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1

Crop Classification Using Short-Revisit Multitemporal SAR Data  

Microsoft Academic Search

Classification of crops and other land cover types is an important application of both optical\\/infrared and SAR satel- lite data. It is already an import application of present satellite sys- tems, as it will be for planned missions, such as the Sentinels. An airborne SAR data set with a short revisit time acquired by the German ESAR system during the

Henning Skriver; Francesco Mattia; Giuseppe Satalino; Anna Balenzano; Valentijn R. N. Pauwels; Niko E. C. Verhoest; Malcolm Davidson

2011-01-01

2

Short Communication: Earth is (mostly) flat, but mountains dominate global denudation: apportionment of the continental mass flux over millennial time scales, revisited  

NASA Astrophysics Data System (ADS)

Carbon dioxide consumption by silicate mineral weathering and the subsequent precipitation of carbonate sediments sequesters CO2 over geologic timescales. The rate of this carbon sequestration is coupled to rates of continental erosion, which exposes fresh minerals to weathering. Steep mountain landscapes represent a small fraction of continental surfaces but contribute disproportionately to global erosion rates. However, the relative contributions of Earth's much vaster, but more slowly eroding, plains and hills remain the subject of debate. Recently, Willenbring et al. (2013) analyzed a compilation of denudation rates and topographic gradients and concluded that low-gradient regions dominate global denudation fluxes and silicate weathering rates. Here, we show that Willenbring et al. (2003) topographic and statistical analyses were subject to methodological errors that affected their conclusions. We correct these errors, and reanalyze their denudation rate and topographic data. In contrast to the results of Willenbring et al. (2013), we find that the denudation flux from the steepest 10% of continental topography nearly equals the flux from the other 90% of the continental surface combined. This new analysis implies global denudation fluxes of ∼23 Gt yr-1, roughly five times the value reported in Willenbring et al. (2013) and closer to previous estimates found elsewhere in the literature. Although low-gradient landscapes make up a small proportion of the global fluxes, they remain important because of the human reliance, and impact, on these vast areas.

Willenbring, J. K.; Codilean, A. T.; Ferrier, K. L.; McElroy, B.; Kirchner, J. W.

2014-01-01

3

The role of variety seeking in short and long run revisit intentions in holiday destinations  

Microsoft Academic Search

Purpose – The main purpose of the present paper is to identify the differences in the antecedents of holiday destinations revisit intentions in the short and long run. Specifically, this work analyzes the influence of specific variety seeking, perceived value, destination image, satisfaction, switching costs and past switching behavior. Design\\/methodology\\/approach – This is a quantitative study and the authors collected

J. Enrique Bigné; Isabel Sánchez; Luisa Andreu

2009-01-01

4

Short Time Force Measurement System.  

National Technical Information Service (NTIS)

The development of the SFS (Short time Force and moment measurement System) is considered. It enables measurement of aerodynamic forces and moments at testing times of less than 10 ms. This is required for measurements in high enthalpy shock tunnels to si...

J. Mertens K. Koenig

1991-01-01

5

Cosmic time dilation: The clock paradox revisited  

NASA Astrophysics Data System (ADS)

The relativistic time dilation is reviewed in a cosmological context. We show that a clock or twin paradox does not arise if cosmic time is properly taken into account. The receding galaxy background provides a unique frame of reference, and the proper times of geodesic as well as accelerated observers can be linked to the universal cosmic time parameter. This suggests to compare the proper time differentials of the respective observers by determining their state of motion in the galaxy grid. In this way, each observer can figure out whether his proper time is dilated or contracted relative to any other. In particular one can come to unambiguous conclusions on the aging of uniformly moving observers, without reference to asymmetries in measurement procedures or accelerations they may have undergone.

Tomaschitz, Roman

2004-05-01

6

Tunneling times and the Hartman effect revisited.  

National Technical Information Service (NTIS)

In a recent review paper we proposed, within conventional quantum mechanics, new definitions for the sub-barrier tunnelling and reflection times. Aims of the present paper are: presenting and analysing the results of various numerical calculations (based ...

V. S. Olkhovsky E. Recami F. Raciti A. K. Zaichenko

1995-01-01

7

The Cagniard method in complex time revisited  

SciTech Connect

The Cagniard-de Hoop method is ideally suited to the analysis of wave propagation problems in stratified media. The method applies to the integral transform representation of the solution in the transform variables (s,p) dual of the time and transverse distance. The objective of the method is to make the p-integral take the form of a forward Laplace transform, so that the cascade of the two integrals can be identified as a forward and inverse transform, thereby making the actual integration unnecessary. Typically, the method is applied to an integral that represents one body wave plus other types of waves. In this approach, the saddle point of w(p) that produces the body wave plays a crucial role because it is always a branch point of the integrand in the {tau}-domain integral. Furthermore, the paths of steepest ascent from the saddlepoint are always the tails of the Cagniard path along which w(p) {yields} {infinity}. This motivates the definition of a primary p-domain-the domain between the imaginary axis and the steepest descent paths- and its image in the {tau}-domain-the primary {tau}-domain. In terms of these regions, singularities in the primary p-domain have images in the primary {tau}-domain and the deformation of contour onto the real axis in the {tau}-domain must include contributions from these singularities. In developing the method the authors examine the transformation from a frequency domain representation of the solution (w) to a Laplace representation (s). Many users start from the frequency domain representation of solutions of wave propagation problems. There are issues of movement of singularities under the transformation from w to s to be concerned with here. They discuss this anomaly in the context of the Sommerfield half-plane problem. 15 refs., 10 figs.

Bleistein, N.; Cohen, J.K.

1991-03-01

8

Girl Number 20 Revisited: Feminist Literacies in New Hard Times  

ERIC Educational Resources Information Center

This paper revisits the question of "voice" in the context of neo-liberal social and educational reform. "Voice" has been one of the key concepts of feminist and critical pedagogies in the theory and practice of producing social transformation. I argue in this paper, that the political effectiveness of this concept needs to be reconsidered at a…

Gonick, Marnina

2007-01-01

9

Short-term retention of relational memory in amnesia revisited: accurate performance depends on hippocampal integrity  

PubMed Central

Traditionally, it has been proposed that the hippocampus and adjacent medial temporal lobe cortical structures are selectively critical for long-term declarative memory, which entails memory for inter-item and item-context relationships. Whether the hippocampus might also contribute to short-term retention of relational memory representations has remained controversial. In two experiments, we revisit this question by testing memory for relationships among items embedded in scenes using a standard working memory trial structure in which a sample stimulus is followed by a brief delay and the corresponding test stimulus. In each experimental block, eight trials using different exemplars of the same scene were presented. The exemplars contained the same items but with different spatial relationships among them. By repeating the pictures across trials, any potential contributions of item or scene memory to performance were minimized, and relational memory could be assessed more directly than has been done previously. When test displays were presented, participants indicated whether any of the item-location relationships had changed. Then, regardless of their responses (and whether any item did change its location), participants indicated on a forced-choice test, which item might have moved, guessing if necessary. Amnesic patients were impaired on the change detection test, and were frequently unable to specify the change after having reported correctly that a change had taken place. Comparison participants, by contrast, frequently identified the change even when they failed to report the mismatch, an outcome that speaks to the sensitivity of the change specification measure. These results confirm past reports of hippocampal contributions to short-term retention of relational memory representations, and suggest that the role of the hippocampus in memory has more to do with relational memory requirements than the length of a retention interval.

Yee, Lydia T. S.; Hannula, Deborah E.; Tranel, Daniel; Cohen, Neal J.

2014-01-01

10

Short-term retention of relational memory in amnesia revisited: accurate performance depends on hippocampal integrity.  

PubMed

Traditionally, it has been proposed that the hippocampus and adjacent medial temporal lobe cortical structures are selectively critical for long-term declarative memory, which entails memory for inter-item and item-context relationships. Whether the hippocampus might also contribute to short-term retention of relational memory representations has remained controversial. In two experiments, we revisit this question by testing memory for relationships among items embedded in scenes using a standard working memory trial structure in which a sample stimulus is followed by a brief delay and the corresponding test stimulus. In each experimental block, eight trials using different exemplars of the same scene were presented. The exemplars contained the same items but with different spatial relationships among them. By repeating the pictures across trials, any potential contributions of item or scene memory to performance were minimized, and relational memory could be assessed more directly than has been done previously. When test displays were presented, participants indicated whether any of the item-location relationships had changed. Then, regardless of their responses (and whether any item did change its location), participants indicated on a forced-choice test, which item might have moved, guessing if necessary. Amnesic patients were impaired on the change detection test, and were frequently unable to specify the change after having reported correctly that a change had taken place. Comparison participants, by contrast, frequently identified the change even when they failed to report the mismatch, an outcome that speaks to the sensitivity of the change specification measure. These results confirm past reports of hippocampal contributions to short-term retention of relational memory representations, and suggest that the role of the hippocampus in memory has more to do with relational memory requirements than the length of a retention interval. PMID:24478681

Yee, Lydia T S; Hannula, Deborah E; Tranel, Daniel; Cohen, Neal J

2014-01-01

11

Short-time Lyapunov exponent analysis  

NASA Technical Reports Server (NTRS)

A new technique for analyzing complicated fluid flows in numerical simulations has been successfully tested. The analysis uses short time Lyapunov exponent contributions and the associated Lyapunov perturbation fields. A direct simulation of the Taylor-Couette flow just past the onset of chaos demonstrated that this new technique marks important times during the system evolution and identifies the important flow features at those times. This new technique will now be applied to a 'minimal' turbulent channel.

Vastano, J. A.

1990-01-01

12

Very Short Time Lag of Sparking  

Microsoft Academic Search

Time lag of sparking in the very short time interval from 5.10-9 sec. to 115.10-9 sec. has been measured as a function of overvoltage and illumination using the electro-optical shutter with a constant illumination method. It was found that down to 10-9 sec. the time lags approached no lower limit if sufficiently high overvoltage was used. Variation of the intensity

Robert R. Wilson

1936-01-01

13

Universal short-time quantum critical dynamics in imaginary time  

NASA Astrophysics Data System (ADS)

We propose a scaling theory for the universal imaginary-time quantum critical dynamics for both short and long times. We discover that there exists a universal critical initial slip related to a small initial order parameter M0. In this stage, the order parameter M increases with the imaginary time ? as M ?M0?? with a universal initial-slip exponent ?. For the one-dimensional transverse-field Ising model, we estimate ? to be 0.373, which is markedly distinct from its classical counterpart. Apart from the local order parameter, we also show that the entanglement entropy exhibits universal behavior in the short-time region. As the critical exponents in the early stage and in equilibrium are identical, we apply the short-time dynamics method to determine quantum critical properties. The method is generally applicable in both the Landau-Ginzburg-Wilson paradigm and topological phase transitions.

Yin, Shuai; Mai, Peizhi; Zhong, Fan

2014-04-01

14

Short time cycles of purely quantum refrigerators.  

PubMed

Four stroke Otto refrigerator cycles with no classical analog are studied. Extremely short cycle times with respect to the internal timescale of the working medium characterize these refrigerators. Therefore, these cycles are termed sudden. The sudden cycles are characterized by the stable limit cycle, which is the invariant of the global cycle propagator. During their operation the states of the working medium possess significant coherence which is not erased in the equilibration segments due to the very short time allocated. This characteristic is reflected in a difference between the energy entropy and the Von Neumann entropy of the working medium. A classification scheme for sudden refrigerators is developed allowing simple approximations for the cooling power and coefficient of performance. PMID:23004710

Feldmann, Tova; Kosloff, Ronnie

2012-05-01

15

Short-time dynamics of nonextensive gluodynamics  

NASA Astrophysics Data System (ADS)

We introduce a new heat-bath thermalization algorithm to perform Monte Carlo simulations of gauge fields on the lattice in the nonextensive framework devised by Tsallis. This algorithm is employed to study the critical short-time relaxation dynamics of finite-temperature quenched Yang-Mills theory in that setup. Static and dynamic critical exponents computed around qTsallis ~ 1 regime are shown to approximately respect predictions from universality. Consequences of nonextensivity to the deconfinement phase transition are outlined.

Frigori, Rafael B.

2013-03-01

16

Short rise time intense electron beam generator  

DOEpatents

A generator for producing an intense relativisitc electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

Olson, C.L.

1984-03-16

17

Biogas from Macroalgae: is it time to revisit the idea?  

PubMed Central

The economic and environmental viability of dedicated terrestrial energy crops is in doubt. The production of large scale biomass (macroalgae) for biofuels in the marine environment was first tested in the late 1960’s. The culture attempts failed due to the engineering challenges of farming offshore. However the energy conversion via anaerobic digestion was successful as the biochemical composition of macroalgae makes it an ideal feedstock. The technology for the mass production of macroalgae has developed principally in China and Asia over the last 50 years to such a degree that it is now the single largest product of aquaculture. There has also been significant technology transfer and macroalgal cultivation is now well tried and tested in Europe and America. The inherent advantage of production of biofuel feedstock in the marine environment is that it does not compete with food production for land or fresh water. Here we revisit the idea of the large scale cultivation of macroalgae at sea for subsequent anaerobic digestion to produce biogas as a source of renewable energy, using a European case study as an example.

2012-01-01

18

Failure Prevention by Short Time Corrosion Tests  

SciTech Connect

Short time corrosion testing of perforated sheets and wire meshes fabricated from Type 304L stainless steel, Alloy 600 and C276 showed that 304L stainless steel perforated sheet should perform well as the material of construction for dissolver baskets. The baskets will be exposed to hot nitric acid solutions and are limited life components. The corrosion rates of the other alloys and of wire meshes were too high for useful extended service. Test results also indicated that corrosion of the dissolver should drop quickly during the dissolutions due to the inhibiting effects of the corrosion products produced by the dissolution processes.

MICKALONIS, JOHN

2005-05-01

19

Recognition of Short Time-Paired Activities  

NASA Astrophysics Data System (ADS)

We undertake numerous activities in our daily life and for some of those we forget to complete the action as originally intended. Significant aspects while performing most of these actions might be: “pairing of both hands simultaneously” and “short time consumption”. In this work an attempt has been made to recognize those kinds of Paired Activities (PAs), which are easy to forget, and to provide a method to remind about uncompleted PAs. To represent PAs, a study was done on opening and closing of various bottles. A model to define PAs, which simulated the paired behavior of both hands, is proposed, called “Paired Activity Model” (PAM). To recognize PAs using PAM, Paired Activity Recognition Algorithm (PARA) was implemented. Paired motion capturing was done by accelerometers, which were worn by subjects on the wrist areas of both hands. Individual and correlative behavior of both hands was used to recognize exact PA among other activities. Artificial Neural Network (ANN) algorithm was used for data categorization in PARA. ANN significantly outperformed the support vector machine algorithm in real time evaluations. In the user-independent case, PARA achieved recognition rates of 96% for only target PAs and 91% for target PAs undertaken amidst unrelated activities.

Chaminda, Hapugahage Thilak; Klyuev, Vitaly; Naruse, Keitaro; Osano, Minetada

20

``Sometimes'' and ``Not Never'' Revisited: On Branching Versus Linear Time  

Microsoft Academic Search

Temporal logic ([PR57], [PR67]) provides a formalism fordescribing the occurrence of events in time which is suitable forreasoning about concurrent programs (cf. [PN77]). In definingtemporal logic, there are two possible views regarding theunderlying nature of time. One is that time is linear: at eachmoment there is only one possible future. The other is that timehas a branching, tree-like nature: at

E. Allen Emerson; Joseph Y. Halpern

1983-01-01

21

On Lambda and Time Operators: the Inverse Intertwining Problem Revisited  

NASA Astrophysics Data System (ADS)

An exact theory of irreversibility was proposed by Misra, Prigogine and Courbage, based on non-unitary similarity transformations ? that intertwine reversible dynamics and irreversible ones. This would advocate the idea that irreversible behavior would originate at the microscopic level. Reversible evolution with an internal time operator have the intertwining property. Recently the inverse intertwining problem has been answered in the negative, that is, not every unitary evolution allowing such ?-transformation has an internal time. This work contributes new results in this direction.

Gómez-Cubillo, F.; Suchanecki, Z.; Villullas, S.

2011-07-01

22

Time delays for eleven gravitationally lensed quasars revisited  

NASA Astrophysics Data System (ADS)

Aims: We test the robustness of published time delays for 11 lensed quasars by using two techniques to measure time shifts in their light curves. Methods: We chose to use two fundamentally different techniques to determine time delays in gravitationally lensed quasars: a method based on fitting a numerical model and another one derived from the minimum dispersion method introduced by Pelt and collaborators. To analyse our sample in a homogeneous way and avoid bias caused by the choice of the method used, we apply both methods to 11 different lensed systems for which delays have been published: JVAS B0218+357, SBS 0909+523, RX J0911+0551, FBQS J0951+2635, HE 1104-1805, PG 1115+080, JVAS B1422+231, SBS 1520+530, CLASS B1600+434, CLASS B1608+656, and HE 2149-2745 Results: Time delays for three double lenses, JVAS B0218+357, HE 1104-1805, and CLASS B1600+434, as well as the quadruply lensed quasar CLASS B1608+656 are confirmed within the error bars. We correct the delay for SBS 1520+530. For PG 1115+080 and RX J0911+0551, the existence of a second solution on top of the published delay is revealed. The time delays in four systems, SBS 0909+523, FBQS J0951+2635, JVAS B1422+231, and HE 2149-2745 prove to be less reliable than previously claimed. Conclusions: If we wish to derive an estimate of H0 based on time delays in gravitationally lensed quasars, we need to obtain more robust light curves for most of these systems in order to achieve a higher accuracy and robustness on the time delays.

Eulaers, E.; Magain, P.

2011-12-01

23

Analysis of fMRI Time-Series Revisited  

Microsoft Academic Search

This paper presents a general approach to the analysis of functional MRI time-series from one or more subjects. The approach is predicated on an extension of the general linear model that allows for correlations between error terms due to physiological noise or correlations that ensue after temporal smoothing. This extension uses the effective degrees of freedom associated with the error

K. J. Friston; A. P. Holmes; J. B. Poline; P. J. Grasby; S. C. R. Williams; R. S. J. Frackowiak; R. Turner

1995-01-01

24

Through the mists of time: Sushrutha, an enigma revisited  

PubMed Central

Sushrutha had been viewed in textbooks of plastic surgery as belonging to the caste of potters who performed surgery in India. We have examined the available source documents and other references to the technology of the period to examine this assertion and are convinced that there is no evidence to support this. The period, technology and geographic references in Sushrutha Samhitha are correlated with settled positions on these to arrive at an understanding of the time and knowledge which is described. Source of erroneous interpretation of Sushrutha as a potter is also examined and clarified.

Puthumana, Philip Philip

2009-01-01

25

Revisiting the Central Dogma One Molecule at a Time  

PubMed Central

The faithful relay and timely expression of genetic information depend on specialized molecular machines, many of which function as nucleic acid translocases. The emergence over the last decade of single-molecule fluorescence detection and manipulation techniques with nm and Å resolution, and their application to the study of nucleic acid translocases are painting an increasingly sharp picture of the inner workings of these machines, the dynamics and coordination of their moving parts, their thermodynamic efficiency, and the nature of their transient intermediates. Here we present an overview of the main results arrived at by the application of single-molecule methods to the study of the main machines of the central dogma.

Bustamante, Carlos; Cheng, Wei; Meija, Yara

2011-01-01

26

Nuclear Winter Revisited: can it Make a Difference This Time?  

NASA Astrophysics Data System (ADS)

Some 23 years ago, in the middle of a Cold War and the threat of a strategic nuclear weapons exchange between NATO and the Warsaw Pact nations, atmospheric scientists pointed out that the well-anticipated side effects of a large-scale nuclear war ozone depletion, radioactive contamination and some climatic effects had massively underestimated the more likely implications: massive fires, severe dimming and cooling beneath circulating smoke clouds, disruption to agriculture in non-combatant nations, severe loss of imports of food to already-food-deficient regions and major alterations to atmospheric circulation. While the specific consequences were dependent on both scenarios of weapons use and injections and removals of smoke and dust and other chemicals into the atmosphere, it was clear that this would be despite passionately argued uncertainties a large major additional effect. As further investigations of smoke removal, patchy transport, etc., were pursued, the basic concerns remained, but the magnitude calculated with one-dimensional models diminished creating an unfortunate media debate over nuclear winter vs. nuclear autumn. Of course, one can't grow summer crops in any autumn natural or nuclear but that concern often got lost in the contentious political debate. Of course, it was pointed out that anyone who required knowing the additional environmental consequences of a major nuclear exchange to be finally deterred was already so far from the reality of the direct effects of the blasts that they might never see the concerns. But for non-combatants, it was a major awakening of their inability to escape severe consequences of the troubles of others, even if they were bystanders in the east-west conflicts. Two decades later, things have radically changed: the prospect of a massive strategic nuclear exchange is greatly diminished good news but the possibility of limited regional exchanges or terrorist incidents is widely believed to have greatly increased bad news. Therefore, the re- examination in this AGU session of the entire subject of environmental and social after-effects of any nuclear weapons use is, unfortunately, once again timely. Hopefully it will convince anyone not already convinced based on conventional damages from nuclear weapons use of the urgent need to abate proliferation and monitor and control access to and potential capabilities of those who might contemplate using such weapons for some Strangelove-like strategic or ideological objective. The extent to which a scientific re-examination of the broader horrendous implications of any scale of use of nuclear weapons will deter those contemplating their use is questionable. However, it seems likely such research would increase the resolve of the large number of countries and institutions already pressing to prevent nuclear weapons use.

Schneider, S.

2006-12-01

27

The Demise of Short-Term Memory Revisited: Empirical and Computational Investigations of Recency Effects  

Microsoft Academic Search

In the single-store model of memory, the enhanced recall for the last items in a free-recall task (i.e., the recency effect) is understood to reflect a general property of memory rather than a separate short-term store. This interpretation is supported by the finding of a long-term recency effect under conditions that eliminate the contribution from the short-term store. In this

Eddy J. Davelaar; Yonatan Goshen-Gottstein; Amir Ashkenazi; Henk J. Haarmann; Marius Usher

2005-01-01

28

Short-term travel time prediction  

Microsoft Academic Search

Effective prediction of travel times is central to many advanced traveler information and transportation management systems. In this paper we propose a method to predict freeway travel times using a linear model in which the coefficients vary as smooth functions of the departure time. The method is straightforward to implement, computationally efficient and applicable to widely available freeway sensor data.We

Xiaoyan Zhang; John A. Rice

2003-01-01

29

The Demise of Short-Term Memory Revisited: Empirical and Computational Investigations of Recency Effects  

ERIC Educational Resources Information Center

In the single-store model of memory, the enhanced recall for the last items in a free-recall task (i.e., the recency effect) is understood to reflect a general property of memory rather than a separate short-term store. This interpretation is supported by the finding of a long-term recency effect under conditions that eliminate the contribution…

Davelaar,Eddy J.; Goshen-Gottstein, Yonatan; Ashkenazi, Amir; Haarmann, Henk J.; Usher, Marius

2005-01-01

30

Controlled short residence time coal liquefaction process  

DOEpatents

Normally solid dissolved coal product and a distillate liquid product are produced by continuously passing a feed slurry comprising raw feed coal and a recycle solvent oil and/or slurry together with hydrogen to a preheating-reaction zone (26, alone, or 26 together with 42), the hydrogen pressure in the preheating-reaction zone being at least 1500 psig (105 kg/cm.sup.2), reacting the slurry in the preheating-reaction zone (26, or 26 with 42) at a temperature in the range of between about 455.degree. and about 500.degree. C. to dissolve the coal to form normally liquid coal and normally solid dissolved coal. A total slurry residence time is maintained in the reaction zone ranging from a finite value from about 0 to about 0.2 hour, and reaction effluent is continuously and directly contacted with a quenching fluid (40, 68) to substantially immediately reduce the temperature of the reaction effluent to below 425.degree. C. to substantially inhibit polymerization so that the yield of insoluble organic matter comprises less than 9 weight percent of said feed coal on a moisture-free basis. The reaction is performed under conditions of temperature, hydrogen pressure and residence time such that the quantity of distillate liquid boiling within the range C.sub.5 -455.degree. C. is an amount at least equal to that obtainable by performing the process under the same conditions except for a longer total slurry residence time, e.g., 0.3 hour. Solvent boiling range liquid is separated from the reaction effluent and recycled as process solvent.

Anderson, Raymond P. (Overland Park, KS); Schmalzer, David K. (Englewood, CO); Wright, Charles H. (Overland Park, KS)

1982-05-04

31

Potential barrier classification by short-time measurement  

SciTech Connect

We investigate the short-time dynamics of a delta-function potential barrier on an initially confined wave packet. There are mainly two conclusions: (A) At short times the probability density of the first particles that passed through the barrier is unaffected by it. (B) When the barrier is absorptive (i.e., its potential is imaginary) it affects the transmitted wave function at shorter times than a real potential barrier. Therefore, it is possible to distinguish between an imaginary and a real potential barrier by measuring its effect at short times only on the transmitting wave function.

Granot, Er'el; Marchewka, Avi [Department of Electrical and Electronics Engineering, College of Judea and Samaria, Ariel (Israel); Kibbutzim College of Education, Ramat-Aviv, 104 Namir Road 69978 Tel-Aviv (Israel)

2006-03-15

32

The short-period low-mass binary system CC Com revisited  

Microsoft Academic Search

In this study we determined precise orbital and physical parameters of the very short-period low-mass contact binary system CC Com. The parameters are obtained by analysis of new CCD data combined with archival spectroscopic data. The physical parameters of the cool and hot components are derived as M_{c} = 0.717(14) M&sun;, M_{h} = 0.378(8) M&sun;, R_{c} = 0.708(12) R&sun;, R_{h}

O. Köse; B. Kalomeni; V. Keskin; B. Ulas; K. Yakut

2011-01-01

33

Short time-series microarray analysis: Methods and challenges  

PubMed Central

The detection and analysis of steady-state gene expression has become routine. Time-series microarrays are of growing interest to systems biologists for deciphering the dynamic nature and complex regulation of biosystems. Most temporal microarray data only contain a limited number of time points, giving rise to short-time-series data, which imposes challenges for traditional methods of extracting meaningful information. To obtain useful information from the wealth of short-time series data requires addressing the problems that arise due to limited sampling. Current efforts have shown promise in improving the analysis of short time-series microarray data, although challenges remain. This commentary addresses recent advances in methods for short-time series analysis including simplification-based approaches and the integration of multi-source information. Nevertheless, further studies and development of computational methods are needed to provide practical solutions to fully exploit the potential of this data.

Wang, Xuewei; Wu, Ming; Li, Zheng; Chan, Christina

2008-01-01

34

Nonequilibrium Physics at Short Time Scales: Formation of Correlations  

Microsoft Academic Search

It is a happy situation when similar concepts and theoretical techniques can be applied to widely different physical systems because of a deep similarity in the situations being studied. The book illustrates this well; it focuses on the description of correlations in quantum systems out of equilibrium at very short time scales, prompted by experiments with short laser pulses in

L Peliti

2005-01-01

35

Hydromagnetic interpretation of short time scale structures in solar flares  

Microsoft Academic Search

Hydromagnetic interpretation of the solar flare short time scale structure indicated in microwave and hard X-ray emission during the impulsive phase is presented. The main assumption is that the plasma ejection from the current sheet may be considered as a forced convection by an isolated source. From this point of view some analogies with small scale short lasting hydrodynamic and

V. M. Dermendjiev

1986-01-01

36

A Revisited Tsypkin Criterion for Discrete-Time Nonlinear Lur’e Systems with Monotonic Sector-Restrictions  

Microsoft Academic Search

This paper revisits a well-known Tsypkin criterion for stability analysis of discrete-time nonlinear Lur’e systems. When nonlinearities are monotonic and sector restricted by [0,??], where ?? is positive definite, it is shown by Kapila and Haddad that the system is absolutely stable if a function G0(z)=??-1+{I+(1?z-1)K+}G(z) is strictly positive real, where K+ is nonnegative diagonal and G(z) represents a transfer

SANG WOO KIM

1998-01-01

37

Short-term and long-term stability of surgically assisted rapid palatal expansion revisited  

PubMed Central

Introduction The purpose of this article is to present further longitudinal data for short-term and long-term stability, following up our previous article in the surgery literature with a larger sample and 2 years of stability data. Methods Data from 38 patients enrolled in this prospective study were collected before treatment, at maximum expansion, at removal of the expander 6 months later, before any second surgical phase, at the end of orthodontic treatment, and at the 2-year follow-up, by using posteroanterior cephalograms and dental casts. Results With surgically assisted rapid palatal expansion (SARPE), the mean maximum expansion at the first molar was 7.60 ± 1.57 mm, and the mean relapse was 1.83 ± 1.83 mm (24%). Modest relapse after completion of treatment was not statistically significant for all teeth except for the maxillary first molar (0.99 ± 1.1 mm). A significant relationship (P <0.0001) was observed between the amount of relapse after SARPE and the posttreatment observation. At maximum, a skeletal expansion of 3.58 ± 1.63 mm was obtained, and this was stable. Conclusions Skeletal changes with SARPE were modest but stable. Relapse in dental expansion was almost totally attributed to lingual movement of the posterior teeth; 64% of the patients had more than 2 mm of dental changes. Phase 2 surgery did not affect dental relapse.

Chamberland, Sylvain; Proffit, William R.

2014-01-01

38

Time relaxation of ac susceptibility on very short time scales  

Microsoft Academic Search

We present an experimental method enabling measurements of time dependence of ac susceptibility down to 1 ms after a steplike change of the applied dc magnetic field. An analog-digital converter has been used to collect the transient of the current, signaling the change of the dc magnetic field. The time window for investigation of magnetic time relaxation phenomena, as studied

Ivica Zivkovic; Ðuro Drobac; Mladen Prester

2005-01-01

39

Waveform for Short-Dwell-Time Meteorological Doppler Radars.  

National Technical Information Service (NTIS)

A modulation waveform for meteorological Doppler radars that obtain estimates of radar reflectivity, mean velocity, and Doppler width with very short dwell time is described. The transmitted signal is a sequence of three identical chirp pulses; signal par...

R. G. Strauch

1987-01-01

40

Short-Time Power Spectra: Estimation and Acoustical Applications.  

National Technical Information Service (NTIS)

The study deals with the theoretical background and practical acoustical applications of the short-time FFT frequency analysis. The fundamental concept of the instantaneous spectrum is reviewed. Its practical estimation by the lagged window FFT and the st...

T. Lahti

1983-01-01

41

Short-time scaling of variable ordering of OBDDs  

Microsoft Academic Search

A short-time scaling criterion of variable ordering of OBDDs is proposed. By this criterion it is easy and fast to determine\\u000a which one is better when several variable orders are given, especially when they differ 10% or more in resulted BDD size from\\u000a each other. An adaptive variable order selection method, based on the short-time scaling criterion, is also presented.

Wangning Long; Yinghua Min; Shiyuan Yang; Shibai Tong

1997-01-01

42

Measurement of hyperpolarized gas diffusion at very short time scales  

Microsoft Academic Search

We present a new pulse sequence for measuring very-short-time-scale restricted diffusion of hyperpolarized noble gases. The pulse sequence is based on concatenating a large number of bipolar diffusion-sensitizing gradients to increase the diffusion attenuation of the MR signal while maintaining a fundamentally short diffusion time. However, it differs in several respects from existing methods that use oscillating diffusion gradients for

Michael Carl; G. Wilson Miller; John P. Mugler; Scott Rohrbaugh; William A. Tobias; Gordon D. Cates

2007-01-01

43

Short-term Forecasting of Travel Time and Reliability  

Microsoft Academic Search

In this paper, a traffic flow simulator (TFS) is presented to forecast the short-term travel time and reliability that can be served as a predicted travel time database for the Hong Kong transport information system or advanced traveler information system. The forecasted travel time information is useful for the pre-trip planning of the drivers. The drivers can decide their departure

William Lam; K. S. Chan

2004-01-01

44

Orphan drugs for rare diseases: is it time to revisit their special market access status?  

PubMed

Orphan drugs are intended for diseases with a very low prevalence, and many countries have implemented legislation to support market access of orphan drugs. We argue that it is time to revisit the special market access status of orphan drugs. Indeed, evidence suggests that there is no societal preference for treating rare diseases. Although society appears to assign a greater value to severity of disease, this criterion is equally relevant to many common diseases. Furthermore, the criterion of equity in access to treatment, which underpins orphan drug legislation, puts more value on health improvement in rare diseases than in common diseases and implies that population health is not maximized. Finally, incentives for the development, pricing and reimbursement of orphan drugs have created market failures, including monopolistic prices and the artificial creation of rare diseases. We argue that, instead of awarding special market access status to orphan drugs, there is scope to optimize research and development (R&D) of orphan drugs and to control prices of orphan drugs by means of, for example, patent auctions, advance purchase commitments, pay-as-you-go schemes and dose-modification studies. Governments should consider carefully the right incentive strategy for R&D of orphan drugs in rare diseases. PMID:22747423

Simoens, Steven; Cassiman, David; Dooms, Marc; Picavet, Eline

2012-07-30

45

Short time-scale structural variation in 3C 273  

Microsoft Academic Search

The results of VLBI observations at 22 GHz and 43 GHz of the quasar 3C 273 are presented Hybrid maps and modelfitting were made to look for any short time-scale structural variation in the jet. The jet structure did not show dramatic changes during the 42 days in which 3C 273 was observed 5 times at almost 10 day intervals.

F. Mantovani; C. Valerio; W. Junor; I. McHardy

1999-01-01

46

Time-dependent pair distribution function: The constant acceleration approximation revisited  

NASA Astrophysics Data System (ADS)

The constant-acceleration approximation for the time-dependent pair distribution function as introduced by Bloom and Oppenheim is critically examined. The previously noted inconsistencies for the initial behaviour of the correlation functions are eliminated by a proper treatment of the short time dynamics.

Balucani, U.; Vallauri, R.

1980-03-01

47

Short time-series microarray analysis: Methods and challenges  

Microsoft Academic Search

The detection and analysis of steady-state gene expression has become routine. Time-series microarrays are of growing interest to systems biologists for deciphering the dynamic nature and complex regulation of biosystems. Most temporal microarray data only contain a limited number of time points, giving rise to short-time-series data, which imposes challenges for traditional methods of extracting meaningful information. To obtain useful

Xuewei Wang; Ming Wu; Zheng Li; Christina Chan

2008-01-01

48

Continuous time random walks revisited: first passage time and spatial distributions  

Microsoft Academic Search

We investigate continuous time random walk (CTRW) theory, which often assumes an algebraic decay for the single transition time probability density function (pdf) ?(t)?t?1?? for large times t. In this form, ? is a constant (0time\\/distance distributions has been ubiquitous in the development of different

Gennady Margolin; Brian Berkowitz

2004-01-01

49

Speech processing based on short-time Fourier analysis  

SciTech Connect

Short-time Fourier analysis (STFA) is a mathematical technique that represents nonstationary signals, such as speech, music, and seismic signals in terms of time-varying spectra. This representation provides a formalism for such intuitive notions as time-varying frequency components and pitch contours. Consequently, STFA is useful for speech analysis and speech processing. This paper shows that STFA provides a convenient technique for estimating and modifying certain perceptual parameters of speech. As an example of an application of STFA of speech, the problem of time-compression or expansion of speech, while preserving pitch and time-varying frequency content is presented.

Portnoff, M.R.

1981-06-02

50

Signal estimation from modified short-time Fourier transform  

Microsoft Academic Search

In this paper, we present an algorithm to estimate a signal from its modified short-time Fourier transform (STFT). This algorithm is computationally simple and is obtained by minimizing the mean squared error between the STFT of the estimated signal and the modified STFT. Using this algorithm, we also develop an iterative algorithm to estimate a signal from its modified STFT

DANIEL W. GRIFFIN; JAE S. LIM

1984-01-01

51

High-temperature-short-time thermal quarantine methods  

Microsoft Academic Search

In this paper, kinetic models are discussed with respect to their uses in describing the intrinsic thermal mortality of insect pests. A unique heating block system was used to obtain kinetic information for the thermal mortality of codling moth larvae. The kinetic data demonstrated the possibility to develop high-temperature-short-time thermal treatments to control codling moth and reduce thermal impact on

J. Tang; J. N. Ikediala; S. Wang; J. D. Hansen; R. P. Cavalieri

2000-01-01

52

Instantaneous scale and the short-time scale transform  

Microsoft Academic Search

The concept of instantaneous scale, ci, is developed and it is shown that it is given by ci=tØ'(t) where Ø'( t) is the derivative of the phase of the signal. Formulas for average scale, scale bandwidth, and scale group delay are obtained. The scale transform, the short time scale transform, the analytic scale signal, and other related concepts are defined

LEON COHEN

1992-01-01

53

A Platform for Processing Expression of Short Time Series (PESTS)  

PubMed Central

Background Time course microarray profiles examine the expression of genes over a time domain. They are necessary in order to determine the complete set of genes that are dynamically expressed under given conditions, and to determine the interaction between these genes. Because of cost and resource issues, most time series datasets contain less than 9 points and there are few tools available geared towards the analysis of this type of data. Results To this end, we introduce a platform for Processing Expression of Short Time Series (PESTS). It was designed with a focus on usability and interpretability of analyses for the researcher. As such, it implements several standard techniques for comparability as well as visualization functions. However, it is designed specifically for the unique methods we have developed for significance analysis, multiple test correction and clustering of short time series data. The central tenet of these methods is the use of biologically relevant features for analysis. Features summarize short gene expression profiles, inherently incorporate dependence across time, and allow for both full description of the examined curve and missing data points. Conclusions PESTS is fully generalizable to other types of time series analyses. PESTS implements novel methods as well as several standard techniques for comparability and visualization functions. These features and functionality make PESTS a valuable resource for a researcher's toolkit. PESTS is available to download for free to academic and non-profit users at http://www.mailman.columbia.edu/academic-departments/biostatistics/research-service/software-development.

2011-01-01

54

Adaptive short-time analysis-synthesis for speech enhancement  

Microsoft Academic Search

ABSTRACT In this paper we present a new adaptive short-time Fourier analysis- synthesis scheme,and demonstrate,its efficacy in speech enhance- ment. While a number,of adaptive analyses have previously been proposed to overcome the limitations of fixed-resolution schemes, we propose here a modified overlap-add procedure that enables effi- cient resynthesis. Our adaptation scheme,extends earlier work using local measures of time-frequency concentration, and

Daniel Rudoy; Prabahan Basu; Thomas F. Quatieri; Bob Dunn; Patrick J. Wolfe

2008-01-01

55

Short time scale monitoring of SiO sources  

Microsoft Academic Search

We present the results of a short time scale monitoring of SiO maser emission (v=1 J=1-0 transition) in four known strong sources. These sources were monitored nightly for a period of about a month. The aim of these observations is to investigate the possible presence of variations in the maser lines on time scales of a few days to weeks,

F. P. Pijpers; J. R. Pardo; V. Bujarrabal

1994-01-01

56

Short-time scale variability in some Be stars  

Microsoft Academic Search

The short-time scale spectroscopic variability of some Be stars has been investigated with an optical fiber spectrograph and a CCD camera. Findings on a time-scale of hours and days include: (1) weak changes in the H-alpha emission line profile of gamma Cas; (2) changes in the structure and the intensity of the H-alpha emission line core and sometimes in the

H. Hubert; B. Dagostinoz; A. M. Hubert; M. Floquet

1987-01-01

57

Non-24-Hour Disorder in Blind Individuals Revisited: Variability and the Influence of Environmental Time Cues  

PubMed Central

Study Objectives: To assess the interindividual and intraindividual variability in the circadian rhythms of blind individuals with non-24-h disorder and to quantify the influence of environmental time cues in blind subjects lacking entrainment (non-24-h individuals or N-24s). Design: An observational study of 21 N-24s (11 females and 10 males, age 9-78 years) who kept a sleep/wake schedule of their choosing. Circadian phase was determined using the melatonin onset (MO) from plasma or saliva samples that were collected every 2 weeks. Melatonin concentrations were measured by radioimmunoassay. A total of 469 MO assessments were conducted over 5,536 days of study. The rate of drift of circadian phase was calculated using a series of MOs (total number of hours the MO drifted divided by the total number of days studied). Stability of the rest/activity rhythm was calculated using chi-squared periodogram analysis of wrist actigraphy data in 19 subjects. Setting: Academic medical center. Participants: Paid volunteers. Interventions: N/A. Measurements and Results: Subjects lacked entrainment such that circadian phase drifted an average (± standard deviation) of 0.39 ± 0.29 h later per day; however, there was notable intersubject and intrasubject variability in the rate of drift including relative coordination and periods of transient entrainment during which there was little to no drift in the circadian phase. A regular, reproducible, and significant oscillation in the rate of drift was detected in 14 of the 21 subjects. A significant non-24-h rest/activity rhythm was detected in 18 of 19 subjects. There was a strong correlation (r = 0.793, P = 0.0001) between the non-24-h rest/activity rhythm and the rate of drift of the circadian phase. Conclusions: Most N-24s are influenced by unidentified environmental time cues and the non-entrained biological clock in such N-24s is reflected in their rest/activity rhythms. These findings may have diagnostic and treatment implications: this disorder might be diagnosed with actigraphy alone, relative coordination and transient entrainment may result in misdiagnosis and responsiveness to environmental time cues may influence treatment success with oral melatonin. Citation: Emens JS; Laurie AL; Songer JB; Lewy AJ. Non-24-hour disorder in blind individuals revisited: variability and the influence of environmental time cues. SLEEP 2013;36(7):1091-1100.

Emens, Jonathan S.; Laurie, Amber L.; Songer, Jeannie B.; Lewy, Alfred J.

2013-01-01

58

The time course of photoinactivation of photosystem II in leaves revisited.  

PubMed

Since photosystem II (PS II) performs the demanding function of water oxidation using light energy, it is susceptible to photoinactivation during photosynthesis. The time course of photoinactivation of PS II yields useful information about the process. Depending on how PS II function is assayed, however, the time course seems to differ. Here, we revisit this problem by using two additional assays: (1) the quantum yield of oxygen evolution in limiting, continuous light and (2) the flash-induced cumulative delivery of PS II electrons to the oxidized primary donor (P700(+)) in PS I measured as a 'P700 kinetics area'. The P700 kinetics area is based on the fact that the two photosystems function in series: when P700 is completely photo-oxidized by a flash added to continuous far-red light, electrons delivered from PS II to PS I by the flash tend to re-reduce P700(+) transiently to an extent depending on the PS II functionality, while the far-red light photo-oxidizes P700 back to the steady-state concentration. The quantum yield of oxygen evolution in limiting, continuous light indeed decreased in a way that deviated from a single-negative exponential. However, measurement of the quantum yield of oxygen in limiting light may be complicated by changes in mitochondrial respiration between darkness and limiting light. Similarly, an assay based on chlorophyll fluorescence may be complicated by the varying depth in leaf tissue from which the signal is detected after progressive photoinactivation of PS II. On the other hand, the P700 kinetics area appears to be a reasonable assay, which is a measure of functional PS II in the whole leaf tissue and independent of changes in mitochondrial respiration. The P700 kinetics area decreased in a single-negative exponential fashion during progressive photoinactivation of PS II in a number of plant species, at least at functional PS II contents ?6 % of the initial value, in agreement with the conclusion of Sarvikas et al. (Photosynth Res 103:7-17, 2010). That is, the single-negative-exponential time course does not provide evidence for photoprotection of functional PS II complexes by photoinactivated, connected neighbours. PMID:22644475

Kou, Jiancun; Oguchi, Riichi; Fan, Da-Yong; Chow, Wah Soon

2012-09-01

59

Statistical Detection of Short Periodic Gene Expression Time Series Profiles  

NASA Astrophysics Data System (ADS)

Many cellular processes exhibit periodic behaviors. Hence, one of the important tasks in gene expression data analysis is to detect subset of genes that exhibit cyclicity or periodicity in their gene expression time series profiles. Unfortunately, gene expression time series profiles are usually of very short length and highly contaminated with noise. This makes detection of periodic profiles a very difficult problem. Recently, a hypothesis testing method based on the Fisher g-statistic with correction for multiple testing has been proposed to detect periodic gene expression profiles. However, it was observed that the test is not reliable if the signal length is too short. In this paper, we performed extensive simulation study to investigate the statistical power of the test as a function of signal length, SNR, and the false discovery rate. We found that the number of periodic profiles can be severely underestimated for short length signal. The findings indicated that caution needs to be exercised when interpreting the test result for very short length signals.

Liew, Alan Wee-Chung; Law, N. F.; Yan, Hong

2007-11-01

60

The Galaxy Viewed at Very Short Time-Scales  

NASA Astrophysics Data System (ADS)

We present high time-resolution astronomical observations recorded with the Berkeley Visible Image Tube (BVIT) photon counting detector mounted on the 10m South African Large Telescope (SALT). Relative B and V-band photometric fluxes were obtained as a function of time for targets that included Polar-type cataclysmic variables (UZ For, OY Car, V1033Cen), low-mass X-ray binaries (GX 339-4, UY Vol), pulsars (PSR 0540-69), dMe flare stars (CN Leo) and active galactic nucleii (Mkn 618). These observations, which were recorded during several nights of engineering time at SALT in early 2009, indicate that there are many types of astrophysical processes operating over very short time-scales in a wide variety of astronomical objects. The high-time resolution capability of the BVIT detector allowed emission features occurring on time-scales as short as tens of milli-seconds to be revealed. In particular, we have measured the optical period of the PSR 0540-69 pulsar to be 0.05065018808s and we have also detected several quasi-periodic oscillations operating on time-scales of < 0.5 s in the emitted flux from the X-ray transient source, GX 339-4. These preliminary data indicate that the new field of high time-resolution astronomy is providing important new insights into the transient nature of the Universe.

Radnia, Navid; Siegmund, O.; Welsh, B.; Mcphate, J.; Rogers, D.; Charles, P.; Buckley, D.

2010-01-01

61

Predator-prey interactions, resource depression and patch revisitation  

USGS Publications Warehouse

Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short 'recovery' times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

Erwin, R.M.

1989-01-01

62

Parameters of spike trains observed in a short time window.  

PubMed

We study the estimation of statistical moments of interspike intervals based on observation of spike counts in many independent short time windows. This scenario corresponds to the situation in which a target neuron occurs. It receives information from many neurons and has to respond within a short time interval. The precision of the estimation procedures is examined. As the model for neuronal activity, two examples of stationary point processes are considered: renewal process and doubly stochastic Poisson process. Both moment and maximum likelihood estimators are investigated. Not only the mean but also the coefficient of variation is estimated. In accordance with our expectations, numerical studies confirm that the estimation of mean interspike interval is more reliable than the estimation of coefficient of variation. The error of estimation increases with increasing mean interspike interval, which is equivalent to decreasing the size of window (less events are observed in a window) and with decreasing the number of neurons (lower number of windows). PMID:18194105

Pawlas, Zbynek; Klebanov, Lev B; Prokop, Martin; Lansky, Petr

2008-05-01

63

Quartz Rheology and Short-time-scale Crustal Instabilities  

Microsoft Academic Search

We present numerical results of thermal-mechanical feedback in crustal quartz rheology and contrast this behavior to the vastly\\u000a different character of an olivine mantle. In the numerical experiments quartz is found to have a very strong tendency for\\u000a short-time-scale instabilities, while our numerical experiments show that olivine has a decisive tendency for a stable thermally\\u000a lubricated slip. At the same

Klaus Regenauer-Lieb; David A. Yuen

2006-01-01

64

Short-time-scale features of the Earth's polar motion  

Microsoft Academic Search

The fundamental astrometric problem of high-accuracy interpolation and forecasting of the Earth's polar motion on short time scales from 1-2 to 10-30 days is studied. Hierarchies of interval length and parameter accuracy are established using appropriate models for the process. Filtering algorithms are adjusted using a weighted least squares fit of measurements of the International Earth Rotation Service (IERS). Best-fit

L. D. Akulenko; Yu. G. Markov; V. V. Perepelkin; L. V. Rykhlova

2009-01-01

65

Cyclization of Rouse Chains at Long and Short Time Scales  

Microsoft Academic Search

We have investigated cyclization of a Rouse chain at long and short times by a Langevin dynamics simulation method. We measure S(t), the fraction of non-reacted chains, for chains lengths ranging from Z=5 to Z=800. Comparison is made with the closure approximations of Wilemski and Fixman and Doi and the renormalization group (RG) arguments of Friedman and O'Shaughnessy. The ratio

Chuck Yeung; Barry Friedman

2005-01-01

66

Short time-scale variability in bright Seyfert galaxies  

Microsoft Academic Search

High-quality, long-slit CCD spectroscopic data were obtained to search for short time-scale (hour-day) variability in a sample of five Seyfert galaxies. The equivalent widths of all of the emission lines and the relative intensities of the Balmer lines were measured for each galaxy. No significant profile or flux variations were observed for any galaxy within errors, except for NGC 4151.

E. Xanthopoulos; M. M. De Robertis

1991-01-01

67

Quartz Rheology and Short-time-scale Crustal Instabilities  

Microsoft Academic Search

We present numerical results of thermal-mechanical feedback in crustal quartz rheology and contrast this behavior to the vastly\\u000a different character of an olivine mantle. In the numerical experiments quartz is found to have a very strong tendency for\\u000a short-time-scale instabilities, while our numerical experiments show that olivine has a decisive tendency for a stable thermally\\u000a lubricated slip. At the same

Klaus Regenauer-Lieb; David A. Yuen

68

Erratum: Short-time scaling behavior of growing interfaces  

Microsoft Academic Search

The short-time evolution of a growing interface is studied analytically and numerically for the Kadar-Parisi-Zhang (KPZ) universality class. The scaling behavior of response and correlation functions is reminiscent of the ``initial slip'' behavior found in purely dissipative critical relaxation (model A). Unlike model A the initial slip exponent for the KPZ equation can be expressed by the dynamical exponent z.

Michael Krech

1997-01-01

69

Variations in solar Lyman alpha irradiance on short time scales  

Microsoft Academic Search

Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME\\/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It

J. M. Pap

1992-01-01

70

Short-time scaling behavior of growing interfaces  

Microsoft Academic Search

The short-time evolution of a growing interface is studied within the framework of the dynamic renormalization-group approach for the Kadar-Parisi-Zhang (KPZ) equation and for an idealized continuum model of molecular-beam epitaxy. The scaling behavior of response and correlation functions is reminiscent of the ``initial slip'' behavior found in purely dissipative critical relaxation (model A) and critical relaxation with conserved order

Michael Krech; Fachbereich Physik

1997-01-01

71

Short time scale monitoring of SiO sources  

Microsoft Academic Search

We present the results of a short time scale monitoring of SiO maser emission\\u000a(v=1 J=1-0 transition) in four known strong sources. These sources were\\u000amonitored nightly for a period of about a month. The aim of these observations\\u000ais to investigate the possible presence of variations in the maser lines on\\u000atime scales of a few days to weeks,

F. P. Pijpers; J. R. Pardo; V. Bujarrabal

1994-01-01

72

Measurement of hyperpolarized gas diffusion at very short time scales  

PubMed Central

We present a new pulse sequence for measuring very-short-time-scale restricted diffusion of hyperpolarized noble gases. The pulse sequence is based on concatenating a large number of bipolar diffusion-sensitizing gradients to increase the diffusion attenuation of the MR signal while maintaining a fundamentally short diffusion time. However, it differs in several respects from existing methods that use oscillating diffusion gradients for this purpose. First, a wait time is inserted between neighboring pairs of gradient pulses; second, consecutive pulse pairs may be applied along orthogonal axes; and finally, the diffusion-attenuated signal is not simply read out at the end of the gradient train but is periodically sampled during the wait times between neighboring pulse pairs. The first two features minimize systematic differences between the measured (apparent) diffusion coefficient and the actual time-dependent diffusivity, while the third feature optimizes the use of the available MR signal to improve the precision of the diffusivity measurement in the face of noise. The benefits of this technique are demonstrated using theoretical calculations, Monte-Carlo simulations of gas diffusion in simple geometries, and experimental phantom measurements in a glass sphere containing hyperpolarized 3He gas. The advantages over the conventional single-bipolar approach were found to increase with decreasing diffusion time, and thus represent a significant step toward making accurate surface-to-volume measurements in the lung airspaces.

Carl, Michael; Wilson Miller, G.; Mugler, John P.; Rohrbaugh, Scott; Tobias, William A.; Cates, Gordon D.

2007-01-01

73

Measurement of hyperpolarized gas diffusion at very short time scales  

NASA Astrophysics Data System (ADS)

We present a new pulse sequence for measuring very-short-time-scale restricted diffusion of hyperpolarized noble gases. The pulse sequence is based on concatenating a large number of bipolar diffusion-sensitizing gradients to increase the diffusion attenuation of the MR signal while maintaining a fundamentally short diffusion time. However, it differs in several respects from existing methods that use oscillating diffusion gradients for this purpose. First, a wait time is inserted between neighboring pairs of gradient pulses; second, consecutive pulse pairs may be applied along orthogonal axes; and finally, the diffusion-attenuated signal is not simply read out at the end of the gradient train but is periodically sampled during the wait times between neighboring pulse pairs. The first two features minimize systematic differences between the measured (apparent) diffusion coefficient and the actual time-dependent diffusivity, while the third feature optimizes the use of the available MR signal to improve the precision of the diffusivity measurement in the face of noise. The benefits of this technique are demonstrated using theoretical calculations, Monte-Carlo simulations of gas diffusion in simple geometries, and experimental phantom measurements in a glass sphere containing hyperpolarized 3He gas. The advantages over the conventional single-bipolar approach were found to increase with decreasing diffusion time, and thus represent a significant step toward making accurate surface-to-volume measurements in the lung airspaces.

Carl, Michael; Wilson Miller, G.; Mugler, John P.; Rohrbaugh, Scott; Tobias, William A.; Cates, Gordon D.

2007-12-01

74

Short-time scale behavior modeling within long-time scale fuel cycle evaluations  

SciTech Connect

Typically, short-time and long-time scales in nuclear energy system behavior are accounted for with entirely separate models. However, long-term changes in system characteristics do affect short-term transients through material variations. This paper presents an approach to consistently account for short-time scales within a nuclear system lifespan. The reported findings and developments are of significant importance for small modular reactors and other nuclear energy systems operating in autonomous modes. It is necessary to simulate the short time-scale kinetic behavior of the reactor as well as the long time-scale dynamics that occur with fuel burnup. The former is modeled using the point kinetics equations, while the latter is modeled by the Bateman equations. (authors)

Johnson, M.; Tsvetkov, P. [Dept. of Nuclear Engineering, Texas A and M Univ., 3133 TAMU, College Station, TX 77843 (United States); Lucas, S. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415 (United States)

2012-07-01

75

Short time transient periodicities from Cyg X-1  

NASA Technical Reports Server (NTRS)

The temporal behavior of three new events of modulated optical emission from Cyg X1, detected in July 1975, is presented. Short time periodicities in the optical band are investigated. Single photon pulses from the photomultiplier are recorded on magnetic tape together with a very accurate 1 kHz reference frequency. During playback of the tape, the reference signal gives a 1 ms timing to a scaler interfaced with a small processor and the number of photon per millisecond is recorded on a digital tape.

Auriemma, G.; Cardini, D.; Costa, E.; Giovannelli, F.; Ranieri, M.

1976-01-01

76

Impact of Accuracy, Spatial Availability, and Revisit Time of Satellite-Derived Surface Soil Moisture in a Multiscale Ensemble Data Assimilation System  

Microsoft Academic Search

This study evaluates the sensitivity of a multiscale ensemble assimilation system to different configurations of satellite soil moisture observations, namely the retrieval accuracy, spatial availability, and revisit time. We perform horizontally coupled assimilation experiments where pixels are updated not only by observations at the same location but also all in the study domain. Carrying out sensitivity studies within a multiscale

Ming Pan; Eric F. Wood

2010-01-01

77

Short time scale monitoring of SiO sources  

NASA Astrophysics Data System (ADS)

We present the results of a short time scale monitoring of SiO maser emission (v=1 J=1-0 transition) in four known strong sources. These sources were monitored nightly for a period of about a month. The aim of these observations is to investigate the possible presence of variations in the maser lines on time scales of a few days to weeks, due to sound waves propagating out from the central star. If sound waves are responsible for the mass loss of certain cool giants, as suggested by Pijpers & Hearn (1989) and Pijpers & Habing (1989), local variations in density and relative velocity are expected just above the stellar photosphere. These could give rise to variations in any narrow spectral line formed in this region, and therefore in particular in the SiO maser lines. Our observations indicate that variations in the line shape (leading to relative changes in the intensity of about 20%) occur in the SiO emission of Mira type stars, within short time scales of 10-20 days. The main component of the profile variability is consistent with a displacement of the velocity centroid of the dominant maser peaks, by about 1 km/s in the average. Apparent variations in the total line flux were also found, but could be partially due to calibration uncertainties.

Pijpers, F. P.; Pardo, J. R.; Bujarrabal, V.

1994-06-01

78

Short Time Indicators in the Restricted Problem of Three Bodies  

NASA Astrophysics Data System (ADS)

We have applied the method of stretching numbers (or local Lyapounov characteristic numbers), helicity and twist angles in order to distinguish between chaotic and regular domains of the restricted three-body problem. Comparing our results with the corresponding Poincaré's surface of section shows this method to be useful for a quick separation between regular and chaotic domains of the phase space. As we have shown in the case of the planar, circular restricted three-body problem, the method of short-time indicators is very efficient and it needs only 20 iterations per orbit.

Sandor, Zsolt; Balla, Robert; Teger, Ferenc; Erdi, Balint

79

Target time smearing with short transmissions and multipath propagation.  

PubMed

In active sonar the target echo level is often estimated with a propagation model that adds all multipath arrivals. If the (post-correlator) transmitted pulse is short compared to the multipath time spread then there is effectively an extra loss (which may be substantial) since only a few of the paths contribute to the target echo at any one instant. This well known "time-smearing" loss is treated in a self-consistent manner with previous calculations of reverberation [Harrison, J. Acoust. Soc. Am. 114, 2744-2756 (2003)] to estimate the target response and the signal-to-reverberation-ratio. Again isovelocity water, Lambert's law, and reflection loss proportional to angle are assumed. In this important short pulse regime the target response becomes independent of boundary reflection properties but proportional to transmitted pulse length. Thus the signal-to-reverberation-ratio becomes independent of pulse length. The effect on signal-to-ambient-noise is also investigated and the resulting formulas presented in a table. PMID:21895070

Harrison, Chris H

2011-09-01

80

Short-time multifractal analysis: application to biological signals  

NASA Astrophysics Data System (ADS)

Some signals obtained from biological systems evince a great complexity. Recently, new tools which allow the extraction of information from them have been proposed. In particular, multifractal analysis gives a quantification of the degree and distribution of irregularities in a signal. A possible approach for this analysis is the one based on wavelet leaders. In this work, the use of wavelet leader based multifractal analysis in short-time windows is proposed in order to analyze the evolution of the multifractal behavior of biological signals. In particular, applications of this technique to the detection of ischemic episodes in heart rate variability signals and to voice activity detection are examined. It is shown that the study of the time evolution of indexes obtained with the proposed new method gives useful information hidden in the signals.

Leonarduzzi, Roberto F.; Schlotthauer, Gastón; Torres, María E.

2011-09-01

81

A novel method for measuring the residence time distribution in short time scale particulate systems  

Microsoft Academic Search

A novel, non-intrusive method is described for measuring the particle residence time distribution (RTD) in a system with a short mean residence time. The method uses phosphorescent tracer particles activated by a high intensity pulse of light at the inlet. Tracer is detected using a light sensitive photomultiplier unit. Appropriate boundary conditions are maintained by using an annular feeder fluidised

A. T Harris; J. F Davidson; R. B Thorpe

2002-01-01

82

Short time-scale surface changes on Io  

NASA Technical Reports Server (NTRS)

Imaging data from the Voyager 1 and 2 encounters with the Jupiter system provide a data set for the examination of short time-scale variations of surface features on Io. Clear evidence exists for variations near the known eruption sites and for other areas which appeared to have erupted between the encounters. Regions outside the known active eruption sites were examined in order to look for variations in the surface scattering properties which is due to undetected small-scale volcanic activity. The phase functions of many areas are intercompared in order to look for regions with phase functions outside the normal range for satellite surface properties. Areas with unusual scattering properties are related to small-scale eruptions of gas or particles. Determination of the distribution of these areas has strong implications for the resurfacing rates for Io.

Terrile, R. J.

1984-01-01

83

IPS Observations of Short-Time Scale Interplanetary Activity  

NASA Astrophysics Data System (ADS)

We have carried out a program of continuous Interplanetary Scintillation (IPS) monitoring of the interplanetary activity using Ooty Radio Telescope (ORT). From May 1990 to March 1991, during the 22nd, solar maximum, a few radio sources were monitored to provide long stretches of IPS data with a high-time resolution of few minutes. These observations covered 0.3 to 0.8 AU region (12° to 70° elongations) around the sun at several heliographic latitudes. During the observation, we detected 33 short-time scale IPS events which had significant variation in the scintillation index and solar wind velocity. These were considered to be due to travelling interplanetary disturbances. A multi-component model of plasma density enhancement was developed to estimate the geometry and physical properties of these IPS events. Detailed analysis of 20 of these events suggests, 1. fast IPS events were interplanetary signatures of Coronal Mass Ejections (CMEs), 2. the average mass and energy of these events was ˜ 1016 gm and 1033 erg respectively,3. 80% of IPS events were associated with X-ray flares on the sun and 50% were associated with geomagnetic activity at earth. Detailed study of the multicomponent model suggests IPS observations at smaller elongations (hence at higher radio frequencies) are more suited to detect fast-moving interplanetary disturbances such as produced by CMEs.

Gothoskar, Pradeep; Pramesh Rao, A.

1996-03-01

84

Separation of time variant vibration sources by short time coherent output power  

NASA Astrophysics Data System (ADS)

This effort describes the use of time variant coherence causality based analysis to separate the effects of nonstationary time variant vibration excitation sources. A time variant coherence function using the Short Time Fourier Transform (STFT) is first discussed. The concept of a time variant coherent output power for source separation of systems with time variant transfer functions is developed. A parametric study is performed to examine the coherent output power separation capabilities with respect to the data processing parameters. The study guided the selection of the time-frequency processing parameters judged to provide a suitable compromise between the time event localization and output amplitude source separation. The time variant coherent output power is then applied to separate the effects of the two possible excitation sources on the prototype vibration isolation floor. The application was a subscale prototype isolation floor for a proposed vibration sensitive equipment site adjacent to a busy freight rail line. The moving train created time variant transmission paths. As there was a direct line of sight between the prototype floor and the rail line there was an airborne acoustic excitation path in addition to a ground path. The short time coherent output power was applied to separate prototype isolation floor vibration into respective components related to the two candidate sources. The analysis and discussion of the results focuses upon the interpretation and issues in such a complicated realistic environment. Ultimately the application was successful providing an explanation as to why the observed vibration isolation was degraded at higher frequencies.

Trethewey, Martin W.

2011-02-01

85

DECISION TIME HORIZON FOR MUSIC GENRE CLASSIFICATION USING SHORT TIME FEATURES  

Microsoft Academic Search

In this paper music genre classification has been explored with spe- cial emphasis on the decision time horizon and ranking of tapped- delay-line short-time features. Late information fusion as e.g. ma- jority voting is compared with techniques of early information fu- sion1 such as dynamic PCA (DPCA). The most frequently sug- gested features in the literature were employed including mel-

Peter Ahrendt; Anders Meng; Jan Larsen

2004-01-01

86

Revisiting Marey’s Applications of Scientific Moving Image Technologies in the Context of Bergson’s Philosophy: Audio-Visual Mediation and the Experience of Time  

Microsoft Academic Search

This paper revisits some early applications of audio-visual imaging technologies used in physiology in a dialogue with reflections\\u000a on Henri Bergson’s philosophy. It focuses on the aspects of time and memory in relation to spatial representations of movement\\u000a measurements and critically discusses them from the perspective of the observing participant and the public exhibitions of\\u000a scientific films. Departing from an

Martha Blassnigg

2010-01-01

87

Variations in solar Lyman alpha irradiance on short time scales  

NASA Technical Reports Server (NTRS)

Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

Pap, J. M.

1992-01-01

88

Communication: An exact short-time solver for the time-dependent Schro?dinger equation.  

PubMed

The short-time integrator for propagating the time-dependent Schro?dinger equation, which is exact to machine's round off accuracy when the Hamiltonian of the system is time-independent, was applied to solve dynamics processes. This integrator has the old Cayley's form [i.e., the Pade? (1,1) approximation], but is implemented in a spectrally transformed Hamiltonian which was first introduced by Chen and Guo. Two examples are presented for illustration, including calculations of the collision energy-dependent probability passing over a barrier, and interaction process between pulse laser and the I(2) diatomic molecule. PMID:21280676

Sun, Zhigang; Yang, Weitao

2011-01-28

89

Communication: An exact short-time solver for the time-dependent Schr?dinger equation  

PubMed Central

The short-time integrator for propagating the time-dependent Schrödinger equation, which is exact to machine’s round off accuracy when the Hamiltonian of the system is time-independent, was applied to solve dynamics processes. This integrator has the old Cayley’s form [i.e., the Padé (1,1) approximation], but is implemented in a spectrally transformed Hamiltonian which was first introduced by Chen and Guo. Two examples are presented for illustration, including calculations of the collision energy-dependent probability passing over a barrier, and interaction process between pulse laser and the I2 diatomic molecule.

Sun, Zhigang; Yang, Weitao

2011-01-01

90

Infantile facioscapulohumeral muscular dystrophy revisited: Expansion of clinical phenotypes in patients with a very short EcoRI fragment.  

PubMed

Contrary to the classical form, infantile facioscapulohumeral muscular dystrophy (FSHD) usually denotes a severe phenotype and is frequently associated with extramuscular involvements. To elucidate the genotype-phenotype correlation in this severe subgroup, we identified a cohort of nine patients with infantile FSHD who also carried a very short (10-13kb) EcoRI fragment. Their current age ranged from 8 to 33 years and age of onset ranged from 0.4 to 5 years. One patient even manifested his first FSHD-related symptoms at as early as 5 months of age, including inability to smile, poor response to call, and infantile spasms. To date, four patients were wheelchair-bound and six patients had asymmetric weakness. Sensorineural hearing loss and abnormal fundoscopic findings were observed in eight and all of patients respectively. Three with the smallest EcoRI fragments (10-11kb, with normal length being 50-300kb) had mental retardation. Two of these had epilepsy. Cardiac arrhythmias were found in five patients. Restrictive ventilatory defects were observed in seven patients, with one progressing to chronic respiratory failure. Two had swallowing difficulties; one of these required gastrostomy. We identified several rarely reported phenotypes in infantile FSHD, including cardiac arrhythmia, respiratory insufficiency, and swallowing difficulties. There seems to be a correlation between the severity of phenotype and the very short EcoRI fragment in the chromosome 4q35 region. We conclude that the high frequency of multi-organ involvements in this severe FSHD variant suggests the need for an early and multidisciplinary intervention. PMID:23434070

Chen, Tai-Heng; Lai, Yu-Hung; Lee, Pei-Lun; Hsu, Jong-Hau; Goto, Kanako; Hayashi, Yukiko K; Nishino, Ichizo; Lin, Chin-Wen; Shih, Hsiang-Hung; Huang, Chao-Ching; Liang, Wen-Chen; Wang, Wen-Fu; Jong, Yuh-Jyh

2013-04-01

91

Drop tower Beijing and short-time microgravity experiments  

NASA Astrophysics Data System (ADS)

Being an important, large ground-based experiment facility for microgravity science, the drop tower of National Microgravity Lab, CAS was founded in 2003 and, since then, has been un-dertaking the experiments to meet the requirements in microgravity research. The 116 meters high drop tower is located in Zhong Guan Cun district, the scientific town of Beijing. Main components of the facility consist of the drop capsule, release mechanism and deceleration and recovery devices, and were developed with particular technical characteristics. Inner space of the drop tower was not vacuumed during the experiment, and a dual capsule system was adopted. The dual capsule comprises an inner and an outer capsule, and there is a space between in the evacuated atmosphere of 30 Pa. During the free fall, the outer capsule falls in normal atmospheric condition, and the inner capsule falls in vacuum. In addition, a single capsule configuration is also available for experiments w of lower gravity level. The residual acceleration is 10-5go or 10-3g0 related to dual capsule or single capsule arrangement respec-tively. An electric magnetic release system was used to release the capsule from position of 83 meters in height. The designed structure of the release mechanism guaranteed the release disturbance to be small enough. An elastic controllable decelerated system, consisted of the reversible mechanic/electric energy transducer, steel cables and rings, string bag, elastic rub-ber stringassembly, energy dissipation resistance, controlling computer system, was used in the drop tower facility. This system is effective to reduce the impact acceleration to a level of 15g0. The experiment data can be recorded by an on-board data acquisition and control system, and transmitted wirelessly to the control room. Many experiments related to the fluid physics, combustion, material science and other field have been successfully conducted by using the short-time microgravity facility of drop tower in Beijing. At present, the drop tower is play-ing important role in the research of microgravity science and application with more effective, reliable running status.

Wan, S. H.; Yin, M. G.; Guan, X. D.; Lin, H.; Xie, J. C.; Hu, Wen-Rui

92

Short-time versus long-time dynamics of entanglement in quantum lattice models  

NASA Astrophysics Data System (ADS)

We study the short-time evolution of the bipartite entanglement in quantum lattice systems with local interactions in terms of the purity of the reduced density matrix. A lower bound for the purity is derived in terms of the eigenvalue spread of the interaction Hamiltonian between the partitions. Starting from an initially separable state the purity decreases as 1-(t/?)2 (i.e., quadratically in time, with a characteristic timescale ? that is inversely proportional to the boundary size of the subsystem, that is, as an area law). For larger times an exponential lower bound is derived corresponding to the well-known linear-in-time bound of the entanglement entropy. The validity of the derived lower bound is illustrated by comparison to the exact dynamics of a one-dimensional spin lattice system as well as a pair of coupled spin ladders obtained from numerical simulations.

Unanyan, R. G.; Muth, D.; Fleischhauer, M.

2010-02-01

93

STEM: a tool for the analysis of short time series gene expression data  

Microsoft Academic Search

BACKGROUND: Time series microarray experiments are widely used to study dynamical biological processes. Due to the cost of microarray experiments, and also in some cases the limited availability of biological material, about 80% of microarray time series experiments are short (3–8 time points). Previously short time series gene expression data has been mainly analyzed using more general gene expression analysis

Jason Ernst; Ziv Bar-joseph

2006-01-01

94

Incorporating uncertainty into short-term travel time predictions  

Microsoft Academic Search

To improve the quality of travel time information provided to motorists, there is a need to move away from point forecasts of travel time. Specifically, techniques are needed which predict the range of travel times which motorists may experience. This paper focuses on travel time prediction on motorways and evaluates three models for predicting the travel time range in real

Ruimin Li; Geoffrey Rose

2011-01-01

95

Distinctiveness revisited: unpredictable temporal isolation does not benefit short-term serial recall of heard or seen events.  

PubMed

The notion of a link between time and memory is intuitively appealing and forms the core assumption of temporal distinctiveness models. Distinctiveness models predict that items that are temporally isolated from their neighbors at presentation should be recalled better than items that are temporally crowded. By contrast, event-based theories consider time to be incidental to the processes that govern memory, and such theories would not imply a temporal isolation advantage unless participants engaged in a consolidation process (e.g., rehearsal or selective encoding) that exploited the temporal structure of the list. In this report, we examine two studies that assessed the effect of temporal distinctiveness on memory, using auditory (Experiment 1) and auditory and visual (Experiment 2) presentation with unpredictably varying interitem intervals. The results show that with unpredictable intervals temporal isolation does not benefit memory, regardless of presentation modality. PMID:17225515

Nimmo, Lisa M; Lewandowsky, Stephan

2006-09-01

96

Short Hours, Short Shrift. Causes and Consequences of Part-Time Work.  

ERIC Educational Resources Information Center

The recent growth in part-time employment has been propelled by a marked increase in the number of involuntary part-time workers. Most of the growth can be traced to sectoral shifts in the economy toward industries dominated by low-wage, part-time jobs. Many employers hire part-timers to cut costs and gain flexibility, but the creation of more…

Tilly, Chris

97

Healthy Work Revisited: Do Changes in Time Strain Predict Well-Being?  

PubMed Central

Building on Karasek and Theorell (R. Karasek & T. Theorell, 1990, Healthy work: Stress, productivity, and the reconstruction of working life, New York, NY: Basic Books), we theorized and tested the relationship between time strain (work-time demands and control) and seven self-reported health outcomes. We drew on survey data from 550 employees fielded before and 6 months after the implementation of an organizational intervention, the Results Only Work Environment (ROWE) in a white-collar organization. Cross-sectional (Wave 1) models showed psychological time demands and time control measures were related to health outcomes in expected directions. The ROWE intervention did not predict changes in psychological time demands by Wave 2, but did predict increased time control (a sense of time adequacy and schedule control). Statistical models revealed increases in psychological time demands and time adequacy predicted changes in positive (energy, mastery, psychological well-being, self-assessed health) and negative (emotional exhaustion, somatic symptoms, psychological distress) outcomes in expected directions, net of job and home demands and covariates. This study demonstrates the value of including time strain in investigations of the health effects of job conditions. Results encourage longitudinal models of change in psychological time demands as well as time control, along with the development and testing of interventions aimed at reducing time strain in different populations of workers.

Moen, Phyllis; Kelly, Erin L.; Lam, Jack

2013-01-01

98

Revisiting the Development of Time Sharing Using a Dual Motor Task Performance  

ERIC Educational Resources Information Center

In this article, the authors discuss and examine how to develop time sharing using a dual motor task and its effects. They state that when one is required to perform two tasks at the same time (time sharing), an individual may experience difficulty in expressing one or both of the tasks. This phenomenon, known as interference, has been studied…

Getchell, Nancy; Pabreja, Priya

2006-01-01

99

Short time dissolved oxygen dynamics in shallow water ecosystems  

Microsoft Academic Search

Dissolved oxygen evolution over time holds information about the recent and past history of the physics, the chemistry and the biology of aquatic systems. On the daily time scale various phenomena seem to repeat with a sort of regularity, leaving a trace in the further trend of oxygen dynamics. These are the wind calm of nocturnal and early morning hours,

Roberto D’Autilia; Margherita Falcucci; Vincent Hull; Luisa Parrella

2004-01-01

100

Why is the internet traffic bursty in short time scales?  

Microsoft Academic Search

Internet traffic exhibits multifaceted burstiness and correlation structure over a wide span of time scales. Previous work analyzed this structure in terms of heavy-tailed session characteristics, as well as TCP timeouts and congestion avoidance, in relatively long time scales. We focus on shorter scales, typically less than 100-1000 milliseconds. Our objective is to identify the actual mechanisms that are responsible

Hao Jiang; Constantinos Dovrolis

2005-01-01

101

The origin of TCP traffic burstiness in short time scales  

Microsoft Academic Search

Internet traffic exhibits multifaceted burstiness and correlation structure over a wide span of time scales. Previous work analyzed this structure in terms of heavy-tailed session characteristics, as well as TCP timeouts and congestion avoid- ance, in relatively long time scales. We focus on shorter scales, typically less than 100-1000 milliseconds. Our objective is to identify the actual mechanisms that are

Hao Jiang; Constantinos Dovrolis

2004-01-01

102

Time sequence and the recurrence models for large earthquakes along the Nankai trough revisited  

Microsoft Academic Search

It is suggested that time sequence of earthquakes can be explained by the time-predictable recurrence model rather than the slip-predictable recurrence model. However, the reliability of the model depends primarily on data accuracy; missing large events seriously affect the evaluation of the models. Although the time-predictable model can explain the recent three large events along the Nankai trough back to

Hiroyuki Kumagai

1996-01-01

103

Time sequence and the recurrence models for large earthquakes along the Nankai Trough revisited  

Microsoft Academic Search

It is suggested that time sequence of earthquakes can be explained by the time-predictable recurrence model rather than the slip-predictable recurrence model. However, the reliability of the model depends primarily on data accuracy; missing large events seriously affect the evaluation of the models. Although the time-predictable model can explain the recent three large events along the Nankai trough back to

Hiroyuki Kumagai

1996-01-01

104

The Web Versus Digital Libraries: Time to Revisit This Once Hot Topic  

Microsoft Academic Search

At the end of last century (Internet time elapses much quicker than normal time, and it already looks like a long time ago),\\u000a the “information explosion” on the Web on one side, and the flourishing of research activities on digital library technologies\\u000a on the other, spurred heated discussions about the future of traditional libraries. The view of one camp was

Vittore Casarosa; Jill Cousins; Anna Maria Tammaro; Yannis E. Ioannidis

2008-01-01

105

The water–gas-shift reaction at short contact times  

Microsoft Academic Search

We have examined the water–gas-shift reaction over noble metals and metals with ceria for catalyst contact times between 0.008 and 0.05 s for temperatures from 300 to 1000°C. With reactants of CO, H2, and H2O at a 1\\/2\\/4 composition, the reaction approached equilibrium at these contact times for temperatures as low as 380°C, which corresponds to a 50\\/1 H2\\/CO ratio. All

C Wheeler; A Jhalani; E. J Klein; S Tummala; L. D Schmidt

2004-01-01

106

The Galaxy Viewed at Very Short Time-Scales  

Microsoft Academic Search

We present high time-resolution astronomical observations recorded with the Berkeley Visible Image Tube (BVIT) photon counting detector mounted on the 10m South African Large Telescope (SALT). Relative B and V-band photometric fluxes were obtained as a function of time for targets that included Polar-type cataclysmic variables (UZ For, OY Car, V1033Cen), low-mass X-ray binaries (GX 339-4, UY Vol), pulsars (PSR

Navid Radnia; O. Siegmund; B. Welsh; J. Mcphate; D. Rogers; P. Charles; D. Buckley

2010-01-01

107

On the simulation of protein folding by short time scale molecular dynamics and distributed computing  

Microsoft Academic Search

There are proposals to overcome the current incompatibilities between the time scales of protein folding and molecular dynamics simulation by using a large number of short simulations of only tens of nanoseconds (distributed computing). According to the principles of first-order kinetic processes, a sufficiently large number of short simulations will include, de facto, a small number of long time scale

Alan R. Fersht

2002-01-01

108

Nutrient timing revisited: is there a post-exercise anabolic window?  

PubMed Central

Nutrient timing is a popular nutritional strategy that involves the consumption of combinations of nutrients--primarily protein and carbohydrate--in and around an exercise session. Some have claimed that this approach can produce dramatic improvements in body composition. It has even been postulated that the timing of nutritional consumption may be more important than the absolute daily intake of nutrients. The post-exercise period is widely considered the most critical part of nutrient timing. Theoretically, consuming the proper ratio of nutrients during this time not only initiates the rebuilding of damaged muscle tissue and restoration of energy reserves, but it does so in a supercompensated fashion that enhances both body composition and exercise performance. Several researchers have made reference to an anabolic “window of opportunity” whereby a limited time exists after training to optimize training-related muscular adaptations. However, the importance - and even the existence - of a post-exercise ‘window’ can vary according to a number of factors. Not only is nutrient timing research open to question in terms of applicability, but recent evidence has directly challenged the classical view of the relevance of post-exercise nutritional intake with respect to anabolism. Therefore, the purpose of this paper will be twofold: 1) to review the existing literature on the effects of nutrient timing with respect to post-exercise muscular adaptations, and; 2) to draw relevant conclusions that allow practical, evidence-based nutritional recommendations to be made for maximizing the anabolic response to exercise.

2013-01-01

109

The time-dependent quantum harmonic oscillator revisited: Applications to quantum field theory  

NASA Astrophysics Data System (ADS)

In this article, we formulate the study of the unitary time evolution of systems consisting of an infinite number of uncoupled time-dependent harmonic oscillators in mathematically rigorous terms. We base this analysis on the theory of a single one-dimensional time-dependent oscillator, for which we first summarize some basic results concerning the unitary implementability of the dynamics. This is done by employing techniques different from those used so far to derive the Feynman propagator. In particular, we calculate the transition amplitudes for the usual harmonic oscillator eigenstates and define suitable semiclassical states for some physically relevant models. We then explore the possible extension of this study to infinite dimensional dynamical systems. Specifically, we construct Schrödinger functional representations in terms of appropriate probability spaces, analyze the unitarity of the time evolution, and probe the existence of semiclassical states for a wide range of physical systems, particularly, the well-known Minkowskian free scalar fields and Gowdy cosmological models.

Vergel, Daniel Gómez; Villaseñor, Eduardo J. S.

2009-06-01

110

Future-time perspective in adolescence: The present of things future revisited  

Microsoft Academic Search

Several theorists have suggested that the observed changes in adolescent future-time perspective are due to the emergence of formal-operations reasoning [e. g., T. J. Cottle and S. Klineberg (1974),The Present of Things Future, Free Press-Macmillan, New York; P. Fraisse (1963),The Psychology of Time, Harper & Row, New York; H. Hartmann (1958),Ego Psychology and the Problem of Adaptation, International Universities Press,

A. L. Greene

1986-01-01

111

Improved initial value estimation for short echo time magnetic resonance spectroscopy spectral analysis using short T2 signal attenuation.  

PubMed

Robust spectral analysis of magnetic resonance spectroscopy data frequently uses a spectral model with prior metabolite signal information within a nonlinear least squares optimization algorithm. Starting values for the spectral model greatly influence the final results. Short echo time magnetic resonance spectroscopy contains broad signals that overlap with metabolite signals, complicating the estimation of starting values. We describe a method for more robust initial value estimation using a filter to attenuate short T(2) signal contributions (e.g., macromolecules or residual lipids). The method attenuates signals by truncating early points in the data set. Metabolite peak estimation is simplified by the removal of broad, short T(2) signals, and corrections for metabolite signal truncation are described. Short echo time simulated Monte Carlo data and in vivo data were used to validate the method. Areas for metabolite signals in the Monte Carlo data with singlet (N-acetylaspartate, creatine, choline) and singlet-like (myo-inositol) resonances were estimated within 10% of actual value for various metabolite line widths, signal-to-noise ratios, and underlying broad signal contributions. Initial value estimates of in vivo magnetic resonance spectroscopy data were within 14% of metabolite area ratios relative to the creatine peak fitted using established magnetic resonance spectroscopy spectral analysis software. PMID:21858869

Steinberg, Jeffrey; Soher, Brian J

2012-05-01

112

Lakatos Revisited.  

ERIC Educational Resources Information Center

Revisits and reviews Imre Lakatos' ideas on "Falsification and the Methodology of Scientific Research Programmes." Suggests that Lakatos' framework offers an insightful way of looking at the relationship between theory and research that is relevant not only for evaluating research programs in theoretical physics, but in the social sciences as…

Court, Deborah

1999-01-01

113

FUNDAMENTAL SOLUTION OF THE GENERALIZED THERMOELASTIC PROBLEM FOR SHORT TIMES  

Microsoft Academic Search

The solution of the problem of determining stress and temperature distributions with a continuous source of heat in an infinite elastic body governed by the equations of generalized thermoelasticity are obtained by using the Laplace transform technique. Inverse transforms are obtained in an approximate manner for small values of time. Numerical computations for some particular cases are carried out and

Hany H. Sherief

1986-01-01

114

A study of Venus rotation at short time scale  

Microsoft Academic Search

Venus which can be considered as the twin sister of the Earth in view of its global characteristics (size, density) has been the subject of many investigations to understand its slow retrograde rotation (243d) and its rather small obliquity (2°.63). Many of these studies concern the evolution of Venus rotation at very long time scales. Here we present a complete

L. Cottereau; J. Souchay

2009-01-01

115

Revisiting random walks in fractal media: on the occurrence of time discrete scale invariance.  

PubMed

This paper addresses the kinetic behavior of random walks in fractal media. We perform extensive numerical simulations of both single and annihilating random walkers on several Sierpinski carpets, in order to study the time behavior of three observables: the average number of distinct sites visited by a single walker, the mean-square displacement from the origin, and the density of annihilating random walkers. We found that the time behavior of those observables is given by a power law modulated by soft logarithmic-periodic oscillations. We conjecture that logarithmic-periodic oscillations are a manifestation of a time domain discrete scale iNvariance (DSI) that occurs as a consequence of the spatial DSI of the substrate. Our conjecture implies that the logarithmic periods of oscillations in space and time domains are linked by a dynamic exponent z, through z=log(tau)/log(b(1)), where tau and b(1) are the fundamental scaling ratios of the DSI symmetry in the time and space domains, respectively. We use this relationship in order to compute z for different observables and fractals. Furthermore, we check the values obtained with independent measurements provided by the power-law behavior of the mean-square displacement with time [R(2)(t) proportional variant t(2/z)]. The very good agreement obtained between both computations of the z exponent gives strong support to the idea of an intimate interplay between spatial and time symmetry properties that we expect will have a quite general scope. We expect that the application of the outlined concepts in the field of dynamic processes in fractal media will stimulate further research. PMID:18248004

Bab, M A; Fabricius, G; Albano, Ezequiel V

2008-01-28

116

Revisiting random walks in fractal media: On the occurrence of time discrete scale invariance  

NASA Astrophysics Data System (ADS)

This paper addresses the kinetic behavior of random walks in fractal media. We perform extensive numerical simulations of both single and annihilating random walkers on several Sierpinski carpets, in order to study the time behavior of three observables: the average number of distinct sites visited by a single walker, the mean-square displacement from the origin, and the density of annihilating random walkers. We found that the time behavior of those observables is given by a power law modulated by soft logarithmic-periodic oscillations. We conjecture that logarithmic-periodic oscillations are a manifestation of a time domain discrete scale iNvariance (DSI) that occurs as a consequence of the spatial DSI of the substrate. Our conjecture implies that the logarithmic periods of oscillations in space and time domains are linked by a dynamic exponent z, through z=log(?)/log(b1), where ? and b1 are the fundamental scaling ratios of the DSI symmetry in the time and space domains, respectively. We use this relationship in order to compute z for different observables and fractals. Furthermore, we check the values obtained with independent measurements provided by the power-law behavior of the mean-square displacement with time [R2(t)~t2/z]. The very good agreement obtained between both computations of the z exponent gives strong support to the idea of an intimate interplay between spatial and time symmetry properties that we expect will have a quite general scope. We expect that the application of the outlined concepts in the field of dynamic processes in fractal media will stimulate further research.

Bab, M. A.; Fabricius, G.; Albano, Ezequiel V.

2008-01-01

117

Short-time dynamics of correlated quantum Coulomb systems  

NASA Astrophysics Data System (ADS)

Strong correlations in dense Coulomb systems are attracting increasing interest in many fields ranging from dense astrophysical plasmas, dusty plasmas and semiconductors to metal clusters and ultracold trapped ions [1]. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) and many-particle correlations such as Coulomb and Yukawa liquids and crystals. Of particular current interest is the response of these systems to short excitations generated e.g. by femtosecond laser pulses and giving rise to ultrafast relaxation processes and build up of binary correlations. The proper theoretical tool are non-Markovian quantum kinetic equations [1,2] which can be derived from Nonequilibrium Green's Functions (NEGF) and are now successfully solved numerically for dense plasmas and semiconductors [3], correlated electrons [4] and other many-body systems with moderate correlations [5]. This method is well suited to compute the nonlinear response to strong fields selfconsistently including many-body effects [6]. Finally, we discuss recent extensions of the NEGF-computations to the dynamics of strongly correlated Coulomb systems, such as single atoms and molecules [7] and electron and exciton Wigner crystals in quantum dots [8,9]. [1] H. Haug and A.-P. Jauho, Quantum Kinetics in Transport and Optics of Semiconductors, Springer 1996; M. Bonitz Quantum Kinetic Theory, Teubner, Stuttgart/Leipzig 1998; [2] Progress in Nonequilibrium Green's Functions III, M. Bonitz and A. Filinov (Eds.), J. Phys. Conf. Ser. vol. 35 (2006); [3] M. Bonitz et al. Journal of Physics: Condensed Matter 8, 6057 (1996); R. Binder, H.S. K"ohler, and M. Bonitz, Phys. Rev. B 55, 5110 (1997); [4] N.H. Kwong, and M. Bonitz, Phys. Rev. Lett. 84, 1768 (2000); [5] Introduction to Computational Methods for Many-Body Systems, M. Bonitz and D. Semkat (eds.), Rinton Press, Princeton (2006); [6] H. Haberland, M. Bonitz, and D. Kremp, Phys. Rev. E 64, 026405 (2001); [7] N.E. Dahlen, A. Stan and R. van Leeuwen, p. 324 in Ref. 2.; [8] A. Filinov, M. Bonitz, and Yu. Lozovik, Phys. Rev. Lett. 86, 3851 (2001); [9] K. Balzer, N.E. Dahlen, R. van Leeuwen, and M. Bonitz, to be published

Bonitz, Michael

2007-03-01

118

IPS observations of short-time scale interplanetary activity  

Microsoft Academic Search

We have carried out a program of continuous Interplanetary Scintillation (IPS) monitoring of the interplanetary activity using Ooty Radio Telescope (ORT). From May 1990 to March 1991, during the 22nd, solar maximum, a few radio sources were monitored to provide long stretches of IPS data with a high-time resolution of few minutes. These observations covered 0.3 to 0.8 AU region

Pradeep Gothoskar; A. Pramesh Rao

1996-01-01

119

Temporal moments revisited: Why there is no better way for physically based model reduction in time  

NASA Astrophysics Data System (ADS)

Many hydro(geo)logical problems are highly complex in space and time, coupled with scale issues, variability, and uncertainty. Especially time-dependent models often consume enormous computational resources, but model reduction techniques can alleviate this problem. Temporal moments (TM) offer an approach to reduce the time demands of transient hydro(geo)logical simulations. TM reduce transient governing equations to steady state and directly simulate the temporal characteristics of the system, if the equations are linear and coefficients are time independent. This is achieved by an integral transform, projecting the dynamic system response onto monomials in time. In comparison to classical approaches of model reduction that involve orthogonal base functions, however, the monomials for TM are nonorthogonal, which might impair the quality and efficiency of model reduction. Thus, we raise the question of whether there are more suitable temporal base functions than the monomials that lead to TM. In this work, we will derive theoretically that there is only a limited class of temporal base functions that can reduce hydro(geo)logical models. By comparing those to TM we conclude that, in terms of gained efficiency versus maintained accuracy, TM are the best possible choice. While our theoretical results hold for all systems of linear partial or ordinary differential equations (PDEs, ODEs) with any order of space and time derivatives, we illustrate our study with an example of pumping tests in a confined aquifer. For that case, we demonstrate that two (four) TM are sufficient to represent more than 80% (90%) of the dynamic behavior, and that the information content strictly increases with increasing TM order.

Leube, P. C.; Nowak, W.; Schneider, G.

2012-11-01

120

Mass Spectrometric Immunoassay Revisited  

NASA Astrophysics Data System (ADS)

The progressive understanding and improvement of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), realized over the years through the considerable efforts of Dr. Marvin Vestal, have made possible numerous comparable efforts involving its application in the biological sciences. Here we revisit the concepts behind one such analytical approach, Mass Spectrometric Immunoassay, which is designed to selectively detect and quantify proteins present in biological milieu.

Nelson, Randall W.; Borges, Chad R.

2011-06-01

121

Estimating Mean First Passage Time of Biased Random Walks with Short Relaxation Time on Complex Networks  

PubMed Central

Biased random walk has been studied extensively over the past decade especially in the transport and communication networks communities. The mean first passage time (MFPT) of a biased random walk is an important performance indicator in those domains. While the fundamental matrix approach gives precise solution to MFPT, the computation is expensive and the solution lacks interpretability. Other approaches based on the Mean Field Theory relate MFPT to the node degree alone. However, nodes with the same degree may have very different local weight distribution, which may result in vastly different MFPT. We derive an approximate bound to the MFPT of biased random walk with short relaxation time on complex network where the biases are controlled by arbitrarily assigned node weights. We show that the MFPT of a node in this general case is closely related to not only its node degree, but also its local weight distribution. The MFPTs obtained from computer simulations also agree with the new theoretical analysis. Our result enables fast estimation of MFPT, which is useful especially to differentiate between nodes that have very different local node weight distribution even though they share the same node degrees.

Lee, Zhuo Qi; Hsu, Wen-Jing; Lin, Miao

2014-01-01

122

Short residence time coal liquefaction process including catalytic hydrogenation  

DOEpatents

Normally solid dissolved coal product and a distillate liquid product are produced by continuously passing a feed slurry comprising raw feed coal and a recycle solvent oil and/or slurry together with hydrogen to a preheating-reaction zone, the hydrogen pressure in the preheating-reaction zone being at least 1,500 psig (105 kg/cm[sup 2]), reacting the slurry in the preheating-reaction zone at a temperature in the range of between about 455 and about 500 C to dissolve the coal to form normally liquid coal and normally solid dissolved coal. A total slurry residence time is maintained in the reaction zone ranging from a finite value from about 0 to about 0.2 hour, and reaction effluent is continuously and directly contacted with a quenching fluid to substantially immediately reduce the temperature of the reaction effluent to below 425 C to substantially inhibit polymerization so that the yield of insoluble organic matter comprises less than 9 weight percent of said feed coal on a moisture-free basis. The reaction is performed under conditions of temperature, hydrogen pressure and residence time such that the quantity of distillate liquid boiling within the range C[sub 5]-454 C is an amount at least equal to that obtainable by performing the process under the same condition except for a longer total slurry residence time, e.g., 0.3 hour. Solvent boiling range liquid is separated from the reaction effluent and recycled as process solvent. The amount of solvent boiling range liquid is sufficient to provide at least 80 weight percent of that required to maintain the process in overall solvent balance. 6 figs.

Anderson, R.P.; Schmalzer, D.K.; Wright, C.H.

1982-05-18

123

Short residence time coal liquefaction process including catalytic hydrogenation  

DOEpatents

Normally solid dissolved coal product and a distillate liquid product are produced by continuously passing a feed slurry comprising raw feed coal and a recycle solvent oil and/or slurry together with hydrogen to a preheating-reaction zone (26, alone, or 26 together with 42), the hydrogen pressure in the preheating-reaction zone being at least 1500 psig (105 kg/cm.sup.2), reacting the slurry in the preheating-reaction zone (26, or 26 with 42) at a temperature in the range of between about 455.degree. and about 500.degree. C. to dissolve the coal to form normally liquid coal and normally solid dissolved coal. A total slurry residence time is maintained in the reaction zone ranging from a finite value from about 0 to about 0.2 hour, and reaction effluent is continuously and directly contacted with a quenching fluid (40, 68) to substantially immediately reduce the temperature of the reaction effluent to below 425.degree. C. to substantially inhibit polymerization so that the yield of insoluble organic matter comprises less than 9 weight percent of said feed coal on a moisture-free basis. The reaction is performed under conditions of temperature, hydrogen pressure and residence time such that the quantity of distillate liquid boiling within the range C.sub.5 -454.degree. C. is an amount at least equal to that obtainable by performing the process under the same condition except for a longer total slurry residence time, e.g., 0.3 hour. Solvent boiling range liquid is separated from the reaction effluent (83) and recycled as process solvent (16). The amount of solvent boiling range liquid is sufficient to provide at least 80 weight percent of that required to maintain the process in overall solvent balance.

Anderson, Raymond P. (Overland Park, KS); Schmalzer, David K. (Englewood, CO); Wright, Charles H. (Overland Park, KS)

1982-05-18

124

Max Frei theory revisitation: does really strokes depth change along time?  

PubMed

A serious problem in questioned document examination is to establish the age of written lines. With respect to paper dating, in the past, Max Frei theory (based only on microscope analysis) claimed that strokes are time-dependent. Therefore, according to this theory, it has been asserted that from the analysis of the strokes depth changes it is possible to try to date the handwritten document (to find out that the document is older than ...). In the present work, we investigate the strokes depth change by a laser profilometer considering not only the time but also microclimatic variations. First, we analyze the stability of stroke characteristics along the time. In particular, we demonstrate that if the document is preserved without change of temperature and humidity, the depth of the strokes has not appreciable changes. In this way, we have the purpose to verify the real possibility of documents dating by means of Max Frei theory. Subsequently, we test how the 3D profile of strokes changes in connection with the microclimatic variations. In particular, we test humidity variations. With this experiment, we show that humidity variations reduce the strokes depth. Moreover, this effect shows a non-linear trend, leaving a hysteresis on the depth. Finally, we show that the analysis of 3D stroke profile is unable to determine the age of documents. PMID:16887309

Schirripa Spagnolo, Giuseppe; Zavattaro, Davide; De Santis, Michele; Ferrillo, Luca Gennaro

2007-04-11

125

Short-time forecasting of the system magnetosheath -magnetosphere  

NASA Astrophysics Data System (ADS)

We report on the efforts to optimize the performance of a new magnetosphere-magnetosheath model in order to achieve at least 30 minutes forecasting advance of the near-Earth space. The utilized model, developed at the Institute of Mechanics, Bulgarian Academy of Sciences, consists of two models, describing self-consistently the magnetosheath-magnetosphere system. The 3D magnetosheath modul receives the flow distribution at the magnetosheath region (in gasdynamic approach). The magnetosphere model is a modification of the Tsyganenko magnetic field model with numerically calculated shielding field and boundary. The locations and shapes of the bow shock and magnetopause are also described as a part of the solution. The 3D form of the magnetopause (generally non-axially-symmetric), including the cusp indentation, influences essentially the flow. Input data for the whole model are density, temperature, flow velocity and interplanetary magnetic field (IMF). A complementary part of the system is a set of algorithms and programs, making use of the available in Internet near real time solar wind monitoring in L1 (currently performed by ACE). In order to modernize and extend the existing simulation software, several performance optimization techniques were applied to the FORTRAN source code. Also parts of the code are being incrementally parallelized using OpenMP directives. The simulations run on several multicore x86-64 machines under 64-bit Linux OS. The traveling time of the solar wind from L1 to the Earth is enough for running the magnetosheath-magnetosphere problem. Numerical experiments, performed on different configuration of the computer platform are discussed.

Dobreva, Polya; Iliev, Hristo; Grigorov, Krum; Koitchev, Detelin; Keremidarska, Valentina; Kartalev, Monio

126

Revisiting the Stark Broadening by fluctuating electric fields using the Continuous Time Random Walk Theory  

NASA Astrophysics Data System (ADS)

Stark broadening of atomic lines in plasmas is calculated by modelling the plasma stochastic electric field using the CTRW approach [1,2]. This allows retaining non Markovian terms in the Schrödinger equation averaged over the electric field fluctuations. As an application we consider a special case of a non separable CTRW process, the so called Kangaroo process [3]. An analytic expression for the line profile is presented for arbitrary waiting time distribution functions. A preliminary application to the hydrogen Lyman ? line is discussed.

Capes, H.; Christova, M.; Boland, D.; Catoire, F.; Godbert-Mouret, L.; Koubiti, M.; Mekkaoui, A.; Rosato, J.; Marandet, Y.; Stamm, R.

2010-10-01

127

Revisiting chronodisruption: when the physiological nexus between internal and external times splits in humans  

NASA Astrophysics Data System (ADS)

In this Concepts & Synthesis paper, we expand the definition of chronodisruption in humans by proposing that it can be operationalized as the split nexus of internal and external times. With this premise, we suggest how chronotype may be used as a temporal marker (chronomarker) of exposure to chronodisruption in studies of cancer, and beyond, offer cancer risk predictions for observational research on the basis of a chronotype-related hypothesis and corollary, and point to first empirical data in humans. In an a priori way, we examine possible outcomes and perspectives for preventive measures following from our rationale and the suggested chronobiology-driven studies and close with overall advances of chronodisruption research.

Erren, Thomas C.; Reiter, Russel J.

2013-04-01

128

Residence time and collision statistics for exponential flights: the rod problem revisited.  

PubMed

Many random transport phenomena, such as radiation propagation, chemical-biological species migration, or electron motion, can be described in terms of particles performing exponential flights. For such processes, we sketch a general approach (based on the Feynman-Kac formalism) that is amenable to explicit expressions for the moments of the number of collisions and the residence time that the walker spends in a given volume as a function of the particle equilibrium distribution. We then illustrate the proposed method in the case of the so-called rod problem (a one-dimensional system), and discuss the relevance of the obtained results in the context of Monte Carlo estimators. PMID:21928981

Zoia, A; Dumonteil, E; Mazzolo, A

2011-08-01

129

Blankenbach 3 revisited: intricate time-dependent patterns in a simple model of mantle convection  

NASA Astrophysics Data System (ADS)

We evaluate time-dependent nature of mantle convection using a simple 2D Cartesian model with internal heating based on the benchmark case 3 in Blankenbach et al. (Geophysical Journal International, 1989). We are particularly interested in the bifurcation patterns of the Vrms-Nu phase plot for Rayleigh numbers (Ra) around the benchmark value (Ra = 2.16×105), but more information is disclosed when we go to higher Ra (up to 8×105). We also investigate the role of the boundary conditions, for which we change to periodic boundary conditions for a second bifurcation study. We find an intricate pattern in the behavior of the heat flow (as measured by the Nusselt number Nu(t)) and the kinetic energy (as measured by Vrms(t)) which include period doubling, break down of periodic into episodic flow and reorganization into periodic flow at higher Ra. Two patterns of bifurcation are found. One is the period doubling pattern, described in Blankenbach et al. 1989 and referred to as P2-P4 bifurcation. The period doubling results from the differentiation of existing limit points of the time series of Nu or Vrms. The other pattern is period-preserving, which is found at higher Ra number in this study. In the period-preserving bifurcation, the new limit points (peak and valley) of the Nu and Vrms time series showed up as a twist in the monotonic intervals between a peak and valley. In this case the period doesn’t change. Both of the two patterns are observed in the models with the two types of boundary conditions (reflective and periodic). At a given Ra, different solutions can be obtained with different initial conditions. The initial condition is usually a solution with its Ra in the neighborhood, and with this neighborhood searching method, we were able to span the bifurcation plot (Ra-limit points of Nu(t) or Vrms(t)) to the range of Ra = 1×105~8×105 with both two boundary conditions. In this process, hysteresis is observed as expected in dynamic system, and the overlap of different trend of solutions are large enough to demonstrate tough competition between them. Limit points of Vrms time series obtained at same conditions with Blanckenbach case 3 with different Rayleigh numbers, showing bifurcation.

Hu, Z.; van Keken, P. E.

2010-12-01

130

Circinus X-1 revisited: Fast-timing properties in relation to spectral state  

NASA Technical Reports Server (NTRS)

We have studied the X-ray spectral and fast-timing variations of Cir X-1 by performing a homogenous analysis of all EXOSAT ME data on this source using X-ray hardness-intensity diagrams (HIDs), color-color diagrams (CDs), and power spectra. Cir X-1 exhibits a wide range of power spectral shapes and a large variety in X-ray spectral shapes. At different epochs the power spectra variously resemble those of an atoll source, a Z source, a black-hole candidate, or are unlike any of these. At some epochs one-dimensional connected-branch patterns are seen in HID and CD, and at other times more complex structures are found. We interpret the complex behavior of Cir X-1 in terms of a model where accretion rate, orbital phase and epoch are the main determinants of the source behavior, and where the unique properties of the source are due to two special circumstances: (1) the source is the only known atoll source (accreting neutron star with a very low magnetic field) that can reach the Eddington critical accretion rate, and (2) it has a unique, highly eccentric and probably precessing orbit. Property (1) makes Cir X-1 a very important source for our understanding of the similarities in the observable properties of neutron stars and black holes as it allows to separate out black hole signatures from properties that are merely due to the presence of accretion compact with a low magnetic field.

Oosterbroek, T.; Van Der Klis, M.; Kuulkers, E.; Van Paradijs, J.; Lewin, W. H. G.

1995-01-01

131

Short-Time Autoregressive (STAR) Modeling for Operational Modal Analysis of Non-stationary Vibration  

Microsoft Academic Search

\\u000a In this chapter, a method based on an autoregressive model in a short-time scheme is developed for the modal analysis of vibrating\\u000a structures whose properties may vary with time and is called Short-Time AutoRegressive (STAR) method. This new method allows\\u000a for the successful modeling and identification of an output-only modal analysis. The originality of the proposed method lies\\u000a in its

V.-H. Vu; M. Thomas; A. A. Lakis; L. Marcouiller

132

On the non-periodic variations of the Earth's rotation parameter in short time scale.  

NASA Astrophysics Data System (ADS)

The non-periodic variations in short time scale of the Earth's rotation parameter between Jan. 1980 and July 1981 are analysed. The used materials are the optical observations of the time and latitude of the world, presented by the IPMS. The behaviour of UT1-TAI is very complicated, and contains the oscillations of about 13 days period. Concerning the pole positions x and y, the significant variations in short time scale are very sparse.

Sekiguchi, N.

133

Short time-scale variability of chromospheric Ca II in late-type stars  

Microsoft Academic Search

We have investigated short time-scale variability of singly ionized calcium chromospheric emission in a few late-type stars. Emission-line variations with time scales of a few minutes to hours are seen in ..cap alpha.. Tau (K5 III), lambda and (G8 III--IV), and epsilon Eri (K2 V). The existence of substantial chromospheric flux changes (10³°⁻⁻¹°sup 32\\/ ergs) over short periods of time

S. L. Baliunas; L. Hartmann; A. H. Waughan; W. Liller; A. K. Dupree

1981-01-01

134

Late-time tails in the Reissner-Nordstroem spacetime revisited  

SciTech Connect

We propose that the late-time tail problem in the Reissner-Nordstroem (RN) spacetime is dual to a tail problem in the Schwarzschild spacetime with a different initial data set: at a fixed observation point the asymptotic decay rate of the fields are equal. This duality is used to find the decay rate for tails in RN. This decay rate is exactly as in Schwarzschild, including the case of the extremely-charged RN spacetime (ERN). The only case where any deviation from the Schwarzschild decay rate is found is the case of the tails along the event horizon of an ERN spacetime, where the decay rate is the same as at future null infinity. As observed at a fixed location, the decay rate in ERN is the same as in Schwarzschild. We verify these expectations with numerical simulations.

Blaksley, Carl J. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Burko, Lior M. [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States)

2007-11-15

135

BOOK REVIEW: Nonequilibrium Physics at Short Time Scales: Formation of Correlations  

Microsoft Academic Search

It is a happy situation when similar concepts and theoretical techniques can be applied to widely different physical systems because of a deep similarity in the situations being studied. The book illustrates this well; it focuses on the description of correlations in quantum systems out of equilibrium at very short time scales, prompted by experiments with short laser pulses in

K. Morawetz

2005-01-01

136

Magnetic Reconnection Sites Observed by the Cluster Spacecraft: Measurement of Short time scale electron effects  

Microsoft Academic Search

Several events have been observed by the Cluster spacecraft passing close to magnetic reconnection sites in the tail and magnetopause when the fleet configuration is at short spatial scale (spacecraft separation approximately 100 km). These events are studied in the context of corresponding short time scale electron behaviour which contribute to and result from the reconnection process. This is done

A. M. Buckley; T. C. Carozzi; M. P. Gough; E. C. Chambers

2004-01-01

137

Revisiting Decidability and Optimum Reachability for Multi-Priced Timed Automata  

NASA Astrophysics Data System (ADS)

We investigate the optimum reachability problem for Multi-Priced Timed Automata (MPTA) that admit both positive and negative costs on edges and locations, thus bridging the gap between the results of Bouyer et al. (2007) and of Larsen and Rasmussen (2008). Our contributions are the following: (1) We show that even the location reachability problem is undecidable for MPTA equipped with both positive and negative costs, provided the costs are subject to a bounded budget, in the sense that paths of the underlying Multi-Priced Transition System (MPTS) that operationally exceed the budget are considered as not being viable. This undecidability result follows from an encoding of Stop-Watch Automata using such MPTA, and applies to MPTA with as few as two cost variables, and even when no costs are incurred upon taking edges. (2) We then restrict the MPTA such that each viable quasi-cyclic path of the underlying MPTS incurs a minimum absolute cost. Under such a condition, the location reachability problem is shown to be decidable and the optimum cost is shown to be computable for MPTA with positive and negative costs and a bounded budget. These results follow from a reduction of the optimum reachability problem to the solution of a linear constraint system representing the path conditions over a finite number of viable paths of bounded length.

Fränzle, Martin; Swaminathan, Mani

138

Thermal Casimir effect for rectangular cavities inside (D+1)-dimensional Minkowski space-time revisited  

NASA Astrophysics Data System (ADS)

We reconsider the thermal scalar Casimir effect for p-dimensional rectangular cavity inside (D+1)-dimensional Minkowski space-time and clarify the ambiguity in the regularization of the temperature-dependent part of the free energy. We derive rigorously the regularization of the temperature-dependent part of the free energy by making use of the Abel-Plana formula repeatedly and get the explicit expression of the terms to be subtracted. In the cases of D = 3, p = 1 and D = 3, p = 3, we precisely recover the results of parallel plates and three-dimensional box in the literature. Furthermore, for D>p and D = p cases with periodic, Dirichlet and Neumann boundary conditions, we give the explicit expressions of the Casimir free energy in both low temperature (small separations) and high temperature (large separations) regimes, through which the asymptotic behavior of the free energy changing with temperature and the side length is easy to see. We find that for D>p, with the side length going to infinity, the Casimir free energy tends to positive or negative constants or zero, depending on the boundary conditions. But for D = p, the leading term of the Casimir free energy for all three boundary conditions is a logarithmic function of the side length. We also discuss the thermal Casimir force changing with temperature and the side length in different cases and find that when the side length goes to infinity, the force always tends to be zero for different boundary conditions regardless of D>p or D = p. The Casimir free energy and force at high temperature limit behave asymptotically alike that they are proportional to the temperature, be they positive (repulsive) or negative (attractive) in different cases. Our study may be helpful in providing a comprehensive and complete understanding of this old problem.

Lin, Rui-Hui; Zhai, Xiang-Hua

2014-03-01

139

The behaviour of tungsten during mantle melting revisited with implications for planetary differentiation time scales  

NASA Astrophysics Data System (ADS)

Tungsten is a moderately siderophile high-field-strength element that is hydrophile and widely regarded as highly incompatible during mantle melting. In an effort to extend empirical knowledge regarding the behaviour of W during the latter process, we report new high-precision trace element data (W, Th, U, Ba, La, Sm) that represent both terrestrial and planetary reservoirs: MORB (11), abyssal peridotites (8), eucrite basalts (3), and carbonaceous chondrites (8). A full trace element suite is also reported for Cordilleran Permian ophiolite peridotites (12) to better constrain the behaviour of W in the upper mantle. In addition, we report our long-term averages for a number of USGS (BIR-1, BHVO-1, BHVO-2, PCC-1, DTS-1) and GSJ (JA-3, JP-1) standard reference materials, some of which we conclude to be heterogeneous and contaminated with respect to W. The most significant finding of this study is that many of the highly depleted upper mantle peridotites contain far higher W concentrations than expected. In the absence of convincing indications for alteration, re-enrichment or contamination, we propose that the W excess was caused by retention in an Os-Ir alloy phase, whose stability is dependent on fO 2 of the mantle source region. This explanation could help to account for the particularly low W content of N-MORB and implies that the lithophile behaviour of W in basaltic rocks is not an accurate representation of the behaviour in the melt source. These findings then become relevant to the interpretation of W-isotopic data for achondrites, where the fractionation of Hf from W during melting is used to infer the Hf/W of the parent body mantle. This is exemplified by the differentiation chronology of the eucrite parent body (EPB), which has been modeled with a melt source with high Hf/W. By contrast, we explore the alternative scenario with a low mantle Hf/W on the EPB. Using available eucrite literature data, a maximum core segregation age of 1.2 ± 1.2 Myr after the closure of CAIs is calculated with a more prolonged time between core formation and mantle fractionation of ca. 2 Myr. This timeline is consistent with most recent published chronologies of the EPB differentiation based on the 53Mn- 53Cr and 26Al- 26Mg systems.

Babechuk, Michael G.; Kamber, Balz S.; Greig, Alan; Canil, Dante; Kodolányi, János

2010-02-01

140

A bayesian dynamic linear model approach for real-time short-term freeway travel time prediction  

Microsoft Academic Search

This paper presents a Bayesian inference-based dynamic linear model (DLM) to predict online short-term travel time on a freeway stretch. The proposed method considers the predicted freeway travel time as the sum of the median of historical travel times, time-varying random variations in travel time, and a model evolution error, where the median is employed to recognize the primary travel

Xiang Fei; Chung-Cheng Lu; Ke Liu

2011-01-01

141

Filament-Based Atmospheric Dispersion Model to Achieve Short Time-Scale Structure of Odor Plumes.  

National Technical Information Service (NTIS)

This article presents the theoretical motivation, implementation approach, and example validation results for a computationally efficient plume simulation model, designed to replicate both the short-term time signature and long-term exposure statistics of...

J. A. Farrell J. Murlis X. Long W. Li R. Carde

2002-01-01

142

Short note: 4D seismic time differences extracted from pre-stack seismic data  

NASA Astrophysics Data System (ADS)

In time-lapse seismic studies, time difference is an important parameter in determining the distribution of oil and underground water because it provides information about reservoir velocity variation. In this short note, we describe a method to extract time differences from pre-stack seismic data based on the reflection time-distance equation. The time-lapse seismic vertical time differences calculated using this method are accurate and it is not necessary to know the interval velocity.

Li, Lailin; Chen, Zhide; Mu, Yongguang; Chen, Xiaohong

2004-06-01

143

Time-domain imaging of radar targets using ultra-wideband or short pulse radars  

Microsoft Academic Search

The development of viable short-pulse radar system has renewed the interest in time domain imaging performed directly in time-domain with temporally measured signal. Since the short-pulse response of a target provides significant information about the positions and strengths of scattering centers, and if observations are made over a wide range of aspect angle, one might create an image of the

Yingcheng Dai

1997-01-01

144

A wide dynamic range CMOS image sensor with multiple short-time exposures  

Microsoft Academic Search

A wide dynamic range CMOS image sensor based on synthesis of long-time and multiple short-time exposure signals for high image quality in the whole illumination range is proposed. A key technique is a high-speed and high-resolution column-parallel integration type analog-to-digital converter (ADC) with nonlinear slope. A prototype wide dynamic range CMOS image sensor that captures a long-exposure and 3 short-exposure

Masaaki Sasaki; Mitsuhito Mase; Shoji Kawahito; Yoshiaki Tadokoro

2004-01-01

145

Short time-scale radiative transfer in light-emitting porous silicon  

Microsoft Academic Search

In this work, a five level system is proposed to model the short time-scale radiative transfer in light-emitting porous silicon. Equations are derived for the various energy levels. The model is applied to picosecond differential transmission measurements made on porous silicon. A picture of short time-scale carrier dynamics is drawn considering the unique properties of confinement, high surface-to-volume ratio and

M. Cynthia Hipwell; C. L. Tien

1999-01-01

146

A New Method to Evaluate the Short-Time Withstand Current for Air Circuit Breaker  

NASA Astrophysics Data System (ADS)

Short-time withstand current is one of the crucial nominal parameters in air circuit breaker. A numerical method to evaluate the short-time withstand current is proposed. Cylindrical current carrying bridge is introduced to describe the contact spot between movable and fixed contacts. Taking into account the action of ferromagnetic splitter plates, the variation of the conductor properties with temperature and the variation of contact spot radius with the electro-dynamic repulsion force, a transient finite element calculation model is developed by coupling the electromagnetic field and thermal field. The loaded short circuit current is considered as the short-time withstand current once the highest temperature is near to the melting point of the contact material. It demonstrates that the method is useful to evaluate the performance of the air circuit breaker.

Xiang, Honggang; Chen, Degui; Li, Xingwen; Tong, Weixiong

147

SLIM--An Early Work Revisited  

SciTech Connect

An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.

Chao, Alex; /SLAC

2008-07-25

148

Method to modify random matrix theory using short-time behavior in chaotic systems.  

PubMed

We discuss a modification to random matrix theory (RMT) eigenstate statistics that systematically takes into account the nonuniversal short-time behavior of chaotic systems. The method avoids diagonalization of the Hamiltonian, instead requiring only knowledge of short-time dynamics for a chaotic system or ensemble of similar systems. Standard RMT and semiclassical predictions are recovered in the limits of zero Ehrenfest time and infinite Heisenberg time, respectively. As examples, we discuss wave-function autocorrelations and cross correlations and show how the approach leads to a significant improvement in the accuracy for simple chaotic systems where comparison can be made with brute-force diagonalization. PMID:19905169

Smith, A Matthew; Kaplan, Lev

2009-09-01

149

Method to modify random matrix theory using short-time behavior in chaotic systems  

NASA Astrophysics Data System (ADS)

We discuss a modification to random matrix theory (RMT) eigenstate statistics that systematically takes into account the nonuniversal short-time behavior of chaotic systems. The method avoids diagonalization of the Hamiltonian, instead requiring only knowledge of short-time dynamics for a chaotic system or ensemble of similar systems. Standard RMT and semiclassical predictions are recovered in the limits of zero Ehrenfest time and infinite Heisenberg time, respectively. As examples, we discuss wave-function autocorrelations and cross correlations and show how the approach leads to a significant improvement in the accuracy for simple chaotic systems where comparison can be made with brute-force diagonalization.

Smith, A. Matthew; Kaplan, Lev

2009-09-01

150

Integrating random matrix theory predictions with short-time dynamical effects in chaotic systems.  

PubMed

We discuss a modification to random matrix theory eigenstate statistics that systematically takes into account the nonuniversal short-time behavior of chaotic systems. The method avoids diagonalization of the Hamiltonian; instead it requires only knowledge of short-time dynamics for a chaotic system or ensemble of similar systems. Standard random matrix theory and semiclassical predictions are recovered in the limits of zero Ehrenfest time and infinite Heisenberg time, respectively. As examples, we discuss wave-function autocorrelations and cross correlations, and show that significant improvement in accuracy is obtained for simple chaotic systems where comparison can be made with brute-force diagonalization. The accuracy of the method persists even when the short-time dynamics of the system or ensemble is known only in a classical approximation. Further improvement in the rate of convergence is obtained when the method is combined with the correlation function bootstrapping approach introduced previously. PMID:20866714

Smith, A Matthew; Kaplan, Lev

2010-07-01

151

Tracking painted pebbles: Short-term rates of sediment movement on four Mojave Desert piedmont surfaces  

Microsoft Academic Search

To quantify short-term sediment movement rates across Mojave Desert piedmonts, 1600 painted and numbered pebbles were laid out in paired, orthogonal, 20 m lines at 4 sites and resurveyed five times over 2 years and revisited 2 years later. Pebble lines cross shallow (5–15 cm), ephemeral channels and adjacent unconsolidated interfluves, the latter being the dominant landform at all sites.

Lyman P. Persico; Kyle K. Nichols; Paul R. Bierman

2005-01-01

152

Real-time mobile customer short message system design and implementation  

NASA Astrophysics Data System (ADS)

To expand the current mobile phone short message service, and to make the contact between schools, teachers, parents and feedback of the modern school office system more timely and conveniently, designed and developed the Short Message System based on the Linux platform. The state-of-the-art principles and designed proposals in the Short Message System based on the Linux platform are introduced. Finally we propose an optimized secure access authentication method. At present, many schools,vbusinesses and research institutions ratify the promotion and application the messaging system gradually, which has shown benign market prospects.

Han, Qirui; Sun, Fang

153

Apparent stability of GPS monumentation from short-baseline time series  

Microsoft Academic Search

Long-running, short ($\\\\ll$1 km) GPS baselines offer an insight into the accuracy budget of geophysical estimates inferred from GPS coordinate time series. In this paper, we report on analysis of 10 short baselines using data spanning several years and examine deviations from a constant baseline length. Annual signals with amplitude >0.5 mm are evident in various coordinate components at 6

Matt A. King; Simon D. P. Williams

2009-01-01

154

Short-term market timing using the bond–equity yield ratio  

Microsoft Academic Search

This paper takes a new look at the market-timing ability of the bond–equity yield ratio (BEYR). We compare the short-term profitability of a naive strategy based on the extreme values of the BEYR to the short-term profitability of a sophisticated strategy relying on regime switches. In contrast to previous studies, we do not document any major international evidence that these

Pierre Giot; Mikael Petitjean

2009-01-01

155

LTL Generalized Model Checking Revisited  

Microsoft Academic Search

Given a 3-valued abstraction of a program (possibly generated using static program analysis and predicate abstraction) and a te mporal logic formula, generalized model checking (GMC) checks whether there exists a concretiza- tion of that abstraction that satisfies the formula. In this p aper, we revisit gen- eralized model checking for linear time (LTL) properties. First, we show that LTL

Patrice Godefroid; Nir Piterman

2009-01-01

156

Time-dependent Theory of Laser-assisted Auger Decay induced by ultra-short Pulses  

Microsoft Academic Search

A theoretical description of Auger decay induced by ultra-short pulses in the presence of a strong laser field is presented. It is based on a numerical solution of the time-dependent Schrödinger equations describing the Auger process. Appearance of the sidebands and their gross structure are discussed. With the advent of attosecond physics, the time evolution of Auger relaxation processes in

N. M. Kabachnik; A. K. Kazansky

157

Effect of Short Time Heating under Load on the Precipitation Hardening in Commercial Aluminum Alloys.  

National Technical Information Service (NTIS)

The investigations of commercial alloys of Al Cu Mg after short time heating in the temperature range of 150 C to 300 C for times from 1 to 8 min. were carried out by electrical resistance measurement and electron microscopic inspection. Under the conditi...

G. Ziegler K. Welpmann

1973-01-01

158

SENSITIVITY ANALYSIS OF SHORT-TERM TRAVEL TIME PREDICTION MODEL'S PARAMETERS  

Microsoft Academic Search

SUMMARY This paper discusses the optimization of different parameters of a Short-Term Travel Time Prediction model for better performance using traffic detector data. This travel time prediction model involves a number of parameters which affect the prediction in one way or other. These parameters are temporal size of pattern, spatial weight, temporal weight, search window, number of best matched patterns

Masao Kuwahara

159

Instrumental delay calibration for VLBI time comparison via short baseline interferometry.  

NASA Astrophysics Data System (ADS)

The authors have developed a short baseline interferometry (SBI) system with a directly controlled reference frequency for VLBI time comparison. SBI is a kind of portable clock method in order to calibrate the instrumental delay. Instrumental delay is an important factor in determining the accuracy of time-and-frequency comparisons.

Kiuchi, H.; Kaneko, A.; Takahashi, Y.; Yoshino, T.; Hase, H.; Schluter, W.

160

On the non-periodic variations of the Earth's rotation parameter in short time scale  

Microsoft Academic Search

The non-periodic variations in short time scale of the Earth's rotation parameter between Jan. 1980 and July 1981 are analysed. The used materials are the optical observations of the time and latitude of the world, presented by the IPMS. The behaviour of UT1-TAI is very complicated, and contains the oscillations of about 13 days period. Concerning the pole positions x

N. Sekiguchi

1982-01-01

161

A search for short time scale TeV variability in Mkn501  

Microsoft Academic Search

We analyse Whipple TeV gamma-ray data from active states of Mkn501 for short time scale variability using the new Excess Pair Fraction (EPF) method. No evidence is found for significant variability on time scales less than 10 minutes.

Michael Carson; Barry McKernan; Tahir Yaqoob; David Fegan

1999-01-01

162

Short time Fourier analysis of the electromyogram - Fast movements and constant contraction  

NASA Technical Reports Server (NTRS)

Short-time Fourier analysis was applied to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. A portion of the data to be transformed by multiplying the signal by a Hamming window was selected, and then the discrete Fourier transform was computed. Shifting the window along the data record, a new spectrum was computed each 10 ms. The transformed data were displayed in spectograms or 'voiceprints'. This short-time technique made it possible to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMGs during isometric contractions at constant force vary in the short (10-20 ms) term. Short-time spectra from EMGs recorded during rapid movements were much less variable. The windowing technique picked out the typical 'three-burst pattern' in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. The analogy between EMGs and speech signals is extended to argue for future applicability of short-time spectral analysis of EMG.

Hannaford, Blake; Lehman, Steven

1986-01-01

163

25 CFR 26.30 - Does the Job Training Program provide part-time training or short-term training?  

Code of Federal Regulations, 2011 CFR

...Does the Job Training Program provide part-time training or short-term training? 26...Does the Job Training Program provide part-time training or short-term training? Yes, part-time and short-term training are...

2011-04-01

164

Detecting determinism in short time series using a quantified averaged false nearest neighbors approach.  

PubMed

We propose a criterion to detect determinism in short time series. This criterion is based on the estimation of the parameter E2 defined by the averaged false neighbors method for analyzing time series [Cao, Physica D 110, 43 (1997)]. Using surrogate data testing with several chaotic and stochastic simulated time series, we show that the variation coefficient of E2 over a few values of the embedding dimension d defines a suitable statistic to detect determinism in short data sequences. This result holds for a time series generated by a high-dimensional chaotic system such as the Mackey-Glass one. Different decreasing lengths of the time series are included in the numerical experiments for both synthetic and real-world data. We also investigate the robustness of the criterion in the case of deterministic time series corrupted by additive noise. PMID:17930320

Ramdani, Sofiane; Bouchara, Frédéric; Casties, Jean-François

2007-09-01

165

Dispersion curves from short-time molecular dynamics simulation. 1. Diatomic chain results  

SciTech Connect

The multiple signal classification method (MUSIC) for frequency estimation is used to compute the frequency dispersion curves of a diatomic chain from the time-dependent structure factor. In this paper, the authors demonstrate that MUSIC can accurately determine the frequencies from very short time trajectories. MUSIC is also used to show how the frequencies can vary in time, i.e., along a trajectory. The method is ideally suited for analyzing molecular dynamics simulations of large systems.

Noid, D.W.; Broocks, B.T.; Gray, S.K.; Marple, S.L.

1988-06-16

166

Hamiltonian flows, short-time propagators and the quantum Zeno effect  

NASA Astrophysics Data System (ADS)

In a recent paper we have examined the short-time propagator for the Schrödinger equation of a point source. An accurate expression modulo ?t2 for the propagator showed that it was independent of the quantum potential implying that the quantum motion is classical for very short times. In this paper we apply these results to the experiment of Itano, Heinzen, Bollinger and Wineland which demonstrates the quantum Zeno effect in beryllium. We show that the transition is inhibited because the applied continuous wave radiation suppresses the quantum potential necessary for the transition to occur. This shows there is no need to appeal to wave function collapse.

de Gosson, Maurice A.; Hiley, Basil J.

2014-04-01

167

Analysis of array errors and a short-time processor in airborne phased array radars  

Microsoft Academic Search

Array errors are inherent in a realistic phased array radar system. The influence of array errors on the clutter degrees of freedom and the clutter subspace in an airborne phased array radar is analyzed. Based on the presented theoretic results, a method of short-time processing followed by coherent integration is proposed for clutter suppression in airborne phased array radars. It

Qing-Guang Liu; Ying-Ning Peng

1996-01-01

168

APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED BED, GAS/SOLID REACTOR  

EPA Science Inventory

The article describes an apparatus for the exposure of a solid to reactive process gas. he switch makes possible short time exposures (equal to or greater than 0.3 s) in a fixed-bed reactor for kinetic studies of rapid reactions....

169

Effects of feedback on eye typing with a short dwell time  

Microsoft Academic Search

Eye typing provides means of communication especially for people with severe disabilities. Recent research indicates that the type of feedback impacts typing speed, error rate, and the user's need to switch her gaze between the on-screen keyboard and the typed text field. The current study focuses on the issues of feedback when a short dwell time (450 ms vs. 900

Päivi Majaranta; Anne Aula; Kari-Jouko Räihä

2004-01-01

170

Short-Time Creep Behavior of Carbon, Graphite, and Silica Phenolic Composites at Elevated Temperatures.  

National Technical Information Service (NTIS)

Short-time tensile creep behavior of carbon, graphite, and silica phenolics at elevated temperatures was determined for durations up to 40 sec. A plasma arc was used as a heat source, with test temperatures ranging from 1095 to 2760C. The results show app...

A. Ching J. D. Buch

1970-01-01

171

Discrimination between fault and magnetizing inrush current in transformers using short-time correlation transform  

Microsoft Academic Search

A new method to discriminate between internal fault current and inrush current is presented in this paper. A short time correlation function is used to extract the dead angle from the differential current. The effect of CT saturation on inrush current is considered and test results with the data obtained from a prototype device on a dynamic power system model

H. Zhang; J. F. Wen; P. Liu; O. P. Malik

2002-01-01

172

Automatic recognition of ground radar targets based on target RCS and short time spectrum variance  

Microsoft Academic Search

This paper presents a novel feature vector to be used with a robust automatic target recognition (ATR) classifier designed for a ground surveillance radar. A three element feature vector has been used where features are based on radar audio signal of 100 milliseconds duration. The short feature length allows fast real-time implementation of the classifier. Classification is done using a

S. Liaqat; S. A. Khan; M. B. Ihsan; S. Z. Asghar; A. Ejaz; A. I. Bhatti

2011-01-01

173

Development of a Single-Stage, Entrained-Flow, Short-Residence-Time Hydrogasifier. Final Report.  

National Technical Information Service (NTIS)

This report describes work performed to develop a single-stage, entrained-flow, short-residence-time reactor for flash hydrogasification of coal. The unique feature is the application of rocket engine injection/mixing techniques to the rapid mixing and re...

1979-01-01

174

Speech enhancement using a minimum-mean square error short-time spectral amplitude estimator  

Microsoft Academic Search

This paper focuses on the class of speech enhancement systems which capitalize on the major importance of the short-time spectral amplitude (STSA) of the speech signal in its perception. A system which utilizes a minimum mean-square error (MMSE) STSA estimator is proposed and then compared with other widely used systems which are based on Wiener filtering and the \\

Y. Ephraim; D. Malah

1984-01-01

175

Short time-scale \\/less than 2 hour\\/ wind variations observed with the Garchy meteor radar  

Microsoft Academic Search

The good altitude definition and the great abundance of wind data (up to 1200 individual measurements per day) given by the Garchy meteor radar facility yield a good opportunity to study short time-scale motions (periods less than 2 hours) in the 80-100 km altitude region. A statistical study of the differences between zonal wind values measured at close points in

J. L. Fellous; M. Glass

1976-01-01

176

Short time-scale X-ray variability of Active Galactic Nuclei  

Microsoft Academic Search

In this work we investigated the short time-scale variability of NGC 4051 and NGC 4388. A quasi-steady QPO of 3922±17 sec was detected for NGC 4051. For NGC 4388, we investigated the rapid spectral variability with a new “Moving Fit” method for processing of the dynamic X-ray spectra.

Alexander V. Halevin

2004-01-01

177

Geodynamic implications of short time scale changes in the geomagnetic dynamo  

Microsoft Academic Search

The discovery of the geomagnetic jerk of 1969 has again focussed attention on short time scale phenomena in the core. The irregular fluctuations in the length of the day and the excitation of the Chandler wobble have characteristics strongly suggesting 'impulsive' torques on the mantle. These are believed to result from electromagnetic phenomena associated with disturbances in the core dynamo,

S. K. Runcorn

1985-01-01

178

Short time-scale heating of the Earth's mantle by ice-sheet dynamics  

Microsoft Academic Search

We have studied the possibility of short time-scale energy transfer from the ice sheet loading and unloading processes to the Earth's interior via viscous dissipation associated with the transient viscoelastic flow in the mantle. We have focussed on the magnitude of glacially induced deformations and the corresponding shear heating for an ice sheet of the spatial extent of Laurentide region

Ladislav Hanyk; Ctirad Matyska; D. A. Yuen

2005-01-01

179

The effect of short time creep on the resistance of smooth and waffle surface cylindrical casings  

Microsoft Academic Search

Conclusions 1.Under conditions of short time creep the bulging of smooth cylindrical casings subjected to the action of axial compression and internal pressure with a pressure parameter of p>0.5 and circumferential stress greater than 0.5 times the tensile strength of the material is asymmetrical.2.In view of the high sensitivity of the creep process to a change intemperature, nonuniformity in the

L. M. Kurshin; V. K. Belov; V. V. Gusev; V. P. Ermakov; I. F. Larionov

1975-01-01

180

High-voltage and short-rise-time pulse-transformer with amorphous cores  

Microsoft Academic Search

A short rise time pulsed power transformer using cobalt-based amorphous alloy cores, which operates at high voltage (~100 kV) and high repetition rate (~4000 pps), has been developed for application as a pulsed power modulator for copper vapor lasers. An output voltage of more than 80 kV, a rise time of 65 ns and a transformation efficiency of 83% were

N. Kobayashi; N. Aoki; H. Horie; Y. Baba; Y. Sano; H. Kimura; C. Konagal

1997-01-01

181

Membrane bioreactor operation at short solids retention times: performance and biomass characteristics  

Microsoft Academic Search

This study investigated the performance and biomass characteristics of a membrane bioreactor (MBR) and a completely mixed activated sludge (CMAS) system operated at short solids retention times (SRT) ranging from 0.25 to 5d and hydraulic retention times of 3 and 6h. The lab-scale reactors were fed with synthetic wastewater to ensure consistency in feed composition. Results show the MBR was

How Y. Ng; Slawomir W. Hermanowicz

2005-01-01

182

A General Framework for Analyzing Data from Two Short Time-Series Microarray Experiments  

Microsoft Academic Search

We propose a general theoretical framework for analyzing differentially expressed genes and behavior patterns from two homogenous short time-course data. The framework generalizes the recently proposed Hilbert-Schmidt Independence Criterion (HSIC)-based framework adapting it to the time-series scenario by utilizing tensor analysis for data transformation. The proposed framework is effective in yielding criteria that can identify both the differentially expressed genes

Mohak Shah; Jacques Corbeil

2011-01-01

183

Short-time spectral analysis with the conventional and sliding CZT  

Microsoft Academic Search

Two sequential short-time spectral analysis techniques, amenable to nonrecursive filter implementation, are the conventional chirp-z-transform (CZT) realization of the discrete Fourier transform and the sliding CZT realization of the discrete sliding Fourier transform. This paper presents a comparative study of frame rate limitations, windowing, time and frequency resolution, spectral correlation, complexity, and inverse structures for these methods, with particular emphasis

1978-01-01

184

Efficient Iterative Time-Domain Beam Propagation Methods for Ultra Short Pulse Propagation: Analysis and Assessment  

Microsoft Academic Search

The time-domain beam propagation method (TD-BPM) has been implemented and analyzed using several iterative numerical techniques to model the propagation of ultra short pulses in optical structures. The methods depend on one-way non-paraxial time domain propagation that use Pade approximant formulation. Several numerical tests showed that the iterative TD-BPM techniques are very stable and converge using few iterations. From accuracy

Husain M. Masoudi; Mohammad S. Akond

2011-01-01

185

Short time-scale variability of chromospheric CA II in late-type stars  

Microsoft Academic Search

The short time-scale variability of singly ionized calcium chromospheric emission has been investigated in a few late-type stars. Emission-line variations with time scales of a few minutes to hours are seen in Alpha Tau (K5 III), Lambda And (G8 III-IV), and Epsilon Eri (K2 V). The existence of substantial chromospheric flux changes (10 to the 30th to 10 to the

S. L. Baliunas; A. H. Vaughan; L. Hartmann; W. Liller; A. K. Dupree

1981-01-01

186

Short-Time-Scale Thermal Mapping of Microdevices Using a Scanning Thermoreflectance Technique  

Microsoft Academic Search

The performance and reliability of microdevices can be strongly influenced by the peak temperature rise and spatial temperature distribution during brief electrical overstress (EOS) phenomena, which can occur at sub-microseco nd time scales. The present study investigates short-time-scale laser reflectance thermometry of microde­ vices by examining the impact of passivation overlayers on the thermoreflectance signal and by demonstrating a calibration

K. E. Goodson

2008-01-01

187

Short time scale variability at gamma rays in FSRQs and implications on the current models  

Microsoft Academic Search

We studied the rapid variability at GeV gamma rays of the flat-spectrum radio quasar PKS 1222+216, which was recently found by the MAGIC Cerenkov telescope to display very short variability (minutes time scale) at hundreds of GeV. We analyzed the time period between 2010 April 29 and June 20, when the source generated a few gamma-ray flares with flux in

L. Foschini; G. Ghisellini; F. Tavecchio; G. Bonnoli; A. Stamerra

2011-01-01

188

Evaluation and development of models for resuspension of aerosols at short times after deposition  

NASA Astrophysics Data System (ADS)

Resuspension is known to transport hazardous particles in the natural environment, moving a fraction of deposited material back into the atmosphere. This process is notoriously difficult to model, given the complexity of the turbulent boundary layer and chemistry of the three-phase interface (air, liquid, solid) typically found at the land surface. Wind tunnel studies have demonstrated the importance of resuspension within a short time after deposition, but there exists no robust model for short-term resuspension. Numerical simulations of accidental or terrorist releases of hazardous materials need such a model to accurately predict fate and transport of the materials within hours to days after release. Many accepted conventional models were derived from resuspension data for aged sources, such as former weapons test sites; these data sets, and the associated models, may not be appropriate for short-time resuspension. The study described here reexamined historical wind tunnel data on short-term resuspension, with the goal of developing a model appropriate for numerical simulations. Empirical models are derived from these data using a suite of parameters (friction velocity, particle diameter, surface roughness, particle density, and time). These empirical models, and the wind tunnel data, are compared quantitatively with existing conventional models from the literature. The conventional models underpredict short-time resuspension, resulting in order-of-magnitude errors in predictions of resuspended mass. Only three models perform reasonably well: the empirical models derived from the data and an adaptation of the NCRP 129 model. More data are needed to validate the empirical models and build the physical understanding of the processes involved.

Loosmore, Gwen A.

189

Internal dynamics of proteins: short time and long time motions of aromatic sidechains in PTI  

SciTech Connect

Theoretical approaches to the internal dynamics of proteins are outlined and illustrated by application to the aromatic sidechain motions of tyrosines in the bovine pancreatic trypsin inhibitor. High frequency torsional oscillations are obtained from a molecular dynamics simulation, while the longer time ring rotations are analyzed by use of adiabatic energy minimization and special transition-state trajectory techniques.

Karplus, M.; Gelin, B.R.; McCammon, J.A.

1980-10-01

190

Probing ECG-based mental state monitoring on short time segments.  

PubMed

Electrocardiography is used to provide features for mental state monitoring systems. There is a need for quick mental state assessment in some applications such as attentive user interfaces. We analyzed how heart rate and heart rate variability features are influenced by working memory load (WKL) and time-on-task (TOT) on very short time segments (5s) with both statistical significance and classification performance results. It is shown that classification of such mental states can be performed on very short time segments and that heart rate is more predictive of TOT level than heart rate variability. However, both features are efficient for WKL level classification. What's more, interesting interaction effects are uncovered: TOT influences WKL level classification either favorably when based on HR, or adversely when based on HRV. Implications for mental state monitoring are discussed. PMID:24111258

Roy, Raphaelle N; Charbonnier, Sylvie; Campagne, Aurelie

2013-01-01

191

Short time-scale variability of chromospheric Ca II in late-type stars  

NASA Technical Reports Server (NTRS)

The short time-scale variability of singly ionized calcium chromospheric emission has been investigated in a few late-type stars. Emission-line variations with time scales of a few minutes to hours are seen in Alpha Tau (K5 III), Lambda And (G8 III-IV), and Epsilon Eri (K2 V). The existence of substantial chromospheric flux changes (10 to the 30th to 10 to the 32nd ergs) over short periods of time suggests that the calcium emission arises from a few small, coherent regions. Frequencies present in the data are discussed in the context of acoustic wave predictions and estimated acoustic cutoff frequencies for giants and dwarfs.

Baliunas, S. L.; Vaughan, A. H.; Hartmann, L.; Liller, W.; Dupree, A. K.

1981-01-01

192

Difference-based clustering of short time-course microarray data with replicates  

PubMed Central

Background There are some limitations associated with conventional clustering methods for short time-course gene expression data. The current algorithms require prior domain knowledge and do not incorporate information from replicates. Moreover, the results are not always easy to interpret biologically. Results We propose a novel algorithm for identifying a subset of genes sharing a significant temporal expression pattern when replicates are used. Our algorithm requires no prior knowledge, instead relying on an observed statistic which is based on the first and second order differences between adjacent time-points. Here, a pattern is predefined as the sequence of symbols indicating direction and the rate of change between time-points, and each gene is assigned to a cluster whose members share a similar pattern. We evaluated the performance of our algorithm to those of K-means, Self-Organizing Map and the Short Time-series Expression Miner methods. Conclusions Assessments using simulated and real data show that our method outperformed aforementioned algorithms. Our approach is an appropriate solution for clustering short time-course microarray data with replicates.

Kim, Jihoon; Kim, Ju Han

2007-01-01

193

Reliable real-time framework for short-term freeway travel time prediction  

Microsoft Academic Search

It is widely acknowledged that traffic information has the potential\\u000a\\u0009of increasing the reliability in road networks and in alleviating\\u000a\\u0009congestion and its negative environmental and societal side effects.\\u000a\\u0009However, for these beneficial collective effects to occur, reliable\\u000a\\u0009and accurate traffic information is a prerequisite. Building on previous\\u000a\\u0009research, this article presents a reliable framework for online travel\\u000a\\u0009time prediction

J. W. C. van Lint

2006-01-01

194

Estimation of interaction strength and direction from short and noisy time series.  

PubMed

A technique for determination of character and intensity of interaction between the elements of complex systems based on reconstruction of model equations for phase dynamics is extended to the case of short and noisy time series. Corrections, which eliminate systematic errors of the estimates, and expressions for confidence intervals are derived. Analytic results are presented for a particular case of linear uncoupled systems, and their validity for a much wider range of situations is demonstrated with numerical examples. The technique should be useful for the analysis of nonstationary processes in real time, including the situations of significant noise and restrictions on the observation time. PMID:14683037

Smirnov, Dmitry A; Bezruchko, Boris P

2003-10-01

195

Short Lag Times for Invasive Tropical Plants: Evidence from Experimental Plantings in Hawai'i  

PubMed Central

Background The lag time of an invasion is the delay between arrival of an introduced species and its successful spread in a new area. To date, most estimates of lag times for plants have been indirect or anecdotal, and these estimates suggest that plant invasions are often characterized by lag times of 50 years or more. No general estimates are available of lag times for tropical plant invasions. Historical plantings and documentation were used to directly estimate lag times for tropical plant invasions in Hawai'i. Methodology/Principal Findings Historical planting records for the Lyon Arboretum dating back to 1920 were examined to identify plants that have since become invasive pests in the Hawaiian Islands. Annual reports describing escape from plantings were then used to determine the lag times between initial plantings and earliest recorded spread of the successful invaders. Among 23 species that eventually became invasive pests, the average lag time between introduction and first evidence of spread was 14 years for woody plants and 5 years for herbaceous plants. Conclusions/Significance These direct estimates of lag times are as much as an order of magnitude shorter than previous, indirect estimates, which were mainly based on temperate plants. Tropical invaders may have much shorter lag times than temperate species. A lack of direct and deliberate observations may have also inflated many previous lag time estimates. Although there have been documented cases of long lag times due to delayed arrival of a mutualist or environmental changes over time, this study suggests that most successful invasions are likely to begin shortly after arrival of the plant in a suitable habitat, at least in tropical environments. Short lag times suggest that controlled field trials may be a practical element of risk assessment for plant introductions.

Daehler, Curtis C.

2009-01-01

196

Characterization of polydopamine thin films deposited at short times by autoxidation of dopamine.  

PubMed

Current interest in melanin films derived from the autoxidation of dopamine stems from their use as a universal adhesion layer. Here we report chemical and physical characterization of polydopamine films deposited on gold surfaces from stirred basic solutions at times ranging from 2 to 60 min, with a focus on times ?10 min. Data from Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical methods suggest the presence of starting (dopamine) and intermediate (C=N-containing tautomers of quinone and indole) species in the polydopamine films at all deposition times. A uniform overlayer analysis of the XPS data indicates that film thickness increased linearly at short deposition times of ?10 min. At deposition times ?10 min, the films appeared largely continuous with surface roughness ? ? 2 nm, as determined by atomic force microscopy (AFM). Pinhole-free films, as determined by anionic redox probe measurements, required deposition times of 60 min or greater. PMID:23750451

Zangmeister, Rebecca A; Morris, Todd A; Tarlov, Michael J

2013-07-01

197

Short-term foreshocks in Southern California and Italy revisited: Observed deviations from the Epidemic-Type Aftershock Sequence (ETAS) Model  

NASA Astrophysics Data System (ADS)

Numerous studies have suggested that short-term foreshocks observed prior to large earthquakes are undistinguishable from the normal behaviour of seismicity, which is well described for example by the Epidemic-Type Aftershock Sequence (ETAS) model. Here we show that these studies fail to extract abnormal foreshock behaviour due to the much more frequent occurrence of aftershocks in comparison to potential foreshocks, which results in undervaluing the role of foreshocks. We first define mainshocks as earthquakes of magnitude M6+ and use a space-time-magnitude window method with a maximum distance of 10 km to the mainshock, a maximum time range of 3 days before the mainshock and a minimum magnitude M4+ to define foreshocks in Southern California and in Italy. We then compare the observed rate of foreshock-mainshock pairs to the rate expected by ETAS simulations. Similar to previous studies, these results indicate that the foreshock activity observed in real catalogues is compatible with the ETAS model. Definition of foreshocks with a window method is, however, simplistic, since any individual event may be considered a foreshock although it is impossible to distinguish a foreshock from background or aftershock activity at a one-to-one event basis. We extend our foreshock analysis based on the predictions of the Non-Critical Precursory Accelerating Seismicity Theory (NC PAST), which are: (1) foreshocks are due to overloading on the main fault and occur in clusters, the activity of which is significantly higher than background activity, (2) microseismicity (M<3) must be included for the emergence of a reliable signal and (3) foreshocks are not systematic before large earthquakes due to aleatoric uncertainty on the rupture process. Following these guidelines, we systematically investigate foreshock sequences before large earthquakes (M6+) in Southern California and Italy. Using different approaches, we finally show that significant anomalies are observed before some mainshocks (e.g., 1992 Landers, 2009 L'Aquila earthquakes), which are not explained by the ETAS process. Anomalies are defined as any deviation from a Poissonian distribution (which describes the stationary background seismicity) with a Poisson probability lower than 10^-4. We use approaches such as heuristic (what if a large cluster of events is not preceded by any event large enough to produce such a cluster?), ETAS stochastic declustering and a nearest-neighbour cluster technique that differentiates between foreshocks, mainshocks and aftershocks. Our results highlight the shortcomings of current systematic precursory seismicity analyses: First, in order to consider a sufficient number of mainshocks, a large region is usually considered, which requires the use of a relatively high completeness magnitude. This considerably limits the significance of potential anomalies, which are mostly defined from microseismicity (according to the NC PAST). Second, it is commonly assumed that all mainshocks behave the same (in agreement with the ETAS process), which would validate stacking/averaging over multiple sequences. This approach however fails if mainshocks behave differently from one to another (according to the NC PAST). To conclude, microseismicity and non-systematic presence of anomalies are key conditions to better understand potential foreshocks before large earthquakes, their physical origin and their potential role in time-dependent hazard assessment and earthquake prediction.

Seif, Stefanie; Mignan, Arnaud; Wiemer, Stefan

2013-04-01

198

Time domain waveform inversion of short-period p-waves for nuclear explosion source time functions. Technical report  

SciTech Connect

This research investigates the estimation of the source time parameters of underground nuclear explosions from the waveforms of short-period teleseismic P-waves. In the simplest consideration, and when the source yield is unconstrained, there are only three source parameters, two that describe the source time function and one for the delay time of the (p)P phase. There are, of course, indications that the (p)P arrival may not have the same amplitude or shape as the direct P arrival, presumably due to anelastic or nonlinear effects between the shot point and the surface. Thus, we will also consider the effect on the waveforms of a decreased (p)P amplitude. Another parameter which has a significant influence upon the observed waveforms is t (t = travel time/Q(av). Accordingly, the variations in the source parameter estimates due to a varying t will also be addressed.

Ruff, L.J.

