108 research outputs found
The Effect of Closing Date and Type of Utilisation in Autumn on Grass Yield in Spring
Due to the low cost of grazed grass, most dairy farmers extend the grazing period in autumn. However, delaying the closing date may reduce the grass yield in the following spring (Roche et al., 1996; O’Donovan et al., 2002). The objective of this experiment, conducted in the Swiss lowlands, was to quantify the effects of closing date and type of utilisation in autumn on grass yield in the following spring
Influence of Grazing Exclusion on Vegetation and Productivity of Kyrgyz Pastures
The aim of this study was to assess the effect of grazing exclusion on the vegetation and productivity of: (1) pastures near villages that are grazed intensively through-out the year; and (2) pastures, which are used in summer and are less intensively grazed through the remainder of the year. The potential of degraded pastures to recover, when protected from overgrazing, was also evaluated. Six pastures (3 located in or near villages and 3 used for summer grazing) were selected with local community representatives in 3 pilot regions of Kyrgyzstan (the Lahol and Теrеk regions of Naryn oblast and the Оrgochor region of Issyk-Kul oblast). This paper presents some preliminary results after 4 years of grazing exclusion from the Orgochor pilot region
In Situ Reduction and Oxidation of Nickel from Solid Oxide Fuel Cells in a Titan ETEM
Environmental transmission electron microscopy was used to characterize in situ the reduction and oxidation of nickel from a Ni/YSZ solid oxide fuel cell anode support between 300-500°C. The reduction is done under low hydrogen pressure. The reduction initiates at the NiO/YSZ interface, then moves to the center of the NiO grain. At higher temperature the reduction occurs also at the free NiO surface and the NiO/NiO grain boundaries. The growth of Ni is epitaxial on its oxide. Due to high volume decrease, nanopores are formed during reduction. During oxidation, oxide nanocrystallites are formed on the nickel surface. The crystallites fill up the nickel porosity and create an inhomogeneous structure with remaining voids. This change in structure causes the nickel oxide to expand during a RedOx cycle
Reduction of nickel oxide particles by hydrogen studied in an environmental TEM
In situ reduction of nickel oxide (NiO) particles is performed under 1.3 mbar of hydrogen gas (H-2) in an environmental transmission electron microscope (ETEM). Images, diffraction patterns and electron energy-loss spectra (EELS) are acquired to monitor the structural and chemical evolution of the system during reduction, whilst increasing the temperature. Ni nucleation on NiO is either observed to be epitaxial or to involve the formation of randomly oriented grains. The growth of Ni crystallites and the movement of interfaces result in the formation of pores within the NiO grains to accommodate the volume shrinkage associated with the reduction. Densification is then observed when the sample is nearly fully reduced. The reaction kinetics is obtained using EELS by monitoring changes in the shapes of the Ni L-2,L-3 white lines. The activation energy for NiO reduction is calculated from the EELS data using both a physical model-fitting technique and a model-independent method. The results of the model-fitting procedure suggest that the reaction is described by Avrami models (whereby the growth and impingement of Ni domains control the reaction), in agreement with the ETEM observations
Determinants of parents' reticence toward vaccination in urban areas in Benin (West Africa)
Analysis of the data reveals those who are vaccination-reticent say it goes against the will of God, that it is a poison from the “white witch doctor,” and a sin. Members of the control group argued against this, but without conviction. They adhere to the principle of obedience to authority, a biblical precept invoked when the vaccinators oblige them to vaccinate their children. To limit the spread of this phenomenon among the religious population of the cities like Parakou and Cotonou in Benin, more detailed information and negotiation between health authorities and pastors of the churches are essential
Vapor phase deposition of perovskite photovoltaics:Short track to commercialization?
While perovskite-based photovoltaics (PV) is progressing toward commercialization, it remains an open question which fabrication technology - solution-based, vapor-based, or combinations - will pave the way to faster economic breakthrough. The vast majority of research studies make use of solution-processed perovskite thin films, which benefit from a rapid optimization feedback and inexpensive to procure tools in modern research laboratories, but vapor phase deposition processes dominate today's established thin-film manufacturing. As research and development of vapor phase processed perovskite thin films are still strongly underrepresented in literature, their full potential is yet to be identified. In this collaborative perspective of academic influenced by industrial views, we convey a balanced viewpoint on the prospects of vapor-based processing of perovskite PV at an industrial scale. Our perspective highlights the conceptual advantages of vapor phase deposition, discusses the most crucial process parameters in a technology assessment, contains an overview about relevant global industry clusters, and provides an outlook on the commercialization perspectives of the perovskite technology in general.</p
Developing stakeholder-driven scenarios on land sharing and land sparing – Insights from five European case studies
Empirical research on land sharing and land sparing has been criticized because preferences of local stakeholders, socio-economic aspects, a bundle of ecosystem services and the local context were only rarely integrated. Using storylines and scenarios is a common approach to include land use drivers and local contexts or to cope with the uncertainties of future developments. The objective of the presented research is to develop comparable participatory regional land use scenarios for the year 2030 reflecting land sharing, land sparing and more intermediate developments across five different European landscapes (Austria, Germany, Switzerland, The Netherlands and Spain). In order to ensure methodological consistency among the five case studies, a hierarchical multi-scale scenario approach was developed, which consisted of i) the selection of a common global storyline to frame a common sphere of uncertainty for all case studies, ii) the definition of three contrasting qualitative European storylines (representing developments for land sharing, land sparing and a balanced storyline), and iii) the development of three explorative case study-specific land use scenarios with regional stakeholders in workshops. Land use transition rules defined by stakeholders were used to generate three different spatially-explicit scenarios for each case study by means of high-resolution land use maps. All scenarios incorporated various aspects of land use and management to allow subsequent quantification of multiple ecosystem services and biodiversity indicators. The comparison of the final scenarios showed both common as well as diverging trends among the case studies. For instance, stakeholders identified further possibilities to intensify land management in all case studies in the land sparing scenario. In addition, in most case studies stakeholders agreed on the most preferred scenario, i.e. either land sharing or balanced, and the most likely one, i.e. balanced. However, they expressed some skepticism regarding the general plausibility of land sparing in a European context. It can be concluded that stakeholder perceptions and the local context can be integrated in land sharing and land sparing contexts subject to particular process design principles
Obesity trends and body mass index changes after starting antiretroviral treatment : the Swiss HIV Cohort Study
BACKGROUND: The factors that contribute to increasing obesity rates in human immunodeficiency virus (HIV)-positive persons and to body mass index (BMI) increase that typically occurs after starting antiretroviral therapy (ART) are incompletely characterized.
