3,542 research outputs found

    The Steward Observatory asteroid relational database

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    The Steward Observatory Asteroid Relational Database (SOARD) was created as a flexible tool for undertaking studies of asteroid populations and sub-populations, to probe the biases intrinsic to asteroid databases, to ascertain the completeness of data pertaining to specific problems, to aid in the development of observational programs, and to develop pedagogical materials. To date SOARD has compiled an extensive list of data available on asteroids and made it accessible through a single menu-driven database program. Users may obtain tailored lists of asteroid properties for any subset of asteroids or output files which are suitable for plotting spectral data on individual asteroids. A browse capability allows the user to explore the contents of any data file. SOARD offers, also, an asteroid bibliography containing about 13,000 references. The program has online help as well as user and programmer documentation manuals. SOARD continues to provide data to fulfill requests by members of the astronomical community and will continue to grow as data is added to the database and new features are added to the program

    Excitation spectrum of bosons in a finite one-dimensional circular waveguide via the Bethe ansatz

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    The exactly solvable Lieb-Liniger model of interacting bosons in one-dimension has attracted renewed interest as current experiments with ultra-cold atoms begin to probe this regime. Here we numerically solve the equations arising from the Bethe ansatz solution for the exact many-body wave function in a finite-size system of up to twenty particles for attractive interactions. We discuss the novel features of the solutions, and how they deviate from the well-known string solutions [H. B. Thacker, Rev. Mod. Phys.\ \textbf{53}, 253 (1981)] at finite densities. We present excited state string solutions in the limit of strong interactions and discuss their physical interpretation, as well as the characteristics of the quantum phase transition that occurs as a function of interaction strength in the mean-field limit. Finally we compare our results to those of exact diagonalization of the many-body Hamiltonian in a truncated basis. We also present excited state solutions and the excitation spectrum for the repulsive 1D Bose gas on a ring.Comment: 13 pages, 12 figure

    Nucleic acid derived indices or instantaneous growth rate as tools to determine different nutricional condition in cuttlefish (Sepia officinalis, linnaeus 1758) hatchlings

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    Two groups of 100 cuttlefish hatchlings each were used to determine the duration of the yolk reserves, during which growth can be obtained with no food supply. One group was fed live grass shrimp ad libitum from the 3rd day of life onwards, while the other was starved during the whole experiment. The experiment lasted 7 days, because this was the 1st day where a negative growth rate was obtained. Nucleic acid derived indices and instantaneous growth rates (IGR) were used as a way to describe their condition, when all the yolk reserves would be exhausted and to determine the most accurate tool to express growth and condition. RNA/DNA ratios described clearly the differences (P 0.05) between groups and did not displayed a clear pattern with increasing age. Correlation between IGR and DNA was only attained for the fed population (R −0.90; P 0.0374). RNA concentration values were different from day 5 onwards. Any of the nucleic acid derived indexes were not accurate enough to express growth and condition, so IGR seems to be the most accurate and inexpensive way to describe hatchlings growth and condition in controlled conditions.info:eu-repo/semantics/publishedVersio

    Spatial nonlocal pair correlations in a repulsive 1D Bose gas

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    We analytically calculate the spatial nonlocal pair correlation function for an interacting uniform 1D Bose gas at finite temperature and propose an experimental method to measure nonlocal correlations. Our results span six different physical realms, including the weakly and strongly interacting regimes. We show explicitly that the characteristic correlation lengths are given by one of four length scales: the thermal de Broglie wavelength, the mean interparticle separation, the healing length, or the phase coherence length. In all regimes, we identify the profound role of interactions and find that under certain conditions the pair correlation may develop a global maximum at a finite interparticle separation due to the competition between repulsive interactions and thermal effects.Comment: Final published version, modified titl

    Looking beyond the physical management of patients with head and neck cancer

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    Cancers of the head and neck region often leave patients with conspicuous defects, as well as limitations in physical and psycho-social functions. Rehabilitation is challenging and can never fully restore the anatomical, physiological, or functional characteristics that have been lost. Ideally newly diagnosed cancer patients should be managed by a multidisciplinary team of specialists from various allied fields who will be able to educate them and help them decide on the most appropriate and suitable treatment options. Patients must understand the processes, be of possible side effects and comprehend the limitations aware of rehabilitation. At the same time, clinicians may need to consider issues of distributive justice when deciding which patients will receive which resources, especially in financially limited institutions and countries. The biggest challenge to us as clinicians as well as community members is to try and treat all patients holistically and to address both their physical and psychosocial needs. This requires a fervent commitment to action, and that we all stand together and help each other through difficult times

