802 research outputs found

    Влияние глобальных климатических изменений на размеры косточек среднего уха

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    Department of Anatomy and Anthropology Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel, Department of Otorhinolaryngology Head Neck Surgery, The Sheba Medical Center, Tel-Hashomer, Conferinţa Știinţifică Internaţională ”Probleme actuale ale morfologiei” dedicată сentenarului profesorului B.Z. Perlin, Chişinău, 20-22 septembrie 2012Abstract Hypothesis: The morphology of middle ear ossicles varies between people living in different climatic regions. Background: The differences between climatic conditions in different world regions have a morphological and physiological influence on human development. The present study is aimed to investigate morphological variations of middle-ear ossicles collected from different geographic locations on the globe. Methods: Middle ear ossicles (total samples 631) were collected from 6 different geographic regions: Australia, Chile, France, India, Israel and Kenya. Latitude and longitude, and climatic parameters (mean temperature, humidity and daylight duration of the warmer and colder months, and altitude above sea level) were collected for each region. The associations between middle ear ossicles’ dimensions and climate were evaluated using Pearson’s correlations. Results: Significant differences between samples of middle ear ossicles’ characteristics were found. Correlations between the ‘above sea level’ altitude and longitudinal sizes of the malleus, incus and stapes were negative. Correlations between warm temperature and longitudinal sizes of the malleus, incus and stapes were positive. Conclusions: Differences in characteristics of middle ear ossicles encountered between territorial samples could be the result of climatic variations. Гипотеза: морфология косточек среднего уха отличается у людей, живущих в различных климатических районах. Справочная информация: различия климатических условий в различных регионах мира имеют морфологические и физиологические воздействие на развитие человека. Данное исследование направлено на исследование морфологических изменений косточек среднего уха, собранных в различных географических точках земного шара. Методы: косточки среднего уха (всего 631 образец) были собраны в 6 различных географических регионах: Австралия, Чили, Франция, Индия, Израиль и Кения. Широта и долгота, климатические параметры (средняя температура, влажность и продолжительность светового дня теплых и холодных месяцев, высота над уровнем моря) были определены для каждого региона. Связь между размерами косточек среднего уха и климатом были оценены с использованием корреляции Пирсона. Результат: были найдены значительные различия в характеристиках образцов косточек среднего уха. Корреляция между «над уровнем моря» и продольными размерами молоточка, наковальни и стремечка были обратнопропорциональными. Корреляция между теплой температурой и продольными размерами слуховых косточек были прямопропорциональными. Выводы: Различия в характеристиках косточек среднего уха различных территориальных образцов могут быть результатом климатических изменений

    Annealing of amorphous FexCo100-x nanoparticles synthesized by a modified aqueous reduction using NaBH4

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    FexCo100−x nanoparticles were synthesized by aqueous reduction in iron (II) sulfate and cobalt (II) sulfate using sodium borohydride and sodium citrate. The initial concentrations of iron and cobalt were varied while maintaining an overall metal concentration of 4.60 mM. Increasing the cobalt content from 0 to 100 at. % decreased the magnetization saturation from 152 to 48 emu/g, as determined by room temperature vibrating sample magnetometry. Annealing the samples at 450 and 600 °C showed an increase in crystallite size. Powder x-ray diffraction and transmission electron microscopy was performed to determine the phases and morphology of the materials

    Theory of anyon excitons: Relation to excitons of nu=1/3 and nu=2/3 incompressible liquids

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    Elementary excitations of incompressible quantum liquids (IQL's) are anyons, i.e., quasiparticles carrying fractional charges and obeying fractional statistics. To find out how the properties of these quasiparticles manifest themselves in the optical spectra, we have developed the anyon exciton model (AEM) and compared the results with the finite-size data for excitons of nu=1/3 and nu=2/3 IQL's. The model considers an exciton as a neutral composite consisting of three quasielectrons and a single hole. The AEM works well when the separation between electron and hole confinement planes, h, is larger than the magnetic length l. In the framework of the AEM an exciton possesses momentum k and two internal quantum numbers, one of which can be chosen as the angular momentum, L, of the k=0 state. Existence of the internal degrees of freedom results in the multiple branch energy spectrum, crater-like electron density shape and 120 degrees density correlations for k=0 excitons, and the splitting of the electron shell into bunches for non-zero k excitons. For h larger than 2l the bottom states obey the superselection rule L=3m (m are integers starting from 2), all of them are hard core states. For h nearly 2l there is one-to-one correspondence between the low-energy spectra found for the AEM and the many- electron exciton spectra of the nu=2/3 IQL, whereas some states are absent from the many-electron spectra of the nu=1/3 IQL. We argue that this striking difference in the spectra originates from the different populational statistics of the quasielectrons of charge conjugate IQL's and show that the proper account of the statistical requirements eliminates excessive states from the spectrum. Apparently, this phenomenon is the first manifestation of the exclusion statistics in the anyon bound states.Comment: 26 pages with 9 figures, typos correcte

    Theory of Exciton Recombination from the Magnetically Induced Wigner Crystal

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    We study the theory of itinerant-hole photoluminescence of two-dimensional electron systems in the regime of the magnetically induced Wigner crystal. We show that the exciton recombination transition develops structure related to the presence of the Wigner crystal. The form of this structure depends strongly on the separation dd between the photo-excited hole and the plane of the two-dimensional electron gas. When dd is small compared to the magnetic length, additional peaks appear in the spectrum due to the recombination of exciton states with wavevectors equal to the reciprocal lattice vectors of the crystal. For dd larger than the magnetic length, the exciton becomes strongly confined to an interstitial site of the lattice, and the structure in the spectrum reflects the short-range correlations of the Wigner crystal. We derive expressions for the energies and the radiative lifetimes of the states contributing to photoluminescence, and discuss how the results of our analysis compare with experimental observations.Comment: 10 pages, no figures, uses Revtex and multicol.st

    Hard Instances of the Constrained Discrete Logarithm Problem

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    The discrete logarithm problem (DLP) generalizes to the constrained DLP, where the secret exponent xx belongs to a set known to the attacker. The complexity of generic algorithms for solving the constrained DLP depends on the choice of the set. Motivated by cryptographic applications, we study sets with succinct representation for which the constrained DLP is hard. We draw on earlier results due to Erd\"os et al. and Schnorr, develop geometric tools such as generalized Menelaus' theorem for proving lower bounds on the complexity of the constrained DLP, and construct sets with succinct representation with provable non-trivial lower bounds

    Evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu1x_{1-x}Gdx_{x}O

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    Raman scattering studies as functions of temperature, magnetic field, and Gd-substitution are used to investigate the evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu1x_{1-x}Gdx_{x}O. These studies reveal a greater richness of phase behavior than have been previously observed using transport measurements: a spin-fluctuation-dominated paramagnetic (PM) phase regime for T >> T^{*} >> TC_{C}, a two-phase regime for T << T^{*} in which magnetic polarons develop and coexist with a remnant of the PM phase, and an inhomogeneous ferromagnetic phase regime for T << TC_{C}

    Sexuality and Affection among Elderly German Men and Women in Long-Term Relationships: Results of a Prospective Population-Based Study

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    This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The study was funded by the German Federal Ministry for Families, Senior Citizens, Women and Youth (AZ 314-1722-102/16; AZ 301-1720-295/2), the Ministry for Science, Research and Art Baden-Württemberg, and the University of Rostock (FORUN 989020; 889048)

    Pasteurization Preserves IL-8 in Human Milk

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    Background: Pasteurized donor human milk is an alternative feeding when mothers' own milk is not available for premature infants. The effects of pasteurization on the host defense properties of human milk are unclear. We investigated the effects of Holder pasteurization on concentrations of anti-inflammatory and pro-inflammatory cytokines in human milk.Objective: To compare concentrations of anti-inflammatory and pro-inflammatory cytokines before and after pasteurization of donor human milk.Study Design: A single milk sample was obtained from each of 24 mothers of premature infants in the neonatal intensive care unit by electric breast pump and was stored at −80°C. At the time of pasteurization, milk samples were thawed and divided into two aliquots. The first aliquot was re-stored at −80°C and the second aliquot was heat-treated at 62.5°C for 30 min and then re-stored at −80°C. At the time of batch cytokine analyses samples were thawed rapidly.Results: Most cytokine concentrations declined following pasteurization. The most prevalent cytokine, IL-8, was preserved (89%) following pasteurization. There were no relationships between gestational age, postnatal age of milk collection, duration of milk storage, and the concentrations cytokines.Conclusion: In contrast to most cytokines after pasteurization, IL-8 is preserved or liberated from another compartment. The maintenance of IL-8 in human milk after pasteurization and the loss of anti-inflammatory cytokines following pasteurization, suggests that the effects of inflammatory activity in pasteurized human milk should be evaluated. These data may account, in part, for the lesser protective effect on the host of pasteurized donor human milk compared with mother's own milk

    Theory of Photoluminescence of the ν=1\nu=1 Quantum Hall State: Excitons, Spin-Waves and Spin-Textures

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    We study the theory of intrinsic photoluminescence of two-dimensional electron systems in the vicinity of the ν=1\nu=1 quantum Hall state. We focus predominantly on the recombination of a band of initial ``excitonic states'' that are the low-lying energy states of our model at ν=1\nu=1. It is shown that the recombination of excitonic states can account for recent observations of the polarization-resolved spectra of a high-mobility GaAs quantum well. The asymmetric broadening of the spectral line in the σ\sigma_- polarization is explained to be the result of the ``shake-up'' of spin-waves upon radiative recombination of excitonic states. We derive line shapes for the recombination of excitonic states in the presence of long-range disorder that compare favourably with the experimental observations. We also discuss the stabilities and recombination spectra of other (``charged'') initial states of our model. An additional high-energy line observed in experiment is shown to be consistent with the recombination of a positively-charged state. The recombination spectrum of a negatively-charged initial state, predicted by our model but not observed in the present experiments, is shown to provide a direct measure of the formation energy of the smallest ``charged spin-texture'' of the ν=1\nu=1 state.Comment: 23 pages, 7 postscript figures included. Revtex with epsf.tex and multicol.sty. The revised version contains slightly improved numerical results and a few additional discussions of the result
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