2,742 research outputs found
Phylogenetic analysis of cytochrome c oxidase I sequences to determine higher-level relationships within the coleoid cephalopods
Until recently, the higher-level phylogenetic relationships of coleoid cephalopods have remained unclear. A thorough knowledge of the higher-level phylogeny of the group has been limited by the paucity of paleontological data for this poorly-fossilized group and the lack of cladistic analyses of developmental, morphological, and molecular data applied to the coleoids. In this study we analyzed a 657 base pair portion of the mitochondrial cytochrome c oxidase I (COI) gene from 48 cephalopod species representing a broad spectrum of coleoid diversity to examine higher-level phylogenetic relationships within the group. The COI gene exhibited a high degree of nucleotide sequence variability, with one half of the sites varying in at least one taxon. COI amino acid sequences were highly conserved, but were useful in determining basal-level relationships among the Coleoidea. The evolutionary rate of COI amino acid sequences differed significantly between the two main lineages. The average amino acid sequence divergence within the Octopodiformes was over twice that of the average divergence within the decapods. In addition to analysis of the unweighted data set, phylogenetic analysis was conducted on the data subjected to a single round of rescaled consistency index (RCI) weighting to reduce the effect of homoplasious substitutions in determining phylogenetic structure. To further reduce the influence of homoplastic change and to facilitate bootstrap analysis of the data, a nested analysis of the data was employed, beginning with an analysis of the entire data set to determine proper outgroups to be used in the more restrictive analysis of the decapods and octopods separately. We draw the following conclusions from our analysis of cephalopod COI sequences: (I) the Coleoidea, Octopoda, Vampyromorpha, and Decapoda are monophyletic groups; (2) the Vampyromorpha and Octopoda are sister groups; (3) the Sepioidea, as including the five families Spirulidae, Sepiolidae, Sepiidae, Sepiadariidae, and Idiosepiidae, is polyphyletic; (4) Spirula is more closely related to the Teuthoidea than it is to the remaining members of the Sepioidea; and (5) the Oegopsida, as currently defined is polyphyletic
Supermassive black holes do not correlate with dark matter halos of galaxies
Supermassive black holes have been detected in all galaxies that contain
bulge components when the galaxies observed were close enough so that the
searches were feasible. Together with the observation that bigger black holes
live in bigger bulges, this has led to the belief that black hole growth and
bulge formation regulate each other. That is, black holes and bulges
"coevolve". Therefore, reports of a similar correlation between black holes and
the dark matter halos in which visible galaxies are embedded have profound
implications. Dark matter is likely to be nonbaryonic, so these reports suggest
that unknown, exotic physics controls black hole growth. Here we show - based
in part on recent measurements of bulgeless galaxies - that there is almost no
correlation between dark matter and parameters that measure black holes unless
the galaxy also contains a bulge. We conclude that black holes do not correlate
directly with dark matter. They do not correlate with galaxy disks, either.
Therefore black holes coevolve only with bulges. This simplifies the puzzle of
their coevolution by focusing attention on purely baryonic processes in the
galaxy mergers that make bulges.Comment: 12 pages, 9 Postscript figures, 1 table; published in Nature (20
January 2011
Comments on John D. Keen and James E. Keen, What is the point: will screening mammography save my life? BMC Medical Informatics and Decision Making, 2009
This paper by John D. Keen and James E. Keen addresses a thorny subject. The numerical findings and commentaries in their paper will be disturbing to some readers and seem to defy logic and well established viewpoints. It may well generate angry letters to the editor. However such numerical analysis and reporting including civil discussion should be welcomed and are the basis for informed decision making – something that is highly needed in this field
Double valve replacement for acute spontaneous left chordal rupture secondary to chronic aortic incompetence
A 54 years old male with undiagnosed chronic calcific degenerative aortic valve incompetence presented with acute left anterior chordae tendinae rupture resulting in severe left heart failure and cardiogenic shock. He was successfully treated with emergency double valve replacement using mechanical valves. The pathogenesis of acute rupture of the anterior chordae tendinae, without any evidence of infective endocarditis or ischemic heart disease seems to have been attrition of the subvalvular mitral apparatus by the chronic regurgitant jet of aortic incompetence with chronic volume overload. We review the literature with specific focus on the occurrence of this unusual event
New Experimental Limits on Macroscopic Forces Below 100 Microns
Results of an experimental search for new macroscopic forces with Yukawa
range between 5 and 500 microns are presented. The experiment uses 1 kHz
mechanical oscillators as test masses with a stiff conducting shield between
them to suppress backgrounds. No signal is observed above the instrumental
thermal noise after 22 hours of integration time. These results provide the
strongest limits to date between 10 and 100 microns, improve on previous limits
by as much as three orders of magnitude, and rule out half of the remaining
parameter space for predictions of string-inspired models with low-energy
supersymmetry breaking. New forces of four times gravitational strength or
greater are excluded at the 95% confidence level for interaction ranges between
200 and 500 microns.Comment: 25 Pages, 7 Figures: Minor Correction
Comparison of the CDC Backpack aspirator and the Prokopack aspirator for sampling indoor- and outdoor-resting mosquitoes in southern Tanzania.
