scholarly journals Computational Tools for Cohomology of Toric Varieties

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Ralph Blumenhagen ◽  
Benjamin Jurke ◽  
Thorsten Rahn

Novel nonstandard techniques for the computation of cohomology classes on toric varieties are summarized. After an introduction of the basic definitions and properties of toric geometry, we discuss a specific computational algorithm for the determination of the dimension of line-bundle-valued cohomology groups on toric varieties. Applications to the computation of chiral massless matter spectra in string compactifications are discussed, and using the software packagecohomCalg, its utility is highlighted on a new target space dual pair of(0,2)heterotic string models.

2016 ◽  
Vol 86 ◽  
pp. 02019 ◽  
Author(s):  
Anastasia Chulkova ◽  
Sergey Lukichev ◽  
Marina Romanovich

2015 ◽  
Vol 18 (1) ◽  
pp. 647-659 ◽  
Author(s):  
Jürgen Hausen ◽  
Simon Keicher

Mori dream spaces form a large example class of algebraic varieties, comprising the well-known toric varieties. We provide a first software package for the explicit treatment of Mori dream spaces and demonstrate its use by presenting basic sample computations. The software package is accompanied by a Cox ring database which delivers defining data for Cox rings and Mori dream spaces in a suitable format. As an application of the package, we determine the common Cox ring for the symplectic resolutions of a certain quotient singularity investigated by Bellamy–Schedler and Donten-Bury–Wiśniewski.


2018 ◽  
Author(s):  
Tejas R. Rao

We develop an efficient software package to test for the primality of p2^n+1, p prime and p>2^n. This aids in the determination of large, non-Sierpinski numbers p, for prime p, and in cryptography. It furthermore uniquely allows for the computation of the smallest n such that p2^n+1 is prime when p is large. We compute primes of this form for the first one million primes p and find four primes of the form above 1000 digits. The software may also be used to test whether p2^n+1 divides a generalized fermat number base 3.


2007 ◽  
Vol 22 (08n09) ◽  
pp. 1451-1588 ◽  
Author(s):  
MARY K. GAILLARD ◽  
BRENT D. NELSON

We review the theory and phenomenology of effective supergravity theories based on orbifold compactifications of the weakly-coupled heterotic string. In particular, we consider theories in which the four-dimensional theory displays target space modular invariance and where the dilatonic mode undergoes Kähler stabilization. A self-contained exposition of effective Lagrangian approaches to gaugino condensation and heterotic string theory is presented, leading to the development of the models of Binétruy, Gaillard and Wu. Various aspects of the phenomenology of this class of models are considered. These include issues of supersymmetry breaking and superpartner spectra, the role of anomalous U(1) factors, issues of flavor and R-parity conservation, collider signatures, axion physics, and early universe cosmology. For the vast majority of phenomenological considerations the theories reviewed here compare quite favorably to other string-derived models in the literature. Theoretical objections to the framework and directions for further research are identified and discussed.


Author(s):  
Victor N. Zvyagin ◽  
Elena E. Fomina ◽  
Olga I. Galitskaya ◽  
Nina V. Narina ◽  
Lyudmila L. Usacheva
Keyword(s):  

2019 ◽  
Vol 4 (11) ◽  
Author(s):  
Marilia Valli ◽  
Helena Mannochio Russo ◽  
Alan Cesar Pilon ◽  
Meri Emili Ferreira Pinto ◽  
Nathalia B. Dias ◽  
...  

Abstract Technological advances have contributed to the evolution of the natural product chemistry and drug discovery programs. Recently, computational methods for nuclear magnetic resonance (NMR) and mass spectrometry (MS) have speeded up and facilitated the process of structural elucidation even in high complex biological samples. In this chapter, the current computational tools related to NMR and MS databases and spectral similarity networks, as well as their applications on dereplication and determination of biological biomarkers, are addressed.


1995 ◽  
Vol 72 (11) ◽  
pp. 1405-1406 ◽  
Author(s):  
Michael J. Haas ◽  
Dominic Esposito ◽  
David J. Cichowicz

2020 ◽  
Vol 38 (4) ◽  
pp. 377-394
Author(s):  
Michael Spearpoint ◽  
Charlie Hopkin ◽  
Danny Hopkin

Kitchen hob fires present a potential threat to occupants escaping from dwellings and calculations may be needed to assess the hazard. Determination of the thermal heat flux from flames to a target can be achieved through the use of hand calculation methods or computational tools. This article compares point source, parallel plane and cylindrical view factor hand calculations and computational simulations using B-RISK and Fire Dynamics Simulator of thermal heat flux with kitchen hob fire experiments presented in the literature. Knowing the level of accuracy of each method provides useful information to designers. Although the point source model is influenced by whether the radial distance is measured perpendicular to the heat flux target or is offset relative to the centre of the flame, the article concludes that it provides an adequate approach for the calculation of thermal heat flux in the case of kitchen hob fires.


1997 ◽  
Vol 165 ◽  
pp. 347-350
Author(s):  
Andrzej Drożyner

AbstractIn the frame of European cooperation among some stations (Brussels, Praha, Cagliari, Torino, Penc, Borowiec, Teddington, Metsahovi, Besançon and San Fernando) the method of time comparisons by a TV link has been used for orbit determination of the Eutelsat-F2 satellite. Observational stations are equipped with commercial TV receivers and high stability time services. The technique of observations is based on the registration of arrival times of synchronous pulses broadcast by the satellite. For this type of observations a special orbital software package (TOP-COGEOS) has been developed, which allows the determination of the dynamical state of the satellite and some additional parameters connected to applied observational technique.


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