698 research outputs found
Modelling shoreline evolution in the vicinity of a groyne and a river
Analytical solutions to the equations governing shoreline evolution are well-known and have value both as pedagogical tools and for conceptual design. Nevertheless, solutions have been restricted to a fairly narrow class of conditions with limited applicability to real-life situations. We present a new analytical solution for a widely encountered situation where a groyne is constructed close to a river to control sediment movement. The solution, which employs Laplace transforms, has the advantage that a solution for time-varying conditions may be constructed from the solution for constant conditions by means of the Heaviside procedure. Solutions are presented for various combinations of wave conditions and sediment supply/removal by the river. An innovation introduced in this work is the capability to provide an analytical assessment of the accretion or erosion caused near the groyne due to its proximity to the river which may act either as a source or a sink of sediment material
Massive Field-Theory Approach to Surface Critical Behavior in Three-Dimensional Systems
The massive field-theory approach for studying critical behavior in fixed
space dimensions is extended to systems with surfaces.This enables one to
study surface critical behavior directly in dimensions without having to
resort to the expansion. The approach is elaborated for the
representative case of the semi-infinite |\bbox{\phi}|^4 -vector model
with a boundary term {1/2} c_0\int_{\partial V}\bbox{\phi}^2 in the action.
To make the theory uv finite in bulk dimensions , a renormalization
of the surface enhancement is required in addition to the standard mass
renormalization. Adequate normalization conditions for the renormalized theory
are given. This theory involves two mass parameter: the usual bulk `mass'
(inverse correlation length) , and the renormalized surface enhancement .
Thus the surface renormalization factors depend on the renormalized coupling
constant and the ratio . The special and ordinary surface transitions
correspond to the limits with and ,
respectively. It is shown that the surface-enhancement renormalization turns
into an additive renormalization in the limit . The
renormalization factors and exponent functions with and
that are needed to determine the surface critical exponents of the special and
ordinary transitions are calculated to two-loop order. The associated series
expansions are analyzed by Pad\'e-Borel summation techniques. The resulting
numerical estimates for the surface critical exponents are in good agreement
with recent Monte Carlo simulations. This also holds for the surface crossover
exponent .Comment: Revtex, 40 pages, 3 figures, and 8 pictograms (included in equations
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Microwave Heating Demonstrator (MHD) payload – for fabricating construction components and extracting resources
Lunar regolith could be thermally treated to extract resources and build an outer habitat shell using additive manufacturing techniques (a.k.a. 3D printing) by robots [1]. Proof of concept experiments has demonstrated that microwaves couple efficiently with lunar regolith and sinter/melt it to build 3D structures and enable resource extraction [2]. However, there are still several questions that can only be answered through experiments on the Moon surface. Thus, the Open University (OU) initiated a collaborative project MARVEL (Microwave heating Apparatus for Regolith Variant Experiments for Lunar ISRU), with Added Value Solutions UK Ltd. and VIPER RF. The team aims to prepare the groundwork for the UK to lead the development of a Microwave Heating Demonstrator (MHD) payload on future missions to the Moon with the flight hardware being developed and built in the UK. The initial concept development of the MHD payload was completed with support from UKSA’s NSTP GEI funding (Figure 1 [3]).