METHODS: We describe BMI trends in the entire Swiss HIV Cohort Study (SHCS) population and investigate the effects of demographics, HIV-related factors, and ART on BMI change in participants with data available before and 4 years after first starting ART.
RESULTS: In the SHCS, overweight/obesity prevalence increased from 13% in 1990 (n = 1641) to 38% in 2012 (n = 8150). In the participants starting ART (n = 1601), mean BMI increase was 0.92 kg/m(2) per year (95% confidence interval, .83-1.0) during year 0-1 and 0.31 kg/m(2) per year (0.29-0.34) during years 1-4. In multivariable analyses, annualized BMI change during year 0-1 was associated with older age (0.15 [0.06-0.24] kg/m(2)) and CD4 nadir <199 cells/µL compared to nadir >350 (P < .001). Annualized BMI change during years 1-4 was associated with CD4 nadir <100 cells/µL compared to nadir >350 (P = .001) and black compared to white ethnicity (0.28 [0.16-0.37] kg/m(2)). Individual ART combinations differed little in their contribution to BMI change.
CONCLUSIONS: Increasing obesity rates in the SHCS over time occurred at the same time as aging of the SHCS population, demographic changes, earlier ART start, and increasingly widespread ART coverage. Body mass index increase after ART start was typically biphasic, the BMI increase in year 0-1 being as large as the increase in years 1-4 combined. The effect of ART regimen on BMI change was limited
Higher Risk of Incident Hepatitis C Virus Coinfection Among Men Who Have Sex With Men, in Whom the HIV Genetic Bottleneck at Transmission Was Wide
Background. High-risk sexual behaviors have been suggested as drivers of the recent dramatic increase of sexually transmitted hepatitis C virus (HCV) among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM). Methods. We assessed the association between the genetic bottleneck of HIV at transmission and the prevalence and incidence of HCV coinfection in HIV-infected MSM from the Swiss HIV Cohort Study (SHCS). As a proxy for the width of the transmission bottleneck, we used the fraction of ambiguous nucleotides detected by genotypic resistance tests sampled during early HIV infection. We defined a broad bottleneck as a fraction of ambiguous nucleotides exceeding a previously established threshold (0.5%). Results. From the SHCS, we identified 671 MSM with available results of HCV serologic tests and with an HIV genotypic resistance test performed during early HIV infection. Of those, 161 (24.0%) exhibited a broad HIV transmission bottleneck, 38 (5.7%) had at least 1 positive HCV test result, and 26 (3.9%) had an incident HCV infection. Individuals with broad HIV transmission bottlenecks exhibited a 2-fold higher odds of having ever experienced an HCV coinfection (odds ratio, 2.2 [95% confidence interval {CI}, 1.1-4.3]) and a 3-fold higher hazard of having an incident HCV infection (hazard ratio, 3.0 [95% CI, 1.4-6.6]) than individuals with narrow HIV transmission bottlenecks. Conclusions. Our results indicate that the currently occurring sexual spread of HCV is focused on MSM who are prone to exhibit broad HIV transmission bottlenecks. This is consistent with an important role of high-risk behavior and mucosal barrier impairment in the transmission of HCV among MS
Increases in condomless sex in the Swiss HIV Cohort Study.
Condomless sex is a key driver of sexually transmitted diseases. In this study, we assess the long-term changes (2000-2013) of the occurrence of condomless sex among human immunodeficiency virus (HIV)-infected individuals enrolled in the Swiss HIV Cohort study. The frequencies with which HIV-infected individuals reported condomless sex were either stable or only weakly increasing for 2000-2008. For 2008-2013, these rates increased significantly for stable relationships among heterosexuals and men who have sex with men (MSM) and for occasional relationships among MSM. Our results highlight the increasing public health challenge posed by condomless sex and show that condomless sex has been increasing even in the most recent years
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