GRASP/VND and multi-start evolutionary local search for the single truck and trailer routing problem with satellite depots

In the single truck and trailer routing problem with satellite depots (STTRPSD) a vehicle composed of a truck with a detachable trailer serves the demand of a set of customers reachable only by the truck without the trailer. This accessibility constraint implies the selection of locations to park the trailer before performing the trips to the customers. We propose two metaheuristics based on greedy randomized adaptive search procedures (GRASP), variable neighborhood descent (VND) and evolutionary local search (ELS) to solve this problem. To evaluate these metaheuristics we test them on a set of 32 randomly generated problems. The computational experiment shows that a multi-start evolutionary local search outperforms a GRASP/VND. Moreover, it obtains competitive results when applied to the multi-depot vehicle routing problem (MDVRP), that can be seen as a special case of the STTRPSD.     

Differences in day and night shift clinical performance in anesthesiology

OBJECTIVE: This study examined whether anesthesia residents (physicians in training) performed clinical duties in the operating room differently during the day versus at night. BACKGROUND: Fatigue from sleep deprivation and working through the night is common for physicians, particularly during residency training. METHODS: Using a repeated-measures design, we studied 13 pairs of day-night matched anesthesia cases. Dependent measures included task times, workload ratings, response to an alarm light latency task, and mood. RESULTS: Residents spent significantly less time on manual tasks and more time on monitoring tasks during the maintenance phase at night than during the day. Residents reported more negative mood at night than during the day, both pre- and postoperation. However, time of day had no effect on the mood change between pre- and postoperation. Workload ratings and the response time to an alarm light latency task were not significantly different between night and day cases. CONCLUSIONS: Because night shift residents had been awake and working for more than 16 hr, the observed differences in task performance and mood may be attributed to fatigue. The changes in task distribution during night shift work may represent compensatory strategies to maintain patient care quality while keeping perceived workload at a manageable level. APPLICATIONS: Fatigue effects during night shifts should be considered when designing work-rest schedules for clinicians. This matched-case control scheme can also be applied to study other phenomena associated with patient safety in the actual clinical environment.     

Nano-LC-MS/MS of glycopeptides produced by nonspecific proteolysis enables rapid and extensive site-specific glycosylation determination

Given the biological importance of glycosylation on proteins, the identification of protein glycosylation sites is integral to understanding broader biological structure and function. Unfortunately, the determination of the microheterogeneity at the site of glycosylation still remains a significant challenge. Nanoflow liquid chromatography with tandem mass spectrometry provides both separation of glycopeptides and the ability to determine glycan composition and site-specific glycosylation. However, because of the size of glycopeptides, they are not often amenable to tandem MS. In this work, proteins are digested with multiple proteases to produce glycopeptides that are of suitable size for tandem MS analysis. The conditions for collision-induced dissociation are optimized to obtain diagnostic ions that maximize glycan and peptide information. The method is applied to glycoproteins with contrasting glycans and multiple sites of glycosylation and identifies multiple glycan compositions at each individual glycosylation site. This method provides an important improvement in the routine determination of glycan microheterogeneity by mass spectrometry.     

A method of producing very fine ferrite grains by means of hot forming

It is well known that refining the grain size of metals should lead to an improvement in the mechanical properties both of strength and of toughness. Therefore, a method has to be improved for the formation of very fine ferrite grains during hot rolling. By means of hot compression tests using an IF‐type steel and a HSLA steel the effect of chemical composition, deformation temperature, strain and strain rate on the resulting ferrite grain size has been investigated. By optimising the different process parameters during hot deformation, a ferrite grain of ASTM 15 can be produced. By means of the Hall‐Petch relationship an estimation of the influence of ferrite grain refinement on the mechanical properties can be given.     

The influence of a martensitic phase transformation on stress development in thermal barrier coating systems

Thermal barrier coatings (TBCs) provide thermal insulation and oxidation protection of Ni-base superalloys in elevated temperature turbine applications. Thermal barrier coating failure is caused by spallation, which is related to the development of internal stresses during thermal cycling. Recent microstructural observations have highlighted the occurrence of a martensitic bond coat transformation, and this finite-element analysis was conducted to clarify the influence of the martensite on the development of stresses and strains in the multilayered system during thermal cycling. Simulations incorporating the volume change associated with the transformation and experimentally measured coating properties indicate that out-of-plane top coat stresses are greatly influenced by the presence of the martensitic transformation, the temperature at which it occurs relative to the strength of the bond coat and attendant bond coat plasticity. Intermediate values of bond coat strength and transformation temperatures are shown to result in the highest top coat stresses. This article is based on a presentation in the symposium “Terence E. Mitchell Symposium on the Magic of Materials: Structures and Properties” from the TMS Annual Meeting in San Diego, CA in March 2003.     

