Soliton Models for the Nucleon and Predictions for the Nucleon Spin Structure

In these lectures the three flavor soliton approach for baryons is reviewed. Effects of flavor symmetry breaking in the baryon wave--functions on axial current matrix elements are discussed. A bosonized chiral quark model is considered to outline the computation of spin dependent nucleon structure functions in the soliton picture.Comment: 12 pages, Lectures presented at the Advanced Study Institute Symmetry and Spin, Prague, 2001, to appear in the proceedings. References correcte

Chiral Quark Model

In this talk I review studies of hadron properties in bosonized chiral quark models for the quark flavor dynamics. Mesons are constructed from Bethe--Salpeter equations and baryons emerge as chiral solitons. Such models require regularization and I show that the two--fold Pauli--Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions.Comment: Talk presented at the workshop QCD 2002, IIT Kanpur, Nov. 2002, 10 pages, proceedings style files include

Connected component identification and cluster update on GPU

Cluster identification tasks occur in a multitude of contexts in physics and engineering such as, for instance, cluster algorithms for simulating spin models, percolation simulations, segmentation problems in image processing, or network analysis. While it has been shown that graphics processing units (GPUs) can result in speedups of two to three orders of magnitude as compared to serial codes on CPUs for the case of local and thus naturally parallelized problems such as single-spin flip update simulations of spin models, the situation is considerably more complicated for the non-local problem of cluster or connected component identification. I discuss the suitability of different approaches of parallelization of cluster labeling and cluster update algorithms for calculations on GPU and compare to the performance of serial implementations.Comment: 15 pages, 14 figures, one table, submitted to PR

Substorm classification with the WINDMI model

International audienceThe results of a genetic algorithm optimization of the WINDMI model using the Blanchard-McPherron substorm data set is presented. A key result from the large-scale computations used to search for convergence in the predictions over the database is the finding that there are three distinct types of vx Bs -AL waveforms characterizing substorms. Type I and III substorms are given by the internally-triggered WINDMI model. The analysis reveals an additional type of event, called a type II substorm, that requires an external trigger as in the northward turning of the IMF model of Lyons (1995). We show that incorporating an external trigger, initiated by a fast northward turning of the IMF, into WINDMI, a low-dimensional model of substorms, yields improved predictions of substorm evolution in terms of the AL index. Intrinsic database uncertainties in the timing between the ground-based AL electrojet signal and the arrival time at the magnetopause of the IMF data measured by spacecraft in the solar wind prevent a sharp division between type I and II events. However, within these timing limitations we find that the fraction of events is roughly 40% type I, 40% type II, and 20% type III

Instability of the hedgehog shape for the octet baryon in the chiral quark soliton model

In this paper the stability of the hedgehog shape of the chiral soliton is studied for the octet baryon with the SU(3) chiral quark soliton model. The strangeness degrees of freedom are treated by a simplified bound-state approach, which omits the locality of the kaon wave function. The mean field approximation for the flavor rotation is applied to the model. The classical soliton changes shape according to the strangeness. The baryon appears as a rotational band of the combined system of the deformed soliton and the kaon.Comment: 24 pages, LaTeX, 8 eps file

Androgen receptor mutations in prostate cancer

We analyzed the frequency and relevance of mutations in the coding region of the androgen receptor (AR) in genomic DNA extracted from 137 specimens of prostate cancer. The specimens were obtained from the primary tumors of patients affected by stage B disease [15 nonmicrodissected (group 1A) and 84 microdissected (group 1B)] and from the metastatic deposits of individuals with stage D1 disease [8 nonmicrodissected (group 2A) and 30 microdissected (group 2B)] who had not undergone androgen ablation therapy. The study was conducted by PCR-single strand conformational polymorphism (SSCP) analysis of exons 2-8 in the four groups and direct sequence analysis of exon 1 in group 1B. As positive and negative controls, we used genomic DNA extracted from genital skin fibroblasts of patients affected by various forms of androgen resistance with known mutations in the AR. To control for genetic instability, PCR-SSCP analysis of exon 2 of the human progesterone receptor was carried out on each specimen. The overall number of mutations detected was 11 (8%). No mutations were detected in any of the 99 patients with stage B disease. Eleven mutations were detected in exons 2-8 in 8 of the 38 patients with stage D1 disease (all in group 2B). Simultaneous analysis of exon 2 of the progesterone receptor was carried out, and no SSCP changes were identified. These data suggest that AR mutations are rare and presumably do not play a role in the initial phase of prostatic carcinogenesis. The presence of a significant number of AR mutations in metastatic disease indicates that mutations of this molecule may play a role in the most advanced phases of the natural history of this disease, either by facilitating growth or acquisition of the metastatic phenotype

Outcomes of tuberculosis patients who start antiretroviral therapy under routine programme conditions in Malawi

SETTING: Public sector facilities in Malawi providing antiretroviral therapy (ART) to human immunodeficiency virus (HIV) positive patients, including those with tuberculosis (TB). OBJECTIVES: To compare 6-month and 12-month cohort treatment outcomes of HIV-positive TB patients and HIV-positive non-TB patients treated with ART. DESIGN: Retrospective data collection using ART patient master cards and ART patient registers. RESULTS: Between July and September 2005, 7905 patients started ART, 6967 with a non-TB diagnosis and 938 with a diagnosis of active TB. 6-month cohort outcomes of non-TB and TB patients censored on 31 March 2006 showed significantly more TB patients alive and on ART (77%) compared with non-TB patients (71%) (P < 0.001). Between January and March 2005, 4580 patients started ART, 4179 with a non-TB diagnosis and 401 with a diagnosis of active TB. 12-month cohort outcomes of non-TB and TB patients censored on 31 March 2006 showed significantly more TB patients alive and on ART (74%) compared with non-TB patients (66%) (P < 0.001). Other outcomes of default and transfer out were also significantly less frequent in TB compared with non-TB patients. CONCLUSION: HIV-positive TB patients on ART in Malawi have generally good treatment outcomes, and more patients need to access this HIV treatment

Parton distributions in the chiral quark model: a continuum computation

We compute the parton distributions for the chiral quark model. We present a new technique for performing such computations based on Green functions. This approach avoids a discretization of the spectrum. It therefore does not need any smoothing procedures. The results are similar to those of other groups, however the distributions peak at smaller $x$.Comment: 19 pages, 8 Figures, LaTeX, some typos corrected, some additional comments in the conclusion

Local positioning with sensor-enabled passive multistandard RFID transponders

RFID is used today in many fields of every day life like access control, anti-theft protection or logistics. Within this article a short overview of the basic RFID principles and the EPC protocol flow is given at first. Afterwards new design approaches for RFID systems within the scope of the research project RFID-S are presented