Impact of Uncertainties in Hadron Production on Air-Shower Predictions

At high energy, cosmic rays can only be studied by measuring the extensive air showers they produce in the atmosphere of the Earth. Although the main features of air showers can be understood within a simple model of successive interactions, detailed simulations and a realistic description of particle production are needed to calculate observables relevant to air shower experiments. Currently hadronic interaction models are the main source of uncertainty of such simulations. We will study the effect of using different hadronic models available in CORSIKA and CONEX on extensive air shower predictions.Comment: 12 pages, 6 figures, to appear in the proceedings of International Conference on Interconnection between High Energy Physics and Astroparticle Physics: From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 Sep 200

Time-Reversal Violating Schiff Moment of 225Ra

We use the Skyrme-Hartree-Fock method, allowing all symmetries to be broken, to calculate the time-reversal-violating nuclear Schiff moment (which induces atomic electric dipole moments) in the octupole-deformed nucleus 225Ra. Our calculation includes several effects neglected in earlier work, including self consistency and polarization of the core by the last nucleon. We confirm that the Schiff moment is large compared to those of reflection-symmetric nuclei, though ours is generally a few times smaller than recent estimates.Comment: Typos corrected, references added, minor changesin text. Version to appear in PRC. 10 pages, 4 figure

Antenna servo control system characterization: Rate loop analysis for 34-m antenna at DSS 15

The elevation and azimuth servo rate loops at the 34-m High Efficiency Deep Space Station 15 (DSS 15) are described. Time and frequency response performance criteria were measured. The results are compared to theoretically deduced performance criteria. Unexpected anomalies in the frequency response are observed and identified

Ab Initio Treatment of Collective Correlations and the Neutrinoless Double Beta Decay of 48^{48}Ca

Working with Hamiltonians from chiral effective field theory, we develop a novel framework for describing arbitrary deformed medium-mass nuclei by combining the in-medium similarity renormalization group with the generator coordinate method. The approach leverages the ability of the first method to capture dynamic correlations and the second to include collective correlations without violating symmetries. We use our scheme to compute the matrix element that governs the neutrinoless double beta decay of $^{48}$Ca to $^{48}$Ti, and find it to have the value $0.61$, near or below the predictions of most phenomenological methods. The result opens the door to ab initio calculations of the matrix elements for the decay of heavier nuclei such as $^{76}$Ge, $^{130}$Te, and $^{136}$Xe.Comment: 6 pages, 4 figures and 1 table. supplementary material included. version to be publishe

Population-based patient care study for breast cancer

Background: Different approaches for an effective quality management are funded by the Ministry of Health to verify, to assess and, if necessary to optimize the quality of health care using the tracer diagnoses of breast, rectal, and lung cancer in eight regions in Germany. The conception of these observational studies and initial findings are shown here, using breast cancer in the region of Munich (population 2.4 million) as an example. Patients and Methods: The study started on April 1, 1996. The recruitment phase for all primary boast cancer patients in this region is planned for 2 years with a 3-5-year follow-up. Established documentation sheets are used to document basic medical information of each patient, along with the original reports (pathology: radiotherapy, doctors' reports, etc.), follow-up reports and quality of life questionnaires (QLQ, including the EORTC QLQ C30). Results: In 1996, the Munich region has a crude incidence of 125/100,000 women (world standard 71.5). After almost complete documentation the incidence is 10-15% higher. In the period from April 1 1996 to June 30, 1997 1,360 patients have been recruited into the study. 79% of the patients were 50 years of age or older. pT stages are distributed as follows: pTIS 5%, pT1 54%, pT2 32%, pT3 4%, pT4 6%. 4.5% had primary metastases. Breast-conserving therapy (BCT) was performed in 57% of patients. Five of the 46 departments involved recruited more than 50 patients each within these 14 months. These larger departments treat 59% of all patients. The proportion of older patients and pT4 stages is significantly higher in the smaller departments. BCT is performed significantly more often in the larger departments. First results of quality of life show dependencies on age, but no differences between mastectomy and BCT 3 months after operation. Not only the addressed patients (response rate to QLQ over 80%) but also almost all hospitals and many physicians are milling to support and to partake in quality assurance. 35 hospitals, 46 surgical departments. 80 heads of department and surgically: active general practioners, 330 general practioners. 7 radiotherapy departments, and 13 pathology departments have so far documented for this study. Conclusions: An effective quality management in oncology needs a modern cancer registry which uses documentation sheets as well as original reports and organizes the complicated infrastructure for an interdisciplinary cooperation. To be able to evaluate the health care reality it is necessary to carry out a data analysis and assess each individual case. A feedback of the results have to be available for each physician and each department. The cost of this information management is approximately 0.3% of the health care cost for this group of patients

Controlled exchange interaction for quantum logic operations with spin qubits in coupled quantum dots

A two-electron system confined in two coupled semiconductor quantum dots is investigated as a candidate for performing quantum logic operations on spin qubits. We study different processes of swapping the electron spins by controlled switching on/off the exchange interaction. The resulting spin swap corresponds to an elementary operation in quantum information processing. We perform a direct time evolution simulations of the time-dependent Schroedinger equation. Our results show that -- in order to obtain the full interchange of spins -- the exchange interaction should change smoothly in time. The presence of jumps and spikes in the corresponding time characteristics leads to a considerable increase of the spin swap time. We propose several mechanisms to modify the exchange interaction by changing the confinement potential profile and discuss their advantages and disadvantages

Possible origin of the 0.5 plateau in the ballistic conductance of quantum point contacts

A non-equilibrium Green function formalism (NEGF) is used to study the conductance of a side-gated quantum point contact (QPC) in the presence of lateral spin-orbit coupling (LSOC). A small difference of bias voltage between the two side gates (SGs) leads to an inversion asymmetry in the LSOC between the opposite edges of the channel. In single electron modeling of transport, this triggers a spontaneous but insignificant spin polarization in the QPC. However, the spin polarization of the QPC is enhanced substantially when the effect of electron-electron interaction is included. The spin polarization is strong enough to result in the occurrence of a conductance plateau at 0.5G0 (G0 = 2e2/h) in the absence of any external magnetic field. In our simulations of a model QPC device, the 0.5 plateau is found to be quite robust and survives up to a temperature of 40K. The spontaneous spin polarization and the resulting magnetization of the QPC can be reversed by flipping the polarity of the source to drain bias or the potential difference between the two SGs. These numerical simulations are in good agreement with recent experimental results for side-gated QPCs made from the low band gap semiconductor InAs