Reentry vehicles: evaluation of plasma effects on RF propagation

In the frame of communication technology relevant to the re-entry vehicles, the communication black-out occurring in the presence of plasma is one of the main challenging issues. The re-entry plasma is a complex physical system, where the ionization derives from a shock-wave and non-equilibrium phenomena. As discussed elsewhere, the time scales of plasma dynamics (including its evolution along mission trajectory) and radio wave propagation are well separated so that radio wave propagation is solved at an appropriate number of time "snapshots" in which plasma dynamics is held unchanged and considered as known. In this activity, a consistent effort has been devoted to model the electromagnetic problem. For the involved range of oprative frequencies and expected densities, the plasma can be considered as an inhomogeneous dielectric. The associated electromagnetic problem is solved in two steps, via use of the field equivalence principle. The vehicle-plasma system is substituted by equivalent (Love's) currents on its boundary, radiating in free space; the fields at the boundary are obtained by solving the propagation problem from the antenna, installed on the spacecraft, up to the plasma boundary, through the Eikonal approximation. Radiation is then obtained without further approximations. Unlike other well-known numerical methods (e.g. FEM), this technique is not intrinsecally limited by the electrical dimension of the vehicle-plasma system. This enables to analyze high frequency problems. Since the formation of the re-entry plasma critically depends on the re-entry vehicle shape and kinematics, the related model has been directly derived from the output data of the Computational Fluid Dynamics simulations. All the results of the above mentioned activities have been collected in a new software, the AIPT (Antenna In Plasma Tool, integrated into ADF-EMS Antenna Design Framework Electromagnetic Satellite) able to predict the electromagnetic propagation in the presence of plasm

Estudo comparativo entre as microscopias de contraste de fase e contraste de interferência diferencial para análise de sêmen congelado de bovinos

Two hundred ampules of frozen bull semen were evaluated for per cent acrosomal pathology and major and minor defects of spermatozoa. The ampules referred to 4 groups of 50 each, corresponding to semen frozen in 1975, 1976, 1977 and 1978. Semen examinations were made after thawing and after being placed in a 38°C water bath for 5 hours (Slow Thermo resistance Test) or in a 45°C water bath for 1 hour (Quick Thermo resistance Test). Analysis of variance showed highly significant differences (P<.01)between phase-contrast and differential interference contrast microscopies for evaluation of acrosomal pathology and major defects of spermatozoa. For minor defects analysis of variance did not show statistical differences between the two technics employed.Duzentas ampolas de sêmen de bovinos, constituindo 4 grupos de 50, correspondentes a congelamentos efetuados, respectivamente, nos anos de 1975, 1976, 1977 e 1978, foram estudadas para avaliação da porcentagem de patologia do acrossomo e de defeitos maiores e menores. Os exames foram realizados após o descongelamento e após submissão às provas rápida (1 hora a 45°C) e lenta (5 horas a 38°C) de termo resistência, em microscopia de contraste de fase e em microscopia de contraste de interferência diferencial. Os resultados das análises de variância mostraram haver diferença estatística, altamente significante (P<0,01), a favor da microscopia de contraste de interferência diferencial para patologia do acrossomo e defeitos maiores, o mesmo não ocorrendo em relação aos defeitos menores

LPS-TLR4 Signaling to IRF-3/7 and NF-κB Involves the Toll Adapters TRAM and TRIF

Toll–IL-1–resistance (TIR) domain–containing adaptor-inducing IFN-β (TRIF)–related adaptor molecule (TRAM) is the fourth TIR domain–containing adaptor protein to be described that participates in Toll receptor signaling. Like TRIF, TRAM activates interferon regulatory factor (IRF)-3, IRF-7, and NF-κB-dependent signaling pathways. Toll-like receptor (TLR)3 and 4 activate these pathways to induce IFN-α/β, regulated on activation, normal T cell expressed and secreted (RANTES), and γ interferon–inducible protein 10 (IP-10) expression independently of the adaptor protein myeloid differentiation factor 88 (MyD88). Dominant negative and siRNA studies performed here demonstrate that TRIF functions downstream of both the TLR3 (dsRNA) and TLR4 (LPS) signaling pathways, whereas the function of TRAM is restricted to the TLR4 pathway. TRAM interacts with TRIF, MyD88 adaptor–like protein (Mal)/TIRAP, and TLR4 but not with TLR3. These studies suggest that TRIF and TRAM both function in LPS-TLR4 signaling to regulate the MyD88-independent pathway during the innate immune response to LPS

Avaliação do sêmen de reprodutores zebuínos visando a sua utilização em inseminação artificial

