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Recent studies illustrate how machine learning (ML) can be used to bypass a core challenge of molecular modeling: the trade-off between accuracy and computational cost. Here, we assess multiple ML approaches for predicting the atomization energy of organic molecules. Our resulting models learn the difference between low-fidelity, B3LYP, and high-accuracy, G4MP2, atomization energies and predict the G4MP2 atomization energy to 0.005 eV (mean absolute error) for molecules with less than nine heavy atoms (training set of 117,232 entries, test set 13,026) and 0.012 eV for a small set of 66 molecules with between 10 and 14 heavy atoms. Our two best models, which have different accuracy/speed trade-offs, enable the efficient prediction of G4MP2-level energies for large molecules and are available through a simple web interface.
With growing demand for better fuel economy for automobiles, multimaterial solutions are increasingly being utilized in the automotive industry for reducing weight in the vehicle body structure. This poses challenges in terms of joining dissimilar metals, especially those with vastly different properties such as aluminum to steel joining. General Motors has developed a new resistance spot-welding technique for dissimilar materials using a multi-ring domed (MRD) electrode and multiple solidification weld schedules to address this challenge. Originally developed for aluminum to aluminum resistance spot welding, this technology is being deployed as the mainstream aluminum joining solution to leverage existing infrastructure and workforce competency in resistance spot welding. With the recent expansion of MRD technology to aluminum to steel resistance spot welding, there is an ever-greater need to experimentally verify the quality of each aluminum to steel resistance spot-weld application with limited time and resources. Nondestructive evaluation (NDE) would enable the transfer of resistance spot-welding technology to dissimilar aluminum to steel joints. This article describes the current state of the art of aluminum to steel resistance spot welding and the challenges in developing a robust NDE process for this technology.
Vaporizing foil actuator welding is a form of impact welding, which can be carried out without the use of chemical explosives. Operating at smaller length scales, but with similar driving pressures as explosive welding, vaporizing foil actuator welding is capable of welding a wide variety of advanced and dissimilar metal combinations. With negligible heating developing during the process, thermal distortion does not occur, and the base-metal properties are retained in the weld. In this article, vaporizing foil actuator welding of an automotive grade aluminum and steel pair is discussed. A currently functional and complete welding system that can be used for research as well as low volume production is also discussed.
To assess variability in antimicrobial use and associations with infection testing in pediatric ventilator-associated events (VAEs).
Descriptive retrospective cohort with nested case-control study.
Pediatric intensive care units (PICUs), cardiac intensive care units (CICUs), and neonatal intensive care units (NICUs) in 6 US hospitals.
Children≤18 years ventilated for≥1 calendar day.
We identified patients with pediatric ventilator-associated conditions (VACs), pediatric VACs with antimicrobial use for≥4 days (AVACs), and possible ventilator-associated pneumonia (PVAP, defined as pediatric AVAC with a positive respiratory diagnostic test) according to previously proposed criteria.
Among 9,025 ventilated children, we identified 192 VAC cases, 43 in CICUs, 70 in PICUs, and 79 in NICUs. AVAC criteria were met in 79 VAC cases (41%) (58% CICU; 51% PICU; and 23% NICU), and varied by hospital (CICU, 20–67%; PICU, 0–70%; and NICU, 0–43%). Type and duration of AVAC antimicrobials varied by ICU type. AVAC cases in CICUs and PICUs received broad-spectrum antimicrobials more often than those in NICUs. Among AVAC cases, 39% had respiratory infection diagnostic testing performed; PVAP was identified in 15 VAC cases. Also, among AVAC cases, 73% had no associated positive respiratory or nonrespiratory diagnostic test.
Antimicrobial use is common in pediatric VAC, with variability in spectrum and duration of antimicrobials within hospitals and across ICU types, while PVAP is uncommon. Prolonged antimicrobial use despite low rates of PVAP or positive laboratory testing for infection suggests that AVAC may provide a lever for antimicrobial stewardship programs to improve utilization.
Children with poor mental health often struggle at school. The relationship between childhood psychiatric disorder and exclusion from school has not been frequently studied, but both are associated with poor adult outcomes. We undertook a secondary analysis of the British Child and Adolescent Mental Health Surveys from 2004 and its follow-up in 2007 to explore the relationship between exclusion from school and psychopathology. We predicted poorer mental health among those excluded.
Psychopathology was measured using the Strengths and Difficulties Questionnaire, while psychiatric disorder was assessed using the Development and Well-Being Assessment and applying Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM IV) criteria. Exclusion from school and socio-demographic characteristics were reported by parents. Multi-variable regression models were used to examine the impact of individual factors on exclusion from school or psychological distress.
