1,950 research outputs found

    Distinct order of Gd 4f and Fe 3d moments coexisting in GdFe4Al8

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    Single crystals of flux-grown tetragonal GdFe4Al8 were characterized by thermodynamic, transport, and x-ray resonant magnetic scattering measurements. In addition to antiferromagnetic order at TN ~ 155 K, two low-temperature transitions at T1 ~ 21 K and T2 ~ 27 K were identified. The Fe moments order at TN with an incommensurate propagation vector (tau,tau,0) with tau varying between 0.06 and 0.14 as a function of temperature, and maintain this order over the entire T<TN range. The Gd 4f moments order below T2 with a ferromagnetic component mainly out of plane. Below T1, the ferromagnetic components are confined to the crystallographic plane. Remarkably, at low temperatures the Fe moments maintain the same modulation as at high temperatures, but the Gd 4f moments apparently do not follow this modulation. The magnetic phase diagrams for fields applied in [110] and [001] direction are presented and possible magnetic structures are discussed.Comment: v2: 14 pages, 12 figures; PRB in prin

    Stabilization Control of the Differential Mobile Robot Using Lyapunov Function and Extended Kalman Filter

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    This paper presents the design of a control model to navigate the differential mobile robot to reach the desired destination from an arbitrary initial pose. The designed model is divided into two stages: the state estimation and the stabilization control. In the state estimation, an extended Kalman filter is employed to optimally combine the information from the system dynamics and measurements. Two Lyapunov functions are constructed that allow a hybrid feedback control law to execute the robot movements. The asymptotical stability and robustness of the closed loop system are assured. Simulations and experiments are carried out to validate the effectiveness and applicability of the proposed approach.Comment: arXiv admin note: text overlap with arXiv:1611.07112, arXiv:1611.0711

    Efficiently Clustering Very Large Attributed Graphs

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    Attributed graphs model real networks by enriching their nodes with attributes accounting for properties. Several techniques have been proposed for partitioning these graphs into clusters that are homogeneous with respect to both semantic attributes and to the structure of the graph. However, time and space complexities of state of the art algorithms limit their scalability to medium-sized graphs. We propose SToC (for Semantic-Topological Clustering), a fast and scalable algorithm for partitioning large attributed graphs. The approach is robust, being compatible both with categorical and with quantitative attributes, and it is tailorable, allowing the user to weight the semantic and topological components. Further, the approach does not require the user to guess in advance the number of clusters. SToC relies on well known approximation techniques such as bottom-k sketches, traditional graph-theoretic concepts, and a new perspective on the composition of heterogeneous distance measures. Experimental results demonstrate its ability to efficiently compute high-quality partitions of large scale attributed graphs.Comment: This work has been published in ASONAM 2017. This version includes an appendix with validation of our attribute model and distance function, omitted in the converence version for lack of space. Please refer to the published versio

    Maximal LpL^p-regularity for stochastic evolution equations

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    We prove maximal LpL^p-regularity for the stochastic evolution equation \{{aligned} dU(t) + A U(t)\, dt& = F(t,U(t))\,dt + B(t,U(t))\,dW_H(t), \qquad t\in [0,T], U(0) & = u_0, {aligned}. under the assumption that AA is a sectorial operator with a bounded H∞H^\infty-calculus of angle less than 12π\frac12\pi on a space Lq(O,μ)L^q(\mathcal{O},\mu). The driving process WHW_H is a cylindrical Brownian motion in an abstract Hilbert space HH. For p∈(2,∞)p\in (2,\infty) and q∈[2,∞)q\in [2,\infty) and initial conditions u0u_0 in the real interpolation space \XAp we prove existence of unique strong solution with trajectories in L^p(0,T;\Dom(A))\cap C([0,T];\XAp), provided the non-linearities F:[0,T]\times \Dom(A)\to L^q(\mathcal{O},\mu) and B:[0,T]\times \Dom(A) \to \g(H,\Dom(A^{\frac12})) are of linear growth and Lipschitz continuous in their second variables with small enough Lipschitz constants. Extensions to the case where AA is an adapted operator-valued process are considered as well. Various applications to stochastic partial differential equations are worked out in detail. These include higher-order and time-dependent parabolic equations and the Navier-Stokes equation on a smooth bounded domain \OO\subseteq \R^d with d≥2d\ge 2. For the latter, the existence of a unique strong local solution with values in (H^{1,q}(\OO))^d is shown.Comment: Accepted for publication in SIAM Journal on Mathematical Analysi

    The Taurus Boundary of Stellar/Substellar (TBOSS) Survey II. Disk Masses from ALMA Continuum Observations

