CMS Software Distribution on the LCG and OSG Grids

The efficient exploitation of worldwide distributed storage and computing resources available in the grids require a robust, transparent and fast deployment of experiment specific software. The approach followed by the CMS experiment at CERN in order to enable Monte-Carlo simulations, data analysis and software development in an international collaboration is presented. The current status and future improvement plans are described.Comment: 4 pages, 1 figure, latex with hyperref

Integration of highly crystalline C8-BTBT thin-films into simple logic gates and circuits

Highly crystalline organic thin films possess the charge carrier mobilities needed for high-performance, low-cost flexible electronics. However, only few reports exist that show the integration of these films into short-channel organic circuits. This work describes the integration of highly crystalline layers of the thermally and chemically fragile small molecule C8-BTBT. Thin films of this material are processed by a combination of zone-casting and homoepitaxial vacuum evaporation and display an average charge carrier mobility of 7.5 cm2/V in long channel transistors. The integration of these films into a circuit technology based on a 5 μm channel-length bottom-gate bottom-contact transistor topology results in inverters with gains up to 40 as well as a robust 19-stage ring oscillator. This circuit requires the simultaneous operation of 80 TFTs and displays a stage delay of 40 μs, resulting in an operating frequency of 630 Hz at an operating voltage of 10 V. With the help of circuit modelling, we quantify the relationship between the speed of ring oscillators and the contact resistance of individual transistors. Indeed, the successful integration of highly-crystalline layers with high intrinsic mobility stresses the need for advances in contact engineering

Internal Medicine Residents Reject “Longer and Gentler” Training

BACKGROUND: Increasing complexity of medical care, coupled with limits on resident work hours, has prompted consideration of extending Internal Medicine training. It is unclear whether further hour reductions and extension of training beyond the current duration of 3 years would be accepted by trainees. OBJECTIVE: We aimed to determine if further work-hour reductions and extension of training would be accepted by trainees and whether resident burnout affects their opinions. DESIGN: A postal survey was sent to all 143 Internal Medicine residents at the University of Colorado School of Medicine in May 2004. MEASUREMENTS: The survey contained questions related to opinions on work-hour limits using a 5-point Likert scale ranging from strongly agree to strongly disagree. Burnout was measured using the Maslach Burnout Inventory, organized into three subscales: emotional exhaustion (EE), depersonalization (DP), and personal accomplishment, with burnout defined as high EE or DP. RESULTS: Seventy-four percent (106/143) of residents returned the survey. The vast majority (84%) of residents disagreed or strongly disagreed with extending training to 4 or 5 years. Burnout residents were less averse to extending training (strongly agree or agree, 18.9% vs 4.3%, P = .04). The majority of residents (68.9%) disagreed or strongly disagreed with establishing a 60-hour/week limit. Residents who met the criteria for burnout were more likely to agree that a 60-hour limit would be better than an 80-hour limit (strongly agree or agree, 22% vs 8%, P = .02). CONCLUSIONS: In this program, most Internal Medicine residents are strongly opposed to extending their training to 4 or 5 years and would prefer the current 80 hours/week cap. A longer, less intense pace of Internal Medicine training seems to be less attractive in the eyes of current trainees

Metasurface optics with on-axis polarization control for terahertz sensing applications

Non-destructive testing and imaging of materials with unknown properties are important applications of terahertz technology. Different contrast forming methods are available to obtain diverse information on the imaged region, including intensity, color, phase and polarization. Polarimetric imaging is relatively under-investigated owing to the difficulty in its implementation with complex optical arrangements. In this paper we present the design and monolithic fabrication of an anisotropic metasurface that incorporates several beam forming functions in a single layer with high efficiency thus simplifying instrument construction. The probe beam generated by the metasurface consists of an orthogonally polarized pair of collinear Bessel beams that create a well-defined on-axis change of polarization. The metasurface is integrated into a polarimetric imaging microscope for 3D beam profiling and sensing experiments at 2.52 THz. An analytical model to describe the on-axis polarization variation was found to be in excellent agreement with both finite-difference time-domain (FDTD) simulations and the experimental results. The setup was used to measure the refractive index and diattenuation of homogeneous sample regions in a proof-of-principle application. We anticipate this technology will find future application in non-destructive testing and polarimetric imaging of polymer composites and 3D profilometry of reflective surfaces

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO

Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO