2,783 research outputs found
Testing Robustness of WMAP Temperature Calibration to Timing Offsets
Results derived from data obtained by Wilkinson Microwave Anisotropy Probe (WMAP) are extensively used in many areas of physics. It has been claimed recently that the published WMAP calibrated data and maps might be in question because of an undocumented timing offset in the official processing pipeline [The origin of the WMAP quadrupole, Hao Liu, Shao-Lin Xiong, Ti-Pei Li]. This timing error was shown to induce a quadrupole pattern in the final maps that is very similar to the officially published quadrupole mode. It is clear that a timing offset at the map-making stage will strongly affect the quadrupole scale, since the map-making in [The origin of the WMAP quadrupole, Hao Liu, Shao-Lin Xiong, Ti-Pei Li] was based on the official WMAP calibrated TOD. But there is also a possibility that the calibration process itself could be affected as well and we test this here. In this work we approximately reproduce the original dipole-based iterative calibration procedure to produce a calibrated data set starting from raw uncalibrated data. Using the calibrated data we generate a set of sky maps that we compare to the officially released maps and note some differences between our and official results. We also investigate the effects of various timing offsets introduced in the calibration stage on the final products. We find that a timing offset in the calibration process has little effect on the calibrated data and induced quadrupole
Prevalence of donor-transmitted atherosclerosis—Clinical utility of intracoronary ultrasound early after heart transplantation. A single-center study
AbstractIntroductionCoronary allograft vasculopathy (CAV) is one of the main factors limiting long-term survival following orthotopic heart transplantation (HTx). Whether or not and, if so, how donor-transmitted atherosclerosis (DCA) affects the post-transplant course of the allograft recipient is still unclear. Conventional coronary angiography is a moderately accurate technique for DCA detection as it will reveal only the more gross morphological lesions. By contrast, intravascular ultrasound (IVUS) has been shown to be a much more sensitive technique for CAV and DCA detection. In our study we sought to determine the prevalence of DCA in our HTx patient population and identify main risk factors of DCA based on donor characteristics.Patients and methodsWe performed a retrospective analysis of data of 119 patients (92 men, 27 women) undergoing transplantation in our center from August 2006 through September 2012, who had survived their first post-transplant month and had coronary angiography and IVUS.ResultsDCA was present in 39 patients, and not documented in 80 patients. The main risk factors for DCA included donor age, cigarette smoking, and hypertension; the other parameters were not shown to be statistically significant. In-hospital mortality was low in both groups (DCA positive and DCA negative), with one patient dying in either group. One-year mortality rates post-HTx were likewise almost identical in both groups (15.4% and 15% in DCA positive and negative, respectively).ConclusionThe prevalence of DCA in our patients was 32.8%, with major risk factors for DCA including donor age, cigarette smoking, and hypertension. As age seems to be the strongest predictor, coronary angiography should be a routine examination in individuals aged over 40 years; the examination should be considered in younger individuals with a cluster of several of risk factors. The 1-year survival in this selected patient population was identical in both groups, the implication being that the diagnosis of DCA had no effect on 1-year survival post-HTx
Large and uniform optical emission shifts in quantum dots externally strained along their growth axis
We introduce a method which enables to directly compare the impact of elastic
strain on the optical properties of distinct quantum dots (QDs). Specifically,
the QDs are integrated in a cross-section of a semiconductor core wire which is
surrounded by an amorphous straining shell. Detailed numerical simulations show
that, thanks to the mechanical isotropy of the shell, the strain field in a
core section is homogeneous. Furthermore, we use the core material as an in
situ strain gauge, yielding reliable values for the emitter energy tuning
slope. This calibration technique is applied to self-assembled InAs QDs
submitted to incremental tensile strain along their growth axis. In contrast to
recent studies conducted on similar QDs stressed perpendicularly to their
growth axis, optical spectroscopy reveals 5-10 times larger tuning slopes, with
a moderate dispersion. These results highlight the importance of the stress
direction to optimise QD response to applied strain, with implications both in
static and dynamic regimes. As such, they are in particular relevant for the
development of wavelength-tunable single photon sources or hybrid QD
opto-mechanical systems
dsRNA expression in the mouse elicits RNAi in oocytes and low adenosine deamination in somatic cells
Double-stranded RNA (dsRNA) can enter different pathways in mammalian cells, including sequence-specific RNA interference (RNAi), sequence-independent interferon (IFN) response and editing by adenosine deaminases. To study the routing of dsRNA to these pathways in vivo, we used transgenic mice ubiquitously expressing from a strong promoter, an mRNA with a long hairpin in its 3′-UTR. The expressed dsRNA neither caused any developmental defects nor activated the IFN response, which was inducible only at high expression levels in cultured cells. The dsRNA was poorly processed into siRNAs in somatic cells, whereas, robust RNAi effects were found in oocytes, suggesting that somatic cells lack some factor(s) facilitating siRNA biogenesis. Expressed dsRNA did not cause transcriptional silencing in trans. Analysis of RNA editing revealed that a small fraction of long dsRNA is edited. RNA editing neither prevented the cytoplasmic localization nor processing into siRNAs. Thus, a long dsRNA structure is well tolerated in mammalian cells and is mainly causing a robust RNAi response in oocyte
