545 research outputs found
A dual output polarimeter devoted to the study of the Cosmic Microwave Background
We have developed a correlation radiometer at 33 GHz devoted to the search
for residual polarization of the Cosmic Microwave Background (CMB). The two
instruments`s outputs are linear combination of two Stokes Parameters (Q and U
or U and V). The instrument is therefore directly sensitive to the polarized
component of the radiation (respectively linear and circular). The radiometer
has a beam-width oif 7 or 14 deg, but it can be coupled to a telescope
increasing the resolution. The expected CMB polarization is at most a part per
milion. The polarimeter has been designed to be sensitive to this faint signal,
and it has been optimized to improve its long term stability, observing from
the ground. In this contribution the performances of the instrument are
presented, together with the preliminary test and observations.Comment: 12 pages, 6 figures, in print on the Proc. SPIE Conf. - August 200
TRIS II: search for CMB spectral distortions at 0.60, 0.82 and 2.5 GHz
With the TRIS experiment we have performed absolute measurements of the sky
brightness in a sky circle at at the frequencies
0.60, 0.82 and 2.5 GHz. In this paper we discuss the techniques used to
separate the different contributions to the sky emission and give an evaluation
of the absolute temperature of the Cosmic Microwave Background. For the
black-body temperature of the CMB we get: at GHz; at GHz; at
GHz. The first error bar is statistic (1) while the second
one is systematic. These results represent a significant improvement with
respect to the previous measurements. We have also set new limits to the
free-free distortions, ,
and slightly improved the Bose-Einstein upper limit, , both at 95% confidence level.Comment: accepted for publication in The Astrophysical Journa
Blue toe syndrome: A challenging diagnosis
\u201cBlue toe syndrome\u201d (BTS) refers to the acute onset of purple painful digits in the absence of evident trauma, cold-associated injury or disorders that induce generalized cyanosis. The term was used for the first time in 1976 by Komody, who underlined the vascular etiology of the disease and its possible diagnostic confirmation through angiography.[1,2] Indeed, BTS may occur from end-arterial occlusion, impaired venous outflow, and/or abnormal blood circulation. Peripheral microembolism with distal arterial occlusion is one of the most frequent underlying mechanisms of the disease and consists of disrupted material from ulcerated atheromatous plaques (atheromatous or cholesterol crystal emboli). The case described by us assumes significance because of an atypical clinical presentation of a peripheral embolism from an abdominal aortic aneurysm, hence necessitating a high index of suspicion to achieve the correct diagnosis.
TRIS I: Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82 and 2.5 GHz
At frequencies close to 1 GHz the sky diffuse radiation is a superposition of
radiation of Galactic origin, the 3 K Relic or Cosmic Microwave Background
Radiation, and the signal produced by unresolved extragalactic sources. Because
of their different origin and space distribution the relative importance of the
three components varies with frequency and depends on the direction of
observation. With the aim of disentangling the components we built TRIS, a
system of three radiometers, and studied the temperature of the sky at , and GHz using geometrically scaled antennas
with identical beams (HPBW = ). Observations
included drift scans along a circle at constant declination
which provided the dependence of the sky signal on the
Right Ascension, and absolute measurement of the sky temperature at selected
points along the same scan circle. TRIS was installed at Campo Imperatore (lat.
