3,704 research outputs found

    Shaking-induced dynamics of cold atoms in magnetic traps

    Get PDF
    We describe an experiment in which cold rubidium atoms, confined in an elongated magnetic trap, are excited by transverse oscillation of the trap center. The temperature after excitation exhibits resonance as a function of the driving frequency. We measure these resonances at several different trap frequencies. In order to interpret the experiments, we develop a simple model that incorporates both collisions between atoms and the anharmonicity of the real three-dimensional trapping potential. As well as providing a precise connection between the transverse harmonic oscillation frequency and the temperature resonance frequency, this model gives insight into the heating and loss mechanisms and into the dynamics of driven clouds of cold trapped atoms

    Analytical, numerical, and experimental analysis of inverse macrosegregation during upward unidirectional solidification of Al-Cu alloys

    Get PDF
    The present work focuses on the influence of alloy solute content, melt superheat, and metal/mold heat transfer on inverse segregation during upward solidification of Al-Cu alloys. The experimental segregation profiles of Al 4.5 wt pet Cu, 6.2 wt pet Cu, and 8.1 wt pet Cu alloys are compared with theoretical predictions furnished by analytical and numerical models, with transient h(i) profiles being determined in each experiment. The analytical model is based on an analytical heat-transfer model coupled with the classical local solute redistribution equation proposed by Flemings and Nereo. The numerical model is that proposed by Voller, with some changes introduced to take into account different thermophysical properties for the liquid and solid phases, time variable metal/mold interface heat-transfer coefficient, and a variable space grid to assure the accuracy of results without raising the number of nodes. It was observed that the numerical predictions generally conform with the experimental segregation measurements and that the predicted analytical segregation, despite its simplicity, also compares favorably with the experimental scatter except for high melt superheat.35228529

    Combinatorial RNA Design: Designability and Structure-Approximating Algorithm

    Get PDF
    In this work, we consider the Combinatorial RNA Design problem, a minimal instance of the RNA design problem which aims at finding a sequence that admits a given target as its unique base pair maximizing structure. We provide complete characterizations for the structures that can be designed using restricted alphabets. Under a classic four-letter alphabet, we provide a complete characterization of designable structures without unpaired bases. When unpaired bases are allowed, we provide partial characterizations for classes of designable/undesignable structures, and show that the class of designable structures is closed under the stutter operation. Membership of a given structure to any of the classes can be tested in linear time and, for positive instances, a solution can be found in linear time. Finally, we consider a structure-approximating version of the problem that allows to extend bands (helices) and, assuming that the input structure avoids two motifs, we provide a linear-time algorithm that produces a designable structure with at most twice more base pairs than the input structure.Comment: CPM - 26th Annual Symposium on Combinatorial Pattern Matching, Jun 2015, Ischia Island, Italy. LNCS, 201

    Aseptic Meningitis in Kikuchi's Disease

    Get PDF
    The involvement of the nervous system in Kikuchi's disease (KD) is rare. Although some reports of meningeal involvement in KD were described in the literature from Japan, it has rarely been reported in Korea. A 23-year-old man presented with severe headache, fever, and vomiting. Cerebrospinal fluid (CSF) analysis revealed an opening pressure 300 mmH2O, WBC 283/mm3, glucose 44 mg/dl and protein 86 mg/dl. Multiple tender lymph nodes on the left anterior neck were found on the 9th day of his hospital stay. The lymph node biopsy disclosed histopathologic features typical of KD. We report a patient with KD accompanied by aseptic meningitis, emphasizing the importance of recognizing this disorder in diagnosing patients with meningitis

    Effect of light-curing units on the thermal expansion of resin nanocomposites

    Get PDF
    Purpose—To examine the thermal expansion of resin nanocomposites after light-curing using different light-curing units. Methods—Four different resin nanocomposites and four different light-curing units [quartztungsten- halogen (QTH), light emitting diode (LED), laser, and plasma arc] were chosen. Metal dies were filled with resin to make specimens and light-cured. The light intensity and light-curing time of the QTH and LED light-curing units were 1000 mW/cm2 and 40 seconds, 700 mW/cm2 and 40 seconds for the laser, and 1600 mW/cm2 and 3 seconds for the plasma arc. The coefficient of thermal expansion (CTE) was evaluated using a thermomechanical analyzer (TMA) at temperatures ranging from 30–80°C. Results—The CTE of the resin nanocomposites tested ranged from 28.5 to 65.8 (×10−6/°C), depending on the product and type of light-curing unit used. Among the specimens Grandio showed the lowest CTE. The specimens cured using the plasma arc unit (Apollo 95E) showed the highest CTE. There was a linear correlation between the CTE and filler content (vol%) (R: −0.94~ −0.99 depending on the light-curing unit). The results may suggest a careful selection of the lightcuring unit because there was more expansion in the specimens cured using the plasma arc unit than those cured by the other units. (Am J Dent 2010;23:331–334)

    Thermodynamic analysis of black hole solutions in gravitating nonlinear electrodynamics

