Stabilization of mid-sized silicon nanoparticles by functionalization with acrylic acid

We present an enhanced method to form stable dispersions of medium-sized silicon nanoparticles for solar cell applications by thermally induced grafting of acrylic acid to the nanoparticle surface. In order to confirm their covalent attachment on the silicon nanoparticles and to assess the quality of the functionalization, X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier spectroscopy measurements were carried out. The stability of the dispersion was elucidated by dynamic light scattering and Zeta-potential measurements, showing no sign of degradation for months

Combined student ratings and self-assessment provide useful feedback for clinical teachers

Many evaluation instruments have been developed to provide feedback to physicians on their clinical teaching but written feedback alone is not always effective. We explored whether feedback effectiveness improved when teachers’ self-assessment was added to written feedback based on student ratings. 37 physicians (10 residents, 27 attending physicians) from different specialties (Internal Medicine, Surgery, Obstetrics/Gynecology, Pediatrics, Neurology, Dermatology, Ophthalmology, ENT, and Psychiatry) were invited to fill out a self-assessment questionnaire on their teaching skills. Students completed an almost identical questionnaire to evaluate the same teachers based on their experiences during clerkships. After receiving written feedback incorporating their self-assessment and the student ratings, the teachers indicated their perceptions of the self-assessment exercise and the written feedback in a questionnaire (five-point Likert scale items) and next, in more detail, in semi-structured interviews with a purposive sample of 12 of the participating teachers. 25 physicians participated (67%). The results showed that self-assessment and student feedback were both perceived as useful (3.7, SD 1.0) but the latter was considered more effective. The physicians we interviewed considered the combination of self-assessment with student ratings more effective than either self-assessment or written feedback alone. Notably, discrepancies between student ratings and self-assessment were deemed a strong incentive for change. We conclude that self-assessment can be a useful tool to stimulate improvement of clinical teaching when it is combined with written feedback based on student ratings. Future research among larger groups is needed to confirm our findings and examine whether these combined tools actually lead to improved teaching

Emergent global patterns of ecosystem structure and function from a mechanistic general ecosystem model

Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g., growth rate), community (e.g., biomass turnover rates), ecosystem (e.g., trophic pyramids), and macroecological scales (e.g., global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global, and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures

Family history in stone disease: how important is it for the onset of the disease and the incidence of recurrence?

The aim of this study was to evaluate the possible effect of a positive family history on the age at the onset of urinary stone disease and the frequency of subsequent symptomatic episodes relating to the disease. Between March 2006 and April 2009, patients with either a newly diagnosed or a previously documented stone disease were included in the study program. They were required to fill in a questionnaire and divided into two groups according to the positive family history of stone disease; group I comprised patients with a family history for urinary calculi and group II those without. Depending on the data obtained from questionnaires, all patients were evaluated in detail with respect to the age at the onset of the stone disease, stone passage and interventions over time, time to first recurrence (time interval between the onset of the disease and the first recurrence), number of total stone episodes and recurrence intervals. 1,595 patients suffering from urolithiasis with the mean age of 41.7 (14–69 years) were evaluated with respect to their past history of the disease. There were 437 patients in group I and 1,158 in group II. There was no statistically significant difference between the mean age value of two groups (P = 0.09). When both genders in group I were analyzed separately, female patients tended to have higher rate of family history positivity than males. Comparative evaluation of the age at the onset of the disease between the two groups did reveal that stone formation occured at younger ages in patients with positive family history [P = 0.01 (males), P = 0.01 (females)] and the mean age of onset of the disease was lower in males than females in group I (P = 0.01). Patients in group I had relatively more stone episodes from the onset of the disease [P < 0.01 (2–4 episodes), P < 0.01 (≥5 episodes)]. Male patients were associated with higher number of stone episodes (P = 0.01). Mean time interval between recurrences was noted to be significantly shorter in group I patients when compared with patients in group II [P < 0.01 (males), P = 0.02 (females)]. In conclusion, our results showed that urinary stone formation may occur at younger ages and that the frequency of symptom episodes may be higher in patients with a positive family history. We believe that the positive family history for urinary stone disease could give us valuable information concerning the onset as well as the severity of the disease

