6,215 research outputs found
Long-distance transfer of microwaves in sliding-mode virtual plasma waveguides
Experimentally an effective channeling and transfer of the sliding
mode of the 35.3 GHz (λ â 8.5 mm) microwave signal along 60 m distance has been
demonstrated in the low-density (ne ⌠1012 cmâ3) 10 cm diameter hollow plasma
waveguide created by the 100 ns UV pulse of GARPUN KrF laser in the laboratory
air. The mechanism of the transfer is the total internal reflection of the signal on
the optically less dense walls of the waveguide. The theory of this sliding mode
propagation in large-diameter (D ïżœ λ) plasma waveguides is developed, which is in
good accordance with our experimental results
Phase Diagram of Multilayer Magnetic Structures
Multilayer "ferromagnet-layered antiferromagnet" (Fe/Cr) structures
frustrated due to the roughness of layer interfaces are studied by numerical
modeling methods. The "thickness-roughness" phase diagrams for the case of thin
ferromagnetic film on the surface of bulk antiferromagnet and for two
ferromagnetic layers separated by an antiferromagnetic interlayer are obtained
and the order parameter distributions for all phases are found. The phase
transitions nature in such systems is considered. The range of applicability
for the "magnetic proximity model" proposed by Slonczewski is evaluated.Comment: 8 pages, 8 figure
Charged-Surface Instability Development in Liquid Helium; Exact Solutions
The nonlinear dynamics of charged-surface instability development was
investigated for liquid helium far above the critical point. It is found that,
if the surface charge completely screens the field above the surface, the
equations of three-dimensional (3D) potential motion of a fluid are reduced to
the well-known equations describing the 3D Laplacian growth process. The
integrability of these equations in 2D geometry allows the analytic description
of the free-surface evolution up to the formation of cuspidal singularities at
the surface.Comment: latex, 5 pages, no figure
Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape
We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064â
nm pulsed beams propagate from wider (122â
”m) into smaller (37â
”m) diameter. In the passive mode, increasing the input beam peak power above 20â
kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600â
nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length
Bulk and local magnetic susceptibility of ErB12
High precision measurements of magnetoresistance ÎÏ/Ï = f(T,H) and magnetization M(T,H) were carried out on single crystals of rare-earth dodecaboride at temperatures in the interval 1.8-30 K in magnetic fields up to 70 kOe. The high accuracy of the experiments allowed us to perform numerical differentiation and analyze quantitatively the behavior of the derivative d(ÎÏ/Ï)/dH = f(T,H) and of the magnetic susceptibility Ï(T,H) = dM/dH in paramagnetic and magnetically ordered (antiferromagnetic, â 6.7 K and â 5.85 K) phases of . It was shown that negative magnetoresistance anomalies observed in present study in paramagnetic state of may be consistently interpreted in the framework of a simple relation between resistivity and magnetization -ÎÏ/Ï ~
Changes in the Intestinal Microbiota in Patients with Chronic Pancreatitis: Systematizing Literature Data
The purpose of the review. To systematize literature data on changes in the structure of the intestinal microbiota in patients with chronic pancreatitis (CP).Key findings. The human intestinal microbiota is a dynamically changing system that is constantly undergoing qualitative and quantitative changes, especially in several pathological conditions of the digestive system. At present, the differences in the intestinal microbiota in pancreatic diseases are poorly understood. The severe CP is associated with impaired synthesis of antimicrobial peptides, bicarbonates, and digestive enzymes by the pancreas, which is a risk factor for dysbiotic changes in the intestinal microbiota, consisting in the development of small intestinal bacterial overgrowth (SIBO) and gut dysbiosis. The results of two large meta-analyses show that about a third of CP patients have SIBO. The colonic microbiota in patients with CP is also characterized by dysbiotic disorders, primarily in the reduction of alpha-diversity. Some studies have shown that these patients have an increase in Firmicutes, while Bacteroides and Faecalibacterium are reduced. In addition, as a rule, in patients with CP, the growth of Escherichia, Shigella and Streptococcus is recorded.Conclusion. In general, scientific papers have revealed significant heterogeneity in the profiles of the intestinal microbiota in patients with CP. Thus, several questions remain open, prioritizing the further study of the intestinal microbiota in patients with CP for identifying the specifics of its structure that can personalize the selection of enzyme replacement therapy and restrict the unreasonable prescription of additional pharmacotherapy (the use of proton pump inhibitors and / or antibacterial drugs)
Relaxation and edge reconstruction in integer quantum Hall systems
The interplay between the confinement potential and electron-electron
interactions causes reconstructions of Quantum Hall edges. We study the
consequences of this edge reconstruction for the relaxation of hot electrons
injected into integer quantum Hall edge states. In translationally invariant
edges, the relaxation of hot electrons is governed by three-body collisions
which are sensitive to the electron dispersion and thus to reconstruction
effects. We show that the relaxation rates are significantly altered in
different reconstruction scenarios.Comment: 8 pages, 3 figure
Stratus Not Altocumulus: A New View of the Yeast Protein Interaction Network
Systems biology approaches can reveal intermediary levels of organization between genotype and phenotype that often underlie biological phenomena such as polygenic effects and protein dispensability. An important conceptualization is the module, which is loosely defined as a cohort of proteins that perform a dedicated cellular task. Based on a computational analysis of limited interaction datasets in the budding yeast Saccharomyces cerevisiae, it has been suggested that the global protein interaction network is segregated such that highly connected proteins, called hubs, tend not to link to each other. Moreover, it has been suggested that hubs fall into two distinct classes: âpartyâ hubs are co-expressed and co-localized with their partners, whereas âdateâ hubs interact with incoherently expressed and diversely localized partners, and thereby cohere disparate parts of the global network. This structure may be compared with altocumulus clouds, i.e., cotton ballâlike structures sparsely connected by thin wisps. However, this organization might reflect a small and/or biased sample set of interactions. In a multi-validated high-confidence (HC) interaction network, assembled from all extant S. cerevisiae interaction data, including recently available proteome-wide interaction data and a large set of reliable literature-derived interactions, we find that hubâhub interactions are not suppressed. In fact, the number of interactions a hub has with other hubs is a good predictor of whether a hub protein is essential or not. We find that date hubs are neither required for network tolerance to node deletion, nor do date hubs have distinct biological attributes compared to other hubs. Date and party hubs do not, for example, evolve at different rates. Our analysis suggests that the organization of global protein interaction network is highly interconnected and hence interdependent, more like the continuous dense aggregations of stratus clouds than the segregated configuration of altocumulus clouds. If the network is configured in a stratus format, cross-talk between proteins is potentially a major source of noise. In turn, control of the activity of the most highly connected proteins may be vital. Indeed, we find that a fluctuation in steady-state levels of the most connected proteins is minimized
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