A Bayesian technique for improving the sensitivity of the atmospheric neutrino L/E analysis

This paper outlines a method for improving the precision of atmospheric neutrino oscillation measurements. One experimental signature for these oscillations is an observed deficit in the rate of $\nu_{\mu}$ charged-current interactions with an oscillatory dependence on $L_{\nu}/E_{\nu}$, where $L_{\nu}$ is the neutrino propagation distance, and $E_{\nu}$ is the neutrino energy. For contained-vertex atmospheric neutrino interactions, the $L_{\nu}/E_{\nu}$ resolution varies significantly from event to event. The precision of the oscillation measurement can be improved by incorporating information on $L_{\nu}/E_{\nu}$ resolution into the oscillation analysis. In the analysis presented here, a Bayesian technique is used to estimate the $L_{\nu}/E_{\nu}$ resolution of observed atmospheric neutrinos on an event-by-event basis. By separating the events into bins of $L_{\nu}/E_{\nu}$ resolution in the oscillation analysis, a significant improvement in oscillation sensitivity can be achieved.Comment: 12 pages, 7 figures, submitted to Nucl. Instrum. Methods A, accompanies arXiv:1208.2915 [hep-ex

Scenario of Accelerating Universe from the Phenomenological \Lambda- Models

Dark matter, the major component of the matter content of the Universe, played a significant role at early stages during structure formation. But at present the Universe is dark energy dominated as well as accelerating. Here, the presence of dark energy has been established by including a time-dependent $\Lambda$ term in the Einstein's field equations. This model is compatible with the idea of an accelerating Universe so far as the value of the deceleration parameter is concerned. Possibility of a change in sign of the deceleration parameter is also discussed. The impact of considering the speed of light as variable in the field equations has also been investigated by using a well known time-dependent $\Lambda$ model.Comment: Latex, 9 pages, Major change

A Hybrid Approach to Parallel Pattern Discovery in C++

Funding: EU Horizon 2020 project, TeamPlay, grant number 779882, and UK EPSRC Discovery, grant number EP/P020631/1.Parallel pattern libraries offer a strong combination of abstraction and performance. However, discovering places in sequential code where parallel patterns should be introduced is still highly non-trivial, often requiring expert manual analysis and profiling. We present a hybrid discovery technique to detect instances of parallel patterns in sequential code. This employs both static and dynamic trace-based analysis, together with hotspot detection. We evaluate our pattern discovery mechanism on a number of representative benchmarks. We evaluate the performance of the resulting parallelised benchmarks on a 24-core parallel machine.Postprin

Aspects of electrostatics in a weak gravitational field

Several features of electrostatics of point charged particles in a weak, homogeneous, gravitational field are discussed using the Rindler metric to model the gravitational field. Some previously known results are obtained by simpler and more transparent procedures and are interpreted in an intuitive manner. Specifically: (i) We show that the electrostatic potential of a charge at rest in the Rindler frame is expressible as A_0=(q/l) where l is the affine parameter distance along the null geodesic from the charge to the field point. (ii) We obtain the sum of the electrostatic forces exerted by one charge on another in the Rindler frame and discuss its interpretation. (iii) We show how a purely electrostatic term in the Rindler frame appears as a radiation term in the inertial frame. (In part, this arises because charges at rest in a weak gravitational field possess additional weight due to their electrostatic energy. This weight is proportional to the acceleration and falls inversely with distance -- which are the usual characteristics of a radiation field.) (iv) We also interpret the origin of the radiation reaction term by extending our approach to include a slowly varying acceleration. Many of these results might have possible extensions for the case of electrostatics in an arbitrary static geometry. [Abridged Abstract]Comment: 26 pages; accepted for publication in Gen.Rel.Gra

Predictors of cardiac events after major vascular surgery: Role of clinical characteristics, dobutamine echocardiography, and beta-blocker therapy

