15,656 research outputs found

    Proton beam radiotherapy in the management of uveal melanoma: clinical experience in Scotland

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    <p>Aim: To evaluate proton-beam radiotherapy (PBRT) in the management of uveal melanoma in Scotland.</p> <p>Methods: A retrospective review was undertaken on all patients receiving PBRT for uveal melanoma (1994–2005). Data obtained included: gender, past ocular/medical history, age, presenting complaint(s), diagnosis, laterality, tumor location/ultrasound characteristics, visual acuity (VA) and intraocular pressure. At post-treatment reviews (3, 6, 12, and 24 months), the following data was obtained: VA, intraocular pressure, tumor appearance and ultrasound characteristics. Mean follow up was 38.8 months.</p> <p>Results: Seventy-six patients were included. Mean age was 64 years; male to female ratio was 1.1:1. Ninety-seven percent demonstrated initial treatment response; 87% had successful control of tumor growth. Mean pre-treatment tumor height was 6.2 mm v.s. 4.8 mm post-irradiation (p < 0.001). Pre-irradiation VA was <3/60 in 18.5% compared with 74% post-irradiation (p < 0.0001). There was a statistically significant association between adverse events (enucleation, metastasis) and greater maximal basal tumor diameter. Eighteen eyes were enucleated. The median survival time was estimated to be 54 months.</p> <p>Conclusion: In our experience, PBRT is a precise, reliable and effective treatment in the management of large, and previously treated uveal melanomas. It prevents enucleation in the majority at short term follow-up.</p&gt

    Diffusion Monte Carlo study of two-dimensional liquid 4^4He

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    The ground-state properties of two-dimensional liquid 4^4He at zero temperature are studied by means of a quadratic diffusion Monte Carlo method. As interatomic potential we use a revised version of the HFDHE2 Aziz potential which is expected to give a better description of the interaction between helium atoms. The equation of state is determined with great accuracy over a wide range of densities in the liquid phase from the spinodal point up to the freezing density. The spinodal decomposition density is estimated and other properties of the liquid, such as radial distribution function, static form factor, momentum distribution and density dependence of the condensate fraction are all presented.Comment: 19 pages, RevTex 3.0, 7 figures available upon reques

    Jost Function for Singular Potentials

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    An exact method for direct calculation of the Jost function and Jost solutions for a repulsive singular potential is presented. Within this method the Schrodinger equation is replaced by an equivalent system of linear first-order differential equations, which after complex rotation, can easily be solved numerically. The Jost function can be obtained to any desired accuracy for all complex momenta of physical interest, including the spectral points corresponding to bound and resonant states. The method can also be used in the complex angular-momentum plane to calculate the Regge trajectories. The effectiveness of the method is demonstrated using the Lennard-Jones (12,6) potential. The spectral properties of the realistic inter-atomic He4-He4 potentials HFDHE2 and HFD-B of Aziz and collaborators are also investigated.Comment: 12 pages, latex, 2 eps-figures, submitted to Phys.Rev.

    Pertumbuhan Akar Pada Perkecambahan Beberapa Varietas Tomat Dengan Pemberian Polyethylene Glikol (Peg) Secara in Vitro

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    Tomato plants originated from Mexico to Peru region. At the present time the tomato hasbecome more developed, modern cultivars or hybrids can grow well and produce the climate ismuch different from the place of origin. This study aims to create drought tolerant plant of tomatovarieties. The research has done in Tissue Culture Laboratory Fakultuty Agriculture UnivercityNort Sumatera, Medan since Juli-September 2012. Using a completely randomized design with twofactors, that is Polyethylene Glicol (PEG) (0,5,10,15,20%) and Tomato varieties (TO-244, Niki,Kartika, Mio, Super Hawai) with four replications. Observation variable is living root forminginitiation, total of root, and high of roott. The result of research has shown that PEG is significantfor root forming initiation and high of root, but not significant for total of root

    Toxopjasmagondania Jlle and Manceaux Pada Ayam Bukan Ras (Gallus SP.) Dan Burung Merpati (Columba Una Gmelin) Dikotamadya Bogor (Toxoplosma Gondti Nicolle and Monceaux on Domestic Fowl (G&llus Sp.j and Domestic Pigeon (Columba Liua Gmelin) From Kotamadya Bo

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    Using Indirect Hemqiglutination (IHA) test on 26 domesticfowl (Gallus sp.)and domestic pigeon (Columba liviaj were screened "Toxoplasrna gondii infection.All of the serum samples tested were positiffor this protopal infection.From the quantitatif test on 14positives serum samples, 14,28 % has the lowest liter of1£4 and 7,14 % has the highest liter of 1:1024. Mode of the disease spreading and the prevention off.gondii were discussed

