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1.
Phys Rev Lett ; 129(1): 011806, 2022 Jul 01.
Article in English | MEDLINE | ID: mdl-35841544

ABSTRACT

We report on the direct search for cosmic relic neutrinos using data acquired during the first two science campaigns of the KATRIN experiment in 2019. Beta-decay electrons from a high-purity molecular tritium gas source are analyzed by a high-resolution MAC-E filter around the end point at 18.57 keV. The analysis is sensitive to a local relic neutrino overdensity ratio of η<9.7×10^{10}/α (1.1×10^{11}/α) at a 90% (95%) confidence level with α=1 (0.5) for Majorana (Dirac) neutrinos. A fit of the integrated electron spectrum over a narrow interval around the end point accounting for relic neutrino captures in the tritium source reveals no significant overdensity. This work improves the results obtained by the previous neutrino mass experiments at Los Alamos and Troitsk. We furthermore update the projected final sensitivity of the KATRIN experiment to η<1×10^{10}/α at 90% confidence level, by relying on updated operational conditions.

2.
Phys Rev Lett ; 126(9): 091803, 2021 Mar 05.
Article in English | MEDLINE | ID: mdl-33750167

ABSTRACT

We report on the light sterile neutrino search from the first four-week science run of the KATRIN experiment in 2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are analyzed by a high-resolution MAC-E filter down to 40 eV below the endpoint at 18.57 keV. We consider the framework with three active neutrinos and one sterile neutrino. The analysis is sensitive to the mass, m_{4}, of the fourth mass state for m_{4}^{2}≲1000 eV^{2} and to active-to-sterile neutrino mixing down to |U_{e4}|^{2}≳2×10^{-2}. No significant spectral distortion is observed and exclusion bounds on the sterile mass and mixing are reported. These new limits supersede the Mainz results for m_{4}^{2}≲1000 eV^{2} and improve the Troitsk bound for m_{4}^{2}<30 eV^{2}. The reactor and gallium anomalies are constrained for 100<Δm_{41}^{2}<1000 eV^{2}.

3.
Mol Psychiatry ; 17(12): 1180-5, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22392033

ABSTRACT

Large-scale collaborative research will be a hallmark of future psychiatric genetic research. Ideally, both academic and non-academic institutions should be able to participate in such collaborations to allow for the establishment of very large samples in a straightforward manner. Any such endeavor requires an easy-to-implement information technology (IT) framework. Here we present the requirements for a centralized framework and describe how they can be met through a modular IT toolbox.


Subject(s)
Biological Psychiatry/methods , Biological Psychiatry/trends , Cooperative Behavior , Genetic Research , Medical Informatics/methods , Medical Informatics/trends , Humans , Models, Organizational , Software
4.
Appl Clin Inform ; 2(1): 116-27, 2011.
Article in English | MEDLINE | ID: mdl-23616864

ABSTRACT

OBJECTIVE: Data from clinical care is increasingly being used for research purposes. The i2b2 platform has been introduced in some US research communities as a tool for data integration and querying by clinical users. The purpose of this project was to assess the applicability of i2b2 in Germany regarding use cases, functionality and integration with privacy enhancing tools. METHODS: A set of four research usage scenarios was chosen, including the transformation and import of ontology and fact data from existing clinical data collections into i2b2 v1.4 instances. Query performance was measured in comparison to native SQL queries. A setup and administration tool for i2b2 was developed. An extraction tool for CDISC ODM data was programmed. Interfaces for the TMF privacy enhancing tools (PID Generator, Pseudonymization Service) were implemented. RESULTS: Data could be imported in all tested scenarios from various source systems, including the generation of i2b2 ontology definitions. The integration of TMF privacy enhancing tools was possible without modification of the platform. Limitations were found regarding query performance in comparison to native SQL and certain temporal queries. CONCLUSIONS: i2b2 is a viable platform for data query tasks in use cases typical for networked medical research in Germany. The integration of privacy enhancing tools facilitates the use of i2b2 within established data protection concepts. Entry barriers should be lowered by providing tools for simplified setup and import of medical standard formats like CDISC ODM.

5.
Methods Inf Med ; 49(6): 601-7, 2010.
Article in English | MEDLINE | ID: mdl-20644898

ABSTRACT

BACKGROUND: The data protection requirements matured in parallel to new clinical tests generating more personal data since the 1960s. About ten years ago it was recognized that a generic data protection scheme for medical research networks is required, which reinforces patient rights but also allows economically feasible medical research compared to "hand-carved" individual solutions. OBJECTIVES: To give recommendations for more efficient IT infrastructures for medical research networks in compliance with data protection requirements. METHODS: The IT infrastructures of three medical research networks were reviewed with respect to the relevant data management modules. Recommendations are derived to increase cost efficiency in research networks assessing the consequences of a service provider approach without lowering the data protection level. RESULTS: The existing data protection schemes are very complex. Smaller research networks cannot afford the implementation of such schemes. Larger networks struggle to keep them sustainable. Due to a modular redesign in the medical research network community, a new approach offers opportunities for an efficient sustainable IT infrastructure involving a service provider concept. For standard components 70-80% of the costs could be cut down, for open source components about 37% over a three-year period. CONCLUSIONS: Future research networks should switch to a service-oriented approach to achieve a sustainable, cost-efficient IT infrastructure.


Subject(s)
Biomedical Research , Computer Communication Networks , Computer Security , Databases as Topic , Program Evaluation
6.
Phys Rev Lett ; 94(16): 162001, 2005 Apr 29.
Article in English | MEDLINE | ID: mdl-15904214

ABSTRACT

Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.

7.
Phys Rev Lett ; 93(3): 032003, 2004 Jul 16.
Article in English | MEDLINE | ID: mdl-15323817

ABSTRACT

For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] microb with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.

8.
Phys Rev Lett ; 92(7): 071102, 2004 Feb 20.
Article in English | MEDLINE | ID: mdl-14995836

ABSTRACT

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.

9.
Phys Rev Lett ; 91(19): 192001, 2003 Nov 07.
Article in English | MEDLINE | ID: mdl-14611575

ABSTRACT

To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb.

10.
Phys Rev Lett ; 88(23): 232002, 2002 Jun 10.
Article in English | MEDLINE | ID: mdl-12059355

ABSTRACT

The helicity dependence of the gamma-->p-->-->ppi(0) reaction has been measured for the first time in the photon-energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the D13(1520) resonance and are used to determine its helicity amplitudes.

11.
Phys Rev Lett ; 84(26 Pt 1): 5950-4, 2000 Jun 26.
Article in English | MEDLINE | ID: mdl-10991096

ABSTRACT

The helicity dependence of the single pion photoproduction on the proton has been measured in the energy range from 200 to 450 MeV for the first time. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a frozen-spin target. The data obtained provide new information for multipole analyses of pion photoproduction and determine the main contributions to the Gerasimov-Drell-Hearn sum rule and the forward spin polarizability gamma(0).

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