1,201 research outputs found
Theoretical flow regime diagrams for the AGCE
The major criterion for the design of the Atmospheric General Circulation Experiment is that it be possible to realize strong baroclinic instability in the apparatus. A spherical annulus configuration which allows only steady basic state flows was chosen for the first set of stability analyses. Baroclinic instability was found for this configuration and few results suggest a regime diagram very different from the cylindrical annulus regime diagram
Optimization of Far-Field Antenna Range
Measurements of test antennas are performed on antenna ranges. The operated microwave far-field outdoor range was built-up in 1970’s and therefore it was not appropriate for the today measurements. Thus, it was decided to perform the complete reconstruction and testing. Some results of new ample measurement campaign are just given. The optimization of antenna range using merely measurement is very inefficient, and therefore that is done by numerical simulations. Consequently the paper surveys briefly electromagnetic wave propagation over irregular terrain. The physical optics approximation of vector problem was chosen. That allows the comparison of selected numerical simulations and measurements for the reconstructed far-field range. A possibility of antenna range optimizing by using numerical simulation considering various constraints is verified
Combined intervention with pioglitazone and n-3 fatty acids in metformin-treated type 2 diabetic patients: improvement of lipid metabolism
Background: The marine n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exert numerous beneficial effects on health, but their potency to improve treatment of type 2 diabetic (T2D) patients remains poorly characterized. We aimed to evaluate the effect of a combination intervention using EPA?+?DHA and the insulin-sensitizing drug pioglitazone in overweight/obese T2D patients already treated with metformin.Methods: In a parallel-group, four-arm, randomized trial, 69 patients (66 % men) were assigned to 24-week-intervention using: (i) corn oil (5 g/day; Placebo), (ii) pioglitazone (15 mg/day; Pio), (iii) EPA?+?DHA concentrate (5 g/day, containing ~2.8 g EPA?+?DHA; Omega-3), or (iv) pioglitazone and EPA?+?DHA concentrate (Pio& Omega-3). Data from 60 patients were used for the final evaluation. At baseline and after intervention, various metabolic markers, adiponectin and cytokines were evaluated in serum using standard procedures, EPA?+?DHA content in serum phospholipids was evaluated using shotgun lipidomics and mass spectrometry, and hyperinsulinemic-euglycemic clamp and meal test were also performed. Indirect calorimetry was conducted after the intervention. Primary endpoints were changes from baseline in insulin sensitivity evaluated using hyperinsulinemic-euglycemic clamp and in serum triacylglycerol concentrations in fasting state. Secondary endpoints included changes in fasting glycemia and glycated hemoglobin (HbA1c), changes in postprandial glucose, free fatty acid and triacylglycerol concentrations, metabolic flexibility assessed by indirect calorimetry, and inflammatory markers.Results: Omega-3 and Pio& Omega-3 increased EPA?+?DHA content in serum phospholipids. Pio and Pio& Omega-3 increased body weight and adiponectin levels. Both fasting glycemia and HbA1c were increased by Omega-3, but were unchanged by Pio& Omega-3. Insulin sensitivity was not affected by Omega-3, while it was improved by Pio& Omega-3. Fasting triacylglycerol concentrations and inflammatory markers were not significantly affected by any of the interventions. Lipid metabolism in the meal test and metabolic flexibility were additively improved by Pio& Omega-3.Conclusion: Besides preventing a modest negative effect of n-3 fatty acids on glycemic control, the combination of pioglitazone and EPA?+?DHA can be used to improve lipid metabolism in T2D patients on stable metformin therapy.Trial registration: EudraCT number 2009-011106-42.<br/
Monte-Carlo Simulations of Radiation-Induced Activation in a Fast-Neutron and Gamma- Based Cargo Inspection System
An air cargo inspection system combining two nuclear reaction based
techniques, namely Fast-Neutron Resonance Radiography and Dual-Discrete-Energy
Gamma Radiography is currently being developed. This system is expected to
allow detection of standard and improvised explosives as well as special
nuclear materials. An important aspect for the applicability of nuclear
techniques in an airport inspection facility is the inventory and lifetimes of
radioactive isotopes produced by the neutron and gamma radiation inside the
cargo, as well as the dose delivered by these isotopes to people in contact
with the cargo during and following the interrogation procedure. Using MCNPX
and CINDER90 we have calculated the activation levels for several typical
inspection scenarios. One example is the activation of various metal samples
embedded in a cotton-filled container. To validate the simulation results, a
benchmark experiment was performed, in which metal samples were activated by
fast-neutrons in a water-filled glass jar. The induced activity was determined
by analyzing the gamma spectra. Based on the calculated radioactive inventory
in the container, the dose levels due to the induced gamma radiation were
calculated at several distances from the container and in relevant time windows
after the irradiation, in order to evaluate the radiation exposure of the cargo
handling staff, air crew and passengers during flight. The possibility of
remanent long-lived radioactive inventory after cargo is delivered to the
client is also of concern and was evaluated.Comment: Proceedings of FNDA 201
Recommendations for MYRRHA relevant cross section data to the JEFF project
Within the framework of Work Package 10 of the EC FP7 CHANDA project, nuclear data of importance for the operation of MYRRHA, a lead-bismuth cooled accelerator driven reactor under development at SCK•CEN (BE), were studied. Based on data in the main nuclear data libraries, i.e. JEFF, JENDL, ENDF/B and BROND, and in the TENDL and CIELO libraries and on experimental data reported in the literature, recommendations to the JEFF project were made for several nuclides of interest to the MYRRHA reactor.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard
Status of evaluated data files for 238U in the resonance region
Experimental data and evaluated data libraries related to neutron induced reaction cross sections for 238U in the resonance region are reviewed. Based on this review a set of test files is produced to study systematic effects such as the impact of the upper boundary of the resolved resonance region (RRR) and the representation of the infinite diluted capture and in-elastic cross section in the unresolved resonance region (URR). A set of Benchmark experiments was selected and used to verify the test files. Based on these studies recommendations to perform a new evaluation have been defined.
