166 research outputs found
Microstructural features of chromitites and ultramafic rocks of the Almaz-Zhemchuzhina deposit (Kempirsai massif, Kazakhstan) according to electron backscatter diffraction (EBSD) studies
Microstructural features of the main rock-forming minerals of host ultramafic rocks (olivine, orthopyroxene) and chrome spinel from ores of the Almaz-Zhemchuzhina deposit were studied using the electron backscatter diffraction method. For ultramafic rocks, statistical diagrams of the crystallographic orientation of olivine and orthopyroxene were obtained, indicating the formation of a mineral association in conditions of high-temperature subsolidus plastic flow in the upper mantle. The main mechanisms were translation gliding and syntectonic recrystallization. Olivine deformation occurred predominantly along the (010)[100] and (001)[100] systems. The textural and structural features of chromitites reflect plastic flow processes, most pronounced in lenticular-banded ores. Microstructure maps in inverse pole figure encoding show differences in the grain size composition of the ores: areas consisting of disseminated chromitites are characterized by a finer-grained structure compared to lens-shaped segregations of a massive structure. Analysis of microstructure maps shows that during the transition from disseminated to massive ores, there is a widespread development of recrystallization, adaptation of neighbouring grains to each other, resulting in homogenization of crystallographic orientation in aggregates. The data obtained develop ideas about the rheomorphic nature of chromitite segregations in ophiolite dunites. It is assumed that the coarsening of the structure of massive chromitites is critically associated with an increase in the concentration of ore grains during solid-phase segregation within a plastic flow, when individual chrome spinel grains, initially separated by silicate material, begin to come into direct contact with each other
Cauchy's infinitesimals, his sum theorem, and foundational paradigms
Cauchy's sum theorem is a prototype of what is today a basic result on the
convergence of a series of functions in undergraduate analysis. We seek to
interpret Cauchy's proof, and discuss the related epistemological questions
involved in comparing distinct interpretive paradigms. Cauchy's proof is often
interpreted in the modern framework of a Weierstrassian paradigm. We analyze
Cauchy's proof closely and show that it finds closer proxies in a different
modern framework.
Keywords: Cauchy's infinitesimal; sum theorem; quantifier alternation;
uniform convergence; foundational paradigms.Comment: 42 pages; to appear in Foundations of Scienc
ЧУТЛИВІСТЬ МІКРООРГАНІЗМІВ, ВИДІЛЕНИХ З ПАТОЛОГІЧНОГО МАТЕРІАЛУ, ДО АНТИМІКРОБНИХ ПРЕПАРАТІВ
Excessive and uncontrolled use of antibiotics commonly results in the emergence of antimicrobial resistance (AMR). Therefore, the main aim of these studies was to determine the antibiotic susceptibility of microorganisms isolated from the pathological material.
The article describes the susceptibility of isolated strains to the following antibiotics: ampicillin, amoxicillin, oxacillin, ofloxacin, streptomycin, cefazolin, gentamicin, amikacin, amoxiclav, erythromycin, enrofloxacin, lincomycin, tetracycline, doxycycline, vancomycin, rifampicin, ciprofloxacin, norfloxacin, tylosin, nitrofurantoin, polymyxin B.
During the study of six Escherichia coli and three Salmonella enteritidis strains, it was ascertained that they demonstrated different susceptibility to the studied antibiotics, in particular, only two E. coli isolates, which is 33,3 %, were resistant to streptomycin, 50 % of the isolated strains were susceptible.
When determining the susceptibility, it was established that all isolated E. coli isolates were resistant to cefazolin, vancomycin, oxacillin, and 83,3 % were resistant to amoxicillin, ampicillin, vancomycin, amoxiclav, rifampicin.
33,3 % of Salmonella enteritidis isolates were moderately susceptible to streptomycin, amoxicillin, and ampicillin, and 66,7 % were sensitive to ciprofloxacin, norfloxacin, and enrofloxacin.
All isolated S. enteritidis strains were found to be resistant to cefazolin, tylosin, vancomycin, oxacillin, lincomycin, and erythromycin, 100 % susceptible to ciprofloxacin, amikacin, and ofloxacin and 68,7 % moderately susceptible to amoxicillin and gentamicin.Надмірне та безконтрольне використання антибіотиків часто приводить до виникнення антибіотикорезистентності. Тому основна мета цих досліджень полягала у визначенні чутливості до антибіотиків мікроорганізмів, виділених з патматеріалу.
У статті наведене визначення чутливості виділених штамів до таких антибіотиків: ампіциліну, амоксициліну, оксациліну, офлоксацину, стрептоміцину, цефазоліну, гентаміцину, амікацину, амоксиклаву, еритроміцину, енрофлоксацину, лінкоміцину, тетрацикліну, доксицикліну, ванкоміцину, рифампіцину, ципрофлоксацину, норфлоксацину, тилозину, нітрофурантоїну, поліміксину В.
