Wave vector modification of the infinite order sudden approximation
International Nuclear Information System (INIS)
Sachs, J.G.; Bowman, J.M.
1980-01-01
A simple method is proposed to modify the infinite order sudden approximation (IOS) in order to extend its region of quantitative validity. The method involves modifying the phase of the IOS scattering matrix to include a part calculated at the outgoing relative kinetic energy as well as a part calculated at the incoming kinetic energy. An immediate advantage of this modification is that the resulting S matrix is symmetric. We also present a closely related method in which the relative kinetic energies used in the calculation of the phase are determined from quasiclassical trajectory calculations. A set of trajectories is run with the initial state being the incoming state, and another set is run with the initial state being the outgoing state, and the average final relative kinetic energy of each set is obtained. One part of the S-operator phase is then calculated at each of these kinetic energies. We apply these methods to vibrationally inelastic collinear collisions of an atom and a harmonic oscillator, and calculate transition probabilities P/sub n/1→nf for three model systems. For systems which are sudden, or nearly so, the agreement with exact quantum close-coupling calculations is substantially improved over standard IOS ones when Δn=such thatub f/-n/sub i/ is large, and the corresponding transition probability is small, i.e., less than 0.1. However, the modifications we propose will not improve the accuracy of the IOS transition probabilities for any collisional system unless the standard form of IOS already gives at least qualitative agreement with exact quantal calculations. We also suggest comparisons between some classical quantities and sudden predictions which should help in determining the validity of the sudden approximation. This is useful when exact quantal data is not available for comparison
Wave vector modification of the infinite order sudden approximation
Sachs, Judith Grobe; Bowman, Joel M.
1980-10-01
A simple method is proposed to modify the infinite order sudden approximation (IOS) in order to extend its region of quantitative validity. The method involves modifying the phase of the IOS scattering matrix to include a part calculated at the outgoing relative kinetic energy as well as a part calculated at the incoming kinetic energy. An immediate advantage of this modification is that the resulting S matrix is symmetric. We also present a closely related method in which the relative kinetic energies used in the calculation of the phase are determined from quasiclassical trajectory calculations. A set of trajectories is run with the initial state being the incoming state, and another set is run with the initial state being the outgoing state, and the average final relative kinetic energy of each set is obtained. One part of the S-operator phase is then calculated at each of these kinetic energies. We apply these methods to vibrationally inelastic collinear collisions of an atom and a harmonic oscillator, and calculate transition probabilities Pn1→nf for three model systems. For systems which are sudden, or nearly so, the agreement with exact quantum close-coupling calculations is substantially improved over standard IOS ones when Δn=‖nf-ni‖ is large, and the corresponding transition probability is small, i.e., less than 0.1. However, the modifications we propose will not improve the accuracy of the IOS transition probabilities for any collisional system unless the standard form of IOS already gives at least qualitative agreement with exact quantal calculations. We also suggest comparisons between some classical quantities and sudden predictions which should help in determining the validity of the sudden approximation. This is useful when exact quantal data is not available for comparison.
Two angle dependent reactive infinite order sudden approximation
International Nuclear Information System (INIS)
Jellinek, J.; Kouri, D.J.
1984-01-01
The reactive infinite order sudden approximation is redeveloped in a manner in which the initial and final arrangement internal angles γ/sub lambda/ amd γ/sub ν/ enter as independent quantities. The analysis follows parallel to that due to Khare, Kouri, and Baer except that matching of the wave function from different arrangements is done in a manner such that no single γ/sub ν/ angle is associated with a particular γ/sub lambda/ angle. As a consequence, the matching surface parameter B/sub lambdanu/ does not occur
Approximations of time-dependent phenomena in quantum mechanics: adiabatic versus sudden processes
International Nuclear Information System (INIS)
Melnichuk, S V; Dijk, W van; Nogami, Y
2005-01-01
By means of a one-dimensional model of a particle in an infinite square-well potential with one wall moving at a constant speed, we examine aspects of time-dependent phenomena in quantum mechanics such as adiabatic and sudden processes. The particle is assumed to be initially in the ground state of the potential with its initial width. The time dependence of the wavefunction of the particle in the well is generally more complicated when the potential well is compressed than when it is expanded. We are particularly interested in the case in which the potential well is suddenly compressed. The so-called sudden approximation is not applicable in this case. We also study the energy of the particle in the changing well as a function of time for expansion and contraction as well as for expansion followed by contraction and vice versa
Calculation of the MSD two-step process with the sudden approximation
Energy Technology Data Exchange (ETDEWEB)
Yoshida, Shiro [Tohoku Univ., Sendai (Japan). Dept. of Physics; Kawano, Toshihiko [Kyushu Univ., Advanced Energy Engineering Science, Kasuga, Fukuoka (Japan)
2000-03-01
A calculation of the two-step process with the sudden approximation is described. The Green's function which connects the one-step matrix element to the two-step one is represented in {gamma}-space to avoid the on-energy-shell approximation. Microscopically calculated two-step cross sections are averaged together with an appropriate level density to give a two-step cross section. The calculated cross sections are compared with the experimental data, however the calculation still contains several simplifications at this moment. (author)
International Nuclear Information System (INIS)
Smith, N.; Pritchard, D.E.
1981-01-01
We have recently demonstrated that the energy corrected sudden (ECS) scaling law of De Pristo et al. when conbined with the power law assumption for the basis rates k/sub l/→0proportional[l(l+1)]/sup -g/ can accurately fit a wide body of rotational energy transfer data. We develop a simple and accurate approximation to this fitting law, and in addition mathematically show the connection between it and our earlier proposed energy based law which also has been successful in describing both theoretical and experimental data on rotationally inelastic collisions
Examining the accuracy of the infinite order sudden approximation using sensitivity analysis
International Nuclear Information System (INIS)
Eno, L.; Rabitz, H.
1981-01-01
A method is developed for assessing the accuracy of scattering observables calculated within the framework of the infinite order sudden (IOS) approximation. In particular, we focus on the energy sudden assumption of the IOS method and our approach involves the determination of the sensitivity of the IOS scattering matrix S/sup IOS/ with respect to a parameter which reintroduces the internal energy operator h 0 into the IOS Hamiltonian. This procedure is an example of sensitivity analysis of missing model components (h 0 in this case) in the reference Hamiltonian. In contrast to simple first-order perturbation theory a finite result is obtained for the effect of h 0 on S/sup IOS/. As an illustration, our method of analysis is applied to integral state-to-state cross sections for the scattering of an atom and rigid rotor. Results are generated within the He+H 2 system and a comparison is made between IOS and coupled states cross sections and the corresponding IOS sensitivities. It is found that the sensitivity coefficients are very useful indicators of the accuracy of the IOS results. Finally, further developments and applications are discussed
Examining the accuracy of the infinite order sudden approximation using sensitivity analysis
Eno, Larry; Rabitz, Herschel
1981-08-01
A method is developed for assessing the accuracy of scattering observables calculated within the framework of the infinite order sudden (IOS) approximation. In particular, we focus on the energy sudden assumption of the IOS method and our approach involves the determination of the sensitivity of the IOS scattering matrix SIOS with respect to a parameter which reintroduces the internal energy operator ?0 into the IOS Hamiltonian. This procedure is an example of sensitivity analysis of missing model components (?0 in this case) in the reference Hamiltonian. In contrast to simple first-order perturbation theory a finite result is obtained for the effect of ?0 on SIOS. As an illustration, our method of analysis is applied to integral state-to-state cross sections for the scattering of an atom and rigid rotor. Results are generated within the He+H2 system and a comparison is made between IOS and coupled states cross sections and the corresponding IOS sensitivities. It is found that the sensitivity coefficients are very useful indicators of the accuracy of the IOS results. Finally, further developments and applications are discussed.
Extended sudden approximation model for high-energy nucleon removal reactions
Energy Technology Data Exchange (ETDEWEB)
Carstoiu, F.; Sauvan, E.; Orr, N.A. [Caen Univ., Lab. de Physique Corpusculaire, Institut des Sciences de la Matiere et du Rayonnement, IN2P3-CNRS ISMRA, 14 (France); Carstoiu, F. [IFIN-HH, Bucharest-Magurele (Romania); Bonaccorso, A. [Istituto Nazionale di Fisica Nucleare, Pisa (Italy)
2004-04-01
A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of {sup 17}C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored. (authors)
Extended sudden approximation model for high-energy nucleon removal reactions
International Nuclear Information System (INIS)
Carstoiu, F.; Sauvan, E.; Orr, N.A.; Carstoiu, F.; Bonaccorso, A.
2004-04-01
A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of 17 C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored. (authors)
International Nuclear Information System (INIS)
Baer, M.; Nakamura, H.; Kouri, D.J.
1986-01-01
In this work the ion-molecule reaction He + H 2 + (v/sub i/) → HeH + (v/sub f/) + H(v/sub i/ = 0-7, v/sub f/ = 0-2) was studied quantum mechanically in the energy range 1.3 eV ≤ E/sub tot/ ≤ 1.8 eV. The calculations were carried out employing the Reactive Infinite Order Sudden Approximation (RIOSA). The two features characteristic of this system in the above energy range, namely the strong enhancement of the reaction rate with the initial vibrational energy (at a fixed total energy) and the relatively weak dependence of the cross sections on translational energy, were found to be well reproduced in the numerical treatment. The results also revealed the existence of two mechanisms of the exchange process: one is the ordinary mechanism and the other is probably related to the spectator stripping model
Accuracy of the centrifugal sudden approximation in the H + CHD3 → H2 + CD3 reaction
International Nuclear Information System (INIS)
Zhang, Zhaojun; Chen, Jun; Liu, Shu; Zhang, Dong H.
2014-01-01
The initial state selected time-dependent wave packet method has been extended to calculate the coupled-channel reaction probabilities with total angular momentum J tot > 0 for the title reaction with seven degrees of freedom included. Fully converged integral cross sections were obtained for the ground and a number of vibrational excited initial states on a new potential energy surface recently constructed by this group using neural network fitting. As found from a previous study with the centrifugal sudden (CS) approximation, all these initial vibrational excitations investigated in this study enhance the reactivity considerably at a given collision energy, in particular the CH stretch excited state. The energy initially deposited in CH stretch motion is more effective than translational energy on promoting the reaction in the entire energy region, while for CH bending or CD 3 umbrella excitations only at the high collision energy the vibrational energy becomes more effective. Our calculations also revealed that the accuracy of the CS approximation considerably deteriorates with the increase of J tot , in particular on the threshold energy. The CS approximation underestimates the integral cross sections for all these initial states, albeit not very severely. In general, it works better at high collision energies and for vibrationally excited initial states, with the increase of integral cross section
Hypokalemia and sudden cardiac death
DEFF Research Database (Denmark)
Kjeldsen, Keld
2010-01-01
Worldwide, approximately three million people suffer sudden cardiac death annually. These deaths often emerge from a complex interplay of substrates and triggers. Disturbed potassium homeostasis among heart cells is an example of such a trigger. Thus, hypokalemia and, also, more transient...... of fatal arrhythmia and sudden cardiac death a patient is, the more attention should be given to the potassium homeostasis....
Sudden Stratospheric Warming Compendium
National Oceanic and Atmospheric Administration, Department of Commerce — Sudden Stratospheric Warming Compendium (SSWC) data set documents the stratospheric, tropospheric, and surface climate impacts of sudden stratospheric warmings. This...
... cornea (the clear layer in front of the iris and pupil), then the lens, and then the ... sudden start of symptoms may instead be sudden recognition. For example, a person with long-standing reduced ...
Ceelen, Manon; van der Werf, Christian; Hendrix, Anneke; Naujocks, Tatjana; Woonink, Frits; de Vries, Philip; van der Wal, Allard; Das, Kees
2015-01-01
The goal of this study was to ascertain accordance between cause of death established by the forensic physician and autopsy results in young sudden death victims in the Netherlands. Sudden death victims aged 1-45 years examined by forensic physicians operating in the participating regions which also
Directory of Open Access Journals (Sweden)
Neeraj Parakh
2015-01-01
Full Text Available Sudden cardiac death is one of the most common cause of mortality worldwide. Despite significant advances in the medical science, there is little improvement in the sudden cardiac death related mortality. Coronary artery disease is the most common etiology behind sudden cardiac death, in the above 40 years population. Even in the apparently healthy population, there is a small percentage of patients dying from sudden cardiac death. Given the large denominator, this small percentage contributes to the largest burden of sudden cardiac death. Identification of this at risk group among the apparently healthy individual is a great challenge for the medical fraternity. This article looks into the causes and methods of preventing SCD and at some of the Indian data. Details of Brugada syndrome, Long QT syndrome, Genetics of SCD are discussed. Recent guidelines on many of these causes are summarised.
Geomagnetic Storm Sudden Commencements
National Oceanic and Atmospheric Administration, Department of Commerce — Storm Sudden Commencements (ssc) 1868 to present: STORM1 and STORM2 Lists: (Some text here is taken from the International Association of Geomagnetism and Aeronomy...
Sudden Ionospheric Disturbances (SID)
National Oceanic and Atmospheric Administration, Department of Commerce — Sudden ionospheric disturbances (SID) are caused by solar flare enhanced X-rays in the 1 to 10 angstrom range. Solar flares can produce large increases of ionization...
Sport and sudden death in children
Directory of Open Access Journals (Sweden)
L. M. Makarov
2017-01-01
Full Text Available The article presents data on contemporary views of the prevalence, causes, circumstances of sudden cardiac death, and its prevention measures in children and adolescents during sports activity. It notes a difficulty in defining the epidemiology of the above condition because the data are primarily based upon mass media news coverage. The incidence of sudden cardiac death is approximately 1 per 100,000 young athletes; more than 90% boys die. The sports, during which sudden cardiac death often occurs, include (both American and European football, basketball, and hockey. Sudden cardiac death due to cоmmоtio cordis (life-threatening cardiac arrhythmias resulting from a blow with a blunt instrument to the area of the heart during the vulnerable phase of the cardiac cycle is considered separately. Children who die suddenly during sports are frequently detected to have hypertrophic cardiomyopathy or myocarditis; but no changes are found in more than 50% of cases at autopsy, which is suggestive of primary arrhythmogenic death. The basis for prevention is the early detection of diseases that can cause sudden death during sports, regular examination, knowledge of ECG characteristics in athletes, and first aid techniques, including the use of automated external defibrillators.
The sudden death and sudden birth of quantum discord.
Xia, Wei; Hou, Jin-Xing; Wang, Xiao-Hui; Liu, Si-Yuan
2018-03-28
The interaction of quantum system and its environment brings out abundant quantum phenomenons. The sudden death of quantum resources, including entanglement, quantum discord and coherence, have been studied from the perspective of quantum breaking channels (QBC). QBC of quantum resources reveal the common features of quantum resources. The definition of QBC implies the relationship between quantum resources. However, sudden death of quantum resources can also appear under some other quantum channels. We consider the dynamics of Bell-diagonal states under a stochastic dephasing noise along the z-direction, and the sudden death and sudden birth of quantum discord are investigated. Next we explain this phenomenon from the geometric structure of quantum discord. According to the above results, the states with sudden death and sudden birth can be filtered in three-parameter space. Then we provide two necessary conditions to judge which kind of noise channels can make Bell-diagonal states sudden death and sudden birth. Moreover, the relation between quantum discord and coherence indicates that the sudden death and sudden birth of quantum discord implies the sudden death and sudden birth of coherence in an optimal basis.
Sudden Infant Death Syndrome (SIDS)
Sudden infant death syndrome (SIDS) Overview Sudden infant death syndrome (SIDS) is the unexplained death, usually during sleep, of a seemingly healthy baby ... year old. SIDS is sometimes known as crib death because the infants often die in their cribs. ...
DEFF Research Database (Denmark)
Risgaard, Bjarke; Winkel, Bo Gregers; Jabbari, Reza
2017-01-01
Objectives This study sought to describe the use of pharmacotherapy in a nationwide cohort of young patients with sudden cardiac death (SCD). Background Several drugs have been associated with an increased risk of SCD and sudden arrhythmic death syndrome (SADS). It remains unclear how...... pharmacotherapy may contribute to the overall burden of SCD in the general population. Methods This was a nationwide study that included all deaths that occurred between 2000 and 2009 and between 2007 and 2009 in people age 1 to 35 years and 36 to 49 years, respectively. Two physicians identified all SCDs through...... review of death certificates. Autopsy reports were collected. Pharmacotherapy prescribed within 90 days before SCD was identified in the Danish Registry of Medicinal Product Statistics. Results We identified 1,363 SCDs; median age was 38 years (interquartile range: 29 to 45 years), and 72% (n = 975) were men...
[Sudden death from hypoglycemia].
Asmundo, A; Aragona, M; Gualniera, P; Aragona, F
1995-12-01
The sudden death by hypoglycemia is an aspect of the forensic pathology frequently neglected. Authors initially described the pathogenesis of different hypoglycemia forms, distinguishing the primary ones due to hyperinsulinism and the secondary ones due to functional insufficiency of other organs (hypophysis, thyroid, adrenal gland, liver); after that Authors described three cases of sudden death induced hypoglycemia by hyperinsulinism: two were unweaned with nesidioblastosis and one adolescent. In any form of hypoglycemia the central nervous system damage is present with evident neuronal degenerative-necrotic phenomena, widespread edema with microhemorrhage, swollen and dissociation of myelin sheath, glial cells hyperplasia. Death caused by primary hypoglycemia is histopathologically different from the secondary one because of the maintenance of hepatic glycogen content in the former, that increase in striated muscles, including the heart, in spite of the constant secretion of catecholamine from the adrenal medulla. Glycogen is depleted in secondary hypoglycemia. In the primary form, behind the adrenal medulla hyperfunction, the increased functional activity of the adrenal cortex is moderate, contrasting with the seriousness of the syndrome, due prevalently to inhibit the gluconeogenesis response conditioned by the persistence of stored glycogen in the liver, heart and striated muscles. The rare anoxic processes coming with resynthesis of hepatic glycogen have to be considered in the differential diagnosis. The primary hypoglycemic death, especially in unweaned, is frequently promoted by other processes inducing hypoxia (fetal asphyxia outcome, pneumonia, etc.) or worsening the hypoglycemia (hypothyroidism, etc.). The secondary hypoglycemias are characterized by the normality of exocrine pancreas and by organic alterations that cause glycogen depletion from the liver.
Sudden Event Recognition: A Survey
Directory of Open Access Journals (Sweden)
Mohd Asyraf Zulkifley
2013-08-01
Full Text Available Event recognition is one of the most active research areas in video surveillance fields. Advancement in event recognition systems mainly aims to provide convenience, safety and an efficient lifestyle for humanity. A precise, accurate and robust approach is necessary to enable event recognition systems to respond to sudden changes in various uncontrolled environments, such as the case of an emergency, physical threat and a fire or bomb alert. The performance of sudden event recognition systems depends heavily on the accuracy of low level processing, like detection, recognition, tracking and machine learning algorithms. This survey aims to detect and characterize a sudden event, which is a subset of an abnormal event in several video surveillance applications. This paper discusses the following in detail: (1 the importance of a sudden event over a general anomalous event; (2 frameworks used in sudden event recognition; (3 the requirements and comparative studies of a sudden event recognition system and (4 various decision-making approaches for sudden event recognition. The advantages and drawbacks of using 3D images from multiple cameras for real-time application are also discussed. The paper concludes with suggestions for future research directions in sudden event recognition.
Corrado, Domenico; Zorzi, Alessandro
2017-06-15
Competitive sports activity is associated with an increased risk of sudden cardiovascular death (SCD) in adolescents and young adults with clinically silent cardiovascular disorders. While in middle-aged/senior athletes atherosclerotic coronary artery disease accounts for the vast majority of SCDs, in young athletes the spectrum of substrates is wider and includes inherited (cardiomyopathies) and congenital (anomalous origin of coronary arteries) structural heart diseases. Inherited ion channel diseases have been implicated in SCDs occurring with an apparently normal heart at autopsy. Screening including the ECG allows identification of athletes affected by heart muscle diseases at a pre-symptomatic stage and may lead to reduction of the risk of SCD during sports. The use of modern criteria for interpretation of the ECG in the athlete offers the potential to improve the screening accuracy by reducing the number of false positives. Screening with exercise testing middle aged/senior athletes engaged in leisure sports activity is likely to be effective in patients with significant coronary risk factors, while it is not useful in low-risk subgroups. The availability of automated external defibrillator on the athletic field provides a "back-up" preventive strategy for unpredictable arrhythmic cardiac arrest, mostly occurring in patients with coronary artery diseases. Copyright © 2017. Published by Elsevier B.V.
Sudden transition and sudden change from open spin environments
International Nuclear Information System (INIS)
Hu, Zheng-Da; Xu, Jing-Bo; Yao, Dao-Xin
2014-01-01
We investigate the necessary conditions for the existence of sudden transition or sudden change phenomenon for appropriate initial states under dephasing. As illustrative examples, we study the behaviors of quantum correlation dynamics of two noninteracting qubits in independent and common open spin environments, respectively. For the independent environments case, we find that the quantum correlation dynamics is closely related to the Loschmidt echo and the dynamics exhibits a sudden transition from classical to quantum correlation decay. It is also shown that the sudden change phenomenon may occur for the common environment case and stationary quantum discord is found at the high temperature region of the environment. Finally, we investigate the quantum criticality of the open spin environment by exploring the probability distribution of the Loschmidt echo and the scaling transformation behavior of quantum discord, respectively. - Highlights: • Sudden transition or sudden change from open spin baths are studied. • Quantum discord is related to the Loschmidt echo in independent open spin baths. • Steady quantum discord is found in a common open spin bath. • The probability distribution of the Loschmidt echo is analyzed. • The scaling transformation behavior of quantum discord is displayed
Sudden cardiac death in athletes
Directory of Open Access Journals (Sweden)
Fábio Camilo Pellegrino dos Santos
2012-11-01
Full Text Available ABSTRACT The most accepted definition of sudden cardiac death nowadays is an unexplained death occurred suddenly within one hour of symptom onset. If it was not witnessed, individuals need to had been observed for at least 24 hours before the event and should be discarded the possibility of non cardiac causes of sudden death, pulmonary embolism or extensive malignancy. The term athlete refers to individuals of any age who participate in collective or individual regular physical activity, as well as physical training program for regular competitions. The sudden death of a young athlete, whether amateur or professional, especially during competitions, is always dramatic, with strong negative social impact and in the media. The fact that sports are recommended as a formula for longevity and quality of life makes these events a cause for concern in sports and society in general.
Sudden death in eating disorders
Directory of Open Access Journals (Sweden)
Jáuregui-Garrido B
2012-02-01
Full Text Available Beatriz Jáuregui-Garrido1, Ignacio Jáuregui-Lobera2,31Department of Cardiology, University Hospital Virgen del Rocío, 2Behavioral Sciences Institute, 3Pablo de Olavide University, Seville, SpainAbstract: Eating disorders are usually associated with an increased risk of premature death with a wide range of rates and causes of mortality. “Sudden death” has been defined as the abrupt and unexpected occurrence of fatality for which no satisfactory explanation of the cause can be ascertained. In many cases of sudden death, autopsies do not clarify the main cause. Cardiovascular complications are usually involved in these deaths. The purpose of this review was to report an update of the existing literature data on the main findings with respect to sudden death in eating disorders by means of a search conducted in PubMed. The most relevant conclusion of this review seems to be that the main causes of sudden death in eating disorders are those related to cardiovascular complications. The predictive value of the increased QT interval dispersion as a marker of sudden acute ventricular arrhythmia and death has been demonstrated. Eating disorder patients with severe cardiovascular symptoms should be hospitalized. In general, with respect to sudden death in eating disorders, some findings (eg, long-term eating disorders, chronic hypokalemia, chronically low plasma albumin, and QT intervals >600 milliseconds must be taken into account, and it must be highlighted that during refeeding, the adverse effects of hypophosphatemia include cardiac failure. Monitoring vital signs and performing electrocardiograms and serial measurements of plasma potassium are relevant during the treatment of eating disorder patients.Keywords: sudden death, cardiovascular complications, refeeding syndrome, QT interval, hypokalemia
Investigating Insight as Sudden Learning
Ash, Ivan K.; Jee, Benjamin D.; Wiley, Jennifer
2012-01-01
Gestalt psychologists proposed two distinct learning mechanisms. Associative learning occurs gradually through the repeated co-occurrence of external stimuli or memories. Insight learning occurs suddenly when people discover new relationships within their prior knowledge as a result of reasoning or problem solving processes that re-organize or…
Sudden entanglement death, and ways to avoid it
International Nuclear Information System (INIS)
Eberly, J.H.; Ting Yu
2005-01-01
We report that non-communicating but entangled qubit pairs are almost universally liable to sudden entanglement death. In the presence of minor and purely local environmental noises their mixed-state entanglement may abruptly become zero long before the noises are able to destroy the local qubit coherence. Despite the inability of unitary transformations to alter entanglement, for example of Werner states, unitary transformations have been found to delay or defeat the sudden death event. These results upset the conventional understanding that entanglement lifetime can be estimated from qubit lifetime. This is not even approximately or qualitatively true. (author)
[Psychological stress and sudden death].
Pignalberi, Carlo; Ricci, Renato; Santini, Massimo
2002-10-01
Recent studies provide relevant evidence that psychological stress significantly influences the pathogenesis of sudden cardiac death. Psychological stress expresses a situation of imbalance, derived from a real or perceived disparity between environmental demands and the individual's ability to cope with these demands. A situation of psychological stress may include different components: personality factors and character traits, anxiety and depression, social isolation and acute or chronic adverse life events. In particular, it has been documented that a sudden extremely hard event, such as an earthquake or a war strike, can significantly increase the incidence of sudden death. Nevertheless, each one of these factors, if not present, can balance a partially unfavorable situation; this overview suggests a multifactorial situation where almost all elements are present and in which the relative influence of each one varies according to the individual examined. Sudden death occurs when a transient disruption (such as acute myocardial ischemia, platelet activation or neuroendocrine variations), occurring in a patient with a diseased myocardium (such as one with a post-necrotic scar or hypertrophy), triggers a malignant arrhythmia. Psychological stress acts at both levels: by means of a "chronic" action it contributes to create the myocardial background, while by means of an acute action it can create the transient trigger precipitating sudden death. In the chronic action two possible mechanisms can be detected: the first is a direct interaction, which contributes to cause a hypertension status or to exacerbate coronary atherosclerosis consequent to endothelial dysfunction; the second one acts through adverse health behaviors, such as a poor diet, alcohol consumption or smoking. In case of acute psychological stress, the mechanisms involved are mainly the ability to trigger myocardial ischemia, to promote arrhythmogenesis, to stimulate platelet function, and to increase
CERN. Geneva
2015-01-01
Most physics results at the LHC end in a likelihood ratio test. This includes discovery and exclusion for searches as well as mass, cross-section, and coupling measurements. The use of Machine Learning (multivariate) algorithms in HEP is mainly restricted to searches, which can be reduced to classification between two fixed distributions: signal vs. background. I will show how we can extend the use of ML classifiers to distributions parameterized by physical quantities like masses and couplings as well as nuisance parameters associated to systematic uncertainties. This allows for one to approximate the likelihood ratio while still using a high dimensional feature vector for the data. Both the MEM and ABC approaches mentioned above aim to provide inference on model parameters (like cross-sections, masses, couplings, etc.). ABC is fundamentally tied Bayesian inference and focuses on the “likelihood free” setting where only a simulator is available and one cannot directly compute the likelihood for the dat...
Schmidt, Wolfgang M
1980-01-01
"In 1970, at the U. of Colorado, the author delivered a course of lectures on his famous generalization, then just established, relating to Roth's theorem on rational approxi- mations to algebraic numbers. The present volume is an ex- panded and up-dated version of the original mimeographed notes on the course. As an introduction to the author's own remarkable achievements relating to the Thue-Siegel-Roth theory, the text can hardly be bettered and the tract can already be regarded as a classic in its field."(Bull.LMS) "Schmidt's work on approximations by algebraic numbers belongs to the deepest and most satisfactory parts of number theory. These notes give the best accessible way to learn the subject. ... this book is highly recommended." (Mededelingen van het Wiskundig Genootschap)
Mutations in calmodulin cause ventricular tachycardia and sudden cardiac death
DEFF Research Database (Denmark)
Nyegaard, Mette; Overgaard, Michael Toft; Sondergaard, M.T.
2012-01-01
a substantial part of sudden cardiac deaths in young individuals. Mutations in RYR2, encoding the cardiac sarcoplasmic calcium channel, have been identified as causative in approximately half of all dominantly inherited CPVT cases. Applying a genome-wide linkage analysis in a large Swedish family with a severe......Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a devastating inherited disorder characterized by episodic syncope and/or sudden cardiac arrest during exercise or acute emotion in individuals without structural cardiac abnormalities. Although rare, CPVT is suspected to cause...... calmodulin-binding-domain peptide at low calcium concentrations. We conclude that calmodulin mutations can cause severe cardiac arrhythmia and that the calmodulin genes are candidates for genetic screening of individual cases and families with idiopathic ventricular tachycardia and unexplained sudden cardiac...
Sudden Cardiac Arrest (SCA) Risk Assessment
... HRS Find a Specialist Share Twitter Facebook SCA Risk Assessment Sudden Cardiac Arrest (SCA) occurs abruptly and without ... people of all ages and health conditions. Start Risk Assessment The Sudden Cardiac Arrest (SCA) Risk Assessment Tool ...
Dynamic stability under sudden loads
International Nuclear Information System (INIS)
Simitses, G.J.
1998-01-01
The concept of dynamic stability of elastic structures subjected to sudden (step) loads is discussed. The various criteria and related methodologies for estimating critical conditions are presented with the emphasis on their similarities and differences. These are demonstrated by employing a simple mechanical model. Several structural configurations are analyzed, for demonstration purposes, with the intention of comparing critical dynamic loads to critical static loads. These configurations include shallow arches and shallow spherical caps, two bar frames, and imperfect cylindrical shells of metallic as well as laminated composite construction. In the demonstration examples, the effect of static pre loading on the dynamic critical load is presented
Magnus approximation in the adiabatic picture
International Nuclear Information System (INIS)
Klarsfeld, S.; Oteo, J.A.
1991-01-01
A simple approximate nonperturbative method is described for treating time-dependent problems that works well in the intermediate regime far from both the sudden and the adiabatic limits. The method consists of applying the Magnus expansion after transforming to the adiabatic basis defined by the eigenstates of the instantaneous Hamiltonian. A few exactly soluble examples are considered in order to assess the domain of validity of the approximation. (author) 32 refs., 4 figs
Sudden cardiac death in young athletes
Directory of Open Access Journals (Sweden)
Östman-Smith I
2011-07-01
Full Text Available Ingegerd Östman-SmithDivision of Paediatric Cardiology, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg University, SwedenAbstract: Athletic activity is associated with an increased risk of sudden death for individuals with some congenital or acquired heart disorders. This review considers in particular the causes of death affecting athletes below 35 years of age. In this age group the largest proportion of deaths are caused by diseases with autosomal dominant inheritance such as hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, long QT-syndrome, and Marfan’s syndrome. A policy of early cascade-screening of all first-degree relatives of patients with these disorders will therefore detect a substantial number of individuals at risk. A strictly regulated system with preparticipation screening of all athletes following a protocol pioneered in Italy, including school-age children, can also detect cases caused by sporadic new mutations and has been shown to reduce excess mortality among athletes substantially. Recommendations for screening procedure are reviewed. It is concluded that ECG screening ought to be part of preparticipation screening, but using criteria that do not cause too many false positives among athletes. One such suggested protocol will show positive in approximately 5% of screened individuals, among whom many will be screened for these diseases. On this point further research is needed to define what kind of false-positive and false-negative rate these new criteria result in. A less formal system based on cascade-screening of relatives, education of coaches about suspicious symptoms, and preparticipation questionnaires used by athletic clubs, has been associated over time with a sizeable reduction in sudden cardiac deaths among Swedish athletes, and thus appears to be worth implementing even for junior athletes not recommended for formal preparticipation screening. It is strongly argued
DEFF Research Database (Denmark)
Larsen, T B; Nørgaard-Pedersen, B; Banner, Jytte
2000-01-01
in the child. This prompted us to investigate these genetic markers of thromboembolic disease in 121 cases of sudden infant death syndrome and in relevant controls, in the expectation of a more frequent occurrence of these markers if thrombosis is an etiological factor in sudden infant death syndrome......Sudden infant death syndrome or "cot death" has until the late eighties been a significant cause of death in children between the ages of 1 month and 1 year. Approximately two per 1000 children born alive dies of sudden infant death syndrome each year in Western Europe, North America, and Australia....... The vulnerability of the infant brain stem to ischemia has been suggested to be a conceivable cause of sudden infant death syndrome. This is compatible with a hypothesis that genetic risk factors for cerebral thrombosis could cause microinfarction in the brain stem during the first month of life, affecting vital...
Controllable entanglement sudden birth of Heisenberg spins
International Nuclear Information System (INIS)
Zheng Qiang; Zhi Qijun; Zhang Xiaoping; Ren Zhongzhou
2011-01-01
We investigate the Entanglement Sudden Birth (ESB) of two Heisenberg spins A and B. The third controller, qutrit C is introduced, which only has the Dzyaloshinskii-Moriya (DM) spin-orbit interaction with qubit B. We find that the DM interaction is necessary to induce the Entanglement Sudden Birth of the system qubits A and B, and the initial states of the system qubits and the qutrit C are also important to control its Entanglement Sudden Birth. (authors)
Fragmentation of suddenly heated liquids
International Nuclear Information System (INIS)
Blink, J.A.
1985-03-01
Fragmentation of free liquids in Inertial Confinement Fusion reactors could determine the upper bound on reactor pulse rate. The x-ray ablated materials must cool and recondense to allow driver beam propagation. The increased surface area caused by fragmentation will enhance the cooling and condensation rates. Relaxation from the suddenly heated state will move a liquid into the negative pressure region under the liquid-vapor P-V dome. The lithium equation of state was used to demonstrate that neutron-induced vaporization uses only a minor fraction of the added heat, much less than would be required to drive the expansion. A 77% expansion of the lithium is required before the rapid vaporization process of spinodal decomposition could begin, and nucleation and growth are too slow to contribute to the expansion
DEFF Research Database (Denmark)
Mortensen, Lars Boje
2017-01-01
The article presents a new model for understanding the sudden success of prose in four literatures: Greek, Latin, French and Old Norse. Through comparison and quantitative observations, and by focusing on the success of prose rather than its invention, it is shown that in all four cases two...... reading aloud) has been underplayed in previous scholarship mostly focused on authorial choices and invention. For two of the literatures (Greek, French) the fast dynamics of the rise of prose has already been identified and discussed, but for the two others (Latin, Old Norse), the observation is new....... It is also suggested that the exactly contemporary rise of French and Old Norse prose (c. 1200-1230) most probably is connected. The four literatures are each shown in chronological charts so as to visualize the timeline and the relation between poetic and prosaic works. The article furthermore reflects...
Brugada Syndrome in a Patient with Vascular Ehlers-Danlos Syndrome: Sudden Death Risk Amplified.
D'Souza, Jason; Malhotra, Divyanshu; Goud, Aditya; Dahagam, Chanukya; Everett, George
2017-04-19
The vast majority of sudden cardiac arrests occur in patients with structural heart disease and in approximately 10% of the cases, it can occur in those with structurally normal hearts. Brugada syndrome is an autosomal dominant sodium channelopathy that has been implicated in sudden deaths. Given their low prevalence, our knowledge about Brugada syndrome is still evolving. Apart from schizophrenia, there have been no reports of associated medical conditions. We recently encountered a patient with vascular Ehlers-Danlos syndrome who was also found to have Brugada syndrome. Both these conditions share some common clinical presentations including a propensity for sudden death.
Sudden Cardiac Death in Children. Part 2
Directory of Open Access Journals (Sweden)
Ye.V. Pshenichnaya
2013-03-01
Full Text Available This article deals with the dysplastic changes in musculo-valve structures of the heart, arrhythmias and conduction disorders, associated with a risk of sudden cardiac death. The diagnostic criteria for sudden cardiac death, the events of cardio-pulmonary resuscitation, prevention of life-threatening conditions in children are provided.
Sudden Cardiac Death in Children. Part 1
Directory of Open Access Journals (Sweden)
Ye.V. Pshenichnaya
2013-02-01
Full Text Available This article presents the prevalence, terminology, classification of sudden cardiac death. A description of congenital structural heart diseases associated with a risk of sudden cardiac death is given. The issues of etiology and pathogenesis of life-threatening conditions are described in detail.
Athletes at Risk for Sudden Cardiac Death
Subasic, Kim
2010-01-01
High school athletes represent the largest group of individuals affected by sudden cardiac death, with an estimated incidence of once or twice per week. Structural cardiovascular abnormalities are the most frequent cause of sudden cardiac death. Athletes participating in basketball, football, track, soccer, baseball, and swimming were found to…
Sudden bilateral hearing loss after organophosphate inhalation
Directory of Open Access Journals (Sweden)
Mehmet Akif Dundar
2016-12-01
Full Text Available Sudden bilateral hearing loss are seen rarely and the toxic substance exposure constitutes a small part of etiology. A Fifty-eight-year-old woman admitted to our clinic with sudden bilateral hearing loss shortly after chlorpyrifos-ethyl exposure. Otolaryngologic examination findings were normal. The patient had 40 dB sensorineural hearing loss (SNHL on the right ear and 48 dB SNHL on the left ear. Additional diagnostic tests were normal. The conventional treatment for sudden hearing loss was performed. On the second week following organophosphate (OP exposure the patient's hearing loss almost completely resolved. OP's are heavily used in agriculture and should be taken into consideration as an etiologic factor in sudden hearing loss. Keywords: Organophosphates, Hearing loss, Sudden
Diophantine approximation and badly approximable sets
DEFF Research Database (Denmark)
Kristensen, S.; Thorn, R.; Velani, S.
2006-01-01
. The classical set Bad of `badly approximable' numbers in the theory of Diophantine approximation falls within our framework as do the sets Bad(i,j) of simultaneously badly approximable numbers. Under various natural conditions we prove that the badly approximable subsets of Omega have full Hausdorff dimension...
Supravalvular aortic stenosis with sudden cardiac death
Directory of Open Access Journals (Sweden)
Pradeep Vaideeswar
2015-01-01
Full Text Available Sudden cardiac death (SCD most commonly results from previously undiagnosed congenital, acquired, or hereditary cardiac diseases. Congenital aortic valvular, subvalvular, and supravalvular disease with left ventricular outflow tract obstruction is an important preventable cause of sudden death. This report documents sudden death presumably due to acute myocardial ischemia in a young male with an undiagnosed supravalvular aortic stenosis (SVAS due to a rare association of isolation of coronary sinuses of Valsalva. Congenital supravalvular pulmonary stenosis and mitral valvular dysplasia were also present.
Sudden Death in Young People--Heart Problems Often Blamed
Sudden death in young people: Heart problems often blamed Sudden death in young people is rare, but those at ... causes and treatments. By Mayo Clinic Staff Sudden death in people younger than 35, often due to ...
Directory of Open Access Journals (Sweden)
Jamie I. Vandenberg
2017-08-01
Full Text Available There have been tremendous advances in the diagnosis and treatment of heart disease over the last 50 years. Nevertheless, it remains the number one cause of death. About half of heart-related deaths occur suddenly, and in about half of these cases the person was unaware that they had underlying heart disease. Genetic heart disease accounts for only approximately 2% of sudden cardiac deaths, but as it typically occurs in younger people it has been a particular focus of activity in our quest to not only understand the underlying mechanisms of cardiac arrhythmogenesis but also develop better strategies for earlier detection and prevention. In this brief review, we will highlight trends in the recent literature focused on sudden cardiac death in genetic heart diseases and how these studies are contributing to a broader understanding of sudden death in the community.
Steroid Treatments Equally Effective Against Sudden Deafness
... NIGMS NIMH NIMHD NINDS NINR NLM CC CIT CSR FIC NCATS NCCIH OD About NIH Who We ... with sudden deafness should discuss the risks and benefits of both treatments with their doctor.” Related Links ...
Sudden unexpected death caused by stroke
DEFF Research Database (Denmark)
Ågesen, Frederik Nybye; Risgaard, Bjarke; Zachariasardóttir, Sára
2017-01-01
Background Stroke is the fifth leading cause of death in young individuals globally. Data on the burden of sudden death by stroke are sparse in the young. Aims The aim of this study was to report mortality rates, cause of death, stroke subtype, and symptoms in children and young adults who suffered....... There was a male predominance (56%) and the median age was 33 years. The incidence of sudden death by stroke in individuals aged 1-49 years was 0.19 deaths per 100,000 person-years. Stroke was hemorrhagic in 94% of cases, whereof subarachnoid hemorrhage was the cause of death in 63% of cases. Seventeen (33%) cases...... contacted the healthcare system because of neurological symptoms, whereof one was suspected of having a stroke (6%). Conclusions Sudden death by stroke in children and young adults occurs primarily due to hemorrhagic stroke. We report a high frequency of neurological symptoms prior to sudden death by stroke...
Sudden Sensorineural Hearing Loss; Prognostic Factors
Arjun, Dass; Neha, Goel; Surinder K, Singhal; Ravi, Kapoor
2015-01-01
Introduction: Sudden sensorineural hearing loss (SSNHL) is a frightening and frustrating symptom for the patient as well as the physician. Prognosis is affected by multiple factors including duration of hearing loss, presence of associated vertigo and tinnitus, and co-morbidities such as hypertension and diabetes. Materials and Methods: Forty subjects presenting to our department with features of sudden hearing loss were included in the study. Detailed otological history and examination, se...
Sudden Hearing Loss after Rabies Vaccination
Güçlü, Oğuz; Dereköy, Fevzi Sefa
2014-01-01
Background: Sudden hearing loss developing after immunisation is a very rare situation. Rabies is a viral disease characterised by encephalitis and death. Treatment involves active and passive immunisation. Neurologic complications including Guillain-Barre syndrome or facial paralysis are reported in the literature as a side effect after rabies immunisation. Case Report: Sudden hearing loss was detected in an 11 year-old male patient who had taken the medication for rabies immunisatio...
Sudden Hearing Loss after Rabies Vaccination
Güçlü, Oğuz; Dereköy, Fevzi Sefa
2013-01-01
Background: Sudden hearing loss developing after immunisation is a very rare situation. Rabies is a viral disease characterised by encephalitis and death. Treatment involves active and passive immunisation. Neurologic complications including Guillain-Barre syndrome or facial paralysis are reported in the literature as a side effect after rabies immunisation. Case Report: Sudden hearing loss was detected in an 11 year-old male patient who had taken the medication for rabies immunisat...
Sudden cardiac death in children and adolescents (excluding Sudden Infant Death Syndrome
Directory of Open Access Journals (Sweden)
Gajewski Kelly
2010-01-01
Full Text Available Sudden death in the young is rare. About 25% of cases occur during sports. Most young people with sudden cardiac death (SCD have underlying heart disease, with hypertrophic cardiomyopathy and coronary artery anomalies being commonest in most series. Arrhythmogenic right ventricular dysplasia and long QT syndrome are the most common primary arrhythmic causes of SCD. It is estimated that early cardiopulmonary resuscitation and widespread availability of automatic external defibrillators could prevent about a quarter of pediatric sudden deaths.
Exact scattering solutions in an energy sudden (ES) representation
International Nuclear Information System (INIS)
Chang, B.; Eno, L.; Rabitz, H.
1983-01-01
In this paper, we lay down the theoretical foundations for computing exact scattering wave functions in a reference frame which moves in unison with the system internal coordinates. In this frame the (internal) coordinates appear to be fixed and its adoption leads very naturally (in zeroth order) to the energy sudden (ES) approximation [and the related infinite order sudden (IOS) method]. For this reason we call the new representation for describing the exact dynamics of a many channel scattering problem, the ES representation. Exact scattering solutions are derived in both time dependent and time independent frameworks for the representation and many interesting results in these frames are established. It is shown, e.g., that in a time dependent frame the usual Schroedinger propagator factorizes into internal Hamiltonian, ES, and energy correcting propagators. We also show that in a time independent frame the full Green's functions can be similarly factorized. Another important feature of the new representation is that it forms a firm foundation for seeking corrections to the ES approximation. Thus, for example, the singularity which arises in conventional perturbative expansions of the full Green's functions (with the ES Green's function as the zeroth order solution) is avoided in the ES representation. Finally, a number of both time independent and time dependent ES correction schemes are suggested
Sudden unexpected death in infancy in Denmark
DEFF Research Database (Denmark)
Winkel, Bo Gregers; Holst, Anders Gaarsdal; Theilade, Juliane
2011-01-01
Abstract Background. Incidence of sudden unexpected death in infancy (SUDI) and sudden infant death syndrome (SIDS) differs among studies and non-autopsied cases are difficult to assess. Objectives. To investigate causes of sudden death in infancy in a nationwide setting. Validate the use...... of the ICD-10 code for SIDS (R95) in the Danish Cause of Death registry. Design. A retrospective analysis of all infant deaths (death certificates and autopsy reports were read. Results. We identified 192 SUDI cases (10% of total deaths, 0.42 per 1000 births......) with autopsy performed in 87% of cases. In total, 49% of autopsied SUDI cases were defined as SIDS (5% of all deaths, 0.22 per 1000 births); Cardiac cause of death was denoted in 24% of cases. The Danish Cause of Death Registry misclassified 30% of SIDS cases. Conclusions. A large proportion of infant deaths...
Sudden Gains during Therapy of Social Phobia
Hofmann, Stefan G.; Schultz, Stefan M.; Meuret, Alicia E.; Moscovitch, David A.; Suvak, Michael
2006-01-01
The present study investigated the phenomenon of sudden gains in 107 participants with social phobia (social anxiety disorder) who received either cognitive-behavioral group therapy or exposure group therapy without explicit cognitive interventions, which primarily used public speaking situations as exposure tasks. Twenty-two out of 967…
Cardiac channelopathies and sudden infant death syndrome
DEFF Research Database (Denmark)
Tfelt-Hansen, Jacob; Winkel, Bo Gregers; Grunnet, Morten
2011-01-01
Sudden infant death syndrome (SIDS) is always a devastating and unexpected occurrence. SIDS is the leading cause of death in the first 6 months after birth in the industrialized world. Since the discovery in 1998 of long QT syndrome as an underlying substrate for SIDS, around 10-20% of SIDS cases...
Sudden death syndrome of soybean in Argentina
Sudden death syndrome (SDS) is one of the most common and widely spread root disease affecting soybean [Glycine max (L.) Merr.] in Argentina where it is an economically important crop. This disease was first discovered in this country in 1992 in the Pampas Region, and the following year in Northwest...
Febrile convulsions and sudden infant death syndrome
DEFF Research Database (Denmark)
Vestergaard, Mogens; Basso, Olga; Henriksen, Tine Brink
2002-01-01
It has been suggested that sudden infant death syndrome (SIDS) and febrile convulsions are related aetiologically. We compared the risk of SIDS in 9877 siblings of children who had had febrile convulsions with that of 20.177 siblings of children who had never had febrile convulsions. We found...
Sudden Oak Death - Eastern (Pest Alert)
Joseph O' Brien; Manfred Mielke; Steve Oak; Bruce Moltzan
2002-01-01
A phenomenon known as Sudden Oak Death was first reported in 1995 in central coastal California. Since then, tens of thousands of tanoaks (Lithocarpus densiflorus), coast live oaks (Quercus agrifolia), and California black oaks (Quercus kelloggii) have been killed by a newly identified fungus, Phytophthora ramorum. On these hosts, the fungus causes a bleeding canker on...
Sudden (reversible) sensorineural hearing loss in pregnancy.
LENUS (Irish Health Repository)
Kenny, R
2011-03-01
Sudden hearing loss directly associated with pregnancy or birth is a little known and rare occurrence. The temporary, unilateral, low-frequency sensorineural hearing loss in this case was reported after the birth of the patient\\'s first child, and again during the third trimester of her second pregnancy.
Systemic Steroid Application Caused Sudden Death of a Patient with Sudden Deafness
Directory of Open Access Journals (Sweden)
Eriko Ogino-Nishimura
2013-01-01
Full Text Available A 63-year-old man, who was diagnosed with sudden sensorineural hearing loss (SSHL, showed severe hypertension 10 hours after prednisolone administration. Subsequently, the patient suddenly died due to pulmonary edema. The autopsy indicated a pheochromocytoma in the right adrenal gland, and the cause of death was determined to be a pheochromocytoma crisis induced by systemic administration of prednisolone. Pheochromocytoma crisis is a life-threatening condition and can result from the use of corticosteroids. Physicians should consider the risk of a pheochromocytoma crisis due to systemic corticosteroids in the treatment of patients with sudden sensorineural hearing loss.
On a fine structure of a primary impulse of a magnetic storm sudden commencement
International Nuclear Information System (INIS)
Parkhomov, V.A.
1985-01-01
A fine structure of a primary reverse impulse of a sudden commencement (SSC*) of a magnetic storm is analyzed. 200 cases of SSC* recorded in 1965-79 have been chosen for the investigation. It is shown that the preliminary impulse of the sudden copmencement of magnetic storms has a fine structure in the form of the train of damped oscillations in Pc2-3 range of < or approximately 2 min durations. The excitation of oscillations is related with the propagation of the fast magnetoacoustic wave which is generated during interaction of the interplanetary shock wave with the earth magnetosphere
International Nuclear Information System (INIS)
Chan, C.K.; Hoffman, D.K.; Evans, J.W.
1985-01-01
Local, i.e., multiplicative, operators satisfy well-known linear factorization relations wherein matrix elements (between states associated with a complete set of wave functions) can be obtained as a linear combination of those out of the ground state (the input data). Analytic derivation of factorization relations for general state input data results in singular integral expressions for the coefficients, which can, however, be regularized using consistency conditions between matrix elements out of a single (nonground) state. Similar results hold for suitable ''symmetry class'' averaged matrix elements where the symmetry class projection operators are ''complete.'' In several cases where the wave functions or projection operators incorporate orthogonal polynomial dependence, we show that the ground state factorization relations have a simplified structure allowing an alternative derivation of the general factorization relations via an infinite matrix inversion procedure. This form is shown to have some advantages over previous versions. In addition, this matrix inversion procedure obtains all consistency conditions (which is not always the case from regularization of singular integrals)
Sudden rotation reactive scattering: Theory and application to 3-D H+H2
International Nuclear Information System (INIS)
Bowman, J.M.; Lee, K.T.