This report has been prepared in support to the CIELO (Collaborative International Evaluated Library Organisation) project. The objective of this project is the creation of a world-wide recognised nuclear data file with a focus on six nuclides, i.e. 1H, 16O, 56Fe, 235U, 238U and 239Pu. Within the CIELO project, the Joint Research Centre (JRC) at Geel (B) is in charge of the production of an evaluated cross section data file for neutron induced reaction of 238U in the resonance region.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard
Effect of recent R_p and R_n measurements on extended Gari-Krumpelmann model fits to nucleon electromagnetic form factors
The Gari-Krumpelmann (GK) models of nucleon electromagnetic form factors, in
which the rho, omega, and phi vector meson pole contributions evolve at high
momentum transfer to conform to the predictions of perturbative QCD (pQCD), was
recently extended to include the width of the rho meson by substituting the
result of dispersion relations for the pole and the addition of rho' (1450)
isovector vector meson pole. This extended model was shown to produce a good
overall fit to all the available nucleon electromagnetic form factor (emff)
data. Since then new polarization data shows that the electric to magnetic
ratios R_p and R_n obtained are not consistent with the older G_{Ep} and G_{En}
data in their range of momentum transfer. The model is further extended to
include the omega' (1419) isoscalar vector meson pole. It is found that while
this GKex cannot simultaneously fit the new R_p and the old G_{En} data, it can
fit the new R_p and R_n well simultaneously. An excellent fit to all the
remaining data is obtained when the inconsistent G_{Ep} and G_{En} is omitted.
The model predictions are shown up to momentum transfer squared, Q^2, of 8
GeV^2/c^2.Comment: 14 pages, 8 figures, using RevTeX4; email correspondence to
[email protected] ; minor typos corrected, figures added, conclusions
extende
NDEC: A NEA platform for nuclear data testing, verification and benchmarking
The selection, testing, verification and benchmarking of evaluated nuclear data consists, in practice, in putting an evaluated file through a number of checking steps where different computational codes verify that the file and the data it contains complies with different requirements. These requirements range from format compliance to good performance in application cases, while at the same time physical constraints and the agreement with experimental data are verified. At NEA, the NDEC (Nuclear Data Evaluation Cycle) platform aims at providing, in a user friendly interface, a thorough diagnose of the quality of a submitted evaluated nuclear data file. Such diagnose is based on the results of different computational codes and routines which carry out the mentioned verifications, tests and checks. NDEC also searches synergies with other existing NEA tools and databases, such as JANIS, DICE or NDaST, including them into its working scheme. Hence, this paper presents NDEC, its current development status and its usage in the JEFF nuclear data project
Dysregulation of epicardial adipose tissue in cachexia due to heart failure. the role of natriuretic peptides and cardiolipin
Background: Cachexia worsens long-term prognosis of patients with heart failure (HF). Effective treatment of cachexia is missing. We seek to characterize mechanisms of cachexia in adipose tissue, which could serve as novel targets for the treatment. Methods: The study was conducted in advanced HF patients (n = 52; 83% male patients) undergoing heart transplantation. Patients with ≥7.5% non-intentional body weight (BW) loss during the last 6 months were rated cachectic. Clinical characteristics and circulating markers were compared between cachectic (n = 17) and the remaining, BW-stable patients. In epicardial adipose tissue (EAT), expression of selected genes was evaluated, and a combined metabolomic/lipidomic analysis was performed to assess (i) the role of adipose tissue metabolism in the development of cachexia and (ii) potential impact of cachexia-associated changes on EAT-myocardium environment. Results: Cachectic vs. BW-stable patients had higher plasma levels of natriuretic peptide B (BNP; 2007 ± 1229 vs. 1411 ± 1272 pg/mL; P = 0.010) and lower EAT thickness (2.1 ± 0.8 vs. 2.9 ± 1.4 mm; P = 0.010), and they were treated with ~2.5-fold lower dose of both β-blockers and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (ACE/ARB-inhibitors). The overall pattern of EAT gene expression suggested simultaneous activation of lipolysis and lipogenesis in cachexia. Lower ratio between expression levels of natriuretic peptide receptors C and A was observed in cachectic vs. BW-stable patients (0.47 vs. 1.30), supporting activation of EAT lipolysis by natriuretic peptides. Fundamental differences in metabolome/lipidome between BW-stable and cachectic patients were found. Mitochondrial phospholipid cardiolipin (CL), specifically the least abundant CL 70:6 species (containing C16:1, C18:1, and C18:2 acyls), was the most discriminating analyte (partial least squares discriminant analysis; variable importance in projection score = 4). Its EAT levels were higher in cachectic as compared with BW-stable patients and correlated with the degree of BW loss during the last 6 months (r = −0.94; P = 0.036). Conclusions: Our results suggest that (i) BNP signalling contributes to changes in EAT metabolism in cardiac cachexia and (ii) maintenance of stable BW and ‘healthy’ EAT-myocardium microenvironment depends on the ability to tolerate higher doses of both ACE/ARB inhibitors and β-adrenergic blockers. In line with preclinical studies, we show for the first time in humans the association of cachexia with increased adipose tissue levels of CL. Specifically, CL 70:6 could precipitate wasting of adipose tissue, and thus, it could represent a therapeutic target to ameliorate cachexia
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