On gg-natural conformal vector fields on unit tangent bundles

summary:We study conformal and Killing vector fields on the unit tangent bundle, over a Riemannian manifold, equipped with an arbitrary pseudo-Riemannian $g$-natural metric. We characterize the conformal and Killing conditions for classical lifts of vector fields and we give a full classification of conformal fiber-preserving vector fields on the unit tangent bundle endowed with an arbitrary pseudo-Riemannian Kaluza-Klein type metric

g ‐natural symmetries on tangent bundles

The study of symmetries is a well known research topic in differential geometry with relevant physical interpretations. Given a Riemannian manifold $(, )$, we consider pseudo-Riemannian $$-natural metrics$$ on its tangent bundle and characterize conformal, homothetic and Killing vector fields of $(,)$ obtained from natural lifts of vector fields of

Report of the Tunisian Registry of Primary Immunodeficiencies: 25-Years of Experience (1988-2012)

International audiencePrimary immunodeficiencies (PIDs) are a large group of diseases characterized by susceptibility to not only recurrent infections but also autoimmune diseases and malignancies. The aim of this study was to describe and analyze the distribution, clinical features and eventual outcome of PID among Tunisian patients. We reviewed the record of 710 patients diagnosed with Primary Immunodeficiency Diseases (PIDs) from the registry of the Tunisian Referral Centre for PIDs over a 25-year period. The male-to-female ratio was 1.4. The median age at the onset of symptoms was 6 months and at the time of diagnosis 2 years. The estimated prevalence was 4.3 per 100,000 populations. The consanguinity rate was found in 58.2 % of families. According to the International Union of Immunological Societies classification, spectrums of PIDs were as follows: combined T-cell and B-cell immunodeficiency disorders account for the most common category (28.6 %), followed by congenital defects of phagocyte (25.4 %), other well-defined immunodeficiency syndromes (22.7 %), predominant antibody deficiency diseases (17.7 %), diseases of immune dysregulation (4.8 %), defect of innate immunity (0.4 %) and complement deficiencies (0.4 %). Recurrent infections, particularly lower airway infections (62.3 %), presented the most common manifestation of PID patients. The overall mortality rate was 34.5 %, mainly observed with combined immunodeficiencies. The distribution of PIDs was different from that reported in Western countries, with a particularly high proportion of Combined Immunodeficiencies and phagocyte defects in number and/or function. More is needed to improve PID diagnosis and treatment in our country