1980-01-01
An approximate quantum mechanical theory of reactive scattering is presented and applied to the H+H 2 reaction in three dimensions. Centrifugal sudden and rotational sudden approximations are made in each arrangement channel, however, vibrational states are treated in a fully coupled manner. Matching of arrangement channel wave functions is done where the arrangement channel centrifugal potentials are equal. This matching is particularly appropriate for collinearly favored reactions. Integral and differential cross sections are calculated for the H+H 2 reaction for H 2 in the ground and first excited vibrational states. These calculations employ the Porter--Karplus potential energy surface mainly to allow for comparisons with previous accurate and approximate quantal and quasiclassical calculations
International Nuclear Information System (INIS)
Ginsburg, C.A.
1980-01-01
In many problems, a desired property A of a function f(x) is determined by the behaviour of f(x) approximately equal to g(x,A) as x→xsup(*). In this letter, a method for resuming the power series in x of f(x) and approximating A (modulated Pade approximant) is presented. This new approximant is an extension of a resumation method for f(x) in terms of rational functions. (author)
Sudden Cardiac Death During Sports Activities in the General Population.
Narayanan, Kumar; Bougouin, Wulfran; Sharifzadehgan, Ardalan; Waldmann, Victor; Karam, Nicole; Marijon, Eloi; Jouven, Xavier
2017-12-01
Regular exercise reduces cardiovascular and overall mortality. Participation in sports is an important determinant of cardiovascular health and fitness. Regular sports activity is associated with a smaller risk of sudden cardiac death (SCD). However, there is a small risk of sports-related SCD. Sports-related SCD accounts for approximately 5% of total SCD. SCD among athletes comprises only a fraction of all sports-related SCD. Sport-related SCD has a male predominance and an average age of affliction of 45 to 50 years. Survival is better than for other SCD. This review summarizes links between sports and SCD and discusses current knowledge and controversies. Copyright © 2017 Elsevier Inc. All rights reserved.
Sudden Sensorineural Hearing Loss; Prognostic Factors
Directory of Open Access Journals (Sweden)
Arjun Dass
2015-09-01
Full Text Available Introduction: Sudden sensorineural hearing loss (SSNHL is a frightening and frustrating symptom for the patient as well as the physician. Prognosis is affected by multiple factors including duration of hearing loss, presence of associated vertigo and tinnitus, and co-morbidities such as hypertension and diabetes. Materials and Methods: Forty subjects presenting to our department with features of sudden hearing loss were included in the study. Detailed otological history and examination, serial audiometric findings and course of disease were studied. Results: Subjects presenting late (in older age, having associated vertigo, hypertension and diabetes had a significantly lower rate of recovery. Conclusion: Only 60–65% of patients experiencing SSNHL recover within a period of 1 month; this rate is further affected by presence of multiple prognostic indicators.
Sudden viscous dissipation in compressing plasma turbulence
Davidovits, Seth; Fisch, Nathaniel
2015-11-01
Compression of a turbulent plasma or fluid can cause amplification of the turbulent kinetic energy, if the compression is fast compared to the turnover and viscous dissipation times of the turbulent eddies. The consideration of compressing turbulent flows in inviscid fluids has been motivated by the suggestion that amplification of turbulent kinetic energy occurred on experiments at the Weizmann Institute of Science Z-Pinch. We demonstrate a sudden viscous dissipation mechanism whereby this amplified turbulent kinetic energy is rapidly converted into thermal energy, which further increases the temperature, feeding back to further enhance the dissipation. Application of this mechanism in compression experiments may be advantageous, if the plasma can be kept comparatively cold during much of the compression, reducing radiation and conduction losses, until the plasma suddenly becomes hot. This work was supported by DOE through contract 67350-9960 (Prime # DOE DE-NA0001836) and by the DTRA.
Classification of sudden and arrhythmic death
DEFF Research Database (Denmark)
Torp-Pedersen, C; Køber, L; Elming, H
1997-01-01
was nearly abolished by the implantable defibrillator, indicating that arrhythmic death by this classification is meaningful, at least in the population studied. For future investigations, a call is made for committees to present data in a way that allows the reader to examine the quality of the data used......Since all death is (eventually) sudden and associated with cardiac arrhythmias, the concept of sudden death is only meaningful if it is unexpected, while arrhythmic death is only meaningful if life could have continued had the arrhythmia been prevented or treated. Current classifications of death...... or autopsy) are available in only a few percent of cases. A main problem in using classifications is the lack of validation data. This situation has, with the MADIT trial, changed in the case of the Thaler and Hinkle classification of arrhythmic death. The MADIT trial demonstrated that arrhythmic death...
Sparse approximation with bases
2015-01-01
This book systematically presents recent fundamental results on greedy approximation with respect to bases. Motivated by numerous applications, the last decade has seen great successes in studying nonlinear sparse approximation. Recent findings have established that greedy-type algorithms are suitable methods of nonlinear approximation in both sparse approximation with respect to bases and sparse approximation with respect to redundant systems. These insights, combined with some previous fundamental results, form the basis for constructing the theory of greedy approximation. Taking into account the theoretical and practical demand for this kind of theory, the book systematically elaborates a theoretical framework for greedy approximation and its applications. The book addresses the needs of researchers working in numerical mathematics, harmonic analysis, and functional analysis. It quickly takes the reader from classical results to the latest frontier, but is written at the level of a graduate course and do...
Cerebral Paragonimiasis Presenting with Sudden Death.
Amaro, Deirdre E; Cowell, Annie; Tuohy, Marion J; Procop, Gary W; Morhaime, Jacquelyn; Reed, Sharon L
2016-12-07
A 58-year-old Korean-born woman with a history of seizures and psychiatric issues was found dead at home. Autopsy was notable for large, calcified nodules that had nearly replaced her right temporal lobe. Histologic examination revealed the presence of Paragonimus eggs. This case demonstrates a rare manifestation of an aberrantly migrated lung fluke that resulted in epilepsy and sudden death years after the initial infection. © The American Society of Tropical Medicine and Hygiene.
Sudden hearing loss after an explosion
Directory of Open Access Journals (Sweden)
Irfan Mohamad
2013-12-01
Full Text Available An 18-year-old man presented with a sudden onset of bilateral hearing loss after a home-made firework exploded near the right side of his scalp. The hearing loss was associated with tinnitus. Examination revealed an area of skin loss on the right pinna. There was mild bleeding from the right pinna and scalp at the mastoid region, which spontaneously resolved. An otoscopic examination is shown in Figure 1.
Sudden behavior change in a cat.
Gelberg, H B
2013-11-01
A 5-year-old, spayed female, domestic short-haired cat had a 10-day history of sudden behavioral changes followed by seizures. Blood parameters were in the reference ranges, and radiographs failed to detect a mass lesion in the brain. Euthanasia was followed by rabies testing, which was negative. Gross lesions were absent. Histologic changes were present only in the brain and consisted of foci of hippocampal pyramidal cell loss, mild gliosis, pallor of the associated neuropil, and neovascularization.
Imaging spectrum of sudden athlete cardiac death
Energy Technology Data Exchange (ETDEWEB)
Arrigan, M.T., E-mail: martinarrigan@gmail.co [Department of Radiology, Adelaide and Meath Hospital incorporating the National Children' s Hospital, Dublin (Ireland); Killeen, R.P. [Department of Radiology, Adelaide and Meath Hospital incorporating the National Children' s Hospital, Dublin (Ireland); Dodd, J.D. [Department of Radiology, St Vincent' s University Hospital, Dublin (Ireland); Torreggiani, W.C. [Department of Radiology, Adelaide and Meath Hospital incorporating the National Children' s Hospital, Dublin (Ireland)
2011-03-15
Sudden athlete death (SAD) is a widely publicized and increasingly reported phenomenon. For many, the athlete population epitomize human physical endeavour and achievement and their unexpected death comes with a significant emotional impact on the public. Sudden deaths within this group are often without prior warning. Preceding symptoms of exertional syncope and chest pain do, however, occur and warrant investigation. Similarly, a positive family history of sudden death in a young person or a known family history of a condition associated with SAD necessitates further tests. Screening programmes aimed at detecting those at risk individuals also exist with the aim of reducing fatalities. In this paper we review the topic of SAD and discuss the epidemiology, aetiology, and clinical presentations. We then proceed to discuss each underlying cause, in turn discussing the pathophysiology of each condition. This is followed by a discussion of useful imaging methods with an emphasis on cardiac magnetic resonance and cardiac computed tomography and how these address the various issues raised by the pathophysiology of each entity. We conclude by proposing imaging algorithms for the investigation of patients considered at risk for these conditions and discuss the various issues raised in screening.
Primordial spectra from sudden turning trajectory
Noumi, Toshifumi; Yamaguchi, Masahide
2013-12-01
Effects of heavy fields on primordial spectra of curvature perturbations are discussed in inflationary models with a sudden turning trajectory. When heavy fields are excited after the sudden turn and oscillate around the bottom of the potential, the following two effects are generically induced: deformation of the inflationary background spacetime and conversion interactions between adiabatic and isocurvature perturbations, both of which can affect the primordial density perturbations. In this paper, we calculate primordial spectra in inflationary models with sudden turning potentials taking into account both of the two effects appropriately. We find that there are some non-trivial correlations between the two effects in the power spectrum and, as a consequence, the primordial scalar power spectrum has a peak around the scale exiting the horizon at the turn. Though both effects can induce parametric resonance amplifications, they are shown to be canceled out for the case with the canonical kinetic terms. The peak feature and the scale dependence of bispectra are also discussed.
Magnetic resonance imaging in sudden deafness
International Nuclear Information System (INIS)
Ramos, Hugo Valter Lisboa; Barros, Flavia Alencar; Penido, Norma de Oliveira; Souza, Ana Claudia Valerio de; Yamaoka, Wellington Yugo; Yamashita, Helio
2005-01-01
The etiology of sudden deafness can remain undetermined despite extensive investigation. This study addresses the value of magnetic resonance imaging in the analysis of sudden deafness patients.Study Design: transversal cohort.Material And Method: In a prospective study, 49 patients attended at otolaryngology emergency room of Federal University of Sao Paulo - Escola Paulista de Medicina, from April 2001 to May 2003, were submitted to magnetic resonance imaging.Results: Magnetic Resonance abnormalities were seen in 23 (46.9%) patients and revealed two tumors suggestive of meningioma, three vestibular schwannomas, thirteen microangiopathic changes of the brain and five (21.7%) pathological conditions of the labyrinth.Conclusion: Sudden deafness should be approached as a symptom common to different diseases. The presence of cerebellopontine angle tumors in 10.2% of our cases, among other treatable causes, justifies the recommendation of gadolinium-enhanced magnetic resonance use, not only to study the auditory peripheral pathway, but to study the whole auditory pathway including the brain. (author)
Imaging spectrum of sudden athlete cardiac death.
LENUS (Irish Health Repository)
Arrigan, M T
2012-02-01
Sudden athlete death (SAD) is a widely publicized and increasingly reported phenomenon. For many, the athlete population epitomize human physical endeavour and achievement and their unexpected death comes with a significant emotional impact on the public. Sudden deaths within this group are often without prior warning. Preceding symptoms of exertional syncope and chest pain do, however, occur and warrant investigation. Similarly, a positive family history of sudden death in a young person or a known family history of a condition associated with SAD necessitates further tests. Screening programmes aimed at detecting those at risk individuals also exist with the aim of reducing fatalities. In this paper we review the topic of SAD and discuss the epidemiology, aetiology, and clinical presentations. We then proceed to discuss each underlying cause, in turn discussing the pathophysiology of each condition. This is followed by a discussion of useful imaging methods with an emphasis on cardiac magnetic resonance and cardiac computed tomography and how these address the various issues raised by the pathophysiology of each entity. We conclude by proposing imaging algorithms for the investigation of patients considered at risk for these conditions and discuss the various issues raised in screening.
Imaging spectrum of sudden athlete cardiac death
International Nuclear Information System (INIS)
Arrigan, M.T.; Killeen, R.P.; Dodd, J.D.; Torreggiani, W.C.
2011-01-01
Sudden athlete death (SAD) is a widely publicized and increasingly reported phenomenon. For many, the athlete population epitomize human physical endeavour and achievement and their unexpected death comes with a significant emotional impact on the public. Sudden deaths within this group are often without prior warning. Preceding symptoms of exertional syncope and chest pain do, however, occur and warrant investigation. Similarly, a positive family history of sudden death in a young person or a known family history of a condition associated with SAD necessitates further tests. Screening programmes aimed at detecting those at risk individuals also exist with the aim of reducing fatalities. In this paper we review the topic of SAD and discuss the epidemiology, aetiology, and clinical presentations. We then proceed to discuss each underlying cause, in turn discussing the pathophysiology of each condition. This is followed by a discussion of useful imaging methods with an emphasis on cardiac magnetic resonance and cardiac computed tomography and how these address the various issues raised by the pathophysiology of each entity. We conclude by proposing imaging algorithms for the investigation of patients considered at risk for these conditions and discuss the various issues raised in screening.
Approximate symmetries of Hamiltonians
Chubb, Christopher T.; Flammia, Steven T.
2017-08-01
We explore the relationship between approximate symmetries of a gapped Hamiltonian and the structure of its ground space. We start by considering approximate symmetry operators, defined as unitary operators whose commutators with the Hamiltonian have norms that are sufficiently small. We show that when approximate symmetry operators can be restricted to the ground space while approximately preserving certain mutual commutation relations. We generalize the Stone-von Neumann theorem to matrices that approximately satisfy the canonical (Heisenberg-Weyl-type) commutation relations and use this to show that approximate symmetry operators can certify the degeneracy of the ground space even though they only approximately form a group. Importantly, the notions of "approximate" and "small" are all independent of the dimension of the ambient Hilbert space and depend only on the degeneracy in the ground space. Our analysis additionally holds for any gapped band of sufficiently small width in the excited spectrum of the Hamiltonian, and we discuss applications of these ideas to topological quantum phases of matter and topological quantum error correcting codes. Finally, in our analysis, we also provide an exponential improvement upon bounds concerning the existence of shared approximate eigenvectors of approximately commuting operators under an added normality constraint, which may be of independent interest.
Approximating distributions from moments
Pawula, R. F.
1987-11-01
A method based upon Pearson-type approximations from statistics is developed for approximating a symmetric probability density function from its moments. The extended Fokker-Planck equation for non-Markov processes is shown to be the underlying foundation for the approximations. The approximation is shown to be exact for the beta probability density function. The applicability of the general method is illustrated by numerous pithy examples from linear and nonlinear filtering of both Markov and non-Markov dichotomous noise. New approximations are given for the probability density function in two cases in which exact solutions are unavailable, those of (i) the filter-limiter-filter problem and (ii) second-order Butterworth filtering of the random telegraph signal. The approximate results are compared with previously published Monte Carlo simulations in these two cases.
CONTRIBUTIONS TO RATIONAL APPROXIMATION,
Some of the key results of linear Chebyshev approximation theory are extended to generalized rational functions. Prominent among these is Haar’s...linear theorem which yields necessary and sufficient conditions for uniqueness. Some new results in the classic field of rational function Chebyshev...Furthermore a Weierstrass type theorem is proven for rational Chebyshev approximation. A characterization theorem for rational trigonometric Chebyshev approximation in terms of sign alternation is developed. (Author)
Approximation techniques for engineers
Komzsik, Louis
2006-01-01
Presenting numerous examples, algorithms, and industrial applications, Approximation Techniques for Engineers is your complete guide to the major techniques used in modern engineering practice. Whether you need approximations for discrete data of continuous functions, or you''re looking for approximate solutions to engineering problems, everything you need is nestled between the covers of this book. Now you can benefit from Louis Komzsik''s years of industrial experience to gain a working knowledge of a vast array of approximation techniques through this complete and self-contained resource.
Expectation Consistent Approximate Inference
DEFF Research Database (Denmark)
Opper, Manfred; Winther, Ole
2005-01-01
We propose a novel framework for approximations to intractable probabilistic models which is based on a free energy formulation. The approximation can be understood from replacing an average over the original intractable distribution with a tractable one. It requires two tractable probability dis...
Ordered cones and approximation
Keimel, Klaus
1992-01-01
This book presents a unified approach to Korovkin-type approximation theorems. It includes classical material on the approximation of real-valuedfunctions as well as recent and new results on set-valued functions and stochastic processes, and on weighted approximation. The results are notonly of qualitative nature, but include quantitative bounds on the order of approximation. The book is addressed to researchers in functional analysis and approximation theory as well as to those that want to applythese methods in other fields. It is largely self- contained, but the readershould have a solid background in abstract functional analysis. The unified approach is based on a new notion of locally convex ordered cones that are not embeddable in vector spaces but allow Hahn-Banach type separation and extension theorems. This concept seems to be of independent interest.
Symptoms Before Sudden Arrhythmic Death Syndrome
DEFF Research Database (Denmark)
Glinge, Charlotte; Jabbari, Reza; Risgaard, Bjarke
2015-01-01
INTRODUCTION: No studies in an unselected and nationwide setting have characterized the symptoms and medical history of patients with sudden arrhythmic death syndrome (SADS). The aim of this study was to identify and describe the symptoms and medical history of patients before the presentation......%), palpitations (n = 2, 1%), presyncope/syncope (n = 23, 17%), and aborted SCD (n = 2, 1%). In addition, seizures (n = 25, 18%) were prevalent. In 61 (45%) SADS cases, no previous medical history were recorded. CONCLUSION: In this unselected, nationwide study of 136 young SADS patients, 35% had experienced...
Approximate and renormgroup symmetries
Energy Technology Data Exchange (ETDEWEB)
Ibragimov, Nail H. [Blekinge Institute of Technology, Karlskrona (Sweden). Dept. of Mathematics Science; Kovalev, Vladimir F. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Mathematical Modeling
2009-07-01
''Approximate and Renormgroup Symmetries'' deals with approximate transformation groups, symmetries of integro-differential equations and renormgroup symmetries. It includes a concise and self-contained introduction to basic concepts and methods of Lie group analysis, and provides an easy-to-follow introduction to the theory of approximate transformation groups and symmetries of integro-differential equations. The book is designed for specialists in nonlinear physics - mathematicians and non-mathematicians - interested in methods of applied group analysis for investigating nonlinear problems in physical science and engineering. (orig.)
Approximate and renormgroup symmetries
International Nuclear Information System (INIS)
Ibragimov, Nail H.; Kovalev, Vladimir F.
2009-01-01
''Approximate and Renormgroup Symmetries'' deals with approximate transformation groups, symmetries of integro-differential equations and renormgroup symmetries. It includes a concise and self-contained introduction to basic concepts and methods of Lie group analysis, and provides an easy-to-follow introduction to the theory of approximate transformation groups and symmetries of integro-differential equations. The book is designed for specialists in nonlinear physics - mathematicians and non-mathematicians - interested in methods of applied group analysis for investigating nonlinear problems in physical science and engineering. (orig.)
Approximations of Fuzzy Systems
Directory of Open Access Journals (Sweden)
Vinai K. Singh
2013-03-01
Full Text Available A fuzzy system can uniformly approximate any real continuous function on a compact domain to any degree of accuracy. Such results can be viewed as an existence of optimal fuzzy systems. Li-Xin Wang discussed a similar problem using Gaussian membership function and Stone-Weierstrass Theorem. He established that fuzzy systems, with product inference, centroid defuzzification and Gaussian functions are capable of approximating any real continuous function on a compact set to arbitrary accuracy. In this paper we study a similar approximation problem by using exponential membership functions
Potvin, Guy
2015-10-01
We examine how the Rytov approximation describing log-amplitude and phase fluctuations of a wave propagating through weak uniform turbulence can be generalized to the case of turbulence with a large-scale nonuniform component. We show how the large-scale refractive index field creates Fermat rays using the path integral formulation for paraxial propagation. We then show how the second-order derivatives of the Fermat ray action affect the Rytov approximation, and we discuss how a numerical algorithm would model the general Rytov approximation.
Infinite-order-sudden method for light--heavy--light reactions: Application to D+HCl→DCl+H
International Nuclear Information System (INIS)
Clary, D.C.; Drolshagen, G.
1982-01-01
An infinite-order-sudden (IOS) theory for light-heavy-light reactions is applied to the D+HCl(v = 0, j)→DCl(v'< or =1, j')+H reaction. The results are compared with those obtained using a more accurate quantum-dynamical technique, the ESA--CSA method, in which the energy sudden approximation is used for the entrance channel, while the centrifugal sudden approximation is employed for the exit channel. The computations have been performed using LEPS and DIM potential energy surfaces. We obtain good agreement between the IOS and ESA--CSA results, not only for averaged quantities such as rate coefficients, but also for detailed vibrational-rotational reactive cross sections
Sudden improvement of insulin sensitivity related to an endodontic treatment.
Schulze, A; Schönauer, M; Busse, M
2007-12-01
Inflammation contributes to the pathogenesis of diabetes. A reciprocal relationship exists between diabetes and chronic periodontitis. This report describes the effects of an acute focal dental inflammation and subsequent endodontic treatment on the required insulin dosage of a 70-year-old man who had moderately controlled diabetes. Following an exacerbation of a combined endodontic-periodontic (endo-perio) lesion of tooth #3, the patient noticed a sudden increase in his insulin demand. After 3 weeks, the required dosage was approximately 100% greater. In association with hyperglycemic incidents, he reported a prickling sensation in this tooth. The radiograph showed circular bone loss around the tooth. Just 1 day after the root-canal preparation, the insulin need decreased to approximately 50% of that required prior to treatment. Subsequently, an incision and systemic antibiotics were necessary because of the formation of a periodontal abscess. The insulin demand remained low despite this complication. Forty days after endodontic treatment, the insulin dosage was at a level comparable to that taken 4 weeks before the root-canal preparation. This clinical case revealed a highly relevant correlation between insulin resistance and a local dental inflammation. To avoid an increase in insulin resistance, it seems important to attend to radically non-vital teeth as well as any other dental inflammation in diabetic patients.
Geometric approximation algorithms
Har-Peled, Sariel
2011-01-01
Exact algorithms for dealing with geometric objects are complicated, hard to implement in practice, and slow. Over the last 20 years a theory of geometric approximation algorithms has emerged. These algorithms tend to be simple, fast, and more robust than their exact counterparts. This book is the first to cover geometric approximation algorithms in detail. In addition, more traditional computational geometry techniques that are widely used in developing such algorithms, like sampling, linear programming, etc., are also surveyed. Other topics covered include approximate nearest-neighbor search, shape approximation, coresets, dimension reduction, and embeddings. The topics covered are relatively independent and are supplemented by exercises. Close to 200 color figures are included in the text to illustrate proofs and ideas.
International Nuclear Information System (INIS)
Knobloch, A.F.
1980-01-01
A simplified cost approximation for INTOR parameter sets in a narrow parameter range is shown. Plausible constraints permit the evaluation of the consequences of parameter variations on overall cost. (orig.) [de
Gautschi, Walter; Rassias, Themistocles M
2011-01-01
Approximation theory and numerical analysis are central to the creation of accurate computer simulations and mathematical models. Research in these areas can influence the computational techniques used in a variety of mathematical and computational sciences. This collection of contributed chapters, dedicated to renowned mathematician Gradimir V. Milovanovia, represent the recent work of experts in the fields of approximation theory and numerical analysis. These invited contributions describe new trends in these important areas of research including theoretic developments, new computational alg
Otolaryngological aspects of sudden infant death syndrome.
Marom, Tal; Cinamon, Udi; Castellanos, Paul F; Cohen, Marta C
2012-03-01
Sudden infant death syndrome (SIDS) is characterized by the sudden death of an apparently otherwise healthy infant, typically during sleep, and with no obvious case after a thorough post-mortem and scene death examination. To address the problem from the otolaryngologist's perspective, describe relevant pathologies, discuss controversies and suggest preventive measures in high-risk populations. A MEDLINE search and hand search were conducted to identify reports published between 1969 and 2011 in the English language on the pathophysiology of SIDS related to the head and neck organs. Search terms included SIDS (MeSH term), SIDS and pathophysiology (text words), and SIDS and autopsy (text words). A growing number of reports suggested head and neck organs involvement in SIDS autopsies. Laryngeal, oropharyngeal, maxillofacial, otologic, cervical vascular abnormalities and infectious etiologies, were recognized and discussed. Otolaryngologists should be aware of relevant pathologies, as some are treatable, if identified early enough in infancy. A proactive risk-management approach is warranted in infants presenting with certain abnormalities reviewed here. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Febrile seizures prior to sudden cardiac death
DEFF Research Database (Denmark)
Stampe, Niels Kjær; Glinge, Charlotte; Jabbari, Reza
2018-01-01
Aims: Febrile seizure (FS) is a common disorder affecting 2-5% of children up to 5 years of age. The aim of this study was to determine whether FS in early childhood are over-represented in young adults dying from sudden cardiac death (SCD). Methods and results: We included all deaths (n = 4595...... with FS was sudden arrhythmic death syndrome (5/8; 62.5%). Conclusion: In conclusion, this study demonstrates a significantly two-fold increase in the frequency of FS prior to death in young SCD cases compared with the two control groups, suggesting that FS could potentially contribute in a risk......) nationwide and through review of all death certificates, we identified 245 SCD in Danes aged 1-30 years in 2000-09. Through the usage of nationwide registries, we identified all persons admitted with first FS among SCD cases (14/245; 5.7%) and in the corresponding living Danish population (71 027/2 369 785...
Initial conditions and entanglement sudden death
International Nuclear Information System (INIS)
Qian, Xiao-Feng; Eberly, J.H.
2012-01-01
We report results bearing on the behavior of non-local decoherence and its potential for being managed or even controlled. The decoherence process known as entanglement sudden death (ESD) can drive prepared entanglement to zero at the same time that local coherences and fidelity remain non-zero. For a generic ESD-susceptible Bell superposition state, we provide rules restricting the occurrence and timing of ESD, amounting to management tools over a continuous variation of initial conditions. These depend on only three parameters: initial purity, entanglement and excitation. Knowledge or control of initial phases is not needed. -- Highlights: ► We study the possibility of managing disentanglement through initial conditions. ► The initial parameters are the amount of entanglement, excitation, and purity. ► Entanglement sudden death (ESD) free and ESD susceptible phases are identified. ► ESD onset time is also presented in the ESD susceptible phase. ► Our results may guide experiments to prepare ESD free or delayed ESD states.
Approximate kernel competitive learning.
Wu, Jian-Sheng; Zheng, Wei-Shi; Lai, Jian-Huang
2015-03-01
Kernel competitive learning has been successfully used to achieve robust clustering. However, kernel competitive learning (KCL) is not scalable for large scale data processing, because (1) it has to calculate and store the full kernel matrix that is too large to be calculated and kept in the memory and (2) it cannot be computed in parallel. In this paper we develop a framework of approximate kernel competitive learning for processing large scale dataset. The proposed framework consists of two parts. First, it derives an approximate kernel competitive learning (AKCL), which learns kernel competitive learning in a subspace via sampling. We provide solid theoretical analysis on why the proposed approximation modelling would work for kernel competitive learning, and furthermore, we show that the computational complexity of AKCL is largely reduced. Second, we propose a pseudo-parallelled approximate kernel competitive learning (PAKCL) based on a set-based kernel competitive learning strategy, which overcomes the obstacle of using parallel programming in kernel competitive learning and significantly accelerates the approximate kernel competitive learning for large scale clustering. The empirical evaluation on publicly available datasets shows that the proposed AKCL and PAKCL can perform comparably as KCL, with a large reduction on computational cost. Also, the proposed methods achieve more effective clustering performance in terms of clustering precision against related approximate clustering approaches. Copyright © 2014 Elsevier Ltd. All rights reserved.
Krexi, Dimitra; Sheppard, Mary N
2017-05-01
This study aims to determine the causes of sudden cardiac death during pregnancy and in the postpartum period and patients' characteristics. There are few studies in the literature. Eighty cases of sudden unexpected death due to cardiac causes in relation to pregnancy and postpartum period in a database of 4678 patients were found and examined macroscopically and microscopically. The mean age was 30±7 years with a range from 16 to 43 years. About 30% were 35 years old or older; 50% of deaths occurred during pregnancy and 50% during the postpartum period. About 59.18% were obese or overweight where body mass index data were available. The leading causes of death were sudden arrhythmic death syndrome (SADS) (53.75%) and cardiomyopathies (13.80%). Other causes include dissection of aorta or its branches (8.75%), congenital heart disease (2.50%) and valvular disease (3.75%). This study highlights sudden cardiac death in pregnancy or in the postpartum period, which is mainly due to SADS with underlying channelopathies and cardiomyopathy. We wish to raise awareness of these frequently under-recognised entities in maternal deaths and the need of cardiological screening of the family as a result of the diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.
Residual entanglement and sudden death: A direct connection
International Nuclear Information System (INIS)
Oliveira, J.G.G. de; Peixoto de Faria, J.G.; Nemes, M.C.
2011-01-01
We explore the results of [V. Coffman, et al., Phys. Rev. A 61 (2000) 052306] derived for general tripartite states in a dynamical context. We study a class of physically motivated tripartite systems. We show that whenever entanglement sudden death occurs in one of the partitions residual entanglement will appear. For fourpartite systems however, the appearance of residual entanglement is not conditioned by sudden death of entanglement. We can only say that if sudden death of entanglement occurs in some partition there will certainly be residual entanglement. -- Highlights: ► For tripartite systems we show there exists residual entanglement if sudden death occurs. ► For fourpartite systems, the residual entanglement is not conditioned by sudden death. ► If sudden death of entanglement occurs there will certainly be residual entanglement.
Cardiac Channelopathies and Sudden Death: Recent Clinical and Genetic Advances
Fernández Falgueras, Anna; Sarquella Brugada, Georgia; Brugada Terradellas, Josep; Brugada, Ramon; Campuzano Larrea, Oscar
2017-01-01
Sudden cardiac death poses a unique challenge to clinicians because it may be the only symptom of an inherited heart condition. Indeed, inherited heart diseases can cause sudden cardiac death in older and younger individuals. Two groups of familial diseases are responsible for sudden cardiac death: cardiomyopathies (mainly hypertrophic cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic cardiomyopathy) and channelopathies (mainly long QT syndrome, Brugada syndrome, short QT syndrome, a...
Good news is bad news: Leverage cycles and sudden stops
Akinci, Ozge; Chahrour, Ryan
2015-01-01
We show that a model with imperfectly forecastable changes in future productivity and an occasionally binding collateral constraint can match a set of stylized facts about “sudden stop” events. “Good” news about future productivity raises leverage during times of expansion, increasing the probability that the constraint binds, and a sudden stop occurs, in future periods. The economy exhibits a boom period in the run-up to the sudden stop, with output, consumption, and investment all above tre...
On Covering Approximation Subspaces
Directory of Open Access Journals (Sweden)
Xun Ge
2009-06-01
Full Text Available Let (U';C' be a subspace of a covering approximation space (U;C and X⊂U'. In this paper, we show that and B'(X⊂B(X∩U'. Also, iff (U;C has Property Multiplication. Furthermore, some connections between outer (resp. inner definable subsets in (U;C and outer (resp. inner definable subsets in (U';C' are established. These results answer a question on covering approximation subspace posed by J. Li, and are helpful to obtain further applications of Pawlak rough set theory in pattern recognition and artificial intelligence.
Sudden cardiac death in adults: causes, incidence and interventions.
Walker, Wendy Marina
Many nurses will be familiar with the unexpected death of an adult patient following a sudden, life-threatening cardiac event. It is a situation that demands sensitive nursing care and skilled interventions to provide a foundation for recovery and promote healthy bereavement. This article examines the causes and incidence of sudden cardiac death in adults. Possible reactions of those who are suddenly bereaved are described and immediate care interventions aimed at dealing with the grief process are discussed. The article concludes by identifying ways in which the incidence of sudden cardiac death may be reduced.
Distillability Sudden Birth of Entanglement for Qutrit-Qutrit Systems
International Nuclear Information System (INIS)
Huang Jiang; Ali Mazhar
2014-01-01
We report the sudden appearance of distillability between two statistically independent reservoirs modelled as qutrit-qutrit systems. This feature of bipartite quantum systems is different from the previously observed phenomenon of entanglement sudden birth. It is found that the states of reservoirs first become bound entangled, thus exhibiting entanglement sudden birth, consequently followed by the sudden birth of distillability, and it is shown that whenever distillability is lost abruptly from principal system, it also necessarily appears abruptly among reservoirs' degrees of freedom. This surprising observation reflects yet another peculiarity of dynamical aspects of quantum entanglement
Sudden cardiac death in the young
Ackerman, Michael; Atkins, Dianne L; Triedman, John K
2016-01-01
Although the occurrence of sudden cardiac death (SCD) in a young person is a rare event, it is traumatic and often widely publicized. In recent years, SCD in this population has been increasingly seen as a public health and safety issue. This review presents current knowledge relevant to the epidemiology of SCD and to strategies for prevention, resuscitation and identification of those at greatest risk. Areas of active research and controversy include the development of best practices in screening, risk stratification approaches and post-mortem evaluation, and identification of modifiable barriers to providing better outcomes after resuscitation of young SCD victims. Institution of a national registry of SCD in the young will provide data that will help to answer these questions. PMID:26951821
On Convex Quadratic Approximation
den Hertog, D.; de Klerk, E.; Roos, J.
2000-01-01
In this paper we prove the counterintuitive result that the quadratic least squares approximation of a multivariate convex function in a finite set of points is not necessarily convex, even though it is convex for a univariate convex function. This result has many consequences both for the field of
Prestack wavefield approximations
Alkhalifah, Tariq
2013-01-01
The double-square-root (DSR) relation offers a platform to perform prestack imaging using an extended single wavefield that honors the geometrical configuration between sources, receivers, and the image point, or in other words, prestack wavefields. Extrapolating such wavefields, nevertheless, suffers from limitations. Chief among them is the singularity associated with horizontally propagating waves. I have devised highly accurate approximations free of such singularities which are highly accurate. Specifically, I use Padé expansions with denominators given by a power series that is an order lower than that of the numerator, and thus, introduce a free variable to balance the series order and normalize the singularity. For the higher-order Padé approximation, the errors are negligible. Additional simplifications, like recasting the DSR formula as a function of scattering angle, allow for a singularity free form that is useful for constant-angle-gather imaging. A dynamic form of this DSR formula can be supported by kinematic evaluations of the scattering angle to provide efficient prestack wavefield construction. Applying a similar approximation to the dip angle yields an efficient 1D wave equation with the scattering and dip angles extracted from, for example, DSR ray tracing. Application to the complex Marmousi data set demonstrates that these approximations, although they may provide less than optimal results, allow for efficient and flexible implementations. © 2013 Society of Exploration Geophysicists.
DEFF Research Database (Denmark)
Madsen, Rasmus Elsborg
2005-01-01
The Dirichlet compound multinomial (DCM), which has recently been shown to be well suited for modeling for word burstiness in documents, is here investigated. A number of conceptual explanations that account for these recent results, are provided. An exponential family approximation of the DCM...
Approximation by Cylinder Surfaces
DEFF Research Database (Denmark)
Randrup, Thomas
1997-01-01
We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...
Prestack wavefield approximations
Alkhalifah, Tariq
2013-09-01
The double-square-root (DSR) relation offers a platform to perform prestack imaging using an extended single wavefield that honors the geometrical configuration between sources, receivers, and the image point, or in other words, prestack wavefields. Extrapolating such wavefields, nevertheless, suffers from limitations. Chief among them is the singularity associated with horizontally propagating waves. I have devised highly accurate approximations free of such singularities which are highly accurate. Specifically, I use Padé expansions with denominators given by a power series that is an order lower than that of the numerator, and thus, introduce a free variable to balance the series order and normalize the singularity. For the higher-order Padé approximation, the errors are negligible. Additional simplifications, like recasting the DSR formula as a function of scattering angle, allow for a singularity free form that is useful for constant-angle-gather imaging. A dynamic form of this DSR formula can be supported by kinematic evaluations of the scattering angle to provide efficient prestack wavefield construction. Applying a similar approximation to the dip angle yields an efficient 1D wave equation with the scattering and dip angles extracted from, for example, DSR ray tracing. Application to the complex Marmousi data set demonstrates that these approximations, although they may provide less than optimal results, allow for efficient and flexible implementations. © 2013 Society of Exploration Geophysicists.
Directory of Open Access Journals (Sweden)
Antje Krüger
2014-09-01
Full Text Available Background: Exposure-based treatment approaches are first-line interventions for patients suffering from posttraumatic stress disorder (PTSD. However, the dissemination of exposure-based treatments for PTSD is challenging, as a large proportion of clinicians report being concerned about symptoms worsening as a result of this type of intervention and are therefore reluctant to offer it to patients with PTSD. However, there is only little empirical evidence to date on the pattern of symptom worsening during exposure-based treatment for PTSD. Objective: The goal of the present study was to explore the frequency of sudden losses and sudden gains in the course of an exposure-based treatment programme for female patients suffering from PTSD related to childhood sexual abuse who also show severe comorbidity. In addition, the relationship between sudden changes and treatment outcome was examined. Methods: Female participants (N=74 were randomised to either a 12-week residential DBT-PTSD programme or a treatment-as-usual wait list. The pattern of symptom change was assessed via weekly assessments using the Posttraumatic Diagnostic Scale (PDS. Sudden changes were computed as suggested by the literature on sudden gains. Results: During treatment, only one participant (3% experienced a sudden loss, whereas 25% of participants experienced sudden gains. In the waiting condition, 8% of the participants experienced sudden losses and 5% experienced sudden gains during the same time period. No symptom worsening was observed in response to exposure sessions. However, sudden gains occurred during exposure and non-exposure treatment weeks. Patients with sudden gains showed better treatment outcome in the post-treatment and follow-up assessments. Conclusions: Exposure-based treatment did not lead to PTSD symptom worsening in the study sample. Results show that sudden gains occur frequently during PTSD treatment and have a prognostic value for treatment outcome.
International Nuclear Information System (INIS)
Chuan-Jia, Shan; Tao, Chen; Ji-Bing, Liu; Wei-Wen, Cheng; Tang-Kun, Liu; Yan-Xia, Huang; Hong, Li
2010-01-01
In this paper, we investigate the dynamical behaviour of entanglement in terms of concurrence in a bipartite system subjected to an external magnetic field under the action of dissipative environments in the extended Werner-like initial state. The interesting phenomenon of entanglement sudden death as well as sudden birth appears during the evolution process. We analyse in detail the effect of the purity of the initial entangled state of two qubits via Heisenberg XY interaction on the apparition time of entanglement sudden death and entanglement sudden birth. Furthermore, the conditions on the conversion of entanglement sudden death and entanglement sudden birth can be generalized when the initial entangled state is not pure. In particular, a critical purity of the initial mixed entangled state exists, above which entanglement sudden birth vanishes while entanglement sudden death appears. It is also noticed that stable entanglement, which is independent of different initial states of the qubits (pure or mixed state), occurs even in the presence of decoherence. These results arising from the combination of the extended Werner-like initial state and dissipative environments suggest an approach to control and enhance the entanglement even after purity induced sudden birth, death and revival. (general)
An improved saddlepoint approximation.
Gillespie, Colin S; Renshaw, Eric
2007-08-01
Given a set of third- or higher-order moments, not only is the saddlepoint approximation the only realistic 'family-free' technique available for constructing an associated probability distribution, but it is 'optimal' in the sense that it is based on the highly efficient numerical method of steepest descents. However, it suffers from the problem of not always yielding full support, and whilst [S. Wang, General saddlepoint approximations in the bootstrap, Prob. Stat. Lett. 27 (1992) 61.] neat scaling approach provides a solution to this hurdle, it leads to potentially inaccurate and aberrant results. We therefore propose several new ways of surmounting such difficulties, including: extending the inversion of the cumulant generating function to second-order; selecting an appropriate probability structure for higher-order cumulants (the standard moment closure procedure takes them to be zero); and, making subtle changes to the target cumulants and then optimising via the simplex algorithm.
Prestack traveltime approximations
Alkhalifah, Tariq Ali
2011-01-01
Most prestack traveltime relations we tend work with are based on homogeneous (or semi-homogenous, possibly effective) media approximations. This includes the multi-focusing or double square-root (DSR) and the common reflection stack (CRS) equations. Using the DSR equation, I analyze the associated eikonal form in the general source-receiver domain. Like its wave-equation counterpart, it suffers from a critical singularity for horizontally traveling waves. As a result, I derive expansion based solutions of this eikonal based on polynomial expansions in terms of the reflection and dip angles in a generally inhomogenous background medium. These approximate solutions are free of singularities and can be used to estimate travetimes for small to moderate offsets (or reflection angles) in a generally inhomogeneous medium. A Marmousi example demonstrates the usefulness of the approach. © 2011 Society of Exploration Geophysicists.
Topology, calculus and approximation
Komornik, Vilmos
2017-01-01
Presenting basic results of topology, calculus of several variables, and approximation theory which are rarely treated in a single volume, this textbook includes several beautiful, but almost forgotten, classical theorems of Descartes, Erdős, Fejér, Stieltjes, and Turán. The exposition style of Topology, Calculus and Approximation follows the Hungarian mathematical tradition of Paul Erdős and others. In the first part, the classical results of Alexandroff, Cantor, Hausdorff, Helly, Peano, Radon, Tietze and Urysohn illustrate the theories of metric, topological and normed spaces. Following this, the general framework of normed spaces and Carathéodory's definition of the derivative are shown to simplify the statement and proof of various theorems in calculus and ordinary differential equations. The third and final part is devoted to interpolation, orthogonal polynomials, numerical integration, asymptotic expansions and the numerical solution of algebraic and differential equations. Students of both pure an...
Approximate Bayesian recursive estimation
Czech Academy of Sciences Publication Activity Database
Kárný, Miroslav
2014-01-01
Roč. 285, č. 1 (2014), s. 100-111 ISSN 0020-0255 R&D Projects: GA ČR GA13-13502S Institutional support: RVO:67985556 Keywords : Approximate parameter estimation * Bayesian recursive estimation * Kullback–Leibler divergence * Forgetting Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 4.038, year: 2014 http://library.utia.cas.cz/separaty/2014/AS/karny-0425539.pdf
Approximating Preemptive Stochastic Scheduling
Megow Nicole; Vredeveld Tjark
2009-01-01
We present constant approximative policies for preemptive stochastic scheduling. We derive policies with a guaranteed performance ratio of 2 for scheduling jobs with release dates on identical parallel machines subject to minimizing the sum of weighted completion times. Our policies as well as their analysis apply also to the recently introduced more general model of stochastic online scheduling. The performance guarantee we give matches the best result known for the corresponding determinist...
Optimization and approximation
Pedregal, Pablo
2017-01-01
This book provides a basic, initial resource, introducing science and engineering students to the field of optimization. It covers three main areas: mathematical programming, calculus of variations and optimal control, highlighting the ideas and concepts and offering insights into the importance of optimality conditions in each area. It also systematically presents affordable approximation methods. Exercises at various levels have been included to support the learning process.
Antipsychotics and the risk of sudden cardiac death
Straus, S.M.J.M.; Bleumink, G.S.; Dieleman, J.P.; van der Lei, J.; 't Jong, G.W.; Kingma, J. Herre; Sturkenboom, M.C J M; Stricker, B.H C
2004-01-01
Background Antipsychotics have been associated with prolongation of the corrected QT interval and sudden cardiac death. Only a few epidemiological studies have investigated this association. We performed a case-control study to investigate the association between use of antipsychotics and sudden
Directory of Open Access Journals (Sweden)
Yasushi Mochizuki
2018-03-01
Full Text Available A 60-year-old male displayed sudden shrinkage of a left free rectus abdominis musculocutaneous flap, which had been grafted to his left maxilla 15 years previously. No post-reconstructive irradiation had been performed, and no late occlusion of the vascular anastomosis, local infection, recurrence of the maxillary cancer, or body weight loss was observed. However, the shrinkage amounted to approximately 50%. This is considerably more than previously reported cases of shrinkage of various free flaps, which ranged between 10% and 25%. The resultant depression was successfully augmented with a right free deep inferior epigastric artery perforator flap. The residual fat volume of the previously grafted shrunken flap was revealed to be compatible with that of the newly harvested contralateral perforator flap. Thus, the volume of the previously grafted flap may reflect the status of the intact contralateral donor site, although the mechanism of sudden flap shrinkage is unclear.
Mobile phone usage does not affect sudden sensorineural hearing loss.
Sagiv, D; Migirov, L; Madgar, O; Nakache, G; Wolf, M; Shapira, Y
2018-01-01
Recent studies found that mobile phone users had a significantly greater risk of having elevated thresholds in speech frequencies. This study investigated the correlation between the laterality of sudden sensorineural hearing loss, handedness and the preferred ear for mobile phone use. The study included all patients who presented with sudden sensorineural hearing loss to the Department of Otolaryngology - Head and Neck Surgery in our tertiary referral medical centre between 2014 and 2016. Patients were asked to indicate their dominant hand and preferred ear for mobile phone use. The study comprised 160 patients. No correlation was found between the dominant hand or preferred ear for mobile phone use and the side of sudden sensorineural hearing loss. There was no correlation between the side of the sudden sensorineural hearing loss (preferable or non-preferable for mobile phone use) and audiometric characteristics. No correlation was found between the laterality of ears used for mobile phone and sudden sensorineural hearing loss.
Structural imaging biomarkers of sudden unexpected death in epilepsy.
Wandschneider, Britta; Koepp, Matthias; Scott, Catherine; Micallef, Caroline; Balestrini, Simona; Sisodiya, Sanjay M; Thom, Maria; Harper, Ronald M; Sander, Josemir W; Vos, Sjoerd B; Duncan, John S; Lhatoo, Samden; Diehl, Beate
2015-10-01
Sudden unexpected death in epilepsy is a major cause of premature death in people with epilepsy. We aimed to assess whether structural changes potentially attributable to sudden death pathogenesis were present on magnetic resonance imaging in people who subsequently died of sudden unexpected death in epilepsy. In a retrospective, voxel-based analysis of T1 volume scans, we compared grey matter volumes in 12 cases of sudden unexpected death in epilepsy (two definite, 10 probable; eight males), acquired 2 years [median, interquartile range (IQR) 2.8] before death [median (IQR) age at scanning 33.5 (22) years], with 34 people at high risk [age 30.5 (12); 19 males], 19 at low risk [age 30 (7.5); 12 males] of sudden death, and 15 healthy controls [age 37 (16); seven males]. At-risk subjects were defined based on risk factors of sudden unexpected death in epilepsy identified in a recent combined risk factor analysis. We identified increased grey matter volume in the right anterior hippocampus/amygdala and parahippocampus in sudden death cases and people at high risk, when compared to those at low risk and controls. Compared to controls, posterior thalamic grey matter volume, an area mediating oxygen regulation, was reduced in cases of sudden unexpected death in epilepsy and subjects at high risk. The extent of reduction correlated with disease duration in all subjects with epilepsy. Increased amygdalo-hippocampal grey matter volume with right-sided changes is consistent with histo-pathological findings reported in sudden infant death syndrome. We speculate that the right-sided predominance reflects asymmetric central influences on autonomic outflow, contributing to cardiac arrhythmia. Pulvinar damage may impair hypoxia regulation. The imaging findings in sudden unexpected death in epilepsy and people at high risk may be useful as a biomarker for risk-stratification in future studies. The Author (2015). Published by Oxford University Press on behalf of the Guarantors of
Sudden Death Following Exercise; a Case Series Study
Directory of Open Access Journals (Sweden)
Fares Najari
2016-04-01
Full Text Available Introduction: Natural and unexpected death that happens within less than one hour of first symptom occurrence is called sudden death. Cardiovascular diseases are the main known reason of sudden death and more than 75% of sudden deaths in athletes are assigned to it. Here we reported the autopsy results of all cases with sudden death following exercise that were referred to forensic center of Tehran, Iran, from 2009 to 2014. Methods: In this cross sectional study all subjects who were registered to forensic medicine center of Tehran, Iran, from 2009 to 2014, as a case of sudden death following exercise were evaluated. Demographic data and medical history as well as autopsy and toxicology findings were retrospectively gathered using profiles of the deceased. Results were reported using descriptive analysis. Results: 14 cases were registered as sudden death following exercise in forensic medicine profiles during the study period. Exploring the files of the mentioned deceased, revealed five non-compatible cases in this regard. Finally, 9 eligible cases were enrolled (88.9% male. The mean age of the deceased was 28.66 ± 10.86 years (range: 7 – 40. Toxicological tests were available for 7 cases, one of which was positive for tramadol. Sudden death following football was reported most frequently (44.4%. Only 3 (33.3% cases had herald signs such as chest pain, syncope, or loss of consciousness. 1 case (11.11% had a positive history of sudden death in relatives. Conclusion: Although most sudden death victims are asymptomatic until the event, all those who suffer from symptoms such as chest pain, shortness of breath, dizziness, fatigue and irregular heart rate during physical activities, should be screened regarding common probable causes of sudden death.
Cyclic approximation to stasis
Directory of Open Access Journals (Sweden)
Stewart D. Johnson
2009-06-01
Full Text Available Neighborhoods of points in $mathbb{R}^n$ where a positive linear combination of $C^1$ vector fields sum to zero contain, generically, cyclic trajectories that switch between the vector fields. Such points are called stasis points, and the approximating switching cycle can be chosen so that the timing of the switches exactly matches the positive linear weighting. In the case of two vector fields, the stasis points form one-dimensional $C^1$ manifolds containing nearby families of two-cycles. The generic case of two flows in $mathbb{R}^3$ can be diffeomorphed to a standard form with cubic curves as trajectories.
International Nuclear Information System (INIS)
El Sawi, M.
1983-07-01
A simple approach employing properties of solutions of differential equations is adopted to derive an appropriate extension of the WKBJ method. Some of the earlier techniques that are commonly in use are unified, whereby the general approximate solution to a second-order homogeneous linear differential equation is presented in a standard form that is valid for all orders. In comparison to other methods, the present one is shown to be leading in the order of iteration, and thus possibly has the ability of accelerating the convergence of the solution. The method is also extended for the solution of inhomogeneous equations. (author)
The relaxation time approximation
International Nuclear Information System (INIS)
Gairola, R.P.; Indu, B.D.
1991-01-01
A plausible approximation has been made to estimate the relaxation time from a knowledge of the transition probability of phonons from one state (r vector, q vector) to other state (r' vector, q' vector), as a result of collision. The relaxation time, thus obtained, shows a strong dependence on temperature and weak dependence on the wave vector. In view of this dependence, relaxation time has been expressed in terms of a temperature Taylor's series in the first Brillouin zone. Consequently, a simple model for estimating the thermal conductivity is suggested. the calculations become much easier than the Callaway model. (author). 14 refs
Polynomial approximation on polytopes
Totik, Vilmos
2014-01-01
Polynomial approximation on convex polytopes in \\mathbf{R}^d is considered in uniform and L^p-norms. For an appropriate modulus of smoothness matching direct and converse estimates are proven. In the L^p-case so called strong direct and converse results are also verified. The equivalence of the moduli of smoothness with an appropriate K-functional follows as a consequence. The results solve a problem that was left open since the mid 1980s when some of the present findings were established for special, so-called simple polytopes.
