2,363 research outputs found
Congruence schemes
A new category of algebro-geometric objects is defined. This construction is
a vast generalization of existing F1-theories, as it contains the the theory of
monoid schemes on the one hand and classical algebraic theory, e.g.
Grothendieck schemes, on the the other. It also gives a handy description of
Berkovich subdomains and thus contains Berkovich's approach to abstract
skeletons. Further it complements the theory of monoid schemes in view of
number theoretic applications as congruence schemes encode number theoretical
information as opposed to combinatorial data which are seen by monoid schemes
The X10 Flare on 2003 October 29: Triggered by Magnetic Reconnection between Counter-Helical Fluxes?
Vector magnetograms taken at Huairou Solar Observing Station (HSOS) and Mees
Solar Observatory (MSO) reveal that the super active region (AR) NOAA 10486 was
a complex region containing current helicity flux of opposite signs. The main
positive sunspots were dominated by negative helicity fields, while positive
helicity patches persisted both inside and around the main positive sunspots.
Based on a comparison of two days of deduced current helicity density,
pronounced changes were noticed which were associated with the occurrence of an
X10 flare that peaked at 20:49 UT, 2003 October 29. The average current
helicity density (negative) of the main sunspots decreased significantly by
about 50. Accordingly, the helicity densities of counter-helical patches
(positive) were also found to decay by the same proportion or more. In
addition, two hard X-ray (HXR) `footpoints' were observed by the Reuven Ramaty
High Energy Solar Spectroscopic Imager (RHESSI} during the flare in the 50-100
keV energy range. The cores of these two HXR footpoints were adjacent to the
positions of two patches with positive current helicity which disappeared after
the flare. This strongly suggested that the X10 flare on 2003 Oct. 29 resulted
from reconnection between magnetic flux tubes having opposite current helicity.
Finally, the global decrease of current helicity in AR 10486 by ~50% can be
understood as the helicity launched away by the halo coronal mass ejection
(CME) associated with the X10 flare.Comment: Solar Physics, 2007, in pres
A Discrete and Bounded Envy-free Cake Cutting Protocol for Four Agents
We consider the well-studied cake cutting problem in which the goal is to
identify a fair allocation based on a minimal number of queries from the
agents. The problem has attracted considerable attention within various
branches of computer science, mathematics, and economics. Although, the elegant
Selfridge-Conway envy-free protocol for three agents has been known since 1960,
it has been a major open problem for the last fifty years to obtain a bounded
envy-free protocol for more than three agents. We propose a discrete and
bounded envy-free protocol for four agents
High-efficiency, high-power difference-frequency generation of 0.9–1.5 μm light in BBO
An efficient method for generation of high energy pulsed ir light between 0.9 and 1.5 μm is described. The technique uses difference frequency mixing of pulsed, visible dye and Nd:YAG laser light in a 10 mm long BBO crystal. Quantum efficiencies of up to 23% and ir pulse energies up to 4.5 mJ are demonstrated. The low shot-to-shot fluctuations of difference frequency generation in BBO make this technique an attractive alternative to the conventional optical parametric oscillator or Raman shifting methods that are currently used to access this spectral region
A simple environment-dependent overlap potential and Cauchy violation in solid argon
We develop an analytic and environment-dependent interatomic potential for
the overlap repulsion in solid argon, based on an approximate treatment of the
non-orthogonal Tight-Binding theory for the closed-shell systems. The present
model can well reproduce the observed elastic properties of solid argon
including Cauchy violation at high pressures, yet very simple. A useful and
novel analysis is given to show how the elastic properties are related to the
environment-dependence incorporated into a generic pairwise potential. The
present study has a close link to the broad field of computational materials
science, in which the inclusion of environment dependence in short-ranged
repulsive part of a potential model is sometimes crucial in predicting the
elastic properties correctly.Comment: 10 pages, 3 figure
Metabolic syndrome risk factors in overweight, obese, and extremely obese brazilian adolescents
Background: Obesity in infancy and adolescence has acquired epidemic dimensions worldwide and is considered a risk factor for a number of disorders that can manifest at an early age, such as Metabolic Syndrome (MS). in this study, we evaluated overweight, obese, and extremely obese adolescents for the presence of MS, and studied the prevalence of single factors of the syndrome in this population.Methods: A total of 321 adolescents (174 females and 147 males) aged 10 to 16 years, attending the Adolescent Outpatient Clinic of Botucatu School of Medicine, Brazil, between April 2009 and April 2011 were enrolled in this study. Adolescents underwent anthropometric evaluation (weight, height, and abdominal circumference) and Body Mass Index (BMI) was estimated according to age and gender, following Disease Control and Prevention Centers recommendations (CDC, 2000). Blood pressure was measured and individuals with BMI >= 85th percentile were submitted to laboratory evaluation for Total Cholesterol, HDL and LDL Cholesterol, Triglycerides, Fasting Insulinemia, and Fasting Glycemia to identify MS factors, according to the criteria suggested by the International Diabetes Federation. Insulin resistance was calculated by HOMA-IR, Quicki, and Fasting Glycemia/Fasting Insulinemia (FGI).Results and discussion: of the 321 adolescents, 95 (29.6%) were overweight, 129 (40.2%) were obese, and 97 (30.2%) were extremely obese. Around 18% were diagnosed with MS. the most prevalent risk factors were abdominal circumference >= 90th percentile (55%), HDL = 130/85 mm/Hg (21%), Triglycerides >= 150 mg/dL (18.5%), and Fasting Glycemia >= 100 mg/dL (2%). Insulin resistance was observed in 65% of the adolescents.Conclusion: An increased prevalence of overweight and obesity, together with cardiometabolic risk factors such as dyslipidemia and abnormal blood pressure, were observed in adolescents, contributing to the onset of metabolic syndrome at younger ages. Risk factors for MS were more prevalent in females.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)São Paulo State Univ UNESP, Botucatu Sch Med, Dept Pediat, São Paulo, BrazilSão Paulo State Univ UNESP, Botucatu Sch Med, Adolescent Med Course, Post Grad Program Gynecol Obstet & Mastol,Dept Pe, São Paulo, BrazilUniv North Parana, Dept Phys Educ, Curitiba, Parana, BrazilSão Paulo State Univ UNESP, Botucatu Sch Med, Dept Pediat, Clin & Expt Pediat Res Ctr, São Paulo, BrazilSão Paulo State Univ UNESP, Botucatu Sch Med, São Paulo, BrazilSão Paulo State Univ UNESP, Botucatu Sch Med, Dept Stat, São Paulo, BrazilFAPESP: 2011/05991-0Web of Scienc
A note on q-Bernoulli numbers and polynomials
By using p-adic q-integrals, we study the q-Bernoulli numbers and polynomials
of higher order.Comment: 8 page
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