Measurements of single top quark cross sections at 13 TeV with the CMS experiment

An overview of recent measurements of inclusive and differential single top quark cross sections at 13 TeV with the CMS experiment is given in this note. This includes measurements targeting the $t$-channel and tW production modes resulting in inclusive cross sections of \sigma_{t\mathrm{\mbox{-}ch.}}=238\pm32~\mathrm{pb} and $\sigma_\mathrm{tW}=63.1\pm6.6~\mathrm{pb}$ respectively. In addition, the $t$-channel cross section has been measured differentially as a function of the top quark transverse momentum and rapidity. The results are found in agreement with the standard model expectations. Furthermore, a search for single top quark production in association with a Z boson is detailed which yields an observed (expected) significance of 3.7 (3.1) standard deviations.Comment: 5 pages, 4 figures, proceedings 10th International Workshop on Top Quark Physics, Braga, Portugal, September 17-22, 201

Measurement of Top-Quark Polarization in t-channel Single-Top Production

The measurement of the top quark polarization, sensitive to the electroweak coupling structure, in t-channel single-top production is presented. Events are analyzed corresponding to an integrated luminosity of approximately $20~\mathrm{fb^{-1}}$ recorded with the CMS detector during pp collisions at $\sqrt{s}=8~\mathrm{TeV}$. By requiring one isolated lepton (muon or electron), two jets, and missing transverse energy, an angular asymmetry, sensitive to the polarization of the top quark, is reconstructed in the top-quark rest frame. The corresponding angular asymmetry at parton level is inferred from data in a phase space with enhanced single-top t-channel candidates through unfolding. Remaining background contributions are estimated through a ML-fit and subtracted. A polarization of $P_{t}=0.82\pm0.12\mathrm{~(stat.)}\pm0.32\mathrm{~(syst.)}$ is measured assuming a spin-analyzing power of the charged lepton stemming from the top decay of $100\%$.Comment: Presented at 7th International Workshop on Top Quark Physics 2014, 4 pages, 3 figure

Sub-Surface Meridional flow, Vorticity and the life time of Solar Active Regions

Solar sub-surface fluid topology provides an indirect approach to examine the internal characteristics of active regions (ARs). Earlier studies have revealed the prevalence of strong flows in the interior of ARs having complex magnetic fields. Using the Doppler data obtained by the Global Oscillation Network Group (GONG) project for a sample of 74 ARs, we have discovered the presence of steep gradients in meridional velocity at depths ranging from 1.5 to 5 Mm in flare productive ARs. The sample of these ARs is taken from the Carrington rotations 1980--2052 covering the period August 2001-January 2007. The gradients showed an interesting hemispheric trend of negative (positive) signs in the northern (southern) hemisphere, i.e., directed toward the equator. We have discovered three sheared layers in the depth range of 0 - 10 Mm, providing an evidence of complex flow structures in several ARs. An important inference derived from our analysis is that the location of the deepest zero vertical vorticity is correlated with the remaining life time of ARs. This new finding may be employed as a tool for predicting the life expectancy of an AR.Comment: 20 pages, 4 figures, To be appear in the Astrophysical Journal Letter

Variations in pp-Mode Parameters with Changing Onset-Time of a Large Flare

It is expected that energetic solar flares releasing large amount of energy at the photosphere may be able to excite the acoustic ($p$-) modes of oscillations. We have determined the characteristic properties of mode parameters by applying the ring diagram technique to 3-D power spectra obtained for solar active region NOAA 10486 during the long duration energetic X17.2/4B flare of October 28, 2003. Strong evidence of substantial increase in mode amplitude and systematic variations in sub-surface flows, i.e., meridional and zonal components of velocity, kinetic helicity, vorticity, is found from comparison of the pre- to the post-flare phases.Comment: 14 pages, 4 figure

