Are Time-Domain Self-Force Calculations Contaminated by Jost Solutions?

The calculation of the self force in the modeling of the gravitational-wave emission from extreme-mass-ratio binaries is a challenging task. Here we address the question of the possible emergence of a persistent spurious solution in time-domain schemes, referred to as a {\em Jost junk solution} in the literature, that may contaminate self force calculations. Previous studies suggested that Jost solutions are due to the use of zero initial data, which is inconsistent with the singular sources associated with the small object, described as a point mass. However, in this work we show that the specific origin is an inconsistency in the translation of the singular sources into jump conditions. More importantly, we identify the correct implementation of the sources at late times as the sufficient condition guaranteeing the absence of Jost junk solutions.Comment: RevTeX. 5 pages, 2 figures. Version updated to match the contents of the published articl

Creating a Vision for XYZ Research Corporation: A Case Study

A strategic analysis was developed for XYZ Research Corporation (the true company's name is disguised). The strategic analysis involved a series of visits to the company to conduct focus groups with its employees and management. Five focus groups were carried out at XYZ Research Corporation. This method proved to be effective and valuable when aiming to gather detailed information on the specifics of a firm's operation. Information and insights on the company and its business that would not become evident through any kind of meticulous financial or economic analysis of the company's and industry's numbers - which in fact were unavailable or scarce - was efficiently obtained by personal communication from the employees in the interviews. The focus group and interview method is recommended as a valid alternative to gathering detailed data and information when facing limited availability of reliable quantitative economic data on sales, size, and other information on the industry. The amount and quality of person-to-person information gathered in the interviews made the questionnaire a more powerful tool versus the alternative of simply mailing it. In the process of developing a strategic plan for XYZ, data and information used to write an undergraduate level teaching case study was gathered. The focus group method allowed for digging out intricate functional relationships within the company and between the company and the industry, which allowed for writing a more complete and educationally interesting case study.Focus Groups, Strategic Analysis, Food Safety, Outsourcing, Research Methods/ Statistical Methods, A22, C99, L21, M10,

Magnetism, structure, and charge correlation at a pressure-induced Mott-Hubbard insulator-metal transition

We use synchrotron x-ray diffraction and electrical transport under pressure to probe both the magnetism and the structure of single crystal NiS2 across its Mott-Hubbard transition. In the insulator, the low-temperature antiferromagnetic order results from superexchange among correlated electrons and couples to a (1/2, 1/2, 1/2) superlattice distortion. Applying pressure suppresses the insulating state, but enhances the magnetism as the superexchange increases with decreasing lattice constant. By comparing our results under pressure to previous studies of doped crystals we show that this dependence of the magnetism on the lattice constant is consistent for both band broadening and band filling. In the high pressure metallic phase the lattice symmetry is reduced from cubic to monoclinic, pointing to the primary influence of charge correlations at the transition. There exists a wide regime of phase separation that may be a general characteristic of correlated quantum matter.Comment: 5 pages, 3 figure

