3,192 research outputs found
Time-Evolution of a Fractal Distribution: Particle Concentrations in Free-Surface Turbulence
Steady-state turbulence is generated in a tank of water and the trajectories
of particles forming a compressible system on the surface are tracked in time.
The initial uniformly distributed floating particles coagulate and form a
fractal distribution, a rare manifestation of a fractal object observable in
real-space. The surface pattern reaches a steady state in approximately 1 s.
Measurements are made of the fractal dimensions ( to ) of the
floating particles starting with the uniform distribution = 2 for
Taylor Microscale Reynolds number . Focus is on the
the time-evolution of the correlation dimension as the steady state is
approached. This steady state is reached in several large eddy turnover times
and does so at an exponential rate
Vibrations of a chain of Xe atoms in a groove of carbon nanotube bundle
We present a lattice dynamics study of the vibrations of a linear chain of Xe
adsorbates in groove positions of a bundle of carbon nanotubes. The
characteristic phonon frequencies are calculated and the adsorbate polarization
vectors discussed. Comparison of the present results with the ones previously
published shows that the adsorbate vibrations cannot be treated as completely
decoupled from the vibrations of carbon nanotubes and that a significant
hybridization between the adsorbate and the tube modes occurs for phonons of
large wavelengths.Comment: 3 PS figure
Effective DBHF Method for Asymmetric Nuclear Matter and Finite Nuclei
A new decomposition of the Dirac structure of nucleon self-energies in the
Dirac Brueckner-Hartree-Fock (DBHF) approach is adopted to investigate the
equation of state for asymmetric nuclear matter. The effective coupling
constants of , , and mesons with a density
dependence in the relativistic mean field approach are deduced by reproducing
the nucleon self-energy resulting from the DBHF at each density for symmetric
and asymmetric nuclear matter. With these couplings the properties of finite
nuclei are investigated. The agreement of charge radii and binding energies of
finite nuclei with the experimental data are improved simultaneously in
comparison with the projection method. It seems that the properties of finite
nuclei are sensitive to the scheme used for the DBHF self-energy extraction. We
may conclude that the properties of the asymmetric nuclear matter and finite
nuclei could be well described by the new decomposition approach of the G
matrix.Comment: 16 pages, 5 figure
Anomalous Negative Magnetoresistance Caused by Non-Markovian Effects
A theory of recently discovered anomalous low-field magnetoresistance is
developed for the system of two-dimensional electrons scattered by hard disks
of radius randomly distributed with concentration For small magnetic
fields the magentoresistance is found to be parabolic and inversely
proportional to the gas parameter, With increasing field the magnetoresistance becomes linear
in a good agreement with the
experiment and numerical simulations.Comment: 4 pages RevTeX, 5 figure
Transport properties of copper phthalocyanine based organic electronic devices
Ambipolar charge carrier transport in Copper phthalocyanine (CuPc) is studied
experimentally in field-effect transistors and metal-insulator-semiconductor
diodes at various temperatures. The electronic structure and the transport
properties of CuPc attached to leads are calculated using density functional
theory and scattering theory at the non-equilibrium Green's function level. We
discuss, in particular, the electronic structure of CuPc molecules attached to
gold chains in different geometries to mimic the different experimental setups.
The combined experimental and theoretical analysis explains the dependence of
the mobilityand the transmission coefficient on the charge carrier type
(electrons or holes) and on the contact geometry. We demonstrate the
correspondence between our experimental results on thick films and our
theoretical studies of single molecule contacts. Preliminary results for
fluorinated CuPc are discussed.Comment: 18 pages, 16 figures; to be published in Eur. Phys. J. Special Topic
The low energy limit of the non-commutative Wess-Zumino model
The non-commutative Wess-Zumino model is used as a prototype for studying the
low energy behaviour of a renormalizable non-commutative field theory. We start
by deriving the potential mediating the fermion-fermion and boson-boson
interactions in the non-relativistic regime. The quantum counterparts of these
potentials are afflicted by irdering ambiguities but we show that there exists
an ordering prescription which makes them hermitean. For space/space
noncommutativity it turns out that Majorana fermions may be pictured as rods
oriented perpendicularly to the direction of motion showing a lack of
localituy, while bosons remain insensitive to the effects of noncommutativity.
