Ultra-strong Adhesion of Graphene Membranes

As mechanical structures enter the nanoscale regime, the influence of van der Waals forces increases. Graphene is attractive for nanomechanical systems because its Young's modulus and strength are both intrinsically high, but the mechanical behavior of graphene is also strongly influenced by the van der Waals force. For example, this force clamps graphene samples to substrates, and also holds together the individual graphene sheets in multilayer samples. Here we use a pressurized blister test to directly measure the adhesion energy of graphene sheets with a silicon oxide substrate. We find an adhesion energy of 0.45 \pm 0.02 J/m2 for monolayer graphene and 0.31 \pm 0.03 J/m2 for samples containing 2-5 graphene sheets. These values are larger than the adhesion energies measured in typical micromechanical structures and are comparable to solid/liquid adhesion energies. We attribute this to the extreme flexibility of graphene, which allows it to conform to the topography of even the smoothest substrates, thus making its interaction with the substrate more liquid-like than solid-like.Comment: to appear in Nature Nanotechnolog

The impact of helmets on motorcycle head trauma at a tertiary hospital in Jamaica

<p>Abstract</p> <p>Background</p> <p>Although the Jamaica road traffic act mandates motorcycle riders to wear approved helmets, opponents suggest that the local road conditions obviate any benefits from helmet use that have been proven in Developed countries. They suggest that the narrow, winding, poorly surfaced, congested local highways do not allow motorcyclists to sustain high velocity travel. The accidents then tend to occur at lower speeds and are accompanied by less severe injuries. This study was carried out to determine the impact of helmet use on traumatic brain injuries from motorcycle collisions in patients admitted to a tertiary referral hospital in Jamaica.</p> <p>Methods</p> <p>A prospectively collected trauma registry maintained by the Department of Surgery at the University Hospital of the West Indies in Jamaica was accessed to identify all motorcycle collision victims from January 2000 to January 2007. The therapeutic outcomes of traumatic brain injuries were compared between helmeted and un-helmeted riders. The data was analyzed using SPSS Version 12.</p> <p>Results</p> <p>Of 293 motorcycle collision victims, 143 sustained brain injuries. There were 9 females (6.3%) with an average age of 23 +/- 7.3 years and 134 males (93.7%) at an average age of 33.4 +/- 11.2 years (mean +/- SD). Only 49 (34.3%) patients wore a helmet at the time of a collision. Helmet use at the time of a collision significantly reduced the severity of head injuries (28.6% vs 46.8%, P = 0.028) and the likelihood of sustaining intra-cranial lesions (26.5% vs 44.7%, P = 0.03) from head injuries.</p> <p>Conclusion</p> <p>Wearing a helmet at the time of a motorcycle collision reduces the severity of head injuries. However, the prevalence of helmet use at the time of a collision is unacceptably low.</p

A Unifying Framework for Evaluating the Predictive Power of Genetic Variants Based on the Level of Heritability Explained

An increasing number of genetic variants have been identified for many complex diseases. However, it is controversial whether risk prediction based on genomic profiles will be useful clinically. Appropriate statistical measures to evaluate the performance of genetic risk prediction models are required. Previous studies have mainly focused on the use of the area under the receiver operating characteristic (ROC) curve, or AUC, to judge the predictive value of genetic tests. However, AUC has its limitations and should be complemented by other measures. In this study, we develop a novel unifying statistical framework that connects a large variety of predictive indices together. We showed that, given the overall disease probability and the level of variance in total liability (or heritability) explained by the genetic variants, we can estimate analytically a large variety of prediction metrics, for example the AUC, the mean risk difference between cases and non-cases, the net reclassification improvement (ability to reclassify people into high- and low-risk categories), the proportion of cases explained by a specific percentile of population at the highest risk, the variance of predicted risks, and the risk at any percentile. We also demonstrate how to construct graphs to visualize the performance of risk models, such as the ROC curve, the density of risks, and the predictiveness curve (disease risk plotted against risk percentile). The results from simulations match very well with our theoretical estimates. Finally we apply the methodology to nine complex diseases, evaluating the predictive power of genetic tests based on known susceptibility variants for each trait

Time-trend of melanoma screening practice by primary care physicians: A meta-regression analysis

Objective. To assess whether the proportion of primary care physicians implementing full body skin examination (FBSE) to screen for melanoma changed over time. Methods. Meta-regression analyses of available data. Data Sources: MEDLINE, ISI, Cochrane Central Register of Controlled Trials. Results. Fifteen studies surveying 10,336 physicians were included in the analyses. Overall, 15%\u201382% of them reported to perform FBSE to screen for melanoma. The proportion of physicians using FBSE screening tended to decrease by 1.72% per year (P =0.086). Corresponding annual changes in European, North American, and Australian settings were 120.68% (P =0.494), 122.02% (P =0.044), and +2.59% (P =0.010), respectively. Changes were not influenced by national guide-lines. Conclusions. Considering the increasing incidence of melanoma and other skin malignancies, as well as their relative potential consequences, the FBSE implementation time-trend we retrieved should be considered a worrisome phenomenon

Stage at diagnosis for childhood solid cancers in Australia: A population-based study