The semen picture of 13 zebu bulls, used as donors in an Artificial Insemination Center, was studied weekly during nine weeks. Average seminal characteristics were as follows: volume ranged from 7.89 to 13.44 ml progressive motility from 48 .6 3 to 73.89%, spermatic concentration from 712.000 to 1.774.000 spermatozoa / mm3. Spermatic pathology percentage observed with DIC and phase contrast microscopy, varied, respectively to total, major and minor defects, from 11.83 to 45.87%; from 3.50 to 35.50% and from 1.72 to 14.90% and from 7.56 to 42.3 4% from 2.83 to 31.02% and from 1.72 to 11.32%. Results based on a single examination of semen did not offer sufficient information because many samples with a high percentage of abnormal spermatozoa exhibited normal motility. The DIC microscopy was appreciably superior that of phase contrast for observation of spermatic defects.O quadro espermático de 13 touros Zebus, doadores em Central de Inseminação Artificial, foi estuda do em colheitas semanais obtidas por meio de eletroejaculação, durante 3 semanas. As características seminais foram, em média, volume de 7,89 a 13,44 ml. motilidade progressiva retilínea de 48, 83 a 73,831, concentração de 712.000 a 1.774.000 espermatozoides por mm3. A taxa de patologia espermática, através das microscopias de contraste de interferência diferencial e de contraste de fase juntamente com a coloração Williams, variou respectivamente, para defeitos totais, maiores e menores, de 11,83 a 45,871; 3,50 a 35,50% e 1,72 a 14,90% e 7, 55 a 42,34%; 2,83 a 31,02% e 1,72 a 11,32%. Constatou-se, ainda, que uma única prova não constitui elemento suficiente para a avaliação do sêmen, pois muitas amostras que apresentaram motilidade possuem altas porcentagens de espermatozoides anormais e que a microscopia de contraste de interferência diferencial mostrou-se sensivelmente superior ao contraste de fase para a observação de defeitos espermáticos

Direct, extended, and mass-mediated contact with immigrants in Italy: Their associations with emotions, prejudice, and humanity perceptions

Two correlational studies investigated the associations between different forms of intergroup contact, on the one hand, and Italians' prejudice and humanity attributions toward immigrants in Italy, on the other. Study 1 examined the effects of direct contact, extended contact, and parasocial contact through mass-media, assessing separately contact through TV news and newspapers and contact through entertainment programs. Study 2 analyzed the distinct effects of positive and negative episodes of the contact forms considered in Study 1. Across the studies, we tested the mediational role of intergroup anxiety, empathy, and trust. Overall, results showed the importance of taking into account different forms of contact and considering the emotional processes during contact experiences to understand intergroup attitudes

Direct, extended, and mass-mediated contact with immigrants in Italy: their associations with emotions, prejudice, and humanity perceptions

Two correlational studies investigated the associations between different forms of intergroup contact, on the one hand, and Italians' prejudice and humanity attributions toward immigrants in Italy, on the other. Study 1 examined the effects of direct contact, extended contact, and parasocial contact through mass-media, assessing separately contact through TV news and newspapers and contact through entertainment programs. Study 2 analyzed the distinct effects of positive and negative episodes of the contact forms considered in Study 1. Across the studies, we tested the mediational role of intergroup anxiety, empathy, and trust. Overall, results showed the importance of taking into account different forms of contact and considering the emotional processes during contact experiences to understand intergroup attitudes

Imagined intergroup contact promotes cooperation through outgroup trust

The present research aims to investigate whether salience of memberships during imagined contact is necessary for producing generalized positive attitudes toward the outgroup and promoting intergroup cooperation. After a warm-up task that involved reciprocal self-disclosure during the imagined interaction with an outgroup member, we manipulated interpersonal versus intergroup features of imagined contact. Results indicated that participants who imagined a conversation with a Muslim focusing on intergroup differences subsequently reported more positive attitudes and cooperative intentions toward Muslim immigrants compared to either participants who imagined the interaction at the interpersonal level or participants in a control condition. Moreover, these effects were found to be mediated by outgroup trust. These findings attest to the strength of interventions based on imagined intergroup contact and suggest a possible implementation of the technique

Imagined intergroup contact promotes cooperation through outgroup trust

The present research aims to investigate whether salience of memberships during imagined contact is necessary for producing generalized positive attitudes toward the outgroup and promoting intergroup cooperation. After a warm-up task that involved reciprocal self-disclosure during the imagined interaction with an outgroup member, we manipulated interpersonal versus intergroup features of imagined contact. Results indicated that participants who imagined a conversation with a Muslim focusing on intergroup differences subsequently reported more positive attitudes and cooperative intentions toward Muslim immigrants compared to either participants who imagined the interaction at the interpersonal level or participants in a control condition. Moreover, these effects were found to be mediated by outgroup trust. These findings attest to the strength of interventions based on imagined intergroup contact and suggest a possible implementation of the technique

Lysines 128 and 132 enable lipopolysaccharide binding to MD-2, leading to Toll-like receptor-4 aggregation and signal transduction

Three cell-surface proteins have been recognized as components of the mammalian signaling receptor for bacterial lipopolysaccharide (LPS): CD14, Toll-like receptor-4 (TLR4), and MD-2. Biochemical and visual studies shown here demonstrate that the role of CD14 in signal transduction is to enhance LPS binding to MD-2, although its expression is not essential for cellular activation. These studies clarify how MD-2 functions: we found that MD-2 enables TLR4 binding to LPS and allows the formation of stable receptor complexes. MD-2 must be bound to TLR4 on the cell surface before binding can occur. Consequently, TLR4 clusters into receptosomes (many of which are massive) that recruit intracellular toll/IL-1/resistance domain-containing adapter proteins within minutes, thus initiating signal transduction. TLR4 activation correlates with the ability of MD-2 to bind LPS, as MD-2 mutants that still bind TLR4, but are impaired in the ability to bind LPS, conferred a greatly blunted LPS response. These findings help clarify the earliest events of TLR4 triggering by LPS and identify MD-2 as an attractive target for pharmacological intervention in endotoxin-mediated diseases