X-ray polarization: General formalism and polarization analysis

The polarization of x-rays plays an outstanding role in experimental techniques such as non-resonant magnetic x-ray scattering and resonant x-ray scattering of magnetic and multipolar order. Different instrumental methods applied to synchrotron light can transform its natural polarization into an arbitrary polarization state. Several synchrotron applications, in particular in the field of magnetic and resonant scattering rely on the improvement in the signal/noise ratio or the deeper insight into the ordered state and the scattering process made possible through these polarization techniques. Here, we present the mathematical framework for the description of fully and partially polarized x-rays, with some applications such as linear x-ray polarization analysis for the determination of the scattered beam's polarization, and the Ge K-edge resonant scattering.Comment: 12 pages, 6 figures and 1 table. To be published in proceedings of the workshop "Resonant Elastic X-ray Scattering", Aussois, France (2011

Measuring Population Transmission Potential for HIV: An Alternative Metric of Transmission Risk in Men who have Sex with Men (MSM) in the US

Background Various metrics for HIV burden and treatment success [e.g. HIV prevalence, community viral load (CVL), population viral load (PVL), percent of HIV-positive persons with undetectable viral load] have important public health limitations for understanding disparities. Methods and Findings Using data from an ongoing HIV incidence cohort of black and white men who have sex with men (MSM), we propose a new metric to measure the prevalence of those at risk of transmitting HIV and illustrate its value. …See full text for complete abstract

The Comparability of Men Who Have Sex With Men Recruited From Venue-Time-Space Sampling and Facebook: A Cohort Study

Background: Recruiting valid samples of men who have sex with men (MSM) is a key component of the US human immunodeficiency virus (HIV) surveillance and of research studies seeking to improve HIV prevention for MSM. Social media, such as Facebook, may present an opportunity to reach broad samples of MSM, but the extent to which those samples are comparable with men recruited from venue-based, time-space sampling (VBTS) is unknown. Objective: The objective of this study was to assess the comparability of MSM recruited via VBTS and Facebook. Methods: HIV-negative and HIV-positive black and white MSM were recruited from June 2010 to December 2012 using VBTS and Facebook in Atlanta, GA. We compared the self-reported venue attendance, demographic characteristics, sexual and risk behaviors, history of HIV-testing, and HIV and sexually transmitted infection (STI) prevalence between Facebook- and VTBS-recruited MSM overall and by race. Multivariate logistic and negative binomial models estimated age/race adjusted ratios. The Kaplan-Meier method was used to assess 24-month retention. Results: We recruited 803 MSM, of whom 110 (34/110, 30.9% black MSM, 76/110, 69.1% white MSM) were recruited via Facebook and 693 (420/693, 60.6% black MSM, 273/693, 39.4% white MSM) were recruited through VTBS. Facebook recruits had high rates of venue attendance in the previous month (26/34, 77% among black and 71/76, 93% among white MSM; between-race P=.01). MSM recruited on Facebook were generally older, with significant age differences among black MSM (P=.02), but not white MSM (P=.14). … See full text for complete abstract

Lab-on-a-chip platforms based on highly sensitive nanophotonic Si biosensors for single nucleotide DNA testing

In order to solve the drawbacks of sensitivity and portability in optical biosensors we have developed ultrasensitive and miniaturized photonic silicon sensors able to be integrated in a "lab-on-a-chip" microsystem platform. The sensors are integrated Mach-Zehnder interferometers based on TIR optical waveguides (Si/SiO2/Si3N4) of micro/nanodimensions. We have applied this biosensor for DNA testing and for detection of single nucleotide polymorphisms at BRCA-1 gene, involved in breast cancer development, without target labeling. The oligonucleotide probe is immobilized by covalent attachment to the sensor surface through silanization procedures. The hybridization was performed for different DNA target concentrations showing a lowest detection limit at 10 pM. Additionally, we have detected the hybridization of different concentrations of DNA target with two mismatching bases corresponding to a mutation of the BRCA-1 gene. Following the way of the lab-on-a-chip microsystem, integration with the microfluidics has been achieved by using a novel fabrication method of 3-D embedded microchannels using the polymer SU-8 as structural material. The optofluidic chip shows good performances for biosensing

Analysis of Farmland Abandonment and the Extent and Location of Agricultural Areas that are Actually Abandoned or are in Risk to be Abandoned

