The time dependence dynamics of hydration water changes upon crossing T∗

We carry out a Nuclear Magnetic Resonance (NMR) spectroscopy study on the dynamics of lysozyme hydration water. We consider a hydration level corresponding to a single water monolayer. We investigate the thermodynamical region from 295K to 355 K, at temperatures below and above the “magic” temperature T∗ ≈ 320 K. In particular, we focus our attention on hydration water mean-square displacement (MSD) as a function of the diffusion time at different temperatures. Our results suggest the occurrence of a smooth anomalous diffusion from a sub-diffusive state (T < T ∗) to a super-diffusive one (T > T∗). These conclusions confirm the importance of the temperature T∗ as the border for water behavior

The local order of supercooled water in solution with LiCl studied by NMR proton chemical shift

We study by means of Nuclear Magnetic Resonance (NMR) spectroscopy the local order of water molecules in solution with lithium chloride at eutectic concentration. In particular, by measuring the proton chemical shift as a function of the temperature in the interval 203K < T < 320K, we observe a net change at about 235 K. We ascribe this result to the increase of the hydrogen bond interaction that on decreasing the temperature favors the formation of the network that characterizes the low density liquid phase of water. Furthermore, the Gaussian deconvolution of the NMR peak allows the investigation of the mutual difference between the chemical shift of water solvating lithium and chlorine individually. The thermal behavior of this quantity confirms previous results about the role of the temperature in the solvation mechanisms down to about 225 K. This temperature coincides with that of the so-called Widom line for water supporting the liquid-liquid transition hypothesis

Neutron Tomography at INES: First experimental results

A neutron tomography apparatus has been designed and installed at the Italian neutron experimental station (INES) at ISIS (UK). The instrument has a double aim: an additional opportunity for the INES users and a “bench test” for an instrument component that will be proposed for installation on some of the new neutron scattering instruments of Target Station 2 (TS2) of ISIS. Here, we present the first experimental results achieved with this apparatus

A narrative synthesis of the impact of primary health care delivery models for refugees in resettlement countries on access, quality and coordination

Introduction. Refugees have many complex health care needs which should be addressed by the primary health care services, both on their arrival in resettlement countries and in their transition to long-term care. The aim of this narrative synthesis is to identify the components of primary health care service delivery models for such populations which have been effective in improving access, quality and coordination of care. Methods. A systematic review of the literature, including published systematic reviews, was undertaken. Studies between 1990 and 2011 were identified by searching Medline, CINAHL, EMBASE, Cochrane Library, Scopus, Australian Public Affairs Information Service-Health, Health and Society Database, Multicultural Australian and Immigration Studies and Google Scholar. A limited snowballing search of the reference lists of all included studies was also undertaken. A stakeholder advisory committee and international advisers provided papers from grey literature. Only English language studies of evaluated primary health care models of care for refugees in developed countries of resettlement were included. Results: Twenty-five studies met the inclusion criteria for this review of which 15 were Australian and 10 overseas models. These could be categorised into six themes: service context, clinical model, workforce capacity, cost to clients, health and non-health services. Access was improved by multidisciplinary staff, use of interpreters and bilingual staff, no-cost or low-cost services, outreach services, free transport to and from appointments, longer clinic opening hours, patient advocacy, and use of gender-concordant providers. These services were affordable, appropriate and acceptable to the target groups. Coordination between the different health care services and services responding to the social needs of clients was improved through case management by specialist workers. Quality of care was improved by training in cultural sensitivity and appropriate use of interpreters. Conclusion: The elements of models most frequently associated with improved access, coordination and quality of care were case management, use of specialist refugee health workers, interpreters and bilingual staff. These findings have implications for workforce planning and training

The neutron irradiation module at the European Spallation Source ESS

The neutron Irradiation Module at the European Spallation Source will make use of the high intensity fast neutron spectrum to study the behaviour of the materials used in the facility, set within the ESS research and development program for the target station. By studying how these materials are affected by radiation, estimates of the material degradation in irrradiated bespoke samples will allow to optimise of the design and lifetime of regularly replaced target components. The general design and a set of results from the neutronics calculations, aimed at estimating proton and neutron flux distributions, displacement damage, heat deposition and activation for the radiological hazard analysis of the Irradiation Module, set within the Italian contributions to the ESS construction phase, are reported. © Published under licence by IOP Publishing Ltd

