535 research outputs found
Radio Telescope Focal Container for the Russian VLBI Network of New Generation
This article considers the development of the structure of receivers for Russian radio telescopes. The development of these radio telescopes is undertaken within the project for creating a Russian small-antenna-based radio interferometer of new generation. It is shown that for small antennas (10. 12 meter) the principal unit, which provides the best SNR, is the so-called focal container placed at primary focus. It includes the primary feed, HEMT LNA, and cryogenic cooling system down to 20. K. A new multi-band feed based on traveling wave resonators is used. It has small dimensions, low weight, and allows working with circular polarizations. Thus it can be placed into focal container and cooled with the LNA. A sketch of the focal container, with traveling-wave-resonator feed, and calculations of the expected parameters of the multi-band receiver are presented
Effect of multistage high temperature thermomechanical treatment on the microstructure and mechanical properties of austenitic reactor steel
The deformation microstructures formed by novel multistage high-temperature thermomechanical treatment (HTMT) and their effect on the mechanical properties of austenitic reactor steel are investigated. It is shown that HTMT with plastic deformation at the temperature decreasing in each stage (1100, 900, and 600 C with a total strain degree of e = 2) is an effective method for refining the grain structure and increasing the strength of the reactor steel. The structural features of grains, grain boundaries and defective substructure of the steel are studied in two sections (in planes perpendicular to the transverse direction and perpendicular to the normal direction) by Scanning Electron Microscopy with Electron Back-Scatter Diffraction (SEM EBSD) and Transmission Electron Microscopy (TEM). After the multistage HTMT, a fragmented structure is formed with grains elongated along the rolling direction and flattened in the rolling plane. The average grain size decreases from 19.3 m (for the state after solution treatment) to 1.8 m. A high density of low-angle boundaries (up to 80%) is found inside deformed grains. An additional cold deformation (e = 0.3) after the multistage HTMT promotes mechanical twinning within fragmented grains and subgrains. The resulting structural states provide high strength properties of steel: the yield strength increases up to 910 MPa (at 20 C) and up to 580 MPa (at 650 C), which is 4.6 and 6.1 times higher than that in the state after solution treatment (ST), respectively. The formation of deformed substructure and the influence of dynamic strain aging at an elevated tensile temperature on the mechanical properties of the steel are discussed. Based on the results obtained, the multistage HTMT used in this study can be applied for increasing the strength of austenitic steels
Radiopharmaceuticals for SPECT Cancer Detection
The purpose of the study was to assess the efficacy of single photon emission computed tomography (SPECT) with {199}Tl and {99}mTc-MIBI in the detection of breast, laryngeal and hypopharyngeal cancers. A total of 220 patients were included into the study: 120 patients with breast lesions (100 patients with breast cancer and 20 patients with benign breast tumors) and 100 patients with laryngeal/hypopharyngeal diseases (80 patients with laryngeal/hypopharyngeal cancer and 20 patients with benign laryngeal/hypopharyngeal lesions). No abnormal {199}Tl uptake was seen in all patients with benign breast and laryngeal lesions, indicating a 100% specificity of {199}Tl SPECT. In the breast cancer patients, the increased {199}Tl uptake in the breast was visualized in 94.8% patients, {99m}Tc-MIBI-in 93.4% patients. The increased {199}Tl uptake in axillary lymph nodes was detected in 60% patients, and {99m}Tc-MIBI-in 93.1% patients. In patients with laryngeal/hypopharyngeal cancer, the sensitivity of SPECT with {199}Tl and {99m}Tc-MIBI was 95%. The {199}Tl SPECT sensitivity in identification of regional lymph node metastases in the patients with laryngeal/hypopharyngeal cancer was 75% and the {99m}Tc-MIBI SPECT sensitivity was 17%. The data obtained showed that SPECT with {199}Tl and {99m}Tc-MIBI can be used as one of the additional imaging methods in detection of tumors
Factors affecting eluation characteristics of sorption generators of technetium-99m
The influence of the adsorbed mass of molybdenum on the width of eluation profiles of generators and the patterns of molybdenum distribution in the amount of chromatographic columns by scanning them on the germanium-gallium detector using collimating device are studied. The boundary conditions under which the maximum value of {99m}Tc yield from generators Y[e]=1 are defined. After scanning the columns, it was found out that the degree of filling the columns with molybdenum Q and the value of its maximum adsorption depend naturally on the total weight of the adsorbed mass. In order to achieve the condition Y[e]=1 the value of Q should be at least 85%
Intravenously Injected Amyloid-ÎČ Peptide With Isomerized Asp7 and Phosphorylated Ser8 Residues Inhibits Cerebral ÎČ-Amyloidosis in AÎČPP/PS1 Transgenic Mice Model of Alzheimerâs Disease
