Short-Time Nonlinear Effects in the Exciton-Polariton System

The P-wave spectra of seismograms from large underwater explosions are frequently dominated by reverberations. When this is so, a simple reverberation model similar to that of Backus (1959) gives a good approximation to the source spectrum. The basic wavelet determined by this method is not necessarily minimum‐delay. A few promising deconvolutions have been carried out, revealing a sequence of arrivals of comparable amplitudes separated by short time intervals. Synthetic seismograms which have been constructed from these spike sequences differ very little from the field records. However, the technique often yields output seismograms which are not easily interpreted. A study using synthetic seismograms suggests five reasons for this: 1) low signal‐to‐noise ratios, which result in too narrow a frequency band in which signal is predominant; 2) pulses arriving at the recorder having undergone phase changes during transmission, especially in combination with 3) very close spacing of the sequence of arrivals, causing overlap of the deconvolved output pulses; 4) the presence of arrivals which are not propagated along simple ray‐theory paths, and 5) poor estimation of the source parameters. Nonlinear effects and complex geology at the source are other possible causes of complications in the deconvolved records.

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Simple and efficient numerical tools for the analysis of parachutes

Engineering Computations ◽

10.1108/ec-10-2012-0247 ◽

2014 ◽

Vol 31 (5) ◽

pp. 957-985 ◽

Cited By ~ 3

Author(s):

Roberto Flores ◽

Enrique Ortega ◽

Eugenio Onate

Keyword(s):

Separated Flow ◽

Nonlinear Effects ◽

Computational Tools ◽

Content Type ◽

Explicit Finite Element ◽

Robust Solution ◽

Highly Nonlinear ◽

Unsteady Panel Method ◽

Numerical Tools ◽

Short Time

Purpose – The purpose of this paper is to describe a set of simple yet effective, numerical method for the design and evaluation of parachute-payload system. The developments include a coupled fluid-structural solver for unsteady simulations of ram-air type parachutes. The main features of the computational tools are described and several numerical examples are provided to illustrate the performance and capabilities of the technique. Design/methodology/approach – For an efficient solution of the aerodynamic problem, an unsteady panel method has been chosen exploiting the fact that large areas of separated flow are not expected under nominal flight conditions of ram-air parachutes. A dynamic explicit finite element solver is used for the structure. This approach yields a robust solution even when highly nonlinear effects due to large displacements and material response are present. The numerical results show considerable accuracy and robustness. Findings – A simple and effective numerical tool for the analysis of parachutes has been developed. Originality/value – An analysis code has been developed which addresses the needs of ram-air parachute designers. The software delivers reasonably accurate results in a short time using modest hardware. It can therefore assist the design process, which nowadays relies on empirical methods.

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Application of a Signal Technique to the Source–Receptor Relationship in Three-Dimensional Tracer Simulations

Journal of Applied Meteorology and Climatology ◽

10.1175/2010jamc2431.1 ◽

2010 ◽

Vol 49 (11) ◽

pp. 2197-2212

Author(s):

Zhan Zhao ◽

Shu-Hua Chen

Keyword(s):

Fourier Transform ◽

Three Dimensional ◽

Nonlinear Effects ◽

Atmospheric Model ◽

Frequency Space ◽

Study Results ◽

Pollutant Sources ◽

Pollutant Source ◽

The Fourier Transform ◽

Short Time

Abstract Identifying pollutant sources that contribute to downstream locations is important for policy making and air-quality control. In this study, a computationally economic signal technique was implemented into a three-dimensional nonhydrostatic atmospheric model to help to identify source–receptor relationships. An idealized supercell case and a semireal air-pollution case in Turkey were used to investigate the potential of the technique. For each pollutant, signals with various frequencies were emitted from different source locations and added into that particular type of emitted pollutants. The time series of pollutant concentration collected at receptors were then projected onto frequency space using the Fourier transform and short-time Fourier transform methods to identify the source locations. During the model integration, a particular tracer was also emitted from each pollutant source location (i.e., a conventional method to study the source–receptor relationship) to validate and evaluate the signal technique. Results show that frequencies could be slightly shifted after signals were transported for some distance and that evident secondary frequencies (i.e., beat frequencies) could be generated as a result of nonlinear effects. Although these could potentially confuse the identification of signals released from source points, signals were still distinguishable in this study. Results from a sensitivity test of the diffusion effect on different frequencies suggest that the effect of diffusion on amplitude damping is stronger for higher frequencies than for lower frequencies.

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What the replication reformation wrought

Behavioral and Brain Sciences ◽

10.1017/s0140525x18000857 ◽

2018 ◽

Vol 41 ◽

Cited By ~ 2

Author(s):

Barbara A. Spellman ◽

Daniel Kahneman

Keyword(s):

Reform Movement ◽

Short Time

AbstractReplication failures were among the triggers of a reform movement which, in a very short time, has been enormously useful in raising standards and improving methods. As a result, the massive multilab multi-experiment replication projects have served their purpose and will die out. We describe other types of replications – both friendly and adversarial – that should continue to be beneficial.

