Humboldt University of Berlin

About: Humboldt University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Transplantation. The organization has 33671 authors who have published 61781 publications receiving 1908102 citations. The organization is also known as: Humboldt-Universität zu Berlin & Universitas Humboldtiana Berolinensis.

Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma Rays around Periastron with H.E.S.S

Abstract: We report the discovery of very-high-energy (VHE) γ-ray emission of the binary system PSR B1259−63/SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron passage of the pulsar were performed with the four 13 m Cherenkov telescopes of the HESS experiment, recently installed in Namibia and in full operation since December 2003. Between February and June 2004, a γ-ray signal from the binary system was detected with a total significance above 13σ. The flux was found to vary significantly on timescales of days which makes PSR B1259−63 the first variable galactic source of VHE γ-rays observed so far. Strong emission signals were observed in pre- and post-periastron phases with a flux minimum around periastron, followed by a gradual flux decrease in the months after. The measured time-averaged energy spectrum above a mean threshold energy of 380 GeV can be fitted by a simple power law F0(E/ 1T eV) −Γ with a photon index Γ= 2.7 ± 0.2stat ± 0.2sys and flux normalisation F0 = (1.3 ± 0.1stat ± 0.3sys) × 10 −12 TeV −1 cm −2 s −1 .T his detection of VHE γ-rays provides unambiguous evidence for particle acceleration to multi-TeV energies in the binary system. In combination with coeval observations of the X-ray synchrotron emission by the RXTE and INTEGRAL instruments, and assuming the VHE γ-ray emission to be produced by the inverse Compton mechanism, the magnetic field strength can be directly estimated to be of the order of 1 G.

Long-term outcome in patients with juvenile idiopathic arthritis.

Abstract: Objective To describe the long-term outcome of juvenile idiopathic arthritis (JIA). Methods All patients with JIA referred to a pediatric rheumatology center between 1978 and 1988 were identified and invited to undergo an assessment. Patients with JIA from a population-based cohort from East Berlin were included. The outcome assessment considered changes in body function and structure (e.g., mortality, joint abnormalities, disease activity), activities at the individual level (Health Assessment Questionnaire), and participation in society (e.g., mobility, educational and vocational background). Results Of 260 eligible patients, 215 (83%) were evaluated. Subtypes of JIA at disease onset included oligoarthritis (40%), polyarthritis (14%), systemic arthritis (14%), psoriatic arthritis (1%), enthesitis-related arthritis (15%), and other arthritis (16%). Followup was conducted after a median of 16.5 years. No deaths occurred in this cohort. At followup, approximately half of the patients had active disease and/or changes in body structures to a variable extent. Approximately one-third of patients rated themselves as being functionally limited. Patients demonstrated good social integration: few mobility problems were reported, and the educational achievements of patients were higher and their rate of unemployment was lower compared with the age-matched population. No significant differences in outcome were found between the population-based and the referral-based cohorts. Conclusion Even though approximately half of the JIA patients had more or less distinctive changes in body function and/or structure after a disease duration of >15 years, fewer than 10% were severely disabled or handicapped. Because JIA often persists into adulthood, long-term followup and care are necessary.

Self-organized criticality as a fundamental property of neural systems

Abstract: The neural criticality hypothesis states that the brain may be poised in a critical state at a boundary between different types of dynamics. Theoretical and experimental studies show that critical systems often exhibit optimal computational properties, suggesting the possibility that criticality has been evolutionarily selected as a useful trait for our nervous system. Evidence for criticality has been found in cell cultures, brain slices, and anesthetized animals. Yet, inconsistent results were reported for recordings in awake animals and humans, and current results point to open questions about the exact nature and mechanism of criticality, as well as its functional role. Therefore, the criticality hypothesis has remained a controversial proposition. Here, we provide an account of the mathematical and physical foundations of criticality. In the light of this conceptual framework, we then review and discuss recent experimental studies with the aim of identifying important next steps to be taken and connections to other fields that should be explored.