393 research outputs found
Synchrotron Emission from Dark Matter in Galactic Subhalos. A Look into the Smith Cloud
One of the key predictions of the WIMP paradigm for Dark Matter (DM) is that
DM particles can annihilate into charged particles. These annihilations will
proceed in e.g. Galactic subhalos such as dwarf Galaxies or, as recently
pointed out, high velocity clouds such as the "Smith Cloud". In this note, we
focus on the radio emission associated with DM annihilations into electrons and
positrons occurring in the Smith Cloud. The phenomenology of this emission is
discussed in quite some detail. We argue that the uncertainties in the
propagation can be captured by the typical diffusion-loss length parameter
(Syrovatskii variable) but that the angle-integrated radio fluxes are
independent of the propagation. We conclude that if the Smith Cloud is indeed
dominated by DM, radio signals from DM annihilation stand out amongst other
messengers. Furthermore, low frequencies such as the ones observed by e.g. the
Low Frequency Array (LOFAR) and the next-generation Square Kilometre Array
(SKA) are optimal for searches for DM in the Smith Cloud. As a practical
application, we set conservative constraints on dark matter annihilation cross
section using data of continuum radio emission from the Galaxy at 22 MHz and at
1.4 GHz. Stronger constraints could be reached by background subtraction,
exploiting the profile and frequency dependence of the putative DM signal. We
set stronger but tentative limits using the median noise in brightness
temperature from the Green Bank Telescope and the LOFAR sensitivities.Comment: 23 pages, 17 figures. Extended discussion on how the limits/forecasts
are obtained. Matches published versio
Identification of Novel Fibrosis Modifiers by In Vivo siRNA Silencing.
Fibrotic diseases contribute to 45% of deaths in the industrialized world, and therefore a better understanding of the pathophysiological mechanisms underlying tissue fibrosis is sorely needed. We aimed to identify novel modifiers of tissue fibrosis expressed by myofibroblasts and their progenitors in their disease microenvironment through RNA silencing in vivo. We leveraged novel biology, targeting genes upregulated during liver and kidney fibrosis in this cell lineage, and employed small interfering RNA (siRNA)-formulated lipid nanoparticles technology to silence these genes in carbon-tetrachloride-induced liver fibrosis in mice. We identified five genes, Egr2, Atp1a2, Fkbp10, Fstl1, and Has2, which modified fibrogenesis based on their silencing, resulting in reduced Col1a1 mRNA levels and collagen accumulation in the liver. These genes fell into different groups based on the effects of their silencing on a transcriptional mini-array and histological outcomes. Silencing of Egr2 had the broadest effects in vivo and also reduced fibrogenic gene expression in a human fibroblast cell line. Prior to our study, Egr2, Atp1a2, and Fkbp10 had not been functionally validated in fibrosis in vivo. Thus, our results provide a major advance over the existing knowledge of fibrogenic pathways. Our study is the first example of a targeted siRNA assay to identify novel fibrosis modifiers in vivo
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Leucine-rich repeat containing 8A (LRRC8A) is essential for T lymphocyte development and function
Lrrc8a is a ubiquitously expressed gene that encodes a leucine-rich repeat (LRR)–containing protein detected at higher levels on the surface of thymocytes than on other immune cells. We generated Lrrc8a−/− mice to investigate the role of LRRC8A in lymphocyte development and function. Lrrc8a−/− mice had increased prenatal and postnatal mortality, growth retardation, and multiple tissue abnormalities. Lrrc8a−/− mice displayed a modest block in B cell development but intact intrinsic B cell function. In contrast, both Lrrc8a−/− mice and Lrrc8a−/−→Rag2−/− bone marrow chimeras exhibited a severe cell-intrinsic block in early thymic development, with decreased proliferation and increased apoptosis of thymocytes, and impaired peripheral T cell function. Thymic epithelial cells expressed an LRRC8A ligand that was critical for double-negative to double-positive thymocyte differentiation and survival in vitro. LRRC8A constitutively associated with the GRB2–GAB2 complex and lymphocyte-specific protein tyrosine kinase (LCK) in thymocytes. LRRC8A ligation activated AKT via the LCK–ZAP–70–GAB2–PI3K pathway, and AKT phosphorylation was markedly reduced in the thymus of Lrrc8a−/− mice. These findings reveal an essential role for LRRC8A in T cell development, survival, and function
Two Dimensional Pseudo-Wiener Filtering in Ultrasonic Imaging for Nondestructive Evaluation Applications
This paper deals with the use of a two dimensional pseudo-Wiener filter for ultrasonic image enhancement. Experimental results are presented to demonstrate the effectiveness of the technique for the improvement of the lateral resolution and image enhancement of ultrasonic images in materials such as graphite/epoxy composites and stainless steel. The difficulties encountered in the implementation of the filter will be delineated. Methods of overcoming some of these ‘implementational hurdles’ will be suggested
Spectroscopic variability of two Oe stars
The Oe stars HD45314 and HD60848 have recently been found to exhibit very
different X-ray properties: whilst HD60848 has an X-ray spectrum and emission
level typical of most OB stars, HD45314 features a much harder and brighter
X-ray emission, making it a so-called gamma Cas analogue. Monitoring the
optical spectra could provide hints towards the origin of these very different
behaviours. We analyse a large set of spectroscopic observations of HD45314 and
HD60848, extending over 20 years. We further attempt to fit the H-alpha line
profiles of both stars with a simple model of emission line formation in a
Keplerian disk. Strong variations in the strengths of the H-alpha, H-beta, and
He I 5876 emission lines are observed for both stars. In the case of HD60848,
we find a time lag between the variations in the equivalent widths of these
lines. The emission lines are double peaked with nearly identical strengths of
the violet and red peaks. The H-alpha profile of this star can be successfully
reproduced by our model of a disk seen under an inclination of 30 degrees. In
the case of HD45314, the emission lines are highly asymmetric and display
strong line profile variations. We find a major change in behaviour between the
2002 outburst and the one observed in 2013. This concerns both the relationship
between the equivalent widths of the various lines and their morphologies at
maximum strength (double-peaked in 2002 versus single-peaked in 2013). Our
simple disk model fails to reproduce the observed H-alpha line profiles of
HD45314. Our results further support the interpretation that Oe stars do have
decretion disks similar to those of Be stars. Whilst the emission lines of
HD60848 are explained by a disk with a Keplerian velocity field, the disk of
HD45314 seems to have a significantly more complex velocity field that could be
related to the phenomenon that produces its peculiar X-ray emission.Comment: Accepted for Publication in A&
Illness perceptions and quality of life in patients with non-small-cell lung cancer
__Purpose:__ Examine illness perceptions, functional health and quality of life of lung cancer patients throughout chemotherapy treatment.