For time/space noncommutativity bosopns and fermions can be regarded as rods
oriented along the direction of motion. For both cases of noncommutativity the
scattering state described scattered waves, with at least one wave having
negative time delay signalizing the underlying nonlocality. The superfield
formulation of the model is used to compute the corresponding effective action
in the one- and two-loop approximations. In the case of time/space
noncommutativity, unitarity is violated in the relativistic regime. However,
this does not preclude the existence of the unitary low energy limit.Comment: 14 pages, 2 figures, minor correction
Candidate Genes for Chromosomes 6 and 10: Quantitative Trait Loci for Age-Related Retinal Degeneration in Mice
Purpose: In a previous study, several quantitative trait loci (QTL) that influence age-related degeneration (ageRD) were identified in a cross between the albino strains B6(Cg)-Tyr(c-2J)/J (B6a) and BALB/cByJ (C). The Chromosome (Chr) 6 and Chr 10 QTL were the strongest and most highly significant loci and both involved B6a protective alleles. The QTL were responsible for 21% and 9% of the variance in phenotypes, respectively. We focused on these two QTL to identify candidate genes. Methods: DNA microarrays were used for the two mouse strains at four and eight months of age to identify genes that are differentially regulated and map to either QTL. Gene Ontology (GO) analysis of the differentially expressed genes was performed to identify possible processes and pathways associated with ageRD. To identify additional candidates, database analyses (Positional Medline or PosMed) were used. Based on differential expression, PosMed, and the presence of reported polymorphisms, five genes per QTL were selected for further study by sequencing analysis and qRT-PCR. Tumor necrosis factor, alpha-induced protein 3 (Tnfaip3; on a C57BL/6J (B6) background) was phenotypically tested. Single nucleotide polymorphisms (SNPs) flanking this gene were correlated with outer nuclear layer thickness (ONL), and eight-month-old Tnfaip3(+/-) mice were tested for ageRD. Results: Polymorphisms were found in the coding regions of eight genes. Changes in gene expression were identified by qRT-PCR for Hexokinase 2 (Hk2) and Docking protein 1 (Dok1) at four months and for Dok1 and Tnfaip3 at eight months. Tnfaip3 was selected for phenotypic testing due to differential expression and the presence of two nonsynonymous mutations. However, when ONL thickness was compared in eight-month-old congenic Tnfaip3(+/-) and Tnfaip3(+/+) mice, no differences were found, suggesting that Tnfaip3 is not the quantitative trait gene (QTG) for the Chr 10 QTL. The GO analysis revealed that GO terms associated with stress and cell remodeling are overrepresented in the ageRD-sensitive C strain compared with the B6a strain with age (eight months). In the ageRD-resistant B6a strain, compared with the C strain, GO terms associated with antioxidant response and the regulation of blood vessel size are overrepresented with age. Conclusions: The analyses of differentially expressed genes and the PosMed database yielded candidate genes for the Chr 6 and Chr 10 QTL. HtrA serine peptidase 2 (Htra2), Dok1, and Tnfaip3 were deemed most promising because of their known roles in apoptosis and our finding of nonsynonymous substitutions between B6a and C strains. While Tnfaip3 was excluded as the QTG for the Chr 10 QTL, Dok1 and Htra2 remain good candidates for the Chr 6 QTL. Finally, the GO term analysis further supports the general hypothesis that oxidative stress is involved in ageRD
Вибір допоміжних речовин з метою отримання таблеток на основі екстракту примули дрібнозубчастої методом вологої грануляції
Introduction. Herbal medicines are increasingly being used in the treatment of various diseases. Significant number of resources, high-level availability and the possibility of cultivation have provided high prospects of plant raw materials in the development of new herbal medicines. Primula denticulate Smith. is one of the most interesting medicinal plant raw materials source in modern medicine and pharmacy with the wide spectrum of pharmacotherapeutic action, that is mainly used only in traditional medicine. Thus, nowadays the development of new and effective medicines based on Primula denticulate Smith. in tablet dosage form is the topical task of pharmacy.
