Search for charginos in e+e- interactions at sqrt(s) = 189 GeV

An update of the searches for charginos and gravitinos is presented, based on a data sample corresponding to the 158 pb^{-1} recorded by the DELPHI detector in 1998, at a centre-of-mass energy of 189 GeV. No evidence for a signal was found. The lower mass limits are 4-5 GeV/c^2 higher than those obtained at a centre-of-mass energy of 183 GeV. The (\mu,M_2) MSSM domain excluded by combining the chargino searches with neutralino searches at the Z resonance implies a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 31.0 GeV/c^2 for tan(beta) \geq 1.Comment: 22 pages, 8 figure

Hadronization properties of b quarks compared to light quarks in e+e- -> q qbar from 183 to 200 GeV

The DELPHI detector at LEP has collected 54 pb^{-1} of data at a centre-of-mass energy around 183 GeV during 1997, 158 pb^{-1} around 189 GeV during 1998, and 187 pb^{-1} between 192 and 200 GeV during 1999. These data were used to measure the average charged particle multiplicity in e+e- -> b bbar events, _{bb}, and the difference delta_{bl} between _{bb} and the multiplicity, _{ll}, in generic light quark (u,d,s) events: delta_{bl}(183 GeV) = 4.55 +/- 1.31 (stat) +/- 0.73 (syst) delta_{bl}(189 GeV) = 4.43 +/- 0.85 (stat) +/- 0.61 (syst) delta_{bl}(200 GeV) = 3.39 +/- 0.89 (stat) +/- 1.01 (syst). This result is consistent with QCD predictions, while it is inconsistent with calculations assuming that the multiplicity accompanying the decay of a heavy quark is independent of the mass of the quark itself.Comment: 13 pages, 2 figure

RF power and SiOxCyHz deposition efficiency in TEOS/O2 discharges for the corrosion protection of magnesium alloys

The effect of the applied voltage of 27.12 MHz TEOS/O 2/He discharges on the deposition process of SiO xC yH z thin films over rough as-cast Mg alloys was investigated by applying plasma diagnostics, surface characterization techniques and electrochemical impedance spectroscopy. The process efficiency in terms of power usage and deposition rate was calculated from plasma electrical and deposition rate measurements and was found to follow an inverse relation to the applied voltage, while saturating at higher voltages. Films with good substrate step coverage and free of cracks and structure failures were deposited at intermediate applied voltages and total power dissipation. As a consequence, the corrosion resistance of the films was optimized at the same conditions, indicating that in the case of no special pre-treatment of the Mg substrates, the corrosion performance is mainly determined by the SiO xC yH z adhesion to the substrate rather than the chemical composition of the film

Uterine sarcomas: Therapeutic approach, prognostic and epidemiologic factors evaluation: A prospective clinical study of 36 cases

Introduction: The purpose of the present prospective study was to evaluate prognosis (survival, recurrence rates) and other prognostic and epidemiologic factors regarding uterine sarcomas, after the application of a specific therapeutic protocol. Patients or Methods: This protocol included radical cytoreduction surgery and adjuvant chemotherapy with multiple agents (ifosfamide, etoposide, doxorubicin, MESNA). The study included 36 patients with no recessive or progressive disease after surgery. 22 of the cases (61%) were mixed mullerian tumors, 10 (28%) were leiomyosarcomas and 4 (11%) other types. Results: Mean age of appearance was 63.5 years for mixed mullerian tumors, 52.8 for leiomyosarcoma and 38.7 for other types, a difference that was significant (p = 0.008). Additionally, the proportion of premenopausal patients was significantly increased among tumors with other histological types. After a median 61.5 months follow-up, we registered as median survival rate 46.8 months and as median disease free period 29.5 months in total. This clinical outcome is considered as satisfactory, taking in mind the tumors' aggressiveness. Per histological type, median survival rate was 46.8 months for mixed mullerian tumors and 44.1 months for leiomyosarcoma, a difference which was not significant. On the contrary, patients with leiomyosarcoma relapsed more rapidly than patients with mixed mullerian tumors and other types and this difference was significant (p = 0.01).Therefore, the leiomyosarcoma appears to be the most aggressive histologic type among uterine sarcomas. Stage at presentation (early I, II vs. advanced III, IV) was not proved to be of statistical significance regarding survival and recurrence rates, obviously because of the relatively high survival and disease free period rates achieved among advanced stage patients, possibly due to recurrence successful chemotherapy treatment after radical surgery. In mixed mullerian tumors vascular invasion and the presence of heterologous elements does not affect clinical outcome, although we observed a clear tendency for a worse prognosis in the last case. Conclusions: Despite tumor's aggressiveness and low survival and disease free period rates, a complex therapeutic protocol application which includes radical surgical cytoreduction and adjuvant postoperative chemotherapy with multiple therapeutic regiments, may contribute to higher survival and recurrence free rates. Adjuvant radiotherapy doesn't seem to improve clinical outcome. Leiomyosarcoma seems to be the most aggressive histological type among female genital tract sarcomas, since it rapidly relapses. © Georg Thieme Verlag KG Stuttgart

The optical module for the NESTOR neutrino telescope

NESTOR is a deep-sea water Cherenkov neutrino detector now under construction for deployment in the Mediterranean off Greece. Its key component is an optical module employing a photomultiplier tube with a 15 in. hemispherical photocathode in a transparent glass pressure housing. Extensive tests have been made on the sensitivity, uniformity, time resolution, noise rates and mechanical properties of the module: several test deployments have been made at sea. © 2002 Elsevier Science B.V. All rights reserved

Investment Portfolio Optimisation Model Based on Stocks Investment Attractiveness

Firm's performance and potential return on investments in its stocks are determined by many factors. However, most of portfolio optimisation methods are oriented to decision- making based on stock price changes in the past. Recent financial crisis has showed that often the biggest downfall in the period of crisis is experienced by stocks, which had the biggest growth before crisis. So decision- making based on stock price tendencies analysis by ignoring fundamental factors can be inefficient. The variety of MCDM methods was briefly described and their application possibilities for portfolio optimisation were evaluated in the article. The basic portfolio selection model, based on stocks investment attractiveness, was introduced. Particular model application solutions to stocks investment attractiveness evaluation and direct portfolio optimisation stages were proposed. The pilot research was carried out, the results of which showed that proposed model enables gaining better results than comparative Markowitz and equal weights portfolios

Electroweak parameters of the z0 resonance and the standard model

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