On a possible manifestation of f_1 trajectory in J/psi photoproduction

We analyze a possible manifestation of f_1-trajectory in elastic J/psi photoproduction at high energy and large momentum transfer. Inspite of the small contribution of f_1-trajectory in total cross sections, it becomes significant in various spin observables. In particular, we show that the crucial test for f_1-exchange can be made by measuring the single beam- and double parity- and beam-target asymmetries at large momentum transfers, where a strong deviation from the exchange of conventional Pomerons is expected. This effect is caused by the interference of natural (Pomeron) and unnatural (f_1) parity exchange parts of amplitude in the region where their contributions become comparable to each other and might be interesting to observe in forthcoming experiments, if feasible. .Comment: 8 pages, 10 figures. To be published in PL

A Comprehensive Approach to Structure Functions

We present a model based on a dipole picture with a hard and a soft pomeron in which large dipoles couple to the soft pomeron and small dipoles couple to the hard pomeron. The parameters in the model are fixed by proton-proton scattering and the proton structure function. The model is then applied successfully to the proton charm structure function, the proton longitudinal structure function, J/psi photoproduction, deep virtual Compton scattering, the real photon-proton total cross section, the real photon-photon cross section, and the photon structure function. Differences between our predictions and data on charm production in real photon-photon interactions and the virtual gamma-gamma cross section are discussed

Photodisintegration of the deuteron

The thesis is divided into three parts. In the first part, a general survey of the two-nucleon problem is given, with particular attention paid to those aspects which impinge directly on the photodisintegration of the deuteron. In the second part, we consider the conventional theory of deuteron photodisintegration, with the radiative interaction being taken as given on the basis of the gauge invariance of the non-relativistic Hamiltonian for the two-nucleon system. Differential cross-section and polarization formulae are presented, and a discussion given of previous calculations in this field. New calculations are carried out using the Gammel-Thaler type Y.L.A.M. phase parameters obtained in the analysis of Breit et al. Wherever possible, phenomenological wave-functions are used, and where this is not feasible, they are calculated from a suitable Gammel-Thaler potential. Differential cross-sections and polarizations are obtained for photon laboratory energies up to 130 MeV, the calculations being carried out both for a 4% and 6% deuteron D-state probability. Finally the results obtained are compared and contrasted with those of previous calculations, and both sets compared with experiments. In the third part of the thesis, the calculation of the matrix element for deuteron photodisintegration by dispersion relations is considered. There are twelve invariant amplitudes. The covariant form of the transition amplitude is related to the non-covariant (Pauli-matrix) form, which is further related to the individual multipole transition amplitudes. The Born terms of the covariant amplitudes are derived, and the dispersion relations written down in energy for a fixed difference in the photon-proton and photon-neutron momentum transfers. It is necessary to use this rather than a fixed momentum transfer, in order to exhibit explicitly all the poles in the dispersion relations. The dispersion relations contain integrals over both positive and negative energies, the latter arising from the crossed diagrams for which the imaginary part of the amplitude is related to processes such as the radiative absorption of an antie.nucleon by a deuteron, and to the structure of the deuteron through the anomalous singularities of the deamp vertex. These complications are ignored, and we retain only the pole terms and the integrals over positive energies. The relations are restricted to dipole and quadrupole transitions, and by considering the relations at two different "momentum transfers", equations are obtained explicitly for the individual electric dipole and magnetic dipole spin flip transition amplitudes. The equations are solved in a low energy approximation in which the final state nsp rescattering cut and single pion exchange cut only are considered, for the two cases of the Y.L.A.M. and Signell-Marshak phase-parameters. The results obtained are compared with those obtained in part two of the thesis