BACKGROUND: Stage of cancer at diagnosis is one of the strongest predictors of survival and is essential for population cancer surveillance, comparison of cancer outcomes and to guide national cancer control strategies. Our aim was to describe, for the first time, the distribution of cases by stage at diagnosis and differences in stage-specific survival on a population basis for a range of childhood solid cancers in Australia. METHODS: The study cohort was drawn from the population-based Australian Childhood Cancer Registry and comprised children (<15 years) diagnosed with one of 12 solid malignancies between 2006 and 2014. Stage at diagnosis was assigned according to the Toronto Paediatric Cancer Stage Guidelines. Observed (all cause) survival was calculated using the Kaplan-Meier method, with follow-up on mortality available to 31 December 2015. RESULTS: Almost three-quarters (1256 of 1760 cases, 71%) of children in the study had localised or regional disease at diagnosis, varying from 43% for neuroblastoma to 99% for retinoblastoma. Differences in 5-year observed survival by stage were greatest for osteosarcoma (localised 85% (95% CI = 72%-93%) versus metastatic 37% (15%-59%)), neuroblastoma (localised 98% (91%-99%) versus metastatic 60% (52%-67%)), rhabdomyosarcoma (localised 85% (71%-93%) versus metastatic 53% (34%-69%)), and medulloblastoma (localised 69% (61%-75%) versus metastases to spine 42% (27%-57%)). CONCLUSION: The stage-specific information presented here provides a basis for comparison with other international population cancer registries. Understanding variations in survival by stage at diagnosis will help with the targeted formation of initiatives to improve outcomes for children with cancer

Estadificación del cáncer infantil para registros de base poblacional

La recogida de información internacional fiable sobre estadificación de cáncer infantil por los registros de cáncer de base poblacional es esencial para el análisis epidemiológico y la realización de comparaciones evaluativas internacionales explicativas de la incidencia y los resultados asistenciales. En 2014 la Unión International Contra el Cáncer (UICC), el Dana-Farber Cancer Institute y el Hospital for Sick Children de Toronto, convocaron una reunión de consenso para abordar la ausencia de información consistente en la estadificación del cáncer infantil en los registros de cáncer poblacionales. Para cada subconjunto de los grupos/subgrupos diagnósticos mayores de cáncer infantil, en la reunión fueron revisados todos los sistemas de estadificación específicos de cada enfermedad utilizados habitualmente y se recomendó el más adecuado para utilizar en los registros de cáncer de base poblacional. Los sistemas de estadificación recomendados están enumerados como Guías de Toronto para la Estadificación del Cáncer Pediátrico. Las Guías recomiendan sistemas de estadificación específicos para la Leucemia Linfoblástica Aguda, Leucemia Mieloblástica Aguda, Linfoma de Hodgkin, Linfoma no-Hodgkin, Neuroblastoma, Tumor de Wilms, Rabdomiosarcoma, Sarcomas de Tejidos Blandos no-Rabdomiosarcoma, Osteosarcoma, Sarcoma de Ewing, Retinoblastoma, Hepatoblastoma, Tumor de Células Germinales (Cáncer Testicular y Ovárico), Meduloblastoma y Ependimoma. En este texto se proporcionan descripciones detalladas de los sistemas de estadificación recomendados en las Guías, para ayudar a los registros poblacionales de cáncer a recoger información internacionalmente consistente y comparable sobre el estadio del cáncer infantil al diagnóstico utilizando los documentos clínicos disponibles. La viabilidad y validez de estas Guías se ha evaluado con éxito en la práctica2. Están avaladas por el proyecto Factores pronósticos TNM de la UICC y publicadas en la Clasificación TNM de los Tumores Malignos UICC 8ª edición

Simultaneous joint scaling test for several correlated traits

For generation mean analysis a simultaneous joint scaling test with several correlated traits is proposed. Scaling test for individual traits were compared with this test and in general were not independent and are relatively less efficient for the correlated traits situation. The two and three traits cases have been illustrated with real data

Trends in incidence of childhood cancer in Australia, 1983–2006

Cancer risk is increased substantially in adult kidney transplant recipients, but the long-term risk of cancer in childhood recipients is unclear. Using the Australian and New Zealand Dialysis and Transplant Registry, the authors compared overall and site-specific incidences of cancer after transplantation in childhood recipients with population-based data by using standardized incidence ratios (SIRs). Among 1734 childhood recipients (median age 14 years, 57% male, 85% white), 289 (16.7%) developed cancer (196 nonmelanoma skin cancers, 143 nonskin cancers) over a median follow-up of 13.4 years. The 25-year cumulative incidences of any cancer were 27% (95% confidence intervals 24-30%), 20% (17-23%) for nonmelanoma skin cancer, and 14% (12-17%) for nonskin cancer (including melanoma). The SIR for nonskin cancer was 8.23 (95% CI 6.92-9.73), with the highest risk for posttransplant lymphoproliferative disease (SIR 45.80, 95% CI 32.71-62.44) and cervical cancer (29.4, 95% CI 17.5-46.5). Increasing age at transplantation (adjusted hazard ratio [aHR] per year 1.10, 95% CI 1.06-1.14), white race (aHR 3.36, 95% CI 1.61-6.79), and having a functioning transplant (aHR 2.27, 95% CI 1.47-3.71) were risk factors for cancer. Cancer risk, particularly for virus-related cancers, is increased substantially after kidney transplantation during childhood