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The Q resolution in Bonse–Hart double‐crystal diffractometers is determined for a given Bragg angle by the value of the crystallographic structure factor. To date, the reflections Si 220 or Si 111 have been used exclusively in neutron scattering, which provide resolutions for triple‐bounce crystals of about 2 × 10−5 Å−1 (FWHM). The Darwin width of the GaAs 200 reflection is about a factor of 10 smaller, offering the possibility of a Q resolution of 2 × 10−6 Å−1 provided crystals of sufficient quality are available. This article reports a feasibility study with single‐bounce GaAs 200, yielding a Q resolution of 4.6 × 10−6 Å−1, six times superior in comparison with a Si 220 setup. [ABSTRACT FROM AUTHOR]

∙ Here, we describe a new database, MaarjAM, that summarizes publicly available Glomeromycota DNA sequence data and associated metadata. The goal of the database is to facilitate the description of distribution and richness patterns in this group of fungi. ∙ Small subunit (SSU) rRNA gene sequences and available metadata were collated from all suitable taxonomic and ecological publications. These data have been made accessible in an open-access database (http://maarjam.botany.ut.ee). ∙ Two hundred and eighty-two SSU rRNA gene virtual taxa (VT) were described based on a comprehensive phylogenetic analysis of all collated Glomeromycota sequences. Two-thirds of VT showed limited distribution ranges, occurring in single current or historic continents or climatic zones. Those VT that associated with a taxonomically wide range of host plants also tended to have a wide geographical distribution, and vice versa. No relationships were detected between VT richness and latitude, elevation or vascular plant richness. ∙ The collated Glomeromycota molecular diversity data suggest limited distribution ranges in most Glomeromycota taxa and a positive relationship between the width of a taxon's geographical range and its host taxonomic range. Inconsistencies between molecular and traditional taxonomy of Glomeromycota, and shortage of data from major continents and ecosystems, are highlighted. [ABSTRACT FROM AUTHOR]

Abstract: Climate warming is already influencing plant migration in different parts of the world. Numerous models have been developed to forecast future plant distributions. Few studies, however, have investigated the potential effect of warming on the reproductive output of plants. Understorey forest herbs in particular, have received little attention in the debate on climate change impacts. This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seed mass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slow colonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400km latitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006 and 2008). This study design allowed us to isolate the effects of accumulated temperature (Growing Degree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seed sowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally, we disentangled correlations between the different reproductive traits of A. nemorosa along the latitudinal gradient. We found a clear positive relationship between accumulated temperature and seed and seedling traits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient. Seed mass and seedling mass, for instance, increased by 9.7% and 10.4%, respectively, for every 1000°Ch increase in GDH. We also derived strong correlations between several seed and seedling traits both under field conditions and in incubators. Our results indicate that seed mass, incubator-based germination percentage (Germ%Inc) and the output of germinable seeds (product of number of seeds and Germ%Inc divided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes) provide valuable proxies to parameterize key population processes in models. We conclude that (1) climate warming may have a pronounced positive impact on sexual reproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit from including the temperature sensitivity of key seed traits and population processes. [Copyright &y& Elsevier]

Available experimental investigations on the effect of the aggregate-paste 'interfacial transition zone' (ITZ) on mass transport properties of cement-based materials appear to be ambiguous. While some studies have found a deleterious effect of the ITZ, results from others seem to suggest otherwise. The present study examines the relative influences of ITZ and microcracking on the oxygen diffusivity, oxygen permeability and water sorptivity, to further enhance understanding of the links between microstructure and transport properties. Specimens of several neat cement pastes, mortars and concretes were prepared and tested. Variables include water/cement (w/c) ratio (0·3 and 0·5), binder type (CEM I and CEM II with 8% silica fume), curing period (3 and 90 days), aggregate volume fraction (0-70%) and preconditioning temperature (50°C and 105°C). 105°C drying was adapted to induce microcracking. Backscattered electron microscopy and image analysis were applied to characterise the microstructure, in particular the microcracks. It was observed that in all cases, the transport properties of mortars decreased with increasing ITZ fraction. Permeability was far more sensitive to the presence of microcracking and changes in total porosity, compared with diffusivity or sorptivity. However, no critical threshold sand content linked to an ITZ percolation effect was found, even in the deliberately damaged samples. Concretes have about the same diffusivity and sorptivity, but significantly higher permeability than mortars with the same volume fraction of aggregate, despite a lower ITZ fraction. It is argued that the higher permeability of concrete is attributable to more microcracking, and because the microcracks and paste are less tortuous than the equivalent mortar. It is also shown that conventional permeability testing is affected by the sample thickness-to-maximum aggregate size ratio, which may be another factor explaining the disparity between the measured permeability of concretes and mortars. [ABSTRACT FROM AUTHOR]

As treatment options have improved, there has been a significant increase in the life expectancy of HIV-infected children and adolescents. For most adolescents, the time comes when it is appropriate to transition from pediatric care to an adult or community-based provider. In response to a program closure, a transition readiness scale was developed. A total of 39 caregivers of HIV-infected youth (ages 10-18) and 12 youth over the age of 18 years were interviewed at two time points. Barriers associated with transition were identified and addressed between visits. Transition readiness improved and state anxiety decreased significantly from the first time point to the last visit (approximately 7 months later). Not having a home social worker was the most reported concern/need identified. Barriers to transition and interventions utilized to assist with transitioning care are discussed. [ABSTRACT FROM AUTHOR]