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    We report 885μ\mum ALMA continuum flux densities for 24 Taurus members spanning the stellar/substellar boundary, with spectral types from M4 to M7.75. Of the 24 systems, 22 are detected at levels ranging from 1.0-55.6 mJy. The two non-detections are transition disks, though other transition disks in the sample are detected. Converting ALMA continuum measurements to masses using standard scaling laws and radiative transfer modeling yields dust mass estimates ranging from ∼\sim0.3-20M⊕_{\oplus}. The dust mass shows a declining trend with central object mass when combined with results from submillimeter surveys of more massive Taurus members. The substellar disks appear as part of a continuous sequence and not a distinct population. Compared to older Upper Sco members with similar masses across the substellar limit, the Taurus disks are brighter and more massive. Both Taurus and Upper Sco populations are consistent with an approximately linear relationship in MdustM_{dust} to MstarM_{star}, although derived power-law slopes depend strongly upon choices of stellar evolutionary model and dust temperature relation. The median disk around early M-stars in Taurus contains a comparable amount of mass in small solids as the average amount of heavy elements in Kepler planetary systems on short-period orbits around M-dwarf stars, with an order of magnitude spread in disk dust mass about the median value. Assuming a gas:dust ratio of 100:1, only a small number of low-mass stars and brown dwarfs have a total disk mass amenable to giant planet formation, consistent with the low frequency of giant planets orbiting M-dwarfs.Comment: 41 pages and 32 figures, with all tables and appendices presented here in their entirety. Accepted for publication in AJ (November 26, 2017

    The XIIIth Banff Conference on Allograft Pathology: The Banff 2015 Heart Meeting Report: Improving Antibody-Mediated Rejection Diagnostics: Strengths, Unmet Needs, and Future Directions.

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    The 13th Banff Conference on Allograft Pathology was held in Vancouver, British Columbia, Canada from October 5 to 10, 2015. The cardiac session was devoted to current diagnostic issues in heart transplantation with a focus on antibody-mediated rejection (AMR) and small vessel arteriopathy. Specific topics included the strengths and limitations of the current rejection grading system, the central role of microvascular injury in AMR and approaches to semiquantitative assessment of histopathologic and immunophenotypic indicators, the role of AMR in the development of cardiac allograft vasculopathy, the important role of serologic antibody detection in the management of transplant recipients, and the potential application of new molecular approaches to the elucidation of the pathophysiology of AMR and potential for improving the current diagnostic system. Herein we summarize the key points from the presentations, the comprehensive, open and wide-ranging multidisciplinary discussion that was generated, and considerations for future endeavors

    Low dietary intakes of essential nutrients during pregnancy in Vietnam

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    Inadequate intake of nutrients during pregnancy has been associated with poor pregnancy and infant outcomes; however, evidence remains limited in low-resource settings in Asia. This paper assessed food, macronutrient, and micronutrient intakes among 1944 Vietnamese pregnant women. Dietary information was collected via an interviewer-administered food frequency questionnaire, and nutrient intakes were estimated using the Vietnamese food composition tables. The levels of nutrient intakes were evaluated against the Vietnamese recommended nutrient intakes (RNI) for pregnancy. The diet profiles were reported as means and percentages. The average daily food intakes across socio-demographic factors were compared using ANOVA, with adjustment for multiple comparisons by the Tukey–Kramer test. Rice, fruits, and vegetables were the main food sources consumed. The mean energy intake was 2004 kcal/day with 15.9%, 31.8%, and 52.2% of energy deriving from proteins, fats, and carbohydrates, respectively. Just over half of the women did not meet the RNI for total energy intake. The intakes of essential micronutrients including folate, calcium, iron, and zinc were below the RNI, and almost all pregnant women failed to meet the recommendations for these micronutrients. The associations of maternal age, education, and pre-pregnancy body mass index with nutrient intakes varied across the nutrient subgroups. Targeted programs are needed to improve nutrient intakes in Vietnamese pregnant women

    SUSY GUTs contributions and model independent extractions of CP phases

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    We consider the origin of new phases in supersymmetric grand unification model, and show how significant new contributions arise from the gluino mediated diagram. We then present a more general model independent analysis of various modes of B-decays suggested previously for measurement of the CKM phases and point out what they really measure. It is in principle possible to separate out all the phases.Comment: 13 pages (Latex), 2 PS figures, a few remarks are added and a typo is corrected. To appear in Phys. Rev. Let

    Intermediate scale as a source of lepton flavor violation in SUSY SO(10)

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    In supersymmetric SO(10) grand unified models, we examine the lepton flavor violation process μ→eγ\mu \rightarrow e\gamma from having the SU(2)R×_R\times U(1)B−L_{B-L} gauge symmetry broken at an intermediate scale MIM_I below the SO(10) grand unification scale MGM_G. Even in the case that supersymmetry is broken by universal soft terms introduced at the scale MGM_G, we find significant rates for μ→eγ\mu\rightarrow e\gamma with MI∼1012M_I \sim 10^{12} GeV or less. These rates are further enhanced if the universal soft terms appear at a scale greater than MGM_G.Comment: 12 pages (Latex), 3 PS Figures (uuencoded, epsf.tex), small addition to discussion in the text, as to appear in Phys. Rev. D Rapid Communication
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