471 research outputs found

    Sustainability and management of groundwater resources in the Minchin Basin, Gansu Province

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    This project is concerned with a study of the sustainability of irrigation agriculture in the Minqin Basin in Gansu Province, China. In this region agriculture is dependent on water supply from groundwater resources. However, recharge rates from precipitation are very low and surface flow from the Tibetan Plateau is intercepted upstream to provide water for the city ofWuwei and its region. Future climate change may further decrease supply. Already many shallow wells have been exhausted or abandoned because of salinity problems, and new wells are now being drilled to pump water from depths up to 300m

    In vitro comparison of four treatments which discourage infestation by head lice

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    Products which discourage the transmission of head lice are appealing; however, few studies have tested this concept. This study aims to test the efficacy of four commercial products which claim to discourage infestation by head lice; MOOV Head Lice Defence Spray (MOOV), Wild Child Quit Nits Head Lice Defence Spray (Wild Child), 100% Natural Head Lice Beater (Lice Beater) or Lysout Natural Anti-Lice Spray (Lysout). An in vitro challenge test was used. Briefly, one half of a filter paper lining the base of a petri dish was treated with the test product. Lice were then introduced to the centre of the dish, which was covered and placed in the dark at 20°C for 30 min. The number of lice on the treated and untreated sides of the filter paper was then counted after 2, 4 and 8 h post-application. MOOV was significantly more effective at discouraging the transmission of lice than the water control (p < 0.01), while Wild Child and Lysout were not at all time points. Lice Beater was significantly worse than the water control after 2 h (p < 0.01), while there was no difference after 4 and 8 h. MOOV was found to perform significantly better than Wild Child (p < 0.05) and Lice Beater (p < 0.05) at all time points. It also performed significantly better than Lysout at 2 (p < 0.05) and 8 h (p < 0.05), but not 4 h. MOOV offers the best efficacy and consistency of performance of the four products tested to discourage the transmission of head lice

    On the Perturbative Stability of Quantum Field Theories in de Sitter Space

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    We use a field theoretic generalization of the Wigner-Weisskopf method to study the stability of the Bunch-Davies vacuum state for a massless, conformally coupled interacting test field in de Sitter space. We find that in λϕ4\lambda \phi^4 theory the vacuum does {\em not} decay, while in non-conformally invariant models, the vacuum decays as a consequence of a vacuum wave function renormalization that depends \emph{singularly} on (conformal) time and is proportional to the spatial volume. In a particular regularization scheme the vacuum wave function renormalization is the same as in Minkowski spacetime, but in terms of the \emph{physical volume}, which leads to an interpretation of the decay. A simple example of the impact of vacuum decay upon a non-gaussian correlation is discussed. Single particle excitations also decay into two particle states, leading to particle production that hastens the exiting of modes from the de Sitter horizon resulting in the production of \emph{entangled superhorizon pairs} with a population consistent with unitary evolution. We find a non-perturbative, self-consistent "screening" mechanism that shuts off vacuum decay asymptotically, leading to a stationary vacuum state in a manner not unlike the approach to a fixed point in the space of states.Comment: 36 pages, 4 figures. Version to appear in JHEP, more explanation

    Prospects and challenges of environmental DNA (eDNA) monitoring in freshwater ponds

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    Environmental DNA (eDNA) analysis is a rapid, non-invasive, cost-efficient biodiversity monitoring tool with enormous potential to inform aquatic conservation and management. Development is ongoing, with strong commercial interest, and new uses are continually being discovered. General applications of eDNA and guidelines for best practice in freshwater systems have been established, but habitat-specific assessments are lacking. Ponds are highly diverse, yet understudied systems that could benefit from eDNA monitoring. However, eDNA applications in ponds and methodological constraints specific to these environments remain unaddressed. Following a stakeholder workshop in 2017, researchers combined knowledge and expertise to review these applications and challenges that must be addressed for the future and consistency of eDNA monitoring in ponds. The greatest challenges for pond eDNA surveys are representative sampling, eDNA capture, and potential PCR inhibition. We provide recommendations for sampling, eDNA capture, inhibition testing, and laboratory practice, which should aid new and ongoing eDNA projects in ponds. If implemented, these recommendations will contribute towards an eventual broad standardisation of eDNA research and practice, with room to tailor workflows for optimal analysis and different applications. Such standardisation will provide more robust, comparable, and ecologically meaningful data to enable effective conservation and management of pond biodiversity

    Optimizing Nervous System-Specific Gene Targeting with Cre Driver Lines: Prevalence of Germline Recombination and Influencing Factors.

