2,971 research outputs found
Rigorous Probabilistic Analysis of Equilibrium Crystal Shapes
The rigorous microscopic theory of equilibrium crystal shapes has made
enormous progress during the last decade. We review here the main results which
have been obtained, both in two and higher dimensions. In particular, we
describe how the phenomenological Wulff and Winterbottom constructions can be
derived from the microscopic description provided by the equilibrium
statistical mechanics of lattice gases. We focus on the main conceptual issues
and describe the central ideas of the existing approaches.Comment: To appear in the March 2000 special issue of Journal of Mathematical
Physics on Probabilistic Methods in Statistical Physic
Hexagons become second if symmetry is broken
Pattern formation on the free surface of a magnetic fluid subjected to a
magnetic field is investigated experimentally. By tilting the magnetic field
the symmetry can be broken in a controllable manner. When increasing the
amplitude of the tilted field, the flat surface gives way to liquid ridges. A
further increase results in a hysteretic transition to a pattern of stretched
hexagons. The instabilities are detected by means of a linear array of magnetic
hall sensors and compared with theoretical predictions.Comment: accepted for publication by Physical Review E/Rapid Communicatio
Current State of Ixodidae Research in Mongolia
Our research presents the Ixodidae-fauna in Mongolia. The current taxonomic state in Mongolia shows 19 Ixodidae taxa extracted in 308 locations from 115 bird and mammal species. In 1980, the species Ixodes persulcatus SCHULZE, 1930 and Ixodes berlesei Birula, 1895 were detected in Inget Tolgoi and Ixodes laguri OLENEV, 1929 on Meriones unguiculatus 10 km southeast of Ulaanbaatar for the first time. In 2000 the species Haemaphysalis concinna Koch, 1844 was detected in the Selenge-river area and Argas (Argas) vulgaris FILIPPOVA, 1961 was detected in the Gobi area. From the collection of M. and A. STUBBE 1 N (Nymphae) Ixodes persulcatus was detected on Microtus sp. at the Minž-gol (river in Khentey) on July 25, 2002
Polarization instabilities in a two-photon laser
We describe the operating characteristics of a new type of quantum oscillator
that is based on a two-photon stimulated emission process. This two-photon
laser consists of spin-polarized and laser-driven K atoms placed in a
high-finesse transverse-mode-degenerate optical resonator, and produces a beam
with a power of 0.2 W at a wavelength of 770 nm. We observe
complex dynamical instabilities of the state of polarization of the two-photon
laser, which are made possible by the atomic Zeeman degeneracy. We conjecture
that the laser could emit polarization-entangled twin beams if this degeneracy
is lifted.Comment: Accepted by Physical Review Letters. REVTeX 4 pages, 4 EPS figure
Modeling and analysis of a deep learning pipeline for cloud based video analytics.
Video analytics systems based on deep learning approaches are becoming the basis of many widespread applications including smart cities to aid people and traffic monitoring. These systems necessitate massive amounts of labeled data and training time to perform fine tuning of hyper-parameters for object classification. We propose a cloud based video analytics system built upon an optimally tuned deep learning model to classify objects from video streams. The tuning of the hyper-parameters including learning rate, momentum, activation function and optimization algorithm is optimized through a mathematical model for efficient analysis of video streams. The system is capable of enhancing its own training data by performing transformations including rotation, flip and skew on the input dataset making it more robust and self-adaptive. The use of in-memory distributed training mechanism rapidly incorporates large number of distinguishing features from the training dataset - enabling the system to perform object classification with least human assistance and external support. The validation of the system is performed by means of an object classification case-study using a dataset of 100GB in size comprising of 88,432 video frames on an 8 node cloud. The extensive experimentation reveals an accuracy and precision of 0.97 and 0.96 respectively after a training of 6.8 hours. The system is scalable, robust to classification errors and can be customized for any real-life situation.N/
Colligative properties of solutions: I. Fixed concentrations
Using the formalism of rigorous statistical mechanics, we study the phenomena
of phase separation and freezing-point depression upon freezing of solutions.
Specifically, we devise an Ising-based model of a solvent-solute system and
show that, in the ensemble with a fixed amount of solute, a macroscopic phase
separation occurs in an interval of values of the chemical potential of the
solvent. The boundaries of the phase separation domain in the phase diagram are
characterized and shown to asymptotically agree with the formulas used in
heuristic analyses of freezing point depression. The limit of infinitesimal
concentrations is described in a subsequent paper.Comment: 28 pages, 1 fig; see also math-ph/0407035 (both to appear in JSP
Effectiveness and safety of the angiotensin II antagonist irbesartan in children with chronic kidney diseases
Background: Studies in adults with chronic kidney diseases demonstrate that the orally available angiotensin II antagonist irbesartan reduces arterial pressure and pathological proteinuria, mostly with an excellent tolerability profile. Little information is available on irbesartan in childhood. Methods: A total of 44 pediatric outpatients with chronic kidney disease (27 male and 17, aged 3.7 to 18 years, median 10 years) were given irbesartan once a day during 18 weeks for arterial hypertension (N = 23), proteinuria (N = 8), or both (N = 13). Results: In patients with hypertension, the use of irbesartan 4.1 (3.1-5.3) mg/kg body weight daily (median and interquartile range) was associated with a decrease (P < .005) in arterial pressure by 17 (13-22)/10 (7-12) mm Hg. In patients with overt proteinuria the urinary protein excretion decreased (P < .01) during treatment with irbesartan (2.9 [2.0-4.8] mg/kg body weight) by 52 (0-75) mg/[m2 × h]), whereas plasma albumin increased (P < .05) by 4 (1-5) g/L. The frequency of abdominal pain, constipation, cough, diarrhea, dizziness, edema, fatigue, headache, insomnia, myalgia, orthostasis, and rash was similar before and with irbesartan. Plasma sodium slightly decreased, whereas plasma potassium increased, with irbesartan (P < .01). Conclusions: In pediatric patients with chronic kidney diseases, irbesartan given once a day for 18 weeks significantly reduces arterial pressure and proteinuria, with an excellent tolerability and side effect profile. Am J Hypertens 2002;15:1057-1063 © 2002 American Journal of Hypertension, Lt
Instanton approach to the Langevin motion of a particle in a random potential
We develop an instanton approach to the non-equilibrium dynamics in
one-dimensional random environments. The long time behavior is controlled by
rare fluctuations of the disorder potential and, accordingly, by the tail of
the distribution function for the time a particle needs to propagate along the
system (the delay time). The proposed method allows us to find the tail of the
delay time distribution function and delay time moments, providing thus an
exact description of the long-time dynamics. We analyze arbitrary environments
covering different types of glassy dynamics: dynamics in a short-range random
field, creep, and Sinai's motion.Comment: 4 pages, 1 figur
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