Finite elements and approximation
Zienkiewicz, O C
2006-01-01
A powerful tool for the approximate solution of differential equations, the finite element is extensively used in industry and research. This book offers students of engineering and physics a comprehensive view of the principles involved, with numerous illustrative examples and exercises.Starting with continuum boundary value problems and the need for numerical discretization, the text examines finite difference methods, weighted residual methods in the context of continuous trial functions, and piecewise defined trial functions and the finite element method. Additional topics include higher o
Hearing Recovey in Patients Suffering Sudden Deafness
Directory of Open Access Journals (Sweden)
Parviz Eslami
1992-04-01
Full Text Available The study included 80 patients treated for sudden deafness over the last 5-7 years. Case history, laboratory findings, pure-tone audiogram and electronystagmography (ENG findings were noted. If any abnormalities had been recorded in ENG studies, the studies were redone. ORL status was redefined and audiograms were obtained in all patients. When becoming ill, the 80 patients had not differed from the normal population in common cardiovascular risk factors. None of them had had signs of viral infection (paired serum samples had been taken at 2-week intervals; routine examinations had been done for common viral antigens. As many as 31 of the 80 patients with acute hearing loss had had abnormalities such as spontaneous nystagmus (PN, hypoexcitability (HE and directional preponderance (DP in the bithermal caloric tests (+44 degrees C, + 30 degrees C of their ENG studies. Twenty of the 31 patients still had abnormal ENG studies after 5-7 years. Only 1 subject had positional nystagmus, and none had subjective vertigo. Patients with an abnormal ENG study showed a poor recovery of the speech reception threshold, whereas those with a normal ENG study showed slightly significant (p less than 0.05 recovery.
Approximate Bayesian computation.
Directory of Open Access Journals (Sweden)
Mikael Sunnåker
Full Text Available Approximate Bayesian computation (ABC constitutes a class of computational methods rooted in Bayesian statistics. In all model-based statistical inference, the likelihood function is of central importance, since it expresses the probability of the observed data under a particular statistical model, and thus quantifies the support data lend to particular values of parameters and to choices among different models. For simple models, an analytical formula for the likelihood function can typically be derived. However, for more complex models, an analytical formula might be elusive or the likelihood function might be computationally very costly to evaluate. ABC methods bypass the evaluation of the likelihood function. In this way, ABC methods widen the realm of models for which statistical inference can be considered. ABC methods are mathematically well-founded, but they inevitably make assumptions and approximations whose impact needs to be carefully assessed. Furthermore, the wider application domain of ABC exacerbates the challenges of parameter estimation and model selection. ABC has rapidly gained popularity over the last years and in particular for the analysis of complex problems arising in biological sciences (e.g., in population genetics, ecology, epidemiology, and systems biology.
Energy Technology Data Exchange (ETDEWEB)
Sato, T [Hyogo Coll. of Medicine, Hyogo (Japan). Dept. of Physics
1975-01-01
Sudden fsub(min) enhancements (SFsub(m)E's) and sudden cosmic noise absorptions (SCNA's) associated with increments of X-ray fluxes during solar flares are studied on the basis of X-ray flux data measured by SOLRAD 9 and 10 satellites. Some statistical analyses on SFsub(m)E's observed at five observatories in Japan, corresponding to increased X-ray fluxes in the 1-8 A band are made for 50 solar flare events during the period January 1972 to December 1973, and value of fsub(min) is expressed as functions of cos x(x; solar zenith angle) and 1-8 A band X-ray flux. Similar study is also made for SCNA's observed by 30 MHz riometer at Hiraiso for 15 great solar flare events during the same period, together with 27.6 MHz riometer data reported by Schwentek (1973) and 18 MHz data published by Deshpande and Mitra (1972b). It is found that fsub(min) value (MHz) and SCNA value (L, dB) of a radio wave with frequency f(MHz) are related to X-ray flux (F/sub 0/, erg cm/sup -2/ sec/sup -1/) in the 1-8 A band and to cos x, by following approximate expressions, fsub(min)(MHz)=10F/sub 0/sup(1/4) cossup(1/2) x, and L(dB)=4.37x10/sup 3/f/sup -2/F/sub 0/sup(1/2) cos x, respectively. Blackout seems to occur for F/sub 0/ values causing fsub(min)'s greater than about 5 MHz. It is shown that these expressions can be derived from a brief theoretical calculation of radio wave absorption in the lower ionosphere. Also it is suggested that threshold X-ray fluxes in the 1-8 A band which may produce a minimum SFsub(m)E (2 MHz), blackout and minimum SCNA (0.27-0.36 dB for 30 MHz noise) are 1.6x10/sup -3/, 6.2x10/sup -2/ and (3-8) x 10/sup -3/ erg cm/sup -2/ sec/sup -1/, respectively, for cos x=1.
The random phase approximation
International Nuclear Information System (INIS)
Schuck, P.
1985-01-01
RPA is the adequate theory to describe vibrations of the nucleus of very small amplitudes. These vibrations can either be forced by an external electromagnetic field or can be eigenmodes of the nucleus. In a one dimensional analogue the potential corresponding to such eigenmodes of very small amplitude should be rather stiff otherwise the motion risks to be a large amplitude one and to enter a region where the approximation is not valid. This means that nuclei which are supposedly well described by RPA must have a very stable groundstate configuration (must e.g. be very stiff against deformation). This is usually the case for doubly magic nuclei or close to magic nuclei which are in the middle of proton and neutron shells which develop a very stable groundstate deformation; we take the deformation as an example but there are many other possible degrees of freedom as, for example, compression modes, isovector degrees of freedom, spin degrees of freedom, and many more
The quasilocalized charge approximation
International Nuclear Information System (INIS)
Kalman, G J; Golden, K I; Donko, Z; Hartmann, P
2005-01-01
The quasilocalized charge approximation (QLCA) has been used for some time as a formalism for the calculation of the dielectric response and for determining the collective mode dispersion in strongly coupled Coulomb and Yukawa liquids. The approach is based on a microscopic model in which the charges are quasilocalized on a short-time scale in local potential fluctuations. We review the conceptual basis and theoretical structure of the QLC approach and together with recent results from molecular dynamics simulations that corroborate and quantify the theoretical concepts. We also summarize the major applications of the QLCA to various physical systems, combined with the corresponding results of the molecular dynamics simulations and point out the general agreement and instances of disagreement between the two
Alcohol, cardiac arrhythmias and sudden death.
Kupari, M; Koskinen, P
1998-01-01
Studies in experimental animals have shown varying and apparently opposite effects of alcohol on cardiac rhythm and conduction. Given acutely to non-alcoholic animals, ethanol may even have anti-arrhythmic properties whereas chronic administration clearly increases the animals' susceptibility to cardiac arrhythmias. Chronic heavy alcohol use has been incriminated in the genesis of cardiac arrhythmias in humans. The evidence has come from clinical observations, retrospective case-control studies, controlled studies of consecutive admissions for arrhythmias, and prospective epidemiological investigations. Furthermore, electrophysiological studies have shown that acute alcohol administration facilitates the induction of tachyarrhythmias in selected heavy drinkers. The role of alcohol appears particularly conspicuous in idiopathic atrial fibrillation. Occasionally, ventricular tachyarrhythmias have also been provoked by alcohol intake. Several lines of evidence suggest that heavy drinking increases the risk of sudden cardiac death with fatal arrhythmia as the most likely mechanism. According to epidemiological studies this effect appears most prominent in middle-aged men and is only partly explained by confounding traits such as smoking and social class. The basic arrhythmogenic effects of alcohol are still insufficiently delineated. Subclinical heart muscle injury from chronic heavy use may be instrumental in producing patchy delays in conduction. The hyperadrenergic state of drinking and withdrawal may also contribute, as may electrolyte abnormalities, impaired vagal heart rate control, repolarization abnormalities with prolonged QT intervals and worsening of myocardial ischaemia or sleep apnoea. Most of what we know about alcohol and arrhythmias relates to heavy drinking. The effect of social drinking on clinical arrhythmias in non-alcoholic cardiac patients needs to be addressed further.
Social phobia with sudden onset--post-panic social phobia?
DEFF Research Database (Denmark)
Kristensen, Ann Suhl; Mortensen, Erik Lykke; Mors, Ole
2008-01-01
Overlap between social phobia (SP) and panic disorder (PD) has been observed in epidemiological, family, and challenge studies. One possible explanation is that some cases of SP develop as a consequence of a panic attack in a social situation. By definition, these cases of SP have sudden onset...... recruited as part of an etiological study. Patients with SP with sudden onset did, as hypothesized, differ from patients with SP without sudden onset with regard to age of onset and extraversion, but not with regard to symptoms. They did not differ markedly from patients with comorbid SP and PD. The concept...
Approximate quantum Markov chains
Sutter, David
2018-01-01
This book is an introduction to quantum Markov chains and explains how this concept is connected to the question of how well a lost quantum mechanical system can be recovered from a correlated subsystem. To achieve this goal, we strengthen the data-processing inequality such that it reveals a statement about the reconstruction of lost information. The main difficulty in order to understand the behavior of quantum Markov chains arises from the fact that quantum mechanical operators do not commute in general. As a result we start by explaining two techniques of how to deal with non-commuting matrices: the spectral pinching method and complex interpolation theory. Once the reader is familiar with these techniques a novel inequality is presented that extends the celebrated Golden-Thompson inequality to arbitrarily many matrices. This inequality is the key ingredient in understanding approximate quantum Markov chains and it answers a question from matrix analysis that was open since 1973, i.e., if Lieb's triple ma...
Prestack traveltime approximations
Alkhalifah, Tariq Ali
2012-05-01
Many of the explicit prestack traveltime relations used in practice are based on homogeneous (or semi-homogenous, possibly effective) media approximations. This includes the multifocusing, based on the double square-root (DSR) equation, and the common reflection stack (CRS) approaches. Using the DSR equation, I constructed the associated eikonal form in the general source-receiver domain. Like its wave-equation counterpart, it suffers from a critical singularity for horizontally traveling waves. As a result, I recasted the eikonal in terms of the reflection angle, and thus, derived expansion based solutions of this eikonal in terms of the difference between the source and receiver velocities in a generally inhomogenous background medium. The zero-order term solution, corresponding to ignoring the lateral velocity variation in estimating the prestack part, is free of singularities and can be used to estimate traveltimes for small to moderate offsets (or reflection angles) in a generally inhomogeneous medium. The higher-order terms include limitations for horizontally traveling waves, however, we can readily enforce stability constraints to avoid such singularities. In fact, another expansion over reflection angle can help us avoid these singularities by requiring the source and receiver velocities to be different. On the other hand, expansions in terms of reflection angles result in singularity free equations. For a homogenous background medium, as a test, the solutions are reasonably accurate to large reflection and dip angles. A Marmousi example demonstrated the usefulness and versatility of the formulation. © 2012 Society of Exploration Geophysicists.
The epidemiology of sudden oak death in Oregon forests
Ebba K. Peterson
2011-01-01
The phytopathogen Phytophthora ramorum (Werres, DeCock & Man in't Veld), causal agent of Sudden Oak Death (SOD) of oaks (Quercus spp.) and tanoaks (Notholithocarpus densiflorus syn. Lithocarpus densiflorus...
Immunization safety review: vaccinations and sudden unexpected death in infancy
National Research Council Canada - National Science Library
Institute of Medicine (U.S.). Immunization Safety Review Committee; Stratton, Kathleen R
2003-01-01
...), and neonatal death (infant death, whether sudden or not, during the first 4 weeks of life). Based on this review, the committee concluded that the evidence favors rejection of a causal relationship between some vaccines and SIDS...
CAUSES OF SUDDEN NATURAL DEATH: A MEDICO-LEGAL ...
African Journals Online (AJOL)
89 No. 10 October 2012 ... The age range of the cases was 19-105 years with a mean age ... majority of cases (39.3%), the cause of death was related to the cardio-vascular ... Six hundred and twenty six cases of sudden natural .... (39/60) and a mean age of 54.2±15years. ..... D. A population-based autopsy study of sudden,.
Geomagnetic response to sudden expansions of the magnetosphere
International Nuclear Information System (INIS)
Araki, Tohru; Nagano, Hiroshi
1988-01-01
The geomagnetic response to five successive sudden expansions of the magnetosphere was examined by the use of magnetic data observed on the ground and by satellites. At the geosynchronous orbit between 0800 and 1100 LT the magnetic field component parallel to Earth's rotation axis decreased successively. The amplitude and the fall time of each decrease were 20-30 nT and 2.5-3.5 min, respectively. The decrease was propagated about 10 min later to the distance of about 31 R E from Earth in the antisunward direction, indicating propagation speed of about 300 km/s. The H component of ground magnetograms from low-latitude stations showed decreases with waveform similar to that at the geosynchronous orbit, but each decrease at the dayside equator was greatly enhanced and preceded by a short small positive impulse. Each of the corresponding geomagnetic variations at high latitude stations consisted of two successive sharp pulses of opposite sense with 2-3 min duration. The dominant component and the sense of these high-latitude pulses were highly dependent upon local time and latitude. The distribution of equivalent ionospheric current arrows for each high-latitude pulse showed clear twin vortices centered at 70-76 degree geomagnetic latitude in the dayside and was approximately symmetric with respect to the noon meridian. The current direction of the vortices was reversed from the first pulse to the second. it suggests successive appearance of a dawn-to-dusk and then a dusk-to-dawn electric field, both of which were transmitted from the magnetosphere to the polar ionosphere. The effect of ionospheric currents due to these polar electric fields was superposed on the simple magnetic decrease produced by an expansion of the whole magnetosphere and produced the complex waveform distribution on the ground
Gastrointestinal causes of sudden unexpected death: A review.
Menezes, Ritesh G; Ahmed, Saba; Pasha, Syed Bilal; Hussain, Syed Ather; Fatima, Huda; Kharoshah, Magdy A; Madadin, Mohammed
2018-01-01
Gastrointestinal conditions are a less common cause of sudden unexpected death when compared to other conditions such as cardiovascular conditions, but they are equally important. Various congenital and acquired gastrointestinal conditions that have resulted in sudden unexpected death are discussed. The possible lethal mechanisms behind each condition, along with any associated risk factors or secondary diseases, have been described. Through this article, we aim to highlight the need for physicians to prevent death in such conditions by ensuring that subclinical cases are diagnosed correctly before it is too late and by providing timely and efficacious treatment to the patient concerned. In addition, this review would certainly benefit the forensic pathologist while dealing with cases of sudden unexpected death due to gastrointestinal causes. This article is a review of the major gastrointestinal causes of sudden unexpected death. In addition, related fatal cases encountered occasionally in forensic autopsy practice are also included. There are several unusual and rare causes of life-threatening gastrointestinal bleeding that may lead to sudden unexpected death to cover all the entities in detail. Nevertheless, this article is a general guide to the topic of gastrointestinal causes of sudden unexpected death.
Declining risk of sudden death in heart failure
DEFF Research Database (Denmark)
Shen, Li; Jhund, Pardeep S.; Petrie, Mark C.
2017-01-01
BACKGROUND The risk of sudden death has changed over time among patients with symptomatic heart failure and reduced ejection fraction with the sequential introduction of medications including angiotensin-converting-enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, and mineralocorti......BACKGROUND The risk of sudden death has changed over time among patients with symptomatic heart failure and reduced ejection fraction with the sequential introduction of medications including angiotensin-converting-enzyme inhibitors, angiotensin-receptor blockers, beta...... cardioverter-defibrillator at the time of trial enrollment were excluded. Weighted multivariable regression was used to examine trends in rates of sudden death over time. Adjusted hazard ratios for sudden death in each trial group were calculated with the use of Cox regression models. The cumulative incidence...... rates of sudden death were assessed at different time points after randomization and according to the length of time between the diagnosis of heart failure and randomization. RESULTS Sudden death was reported in 3583 patients. Such patients were older and were more often male, with an ischemic cause...
Self-similar factor approximants
International Nuclear Information System (INIS)
Gluzman, S.; Yukalov, V.I.; Sornette, D.
2003-01-01
The problem of reconstructing functions from their asymptotic expansions in powers of a small variable is addressed by deriving an improved type of approximants. The derivation is based on the self-similar approximation theory, which presents the passage from one approximant to another as the motion realized by a dynamical system with the property of group self-similarity. The derived approximants, because of their form, are called self-similar factor approximants. These complement the obtained earlier self-similar exponential approximants and self-similar root approximants. The specific feature of self-similar factor approximants is that their control functions, providing convergence of the computational algorithm, are completely defined from the accuracy-through-order conditions. These approximants contain the Pade approximants as a particular case, and in some limit they can be reduced to the self-similar exponential approximants previously introduced by two of us. It is proved that the self-similar factor approximants are able to reproduce exactly a wide class of functions, which include a variety of nonalgebraic functions. For other functions, not pertaining to this exactly reproducible class, the factor approximants provide very accurate approximations, whose accuracy surpasses significantly that of the most accurate Pade approximants. This is illustrated by a number of examples showing the generality and accuracy of the factor approximants even when conventional techniques meet serious difficulties
International Conference Approximation Theory XV
Schumaker, Larry
2017-01-01
These proceedings are based on papers presented at the international conference Approximation Theory XV, which was held May 22–25, 2016 in San Antonio, Texas. The conference was the fifteenth in a series of meetings in Approximation Theory held at various locations in the United States, and was attended by 146 participants. The book contains longer survey papers by some of the invited speakers covering topics such as compressive sensing, isogeometric analysis, and scaling limits of polynomials and entire functions of exponential type. The book also includes papers on a variety of current topics in Approximation Theory drawn from areas such as advances in kernel approximation with applications, approximation theory and algebraic geometry, multivariate splines for applications, practical function approximation, approximation of PDEs, wavelets and framelets with applications, approximation theory in signal processing, compressive sensing, rational interpolation, spline approximation in isogeometric analysis, a...
Hierarchical low-rank approximation for high dimensional approximation
Nouy, Anthony
2016-01-01
Tensor methods are among the most prominent tools for the numerical solution of high-dimensional problems where functions of multiple variables have to be approximated. Such high-dimensional approximation problems naturally arise in stochastic analysis and uncertainty quantification. In many practical situations, the approximation of high-dimensional functions is made computationally tractable by using rank-structured approximations. In this talk, we present algorithms for the approximation in hierarchical tensor format using statistical methods. Sparse representations in a given tensor format are obtained with adaptive or convex relaxation methods, with a selection of parameters using crossvalidation methods.
Hierarchical low-rank approximation for high dimensional approximation
Nouy, Anthony
2016-01-07
Tensor methods are among the most prominent tools for the numerical solution of high-dimensional problems where functions of multiple variables have to be approximated. Such high-dimensional approximation problems naturally arise in stochastic analysis and uncertainty quantification. In many practical situations, the approximation of high-dimensional functions is made computationally tractable by using rank-structured approximations. In this talk, we present algorithms for the approximation in hierarchical tensor format using statistical methods. Sparse representations in a given tensor format are obtained with adaptive or convex relaxation methods, with a selection of parameters using crossvalidation methods.
Sudden Cardiac Arrest during Participation in Competitive Sports.
Landry, Cameron H; Allan, Katherine S; Connelly, Kim A; Cunningham, Kris; Morrison, Laurie J; Dorian, Paul
2017-11-16
The incidence of sudden cardiac arrest during participation in sports activities remains unknown. Preparticipation screening programs aimed at preventing sudden cardiac arrest during sports activities are thought to be able to identify at-risk athletes; however, the efficacy of these programs remains controversial. We sought to identify all sudden cardiac arrests that occurred during participation in sports activities within a specific region of Canada and to determine their causes. In this retrospective study, we used the Rescu Epistry cardiac arrest database (which contains records of every cardiac arrest attended by paramedics in the network region) to identify all out-of-hospital cardiac arrests that occurred from 2009 through 2014 in persons 12 to 45 years of age during participation in a sport. Cases were adjudicated as sudden cardiac arrest (i.e., having a cardiac cause) or as an event resulting from a noncardiac cause, on the basis of records from multiple sources, including ambulance call reports, autopsy reports, in-hospital data, and records of direct interviews with patients or family members. Over the course of 18.5 million person-years of observation, 74 sudden cardiac arrests occurred during participation in a sport; of these, 16 occurred during competitive sports and 58 occurred during noncompetitive sports. The incidence of sudden cardiac arrest during competitive sports was 0.76 cases per 100,000 athlete-years, with 43.8% of the athletes surviving until they were discharged from the hospital. Among the competitive athletes, two deaths were attributed to hypertrophic cardiomyopathy and none to arrhythmogenic right ventricular cardiomyopathy. Three cases of sudden cardiac arrest that occurred during participation in competitive sports were determined to have been potentially identifiable if the athletes had undergone preparticipation screening. In our study involving persons who had out-of-hospital cardiac arrest, the incidence of sudden cardiac
Risk factors and causes of sudden noncardiac death
DEFF Research Database (Denmark)
Risgaard, Bjarke; Lynge, Thomas Hadberg; Wissenberg, Mads
2015-01-01
was to report the risk factors and causes of SNCD. METHODS: We conducted a retrospective, nationwide study including all deaths between 2000 and 2006 of individuals aged 1-35 years and all deaths between 2007 and 2009 of individuals aged 1-49 years. Two physicians identified all sudden death cases through.......3-2.3; OR 3.0, 95% CI 2.0-4.4; and OR 4.3, 95% CI 2.5-7.4, respectively). The most common cause of SNCD was pulmonary disease (n = 115 [40%]). CONCLUSION: Sudden death among individuals aged caused by noncardiac diseases in 28% of cases. Risk factors were female sex, age, and the absence......BACKGROUND: On the performance of an autopsy, sudden deaths may be divided into 2 classifications: (1) sudden cardiac deaths and (2) sudden noncardiac deaths (SNCDs). Families of SNCD victims should not be followed up as a means of searching for cardiac disease. OBJECTIVE: The purpose of this study...
Major life events as potential triggers of sudden cardiac arrest.
Wicks, April F; Lumley, Thomas; Lemaitre, Rozenn N; Sotoodehnia, Nona; Rea, Thomas D; McKnight, Barbara; Strogatz, David S; Bovbjerg, Viktor E; Siscovick, David S
2012-05-01
We investigated the risk of sudden cardiac arrest in association with the recent loss of, or separation from, a family member or friend. Our case-crossover study included 490 apparently healthy married residents of King County, Washington, who suffered sudden cardiac arrest between 1988 and 2005. We compared exposure to spouse-reported family/friend events occurring ≤ 1 month before sudden cardiac arrest with events occurring in the previous 5 months. We evaluated potential effect modification by habitual vigorous physical activity. Recent family/friend events were associated with a higher risk of sudden cardiac arrest (odds ratio [OR] = 1.6; 95% confidence interval [CI] = 1.1-2.4). ORs for cases with and without habitual vigorous physical activity were 1.1 (0.6-2.2) and 2.0 (1.2-3.1), respectively (interaction P = 0.02). These results suggest family/friend events may trigger sudden cardiac arrest and raise the hypothesis that habitual vigorous physical activity may lower susceptibility to these potential triggers.
Forms of Approximate Radiation Transport
Brunner, G
2002-01-01
Photon radiation transport is described by the Boltzmann equation. Because this equation is difficult to solve, many different approximate forms have been implemented in computer codes. Several of the most common approximations are reviewed, and test problems illustrate the characteristics of each of the approximations. This document is designed as a tutorial so that code users can make an educated choice about which form of approximate radiation transport to use for their particular simulation.
Approximation by planar elastic curves
DEFF Research Database (Denmark)
Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge
2016-01-01
We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....
Exact constants in approximation theory
Korneichuk, N
1991-01-01
This book is intended as a self-contained introduction for non-specialists, or as a reference work for experts, to the particular area of approximation theory that is concerned with exact constants. The results apply mainly to extremal problems in approximation theory, which in turn are closely related to numerical analysis and optimization. The book encompasses a wide range of questions and problems: best approximation by polynomials and splines; linear approximation methods, such as spline-approximation; optimal reconstruction of functions and linear functionals. Many of the results are base
International Conference Approximation Theory XIV
Schumaker, Larry
2014-01-01
This volume developed from papers presented at the international conference Approximation Theory XIV, held April 7–10, 2013 in San Antonio, Texas. The proceedings contains surveys by invited speakers, covering topics such as splines on non-tensor-product meshes, Wachspress and mean value coordinates, curvelets and shearlets, barycentric interpolation, and polynomial approximation on spheres and balls. Other contributed papers address a variety of current topics in approximation theory, including eigenvalue sequences of positive integral operators, image registration, and support vector machines. This book will be of interest to mathematicians, engineers, and computer scientists working in approximation theory, computer-aided geometric design, numerical analysis, and related approximation areas.
Sudden death due to inhalant abuse in youth: Case report
Directory of Open Access Journals (Sweden)
Ramazan Akcan
2010-06-01
Full Text Available Intentional inhalation or abuse of volatile substances is a common public health problem all over the world. As these substances generate euphoria frequency of use among adolescents and young adults is increasing steadily. In cases using inhalants to achieve a euphoric state -without knowing possible consequences- sudden death may occurdue to acute cardio-pulmonary dysfunction.Here we present a case of sudden death of a nineteen-year-old female due to inhalation of volatile from butane containing lighter gas tube, with the findings of autopsy and death scene investigation.In the context of this case; it was aimed to draw attention to the risk of sudden death and steady increase of frequencyof volatile substance abuse among adolescents and young adults due to various psycho-social factors.
Sudden Death: An Uncommon Occurrence in Dementia with Lewy Bodies.
Molenaar, Joery P; Wilbers, Joyce; Aerts, Marjolein B; Leijten, Quinten H; van Dijk, Jan G; Esselink, Rianne A; Bloem, Bastiaan R
2016-01-01
We present a 75-year-old woman with dementia and parkinsonism who developed severe orthostatic hypotension and eventually died. Autopsy revealed extensive Lewy body formation in the midbrain, limbic system, intermediate spinal cord, and medulla oblongata. Furthermore, a vast amount of Lewy bodies was seen in the paravertebral sympathetic ganglia which likely explained the severe autonomic failure. We speculate that this autonomic failure caused sudden death through dysregulation of respiration or heart rhythm, reminiscent of sudden death in multiple system atrophy (MSA). Clinicians should be aware of this complication in patients presenting with parkinsonism and autonomic dysfunction, and that sudden death may occur in dementia with Lewy bodies (DLB) as it does in MSA.
Post-mortem toxicology in young sudden cardiac death victims
DEFF Research Database (Denmark)
Bjune, Thea; Risgaard, Bjarke; Kruckow, Line
2017-01-01
Aims: Several drugs increase the risk of ventricular fibrillation and sudden cardiac death (SCD). We aimed to investigate in detail the toxicological findings of all young SCD throughout Denmark. Methods and results: Deaths in persons aged 1-49 years were included over a 10-year period. Death...... certificates and autopsy reports were retrieved and read to identify cases of sudden death and establish cause of death. All medico-legal autopsied SCD were included and toxicological reports collected. Positive toxicology was defined as the presence of any substance (licit and/or illicit). All toxicological...... findings had previously been evaluated not to have caused the death (i.e. lethal concentrations were excluded). We identified 620 medico-legal autopsied cases of SCD, of which 77% (n = 477) were toxicologically investigated post-mortem, and 57% (n = 270) had a positive toxicology profile. Sudden cardiac...
CARDIOVASCULAR CAUSES OF SUDDEN DEATH- AN AUTOPSY STUDY
Directory of Open Access Journals (Sweden)
Deepu Thankappan
2016-10-01
Full Text Available BACKGROUND Present study “Cardiovascular Causes of Sudden Death- An Autopsy Study” was a cross-sectional study conducted in Department of Forensic Medicine, Government Medical College, Kottayam, during the time period from June 1 st 2013 to June 1 st 2014. The objective of the study was to find out the cardiovascular causes of sudden deaths and to correlate the postmortem findings with the histopathological examination. 57 cases brought for postmortem examination with history suggestive of sudden natural death were taken into the study and those cases observed to have a cardiovascular cause of sudden death during autopsy were further examined and their heart specimens were subjected to histopathological examination. Then, the sociodemographic factors, postmortem findings and histopathological findings were correlated and analysed. MATERIALS AND METHODS 57 cases brought for autopsy at Department of Forensic Medicine, Government Medical College, Kottayam from 01.06.2013 to 31.05.2014 were autopsied and subjected to histopathological examination of the heart. The socio-demographic data were collected; they were analyzed and correlated with the postmortem and histopathological findings. RESULTS Out of the 57 subjects who were taken into the study, maximum number of Sudden natural deaths were in the 36-50 year age group (42.2%, 33.3% in the 51-65 year age group and 14% of cases were in the 66-80 year age group. CONCLUSION Histopathological examination of the samples showed myocardial infarction in 33.3% of cases; chronic ischaemic heart disease in 56.1% of cases and myocarditis in 19.3% of cases. The major cardiovascular cause of sudden death was ascertained as Coronary artery disease.
International Nuclear Information System (INIS)
Ngo, H.; Ngo, C.
1980-04-01
We have calculated the interaction potential between two heavy ions using the energy density formalism and Fermi distributions for the nuclear densities. The experimental fusion barriers are rather well reproduced. The conditions for the observation of fusion between two heavy ions is discussed. As far as the nuclear part of the interaction potential is concerned, the proximity scaling is investigated in details. It is found that the proximity theorem is satisfied to a good extent. However, as far as the neutron excess is concerned, a disagreement with the proximity potential is observed
Current state of the problem sudden infant death at home
Berlay Margarita Vasilievna; Kopylov Anatoliy Vasilievich; Karpov Sergey Mikhailovich
2017-01-01
The “Sudden Infant Death Syndrome” stands for unexpected nonviolent death of apparently healthy chest age child when there is no history or pathomorphological features which can be adequate explanations for death reasons. In Russian Federation, the death rate from this syndrome in the range of 0,06 to 2,8 per 1000 live births. In Stavropol region, average figures are equal to 0,36 per 1000 live births in the period of 2005–2014. Rates of incidence sudden infant death syndrome are similar to t...
Some results in Diophantine approximation
DEFF Research Database (Denmark)
Pedersen, Steffen Højris
the basic concepts on which the papers build. Among other it introduces metric Diophantine approximation, Mahler’s approach on algebraic approximation, the Hausdorff measure, and properties of the formal Laurent series over Fq. The introduction ends with a discussion on Mahler’s problem when considered......This thesis consists of three papers in Diophantine approximation, a subbranch of number theory. Preceding these papers is an introduction to various aspects of Diophantine approximation and formal Laurent series over Fq and a summary of each of the three papers. The introduction introduces...
Limitations of shallow nets approximation.
Lin, Shao-Bo
2017-10-01
In this paper, we aim at analyzing the approximation abilities of shallow networks in reproducing kernel Hilbert spaces (RKHSs). We prove that there is a probability measure such that the achievable lower bound for approximating by shallow nets can be realized for all functions in balls of reproducing kernel Hilbert space with high probability, which is different with the classical minimax approximation error estimates. This result together with the existing approximation results for deep nets shows the limitations for shallow nets and provides a theoretical explanation on why deep nets perform better than shallow nets. Copyright © 2017 Elsevier Ltd. All rights reserved.
Sudden oak death disease progression in oaks and tanoaks
Brice A. McPherson; Sylvia R. Mori; David L. Wood; Andrew J. Storer; Pavel Svihra; N. Maggi Kelly; Richard B. Standiford
2006-01-01
In March 2000, we established twenty disease progression plots in Marin County to monitor the progress of sudden oak death symptoms in coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and tanoak (Lithocarpus densiflorus) (McPherson and others 2005). Plots were located to encompass a...
Sudden death amongst people practicing competitive sports (Review Article
Directory of Open Access Journals (Sweden)
Bartłomiej Wrzesiński
2018-02-01
Full Text Available Sudden cardiac death is and unexpected cardiac arrest that may occur both during exercise and also an hour after its completion. It most often occurs in young sportsmen under 35 years of age and is usually associated with improperly performed physical activity proceeded by lack of specialized medical examination and research. Natural and cardiac causes are two basic phenomena that lead to cardiac death. As confirmed by Framingham Heart Study, conducted in the eighties of the twentieth century on the population of Americans, natural causes accounted for 13% while cardiac causes accounted for 88% off all. The statistics of the largest centers of sport medicine are presented as follows: Germany – 1 death per 200,000 people practicing sports (total while United States of America – 1 death per 80,000 people per year. The problem of of sudden deaths is and important topic worthy of a broader and more specific analysis. It should be noted that physical exertion is not is not a direct cause of sudden deaths. Currently the most research concerns professional athletes who have extensive support and knowledge about the exercise they perform. The main problem concerning subject of sudden deaths are not diagnosed hearth defects. Additional topic of interest is rarity of medical tests performed by amateur athletes and athletes at the lower levels of competition. Such athletes do not have as extensive knowledge as their experienced idols, which may bring tragic consequences.
About a cocaine-associated sudden death casework.
Pileggi, P; Teatino, A; La Marca, A; Barbaro, A
2004-12-02
A man 24-year-old died suddenly while he was doing shopping. It was supposed that the death was caused by ictus or by cardiac pathology. During the autopsy, some biological samples were taken (hair, urine, blood and lachrymal liquid) for the toxicological analysis and also the heart, some fragments from the liver, lungs, spleen, and kidneys for the histo-pathological analysis.
Vasculopathic Cranial Ocular Motor Neuropathy Following Sudden Emotional Stress
Purvin, Valerie
2010-01-01
We describe three patients who experienced onset of a microvascular ocular motor nerve palsy in the setting of sudden emotional stress. Such emotional states are accompanied by a marked increase in sympathetic tone in some individuals. Mechanisms by which these autonomic changes might produce an ischemic cranial nerve palsy include intra-cranial vasoconstriction and transient systemic hypotension due to alterations in cardiac function.
Circumvention of suddenly appearing obstacles in young and older adults
Pijnappels, M.; Kingma, I.; Van Dieën, J. H.
2010-01-01
Reduced ability to circumvent an obstacle, which is noticed only shortly before collision, could be a cause of falls and injury, especially in older adults. In this study, we investigated differences in strategies and their characteristics between young and older adults when circumventing a suddenly
Left ventricular cardiac myxoma and sudden death in a dog
de Nijs, M.I.; Vink, Aryan; Bergmann, W.; Szatmári, V.
2016-01-01
Background: Myxoma is a very rare benign cardiac tumor in dogs. This is the first description of a cardiac myxoma originating from the left ventricular outflow tract, presumably causing sudden death. Case presentation: A previously healthy 12-year-old male West Highland white terrier was found dead
Left ventricular cardiac myxoma and sudden death in a dog
de Nijs, Maria Irene; Vink, Aryan; Bergmann, Wilhelmina; Szatmári, Viktor
2016-01-01
BACKGROUND: Myxoma is a very rare benign cardiac tumor in dogs. This is the first description of a cardiac myxoma originating from the left ventricular outflow tract, presumably causing sudden death. CASE PRESENTATION: A previously healthy 12-year-old male West Highland white terrier was found dead
Picture quiz: a case of sudden severe chest pain.
Rabia, Mustafa Abu; Sullivan, P; Stivaros, Stavros M
2007-01-01
An 18-year-old male with no previous medical history presented to hospital with sudden onset of acute epigastric pain radiating to the anterior chest wall and both shoulders. There was no history of recent trauma and he had not been vomiting.
Relationship between coronary atherosclerosis and 'sudden cardiac death'
International Nuclear Information System (INIS)
Lundholm, C.E.; Sundbom, L.; Lundholm, L.
1989-01-01
Coronary arteriosclerosis in mini-pigs was produced by combination of hypercholesterolemia and twofold X irradiation of the cardiac region. 15-21 weeks following irradiation 40% of the adult animals and 58% of the juvenils died of 'sudden cardiac death'. The mortality rate decreased significantly after application of the calcium-channel blocking agent nifedipine
Sudden unilateral deafness with endolymphatic sac adenocarcinoma: MRI
Energy Technology Data Exchange (ETDEWEB)
Gaeta, M.; Blandino, A.; Minutoli, F.; Pandolfo, I. [Inst. of Radiological Sciences, Univ. of Messina (Italy)
1999-10-01
A 30-year-old man presented with sudden left deafness and vertigo. CT showed an osteolytic retrolabyrinthine tumour of the left temporal bone. High signal from the tumour and labyrinth was seen on fat-suppressed T 1-weighted images. At surgery, a haemorrhagic papillary-cystic adenocarcinoma of the endolymphatic sac was found. (orig.)
Sudden unilateral deafness with endolymphatic sac adenocarcinoma: MRI
International Nuclear Information System (INIS)
Gaeta, M.; Blandino, A.; Minutoli, F.; Pandolfo, I.
1999-01-01
A 30-year-old man presented with sudden left deafness and vertigo. CT showed an osteolytic retrolabyrinthine tumour of the left temporal bone. High signal from the tumour and labyrinth was seen on fat-suppressed T 1-weighted images. At surgery, a haemorrhagic papillary-cystic adenocarcinoma of the endolymphatic sac was found. (orig.)
Sudden oak death effects on the dynamics of dead wood
Richard C. Cobb; Jo& atilde; o Filipe A.N.; Margaret R. Metz; Ross K. Meentemeyer; David M. Rizzo
2013-01-01
Sudden oak death has impacted forests notable for high-fire risk and contiguous host communities in California and Oregon coastal forest ecosystems. The disease continues to emerge in stands and landscapes with a large biomass of tanoak (Notholithocarpus densiflorus (Hook.&Arn.) Manos, Cannon & S.H.Oh), and we show that woody debris also...
Guidelines for autopsy investigation of sudden cardiac death
Basso, Cristina; Burke, Margaret; Fornes, Paul; Gallagher, Patrick J.; de Gouveia, Rosa Henriques; Sheppard, Mary; Thiene, Gaetano; van der Wal, Allard
2010-01-01
Although sudden cardiac death is one of the most important mode of death in Western Countries, pathologists and public health physicians have not given this problem the attention it deserves. New methods of preventing potentially fatal arrhythmias have been developed, and the accurate diagnosis of
Guidelines for autopsy investigation of sudden cardiac death
Basso, C.; Burke, M.; Fornes, P.; Gallagher, P. J.; de Gouveia, R. H.; Sheppard, M.; Thiene, G.; van der Wal, A.
2010-01-01
Although sudden cardiac death is one of the most important mode of death in Western Countries, pathologists and public health physicians have not given this problem the attention it deserves. New methods of preventing potentially fatal arrhythmias have been developed and the accurate diagnosis of
Guidelines for autopsy investigation of sudden cardiac death
Basso, Cristina; Burke, Margaret; Fornes, Paul; Gallagher, Patrick J.; de Gouveia, Rosa Henriques; Sheppard, Mary; Thiene, Gaetano; van der Wal, Allard
2008-01-01
Although sudden cardiac death is one of the most important mode of death in Western Countries, pathologists and public health physicians have not given this problem the attention it deserves. New methods of preventing potentially fatal arrhythmias have been developed, and the accurate diagnosis of
Solar flare effects and storm sudden commencement even in ...
African Journals Online (AJOL)
1998-05-08
Variations in the three components of geomagnetic field were observed at the twenty-two geomagnetic Euro-African Observatories during the solar flare that occurred on the 6 May, 1998 at 0080UT and storm sudden commencement that took place on May 8, 1998 at 15.00 UT. The geomagnetic field on 6 May, 1998 was ...
Temporal epidemiology of sudden oak death in Oregon
Ebba K. Peterson; Everett M. Hansen; Alan Kanaskie
2015-01-01
An effort to eradicate Phytophthora ramorum, causal agent of sudden oak death, has been underway since its discovery in Oregon forests. Using an information-theoretical approach, we sought to model yearly variation in the size of newly infested areas and dispersal distance. Maximum dispersal distances were best modeled by spring and winter...
Collaboratively managing sudden oak death using tangible geospatial modeling
Ross K. Meentemeyer; Francesco Tonini; Douglas Shoemaker; Richard C. Cobb; Brendan A. Harmon; Vaclav Petras; Anna Petrasova; Helena Mitasova
2017-01-01
Failure to build consensus amongst stakeholders has been a primary obstacle barring progress in developing and implementing strategies to manage sudden oak death (SOD). Consensus as to the goals of in situ management of SOD has rarely been reached, because stakeholdersâ visions of success vary widely and often compete with each other...
Sudden infant death syndrome (SIDS)--standardised investigations and classification
DEFF Research Database (Denmark)
Bajanowski, Thomas; Vege, Ashild; Byard, Roger W
2007-01-01
Sudden infant death syndrome (SIDS) still accounts for considerable numbers of unexpected infant deaths in many countries. While numerous theories have been advanced to explain these events, it is increasingly clear that this group of infant deaths results from the complex interaction of a variet...
Sudden cardiac death and acute pathology of coronary arteries
van Dantzig, J. M.; Becker, A. E.
1986-01-01
The pathology of sudden cardiac death still is a matter of controversy, particularly with respect to the state of the coronary arteries. A recent study has shown a high incidence of acute lesions and suggests a causal relationship. The present study has been designed to verify whether or not acute
Guidelines for autopsy investigation of sudden cardiac death
DEFF Research Database (Denmark)
Basso, Cristina; Aguilera, Beatriz; Banner, Jytte
2017-01-01
diagnosis of the causes of SCD is now of particular importance. Pathologists are responsible for determining the precise cause and mechanism of sudden death but there is still considerable variation in the way in which they approach this increasingly complex task. The Association for European Cardiovascular...
Linking sudden oak death with spatial economic value transfer
Tom Holmes; Bill Smith
2008-01-01
Sudden oak death (caused by Phytophthora ramorum) is currently having a dramatic impact on the flow of ecosystem services provided by trees and forests in California. Timber species in California are not thought to be at risk of mortality from this pathogen and, consequently, economic impacts accrue to non-market values of trees such as aesthetics,...
Equatorial storm sudden commencements and interplanetary magnetic field
International Nuclear Information System (INIS)
Rastogi, R.G.
1980-01-01
A comparison is made of the signatures of interplanetary (IP) shocks in the B and theta plots of interplanetary magnetic field (IMF) data of satellites Explorer 33, 34 and 35 and in the H magnetograms at ground observatories within the equatorial electrojet belt, Huancayo, Addis Ababa and Trivandrum associated with major storm sudden commencements during 1967-70. The IP shocks showing sudden increase of the scalar value of IMF, i.e. B without any change of the latitude theta or with the southward turning of theta, were followed by a purely positive sudden increase of H, at any of the magnetic observatories, either on the dayside or the nightside of the earth. The IP shocks identified by a sudden increase of B and with the northward turning of the latitude theta (positive ΔBsub(z)) were associated with purely positive sudden commencement (SC) at the observatories in the nightside, but at the equatorial observatories in the dayside of the earth the signature of the shock was a SC in H with a preliminary negative impulse followed by the main positive excursion (SC-+). It is suggested that the SCs in H at low latitudes are composed of two effects, viz. (i) one due to hydromagnetic pressure on the magnetosphere by the solar plasma and (ii) the other due to the induced electric field associated with the solar wind velocity, V and the Z-component of the IP magnetic field (E = - V x Bsub(z)). The effect of magnetosphere electric field is faster than the effect due to the compression of the magnetosphere by the impinging solar plasma. The negative impulse of SC-+ at low latitude is seen at stations close to the dip equator and only during daytime due to the existence of high ionospheric conductivities in the equatorial electrojet region. (author)
A computer case definition for sudden cardiac death.
Chung, Cecilia P; Murray, Katherine T; Stein, C Michael; Hall, Kathi; Ray, Wayne A
2010-06-01
To facilitate studies of medications and sudden cardiac death, we developed and validated a computer case definition for these deaths. The study of community dwelling Tennessee Medicaid enrollees 30-74 years of age utilized a linked database with Medicaid inpatient/outpatient files, state death certificate files, and a state 'all-payers' hospital discharge file. The computerized case definition was developed from a retrospective cohort study of sudden cardiac deaths occurring between 1990 and 1993. Medical records for 926 potential cases had been adjudicated for this study to determine if they met the clinical definition for sudden cardiac death occurring in the community and were likely to be due to ventricular tachyarrhythmias. The computerized case definition included deaths with (1) no evidence of a terminal hospital admission/nursing home stay in any of the data sources; (2) an underlying cause of death code consistent with sudden cardiac death; and (3) no terminal procedures inconsistent with unresuscitated cardiac arrest. This definition was validated in an independent sample of 174 adjudicated deaths occurring between 1994 and 2005. The positive predictive value of the computer case definition was 86.0% in the development sample and 86.8% in the validation sample. The positive predictive value did not vary materially for deaths coded according to the ICO-9 (1994-1998, positive predictive value = 85.1%) or ICD-10 (1999-2005, 87.4%) systems. A computerized Medicaid database, linked with death certificate files and a state hospital discharge database, can be used for a computer case definition of sudden cardiac death. Copyright (c) 2009 John Wiley & Sons, Ltd.
The most common cause of sudden cardiac death in athletes
Directory of Open Access Journals (Sweden)
Topalović Nikola
2016-01-01
Full Text Available The positive impact of exercise on cardiovascular health is well known. Athletes, who are constantly physically active, are considered to be the healthiest members of our society. That is why their sudden death, during the training or competition, attracts the attention of the general public. Rarely, tragic events of sudden cardiac death (SCD are the reason for questioning if by many positive there are also negative impact of physical exercise. The first case of SCD is recorded as far back as the year 490 BC, when the Greek soldier Pheidippides died after he conveyed news of the great victory of the Greeks over the Persians. Risk of SCD is recognized in the middle of the twentieth century. In our region, discussion about this issue began after the World Basketball Championship, which was held in Ljubljana in 1970, because of the sudden death of the national team member Trajko Rajkovic. One of the important goals of modern sports medicine is to reduce the risk of SCD in athletes to 'inevitable rarity'. Definition of SCD is considered to be any unexpected death due to sudden cardiac arrest. Pedo (Pedoe has divided all causes of SCD in the sport into three categories: Commotio cordis (agitation of the heart, which results from blunt impact to the athletes chest with consequent fatal disorder of heart rhythm; SCD of athletes under the age of 35 because of structural, congenital and inflammatory heart disease, which includes hypertrophic cardiomyopathy as the most important cause of sudden cardiac death, congenital anomalies of the coronary arteries, arrhythmogenic right ventricular cardiomyopathy, myocarditis and other; SCD of athletes older than 35 years which is most common due coronary artery disease - atherosclerosis (the dominant risk in the marathon and half-marathon. .
Spherical Approximation on Unit Sphere
Directory of Open Access Journals (Sweden)
Eman Samir Bhaya
2018-01-01
Full Text Available In this paper we introduce a Jackson type theorem for functions in LP spaces on sphere And study on best approximation of functions in spaces defined on unit sphere. our central problem is to describe the approximation behavior of functions in spaces for by modulus of smoothness of functions.
Approximate circuits for increased reliability
Hamlet, Jason R.; Mayo, Jackson R.
2015-08-18
Embodiments of the invention describe a Boolean circuit having a voter circuit and a plurality of approximate circuits each based, at least in part, on a reference circuit. The approximate circuits are each to generate one or more output signals based on values of received input signals. The voter circuit is to receive the one or more output signals generated by each of the approximate circuits, and is to output one or more signals corresponding to a majority value of the received signals. At least some of the approximate circuits are to generate an output value different than the reference circuit for one or more input signal values; however, for each possible input signal value, the majority values of the one or more output signals generated by the approximate circuits and received by the voter circuit correspond to output signal result values of the reference circuit.
Approximate Dynamic Programming: Combining Regional and Local State Following Approximations.
Deptula, Patryk; Rosenfeld, Joel A; Kamalapurkar, Rushikesh; Dixon, Warren E
2018-06-01
An infinite-horizon optimal regulation problem for a control-affine deterministic system is solved online using a local state following (StaF) kernel and a regional model-based reinforcement learning (R-MBRL) method to approximate the value function. Unlike traditional methods such as R-MBRL that aim to approximate the value function over a large compact set, the StaF kernel approach aims to approximate the value function in a local neighborhood of the state that travels within a compact set. In this paper, the value function is approximated using a state-dependent convex combination of the StaF-based and the R-MBRL-based approximations. As the state enters a neighborhood containing the origin, the value function transitions from being approximated by the StaF approach to the R-MBRL approach. Semiglobal uniformly ultimately bounded (SGUUB) convergence of the system states to the origin is established using a Lyapunov-based analysis. Simulation results are provided for two, three, six, and ten-state dynamical systems to demonstrate the scalability and performance of the developed method.
Doumlele, Kyra; Friedman, Daniel; Buchhalter, Jeffrey; Donner, Elizabeth J; Louik, Jay; Devinsky, Orrin
2017-06-01
generalized tonic-clonic seizures and approximately 30 suspected generalized tonic-clonic seizures. Sudden unexpected death in epilepsy is a very rare outcome in BECTS that clinicians should consider discussing in appropriate circumstances and possibly factoring into treatment decisions.
The efficiency of Flory approximation
International Nuclear Information System (INIS)
Obukhov, S.P.
1984-01-01
The Flory approximation for the self-avoiding chain problem is compared with a conventional perturbation theory expansion. While in perturbation theory each term is averaged over the unperturbed set of configurations, the Flory approximation is equivalent to the perturbation theory with the averaging over the stretched set of configurations. This imposes restrictions on the integration domain in higher order terms and they can be treated self-consistently. The accuracy δν/ν of Flory approximation for self-avoiding chain problems is estimated to be 2-5% for 1 < d < 4. (orig.)
Approximate Implicitization Using Linear Algebra
Directory of Open Access Journals (Sweden)
Oliver J. D. Barrowclough
2012-01-01
Full Text Available We consider a family of algorithms for approximate implicitization of rational parametric curves and surfaces. The main approximation tool in all of the approaches is the singular value decomposition, and they are therefore well suited to floating-point implementation in computer-aided geometric design (CAGD systems. We unify the approaches under the names of commonly known polynomial basis functions and consider various theoretical and practical aspects of the algorithms. We offer new methods for a least squares approach to approximate implicitization using orthogonal polynomials, which tend to be faster and more numerically stable than some existing algorithms. We propose several simple propositions relating the properties of the polynomial bases to their implicit approximation properties.
Rollout sampling approximate policy iteration
Dimitrakakis, C.; Lagoudakis, M.G.
2008-01-01
Several researchers have recently investigated the connection between reinforcement learning and classification. We are motivated by proposals of approximate policy iteration schemes without value functions, which focus on policy representation using classifiers and address policy learning as a
Weighted approximation with varying weight
Totik, Vilmos
1994-01-01
A new construction is given for approximating a logarithmic potential by a discrete one. This yields a new approach to approximation with weighted polynomials of the form w"n"(" "= uppercase)P"n"(" "= uppercase). The new technique settles several open problems, and it leads to a simple proof for the strong asymptotics on some L p(uppercase) extremal problems on the real line with exponential weights, which, for the case p=2, are equivalent to power- type asymptotics for the leading coefficients of the corresponding orthogonal polynomials. The method is also modified toyield (in a sense) uniformly good approximation on the whole support. This allows one to deduce strong asymptotics in some L p(uppercase) extremal problems with varying weights. Applications are given, relating to fast decreasing polynomials, asymptotic behavior of orthogonal polynomials and multipoint Pade approximation. The approach is potential-theoretic, but the text is self-contained.
