Bulk stress auto-correlation function in simple liquids-sum rules

International Nuclear Information System (INIS)

Tankeshwar, K.; Bhandari, R.; Pathak, K.N.

1990-10-01

Expressions for the zeroth, second and fourth frequency sum rules of the bulk stress auto correlation function have been derived. The exact expressions involve static correlation function up to four particles. Because of the non availability of any information about static quadruplet correlation function we use a low order decoupling approximation for this. In this work, we have obtained, separately, the sum rules for the different mechanism of momentum transfer in the fluids. The results are expected to be useful in the study of bulk viscosity of the fluids. (author). 9 refs

Transfer function analysis of radiographic imaging systems

International Nuclear Information System (INIS)

Metz, C.E.; Doi, K.

1979-01-01

The theoretical and experimental aspects of the techniques of transfer function analysis used in radiographic imaging systems are reviewed. The mathematical principles of transfer function analysis are developed for linear, shift-invariant imaging systems, for the relation between object and image and for the image due to a sinusoidal plane wave object. The other basic mathematical principle discussed is 'Fourier analysis' and its application to an input function. Other aspects of transfer function analysis included are alternative expressions for the 'optical transfer function' of imaging systems and expressions are derived for both serial and parallel transfer image sub-systems. The applications of transfer function analysis to radiographic imaging systems are discussed in relation to the linearisation of the radiographic imaging system, the object, the geometrical unsharpness, the screen-film system unsharpness, other unsharpness effects and finally noise analysis. It is concluded that extensive theoretical, computer simulation and experimental studies have demonstrated that the techniques of transfer function analysis provide an accurate and reliable means for predicting and understanding the effects of various radiographic imaging system components in most practical diagnostic medical imaging situations. (U.K.)

Experimental measurement of zero power reactor transfer function

International Nuclear Information System (INIS)

Liang Shuhong

2011-01-01

In order to study the zero power reactor (ZPR) transfer function, the ZPR transfer function expression was deduced with the point reactor kinetics equation, which was disturbed by reactivity input response. Based on the Fourier analysis for the input of triangular wave, the relation between the transfer function and reactivity was got. Validating research experiment was made on the DF-VI fast ZPR. After the disturbed reactivity was measured, the experimental value of the transfer function was got. According to the experimental value and the calculated value, the expression of the ZPR transfer function is proved, whereas the disturbed reactivity is got from the transfer function. (authors)

Experimental study of interfacial shear stress for an analogy model of evaporative heat transfer

International Nuclear Information System (INIS)

Kwon, Hyuk; Park, GoonCherl; Min, ByungJoo

2008-01-01

In this study, we conducted measurements of an evaporative interfacial shear stress in a passive containment cooling system (PCCS). An interfacial shear stress for a counter-current flow was measured from a momentum balance equation and the interfacial friction factor for evaporation was evaluated by using experimental data. A model for the evaporative heat transfer coefficient of a vertical evaporative flat surface was developed based on an analogy between heat and momentum transfer. It was found that the interfacial shear stress increases with the Jacob number, which incorporates the evaporation rate, and the air and water Reynolds numbers. The relationship between the evaporative heat transfer and the interfacial shear stress was evaluated by using the experimental results. This relationship was used to develop a model for an evaporative heat transfer coefficient by using an analogy between heat and mass transfer. The prediction of this model were found to be in good agreement with the experimental data obtained for evaporative heat transfer by Kang and Park. (author)

Stress transfer mechanisms at the submicron level for graphene/polymer systems.

Science.gov (United States)

Anagnostopoulos, George; Androulidakis, Charalampos; Koukaras, Emmanuel N; Tsoukleri, Georgia; Polyzos, Ioannis; Parthenios, John; Papagelis, Konstantinos; Galiotis, Costas

2015-02-25

The stress transfer mechanism from a polymer substrate to a nanoinclusion, such as a graphene flake, is of extreme interest for the production of effective nanocomposites. Previous work conducted mainly at the micron scale has shown that the intrinsic mechanism of stress transfer is shear at the interface. However, since the interfacial shear takes its maximum value at the very edge of the nanoinclusion it is of extreme interest to assess the effect of edge integrity upon axial stress transfer at the submicron scale. Here, we conduct a detailed Raman line mapping near the edges of a monolayer graphene flake that is simply supported onto an epoxy-based photoresist (SU8)/poly(methyl methacrylate) matrix at steps as small as 100 nm. We show for the first time that the distribution of axial strain (stress) along the flake deviates somewhat from the classical shear-lag prediction for a region of ∼ 2 μm from the edge. This behavior is mainly attributed to the presence of residual stresses, unintentional doping, and/or edge effects (deviation from the equilibrium values of bond lengths and angles, as well as different edge chiralities). By considering a simple balance of shear-to-normal stresses at the interface we are able to directly convert the strain (stress) gradient to values of interfacial shear stress for all the applied tensile levels without assuming classical shear-lag behavior. For large flakes a maximum value of interfacial shear stress of 0.4 MPa is obtained prior to flake slipping.

Multichannel transfer function with dimensionality reduction

KAUST Repository

Kim, Han Suk; Schulze, Jü rgen P.; Cone, Angela C.; Sosinsky, Gina E.; Martone, Maryann E.

2010-01-01

. Our new method provides a framework to combine multiple approaches and pushes the boundary of gradient-based transfer functions to multiple channels, while still keeping the dimensionality of transfer functions to a manageable level, i.e., a maximum

Fault detection using parameter transfer functions

Energy Technology Data Exchange (ETDEWEB)

Salamun, I; Mavko, B; Stritar, A [University of Ljubljana, Josef Stefan Inst., Ljubljana (Slovenia). Reactor Engineering Div.

1997-12-31

To reduce the number of alarms in NPP many techniques have been proposed for process monitoring and diagnosis. The object of our investigation is a dynamic process with digital signals. The general parametric model defines the transfer function form and it covers all dynamics characteristics between two monitoring parameters. To determine the proper model coefficients we are using recoursing least square methods. The transfer function coefficients define the correlation between two variables in desired time period. During process monitoring just the relation is observed because the number of coefficients and the structure is predefined with transfer function form. During plant operation the transfer functions for important parameters must be calculated and estimated. The estimated values are input parameters for an analytical algorithm. It determines which part of system causes the transient and recognizes it. The proposed methodology allows a computer to monitor the system behaviour and to find out the most probable cause for abnormal condition. (author). 3 refs, 5 figs, 2 tabs.

Fault detection using parameter transfer functions

International Nuclear Information System (INIS)

Salamun, I.; Mavko, B.; Stritar, A.

1996-01-01

To reduce the number of alarms in NPP many techniques have been proposed for process monitoring and diagnosis. The object of our investigation is a dynamic process with digital signals. The general parametric model defines the transfer function form and it covers all dynamics characteristics between two monitoring parameters. To determine the proper model coefficients we are using recoursing least square methods. The transfer function coefficients define the correlation between two variables in desired time period. During process monitoring just the relation is observed because the number of coefficients and the structure is predefined with transfer function form. During plant operation the transfer functions for important parameters must be calculated and estimated. The estimated values are input parameters for an analytical algorithm. It determines which part of system causes the transient and recognizes it. The proposed methodology allows a computer to monitor the system behaviour and to find out the most probable cause for abnormal condition. (author). 3 refs, 5 figs, 2 tabs

Characterization of functional SSR markers in Prosopis alba and their transferability across Prosopis species

OpenAIRE

María F. Pomponio; Cintia Acuña; Vivien Pentreath; Diego L. Lauenstein; Susana M. Poltri; Susana Torales

2015-01-01

Aim of study: The aim of the study was to characterize functional microsatellite markers in Prosopis alba and examine the transferability to species from the Prosopis genus. Area of the study: samples were obtained from natural populations of Argentina. Material and Methods: Eleven SSR functional markers related to stress and metabolism were amplified in a sample of 152 genotypes from P.alba, P. denudans, P. hassleriP. chilensis, P. flexuosa, and interspecific hybrids. Main res...

Automatic computation of transfer functions

Science.gov (United States)

Atcitty, Stanley; Watson, Luke Dale

2015-04-14

Technologies pertaining to the automatic computation of transfer functions for a physical system are described herein. The physical system is one of an electrical system, a mechanical system, an electromechanical system, an electrochemical system, or an electromagnetic system. A netlist in the form of a matrix comprises data that is indicative of elements in the physical system, values for the elements in the physical system, and structure of the physical system. Transfer functions for the physical system are computed based upon the netlist.

Development of a UF{sub 6} cylinder transient heat transfer/stress analysis model

Energy Technology Data Exchange (ETDEWEB)

Williams, W.R. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)

1991-12-31

A heat transfer/stress analysis model is being developed to simulate the heating to a point of rupture of a cylinder containing UF{sub 6} when it is exposed to a fire. The assumptions underlying the heat transfer portion of the model, which has been the focus of work to date, will be discussed. A key aspect of this model is a lumped parameter approach to modeling heat transfer. Preliminary results and future efforts to develop an integrated thermal/stress model will be outlined.

Examining the role of Coulomb static stress transfer in injection-induced seismicity: a generic modeling approach

Science.gov (United States)

Brown, M. R. M.; Ge, S.

2017-12-01

Increased pore pressure decreasing the effective stress on a critically stressed fault has been the accepted mechanism for injection-induced seismicity. This, however, is an over simplified approach that does not take into account the coupled hydro-mechanical effects. In addition, this approach leaves out a possible key stressor in the system, the earthquakes. Earthquakes are known to interact with each other by Coulomb static stress transfer, the process of permanent stress change caused by movement on a fault. In areas of induced seismicity, many small to moderate earthquakes can occur adding to the stress in the system via Coulomb static stress transfer. Here we ask: Is the Coulomb static stress transfer from the earthquakes as important as the pore pressure increase or stress changes caused by coupled hydro-mechanical processes? Is there a point where the Coulomb static stress transfer from the earthquakes becomes the controlling process for inducing future earthquakes? How does the effect of many small earthquakes compare to a few larger events in terms of Coulomb static stress transfer? In this study, we use hydrologic and coupled hydro-mechanical models and USGS Coulomb 3 to assess the importance of induced earthquakes in terms of the stress change in the system. Realistic scenarios of wastewater injection and earthquake magnitude-frequency distributions are used to develop generic models. Model variables and data are varied to evaluate the range of possible outcomes. Preliminary results show that the stress change associated with injection is of the same order of magnitude as the cumulative Coulomb static stress change of a series of small (1

Static stress transfer during the 2002 Nenana Mountain-Denali Fault, Alaska, earthquake sequence

Science.gov (United States)

Anderson, G.; Ji, C.

2003-01-01

On 23 October 2002, the Mw 6.7 Nenana Mountain earthquake occurred in central Alaska. It was followed on 3 November 2002 by the Mw 7.9 Denali Fault mainshock, the largest strike-slip earthquake to occur in North America during the past 150 years. We have modeled static Coulomb stress transfer effects during this sequence. We find that the Nenana Mountain foreshock transferred 30-50 kPa of Coulomb stress to the hypocentral region of the Denali Fault mainshock, encouraging its occurrence. We also find that the two main earthquakes together transferred more than 400 kPa of Coulomb stress to the Cross Creek segment of the Totschunda fault system and to the Denali fault southeast of the mainshock rupture, and up to 80 kPa to the Denali fault west of the Nenana Mountain rupture. Other major faults in the region experienced much smaller static Coulomb stress changes.

Coulomb stress transfer and tectonic loading preceding the 2002 Denali fault earthquake

Science.gov (United States)

Bufe, Charles G.

2006-01-01

Pre-2002 tectonic loading and Coulomb stress transfer are modeled along the rupture zone of the M 7.9 Denali fault earthquake (DFE) and on adjacent segments of the right-lateral Denali–Totschunda fault system in central Alaska, using a three-dimensional boundary-element program. The segments modeled closely follow, for about 95°, the arc of a circle of radius 375 km centered on an inferred asperity near the northeastern end of the intersection of the Patton Bay fault with the Alaskan megathrust under Prince William Sound. The loading model includes slip of 6 mm/yr below 12 km along the fault system, consistent with rotation of the Wrangell block about the asperity at a rate of about 1°/m.y. as well as slip of the Pacific plate at 5 cm/yr at depth along the Fairweather–Queen Charlotte transform fault system and on the Alaska megathrust. The model is consistent with most available pre-2002 Global Positioning System (GPS) displacement rate data. Coulomb stresses induced on the Denali–Totschunda fault system (locked above 12 km) by slip at depth and by transfer from the M 9.2 Prince William Sound earthquake of 1964 dominated the changing Coulomb stress distribution along the fault. The combination of loading (∼70–85%) and coseismic stress transfer from the great 1964 earthquake (∼15–30%) were the principal post-1900 stress factors building toward strike-slip failure of the northern Denali and Totschunda segments in the M 7.9 earthquake of November 2002. Postseismic stresses transferred from the 1964 earthquake may also have been a significant factor. The M 7.2–7.4 Delta River earthquake of 1912 (Carver et al., 2004) may have delayed or advanced the timing of the DFE, depending on the details and location of its rupture. The initial subevent of the 2002 DFE earthquake was on the 40-km Susitna Glacier thrust fault at the western end of the Denali fault rupture. The Coulomb stress transferred from the 1964 earthquake moved the Susitna Glacier thrust

General post-Minkowskian expansion of time transfer functions

Energy Technology Data Exchange (ETDEWEB)

Teyssandier, Pierre; Poncin-Lafitte, Christophe Le [Departement Systemes de Reference Temps et Espace, CNRS/UMR 8630, Observatoire de Paris, 61 avenue de l' Observatoire, F-75014 Paris (France)

2008-07-21

Modeling most of the tests of general relativity requires us to know the function relating light travel time to the coordinate time of reception and to the spatial coordinates of the emitter and the receiver. We call such a function the reception time transfer function. Of course, an emission time transfer function may as well be considered. We present here a recursive procedure enabling us to expand each time transfer function into a perturbative series of ascending powers of the Newtonian gravitational constant G (general post-Minkowskian expansion). Our method is self-sufficient in the sense that neither the integration of null geodesic equations nor the determination of Synge's world function is necessary. To illustrate the method, the time transfer function of a three-parameter family of static, spherically symmetric metrics is derived within the post-linear approximation.

General post-Minkowskian expansion of time transfer functions

International Nuclear Information System (INIS)

Teyssandier, Pierre; Poncin-Lafitte, Christophe Le

2008-01-01

Modeling most of the tests of general relativity requires us to know the function relating light travel time to the coordinate time of reception and to the spatial coordinates of the emitter and the receiver. We call such a function the reception time transfer function. Of course, an emission time transfer function may as well be considered. We present here a recursive procedure enabling us to expand each time transfer function into a perturbative series of ascending powers of the Newtonian gravitational constant G (general post-Minkowskian expansion). Our method is self-sufficient in the sense that neither the integration of null geodesic equations nor the determination of Synge's world function is necessary. To illustrate the method, the time transfer function of a three-parameter family of static, spherically symmetric metrics is derived within the post-linear approximation

An in situ Raman spectroscopy study of stress transfer between carbon nanotubes and polymer

International Nuclear Information System (INIS)

Mu Minfang; Winey, Karen I; Osswald, Sebastian; Gogotsi, Yury

2009-01-01

The transfer mechanism of applied stress in single-wall carbon nanotube (SWCNT)/poly(methyl methacrylate) (PMMA) nanocomposites was investigated using in situ Raman spectroscopy on composite fibers. These SWCNT/PMMA nanocomposite fibers have no specific SWCNT-polymer interactions and the high degree of nanotube alignment minimizes the contributions from nanotube-nanotube interactions. Although tensile testing found significantly improved overall mechanical properties of the fibers, effective stress transfer to SWCNTs is limited to a small strain regime (ε<0.2%). At higher strains, the stress on the SWCNTs decreases due to the slippage at the nanotube-polymer interface. Slippage was also evident in scanning electron micrographs of fracture surfaces produced by tensile testing of the composite fibers. Above ε = 0.2%, the strain-induced slippage was accompanied by irreversible responses in stress and Raman peak shifts. This paper shows that efficient stress transfer to nanotubes as monitored by Raman spectroscopy is crucial to improving the mechanical properties of polymer nanocomposites and to detecting internal damage in nanocomposites.

Fault-patch stress-transfer efficiency in presence of sub-patch geometric complexity

KAUST Repository

Zielke, Olaf

2015-04-01

It is well known that faults are not planar surfaces. Instead they exhibit self-similar or self-affine properties that span a wide range of spatial (sub-micrometer to tens-of-kilometer). This geometric fault roughness has a distinct impact on amount and distribution of stresses/strains induced in the medium and on other portions of the fault. However, when numerically simulated (for example in multi-cycle EQ rupture simulations or Coulomb failure stress calculations) this roughness is largely ignored: individual fault patches --the incremental elements that build the fault surface in the respective computer models-- are planar and fault roughness at this and lower spatial scales is not considered. As a result, the fault-patch stress-transfer efficiency may be systematically too large in those numerical simulations with respect to the "actual" efficiency level. Here, we investigate the effect of sub-patch geometric complexity on fault-patch stress-transfer efficiency. For that, we sub-divide a fault patch (e.g., 1x1km) into a large number of sub-patches (e.g., 20x20m) and determine amount of induced stresses at selected positions around that patch for different levels and realizations of fault roughness. For each fault roughness level, we compute mean and standard deviation of the induced stresses, enabling us to compute the coefficient of variation. We normalize those values with stresses from the corresponding single (planar) fault patch, providing scaling factors and their variability for stress transfer efficiency. Given a certain fault roughness that is assumed for a fault, this work provides the means to implement the sub-patch fault roughness into investigations based on fault-patch interaction schemes.

Modulation transfer function cascade model for a sampled IR imaging system.

Science.gov (United States)

de Luca, L; Cardone, G

1991-05-01

The performance of the infrared scanning radiometer (IRSR) is strongly stressed in convective heat transfer applications where high spatial frequencies in the signal that describes the thermal image are present. The need to characterize more deeply the system spatial resolution has led to the formulation of a cascade model for the evaluation of the actual modulation transfer function of a sampled IR imaging system. The model can yield both the aliasing band and the averaged modulation response for a general sampling subsystem. For a line scan imaging system, which is the case of a typical IRSR, a rule of thumb that states whether the combined sampling-imaging system is either imaging-dependent or sampling-dependent is proposed. The model is tested by comparing it with other noncascade models as well as by ad hoc measurements performed on a commercial digitized IRSR.

Functional check of telescoping transfer pumps

International Nuclear Information System (INIS)

Sharpe, C.L.

1994-01-01

Activities are defined which constitute a functional check of a telescoping transfer pump (TTP). This report is written to the Procedures group of HLW and particularly applies to those TTP's which are the sole means of emergency transfer from a HLW waste tank

Transferability between Hospitals of Hypercalcaemia Discriminant Functions

DEFF Research Database (Denmark)

Frølich, Anne; McNair, Peter; Nielsen, Bo Friis

1996-01-01

Transferability of discriminant functions is potentially useful both from an economical point of view and because, in general, medical knowledge, in this case discriminant functions, should be transferable. In the present study we have evaluated the transferability of discriminant functions......, estimated from routine laboratory analysis, age and sex in two consecutively recorded populations with hypercalcemia including 162 and 257 patients with hypercalcemia. Discriminant functions were developed for each sex to distinguish between hypercalcemia associated with malignancy and hypercalcemia...... associated with other medical diseases. The total diagnostic accuracy in Herlev was 82 and 78%, in women and men, and increased to 87 and 86% in both sexes considering cases classified with posterior probability levels of 60%. In Hvidovre the total diagnostic accuracy was 81 and 84% in women and men...

Stress transfer in microdroplet tensile test: PVC-coated and uncoated Kevlar-29 single fiber

Science.gov (United States)

Zhenkun, Lei; Quan, Wang; Yilan, Kang; Wei, Qiu; Xuemin, Pan

2010-11-01

The single fiber/microdroplet tensile test is applied for evaluating the interfacial mechanics between a fiber and a resin substrate. It is used to investigate the influence of a polymer coating on a Kevlar-29 fiber surface, specifically the stress transfer between the fiber and epoxy resin in a microdroplet. Unlike usual tests, this new test ensures a symmetrical axial stress on the embedded fiber and reduces the stress singularity that appears at the embedded fiber entry. Using a homemade loading device, symmetrical tensile tests are performed on a Kevlar-29 fiber with or without polyvinylchloride (PVC) coating, the surface of which is in contact with two epoxy resin microdroplets during curing. Raman spectra on the embedded fiber are recorded by micro-Raman Spectroscopy under different strain levels. Then they are transformed to the distributions of fiber axis stress based on the relationship between stress and Raman shift. The Raman results reveal that the fiber axial stresses increase with the applied loads, and the antisymmetric interfacial shear stresses, obtained by a straightforward balance of shear-to-axial forces argument, lead to the appearance of shear stress concentrations at a distance to the embedded fiber entry. The load is transferred from the outer fiber to the embedded fiber in the epoxy microdroplet. As is observed by scanning electronic microscopy (SEM), the existence of a flexible polymer coating on the fiber surface reduces the stress transfer efficiency.

Game theoretic aspect of production process transfer functions ...

African Journals Online (AJOL)

Game theoretic aspect of production process transfer functions. ... On the final analysis, it was shown that relating transfer function to Bayesian games and mechanism design would lead to optimal bids, optimal ... AJOL African Journals Online.

Physical and virtual water transfers for regional water stress alleviation in China.

Science.gov (United States)

Zhao, Xu; Liu, Junguo; Liu, Qingying; Tillotson, Martin R; Guan, Dabo; Hubacek, Klaus

2015-01-27

Water can be redistributed through, in physical terms, water transfer projects and virtually, embodied water for the production of traded products. Here, we explore whether such water redistributions can help mitigate water stress in China. This study, for the first time to our knowledge, both compiles a full inventory for physical water transfers at a provincial level and maps virtual water flows between Chinese provinces in 2007 and 2030. Our results show that, at the national level, physical water flows because of the major water transfer projects amounted to 4.5% of national water supply, whereas virtual water flows accounted for 35% (varies between 11% and 65% at the provincial level) in 2007. Furthermore, our analysis shows that both physical and virtual water flows do not play a major role in mitigating water stress in the water-receiving regions but exacerbate water stress for the water-exporting regions of China. Future water stress in the main water-exporting provinces is likely to increase further based on our analysis of the historical trajectory of the major governing socioeconomic and technical factors and the full implementation of policy initiatives relating to water use and economic development. Improving water use efficiency is key to mitigating water stress, but the efficiency gains will be largely offset by the water demand increase caused by continued economic development. We conclude that much greater attention needs to be paid to water demand management rather than the current focus on supply-oriented management.

Improved Wave-vessel Transfer Functions by Uncertainty Modelling

DEFF Research Database (Denmark)

Nielsen, Ulrik Dam; Fønss Bach, Kasper; Iseki, Toshio

2016-01-01

This paper deals with uncertainty modelling of wave-vessel transfer functions used to calculate or predict wave-induced responses of a ship in a seaway. Although transfer functions, in theory, can be calculated to exactly reflect the behaviour of the ship when exposed to waves, uncertainty in inp...

Time-variable stress transfer across a megathrust from seismic to Wilson cycle scale

Science.gov (United States)

Rosenau, Matthias; Angiboust, Samuel; Moreno, Marcos; Schurr, Bernd; Oncken, Onno

2013-04-01

During the lifetime of a convergent plate margin stress transfer across the plate interface (a megathrust) can be expected to vary at multiple timescales. At short time scales (years to decades), a subduction megathrust interface appears coupled (accumulating shear stress) at shallow depth (seismogenic zone proportional to effective normal load but also to relative shear stress. For areas of near complete stress drop locking might systematically decrease over the interseismic period from >80-95 % shortly after an earthquake to backslip at significant fractions of plate convergence rate (non-volcanic tremor and slow slip below the seismogenic zone represent short term episodes of metamorphic fluid infiltration into the shallow megathrust. A megathrust fault valve mechanism clocked by the greatest earthquakes then accounts for cyclic fluid pressure build up and drainage at sub-seismic cycle scale. As pore pressure dynamics are controlled primarily by permeability which in turn is controlled by structure and material properties, then more long term coupling transients associated with structural evolution of the plate margin can be implied. Fluid controlled transients might interfere with transients and secular trends resulting from changes in material strength and plate tectonic forces over the Wilson cycle resulting in a multispectral stress-transfer pattern associated with convergent margin evolution. Because of the viscous damping effect of the underlying asthenosphere, however, only longterm transients (periods >1-10 ka) are transmitted into the engaged plates. We therefore speculate that the multispectral nature of stress transfer across a megathrust filtered through the asthenosphere explains transient fault activity in some intraplate settings.

Consistent Parameter and Transfer Function Estimation using Context Free Grammars

Science.gov (United States)

Klotz, Daniel; Herrnegger, Mathew; Schulz, Karsten

2017-04-01

This contribution presents a method for the inference of transfer functions for rainfall-runoff models. Here, transfer functions are defined as parametrized (functional) relationships between a set of spatial predictors (e.g. elevation, slope or soil texture) and model parameters. They are ultimately used for estimation of consistent, spatially distributed model parameters from a limited amount of lumped global parameters. Additionally, they provide a straightforward method for parameter extrapolation from one set of basins to another and can even be used to derive parameterizations for multi-scale models [see: Samaniego et al., 2010]. Yet, currently an actual knowledge of the transfer functions is often implicitly assumed. As a matter of fact, for most cases these hypothesized transfer functions can rarely be measured and often remain unknown. Therefore, this contribution presents a general method for the concurrent estimation of the structure of transfer functions and their respective (global) parameters. Note, that by consequence an estimation of the distributed parameters of the rainfall-runoff model is also undertaken. The method combines two steps to achieve this. The first generates different possible transfer functions. The second then estimates the respective global transfer function parameters. The structural estimation of the transfer functions is based on the context free grammar concept. Chomsky first introduced context free grammars in linguistics [Chomsky, 1956]. Since then, they have been widely applied in computer science. But, to the knowledge of the authors, they have so far not been used in hydrology. Therefore, the contribution gives an introduction to context free grammars and shows how they can be constructed and used for the structural inference of transfer functions. This is enabled by new methods from evolutionary computation, such as grammatical evolution [O'Neill, 2001], which make it possible to exploit the constructed grammar as a

Transfer Function Control for Biometric Monitoring System

Science.gov (United States)

Chmiel, Alan J. (Inventor); Humphreys, Bradley T. (Inventor); Grodinsky, Carlos M. (Inventor)

2015-01-01

A modular apparatus for acquiring biometric data may include circuitry operative to receive an input signal indicative of a biometric condition, the circuitry being configured to process the input signal according to a transfer function thereof and to provide a corresponding processed input signal. A controller is configured to provide at least one control signal to the circuitry to programmatically modify the transfer function of the modular system to facilitate acquisition of the biometric data.

Filtering Non-Linear Transfer Functions on Surfaces.

Science.gov (United States)

Heitz, Eric; Nowrouzezahrai, Derek; Poulin, Pierre; Neyret, Fabrice

2014-07-01

Applying non-linear transfer functions and look-up tables to procedural functions (such as noise), surface attributes, or even surface geometry are common strategies used to enhance visual detail. Their simplicity and ability to mimic a wide range of realistic appearances have led to their adoption in many rendering problems. As with any textured or geometric detail, proper filtering is needed to reduce aliasing when viewed across a range of distances, but accurate and efficient transfer function filtering remains an open problem for several reasons: transfer functions are complex and non-linear, especially when mapped through procedural noise and/or geometry-dependent functions, and the effects of perspective and masking further complicate the filtering over a pixel's footprint. We accurately solve this problem by computing and sampling from specialized filtering distributions on the fly, yielding very fast performance. We investigate the case where the transfer function to filter is a color map applied to (macroscale) surface textures (like noise), as well as color maps applied according to (microscale) geometric details. We introduce a novel representation of a (potentially modulated) color map's distribution over pixel footprints using Gaussian statistics and, in the more complex case of high-resolution color mapped microsurface details, our filtering is view- and light-dependent, and capable of correctly handling masking and occlusion effects. Our approach can be generalized to filter other physical-based rendering quantities. We propose an application to shading with irradiance environment maps over large terrains. Our framework is also compatible with the case of transfer functions used to warp surface geometry, as long as the transformations can be represented with Gaussian statistics, leading to proper view- and light-dependent filtering results. Our results match ground truth and our solution is well suited to real-time applications, requires only a few

DISTRIBUTED RC NETWORKS WITH RATIONAL TRANSFER FUNCTIONS,

Science.gov (United States)

A distributed RC circuit analogous to a continuously tapped transmission line can be made to have a rational short-circuit transfer admittance and...one rational shortcircuit driving-point admittance. A subcircuit of the same structure has a rational open circuit transfer impedance and one rational ...open circuit driving-point impedance. Hence, rational transfer functions may be obtained while considering either generator impedance or load

Determination of the transfer function of a reactor

International Nuclear Information System (INIS)

Dencs, B.

1976-01-01

The theoretical and experimental methods of the determination of reactor transfer functions are reviewed. Preliminary measurements were made on the experimental and final core of the training reactor of the Budapest Technical University. The rod-drop curves, the hole effect of the reactor and the control rod worths were determined. The effect of Cd ring and Cd profile was studied, too. The neutron flux distribution in the core was determined in several geometries. The oscillatory method is treated in detail. After the zero measurements of the core the oscillatory determination of the transfer function has been made on some frequency. The simplified model of the reactor transfer function was reconstructed from the measurement data. (R.J.)

Stress field models from Maxwell stress functions: southern California

Science.gov (United States)

Bird, Peter

2017-08-01

The lithospheric stress field is formally divided into three components: a standard pressure which is a function of elevation (only), a topographic stress anomaly (3-D tensor field) and a tectonic stress anomaly (3-D tensor field). The boundary between topographic and tectonic stress anomalies is somewhat arbitrary, and here is based on the modeling tools available. The topographic stress anomaly is computed by numerical convolution of density anomalies with three tensor Green's functions provided by Boussinesq, Cerruti and Mindlin. By assuming either a seismically estimated or isostatic Moho depth, and by using Poisson ratio of either 0.25 or 0.5, I obtain four alternative topographic stress models. The tectonic stress field, which satisfies the homogeneous quasi-static momentum equation, is obtained from particular second derivatives of Maxwell vector potential fields which are weighted sums of basis functions representing constant tectonic stress components, linearly varying tectonic stress components and tectonic stress components that vary harmonically in one, two and three dimensions. Boundary conditions include zero traction due to tectonic stress anomaly at sea level, and zero traction due to the total stress anomaly on model boundaries at depths within the asthenosphere. The total stress anomaly is fit by least squares to both World Stress Map data and to a previous faulted-lithosphere, realistic-rheology dynamic model of the region computed with finite-element program Shells. No conflict is seen between the two target data sets, and the best-fitting model (using an isostatic Moho and Poisson ratio 0.5) gives minimum directional misfits relative to both targets. Constraints of computer memory, execution time and ill-conditioning of the linear system (which requires damping) limit harmonically varying tectonic stress to no more than six cycles along each axis of the model. The primary limitation on close fitting is that the Shells model predicts very sharp

Mayer Transfer Operator Approach to Selberg Zeta Function

DEFF Research Database (Denmark)

Momeni, Arash; Venkov, Alexei

. In a special situation the dynamical zeta function is defined for a geodesic flow on a hyperbolic plane quotient by an arithmetic cofinite discrete group. More precisely, the flow is defined for the corresponding unit tangent bundle. It turns out that the Selberg zeta function for this group can be expressed...... in terms of a Fredholm determinant of a classical transfer operator of the flow. The transfer operator is defined in a certain space of holomorphic functions and its matrix representation in a natural basis is given in terms of the Riemann zeta function and the Euler gamma function....

Numerical computation of aeroacoustic transfer functions for realistic airfoils

NARCIS (Netherlands)

De Santana, Leandro Dantas; Miotto, Renato Fuzaro; Wolf, William Roberto

2017-01-01

Based on Amiet's theory formalism, we propose a numerical framework to compute the aeroacoustic transfer function of realistic airfoil geometries. The aeroacoustic transfer function relates the amplitude and phase of an incoming periodic gust to the respective unsteady lift response permitting,

Robust localized-orbital transferability using the Harris functional

International Nuclear Information System (INIS)

Hierse, W.; Stechel, E.B.

1996-01-01

Replacing diagonalization in a density-functional code by an order-N algorithm does not automatically produce large efficiency gains, at least for system sizes accessible to the current generation of computers. However, both efficiency and conceptual advantages do arise from the transfer of local electronic structure between locally similar, but globally different systems. Order-N methods produce potentially transferable local electronic structure. For practical applications, it is desirable that electronic structure be transferable between subsystems of similar yet somewhat different geometry. We show, in the context of molecular deformations of a simple hydrocarbon system, that this can be accomplished by combining a transfer prescription with the Harris functional. We show proof of principle and discuss the resulting efficiency gains. copyright 1996 The American Physical Society

Exact solutions for MHD flow of couple stress fluid with heat transfer

Directory of Open Access Journals (Sweden)

Najeeb Alam Khan

2016-01-01

Full Text Available This paper aims at presenting exact solutions for MHD flow of couple stress fluid with heat transfer. The governing partial differential equations (PDEs for an incompressible MHD flow of couple stress fluid are reduced to ordinary differential equations by employing wave parameter. The methodology is implemented for linearizing the flow equations without extra transformation and restrictive assumptions. Comparison is made with the result obtained previously.

Subacute stress and chronic stress interact to decrease intestinal barrier function in rats.

Science.gov (United States)

Lauffer, Adriana; Vanuytsel, Tim; Vanormelingen, Christophe; Vanheel, Hanne; Salim Rasoel, Shadea; Tóth, Joran; Tack, Jan; Fornari, Fernando; Farré, Ricard

2016-01-01

Psychological stress increases intestinal permeability, potentially leading to low-grade inflammation and symptoms in functional gastrointestinal disorders. We assessed the effect of subacute, chronic and combined stress on intestinal barrier function and mast cell density. Male Wistar rats were allocated to four experimental groups (n = 8/group): 1/sham; 2/subacute stress (isolation and limited movement for 24 h); 3/chronic crowding stress for 14 days and 4/combined subacute and chronic stress. Jejunum and colon were collected to measure: transepithelial electrical resistance (TEER; a measure of epithelial barrier function); gene expression of tight junction molecules; mast cell density. Plasma corticosterone concentration was increased in all three stress conditions versus sham, with highest concentrations in the combined stress condition. TEER in the jejunum was decreased in all stress conditions, but was significantly lower in the combined stress condition than in the other groups. TEER in the jejunum correlated negatively with corticosterone concentration. Increased expression of claudin 1, 5 and 8, occludin and zonula occludens 1 mRNAs was detected after subacute stress in the jejunum. In contrast, colonic TEER was decreased only after combined stress, and the expression of tight junction molecules was unaltered. Increased mast cell density was observed in the chronic and combined stress condition in the colon only. In conclusion, our data show that chronic stress sensitizes the gastrointestinal tract to the effects of subacute stress on intestinal barrier function; different underlying cellular and molecular alterations are indicated in the small intestine versus the colon.

Measurement of residual stresses using fracture mechanics weight functions

International Nuclear Information System (INIS)

Fan, Y.

