Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation

We discuss solutions of Vlasov-Einstein equation for collisionless dark matter particles in the context of a flat Friedmann universe. We show that, after decoupling from the primordial plasma, the dark matter phase-space density indicator Q remains constant during the expansion of the universe, prior to structure formation. This well known result is valid for non-relativistic particles and is not "observer dependent" as in solutions derived from the Vlasov-Poisson system. In the linear regime, the inclusion of velocity dispersion effects permits to define a physical Jeans length for collisionless matter as function of the primordial phase-space density indicator: \lambda_J = (5\pi/G)^(1/2)Q^(-1/3)\rho_dm^(-1/6). The comoving Jeans wavenumber at matter-radiation equality is smaller by a factor of 2-3 than the comoving wavenumber due to free-streaming, contributing to the cut-off of the density fluctuation power spectrum at the lowest scales. We discuss the physical differences between these two scales. For dark matter particles of mass equal to 200 GeV, the derived Jeans mass is 4.3 x 10^(-6) solar masses.Comment: 18 pages, 2 figures. Accepted for publication in JCA

A bending cell for small batches

This article presents the study that is done for the conception of an automated bending cell devoted to the processing of parts in small batches, gathering the real necessities of potential customers. Joining the maximum of possible information, on the present cells, is has been able to conceive an automated bending cell devoted to the bending of parts, with dif-ferent form, weight, thickness, etc., in small batches. To be able to reach the proposed objec-tives, the cell is equipped with auxiliary systems, such as ATC (Automatic Tool Change) allied to a tool warehouse, AGC (Automatic Gripper Change) with three different grippers, a repo-sition station, and a dedicated 7th axis in the press brake designed to dock a standard 6 axes robot, that provide to cell a sufficient grade of autonomy. Allied with the idea of creating a cell for small batches, is introduced the target of getting this cell at lower price as possible. Thus the cell acquires an extended application range very important for potential customers. To get real perception of the money saving when working with this automated bending cell comparisons between Man work times vs. machine work times in production of small batches have been made

Performance Investigations of IEEE 802.11 a54 Mbps WPA2 Laboratory Links

The increasing importance of wireless communications, involving electronic devices, has been widely recognized. Performance is a fundamental issue, resulting in more reliable and efficient communications. Security is also crucially important. Laboratory measurements are presented for several performance aspects of Wi-Fi IEEE 802.11a54 Mbps WPA2 point-to-point and four node point-to-multipoint links. Our study contributes to performance evaluation of this technology under WPA2 encryption, using available equipment (HP V-M200 access points and Linksys WPC600N adapters). New results are given from TCP and UDP experiments concerning TCP throughput versus TCP packet length, jitter and percentage datagram loss versus UDP datagram size. Comparisons are made to corresponding results for Open links. Conclusions are drawn about the comparative performance of the links. Keywords: Wi-Fi, WLAN, IEEE 802.11a, Wireless network laboratory performance, Multi-Node WPA2 link

Performance Evaluation of IEEE 802.11 ac WPA2 Laboratory Links

The increasing importance of wireless communications, involving electronic devices, has been widely recognized. Performance is a fundamental issue, resulting in more reliable and efficient communications. Security is also crucially important. Laboratory measurements are presented about several performance aspects of Wi-Fi IEEE 802.11ac WPA2 point-to-point links. Our study contributes to performance evaluation of this technology under WPA2 encryption, using available equipment (Cisco 2702i access points and TP-Link AC1900 USB 3.0 adapters). New results are given from TCP and UDP experiments concerning TCP throughput versus TCP packet length, jitter and percentage datagram loss versus UDP datagram size. Comparisons are made to corresponding results for WPA2 802.11n. Conclusions are drawn about the comparative performance of the links. Keywords: Wi-Fi, WLAN, IEEE 802.11ac, Wireless network laboratory performance, Point-to-Point WPA2 link

Trismus as the first manifestation of cholangiocarcinoma

The initial presentation of a cholangiocarcinoma (CC) as trismus due to metastasis to the parotid gland is extremely rare and no previous reports have been found in the literature. A 29-year-old woman presented trismus that initiated 2 months before admission, just after superior left third molar extraction. Physical examination revealed severe trismus and a mass in the parotid gland. Computed tomography (CT) showed a heterogeneous mass in the left parotid gland. The next day she presented jaundice, bilirubinuria, and fever, followed by massive bleeding, intravascular disseminated coagulation, and respiratory insufficiency. Two days later she died. At autopsy, the parotid tumor was identified as a metastasis from a CC of the extrabiliary tract. To our knowledge, this is the first reported case of a metastatic CC that initially presented as trismus due to a mass in the parotid gland. This case represents a rare but important diagnosis that otolaryngologists and oral surgeons should add to the catalog of uncommon causes of trismus

