27,961 research outputs found

    Coherent Topological Charge Structure in CPN1CP^{N-1} Models and QCD

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    In an effort to clarify the significance of the recent observation of long-range topological charge coherence in QCD gauge configurations, we study the local topological charge distributions in two-dimensional CPN1CP^{N-1} sigma models, using the overlap Dirac operator to construct the lattice topological charge. We find long-range sign coherence of topological charge along extended one-dimensional structures in two-dimensional spacetime. We discuss the connection between the long range topological structure found in CPN1CP^{N-1} and the observed sign coherence along three-dimensional sheets in four-dimensional QCD gauge configurations. In both cases, coherent regions of topological charge form along membrane-like surfaces of codimension one. We show that the Monte Carlo results, for both two-dimensional and four-dimensional gauge theory, support a view of topological charge fluctuations suggested by Luscher and Witten. In this framework, the observed membranes are associated with boundaries between ``k-vacua,'' characterized by an effective local value of θ\theta which jumps by ±2π\pm 2\pi across the boundary.Comment: 26 page

    Monthly average daily global and diffuse solar radiation based on sunshine duration and clearness index for Brasov, Romania

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    The main objective of this study is to develop single location appropriate models for the estimation of the monthly average daily global and diffuse horizontal solar radiation for Brasov, Romania. The study focuses particularly on models based on the sunshine duration and clearness index. The data used for the calibration of the models were collected during a period of 4 yr, between November 2008 and October 2012, at the Transilvania University of Brasov. The testing and validation of the models was carried out using data from the online SoDa database for Brasov for the year 2005. Different statistical error tests were applied to evaluate the accuracy of the models. The predicted values are also compared with values from three other known models concerning the global and diffuse solar radiation. A new mixed model was developed for the estimation of monthly average daily global horizontal solar radiation. The data processing was performed by means of a real-time interface developed with LabVIEW graphical programming language. The parameters taken into account were the relative sunshine, the clearness index, the extraterrestrial radiation, the latitude and the longitude. The methodology is simple and effective and may be applied for any region. Its effectiveness was proven through comparison with global models

    Gambaran Resiliensi Siswa SMA Yang Beresiko Putus Sekolah Di Masyarakat Pesisir

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    Penelitian ini mengkaji resiliensi siswa SMA yang beresiko putus sekolah di masyarakat pesisir. Hasil menunjukkan bahwa resiliensi siswa SMA yang beresiko putus sekolah di masyarakat pesisir secara umum tergolong sedang sampai tinggi. Penelitian kuantitatif deskriptif ini mendeskripsikan nilai mean, standar deviasi, skor minimum dan skor maksimum dari tujuh aspek yang membentuk resiliensi yaitu: Emotion regulation, Impuls control, Optimism, Causal analysis, Emphaty, Self-efficacy dan Reaching out pada siswa SMA yang beresiko putus sekolah di masyarakat pesisir

    A Case Study of the Application of Lightweight Fill for the Restoration of an Interchange Ramp

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    A highway embankment and a sanitary sewer were constructed in the City of London, Ontario, Canada. During construction, a manhole settled approximately 1.5m. There were signs of rotational movement and slope instability in the interchange ramp embankment itself. These movements were attributed to insufficient removal of a deep deposit of peat beneath the ramp embankment identified in the original site investigation. As part of remedial work, additional peat was removed and replaced with compacted sand. Despite these measures, the manhole continued to settle. Monitoring over a period of 30 months showed that the manhole settled by an additional 260mm. Four alternatives were considered to correct the problem. 1. Repair the sanitary sewer at its present location using the same methods as previously employed (excavate and replace). 2. Relocate the sanitary sewer outside the area of influence of the ramp fill and support it on piles and restore the upper part of the embankment with lightweight fill. 3. Reinforce and support the sewer in its present location with pile foundations. 4. Re-route the sanitary sewer. The final remedial strategy consisted of Alternative No. 2 to reduce the amount of further settlements and instabilities. The case history of this project and application of lightweight fill under the conditions described above are discussed in this paper