2000-01-01

A residual stress measurement method has been developed to quantify through-the-thickness residual stresses. Accurate measurement of residual stresses is crucial for many engineering structures. Fabrication processes such as welding and machining generate residual stresses that are difficult to predict. Residual stresses affect the integrity of structures through promoting failures due to brittle fracture, fatigue, stress corrosion cracking, and wear. In this work, the weight function theory of fracture mechanics is used to measure residual stresses. The weight function theory is an important development in computational fracture mechanics. Stress intensity factors for arbitrary stress distribution on the crack faces can be accurately and efficiently computed for predicting crack growth. This paper demonstrates that the weight functions are equally useful in measuring residual stresses. In this method, an artificial crack is created by a thin cut in a structure containing residual stresses. The cut relieves the residual stresses normal to the crack-face and allows the relieved residual stresses to deform the structure. Strain gages placed adjacent to the cut measure the relieved strains corresponding to incrementally increasing depths of the cut. The weight functions of the cracked body relate the measured strains to the residual stresses normal to the cut within the structure. The procedure details, such as numerical integration of the singular functions in applying the weight function method, will be discussed

Measurement of residual stresses using fracture mechanics weight functions

International Nuclear Information System (INIS)

Fan, Y.

2001-01-01

A residual stress measurement method has been developed to quantify through-the-thickness residual stresses. Accurate measurement of residual stresses is crucial for many engineering structures. Fabrication processes such as welding and machining generate residual stresses that are difficult to predict. Residual stresses affect the integrity of structures through promoting failures due to brittle fracture, fatigue, stress corrosion cracking, and wear. In this work, the weight function theory of fracture mechanics is used to measure residual stresses. The weight function theory is an important development in computational fracture mechanics. Stress intensity factors for arbitrary stress distribution on the crack faces can be accurately and efficiently computed for predicting crack growth. This paper demonstrates that the weight functions are equally useful in measuring residual stresses. In this method, an artificial crack is created by a thin cut in a structure containing residual stresses. The cut relieves the residual stresses normal to the crack-face and allows the relieved residual stresses to deform the structure. Strain gages placed adjacent to the cut measure the relieved strains corresponding to incrementally increasing depths of the cut. The weight functions of the cracked body relate the measured strains to the residual stresses normal to the cut within the structure. The procedure details, such as numerical integration of the singular functions in applying the weight function method, will be discussed. (author)

Racism-Related Stress, General Life Stress, and Psychological Functioning among Black American Women

Science.gov (United States)

Pieterse, Alex L.; Carter, Robert T.; Ray, Kilynda V.

2013-01-01

The relationship between general life stress, perceived racism, and psychological functioning was explored in a sample of 118 Black American women. Findings indicate that racism-related stress was not a significant predictor of psychological functioning when controlling for general life stress. Perceived racism was positively associated with…

Poverty and perceived stress: Evidence from two unconditional cash transfer programs in Zambia.

Science.gov (United States)

Hjelm, Lisa; Handa, Sudhanshu; de Hoop, Jacobus; Palermo, Tia

2017-03-01

Poverty is a chronic stressor that can lead to poor physical and mental health. This study examines whether two similar government poverty alleviation programs reduced the levels of perceived stress and poverty among poor households in Zambia. Secondary data from two cluster randomized controlled trials were used to evaluate the impacts of two unconditional cash transfer programs in Zambia. Participants were interviewed at baseline and followed over 36 months. Perceived stress among female caregivers was assessed using the Cohen Perceived Stress Scale (PSS). Poverty indicators assessed included per capita expenditure, household food security, and (nonproductive) asset ownership. Fixed effects and ordinary least squares regressions were run, controlling for age, education, marital status, household demographics, location, and poverty status at baseline. Cash transfers did not reduce perceived stress but improved economic security (per capita consumption expenditure, food insecurity, and asset ownership). Among these poverty indicators, only food insecurity was associated with perceived stress. Age and education showed no consistent association with stress, whereas death of a household member was associated with higher stress levels. In this setting, perceived stress was not reduced by a positive income shock but was correlated with food insecurity and household deaths, suggesting that food security is an important stressor in this context. Although the program did reduce food insecurity, the size of the reduction was not enough to generate a statistically significant change in stress levels. The measure used in this study appears not to be correlated with characteristics to which it has been linked in other settings, and thus, further research is needed to examine whether this widely used perceived stress measure appropriately captures the concept of perceived stress in this population. Copyright © 2017 UNICEF. Published by Elsevier Ltd.. All rights reserved.

A transfer function model of the BEPO reactor for control studies

Energy Technology Data Exchange (ETDEWEB)

Cummins, J D [Dynamics Group, Control and Instrumentation Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

1962-09-15

A spatially independent (one point) transfer function model of the BEPO reactor is presented. Perturbations in control rod reactivity and coolant flow are considered and transfer functions deduced for variations about four steady states namely zero power, one sixth full power and one sixth full flow, one sixth full power and full flow and also full power and full flow. The transfer functions are presented in pole-zero form. The use of the transfer functions in verifying experimental frequency responses, in automatic control studies and in multi-variable non-interacting control design are briefly considered. (author)

Production of lexical stress in non-native speakers of American English: kinematic correlates of stress and transfer.

Science.gov (United States)

Chakraborty, Rahul; Goffman, Lisa

2011-06-01

To assess the influence of second language (L2) proficiency on production characteristics of rhythmic sequences in the L1 (Bengali) and L2 (English), with emphasis on linguistic transfer. One goal was to examine, using kinematic evidence, how L2 proficiency influences the production of iambic and trochaic words, focusing on temporal and spatial aspects of prosody. A second goal was to assess whether prosodic structure influences judgment of foreign accent. Twenty Bengali-English bilingual individuals, 10 with low proficiency in English and 10 with high proficiency in English, and 10 monolingual English speakers, participated. Lip and jaw movements were recorded while the bilingual participants produced Bengali and English words embedded in sentences. Lower lip movement amplitude and duration were measured in trochaic and iambic words. Six native English listeners judged the nativeness of the bilingual speakers. Evidence of L1-L2 transfer was observed through duration but not amplitude cues. More proficient L2 speakers varied duration to mark iambic stress. Perceptually, the high-proficiency group received relatively higher native-like accent ratings. Trochees were judged as more native than iambs. Even in the face of L1-L2 lexical stress transfer, nonnative speakers demonstrated knowledge of prosodic contrasts. Movement duration appears to be more amenable than amplitude to modifications.

Numerical analysis of different neural transfer functions used for best approximation

International Nuclear Information System (INIS)

Gougam, L.A.; Chikhi, A.; Biskri, S.; Chafa, F.

2006-01-01

It is widely recognised that the choice of transfer functions in neural networks is of en importance to their performance. In this paper, different neural transfer functions usec approximation are discussed. We begin with sigmoi'dal functions used most often by diffi authors . At a second step, we use Gaussian functions as previously suggested in refere Finally, we deal with a specified wavelet family. A comparison between the three cases < above is made exhibiting therefore the advantages of each transfer function. The approa< function improves as the dimension N of the elementary task basis increases

Perceived stress and cognitive function in older adults: which aspect of perceived stress is important?

Science.gov (United States)

Korten, Nicole C M; Comijs, Hannie C; Penninx, Brenda W J H; Deeg, Dorly J H

2017-04-01

Few studies examined the association between perceived stress and cognitive function in older adults. This study will examine which aspects of perceived stress especially impact cognitive function. Cross-sectional data of 1099 older adults between 64 and 100 years from the Longitudinal Aging Study Amsterdam were used. Perceived stress and its subscales perceived helplessness and perceived self-efficacy were measured with the Perceived Stress Scale. Cognitive function was assessed regarding memory, processing speed and executive function. Univariate and multivariate linear regression analyses were performed between the stress measures and the domains of cognitive function. Perceived stress was associated with worse processing speed, direct and delayed recall, semantic fluency and digit span backwards (range β = -0.10; -0.11; p cognitive function, also after adjustment for depressive symptoms or sense of mastery (range β = 0.10; 0.18; p cognitive functions. Perceived self-efficacy might be an important factor in reducing stress and the prevention of cognitive decline. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Stress transfer modeling in CNT reinforced composites using continuum mechanics

International Nuclear Information System (INIS)

Chaboki Khiabani, A.; Sadrnejad, S. A.; Yahyaeii, M.

2008-01-01

Because of the substantial difference in stiffness between matrix and nano tube in CNT composite, the stress transfer between them controls their mechanical properties. This paper investigates the said issue, analytically and numerically, in axial load using representative volume element. The analytical model was established based on the modified Cox's shear lag model with the use of some simplified assumptions. Some, in the developed shear lag model, the CNT assumes hollow fiber. Solving the governing differential equation. led the high shear stress, in interface especially in the CNT cap. In addition, some finite element models were performed with different aspect ratios and the shear stress pattern especially in interface was calculated numerically. Despite some simplified assumptions that were performed with these two models such as elastic behavior and full connectivity, and the comparison of their results with other numerical models show adequate agreement

Soil transfer function obtention by Wiener's optimum filter

International Nuclear Information System (INIS)

Flores Ruiz, J.H.

1987-01-01

Transfer function in nuclear power plant Laguna Verde, Veracruz, using Wiener filter. This paper deal with identification of complex structural and soil-interaction systems often are modeling in nuclear industry. Nonparametric identification techniques are used to analyse the response of a class nonlinear vibrations. Efficient computational algorithms and experimental techniques based input-output system methods such as the Wiener-Kernel approach and least-square regression techniques are applied to get the transfer function in nuclear power plant Laguna Verde, Veracruz (Mexico) (Author)

Identification of MIMO systems with sparse transfer function coefficients

Science.gov (United States)

Qiu, Wanzhi; Saleem, Syed Khusro; Skafidas, Efstratios

2012-12-01

We study the problem of estimating transfer functions of multivariable (multiple-input multiple-output--MIMO) systems with sparse coefficients. We note that subspace identification methods are powerful and convenient tools in dealing with MIMO systems since they neither require nonlinear optimization nor impose any canonical form on the systems. However, subspace-based methods are inefficient for systems with sparse transfer function coefficients since they work on state space models. We propose a two-step algorithm where the first step identifies the system order using the subspace principle in a state space format, while the second step estimates coefficients of the transfer functions via L1-norm convex optimization. The proposed algorithm retains good features of subspace methods with improved noise-robustness for sparse systems.

Can we observe open loop transfer functions in a stochastic feedback system ?

International Nuclear Information System (INIS)

Kishida, Kuniharu; Suda, Nobuhide.

1991-01-01

There are two kinds of problems concerning open loop and closed loop transfer functions in a feedback system. One is a problem even in the deterministic case, and the other is in the stochastic case. In the deterministic case it is guaranteed under a necessary and sufficient condition that total sum of degrees of sub-transfer functions coincides to the degree of the total system. In the stochastic case a systematic understanding of a physical state model, a theoretical innovation model and a data-oriented innovation model is indispensable for determination of open loop transfer functions from time series data. Undesirable factors appear in determination of open loop transfer functions, since a transfer function matrix from input noises to output variables has a redundancy factor of diagonal matrix. (author)

Linear circuit transfer functions an introduction to fast analytical techniques

CERN Document Server

Basso, Christophe P

2016-01-01

Linear Circuit Transfer Functions: An introduction to Fast Analytical Techniques teaches readers how to determine transfer functions of linear passive and active circuits by applying Fast Analytical Circuits Techniques. Building on their existing knowledge of classical loop/nodal analysis, the book improves and expands their skills to unveil transfer functions in a swift and efficient manner. Starting with simple examples, the author explains step-by-step how expressing circuits time constants in different configurations leads to writing transfer functions in a compact and insightful way. By learning how to organize numerators and denominators in the fastest possible way, readers will speed-up analysis and predict the frequency resp nse of simple to complex circuits. In some cases, they will be able to derive the final expression by inspection, without writing a line of algebra. Key features: * Emphasizes analysis through employing time constant-based methods discussed in other text books but not widely us...

A finite volume procedure for fluid flow, heat transfer and solid-body stress analysis

KAUST Repository

Jagad, P. I.

2018-04-12

A unified cell-centered unstructured mesh finite volume procedure is presented for fluid flow, heat transfer and solid-body stress analysis. An in-house procedure (A. W. Date, Solution of Transport Equations on Unstructured Meshes with Cell-Centered Colocated Variables. Part I: Discretization, International Journal of Heat and Mass Transfer, vol. 48 (6), 1117-1127, 2005) is extended to include the solid-body stress analysis. The transport terms for a cell-face are evaluated in a structured grid-like manner. The Cartesian gradients at the center of each cell-face are evaluated using the coordinate transformation relations. The accuracy of the procedure is demonstrated by solving several benchmark problems involving different boundary conditions, source terms, and types of loading.

Executive function in cancer patients with posttraumatic stress disorder.

Science.gov (United States)

Yang, Juan; Guo, Juncheng; Jiang, Xiangling

2017-03-01

Background Cancer patients with posttraumatic stress disorder can lead to their noncompliant behaviors. However, less is known about the neurocognitive functioning of posttraumatic stress disorder in general cancer types or patient populations. The current study attempted to examine the prevalence of posttraumatic stress disorder and their relationships with executive function in individuals with cancer. Methods A total of 285 cancer patients with posttraumatic stress disorder and 150 healthy individuals were recruited for the present study. The Clinician Administered PTSD Scale, Tower of Hanoi, Wisconsin Card Sorting Test, and Wechsler Adult Intelligence Scale-Revised Chinese revision were administered to all participants. Results Significant differences in the score of Tower of Hanoi, Wisconsin Card Sorting Test, and Wechsler Adult Intelligence Scale-Revised Chinese revision were observed between the posttraumatic stress disorder group and the healthy control group ( p posttraumatic stress disorder symptoms and executive function. Conclusions These findings suggest that individuals with cancer-related posttraumatic stress disorder exhibit more severe impairment in executive function than healthy controls do.

Stress transfer of a Kevlar 49 fiber pullout test studied by micro-Raman spectroscopy.

Science.gov (United States)

Lei, Zhenkun; Wang, Quan; Qiu, Wei

2013-06-01

The interfacial stress transfer behavior of a Kevlar 49 aramid fiber-epoxy matrix was studied with fiber pullout tests, the fibers of which were stretched by a homemade microloading device. Raman spectra on the embedded fiber were recorded by micro-Raman spectroscopy, under different strain levels. Then, the fiber axial stress was obtained by the relationship between the stress and Raman shift of the aramid fiber. Experimental results revealed that the fiber axial stress increased significantly with the load. The shear stress concentration occurred at the fiber entry to the epoxy resin. Thus, interfacial friction stages exist in the debonded fiber segment, and the interfacial friction shear stress is constant within one stage. The experimental results are consistent with the theoretical model predictions.

Determination of acoustical transfer functions using an impulse method

Science.gov (United States)

MacPherson, J.

1985-02-01

The Transfer Function of a system may be defined as the relationship of the output response to the input of a system. Whilst recent advances in digital processing systems have enabled Impulse Transfer Functions to be determined by computation of the Fast Fourier Transform, there has been little work done in applying these techniques to room acoustics. Acoustical Transfer Functions have been determined for auditoria, using an impulse method. The technique is based on the computation of the Fast Fourier Transform (FFT) of a non-ideal impulsive source, both at the source and at the receiver point. The Impulse Transfer Function (ITF) is obtained by dividing the FFT at the receiver position by the FFT of the source. This quantity is presented both as linear frequency scale plots and also as synthesized one-third octave band data. The technique enables a considerable quantity of data to be obtained from a small number of impulsive signals recorded in the field, thereby minimizing the time and effort required on site. As the characteristics of the source are taken into account in the calculation, the choice of impulsive source is non-critical. The digital analysis equipment required for the analysis is readily available commercially.

Nerve Transfers for Improved Hand Function Following Cervical Spinal Cord Injury

Science.gov (United States)

the cervical spine resulting in diminished or complete loss of arm and/or hand function. Cervical SCI patients consistently rank hand function as the...most desired function above bowel and bladder function, sexual function, standing, and pain control. The overall goal of the proposed study is to...evaluate the efficacy of nerve transfers to treat patients with cervical SCIs. Over the last decade, nerve transfers have been used with increasing

TESTING SOME PEDO-TRANSFER FUNCTIONS (PTFS IN APULIA REGION

Directory of Open Access Journals (Sweden)

Floriano Buccigrossi

2009-03-01

Full Text Available The knowledge of soil water retention vs. soil water matric potential is used to study irrigation and drainage schedules, soil water storage capacity (plant available water, solute movement, plant growth and water stress. The hydraulic soil properties measuring is expensive, laborious and takes too long time, so, frequently, matemathic models, called pedo-transfer functions (PTFs are utilized to estimate hydraulic soil properties through soil chimical and phisical characteristics. Six pedo-transfer functions have been evaluated (Gupta & Larson, 1979; Rawls et al., 1982; De Jong et al., 1983; Rawls & Brakensiek, 1985; Saxton et al., 1986; Vereecken et al., 1989 by comparing estimated with measured soil moisture values at soil water matric potential of –33 and –1500 kPa of 361 soil samples collected from 185 pedons of Apulia Region (South Italy, having various combinations of particle-size distribution, soil organic matter content and bulk density. Accuracy of the soil moisture predictions have been evaluated by statistic indexes such as Weighted stantard error (WSEE, Mean Deviation (MD, Root Mean Squared Deviation (RMSD and the determination coefficient (R2 between estimated and measured water retention values. The Rawls PTF model demostrated to have the lowest values of WSEE, MD and RMSD indexes (0.044, -0.007 and 0.059 m3 H2O m-3 soil, respectively at –33 Kpa soil water matric potential (Field Capacity, while for estimating soil moisture at the Wilting Point (-1500 kPa Rawls & Brakensiek model is adequate (WSEE, MD and RMSD of 0.034, -0.016 and 0.046 m3 H2O m-3 soil. De Jong, Saxton and Rawls & Brakensiek models, at –33 kPa soil water matric potential and Gupta & Larson and De Jong models at –1500 kPa soil water matric potential, showed the highest statistic errors.

Automatic transfer function generation using contour tree controlled residue flow model and color harmonics.

Science.gov (United States)

Zhou, Jianlong; Takatsuka, Masahiro

2009-01-01

Transfer functions facilitate the volumetric data visualization by assigning optical properties to various data features and scalar values. Automation of transfer function specifications still remains a challenge in volume rendering. This paper presents an approach for automating transfer function generations by utilizing topological attributes derived from the contour tree of a volume. The contour tree acts as a visual index to volume segments, and captures associated topological attributes involved in volumetric data. A residue flow model based on Darcy's Law is employed to control distributions of opacity between branches of the contour tree. Topological attributes are also used to control color selection in a perceptual color space and create harmonic color transfer functions. The generated transfer functions can depict inclusion relationship between structures and maximize opacity and color differences between them. The proposed approach allows efficient automation of transfer function generations, and exploration on the data to be carried out based on controlling of opacity residue flow rate instead of complex low-level transfer function parameter adjustments. Experiments on various data sets demonstrate the practical use of our approach in transfer function generations.

Preliminary modulation transfer function study on amorphous silicon

International Nuclear Information System (INIS)

Khairul Anuar Mohd Salleh; Ab Razak Hamzah; Mohd Ashhar Khalid

2006-01-01

Modulation Transfer Function, (MTF) is the scientific means of evaluating the fundamental spatial resolution performance of an imaging system. In the study, the modulation transfer function of an amorphous silicon (aSi) sensor array is measured by using Edge Spread Function (ESF) Technique which is extracting a profile from the linearised image of the sharp edge. The Platinum foil is used to determine the ESF. The detector under study was a 2,304 (h) x 3,200 (v) total pixel matrix, 127 μm2 pixel pitch, 57% fill factor and using Gd2O2S:Tb Kodak Lanex Regular as the conversion screen. The ESF measurement is done by using 75 - 100 kV range of x-ray with constant mA. (Author)

Heat transfer and structure stress analysis of micro packaging component of high power light emitting diode

Directory of Open Access Journals (Sweden)

Hsu Chih-Neng

2013-01-01

Full Text Available This paper focuses on the heat transfer and structural stress analysis of the micro- scale packaging structure of a high-power light emitting diode. The thermal-effect and thermal-stress of light emitting diode are determined numerically. Light emitting diode is attached to the silicon substrate through the wire bonding process by using epoxy as die bond material. The silicon substrate is etched with holes at the bottom and filled with high conductivity copper material. The chip temperature and structure stress increase with input power consumption. The micro light emitting diode is mounted on the heat sink to increase the heat dissipation performance, to decrease chip temperature, to enhance the material structure reliability and safety, and to avoid structure failure as well. This paper has successfully used the finite element method to the micro-scale light emitting diode heat transfer and stress concentration at the edges through etched holes.

Transient thermal stresses in an orthotropic rectangular plate with convective heat transfer at upper and lower surfaces

International Nuclear Information System (INIS)

Sugano, Yoshihiro; Nakanishi, Takanori; Ito, Masahiko; Saito, Koichi.

1982-01-01

Recently, anisotropic materials have been used widely for reactor core elements and fast flying objects, therefore, the problem of thermal stress in anisotropic bodies has been studied actively. In this study, the unsteady plane thermal stress in an orthotropic rectangular thin plate heated by the temperature of ambient medium was analyzed, taking the heat transfer on both surfaces into account. The influence that the anisotropy of material constants and the heat transfer on both surfaces exert on the temperature and thermal stress of the plate was examined. Moreover, in order to investigate into the effect of the aspect ratio of the plate on the temperature and thermal stress, the unsteady distributions of temperature and thermal stress in an orthotropic semi-infinite band, of which the end surfaces are heated by ambient medium, were analyzed. The numerical calculation was carried out, and the results are shown. Before, it was difficult to satisfy the boundary condition related to shearing stress, accordingly, the analysis has not been performed, but in this study, it was shown that the analysis is possible. (Kako, I.)

Stress transfer from pile group in saturated and unsaturated soil using theoretical and experimental approaches

Directory of Open Access Journals (Sweden)

al-Omari Raid R.

2017-01-01

Full Text Available Piles are often used in groups, and the behavior of pile groups under the applied loads is generally different from that of single pile due to the interaction of neighboring piles, therefore, one of the main objectives of this paper is to investigate the influence of pile group (bearing capacity, load transfer sharing for pile shaft and tip in comparison to that of single piles. Determination of the influence of load transfer from the pile group to the surrounding soil and the mechanism of this transfer with increasing the load increment on the tip and pile shaft for the soil in saturated and unsaturated state (when there is a negative pore water pressure. Different basic properties are used that is (S = 90%, γd = 15 kN / m3, S = 90%, γd = 17 kN / m3 and S = 60%, γd =15 kN / m3. Seven model piles were tested, these was: single pile (compression and pull out test, 2×1, 3×1, 2×2, 3×2 and 3×3 group. The stress was measured with 5 cm diameter soil pressure transducer positioned at a depth of 5 cm below the pile tip for all pile groups. The measured stresses below the pile tip using a soil pressure transducer positioned at a depth of 0.25L (where L is the pile length below the pile tip are compared with those calculated using theoretical and conventional approaches. These methods are: the conventional 2V:1H method and the method used the theory of elasticity. The results showed that the method of measuring the soil stresses with soil pressure transducer adopted in this study, gives in general, good results of stress transfer compared with the results obtained from the theoretical and conventional approaches.

Better executive function under stress mitigates the effects of recent life stress exposure on health in young adults.

Science.gov (United States)

Shields, Grant S; Moons, Wesley G; Slavich, George M

2017-01-01

Executive function is a neuropsychological construct that enables controlled cognitive processing, which has been hypothesized to enhance individuals' resilience to stress. However, little empirical work has directly examined how executive function under different conditions mitigates the negative effects of stress exposure on health. To address this issue, we recruited 110 healthy young adults and assessed their recent life stress exposure, executive function in either a stressful or non-stressful context, and current health complaints. Based on existing research, we hypothesized that individuals exhibiting better executive function following a laboratory-based stressor (but not a control task) would demonstrate weaker associations between recent stress exposure and health because they perceived recent life stressors as being less severe. Consistent with this hypothesis, better executive function during acute stress, but not in the absence of stress, was associated with an attenuated link between participants' recent life stress exposure and their current health complaints. Moreover, this attenuating effect was mediated by lesser perceptions of stressor severity. Based on these data, we conclude that better executive function under stress is associated with fewer health complaints and that these effects may occur by reducing individuals' perceptions of stressor severity. The data thus suggest the possibility of reducing stress-related health problems by enhancing executive function.

Geometric optical transfer function and tis computation method

International Nuclear Information System (INIS)

Wang Qi

1992-01-01

Geometric Optical Transfer Function formula is derived after expound some content to be easily ignored, and the computation method is given with Bessel function of order zero and numerical integration and Spline interpolation. The method is of advantage to ensure accuracy and to save calculation

Statistical identification of the confidence limits of open loop transfer functions obtained by MAR analysis

International Nuclear Information System (INIS)

Antonopoulos-Domis, M.; Mourtzanos, K.

1996-01-01

Estimators of the confidence limits of open loop transfer functions via Multivariate Auto-Regressive (MAR) modelling are not available in the literature. The statistics of open loop transfer functions obtained by MAR modelling are investigated via numerical experiments. A system of known open loop transfer functions is simulated digitally and excited by random number series. The digital signals of the simulated system are then MAR modelled and the open loop transfer functions are estimated. Performing a large number of realizations, mean values and variances of the open loop transfer functions are estimated. It is found that if the record length N of each realization is long enough then the estimates of open loop transfer functions follow normal distribution. The variance of the open loop transfer functions is proportional to 1/N. For MAR processes the asymptotic covariance matrix of the estimate of open loop transfer functions was found in agreement with theoretical prediction. (author)

Transfer function and near-field detection of evanescent waves

DEFF Research Database (Denmark)

Radko, Ylia P.; Bozhevolnyi, Sergey I.; Gregersen, Niels

2006-01-01

of collection and illumination modes. Making use of a collection near-field microscope with a similar fiber tip illuminated by an evanescent field, we measure the collected power as a function of the field spatial frequency in different polarization configurations. Considering a two-dimensional probe...... for the transfer function, which is derived by introducing an effective pointof (dipolelike) detection inside the probe tip. It is found to be possible to fit reasonably well both the experimental and the simulation data for evanescent field components, implying that the developed approximation of the near......-field transfer function can serve as a simple, rational, and sufficiently reliable means of fiber probe characterization....

The transfer function model for dynamic response of wet cooling coils

International Nuclear Information System (INIS)

Yao Ye; Liu Shiqing

2008-01-01

This paper mainly concerned about the dynamic response model of wet cooling coils that is developed by the Laplace transform method. The theoretic equations are firstly established based on the theory of energy conservation. Then, the transfer functions on the transient responses of wet cooling coils have been deduced using the method of Laplace transform. The transfer functions reveal the dynamic relationships between the inlet variables and the outlet ones of the cooling coils. Partial-fraction method and Newton-Raphson method are both used in the inversion of the transfer functions from the s-domain to τ-domain. To make the dynamic model of wet cooling coils more adaptive, RBFNN method is employed to determine the coefficients of heat and mass transfer. Experiments have been done and manifested that the coefficients of heat and mass transfer by RBFNN will be of great value to the validity of the transient response model of wet cooling coils in this study

A method for the direct generation of comprehensive numerical solar building transfer functions

Energy Technology Data Exchange (ETDEWEB)

Chen, T.Y. [The Hong Kong Polytechnic University (China). Dept. of Building Services Engineering

2003-02-01

This paper describes a method for the direct generation of comprehensive numerical room transfer functions with any derived parameters as output, such as operative temperature or thermal load. Complex conductive, convective and radiant heat transfer processes, or any derived thermal parameters in buildings can be explicitly and precisely described by a generalized thermal network. This allows the s-transfer and z-transfer functions to be directly generated, using semi-symbolic analysis techniques, Cayley's expansion of determinant and Heaviside's expansion theorem. A simple algorithm is developed for finding the roots of the denominator in the inverse transform of the s-transfer functions, which ensures that no single root is missing. The techniques have been applied to generating the transfer functions of a passive solar room with floor heating. The example calculation demonstrates the high efficiency of the computational method. (author)

Microstructural stress relaxation mechanics in functionally different tendons.

Science.gov (United States)

Screen, H R C; Toorani, S; Shelton, J C

2013-01-01

Tendons experience widely varying loading conditions in vivo. They may be categorised by their function as either positional tendons, which are used for intricate movements and experience lower stress, or as energy storage tendons which act as highly stressed springs during locomotion. Structural and compositional differences between tendons are thought to enable an optimisation of their properties to suit their functional environment. However, little is known about structure-function relationships in tendon. This study adopts porcine flexor and extensor tendon fascicles as examples of high stress and low stress tendons, comparing their mechanical behaviour at the micro-level in order to understand their stress relaxation response. Stress-relaxation was shown to occur predominantly through sliding between collagen fibres. However, in the more highly stressed flexor tendon fascicles, more fibre reorganisation was evident when the tissue was exposed to low strains. By contrast, the low load extensor tendon fascicles appears to have less capacity for fibre reorganisation or shearing than the energy storage tendon, relying more heavily on fibril level relaxation. The extensor fascicles were also unable to sustain loads without rapid and complete stress relaxation. These findings highlight the need to optimise tendon repair solutions for specific tendons, and match tendon properties when using grafts in tendon repairs. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Properties of Zero-Free Transfer Function Matrices

Science.gov (United States)

D. O. Anderson, Brian; Deistler, Manfred

Transfer functions of linear, time-invariant finite-dimensional systems with more outputs than inputs, as arise in factor analysis (for example in econometrics), have, for state-variable descriptions with generic entries in the relevant matrices, no finite zeros. This paper gives a number of characterizations of such systems (and indeed square discrete-time systems with no zeros), using state-variable, impulse response, and matrix-fraction descriptions. Key properties include the ability to recover the input values at any time from a bounded interval of output values, without any knowledge of an initial state, and an ability to verify the no-zero property in terms of a property of the impulse response coefficient matrices. Results are particularized to cases where the transfer function matrix in question may or may not have a zero at infinity or a zero at zero.

A finite volume procedure for fluid flow, heat transfer and solid-body stress analysis

KAUST Repository

Jagad, P. I.; Puranik, B. P.; Date, A. W.

2018-01-01

A unified cell-centered unstructured mesh finite volume procedure is presented for fluid flow, heat transfer and solid-body stress analysis. An in-house procedure (A. W. Date, Solution of Transport Equations on Unstructured Meshes with Cell

A simplified method of evaluating the stress wave environment of internal equipment

Science.gov (United States)

Colton, J. D.; Desmond, T. P.

1979-01-01

A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.

A NON-PARAMETRIC APPROACH TO CONSTRAIN THE TRANSFER FUNCTION IN REVERBERATION MAPPING

Energy Technology Data Exchange (ETDEWEB)

Li, Yan-Rong; Wang, Jian-Min [Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China); Bai, Jin-Ming, E-mail: liyanrong@mail.ihep.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)

2016-11-10

Broad emission lines of active galactic nuclei stem from a spatially extended region (broad-line region, BLR) that is composed of discrete clouds and photoionized by the central ionizing continuum. The temporal behaviors of these emission lines are blurred echoes of continuum variations (i.e., reverberation mapping, RM) and directly reflect the structures and kinematic information of BLRs through the so-called transfer function (also known as the velocity-delay map). Based on the previous works of Rybicki and Press and Zu et al., we develop an extended, non-parametric approach to determine the transfer function for RM data, in which the transfer function is expressed as a sum of a family of relatively displaced Gaussian response functions. Therefore, arbitrary shapes of transfer functions associated with complicated BLR geometry can be seamlessly included, enabling us to relax the presumption of a specified transfer function frequently adopted in previous studies and to let it be determined by observation data. We formulate our approach in a previously well-established framework that incorporates the statistical modeling of continuum variations as a damped random walk process and takes into account long-term secular variations which are irrelevant to RM signals. The application to RM data shows the fidelity of our approach.

A NON-PARAMETRIC APPROACH TO CONSTRAIN THE TRANSFER FUNCTION IN REVERBERATION MAPPING

International Nuclear Information System (INIS)

Li, Yan-Rong; Wang, Jian-Min; Bai, Jin-Ming

2016-01-01

Broad emission lines of active galactic nuclei stem from a spatially extended region (broad-line region, BLR) that is composed of discrete clouds and photoionized by the central ionizing continuum. The temporal behaviors of these emission lines are blurred echoes of continuum variations (i.e., reverberation mapping, RM) and directly reflect the structures and kinematic information of BLRs through the so-called transfer function (also known as the velocity-delay map). Based on the previous works of Rybicki and Press and Zu et al., we develop an extended, non-parametric approach to determine the transfer function for RM data, in which the transfer function is expressed as a sum of a family of relatively displaced Gaussian response functions. Therefore, arbitrary shapes of transfer functions associated with complicated BLR geometry can be seamlessly included, enabling us to relax the presumption of a specified transfer function frequently adopted in previous studies and to let it be determined by observation data. We formulate our approach in a previously well-established framework that incorporates the statistical modeling of continuum variations as a damped random walk process and takes into account long-term secular variations which are irrelevant to RM signals. The application to RM data shows the fidelity of our approach.

Dynamic Stiffness Transfer Function of an Electromechanical Actuator Using System Identification

Science.gov (United States)

Kim, Sang Hwa; Tahk, Min-Jea

2018-04-01

In the aeroelastic analysis of flight vehicles with electromechanical actuators (EMAs), an accurate prediction of flutter requires dynamic stiffness characteristics of the EMA. The dynamic stiffness transfer function of the EMA with brushless direct current (BLDC) motor can be obtained by conducting complicated mathematical calculations of control algorithms and mechanical/electrical nonlinearities using linearization techniques. Thus, system identification approaches using experimental data, as an alternative, have considerable advantages. However, the test setup for system identification is expensive and complex, and experimental procedures for data collection are time-consuming tasks. To obtain the dynamic stiffness transfer function, this paper proposes a linear system identification method that uses information obtained from a reliable dynamic stiffness model with a control algorithm and nonlinearities. The results of this study show that the system identification procedure is compact, and the transfer function is able to describe the dynamic stiffness characteristics of the EMA. In addition, to verify the validity of the system identification method, the simulation results of the dynamic stiffness transfer function and the dynamic stiffness model were compared with the experimental data for various external loads.

Prenatal stress alters amygdala functional connectivity in preterm neonates.

Science.gov (United States)

Scheinost, Dustin; Kwon, Soo Hyun; Lacadie, Cheryl; Sze, Gordon; Sinha, Rajita; Constable, R Todd; Ment, Laura R

2016-01-01

Exposure to prenatal and early-life stress results in alterations in neural connectivity and an increased risk for neuropsychiatric disorders. In particular, alterations in amygdala connectivity have emerged as a common effect across several recent studies. However, the impact of prenatal stress exposure on the functional organization of the amygdala has yet to be explored in the prematurely-born, a population at high risk for neuropsychiatric disorders. We test the hypothesis that preterm birth and prenatal exposure to maternal stress alter functional connectivity of the amygdala using two independent cohorts. The first cohort is used to establish the effects of preterm birth and consists of 12 very preterm neonates and 25 term controls, all without prenatal stress exposure. The second is analyzed to establish the effects of prenatal stress exposure and consists of 16 extremely preterm neonates with prenatal stress exposure and 10 extremely preterm neonates with no known prenatal stress exposure. Standard resting-state functional magnetic resonance imaging and seed connectivity methods are used. When compared to term controls, very preterm neonates show significantly reduced connectivity between the amygdala and the thalamus, the hypothalamus, the brainstem, and the insula (p amygdala and the thalamus, the hypothalamus, and the peristriate cortex (p amygdala connectivity associated with preterm birth. Functional connectivity from the amygdala to other subcortical regions is decreased in preterm neonates compared to term controls. In addition, these data, for the first time, suggest that prenatal stress exposure amplifies these decreases.