Randomized Online Algorithms with High Probability Guarantees

We study the relationship between the competitive ratio and the tail distribution of randomized online problems. To this end, we define a broad class of online problems that includes some of the well-studied problems like paging, k-server and metrical task systems on finite metrics, and show that for these problems it is possible to obtain, given an algorithm with constant expected competitive ratio, another algorithm that achieves the same solution quality up to an arbitrarily small constant error with high probability; the "high probability" statement is in terms of the optimal cost. Furthermore, we show that our assumptions are tight in the sense that removing any of them allows for a counterexample to the theorem

Evidence-Based Protocol: Decreasing Falls and Falls with Injury in a NSDU

Patient falls in acute care tend to be the most common adverse events reported. The Centers for Medicare and Medicaid Services report that fall-related injuries are classified as hospital-acquired conditions and no longer reimburses for the diagnosis and treatment of injuries incurred from falls during hospitalization. Falls are decreasing at too slow a rate even with a variety of fall prevention guidelines being available. Falls are a complex problem within hospitals and the prevention of falls is challenging. Literature supports the individualization of fall prevention interventions based on the risk factors exhibited by a patient. Tailoring interventions to specific fall risk factors will most likely reduce falls compared to the implementation of general interventions. The Joint Commission Center for Transforming Healthcare Targeted Solutions Tool (TST) for falls will be implemented. The TST provides a systematic approach to decreasing falls and falls with injury by measuring the current state, analyzing and discovering causes for falls, and the implementation of targeted solutions. The TST utilizes define, measure, analyze, improve, and control methodology to guide an organization step by step in fall prevention. This approach helps an organization identify factors contributing to falls and then provides targeted solutions to prevent falls for hospitalized adult patients. The nature of this project is to determine if the use of fall prevention interventions that target patient-specific fall risk factors will reduce the number of patient falls and falls with injury in the microsystem of a Neuro Stepdown Unit compared to the universal fall risk prevention practice

Randomized online computation with high probability guarantees

We study the relationship between the competitive ratio and the tail distribution of randomized online minimization problems. To this end, we define a broad class of online problems that includes some of the well-studied problems like paging, k-server and metrical task systems on finite metrics, and show that for these problems it is possible to obtain, given an algorithm with constant expected competitive ratio, another algorithm that achieves the same solution quality up to an arbitrarily small constant error a with high probability; the "high probability" statement is in terms of the optimal cost. Furthermore, we show that our assumptions are tight in the sense that removing any of them allows for a counterexample to the theorem. In addition, there are examples of other problems not covered by our definition, where similar high probability results can be obtained.Comment: 20 pages, 2 figure

Advice Complexity of the Online Induced Subgraph Problem

Several well-studied graph problems aim to select a largest (or smallest) induced subgraph with a given property of the input graph. Examples of such problems include maximum independent set, maximum planar graph, and many others. We consider these problems, where the vertices are presented online. With each vertex, the online algorithm must decide whether to include it into the constructed subgraph, based only on the subgraph induced by the vertices presented so far. We study the properties that are common to all these problems by investigating the generalized problem: for a hereditary property \pty, find some maximal induced subgraph having \pty. We study this problem from the point of view of advice complexity. Using a result from Boyar et al. [STACS 2015], we give a tight trade-off relationship stating that for inputs of length n roughly n/c bits of advice are both needed and sufficient to obtain a solution with competitive ratio c, regardless of the choice of \pty, for any c (possibly a function of n). Surprisingly, a similar result cannot be obtained for the symmetric problem: for a given cohereditary property \pty, find a minimum subgraph having \pty. We show that the advice complexity of this problem varies significantly with the choice of \pty. We also consider preemptive online model, where the decision of the algorithm is not completely irreversible. In particular, the algorithm may discard some vertices previously assigned to the constructed set, but discarded vertices cannot be reinserted into the set again. We show that, for the maximum induced subgraph problem, preemption cannot help much, giving a lower bound of $\Omega(n/(c^2\log c))$ bits of advice needed to obtain competitive ratio $c$, where $c$ is any increasing function bounded by \sqrt{n/log n}. We also give a linear lower bound for c close to 1