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I Braun

Publications and source records attributed to I Braun.

At least 19 recordsLinked to original sources
PubMed2006

HESS observations of the galactic center region and their possible dark matter interpretation.

The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin.

Journal Article↗
PubMed2006

Fast variability of tera-electron volt gamma rays from the radio galaxy M87.

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.

Journal Article↗
PubMed2006

Short-term preoperative radiotherapy in rectal cancer patients leads to a reduction of the detectable number of lymph nodes in resection specimens.

BACKGROUND AND AIMS: The Union Internationale Contre le Cancer and American Joint Committee on Cancer classification propose that pN(0)-classified colorectal lymphadenectomy specimens will ordinarily include 12 or more tumor-negative lymph nodes. We performed a clinical trial to investigate whether a short-term preoperative radiotherapy (5x5 Gy) leads to a reduction of the number of lymph nodes in rectal cancer specimens after total and partial mesorectal excision (TME and PME, respectively). MATERIALS AND METHODS: Within a 5-year period, 28 (15%) of 148 rectal cancer patients underwent hypofractionated preoperative radiotherapy in this monocenter study, whereas 120 patients (85%) underwent TME/PME surgery alone. The main criterion was the number of lymph nodes in TME/PME specimens. We used a stratified one-sided Wilcoxon-Mann-Whitney test to test for a significant difference in the number of lymph nodes, stratifying for tumor location and postoperative tumor stage. Patients who were suspected of having any alterations in the number of pelvic lymph nodes were excluded from the study. RESULTS: Fewer lymph nodes were detected in the TME/PME specimens of patients who received hypofractionated preoperative radiotherapy compared to patients who underwent TME/PME surgery alone (12 detectable lymph nodes vs 15; p=0.0005). Tumor location (p=0.095) and tumor stage (p=0.093) did not significantly influence the number of lymph nodes in this study. CONCLUSIONS: We conclude that a 5x5 Gy short-term preoperative radiotherapy leads to a reduction in the number of lymph nodes in TME/PME specimens. Because neoadjuvant therapy in rectal cancer for T(2) and T(3) tumors has advanced a new therapeutic standard procedure, in the future, less lymph nodes will be detected in TME/PME specimens. This might influence the required number of lymph nodes in current staging systems for rectal cancer in the future.

Combined Modality Therapy↗
PubMed2006

A low level of extragalactic background light as revealed by gamma-rays from blazars.

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the 'first stars', which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the gamma-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of gamma-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources-in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to gamma-rays than previously thought.

Journal Article↗
PubMed2006

Discovery of very-high-energy gamma-rays from the Galactic Centre ridge.

The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago.

Journal Article↗
PubMed2005

Discovery of very high energy gamma rays associated with an x-ray binary.

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Journal Article↗
PubMed2005

A new population of very high energy gamma-ray sources in the Milky Way.

Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (HESS) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or x-ray counterpart and may be representative of a new class of "dark" nucleonic cosmic ray sources.

Journal Article↗
PubMed1999

Accelerated fractionated proton/photon irradiation to 90 cobalt gray equivalent for glioblastoma multiforme: results of a phase II prospective trial.

