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Methodology to reduce cancellations of scheduled

Vaz, Clara B.
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Conferência ou Objeto de Conferência
Português
Relevância na Pesquisa
17.259888%
Purpose - This study presents an integrated methodology to support the logistics management in health facilities in waste reduction and elimination, by providing simple and low cost solutions to minimize the cancellation of scheduled surgeries. The methodology is applied in a Portuguese public hospital. This approach promotes and improves the quality of services to patients. Design/methodology/approach - The methodology is a problem-solving process which could be applied to manage the flows of services (and materials), and associated information, from the point of origin to the point of care. This approach integrates several stages such as definition, measurement, analysis, improvement and control (DMAIC), and uses the quality and management tools required to obtain efficient and effective solutions to patients. Findings - The enhanced methodology contributes to an understanding the origins of the difficulties and waste. For the case study, the cancellation rate ranges from 19% and 21% in 2011 and 2012, respectively, and increases to 29% in 2013, although, this year the operating room performed the highest number of operations. The most critical root causes of cancellations are related to the changing patient’s state of health...

Amplitude Cancellation of Motor-Unit Action Potentials in the Surface Electromyogram Can Be Estimated With Spike-Triggered Averaging

Farina, Dario; Cescon, Corrado; Negro, Francesco; Enoka, Roger M.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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The study presents analytical, simulation, and experimental analyses of amplitude cancellation of motor-unit action potentials (APs) in the interference electromyogram (EMG) and its relation to the size of the spike-triggered average (STA) EMG. The amount of cancellation of motor-unit APs decreases monotonically as a function of the ratio between the root mean square (RMS) of the motor-unit AP and the RMS of the interference EMG signal. The theoretical derivation of this association indicates a method to measure cancellation in individual motor units by STA of the interference and squared EMGs. The theoretical relation was examined in both simulated EMG signals generated by populations of 200 motor units and experimental recordings of 492 and 184 motor-unit APs in the vastus medialis and abductor digiti minimi muscles, respectively. Although the theoretical relation predicted (R2 = 0.95; P < 0.001) the amount of cancellation in the simulated EMGs, the presence of motor-unit synchronization decreased the strength of the association for small APs. The decrease in size of the STA obtained from the squared EMG relative to that extracted from the interference EMG was predicted by the experimental measure of cancellation (R2 = 0.65; P < 0.001...

Respiratory manganese particle size, time-course and neurobehavioral outcomes in workers at a manganese alloy production plant

Park, Robert M.; Bouchard, Maryse F.; Baldwin, Mary; Bowler, Rosemarie; Mergler, Donna
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
17.543071%
The progression of manganism with chronic exposure to airborne manganese (Mn) is not well understood. Here, we further investigate the findings on exposure and neurobehavioral outcomes of workers from a silico- and ferromanganese production plant and non-exposed workers from the same community in 1990 and 2004, using a variety of exposure metrics that distinguish particle size and origin within the range of respirable airborne exposures. Mn exposure matrices for large respirable particulate (Mn-LRP, dust) and small respirable particulate (Mn-SRP, fume), based on process origins, were used together with detailed work histories since 1973 (plant opening), to construct exposure metrics including burdens and cumulative burdens with various clearance half-lives. For three out of eight 1990 neurobehavioral tests analyzed with linear regression models, duration of Mn exposure was the best predictor: Luria-Nebraska Neuropsychological Battery – Motor Scale, Trail-Making B and Finger Tapping. The Luria-Nebraska Motor Scale had the strongest association (t ~ 5.0, p < 10−6). For outcomes on three other tests, the duration and Mn-SRP metrics were comparable: Trail Making Test A, Cancellation H and Stroop Color-Word Test (color/word subtest). Delayed Word Recall was best predicted by Mn-SRP (based on square root or truncated air-concentrations). The Word score on the Stroop Color-Word Test was the only outcome for which Mn-LRP was the leading predictor (t = −2.92...

Essays on Asset Pricing and Econometrics

Jin, Tao
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
Português
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This dissertation presents three essays on asset pricing and econometrics. The first chapter identifies rare events and long-run risks simultaneously from a rich data set (the Barro-Ursua macroeconomic data set) and evaluates their contributions to asset pricing in a unified framework. The proposed model of rare events and long-run risks is estimated using a Bayesian Markov-chain Monte-Carlo method, and the estimates for the disaster process are closer to the data than those in the previous studies. Major evaluation results in asset pricing include: (1) for the unleveraged annual equity premium, the predicted values are 4.8%, 4.2%, and 1.0%, respectively; (2) for the Sharpe ratio, the values are 0.72, 0.66, and 0.15, respectively.; Economics

Flow and noise associated with the interaction of a square cylinder with a downstream flat plate.