Framework for sequential approximate optimization
Jacobs, J.H.; Etman, L.F.P.; Keulen, van F.; Rooda, J.E.
2004-01-01
An object-oriented framework for Sequential Approximate Optimization (SAO) isproposed. The framework aims to provide an open environment for thespecification and implementation of SAO strategies. The framework is based onthe Python programming language and contains a toolbox of Python
Sudden acquired retinal degeneration syndrome in western Canada: 93 cases.
Leis, Marina L; Lucyshyn, Danica; Bauer, Bianca S; Grahn, Bruce H; Sandmeyer, Lynne S
2017-11-01
This study reviewed clinical data from dogs diagnosed with sudden acquired retinal degeneration syndrome (SARDS) in western Canada. Medical records from the Western College of Veterinary Medicine from 2002 to 2016 showed that 93 cases of SARDS were diagnosed based on presentation for sudden blindness and a bilaterally extinguished electroretinogram. The most common pure breeds were the miniature schnauzer, dachshund, and pug. The mean age at diagnosis was 8.1 years and males and females were equally affected. Most of the dogs were presented with normal non-chromatic, but abnormal chromatic pupillary light reflexes. The incidence of retinal degeneration as detected via ophthalmoscopy increased over time after SARDS diagnosis. Polyuria, polydipsia, polyphagia, weight gain, elevated liver enzyme values, isosthenuria, and proteinuria were common clinical and laboratory findings. Chromatic pupillary light reflex testing may be more valuable than non-chromatic pupillary light testing in detecting pupil response abnormalities in dogs with SARDS, although electroretinography remains the definitive diagnostic test.
Cryotherapy does not affect peroneal reaction following sudden inversion.
Berg, Christine L; Hart, Joseph M; Palmieri-Smith, Riann; Cross, Kevin M; Ingersoll, Christopher D
2007-11-01
If ankle joint cryotherapy impairs the ability of the ankle musculature to counteract potentially injurious forces, the ankle is left vulnerable to injury. To compare peroneal reaction to sudden inversion following ankle joint cryotherapy. Repeated measures design with independent variables, treatment (cryotherapy and control), and time (baseline, immediately post treatment, 15 minutes post treatment, and 30 minutes post treatment). University research laboratory. Twenty-seven healthy volunteers. An ice bag was secured to the lateral ankle joint for 20 minutes. The onset and average root mean square amplitude of EMG activity in the peroneal muscles was calculated following the release of a trap door mechanism causing inversion. There was no statistically significant change from baseline for peroneal reaction time or average peroneal muscle activity at any post treatment time. Cryotherapy does not affect peroneal muscle reaction following sudden inversion perturbation.
Medico legal investigations into sudden sniffing deaths linked with trichloroethylene.
Da Broi, Ugo; Colatutto, Antonio; Sala, Pierguido; Desinan, Lorenzo
2015-08-01
Sudden deaths attributed to sniffing trichloroethylene are caused by the abuse of this solvent which produces pleasant inebriating effects with rapid dissipation. In the event of repeated cycles of inhalation, a dangerous and uncontrolled systemic accumulation of trichloroethylene may occur, followed by central nervous system depression, coma and lethal cardiorespiratory arrest. Sometimes death occurs outside the hospital environment, without medical intervention or witnesses and without specific necroscopic signs. Medico legal investigations into sudden sniffing deaths associated with trichloroethylene demand careful analysis of the death scene and related circumstances, a detailed understanding of the deceased's medical history and background of substance abuse and an accurate evaluation of all autopsy and laboratory data, with close cooperation between the judiciary, coroners and toxicologists. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
Sudden acquired retinal degeneration syndrome in western Canada: 93 cases
Leis, Marina L.; Lucyshyn, Danica; Bauer, Bianca S.; Grahn, Bruce H.; Sandmeyer, Lynne S.
2017-01-01
This study reviewed clinical data from dogs diagnosed with sudden acquired retinal degeneration syndrome (SARDS) in western Canada. Medical records from the Western College of Veterinary Medicine from 2002 to 2016 showed that 93 cases of SARDS were diagnosed based on presentation for sudden blindness and a bilaterally extinguished electroretinogram. The most common pure breeds were the miniature schnauzer, dachshund, and pug. The mean age at diagnosis was 8.1 years and males and females were equally affected. Most of the dogs were presented with normal non-chromatic, but abnormal chromatic pupillary light reflexes. The incidence of retinal degeneration as detected via ophthalmoscopy increased over time after SARDS diagnosis. Polyuria, polydipsia, polyphagia, weight gain, elevated liver enzyme values, isosthenuria, and proteinuria were common clinical and laboratory findings. Chromatic pupillary light reflex testing may be more valuable than non-chromatic pupillary light testing in detecting pupil response abnormalities in dogs with SARDS, although electroretinography remains the definitive diagnostic test. PMID:29089658
Familial Atrial Septal Defect and Sudden Cardiac Death
DEFF Research Database (Denmark)
Ellesøe, Sabrina Gade; Johansen, Morten Munk; Bjerre, Jesper Vandborg
2016-01-01
OBJECTIVE: Atrial septal defect (ASD) is the second most common congenital heart defect (CHD) and is observed in families as an autosomal dominant trait as well as in nonfamilial CHD. Mutations in the NKX2-5 gene, located on chromosome 5, are associated with ASD, often combined with conduction...... disturbances, cardiomyopathies, complex CHD, and sudden cardiac death as well. Here, we show that NKX2-5 mutations primarily occur in ASD patients with conduction disturbances and heritable ASD. Furthermore, these families are at increased risk of sudden cardiac death. RESULTS: We screened 39 probands...... with familial CHD for mutations in NKX2-5 and discovered a novel mutation in one family (2.5%) with ASD and atrioventricular block. A review of the literature revealed 59 different NKX2-5 mutations in 202 patients. Mutations were significantly more common in familial cases compared to nonfamilial cases (P = 7...
Sudden infant death syndrome: an unrecognized killer in developing countries
Directory of Open Access Journals (Sweden)
Ndu IK
2016-02-01
Full Text Available Ikenna Kingsley Ndu Department of Paediatrics, Enugu State University Teaching Hospital, Enugu, Nigeria Abstract: Sudden infant death syndrome (SIDS is defined as the sudden unexpected death of an infant <1 year of age, with onset of the fatal episode apparently occurring during sleep, that remains unexplained after a thorough investigation including performance of a complete autopsy and review of the circumstances of death and the clinical history. SIDS contributes to infant mortality and resulted in ~15,000 deaths globally in 2013. Most of the risk factors of SIDS are common in developing countries; yet, there has been little interest in SIDS by researchers in Africa. This review looks at the extent of the attention given to SIDS in a developing country like Nigeria, and factors responsible for the scarce data concerning this significant cause of mortality. Keywords: SIDS, mortality, Nigeria
Sickle cell trait and sudden death--bringing it home.
Mitchell, Bruce L.
2007-01-01
Sickle cell trait continues to be the leading cause of sudden death for young African Americans in military basic training and civilian organized sports. The syndrome may have caused the death of up to 10 college football players since 1974 and, as recently as 2000, was suspected as the cause of death of three U.S. Army recruits. The penal military-style boot camps in the United States and the recent death of two teenagers with sickle cell trait merits renewed vigor in the education of athletic instructors, the military and the public about conditions associated with sudden death in individuals with sickle cell trait. Images Figure 1 Figure 2 PMID:17393956
Statistical inferences for bearings life using sudden death test
Directory of Open Access Journals (Sweden)
Morariu Cristin-Olimpiu
2017-01-01
Full Text Available In this paper we propose a calculus method for reliability indicators estimation and a complete statistical inferences for three parameters Weibull distribution of bearings life. Using experimental values regarding the durability of bearings tested on stands by the sudden death tests involves a series of particularities of the estimation using maximum likelihood method and statistical inference accomplishment. The paper detailing these features and also provides an example calculation.
A vortex dynamics perspective on stratospheric sudden warmings
Matthewman, N. J.
2009-01-01
A vortex dynamics approach is used to study the underlying mechanisms leading to polar vortex breakdown during stratospheric sudden warmings (SSWs). Observational data are used in chapter 2 to construct climatologies of the Arctic polar vortex structure during vortex-splitting and vortex-displacement SSWs occurring between 1958 and 2002. During vortex-splitting SSWs, polar vortex breakdown is shown to be typically independent of height (barotropic), whereas breakdown during vor...
Electromagnetic mode conversion: understanding waves that suddenly change their nature
International Nuclear Information System (INIS)
Batchelor, D B; Berry, L A; Bonoli, P T; Carter, M D; Choi, M; D'Azevedo, E; D'Ippolito, D A; Gorelenkov, N; Harvey, R W; Jaeger, E F; Myra, J R; Okuda, H; Phillips, C K; Smithe, D N; Wright, J C
2005-01-01
In a magnetized plasma, such as in fusion devices or the Earth's magnetosphere, several different kinds of waves can simultaneously exist, having very different physical properties. Under the right conditions one wave can quite suddenly convert to another type. Depending on the case, this can be either a great benefit or a problem for the use of waves to heat and control fusion plasmas. Understanding and accurately modeling such behavior is a major computational challenge
Research on a Sudden Explosion and its Environmental Impact
Ye, Maosheng; Ma, Hui; Ni, Qingwei
2017-12-01
A sudden blast was chosen as the studied topic. Also, one computer based virtual experimentation was used to estimate the dimensional impact of initial pollutant plume from blasts. Self-made method using Mathcad code was used to generate the output for the period of the first tenth of a second (1deci-second) to 1minute (60s) of the blast at the point source. It also depicted long-range air pollution travel within the first 1 to 10 minutes. In the case study, it assumed an average directional diffusivity of 1720 m2s-1 which is about 25 per cent of the average generated speed of common explosives. The newly developed model revealed a plume cloud impact of 6.8×107µgm-3 in the first 1millisecond (0.01s) which decayed suddenly to a value of 1.7×107µgm-3 in the first 1decisecond (0.1s). The impact concentration at the point source by the end of the first second (1.0s) was 3.2×105µgm-3 which implied a 99.5% sudden decay when compared to 0.01s concentration value at the emission point source. Computerized experiments observed that air pollutants release from explosives/blasts were dispersed into the atmosphere in the first few seconds by forceful injection instead of by gradual dispersion as is the case with normal air pollutants plume releases.
Sudden unexpected death due to Graves' disease during physical altercation.
Wei, Dengming; Yuan, Xiaogang; Yang, Tiantong; Chang, Lin; Zhang, Xiang; Burke, Allen; Fowler, David; Li, Ling
2013-09-01
We report a case of a 30-year-old woman who suddenly collapsed after having a physical altercation with her husband. Despite immediate resuscitation, she died on arrival at the hospital. The victim's parents requested an autopsy because they believed that their daughter was killed by her husband. Postmortem examination revealed that the victim had a diffusely enlarged thyroid gland and cardiomegaly with left ventricular hypertrophy. There was no evidence of significant trauma on the body. Further postmortem thyroid function tests and review of her medical history indicated that her death was due to Graves' disease. To the best of our knowledge, this is the first case reported of sudden death due to cardiac arrhythmia from Graves' disease induced by physical and emotional stress associated with the criminal activity of another person. The autopsy findings are described. In addition, the literature is reviewed and the significance of postmortem evaluation of thyroid hormones in the cases of sudden death is discussed. © 2013 American Academy of Forensic Sciences.
[Idiopathic sudden deafness: a report of 96 patients].
Gabanou, F; Bera, G; Vincent, C
2012-01-01
Evaluation of the management of idiopathic sudden deafness indicating the usefulness of biological assessments and the pronostic factors of hearing recovery. This is a retrospective study of 96 patients with idiopathic sudden deafness referred to a tertiary centre between 2005 and 2009 treated with corticosteroids intravenously at a daily dose of 1 mg/kg. Mean tonal thresholds were assessed (PTA = [500 Hz + 1000 Hz + 2000 Hz + 4000 Hz]/4). Each audiogram was classified as five classes according to its frequency profile. The hearing recovery is significant between D0-D5 and D5-M1 for the frequencies 0.5, 1 and 2 kHz. For 4 kHz, the recovery is significant between 0 and J5. There is no statistically significant correlation between the presence of associated signs (tinnitus, vertigo) and hearing recovery. Hearing recovery according to the five types of audiograms has the same evolution in the follow-up time but with audiograms type E (cophosis or subcophosis) often associated with an hyporeactivity at the videonystagmography. The presence of cardiovascular disease is a predictor of poor hearing recovery. The usefullness of systematic extensive blood tests is low. In sudden deafness, the maximum hearing recovery takes place in the month following the onset of symptoms. The predictors of poor hearing recovery are an initial mean threshold > 70 dB, the existence of an associated cardiovascular disease.
Cardiac Channelopathies and Sudden Death: Recent Clinical and Genetic Advances.
Fernández-Falgueras, Anna; Sarquella-Brugada, Georgia; Brugada, Josep; Brugada, Ramon; Campuzano, Oscar
2017-01-29
Sudden cardiac death poses a unique challenge to clinicians because it may be the only symptom of an inherited heart condition. Indeed, inherited heart diseases can cause sudden cardiac death in older and younger individuals. Two groups of familial diseases are responsible for sudden cardiac death: cardiomyopathies (mainly hypertrophic cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic cardiomyopathy) and channelopathies (mainly long QT syndrome, Brugada syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). This review focuses on cardiac channelopathies, which are characterized by lethal arrhythmias in the structurally normal heart, incomplete penetrance, and variable expressivity. Arrhythmias in these diseases result from pathogenic variants in genes encoding cardiac ion channels or associated proteins. Due to a lack of gross structural changes in the heart, channelopathies are often considered as potential causes of death in otherwise unexplained forensic autopsies. The asymptomatic nature of channelopathies is cause for concern in family members who may be carrying genetic risk factors, making the identification of these genetic factors of significant clinical importance.
Sudden cardiac death in children (1-18 years)
DEFF Research Database (Denmark)
Winkel, Bo Gregers; Risgaard, Bjarke; Sadjadieh, Golnaz
2014-01-01
AIMS: Hitherto, sudden cardiac death in children (SCDc)-defined as sudden cardiac death (SCD) in the 1-18 years old-has been incompletely described in the general population. Knowledge on incidence rates, causes of death and symptoms prior to death is sparse and has been affected by reporting...... and referral bias. METHODS AND RESULTS: In a nationwide setting all deaths in children aged 1-18 years in Denmark in 2000-06 were included. To chart causes of death and incidence rates, death certificates and autopsy reports were collected and read. By additional use of the extensive healthcare registries...... in Denmark, we were also able to investigate prior disease and symptoms. During the 7-year study period there was an average of 1.11 million persons aged 1-18 years. There were a total of 1504 deaths (214 deaths per year) from 7.78 million person-years. A total of 114 (7.5%) were sudden and unexpected...
Nuclear Hartree-Fock approximation testing and other related approximations
International Nuclear Information System (INIS)
Cohenca, J.M.
1970-01-01
Hartree-Fock, and Tamm-Dancoff approximations are tested for angular momentum of even-even nuclei. Wave functions, energy levels and momenta are comparatively evaluated. Quadripole interactions are studied following the Elliott model. Results are applied to Ne 20 [pt
Shearlets and Optimally Sparse Approximations
DEFF Research Database (Denmark)
Kutyniok, Gitta; Lemvig, Jakob; Lim, Wang-Q
2012-01-01
Multivariate functions are typically governed by anisotropic features such as edges in images or shock fronts in solutions of transport-dominated equations. One major goal both for the purpose of compression as well as for an efficient analysis is the provision of optimally sparse approximations...... optimally sparse approximations of this model class in 2D as well as 3D. Even more, in contrast to all other directional representation systems, a theory for compactly supported shearlet frames was derived which moreover also satisfy this optimality benchmark. This chapter shall serve as an introduction...... to and a survey about sparse approximations of cartoon-like images by band-limited and also compactly supported shearlet frames as well as a reference for the state-of-the-art of this research field....
Diophantine approximation and Dirichlet series
Queffélec, Hervé
2013-01-01
This self-contained book will benefit beginners as well as researchers. It is devoted to Diophantine approximation, the analytic theory of Dirichlet series, and some connections between these two domains, which often occur through the Kronecker approximation theorem. Accordingly, the book is divided into seven chapters, the first three of which present tools from commutative harmonic analysis, including a sharp form of the uncertainty principle, ergodic theory and Diophantine approximation to be used in the sequel. A presentation of continued fraction expansions, including the mixing property of the Gauss map, is given. Chapters four and five present the general theory of Dirichlet series, with classes of examples connected to continued fractions, the famous Bohr point of view, and then the use of random Dirichlet series to produce non-trivial extremal examples, including sharp forms of the Bohnenblust-Hille theorem. Chapter six deals with Hardy-Dirichlet spaces, which are new and useful Banach spaces of anal...
Approximations to camera sensor noise
Jin, Xiaodan; Hirakawa, Keigo
2013-02-01
Noise is present in all image sensor data. Poisson distribution is said to model the stochastic nature of the photon arrival process, while it is common to approximate readout/thermal noise by additive white Gaussian noise (AWGN). Other sources of signal-dependent noise such as Fano and quantization also contribute to the overall noise profile. Question remains, however, about how best to model the combined sensor noise. Though additive Gaussian noise with signal-dependent noise variance (SD-AWGN) and Poisson corruption are two widely used models to approximate the actual sensor noise distribution, the justification given to these types of models are based on limited evidence. The goal of this paper is to provide a more comprehensive characterization of random noise. We concluded by presenting concrete evidence that Poisson model is a better approximation to real camera model than SD-AWGN. We suggest further modification to Poisson that may improve the noise model.
Rational approximations for tomographic reconstructions
International Nuclear Information System (INIS)
Reynolds, Matthew; Beylkin, Gregory; Monzón, Lucas
2013-01-01
We use optimal rational approximations of projection data collected in x-ray tomography to improve image resolution. Under the assumption that the object of interest is described by functions with jump discontinuities, for each projection we construct its rational approximation with a small (near optimal) number of terms for a given accuracy threshold. This allows us to augment the measured data, i.e., double the number of available samples in each projection or, equivalently, extend (double) the domain of their Fourier transform. We also develop a new, fast, polar coordinate Fourier domain algorithm which uses our nonlinear approximation of projection data in a natural way. Using augmented projections of the Shepp–Logan phantom, we provide a comparison between the new algorithm and the standard filtered back-projection algorithm. We demonstrate that the reconstructed image has improved resolution without additional artifacts near sharp transitions in the image. (paper)
Approximation methods in probability theory
Čekanavičius, Vydas
2016-01-01
This book presents a wide range of well-known and less common methods used for estimating the accuracy of probabilistic approximations, including the Esseen type inversion formulas, the Stein method as well as the methods of convolutions and triangle function. Emphasising the correct usage of the methods presented, each step required for the proofs is examined in detail. As a result, this textbook provides valuable tools for proving approximation theorems. While Approximation Methods in Probability Theory will appeal to everyone interested in limit theorems of probability theory, the book is particularly aimed at graduate students who have completed a standard intermediate course in probability theory. Furthermore, experienced researchers wanting to enlarge their toolkit will also find this book useful.
Approximate reasoning in physical systems
International Nuclear Information System (INIS)
Mutihac, R.
1991-01-01
The theory of fuzzy sets provides excellent ground to deal with fuzzy observations (uncertain or imprecise signals, wavelengths, temperatures,etc.) fuzzy functions (spectra and depth profiles) and fuzzy logic and approximate reasoning. First, the basic ideas of fuzzy set theory are briefly presented. Secondly, stress is put on application of simple fuzzy set operations for matching candidate reference spectra of a spectral library to an unknown sample spectrum (e.g. IR spectroscopy). Thirdly, approximate reasoning is applied to infer an unknown property from information available in a database (e.g. crystal systems). Finally, multi-dimensional fuzzy reasoning techniques are suggested. (Author)
Face Recognition using Approximate Arithmetic
DEFF Research Database (Denmark)
Marso, Karol
Face recognition is image processing technique which aims to identify human faces and found its use in various diﬀerent ﬁelds for example in security. Throughout the years this ﬁeld evolved and there are many approaches and many diﬀerent algorithms which aim to make the face recognition as eﬀective...... processing applications the results do not need to be completely precise and use of the approximate arithmetic can lead to reduction in terms of delay, space and power consumption. In this paper we examine possible use of approximate arithmetic in face recognition using Eigenfaces algorithm....
De Wachter, Stefan; Wyndaele, Jean-Jacques
2008-04-01
To evaluate whether a compelling desire to void (CDV) is always perceived suddenly, or whether it can result from the gradual build-up of bladder-filling sensations. The pattern of filling sensations was evaluated during standard cystometric bladder filling in 75 patients who complained of urgency and showed detrusor overactivity during cystometry. Cystometric filling ended when a CDV was reported. The 'warning volume' is defined as the difference in volume between the first perception of filling and the volume at CDV. Different patterns of bladder-filling sensations were reported. A CDV occurred suddenly, without a preceding sensation in 13% of the patients, whereas 66% reported at least two normal preceding filling sensations before a CDV. The bladder volume at the CDV was significantly smaller in patients that reported no or just one preceding sensation compared with those that reported the normal pattern of two or three sensations (P perception was reported was not different regardless of whether it was described as a first sensation of filling, a first desire or a CDV (P = 0.42). The warning volumes were not different between patients with one or no standardized filling sensations (P = 0.7), but they were significantly smaller than in patients with two or three filling sensations (P = 0.85). A CDV can occur suddenly if normal filling sensation is disturbed, but also gradually if normal filling sensation is preserved. In cases of disturbed filling sensation, the volume at CDV and the warning volume are significantly lower.
Sudden gains in group cognitive-behavioral therapy for panic disorder.
Clerkin, Elise M; Teachman, Bethany A; Smith-Janik, Shannan B
2008-11-01
The current study investigates sudden gains (rapid symptom reduction) in group cognitive-behavioral therapy for panic disorder. Sudden gains occurring after session 2 of treatment predicted overall symptom reduction at treatment termination and some changes in cognitive biases. Meanwhile, sudden gains occurring immediately following session 1 were not associated with symptom reduction or cognitive change. Together, this research points to the importance of examining sudden gains across the entire span of treatment, as well as the potential role of sudden gains in recovery from panic disorder.
Approximate Reanalysis in Topology Optimization
DEFF Research Database (Denmark)
Amir, Oded; Bendsøe, Martin P.; Sigmund, Ole
2009-01-01
In the nested approach to structural optimization, most of the computational effort is invested in the solution of the finite element analysis equations. In this study, the integration of an approximate reanalysis procedure into the framework of topology optimization of continuum structures...
Approximate Matching of Hierarchial Data
DEFF Research Database (Denmark)
Augsten, Nikolaus
-grams of a tree are all its subtrees of a particular shape. Intuitively, two trees are similar if they have many pq-grams in common. The pq-gram distance is an efficient and effective approximation of the tree edit distance. We analyze the properties of the pq-gram distance and compare it with the tree edit...
Approximation of Surfaces by Cylinders
DEFF Research Database (Denmark)
Randrup, Thomas
1998-01-01
We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...
Approximation properties of haplotype tagging
Directory of Open Access Journals (Sweden)
Dreiseitl Stephan
2006-01-01
Full Text Available Abstract Background Single nucleotide polymorphisms (SNPs are locations at which the genomic sequences of population members differ. Since these differences are known to follow patterns, disease association studies are facilitated by identifying SNPs that allow the unique identification of such patterns. This process, known as haplotype tagging, is formulated as a combinatorial optimization problem and analyzed in terms of complexity and approximation properties. Results It is shown that the tagging problem is NP-hard but approximable within 1 + ln((n2 - n/2 for n haplotypes but not approximable within (1 - ε ln(n/2 for any ε > 0 unless NP ⊂ DTIME(nlog log n. A simple, very easily implementable algorithm that exhibits the above upper bound on solution quality is presented. This algorithm has running time O((2m - p + 1 ≤ O(m(n2 - n/2 where p ≤ min(n, m for n haplotypes of size m. As we show that the approximation bound is asymptotically tight, the algorithm presented is optimal with respect to this asymptotic bound. Conclusion The haplotype tagging problem is hard, but approachable with a fast, practical, and surprisingly simple algorithm that cannot be significantly improved upon on a single processor machine. Hence, significant improvement in computatational efforts expended can only be expected if the computational effort is distributed and done in parallel.
All-Norm Approximation Algorithms
Azar, Yossi; Epstein, Leah; Richter, Yossi; Woeginger, Gerhard J.; Penttonen, Martti; Meineche Schmidt, Erik
2002-01-01
A major drawback in optimization problems and in particular in scheduling problems is that for every measure there may be a different optimal solution. In many cases the various measures are different ℓ p norms. We address this problem by introducing the concept of an All-norm ρ-approximation
Truthful approximations to range voting
DEFF Research Database (Denmark)
Filos-Ratsika, Aris; Miltersen, Peter Bro
We consider the fundamental mechanism design problem of approximate social welfare maximization under general cardinal preferences on a finite number of alternatives and without money. The well-known range voting scheme can be thought of as a non-truthful mechanism for exact social welfare...
On badly approximable complex numbers
DEFF Research Database (Denmark)
Esdahl-Schou, Rune; Kristensen, S.
We show that the set of complex numbers which are badly approximable by ratios of elements of , where has maximal Hausdorff dimension. In addition, the intersection of these sets is shown to have maximal dimension. The results remain true when the sets in question are intersected with a suitably...
Approximate reasoning in decision analysis
Energy Technology Data Exchange (ETDEWEB)
Gupta, M M; Sanchez, E
1982-01-01
The volume aims to incorporate the recent advances in both theory and applications. It contains 44 articles by 74 contributors from 17 different countries. The topics considered include: membership functions; composite fuzzy relations; fuzzy logic and inference; classifications and similarity measures; expert systems and medical diagnosis; psychological measurements and human behaviour; approximate reasoning and decision analysis; and fuzzy clustering algorithms.
Rational approximation of vertical segments
Salazar Celis, Oliver; Cuyt, Annie; Verdonk, Brigitte
2007-08-01
In many applications, observations are prone to imprecise measurements. When constructing a model based on such data, an approximation rather than an interpolation approach is needed. Very often a least squares approximation is used. Here we follow a different approach. A natural way for dealing with uncertainty in the data is by means of an uncertainty interval. We assume that the uncertainty in the independent variables is negligible and that for each observation an uncertainty interval can be given which contains the (unknown) exact value. To approximate such data we look for functions which intersect all uncertainty intervals. In the past this problem has been studied for polynomials, or more generally for functions which are linear in the unknown coefficients. Here we study the problem for a particular class of functions which are nonlinear in the unknown coefficients, namely rational functions. We show how to reduce the problem to a quadratic programming problem with a strictly convex objective function, yielding a unique rational function which intersects all uncertainty intervals and satisfies some additional properties. Compared to rational least squares approximation which reduces to a nonlinear optimization problem where the objective function may have many local minima, this makes the new approach attractive.
Pythagorean Approximations and Continued Fractions
Peralta, Javier
2008-01-01
In this article, we will show that the Pythagorean approximations of [the square root of] 2 coincide with those achieved in the 16th century by means of continued fractions. Assuming this fact and the known relation that connects the Fibonacci sequence with the golden section, we shall establish a procedure to obtain sequences of rational numbers…
Ultrafast Approximation for Phylogenetic Bootstrap
Bui Quang Minh, [No Value; Nguyen, Thi; von Haeseler, Arndt
Nonparametric bootstrap has been a widely used tool in phylogenetic analysis to assess the clade support of phylogenetic trees. However, with the rapidly growing amount of data, this task remains a computational bottleneck. Recently, approximation methods such as the RAxML rapid bootstrap (RBS) and
Reporting a sudden death due to accidental gasoline inhalation.
Martínez, María Antonia; Ballesteros, Salomé; Alcaraz, Rafael
2012-02-10
The investigation of uncertain fatalities requires accurate determination of the cause of death, with assessment of all factors that may have contributed to it. Gasoline is a complex and highly variable mixture of aliphatic and aromatic hydrocarbons that can lead to cardiac arrhythmias due to sensitization of the myocardium to catecholamines or acts as a simple asphyxiant if the vapors displace sufficient oxygen from the breathing atmosphere. This work describes a sudden occupational fatality involving gasoline. The importance of this petroleum distillate detection and its quantitative toxicological significance is discussed using a validated analytical method. A 51 year-old Caucasian healthy man without significant medical history was supervising the repairs of the telephone lines in a manhole near to a gas station. He died suddenly after inhaling gasoline vapors from an accidental leak. Extensive blistering and peeling of skin were observed on the skin of the face, neck, anterior chest, upper and lower extremities, and back. The internal examination showed a strong odor of gasoline, specially detected in the respiratory tract. The toxicological screening and quantitation of gasoline was performed by means of gas chromatography with flame ionization detector and confirmation was performed using gas chromatography-mass spectrometry. Disposition of gasoline in different tissues was as follows: heart blood, 35.7 mg/L; urine, not detected; vitreous humor, 1.9 mg/L; liver, 194.7 mg/kg; lung, 147.6 mg/kg; and gastric content, 116,6 mg/L (2.7 mg total). Based upon the toxicological data along with the autopsy findings, the cause of death was determined to be gasoline poisoning and the manner of death was accidental. We would like to alert on the importance of testing for gasoline, and in general for volatile hydrocarbons, in work-related sudden deaths involving inhalation of hydrocarbon vapors and/or exhaust fumes. Copyright © 2011 Elsevier Ireland Ltd. All rights
Coupled catastrophes: sudden shifts cascade and hop among interdependent systems
Barnett, George; D'Souza, Raissa M.
2015-01-01
An important challenge in several disciplines is to understand how sudden changes can propagate among coupled systems. Examples include the synchronization of business cycles, population collapse in patchy ecosystems, markets shifting to a new technology platform, collapses in prices and in confidence in financial markets, and protests erupting in multiple countries. A number of mathematical models of these phenomena have multiple equilibria separated by saddle-node bifurcations. We study this behaviour in its normal form as fast–slow ordinary differential equations. In our model, a system consists of multiple subsystems, such as countries in the global economy or patches of an ecosystem. Each subsystem is described by a scalar quantity, such as economic output or population, that undergoes sudden changes via saddle-node bifurcations. The subsystems are coupled via their scalar quantity (e.g. trade couples economic output; diffusion couples populations); that coupling moves the locations of their bifurcations. The model demonstrates two ways in which sudden changes can propagate: they can cascade (one causing the next), or they can hop over subsystems. The latter is absent from classic models of cascades. For an application, we study the Arab Spring protests. After connecting the model to sociological theories that have bistability, we use socioeconomic data to estimate relative proximities to tipping points and Facebook data to estimate couplings among countries. We find that although protests tend to spread locally, they also seem to ‘hop' over countries, like in the stylized model; this result highlights a new class of temporal motifs in longitudinal network datasets. PMID:26559684
Sarcomeric gene mutations in sudden infant death syndrome (SIDS).
Brion, Maria; Allegue, Catarina; Santori, Montserrat; Gil, Rocio; Blanco-Verea, Alejandro; Haas, Cordula; Bartsch, Christine; Poster, Simone; Madea, Burkhard; Campuzano, Oscar; Brugada, Ramon; Carracedo, Angel
2012-06-10
In developed countries, sudden infant death syndrome (SIDS) represents the most prevalent cause of death in children between 1 month and 1 year of age. SIDS is a diagnosis of exclusion, a negative autopsy which requires the absence of structural organ disease. Although investigators have confirmed that a significant percentage of SIDS cases are actually channelopathies, no data have been made available as to whether other sudden cardiac death-associated diseases, such as hypertrophic cardiomyopathy (HCM), could be responsible for some cases of SIDS. The presence of a genetic mutation in the sarcomeric protein usually affects the force of contraction of the myocyte, whose weakness is compensated with progressive hypertrophy and disarray. However, it is unclear whether in the most incipient forms, that is, first years of life, the lack of these phenotypes still confers a risk of arrhythmogenesis. The main goal of the present study is to wonder whether genetic defects in the sarcomeric proteins, previously associated with HCM, could be responsible for SIDS. We have analysed 286 SIDS cases for the most common genes implicated in HCM in adults. A total of 680 mutations localised in 16 genes were analysed by semi-automated matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDITOF-MS) using the Sequenom MassARRAY(®) System. Ten subjects with completely normal hearts showed mutated alleles at nine of the genetic variants analysed, and one additional novel mutation was detected by conventional sequencing. Therefore, a genetic mutation associated with HCM may cause sudden cardiac death in the absence of an identifiable phenotype. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Coronary atherosclerosis in sudden cardiac death: An autopsy study
Directory of Open Access Journals (Sweden)
Sudha M
2009-10-01
Full Text Available Background: The incidence of ischemic heart disease (IHD has markedly increased in India over the past few years. Considering the variations in racial, dietary and lifestyle patterns in our population, it is essential to study the biology of coronary atherosclerosis in our patients. Vulnerable plaques have a large number of foam cells, extracellular lipid, thin fibrous caps and clusters of inflammatory cells and are more prone to rupture. These plaques are nourished by the microvessels arising from the vasa vasorum of the blood vessels and by lumen-derived microvessels through the fibrous cap. This autopsy study was designed to analyse the coronary arterial tree in cases of sudden cardiac death, classify coronary atherosclerotic plaques and to assess the factors contributing to vulnerability of the plaques including inflammation, calcification and microvascular density. Materials and Methods: Seven cases of sudden cardiac death were included in the study. The hearts were perfusion-fixed and the coronary arteries along with their main branches were dissected and studied. The location of the plaques, type of plaques, presence of inflammation and calcification were assessed. The cap thickness and microvessel density per 1000um 2 were assessed. The statistical significance was estimated. Results and Conclusions: Extensive high-grade coronary atherosclerotic disease was seen in all sudden cardiac death cases. Majority of the plaques were vulnerable. High-grade inflammation was seen in most of the vulnerable and ruptured plaques. All the ruptured plaques were uncalcified indicating that calcification probably stabilizes the plaques and protects against rupture. Increased microvessel density was noted in ruptured plaques compared to vulnerable plaques. However, it was not statistically significant.
Beyond the random phase approximation
DEFF Research Database (Denmark)
Olsen, Thomas; Thygesen, Kristian S.
2013-01-01
We assess the performance of a recently proposed renormalized adiabatic local density approximation (rALDA) for ab initio calculations of electronic correlation energies in solids and molecules. The method is an extension of the random phase approximation (RPA) derived from time-dependent density...... functional theory and the adiabatic connection fluctuation-dissipation theorem and contains no fitted parameters. The new kernel is shown to preserve the accurate description of dispersive interactions from RPA while significantly improving the description of short-range correlation in molecules, insulators......, and metals. For molecular atomization energies, the rALDA is a factor of 7 better than RPA and a factor of 4 better than the Perdew-Burke-Ernzerhof (PBE) functional when compared to experiments, and a factor of 3 (1.5) better than RPA (PBE) for cohesive energies of solids. For transition metals...
Hydrogen: Beyond the Classic Approximation
International Nuclear Information System (INIS)
Scivetti, Ivan
2003-01-01
The classical nucleus approximation is the most frequently used approach for the resolution of problems in condensed matter physics.However, there are systems in nature where it is necessary to introduce the nuclear degrees of freedom to obtain a correct description of the properties.Examples of this, are the systems with containing hydrogen.In this work, we have studied the resolution of the quantum nuclear problem for the particular case of the water molecule.The Hartree approximation has been used, i.e. we have considered that the nuclei are distinguishable particles.In addition, we have proposed a model to solve the tunneling process, which involves the resolution of the nuclear problem for configurations of the system away from its equilibrium position
G. Liebrechts-Akkerman (Germaine); F. Liu (Fan); O. Lao Grueso (Oscar); A.H.A.G. Ooms (Ariadne ); K. van Duijn (Kate); M. Vermeulen (Mark); V.W.V. Jaddoe (Vincent); A. Hofman (Albert); A.C. Engelberts (Adele); M.H. Kayser (Manfred)
2014-01-01
textabstractUnclassified sudden infant death (USID) is the sudden and unexpected death of an infant that remains unexplained after thorough case investigation including performance of a complete autopsy and review of the circumstances of death and the clinical history. When the infant is below 1
Approximation errors during variance propagation
International Nuclear Information System (INIS)
Dinsmore, Stephen
1986-01-01
Risk and reliability analyses are often performed by constructing and quantifying large fault trees. The inputs to these models are component failure events whose probability of occuring are best represented as random variables. This paper examines the errors inherent in two approximation techniques used to calculate the top event's variance from the inputs' variance. Two sample fault trees are evaluated and several three dimensional plots illustrating the magnitude of the error over a wide range of input means and variances are given
The analysis of Sudden Infant Death Syndrome in Poland
Directory of Open Access Journals (Sweden)
Anna Lewandowska
2017-05-01
Full Text Available Introduction: Sudden Infant Death Syndrome is defined in literature similarly as a sudden and unexpected death of an infant occurring during sleep and, at the same time, causes of which cannot be explained based on anamnesis, circumstances of death or comprehensive post-mortem examinations. Sudden Infant Death Syndrome is considered to be the most frequent cause of death among infants in the developed countries. Incidence of SIDS in the whole world ranges from about 0.1 to 6.0/1,000 live births. As much as 90% concerns deaths in the first year of life of a child, whereas 70% stands for deaths for which the cause remains unknown. In SIDS, about 90% of cases concern children under 1 year old and, in particular, at the age of between 2 and 4 months. The aim: The aim of the study was to present the most significant aspects of SIDS as well as description and analysis of risk factors for occurrence of sudden infant death syndrome based on statistical data. Materials and methods: For the purpose of the study, the secondary data analysis and desk research technique have been applied. The analysis is based on statistical data from the time period 2009-2014 released by the Central Statistical Office of Poland. Results: In 2009-2014, the highest number of deaths of infants and new-borns was reported in 2009 with the number being as high as 2,327. In the following years, the number of deaths of new-borns and infants systematically decreased. In 2010 it was 2,057 and in 2011 – 1,836, in 2012 – 1,791, in 2013 – 1,684, and in 2014 – 1,583. The highest number of deaths of boys was reported in 2009 – 1,298, while the number of deaths of girls in that year, although it was the highest in the analysed period, was lower – 1,029. Conclusions: cases of death were more frequent among boys rather than girls. The highest number of deaths was reported among infants under the age of one month and the number decreased with an increasing infants’ age. More
Nonlinear dynamics, fractals, cardiac physiology and sudden death
Goldberger, Ary L.
1987-01-01
The authors propose a diametrically opposite viewpoint to the generally accepted tendency of equating healthy function with order and disease with chaos. With regard to the question of sudden cardiac death and chaos, it is suggested that certain features of dynamical chaos related to fractal structure and fractal dynamics may be important organizing principles in normal physiology and that certain pathologies, including ventricular fibrillation, represent a class of 'pathological periodicities'. Some laboratory work bearing on the relation of nonlinear analysis to physiological and pathophysiological data is briefly reviewed, with tentative theories and models described in reference to the mechanism of ventricular fibrillation.
Evolution of IPv6 Internet topology with unusual sudden changes
Ai, Jun; Zhao, Hai; Kathleen, M. Carley; Su, Zhan; Li, Hui
2013-07-01
The evolution of Internet topology is not always smooth but sometimes with unusual sudden changes. Consequently, identifying patterns of unusual topology evolution is critical for Internet topology modeling and simulation. We analyze IPv6 Internet topology evolution in IP-level graph to demonstrate how it changes in uncommon ways to restructure the Internet. After evaluating the changes of average degree, average path length, and some other metrics over time, we find that in the case of a large-scale growing the Internet becomes more robust; whereas in a top—bottom connection enhancement the Internet maintains its efficiency with links largely decreased.
Spinal epidermoid cyst with sudden onset of paraplegia
Directory of Open Access Journals (Sweden)
Munshi Anusheel
2009-01-01
Full Text Available Spinal epidermoid cysts, whether congenital or iatrogenic, are relatively uncommon in the spinal cord. When they occur, the typical location is in the subdural, extramedullary space of the lumbo-sacral region. We describe an unusual presentation in a 3-year-old male child which mimicked astrocytoma clinicoradiologically. The child developed sudden onset of inability in walking and weakness of both lower limbs after a fall. There was a dramatic reversal of symptoms after surgery. Histopathology revealed an epidermoid cyst of the spine. On the first follow-up visit at 3 months, the child was asymptomatic.
Evolution of IPv6 Internet topology with unusual sudden changes
International Nuclear Information System (INIS)
Ai Jun; Su Zhan; Li Hui; Zhao Hai; Carley, Kathleen M.
2013-01-01
The evolution of Internet topology is not always smooth but sometimes with unusual sudden changes. Consequently, identifying patterns of unusual topology evolution is critical for Internet topology modeling and simulation. We analyze IPv6 Internet topology evolution in IP-level graph to demonstrate how it changes in uncommon ways to restructure the Internet. After evaluating the changes of average degree, average path length, and some other metrics over time, we find that in the case of a large-scale growing the Internet becomes more robust; whereas in a top—bottom connection enhancement the Internet maintains its efficiency with links largely decreased
[Hypertensive crisis and sudden change of vision in young patients].
Cortés Fernández, M S; Martín-Castillejos, C; Armario, P
2016-01-01
The sudden change in vision is a medical emergency that must be evaluated immediately to rule out important institutions as systemic vasculitis or ischemic stroke. Its association with hypertensive crisis makes it necessary to rule out accelerated-malignant hypertension, which is accompanied by other retinal disorders (exudates and hemorrhages) and adrenal involvement. Nonarteritic anterior ischemic optic neuropathy (AION) is another entity to consider, as is it not uncommon in the young (12.7% in a series of 848 cases). Its association with hypertension has been described in 32% of cases. Copyright © 2016 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.
Sudden Relaminarization and Lifetimes in Forced Isotropic Turbulence.
Linkmann, Moritz F; Morozov, Alexander
2015-09-25
We demonstrate an unexpected connection between isotropic turbulence and wall-bounded shear flows. We perform direct numerical simulations of isotropic turbulence forced at large scales at moderate Reynolds numbers and observe sudden transitions from a chaotic dynamics to a spatially simple flow, analogous to the laminar state in wall bounded shear flows. We find that the survival probabilities of turbulence are exponential and the typical lifetimes increase superexponentially with the Reynolds number. Our results suggest that both isotropic turbulence and wall-bounded shear flows qualitatively share the same phase-space dynamics.
Sudden death of a child due to respiratory diphtheria.
Swain, Rajanikanta; Behera, Chittaranjan; Arava, Sudheer Kumar; Kundu, Naveen
2016-06-01
A four-year-old girl presented to the emergency department with respiratory distress. Death occurred despite attempted resuscitation. The illness was not clinically diagnosed. Her father revealed that she had a fever and sore throat for the last four days and was not immunised for diphtheria. Characteristic gross and microscopic pathology of respiratory diphtheria and microbiological findings were observed. The cause of death was acute respiratory failure consequent upon upper airway obstruction from diphtheria. Forensic pathologists should remember that the diphtheria cases can cause sudden death especially in developing countries. © The Author(s) 2016.
Unusual causes of sudden anuria in renal transplant patients
International Nuclear Information System (INIS)
Abutaleb, N.; Hamza, A.; Younis, S.; Adem, M.; Obaideen, A.; Zakaria, M.; El-Jubab, A.
2007-01-01
Sudden unexplained anuria in renal transplant patients could well be secondary to occult internal hemorrhage rather than the usual vascular thrombotic or obstructive event, even in the completely stable patient. Urgent intervention in such bleeding states can save patient's life and graft function. Graft survival is very exceptional in graft artery or vein thrombosis. Contrary to hemorrhagic events, life is usually not threatened by thrombotic events involving the renal graft vasculature. We present here three unfortunate cases that shared the problem of unexpected anuria due to a hemorrhagic event in apparently stable renal transplant patients. (author)
WKB approximation in atomic physics
International Nuclear Information System (INIS)
Karnakov, Boris Mikhailovich
2013-01-01
Provides extensive coverage of the Wentzel-Kramers-Brillouin approximation and its applications. Presented as a sequence of problems with highly detailed solutions. Gives a concise introduction for calculating Rydberg states, potential barriers and quasistationary systems. This book has evolved from lectures devoted to applications of the Wentzel-Kramers-Brillouin- (WKB or quasi-classical) approximation and of the method of 1/N -expansion for solving various problems in atomic and nuclear physics. The intent of this book is to help students and investigators in this field to extend their knowledge of these important calculation methods in quantum mechanics. Much material is contained herein that is not to be found elsewhere. WKB approximation, while constituting a fundamental area in atomic physics, has not been the focus of many books. A novel method has been adopted for the presentation of the subject matter, the material is presented as a succession of problems, followed by a detailed way of solving them. The methods introduced are then used to calculate Rydberg states in atomic systems and to evaluate potential barriers and quasistationary states. Finally, adiabatic transition and ionization of quantum systems are covered.
Causes and prevention of sudden cardiac death in the elderly.
Tung, Patricia; Albert, Christine M
2013-03-01
Sudden cardiac death (SCD) is a major cause of mortality in elderly individuals owing to a high prevalence of coronary heart disease, systolic dysfunction, and congestive heart failure (CHF). Although the incidence of SCD increases with age, the proportion of cardiac deaths that are sudden decreases owing to high numbers of other cardiac causes of death in elderly individuals. Implantable cardioverter-defibrillator (ICD) therapy has been demonstrated to improve survival and prevent SCD in selected patients with systolic dysfunction and CHF. However, ICD therapy in elderly patients might not be effective because of a greater rate of pulseless electrical activity underlying SCD and other competing nonarrhythmic causes of death in this population. Although under-represented in randomized trials of ICD use, elderly patients comprise a substantial proportion of the population that qualifies for and receives an ICD for primary prevention under current guidelines. Cardiac resynchronization therapy (CRT), which has been demonstrated to reduce mortality in selected populations with heart failure, is also more commonly used in this group of patients than in younger individuals. In this Review, we examine the causes of SCD in elderly individuals, and discuss the existing evidence for effectiveness of ICD therapy and CRT in this growing population.
Sudden visual loss after cardiac resynchronization therapy device implantation.
De Vitis, Luigi A; Marchese, Alessandro; Giuffrè, Chiara; Carnevali, Adriano; Querques, Lea; Tomasso, Livia; Baldin, Giovanni; Maestranzi, Gisella; Lattanzio, Rosangela; Querques, Giuseppe; Bandello, Francesco
2017-03-10
To report a case of sudden decrease in visual acuity possibly due to a cardiogenic embolism in a patient who underwent cardiac resynchronization therapy (CRT) device implantation. A 62-year-old man with severe left ventricular systolic dysfunction and a left bundle branch block was referred to our department because of a sudden decrease in visual acuity. Nine days earlier, he had undergone cardiac transapical implantation of a CRT device, which was followed, 2 days later, by an inflammatory reaction. The patient underwent several general and ophthalmologic examinations, including multimodal imaging. At presentation, right eye (RE) best-corrected visual acuity (BCVA) was counting fingers and RE pupil was hyporeactive. Fundus examination revealed white-centered hemorrhagic dots suggestive of Roth spots. Fluorescein angiography showed delay in vascular perfusion during early stage, late hyperfluorescence of the macula and optic disk, and peripheral perivascular leakage. The first visual field test showed complete loss of vision RE and a normal left eye. Due to suspected giant cell arteritis, temporal artery biopsy was performed. Thirty minutes after the procedure, an ischemic stroke with right hemisyndrome and aphasia occurred. The RE BCVA worsened to hands motion. Four months later, RE BCVA did not improve, despite improvement in fluorescein angiography inflammatory sign. We report a possible cardiogenic embolism secondary to undiagnosed infective endocarditis causing monocular visual loss after CRT device implantation. It remains unclear how the embolus caused severe functional damage without altering the retinal anatomical structure.
Transformation priming helps to disambiguate sudden changes of sensory inputs.
Pastukhov, Alexander; Vivian-Griffiths, Solveiga; Braun, Jochen
2015-11-01
Retinal input is riddled with abrupt transients due to self-motion, changes in illumination, object-motion, etc. Our visual system must correctly interpret each of these changes to keep visual perception consistent and sensitive. This poses an enormous challenge, as many transients are highly ambiguous in that they are consistent with many alternative physical transformations. Here we investigated inter-trial effects in three situations with sudden and ambiguous transients, each presenting two alternative appearances (rotation-reversing structure-from-motion, polarity-reversing shape-from-shading, and streaming-bouncing object collisions). In every situation, we observed priming of transformations as the outcome perceived in earlier trials tended to repeat in subsequent trials and this repetition was contingent on perceptual experience. The observed priming was specific to transformations and did not originate in priming of perceptual states preceding a transient. Moreover, transformation priming was independent of attention and specific to low level stimulus attributes. In summary, we show how "transformation priors" and experience-driven updating of such priors helps to disambiguate sudden changes of sensory inputs. We discuss how dynamic transformation priors can be instantiated as "transition energies" in an "energy landscape" model of the visual perception. Copyright © 2015 Elsevier Ltd. All rights reserved.
Phenotype-driven molecular autopsy for sudden cardiac death.
Cann, F; Corbett, M; O'Sullivan, D; Tennant, S; Hailey, H; Grieve, J H K; Broadhurst, P; Rankin, R; Dean, J C S
2017-01-01
A phenotype-driven approach to molecular autopsy based in a multidisciplinary team comprising clinical and laboratory genetics, forensic medicine and cardiology is described. Over a 13 year period, molecular autopsy was undertaken in 96 sudden cardiac death cases. A total of 46 cases aged 1-40 years had normal hearts and suspected arrhythmic death. Seven (15%) had likely pathogenic variants in ion channelopathy genes [KCNQ1 (1), KCNH2 (4), SCN5A (1), RyR2(1)]. Fifty cases aged between 2 and 67 had a cardiomyopathy. Twenty-five had arrhythmogenic right ventricular cardiomyopathy (ARVC), 10 dilated cardiomyopathy (DCM) and 15 hypertrophic cardiomyopathy (HCM). Likely pathogenic variants were found in three ARVC cases (12%) in PKP2, DSC2 or DSP, two DCM cases (20%) in MYH7, and four HCM cases (27%) in MYBPC3 (3) or MYH7 (1). Uptake of cascade screening in relatives was higher when a molecular diagnosis was made at autopsy. In three families, variants previously published as pathogenic were detected, but clinical investigation revealed no abnormalities in carrier relatives. With a conservative approach to defining pathogenicity of sequence variants incorporating family phenotype information and population genomic data, a molecular diagnosis was made in 15% of sudden arrhythmic deaths and 18% of cardiomyopathy deaths. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Sudden cardiac death with triple pathologies: A case report
Directory of Open Access Journals (Sweden)
R. Razuin
2017-06-01
Full Text Available Sudden cardiac death in young adults may be associated with rare cardiomyopathies such as left ventricular noncompaction (LVNC and arrhythmogenic right ventricular (ARVC cardiomyopathies. LVNC is characterised by hypertrabeculations and deep recesses of the left ventricle. ARVC presents with thin myocardium as a result of extensive fibro-fatty infiltrations. In both conditions, death may be due to arrhythmia, thromboembolic events or heart failure. We report a case of a 21-year old athletic young man who collapsed at the futsal court right after the game. He was resuscitated but expired at the hospital after a brief admission. A week earlier, he had a similar episode of syncope and revived through cardio-pulmonary resuscitation at the site. Post mortem examination showed extensive acute myocardial infarction (AMI involving the papillary muscles and the left ventricular wall. Features of LVNC were also observed. On top of that, the right ventricle showed patchy thin myocardium as the wall was largely comprised of fat. Histology examination confirmed the presence of AMI and massive fibro-fatty infiltrations of the right ventricle. This unfortunate young man had co-existing cardiomyopathies which is rare indeed. As he succumbed to AMI, this mechanism of death is also uncommonly associated with neither LVNC nor ARVC. In conclusion, young and physically active individuals may not be spared of sudden cardiac death. Mild and non-specific symptoms should not be taken lightly as it may be the subtle signs of cardiomyopathies.
Brugada Syndrome: Are we doing enough to prevent sudden death?
International Nuclear Information System (INIS)
Buksh, Jahangir A.; Al-Hersi, Ahmad S.; Al-Nozha, Mansour M.
2007-01-01
Burgada syndrome (BS) is an inherited arrythmogenic disease characterized by typical ECG changes in the form of an SR pattern in VI to V2, and ST segment elevation in VI to V3 and prolongation of the QT interval in right precordial leads. This syndrome carries an increased risk of sudden death due to arrhythmias. This disease was first described in 1992 by Joseph Brugada et al and was named Brugada syndrome by Yan and Antzelvich in 1996. By 2003 more than 600 patients had been reported by Brugada et al and hundreds by others. A genetic aspect to BS is now recognized and been linked to the alpha subunit of the cardiac sodium channel gene SCN5A. Over five dozen mutations in SCN5A have been identified. Accentuation of the right ventricular notch under pathophysiological conditions leads to exaggeration of the J-wave or J-point elevation and a saddle-shaped configuration of the repolarisation waves. Diagnosis is essentially by electrocardiogram either by spontaneous changes or by provocation by sodium channel blockers drugs, e.g., procainamide, flecainide. The role of electrophysiological studies in induction of arrhythmia in asymptomatic individuals by electron beam computed tomography and signal-averaged electrocardiogram is not settled. Unfortunately, an effective drug is not available is not available at present, but quinidine has a place in treatment. New promising drugs are emerging like cilostazol and tedisamil. At present, implantation of an ICD is the only effective means of preventing sudden death. (author)
The Spectrum of Epidemiology Underlying Sudden Cardiac Death
Hayashi, Meiso; Shimizu, Wataru; Albert, Christine M.
2015-01-01
Sudden cardiac death (SCD) from cardiac arrest is a major international public health problem accounting for an estimated 15–20% of all deaths. Although resuscitation rates are generally improving throughout the world, the majority of individuals who suffer a sudden cardiac arrest will not survive. SCD most often develops in older adults with acquired structural heart disease, but it also rarely occurs in the young, where it is more commonly due to inherited disorders. Coronary heart disease (CHD) is known to be the most common pathology underlying SCD, followed by cardiomyopathies, inherited arrhythmia syndromes, and valvular heart disease. Over the past three decades, declines in SCD rates have not been as steep as for other causes of CHD deaths, and there is a growing fraction of SCDs not due to CHD and/or ventricular arrhythmias, particularly among certain subsets of the population. The growing heterogeneity of the pathologies and mechanisms underlying SCD present major challenges for SCD prevention, which are magnified further by a frequent lack of recognition of the underlying cardiac condition prior to death. Multifaceted preventative approaches, which address risk factors in seemingly low risk and known high-risk populations will be required to decrease the burden of SCD. In this Compendium, we review the wide-ranging spectrum of epidemiology underlying SCD within both the general population and in high-risk subsets with established cardiac disease placing an emphasis on recent global trends, remaining uncertainties, and potential targeted preventive strategies. PMID:26044246
Approximate solutions to Mathieu's equation
Wilkinson, Samuel A.; Vogt, Nicolas; Golubev, Dmitry S.; Cole, Jared H.
2018-06-01
Mathieu's equation has many applications throughout theoretical physics. It is especially important to the theory of Josephson junctions, where it is equivalent to Schrödinger's equation. Mathieu's equation can be easily solved numerically, however there exists no closed-form analytic solution. Here we collect various approximations which appear throughout the physics and mathematics literature and examine their accuracy and regimes of applicability. Particular attention is paid to quantities relevant to the physics of Josephson junctions, but the arguments and notation are kept general so as to be of use to the broader physics community.
Approximate Inference for Wireless Communications
DEFF Research Database (Denmark)
Hansen, Morten
This thesis investigates signal processing techniques for wireless communication receivers. The aim is to improve the performance or reduce the computationally complexity of these, where the primary focus area is cellular systems such as Global System for Mobile communications (GSM) (and extensions...... to the optimal one, which usually requires an unacceptable high complexity. Some of the treated approximate methods are based on QL-factorization of the channel matrix. In the work presented in this thesis it is proven how the QL-factorization of frequency-selective channels asymptotically provides the minimum...
Quantum tunneling beyond semiclassical approximation
International Nuclear Information System (INIS)
Banerjee, Rabin; Majhi, Bibhas Ranjan
2008-01-01
Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.
Generalized Gradient Approximation Made Simple
International Nuclear Information System (INIS)
Perdew, J.P.; Burke, K.; Ernzerhof, M.
1996-01-01
Generalized gradient approximations (GGA close-quote s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. copyright 1996 The American Physical Society
Impulse approximation in solid helium
International Nuclear Information System (INIS)
Glyde, H.R.
1985-01-01
The incoherent dynamic form factor S/sub i/(Q, ω) is evaluated in solid helium for comparison with the impulse approximation (IA). The purpose is to determine the Q values for which the IA is valid for systems such a helium where the atoms interact via a potential having a steeply repulsive but not infinite hard core. For 3 He, S/sub i/(Q, ω) is evaluated from first principles, beginning with the pair potential. The density of states g(ω) is evaluated using the self-consistent phonon theory and S/sub i/(Q,ω) is expressed in terms of g(ω). For solid 4 He resonable models of g(ω) using observed input parameters are used to evaluate S/sub i/(Q,ω). In both cases S/sub i/(Q, ω) is found to approach the impulse approximation S/sub IA/(Q, ω) closely for wave vector transfers Q> or approx. =20 A -1 . The difference between S/sub i/ and S/sub IA/, which is due to final state interactions of the scattering atom with the remainder of the atoms in the solid, is also predominantly antisymmetric in (ω-ω/sub R/), where ω/sub R/ is the recoil frequency. This suggests that the symmetrization procedure proposed by Sears to eliminate final state contributions should work well in solid helium
Finite approximations in fluid mechanics
International Nuclear Information System (INIS)
Hirschel, E.H.
1986-01-01
This book contains twenty papers on work which was conducted between 1983 and 1985 in the Priority Research Program ''Finite Approximations in Fluid Mechanics'' of the German Research Society (Deutsche Forschungsgemeinschaft). Scientists from numerical mathematics, fluid mechanics, and aerodynamics present their research on boundary-element methods, factorization methods, higher-order panel methods, multigrid methods for elliptical and parabolic problems, two-step schemes for the Euler equations, etc. Applications are made to channel flows, gas dynamical problems, large eddy simulation of turbulence, non-Newtonian flow, turbomachine flow, zonal solutions for viscous flow problems, etc. The contents include: multigrid methods for problems from fluid dynamics, development of a 2D-Transonic Potential Flow Solver; a boundary element spectral method for nonstationary viscous flows in 3 dimensions; navier-stokes computations of two-dimensional laminar flows in a channel with a backward facing step; calculations and experimental investigations of the laminar unsteady flow in a pipe expansion; calculation of the flow-field caused by shock wave and deflagration interaction; a multi-level discretization and solution method for potential flow problems in three dimensions; solutions of the conservation equations with the approximate factorization method; inviscid and viscous flow through rotating meridional contours; zonal solutions for viscous flow problems
Plasma Physics Approximations in Ares
International Nuclear Information System (INIS)
Managan, R. A.
2015-01-01
Lee & More derived analytic forms for the transport properties of a plasma. Many hydro-codes use their formulae for electrical and thermal conductivity. The coefficients are complex functions of Fermi-Dirac integrals, Fn( μ/θ ), the chemical potential, μ or ζ = ln(1+e μ/θ ), and the temperature, θ = kT. Since these formulae are expensive to compute, rational function approximations were fit to them. Approximations are also used to find the chemical potential, either μ or ζ . The fits use ζ as the independent variable instead of μ/θ . New fits are provided for A α (ζ ),A β (ζ ), ζ, f(ζ ) = (1 + e -μ/θ )F 1/2 (μ/θ), F 1/2 '/F 1/2 , F c α , and F c β . In each case the relative error of the fit is minimized since the functions can vary by many orders of magnitude. The new fits are designed to exactly preserve the limiting values in the non-degenerate and highly degenerate limits or as ζ→ 0 or ∞. The original fits due to Lee & More and George Zimmerman are presented for comparison.
The Impact of Sudden Gains in Cognitive Behavioral Therapy for Posttraumatic Stress Disorder
Kelly, Kacie A.; Rizvi, Shireen L.; Monson, Candice M.; Resick, Patricia A.
2009-01-01
This study investigated sudden gains, i.e., rapid and stable improvements, in posttraumatic stress disorder (PTSD) symptoms that may occur in cognitive–behavioral therapy. Twenty-nine of 72 participants (39.2%) experienced a sudden gain during treatment. Mixed model ANOVAs analyzed sudden gains impact on clinician-rated PTSD symptom severity, patient-rated PTSD symptom severity, and patient-rated depressive symptom severity. Sudden gains in PTSD symptomology were associated with greater reductions in PTSD symptom severity for the avoidance/numbing and hyperarousal symptom clusters at posttreatment. By 6-month follow-up, the sudden gains group had maintained those reductions in symptoms, but the nonsudden gains group had achieved equal reductions in symptom severity. Participants experiencing sudden gains on PTSD measures had lower depression severity at posttreatment and follow-up. PMID:19637322
Profile of sudden death in an adult population (1999-2008).
LENUS (Irish Health Repository)
Downes, M R
2010-06-01
Sudden death is the sudden and unexpected death of an individual within 24 hours of symptom onset. The vast majority of these cases are found, at autopsy, to be due to underlying ischaemic cardiac disease. We retrospectively reviewed all adult post mortems performed at Beaumont Hospital over a decade (1999-2008). Our aim was to identify all sudden death cases (natural and accidental) and subclassify them according to age profile and organ system involved. We identified 1230 sudden death cases in the review period with 775 (63%) deaths attributable to ischaemic heart disease. The rate of sudden death remained constant over the decade with 663 (54%) deaths occurring in the first five years. Our negative autopsy rate was 2.8% corresponding to 35 cases. This is the first Irish study to retrospectively review all adult sudden deaths within a defined catchment area and analyse them as outlined above.
Chroni, M; Prappa, E; Kokkevi, I
2018-04-01
Septic emboli are an unusual cause of sudden sensorineural hearing loss, for which few reports exist in the literature. This paper presents two cases of sudden sensorineural hearing loss, initially considered as idiopathic, but which were caused by septic emboli. Hearing loss in these cases was bilateral, sequential and total. The first patient had mild fever one week prior to their presentation with sudden sensorineural hearing loss; the other patient had no additional symptoms at presentation. These patients were later diagnosed with infective endocarditis, at two and seven months following the sudden sensorineural hearing loss respectively, showing that septic emboli had been the cause of sudden sensorineural hearing loss. Septic emboli should be considered as a possible cause of sudden sensorineural hearing loss in cases of total hearing loss. This form of hearing loss should prompt the otolaryngologist to further investigate for infective endocarditis.
Approximating the minimum cycle mean
Directory of Open Access Journals (Sweden)
Krishnendu Chatterjee
2013-07-01
Full Text Available We consider directed graphs where each edge is labeled with an integer weight and study the fundamental algorithmic question of computing the value of a cycle with minimum mean weight. Our contributions are twofold: (1 First we show that the algorithmic question is reducible in O(n^2 time to the problem of a logarithmic number of min-plus matrix multiplications of n-by-n matrices, where n is the number of vertices of the graph. (2 Second, when the weights are nonnegative, we present the first (1 + ε-approximation algorithm for the problem and the running time of our algorithm is ilde(O(n^ω log^3(nW/ε / ε, where O(n^ω is the time required for the classic n-by-n matrix multiplication and W is the maximum value of the weights.
Nonlinear approximation with dictionaries I. Direct estimates
DEFF Research Database (Denmark)
Gribonval, Rémi; Nielsen, Morten
2004-01-01
We study various approximation classes associated with m-term approximation by elements from a (possibly) redundant dictionary in a Banach space. The standard approximation class associated with the best m-term approximation is compared to new classes defined by considering m-term approximation w...
Approximate cohomology in Banach algebras | Pourabbas ...
African Journals Online (AJOL)
We introduce the notions of approximate cohomology and approximate homotopy in Banach algebras and we study the relation between them. We show that the approximate homotopically equivalent cochain complexes give the same approximate cohomologies. As a special case, approximate Hochschild cohomology is ...
DEFF Research Database (Denmark)
Larsen, TB; Nørgaard-Pedersen, B; Lundemose, JB
2000-01-01
in the child. This prompted us to investigate these genetic markers of thromboembolic disease in 121 cases of sudden infant death syndrome and in relevant controls, in the expectation of a more frequent occurrence of these markers if thrombosis is an etiological factor in sudden infant death syndrome...... or unknown risk factors for thrombosis as possible etiological factors for sudden infant death syndrome. It is likely that we must continuously employ the exclusion principle on possible etiological causes in genetic material from a large group of victims of sudden infant death syndrome if the phenomenon...
Entanglement dynamics following a sudden quench: An exact solution
Ghosh, Supriyo; Gupta, Kumar S.; Srivastava, Shashi C. L.
2017-12-01
We present an exact and fully analytical treatment of the entanglement dynamics for an isolated system of N coupled oscillators following a sudden quench of the system parameters. The system is analyzed using the solutions of the time-dependent Schrodinger's equation, which are obtained by solving the corresponding nonlinear Ermakov equations. The entanglement entropies exhibit a multi-oscillatory behaviour, where the number of dynamically generated time scales increases with N. The harmonic chains exhibit entanglement revival and for larger values of N (> 10), we find near-critical logarithmic scaling for the entanglement entropy, which is modulated by a time-dependent factor. The N = 2 case is equivalent to the two-site Bose-Hubbard model in the tunneling regime, which is amenable to empirical realization in cold-atom systems.
Sudden flux change studies in high field superconducting accelerator magnets
International Nuclear Information System (INIS)
Feher, S.; Bordini, B.; Carcagno, R.; Makulski, A.; Orris, D.F.; Pischalnikov, Y.M.; Sylvester, C.; Tartaglia, M.; Tompkins, J.C.; Zlobin, A.V.
2004-01-01
As part of the High Field Magnet Program at Fermilab many magnets have been tested which utilize multi strand Rutherford type cable made of state-of-the art Nb 3 Sn strands. During these magnet tests we observed sudden flux changes by monitoring coil voltages and the magnetic field close to the magnets. These flux changes might be linked to magnet instabilities. The voltage spike signals were correlated with quench antenna signals, a strong indication that these are magnet phenomena. With a new high resolution voltage spike detection system, we were able to observe the detailed structure of the spikes. Two fundamentally different signal shapes were distinguished, most likely generated by different mechanisms
Increased risk of sudden cardiac arrest in obstructive pulmonary disease
DEFF Research Database (Denmark)
Warnier, Miriam Jacoba; Blom, Marieke Tabo; Bardai, Abdennasser
2013-01-01
BACKGROUND: We aimed to determine whether (1) patients with obstructive pulmonary disease (OPD) have an increased risk of sudden cardiac arrest (SCA) due to ventricular tachycardia or fibrillation (VT/VF), and (2) the SCA risk is mediated by cardiovascular risk-profile and/or respiratory drug use...... with electrocardiographic documentation of VT/VF were included. Conditional logistic regression analysis was used to assess the association between SCA and OPD. Pre-specified subgroup analyses were performed regarding age, sex, cardiovascular risk-profile, disease severity, and current use of respiratory drugs. RESULTS...... is associated with an increased observed risk of SCA. The most increased risk was observed in patients with a high cardiovascular risk-profile, and in those who received SABA and, possibly, those who received AC at the time of SCA....
SUDDEN NATURAL DEATHS IN MEDICOLEGAL CASES- AN AUTOPSY BASED STUDY
Directory of Open Access Journals (Sweden)
C. S. Sreedevi
2017-01-01
Full Text Available BACKGROUND Death occurring in apparently healthy individual in a case of natural death may arise suspicion of foul play. In these circumstances these cases may be subjected to medicolegal autopsy. The disease condition may be unknown to the individual and the relatives. This study was done to review the exact cause of death in sudden unexpected deaths, and enabling or assisting the legal authorities in detection of crime, to prove or disprove the foul play. Body mass index is the most frequently used indicator of body fatness. An attempt is made to find out whether there is any significant relationship between BMI and the risk for sudden cardiac death. MATERIALS AND METHODS Data of 50 cases of sudden unexpected death brought for medicolegal autopsy at govt. T.D. medical college Alappuzha in the year 2010 were studied and information were collected from the postmortem records. Data was entered in the proforma. The histopathological examination findings of relevant cases were studied. Analysis was done using MS EXCEL and Chi-square test was used as the test of significance in the comparison between two categorical variables. RESULTS In 50 cases, male predominance was observed and 88% were males in which 50% of males died of atherosclerotic occlusive coronary artery disease and among females 33% died of myocardial infarction. While considering the systemic distribution of cause of death, the cardiovascular system was found to be most commonly affected, 33 cases (66% followed by respiratory system 7 cases (14%. In 4 (8% cases gastrointestinal system was affected. In Two cases (4% central nervous system was affected and others were generalized infection, which constituted 2 cases. Out of 33 cases observed in cardiovascular system the commonest cause being the atherosclerotic occlusive coronary artery diseases involving 27 cases (81.81% in which the predominant involvement was seen in left anterior descending artery 21 cases (77.77% followed by right
Surprises in the suddenly-expanded infinite well
International Nuclear Information System (INIS)
Aslangul, Claude
2008-01-01
I study the time evolution of a particle prepared in the ground state of an infinite well after the latter is suddenly expanded. It turns out that the probability density |Ψ(x, t)| 2 shows up quite a surprising behaviour: for definite times, plateaux appear for which |Ψ(x, t)| 2 is constant on finite intervals for x. Elements of theoretical explanation are given by analysing the singular component of the second derivative ∂ xx Ψ(x, t). Analytical closed expressions are obtained for some specific times, which easily allow us to show that, at these times, the density organizes itself into regular patterns provided the size of the box is large enough; more, above some critical size depending on the specific time, the density patterns are independent of the expansion parameter. It is seen how the density at these times simply results from a construction game with definite rules acting on the pieces of the initial density
Cardiac symptoms before sudden cardiac death caused by hypertrophic cardiomyopathy
DEFF Research Database (Denmark)
Lynge, Thomas Hadberg; Risgaard, Bjarke; Jabbari, Reza
2016-01-01
AIMS: Hypertrophic cardiomyopathy (HCM) is a frequent cause of sudden cardiac death (SCD) among the young (SCDY). The aim of this study was to characterize symptoms before SCDY due to HCM. METHODS AND RESULTS: Through review of all death certificates, we identified all SCDs in Danes aged 1-35 years...... in 2000-2009. Nationwide we included all deaths (n = 8756) and identified 431 autopsied SCDYs. All available records from hospitals and general practitioners were retrieved. To compare symptoms, we included a control groups consisting of traffic accident victims (n = 74). In the 10-year study period, 431...... autopsied SCDY cases were reviewed and 38 cases (9%) were included, of which 22 (58%) had morphologic findings diagnostic of HCM and 16 (42%) had findings suggestive, but not diagnostic, of HCM ('possible HCM'). Cardiac symptoms >1 h prior to death were reported in 21 (55%) of cases, and 16 (42%) sought...
Sudden cardiac death and coronary disease in the young
DEFF Research Database (Denmark)
Zachariasardóttir, Sára; Risgaard, Bjarke; Ågesen, Frederik Nybye
2017-01-01
BACKGROUND: Sudden cardiac death caused by coronary artery disease (CAD-SCD) is the most frequent cause of SCD in persons ..., CAD-SCD victims aged 36-49years had more severe atherosclerosis in all coronary arteries, more multi-vessel disease (29% vs. 15%, p=0.049) and less commonly (38% vs. 54%, p=0.039) acute coronary occlusion than victims ... to death. CONCLUSION: This nationwide study found several differences in the pathologic lesions of the heart in victims aged 18-35 and 36-49years, which might be associated with different disease progression leading to death in these age groups. We also report a high frequency of cardiac symptoms prior...
Subclinical hyperthyroidism and sudden unexpected death in epilepsy.
Scorza, Fulvio A; Arida, Ricardo M; Cysneiros, Roberta M; Terra, Vera C; de Albuquerque, Marly; Machado, Hélio R; Cavalheiro, Esper A
2010-04-01
Epilepsy is the most common serious neurological condition and sudden unexpected death in epilepsy (SUDEP) is the most important direct epilepsy-related cause of death. Information concerning risk factors for SUDEP is conflicting, but high seizure frequency is a potential risk factor. Additionally, potential pathomechanisms for SUDEP are unknown, but it is very probable that cardiac arrhythmias during and between seizures or transmission of epileptic activity to the heart via the autonomic nervous system potentially play a role. In parallel, several studies have shown a link between hormones and epilepsy. However, exact knowledge regarding the association of thyroid hormones and epilepsy is lacking. As subclinical hyperthyroidism has been linked with increased risk of cardiovascular disease, we propose in this paper that SUDEP, at least in some cases, could be related with subclinical thyroid dysfunction. (c) 2009 Elsevier Ltd. All rights reserved.
Combustion instabilities in sudden expansion oxy-fuel flames
Energy Technology Data Exchange (ETDEWEB)
Ditaranto, Mario; Hals, Joergen [Department of Energy Processes, SINTEF Energy Research, 7465 Trondheim (Norway)
2006-08-15
An experimental study on combustion instability is presented with focus on oxy-fuel type combustion. Oxidants composed of CO{sub 2}/O{sub 2} and methane are the reactants flowing through a premixer-combustor system. The reaction starts downstream a symmetric sudden expansion and is at the origin of different instability patterns depending on oxygen concentration and Reynolds number. The analysis has been conducted through measurement of pressure, CH* chemiluminescence, and velocity. As far as stability is concerned, oxy-fuel combustion with oxygen concentration similar to that found in air combustion cannot be sustained, but requires at least 30% oxygen to perform in a comparable manner. Under these conditions and for the sudden expansion configuration used in this study, the instability is at low frequency and low amplitude, controlled by the flame length inside the combustion chamber. Above a threshold concentration in oxygen dependent on equivalence ratio, the flame becomes organized and concentrated in the near field. Strong thermoacoustic instability is then triggered at characteristic acoustic modes of the system. Different modes can be triggered depending on the ratio of flame speed to inlet velocity, but for all types of instability encountered, the heat release and pressure fluctuations are linked by a variation in mass-flow rate. An acoustic model of the system coupled with a time-lag-based flame model made it possible to elucidate the acoustic mode selection in the system as a function of laminar flame speed and Reynolds number. The overall work brings elements of reflection concerning the potential risk of strong pressure oscillations in future gas turbine combustors for oxy-fuel gas cycles. (author)
Environmental risk factors for sudden infant death syndrome in Japan.
Hirabayashi, Masako; Yoshinaga, Masao; Nomura, Yuichi; Ushinohama, Hiroya; Sato, Seiichi; Tauchi, Nobuo; Horigome, Hitoshi; Takahashi, Hideto; Sumitomo, Naokata; Shiraishi, Hirohiko; Nagashima, Masami
2016-12-01
While the prevalence of sudden infant death syndrome (SIDS) has decreased worldwide, this decline has plateaued recently. Strategies are needed to resume the constant decrease of SIDS in Japan. A prospective electrocardiographic screening program for infants was performed between July 2010 and March 2011. Parents of 4319 infants were asked about environmental factors related to SIDS through questionnaires at a one-month medical checkup and one year. Parental awareness of prone position, smoke exposure, and breast feeding as environmental factors were 81.4 %, 69.0 %, and 47.8 %, respectively. The prevalence of laying infants exclusively in a supine position was 96.7 %. At the one-month medical checkup, smoking prevalence was 41.7 % in fathers and 2.1 % in mothers. Maternal smoking prevalence was significantly increased at one year after (p Japan. Smoking cessation programs should be further implemented for parents to decrease risks of SIDS in Japan. What is Known: • The prevalence of sudden infant death syndrome (SIDS) has decreased worldwide, however, this decline has plateaued recently. What is New: • Most infants were laid sleeping in the supine position (96.7 %) and were fed breast milk or a mix of expressed milk and formula (92.7 %), and 2.1 % of mothers smoked at the one-month medical checkup. • Maternal smoking prevalence significantly increased from the one-month medical checkup to one year later, and smoking mothers were more likely to feed infants by formula rather than breast milk. • Independent risk factors for new or continued maternal smoking habits included younger maternal age, maternal smoking habits at one month, and paternal smoking habits one year later.
Mitral valve prolapse and sudden cardiac arrest in the community.
Narayanan, Kumar; Uy-Evanado, Audrey; Teodorescu, Carmen; Reinier, Kyndaron; Nichols, Gregory A; Gunson, Karen; Jui, Jonathan; Chugh, Sumeet S
2016-02-01
Mitral valve prolapse (MVP) is relatively common in the general population with recently reported prevalence of 1% and familial clustering (Framingham Heart Study). However, its association with ventricular arrhythmias and sudden cardiac arrest (SCA) remains controversial. The purpose of this study was to characterize the frequency and clinical profile of patients with MVP who suffer SCA in the community. Patients with SCA cases were prospectively identified in the population-based Oregon Sudden Unexpected Death Study (population ~1 million). The presence of MVP was identified from echocardiograms recorded prior but unrelated to the SCA event. The detailed clinical profile of patients with SCA and MVP was compared with that of SCA patients without MVP to identify potential differences. A total of 729 SCA patients were evaluated over a 12-year period (mean age 69.5 ± 14.8 years; 64.6% men). MVP was observed in 17 (2.3%) prior to the SCA event (95% confidence interval 1.2%-3.4%). Mitral regurgitation was present in 14 SCA patients with MVP (82.3%) and was moderate or severe in 10 (58.8%). Compared with SCA patients without MVP, SCA patients with MVP were younger (mean age 60.9 ± 16.4 years vs 69.7 ± 14.7 years; P = .02), with fewer risk factors (diabetes 5.9% vs 46.4%; P = .001; hypertension 41.2% vs 78.9%; P = .001) or known coronary disease (29.4% vs 65.6%; P MVP was observed in a small proportion (2.3%) of SCA patients in the general population, suggesting a low risk overall. Since SCA patients with MVP were characterized by younger age and relatively low cardiovascular comorbidity, a focus on imaging for valve structure/insufficiency as well as genetics could aid future risk stratification approaches. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
Characteristics of sudden arrhythmic death in a diverse, urban community.
Steinhaus, Daniel A; Vittinghoff, Eric; Moffatt, Ellen; Hart, Amy P; Ursell, Philip; Tseng, Zian H
2012-01-01
Sudden cardiac death (SCD) remains a major public health problem; however, its true burden remains unknown with widely variable estimates of its incidence. We aimed to examine the contemporary epidemiology and autopsy characteristics of SCD in an ethnically diverse community. Three physicians reviewed all deaths of individuals aged ≥20 years reported to the San Francisco medical examiner in 2007 for presentations fitting World Health Organization (WHO) SCD criteria-within 1 hour of symptom onset (witnessed) or within 24 hours of being observed alive and symptom free (unwitnessed). After comprehensive review of medical examiner investigation, WHO SCDs were classified as sudden arrhythmic death (SAD) or nonarrhythmic death. Coronary artery disease (CAD) and cardiac mass were evaluated in all SADs undergoing autopsy and compared with demographically similar accidental trauma control deaths. We identified 252 WHO SCDs; 145 were SADs. Men had a 2.2-fold higher SAD rate (P < .0005). Blacks had a 3.15-fold higher SAD rate compared with whites (P = .003). Significant CAD was present in 38.9% of SADs and associated with higher SAD risk compared with control deaths (OR 2.58, 95% CI 1.12-5.97, P = .026). Mean cardiac mass was linearly associated with risk for SAD in cases without significant CAD (OR 2.06 per 100 g, 95% CI 1.43-2.98, P < .0005). In a diverse, urban population, SAD incidence varied substantially by gender and race. Significant CAD accounted for far fewer SADs than previous studies but remained associated with a 2.6-fold higher risk as compared with control deaths. These findings may reflect the evolving contemporary epidemiology of SCD. Copyright © 2012 Mosby, Inc. All rights reserved.
Sudden cardiac arrest in people with epilepsy in the community
Lamberts, Robert J.; Blom, Marieke T.; Wassenaar, Merel; Bardai, Abdennasser; Leijten, Frans S.; de Haan, Gerrit-Jan; Sander, Josemir W.; Thijs, Roland D.
2015-01-01
Objective: To ascertain whether characteristics of ventricular tachycardia/fibrillation (VT/VF) differed between people with epilepsy and those without and which individuals with epilepsy were at highest risk. Methods: We ascertained 18 people with active epilepsy identified in a community-based registry of sudden cardiac arrest (SCA) with ECG-confirmed VT/VF (cases). We compared them with 470 individuals with VT/VF without epilepsy (VT/VF controls) and 54 individuals with epilepsy without VT/VF (epilepsy controls). Data on comorbidity, epilepsy severity, and medication use were collected and entered into (conditional) logistic regression models to identify determinants of VT/VF in epilepsy. Results: In most cases, there was an obvious (10/18) or presumed cardiovascular cause (5/18) in view of preexisting heart disease. In 2 of the 3 remaining events, near–sudden unexpected death in epilepsy (SUDEP) was established after successful resuscitation. Cases had a higher prevalence of congenital/inherited heart disease (17% vs 1%, p = 0.002), and experienced VT/VF at younger age (57 vs 64 years, p = 0.023) than VT/VF controls. VT/VF in cases occurred more frequently at/near home (89% vs 58%, p = 0.009), and was less frequently witnessed (72% vs 89%, p = 0.048) than in VT/VF controls. Cases more frequently had clinically relevant heart disease (50% vs 15%, p = 0.005) and intellectual disability (28% vs 1%, p epilepsy controls. Conclusion: Cardiovascular disease rather than epilepsy characteristics is the main determinant of VT/VF in people with epilepsy in the community. SCA and SUDEP are partially overlapping disease entities. PMID:26092917
Hess, Paul L; Al-Khalidi, Hussein R; Friedman, Daniel J; Mulder, Hillary; Kucharska-Newton, Anna; Rosamond, Wayne R; Lopes, Renato D; Gersh, Bernard J; Mark, Daniel B; Curtis, Lesley H; Post, Wendy S; Prineas, Ronald J; Sotoodehnia, Nona; Al-Khatib, Sana M
2017-08-23
Prior studies have demonstrated a link between the metabolic syndrome and increased risk of cardiovascular mortality. Whether the metabolic syndrome is associated with sudden cardiac death is uncertain. We characterized the relationship between sudden cardiac death and metabolic syndrome status among participants of the ARIC (Atherosclerosis Risk in Communities) Study (1987-2012) free of prevalent coronary heart disease or heart failure. Among 13 168 participants, 357 (2.7%) sudden cardiac deaths occurred during a median follow-up of 23.6 years. Participants with the metabolic syndrome (n=4444) had a higher cumulative incidence of sudden cardiac death than those without it (n=8724) (4.1% versus 2.3%, P metabolic syndrome, the metabolic syndrome was independently associated with sudden cardiac death (hazard ratio, 1.70, 95% confidence interval, 1.37-2.12, P metabolic syndrome criteria components. The risk of sudden cardiac death varied according to the number of metabolic syndrome components (hazard ratio 1.31 per additional component of the metabolic syndrome, 95% confidence interval, 1.19-1.44, P metabolic syndrome was associated with a significantly increased risk of sudden cardiac death irrespective of sex or race. The risk of sudden cardiac death was proportional to the number of metabolic syndrome components. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.
Sudden unexpected death in children with a previously diagnosed cardiovascular disorder
Polderman, Florens N.; Cohen, Joeri; Blom, Nico A.; Delhaas, Tammo; Helbing, Wim A.; Lam, Jan; Sobotka-Plojhar, Marta A.; Temmerman, Arno M.; Sreeram, Narayanswani
2004-01-01
BACKGROUND: It is known that children with previously diagnosed heart defects die suddenly. The causes of death are often unknown. OBJECTIVE: The aim of the study was to identify all infants and children within the Netherlands with previously diagnosed heart disease who had a sudden unexpected death
Sudden unexpected death in children with a previously diagnosed cardiovascular disorder
Polderman, F.N.; Cohen, Joeri; Blom, N.A.; Delhaas, T.; Helbing, W.A.; Lam, J.; Sobotka-Plojhar, M.A.; Temmerman, Arno M.; Sreeram, N.
2004-01-01
Background: It is known that children with previously diagnosed heart defects die suddenly. The causes of death are often unknown. Objective: The aim of the study was to identify all infants and children within the Netherlands with previously diagnosed heart disease who had a sudden unexpected death
Susan J. Frankel
2017-01-01
This special issue of Forest Phytophthoras serves as part of the proceedings from the Sixth Sudden Oak Death Science Symposium held June 21 -23, 2016 at Fort Mason Center in San Francisco, CA, USA. The symposium marked almost 16 years to the day that David Rizzo (UC Davis) and Matteo Garbelotto (UC Berkeley) identified the cause of sudden oak death to be a previously...
Adaptation to sudden unexpected loading of the low back - the effects of repeated trials
DEFF Research Database (Denmark)
Skotte, J.H.; Fallentin, N.; Pedersen, Mogens Theisen
2004-01-01
The purpose of this study was to investigate short-term changes in reactions to sudden unexpected loading of the low back. The study utilized a set-up where a horizontal force of 58 N pointing forward suddenly was applied to the upper part of the subject's trunk. EMG activity from the erector...
A 23-year review of sudden natural death autopsies in the Niger ...
African Journals Online (AJOL)
Background: Death occurring suddenly especially when the victim was active and recently fit, call for attention and thorough investigation to rule out secret homicide. Aim: To study the pattern of sudden natural death in the Niger Delta region of Nigeria. Methodology: The coroner's autopsy reports and hospital autopsy ...
Utility of Post-Mortem Genetic Testing in Cases of Sudden Arrhythmic Death Syndrome
Lahrouchi, Najim; Raju, Hariharan; Lodder, Elisabeth M.; Papatheodorou, Efstathios; Ware, James S.; Papadakis, Michael; Tadros, Rafik; Cole, Della; Skinner, Jonathan R.; Crawford, Jackie; Love, Donald R.; Pua, Chee J.; Soh, Bee Y.; Bhalshankar, Jaydutt D.; Govind, Risha; Tfelt-Hansen, Jacob; Winkel, Bo G.; van der Werf, Christian; Wijeyeratne, Yanushi D.; Mellor, Greg; Till, Jan; Cohen, Marta C.; Tome-Esteban, Maria; Sharma, Sanjay; Wilde, Arthur A. M.; Cook, Stuart A.; Bezzina, Connie R.; Sheppard, Mary N.; Behr, Elijah R.
2017-01-01
Sudden arrhythmic death syndrome (SADS) describes a sudden death with negative autopsy and toxicological analysis. Cardiac genetic disease is a likely etiology. This study investigated the clinical utility and combined yield of post-mortem genetic testing (molecular autopsy) in cases of SADS and
Tympanotomy and sealing of the round window for treatment of sudden deafness
DEFF Research Database (Denmark)
Ul-Mulk, Jamshaid; Friis, Søren; Hahn, Christoffer Holst
2011-01-01
The objective of this study was to evaluate the effectiveness of explorative tympanotomy and sealing of the round window in patients diagnosed with sudden deafness.......The objective of this study was to evaluate the effectiveness of explorative tympanotomy and sealing of the round window in patients diagnosed with sudden deafness....
Sudden Oak Death, Phytophthora ramorum: A Persistent Threat to Oaks and Other Tree Species
S.J. Frankel; K.M. Palmieri
2014-01-01
This paper reviews the status and management of sudden oak death and âsudden larch deathâ in the urban and wildland forests of California, Oregon, and the UK. The causal pathogen, Phytophthora ramorum, was discovered in all three locations over a decade ago; however, efforts to contain and eliminate infestations have been unsuccessful. These less...
Sudden oak death and Phytophthora ramorum: a summary of the literature
John T. Kliejunas
2010-01-01
Sudden oak death and Phytophthora ramorum, both first recognized about a decade ago, have been the subject of hundreds of scientific and popular press articles. This document presents a comprehensive, concise summary of sudden oak death and P. ramorum research findings and management activities. Topics covered include...
Survival and sudden cardiac death after septal ablation for hypertrophic obstructive cardiomyopathy
DEFF Research Database (Denmark)
Jensen, Morten Kvistholm; Havndrup, Ole; Hassager, Christian
2011-01-01
Reports of long-term survival and the risk of sudden cardiac death (SCD) after percutaneous transluminal septal myocardial ablation (PTSMA) in patients with hypertrophic obstructive cardiomyopathy (HOCM) are sparse.......Reports of long-term survival and the risk of sudden cardiac death (SCD) after percutaneous transluminal septal myocardial ablation (PTSMA) in patients with hypertrophic obstructive cardiomyopathy (HOCM) are sparse....
Cardiac symptoms before sudden cardiac death caused by coronary artery disease
DEFF Research Database (Denmark)
Jabbari, Reza; Risgaard, Bjarke; Holst, Anders G
2013-01-01
The aim of this nationwide case-control study was to identify and characterise symptoms before sudden death of young persons who had died due to coronary artery disease (CAD).......The aim of this nationwide case-control study was to identify and characterise symptoms before sudden death of young persons who had died due to coronary artery disease (CAD)....
Utility of Post-Mortem Genetic Testing in Cases of Sudden Arrhythmic Death Syndrome
DEFF Research Database (Denmark)
Lahrouchi, Najim; Raju, Hariharan; Lodder, Elisabeth M
2017-01-01
BACKGROUND: Sudden arrhythmic death syndrome (SADS) describes a sudden death with negative autopsy and toxicological analysis. Cardiac genetic disease is a likely etiology. OBJECTIVES: This study investigated the clinical utility and combined yield of post-mortem genetic testing (molecular autopsy...
Population-based studies of antithyroid drugs and sudden cardiac death
C. van Noord (Charlotte); M.C.J.M. Sturkenboom (Miriam); S.M.J.M. Straus (Sabine); A. Hofman (Albert); J.C.M. Witteman (Jacqueline); B.H.Ch. Stricker (Bruno)
2009-01-01
textabstractWHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Thyroid hormone free T4 is associated with QTc-interval prolongation, which is a risk factor for sudden cardiac death. • The association between hyperthyroidism and ventricular arrhythmias or sudden cardiac death has been reported in several
Zhao, Peng; Wang, Ji-Gang; Gao, Peng; Li, Xia; Brewer, Rubell
2016-01-01
The aim of this study is to identify and subclassify sudden natural death (sudden death from natural diseases) cases in Seychelles. A total of 484 sudden natural death cases with autopsy at the Clinical Pathology Laboratory, Victoria Hospital, Seychelles between 1997 through 2012 were retrospectively reviewed. Among them, 363 cases (75%) were male and 121 (25%) were female. The most frequent sudden deaths were attributed to cardiovascular diseases (78.5%), and then followed by infectious diseases (9.9%), and gastrointestinal diseases (9.1%). This is the largest population-based study on sudden natural deaths in Seychelles. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
The molecular autopsy: an indispensable step following sudden cardiac death in the young?
Boczek, Nicole J.; Tester, David J.; Ackerman, Michael J.
2013-01-01
Annually thousands of sudden deaths involving young individuals (autopsy. In fact, epidemiological studies have estimated that over half of sudden deaths involving previously healthy young individuals have no morphological abnormalities identifiable at autopsy. Cardiac channelopathies associated with structurally normal hearts such as long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and Brugada syndrome (BrS), leave no evidence to be found at autopsy, leaving investigators to only speculate that a lethal arrhythmia might lie at the heart of a sudden unexplained death (SUD). In cases of autopsy-negative SUD, continued investigation, through the use of a cardiological and genetic evaluation of first- or second-degree relatives and/or a molecular autopsy, may pinpoint the underlying mechanism attributing to the sudden death and allow for the identification of living family members with the pathogenic substrate that renders them vulnerable to an increased risk for cardiac events, including sudden death. PMID:22993115
Genetic testing to predict sudden cardiac death: current perspectives and future goals
Directory of Open Access Journals (Sweden)
Silvia G. Priori
2014-01-01
Full Text Available It is known that monogenic traits may predispose young and otherwise healthy individuals to die suddenly. Diseases such as Long QT Syndrome, Brugada Syndrome and Arrhythmogenic Right Ventricular Cardiomyopathy are well known causes of arrhythmic death in young individuals. For several years the concept of “genetic predisposition” to sudden cardiac death has been limited to these uncommon diseases. In the last few years clinical data have supported the view that risk of dying suddenly may cluster in families, supporting the hypothesis of a genetic component for sudden cardiac death. In this review I will try to provide an overview of current knowledge about genetics of sudden death. I will approach this topic by discussing first where we stand in the use of genetics for risk stratification and therapy selection in monogenic diseases and I will then move to discuss the contribution of genetics to patient profiling in acquired cardiovascular diseases.
Sudden death in young persons with uncontrolled asthma--a nationwide cohort study in Denmark
DEFF Research Database (Denmark)
Gullach, Anders Juul; Risgaard, Bjarke; Lynge, Thomas Hadberg
2015-01-01
BACKGROUND: Asthma is a common chronic disease among young adults, and several studies have reported increased mortality rates in patients with asthma. However, no study has described sudden unexpected death in a nationwide setting in patients with uncontrolled asthma. We defined uncontrolled...... in preventing sudden unexpected deaths. We therefore aimed to describe clinical characteristics, symptoms, causes of death, and contact with the healthcare system prior to sudden unexpected death in young persons with uncontrolled asthma. METHODS: Through the review of death certificates, we found 625 sudden...... individuals who suffered from uncontrolled asthma. This corresponds to an incidence rate of 0.32 per 100,000 person-years. The cause of death in 31 cases (63%) was sudden cardiac death, and in 13 cases (27%), it was a fatal asthma attack. Symptoms (chest pain, dyspnea, seizures, general malaise, syncope...
Prolonged QTc interval and risk of sudden cardiac death in a population of older adults
DEFF Research Database (Denmark)
Straus, Sabine M J M; Kors, Jan A; De Bruin, Marie L
2006-01-01
OBJECTIVES: This study sought to investigate whether prolongation of the heart rate-corrected QT (QTc) interval is a risk factor for sudden cardiac death in the general population. BACKGROUND: In developed countries, sudden cardiac death is a major cause of cardiovascular mortality. Prolongation...... of the QTc interval has been associated with ventricular arrhythmias, but in most population-based studies no consistent association was found between QTc prolongation and total or cardiovascular mortality. Only very few of these studies specifically addressed sudden cardiac death. METHODS: This study......). The association between a prolonged QTc interval and sudden cardiac death was estimated using Cox proportional hazards analysis. RESULTS: During an average follow-up period of 6.7 years (standard deviation, 2.3 years) 125 patients died of sudden cardiac death. An abnormally prolonged QTc interval (>450 ms in men...
Back muscle response to sudden trunk loading can be modified by training among healthcare workers
DEFF Research Database (Denmark)
Pedersen, Mogens Theisen; Essendrop, Morten; Skotte, Jørgen H.
2007-01-01
Study Design. Experimental study of the effect of physical training on the reaction to sudden back loading. Objective. To investigate the effect and sustainability of "on the job training" on the reaction to sudden back loading among employees at a geriatric ward. Summary of Background Data...... of the trunk (stopping time). Data on the possibilities of a training-induced improvement in the reflex response among workers exposed to sudden trunk loading on the job are, however, nonexistent, and there is no evidence of long-term benefits, i.e., the sustainability of a positive training effect. Methods....... Available data suggest that a delayed muscle reflex response to sudden trunk loading may increase the risk of low back injuries. We have previously shown that training may alter the response to sudden trunk loading in healthy subjects and decrease the time elapsed until stopping of the forward movement...
Haloperidol and sudden cardiac death in dementia: autopsy findings in psychiatric inpatients.
Ifteni, Petru; Grudnikoff, Eugene; Koppel, Jeremy; Kremen, Neil; Correll, Christoph U; Kane, John M; Manu, Peter
2015-12-01
Treatment with haloperidol has been shown, in studies using death certificates and prescription files, to be associated with an excess of sudden cardiac deaths, and regulatory warnings highlight this risk in patients with dementia. We used autopsy findings to determine whether the rate of sudden cardiac death is greater in cases of unexpected deaths of patients with dementia treated with haloperidol. From 1989 through 2013, 1219 patients with a primary diagnosis of dementia with behavioral disturbance were admitted to a psychiatric hospital, and 65 (5.3%) died suddenly. Sixty-five patients (5.3%) died unexpectedly. Complete post-mortem examinations after the sudden death were performed in 55 (84.6%) patients. Twenty-seven of the autopsied cases (49.1%) had been treated with haloperidol orally (2.2 mg ± 2.1 mg/day), the only antipsychotic used in this cohort. Univariable comparisons and multivariable regression analyses compared the groups of patients with or without sudden cardiac death. The leading causes of death were sudden cardiac death (32.7%), myocardial infarction (25.5% of patients), pneumonia (23.6%), and stroke (10.9%). Patients with sudden cardiac death and those with anatomically established cause of death were similar regarding the use of haloperidol (p = 0.5). Sudden cardiac death patients were more likely to suffer from Alzheimer's dementia (p = 0.027) and to have a past history of heart disease (p = 0.0094), and less likely to have been treated with a mood stabilizer (p = 0.024), but none of these variables were independent predictors of sudden cardiac death. Autopsy data suggest that oral haloperidol is not associated with increased risk of sudden cardiac death in psychiatric inpatients with dementia. Copyright © 2015 John Wiley & Sons, Ltd.
Sudden death in the first 2 years of life following immunization in the Republic of Korea.
Choe, Young June; Kim, Jong-Hee; Son, Hyun Jin; Bae, Geun-Ryang; Lee, Duk-hyoung
2012-12-01
Because the peak age for incidence of sudden deaths in infancy temporally coincides with the age of infant primary immunization, some have raised the question as to whether immunization is a risk factor for sudden death in infancy. Recent occurrence of two sudden deaths in infants in Korea has renewed concerns about the causal association between immunization and sudden deaths in infants. We carried out a retrospective review of data from the Korea Centers for Disease Control and Prevention Adverse Events Following Immunization Surveillance System and Vaccine Compensation programs. From 1994 to 2011, a total of 45 cases of sudden deaths in the first 2 years of life following immunization were reported in Korea. The causes of death were classified as follows: infectious diseases (n= 13); accidental injuries (n= 7); congenital abnormalities (n= 2); and malignancy (n= 1). Of 20 sudden deaths in infancy, nine deaths met Brighton Collaboration case definition level I and II, and therefore were classified as possible sudden infant death syndrome cases. Hepatitis B vaccine (n= 13) was the most frequent vaccine with temporal association with sudden deaths in the first 2 years of life. Few sudden deaths in the first 2 years of life following immunization have been reported, despite the use of universal immunization in Korea. The majority of deaths in infancy did not meet case definition for sudden infant death syndrome. Encouraging investigators to perform thorough investigation, including postmortem autopsy and death scene examination, may promote data comparability and provide guidance on decision-making in the vaccine-safety monitoring and response system in Korea. © 2012 The Authors. Pediatrics International © 2012 Japan Pediatric Society.
Electrocardiographic features of sudden unexpected death in epilepsy.
Chyou, Janice Y; Friedman, Daniel; Cerrone, Marina; Slater, William; Guo, Yu; Taupin, Daniel; O'Rourke, Sean; Priori, Silvia G; Devinsky, Orrin
2016-07-01
Sudden unexpected death in epilepsy (SUDEP) is the most common cause of epilepsy-related mortality. We hypothesized that electrocardiography (ECG) features may distinguish SUDEP cases from living subjects with epilepsy. Using a matched case-control design, we compared ECG studies of 12 consecutive cases of SUDEP over 10 years and 22 epilepsy controls matched for age, sex, epilepsy type (focal, generalized, or unknown/mixed type), concomitant antiepileptic, and psychotropic drug classes. Conduction intervals and prevalence of abnormal ventricular conduction diagnosis (QRS ≥110 msec), abnormal ventricular conduction pattern (QRS <110 msec, morphology of incomplete right or left bundle branch block or intraventricular conduction delay), early repolarization, and features of inherited cardiac channelopathies were assessed. Abnormal ventricular conduction diagnosis and pattern distinguished SUDEP cases from matched controls. Abnormal ventricular conduction diagnosis was present in two cases and no controls. Abnormal ventricular conduction pattern was more common in cases than controls (58% vs. 18%, p = 0.04). Early repolarization was similarly prevalent in cases and controls, but the overall prevalence exceeded that of published community-based cohorts. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.
Remittances as aid following major sudden-onset natural disasters.
Bragg, Catherine; Gibson, Glenn; King, Haleigh; Lefler, Ashley A; Ntoubandi, Faustin
2018-01-01
There is a general assumption, based on macroeconomic studies, that remittances will rise following major sudden-onset natural disasters. This is confirmed by a few assessments involving country-specific research, and usually short-term data. This study, questioning conventional wisdom, reviewed and graphed annual and quarterly remittance flows using International Monetary Fund and World Bank data from 2000-14 for 12 countries that confronted 18 major natural disasters. It found that, regardless of event type, annual remittances rose steadily from 2000-14 except for after the 2008-09 financial crisis. Post disaster, there was a quarterly increase in the majority of cases (confirming previous research) but there was seldom an annual increase in the year of the disaster greater than the average annual increase in 2000-14. It appears that remittance senders rush to provide assistance after a natural disaster, but since their own financial situation has not changed, the immediate increase is compensated by a later decrease. © 2018 The Author(s). Disasters © Overseas Development Institute, 2018.