1981-01-09

199

Least squares support vector machine for short-term prediction of meteorological time series  

NASA Astrophysics Data System (ADS)

The prediction of meteorological time series plays very important role in several fields. In this paper, an application of least squares support vector machine (LS-SVM) for short-term prediction of meteorological time series (e.g. solar irradiation, air temperature, relative humidity, wind speed, wind direction and pressure) is presented. In order to check the generalization capability of the LS-SVM approach, a K-fold cross-validation and Kolmogorov-Smirnov test have been carried out. A comparison between LS-SVM and different artificial neural network (ANN) architectures (recurrent neural network, multi-layered perceptron, radial basis function and probabilistic neural network) is presented and discussed. The comparison showed that the LS-SVM produced significantly better results than ANN architectures. It also indicates that LS-SVM provides promising results for short-term prediction of meteorological data.

Mellit, A.; Pavan, A. Massi; Benghanem, M.

2013-01-01

200

Magnetic Reversal and Excursion Rates from Short-Time Fluctuations in the Virtual Axial Dipole Moment  

NASA Astrophysics Data System (ADS)

Paleomagnetic observations show that magnetic reversals and excursions coincide with times when the field intensity is low. We explore this connection quantitatively by describing variations in the virtual axial dipole moment (VADM) as a stochastic processes. The stochastic model includes a deterministic component (drift term) and a random component (diffusion term). The diffusion term is intended to represent the influence of convective fluctuations in the core. When the correlation time of convective fluctuations is short compared with the sampling of the VADM, the random component is effectively uncorrelated in time. With the further assumption of Gaussian noise, we can describe the probability density function of the VADM in terms of a Fokker-Planck equation. We use VADM estimates from the PADM2M model of Ziegler et al (2011) to reconstruct the drift and diffusion terms in the Fokker-Planck equation. In detail the drift and diffusion terms are computed from VADM fluctuations over time scales of three to four thousand years. Estimates of the drift term establish the shape of a bistable potential well, whereas the diffusion term is nearly independent of the value of the VADM. We find that the amplitude of the diffusion term sets the transition probability from one stable state to the other within the potential well. When the diffusion term is constrained by short-time fluctuations in the PADM2M model, we predict an average of 1 reversal and 4 excursions per million years. However, a modest 30% increase in the average amplitude of short-time fluctuations yields one reversal every 400 kyr, which is more consistent with the long-term reversal rate. The corresponding rate of excursions is roughly 7 per million year. Doubling the amplitude of short-term fluctuations relative to the value given by PADM2M produces one reversal every 100 kyr, which is probably too frequent to be compatible with the observed record. On the other hand, a 40% decrease in the amplitude of short-time fluctuations is sufficient to explain the Cretaceous superchron.

Buffett, B. A.; Ziegler, L. B.; Constable, C.

2012-12-01

201

Non-Gaussian probability distribution of short time scale magnetic field fluctuations at Terra Nova Bay (Antarctica)  

Microsoft Academic Search

The probability distribution functions (PDFs) of short time scale magnetic field fluctuations have been evaluated for Terra Nova Bay data for the time period December 1993 - January 1994. It is found that short time field fluctuations are not Gaussian distributed during disturbed periods. Moreover, magnetic field fluctuations PDFs are quite similar to solar wind parameters statistical distributions near the

G. Consolini; L. Cafarella; P. de Michelis; M. Candidi; A. Meloni

1997-01-01

202

Microbial community in methanogenic packed-bed reactor successfully operating at short hydraulic retention time.  

PubMed

The microbial community in a thermophilic anaerobic packed-bed reactor, which had been successfully operated to convert acetic and butyric acids to methane at a short hydraulic retention time (from 24 h to 1.9 h), was investigated. Archaea closely related to known methanogens were detected by 16S rRNA gene analyses of the effluents, together with diverse types of unidentified bacteria. PMID:16716930

Sasaki, Kengo; Haruta, Shin; Tatara, Masahiro; Yamazawa, Akira; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

2006-03-01

203

Design of a capacitive-sensor signal processing system with high accuracy and short conversion time  

Microsoft Academic Search

This paper presents the design of a capacitive-sensor signal processing system, which is capable of converting the capacitance change into digital signal output with high accuracy and short conversion time. The system consists the current conveyors, analog switches, current source, A\\/D converter and 32-bit advanced RISC machine (ARM). The digital readout ranges from 0000 to FFFF corresponding to the capacitance

An Sang Hou; Susan Xiao-Ping Su

2005-01-01

204

Effect of Monitoring System Structure on Short-term Prediction of Highway Travel Time  

Microsoft Academic Search

This article discusses how the structure of the measurement system affects the short-term forecasts of travel time based on it. The effects of section length and location of different measurement stations were investigated. The study used empirical data. The research was carried out on a 28-km long interurban two-lane highway section. The prediction models were made as feedforward multilayer perceptron

Satu Innamaa

2006-01-01

205

Direct conversion of methane in formaldehyde at very short residence time  

Microsoft Academic Search

To obtain new kinetic data, a quartz annular flow microreactor was chosen for the experimental investigation of the gas phase partial methane oxidation to formaldehyde under high temperature (1173–1273K) and short residence time (20–60ms). High formaldehyde selectivity (up to 80%) is achieved, but the yield remains low. For a single pass operation, the best HCHO experimental yield is 2.4%. The

J. Zhang; V. Burklé-Vitzthum; P. M. Marquaire; G. Wild; J. M. Commenge

2011-01-01

206

Cyclization of Rouse chains at long- and short-time scales  

Microsoft Academic Search

We have investigated cyclization of a Rouse chain at long and short times by a Langevin dynamics simulation method. We measure S(t), the fraction of nonreacted chains, for polymerizations ranging from Z=5 to Z=800 and capture distances ranging from a=0.1b to a=8b where b is the bond length. Comparison is made with two theoretical approaches. The first is a decoupling

Chuck Yeung; Barry Friedman

2005-01-01

207

Intrinsic dynamics of heart regulatory systems on short time-scales: from experiment to modelling  

Microsoft Academic Search

We discuss open problems related to the stochastic modeling of cardiac\\u000afunction. The work is based on an experimental investigation of the dynamics of\\u000aheart rate variability (HRV) in the absence of respiratory perturbations. We\\u000aconsider first the cardiac control system on short time scales via an analysis\\u000aof HRV within the framework of a random walk approach. Our experiments

I. A. Khovanov; N. A. Khovanova; P. V. E. McClintock; A. Stefanovska

2009-01-01

208

Multiwavelength observations of short time-scale variability in NGC 4151. I. Ultraviolet observations  

Microsoft Academic Search

We present the results of an intensive ultraviolet monitoring campaign on the\\u000aSeyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale\\u000avariability over a broad range in wavelength. The nucleus of NGC 4151 was\\u000aobserved continuously with the {\\\\it International Ultraviolet Explorer} (IUE)\\u000afor 9.3 days, yielding a pair of LWP and SWP spectra

P. M. Rodr ´ õguez-Pascual; S. V. Penton; R. A. Edelson; D. Alloin; T. R. Ayres; J. Clavel; K. Horne; W. N. Johnson; S. Kaspi; K. T. Korista; G. A. Kriss; J. H. Krolik; M. A. Malkan; D. Maoz; H. Netzer; P. T. O'Brien; B. M. Peterson; G. A. Reichert; J. M. Shull; M.-H. Ulrich; W. Wamsteker; R. S. Warwick; T. Yaqoob; T. J. Balonek; P. Barr; G. E. Bromage; M. Carini; T. E. Carone

1996-01-01

209

Quantifying particle dispersal in aquatic sediments at short time scales: model selection  

Microsoft Academic Search

In a pulse-tracer experiment, a layer of tracer particles is added to the sediment-water interface, and the down-mixing of these particles is followed over a short time scale. Here, we compare different models (biodiffusion, telegraph, CTRW) to analyse the resulting tracer depth profiles. The biodiffusion model is widely applied, but has two problems associated: (1) infinite propagation speed: the infinitely

F. J. R. Meysman; V. Malyuga; B. P. Boudreau; J. J. Middelburg

2008-01-01

210

Short-time-scale features of the Earth’s polar motion  

Microsoft Academic Search

The fundamental astrometric problem of high-accuracy interpolation and forecasting of the Earth’s polar motion on short time\\u000a scales from 1–2 to 10–30 days is studied. Hierarchies of interval length and parameter accuracy are established using appropriate\\u000a models for the process. Filtering algorithms are adjusted using a weighted least squares fit of measurements of the International\\u000a Earth Rotation Service (IERS). Best-fit

L. D. Akulenko; Yu. G. Markov; V. V. Perepelkin; L. V. Rykhlova

2009-01-01

211

Multi-Wavelength Study of Sgr A*: The Short Time Scale Variability  

Microsoft Academic Search

To understand the correlation and the radiation mechanism of flare emission in different wavelength bands, we have coordinated a number of telescopes to observe Sgr A* simultaneously. We focus only one aspect of the preliminary results of our multi-wavelength observing campaigns, namely, the short time scale variability of emission from Sgr A* in near-IR, X-ray and radio wavelengths. The structure

F. Yusef-Zadeh; J. Miller-Jones; D. Roberts; M. Wardle; M. Reid; K. Dodds-Eden; D. Porquet; N. Grosso

2011-01-01

212

THE DUAL BEAM PICOSECOND CONTINUUM TECHNIQUE FOR MEASUREMENT OF SHORT-TIME-SCALE TRANSMISSION SPECTRA  

Microsoft Academic Search

In this work, a dual-beam measurement technique is presented to measure the short-time-scale optical properties of novel materials. It is shown that the picosecond continuum probe source obtained from nonlinear interaction with H2O\\/D2O is highly variable and does not permit detection of small changes in absorption \\/transmission spectra. The dual-beam approach is proposed to allow simultaneous measurement of a sample's

M. Cynthia Hipwell; Chang-Lin Tien; Xianglei Mao; Richard E. Russo

1998-01-01

213

Short contact time thermal cracking of carbonaceous wastes to alpha olefins  

Microsoft Academic Search

A continuous short contact time thermal cracker was constructed and operated to investigate the production of alpha olefins in the C9–C16 range. Alpha olefins in this range are normally used as chemical feedstocks for lubricants, surfactants, alcohols and other valuable commodities. The CETC unit was operated at 100 g h?1 between 495 and 570°C using paraffin wax, waste wax from

Michio Ikura; Maria Stanciulescu; James F Kelly

1999-01-01

214

Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres  

NASA Astrophysics Data System (ADS)

We present a detailed study of short-time dynamic properties in concentrated suspensions of charge-stabilized and of neutral colloidal spheres. The particles in many of these systems are subject to significant many-body hydrodynamic interactions. A recently developed accelerated Stokesian dynamics (ASD) simulation method is used to calculate hydrodynamic functions, wave-number-dependent collective diffusion coefficients, self-diffusion and sedimentation coefficients, and high-frequency limiting viscosities. The dynamic properties are discussed in dependence on the particle concentration and salt content. Our ASD simulation results are compared with existing theoretical predictions, notably those of the renormalized density fluctuation expansion method of Beenakker and Mazur [Physica A 126, 349 (1984)], and earlier simulation data on hard spheres. The range of applicability and the accuracy of various theoretical expressions for short-time properties are explored through comparison with the simulation data. We analyze, in particular, the validity of generalized Stokes-Einstein relations relating short-time diffusion properties to the high-frequency limiting viscosity, and we point to the distinctly different behavior of de-ionized charge-stabilized systems in comparison to hard spheres.

Banchio, Adolfo J.; Nägele, Gerhard

2008-03-01

215

An analytic algorithm for global coverage of the revisiting orbit and its application to the CFOSAT satellite  

NASA Astrophysics Data System (ADS)

This paper addresses a new analytic algorithm for global coverage of the revisiting orbit and its application to the mission revisiting the Earth within long periods of time, such as Chinese-French Oceanic Satellite (abbr., CFOSAT). In the first, it is presented that the traditional design methodology of the revisiting orbit for some imaging satellites only on the single (ascending or descending) pass, and the repeating orbit is employed to perform the global coverage within short periods of time. However, the selection of the repeating orbit is essentially to yield the suboptimum from the rare measure of rational numbers of passes per day, which will lose lots of available revisiting orbits. Thus, an innovative design scheme is proposed to check both rational and irrational passes per day to acquire the relationship between the coverage percentage and the altitude. To improve the traditional imaging only on the single pass, the proposed algorithm is mapping every pass into its ascending and descending nodes on the specified latitude circle, and then is accumulating the projected width on the circle by the field of view of the satellite. The ergodic geometry of coverage percentage produced from the algorithm is affecting the final scheme, such as the optimal one owning the largest percentage, and the balance one possessing the less gradient in its vicinity, and is guiding to heuristic design for the station-keeping control strategies. The application of CFOSAT validates the feasibility of the algorithm.

Xu, Ming; Huang, Li

2014-04-01

216

Examining the effects of variability in short time scale demands on solute transport.  

SciTech Connect

Variations in water use at short time scales, seconds to minutes, produce variation in transport of solutes through a water supply network. However, the degree to which short term variations in demand influence the solute concentrations at different locations in the network is poorly understood. Here we examine the effect of variability in demand on advective transport of a conservative solute (e.g. chloride) through a water supply network by defining the demand at each node in the model as a stochastic process. The stochastic demands are generated using a Poisson rectangular pulse (PRP) model for the case of a dead-end water line serving 20 homes represented as a single node. The simple dead-end network model is used to examine the variation in Reynolds number, the proportion of time that there is no flow (i.e., stagnant conditions, in the pipe) and the travel time defined as the time for cumulative demand to equal the volume of water in 1000 feet of pipe. Changes in these performance measures are examined as the fine scale demand functions are aggregated over larger and larger time scales. Results are compared to previously developed analytical expressions for the first and second moments of these three performance measures. A new approach to predict the reduction in variance of the performance measures based on perturbation theory is presented and compared to the results of the numerical simulations. The distribution of travel time is relatively consistent across time scales until the time step approaches that of the travel time. However, the proportion of stagnant flow periods decreases rapidly as the simulation time step increases. Both sets of analytical expressions are capable of providing adequate, first-order predictions of the simulation results.

Tidwell, Vincent Carroll; Buchberger, Steven G. (University of Cincinnati, Cincinnati, OH); McKenna, Sean Andrew

2003-01-01

217

Short time ion pulse extraction from the Dresden electron beam ion trap.  

PubMed

We present measurements of the extraction of short time pulses of highly charged ions (4 keV, Ar(16+)) from the Dresden electron beam ion trap. Thereby the dependence of the extractable ionic charge on the extraction regime was investigated. The ion extraction time was varied between 20 ns and 1 micros. Furthermore the production of carbon ions and the influence of the extraction regime on the pulse widths was investigated to obtain information about the suitability of the Dresden EBIS-A in synchrotron based particle therapy facilities. PMID:20192362

Kentsch, U; Zschornack, G; Schwan, A; Ullmann, F

2010-02-01

218

Fast converging path integrals for time-dependent potentials: I. Recursive calculation of short-time expansion of the propagator  

NASA Astrophysics Data System (ADS)

In this and the subsequent paper (Balaž et al 2011 J. Stat. Mech. P03005) we develop a recursive approach for calculating the short-time expansion of the propagator for a general quantum system in a time-dependent potential to orders that have not been accessible before. To this end the propagator is expressed in terms of a discretized effective potential, for which we derive and analytically solve a set of efficient recursion relations. Such a discretized effective potential can be used to substantially speed up numerical Monte Carlo simulations for path integrals, or to set up various analytic approximation techniques to study properties of quantum systems in time-dependent potentials. The analytically derived results are numerically verified by treating several simple models.

Balaž, Antun; Vidanovi?, Ivana; Bogojevi?, Aleksandar; Beli?, Aleksandar; Pelster, Axel

2011-03-01

219

LTL generalized model checking revisited  

Microsoft Academic Search

Given a 3-valued abstraction of a program (possibly generated using static program analysis and predicate abstraction) and\\u000a a temporal logic formula, generalized model checking (GMC) checks whether there exists a concretization of that abstraction\\u000a that satisfies the formula. In this paper, we revisit generalized model checking for linear time (LTL) properties. First,\\u000a we show that LTL GMC is 2EXPTIME-complete in

Patrice Godefroid; Nir Piterman

2008-01-01

220

Use of extremely short Förster resonance energy transfer probes in real-time polymerase chain reaction.  

PubMed

Described in the article is a new approach for the sequence-specific detection of nucleic acids in real-time polymerase chain reaction (PCR) using fluorescently labeled oligonucleotide probes. The method is based on the production of PCR amplicons, which fold into dumbbell-like secondary structures carrying a specially designed 'probe-luring' sequence at their 5' ends. Hybridization of this sequence to a complementary 'anchoring' tail introduced at the 3' end of a fluorescent probe enables the probe to bind to its target during PCR, and the subsequent probe cleavage results in the florescence signal. As it has been shown in the study, this amplicon-endorsed and guided formation of the probe-target duplex allows the use of extremely short oligonucleotide probes, up to tetranucleotides in length. In particular, the short length of the fluorescent probes makes possible the development of a 'universal' probe inventory that is relatively small in size but represents all possible sequence variations. The unparalleled cost-effectiveness of the inventory approach is discussed. Despite the short length of the probes, this new method, named Angler real-time PCR, remains highly sequence specific, and the results of the study indicate that it can be effectively used for quantitative PCR and the detection of polymorphic variations. PMID:24013564

Kutyavin, Igor V

2013-11-01

221

decays revisited  

NASA Astrophysics Data System (ADS)

We revisit the determination of ? S (m {/? 2}) using a fit to inclusive ? hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K 4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e- annihilation cross sections, which decrease the uncertainty in the separation of vector and axial-vector spectral functions, and (3) improved results from BABAR and Belle on ? branching fractions involving kaons. We estimate that the fourth-order perturbative prediction reduces the theoretical uncertainty, introduced by the truncation of the series, by 20% with respect to earlier determinations. We discuss to some detail the perturbative prediction of two different methods: fixed-order perturbation theory (FOPT) and contour-improved perturbative theory (CIPT). The corresponding theoretical uncertainties are studied at the ? and Z mass scales. The CIPT method is found to be more stable with respect to the missing higher order contributions and to renormalization scale variations. It is also shown that FOPT suffers from convergence problems along the complex integration contour. Nonperturbative contributions extracted from the most inclusive fit are small, in agreement with earlier determinations. Systematic effects from quark-hadron duality violation are estimated with simple models and found to be within the quoted systematic errors. The fit based on CIPT gives ? S (m {/? 2})=0.344±0.005±0.007, where the first error is experimental and the second theoretical. After evolution to M Z we obtain ? S (M {/Z 2})=0.1212±0.0005±0.0008±0.0005, where the errors are respectively experimental, theoretical and due to the evolution. The result is in agreement with the corresponding N3LO value derived from essentially the Z width in the global electroweak fit. The ? S (M {/Z 2}) determination from ? decays is the most precise one to date.

Davier, M.; Descotes-Genon, S.; Höcker, A.; Malaescu, B.; Zhang, Z.

2008-08-01

222

Rotational-oscillatory variations in the Earth rotation parameters within short time intervals  

NASA Astrophysics Data System (ADS)

A mathematical model for rotational-oscillatory motions of the Earth is constructed by applying celestial mechanics to the spatial problem of the Earth-Moon system subject to the Sun's gravitation. Some basic phenomena associated with tidal irregularity in the Earth's axial rotation and the polar oscillations are studied. It is shown that the perturbing component of the gravitational-tidal forces orthogonal to the plane of the lunar orbit is responsible for some short-term perturbations in the Moon's motion. The constructed model for the rotational-oscillatory motions of the deformable Earth includes both the main high-amplitude perturbations and more complex small-scale motions attributed to short-term lunar perturbations with combinational frequencies. Numerical modeling (interpolation and forecasting) of the Earth rotation parameters within various time intervals based on astrometric data obtained by the International Earth Rotation Service is presented.

Akulenko, L. D.; Markov, Yu. G.; Perepelkin, V. V.; Rykhlova, L. V.; Filippova, A. S.

2013-05-01

223

Nonlinear response of vessel walls due to short-time thermomechanical loading  

SciTech Connect

Maintaining structural integrity of the reactor pressure vessel (RPV) during a postulated core melt accident is an important safety consideration in the design of the vessel. This study addresses the failure predictions of the vessel due to thermal and pressure loadings fro the molten core debris depositing on the lower head of the vessel. Different loading combinations were considered based on the dead load, yield stress assumptions, material response and internal pressurization. The analyses considered only short term failure (quasi static) modes, long term failure modes were not considered. Short term failure modes include plastic instabilities of the structure and failure due to exceeding the failure strain. Long term failure odes would be caused by creep rupture that leads to plastic instability of the structure. Due to the sort time durations analyzed, creep was not considered in the analyses presented.

Pfeiffer, P.A.; Kulak, R.F.

1994-06-01

224

Short-term cost for long-term benefit: time preference and cancer control.  

PubMed

A tradeoff between short-term costs and long-term gains characterizes many cancer control behaviors, such as behavior change (e.g., quitting smoking), screening (e.g., mammography), and prevention (e.g., healthy diet). One factor that may influence these tradeoffs is time preference, or the value assigned to future outcomes relative to immediate ones. Studies of the relationship between individual differences in time preference and preventive health behaviors, however, have yielded mixed results. Time preference is related to addictive behaviors (e.g., smoking) but not to other preventive health behaviors (e.g., vaccination). This pattern of results suggests that time preference measures reflect an ability to forgo immediate gratification that is applicable to hot behaviors, such as smoking, but not to cold behaviors, such as vaccination. PMID:16045418

Chapman, Gretchen B

2005-07-01

225

Short-term memory loss over time without retroactive stimulus interference.  

PubMed

A key question in cognitive psychology is whether information in short-term memory is lost as a function of time. Lewandowsky, Duncan, and Brown (2004) argued against that memory loss because forgetting in serial recall occurred to the same extent across serial positions regardless of the rate of recall. However, we believe Lewandowsky et al. (2004) only prevented one of two types of rehearsal; they did not prevent nonarticulatory rehearsal via attention. To prevent articulatory and nonarticulatory rehearsal without introducing interference, we presented unevenly timed stimuli for serial recall and, on some trials, required that the timing of stimuli be reproduced in the response. In those trials only, evidence of memory loss over time emerged. Further research is needed to identify whether this memory loss is decay or lost distinctiveness. PMID:18605508

Cowan, Nelson; AuBuchon, Angela M

2008-02-01

226

Ordering and short-time orientational diffusion in dipolar hard-spherical colloids  

NASA Astrophysics Data System (ADS)

Orientational hydrodynamic functions and short-time, self-orientational and collective orientational diffusion coefficients of dipolar hard-spherical colloids are performed on a homogeneous isotropic phase, as functions of the wave vector q, for various values of the volume fraction and the dipolar strength of the macroparticles. The calculation is based on the dynamic orientational structure factor, which is the time-dependent self-correlation of the orientation density. We assume that the time evolution of the orientation density is given by the Smoluchoswki's equation, taking into account the hydrodynamic interactions as well as the dipolar interaction. The former are considered assuming pairwise additivity. The importance of the dynamic orientational structure factor is that its initial slope can be measured in a depolarized light scattering experiment. The results predict a different behavior for dilute and for dense dipolar colloids. The ordering phenomena are studied via the ordering coefficients, which are the orientational hydrodynamic functions at q=0. The results show that as the dipolar colloid evolves to the instability line, the translational ordering velocity increases while the rotational one reduces. The short-time orientational diffusion coefficients at q=0 are also performed. They predict that near to the instability line, the dipolar colloid diffuses translationally more than rotationally. At very dilute concentration the dipolar colloid presents an unexpected dynamical behavior, which seems to indicate that the colloid could be evolving to a reentrant phase.

Alarcón-Waess, O.; Diaz-Herrera, E.

2002-03-01

227

Short time spreading and wetting of offset printing liquids on model calcium carbonate coating structures.  

PubMed

Spreading of oils and water on porous and pre-saturated model carbonate coating structures was studied with high speed video imaging. The short-time data were complemented with long time absorption and wicking experiments. The results indicate a strong dependence between surface structural features of the pigment tablets and water spreading at short times, both in non-saturated and water pre-saturated cases, while the oil spreading is mainly dependent on the liquid properties. Sodium polyacrylate dispersant on pigment surfaces is shown to contribute to water spreading and absorption. On pre-saturated structures the liquid-liquid interactions are dominant and the majority of results support spreading according to the molecular kinetic model. The evidence supports the hypothesis of S. Rousu, P. Gane, and D. Eklund, ["Influence of coating pigment chemistry and morphology on the chromatographic separation of offset ink constituents," in The Science of Papermaking Transactions of the 12th Fundamental Research Symposium, FRC The Pulp & Paper Fundamental Research Society, Oxford, UK, 2001, p. 1115] that at long times the oils absorb into the porous structure at a rate proportional to the ratio of viscosity and surface tension, provided there is no sorptive action with the binder. A combination of nanosized pores and large surface area is useful for providing sufficient absorption capability for carbonate based coatings. PMID:22196346

Koivula, Hanna; Toivakka, Martti; Gane, Patrick

2012-03-01

228

Curvaton dynamics revisited  

NASA Astrophysics Data System (ADS)

We revisit the dynamics of the curvaton in detail taking account of effects from thermal environment, effective potential and decay/dissipation rate for general field values and couplings. We also consider the curvature perturbation generated through combinations of various effects: large scale modulation of the oscillation epoch, the effective dissipation rate and the timing at which the equation of state changes. In particular, we find that it tends to be difficult to explain the observed curvature perturbation by the curvaton mechanism without producing too large non-Gaussianity if the curvaton energy density is dissipated through thermal effects. In particular, we find that if the renormalizable coupling between the curvaton and light elements is larger than the critical value ~ (mphi/Mpl)1/2, the curvaton is soon dissipated away almost regardless of its initial energy density, contrary to the standard perturbative decay. Therefore, the interaction between them should be suppressed in order for the curvaton to survive the thermal dissipation.

Mukaida, Kyohei; Nakayama, Kazunori; Takimoto, Masahiro

2014-06-01

229

The application of phase rotation for localized in Vivo proton spectroscopy with short echo times  

NASA Astrophysics Data System (ADS)

Single voxel localization techniques like STEAM or PRESS lead to the generation of unwanted signals, which must be destroyed by spoiling gradients. The duration of these gradients and the eddy currents they produce lead to comparatively long echo times on standard whole-body systems. This paper reports a way to observe the proper spectrum in the presence of large spurious signals. The method uses a phase-cycling scheme which separates all different signal contributions by two-dimensional Fourier transformation. Localized proton spectra from the human brain with echo times of 20 ms using the PRESS localization technique could be acquired on a 2 T whole-body system. Metabolites with short T2 relaxation times like glutamate or inositol are observed.

Hennig, J.

230

Thick-target bremsstrahlung interpretation of short time-scale solar hard X-ray features  

NASA Technical Reports Server (NTRS)

Steady-state analyses of bremsstrahlung hard X-ray production in solar flares are appropriate only if the lifetime of the high energy electrons in the X-ray source is much shorter than the duration of the observed X-ray burst. For a thick-target nonthermal model, this implies that a full time-dependent analysis is required when the duration of the burst is comparable to the collisional lifetime of the injected electrons, in turn set by the lengths and densities of the flaring region. In this paper we present the results of such a time-dependent analysis, and we point out that the intrinsic temporal signature of the thick-target production mechanism, caused by the finite travel time of the electrons through the target, may indeed rule out such a mechanism for extremely short duration hard X-ray events.

Emslie, A. G.

1983-01-01

231

Short-time behavior of advecting-diffusing scalar fields in Stokes flows  

NASA Astrophysics Data System (ADS)

This article addresses the short-term decay of advecting-diffusing scalar fields in Stokes flows. The analysis is developed in two main subparts. In the first part, we present an analytic approach for a class of simple flow systems expressed mathematically by the one-dimensional advection-diffusion equation w(y)???=??y2?+iV(y)?-?'?, where ? is either time or axial coordinate and iV(y) an imaginary potential. This class of systems encompasses both open- and closed-flow models and corresponds to the dynamics of a single Fourier mode in parallel flows. We derive an analytic expression for the short-time (short-length) decay of ?, and show that this decay is characterized by a universal behavior that depends solely on the singularity of the ratio of the transverse-to-axial velocity components Veff(y)=V(y)/w(y), corresponding to the effective potential in the imaginary potential formulation. If Veff(y) is smooth, then ||?||L2(?)=exp(-?'?-b?3), where b>0 is a constant. Conversely, if the effective potential is singular, then ||?||L2(?)=1-a?? with a>0. The exponent ? attains the value (5)/(3) at the very early stages of the process, while for intermediate stages its value is (3)/(5). By summing over all of the Fourier modes, a stretched exponential decay is obtained in the presence of nonimpulsive initial conditions, while impulsive conditions give rise to an early-stage power-law behavior. In the second part, we consider generic, chaotic, and nonchaotic autonomous Stokes flows, providing a kinematic interpretation of the results found in the first part. The kinematic approach grounded on the warped-time transformation complements the analytical theory developed in the first part.

Giona, M.; Anderson, P. D.; Garofalo, F.

2013-06-01

232

Magnetic Reconnection Sites Observed by the Cluster Spacecraft: Measurement of Short time scale electron effects  

NASA Astrophysics Data System (ADS)

Several events have been observed by the Cluster spacecraft passing close to magnetic reconnection sites in the tail and magnetopause when the fleet configuration is at short spatial scale (spacecraft separation approximately 100 km). These events are studied in the context of corresponding short time scale electron behaviour which contribute to and result from the reconnection process. This is done primarily using Particle Correlator data from the DWP instruments on Cluster in conjunction with other data sets. The particle correlators use captured time series of electron particle counts accumulated in 12 microsecond time bins measured over the energy range of the PEACE HEEA sensor (40 eV to 26 KeV) and on which an auto-correlation is performed. The phenomena studied concerns beam properties, electron acceleration, interaction with waves and any indications of the electron diffusion processes that are occurring. These phenomena are quantified using measures of the strength of particle-particle interactions (general second order statistics on the electrons) and the Index of Dispersion (variance to mean ratio) indicating bunching or scattering processes.

Buckley, A. M.; Carozzi, T. C.; Gough, M. P.; Chambers, E. C.

233

Extraction of self-diffusivity in systems with nondiffusive short-time behavior.  

PubMed

We consider a toy model that captures the short-time nondiffusive behavior seen in many physical systems, to study the extraction of self-diffusivity from particle trajectories. We propose and evaluate a simple method to automatically detect the transition to diffusive behavior. We simulate the toy model to generate data sets of varying quality and test different methods of extracting the self-diffusion coefficient and characterizing its uncertainty. We find that weighted least-squares with statistical bootstrap is the most accurate and efficient means for analyzing the trajectory data. The analysis suggests an iterative recipe for designing simulations to conform to a specified level of accuracy. PMID:24229234

Shanbhag, Sachin

2013-10-01

234

Extraction of self-diffusivity in systems with nondiffusive short-time behavior  

NASA Astrophysics Data System (ADS)

We consider a toy model that captures the short-time nondiffusive behavior seen in many physical systems, to study the extraction of self-diffusivity from particle trajectories. We propose and evaluate a simple method to automatically detect the transition to diffusive behavior. We simulate the toy model to generate data sets of varying quality and test different methods of extracting the self-diffusion coefficient and characterizing its uncertainty. We find that weighted least-squares with statistical bootstrap is the most accurate and efficient means for analyzing the trajectory data. The analysis suggests an iterative recipe for designing simulations to conform to a specified level of accuracy.

Shanbhag, Sachin

2013-10-01

235

Multi-Wavelength Study of Sgr A*: The Short Time Scale Variability  

Microsoft Academic Search

To understand the correlation and the radiation mechanism of flare emission\\u000ain different wavelength bands, we have coordinated a number of telescopes to\\u000aobserve SgrA* simultaneously. We focus only on one aspect of the preliminary\\u000aresults of our multi-wavelength observing campaigns, namely, the short time\\u000ascale variability of emission from SgrA* in near-IR, X-ray and radio\\u000awavelengths. The structure function

F. Yusef-Zadeh; J. Miller-Jones; D. Roberts; M. Wardle; M. Reid; K. Dodds-Eden; D. Porquet; N. Grosso

2010-01-01

236

Mining biological information from 3D short time-series gene expression data: the OPTricluster algorithm  

PubMed Central

Background Nowadays, it is possible to collect expression levels of a set of genes from a set of biological samples during a series of time points. Such data have three dimensions: gene-sample-time (GST). Thus they are called 3D microarray gene expression data. To take advantage of the 3D data collected, and to fully understand the biological knowledge hidden in the GST data, novel subspace clustering algorithms have to be developed to effectively address the biological problem in the corresponding space. Results We developed a subspace clustering algorithm called Order Preserving Triclustering (OPTricluster), for 3D short time-series data mining. OPTricluster is able to identify 3D clusters with coherent evolution from a given 3D dataset using a combinatorial approach on the sample dimension, and the order preserving (OP) concept on the time dimension. The fusion of the two methodologies allows one to study similarities and differences between samples in terms of their temporal expression profile. OPTricluster has been successfully applied to four case studies: immune response in mice infected by malaria (Plasmodium chabaudi), systemic acquired resistance in Arabidopsis thaliana, similarities and differences between inner and outer cotyledon in Brassica napus during seed development, and to Brassica napus whole seed development. These studies showed that OPTricluster is robust to noise and is able to detect the similarities and differences between biological samples. Conclusions Our analysis showed that OPTricluster generally outperforms other well known clustering algorithms such as the TRICLUSTER, gTRICLUSTER and K-means; it is robust to noise and can effectively mine the biological knowledge hidden in the 3D short time-series gene expression data.

2012-01-01

237

How do young children's spatio-symbolic skills change over short time scales?  

PubMed

Three experiments were designed to examine how experience affects young children's spatio-symbolic skills over short time scales. Spatio-symbolic reasoning refers to the ability to interpret and use spatial relations, such as those encountered on a map, to solve symbolic tasks. We designed three tasks in which the featural and spatial correspondences between a map and its referent (a model) were systematically manipulated using a map-model paradigm. We explored how 2.5- to 5-year-olds learn to map spatial arrays when both identical and unique correspondences coexist (Experiment 1), when featural cues are absent (Experiment 2), and when object and location similarities are contradictory, thereby making both featural and spatial mapping strategies distinct (Experiment 3). Although younger children have a stronger tendency to focus on object (or featural) cues, even 2.5-year-olds can appreciate a symbol beyond the level of object similarity. With age, children are increasingly capable of learning to use spatio-relational mapping and of discovering a spatio-symbolic mapping strategy to solve more challenging map use tasks over short time scales. PMID:21855893

Tsubota, Yoko; Chen, Zhe

2012-01-01

238

RBF Neural Network and ANFIS-Based Short-Term Load Forecasting Approach in Real-Time Price Environment  

Microsoft Academic Search

With the appearance of electricity markets, the variation of the price of electricity will influence usage custom of electric energy. This will complicate short-term load forecasting and challenge the existing forecasting methods that are applied to a fixed-price environment. In regard to the influence of real-time electricity prices on short-term load, a model to forecast short-term load is established by

Zhang Yun; Zhou Quan; Sun Caixin; Lei Shaolan; Liu Yuming; Song Yang

2008-01-01

239

Distribution of interspike intervals estimated from multiple spike trains observed in a short time window.  

PubMed

Several nonparametric estimators of the probability distribution of interspike intervals are introduced. The methods are suitable for simultaneous spike trains observed in a time window of length comparable with the mean interspike interval. This reflects the situation in which a high number of input spike trains converge to a single cortical neuron that has to react in a relatively short time. The simulation study is performed to compare the estimators. For that purpose, several types of stationary point processes are considered as the models of neuronal activity. The methods permit one to estimate the distribution of interspike intervals even if practically none of them are observed. The Kaplan-Meier estimator seems to be the most flexible and reliable among all studied methods, but no direct conclusions as to how real neurons work can be deduced from it. PMID:21405716

Pawlas, Zbyn?k; Lansky, Petr

2011-01-01

240

Independent component analysis of short-time Fourier transforms for spontaneous EEG/MEG analysis.  

PubMed

Analysis of spontaneous EEG/MEG needs unsupervised learning methods. While independent component analysis (ICA) has been successfully applied on spontaneous fMRI, it seems to be too sensitive to technical artifacts in EEG/MEG. We propose to apply ICA on short-time Fourier transforms of EEG/MEG signals, in order to find more "interesting" sources than with time-domain ICA, and to more meaningfully sort the obtained components. The method is especially useful for finding sources of rhythmic activity. Furthermore, we propose to use a complex mixing matrix to model sources which are spatially extended and have different phases in different EEG/MEG channels. Simulations with artificial data and experiments on resting-state MEG demonstrate the utility of the method. PMID:19699307

Hyvärinen, Aapo; Ramkumar, Pavan; Parkkonen, Lauri; Hari, Riitta

2010-01-01

241

Characterization of nitrifying microbial community in a submerged membrane bioreactor at short solids retention times.  

PubMed

This study investigated the nitrifying bacterial community in membrane bioreactor (MBR) at short solids retention times (SRTs) of 3, 5 and 10 days. The denaturing gradient gel electrophoresis results showed that different types of ammonia-oxidizing bacteria (AOB) can survive at different operating conditions. The diversity of AOB increased as the SRT increased. The real-time PCR results showed that the amoA gene concentrations were similar when MBRs were stabilized, and it can be a good indicator of stabilized nitrification. The results of clone library indicated that Nitrosomonas was the dominant group of AOB in three reactors. The microarray results showed that Nitrospira was the dominant group of nitrite-oxidizing bacteria (NOB) in the system. All groups of AOB and NOB except Nitrosolobus and Nitrococcus were found in MBR, indicated that the nitrifying bacterial community structure was more complicated. The combination of some molecular tools can provide more information of microbial communities. PMID:24099975

Duan, Liang; Song, Yonghui; Xia, Siqing; Hermanowicz, Slawomir W

2013-12-01

242

EXPLORING THE POTENTIAL OF SHORT-TIME FOURIER TRANSFORMS FOR ANALYZING SKIN CONDUCTANCE AND PUPILLOMETRY IN REAL-TIME APPLICATIONS  

SciTech Connect

The development of real-time predictors of mental workload is critical for the practical application of augmented cognition to human-machine systems. This paper explores a novel method based on a short-time Fourier transform (STFT) for analyzing galvanic skin conductance (SC) and pupillometry time-series data to extract estimates of mental workload with temporal bandwidth high-enough to be useful for augmented cognition applications. We tested the method in the context of a process control task based on the DURESS simulation developed by Vincente and Pawlak (1994; ported to Java by Cosentino,& Ross, 1999). SC, pupil dilation, blink rate, and visual scanning patterns were measured for four participants actively engaged in controlling the simulation. Fault events were introduced that required participants to diagnose errors and make control adjustments to keep the simulator operating within a target range. We were interested in whether the STFT of these measures would produce visible effects of the increase in mental workload and stress associated with these events. Graphical exploratory data analysis of the STFT showed visible increases in the power spectrum across a range of frequencies directly following fault events. We believe this approach shows potential as a relatively unobtrusive, low-cost, high bandwidth measure of mental workload that could be particularly useful for the application of augmented cognition to human-machine systems.

Roger Lew; Brian P. Dyre; Steffen Werner; Jeffrey C. Joe; Brian Wotring; Tuan Tran

2008-09-01

243

Effects of Diffusion Time on Short-Range Hyperpolarized 3He Diffusivity Measurements in Emphysema  

SciTech Connect

Purpose: To characterize the effect of diffusion time on short-range hyperpolarized 3He MR diffusion measurements across a wide range of emphysema severity. Materials and Methods: 3He diffusion MR imaging was performed on 19 lungs or lobes resected from 18 subjects with varying degrees of emphysema using 3 diffusion times (1.6 msec, 5 msec, and 10 msec) at constant b value. Emphysema severity was quantified as the mean apparent diffusion coefficient (ADC) and as the percentage of pixels with ADC higher than multiple thresholds from 0.30-0.55 cm2/sec (ADC index). Quantitative histology (mean linear intercept) was obtained in 10 of the lung specimens from 10 of the subjects. Results: The mean ADCs with diffusion times of 1.6, 5.0, and 10.0 msec were 0.46, 0.40, and 0.37 cm2/sec, respectively (P <0.0001, ANOVA). There was no relationship between the ADC magnitude and the effect of diffusion time on ADC values. Mean linear intercept correlated with ADC (r=0.91-0.94, P<0.001) and ADC index (r=0.78-0.92, P<0.01) at all diffusion times.

Gierada, David S.; Woods, Jason C.; Bierhals, Andrew J.; Bartel, Seth T.; Ritter, Jon H.; Choong, Cliff K.; Das, Nitin A.; Hong, Cheng; Pilgram, Thomas K.; Chang, Yulin V.; Jacob, Rick E.; Hogg, James C.; Battafarano, Richard J.; Cooper, Joel D.; Meyers, Bryan F.; Patterson, G Alexander; Yablonskiy, Dmitriy A.; Conradi, Mark S.

2009-09-28

244

An evaluation of the time-varying extended logistic, simple logistic, and Gompertz models for forecasting short product lifecycles  

Microsoft Academic Search

Many successful technology forecasting models have been developed but few researchers have explored a model that can best predict short product lifecycles. This research studies the forecast accuracy of long and short product lifecycle datasets using simple logistic, Gompertz, and the time-varying extended logistic models. The performance of the models was evaluated using the mean absolute deviation and the root

Charles V. Trappey; Hsin-ying Wu

2008-01-01

245

Inspiratory-phase short time scale synchrony in the brainstem slice is generated downstream of the pre-Bötzinger complex  

Microsoft Academic Search

Respiratory neurons are synchronized on a long time scale to generate inspiratory and expiratory-phase activities that are critical for respiration. Long time scale synchrony within the respiratory network occurs on a time scale of more than hundreds of milliseconds to seconds. During inspiration, neurons are synchronized on a short time scale to produce synchronous oscillations, which shape the pattern of

J. Y. Sebe; A. J. Berger

2008-01-01

246

Short-time behavior of the diffusion coefficient as a geometrical probe of porous media  

NASA Astrophysics Data System (ADS)

We investigate the time-dependent diffusion coefficient, D(t)=/(6t), of random walkers in porous media with piecewise-smooth pore-grain interfaces. D(t) is measured in pulsed-field-gradient spin-echo (PFGSE) experiments on fluid-saturated porous media. For reflecting boundary conditions at the interface we show that for short times D(t)/D0 =1-A0(D0t)1/2+B0D0t+O[(D0t)3/2], where A0=4S/(9 ?? VP) and B0=-HS/(12VP)-tsumi(Li/VP)f(?i). Here D0 is the diffusion constant of the bulk fluid, S/VP is the surface area to pore volume ratio, H is the mean curvature of the smooth portions of the surface, Li is the length of a wedge of angle ?i, and the function f(?) is defined below. More generally, we consider partially absorbing boundary conditions, where the absorption strength is controlled by a surface-relaxivity parameter ?. Here, the density of walkers (i.e., the net magnetization) decays as M(t)=1-?St/VP+..., and D(t) is defined as s/(6t), where s is the mean-square displacement of surviving walkers. When ??0 we find that the coefficient A0 of the ?D0t term in the above equation is unchanged, while the coefficient of the linear term changes to B0+?S/(6VP). Thus, data on D(t) and M(t) at short times may be used simultaneously to determine S/VP and ?. The limiting behavior of D(t) as ?-->? is also discussed.

Mitra, Partha P.; Sen, Pabitra N.; Schwartz, Lawrence M.

1993-04-01

247

Structure and short-time dynamics in concentrated suspensions of charged colloids.  

PubMed

We report a comprehensive joint experimental-theoretical study of the equilibrium pair-structure and short-time diffusion in aqueous suspensions of highly charged poly-acrylate (PA) spheres in the colloidal fluid phase. Low-polydispersity PA sphere systems with two different hard-core radii, R(0) = 542 and 1117 A?, are explored over a wide range of concentrations and salinities using static and dynamic light scattering (DLS), small angle x-ray scattering, and x-ray photon correlation spectroscopy (XPCS). The measured static and dynamic scattering functions are analyzed using state-of-the-art theoretical methods. For all samples, the measured static structure factor, S(Q), is in good agreement with results by an analytical integral equation method for particles interacting by a repulsive screened Coulomb plus hard-core pair potential. In our DLS and XPCS measurements, we have determined the short-time diffusion function D(Q) = D(0)?H(Q)?S(Q), comprising the free diffusion coefficient D(0) and the hydrodynamic function H(Q). The latter is calculated analytically using a self-part corrected version of the ??-scheme by Beenakker and Mazur which accounts approximately for many-body hydrodynamic interactions (HIs). Except for low-salinity systems at the highest investigated volume fraction ? ? 0.32, the theoretical predictions for H(Q) are in excellent agreement with the experimental data. In particular, the increase in the collective diffusion coefficient D(c) = D(Q ? 0), and the decrease of the self-diffusion coefficient, D(s) = D(Q ? ?), with increasing ? is well described. In accord with the theoretical prediction, the peak value, H(Q(m)), of H(Q) relates to the nearest neighbor cage size ?2??Q(m), for which concentration scaling relations are discussed. The peak values H(Q(m)) are globally bound from below by the corresponding neutral hard-spheres peak values, and from above by the limiting peak values for low-salinity charge-stabilized systems. HIs usually slow short-time diffusion on colloidal length scales, except for the cage diffusion coefficient, D(cge) = D(Q(m)), in dilute low-salinity systems where a speed up of the system dynamics and corresponding peak values of H(Q(m)) > 1 are observed experimentally and theoretically. PMID:22998268

Westermeier, Fabian; Fischer, Birgit; Roseker, Wojciech; Grübel, Gerhard; ägele, Gerhard; Heinen, Marco

2012-09-21

248

High nitrogen removal rate using ANAMMOX process at short hydraulic retention time.  

PubMed

The anaerobic ammonium oxidation (ANAMMOX) is a chemolithoautotrophic process, which converts NH(4)(+) to N(2) using nitrite (NO(2)(-)) as the electron acceptor. This process has very high nitrogen removal rates (NRRs) and is an alternative to classical nitrification/denitrification wastewater treatment. In the present work, a strategy for nitrogen removal using ANAMMOX process was tested evaluating their performance when submitted to high loading rates and very short hydraulic retention times (HRTs). An up-flow ANAMMOX column reactor was inoculated with 30% biomass (v v(-1)) fed from 100 to 200 mg L(-1) of total N (NO(2)(-)-N + NH(4)(+)-N) at 35 °C. After start-up and process stability the maximum NRR in the up-flow anaerobic sludge blanket (UASB) reactor was 18.3 g-N L(-1) d(-1) operated at 0.2 h of HRT. FISH (fluorescence in situ hybridization) analysis and process stoichiometry confirmed that ANAMMOX was the prevalent process for nitrogen removal during the experiments. The results point out that high NRRs can be obtained at very short HRTs using up-flow ANAMMOX column reactor configuration. PMID:23416586

Casagrande, C G; Kunz, A; De Prá, M C; Bressan, C R; Soares, H M

2013-01-01

249

Modeling of on-line catalyst addition effects in a short contact time reactor  

SciTech Connect

Recently developed short-contact-time reactors (SCTR), consisting of porous alumina monoliths coated with platinum, have been shown to produce ethylene from rich ethane/oxygen(hydrogen) mixtures with yields and selectivities comparable to conventional steam cracking, using a reactor of much smaller size. Although the overall mechanism is clearly autothermal and catalytic, the details, in particular the relative contributions of heterogeneous and homogeneous chemistry, are a matter of considerable debate. Recent experiments show that reactor performance can be further enhanced by dripping a dilute platinum solution onto the SCTR front face during reaction, resulting in catalyst deposition within only a short (several millimeter) zone of the reactor. The authors have undertaken a computational study of this system, using two-dimensional computational fluid dynamics simulations with full heat and mass transport and detailed heterogeneous and homogeneous kinetic mechanisms. The results indicate that front-face catalyst loading enhances reactor performance by limiting the opportunity for heterogeneous ethane reactions that produce methane. As a result, ethylene selectivity increases and CH{sub 4} selectivity decreases. The results strongly support a mechanism recently proposed by the authors, in which rapid, heterogeneous oxidation of adsorbed hydrogen consumes most of the oxygen. The resulting heat is then released to the gas phase, causing homogeneous pyrolysis of ethane to occur in an environment containing much less oxygen. This mechanism explains not only the effects of on-line catalyst addition, but also the increase in ethylene selectivity observed upon addition of hydrogen to the reactant mixture.

D. K. Zerkle; M. d. Allendorf; M. Wolf; O. Deutschmann

2000-07-30

250

42 CFR 488.30 - Revisit user fee for revisit surveys.  

Code of Federal Regulations, 2010 CFR

... false Revisit user fee for revisit surveys. 488.30 Section 488.30 Public...CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES...488.30 Revisit user fee for revisit surveys. (a) Definitions. As used...

2010-10-01

251

Qualitative Features Extraction from Sensor Data using Short-time Fourier Transform  

NASA Technical Reports Server (NTRS)

The information gathered from sensors is used to determine the health of a sensor. Once a normal mode of operation is established any deviation from the normal behavior indicates a change. This change may be due to a malfunction of the sensor(s) or the system (or process). The step-up and step-down features, as well as sensor disturbances are assumed to be exponential. An RC network is used to model the main process, which is defined by a step-up (charging), drift, and step-down (discharging). The sensor disturbances and spike are added while the system is in drift. The system runs for a period of at least three time-constants of the main process every time a process feature occurs (e.g. step change). The Short-Time Fourier Transform of the Signal is taken using the Hamming window. Three window widths are used. The DC value is removed from the windowed data prior to taking the FFT. The resulting three dimensional spectral plots provide good time frequency resolution. The results indicate distinct shapes corresponding to each process.

Amini, Abolfazl M.; Figueroa, Fernando

2004-01-01

252

Stationarity coefficients and short-time deviations from exponential decay in atomic resonance states  

NASA Astrophysics Data System (ADS)

By solving rigorously and accurately the time-dependent Schrödinger equation, we have obtained numerical results for the decay probability, P(t), of real, multiparticle systems, in the time domain of t~0. Three different types of atomic nonstationary states were examined, the He- 1s2p2 4P, the Ca KLM 3d5p 3Fo, and the He- 1s2s2p 4P5/2, the last one being metastable and decaying via spin-spin interactions. The main results are that there is a t2 dependence of P(t~0) and that a time-dependent short-time decay rate can be calculated. The computed coefficients of the t2 term reflect the degree of stability of the state, (i.e., the degree of proximity to the notion of the standard stationary state of quantum mechanics), and are named the stationarity coefficients. These, together with the conventional quantity of the lifetime, corresponding to the exponential decay regime, constitute intrinsic properties of each real unstable state. For the herein studied metastable state the onset of exponential decay occurs after about 5×10-14 s, i.e., after a duration which is achievable experimentally with laser pulses.

Mercouris, Theodoros; Nicolaides, Cleanthes A.

2002-01-01

253

Fluctuation of similarity to detect transitions between distinct dynamical regimes in short time series  

NASA Astrophysics Data System (ADS)

A method to identify distinct dynamical regimes and transitions between those regimes in a short univariate time series was recently introduced [N. Malik et al., Europhys. Lett. 97, 40009 (2012), 10.1209/0295-5075/97/40009], employing the computation of fluctuations in a measure of nonlinear similarity based on local recurrence properties. In this work, we describe the details of the analytical relationships between this newly introduced measure and the well-known concepts of attractor dimensions and Lyapunov exponents. We show that the new measure has linear dependence on the effective dimension of the attractor and it measures the variations in the sum of the Lyapunov spectrum. To illustrate the practical usefulness of the method, we identify various types of dynamical transitions in different nonlinear models. We present testbed examples for the new method's robustness against noise and missing values in the time series. We also use this method to analyze time series of social dynamics, specifically an analysis of the US crime record time series from 1975 to 1993. Using this method, we find that dynamical complexity in robberies was influenced by the unemployment rate until the late 1980s. We have also observed a dynamical transition in homicide and robbery rates in the late 1980s and early 1990s, leading to increase in the dynamical complexity of these rates.

Malik, Nishant; Marwan, Norbert; Zou, Yong; Mucha, Peter J.; Kurths, Jürgen

2014-06-01

254

Time- and space-resolved microscopy of induced ablation with ultra-short laser pulses  

NASA Astrophysics Data System (ADS)

Laser lift-off processes have been observed during structuring CIS thin film solar cells with ultra-short laser pulses, if a Mo film on glass is irradiated from the glass substrate side. To investigate the underlying physical effects, ultrafast pump-probe microscopy is used for time- and space resolved investigations. The setup utilizes a 660 fs-laser pulse at a wavelength of 1053 nm that is split up into a pump and a probe pulse. The pump pulse ablates the thin film, while the frequency doubled probe pulse illuminates the ablation area after an optically defined delay time of up to 4 ns. For longer delay times, a second electronically triggered 600 ps-laser is used for probing. Thus, the complete ultra fast pulse initiated ablation process can be observed in a delay time range from femtoseconds to microseconds. First experiments on the directly induced ablation of molybdenum films from the glass substrate side show that mechanical deformation is initiated at about 400 ps after the impact of the pump laser pulse. The deformation continues until approximately 15 ns, then a Mo disk shears and lifts-off with a velocity of above 70 m/s free from thermal effects.

Domke, Matthias; Rapp, Stephan; Heise, Gerhard; Huber, Heinz P.

2012-02-01

255

Short-time scale correlation between slow slip and tremor in Cascadia  

NASA Astrophysics Data System (ADS)

We use borehole strain and seismic data to show that slow slip and tremor in central Cascadia are correlated on a range of time scales shorter than 1 day. The recorded strain rate is our proxy for the slow slip moment rate, and the seismic amplitude is our proxy for the tremor amplitude. We find that, on average, the strain rate is higher when the seismic amplitude is larger. This correlation persists on time scales between 15 min and 16 h, and it can be seen in each of the five slow slip events between 2007 and 2011. Our results imply that the slow slip moment rate varies by a large amount even at these short time scales. For instance, we observe a factor of 2 variation on time scales shorter than 4 h. This apparently aperiodic variation is larger than the previously observed variation in moment rate resulting from tidal forcing. It is a lower bound on the actual moment rate variation, as we detect only changes in slow slip that are correlated with tremor amplitude.

Hawthorne, J. C.; Rubin, A. M.

2013-03-01

256

Gene expression profiling of canine osteosarcoma reveals genes associated with short and long survival times  

PubMed Central

Background Gene expression profiling of spontaneous tumors in the dog offers a unique translational opportunity to identify prognostic biomarkers and signaling pathways that are common to both canine and human. Osteosarcoma (OS) accounts for approximately 80% of all malignant bone tumors in the dog. Canine OS are highly comparable with their human counterpart with respect to histology, high metastatic rate and poor long-term survival. This study investigates the prognostic gene profile among thirty-two primary canine OS using canine specific cDNA microarrays representing 20,313 genes to identify genes and cellular signaling pathways associated with survival. This, the first report of its kind in dogs with OS, also demonstrates the advantages of cross-species comparison with human OS. Results The 32 tumors were classified into two prognostic groups based on survival time (ST). They were defined as short survivors (dogs with poor prognosis: surviving fewer than 6 months) and long survivors (dogs with better prognosis: surviving 6 months or longer). Fifty-one transcripts were found to be differentially expressed, with common upregulation of these genes in the short survivors. The overexpressed genes in short survivors are associated with possible roles in proliferation, drug resistance or metastasis. Several deregulated pathways identified in the present study, including Wnt signaling, Integrin signaling and Chemokine/cytokine signaling are comparable to the pathway analysis conducted on human OS gene profiles, emphasizing the value of the dog as an excellent model for humans. Conclusion A molecular-based method for discrimination of outcome for short and long survivors is useful for future prognostic stratification at initial diagnosis, where genes and pathways associated with cell cycle/proliferation, drug resistance and metastasis could be potential targets for diagnosis and therapy. The similarities between human and canine OS makes the dog a suitable pre-clinical model for future 'novel' therapeutic approaches where the current research has provided new insights on prognostic genes, molecular pathways and mechanisms involved in OS pathogenesis and disease progression.

Selvarajah, Gayathri T; Kirpensteijn, Jolle; van Wolferen, Monique E; Rao, Nagesha AS; Fieten, Hille; Mol, Jan A

2009-01-01

257

Short-time dynamics of a packing of polyhedral grains under horizontal vibrations  

NASA Astrophysics Data System (ADS)

We analyze the dynamics of a 3D granular packing composed of particles of irregular polyhedral shape confined inside a rectangular box with a retaining wall subjected to horizontal harmonic forcing. The simulations are performed by means of the contact dynamics method for a broad set of loading parameters. We explore the vibrational dynamics of the packing, the evolution of solid fraction and the scaling of dynamics with the loading parameters. We show that the motion of the retaining wall is strongly anharmonic as a result of jamming and grain rearrangements. It is found that the mean particle displacement scales with inverse square of frequency, the inverse of the force amplitude and the square of gravity. The short-time compaction rate grows in proportion to frequency up to a characteristic frequency, corresponding to collective particle rearrangements between equilibrium states, and then it declines in inverse proportion to frequency.

Azéma, E.; Radjaï, F.; Peyroux, R.; Richefeu, V.; Saussine, G.

2008-07-01

258

Transient polar motions and the nature of the asthenosphere for short time scales  

NASA Technical Reports Server (NTRS)

A uniformly valid mathematical formalism is developed to study the secular motions of the rotational axis of a layered viscoelastic earth due to seismic excitation. The changes required for implementing the formulation within the framework of the faulting problem. The rationale of adopting the chosen nrheological model, which contains a low-viscosity zone beneath the lithosphere and is based on linear Maxell constitutive relationship, is discussed. The impact of this low-viscosity channel on thhe two families of relaxation time, governing both isostatic readjustment and rotational processes, is considered. It is found that the polar motions depend sensitively on the viscosity structure of the asthenosphere and not at all on the underlying mantle. A gloal low-velocity zone with short-term asthenospheric viscosities less than about 5 x 10 to the 18th Pa-s and widths greater than 50 km is ruled out.

Boschi, E.; Sabadini, R.; Yuen, D. A.

1985-01-01

259

Instantaneous Heart Rate detection using short-time autocorrelation for wearable healthcare systems.  

PubMed

This report describes a robust method of Instantaneous Heart Rate (IHR) detection from noisy electrocardiogram (ECG) signals. Generally, the IHR is calculated from the interval of R-waves. Then, the R-waves are extracted from the ECG using a threshold. However, in wearable biosignal monitoring systems, various noises (e.g. muscle artifacts from myoelectric signals, electrode motion artifacts) increase incidences of misdetection and false detection because the power consumption and electrode distance of the wearable sensor are limited to reduce its size and weight. To prevent incorrect detection, we use a short-time autocorrelation technique. The proposed method uses similarity of the waveform of the QRS complex. Therefore, it has no threshold calculation Process and it is robust for noisy environment. Simulation results show that the proposed method improves the success rate of IHR detection by up to 37%. PMID:23367467

Nakano, Masanao; Konishi, Toshihiro; Izumi, Shintaro; Kawaguchi, Hiroshi; Yoshimoto, Masahiko

2012-01-01

260

A direct approach to control short term population dynamics in time series studies  

PubMed Central

Background: Short term population dynamics is an important issue in several epidemiological studies. Usually, calendar time or dummy variables are used to control indirectly for this confounding. This study tested a direct method. Methods: The study compared as proxy variables of population dynamics the summer 2003 data of cooking gas consumptions, solid urban waste production, and television access for the municipality of Bologna (Italy). Results: Solid urban waste production and television access data showed similar trends. Considerably different were the >65 year olds estimates with respect to total population based on television access. Conclusions: Television access data are probably the best indicator in the estimates of population dynamics in large or densely populated areas, especially because of the possibility of stratifications with respect to age.

Zauli, S; Scotto, F.; Lauriola, P.

2005-01-01

261

Short and long-time solutions for material balance equation in lithium-ion batteries by Laplace transform  

Microsoft Academic Search

Short- and long-time solutions for material balance equations for porous electrodes in both the solid and the solution phase is presented. These solutions represent the concentration profile of lithium-ions in the solid and solution phases of the positive electrode of a lithium-ion cell, and are obtained using the method of Laplace transform for short- and long-time intervals.

S. A. Hashim Ali; A. Hussin; A. K. Arof

2002-01-01

262

Short-time scaling via Monte Carlo single spin-flip algorithms for the Baxter–Wu model  

Microsoft Academic Search

The short-time critical dynamics of the Baxter–Wu model is investigated via Monte Carlo simulations using single spin-flip algorithms. The critical dynamic exponents z and ? are estimated and it is shown that the N-fold way provides a reliable estimate for the ratio of the static exponents (2?\\/?) and a good confirmation of the short-time scheme. However, we find that the

I. A. Hadjiagapiou; A. Malakis; S. S. Martinos

2005-01-01

263

Short-time dynamics of colloidal particles confined between two walls  

NASA Astrophysics Data System (ADS)

The short-time dynamics of colloidal particles in a quasi-two-dimensional geometry is studied by digital video microscopy. The particles (polystyrene spheres) are suspended in water and confined between two parallel glass plates, forming an effective two-dimensional system. The (effective) two-dimensional van Hove function G(r,t) and its self and distinct part are measured with a time resolution of 1/30 s. We found that the general behavior of these time-correlation functions (and their Fourier transforms) is quite similar to that of their three-dimensional counterparts. The effects of the strong hydrodynamic coupling of the particles motion to the walls and that due to the hydrodynamic interactions between particles are contained in the (effective) hydrodynamic function H(k) obtained from the initial slope of F(k,t) [the Fourier transform of G(r,t)]. We found that H(k), as a function of the wave vector k and particle concentration, exhibits a similar qualitative behavior to the hydrodynamic function in homogeneous three-dimensional suspensions of hard spheres. We also found in our systems that the particle fluctuations relax only by self-diffusion for wave vectors where the static structure factor S(k)=1. This result is important for measurements of self-diffusion dynamics in three-dimensional systems by light scattering techniques.

Santana-Solano, Jesús; Arauz-Lara, José Luis

2002-02-01

264

Laser-induced short time scale thermal chemistry of perfluoropolyether lubricant films  

SciTech Connect

The authors investigate the effect of heating a perfluoropolyether lubricant film in a localized area for relatively short time periods using laser irradiation versus conventional oven heating. These experiments help provide understanding on how flash temperatures generated at frictional contacts affect the thermal chemistry of lubricant films. In these experiments, a CO{sub 2} laser heats a 50 {micro}m wide area of a silicon wafer for time periods ranging from 0.1 to 60 s. The surface temperature within the heated area (up to 280 C in these experiments) is monitored with a second laser by measuring the change in reflectivity near the center of the heated area. A major difference observed for laser heating compared to oven heating is that the effective evaporation rate is orders of magnitude higher for laser heating. If the lubricant film is heated for sufficiently long enough time at high temperatures, the authors are able to observe thermal bonding of the lubricant via its alcohol end groups to the silicon oxide surface, followed by thermal decomposition of the lubricant molecules. After laser heating, the authors are able to observe the diffusion of lubricant back into the localized heated area using a combination of optical microscopy and imaging ellipsometry.

Heller, J.; Mate, C.J.; Poon, C.C.; Tam, A.C.

1999-11-09

265

Complexity signatures for short time scales in the atmosphere above Adventdalen, Svalbard  

NASA Astrophysics Data System (ADS)

parameters from the troposphere above Adventdalen, Svalbard, 78°N, 16°E, are examined for signatures of complexity in their respective stochastic components over time scales from ~1 h to 1 year. Several approaches are used, all of which can estimate values of the generalized Hurst exponent, ?, which can in turn be compared with each other and with similar independent characterizations, usually via the classic Hurst exponent, H, obtained from location-specific and globally averaged time series. For tropopause altitude, the stochastic component exhibits the signature of a persistent fractional Gaussian noise (fGn) with ? ? 0.75. For surface air temperature, the indications are for fractional Brownian motion (fBm) with ? ? 1.4. Using recent high time-resolution data from a single high-latitude location, this identification of fBm is relevant for short-term memory as opposed to findings from many other studies addressing possible long-term memory, which demonstrate fGn with ? = H ? 0.7. Furthermore, the lack of similarity between the results for surface air temperature and tropopause altitude suggests that different underlying processes are responsible for stochastic variability.

Hall, C. M.

2014-01-01

266

Optimization of Inversion Time for Postmortem Short-tau Inversion Recovery (STIR) MR Imaging.  

PubMed

Purpose: Signal intensity and image contrast differ between postmortem magnetic resonance (PMMR) images and images acquired from the living body. We sought to achieve sufficient fat suppression with short-tau inversion recovery (STIR) PMMR imaging by optimizing inversion time (TI).Material and Methods: We subjected 37 deceased adult patients to PMMR imaging at 1.5 tesla 8 to 60 hours after confirmation of death and measured T1 values of areas of subcutaneous fat with relaxation time maps. Rectal temperature (RT) measured immediately after PMMR ranged from 6 to 31°C. We used Pearson's correlation coefficient to analyze the relationship between T1 and relaxation time (RT). We compared STIR images from 4 cadavers acquired with a TI commonly used in the living body and another TI calculated from the linear regression of T1 and RT.Results: T1 values of subcutaneous fat ranged from 89.4 to 182.2 ms. There was a strong, positive, and significant correlation between T1 and RT (r = 0.91, P < 0.0001). The regression expression for the relationship was T1 = 2.6*RT + 90 at a field strength of 1.5T. The subcutaneous fat signal was suppressed more effectively with the optimized TI.Conclusion: The T1 value of subcutaneous fat in PMMR correlates linearly with body temperature. Using this correlation to determine TI, fat suppression with PMMR STIR imaging can be easily improved. PMID:24769635

Kobayashi, Tomoya; Monma, Masahiko; Baba, Takeshi; Ishimori, Yoshiyuki; Shiotani, Seiji; Saitou, Hajime; Kaga, Kazunori; Miyamoto, Katsumi; Hayakawa, Hideyuki; Homma, Kazuhiro

2014-06-23

267

Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations.  

PubMed

A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent. PMID:17335934

Kim, Kyunghan; Guo, Zhixiong

2007-05-01

268

Temporal Moments revisited: Why there is there no better way for physically-based model reduction in time  

NASA Astrophysics Data System (ADS)

Many hydrogeological problems are highly complex in space and time, coupled with scale issues, variability and uncertainty. Especially time-dependent models often consume enormous computational resources. Model reduction techniques make stochastic modeling, probabilistic risk assessment and inverse problems more accessible to large-scale realistic applications. Temporal Moments (TM) are a promising approach to reduce the time demands and complexity of transient hydrogeological simulations. They reduce transient governing equations to steady-state and directly simulate the temporal characteristics of the system, if the equations are linear and coefficients are time-independent. This is achieved by an integral transform, projecting the dynamic system response onto monomials in time. In comparison to classical approaches of model reduction that involve orthogonal base functions, however, the monomials used for TM are non-orthogonal base functions, and this might impair the quality and efficiency of model reduction. Thus, we raise the question if there are more suitable temporal base-functions than the monomials that lead to TM. In this work, we will derive theoretically that there is only a limited class of temporal base functions that can reduce hydrogeological models. By comparing those to TM we conclude that, in terms of gained efficiency versus maintained accuracy, TM are the best possible choice. While our theoretical results hold for all systems of linear PDEs with any order of time derivations, we illustrate our study with an example on pumping tests in a confined aquifer. For that, we demonstrate that using two or three TM is sufficient to represent more than 90 % of the dynamic behavior.

Leube, P.; Nowak, W.; Schneider, G.

2011-12-01

269

Revisiting the Regenerative Possibilities of Ortiz  

ERIC Educational Resources Information Center

The author of this article revisits Simon Ortiz's poem, "From Sand Creek," in which the latter can in so few words convey both the horrific tragedy of conquest and colonization, while at the same time find a space for possibility, a means for recovery that is never about forgetting but always occurs as a kind of recuperative remembering. Ortiz…

Duques, Matthew

2004-01-01

270

Real-time monitoring and short-term forecasting of drought in Norway  

NASA Astrophysics Data System (ADS)

Drought is considered to be one of the most costly natural disasters. Drought monitoring and forecasting are thus important for sound water management. In this study hydrological drought characteristics applicable for real-time monitoring and short-term forecasting of drought in Norway were developed. A spatially distributed hydrological model (HBV) implemented in a Web-based GIS framework provides a platform for drought analyses and visualizations. A number of national drought maps can be produced, which is a simple and effective way to communicate drought conditions to decision makers and the public. The HBV model is driven by precipitation and air temperature data. On a daily time step it calculates the water balance for 1 x 1 km2 grid cells characterized by their elevation and land use. Drought duration and areal drought coverage for runoff and subsurface storage (sum of soil moisture and groundwater) were derived. The threshold level method was used to specify drought conditions on a grid cell basis. The daily 10th percentile thresholds were derived from seven-day windows centered on that calendar day from the reference period 1981-2010 (threshold not exceeded 10% of the time). Each individual grid cell was examined to determine if it was below its respective threshold level. Daily drought-stricken areas can then be easily identified when visualized on a map. The drought duration can also be tracked and calculated by a retrospective analysis. Real-time observations from synoptic stations interpolated to a regular grid of 1 km resolution constituted the forcing data for the current situation. 9-day meteorological forecasts were used as input to the HBV model to obtain short-term hydrological drought forecasts. Downscaled precipitation and temperature fields from two different atmospheric models were applied. The first two days of the forecast period adopted the forecasts from Unified Model (UM4) while the following seven days were based on the 9-day forecasts from ECMWF. The approach has been tested and is now available on the Web for operational water management.

Kwok Wong, Wai; Hisdal, Hege

2013-04-01

271

Network Nation Revisited  

NSDL National Science Digital Library

The Network Nation Revisited" is an analysis of the predictions made by Hiltz and Turoff in _The Network Nation_, one of the seminal texts (published in 1978) in the field of Computer Mediated Communications.

272

Revisiting the Question: Does High-latitude Solar Activity Lead Low-latitude Solar Activity in Time Phase?  

NASA Astrophysics Data System (ADS)

Cross-correlation analysis and wavelet transform methods are used to investigate whether high-latitude solar activity leads low-latitude solar activity in time phase or not, using the data of the Carte Synoptique solar filaments archive from 1919 March to 1989 December. From the cross-correlation analysis, high-latitude solar filaments have a time lead of 12 Carrington solar rotations with respect to low-latitude ones. Both the cross-wavelet transform and wavelet coherence indicate that high-latitude solar filaments lead low-latitude ones in time phase. Furthermore, low-latitude solar activity is better correlated with high-latitude solar activity of the previous cycle than with that of the following cycle, which is statistically significant. Thus, the present study confirms that high-latitude solar activity in the polar regions is indeed better correlated with the low-latitude solar activity of the following cycle than with that of the previous cycle, namely, leading in time phase.

Kong, D. F.; Qu, Z. N.; Guo, Q. L.

2014-05-01

273

The Evil Empire Revisited: New York Times Coverage of the Soviet Intervention in and Withdrawal from Afghanistan  

Microsoft Academic Search

This study examines the New York Times coverage of the Soviet intervention and withdrawal from Afghanistan from 1979 to 1989. Changes in coverage are examined in the context of easing tensions between the U.S. and the former Soviet Union. Findings indicate that the treatment of major story elements was consistent with Herman and Chomsky's propaganda framework. However, changes in the

Jothik Krishnaiah; Nancy Signorielli; Douglas M. McLeod

1993-01-01

274

Revisiting the Impact of Part-Time Work on Adolescent Adjustment: Distinguishing between Selection and Socialization Using Propensity Score Matching  

ERIC Educational Resources Information Center

The impact of part-time employment on adolescent functioning remains unclear because most studies fail to adequately control for differential selection into the workplace. The present study reanalyzes data from L. Steinberg, S. Fegley, and S. M. Dornbusch (1993) using multiple imputation, which minimizes bias in effect size estimation, and 2 types…

Monahan, Kathryn C.; Lee, Joanna M.; Steinberg, Laurence

2011-01-01

275

Evidence for two distinct morphological classes of gamma-ray bursts from their short time scale variability  

NASA Technical Reports Server (NTRS)

We have analyzed the 241 bursts for which peak counts (C)max exist in the publicly available Burst and Transient Source Experiment (BATSE) catalog. Introducing peak counts in 1024 ms as a measure of burst brightness B and the ratio of peak counts in 64 and 1024 ms as a measure of short timescale variability V, we find a statistically significant correlation between the brightness and the short time scale variability of gamma-ray bursts. The bursts which are smoother on short time scales are both faint and bright, while the bursts which are variable on short time scales are faint only, suggesting the existence of two distinct morphological classes of bursts.

Lamb, D. Q.; Graziani, C.; Smith, I. A.

1993-01-01

276

Assessing stomatal conductance changes on short and long time scales and its possible impact on climate  

NASA Astrophysics Data System (ADS)

Two fundamental responses of vegetation to increasing atmospheric CO2 concentrations ([CO2]) are increased photosynthesis and decreased stomatal conductance. The latter is determined by both stomatal aperture adjustment on the short term, and by stomatal frequency and size adjustment on the long term. The resulting increased WUE of vegetation leads to changes in the hydrological cycle. Integrating this physiological forcing in Global Circulation Models (GCMs) results in increased surface warming and is thought to enhance terrestrial runoff significantly. Stomatal conductance is therefore considered a critical parameter in modelling past and future climate and environmental changes. However, quantification of the rate of change under [CO2] variability has proven to be not so straightforward. Values obtained from growth experiments under elevated [CO2] generally reflect the short term adaptation only, and seem to have too short a runtime for structural adaptation of the vegetation. Here we present the stomatal conductance changes deduced from Florida subfossil leaves over a 100ppmv [CO2] increment since the industrial revolution. Temporally high-resolution measurements of stomatal frequency and size on the epidermis for 8 common Florida tree species (Taxodium distichum, Pinus elliottii, P. taeda, Quercus nigra, Q. laurifolia, Acer rubrum, Myrica cerifera and Ilex cassine) are used to calculate the maximal stomatal conductance to water vapour Gwmax. Resulting conductance decreases over a 100ppmv [CO2] interval range between -19% to -59% for the different species, with an average of -40%. The current warm-temperate to subtropical Florida climate and vegetation composition serve as a modern analogue for Late Tertiary Europe, when [CO2] is thought to be comparable to today's levels. If it is assumed that past vegetation has responded similarly to [CO2] fluctuations, the stomatal conductance change reconstructed for Florida and related WUE changes can be used to better understand hydrological and climatological changes further back in the geological history. As a corollary we present for the first time stomatal conductance Gwmax from Miocene and Pliocene oak leaves. Mainly the stomatal density changes on these leaves result in significant fluctuations in Gwmax, as a consequence of variation in palaeoatmospheric CO2.

Lammertsma, Emmy; Wagner-Cremer, Friederike; Kuerschner, Wolfram M.

2010-05-01

277

Time-evolution scenarios for short-range depletion gels subjected to the gravitational stress.  

PubMed

By exploiting photon correlation imaging and ghost particle velocimetry, two novel optical correlation techniques particularly suited to the investigation of the microscopic dynamics of spatially heterogeneous samples, we investigate the settling and restructuring dynamics of colloidal gels generated by short-ranged depletion interactions. Three distinct regions can be clearly set apart within the liquid-liquid coexistence region of the phase diagram where gel formation is observed. When depletion forces are barely sufficient to drive the system within the metastable region, an initial disordered gel hosts the rapid nucleation of crystallites, which stress the gel structure until it fully collapses, leading to the formation of a macroscopic colloidal crystal. For stronger attractive forces, two distinct scenarios are observed, depending on the particle volume fraction ?0 of the original suspension. At low ?0, the gel breaks after a short delay time into separate clusters, which rapidly settle until they compact in a denser disordered phase. The latter eventually undergoes a slow compression, which is accounted for by a poroelastic model where the microscopic gel dynamics is fully ruled by its macroscopic deformation. Yet, it is the intermediate stage between cluster settling and final compaction which displays very peculiar features, evidenced by anomalous settling profiles which are not shared, to our knowledge, by any other sedimentation processes investigated so far. For larger values of ?0, gel breaking is conversely suppressed, the structure undergoes a continuous compression that cannot be explained by a poroelastic model, and the microscopic dynamics is characterized by logarithmic correlation functions resembling those found for attractive glasses. PMID:24913393

Secchi, Eleonora; Buzzaccaro, Stefano; Piazza, Roberto

2014-08-01

278

Long and short time variations of the Na/K ratio in the exosphere of Mercury.  

NASA Astrophysics Data System (ADS)

Here we present the results of our model for the short-time and yearly variations of the Sodium and Potassium exosphere of Mercury. Such surface-bounded exosphere is produced by release processes occurring at the planetary surface, such as ion sputtering, thermal- or photon-stimulated desorption. The amount of surface Sodium or Potassium that is available for release, however, is limited. Those release processes deplete the surface in Na and K, which is continuously refilled by diffusion from the interior of regolith grains or by chemical sputtering. Ejected particles may either escape the gravity field, assisted by the radiation pressure acceleration, or be photoionized, or fall back onto the surface. Falling particles will stick to the surface. A Montecarlo model, simulating all these processes, is used to obtain the exosphere densities and the Na/K ratio, taking into account the planet's orbit and rotation speed. The influence of variations of the solar wind precipitation (i.e., CMEs) is also included. We compare this model with either ground- and space-based observations of the exosphere and tail to evaluate the effectiveness of each source process. We find that including a source process which effectiveness is proportional to the precipitation of solar wind protons, is necessary to explain most of the available observations in both qualitative and quantitative way. We find that, to reproduce dawn-dusk asymmetries, we need to include the rotation of Mercury's surface in the model. After finding the correct model parameter by calibrating the model with observation, we simulate the short-term and yearly variations of Na/K.

Mura, Alessandro; Lammer, Helmut; Wurz, Peter; Orsini, Stefano; Milillo, Anna; Mangano, Valeria; Lichtenegger, Herbert; Scherf, Manuel; Khodachenko, Maxim; Pfleger, Martin

2014-05-01

279

Progenitor delay-time distribution of short gamma-ray bursts: Constraints from observations  

NASA Astrophysics Data System (ADS)

Context. The progenitors of short gamma-ray bursts (SGRBs) have not yet been well identified. The most popular model is the merger of compact object binaries (NS-NS/NS-BH). However, other progenitor models cannot be ruled out. The delay-time distribution of SGRB progenitors, which is an important property to constrain progenitor models, is still poorly understood. Aims: We aim to better constrain the luminosity function of SGRBs and the delay-time distribution of their progenitors with newly discovered SGRBs. Methods: We present a low-contamination sample of 16 Swift SGRBs that is better defined by a duration shorter than 0.8 s. By using this robust sample and by combining a self-consistent star formation model with various models for the distribution of time delays, the redshift distribution of SGRBs is calculated and then compared to the observational data. Results: We find that the power-law delay distribution model is disfavored and that only the lognormal delay distribution model with the typical delay ? ? 3 Gyr is consistent with the data. Comparing Swift SGRBs with T90 > 0.8 s to our robust sample (T90 < 0.8 s), we find a significant difference in the time delays between these two samples. Conclusions: Our results show that the progenitors of SGRBs are dominated by relatively long-lived systems (? ? 3 Gyr), which contrasts the results found for Type Ia supernovae. We therefore conclude that primordial NS-NS systems are not favored as the dominant SGRB progenitors. Alternatively, dynamically formed NS-NS/BH and primordial NS-BH systems with average delays longer than 5 Gyr may contribute a significant fraction to the overall SGRB progenitors.

Hao, Jing-Meng; Yuan, Ye-Fei

2013-10-01

280

Short time series analysis of Didymosphenia geminata blooming in the Oreti River, New Zealand  

NASA Astrophysics Data System (ADS)

The mat-forming diatom Didymosphenia geminata was introduced to New Zealand in 2004, and subsequently spread to many rivers on the south island. D geminata mats are exceptionally dense and thick. Extensive blooms of this introduced organism have substantially modified the benthic environment in many New Zealand rivers, but the factors that contribute to D. geminata blooming are not well understood. We synthesized a sequence of observations of D. geminata areal coverage and thickness to examine physical and chemical controls on the growth and persistence of D germinata. We analyzed the best available time series on the distribution of this organism in New Zealand, observations in the Oreti River every 15 days spanning April 2006 to May 2007. During this period, mean D. geminata coverage of the river bed was ~52% and the mean mat thickness was ~6 mm. Relationships between time-series observations of D. geminata and 13 different physical and chemical variables were analyzed using linear and nonlinear methods. Areal cover and thickness of D geminata mats were found to be influenced by both slow and fast dynamic processes. The spread of the organism, in terms of % cover, was highly correlated with conductivity, ammonium, nitrate, dissolved oxygen, and total nitrogen with short time lags (fast dynamics). Moreover, water clarity, cloud cover, and flow were highly correlated with % cover with long time lags, indicating that these conditions exert long-term control on D. geminata growth. Areal coverage and thickness were found to be highly correlated, but the variables associated with slow and fast dynamics of these two measures were not identical. The variables found to be highly correlated with D. germinata thickness and represented fast dynamics were temperature, dissolved oxygen, conductivity, nitrate, and total nitrogen. Additionally, the variables influencing the slow dynamics of D. germinata thickness were flow, water clarity, turbidity and total phosphorous.

Garcia, T.; Kilroy, C.; Larned, S.; Packman, A. I.; Kumar, P.

2010-12-01

281

Rapid growth, early maturation and short generation time in African annual fishes  

PubMed Central

Background Extreme environmental conditions can give rise to extreme adaptations. We document growth, sexual maturation and fecundity in two species of African annual fish inhabiting temporary savanna pools. Results Nothobranchius kadleci started to reproduce at the age of 17 days and size of 31 mm and Nothobranchius furzeri at 18 days and 32 mm. All four study populations demonstrated rapid growth rates of up to 2.72 mm/day (23.4% of their total length). Both species may produce diapausing embryos or embryos that are able to hatch in as few as 15 days, resulting in a minimum generation time as short as only one month. Incubation on the surface of damp peat moss results in high embryo survival (73%) and a high proportion of rapidly developing embryos (58%) that skip diapauses and hatch in less than 30 days. We further demonstrated that rapid growth and maturation do not compromise subsequent fecundity. Conclusions Our data suggest that both species have the most rapid sexual maturation and minimum generation time of any vertebrate species, and that rapid maturity does not involve paedogenesis.

2013-01-01

282

Timing of introduction of complementary food: short- and long-term health consequences.  

PubMed

Complementary food is needed when breast milk (or infant formula) alone is no longer sufficient for both nutritional and developmental reasons. The timing of its introduction, therefore, is an individual decision, although 6 months of exclusive breastfeeding can be recommended for most healthy term infants. The new foods are intended to 'complement' ongoing breastfeeding with those dietary items whose intake has become marginal or insufficient. Both breastfeeding and complementary feeding can have direct or later consequences on health. The evaluation of consequences of both early and late introduction of complementary food can neither disregard the effect of breastfeeding compared to formula feeding nor the composition or quality of the complementary food. Possible short-term health effects concern growth velocity and infections, and possible long-term effects may relate to atopic diseases, type 1 and 2 diabetes, obesity and neuromuscular development. On the basis of the currently available evidence, it is impossible to exactly determine the age when risks related to the start of complementary feeding are lowest or highest for most of these effects, with the possible exception of infections and early growth velocity. The present knowledge on undesirable health effects, however, is mainly based on observational studies, and although some mechanisms have been proposed, further prospective studies have to clarify these unsolved issues. Even less evidence on the consequences of the timing of complementary food introduction is available for formula-fed infants. PMID:22555185

Przyrembel, Hildegard

2012-01-01

283

Properties of Visna Virus Particles Harvested at Short Time Intervals: RNA Content, Infectivity, and Ultrastructure  

PubMed Central

The major RNA component of Visna virus harvested at short intervals of time (5 min) is not the 60 to 70S RNA but a molecule of higher electrophoretic mobility. This RNA has been isolated and characterized. Its sedimentation coefficient is identical to that of 30 to 40S RNA subunits obtained by heat denaturation of the 60 to 70S RNA. In 1.8% acrylamide gels without agarose the electrophoretic mobility of 30 to 40S RNA subunits present in rapidly harvested virus is slightly lower than that of the subunits obtained by denaturation of the 60 to 70S RNA; after heat denaturation the mobilities are identical. These free RNA subunits present in early virus particles assemble into a 60 to 70S RNA complex as shown by following the RNA content of early virus incubated at 37 C for various lengths of time. The rate of this maturation process is slow. There is no difference between the infectivity of immature and mature virus particles. Both particles have a dense core when examined in sections of virus pellets. Images

Brahic, M.; Vigne, R.

1975-01-01

284

Short time exposure to hydrogen peroxide induces sustained glutathione export from cultured neurons.  

PubMed

Hydrogen peroxide is a normal by-product of cellular metabolism that in higher concentrations can cause oxidative stress. Cultured cerebellar granule neurons efficiently disposed of micromolar concentrations of hydrogen peroxide with half-times in the minute range in a process that predominately involved catalase. Application of up to 100µM hydrogen peroxide did not affect the cell viability for up to 4h, but caused a time- and concentration-dependent increase in the extracellular glutathione (GSH) content that was accompanied by a matching decrease in the cellular GSH content. Hydrogen peroxide at 100µM stimulated maximally the GSH export from viable neurons, but did not affect GSH export from cultured astrocytes. The peroxide-induced extracellular GSH accumulation from neurons was lowered by 70% in the presence of MK571, an inhibitor of multidrug resistance protein (Mrp) 1. The extracellular GSH content determined after 4h of incubation was already significantly increased after a 5-min exposure of neurons to hydrogen peroxide and became maximal after 15min of peroxide application. These data demonstrate that just a short exposure of viable cerebellar granule neurons to micromolar concentrations of hydrogen peroxide stimulates a prolonged Mrp1-mediated export of cellular GSH. This process may compromise the antioxidative potential of neurons and increase their sensitivity toward drugs and toxins. PMID:24524999

Hohnholt, Michaela C; Dringen, Ralf

2014-05-01

285

COMMENTS AND REPLIES: Comment on 'Late-time tails of a self-gravitating massless scalar field revisited'  

NASA Astrophysics Data System (ADS)

Bizo? et al (2009 Class. Quantum Grav. 26 175006) discuss the power-law tail in the long-time evolution of a spherically symmetric self-gravitating massless scalar field in odd spatial dimensions. They derive explicit expressions for the leading-order asymptotics for solutions with small initial data by using formal series expansions. Unfortunately, this approach misses an interesting observation that the actual decay rate is a product of asymptotic cancellations occurring due to a special structure of the nonlinear terms. Here, we show that one can calculate the leading asymptotics more directly by recognizing the special structure and cancellations already on the level of the wave equation.

Szpak, Nikodem

2009-12-01

286

Revisiting the impact of part-time work on adolescent adjustment: distinguishing between selection and socialization using propensity score matching.  

PubMed

The impact of part-time employment on adolescent functioning remains unclear because most studies fail to adequately control for differential selection into the workplace. The present study reanalyzes data from L. Steinberg, S. Fegley, and S. M. Dornbusch (1993) using multiple imputation, which minimizes bias in effect size estimation, and 2 types of propensity score matching, to account for selection effects. In this sample (N = 1,792; Grades 10-11, M = 16.26), youth who begin working more than 20 hr per week evince declines in school engagement and increases in substance use and delinquency compared with youth who remain unemployed. Conversely, working 20 hr or less a week has negligible effects, positive or negative, on academic, psychological, or behavioral outcomes. PMID:21291431

Monahan, Kathryn C; Lee, Joanna M; Steinberg, Laurence

2011-01-01

287

CCD time-series photometry of the globular cluster NGC 5053: RR Lyrae, Blue Stragglers and SX Phoenicis stars revisited  

NASA Astrophysics Data System (ADS)

We report the results of CCD V, r and I time-series photometry of the globular cluster NGC 5053. New times of maximum light are given for the eight known RR Lyrae stars in the field of our images, and their periods are revised. Their V light curves were Fourier decomposed to estimate their physical parameters. A discussion on the accuracy of the Fourier-based iron abundances, temperatures, masses and radii is given. New periods are found for the five known SX Phe stars, and a critical discussion of their secular period changes is offered. The mean iron abundance for the RR Lyrae stars is found to be [Fe/H] ~ -1.97 +/- 0.16 and lower values are not supported by the present analysis. The absolute magnitude calibrations of the RR Lyrae stars yield an average true distance modulus of 16.12 +/- 0.04 or a distance of 16.7 +/- 0.3 kpc. Comparison of the observational colour magnitude diagram (CMD) with theoretical isochrones indicates an age of 12.5 +/- 2.0 Gyr for the cluster. A careful identification of all reported blue stragglers (BS) and their V, I magnitudes leads to the conclusion that BS12, BS22, BS23 and BS24 are not BS. On the other hand, three new BS are reported. Variability was found in seven BS, very likely of the SX Phe type in five of them, and in one red giant star. The new SX Phe stars follow established Period-Luminosity relationships and indicate a distance in agreement with the distance from the RR Lyrae stars. Based on observations collected at the Indian Astrophysical Observatory, Hanle, India. E-mail: armando@astroscu.unam.mx (AAF); giridhar@iiap.res.in (SG); dan.bramich@hotmail.co.uk (DMB)

Arellano Ferro, A.; Giridhar, Sunetra; Bramich, D. M.

2010-02-01

288

Conditioning and time representation in long short-term memory networks.  

PubMed

Dopaminergic models based on the temporal-difference learning algorithm usually do not differentiate trace from delay conditioning. Instead, they use a fixed temporal representation of elapsed time since conditioned stimulus onset. Recently, a new model was proposed in which timing is learned within a long short-term memory (LSTM) artificial neural network representing the cerebral cortex (Rivest et al. in J Comput Neurosci 28(1):107-130, 2010). In this paper, that model's ability to reproduce and explain relevant data, as well as its ability to make interesting new predictions, are evaluated. The model reveals a strikingly different temporal representation between trace and delay conditioning since trace conditioning requires working memory to remember the past conditioned stimulus while delay conditioning does not. On the other hand, the model predicts no important difference in DA responses between those two conditions when trained on one conditioning paradigm and tested on the other. The model predicts that in trace conditioning, animal timing starts with the conditioned stimulus offset as opposed to its onset. In classical conditioning, it predicts that if the conditioned stimulus does not disappear after the reward, the animal may expect a second reward. Finally, the last simulation reveals that the buildup of activity of some units in the networks can adapt to new delays by adjusting their rate of integration. Most importantly, the paper shows that it is possible, with the proposed architecture, to acquire discharge patterns similar to those observed in dopaminergic neurons and in the cerebral cortex on those tasks simply by minimizing a predictive cost function. PMID:24258005

Rivest, Francois; Kalaska, John F; Bengio, Yoshua

2014-02-01

289

Real time dynamics of Si magic clusters mediating phase transformation: Si(111)-(1 × 1) to (7 × 7) reconstruction revisited  

NASA Astrophysics Data System (ADS)

Using Scanning Tunneling Microscope (STM), we show that the surface undergoes phase transformation from disordered "1 × 1" to (7 × 7) reconstruction which is mediated by the formation of Si magic clusters. Mono-disperse Si magic clusters of size ~ 13.5 ± 0.5 Å can be formed by heating the Si(111) surface to 1200 °C and quenching it to room temperature at cooling rates of at least 100 °C/min. The structure consists of 3 tetra-clusters of size ~ 4.5 ? similar to the Si magic clusters that were formed from Si adatoms deposited by Si solid source on Si(111)-(7 × 7) [1]. Using real time STM scanning to probe the surface at ~ 400 °C, we show that Si magic clusters pop up from the (1 × 1) surface and form spontaneously during the phase transformation. This is attributed to the difference in atomic density between "disordered 1 × 1" and (7 × 7) surface structures which lead to the release of excess Si atoms onto the surface as magic clusters.

Ong, Wei Jie; Tok, Eng Soon

2012-07-01

290

Loci affecting flowering time in oat under short-day conditions.  

PubMed

Flowering time (or days to heading) is an important characteristic in crop plants that affects adaptation to cropping cycles and growing seasons. The objectives of this study were to identify molecular markers associated with flowering time in 3 oat populations developed from Brazilian oat varieties, and to compare their map locations with those of other loci that might influence flowering time. Flowering time was studied in recombinant inbred lines from 3 hexaploid oat populations: UFRGS 8 x Pc68/5*Starter; UFRGS 881971 x Pc68/5*Starter; and UFRGS 8 x UFRGS 930605. Bulked segregant analysis, using amplified fragment length polymorphism, was followed by selective mapping in each population and in a reference population, 'Kanota' x 'Ogle' (KxO). One quantitative trait locus (QTL) with major effects on flowering time was identified in each cross. Comparative mapping showed that a major QTL, with earliness alleles originating from UFRGS 8 and UFRGS 881971, is in a region with close homology to KxO linkage group 17 and to a locus that reportedly confers day-length insensitivity in oat (Di1). This is the first report to identify the map location of the Di1 locus, and putatively confirm the presence of Di1 alleles in new germplasm. Further comparative mapping and the alignment of mapped oat markers with the sequenced rice genome suggest that this QTL and (or) Di1 is orthologous to the Hd1 locus in rice and the CONSTANS gene in Arabidopsis and other species. A different QTL with major effects segregated in the UFRGS 8 x UFRGS 930605 cross, where the early-flowering allele for Di1 was probably fixed. Two additional QTLs with smaller effects were identified in the UFRGS 8 x Pc68/5*Starter population. These results suggest that the Brazilian oat line UFRGS 8 contains an optimal set of alleles conditioning earliness under the short-day conditions of the Brazilian winter growing season, and that molecular selection could be used to introgress these alleles into other breeding material. PMID:17426767

Locatelli, Ana B; Federizzi, Luiz C; Milach, Sandra C K; Wight, Charlene P; Molnar, Stephen J; Chapados, Julie T; Tinker, Nicholas A

2006-12-01

291

2$\\\\,\\\\times\\\\,$ 25kV 50 Hz High-Speed Traction Power System: Short-Circuit Modeling  

Microsoft Academic Search

A2 25-kV 50 Hz traction power system was an- alyzed and modeled in the time domain in order to simulate short-circuit conditions and to attain a practical method to iden- tify the short circuit behavior of the traction system. In particular, due to the difficulty in assessing the track-line parameters which mainly depend on changing environmental conditions, the pos- sibility

Luigi Battistelli; Mario Pagano; Daniela Proto

2011-01-01

292

Circulation in Drake Passage revisited using new current time series and satellite altimetry: 1. The Yaghan Basin  

NASA Astrophysics Data System (ADS)

The complex bathymetry of the Drake Passage and the meridional extent of the Shackleton Fracture Zone, in particular, force the Subantarctic Front (SAF) and the Polar Front (PF) to veer to the north, and the flow of the Antarctic Circumpolar Current concentrates in the Yaghan Basin. We have studied the circulation in the Yaghan Basin, using 3 years of velocity data (January 2006-March 2009) at five mooring sites and 18 years of satellite altimetry data. Mean velocities at our mooring sites show a dominant eastward component which decreases with depth, as expected, with a notable exception in the center of the Yaghan Basin, where mean velocities reveal a dominant westward component increasing with depth. The mooring data suggest the existence of a permanent, strong deep cyclonic circulation over the Yaghan seafloor depression in the northeastern part of the Yaghan Basin. The in situ data provide the first opportunity to compare altimetry-derived velocities with high temporal resolution near-surface current meter velocities in a large eddy kinetic energy environment at high latitudes. Globally, altimetry-derived velocities compare rather well with the in situ velocities at 500 m depth both in strength and direction. Correlations are high between the in situ velocities and the surface velocities derived from satellite altimetric data. Mean sea level estimates lead to reasonable mean surface velocities with, however, a slight underestimation of the mean velocity at the mean location of the SAF on the continental slope and a more important underestimation of the westward current in the center of the Yaghan Basin. A dominant mode of velocity variations (23% of the variance) is observed both in the in situ and satellite data, corresponding to a strong southward meander of the SAF upstream of the mooring line and a northward meander of the PF downstream of the latter. The 18 yearlong altimetry time series shows that the mode is robust and has a strong semiannual component.

Ferrari, Ramiro; Provost, Christine; Renault, Alice; SennéChael, Nathalie; Barré, Nicolas; Park, Young-Hyang; Lee, Jae Hak

2012-12-01

293

An Electronic Circuit System for Time-Reversal of Ultra-Wideband Short Impulses Based on Frequency-Domain Approach  

Microsoft Academic Search

In this paper, a compact and low-cost electronic circuit system is designed for time-reversal of ultra-wideband short impulses (with nanosecond and sub-nanosecond temporal durations). A frequency-domain approach is adopted to avoid high sampling rate in time. Specifically, the proposed system obtains the discrete spectra of input impulses first; then realizes time-reversal in frequency domain; and finally synthesizes the time-reversed impulses

Huiqing Zhai; Shaoshu Sha; Varun K. Shenoy; Sungyong Jung; Mingyu Lu; Kyoungwon Min; Sungchul Lee; Dong S. Ha

2010-01-01

294

Java-based framework for processing and displaying short-echo-time magnetic resonance spectroscopy signals.  

PubMed

Magnetic resonance spectroscopy (MRS) can be used to determine in a non-invasive way the concentrations of certain chemical substances, also called metabolites. The spectra of MRS signals contain peaks that correspond to the metabolites of interest. Short-echo-time signals are characterized by heavily overlapping metabolite peaks and require sophisticated processing methods. To be useful in a clinical environment tools are needed that can process those signals in an accurate and fast way. Therefore, we developed novel processing methods and we designed a freely available and open-source framework (http://www.esat.kuleuven.ac.be/sista/members/biomed) in which the processing methods can be integrated. The framework has a set of abstract classes, called hot spots, and its goal is to provide a general structure and determine the control flow of the program. It provides building blocks or components in order to help developers with integrating their methods in the framework via a plug-in system. The framework is designed with the unified modeling language (UML) and implemented in Java. When a developer implements the framework he gets an application that acts like a simple and user-friendly graphical user interface (GUI) for processing MRS data. This article describes in detail the structure and implementation of the framework and the integration of our processing methods in it. PMID:17174003

De Neuter, B; Luts, J; Vanhamme, L; Lemmerling, P; Van Huffel, S

2007-02-01

295

Application of MOSFET Detectors for Dosimetry in Small Animal Radiography Using Short Exposure Times  

PubMed Central

Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies.

De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G. Allan; Yoshizumi, Terry T.

2008-01-01

296

Application of MOSFET detectors for dosimetry in small animal radiography using short exposure times.  

PubMed

Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies. PMID:18666818

De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G Allan; Yoshizumi, Terry T

2008-08-01

297

The wide-angle equation and its solution through the short-time iterative Lanczos method.  

