Cutting the same fraction of several measures

We study some measure partition problems: Cut the same positive fraction of $d+1$ measures in $\mathbb R^d$ with a hyperplane or find a convex subset of $\mathbb R^d$ on which $d+1$ given measures have the same prescribed value. For both problems positive answers are given under some additional assumptions.Comment: 7 pages 2 figure

Voltage Responses to Optical Pulses of Unbiased Normal and Superconducting Samples

The direct transformation of the energy of an incident high-energy photon into a measurable potential difference within an absorbing metal is investigated. Experimental evidence is presented that the effect arises from the inherent energy dependence of the electronic density of states, rather than from a simple temperature excursion. The similarities between the results on Al and YBa2Cu3O7 samples indicate that the effect is universal in nature. We assert it may be used as the basis of a fast, energy resolving, individual photon detector for the ultraviolet radiation and x-rays

Chemomagnetism, magnetoconcentration effect and "fishtail" anomaly in chemically-induced granular superconductors

Within a 2D model of Josephson junction arrays (created by 2D network of twin boundary dislocations with strain fields acting as insulating barrier between hole-rich domains in underdoped crystals), a few novel effects expected to occur in intrinsically granular material are predicted including: (i) Josephson chemomagnetism (chemically induced magnetic moment in zero applied magnetic field) and its influence on a low-field magnetization (chemically induced paramagnetic Meissner effect), and (ii) magnetoconcentration effect (creation of oxygen vacancies in applied magnetic field) and its influence on a high-field magnetization (chemically induced analog of "fishtail" anomaly). The conditions under which these effects can be experimentally measured in non-stoichiometric high-T_c superconductors are discussed.Comment: 5 LaTeX pages (jetpl.sty included), 3 EPS figures. To be published in JETP Letters (January 2003

НЕКОТОРЫЕ ДАННЫЕ ПО ФАУНЕ ПАРАЗИТИЧЕСКИХ НЕМАТОД ВИНОГРАДА НА ТЕРРИТОРИИ НАГОРНОГО КАРАБАХА

Parasitic fauna of grapes in Martuninsk District of Nagorno-Karabakh is in-vestigated. Soil samples were collected at the deepness of 10–20 and 20–40 cm. Release of nematodes from soil was carried out using standard methods. Plant roots were examined for nematodes under a binocular microscope. Identification of the genus and species was conducted using temporary and permanent glycerin drugs. Parasitic fauna of examined grapes is represented by 5 genera (Xiphinema, Lon-gidorus, Helicotylenchus, Rotylenchus, Macroposthonia). 7 species were indenti-fied: Helicotylenchus digonicus, H. dihistera, H. pseudorobustus, Macroposthonia xenoplax, Xiphinema brevicolle, X. index, X. pachtaicum. Nematodes Xiphinema – transmitters of viruses are detected in rhizosphere of damaged grape plants; these plant-parasitic nematodes are of a great economic importance because of their spe-cific pathogenic effect; besides their direct harmful effect on plant’s root system they transmit various virus infections: grapevine leafroll virus, Arabis mosaic virus etc.Изучена паразитофауна виноградников Марту-нийского района Нагорного Карабаха. Пробы почвы отбирали на глубине 10-20 и 20-40 см. Выделение нематод из почвы проводили общепринятыми мето-дами. Корни растений исследовали на наличие нематод под бинокуляром. Идентификацию до рода и вида проводили на временных и постоянных глице-риновых препаратах. Паразитофауна исследо-ванных виноградников представлена 5 родами ( Xiphinema, Longidorus, Helicotylenchus, Rotylenchus, Macropos-thonia ). Идентифицировано 7 видов: Helicotylenchus digonicus, H. dihistera, H. pseudorobustus, Macroposthonia xenoplax, Xiphinema brevicolle, X. index, X. pachtaicum. В ризосфере угнетенных растений винограда обна-ружены нематоды - вирусоносители рода Xiphinema, имеющие большое экономическое значение как пара-зиты специфичного патогенного эффекта, кото-рые, кроме непосредственного вредоносного действия на корневую систему растений, являются перенос-чиками различной вирусной инфекции: вируса ве-еровидности листьев винограда, вируса мозаики и др

Luminescence spectra and kinetics of disordered solid solutions

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of “radiative” states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the “radiative” localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS(1−c)Sec and ZnSe(1−c)Tec solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated “radiative” states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence

Injection of Pseudomonas aeruginosa Exo Toxins into Host Cells Can Be Modulated by Host Factors at the Level of Translocon Assembly and/or Activity

Pseudomonas aeruginosa type III secretion apparatus exports and translocates four exotoxins into the cytoplasm of the host cell. The translocation requires two hydrophobic bacterial proteins, PopB and PopD, that are found associated with host cell membranes following infection. In this work we examined the influence of host cell elements on exotoxin translocation efficiency. We developed a quantitative flow cytometry based assay of translocation that used protein fusions between either ExoS or ExoY and the ß-lactamase reporter enzyme. In parallel, association of translocon proteins with host plasma membranes was evaluated by immunodetection of PopB/D following sucrose gradient fractionation of membranes. A pro-myelocytic cell line (HL-60) and a pro-monocytic cell line (U937) were found resistant to toxin injection even though PopB/D associated with host cell plasma membranes. Differentiation of these cells to either macrophage- or neutrophil-like cell lines resulted in injection-sensitive phenotype without significantly changing the level of membrane-inserted translocon proteins. As previous in vitro studies have indicated that the lysis of liposomes by PopB and PopD requires both cholesterol and phosphatidyl-serine, we first examined the role of cholesterol in translocation efficiency. Treatment of sensitive HL-60 cells with methyl-ß-cyclodextrine, a cholesterol-depleting agent, resulted in a diminished injection of ExoS-Bla. Moreover, the PopB translocator was found in the membrane fraction, obtained from sucrose-gradient purifications, containing the lipid-raft marker flotillin. Examination of components of signalling pathways influencing the toxin injection was further assayed through a pharmacological approach. A systematic detection of translocon proteins within host membranes showed that, in addition to membrane composition, some general signalling pathways involved in actin polymerization may be critical for the formation of a functional pore. In conclusion, we provide new insights in regulation of translocation process and suggest possible cross-talks between eukaryotic cell and the pathogen at the level of exotoxin translocation

Cerebrovascular reactivity among native-raised high altitude residents: an fMRI study

Background: The impact of long term residence on high altitude (HA) on human brain has raised concern among researchers in recent years. This study investigated the cerebrovascular reactivity among native-born high altitude (HA) residents as compared to native sea level (SL) residents. The two groups were matched on the ancestral line, ages, gender ratios, and education levels. A visual cue guided maximum inspiration task with brief breath holding was performed by all the subjects while Blood-Oxygenation-Level-Dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) data were acquired from them