Reducing the Computational Cost of Ab Initio Methods

In recent years, advances in computer technology combined with new ab initio computational methods have allowed for dramatic improvement in the prediction of energetic properties. Unfortunately, even with these advances, the extensive computational cost, in terms of computer time, memory, and disk space of the sophisticated methods required to achieve chemical accuracy - defined as 1 kcal/mol from reliable experimental data effectively - limits the size of molecules [i.e. less than 10-15 non-hydrogen atoms] that can be studied. Several schemes were explored to help reduce the computational cost while still maintaining chemical accuracy. Specifically, a study was performed to assess the accuracy of ccCA to compute atomization energies, ionization potentials, electron affinities, proton affinities, and enthalpies of formation for third-row (Ga-Kr) containing molecules. Next, truncation of the correlation consistent basis sets for the hydrogen atom was examined as a possible means to reduce the computational cost of ab initio methods. It was determined that energetic properties could be extrapolated to the complete basis set (CBS) limit utilizing a series of truncated hydrogen basis sets that was within 1 kcal/mol of the extrapolation of the full correlation consistent basis sets. Basis set truncation for the hydrogen atom was then applied to ccCA in the development of two reduced basis set composite methods, ccCA(aug) and ccCA(TB). The effects that the ccCA(aug) and ccCA(TB) methods had upon enthalpies of formation and the overall percent disk space saved as compared to ccCA was examined for the hydrogen containing molecules of the G2/97 test suite. Additionally, the Weizmann-n (Wn) methods were utilized to compute the several properties for the alkali metal hydroxides as well as the ground and excited states of the alkali monoxides anion and radicals. Finally, a multi-reference variation to the correlation consistent Composite Approach [MR-ccCA] was presented and utilized in the computation of the potential energy surfaces for the N2 and C2 molecules

High early mortality following percutaneous nephrostomy in metastatic cancer:a national analysis of outcomes

Objectives: To assess the outcomes of percutaneous nephrostomy in England for renal decompression, in the context of metastatic cancer.Methods: Retrospective observational study of all patients undergoing nephrostomy with a diagnosis of metastatic cancer from 2010 to 2019 in England, identified and followed up within Hospital Episode Statistics.The primary outcome measure was mortality (14-day and 30-day postprocedure). Secondary outcomes included subsequent chemotherapy or surgery and direct complications of nephrostomy.Results: 10 932 patients were identified: 58.0% were male, 51.0% were &gt;70 years old and 57.7% had no relevant comorbidities (according to Charlson’s criteria, other than cancer).1 in 15 patients died within 14 days of nephrostomy and 1 in 6 died within 30 days. Factors associated with higher 30-day mortality were the presence of comorbidities (Charlson score 1–4 (OR 1.27, 95% CI 1.08 to 1.50, p=0.003), score 5+ (OR 1.29, 95% CI 1.14 to 1.45), p &lt; 0.001)); inpatient nephrostomy (OR 3.76, 95% CI 2.75 to 5.14, p &lt; 0.001) and admitted under the care of specialities of internal medicine (OR 2.10, 95% CI 1.84 to 2.40, p &lt; 0.001), oncology (OR 1.80, 95% CI 1.51 to 2.15, p &lt; 0.001), gynaecology/gynaeoncology (OR 1.66, 95% CI 1.21 to 2.28, p=0.002) or general surgery (OR 1.62, 95% CI 1.32 to 1.98, p &lt; 0.001)), compared with urology.25.4% received subsequent chemotherapy. Receiving chemotherapy was associated with younger patients (eg, age 18–29 (OR 4.04, 95% CI 2.66 to 6.12, p &lt; 0.001) and age 30–39 (OR 3.07, 95% CI 2.37 to 3.97, p &lt; 0.001)) and under the care of oncology (OR 1.60, 95% CI 1.40 to 1.83, p &lt; 0.001) or gynaecology/gynaeoncology (OR 1.64, 95%CI 1.28 to 2.10, p &lt; 0.001) compared with urology.43.8% had subsequent abdominopelvic surgery. Not receiving surgery was associated with inpatient nephrostomy (OR 0.82, 95%CI 0.72 to 0.95,p=0.007): non-genitourinary cancers (eg, gynaecology/gynaeoncology cancer (OR 0.86, 95% CI 0.74 to 0.99, p=0.037)); and under the care of a non-surgical specialty (medicine (OR 0.69, 95% CI 0.63 to 0.77, p &lt; 0.001), oncology (OR 0.58, 95% CI 0.51 to 0.66, p &lt; 0.001)).24.5% of patients had at least one direct complication of nephrostomy: 12.5% required early exchange of nephrostomy, 8.1% had bleeding and 6.7% had pyelonephritis.Conclusions: The decision to undertake nephrostomy in patients with poor prognosis cancer is complex and should be undertaken in a multidisciplinary team setting. Complication rates are high and minimal survival benefit is derived in many patients, especially in the context of emergency inpatient care.</div

Smoke gets in your eyes:what is sociological about cigarettes?

