CERN PS laser ion source development

CERN, together with ITEP and TRINITI (Russia), is developing a CO2 laser ion source. The key design parameters are: 1.4 1010 ions of Pb25+ in a pulse of 5.5 ms, with a 4-rms emittance of 0.2 10-6 rad m, working at a repetition rate of 1 Hz. This device is considered as one candidate source for LHC heavy ion operation. The status of the laser development, the experimental set-up of the source consisting of the target area and its illumination, the plasma expansion area and extraction, beam transport and ion pre-acceleration by an RFQ, will be given

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

Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

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

Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP

Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of the production of these particles is found. Hence, lower mass limits for both kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is found to be greater than 71.5 GeV/c^2. In the search for long-lived stau, masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10 to 150 \eVcc . Combining this search with the searches for stable heavy leptons and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc may be set for the stau mas

ПРИМЕНЕНИЕ БИОПРОТЕЗОВ В ХИРУРГИИ МИТРАЛЬНЫХ ПОРОКОВ: ВОЗМОЖНОСТИ ОТКАЗА ОТ АНТИКОАГУЛЯНТНОЙ ТЕРАПИИ

Aim. To evaluate the clinical efficacy of gradual sinus rhythm restoration, including the bioprosthetic mitral valve replacement combined with maze radiofrequency ablation, external cardioversion and catheter ablation.Methods.102 medical records of patients with mitral valve disease and long-standing atrial fibrillation (4,7±2,7 years) were restrospectively reviewed. Maze procedure was performed under extracorporeal circulation before the mitral valve replacement. The endpoints were monitored at the day of surgery, at discharge, and 3, 6 and 12 months after surgery.Results.Sinus rhythm was recorded in 65.7% of patients at discharge from the hospital. The completeness of the follow-up was 80.4%. Steady regular rhythm was maintained in 64.6 % of patients in the study group. Other patients (35.4%) underwent cardioversion with the efficacy rate of 41.4%. Anticoagulation therapy was withdrawn in 65.9% of patients three months after surgery. 18.3% of patients with symptomatic arrhythmia underwent catheter ablation, which allowed to restore sinus rhythm in 73.3% of cases. Sinus rhythm was recorded in 92.7% of cases within the 1-year follow-up. Importantly, 79.3% of patients were discontinued of indirect anticoagulants. Conclusion. Discontinuation of indirect anticoagulants proved its beneficial effects and safety on the restoration of sinus rhythm in patients after bioprosthetic mitral valve replacement.Цель. Оценка клинической эффективности последовательной стратегии восстановления синусового ритма (СР), включающей протезирование митрального клапана биопротезом с одномоментной радиочастотной аблацией по методике «лабиринт», наружную электроимпульсную терапию и катетерную аблацию.Материалы и методы. Проанализированы результаты хирургического лечения 102 пациентов с митральными пороками сердца и продолжительным анамнезом фибрилляции предсердий (4,7±2,7лет). Радиочастотную аблацию «лабиринт» выполняли в условиях искусственного кровообращения до этапа биопротезирования митрального клапана. Контрольные точки исследования – день операции, день выписки из стационара, три, шесть и 12 месяцев после вмешательства.Результаты. При выписке из клиники СР регистрировали у 65,7% пациентов. Полнота наблюдения на амбулаторном этапе составила 83,7%. Устойчивый правильный ритм в наблюдаемой группе сохранялся в 64,6% случаев. Остальным пациентам (35,4%) проведена электроимпульсная терапия, эффективность которой составила 41,4%. Спустя три месяца после оперативного вмешательства антикоагулянтная терапия отменена 65,9% пациентов. 18,3% пациентов с симптомной аритмией выполнена повторная катерная аблация, в результате которой в 73,3% случаев восстановлен СР. К концу годового этапа СР регистрировали в 92,7% случаев, при этом у 79,3% пациентов были отменены непрямые антикоагулянты.Заключение.Продемонстрирована высокая эффективность и безопасность предложенной стратегии восстановления СР при использовании биопротезов в хирургии митральных пороков с позиции возможности отказа от непрямых антикоагулянтов

ОСОБЕННОСТИ ФУНКЦИОНАЛЬНОГО СОСТОЯНИЯ СТРУКТУР ГОЛОВНОГО МОЗГА У ВИЧ-ИНФИЦИРОВАННЫХ ПАЦИЕНТОВ

HIV-associated neurocognitive disorders are on the second place after immune system injury in HIV infection. Despite the large amount of studies, their mechanisms remain unclear especially in the subclinical stage. The purpose of our research was to study changes of brain functional state in HIV patients in different stages of the disease and revealing the early and probably prognostic features (characteristics) of subclinical neurocognitive disorders on the basis of combined analysis of the positron emission tomography (PET) and magnetic resonance spectroscopy (MRS). The obtained data demonstrated local metabolic disturbances in gray and white matter in the early stages of HIV infection. These findings raise the question about the early implication of the highly active anti-retrovirus therapy (HAART) and neuroprotectors. The abundance of the metabolic changes increases with the progression of HIV clinical symptoms. Revealed characteristics of the glucose metabolic pattern in HIV patients and threshold values of the basic metabolites ratios in MRS could be used as a predictors of the further neurocognitive disorders.Поражения нервной системы при ВИЧ-инфекции стоят на втором месте после иммунной. Их механизмы, несмотря на большое число исследований, в том числе различными методами лучевой диагностики, на данный момент остаются недостаточно ясными, особенно когда речь идет о процессах, происходящих на субклинической стадии. Целью работы было изучение изменений функционального состояния головного мозга у ВИЧ-инфицированных пациентов на разных стадиях развития болезни, в том числе на ранних, при отсутствии неврологической симптоматики и когнитивных нарушений на основе сочетанного анализа данных позитронно-эмиссионной томографии (ПЭТ) и магнитно-резонансной спектроскопии (МРС). Полученные нами данные свидетельствуют об имеющихся уже на ранней стадии ВИЧ-инфицирования локальных и регионарных метаболических нарушениях в сером и белом веществе головного мозга. Распространенность метаболических изменений при прогрессировании ВИЧ-инфекции увеличивается. Полученные характеристики паттерна распределения скорости метаболизма глюкозы у ВИЧ-инфицированных пациентов и пороговые значения соотношений основных метаболитов по данным МРС могут быть использованы для разработки диагностических критериев - предикторов развития нейрокогнитивных нарушений. Полученные данные соответствуют представлениям о целесообразности раннего использования высокоактивной антиретровирусной терапии (ВААРТ) и необходимости применения нейропротекторов

The NOMAD experiment at the CERN SPS

The NOMAD experiment is a short base-line search for $\nu_{\mu}\rightarrow \nu_{\tau}$ oscillations in the CERN neutrino beam. The $\nu_{\tau}$'s are searched for through their charged-current interactions followed by the observation of the resulting $\tau^{-}$ through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors, and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction of individual particles is demonstrated through the ability of NOMAD to observe K$^0_{\rm s}$'s, $\Lambda^0$'s and $\pi^0$'s. Finally, the observation of $\tau^{-}$ through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed