Giant pop-ins and amorphization in germanium during indentation

Sudden excursions of unusually large magnitude (>1 μm), “giant pop-ins,” have been observed in the force-displacement curve for high load indentation of crystalline germanium(Ge). A range of techniques including Raman microspectroscopy, focused ion-beam cross sectioning, and transmission electron microscopy, are applied to study this phenomenon. Amorphous material is observed in residual indents following the giant pop-in. The giant pop-in is shown to be a material removal event, triggered by the development of shallow lateral cracks adjacent to the indent. Enhanced depth recovery, or “elbowing,” observed in the force-displacement curve following the giant pop-in is explained in terms of a compliant response of plates of material around the indent detached by lateral cracking. The possible causes of amorphization are discussed, and the implications in light of earlier indentation studies of Ge are considered

Bumblebees of the Azores (Apidae: Bombus)

Bombus terrestris and Bombus pratorum were found for the first time in the Azores in 2005. Until then Bombus ruderatus was the only bumblebee species known from this group of nine midAtlantic islands. The identity of B. terrestris was confirmed by DNA barcoding

The shape of memory in temporal networks

Temporal networks are widely used models for describing the architecture of complex systems. Network memory -- that is the dependence of a temporal network's structure on its past -- has been shown to play a prominent role in diffusion, epidemics and other processes occurring over the network, and even to alter its community structure. Recent works have proposed to estimate the length of memory in a temporal network by using high-order Markov models. Here we show that network memory is inherently multidimensional and cannot be meaningfully reduced to a single scalar quantity. Accordingly, we introduce a mathematical framework for defining and efficiently estimating the microscopic shape of memory, which fully characterises how the activity of each link intertwines with the activities of all other links. We validate our methodology on a wide range of synthetic models of temporal networks with tuneable memory, and subsequently study the heterogeneous shapes of memory emerging in various real-world networks.Comment: 35 pages (5 main, 30 supplementary), 14 figures (3 main, 11 supplementary), 3 tables (all supplementary), uses tikz-network.sty and tikz_network.p

Weed control and overstory reduction improve survival and growth of under‐planted oak and hickory seedlings

Weed control and overstory reduction are important silvicultural treatments for improving survival and growth of under‐planted oak and hickory seedlings. Mast‐producing trees in the bottomland forests of the blackland prairie and Post Oak Savannah ecoregions of Texas have declined in abundance. Oaks and hickories have been replaced by more shade‐tolerant species, including green ash (Fraxinus pennsylvanica Marshall) and sugarberry (Celtis laevigata Willd.), which do not produce significant hard mast for priority wildlife species. A split‐plot experiment design was installed on three sites at Richland Creek Wildlife Management Area in Freestone County, Texas, studying the effects of canopy coverage and competition control on survival and growth of bur oak (Quercus macrocarpa Michx.), Shumard oak (Quercus shumardii Buckl.), and pecan (Carya illinoinensis (Wagenh.) K. Koch) seedlings. Uprooting by hogs shortly after planting resulted in greater than 90% mortality of pecan on the two lower elevation sites. Year one survival of Shumard oak was significantly higher than bur oak. However, bur oak was more preferred by hogs than Shumard oak. Year one growth of bur oak was significantly greater than Shumard oak. Severe flooding during the second growing season caused complete mortality on the lower two sites. None of the species were well suited to such prolonged (3–4 months) inundation as seedlings. On the remaining site, density reduction and weed‐barrier mats improved growth and survival while herbaceous weed control with herbicides actually reduced both growth and survival

Using Mobile Phones to Improve Vaccination Uptake in 21 Low- and Middle-Income Countries: Systematic Review

Background: The benefits of vaccination have been comprehensively proven, however disparities in coverage persist due to poor health system management, limited resources and parental knowledge and attitudes. Evidence suggests that health interventions that engage local parties in communication strategies improve vaccination uptake. As mobile technology is widely used to improve health communication, mobile health (mHealth) interventions might be used to increase coverage. Objective: To conduct a systematic review of the available literature on the use of mHealth to improve vaccination in low and middle income countries with large numbers of unvaccinated children. Methods: In February 2017, MEDLINE, Scopus and Web of Science, and three health organization websites; Communication Initiative Network, TechNet-21, and PATH, were searched to identify mHealth intervention studies on vaccination uptake in 21 countries. Results: Ten peer-reviewed studies and eleven studies from white or grey literature were included. Nine took place in India, three in Pakistan, two each in Malawi and Nigeria, and one each in Bangladesh, Zambia, Zimbabwe and Kenya. Ten peer-reviewed studies and seven white/grey studies demonstrated improved vaccination uptake after interventions, including appointment reminders, mobile phone apps and pre-recorded messages. Conclusions: While the potential for mHealth interventions to improve vaccination coverage seems clear, the evidence for such interventions is not. The dearth of studies in countries facing the greatest barriers to immunization impedes the prospects for evidence-based policy and practice in these settings.The study was funded by the Medical Research Council, British Heart Foundation, and Homerton College, Cambridge

