A non-chiral extension of the standard model with mirror fermions

The difficulties of defining chiral gauge theories non-perturbatively suggest a vector-like extension of the standard model with three mirror fermion families. Some phenomenological implications of such an extension are discussed.Comment: latex, 6 pages, 1 figure with epsfig. Talk given at the workshop "Beyond the Standard Model V", Balholm, Norway, May 199

Numerical simulation with light Wilson-quarks

The computational cost of numerical simulations of QCD with light dynamical Wilson-quarks is estimated by determining the autocorrelation of various quantities. In test runs the expected qualitative behaviour of the pion mass and coupling at small quark masses is observed.Comment: 5 pages, 3 figures, to appear in the Proceedings of SEWM, Heidelberg, 200

Simulating the Electroweak Phase Transition in the SU(2) Higgs Model

Numerical simulations are performed to study the finite temperature phase transition in the SU(2) Higgs model on the lattice. In the presently investigated range of the Higgs boson mass, below 50 GeV, the phase transition turns out to be of first order and its strength is rapidly decreasing with increasing Higgs boson mass. In order to control the systematic errors, we also perform studies of scaling violations and of finite volume effects.Comment: 46 pages with 16 figures, DESY-94-15

Numerical simulation tests with light dynamical quarks

Two degenerate flavours of quarks are simulated with small masses down to about one fifth of the strange quark mass by using the two-step multi-boson (TSMB) algorithm. The lattice size is 8^3 x 16 with lattice spacing about 0.27fm which is not far from the N_t=4 thermodynamical cross-over line. Autocorrelations of different physical quantities are estimated as a function of the quark mass. The eigenvalue spectra of the Wilson-Dirac operator are investigated.Comment: 14 pages, 7 figures, uses svjour.cls; mistake in the autocorrelation of the pion mass corrected, version accepted for publication on Eur. Phys. J.

Case report: BRCA in the Ashkenazi population: are current testing guidelines too exclusive?

The BRCA1/2 genes account for a significant portion of hereditary breast and ovarian cancers and they are especially prevalent in the Ashkenazi Jewish population. Women who have a mutation can prevent breast and ovarian cancer with surgical intervention. We describe an Ashkenazi Jewish patient who illustrates that current testing criteria are too restrictive, particularly for this population of patients. The patient's sister was diagnosed with breast cancer at age 33; however, she was not a mutation carrier. Based on practice guidelines, the patient was not recommended genetic testing. She subsequently underwent direct-to-consumer (DTC) testing and discovered that she was a mutation carrier. This case demonstrates the need for clinicians to be aware of the higher prevalence of BRCA mutations in the Ashkenazi population. It also exemplifies the need to involve medical professionals, including genetic counselors, in the dissemination of DNA test results

Fear of the unknown: a pre-departure qualitative study of Turkish international students

This paper presents findings from eleven in-depth interviews with Turkish undergraduate students, who were, by the time of data collection, about to spend a semester at a European university under the Erasmus exchange scheme. The students all agreed to be interviewed about their feelings about studying in a foreign culture, and were found to be anxious prior to departure about the quality of accommodation in the new destination, their language ability and the opportunity to form friendships. Fears were expressed about possible misconceptions over Turkey as a Muslim and a developing country. Suggestions are made for HEI interventions to allay student travellers’ concerns

SCHEME FOR GENERATING AND TRANSPORTING THZ RADIATION TO THE X-RAY EXPERIMENTAL HALL AT THE EUROPEAN XFEL

Abstract We consider generation of THz radiation from the spent electron beam downstream of the SASE2 undulator in the electron beam dump area. The THz output must propagate at least for 250 meters through the photon beam tunnel to the experimental hall to reach the SASE2 X-ray hutches. We propose to use an open beam waveguide such as an iris guide as transmission line. In order to efficiently couple radiation into the iris transmission line, generation of the THz radiation pulse can be performed directly within the iris guide. The line transporting the THz radiation to the SASE2 X-ray hutches introduces a path delay of about 20 m. Since THz pump/X-ray probe experiments should be enabled, we propose to exploit the European XFEL baseline multi-bunch mode of operation, with 222 ns electron bunch separation, in order to cope with the delay between THz and X-ray pulses. We present start-to-end simulations for 1 nC bunch operation-parameters, optimized for THz pump/X-ray probe experiments. Detailed characterization of the THz and SASE X-ray radiation pulses is performed. Highly focused THz beams will approach the high field limit of 1 V/atomic size