599 research outputs found

    Level Crossing Rate of Macrodiversity System in the Presence of Multipath Fading and Shadowing

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    Macrodiversity system including macrodiversity SC receiver and two microdiversity SC receivers is considered in this paper. Received signal experiences, simultaneously, both, long term fading and short term fading. Microdiversity SC receivers reduces Rayleigh fading effects on system performance and macrodiversity SC receiver mitigate Gamma shadowing effects on system performance. Closed form expressions for level crossing rate of microdiversity SC receivers output signals envelopes are calculated. This expression is used for evaluation of level crossing rate of macrodiversity SC receiver output signal envelope. Numerical expressions are illustrated to show the influence of Gamma shadowing severity on level crossing rate

    Compressive Inverse Scattering II. SISO Measurements with Born scatterers

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    Inverse scattering methods capable of compressive imaging are proposed and analyzed. The methods employ randomly and repeatedly (multiple-shot) the single-input-single-output (SISO) measurements in which the probe frequencies, the incident and the sampling directions are related in a precise way and are capable of recovering exactly scatterers of sufficiently low sparsity. For point targets, various sampling techniques are proposed to transform the scattering matrix into the random Fourier matrix. The results for point targets are then extended to the case of localized extended targets by interpolating from grid points. In particular, an explicit error bound is derived for the piece-wise constant interpolation which is shown to be a practical way of discretizing localized extended targets and enabling the compressed sensing techniques. For distributed extended targets, the Littlewood-Paley basis is used in analysis. A specially designed sampling scheme then transforms the scattering matrix into a block-diagonal matrix with each block being the random Fourier matrix corresponding to one of the multiple dyadic scales of the extended target. In other words by the Littlewood-Paley basis and the proposed sampling scheme the different dyadic scales of the target are decoupled and therefore can be reconstructed scale-by-scale by the proposed method. Moreover, with probes of any single frequency \om the coefficients in the Littlewood-Paley expansion for scales up to \om/(2\pi) can be exactly recovered.Comment: Add a new section (Section 3) on localized extended target

    Inhibition of c-Kit signaling is associated with reduced heat and cold pain sensitivity in humans

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    The tyrosine kinase receptor c-Kit is critically involved in the modulation of nociceptive sensitivity in mice. Ablation of the c-Kit gene results in hyposensitivity to thermal pain, while c-Kit activation produces hypersensitivity to the noxious heat, without altering sensitivity to innocuous mechanical stimuli. In this study we investigated the role of c-Kit signalling in human pain perception. We hypothesized that subjects treated with Imatinib or Nilotinib, potent inhibitors of tyrosine kinases including c-Kit, but also Abl1, PDFGFR{alpha}, and PDFGFR{beta}, that are used to treat chronic myeloid leukemia (CML), would experience changes in thermal pain sensitivity. We examined 31 asymptomatic CML patients (14 male, 17 female) under Imatinib/Nilotinib treatment and compared them to 39 age- and sex-matched healthy controls (12 male, 27 female). We used cutaneous heat and cold stimulation to test normal and noxious thermal sensitivity, and a grating orientation task to assess tactile acuity. Thermal pain thresholds were significantly increased in the Imatinib/Nilotinib-treated group, while innocuous thermal and tactile thresholds were unchanged compared to the control group. In conclusion, our findings suggest that the biological effects of c-Kit inhibition are comparable in mice and humans in that c-Kit activity is required to regulate thermal pain sensitivity, but does not affect innocuous thermal and mechanical sensation. The effect on experimental heat pain observed in our study is comparable to that of several common analgesics, thus modulation of the c-Kit pathway can be used to specifically modulate noxious heat and cold sensitivity in humans

    Covariation Among Vowel Height Effects on Acoustic Measures

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    Covariation among vowel height effects on vowel intrinsic fundamental frequency (IF0), voice onset time (VOT), and voiceless interval duration (VID) is analyzed to assess the plausibility of a common physiological mechanism underlying variation in these measures. Phrases spoken by 20 young adults, containing words composed of initial voiceless stops or /s/ and high or low vowels, were produced in habitual and voluntarily increased F0 conditions. High vowels were associated with increased IF0 and longer VIDs. VOT and VID exhibited significant covariation with IF0 only for males at habitua

    Cell-Autonomous Death of Cerebellar Purkinje Neurons with Autophagy in Niemann-Pick Type C Disease