Farmland abandonment (FLA) can be defined as the cessation of agricultural activities on a given surface of land and not taken by another activity (such as urbanisation or afforestation). This process attracts the attention of policy-makers both at national and EU level, in particular within the context of the Rural Development Policy. And, considering its importance in environmental and socio-economic terms, it is necessary to better understand the geographic distribution and strength of farmland abandonment trends in the EU-27, and to develop indicators to identify the most important farmland abandonment tendencies. The first aim of this study was to establish the state of the art concerning farmland abandonment (definition, type) and methodologies for identifying/quantifying this phenomenon (dataset, period of analysis, scale). Then, it was about contributing to a new definition of Less Favoured Areas by assessing the driving forces of farmland abandonment and preparing the guidelines for agri-environmental indicator Nr 14 [COM2006 (508final)] by evaluating the state and risk of farmland abandonment. The proposed methodology was based on two main elements: the variation of the UAA and the definition of rural areas. After identifying clear definitions for each variable, the way to consider the main flows of land use changes was studied. Due to a lack of accurate data at the appropriate scale, farmland afforestation could not be separated from the flow of FLA and the flow from farmland to sealed soil was estimated based on the hypothesis that it was mainly located in urban areas where the population density is high or increases very fast. The methodology was tested in three of the main agricultural countries in the EU-27 in terms of surface (France, Spain and Poland). Then, five regions were chosen to cover different contexts where a high level of FLA was observed and interviews of experts and stakeholders completed the study. Based on the results on the main causes of FLA, indicators of risk were proposed and recommendations were formulated to improve the methodology and datasets.JRC.H.5-Rural, water and ecosystem resource

X-ray topographic determination of the granular structure in a graphite mosaic crystal: a three-dimensional reconstruction

Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite (HOPG) crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. This is performed with a direct reconstruction from the intensity distribution on such topographs. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains. This data analysis leads to a new method for the characterization of mosaic crystals. Perspectives and limits of applicability of this method are discussed

X-ray topographic determination of the granular structure in a graphite mosaic crystal : a three-dimensional reconstruction

Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite (HOPG) crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. This is performed with a direct reconstruction from the intensity distribution on such topographs. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains. This data analysis leads to a new method for the characterization of mosaic crystals. Perspectives and limits of applicability of this method are discussed

Precision determination of the dpi -> NN transition strength at threshold

An unusual but effective way to determine at threshold the dpi -> NN transition strength is to exploit the hadronic ground-state broadening in pionic deuterium, accessible by x-ray spectroscopy. The broadening is dominated by the true absorption channel dpi- -> nn, which is related to s-wave pion production pp -> dpi+ by charge symmetry and detailed balance. Using the exotic atom circumvents the problem of Coulomb corrections to the cross section as necessary in the production experiments. Our dedicated measurement finds (1171+23/-49) meV for the broadening yielding (252+5/-11) \mub.Comment: 4 pages, 2 figures, 1 tabl

PrevenBox: Evaluation of concomitant use of preventive medications with OnabotulinumtoxinA in migraine

P114 Background: OnabotulinumtoxinA is an effective, tolerable and safepreventive treatment for chronic migraine (CM). Other than a reduc-tion in headache frequency or disability, in CM the withdrawal ofconcomitant preventive medication indicates treatment effectivenessand quality of life improvement. Objective: To characterize the change in the use of oral preventivemedication after treatment with OnabotulinumtoxinA in patientswith migraine. Methods: This is a multicentre study. We consecutively included pa-tients with migraine (ICHD-3) that were on preventive treatment withOnabotulinumtoxinA. We retrospectively collected demographic data, diagnosis of migraine, frequency and intensity changes, number ofcycle and OnabotulinumtoxinA dose. In addition, we listed the initialand current preventive treatment (number of drugs and group) andthe number and cycle of medications withdrawn. We performed aunivariate and logistic regression analysis. Results: We included 542 patients: 87.6% women, mean age 47.6 ±11.7 years. A 89.3% had chronic migraine and 10.8% had high fre-quency episodic migraine. The mean reduction in frequency aftertreatment was 13.4±8.2 headache days/month. At baseline, a 91.3%took other preventives and during treatment with Onabotulinumtox-inA a 58.6% withdrew at least one drug, 25.8% stopped completelyall oral preventive drugs. Factors associated with withdrawal were:being male, having >50% response in frequency and intensity, thenumber of infiltrations and a shorter chronification period until thefirst OnabotulinumtoxinA administration (p <0.05). The multivariateanalysis showed that a better response in intensity (OR:1.8 [1.4-2.2], p<0.001), a greater number of infiltrations (OR:1.1 [1.0-1.2], p<0.001)and a shorter chronification period (OR:0.994 [0.992-0.997], p<0.001)were predictors of withdrawal. The ROC curve, showed that 6 Onabo-tulinumtoxinA cycles was the cut-off point that better predicted oralpreventive medication withdrawal (p <0.001). Conclusions: Treatment with OnabotulinumtoxinA reduces the use ofother preventive medications for migraine. The highest probability ofwithdrawal occurs after 6 cycles of treatment