440 research outputs found
Positive Interspecific Relationship between Temporal Occurrence and Abundance in Insects
One of the most studied macroecological patterns is the interspecific abundance–occupancy relationship, which relates species distribution and abundance across space. Interspecific relationships between temporal distribution and abundance, however, remain largely unexplored. Using data for a natural assemblage of tabanid flies measured daily during spring and summer in Nova Scotia, we found that temporal occurrence (proportion of sampling dates in which a species occurred in an experimental trap) was positively related to temporal mean abundance (number of individuals collected for a species during the study period divided by the total number of sampling dates). Moreover, two models that often describe spatial abundance–occupancy relationships well, the He–Gaston and negative binomial models, explained a high amount of the variation in our temporal data. As for the spatial abundance–occupancy relationship, the (temporal) aggregation parameter, k, emerged as an important component of the hereby named interspecific temporal abundance–occurrence relationship. This may be another case in which a macroecological pattern shows similarities across space and time, and it deserves further research because it may improve our ability to forecast colonization dynamics and biological impacts
Second surgery for progressive glioblastoma: a multi‐centre questionnaire and cohort‐based review of clinical decision‐making and patient outcomes in current practice
PURPOSE: Glioblastoma prognosis is poor. Treatment options are limited at progression. Surgery may benefit, but no quality guidelines exist to inform patient selection. We sought to describe variations in surgical management at progression, highlight where further evidence is needed, and build towards a consensus strategy. METHODS: Current practice in selection of patients with progressive GBM for second surgery was surveyed online amongst specialists in the UK and Europe. We complemented this with an assessment of practice in a retrospective cohort study from six United Kingdom neurosurgical units. We used descriptive statistics to analyse the data. RESULTS: 234 questionnaire responses were received. Maintaining or improving patient quality of life was key to decision making, with variation as to whether patient age, performance status or intended extent of resection was relevant. MGMT methylation status was not important. Half considered no minimum time after first surgery. 288 patients were reported in the cohort analysis. Median time to second surgery from first surgery 390 days. Median overall survival 815 days, with no association between time to second surgery and time to death (p = 0.874). CONCLUSIONS: This is the most wide-ranging examination of contemporaneous practice in management of GBM progression. Without evidence-based guidelines, the variation is unsurprising. We propose consensus guidelines for consideration, to reduce heterogeneity in decision making, support data collection and analysis of factors influencing outcomes, and to inform clinical trials to establish whether second surgery improves patient outcomes, or simply selects to patients already performing well
Personalised cancer follow-up: risk stratification, needs assessment or both?
First paragraph: There are approximately 2 million people now living with or beyond cancer in the UK (Maddams et al, 2009) and this number is increasing. Cancer survivors can experience physical, psychological and social consequences as a result of the disease and the treatments received (Jefford et al, 2008; Foster et al, 2009). The effects may be immediate, some of which will resolve and others may persist and become long-term. Late effects can also occur and the interval between the end of treatment and onset can range from a few weeks (e.g. lymphoedema after axillary node removal) to several years (e.g. heart disease following radiotherapy to the chest area). Problems will be individual to each patient due to a unique combination of circumstances including the site and stage of the cancer, the type of treatment(s) given, the age of the patient, genetic factors, concomitant co-morbidities, family and social circumstances, and personality traits
Protocol for a pilot randomised controlled clinical trial to compare the effectiveness of a graduated three layer straight tubular bandaging system when compared to a standard short stretch compression bandaging system in the management of people with venous ulceration: 3VSS2008
<p>Abstract</p> <p>Background</p> <p>The incidence of venous ulceration is rising with the increasing age of the general population. Venous ulceration represents the most prevalent form of difficult to heal wounds and these problematic wounds require a significant amount of health care resources for treatment. Based on current knowledge multi-layer high compression system is described as the gold standard for treating venous ulcers. However, to date, despite our advances in venous ulcer therapy, no convincing low cost compression therapy studies have been conducted and there are no clear differences in the effectiveness of different types of high compression.</p> <p>Methods/Design</p> <p>The trial is designed as a pilot multicentre open label parallel group randomised trial. Male and female participants aged greater than 18 years with a venous ulcer confirmed by clinical assessment will be randomised to either the intervention compression bandage which consists of graduated lengths of 3 layers of elastic tubular compression bandage or to the short stretch inelastic compression bandage (control). The primary objective is to assess the percentage wound reduction from baseline compared to week 12 following randomisation. Randomisation will be allocated via a web based central independent randomisation service (nQuery v7) and stratified by study centre and wound size ≤ 10 cm<sup>2 </sup>or >10 cm<sup>2</sup>. Neither participants nor study staff will be blinded to treatment. Outcome assessments will be undertaken by an assessor who is blinded to the randomisation process.</p> <p>Discussion</p> <p>The aim of this study is to evaluate the efficacy and safety of two compression bandages; graduated three layer straight tubular bandaging (3L) when compared to standard short stretch (SS) compression bandaging in healing venous ulcers in patients with chronic venous ulceration. The trial investigates the differences in clinical outcomes of two currently accepted ways of treating people with venous ulcers. This study will help answer the question whether the 3L compression system or the SS compression system is associated with better outcomes.</p> <p>Trial Registration</p> <p>ACTRN12608000599370</p
The Effort of Increasing Reynolds Number in Projection-Based Reduced Order Methods: From Laminar to Turbulent Flows
We present in this double contribution two different reduced order strategies for incompressible parameterized Navier-Stokes equations characterized by varying Reynolds numbers. The first strategy deals with low Reynolds number (laminar flow) and is based on a stabilized finite element method during the offline stage followed by a Galerkin projection on reduced basis spaces generated by a greedy algorithm. The second methodology is based on a full order finite volume discretization. The latter methodology will be used for flows with moderate to high Reynolds number characterized by turbulent patterns. For the treatment of the mentioned turbulent flows at the reduced order level, a new POD-Galerkin approach is proposed. The new approach takes into consideration the contribution of the eddy viscosity also during the online stage and is based on the use of interpolation. The two methodologies are tested on classic benchmark test cases
HIV Prevalence, Risks for HIV Infection, and Human Rights among Men Who Have Sex with Men (MSM) in Malawi, Namibia, and Botswana
BACKGROUND: In the generalized epidemics of HIV in southern Sub-Saharan Africa, men who have sex with men have been largely excluded from HIV surveillance and research. Epidemiologic data for MSM in southern Africa are among the sparsest globally, and HIV risk among these men has yet to be characterized in the majority of countries. METHODOLOGY: A cross-sectional anonymous probe of 537 men recruited with non-probability sampling among men who reported ever having had sex with another man in Malawi, Namibia, and Botswana using a structured survey instrument and HIV screening with the OraQuick(c) rapid test kit. PRINCIPAL FINDINGS: The HIV prevalence among those between the ages of 18 and 23 was 8.3% (20/241); 20.0% (42/210) among those 24-29; and 35.7% (30/84) among those older than 30 for an overall prevalence of 17.4% (95% CI 14.4-20.8). In multivariate logistic regressions, being older than 25 (aOR 4.0, 95% CI 2.0-8.0), and not always wearing condoms during sex (aOR 2.6, 95% CI 1.3-4.9) were significantly associated with being HIV-positive. Sexual concurrency was common with 16.6% having ongoing concurrent stable relationships with a man and a woman and 53.7% had both male and female sexual partners in proceeding 6 months. Unprotected anal intercourse was common and the use of petroleum-based lubricants was also common when using condoms. Human rights abuses, including blackmail and denial of housing and health care was prevalent with 42.1% (222/527) reporting at least one abuse. CONCLUSIONS: MSM are a high-risk group for HIV infection and human rights abuses in Malawi, Namibia, and Botswana. Concurrency of sexual partnerships with partners of both genders may play important roles in HIV spread in these populations. Further epidemiologic and evaluative research is needed to assess the contribution of MSM to southern Africa's HIV epidemics and how best to mitigate this. These countries should initiate and adequately fund evidence-based and targeted HIV prevention programs for MSM
The prognostic influence of bcl-2 in malignant glioma
The bcl-2 gene is one of a complex group of genes which control programmed cell death. Bcl-2 acts to extend cell survival by blocking apoptosis, and thereby may influence tumour prognosis. This study of 187 high grade gliomas reviews clinicopathological prognostic features and the relationship to bcl-2 expression. Bcl-2 immunostaining was assessed in 159 specimens from these patients, by scoring systems of 0 to 3 for intensity of scoring and proportion of cells staining. Age, histology, pre- and post-operative performance status were found to be strongly predictive of survival (log rank test P<0.0001). The type of surgery performed did not influence survival in this group of patients. The expression of bcl-2 had a significant relationship with survival (univariate Cox model P=0.0302, hazard ratio 0.8, 95% confidence interval 0.65–0.98), with increased staining associated with improved survival. Multivariate analysis showed performance status, histology and proportion of cells staining for bcl-2 to be independently predictive of survival. Bcl-2 staining was not related to histological grade of tumours
Magnetisation switching of FePt nanoparticle recording medium by femtosecond laser pulses
Manipulation of magnetisation with ultrashort laser pulses is promising for information storage device applications. The dynamics of the magnetisation response depends on the energy transfer from the photons to the spins during the initial laser excitation. A material of special interest for magnetic storage are FePt nanoparticles, for which switching of the magnetisation with optical angular momentum was demonstrated recently. The mechanism remained unclear. Here we investigate experimentally and theoretically the all-optical switching of FePt nanoparticles. We show that the magnetisation switching is a stochastic process. We develop a complete multiscale model which allows us to optimize the number of laser shots needed to switch the magnetisation of high anisotropy FePt nanoparticles in our experiments. We conclude that only angular momentum induced optically by the inverse Faraday effect will provide switching with one single femtosecond laser pulse.EC under Contract No. 281043, FemtoSpin. The work at Greifswald University
was supported by the German research foundation (DFG), projects MU MU 1780/8-1, MU 1780/10-1. Research
at Göttingen University was supported via SFB 1073, Projects A2 and B1. Research at Uppsala University was
supported by the Swedish Research Council (VR), the Röntgen-Ångström Cluster, the Knut and Alice Wallenberg
Foundation (Contract No. 2015.0060), and Swedish National Infrastructure for Computing (SNIC). Research at
Kiel University was supported by the DFG, projects MC 9/9-2, MC 9/10-2. P.N. acknowledges support from EU
Horizon 2020 Framework Programme for Research and Innovation (2014-2020) under Grant Agreement No.
686056, NOVAMAG. The work in Konstanz was supported via the Center for Applied Photonics
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