Shear-induced overaging in a polymer glass

A phenomenon recently coined as ``overaging'' implies a slowdown in the collective (slow) relaxation modes of a glass when a transient shear strain is imposed. We are able to reproduce this behavior in simulations of a supercooled polymer melt by imposing instantaneous shear deformations. The increases in relaxation times $\Delta \tau_{1/2}$ rise rapidly with deformation, becoming exponential in the plastic regime. This ``overaging'' is distinct from standard aging. We find increases in pressure, bond-orientational order and in the average energy of the inherent structures ($$) of the system, all dependent on the size of the deformation. The observed change in behavior from elastic to plastic deformation suggests a link to the physics of the ``jammed state''Comment: 5 pages including 5 figure

Catalytic constructive deoxygenation of lignin-derived phenols: new C-C bond formation processes from imidazole-sulfonates and ether cleavage reactions

Funding: UK Engineering and Physical Sciences Research Council (EPSRC)As part of a programme aimed at exploiting lignin as a chemical feedstock for less oxygenated fine chemicals, several catalytic C-C bond forming reactions utilising guaiacol imidazole sulfonate are demonstrated. These include the cross-coupling of a Grignard, a non-toxic cyanide source, a benzoxazole, and nitromethane. A modified Meyers reaction is used to accomplish a second constructive deoxygenation on a benzoxazole functionalised anisole.Publisher PDFPeer reviewe

Biphasic, Lyotropic, Active Nematics

We perform dynamical simulations of a two-dimensional active nematic fluid in coexistence with an isotropic fluid. Drops of active nematic become elongated, and an effective anchoring develops at the nematic-isotropic interface. The activity also causes an undulatory instability of the interface. This results in defects of positive topological charge being ejected into the nematic, leaving the interface with a diffuse negative charge. Quenching the active lyotropic fluid results in a steady state in which phase-separating domains are elongated and then torn apart by active stirring.Comment: 7 pages, 8 figure

EUS-Guided Pancreatic Cyst Ablation: a Clinical and Technical Review

Purpose of Review Pancreatic cystic lesions represent a growing public health dilemma, particularly as our population ages and cross-sectional imaging becomes more sensitive. Mucinous cysts carry a clinically significant risk of developing pancreatic cancer, which carries an extremely poor prognosis. Determining which cysts will develop cancer may be challenging, and surgical resection of the pancreas carries significant morbidity. The goal of this paper is to review the rationale for cyst ablation and discuss prior and current research on cyst ablation techniques and efficacy. Indications, contraindications, and factors related to optimal patient selection are outlined. Recent Findings Endoscopic ultrasound-guided chemoablation of pancreatic cysts has been performed in neoplastic cysts, with varying levels of efficacy. Safety concerns arose due to the risk of pancreatitis in alcohol-based treatments; however, the most recent data using a non-alcohol chemoablation cocktail suggests that ablation is effective without the need for alcohol, resulting in a significantly more favorable adverse event profile. Summary Endoscopic ultrasound-guided chemoablation of neoplastic pancreatic cysts is a promising, minimally invasive approach for treatment of cysts, with recent significant advances in safety and efficacy, suggesting that it should play a role in the treatment algorithm

Fathers, Divorce, and Child Custody

A great many fathers will have their fathering eliminated, disrupted, or vastly changed because they become divorced from the child’s mother. In fact, between 40% and 50% of marriages end in divorce (Cherlin, 2010). Although the divorce rate (measured as divorces per 1,000 people) is high by the standards prior to the late 1960s, it has actually fallen more than 30% since its peak in 1980. The decline in divorce rates in recent years has, however, been concentrated among the college-educated portion of the population; divorce rates among the less well educated may have even increased (Cherlin, 2010). But for both groups, divorce remains the most prevalent reason for changes in paternal parenting opportunities. For almost all divorced fathers (as well as for most mothers and children), divorce is a life-defining event, around which all other experiences are organized: before the divorce versus after the divorce. Although mothers’ parenting is generally changed by divorce, the revision to the parent-child interaction patterns is generally not as far-reaching as it is to fathers’ (Braver & Lamb, in press; Braver, Shapiro, & Goodman, 2005; Fabricius, Braver, Diaz, & Velez, 2010). The reason, of course, is the radical difference between the two parents’ custodial arrangements that typically occurs. As will be documented more precisely below, mothers generally become chief custodians of children, with fathers having visiting rights only. Although that situation has changed in recent years, due in large part to the fact that research has accumulated that illuminates the unintended negative consequences of that practice on fathers and children, it remains normative. Thus, no review of fathers and divorce can be complete or enlightening unless it also considers custody matters, as we do here