Transfer of Chemically Modified Graphene with Retention of Functionality for Surface Engineering.

Science.gov (United States)

Whitener, Keith E; Lee, Woo-Kyung; Bassim, Nabil D; Stroud, Rhonda M; Robinson, Jeremy T; Sheehan, Paul E

2016-02-10

Single-layer graphene chemically reduced by the Birch process delaminates from a Si/SiOx substrate when exposed to an ethanol/water mixture, enabling transfer of chemically functionalized graphene to arbitrary substrates such as metals, dielectrics, and polymers. Unlike in previous reports, the graphene retains hydrogen, methyl, and aryl functional groups during the transfer process. This enables one to functionalize the receiving substrate with the properties of the chemically modified graphene (CMG). For instance, magnetic force microscopy shows that the previously reported magnetic properties of partially hydrogenated graphene remain after transfer. We also transfer hydrogenated graphene from its copper growth substrate to a Si/SiOx wafer and thermally dehydrogenate it to demonstrate a polymer- and etchant-free graphene transfer for potential use in transmission electron microscopy. Finally, we show that the Birch reduction facilitates delamination of CMG by weakening van der Waals forces between graphene and its substrate.

A tailored relocation stress intervention programme for family caregivers of patients transferred from a surgical intensive care unit to a general ward.

Science.gov (United States)

Lee, Seul; Oh, HyunSoo; Suh, YeonOk; Seo, WhaSook

2017-03-01

To develop and examine a relocation stress intervention programme tailored for the family caregivers of patients scheduled for transfer from a surgical intensive care unit to a general ward. Family relocation stress syndrome has been reported to be similar to that exhibited by patients, and investigators have emphasised that nurses should make special efforts to relieve family relocation stress to maximise positive contributions to the well-being of patients by family caregivers. A nonequivalent control group, nonsynchronised pretest-post-test design was adopted. The study subjects were 60 family caregivers of patients with neurosurgical or general surgical conditions in the surgical intensive care unit of a university hospital located in Incheon, South Korea. Relocation stress and family burden were evaluated at three times, that is before intervention, immediately after transfer and four to five days after transfer. This relocation stress intervention programme was developed for the family caregivers based on disease characteristics and relocation-related needs. In the experimental group, relocation stress levels significantly and continuously decreased after intervention, whereas in the control group, a slight nonsignificant trend was observed. Family burden levels in the control group increased significantly after transfer, whereas burden levels in the experimental group increased only marginally and nonsignificantly. No significant between-group differences in relocation stress or family burden levels were observed after intervention. Relocation stress levels of family caregivers were significantly decreased after intervention in the experimental group, which indicates that the devised family relocation stress intervention programme effectively alleviated family relocation stress. The devised intervention programme, which was tailored to disease characteristics and relocation-related needs, may enhance the practicality and efficacy of relocation stress

Matrix Transfer Function Design for Flexible Structures: An Application

Science.gov (United States)

Brennan, T. J.; Compito, A. V.; Doran, A. L.; Gustafson, C. L.; Wong, C. L.

1985-01-01

The application of matrix transfer function design techniques to the problem of disturbance rejection on a flexible space structure is demonstrated. The design approach is based on parameterizing a class of stabilizing compensators for the plant and formulating the design specifications as a constrained minimization problem in terms of these parameters. The solution yields a matrix transfer function representation of the compensator. A state space realization of the compensator is constructed to investigate performance and stability on the nominal and perturbed models. The application is made to the ACOSSA (Active Control of Space Structures) optical structure.

Oxidative stress markers, cognitive functions, and psychosocial functioning in bipolar disorder: an empirical cross-sectional study.

Science.gov (United States)

Aydemir, Ömer; Çubukçuoğlu, Zeynep; Erdin, Soner; Taş, Cumhur; Onur, Ece; Berk, Michael

2014-01-01

This study aimed to evaluate the relationship between oxidative stress markers and cognitive functions and domains of psychosocial functioning in bipolar disorder. Oxidative stress markers, cognitive functions, and domains of psychosocial functioning were evaluated in 51 patients with bipolar disorder who were in remission. Correlation analyses between these parameters were calculated with data controlled for duration of illness and number of episodes. There was no statistically significant correlation between oxidative stress markers and cognitive functions. In terms of psychosocial functioning, significant correlations were found between malondialdehyde and sense of stigmatization (r = -0.502); household activities and superoxide dismutase (r = 0.501); participation in social activities and nitric oxide (r = 0.414); hobbies and leisure time activities and total glutathione (r = -0.567), superoxide dismutase (r = 0.667), and neurotrophin 4 (r = 0.450); and taking initiative and self-sufficiency and superoxide dismutase (r = 0.597). There was no correlation between other domains of psychosocial functioning and oxidative stress markers. These results imply that oxidative stress markers do not appear to correlate clearly with cognitive impairment and reduced psychosocial functioning. However, there were some associations between selected oxidative markers and activity-oriented functional markers. This may represent a true negative association, or may be an artifact of oxidative stress being a state rather than a trait marker.

Oxidative stress markers, cognitive functions, and psychosocial functioning in bipolar disorder: an empirical cross-sectional study

Directory of Open Access Journals (Sweden)

Ömer Aydemir

2014-12-01

Full Text Available Objective: This study aimed to evaluate the relationship between oxidative stress markers and cognitive functions and domains of psychosocial functioning in bipolar disorder. Methods: Oxidative stress markers, cognitive functions, and domains of psychosocial functioning were evaluated in 51 patients with bipolar disorder who were in remission. Correlation analyses between these parameters were calculated with data controlled for duration of illness and number of episodes. Results: There was no statistically significant correlation between oxidative stress markers and cognitive functions. In terms of psychosocial functioning, significant correlations were found between malondialdehyde and sense of stigmatization (r = -0.502; household activities and superoxide dismutase (r = 0.501; participation in social activities and nitric oxide (r = 0.414; hobbies and leisure time activities and total glutathione (r = -0.567, superoxide dismutase (r = 0.667, and neurotrophin 4 (r = 0.450; and taking initiative and self-sufficiency and superoxide dismutase (r = 0.597. There was no correlation between other domains of psychosocial functioning and oxidative stress markers. Conclusion: These results imply that oxidative stress markers do not appear to correlate clearly with cognitive impairment and reduced psychosocial functioning. However, there were some associations between selected oxidative markers and activity-oriented functional markers. This may represent a true negative association, or may be an artifact of oxidative stress being a state rather than a trait marker.

TRANSFER-FUNCTIONS OF A LINEARIZED MULTI-REGION REACTOR

Energy Technology Data Exchange (ETDEWEB)

Higgins, Thomas J.

1963-09-15

The development of the transfer functions for a linearized multi-region reactor is studied, and an illustration is made of application of the corresponding theory by a numerical illustrative example. (auth)

Numerical study on identification of transfer functions in a feedback system and model reduction

International Nuclear Information System (INIS)

Kishida, Kuniharu

1997-01-01

Identification of transfer function matrices in a feedback system is discussed by using the singular value decomposition of Hankel matrix from the viewpoint of inverse problems. A method of model reduction is considered, and selection criteria are proposed for identification of them. Transformation formula between open loop and closed loop transfer function matrices are determined from the feedback loop structure, and they are needed for identification of open loop transfer function matrices under such a condition where the feedback system is in a minimum phase. Though the identifiability of open loop transfer function matrices can be examined in the framework of innovation model equivalent to the feedback system, there are pole-zero cancellations in the identification of them. The method to reduce a model order of an open loop transfer function is discussed by using the singular value decomposition of a gramian given by the open loop transfer function with higher degree. To check reliability of the present algorithm, a simulation study is performed for an example. (author)

Functional studies on the phosphatidychloride transfer protein

NARCIS (Netherlands)

Brouwer, A.P.M. de

2002-01-01

The phosphatidylcholine transfer protein (PC-TP) has been studied for over 30 years now. Despite extensive research concerning the biochemical, biophysical and structural properties of PC-TP, the function of this protein is still elusive. We have studied in vitro the folding and the mechanism of PC

Analysis of the transfer function for layered piezoelectric ultrasonic sensors

Directory of Open Access Journals (Sweden)

E. Gutiérrrez-Reyes

2017-06-01

Full Text Available We model theoretically the voltage response to an acoustic pulse of a multilayer system forming a low noise capacitive sensor including a Polyvinylidene Fluoride piezoelectric film. First we model a generic piezoelectric detector consisting of a piezoelectric film between two metallic electrodes that are the responsible to convert the acoustic signal into a voltage signal. Then we calculate the pressure-to-voltage transfer function for a N-layer piezo-electric capacitor detector, allowing to study the effects of the electrode and protective layers thickness in typical layered piezoelectric sensors. The derived transfer function, when multiplied by the Fourier transform of the incident acoustic pulse, gives the voltage electric response in the frequency domain. An important concern regarding the transfer function is that it may have zeros at specific frequencies, and thus inverting the voltage Fourier transform of the pulse to recover the pressure signal in the time domain is not always, in principle, possible. Our formulas can be used to predict the existence and locations of such zeroes. We illustrate the use of the transfer function by predicting the electric signal generated at a multilayer piezoelectric sensor to an ultrasonic pulse generated photoacoustically by a laser pulse at a three media system with impedance mismatch. This theoretical calculations are compared with our own experimental measurements.

Extremely environment-hard and low work function transfer-mold field emitter arrays

Energy Technology Data Exchange (ETDEWEB)

Nakamoto, Masayuki, E-mail: m-nakamoto@rie.shizuoka.ac.jp [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8011 (Japan); Moon, Jonghyun [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8011 (Japan)

2013-06-15

Extremely environment-hard and low work function field-emitter arrays (FEAs) were fabricated by a transfer-mold emitter fabrication method to produce highly reliable vacuum nanoelectronic devices able to operate stably at low voltage in highly oxidizing atmospheres. Amorphous carbon (a-C) having a work function of 3.6 eV and sp{sup 3} fraction of 85.6% prepared by plasma-enhanced chemical vapor deposition was used as the emitter material. The field-emission characteristics of the obtained transfer-mold FEAs strongly depended on their work function and morphology. The environment-hard characteristics of the transfer-mold a-C FEAs were compared with those of the transfer-mold titanium nitride FEAs and nickel FEAs. X-ray photoelectron spectroscopy was used to confirm the stable chemical states of the FEAs after oxygen radical treatment. The small amount of material oxidized (6.3%) at the surface of the a-C FEAs compared with 11.8% for the TiN-FEAs and 39.0% for Ni FEAs after oxygen radical treatment explained their almost constant work function in oxidizing atmospheres. The emission fluctuation rates of transfer-mold a-C FEAs without resistive layers under in situ radical treatment were as low as ±5.0%, compared with 5–100% for conventional FEAs with resistive layers not under highly oxidizing atmospheres. Therefore, the present environment-hard and low work function transfer-mold a-C FEAs are expected to be useful for reliable vacuum nanoelectronic devices.

Determination of the transfer function for optical surface topography measuring instruments—a review

International Nuclear Information System (INIS)

Foreman, Matthew R; Török, Peter; Giusca, Claudiu L; Leach, Richard K; Coupland, Jeremy M

2013-01-01

A significant number of areal surface topography measuring instruments, largely based on optical techniques, are commercially available. However, implementation of optical instrumentation into production is currently difficult due to the lack of understanding of the complex interaction between the light and the component surface. Studying the optical transfer function of the instrument can help address this issue. Here a review is given of techniques for the measurement of optical transfer functions. Starting from the basis of a spatially coherent, monochromatic confocal scanning imaging system, the theory of optical transfer functions in three-dimensional (3D) imaging is presented. Further generalizations are reviewed allowing the extension of the theory to the description of conventional and interferometric 3D imaging systems. Polychromatic transfer functions and surface topography measurements are also discussed. Following presentation of theoretical results, experimental methods to measure the optical transfer function of each class of system are presented, with a focus on suitable methods for the establishment of calibration standards in 3D imaging and surface topography measurements. (topical review)

Frequency and Wavevector Dependence of the Atomic Level Stress-Stress Correlation Function in a Model Supercooled Liquid

Science.gov (United States)

Levashov, Valentin A.; Morris, James R.; Egami, Takeshi

2012-02-01

Temporal and spatial correlations among the local atomic level shear stresses were studied for a model liquid iron by molecular dynamics simulation [PRL 106,115703]. Integration over time and space of the shear stress correlation function F(r,t) yields viscosity via Green-Kubo relation. The stress correlation function in time and space F(r,t) was Fourier transformed to study the dependence on frequency, E, and wave vector, Q. The results, F(Q,E), showed damped shear stress waves propagating in the liquid for small Q at high and low temperatures. We also observed additional diffuse feature that appears as temperature is reduced below crossover temperature of potential energy landscape at relatively low frequencies at small Q. We suggest that this additional feature might be related to dynamic heterogeneity and boson peaks. We also discuss a relation between the time-scale of the stress-stress correlation function and the alpha-relaxation time of the intermediate self-scattering function S(Q,E).

Effects of work stress and home stress on autonomic nervous function in Japanese male workers.

Science.gov (United States)

Maeda, Eri; Iwata, Toyoto; Murata, Katsuyuki

2015-01-01

Autonomic imbalance is one of the important pathways through which psychological stress contributes to cardiovascular diseases/sudden death. Although previous studies have focused mainly on stress at work (work stress), the association between autonomic function and stress at home (home stress) is still poorly understood. The purpose was to clarify the effect of work/home stress on autonomic function in 1,809 Japanese male workers. We measured corrected QT (QTc) interval and QT index on the electrocardiogram along with blood pressure and heart rate. Participants provided self-reported information about the presence/absence of work/home stress and the possible confounders affecting QT indicators. Home stress was related positively to QT index (p=0.040) after adjusting for the possible confounders, though work stress did not show a significant relation to QTc interval or QT index. The odds ratio of home stress to elevated QT index (≥105) was 2.677 (95% CI, 1.050 to 6.822). Work/home stress showed no significant relation to blood pressure or heart rate. These findings suggest that autonomic imbalance, readily assessed by QT indicators, can be induced by home stress in Japanese workers. Additional research is needed to identify different types of home stress that are strongly associated with autonomic imbalance.

Band extension in digital methods of transfer function determination – signal conditioners asymmetry error corrections

Directory of Open Access Journals (Sweden)

Zbigniew Staroszczyk

2014-12-01

Full Text Available [b]Abstract[/b]. In the paper, the calibrating method for error correction in transfer function determination with the use of DSP has been proposed. The correction limits/eliminates influence of transfer function input/output signal conditioners on the estimated transfer functions in the investigated object. The method exploits frequency domain conditioning paths descriptor found during training observation made on the known reference object.[b]Keywords[/b]: transfer function, band extension, error correction, phase errors

Heat Transfer Performance of Functionalized Graphene Nanoplatelet Aqueous Nanofluids

Directory of Open Access Journals (Sweden)

Roberto Agromayor

2016-06-01

Full Text Available The low thermal conductivity of fluids used in many industrial applications is one of the primary limitations in the development of more efficient heat transfer systems. A promising solution to this problem is the suspension of nanoparticles with high thermal conductivities in a base fluid. These suspensions, known as nanofluids, have great potential for enhancing heat transfer. The heat transfer enhancement of sulfonic acid-functionalized graphene nanoplatelet water-based nanofluids is addressed in this work. A new experimental setup was designed for this purpose. Convection coefficients, pressure drops, and thermophysical properties of various nanofluids at different concentrations were measured for several operational conditions and the results are compared with those of pure water. Enhancements in thermal conductivity and in convection heat transfer coefficient reach 12% (1 wt % and 32% (0.5 wt %, respectively. New correlations capable of predicting the Nusselt number and the friction factor of this kind of nanofluid as a function of other dimensionless quantities are developed. In addition, thermal performance factors are obtained from the experimental convection coefficient and pressure drop data in order to assess the convenience of replacing the base fluid with designed nanofluids.

Functional knowledge transfer for high-accuracy prediction of under-studied biological processes.

Directory of Open Access Journals (Sweden)

Christopher Y Park

Full Text Available A key challenge in genetics is identifying the functional roles of genes in pathways. Numerous functional genomics techniques (e.g. machine learning that predict protein function have been developed to address this question. These methods generally build from existing annotations of genes to pathways and thus are often unable to identify additional genes participating in processes that are not already well studied. Many of these processes are well studied in some organism, but not necessarily in an investigator's organism of interest. Sequence-based search methods (e.g. BLAST have been used to transfer such annotation information between organisms. We demonstrate that functional genomics can complement traditional sequence similarity to improve the transfer of gene annotations between organisms. Our method transfers annotations only when functionally appropriate as determined by genomic data and can be used with any prediction algorithm to combine transferred gene function knowledge with organism-specific high-throughput data to enable accurate function prediction. We show that diverse state-of-art machine learning algorithms leveraging functional knowledge transfer (FKT dramatically improve their accuracy in predicting gene-pathway membership, particularly for processes with little experimental knowledge in an organism. We also show that our method compares favorably to annotation transfer by sequence similarity. Next, we deploy FKT with state-of-the-art SVM classifier to predict novel genes to 11,000 biological processes across six diverse organisms and expand the coverage of accurate function predictions to processes that are often ignored because of a dearth of annotated genes in an organism. Finally, we perform in vivo experimental investigation in Danio rerio and confirm the regulatory role of our top predicted novel gene, wnt5b, in leftward cell migration during heart development. FKT is immediately applicable to many bioinformatics

Weight functions for the determination of stress intensity factor and T-stress for edge-cracked plates with built-in ends

International Nuclear Information System (INIS)

Li, J.; Wang, X.; Tan, C.L.

2004-01-01

This paper presents the weight functions for the determination of the stress intensity factor and T-stress solutions for edge-cracked plates with built-in ends under complex stress distributions. First, a compliance analysis approach is used to calculate stress intensity factor and T-stress for edge cracks in finite width plates with built-in ends with uniform or linear stress distributions acting on the crack face. The results serve as the reference solutions for the next step in which the approaches of deriving weight functions from reference stress intensity factor and T-stress solutions developed for stress boundary conditions are extended to obtain the corresponding weight functions for edge-cracked plates with built-in ends. Finite element analysis is conducted to validate the derived solutions. The weight functions derived are suitable for obtaining stress intensity factors and T-stress solutions under any complex stress field

Influence of Stress Shape Function on Analysis of Contact Problem Using Hybrid Photoelasticity

International Nuclear Information System (INIS)

Shin, Dongchul; Hawong, Jaisug

2013-01-01

In this research, a study on stress shape functions was conducted to analyze the contact stress problem by using a hybrid photoelasticity. Because the contact stress problem is generally solved as a half-plane problem, the relationship between two analytical stress functions, which are compositions of the Airy stress function, was similar to one of the crack problem. However, this relationship in itself could not be used to solve the contact stress problem (especially one with singular points). Therefore, to analyze the contact stress problem more correctly, stress shape functions based on the condition of two contact end points had to be considered in the form of these two analytical stress functions. The four types of stress shape functions were related to the stress singularities at the two contact end points. Among them, the primary two types used for the analysis of an O-ring were selected, and their validities were verified in this work

Modelling of Multi Input Transfer Function for Rainfall Forecasting in Batu City

OpenAIRE

Priska Arindya Purnama

2017-01-01

The aim of this research is to model and forecast the rainfall in Batu City using multi input transfer function model based on air temperature, humidity, wind speed and cloud. Transfer function model is a multivariate time series model which consists of an output series (Yt) sequence expected to be effected by an input series (Xt) and other inputs in a group called a noise series (Nt). Multi input transfer function model obtained is (b1,s1,r1) (b2,s2,r2) (b3,s3,r3) (b4,s4,r4)(pn,qn) = (0,0,0)...

Spatially distributed flame transfer functions for predicting combustion dynamics in lean premixed gas turbine combustors

Energy Technology Data Exchange (ETDEWEB)

Kim, K.T.; Lee, J.G.; Quay, B.D.; Santavicca, D.A. [Center for Advanced Power Generation, Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA (United States)

2010-09-15

The present paper describes a methodology to improve the accuracy of prediction of the eigenfrequencies and growth rates of self-induced instabilities and demonstrates its application to a laboratory-scale, swirl-stabilized, lean-premixed, gas turbine combustor. The influence of the spatial heat release distribution is accounted for using local flame transfer function (FTF) measurements. The two-microphone technique and CH{sup *} chemiluminescence intensity measurements are used to determine the input (inlet velocity perturbation) and the output functions (heat release oscillation), respectively, for the local flame transfer functions. The experimentally determined local flame transfer functions are superposed using the flame transfer function superposition principle, and the result is incorporated into an analytic thermoacoustic model, in order to predict the linear stability characteristics of a given system. Results show that when the flame length is not acoustically compact the model prediction calculated using the local flame transfer functions is better than the prediction made using the global flame transfer function. In the case of a flame in the compact flame regime, accurate predictions of eigenfrequencies and growth rates can be obtained using the global flame transfer function. It was also found that the general response characteristics of the local FTF (gain and phase) are qualitatively the same as those of the global FTF. (author)

Modelling of Multi Input Transfer Function for Rainfall Forecasting in Batu City

Directory of Open Access Journals (Sweden)

Priska Arindya Purnama

2017-11-01

Full Text Available The aim of this research is to model and forecast the rainfall in Batu City using multi input transfer function model based on air temperature, humidity, wind speed and cloud. Transfer function model is a multivariate time series model which consists of an output series (Yt sequence expected to be effected by an input series (Xt and other inputs in a group called a noise series (Nt. Multi input transfer function model obtained is (b1,s1,r1 (b2,s2,r2 (b3,s3,r3 (b4,s4,r4(pn,qn = (0,0,0 (23,0,0 (1,2,0 (0,0,0 ([5,8],2 and shows that air temperature on t-day affects rainfall on t-day, rainfall on t-day is influenced by air humidity in the previous 23 days, rainfall on t-day is affected by wind speed in the previous day , and rainfall on day t is affected by clouds on day t. The results of rainfall forecasting in Batu City with multi input transfer function model can be said to be accurate, because it produces relatively small RMSE value. The value of RMSE data forecasting training is 7.7921 while forecasting data testing is 4.2184. Multi-input transfer function model is suitable for rainfall in Batu City.

Clinical validity of a relocation stress scale for the families of patients transferred from intensive care units.

Science.gov (United States)

Oh, HyunSoo; Lee, Seul; Kim, JiSun; Lee, EunJu; Min, HyoNam; Cho, OkJa; Seo, WhaSook

2015-07-01

This study was conducted to develop a family relocation stress scale by modifying the Son's Relocation Stress Syndrome Scale, to examine its clinical validity and reliability and to confirm its suitability for measuring family relocation stress. The transfer of ICU patients to general wards is a significant anxiety-producing event for family members. However, no relocation stress scale has been developed specifically for families. A nonexperimental, correlation design was adopted. The study subjects were 95 family members of 95 ICU patients at a university hospital located in Incheon, South Korea. Face and construct validities of the devised family relocation stress scale were examined. Construct validity was examined using factor analysis and by using a nomological validity test. Reliability was also examined. Face and content validity of the scale were verified by confirming that its items adequately measured family relocation stress. Factor analysis yielded four components, and the total variance explained by these four components was 63·0%, which is acceptable. Nomological validity was well supported by significant relationships between relocation stress and degree of preparation for relocation, patient self-care ability, family burden and satisfaction with the relocation process. The devised scale was also found to have good reliability. The family relocation stress scale devised in this study was found to have good validity and reliability, and thus, is believed to offer a means of assessing family relocation stress. The findings of this study provide a reliable and valid assessment tool when nurses prepare families for patient transfer from an ICU to a ward setting, and may also provide useful information to those developing an intervention programme for family relocation stress management. © 2015 John Wiley & Sons Ltd.

Direct metal transfer printing on flexible substrate for fabricating optics functional devices

Science.gov (United States)

Jiang, Yingjie; Zhou, Xiaohong; Zhang, Feng; Shi, Zhenwu; Chen, Linsen; Peng, Changsi

2015-11-01

New functional materials and devices based on metal patterns can be widely used in many new and expanding industries,such as flat panel displays, alternative energy,sensors and so on. In this paper, we introduce a new transfer printing method for fabricating metal optics functional devices. This method can directly transfer a metal pattern from a polyethylene terephthalate (PET)supported UV or polydimethylsiloxane (PDMS) pattern to another PET substrate. Purely taking advantage of the anaerobic UV curing adhesive (a-UV) on PET substrate, metal film can be easily peeled off from micro/nano-structured surface. As a result, metal film on the protrusion can be selectively transferred onto the target substrate, to make it the metal functional surface. But which on the bottom can not be transferred. This method provides low cost fabrication of metal thin film devices by avoiding high cost lithography process. Compared with conventional approach, this method can get more smooth rough edges and has wider tolerance range for the original master mold. Future developments and potential applications of this metal transfer method will be addressed.

Time constants and transfer functions for a homogeneous 900 MWt metallic fueled LMR

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1988-01-01

Nodal transfer functions are calculated for a 900 MWt U10Zr-fueled sodium cooled reactor. From the transfer functions the time constants, feedback reactivity transfer function coefficients, and power coefficients can be determined. These quantities are calculated for core fuel, upper and lower axial reflector steel, radial blanket fuel, radial reflector steel, and B 4 C rod shaft expansion effect. The quantities are compared to the analogous quantities of a 60 MWt metallic-fueled sodium cooled Experimental Breeder Reactor II configuration. 8 refs., 2 figs., 6 tabs

Multiconfiguration Pair-Density Functional Theory Outperforms Kohn-Sham Density Functional Theory and Multireference Perturbation Theory for Ground-State and Excited-State Charge Transfer.

Science.gov (United States)

Ghosh, Soumen; Sonnenberger, Andrew L; Hoyer, Chad E; Truhlar, Donald G; Gagliardi, Laura

2015-08-11

The correct description of charge transfer in ground and excited states is very important for molecular interactions, photochemistry, electrochemistry, and charge transport, but it is very challenging for Kohn-Sham (KS) density functional theory (DFT). KS-DFT exchange-correlation functionals without nonlocal exchange fail to describe both ground- and excited-state charge transfer properly. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory with a new type of density functional called an on-top density functional. Here we have used MC-PDFT to study challenging ground- and excited-state charge-transfer processes by using on-top density functionals obtained by translating KS exchange-correlation functionals. For ground-state charge transfer, MC-PDFT performs better than either the PBE exchange-correlation functional or CASPT2 wave function theory. For excited-state charge transfer, MC-PDFT (unlike KS-DFT) shows qualitatively correct behavior at long-range with great improvement in predicted excitation energies.

Selberg zeta functions and transfer operators an experimental approach to singular perturbations

CERN Document Server

Fraczek, Markus Szymon

2017-01-01

This book presents a method for evaluating Selberg zeta functions via transfer operators for the full modular group and its congruence subgroups with characters. Studying zeros of Selberg zeta functions for character deformations allows us to access the discrete spectra and resonances of hyperbolic Laplacians under both singular and non-singular perturbations. Areas in which the theory has not yet been sufficiently developed, such as the spectral theory of transfer operators or the singular perturbation theory of hyperbolic Laplacians, will profit from the numerical experiments discussed in this book. Detailed descriptions of numerical approaches to the spectra and eigenfunctions of transfer operators and to computations of Selberg zeta functions will be of value to researchers active in analysis, while those researchers focusing more on numerical aspects will benefit from discussions of the analytic theory, in particular those concerning the transfer operator method and the spectral theory of hyperbolic spac...

Steep and Adjustable Transfer Functions of Monolithic SOA-EA 2R-Regenerators

DEFF Research Database (Denmark)

Öhman, Filip; Kjær, Rasmus; Christiansen, Lotte Jin

2006-01-01

of a semiconductor waveguide with alternating amplifier and absorber sections using quantum-well active material. The steep nonlinearity of the transfer function is achieved by concatenating several sections. We identify the saturation properties of the absorbing media, as dictated by the band-filling and field......Measurements and numerical modeling of a reamplification and reshaping (2R) regenerator demonstrate a steep power transfer function with adjustable threshold. The threshold can be adjusted more than 6 dB by simple control of the reverse bias voltage of the absorber section. The device consists...... screening, as important for the observed transfer functions. The relation of the saturation powers of the gain and absorption sectionsis important for design optimization....

Thermal and mechanical stresses in a functionally graded thick sphere

International Nuclear Information System (INIS)

Eslami, M.R.; Babaei, M.H.; Poultangari, R.

2005-01-01

In this paper, a general solution for the one-dimensional steady-state thermal and mechanical stresses in a hollow thick sphere made of functionally graded material is presented. The temperature distribution is assumed to be a function of radius, with general thermal and mechanical boundary conditions on the inside and outside surfaces of the sphere. The material properties, except Poisson's ratio, are assumed to vary along the radius r according to a power law function. The analytical solution of the heat conduction equation and the Navier equation lead to the temperature profile, radial displacement, radial stress, and hoop stress as a function of radial direction

An analytical wall-function for recirculating and impinging turbulent heat transfer

International Nuclear Information System (INIS)

Suga, K.; Ishibashi, Y.; Kuwata, Y.

2013-01-01

Highlights: ► Improvement of the analytical wall-function is proposed. ► Strain parameter dependency is introduced to the prescribed eddy viscosity profile of the analytical wall-function. ► The model performance is evaluated in turbulent pipe, channel, back-step, abrupt expansion pipe and plane impinging flows. ► Generally improved heat transfer is obtained in all the test cases with the standard k-e model. -- Abstract: The performance of the analytical wall-function (AWF) of Craft et al. [Craft, T.J., Gerasimov, A.V., Iacovides, H., Launder, B.E., 2002, Progress in the generalisation of wall-function treatments. Int. J. Heat Fluid Flow 23, 148–160.] is improved for predicting turbulent heat transfer in recirculating and impinging flows. Since constant parameters of the eddy viscosity formula were used to derive the AWF, the prediction accuracy of the original AWF tends to deteriorate in complex flows where those parameters need changing according to the local turbulence. To overcome such shortcomings, the present study introduces a functional behaviour on the strain parameter into the coefficient of the eddy viscosity of the AWF. The presently modified version of the AWF is validated in turbulent heat transfer of pipe flows, channel flows, back-step flows, pipe flows with abrupt expansion and plane impinging slot jets. The results confirm that the present modification successfully improves the performance of the original AWF for all the flows and heat transfer tested

Radial transfer effects for poloidal rotation

Science.gov (United States)

Hallatschek, Klaus

2010-11-01

Radial transfer of energy or momentum is the principal agent responsible for radial structures of Geodesic Acoustic Modes (GAMs) or stationary Zonal Flows (ZF) generated by the turbulence. For the GAM, following a physical approach, it is possible to find useful expressions for the individual components of the Poynting flux or radial group velocity allowing predictions where a mathematical full analysis is unfeasible. Striking differences between up-down symmetric flux surfaces and asymmetric ones have been found. For divertor geometries, e.g., the direction of the propagation depends on the sign of the ion grad-B drift with respect to the X-point, reminiscent of a sensitive determinant of the H-mode threshold. In nonlocal turbulence computations it becomes obvious that the linear energy transfer terms can be completely overwhelmed by the action of the turbulence. In contrast, stationary ZFs are governed by the turbulent radial transfer of momentum. For sufficiently large systems, the Reynolds stress becomes a deterministic functional of the flows, which can be empirically determined from the stress response in computational turbulence studies. The functional allows predictions even on flow/turbulence states not readily obtainable from small amplitude noise, such as certain transport bifurcations or meta-stable states.

Effect of lamotrigine, oxcarbazepine and topiramate on cognitive functions and oxidative stress in PTZ-kindled mice.

Science.gov (United States)

Agarwal, Nidhi Bharal; Agarwal, Nitin Kumar; Mediratta, Pramod Kumari; Sharma, Krishna Kishore

2011-04-01

Cognitive impairment is frequently observed in epileptic patients. It has been seen that not only epilepsy but antiepileptic drugs also impair cognitive functions. The present study was undertaken to assess the effect of three anticonvulsants viz. lamotrigine (5mg/kg, p.o.), oxcarbazepine (15mg/kg, p.o.) and topiramate (10mg/kg, p.o.) on cognitive function and oxidative stress during pentylenetetrazole (PTZ)-kindling in mice. Kindling was induced by the administration of PTZ (25mg/kg, i.p.) on every alternate day till 5 weeks. Cognition was assessed after the development of kindling. Elevated plus maze (EPM) and passive avoidance response (PAR) tests were carried out after 24h and 48h of the last PTZ administration. After completion of behavioural tests malondialdehyde (MDA), glutathione levels, superoxide dismutase and catalase activity were measured as an indicator of oxidative stress. The results of the present study indicate that topiramate (10mg/kg) administration to kindled animals increased transfer latency and decreased step-down latency in EPM and PAR tests, respectively. However, lamotrigine and oxcarbazepine did not alter the two parameters. Topiramate administration to kindled as well as non-kindled animals has shown increase in MDA and decrease in glutathione levels. Lamotrigine and oxcarbazepine did not show significant alteration in oxidative stress parameters. To conclude, long term administration of topiramate impairs cognitive functions during experimental epilepsy while lamotrigine and oxcarbazepine are safer. Copyright © 2010 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Transfer function restoration in 3D electron microscopy via iterative data refinement

International Nuclear Information System (INIS)

Sorzano, C O S; Marabini, R; Herman, G T; Censor, Y; Carazo, J M

2004-01-01

Three-dimensional electron microscopy (3D-EM) is a powerful tool for visualizing complex biological systems. As with any other imaging device, the electron microscope introduces a transfer function (called in this field the contrast transfer function, CTF) into the image acquisition process that modulates the various frequencies of the signal. Thus, the 3D reconstructions performed with these CTF-affected projections are also affected by an implicit 3D transfer function. For high-resolution electron microscopy, the effect of the CTF is quite dramatic and limits severely the achievable resolution. In this work we make use of the iterative data refinement (IDR) technique to ameliorate the effect of the CTF. It is demonstrated that the approach can be successfully applied to noisy data

Chronic stress and neural function: accounting for sex and age.

Science.gov (United States)

Luine, V N; Beck, K D; Bowman, R E; Frankfurt, M; Maclusky, N J

2007-10-01

Cognitive responses to stress follow the temporally dependent pattern originally established by Selye (1) wherein short-term stressors elicit adaptive responses whereas continued stress (chronic) results in maladaptive changes--deleterious effects on physiological systems and impaired cognition. However, this pattern for cognitive effects appears to apply to only half the population (males) and, more specifically, to young, adult males. Females show different cognitive responses to stress. In contrast to impaired cognition in males after chronic stress, female rodents show enhanced performance on the same memory tasks after the same stress. Not only cognition, but anxiety, shows sex-dependent changes following chronic stress--stress is anxiolytic in males and anxiogenic in females. Moreover, behavioral responses to chronic stress are different in developing as well as aging subjects (both sexes) as compared to adults. In aged rats, chronic stress enhances recognition memory in both sexes, does not alter spatial memory, and anxiety effects are opposite to young adults. When pregnant dams are exposed to chronic stress, at adulthood the offspring display yet different consequences of stress on anxiety and cognition, and, in contrast to adulthood when the behavioral effects of stress are reversible, prenatal stress effects appear enduring. Changing levels of estradiol in the sexes over the lifespan appear to contribute to the differences in response to stress. Thus, theories of stress dependent modulations in CNS function--developed solely in male models, focused on peripheral physiological processes and tested in adults--may require revision when applied to a more diverse population (age- and sex-wise) at least in relation to the neural functions of cognition and anxiety. Moreover, these results suggest that other stressors and neural functions should be investigated to determine whether age, sex and gonadal hormones also have an impact.

Polymer-coated compliant receivers for intact laser-induced forward transfer of thin films: experimental results and modelling

Science.gov (United States)

Feinaeugle, Matthias; Horak, Peter; Sones, Collin L.; Lippert, Thomas; Eason, Rob W.

2014-09-01

In this study, we investigate both experimentally and numerically laser-induced forward transfer (LIFT) of thin films to determine the role of a thin polymer layer coating the receiver with the aim of modifying the rate of deceleration and reduction of material stress preventing intact material transfer. A numerical model of the impact phase during LIFT shows that such a layer reduces the modelled stress. The evolution of stress within the transferred deposit and the substrate as a function of the thickness of the polymer layer, the transfer velocity and the elastic properties of the polymer are evaluated. The functionality of the polymer layer is verified experimentally by LIFT printing intact 1- m-thick bismuth telluride films and polymeric light-emitting diode pads onto a layer of 12-m-thick polydimethylsiloxane and 50-nm-thick poly(3,4-ethylenedioxythiophene) blended with poly(styrenesulfonate) (PEDOT:PSS), respectively. Furthermore, it is demonstrated experimentally that the introduction of such a compliant layer improves adhesion between the deposit and its substrate.

PHENOMENOLOGICAL INQUIRY AND SELF-FUNCTIONS IN THE TRANSFERENCE-COUNTERTRANSFERENCE MILIEU

Directory of Open Access Journals (Sweden)

Richard G. Erskine

2013-05-01

Full Text Available The article “Balancing on the ‘Borderline’ of Early Affect-Confusion: Part 2 of a Case Study Trilogy” serves as the basis for this rejoinder and collegial discourse. The organizing-functions of reparation, stabilization, regulation, and enhancement are described and placed within the transference-countertransference milieu. Examples of bifurcating client’s questions to resolve transference are provided.

Protective effect of low dose caffeine on psychological stress and cognitive function.

Science.gov (United States)

Çakır, Özgür Kasımay; Ellek, Nurfitnat; Salehin, Nabila; Hamamcı, Rabia; Keleş, Hülya; Kayalı, Damla Gökçeoğlu; Akakın, Dilek; Yüksel, Meral; Özbeyli, Dilek

2017-01-01

Caffeine is an adrenergic antagonist that enhances neuronal activity. Psychological stress depresses cognitive function. To investigate the effects of acute and chronic low dose caffeine on anxiety-like behavior and cognitive functions of acute or chronic psychological stressed rats. Acute or chronic caffeine (3mg/kg) was administered to male Sprague Dawley rats (200-250g, n=42) before acute (cat odor) and chronic variable psychological stress (restraint overcrowding stress, elevated plus maze, cat odor, forced swimming) induction. Anxiety and cognitive functions were evaluated by hole-board and object recognition tests. The brain glutathione and malondialdehyde assays, myeloperoxidase, nitric oxide (NO), superoxide dismutase (SOD), luminol and lucigenin activity and histological examination were done. ANOVA and Student's t-test were used for statistical analysis. The depressed cognitive function with chronic stress exposure and the increased anxiety-like behavior with both stress inductions were improved via both caffeine applications (pcaffeine pretreatments in chronic stressed rats, and chronic caffeine in acute stressed ones reduced the elevated myeloperoxidase activities (pcaffeine (pcaffeine (pcaffeine decreased SOD activity (pcaffeine. The increased anxiety-like behavior and depleted cognitive functions under stress conditions were improved with both acute and predominantly chronic caffeine pretreatments by decreasing oxidative damage parameters. Copyright © 2016 Elsevier Inc. All rights reserved.

Defoliation of interior Douglas-fir elicits carbon transfer and stress signalling to ponderosa pine neighbors through ectomycorrhizal networks.

Science.gov (United States)

Song, Yuan Yuan; Simard, Suzanne W; Carroll, Allan; Mohn, William W; Zeng, Ren Sen

2015-02-16

Extensive regions of interior Douglas-fir (Pseudotsuga menziesii var. glauca, IDF) forests in North America are being damaged by drought and western spruce budworm (Choristoneura occidentalis). This damage is resulting from warmer and drier summers associated with climate change. To test whether defoliated IDF can directly transfer resources to ponderosa pine (Pinus ponderosae) regenerating nearby, thus aiding in forest recovery, we examined photosynthetic carbon transfer and defense enzyme response. We grew pairs of ectomycorrhizal IDF 'donor' and ponderosa pine 'receiver' seedlings in pots and isolated transfer pathways by comparing 35 μm, 0.5 μm and no mesh treatments; we then stressed IDF donors either through manual defoliation or infestation by the budworm. We found that manual defoliation of IDF donors led to transfer of photosynthetic carbon to neighboring receivers through mycorrhizal networks, but not through soil or root pathways. Both manual and insect defoliation of donors led to increased activity of peroxidase, polyphenol oxidase and superoxide dismutase in the ponderosa pine receivers, via a mechanism primarily dependent on the mycorrhizal network. These findings indicate that IDF can transfer resources and stress signals to interspecific neighbors, suggesting ectomycorrhizal networks can serve as agents of interspecific communication facilitating recovery and succession of forests after disturbance.

Pregnancy following nonsurgical donor ovum transfer to a functionally agonadal woman

International Nuclear Information System (INIS)

Sauer, M.V.; Macaso, T.M.; Ishida, E.H.; Giudice, L.; Marshall, J.R.; Buster, J.E.

1987-01-01

We report this country's first nonsurgical donor ovum transfer pregnancy in a functionally agonadal woman who had received chemotherapy and radiation for Hodgkin's lymphoma. For women with ovarian failure, nonsurgical uterine lavage and ovum transfer may provide an opportunity for motherhood that was not possible previously

Transfer function synthesis for reactor spatial dynamics using the modal approach

Energy Technology Data Exchange (ETDEWEB)

Guppy, C B [Control and Instrumentation Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

1962-08-15

Techniques are developed below which will enable the construction of transfer functions relating changes in variables such as power or neutron flux with reactivity perturbations when there is a need for taking into account spatial effects within a reactor. Initially each of the transfer functions derived comprises the sum of a series of harmonics each of which has a laplace transform with associated spatial eigenfunction. Series of this kind can then be reduced to pure polynomial form (numerators on denominators) the coefficients of which have implicit allowance for spatial effects. The existence of large reactors having several independent controllers make necessary knowledge of transfer functions of this form. The technique will allow the characteristics of each controlled sector to be obtained as well as the characteristics of the complete control system with its couplings through the reactor core. In addition, the developing use of frequency response testing of reactors makes necessary a knowledge of the spatial behaviour to be expected of a reactor under test. (author)

Nodewise analytical calculation of the transfer function

International Nuclear Information System (INIS)

Makai, Mihaly

1994-01-01

The space dependence of neutron noise has so far been mostly investigated in homogeneous core models. Application of core diagnostic methods to locate a malfunction requires however that the transfer function be calculated for real, inhomogeneous cores. A code suitable for such purpose must be able to handle complex arithmetic and delta-function source. Further requirements are analytical dependence in one spatial variable and fast execution. The present work describes the TIDE program written to fulfil the above requirements. The core is subdivided into homogeneous, square assemblies. An analytical solution is given, which is a generalisation of the inhomogeneous response matrix method. (author)

Vector Green's function algorithm for radiative transfer in plane-parallel atmosphere

International Nuclear Information System (INIS)

Qin Yi; Box, Michael A.

2006-01-01

Green's function is a widely used approach for boundary value problems. In problems related to radiative transfer, Green's function has been found to be useful in land, ocean and atmosphere remote sensing. It is also a key element in higher order perturbation theory. This paper presents an explicit expression of the Green's function, in terms of the source and radiation field variables, for a plane-parallel atmosphere with either vacuum boundaries or a reflecting (BRDF) surface. Full polarization state is considered but the algorithm has been developed in such way that it can be easily reduced to solve scalar radiative transfer problems, which makes it possible to implement a single set of code for computing both the scalar and the vector Green's function

Stressful Life Events in Children With Functional Defecation Disorders.

Science.gov (United States)

Philips, Elise M; Peeters, Babette; Teeuw, Arianne H; Leenders, Arnold G E; Boluyt, Nicole; Brilleslijper-Kater, Sonja N; Benninga, Marc A

2015-10-01

The aim of the study was to determine the prevalence of stressful life events including (sexual) abuse in children with functional defecation disorders by performing a systematic review. We searched MEDLINE, EMBASE, and PsycINFO for cohort, case-control and cross-sectional studies investigating the prevalence of stressful life events, including (sexual) abuse in children with functional defecation disorders. The search yielded 946 articles, of which 8 were included with data from 654 children with functional constipation and 1931 children with (constipation-associated) fecal incontinence (FI). Overall, children with functional defecation disorders had been significantly more exposed to stressful life events than healthy children, with prevalence rates ranging from 1.6% to 90.9%. Being bullied, being a relational victim, interruption of toilet training, punishment by parents during toilet training, and hospitalization were significantly related to FI, whereas separation from the best friend, failure in an examination, severe illness in a close family member, loss of job by a parent, frequent punishment, and living in a war-affected area were significantly related to constipation. Only 1 study measured the prevalence of child abuse, which reported a significantly higher prevalence of child (sexual) abuse in children with FI compared with controls. The prevalence of stressful life events, including (sexual) abuse is significantly higher in children with functional defecation disorders compared with healthy children. To gain more insight into the true prevalence of child (sexual) abuse in children with functional defecation disorders, more studies are clearly needed.

Hadronic wave functions and high momentum transfer interactions in quantum chromodynamics

International Nuclear Information System (INIS)

Brodsky, S.J.; Huang, T.; Lepage, G.P.

1983-01-01

This chapter emphasizes the utility of a Fock state representation of the meson and baryon wave functions as a means not only to parametrize the effects of bound state dynamics in QCD phenomena, but also to interrelate exclusive, inclusive, and higher twist processes. Discusses hadronic wave functions in QCD, measures of hadronic wave functions (form factors of composite systems, form factors of mesons, the meson distribution amplitude); large momentum transfer exclusive processes (two-photon processes); deep inelastic lepton scattering; and the phenomenology of hadronic wave functions (measures of hadron wave functions, constraints on the pion and proton valence wave function, quark jet diffraction excitation, the ''unveiling'' of the hadronic wave function and intrinsic charm). Finds that the testing ground of perturbative QCD where rigorous, definitive tests of the theory can be made can now be extended throughout a large domain of large momentum transfer exclusive and inclusive lepton, photon, and hadron reactions

Restoration of hippocampal growth hormone reverses stress-induced hippocampal impairment

Directory of Open Access Journals (Sweden)

Caitlin M. Vander Weele

2013-06-01

Full Text Available Though growth hormone (GH is synthesized by hippocampal neurons, where its expression is influenced by stress exposure, its function is poorly characterized. Here, we show that a regimen of chronic stress that impairs hippocampal function in rats also leads to a profound decrease in hippocampal GH levels. Restoration of hippocampal GH in the dorsal hippocampus via viral-mediated gene transfer completely reversed stress-related impairment of two hippocampus-dependent behavioral tasks, auditory trace fear conditioning and contextual fear conditioning, without affecting hippocampal function in unstressed control rats. GH overexpression reversed stress-induced decrements in both fear acquisition and long-term fear memory. These results suggest that loss of hippocampal GH contributes to hippocampal dysfunction following prolonged stress and demonstrate that restoring hippocampal GH levels following stress can promote stress resilience.

Causal transfer function analysis to describe closed loop interactions between cardiovascular and cardiorespiratory variability signals.

Science.gov (United States)

Faes, L; Porta, A; Cucino, R; Cerutti, S; Antolini, R; Nollo, G

2004-06-01

Although the concept of transfer function is intrinsically related to an input-output relationship, the traditional and widely used estimation method merges both feedback and feedforward interactions between the two analyzed signals. This limitation may endanger the reliability of transfer function analysis in biological systems characterized by closed loop interactions. In this study, a method for estimating the transfer function between closed loop interacting signals was proposed and validated in the field of cardiovascular and cardiorespiratory variability. The two analyzed signals x and y were described by a bivariate autoregressive model, and the causal transfer function from x to y was estimated after imposing causality by setting to zero the model coefficients representative of the reverse effects from y to x. The method was tested in simulations reproducing linear open and closed loop interactions, showing a better adherence of the causal transfer function to the theoretical curves with respect to the traditional approach in presence of non-negligible reverse effects. It was then applied in ten healthy young subjects to characterize the transfer functions from respiration to heart period (RR interval) and to systolic arterial pressure (SAP), and from SAP to RR interval. In the first two cases, the causal and non-causal transfer function estimates were comparable, indicating that respiration, acting as exogenous signal, sets an open loop relationship upon SAP and RR interval. On the contrary, causal and traditional transfer functions from SAP to RR were significantly different, suggesting the presence of a considerable influence on the opposite causal direction. Thus, the proposed causal approach seems to be appropriate for the estimation of parameters, like the gain and the phase lag from SAP to RR interval, which have a large clinical and physiological relevance.

An algebraic stress/flux model for two-phase turbulent flow

International Nuclear Information System (INIS)

Kumar, R.

1995-12-01

An algebraic stress model (ASM) for turbulent Reynolds stress and a flux model for turbulent heat flux are proposed for two-phase bubbly and slug flows. These mathematical models are derived from the two-phase transport equations for Reynolds stress and turbulent heat flux, and provide C μ , a turbulent constant which defines the level of eddy viscosity, as a function of the interfacial terms. These models also include the effect of heat transfer. When the interfacial drag terms and the interfacial momentum transfer terms are absent, the model reduces to a single-phase model used in the literature

The Use of the Self-Standing Turning Transfer Device to Perform Bed-To-Chair Transfers Reduces Physical Stress among Caregivers of Older Patients in a Middle-Income Developing Country.

Science.gov (United States)

Goh, Choon Hian; Muslimah Y; Ng, Siew-Cheok; Subramanian, Pathmawathi; Tan, Maw Pin

2014-01-01

Manual transfer of elderly patients remains commonplace in many developing countries because the use of lifting equipment, such as hoists, is often considered unaffordable luxuries. The aim of this study was, therefore, to evaluate the usage and potential benefits of a low-cost, mechanical turning transfer device among elderly patients and their caregivers on a geriatric ward in a developing country in South East Asia. Fifty-six inpatients, aged 66-92 years, on a geriatric ward, and their caregivers were recruited. Participants were asked to transfer from bed-to-chair transfer with manual assistance, and the task was repeated using the Self-standing Turning Transfer Device (STurDi). The time taken to perform manual transfers and STurDi-assisted transfers was recorded. Physical strain was assessed using the perceived physical stress-rating tool for caregivers with and without the use of the device. User satisfaction was evaluated using the usefulness, satisfaction, and ease of use questionnaire. There was a significant reduction in transfer-time with manual transfers compared to STurDi-assisted transfers [mean (SD) = 48.39 (13.98) vs. 36.23 (10.96); p ≤ 0.001]. The physical stress rating was significantly lower in STurDi-aided transfers compared to manual transfers, shoulder [median (interquartile range) = 0 (1) vs. 4 (3); p = 0.001], upper back [0 (0) vs. 5 (4); p = 0.001], lower back [0 (1) vs. 5 (3), p = 0.001], whole body [1 (2) vs. 4 (3), p = 0.001], and knee [0 (1) vs. 1 (4), p = 0.001]. In addition, majority of patients and caregivers definitely or strongly agreed that the device was useful, saved time, and was easy to use. We have therefore demonstrated in a setting where manual handling was commonly performed that a low-cost mechanical transfer device reduced caregiver strain and was well received by older patients and caregivers.

Nuclear response functions at large energy and momentum transfer

International Nuclear Information System (INIS)

Bertozzi, W.; Moniz, E.J.; Lourie, R.W.

1991-01-01

Quasifree nucleon processes are expected to dominate the nuclear electromagnetic response function for large energy and momentum transfers, i.e., for energy transfers large compared with nuclear single particle energies and momentum transfers large compared with typical nuclear momenta. Despite the evident success of the quasifree picture in providing the basic frame work for discussing and understanding the large energy, large momentum nuclear response, the limits of this picture have also become quite clear. In this article a selected set of inclusive and coincidence data are presented in order to define the limits of the quasifree picture more quantitatively. Specific dynamical mechanisms thought to be important in going beyond the quasifree picture are discussed as well. 75 refs, 37 figs

Measurement of multi-bunch transfer functions using time-domain data and Fourier analysis

International Nuclear Information System (INIS)

Hindi, H.; Sapozhnikov, L.; Fox, J.; Prabhakar, S.; Oxoby, G.; Linscott, I.; Drago, A.

1993-12-01

Multi-bunch transfer functions are principal ingredients in understanding both the behavior of high-current storage rings as well as control of their instabilities. The measurement of transfer functions on a bunch-by-bunch basis is particularly important in the design of active feedback systems. Traditional methods of network analysis that work well in the single bunch case become difficult to implement for many bunches. We have developed a method for obtaining empirical estimates of the multi-bunch longitudinal transfer functions from the time-domain measurements of the bunches' phase oscillations. This method involves recording the response of the bunch of interest to a white-noise excitation. The transfer function can then be computed as the ratio of the fast Fourier transforms (FFTs) of the response and excitation sequences, averaged over several excitations. The calculation is performed off-line on bunch-phase data and is well-suited to the multi-bunch case. A description of this method and an analysis of its performance is presented with results obtained using the longitudinal quick prototype feedback system developed at SLAC

A parametric transfer function methodology for analyzing reactive transport in nonuniform flow.

Science.gov (United States)

Luo, Jian; Cirpka, Olaf A; Fienen, Michael N; Wu, Wei-min; Mehlhorn, Tonia L; Carley, Jack; Jardine, Philip M; Criddle, Craig S; Kitanidis, Peter K

2006-02-01

We analyze reactive transport during in-situ bioremediation in a nonuniform flow field, involving multiple extraction and injection wells, by the method of transfer functions. Gamma distributions are used as parametric models of the transfer functions. Apparent parameters of classical transport models may be estimated from those of the gamma distributions by matching temporal moments. We demonstrate the method by application to measured data taken at a field experiment on bioremediation conducted in a multiple-well system in Oak Ridge, TN. Breakthrough curves (BTCs) of a conservative tracer (bromide) and a reactive compound (ethanol) are measured at multi-level sampling (MLS) wells and in extraction wells. The BTCs of both compounds are jointly analyzed to estimate the first-order degradation rate of ethanol. To quantify the tracer loss, we compare the approaches of using a scaling factor and a first-order decay term. Results show that by including a scaling factor both gamma distributions and inverse-Gaussian distributions (transfer functions according to the advection-dispersion equation) are suitable to approximate the transfer functions and estimate the reactive rate coefficients for both MLS and extraction wells. However, using a first-order decay term for tracer loss fails to describe the BTCs at the extraction well, which is affected by the nonuniform distribution of travel paths.

The Mid-Term Changes of Pulmonary Function Tests After Phrenic Nerve Transfer.

Science.gov (United States)

Yavari, Masoud; Hassanpour, Seyed Esmail; Khodayari, Mohammad

2016-03-01

In the restoration of elbow flexion, the phrenic nerve has proven to be a good donor, but considering the role of the phrenic nerve in respiratory function, we cannot disregard the potential dangers of this method. In the current study, we reviewed the results of pulmonary function tests (PFT) in four patients who underwent phrenic nerve transfer. We reviewed the results of serial spirometry tests, which were performed before and after phrenic nerve transfer surgery. All patients regained Biceps power to M3 strength or above. None of our patients experienced pulmonary problems or respiratory complaints, but a significant reduction of spirometric parameters occurred after surgery. This study highlights the close link between the role of the phrenic nerve and pulmonary function, such that the use of this nerve as a transfer donor leads to spirometric impairments.

A novel hybrid stress-function finite element method immune to severe mesh distortion

International Nuclear Information System (INIS)

Cen Song; Zhou Mingjue; Fu Xiangrong

2010-01-01

This paper introduces a hybrid stress-function finite element method proposed recently for developing 2D finite element models immune to element shapes. Deferent from the first version of the hybrid-stress element constructed by Pian, the stress function φ of 2D elastic or fracture problem is regarded as the functional variable of the complementary energy functional. Then, the basic analytical solutions of φ are taken as the trial functions for finite element models, and meanwhile, the corresponding unknown stress-function constants are introduced. By using the principle of minimum complementary energy, these unknown stress-function constants can be expressed in terms of the displacements along element edges. Finally, the complementary energy functional can be rewritten in terms of element nodal displacement vector, and thus, the element stiffness matrix of such hybrid-function element can be obtained. As examples, two (8- and 12-node) quadrilateral plane elements and an arbitrary polygonal crack element are constructed by employing different basic analytical solutions of different stress functions. Numerical results show that, the 8- and 12-node plane models can produce the exact solutions for pure bending and linear bending problems, respectively, even the element shape degenerates into triangle and concave quadrangle; and the crack element can also predict accurate results with very low computational cost in analysis of stress-singularity problems.

Automatic transfer function design for medical visualization using visibility distributions and projective color mapping.

Science.gov (United States)

Cai, Lile; Tay, Wei-Liang; Nguyen, Binh P; Chui, Chee-Kong; Ong, Sim-Heng

2013-01-01

Transfer functions play a key role in volume rendering of medical data, but transfer function manipulation is unintuitive and can be time-consuming; achieving an optimal visualization of patient anatomy or pathology is difficult. To overcome this problem, we present a system for automatic transfer function design based on visibility distribution and projective color mapping. Instead of assigning opacity directly based on voxel intensity and gradient magnitude, the opacity transfer function is automatically derived by matching the observed visibility distribution to a target visibility distribution. An automatic color assignment scheme based on projective mapping is proposed to assign colors that allow for the visual discrimination of different structures, while also reflecting the degree of similarity between them. When our method was tested on several medical volumetric datasets, the key structures within the volume were clearly visualized with minimal user intervention. Copyright © 2013 Elsevier Ltd. All rights reserved.

Psychological stress-relieving effects of chewing - Relationship between masticatory function-related factors and stress-relieving effects.

Science.gov (United States)

Tasaka, Akinori; Kikuchi, Manaki; Nakanishi, Kousuke; Ueda, Takayuki; Yamashita, Shuichiro; Sakurai, Kaoru

2018-01-01

The objective of the present study was to investigate the relationship between masticatory function-related factors (masticatory performance, occlusal contact area, maximum bite force, number of chewing strokes, and muscle activity) and the stress-relieving effects of chewing. A total of 28 healthy male subjects were instructed to rest or chew for 10min after 30min of stress loading with arithmetic calculations. Their stress state was assessed by measuring salivary cortisol levels. Saliva was collected at three time points: before stress loading, immediately after stress loading, and 10min after stress loading. Compared to resting, chewing produced a significantly greater reduction in the rate of change in salivary cortisol levels 10min after stress loading. A negative correlation was observed between the rate of decrease in salivary cortisol levels and the number of chewing strokes. No significant correlation was observed between the rate of decrease in salivary cortisol levels and other measurement items. In healthy dentulous people, the number of chewing strokes has been shown to be a masticatory function-related factor that affects stress relief from chewing, suggesting the possibility that more appropriate chewing would produce a greater effect psychological stress relief. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Time variation of the electromagnetic transfer function of the earth estimated by using wavelet transform.

Science.gov (United States)

Suto, Noriko; Harada, Makoto; Izutsu, Jun; Nagao, Toshiyasu

2006-07-01

In order to accurately estimate the geomagnetic transfer functions in the area of the volcano Mt. Iwate (IWT), we applied the interstation transfer function (ISTF) method to the three-component geomagnetic field data observed at Mt. Iwate station (IWT), using the Kakioka Magnetic Observatory, JMA (KAK) as remote reference station. Instead of the conventional Fourier transform, in which temporary transient noises badly degrade the accuracy of long term properties, continuous wavelet transform has been used. The accuracy of the results was as high as that of robust estimations of transfer functions obtained by the Fourier transform method. This would provide us with possibilities for routinely monitoring the transfer functions, without sophisticated statistical procedures, to detect changes in the underground electrical conductivity structure.

Surface shear stress dependence of gas transfer velocity parameterizations using DNS

Science.gov (United States)

Fredriksson, S. T.; Arneborg, L.; Nilsson, H.; Handler, R. A.

2016-10-01

Air-water gas-exchange is studied in direct numerical simulations (DNS) of free-surface flows driven by natural convection and weak winds. The wind is modeled as a constant surface-shear-stress and the gas-transfer is modeled via a passive scalar. The simulations are characterized via a Richardson number Ri=Bν/u*4 where B, ν, and u* are the buoyancy flux, kinematic viscosity, and friction velocity respectively. The simulations comprise 0Ric or kg=AShearu*Sc-n, Ri

Schottky Noise and Beam Transfer Functions

Energy Technology Data Exchange (ETDEWEB)

Blaskiewicz M.; Blaskiewicz M.

2016-12-01

Beam transfer functions (BTF)s encapsulate the stability properties of charged particle beams. In general one excites the beam with a sinusoidal signal and measures the amplitude and phase of the beam response. Most systems are very nearly linear and one can use various Fourier techniques to reduce the number of measurements and/or simulations needed to fully characterize the response. Schottky noise is associated with the finite number of particles in the beam. This signal is always present. Since the Schottky current drives wakefields, the measured Schottky signal is influenced by parasitic impedances.

Transient Stress Intensity Factors of Functionally Graded Hollow Cylinders with Internal Circumferential Cracks

Directory of Open Access Journals (Sweden)

Iman Eshraghi

Full Text Available Abstract In this paper, transient thermomechanical stress intensity factors for functionally graded cylinders with complete internal circumferential cracks are obtained using the weight function method. The finite difference method is used to calculate the time dependent temperature distribution and thermal stresses along the cylinder thickness. Furthermore, finite element analysis is performed to determine the weight function coefficients and to investigate the accuracy of the predicted stress intensity factors from the weight functions. Variation of the stress intensity factors with time and effects of the material gradation on the results are investigated, as well. It is shown that the proposed technique can be used to accurately predict transient thermomechanical stress intensity factors for functionally graded cylinders with arbitrary material gradation.

A discrete stress-strength interference model based on universal generating function

International Nuclear Information System (INIS)

An Zongwen; Huang Hongzhong; Liu Yu

2008-01-01

Continuous stress-strength interference (SSI) model regards stress and strength as continuous random variables with known probability density function. This, to some extent, results in a limitation of its application. In this paper, stress and strength are treated as discrete random variables, and a discrete SSI model is presented by using the universal generating function (UGF) method. Finally, case studies demonstrate the validity of the discrete model in a variety of circumstances, in which stress and strength can be represented by continuous random variables, discrete random variables, or two groups of experimental data

Estimation of acoustic resonances for room transfer function equalization

DEFF Research Database (Denmark)

Gil-Cacho, Pepe; van Waterschoot, Toon; Moonen, Marc

2010-01-01

Strong acoustic resonances create long room impulse responses (RIRs) which may harm the speech transmission in an acoustic space and hence reduce speech intelligibility. Equalization is performed by cancelling the main acoustic resonances common to multiple room transfer functions (RTFs), i...

Autobiographical memory functions and posttraumatic stress symptoms across adulthood

DEFF Research Database (Denmark)

del Palacio Gonzalez, Adriana; Watson, Lynn Ann; Berntsen, Dorthe

2018-01-01

. In this study, we examined the unique relationship between autobiographical memory functions and posttraumatic stress symptoms (PTSS) and whether such relationships varied with age across adulthood. A representative sample of 1040 adult Danes (20–70 years old) reported the frequency with which they recall......Previous research has documented robust individual differences in the functions served by autobiographical memories, and shown that different autobiographical memory functions are related to both positive and negative indicators of psychological well-being, and that their frequency varies with age...... autobiographical memories for different purposes as well as their level of posttraumatic stress disorder (PTSD) symptoms. Higher reflective and ruminative functions, as well as lower social function, predicted higher levels of PTSS. There were no moderating effects of age. The results suggest that although...

A nuclide transfer model for barriers of the seabed repository using response function

International Nuclear Information System (INIS)

Lee, Youn Myoung; Kang, Chul Hyung; Hahn, Pil Soo

1996-01-01

A nuclide transfer by utilizing mass transfer coefficient and barrier response function defined for each barrier is proposed, by which the final nuclide transfer rate into the sea water can be evaluated. When simple and immediate quantification of the nuclide release is necessary in the conservative aspect, using this kind of approach may be advantageous since each layered barrier can be treated separately from other media in series in the repository system, making it possible to apply separate solutions in succession to other various media. Although one disadvantage is that while flux continuity can be maintained at the interface by using the exit nuclide flux from the first medium as the source flux for the next one, there may be no guarantee for concentration continuity, this problem could be eliminated assuming that there is no boundary resistance to mass transfer across the interface. Mass transfer coefficient can be determined by the assumption that the nuclide concentration gradient at the interface between adjacent barriers remains constant and barrier response function is obtained from an analytical expression for nuclide flow rate out of each barrier in response to a unit impulse into the barrier multiplied by mass transfer coefficient. Total time-dependent nuclide transfer rate from the barrier can then be obtained by convoluting the response function for the barrier with a previously calculated set of time-varying input of nuclide flow rate for the previous barrier. 18 refs., 5 figs. (author)

Integration of Heat Transfer, Stress, and Particle Trajectory Simulation

Energy Technology Data Exchange (ETDEWEB)

Thuc Bui; Michael Read; Lawrence ives

2012-05-17

Calabazas Creek Research, Inc. developed and currently markets Beam Optics Analyzer (BOA) in the United States and abroad. BOA is a 3D, charged particle optics code that solves the electric and magnetic fields with and without the presence of particles. It includes automatic and adaptive meshing to resolve spatial scales ranging from a few millimeters to meters. It is fully integrated with CAD packages, such as SolidWorks, allowing seamless geometry updates. The code includes iterative procedures for optimization, including a fully functional, graphical user interface. Recently, time dependent, particle in cell capability was added, pushing particles synchronically under quasistatic electromagnetic fields to obtain particle bunching under RF conditions. A heat transfer solver was added during this Phase I program. Completed tasks include: (1) Added a 3D finite element heat transfer solver with adaptivity; (2) Determined the accuracy of the linear heat transfer field solver to provide the basis for development of higher order solvers in Phase II; (3) Provided more accurate and smoother power density fields; and (4) Defined the geometry using the same CAD model, while maintaining different meshes, and interfacing the power density field between the particle simulator and heat transfer solvers. These objectives were achieved using modern programming techniques and algorithms. All programming was in C++ and parallelization in OpenMP, utilizing state-of-the-art multi-core technology. Both x86 and x64 versions are supported. The GUI design and implementation used Microsoft Foundation Class.

Seismic analysis with FEM for fuel transfer system of PWR nuclear power plant

International Nuclear Information System (INIS)

Jia Xiaofeng; Liu Pengliang; Bi Xiangjun; Ji Shunying

2012-01-01

In the PWR nuclear power plant, the function of the fuel transfer system (FTS) is to transfer the fuel assembly between the reactor building and the fuel building. The seismic analysis of the transfer system structure should be carried out to ensure the safety under OBE and SSE. Therefore, the ANASYS 12.0 software is adopted to construct the finite element analysis model for the fuel transfer system in a million kilowatt nuclear power plant. For the various configurations of FTS in the operating process, the stresses of the main structures, such as the transfer tube, fuel assembly container, fuel conveyor car, lifting frame in the reactor building, lifting frame in the fuel building, support and guide structure of conveyor car and the lifting frame in both buildings, are computed. The stresses are combined with the method of square root of square sum (SRSS) and assessed under various seismic conditions based on RCCM code, the results of the assessment satisfy the code. The results show that the stresses of the fuel transfer system structure meet the strength requirement, meanwhile, it can withstand the earthquake well. (authors)

The Role of Stress Exposure and Family Functioning in Internalizing Outcomes of Urban Families.

Science.gov (United States)

Sheidow, Ashli J; Henry, David B; Tolan, Patrick H; Strachan, Martha K

2014-11-01

Although research suggests that stress exposure and family functioning are associated with internalizing problems in adolescents and caregivers, surprisingly few studies have investigated the mechanisms that underlie this association. To determine whether family functioning buffers the development of internalizing problems in stress-exposed families, we assessed the relation between stress exposure, family functioning, and internalizing symptoms among a large sample of inner-city male youth and their caregivers living in poverty across five waves of data collection. We hypothesized that stress exposure and family functioning would predict development of subsequent youth and caregiver internalizing problems and that family functioning would moderate this relation, with higher functioning families demonstrating greater resiliency to stress exposure. We used a longitudinal, prospective design to evaluate whether family functioning (assessed at waves one through four) activated or buffered the effects of stress exposure (assessed at wave one) on subsequent internalizing symptoms (assessed at waves four and five). Stress from Developmental Transitions and family functioning were significant predictors of depressive symptoms and anxiety in youth; however, family functioning did not moderate the relation. Family functioning mediated the relation between stress from Daily Hassles and internalizing outcomes suggesting that poor parenting practices, low structure, and low emotional cohesion activate depression and anxiety in youth exposed to chronic and frequent everyday stressors. Surprisingly, only family functioning predicted depressive symptoms in caregivers. Results validate the use of a comprehensive, multi-informant assessment of stress when investigating internalizing outcomes in youth and support using family-based interventions in the treatment and prevention of internalizing.

The stress-buffering effects of functional social support on ambulatory blood pressure.

Science.gov (United States)

Bowen, Kimberly S; Uchino, Bert N; Birmingham, Wendy; Carlisle, McKenzie; Smith, Timothy W; Light, Kathleen C

2014-11-01

Social support is a reliable predictor of cardiovascular health. According to the buffering hypothesis, stress is 1 mechanism by which support is able to affect physiological processes. However, most of the experimental evidence for the hypothesis comes from laboratory studies. Ambulatory blood pressure (ABP) protocols examine participants in their natural environment, where they are more likely to encounter personally relevant real-world stressors. Furthermore, prior work shows that examining support by its specific functional components reveals additional independent links to health. The current study aimed to examine the stress-buffering effects of functional social support on ABP. One hundred eighty-eight participants completed a 1-day ABP assessment along with measures of functional social support and both global perceived stress and momentary stress at time of reading. RESULTS indicated main effects for both stress measures. Global support, emotional, tangible, and informational support only moderated the effects of momentary stress, but not global stress, in predicting ABP. Informational support was the most consistent stress-buffering predictor of ABP, predicting both ambulatory systolic and diastolic blood pressure. The predicted values in ABP for informational support achieved health-relevant differences, emphasizing the value of examining functional support beyond global support alone. PsycINFO Database Record (c) 2014 APA, all rights reserved.