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    Niemann-Pick type C is a neurodegenerative lysosomal storage disorder caused by mutations in either of two genes, npc1 and npc2. Cells lacking Npc1, which is a transmembrane protein related to the Hedgehog receptor Patched, or Npc2, which is a secreted cholesterol-binding protein, have aberrant organelle trafficking and accumulate large quantities of cholesterol and other lipids. Though the Npc proteins are produced by all cells, cerebellar Purkinje neurons are especially sensitive to loss of Npc function. Since Niemann-Pick type C disease involves circulating molecules such as sterols and steroids and a robust inflammatory response within the brain parenchyma, it is crucial to determine whether external factors affect the survival of Purkinje cells (PCs). We investigated the basis of neurodegeneration in chimeric mice that have functional npc1 in only some cells. Death of mutant npc1 cells was not prevented by neighboring wild-type cells, and wild-type PCs were not poisoned by surrounding mutant npc1 cells. PCs undergoing cell-autonomous degeneration have features consistent with autophagic cell death. Chimeric mice exhibited a remarkable delay and reduction of wasting and ataxia despite their substantial amount of mutant tissue and dying cells, revealing a robust mechanism that partially compensates for massive PC death

    Circulating anthocyanin metabolites mediate vascular benefits of blueberries:insights from randomized controlled trials, metabolomics, and nutrigenomics

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    Potential health benefits of blueberries may be due to vascular effects of anthocyanins which predominantly circulate in blood as phenolic acid metabolites. We investigated which role blueberry anthocyanins and circulating metabolites play in mediating improvements in vascular function and explore potential mechanisms using metabolomics and nutrigenomics. Purified anthocyanins exerted a dose-dependent improvement of endothelial function in healthy humans, as measured by flow-mediated dilation (FMD). The effects were similar to those of blueberries containing similar amounts of anthocyanins while control drinks containing fiber, minerals, or vitamins had no significant effect. Daily 1-month blueberry consumption increased FMD and lowered 24h-ambulatory-systolic-blood-pressure. Of the 63 anthocyanin plasma metabolites quantified, 14 and 17 correlated with acute and chronic FMD improvements, respectively. Injection of these metabolites improved FMD in mice. Daily blueberry consumption led to differential expression (>1.2-fold) of 608 genes and 3 microRNAs, with Mir-181c showing a 13-fold increase in peripheral blood mononuclear cells. Patterns of 13 metabolites were independent predictors of gene expression changes and pathway enrichment analysis revealed significantly modulated biological processes involved in cell adhesion, migration, immune response, and cell differentiation. Our results identify anthocyanin metabolites as major mediators of vascular bioactivities of blueberries and changes of cellular gene programs

    Immobilization of Co-60 and Sr-90 Ions Using Red Mud from Aluminum Industry

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    The removal of Co-60 and Sr-90 from the aqueous phase was tested using red mud - the fine grained residue from bauxite ore processing. This industrial waste represents a mixture of numerous minerals, mainly oxides and hydroxides of Fe, Al, Si, and Ti. Experiments were conducted as a function of contact time, pH, and pollutant concentrations. Kinetic data were well fitted with a pseudo-second order equation. The calculated rate constants and initial sorption rates indicated faster sorption of Sr2+ ions. Removal of both cations rapidly increased with the initial pH increase from 2.5 to 3.5. With the further increase of pH, Co2+ sorption was nearly constant (98%-100%), whereas Sr2+ removal remained at the same level to initial pH similar to 8 and gradually increased to 100% at pH 12. Equilibrium sorption data followed the Langmuir model, with the maximum sorption capacities of 0.52 mmol/g for Co2+ and 0.31 mmol/g for Sr2+. Sorbed cations exhibited high stability in distilled water. Desorption of Co2+ was also negligible in the presence of the competing Ca2+ cation, while 42%-25% of Sr2+ ions were desorbed depending on the previously sorbed amount. The results indicate that red mud is of potential significance as Co2+ and Sr2+ immobilization agent due to its high efficiency, abundance, and low-cost

    Pitch strength of normal and dysphonic voices

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    Two sounds with the same pitch may vary from each other based on saliency of their pitch sensation. This perceptual attribute is called “pitch strength.” The study of voice pitch strength may be important in quantifying of normal and pathological qualities. The present study investigated how pitch strength varies across normal and dysphonic voices. A set of voices (vowel /a/) selected from the Kay Elemetrics Disordered Voice Database served as the stimuli. These stimuli demonstrated a wide range of voice quality. Ten listeners judged the pitch strength of these stimuli in an anchored magnitude estimation task. On a given trial, listeners heard three different stimuli. The first stimulus represented very low pitch strength (wide-band noise), the second stimulus consisted of the target voice and the third stimulus represented very high pitch strength (pure tone). Listeners estimated pitch strength of the target voice by positioning a continuous slider labeled with values between 0 and 1, reflecting the two anchor stimuli. Results revealed that listeners can judge pitch strength reliably in dysphonic voices. Moderate to high correlations with perceptual judgments of voice quality suggest that pitch strength may contribute to voice quality judgments
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