Burden of fetal alcohol syndrome in a rural West Coast area of South Africa

Background. Fetal alcohol syndrome (FAS) is common in parts of South Africa; rural residence is a frequently cited risk factor. We conducted a FAS school prevalence survey of an isolated rural community in a West Coast village of Western Cape Province, so obtaining the first directly measured rate, focusing specifically on a South African rural area, of FAS and partial FAS (PFAS). Methods. The study area (Aurora village), a community of about 2 500 people in a grain-producing region, has one primary school. All learners were eligible for study inclusion. Initial anthropometry screening was followed by a diagnostic stage entailing examination by a dysmorphologist for features of FAS, neurodevelopmental assessment, and an interview assessing maternal alcohol consumption. Results. Of 160 learners screened, 78 (49%) were screen-positive, of whom 63 (81%) were clinically assessed for FAS. The overall FAS/PFAS rate among the screened learners was 17.5% (95% confidence interval 12.0 - 24.2%), with 16 (10.0%) children having FAS and 12 (7.5%) PFAS. High rates of stunting, underweight and microcephaly were noted in all learners, especially those with FAS or PFAS. Five (18%) mothers of affected children were deceased by the time of assessment. Conclusion. We describe very high rates of FAS/PFAS in an isolated rural part of the Western Cape that is not located in a viticultural region. Our study suggests that the prevalence of FA S may be very high in isolated communities, or in particular hot-spots. It adds to the growing evidence that FAS/PFAS is a significant, and underestimated, health problem in South Africa. Expanded screening and surveillance programmes, and preventive interventions, are urgently needed

Indigenous wellbeing in Australia: evidence from HILDA

This study explores the subjective wellbeing of Indigenous Australians. Abstract Report focusses on mean levels of self-reported life satisfaction, inequality in life satisfaction within the Indigenous and non-Indigenous Australian populations, and the prevalence and severity of dissatisfaction with one’s life. Evidence on differences in the determinants of life satisfaction between Indigenous and non-Indigenous Australians is provided. Results indicate that Indigenous life satisfaction peaked in 2003 and has since declined. We also find that inequality in life satisfaction is greater for Indigenous than non-Indigenous Australians. Despite a downward trend in the level of dissatisfaction for non-Indigenous Australians, dissatisfaction among Indigenous Australians has remained relatively unchanged

The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

A free-electron like band has recently been observed in a monolayer of PTCDA (3,4,9,10-perylene tetracarboxylic dianhydride) molecules on Ag(111) by two-photon photoemission [Schwalb et al., Phys. Rev. Lett. 101, 146801 (2008)] and scanning tunneling spectroscopy [Temirov et al., Nature 444, 350 (2006)]. Using density functional theory calculations, we find that the observed free-electron like band originates from the Shockley surface state band being dramatically shifted up in energy by the interaction with the adsorbed molecules while it acquires also a substantial admixture with a molecular band

Estimating the Impact of State Policies and Institutions with Mixed-Level Data

Researchers often seek to understand the effects of state policies or institutions on individual behavior or other outcomes in sub-state-level observational units (e.g., election results in state legislative districts). However, standard estimation methods applied to such models do not properly account for the clustering of observations within states and may lead researchers to overstate the statistical significance of state-level factors. We discuss the theory behind two approaches to dealing with clusteringclustered standard errors and multilevel modeling. We then demonstrate the relevance of this topic by replicating a recent study of the effects of state post-registration laws on voter turnout (Wolfinger, Highton, and Mullin 2005). While we view clustered standard errors as a more straightforward, feasible approach, especially when working with large datasets or many cross-level interactions, our purpose in this Practical Researcher piece is to draw attention to the issue of clustering in state and local politics research.mixed-level data, voter turnout