PubMed

Properties of the wide-angle equation (WAEQ), a nonparaxial scalar wave equation used to propagate light through media characterized by inhomogeneous refractive-index profiles, are studied. In particular, it is shown that the WAEQ is not equivalent to the more complicated but more fundamental Helmholtz equation (HEQ) when the index of refraction profile depends on the position along the propagation axis. This includes all nonstraight waveguides. To study the quality of the WAEQ approximation, we present a novel method for computing solutions to the WAEQ. This method, based on a short-time iterative Lanczos (SIL) algorithm, can be applied directly to the full three-dimensional case, i.e., systems consisting of the propagation axis coordinate and two transverse coordinates. Furthermore, the SIL method avoids series-expansion procedures (e.g., Padé approximants) and thus convergence problems associated with such procedures. Detailed comparisons of solutions to the HEQ, WAEQ, and the paraxial equation (PEQ) are presented for two cases in which numerically exact solutions to the HEQ can be obtained by independent analysis, namely, (i) propagation in a uniform dielectric medium and (ii) propagation along a straight waveguide that has been tilted at an angle to the propagation axis. The quality of WAEQ and PEQ, compared with exact HEQ results, is investigated. Cases are found for which the WAEQ actually performs worse than the PEQ. PMID:12665105

Campos-Martínez, José; Coalson, Rob D

2003-03-20

298

Short-time rheology and diffusion in suspensions of Yukawa-type colloidal particles  

NASA Astrophysics Data System (ADS)

A comprehensive study is presented on the short-time dynamics in suspensions of charged colloidal spheres. The explored parameter space covers the major part of the fluid-state regime, with colloid concentrations extending up to the freezing transition. The particles are assumed to interact directly by a hard-core plus screened Coulomb potential, and indirectly by solvent-mediated hydrodynamic interactions. By comparison with accurate accelerated Stokesian Dynamics (ASD) simulations of the hydrodynamic function H(q), and the high-frequency viscosity ??, we investigate the accuracy of two fast and easy-to-implement analytical schemes. The first scheme, referred to as the pairwise additive (PA) scheme, uses exact two-body hydrodynamic mobility tensors. It is in good agreement with the ASD simulations of H(q) and ??, for smaller volume fractions up to about 10% and 20%, respectively. The second scheme is a hybrid method combining the virtues of the ?? scheme by Beenakker and Mazur with those of the PA scheme. It leads to predictions in good agreement with the simulation data, for all considered concentrations, combining thus precision with computational efficiency. The hybrid method is used to test the accuracy of a generalized Stokes-Einstein (GSE) relation proposed by Kholodenko and Douglas, showing its severe violation in low salinity systems. For hard spheres, however, this GSE relation applies decently well.

Heinen, Marco; Banchio, Adolfo J.; Nägele, Gerhard

2011-10-01

299

The influence of alcoholic intoxication on the short-time energy function of speech.  

PubMed

This study investigates rhythmic features based on the short-time energy function of speech signals with the aim of finding robust, speaker-independent features that indicate speaker intoxication. Data from the German Alcohol Language Corpus, which comprises read, spontaneous, and command&control speech uttered by 162 speakers of both genders and various age groups when sober and intoxicated, were analyzed. Energy contours are compared directly (Root Mean Squared Error, statistical correlation, or the Euclidean distance in the spectral space of the contour) and by parameterization of the contour using the Discrete Cosine Transform (DCT) and the first and second moments of the lower DCT spectrum. Contours are also analyzed by Principal Components Analysis aiming at fundamental "eigen contour" changes that might encode intoxication. Energy contours differ significantly with intoxication in terms of distance measures, the second and fourth DCT coefficients, and the first and second moments of the lower DCT spectrum. Principal Components Analysis did not yield interpretable "eigen contours" that could be used in distinguishing intoxicated from sober contours. PMID:24815274

Heinrich, Christian; Schiel, Florian

2014-05-01

300

Zipf's Law in Short-Time Timbral Codings of Speech, Music, and Environmental Sound Signals  

PubMed Central

Timbre is a key perceptual feature that allows discrimination between different sounds. Timbral sensations are highly dependent on the temporal evolution of the power spectrum of an audio signal. In order to quantitatively characterize such sensations, the shape of the power spectrum has to be encoded in a way that preserves certain physical and perceptual properties. Therefore, it is common practice to encode short-time power spectra using psychoacoustical frequency scales. In this paper, we study and characterize the statistical properties of such encodings, here called timbral code-words. In particular, we report on rank-frequency distributions of timbral code-words extracted from 740 hours of audio coming from disparate sources such as speech, music, and environmental sounds. Analogously to text corpora, we find a heavy-tailed Zipfian distribution with exponent close to one. Importantly, this distribution is found independently of different encoding decisions and regardless of the audio source. Further analysis on the intrinsic characteristics of most and least frequent code-words reveals that the most frequent code-words tend to have a more homogeneous structure. We also find that speech and music databases have specific, distinctive code-words while, in the case of the environmental sounds, this database-specific code-words are not present. Finally, we find that a Yule-Simon process with memory provides a reasonable quantitative approximation for our data, suggesting the existence of a common simple generative mechanism for all considered sound sources.

Haro, Martin; Serra, Joan; Herrera, Perfecto; Corral, Alvaro

2012-01-01

301

Response Time Measurements in Short-Wave Infrared HgCdTe e-APDs  

NASA Astrophysics Data System (ADS)

The impulse response time has been measured as a function of reverse bias, gain, and temperature in backside-illuminated short-wave infrared HgCdTe avalanche photodiodes (APDs) with variable junction geometry. The APD geometry was altered using HgCdTe substrates of variable thickness and by variation of device fabrication parameters. This approach allowed study of the drift-diffusion dynamics of the electrons before entering the junction and the electron and hole dynamics during the junction transition in APDs with different carrier collection distances and junction widths. The response time was typically limited by a double exponential decay, which is attributed to contributions from the impedance mismatch between the interconnection circuit and the 50-? radiofrequency probe, and a delayed diffusion response from carriers generated far from the junction. These contributions limited the maximum bandwidth of the diodes to about 600 MHz, independently of gain and temperature. The hot carrier velocities are estimated by fitting the measured response with numerical calculations, taking into account contributions from a direct drift-multiplication response and a delayed diffusion response. This analysis shows that the hot carrier dynamics is close to independent of temperature and that the electron drift velocity saturates at the gain onset to a value of 1 × 107 cm/s, decreasing upon a further increase of the electric field E to a value of about 3 × 106 cm/s at E = 100 kV/cm. The hole velocity shows a slow variation from 3 × 106 cm/s at low electric fields to 1.5 × 106 cm/s at high electric fields.

Rothman, Johan; Foubert, Kevin; Lasfargues, Gilles; Largeron, Christophe

2014-05-01

302

Ossiculoplasty: revisited.  

PubMed

Conductive hearing loss from ossicular chain abnormalities may result from either discontinuity or fixation of the ossicular chain. The ideal prosthesis for ossicular reconstruction should be biocompatible, stable, safe, readily available, and capable of yielding optimal sound transmission. At present ossiculoplasty techniques using alloplast materials are becoming popular but the fate of these synthetic materials in human middle ear requires further study. Autologous ossicle or cortical bone grafts maintain their morphologic contour, size, shape, and physical integrity for long periods of time, over 25 years making them still the choice at present. The choice of technique will still depend on the causative pathology, availability of graft, surgical experience. PMID:24427696

Mudhol, R S; Naragund, A I; Shruthi, V S

2013-12-01

303

Time to revisit polyphasic taxonomy.  

PubMed

Although the International Code of Nomenclature of Bacteria does not specify a working strategy, editors and reviewers of taxonomic journals commonly request a polyphasic taxonomic approach that includes phenotypic, genotypic and chemotaxonomic information for the description of novel bacterial species. Whole genome sequences provide an insight into the genetic nature of microbial species, yield new and superior tools for delineating bacterial species and for studying their phylogeny, and provide a window on an organism's metabolic potential. These new insights and tools are gradually introduced in the polyphasic taxonomic practice. The genus Burkholderia, a controversial group of bacteria with both benign and devastating characteristics, is used as an example to show that the modern practice of polyphasic taxonomy is counterproductive in light of the tremendous number of bacterial species that awaits formal description and naming. Bacterial taxonomists must urgently reconsider how to describe and name novel bacteria in the genomic era, and should consider using a full genome sequence and a minimal description of phenotypic characteristics as a basic, sufficient, cost-effective and appropriate biological identity card for a species description. PMID:24633913

Vandamme, Peter; Peeters, Charlotte

2014-07-01

304

Classification of brain tumours using short echo time 1H MR spectra.  

PubMed

The purpose was to objectively compare the application of several techniques and the use of several input features for brain tumour classification using Magnetic Resonance Spectroscopy (MRS). Short echo time 1H MRS signals from patients with glioblastomas (n = 87), meningiomas (n = 57), metastases (n = 39), and astrocytomas grade II (n = 22) were provided by six centres in the European Union funded INTERPRET project. Linear discriminant analysis, least squares support vector machines (LS-SVM) with a linear kernel and LS-SVM with radial basis function kernel were applied and evaluated over 100 stratified random splittings of the dataset into training and test sets. The area under the receiver operating characteristic curve (AUC) was used to measure the performance of binary classifiers, while the percentage of correct classifications was used to evaluate the multiclass classifiers. The influence of several factors on the classification performance has been tested: L2- vs. water normalization, magnitude vs. real spectra and baseline correction. The effect of input feature reduction was also investigated by using only the selected frequency regions containing the most discriminatory information, and peak integrated values. Using L2-normalized complete spectra the automated binary classifiers reached a mean test AUC of more than 0.95, except for glioblastomas vs. metastases. Similar results were obtained for all classification techniques and input features except for water normalized spectra, where classification performance was lower. This indicates that data acquisition and processing can be simplified for classification purposes, excluding the need for separate water signal acquisition, baseline correction or phasing. PMID:15324770

Devos, A; Lukas, L; Suykens, J A K; Vanhamme, L; Tate, A R; Howe, F A; Majós, C; Moreno-Torres, A; van der Graaf, M; Arús, C; Van Huffel, S

2004-09-01

305

Classification of brain tumours using short echo time 1H MR spectra  

NASA Astrophysics Data System (ADS)

The purpose was to objectively compare the application of several techniques and the use of several input features for brain tumour classification using Magnetic Resonance Spectroscopy (MRS). Short echo time 1H MRS signals from patients with glioblastomas ( n = 87), meningiomas ( n = 57), metastases ( n = 39), and astrocytomas grade II ( n = 22) were provided by six centres in the European Union funded INTERPRET project. Linear discriminant analysis, least squares support vector machines (LS-SVM) with a linear kernel and LS-SVM with radial basis function kernel were applied and evaluated over 100 stratified random splittings of the dataset into training and test sets. The area under the receiver operating characteristic curve (AUC) was used to measure the performance of binary classifiers, while the percentage of correct classifications was used to evaluate the multiclass classifiers. The influence of several factors on the classification performance has been tested: L2- vs. water normalization, magnitude vs. real spectra and baseline correction. The effect of input feature reduction was also investigated by using only the selected frequency regions containing the most discriminatory information, and peak integrated values. Using L2-normalized complete spectra the automated binary classifiers reached a mean test AUC of more than 0.95, except for glioblastomas vs. metastases. Similar results were obtained for all classification techniques and input features except for water normalized spectra, where classification performance was lower. This indicates that data acquisition and processing can be simplified for classification purposes, excluding the need for separate water signal acquisition, baseline correction or phasing.

Devos, A.; Lukas, L.; Suykens, J. A. K.; Vanhamme, L.; Tate, A. R.; Howe, F. A.; Majós, C.; Moreno-Torres, A.; van der Graaf, M.; Arús, C.; Van Huffel, S.

2004-09-01

306

Short-time glucose exposure of embryonic carcinoma cells impairs their function as terminally differentiated cardiomyocytes.  

PubMed

The fetal and postnatal phenotype is influenced by developmental conditions experienced prenatally. Among prenatal development metabolic factors are of particular importance as they are supposed to predispose for pathophysiological alterations later in life and to pioneer functional impairment in senescence (metabolic programming). Till now the mechanisms of metabolic programming are not well understood. We have investigated various concentrations of glucose during differentiation of pluripotent P19 embryonic carcinoma cells (ECC) into cardiomyocytes. Undifferentiated P19 cells were exposed to 5mM (low), 25 mM (control), 40 mM or 100mM (high) glucose for 48 h during embryoid body (EB) formation, followed by plating and differentiation into cardiomyocytes in vitro with standard glucose supplementation (25 mM) for 10-15 days. The amount of cardiac clusters, the frequency of spontaneous beatings as well as the expression of metabolic and cardiac marker genes and their promoter methylation were measured. We observed a metabolic programming effect of glucose during cardiac differentiation. Whereas the number of beating clusters and the expression of the cardiac marker alpha myosin heavy chain (?-MHC) were comparable in all groups, the frequencies of beating clusters were significantly higher in the high glucose group compared to low glucose. However, neither the insulin receptor (IR) or insulin like growth factor 1 receptor (IGF1R) nor the metabolic gene glucose transporter 4 (GLUT4) were influenced in RNA expression or in promoter methylation. Our data indicate that a short time glucose stress during embryonic cell determination leads to lasting effects in terminally differentiated cell function. PMID:22405827

Knelangen, Julia M; Kurz, Randy; Schagdarsurengin, Undraga; Fischer, Bernd; Navarrete Santos, Anne

2012-04-01

307

A coordinated approach for real-time short term hydro scheduling  

SciTech Connect

The paper describes a coordinated approach to short-term hydro scheduling and dispatch that has been developed as a part of the Tasmanian Hydro Electric Commission`s (HEC) new Energy Management System (EMS), which is being delivered by Landis and Gyr Energy Management. Tasmania`s hydro generation system consists of 40 reservoirs in six river catchments. The daily water release for each plant is scheduled using the HEC`s mid-term operation policy. The Hydro Scheduling and Commitment (HSC) function schedules the hydro units on a half hourly basis so that the allocated water release maximizes the energy production. This maximization of energy production is achieved by maximizing the head and this ensures that operation is always as close as possible to maximum efficiency. Mixed Integer Linear Programming is used with a detailed model of the interconnected hydro system to determine the half-hourly operation schedule. The Hydro Economic Dispatch (HED) function is used to implement the schedules produced by HSC in the real-time operation. The HED also uses a detailed model of the hydro system with a Linear Programming algorithm to ensure that each unit operates as close as possible to its head-dependent theoretical maximum efficiency point while meeting the desired storage levels specified by the HSC solution. HSC and HED have been tested against a number of operational scenarios and when it is fully integrated within the new EMS it is expected to yield annual stored energy savings up to 0.5% through more efficient hydro-electric system operation. It is expected to also provide additional savings by fostering improvements to the mid-term operating plan.

Tufegdzic, N. [Hydro Electric Commission, Hobart (Australia)] [Hydro Electric Commission, Hobart (Australia); Frowd, R.J. [Landis and Gyr Energy Management, San Jose, CA (United States)] [Landis and Gyr Energy Management, San Jose, CA (United States); Stadlin, W.O. [Macro Corp., Horsham, PA (United States)] [Macro Corp., Horsham, PA (United States)

1996-11-01

308

Short contact time direct coal liquefaction using a novel batch reactor. Quarterly report, May 15, 1995--September 15, 1995  

SciTech Connect

The objective of this research is to optimize the design and operation of the bench scale batch reactor for coal liquefaction at short contact times (0.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction, particularly at short reaction times, and to investigate the role of the organic oxygen components of coal and their reaction pathways during liquefaction. This quarterly report covers the status of progress toward these objectives. 3 refs., 14 figs., 2 tabs.

Klein, M.T.; Calkins, W.H.; Huang, He

1995-10-05

309

Palatogram revisited.  

PubMed

It is the responsibility of the dentist to fabricate a denture that is fully functional and perfectly esthetic. One prime oral function that has always been overlooked in this regard is speech. It has been thought that speech will follow mere replacement of teeth and that it is the patient's duty to fine tune this function with practice. Phonetics, esthetics, function and comfort form the foundation of a successful prosthodontic treatment. Accurate approximation of palatal contours of a maxillary complete denture to a patient's tongue can improve speech intelligibility, if other factors such as tooth position, occlusal plane and occlusal vertical dimension are satisfactory. Customizing palatal contours of a maxillary complete denture can be accomplished by using tissue-conditioning material, which provides sufficient working time for a patient to pronounce a series of sibilant sounds while recording dynamic impression of the tongue. This article describes a technique of obtaining palatogram and customizing palatal contours of a maxillary complete denture with autopolymerizing acrylic resin to improve the intelligibility of speech. PMID:24808716

Jain, Ashish R; Venkat Prasad, M K; Ariga, Padma

2014-01-01

310

Palatogram revisited  

PubMed Central

It is the responsibility of the dentist to fabricate a denture that is fully functional and perfectly esthetic. One prime oral function that has always been overlooked in this regard is speech. It has been thought that speech will follow mere replacement of teeth and that it is the patient's duty to fine tune this function with practice. Phonetics, esthetics, function and comfort form the foundation of a successful prosthodontic treatment. Accurate approximation of palatal contours of a maxillary complete denture to a patient's tongue can improve speech intelligibility, if other factors such as tooth position, occlusal plane and occlusal vertical dimension are satisfactory. Customizing palatal contours of a maxillary complete denture can be accomplished by using tissue-conditioning material, which provides sufficient working time for a patient to pronounce a series of sibilant sounds while recording dynamic impression of the tongue. This article describes a technique of obtaining palatogram and customizing palatal contours of a maxillary complete denture with autopolymerizing acrylic resin to improve the intelligibility of speech.

Jain, Ashish R.; Venkat Prasad, M. K.; Ariga, Padma

2014-01-01

311

Amyoplasia revisited.  

PubMed

Amyoplasia is a specific type and the most common form of arthrogryposis (multiple congenital contractures). It is a clinical diagnosis at this time. Care should be used making the diagnosis because of the implications for recurrence, natural history, associated anomalies, and both etiology and pathogenesis. We reviewed over 600 published reports and 2,500 individual records to identify the 560 individuals reported here. Affected limbs had characteristic positions with fatty-fibrous replacement of muscle. Upper limb involvement was usually characterized by extended elbows. Lower limbs were held in various positions at birth; however, equinovarus positioning of feet was almost always present. Symmetric involvement was common. Among 560 affected individuals, subtypes were identified: four-limb symmetric involvement (331/560 = 55.9%), severe involvement (41/560 = 7.3%), three-limb involvement (27/560 = 4.8%), upper limb only Amyoplasia (ULA; 94/560 = 16.8%), and lower limb only Amyoplasia (LLA; 25/560 = 15.5%). Discordant monozygotic twinning was increased, occurring in 6.6% (37/560; OR 10.9). A variety of additional anomalies were seen, attributed to apparent vascular compromise. Gastrointestinal vascular compromise-type anomalies were present in 9.1% (51/560), trunk muscle defects in another 2.7% (15/560), digit compromise in 12.1% (68/560), constriction rings in 4.3% (24/560), and perinatal long bone fractures in 10.5% (59/560). Although prenatal ultrasound became the standard of care in 1990, only about one quarter of affected pregnancies were diagnosed prenatally since 1990. Amyoplasia appears to be completely sporadic. Novel pathogenetic mechanisms for the congenital anomalies seen in Amyoplasia need to be identified. PMID:24459070

Hall, Judith G; Aldinger, Kimberly A; Tanaka, Kimi I

2014-03-01

312

Estimating return periods of extreme values from relatively short time series of winds  

NASA Astrophysics Data System (ADS)

An important factor for determining the prospect of individual wind farm sites is the frequency of extreme winds at hub height. Here, extreme winds are defined as the value of the highest 10 minutes averaged wind speed with a 50 year return period, i.e. annual exceeding probability of 2% (Rodrigo, 2010). A frequently applied method to estimate winds in the lowest few hundred meters above ground is to extrapolate observed 10-meter winds logarithmically to higher altitudes. Recent study by Drechsel et al. (2012) showed however that this methodology is not as accurate as interpolating simulated results from the global ECMWF numerical weather prediction (NWP) model to the desired height. Observations of persistent low level jets near Colima in SW-Mexico also show that the logarithmic approach can give highly inaccurate results for some regions (Arfeuille et al., 2012). To address these shortcomings of limited, and/or poorly representative, observations and extrapolations of winds one can use NWP models to dynamically scale down relatively coarse resolution atmospheric analysis. In the case of limited computing resources one has typically to make a compromise between spatial resolution and the duration of the simulated period, both of which can limit the quality of the wind farm siting. A common method to estimate maximum winds is to fit an extreme value distribution (e.g. Gumbel, gev or Pareto) to the maximum values of each year of available data, or the tail of these values. If data are only available for a short period, e.g. 10 or 15 years, then this will give a rather inaccurate estimate. It is possible to deal with this problem by utilizing monthly or weekly maxima, but this introduces new problems: seasonal variation, autocorrelation of neighboring values, and increased discrepancy between data and fitted distribution. We introduce a new method to estimate return periods of extreme values of winds at hub height from relatively short time series of winds, simulated at a high spatial resolution. REFERENCES Arfeuille, Gilles J. M., A. L. Quintanilla, L. Zizumbo, and F. C. Viesca, 2012. Wind Resource Assessment in a Tropical Region with Complex Terrain using SODAR and a Meteorological Tower Network to Measure Low Level Jets and Boundary Layer Conditions. 15th AMS Conference on Mountain Meteorology, Steam boat Spring, Colorado, USA, August 2012. Available on-line: https://ams.confex.com/ams/15MountMet/webprogram/Manuscript/Paper210184/ARFEUILLLE_etal_15MountMet Conf_Aug2012.pdf Drechsel S., G. J. Mayr, J. W. Messner, and R. Stauffer, 2012: Wind Speeds at Heights Crucial for Wind Energy: Measurements and Verification of Forecasts. J. Appl. Meteor. Climatol., 51, 1602-1617. Rodrigo, J. S., 2010. State-of-the-Art of Wind Resource Assessment. CENER National Renewable Energy Center, Sarriguren, Spain. Available on-line: http://www.waudit-itn.eu/download.php?id=103&parent=79

Jonasson, Kristjan; Agustsson, Halfdan; Rognvaldsson, Olafur; Arfeuille, Gilles

2013-04-01

313

Short contact time direct coal liquefaction using a novel batch reactor. Progress report, September 27, 1993--December 31, 1993.  

National Technical Information Service (NTIS)

The objective for this research is to optimize the design and operation of the bench scale batch reactor (STBR) for coat liquefaction at short contact times (0.01 to 10 minutes). This reactor is simple and low enough in cost to serve as a suitable replace...

M. T. Klein W. H. Calkins

1994-01-01

314

Presentation Time and Proactive Interference in the Short-Term Memory for Consonant Units of Varying Sizes.  

National Technical Information Service (NTIS)

Two experiments are reported with respect to the short-term memory for consonant units varying in size. Methods were used such that time to read each unit was adequate and such that retention could be measured without PI. At all of the retention intervals...

C. N. Cofer E. H. Davidson

1965-01-01

315

Short-time dynamic signature of the liquid-crystal-glass transition in a suspension of charged spherical colloids.  

PubMed

In this paper, the dynamic transition of the liquid-crystal-glass transition is investigated by dynamic light scattering, DLS. From the intensity autocorrelation function, g2(q, t), the short-time dynamic function, D(q), has been determined at different concentrations in both the crystal and glass regions. From D(q), the short-time self-diffusion, ds, was determined. ds speeds up in the crystal state but has very similar characteristics in the liquid and the glass region. The general model in which the colloidal crystallization transition in a spherical colloidal system is driven by an increase in local entropy is also verified by relating ds to the local excess entropy. Experimentally determined structure factors, S(q), are also discussed, and we show the similarity between the glass and the liquid. This investigation shows that the liquid-crystal transition can be identified in addition to the appearance of Bragg peaks with a short-time dynamic transition while no sharp transition in the short-time dynamics or S(q) can be found between the glass and the liquid. PMID:24867228

Holmqvist, P

2014-06-17

316

Effects of the Coordination Exercise Program on School Children's Agility: Short-Time Program during School Recess  

ERIC Educational Resources Information Center

This study examined the impact of a short-time coordination program conducted during recess periods on improving agility in elementary school students. The subjects consisted of 60 third grade students, who were randomly assigned to an experimental group (n = 29) and a control group (n = 31). The experimental group completed a coordination program…

Yasumitsu, Tatsuo; Nogawa, Haruo; Hatano, Yoshiro

2011-01-01

317

Experimental Demonstration of Violations of the Second Law of Thermodynamics for Small Systems and Short Time Scales  

Microsoft Academic Search

We experimentally demonstrate the fluctuation theorem, which predicts appreciable and measurable violations of the second law of thermodynamics for small systems over short time scales, by following the trajectory of a colloidal particle captured in an optical trap that is translated relative to surrounding water molecules. From each particle trajectory, we calculate the entropy production\\/consumption over the duration of the

G. M. Wang; E. M. Sevick; Emil Mittag; Debra J. Searles; Denis J. Evans

2002-01-01

318

Validity and Time Savings in the Selection of Short Forms of the Wechsler Adult Intelligence Scale--Revised.  

ERIC Educational Resources Information Center

Validity and reliability were calculated from data in the standardization sample of the Wechsler Adult Intelligence Scale--Revised for 565 proposed short forms. Time saved in comparison with use of the long form was estimated. The most efficient combinations were generally those composed of subtests that were quick to administer. (SLD)

Ward, L. Charles; Ryan, Joseph J.

1996-01-01

319

Short time-scale analysis of the NW Mediterranean ecosystem during summer–autumn transition: A 1D modelling approach  

Microsoft Academic Search

Modelling was used as a tool to better understand the physical and biological processes observed during the multidisciplinary cruise DYNAPROC 2 (DYNAmic of rapid PROCesses in the water column), which took place in the Ligurian Sea in September–October 2004. The aim of the cruise was to study the short time-scale physical and biological processes that occur when the ecosystem switches

V. Raybaud; P. Nival; L. Prieur

2011-01-01

320

Body-Condition Indices Are Repeatable across Short, but Not Long, Time Periods in Crimson Finches Neochmia phaeton.  

PubMed

Abstract It is common in evolutionary ecology to interpret body-condition indices as indicators of individual quality, but this hypothesized relationship has been questioned and remains poorly validated. Here, we test one of the fundamental predictions of this condition-quality hypothesis, that relative-condition indices are repeatable within individuals, that is, that the index score of an individual relative to others is consistent over time. We sampled crimson finches (Neochmia phaeton) for seven commonly used condition indices and tested whether individual condition relative to conspecifics in the same context (e.g., breeding stage) was repeatable. We calculated the relative indices' repeatability across several temporal scales, from short (within breeding season) to long (more than 2 yr) time periods, as well as without consideration of timescale. Most relative-condition indices were repeatable when sampled without consideration of timescale, all were repeatable within a short time period, and none were repeatable over the longest time period. This provides only partial support for the condition-quality hypothesis, because although relative-condition indices were generally repeatable, this was primarily attributed to short-term, instead of long-term, repeatability. Condition indices may be meaningful indicators of short-term survival or fitness potential, but our findings are inconsistent with the idea that condition indices are indicators of inherent individual quality. PMID:24940919

Milenkaya, O; Legge, S; Walters, J R

2014-01-01

321

Short Time Lyapounov Indicators in the Case of a Sun-Jupiter-Saturn-Asteroid System  

NASA Astrophysics Data System (ADS)

In our previous papers (Sandor et al., 1999a; Sandor et al., 1999b) we have discussed the application of the short time indicators in the planar circular Restricted Three Body Problem (RTBP) and in the Elliptic Restricted Three-Body problem (ERTBP) in order to distinguish between chaotic and regular domains of the phase space in theese problems. The method of stretching numbers was introduced by Voglis and Contopoulos (1994). This method allows a quick distinction between ordered and chaotic regions. We also applied the method of stretching numbers to the elliptic restricted three-body problem. As an extension of our investigation, in the present paper we apply the method of stretching numbers to a realistic Sun-Jupiter-Saturn-Asteroid (SJSA) problem. We represent the structure of the phase-space in the a-e plane, where a is the semimajor axis and e is the eccentricity. For an individual N curve, where N is the average value of stretching numbers. The values of the semimajor axis has been taken from the interval [3.2,5.2] (AU) for a fixed value of the eccentricity of the test particle between e=0 and e=0.4. For a good visualization of the regular and chaotic regions in the a-e plane we have processed the curves of average values calculating the absolut value of their ``derivative'' |frac {Delta N}{Delta a}|, where Delta a = a_{i+1}-ai is the difference between two consecutive initial semimajor axis and Delta N is the corresponding change of the average value of stretching numbers. If this derivative is larger than a certain value (in our case 0.002), the corresponding region between two neighbouring initial conditions is classified as chaotic. The usefulness of this method is based on the very fast and effective way how it approximates the location and size of the regular and chaotic regions. We have found that the structure of the phase-space is very similar in the RTBP and in the ERTB but there is a significant difference in the case of the SJSA. The grant OTKA F030147 of the National Research Foundation is acknowledged.

Balla, R. F.; Sandor, Zs.

1999-09-01

322

Investigating oceanic tidal energy dissipation on deep time scales using short tidal deposit sequences  

NASA Astrophysics Data System (ADS)

One of the enduring problems in physical oceanography has been that of tidal dynamics and the effective tidal torque that serves to slow Earth's axial rotation. In the late 20th century, with the aid of satellite altimetry and other technologies, a suite of reliable estimates was finally placed on the magnitude of this torque and other, related parameters in the current epoch. Tidal drag accounts for a 20 microsecond/year increase in mean day length, a 3.5 terawatt dissipation of energy in the oceans (Kantha et al., 1998), and a lunar retreat rate of 3.82 cm/yr (Dickey et al., 1994). Despite these significant advances, however, the problem of tidal dissipation in the geologic past remains largely unresolved. This is due, in part, to difficulties in numerical modeling of past tidal regimes that stem from uncertainties in ocean basin configurations and lunar distances. Tidal deposits can record, to high resolution, the primary astronomical periodicities responsible for the generation of the tidal currents under which transport and deposition occur. With reliable lunar orbital period data obtained from tidal deposits, the past Earth-Moon distance and length of day can be calculated. This task requires careful spectral analysis and consideration of sedimentological factors that may add noise and/or discontinuities to the signal. For deposits representing less than one year of deposition, the necessary assumptions are that Earth's moment of inertia has not changed significantly over the time interval of interest and that the solar component of tidal dissipation can be well-approximated. With consideration of the total angular momentum of the Earth-Moon couplet, we derive a method to calculate lunar distance and length of day. The efficacy of this method and its assumptions is tested via the multi-year sequence of data obtained from the late Precambrian Elatina Formation of Australia and comparing results obtained from the full suite of data by Williams (2000). We go on to analyze a short (3.5 month) Carboniferous dataset from the Abbott Formation of the Illinois Basin, USA. The results suggest non-linearity in ocean tidal dissipation since the late Precambrian and an average lunar retreat rate since the Carbiniferous below the present value, despite a larger lunar distance. With more tidal deposit data analyzed in this way, a much more complete picture of dissipation and Earth-Moon evolution could be realized.

Coughenour, C.

2012-12-01

323

Short-time asymptotics of a rigorous path integral for N = 1 supersymmetric quantum mechanics on a Riemannian manifold  

NASA Astrophysics Data System (ADS)

Following Feynman's prescription for constructing a path integral representation of the propagator of a quantum theory, a short-time approximation to the propagator for imaginary-time, N = 1 supersymmetric quantum mechanics on a compact, even-dimensional Riemannian manifold is constructed. The path integral is interpreted as the limit of products, determined by a partition of a finite time interval, of this approximate propagator. The limit under refinements of the partition is shown to converge uniformly to the heat kernel for the Laplace-de Rham operator on forms. A version of the steepest descent approximation to the path integral is obtained, and shown to give the expected short-time behavior of the supertrace of the heat kernel.

Fine, Dana S.; Sawin, Stephen

2014-06-01

324

Time Perspective and Identity Formation: Short-Term Longitudinal Dynamics in College Students  

ERIC Educational Resources Information Center

Planning for the future and developing a personalized identity are conceived of as important developmental tasks that adolescents and emerging adults are confronted with on the pathway to adulthood. The present study set out to examine whether both tasks develop in tandem by using a short-term longitudinal dataset consisting of 371 college…

Luyckx, Koen; Lens, Willy; Smits, Ilse; Goossens, Luc

2010-01-01

325

Short-term forecasting of travel time based on license plate matching data  

Microsoft Academic Search

In this paper, we review the state of art of short-term traffic forecasting models, outlining their basic ideas, related works, advantages and disadvantages of each model. An improved adaptive exponential smoothing (IAES) model is also proposed to overcome the drawbacks of previous adaptive exponential smoothing model. Then comparing experiments are carried out under normal traffic condition and abnormal traffic condition

Zhipeng Li; Nan Li; Fuqiang Liu; Yuncai Liu

2008-01-01

326

Frequency analysis of noisy short-time stationary signals using filter-diagonalization  

Microsoft Academic Search

Spectral reconstruction of short signals is a problem relevant to many areas of engineering and science. Classical techniques, e.g. Fourier transform (FT) and the wavelet transform (WT) fail to provide accurate estimates of the low frequency content of the signal due to the inherent limitations formulated by the Heisenberg uncertainty principle. To cope with the problem this paper brings up

Uros Benko; Dani Juricic

2008-01-01

327

The Well of Time. Eighteen Short Stories from Philippine Contemporary Literature.  

ERIC Educational Resources Information Center

A collection of eighteen short stories by Filipino writers is presented. The selections represent a variety of images of Filipino culture, both urban and rural, and life styles in northern and southern Philippines. The aim of the anthology is that the student will learn to empathize with experience rendered in language, appreciate the Filipino…

Laygo, Teresito M., Comp.

328

Effects of zinc on cadmium uptake by spring wheat ( Triticum aestivum, L. ): long-time hydroponic study and short-time 109 Cd tracing study  

Microsoft Academic Search

To investigate effects of Zn on Cd uptake by spring wheat (Triticum aestivum, L.) in solution culture, long-time hydroponic experiment (1 month) (Experiment 1) and short-time Cd isotope (109Cd) tracing experiment (24 h) (Experiment 2) were conducted. In Experiment 1, spring wheat (cv. Brookton) was grown in nutrient\\u000a solution at uniform cadmium concentration of 20 ?mol\\/L and 10 zinc concentrations

Zhao Zhong-qiu; Zhu Yong-guan; Cai Yun-long

2005-01-01

329

Revisiting Teachers as Learners  

ERIC Educational Resources Information Center

This article revisits the concept of teachers as learners within the context of radical changes that have taken place within the education system in England over the past 25 years. The concept of "professional courage" is discussed and examined in relation to questions and issues raised by Paulo Freire in a series of letters to teachers (1997).…

Thomson, Liz

2008-01-01

330

Revisiting the Rhetorical Curriculum  

ERIC Educational Resources Information Center

The aim of the special strand on "Revisiting the rhetorical curriculum" is to explore the educational potential of a new rhetorical perspective, specifically in relation to different traditions within educational and rhetorical studies. This implies that we do not only look at education "in" rhetoric, but that we position education also "as" a…

Rutten, Kris; Soetaert, Ronald

2012-01-01

331

Revisiting Curriculum Potential  

ERIC Educational Resources Information Center

This article analyzes the notion of curriculum potential by revisiting the ideas of Miriam Ben-Peretz and Joseph Schwab. Invoking the German "Didaktik" tradition and by way of a curriculum-making framework, the paper argues that interpreting curriculum materials for curriculum potential requires a careful analysis and unpacking of the meanings and…

Deng, Zongyi

2011-01-01

332

Google Scholar revisited  

Microsoft Academic Search

Purpose – The purpose of this paper is to revisit Google Scholar. Design\\/methodology\\/approach – This paper discusses the strengths and weaknesses of Google Scholar. Findings – The Google Books project has given a massive and valuable boost to the already rich and diverse content of Google Scholar. The downside of the growth is that significant gaps remain for top ranking

Péter Jacsó

2008-01-01

333

Superresolution Imaging—Revisited  

Microsoft Academic Search

Methods for synthesizing and recovering signal features below the diffraction limit are revisited and interpreted as instances of a single unifying principle. Based on the review of the Rayleigh resolution limit and Abbe's theory of the microscope two distinct strategies can be distinguished: The first uses suitable encoding methods to increase the signal bandwidth passed through the imaging system at

Markus E. Testorf; Michael A. Fiddy

2010-01-01

334

A Hydrostatic Paradox Revisited  

ERIC Educational Resources Information Center

This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

Ganci, Salvatore

2012-01-01

335

Clinical ethics revisited  

PubMed Central

A decade ago, we reviewed the field of clinical ethics; assessed its progress in research, education, and ethics committees and consultation; and made predictions about the future of the field. In this article, we revisit clinical ethics to examine our earlier observations, highlight key developments, and discuss remaining challenges for clinical ethics, including the need to develop a global perspective on clinical ethics problems.

Singer, Peter A; Pellegrino, Edmund D; Siegler, Mark

2001-01-01

336

Clinical ethics revisited  

Microsoft Academic Search

A decade ago, we reviewed the field of clinical ethics; assessed its progress in research, education, and ethics committees and consultation; and made predictions about the future of the field. In this article, we revisit clinical ethics to examine our earlier observations, highlight key developments, and discuss remaining challenges for clinical ethics, including the need to develop a global perspective

Peter A Singer; Edmund D Pellegrino; Mark Siegler

2001-01-01

337

Revisiting the learning organisation  

Microsoft Academic Search

The concept of the learning organisation is now established, yet there are not many organisations that claim to be learning organisations. Revisits the concept of the learning organisation to illustrate the key attributes. Suggests some of the key requirements to make the transformation into a learning organisation and highlights the benefits that can accrue.

Simon Evans

1998-01-01

338

Short-term pollution forecasts based on linear and nonlinear methods of time series analysis  

NASA Astrophysics Data System (ADS)

Urban air pollution is a complex mixture of toxic components, which may induce acute and chronic responses from sensitive groups, such as children and people with previous heart and respiratory insufficiencies. However, air pollution, presents a highly chaotic and non-linear behavior. In this work we analyzed several pollutants time series recorded in the urban area of Lisbon (Portugal) for the 2002-2006 period. Linear and nonlinear methods were applied in order to assess NO2, PM10 and O3 main trends and fluctuations and finally, to produce daily forecasts of the referred pollutants. Here we evaluate the potential of linear and non-linear neural networks (NN) to produce short-term forecasts, and also the contribution of meteorological variables (daily mean temperature, radiation, wind speed and direction, boundary layer height, humidity) to pollutants dispersion. Additionally, we assess the role of large-scale circulation patterns, usually referred as Weather types (WT) (from the ERA40/ECMWF and ECMWF SLP database) towards the occurrence of critical pollution events identified previously. The presence and importance of trends and fluctuation is addressed by means of two modelling approaches: (1) raw data modelling; (2) residuals modelling (after the removal of the trends from the original data). The relative importance of two periodic components, the weekly and the monthly cycles, is addressed. For the three pollutants, the approach based on the removal of the weekly cycle presents the best results, comparatively to the removal of the monthly cycle or to the use of the raw data. The best predictors are chosen independently for each monitoring station and pollutant through an objective procedure (backward stepwise regression). The analysis reveals that the most significant variables in predicting NO2 concentration are several NO2 measures, wind direction and speed and global radiation, while for O3 correspond to several O3 measures, O3 precursors and WT classification. Finally, for PM10, several PM10 measures, NO2 and CO, maximum temperature, wind direction, humidity and BLH, i.e., pollutants related to road traffic emissions and meteorological variables related to atmospheric stability. Moreover, validation results showed that non-linear NN models, on average, perform as well or worse as linear models for NO2, O3 and PM10. The results attained with an independent sample reveal a very good correlation between the predicted and observed values which confirms that linear models generalize well for independent data. The applied methods permit producing, in a simple and cost efficient way, different results for each monitoring station, which allows a good spatial resolution for Lisbon's urban area. Consistent with the performance measures, high pollutants' peak values were reproduced in most cases by each model. The attained results raises good prospects for urban air quality characterization, allowing further developments in order to produce an integrated air quality surveillance system for the area of Lisbon.

Russo, A.; Trigo, R. M.

2012-04-01

339

Network Time Domain Transmission Line Representation for Short-Pulse Radiation by Periodic Phased Arrays  

Microsoft Academic Search

We are in the process of performing an efiective wide-band analysis for characterizing the electrodynamic behavior of phased array antennas, inflnite periodic structures, frequency selective surfaces and related applications, with emphasis on gaining physical insight into the phenomenology of short-pulse radiation. The present contribution shows the current status of our network-oriented dyadic TD GF for a planar array of sequentially

F. Capolino; L. B. Felsen; A. Della Villa

340

Short-term memory for time in children and adults: A behavioral study and a model  

Microsoft Academic Search

This experiment investigated the effect of the short-term retention of duration on temporal discrimination in 5- and 8-year-olds, as well as in adults, by using an episodic temporal generalization task. In each age group, the participants’ task was to compare two successive durations (a standard and a comparison duration) separated by a retention interval of 500ms, 5s, or 10s, with

Sylvie Droit-Volet; John Wearden; Maria Delgado-Yonger

2007-01-01

341

Setting the revisit interval in primary care  

Microsoft Academic Search

OBJECTIVE: Although longitudinal care constitutes the bulk of primary care, physicians receive little guidance on the fundamental question\\u000a of how to time follow-up visits. We sought to identify important predictors of the revisit interval and to describe the variability\\u000a in how physicians set these intervals when caring for patients with common medical conditions.\\u000a \\u000a \\u000a DESIGN: Cross-sectional survey of physicians performed at

Lisa M. Schwartz; Steven Woloshin; John H. Wasson; Roger A. Renfrew; H. Gilbert Welch

1999-01-01

342

Improving novelty detection in short time series through RBF-DDA parameter adjustment  

Microsoft Academic Search

Novelty detection in time series is an important problem with application in different domains. such as machine failure detection, fraud detection and auditing. We have previously proposed a method for time series novelty detection based on classification of time series windows by RBF-DDA neural networks. The paper proposes a method to be used in conjunction with this time series novelty

A. L. I. Oliveira; F. B. L. Neto; S. R. L. Meira

2004-01-01

343

Investigation of the short-time photodissociation dynamics of trans-1-bromo-2-iodoethane in the A-band absorption  

NASA Astrophysics Data System (ADS)

We have obtained resonance Raman spectra and absolute Raman cross section measurements at five excitation wavelengths within the A-band absorption for 1-bromo-2-iodoethane in cyclohexane solution. The resonance Raman spectra have most of their intensity in the fundamentals, overtones, and combination bands of six Franck-Condon active vibrational modes; the nominal CCI bend, C-I stretch, C-Br stretch, C-C stretch, CH2 wag with the Br atom attached to the CH2 group, and CH2 wag with the I atom attached to the CH2 group. The resonance Raman intensities and A-band absorption spectrum were simulated using a simple model and time-dependent wave packet calculations. The simulation results and normal mode descriptions were used to find the short-time photodissociation dynamics in terms of internal coordinate displacements. The A-band short-time photodissociation dynamics for trans-1-bromo-2-iodoethane show that the C-I, C-Br, and C-C bonds as well as the CCI, CCBr, HCC, ICH, and BrCH angles have significant changes during the initial stages of the photodissociation reaction. This indicates the photodissociation reaction has a large degree of multidimensional character and suggests that the bromoethyl photofragment receives substantial internal excitation in so far as the short-time photodissociation dynamics determines the energy partitioning. Comparison of our results for 1-bromo-2-iodoethane with the A-band short-time dynamics of iodoethane, 1-chloro-2-iodoethane, and 1,2-diiodoethane and the trends observed for their A-band absorption spectra suggest that both the C-I and C-Br bonds experience a noticeable amount of photoexcitation.

Zheng, Xuming; Phillips, David Lee

1999-01-01

344

Existence of short-time approximations of any polynomial order for the computation of density matrices by path integral methods  

NASA Astrophysics Data System (ADS)

In this paper I provide significant mathematical evidence in support of the existence of direct short-time approximations of any polynomial order for the computation of density matrices of physical systems described by arbitrarily smooth and bounded from below potentials. While for Theorem 2, which is “experimental,” I only provide a “physicist’s” proof, I believe the present development is mathematically sound. As a verification, I explicitly construct two short-time approximations to the density matrix having convergence orders 3 and 4, respectively. Furthermore, in Appendix B, I derive the convergence constant for the trapezoidal Trotter path integral technique. The convergence orders and constants are then verified by numerical simulations. While the two short-time approximations constructed are of sure interest to physicists and chemists involved in Monte Carlo path integral simulations, the present paper is also aimed at the mathematical community, who might find the results interesting and worth exploring. I conclude the paper by discussing the implications of the present findings with respect to the solvability of the dynamical sign problem appearing in real-time Feynman path integral simulations.

Predescu, Cristian

2004-05-01

345

Existence of short-time approximations of any polynomial order for the computation of density matrices by path integral methods.  

PubMed

In this paper I provide significant mathematical evidence in support of the existence of direct short-time approximations of any polynomial order for the computation of density matrices of physical systems described by arbitrarily smooth and bounded from below potentials. While for Theorem 2, which is "experimental," I only provide a "physicist's" proof, I believe the present development is mathematically sound. As a verification, I explicitly construct two short-time approximations to the density matrix having convergence orders 3 and 4, respectively. Furthermore, in Appendix B, I derive the convergence constant for the trapezoidal Trotter path integral technique. The convergence orders and constants are then verified by numerical simulations. While the two short-time approximations constructed are of sure interest to physicists and chemists involved in Monte Carlo path integral simulations, the present paper is also aimed at the mathematical community, who might find the results interesting and worth exploring. I conclude the paper by discussing the implications of the present findings with respect to the solvability of the dynamical sign problem appearing in real-time Feynman path integral simulations. PMID:15244971

Predescu, Cristian

2004-05-01

346

Time-resolved measurement of the quantum states of photons using two-photon interference with short-time reference pulses  

SciTech Connect

To fully utilize the energy-time degree of freedom of photons for optical quantum-information processes, it is necessary to control and characterize the temporal quantum states of the photons at extremely short time scales. For measurements of the temporal coherence of the quantum states beyond the time resolution of available detectors, two-photon interference with a photon in a short-time reference pulse may be a viable alternative. In this paper, we derive the temporal measurement operators for the bunching statistics of a single-photon input state with a photon from a weak coherent reference pulse. It is shown that the effects of the pulse shape of the reference pulse can be expressed in terms of a spectral filter selecting the bandwidth within which the measurement can be treated as an ideal projection on eigenstates of time. For full quantum tomography, temporal coherence can be determined by using superpositions of reference pulses at two different times. Moreover, energy-time entanglement can be evaluated based on the two-by-two entanglement observed in the coherences between pairs of detection times.

Ren Changliang; Hofmann, Holger F. [Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashi Hiroshima 739-8530 (Japan) and JST, CREST, Sanbancho 5, Chiyoda ku, Tokyo 102-0075 (Japan)

2011-09-15

347

A multi-reflection time-of-flight mass spectrometer for mass measurements of short-lived nuclei  

NASA Astrophysics Data System (ADS)

In order to determine binding energies of short-lived nuclei we have developed a time-of-flight mass spectrometer of high mass resolving power m/? m. This spectrometer achieves a very long ion flight path by repeatedly reflecting ions between two electrostatic ion mirrors. The nuclei to be investigated are produced in heavy ion fragmentations and separated in-flight by a fragment separator. These energetic ions are thermalized in a catcher gas cell injected into an RF ion-guide and then into an ion trap to be cooled, bunched and entered into the time-of-flight spectrometer. This technique should allow to determine the masses of short-lived nuclei with high efficiency. Using stable ions, the so far achieved mass resolving power m/? m exceeded 65,000.

Ishida, Y.; Wada, M.; Wollnik, H.

2005-12-01

348

Human brain detects short-time nonlinear predictability in the temporal fine structure of deterministic chaotic sounds  

NASA Astrophysics Data System (ADS)

Deterministic nonlinear dynamical processes are ubiquitous in nature. Chaotic sounds generated by such processes may appear irregular and random in waveform, but these sounds are mathematically distinguished from random stochastic sounds in that they contain deterministic short-time predictability in their temporal fine structures. We show that the human brain distinguishes deterministic chaotic sounds from spectrally matched stochastic sounds in neural processing and perception. Deterministic chaotic sounds, even without being attended to, elicited greater cerebral cortical responses than the surrogate control sounds after about 150 ms in latency after sound onset. Listeners also clearly discriminated these sounds in perception. The results support the hypothesis that the human auditory system is sensitive to the subtle short-time predictability embedded in the temporal fine structure of sounds.

Itoh, Kosuke; Nakada, Tsutomu

2013-04-01

349

Short-Term Prediction of Travel Time using Neural Networks on an Interurban Highway  

Microsoft Academic Search

The main purpose of this study was to investigate the predictability of travel time with a model based on travel time data measured in the field on an interurban highway. Another purpose was to determine whether the forecasts would be accurate enough to implement the model in an actual online travel time information service. The study was carried out on

Satu Innamaa

2005-01-01

350

Human express saccades: extremely short reaction times of goal directed eye movements  

Microsoft Academic Search

Human subjects were asked to execute a saccade from a central fixation point to a peripheral target at the time of its onset. When the fixation point is turned off some time (˜ 200 ms) before target onset, such that there is a gap where subjects see nothing, the distribution of their saccadic reaction times is bimodal with one narrow

B. Fischer; E. Ramsperger

1984-01-01

351

On a possible method for measuring the energy of neutrons in short time emission  

SciTech Connect

The author considers the possibility to estimate the energy of the neutrons coming, e.g., from piezonuclear effects (in electrolytic cells or in gas-metal system) using the counts of two detectors, assuming that the emission of neutrons follows a discharge-like behavior and therefore with a very short duration of the emission with respect to the period between two successive emissions. The authors show that using an {sup 3}He counter as a flat response detector with a constant intrinsic efficiency over a range from tens of keVs to few MeVs and a BF{sub 3} counter having in the same range an exponential intrinsic efficiency, it is possible in principle to write down an equation connecting the {sup 10}B microscopical cross section, for n {minus} {alpha} reaction, and the counts of these two detectors. The {sup 10}B microscopical cross section is related with the energy of the incident neutrons and a tabulate list of these values is available; therefore it can give a way to estimate this energy without using the spectroscopy method because of the very short duration of the emission.