A systematic overview of the incidence of posterior capsule opacification

OBJECTIVE: Reported rates of posterior capsule opacification (PCO) vary widely and are based on various definitions of PCO, varying lengths and intervals of follow-up, and the use of different surgical techniques, intraocular lens (i.o.l.) designs, and methods of IOL implantation. This study was designed to obtain a more precise overall estimate of the incidence of PCO and to explore factors that might influence the rate of PCO development. DESIGN: A meta-analysis. METHODS: Published articles were selected for study based on a computerized MEDLINE search of the literature and a manual search of the bibliographies of relevant articles. Articles meeting selected inclusion criteria were reviewed systematically, and the reported data were abstracted and synthesized using the statistical techniques of meta-analysis. MAIN OUTCOME MEASURE: Pooled estimates of the proportion of eyes developing PCO at three postoperative timepoints--1 year, 3 years, and 5 years--were measured. RESULTS: There is significant heterogeneity among published rates of PCO. The overall pooled estimates (95% confidence limits) of the incidence of PCO were 11.8% (9.3%-14.3%) at 1 year, 20.7% (16.6%-24.9%) at 3 years, and 28.4% (18.4%-38.4%) at 5 years after surgery. There is no evidence of a significant decline in PCO incidence during the study period. CONCLUSIONS: Visually significant PCO develops in more than 25% of patients undergoing standard extracapsular cataract extraction or phacoemulsification with posterior chamber intraocular lens implantation over the first 5 years after surgery. Patient characteristics, surgical techniques, and differences in research design and reporting may account for some of the variability in reported rates. However, no specific factors were identified in the authors' analysis. More precise estimates of incidence and identification of risk factors for PCO will depend on the development of a standardized measurement of PCO and wider adoption of more rigorous study methodology.     

Faculty of color in academe: What 20 years of literature tells us.

To better prepare students for an increasingly diverse society, campuses across the country remain engaged in efforts to diversify the racial and ethnic makeup of their faculties. However, faculty of color remain seriously underrepresented, making up 17% of total full-time faculty. In the past 20 years, more than 300 authors have addressed the status and experience of faculty of color in academe. From 1988 to 2007, there was a continued rise in publications addressing the issue of the low representation of faculty of color. This article presents a literature review and synthesis of 252 publications, with the goal of informing scholars and practitioners of the current state of the field. Themes emerging from these publications and an interpretive model through which findings can be viewed are presented. The analysis, with a focus on the departmental, institutional, and national contexts, documents supports, challenges, and recommendations to address barriers and build on successes within these 3 contexts. The authors hope that this article informs researchers and practitioners as they continue their work to understand and promote the increased representation of faculty of color. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brief report: Exaggerated ethanol-induced cardiac reactivity as an indicator of increased risk for gambling.

Pathological gambling and alcohol dependence show a high rate of co-occurrence. Some individuals at risk for alcohol dependence display an exaggerated heart rate (HR) increase following alcohol consumption, a characteristic suggesting sensitivity to reward. This study examined whether exaggerated ethanol-induced cardiac reactivity was associated with increased gambling behaviors. One hundred five young men (M = 20.13 years, SD = 1.07) consumed 1 ml of ethanol (95% volume) per kilogram of body weight. HR was measured and participants completed the South Oaks Gambling Screen (SOGS; H. R. Lesieur & S. B. Blume, 1987). Those with higher intoxicated HRs reported significantly greater scores on the SOGS (p = .02). This suggests that ethanol-induced HR increase is a possible marker for addictive disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting career indecision: A self-determination theory perspective.

The purpose of this study was to propose and test a model of career indecision based on self-determination theory (E. L. Deci & R. M. Ryan, 1985). This model posits that peer and parental styles predicted career indecision through perceived self-efficacy and autonomy. Participants were 834 college students (236 men, 581 women, 17 without gender identification). Results from structural equation modeling provided support for the proposed model and showed that the model was invariant across gender. Discussion centers on the theoretical and practical implications of the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of selective excitotoxic lesions of the nucleus accumbens core, anterior cingulate cortex, and central nucleus of the amygdala on autoshaping performance in rats.

The nucleus accumbens core (AcbC), anterior cingulate cortex (ACC), and central nucleus of the amygdala (CeA) are required for normal acquisition of tasks based on stimulus-reward associations. However, it is not known whether they are involved purely in the learning process or are required for behavioral expression of a learned response. Rats were trained preoperatively on a Pavlovian autoshaping task in which pairing a visual conditioned stimulus (CS+) with food causes subjects to approach the CS+ while not approaching an impaired stimulus (CS-). Subjects then received lesions of the AcbC, ACC, or CeA before being retested. AcbC lesions severely impaired performance; lesioned subjects approached the CS + significantly less often than controls, failing to discriminate between the CS + and CS-. ACC lesions also impaired performance but did not abolish discrimination entirely. CeA lesions had no effect on performance. Thus, the CeA is required for learning, but not expression, of a conditioned approach response, implying that it makes a specific contribution to the learning of stimulus-reward associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)