BACKGROUND\ud
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Resting mosquitoes can easily be collected using an aspirating device. The most commonly used mechanical aspirator is the CDC Backpack aspirator. Recently, a simple, and low-cost aspirator called the Prokopack has been devised and proved to have comparable performance. The following study evaluates the Prokopack aspirator compared to the CDC backpack aspirator when sampling resting mosquitoes in rural Tanzania.\ud
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METHODS\ud
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Mosquitoes were sampled in- and outdoors of 48 typical rural African households using both aspirators. The aspirators were rotated between collectors and households in a randomized, Latin Square design. Outdoor collections were performed using artificial resting places (large barrel and car tyre), underneath the outdoor kitchen (kibanda) roof and from a drop-net. Data were analysed with generalized linear models.\ud
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RESULTS\ud
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The number of mosquitoes collected using the CDC Backpack and the Prokopack aspirator were not significantly different both in- and outdoors (indoors p = 0.735; large barrel p = 0.867; car tyre p = 0.418; kibanda p = 0.519). The Prokopack was superior for sampling of drop-nets due to its smaller size. The number mosquitoes collected per technician was more consistent when using the Prokopack aspirator. The Prokopack was more user-friendly: technicians preferred using the it over the CDC backpack aspirator as it weighs considerably less, retains its charge for longer and is easier to manoeuvre.\ud
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CONCLUSIONS\ud
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The Prokopack proved in the field to be more advantageous than the CDC Backpack aspirator. It can be self assembled using simple, low-cost and easily attainable materials. This device is a useful tool for researchers or vector-control surveillance programs operating in rural Africa, as it is far simpler and quicker than traditional means of sampling resting mosquitoes. Further longitudinal evaluations of the Prokopack aspirator versus the gold standard pyrethrum spray catch for indoor resting catches are recommended
First report of the presence of hepatitis E virus in Scottish harvested shellfish purchased at retail level
Burden of podoconiosis in poor rural communities in Guliso woreda, western Ethiopia
Background. Podoconiosis is an environmental lymphoedema affecting people living and working barefoot on irritant red clay soil. Podoconiosis is relatively well described in southern Ethiopia, but remains neglected in other parts of the Ethiopian highlands. This study aimed to assess the burden of podoconiosis in rural communities in western Ethiopia.
Methodology/Principal Findings. A cross-sectional study was conducted in Gulliso woreda (district), west Ethiopia. A household survey in the 26 rural kebeles (villages) of this district was conducted to identify podoconiosis patients and to measure disease prevalence. A more detailed study was done in six randomly selected kebeles to describe clinical features of the disease, patients’ experiences of foot hygiene, and shoe wearing practice. 1,935 cases of podoconiosis were registered, giving a prevalence of 2.8%. The prevalence was higher in those aged 15 – 64 years (5.2%) and in females than males (prevalence ratio 2.6:1). 90.3% of patients were in the 15 – 64 year age group. In the detailed study, 335 cases were interviewed and their feet assessed. The majority of patients were farmers, uneducated, and poor. Two-third of patients developed the disease before the age of thirty. Almost all patients (97.0%) had experienced adenolymphangitis (ALA - red, hot legs, swollen and painful groin) at least once during the previous year. Patients experienced an average of 5.5 ALA episodes annually, each of average 4.4 days, thus 24 working days were lost annually. The incidence of ALA in podoconiosis patients was higher than that reported for filariasis in other countries. Shoe wearing was limited mainly due to financial problems.
Conclusions. We have documented high podoconiosis prevalence, frequent adenolymphangitis and high disease-related morbidity in west Ethiopia. Interventions must be developed to prevent, treat and control podoconiosis, one of the core neglected tropical diseases in Ethiopia
APP metabolism regulates tau proteostasis in human cerebral cortex neurons.
Accumulation of Aβ peptide fragments of the APP protein and neurofibrillary tangles of the microtubule-associated protein tau are the cellular hallmarks of Alzheimer's disease (AD). To investigate the relationship between APP metabolism and tau protein levels and phosphorylation, we studied human-stem-cell-derived forebrain neurons with genetic forms of AD, all of which increase the release of pathogenic Aβ peptides. We identified marked increases in intracellular tau in genetic forms of AD that either mutated APP or increased its dosage, suggesting that APP metabolism is coupled to changes in tau proteostasis. Manipulating APP metabolism by β-secretase and γ-secretase inhibition, as well as γ-secretase modulation, results in specific increases and decreases in tau protein levels. These data demonstrate that APP metabolism regulates tau proteostasis and suggest that the relationship between APP processing and tau is not mediated solely through extracellular Aβ signaling to neurons.This research
was supported by grants from Alzheimer’s Research UK and the Wellcome
Trust (to F.J.L.) and core funding to the Gurdon Trust from the Wellcome Trust
and Cancer Research UK. N.S. was supported by a Woolf-Fisher Trust (NZ)
PhD studentship. H.Z. was supported by the Wolfson Centre at UCL, and
the UCLH Dementia BRU provided financial support for the collection of patient
materials. F.J.L. is a Wellcome Trust Senior Investigator, K.B. is a
Torsten So¨ derberg Academy Professor, and H.Z. is a Wallenberg Academy
Fellow.This is the final version. It was first published by Elsevier at http://www.sciencedirect.com/science/article/pii/S2211124715003599
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