53 research outputs found
Modular Groups, Visibility Diagram and Quantum Hall Effect
We consider the action of the modular group on the set of
positive rational fractions. From this, we derive a model for a classification
of fractional (as well as integer) Hall states which can be visualized on two
``visibility" diagrams, the first one being associated with even denominator
fractions whereas the second one is linked to odd denominator fractions. We use
this model to predict, among some interesting physical quantities, the relative
ratios of the width of the different transversal resistivity plateaus. A
numerical simulation of the tranversal resistivity plot based on this last
prediction fits well with the present experimental data.Comment: 17 pages, plain TeX, 4 eps figures included (macro epsf.tex), 1
figure available from reques
On multiplicities in length spectra of arithmetic hyperbolic three-orbifolds
Asymptotic laws for mean multiplicities of lengths of closed geodesics in
arithmetic hyperbolic three-orbifolds are derived. The sharpest results are
obtained for non-compact orbifolds associated with the Bianchi groups SL(2,o)
and some congruence subgroups. Similar results hold for cocompact arithmetic
quaternion groups, if a conjecture on the number of gaps in their length
spectra is true. The results related to the groups above give asymptotic lower
bounds for the mean multiplicities in length spectra of arbitrary arithmetic
hyperbolic three-orbifolds. The investigation of these multiplicities is
motivated by their sensitive effect on the eigenvalue spectrum of the
Laplace-Beltrami operator on a hyperbolic orbifold, which may be interpreted as
the Hamiltonian of a three-dimensional quantum system being strongly chaotic in
the classical limit.Comment: 29 pages, uuencoded ps. Revised version, to appear in NONLINEARIT
An Effective Superstring Spectral Action
A supersymmetric theory in two-dimensions has enough data to define a
noncommutative space thus making it possible to use all the tools of
noncommutative geometry. In particular, we apply this to the N=1 supersymmetric
non-linear sigma model and derive an expression for the generalized loop space
Dirac operator, in presence of a general background, using canonical
quantization. The spectral action principle is used to show that the
superstring partition function is also a spectral action valid for the
fluctuations of the string modes.Comment: 31 pages, Latex fil
Trochanteric Femur Fractures: Application of Skeletal Traction during Surgery Does Not Alter Soft-Tissue Microcirculation
Background and Objectives: Wound infections provoked by alterations in microcirculation
are major complications in the treatment of trochanteric femur fractures. Surgical fracture fixation
on a traction table is the gold standard for treatment, but the effect on tissue microcirculation is
unknown. Microcirculation could be impaired by the pull on the soft-tissue or by a release of
vasoactive factors. We hypothesized that intraoperative traction impairs soft-tissue microcirculation.
Materials and Methods: In 22 patients (14 women, eight men), average age 78 years (range 36â96 ± 14),
with trochanteric femur fractures, non-invasive laser-Doppler spectrophotometry was used to assess
oxygen saturation, hemoglobin content, and blood flow in the skin and subcutaneous tissue before
and after application of traction. Measurements were recorded in nine locations around the greater
trochanter at a depth of 2, 8, and 15 mm before and after fracture reduction by traction. Results: No
differences were found in any depth with traction compared to without (oxygen saturation: p = 0.751,
p = 0.308, and p = 0.955, haemoglobin content: p = 0.651, p = 0.928, and p = 0.926, blood flow: p = 0.829,
p = 0.866, and p = 0.411). Conclusion: In this pilot study, the application of traction does not affect skin
and subcutaneous microcirculation in the surgery of proximal femur fractures
The search for transient astrophysical neutrino emission with IceCube-DeepCore
We present the results of a search for astrophysical sources of brief transient neutrino emission using IceCube and DeepCore data acquired between 2012 May 15 and 2013 April 30. While the search methods employed in this analysis are similar to those used in previous IceCube point source searches, the data set being examined consists of a sample of predominantly sub-TeV muon-neutrinos from the Northern Sky (-5 degrees < delta < 90 degrees) obtained through a novel event selection method. This search represents a first attempt by IceCube to identify astrophysical neutrino sources in this relatively unexplored energy range. The reconstructed direction and time of arrival of neutrino events are used to search for any significant self-correlation in the data set. The data revealed no significant source of transient neutrino emission. This result has been used to construct limits at timescales ranging from roughly 1 s to 10 days for generic soft-spectra transients. We also present limits on a specific model of neutrino emission from soft jets in core-collapse supernovae
17ÎČ-estradiol suppresses lipopolysaccharide-induced acute lung injury through PI3K/Akt/SGK1 mediated up-regulation of epithelial sodium channel (ENaC) in vivo and in vitro
Neuroprotective and neurodegenerative effects of the chronic expression of tumor necrosis factor α in the nigrostriatal dopaminergic circuit of adult mice
Do male and female trauma patients receive the same prehospital care?: an observational follow-up study
does participating in national and ethnic associations promote migrant integration a study with young first and second generation migrants
On arrival to a new country, migrants usually face language barriers, cultural barriers, discrimination, and other sources of unjust contextual conditions that lower their chances of a successful life (Handy and Greenspan, Nonprofit Volunt Sect Q 38:956â982, 2009). This scenario compromises their levels of well-being and supports a tendency toward social fragmentation in places of settlement (Garcia-Ramirez et al., Am J Community Psychol 47(1â2), 86â97, 2011). In response to this situation, migrants' engagement in civic life has been identified as an important element for developing both individual well-being and cohesive communities (Gilster, J Community Psychol 40(7), 769â784, 2012) (Stoll and Wong, Int Migr Rev 41(4), 880â908, 2007). Using a qualitative study, the present work explores the effects of activism on youth of sub-Saharan African origin, of the first and second generations, who are active in national and ethnic associations. The work aims to explore (1) through narratives the meaning that integration has for young migrants; (2) how integrated they feel; and (3) the role of the association, both national and ethnic, in the perception of integration of these young people
Lost in Time
This graduate text for courses in career counseling is distinguished by its emphasis on creative interventions tailored to the unique needs of diverse populations. With a focus on career as a cornerstone of personal identity, the book explores the specific meaning of careers within different cultures and examines the challenges faced by, and potential solutions for, individuals with diverse backgrounds and needs. It describes unique interventions that allow counseling students to visualize and actualize career counseling with a wide range of clients and demonstrates techniques targeted to each population that can be put into practice immediately
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