Shallot virus X: a hardly known pathogen of the genus Allium

Crops belonging to the genus Allium, family Amaryllidaceae, are economically important and are widely cultivated around the globe. Some of the most problematic diseases of these crops are caused by members of three virus genera, Potyvirus, Carlavirus and Allexivirus. Shallot virus X (ShVX) is an Allexivirus that was first discovered in Russia in the nineties and it has since been described worldwide. The virus, transmitted mechanically or by the dry bulb mite (Aceria tulipae), affects virtually all members of the genus Allium and it causes yield reductions on these crops. ShVX is a positive-sense single-stranded monopartite RNA virus that contains six open reading frames (ORFs). The virus is mainly detected by RT-PCR but there are other serological and molecular techniques available for diagnosis. There are no methods described for managing crops infected by ShVX in the field, but tissue culture of meristems can render virus-free plants. Research on the ShVX-Allium pathosystem is needed for a comprehensive understanding of the physiological and molecular mechanisms used by the virus to infect its hosts and for developing methods for the effective control of viral infections.Los cultivos del género Allium, familia Amaryllidaceae, son económicamente importantes y ampliamente sembrados alrededor del mundo. Algunas de las enfermedades más problemáticas de estos cultivos son ocasionadas por virus de tres géneros, Potyvirus, Carlavirus y Allexivirus. Shallot virus X (ShVX) es un Allexivirus que fue descrito por primera vez en Rusia en la década de los noventa y desde entonces se ha descrito su presencia a nivel mundial. El virus, transmitido mecánicamente o por el eriófido de los bulbos (Aceria tulipae), afecta prácticamente a todos los miembros del género Allium ocasionando la disminución en la producción de estos cultivos. ShVX tiene un genoma monopartito representado por una cadena simple de ARN de polaridad positiva con seis marcos abiertos de lectura (ORFs). El virus se detecta principalmente por RT-PCR, pero existen otros métodos serológicos y moleculares disponibles para su diagnóstico. No existen métodos descritos para el manejo de plantas infectadas con ShVX en el campo, sin embargo se ha determinado que el cultivo de tejidos meristemáticos puede producir plantas libres de virus. Es necesario desarrollar investigaciones en el patosistema ShVX-Allium para lograr un entendimiento general sobre los mecanismos fisiológicos y moleculares que utiliza el virus para infectar a su hospedero y para desarrollar métodos para el control efectivo de las infecciones virales.Gerencia de Comunicación e Imagen InstitucionalFil: Granda Jaramillo, Roberto. Universidad UTE. Facultad de Ciencias de la Ingeniería e Industrias; EcuadorFil: Flores, F. Universidad UTE. Facultad de Ciencias de la Ingeniería e Industrias. Centro de Investigación de Alimentos; Ecuador. Universidad de las Fuerzas Armadas. Departamento de Ciencias de la Vida y la Agricultura; Ecuado

Time-domain modelling of Extreme-Mass-Ratio Inspirals for the Laser Interferometer Space Antenna

When a stellar-mass compact object is captured by a supermassive black hole located in a galactic centre, the system losses energy and angular momentum by the emission of gravitational waves. Subsequently, the stellar compact object evolves inspiraling until plunging onto the massive black hole. These EMRI systems are expected to be one of the main sources of gravitational waves for the future space-based Laser Interferometer Space Antenna (LISA). However, the detection of EMRI signals will require of very accurate theoretical templates taking into account the gravitational self-force, which is the responsible of the stellar-compact object inspiral. Due to its potential applicability on EMRIs, the obtention of an efficient method to compute the scalar self-force acting on a point-like particle orbiting around a massive black hole is being object of increasing interest. We present here a review of our time-domain numerical technique to compute the self-force acting on a point-like particle and we show its suitability to deal with both circular and eccentric orbits.Comment: 4 pages, 2 figures, JPCS latex style. Submitted to JPCS (special issue for the proceedings of the Spanish Relativity Meeting (ERE2010)

Numerical implementation of isolated horizon boundary conditions

We study the numerical implementation of a set of boundary conditions derived from the isolated horizon formalism, and which characterize a black hole whose horizon is in quasiequilibrium. More precisely, we enforce these geometrical prescriptions as inner boundary conditions on an excised sphere, in the numerical resolution of the conformal thin sandwich equations. As main results, we first establish the consistency of including in the set of boundary conditions a constant surface gravity prescription, interpretable as a lapse boundary condition, and second we assess how the prescriptions presented recently by Dain et al. for guaranteeing the well-posedness of the conformal transverse traceless equations with quasiequilibrium horizon conditions extend to the conformal thin sandwich elliptic system. As a consequence of the latter analysis, we discuss the freedom of prescribing the expansion associated with the ingoing null normal at the horizon

Double layer charging driven carbon dioxide adsorption limits the rate of electrochemical carbon dioxide reduction on Gold.

Electrochemical CO[Formula: see text] reduction is a potential route to the sustainable production of valuable fuels and chemicals. Here, we perform CO[Formula: see text] reduction experiments on Gold at neutral to acidic pH values to elucidate the long-standing controversy surrounding the rate-limiting step. We find the CO production rate to be invariant with pH on a Standard Hydrogen Electrode scale and conclude that it is limited by the CO[Formula: see text] adsorption step. We present a new multi-scale modeling scheme that integrates ab initio reaction kinetics with mass transport simulations, explicitly considering the charged electric double layer. The model reproduces the experimental CO polarization curve and reveals the rate-limiting step to be *COOH to *CO at low overpotentials, CO[Formula: see text] adsorption at intermediate ones, and CO[Formula: see text] mass transport at high overpotentials. Finally, we show the Tafel slope to arise from the electrostatic interaction between the dipole of *CO[Formula: see text] and the interfacial field. This work highlights the importance of surface charging for electrochemical kinetics and mass transport