Barriers and facilitators to implementing community outreach work, and inter-professional collaboration with regional partners

Abstract : Objective. Community outreach workers support individuals in accessing the health and community services they require through various forms of proximity approaches. Even though community outreach has been available in the province of Quebec (Canada) for the past 40 years, it is still difficult to implement and sustain, especially with families of young children. The aim of this study was to document barriers and facilitators to implementing community outreach practices, and to describe how such workers collaborate with sectoral (e.g. health care) and inter-sectoral (e.g. municipalities, community organizations, schools) partners. Methodology. We performed a content analysis on 55 scientific and grey literature documents, and transcriptions of 24 individual interviews and 3 focus groups with stakeholders including parents, community outreach workers, health care employees, and inter-sectoral partners. Results. This study reveals four categories of barriers and facilitators to the implementation of community outreach work (i.e. organizational factors, nature of the work and worker-related factors, family-related factors, external factors). With regards to collaboration, community outreach workers deal with various partners. Good inter-professional collaboration is achieved through positive interactions and communication, shared or co-developed activities for the families, co-intervention with families, and strategies to enhance role awareness and inter-sectoral meetings. Conclusion. Results highlighted that many factors interact and can either influence, positively or negatively, the opportunity to implement community outreach work. The collaborative practices identified may help to maximize facilitators and overcome barriers. Advocacy and a better understanding of how to integrate community outreach work within health services while maintaining the workers’ flexibility are needed to sustain this practice

Structural Extremes in a Cretaceous Dinosaur

Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic

Cluster Lenses

Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining to cluster formation and evolution, as well as constraining the nature of dark matter; (ii) the study of the lensed objects - probing the properties of the background lensed galaxy population - which is statistically at higher redshifts and of lower intrinsic luminosity thus enabling the probing of galaxy formation at the earliest times right up to the Dark Ages; and (iii) the study of the geometry of the Universe - as the strength of lensing depends on the ratios of angular diameter distances between the lens, source and observer, lens deflections are sensitive to the value of cosmological parameters and offer a powerful geometric tool to probe Dark Energy. In this review, we present the basics of cluster lensing and provide a current status report of the field.Comment: About 120 pages - Published in Open Access at: http://www.springerlink.com/content/j183018170485723/ . arXiv admin note: text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

Systematic review of interventions for children with Fetal Alcohol Spectrum Disorders

<p>Abstract</p> <p>Background</p> <p>Children with Fetal Alcohol Spectrum Disorders (FASD) may have significant neurobehavioural problems persisting into adulthood. Early diagnosis may decrease the risk of adverse life outcomes. However, little is known about effective interventions for children with FASD. Our aim is to conduct a systematic review of the literature to identify and evaluate the evidence for pharmacological and non-pharmacological interventions for children with FASD.</p> <p>Methods</p> <p>We did an electronic search of the Cochrane Library, MEDLINE, EMBASE, PsychINFO, CINAHL and ERIC for clinical studies (Randomized controlled trials (RCT), quasi RCT, controlled trials and pre- and post-intervention studies) which evaluated pharmacological, behavioural, speech therapy, occupational therapy, physiotherapy, psychosocial and educational interventions and early intervention programs. Participants were aged under 18 years with a diagnosis of a FASD. Selection of studies for inclusion and assessment of study quality was undertaken independently by two reviewers. Meta-analysis was not possible due to diversity in the interventions and outcome measures.</p> <p>Results</p> <p>Twelve studies met the inclusion criteria. Methodological weaknesses were common, including small sample sizes; inadequate study design and short term follow up. Pharmacological interventions, evaluated in two studies (both RCT) showed some benefit from stimulant medications. Educational and learning strategies (three RCT) were evaluated in seven studies. There was some evidence to suggest that virtual reality training, cognitive control therapy, language and literacy therapy, mathematics intervention and rehearsal training for memory may be beneficial strategies. Three studies evaluating social communication and behavioural strategies (two RCT) suggested that social skills training may improve social skills and behaviour at home and Attention Process Training may improve attention.</p> <p>Conclusion</p> <p>There is limited good quality evidence for specific interventions for managing FASD, however seven randomized controlled trials that address specific functional deficits of children with FASD are underway or recently completed.</p

Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration