Drift Chamber Utilizing Microstrip Readout for Testing a New Micro TPC Concept

A drift chamber type radiation detector is being used to examine design criteria for a new type of detector called a micro Time Projection Chamber (micro TPC) which is being proposed for use in high energy nuclear physics experiments. The main advantage of the micro TPC detector is its very low radiation thickness compared to its silicon counterpart. The micro TPC is a charged-particle detector which willbe optimized for good two track resolution which is needed inahigh track density environment. Such performance requires low electron diffusion and high resolution readout. The diffusion willbe reduced bylimiting the drift distance to 15 cm and by using a low diffusion gas such as dimethyl ether. High resolution willbe obtained by using a new readout technology called microstrips. Microstrips are a recent development using photolithography techniques that allow the creation of anodes a few microns in width with submicron precision. The main purpose of this test chamber is to demonstrate the feasibility of a micro TPC design using a low diffusion gas and to insure the sufficient signal remains after electron attenuation. The driftchamber design and the proposed testingprocedures are described

Neutrons from multiplicity-selected Au-Au collisions at 150, 250, 400, and 650 AMeV

We measured neutron triple-differential cross sections from multiplicity-selected Au-Au collisions at 150, 250, 400, and 650 \AMeV. The reaction plane for each collision was estimated from the summed transverse velocity vector of the charged fragments emitted in the collision. We examined the azimuthal distribution of the triple-differential cross sections as a function of the polar angle and the neutron rapidity. We extracted the average in--plane transverse momentum $\langle P_x\rangle$ and the normalized observable $\langle P_x/P_\perp\rangle$, where $P_\perp$ is the neutron transverse momentum, as a function of the neutron center-of-mass rapidity, and we examined the dependence of these observables on beam energy. These collective flow observables for neutrons, which are consistent with those of protons plus bound nucleons from the Plastic Ball Group, agree with the Boltzmann--Uehling--Uhlenbeck (BUU) calculations with a momentum--dependent interaction. Also, we calculated the polar-angle-integrated maximum azimuthal anisotropy ratio R from the value of $\langle P_x/P_\perp\rangle$.Comment: 20 LaTeX pages. 11 figures to be faxed on request, send email to sender's addres

Role of macrophage sialoadhesin in host defense against the sialylated pathogen group B <em>Streptococcus</em>

ABSTRACT: Several bacterial pathogens decorate their surfaces with sialic acid (Sia) residues within cell wall components or capsular exopolysaccharides. Sialic acid expression can promote bacterial virulence by blocking complement activation or by engagement of inhibitory sialic acid-binding immunoglobulin-like lectins (Siglecs) on host leukocytes. Expressed at high levels on splenic and lymph node macrophages, sialoadhesin (Sn) is a unique Siglec with an elongated structure that lacks intracellular signaling motifs. Sialoadhesin allows macrophage to engage certain sialylated pathogens and stimulate inflammatory responses, but the in vivo significance of sialoadhesin in infection has not been shown. We demonstrate that macrophages phagocytose the sialylated pathogen group B Streptococcus (GBS) and increase bactericidal activity via sialoadhesin-sialic-acid-mediated recognition. Sialoadhesin expression on marginal zone metallophillic macrophages in the spleen trapped circulating GBS and restricted the spread of the GBS to distant organs, reducing mortality. Specific IgM antibody responses to GBS challenge were also impaired in sialoadhesin-deficient mice. Thus, sialoadhesin represents a key bridge to orchestrate innate and adaptive immune defenses against invasive sialylated bacterial pathogens. KEY MESSAGE: Sialoadhesin is critical for macrophages to phagocytose and clear GBS. Increased GBS organ dissemination in the sialoadhesin-deficient mice. Reduced anti-GBS IgM production in the sialoadhesin-deficient mice. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00109-014-1157-y) contains supplementary material, which is available to authorized users

Currency Unions

A currency union is when several independent sovereign nations share a common currency. This has been a recurring phenomenon in monetary history. In this article I study the theoretical foundations of such unions, and discuss some important currency unions in history, most notably the case of the US. Finally I contrast the design of the EMU with economic theories and historical experiences of currency unions

E-mail Prioritization through Social Network Analysis

Context. Trust and reliability are important issues in online communication. By rapid growth of online social networks (OSNs), online communication becomes richer by the integrating of social interaction into the communication model. However, E-mail communication systems concern about unsolicited messages. Objectives. In this thesis the aim is to investigate how to prioritize E-mails between recipients and senders by using information from OSNs. Methods. An algorithm is presented for computing trust by measuring users‟ interaction and similarity in online social networks and this trust is used by another algorithm for prioritizing the E-mail inbox. Results. An evaluation of the proposed method is performed via a case study and the prediction error of the method is compared with the prediction error of the random feedback. The error of the method is significantly lower than random feedback and is relatively low, given the small number of observations. Conclusions. This thesis contributes in its review and categorization of existing trust models. Furthermore, it provides an analysis on how to use social information for E-mail prioritization. Based on the analysis, a method is presented for improving the reliability of E-mail communication by extracting information from OSNs. The information is used for computing the trust score between two OSN friends. In this thesis, it is suggested that, inbox prioritization is achievable using the selected method.This thesis has addressed E-mail prioritization through social network by using social information. The task has been done by focusing on the interaction and similarity between friends in the OSN. A theoretical analysis has been performed in order to identify the characteristic of suitable trust model. An algorithm (Algorithm 1) has been suggested to estimate weights of different criteria of social information. In order to have the trust predictions based on the user‟s preferences, the algorithm adjusted the weights based on the user‟s feedback. In addition, another algorithm (Algorithm 2) has been proposed to compute trust scores and prioritize E-mails inbox. Finally, an algorithm (Algorithm 3) has been presented to evaluate the error of the computed (predicted) trust scores. In order to display the applicability of the method as well as to motivate the theoretical foundation, a case study was reported in which the proposed method was applied to Facebook. The analysis showed that the proposed method was feasible to be used, and it provided users a mean to prioritize E-mail inboxes based on the social information extracted from Facebook. The analysis indicated that least squares method was a suitable approach to estimate weights that were used in computing trust scores and thus prioritizing E-mails inbox

The surface-anchored NanA protein promotes pneumococcal brain endothelial cell invasion

In humans, Streptococcus pneumoniae (SPN) is the leading cause of bacterial meningitis, a disease with high attributable mortality and frequent permanent neurological sequelae. The molecular mechanisms underlying the central nervous system tropism of SPN are incompletely understood, but include a primary interaction of the pathogen with the blood-brain barrier (BBB) endothelium. All SPN strains possess a gene encoding the surface-anchored sialidase (neuraminidase) NanA, which cleaves sialic acid on host cells and proteins. Here, we use an isogenic SPN NanA-deficient mutant and heterologous expression of the protein to show that NanA is both necessary and sufficient to promote SPN adherence to and invasion of human brain microvascular endothelial cells (hBMECs). NanA-mediated hBMEC invasion depends only partially on sialidase activity, whereas the N-terminal lectinlike domain of the protein plays a critical role. NanA promotes SPN-BBB interaction in a murine infection model, identifying the protein as proximal mediator of CNS entry by the pathogen