Nearly uniform sampling of crystal orientations

International audienceA method is presented for generating nearly uniform distributions of three-dimensional orientations in the presence of symmetry. The method is based on the Thomson problem, which consists in finding the configuration of minimal energy of N electrons located on a unit sphere – a configuration of high spatial uniformity. Orientations are represented as unit quaternions, which lie on a unit hypersphere in four-dimensional space. Expressions of the electrostatic potential energy and Coulomb's forces are derived by working in the tangent space of orientation space. Using the forces, orientations are evolved in a conventional gradient-descent optimization until equilibrium. The method is highly versatile as it can generate uniform distributions for any number of orientations and any symmetry, and even allows one to prescribe some orientations. For large numbers of orientations, the forces can be computed using only the close neighbourhoods of orientations. Even uniform distributions of as many as 10 6 orientations, such as those required for dictionary-based indexing of diffraction patterns, can be generated in reasonable computation times. The presented algorithms are implemented and distributed in the free (open-source) software package Neper

Les fleurs rares réintroduites

En lien avec l’émergence récente d’une nouvelle discipline, la biologie de la conservation, un nouvel outil de conservation a été exploré par la communauté scientifique : les réintroductions de taxons rares ou menacés dans la nature. Cet article, qui s’appuie sur deux exemples de réintroductions d’espèces végétales menées en France, illustre comment la rationalité de tels projets, souvent présentés par leurs promoteurs comme relevant de l’inscription des taxons retenus au rang des « espèces protégées », se révèle davantage construite socialement sur des critères techniques, stratégiques, et communicationnels. Elles relèvent en ce sens soit d’une négociation, soit de la cristallisation d’objectifs variés. L’observation de la construction de la fleur réintroduite permet alors d’observer les influences réciproques entre des réseaux locaux, ancrés dans les territoires, et des réseaux globaux.Following the emergence of a new discipline, conservation biology, a new conservation tool has been investigated by the scientific community: the reintroduction of rare or endangered taxa. This article, which deals with two examples of the reintroduction of plant species carried out in France, illustrates how the rationality of such projects, frequently presented by their promoters as relying on the inscription of chosen taxa on lists of "protected species", turns out more to be socially constructed according to technical, strategic and communicational criteria. In this sense they are the products either of negotiation or crystallisation of various objectives. The observation of the construction of the reintroduced flower therefore allows us to observe the reciprocal influences between local networks and global networks

DEFORMATION MICROSTRUCTURE AND TEXTURE EVOLUTION OF {110}<112> Al-0.3wt.%Mn SINGLE CRYSTALS COMPRESSED IN A CHANNEL-DIE

Publié suite au congrès : 10th French-Polish Joint Symposium on Inhomogeneity of Deformation in Materials Univ Paris Sud, Orsay, FRANCE, MAY 19-20, 2008 Pas de DOI : http://www.imim.pl/files/archiwum/Vol1_2009/65-74.pdfInternational audienceCrystal subdivision patterns of microbands have been extensively reported but mostly by studies on only one section, using either TEM or SEM-EBSD. To better correlate substructure with slip patterns a systematic study of the 3D deformation microstructure in a deformed single crystal (i.e. over the 3 perpendicular surfaces) has been carried out. The microstructure and microtexture evolutions during plane strain deformation of high purity single crystals of Al-0.3%wt.Mn alloy with initial ideal and near-brass{110} orientations were characterised by TEM and high resolution FEG-SEM/EBSD after strains of 0.15 and 0.56. These two different techniques enable one to examine the crystal subdivision deformation pattern at different microscopic scales, on the 3 orthogonal sections, i.e. perpendicular to the nominal , and crystallographic directions. Particular attention is paid to a comparison of the microband orientations with the expected slip traces of the 2 active slip systems on all 3 surfaces. It is concluded that the microband boundary alignment corresponds very well to the traces of the crystallographic {111} planes, on which most of the slip occurs

1-Benz­yloxy-4-(2-nitro­ethen­yl)benzene

The title compound, C15H13NO3, crystallizes with three independent mol­ecules per asymmetric unit (Z′ = 3). One of these mol­ecules is found to have a configuration with a greater twist between its two aromatic rings than the other two [compare 70.26 (13) and 72.31 (12)° with 84.22 (12)°]. There are also differences in the number and nature of the weak inter­molecular C—H⋯O contacts formed by each of the three mol­ecules

Achieving High Coverage in Rwanda\u27s National Human Papillomavirus Vaccination Programme

