207 research outputs found
Patient Specific Diagnostics for cardiovascular diseases based on diagnostic imaging: an application to the aneurism of the ascending aorta
In the framework of a collaboration between clinicians and engineers (namely, the Department of Radiology of the Brotzu Hospital in Cagliari and the group of experimental hydraulics at DICAAR - University of Cagliari), methodologies for the application of the in vitro study of the cardiovascular fluid mechanics to the support of the physical interpretation of the diagnostic imaging data are being tested. To this aim, we set up a mock-loop able to reproduce the physiologic pulsatile flow and designed to host a replica of aortic root made of transparent silicon rubber. Then, we developed a procedure to obtain a transparent and compliant replica of a patient specific ascending aorta from diagnostic images. The patient specific aorta model can be inserted in the mock-loop to study the fluid dynamics by means of particle image velocimetry techniques. We compared the flow in three cases, corresponding to physiological conditions, mild and severe aortic root dilation, observing significant differences in the redirection of the transvalvular jet and vortex evolution in the aortic flow. The observed fluid dynamics differences may have relevant implications on the thromboembolism and vascular tissue damage potential
Reading a GEM with a VLSI pixel ASIC used as a direct charge collecting anode
In MicroPattern Gas Detectors (MPGD) when the pixel size is below 100 micron
and the number of pixels is large (above 1000) it is virtually impossible to
use the conventional PCB read-out approach to bring the signal charge from the
individual pixel to the external electronics chain. For this reason a custom
CMOS array of 2101 active pixels with 80 micron pitch, directly used as the
charge collecting anode of a GEM amplifying structure, has been developed and
built. Each charge collecting pad, hexagonally shaped, realized using the top
metal layer of a deep submicron VLSI technology is individually connected to a
full electronics chain (pre-amplifier, shaping-amplifier, sample and hold,
multiplexer) which is built immediately below it by using the remaining five
active layers. The GEM and the drift electrode window are assembled directly
over the chip so the ASIC itself becomes the pixelized anode of a MicroPattern
Gas Detector. With this approach, for the first time, gas detectors have
reached the level of integration and resolution typical of solid state pixel
detectors. Results from the first tests of this new read-out concept are
presented. An Astronomical X-Ray Polarimetry application is also discussed.Comment: 11 pages, 14 figures, presented at the Xth Vienna Conference on
Instrumentation (Vienna, February 16-21 2004). For a higher resolution paper
contact [email protected]
Effect of restriction vegan diet's on muscle mass, oxidative status, and myocytes differentiation: A pilot study
This study was conceived to evaluate the effects of three different diets on body composition, metabolic parameters and serum oxidative status. We enrolled three groups of healthy men (omnivores, vegetarians and vegans) with similar age, weight and BMI and we observed a significant decrease in muscle mass index and lean body mass in vegan compared to vegetarian and omnivore groups, and higher serum homocysteine levels in vegetarians and vegans compared to omnivores. We studied whether serum from omnivore, vegetarian and vegan subjects affected oxidative stress, growth and differentiation of both cardiomyoblast cell line H9c2 and H-H9c2 (H9c2 treated with H2 O2 to induce oxidative damage). We demonstrated that vegan sera treatment of both H9c2 and H-H9c2 cells induced an increase of TBARS values and cell death and a decrease of free NO2- compared to vegetarian and omnivorous sera. Afterwards, we investigated the protective effects of vegan, vegetarian and omnivore sera on the morphological changes induced by H2 O2 in H9c2 cell line. We showed that the omnivorous sera had major antioxidant and differentiation properties compared to vegetarian and vegan sera. Finally, we evaluated the influence of the three different groups of sera on MAPKs pathway and our data suggested that ERK expression increased in H-H9c2 cells treated with vegetarian and vegan sera and could promote cell death. The results obtained in this study demonstrated that restrictive vegan diet could not prevent the onset of metabolic and cardiovascular diseases nor protect by oxidative damage. This article is protected by copyright. All rights reserved
An X-ray polarimeter for hard X-ray optics
Development of multi-layer optics makes feasible the use of X-ray telescope
at energy up to 60-80 keV: in this paper we discuss the extension of
photoelectric polarimeter based on Micro Pattern Gas Chamber to high energy
X-rays. We calculated the sensitivity with Neon and Argon based mixtures at
high pressure with thick absorption gap: placing the MPGC at focus of a next
generation multi-layer optics, galatic and extragalactic X-ray polarimetry can
be done up till 30 keV.Comment: 12 pages, 7 figure
Congenital hypothyroidism due to a new deletion in the sodium/iodide symporter protein.
