Accelerated aging of solid lubricants for the W76-1 TSL : effects of polymer outgassing.

The behavior of MoS{sub 2} lubricants intended for the W76-1 TSL was evaluated after 17 and 82 thermal cycles, each lasting seven days and including a low temperature of -35 C and a high temperature of 93 C, in a sealed container containing organic materials. The MoS{sub 2} was applied by tumbling with MoS{sub 2} powder and steel pins (harperized), or by spraying with a resin binder (AS Mix). Surface composition measurements indicated an uptake of carbon and silicon on the lubricant surfaces after aging. Oxidation of the MoS{sub 2} on harperized coupons, where enough MoS{sub 2} was present at the surface to result in significant Mo and S concentrations, was found to be minimal for the thermal cycles in an atmosphere of primarily nitrogen. Bare steel surfaces showed a reduction in friction for exposed coupons compared to control coupons stored in nitrogen, at least for the initial cycles of sliding until the adsorbed contaminants were worn away. Lubricated surfaces showed no more than a ten percent increase in steady-state friction coefficient after exposure. Initial coefficient of friction was up to 250 percent higher than steady-state for AS Mix films on H950 coupons after 82 thermal cycles. However, the friction coefficient exhibited by lubricated coupons was never greater than 0.25, and more often less than 0.15, even after the accelerated aging exposures

Expert Consensus Recommendations for Robotic Surgery Credentialing

Objective: To define criteria for robotic credentialing using expert consensus. Background: A recent review of institutional robotic credentialing policies identified significant variability and determined current policies are largely inadequate to ensure surgeon proficiency and may threaten patient safety. Methods: 28 national robotic surgery experts were invited to participate in a consensus conference. After review of available institutional policies and discussion, the group developed a 91 proposed criteria. Using a modified Delphi process the experts were asked to indicate their agreement with the proposed criteria in three electronic survey rounds after the conference. Criteria that achieved 80% or more in agreement (consensus) in all rounds were included in the final list. Results: All experts agreed that there is a need for standardized robotic surgery credentialing criteria across institutions that promote surgeon proficiency. 49 items reached consensus in the first round, 19 in the second, and 8 in the third for a total of 76 final items. Experts agreed that privileges should be granted based on video review of surgical performance and attainment of clearly defined objective proficiency benchmarks. Parameters for ongoing outcome monitoring were determined and recommendations for technical skills training, proctoring, and performance assessment were defined. Conclusions: Using a systematic approach, detailed credentialing criteria for robotic surgery were defined. Implementation of these criteria uniformly across institutions will promote proficiency of robotic surgeons and has the potential to positively impact patient outcomes

Predicting physical activity by the personality styles of the five-factor model

Objective: Low neuroticism, high extraversion, and high conscientiousness are related to physical activity (PA). We tested whether the small size and heterogeneity of these relationships result because personality traits influence one another as well as because some narrow facets rather than the broad domains contain more specific variance relevant to PA. Method: Participants were men and women enrolled in the University of North Carolina Alumni Heart Study who completed the Revised NEO Personality Inventory (NEO-PI-R) and reported their past month’s average activity on an 8-point scale. In Study 1, we examined prospective correlations between the five NEO-PI-R domains and PA. In Studies 2 and 3, we used multinomial logistic regression to examine associations between PA and trait pair combinations (personality styles) controlling for age, sex, educational achievement, relationship status, and depression. Results: Study 1 revealed that lower neuroticism (N) and agreeableness (A) and higher conscientiousness (C) predicted more PA. Taken together, Studies 2 and 3 found that the combination of high Extraversion (E) and high openness (O) was related to higher PA and that combinations of low E and high A and low E and low C were related to lower PA. Study 3, which examined the activity facet of E (E4), found that E4 is an important driver of E—PA associations. Conclusions: Personality traits do not operate in isolation. They may influence how other traits are expressed and such nonadditive effects can impact PA. Assessment of personality styles could help to identify individuals at risk for PA avoidance and may be useful for developing personalized interventions

Self-Medication as Adaptive Plasticity: Increased Ingestion of Plant Toxins by Parasitized Caterpillars