    Fcc breathing instability in BaBiO_3 from first principles

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    We present first-principles density-functional calculations using the local density approximation to investigate the structural instability of cubic perovskite BaBiO_3. This material might exhibit charge disproportionation and some evidence thereof has been linked to the appearance of an additional, fourth peak in the experimental IR spectrum. However, our results suggest that the origin of this additional peak can be understood within the picture of a simple structural instability. While the true instability consists of an oxygen-octahedra breathing distortion and a small octahedra rotation, we find that the breathing alone in a fcc-type cell doubling is sufficient to explain the fourth peak in the IR spectrum. Our results show that the oscillator strength of this particular mode is of the same order of magnitude as the other three modes, in agreement with experiment.Comment: submitted to PRB, completely revised version after referee repor

    Comparative Analysis of V-Akt Murine Thymoma Viral Oncogene Homolog 3 (AKT3) Gene between Cow and Buffalo Reveals Substantial Differences for Mastitis

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    AKT3 gene is a constituent of the serine/threonine protein kinase family and plays a crucial role in synthesis of milk fats and cholesterol by regulating activity of the sterol regulatory element binding protein (SREBP). AKT3 is highly conserved in mammals and its expression levels during the lactation periods of cattle are markedly increased. AKT3 is highly expressed in the intestine followed by mammary gland and it is also expressed in immune cells. It is involved in the TLR pathways as effectively as proinflammatory cytokines. The aims of this study were to investigate the sequences differences between buffalo and cow. Our results showed that there were substantial differences between buffalo and cow in some exons and noteworthy differences of the gene size in different regions. We also identified the important consensus sequence motifs, variation in 2000 upstream of ATG, substantial difference in the “3′UTR” region, and miRNA association in the buffalo sequences compared with the cow. In addition, genetic analyses, such as gene structure, phylogenetic tree, position of different motifs, and functional domains, were performed to establish their correlation with other species. This may indicate that a buffalo breed has potential resistance to disease, environment changes, and airborne microorganisms and some good production and reproductive traits

    Excitonic effects on coherent phonon dynamics in single wall carbon nanotubes

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    We discuss how excitons can affect the generation of coherent radial breathing modes in ultrafast spectroscopy of single wall carbon nanotubes. Photoexcited excitons can be localized spatially and give rise to a spatially distributed driving force in real space which involves many phonon wavevectors of the exciton-phonon interaction. The equation of motion for the coherent phonons is modeled phenomenologically by the Klein-Gordon equation, which we solve for the oscillation amplitudes as a function of space and time. By averaging the calculated amplitudes per nanotube length, we obtain time-dependent coherent phonon amplitudes that resemble the homogeneous oscillations that are observed in some pump-probe experiments. We interpret this result to mean that the experiments are only able to see a spatial average of coherent phonon oscillations over the wavelength of light in carbon nanotubes and the microscopic details are averaged out. Our interpretation is justified by calculating the time-dependent absorption spectra resulting from the macroscopic atomic displacements induced by the coherent phonon oscillations. The calculated coherent phonon spectra including excitonic effects show the experimentally observed symmetric peaks at the nanotube transition energies in contrast to the asymmetric peaks that would be obtained if excitonic effects were not included.Comment: submitted to Phys. Rev. B on 7 May 2013, revised on 17 July and 13 August 2013, published 30 August 201

    Voltage control of magnetocrystalline anisotropy in ferromagnetic - semiconductor/piezoelectric hybrid structures

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    We demonstrate dynamic voltage control of the magnetic anisotropy of a (Ga,Mn)As device bonded to a piezoelectric transducer. The application of a uniaxial strain leads to a large reorientation of the magnetic easy axis which is detected by measuring longitudinal and transverse anisotropic magnetoresistance coefficients. Calculations based on the mean-field kinetic-exchange model of (Ga,Mn)As provide microscopic understanding of the measured effect. Electrically induced magnetization switching and detection of unconventional crystalline components of the anisotropic magnetoresistance are presented, illustrating the generic utility of the piezo voltage control to provide new device functionalities and in the research of micromagnetic and magnetotransport phenomena in diluted magnetic semiconductors.Comment: Submitted to Physical Review Letters. Updates version 1 to include a more detailed discussion of the effect of strain on the anisotropic magnetoresistanc
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