput time, minimizing resources cost, and achieving the required operatives utilization.

Abstract 2611: Cisplatin negatively affects CNS progenitor cells and behavior in the adult mouse

Abstract Patients that are treated with chemotherapy exhibit long term changes in cognitive function, decreasing quality of life (Van Dam et al 1998). Although much work has been done characterizing these changes in the patient, there is little research on the possible cellular changes. Additionally, little has been done studying the effects of a single chemotherapeutic agent on cognitive function. Our laboratory has previously shown that chemotherapy, including cisplatin, decreases neural progenitor cell division and increases cell death in the mouse brain (Dietrich et al 2006; Han et al., 2008). Here, we have studied the effects of cisplatin on CNS progenitor cells and also on behavior. We found that cisplatin negatively affects progenitor cells throughout the CNS: progenitor cells migrating from the subventricular zone to the olfactory bulb, the olfactory epithelium, the dentate gyrus of the hippocampus and the corpus callosum. The subventricular zone, rostral migratory stream and olfactory bulb all showed increases in cell death and decreases in the neuroblast population. This change in progenitor cell numbers remained significant compared to vehicle control for as long as six months. In the olfactory epithelium, we found a significant decrease in proliferation of olfactory receptor neuron (ORN) progenitor cells. There was also a decrease in proliferation and an increase in cell death in the oligodendrocyte precursor cell (OPC) population of the corpus callosum and in the dentate gyrus. Using a fixed interval-60s operant schedule we examined the effects of cisplatin on performance. This schedule allows for the operant response rate to vary widely without altering the rate of reinforcement. When compared to the vehicle control, we found significant changes in response rate. These findings demonstrate that even in the absence of underlying cancer, cisplatin has adverse effects on CNS progenitor cells in multiple regions and negatively impacts behavioral outcomes. This work provides animal models of potential value in developing treatments to prevent the neurotoxic side effects of cisplatin, thus improving quality of life in recipients of this therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2611.

Initial experience of heroin use under a two-chained operant schedule influences drug-seeking behavior after one month of abstinence

To evaluate the influence of an initial heroin experience under a modified two-chained training schedule on drug-seeking behavior after a long abstinence period. Rats were trained to respond for intravenous heroin (120 microg/kg) under a heterogeneous chained schedule of reinforcement using different responses in the first and second links of the chain. Animals received low-frequency drug administration training for four days and were then subjected to one month of abstinence in their home cages. Heroin-seeking behavior induced by re-exposure to the first chain associated context or discriminative stimuli was assessed after abstinence. Almost all animals could acquire operant skills quickly under the two-chained schedule training for four days, as measured in first active response latency, travel speed and goal-box enter latency. Both first chain associated context and discriminative stimulus could reinstate heroin-seeking behavior after one month abstinence. These observations suggest that an early experience of drug use is sufficient to maintain heroin-seeking behavior even after a one month abstinence.

Operating room planning and scheduling: A literature review

This paper provides a review of recent operational research on operating room planning and scheduling. We evaluate the literature on multiple fields that are related to either the problem setting (e.g., performance measures or patient classes) or the technical features (e.g., solution technique or uncertainty incorporation). Since papers are pooled and evaluated in various ways, a diversified and detailed overview is obtained that facilitates the identification of manuscripts related to the reader’s specific interests. Throughout the literature review, we summarize the significant trends in research on operating room planning and scheduling, and we identify areas that need to be addressed in the future.

Effects of cannabinoid receptor antagonists on maintenance and reinstatement of methamphetamine self-administration in rhesus monkeys

Cannabinoid receptor antagonists have shown some promise as treatments capable of reducing abuse and relapse to a number of abused drugs. In rodents, such effects have been observed with methamphetamine self-administration. However, the effects of cannabinoid receptor antagonists on methamphetamine self-administration and relapse have not been studied in primates. In the present study, rhesus monkeys were trained to respond on a three-component operant schedule. During the first 5-min component, fixed-ratio responses were reinforced by food, during the second 90- or 180-min component fixed-ratio responses were reinforced by i.v. methamphetamine. The third component was identical to the first. There was a 5-min timeout between each component. The effects of the cannabinoid receptor antagonists AM 251 and rimonabant were tested at various doses against self-administration of 3 µg/kg/injection methamphetamine, and 1 mg/kg AM 251 and 0.3 mg/kg rimonabant were tested against the methamphetamine dose–effect function. The 1 mg/kg dose of AM 251 was also tested for its ability to alter reinstatement of extinguished self-administration responding. The cannabinoid receptor antagonist AM 251 was found to reduce methamphetamine self-administration at doses that did not affect food-reinforced responding. The cannabinoid receptor antagonist rimonabant had similar, but less robust effects. AM 251 also prevented reinstatement of extinguished methamphetamine seeking that was induced by re-exposure to a combination of methamphetamine and methamphetamine-associated cues. These results indicate that cannabinoid receptor antagonists might have therapeutic effects for the treatment of methamphetamine dependence.

Heuristics for the Operating Theatre Planning and Scheduling

In this paper, we present a two-stage approach for planning and scheduling of operating theatres. The first stage concerns the operating theatre planning problem with the objectiveof minimizing number of days required to assign all surgical cases and number of days wasted for failure to meet surgical cases deadlines. The second stage refers to the operating theatre scheduling problem with the objective of minimizing total tardiness of surgical cases and total waiting time of surgeons in operating rooms. For each problem investigated, a mathematical formulation using a mixed integer programming has been suggested. And to solve the foregoing problems, we propose firstly a set of dispatching rulebased heuristics and secondly three metaheuristics. Finally, computational experiments are presented to compare the performances of these heuristics.

Bilateral intrahippocampal NAC 61–95 effects on behavior and moderation with l-NAME treatment

Residues 61–95 of the non-amyloid component (NAC 61–95) domain of α-synuclein are responsible for the aggregation and neurotoxicity of this protein. This study evaluated the effect of N (ω)-nitro- l-arginine methyl ester ( l-NAME), a nitric oxide synthase inhibitor, on the behavior of rats bilaterally injected into the CA3 area of the dorsal hippocampus with aggregated NAC 61–95. Twenty-four male Sprague–Dawley rats were trained to respond under an alternating-lever cyclic-ratio (ALCR) operant schedule. When responding was stable, 12 rats were injected bilaterally into the CA3 area of the hippocampus with aggregated NAC 61–95 (5 μl per side; concentration 10 −4 M), the remaining 12 rats were similarly injected with sterile water (SW), six of the NAC 61–95 injected rats and six of the SW injected rats were treated for 90 days post-injections with 0.05 mg/ml l-NAME in drinking water available ad libitum. Treatment with l-NAME alleviated NAC 61–95-induced behavioral deficits, indicated through the measurement of lever switching errors and incorrect lever perseverations under the ALCR schedule, and reduced the number of activated astrocytes proximal to the injection sites.

Suitability and managerial implications of a Master Surgical Scheduling approach

Operating room (OR) planning and scheduling is a popular and challenging subject within the operational research applied to health services research (ORAHS). However, the impact in practice is very limited. The organization and culture of a hospital and the inherent characteristics of its processes impose specific implementation issues that affect the success of planning approaches. Current tactical OR planning approaches often fail to account for these issues. Master surgical scheduling (MSS) is a promising approach for hospitals to optimize resource utilization and patient flows. We discuss the pros and cons of MSS and compare MSS with centralized and decentralized planning approaches. Finally, we address various implementation issues of MSS and discuss its suitability for hospitals with different organizational foci and culture.