Mat Ali, Mohamed Sukri
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011 Português
Relevância na Pesquisa
27.474849%
Bluff bodies are commonly found in many engineering applications, such as aircraft landing gear, pantograph systems of high speed trains and the rear view mirrors of passengers cars. In the event of bluff body interaction with flow, various flow induced phenomena may occur, such as vibration, unsteady aerodynamic loading, high pressure drag and flow induced noise. These phenomena can be altered by locating a secondary body in the wake of, and close to the bluff body. This alteration is due to the modification of the bluff body wake structure by the secondary body. The main objective of this study is to investigate the possibility of using a downstream flat plate for passive bluff body wake control. The success of this mechanism is evaluated by considering the reduction in unsteady aerodynamic loading together with the reduction in sound pressure level at an observer location. The observed new flow structures are explained using the results from a wide range of wake analyses to obtain a clear understanding of the physical phenomena of the wake-plate interaction. The test case under investigation consists of a square cylinder as the primary bluff body and a flat plate as the secondary body. The plate length and its position downstream of the square cylinder are varied systematically. This allows the optimal configuration of the plate for the least aerodynamic loading and radiated sound to be determined. The flow is simulated using two-dimensional Direct Numerical Simulation (DNS) at a Reynolds number of 150...

On the Modified Selberg Integral

Coppola, Giovanni
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/06/2010 Português
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We give a kind of \lq \lq approximate majorant principle\rq \rq \thinspace result for the \lq \lq modified Selberg integral\rq \rq, say $\modSel_f(N,h)$, of essentially bounded $f:\N \rightarrow \R$ (i.e., bounded by arbitrary small powers); i.e., we get an upper bound, in terms of the modified Selberg integral of a related function $F$ (with $|f\ast \mu|\ll F\ast \mu$, in the supports intersection), getting a \lq \lq square-root cancellation\rq \rq \thinspace for the error-terms. Here $\modSel_f(N,h)$ is the mean-square (in $N

On the Symmetry Integral

Coppola, Giovanni
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/07/2010 Português
Relevância na Pesquisa
26.849507%
We give a level one result for the "symmetry integral", say $I_f(N,h)$, of essentially bounded $f:\N \to \R$; i.e., we get a kind of "square-root cancellation" \thinspace bound for the mean-square (in $N0$ we have $g(n)\ll_{\epsilon} n^{\epsilon}$, and supported in $[1,Q]$, with $Q\ll N$ (so, the exponent of $Q$ relative to $N$, say the level $\lambda:=(\log Q)/(\log N)$ is $\lambda < 1$), where the symmetry sum weights the $f-$values in (almost all, i.e. all but $o(N)$ possible exceptions) the short intervals $[x-h,x+h]$ (with positive/negative sign at the right/left of $x$), with mild restrictions on $h$ (say, $h\to \infty$ and $h=o(\sqrt N)$, as $N\to \infty$).; Comment: Plain TeX(5 pages)

Generations of correlation averages

Coppola, Giovanni; Laporta, Maurizio
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.849507%
The present paper is a dissertation on the possible consequences of a conjectural bound for the so-called \thinspace modified Selberg integral of the divisor function $d_3$, i.e. a discrete version of the classical Selberg integral, where $d_3(n)=\sum_{abc=n}1$ is attached to the Cesaro weight $1-|n-x|/H$ in the short interval $|n-x|\le H$. Mainly, an immediate consequence is a non-trivial bound for the Selberg integral of $d_3$, improving recent results of Ivi\'c based on the standard approach through the moments of the Riemann zeta function on the critical line. We proceed instead with elementary arguments, by first applying the "elementary Dispersion Method" in order to establish a link between "weighted Selberg integrals" \thinspace of any arithmetic function $f$ and averages of correlations of $f$ in short intervals. Moreover, we provide a conditional generalization of our results to the analogous problem on the divisor function $d_k$ for any $k\ge 3$. Further, some remarkable consequences on the $2k-$th moments of the Riemann zeta function are discussed. Finally, we also discuss the essential properties that a general function $f$ should satisfy so that the estimation of its Selberg integrals could be approachable by our method.; Comment: The results are now conditional under square-root cancellation for the modified Selberg integral

On the modified Selberg integral of the three-divisor function $d_3$

Coppola, Giovanni
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.849507%
We prove a non-trivial result for the,say,modified Selberg integral $\modSel_3(N,h)$, of the divisor function $d_3(n):= \sum_{a}\sum_{b}\sum_{c, abc=n}1$; this integral is a slight modification of the corresponding Selberg integral, that gives the expected value of the function in short intervals. We get, in fact, $\modSel_3(N,h)\ll Nh^2L^2$, where $L:=\log N$; furthermore, as a byproduct, we obtain indications on the way in which it may be proved the weak sixth moment of the Riemann zeta function.(This was OLD abstract); Comment: The square-root cancellation for the modified Selberg integral of d3 is now a Conjecture. In fact,our proof of the Proposition is wrong;actually, the Proposition is too strong to be proven with present methods

Moments and oscillations of exponential sums related to cusp forms

Vesalainen, Esa V.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/02/2014 Português
Relevância na Pesquisa
26.849507%
We consider large values of long linear exponential sums involving Fourier coefficients of holomorphic cusp forms. The sums we consider involve rational linear twists $e(nh/k)$ with sufficiently small denominators. We prove both pointwise upper bounds and bounds for the frequency of large values. In particular, the $k$-aspect is treated. As an application we obtain upper bounds for all the moments of the sums in question. We also give the asymptotics with the right main term for fourth moments. We also consider the mean square of very short sums, proving that on average short linear sums with rational additive twists exhibit square root cancellation. This result is also proved in a slightly sharper form. Finally, the consideration of moment estimates for both long and short exponential sums culminates in a result concerning the oscillation of the long linear sums. Essentially, this result says that for positive proportion of time, such a sum stays in fairly long intervals, where its order of magnitude does not drop below the average order of magnitude and where its argument is in a given interval of length $3\pi/2$ and so can not wind around the origin.

On the Impact of Phase Noise on Active Cancellation in Wireless Full-Duplex

Sahai, Achaleshwar; Patel, Gaurav; Dick, Chris; Sabharwal, Ashutosh
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/12/2012 Português
Relevância na Pesquisa
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Recent experimental results have shown that full-duplex communication is possible for short-range communications. However, extending full-duplex to long-range communication remains a challenge, primarily due to residual self-interference even with a combination of passive suppression and active cancellation methods. In this paper, we investigate the root cause of performance bottlenecks in current full-duplex systems. We first classify all known full-duplex architectures based on how they compute their cancelling signal and where the cancelling signal is injected to cancel self-interference. Based on the classification, we analytically explain several published experimental results. The key bottleneck in current systems turns out to be the phase noise in the local oscillators in the transmit and receive chain of the full-duplex node. As a key by-product of our analysis, we propose signal models for wideband and MIMO full-duplex systems, capturing all the salient design parameters, and thus allowing future analytical development of advanced coding and signal design for full-duplex systems.; Comment: 35 pages, Submitted to IEEE Transactions on Vehicular Technology, Dec 2012

Performance Estimates of the Pseudo-Random Method for Radar Detection

Fish, Alexander; Gurevich, Shamgar
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/04/2014 Português
Relevância na Pesquisa
26.849507%
A performance of the pseudo-random method for the radar detection is analyzed. The radar sends a pseudo-random sequence of length $N$, and receives echo from $r$ targets. We assume the natural assumptions of uniformity on the channel and of the square root cancellation on the noise. Then for $r \leq N^{1-\delta}$, where $\delta > 0$, the following holds: (i) the probability of detection goes to one, and (ii) the expected number of false targets goes to zero, as $N$ goes to infinity.; Comment: 5 pages, two figures, to appear in Proceedings of ISIT 2014 - IEEE International Symposium on Information Theory, Honolulu