The aim of the work. To study the influence of excipients on the pharmacotechnological parameters of tablets with Primula denticulate Smith, are obtained by wet granulation method and to substantiate the choosing of the best excipients by the method of mathematical planning of the experiment.
Materials and Methods. It was used a self-prepared dense extract of Primula denticulate Smith. and excipients, which are complied with the requirements of State Pharmacopoeia of Ukraine in terms of pharmaco-technological quality parameters, for developing tablets. The hyper Greek-Latin square 4x4 was used to study the four qualitative factors.
Results and Discussion. In the course of the experiment, it was determined the dependence of pharmacotechnological parameters (friability, resistance to crushing and disintegration of tablets) on type of excipients. It was selected excipients with the optimal pharmaco-technological parameters for further research the tablets quality.
Conclusions.
According to the method of mathematical planning of the experiment, it’s chosen the optimal excipients for obtaining tablets based on dense extract of Primula denticulate Smith. Considering the investigated pharmaco-technological properties (friability, resistance to crushing and disintegration of tablets) the qualitative composition of excipients for obtaining tablets by the method of wet granulation was determined: Avicel PH - 105 and MCC 101, croscarmellose sodium, colloidal anhydrous silicon dioxide, magnesium stearate and Prosolv 90.Актуальность. Лекарственные средства на основе растительного сырья все чаще находят применение при лечении различных заболеваний. Значительные ресурсы, доступность и возможность культивации обеспечивают высокую перспективность растительного сырья при разработке новых лекарственных средств растительного происхождения.
Одним из источников лекарственного растительного сырья, который представляет особенный интерес для современной медицины и фармации вследствие широкого фармакотерапевтического спектра действия, – является примула мелкозубчатая, которая в основном используется только в народной медицине. Таким образом, в настоящее время актуальной задачей фармации является разработка новых и эффективных лекарственных средств на основе примулы мелкозубчатой в таблетированной лекарственной форме.
Цель работы. Изучение влияния вспомогательных веществ (ВВ) на фармако-технологические показатели таблеток, которые содержат густой экстракт примулы мелко мелкозубчатой, полученных методом влажной грануляции и обоснование выбора оптимальных ВВ методом математического планирования эксперимента.
Материалы и методы. При разработке таблетированного лекарственного средства использовали самостоятельно приготовленный густой экстракт примулы мелкозубчатой и вспомогательные вещества, которые соответствуют требованиям ГФУ по фармако-технологическим показателям качества для таблетированных препаратов. Для реализации эксперимента использовали математическое планирование, а именно, четырехфакторный анализ на основе гипер-греко латинского квадрата.
Результаты и их обсуждение. В ходе исследования определили зависимость экспериментальных показателей (истираемость, устойчивость к раздавливанию и распадаемость) от вида вспомогательных веществ, которые входили в состав таблеток согласно определенного плана эксперимента. Для дальнейших исследований были отобраны вспомогательные вещества, которые отличались оптимальными фармако-технологическими параметрами качества исследуемых таблеток.
Выводы. Используя метод математического планирования эксперимента, выбраны оптимальные вспомогательные вещества для производства таблеток на основе густого экстракта примулы мелкозубчатой. На основании исследованных фармако-технологических свойств (истираемость, устойчивость к раздавливанию и распадаемость таблеток) определен качественный состав вспомогательных веществ для получения таблеток методом влажной грануляции: Avicel PH – 105 и МКЦ 101, натрия кроскармелоза, кремния диоксид коллоидный безводный, магния стеарат и просолв 90.Актуальність. Лікарські засоби на основі рослинної сировини все частіше застосовуються при лікуванні багатьох захворювань. Значні ресурси, доступність та можливість культивування, - роблять рослинну сировину дуже перспективною при розробці нових лікарських засобів рослинного походження.