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    The Cre-loxP system is invaluable for spatial and temporal control of gene knockout, knockin, and reporter expression in the mouse nervous system. However, we report varying probabilities of unexpected germline recombination in distinct Cre driver lines designed for nervous system-specific recombination. Selective maternal or paternal germline recombination is showcased with sample Cre lines. Collated data reveal germline recombination in over half of 64 commonly used Cre driver lines, in most cases with a parental sex bias related to Cre expression in sperm or oocytes. Slight differences among Cre driver lines utilizing common transcriptional control elements affect germline recombination rates. Specific target loci demonstrated differential recombination; thus, reporters are not reliable proxies for another locus of interest. Similar principles apply to other recombinase systems and other genetically targeted organisms. We hereby draw attention to the prevalence of germline recombination and provide guidelines to inform future research for the neuroscience and broader molecular genetics communities

    Methods for specifying the target difference in a randomised controlled trial : the Difference ELicitation in TriAls (DELTA) systematic review

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    Peer reviewedPublisher PD

    Granulocyte-colony stimulating factor for stroke treatment: mechanisms of action and efficacy in preclinical studies

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    G-CSF is widely employed for the treatment of chemotherapy-induced neutropenia. Recently, neuroprotective effects of G-CSF in animal stroke models were discovered including infarct size reduction and enhancement of functional recovery. The underlying mechanisms of action of G-CSF in ischemia appear to be a direct anti-apoptotic activity in neurons and a neurogenesis inducing capacity. Additional effects may be based on the stimulation of new blood-vessel formation, the stimulation of immunocompetence and -modulation as well as on bone marrow mobilization. In addition to a discussion of these mechanisms, we will review the available preclinical studies and analyze their impact on the overall efficacy of G-CSF in experimental stroke

    Familial hypercholesterolemia and elevated lipoprotein(a) : double heritable risk and new therapeutic opportunities

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    Vuorio A, Watts GF, Schneider WJ, Tsimikas S, Kovanen PT (Mehilainen Airport Health Centre, Vantaa; University of Helsinki, Helsinki, Finland; University of Western Australia, Perth, Australia; Royal Perth Hospital, Perth, Australia; Medical University of Vienna, Vienna, Austria; University of California San Diego, La Jolla, CA, USA; Wihuri Research Institute, Helsinki, Finland). Familial hypercholesterolemia and elevated lipoprotein(a): double heritable risk and new therapeutic opportunities (Review). J Intern Med 2020; 287: 2-18. There is compelling evidence that the elevated plasma lipoprotein(a) [Lp(a)] levels increase the risk of atherosclerotic cardiovascular disease (ASCVD) in the general population. Like low-density lipoprotein (LDL) particles, Lp(a) particles contain cholesterol and promote atherosclerosis. In addition, Lp(a) particles contain strongly proinflammatory oxidized phospholipids and a unique apoprotein, apo(a), which promotes the growth of an arterial thrombus. At least one in 250 individuals worldwide suffer from the heterozygous form of familial hypercholesterolemia (HeFH), a condition in which LDL-cholesterol (LDL-C) is significantly elevated since birth. FH-causing mutations in the LDL receptor gene demonstrate a clear gene-dosage effect on Lp(a) plasma concentrations and elevated Lp(a) levels are present in 30-50% of patients with HeFH. The cumulative burden of two genetically determined pro-atherogenic lipoproteins, LDL and Lp(a), is a potent driver of ASCVD in HeFH patients. Statins are the cornerstone of treatment of HeFH, but they do not lower the plasma concentrations of Lp(a). Emerging therapies effectively lower Lp(a) by as much as 90% using RNA-based approaches that target the transcriptional product of the LPA gene. We are now approaching the dawn of an era, in which permanent and significant lowering of the high cholesterol burden of HeFH patients can be achieved. If outcome trials of novel Lp(a)-lowering therapies prove to be safe and cost-effective, they will provide additional risk reduction needed to effectively treat HeFH and potentially lower the CVD risk in these high-risk patients even more than currently achieved with LDL-C lowering alone.Peer reviewe

    Behavioral and cognitive interventions to improve treatment adherence and access to HIV care among older adults in sub-Saharan Africa: an updated systematic review

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    BACKGROUND: Approximately 14% of Africans infected with HIV are over the age of 50, yet few intervention studies focus on improving access to care, retention in care, and adherence to antiretroviral therapy (ART) in this population. A review of the published literature until 2012, found no relevant ART management and care interventions for older people living with HIV (OPLHIV) in sub-Saharan Africa. The aim of this systematic review is to update the original systematic review of intervention studies on OPLHIV, with a focus on evidence from sub-Saharan Africa. METHODS: We conducted a systematic review of the available published literature from 2012 to 2017 to explore behavioral and cognitive interventions addressing access to ART, retention in HIV care and adherence to ART in sub-Saharan Africa that include older adults (50+). We searched three databases (MEDLINE, EMBASE, and Education Resources Information Center) using relevant Medical Subject Headings (MeSH) terms as well as a manual search of the reference lists. No language restrictions were placed. We identified eight articles which were analyzed using content analysis with additional information obtained directly from the corresponding authors. RESULTS AND DISCUSSION: There were no studies that exclusively focused on OPLHIV. Three studies referred only to participants being over 18 years and did not specify age categories. Therefore, it is unclear whether these studies actively considered people living with HIV over the age of 50. Although the studies sampled older adults, they lacked sufficient data to draw conclusions about the relevance of the outcomes of this group. CONCLUSIONS: These findings underscore the need to increase the evidence-base of which interventions will work for older Africans on ART
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