Repeated, Selection-Driven Genome Reduction of Accessory Genes in Experimental Populations

Genome reduction has been observed in many bacterial lineages that have adapted to specialized environments. The extreme genome degradation seen for obligate pathogens and symbionts appears to be dominated by genetic drift. In contrast, for free-living organisms with reduced genomes, the dominant force is proposed to be direct selection for smaller, streamlined genomes. Most variation in gene content for these free-living species is of “accessory” genes, which are commonly gained as large chromosomal islands that are adaptive for specialized traits such as pathogenicity. It is generally unclear, however, whether the process of accessory gene loss is largely driven by drift or selection. Here we demonstrate that selection for gene loss, and not a shortened genome, per se, drove massive, rapid reduction of accessory genes. In just 1,500 generations of experimental evolution, 80% of populations of Methylobacterium extorquens AM1 experienced nearly parallel deletions removing up to 10% of the genome from a megaplasmid present in this strain. The absence of these deletion events in a mutation accumulation experiment suggested that selection, rather than drift, has dominated the process. Reconstructing these deletions confirmed that they were beneficial in their selective regimes, but led to decreased performance in alternative environments. These results indicate that selection can be crucial in eliminating unnecessary genes during the early stages of adaptation to a specialized environment

Optimal Resting-Growth Strategies of Microbial Populations in Fluctuating Environments

Bacteria spend most of their lifetime in non-growing states which allow them to survive extended periods of stress and starvation. When environments improve, they must quickly resume growth to maximize their share of limited nutrients. Cells with higher stress resistance often survive longer stress durations at the cost of needing more time to resume growth, a strong disadvantage in competitive environments. Here we analyze the basis of optimal strategies that microorganisms can use to cope with this tradeoff. We explicitly show that the prototypical inverse relation between stress resistance and growth rate can explain much of the different types of behavior observed in stressed microbial populations. Using analytical mathematical methods, we determine the environmental parameters that decide whether cells should remain vegetative upon stress exposure, downregulate their metabolism to an intermediate optimum level, or become dormant. We find that cell-cell variability, or intercellular noise, is consistently beneficial in the presence of extreme environmental fluctuations, and that it provides an efficient population-level mechanism for adaption in a deteriorating environment. Our results reveal key novel aspects of responsive phenotype switching and its role as an adaptive strategy in changing environments

The Repeatability of Adaptive Radiation During Long-Term Experimental Evolution of Escherichia coli in a Multiple Nutrient Environment

Adaptive radiations occur when a species diversifies into different ecological specialists due to competition for resources and trade-offs associated with the specialization. The evolutionary outcome of an instance of adaptive radiation cannot generally be predicted because chance (stochastic events) and necessity (deterministic events) contribute to the evolution of diversity. With increasing contributions of chance, the degree of parallelism among different instances of adaptive radiations and the predictability of an outcome will decrease. To assess the relative contributions of chance and necessity during adaptive radiation, we performed a selection experiment by evolving twelve independent microcosms of Escherichia coli for 1000 generations in an environment that contained two distinct resources. Specialization to either of these resources involves strong trade-offs in the ability to use the other resource. After selection, we measured three phenotypic traits: 1) fitness, 2) mean colony size, and 3) colony size diversity. We used fitness relative to the ancestor as a measure of adaptation to the selective environment; changes in colony size as a measure of the evolution of new resource specialists because colony size has been shown to correlate with resource specialization; and colony size diversity as a measure of the evolved ecological diversity. Resource competition led to the rapid evolution of phenotypic diversity within microcosms. Measurements of fitness, colony size, and colony size diversity within and among microcosms showed that the repeatability of adaptive radiation was high, despite the evolution of genetic variation within microcosms. Consistent with the observation of parallel evolution, we show that the relative contributions of chance are far smaller and less important than effects due to adaptation for the traits investigated. The two-resource environment imposed similar selection pressures in independent populations and promoted parallel phenotypic adaptive radiations in all independently evolved microcosms