Cardone, F. (INFN, Rome (Italy))

1991-01-01

352

A multi-reflection time-of-flight mass spectrometer for mass measurements of short-lived nuclei  

Microsoft Academic Search

In order to determine binding energies of short-lived nuclei we have developed a time-of-flight mass spectrometer of high mass resolving power m\\/?m. This spectrometer achieves a very long ion flight path by repeatedly reflecting ions between two electrostatic ion mirrors. The nuclei to be investigated are produced in heavy ion fragmentations and separated in-flight by a fragment separator. These energetic

Y. Ishida; M. Wada; H. Wollnik

2005-01-01

353

Short-pulse Laser Induced Transient Structure Formation and Ablation Studied with Time-resolved Coherent XUV-scattering  

NASA Astrophysics Data System (ADS)

The structural dynamics of short-pulse laser irradiated surfaces and nano-structures has been studied with nm spatial and ultrafast temporal resolution by means of single-shot coherent XUV-scattering techniques. The experiments allowed us to time-resolve the formation of laser-induced periodic surface structures, and to follow the expansion and disintegration of nano-objects during laser ablation.

Sokolowski-Tinten, Klaus; Barty, Anton; Boutet, Sebastien; Shymanovich, Uladzimir; Chapman, Henry; Bogan, Mike; Marchesini, Stefano; Hau-Riege, Stefan; Stojanovic, Nikola; Bonse, Jörn; Rosandi, Yudi; Urbassek, Herbert M.; Tobey, Ra'anan; Ehrke, Henri; Cavalleri, Andrea; Düsterer, Stefan; Redlin, Harald; Frank, Matthias; Bajt, Sasa; Schulz, Joachim; Seibert, Marvin; Hajdu, Janos; Treusch, Rolf; Bostedt, Christoph; Hoener, M.; Möller, T.

2010-10-01

354

Numerical study of the effect of normalised window size, sampling frequency, and noise level on short time Fourier transform analysis  

SciTech Connect

Photonic Doppler velocimetry, also known as heterodyne velocimetry, is a widely used optical technique that requires the analysis of frequency modulated signals. This paper describes an investigation into the errors of short time Fourier transform analysis. The number of variables requiring investigation was reduced by means of an equivalence principle. Error predictions, as the number of cycles, samples per cycle, noise level, and window type were varied, are presented. The results were found to be in good agreement with analytical models.

Ota, T. A. [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom)] [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom)

2013-10-15

355

Short-time-scale variability of near-bottom seston composition during spring in a warm temperate sea  

Microsoft Academic Search

In this study, environmental (temperature, wave height, river run-off, and currents) and biological (Chlorophyll a (Chl a), total particulate carbon (TPC), particulate organic carbon (POC), particulate organic nitrogen (PON), proteins, and carbohydrates)\\u000a features were analysed in Mediterranean coastal waters using a short-time-scale approach. In order to explain shifts in the\\u000a biomass variability within the spring (a period of intense production

Sergio Rossi; Josep-Maria Gili

2007-01-01

356

Short-time-scale variability in ventilation and export productivity during the formation of Mediterranean sapropel S1  

Microsoft Academic Search

High-resolution laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) scanning of laminated sediments from the Urania basin is used to investigate short-time-scale variability in export productivity and redox conditions during the formation of eastern Mediterranean sapropel S1. Sedimentary enrichments of molybdenum (Mo), vanadium (V), and uranium (U) reflect deep-water redox conditions, most likely those near to the seawater-brine interface, while enrichment of

Tom Jilbert; Gert-Jan Reichart; Paul Mason; Gert J. de Lange

2010-01-01

357

On experimental evidence of chaotic dynamics over short time scales in solar wind and cometary data using nonlinear prediction techniques  

Microsoft Academic Search

Strong indications of chaotic dynamics underlying in the interplanetary and cometary magnetic field fluctuations over short time scales are identified using HEOS-2 spacecraft (at 1 AU), Pioneer 10 (at 4.8 AU), Pioneer 11 (at 20 AU) and ICE (Giacobini-Zinner cometary environment) high-resolution measurements. Other non-chaotic candidate processes, such as linear deterministic models, fractal Brownian motion, and linear gaussian stochastic models

J. M. Polygiannakis; X. Moussas

1994-01-01

358

Numerical study of the effect of normalised window size, sampling frequency, and noise level on short time Fourier transform analysis.  

PubMed

Photonic Doppler velocimetry, also known as heterodyne velocimetry, is a widely used optical technique that requires the analysis of frequency modulated signals. This paper describes an investigation into the errors of short time Fourier transform analysis. The number of variables requiring investigation was reduced by means of an equivalence principle. Error predictions, as the number of cycles, samples per cycle, noise level, and window type were varied, are presented. The results were found to be in good agreement with analytical models. PMID:24182128

Ota, T A

2013-10-01

359

Structure and short-time dynamics in suspensions of charged silica spheres in the entire fluid regime  

NASA Astrophysics Data System (ADS)

We present an experimental study of short-time diffusion properties in fluidlike suspensions of monodisperse charge-stabilized silica spheres suspended in dimethylformamide. The static structure factor S(q), the short-time diffusion function D(q), and the hydrodynamic function H(q) have been probed by combining x-ray photon correlation spectroscopy experiments with static small-angle x-ray scattering. Our experiments cover the full liquid-state part of the phase diagram, including de-ionized systems right at the liquid-solid phase boundary. We show that the dynamic data can be consistently described by the renormalized density fluctuation expansion theory of Beenakker and Mazur over a wide range of concentrations and ionic strengths. In accordance with this theory and Stokesian dynamics computer simulations, the measured short-time properties cross over monotonically, with increasing salt content, from the bounding values of salt-free suspensions to those of neutral hard spheres. Moreover, we discuss an upper bound for the hydrodynamic function peak height of fluid systems based on the Hansen-Verlet freezing criterion.

Gapinski, J.; Patkowski, A.; Banchio, A. J.; Buitenhuis, J.; Holmqvist, P.; Lettinga, M. P.; Meier, G.; Nägele, G.

2009-02-01

360

Structure and short-time dynamics in suspensions of charged silica spheres in the entire fluid regime.  

PubMed

We present an experimental study of short-time diffusion properties in fluidlike suspensions of monodisperse charge-stabilized silica spheres suspended in dimethylformamide. The static structure factor S(q), the short-time diffusion function D(q), and the hydrodynamic function H(q) have been probed by combining x-ray photon correlation spectroscopy experiments with static small-angle x-ray scattering. Our experiments cover the full liquid-state part of the phase diagram, including de-ionized systems right at the liquid-solid phase boundary. We show that the dynamic data can be consistently described by the renormalized density fluctuation expansion theory of Beenakker and Mazur over a wide range of concentrations and ionic strengths. In accordance with this theory and Stokesian dynamics computer simulations, the measured short-time properties cross over monotonically, with increasing salt content, from the bounding values of salt-free suspensions to those of neutral hard spheres. Moreover, we discuss an upper bound for the hydrodynamic function peak height of fluid systems based on the Hansen-Verlet freezing criterion. PMID:19256611

Gapinski, J; Patkowski, A; Banchio, A J; Buitenhuis, J; Holmqvist, P; Lettinga, M P; Meier, G; Nägele, G

2009-02-28

361

Impact of short-time urine freezing on the sensitivity of an established schistosoma real-time PCR assay.  

PubMed

Urogenital schistosomiaisis is a serious public health problem in sub-Saharan Africa. In this study, we have updated an established real-time polymerase chain reaction (PCR) routinely used in our laboratory. Schistosoma genus-specific real-time PCR was performed on DNA isolated from 85 urine samples and pellets obtained after centrifugation without and after frozen storage. The results revealed that concentration by centrifugation of the urine samples and freezing of the samples before extracting DNA improves the sensitivity of the PCR. PMID:24710612

Kenguele, Hilaire M; Adegnika, Ayola A; Nkoma, Anne-Marie; Ateba-Ngoa, Ulysse; Mbong, Mirabeau; Zinsou, Jeannot; Lell, Bertrand; Verweij, Jaco J

2014-06-01

362

Multiscale approach combining nonadiabatic dynamics with long-time radiative and non-radiative decay: Dissociative ionization of heavy rare-gas tetramers revisited  

NASA Astrophysics Data System (ADS)

A multiscale approach is proposed to address short-time nonadiabatic dynamics and long-time decay. We show the role of both radiative and non-radiative processes in cluster decay mechanisms on examples of rare-gas cluster fragmentation after electron impact ionization. Nonadiabatic molecular dynamics is used as an efficient tool for theoretical study on femto- and picosecond scales and a multiscale approach based on kinetic rates of radiative as well as non-radiative transitions, both considered as parallel reaction channels, is used for the analysis of the long-time system relaxation spanning times over microseconds to infinity. While the radiative processes are typically slow, the system relaxation through non-radiative electronic transitions connected with electron-nuclear interchange of energy may, on the other hand, significantly vary in kinetic rates according to kinetic couplings between relevant adiabatic states. While the predictions of picosecond molecular dynamics themselves fail, the results of the multiscale model for the electron-impact post-ionization fragmentation of krypton and xenon tetramers are in agreement with experiment, namely, in leading to the conclusion that charged monomers prevail. More specifically, on microsecond and longer scales, mainly slow radiative processes are substantial for krypton cluster decay, while for xenon the radiative and slow non-radiative processes compete. In general, the role of slow decay processes through non-radiative transitions is comparable with the role of radiative decay mechanism. The novel multiscale model substantially improves theoretical predictions for the xenon tetramer decay and also further improves the good agreement between theory and experiment we reached previously for krypton.

Jane?ek, Ivan; Jan?a, Tomáš; Naar, Pavel; Kalus, René; Gadea, Florent Xavier

2013-01-01

363

A mode coupling theory description of the short- and long-time dynamics of nematogens in the isotropic phase  

NASA Astrophysics Data System (ADS)

Optical heterodyne-detected optical Kerr effect (OHD-OKE) experimental data are pre-sented on nematogens 4-(trans-4'-n-octylcyclohexyl)isothiocyanatobenzene (8-CHBT), and 4-(4'-pentyl-cyclohexyl)-benzonitrile (5-PCH) in the isotropic phase. The 8-CHBT and 5-PCH data and previously published data on 4'-pentyl-4-biphenylcarbonitrile (5-CB) are analyzed using a modification of a schematic mode coupling theory (MCT) that has been successful in describing the dynamics of supercooled liquids. At long time, the OHD-OKE data (orientational relaxation) are well described with the standard Landau-de Gennes (LdG) theory. The data decay as a single exponential. The decay time diverges as the isotropic to nematic phase transition is approached from above. Previously there has been no theory that can describe the complex dynamics that occur at times short compared to the LdG exponential decay. Earlier, it has been noted that the short-time nematogen dynamics, which consist of several power laws, have a functional form identical to that observed for the short time behavior of the orientational relaxation of supercooled liquids. The temperature-dependent orientational dynamics of supercooled liquids have recently been successfully described using a schematic mode coupling theory. The schematic MCT theory that fits the supercooled liquid data does not reproduce the nematogen data within experimental error. The similarities of the nematogen data to the supercooled liquid data are the motivation for applying a modification of the successful MCT theory to nematogen dynamics in the isotropic phase. The results presented below show that the new schematic MCT theory does an excellent job of reproducing the nematogen isotropic phase OHD-OKE data on all time scales and at all temperatures.

Li, Jie; Cang, Hu; Andersen, Hans C.; Fayer, M. D.

2006-01-01

364

Short-time OD matrix estimation for a complex junction using Fuzzy-Timed High-Level Petri Nets  

Microsoft Academic Search

The OD matrix at a signalised junction estimated for traffic light cycle represents a crucial information for trans- portation systems. A new dynamic two-steps method is proposed to estimate such an OD matrix. First, a vehicle conservation law is build in a dynamical way for each traffic light cycle using Fuz zy- Timed High-Level Petri Nets (FTHN). It is represented

Krystyna Biletska; Marie-Helene Masson; Sophie Midenet

2010-01-01

365

Horizontal Structure of 500 mb Height Fluctuations with Long, Intermediate and Short Time Scales  

Microsoft Academic Search

Maps of standard deviations and one-point correlation maps based on twice-daily data subjected to a variety of temporal filters are presented, in order to document the horizontal structure of 500 mb height fluctuations with different time scales. The filters have been chosen to isolate fluctuations with long time scales (periods much longer than 30 days), intermediate time scales (10-30 day

Maurice L. Blackmon; Y.-H. Lee; John M. Wallace

1984-01-01

366

Vessel failure time for a low-pressure short-term station blackout in a BWR-4  

SciTech Connect

A low-pressure, short-term station blackout severe accident sequence has been analyzed using the MELCOR code, version 1.8.1, in a boiling water reactor (BWR)-4. This paper presents a sensitivity study evaluating the effect of several MELCOR input parameters on vessel failure time. Results using the MELCOR/CORBH package and the BWRSAR code are also presented and compared to the MELCOR results. These calculated vessel failure times are discussed, and a judgment is offered as to which is the most realistic.

Carbajo, J.J. (Martin Marietta Energy System, Oak Ridge, TN (United States))

1993-01-01

367

Short time-scale X-ray variability in the AM Her-type binary EF Eridani  

Microsoft Academic Search

ROSAT Position-Sensitive Proportional Counter (PSPC) observations of the AM Her-type binary EF Eri are presented. In the PSPC spectrum the hard-X-ray bremsstrahlung component and the soft-X-ray quasi-blackbody component are clearly separated. Study of the short-time-scale variability of both components shows the almost complete absence of quasi-periodic oscillations in the few-minute range, large-amplitude aperiodic soft-X-ray flaring, and zero correlation at zero-time-lag

K. Beuermann; H.-C. Thomas; W. Pietsch

1991-01-01

368

Comparison of Short-Term and Time-Independent Earthquake Forecast Models for Southern California  

Microsoft Academic Search

We have initially developed a time-independent forecast for southern California by smoothing the locations of magnitude 2 and larger earthquakes. We show that using small m 2 earthquakes gives a reasonably good prediction of m 5 earthquakes. Our forecast outperforms other time-independent models (Kagan and Jackson, 1994; Frankel et al., 1997), mostly because it has higher spatial resolution. We have

Agnes Helmstetter; Yan Y. Kagan; David D. Jackson

2006-01-01

369

Test of the exponential decay law at short decay times using tau leptons  

Microsoft Academic Search

Quantum mechanics predicts an exponential distribution for the decay time of massive particles. However, deviations are expected for decay times shorter than about 10?13 s in models conjecturing the existence of hidden variables. Following a recent proposal, the decay length distribution of 5843 ? leptons decaying into 3 charged particles was analyzed in search of such a deviation. The deviation

Gideon Alexander; J. Allison; N. Altekamp; K A Ametewee; K. J. Anderson; S. Anderson; S. Arcelli; D A Axen; Georges Azuelos; A. H. Ball; E. Barberio; R. J. Barlow; R. Bartoldus; J Richard Batley; G. Beaudoin; J. Bechtluft; G. A. Beck; C. Beeston; T. Behnke; A. N. Bell; K. W. Bell; G. Bella; Stanislaus Cornelius Maria Bentvelsen; P. Berlich; Siegfried Bethke; O. Biebel; Ian J Bloodworth; J. E. Bloomer; P. Bock; H. M. Bosch; M. Boutemeur; B. T. Bouwens; S. Braibant; P G Bright-Thomas; R. M. Brown; Helfried J Burckhart; C. Burgard; R. Bürgin; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Chang Y; C. Charlesworth; D. G. Charlton; D. Chrisman; S. L. Chu; P. E. L. Clarke; S. G. Clowes; I. Cohen; J. E. Conboy; O. C. Cooke; M. Cuffiani; S. Dado; C. Dallapiccola; G. M. Dallavalle; C L Darling; S. De Jong; L. A. del Pozo; M. S. Dixit; E. do Couto e Silva; E. Duchovni; G. Duckeck; I. P. Duerdoth; U. C. Dunwoody; J. E. G. Edwards; P. G. Estabrooks; H. G. Evans; Franco Luigi Fabbri; B. Fabbro; P. Fath; F. Fiedler; M. Fierro; Margret Fincke-Keeler; H. M. Fischer; R. Folman; D. G. Fong; M. Foucher; H. Fukui; A. Fürtjes; P. Gagnon; A. Gaidot; J. W. Gary; J. Gascon; S. M. Gascon-Shotkin; N. I. Geddes; C. Geich-Gimbel; S. W. Gensler; F. X. Gentit; T. Geralis; G. Giacomelli; P. Giacomelli; R. Giacomelli; V. Gibson; W. R. Gibson; D. M. Gingrich; J. Goldberg; M. J. Goodrick; W. Gorn; C. Grandi; E. Gross; C. Hajdu; G. G. Hanson; M. Hansroul; M. Hapke; C. K. Hargrove; P. A. Hart; C. Hartmann; M. Hauschild; C. M. Hawkes; R. Hawkings; Richard J Hemingway; G. Herten; R. D. Heuer; M. D. Hildreth; J. C. Hill; S. J. Hillier; T. Hilse; P. R. Hobson; D. Hochman; R James Homer; A. K. Honma; D. Horváth; R. Howard; R. E. Hughes-Jones; D. E. Hutchcroft; P. Igo-Kemenes; D. C. Imrie; A. Jawahery; P. W. Jeffreys; H. Jeremie; Martin Paul Jimack; A. Joly; M. Jones; R. W. L. Jones; U. Jost; P. Jovanovic; D A Karlen; T. Kawamoto; Richard K Keeler; R. G. Kellogg; B. W. Kennedy; B. J. King; J. King; J. Kirk; S. Kluth; T. Kobayashi; M. Kobel; D. S. Koetke; T. P. Kokott; S. Komamiya; R V Kowalewski; T. Kress; P. Krieger; J. von Krogh; P. Kyberd; G. D. Lafferty; H. Lafoux; R. Lahmann; W. P. Lai; D. Lanske; J. Lauber; J. G. Layter; A. M. Lee; E. Lefebvre; Daniel Lellouch; J. Letts; L. Levinson; C. Lewis; S. L. Lloyd; F. K. Loebinger; G. D. Long; B. Lorazo; Michael J Losty; J. Ludwig; A. Luig; A. Malik; M. Mannelli; S. Marcellini; C. Markus; A. J. Martin; J. P. Martin; G. Martinez; T. Mashimo; W. Matthews; P. Mättig; W. J. McDonald; J A McKenna; E. A. Mckigney; T. J. McMahon; A. I. McNab; F. Meijers; S. Menke; F. S. Merritt; H. Mes; J. Meyer; Aldo Michelini; G. Mikenberg; D. J. Miller; R. Mir; W. Mohr; A. Montanari; T. Mori; M. Morii; U. Müller; B. Nellen; B. Nijjhar; R. Nisius; S. W. O'Neale; F. G. Oakham; F. Odorici; H. O. Ogren; N. J. Oldershaw; T. Omori; C. J. Oram; M. J. Oreglia; S. Orito; M. Palazzo; J. Pálinkás; F. M. Palmonari; J. P. Pansart; G. Pásztor; J. R. Pater; G. N. Patrick; M. J. Pearce; P. D. Phillips; J. E. Pilcher; J L Pinfold; D. E. Plane; P R Poffenberger; B. Poli; A. Posthaus; T. W. Pritchard; H. Przysiezniak; D. L. Rees; D. Rigby; M. G. Rison; S. A. Robins; N L Rodning; J. M. Roney; E. Ros; A. M. Rossi; M. Rosvick; P. Routenburg; Y. Rozen; K. Runge; O. Runolfsson; D. R. Rust; R. Rylko; E Sarkisyan-Grinbaum; M. Sasaki; C. Sbarra; A. D. Schaile; O. Schaile; F. Scharf; P. Scharff-Hansen; P. Schenk; B. Schmitt; M. Schröder; H. C. Schultz-Coulon; M. Schulz; P. Schütz; J. Schwiening; W. G. Scott; T. G. Shears; B. C. Shen; C. H. Shepherd-Themistocleous; P. Sherwood; G. P. Siroli; A. Sittler; A. Skillman; A. Skuja; A. M. Smith; T. J. Smith; G. A. Snow; Randall J Sobie; S. Söldner-Rembold; R. W. Springer; M. Sproston; A. Stahl; M. Starks; C. Stegmann; K. Stephens; J. Steuerer; B. Stockhausen; D. Strom; F. Strumia; P. Szymanski; R. Tafirout; H. Takeda; P. Taras; S. Tarem; M. Tecchio; N. Tesch; M. A. Thomson; E. von Törne; S. Towers; M. Tscheulin; T. Tsukamoto; E. Tsur; A. S. Turcot; M. F. Turner-Watson; P. Utzat; R. Van Kooten; G. Vasseur; P. Vikas; M G Vincter; E. H. Vokurka; F. Wäckerle; A. Wagner; D. L. Wagner; C. P. Ward; D. R. Ward; J. J. Ward; P. M. Watkins; A. T. Watson; N. K. Watson; P. Weber; P. S. Wells; N. Wermes; B. Wilkens; G. W. Wilson; J. A. Wilson; T. Wlodek; G. Wolf; S A Wotton; T. R. Wyatt; S M Xella; S. Yamashita; G. Yekutieli; V. Zacek

1996-01-01

370

Support Vector Machine Technique for the Short Term Prediction of Travel Time  

Microsoft Academic Search

A vast majority of urban transportation systems in North America are equipped with traffic surveillance systems that provide real time traffic information to traffic management centers. The information from these are processed and provided back to the travelers in real time. However, the travelers are interested to know not only the current traffic information, but also the future traffic conditions

Lelitha Vanajakshi; Laurence R. Rilett

2007-01-01

371

Short-term prediction of motorway travel time using ANPR and loop data  

Microsoft Academic Search

Travel time is a good operational measure of the effectiveness of transportation systems. The ability to accurately predict motorway and arterial travel times is a critical component for many intelligent transportation systems (ITS) applications. Advanced traffic data collection systems using inductive loop detectors and video cameras have been installed, particularly for motorway networks. An inductive loop can provide traffic flow

Yanying Li

2008-01-01

372

Short-Term Arterial Travel Time Prediction for Advanced Traveler Information Systems  

Microsoft Academic Search

While vehicular flows on freeways are often treated as uninterrupted flows, flows on arterials are conceivably much more complicated because vehicles traveling on arterials are not only subject to queuing delay but also to signal delay. Prediction of travel time is potentially more challenging for arterials than for freeways. This article proposes a simple model for arterial travel time prediction.

WEI-HUA LIN; AMIT KULKARNI; PITU MIRCHANDANI

2004-01-01

373

Time does not cause forgetting in short-term serial recall.  

PubMed

Time-based theories expect memory performance to decline as the delay between study and recall of an item increases. The assumption of time-based forgetting, central to many models of serial recall, underpins their key behaviors. Here we compare the predictions of time-based and event-based models by simulation and test them in two experiments using a novel manipulation of the delay between study and retrieval. Participants were trained, via corrective feedback, to recall at different speeds, thus varying total recall time from 6 to 10 sec. In the first experiment, participants used the keyboard to enter their responses but had to repeat a word (called the suppressor) aloud during recall to prevent rehearsal. In the second experiment, articulation was again required, but recall was verbal and was paced by the number of repetitions of the suppressor in between retrieval of items. In both experiments, serial position curves for all retrieval speeds overlapped, and output time had little or no effect. Comparative evaluation of a time-based and an event-based model confirmed that these results present a particular challenge to time-based approaches. We conclude that output interference, rather than output time, is critical in serial recall. PMID:15732687

Lewandowsky, Stephan; Duncan, Matthew; Brown, Gordon D A

2004-10-01

374

Short-time OD matrix estimation for a complex junction using fuzzy-timed high-level petri nets  

Microsoft Academic Search

The OD matrix at a signalised junction estimated for traffic light cycle represents a crucial information for transportation systems. A new dynamic two-steps method is proposed to estimate such an OD matrix. First, a vehicle conservation law is build in a dynamical way for each traffic light cycle using fuzzy-timed high-level Petri nets (FTHN). It is represented by an under-determinate

Krystyna Biletska; M.-H. Masson; S. Midenet; T. Denaeux

2009-01-01

375

Microlensing variability in FBQ 0951+2635: short-time-scale events or a long-time-scale fluctuation?  

Microsoft Academic Search

We present and analyse new R-band frames of the gravitationally lensed double quasar FBQ 0951+2635. These images were obtained with the 1.5-m AZT-22 Telescope at Maidanak (Uzbekistan) during the 2001-2006 period. Previous results in the R band (1999-2001 period) and the new data allow us to discuss the dominant kind of microlensing variability in FBQ 0951+2635. The time evolution of

V. N. Shalyapin; L. J. Goicoechea; E. Koptelova; B. P. Artamonov; A. V. Sergeyev; A. P. Zheleznyak; T. A. Akhunov; O. A. Burkhonov; S. N. Nuritdinov; A. Ullán

2009-01-01

376

Short communication: Decrease in rumination time as an indicator of the onset of calving.  

PubMed

The aim of this study was to investigate whether rumination time (RT) is affected by the onset of calving. The relationship between both feeding time and dry matter intake (DMI) to the onset of calving was also examined. In addition, the correlation between feeding behavior characteristics, described here as RT, feeding time, and DMI, was evaluated. Under test conditions, the feeding behavior of pregnant Holstein cows was recorded from the time when they were moved into calving pens (usually 7 to 5d prepartum) until the onset of calving. Feeding time and DMI were recorded by automatic feed bins; RT was measured continuously by a measuring halter based on electromyography (DairyCheck; BITSz Engineering GmbH, Zwickau, Germany), which constitutes a new approach regarding feeding behavior detection. Data analysis related to the final 72h, before the onset of calving, which were divided into twelve 6-h blocks. The last 6h (one 6-h block) before calving were compared with the 72- to 7-h time frame (11 times 6-h blocks) before calving, which was defined as the reference period. For this time period, feeding behavior data for 17 cows was fully available, which was the precondition for data analysis. In the final 6h before imminent birth, RT was significantly reduced. During this time, it was found that the mean minimum RT was 69.9±28.5min/6h compared with the mean RT of 95.5±30.8min/6h in the reference period. The average decrease in RT was 27% (25.6min/6h). In addition, feeding time and DMI were significantly reduced. The average decrease in feeding time was 57% (20.8min/6h), and in DMI it was 56% (1.9kg/6h). High correlation coefficients between feeding behavior characteristics were only found between feeding time and DMI. Values of feeding behavior among cows were characterized by high variability. Recording RT can serve as a use ful tool for predicting the timing of birth for dairy cows, but further research is necessary. PMID:24612813

Büchel, S; Sundrum, A

2014-05-01

377

Short-term sandbar variability based on video imagery: Comparison between Time-Average and Time-Variance techniques  

USGS Publications Warehouse

Time-exposure intensity (averaged) images are commonly used to locate the nearshore sandbar position (xb), based on the cross-shore locations of maximum pixel intensity (xi) of the bright bands in the images. It is not known, however, how the breaking patterns seen in Variance images (i.e. those created through standard deviation of pixel intensity over time) are related to the sandbar locations. We investigated the suitability of both Time-exposure and Variance images for sandbar detection within a multiple bar system on the southern coast of Brazil, and verified the relation between wave breaking patterns, observed as bands of high intensity in these images and cross-shore profiles of modeled wave energy dissipation (xD). Not only is Time-exposure maximum pixel intensity location (xi-Ti) well related to xb, but also to the maximum pixel intensity location of Variance images (xi-Va), although the latter was typically located 15m offshore of the former. In addition, xi-Va was observed to be better associated with xD even though xi-Ti is commonly assumed as maximum wave energy dissipation. Significant wave height (Hs) and water level (??) were observed to affect the two types of images in a similar way, with an increase in both Hs and ?? resulting in xi shifting offshore. This ??-induced xi variability has an opposite behavior to what is described in the literature, and is likely an indirect effect of higher waves breaking farther offshore during periods of storm surges. Multiple regression models performed on xi, Hs and ?? allowed the reduction of the residual errors between xb and xi, yielding accurate estimates with most residuals less than 10m. Additionally, it was found that the sandbar position was best estimated using xi-Ti (xi-Va) when xb was located shoreward (seaward) of its mean position, for both the first and the second bar. Although it is unknown whether this is an indirect hydrodynamic effect or is indeed related to the morphology, we found that this behavior can be explored to optimize sandbar estimation using video imagery, even in the absence of hydrodynamic data. ?? 2011 Elsevier B.V..

Guedes, R. M. C.; Calliari, L. J.; Holland, K. T.; Plant, N. G.; Pereira, P. S.; Alves, F. N. A.

2011-01-01

378

Sharp short and long time L? bounds for solutions to porous media equations with homogeneous Neumann boundary conditions  

NASA Astrophysics Data System (ADS)

We study a class of nonlinear diffusion equations whose model is the classical porous media equation on domains ??RN, N?3, with homogeneous Neumann boundary conditions. We improve the known results in such model case, proving sharp L-L? regularizing properties of the evolution for short time and sharp long time L? bounds for convergence of solutions to their mean value. The generality of the discussion allows to consider, almost at the same time, weighted versions of the above equation provided an appropriate weighted Sobolev inequality holds. In fact, we show that the validity of such weighted Sobolev inequality is equivalent to the validity of a suitable L-L? bound for solutions to the associated weighted porous media equation. The long time asymptotic analysis relies on the assumed weighted Sobolev inequality only, and allows to prove uniform convergence to the mean value, with the rate predicted by linearization, in such generality.

Grillo, Gabriele; Muratori, Matteo

379

Cryopreservation of epididymal sperm from ibexes (Capra pyrenaica) using short equilibration time with glycerol.  

PubMed

Two experiments were conducted to study the effect of shortening the equilibration time with the cryoprotectant glycerol before freezing epididymal sperm recovered postmortem from Iberian ibex. In the first experiment, the standard equilibration time of 3 hours was compared with 2 hours, and subjective sperm motility and quality of movement were greater (P < 0.05) in the latter group. In the second experiment, reducing the equilibration time from 2 hours to 15 minutes did not affect sperm motility (evaluated subjectively and objectively), viability, acrosomal integrity, or membrane functional integrity. In conclusion, shortening the equilibration time can be used as a technique to simplify the cryopreservation process and this provides practical advantages under field conditions. PMID:24938799

Pradiee, J; Esteso, M C; Castaño, C; Toledano-Díaz, A; López-Sebastián, A; Santiago-Moreno, J

2014-08-01

380

Parameterization of short-range time-irreversibility in nuclear forces  

Microsoft Academic Search

In a time-irreversible one-bosom-exchange nucleon-nucleon potential model Bryan and Gersten, T-violation occurs mostly in the lowest-permitted angular momentum states. This leads to the construction of a phase-shift parameterization of the 50 to 450 Mev NN data where T-violation takes place only in the lowest possible angular momentum states. Unique predictions for the relative angular distributions of time-reversalasymmetric observables P -

J. Binstock; R. Bryan; A. Gersten

1976-01-01

381

Precise Point Positioning technique for short and long baselines time transfer  

NASA Astrophysics Data System (ADS)

In this work the clock parameters determination of several timing receivers TTS-4 (AOS), ASHTECH Z-XII3T (OP, ORB, PTB, USNO) and SEPTENTRIO POLARX4TR (ORB, since February 11, 2012) by use of the Precise Point Positioning (PPP) technique were presented. The clock parameters were determined for several time links based on the data delivered by time and frequency laboratories mentioned above. The computations cover the period from January 1 to December 31, 2012 and were performed in two modes with 7-day and one-month solution for all links. All RINEX data files which include phase and code GPS data were recorded in 30-second intervals. All calculations were performed by means of Natural Resource Canada's GPS Precise Point Positioning (GPS-PPP) software based on high-quality precise satellite coordinates and satellite clock delivered by IGS as the final products. The used independent PPP technique is a very powerful and simple method which allows for better control of antenna positions in AOS and a verification of other time transfer techniques like GPS CV, GLONASS CV and TWSTFT. The PPP technique is also a very good alternative for calibration of a glass fiber link PL-AOS realized at present by AOS. Currently PPP technique is one of the main time transfer methods used at AOS what considerably improve and strengthen the quality of the Polish time scales UTC(AOS), UTC(PL), and TA(PL). KEY-WORDS: Precise Point Positioning, time transfer, IGS products, GNSS, time scales.

Lejba, Pawel; Nawrocki, Jerzy; Lemanski, Dariusz; Foks-Ryznar, Anna; Nogas, Pawel; Dunst, Piotr

2013-04-01

382

Short-Time Scale Variability of MWC349 in Optical and Radio Domains  

Microsoft Academic Search

Our multi-year monitoring of MWC349 in optical domain (VRI) and in mm radio domain (hydrogen recombination lines and continuum) revealed long-term variability with the time scales from months to years, amplitudes of a few tens of a magnitude in optical and a factor of 2 in radio, and some vague signs of possible periodicity. Looking for potential shorter-time scale variability,

Gary E. Walker; E. Sperling; V. Strelnitski

2009-01-01

383

Short-time-scale correlations between line and continuum fluxes in Cygnus X-1  

Microsoft Academic Search

We present the results of 16-s time-scale spectral fits for Cygnus X-1 in the soft state and in the transition state, using a Comptonized blackbody plus an iron line. On these time-scales, we find that that the continuum source flux can vary by factors 2-3 and that the iron-line intensity appears to track these changes well, i.e. the inferred equivalent

Thomas J. Maccarone; Paolo S. Coppi

2002-01-01

384

Short time-scale variability in the Faint Sky Variability Survey  

Microsoft Academic Search

We present the V-band variability analysis of the point sources in the Faint Sky Variability Survey on time-scales from 24 min to tens of days. We find that about one per cent of the point sources down to V = 24 are variables. We discuss the variability-detection probabilities for each field depending on field sampling, amplitude and time-scale of the

L. Morales-Rueda; P. J. Groot; T. Augusteijn; G. Nelemans; P. M. Vreeswijk; E. J. M. van den Besselaar

2006-01-01

385

Short time sports exercise boosts motor imagery patterns: implications of mental practice in rehabilitation programs  

PubMed Central

Motor imagery (MI) is a commonly used paradigm for the study of motor learning or cognitive aspects of action control. The rationale for using MI training to promote the relearning of motor function arises from research on the functional correlates that MI shares with the execution of physical movements. While most of the previous studies investigating MI were based on simple movements in the present study a more attractive mental practice was used to investigate cortical activation during MI. We measured cerebral responses with functional magnetic resonance imaging (fMRI) in twenty three healthy volunteers as they imagined playing soccer or tennis before and after a short physical sports exercise. Our results demonstrated that only 10 min of training are enough to boost MI patterns in motor related brain regions including premotor cortex and supplementary motor area (SMA) but also fronto-parietal and subcortical structures. This supports previous findings that MI has beneficial effects especially in combination with motor execution when used in motor rehabilitation or motor learning processes. We conclude that sports MI combined with an interactive game environment could be a promising additional tool in future rehabilitation programs aiming to improve upper or lower limb functions or support neuroplasticity.

Wriessnegger, Selina C.; Steyrl, David; Koschutnig, Karl; Muller-Putz, Gernot R.

2014-01-01

386

Parvalbumin tunes spike-timing and efferent short-term plasticity in striatal fast spiking interneurons.  

PubMed

? Striatal fast spiking interneurons (FSIs) modulate output of the striatum by synchronizing medium-sized spiny neurons (MSNs). Recent studies have broadened our understanding of FSIs, showing that they are implicated in severe motor disorders such as parkinsonism, dystonia and Tourette syndrome. FSIs are the only striatal neurons to express the calcium-binding protein parvalbumin (PV). This selective expression of PV raises questions about the functional role of this Ca(2+) buffer in controlling FSI Ca(2+) dynamics and, consequently, FSI spiking mode and neurotransmission. To study the functional involvement of FSIs in striatal microcircuit activity and the role of PV in FSI function, we performed perforated patch recordings on enhanced green fluorescent protein-expressing FSIs in brain slices from control and PV-/- mice. Our results revealed that PV-/- FSIs fired more regularly and were more excitable than control FSIs by a mechanism in which Ca(2+) buffering is linked to spiking activity as a result of the activation of small conductance Ca(2+)-dependent K(+) channels. A modelling approach of striatal FSIs supports our experimental results. Furthermore, PV deletion modified frequency-specific short-term plasticity at inhibitory FSI to MSN synapses. Our results therefore reinforce the hypothesis that in FSIs, PV is crucial for fine-tuning of the temporal responses of the FSI network and for the orchestration of MSN populations. This, in turn, may play a direct role in the generation and pathology-related worsening of motor rhythms. PMID:23551945

Orduz, David; Bischop, Don Patrick; Schwaller, Beat; Schiffmann, Serge N; Gall, David

2013-07-01

387

Short Planning Turn-Around Time and High Flexibility of the Swedish Astronomy/Aeronomy Satellite Odin  

NASA Astrophysics Data System (ADS)

The Swedish small satellite Odin combines two different scientific disciplines, astronomy and atmospheric research. It has a 3-axis stabilized, zero momentum, attitude control system that operates in two different modes, an inertial pointing astronomy mode and an atmospheric mode providing pointing/scanning of the Earth limb. The reference attitude for the atmospheric mode is created by a versatile reference attitude generator, providing also capability for observing and tracking any celestial or solar system objects. The absolute pointing requirements in the scientific modes are 15 arc-seconds inertial pointing and 1.2 arc-minutes in atmospheric mode reconstructed attitude. One part of the Odin mission is to observe the formation of the ozone holes at the poles in spring and fall and another is to observe moving celestial objects such as comets. The unpredictability of when such observation opportunities occur together with rapidly changing scientific demands put high requirements on a short turn- around time for the Operations Cycle - science demand, planning and command generation, reconstruction of attitude history, feedback and delivery to scientists. A small efficient team, including also members that was deeply involved with and responsible for the design and development of the system, has been a key to provide this a short turn-around time for the Operations Cycle. It is possible to safely reconfigure the satellite for either of two disciplines with short notice and have a reconstructed attitude available to the users shortly after the observations have been done. The small efficient team together with modular software based on MATLAB also facilitates in rapidly meeting new demands on the planning and attitude reconstruction from the users.

Jakobsson, B.; Karlsson, T.; Nylund, M.; Olsson, T.; Vinterhav, E.

2002-01-01

388

Time-resolved plasma spectroscopy of thin foils heated by a relativistic-intensity short-pulse laser  

NASA Astrophysics Data System (ADS)

Time-resolved K-shell x-ray spectra are recorded from sub-100 nm aluminum foils irradiated by 150-fs laser pulses at relativistic intensities of I?2=2×1018 W ?m2/cm2. The thermal penetration depth is greater than the foil thickness in these targets so that uniform heating takes place at constant density before hydrodynamic motion occurs. The high-contrast, high-intensity laser pulse, broad spectral band, and short time resolution utilized in this experiment permit a simplified interpretation of the dynamical evolution of the radiating matter. The observed spectrum displays two distinct phases. At early time, ?500 fs after detecting target emission, a broad quasicontinuous spectral feature with strong satellite emission from multiply excited levels is seen. At a later time, the He-like resonance line emission is dominant. The time-integrated data is in accord with previous studies with time resolution greater than 1 ps. The early time satellite emission is shown to be a signature of an initial large area, high density, low-temperature plasma created in the foil by fast electrons accelerated by the intense radiation field in the laser spot. We conclude that, because of this early time phenomenon and contrary to previous predictions, a short, high-intensity laser pulse incident on a thin foil does not create a uniform hot and dense plasma. The heating mechanism has been studied as a function of foil thickness, laser pulse length, and intensity. In addition, the spectra are found to be in broad agreement with a hydrodynamic expansion code postprocessed by a collisional-radiative model based on superconfiguration average rates and on the unresolved transition array formalism.

Audebert, P.; Shepherd, R.; Fournier, K. B.; Peyrusse, O.; Price, D.; Lee, R. W.; Springer, P.; Gauthier, J.-C.; Klein, L.

2002-12-01

389

Time-resolved plasma spectroscopy of thin foils heated by a relativistic-intensity short-pulse laser.  

PubMed

Time-resolved K-shell x-ray spectra are recorded from sub-100 nm aluminum foils irradiated by 150-fs laser pulses at relativistic intensities of Ilambda(2)=2 x 10(18) W microm(2)/cm(2). The thermal penetration depth is greater than the foil thickness in these targets so that uniform heating takes place at constant density before hydrodynamic motion occurs. The high-contrast, high-intensity laser pulse, broad spectral band, and short time resolution utilized in this experiment permit a simplified interpretation of the dynamical evolution of the radiating matter. The observed spectrum displays two distinct phases. At early time, < or =500 fs after detecting target emission, a broad quasicontinuous spectral feature with strong satellite emission from multiply excited levels is seen. At a later time, the He-like resonance line emission is dominant. The time-integrated data is in accord with previous studies with time resolution greater than 1 ps. The early time satellite emission is shown to be a signature of an initial large area, high density, low-temperature plasma created in the foil by fast electrons accelerated by the intense radiation field in the laser spot. We conclude that, because of this early time phenomenon and contrary to previous predictions, a short, high-intensity laser pulse incident on a thin foil does not create a uniform hot and dense plasma. The heating mechanism has been studied as a function of foil thickness, laser pulse length, and intensity. In addition, the spectra are found to be in broad agreement with a hydrodynamic expansion code postprocessed by a collisional-radiative model based on superconfiguration average rates and on the unresolved transition array formalism. PMID:12513417

Audebert, P; Shepherd, R; Fournier, K B; Peyrusse, O; Price, D; Lee, R W; Springer, P; Gauthier, J-C; Klein, L

2002-12-01

390

Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.  

PubMed

A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25. PMID:24191478

Lv, Jinze; Zhu, Lizhong

2013-01-01

391

Caterpillars selected for large body size and short development time are more susceptible to oxygen-related stress  

PubMed Central

Recent studies suggest that higher growth rates may be associated with reduced capacities for stress tolerance and increased accumulated damage due to reactive oxygen species. We tested the response of Manduca sexta (Sphingidae) lines selected for large or small body size and short development time to hypoxia (10 kPa) and hyperoxia (25, 33, and 40 kPa); both hypoxia and hyperoxia reduce reproduction and oxygen levels over 33 kPa have been shown to increase oxidative damage in insects. Under normoxic (21 kPa) conditions, individuals from the large-selected (big-fast) line were larger and had faster growth rates, slightly longer developmental times, and reduced survival rates compared to individuals from a line selected for small size (small-fast) or an unselected control line. Individuals from the big-fast line exhibited greater negative responses to hyperoxia with greater reductions in juvenile and adult mass, growth rate, and survival than the other two lines. Hypoxia generally negatively affected survival and growth/size, but the lines responded similarly. These results are mostly consistent with the hypothesis that simultaneous acquisition of large body sizes and short development times leads to reduced capacities for coping with stressful conditions including oxidative damage. This result is of particular importance in that natural selection tends to decrease development time and increase body size.

Harrison, Jon F; Cease, Arianne J; VandenBrooks, John M; Albert, Todd; Davidowitz, Goggy

2013-01-01

392

A numerical study of short residence time FCC riser flows with a new flow/kinetics modeling technique.  

SciTech Connect

Fluid Catalytic Cracking (FCC) technology is the most important process used by the refinery industry to convert crude oil to valuable lighter products such as gasoline. New and modified processes are constantly developed by refinery companies to improve their global competitiveness and meet more stringent environmental regulations. Short residence time FCC riser reactor is one of the advanced processes that the refining industry is actively pursuing because it can improve the yield selectivity and efficiency of an FCC unit. However, as the residence time becomes shorter, the impact of the mixing between catalyst and feed oil at the feed injection region on the product yield becomes more significant. Currently, most FCC computer models used by the refineries perform sophisticated kinetic calculations on simplified flow field and can not be used to evaluate the impact of fluid mixing on the performance of an FCC unit. Argonne National Laboratory (AFL) is developing a computational fluid dynamic (CFD) code ICRKFLO for FCC riser flow modeling. The code, employing hybrid hydrodynamic-chemical kinetic coupling techniques, is used to investigate the effect of operating and design conditions on the product yields of FCC riser reactors. Numerical calculations were made using the code to examine the impacts of the operating and design conditions on the product yields. The controlling parameters under investigation include the residence time, reaction temperature, and catalyst/oil ratio. This paper describes the CFD code, presents computation results, and discusses the effects of operating conditions on the performance of short residence time FCC riser reactors.

Chang, S. L.

1998-08-25

393

An investigation of short period oscillations of the solar irradiance and their time variations  

NASA Technical Reports Server (NTRS)

Measurements of solar irradiance fluctuations by the Active Cavity Radiometer (ACRIM) instrument onboard the Solar Maximum Mission (SMM) show variations on a time scale of about 5 minutes due to solar p-mode oscillations, as well as longer-term variations related to solar magnetic activity. The question was studied whether the p-mode frequencies change with time as a result of changing solar structure associated with the activity cycle. The ACRIM data on SMM are particularly well-suited for this purpose, because the instrument operated continuously from February 1980 to December 1980 and again from May 1984 to the present. The main activity entailed a detailed study of the observational data to determine if a change in the p-mode frequencies is evident from the time of solar maximum to that of solar minimum. It was concluded that the measured eigenfrequencies were significantly higher during the 1980 time frame than during the 1984 to 1986 time frame. The conclusion that there is significant change in the eigenfrequencies with the activity cycle remains only tentative, and needs confirmation from analysis of more data during the upcoming solar maximum.

Noyes, Robert W.

1987-01-01

394

Potential denitrification and N2O efflux from riparian soils during short-time flooding  

NASA Astrophysics Data System (ADS)

Denitrification can contribute significantly to the filter function of soils because it leads to permanent removal of nitrate. Denitrification has been intensively studied in wetlands characterized by seasonal wet-dry cycles and in riparian buffer zones between agricultural land and rivers. Less attention has been paid to the effects of overbank flooding in river floodplains, in particular to short terms effect of flood pulses. We monitored denitrification potential, N2O efflux and related parameters in soils of a restored reach of the Alpine river Thur in northeastern Switzerland during and after flashy flood events. The study was part of the interdisciplinary project cluster RECORD, which was initiated to advance the mechanistic understanding of coupled hydrological and ecological processes in river corridors. The studied river reach comprised the following three functional processing zones (FPZ) representing a lateral successional gradient with decreasing hydrological connectivity (i.e. decreasing flooding frequency and duration). (i) The grass zone developed naturally on a gravel bar after restoration of the channelized river section (mainly colonized by canary reed grass Phalaris arundinacae). The soil is composed of up to 80 cm thick fresh sediments trapped and stabilized by the grass roots. (ii) The bush zone is composed of young willow trees (Salix viminalis) planted during restoration to stabilize older overbank deposits. (iii) The mixed forest is a mature riparian hardwood forest developed on older overbank sediments with ash and maple as dominant trees. The study period was between April and October 2009 including two flood events in June and July. The first flood inundated the grass zone and lower part of the willow bush while the second bigger flood swept through all the FPZs. Topsoil samples were taken from four spatial replicates in each FPZ mostly biweekly and with higher frequency following the floods. Potential denitrification was measured as denitrifier enzyme activity (DEA) and substrate limitation was assessed by the same assay but without addition of glucose and nitrate. Over the entire observation period, soil moisture was the main controlling factor of DEA in all FPZ (correlation between DEA and gravimetric water content with R = 0.74, 0.61 and 0.47 for grass zone, willow bush and mixed forest, respectively, at p<0.01). Considering extractable nitrate and the results from the denitrification assay without nitrate and glucose we conclude that there was some substrate limitation but it was not severe. During the flooding events, DEA responded instantaneously to the changes in soil moisture. Particularly strong denitrification "pulses" were observed 1 to 2 days after peak floods in the grass zone, while the scale of change decreased with distance from the river. A severe substrate limitation in the grass zone was indicated 5 days after the peak of the second flood. N2O emissions did not correlate with DEA. High N2O emissions were measured in the grass zone during the entire period of relatively high soil moisture encompassing the two floods with maximum values shortly after water level fell below the overbank sediment. Smaller N2O emissions during complete or partial saturation of the sediments indicated a smaller proportion of denitrification related N2O vs. N2. In addition, a comparison with the composition of soil solution collected in-situ (in particular nitrate and DOC) will be presented for additional insight into controls and limitations of denitrification.

Shrestha, Juna; Niklaus, Pascal; Frossard, Emmanuel; Tockner, Klement; Luster, Jörg

2010-05-01

395

Double short-time exposure to pirarubicin produces higher cytotoxicity against T24 bladder cancer cells.  

PubMed

This study was designed to determine the ideal manner (schedule and duration) of intravesical chemotherapy using pirarubicin (THP). At first, T-24 cancer cells were treated with 50, 100, 150, and 200 ?g/ml THP for 10, 30 and 60 min. Following the first exposure, at various intervals (3, 6, 12, and 24 h), a second exposure to THP was performed under the same condition in vitro. The cell viability was measured by XTT assay. Further, the cells were scanned with a laser scanning cytometer (LSC) and DNA histograms were analyzed to evaluate the cell-cycle components. A single exposure of T-24 cells to THP resulted in significantly higher inhibition of cell growth for 30 min with 100 ?g/ml and higher concentrations of THP; for example, the cell viability was reduced to 15, 2, and 0% by incubating cells with 100, 150, and 200 ?g/ml of THP, respectively, whereas it was 49% with 50 ?g/ml THP. Double exposure of T-24 cells to THP resulted in significantly higher inhibition of cell growth than single treatment at all intervals. LSC assay demonstrated a higher sub-G(1) peak after double treatment with THP when compared with that after a single treatment. Similar cytotoxic effects following double treatment with THP were observed on other bladder cancer cell lines (UMUC3, TCCSUP, 5637, and 253J cells) in vitro. In conclusion, the double short-term exposure to bladder cancer cells by THP has more remarkable cytotoxic effects than the single exposure in vitro. PMID:20632198

Maruyama, Takuo; Higuchi, Yoshihide; Suzuki, Toru; Qiu, Jun; Yamamoto, Shingo; Shima, Hiroki

2011-02-01

396

Inspiratory-phase short time scale synchrony in the brainstem slice is generated downstream of the pre-Bötzinger complex.  