OBJECTIVE:
Iodide transport defect (ITD) is a rare disorder characterised by an inability of the thyroid to maintain an iodide gradient across the basolateral membrane of thyroid follicular cells, that often results in congenital hypothyroidism. When present the defect is also found in the salivary glands and gastric mucosa and it has been shown to arise from abnormalities of the sodium/iodide symporter (NIS).
PATIENT:
We describe a woman with hypothyroidism identified at the 3rd month of life. The diagnosis of ITD was suspected because of nodular goitre, and little if any iodide uptake by the thyroid and salivary glands. Treatment with iodide partially corrected the hypothyroidism; however, long-term substitution therapy with L-thyroxine was started.
MEASUREMENTS:
Thyroid radioiodide uptake was only 1.4% and 0.3% at 1 and 24 h after the administration of recombinant human TSH. The saliva to plasma I- ratio was 1.1 indicating that the inability of the thyroid gland to concentrate I- was also present in the salivary glands.
RESULTS:
Analysis of the patient's NIS gene revealed a 15 nucleotide (nt) deletion of the coding sequence (nt 1314 through nt 1328) and the insertion of 15 nt duplicating the first 15 nt of the adjacent intron. The patient was homozygous for this insertion/deletion, while both consanguineous parents were heterozygous. This deletion predicts the production of a protein lacking the five terminal amino acids of exon XI (439-443) which are located in the 6th intracellular loop. COS-7 cells transfected with a vector expressing the mutant del-(439-443) NIS failed to concentrate iodide, suggesting that the mutation was the direct cause of the ITD in this patient.
CONCLUSION:
In conclusion we describe the first Italian case of congenital hypothyroidism due to a new deletion in the NIS gene
Opening a New Window to Fundamental Physics and Astrophysics: X-ray Polarimetry
An extensive theoretical literature predicts that X-ray Polarimetry can
directly determine relevant physical and geometrical parameters of
astrophysical sources, and discriminate between models further than allowed by
spectral and timing data only. X-ray Polarimetry can also provide tests of
Fundamental Physics. A high sensitivity polarimeter in the focal plane of a New
Generation X-ray telescope could open this new window in the High Energy Sky.Comment: 8 pages 1 table 14 figure
Gas Pixel Detectors for X-ray Polarimetry applications
We discuss a new class of Micro Pattern Gas Detectors, the Gas Pixel Detector
(GPD), in which a complete integration between the gas amplification structure
and the read-out electronics has been reached. An Application-Specific
Integrated Circuit (ASIC) built in deep sub-micron technology has been
developed to realize a monolithic device that is, at the same time, the
pixelized charge collecting electrode and the amplifying, shaping and charge
measuring front-end electronics. The CMOS chip has the top metal layer
patterned in a matrix of 80 micron pitch hexagonal pixels, each of them
directly connected to the underneath electronics chain which has been realized
in the remaining five layers of the 0.35 micron VLSI technology. Results from
tests of a first prototype of such detector with 2k pixels and a full scale
version with 22k pixels are presented. The application of this device for
Astronomical X-Ray Polarimetry is discussed. The experimental detector response
to polarized and unpolarized X-ray radiation is shown. Results from a full
MonteCarlo simulation for two astronomical sources, the Crab Nebula and the
Hercules X1, are also reported.Comment: 16 pages, 20 figures, accepted for publication in Nuclear Instruments
and Methods in Physics Research Section
A photoelectric polarimeter for XEUS: a new window in x-ray sky
XEUS is a large area telescope aiming to rise X-ray Astronomy to the level of
Optical Astronomy in terms of collecting areas. It will be based on two
satellites, locked on a formation flight, one with the optics, one with the
focal plane. The present design of the focal plane foresees, as an auxiliary
instrument, the inclusion of a Polarimeter based on a Micropattern Chamber. We
show how such a device is capable to solve open problems on many classes of
High Energy Astrophysics objects and to use X-ray sources as a laboratory for a
substantial progress on Fundamental Physics.Comment: 12 pages, 7 figure
POLARIX: a small mission of x-ray polarimetry
X-Ray Polarimetry can be now performed by using a Micro Pattern Gas Chamber
in the focus of a telescope. It requires large area optics for most important
scientific targets. But since the technique is additive a dedicated mission
with a cluster of small telescopes can perform many important measurements and
bridge the 40 year gap between OSO-8 data and future big telescopes such as
XEUS. POLARIX has been conceived as such a pathfinder. It is a Small Satellite
based on the optics of JET-X. Two telescopes are available in flight
configuration and three more can be easily produced starting from the available
superpolished mandrels. We show the capabilities of such a cluster of
telescopes each equipped with a focal plane photoelectric polarimeter and
discuss a few alternative solutions.Comment: 9 pages, 5 figure
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