OBJECT: After conventional doses of 55 to 65 Gy of fractionated irradiation, glioblastoma multiforme (GBM) usually recurs at its original location. This institutional phase II study was designed to assess whether dose escalation to 90 cobalt gray equivalent (CGE) with conformal protons and photons in accelerated fractionation would improve local tumor control and patient survival. METHODS: Twenty-three patients were enrolled in this study. Eligibility criteria included age between 18 and 70 years, Karnofsky Performance Scale score of greater than or equal to 70, residual tumor volume of less than 60 ml, and a supratentorial, unilateral tumor. Actuarial survival rates at 2 and 3 years were 34% and 18%, respectively. The median survival time was 20 months, with four patients alive 22 to 60 months postdiagnosis. Analysis by Radiation Therapy Oncology Group prognostic criteria or Medical Research Council indices showed a 5- to 11-month increase in median survival time over those of comparable conventionally treated patients. All patients developed new areas of gadolinium enhancement during the follow-up period. Histological examination of tissues obtained at biopsy, resection, or autopsy was conducted in 15 of 23 patients. Radiation necrosis only was demonstrated in seven patients, and their survival was significantly longer than that of patients with recurrent tumor (p = 0.01). Tumor regrowth occurred most commonly in areas that received doses of 60 to 70 CGE or less; recurrent tumor was found in only one case in the 90-CGE volume. CONCLUSIONS: A dose of 90 CGE in accelerated fractionation prevented central recurrence in almost all cases. The median survival time was extended to 20 months, likely as a result of central control. Tumors will usually recur in areas immediately peripheral to this 90-CGE volume, but attempts to extend local control by enlarging the central volume are likely to be limited by difficulties with radiation necrosis.

Actuarial Analysis↗
PubMed1999

Pediatric movement disorders.

Movement disorders in children encompass disorders of motor control--both hyperkinetic (excessive movement) and hypokinetic (decreased movement). This article focuses on the hyperkinetic movement disorders, particularly tremor, Wilson's disease, dystonia, tics and Tourette syndrome, chorea, myoclonus, neuroleptic-induced movement disorders, and psychogenic movement disorders. Phenomenology of the disorders as well as clinical presentation, basic pathophysiology, genetics, and treatment are discussed.

Antipsychotic Agents↗
PubMed1988

Investigations on biochemical properties of milk-clotting enzymes.

The properties of proteolytic enzymes produces from calf maws and from an Ascomycete were studied. Both milk-clotting proteases have their optimum activity at pH 5.2 and 45 degrees C. The microbiological rennin has a second maximum activity at pH 3.5 and 55 degrees C. Temperatures above 55 degrees C cause a rapid decrease of activity. The behaviour of enzyme activity is similar with varying substrate and enzyme concentrations. However, increasing amounts of enzyme in ratio to the substrate lead to reaction rates of the calf rennin differing clearly from that of the microbiological rennet complex.

Animals↗
PubMed1980

[Bronchitis--a social medical study (author's transl)].

1. Every third or fourth patient visiting an outpatients department for pulmonary diseases was found to have chronic bronchitis. 2. Twice as many manual workers as other workers suffer from chronic bronchitis. This difference seems to be related to the dusty conditions to which manual workers are exposed. Manual workers in clean conditions have the same proportion of chronic bronchitis as non manual workers. 3. Up to the age of sixty there is no difference in the incidence of chronic bronchitis in male and female patients. Above the age of sixty the incidence in males exceeds than in females. 4. No difference between male and female patients up to the age of sixty years is also in regard of the combination of chronic bronchitis and pulmonary emphysema.

Adult↗
PubMed1970

Administration of amantadine for the prevention of Hong Kong influenza.

The prophylactic effectiveness of amantadine against A2/Hong Kong influenza was investigated in the course of a double-blind trial in Braşov, Romania, during an epidemic due to the Hong Kong virus that started there in March 1969.Altogether 215 subjects were included in the trial; 112 received 100 mg of amantadine twice daily for 20 days and the remaining 103 received inert placebo tablets. Of the amantadine-treated group, 2 had clinical symptoms diagnosed as influenza (1 of these was a doubtful diagnosis), whereas 20 (1 doubtful) of the placebo group had such symptoms. No case with both clinical symptoms and serologically confirmed influenza (>/=4-fold increase in haemagglutination-inhibition titre) occurred among 77 amantadine-treated subjects for whom paired sera were available but there were 13 such cases among the 74 placebo subjects with paired sera. These differences are statistically highly significant. No serious side-effects were recorded.The authors conclude that amantadine was highly effective in preventing overt disease and discuss indications that suggest that it did not interfere with the development of immunity in persons treated during the incubation period.

Adolescent↗