The Family Ties Project (FTP) is a multi-agency, collaborative, federally funded demonstration project whose mission is to promote and preserve the well-being of District of Columbia (DC) children, youth, and families affected by HIV/AIDS by working with parents and caregivers to plan for the future care of their children. FTP was first funded in 1996 through the federal Administration for Children, Youth and Families (ACYF) as part of a national grant program to reduce the burden of infants and children abandoned or orphaned as the result of AIDS related illnesses. This article demonstrates the use of timelines in clinical practice. Timelines of the permanency planning process of three families who experienced a maternal death are presented to help illustrate the similarities and differences in the process for each of these families. Additionally, the authors discuss the implications for social work practice as they relate to client/family engagement, length of intervention, interdisciplinary collaboration within the HIV/AIDS service delivery system, and the use of timelines as a clinical tool. [ABSTRACT FROM AUTHOR]

Pattern of native vegetation, distribution of alien species and variation of environmental parameters were studied in mountain grasslands in a lithologically homogeneous Córdoba mountain range in Central Argentina. CCA showed that altitude was the most important factor determining the compositional variation of the vegetation, with soil nutrient status and stoniness as additional factors. Short-grass communities, associated with the driest habitats on plateaus, showed higher small-scale native species richness than wet-turf communities in valleys and tall-grass communities on slopes. Species richness was negatively correlated with soil parameters that indicate nutrient status and water availability. Also, there was a negative correlation between soil Ca-and Mg- content and richness. High native species richness coincided with high alien species richness. When smaller units -- community types -- were considered, it became evident that within short-grass vegetation,the three most species-rich community types contained significant numbers of alien species, while the other two did not. Even within one community type, the same quadrats that contained the highest number of native species, were also characterized by the highest numbers of alien species. Evidently, the same mechanism was responsible for high richness of both native and alien species. Alien species were distinguished by a greater proportion of annuals and prostrate stoloniferous plants, by lower palatability and by smaller proportion of zoochory. DCA ordination of quadrats on the basis of plant traits as attributes resulted in a clear distinction of three main vegetation types. Short-grass vegetation was distinguished by a predomination of late flowering species, tall-grass vegetation by the presence of high herbaceous... [ABSTRACT FROM AUTHOR]

Variation in small-scale plant species richness was examined betweentwenty discrete sites of calcareous alvar grasslands in western Estonian coastal area. This community type is very species rich at the small-scale. The pattern of diversity has often been explained by variation in ecological conditions which makes it possible to avoid competitive exclusion. Here we test an alternative species pool hypothesis.The species pool was defined as the set of species present in a community, but excluding all those species whose presence may be connected with exceptional environmental conditions for this community. MonteCarlo modelling was used to determine the strengths of the relationships between the non-independent variables: richness vs species pool and average shoot density vs richness. Site age was characterized by its elevation above sea level, since there is a continuous land uplift in the study area. Species richness was positively correlated to the size of the species pool, community age and vegetation density. We conclude that historical processes on both the regional and local levels, which determine the arrival of any particular species to a target community, and not environmental heterogeneity, are responsible forthe variations in species richness between communities of this type. [ABSTRACT FROM AUTHOR]

In order to understand the variation of Estonian calcareous thin-soil grasslands on Ordovician or Silurian limestone (alvars), 58 stands,distributed over the whole alvar region of Estonia, were described and clustered numerically using TABORD. Alvars are characterized by a high species richness. These mainly semi-natural communities have mostly developed after clear-cutting of forests. Grazing by domestic animals and removal of woody plants is needed for their maintenance. Primary (natural) alvar grasslands are found in a few places in coastal regions or in areas with thin-soil on monolithic bedrock. In data processing a whole stand, described by several small releves, was used in the classification as one description, including species frequencies as a quantitative measure. Seven clusters were separated and their configuration checked in a PCA-ordination. The resulting classification agreed with the previous `rough' classification. Both geographicaland ecological factors were related with the clustering and the ordination. The broad classification units, suggested for Estonian alvar grasslands, were quite similar to the ones described earlier for alvar vegetation on Oland, Sweden. Clusters differed in their species richness, environmental conditions and life-form spectra. Differences inspecies richness were defined by regional species pools. Compared toearlier surveys, only a small fraction of alvars still remains in Estonia. Active conservation, i.e. suitable management is needed to protect the still surviving valuable plant communities. The present study can provide guidelines on how to protect and manage different typesof alvars in Estonia. [ABSTRACT FROM AUTHOR]

Abstract: The catalyst layer is one of the key components of PEMFCs. As the electrochemical reaction occurs at the three-phase interface of the catalyst layer, it is necessary to investigate the hydrophobicity and/or hydrophilicity properties of catalyst layers, which have a large impact on the water transport and even on the performance of the PEMFC. In this paper, time dependent contact angle measurements and porosity analyses have been performed to characterize the catalyst-coated membranes. For the first time, environmental scanning electron microscopy (ESEM) has been used to measure the hydrophilicity and hydrophobicity in the catalyst layer microstructure. The micro-contact angle distribution is given based on the microstructure. It shows a micro-scale hydrophobicity and hydrophilicity study, especially for an inhomogenous material. By means of conventional time-dependent contact angle measurements, porosity measurements and micro-contact angle measurements by ESEM, the hydrophobicity and hydrophilicity of catalyst-coated membranes have been investigated. Useful information has been gained to assist the understanding of catalyst layers from catalyst-coated membranes. [Copyright &y& Elsevier]