In this presentation, we will report the current progress of the MHD development conducted through the NSTP Pathfinder grant, focusing on the challenges with cavity design and the concept of a 1 kW solid-state microwave generator that could be used for future lunar missions
Prevention of Vitamin D deficiency in infancy: daily 400 IU vitamin D is sufficient
<p>Summary</p> <p>Aim-objective</p> <p>Vitamin D deficiency and rickets in developing countries continues to be a major health problem. Additionally, the increase of cases of rickets in children of some ethnic groups in the United States and European countries has provided this issue to be updated. Obviously, powerful strategies are necessary to prevent vitamin D deficiency nation-wide. In 2005, a nationwide prevention program for vitamin D deficiency was initiated, recommending 400 IU vitamin D per a day.</p> <p>This study was designed to evaluate the efficacy of the prevention program.</p> <p>Methods</p> <p>Eighty-five infants who were recalled as part of the national screening program for congenital hypothyroidism between February 2010 and August 2010 at Kocaeli University Children's Hospital were evaluated in terms of their vitamin D status as well. All babies had been provided with free vitamin D (Cholecalciferol) solution and recommended to receive 400 IU (3 drops) daily. Information regarding the age at start of supplementation, the dosage and compliance were obtained from the mothers with face-to-face interview. Serum 25-hydroxy vitamin D (25-OH-D), alkaline phosphatase (AP), parathormone (PTH) levels were measured.</p> <p>Results</p> <p>The mean age at which Vitamin D3 supplementation began was 16.5 ± 20.7 (3-120) days. Ninety percent of cases (n:76) were receiving 3 drops (400 IU) vitamin D3 per day as recommended; 70% of cases (n:59) were given vitamin D3 regularly, the remainder had imperfect compliance. Among those children who are older than 12 months, only 20% continued vitamin D supplementation. No subject had clinical signs of rickets. The mean 25-OH-D level was 42,5 ± 25,8 (median: 38.3) ng/ml. Ten subjects (12%) had their serum 25-OH-D levels lower than 20 ng/ml (6 between 15-20 ng/ml, 3 between 5-15 ng/ml and only one < 5 ng/ml).</p> <p>Conclusions</p> <p>400 U/day vitamin D seems adequate to prevent vitamin D deficiency. However, we believe that the program for preventing vitamin D deficiency in Turkey, needs to be reinforced to start immediately after birth, and to continue beyond 1 year of age at 400U regular daily dosage.</p
Dapsone induced cholangitis as a part of dapsone syndrome: a case report
BACKGROUND: Dapsone can rarely cause a hypersensitivity reaction called dapsone syndrome, consisting of fever, hepatitis, exfoliative dermatitis, lymphadenopathy and hemolytic anemia. Dapsone syndrome is a manifestation of the DRESS (drug rash with eosinophilia and systemic symptoms) syndrome which is a serious condition that has been reported in association with various drugs. Cholangitis in dapsone syndrome has not been reported so far in the world literature. CASE PRESENTATION: We report a patient who presented with fever, exfoliative dermatitis, jaundice and anemia within three weeks of starting of dapsone therapy. These features are typical of dapsone syndrome, which is due to dapsone hypersensitivity and is potentially fatal. Unlike previous reports of hepatitic or cholestatic injury in dapsone syndrome we report here a case that had cholangitic liver injury. It responded to corticosteroids. CONCLUSION: We conclude that cholangitis, though unusual, can also form a part of dapsone syndrome. Physicians should be aware of this unusual picture of potentially fatal dapsone syndrome
A Cross-Sectional Study of HPV Vaccine Acceptability in Gaborone, Botswana
Background
Cervical cancer is the most common cancer among women in Botswana and elsewhere in Sub-Saharan Africa. We sought to examine whether HPV vaccine is acceptable among parents in Botswana, which recently licensed the vaccine to prevent cervical cancer. Methods and Findings
We conducted a cross-sectional survey in 2009, around the time the vaccine was first licensed, with adults recruited in general medicine and HIV clinics in Gaborone, the capital of Botswana. Although only 9% (32/376) of respondents had heard of HPV vaccine prior to the survey, 88% (329/376) said they definitely will have their adolescent daughters receive HPV vaccine. Most respondents would get the vaccine for their daughters at a public or community clinic (42%) or a gynecology or obstetrician\u27s office (39%), and 74% would get it for a daughter if it were available at her school. Respondents were more likely to say that they definitely will get HPV vaccine for their daughters if they had less education (OR = 0.20, 95% CI = 0.07–0.58) or lived more than 30 kilometers from the capital, Gaborone (OR = 2.29, 95% CI = 1.06–4.93). Other correlates of acceptability were expecting to be involved in the decision to get HPV vaccine, thinking the vaccine would be hard to obtain, and perceiving greater severity of HPV-related diseases. Conclusions
HPV vaccination of adolescent girls would be highly acceptable if the vaccine became widely available to the daughters of healthcare seeking parents in Gaborone, Botswana. Potential HPV vaccination campaigns should provide more information about HPV and the vaccine as well as work to minimize barriers
Mitochondrial DNA deletions in muscle satellite cells: implications for therapies.