    Planetary Science Goals for the Spitzer Warm Era

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    The overarching goal of planetary astronomy is to deduce how the present collection of objects found in our Solar System were formed from the original material present in the proto-solar nebula. As over two hundred exo-planetary systems are now known, and multitudes more are expected, the Solar System represents the closest and best system which we can study, and the only one in which we can clearly resolve individual bodies other than planets. In this White Paper we demonstrate how to use Spitzer Space Telescope InfraRed Array Camera Channels 1 and 2 (3.6 and 4.5 µm) imaging photometry with large dedicated surveys to advance our knowledge of Solar System formation and evolution. There are a number of vital, key projects to be pursued using dedicated large programs that have not been pursued during the five years of Spitzer cold operations. We present a number of the largest and most important projects here; more will certainly be proposed once the warm era has begun, including important observations of newly discovered objects

    Controlling Hydrocarbon (De)Hydrogenation Pathways with Bifunctional PtCu Single-Atom Alloys

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    The conversions of surface-bound alkyl groups to alkanes and alkenes are important steps in many heterogeneously catalyzed reactions. On the one hand, while Pt is ubiquitous in industry because of its high activity toward C-H activation, many Pt-based catalysts tend to overbind reactive intermediates, which leads to deactivation by carbon deposition and coke formation. On the other hand, Cu binds intermediates more weakly than Pt, but activation barriers tend to be higher on Cu. We examine the reactivity of ethyl, the simplest alkyl group that can undergo hydrogenation and dehydrogenation via β-elimination, and show that isolated Pt atoms in Cu enable low-temperature hydrogenation of ethyl, unseen on Cu, while avoiding the decomposition pathways on pure Pt that lead to coking. Furthermore, we confirm the predictions of our theoretical model and experimentally demonstrate that the selectivity of ethyl (de)hydrogenation can be controlled by changing the surface coverage of hydrogen

    Whole blood holding time prior to plasma processing alters microRNA expression profile

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    MicroRNAs (miRNAs) can exhibit aberrant expression under different physiological and pathological conditions. Therefore, differentially expressed circulating miRNAs have been a focus of biomarker discovery research. However, the use of circulating miRNAs comes with challenges which may hinder the reliability for their clinical application. These include varied sample collection protocols, storage times/conditions, sample processing and analysis methods. This study focused on examining the effect of whole blood holding time on the stability of plasma miRNA expression profiles. Whole blood samples were collected from healthy pregnant women and were held at 4°C for 30 min, 2 h, 6 h or 24 h prior to processing for plasma isolation. Plasma RNA was extracted and the expression of 179 miRNAs were analyzed. Unsupervised principal component analysis demonstrated that whole blood holding time was a major source of variation in miRNA expression profiles with 53 of 179 miRNAs showing significant changes in expression. Levels of specific miRNAs previously reported to be associated with pregnancy-associated complications such as hsa-miR-150-5p, hsa-miR-191-5p, and hsa-miR-29a-3p, as well as commonly used endogenous miRNA controls, hsa-miR-16-5p, hsa-miR-25-3p, and hsa-miR-223-3p were significantly altered with increase in blood holding time. Current protocols for plasma-based miRNA profiling for diagnostics describe major differences in whole blood holding periods ranging from immediately after collection to 26 h after. Our results demonstrate holding time can have dramatic effects on analytical reliability and reproducibility. This highlights the importance of standardization of blood holding time prior to processing for plasma in order to minimize introduction of non-biological variance in miRNA profiles

    Complex-Temperature Singularities in the d=2d=2 Ising Model. III. Honeycomb Lattice

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    We study complex-temperature properties of the uniform and staggered susceptibilities χ\chi and χ(a)\chi^{(a)} of the Ising model on the honeycomb lattice. From an analysis of low-temperature series expansions, we find evidence that χ\chi and χ(a)\chi^{(a)} both have divergent singularities at the point z=1zz=-1 \equiv z_{\ell} (where z=e2Kz=e^{-2K}), with exponents γ=γ,a=5/2\gamma_{\ell}'= \gamma_{\ell,a}'=5/2. The critical amplitudes at this singularity are calculated. Using exact results, we extract the behaviour of the magnetisation MM and specific heat CC at complex-temperature singularities. We find that, in addition to its zero at the physical critical point, MM diverges at z=1z=-1 with exponent β=1/4\beta_{\ell}=-1/4, vanishes continuously at z=±iz=\pm i with exponent βs=3/8\beta_s=3/8, and vanishes discontinuously elsewhere along the boundary of the complex-temperature ferromagnetic phase. CC diverges at z=1z=-1 with exponent α=2\alpha_{\ell}'=2 and at v=±i/3v=\pm i/\sqrt{3} (where v=tanhKv = \tanh K) with exponent αe=1\alpha_e=1, and diverges logarithmically at z=±iz=\pm i. We find that the exponent relation α+2β+γ=2\alpha'+2\beta+\gamma'=2 is violated at z=1z=-1; the right-hand side is 4 rather than 2. The connections of these results with complex-temperature properties of the Ising model on the triangular lattice are discussed.Comment: 22 pages, latex, figures appended after the end of the text as a compressed, uuencoded postscript fil
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