    Full text link
    We perform a general study of the thermodynamic properties of static electrically charged black hole solutions of nonlinear electrodynamics minimally coupled to gravitation in three space dimensions. The Lagrangian densities governing the dynamics of these models in flat space are defined as arbitrary functions of the gauge field invariants, constrained by some requirements for physical admissibility. The exhaustive classification of these theories in flat space, in terms of the behaviour of the Lagrangian densities in vacuum and on the boundary of their domain of definition, defines twelve families of admissible models. When these models are coupled to gravity, the flat space classification leads to a complete characterization of the associated sets of gravitating electrostatic spherically symmetric solutions by their central and asymptotic behaviours. We focus on nine of these families, which support asymptotically Schwarzschild-like black hole configurations, for which the thermodynamic analysis is possible and pertinent. In this way, the thermodynamic laws are extended to the sets of black hole solutions of these families, for which the generic behaviours of the relevant state variables are classified and thoroughly analyzed in terms of the aforementioned boundary properties of the Lagrangians. Moreover, we find universal scaling laws (which hold and are the same for all the black hole solutions of models belonging to any of the nine families) running the thermodynamic variables with the electric charge and the horizon radius. These scale transformations form a one-parameter multiplicative group, leading to universal "renormalization group"-like first-order differential equations. The beams of characteristics of these equations generate the full set of black hole states associated to any of these gravitating nonlinear electrodynamics...Comment: 51 single column pages, 19 postscript figures, 2 tables, GRG tex style; minor corrections added; final version appearing in General Relativity and Gravitatio

    Effect of staining solutions on discoloration of resin nanocomposites

    Get PDF
    Purpose—To examine the effect of staining solutions on the discoloration of resin nanocomposites. Methods—Three resin nanocomposites (Ceram X, Grandio, and Filtek Z350) were light cured for 40 seconds at a light intensity of 1000 mW/cm2. The color of the specimens was measured in %R (reflectance) mode before and after immersing the specimens in four different test solutions [distilled water (DW), coffee (CF), 50% ethanol (50ET) and brewed green tea (GT)] for 7 hours/ day over a 3-week period. The color difference (ΔE*) was obtained based on the CIEL*a*b* color coordinate values. Results—The specimens immersed in DW, 50ET and GT showed a slight increase in L* value. However, the samples immersed in CF showed a decrease in the L* value and an increase in the b* value. CF induced a significant color change (ΔE*: 3.1~5.6) in most specimens but the other solutions induced only a slight color change. Overall, coffee caused unacceptable color changes to the resin nanocomposites

    Warfarin-Induced Eosinophilic Pleural Effusion

    Get PDF
    A 29-year-old man suffering from dyspnea and eosinophilic pleural effusion after being on warfarin for pulmonary thromboembolism for a period of one month, was readmitted to our hospital. Etiology of pleural effusion other than warfarin was excluded. To the best of our knowledge, this is the first case of warfarin-induced pleural effusion reported in Korea

    Enhanced spin-phonon-electronic coupling in a 5d oxide

    Get PDF
    Enhanced coupling of material properties offers new fundamental insights and routes to multifunctional devices. In this context 5d oxides provide new paradigms of cooperative interactions that drive novel emergent behaviour. This is exemplified in osmates that host metal-insulator transitions where magnetic order appears intimately entwined. Here we consider such a material, the 5d perovskite NaOsO3, and observe a coupling between spin and phonon manifested in a frequency shift of 40 cm(-1), the largest measured in any material. The anomalous modes are shown to involve solely Os-O interactions and magnetism is revealed as the driving microscopic mechanism for the phonon renormalization. The magnitude of the coupling in NaOsO3 is primarily due to a property common to all 5d materials: the large spatial extent of the ion. This allows magnetism to couple to phonons on an unprecedented scale and in general offers multiple new routes to enhanced coupled phenomena in 5d materials.open0

    Assessment of plaque evolution in coronary bifurcations located beyond everolimus eluting scaffolds: Serial intravascular ultrasound virtual histology study

    Get PDF
    Purpose. To evaluate the atherosclerotic evolution in coronary bifurcations located proximally and distally to a bioresorbable scaffold. Methods. Thirty bifurcations located >5 mm beyond the scaffolded segment, being investigated with serial intravascular ultrasound virtual histology (IVUS-VH) examinations, at baseline and 2-years, in patients enrolled in the ABSORB cohort B1 study were included in this analysis. In each bifurcation, the frames portraying the proximal rim, in-bifurcation, and distal rim of the ostium of the side branch were analyzed. The geometric parameters and plaque types were evaluated at baseline and 2-years follow-up. Results: There were no significant differences in the geometrical parameters such as lumen, vessel and plaque areas as well as in the composition of the atheroma between baseline and 2-years follow-up.When we separately examined the bifurcations located proximally and distally to the scaffolded segment, no changes were found at the distal bifurcations, while at the proximal bifurcations there was a statistical significant decrease in the plaque burden (36.67 ± 13.33% at baseline vs. 35.06 ± 13.20% at 2 years follow-up, p = 0.04).Ten necrotic core rich plaques were found at baseline, of which 2 regressed to either fibrotic plaque or to intimal thickening at 2 years follow-up. The other 8 did not change. Disease progression was noted in 3 plaques (1 adaptive intimal thickening, 1 fibrotic and 1 fibroca
    • 

    corecore