= N, long.= , elevation = 2000 m a.s.l.) in
Central Italy, close to the Gran Sasso Laboratory.Comment: Accepted for publication in The Astrophysical Journa
EBT2 Dosimetry of X-rays produced by the electron beam from PFMA-3, a Plasma Focus for medical applications
The electron beam emitted from the back of Plasma Focus devices is being
studied as a radiation source for IORT (IntraOperative Radiation Therapy)
applications. A Plasma Focus device is being developed to this aim, to be
utilized as an X-ray source. The electron beam is driven to impinge on 50
{\mu}m brass foil, where conversion X-rays are generated. Measurements with
gafchromic film are performed to analyse the attenuation of the X-rays beam and
to predict the dose given to the culture cell in radiobiological experiments to
follow.Comment: 10 pages, 14 figure
Search for distortions in the spectrum of the Cosmic Microwave Radiation
We present preliminary results of TRIS, an experiment dedicated to the search
of deviations from a pure planckian distribution in the spectrum of the Cosmic
Microwave Background at frequencies close to 1 GHzComment: 9 pages, in press on the Proc. of the 3rd Sakharov Conf. - Moscow
200
Benefits from using combined dynamical-statistical downscaling approaches - Lessons from a case study in the Mediterranean region
Abstract. Various downscaling techniques have been developed to bridge the scale gap between global climate models (GCMs) and finer scales required to assess hydrological impacts of climate change. Such techniques may be grouped into two downscaling approaches: the deterministic dynamical downscaling (DD) and the statistical downscaling (SD). Although SD has been traditionally seen as an alternative to DD, recent works on statistical downscaling have aimed to combine the benefits of these two approaches. The overall objective of this study is to assess whether a DD processing performed before the SD permits to obtain more suitable climate scenarios for basin scale hydrological applications starting from GCM simulations. The case study presented here focuses on the Apulia region (South East of Italy, surface area about 20 000 km2), characterised by a typical Mediterranean climate; the monthly cumulated precipitation and monthly mean of daily minimum and maximum temperature distribution were examined for the period 1953â2000. The fifth-generation ECHAM model from the Max-Planck-Institute for Meteorology was adopted as GCM. The DD was carried out with the Protheus system (ENEA), while the SD was performed through a monthly quantile-quantile correction. The SD resulted efficient in reducing the mean bias in the spatial distribution at both annual and seasonal scales, but it was not able to correct the miss-modelled non-stationary components of the GCM dynamics. The DD provided a partial correction by enhancing the spatial heterogeneity of trends and the long-term time evolution predicted by the GCM. The best results were obtained through the combination of both DD and SD approaches
Predicting future cancer burden in the United States by artificial neural networks
Aims: To capture the complex relationships between risk factors and cancer incidences in the US and predict future cancer burden. Materials & methods: Two artificial neural network (ANN) algorithms were adopted: a multilayer feed-forward network (MLFFNN) and a nonlinear autoregressive network with eXogenous inputs (NARX). Data on the incidence of the four most common tumors (breast, colorectal, lung and prostate) from 1992 to 2016 (available from National Cancer Institute online datasets) were used for training and validation, and data until 2050 were predicted. Results: The rapid decreasing trend of prostate cancer incidence started in 2010 will continue until 2018â2019; it will then slow down and reach a plateau after 2050, with several differences among ethnicities. The incidence of breast cancer will reach a plateau in 2030, whereas colorectal cancer incidence will reach a minimum value of 35 per 100,000 in 2030. As for lung cancer, the incidence will decrease from 50 per 100,000 (2017) to 31 per 100,000 in 2030 and 26 per 100,000 in 2050. Conclusion: This up-to-date prediction of cancer burden in the US could be a crucial resource for planning and evaluation of cancer-control programs
Febrile Neutropenia Duration Is Associated with the Severity of Gut Microbiota Dysbiosis in Pediatric Allogeneic Hematopoietic Stem Cell Transplantation Recipients
Febrile neutropenia (FN) is a common complication in pediatric patients receiving al-logeneic hematopoietic stem cell transplantation (HSCT). Frequently, a precise cause cannot be identified, and many factors can contribute to its genesis. Gut microbiota (GM) has been recently linked to many transplant-related complications, and may also play a role in the pathogenesis of FN. Here, we conducted a longitudinal study in pediatric patients receiving HSCT from three centers in Europe profiling their GM during the transplant course, particularly at FN onset. We found that a more stable GM configuration over time is associated with a shorter duration of fever. Moreover, patients with longer lasting fever exhibited higher pre-HSCT levels of Collinsella, Megasphaera, Prevotella and Roseburia and increased proportions of Eggerthella and Akkermansia at the engraftment. These results suggest a possible association of the GM with the genesis and course of FN. Data seem consistent with previous reports on the relationship of a so-called âhealthyâ GM and the reduction of transplant complications. To our knowledge, this is the first report in the pediatric HSCT setting. Future studies are warranted to define the underling biological mechanisms and possible clinical implications
Chemical characterization of biomass fuel particulate deposits and ashes in households of Mt. Everest region (NEPAL)
During a sampling campaign, carried out during June 2012, inside some traditional households located in four villages (Phakding, Namche, Pangboche and Tukla) of Mt. Everest region in southern part of the central Himalaya (Nepal), particulate matter (PM) depositions and ashes have been collected. Moreover, outdoor PM depositions have also been analyzed. Chemical characterization of PM depositions and ashes for major ions, organic carbon, elemental carbon (EC), metal content and PAHs (Polycyclic Aromatic Hydrocarbons) allowed identifying, as major contributes to indoor PM, the following sources: biomass burning, cooking and chimney ashes. These sources significantly affect outdoor PM depositions: in-house biomass burning is the major source for outdoor EC and K+ as well as biomass burning and cooking activities are the major sources for Polycyclic Aromatic Hydrocarbons
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