Exclusion from school was commoner among boys, secondary school pupils and those living in socio-economically deprived circumstances. Poor general health and learning disability among children and poor parental mental health were also associated with exclusion. There were consistently high levels of psychological distress among those who had experienced exclusion at baseline and follow-up.
We detected a bi-directional association between psychological distress and exclusion. Efforts to identify and support children who struggle with school may therefore prevent both future exclusion and future psychiatric disorder.
According to cognitive averaging theory, preferences for attractive faces result from their similarity to facial prototypes, the categorical central tendencies of a population of faces. Prototypical faces are processed more fluently, resulting in increased positive affect in the viewer.
Adult ventilator-associated event (VAE) definitions include ventilator-associated conditions (VAC) and subcategories for infection-related ventilator-associated complications (IVAC) and possible ventilator-associated pneumonia (PVAP). We explored these definitions for children.
Pediatric, cardiac, or neonatal intensive care units (ICUs) in 6 US hospitals
Patients ≤18 years old ventilated for ≥1 day
We identified patients with pediatric VAC based on previously proposed criteria. We applied adult temperature, white blood cell count, antibiotic, and culture criteria for IVAC and PVAP to these patients. We matched pediatric VAC patients with controls and evaluated associations with adverse outcomes using Cox proportional hazards models.
In total, 233 pediatric VACs (12,167 ventilation episodes) were identified. In the cardiac ICU (CICU), 62.5% of VACs met adult IVAC criteria; in the pediatric ICU (PICU), 54.2% of VACs met adult IVAC criteria; and in the neonatal ICU (NICU), 20.2% of VACs met adult IVAC criteria. Most patients had abnormal white blood cell counts and temperatures; we therefore recommend simplifying surveillance by focusing on “pediatric VAC with antimicrobial use” (pediatric AVAC). Pediatric AVAC with a positive respiratory diagnostic test (“pediatric PVAP”) occurred in 8.9% of VACs in the CICU, 13.3% of VACs in the PICU, and 4.3% of VACs in the NICU. Hospital mortality was increased, and hospital and ICU length of stay and duration of ventilation were prolonged among all pediatric VAE subsets compared with controls.
We propose pediatric AVAC for surveillance related to antimicrobial use, with pediatric PVAP as a subset of AVAC. Studies on generalizability and responsiveness of these metrics to quality improvement initiatives are needed, as are studies to determine whether lower pediatric VAE rates are associated with improvements in other outcomes.
Mineral soils in the McMurdo Dry Valleys (MDV), Antarctica, are commonly considered to be dry, and therefore to be good insulators with low thermal diffusivity values (~0.2 mm2 s-1). However, field measurements of soil moisture profiles with depth, coupled with observations of rapid ground ice melt, suggest that the thermal characteristics of MDV soils, and thus their resistance to thaw, may be spatially variable and strongly controlled by soil moisture content. The thermal conductivity, heat capacity and thermal diffusivity of 17 MDV soils were measured over a range of soil moisture conditions from dry to saturated. We found that thermal diffusivity varied by a factor of eight for these soils, despite the fact that they consist of members of only two soil groups. The thermal diffusivity of the soils increased in all cases with increasing soil moisture content, suggesting that permafrost and ground ice thaw in mineral soils may generate a positive thawing feedback in which wet soils conduct additional heat to depth, enhancing rates of permafrost thaw and thermokarst formation.
Anti-black prejudice affects how some citizens evaluate black candidates. What does it take to reduce the role of prejudice in these evaluations? Using logical implications of relevant psychological phenomena, this article shows that repeated exposure to counter-stereotypical information is insufficient to reduce evaluative prejudice. Instead, citizens must associate this prejudice with adverse effects for themselves in contexts that induce them to rethink their existing racial beliefs. These findings explain important disagreements in empirical prejudice research, as only some empirical research designs supply the conditions for prejudice reduction predicted here. This study also clarifies why similarly situated citizens react so differently to counter-stereotypical information. In sum, we find that prejudice change is possible, but in a far narrower set of circumstances than many scholars claim.
In the presented study, a new application for distyrylbenzene oligoelectrolyte, named DSBN+, as a marker for bioimaging is presented. DSBN+ is a water-soluble, conjugated oligoelectrolyte (COE) with novel photophysical and solvatochromatic properties. Previous studies have shown that this compound spontaneously inserts into bilayer membranes in both synthetic and microbial living systems and can facilitate visualization of cell membranes through fluorescence imaging. In the presented research, we seek to further study and exploit the multifunctional nature of DSBN+ in terms of membrane interactions and photophysical properties for visualization of membranous structures of more complex mammalian cells, namely a human cervical carcinoma (HeLa) cell line. Obtained results confirm the possibility of applying DSBN+ as a fluorescent dye for bioimaging of membranes in human cell cultures systems, both in live-cell imaging and in the studies required formaldehyde fixation. Due to the defined structure of this conjugated oligoelectrolyte we suspect that it will display organelle membrane selectivity, but this has to be further investigated.
We present an agent-based model of the key activities of a troop of chacma baboons (Papio hamadryas ursinus) based on data collected at De Hoop Nature Reserve in South Africa. The construction of the model identified some key elements that were missing from the field data that would need to be collected in subsequent fieldwork. We analyse the predictions of the model in terms of how well it is able to duplicate the observed activity patterns of the animals and the relationship between the parameters that control the agent's decision procedure and the model's predictions. At the current stage of model development, we are able to show that, across a wide range of decision parameter values, the baboons are able to achieve their energetic and social time requirements. The simulation results show that decisions concerning movement (group action selection) have the greatest influence on the outcomes. Group decision making is a fertile field for future research, and agent-based modelling offers considerable scope for understanding group action selection.
Group living is a common strategy among mammals and is key to understanding the success of the primate order in general and early humans in particular. For animals that forage or move in social groups, decisions about when and where to move often depend upon social interactions between group members (Krause and Ruxton, 2002; Couzin et al., 2005). Little is actually known, however, about how groups of animals arrive at such collective decisions (Conradt and Roper, 2003). We focus on the problem of action selection in groups, i.e., where an individual's action choice is constrained by the choices of other members of the group.
1-Octen-3-ol is a kairomone for many haematophagous insects including mosquitoes. Numerous studies have examined the effects of racemic 1-octen-3-ol; however, few studies have investigated the role of individual enantiomers in relation to mosquito attraction. In the present study, we investigated the behavioural and electrophysiological responses of two mosquito species, Aedes aegypti and Culex quinquefasciatus, to individual enantiomers and mixtures of 1-octen-3-ol, employing a laboratory Y-tube olfactometer and single sensillum recordings. The olfactory receptor neurons of both Ae. aegypti and Cx. quinquefasciatus had a significantly higher response to the (R)-1-octen-3-ol enantiomer compared to the (S)-1-octen-3-ol enantiomer at 10−9 g μl−1 to 10−6 g μl−1. Behaviourally, Ae. aegypti was more responsive to the (R)-1-octen-3-ol enantiomer, showing an increase in flight activity and relative attraction compared to Cx. quinquefasciatus. The (R)-1-octen-3-ol enantiomer caused an increase in activation for Cx. quinquefasciatus. However, the most notable effect was from an (R:S)-1-octen-3-ol mixture (84:16) that caused significantly more mosquitoes to sustain their flight and reach the capture chambers (demonstrated by a reduced non-sustained flight activity), suggesting that it may have a behaviourally excitatory effect. For Cx. quinquefasciatus, a reduced relative attraction response was also observed for all treatments containing the (R)-1-octen-3-ol enantiomer, either on its own or as part of a mixture, but not with the (S)-1-octen-3-ol enantiomer. This is the first time enantiomeric selectivity has been shown for Ae. aegypti using electrophysiology in vivo. The implications of these results for exploitation in mosquito traps are discussed.
Diet is associated with the development of CHD. The incidence of CHD is lower in southern European countries than in northern European countries and it has been proposed that this difference may be a result of diet. The traditional Mediterranean diet emphasises a high intake of fruits, vegetables, bread, other forms of cereals, potatoes, beans, nuts and seeds. It includes olive oil as a major fat source and dairy products, fish and poultry are consumed in low to moderate amounts. Many observational studies have shown that the Mediterranean diet is associated with reduced risk of CHD, and this result has been confirmed by meta-analysis, while a single randomised controlled trial, the Lyon Diet Heart study, has shown a reduction in CHD risk in subjects following the Mediterranean diet in the secondary prevention setting. However, it is uncertain whether the benefits of the Mediterranean diet are transferable to other non-Mediterranean populations and whether the effects of the Mediterranean diet will still be feasible in light of the changes in pharmacological therapy seen in patients with CHD since the Lyon Diet Heart study was conducted. Further randomised controlled trials are required and if the risk-reducing effect is confirmed then the best methods to effectively deliver this public health message worldwide need to be considered.
We describe the first cluster of cases of necrotizing fasciitis (NF) in this century in the United Kingdom (UK). Between 1 January and 30 June 1994 there were six cases (five confirmed, one probable) of Streptococcus pyogenes NF in west Gloucestershire, population 320000. Two cases died. The first two patients probably acquired their infections during the course of elective surgery performed in the same operating theatre, possibly from a nasopharyngeal carrier amongst the theatre staff. The remaining infections were community-acquired. Of 5 S. pyogenes isolates there were 2 M1 strains, 1 M3, 1 M5 and 1 M non-typeable strain. S. pyogenes NF had not been recorded in west Gloucestershire in the preceding 10 years and the incidence of S. pyogenes bacteraemia in England and Wales had not risen in the past 5 years.
The two presumably theatre-acquired infections raised several issues. The need for detailed bacteriological investigation of all cases of post-surgical NF was confirmed. Clusters of S. pyogenes infection following surgery should be managed by closure of the operating theatre until all staff have been screened for carriage. Closure of an operating theatre and screening of staff following a sporadic case is probably not justified because of the infrequency of surgical cross-infection with S. pyogenes. Regular, routine screening of theatre staff is neither practical nor necessary.
Recent studies have suggested that untreated coeliac disease is associated with lower total cholesterol than in the general population while the effect of treatment with a gluten-free diet on the cholesterol profile of clinically apparent coeliac disease is not known. We measured the cholesterol profile at diagnosis, and compared this with Health Survey for England figures, and again following 12 months treatment with a gluten-free diet in 100 consecutive adults with coeliac disease attending the Royal Hallamshire Hospital, Sheffield, UK. The mean total cholesterol was 4·84 (sd 1·2) mmol/l in adults (mean age 51 (sd 16) years) newly diagnosed with coeliac disease. At diagnosis of coeliac disease, men had 21 % lower and women had 9 % lower mean total cholesterol in comparison to the general population (difference in age-adjusted mean total cholesterol − 1·09 mmol/l (95 % CI − 0·97, − 1·21); − 0·46 mmol/l (95 % CI − 0·24, − 0·68), respectively). There was no change in mean total cholesterol following treatment. However, there was a small but statistically significant increase of 0·12 mmol/l (95 % CI 0·05, 0·18) in the mean HDL-cholesterol. Total cholesterol was lower at diagnosis in coeliac patients than in the general population and did not increase with 1 year of a gluten-free diet while HDL-cholesterol increased following treatment. Any increase in risk of IHD or stroke in people with coeliac disease is unlikely due to an adverse cholesterol profile either before diagnosis or after treatment with a gluten-free diet.
From examining the remains of charred cowpeas from rock shelters in Central Ghana, the authors throw light on the subsistence strategies of the Kintampo people of the second millennium BCE. Perhaps driven southwards from the Sahel by aridification, the Kintampo operated as both foragers and farmers, cultivating selected plants of the West African tropics, notably cowpea, pearl millet and oil palm.
We investigated language representation in nine children (six male,
three female; 5.6–17.7 years of age) who underwent surgical
treatment of medically intractable epilepsy of the left hemisphere.
Although interhemispheric reorganization has been previously
documented in similar groups, this is the first study to systematically
evaluate possible intrahemispheric effects of early insult. All
cases had left hemisphere seizure foci and underwent extraoperative
stimulation mapping (ESM) for language localization prior to receiving
cortical resections. To compare ESM findings across subjects and to assess
intrahemispheric reorganization, we developed a novel
coregistration technique whereby independent raters plotted
two-dimensional (2D) ESM findings in 3D standard space. Expressive
language sites identified with ESM were compared with a structural
probability map of pars opercularis, or Broca's area. The
average difference between independent raters' estimates of 28
language sites was 3.9 mm (SD = 2.0), indicating excellent agreement; the
coregistration procedure permitted assessment of 2D ESM findings in 3D
standard space. We observed language sites in regions substantially
anterior and superior to canonical Broca's area, possibly reflecting
intrahemispheric reorganization. Findings suggest that left hemisphere
insult in young children may result in anterior displacement of language
within the frontal cortex. (JINS, 2007, 13,
505–516.)This study was drawn from a
thesis submitted by D.S.K. in partial fulfillment of requirements of the
MA degree through the Graduate Program in Psychology and the Collaborative
Program in Neuroscience at the University of Toronto (Ontario,
Vero cytotoxin-producing Escherichia coli O157 (VTEC O157) infections are a threat to public health. VTEC O157 has been isolated from gulls but evidence of transmission to humans from birds has not been reported. We recount an incident of VTEC O157 infection affecting two sibling children who had no direct contact with farm animals. An outbreak control team was convened to investigate the source of infection, its likely mode of transmission, and to advise on control measures. Human and veterinary samples were examined and the human isolates were found to be identical to an isolate from a sample of bird (rook) faeces. Cattle, rabbit and environmental samples were negative. This report provides evidence that birds may act as intermediaries for human infection with VTEC O157.