802 research outputs found
Влияние глобальных климатических изменений на размеры косточек среднего уха
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
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
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
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 between the photo-excited hole and the plane of the
two-dimensional electron gas. When 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 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
The discrete logarithm problem (DLP) generalizes to the constrained DLP,
where the secret exponent 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 EuGdO
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
EuGdO. 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
T, 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 T
Sexuality and Affection among Elderly German Men and Women in Long-Term Relationships: Results of a Prospective Population-Based Study
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
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 Quantum Hall State: Excitons, Spin-Waves and Spin-Textures
We study the theory of intrinsic photoluminescence of two-dimensional
electron systems in the vicinity of the 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 . 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 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
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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