Contemporary public health approaches increasingly draw attention to the unequal social distribution of cigarette smoking. In contrast, critical accounts emphasize the importance of smokers’ situated agency, the relevance of embodiment and how public health measures against smoking potentially play upon and exacerbate social divisions and inequality. Nevertheless, if the social context of cigarettes is worthy of such attention, and sociology lays a distinct claim to understanding the social, we need to articulate a distinct, positive and systematic claim for smoking as an object of sociological enquiry. This article attempts to address this by situating smoking across three main dimensions of sociological thinking: history and social change; individual agency and experience; and social structures and power. It locates the emergence and development of cigarettes in everyday life within the project of modernity of the nineteenth and twentieth centuries. It goes on to assess the habituated, temporal and experiential aspects of individual smoking practices in everyday lifeworlds. Finally, it argues that smoking, while distributed in important ways by social class, also works relationally to render and inscribe it

Non-adjacent dependency learning in humans and other animals

International audienc

Simulation of potential impacts of man-made land use changes on U.S. summer climate under various synoptic regimes

This study evaluates impacts of land use changes due to human settlement on regional summer climate over the central and western United States by performing 30-day simulations during normal, drought, and flood years. Under current land use the simulated evapotranspiration increased noticeably over the central United States where grassland has been replaced by crops. Simulated evapotranspiration decreased slightly in the western United States. These changes produced wetter and cooler surface air over the central United States and slightly drier and warmer air over the western United States. Responses of surface fluxes and thus screen height variables to land use changes were consistent from year to year, whereas rainfall showed strong interannual variations because of the combination of various dynamic processes involved in precipitation. For normal year conditions, average evapotranspiration and rainfall under current land use increased by 18% and 8%, respectively, over the central United States, whereas they slightly decreased in the western United States. In both flood and drought years, current land use exhibited a rainfall increase in the western United States and a decrease over the central United States. The decrease of rainfall with increased evapotranspiration in the central United States was likely associated with weakening of the dynamic forcing needed to produce precipitation

Acting on Reflection: the Effect of Reflection on Students’ Clinical Performance on a Standardized Patient Examination

BACKGROUND: Little evidence exists to support the value of reflection in the clinical setting. OBJECTIVE: To determine whether reflecting and revisiting the “patient” during a standardized patient (SP) examination improves junior medical students’ performance and to analyze students’ perceptions of its value. DESIGN: Students completed a six-encounter clinical skills examination, writing a guided assessment after each encounter to trigger reflection. SPs evaluated the students with Medical Skills and Patient Satisfaction checklists. During the last three encounters, students could opt to revisit the SP and be reevaluated with identical checklists. PARTICIPANTS: One hundred and forty-nine third year medical students. MEASUREMENTS: Changes in scores in the Medical Skills and Patient Satisfaction checklists between first visit and revisit were tested separately per case as well as across cases. RESULTS: On the medical skills and patient satisfaction checklists, mean revisit scores across cases were significantly higher than mean first visit scores [12.6 vs 12.2 (pooled SD = 2.4), P = .0001; 31.2 vs 31.0 (pooled SD = 3.5), P = .0001)]. Sixty-five percent of the time, students rated “reflect–revisit” positively, 34% neutrally, and 0.4% negatively. Five themes were identified in the positive comments: enhancement of (1) medical decision making, (2) patient education/counseling, (3) student satisfaction/confidence, (4) patient satisfaction/confidence, and (5) clinical realism. CONCLUSIONS: Offering third year medical students the option to reflect and revisit an SP during a clinical skills examination produced a small but nontrivial increase in clinical performance. Students perceived the reflect–revisit experience as enhancing patient-centered practices (counseling, education) as well as their own medical decision making and clinical confidence

Animal-related factors associated with moderate-to-severe diarrhea in children younger than five years in western Kenya: A matched case-control study

Background Diarrheal disease remains among the leading causes of global mortality in children younger than 5 years. Exposure to domestic animals may be a risk factor for diarrheal disease. The objectives of this study were to identify animal-related exposures associated with cases of moderate-to-severe diarrhea (MSD) in children in rural western Kenya, and to identify the major zoonotic enteric pathogens present in domestic animals residing in the homesteads of case and control children. Methodology/Principal findings We characterized animal-related exposures in a subset of case and control children (n = 73 pairs matched on age, sex and location) with reported animal presence at home enrolled in the Global Enteric Multicenter Study in western Kenya, and analysed these for an association with MSD. We identified potentially zoonotic enteric pathogens in pooled fecal specimens collected from domestic animals resident at children’s homesteads. Variables that were associated with decreased risk of MSD were washing hands after animal contact (matched odds ratio [MOR] = 0.2; 95% CI 0.08–0.7), and presence of adult sheep that were not confined in a pen overnight (MOR = 0.1; 0.02–0.5). Variables that were associated with increased risk of MSD were increasing number of sheep owned (MOR = 1.2; 1.0–1.5), frequent observation of fresh rodent excreta (feces/urine) outside the house (MOR = 7.5; 1.5–37.2), and participation of the child in providing water to chickens (MOR = 3.8; 1.2–12.2). Of 691 pooled specimens collected from 2,174 domestic animals, 159 pools (23%) tested positive for one or more potentially zoonotic enteric pathogens (Campylobacter jejuni, C. coli, non-typhoidal Salmonella, diarrheagenic E. coli, Giardia, Cryptosporidium, or rotavirus). We did not find any association between the presence of particular pathogens in household animals, and MSD in children. Conclusions and significance Public health agencies should continue to promote frequent hand washing, including after animal contact, to reduce the risk of MSD. Future studies should address specific causal relations of MSD with sheep and chicken husbandry practices, and with the presence of rodents