2,258 research outputs found

    Structure, Transport and Magnetic properties in La2x_{2x}Sr22x_{2-2x}Co2x_{2x}Ru22x_{2-2x}O6_{6}

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    The perovskite solid solutions of the type La2x_{2x}Sr22x_{2-2x}Co2x_{2x}Ru22x_{2-2x}O6_{6} with 0.25 \leq x \leq 0.75 have been investigated for their structural, magnetic and transport properties. All the compounds crystallize in double perovskite structure. The magnetization measurements indicate a complex magnetic ground state with strong competition between ferromagnetic and antiferromagnetic interactions. Resistivity of the compounds is in confirmation with hopping conduction behaviour though differences are noted especially for xx = 0.4 and 0.6. Most importantly, low field (50Oe) magnetization measurements display negative magnetization during the zero field cooled cycle. X-ray photoelectron spectroscopy measurements indicate presence of Co2+^{2+}/Co3+^{3+} and Ru4+^{4+}/Ru5+^{5+} redox couples in all compositions except xx = 0.5. Presence of magnetic ions like Ru4+^{4+} and Co3+^{3+} gives rise to additional ferromagnetic (Ru-rich) and antiferromagnetic sublattices and also explains the observed negative magnetization.Comment: Accepted for publication in J. Magn. Magn. Mate

    Effect of Hetrovalent substitution at Mn site on the Magnetic and Transport Properties of La0.67_{0.67}Sr0.33_{0.33}MnO3_3

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    Magnetic and transport properties of Ti substituted La0.67_{0.67}Sr0.33_{0.33}MnO3_3 are drastically affected with a change in preparation conditions. Low temperature infra-red absorption measurements reveal that this is perhaps due to inhomogeniety in substitution of Ti4+^{4+} on Mn sites. It is found that, in the high temperature annealed samples, the substitution of Ti supresses the double exchange interaction due to the formation of Mn3+^{3+}-O-Ti4+^{4+} chains. While in the low temperature annealed case substitution of Ti causes formation of isolated ferromagnetic clusters linked to each other by a variable range hopping polaron.Comment: 11 pages, 8 figures, accepted in J. Magn. Magn. Magn. Mate

    Search for solar Kaluza-Klein axions in theories of low-scale quantum gravity

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    We explore the physics potential of a terrestrial detector for observing axionic Kaluza-Klein excitations coming from the Sun within the context of higher-dimensional theories of low-scale quantum gravity. In these theories, the heavier Kaluza-Klein axions are relatively short-lived and may be detected by a coincidental triggering of their two-photon decay mode. Because of the expected high multiplicity of the solar axionic excitations, we find experimental sensitivity to a fundamental Peccei-Quinn axion mass up to 10210^{-2} eV (corresponding to an effective axion-photon coupling gaγγ2.×1012g_{a\gamma \gamma} \approx 2.\times 10^{-12} GeV1^{-1}) in theories with 2 extra dimensions and a fundamental quantum-gravity scale MFM_{\rm F} of order 100 TeV, and up to 3.×1033.\times 10^{-3} eV (corresponding to gaγγ6.×1013g_{a\gamma \gamma} \approx 6.\times 10^{-13} GeV1^{-1}) in theories with 3 extra dimensions and MF=1M_{\rm F}=1 TeV. For comparison, based on recent data obtained from lowest level underground experiments, we derive the experimental limits: gaγγ<2.5×1011g_{a \gamma \gamma} \stackrel{<}{{}_\sim} 2.5\times 10^{-11} GeV1^{-1} and gaγγ<1.2×1011g_{a \gamma \gamma} \stackrel{<}{{}_\sim} 1.2\times 10^{-11} GeV1^{-1} in the aforementioned theories with 2 and 3 large compact dimensions, respectively.Comment: 19 pages, extended version, as to appear in Physical Review

    Neutrinos in 5D SO(10) Unification

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    We study neutrino physics in a 5D supersymmetric SO(10) GUT. We analyze several different choices for realizing the See-Saw mechanism. We find that the "natural" scale for the Majorana mass of right-handed neutrinos depends critically on whether the right-handed neutrinos are located in the bulk or localized on a brane. In the former case, the effective Majorana mass is "naturally" of order the compactification scale, about 10^{14} GeV. Note, this is the value necessary for obtaining a light tau neutrino mass approximately 10^{-2} eV which, within the context of hierarchical neutrino masses, is the right order of magnitude to explain atmospheric neutrino oscillations. On the other-hand when the right-handed neutrino is localized on the brane, the effective Majorana mass is typically larger than the compactification scale. Nevertheless with small parameters of order 1/10 - 1/30, an effective Majorana mass of order 10^{14} GeV can be accommodated. We also discuss the constraints on model building resulting from the different scenarios for locating the right-handed neutrinos.Comment: 24 page

    Revised international notation for latex harvest technology

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    Tapping notation that was revised by Lukman in 1983 is revised again. Raingruarding and gaseous stimulation have been incorporated as new items. For tapping period of less than a year, it is shonrn exactly from starting month to ending month. Number of tappings realized against the possible maximum number of tapping days is shornm as a fraction. Similarly actual number of stimulations given against the scheduled number is also shoum as a fraction. Changes have been brought about in the expressions for cut lengrth and frequency of tapping. Use of arrows for expressing directions of tapping cuts and for change of tapping have been changed to more convenient ones. The terminologry, 'exploitation technology' is changed to 'latex harvest technologry'. (Résumé d'auteur

    Enhanced Luminescence of InGaN / GaN Vertical Light Emitting Diodes with an InGaN Protection Layer

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    We have investigated the effectiveness of a thin n-In0.2Ga0.8N layer inserted in the bottom n-GaN layer of InGaN/GaN blue light emitting diodes (LEDs) for the protection of multiple quantum wells during the laser lift-off process for vertical LED fabrication. The photoluminescence properties of the InGaN/GaN lateral LEDs are nearly identical irrespective of the existence of the n-In0.2Ga0.8N insertion layer in the bottom n-GaN layer. However, such an insertion is found to effectively increase the photoluminescence intensity of the multiple quantum well and the carrier lifetime of the vertical LEDs. These improvements are attributed to the reduced defect generations in the vertical LEDs during the laser lift-off process due to the presence of the protection layer. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3521

    Long-term trends in tropical cyclone tracks around Korea and Japan in late summer and early fall

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    This study investigates long-term trends in tropical cyclones (TCs) over the extratropical western North Pacific (WNP) over a period of 35 years (1982-2016). The area analyzed extended across 30-45 degrees N and 120-150 degrees E, including the regions of Korea and Japan that were seriously affected by TCs. The northward migration of TCs over the WNP to the mid-latitudes showed a sharp increase in early fall. In addition, the duration of TCs over the WNP that migrated northwards showed an increase, specifically in early to mid-September. Therefore, more recently, TC tracks have been observed to significantly extend into the mid-latitudes. The recent northward extension of TC tracks over the WNP in early fall was observed to be associated with changes in environmental conditions that were favorable for TC activities, including an increase in sea surface temperature (SST), decrease in vertical wind shear, expansion of subtropical highs, strong easterly steering winds, and an increase in relative vorticity. In contrast, northward migrations of TCs to Korea and Japan showed a decline in late August, because of the presence of unfavorable environmental conditions for TC activities. These changes in environmental conditions, such as SST and vertical wind shear, can be partially associated with the Pacific decadal oscillation

    Quintessence from Shape Moduli

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    We show that shape moduli in sub-millimeter extra dimensional scenarios, addressing the gauge hierarchy problem, can dominate the energy density of the universe today. In our scenario, the volume of the extra dimensions is stabilized at a sufficiently high scale to avoid conflicts with nucleosynthesis and solar-system precision gravity experiments, while the shape moduli remain light but couple extremely weakly to brane-localized matter and easily avoid these bounds. Nonlocal effects in the bulk of the extra dimension generate a potential for the shape moduli. The potential has the right form and order of magnitude to account for the present day cosmic acceleration, in a way analogous to models of quintessence as a pseudo Nambu-Goldstone boson.Comment: 8 pages, 1 figur

    Functional chromatin features are associated with structural mutations in cancer.

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    BACKGROUND: Structural mutations (SMs) play a major role in cancer development. In some cancers, such as breast and ovarian, DNA double-strand breaks (DSBs) occur more frequently in transcribed regions, while in other cancer types such as prostate, there is a consistent depletion of breakpoints in transcribed regions. Despite such regularity, little is understood about the mechanisms driving these effects. A few works have suggested that protein binding may be relevant, e.g. in studies of androgen receptor binding and active chromatin in specific cell types. We hypothesized that this behavior might be general, i.e. that correlation between protein-DNA binding (and open chromatin) and breakpoint locations is common across divergent cancers. RESULTS: We investigated this hypothesis by comprehensively analyzing the relationship among 457 ENCODE protein binding ChIP-seq experiments, 125 DnaseI and 24 FAIRE experiments, and 14,600 SMs from 8 diverse cancer datasets covering 147 samples. In most cancers, including breast and ovarian, we found enrichment of protein binding and open chromatin in the vicinity of SM breakpoints at distances up to 200 kb. Furthermore, for all cancer types we observed an enhanced enrichment in regions distant from genes when compared to regions proximal to genes, suggesting that the SM-induction mechanism is independent from the bias of DSBs to occur near transcribed regions. We also observed a stronger effect for sites with more than one protein bound. CONCLUSIONS: Protein binding and open chromatin state are associated with nearby SM breakpoints in many cancer datasets. These observations suggest a consistent mechanism underlying SM locations across different cancers

    The movement advantage in famous and unfamiliar faces: a comparison of point-light displays and shape-normalised avatar stimuli.

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    Facial movement may provide cues to identity, by supporting the extraction of face shape information via structure-from-motion, or via characteristic patterns of movement. Currently, it is unclear whether familiar and unfamiliar faces derive the same benefit from these mechanisms. This study examined the movement advantage by asking participants to match moving and static images of famous and unfamiliar faces to facial point-light displays (PLDs) or shape-normalised avatars in a same/different task (experiment 1). In experiment 2 we also used a same/different task, but participants matched from PLD to PLD or from avatar to avatar. In both experiments, unfamiliar face matching was more accurate for PLDs than for avatars, but there was no effect of stimulus type on famous faces. In experiment 1, there was no movement advantage, but in experiment 2, there was a significant movement advantage for famous and unfamiliar faces. There was no evidence that familiarity increased the movement advantage. For unfamiliar faces, results suggest that participants were relying on characteristic movement patterns to match the faces, and did not derive any extra benefit from the structure-from-motion cues in the PLDs. The results indicate that participants may use static and movement-based cues in a flexible manner when matching famous and unfamiliar faces
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