Stochastic Pulse Switching in a Degenerate Resonant Optical Medium

Using the idealized integrable Maxwell-Bloch model, we describe random optical-pulse polarization switching along an active optical medium in the Lambda-configuration with disordered occupation numbers of its lower energy sub-level pair. The description combines complete integrability and stochastic dynamics. For the single-soliton pulse, we derive the statistics of the electric-field polarization ellipse at a given point along the medium in closed form. If the average initial population difference of the two lower sub-levels vanishes, we show that the pulse polarization will switch intermittently between the two circular polarizations as it travels along the medium. If this difference does not vanish, the pulse will eventually forever remain in the circular polarization determined by which sub-level is more occupied on average. We also derive the exact expressions for the statistics of the polarization-switching dynamics, such as the probability distribution of the distance between two consecutive switches and the percentage of the distance along the medium the pulse spends in the elliptical polarization of a given orientation in the case of vanishing average initial population difference. We find that the latter distribution is given in terms of the well-known arcsine law

Allotransplantation of cultured parathyroid cells from a living unrelated donor to a kidney transplant recipient: the first clinical observation

АЛЛОТРАНСПЛАНТАЦИЯПОЧЕК ТРАНСПЛАНТАЦИЯГИПОПАРАТИРЕОЗПОСЛЕОПЕРАЦИОННЫЕ ОСЛОЖНЕНИЯПАРАТИРОЦИТЫИММУНОСУПРЕССИЯЦель. Продемонстрировать возможность успешного лечения послеоперационного гипопаратиреоза тяжелой степени тяжести путем аллотрансплантации культивированных паратироцитов реципиенту с по- чечным трансплантатом. Материал и методы. Реципиентом паратиреоидного аллотрансплантата была 37-летняя женщина с почечным трансплантатом и гипопаратиреозом тяжелой степени тяжести на фоне интенсивной заместительной терапии. Симптомы тетании, высокая судорожная готовность (симптомы Труссо, Хвостека), крайне низкие показатели общего/ионизированного кальция (1,71/0,98 ммоль/л) и паратгормона (1,7 пг/ мл) в периферической крови явились показанием к паратиреоидной аллотрансплантации. В толщу левой плечелучевой мышцы реципиента имплантировали 21?106 культивированных паратироцитов, полученных от живого неродственного донора (62-летней женщины) с вторичным гиперпаратиреозом. Выбор места для паратиреоидной аллотрансплантации обусловило отсутствие артериовенозной фистулы на стороне пере- садки. Иммуносупрессивная терапия включала прием 150 мг/сутки циклоспорина, 720 мг/сутки микофе- ноловой кислоты, 6 мг/сутки метилпреднизолона. Результаты. В послеоперационном периоде осложнений вмешательства, местных и общих побоч- ных эффектов на паратиреоидный клеточный аллотрансплантат отмечено не было. Через 1 месяц после пересадки паратироцитов наступила клинико-лабораторная компенсация гипопаратиреоза: концентрация паратгормона возросла до 14,7 пг/мл и достигла максимального значения (61,7 пг/мл) через 3,5 месяца. На протяжении 6-месячного периода наблюдения судорожный синдром не возникал, симптомы Труссо и Хвостека купировались, объем пероральной заместительной терапии существенно уменьшился, исчезла потребность в парентеральном введении солевых растворов кальция. Через 6 месяцев после пересадки па- циентка ведет привычный образ жизни и принимает per os 0,5 г кальция в сутки. Заключение. Комбинированная аллотрансплантация трупной почки и культивированных паратиро- цитов, выделенных из гиперплазированной паратиреоидной ткани живого неродственного донора, являет- ся эффективным методом лечения перманентного гипопаратиреоза тяжелой степени тяжести у пациентов, нуждающихся в органной трансплантации с последующей иммуносупрессивной терапией.Objectives. To demonstrate the possibility of successful treatment of a severe postsurgical hypoparathyroidism by the cultured parathyrocyte allotransplantation to a kidney transplant recipient. Methods. A 37-year-old female with the kidney transplant and a severe postsurgical hypoparathyroidism on the background of intensive replacement therapy was a recipient of parathyroid allograft. The indications for parathyroid autotransplantation include symptoms of tetany, high convulsive readiness (Chvostek’s and Trousseau’s signs), extremely low rates of total/ionized calcium (1,71/0,98 mmol/L) and parathyroid hormone (1,7 pg/ml) in the peripheral blood. Culture (21?106) of parathyroid cells obtained from a living unrelated donor (62-year-old female) with the secondary hyperparathyroidism was implanted into the recipients’ left brachioradialis muscle. Site selection for parathyroid allograft was conditioned by the absence of arteriovenous fistula on the side of the transplantation. Immunosuppressive therapy consisted of 150 mg/day of cyclosporine, 720 mg/day of mycophenolic acid, 6 mg/day of methylprednisolone. Results. No postoperative complications of the intervention, local and general side effects on the parathyroid cell allograft were observed. Clinical and laboratory improvement of hypoparathyroidism occurred 1 month after the transplantation: parathyroid hormone concentration increased up to 14,7 pg/ml and reached a maximum value (61,7 pg/mL) after 3,5 months. No convulsions were observed over a 6-month follow-up, Chvostek’s and Trousseau’s signs were stopped, the amount of oral substitution therapy significantly reduced, and there was no more need for parenteral administration of calcium salt solutions. Six months after transplantation a patient led a very active life and took per os 0,5 g/day of calcium. Conclusion. Combined allotransplantation of cadaveric kidneys and cultured parathyroid cells obtained from the hyperplastic parathyroid tissue of a living unrelated donor is considered to be an effective treatment of permanent severe hypoparathyroidism in patients who need the organ transplantation with subsequent immunosuppressive therapy

Search for the Higgs boson in events with missing transverse energy and b quark jets produced in proton-antiproton collisions at s**(1/2)=1.96 TeV

We search for the standard model Higgs boson produced in association with an electroweak vector boson in events with no identified charged leptons, large imbalance in transverse momentum, and two jets where at least one contains a secondary vertex consistent with the decay of b hadrons. We use ~1 fb-1 integrated luminosity of proton-antiproton collisions at s**(1/2)=1.96 TeV recorded by the CDF II experiment at the Tevatron. We find 268 (16) single (double) b-tagged candidate events, where 248 +/- 43 (14.4 +/- 2.7) are expected from standard model background processes. We place 95% confidence level upper limits on the Higgs boson production cross section for several Higgs boson masses ranging from 110 GeV/c2 to 140 GeV/c2. For a mass of 115 GeV/c2 the observed (expected) limit is 20.4 (14.2) times the standard model prediction.Comment: 8 pages, 2 figures, submitted to Phys. Rev. Let

Evidence for the exclusive decay Bc+- to J/psi pi+- and measurement of the mass of the Bc meson

We report first evidence for a fully reconstructed decay mode of the B_c^{\pm} meson in the channel B_c^{\pm} \to J/psi \pi^{\pm}, with J/psi \to mu^+mu^-. The analysis is based on an integrated luminosity of 360 pb$^{-1} in p\bar{p} collisions at 1.96 TeV center of mass energy collected by the Collider Detector at Fermilab. We observe 14.6 \pm 4.6 signal events with a background of 7.1 \pm 0.9 events, and a fit to the J/psi pi^{\pm} mass spectrum yields a B_c^{\pm} mass of 6285.7 \pm 5.3(stat) \pm 1.2(syst) MeV/c^2. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%.Comment: 7 pages, 3 figures. Version 3, accepted by PR

Measurement of the Helicity Fractions of W Bosons from Top Quark Decays Using Fully Reconstructed top-antitop Events with CDF II

We present a measurement of the fractions F_0 and F_+ of longitudinally polarized and right-handed W bosons in top quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 318 pb -1. We select ttbar candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle theta*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W momentum in the top quark rest frame. The cos(theta*) distribution in the data is determined by full kinematic reconstruction of the ttbar candidates. We find F_0 = 0.85 +0.15 -0.22 (stat) +- 0.06 (syst) and F_+ = 0.05 +0.11 -0.05 (stat) +- 0.03 (syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W bosons of F_+ < 0.26 at the 95% confidence level.Comment: 11 pages, 2 figures, submitted to Phys. Rev.

Observation and Mass Measurement of the Baryon Ξb−\Xi^-_b

We report the observation and measurement of the mass of the bottom, strange baryon $\Xi^-_b$ through the decay chain $\Xi^-_b \to J/\psi \Xi^-$, where $J/\psi \to \mu^+ \mu^-$, $\Xi^- \to \Lambda \pi^-$, and $\Lambda \to p \pi^-$. Evidence for observation is based on a signal whose probability of arising from the estimated background is 6.6 x 10^{-15}, or 7.7 Gaussian standard deviations. The $\Xi^-_b$ mass is measured to be $5792.9\pm 2.5$ (stat.) $\pm 1.7$ (syst.) MeV/$c^2$.Comment: Minor text changes for the second version. Accepted by Phys. Rev. Let

Top quark mass measurement using the template method at CDF

We present a measurement of the top quark mass in the lepton+jets and dilepton channels of $t\bar{t}$ decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb$^{-1}$ of $p\bar{p}$ collisions at Tevatron with $\sqrt{s}=1.96$ TeV, collected with the CDF II detector. The measurement is performed by constructing templates of three kinematic variables in the lepton+jets and two kinematic variables in the dilepton channel. The variables are two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from the $W$ decay in the lepton+jets channel, and a reconstructed top quark mass and $m_{T2}$, a variable related to the transverse mass in events with two missing particles, in the dilepton channel. The simultaneous fit of the templates from signal and background events in the lepton+jets and dilepton channels to the data yields a measured top quark mass of $M_{top} = 172.1 \pm 1.1(stat) \pm 0.9(syst).$Comment: submitted to Phys. Rev.

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s) = 1.96 TeV

We present a measurement of the top quark pair production cross section in ppbar collisions at sqrt(s)=1.96 TeV using 318 pb^{-1} of data collected with the Collider Detector at Fermilab. We select ttbar decays into the final states e nu + jets and mu nu + jets, in which at least one b quark from the t-quark decays is identified using a secondary vertex-finding algorithm. Assuming a top quark mass of 178 GeV/c^2, we measure a cross section of 8.7 +-0.9 (stat) +1.1-0.9 (syst) pb. We also report the first observation of ttbar with significance greater than 5 sigma in the subsample in which both b quarks are identified, corresponding to a cross section of 10.1 +1.6-1.4(stat)+2.0-1.3 (syst) pb.Comment: Accepted for publication in Physics Review Letters, 7 page

Polarizations of J/psi and psi(2S) Mesons Produced in ppbar Collisions at 1.96 TeV

We have measured the polarizations of \jpsi and \psiprime mesons as functions of their transverse momentum \pt when they are produced promptly in the rapidity range $|y|<0.6$ with \pt \geq 5 \pgev. The analysis is performed using a data sample with an integrated luminosity of about 800 \ipb collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as \pt increases from 5 to 30 \pgev. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of \jpsi and \psiprime mesons from $B$-hadron decays are also reported.Comment: 8 pages, 7 figures, published in Physical Review Letter