5,444 research outputs found
Mass distributions for nuclear disintegration from fission to evaporation
By a proper choice of the excitation energy per nucleon we analyze the mass
distributions of the nuclear fragmentation at various excitation energies.
Starting from low energies (between 0.1 and 1 MeV/nucleon) up to higher
energies about 12 MeV/n, we classified the mass yield characteristics for heavy
nuclei (A>200) on the basis of Statistical Multifragmentation Model. The
evaluation of fragment distribution with the excitation energy show that the
present results exhibit the same trend as the experimental ones.Comment: 5 pages, 3 figure
Effective moment of inertia for several fission reaction systems induced by nucleons, light particles and heavy ions
Compound nucleus effective moment of inertia has been calculated for several
fission reaction systems induced by nucleons, light particles, and heavy ions.
Determination of this quantity for these systems is based upon the comparison
between the experimental data of the fission fragment angular distributions as
well as the prediction of the standard saddle-point statistical model (SSPSM).
For the systems, the two cases, namely with and without neutron emission
corrections were considered. In these calculations, it is assumed that all the
neutrons are emitted before reaching the saddle point.It should be noted that
the above method for determining of the effective moment of inertia had not
been reported until now and this method is used for the first time to determine
compound nucleus effective moment of inertia. Hence, our calculations are of
particular importance in obtaining this quantity, and have a significant rule
in the field of fission physics. Afterwards, our theoretical results have been
compared with the data obtained from the rotational liquid drop model as well
as the Sierk model, and satisfactory agreements were found. Finally, we have
considered the effective moment of inertia of compound nuclei for the systems
that formed similar compound nuclei at similar excitation energies.Comment: 9 pages, 2 Figures, 2 Table
The problem of lack of experience of graduates of technical specialties
В статье рассматриваются пути решения получения опыта работы для студентов. Опыт работы является одним из основных требований, предъявляемых к будущему работникуThe article discusses the solutions to obtain experience for students. Experience is one of the main requirements to the future employe
Technology of measurement of parameters of details on the GLOBAL CLASSIC coordinate measurement machine 05.05.05
Измерение сложнопрофильных деталей на предприятиях машиностроения без использования современного оборудования практически невозможно. Модернизация предприятий направлена не только на приобретение современного измерительного оборудования, но и на подготовку персоналаMeasurement of figurine details at the enterprises of mechanical engineering without use of the modern equipment is almost impossible. Modernization of the enterprises is directed not only to acquisition of the modern measuring equipment, but also to preparation of personne
Resonance Chiral Lagrangian analysis of decays
The hadronization structure of decays
is analyzed using Chiral Perturbation Theory with resonances, considering only
the contribution of the lightest meson resonances at leading order in the
expansion. After imposing the asymptotic behavior of vector spectral
functions ruled by QCD, unknown effective couplings are determined by fitting
the branching ratio and decay spectrum
to recent data. Predictions for the partner decay and the low-energy behavior of the cross section are also discussed.Comment: 21 pages, 5 figures, v2: Title changed, references added and
rewriting of some sentences. It matches the published version in PR
Bose-Einstein condensation of magnons under incoherent pumping
Bose-Einstein condensation in a gas of magnons pumped by an incoherent
pumping source is experimentally studied at room temperature. We demonstrate
that the condensation can be achieved in a gas of bosons under conditions of
incoherent pumping. Moreover, we show the critical transition point is almost
independent of the frequency spectrum of the pumping source and is solely
determined by the density of magnons. The electromagnetic power radiated by the
magnon condensate was found to scale quadratically with the pumping power,
which is in accordance with the theory of Bose-Einstein condensation in magnon
gases
TOF-Brho Mass Measurements of Very Exotic Nuclides for Astrophysical Calculations at the NSCL
Atomic masses play a crucial role in many nuclear astrophysics calculations.
The lack of experimental values for relevant exotic nuclides triggered a rapid
development of new mass measurement devices around the world. The
Time-of-Flight (TOF) mass measurements offer a complementary technique to the
most precise one, Penning trap measurements, the latter being limited by the
rate and half-lives of the ions of interest. The NSCL facility provides a
well-suited infrastructure for TOF mass measurements of very exotic nuclei. At
this facility, we have recently implemented a TOF-Brho technique and performed
mass measurements of neutron-rich nuclides in the Fe region, important for
r-process calculations and for calculations of processes occurring in the crust
of accreting neutron stars.Comment: 8 pages, 4 figures, submitted to Journal of Physics G, proceedings of
Nuclear Physics in Astrophysics II
Formation of deformation substructures in FCC crystals under the influence of point defect fluxes
The article deals with sub-structural transformations in FCC crystals under the influence of point defect fluxes. Different relationships between accumulation of point defects in crystal and substructure transformations, in particular during the process of fragmented dislocation structure formation have been received
Structural basis of second-generation HIV integrase inhibitor action and viral resistance
Despite worldwide prescription, the mechanistic basis for superiority of second-generation HIV integrase (IN) strand transfer inhibitors (INSTIs) is poorly understood. We use single-particle cryo-electron microscopy to visualize the mode of action of the advanced INSTIs dolutegravir and bictegravir at near atomic resolution. Q148H/G140S amino acid substitutions in IN that pervade clinical INSTI failure perturb optimal magnesium ion coordination in the enzyme active site. The expanded chemical scaffolds of second-generation compounds mediate interactions with the protein backbone, which are critical for antagonizing Q148H/G140S mutant virus. Our results reveal that binding to magnesium ions underpins a fundamental weakness of the INSTI pharmacophore that is exploited by the virus to engender resistance and provide a structural framework for the development of this important class of anti-HIV/AIDS therapeutics
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