A hierarchical stress release model for synthetic seismicity

Science.gov (United States)

Bebbington, Mark

1997-06-01

We construct a stochastic dynamic model for synthetic seismicity involving stochastic stress input, release, and transfer in an environment of heterogeneous strength and interacting segments. The model is not fault-specific, having a number of adjustable parameters with physical interpretation, namely, stress relaxation, stress transfer, stress dissipation, segment structure, strength, and strength heterogeneity, which affect the seismicity in various ways. Local parameters are chosen to be consistent with large historical events, other parameters to reproduce bulk seismicity statistics for the fault as a whole. The one-dimensional fault is divided into a number of segments, each comprising a varying number of nodes. Stress input occurs at each node in a simple random process, representing the slow buildup due to tectonic plate movements. Events are initiated, subject to a stochastic hazard function, when the stress on a node exceeds the local strength. An event begins with the transfer of excess stress to neighboring nodes, which may in turn transfer their excess stress to the next neighbor. If the event grows to include the entire segment, then most of the stress on the segment is transferred to neighboring segments (or dissipated) in a characteristic event. These large events may themselves spread to other segments. We use the Middle America Trench to demonstrate that this model, using simple stochastic stress input and triggering mechanisms, can produce behavior consistent with the historical record over five units of magnitude. We also investigate the effects of perturbing various parameters in order to show how the model might be tailored to a specific fault structure. The strength of the model lies in this ability to reproduce the behavior of a general linear fault system through the choice of a relatively small number of parameters. It remains to develop a procedure for estimating the internal state of the model from the historical observations in order to

Effects of polymer stresses on analogy between momentum and heat transfer in drag-reduced turbulent channel flow

Science.gov (United States)

Kim, Kyoungyoun; Sureshkumar, Radhakrishna

2018-03-01

The effects of polymer stresses on the analogy between momentum and heat transfer are examined by using a direct numerical simulation (DNS) of viscoelastic turbulent channel flows using a constant heat flux boundary condition. The Reynolds number based on the friction velocity and channel half height is 125, and the Prandtl number is 5. The polymer stress is modeled using the finitely extensible nonlinear elastic-Peterlin constitutive model, and low (15%), intermediate (34%), and high drag reduction (DR) (52%) cases are examined. The Colburn analogy is found to be inapplicable for viscoelastic turbulent flows, suggesting dissimilarity between the momentum and heat transfer at the macroscopic coefficient level. The mean temperature profile also shows behaviour different from the mean velocity profile in drag-reduced flows. In contrast to the dissimilarity in the mean profiles, the turbulent Prandtl number Prt predicted by the DNS is near unity. This implies that turbulent heat transfer is still analogous to turbulent momentum transfer in drag-reduced flows, as in Newtonian flow. An increase in DR is accompanied by an increase in the correlation coefficient ρuθ between the instantaneous fluctuations in the streamwise velocity u and temperature θ. The correlation coefficient between u' and wall-normal velocity fluctuations v', ρ-u v, exhibits a profile similar to that of ρ-θ v in drag-reduced and Newtonian flows. Finally, the budget analysis of the transport equations of turbulent heat flux shows a strong similarity between the turbulent momentum and heat transfer, which is consistent with the predictions of Prt near unity.

MLP based LOGSIG transfer function for solar generation monitoring

Science.gov (United States)

Hashim, Fakroul Ridzuan; Din, Muhammad Faiz Md; Ahmad, Shahril; Arif, Farah Khairunnisa; Rizman, Zairi Ismael

2018-02-01

Solar panel is one of the renewable energy that can reduce the environmental pollution and have a wide potential of application. The exact solar prediction model will give a big impact on the management of solar power plants and the design of solar energy systems. This paper attempts to use Multilayer Perceptron (MLP) neural network based transfer function. The MLP network can be used to calculate the temperature module (TM) in Malaysia. This can be done by simulating the collected data of four weather variables which are the ambient temperature (TA), local wind speed (VW), solar radiation flux (GT) and the relative humidity (RH) as the input into the neural network. The transfer function will be applied to the 14 types of training. Finally, an equation from the best training algorithm will be deduced to calculate the temperature module based on the input of weather variables in Malaysia.

Modified Displacement Transfer Functions for Deformed Shape Predictions of Slender Curved Structures with Varying Curvatives

Science.gov (United States)

Ko, William L.; Fleischer, Van Tran

2014-01-01

To eliminate the need to use finite-element modeling for structure shape predictions, a new method was invented. This method is to use the Displacement Transfer Functions to transform the measured surface strains into deflections for mapping out overall structural deformed shapes. The Displacement Transfer Functions are expressed in terms of rectilinearly distributed surface strains, and contain no material properties. This report is to apply the patented method to the shape predictions of non-symmetrically loaded slender curved structures with different curvatures up to a full circle. Because the measured surface strains are not available, finite-element analysis had to be used to analytically generate the surface strains. Previously formulated straight-beam Displacement Transfer Functions were modified by introducing the curvature-effect correction terms. Through single-point or dual-point collocations with finite-elementgenerated deflection curves, functional forms of the curvature-effect correction terms were empirically established. The resulting modified Displacement Transfer Functions can then provide quite accurate shape predictions. Also, the uniform straight-beam Displacement Transfer Function was applied to the shape predictions of a section-cut of a generic capsule (GC) outer curved sandwich wall. The resulting GC shape predictions are quite accurate in partial regions where the radius of curvature does not change sharply.

Early transfer of mated females into the maternity unit reduces stress and increases maternal care in farm mink

DEFF Research Database (Denmark)

Malmkvist, Jens; Palme, Rupert

2015-01-01

Mated mammals on farms are typically transferred to another housing environment prior to delivery. We investigated whether the timing of this transfer – EARLY (Day −36), INTERMEDIATE (Day −18), or LATE (Day −3) relative to the expected day of birth (Day 0) – affects maternal stress, maternal care...... sized groups (n = 60): (i) ‘EARLY’, transfer to maternity unit immediately after the end of the mating period, March 23; (ii) ‘INTERMEDIATE’, transfer in the middle of the period, April 10; (iii) ‘LATE’, transfer late in the pregnancy period, April 25. Data collection included weekly determination...... of faecal cortisol metabolites (FCM) and evaluation of maternal care: nest building, in-nest temperature, plus kit-retrieval behaviour, kit mortality and growth day 0–7 postpartum. We document that mated mink females build and maintain a nest at least 1 month prior to delivery when transferred...

Effects of the Cognitive-Behavioral Therapy for Stress Management on Executive Function Components.

Science.gov (United States)

Santos-Ruiz, Ana; Robles-Ortega, Humbelina; Pérez-García, Miguel; Peralta-Ramírez, María Isabel

2017-02-13

This study aims to determine whether it is possible to modify executive function in stressed individuals by means of cognitive-behavioral therapy for stress management. Thirty-one people with high levels of perceived stress were recruited into the study (treatment group = 18; wait-list group = 13). The treatment group received 14 weeks of stress management program. Psychological and executive function variables were evaluated in both groups pre and post-intervention. The treatment group showed improved psychological variables of perceived stress (t = 5.492; p = .001), vulnerability to stress (t = 4.061; p = .001) and superstitious thinking (t = 2.961; p = .009). Likewise, the results showed statistically significant differences in personality variables related to executive function, positive urgency (t = 3.585; p = .002) and sensitivity to reward (t = -2.201; p = .042), which improved after the therapy. These variables showed a moderate to high effect size (oscillates between 1.30 for perceived stress and .566 for sensitivity to reward). The cognitive-behavioral therapy for stress management may be an appropriate strategy for improving personality construct components related to executive function, however effects of the therapy are not showed on performance on the tests of executive function applied, as presented studies previous.

Quality evaluation of mammography systems: identification of the best region by the transfer function method

International Nuclear Information System (INIS)

Schiabel, H.; Frere, A.F.

1992-01-01

The evaluation of mammography systems behaviour, using the conventional analysis method of transfer function is discussed. An investigation for evaluating the behaviour of modulation transfer function on several direction of orifices in the radiation field is also presented. (C.G.C.)

In-Situ Neutron Diffraction Under Tensile Loading of Powder-in-Tube Cu/Nb$_{3}$Sn Composite Wires Effect of Reaction Heat Treatment on Texture, Internal Stress State and Load Transfer

CERN Document Server

Scheuerlein, C; Thilly, L

2007-01-01

The strain induced degradation of Nb$_{3}$Sn superconductors can hamper the performance of high field magnets. We report elastic strain measurements in the different phases of entire non-heat treated and fully reacted Nb$_{3}$Sn composite strands as a function of uniaxial stress during in-situ deformation under neutron beam. After the reaction heat treatment the Cu matrix loses entirely its load carrying capability and the applied stress is transferred to the remaining Nb-Ta alloy and to the brittle (Nb-Ta)3Sn phase, which exhibits a preferential grain orientation parallel to the strand axis.

Analysis of space vehicle structures using the transfer-function concept

Science.gov (United States)

Heer, E.; Trubert, M. R.

1969-01-01

Analysis of large complex systems is accomplished by dividing it into suitable subsystems and determining the individual dynamical and vibrational responses. Frequency transfer functions then determine the vibrational response of the whole system.

Oversampling ad converters with improved signal transfer functions

CERN Document Server

Pandita, Bupesh

2011-01-01

This book describes techniques for designing complex, discrete-time I""IGBP ADCs with signal-transfer functions that significantly filter interfering signals. The book provides an understanding of theory, issues, and implementation of discrete complex I""IGBP ADCs. The concepts developed in each chapter are further explained by applying them to a target application of I""IGBP ADCs in DTV receivers.

Stress tolerances of nullmutants of function-unknown genes encoding menadione stress-responsive proteins in Aspergillus nidulans.

Science.gov (United States)

Leiter, Éva; Bálint, Mihály; Miskei, Márton; Orosz, Erzsébet; Szabó, Zsuzsa; Pócsi, István

2016-07-01

A group of menadione stress-responsive function-unkown genes of Aspergillus nidulans (Locus IDs ANID_03987.1, ANID_06058.1, ANID_10219.1, and ANID_10260.1) was deleted and phenotypically characterized. Importantly, comparative and phylogenetic analyses of the tested A. nidulans genes and their orthologs shed light only on the presence of a TANGO2 domain with NRDE protein motif in the translated ANID_06058.1 gene but did not reveal any recognizable protein-encoding domains in other protein sequences. The gene deletion strains were subjected to oxidative, osmotic, and metal ion stress and, surprisingly, only the ΔANID_10219.1 mutant showed an increased sensitivity to 0.12 mmol l(-1) menadione sodium bisulfite. The gene deletions affected the stress sensitivities (tolerances) irregularly, for example, some strains grew more slowly when exposed to various oxidants and/or osmotic stress generating agents, meanwhile the ΔANID_10260.1 mutant possessed a wild-type tolerance to all stressors tested. Our results are in line with earlier studies demonstrating that the deletions of stress-responsive genes do not confer necessarily any stress-sensitivity phenotypes, which can be attributed to compensatory mechanisms based on other elements of the stress response system with overlapping functions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functional outcome of nerve transfer for restoration of shoulder and elbow function in upper brachial plexus injury

Directory of Open Access Journals (Sweden)

Faruquee Sajedur

2008-05-01

Full Text Available Abstract Background Purpose of this study was to evaluate the functional outcome of spinal accessory to suprascapular nerve transfer (XI-SSN done for restoration of shoulder function and partial transfer of ulnar nerve to the motor branch to the biceps muscle for the recovery of elbow flexion (Oberlin transfer. Methods This is a prospective study involving 15 consecutive cases of upper plexus injury seen between January 2004 and December 2005. The average age of patients was 35.6 yrs (15–52 yrs. The injury-surgery interval was between 2–6 months. All underwent XI-SSN and Oberlin nerve transfer. The coaptation was done close to the biceps muscle to ensure early recovery. The average follow up was 15 months (range 12–36 months. The functional outcome was assessed by measuring range of movements and also on the grading scale proposed by Narakas for shoulder function and Waikakul for elbow function. Results Good/Excellent results were seen in 13/15 patients with respect to elbow function and 8/15 for shoulder function. The time required for the first sign of clinical reinnervation of biceps was 3 months 9 days (range 1 month 25 days to 4 months and for the recovery of antigravity elbow flexion was 5 months (range 3 1/2 months to 8 months. 13 had M4 and two M3 power. On evaluating shoulder function 8/15 regained active abduction, five had M3 and three M4 shoulder abduction. The average range of abduction in these eight patients was 66 degrees (range 45–90. Eight had recovered active external rotation, average 44 degrees (range 15–95. The motor recovery of external rotation was M3 in 5 and M4 in 3. 7/15 had no active abduction/external rotation, but they felt that their shoulder was more stable. Comparable results were observed in both below and above 40 age groups and those with injury to surgery interval less than 3 or 3–6 months. Conclusion Transfer of ulnar nerve fascicle to the motor branch of biceps close to the muscle consistently

Production of functional proteins: balance of shear stress and gravity

Science.gov (United States)

Goodwin, Thomas John (Inventor); Hammond, Timothy Grant (Inventor); Kaysen, James Howard (Inventor)

2011-01-01

A method for the production of functional proteins including hormones by renal cells in a three dimensional culturing process responsive to shear stress uses a rotating wall vessel. Natural mixture of renal cells expresses the enzyme 1-.alpha.-hydroxylase which can be used to generate the active form of vitamin D: 1,25-diOH vitamin D.sub.3. The fibroblast cultures and co-culture of renal cortical cells express the gene for erythropoietin and secrete erythropoietin into the culture supernatant. Other shear stress response genes are also modulated by shear stress, such as toxin receptors megalin and cubulin (gp280). Also provided is a method of treating an in-need individual with the functional proteins produced in a three dimensional co-culture process responsive to shear stress using a rotating wall vessel.

New transfer functions for probing 3-D mantle conductivity from ground and sea

DEFF Research Database (Denmark)

Püthe, C.; Kuvshinov, A.; Olsen, Nils

2014-01-01

The C-response is a conventional transfer function in global electromagnetic induction research and is classically determined from local observations of magnetic variations in the vertical and the horizontal components. Its estimation and interpretation rely on the assumptions that the source...... source. We investigate the variability of C-responses due to non-P10 contributions to the source. We show that this variability, which we denote as 'source effect' (as opposed to the well-known ocean effect), is significant and persists at all periods. If inverting estimated C-responses for mantle...... telecommunication cables to spherical harmonic coefficients in the same way as described above, one can define yet another array of transfer functions. In spite of the fact that the newly introduced transfer functions allow for a consistent treatment of a complex spatial structure of the source, the sparse...

Three-dimensional optical transfer functions in the aberration-corrected scanning transmission electron microscope.

Science.gov (United States)

Jones, L; Nellist, P D

2014-05-01

In the scanning transmission electron microscope, hardware aberration correctors can now correct for the positive spherical aberration of round electron lenses. These correctors make use of nonround optics such as hexapoles or octupoles, leading to the limiting aberrations often being of a nonround type. Here we explore the effect of a number of potential limiting aberrations on the imaging performance of the scanning transmission electron microscope through their resulting optical transfer functions. In particular, the response of the optical transfer function to changes in defocus are examined, given that this is the final aberration to be tuned just before image acquisition. The resulting three-dimensional optical transfer functions also allow an assessment of the performance of a system for focal-series experiments or optical sectioning applications. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Multidimensional Wave Field Signal Theory: Transfer Function Relationships

Directory of Open Access Journals (Sweden)

Natalie Baddour

2012-01-01

Full Text Available The transmission of information by propagating or diffusive waves is common to many fields of engineering and physics. Such physical phenomena are governed by a Helmholtz (real wavenumber or pseudo-Helmholtz (complex wavenumber equation. Since these equations are linear, it would be useful to be able to use tools from signal theory in solving related problems. The aim of this paper is to derive multidimensional input/output transfer function relationships in the spatial domain for these equations in order to permit such a signal theoretic approach to problem solving. This paper presents such transfer function relationships for the spatial (not Fourier domain within appropriate coordinate systems. It is shown that the relationships assume particularly simple and computationally useful forms once the appropriate curvilinear version of a multidimensional spatial Fourier transform is used. These results are shown for both real and complex wavenumbers. Fourier inversion of these formulas would have applications for tomographic problems in various modalities. In the case of real wavenumbers, these inversion formulas are presented in closed form, whereby an input can be calculated from a given or measured wavefield.

Latino parent acculturation stress: Longitudinal effects on family functioning and youth emotional and behavioral health.

Science.gov (United States)

Lorenzo-Blanco, Elma I; Meca, Alan; Unger, Jennifer B; Romero, Andrea; Gonzales-Backen, Melinda; Piña-Watson, Brandy; Cano, Miguel Ángel; Zamboanga, Byron L; Des Rosiers, Sabrina E; Soto, Daniel W; Villamar, Juan A; Lizzi, Karina M; Pattarroyo, Monica; Schwartz, Seth J

2016-12-01

Latino parents can experience acculturation stressors, and according to the Family Stress Model (FSM), parent stress can influence youth mental health and substance use by negatively affecting family functioning. To understand how acculturation stressors come together and unfold over time to influence youth mental health and substance use outcomes, the current study investigated the trajectory of a latent parent acculturation stress factor and its influence on youth mental health and substance use via parent-and youth-reported family functioning. Data came from a 6-wave, school-based survey with 302 recent (stress loaded onto a latent factor of acculturation stress at each of the first 4 time points. Earlier levels of and increases in parent acculturation stress predicted worse youth-reported family functioning. Additionally, earlier levels of parent acculturation stress predicted worse parent-reported family functioning and increases in parent acculturation stress predicted better parent-reported family functioning. While youth-reported positive family functioning predicted higher self-esteem, lower symptoms of depression, and lower aggressive and rule-breaking behavior in youth, parent-reported family positive functioning predicted lower youth alcohol and cigarette use. Findings highlight the need for Latino youth preventive interventions to target parent acculturation stress and family functioning. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Leaf sodium accumulation facilitates salt stress adaptation and preserves photosystem functionality in salt stressed Ocimum basilicum

NARCIS (Netherlands)

Mancarella, S.; Orsini, F.; Oosten, van M.J.; Sanoubar, R.; Stanghellini, C.; Kondo, S.; Gianquinto, G.; Maggio, A.

2016-01-01

In this study, plant growth, water relations, ABA levels, ion accumulation patterns and chlorophyll fluorescence were functionally linked to salt stress tolerance of two basil cultivars (Napoletano and Genovese) with different stress sensitivity levels. Plants were treated with salty water at 0,

A nonspecific Setaria italica lipid transfer protein gene plays a critical role under abiotic stress

Directory of Open Access Journals (Sweden)

Yanlin Pan

2016-11-01

Full Text Available Lipid transfer proteins (LTPs are a class of cysteine-rich soluble proteins having small molecular weights. LTPs participate in flower and seed development, cuticular wax deposition, also play important roles in pathogen and abiotic stress responses. A nonspecific LTP gene (SiLTP was isolated from a foxtail millet (Setaria italica suppression subtractive hybridization (SSH library enriched for differentially expressed genes after abiotic stress treatments. A semi-quantitative reverse transcriptase PCR analysis showed that SiLTP was expressed in all foxtail millet tissues. Additionally, the SiLTP promoter drove GUS expression in root tips, stems, leaves, flowers and siliques of transgenic Arabidopsis. Quantitative real-time PCR indicated that the SiLTP expression was induced by NaCl, polyethylene glycol and abscisic acid. SiLTP was localized in the cytoplasm of tobacco leaf epidermal cells and maize protoplasts. The ectopic expression of SiLTP in tobacco resulted in higher levels of salt and drought tolerance than in the wild type (WT. To further assess the function of SiLTP, SiLTP overexpression (OE and RNA interference (RNAi-based transgenic foxtail millet were obtained. SiLTP-OE lines performed better under salt and drought stresses compared with WT plants. In contrast, the RNAi lines were much more sensitive to salt and drought compared than WT. Electrophoretic mobility shift assays and yeast one-hybrids indicated that the transcription factor (TF ABA-responsive DRE-binding protein (SiARDP could bind to the dehydration-responsive element of SiLTP promoter in vitro and in vivo, respectively. Moreover, the SiLTP expression levels were higher in SiARDP-OE plants compared than the WT. These results confirmed that SiLTP plays important roles in improving salt and drought stress tolerance of foxtail millet, and may partly be up-regulated by SiARDP. SiLTP may provide an effective genetic resource for molecular breeding in crops to enhance salt and

Early life stress determines the effects of glucocorticoids and stress on hippocampal function: Electrophysiological and behavioral evidence respectively.

Science.gov (United States)

Pillai, Anup G; Arp, Marit; Velzing, Els; Lesuis, Sylvie L; Schmidt, Mathias V; Holsboer, Florian; Joëls, Marian; Krugers, Harm J

2018-05-01

Exposure to early-life adversity may program brain function to prepare individuals for adaptation to matching environmental contexts. In this study we tested this hypothesis in more detail by examining the effects of early-life stress - induced by raising offspring with limited nesting and bedding material from postnatal days 2-9 - in various behavioral tasks and on synaptic function in adult mice. Early-life stress impaired adult performance in the hippocampal dependent low-arousing object-in-context recognition memory task. This effect was absent when animals were exposed to a single stressor before training. Early-life stress did not alter high-arousing context and auditory fear conditioning. Early-life stress-induced behavioral modifications were not associated with alterations in the dendritic architecture of hippocampal CA1 pyramidal neurons or principal neurons of the basolateral amygdala. However, early-life stress reduced the ratio of NMDA to AMPA receptor-mediated excitatory postsynaptic currents and glutamate release probability specifically in hippocampal CA1 neurons, but not in the basolateral amygdala. These ex vivo effects in the hippocampus were abolished by acute glucocorticoid treatment. Our findings support that early-life stress can hamper object-in-context learning via pre- and postsynaptic mechanisms that affect hippocampal function but these effects are counteracted by acute stress or elevated glucocorticoid levels. Copyright © 2018. Published by Elsevier Ltd.

Quadrupole Transfer Function for Emittance Measurement

CERN Document Server

Cameron, Peter; Jansson, Andreas; Tan, Cheng-Yang

2008-01-01

Historically the use of the quadrupole moment measurement has been impeded by the requirement for large dynamic range, as well as measurement sensitivity to beam position. We investigate the use of the transfer function technique [1-3] in combination with the sensitivity and 160dB revolution line rejection of the direct diode detection analog front end [4] to open the possibility of an emittance diagnostic that may be implemented without operational complication, quasi- parasitic to the operation of existing tune measurement systems. Such a diagnostic would be particularly useful as an emittance monitor during acceleration ramp development in machines like RHIC and the LHC.

[Impact of Socioeconomic Risk Exposure on Maternal Sensitivity, Stress and Family Functionality].

Science.gov (United States)

Sidor, Anna; Köhler, Hubert; Cierpka, Manfred

2018-03-01

Impact of Socioeconomic Risk Exposure on Maternal Sensitivity, Stress and Family Functionality Parental stress exposure can influence the parent-child relationship, child development and child wellbeing in negative ways. The aim of this study was to investigate the impact of socio-economic risk exposure on the quality of the mother-child-interaction and family functionality. A sample of 294 mother-infant dyads at psychosocial risk was compared with a lower-risk, middle-class sample of 125 mother-infant-dyads in regard to maternal sensitivity/child's cooperation (CARE-Index), maternal stress (PSI-SF) and family functionality (FB-K). Lower levels of maternal sensitivity/child's cooperation and by trend also of the family functionality were found among the mothers from the at-risk sample in comparison to the low-risk sample. The level of maternal stress was similar in both samples. The results underpin the negative effects of a socio-economic risk exposure on the mother-child relationship. An early, sensitivity-focused family support could be encouraged to counteract the negative effects of early socioeconomic stress.

Determination of Hot-Carrier Distribution Functions in Uniaxially Stressed p-Type Germanium

DEFF Research Database (Denmark)

Christensen, Ove

1973-01-01

This paper gives a description of an experimental determination of distribution functions in k→ space of hot holes in uniaxially compressed germanium. The hot-carrier studies were made at 85°K at fields up to 1000 V/cm and uniaxial stresses up to 11 800 kg/cm2. The field and stress were always in...... probabilities with stress. A model based on the nonparabolicity of the upper p3 / 2 level is proposed for the negative differential conductivity in stressed p-type Ge....... function has been assumed. The parameters of the distribution function are then fitted to the experimental modulation. The calculation of absorption was performed numerically, using a four-band k→·p→ model. This model was checked for consistency by comparing with piezoabsorption measurements performed...... in thermal equilibrium. The average carrier energy calculated from the distribution function shows a fast increase with stress and almost saturates when the strain splitting of the two p3 / 2 levels reaches the optical-phonon energy. This saturation is interpreted in terms of the change in scattering...

Transfer function analysis of positron-emitting tracer imaging system (PETIS) data

International Nuclear Information System (INIS)

Keutgen, N.; Matsuhashi, S.; Mizuniwa, C.; Ito, T.; Fujimura, T.; Ishioka, N.S.; Watanabe, S.; Sekine, T.; Uchida, H.; Hashimoto, S.

2002-01-01

Quantitative analysis of the two-dimensional image data obtained with the positron-emitting tracer imaging system (PETIS) for plant physiology has been carried out using a transfer function analysis method. While a cut leaf base of Chinese chive (Allium tuberosum Rottler) or a cut stem of soybean (Glycine max L.) was immersed in an aqueous solution containing the [ 18 F] F - ion or [ 13 N]NO 3 - ion, tracer images of the leaf of Chinese chive and the trifoliate of soybean were recorded with PETIS. From the time sequence of images, the tracer transfer function was estimated from which the speed of tracer transport and the fraction moved between specified image positions were deduced

Stress and brain functional changes in patients with Crohn's disease: A functional magnetic resonance imaging study.

Science.gov (United States)

Agostini, A; Ballotta, D; Righi, S; Moretti, M; Bertani, A; Scarcelli, A; Sartini, A; Ercolani, M; Nichelli, P; Campieri, M; Benuzzi, F

2017-10-01

In Crohn's disease (CD) patients, stress is believed to influence symptoms generation. Stress may act via central nervous system pathways to affect visceral sensitivity and motility thus exacerbating gastrointestinal symptoms. The neural substrate underpinning these mechanisms needs to be investigated in CD. We conducted an explorative functional magnetic resonance imaging (fMRI) study in order to investigate potential differences in the brain stress response in CD patients compared to controls. 17 CD patients and 17 healthy controls underwent a fMRI scan while performing a stressful task consisting in a Stroop color-word interference task designed to induce mental stress in the fMRI environment. Compared to controls, in CD patients the stress task elicited greater blood oxygen level dependent (BOLD) signals in the midcingulate cortex (MCC). The MCC integrate "high" emotional processes with afferent sensory information ascending from the gut. In light of these integrative functions, the stress-evoked MCC hyperactivity in CD patients might represent a plausible neural substrate for the association between stress and symptomatic disease. The MCC dysfunction might be involved in mechanisms of central disinhibition of nociceptive inputs leading to amplify the visceral sensitivity. Finally, the stress-evoked MCC hyperactivity might affect the regulation of intestinal motility resulting in exacerbation of disease symptoms and the autonomic and neuroendocrine regulation of inflammation resulting in enhanced inflammatory activity. © 2017 John Wiley & Sons Ltd.

The partial coherence modulation transfer function in testing lithography lens

Science.gov (United States)

Huang, Jiun-Woei

2018-03-01

Due to the lithography demanding high performance in projection of semiconductor mask to wafer, the lens has to be almost free in spherical and coma aberration, thus, in situ optical testing for diagnosis of lens performance has to be established to verify the performance and to provide the suggesting for further improvement of the lens, before the lens has been build and integrated with light source. The measurement of modulation transfer function of critical dimension (CD) is main performance parameter to evaluate the line width of semiconductor platform fabricating ability for the smallest line width of producing tiny integrated circuits. Although the modulation transfer function (MTF) has been popularly used to evaluation the optical system, but in lithography, the contrast of each line-pair is in one dimension or two dimensions, analytically, while the lens stand along in the test bench integrated with the light source coherent or near coherent for the small dimension near the optical diffraction limit, the MTF is not only contributed by the lens, also by illumination of platform. In the study, the partial coherence modulation transfer function (PCMTF) for testing a lithography lens is suggested by measuring MTF in the high spatial frequency of in situ lithography lens, blended with the illumination of partial and in coherent light source. PCMTF can be one of measurement to evaluate the imperfect lens of lithography lens for further improvement in lens performance.

Child Behavior Problems, Teacher Executive Functions, and Teacher Stress in Head Start Classrooms.

Science.gov (United States)

Friedman-Krauss, Allison H; Raver, C Cybele; Neuspiel, Juliana M; Kinsel, John

2014-01-01

The current article explores the relationship between teachers' perceptions of child behavior problems and preschool teacher job stress, as well as the possibility that teachers' executive functions moderate this relationship. Data came from 69 preschool teachers in 31 early childhood classrooms in 4 Head Start centers and were collected using Web-based surveys and Web-based direct assessment tasks. Multilevel models revealed that higher levels of teachers' perceptions of child behavior problems were associated with higher levels of teacher job stress and that higher teacher executive function skills were related to lower job stress. However, findings did not yield evidence for teacher executive functions as a statistical moderator. Many early childhood teachers do not receive sufficient training for handling children's challenging behaviors. Child behavior problems increase a teacher's workload and consequently may contribute to feelings of stress. However, teachers' executive function abilities may enable them to use effective, cognitive-based behavior management and instructional strategies during interactions with students, which may reduce stress. Providing teachers with training on managing challenging behaviors and enhancing executive functions may reduce their stress and facilitate their use of effective classroom practices, which is important for children's school readiness skills and teachers' health.

Oxidative stress and lung function profiles of male smokers free from ...

African Journals Online (AJOL)

Oxidative stress and lung function profiles of male smokers free from COPD compared to those with COPD: A case-control study. ... However, conclusions about the role of blood or lung oxidative stress markers were disparate. Aims: To ... Keywords: inflammation; lung disease; spirometry; tobacco; sedentarily; stress oxidant ...

Testing and development of transfer functions for weighing precipitation gauges in WMO-SPICE

Directory of Open Access Journals (Sweden)

J. Kochendorfer

2018-02-01

Full Text Available Weighing precipitation gauges are used widely for the measurement of all forms of precipitation, and are typically more accurate than tipping-bucket precipitation gauges. This is especially true for the measurement of solid precipitation; however, weighing precipitation gauge measurements must still be adjusted for undercatch in snowy, windy conditions. In WMO-SPICE (World Meteorological Organization Solid Precipitation InterComparison Experiment, different types of weighing precipitation gauges and shields were compared, and adjustments were determined for the undercatch of solid precipitation caused by wind. For the various combinations of gauges and shields, adjustments using both new and previously existing transfer functions were evaluated. For most of the gauge and shield combinations, previously derived transfer functions were found to perform as well as those more recently derived. This indicates that wind shield type (or lack thereof is more important in determining the magnitude of wind-induced undercatch than the type of weighing precipitation gauge. It also demonstrates the potential for widespread use of the previously developed transfer functions. Another overarching result was that, in general, the more effective shields, which were associated with smaller unadjusted errors, also produced more accurate measurements after adjustment. This indicates that although transfer functions can effectively reduce measurement biases, effective wind shielding is still required for the most accurate measurement of solid precipitation.

Testing and development of transfer functions for weighing precipitation gauges in WMO-SPICE

Science.gov (United States)

Kochendorfer, John; Nitu, Rodica; Wolff, Mareile; Mekis, Eva; Rasmussen, Roy; Baker, Bruce; Earle, Michael E.; Reverdin, Audrey; Wong, Kai; Smith, Craig D.; Yang, Daqing; Roulet, Yves-Alain; Meyers, Tilden; Buisan, Samuel; Isaksen, Ketil; Brækkan, Ragnar; Landolt, Scott; Jachcik, Al

2018-02-01

Weighing precipitation gauges are used widely for the measurement of all forms of precipitation, and are typically more accurate than tipping-bucket precipitation gauges. This is especially true for the measurement of solid precipitation; however, weighing precipitation gauge measurements must still be adjusted for undercatch in snowy, windy conditions. In WMO-SPICE (World Meteorological Organization Solid Precipitation InterComparison Experiment), different types of weighing precipitation gauges and shields were compared, and adjustments were determined for the undercatch of solid precipitation caused by wind. For the various combinations of gauges and shields, adjustments using both new and previously existing transfer functions were evaluated. For most of the gauge and shield combinations, previously derived transfer functions were found to perform as well as those more recently derived. This indicates that wind shield type (or lack thereof) is more important in determining the magnitude of wind-induced undercatch than the type of weighing precipitation gauge. It also demonstrates the potential for widespread use of the previously developed transfer functions. Another overarching result was that, in general, the more effective shields, which were associated with smaller unadjusted errors, also produced more accurate measurements after adjustment. This indicates that although transfer functions can effectively reduce measurement biases, effective wind shielding is still required for the most accurate measurement of solid precipitation.

Stress transfer around a broken fiber in unidirectional fiber-reinforced composites considering matrix damage evolution and interface slipping

Science.gov (United States)

Yang, Zhong; Zhang, BoMing; Zhao, Lin; Sun, XinYang

2011-02-01

A shear-lag model is applied to study the stress transfer around a broken fiber within unidirectional fiber-reinforced composites (FRC) subjected to uniaxial tensile loading along the fiber direction. The matrix damage and interfacial debonding, which are the main failure modes, are considered in the model. The maximum stress criterion with the linear damage evolution theory is used for the matrix. The slipping friction stress is considered in the interfacial debonding region using Coulomb friction theory, in which interfacial clamping stress comes from radial residual stress and mismatch of Poisson's ratios of constituents (fiber and matrix). The stress distributions in the fiber and matrix are obtained by the shear-lag theory added with boundary conditions, which includes force continuity and displacement compatibility constraints in the broken and neighboring intact fibers. The result gives axial stress distribution in fibers and shear stress in the interface and compares the theory reasonably well with the measurement by a polarized light microscope. The relation curves between damage, debonding and ineffective region lengths with external strain loading are obtained.

A Novel Shape-Free Plane Quadratic Polygonal Hybrid Stress-Function Element

Directory of Open Access Journals (Sweden)

Pei-Lei Zhou

2015-01-01

Full Text Available A novel plane quadratic shape-free hybrid stress-function (HS-F polygonal element is developed by employing the principle of minimum complementary energy and the fundamental analytical solutions of the Airy stress function. Without construction of displacement interpolation function, the formulations of the new model are much simpler than those of the displacement-based polygonal elements and can be degenerated into triangular or quadrilateral elements directly. In particular, it is quite insensitive to various mesh distortions and even can keep precision when element shape is concave. Furthermore, the element does not show any spurious zero energy modes. Numerical examples show the excellent performance of the new element, denoted by HSF-AP-19β, in both displacement and stress solutions.

Stress intensity factors and weight functions for cracks in front of notches

International Nuclear Information System (INIS)

Fett, T.

1993-12-01

The knowledge of stress intensity factors for cracks at notch roots is important for the fracture mechanical treatment of real components. Stress intensity factor solutions are available only for special notches and externally applied loads. For the treatment of more complex loadings as thermal stresses near the notch root the weight function is needed in addition. In the first part of this report weight functions for cracks in front of internal notches are derived from stress intensity factor solutions under external loading available in the literature. The second part deals with cracks in front of edge notches. Limit cases of stress intensity factors are derived which allow to estimate stress intensity factors for cracks in front of internal elliptical notches with arbitrary aspect ratio of the ellipse and for external notches. (orig.) [de

Stress proteins and the immune response.

Science.gov (United States)

Moseley, P

2000-07-25

The heat shock or stress response is one of the most highly conserved adaptive responses in nature. In single cell organisms, the stress response confers tolerance to a variety of stresses including hyperthermia, hyperoxia, hypoxia, and other perturbations, which alter protein synthesis. This tolerance phenomenon is also extremely important in the multicellular organism, resulting in not only thermal tolerance, but also resistance to stresses of the whole organism such as ischemia-reperfusion injury. Moreover, recent data indicates that these stress proteins have the ability to modulate the cellular immune response. Although the terms heat shock proteins (HSPs) and stress proteins are often used interchangeably, the term stress proteins includes the HSPs, the glucose-regulated proteins (GRPs) and ubiquitin. The stress proteins may be grouped by molecular weight ranging from the large 110 kDa HSP110 to ubiquitin at 8 kDa. These proteins serve as cellular chaperones, participating in protein synthesis and transport through the various cellular compartments. Because these proteins have unique cellular localizations, the chaperone function of the stress proteins often involves a transfer of peptides between stress proteins as the peptide is moved between cellular compartments. For example, HSP70 is a cytosolic and nuclear chaperone, which is critical for the transfer of cellular peptides in the mitochondrion through a hand-off that involves mitochondrial HSP60 at the inner mitochondrial membrane. Similarly, cytosolic proteins are transferred from HSP70 to gp96 as they move into the endoplasmic reticulum. The central role of the stress proteins in the transfer of peptides through the cell may be responsible for the recently recognized importance of the stress proteins in the modulation of the immune system [Feder, M.E., Hofmann, G.E., 1999. Heat-shock proteins, molecular chaperones, and the stress response: evolutionary and ecological physiology. Annu. Rev. Physiol. 61

Effects of heat stress on baroreflex function in humans

Science.gov (United States)

Crandall, Craig G.; Cui, Jian; Wilson, Thad E.

2003-01-01

INTRODUCTION: Heat stress significantly reduces orthostatic tolerance in humans. The mechanism(s) causing this response remain unknown. The purpose of this review article is to present data pertaining to the hypothesis that reduced orthostatic tolerance in heat stressed individuals is a result of heat stress induced alterations in baroflex function. METHODS: In both normothermic and heat stressed conditions baroreflex responsiveness was assessed via pharmacological and non-pharmacological methods. In addition, the effects of heat stress on post-synaptic vasoconstrictor responsiveness were assessed. RESULTS: Generally, whole body heating did not alter baroreflex sensitivity defined as the gain of the linear portion of the baroreflex curve around the operating point. However, whole body heating shifted the baroreflex curve to the prevailing (i.e. elevated) heart rate and muscle sympathetic nerve activity. Finally, the heat stress impaired vasoconstrictor responses to exogenous administration of adrenergic agonists. CONCLUSION: Current data do not support the hypothesis that reduced orthostatic tolerance associated with heat stress in humans is due to impaired baroreflex responsiveness. This phenomenon may be partially due to the effects of heat stress on reducing vasoconstrictor responsiveness.

Transfer-messenger RNA controls the translation of cell-cycle and stress proteins in Streptomyces

DEFF Research Database (Denmark)

Barends, Sharief; Zehl, Martin; Bialek, Sylwia

2010-01-01

coelicolor, trans-translation has a specialized role in stress management. Analysis of proteins that were carboxy-terminally His(8)-tagged by a recombinant tmRNA identified only 10 targets, including the stress proteins: DnaK heat-shock protein 70, thiostrepton-induced protein A, universal stress protein A...... functionality for tmRNA, promoting the translation of the same mRNA it targets, at the expense of sacrificing the first nascent protein. In streptomycetes, tmRNA has evolved into a dedicated task force that ensures the instantaneous response to the exposure to stress....

The evolution of the mass-transfer functions in liquid Yukawa systems

Energy Technology Data Exchange (ETDEWEB)

Vaulina, O. S., E-mail: olga.vaulina@bk.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2016-09-15

The results of analytic and numerical investigation of mass-transfer processes in nonideal liquid systems are reported. Calculations are performed for extended 2D and 3D systems of particles that interact with a screened Yukawa-type Coulomb potential. The main attention is paid to 2D structures. A new analytic model is proposed for describing the evolution of mass-transfer functions in systems of interacting particles, including the transition between the ballistic and diffusion regimes of their motion.

Child Behavior Problems, Teacher Executive Functions, and Teacher Stress in Head Start Classrooms

Science.gov (United States)

Friedman-Krauss, Allison H.; Raver, C. Cybele; Neuspiel, Juliana M.; Kinsel, John

2017-01-01

Research Findings The current article explores the relationship between teachers’ perceptions of child behavior problems and preschool teacher job stress, as well as the possibility that teachers’ executive functions moderate this relationship. Data came from 69 preschool teachers in 31 early childhood classrooms in 4 Head Start centers and were collected using Web-based surveys and Web-based direct assessment tasks. Multilevel models revealed that higher levels of teachers’ perceptions of child behavior problems were associated with higher levels of teacher job stress and that higher teacher executive function skills were related to lower job stress. However, findings did not yield evidence for teacher executive functions as a statistical moderator. Practice or Policy Many early childhood teachers do not receive sufficient training for handling children’s challenging behaviors. Child behavior problems increase a teacher’s workload and consequently may contribute to feelings of stress. However, teachers’ executive function abilities may enable them to use effective, cognitive-based behavior management and instructional strategies during interactions with students, which may reduce stress. Providing teachers with training on managing challenging behaviors and enhancing executive functions may reduce their stress and facilitate their use of effective classroom practices, which is important for children’s school readiness skills and teachers’ health. PMID:28596698

Linear and non-linear dose-response functions reveal a hormetic relationship between stress and learning.

Science.gov (United States)

Zoladz, Phillip R; Diamond, David M

2008-10-16

Over a century of behavioral research has shown that stress can enhance or impair learning and memory. In the present review, we have explored the complex effects of stress on cognition and propose that they are characterized by linear and non-linear dose-response functions, which together reveal a hormetic relationship between stress and learning. We suggest that stress initially enhances hippocampal function, resulting from amygdala-induced excitation of hippocampal synaptic plasticity, as well as the excitatory effects of several neuromodulators, including corticosteroids, norepinephrine, corticotropin-releasing hormone, acetylcholine and dopamine. We propose that this rapid activation of the amygdala-hippocampus brain memory system results in a linear dose-response relation between emotional strength and memory formation. More prolonged stress, however, leads to an inhibition of hippocampal function, which can be attributed to compensatory cellular responses that protect hippocampal neurons from excitotoxicity. This inhibition of hippocampal functioning in response to prolonged stress is potentially relevant to the well-described curvilinear dose-response relationship between arousal and memory. Our emphasis on the temporal features of stress-brain interactions addresses how stress can activate, as well as impair, hippocampal functioning to produce a hormetic relationship between stress and learning.

Family functioning, parenting stress and quality of life in mothers and fathers of Polish children with high functioning autism or Asperger syndrome.

Science.gov (United States)

Pisula, Ewa; Porębowicz-Dörsmann, Anna

2017-01-01

The aim of the study was to investigate the perception of the family functioning in parents of children with autism spectrum disorders (ASD) with normal-range intelligence and the relationships between family functioning, parenting stress and quality of life. Dyads of parents of children with ASD without intellectual disability and parents of typically developing children (controls) completed a set of self-report questionnaires. Parents of children with ASD reported lower functioning of the family as a whole and their own functioning as family members; they exhibited higher levels of parenting stress and lower quality of life. Mothers of children with ASD experienced more stress in personal domain than fathers. Relationships between family functioning, parenting stress and quality of life have been established. There were also moderate to strong correlations in mother-father dyads between their assessments of family functioning, parenting stress and QoL in social relationships and environmental domains.

Transfer function modeling of parallel connected two three-phase induction motor implementation using LabView platform

DEFF Research Database (Denmark)

Gunabalan, R.; Sanjeevikumar, P.; Blaabjerg, Frede

2015-01-01

This paper presents the transfer function modeling and stability analysis of two induction motors of same ratings and parameters connected in parallel. The induction motors are controlled by a single inverter and the entire drive system is modeled using transfer function in LabView. Further...

Dynamic regulation of NMDAR function in the adult brain by the stress hormone corticosterone

Directory of Open Access Journals (Sweden)

Yiu Chung eTse

2012-03-01

Full Text Available Stress and corticosteroids dynamically modulate the expression of synaptic plasticity at glutamatergic synapses in the developed brain. Together with alpha-amino-3-hydroxy-methyl-4-isoxazole propionic acid receptors (AMPAR, N-methyl-D-aspartate receptors (NMDAR are critical mediators of synaptic function and are essential for the induction of many forms of synaptic plasticity. Regulation of NMDAR function by cortisol/corticosterone (CORT may be fundamental to the effects of stress on synaptic plasticity. Recent reports of the efficacy of NMDAR antagonists in treating certain stress-associated psychopathologies further highlight the importance of understanding the regulation of NMDAR function by CORT. Knowledge of how corticosteroids regulate NMDAR function within the adult brain is relatively sparse, perhaps due to a common belief that NMDAR function is relatively stable in the adult brain. We review recent results from our laboratory and others demonstrating dynamic regulation of NMDAR function by CORT in the adult brain. In addition, we consider the issue of how differences in the early life environment may program differential sensitivity to modulation of NMDAR function by CORT and how this may influence synaptic function during stress. Findings from these studies demonstrate that NMDAR function in the adult hippocampus remains sensitive to even brief exposures to CORT and that the capacity for modulation of NMDAR may be programmed, in part, by the early life environment. Modulation of NMDAR function may contribute to dynamic regulation of synaptic plasticity and adaptation in the face of stress, however enhanced NMDAR function may be implicated in mechanisms of stress related psychopathologies including depression.

Power and power-to-flow reactivity transfer functions in EBR-II [Experimental Breeder Reactor II] fuel

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1989-01-01

Reactivity transfer functions are important in determining the reactivity history during a power transient. Overall nodal transfer functions have been calculated for different subassembly types in the Experimental Breeder Reactor II (EBR-II). Steady-state calculations for temperature changes and, hence, reactivities for power changes have been separated into power and power-to-flow-dependent terms. Axial nodal transfer functions separated into power and power-to-flow-dependent components are reported in this paper for a typical EBR-II fuel pin. This provides an improved understanding of the time dependence of these components in transient situations

Parenting stress in pediatric IBD: relations with child psychopathology, family functioning, and disease severity.

Science.gov (United States)

Gray, Wendy N; Graef, Danielle M; Schuman, Shana S; Janicke, David M; Hommel, Kevin A

2013-05-01

Parenting stress in pediatric inflammatory bowel disease (IBD) has been under-examined. Data validating use of the Pediatric Inventory for Parents (PIP), a measure of parenting stress associated with caring for a chronically ill child, in chronic diseases with intermittent, unpredictable disease courses, such as IBD, are needed. This study presents validity data in support of the PIP in pediatric IBD and examines relations between parenting stress and important psychosocial and medical outcomes. Adolescents (N = 130) with IBD and their caregivers across 3 sites completed measures of parenting stress, family functioning, and emotional/behavioral functioning. Disease severity was also assessed for each participant. The PIP demonstrates excellent internal consistency. Parenting stress was significantly higher among those with unhealthy general family functioning and those with children with borderline or clinically elevated internalizing symptoms. Caregiving stress was greater among parents of youth with more active Crohn's disease. Results supported the reliability and validity of the PIP for assessing caregiving stress in pediatric IBD. Routine assessment of parenting stress is recommended, particularly among parents reporting unhealthy family functioning and parents of youth with borderline or clinically elevated internalizing symptoms and more active disease.

Executive Functions in Students With Depression, Anxiety, and Stress Symptoms.

Science.gov (United States)

Ajilchi, Bita; Nejati, Vahid

2017-01-01

This study aimed to investigate and compare the executive functions of students with depression, anxiety, and stress symptoms with those functions in healthy ones. This study was a comparative and non-clinical analysis. The study population comprised all students of Shahid Beheshti University, Tehran, Iran. A total of 448 students were recruited using convenience sampling method. They were also screened using the Depression Anxiety Stress Scales (DASS) test comprising 21 items. Of study participants, 30 people were depressed, 27 had anxiety, and 15 suffered from stress. Then, 50 control people were matched with them. Next, both groups were compared using the Stroop test, Wisconsin card sorting, and cognitive ability test. Using MANOVA test, data analysis revealed no significant differences among 4 groups with regard to selective attention and shifting attention. Depressed group reacted rapidly as opposed to the anxiety group with regard to measures of shifting attention and cognitive abilities; it was observed that the memory, inhibition control, planning, and flexibility of the healthy group were better than those of the 3 other groups. The findings of this research raised specific issues in relation to the role of depression, anxiety, and stress in the disruption of the executive functions of sufferers. Selective and shifting attention and cognitive abilities are specifically affected in this regard. Meanwhile, the role of stress in impairing decision making and the major role of anxiety in impairing sustained attention was shown to be considerable.

Excitation functions for quasielastic transfer reactions induced with heavy ions in bismuth

International Nuclear Information System (INIS)

Gardes, D.; Bimbot, R.; Maison, J.; de Reilhac, L.; Rivet, M.F.; Fleury, A.; Hubert, F.; Llabador, Y.

1978-01-01

The excitation functions for the production of 210 Bi, 210 Po, /sup 207-211/At, and 211 Rn through quasielastic transfer reactions induced with heavy ions in 209 Bi have been measured. The corresponding reactions involved the transfer of one neutron, one proton, two charges, and three charges from projectile to target. The projectiles used were 12 C, 14 N, 16 O, 19 F, 20 Ne, 40 Ar, 40 Ca, 56 Fe, and 63 Cu. The experimental techniques involved target irradiations and off-line α and γ activity measurements. Chemical separations were used to solve specific problems. Careful measuremnts of incident energies and cross sections were performed close to the reaction thresholds. All excitation functions exhibit the typical features of quasielastic transfer reactions: a sharp increase at low energy, and a constant value at high incident energy. The position of the thresholds are strongly influenced by the energetics of the reaction: High cross sections are observed under the strong interaction barrier if the energy balance at the minimum distance of approach is positive. This balance is equal to the difference between the interaction potentials in the entrance and exit channels, corrected for the mass balance. The constant cross sections observed for the high energy part of a given excitation function are consistent with the assumption that the curve P (R) which represents the transfer probability versus the distance between the nucleus centers does not vary with incident energy. This assumption implies the constancy of the optimum distance of approach R/sub opt/, of the R window ΔR for which P (R) is significant, and of the magnitude of P (R). Moreover the data show that the high energy cross sections for one-proton transfer are independent of the projectile, while odd-even effects of the projectile atomic number Z on the two-charge transfer cross sections are observed for the lightest incident ions 14 N to 20 Ne

A binaural advantage in the subjective modulation transfer function with simple impulse responses

DEFF Research Database (Denmark)

Thompson, Eric Robert; Dau, Torsten

2008-01-01

into account that humans listen with two ears. There can be large interaural phase differences in the modulation transfer functions, which can create detectable interaural level difference fluctuations. Measurements were made to determine whether these interaural modulation phase differences can be used......The speech transmission index (STI) has been a popular method for predicting speech intelligibility in rooms. It is based on the magnitude of the modulation transfer function, which can be derived from the impulse response of the room and the background noise levels. However, it does not take...

Characterizing short-term stability for Boolean networks over any distribution of transfer functions

International Nuclear Information System (INIS)

Seshadhri, C.; Smith, Andrew M.; Vorobeychik, Yevgeniy; Mayo, Jackson R.; Armstrong, Robert C.

2016-01-01

Here we present a characterization of short-term stability of random Boolean networks under arbitrary distributions of transfer functions. Given any distribution of transfer functions for a random Boolean network, we present a formula that decides whether short-term chaos (damage spreading) will happen. We provide a formal proof for this formula, and empirically show that its predictions are accurate. Previous work only works for special cases of balanced families. Finally, it has been observed that these characterizations fail for unbalanced families, yet such families are widespread in real biological networks.

Vector Green's function algorithm for radiative transfer in plane-parallel atmosphere

Energy Technology Data Exchange (ETDEWEB)

Qin Yi [School of Physics, University of New South Wales (Australia)]. E-mail: yi.qin@csiro.au; Box, Michael A. [School of Physics, University of New South Wales (Australia)

2006-01-15

Green's function is a widely used approach for boundary value problems. In problems related to radiative transfer, Green's function has been found to be useful in land, ocean and atmosphere remote sensing. It is also a key element in higher order perturbation theory. This paper presents an explicit expression of the Green's function, in terms of the source and radiation field variables, for a plane-parallel atmosphere with either vacuum boundaries or a reflecting (BRDF) surface. Full polarization state is considered but the algorithm has been developed in such way that it can be easily reduced to solve scalar radiative transfer problems, which makes it possible to implement a single set of code for computing both the scalar and the vector Green's function.

Maternal Parenting Stress and Child Perception of Family Functioning Among Families Affected by HIV.

Science.gov (United States)

Schulte, Marya T; Armistead, Lisa; Marelich, William D; Payne, Diana L; Goodrum, Nada M; Murphy, Debra A

Mothers living with HIV (MLWH) experience stressors inherent to parenting, often within a context characterized by poverty, stigma, and/or limited social support. Our study assessed the relationship between parenting stress and child perceptions of family functioning in families with MLWH who have healthy school-age children. MLWH and their children (N = 102 pairs) completed measures addressing parenting stress and perceptions of family functioning (i.e., parent-child communication, family routines, and family cohesion). We used covariance structural modeling to evaluate the relationship between these factors, with results showing greater maternal parenting stress associated with poorer family functioning outcomes (reported by both the child and the mother). Findings offer support for the parenting stress-family functioning relationship by providing the child perspective along with the maternal perspective, and point to the need for interventions aimed at minimizing the impact of maternal parenting stress on family functioning. Copyright © 2017 Association of Nurses in AIDS Care. Published by Elsevier Inc. All rights reserved.

Stress assessment based on EEG univariate features and functional connectivity measures.

Science.gov (United States)

Alonso, J F; Romero, S; Ballester, M R; Antonijoan, R M; Mañanas, M A

2015-07-01

The biological response to stress originates in the brain but involves different biochemical and physiological effects. Many common clinical methods to assess stress are based on the presence of specific hormones and on features extracted from different signals, including electrocardiogram, blood pressure, skin temperature, or galvanic skin response. The aim of this paper was to assess stress using EEG-based variables obtained from univariate analysis and functional connectivity evaluation. Two different stressors, the Stroop test and sleep deprivation, were applied to 30 volunteers to find common EEG patterns related to stress effects. Results showed a decrease of the high alpha power (11 to 12 Hz), an increase in the high beta band (23 to 36 Hz, considered a busy brain indicator), and a decrease in the approximate entropy. Moreover, connectivity showed that the high beta coherence and the interhemispheric nonlinear couplings, measured by the cross mutual information function, increased significantly for both stressors, suggesting that useful stress indexes may be obtained from EEG-based features.

Changes in ventricular function during emotional stress and cold exposure

International Nuclear Information System (INIS)

Kiess, M.C.; Moore, R.A.; Dimsdale, J.; Alpert, N.M.; Boucher, C.A.; Strauss, H.W.

1984-01-01

Patients with cardiac disease frequently develop symptoms with emotional stress or cold exposure. To investigate the effects of these stresses in normal subjects, an ambulatory ventricular function monitor (VEST) (previously reported to measure EFs which correlate well with gamma camera measurements) was employed to record sequential 2 minute time activity curves from the left ventricles of 6 healthy men (ages 19-24) during a control period and during a 30 minute stress interview with a psychiatrist. Four of the subjects were also monitored in a cold room (1 0 C) for 20 min. In addition to the left ventricular time-activity curve, heart rate (HR), and BP (cuff) were recorded. All subjects had increases in HR, BP and EF during the stress interview. Cold, however, produced decreases in HR and EF and an increase in BP. The results (mean +- SD) are tabulated. End-systolic and end-diastolic counts and hence volume decreased during the interview and increased during cold exposure. The results suggest that (1) ambulatory changes in ventricular function can be measured with the VEST, and (2) significant changes in cardiovascular physiology are seen in normal subjects during a stress interview and exposure to cold

Family functioning, parenting stress and quality of life in mothers and fathers of Polish children with high functioning autism or Asperger syndrome.

Directory of Open Access Journals (Sweden)

Ewa Pisula

Full Text Available The aim of the study was to investigate the perception of the family functioning in parents of children with autism spectrum disorders (ASD with normal-range intelligence and the relationships between family functioning, parenting stress and quality of life. Dyads of parents of children with ASD without intellectual disability and parents of typically developing children (controls completed a set of self-report questionnaires. Parents of children with ASD reported lower functioning of the family as a whole and their own functioning as family members; they exhibited higher levels of parenting stress and lower quality of life. Mothers of children with ASD experienced more stress in personal domain than fathers. Relationships between family functioning, parenting stress and quality of life have been established. There were also moderate to strong correlations in mother-father dyads between their assessments of family functioning, parenting stress and QoL in social relationships and environmental domains.

Directional resolution of head-related transfer functions required in binaural synthesis

DEFF Research Database (Denmark)

Minnaar, Pauli; Plogsties, Jan; Christensen, Flemming

2005-01-01

In binaural synthesis a virtual sound source is implemented by convolving an anechoic signal with a pair of head-related transfer functions (HRTFs). In order to represent all possible directions of the sound source with respect to the listener a discrete number of HRTFs are measured and interpola......In binaural synthesis a virtual sound source is implemented by convolving an anechoic signal with a pair of head-related transfer functions (HRTFs). In order to represent all possible directions of the sound source with respect to the listener a discrete number of HRTFs are measured...... and moving sound sources. A criterion was found that predicts the experimental results. This criterion was used to estimate the directional resolution required in binaural synthesis for all directions on the sphere around the head....

A Non-specific Setaria italica Lipid Transfer Protein Gene Plays a Critical Role under Abiotic Stress.

Science.gov (United States)

Pan, Yanlin; Li, Jianrui; Jiao, Licong; Li, Cong; Zhu, Dengyun; Yu, Jingjuan

2016-01-01

Lipid transfer proteins (LTPs) are a class of cysteine-rich soluble proteins having small molecular weights. LTPs participate in flower and seed development, cuticular wax deposition, also play important roles in pathogen and abiotic stress responses. A non-specific LTP gene ( SiLTP ) was isolated from a foxtail millet ( Setaria italica ) suppression subtractive hybridization library enriched for differentially expressed genes after abiotic stress treatments. A semi-quantitative reverse transcriptase PCR analysis showed that SiLTP was expressed in all foxtail millet tissues. Additionally, the SiLTP promoter drove GUS expression in root tips, stems, leaves, flowers, and siliques of transgenic Arabidopsis . Quantitative real-time PCR indicated that the SiLTP expression was induced by NaCl, polyethylene glycol, and abscisic acid (ABA). SiLTP was localized in the cytoplasm of tobacco leaf epidermal cells and maize protoplasts. The ectopic expression of SiLTP in tobacco resulted in higher levels of salt and drought tolerance than in the wild type (WT). To further assess the function of SiLTP, SiLTP overexpression (OE) and RNA interference (RNAi)-based transgenic foxtail millet were obtained. SiLTP -OE lines performed better under salt and drought stresses compared with WT plants. In contrast, the RNAi lines were much more sensitive to salt and drought compared than WT. Electrophoretic mobility shift assays and yeast one-hybrids indicated that the transcription factor ABA-responsive DRE-binding protein (SiARDP) could bind to the dehydration-responsive element of SiLTP promoter in vitro and in vivo , respectively. Moreover, the SiLTP expression levels were higher in SiARDP -OE plants compared than the WT. These results confirmed that SiLTP plays important roles in improving salt and drought stress tolerance of foxtail millet, and may partly be upregulated by SiARDP. SiLTP may provide an effective genetic resource for molecular breeding in crops to enhance salt and drought

Teacher Stress Predicts Child Executive Function: Moderation by School Poverty

Science.gov (United States)

Neuenschwander, Regula; Friedman-Krauss, Allison; Raver, Cybele; Blair, Clancy

2017-01-01

Research Findings: Recent research has explored relations between classroom quality and child executive function (EF), but little is known about how teachers' well-being, including stress, relates to child EF--a crucial component of self-regulation. We hypothesized that teacher stress is negatively or curvilinearly related to child EF and…

Endoplasmic reticulum: ER stress regulates mitochondrial bioenergetics

Science.gov (United States)

Bravo, Roberto; Gutierrez, Tomás; Paredes, Felipe; Gatica, Damián; Rodriguez, Andrea E.; Pedrozo, Zully; Chiong, Mario; Parra, Valentina; Quest, Andrew F.G.; Rothermel, Beverly A.; Lavandero, Sergio

2014-01-01

Endoplasmic reticulum (ER) stress activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. The molecular mechanisms responsible for execution of the cell death program are relatively well characterized, but the metabolic events taking place during the adaptive phase of ER stress remain largely undefined. Here we discuss emerging evidence regarding the metabolic changes that occur during the onset of ER stress and how ER influences mitochondrial function through mechanisms involving calcium transfer, thereby facilitating cellular adaptation. Finally, we highlight how dysregulation of ER–mitochondrial calcium homeostasis during prolonged ER stress is emerging as a novel mechanism implicated in the onset of metabolic disorders. PMID:22064245

Wheat EST resources for functional genomics of abiotic stress

Directory of Open Access Journals (Sweden)

Links Matthew G

2006-06-01

Full Text Available Abstract Background Wheat is an excellent species to study freezing tolerance and other abiotic stresses. However, the sequence of the wheat genome has not been completely characterized due to its complexity and large size. To circumvent this obstacle and identify genes involved in cold acclimation and associated stresses, a large scale EST sequencing approach was undertaken by the Functional Genomics of Abiotic Stress (FGAS project. Results We generated 73,521 quality-filtered ESTs from eleven cDNA libraries constructed from wheat plants exposed to various abiotic stresses and at different developmental stages. In addition, 196,041 ESTs for which tracefiles were available from the National Science Foundation wheat EST sequencing program and DuPont were also quality-filtered and used in the analysis. Clustering of the combined ESTs with d2_cluster and TGICL yielded a few large clusters containing several thousand ESTs that were refractory to routine clustering techniques. To resolve this problem, the sequence proximity and "bridges" were identified by an e-value distance graph to manually break clusters into smaller groups. Assembly of the resolved ESTs generated a 75,488 unique sequence set (31,580 contigs and 43,908 singletons/singlets. Digital expression analyses indicated that the FGAS dataset is enriched in stress-regulated genes compared to the other public datasets. Over 43% of the unique sequence set was annotated and classified into functional categories according to Gene Ontology. Conclusion We have annotated 29,556 different sequences, an almost 5-fold increase in annotated sequences compared to the available wheat public databases. Digital expression analysis combined with gene annotation helped in the identification of several pathways associated with abiotic stress. The genomic resources and knowledge developed by this project will contribute to a better understanding of the different mechanisms that govern stress tolerance in

Hypothesis: NDL proteins function in stress responses by regulating microtubule organization.

Science.gov (United States)

Khatri, Nisha; Mudgil, Yashwanti

2015-01-01

N-MYC DOWNREGULATED-LIKE proteins (NDL), members of the alpha/beta hydrolase superfamily were recently rediscovered as interactors of G-protein signaling in Arabidopsis thaliana. Although the precise molecular function of NDL proteins is still elusive, in animals these proteins play protective role in hypoxia and expression is induced by hypoxia and nickel, indicating role in stress. Homology of NDL1 with animal counterpart N-MYC DOWNREGULATED GENE (NDRG) suggests similar functions in animals and plants. It is well established that stress responses leads to the microtubule depolymerization and reorganization which is crucial for stress tolerance. NDRG is a microtubule-associated protein which mediates the microtubule organization in animals by causing acetylation and increases the stability of α-tubulin. As NDL1 is highly homologous to NDRG, involvement of NDL1 in the microtubule organization during plant stress can also be expected. Discovery of interaction of NDL with protein kinesin light chain- related 1, enodomembrane family protein 70, syntaxin-23, tubulin alpha-2 chain, as a part of G protein interactome initiative encourages us to postulate microtubule stabilizing functions for NDL family in plants. Our search for NDL interactors in G protein interactome also predicts the role of NDL proteins in abiotic stress tolerance management. Based on published report in animals and predicted interacting partners for NDL in G protein interactome lead us to hypothesize involvement of NDL in the microtubule organization during abiotic stress management in plants.

Perpetual pavement – absorbing stress and functional maintenance

Directory of Open Access Journals (Sweden)

Rong Gao

2017-03-01

Full Text Available Perpetual Pavement combines the well documented smoothness and safety advantages of asphalt with an advanced, multi-layer paving design process, that with routine maintenance, extends the useful life of a roadway. Perpetual provides long lasting road and smoothness for the construction purposes. This study has the design key points of perpetual pavement based on the idea of life cycle, which has a new direction for the new highway construction, reconstruction and expansion. First, the structure of long life pavement design is studied to analyze the effect of stress absorbing layer. Second, researches on stress absorbing layer from the aspects of raw materials, mix proportion are implemented. Third, the design index of stress absorbing layer is determined by the shear strength test. The results show that the design idea of composite perpetual pavement can be realized by reasonable design of the stress absorbing layer and carrying out the surface functional maintenance can ensure the pavement to avoid structural damage in the operation stage.

Transfer functions for protein signal transduction: application to a model of striatal neural plasticity.

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Gabriele Scheler

Full Text Available We present a novel formulation for biochemical reaction networks in the context of protein signal transduction. The model consists of input-output transfer functions, which are derived from differential equations, using stable equilibria. We select a set of "source" species, which are interpreted as input signals. Signals are transmitted to all other species in the system (the "target" species with a specific delay and with a specific transmission strength. The delay is computed as the maximal reaction time until a stable equilibrium for the target species is reached, in the context of all other reactions in the system. The transmission strength is the concentration change of the target species. The computed input-output transfer functions can be stored in a matrix, fitted with parameters, and even recalled to build dynamical models on the basis of state changes. By separating the temporal and the magnitudinal domain we can greatly simplify the computational model, circumventing typical problems of complex dynamical systems. The transfer function transformation of biochemical reaction systems can be applied to mass-action kinetic models of signal transduction. The paper shows that this approach yields significant novel insights while remaining a fully testable and executable dynamical model for signal transduction. In particular we can deconstruct the complex system into local transfer functions between individual species. As an example, we examine modularity and signal integration using a published model of striatal neural plasticity. The modularizations that emerge correspond to a known biological distinction between calcium-dependent and cAMP-dependent pathways. Remarkably, we found that overall interconnectedness depends on the magnitude of inputs, with higher connectivity at low input concentrations and significant modularization at moderate to high input concentrations. This general result, which directly follows from the properties of

Functionalized polymer film surfaces via surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Hu, Y.; Li, J.S.; Yang, W.T.; Xu, F.J.

2013-01-01

The ability to manipulate and control the surface properties of polymer films, without altering the substrate properties, is crucial to their wide-spread applications. In this work, a simple one-step method for the direct immobilization of benzyl chloride groups (as the effective atom transfer radical polymerization (ATRP) initiators) on the polymer films was developed via benzophenone-induced coupling of 4-vinylbenzyl chloride (VBC). Polyethylene (PE) and nylon films were selected as examples of polymer films to illustrate the functionalization of film surfaces via surface-initiated ATRP. Functional polymer brushes of (2-dimethylamino)ethyl methacrylate, sodium 4-styrenesulfonate, 2-hydroxyethyl methacrylate and glycidyl methacrylate, as well as their block copolymer brushes, have been prepared via surface-initiated ATRP from the VBC-coupled PE or nylon film surfaces. With the development of a simple approach to the covalent immobilization of ATRP initiators on polymer film surfaces and the inherent versatility of surface-initiated ATRP, the surface functionality of polymer films can be precisely tailored. - Highlights: ► Atom transfer radical polymerization initiators were simply immobilized. ► Different functional polymer brushes were readily prepared. ► Their block copolymer brushes were also readily prepared

Thermal Stress Analysis of a Continuous and Pulsed End-Pumped Nd:YAG Rod Crystal Using Non-Classic Conduction Heat Transfer Theory

Science.gov (United States)

Mojahedi, Mahdi; Shekoohinejad, Hamidreza

2018-02-01

In this paper, temperature distribution in the continuous and pulsed end-pumped Nd:YAG rod crystal is determined using nonclassical and classical heat conduction theories. In order to find the temperature distribution in crystal, heat transfer differential equations of crystal with consideration of boundary conditions are derived based on non-Fourier's model and temperature distribution of the crystal is achieved by an analytical method. Then, by transferring non-Fourier differential equations to matrix equations, using finite element method, temperature and stress of every point of crystal are calculated in the time domain. According to the results, a comparison between classical and nonclassical theories is represented to investigate rupture power values. In continuous end pumping with equal input powers, non-Fourier theory predicts greater temperature and stress compared to Fourier theory. It also shows that with an increase in relaxation time, crystal rupture power decreases. Despite of these results, in single rectangular pulsed end-pumping condition, with an equal input power, Fourier theory indicates higher temperature and stress rather than non-Fourier theory. It is also observed that, when the relaxation time increases, maximum amounts of temperature and stress decrease.

Cryogenic heat transfer

CERN Document Server

Barron, Randall F

2016-01-01

Cryogenic Heat Transfer, Second Edition continues to address specific heat transfer problems that occur in the cryogenic temperature range where there are distinct differences from conventional heat transfer problems. This updated version examines the use of computer-aided design in cryogenic engineering and emphasizes commonly used computer programs to address modern cryogenic heat transfer problems. It introduces additional topics in cryogenic heat transfer that include latent heat expressions; lumped-capacity transient heat transfer; thermal stresses; Laplace transform solutions; oscillating flow heat transfer, and computer-aided heat exchanger design. It also includes new examples and homework problems throughout the book, and provides ample references for further study.

Socioeconomic Status, Subjective Social Status, and Perceived Stress: Associations with Stress Physiology and Executive Functioning.

Science.gov (United States)

Ursache, Alexandra; Noble, Kimberly G; Blair, Clancy

2015-01-01

Several studies have investigated associations between socioeconomic status (SES) and indicators of children's physiological and cognitive self-regulation. Although objective measures of family SES may be good proxies for families' experiences of disadvantage, less is known about subjective aspects of families' experiences. We hypothesize that subjective social status (SSS) and perceived stress may be important independent predictors of children's stress physiology and executive functioning (EF). Eighty-two children from diverse SES backgrounds were administered EF measures and provided saliva samples for cortisol assay. Caregivers reported on objective SES, SSS, and perceived stress. Results suggest that SES and SSS are both independently and positively related to EF. In models predicting stress physiology, higher perceived stress was associated with lower baseline cortisol. Moreover, SES and age interacted to predict cortisol levels such that among younger children, lower SES was associated with higher cortisol, whereas among older children, lower SES was associated with lower cortisol. Results highlight the importance of considering both objective and subjective indicators of families' SES and stressful experiences in relation to multiple aspects of children's self-regulation.