Rapid one-step biotinylation of biological and non-biological surfaces

We describe a rapid one-step method to biotinylate virtually any biological or non-biological surface. Contacting a solution of biotin-spacer-lipid constructs with a surface will form a coating within seconds on non-biological surfaces or within minutes on most biological membranes including membrane viruses. The resultant biotinylated surface can then be used to interact with avidinylated conjugates, beads, vesicles, surfaces or cells

Nanoindentation-induced phase transformation in relaxed and unrelaxed ion-implanted amorphous germanium

We have investigated nanoindentation-induced plastic deformation in amorphousgermanium (a-Ge) prepared by high-energy self-ion implantation. Using cross-sectional transmission electron microscopy, micro-Raman spectroscopy, and force-displacement curve analysis, we find strong evidence for a pressure-induced metallic phase transformation during indentation. Crystalline diamond-cubic Ge-I is observed in residual indents. Relaxed and unrelaxed structural states of a-Ge exhibit similar behavior on loading, but transform at different pressures on unloading. Both forms are markedly softer mechanically than crystalline Ge. These results assist in furthering the understanding of the intriguing phenomenon known as “explosive crystallization.”We thank the Australian Research Council for funding support

Stress Hormones: A Link between Maternal Condition and Sex‐Biased Reproductive Investment

Abstract: In species where offspring fitness is sex‐specifically influenced by maternal reproductive condition, sex allocation theory predicts that poor‐quality mothers should invest in the evolutionarily less expensive sex. Despite an accumulation of evidence that mothers can sex‐specifically modulate investment in offspring in relation to maternal quality, few mechanisms have been proposed as to how this is achieved. We explored a hormonal mechanism for sex‐biased maternal investment by measuring and experimentally manipulating baseline levels of the stress hormone corticosterone in laying wild female European starlings (Sturnus vulgaris) and examining effects on sex ratio and sex‐specific offspring phenotype adjustment. Here we show that baseline plasma corticosterone is negatively correlated with energetic body condition in laying starlings, and subsequent experimental elevation of maternal baseline plasma corticosterone increased yolk corticosterone without altering maternal condition or egg quality per se. Hormonal elevation resulted in the following: female‐biased hatching sex ratios (caused by elevated male embryonic mortality), lighter male offspring at hatching (which subsequently grew more slowly during postnatal development), and lower cell‐mediated immune (phytohemagglutinin) responses in males compared with control‐born males; female offspring were unaffected by the manipulation in both years of the study. Elevated maternal corticosterone therefore resulted in a sex‐biased adjustment of offspring quality favorable to female offspring via both a sex ratio bias and a modulation of male phenotype at hatching. In birds, deposition of yolk corticosterone may benefit mothers by acting as a bet‐hedging strategy in stochastic environments where the correlation between environmental cues at laying (and therefore potentially maternal condition) and conditions during chick‐rearing might be low and unpredictable. Together with recent studies in other vertebrate taxa, these results suggest that maternal stress hormones provide a mechanistic link between maternal quality and sex‐biased maternal investment in offspring

Rate-dependent phase transformations in nanoindented germanium

There is considerable controversy over the deformation behavior of germanium(Ge) under nanoindentation using a sharp diamond tip, with a diverse range of observations that suggest competing mechanisms. Here we show the deformation mechanism of Ge can be controlled by the rate of applied load. Loading rate is varied over three orders of magnitude using depth-sensing nanoindentation. At slow loading rates, shear-induced plasticity is observed. At rapid loading rates (>100 mN s¯¹), pressure-induced phase transformations are detected by ex situ micro-Raman spectroscopy and transmission electron microscopy. This switch in the deformation mechanism is due to the differing rate sensitivities of the respective deformation modes, shear-induced plasticity or pressure-induced phase transformation

The effects of anxiety and situation-specific context on perceptual–motor skill: a multi-level investigation

We examined the effects of anxiety and situation- specific contextual information on attentional, interpretational, and behavioural processes underpinning perceptual– motor performance as proposed by Nieuwenhuys and Oudejans (2012) using an in situ task. Twelve skilled cricket batsmen played against a skilled spin bowler under conditions manipulated to induce low and high levels of anxiety and the presence of low and high levels of situation-specific context. High anxiety decreased the number of good bat– ball contacts, while high levels of situation-specific context increased the number of times the ball was missed. When under high anxiety, participants employed significantly more fixations of shorter duration to more locations, but the effects of anxiety were restricted to the attentional level only. Situation-specific context affected performance and behavioural measures but not anxiety, cognitive load or perceptual–cognitive processes, suggesting that performance is influenced through different mechanisms from anxiety that are independent of working memory load