1,403 research outputs found
The relation between SAR and the electromagnetic field distribution for heterogeneous exposure conditions
C
Magnetic flux pumping in 3D nonlinear magnetohydrodynamic simulations
A self-regulating magnetic flux pumping mechanism in tokamaks that maintains
the core safety factor at , thus preventing sawteeth, is analyzed
in nonlinear 3D magnetohydrodynamic simulations using the M3D-C code. In
these simulations, the most important mechanism responsible for the flux
pumping is that a saturated quasi-interchange instability generates
an effective negative loop voltage in the plasma center via a dynamo effect. It
is shown that sawtoothing is prevented in the simulations if is
sufficiently high to provide the necessary drive for the
instability that generates the dynamo loop voltage. The necessary amount of
dynamo loop voltage is determined by the tendency of the current density
profile to centrally peak which, in our simulations, is controlled by the
peakedness of the applied heat source profile.Comment: submitted to Physics of Plasmas (23 pages, 15 Figures
Evolution of the neutron quasi-elastic scattering through the ferroelectric phase transition in 93%PbZnNbO - 7% PbTiO
We show that the neutron diffuse scattering in relaxor ferroelectric
(1-x)PbZnNbO - x PbTiO (x=0.07) consists of two
components. The first component is strictly elastic but extended in q-space and
grows below 600 K. The second component, that was not reported before for the
(1-x)PbZnNbO - x PbTiO (x=0.07) relaxor
ferroelectrics, is quasi-elastic with a line-width that has a similar
temperature dependence as the width of the central peak observed by Brillouin
spectroscopy. The temperature dependence of the susceptibility of the
quasi-elastic scattering has a maximum at the ferroelectric transition
СТРАТЕГІЇ НАВЧАННЯ ТА ОЦІНЮВАННЯ В УМОВАХ ДИСТАНЦІЙНОГО ВИКЛАДАННЯ ІНОЗЕМНИХ МОВ
The article deals with the leading strategies for organizing students’ learning and assessment in the distance teaching of foreign languages. The work analyzes available online teaching methods and forms, and the most optimal ways, types, and methods of assessing students’ work on the currently available online platforms. The authors claim that pedagogical approaches to teaching foreign languages constantly require the search for new tools that can bring an element of novelty to the educational process while simultaneously increasing the interest of applicants, especially during the current (Covid-19) quarantine period.У статті розглянуто провідні стратегії організації навчання та оцінювання студентів в умовах дистанційного викладання іноземних мов. У роботі проаналізовано доступні інтерактивні методики та форми навчання, узагальнено найоптимальніші способи, форми і методи оцінювання роботи студентів на онлайн-платформах, доступних у даний час. Автори стверджують, що педагогічні підходи до викладання іноземних мов постійно вимагають пошуку новітніх засобів, які здатні привнести в навчальний процес елемент новизни, підвищити інтерес здобувачів вищої освіти, особливо в період карантину
Pseudo-laminar chaos from on-off intermittency
In finite-dimensional, chaotic, Lorenz-like wave-particle dynamical systems
one can find diffusive trajectories, which share their appearance with that of
laminar chaotic diffusion [Phys. Rev. Lett. 128, 074101 (2022)] known from
delay systems with lag-time modulation. Applying, however, to such systems a
test for laminar chaos, as proposed in [Phys. Rev. E 101, 032213 (2020)], these
signals fail such test, thus leading to the notion of pseudo-laminar chaos. The
latter can be interpreted as integrated periodically driven on-off
intermittency. We demonstrate that, on a signal level, true laminar and
pseudo-laminar chaos are hardly distinguishable in systems with and without
dynamical noise. However, very pronounced differences become apparent when
correlations of signals and increments are considered. We compare and contrast
these properties of pseudo-laminar chaos with true laminar chaos.Comment: 13 pages, 7 figure
Cell cycle progression or translation control is not essential for vesicular stomatitis virus oncolysis of hepatocellular carcinoma.
The intrinsic oncolytic specificity of vesicular stomatitis virus (VSV) is currently being exploited to develop alternative therapeutic strategies for hepatocellular carcinoma (HCC). Identifying key regulators in diverse transduction pathways that define VSV oncolysis in cancer cells represents a fundamental prerequisite to engineering more effective oncolytic viral vectors and adjusting combination therapies. After having identified defects in the signalling cascade of type I interferon induction, responsible for attenuated antiviral responses in human HCC cell lines, we have now investigated the role of cell proliferation and translation initiation. Cell cycle progression and translation initiation factors eIF4E and eIF2Bepsilon have been recently identified as key regulators of VSV permissiveness in T-lymphocytes and immortalized mouse embryonic fibroblasts, respectively. Here, we show that in HCC, decrease of cell proliferation by cell cycle inhibitors or siRNA-mediated reduction of G(1) cyclin-dependent kinase activities (CDK4) or cyclin D1 protein expression, do not significantly alter viral growth. Additionally, we demonstrate that translation initiation factors eIF4E and eIF2Bepsilon are negligible in sustaining VSV replication in HCC. Taken together, these results indicate that cellular proliferation and the initiation phase of cellular protein synthesis are not essential for successful VSV oncolysis of HCC. Moreover, our observations indicate the importance of cell-type specificity for VSV oncolysis, an important aspect to be considered in virotherapy applications in the future
An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems
Recent developments in the study of ultracold Rydberg gases demand an
advanced level of experimental sophistication, in which high atomic and optical
densities must be combined with excellent control of external fields and
sensitive Rydberg atom detection. We describe a tailored experimental system
used to produce and study Rydberg-interacting atoms excited from dense
ultracold atomic gases. The experiment has been optimized for fast duty cycles
using a high flux cold atom source and a three beam optical dipole trap. The
latter enables tuning of the atomic density and temperature over several orders
of magnitude, all the way to the Bose-Einstein condensation transition. An
electrode structure surrounding the atoms allows for precise control over
electric fields and single-particle sensitive field ionization detection of
Rydberg atoms. We review two experiments which highlight the influence of
strong Rydberg--Rydberg interactions on different many-body systems. First, the
Rydberg blockade effect is used to pre-structure an atomic gas prior to its
spontaneous evolution into an ultracold plasma. Second, hybrid states of
photons and atoms called dark-state polaritons are studied. By looking at the
statistical distribution of Rydberg excited atoms we reveal correlations
between dark-state polaritons. These experiments will ultimately provide a
deeper understanding of many-body phenomena in strongly-interacting regimes,
including the study of strongly-coupled plasmas and interfaces between atoms
and light at the quantum level.Comment: 14 pages, 11 figures; submitted to a special issue of 'Frontiers of
Physics' dedicated to 'Quantum Foundation and Technology: Frontiers and
Future
Seasonal progression of active-layer thickness dependent on microrelief
Introduction
Active-layer thickness is a major factor for all physical and biological processes in permafrost soils. It is closely related to the fluxes of energy, water and carbon between permafrost landscapes and the atmosphere. Active-layer thickness is mainly driven by air temperature, but also influenced by snow cover, summer rainfall, soil properties and vegetation characteristics (Nelson et al., 1998). The typical polygonal tundra of the Lena Delta is characterised by a pronounced microrelief, which causes a high small-scale heterogeneity of soil and vegetation properties. Consequently, also the active-layer thickness varies substantially across small lateral distances of decimetres to metres. In order to up-scale results of process studies to the landscape scale, a quantification of the heterogeneity of active-layer thickness is of great interest
- …