Some Problems on the Classical N-Body Problem

Our idea is to imitate Smale's list of problems, in a restricted domain of mathematical aspects of Celestial Mechanics. All the problems are on the n-body problem, some with different homogeneity of the potential, addressing many aspects such as central configurations, stability of relative equilibrium, singularities, integral manifolds, etc. Following Steve Smale in his list, the criteria for our selection are: (1) Simple statement. Also preferably mathematically precise, and best even with a yes or no answer. (2) Personal acquaintance with the problem, having found it not easy. (3) A belief that the question, its solution, partial results or even attempts at its solution are likely to have great importance for the development of the mathematical aspects of Celestial Mechanics.Comment: 10 pages, list of mathematical problem

Aegithus clavicornis (Linnaeus) (Coleoptera: Erotylidae) in the Dominican Republic

Establishment of fungus beetles (Coleoptera: Erotylidae) in new isolated countries is rare. We report Aegithus clavicornis (Linnaeus) for the first time from the Dominican Republic, representing the first true record for this genus from the Greater Antilles

Incentives for Cost Reduction under Export Restraints. Incitations à l'innovation afin de réduire les coûts de production sous des restrictions quantitatives à l'importation..

The effect of trade quotas on firms’ incentive to invest in cost-reducing R&D is studied in a two-stage price-setting duopoly game. A domestic and a foreign firm first choose R&D levels and then set the prices of their differentiated products in the domestic market. With a quota imposed at, or close to, the free-trade level of imports, the domestic firm faces less competition than under free-trade and invests less in R&D. Contrarily, the constrained foreign firm invests more in R&D as the negative strategic effect of a reduction in its cost is now absent. These results differ partially from the Cournot duopoly case in which R&D expenditures are lower for both the firms. As the quota becomes more restrictive, the domestic firm increases and the foreign firm decreases its expenditures on R&D. Domestic welfare is always higher under free-trade than under any quota regardless of the degree of product substitutability.---------------------------------------------------------------------------Dans cet article, une firme nationale et une firme étrangère choisissent leurs niveaux de R&D dans un premier temps, puis fixent les prix de leurs produits différenciés sur le marché national. Si le quota imposé est égal ou est suffisamment proche du niveau des importations sous libre échange, la firme nationale investit moins en R&D. La firme étrangère contrainte investit plus, vu que l'effet stratégique négatif de la réduction des coûts par la R&D disparàît. On montre aussi que le niveau de bien-être national est toujours plus élevé sous libre échange indépendamment du degré de substituabilité des produits.

From vortex molecules to the Abrikosov lattice in thin mesoscopic superconducting disks

Stable vortex states are studied in large superconducting thin disks (for numerical purposes we considered with radius R = 50 \xi). Configurations containing more than 700 vortices were obtained using two different approaches: the nonlinear Ginzburg-Landau (GL) theory and the London approximation. To obtain better agreement with results from the GL theory we generalized the London theory by including the spatial variation of the order parameter following Clem's ansatz. We find that configurations calculated in the London limit are also stable within the Ginzburg-Landau theory for up to ~ 230 vortices. For large values of the vorticity (typically, L > 100), the vortices are arranged in an Abrikosov lattice in the center of the disk, which is surrounded by at least two circular shells of vortices. A Voronoi construction is used to identify the defects present in the ground state vortex configurations. Such defects cluster near the edge of the disk, but for large L also grain boundaries are found which extend up to the center of the disk.Comment: 15 pages, 10 figures, RevTex4, submitted to Phys. Rev.

Vacuum Polarization by a Magnetic Flux Tube at Finite Temperature in the Cosmic String Spacetime

In this paper we analyse the effect produced by the temperature in the vacuum polarization associated with charged massless scalar field in the presence of magnetic flux tube in the cosmic string spacetime. Three different configurations of magnetic fields are taken into account: $(i)$ a homogeneous field inside the tube, $(ii)$ a field proportional to $1/r$ and $(iii)$ a cylindrical shell with $\delta$-function. In these three cases, the axis of the infinitely long tube of radius $R$ coincides with the cosmic string. Because the complexity of this analysis in the region inside the tube, we consider the thermal effect in the region outside. In order to develop this analysis, we construct the thermal Green function associated with this system for the three above mentioned situations considering points in the region outside the tube. We explicitly calculate in the high-temperature limit, the thermal average of the field square and the energy-momentum tensor.Comment: 16 pages, 1 figur

Estimating plasma volume in neonatal Holstein calves fed one or two feedings of a lacteal-based colostrum replacer using Evans blue dye and hematocrit values at various time points.