При дослідженні шести щтамів ‒ Esсherichia coli та трьох Salmonella enteritidis, встановлено, що вони проявляли різну чутливість до досліджуваних антибіотиків, зокрема резистентними до стрептоміцину виявились лише два ізоляти E. coli, що складає 33,3 %, чутливими було 50 % виділених штамів.
При визначенні чутливості встановлено, що всі виділені ізоляти E. coli були стійкими до цефазоліну, ванкоміцину, оксациліну, а 83,3 % стійкими до амоксациліну, ампіциліну, ванкоміцину, амоксиклаву, рифампіцину. 33,3 % виділених ізолятів S. enteritidis були помірно-чутливими до стрептоміцину, амоксациліну, ампіциліну, а 66,7 % ‒ чутливими до ципрофлоксацину, норфлоксацину та енрофлоксацину.
Встановлено, що всі виділені штами S. enteritidis були стійкими до цефазоліну, тилозину, ванкоміцину, оксациліну, лінкоміцину та еритроміцину, 100 % чутливими до ципрофлоксацину, амікацину та офлоксацину та 68,7 % помірно-чутливими до амоксациліну та гентаміцину
Physics of B_c mesons
In the framework of potential models for heavy quarkonium the mass spectrum
for the system () is considered. Spin-dependent splittings, taking
into account a change of a constant for effective coulomb interaction between
the quarks, and widths of radiative transitions between the () levels
are calculated. In the framework of QCD sum rules, masses of the lightest
vector and pseudoscalar states are estimated, scaling relation
for leptonic constants of heavy quarkonia is derived, and the leptonic constant
is evaluated. The decays are considered in the framework of
both the potential models and the QCD sum rules, where the significance of
Coulomb-like corrections is shown. The relations, following from the
approximate spin symmetry for the heavy quarks in the heavy quarkonium, are
analysed for the form factors of the semileptonic weak exclusive decays of
. The lifetime is evaluated with the account of the corrections to
the spectator mechanism of the decay, because of the quark binding into the
meson. The total and differential cross sections of the production in
different interactions are calculated. The analytic expressions for the
fragmentational production cross sections of are derived. The possibility
of the practical search in the current and future experiments at
electron-positron and hadron colliders is analysed.Comment: 81 page, latex, ihep.sty is required and attached in the end of the
file after \end{document}, figures are not availabl
Attacks based on malicious perturbations on image processing systems and defense methods against them
Systems implementing artificial intelligence technologies have become widespread due to their effectiveness in solving various applied tasks including computer vision. Image processing through neural networks is also used in securitycritical systems. At the same time, the use of artificial intelligence is associated with characteristic threats including disruption of machine learning models. The phenomenon of triggering an incorrect neural network response by introducing perturbations that are visually imperceptible to a person was first described and attracted the attention of researchers in 2013. Methods of attacks on neural networks based on malicious perturbations have been continuously improved, ways of disrupting the operation of neural networks in processing various types of data and tasks of the target model have been proposed. The threat of disrupting the functioning of neural networks through these attacks has become a significant problem for systems implementing artificial intelligence technologies. Thus, research in the field of countering attacks based on malicious perturbations is very relevant. This article describes current attacks, provides an overview and comparative analysis of such attacks on image processing systems based on artificial intelligence. Approaches to the classification of attacks based on malicious perturbations are formulated. Defense methods against such attacks are considered, their shortcomings are revealed. The limitations of the applied defense methods that reduce the effectiveness of counteraction to attacks are shown. Approaches and practical measures to detect and eliminate harmful disturbances are proposed
Low-Temperature Polymorphic Phase Transition in a Crystalline Tripeptide L-Ala-L-Pro-Gly·H2O Revealed by Adiabatic Calorimetry
We demonstrate application of precise adiabatic vacuum calorimetry to observation of phase transition in the tripeptide l-alanyl-l-prolyl-glycine monohydrate (APG) from 6 to 320 K and report the standard thermodynamic properties of the tripeptide in the entire range. Thus, the heat capacity of APG was measured by adiabatic vacuum calorimetry in the above temperature range. The tripeptide exhibits a reversible first-order solid-to-solid phase transition characterized by strong thermal hysteresis. We report the standard thermodynamic characteristics of this transition and show that differential scanning calorimetry can reliably characterize the observed phase transition with <5 mg of the sample. Additionally, the standard entropy of formation from the elemental substances and the standard entropy of hypothetical reaction of synthesis from the amino acids at 298.15 K were calculated for the studied tripeptide.National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB-003151)National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB-001960)National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB-002026
Corrigendum to "European contribution to the study of ROS:A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)" [Redox Biol. 13 (2017) 94-162]
The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed
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
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