__Patients and Methods:__ Longitudinal design with baseline measure 12 days after the first chemotherapy and follow-up measure 3 months later, where illness perceptions (BIPQ), functional health, and quality of life (EORTC QLQ-C-30) were measured. A total of 21 patients with non-small-cell lung cancer took part. Non-parametric testing was performed given the pilot nature of the study and the associated relatively small sample size.
__Results:__ Small to medium changes in illness perceptions and functional health between the two measurement points were detected, with both becoming more positive. More negative illness perceptions at the beginning of the treatment were associated with less functioning and lower quality of life at both beginning and end of treatment.
__Conclusion:__ Addressing illness perceptions seems a clinically relevant approach in improving functioning and quality of life of patients with non-small-cell lung cancer
Association between duration of symptoms and severity of disease at first presentation to paediatric rheumatology: results from the Childhood Arthritis Prospective Study
Objectives. To study the association between disease severity at first presentation to paediatric rheumatology (PRh) and length of time since symptom onset in children recruited to the Childhood Arthritis Prospective Study
Österreichisches Projekt Grundlagen zur Züchtung, Vermehrung und Sorten-/Saatgutprüfung für den Biolandbau: Ergebnisübersicht
In the Austrian research project “Basic principles for breeding, multiplication and
variety testing for organic agriculture” (from 2004 until 2008) novel methods for the
assessment of the suitability of seed and cultivars for organic farming were developed
and evaluated by an interdisciplinary co-operation of researchers, breeders and
variety testers. Organic farming requires specific combinations of crop plant
characters, especially seed health and resistance against seed-borne diseases.
Another crucial feature is the competitive ability against weeds. Early development
was found to significantly increase the competitiveness of different crop plants.
Genotypic variation in characters necessary for an efficient utilisation of below-ground
resources was also investigated, e.g. interrelations between root development and
drought stress tolerance and between mycorrhiza formation and nutrient use
efficiency. Based on the results obtained in various cultivar trials, it can be concluded
that genotypes suitable for organic growing conditions may be pre-selected from early
breeding material of conventional breeding programmes. The selected breeding
material must subsequently be rigorously tested on organically managed fields starting
from the first yield trials at the latest. The project results were communicated to
farmers and advisors during field days and excursions. They will be applied in the
breeding of new cultivars
Extra cardiac findings by 64-multidetector computed tomography in patients with symptomatic atrial fibrillation prior to pulmonal vein isolation
The aim of this study was to investigate the prevalence of extracardiac findings diagnosed by 64-multidetector computed tomography (MDCT) examinations prior to circumferential pulmonary vein (PV) ablation of atrial fibrillation (AF). A total of 158 patients (median age, 60.5 years; male 68%) underwent 64-MDCT of the chest and upper abdomen to characterize left atrial and PV anatomy prior to AF ablation. MDCT images were evaluated by a thoracic radiologist and a cardiologist. For additional scan interpretation, bone, lung, and soft tissue window settings were used. CT scans with extra-cardiac abnormalities categorized for the anatomic distribution and divided into two groups: Group 1—exhibiting clinically significant or potentially significant findings, and Group 2—patients with clinically non-significant findings. Extracardiac findings (n = 198) were observed in 113/158 (72%) patients. At least one significant finding was noted in 49/158 patients (31%). Group 1 abnormalities, such as malignancies or pneumonias, were found in 85/198 findings (43%). Group 2 findings, for example mild degenerative spine disease or pleural thickening, were observed in 113/198 findings (72%). 74/198 Extracardiac findings were located in the lung (37%), 35/198 in the mediastinum (18%), 8/198 into the liver (4%) and 81/198 were in other organs (41). There is an appreciable prevalence of prior undiagnosed extracardiac findings detected in patients with AF prior to PV-Isolation by MDCT. Clinically significant or potentially significant findings can be expected in ~40% of patients who undergo cardiac MDCT. Interdisciplinary trained personnel is required to identify and interpret both cardiac and extra cardiac findings
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