Cerebral ÎČ-amyloidosis, an accumulation in the patientâs brain of aggregated amyloid-ÎČ (AÎČ) peptides abnormally saturated by divalent biometal ions, is one of the hallmarks of Alzheimerâs disease (AD). Earlier, we found that exogenously administrated synthetic AÎČ with isomerized Asp7 (isoD7-AÎČ) induces AÎČ fibrillar aggregation in the transgenic mice model of AD. IsoD7-AÎČ molecules have been implied to act as seeds enforcing endogenous AÎČ to undergo pathological aggregation through zinc-mediated interactions. On the basis of our findings on zinc-induced oligomerization of the metal-binding domain of various AÎČ species, we hypothesize that upon phosphorylation of Ser8, isoD7-AÎČ loses its ability to form zinc-bound oligomeric seeds. In this work, we found that (i) in vitro isoD7-AÎČ with phosphorylated Ser8 (isoD7-pS8-AÎČ) is less prone to spontaneous and zinc-induced aggregation in comparison with isoD7-AÎČ and intact AÎČ as shown by thioflavin T fluorimetry and dynamic light scattering data, and (ii) intravenous injections of isoD7-pS8-AÎČ significantly slow down the progression of institutional ÎČ-amyloidosis in AÎČPP/PS1 transgenic mice as shown by the reduction of the congophilic amyloid plaquesâ number in the hippocampus. The results support the role of the zinc-mediated oligomerization of AÎČ species in the modulation of cerebral ÎČ-amyloidosis and demonstrate that isoD7-pS8-AÎČ can serve as a potential molecular tool to block the aggregation of endogenous AÎČ in AD
Phosphorylation of the Amyloid-Beta Peptide Inhibits Zinc-Dependent Aggregation, Prevents Na,K-ATPase Inhibition, and Reduces Cerebral Plaque Deposition
The triggers of late-onset sporadic Alzheimerâs disease (AD) are still poorly understood. Impairment of protein phosphorylation with age is well-known; however, the role of the phosphorylation in ÎČ-amyloid peptide (AÎČ) is not studied sufficiently. Zinc-induced oligomerization of AÎČ represents a potential seeding mechanism for the formation of neurotoxic AÎČ oligomers and aggregates. Phosphorylation of AÎČ by Ser8 (pS8-AÎČ), localized inside the zinc-binding domain of the peptide, may significantly alter its zinc-induced oligomerization. Indeed, using dynamic light scattering, we have shown that phosphorylation by Ser8 dramatically reduces zinc-induced aggregation of AÎČ, and moreover pS8-AÎČ suppresses zinc-driven aggregation of non-modified AÎČ in an equimolar mixture. We have further analyzed the effect of pS8-AÎČ on the progression of cerebral amyloidosis with serial retro-orbital injections of the peptide in APPSwe/PSEN1dE9 murine model of AD, followed by histological analysis of amyloid burden in hippocampus. Unlike the non-modified AÎČ that has no influence on the amyloidosis progression in murine models of AD, pS8-AÎČ injections reduced the number of amyloid plaques in the hippocampus of mice by one-third. Recently shown inhibition of Na+,K+-ATPase activity by AÎČ, which is thought to be a major contributor to neuronal dysfunction in AD, is completely reversed by phosphorylation of the peptide. Thus, several AD-associated pathogenic properties of AÎČ are neutralized by its phosphorylation
Multidifferential study of identified charged hadron distributions in -tagged jets in proton-proton collisions at 13 TeV
Jet fragmentation functions are measured for the first time in proton-proton
collisions for charged pions, kaons, and protons within jets recoiling against
a boson. The charged-hadron distributions are studied longitudinally and
transversely to the jet direction for jets with transverse momentum 20 GeV and in the pseudorapidity range . The
data sample was collected with the LHCb experiment at a center-of-mass energy
of 13 TeV, corresponding to an integrated luminosity of 1.64 fb. Triple
differential distributions as a function of the hadron longitudinal momentum
fraction, hadron transverse momentum, and jet transverse momentum are also
measured for the first time. This helps constrain transverse-momentum-dependent
fragmentation functions. Differences in the shapes and magnitudes of the
measured distributions for the different hadron species provide insights into
the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb
public pages
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
Measurement of the ratios of branching fractions and
The ratios of branching fractions
and are measured, assuming isospin symmetry, using a
sample of proton-proton collision data corresponding to 3.0 fb of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The
tau lepton is identified in the decay mode
. The measured values are
and
, where the first uncertainty is
statistical and the second is systematic. The correlation between these
measurements is . Results are consistent with the current average
of these quantities and are at a combined 1.9 standard deviations from the
predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb
public pages
Task Scheduling in Desktop Grids: Open Problems
We survey the areas of Desktop Grid task scheduling that seem to be insufficiently studied so far and are promising for efficiency, reliability, and quality of Desktop Grid computing. These topics include optimal task grouping, âneedle in a haystackâ paradigm, game-theoretical scheduling, domain-imposed approaches, special optimization of the final stage of the batch computation, and Enterprise Desktop Grids
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