Cardiac muscarinic receptor overexpression in sudden infant death syndrome.
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Angelo Livolsi
Full Text Available BACKGROUND: Sudden infant death syndrome (SIDS remains the leading cause of death among infants less than 1 year of age. Disturbed expression of some neurotransmitters and their receptors has been shown in the central nervous system of SIDS victims but no biological abnormality of the peripheral vago-cardiac system has been demonstrated to date. The present study aimed to seek vago-cardiac abnormalities in SIDS victims. The cardiac level of expression of muscarinic receptors, as well as acetylcholinesterase enzyme activity were investigated. METHODOLOGY/PRINCIPAL FINDINGS: Left ventricular samples and blood samples were obtained from autopsies of SIDS and children deceased from non cardiac causes. Binding experiments performed with [(3H]NMS, a selective muscarinic ligand, in cardiac membrane preparations showed that the density of cardiac muscarinic receptors was increased as shown by a more than doubled B(max value in SIDS (n = 9 SIDS versus 8 controls. On average, the erythrocyte acetylcholinesterase enzyme activity was also significantly increased (n = 9 SIDS versus 11 controls. CONCLUSIONS: In the present study, it has been shown for the first time that cardiac muscarinic receptor overexpression is associated with SIDS. The increase of acetylcholinesterase enzyme activity appears as a possible regulatory mechanism.
Preferences of Patients for Discussing Sudden Unexpected Death in Epilepsy
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Sūna Normunds
2017-08-01
Full Text Available People with epilepsy have increased mortality rates, which is partially attributed to sudden unexpected death in epilepsy syndrome (SUDEP. Poor seizure control appears to be the strongest SUDEP risk factor. Management of epilepsy and adherence to therapy is critical to seizure control. The belief by caregivers of negative influence caused by being informed about the syndrome is the main reason SUDEP is not disclosed. There are no clear recommendations when to disclose the risk of SUDEP and how much information should be provided. We addressed the preferences of Latvian epilepsy patients for discussing SUDEP as well as awareness of the syndrome. Our study involved 55 epilepsy patients. We found that, as in other studies, our patients were relatively well informed about SUDEP. We found that a considerable proportion of patients preferred to receive information about SUDEP from a general practitioner. We note the belief of patients that the disclosure of SUDEP would either improve or have no effect on the quality of life. We were able to identify groups of patients with a self-reported belief of more frequent expected anxiety and poor adherence to medical treatment. Our data improves the understanding of preferences of patient for discussing the negative aspects of epilepsy.
Phrenic nerves and diaphragms in sudden infant death syndrome.
Weis, J; Weber, U; Schröder, J M; Lemke, R; Althoff, H
1998-01-30
Disturbances of the respiratory system may be an important factor in the cascade of events leading to sudden infant death syndrome (SIDS). Even though the diaphragm is the major respiratory muscle in infants, little is known about alterations of this muscle and of the phrenic nerve in SIDS. In the present study, diaphragms and phrenic nerves of 24 SIDS infants and seven controls were analyzed. Morphometric analysis revealed only slightly larger cross sectional areas of phrenic nerve axons but no increase in myelin sheath thickness in SIDS cases. However, in one SIDS case, myelinated nerve fibre density was severely reduced. Using electron microscopy, several nerve fibres of SIDS infants showed focal accumulations of neurofilaments. Muscle fibre diameters in SIDS diaphragms were significantly larger compared to controls (P fibre ruptures and contracture bands were found. These prominent nonspecific ultrastructural alterations should advise caution in the interpretation of morphometric data. Thus, in some cases exemplified by one case of the present series, decreased density of phrenic nerve myelinated axons might contribute to SIDS. Still, the present results indicate that development of phrenic nerves and diaphragms is not delayed in most SIDS infants.
Sudden infant death syndrome (SIDS): a time lag factor.
Reid, G M
1991-02-01
A time lag factor of about five days has been identified in an increased incidence of SIDS in relation to a cold day. Sudden exposure to chilling appeared to trigger skeletal muscle weakness and renal failure about five days later in a man found to have only 25% of normal carnitine palmitoyl transferase (CPT) activity in biopsied skeletal muscle. White Muscle Disease is a muscular dystrophy in young ruminants which appears about five days after turnout to pasture in the weaned ruminant raised on a diet deficient in vitamin E and selenium (VESD). Pasture has high levels of linoleic and linolenic acid (high PUFA diet) which are modified by developing rumen bacteria. Corbucci investigated the effects of circulatory shock (cardiogenic) on skeletal muscle mitochondrial activity in humans. Cytochrome oxidase activity fell markedly and, in particular, the capacity to oxidase palmitoyl carnitine was greatly reduced. He considered a consequence of this disorder was sequestration of carnitine as acyl carnitine which could not be recycled. Unusual acyl carnitines have been identified in six out of 13 SIDS victims in a USA group. In Finland, researchers identified a rise in SIDS incidence (mostly found in the prone position) after great and rapid temperature changes. Foster found a relationship between 1984 SIDS incidence and the incidence of goitre in World War I troops.
Fragmentation of suddenly heated liquids in ICF reactors. Revision 1
International Nuclear Information System (INIS)
Blink, J.A.; Hoover, W.G.
1985-01-01
Fragmentation of free liquids in Inertial Confinement Fusion reactors could determine the upper bound on reactor pulse rate because increased surface area will enhance the cooling and condensation of coolant ablated by the fusion x rays. Relaxation from the suddenly (neutron) heated state will move a liquid into the negative pressure region under the liquid-vapor P-V dome. The resulting expansion in a diverging geometry will hydrodynamically force the liquid to fragment, with vapor then forming from the new surfaces to fill the cavities. An energy minimization model is used to determine the fragment size that produces the least amount of non-fragment-center-of-mass energy; i.e., the sum of the surface and dilational kinetic energies. This model predicts fragmentation dependence on original system size and amount of isochoric heating as well as liquid density, Grueneisen parameter, surface tension, and sound speed. A two dimensional molecular dynamics code was developed to test the model at a microscopic scale for the Lennard-Jones fluid with its two adjustable constants chosen to represent lithium
The initial phase of sudden releases of superheated liquid
International Nuclear Information System (INIS)
Schmidli, J.; Yadigaroglu, G.
1994-01-01
Series of experiments were conducted with refrigerants-114, -12, propane and butane to investigate the initial phase of sudden releases of superheated liquids due to the catastrophic failure of the vessel containing them. The experiments were initiated by shattering spherical flasks of 100 to 2000 ml containing the liquefied, pressurized gases. The variable parameters were the initial superheat, the filling level, the height of the flask above ground, and the relative humidity of the surrounding air. It was found that the initial flashing process is not determined by homogeneous nucleation, but rather by surface instabilities which lead to an evaporation wave traveling from the initial surface towards the center of the released mass. Cloud shape and expansion velocity could be determined from high speed recordings covering the initial stage of the release during which gravity has no influence. When the internal energy was sufficient, it was observed that the expanding droplet/vapor cloud initially propagated spherically with a constant expansion velocity, until Rayleigh-Taylor type instabilities appeared at its surface. Information about the pool which can be formed on the ground, the pressure decay within the flask, the droplet size, and the cloud temperature was collected. The experimental findings for the expansion velocity, as well as for the pool fraction, were the base for a nondimensional analysis leading to correlations which describe the initial phase of such releases and can be used to define the ''source term'' for turbulent dispersion models. (author) 5 figs., 1 tab., 15 refs
Risk factors for sudden cardiac death among patients with schizophrenia.
Hou, Ping-Yi; Hung, Galen Chin-Lun; Jhong, Jia-Rong; Tsai, Shang-Ying; Chen, Chiao-Chicy; Kuo, Chian-Jue
2015-10-01
Patients with schizophrenia suffer from excessive premature mortality, and sudden cardiac death (SCD) is receiving growing attention as a potential cause. The present study investigated the incidence of SCD and its risk factors in a large schizophrenia cohort. We enrolled a consecutive series of 8264 patients diagnosed with schizophrenia (according to DSM-III-R and DSM-IV criteria) who were admitted to a psychiatric center in northern Taiwan from January 1, 1985 through December 31, 2008. By linking with national mortality database, 64 cases of SCD were identified. The standardized mortality ratio (SMR) for SCD was estimated. The cases were matched with controls randomly selected using risk-set sampling in a 1:2 ratio. A standardized chart review process was used to collect socio-demographic and clinical characteristics and the prescribed drugs for each study subject. Multivariate conditional logistic regression analysis was used to identify correlates of SCD at the index admission and the latest admission. The SMR for SCD was 4.5. For the clinical profiles at the index admission, physical disease (adjusted risk ratio [aRR]=2.91, Prisk of SCD. Regarding the latest admission, electrocardiographic abnormalities (aRR=5.46, Prisk for SCD. Consistently, aggressive behaviors (aRR=3.26, Prisk as well. Apart from cardiovascular profiles and antipsychotics, physical aggression is a crucial risk factor that deserves ongoing work for clarifying the mechanisms mediating SCD in schizophrenia. Copyright © 2015 Elsevier B.V. All rights reserved.
A “wear and tear” hypothesis to explain Sudden Infant Death Syndrome (SIDS
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Eran Elhaik
2016-10-01
Full Text Available Sudden Infant Death Syndrome (SIDS is the leading cause of death in USA infants under one year of age accounting for approximately 2,700 deaths per year. Although formally SIDS dates back at least 2,000 years and was even mentioned in the Hebrew Bible (Kings 3:19 its etiology remains unexplained prompting the CDC to initiate a sudden unexpected infant death case registry in 2010. Due to their total dependence, the ability of the infant to allostatically regulate stressors and stress responses shaped by genetic and environmental factors is severely constrained. We propose that SIDS is the result of cumulative painful, stressful, or traumatic exposures that begin in utero and tax neonatal regulatory systems incompatible with allostasis. We also identify several putative biochemical mechanisms involved in SIDS. We argue that the important characteristics of SIDS, namely male predominance (60:40, the significantly different SIDS rate in USA Hispanics (80% lower compared to whites, 50% of cases occurring between 7.6 and 17.6 weeks after birth with only 10% after 24.7 weeks, and seasonal variation with most cases occurring during winter, are all associated with common environmental stressors, such as neonatal circumcision and seasonal illnesses. We predict that neonatal circumcision is associated with hypersensitive to pain and decreased heart rate variability which increase the risk for SIDS. We also predict that neonatal male circumcision will account for the SIDS gender bias and that cultures that practice high male circumcision rates, like USA whites, will have higher SIDS rates compared to cultures with lower circumcision rates. SIDS rates will also be higher in USA states where Medicaid covers circumcision and lower among cultures that do not practice neonatal circumcision and/or cannot afford to pay for circumcision. We last predict that winter-born premature infants who are circumcised will be at higher risk of SIDS compared to infants who
Saito, Mari; Yamagata, Takanori; Matsumoto, Ayumi; Shiba, Yusuke; Nagashima, Masako; Taniguchi, Shuhei; Jimbo, Eriko; Momoi, Mariko Y
2014-01-01
Deletion of the monoamine oxidase (MAO)-A and MAO-B was detected in two male siblings and in their mother. The approximately 800-kb deletion, extending from about 43.0MB to 43.8MB, was detected by array comparative genomic hybridization analysis. The MAOA and MAOB genes were included in the deletion, but the adjacent Norrie disease gene, NDP, was not deleted. The boys had short stature, hypotonia, severe developmental delays, episodes of sudden loss of muscle tone, exiting behavior, lip-smacking and autistic features. The serotonin levels in their cerebrospinal fluid were extremely elevated. Another set of siblings with this deletion was reported previously. We propose recognition of MAOA/B deletion syndrome as a distinct disorder. Copyright © 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.
The centrifugal sudden distorted wave method for chemical reactions: Application to Cl+HCl → ClH+Cl
International Nuclear Information System (INIS)
Amaee, B.; Connor, J.N.L.; Schatz, G.C.
1987-01-01
The authors describe a method for calculating cross sections for atom plus diatom reactive collisions based on the centrifugal sudden distorted wave (CSDW) approximation. This method is nearly exact at low energies where reactive cross sections are small. Representative CPU times are given for applications of CSDW method to the Cl + HCl → ClH + Cl reaction using CDC 7600, Cyber 176, Cyber 205, Cray XMP and Cray 2 computers. Calculations show that the product HCl molecule is highly rotationally excited, (receiving 40-50% of the available energy) and that the shape of the product rotational distribution is nearly independent of reagent rotational state. The authors also calculated product differential cross sections and find them to be backward peaked at low energies
Foley, Jeannine; Burnham, Veronica; Tedoldi, Meghan; Danial, Nika N; Yellen, Gary
2018-01-01
Metabolic alteration, either through the ketogenic diet (KD) or by genetic alteration of the BAD protein, can produce seizure protection in acute chemoconvulsant models of epilepsy. To assess the seizure-protective role of knocking out (KO) the Bad gene in a chronic epilepsy model, we used the Kcna1 -/- model of epilepsy, which displays progressively increased seizure severity and recapitulates the early death seen in sudden unexplained death in epilepsy (SUDEP). Beginning on postnatal day 24 (P24), we continuously video monitored Kcna1 -/- and Kcna1 -/- Bad -/- double knockout mice to assess survival and seizure severity. We found that Kcna1 -/- Bad -/- mice outlived Kcna1 -/- mice by approximately 2 weeks. Kcna1 -/- Bad -/- mice also spent significantly less time in seizure than Kcna1 -/- mice on P24 and the day of death, showing that BadKO provides seizure resistance in a genetic model of chronic epilepsy. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.
Al-Khatib, Sana M; Sanders, Gillian D; Bigger, J Thomas; Buxton, Alfred E; Califf, Robert M; Carlson, Mark; Curtis, Anne; Curtis, Jeptha; Fain, Eric; Gersh, Bernard J; Gold, Michael R; Haghighi-Mood, Ali; Hammill, Stephen C; Healey, Jeff; Hlatky, Mark; Hohnloser, Stefan; Kim, Raymond J; Lee, Kerry; Mark, Daniel; Mianulli, Marcus; Mitchell, Brent; Prystowsky, Eric N; Smith, Joseph; Steinhaus, David; Zareba, Wojciech
2007-06-01
Accurate and timely prediction of sudden cardiac death (SCD) is a necessary prerequisite for effective prevention and therapy. Although the largest number of SCD events occurs in patients without overt heart disease, there are currently no tests that are of proven predictive value in this population. Efforts in risk stratification for SCD have focused primarily on predicting SCD in patients with known structural heart disease. Despite the ubiquity of tests that have been purported to predict SCD vulnerability in such patients, there is little consensus on which test, in addition to the left ventricular ejection fraction, should be used to determine which patients will benefit from an implantable cardioverter defibrillator. On July 20 and 21, 2006, a group of experts representing clinical cardiology, cardiac electrophysiology, biostatistics, economics, and health policy were joined by representatives of the US Food and Drug administration, Centers for Medicare Services, Agency for Health Research and Quality, the Heart Rhythm Society, and the device and pharmaceutical industry for a round table meeting to review current data on strategies of risk stratification for SCD, to explore methods to translate these strategies into practice and policy, and to identify areas that need to be addressed by future research studies. The meeting was organized by the Duke Center for the Prevention of SCD at the Duke Clinical Research Institute and was funded by industry participants. This article summarizes the presentations and discussions that occurred at that meeting.
Investigation of neutrophil-to-lymphocyte ratio and mean platelet volume in sudden hearing loss,
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Rauf Oguzhan Kum
2015-12-01
Full Text Available ABSTRACT INTRODUCTION: Several theories attempt to explain the pathophysiology of sudden hearing loss. OBJECTIVE: The objective of this study was to investigate the possible role of inflammation and atherothrombosis in sudden hearing loss patients through the neutrophil-to-lymphocyte ratio and mean platelet volume. METHODS: Study design - retrospective cross-sectional historical cohort. This study was conducted on two groups: one with 59 individuals diagnosed with sudden hearing loss, and other with 59 healthy individuals with the same characteristics of gender and age distribution, neutrophil-to-lymphocyte ratio and mean platelet volume levels were measured in patients diagnosed with sudden hearing loss as well as in the control group, and it was verified whether these results interfered for a better or worse prognosis with treatment of sudden deafness. RESULTS: Neutrophil-to-lymphocyte ratio levels are much higher in patients diagnosed with sudden hearing loss compared to the control group. Similarly, mean levels of neutrophil-to-lymphocyte ratio are higher in non-recovered versus recovered patients (p = 0.001. However, we could not find a correlation with mean platelet volume levels (p > 0.05. CONCLUSION: Neutrophil-to-lymphocyte ratio is a quick and reliable indicator regarding diagnosis and prognosis of sudden hearing loss; on the other hand, mean platelet volume may be considered a less important indicator in this aspect.
Sudden gains in Cognitive Therapy and Interpersonal Psychotherapy for adult depression.
Lemmens, Lotte H J M; DeRubeis, Robert J; Arntz, Arnoud; Peeters, Frenk P M L; Huibers, Marcus J H
2016-02-01
We examined the rates, baseline predictors and clinical impact of sudden gains in a randomized comparison of individual Cognitive Therapy (CT) and Interpersonal Psychotherapy (IPT) for adult depression. 117 depressed outpatients received 16-20 sessions of either CT or IPT. Session-by-session symptom severity was assessed using the BDI-II. Sudden gains were examined using the original criteria as defined by Tang and DeRubeis (1999b). Furthermore, we examined whether the duration of the between-session interval at which sudden gains were recorded affected the results. There were significantly more patients with sudden gains in CT (42.2%) as compared to IPT (24.5%). The difference appeared to be driven by the criterion representing the stability of the gain. No between-group differences were found with regard to the magnitude, timing and predictors of the gains. Those with sudden gains were less depressed at post-treatment and follow-up. After controlling for the duration of the between-session interval, the difference in rates between the two conditions became a non-significant trend. Other sudden gains characteristics were similar to those observed when allowing for longer intervals as well. The current study indicates differences in occurrence of sudden gains in two treatment modalities that overall showed similar results, which might reflect different mechanisms of change. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Riffat Mehboob
2017-07-01
Full Text Available Sudden perinatal death that includes the victims of sudden infant death syndrome, sudden intrauterine death syndrome, and stillbirth are heartbreaking events in the life of parents. Most of the studies about sudden perinatal death were reported from Italy, highlighting two main etiological factors: prone sleeping position and smoking. Other probable contributory factors are prematurity, male gender, lack of breastfeeding, respiratory tract infections, use of pacifiers, infant botulism, extensive use of pesticides and insecticides, etc. However, extensive studies across the world are required to establish the role of these factors in a different subset of populations. Previous studies confirmed the widely accepted hypothesis that neuropathology of the brainstem is one of the main cause of sudden perinatal death. This study is an effort to summarize the neuropathological evaluation of the brainstems and their association to sudden perinatal death. Brainstem nuclei in vulnerable infants undergo certain changes that may alter the sleep arousal cycle, cardiorespiratory control, and ultimately culminate in death. This review focuses on the roles of different brainstem nuclei, their pathologies, and the established facts in this regard in terms of it’s link to such deaths. This study will also help to understand the role of brainstem nuclei in controlling the cardiorespiratory cycles in sudden perinatal death and may provide a better understanding to resolve the mystery of these deaths in future. It is also found that a global initiative to deal with perinatal death is required to facilitate the diagnosis and prevention in developed and as well as developing countries.
Trajectory averaging for stochastic approximation MCMC algorithms
Liang, Faming
2010-01-01
to the stochastic approximation Monte Carlo algorithm [Liang, Liu and Carroll J. Amer. Statist. Assoc. 102 (2007) 305-320]. The application of the trajectory averaging estimator to other stochastic approximationMCMC algorithms, for example, a stochastic
Reduction of Linear Programming to Linear Approximation
Vaserstein, Leonid N.
2006-01-01
It is well known that every Chebyshev linear approximation problem can be reduced to a linear program. In this paper we show that conversely every linear program can be reduced to a Chebyshev linear approximation problem.
QT prolongation and sudden cardiac death risk in hypertrophic cardiomyopathy.
Patel, Salma I; Ackerman, Michael J; Shamoun, Fadi E; Geske, Jeffrey B; Ommen, Steve R; Love, William T; Cha, Stephen S; Bos, Johan M; Lester, Steven J
2018-03-07
Risk assessment for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) remains complex. The goal of this study was to assess electrocardiogram (ECG)-derived risk factors on SCD in a large HCM population Methods: Retrospective review of adults with HCM evaluated at Mayo Clinic, Rochester, MN from 1 December 2002 to 31 December 2012 was performed. Data inclusive of ECG and 24-hour ambulatory Holter monitor were assessed. SCD events were documented by ventricular fibrillation (VF) noted on implantable cardioverter defibrillator (ICD), or appropriate VT or VF-terminating ICD shock. Overall, 1615 patients (mean age 53.7 ± 15.2 years; 943 males, 58.4%) were assessed, with mean follow-up 2.46 years and 110 SCD events. Via logistic regression (n = 820), the odds of SCD increased with increasing number of conventional risk factors. With one risk factor the OR was 4.88 (p 450 to this logistic regression model had OR 1.722 (p = .04, CI 1.01-2.937) to predict SCD. QTc ≥ 450 was a significant predictor for death (HR 1.88, p = .021, CI 1.10-3.20). There was no correlation between sinus bradycardia, sinus tachycardia, first degree AV block, atrial fibrillation, left bundle branch block, right bundle branch block, premature atrial complexes, premature ventricular complexes, supraventricular tachycardia, PR interval, QRS interval and SCD. Prolonged QTc was a risk factor for SCD and death even when controlling for typical risk factors.
Sudden Death Phenomenon While Bathing in Japan - Mortality Data.
Suzuki, Masaru; Shimbo, Takuro; Ikaga, Toshiharu; Hori, Shingo
2017-07-25
Bath-related sudden cardiac arrest frequently occurs in Japan, but the mortality data have not been sufficiently reported.Methods and Results:This prospective cross-sectional observational study was conducted in the Tokyo Metropolis, Saga Prefecture and Yamagata Prefecture between October 2012 and March 2013 (i.e., in winter). We investigated the data for all occurrences in these areas for which the emergency medical system needed to be activated because of an accident or acute illness related to bathing. Emergency personnel enrolled the event when activation of the emergency medical system was related to bathing. Of the 4,599 registered bath-related events, 1,527 (33%) were identified as bath-related cardiac arrest events. Crude mortality (no. deaths per 100,000) during the observational period was 10.0 in Tokyo, 11.6 in Yamagata and 8.5 in Saga. According to the mortality data for age and sex, the estimated number of bath-related deaths nationwide was 13,369 in winter, for the 6 months from October (95% CI: 10,862-16,887). Most cardiac arrest events occurred in tubs filled with water with the face submerged in the water. This suggests that drowning plays a crucial role in the etiology of such phenomena. The estimated nationwide number of deaths was 13,369 (95% CI: 10,862-16,887) in winter, for the 6 months from October. Crude mortality during the winter season was 10.0 in Tokyo, 11.6 in Yamagata and 8.5 in Saga.
Vertigo with sudden hearing loss: audio-vestibular characteristics.
Pogson, Jacob M; Taylor, Rachael L; Young, Allison S; McGarvie, Leigh A; Flanagan, Sean; Halmagyi, G Michael; Welgampola, Miriam S
2016-10-01
Acute vertigo with sudden sensorineural hearing loss (SSNHL) is a rare clinical emergency. Here, we report the audio-vestibular test profiles of 27 subjects who presented with these symptoms. The vestibular test battery consisted of a three-dimensional video head impulse test (vHIT) of semicircular canal function and recording ocular and cervical vestibular-evoked myogenic potentials (oVEMP, cVEMP) to test otolith dysfunction. Unlike vestibular neuritis, where the horizontal and anterior canals with utricular function are more frequently impaired, 74 % of subjects with vertigo and SSNHL demonstrated impairment of the posterior canal gain (0.45 ± 0.20). Only 41 % showed impairment of the horizontal canal gains (0.78 ± 0.27) and 30 % of the anterior canal gains (0.79 ± 0.26), while 38 % of oVEMPs [asymmetry ratio (AR) = 41.0 ± 41.3 %] and 33 % of cVEMPs (AR = 47.3 ± 41.2 %) were significantly asymmetrical. Twenty-three subjects were diagnosed with labyrinthitis/labyrinthine infarction in the absence of evidence for an underlying pathology. Four subjects had a definitive diagnosis [Ramsay Hunt Syndrome, vestibular schwannoma, anterior inferior cerebellar artery (AICA) infarction, and traction injury]. Ischemia involving the common-cochlear or vestibulo-cochlear branches of the labyrinthine artery could be the simplest explanation for vertigo with SSNHL. Audio-vestibular tests did not provide easy separation between ischaemic and non-ischaemic causes of vertigo with SSNHL.
Sudden infant death syndrome and the genetics of inflammation
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Linda eFerrante
2015-02-01
Full Text Available Several studies report signs of slight infection prior to death in cases of sudden infant death syndrome (SIDS. Based on this, a hypothesis of an altered immunological homeostasis has been postulated. The cytokines are important cellular mediators that are crucial for infant health by regulating cell activity during the inflammatory process. The pro-inflammatory cytokines favor inflammation; the most important of these are IL-1α, IL-1β, IL-6, IL-8, IL-12, IL-18, TNF-α and IFN-γ. These cytokines are controlled by the anti-inflammatory cytokines. This is accomplished by reducing the pro-inflammatory cytokine production, and thus counteracts their biological effect. The major anti-inflammatory cytokines are interleukin 1 receptor antagonist (IL-1ra, IL-4, IL-10, IL-11, and IL-13. The last decade there has been focus on genetic studies within genes that are important for the immune system, for SIDS with a special interest of the genes encoding the cytokines. This is because the cytokine genes are considered to be the genes most likely to explain the vulnerability to infection, and several studies have investigated these genes in an attempt to uncover associations between SIDS and different genetic variants. So far the genes encoding IL-1, IL-6, IL-10 and TNF-α are the most investigated within SIDS research, and several studies indicates associations between specific variants of these genes and SIDS. Taken together this may indicate that in at least a subset of SIDS predisposing genetic variants of the immune genes are involved. However, the immune system and the cytokine network are complex, and more studies are needed in order to better understand the interplay between different genetic variations and how this may contribute to an unfavorable immunological response.
Sudden unexpected death in infancy: place and time of death.
Glasgow, J F T; Thompson, A J; Ingram, P J
2006-01-01
In recent years, many babies who die of Sudden Unexpected Death in Infancy (SUDI) in Northern Ireland are found dead in bed--i.e. co-sleeping--with an adult. In order to assess its frequency autopsy reports between April 1996 and August 2001 were reviewed and linked to temporal factors. The day and month of death, and the place where the baby was found were compared to a reference population of infant deaths between one week of age and the second birthday. Although the rate of SUDI was lower than the UK average, 43 cases of SUDI were identified, and two additional deaths with virtually identical autopsy findings that were attributed to asphyxia caused by suffocation due to overlaying. Thirty-two of the 45 (71%) were less than four months of age. In 30 of the 45 cases (67%) the history stated that the baby was bed sharing with others; 19 died sleeping in an adult bed, and 11 on a sofa or armchair. In 16 of the 30 (53%) there were at least two other people sharing the sleeping surface, and in one case, three. SUDI was twice as frequent at weekends (found dead Saturday-Monday mornings) compared to weekdays (psharing a place of sleep per se may not increase the risk of death, our findings may be linked to factors such as habitual smoking, consumption of alcohol or illicit drugs as reported in case-control studies. In advising parents on safer childcare practices, health professionals must be knowledgeable of current research and when, for example, giving advice on co-sleeping this needs to be person-specific cognisant of the risks within a household. New and better means of targeting such information needs to be researched if those with higher risk life-styles are to be positively influenced.
Clinical Study on 136 Children with Sudden Sensorineural Hearing Loss.
Li, Feng-Jiao; Wang, Da-Yong; Wang, Hong-Yang; Wang, Li; Yang, Feng-Bo; Lan, Lan; Guan, Jing; Yin, Zi-Fang; Rosenhall, Ulf; Yu, Lan; Hellstrom, Sten; Xue, Xi-Jun; Duan, Mao-Li; Wang, Qiu-Ju
2016-04-20
The prevalence of sudden sensorineural hearing loss in children (CSSNHL) is consistently increasing. However, the pathology and prognosis of CSSNHL are still poorly understood. This retrospective study evaluated clinical characteristics and possible associated factors of CSSNHL. One hundred and thirty-six CSSNHL patients treated in Department of Otolaryngology-Head and Neck Surgery and Institute of Otolaryngology at Chinese PLA General Hospital between July 2008 and August 2015 were included in this study. These patients were analyzed for clinical characteristics, audiological characteristics, laboratory examinations, and prognostic factors. Among the 136 patients (151 ears), 121 patients (121 ears, 80.1%) were diagnosed with unilaterally CSSNHL, and 15 patients (30 ears, 19.9%) with bilateral CSSNHL. The complete recovery rate of CSSNHL was 9.3%, and the overall recovery rate was 37.7%. We found that initial degree of hearing loss, onset of treatment, tinnitus, the ascending type audiogram, gender, side of hearing loss, the recorded auditory brainstem response (ABR), and distortion product otoacoustic emissions (DPOAEs) had prognostic significance. Age, ear fullness, and vertigo had no significant correlation with recovery. Furthermore, the relevant blood tests showed 30.8% of the children had abnormal white blood cell (WBC) counts, 22.1% had elevated homocysteine levels, 65.8% had high alkaline phosphatase (ALP), 33.8% had high IgE antibody levels, and 86.1% had positive cytomegalovirus (CMV) IgG antibodies. CSSNHL commonly occurs unilaterally and results in severe hearing loss. Initial severe hearing loss and bilateral hearing loss are negative prognostic factors for hearing recovery, while positive prognostic factors include tinnitus, gender, the ascending type audiogram, early treatment, identifiable ABR waves, and DPOAEs. Age, vertigo, and ear fullness are not correlated with the recovery. Some serologic indicators, including the level of WBC, platelet
Sudden sensorineural hearing loss in children: Etiology, management, and outcome.
Pitaro, Jacob; Bechor-Fellner, Avital; Gavriel, Haim; Marom, Tal; Eviatar, Ephraim
2016-03-01
Pediatric sudden sensorineural hearing loss (SSNHL) is uncommon, and the current guidelines for its management refer to adults. Our objective was to review cases of SSNHL in children and examine their etiologies, management, and outcome. We performed a retrospective chart review of all children under the age of 18 years treated for SSNHL between January 2003 and September 2014. Data recorded included age, gender, symptoms, onset of hearing loss, audiometric results, diagnostic studies, treatment, and outcome. Nineteen children were included. Mean age was 14 years (range 7-18 years). Male: female ratio was 9:10. Degree of hearing loss varied from mild to profound across the tested frequencies. Most common accompanying symptom was tinnitus. Serologic tests demonstrated recent Epstein-Barr virus infection in one patient and previous cytomegalovirus infection in six patients. Imaging studies included computed tomography scan (n=3) and/or magnetic resonance imaging (n=12). All imaging studies did not demonstrate any pathology. Treatment included systemic steroids in 19 (100%) children and intratympanic steroids in eight (42%). Hearing completely improved in three (16%) children, partially improved in nine (47%), and there was no improvement in six (32%). One child was lost to follow-up. Viral infection was a common finding in children with SSNHL and no pathological changes were demonstrated on imaging studies. In most patients (63%), hearing improvement was observed. Intratympanic steroid injection can benefit these children. Further studies are required to investigate the etiologies and establish guidelines for the management of SSNHL in children. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Maternal and obstetrical predictors of sudden infant death syndrome (SIDS).
Friedmann, Isabel; Dahdouh, Elias M; Kugler, Perlyne; Mimran, Gracia; Balayla, Jacques
2017-10-01
Public Health initiatives, such as the "Safe to Sleep" campaign, have traditionally targeted infants' risk factors for the prevention of Sudden Infant Death Syndrome (SIDS). However, controversy remains regarding maternal and obstetrical risk factors for SIDS. In our study, we sought out to determine both modifiable and non-modifiable obstetrical and maternal risk factors associated with SIDS. We conducted a population-based cohort study using the CDC's Linked Birth-Infant Death data from the United States for the year 2010. The impact of several obstetrical and maternal risk factors on the risk of overall infant mortality and SIDS was estimated using unconditional regression analysis, adjusting for relevant confounders. Our cohort consisted of 4,007,105 deliveries and 24,174 infant deaths during the first year of life, of which 1991 (8.2%) were due to SIDS. Prominent risk factors for SIDS included (OR [95% CI]): black race, 1.89 [1.68-2.13]; maternal smoking, 3.56 [3.18-3.99]; maternal chronic hypertension, 1.73 [1.21-2.48]; gestational hypertension, 1.51 [1.23-1.87]; premature birth <37 weeks, 2.16 [1.82-2.55]; IUGR, 2.46 [2.14-2.82]; and being a twin, 1.81 [1.43-2.29], p < 0.0001. Relative to a cohort of infants who died of other causes, risk factors with a predilection for SIDS were maternal smoking, 2.48 [2.16-2.83] and being a twin, 1.52 [1.21-1.91], p < 0.0001. Conclusions for practice: While certain socio-demographic and gestational characteristics are important risk factors, maternal smoking remains the strongest prenatal modifiable risk factor for SIDS. We recommend the continuation of Public Health initiatives that promote safe infant sleeping practices and smoking cessation during and after pregnancy.
Some relations between entropy and approximation numbers
Institute of Scientific and Technical Information of China (English)
郑志明
1999-01-01
A general result is obtained which relates the entropy numbers of compact maps on Hilbert space to its approximation numbers. Compared with previous works in this area, it is particularly convenient for dealing with the cases where the approximation numbers decay rapidly. A nice estimation between entropy and approximation numbers for noncompact maps is given.
Axiomatic Characterizations of IVF Rough Approximation Operators
Directory of Open Access Journals (Sweden)
Guangji Yu
2014-01-01
Full Text Available This paper is devoted to the study of axiomatic characterizations of IVF rough approximation operators. IVF approximation spaces are investigated. The fact that different IVF operators satisfy some axioms to guarantee the existence of different types of IVF relations which produce the same operators is proved and then IVF rough approximation operators are characterized by axioms.
An approximation for kanban controlled assembly systems
Topan, E.; Avsar, Z.M.
2011-01-01
An approximation is proposed to evaluate the steady-state performance of kanban controlled two-stage assembly systems. The development of the approximation is as follows. The considered continuous-time Markov chain is aggregated keeping the model exact, and this aggregate model is approximated
Operator approximant problems arising from quantum theory
Maher, Philip J
2017-01-01
This book offers an account of a number of aspects of operator theory, mainly developed since the 1980s, whose problems have their roots in quantum theory. The research presented is in non-commutative operator approximation theory or, to use Halmos' terminology, in operator approximants. Focusing on the concept of approximants, this self-contained book is suitable for graduate courses.
[Three good reasons to perform a postmortem examination in all cases of juvenile sudden death].
d'Amati, Giulia; di Gioia, Cira R T; Silenzi, Paola F; Gallo, Pietro
2009-04-01
The aim of this review is to underline the reasons why a post-mortem examination has to be performed in all cases of juvenile sudden death. Sudden death in children and young adults can be caused by potentially heritable cardiovascular disorders and fatal outcome is often the first symptom in apparently healthy subjects. In these cases, a careful autopsy, performed according to a standardized protocol, becomes the sole diagnostic tool to guide clinical and molecular genetic family screening and to adopt the proper therapeutic and preventive strategies. Thus, a post-mortem examination is a fundamental part of a multidisciplinary approach to the issue of juvenile sudden death.
Numerical Investigation of Pressure Losses in Axisymmetric Sudden Expansion with a Chamfer
Energy Technology Data Exchange (ETDEWEB)
Bae, Youngmin; Kim, Youngin; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-05-15
In this paper, the pressure losses through axisymmetric sudden expansions with a chamfer are analyzed by means of numerical simulation, with an emphasis on the effect of the Reynolds number. In this study, we investigate numerically the turbulent flow in axisymmetric sudden expansions having a slight chamfer on the edge. With the aim of investigating the impact of Reynolds number on the expansion losses in a time-averaged sense, an extensive set of simulations is carried out. On the basis of numerical results, we also propose a general correlation to estimate the local loss coefficient in sudden expansions with a chamfer.
Numerical Investigation of Pressure Losses in Axisymmetric Sudden Expansion with a Chamfer
International Nuclear Information System (INIS)
Bae, Youngmin; Kim, Youngin; Kim, Keung Koo
2014-01-01
In this paper, the pressure losses through axisymmetric sudden expansions with a chamfer are analyzed by means of numerical simulation, with an emphasis on the effect of the Reynolds number. In this study, we investigate numerically the turbulent flow in axisymmetric sudden expansions having a slight chamfer on the edge. With the aim of investigating the impact of Reynolds number on the expansion losses in a time-averaged sense, an extensive set of simulations is carried out. On the basis of numerical results, we also propose a general correlation to estimate the local loss coefficient in sudden expansions with a chamfer
Analysis of corrections to the eikonal approximation
Hebborn, C.; Capel, P.
2017-11-01
Various corrections to the eikonal approximations are studied for two- and three-body nuclear collisions with the goal to extend the range of validity of this approximation to beam energies of 10 MeV/nucleon. Wallace's correction does not improve much the elastic-scattering cross sections obtained at the usual eikonal approximation. On the contrary, a semiclassical approximation that substitutes the impact parameter by a complex distance of closest approach computed with the projectile-target optical potential efficiently corrects the eikonal approximation. This opens the possibility to analyze data measured down to 10 MeV/nucleon within eikonal-like reaction models.
Mapping moveout approximations in TI media
Stovas, Alexey; Alkhalifah, Tariq Ali
2013-01-01
Moveout approximations play a very important role in seismic modeling, inversion, and scanning for parameters in complex media. We developed a scheme to map one-way moveout approximations for transversely isotropic media with a vertical axis of symmetry (VTI), which is widely available, to the tilted case (TTI) by introducing the effective tilt angle. As a result, we obtained highly accurate TTI moveout equations analogous with their VTI counterparts. Our analysis showed that the most accurate approximation is obtained from the mapping of generalized approximation. The new moveout approximations allow for, as the examples demonstrate, accurate description of moveout in the TTI case even for vertical heterogeneity. The proposed moveout approximations can be easily used for inversion in a layered TTI medium because the parameters of these approximations explicitly depend on corresponding effective parameters in a layered VTI medium.
Analytical approximation of neutron physics data
International Nuclear Information System (INIS)
Badikov, S.A.; Vinogradov, V.A.; Gaj, E.V.; Rabotnov, N.S.
1984-01-01
The method for experimental neutron-physical data analytical approximation by rational functions based on the Pade approximation is suggested. It is shown that the existence of the Pade approximation specific properties in polar zones is an extremely favourable analytical property essentially extending the convergence range and increasing its rate as compared with polynomial approximation. The Pade approximation is the particularly natural instrument for resonance curve processing as the resonances conform to the complex poles of the approximant. But even in a general case analytical representation of the data in this form is convenient and compact. Thus representation of the data on the neutron threshold reaction cross sections (BOSPOR constant library) in the form of rational functions lead to approximately twenty fold reduction of the storaged numerical information as compared with the by-point calculation at the same accWracy
A unified approach to the Darwin approximation
International Nuclear Information System (INIS)
Krause, Todd B.; Apte, A.; Morrison, P. J.
2007-01-01
There are two basic approaches to the Darwin approximation. The first involves solving the Maxwell equations in Coulomb gauge and then approximating the vector potential to remove retardation effects. The second approach approximates the Coulomb gauge equations themselves, then solves these exactly for the vector potential. There is no a priori reason that these should result in the same approximation. Here, the equivalence of these two approaches is investigated and a unified framework is provided in which to view the Darwin approximation. Darwin's original treatment is variational in nature, but subsequent applications of his ideas in the context of Vlasov's theory are not. We present here action principles for the Darwin approximation in the Vlasov context, and this serves as a consistency check on the use of the approximation in this setting
Mapping moveout approximations in TI media
Stovas, Alexey
2013-11-21
Moveout approximations play a very important role in seismic modeling, inversion, and scanning for parameters in complex media. We developed a scheme to map one-way moveout approximations for transversely isotropic media with a vertical axis of symmetry (VTI), which is widely available, to the tilted case (TTI) by introducing the effective tilt angle. As a result, we obtained highly accurate TTI moveout equations analogous with their VTI counterparts. Our analysis showed that the most accurate approximation is obtained from the mapping of generalized approximation. The new moveout approximations allow for, as the examples demonstrate, accurate description of moveout in the TTI case even for vertical heterogeneity. The proposed moveout approximations can be easily used for inversion in a layered TTI medium because the parameters of these approximations explicitly depend on corresponding effective parameters in a layered VTI medium.
An Approximate Approach to Automatic Kernel Selection.
Ding, Lizhong; Liao, Shizhong
2016-02-02
Kernel selection is a fundamental problem of kernel-based learning algorithms. In this paper, we propose an approximate approach to automatic kernel selection for regression from the perspective of kernel matrix approximation. We first introduce multilevel circulant matrices into automatic kernel selection, and develop two approximate kernel selection algorithms by exploiting the computational virtues of multilevel circulant matrices. The complexity of the proposed algorithms is quasi-linear in the number of data points. Then, we prove an approximation error bound to measure the effect of the approximation in kernel matrices by multilevel circulant matrices on the hypothesis and further show that the approximate hypothesis produced with multilevel circulant matrices converges to the accurate hypothesis produced with kernel matrices. Experimental evaluations on benchmark datasets demonstrate the effectiveness of approximate kernel selection.
Bounded-Degree Approximations of Stochastic Networks
Energy Technology Data Exchange (ETDEWEB)
Quinn, Christopher J.; Pinar, Ali; Kiyavash, Negar
2017-06-01
We propose algorithms to approximate directed information graphs. Directed information graphs are probabilistic graphical models that depict causal dependencies between stochastic processes in a network. The proposed algorithms identify optimal and near-optimal approximations in terms of Kullback-Leibler divergence. The user-chosen sparsity trades off the quality of the approximation against visual conciseness and computational tractability. One class of approximations contains graphs with speci ed in-degrees. Another class additionally requires that the graph is connected. For both classes, we propose algorithms to identify the optimal approximations and also near-optimal approximations, using a novel relaxation of submodularity. We also propose algorithms to identify the r-best approximations among these classes, enabling robust decision making.
Heijnen, J.J.; Daran, J.M.; Pronk, J.T.; Daran-Lapujade, P.; Knijnenburg, T.A.; Ras, C.; Ten Pierick, A.; Akmering, M.J.; Van Winden, W.A.; Kresnowati, M.T.
2006-01-01
Within the first 5 min after a sudden relief from glucose limitation, Saccharomyces cerevisiae exhibited fast changes of intracellular metabolite levels and a major transcriptional reprogramming. Integration of transcriptome and metabolome data revealed tight relationships between the changes at
Acute otitis media associated bilateral sudden hearing loss: case report and literature review.
Smith, A; Gutteridge, I; Elliott, D; Cronin, M
2017-07-01
Sudden sensorineural hearing loss is a rare otological condition with potential for dire outcomes including permanent hearing loss. Although the majority of cases are deemed idiopathic, bilateral sudden sensorineural hearing loss represents a rare subset typically related to systemic conditions, with higher morbidity and mortality. A controversial association with acute otitis media has been reported, with few bilateral cases published in the literature. A very rare case of bilateral sudden sensorineural hearing loss associated with acute otitis media is described, with a review of the literature. The limited evidence available suggests that acute otitis media with tinnitus and/or bacterial pathology may have an increased risk of sudden sensorineural hearing loss, which is consistent with the case described. Although there is no sufficiently powered published evidence to provide definitive treatment guidelines, the literature reviewed suggests that early myringotomy and antibiotics may greatly improve treatment outcomes.
Decomposition and N cycling changes in redwood forests caused by sudden oak death
Richard C. Cobb; David M. Rizzo
2012-01-01
Phytophthora ramorum is an emergent pathogen in redwood forests which causes the disease sudden oak death. Although the disease does not kill coast redwood (Sequoia sempervirens), extensive and rapid mortality of tanoak (Notholithocarpus densiflorus) has removed this...
Sudden unexplained death in childhood. An audit of the quality of Autopsy reporting
LENUS (Irish Health Repository)
Treacy, A
2013-03-01
Cases of sudden unexplained death in childhood (SUDC) in Ireland in children aged >1year and <5 years were examined in order to assess the quality of autopsy reporting. All SUDC cases are notified to and documented by the National Sudden Infant Death Register (NSIDR) in Ireland along with all cases of sudden infant death syndrome (SIDS) referring to sudden infant deaths less than one year of age. The database of the NSIDR in Ireland was interrogated and cases of SIDS and SUDC were compared over a fifteen-year period (1995-2009). SIDS cases whose autopsies were conducted in the same hospital in the same year as the index SUDC case were used for comparison. The autopsy report for each case was examined and modified Rushton(MR) scores 1\\r\
DEFF Research Database (Denmark)
Solomon, Scott D; Zelenkofske, Steve; McMurray, John J V
2005-01-01
BACKGROUND: The risk of sudden death from cardiac causes is increased among survivors of acute myocardial infarction with reduced left ventricular systolic function. We assessed the risk and time course of sudden death in high-risk patients after myocardial infarction. METHODS: We studied 14......,609 patients with left ventricular dysfunction, heart failure, or both after myocardial infarction to assess the incidence and timing of sudden unexpected death or cardiac arrest with resuscitation in relation to the left ventricular ejection fraction. RESULTS: Of 14,609 patients, 1067 (7 percent) had an event...... percent confidence interval, 0.11 to 0.18 percent) after 2 years. Patients with a left ventricular ejection fraction of 30 percent or less were at highest risk in this early period (rate, 2.3 percent per month; 95 percent confidence interval, 1.8 to 2.8 percent). Nineteen percent of all sudden deaths...
AN AUDIT OF THE SUDDEN-INFANT-DEATH-SYNDROME PREVENTION PROGRAM IN THE AUCKLAND REGION
Obdeijn, M. C.; Tonkin, S.; Mitchell, E. A.
1995-01-01
Aim. An audit of the sudden infant death syndrome (SIDS) prevention programme in the Auckland region. Methods. 107 health professionals working in antenatal classes, postnatal wards, domiciliary midwifery and the Plunket Society were interviewed. Results. Maternal smoking and infant sleeping
The initial phase of sudden releases of superheated liquid
International Nuclear Information System (INIS)
Schmidli, J.
1994-04-01
The catastrophic failure of a pressure vessel containing a liquefied substance, leading to an instantaneous release of its whole contents is considered as one of the major technological hazards. Due to the rapid depressurization caused by vessel failure, the fluid becomes superheated and unstable. Part of the fluid will evaporate using its internal energy and the two-phase mixture forming will be accelerated. This flashing process can be very violent, as experiments and incidents actually happened have shown. In the past, a number of dispersion models were developed to predict the history of an instantaneous release. In most of these models the source term is considered to be a gas volume at rest and not a rapidly expanding aerosol, as could be observed. Furthermore, it is usually assumed that all of the remaining fluid is entrained into the expanding cloud and nothing is deposited on the ground to form a pool. This work concentrates on the initial phase of the sudden release of superheated liquids with the aim to gain a better understanding of the flashing process and of the physical mechanisms involved, leading to a reliable prediction of the source term. Therefore, more than 400 experiments with propane, butane, refrigerant 12 and 114 were conducted. The experiments were initiated by shattering spherical glass flasks of different sizes. The main parameters varied were the liquid superheat and the filling level of the vessel. Using high-speed video and movie recordings and very fast responding measurement devices, it was possible to study the initial phase of such releases during which gravity plays no role. For sufficiently large released internal energy, the initial evolution of the release was always spherical with a constant radial expansion velocity during he first milliseconds until instabilities appeared at the surface of the droplet/vapor cloud that was formed. For all the experimental conditions, the fraction of the initial liquid falling on the ground
Cardiovascular Risk Factors in Primary Relatives of Sudden Cardiac Death Victims
1991-01-01
hypertriglyceridemia and hypertension as risk factors in relatives of sudden death victims. The sample for both studies will be the same. 5 Chapter II The...provided most of the research information on SCD. Pathology of Sudden Cardiac Death There appear to be several different pathologic scenarios which render a...had severe two or three vessel disease. By comparison, 100 age matched controls who died of other causes, had a combined 27% incidence of two and
F-MARC: promoting the prevention and management of sudden cardiac arrest in football
Kramer, Efraim Benjamin; Dvorak, J; Schmied, C; Meyer, T
2015-01-01
Sudden cardiac death is the most common cause of unnatural death in football. To prevent and urgently manage sudden cardiac arrest on the football field-of-play, F-MARC (FIFA Medical and Research Centre) has been fully committed to a programme of research, education, standardisation and practical implementation. This strategy has detected football players at medical risk during mandatory precompetition medical assessments. Additionally, FIFA has (1) sponsored internationally accepted guidelin...
Hidehiko Okamoto; Munehisa Fukushima; Henning Teismann; Lothar Lagemann; Tadashi Kitahara; Hidenori Inohara; Ryusuke Kakigi; Christo Pantev
2014-01-01
Sudden sensorineural hearing loss is characterized by acute, idiopathic hearing deterioration. We report here the development and evaluation of “constraint-induced sound therapy”, which is based on a well-established neuro-rehabilitation approach, and which is characterized by the plugging of the intact ear (“constraint”) and the simultaneous, extensive stimulation of the affected ear with music. The sudden sensorineural hearing loss patients who received the constraint-induced sound therapy ...
Epilepsy and risk of death and sudden unexpected death in the young
DEFF Research Database (Denmark)
Holst, Anders Gaarsdal; Winkel, Bo Gregers; Risgaard, Bjarke
2013-01-01
Patients with epilepsy are at increased risk of premature death from all causes and likely also from sudden unexplained death (SUD). Many patients with epilepsy have significant comorbidity, and it is unclear how much of the increased risk can be explained by epilepsy itself. We aimed to chart...... the incidence of sudden unexpected death in epilepsy (SUDEP) and estimate the risk of death from all causes and SUD conferred by epilepsy independently....
Characteristics of sudden bath-related death investigated by medical examiners in Tokyo, Japan.
