Biomedical subjects

A Goldschmidt

Publications and source records attributed to A Goldschmidt.

17 recordsLinked to original sources

PubMed2006

Limits on the high-energy gamma and neutrino fluxes from the SGR 1806-20 giant flare of 27 December 2004 with the AMANDA-II detector.

On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the high-energy neutrino flux.

Journal Article↗

PubMed2004

Search for extraterrestrial point sources of neutrinos with AMANDA-II.

We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.

Journal Article↗

PubMed2003

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector.

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

Journal Article↗

PubMed2001

Measurement of the rate of nu(e) + d --> p + p + e(-) interactions produced by (8)B solar neutrinos at the Sudbury Neutrino Observatory.

Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).

Journal Article↗

PubMed2001

Parity violation observed in the beta decay of magnetically trapped 82Rb atoms.

Laser cooling and atomic trapping techniques have been employed to confine polarized 82Rb atoms ( T1/2 = 75 s) in a magnetic time-orbiting-potential (TOP) trap. We have observed the parity-violating correlation between the emitted positron momentum and the parent nuclear spin as a continuous function of angle and positron energy for this pure Gamow-Teller (GT) transition. These proof-of-principle measurements demonstrate the utility of exploring fundamental symmetries in a TOP trap and the steps required to improve sensitivity in the search for physics beyond the standard model.

Journal Article↗

PubMed2001

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice.

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

Journal Article↗

PubMed2001

Health informatics.

Health informatics is the development and assessment of methods and systems for the acquisition, processing and interpretation of patient data with the help of knowledge from scientific research. This definition implies that health informatics is not tied to the application of computers but more generally to the entire management of information in healthcare. The focus is the patient and the process of care. The apparent information overload and the imperfection of medical decision making motivate the use of information systems for medical decision support. Health informatics provides tools to control processes in healthcare, acquire medical knowledge and communicate information between all people and organisations involved with healthcare. Although the development of medical information systems may often lag behind the available possibilities, the technological state of the current medical information systems is better than it is generally held to be. Health informatics should help healthcare professionals to provide better and more cost-effective care and enable healthcare systems to be more efficient and to adapt better to our patients' needs. Health informatics may reshape the way we deliver care to meet the demands of the future.

Artificial Intelligence↗

PubMed2000

[CancerNet online--a contribution to improving oncologic management].

OBJECTIVE: We started the CancerNet project to evaluate the suitability of the internet to improve the quality of health care and the physician-patient relationship by offering worldwide access to high quality guidelines and standards. METHODS: Since early 1994 we have offered access to the National Cancer Institute's guidelines for current cancer therapy to physicians via WWW. These guidelines, which are provided by the NCI in accordance with the rules for evidence-based medicine, are accompanied by general information for non-professionals. Every month about 500 text-documents are HTML-encoded, linked together to about 10,000 abstracts available online as well as to MEDLINE. CancerNet is offered in English, Spanish, and German (only patient information) (http://www.meb.uni-bonn.de/cancernet/). RESULTS: From analyzing log files and user surveys in 1996, 1997, 1998, 1999, and 2000, we know that offering guidelines and patient information via the web fits most expectations of our users (physicians, health professionals, scientists, and laymen) on a high quality medical information service. Since 1994 nearly 2 million users, including more than 200,000 physicians, used our service. About 95% rated our service excellent or good.

Data Collection↗

PubMed2000

Gamma ray nuclear resonance absorption: an alternative method for in vivo body composition studies.

We have evaluated gamma ray nuclear resonance absorption (gamma-NRA) on nitrogen, a mature technology proposed and developed by Soreq NRC for detecting explosives, as an alternative to neutron activation for in vivo assaying of body nitrogen. The principles of the gamma-NRA method are outlined, and a test facility constructed at McMaster University's Accelerator Laboratory is described. The results of a feasibility study recently performed there on phantoms and animal tissue are presented and discussed. gamma-NRA is a full imaging technique that essentially constitutes element-specific absorptiometry--i.e., it can generate projections of the mass distribution for a specific element, along with a conventional radiograph of the patient. From the transmission profile of an individual scanned by 9.17 MeV gamma rays, local or whole body nitrogen content can be determined via the resonant attenuation undergone when the beam encounters regions of nitrogen concentration. The advantages of gamma-NRA over neutron activation are (a) radiation doses delivered to the body are at least one order of magnitude lower, thus allowing repeated measurements on individual patients and also rendering the method ethically acceptable for application to children; (b) gamma-NRA is inherently free from uncertainties related to nonuniform distributions of the element in question within the body; (c) it is applicable to patients of varying size and shape; and (d) it yields both nitrogen images and conventional radiographic images of the body.

Animals↗

PubMed2000

Practical aspects to realize data transfer between a patient administration mastersystem and clinical subsystems using ProtoGen/HL7.

At the Medizinische Einrichtungen Bonn the module IS-H of SAP R/3 is used for patient administration. All clinical subsystems will be provided with patient data using HL7 2.3 messages. These messages are generated from HCM messages a proprietary format of IS-H by means of a communication server. Interface application for subsystems which are not capable of processing HL7 messages are written using the open source C++ class library ProtoGen/HL7. First experiences and remaining problems are discussed.

Data Collection↗

PubMed2000

Differences in demographic data regarding physicians and patients in the US or abroad using a medically oriented Internet information service.

Since early 1994 we have offered access to the National Cancer Institute's guidelines for current cancer therapy to physicians via WWW. These guidelines, which are provided by the NCI in accordance with the rules for evidence-based medicine, are accompanied by general information for non-professionals. Since we launched this comprehensive cancer-related WWW information service in 1994, more than about 1 million customers retrieved documents from our CancerNet service via WWW (http://www.meb.uni-bonn.de/cancernet/). From user surveys in 1996, 1997, 1998, and 1999, we obtained demographic data about our users, their interests, and their opinions regarding this information service. The following analysis shows how this service was used over the years and includes some unexpected differences between users in the US, Europe, and developing countries.

Adult↗

PubMed1999

Worldwide telemedicine services based on distributed multimedia electronic patient records by using the second generation Web server hyperwave.

A distributed multimedia electronic patient record (EPR) is a central component of a medicine-telematics application that supports physicians working in rural areas of South America, and offers medical services to scientists in Antarctica. A Hyperwave server is used to maintain the patient record. As opposed to common web servers--and as a second generation web server--Hyperwave provides the capability of holding documents in a distributed web space without the problem of broken links. This enables physicians to browse through a patient's record by using a standard browser even if the patient's record is distributed over several servers. The patient record is basically implemented on the "Good European Health Record" (GEHR) architecture.

Antarctic Regions↗

PubMed1979