Impact of trees and forests on the Devonian landscape and weathering processes with implications to the global Earth's system properties – A critical review
Evolution of terrestrial plants, the first vascular plants, the first trees, and then whole forest ecosystems had far
reaching consequences for Earth system dynamics. These innovations are considered important moments in the
evolution of the atmosphere, biosphere, and oceans, even if the effects might have lagged by hundreds of
thousands or millions of years. These fundamental changes in the Earth's history happened in the Paleozoic: from
the Ordovician, the time of the first land plants, to the Carboniferous, dominated by forest ecosystems. The
Devonian Plant Hypothesis (DPH) was the first concept to offer a full and logical explanation of the many
environmental changes associated with the evolution of trees/forests that took place during this time period. The
DPH highlighted the impact of deep-rooted vascular plants, particularly trees on weathering processes, pedogenesis,
nutrient transport, CO2 cycling, organic and inorganic carbon deposition, and suggests further possible
consequences on the marine realm (oceanic anoxia and extinction during the Late Devonian). Here we attempt to
combine the DPH and the related expansion in biodiversity, the Devonian Plant Explosion (DePE), with the
Biogeomorphic Ecosystem Engineering (BEE) concept. This idea connects tree growth and activity with initiation
and/or alteration of geomorphic processes, and therefore the creation or deterioration of geomorphic landforms.
We focus on trees and forest ecosystems, as the assumed dominant driver of plant-initiated change. We find that
whereas there is a broad evidence of trees as important biogeomorphic ecosystem engineers, addressing the DPH
is difficult due to limited, difficult to interpret, or controversial data. However, we argue the concept of BEE does
shed new light on DPH and suggest new data sources that should be able to answer our main question: were
Devonian trees Biogeomorphic Ecosystem engineers
Ebola virus disease (EVD) outbreak re-emergence regulation in East Africa: preparedness and vaccination perspective
Sudan ebolavirus (SUDV), Bundibugyo ebolavirus, Taï Forest ebolavirus, and Zaire ebolavirus (EBOV) are the most potentially life-threatening and grievous species reported among the Ebolavirus genus. Previously, the most common cases pointed to EBOV as the primary causative agent of Ebolavirus epidemics and fatalities. From 2013 to 2016, a devastating EBOV outbreak in West Africa resulted in 29,000 illness cases, prompting WHO global member countries to prioritise vaccine candidates in the early stages of development. The impending spread of EBOV in Guinea, Uganda, and the Democratic Republic of the Congo highlighted the ongoing need for secure and effective vaccine programmes against emerging infections using the most secure deployment precautions and methodologies. The West Africa outbreak and all current outbreaks in other countries have been prevented through the effective immunisation of healthy individuals through vaccination and their interactions with identified patients, medical practitioners, and frontline emergency professionals. Despite the fact that EBOV outbreaks previously only infected a small percentage of the global population, they have occasionally caused widespread suffering and huge economic costs in endemic countries. Reported transmission of such viruses beyond nonendemic zones in conjunction with the bioweapon potentiality of ebolaviruses necessitates the discovery and production of EBOV vaccines globally.O
Nano-biochar: recent progress, challenges, and opportunities for sustainable environmental remediation
Biochar is a carbonaceous by-product of lignocellulosic biomass developed by various thermochemical processes. Biochar can be transformed into “nano-biochar” by size reduction to nano-meters level. Nano-biochar presents remarkable physico-chemical behavior in comparison to macro-biochar including; higher stability, unique nanostructure, higher catalytic ability, larger specific surface area, higher porosity, improved surface functionality, and surface active sites. Nano-biochar efficiently regulates the transport and absorption of vital micro-and macro-nutrients, in addition to toxic contaminants (heavy metals, pesticides, antibiotics). However an extensive understanding of the recent nano-biochar studies is essential for large scale implementations, including development, physico-chemical properties and targeted use. Nano-biochar toxicity on different organisms and its in-direct effect on humans is an important issue of concern and needs to be extensively evaluated for large scale applications. This review provides a detailed insight on nanobiochar research for (1) development methodologies, (2) compositions and properties, (3) characterization methods, (4) potentiality as emerging sorbent, photocatalyst, enzyme carrier for environmental application, and (5) environmental concerns
Rhizospheric bacteria: the key to sustainable heavy metal detoxification strategies