PubMed

Respiratory neurons are synchronized on a long time scale to generate inspiratory and expiratory-phase activities that are critical for respiration. Long time scale synchrony within the respiratory network occurs on a time scale of more than hundreds of milliseconds to seconds. During inspiration, neurons are synchronized on a short time scale to produce synchronous oscillations, which shape the pattern of inspiratory motor output. This latter form of synchrony within the respiratory network spans a shorter time range of tens of milliseconds. In the neonatal mouse rhythmically active medullary slice preparation, we recorded bilateral inspiratory activity from hypoglossal (XII) rootlets to study where in the slice synchronous oscillations are generated. Based on previous work that proposed the origin of these oscillations, we tested the pre-Bötzinger complex (PreBötC) and the XII motor nucleus. Unilateral excitation of the PreBötC, via local application of a perfusate containing high K(+), increased mean inspiratory burst frequency bilaterally (296+/-66%; n=10, P<0.01), but had no effect on the relative power of oscillations. In contrast, unilateral excitation of the XII nucleus increased both mean peak integrated activity bilaterally (ipsilateral: 41+/-10%, P<0.01; contralateral: 17+/-7%; P<0.05, n=10) and oscillation power in the ipsilateral (50+/-17%, n=7, P<0.05), but not in the contralateral rootlet. Cross-correlation analysis of control inspiratory activity recorded from the left and right XII rootlets produced cross-correlation histograms with significant peaks centered around a time lag of zero and showed no subsidiary harmonic peaks. Coherence analysis of left and right XII rootlet recordings demonstrated that oscillations are only weakly coherent. Together, the findings from local application experiments and cross-correlation and coherence analyses indicate that short time scale synchronous oscillations recorded in the slice are likely generated in or immediately upstream of the XII motor nucleus. PMID:18455877

Sebe, J Y; Berger, A J

2008-06-01

397

New solutions for the short-time analysis of geothermal vertical boreholes  

Microsoft Academic Search

Many models, either numerical or analytical, have been proposed to analyse the thermal response of vertical heat exchangers that are used in ground coupled heat pump systems (GCHP). In both approaches, most of the models are valid after few hours of operation since they neglect the heat capacity of the borehole. This is valid for design purposes, where the time

Louis Lamarche; Benoit Beauchamp

2007-01-01

398

Economic Incentives of Short out-of-Reactor Time for Fast Breeder Reactor Fuel.  

National Technical Information Service (NTIS)

Economic benefits (primarily reduced uranium ore and enrichment expenditures) can be realized by reducing the LMFBR out-of-reactor fuel cycle time only if process cost penalties and R and D costs can be minimized. The results of the evaluation presented s...

B. W. Bentley, D. R. Haffner

1975-01-01

399

Estimation of impulse response of Earth's climate system at short time intervals  

NASA Astrophysics Data System (ADS)

A method is described for restoration of the impulse response h(t) of the Earth's climate system (ECS), which is regarded as a time-invariant linear dynamic system whose input is the change in solar constant, and output—the global mean surface temperature anomalies. Search for solution of the ill-posed inverse problem is carried out on a compact set of non-negative, monotonically non-increasing, convex downward functions. This suggests that ECS may be a first-order dynamic system or a set of similar independent subsystems with different time constants. Results of restoration of h(t) at time intervals up to 100 months show that it is a rapidly decreasing function, which does not differ from zero for t>3 months. An estimate of the equivalent time constant gives the average value of 1.04±0.17 months. The sensitivity of the ECS to changes in radiative forcing at the top of the atmosphere is equal to 0.41±0.05 K W-1 m2.

Bogdanov, M. B.; Efremova, T. Yu.; Katrushchenko, A. V.

2012-09-01

400

Development of a restructured alginate food particle suitable for high temperature-short time process validation  

Microsoft Academic Search

Cylindrical particles of alginate and alginate\\/starch food purée were developed for use as carriers in a microbiological time temperature integrator (TTI). The mechanical properties of the restructured food particle, stress (?f) and strain at failure (?f), were studied as a function of different composition parameters (alginate and food concentration, pH, type offood added, and addition of starch). Addition of food

M. J. Ocio; S. M. Fiszman; F. Gasque; M. Rodrigo; A. Martinez

1997-01-01

401

Short-Time Events, Coherence, and Structural Dynamics in Photochemistry of Aqueous Halogenated Transition Metal Dianions  

NASA Astrophysics Data System (ADS)

Ultrafast pump-probe spectroscopy, time-resolved x-ray absorption, and computational photochemistry elucidate the photochemical pathway of hexabromoplatinate dianions that propagates through distortions of nascent penta-bromoplatinate anions caused by Jahn-Teller conical intersections and terminates at aquated product complexes.

Tarnovsky, A. N.; Zheldakov, I. L.; El-Khoury, P. Z.; Pal, S. K.; Mereshchenko, A. S.; Ryazantsev, M. N.; Butaeva, E. V.; Pascher, T.; Uhlig, J.; Milne, C. J.; Johnson, S. L.

2013-03-01

402

Autocorrelation Effects on Least-Squares Intervention Analysis of Short Time Series.  

ERIC Educational Resources Information Center

Clarifies several issues regarding the effects of autocorrelated errors on Type I error in ordinary least-squares models. Demonstrates through Monte Carlo simulation the conditions under which distortion in Type I error is less than predicted by asymptotic theory. Suggests a recently developed small-sample method for time-series analyses. (SLD)

Huitema, Bradley E.; McKean, Joseph W.; McKnight, Scott

1999-01-01

403

Short-time-scale self-focusing of electromagnetic beams in a magnetoplasma  

Microsoft Academic Search

A Gaussian electromagnetic beam propagating in a plasma in the direction of the static magnetic field gives rise to (1) a ponderomotive force transverse to the magnetic field and (2) nonuniform heating of electrons. These effects eventually modify the local magnetic field and thus produce a nonlinearity relevant to self-focusing. The critical power for self-focusing on a time scale shorter

D. P. Tewari; R. R. Sharma

1979-01-01

404

Uhuru observations of short-time-scale variations of the Crab. [X ray emission from pulsar  

NASA Technical Reports Server (NTRS)

We have analyzed Uhuru X-ray observations of the Crab and found statistically significant variability in the intensity on time scales of several tenths of a second. Our results imply either that the X-ray emission from the pulsar NP 0532 is highly variable or that we have observed a previously undetected compact source of X-rays.

Forman, W.; Giacconi, R.; Jones, C.; Schreier, E.; Tananbaum, H.

1974-01-01

405

Gaussian Mixture Modeling Using Short Time Fourier Transform Features for Audio Fingerprinting  

Microsoft Academic Search

In audio fingerprinting, an audio clip must be recognized by matching an extracted fingerprint to a database of previously computed fingerprints. The fingerprints should reduce the dimensionality of the input significantly, provide discrimination among different audio clips, and at the same time, invariant to the distorted versions of the same audio clip. In this paper, we design fingerprints addressing the

Arunan Ramalingam; Sridhar Krishnan

2005-01-01

406

Gaussian Mixture Modeling of Short-Time Fourier Transform Features for Audio Fingerprinting  

Microsoft Academic Search

In audio fingerprinting, an audio clip must be recognized by matching an extracted fingerprint to a database of previously computed fingerprints. The fingerprints should reduce the dimensionality of the input significantly, provide discrimination among different audio clips, and, at the same time, be invariant to distorted versions of the same audio clip. In this paper, we design fingerprints addressing the

Arunan Ramalingam; Sridhar Krishnan

2006-01-01

407

Effects of time-of-day and partial sleep deprivation on short-term maximal performances of judo competitors.  

PubMed

This study assessed the effects of partial sleep deprivation on short-term maximal performances of judokas in the morning and afternoon of the following day. In a randomized design, 12 judokas completed the maximal voluntary contraction, the handgrip, and the Wingate tests before and after a judo combat. Measurements were performed at 09:00 and 16:00 hours after a reference-normal sleep night and 2 conditions of 4-hour partial sleep deprivation timed at the beginning (SDB) or at the end of the night (SDE). The results showed that muscle power and strength were significantly higher at 16:00 than 09:00 hours (p < 0.05). These diurnal variations disappeared after SDB and SDE and after the combat. In addition, SDE resulted in significant decreases of short-term maximal performance in the afternoon (p < 0.01). In conclusion, SDE decreased muscle strength and power at 16:00 hours and, therefore, might have blunted the diurnal variations of short-term maximal exercise. Thus, early rising is more detrimental than late bedtime to muscle strength and power for judo athletes when competitions are scheduled in the afternoon hours. PMID:23974210

Souissi, Nizar; Chtourou, Hamdi; Aloui, Asma; Hammouda, Omar; Dogui, Mohamed; Chaouachi, Anis; Chamari, Karim

2013-09-01

408

Identifying monomer phases and cluster phases in lysozyme solutions by studying the temperature dependence of the short-time dynamics  

SciTech Connect

Recently experiments that combine both small angle neutron scattering (SANS) and Neutron Spin Echo (NSE) have demonstrated that dynamic clusters can form in concentrated lysozyme solutions when there is a right combination of a short-ranged attraction and a long-ranged electrostatic repulsion. In this paper, we study the temperature effect on the dynamic cluster formation and try to pinpoint the transition concentration from a monomer phase to a cluster phase. Interestingly at even a relatively high concentration (10 % mass fraction), despite the significant change of the SANS patterns that are associated with the change of the short-ranged attraction among proteins, the normalized short-time self-diffusion coefficient is not affected. This is interpreted due to the fact that there is no cluster formation at this condition. However, at larger concentrations such as 17.5 % and 22.5 % mass fraction, we show that the average hydrodynamic radius increase significantly and causes a large decrease of the normalized self-diffusion coefficient when the temperature is changed from 25 oC to 5 oC indicating the formation of dynamic clusters in solution.

Baglioni, P [University of Florence; Chen, Wei-Ren [ORNL; Falus, Peter [ORNL; Faraone, Antonio [National Institute of Standards and Technology (NIST); Fratini, Emiliano [University of Florence; Hong, Kunlun [ORNL; Liu, Yun [National Institute of Standards and Technology (NIST); Porcar, L. [National Institute of Standards and Technology (NIST)

2012-01-01

409

Short communication: Timing of first milking affects serotonin (5-HT) concentrations.  

PubMed

Hormonal signals differentially regulate the timing of parturition, as well lactogenesis and, potentially, colostrum formation in the mammary gland. Non-neuronal serotonin (5-HT) is a homeostatic regulator of the mammary gland. In the current study, we manipulated the timing of first milking to investigate its effects on serum 5-HT and calcium concentrations in the maternal and calf circulation, as well as in colostrum. Twenty-three cows were randomly assigned to a control (CON; n=10) group, milked for the first time at 4h postcalving, or a treatment (TRT; n=13) group, milked for the first time approximately 1 d before calving in addition to 4h postcalving. Maternal blood samples were collected for 4 d precalving, 3 times daily, and 1 blood sample was taken 4h postcalving. Calf blood samples were collected 4 (before first colostrum feeding) and 12h after birth, and at 3wk of age. Calves from both treatments were fed colostrum from their respective mothers. Serum 5-HT concentrations were greater in CON cows and decreased significantly in TRT cows after milking was initiated precalving (951 vs. 524±111ng/mL, respectively). Cow serum calcium concentrations were affected by time, beginning to decrease 1 d precalving until 4h postcalving, but this drop in serum calcium was more pronounced in TRT cows. Serum 5-HT and calcium concentrations were negatively correlated (r=-0.57) for the CON cows and positively correlated (r=0.6) for the TRT cows. Maternal calcium and 5-HT decreased similarly due to precalving milking. Calcium and 5-HT concentrations were greater in colostrum collected from TRT cows milked precalving. Overall, calves had higher circulating 5-HT concentrations than cows, and calves born to TRT cows had increased 5-HT concentrations compared with the CON. Precalving milking could affect 5-HT synthesis within the mammary gland and therefore affect maternal 5-HT and calcium concentrations. Further research is needed in ruminants to assess the extent of 5-HT placental transfer, its role on pre- and postnatal development of the calf, the importance of its presence in colostrum, and potential long-term effects on calf health. PMID:24612806

Laporta, J; Gross, J J; Crenshaw, T D; Bruckmaier, R M; Hernandez, L L

2014-05-01

410

Effects of long and short relaxation times of particle interactions in dense and slow granular flows  

SciTech Connect

In this work, dense granular flows are numerically simulated using a discrete element method. The interaction of a pair of colliding particles is modeled as a parallel connection of a linear spring and a linear dashpot. Although the force model for particle interactions is simplistic for many practical problems, a significant amount of meaningful new physics can be extracted from the numerical simulations by studying the behavior of particle interaction time and its probability distribution. For instance, it is found that the probability distribution of particle contact ages is exponential for long-term contacts. The time scale of the exponential decay of the contact age probability is related to the rheological properties of the dense granular medium.

Zhang, D. Z. (Duan Z.); Rauenzahn, Rick M.

2002-01-01

411

Test of the exponential decay law at short decay times using tau leptons  

NASA Astrophysics Data System (ADS)

Quantum mechanics predicts an exponential distribution for the decay time of massive particles. However, deviations are expected for decay times shorter than about 10 -13 s in models conjecturing the existence of hidden variables. Following a recent proposal, the decay length distribution of 5843 ? leptons decaying into 3 charged particles was analyzed in search of such a deviation. The deviation from an exponential distribution with respect to the number of decays present within the exponential form, expressed as the relative weight of an excess at zero decay length, was measured to be 1.1%±1.4%±3.5%. This result is consistent with zero deviation and leads to an upper limit of 8.5% and a lower limit of -6.3% at the 95% confidence level.

Alexander, G.; Allison, J.; Altekamp, N.; Ametewee, K.; Anderson, K. J.; Anderson, S.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Ball, A. H.; Barberio, E.; Barlow, R. J.; Bartoldus, R.; Batley, J. R.; Beaudoin, G.; Bechtluft, J.; Beck, G. A.; Beeston, C.; Behnke, T.; Bell, A. N.; Bell, K. W.; Bella, G.; Bentvelsen, S.; Berlich, P.; Bethke, S.; Biebel, O.; Bloodworth, I. J.; Bloomer, J. E.; Bock, P.; Bosch, H. M.; Boutemeur, M.; Bouwens, B. T.; Braibant, S.; Bright-Thomas, P.; Brown, R. M.; Burckhart, H. J.; Burgard, C.; Bürgin, R.; Capiluppi, P.; Carnegie, R. K.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlesworth, C.; Charlton, D. G.; Chrisman, D.; Chu, S. L.; Clarke, P. E. L.; Clowes, S. G.; Cohen, I.; Conboy, J. E.; Cooke, O. C.; Cuffiani, M.; Dado, S.; Dallapiccola, C.; Dallavalle, G. M.; Darling, C.; De Jong, S.; del Pozo, L. A.; Dixit, M. S.; do Couto e Silva, E.; Duchovni, E.; Duckeck, G.; Duerdoth, I. P.; Dunwoody, U. C.; Edwards, J. E. G.; Estabrooks, P. G.; Evans, H. G.; Fabbri, F.; Fabbro, B.; Fath, P.; Fiedler, F.; Fierro, M.; Fincke-Keeler, M.; Fischer, H. M.; Folman, R.; Fong, D. G.; Foucher, M.; Fukui, H.; Fürtjes, A.; Gagnon, P.; Gaidot, A.; Gary, J. W.; Gascon, J.; Gascon-Shotkin, S. M.; Geddes, N. I.; Geich-Gimbel, C.; Gensler, S. W.; Gentit, F. X.; Geralis, T.; Giacomelli, G.; Giacomelli, P.; Giacomelli, R.; Gibson, V.; Gibson, W. R.; Gingrich, D. M.; Goldberg, J.; Goodrick, M. J.; Gorn, W.; Grandi, C.; Gross, E.; Hajdu, C.; Hanson, G. G.; Hansroul, M.; Hapke, M.; Hargrove, C. K.; Hart, P. A.; Hartmann, C.; Hauschild, M.; Hawkes, C. M.; Hawkings, R.; Hemingway, R. J.; Herten, G.; Heuer, R. D.; Hildreth, M. D.; Hill, J. C.; Hillier, S. J.; Hilse, T.; Hobson, P. R.; Hochman, D.; Homer, R. J.; Honma, A. K.; Horváth, D.; Howard, R.; Hughes-Jones, R. E.; Hutchcroft, D. E.; Igo-Kemenes, P.; Imrie, D. C.; Jawahery, A.; Jeffreys, P. W.; Jeremie, H.; Jimack, M.; Joly, A.; Jones, M.; Jones, R. W. L.; Jost, U.; Jovanovic, P.; Karlen, D.; Kawamoto, T.; Keeler, R. K.; Kellogg, R. G.; Kennedy, B. W.; King, B. J.; King, J.; Kirk, J.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D. S.; Kokott, T. P.; Komamiya, S.; Kowalewski, R.; Kress, T.; Krieger, P.; von Krogh, J.; Kyberd, P.; Lafferty, G. D.; Lafoux, H.; Lahmann, R.; Lai, W. P.; Lanske, D.; Lauber, J.; Layter, J. G.; Lee, A. M.; Lefebvre, E.; Lellouch, D.; Letts, J.; Levinson, L.; Lewis, C.; Lloyd, S. L.; Loebinger, F. K.; Long, G. D.; Lorazo, B.; Losty, M. J.; Ludwig, J.; Luig, A.; Malik, A.; Mannelli, M.; Marcellini, S.; Markus, C.; Martin, A. J.; Martin, J. P.; Martinez, G.; Mashimo, T.; Matthews, W.; Mättig, P.; McDonald, W. J.; McKenna, J.; Mckigney, E. A.; McMahon, T. J.; McNab, A. I.; Meijers, F.; Menke, S.; Merritt, F. S.; Mes, H.; Meyer, J.; Michelini, A.; Mikenberg, G.; Miller, D. J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Morii, M.; Müller, U.; Nellen, B.; Nijjhar, B.; Nisius, R.; O'Neale, S. W.; Oakham, F. G.; Odorici, F.; Ogren, H. O.; Oldershaw, N. J.; Omori, T.; Oram, C. J.; Oreglia, M. J.; Orito, S.; Palazzo, M.; Pálinkás, J.; Palmonari, F. M.; Pansart, J. P.; Pásztor, G.; Pater, J. R.; Patrick, G. N.; Pearce, M. J.; Phillips, P. D.; Pilcher, J. E.; Pinfold, J.; Plane, D. E.; Poffenberger, P.; Poli, B.; Posthaus, A.; Pritchard, T. W.; Przysiezniak, H.; Rees, D. L.; Rigby, D.; Rison, M. G.; Robins, S. A.; Rodning, N.; Roney, J. M.; Ros, E.; Rossi, A. M.; Rosvick, M.; Routenburg, P.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D. R.; Rylko, R.; Sarkisyan, E. K. G.; Sasaki, M.; Sbarra, C.; Schaile, A. D.; Schaile, O.; Scharf, F.; Scharff-Hansen, P.; Schenk, P.; Schmitt, B.; Schröder, M.; Schultz-Coulon, H. C.; Schulz, M.; Schütz, P.; Schwiening, J.; Scott, W. G.; Shears, T. G.; Shen, B. C.; Shepherd-Themistocleous, C. H.; Sherwood, P.; Siroli, G. P.; Sittler, A.; Skillman, A.; Skuja, A.; Smith, A. M.; Smith, T. J.; Snow, G. A.; Sobie, R.; Söldner-Rembold, S.; Springer, R. W.; Sproston, M.; Stahl, A.; Starks, M.; Stegmann, C.; Stephens, K.; Steuerer, J.; Stockhausen, B.; Strom, D.; Strumia, F.; Szymanski, P.; Tafirout, R.; Takeda, H.; Taras, P.; Tarem, S.; Tecchio, M.; Tesch, N.; Thomson, M. A.; von Törne, E.; Towers, S.; Tscheulin, M.; Tsukamoto, T.; Tsur, E.; Turcot, A. S.; Turner-Watson, M. F.; Utzat, P.; Van Kooten, R.; Vasseur, G.; Vikas, P.; Vincter, M.; Vokurka, E. H.; Wäckerle, F.; Wagner, A.; Wagner, D. L.; Ward, C. P.; Ward, D. R.; Ward, J. J.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Weber, P.; Wells, P. S.; Wermes, N.; Wilkens, B.; Wilson, G. W.; Wilson, J. A.; Wlodek, T.; Wolf, G.; Wotton, S.; Wyatt, T. R.; Xella, S.; Yamashita, S.; Yekutieli, G.; Zacek, V.; OPAL Collaboration

1996-02-01

412

New short-time alignment technique for 70-meter antenna surface panels  

NASA Technical Reports Server (NTRS)

With severely limited field modification time for upgrading the 64-m antenna to 70-m diameter, a new shorter time method for aligning the surface panels of the main reflector was needed. For each target on the surface panel, both distance (or range) and elevation angle measurements are made. A new technique for setting the surface panels at zenith look has been devised. This article describes the software required to convert the computed target distortions obtained from the JPL-IDEAS structural analysis computer program (defining the gravity load change from a 45-deg elevation angle to zenith look) into the theodolite reading at zenith look. The technique results in a perfectly shaped reflector at the 45-deg rigging elevation, with acceptable surface error tolerance.

Katow, M. S.

1986-01-01

413

Radionuclide inventories for short run-time space nuclear reactor systems  

SciTech Connect

Space Nuclear Reactor Systems, especially those used for propulsion, often have expected operation run times much shorter than those for land-based nuclear power plants. This produces substantially different radionuclide inventories to be considered in the safety analyses of space nuclear systems. This presentation describes an analysis utilizing ORIGEN2 and DKPOWER to provide comparisons among representative land-based and space systems. These comparisons enable early, conceptual considerations of safety issues and features in the preliminary design phases of operational systems, test facilities, and operations by identifying differences between the requirements for space systems and the established practice for land-based power systems. Early indications are that separation distance is much more effective as a safety measure for space nuclear systems than for power reactors because greater decay of the radionuclide activity occurs during the time to transport the inventory a given distance. In addition, the inventories of long-lived actinides are very low for space reactor systems.

Coats, R.L.

1992-10-22

414

Multi-reflection time-of-flight mass spectrograph for short-lived radioactive ions  

Microsoft Academic Search

RIKEN’s new RI-Beam Factory (RIBF) will provide unprecedented access to neutron-rich nuclei of importance to r-process nucleosynthesis.\\u000a We are constructing an advanced multi-reflection time-of-flight mass spectrograph to perform precision mass measurements of\\u000a these nuclei. We discuss the device and compare its performance to that of the well-known Penning trap mass spectrometer.

P. Schury; K. Okada; S. Shchepunov; T. Sonoda; A. Takamine; M. Wada; H. Wollnik; Y. Yamazaki

2009-01-01

415

Multi-reflection time-of-flight mass spectrograph for short-lived radioactive ions  

NASA Astrophysics Data System (ADS)

RIKEN’s new RI-Beam Factory (RIBF) will provide unprecedented access to neutron-rich nuclei of importance to r-process nucleosynthesis. We are constructing an advanced multi-reflection time-of-flight mass spectrograph to perform precision mass measurements of these nuclei. We discuss the device and compare its performance to that of the well-known Penning trap mass spectrometer.

Schury, P.; Okada, K.; Shchepunov, S.; Sonoda, T.; Takamine, A.; Wada, M.; Wollnik, H.; Yamazaki, Y.

2009-12-01

416

Short time ionic liquids pretreatment on lignocellulosic biomass to enhance enzymatic saccharification  

Microsoft Academic Search

The potential of 1-buthyl-3-methylpyridinium chloride, [Bmpy][Cl], as a pretreatment solvent for lignocellulosic biomasses, Bagasse and Eucalyptus, was investigated. The yields of regenerated biomasses ranged between 35% and 96%, and varied according to the pretreatment time, type of ionic liquid (IL) and biomass. The pretreatment of the biomass with [Bmpy][Cl] resulted in up to 8-fold increase in the cellulose conversion when

Uju; Yasuhiro Shoda; Aya Nakamoto; Masahiro Goto; Wataru Tokuhara; Yoshiyuki Noritake; Satoshi Katahira; Nobuhiro Ishida; Kazunori Nakashima; Chiaki Ogino; Noriho Kamiya

417

Short-time-scale variations in flow speed and behavior, Helheim Glacier, East Greenland  

Microsoft Academic Search

We have obtained a suite of detailed geophysical observations, spanning two summer seasons, at Helheim Glacier, East Greenland. This interdisciplinary dataset includes geodetic, seismic, radar, and lidar observations, in addition to tidal, weather, and satellite remote-sensing data. Continuous high-rate GPS observations from a period of 50 days in July--August, 2007, extend a 60-day summer-season time series obtained in 2006. Reoccupation

M. Nettles; T. B. Larsen; P. Elósegui; A. P. Ahlstrøm; J. L. Davis; J. de Juan; G. EkstrÖM; R. Forsberg; G. S. Hamilton; S. A. Khan; M. L. Andersen; L. A. Stearns; L. Stenseng

2007-01-01

418

Magnetization dynamics in the inertial regime: nutation predicted at short time scales  

Microsoft Academic Search

The dynamical equation of the magnetization has been reconsidered with\\u000aenlarging the phase space of the ferromagnetic degrees of freedom to the\\u000aangular momentum. The generalized Landau-Lifshitz-Gilbert equation that\\u000aincludes inertial terms, and the corresponding Fokker-Planck equation, are then\\u000aderived in the framework of mesoscopic non-equilibrium thermodynamics theory. A\\u000atypical relaxation time $\\\\tau$ is introduced describing the relaxation of the

M.-C. Ciornei; J. M. Rubí; J.-E. Wegrowe

2010-01-01

419

Magnetization dynamics in the inertial regime: Nutation predicted at short time scales  

Microsoft Academic Search

The dynamical equation for magnetization has been reconsidered by enlarging the phase space of the ferromagnetic degrees of freedom to the angular momentum. The generalized Landau-Lifshitz-Gilbert equation that includes inertial terms, and the corresponding Fokker-Planck equation, are then derived in the framework of mesoscopic nonequilibrium thermodynamics theory. A typical relaxation time tau is introduced describing the relaxation of the magnetization

M.-C. Ciornei; J. M. Rubí; J.-E. Wegrowe

2011-01-01

420

Time estimation and concurrent nontemporal processing: Specific interference from short-term-memory demands  

Microsoft Academic Search

Previous studies have shown that the effect of concurrent nontempcraLprocessmg on time astimation may vary depending on the\\u000a level of difficulty of the nontemporal task. This is commonly interpreted within the context of so-called distraction\\/interruption\\u000a models of temporal processing, which propose that as concurrent task difficulty or complexity is increased, temporal processing\\u000a receives less attention. We hypothesize that the effect

C. Fortin; R. Rousseau; P. Bourque; E. Kirouac

1993-01-01

421

Optimal short-time acquisition schemes in high angular resolution diffusion-weighted imaging.  

PubMed

This work investigates the possibilities of applying high-angular-resolution-diffusion-imaging- (HARDI-) based methods in a clinical setting by investigating the performance of non-Gaussian diffusion probability density function (PDF) estimation for a range of b-values and diffusion gradient direction tables. It does so at realistic SNR levels achievable in limited time on a high-performance 3T system for the whole human brain in vivo. We use both computational simulations and in vivo brain scans to quantify the angular resolution of two selected reconstruction methods: Q-ball imaging and the diffusion orientation transform. We propose a new analytical solution to the ODF derived from the DOT. Both techniques are analytical decomposition approaches that require identical acquisition and modest postprocessing times and, given the proposed modifications of the DOT, can be analyzed in a similar fashion. We find that an optimal HARDI protocol given a stringent time constraint (<10?min) combines a moderate b-value (around 2000?s/mm(2)) with a relatively low number of acquired directions (>48). Our findings generalize to other methods and additional improvements in MR acquisition techniques. PMID:23554808

Pr?kovska, V; Achterberg, H C; Bastiani, M; Pullens, P; Balmashnova, E; Ter Haar Romeny, B M; Vilanova, A; Roebroeck, A

2013-01-01

422

Real-time manned simulation of advanced terminal area guidance concepts for short-haul operations  

NASA Technical Reports Server (NTRS)

A real-time simulation was conducted of three-dimensional area navigation and four-dimensional area navigation equipped (STOL) aircraft operating in a high-density terminal area traffic environment. The objectives were to examine the effects of 3D RNAV and 4D RNAV equipped aircraft on the terminal area traffic efficiency, and to examine the performance of an air traffic control system concept and associated controller display proposed for use with advanced RNAV systems. Three types of STOL aircraft were simulated each with different performance capabilities. System performance was measured in both the 4D mode and in a 3D mode; the 3D mode, used as a baseline, was simply the 4D mode less any time specification. The results show that communications workload in the 4D mode was reduced by about 35 percent compared to the 3D, while 35 percent more traffic was handled with the 4D. Aircraft holding time in the 4D mode was only 30 percent of that required in the 3D mode. In addition, the orderliness of traffic was improved significantly in the 4D mode.

Tobias, L.; Obrien, P. J.

1977-01-01

423

Renormalization-group description of nonequilibrium critical short-time relaxation processes: A three-loop approximation  

SciTech Connect

The influence of nonequilibrium initial values of the order parameter on its evolution at a critical point is described using a renormalization group approach of the field theory. The dynamic critical exponent {theta} of the short time evolution of a system with an n-component order parameter is calculated within a dynamical dissipative model using the method of {sigma}-expansion in a three-loop approximation. Numerical values of {theta} for three-dimensional systems are determined using the Pade-Borel method for the summation of asymptotic series.

Prudnikov, V. V., E-mail: prudnikv@univer.omsk.su; Prudnikov, P. V.; Kalashnikov, I. A.; Tsirkin, S. S. [Omsk State University (Russian Federation)

2008-06-15

424

Direct growth of short single-walled carbon nanotubes with narrow-chirality distribution by time-programmed plasma chemical vapor deposition.  

PubMed

We have realized the direct growth of the short-length (<100 nm) single-walled carbon nanotubes (SWNTs) with a narrow-chirality distribution by time-programmed plasma chemical vapor deposition (TP-PCVD). Transmission electron microscope and atomic force microscope analyses reveal that the very short (<100 nm) SWNTs are selectively grown by precisely controlling their growth time on the order of a few seconds. Direct photoluminescence excitation measurements also show that the chirality distribution of the short SWNTs is fairly narrow, and (7, 6) and (8, 4) dominant short SWNTs are successfully synthesized by TP-PCVD. PMID:21082841

Kato, Toshiaki; Hatakeyama, Rikizo

2010-12-28

425

Finite frequency tomography: the checkerboard test revisited  

NASA Astrophysics Data System (ADS)

We address some consequences of the application of finite frequency theory for seismic tomography by revisiting the classical checkerboard test. We use a simple borehole-to-borehole experiment set-up in order to have complete control of the situation and to avoid complicating factors such as crustal corrections that still hamper global tomography. We are particularly interested in the feasibility of using ray-based finite frequency kernels in the inversion of travel time perturbations measured by crosscorrelation, in the cross-dependence between S wave velocity perturbations and the measured P travel times, and in the benefits of using finite-frequency theory on one or multiple frequency bands. We have done a 3D checkerboard test to assess the influence of these issues. Full-waveform synthetic seismograms are calculated using the spectral elements method up to 2 kHz maximum frequency. The computational domain extends 200 m x 120 m x 120 m and the target velocity model is a checkerboard with 12 m x 12 m x 12 m blocks of velocities 5% slower and faster than the background (homogeneous, Vp=6 km/s) model. First, we make a comparison between finite-frequency kernels calculated by ray theory with those based on the spectral elements method (adjoint technique), in terms of resolution, accuracy, but also computational cost. From synthetic seismograms calculated for the 3D checkerboard model as well as for the homogeneous model, we measure crosscorrelation travel times at different frequency bands and invert them with classical ray theory as well as with finite frequency theory. Several interesting features are highlighted in our multi-band data set, such as the wavefront healing effect. For instance, we observe that the delay times, in absolute value, are usually larger at short (0.5 ms) than long (4 ms) periods. This can be explained by the presence of the "doughnut hole" along the geometrical ray path in the sensitivity kernels, whose diameter is proportional to the period. Thus, as the period increases, the anomalies are able to "hide" inside the growing "doughnut hole". When a single frequency band is interpreted using ray theory (infinite frequency approximation), the fact that wavefront healing is not taken into account has a disastrous effect, in particular on the imaging of blocks that are somewhat smaller than the Fresnel zone. When interpreting the same data set with finite-frequency theory we do much better, especially in the center of the model where Fresnel zones are widest. Adding a range of frequencies in the inversion (i.e. taking body wave dispersion into account) significantly increases resolution.

Mercerat, E. D.; Zaroli, C.; Nolet, G.

2011-12-01

426

Improved nutrient removal using in situ continuous on-line sensors with short response time.  

PubMed

Nutrient sensors that can be located directly in the activated sludge processes are gaining in number at wastewater treatment plants. The in situ location of the sensors means that they can be located close to the processes that they aim to control and hence are perfectly suited for automatic process control. Compared to the location of automatic analysers in the effluent from the sedimentation reactors the in situ location means a large reduction in the response time. The settlers typically work as a first-order delay on the signal with a retention time in the range of 4-12 hours depending on the size of the settlers. Automatic process control of the nitrogen and phosphorus removal processes means that considerable improvements in the performance of aeration, internal recirculation, carbon dosage and phosphate precipitation dosage can be reached by using a simple control structure as well as simple PID controllers. The performance improvements can be seen in decreased energy and chemicals consumption and less variation in effluent concentrations of ammonium, total nitrogen and phosphate. Simple control schemes are demonstrated for the pre-denitrification and the post precipitation system by means of full-scale plant experiments and model simulations. PMID:12926625

Ingildsen, P; Wendelboe, H

2003-01-01

427

Time resolved holographic interferometry for short duration hypersonic high enthalpy test facilities  

NASA Astrophysics Data System (ADS)

The High Enthalpy Shock Tunnel Göttingen (HEG) of the German Aerospace Cen- ter (DLR) is one of the major European hypersonic test facilities. The HEG can operate over a wide range of test conditions, from low altitude high density Mach 6 flows through the simulation of Mach 8 flow at approximately 30 km altitude up to high enthalpy re-entry conditions. Full utilization of such ground based high enthalpy impulse facilities, with typical test times in the order of one to several milliseconds, requires detailed knowledge of the flow in the test section, and its starting processes. Further, the temporal development of the model flow must be known in order to assure that a steady flow has developed during the test time. For that reason a high speed flow visualization (HSFV) system has been implemented at HEG using the schlieren and shadowgraph technique. This paper describes a feasibility study undertaken to extend the optical measurement capabilities of the HEG by combining the HSFV system with the phase step holographic interferometry (HI) system used so far in single shot mode.

Martinez Schramm, J.; Boutry, A.; Vital Durand, M.; Hannemann, K.

428

Radiolytic Cryovolcanism Revisited  

NASA Astrophysics Data System (ADS)

Active geysers of water vapor and ice grains from the south pole of Enceladus are not yet definitively explained in terms of energy sources and processes. Other instances of hot (Io) and cold (Mars, Triton) volcanism beyond Earth are known if not fully understood. We revisit, in comparison to other models, the 'Old Faithful' theory of radiolytic gas-driven cryovolcanism first proposed by Cooper et al. [Plan. Sp. Sci. 2009]. In the energetic electron irradiation environment of Enceladus within Saturn's magnetosphere, a 10-percent duty cycle could be maintained for current geyser activity driven by gases from oxidation of ammonia to N2 and methane to CO2 in the thermal margins of a south polar sea. Much shorter duty cycles down to 0.01 percent would be required to account for thermal power output up to 16 GW, Steady accumulation of oxidant energy over four billion years could have powered all Enceladus emissions over the past four hundred thousand to four hundred million years. There could be separate energy sources driving mass flow and thermal emission over vastly different time scales. Since episodic tidal dissipation on 10 Myr time scales at 0.1 - 1 Gyr intervals [O'Neill and Nimmo, Nature 2010], and thus duty cycles 1 - 10 percent, could heat the polar sea to the current level, the radiolytic energy source could easily power and modulate the geyser mass flow on million-year time scales. Maximum thermal emission temperature 223 K [Abramov and Spencer, Icarus 2009] hints at thermal buffering in the basal and vent wall layers by a 1:1 H2O:H2O2 radiolytic eutectic, assuming deep ice crust saturation with H2O2 from long cumulative surface irradiation and downward ice convection. Due to density stratification the peroxide eutectic and salt water layers could separate, so that the denser peroxide layer (1.2 g/cc) descends to the polar sea while the lighter salt water (1.05 g/cc) rises along separate channels. Methane reservoirs could be found dissolved into the polar sea, or else trapped in hydrates [Kieffer et al., Science 2006] along flow paths and at the walls of the polar sea at surface depths below 20 km [Fortes, Icarus 2007]. Driver gas production for cryovolcanism could occur wherever these two layers come into contact under requisite temperature and pressure conditions, e.g. from 220 K and 10 bar at the 10-km basal layer of the overlying ice crust to 647 K and 220 bars at the liquid water limit, above the core-mantle boundary at 460 bars [Fortes, Icarus 2007]. We expect H2O2 oxidation to ignite at high temperatures but metallic minerals could catalyze reactions at lower temperatures nearer the basal layer. Pressure effects on oxidation rates are uncertain. Definitive modeling of Enceladus cryovolcanism likely involves synthesis of key processes from multiple models: Cold Faithful [Porco et al., Science 2006], Frigid Faithful [Keiffer et al., Science 2006], Frothy Faithful [Fortes, Icarus 2007], Old Faithful, and 'Perrier Ocean' recirculation [Matson et al., Icarus 2012].

Cooper, J. F.; Cooper, P. D.; Sittler, E. C.; Wesenberg, R. P.

2013-12-01

429

Estimation of wavelet and short-time Fourier transform sonograms of normal and diabetic subjects' electrogastrogram.  

PubMed

Electrogastrography (EGG) is a noninvasive way to record gastric electrical activity of stomach muscle by placing electrodes on the abdominal skin. Our goal was to investigate the frequency of abnormalities of the EGG in real clinical diabetic gastroparesis patients using WT method and to compare performance of STFT and WT methods in the case of time-frequency resolution. The results showed that WT sonograms can be used to classify patients successfully as healthy or sick. And also, due to the fact that the WT method does not suffer from some intrinsic problems that affect the STFT method, one can see that the WT method can help improve the quality of the sonogram of the EGG signals. PMID:16259973

Dirgenali, Fatma; Kara, Sadik; Okkesim, Sükrü

2006-12-01

430

Observation of Brownian motion in liquids at short times: instantaneous velocity and memory loss.  

PubMed

Measurement of the instantaneous velocity of Brownian motion of suspended particles in liquid probes the microscopic foundations of statistical mechanics in soft condensed matter. However, instantaneous velocity has eluded experimental observation for more than a century since Einstein's prediction of the small length and time scales involved. We report shot-noise-limited, high-bandwidth measurements of Brownian motion of micrometer-sized beads suspended in water and acetone by an optical tweezer. We observe the hydrodynamic instantaneous velocity of Brownian motion in a liquid, which follows a modified energy equipartition theorem that accounts for the kinetic energy of the fluid displaced by the moving bead. We also observe an anticorrelated thermal force, which is conventionally assumed to be uncorrelated. PMID:24675957

Kheifets, Simon; Simha, Akarsh; Melin, Kevin; Li, Tongcang; Raizen, Mark G

2014-03-28

431

Time-Resolved X-Ray Brightness Measurements from Short-Pulse, Laser-Irradiated Thin Foils  

NASA Astrophysics Data System (ADS)

The production of soft x rays (˜keV) from high-intensity, short-pulse laser plasmas is important for future applications such as backlighting cryogenic targets on OMEGA. The physics of short-pulse laser--plasma interactions and the coupling of laser energy into both the thermal plasma and fast electrons were studied to optimize x-ray production from mass-limited aluminum foil targets. Foil targets of various sizes from 50 to 500 ?m were irradiated with picosecond pulse duration laser pulses at intensities similar to OMEGA area backlighter schemes (10^18 to >10^19 W/cm^2). The time-resolved x-ray emission was measured with a conically curved crystal coupled with an ultrafast x-ray streak camera. The He? and the Ly? line emission from aluminum foils was spectrally measured and temporally resolved. In addition, the x-ray source was characterized with a calibrated time-integrated spectrograph and spatially resolved images were taken with a spherically curved Bragg crystal. The combination of these measurements allows the brilliance of the x-ray line source to be inferred. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

Eichman, B.; Theobald, W.; Stoeckl, C.; Mileham, C.; Sangster, T. C.

2012-10-01

432

Short-Term Chromospheric Variability in alpha Tauri (K5 III): Results from IUE Time Series Observations  

NASA Astrophysics Data System (ADS)

We evaluate time series observations of chromospheric lines (Mg II, Mg I, and C II) for the K giant ? Tau obtained using the IUE LWP camera at high dispersion. These observations cover a time span of about 2 weeks in 1994 February-March and were designed to resolve variations occurring within hours, days, and weeks. We consider the observational results in relation to theoretical acoustic heating models, motivated by the fact that ?Tau may exhibit a basal (i.e., minimum) level of chromospheric activity. The data reveal flux variations between the extremes of 8% in Mg II h + k and 15% in each emission component. These variations occur on timescales as short as 8 hr but not on timescales longer than ˜3 days. For the h and k components, flux variations occurring on a timescale as short as 1.5 hr are also found. These changes are often not correlated (and are sometimes even anticorrelated), leading to remarkable differences in the h/k ratios. We argue that these results are consistent with the presence of strong acoustic shocks, which can lead to variable Mg II line emission when only a small number of strong shocks are propagating through the atmosphere. We deduce the electron density in the C II] ?2325 line formation region to be log Ne ? 9.0, in agreement with previous studies. Our data provide evidence that the Mg II basal flux limit for K giants might be a factor of 4 higher than suggested by Rutten et al.

Cuntz, Manfred; Deeney, Bryan D.; Brown, Alexander; Stencel, Robert E.

1996-06-01

433

Copper (II) adsorption by the extracellular polymeric substance extracted from waste activated sludge after short-time aerobic digestion.  

PubMed

The extracellular polymeric substance (EPS) extracted from waste activated sludge (WAS) after short-time aerobic digestion was investigated to be used as a novel biosorbent for Cu(2+) removal from water. The EPS consisted of protein (52.6 %, w/w), polysaccharide (30.7 %, w/w), and nucleic acid (16.7 %, w/w). Short-time aerobic digestion process of WAS for about 4 h promoted the productivity growth of the EPS for about 10 %. With a molecular weight of about 1.9 × 10(6) Da, the EPS showed a linear structure with long chains, and contained carboxyl, hydroxyl, and amino groups. The sorption kinetics was well fit for the pseudo-second-order model, and the maximum sorption capacity of the EPS (700.3 mg Cu(2+)/g EPS) was markedly greater than those of the reported biosorbents. Both Langmuir model and Freundlich model commendably described the sorption isotherm. The Gibbs free energy analysis of the adsorption showed that the sorption process was feasible and spontaneous. According to the complex results of multiple analytical techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy, etc., the adsorption process took place via both physical and chemical sorption, but the electrostatic interaction between sorption sites with the functional groups and Cu(2+) is the major mechanism. PMID:24026202

Zhang, Zhiqiang; Zhou, Yun; Zhang, Jiao; Xia, Siqing

2014-02-01

434

Enzymatic hydrolysis of steam-exploded hardwood using short processing times.  

PubMed

Woody materials are generally resistant to enzymatic saccharification unless they undergo harsh fiber disrupting pre-treatments such as steam explosion. In this study, enzymatic hydrolysis of steam-exploded hardwood was investigated using various conditions and commercial cellulase preparations. Hydrolysis times were kept below 24 h in order to approach industrially realistic conditions. The optimal conditions for enzymatic hydrolysis were found to be 55 degrees C and a pH of about 4.5. During enzymatic hydrolysis, acetate was released from the hemicellulose fraction. Increasing the dry matter concentration had a negative effect on glucose yields. Using fermentors with pH control, 66% of the cellulose in steam-exploded hardwood could be hydrolyzed to glucose within 12 h using an enzyme dose of 25 filter paper units (FPU)/g of dry matter. For 24 h hydrolysis maximum cellulose saccharification (71%) was observed at 25 FPU/g, and increasing the enzyme dose further did not increase the sugar yield. PMID:20530898

Horn, Svein J; Eijsink, Vincent G H

2010-01-01

435

Flexible mate choice when mates are rare and time is short  

PubMed Central

Female mate choice is much more dynamic than we once thought. Mating decisions depend on both intrinsic and extrinsic factors, and these two may interact with one another. In this study, we investigate how responses to the social mating environment (extrinsic) change as individuals age (intrinsic). We first conducted a field survey to examine the extent of natural variation in mate availability in a population of threespine sticklebacks. We then manipulated the sex ratio in the laboratory to determine the impact of variation in mate availability on sexual signaling, competition, and mating decisions that are made throughout life. Field surveys revealed within season heterogeneity in mate availability across breeding sites, providing evidence for the variation necessary for the evolution of plastic preferences. In our laboratory study, males from both female-biased and male-biased treatments invested most in sexual signaling late in life, although they competed most early in life. Females became more responsive to courtship over time, and those experiencing female-biased, but not male-biased sex ratios, relaxed their mating decisions late in life. Our results suggest that social experience and age interact to affect sexual signaling and female mating decisions. Flexible behavior could mediate the potentially negative effects of environmental change on population viability, allowing reproductive success even when preferred mates are rare.

Tinghitella, Robin M; Weigel, Emily G; Head, Megan; Boughman, Janette W

2013-01-01

436

Assessment of transmission in trachoma programs over time suggests no short-term loss of immunity.  

PubMed

Trachoma programs have dramatically reduced the prevalence of the ocular chlamydia that cause the disease. Some have hypothesized that immunity to the infection may be reduced because of program success in reducing the incidence of infection, and transmission may then increase. Longitudinal studies of multiple communities would be necessary to test this hypothesis. Here, we quantify transmission using an estimated basic reproduction number based on 32 communities during the first, second, and third years of an antibiotic treatment program. We found that there is little to no increase in the basic reproduction number over time. The estimated linear trend in the basic reproduction number, [Formula: see text], was found to be -0.025 per year, 95% CI -0.167 to 0.117 per year. We are unable to find evidence supporting any loss of immunity over the course of a 3-year program. This is encouraging, as it allows the possibility that repeated mass antibiotic distributions may eliminate infection from even the most severely affected areas. PMID:23875038

Liu, Fengchen; Porco, Travis C; Ray, Kathryn J; Bailey, Robin L; Mkocha, Harran; Muñoz, Beatriz; Quinn, Thomas C; Lietman, Thomas M; West, Sheila K

2013-01-01

437

Exploiting few mode-fibers for optical time-stretch confocal microscopy in the short near-infrared window.  

PubMed

Dispersive fiber is well-regarded as the most viable candidate for realizing efficient optical time-stretch process--an ultrafast spectroscopic measurement technique based on the wavelength-to-time mapping via group velocity dispersion (GVD). Despite optical time-stretch has been anticipated to benefit a wide range of high-throughput biomedical diagnoses, the lack of commercially-available dispersive fibers which can operate in the "biomedically-favorable" short near-infrared (~800 nm - 1100 nm) range hinders practical time-stretch-based biomedical spectroscopy and microscopy. We here explore and demonstrate the feasibility of using the standard telecommunication single-mode fibers (e.g. SMF28 and dispersion compensation fiber (DCF)) as few-mode fibers (FMFs) for optical time-stretch confocal microscopy in the 1 ?m range. By evaluating GVD of different FMF modes and thus the corresponding time-stretch performances, we show that the fundamental modes (LP(01)) of SMF28 and DCF, having sufficiently high dispersion-to-loss ratios, are particularly useful for practical time-stretch spectroscopy and microscopy at 1 ?m, without the need for the specialty 1 ?m SMF. More intriguingly, we also show that the higher-order FMF modes (e.g. LP(11)) could be excited and utilized for time-stretch imaging. Such additional degree of freedom creates a new avenue for optimizing and designing the time-stretch operations, such as by tailored engineering of the modal-dispersion as well as the GVD of the individual FMF modes. PMID:23187174

Qiu, Yi; Xu, Jingjiang; Wong, Kenneth K Y; Tsia, Kevin K

2012-10-22

438

Temporal Dynamic Controllability Revisited  

NASA Technical Reports Server (NTRS)

An important issue for temporal planners is the ability to handle temporal uncertainty. We revisit the question of how to determine whether a given set of temporal requirements are feasible in the light of uncertain durations of some processes. In particular, we consider how best to determine whether a network is Dynamically Controllable, i.e., whether a dynamic strategy exists for executing the network that is guaranteed to satisfy the requirements. Previous work has shown the existence of a pseudo-polynomial algorithm for testing Dynamic Controllability. Here, we greatly simplify the previous framework, and present a true polynomial algorithm with a cutoff based only on the number of nodes.

Morris, Paul H.; Muscettola, Nicola

2005-01-01