Twenty-eight Holstein calves were blocked by birth date and randomly assigned to one of two treatments to investigate the effect of colostrum replacer (CR) feeding regimen on plasma volume (PV). Treatments were: 1) one feeding of CR (C1; 3L of reconstituted CR 675 g of powder providing 184.5 g of IgG at birth) or 2) two feedings of CR (C2; 2L of reconstituted CR at birth and 1 L of reconstituted CR at six h). By 6 h of age, all calves had received 3L of CR providing 184.5 g of IgG. Plasma volume was estimated at six, 12, 18, and 24 h after birth using Evans blue dye (EBD). No treatment effects were noted at any time points (P \u3e 0.05). Mean PV for all calves regardless of treatment at six, 12, 18, and 24 h were 78.6, 89.2, 83.9, and 90.7 mL kg-1 of BW, respectively. Plasma volume was correlated with hematocrit (HCT), initial HCT, and treatment. Hematocrit was correlated with PV, initial HCT, and body weight. Hematocrit for six, 12, 18 and 24 h after birth can be predicted with an initial precolostral HCT determination

Modeling the Obscuring Features in Active Galactic Nuclei: an X-Ray Analysis of NGC 1052

We present a multi-epoch analysis of the X-ray spectrum of NGC 1052, a nearby galaxy notorious for its well-studied spectral variability. We utilize observations from NuSTAR, XMM-Newton, Chandra, Swift, Suzaku, BeppoSAX, and ASCA to create a comprehensive set of data that spans roughly 20 years. Organizing our data by observation date and grouping into specific epochs allows us to explore a model allowed to flex and accommodate any spectral changes that occur over time in the X-ray spectrum of NGC 1052. We find that the spectrum takes on a relatively flat nature and is best modeled with two neutral absorption components in addition to a component representing torus reprocessing. We are able to successfully constrain properties of the dense obscuring torus, reporting a high covering factor of ∼ 80%

MANNA FROM HEAVEN: THE EXUBERANCE OF FOOD AS A TOPIC FOR RESEARCH IN MANAGEMENT AND ORGANIZATION

Organizations have, in the past, often been discussed as if they were Cartesian mentalities, planning agendas, learning from doing, processing information, reducing equivocality, mimicking and copying, floating disembodiedly apart from the actors who work in these organizations. We are offered representations of organizations as organically grounded metaphors that minimize the biological facticity of employees: namely, their need for food. While the inputs to organizations conceived as if they were quasi-systems are well explored, and the emotional and ‘irrational’ side of organizations is increasingly explored, the necessity of inputs to the biological systems that staff them is not. Nonetheless, despite the lack of explicit scholarly attention to food at work, its importance guarantees its hidden presence in the organizational literature, often in the context of more “serious” themes. We identify four approaches to the relationship between food, work and organization. For dessert, we propose a research menu that aims to uncover several possibilities for making the role of food in organizational life more explicit.

A semiquantitative approach to the impurity-band-related transport properties of GaMnAs nanolayers

We investigate the spin-polarized transport of GaMnAs nanolayers in which a ferromagnetic order exists below a certain transition temperature. Our calculation for the self-averaged resistivity takes into account the existence of an impurity band determining the extended ("metallic" transport) or localized (hopping by thermal excitation) nature of the states at and near the Fermi level. Magnetic order and resistivity are inter-related due to the influence of the spin polarization of the impurity band and the effect of the Zeeman splitting on the mobility edge. We obtain, for a given range of Mn concentration and carrier density, a "metallic" behavior in which the transport by extended carriers dominates at low temperature, and is dominated by the thermally excited localized carriers near and above the transition temperature. This gives rise to a conspicuous hump of the resistivity which has been experimentally observed and brings light onto the relationship between transport and magnetic properties of this material

Narrative Health Communication and Behavior Change: The Influence of Exemplars in the News on Intention to Quit Smoking.

This study investigated psychological mechanisms underlying the effect of narrative health communication on behavioral intention. Specifically, the study examined how exemplification in news about successful smoking cessation affects recipients\u27 narrative engagement, thereby changing their intention to quit smoking. Nationally representative samples of U.S. adult smokers participated in 2 experiments. The results from the 2 experiments consistently showed that smokers reading a news article with an exemplar experienced greater narrative engagement compared to those reading an article without an exemplar. Those who reported more engagement were in turn more likely to report greater smoking cessation intentions