Problem: Virtually all women who have cervical cancer are infected with the human papillomavirus (HPV). Of the 275000 women who die from cervical cancer every year, 88% live in developing countries. Two vaccines against the HPV have been approved. However, vaccine implementation in low-income countries tends to lag behind implementation in high-income countries by 15 to 20 years. Approach: In 2011, Rwanda’s Ministry of Health partnered with Merck to offer the Gardasil HPV vaccine to all girls of appropriate age. The Ministry formed a “public–private community partnership” to ensure effective and equitable delivery. Local setting: Thanks to a strong national focus on health systems strengthening, more than 90% of all Rwandan infants aged 12–23 months receive all basic immunizations recommended by the World Health Organization. Relevant changes: In 2011, Rwanda’s HPV vaccination programme achieved 93.23% coverage after the first three-dose course of vaccination among girls in grade six. This was made possible through school-based vaccination and community involvement in identifying girls absent from or not enrolled in school. A nationwide sensitization campaign preceded delivery of the first dose. Lessons learnt: Through a series of innovative partnerships, Rwanda reduced the historical two-decade gap in vaccine introduction between high- and low-income countries to just five years. High coverage rates were achieved due to a delivery strategy that built on Rwanda’s strong vaccination system and human resources framework. Following the GAVI Alliance’s decision to begin financing HPV vaccination, Rwanda’s example should motivate other countries to explore universal HPV vaccine coverage, although implementation must be tailored to the local context

Comparison of bioactivities, binding properties and intra-follicular levels of bovine follistatins

Five isoforms of follistatin (FST) (Mr 31, 33, 35, 37, 41kDa) were purified from bovine follicular fluid (bFF). Comparison of their activin- and heparan sulphate proteoglycan (HSP)-binding properties and bio-potencies in neutralization of activin-A action in vitro revealed that all five isoforms bound activin-A, but with different affinities. Only the 31kDa isoform (FST-288) bound to HSP. FST-288 also showed the greatest biopotency with 35 and 41kDa isoforms being least potent. To determine whether bovine follicle development is associated with changing intrafollicular FST and activin profiles, we analyzed bFF from dominant (DF) and subordinate (SF) follicles collected at strategic times during a synchronized estrous cycle. Total FST, activin-A and activin-AB were measured by immunoassay while individual FST isoforms were quantified by immunoblotting. Follicle diameter was positively correlated with estrogen:progesterone ratio (r=0.56) in bFF but negatively correlated with activin-A (r=-0.34), activin-AB (r=-0.80) and ‘total’ FST (r=-0.70) levels. Follicle diameter was positively correlated with abundance of the 41 kDa isoform (r=0.59) but negatively correlated with abundance of 33 and 31 kDa isoforms (r=-0.56, -0.41). Both follicle status (DF vs SF) and cycle stage affected total FST, activin-A, activin-B levels while follicle status, but not cycle stage, affected abundance of 41, 37, 33 and 31kDa FST isoforms. Collectively, these findings indicate that intrafollicular FST isoforms that differ in their ability to bind and neutralise activins and associate with cell-surface proteoglycans, show divergent changes during follicle development. Enhanced FST production may have an important negative role, either directly or via inhibition of the positive effects of activins, on follicle growth and function during follicular waves

Preparing for a Changing Climate: The State of Adaptation Planning in Maine’s Coastal Communities

Climate change is having a range of impacts on Maine’s coastal communities, impacts that will be further exacerbated by increased coastal flooding, storm events, and a warming Gulf of Maine. To better understand the status of adaptation planning by Maine coastal communities, we conducted a survey and in-depth interviews with decision makers from coastal communities. We found that communities are addressing the effects of climate change and have moved towards specific implementation strategies. Adaptation planning to date includes incorporation of climate change impacts in comprehensive planning and addressing impacts on roads, culverts, and waterfront infrastructure. Respondents indicated the need for more specific data on the direct impacts of climate change in their communities over the next two years. They identified a preference for spatial data and interactive websites, followed by support from technical experts. Although the majority of respondents had an understanding of the physical vulnerabilities their communities face, they identified a need for increased resources to assess social vulnerability impacts. Additionally, communities face challenges in identifying appropriate funding sources that match identified needs. Adaptation planning processes are often stymied by the lack of dedicated funding that enables coastal communities to be proactive in addressing the physical and social impacts of climate change

HTT is a repressor of ABL activity required for APP induced axonal growth

ABL tyrosine kinase activity controls several aspects of development including axon patterning. Amyloid precursor protein (APP) is linked to Alzheimer's disease and previous work established that ABL is a downstream effector in an Appl, the Drosophila App ortholog, signaling pathway which modulates axon outgrowth in the mushroom bodies (MBs), the fly memory center. Here we show that Abl is required for the MB neuron axonal growth. Importantly, both Abl overexpression and lack of expression produce a similar phenotype in the MBs indicating the necessity of tightly regulating ABL activity. We find that the fly huntingtin protein (HTT), the homolog of the protein involved in Huntington's disease, behaves genetically as a repressor of ABL activity. Supporting this, FRET-based measurements of in vivo ABL activity in the MBs reveal a clear increase in its activity when HTT levels are reduced. Thus, in addition to its many other reported roles, HTT acts as a negative regulator of ABL activity, at least in the MBs, to maintain its appropriate physiological levels necessary for axon growth.