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Periodic Variations in the Coronal Green Line Intensity and their Connection with the White-light Coronal Structures

International Astronomical Union Colloquium ◽

10.1017/s0252921100064484 ◽

2000 ◽

Vol 179 ◽

pp. 197-200

Author(s):

Milan Minarovjech ◽

Milan Rybanský ◽

Vojtech Rušin

Keyword(s):

Time Resolution ◽

White Light ◽

Short Time Scale ◽

High Time Resolution ◽

Green Line ◽

Periodic Intensity ◽

Coronal Green Line ◽

Significant Intensity ◽

Short Time ◽

Coronal Structures

AbstractWe present an analysis of short time-scale intensity variations in the coronal green line as obtained with high time resolution observations. The observed data can be divided into two groups. The first one shows periodic intensity variations with a period of 5 min. the second one does not show any significant intensity variations. We studied the relation between regions of coronal intensity oscillations and the shape of white-light coronal structures. We found that the coronal green-line oscillations occur mainly in regions where open white-light coronal structures are located.

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Destruction of Actin Filaments by Osmium Tetroxide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079772 ◽

1977 ◽

Vol 35 ◽

pp. 466-467

Author(s):

P. Maupin-Szamier ◽

T. D. Pollard

Keyword(s):

Actin Filaments ◽

Time Course ◽

Osmium Tetroxide ◽

Rabbit Muscle ◽

Muscle Actin ◽

Sodium Phosphate Buffer ◽

Transmission Electron ◽

The Difference ◽

Rates Of Decay ◽

Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

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Effect of a Complex Heat Treatment on the Structure of 300M Steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098071 ◽

1981 ◽

Vol 39 ◽

pp. 312-313

Author(s):

R. Padmanabhan ◽

W. E. Wood

Keyword(s):

Heat Treatment ◽

Metal Carbides ◽

Austenite Grain Size ◽

300M Steel ◽

Heat Treated ◽

Strain Fracture ◽

Prior Austenite Grain Size ◽

Short Time ◽

Final Tempering ◽

Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

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Transmission Electron Microscopy of an Aluminum-Silver-Stainless Steel Solid State Bond

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117832 ◽

1985 ◽

Vol 43 ◽

pp. 172-173

Author(s):

M. J. Carr ◽

J. F. Shewbridge ◽

T. O. Wilford

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Solid State ◽

Specimen Preparation ◽

Dimensional Control ◽

Tem Analysis ◽

Metal Parts ◽

Dissimilar Metal ◽

Transmission Electron ◽

Short Time

Strong solid state bonds are routinely produced between physical vapor deposited (PVD) silver coatings deposited on sputter cleaned surfaces of two dissimilar metal parts. The low temperature (200°C) and short time (10 min) used in the bonding cycle are advantageous from the standpoint of productivity and dimensional control. These conditions unfortunately produce no microstructural changes at or near the interface that are detectable by optical, SEM, or microprobe examination. Microstructural problems arising at these interfaces could therefore easily go undetected by these techniques. TEM analysis has not been previously applied to this problem because of the difficulty in specimen preparation. The purpose of this paper is to describe our technique for preparing specimens from solid state bonds and to present our initial observations of the microstructural details of such bonds.

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Electronmicroscopic localization of ribonucleic acids in ciliate Bursaria truncatella during cell division

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158200 ◽

1990 ◽

Vol 48 (3) ◽

pp. 132-133

Author(s):

Vladimir Popenko ◽

Natalya Cherny ◽

Maria Yakovleva

Keyword(s):

Cell Division ◽

High Specificity ◽

Longitudinal Axis ◽

Gold Complexes ◽

Somatic Nucleus ◽

Ribonucleic Acids ◽

Biological Meaning ◽

Bivalent Cations ◽

Lowicryl K4m ◽

Short Time

Highly polyploid somatic nucleus (macronucleus) of ciliate Bursaria truncatella under goes severe changes in morphology during cell division. At first, macronucleus (Ma) condences, diminishes in size and turns perpendicular to longitudinal axis of the cell. After short time, Ma turns again, elongates and only afterwards the process of division itself occurs. The biological meaning of these phenomena is not clear.Localization of RNA in the cells was performed on sections of ciliates B. truncatella, embedded in “Lowicryl K4M” at various stages: (1) before cell division (Figs. 2,3); (11) at the stage of macronucleus condensation; (111) during elongation of Ma (Fig.4); (1111) in young cells (0-5min. after division). For cytochemical labelling we used RNaseAcolloidal gold complexes (RNase-Au), which are known to bind to RNA containing cell ularstructures with high specificity. The influence of different parameters on the reliability and reproducibility of labelling was studied. In addition to the factors, discussed elsewhere, we found that the balance of mono- and bivalent cations is of great significance.

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Perioperative Steroids: Use Low Dose for a Short Time

Hospitalist News ◽

10.1016/s1875-9122(08)70174-3 ◽

2008 ◽

Vol 1 (7) ◽

pp. 10

Author(s):

KERRI WACHTER

Keyword(s):

Low Dose ◽

Short Time

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