Functional outcome and quality of life after traumatic total brachial plexus injury treated by nerve transfer or single/double free muscle transfers: a comparative study.

Science.gov (United States)

Satbhai, N G; Doi, K; Hattori, Y; Sakamoto, S

2016-02-01

Between 2002 and 2011, 81 patients with a traumatic total brachial plexus injury underwent reconstruction by double free muscle transfer (DFMT, 47 cases), single muscle transfer (SMT, 16 cases) or nerve transfers (NT, 18 cases). They were evaluated for functional outcome and quality of life (QoL) using the Disability of Arm, Shoulder and Hand questionnaire, both pre- and post-operatively. The three groups were compared and followed-up for at least 24 months. The mean shoulder abduction and flexion were comparable in all groups, but external rotation was significantly better in the DFMT group as were range and quantitative power of elbow flexion. Patients who had undergone DFMT had reasonable total active finger movement and hook grip strength. All groups showed improvement in function at a level greater than a minimum clinically important difference. The DFMT group showed the greatest improvement. Patients in the DFMT group had a better functional outcome and QoL recovery than those in the NT and SMT groups. Double free muscle transfer procedure is capable of restoring maximum function in patients of total brachial plexus palsy. ©2016 The British Editorial Society of Bone & Joint Surgery.

Comprehensive functional analysis of Mycobacterium tuberculosis toxin-antitoxin systems: implications for pathogenesis, stress responses, and evolution.

Directory of Open Access Journals (Sweden)

Holly R Ramage

2009-12-01

Full Text Available Toxin-antitoxin (TA systems, stress-responsive genetic elements ubiquitous in microbial genomes, are unusually abundant in the major human pathogen Mycobacterium tuberculosis. Why M. tuberculosis has so many TA systems and what role they play in the unique biology of the pathogen is unknown. To address these questions, we have taken a comprehensive approach to identify and functionally characterize all the TA systems encoded in the M. tuberculosis genome. Here we show that 88 putative TA system candidates are present in M. tuberculosis, considerably more than previously thought. Comparative genomic analysis revealed that the vast majority of these systems are conserved in the M. tuberculosis complex (MTBC, but largely absent from other mycobacteria, including close relatives of M. tuberculosis. We found that many of the M. tuberculosis TA systems are located within discernable genomic islands and were thus likely acquired recently via horizontal gene transfer. We discovered a novel TA system located in the core genome that is conserved across the genus, suggesting that it may fulfill a role common to all mycobacteria. By expressing each of the putative TA systems in M. smegmatis, we demonstrate that 30 encode a functional toxin and its cognate antitoxin. We show that the toxins of the largest family of TA systems, VapBC, act by inhibiting translation via mRNA cleavage. Expression profiling demonstrated that four systems are specifically activated during stresses likely encountered in vivo, including hypoxia and phagocytosis by macrophages. The expansion and maintenance of TA genes in the MTBC, coupled with the finding that a subset is transcriptionally activated by stress, suggests that TA systems are important for M. tuberculosis pathogenesis.

Polyamines Function in Stress Tolerance: From Synthesis to Regulation

Directory of Open Access Journals (Sweden)

Ji-Hong eLiu

2015-10-01

Full Text Available Plants are challenged by a variety of biotic or abiotic stresses, which can affect their growth and development, productivity and geographic distribution. In order to survive adverse environmental conditions, plants have evolved various adaptive strategies, among which is the accumulation of metabolites that play protective roles. A well-established example of the metabolites that are involved in stress responses, or stress tolerance, is the low-molecular-weight aliphatic polyamines, including putrescine,spermidine and spermine. The critical role of polyamines in stress tolerance is suggested by several lines of evidence: firstly, the transcript levels of polyamine biosynthetic genes, as well as the activities of the corresponding enzymes, are induced by stresses; secondly, elevation of endogenous polyamine levels by exogenous supply of polyamines, or overexpression of polyamine biosynthetic genes, results in enhanced stress tolerance; and thirdly, a reduction of endogenous polyamines is accompanied by compromised stress tolerance. A number of studies have demonstrated that polyamines function in stress tolerance largely by modulating the homeostasis of reactive oxygen species (ROS due to their direct, or indirect, roles in regulating antioxidant systems or suppressing ROS production. The transcriptional regulation of polyamine synthesis by transcription factors is also reviewed here. Meanwhile, future perspectives on polyamine research are also suggested.

Investigation of a frequency dependent transfer function and its application to control rod localization

International Nuclear Information System (INIS)

Garis, N.S.; Pazsit, I.

1997-02-01

Control rod vibrations can be detected via the fluctuations they generate in the neutron flux, i.e. the neutron noise. In a previous paper, a neural network-based algorithm for locating a vibrating control rod from the measured neutron noise was developed. The transfer function used for the core model was based on the so called power-reactor approximation resulting in a simple, real-valued solution which means that the phase delay of the signal propagation is neglected. In the present work a more realistic transfer function is used, without the approximations of the previous model. The transfer function is calculated from the Fourier transformed diffusion equation with a complex, frequency dependent buckling leading to a complex solution. In physical terms, this means that the phase delay of the signal propagation is accounted for. Using such a complex core model, the present paper investigates the effectiveness of applying neural networks for control rod localisation. 7 refs, 4 figs

Determination of noise sources and space-dependent reactor transfer functions from measured output signals only

Energy Technology Data Exchange (ETDEWEB)

Hoogenboom, J.E.; van Dam, H.; Kleiss, E.B.J.; van Uitert, G.C.; Veldhuis, D.

1982-01-01

The measured cross power spectral densities of the signals from three neutron detectors and the displacement of the control rod of the 2 MW research reactor HOR at Delft have been used to determine the space-dependent reactor transfer function, the transfer function of the automatic reactor control system and the noise sources influencing the measured signals. From a block diagram of the reactor with control system and noise sources expressions were derived for the measured cross power spectral densities, which were adjusted to satisfy the requirements following from the adopted model. Then for each frequency point the required transfer functions and noise sources could be derived. The results are in agreement with those of autoregressive modelling of the reactor control feed-back loop. A method has been developed to determine the non-linear characteristics of the automatic reactor control system by analysing the non-gaussian probability density function of the power fluctuations.

Determination of noise sources and space-dependent reactor transfer functions from measured output signals only

International Nuclear Information System (INIS)

Hoogenboom, J.E.

1982-01-01

The measured cross power spectral densities of the signals from three neutron detectors and the displacement of the control rod of the 2 MW research reactor HOR at Delft have been used to determine the space-dependent reactor transfer function, the transfer function of the automatic reactor control system and the noise sources influencing the measured signals. From a block diagram of the reactor with control system and noise sources expressions were derived for the measured cross power spectral densities, which were adjusted to satisfy the requirements following from the adopted model. Then for each frequency point the required transfer functions and noise sources could be derived. The results are in agreement with those of autoregressive modelling of the reactor control feed-back loop. A method has been developed to determine the non-linear characteristics of the automatic reactor control system by analysing the non-gaussian probability density function of the power fluctuations. (author)

Life stress versus traumatic stress: The impact of life events on psychological functioning in children with and without serious illness.

Science.gov (United States)

Willard, Victoria W; Long, Alanna; Phipps, Sean

2016-01-01

To determine the differential impact of potentially traumatic events (PTEs) and other stressful life events on psychological functioning in 2 groups of children: those with cancer and those without history of serious illness. Children with cancer age 8-17 (n = 254) and age-, sex-, and race/ethnicity-matched controls (n = 142) completed self-report measures of stressful life events and psychological functioning. Stressful life events included those that may meet Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 2000) A1 criteria (PTEs; 9 events) and others that would likely not (other events; 21 events). Children with cancer endorsed significantly more PTEs than control children. There were no differences between groups in number of other events experienced. Hierarchical regression analyses revealed that number of other events accounted for significant variance in psychological functioning, above and beyond group status, demographic factors (age and socioeconomic status), and number of PTEs. The number of cumulative other events experienced is a significant predictor of psychological functioning in both youth with serious illness and controls. In contrast, cumulative PTEs appear to have a minor (albeit significant) impact on children's psychological functioning. Assessment of psychological functioning would benefit from a thorough history of stressful life events, regardless of their potential traumatic impact. (c) 2016 APA, all rights reserved).

Aroma Effects on Physiologic and Cognitive Function Following Acute Stress: A Mechanism Investigation

OpenAIRE

Chamine, Irina; Oken, Barry S.

2016-01-01

Objective: Aromas may improve physiologic and cognitive function after stress, but associated mechanisms remain unknown. This study evaluated the effects of lavender aroma, which is commonly used for stress reduction, on physiologic and cognitive functions. The contribution of pharmacologic, hedonic, and expectancy-related mechanisms of the aromatherapy effects was evaluated.

Functional brain asymmetry, attentional modulation, and interhemispheric transfer in boys with Tourette syndrome

DEFF Research Database (Denmark)

Plessen, Kerstin J; Lundervold, Arvid; Grüner, Renate

2007-01-01

on the right ear stimulus in the dichotic listening situation is thought to involve the same prefrontal attentional and executive functions that are involved in the suppression of tics, whereas, performance when focusing attention on the left ear stimulus additionally involves a callosal transfer...... to shift attention normally when instructed to focus on the right ear stimulus. When instructed to focus attention on the left ear stimulus, however, performance deteriorated in the TS group. Correlations with CC area further supported the hypothesized presence of deviant callosal functioning in the TS...... of information. In light of presumed disturbances in transfer of information across the corpus callosum, we hypothesized that children with TS would, however, have difficulty modulating the functional lateralization that ensues through a shift of attention to the left side. This hypothesis was tested...

Green's Function and Stress Fields in Stochastic Heterogeneous Continua

Science.gov (United States)

Negi, Vineet

Many engineering materials used today are heterogenous in composition e.g. Composites - Polymer Matrix Composites, Metal Matrix Composites. Even, conventional engineering materials - metals, plastics, alloys etc. - may develop heterogeneities, like inclusions and residual stresses, during the manufacturing process. Moreover, these materials may also have intrinsic heterogeneities at a nanoscale in the form of grain boundaries in metals, crystallinity in amorphous polymers etc. While, the homogenized constitutive models for these materials may be satisfactory at a macroscale, recent studies of phenomena like fatigue failure, void nucleation, size-dependent brittle-ductile transition in polymeric nanofibers reveal a major play of micro/nanoscale physics in these phenomena. At this scale, heterogeneities in a material may no longer be ignored. Thus, this demands a study into the effects of various material heterogeneities. In this work, spatial heterogeneities in two material properties - elastic modulus and yield stress - have been investigated separately. The heterogeneity in the elastic modulus is studied in the context of Green's function. The Stochastic Finite Element method is adopted to get the mean statistics of the Green's function defined on a stochastic heterogeneous 2D infinite space. A study of the elastic-plastic transition in a domain having stochastic heterogenous yield stress was done using Mont-Carlo methods. The statistics for various stress and strain fields during the transition were obtained. Further, the effects of size of the domain and the strain-hardening rate on the stress fields during the heterogeneous elastic-plastic transition were investigated. Finally, a case is made for the role of the heterogenous elastic-plastic transition in damage nucleation and growth.

Effects of source and receiver locations in predicting room transfer functions by a phased beam tracing method

DEFF Research Database (Denmark)

Jeong, Cheol-Ho; Ih, Jeong-Guon

2012-01-01

The accuracy of a phased beam tracing method in predicting transfer functions is investigated with a special focus on the positions of the source and receiver. Simulated transfer functions for various source-receiver pairs using the phased beam tracing method were compared with analytical Green’s...

The Use of Nerve Transfers to Restore Upper Extremity Function in Cervical Spinal Cord Injury.

Science.gov (United States)

Fox, Ida K; Novak, Christine B; Krauss, Emily M; Hoben, Gwendolyn M; Zaidman, Craig; Ruvinskaya, Rimma; Juknis, Neringa; Winter, Anke C; Mackinnon, Susan E

2018-03-15

Nerve transfer surgery to restore upper extremity function in cervical spinal cord injury (SCI) is novel and may transform treatment. Determining candidacy even years post-SCI is ill defined and deserves investigation. To develop a diagnostic algorithm, focusing on electrodiagnostic (EDX) studies, to determine eligibility for nerve transfer surgery. Retrospective descriptive case series. Tertiary university-based institution. Individuals with cervical SCI (n = 45). The electronic medical records of people referred to the Plastic Surgery Multidisciplinary Upper Extremity Surgery unit in the SCI clinic from 2010-2015 were reviewed. People were considered for nerve transfers to restore elbow extension or finger flexion and/or extension. Data including demographic, clinical evaluation, EDX results, surgery, and outcomes were collected and analyzed. EDX data, including nerve conduction studies and electromyography, for bilateral upper extremities of each patient examined was used to assess for the presence of lower motor neuron injury, which would preclude late nerve transfer. Based on our criteria and the results of EDX testing, a substantial number of patients presenting even years post-SCI were candidates for nerve transfers. Clinical outcome results are heterogeneous but promising and suggest that further refinement of eligibility, long-term follow-up, and standardized assessment will improve our understanding of the role of nerve transfer surgery to restore function in people with midcervical SCI. Many patients living with SCI are candidates for nerve transfer surgery to restore upper extremity function. Although the ultimate efficacy of these surgeries is not yet determined, this study attempts to report the criteria we are using and may ultimately determine the timing for intervention and which transfers are most useful for this heterogeneous population. IV. Copyright © 2018 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All

Transference of function shapes organ identity in the dove tree inflorescence.

Science.gov (United States)

Vekemans, Dries; Viaene, Tom; Caris, Pieter; Geuten, Koen

2012-01-01

• An important evolutionary mechanism shaping the biodiversity of flowering plants is the transfer of function from one plant organ to another. To investigate whether and how transference of function is associated with the remodeling of the floral organ identity program we studied Davidia involucrata, a species with conspicuous, petaloid bracts subtending a contracted inflorescence with reduced flowers. • A detailed ontogeny enabled the interpretation of expression patterns of B-, C- and E-class homeotic MADS-box genes using qRT-PCR and in situ hybridization techniques. We investigated protein-protein interactions using yeast two-hybrid assays. • Although loss of organs does not appear to have affected organ identity in the retained organs of the reduced flowers of D. involucrata, the bracts express the B-class TM6 (Tomato MADS box gene 6) and GLOBOSA homologs, but not DEFICIENS, and the C-class AGAMOUS homolog, representing a subset of genes also involved in stamen identity. • Our results may illustrate how petal identity can be partially transferred outside the flower by expressing a subset of stamen identity genes. This adds to the molecular mechanisms explaining the diversity of plant reproductive morphology. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Effect of Chronic Social Stress on Prenatal Transfer of Antitetanus Immunity in Captive Breeding Rhesus Macaques (Macaca mulatta).

Science.gov (United States)

Stammen, Rachelle L; Cohen, Joyce K; Meeker, Tracy L; Crane, Maria M; Amara, Rama R; Hicks, Sakeenah L; Meyer, Jerrold S; Ethun, Kelly F

2018-05-15

Because tetanus can cause significant morbidity and mortality in NHP, colonywide vaccination with tetanus toxoid is recommendedfor outdoor breeding colonies of rhesus macaques, with primary immunizations commonly given to infants at 6 mo of age followed by booster vaccines every 10 y. Maternal antibodies are thought to offer protective immunity to infants younger than 6 mo. However, historical colony data from the Yerkes National Primate Research Center show a higher incidence of tetanus among infants (≤ 6 mo old) born to subordinate dams. Whether this higher incidence of infantile tetanus is due to a higher incidence of trauma among subordinate animals or is a stress-induced impairment of maternal antibody protection is unknown. Studies in other NHP species suggest that chronic exposure to social stressors interferes with the receptor-mediated transplacental transfer of IgG. Therefore, the primary aim of this study was to determine whether chronic stress associated with social subordination impairs prenatal transfer of antitetanus immunity in breeding female rhesus macaques. Subjects included 26 high- and 26 low-ranking adult female rhesus macaques that were nearly 5 or 10 y after their initial immunization and their nonimmunized infants. We hypothesized that infants born to subordinate dams that were nearly 10 y after immunization would have the lowest infant-to-dam antibody ratios and thus would be at greatest risk for infection. Results revealed no significant intergroup differences in infant antitetanus IgG levels. However, infant-to-dam IgG ratios against tetanus were significantly lower among subordinate animals compared with dominant macaques, after accounting for the number of years since the dam's initial vaccination. In addition, higher maternal hair cortisol levels predicted lower infant-to-dam tetanus toxoid IgG ratios. Together, these findings suggest that chronic social stress in female rhesus macaques may hamper the prenatal transfer of

Integration of Heat Transfer, Stress, and Particle Trajectory Simulation. Final report

International Nuclear Information System (INIS)

Bui, Thuc; Read, Michael; Ives, Lawrence

2012-01-01

Calabazas Creek Research, Inc. developed and currently markets Beam Optics Analyzer (BOA) in the United States and abroad. BOA is a 3D, charged particle optics code that solves the electric and magnetic fields with and without the presence of particles. It includes automatic and adaptive meshing to resolve spatial scales ranging from a few millimeters to meters. It is fully integrated with CAD packages, such as SolidWorks, allowing seamless geometry updates. The code includes iterative procedures for optimization, including a fully functional, graphical user interface. Recently, time dependent, particle in cell capability was added, pushing particles synchronically under quasistatic electromagnetic fields to obtain particle bunching under RF conditions. A heat transfer solver was added during this Phase I program. Completed tasks include: (1) Added a 3D finite element heat transfer solver with adaptivity; (2) Determined the accuracy of the linear heat transfer field solver to provide the basis for development of higher order solvers in Phase II; (3) Provided more accurate and smoother power density fields; and (4) Defined the geometry using the same CAD model, while maintaining different meshes, and interfacing the power density field between the particle simulator and heat transfer solvers. These objectives were achieved using modern programming techniques and algorithms. All programming was in C++ and parallelization in OpenMP, utilizing state-of-the-art multi-core technology. Both x86 and x64 versions are supported. The GUI design and implementation used Microsoft Foundation Class.

The Effects of Acute Stress on Core Executive Functions: A Meta-Analysis and Comparison with Cortisol

Science.gov (United States)

Shields, Grant S.; Sazma, Matthew A.; Yonelinas, Andrew P.

2016-01-01

Core executive functions such as working memory, inhibition, and cognitive flexibility are integral to daily life. A growing body of research has suggested that acute stress may impair core executive functions. However, there are a number of inconsistencies in the literature, leading to uncertainty about how or even if acute stress influences core executive functions. We addressed this by conducting a meta-analysis of acute stress effects on working memory, inhibition, and cognitive flexibility. We found that stress impaired working memory and cognitive flexibility, whereas it had nuanced effects on inhibition. Many of these effects were moderated by other variables, such as sex. In addition, we compared effects of acute stress on core executive functions to effects of cortisol administration and found some striking differences. Our findings indicate that stress works through mechanisms aside from or in addition to cortisol to produce a state characterized by more reactive processing of salient stimuli but greater control over actions. We conclude by highlighting some important future directions for stress and executive function research. PMID:27371161

Impaired Functional Connectivity in the Prefrontal Cortex: A Mechanism for Chronic Stress-Induced Neuropsychiatric Disorders

Directory of Open Access Journals (Sweden)

Ignacio Negrón-Oyarzo

2016-01-01

Full Text Available Chronic stress-related psychiatric diseases, such as major depression, posttraumatic stress disorder, and schizophrenia, are characterized by a maladaptive organization of behavioral responses that strongly affect the well-being of patients. Current evidence suggests that a functional impairment of the prefrontal cortex (PFC is implicated in the pathophysiology of these diseases. Therefore, chronic stress may impair PFC functions required for the adaptive orchestration of behavioral responses. In the present review, we integrate evidence obtained from cognitive neuroscience with neurophysiological research with animal models, to put forward a hypothesis that addresses stress-induced behavioral dysfunctions observed in stress-related neuropsychiatric disorders. We propose that chronic stress impairs mechanisms involved in neuronal functional connectivity in the PFC that are required for the formation of adaptive representations for the execution of adaptive behavioral responses. These considerations could be particularly relevant for understanding the pathophysiology of chronic stress-related neuropsychiatric disorders.

Aroma Effects on Physiologic and Cognitive Function Following Acute Stress: A Mechanism Investigation.

Science.gov (United States)

Chamine, Irina; Oken, Barry S

2016-09-01

Aromas may improve physiologic and cognitive function after stress, but associated mechanisms remain unknown. This study evaluated the effects of lavender aroma, which is commonly used for stress reduction, on physiologic and cognitive functions. The contribution of pharmacologic, hedonic, and expectancy-related mechanisms of the aromatherapy effects was evaluated. Ninety-two healthy adults (mean age, 58.0 years; 79.3% women) were randomly assigned to three aroma groups (lavender, perceptible placebo [coconut], and nonperceptible placebo [water] and to two prime subgroups (primed, with a suggestion of inhaling a powerful stress-reducing aroma, or no prime). Participants' performance on a battery of cognitive tests, physiologic responses, and subjective stress were evaluated at baseline and after exposure to a stress battery during which aromatherapy was present. Participants also rated the intensity and pleasantness of their assigned aroma. Pharmacologic effects of lavender but not placebo aromas significantly benefited post-stress performance on the working memory task (F(2, 86) = 5.41; p = 0.006). Increased expectancy due to positive prime, regardless of aroma type, facilitated post-stress performance on the processing speed task (F(1, 87) = 8.31; p = 0.005). Aroma hedonics (pleasantness and intensity) played a role in the beneficial lavender effect on working memory and physiologic function. The observable aroma effects were produced by a combination of mechanisms involving aroma-specific pharmacologic properties, aroma hedonic properties, and participant expectations. In the future, each of these mechanisms could be manipulated to produce optimal functioning.

A dependent stress-strength interference model based on mixed copula function

Energy Technology Data Exchange (ETDEWEB)

Gao, Jian Xiong; An, Zong Wen; Liu, Bo [School of Mechatronics Engineering, Lanzhou University of Technology, Lanzhou (China)

2016-10-15

In the traditional Stress-strength interference (SSI) model, stress and strength must satisfy the basic assumption of mutual independence. However, a complex dependence between stress and strength exists in practical engineering. To evaluate structural reliability under the case that stress and strength are dependent, a mixed copula function is introduced to a new dependent SSI model. This model can fully characterize the dependence between stress and strength. The residual square sum method and genetic algorithm are also used to estimate the unknown parameters of the model. Finally, the validity of the proposed model is demonstrated via a practical case. Results show that traditional SSI model ignoring the dependence between stress and strength more easily overestimates product reliability than the new dependent SSI model.

A spatial compression technique for head-related transfer function interpolation and complexity estimation

DEFF Research Database (Denmark)

Shekarchi, Sayedali; Christensen-Dalsgaard, Jakob; Hallam, John

2015-01-01

A head-related transfer function (HRTF) model employing Legendre polynomials (LPs) is evaluated as an HRTF spatial complexity indicator and interpolation technique in the azimuth plane. LPs are a set of orthogonal functions derived on the sphere which can be used to compress an HRTF dataset...

Thick film laser induced forward transfer for deposition of thermally and mechanically sensitive materials

International Nuclear Information System (INIS)

Kattamis, Nicholas T.; Purnick, Priscilla E.; Weiss, Ron; Arnold, Craig B.

2007-01-01

Laser forward transfer processes incorporating thin absorbing films can be used to deposit robust organic and inorganic materials but the deposition of more delicate materials has remained elusive due to contamination and stress induced during the transfer process. Here, we present the approach to high resolution patterning of sensitive materials by incorporating a thick film polymer absorbing layer that is able to dissipate shock energy through mechanical deformation. Multiple mechanisms for transfer as a function of incident laser energy are observed and we show viable and contamination-free deposition of living mammalian embryonic stem cells

Stress and resilience in functional somatic syndromes--a structural equation modeling approach.

Directory of Open Access Journals (Sweden)

Susanne Fischer

Full Text Available BACKGROUND: Stress has been suggested to play a role in the development and perpetuation of functional somatic syndromes. The mechanisms of how this might occur are not clear. PURPOSE: We propose a multi-dimensional stress model which posits that childhood trauma increases adult stress reactivity (i.e., an individual's tendency to respond strongly to stressors and reduces resilience (e.g., the belief in one's competence. This in turn facilitates the manifestation of functional somatic syndromes via chronic stress. We tested this model cross-sectionally and prospectively. METHODS: Young adults participated in a web survey at two time points. Structural equation modeling was used to test our model. The final sample consisted of 3'054 participants, and 429 of these participated in the follow-up survey. RESULTS: Our proposed model fit the data in the cross-sectional (χ2(21  = 48.808, p<.001, CFI  = .995, TLI  = .992, RMSEA  = .021, 90% CI [.013.029] and prospective analyses (χ2(21  =  32.675, p<.05, CFI  = .982, TLI  = .969, RMSEA  = .036, 90% CI [.001.059]. DISCUSSION: Our findings have several clinical implications, suggesting a role for stress management training in the prevention and treatment of functional somatic syndromes.

Effects of stress on immune function: the good, the bad, and the beautiful.

Science.gov (United States)

Dhabhar, Firdaus S

2014-05-01

Although the concept of stress has earned a bad reputation, it is important to recognize that the adaptive purpose of a physiological stress response is to promote survival during fight or flight. While long-term stress is generally harmful, short-term stress can be protective as it prepares the organism to deal with challenges. This review discusses the immune effects of biological stress responses that can be induced by psychological, physiological, or physical (including exercise) stressors. We have proposed that short-term stress is one of the nature's fundamental but under-appreciated survival mechanisms that could be clinically harnessed to enhance immunoprotection. Short-term (i.e., lasting for minutes to hours) stress experienced during immune activation enhances innate/primary and adaptive/secondary immune responses. Mechanisms of immuno-enhancement include changes in dendritic cell, neutrophil, macrophage, and lymphocyte trafficking, maturation, and function as well as local and systemic production of cytokines. In contrast, long-term stress suppresses or dysregulates innate and adaptive immune responses by altering the Type 1-Type 2 cytokine balance, inducing low-grade chronic inflammation, and suppressing numbers, trafficking, and function of immunoprotective cells. Chronic stress may also increase susceptibility to some types of cancer by suppressing Type 1 cytokines and protective T cells and increasing regulatory/suppressor T cell function. Here, we classify immune responses as being protective, pathological, or regulatory, and discuss "good" versus "bad" effects of stress on health. Thus, short-term stress can enhance the acquisition and/or expression of immunoprotective (wound healing, vaccination, anti-infectious agent, anti-tumor) or immuno-pathological (pro-inflammatory, autoimmune) responses. In contrast, chronic stress can suppress protective immune responses and/or exacerbate pathological immune responses. Studies such as the ones discussed

Modulation Transfer Function of Infrared Focal Plane Arrays

Science.gov (United States)

Gunapala, S. D.; Rafol, S. B.; Ting, D. Z.; Soibel, A.; Hill, C. J.; Khoshakhlagh, A.; Liu, J. K.; Mumolo, J. M.; Hoglund, L.; Luong, E. M.

2015-01-01

Modulation transfer function (MTF) is the ability of an imaging system to faithfully image a given object. The MTF of an imaging system quantifies the ability of the system to resolve or transfer spatial frequencies. In this presentation we will discuss the detail MTF measurements of 1024x1024 pixels mid -wavelength and long- wavelength quantum well infrared photodetector, and 320x256 pixels long- wavelength InAs/GaSb superlattice infrared focal plane arrays (FPAs). Long wavelength Complementary Barrier Infrared Detector (CBIRD) based on InAs/GaSb superlattice material is hybridized to recently designed and fabricated 320x256 pixel format ROIC. The n-type CBIRD was characterized in terms of performance and thermal stability. The experimentally measured NE delta T of the 8.8 micron cutoff n-CBIRD FPA was 18.6 mK with 300 K background and f/2 cold stop at 78K FPA operating temperature. The horizontal and vertical MTFs of this pixel fully delineated CBIRD FPA at Nyquist frequency are 49% and 52%, respectively.

Linear and Non-Linear Dose-Response Functions Reveal a Hormetic Relationship Between Stress and Learning

OpenAIRE

Zoladz, Phillip R.; Diamond, David M.

2008-01-01

Over a century of behavioral research has shown that stress can enhance or impair learning and memory. In the present review, we have explored the complex effects of stress on cognition and propose that they are characterized by linear and non-linear dose-response functions, which together reveal a hormetic relationship between stress and learning. We suggest that stress initially enhances hippocampal function, resulting from amygdala-induced excitation of hippocampal synaptic plasticity, as ...

Hypothalamic-pituitary-adrenal axis genetic variation and early stress moderates amygdala function.

Science.gov (United States)

Di Iorio, Christina R; Carey, Caitlin E; Michalski, Lindsay J; Corral-Frias, Nadia S; Conley, Emily Drabant; Hariri, Ahmad R; Bogdan, Ryan

2017-06-01

Early life stress may precipitate psychopathology, at least in part, by influencing amygdala function. Converging evidence across species suggests that links between childhood stress and amygdala function may be dependent upon hypothalamic-pituitary-adrenal (HPA) axis function. Using data from college-attending non-Hispanic European-Americans (n=308) who completed the Duke Neurogenetics Study, we examined whether early life stress (ELS) and HPA axis genetic variation interact to predict threat-related amygdala function as well as psychopathology symptoms. A biologically-informed multilocus profile score (BIMPS) captured HPA axis genetic variation (FKBP5 rs1360780, CRHR1 rs110402; NR3C2 rs5522/rs4635799) previously associated with its function (higher BIMPS are reflective of higher HPA axis activity). BOLD fMRI data were acquired while participants completed an emotional face matching task. ELS and depression and anxiety symptoms were measured using the childhood trauma questionnaire and the mood and anxiety symptom questionnaire, respectively. The interaction between HPA axis BIMPS and ELS was associated with right amygdala reactivity to threat-related stimuli, after accounting for multiple testing (empirical-p=0.016). Among individuals with higher BIMPS (i.e., the upper 21.4%), ELS was positively coupled with threat-related amygdala reactivity, which was absent among those with average or low BIMPS. Further, higher BIMPS were associated with greater self-reported anxious arousal, though there was no evidence that amygdala function mediated this relationship. Polygenic variation linked to HPA axis function may moderate the effects of early life stress on threat-related amygdala function and confer risk for anxiety symptomatology. However, what, if any, neural mechanisms may mediate the relationship between HPA axis BIMPS and anxiety symptomatology remains unclear. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

Science.gov (United States)

Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

2018-06-01

Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

Non-invasive baroreflex sensitivity assessment using wavelet transfer function-based time–frequency analysis

International Nuclear Information System (INIS)

Keissar, K; Gilad, O; Maestri, R; Pinna, G D; La Rovere, M T

2010-01-01

A novel approach for the estimation of baroreflex sensitivity (BRS) is introduced based on time–frequency analysis of the transfer function (TF). The TF method (TF-BRS) is a well-established non-invasive technique which assumes stationarity. This condition is difficult to meet, especially in cardiac patients. In this study, the classical TF was replaced with a wavelet transfer function (WTF) and the classical coherence was replaced with wavelet transform coherence (WTC), adding the time domain as an additional degree of freedom with dynamic error estimation. Error analysis and comparison between WTF-BRS and TF-BRS were performed using simulated signals with known transfer function and added noise. Similar comparisons were performed for ECG and blood pressure signals, in the supine position, of 19 normal subjects, 44 patients with a history of previous myocardial infarction (MI) and 45 patients with chronic heart failure. This yielded an excellent linear association (R > 0.94, p < 0.001) for time-averaged WTF-BRS, validating the new method as consistent with a known method. The additional advantage of dynamic analysis of coherence and TF estimates was illustrated in two physiological examples of supine rest and change of posture showing the evolution of BRS synchronized with its error estimations and sympathovagal balance

Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction

Science.gov (United States)

McLaskey, Gregory Christofer

Rapidly varying forces, such as those associated with impact, rapid crack propagation, and fault rupture, are sources of stress waves which propagate through a solid body. This dissertation investigates how properties of a stress wave source can be identified or constrained using measurements recorded at an array of sensor sites located far from the source. This methodology is often called the method of acoustic emission and is useful for structural health monitoring and the noninvasive study of material behavior such as friction and fracture. In this dissertation, laboratory measurements of 1--300 mm wavelength stress waves are obtained by means of piezoelectric sensors which detect high frequency (10 kHz--3MHz) motions of a specimen's surface, picometers to nanometers in amplitude. Then, stress wave source characterization techniques are used to study ball impact, drying shrinkage cracking in concrete, and the micromechanics of stick-slip friction of Poly(methyl methacrylate) (PMMA) and rock/rock interfaces. In order to quantitatively relate recorded signals obtained with an array of sensors to a particular stress wave source, wave propagation effects and sensor distortions must be accounted for. This is achieved by modeling the physics of wave propagation and transduction as linear transfer functions. Wave propagation effects are precisely modeled by an elastodynamic Green's function, sensor distortion is characterized by an instrument response function, and the stress wave source is represented with a force moment tensor. These transfer function models are verified though calibration experiments which employ two different mechanical calibration sources: ball impact and glass capillary fracture. The suitability of the ball impact source model, based on Hertzian contact theory, is experimentally validated for small (˜1 mm) balls impacting massive plates composed of four different materials: aluminum, steel, glass, and PMMA. Using this transfer function approach

Oxidative stress induced inflammation initiates functional decline of tear production.

Directory of Open Access Journals (Sweden)

Yuichi Uchino

Full Text Available Oxidative damage and inflammation are proposed to be involved in an age-related functional decline of exocrine glands. However, the molecular mechanism of how oxidative stress affects the secretory function of exocrine glands is unclear. We developed a novel mev-1 conditional transgenic mouse model (Tet-mev-1 using a modified tetracycline system (Tet-On/Off system. This mouse model demonstrated decreased tear production with morphological changes including leukocytic infiltration and fibrosis. We found that the mev-1 gene encodes Cyt-1, which is the cytochrome b(560 large subunit of succinate-ubiquinone oxidoreductase in complex II of mitochondria (homologous to succinate dehydrogenase C subunit (SDHC in humans. The mev-1 gene induced excessive oxidative stress associated with ocular surface epithelial damage and a decrease in protein and aqueous secretory function. This new model provides evidence that mitochondrial oxidative damage in the lacrimal gland induces lacrimal dysfunction resulting in dry eye disease. Tear volume in Tet-mev-1 mice was lower than in wild type mice and histopathological analyses showed the hallmarks of lacrimal gland inflammation by intense mononuclear leukocytic infiltration and fibrosis in the lacrimal gland of Tet-mev-1 mice. These findings strongly suggest that oxidative stress can be a causative factor for the development of dry eye disease.