An Orthogonal Test of the $L$-functions Ratios Conjecture, II

Miller, Steven J.; Montague, David
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/11/2009 Português
Relevância na Pesquisa
27.13269%
Recently Conrey, Farmer, and Zirnbauer developed the L-functions Ratios conjecture, which gives a recipe that predicts a wealth of statistics, from moments to spacings between adjacent zeros and values of L-functions. The problem with this method is that several of its steps involve ignoring error terms of size comparable to the main term; amazingly, the errors seem to cancel and the resulting prediction is expected to be accurate up to square-root cancellation. We prove the accuracy of the Ratios Conjecture's prediction for the 1-level density of families of cuspidal newforms of constant sign (up to square-root agreement for support in (-1,1), and up to a power savings in (-2,2)), and discuss the arithmetic significance of the lower order terms. This is the most involved test of the Ratios Conjecture's predictions to date, as it is known that the error terms dropped in some of the steps do not cancel, but rather contribute a main term! Specifically, these are the non-diagonal terms in the Petersson formula, which lead to a Bessel-Kloosterman sum which contributes only when the support of the Fourier transform of the test function exceeds (-1, 1).; Comment: 36 pages, first draft

Surpassing the Ratios Conjecture in the 1-level density of Dirichlet $L$-functions

Fiorilli, Daniel; Miller, Steven J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.849507%
We study the $1$-level density of low-lying zeros of Dirichlet $L$-functions in the family of all characters modulo $q$, with $Q/2 < q\leq Q$. For test functions whose Fourier transform is supported in $(-3/2, 3/2)$, we calculate this quantity beyond the square-root cancellation expansion arising from the $L$-function Ratios Conjecture of Conrey, Farmer and Zirnbauer. We discover the existence of a new lower-order term which is not predicted by this powerful conjecture. This is the first family where the 1-level density is determined well enough to see a term which is not predicted by the Ratios Conjecture, and proves that the exponent of the error term $Q^{-\frac 12 +\epsilon}$ in the Ratios Conjecture is best possible. We also give more precise results when the support of the Fourier Transform of the test function is restricted to the interval $[-1,1]$. Finally we show how natural conjectures on the distribution of primes in arithmetic progressions allow one to extend the support. The most powerful conjecture is Montgomery's, which implies that the Ratios Conjecture's prediction holds for any finite support up to an error $Q^{-\frac 12 +\epsilon}$.; Comment: Version 1.2, 30 pages

About the influence of square-root Van Hove singularity on the critical temperature of high-Tc superconductors

Pashitskii, E. A.; Pentegov, V. I.; Abraham, E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 08/03/1998 Português
Relevância na Pesquisa
27.13269%
It is shown that the square-root Van Hove singularity in the density of states (DOS), associated with extended saddle-point features in the electronic spectra of cuprates, leads to a nonmonotonic dependence of Tc on the position of the Fermi level. As the result of cancellation of the DOS divergence in the electron-electron coupling constant, renormalized due to the account of strong-coupling effects, Tc approaches zero when Fermi level touches the bottom of the saddle. The Tc dependence on the doped holes' concentration, obtained in the strong coupling approximation, agrees with experimental data for the overdoped cuprate metal-oxides.; Comment: LaTeX 2.09, 4 pages, 3 Postscript figures, to be published in JETP Lett. v.67, No.7

Cancellation Meadows: a Generic Basis Theorem and Some Applications

Bergstra, Jan A.; Bethke, Inge; Ponse, Alban
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
27.696743%
Let Q_0 denote the rational numbers expanded to a "meadow", that is, after taking its zero-totalized form (0^{-1}=0) as the preferred interpretation. In this paper we consider "cancellation meadows", i.e., meadows without proper zero divisors, such as $Q_0$ and prove a generic completeness result. We apply this result to cancellation meadows expanded with differentiation operators, the sign function, and with floor, ceiling and a signed variant of the square root, respectively. We give an equational axiomatization of these operators and thus obtain a finite basis for various expanded cancellation meadows.; Comment: 24 pages, 6 tables; Inge Bethke is added as an extra author; new title (previous title: A Generic Basis Theorem for Cancellation Meadows)

Multipath Parameter Estimation from OFDM Signals in Mobile Channels

Letzepis, Nick; Grant, Alex; Alexander, Paul; Haley, David
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
17.474849%
We study multipath parameter estimation from orthogonal frequency division multiplex signals transmitted over doubly dispersive mobile radio channels. We are interested in cases where the transmission is long enough to suffer time selectivity, but short enough such that the time variation can be accurately modeled as depending only on per-tap linear phase variations due to Doppler effects. We therefore concentrate on the estimation of the complex gain, delay and Doppler offset of each tap of the multipath channel impulse response. We show that the frequency domain channel coefficients for an entire packet can be expressed as the superimposition of two-dimensional complex sinusoids. The maximum likelihood estimate requires solution of a multidimensional non-linear least squares problem, which is computationally infeasible in practice. We therefore propose a low complexity suboptimal solution based on iterative successive and parallel cancellation. First, initial delay/Doppler estimates are obtained via successive cancellation. These estimates are then refined using an iterative parallel cancellation procedure. We demonstrate via Monte Carlo simulations that the root mean squared error statistics of our estimator are very close to the Cramer-Rao lower bound of a single two-dimensional sinusoid in Gaussian noise.; Comment: Submitted to IEEE Transactions on Wireless Communications (26 pages...

Square-root cancellation for the signs of Latin squares

Alpoge, Levent
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/12/2014 Português
Relevância na Pesquisa
26.849507%
Let $L(n)$ be the number of Latin squares of order $n$, and let $L^{\textrm{even}}(n)$ and $L^{\textrm{odd}}(n)$ be the number of even and odd such squares, so that $L(n) = L^{\textrm{even}}(n) + L^{\textrm{odd}}(n)$. The Alon-Tarsi conjecture states that $L^{\textrm{even}}(n)\neq L^{\textrm{odd}}(n)$ when $n$ is even (when $n$ is odd the two are equal for very simple reasons). In this short note we prove that $|L^{\textrm{even}}(n) - L^{\textrm{odd}}(n)|\leq L(n)^{\frac{1}{2} + o(1)},$ thus establishing the conjecture that the number of even and odd Latin squares, while conjecturally not equal in even dimensions, are equal to leading order asymptotically. Two proofs are given: both proceed by applying a differential operator to an exponential integral over $\mathrm{SU}(n)$. The method is inspired by a recent result of Kumar-Landsberg.; Comment: 4 pages

An efficient square-root algorithm for BLAST

Hassibi, Babak
Fonte: IEEE Publicador: IEEE
Tipo: Book Section; PeerReviewed Formato: application/pdf
Publicado em //2000 Português
Relevância na Pesquisa
27.758032%
Bell Labs Layered Space-Time (BLAST) is a scheme for transmitting information over a rich-scattering wireless environment using multiple receive and transmit antennas. The main computational bottleneck in the BLAST algorithm is a “nulling and cancellation” step, where the optimal ordering for the sequential estimation and detection of the received signals is determined. To reduce the computational cost of BLAST, we develop an efficient square-root algorithm for the nulling and cancellation step. The main features of the algorithm include efficiency: the computational cost is reduced by 0.7 M, where M is the number of transmit antennas, and numerical stability: the algorithm is division-free and uses only orthogonal transformations. In a 14 antenna system designed for transmission of 1 Mbit/s over a 30 kHz channel, the nulling and cancellation computation is reduced from 190 MFlops/s to 19 MFlops/s, with the overall computations being reduced from 220 MFlops/s to 49 MFlops/s. The numerical stability of the algorithm also make it attractive for implementation in fixed-point (rather than floating-point) architectures.

A fast square-root implementation for BLAST

Hassibi, Babak
Fonte: IEEE Publicador: IEEE
Tipo: Book Section; PeerReviewed Formato: application/pdf
Publicado em //2000 Português
Relevância na Pesquisa
27.758032%
Bell Labs Layered Space-Time (BLAST) is a scheme for transmitting information over a rich-scattering wireless environment using multiple receive and transmit antennas. The main computational bottleneck in the BLAST algorithm is a "nulling and cancellation" step, where the optimal ordering for the sequential estimation and detection of the received signals is determined. To reduce the computational cost of BLAST we develop an efficient square-root algorithm for the nulling and cancellation step. The main features of the algorithm include efficiency: the computational cost is reduced by 0.7M, where M is the number of transmit antennas, and numerical stability; and the algorithm is division-free and uses only orthogonal transformations. In a 14 antenna system designed for transmission of 1 Mbit/sec over a 30 kHz channel, the nulling and cancellation computation is reduced from 190 MFlops/sec to 19 MFlops/sec, with the overall computations being reduced from 220 MFlops/sec to 49 MFlops/sec. The numerical stability of the algorithm also make it attractive for implementation in fixed-point (rather than floating-point) architectures.