Vaccination frequency in people newly diagnosed with multiple sclerosis

Background: Infections are discussed as risk factor for multiple sclerosis (MS) development and relapses. This may lead to decreased vaccination frequency in newly diagnosed patients.Objective: The aim of this study was to evaluate the relation of MS diagnosis to subsequent vaccination frequency.Methods: Based on German ambulatory claims data from 2005 to 2019, regression models were used to assess the relation of MS diagnosis (n = 12,270) to vaccination. A cohort of patients with MS was compared to control cohorts with Crohn's disease, psoriasis, and without these autoimmune diseases (total n = 198,126) in the 5 years after and before diagnosis.Results: Patients with MS were less likely to be vaccinated compared to persons without the autoimmune diseases 5 years after diagnosis (odds ratio = 0.91, p < 0.001). Exceptions were vaccinations against influenza (1.29, p < 0.001) and pneumococci (1.41, p < 0.001). Differences were strong but less pronounced after than before diagnosis (p < 0.001). The likelihood of vaccination was also lower compared to patients with Crohn's disease or psoriasis.Conclusions: Patients with MS were not adequately vaccinated despite guideline recommendations. Increasing awareness about the importance of vaccination is warranted to reduce the risk of infection, in particular, in patients with MS receiving immunotherapies

Association of pregnancies with risk of multiple sclerosis

Background: Pregnancies have an impact on the disease course of multiple sclerosis (MS), but their relationship with MS risk is yet unclear. Objective: To determine the relationships of pregnancies and gynecological diagnoses with MS risk. Methods: In this retrospective case-control study, we assessed differences in gynecological International Classification of Diseases, 10th Revision (ICD-10) code recording rates between women with MS (n = 5720), Crohn's disease (n = 6280), or psoriasis (n = 40,555) and women without these autoimmune diseases (n = 26,729) in the 5 years before diagnosis. Results: Twenty-eight ICD-10 codes were recorded less frequently for women with MS as compared to women without autoimmune disease, 18 of which are pregnancy-related. After adjustment for pregnancies, all codes unrelated to pregnancies were still negatively associated with MS. In a sensitivity analysis excluding women with evidence for possible demyelinating events before diagnosis, all associations were more pronounced. In comparison to women with psoriasis, most associations could be confirmed;that was not true in comparison to women with Crohn's disease. Conclusion: Our findings provide evidence for a possible protective effect of pregnancies on MS risk likely independent of or in addition to a previously suggested reversed causality. The negative associations of gynecological disorders with disease risk need further investigation. The associations might be shared by different autoimmune diseases

Probing nucleon strangeness structure with phi electroproduction

We study the possibility to constrain the hidden strangeness content of the nucleon by means of the polarization observables in phi meson electroproduction. We consider the OZI evading direct knockout mechanism that arises from the non-vanishing s\bar{s} sea quark admixture of the nucleon as well as the background of the dominant diffractive and the one-boson-exchange processes. Large sensitivity on the nucleon strangeness are found in several beam-target and beam-recoil double polarization observables. The small \sqrt{s} and W region, which is accesible at some of the current high-energy electron facilities, is found to be the optimal energy region for extracting out the OZI evasion process.Comment: 8 pages, LaTeX2e, elsart.cls, 3 figures (4 eps files

A Systematic Assessment of Prevalence, Incidence and Regional Distribution of Multiple Sclerosis in Bavaria From 2006 to 2015

Introduction: Worldwide, incidence and prevalence of multiple sclerosis (MS) have increased over the last decades. We present a systematic epidemiological study with recent prevalence and incidence rates of MS in Bavaria. Methods: Incidence and prevalence of MS stratified by gender, age groups and region were analyzed by data records from 2006 to 2015 of more than 10 million people insured by the Bavarian Association of Statutory Health Insurance Physicians. Official statistics of the German Federal Ministry of Health provided the size of the general population. Future prevalence was estimated with a predictive model. Results: From 2006 to 2015 prevalence of MS in Bavaria increased from 171 per 100,000 to 277 per 100,000, while incidence rates remained relatively stable (range 16-18 per 100,000 inhabitants with a female to male ratio between 2.4:1 and 2:1). Incidence and prevalence were higher in urban than urbanized and rural areas. The prevalence is expected to increase to 374 per 100,000 in 2040 with the highest prevalence rates between 50 and 65 years. Conclusion: The prevalence of MS in Bavaria is among the highest worldwide and will further rise over the next two decades. This demonstrates a need to strengthen healthcare provision systems due to the increasing numbers of particularly older patients with MS in the future