Analogs of the double-Reissner-Nordstrom solution in magnetostatics and dilaton gravity: mathematical description and some physical properties

In this paper we consider a magnetic analog of the double-Reissner-Nordstrom solution and construct the corresponding magnetic potential A_\varphi in the explicit form. The behavior of the resulting solution under the Harrison transformation then naturally singles out the asymmetric black diholes - configurations composed of two non-extreme black holes possessing unequal masses, and charges equal in magnitude but opposite in sign - as its most general subclass for which equilibrium of the black-hole constituents can be achieved with the aid of the external magnetic (or electric) field. We also generalize the double-Reissner-Nordstrom solution to the dilaton gravity with arbitrary dilaton coupling, yielding as the result the 4-dimensional double-Gibbons-Maeda spacetime. The study of some physical properties of the solutions obtained leads, in particular, to very simple formulas for the areas of the horizons and surface gravities.Comment: 18 pages, 1 figure; title changed, typos corrected; a considerably extended version which includes the discussion of the magnetostatic case and the explicit formula for the magnetic potentia

Inside the Outbreak of the 2009 Influenza A (H1N1)v Virus in Mexico

Influenza viruses pose a threat to human health because of their potential to cause global disease. Between mid March and mid April a pandemic influenza A virus emerged in Mexico. This report details 202 cases of infection of humans with the 2009 influenza A virus (H1N1)v which occurred in Mexico City as well as the spread of the virus throughout the entire country.From May 1st to May 5th nasopharyngeal swabs, derived from 751 patients, were collected at 220 outpatient clinics and 28 hospitals distributed throughout Mexico City. Analysis of samples using real time RT-PCR revealed that 202 patients out of the 751 subjects (26.9%) were confirmed to be infected with the new virus. All confirmed cases of human infection with the strain influenza (H1N1)v suffered respiratory symptoms. The greatest number of confirmed cases during the outbreak of the 2009 influenza A (H1N1)v were seen in neighbourhoods on the northeast side of Mexico City including Iztapalapa, Gustavo A. Madero, Iztacalco, and Tlahuac which are the most populated areas in Mexico City. Using these data, together with data reported by the Mexican Secretariat of Health (MSH) to date, we plot the course of influenza (H1N1)v activity throughout Mexico.Our data, which is backed up by MSH data, show that the greatest numbers of the 2009 influenza A (H1N1) cases were seen in the most populated areas. We speculate on conditions in Mexico which may have sparked this flu pandemic, the first in 41 years. We accept the hypothesis that high population density and a mass gathering which took in Iztapalapa contributed to the rapid spread of the disease which developed in three peaks of activity throughout the Country

Fuzzy state feedback with double integrator and anti-windup for the Van de Vusse reaction

Chemical processes use to be non-minimum phase systems. Thereby, they are a challenge for control applications. In this paper, fuzzy state feedback is applied in the Van de Vusse reaction that has an inverse response. The control design has an integrator to enhance the control performance by eliminating the steady-state error when a step reference is applied. An anti-windup action is used to reduce the undershoot in the system response. In practice, it is not possible to have always access to all the state variables. Thus, a fuzzy state observer is implemented via LMIs. Frequently, the papers that show similar applications present some comments about disturbance rejection. To eliminate the steady-state error when a ramp reference is used, in this work, a second integrator is aggregated. Now, the anti-windup also reduces the overshoot generated due to the usage of two integrators in the final application

Functional and antibacterial characterization of electrospun nanofiber membranes made of chitosan and polyvinyl alcohol

The development of nanomaterials with improved functional characteristics is a priority because of their applicability in medicine. Therefore, in this study, chitosan nanofiber membranes were electrospun with polyvinyl alcohol supplemented with carboxymethyl cellulose and pectin. The membrane characterization included identifying the functional groups of each polymer, the surface appearance, and the absorption capacity of aqueous media, simulating the exudates of skin diseases. Membrane weight loss was close to 50 % during the first day, and they preserved their integrity throughout the study. The mechanical characteristics demonstrated that the membranes with adjuvants are flexible and tough. The rigidity of the membranes was between 10.49 MPa and 22.65 MPa, and this rigidity decreased with the addition of chitosan and pectin. With chitosan, the elongation at break (8.25 %) was higher but the elastic modulus (450.78 MPa) was lower than those recorded with the other polymers. The effect against Staphylococcus aureus occurs due to chitosan and only by contact. In particular, an inhibition zone increased with the addition of chitosan (178.21 mm2). However, carboxymethyl cellulose showed the least shrinkage (4.4 %). Therefore, it is possible to produce nanofibers to make chitosan and polyvinyl alcohol membranes with improved functional characteristics by the addition of adjuvant agents as an alternative to other skin healing materials