CONTEXT: Patients who undergo major vascular surgery are at increased risk of perioperative cardiac complications. High-risk patients can be identified by clinical factors and noninvasive cardiac testing, such as dobutamine stress echocardiography (DSE); however, such noninvasive imaging techniques carry significant disadvantages. A recent study found that perioperative beta-blocker therapy reduces complication rates in high-risk individuals. OBJECTIVE: To examine the relationship of clinical characteristics, DSE results, beta-blocker therapy, and cardiac events in patients undergoing major vascular surgery. DESIGN AND SETTING: Cohort study conducted in 1996-1999 in the following 8 centers: Erasmus Medical Centre and Sint Clara Ziekenhuis, Rotterdam, Twee Steden Ziekenhuis, Tilburg, Academisch Ziekenhuis Utrecht, Utrecht, and Medisch Centrum Alkmaar, Alkmaar, the Netherlands; Ziekenhuis Middelheim, Antwerp, Belgium; and San Gerardo Hospital, Monza, Istituto di Ricovero e Cura a Carattere Scientifico, San Giovanni Rotondo, Italy. PATIENTS: A total of 1351 consecutive patients scheduled for major vascular surgery; DSE was performed in 1097 patients (81%), and 360 (27%) received beta-blocker therapy. MAIN OUTCOME MEASURE: Cardiac death or nonfatal myocardial infarction within 30 days after surgery, compared by clinical characteristics, DSE results, and beta-blocker use. RESULTS: Forty-five patients (3.3%) had perioperative cardiac death or nonfatal myocardial infarction. In multivariable analysis, important clinical determinants of adverse outcome were age 70 years or older; current or prior angina pectoris; and prior myocardial infarction, heart failure, or cerebrovascular accident. Eighty-three percent of patients had less than 3 clinical risk factors. Among this subgroup, patients receiving beta-blockers had a lower risk of cardiac complications (0.8% [2/263]) than those not receiving beta-blockers (2.3% [20/855]), and DSE had minimal additional prognostic value. In patients with 3 or more risk factors (17%), DSE provided additional prognostic information, for patients without stress-induced ischemia had much lower risk of events than those with stress-induced ischemia (among those receiving beta-blockers, 2.0% [1/50] vs 10.6% [5/47]). Moreover, patients with limited stress-induced ischemia (1-4 segments) experienced fewer cardiac events (2.8% [1/36]) than those with more extensive ischemia (>/=5 segments, 36% [4/11]). CONCLUSION: The additional predictive value of DSE is limited in clinically low-risk patients receiving beta-blockers. In clinical practice, DSE may be avoided in a large number of patients who can proceed safely for surgery without delay. In clinically intermediate- and high-risk patients receiving beta-blockers, DSE may help identify those in whom surgery can still be performed and those in whom cardiac revascularization should be considered

Optimisation of assessment of maximal rate of heart rate increase for tracking training-induced changes in endurance exercise performance

The maximal rate of heart rate (HR) increase (rHRI), a marker of HR acceleration during transition from rest to submaximal exercise, correlates with exercise performance. In this cohort study, whether rHRI tracked performance better when evaluated over shorter time-periods which include a greater proportion of HR acceleration and less steady-state HR was evaluated. rHRI and five-km treadmill running time-trial performance (5TTT) were assessed in 15 runners following one week of light training (LT), two weeks of heavy training (HT) and 10-day taper (T). rHRI was the first derivative maximum of a sigmoidal curve fit to one, two, three and four minutes of R-R data during transition from rest to running at 8 km/h (rHRI8 km/h), 10.5 km/h, 13 km/h and transition from 8 to 13 km/h (rHRI8-13km/h). 5TTT time increased from LT to HT (effect size [ES] 1.0, p < 0.001) then decreased from HT to T (ES -1.7, p < 0.001). 5TTT time was inversely related to rHRI8 km/h assessed over two (B = -5.54, p = 0.04) three (B = -5.34, p = 0.04) and four (B = -5.37, p = 0.04) minutes, and rHRI8-13km/h over one (B = -11.62, p = 0.006) and three (B = -11.44, p = 0.03) minutes. 5TTT correlated most consistently with rHRI8 km/h. rHRI8 km/h assessed over two to four minutes may be suitable for evaluating athlete responses to training.Maximillian J. Nelson, Clint R. Bellenger, Rebecca L. Thomson, Eileen Y. Robertson, Kade Davison, Daniela Schäfer Olstad, Jonathan D. Buckle

Dynamic scaling and quasi-ordered states in the two dimensional Swift-Hohenberg equation

The process of pattern formation in the two dimensional Swift-Hohenberg equation is examined through numerical and analytic methods. Dynamic scaling relationships are developed for the collective ordering of convective rolls in the limit of infinite aspect ratio. The stationary solutions are shown to be strongly influenced by the strength of noise. Stationary states for small and large noise strengths appear to be quasi-ordered and disordered respectively. The dynamics of ordering from an initially inhomogeneous state is very slow in the former case and fast in the latter. Both numerical and analytic calculations indicate that the slow dynamics can be characterized by a simple scaling relationship, with a characteristic dynamic exponent of $1/4$ in the intermediate time regime

Role of surface roughness in hard x-ray emission from femtosecond laser produced copper plasmas

The hard x-ray emission in the energy range of 30-300 keV from copper plasmas produced by 100 fs, 806 nm laser pulses at intensities in the range of 10$^{15}-10^{16}$ W cm$^{-2}$ is investigated. We demonstrate that surface roughness of the targets overrides the role of polarization state in the coupling of light to the plasma. We further show that surface roughness has a significant role in enhancing the x-ray emission in the above mentioned energy range.Comment: 5 pages, 4 figures, to appear in Phys. Rev.