Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

EFEITO ANALGÉSICO DO BUTORFANOL NA DOR SOMÁTICA EM GATOS ANESTESIADOS COM PROPOFOL ANALGESIC EFFECT OF BUTORPHANOL ON SOMATIC PAIN IN CATS ANESTHETIZED WITH PROPOFOL

O propofol é um agente anestésico intravenoso usado para indução e manutenção da anestesia, mas produz analgesia limitada, havendo a necessidade do uso concomitante de analgésicos. Avaliou-se o efeito analgésico do butorfanol na dor somática em gatos anestesiados com doses fracionadas de propofol. Foram utilizados 16 animais, distribuídos aleatoriamente em dois grupos. Os animais do grupo controle foram pré-tratados com 0,2mg/kg de acepromazina por via IM e, após 15 minutos, receberam 6mg/kg de propofol por via IV. Os animais do grupo tratamento foram pré-medicados com uma combinação de acepromazina (0,2mg/kg) e butorfanol (0,8mg/kg), administrados na mesma seringa por via IM, e, após 15 minutos, receberam 6mg/kg de propofol por via IV. Em ambos os grupos, a manutenção da anestesia foi feita com administrações de propofol, na dose de 3mg/kg, por via IV, sempre que necessário, durante 60 minutos. A necessidade de readministração de propofol foi verificada pela resposta apresentada ao pinçamento cutâneo, através de uma pinça de Kocher. Avaliaram-se também as freqüências cardíaca e respiratória, pressão arterial média, saturação de oxiemoglobina e temperatura retal. A administração de butorfanol causou apenas redução nas freqüências cardíaca e respiratória e na saturação de oxiemoglobina, em comparação com o grupo controle,sem exercer influência significativa sobre o período hábil, a dose total administrada e o período de recuperação do propofol. Concluiu-se que a adição de butorfanol não produziu analgesia somática em gatos anestesiados com doses fracionadas de propofol.<br>Propofol is an intravenous anesthetic agent used for induction and maintenance of anesthesia but produces limited analgesia, and concomitant use of analgesics is necessary. The analgesic effect of butorphanol in somatic pain in cats anesthetized with intermittent doses of propofol was evaluated. Sixteen animals were randomly assigned to 2 groups. Control group animals were premedicated with IM acepromazine (0,2mg/kg) and after 15 minutes IV propofol (6mg/kg) was administered. Treatment group animals were premedicated with IM acepromazine (0,2mg/kg) and butorphanol (0,8mg/kg), mixed in the same syringe and after 15 minutes IV propofol (6mg/kg) was administered. In both groups anesthesia was maintained with repeated injections of propofol (3mg/kg) as needed, during 60 minutes. The need to complement propofol doses was determined by reactions to a skin pinch with a Kocher hemostatic forceps.Heart rate, respiratory rate, mean blood pressure, rectal body temperature and oxyhemoglobin saturation were also recorded. Administration of butorphanol caused minimal changes in cardiopulmonary variables compared to control group and did not affect duration of anesthesia and total dose of propofol or recovery period. We concluded that addition of butorphanol did not produce somatic analgesia during anesthesia maintained with repeated injections of propofol in cats

The first year of the BABAR experiment at PEP-II

The BABAR detector, situated at the SLAC PEP-II asymmetric e^+e^- collider, has been recording data at energies on and around the Upsilon(4S) resonance since May 1999. In this paper, we briefly describe the PEP-II B Factory and the BABAR detector. The performance presently achieved by the experiment in the areas of tracking, vertexing, calorimetry and particle identification is reviewed. Analysis concepts that are used in the various papers submitted to this conference are also discussed

Measurement of the time dependence of B0−Bˉ0B^{0}-\bar B^{0} oscillations using inclusive dilepton events

A preliminary study of time dependence of B^0-anti-B^0 oscillations using dilepton events is presented. The flavor of the B meson is determined by the charge sign of the lepton. To separate signal leptons from cascade and fake leptons we have used a method which combines several discriminating variables in a neural network. The time evolution of the oscillations is studied by reconstructing the time difference between the decays of the B mesons produced by the Y(4S) decay. With an integrated luminosity of 7.7 fb-1 collected on resonance by BABAR at the PEP-II asymmetric B Factory, we measure the difference in mass of the neutral B eigenstates, Delta_mB0 to be (0.507+/-0.015+/-0.022) x 10^{12} hbar-s^{-1}