740 research outputs found

    An Ultrastable and Dense Single-Molecule Click Platform for Sensing Protein–Deoxyribonucleic Acid Interactions

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    An ultrastable, highly dense single-molecule assay ideal for observing protein–DNA interactions is demonstrated. Stable click tethered particle motion leverages next generation click-chemistry to achieve an ultrahigh density of surface tethered reporter particles, and has low non-specific interactions, is stable at elevated temperatures to at least 45 °C, and is compatible with Mg2+, an important ionic component of many regulatory protein–DNA interactions. Prepared samples remain stable, with little degradation, for &gt;6 months in physiological buffers. These improvements enable the authors to study previously inaccessible sequence and temperature-dependent effects on DNA binding by the bacterial protein, histone-like nucleoid-structuring protein, a global transcriptional regulator found in Escherichia coli. This greatly improved assay can directly be translated to accelerate existing tethered particle-based, single-molecule biosensing applications.</p

    Adiabatic transfer of light in a double cavity and the optical Landau-Zener problem

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    We analyze the evolution of an electromagnetic field inside a double cavity when the difference in length between the two cavities is changed, e.g. by translating the common mirror. We find that this allows photons to be moved deterministically from one cavity to the other. We are able to obtain the conditions for adiabatic transfer by first mapping the Maxwell wave equation for the electric field onto a Schroedinger-like wave equation, and then using the Landau-Zener result for the transition probability at an avoided crossing. Our analysis reveals that this mapping only rigorously holds when the two cavities are weakly coupled (i.e. in the regime of a highly reflective common mirror), and that, generally speaking, care is required when attempting a hamiltonian description of cavity electrodynamics with time-dependent boundary conditions.Comment: 24 pages, 18 figures. Version 2 includes a new section (Sec. VIII) on the regimes of validity of the Schroedinger-like equations and also of the adiabatic approximation, together with a new figure (Fig. 10). The discussion section (Sec. XI) has also been enhance

    A protocol for thoracic radiation therapy in patients with cardiac implantable electronic devices

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    Prolonged lifespan and improved diagnostic and treatment modalities have led to significant progress in the diagnosis and treatment of cardiovascular disease and cancer. A substantial number of patients with malignancies also have cardiovascular disease at the time of cancer treatment. Per literature, over one million implantable cardiac devices are inserted annually. Ionizing radiation, especially in the thoracic area is related to cardiac implantable electronic device (CIED) damage and malfunction. Besides that, CIED can interfere with radiotherapy planning and delivery, as well as patient motivation to undergo radiotherapy treatment. Management of oncology patients, undergoing radiotherapy, for any indication, with a CIED is essential, and safe radiotherapy practice requires minimizing the risk to patients as much as possible, from pretherapy planning to posttherapy follow-up. A collaborative multidisciplinary approach, tailor-made for every single radiotherapy center is imperative to provide effective and safe radiotherapy for these patients. A collaboration of radiation oncologists, medical physicists and cardiologists from the University Clinical Center Kragujevac has created a local protocol for radiotherapy treatment and follow-up for patients receiving radiotherapy at the Center for Radiation Oncology University C linical Center Kragujevac, which provides safe and efficient delivery of an adequate radiotherapy dose to target volumes with appropriate cardiac monitoring.Publishe

    Adding abiraterone to androgen deprivation therapy in men with metastatic hormone-sensitive prostate cancer: a systematic review and meta-analysis

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    BACKGROUND: There is a need to synthesise the results of numerous randomised controlled trials evaluating the addition of therapies to androgen deprivation therapy (ADT) for men with metastatic hormone-sensitive prostate cancer (mHSPC). This systematic review aims to assess the effects of adding abiraterone acetate plus prednisone/prednisolone (AAP) to ADT. METHODS: Using our framework for adaptive meta-analysis (FAME), we started the review process before trials had been reported and worked collaboratively with trial investigators to anticipate when eligible trial results would emerge. Thus, we could determine the earliest opportunity for reliable meta-analysis and take account of unavailable trials in interpreting results. We searched multiple sources for trials comparing AAP plus ADT versus ADT in men with mHSPC. We obtained results for the primary outcome of overall survival (OS), secondary outcomes of clinical/radiological progression-free survival (PFS) and grade III-IV and grade V toxicity direct from trial teams. Hazard ratios (HRs) for the effects of AAP plus ADT on OS and PFS, Peto Odds Ratios (Peto ORs) for the effects on acute toxicity and interaction HRs for the effects on OS by patient subgroups were combined across trials using fixed-effect meta-analysis. FINDINGS: We identified three eligible trials, one of which was still recruiting (PEACE-1 (NCT01957436)). Results from the two remaining trials (LATITUDE (NCT01715285) and STAMPEDE (NCT00268476)), representing 82% of all men randomised to AAP plus ADT versus ADT (without docetaxel in either arm), showed a highly significant 38% reduction in the risk of death with AAP plus ADT (HR = 0.62, 95% confidence interval [CI] = 0.53-0.71, p = 0.55 × 10(-10)), that translates into a 14% absolute improvement in 3-year OS. Despite differences in PFS definitions across trials, we also observed a consistent and highly significant 55% reduction in the risk of clinical/radiological PFS (HR = 0.45, 95% CI = 0.40-0.51, p = 0.66 × 10(-36)) with the addition of AAP, that translates to a 28% absolute improvement at 3 years. There was no evidence of a difference in the OS benefit by Gleason sum score, performance status or nodal status, but the size of the benefit may vary by age. There were more grade III-IV acute cardiac, vascular and hepatic toxicities with AAP plus ADT but no excess of other toxicities or death. INTERPRETATION: Adding AAP to ADT is a clinically effective treatment option for men with mHSPC, offering an alternative to docetaxel for men who are starting treatment for the first time. Future research will need to address which of these two agents or whether their combination is most effective, and for whom

    Observation of the Baryonic Flavor-Changing Neutral Current Decay Lambda_b -> Lambda mu+ mu-

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    We report the first observation of the baryonic flavor-changing neutral current decay Lambda_b -> Lambda mu+ mu- with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses ppbar collisions data sample corresponding to 6.8fb-1 at sqrt{s}=1.96TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Lambda_b -> Lambda mu+ mu- are measured. We find B(Lambda_b -> Lambda mu+ mu-) = [1.73+-0.42(stat)+-0.55(syst)] x 10^{-6}. We also report the first measurement of the differential branching ratio of B_s -> phi mu+ mu- using 49 signal events. In addition, we report branching ratios for B+ -> K+ mu+ mu-, B0 -> K0 mu+ mu-, and B -> K*(892) mu+ mu- decays.Comment: 8 pages, 2 figures, 4 tables. Submitted to Phys. Rev. Let

    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

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    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

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

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    We report the observation and measurement of the mass of the bottom, strange baryon Ξb\Xi^-_b through the decay chain ΞbJ/ψΞ\Xi^-_b \to J/\psi \Xi^-, where J/ψμ+μJ/\psi \to \mu^+ \mu^-, ΞΛπ\Xi^- \to \Lambda \pi^-, and Λpπ\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 Ξb\Xi^-_b mass is measured to be 5792.9±2.55792.9\pm 2.5 (stat.) ±1.7\pm 1.7 (syst.) MeV/c2c^2.Comment: Minor text changes for the second version. Accepted by Phys. Rev. Let

    Precise measurement of the top quark mass in the lepton+jets topology at CDF II

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    We present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. We analyze events from the single lepton plus jets final state (ttˉW+bWbˉlνbqqˉbˉt\bar t\to W^+bW^-\bar b\to l\nu b q \bar q'\bar b). The top quark mass is extracted using a direct calculation of the probability density that each event corresponds to the ttˉt\bar t final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained {\it in situ} by the hadronic WW boson mass. Using 167 events observed in 955 pb1^{{-}1} of integrated luminosity, we achieve the single most precise measurement of the top quark mass, 170.8 ±\pm 2.2 (stat.) ±\pm 1.4 (syst.) GeV/c2c^2.Comment: accepted by Phys. Rev. Let

    Search for Pair Production of Scalar Top Quarks Decaying to a tau Lepton and a b Quark in ppbar Collisions at sqrt{s}=1.96 TeV

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    We search for pair production of supersymmetric top quarks (~t_1), followed by R-parity violating decay ~t_1 -> tau b with a branching ratio beta, using 322 pb^-1 of ppbar collisions at sqrt{s}=1.96 TeV collected by the CDF II detector at Fermilab. Two candidate events pass our final selection criteria, consistent with the standard model expectation. We set upper limits on the cross section sigma(~t_1 ~tbar_1)*beta^2 as a function of the stop mass m(~t_1). Assuming beta=1, we set a 95% confidence level limit m(~t_1)>153 GeV/c^2. The limits are also applicable to the case of a third generation scalar leptoquark (LQ_3) decaying LQ_3 -> tau b.Comment: 7 pages, 2 eps figure

    Top quark mass measurement using the template method at CDF

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    We present a measurement of the top quark mass in the lepton+jets and dilepton channels of ttˉt\bar{t} decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb1^{-1} of ppˉp\bar{p} collisions at Tevatron with s=1.96\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 WW decay in the lepton+jets channel, and a reconstructed top quark mass and mT2m_{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 Mtop=172.1±1.1(stat)±0.9(syst).M_{top} = 172.1 \pm 1.1(stat) \pm 0.9(syst).Comment: submitted to Phys. Rev.
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