Одним з джерел, що представляє особливий інтерес для сучасної медицини та фармації внаслідок широкого спектра фармакотерапевтичної дії – є примула дрібнозубчаста, яка в основному використовуються тільки в народній медицині. Тому розробка нових та ефективних лікарських засобів на основі примули дрібнозубчастої у таблетованій формі є актуальним завданням сьогодення.
Мета. Вивчення впливу допоміжних речовин (ДР) на фармако-технологічні показники таблеток, що містять густий екстракт примули дрібнозубчастої, отриманих методом вологої грануляції та обґрунтування вибору кращих ДР при розробці таблетованого лікарського засобу із застосуванням методу математичного планування експерименту.
Матеріали та методи. При розробці таблетованого засобу використовували густий екстракт примули дрібнозубчастої, який отримували самостійно, та допоміжні речовини, які відповідають вимогам ДФУ і забезпечують виконання всіх фармако-технологічних показників якості таблетованих препаратів. Для реалізації експерименту використовували математичне планування, а саме чотирьох факторний план на основі гіпер-греко латинського квадрату.
Результати та їх обговорення. У процесі досліджень визначили залежність усіх досліджуваних показників (стираність, стійкість таблеток до роздавлювання та час розпадання) від допоміжних речовин, які водилися в склад таблеток на основі густого екстракту примули дрібнозубчастої, згідно вибраного плану експерименту. На основі аналізу було відібрано для подальших досліджень допоміжні речовини, які чинили максимальний ефект на основні фармако-технологічні показники якості досліджуваних таблеток.
Висновки. Використовуючи метод математичного планування експерименту, визначили оптимальні допоміжні речовини для виробництва таблеток на основі густого екстракту примули дрібнозубчастої. На підставі показників таблеток (час розпадання, стираність, стійкість до роздавлювання) визначили якісний склад допоміжних речовин для отримання таблеток методом вологої грануляції: Avicel PH – 105 та МКЦ 101, натрію кроскармельоза, кремнію діоксид колоїдний безводний, магнію стеарат та просолв 90
The structure of superheavy elements newly discovered in the reaction of Kr with Pb
The structure of superheavy elements newly discovered in the
Pb(Kr,n) reaction at Berkeley is systematically studied in the
Relativistic Mean Field (RMF) approach. It is shown that various usually
employed RMF forces, which give fair description of normal stable nuclei, give
quite different predictions for superheavy elements. Among the effective forces
we tested, TM1 is found to be the good candidate to describe superheavy
elements. The binding energies of the 118 nucleus and its
decay daughter nuclei obtained using TM1 agree with those of FRDM
within 2 MeV. Similar conclusion that TM1 is the good interaction is also drawn
from the calculated binding energies for Pb isotopes with the Relativistic
Continuum Hartree Bogoliubov (RCHB) theory. Using the pairing gaps obtained
from RCHB, RMF calculations with pairing and deformation are carried out for
the structure of superheavy elements. The binding energy, shape, single
particle levels, and the Q values of the decay are
discussed, and it is shown that both pairing correlation and deformation are
essential to properly understand the structure of superheavy elements. A good
agreement is obtained with experimental data on . %Especially, the
atomic number %dependence of %seems to match with the experimental
observationComment: 19 pages, 5 figure
Non-Markovian entanglement dynamics in coupled superconducting qubit systems
We theoretically analyze the entanglement generation and dynamics by coupled
Josephson junction qubits. Considering a current-biased Josephson junction
(CBJJ), we generate maximally entangled states. In particular, the entanglement
dynamics is considered as a function of the decoherence parameters, such as the
temperature, the ratio between the reservoir cutoff
frequency and the system oscillator frequency , % between
the characteristic frequency of the %quantum system of interest, and
the cut-off frequency of %Ohmic reservoir and the energy levels
split of the superconducting circuits in the non-Markovian master equation. We
analyzed the entanglement sudden death (ESD) and entanglement sudden birth
(ESB) by the non-Markovian master equation. Furthermore, we find that the
larger the ratio and the thermal energy , the shorter the
decoherence. In this superconducting qubit system we find that the entanglement
can be controlled and the ESD time can be prolonged by adjusting the
temperature and the superconducting phases which split the energy
levels.Comment: 13 pages, 3 figure
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