Self-medication is a specific therapeutic behavioral change in response to disease or parasitism. The empirical literature on self-medication has so far focused entirely on identifying cases of self-medication in which particular behaviors are linked to therapeutic outcomes. In this study, we frame self-medication in the broader realm of adaptive plasticity, which provides several testable predictions for verifying self-medication and advancing its conceptual significance. First, self-medication behavior should improve the fitness of animals infected by parasites or pathogens. Second, self-medication behavior in the absence of infection should decrease fitness. Third, infection should induce self-medication behavior. The few rigorous studies of self-medication in non-human animals have not used this theoretical framework and thus have not tested fitness costs of self-medication in the absence of disease or parasitism. Here we use manipulative experiments to test these predictions with the foraging behavior of woolly bear caterpillars (Grammia incorrupta; Lepidoptera: Arctiidae) in response to their lethal endoparasites (tachinid flies). Our experiments show that the ingestion of plant toxins called pyrrolizidine alkaloids improves the survival of parasitized caterpillars by conferring resistance against tachinid flies. Consistent with theoretical prediction, excessive ingestion of these toxins reduces the survival of unparasitized caterpillars. Parasitized caterpillars are more likely than unparasitized caterpillars to specifically ingest large amounts of pyrrolizidine alkaloids. This case challenges the conventional view that self-medication behavior is restricted to animals with advanced cognitive abilities, such as primates, and empowers the science of self-medication by placing it in the domain of adaptive plasticity theory

How resilient is your team? Exploring healthcare providers’ well-being during the COVID-19 pandemic

Background: The global COVID-19 pandemic has placed tremendous physical and mental strain on the US healthcare system. Studies examining the effects of outbreaks have demonstrated both an increased prevalence and long-term development of Post-Traumatic Stress Disorder (PTSD) symptoms in healthcare providers. We sought to assess the impact of the COVID-19 pandemic on the psychological well-being of medical providers, medical trainees, and administrators at a large academic center to identify stressors and moderators to guide future mental health and hospital-system interventions. Methods: A 42-item survey examining specific stressors, grit, and resilience was widely distributed to physicians, residents, fellows, and administrators a large academic institution for departmental distribution. Survey results were analyzed using descriptive statistics, ANOVA, and multivariate linear regressions. A p-value <0.05 was considered statistically significant. Results: A total of 785 participants completed the survey. The majority of respondents rated their stress to be significantly increased during the pandemic. Respondents’ fear of transmitting the virus to their family members was a significant stressor. Higher resilience was associated with lower stress, anxiety, fatigue, and sleep disturbances. Overall, respondents felt supported by their departments and institution and felt contingency plans and personal protective equipment were adequate. Conclusions: Healthcare workers have increased resilience in the face of heightened stress during a pandemic. Higher resilience and grit were protective factors in managing personal and system-level stressors at the peak of the COVID-19 pandemic in our institution. Implementing an intervention designed to enhance healthcare workers’ resilience in response to the COVID-19 pandemic is warranted

A Competency-based Laparoscopic Cholecystectomy Curriculum Significantly Improves General Surgery Residents’ Operative Performance and Decreases Skill Variability: Cohort Study

Objective: To demonstrate the feasibility of implementing a CBE curriculum within a general surgery residency program and to evaluate its effectiveness in improving resident skill. Summary of Background Data: Operative skill variability affects residents and practicing surgeons and directly impacts patient outcomes. CBE can decrease this variability by ensuring uniform skill acquisition. We implemented a CBE LC curriculum to improve resident performance and decrease skill variability. Methods: PGY-2 residents completed the curriculum during monthly rotations starting in July 2017. Once simulator proficiency was reached, residents performed elective LCs with a select group of faculty at 3 hospitals. Performance at curriculum completion was assessed using LC simulation metrics and intraoperative operative performance rating system scores and compared to both baseline and historical controls, comprised of rising PGY-3s, using a 2-sample Wilcoxon rank-sum test. PGY-2 group’s performance variability was compared with PGY-3s using Levene robust test of equality of variances; P < 0.05 was considered significant. Results: Twenty-one residents each performed 17.52 ± 4.15 consecutive LCs during the monthly rotation. Resident simulated and operative performance increased significantly with dedicated training and reached that of more experienced rising PGY-3s (n = 7) but with significantly decreased variability in performance (P = 0.04). Conclusions: Completion of a CBE rotation led to significant improvements in PGY-2 residents’ LC performance that reached that of PGY-3s and decreased performance variability. These results support wider implementation of CBE in resident training

A Generalizable Multimodal Scrub Training Curriculum in Surgical Sterile Technique

Introduction: Recent endeavors from governing bodies such as the AAMC have formally recognized the importance of aseptic technique. AAMC guidelines include activities that all graduating physicians should be able to perform with minimum indirect supervision and were developed to recognize these needs. For example, the skills necessary for aseptic technique include daily safety habits and general physician procedures. Methods: We developed a scrub training curriculum and evaluated the program through a quasi-experimental study with a pre- and posttest design. Questions were developed to examine students' perceived knowledge and skills as related to the objectives of the course and to their anxieties, concerns, and future training needs. Results: Between February 2020 and March 2020, 44 students completed the curriculum. Students indicated that self-efficacy significantly increased in all aspects of the curricular goals following curriculum completion. Students identified understanding OR etiquette as the most anxiety-provoking element associated with scrub training. They felt that more time could be spent elucidating this etiquette. On the other hand, tasks such as surgical hand hygiene were the least anxiety-inducing. Discussion: We share this multimodal scrub training curriculum, mapped to the AAMC's guidelines, to reduce variability in teaching strategies and skills acquisition through a standardized curriculum. Also, we effectively imparted these skills and instilled a sense of confidence in learners as they worked to provide their best in patient care and safety

Challenges in quantifying changes in the global water cycle

Human influences have likely already impacted the large-scale water cycle but natural variability and observational uncertainty are substantial. It is essential to maintain and improve observational capabilities to better characterize changes. Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time-series over land but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols, and due to large climate variability presently limits confidence in attribution of observed changes

Measurement of the Lifetime Difference Between B_s Mass Eigenstates

We present measurements of the lifetimes and polarization amplitudes for B_s --> J/psi phi and B_d --> J/psi K*0 decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B_s system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203 +/- 15 B_s decays, we obtain tau_L = (1.05 +{0.16}/-{0.13} +/- 0.02) ps and tau_H = (2.07 +{0.58}/-{0.46} +/- 0.03) ps. Expressed in terms of the difference DeltaGamma_s and average Gamma_s, of the decay rates of the two eigenstates, the results are DeltaGamma_s/Gamma_s = (65 +{25}/-{33} +/- 1)%, and DeltaGamma_s = (0.47 +{0.19}/-{0.24} +/- 0.01) inverse ps.Comment: 8 pages, 3 figures, 2 tables; as published in Physical Review Letters on 16 March 2005; revisions are for length and typesetting only, no changes in results or conclusion

The ecology and epidemiology of malaria parasitism in wild chimpanzee reservoirs

This work was supported by grants from the National Institutes of Health R01AI091595, R01AI120810, R01AI050529, and P30AI045008 (B.H.H.); R01HL139337 (M.T.D.), the National Geographic Society (E.J.S.), the International Primatological Society (E.J.S.), and the American Society of Primatologists (E.J.S.), as well as fellowships from Harvard University (E.J.S.) and the National Science Foundation (E.J.S.).Chimpanzees (Pan troglodytes) harbor rich assemblages of malaria parasites, including three species closely related to P. falciparum (sub-genus Laverania), the most malignant human malaria parasite. Here, we characterize the ecology and epidemiology of malaria infection in wild chimpanzee reservoirs. We used molecular assays to screen chimpanzee fecal samples, collected longitudinally and cross-sectionally from wild populations, for malaria parasite mitochondrial DNA. We found that chimpanzee malaria parasitism has an early age of onset and varies seasonally in prevalence. A subset of samples revealed Hepatocystis mitochondrial DNA, with phylogenetic analyses suggesting that Hepatocystis appears to cross species barriers more easily than Laverania. Longitudinal and cross-sectional sampling independently support the hypothesis that mean ambient temperature drives spatiotemporal variation in chimpanzee Laverania infection. Infection probability peaked at ~24.5 °C, consistent with the empirical transmission optimum of P. falciparum in humans. Forest cover was also positively correlated with spatial variation in Laverania prevalence, consistent with the observation that forest-dwelling Anophelines are the primary vectors. Extrapolating these relationships across equatorial Africa, we map spatiotemporal variation in the suitability of chimpanzee habitat for Laverania transmission, offering a hypothetical baseline indicator of human exposure risk.Publisher PDFPeer reviewe