The increasing rate of industrialization, anthropogenic, and geological activities have expedited the release of heavy metals (HMs) at higher concentration in environment. HM contamination resulting due to its persistent nature, injudicious use poses a potential threat by causing metal toxicities in humans and animals as well as severe damage to aquatic organisms. Bioremediation is an emerging and reliable solution for mitigation of these contaminants using rhizospheric microorganisms in an environmentally safe manner. The strategies are based on exploiting microbial metabolism and various approaches developed by plant growth promoting bacteria (PGPB) to minimize the toxicity concentration of HM at optimum levels for the environmental clean-up. Rhizospheric bacteria are employed for significant growth of plants in soil contaminated with HM. Exploitation of bacteria possessing plant-beneficial traits as well as metal detoxifying property is an economical and promising approach for bioremediation of HM. Microbial cells exhibit different mechanisms of HM resistance such as active transport, extra cellular barrier, extracellular and intracellular sequestration, and reduction of HM. Tolerance of HM in microorganisms may be chromosomal or plasmid originated. Proteins such as MerT and MerA of mer operon and czcCBA, ArsR, ArsA, ArsD, ArsB, and ArsC genes are responsible for metal detoxification in bacterial cell. This review gives insights about the potential of rhizospheric bacteria in HM removal from various polluted areas. In addition, it also gives deep insights about different mechanism of action expressed by microorganisms for HM detoxification. The dual-purpose use of biological agent as plant growth enhancement and remediation of HM contaminated site is the most significant future prospect of this article
Stretching the Rules: Monocentric Chromosomes with Multiple Centromere Domains
The centromere is a functional chromosome domain that is essential for faithful chromosome segregation during cell division and that can be reliably identified by the presence of the centromere-specific histone H3 variant CenH3. In monocentric chromosomes, the centromere is characterized by a single CenH3-containing region within a morphologically distinct primary constriction. This region usually spans up to a few Mbp composed mainly of centromere-specific satellite DNA common to all chromosomes of a given species. In holocentric chromosomes, there is no primary constriction; the centromere is composed of many CenH3 loci distributed along the entire length of a chromosome. Using correlative fluorescence light microscopy and high-resolution electron microscopy, we show that pea (Pisum sativum) chromosomes exhibit remarkably long primary constrictions that contain 3-5 explicit CenH3-containing regions, a novelty in centromere organization. In addition, we estimate that the size of the chromosome segment delimited by two outermost domains varies between 69 Mbp and 107 Mbp, several factors larger than any known centromere length. These domains are almost entirely composed of repetitive DNA sequences belonging to 13 distinct families of satellite DNA and one family of centromeric retrotransposons, all of which are unevenly distributed among pea chromosomes. We present the centromeres of Pisum as novel ``meta-polycentric'' functional domains. Our results demonstrate that the organization and DNA composition of functional centromere domains can be far more complex than previously thought, do not require single repetitive elements, and do not require single centromere domains in order to segregate properly. Based on these findings, we propose Pisum as a useful model for investigation of centromere architecture and the still poorly understood role of repetitive DNA in centromere evolution, determination, and function
A novel fusion model of hand-crafted features with deep convolutional neural networks for classification of several chest diseases using X-ray images
With the continuing global pandemic of coronavirus (COVID-19) sickness, it is critical to
seek diagnostic approaches that are both effective and rapid to limit the number of people infected with the
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The results of recent research suggest that
radiological images include important information related to COVID-19 and other chest diseases. As a result,
the use of deep learning (DL) to assist in the automated diagnosis of chest diseases may prove useful as a
diagnostic tool in the future. In this study, we propose a novel fusion model of hand-crafted features with
deep convolutional neural networks (DCNNs) for classifying ten different chest diseases such as COVID-19,
lung cancer (LC), atelectasis (ATE), consolidation lung (COL), tuberculosis (TB), pneumothorax (PNET),
edema (EDE), pneumonia (PNEU), pleural thickening (PLT), and normal using chest X-rays (CXR). The
method that has been suggested is split down into three distinct parts. The first step involves utilizing the
Info-MGAN network to perform segmentation on the raw CXR data to construct lung images of ten different
chest diseases. In the second step, the segmented lung images are fed into a novel pipeline that extracts
discriminatory features by using hand-crafted techniques such as SURF and ORB, and then these extracted
features are fused to the trained DCNNs. At last, various machine learning (ML) models have been used as
the last layer of the DCNN models for the classification of chest diseases. Comparison is made between the
performance of various proposed architectures for classification, all of which integrate DCNNs, key point
extraction methods, and ML models. We were able to attain a classification accuracy of 98.20% for testing
by utilizing the VGG-19 model with a softmax layer in conjunction with the ORB technique. Screening
for COVID-19 and other lung ailments can be accomplished using the method that has been proposed. The
robustness of the model was further confirmed by statistical analyses of the datasets using McNemar’s and
ANOVA tests respectively.Web of Science11392683924
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