    Propositional calculus for adjointness lattices

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    Recently, Morsi has developed a complete syntax for the class of all adjointness algebras (L,,A,K,H)\left( L,\leq ,A,K,H\right) . There, (L,)\left( L,\leq \right) is a partially ordered set with top element 11, KK is a conjunction on (L,)\left( L,\leq \right) for which 11 is a left identity element, and the two implication-like binary operations AA and HH on LL are adjoints of KK. In this paper, we extend that formal system to one for the class ADJLADJL of all 9-tuples (L,,1,0,A,K,H,,)\left( L,\leq ,1,0,A,K,H,\wedge ,\vee \right) , called \emph{% adjointness lattices}; in each of which (L,,1,0,,)\left( L,\leq ,1,0,\wedge ,\vee \right) is a bounded lattice, and (L,,A,K,H)\left( L,\leq ,A,K,H\right) is an adjointness algebra. We call it \emph{Propositional Calculus for Adjointness Lattices}, abbreviated AdjLPCAdjLPC. Our axiom scheme for AdjLPCAdjLPC features four inference rules and thirteen axioms. We deduce enough theorems and inferences in AdjLPCAdjLPC to establish its completeness for ADJLADJL; by means of a quotient-algebra structure (a Lindenbaum type of algebra). We study two negation-like unary operations in an adjointness lattice, defined by means of 00 together with AA and HH. We end by developing complete syntax for all adjointness lattices whose implications are SS-type implications

    Cake Cutting Algorithms for Piecewise Constant and Piecewise Uniform Valuations

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    Cake cutting is one of the most fundamental settings in fair division and mechanism design without money. In this paper, we consider different levels of three fundamental goals in cake cutting: fairness, Pareto optimality, and strategyproofness. In particular, we present robust versions of envy-freeness and proportionality that are not only stronger than their standard counter-parts but also have less information requirements. We then focus on cake cutting with piecewise constant valuations and present three desirable algorithms: CCEA (Controlled Cake Eating Algorithm), MEA (Market Equilibrium Algorithm) and CSD (Constrained Serial Dictatorship). CCEA is polynomial-time, robust envy-free, and non-wasteful. It relies on parametric network flows and recent generalizations of the probabilistic serial algorithm. For the subdomain of piecewise uniform valuations, we show that it is also group-strategyproof. Then, we show that there exists an algorithm (MEA) that is polynomial-time, envy-free, proportional, and Pareto optimal. MEA is based on computing a market-based equilibrium via a convex program and relies on the results of Reijnierse and Potters [24] and Devanur et al. [15]. Moreover, we show that MEA and CCEA are equivalent to mechanism 1 of Chen et. al. [12] for piecewise uniform valuations. We then present an algorithm CSD and a way to implement it via randomization that satisfies strategyproofness in expectation, robust proportionality, and unanimity for piecewise constant valuations. For the case of two agents, it is robust envy-free, robust proportional, strategyproof, and polynomial-time. Many of our results extend to more general settings in cake cutting that allow for variable claims and initial endowments. We also show a few impossibility results to complement our algorithms.Comment: 39 page

    Permutation sampling in Path Integral Monte Carlo

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    A simple algorithm is described to sample permutations of identical particles in Path Integral Monte Carlo (PIMC) simulations of continuum many-body systems. The sampling strategy illustrated here is fairly general, and can be easily incorporated in any PIMC implementation based on the staging algorithm. Although it is similar in spirit to an existing prescription, it differs from it in some key aspects. It allows one to sample permutations efficiently, even if long paths (e.g., hundreds, or thousands of slices) are needed. We illustrate its effectiveness by presenting results of a PIMC calculation of thermodynamic properties of superfluid Helium-four, in which a very simple approximation for the high-temperature density matrix was utilized

    Ultra-low energy scattering of a He atom off a He dimer

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    We present a new, mathematically rigorous, method suitable for bound state and scattering processes calculations for various three atomic or molecular systems where the underlying forces are of a hard-core nature. We employed this method to calculate the binding energies and the ultra-low energy scattering phase shifts below as well as above the break-up threshold for the three He-atom system. The method is proved to be highly successful and suitable for solving the three-body bound state and scattering problem in configuration space and thus it paves the way to study various three-atomic systems, and to calculate important quantities such as the cross-sections, recombination rates etc.Comment: LaTeX, RevTeX and amssymb styles, 7 pages (25 Kb), 3 table
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