Suzuki, Hideto; Hikiji, Wakako; Tanifuji, Takanobu; Abe, Nobuyuki; Fukunaga, Tatsushige
2015-01-01
Sudden bath-related deaths occur frequently in Japan, particularly among elderly people. However, the precise mechanism of bath-related death remains uncertain, and effective prevention strategies have not been established. Cases of bath-related deaths (n = 3289) were selected from all cases handled by the Tokyo Medical Examiner's Office from 2009 to 2011 (N = 41 336). The ages and occurrence dates were examined, and major autopsy findings, including toxicological analysis, were evaluated for the autopsied cases (n = 550). Most cases occurred in individuals older than 60 years of age during winter. Analysis of autopsy findings revealed water inhalation signs in many cases (n = 435, 79.1%). Circulatory system diseases constituted more than half of the pathological findings regarding factors that may have contributed significantly to death (n = 300, 54.5%), and cardiac lesions were the most common pathological finding (n = 250, 45.5%). However, approximately one-third of the cases exhibited no remarkable pathological findings (n = 198, 36.0%). A quarter of all cases involved blood ethanol levels that exceeded 0.5 mg/mL (n = 140). The results suggested that drowning plays an important role in the final process of bath-related death. Circulatory system diseases may be the primary underlying pathology; however, there were variations in the medical histories and pathologies of cases of bath-related death. From a preventive perspective, family members should pay attention to elderly people with circulatory system diseases during bathing, particularly in winter. Additionally, the notion that ill or inebriated individuals should not take baths should be reinforced.
Arousal responses in babies at risk of sudden infant death syndrome at different postnatal ages.
LENUS (Irish Health Repository)
Dunne, K P
1992-03-01
Hypercarbic and hypoxic arousal responses during sleep were measured in healthy term infants, infants where a previous sibling died from sudden infant death syndrome (SIDS) and infants suffering a clearly defined apparent life threatening event (ALTE) requiring vigorous or mouth to mouth resuscitation. Groups of infants were tested at approximately one, six and 13 weeks postnatally. Arousal was defined as gross body movement with eyes opening and moving or crying. Hypercarbic arousal was by step increases in F1 Co2 until arousal occurred or until endtidal (PETCO2) reached 8.7 KpA (65 mm Hg) Hypoxic arousal was by step decreases in FIO2 until arousal occurred or until an FIO2 of 0.15 had been maintained for 20 minutes. There was no difference in hypercaribic arousal threshold with age in any group. Hypercarbic arousal threshold was significantly higher in siblings (mean 53.4, 53.6, 54.7 mmHg. [7.12, 7.14, 7.29 KPA] at 0, 6, 13 postnatal weeks) compared to controls (mean 50.9, 52.3, 53.0mm Hg. [6.78, 6.97, 7.29 KPS respectively). ALTE infants differed only at 12 weeks having a significantly lower threshold (51.0mmHg. [6.80 KPA] V 53.0mm Hg. (7.06 KPA]) compared to controls. There was no difference in hypoxic arousal response with age in any group. An arousal response to hypoxia occurred in only 22% of ALTE infants and 40% of siblings compared to 67% of normal infants. Deficient sleep arousal, especially to hypoxia, is common in infants and especially those considered at increased risk from SIDS. This deficiency is present in the first postnatal week and did not vary overy the first three months of postnatal life.
Cosmological applications of Padé approximant
International Nuclear Information System (INIS)
Wei, Hao; Yan, Xiao-Peng; Zhou, Ya-Nan
2014-01-01
As is well known, in mathematics, any function could be approximated by the Padé approximant. The Padé approximant is the best approximation of a function by a rational function of given order. In fact, the Padé approximant often gives better approximation of the function than truncating its Taylor series, and it may still work where the Taylor series does not converge. In the present work, we consider the Padé approximant in two issues. First, we obtain the analytical approximation of the luminosity distance for the flat XCDM model, and find that the relative error is fairly small. Second, we propose several parameterizations for the equation-of-state parameter (EoS) of dark energy based on the Padé approximant. They are well motivated from the mathematical and physical points of view. We confront these EoS parameterizations with the latest observational data, and find that they can work well. In these practices, we show that the Padé approximant could be an useful tool in cosmology, and it deserves further investigation
Cosmological applications of Padé approximant
Wei, Hao; Yan, Xiao-Peng; Zhou, Ya-Nan
2014-01-01
As is well known, in mathematics, any function could be approximated by the Padé approximant. The Padé approximant is the best approximation of a function by a rational function of given order. In fact, the Padé approximant often gives better approximation of the function than truncating its Taylor series, and it may still work where the Taylor series does not converge. In the present work, we consider the Padé approximant in two issues. First, we obtain the analytical approximation of the luminosity distance for the flat XCDM model, and find that the relative error is fairly small. Second, we propose several parameterizations for the equation-of-state parameter (EoS) of dark energy based on the Padé approximant. They are well motivated from the mathematical and physical points of view. We confront these EoS parameterizations with the latest observational data, and find that they can work well. In these practices, we show that the Padé approximant could be an useful tool in cosmology, and it deserves further investigation.
An Experimental Study on Flow Boiling Critical Heat Flux Characteristics of Suddenly Expanded Region
Energy Technology Data Exchange (ETDEWEB)
Kim, Yong Jin; Song, Sub Lee; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Moon, Sang Ki [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-05-15
In this experiment, test section has been designed to simulate sudden flow path change due to deformation of cladding. It was tended to simulate cladding deformation that has discontinuous diameter change so coolant flow path changes suddenly. Experiments are in progress. Experiments on test section that simulate deformed flow path which contains sudden contraction and sudden expansion part have been done. Location of CHF has been varied by different condition of experiment. CHF at the outlet of test section fits well into the Macbeth's correlation and data of reference experiment, which was held on plain test section that had same diameter with inlet diameter of deformed test section. CHF at sudden expansion part was in churn flow regime and CHF was very low compared to expectation. It is discussed that liquid film separation from wall or bubble accumulation by backflow might be the reason of this result. For future work, experiments for two additional blockage ratio conditions will be carried out. Also, discussion and model development for deformed channel with sudden expand flow path will be held on.
F-MARC: promoting the prevention and management of sudden cardiac arrest in football.
Kramer, Efraim Benjamin; Dvorak, J; Schmied, C; Meyer, T
2015-05-01
Sudden cardiac death is the most common cause of unnatural death in football. To prevent and urgently manage sudden cardiac arrest on the football field-of-play, F-MARC (FIFA Medical and Research Centre) has been fully committed to a programme of research, education, standardisation and practical implementation. This strategy has detected football players at medical risk during mandatory precompetition medical assessments. Additionally, FIFA has (1) sponsored internationally accepted guidelines for the interpretation of an athlete's ECG, (2) developed field-of-play-specific protocols for the recognition, response, resuscitation and removal of a football player having sudden cardiac arrest and (3) introduced and distributed the FIFA medical emergency bag which has already resulted in the successful resuscitation of a football player who had a sudden cardiac arrest on the field-of-play. Recently FIFA, in association with the Institute of Sports and Preventive Medicine in Saarbrücken, Germany, established a worldwide Sudden Death Registry with a view to documenting fatal events on the football field-of-play. These activities by F-MARC are testimony to FIFA's continued commitment to minimising sudden cardiac arrest while playing football. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Relationship between sudden natural death and abdominal fat evaluated on postmortem CT scans.
Kaichi, Y; Sakane, H; Higashibori, H; Honda, Y; Tatsugami, F; Baba, Y; Iida, M; Awai, K
2017-06-01
This study examined the association between sudden natural death and abdominal fat using postmortem computed tomography (CT) scans. Postmortem CT images at the umbilical level of 241 subjects were used to measure abdominal areas of subcutaneous- and visceral fat, the rate of visceral fat and the waist circumference. Of the study subjects, 174 died of sudden natural death (130 men and 44 women), and 67 died of different causes (46 men and 21 women). All were between 40 and 75 years of age. Logistic regression analysis was performed to identify independent abdominal parameters associated with sudden natural death. By univariate analysis, the areas of subcutaneous and visceral fat were significantly larger in sudden natural death than who died of different causes (subcutaneous fat, odds ratio [OR] = 1.004, 95% confidence interval [CI] = 1.000-1.007, p = 0.03; visceral fat, OR = 1.008, 95% CI = 1.003-1.013, p fat was an independent factor associated with the risk of sudden natural death (OR = 1.008, 95% CI = 1.002-1.015, p = 0.02). Postmortem CT revealed that sudden natural death was related to abdominal fat deposits.
Multilevel Monte Carlo in Approximate Bayesian Computation
Jasra, Ajay
2017-02-13
In the following article we consider approximate Bayesian computation (ABC) inference. We introduce a method for numerically approximating ABC posteriors using the multilevel Monte Carlo (MLMC). A sequential Monte Carlo version of the approach is developed and it is shown under some assumptions that for a given level of mean square error, this method for ABC has a lower cost than i.i.d. sampling from the most accurate ABC approximation. Several numerical examples are given.
Uniform analytic approximation of Wigner rotation matrices
Hoffmann, Scott E.
2018-02-01
We derive the leading asymptotic approximation, for low angle θ, of the Wigner rotation matrix elements, dm1m2 j(θ ) , uniform in j, m1, and m2. The result is in terms of a Bessel function of integer order. We numerically investigate the error for a variety of cases and find that the approximation can be useful over a significant range of angles. This approximation has application in the partial wave analysis of wavepacket scattering.
Exact and approximate multiple diffraction calculations
International Nuclear Information System (INIS)
Alexander, Y.; Wallace, S.J.; Sparrow, D.A.
1976-08-01
A three-body potential scattering problem is solved in the fixed scatterer model exactly and approximately to test the validity of commonly used assumptions of multiple scattering calculations. The model problem involves two-body amplitudes that show diffraction-like differential scattering similar to high energy hadron-nucleon amplitudes. The exact fixed scatterer calculations are compared to Glauber approximation, eikonal-expansion results and a noneikonal approximation
Bent approximations to synchrotron radiation optics
International Nuclear Information System (INIS)
Heald, S.
1981-01-01
Ideal optical elements can be approximated by bending flats or cylinders. This paper considers the applications of these approximate optics to synchrotron radiation. Analytic and raytracing studies are used to compare their optical performance with the corresponding ideal elements. It is found that for many applications the performance is adequate, with the additional advantages of lower cost and greater flexibility. Particular emphasis is placed on obtaining the practical limitations on the use of the approximate elements in typical beamline configurations. Also considered are the possibilities for approximating very long length mirrors using segmented mirrors
Local density approximations for relativistic exchange energies
International Nuclear Information System (INIS)
MacDonald, A.H.
1986-01-01
The use of local density approximations to approximate exchange interactions in relativistic electron systems is reviewed. Particular attention is paid to the physical content of these exchange energies by discussing results for the uniform relativistic electron gas from a new point of view. Work on applying these local density approximations in atoms and solids is reviewed and it is concluded that good accuracy is usually possible provided self-interaction corrections are applied. The local density approximations necessary for spin-polarized relativistic systems are discussed and some new results are presented
Approximate maximum parsimony and ancestral maximum likelihood.
Alon, Noga; Chor, Benny; Pardi, Fabio; Rapoport, Anat
2010-01-01
We explore the maximum parsimony (MP) and ancestral maximum likelihood (AML) criteria in phylogenetic tree reconstruction. Both problems are NP-hard, so we seek approximate solutions. We formulate the two problems as Steiner tree problems under appropriate distances. The gist of our approach is the succinct characterization of Steiner trees for a small number of leaves for the two distances. This enables the use of known Steiner tree approximation algorithms. The approach leads to a 16/9 approximation ratio for AML and asymptotically to a 1.55 approximation ratio for MP.
APPROXIMATIONS TO PERFORMANCE MEASURES IN QUEUING SYSTEMS
Directory of Open Access Journals (Sweden)
Kambo, N. S.
2012-11-01
Full Text Available Approximations to various performance measures in queuing systems have received considerable attention because these measures have wide applicability. In this paper we propose two methods to approximate the queuing characteristics of a GI/M/1 system. The first method is non-parametric in nature, using only the first three moments of the arrival distribution. The second method treads the known path of approximating the arrival distribution by a mixture of two exponential distributions by matching the first three moments. Numerical examples and optimal analysis of performance measures of GI/M/1 queues are provided to illustrate the efficacy of the methods, and are compared with benchmark approximations.
Sudden distortion of turbulence at a forest edge
DEFF Research Database (Denmark)
Mann, Jakob; Dellwik, Ebba
2014-01-01
Dellwik et al. (2013) presented data from a forest edge experiment based on two meteorological towers instrumented with sonic anemometers. The experiment was performed at a dense edge of the Tromnæs Forest, which is a 24 m tall mature beech stand on the island Falster, Denmark. The topography...... in the lateral variance, whereas the streamwise variance remained approximately constant. This result is in contrast to the predictions by homogeneous rapid distortion theory. We apply and develop an alternative framework based on inhomogeneous rapid distortion theory, also called blocking, in combination...
Diagonal Pade approximations for initial value problems
International Nuclear Information System (INIS)
Reusch, M.F.; Ratzan, L.; Pomphrey, N.; Park, W.
1987-06-01
Diagonal Pade approximations to the time evolution operator for initial value problems are applied in a novel way to the numerical solution of these problems by explicitly factoring the polynomials of the approximation. A remarkable gain over conventional methods in efficiency and accuracy of solution is obtained. 20 refs., 3 figs., 1 tab
Approximation properties of fine hyperbolic graphs
Indian Academy of Sciences (India)
2016-08-26
Aug 26, 2016 ... In this paper, we propose a definition of approximation property which is called the metric invariant translation approximation property for a countable discrete metric space. Moreover, we use ... Department of Applied Mathematics, Shanghai Finance University, Shanghai 201209, People's Republic of China ...
Approximation properties of fine hyperbolic graphs
Indian Academy of Sciences (India)
2010 Mathematics Subject Classification. 46L07. 1. Introduction. Given a countable discrete group G, some nice approximation properties for the reduced. C∗-algebras C∗ r (G) can give us the approximation properties of G. For example, Lance. [7] proved that the nuclearity of C∗ r (G) is equivalent to the amenability of G; ...
Non-Linear Approximation of Bayesian Update
Litvinenko, Alexander
2016-01-01
We develop a non-linear approximation of expensive Bayesian formula. This non-linear approximation is applied directly to Polynomial Chaos Coefficients. In this way, we avoid Monte Carlo sampling and sampling error. We can show that the famous Kalman Update formula is a particular case of this update.
Simultaneous approximation in scales of Banach spaces
International Nuclear Information System (INIS)
Bramble, J.H.; Scott, R.
1978-01-01
The problem of verifying optimal approximation simultaneously in different norms in a Banach scale is reduced to verification of optimal approximation in the highest order norm. The basic tool used is the Banach space interpolation method developed by Lions and Peetre. Applications are given to several problems arising in the theory of finite element methods
Approximation algorithms for guarding holey polygons ...
African Journals Online (AJOL)
Guarding edges of polygons is a version of art gallery problem.The goal is finding the minimum number of guards to cover the edges of a polygon. This problem is NP-hard, and to our knowledge there are approximation algorithms just for simple polygons. In this paper we present two approximation algorithms for guarding ...
Efficient automata constructions and approximate automata
Watson, B.W.; Kourie, D.G.; Ngassam, E.K.; Strauss, T.; Cleophas, L.G.W.A.
2008-01-01
In this paper, we present data structures and algorithms for efficiently constructing approximate automata. An approximate automaton for a regular language L is one which accepts at least L. Such automata can be used in a variety of practical applications, including network security pattern
Efficient automata constructions and approximate automata
Watson, B.W.; Kourie, D.G.; Ngassam, E.K.; Strauss, T.; Cleophas, L.G.W.A.; Holub, J.; Zdárek, J.
2006-01-01
In this paper, we present data structures and algorithms for efficiently constructing approximate automata. An approximate automaton for a regular language L is one which accepts at least L. Such automata can be used in a variety of practical applications, including network security pattern
Spline approximation, Part 1: Basic methodology
Ezhov, Nikolaj; Neitzel, Frank; Petrovic, Svetozar
2018-04-01
In engineering geodesy point clouds derived from terrestrial laser scanning or from photogrammetric approaches are almost never used as final results. For further processing and analysis a curve or surface approximation with a continuous mathematical function is required. In this paper the approximation of 2D curves by means of splines is treated. Splines offer quite flexible and elegant solutions for interpolation or approximation of "irregularly" distributed data. Depending on the problem they can be expressed as a function or as a set of equations that depend on some parameter. Many different types of splines can be used for spline approximation and all of them have certain advantages and disadvantages depending on the approximation problem. In a series of three articles spline approximation is presented from a geodetic point of view. In this paper (Part 1) the basic methodology of spline approximation is demonstrated using splines constructed from ordinary polynomials and splines constructed from truncated polynomials. In the forthcoming Part 2 the notion of B-spline will be explained in a unique way, namely by using the concept of convex combinations. The numerical stability of all spline approximation approaches as well as the utilization of splines for deformation detection will be investigated on numerical examples in Part 3.
Nonlinear approximation with general wave packets
DEFF Research Database (Denmark)
Borup, Lasse; Nielsen, Morten
2005-01-01
We study nonlinear approximation in the Triebel-Lizorkin spaces with dictionaries formed by dilating and translating one single function g. A general Jackson inequality is derived for best m-term approximation with such dictionaries. In some special cases where g has a special structure, a complete...
Quirks of Stirling's Approximation
Macrae, Roderick M.; Allgeier, Benjamin M.
2013-01-01
Stirling's approximation to ln "n"! is typically introduced to physical chemistry students as a step in the derivation of the statistical expression for the entropy. However, naive application of this approximation leads to incorrect conclusions. In this article, the problem is first illustrated using a familiar "toy…
Non-Linear Approximation of Bayesian Update
Litvinenko, Alexander
2016-06-23
We develop a non-linear approximation of expensive Bayesian formula. This non-linear approximation is applied directly to Polynomial Chaos Coefficients. In this way, we avoid Monte Carlo sampling and sampling error. We can show that the famous Kalman Update formula is a particular case of this update.
Approximations for stop-loss reinsurance premiums
Reijnen, Rajko; Albers, Willem/Wim; Kallenberg, W.C.M.
2005-01-01
Various approximations of stop-loss reinsurance premiums are described in literature. For a wide variety of claim size distributions and retention levels, such approximations are compared in this paper to each other, as well as to a quantitative criterion. For the aggregate claims two models are
Improved Dutch Roll Approximation for Hypersonic Vehicle
Directory of Open Access Journals (Sweden)
Liang-Liang Yin
2014-06-01
Full Text Available An improved dutch roll approximation for hypersonic vehicle is presented. From the new approximations, the dutch roll frequency is shown to be a function of the stability axis yaw stability and the dutch roll damping is mainly effected by the roll damping ratio. In additional, an important parameter called roll-to-yaw ratio is obtained to describe the dutch roll mode. Solution shows that large-roll-to-yaw ratio is the generate character of hypersonic vehicle, which results the large error for the practical approximation. Predictions from the literal approximations derived in this paper are compared with actual numerical values for s example hypersonic vehicle, results show the approximations work well and the error is below 10 %.
Approximate error conjugation gradient minimization methods
Kallman, Jeffrey S
2013-05-21
In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.
Risk factors and causes of sudden noncardiac death: A nationwide cohort study in Denmark.
Risgaard, Bjarke; Lynge, Thomas Hadberg; Wissenberg, Mads; Jabbari, Reza; Glinge, Charlotte; Gislason, Gunnar Hilmar; Haunsø, Stig; Winkel, Bo Gregers; Tfelt-Hansen, Jacob
2015-05-01
On the performance of an autopsy, sudden deaths may be divided into 2 classifications: (1) sudden cardiac deaths and (2) sudden noncardiac deaths (SNCDs). Families of SNCD victims should not be followed up as a means of searching for cardiac disease. The purpose of this study was to report the risk factors and causes of SNCD. We conducted a retrospective, nationwide study including all deaths between 2000 and 2006 of individuals aged 1-35 years and all deaths between 2007 and 2009 of individuals aged 1-49 years. Two physicians identified all sudden death cases through review of death certificates. Autopsy reports were collected. A multivariable logistic regression model was used to identify both clinical characteristics and risk factors associated with SNCD. We identified 1039 autopsied cases of sudden death, of which 286 (28%) were classified as SNCD. The median age in the SNCD death population was 32 years. Increasing age was inversely associated with SNCD (odds ratio [OR] 0.93, 95% confidence interval [CI] 0.87-0.98). Female sex, in-hospital location, and the absence of cardiac comorbidities were positively associated with SNCD (OR 1.7, 95% CI 1.3-2.3; OR 3.0, 95% CI 2.0-4.4; and OR 4.3, 95% CI 2.5-7.4, respectively). The most common cause of SNCD was pulmonary disease (n = 115 [40%]). Sudden death among individuals aged caused by noncardiac diseases in 28% of cases. Risk factors were female sex, age, and the absence of cardiac comorbidities. These data may guide future strategies for the follow-up of family members of nonautopsied sudden death victims, improve risk stratification, and influence public health strategies. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
Systematic review of the incidence of sudden cardiac death in the United States.
Kong, Melissa H; Fonarow, Gregg C; Peterson, Eric D; Curtis, Anne B; Hernandez, Adrian F; Sanders, Gillian D; Thomas, Kevin L; Hayes, David L; Al-Khatib, Sana M
2011-02-15
The need for consistent and current data describing the true incidence of sudden cardiac arrest (SCA) and/or sudden cardiac death (SCD) was highlighted during the most recent Sudden Cardiac Arrest Thought Leadership Alliance's (SCATLA) Think Tank meeting of national experts with broad representation of key stakeholders, including thought leaders and representatives from the American College of Cardiology, American Heart Association, and the Heart Rhythm Society. As such, to evaluate the true magnitude of this public health problem, we performed a systematic literature search in MEDLINE using the MeSH headings, "death, sudden" OR the terms "sudden cardiac death" OR "sudden cardiac arrest" OR "cardiac arrest" OR "cardiac death" OR "sudden death" OR "arrhythmic death." Study selection criteria included peer-reviewed publications of primary data used to estimate SCD incidence in the U.S. We used Web of Science's Cited Reference Search to evaluate the impact of each primary estimate on the medical literature by determining the number of times each "primary source" has been cited. The estimated U.S. annual incidence of SCD varied widely from 180,000 to >450,000 among 6 included studies. These different estimates were in part due to different data sources (with data age ranging from 1980 to 2007), definitions of SCD, case ascertainment criteria, methods of estimation/extrapolation, and sources of case ascertainment. The true incidence of SCA and/or SCD in the U.S. remains unclear, with a wide range in the available estimates that are badly dated. As reliable estimates of SCD incidence are important for improving risk stratification and prevention, future efforts are clearly needed to establish uniform definitions of SCA and SCD and then to prospectively and precisely capture cases of SCA and SCD in the overall U.S. population. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Varvarigou, Vasileia; Farioli, Andrea; Korre, Maria; Sato, Sho; Dahabreh, Issa J; Kales, Stefanos N
2014-11-18
To assess the association between risk of sudden cardiac death and stressful law enforcement duties compared with routine/non-emergency duties. Case distribution study (case series with survey information on referent exposures). United States law enforcement. Summaries of deaths of over 4500 US police officers provided by the National Law Enforcement Officers Memorial Fund and the Officer Down Memorial Page from 1984 to 2010. Observed and expected sudden cardiac death counts and relative risks for sudden cardiac death events during specific strenuous duties versus routine/non-emergency activities. Independent estimates of the proportion of time that police officers spend across various law enforcement duties obtained from surveys of police chiefs and front line officers. Impact of varying exposure assessments, covariates, and missing cases in sensitivity and stability analyses. 441 sudden cardiac deaths were observed during the study period. Sudden cardiac death was associated with restraints/altercations (25%, n=108), physical training (20%, n=88), pursuits of suspects (12%, n=53), medical/rescue operations (8%, n=34), routine duties (23%, n=101), and other activities (11%, n=57). Compared with routine/non-emergency activities, the risk of sudden cardiac death was 34-69 times higher during restraints/altercations, 32-51 times higher during pursuits, 20-23 times higher during physical training, and 6-9 times higher during medical/rescue operations. Results were robust to all sensitivity and stability analyses. Stressful law enforcement duties are associated with a risk of sudden cardiac death that is markedly higher than the risk during routine/non-emergency duties. Restraints/altercations and pursuits are associated with the greatest risk. Our findings have public health implications and suggest that primary and secondary cardiovascular prevention efforts are needed among law enforcement officers. © Varvarigou et al 2014.
Approximate solutions: ramps and periodic variations. Chapter 5
International Nuclear Information System (INIS)
1998-01-01
The aim of reactor regulation is generally to maintain reactor power at the demand power, or to vary it slowly to attain a new demand power. On the other hand, the purpose of reactor shutdown systems (SDS) is to insert rapidly, on actuation, a large negative reactivity in order to minimize an overpower, or limit the energy released during a transient, so that fuel failure is improbable. Control mechanisms are therefore characterized by: their reactivity worth (mk), which must exceed the reactivity effect which the mechanism is designed to compensate; and their insertion rate (mk/s), which must be at least as fast as the effect to be controlled. Table 5.1 gives a summary of the various control mechanisms in a CANDU 6 reactor. The reactivity worth shown for each mechanism is the static reactivity change associated with full movement of the device. In reality, the dynamic reactivity will vary in a continuous manner, not suddenly, as assumed in the previous chapter. The realistic simulation of a reactivity insertion in the reactor must then take into account the rate of insertion of reactivity, which is governed by the insertion speed of the mechanism. We have seen in the previous chapter that it is possible to solved analytically the point-kinetics equations for constant reactivity. We could generalize these solutions to step-wise reactivity variations by linking together the analytic solutions to for a sequence of step changes. This approach is not necessarily the best from a numerical point of view. By introducing one or more simplifying assumptions, it will be possible to obtain an analytical solution of arbitrary variations in reactivity or in the external source. These assumptions will undoubtedly limit the applicability of the results, but the approximate solutions obtained will allow us to describe the reactor behaviour analytically. (author)
Sudden cardiac death in athletes and its preventive strategies: review article
Directory of Open Access Journals (Sweden)
Farzin Halabchi
2017-12-01
Full Text Available Sudden cardiac death in sport, although rare, but is a tragic event, attracting the media and public attention. Sport and exercise may act as a trigger for sudden cardiac death. Risk of sudden death in young athletes with cardiovascular disease is 2.5 times more frequent than non-athlete individuals. More than 90% of cases of sudden death occur during or immediately after training or competition. Incidence of sudden cardiac death in any population, including athletes, is related to multiple factors such as gender, age, race, nationality, diagnostic screening methods and preventive measures for sudden cardiac death. Otherwise, incidence rate of sudden cardiac death is linked to the used definition and method of diagnosis. Different cardiovascular disorders may result in death of young athletes and hypertrophic cardiomyopathy, congenital coronary anomalies, arrhythmogenic right ventricular dysplasia and aortic rupture are among the most common causes. Marfan syndrome, dilated cardiomyopathy, viral myocarditis, Wolff-Parkinson-White (WPW syndrome, congenital long QT syndrome, Brugada syndrome and commotio cordis are reported as other etiologies. In older athletes (more than 35 years, ischemic coronary heart disease is responsible for majority of the cases similar to the general population. Because the outcome of sudden cardiac arrest in sports is very poor except in few cases, proper national strategies are needed to diminish the burden of sudden death in young athletes. It seems that there are two main strategies to achieve this goal: A Primary prevention with use of purposeful pre-participation evaluation programs. This evaluation should focuss on the proper history and physical examination. Nevertheless, there is significant debate between American and European countries regarding the use of paraclinical investigations (especially ECG. American heart association does not recommend ECG as an essential part of evaluation. In contrast, European
Regression with Sparse Approximations of Data
DEFF Research Database (Denmark)
Noorzad, Pardis; Sturm, Bob L.
2012-01-01
We propose sparse approximation weighted regression (SPARROW), a method for local estimation of the regression function that uses sparse approximation with a dictionary of measurements. SPARROW estimates the regression function at a point with a linear combination of a few regressands selected...... by a sparse approximation of the point in terms of the regressors. We show SPARROW can be considered a variant of \\(k\\)-nearest neighbors regression (\\(k\\)-NNR), and more generally, local polynomial kernel regression. Unlike \\(k\\)-NNR, however, SPARROW can adapt the number of regressors to use based...
Conditional Density Approximations with Mixtures of Polynomials
DEFF Research Database (Denmark)
Varando, Gherardo; López-Cruz, Pedro L.; Nielsen, Thomas Dyhre
2015-01-01
Mixtures of polynomials (MoPs) are a non-parametric density estimation technique especially designed for hybrid Bayesian networks with continuous and discrete variables. Algorithms to learn one- and multi-dimensional (marginal) MoPs from data have recently been proposed. In this paper we introduce...... two methods for learning MoP approximations of conditional densities from data. Both approaches are based on learning MoP approximations of the joint density and the marginal density of the conditioning variables, but they differ as to how the MoP approximation of the quotient of the two densities...
Hardness and Approximation for Network Flow Interdiction
Chestnut, Stephen R.; Zenklusen, Rico
2015-01-01
In the Network Flow Interdiction problem an adversary attacks a network in order to minimize the maximum s-t-flow. Very little is known about the approximatibility of this problem despite decades of interest in it. We present the first approximation hardness, showing that Network Flow Interdiction and several of its variants cannot be much easier to approximate than Densest k-Subgraph. In particular, any $n^{o(1)}$-approximation algorithm for Network Flow Interdiction would imply an $n^{o(1)}...
Approximation of the semi-infinite interval
Directory of Open Access Journals (Sweden)
A. McD. Mercer
1980-01-01
Full Text Available The approximation of a function f∈C[a,b] by Bernstein polynomials is well-known. It is based on the binomial distribution. O. Szasz has shown that there are analogous approximations on the interval [0,∞ based on the Poisson distribution. Recently R. Mohapatra has generalized Szasz' result to the case in which the approximating function is αe−ux∑k=N∞(uxkα+β−1Γ(kα+βf(kαuThe present note shows that these results are special cases of a Tauberian theorem for certain infinite series having positive coefficients.
Mathematical analysis, approximation theory and their applications
Gupta, Vijay
2016-01-01
Designed for graduate students, researchers, and engineers in mathematics, optimization, and economics, this self-contained volume presents theory, methods, and applications in mathematical analysis and approximation theory. Specific topics include: approximation of functions by linear positive operators with applications to computer aided geometric design, numerical analysis, optimization theory, and solutions of differential equations. Recent and significant developments in approximation theory, special functions and q-calculus along with their applications to mathematics, engineering, and social sciences are discussed and analyzed. Each chapter enriches the understanding of current research problems and theories in pure and applied research.
Directory of Open Access Journals (Sweden)
Nora Fnon
2016-06-01
Full Text Available This study aimed at evaluating the epidemiological characteristics and pathological features of different types of cardiomyopathies in Egypt, highlighting the role of the forensic pathologist in identifying cases of cardiomyopathies and initiating for their families a possible genetic study aiming at prevention of sudden death. All cases with sudden cardiac death (SCD due to cardiomyopathies during the period from the beginning of January 2010 until the end of December 2014 (5 years were included in this study. All hearts underwent detailed gross and histological examination. Circumstances of death, medical history, and post-mortem pathological findings were thoroughly investigated. Out of 535 cases of sudden cardiac death, there were 22 cases (4.1% diagnosed as having cardiomyopathies; sudden death was their first presentation. Eighteen cases (81.8% were male, with the 4th decade (11 cases, 50% being the most affected age; severe physical activity and exertion were evident in death circumstances of 14 cases (63.6%; pathological evaluation revealed that hypertrophic cardiomyopathy was the most frequent type, being diagnosed in 10 cases (45%. Cardiomyopathies are an infrequent cause of sudden cardiac death. Most deaths are in children and adults, so cases are of high social impact that demands multidisciplinary research and resources. In all cases of SCD, forensic autopsy should be done. Forensic study is the key to identifying an affected family and the starting point regarding assessing them.
Directory of Open Access Journals (Sweden)
John Bilbily
2017-01-01
Full Text Available A literature search identified 9 previously published cases that were considered as possible cases of catatonia secondary to sudden clozapine withdrawal. Two of these 9 cases did not provide enough information to make a diagnosis of catatonia according to the Diagnostic and Statistical Manual, 5th Edition (DSM-5. The Liverpool Adverse Drug Reaction (ADR Causality Scale was modified to assess ADRs secondary to drug withdrawal. From the 7 published cases which met DSM-5 catatonia criteria, using the modified scale, we established that 3 were definitive and 4 were probable cases of catatonia secondary to clozapine withdrawal. A new definitive case is described with three catatonic episodes which (1 occurred after sudden discontinuation of clozapine in the context of decades of follow-up, (2 had ≥3 of 12 DSM-5 catatonic symptoms and serum creatinine kinase elevation, and (3 required medical hospitalization and intravenous fluids. Clozapine may be a gamma-aminobutyric acid (GABA receptor agonist; sudden clozapine withdrawal may explain a sudden decrease in GABA activity that may contribute to the development of catatonic symptoms in vulnerable patients. Based on the limited information from these cases, the pharmacological treatment for catatonia secondary to sudden clozapine withdrawal can include benzodiazepines and/or restarting clozapine.
Is there an association between depression and cardiovascular mortality or sudden death?
Alboni, Paolo; Favaron, Elisa; Paparella, Nelly; Sciammarella, Massimo; Pedaci, Mario
2008-04-01
The results of many studies and recent meta-analyses strongly suggest that depression is a risk factor for total and cardiovascular mortality, both in the general population and in patients with known heart disease. By contrast, the association between depression and sudden death or cardiac arrest has received little attention. This issue has been investigated in three recent studies; two were carried out in the general population and showed depression to be a independent risk factor for sudden death. The other study was carried out in patients with acute myocardial infarction (AMI); the adjusted relative risk (RR) of sudden death was significantly increased in depressed patients but, after adjustment for dyspnea/fatigue (a common symptom for heart disease and depression), the RR was no longer statistically significant. However, when the cognitive-affective depressive symptoms were examined separately from the somatic ones (dyspnea/fatigue, etc.), there was a clear trend for an association between cognitive-affective symptoms and sudden death. Because a risk factor can be defined as 'independent' only in a multivariate analysis in which variables are dichotomized, the presence of common symptoms between heart disease and depression represents a very difficult problem. However, taken together, the results of studies carried out in the general population and in patients with AMI strongly suggest that depression is a significant risk factor for sudden death.
Multilevel weighted least squares polynomial approximation
Haji-Ali, Abdul-Lateef; Nobile, Fabio; Tempone, Raul; Wolfers, Sö ren
2017-01-01
, obtaining polynomial approximations with a single level method can become prohibitively expensive, as it requires a sufficiently large number of samples, each computed with a sufficiently small discretization error. As a solution to this problem, we propose
Low Rank Approximation Algorithms, Implementation, Applications
Markovsky, Ivan
2012-01-01
Matrix low-rank approximation is intimately related to data modelling; a problem that arises frequently in many different fields. Low Rank Approximation: Algorithms, Implementation, Applications is a comprehensive exposition of the theory, algorithms, and applications of structured low-rank approximation. Local optimization methods and effective suboptimal convex relaxations for Toeplitz, Hankel, and Sylvester structured problems are presented. A major part of the text is devoted to application of the theory. Applications described include: system and control theory: approximate realization, model reduction, output error, and errors-in-variables identification; signal processing: harmonic retrieval, sum-of-damped exponentials, finite impulse response modeling, and array processing; machine learning: multidimensional scaling and recommender system; computer vision: algebraic curve fitting and fundamental matrix estimation; bioinformatics for microarray data analysis; chemometrics for multivariate calibration; ...
Nonlinear Ritz approximation for Fredholm functionals
Directory of Open Access Journals (Sweden)
Mudhir A. Abdul Hussain
2015-11-01
Full Text Available In this article we use the modify Lyapunov-Schmidt reduction to find nonlinear Ritz approximation for a Fredholm functional. This functional corresponds to a nonlinear Fredholm operator defined by a nonlinear fourth-order differential equation.
Euclidean shortest paths exact or approximate algorithms
Li, Fajie
2014-01-01
This book reviews algorithms for the exact or approximate solution of shortest-path problems, with a specific focus on a class of algorithms called rubberband algorithms. The coverage includes mathematical proofs for many of the given statements.
Square well approximation to the optical potential
International Nuclear Information System (INIS)
Jain, A.K.; Gupta, M.C.; Marwadi, P.R.
1976-01-01
Approximations for obtaining T-matrix elements for a sum of several potentials in terms of T-matrices for individual potentials are studied. Based on model calculations for S-wave for a sum of two separable non-local potentials of Yukawa type form factors and a sum of two delta function potentials, it is shown that the T-matrix for a sum of several potentials can be approximated satisfactorily over all the energy regions by the sum of T-matrices for individual potentials. Based on this, an approximate method for finding T-matrix for any local potential by approximating it by a sum of suitable number of square wells is presented. This provides an interesting way to calculate the T-matrix for any arbitary potential in terms of Bessel functions to a good degree of accuracy. The method is applied to the Saxon-Wood potentials and good agreement with exact results is found. (author)
Approximation for the adjoint neutron spectrum
International Nuclear Information System (INIS)
Suster, Luis Carlos; Martinez, Aquilino Senra; Silva, Fernando Carvalho da
2002-01-01
The proposal of this work is the determination of an analytical approximation which is capable to reproduce the adjoint neutron flux for the energy range of the narrow resonances (NR). In a previous work we developed a method for the calculation of the adjoint spectrum which was calculated from the adjoint neutron balance equations, that were obtained by the collision probabilities method, this method involved a considerable quantity of numerical calculation. In the analytical method some approximations were done, like the multiplication of the escape probability in the fuel by the adjoint flux in the moderator, and after these approximations, taking into account the case of the narrow resonances, were substituted in the adjoint neutron balance equation for the fuel, resulting in an analytical approximation for the adjoint flux. The results obtained in this work were compared to the results generated with the reference method, which demonstrated a good and precise results for the adjoint neutron flux for the narrow resonances. (author)
Saddlepoint approximation methods in financial engineering
Kwok, Yue Kuen
2018-01-01
This book summarizes recent advances in applying saddlepoint approximation methods to financial engineering. It addresses pricing exotic financial derivatives and calculating risk contributions to Value-at-Risk and Expected Shortfall in credit portfolios under various default correlation models. These standard problems involve the computation of tail probabilities and tail expectations of the corresponding underlying state variables. The text offers in a single source most of the saddlepoint approximation results in financial engineering, with different sets of ready-to-use approximation formulas. Much of this material may otherwise only be found in original research publications. The exposition and style are made rigorous by providing formal proofs of most of the results. Starting with a presentation of the derivation of a variety of saddlepoint approximation formulas in different contexts, this book will help new researchers to learn the fine technicalities of the topic. It will also be valuable to quanti...
Methods of Fourier analysis and approximation theory
Tikhonov, Sergey
2016-01-01
Different facets of interplay between harmonic analysis and approximation theory are covered in this volume. The topics included are Fourier analysis, function spaces, optimization theory, partial differential equations, and their links to modern developments in the approximation theory. The articles of this collection were originated from two events. The first event took place during the 9th ISAAC Congress in Krakow, Poland, 5th-9th August 2013, at the section “Approximation Theory and Fourier Analysis”. The second event was the conference on Fourier Analysis and Approximation Theory in the Centre de Recerca Matemàtica (CRM), Barcelona, during 4th-8th November 2013, organized by the editors of this volume. All articles selected to be part of this collection were carefully reviewed.
Pion-nucleus cross sections approximation
International Nuclear Information System (INIS)
Barashenkov, V.S.; Polanski, A.; Sosnin, A.N.
1990-01-01
Analytical approximation of pion-nucleus elastic and inelastic interaction cross-section is suggested, with could be applied in the energy range exceeding several dozens of MeV for nuclei heavier than beryllium. 3 refs.; 4 tabs
APPROXIMATE DEVELOPMENTS FOR SURFACES OF REVOLUTION
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Mădălina Roxana Buneci
2016-12-01
Full Text Available The purpose of this paper is provide a set of Maple procedures to construct approximate developments of a general surface of revolution generalizing the well-known gore method for sphere
Steepest descent approximations for accretive operator equations
International Nuclear Information System (INIS)
Chidume, C.E.
1993-03-01
A necessary and sufficient condition is established for the strong convergence of the steepest descent approximation to a solution of equations involving quasi-accretive operators defined on a uniformly smooth Banach space. (author). 49 refs
Seismic wave extrapolation using lowrank symbol approximation
Fomel, Sergey
2012-04-30
We consider the problem of constructing a wave extrapolation operator in a variable and possibly anisotropic medium. Our construction involves Fourier transforms in space combined with the help of a lowrank approximation of the space-wavenumber wave-propagator matrix. A lowrank approximation implies selecting a small set of representative spatial locations and a small set of representative wavenumbers. We present a mathematical derivation of this method, a description of the lowrank approximation algorithm and numerical examples that confirm the validity of the proposed approach. Wave extrapolation using lowrank approximation can be applied to seismic imaging by reverse-time migration in 3D heterogeneous isotropic or anisotropic media. © 2012 European Association of Geoscientists & Engineers.
An overview on Approximate Bayesian computation*
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Baragatti Meïli
2014-01-01
Full Text Available Approximate Bayesian computation techniques, also called likelihood-free methods, are one of the most satisfactory approach to intractable likelihood problems. This overview presents recent results since its introduction about ten years ago in population genetics.
Approximate Computing Techniques for Iterative Graph Algorithms
Energy Technology Data Exchange (ETDEWEB)
Panyala, Ajay R.; Subasi, Omer; Halappanavar, Mahantesh; Kalyanaraman, Anantharaman; Chavarria Miranda, Daniel G.; Krishnamoorthy, Sriram
2017-12-18
Approximate computing enables processing of large-scale graphs by trading off quality for performance. Approximate computing techniques have become critical not only due to the emergence of parallel architectures but also the availability of large scale datasets enabling data-driven discovery. Using two prototypical graph algorithms, PageRank and community detection, we present several approximate computing heuristics to scale the performance with minimal loss of accuracy. We present several heuristics including loop perforation, data caching, incomplete graph coloring and synchronization, and evaluate their efficiency. We demonstrate performance improvements of up to 83% for PageRank and up to 450x for community detection, with low impact of accuracy for both the algorithms. We expect the proposed approximate techniques will enable scalable graph analytics on data of importance to several applications in science and their subsequent adoption to scale similar graph algorithms.
Approximative solutions of stochastic optimization problem
Czech Academy of Sciences Publication Activity Database
Lachout, Petr
2010-01-01
Roč. 46, č. 3 (2010), s. 513-523 ISSN 0023-5954 R&D Projects: GA ČR GA201/08/0539 Institutional research plan: CEZ:AV0Z10750506 Keywords : Stochastic optimization problem * sensitivity * approximative solution Subject RIV: BA - General Mathematics Impact factor: 0.461, year: 2010 http://library.utia.cas.cz/separaty/2010/SI/lachout-approximative solutions of stochastic optimization problem.pdf
Lattice quantum chromodynamics with approximately chiral fermions
Energy Technology Data Exchange (ETDEWEB)
Hierl, Dieter
2008-05-15
In this work we present Lattice QCD results obtained by approximately chiral fermions. We use the CI fermions in the quenched approximation to investigate the excited baryon spectrum and to search for the {theta}{sup +} pentaquark on the lattice. Furthermore we developed an algorithm for dynamical simulations using the FP action. Using FP fermions we calculate some LECs of chiral perturbation theory applying the epsilon expansion. (orig.)
An approximate analytical approach to resampling averages
DEFF Research Database (Denmark)
Malzahn, Dorthe; Opper, M.
2004-01-01
Using a novel reformulation, we develop a framework to compute approximate resampling data averages analytically. The method avoids multiple retraining of statistical models on the samples. Our approach uses a combination of the replica "trick" of statistical physics and the TAP approach for appr...... for approximate Bayesian inference. We demonstrate our approach on regression with Gaussian processes. A comparison with averages obtained by Monte-Carlo sampling shows that our method achieves good accuracy....
Stochastic quantization and mean field approximation
International Nuclear Information System (INIS)
Jengo, R.; Parga, N.
1983-09-01
In the context of the stochastic quantization we propose factorized approximate solutions for the Fokker-Planck equation for the XY and Zsub(N) spin systems in D dimensions. The resulting differential equation for a factor can be solved and it is found to give in the limit of t→infinity the mean field or, in the more general case, the Bethe-Peierls approximation. (author)
Polynomial approximation of functions in Sobolev spaces
International Nuclear Information System (INIS)
Dupont, T.; Scott, R.
1980-01-01
Constructive proofs and several generalizations of approximation results of J. H. Bramble and S. R. Hilbert are presented. Using an averaged Taylor series, we represent a function as a polynomical plus a remainder. The remainder can be manipulated in many ways to give different types of bounds. Approximation of functions in fractional order Sobolev spaces is treated as well as the usual integer order spaces and several nonstandard Sobolev-like spaces
Lattice quantum chromodynamics with approximately chiral fermions
International Nuclear Information System (INIS)
Hierl, Dieter
2008-05-01
In this work we present Lattice QCD results obtained by approximately chiral fermions. We use the CI fermions in the quenched approximation to investigate the excited baryon spectrum and to search for the Θ + pentaquark on the lattice. Furthermore we developed an algorithm for dynamical simulations using the FP action. Using FP fermions we calculate some LECs of chiral perturbation theory applying the epsilon expansion. (orig.)
Approximating centrality in evolving graphs: toward sublinearity
Priest, Benjamin W.; Cybenko, George
2017-05-01
The identification of important nodes is a ubiquitous problem in the analysis of social networks. Centrality indices (such as degree centrality, closeness centrality, betweenness centrality, PageRank, and others) are used across many domains to accomplish this task. However, the computation of such indices is expensive on large graphs. Moreover, evolving graphs are becoming increasingly important in many applications. It is therefore desirable to develop on-line algorithms that can approximate centrality measures using memory sublinear in the size of the graph. We discuss the challenges facing the semi-streaming computation of many centrality indices. In particular, we apply recent advances in the streaming and sketching literature to provide a preliminary streaming approximation algorithm for degree centrality utilizing CountSketch and a multi-pass semi-streaming approximation algorithm for closeness centrality leveraging a spanner obtained through iteratively sketching the vertex-edge adjacency matrix. We also discuss possible ways forward for approximating betweenness centrality, as well as spectral measures of centrality. We provide a preliminary result using sketched low-rank approximations to approximate the output of the HITS algorithm.
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Yumurtaci A.
2012-11-01
Full Text Available Salinity is one the major limiting environmental factors which has negative side effects on crop production. The purpose of this study was to investigate the differences between the gradual and sudden salt stress effects on biomass accumulation associated with whole plant development in three different tissues of two wheat species ( Triticum aestivum and Triticum durum under hydroponic conditions in the long term. Considering the effects of sudden and gradual stress for biomass accumulation, while importance of salinity x genotype interaction for fresh weights was 5%, association for salinity x tissue type was found as 1% important. Interestingly, root branching and development of lateral roots were much more negatively affected by gradual stress rather than sudden salt application. Our results demonstrated that root and leaf were both critical tissues to test the salt tolerance by physiologically but sheath tissue might be used as an alternative source of variation for solving the interactions between root and leaves in wheat.
Numerical simulation of the transport phenomena due to sudden heating in porous media
Energy Technology Data Exchange (ETDEWEB)
Lei, S.Y.; Zheng, G.Y.; Wang, B.X.; Yang, R.G.; Xia, C.M.
1997-07-01
Such process as wet porous media suddenly heated by hot fluids frequently occurs in nature and in industrial applications. The three-variable simulation model was developed to predict violent transport phenomena due to sudden heating in porous media. Two sets of independent variables were applied to different regions in porous media in the simulation. For the wet zone, temperature, wet saturation and air pressure were used as the independent variables. For the dry zone, the independent variables were temperature, vapor pressure and air pressure. The model simulated two complicated transport processes in wet unsaturated porous media which is suddenly heated by melting metal or boiling water. The effect of the gas pressure is also investigated on the overall transport phenomena.
Myerburg, Robert J; Ullmann, Steven G
2015-04-01
Although identification and management of cardiovascular risk markers have provided important population risk insights and public health benefits, individual risk prediction remains challenging. Using sudden cardiac death risk as a base case, the complex epidemiology of sudden cardiac death risk and the substantial new funding required to study individual risk are explored. Complex epidemiology derives from the multiple subgroups having different denominators and risk profiles, while funding limitations emerge from saturation of conventional sources of research funding without foreseeable opportunities for increases. A resolution to this problem would have to emerge from new sources of funding targeted to individual risk prediction. In this analysis, we explore the possibility of a research funding strategy that would offer business incentives to the insurance industries, while providing support for unresolved research goals. The model is developed for the case of sudden cardiac death risk, but the concept is applicable to other areas of the medical enterprise. © 2015 American Heart Association, Inc.
Sudden Cardiac Arrest due to Brugada Syndrome: a Case Report and Literature Review
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R Soleimanirad
2013-04-01
Full Text Available Brugada Syndrome is a rare cause of sudden cardiac arrest and has a unique ECG pattern. In fact, with ST-segment elevation down sloping in the right precordial leads (v1-v3, RBBB pattern in lateral leads and J-point elevation is revealed. We must notice and avoid trigger factors of this syndrome during general anesthesia. Patient is a 39 old man who attended to emergency department with sudden cardiac arrest and resuscitate. He was transferred to ICU for management of hypoxic ischemic encephalopathy. Complementary studies concluded the diagnosis of Brugada syndrome. We must consider Brugada syndrome within patients with family history of sudden cardiac arrest. Moreover, we must avoid trigger factors of this syndrome such as fever, bradicardia and electrolyte abnormality (specialy Na, Ca abnormalities during general anesthesia and if they appear, we should treat them.
How far is it to a sudden future singularity of pressure?
International Nuclear Information System (INIS)
DaPbrowski, Mariusz P.; Denkiewicz, Tomasz; Hendry, Martin A.
2007-01-01
We discuss the constraints coming from current observations of type Ia supernovae on cosmological models which allow sudden future singularities of pressure (with the scale factor and the energy density regular). We show that such a sudden singularity may happen in the very near future (e.g. within 10x10 6 years) and its prediction at the present moment of cosmic evolution cannot be distinguished, with current observational data, from the prediction given by the standard quintessence scenario of future evolution. Fortunately, sudden future singularities are characterized by a momentary peak of infinite tidal forces only; there is no geodesic incompleteness, which means that the evolution of the universe may eventually be continued throughout until another 'more serious' singularity such as a big crunch or big rip
Anti-HERG activity and the risk of drug-induced arrhythmias and sudden death
DEFF Research Database (Denmark)
De Bruin, M L; Pettersson, M; Meyboom, R H B
2005-01-01
AIMS: Drug-induced QTc-prolongation, resulting from inhibition of HERG potassium channels may lead to serious ventricular arrhythmias and sudden death. We studied the quantitative anti-HERG activity of pro-arrhythmic drugs as a risk factor for this outcome in day-to-day practice. METHODS...... defined as reports of cardiac arrest, sudden death, torsade de pointes, ventricular fibrillation, and ventricular tachycardia (n = 5591), and compared with non-cases regarding the anti-HERG activity, defined as the effective therapeutic plasma concentration (ETCPunbound) divided by the HERG IC50 value......, of suspected drugs. We identified a significant association of 1.93 (95% CI: 1.89-1.98) between the anti-HERG activity of drugs, measured as log10 (ETCPunbound/IC50), and reporting of serious ventricular arrhythmias and sudden death to the WHO-UMC database. CONCLUSION: Anti-HERG activity is associated...
Nationwide study of sudden cardiac death in persons aged 1-35 years
DEFF Research Database (Denmark)
Winkel, Bo Gregers; Holst, Anders Gaarsdal; Theilade, Juliane
2011-01-01
Aims The aim of this investigation was to study the incidence of sudden cardiac death (SCD) in persons aged 1-35 years in a nationwide setting (5.38 million people) by systematic evaluation of all deaths. Methods and results All deaths in persons aged 1-35 years in Denmark in 2000-06 were included....... Death certificates were read independently by two physicians. The National Patient Registry was used to retrieve information on prior medical history. All autopsy reports were read and the cause of death was revised based on autopsy findings. We identified 625 cases of sudden unexpected death (10......% of all deaths), of which 156 (25%) were not autopsied. Of the 469 autopsied cases, 314 (67%) were SCD. The most common cardiac cause of death was ischaemic heart disease (13%); 29% of autopsied sudden unexpected death cases were unexplained. In 45% of SCD cases, the death was witnessed; 34% died during...
Screening and risk evaluation for sudden cardiac death in ischaemic and non-ischaemic cardiomyopathy
DEFF Research Database (Denmark)
Proclemer, Alessandro; Lewalter, Thorsten; Bongiorni, Maria Grazia
2013-01-01
The purpose of this EHRA survey was to examine the current clinical practice of screening and risk evaluation for sudden cardiac death in ischaemic and non-ischaemic cardiomyopathy with a focus on selection of candidates for implantable cardioverter-defibrillator (ICD) therapy, timing of ICD...... implantation, and use of non-invasive and invasive diagnostic tests across Europe. A systematic screening programme for sudden cardiac death existed in 19 out of 31 centres (61.3%). Implantation of ICDs according to the inclusion criteria of MADIT-II and SCD-HeFT trials was reported in 30 and 29% of centres......, respectively, followed by MADIT-CRT (18%), COMPANION (16%), and combined MADIT and MUSTT (7%) indications. In patients with severe renal impairment, ICD implantation for primary prevention of sudden death was always avoided in 8 centres (33.3%), was not used only if creatinine level was >2.5 mg/dL in 10...
Ní Chróinín, Danielle; Lambert, John
2013-11-01
A 75-year-old lady presented with sudden severe headache and vomiting. Examination was normal, and CT and lumbar puncture not convincing for subarachnoid haemorrhage. Shortly thereafter, she developed painless diplopia. Examination confirmed right third cranial nerve palsy plus homonymous left inferior quadrantanopia. Urgent cerebral MRI with angiography was requested to assess for a possible posterior communicating artery aneurysm, but revealed an unsuspected pituitary mass. Pituitary adenoma with pituitary apoplexy was diagnosed. Pituitary apopolexy is a syndrome comprising sudden headache, meningism, visual and/or oculomotor deficits, with an intrasellar mass. It is commonly due to haemorrhage or infarction within a pituitary adenoma. Treatment includes prompt steroid administration, and potentially surgical decompression. While subarachnoid haemorrhage is an important, well-recognised cause of sudden severe headache, other aetiologies, including pituitary apoplexy, should be considered and sought.
Left Ventricular Aneurysm: Sudden Unexpected Deaths in a 29-Year-Old Man.
Srettabunjong, Supawon
2018-05-01
Left ventricular aneurysm (LVA) is an abnormal dilated heart structure, either congenital or acquired. LVA is a rare cardiac condition with no symptoms in most cases, thus occasionally diagnosed during investigations of other diseases. Its association with certain cardiac complications and sudden cardiac deaths has been reported. However, its role as a cause of sudden unexpected death is rare. The author reported a sudden cardiac death in a 29-year-old man with LVA. Without a significant coronary artery disease and known etiologies of LVA, such an abnormal heart structure in the present case was considered congenital LVA. As no other possible mechanisms of death could be identified other than LVA with its associated pathologic lesions, mural thrombi, and dilated cardiomegaly, his death was attributable to fatal cardiac arrhythmia (most commonly ventricular tachycardia) secondary to LVA. © 2017 American Academy of Forensic Sciences.
Stratification of the Risk of Sudden Death in Nonischemic Heart Failure
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Maurício Pimentel
2014-10-01
Full Text Available Despite significant therapeutic advancements, heart failure remains a highly prevalent clinical condition associated with significant morbidity and mortality. In 30%-40% patients, the etiology of heart failure is nonischemic. The implantable cardioverter-defibrillator (ICD is capable of preventing sudden death and decreasing total mortality in patients with nonischemic heart failure. However, a significant number of patients receiving ICD do not receive any kind of therapy during follow-up. Moreover, considering the situation in Brazil and several other countries, ICD cannot be implanted in all patients with nonischemic heart failure. Therefore, there is an urgent need to identify patients at an increased risk of sudden death because these would benefit more than patients at a lower risk, despite the presence of heart failure in both risk groups. In this study, the authors review the primary available methods for the stratification of the risk of sudden death in patients with nonischemic heart failure.
Directory of Open Access Journals (Sweden)
Matturri Luigi
2010-07-01
Full Text Available Abstract Background The ependyma, the lining providing a protective barrier and filtration system separating brain parenchyma from cerebrospinal fluid, is still inadequately understood in humans. In this study we aimed to define, by morphological and immunohistochemical methods, the sequence of developmental steps of the human ependyma in the brainstem (ventricular ependyma and thoracic spinal cord (central canal ependyma of a large sample of fetal and infant death victims, aged from 17 gestational weeks to 8 postnatal months. Additionally, we investigated a possible link between alterations of this structure, sudden unexplained fetal and infant death and maternal smoking. Results Our results demonstrate that in early fetal life the human ependyma shows a pseudostratified cytoarchitecture including many tanycytes and ciliated cells together with numerous apoptotic and reactive astrocytes in the subependymal layer. The ependyma is fully differentiated, with a monolayer of uniform cells, after 32 to 34 gestational weeks. We observed a wide spectrum of ependymal pathological changes in sudden death victims, such as desquamation, clusters of ependymal cells in the subventricular zone, radial glial cells, and the unusual presence of neurons within and over the ependymal lining. These alterations were significantly related to maternal smoking in pregnancy. Conclusions We conclude that in smoking mothers, nicotine and its derivatives easily reach the cerebrospinal fluid in the fetus, immediately causing ependymal damage. Consequently, we suggest that the ependyma should be examined in-depth first in victims of sudden fetal or infant death with mothers who smoke.
Directory of Open Access Journals (Sweden)
Giulia Ottaviani
2016-09-01
Full Text Available Crib death, or sudden infant death syndrome (SIDS, is the most frequent form of death in the first year of life, striking one baby in every 1,700–2,000. Yet despite advances in maternal-infant care, sudden intrauterine unexplained/unexpected death syndrome (SIUDS, has a six-eightfold greater incidence than that of SIDS. Frequent congenital abnormalities, likely morphological substrates for SIDS-SIUDS, were detected, mainly represented by alterations of the cardiac conduction system, such as accessory pathways and abnormal resorptive degeneration, and hypoplasia/agenesis of the vital brainstem structures. On the basis of these considerations, the new common definition of the SIDS-SIUDS complex is The sudden death of a fetus after the 25th gestational week or infant under one year of age which is unexpected by history and remains unexplained after a thorough case investigation, including examination of the death scene, performance of a general autopsy and examination of the fetal adnexa. Therefore, given that the general autopsy does not disclose any cause of death, a more in-depth histopathological analysis of the cardiac conduction system and autonomic nervous system by specialized pathologists will become necessary.
Transition from the adiabatic to the sudden limit in core-electron photoemission
Hedin, Lars; Michiels, John; Inglesfield, John
1998-12-01
Experimental results for core-electron photoemission Jk(ω) are often compared with the one-electron spectral function Ac(ɛk-ω), where ω is the photon energy, ɛk is the photoelectron energy, and the optical transition matrix elements are taken as constant. Since Jk(ω) is nonzero only for ɛk>0, we must actually compare it with Ac(ɛk-ω)θ(ɛk). For metals Ac(ω) is known to have a quasiparticle (QP) peak with an asymmetric power-law [theories of Mahan, Nozières, de Dominicis, Langreth, and others (MND)] singularity due to low-energy particle-hole excitations. The QP peak starts at the core-electron energy ɛc, and is followed by an extended satellite (shakeup) structure at smaller ω. For photon energies ω just above threshold, ωth=-ɛc, Ac(ɛk-ω)θ(ɛk) as a function of ɛk (ω constant) is cut just behind the quasiparticle peak, and neither the tail of the MND line nor the plasmon satellites are present. The sudden (high-energy) limit is given by a convolution of Ac(ω) and a loss function, i.e., by the Berglund-Spicer two-step expression. Thus Ac(ω) alone does not give the correct photoelectron spectrum, neither at low nor at high energies. We present an extension of the quantum-mechanical (QM) models developed earlier by Inglesfield, and by Bardyszewski and Hedin to calculate Jk(ω). It includes recoil and damping, as well as shakeup effects and extrinsic losses, is exact in the high-energy limit, and allows calculations of Jk(ω) including the MND line and multiple plasmon losses. The model, which involves electrons coupled to quasibosons, is motivated by detailed arguments. As an illustration we have made quantitative calculations for a semi-infinite jellium with the density of aluminum metal and an embedded atom. The coupling functions (fluctuation potentials) between the electron and the quasibosons are related to the random-phase-approximation dielectric function, and different levels of approximations are evaluated numerically. The differences
Contrast-enhanced MR imaging of the endolymphatic sac in patients with sudden hearing loss
International Nuclear Information System (INIS)
Naganawa, Shinji; Koshikawa, Tokiko; Fukatsu, Hiroshi; Ishigaki, Takeo; Nakashima, Tsutomu; Ichinose, Nobuyasu
2002-01-01
Our objective was to evaluate the frequency of contrast enhancement of the endolymphatic sac in patients with sudden hearing loss. Forty consecutive patients with sudden sensorineural hearing loss (20 males and 20 females; age range 11-82 years), 40 age-matched control subjects, and 5 patients with Meniere's disease were examined using the same imaging protocol on a 1.5-T MR system. Pre- and post-contrast-enhanced T1-weighted 3D spoiled gradient-echo sequence (3D SPGR; TR/TE=23/10 ms, no. of excitations=1, flip angle=30 ) images were obtained using a voxel size of 0.6 x 0.7 x 0.8 mm 3 . Contrast enhancement in the area of the endolymphatic sac was assessed by two radiologists, and the frequency of contrast enhancement was compared between the three study groups. Enhancement of the ipsilateral endolymphatic sac was observed in 30 of the 40 patients with sudden hearing loss (75%). Twenty of these 30 patients also showed enhancement on the contralateral side, and 1 patient showed enhancement only on the contralateral side. Only 1 of the 5 patients with Meniere's disease showed enhancement. Nine of the 40 control subjects (22.5%) showed enhancement (bilateral enhancement in 5 subjects, unilateral in 4). The frequency of enhancement in patients with sudden hearing loss was significantly higher than that in control subjects (P<0.0001) or patients with Meniere's disease (P<0.05). The frequency of contrast enhancement of the endolymphatic sac is significantly increased in patients with sudden hearing loss, but further study is necessary to clarify the relationship between this finding and the pathophysiology of sudden hearing loss. (orig.)
Son, Myoung Kyun; Ki, Chang-Seok; Park, Seung-Jung; Huh, June; Kim, June Soo; On, Young Keun
2013-07-01
Mutation or common intronic variants in cardiac ion channel genes have been suggested to be associated with sudden cardiac death caused by idiopathic ventricular tachyarrhythmia. This study aimed to find mutations in cardiac ion channel genes of Korean sudden cardiac arrest patients with structurally normal heart and to verify association between common genetic variation in cardiac ion channel and sudden cardiac arrest by idiopathic ventricular tachyarrhythmia in Koreans. Study participants were Korean survivors of sudden cardiac arrest caused by idiopathic ventricular tachycardia or fibrillation. All coding exons of the SCN5A, KCNQ1, and KCNH2 genes were analyzed by Sanger sequencing. Fifteen survivors of sudden cardiac arrest were included. Three male patients had mutations in SCN5A gene and none in KCNQ1 and KCNH2 genes. Intronic variant (rs2283222) in KCNQ1 gene showed significant association with sudden cardiac arrest (OR 4.05). Four male sudden cardiac arrest survivors had intronic variant (rs11720524) in SCN5A gene. None of female survivors of sudden cardiac arrest had SCN5A gene mutations despite similar frequencies of intronic variants between males and females in 55 normal controls. Common intronic variant in KCNQ1 gene is associated with sudden cardiac arrest caused by idiopathic ventricular tachyarrhythmia in Koreans.
International Nuclear Information System (INIS)
Arbo, D.G.; Toekesi, K.; Miraglia, J.E.; FCEN, University of Buenos Aires
2008-01-01
Complete text of publication follows. We presented a theoretical study of the ionization of hydrogen atoms as a result of the interaction with an ultrashort external electric field. Doubly-differential momentum distributions and angular momentum distributions of ejected electrons calculated in the framework of the Coulomb-Volkov and strong field approximations, as well as classical calculations are compared with the exact solution of the time dependent Schroedinger equation. We have shown that the Coulomb-Volkov approximation (CVA) describes the quantum atomic ionization probabilities exactly when the external field is described by a sudden momentum transfer [1]. The velocity distribution of emitted electrons right after ionization by a sudden momentum transfer is given through the strong field approximation (SFA) within both the CVA and CTMC methods. In this case, the classical and quantum time dependent evolutions of an atom subject to a sudden momentum transfer are identical. The difference between the classical and quantum final momentum distributions resides in the time evolution of the escaping electron under the subsequent action of the Coulomb field. Furthermore, classical mechanics is incapable of reproducing the quantum angular momentum distribution due to the improper initial radial distribution used in the CTMC calculations, i.e., the microcanonical ensemble. We find that in the limit of high momentum transfer, based on the SFA, there is a direct relation between the cylindrical radial distribution dP/dρ and the final angular momentum distribution dP/dL. This leads to a close analytical expression for the partial wave populations (dP/dL) SFA-Q given by dP SFA-Q / dL = 4Z 3 L 2 / (Δp) 3 K 1 (2ZL/Δp) which, together with the prescription L = l + 1/2, reproduces quite accurately the quantum (CVA) results. Considering the inverse problem, knowing the final angular momentum distribution can lead to the inference of the initial probability distribution
Sudden Cardiac Death of a Body Packer Due to Cocaine Cardiotoxicity
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Parthasarathi Pramanik
2016-01-01
Full Text Available This article presents a case of sudden cardiac death due to the effects of cocaine concealed in the body of a male drug smuggler in his 40s, a so-called body packer. A total of 57 body packets filled with cocaine powder were discovered in his body cavities. The detailed autopsy examination, including histopathology and toxicology findings, is discussed with the aim of describing the mechanism of cocaine intoxication in the body packer and an analysis of cocaine-induced cardiotoxicity and sudden death.
DEFF Research Database (Denmark)
Risgaard, Bjarke; Waagstein, Kristine; Winkel, Bo Gregers
2015-01-01
Introduction: Psychiatric patients have premature mortality compared to the general population. The incidence of sudden cardiac death (SCD) in psychiatric patients is unknown in a nationwide setting. The aim of this study was to compare nationwide SCD incidence rates in young individuals with and......Introduction: Psychiatric patients have premature mortality compared to the general population. The incidence of sudden cardiac death (SCD) in psychiatric patients is unknown in a nationwide setting. The aim of this study was to compare nationwide SCD incidence rates in young individuals...
[Sudden death in Versailles: A review of a cardiovascular treatrise by Dionis (1710)].
Charlier, P
2018-02-01
In 1710, the surgeon Pierre Dionis publishes a Dissertation on sudden death. Echoing and expanding the work of his Roman colleague Jean Marie Lancisi, he describes and analyzes dozens of cases of sudden death observed by him. A large number of cases was followed by autopsies allowing clinicopathological confrontation. Are proposed causes of death (pulmonary embolism, myocardial infarction, hemorrhagic stroke, arterial rupture, etc.), pathophysiological mechanisms based on the ancient theory of humors, and preventive actions to avoid these unexpected deaths. In this article, we oppose these old data to those of current literature. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
Excess sudden cardiac deaths after short-term clarithromycin administration in the CLARICOR trial
DEFF Research Database (Denmark)
Winkel, Per; Hilden, J; Hansen, Jørgen Fischer
2011-01-01
Objectives: To elucidate potential mechanisms for the clarithromycin-induced excess mortality observed in the CLARICOR trial during 2.6 year follow-up of patients with stable coronary artery disease. Methods: Cox analyses using out-of-hospital death as a proxy for sudden death compared to in-hospital...... CV death in patients not on statins at trial entry (HR: 2.61, 95% CI: 1.69–4.05, p administration was significantly associated with increased risk of sudden CV death in stable...
Takayasu Arteritis of the Coronary Arteries Presenting as Sudden Death in a White Teenager.
Hlavaty, Leigh; Diaz, Francisco; Sung, LokMan
2015-09-01
Takayasu arteritis is a rare disease that expresses chronic, large vessel inflammation. The etiology remains unclear and its presentation depends on the affected arteries. With coronary artery involvement, manifestations range from chest pain and shortness of breath to sudden death. We report a case of a 15-year-old white girl who presented with syncope immediately before passing. On autopsy, all 3 major coronary arteries grossly contained multiple proximal lesions that were consistent with Takayasu arteritis, microscopically. Takayasu arteritis solely affecting multiple coronary arteries is exceedingly rare. This report discusses the significance of coronary involvement in Takayasu arteritis at autopsy and sudden death.
Trajectory averaging for stochastic approximation MCMC algorithms
Liang, Faming
2010-10-01
The subject of stochastic approximation was founded by Robbins and Monro [Ann. Math. Statist. 22 (1951) 400-407]. After five decades of continual development, it has developed into an important area in systems control and optimization, and it has also served as a prototype for the development of adaptive algorithms for on-line estimation and control of stochastic systems. Recently, it has been used in statistics with Markov chain Monte Carlo for solving maximum likelihood estimation problems and for general simulation and optimizations. In this paper, we first show that the trajectory averaging estimator is asymptotically efficient for the stochastic approximation MCMC (SAMCMC) algorithm under mild conditions, and then apply this result to the stochastic approximation Monte Carlo algorithm [Liang, Liu and Carroll J. Amer. Statist. Assoc. 102 (2007) 305-320]. The application of the trajectory averaging estimator to other stochastic approximationMCMC algorithms, for example, a stochastic approximation MLE algorithm for missing data problems, is also considered in the paper. © Institute of Mathematical Statistics, 2010.
'LTE-diffusion approximation' for arc calculations
International Nuclear Information System (INIS)
Lowke, J J; Tanaka, M
2006-01-01
This paper proposes the use of the 'LTE-diffusion approximation' for predicting the properties of electric arcs. Under this approximation, local thermodynamic equilibrium (LTE) is assumed, with a particular mesh size near the electrodes chosen to be equal to the 'diffusion length', based on D e /W, where D e is the electron diffusion coefficient and W is the electron drift velocity. This approximation overcomes the problem that the equilibrium electrical conductivity in the arc near the electrodes is almost zero, which makes accurate calculations using LTE impossible in the limit of small mesh size, as then voltages would tend towards infinity. Use of the LTE-diffusion approximation for a 200 A arc with a thermionic cathode gives predictions of total arc voltage, electrode temperatures, arc temperatures and radial profiles of heat flux density and current density at the anode that are in approximate agreement with more accurate calculations which include an account of the diffusion of electric charges to the electrodes, and also with experimental results. Calculations, which include diffusion of charges, agree with experimental results of current and heat flux density as a function of radius if the Milne boundary condition is used at the anode surface rather than imposing zero charge density at the anode
Semiclassical initial value approximation for Green's function.
Kay, Kenneth G
2010-06-28
A semiclassical initial value approximation is obtained for the energy-dependent Green's function. For a system with f degrees of freedom the Green's function expression has the form of a (2f-1)-dimensional integral over points on the energy surface and an integral over time along classical trajectories initiated from these points. This approximation is derived by requiring an integral ansatz for Green's function to reduce to Gutzwiller's semiclassical formula when the integrations are performed by the stationary phase method. A simpler approximation is also derived involving only an (f-1)-dimensional integral over momentum variables on a Poincare surface and an integral over time. The relationship between the present expressions and an earlier initial value approximation for energy eigenfunctions is explored. Numerical tests for two-dimensional systems indicate that good accuracy can be obtained from the initial value Green's function for calculations of autocorrelation spectra and time-independent wave functions. The relative advantages of initial value approximations for the energy-dependent Green's function and the time-dependent propagator are discussed.
Approximate Bayesian evaluations of measurement uncertainty
Possolo, Antonio; Bodnar, Olha
2018-04-01
The Guide to the Expression of Uncertainty in Measurement (GUM) includes formulas that produce an estimate of a scalar output quantity that is a function of several input quantities, and an approximate evaluation of the associated standard uncertainty. This contribution presents approximate, Bayesian counterparts of those formulas for the case where the output quantity is a parameter of the joint probability distribution of the input quantities, also taking into account any information about the value of the output quantity available prior to measurement expressed in the form of a probability distribution on the set of possible values for the measurand. The approximate Bayesian estimates and uncertainty evaluations that we present have a long history and illustrious pedigree, and provide sufficiently accurate approximations in many applications, yet are very easy to implement in practice. Differently from exact Bayesian estimates, which involve either (analytical or numerical) integrations, or Markov Chain Monte Carlo sampling, the approximations that we describe involve only numerical optimization and simple algebra. Therefore, they make Bayesian methods widely accessible to metrologists. We illustrate the application of the proposed techniques in several instances of measurement: isotopic ratio of silver in a commercial silver nitrate; odds of cryptosporidiosis in AIDS patients; height of a manometer column; mass fraction of chromium in a reference material; and potential-difference in a Zener voltage standard.
Multilevel weighted least squares polynomial approximation
Haji-Ali, Abdul-Lateef
2017-06-30
Weighted least squares polynomial approximation uses random samples to determine projections of functions onto spaces of polynomials. It has been shown that, using an optimal distribution of sample locations, the number of samples required to achieve quasi-optimal approximation in a given polynomial subspace scales, up to a logarithmic factor, linearly in the dimension of this space. However, in many applications, the computation of samples includes a numerical discretization error. Thus, obtaining polynomial approximations with a single level method can become prohibitively expensive, as it requires a sufficiently large number of samples, each computed with a sufficiently small discretization error. As a solution to this problem, we propose a multilevel method that utilizes samples computed with different accuracies and is able to match the accuracy of single-level approximations with reduced computational cost. We derive complexity bounds under certain assumptions about polynomial approximability and sample work. Furthermore, we propose an adaptive algorithm for situations where such assumptions cannot be verified a priori. Finally, we provide an efficient algorithm for the sampling from optimal distributions and an analysis of computationally favorable alternative distributions. Numerical experiments underscore the practical applicability of our method.
Smooth function approximation using neural networks.
Ferrari, Silvia; Stengel, Robert F
2005-01-01
An algebraic approach for representing multidimensional nonlinear functions by feedforward neural networks is presented. In this paper, the approach is implemented for the approximation of smooth batch data containing the function's input, output, and possibly, gradient information. The training set is associated to the network adjustable parameters by nonlinear weight equations. The cascade structure of these equations reveals that they can be treated as sets of linear systems. Hence, the training process and the network approximation properties can be investigated via linear algebra. Four algorithms are developed to achieve exact or approximate matching of input-output and/or gradient-based training sets. Their application to the design of forward and feedback neurocontrollers shows that algebraic training is characterized by faster execution speeds and better generalization properties than contemporary optimization techniques.
Modified semiclassical approximation for trapped Bose gases
International Nuclear Information System (INIS)
Yukalov, V.I.
2005-01-01
A generalization of the semiclassical approximation is suggested allowing for an essential extension of its region of applicability. In particular, it becomes possible to describe Bose-Einstein condensation of a trapped gas in low-dimensional traps and in traps of low confining dimensions, for which the standard semiclassical approximation is not applicable. The result of the modified approach is shown to coincide with purely quantum-mechanical calculations for harmonic traps, including the one-dimensional harmonic trap. The advantage of the semiclassical approximation is in its simplicity and generality. Power-law potentials of arbitrary powers are considered. The effective thermodynamic limit is defined for any confining dimension. The behavior of the specific heat, isothermal compressibility, and density fluctuations is analyzed, with an emphasis on low confining dimensions, where the usual semiclassical method fails. The peculiarities of the thermodynamic characteristics in the effective thermodynamic limit are discussed
The binary collision approximation: Background and introduction
International Nuclear Information System (INIS)
Robinson, M.T.
1992-08-01
The binary collision approximation (BCA) has long been used in computer simulations of the interactions of energetic atoms with solid targets, as well as being the basis of most analytical theory in this area. While mainly a high-energy approximation, the BCA retains qualitative significance at low energies and, with proper formulation, gives useful quantitative information as well. Moreover, computer simulations based on the BCA can achieve good statistics in many situations where those based on full classical dynamical models require the most advanced computer hardware or are even impracticable. The foundations of the BCA in classical scattering are reviewed, including methods of evaluating the scattering integrals, interaction potentials, and electron excitation effects. The explicit evaluation of time at significant points on particle trajectories is discussed, as are scheduling algorithms for ordering the collisions in a developing cascade. An approximate treatment of nearly simultaneous collisions is outlined and the searching algorithms used in MARLOWE are presented
Self-similar continued root approximants
International Nuclear Information System (INIS)
Gluzman, S.; Yukalov, V.I.
2012-01-01
A novel method of summing asymptotic series is advanced. Such series repeatedly arise when employing perturbation theory in powers of a small parameter for complicated problems of condensed matter physics, statistical physics, and various applied problems. The method is based on the self-similar approximation theory involving self-similar root approximants. The constructed self-similar continued roots extrapolate asymptotic series to finite values of the expansion parameter. The self-similar continued roots contain, as a particular case, continued fractions and Padé approximants. A theorem on the convergence of the self-similar continued roots is proved. The method is illustrated by several examples from condensed-matter physics.
Ancilla-approximable quantum state transformations
Energy Technology Data Exchange (ETDEWEB)
Blass, Andreas [Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Gurevich, Yuri [Microsoft Research, Redmond, Washington 98052 (United States)
2015-04-15
We consider the transformations of quantum states obtainable by a process of the following sort. Combine the given input state with a specially prepared initial state of an auxiliary system. Apply a unitary transformation to the combined system. Measure the state of the auxiliary subsystem. If (and only if) it is in a specified final state, consider the process successful, and take the resulting state of the original (principal) system as the result of the process. We review known information about exact realization of transformations by such a process. Then we present results about approximate realization of finite partial transformations. We not only consider primarily the issue of approximation to within a specified positive ε, but also address the question of arbitrarily close approximation.
On Born approximation in black hole scattering
Batic, D.; Kelkar, N. G.; Nowakowski, M.
2011-12-01
A massless field propagating on spherically symmetric black hole metrics such as the Schwarzschild, Reissner-Nordström and Reissner-Nordström-de Sitter backgrounds is considered. In particular, explicit formulae in terms of transcendental functions for the scattering of massless scalar particles off black holes are derived within a Born approximation. It is shown that the conditions on the existence of the Born integral forbid a straightforward extraction of the quasi normal modes using the Born approximation for the scattering amplitude. Such a method has been used in literature. We suggest a novel, well defined method, to extract the large imaginary part of quasinormal modes via the Coulomb-like phase shift. Furthermore, we compare the numerically evaluated exact scattering amplitude with the Born one to find that the approximation is not very useful for the scattering of massless scalar, electromagnetic as well as gravitational waves from black holes.
Ancilla-approximable quantum state transformations
International Nuclear Information System (INIS)
Blass, Andreas; Gurevich, Yuri
2015-01-01
We consider the transformations of quantum states obtainable by a process of the following sort. Combine the given input state with a specially prepared initial state of an auxiliary system. Apply a unitary transformation to the combined system. Measure the state of the auxiliary subsystem. If (and only if) it is in a specified final state, consider the process successful, and take the resulting state of the original (principal) system as the result of the process. We review known information about exact realization of transformations by such a process. Then we present results about approximate realization of finite partial transformations. We not only consider primarily the issue of approximation to within a specified positive ε, but also address the question of arbitrarily close approximation
On transparent potentials: a Born approximation study
International Nuclear Information System (INIS)
Coudray, C.
1980-01-01
In the frame of the scattering inverse problem at fixed energy, a class of potentials transparent in Born approximation is obtained. All these potentials are spherically symmetric and are oscillating functions of the reduced radial variable. Amongst them, the Born approximation of the transparent potential of the Newton-Sabatier method is found. In the same class, quasi-transparent potentials are exhibited. Very general features of potentials transparent in Born approximation are then stated. And bounds are given for the exact scattering amplitudes corresponding to most of the potentials previously exhibited. These bounds, obtained at fixed energy, and for large values of the angular momentum, are found to be independent on the energy
The adiabatic approximation in multichannel scattering
International Nuclear Information System (INIS)
Schulte, A.M.
1978-01-01
Using two-dimensional models, an attempt has been made to get an impression of the conditions of validity of the adiabatic approximation. For a nucleon bound to a rotating nucleus the Coriolis coupling is neglected and the relation between this nuclear Coriolis coupling and the classical Coriolis force has been examined. The approximation for particle scattering from an axially symmetric rotating nucleus based on a short duration of the collision, has been combined with an approximation based on the limitation of angular momentum transfer between particle and nucleus. Numerical calculations demonstrate the validity of the new combined method. The concept of time duration for quantum mechanical collisions has also been studied, as has the collective description of permanently deformed nuclei. (C.F.)
Minimal entropy approximation for cellular automata
International Nuclear Information System (INIS)
Fukś, Henryk
2014-01-01
We present a method for the construction of approximate orbits of measures under the action of cellular automata which is complementary to the local structure theory. The local structure theory is based on the idea of Bayesian extension, that is, construction of a probability measure consistent with given block probabilities and maximizing entropy. If instead of maximizing entropy one minimizes it, one can develop another method for the construction of approximate orbits, at the heart of which is the iteration of finite-dimensional maps, called minimal entropy maps. We present numerical evidence that the minimal entropy approximation sometimes outperforms the local structure theory in characterizing the properties of cellular automata. The density response curve for elementary CA rule 26 is used to illustrate this claim. (paper)
Resummation of perturbative QCD by pade approximants
International Nuclear Information System (INIS)
Gardi, E.
1997-01-01
In this lecture I present some of the new developments concerning the use of Pade Approximants (PA's) for resuming perturbative series in QCD. It is shown that PA's tend to reduce the renormalization scale and scheme dependence as compared to truncated series. In particular it is proven that in the limit where the β function is dominated by the 1-loop contribution, there is an exact symmetry that guarantees invariance of diagonal PA's under changing the renormalization scale. In addition it is shown that in the large β 0 approximation diagonal PA's can be interpreted as a systematic method for approximating the flow of momentum in Feynman diagrams. This corresponds to a new multiple scale generalization of the Brodsky-Lepage-Mackenzie (BLM) method to higher orders. I illustrate the method with the Bjorken sum rule and the vacuum polarization function. (author)
Fast wavelet based sparse approximate inverse preconditioner
Energy Technology Data Exchange (ETDEWEB)
Wan, W.L. [Univ. of California, Los Angeles, CA (United States)
1996-12-31
Incomplete LU factorization is a robust preconditioner for both general and PDE problems but unfortunately not easy to parallelize. Recent study of Huckle and Grote and Chow and Saad showed that sparse approximate inverse could be a potential alternative while readily parallelizable. However, for special class of matrix A that comes from elliptic PDE problems, their preconditioners are not optimal in the sense that independent of mesh size. A reason may be that no good sparse approximate inverse exists for the dense inverse matrix. Our observation is that for this kind of matrices, its inverse entries typically have piecewise smooth changes. We can take advantage of this fact and use wavelet compression techniques to construct a better sparse approximate inverse preconditioner. We shall show numerically that our approach is effective for this kind of matrices.
Perturbation expansions generated by an approximate propagator
International Nuclear Information System (INIS)
Znojil, M.
1987-01-01
Starting from a knowledge of an approximate propagator R at some trial energy guess E 0 , a new perturbative prescription for p-plet of bound states and of their energies is proposed. It generalizes the Rayleigh-Schroedinger (RS) degenerate perturbation theory to the nondiagonal operators R (eliminates a RS need of their diagnolisation) and defines an approximate Hamiltonian T by mere inversion. The deviation V of T from the exact Hamiltonian H is assumed small only after a substraction of a further auxiliary Hartree-Fock-like separable ''selfconsistent'' potential U of rank p. The convergence is illustrated numerically on the anharmonic oscillator example
Approximate Inference and Deep Generative Models
CERN. Geneva
2018-01-01
Advances in deep generative models are at the forefront of deep learning research because of the promise they offer for allowing data-efficient learning, and for model-based reinforcement learning. In this talk I'll review a few standard methods for approximate inference and introduce modern approximations which allow for efficient large-scale training of a wide variety of generative models. Finally, I'll demonstrate several important application of these models to density estimation, missing data imputation, data compression and planning.
Unambiguous results from variational matrix Pade approximants
International Nuclear Information System (INIS)
Pindor, Maciej.
1979-10-01
Variational Matrix Pade Approximants are studied as a nonlinear variational problem. It is shown that although a stationary value of the Schwinger functional is a stationary value of VMPA, the latter has also another stationary value. It is therefore proposed that instead of looking for a stationary point of VMPA, one minimizes some non-negative functional and then one calculates VMPA at the point where the former has the absolute minimum. This approach, which we call the Method of the Variational Gradient (MVG) gives unambiguous results and is also shown to minimize a distance between the approximate and the exact stationary values of the Schwinger functional
Faster and Simpler Approximation of Stable Matchings
Directory of Open Access Journals (Sweden)
Katarzyna Paluch
2014-04-01
Full Text Available We give a 3 2 -approximation algorithm for finding stable matchings that runs in O(m time. The previous most well-known algorithm, by McDermid, has the same approximation ratio but runs in O(n3/2m time, where n denotes the number of people andm is the total length of the preference lists in a given instance. In addition, the algorithm and the analysis are much simpler. We also give the extension of the algorithm for computing stable many-to-many matchings.
APPROXIMATION OF PROBABILITY DISTRIBUTIONS IN QUEUEING MODELS
Directory of Open Access Journals (Sweden)
T. I. Aliev
2013-03-01
Full Text Available For probability distributions with variation coefficient, not equal to unity, mathematical dependences for approximating distributions on the basis of first two moments are derived by making use of multi exponential distributions. It is proposed to approximate distributions with coefficient of variation less than unity by using hypoexponential distribution, which makes it possible to generate random variables with coefficient of variation, taking any value in a range (0; 1, as opposed to Erlang distribution, having only discrete values of coefficient of variation.
On the dipole approximation with error estimates
Boßmann, Lea; Grummt, Robert; Kolb, Martin
2018-01-01
The dipole approximation is employed to describe interactions between atoms and radiation. It essentially consists of neglecting the spatial variation of the external field over the atom. Heuristically, this is justified by arguing that the wavelength is considerably larger than the atomic length scale, which holds under usual experimental conditions. We prove the dipole approximation in the limit of infinite wavelengths compared to the atomic length scale and estimate the rate of convergence. Our results include N-body Coulomb potentials and experimentally relevant electromagnetic fields such as plane waves and laser pulses.
Congruence Approximations for Entrophy Endowed Hyperbolic Systems
Barth, Timothy J.; Saini, Subhash (Technical Monitor)
1998-01-01
Building upon the standard symmetrization theory for hyperbolic systems of conservation laws, congruence properties of the symmetrized system are explored. These congruence properties suggest variants of several stabilized numerical discretization procedures for hyperbolic equations (upwind finite-volume, Galerkin least-squares, discontinuous Galerkin) that benefit computationally from congruence approximation. Specifically, it becomes straightforward to construct the spatial discretization and Jacobian linearization for these schemes (given a small amount of derivative information) for possible use in Newton's method, discrete optimization, homotopy algorithms, etc. Some examples will be given for the compressible Euler equations and the nonrelativistic MHD equations using linear and quadratic spatial approximation.
Hardness of approximation for strip packing
DEFF Research Database (Denmark)
Adamaszek, Anna Maria; Kociumaka, Tomasz; Pilipczuk, Marcin
2017-01-01
Strip packing is a classical packing problem, where the goal is to pack a set of rectangular objects into a strip of a given width, while minimizing the total height of the packing. The problem has multiple applications, for example, in scheduling and stock-cutting, and has been studied extensively......)-approximation by two independent research groups [FSTTCS 2016,WALCOM 2017]. This raises a questionwhether strip packing with polynomially bounded input data admits a quasi-polynomial time approximation scheme, as is the case for related twodimensional packing problems like maximum independent set of rectangles or two...
International Nuclear Information System (INIS)
Khare, V.; Kouri, D.J.; Hoffman, D.K.
1981-01-01
The occurrence of j/sub z/-preserving propensities in atom--linear molecule collisions is considered within the contexts of the quantum mechanical CS approximation and of a classical model collision system. The latter involves an impulsive interaction which is the extreme limit of the class of potentials for which the CS approximation is expected to be valid. The classical model results in exact conservation of j/sub z/ along a ''kinematic apse.'' Quantum mechanically, the CS approximation is reformulated in a manner that clearly shows the relationship between the l choice and the degree and direction of j/sub z/ preservation. Away from the forward direction, the simplest choice obeying time reversal symmetry l=(l-script+l')/2, is shown to result in a propensity for preserving j/sub z/ along a ''geometric apse'' which coincides with the kinematic apse in the energy sudden limit, and for nonenergy sudden systems only differs significantly from it close to the forward direction
Effect of passenger position on fear of danger experienced during sudden bus stops.
Aoki, Takeo; Uetake, Teruo; Shimoda, Masahiro
2009-06-01
The purpose of this study was to identify the effect of bus passengers' positions on their fear of danger when a bus stopped suddenly. A temporary bus running course with one bus stop was set up on the campus of the Tokyo University of Agriculture and Technology (TUAT). The bus ran the course 14 times with the bus stopping twice during the course, once at the bus stop and again just after re-starting from the bus stop. The driver was asked to brake more strongly than usual when stopping. Sixteen students (15 males and 1 female) between the ages of 18 and 21 years participated. In turn, all participants were asked to take 14 different postures in the bus. Participants were also asked to report their level of fear on a rating scale each time the bus stopped. The study showed that (1) passengers' fear of danger at the first sudden stop was typically higher than that at the second stop, (2) standing passengers who held hand straps experienced more fear than those who held fixed safety devices, (3) bus passengers sitting on the centre of the rear seat had a great risk of injury if the bus stopped suddenly, and (4) when passengers faced the window and stood transversely with respect to from the moving direction of the bus and the bus stopped suddenly, passengers' fear of danger was affected by the side of the bus on which they stood as well as which hand they used to grasp a safety device.
Sudden oak death: disease trends in Marin county plots after one year
Brice A. McPherson; David L. Wood; Andrew J. Storer; Nina Maggi Kelly; Richard B. Standiford
2002-01-01
Sudden oak death has emerged as a major threat to the oak forests of California. In oaks and tanoak, this disease complex consists of a previously unreported fungus-like pathogen, Phytophthora ramorum, insects (bark and ambrosia beetles), and a secondary fungus, Hypoxylon thouarsianum. Species monitored in this study were coast...
SUDDEN CARDIAC DEATH AND THE USE OF IMPLANTABLE CARDIOVERTER-DEFIBRILLATORS IN PEDIATRIC-PATIENTS
SILKA, MJ; KRON, J; DUNNIGAN, A; DICK, M; BINKBOELKENS, M; ERICKSON, CC; JEDEIKIN, R; WETZEL, GT; VANHARE, GF; CAMPBELL, R; WALSH, E; SAUL, JP; SCHAFFER, MS; KARPAWICH, P; VOGEL, RL; BENSON, DW; DEAL, B; SCAGLIOTTI, D; STERBA, R; HORDOF, AJ; KRONGRAD, E; KANTER, RJ; EPSTEIN, M; COHEN, M; BEDER, S; HAMILTON, R; FOURNIER, A; HUBBARD, J; CHRISTIANSEN, JL; JENNINGS, J; VILLAFANE, J; PORTER, CBJ; CASE, C; GILLETTE, PC; BELAND, M; KUGLER, JD; OCONNOR, BK; ALLENDER, H; HERNDON, SP; SMITH, RT; BURTON, D; KURER, CC; BYRUM, C; GUAM, WE; FRIEDMAN, R; PERRY, JC; SCOTT, W; MEHTA, AV; PICKHOFF, AS; FISH, F; YEAGER, S; KAWABORI, [No Value; TRIPPLE, M; ROSENFELD, LE
Background. During the past decade. the implantable cardioverter-defibrillator (ICD) has emerged as the primary therapeutic option for survivors of sudden cardiac death (SCD). Investigation of the clinical efficacy of these devices has primarily assessed outcome in adults with coronary artery
Damage Detection on Sudden Stiffness Reduction Based on Discrete Wavelet Transform
Directory of Open Access Journals (Sweden)
Bo Chen
2014-01-01
Full Text Available The sudden stiffness reduction in a structure may cause the signal discontinuity in the acceleration responses close to the damage location at the damage time instant. To this end, the damage detection on sudden stiffness reduction of building structures has been actively investigated in this study. The signal discontinuity of the structural acceleration responses of an example building is extracted based on the discrete wavelet transform. It is proved that the variation of the first level detail coefficients of the wavelet transform at damage instant is linearly proportional to the magnitude of the stiffness reduction. A new damage index is proposed and implemented to detect the damage time instant, location, and severity of a structure due to a sudden change of structural stiffness. Numerical simulation using a five-story shear building under different types of excitation is carried out to assess the effectiveness and reliability of the proposed damage index for the building at different damage levels. The sensitivity of the damage index to the intensity and frequency range of measurement noise is also investigated. The made observations demonstrate that the proposed damage index can accurately identify the sudden damage events if the noise intensity is limited.
Czech Academy of Sciences Publication Activity Database
Plavcová, Eva; Kyselý, Jan
2010-01-01
Roč. 54, č. 5 (2010), s. 539-551 ISSN 0020-7128 R&D Projects: GA ČR GA205/07/1254 Institutional research plan: CEZ:AV0Z30420517 Keywords : Mortality * Sudden change * Air temperature * Air pressure * Atmospheric front * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.805, year: 2010
Matteo Garbelotto; David M. Rizzo; Katie Hayden; Monica Meija-Chang; Jennifer M. Davidson; Steven Tjosvold
2002-01-01
Sudden oak death (SOD) has been shown to be caused by a new species of Phytophthora, P. ramorum. A basic understanding of the genetics of P. ramorum is critical to any management strategy. We have initiated a number of studies to examine species concepts, population biology and mating behavior of the pathogen....
Brian L. Anacker; Nathan E. Rank; Daniel Hüberli; Matteo Garbelotto; Sarah Gordon; Rich Whitkus; Tami Harnik; Matthew Meshriy; Lori Miles; Ross K. Meentemeyer
2008-01-01
Sudden oak death, caused by the water mold Phytophthora ramorum, is a plant disease responsible for the death of hundreds of thousands of oak and tanoak trees. Some foliar hosts play a major role in the epidemiology of this disease. Upon infection by P. ramorum, these foliar hosts express non-fatal leaf lesions from which large...
Sudden cardiac death in multiple sclerosis caused by active demyelination of the medulla oblongata
Hengstman, G.J.D.; Kusters, B.
2011-01-01
Cardiovascular autonomic dysfunction is not uncommon in multiple sclerosis (MS) and is related to the involvement of the vegetative areas of cardiac innervations in the medulla oblongata. It has been suggested that this may contribute to the occurrence of sudden death in MS. In this case report, we
Sports and Marfan Syndrome: Awareness and Early Diagnosis Can Prevent Sudden Death.
Salim, Mubadda A.; Alpert, Bruce S.
2001-01-01
Physicians who work with athletes play an important role in preventing sudden death related to physical activity in people who have Marfan syndrome. Flagging those who have the physical stigmata and listening for certain cardiac auscultation sounds are early diagnostic keys that can help prevent deaths. People with Marfan syndrome should be…
Meijler, F.L.; Tweel, I. van der; Herbschleb, J.N.; Hauer, R.N.W.; Robles de Medina, E.O.
A short refractory period of the accessory pathway is considered a major threat for sudden death in patients with Wolff-Parkinson-White syndrome and atrial fibrillation. RR interval and QRS signal analysis together with signal analysis of a bipolar high right atrial electrogram were obtained in six
Burden of sudden cardiac death in persons aged 1 to 49 years
DEFF Research Database (Denmark)
Risgaard, Bjarke; Winkel, Bo Gregers; Jabbari, Reza
2014-01-01
: All deaths in persons aged 1 to 49 years were included in 2007 to 2009. Death certificates were reviewed by 2 physicians. History of previous admissions to hospital was assessed, and discharge summaries were read. Sudden unexpected death cases were identified and autopsy reports were collected...
Sudden Cardiac arrest Risk profile in a group of amateur level ...
African Journals Online (AJOL)
... males and females in this group of university basketball players showed varying signs of SCA risk, with the overall risk being reasonably low, albeit abnormalities were highlighted in some and Marfanoid characteristics were clearly evident in others. Key words: Sudden cardiac arrest; Basketball players, Marfan syndrome; ...
Sudden gains in Cognitive Therapy and Interpersonal Psychotherapy for adult depression
Lemmens, L.H.J.M.; DeRubeis, R.J.; Arntz, A.; Peeters, F.P.M.L.; Huibers, M.J.H.
OBJECTIVE: We examined the rates, baseline predictors and clinical impact of sudden gains in a randomized comparison of individual Cognitive Therapy (CT) and Interpersonal Psychotherapy (IPT) for adult depression. METHOD: 117 depressed outpatients received 16-20 sessions of either CT or IPT.
Sudden gains in Cognitive Therapy and Interpersonal Psychotherapy for adult depression.
Lemmens, L.H.; DeRubeis, R.J.; Arntz, A.; Peeters, F.P.; Huibers, M.J.H.
2016-01-01
Objective: We examined the rates, baseline predictors and clinical impact of sudden gains in a randomized comparison of individual Cognitive Therapy (CT) and Interpersonal Psychotherapy (IPT) for adult depression. Method: 117 depressed outpatients received 16-20 sessions of either CT or IPT.
A.W. Hoes (Arno)
1992-01-01
textabstractThe studies described in this thesis focus on the possible relationship between the use of non-potassium sparing diuretics and the occurrence of sudden cardiac death in hypertensive patients. To study this potential adverse drug reaction several methods were applied, including
Sudden Oak Death in redwood forests: vegetation dynamics in the wake of tanoak decline
Benjamin Ramage; Kevin O’Hara
2010-01-01
Numerous lines of inquiry have concluded that tanoak (Lithocarpus densiflorus) will continue to experience drastic population declines and may even disappear entirely from redwood (Sequoia sempervirens) forests as a result of the exotic disease sudden oak death (SOD) (Maloney and others 2005, McPherson and others 2005,...
Assessing Methods to Protect Susceptible Oak and Tanoak Stands from Sudden Oak Death
Tedmund Swiecki; Elizabeth Bernhardt
2010-01-01
Landowners and managers have been seeking ways to protect susceptible oak (Quercus) species and tanoak (Lithocarpus densiflorus) from sudden oak death (SOD) caused by Phytophthora ramorum. Because disease epidemiology differs between tanoaks and susceptible oaks, we are testing different control strategies...
Evaluation of HIV protease inhibitor use and the risk of sudden death or nonhemorrhagic stroke
DEFF Research Database (Denmark)
Worm, S W; Kamara, D A; Reiss, P
2012-01-01
Concerns have arisen about possible effects of protease inhibitors (PIs) on cardiac conductivity. We found no significant association between current or recent PI exposure and sudden death or nonhemorrhagic stroke (adjusted rate ratio, 1.22; 95% confidence interval, .95-1.57), whereas cumulative...
Contribution of inherited heart disease to sudden cardiac death in childhood
Hofman, Nynke; Tan, Hanno L.; Clur, Sally-Ann; Alders, Mariel; van Langen, Irene M.; Wilde, Arthur A. M.
2007-01-01
BACKGROUND. In children aged 1 to 18 years, the causes of sudden cardiac death may remain unresolved when autopsy results are negative. Because inherited cardiac diseases are likely, cardiologic and genetic investigations of relatives may still yield the diagnosis in these cases. Moreover, these
Sudden Gains in Cognitive Therapy and Interpersonal Therapy for Social Anxiety Disorder
Bohn, Christiane; Aderka, Idan M.; Schreiber, Franziska; Stangier, Ulrich; Hofmann, Stefan G.
2013-01-01
Objective: The present study examined the effects of sudden gains on treatment outcome in a randomized controlled trial including individual cognitive therapy (CT) and interpersonal therapy (IPT) for social anxiety disorder (SAD). Method: Participants were 67 individuals with SAD who received 16 treatment sessions. Symptom severity at each session…
Managing redwood ecosystems using Sudden Oak Death as a silvicultural tool
Frederick D. Euphrat
2015-01-01
In response to the wave of sudden oak death (SOD), caused by Phytophthora ramorum, sweeping the redwood forest ecosystems of California's North Coast, the role of foresters and other ecosystem managers is being tested. On Bear Flat Tree Farm, near Healdsburg, California, Forest, Soil & Water, Inc. (FSW) has conducted a multi-year,...
van der Werf, Christian; Onderwater, Astrid T.; van Langen, Irene M.; Smets, Ellen M. A.
2014-01-01
Relatives of young sudden cardiac death (SCD) victims are at increased risk of carrying a potentially fatal inherited cardiac disease. Hence, it is recommended to perform an autopsy on the victim and to refer his or her relatives to a cardiogenetics clinic for a full evaluation to identify those at
Evidence of the dynamic response of housing values to a sudden oak death infestation
Kent F. Kovacs; Thomas P. Holmes; Jeffrey E. Englin; Janice. Alexander
2010-01-01
Sudden oak death (SOD), caused by the non-indigenous forest pathogen Phytophthora ramorum, causes substantial mortality in coast live oak (Quercus agrifolia) and several other oak species on the Pacific Coast of the United States. Quasi-experimental hedonic models examine the effect of SOD on property...