187 research outputs found
Unilateral Lower Limb Swelling Secondary to Cavernous Lymphangioma
IntroductionWe report an unusual case of unilateral leg swelling secondary to cavernous lymphangioma (cystic hygroma), which normally affects the head and neck regions.Case reportA 25 year gentleman presented to our department with a 13-year history of gradually increasing unilateral leg swelling and recurrent infections. Investigations showed appearances consistent with cavernous lymphangioma, and partial excision of the lesion led to resolution of symptoms.DiscussionThe most common sites for cystic hygroma are the head and neck areas, but the extremities can be affected as demonstrated. Complete surgical excision is often difficult, and there is a tendency for recurrence.This case acts as an illustration of an uncommon yet important cause for unilateral leg swelling
Conservative Management of Type 2 Endoleaks is not Associated with Increased Risk of Aneurysm Rupture
AbstractObjectiveEndovascular repair (EVAR) of abdominal aortic aneurysms (AAAs) has led to a reduction in the perioperative mortality when compared with open repair. However, re-intervention for complications, such as endoleak, may be required in up to 20% of the cases. Controversy exists over the management of Type 2 endoleaks. This study examined the outcomes of patients with Type 2 endoleaks treated conservatively to inform the ongoing management debate.MethodsAll patients with a confirmed Type 2 endoleak after EVAR for an infrarenal AAA were included in the study. Data regarding device details, endoleak and time point, aneurysm sac growth, intervention and outcome were collected retrospectively from case notes and the vascular research database.ResultsForty-one Type 2 endoleaks were seen in 369 EVARs performed for infrarenal AAA between March 1994 and June 2006. Twenty-five were isolated Type 2 endoleaks and 16 occurred in conjunction with other endoleaks. Of the 25 isolated Type 2 endoleaks, 18 (72%) patients demonstrated no increase in sac size, six (24%) patients showed an enlargement of the sac and one patient was lost to follow-up. Only one patient underwent intervention for an isolated Type 2 endoleak. After a mean follow-up period of 4 years, approximately half of the patients (48%) remain under observation (with an enlarging or stable sac), whilst the others (48%) have spontaneously sealed. Only five patients under surveillance (20%) have an enlarging sac. There were no ruptured aneurysms or aneurysm-related deaths and no patients required conversion to open repair.ConclusionsIn this study, a policy of regular surveillance for Type 2 endoleaks was not associated with any adverse events. We therefore advocate the conservative approach for Type 2 endoleaks
Statistical Model of Superconductivity in a 2D Binary Boson-Fermion Mixture
A two-dimensional (2D) assembly of noninteracting, temperature-dependent,
composite-boson Cooper pairs (CPs) in chemical and thermal equilibrium with
unpaired fermions is examined in a binary boson-fermion statistical model as
the superconducting singularity temperature is approached from above. The model
is derived from {\it first principles} for the BCS model interfermion
interaction from three extrema of the system Helmholtz free energy (subject to
constant pairable-fermion number) with respect to: a) the pairable-fermion
distribution function; b) the number of excited (bosonic) CPs, i.e., with
nonzero total momenta--usually ignored in BCS theory--and with the appropriate
(linear, as opposed to quadratic) dispersion relation that arises from the
Fermi sea; and c) the number of CPs with zero total momenta. Compared with the
BCS theory condensate, higher singularity temperatures for the Bose-Einstein
condensate are obtained in the binary boson-fermion mixture model which are in
rough agreement with empirical critical temperatures for quasi-2D
superconductorsComment: 16 pages and 4 figures. This is a improved versio
Comparison of soft and hard tissue ablation with sub-ps and ns pulse lasers
Tissue ablation with ultrashort laser pulses offers several unique advantages. The nonlinear energy deposition is insensitive to tissue type, allowing this tool to be used for soft and hard tissue ablation. The localized energy deposition lead to precise ablation depth and minimal collateral damage. This paper reports on efforts to study and demonstrate tissue ablation using an ultrashort pulse laser. Ablation efficiency and extent of collateral damage for 0.3 ps and 1000 ps duration laser pulses are compared. Temperature measurements of the rear surface of a tooth section is also presented
Generalized Bose-Einstein Condensation
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing
simultaneously in multiple states. We review examples of the three types in an
ideal Bose gas with different geometries. In Type I there is a discrete number
of quantum states each having macroscopic occupation; Type II has condensation
into a continuous band of states, with each state having macroscopic
occupation; in Type III each state is microscopically occupied while the entire
condensate band is macroscopically occupied. We begin by discussing Type I or
"normal" BEC into a single state for an isotropic harmonic oscillator
potential. Other geometries and external potentials are then considered: the
{}"channel" potential (harmonic in one dimension and hard-wall in the other),
which displays Type II, the {}"cigar trap" (anisotropic harmonic potential),
and the "Casimir prism" (an elongated box), the latter two having Type III
condensations. General box geometries are considered in an appendix. We
particularly focus on the cigar trap, which Van Druten and Ketterle first
showed had a two-step condensation: a GBEC into a band of states at a
temperature and another "one-dimensional" transition at a lower
temperature into the ground state. In a thermodynamic limit in which
the ratio of the dimensions of the anisotropic harmonic trap is kept fixed,
merges with the upper transition, which then becomes a normal BEC.
However, in the thermodynamic limit of Beau and Zagrebnov, in which the ratio
of the boundary lengths increases exponentially, becomes fixed at the
temperature of a true Type I phase transition. The effects of interactions on
GBEC are discussed and we show that there is evidence that Type III
condensation may have been observed in the cigar trap.Comment: 17 pages; 6 figures. Intended for American Journal of Physic
Genome-Wide Joint Meta-Analysis of SNP and SNP-by-Smoking Interaction Identifies Novel Loci for Pulmonary Function
Genome-wide association and Mendelian randomisation analysis provide insights into the pathogenesis of heart failure
Heart failure (HF) is a leading cause of morbidity and mortality worldwide. A small proportion of HF cases are attributable to monogenic cardiomyopathies and existing genome-wide association studies (GWAS) have yielded only limited insights, leaving the observed heritability of HF largely unexplained. We report results from a GWAS meta-analysis of HF comprising 47,309 cases and 930,014 controls. Twelve independent variants at 11 genomic loci are associated with HF, all of which demonstrate one or more associations with coronary artery disease (CAD), atrial fibrillation, or reduced left ventricular function, suggesting shared genetic aetiology. Functional analysis of non-CAD-associated loci implicate genes involved in cardiac development (MYOZ1, SYNPO2L), protein homoeostasis (BAG3), and cellular senescence (CDKN1A). Mendelian randomisation analysis supports causal roles for several HF risk factors, and demonstrates CAD-independent effects for atrial fibrillation, body mass index, and hypertension. These findings extend our knowledge of the pathways underlying HF and may inform new therapeutic strategies
Associations of autozygosity with a broad range of human phenotypes
In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (F-ROH) for >1.4 million individuals, we show that F-ROH is significantly associated (p <0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: F-ROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of F-ROH are confirmed within full-sibling pairs, where the variation in F-ROH is independent of all environmental confounding.Peer reviewe
Reproducibility in the absence of selective reporting : An illustration from large-scale brain asymmetry research
Altres ajuts: Max Planck Society (Germany).The problem of poor reproducibility of scientific findings has received much attention over recent years, in a variety of fields including psychology and neuroscience. The problem has been partly attributed to publication bias and unwanted practices such as p-hacking. Low statistical power in individual studies is also understood to be an important factor. In a recent multisite collaborative study, we mapped brain anatomical left-right asymmetries for regional measures of surface area and cortical thickness, in 99 MRI datasets from around the world, for a total of over 17,000 participants. In the present study, we revisited these hemispheric effects from the perspective of reproducibility. Within each dataset, we considered that an effect had been reproduced when it matched the meta-analytic effect from the 98 other datasets, in terms of effect direction and significance threshold. In this sense, the results within each dataset were viewed as coming from separate studies in an "ideal publishing environment," that is, free from selective reporting and p hacking. We found an average reproducibility rate of 63.2% (SD = 22.9%, min = 22.2%, max = 97.0%). As expected, reproducibility was higher for larger effects and in larger datasets. Reproducibility was not obviously related to the age of participants, scanner field strength, FreeSurfer software version, cortical regional measurement reliability, or regional size. These findings constitute an empirical illustration of reproducibility in the absence of publication bias or p hacking, when assessing realistic biological effects in heterogeneous neuroscience data, and given typically-used sample sizes
Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: A systematic analysis for the Global Burden of Disease Study 2015
Background: The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context.
Methods: We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI).
Findings: Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa.
Interpretation: Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden.
Funding: Bill & Melinda Gates Foundation
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