Cost efficiency and resistance to chemical attack of a fly ash geopolymeric mortar versus epoxy resin and acrylic paint coatings

This article presents results of an experimental investigation on the resistance to chemical attack (with sulphuric, hydrochloric and nitric acid) of several materials: OPC concrete, high-performance concrete, epoxy resin, acrylic painting and a fly ash-based geopolymeric mortar). Three types of acids with three high concentrations (10, 20 and 30%) were used to simulate long-term degradation. A cost analysis was also performed. The results show that the epoxy resin has the best resistance to chemical attack independently of the acid type and the acid concentration. However, the cost analysis shows that the epoxy resin-based solution is the least cost-efficient solution being 70% above the cost efficiency of the fly ash-based geopolymeric mortar

Produtos de hidratação em argamassas geopoliméricas à base de argila da Tunísia para reparação de estruturas de concreto

A reparação de estruturas degradadas de concreto representa uma oportunidade para a indústria da construção mas também um desafio para a comunidade científica. O desenvolvimento de novas argamassas de reparação constitui por isso uma importante área de investigação. Os geopolímeros são ligantes inovadores alternativos ao cimento Portland pelo que as argamassas à base destes materiais, geopolíméricas, apresentam algumas potencialidades no campo da reparação das estruturas de concreto. O presente artigo apresenta resultados de uma investigação sobre o desenvolvimento de argamassas geopoliméricas à base de uma argila da Tunísia sujeita a tratamento térmico. É incluída uma análise da argila e também dos produtos de hidratação da argamassa os quais apresentam fases geopoliméricas típicas

Caracterización de los niveles de contaminación auditiva en Bogotá: Estudio piloto

El objetivo de este trabajo fue caracterizar los niveles de contaminación auditiva en Bogotá.  Para esto, se seleccionaron ocho microambientes en cuatro zonas de la ciudad así como varios corredores viales, en donde se llevaron a cabo mediciones de presión sonora y filmaciones de las condiciones de tráfico de la vía adyacente.  Los niveles de ruido ambiental encontrados superaron en el 75 % de los casos los valores sugeridos por la norma nacional colombiana.  Éste fue el caso incluso para sectores tales como parques y hospitales.  Los resultados aquí reportados pueden ser utilizados para demostrar la importancia y complejidad del impacto que los vehículos tienen sobre los niveles de ruido en la ciudad

Leucemia mieloide aguda con diferenciación monocítica: reporte de un caso

We present a case of acute monocytic leukemia with monocytic differentiation in a 58-year-old male patient, who was admitted for emergency care at the Alberto Sabogal Sologuren National Hospital. The clinical and laboratory findings of the particular case are described, with emphasis on cytomorphology and immunophenotype. Likewise, a general presentation of the disease is made and, since it is a rare hematologic neoplasm, recommendations for its identification and reporting from the laboratory are proposed.Presentamos un caso de leucemia mieloide aguda con diferenciación monocítica en un paciente varón de 58 años, captado por atención de emergencia en el Hospital Nacional Alberto Sabogal Sologuren. Se describen los hallazgos clínicos y de laboratorio del caso particular, con énfasis en la citomorfología y el inmunofenotipo. Asimismo, se hace una exposición general de la enfermedad y por tratarse de una neoplasia hematológica poco frecuente, se proponen recomendaciones para su identificación y reporte desde el laboratorio

Leucemia mieloide aguda con diferenciación monocítica: reporte de un caso

Presentamos un caso de leucemia mieloide aguda con diferenciación monocítica en un paciente varón de 58 años, captado por atención de emergencia en el Hospital Nacional Alberto Sabogal Sologuren. Se describen los hallazgos clínicos y de laboratorio del caso particular, con énfasis en la citomorfología y el inmunofenotipo. Asimismo, se hace una exposición general de la enfermedad y por tratarse de una neoplasia hematológica poco frecuente, se proponen recomendaciones para su identificación y reporte desde el laboratorio