Progressive myopathy is a major clinical feature of patients with mitochondrial DNA (mtDNA) disease. There is limited treatment available for these patients although exercise and other approaches to activate muscle stem cells (satellite cells) have been proposed. The majority of mtDNA defects are heteroplasmic (a mixture of mutated and wild-type mtDNA present within the muscle) with high levels of mutated mtDNA and low levels of wild-type mtDNA associated with more severe disease. The culture of satellite cell-derived myoblasts often reveals no evidence of the original mtDNA mutation although it is not known if this is lost by selection or simply not present in these cells. We have explored if the mtDNA mutation is present in the satellite cells in one of the commonest genotypes associated with mitochondrial myopathies (patients with single, large-scale mtDNA deletions). Analysis of satellite cells from eight patients showed that the level of mtDNA mutation in the satellite cells is the same as in the mature muscle but is most often subsequently lost during culture. We show that there are two periods of selection against the mutated form, one early on possibly during satellite cell activation and the other during the rapid replication phase of myoblast culture. Our data suggest that the mutations are also lost during rapid replication in vivo, implying that strategies to activate satellite cells remain a viable treatment for mitochondrial myopathies in specific patient groups
Causal Loop Analysis of coastal geomorphological systems
As geomorphologists embrace ever more sophisticated theoretical frameworks that shift from simple notions of evolution towards single steady equilibria to recognise the possibility of multiple response pathways and outcomes, morphodynamic modellers are facing the problem of how to keep track of an ever-greater number of system feedbacks. Within coastal geomorphology, capturing these feedbacks is critically important, especially as the focus of activity shifts from reductionist models founded on sediment transport fundamentals to more synthesist ones intended to resolve emergent behaviours at decadal to centennial scales. This paper addresses the challenge of mapping the feedback structure of processes controlling geomorphic system behaviour with reference to illustrative applications of Causal Loop Analysis at two study cases: (1) the erosion–accretion behaviour of graded (mixed) sediment beds, and (2) the local alongshore sediment fluxes of sand-rich shorelines. These case study examples are chosen on account of their central role in the quantitative modelling of geomorphological futures and as they illustrate different types of causation. Causal loop diagrams, a form of directed graph, are used to distil the feedback structure to reveal, in advance of more quantitative modelling, multi-response pathways and multiple outcomes. In the case of graded sediment bed, up to three different outcomes (no response, and two disequilibrium states) can be derived from a simple qualitative stability analysis. For the sand-rich local shoreline behaviour case, two fundamentally different responses of the shoreline (diffusive and anti-diffusive), triggered by small changes of the shoreline cross-shore position, can be inferred purely through analysis of the causal pathways. Explicit depiction of feedback-structure diagrams is beneficial when developing numerical models to explore coastal morphological futures. By explicitly mapping the feedbacks included and neglected within a model, the modeller can readily assess if critical feedback loops are included
Reducing inappropriate polypharmacy: the process of deprescribing
Inappropriate polypharmacy, especially in older people, imposes a substantial burden of adverse drug events, ill health, disability, hospitalization, and even death. The single most important predictor of inappropriate prescribing and risk of adverse drug events in older patients is the number of prescribed drugs. Deprescribing is the process of tapering or stopping drugs, aimed at minimizing polypharmacy and improving patient outcomes. Evidence of efficacy for deprescribing is emerging from randomized trials and observational studies. A deprescribing protocol is proposed comprising 5 steps: (1) ascertain all drugs the patient is currently taking and the reasons for each one; (2) consider overall risk of drug-induced harm in individual patients in determining the required intensity of deprescribing intervention; (3) assess each drug in regard to its current or future benefit potential compared with current or future harm or burden potential; (4) prioritize drugs for discontinuation that have the lowest benefit-harm ratio and lowest likelihood of adverse withdrawal reactions or disease rebound syndromes; and (5) implement a discontinuation regimen and monitor patients closely for improvement in outcomes or onset of adverse effects. Whereas patient and prescriber barriers to deprescribing exist, resources and strategies are available that facilitate deliberate yet judicious deprescribing and deserve wider application
Search for CP Violation in the Decay Z -> b (b bar) g
About three million hadronic decays of the Z collected by ALEPH in the years
1991-1994 are used to search for anomalous CP violation beyond the Standard
Model in the decay Z -> b \bar{b} g. The study is performed by analyzing
angular correlations between the two quarks and the gluon in three-jet events
and by measuring the differential two-jet rate. No signal of CP violation is
found. For the combinations of anomalous CP violating couplings, and , limits of \hat{h}_b < 0.59h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st
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