Ovarian transfer following irradiation as an alternative to restore reproductive functions

Energy Technology Data Exchange (ETDEWEB)

Salgado, Andreia Ruis; Passos, Luiz Augusto Correa; Ginemes, Ana Paula; Dias, Viviane Liotti [Universidade Estadual de Campinas, SP (Brazil). Centro Multidisciplinar para a Investigacao Biologica (CEMIB/UNICAMP)], e-mail: viviliotti@cemib.unicamp.br; Spencer, Patrick Jack; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)

2009-07-01

Assisted reproduction technologies are essential for restoring reproductive functions, especially in ovary cancer cases, which besides impairing fertility; present the highest lethality amongst gynecological diseases. Classical treatment involves surgery, radiotherapy and chemotherapy, and in young women, the recommended treatment is the removal of the affected ovary, leading to physical, psychological and emotional problems. An alternative would be the ovarian transfer after the treatment. However, there are no data in the literature about experiments specifically designed to investigate the interference of this procedure on reproductive functions. In the present work, we used the C57BL/6Unib and B6CF1 hybrid mice strains to evaluate the viability of ovarian transfer before and after irradiation, as well as possible differences in radiosensitivity between the strains. To do so, female mice from both strains were irradiated with 4 Gy and submitted to either partial or total ovarian transfer form healthy donors. After the surgery, the animals were mated and the results obtained so far for mating 7 days after the procedure indicate that irradiation promoted a significant decrease in fertility (p=0.0127). Also, our data show that the recovery of fertility is proportional to the amount of grafted ovarian tissue. Furthermore, there seems to be differences in radiosensitivity, from genetic origin, between the two mice strain, since, after irradiation, the hybrid mice had bigger litters than the donor strain. (author)

Ovarian transfer following irradiation as an alternative to restore reproductive functions

International Nuclear Information System (INIS)

Salgado, Andreia Ruis; Passos, Luiz Augusto Correa; Ginemes, Ana Paula; Dias, Viviane Liotti; Spencer, Patrick Jack; Nascimento, Nanci do

2009-01-01

Assisted reproduction technologies are essential for restoring reproductive functions, especially in ovary cancer cases, which besides impairing fertility; present the highest lethality amongst gynecological diseases. Classical treatment involves surgery, radiotherapy and chemotherapy, and in young women, the recommended treatment is the removal of the affected ovary, leading to physical, psychological and emotional problems. An alternative would be the ovarian transfer after the treatment. However, there are no data in the literature about experiments specifically designed to investigate the interference of this procedure on reproductive functions. In the present work, we used the C57BL/6Unib and B6CF1 hybrid mice strains to evaluate the viability of ovarian transfer before and after irradiation, as well as possible differences in radiosensitivity between the strains. To do so, female mice from both strains were irradiated with 4 Gy and submitted to either partial or total ovarian transfer form healthy donors. After the surgery, the animals were mated and the results obtained so far for mating 7 days after the procedure indicate that irradiation promoted a significant decrease in fertility (p=0.0127). Also, our data show that the recovery of fertility is proportional to the amount of grafted ovarian tissue. Furthermore, there seems to be differences in radiosensitivity, from genetic origin, between the two mice strain, since, after irradiation, the hybrid mice had bigger litters than the donor strain. (author)

Headphone-To-Ear Transfer Function Estimation Using Measured Acoustic Parameters

Directory of Open Access Journals (Sweden)

Jinlin Liu

2018-06-01

Full Text Available This paper proposes to use an optimal five-microphone array method to measure the headphone acoustic reflectance and equivalent sound sources needed in the estimation of headphone-to-ear transfer functions (HpTFs. The performance of this method is theoretically analyzed and experimentally investigated. With the measured acoustic parameters HpTFs for different headphones and ear canal area functions are estimated based on a computational acoustic model. The estimation results show that HpTFs vary considerably with headphones and ear canals, which suggests that individualized compensations for HpTFs are necessary for headphones to reproduce desired sounds for different listeners.

On the low frequency characteristics of head-related transfer function

Institute of Scientific and Technical Information of China (English)

XIE Bosun

2009-01-01

A method to correct the measured head-related transfer functions (HRTFs) at low frequency was proposed. By analyzing the HRTFs from the spherical head model at low frequency, it is proved that below the frequency of 400 Hz, magnitude of HRTF is nearly constant and the phase is a linear function of frequency both for the far and near field. Therefore, if the HRTFs above 400 Hz are accurately measured by experiment, it is able to correct the HRTFs at low frequency by the theoretical model. The results of calculation and subjective experiment show that the feasibility of the proposed method.

Corticosterone response to gestational stress and postpartum memory function in mice.

Science.gov (United States)

Jafari, Zahra; Mehla, Jogender; Afrashteh, Navvab; Kolb, Bryan E; Mohajerani, Majid H

2017-01-01

Maternal stress is a common adversity during pregnancy. Gestational corticosterone alternations are thought to contribute to the etiology of postpartum behavioral disturbances. However, the impact of stress during pregnancy, in particular noise exposure, on gestational corticosterone fluctuations and spatial cognition in postpartum mice has not been fully understood yet. We hypothesized that noise exposure during pregnancy negatively affects gestational corticosterone levels and postpartum memory function in the dams similar to the physical stressors. Pregnant C57BL/6 mice were randomly assigned to either one of two stress conditions or a control condition. The noise stress (NS) was induced by presenting a loud intermittent 3000 Hz frequency on gestational days (GDs) 12, 14, and 16 for 24 hours, whereas the physical stress (PS) consisted of restraint and exposure to an elevated platform on GDs 12-16. Plasma corticosterone level was collected on GDs 11 and 17, and Morris water task (MWT) was carried out 30 days after parturition. Compared to the control group, the level of corticosterone in the stressed groups was significantly increased on GD17 relative to GD11. Significantly longer swim time and lower swim speed were observed in both stressed groups relative to the control group. Probe time was significantly shorter in the NS group than the other groups. The delta corticosterone level was significantly correlated with the swim time as well as the probe time in the three groups. Given the results, the adverse effects of gestational noise exposure on the hypothalamic pituitary-adrenal (HPA) axis activation and postpartum spatial learning and memory function were as large as/ or a bit stronger than the physical stresses. The findings suggest the significance of conservation against loud noise exposure in daily living, as well as need to further notice to the different aspects of gestational stress in mothers' behavior like offspring.

Thermal Stress and Heat Transfer Coefficient for Ceramics Stalk Having Protuberance Dipping into Molten Metal

Science.gov (United States)

Noda, Nao-Aki; Hendra; Li, Wenbin; Takase, Yasushi; Ogura, Hiroki; Higashi, Yusuke

Low pressure die casting is defined as a net shape casting technology in which the molten metal is injected at high speeds and pressure into a metallic die. The low pressure die casting process plays an increasingly important role in the foundry industry as a low-cost and high-efficiency precision forming technique. In the low pressure die casting process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal, by means of a pressurized gas, to rise into a ceramic tube having protuberance, which connects the die to the furnace. The ceramics tube, called stalk, has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the stalk having protuberance is dipped into the molten aluminum. It is important to reduce the risk of fracture that may happen due to the thermal stresses. In this paper, thermo-fluid analysis is performed to calculate surface heat transfer coefficient. The finite element method is applied to calculate the thermal stresses when the stalk having protuberance is dipped into the crucible with varying dipping speeds. It is found that the stalk with or without protuberance should be dipped into the crucible slowly to reduce the thermal stress.

TRANSFERENCE BEFORE TRANSFERENCE.

Science.gov (United States)

Bonaminio, Vincenzo

2017-10-01

This paper is predominantly a clinical presentation that describes the transmigration of one patient's transference to another, with the analyst functioning as a sort of transponder. It involves an apparently accidental episode in which there was an unconscious intersection between two patients. The author's aim is to show how transference from one case may affect transference in another, a phenomenon the author calls transference before transference. The author believes that this idea may serve as a tool for understanding the unconscious work that takes place in the clinical situation. In a clinical example, the analyst finds himself caught up in an enactment involving two patients in which he becomes the medium of what happens in session. © 2017 The Psychoanalytic Quarterly, Inc.

Conjugative Plasmid Transfer in Xylella fastidiosa Is Dependent on tra and trb Operon Functions.

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Burbank, Lindsey P; Van Horn, Christopher R

2017-11-01

The insect-transmitted plant pathogen Xylella fastidiosa is capable of efficient horizontal gene transfer (HGT) and recombination. Natural transformation occurs at high rates in X. fastidiosa , but there also is evidence that certain strains of X. fastidiosa carry native plasmids equipped with transfer and mobilization genes, suggesting conjugation as an additional mechanism of HGT in some instances. Two operons, tra and trb , putatively encoding a conjugative type IV secretion system, are found in some but not all X. fastidiosa isolates, often on native plasmids. X. fastidiosa strains that carry the conjugative transfer genes can belong to different subspecies and frequently differ in host ranges. Using X. fastidiosa strain M23 ( X. fastidiosa subsp. fastidiosa ) or Dixon ( X. fastidiosa subsp. multiplex ) as the donor strain and Temecula ( X. fastidiosa subsp. fastidiosa ) as the recipient strain, plasmid transfer was characterized using the mobilizable broad-host-range vector pBBR5pemIK. Transfer of plasmid pBBR5pemIK was observed under in vitro conditions with both donor strains and was dependent on both tra and trb operon functions. A conjugative mechanism likely contributes to gene transfer between diverse strains of X. fastidiosa , possibly facilitating adaptation to new environments or different hosts. IMPORTANCE Xylella fastidiosa is an important plant pathogen worldwide, infecting a wide range of different plant species. The emergence of new diseases caused by X. fastidiosa , or host switching of existing strains, is thought to be primarily due to the high frequency of HGT and recombination in this pathogen. Transfer of plasmids by a conjugative mechanism enables movement of larger amounts of genetic material at one time, compared with other routes of gene transfer such as natural transformation. Establishing the prevalence and functionality of this mechanism in X. fastidiosa contributes to a better understanding of HGT, adaptation, and disease emergence

Family functioning, burden and parenting stress 2 years after very preterm birth.

Science.gov (United States)

Treyvaud, Karli; Doyle, Lex W; Lee, Katherine J; Roberts, Gehan; Cheong, Jeanie L Y; Inder, Terrie E; Anderson, Peter J

2011-06-01

Examining rates of difficulties in family functioning following very preterm birth has been a relatively neglected area of research. To examine family functioning, burden and parenting stress in families with very preterm compared with term born children, and investigate influences of parental mental health problems and child neurodevelopmental disability on family outcomes in families with preterm children. Participants were 184 very preterm and 71 term children and their parents. Parents completed the Family Assessment Device, Parenting Stress Index and Impact on Family questionnaires when their children were 2 years old (corrected for prematurity). Parental mental health and social risk information were also collected. Children were assessed for neurodevelopmental disability. Families with very preterm children reported poorer family functioning (p=.03) compared with families with term born children, with less evidence for differences between families with very preterm and term born children in parenting stress and family burden. Within very preterm families, parental mental health problems were associated with higher levels of parenting stress (p=.001), and parents of children with a neurodevelopmental disability were more likely to report higher family burden (p=.04). For families with very preterm children, parental mental health symptoms and child neurodevelopmental disability may identify families at risk of greater stress and burden who may benefit from additional support. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Objective effect manifestation of pectus excavatum on load-stressed pulmonary function testing: a case report

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Chan Jason

2011-12-01

Full Text Available Abstract Introduction Pectus excavatum is the most common congenital deformity of the anterior chest wall that, under certain conditions, may pose functional problems due to cardiopulmonary compromise and exercise intolerance. Case presentation We present the case of an otherwise physically-adept 21-year-old Chinese sportsman with idiopathic pectus excavatum, whose symptoms manifested only on bearing a loaded body vest and backpack during physical exercise. Corroborative objective evidence was obtained via load-stressed pulmonary function testing, which demonstrated restrictive lung function. Conclusion This report highlights the possible detrimental synergism of thoracic load stress and pectus excavatum on cardiopulmonary function. Thoracic load-stressed pulmonary function testing provides objective evidence in support of such a synergistic relationship.

Comparing the Selected Transfer Functions and Local Optimization Methods for Neural Network Flood Runoff Forecast

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Petr Maca

2014-01-01

Full Text Available The presented paper aims to analyze the influence of the selection of transfer function and training algorithms on neural network flood runoff forecast. Nine of the most significant flood events, caused by the extreme rainfall, were selected from 10 years of measurement on small headwater catchment in the Czech Republic, and flood runoff forecast was investigated using the extensive set of multilayer perceptrons with one hidden layer of neurons. The analyzed artificial neural network models with 11 different activation functions in hidden layer were trained using 7 local optimization algorithms. The results show that the Levenberg-Marquardt algorithm was superior compared to the remaining tested local optimization methods. When comparing the 11 nonlinear transfer functions, used in hidden layer neurons, the RootSig function was superior compared to the rest of analyzed activation functions.

Minority stress and relationship functioning among young male same-sex couples: An examination of actor-partner interdependence models.

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Feinstein, Brian A; McConnell, Elizabeth; Dyar, Christina; Mustanski, Brian; Newcomb, Michael E

2018-05-01

In different-sex couples, individual and partner stress can both have a negative impact on relationship functioning (actor and partner effects). Gay and bisexual men experience unique stress (sexual minority stress), but few studies have examined the effects of this stress on relationship functioning among young male couples. The current study examined (a) actor and partner effects of general and minority stress (internalized stigma, microaggressions, victimization, and outness) on relationship functioning (relationship quality and negative relationship interactions), (b) interactions between individual and partner stress as predictors of relationship functioning, and (c) dyadic coping and relationship length as moderators of actor and partner effects. Actor-partner interdependence models were tested using data from 153 young male couples. There was strong support for actor effects. Higher general stress and internalized stigma were associated with lower relationship quality, but only for those in longer relationships. Additionally, higher general stress, internalized stigma, and microaggressions, and lower outness, were associated with more negative relationship interactions. There was limited support for partner effects. Having a partner with higher internalized stigma was associated with more negative relationship interactions, but none of the other partner effects were significant. There was no support for individual and partner stress interacting to predict relationship functioning or for dyadic coping as a stress buffer. Findings highlight the influence of one's own experiences of general and minority stress on relationship functioning, but raise questions about how partner stress influences relationship functioning among young male couples. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Measurement of the transfer function of the main SPS Quadrupoles

CERN Document Server

Dinius, A; Semanaz, P; CERN. Geneva. SPS and LEP Division

1998-01-01

During two short MD's we have measured the transfer function (amplitude and phase) of the main quadrupole string QD. By the word string we mean the global effect of power supplies, magnets and the eddy current effects of the vacuum chamber. This paper presents the measurement procedure and the results, which are needed for the design of a real-time feedback system for the betatron tunes ( Qloop).

Blunted amygdala functional connectivity during a stress task in alcohol dependent individuals: A pilot study

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Natasha E. Wade, M.S.

2017-12-01

Full Text Available Background: Scant research has been conducted on neural mechanisms underlying stress processing in individuals with alcohol dependence (AD. We examined neural substrates of stress in AD individuals compared with controls using an fMRI task previously shown to induce stress, assessing amygdala functional connectivity to medial prefrontal cortex (mPFC. Materials and methods: For this novel pilot study, 10 abstinent AD individuals and 11 controls completed a modified Trier stress task while undergoing fMRI acquisition. The amygdala was used as a seed region for whole-brain seed-based functional connectivity analysis. Results: After controlling for family-wise error (p = 0.05, there was significantly decreased left and right amygdala connectivity with frontal (specifically mPFC, temporal, parietal, and cerebellar regions. Subjective stress, but not craving, increased from pre-to post-task. Conclusions: This study demonstrated decreased connectivity between the amygdala and regions important for stress and emotional processing in long-term abstinent individuals with AD. These results suggest aberrant stress processing in individuals with AD even after lengthy periods of abstinence. Keywords: Alcohol dependence, fMRI, Stress task, Functional connectivity, Amygdala

Calculation of a steam generating tube stressed state under temperature oscillations in burnout zone

International Nuclear Information System (INIS)

Vorob'ev, V.A.; Loshchinin, V.M.; Remizov, O.V.

1982-01-01

The technique for evaluating the steam generating tube stressed state under the wall temperature oscillations in the burnout zone is described. The technique is based on analytical solutions for transfer functions connecting the amplitude of surface temperature oscillation with the amplitude and frequency of heat transfer coefficient oscillation and amplitude of thermoelastic stress oscillation with that of temperature oscillation. The results of calculations according to considered technique are compared with that of the problem numerical solution. The conclusion is made that the technique under consideration may be applied for evaluation of steam generator evaporating tube lifetime [ru

Rethinking Functional Outcome Measures: The Development of a Novel Upper Limb Token Transfer Test to Assess Basal Ganglia Dysfunction

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Susanne P. Clinch

2018-05-01

Full Text Available The basal ganglia are implicated in a wide range of motor, cognitive and behavioral activities required for normal function. This region is predominantly affected in Huntington's disease (HD, meaning that functional ability progressively worsens. However, functional outcome measures for HD, particularly those for the upper limb, are limited meaning there is an imperative for well-defined, quantitative measures. Here we describe the development and evaluation of the Moneybox test (MBT. This novel, functional upper limb assessment was developed in accordance with translational neuroscience and physiological principles for people with a broad disease manifestation, such as HD. Participants with HD (n = 64 and healthy controls (n = 21 performed the MBT, which required subjects to transfer tokens into a container in order of size (Baseline Transfer, value (Complex Transfer with and without reciting the alphabet (Dual Transfer. Disease specific measures of motor, cognition, behavior, and function were collected. HD patients were grouped into disease stage, from which, discriminative and convergent validity was assessed using Analysis of Variance and Pearson's correlation respectively. Manifest HD participants were slower than pre-manifest and control participants, and achieved significantly lower MBT total scores. Performance in the Complex Transfer and Dual Transfer tasks were significantly different between pre-manifest and stage 1 HD. All MBT performance variables significantly correlated with routinely used measures of motor, cognition, behavior, and function. The MBT provides a valid, sensitive, and affordable functional outcome measure. Unlike current assessments, MBT performance significantly distinguished the subtle differences between the earliest disease stages of HD, which are the populations typically targeted in clinical trials.

Electricity price forecasting through transfer function models

International Nuclear Information System (INIS)

Nogales, F.J.; Conejo, A.J.

2006-01-01

Forecasting electricity prices in present day competitive electricity markets is a must for both producers and consumers because both need price estimates to develop their respective market bidding strategies. This paper proposes a transfer function model to predict electricity prices based on both past electricity prices and demands, and discuss the rationale to build it. The importance of electricity demand information is assessed. Appropriate metrics to appraise prediction quality are identified and used. Realistic and extensive simulations based on data from the PJM Interconnection for year 2003 are conducted. The proposed model is compared with naive and other techniques. Journal of the Operational Research Society (2006) 57, 350-356.doi:10.1057/palgrave.jors.2601995; published online 18 May 2005. (author)

The effect of additional equilibrium stress functions on the three-node hybrid-mixed curved beam element

International Nuclear Information System (INIS)

Kim, Jin Gon; Park, Yong Kuk

2008-01-01

To develop an effective hybrid-mixed element, it is extremely critical as to how to assume the stress field. This research article demonstrates the effect of additional equilibrium stress functions to enhance the numerical performance of the locking-free three-node hybrid-mixed curved beam element, proposed in Saleeb and Chang's previous work. It is exceedingly complicated or even infeasible to determine the stress functions to satisfy fully both the equilibrium conditions and suppression of kinematic deformation modes in the three-node hybrid-mixed formulation. Accordingly, the additional stress functions to satisfy partially or fully equilibrium conditions are incorporated in this study. Several numerical examples for static and dynamic problems confirm that the newly proposed element with these additional stress functions is highly effective regardless of the slenderness ratio and curvature of arches in static and dynamic analyses

The Relationship between Stress and Social Functioning in Adults with Autism Spectrum Disorder and without Intellectual Disability

Science.gov (United States)

Bishop-Fitzpatrick, Lauren; Mazefsky, Carla A.; Minshew, Nancy J.; Eack, Shaun M.

2014-01-01

Scientific Abstract Adults with autism spectrum disorder (ASD) face substantial challenges accomplishing basic tasks associated with daily living, which are exacerbated by their broad and pervasive difficulties with social interactions. These challenges put people with ASD at increased risk for psychophysiological distress, which likely factors heavily into social functioning for adults with ASD, as suggested by a growing literature on stress in children that indicates that children with ASD have differential responses to stress than healthy children. We hypothesized that adults with ASD and without intellectual disability (n=38) would experience more stress than healthy volunteers (n=37) and that there would be an inverse relationship between stress and social functioning in individuals with ASD. Baseline, semi-structured interview data from a randomized-controlled trial of two treatments for adults with ASD were used to assess differences in stress between adults with ASD and healthy volunteers and to assess the relationship between stress response and social functioning in adults with ASD. Findings indicate that adults with ASD experience greater perceived and interviewer-observed stress than did healthy volunteers and that stress is significantly related to social functioning in adults with ASD. These findings highlight the role of stress in adult functioning and outcomes and suggest the need to develop and assess treatments designed to target stress and coping in adults with ASD. PMID:25524571

Loss of melanocortin-4 receptor function attenuates HPA responses to psychological stress

DEFF Research Database (Denmark)

Ryan, Karen K; Mul, Joram D; Clemmensen, Christoffer

2014-01-01

function. These results support the hypothesis that endogenous MC4R signaling contributes to the HPA axis response to stress. Because MC4R plays a critical role in the regulation of energy balance, the present work suggests that it may also serve as an important communication link between brain metabolic...... in hypothalamic-pituitary-adrenocortical axis (HPA) regulation. The present work investigated the role of chronic Mc4r function to modulate basal HPA axis tone and to facilitate acute HPA responses to psychological stress, using a novel rat model with Mc4r loss-of-function. In this study, adult male rats were......The melanocortin 4 receptor (MC4R), well-known for its role in the regulation of energy balance, is widely expressed in stress-regulatory brain regions, including the paraventricular nucleus of the hypothalamus (PVH) and the medial amygdala (MeA). In agreement with this, MC4R has been implicated...

Dynamic functional connectivity and individual differences in emotions during social stress.

Science.gov (United States)

Tobia, Michael J; Hayashi, Koby; Ballard, Grey; Gotlib, Ian H; Waugh, Christian E

2017-12-01

Exposure to acute stress induces multiple emotional responses, each with their own unique temporal dynamics. Dynamic functional connectivity (dFC) measures the temporal variability of network synchrony and captures individual differences in network neurodynamics. This study investigated the relationship between dFC and individual differences in emotions induced by an acute psychosocial stressor. Sixteen healthy adult women underwent fMRI scanning during a social evaluative threat (SET) task, and retrospectively completed questionnaires that assessed individual differences in subjectively experienced positive and negative emotions about stress and stress relief during the task. Group dFC was decomposed with parallel factor analysis (PARAFAC) into 10 components, each with a temporal signature, spatial network of functionally connected regions, and vector of participant loadings that captures individual differences in dFC. Participant loadings of two networks were positively correlated with stress-related emotions, indicating the existence of networks for positive and negative emotions. The emotion-related networks involved the ventromedial prefrontal cortex, cingulate cortex, anterior insula, and amygdala, among other distributed brain regions, and time signatures for these emotion-related networks were uncorrelated. These findings demonstrate that individual differences in stress-induced positive and negative emotions are each uniquely associated with large-scale brain networks, and suggest that dFC is a mechanism that generates individual differences in the emotional components of the stress response. Hum Brain Mapp 38:6185-6205, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

HEATING AND ULTRAVIOLET LIGHT ACTIVATE ANTI-STRESS GENE FUNCTIONS IN HUMANS

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Victor Fadeevitch Semenkov

2015-07-01

Full Text Available All types of cell stress are accompanied by the activation of anti-stress genes that can suppress ROS synthesis. We hypothesized that different environmental factors would affect organisms through the activation of anti-stress genes by autologous serum (AS proteins, followed by the synthesis of molecules that increase cell resistance to oxidative stress. The goal of this work was to study the influence of AS on ROS production by peripheral blood neutrophils isolated from donors in different age groups. Neutrophils were isolated from 59 donors (38-94 years old. AS was heated at 100˚C for 30 sec. or irradiated by ultraviolet light (UV at 200-280 nm and 8 W for 10 min. Neutrophils were exposed to heat shock at 42˚C for 1 min. (short-term heating stress or 43˚C for 10 min., followed by the determination of the chemiluminescence reaction induced by zymosan. AS can increase or decrease ROS production by neutrophils depending on the structure of the proteins in the serum; these structures can be changed by heating or UV treatment and the temperature of their interaction (4˚C or 37˚C. We propose that the effect of environmental factors on AS proteins can cause an adverse increase in oxidative stress levels due to the functional reduction of anti-stress genes. We found a negative correlation between the quantity of intracellular Hsp70 and levels of intracellular ROS production following 10 minutes of heat shock at 43°C. Short-term heating stress (1 minute at 42°C was followed by a prominent reduction in ROS production. This effect may be a result of the impact of the hormone adrenaline on the functions of anti-stress genes. Indeed, the same effect was observed after treatment of the neutrophils with adrenaline at concentrations of 10-4 M and 10-5 M. In contrast, dexamethasone from the other stress hormone group did not evoke the same effect at the same concentrations.

From transcriptome to biological function: environmental stress in an ectothermic vertebrate, the coral reef fish Pomacentrus moluccensis

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Ward Alister C

2007-10-01

Full Text Available Abstract Background Our understanding of the importance of transcriptional regulation for biological function is continuously improving. We still know, however, comparatively little about how environmentally induced stress affects gene expression in vertebrates, and the consistency of transcriptional stress responses to different types of environmental stress. In this study, we used a multi-stressor approach to identify components of a common stress response as well as components unique to different types of environmental stress. We exposed individuals of the coral reef fish Pomacentrus moluccensis to hypoxic, hyposmotic, cold and heat shock and measured the responses of approximately 16,000 genes in liver. We also compared winter and summer responses to heat shock to examine the capacity for such responses to vary with acclimation to different ambient temperatures. Results We identified a series of gene functions that were involved in all stress responses examined here, suggesting some common effects of stress on biological function. These common responses were achieved by the regulation of largely independent sets of genes; the responses of individual genes varied greatly across different stress types. In response to heat exposure over five days, a total of 324 gene loci were differentially expressed. Many heat-responsive genes had functions associated with protein turnover, metabolism, and the response to oxidative stress. We were also able to identify groups of co-regulated genes, the genes within which shared similar functions. Conclusion This is the first environmental genomic study to measure gene regulation in response to different environmental stressors in a natural population of a warm-adapted ectothermic vertebrate. We have shown that different types of environmental stress induce expression changes in genes with similar gene functions, but that the responses of individual genes vary between stress types. The functions of heat

Transferability of species distribution models: a functional habitat approach for two regionally threatened butterflies.

Science.gov (United States)

Vanreusel, Wouter; Maes, Dirk; Van Dyck, Hans

2007-02-01

Numerous models for predicting species distribution have been developed for conservation purposes. Most of them make use of environmental data (e.g., climate, topography, land use) at a coarse grid resolution (often kilometres). Such approaches are useful for conservation policy issues including reserve-network selection. The efficiency of predictive models for species distribution is usually tested on the area for which they were developed. Although highly interesting from the point of view of conservation efficiency, transferability of such models to independent areas is still under debate. We tested the transferability of habitat-based predictive distribution models for two regionally threatened butterflies, the green hairstreak (Callophrys rubi) and the grayling (Hipparchia semele), within and among three nature reserves in northeastern Belgium. We built predictive models based on spatially detailed maps of area-wide distribution and density of ecological resources. We used resources directly related to ecological functions (host plants, nectar sources, shelter, microclimate) rather than environmental surrogate variables. We obtained models that performed well with few resource variables. All models were transferable--although to different degrees--among the independent areas within the same broad geographical region. We argue that habitat models based on essential functional resources could transfer better in space than models that use indirect environmental variables. Because functional variables can easily be interpreted and even be directly affected by terrain managers, these models can be useful tools to guide species-adapted reserve management.

Heterodyne technique for measuring the amplitude and phase transfer functions of an optical modulator

DEFF Research Database (Denmark)

Romstad, Francis Pascal; Birkedal, Dan; Mørk, Jesper

2002-01-01

In this letter, we propose a technique based on heterodyne detection for accurately and simultaneously measuring the amplitude and phase transfer functions of an optical modulator. The technique is used to characterize an InGaAsp multiple quantum-well electroabsorption modulator. From the measure...... the measurements we derive the small-signal alpha-parameter and the time-dependent chirp for different operation conditions.......In this letter, we propose a technique based on heterodyne detection for accurately and simultaneously measuring the amplitude and phase transfer functions of an optical modulator. The technique is used to characterize an InGaAsp multiple quantum-well electroabsorption modulator. From...

Load transfer in bovine plexiform bone determined by synchrotron x-ray diffraction

International Nuclear Information System (INIS)

Akhtar, R.; Daymond, M.; Almer, J.; Mummery, P.; The Univ. of Manchester; Queen's Univ.

2008-01-01

High-energy synchrotron x-ray diffraction (XRD) has been used to quantify load transfer in bovine plexiform bone. By using both wide-angle and small-angle XRD, strains in the mineral as well as the collagen phase of bone were measured as a function of applied compressive stress. We suggest that a greater proportion of the load is borne by the more mineralized woven bone than the lamellar bone as the applied stress increases. With a further increase in stress, load is shed back to the lamellar regions until macroscopic failure occurs. The reported data fit well with reported mechanisms of microdamage accumulation in bovine plexiform bone

XML Storage for Magnetotelluric Transfer Functions: Towards a Comprehensive Online Reference Database

Science.gov (United States)

Kelbert, A.; Blum, C.

2015-12-01

Magnetotelluric Transfer Functions (MT TFs) represent most of the information about Earth electrical conductivity found in the raw electromagnetic data, providing inputs for further inversion and interpretation. To be useful for scientific interpretation, they must also contain carefully recorded metadata. Making these data available in a discoverable and citable fashion would provide the most benefit to the scientific community, but such a development requires that the metadata is not only present in the file but is also searchable. The most commonly used MT TF format to date, the historical Society of Exploration Geophysicists Electromagnetic Data Interchange Standard 1987 (EDI), no longer supports some of the needs of modern magnetotellurics, most notably accurate error bars recording. Moreover, the inherent heterogeneity of EDI's and other historic MT TF formats has mostly kept the community away from healthy data sharing practices. Recently, the MT team at Oregon State University in collaboration with IRIS Data Management Center developed a new, XML-based format for MT transfer functions, and an online system for long-term storage, discovery and sharing of MT TF data worldwide (IRIS SPUD; www.iris.edu/spud/emtf). The system provides a query page where all of the MT transfer functions collected within the USArray MT experiment and other field campaigns can be searched for and downloaded; an automatic on-the-fly conversion to the historic EDI format is also included. To facilitate conversion to the new, more comprehensive and sustainable, XML format for MT TFs, and to streamline inclusion of historic data into the online database, we developed a set of open source format conversion tools, which can be used for rotation of MT TFs as well as a general XML EDI converter (https://seiscode.iris.washington.edu/projects/emtf-fcu). Here, we report on the newly established collaboration between the USGS Geomagnetism Program and the Oregon State University to gather and

Association Between Parenting Stress and Functional Impairment Among Children Diagnosed with Neurodevelopmental Disorders.

Science.gov (United States)

Almogbel, Yasser S; Goyal, Rohit; Sansgiry, Sujit S

2017-05-01

The objective of this study was to examine the association between parenting stress and functional impairment among children with Neurodevelopmental Disorder (NDD). A sample of 150 parents of children diagnosed with NDD were recruited from schools that offer special education services. Parents completed a self-administered survey containing the parenting stress index-short form (PSI-SF) scale and the Columbia Impairment Scale. The multiple logistic regression conducted to compare those with clinically significant PSI-SF scores indicated that the risk of parents with clinically significant scores of parenting stress increased 5.5 times with functionally impaired children with NDD. Further the risk of stress increased 4.6 times when these parents reported having their own disorder/disease. The risk of stress was reduced by 57% for those who had higher than a college level education compared to those with a college level education or below. These findings might help health care providers to initiate early intervention strategies such as peer support and education that can prevent parenting stress and reduce the risk of potential incidence of depression.

On Taylor-Series Approximations of Residual Stress

Science.gov (United States)

Pruett, C. David

1999-01-01

Although subgrid-scale models of similarity type are insufficiently dissipative for practical applications to large-eddy simulation, in recently published a priori analyses, they perform remarkably well in the sense of correlating highly against exact residual stresses. Here, Taylor-series expansions of residual stress are exploited to explain the observed behavior and "success" of similarity models. Until very recently, little attention has been given to issues related to the convergence of such expansions. Here, we re-express the convergence criterion of Vasilyev [J. Comput. Phys., 146 (1998)] in terms of the transfer function and the wavenumber cutoff of the grid filter.

Immediate and long-term effects of meditation on acute stress reactivity, cognitive functions, and intelligence.

Science.gov (United States)

Singh, Yogesh; Sharma, Ratna; Talwar, Anjana

2012-01-01

With the current globalization of the world's economy and demands for enhanced performance, stress is present universally. Life's stressful events and daily stresses cause both deleterious and cumulative effects on the human body. The practice of meditation might offer a way to relieve that stress. The research team intended to study the effects of meditation on stress-induced changes in physiological parameters, cognitive functions, intelligence, and emotional quotients. The research team conducted the study in two phases, with a month between them. Each participant served as his own control, and the first phase served as the control for the second phase. In phase 1, the research team studied the effects of a stressor (10 minutes playing a computer game) on participants' stress levels. In phase 2, the research team examined the effects of meditation on stress levels. The research team conducted the study in a lab setting at the All India Institute of Medical Sciences (AIIMS), New Delhi, India. The participants were 34 healthy, male volunteers who were students. To study the effects of long-term meditation on stress levels, intelligence, emotional quotients, and cognitive functions participants meditated daily for 1 month, between phases 1 and 2. To study the immediate effects of meditation on stress levels, participants meditated for 15 minutes after playing a computer game to induce stress. The research team measured galvanic skin response (GSR), heart rate (HR), and salivary cortisol and administered tests for the intelligence and emotional quotients (IQ and EQ), acute and perceived stress (AS and PS), and cognitive functions (ie, the Sternberg memory test [short-term memory] and the Stroop test [cognitive flexibility]). Using a pre-post study design, the team performed this testing (1) prior to the start of the study (baseline); (2) in phase 1, after induced stress; (3) in part 1 of phase 2, after 1 month of daily meditation, and (4) in part 2 of phase 2, after

Functional brain activation associated with working memory training and transfer.

Science.gov (United States)

Clark, Cameron M; Lawlor-Savage, Linette; Goghari, Vina M

2017-09-15

While behavioural trials of working memory (WM) training have received much attention in recent years, a lesser explored parallel approach is functional neuroimaging. A small literature has suggested a complex time course for functional activation pattern changes following WM training (i.e. not simply increasing or decreasing due to training); however, no study to date has examined such neuroplastic effects in both the training task (dual n-back) and the fluid intelligence transfer task to which the training is purported to transfer (Raven's Matrices). This study investigated neural correlates of WM training in healthy young adults randomized to six weeks of WM training, or an active control condition (processing speed training) with a pre- and post-training fMRI design. Results indicated significant reductions in activation for the WM trained group in key WM-task related areas for trained WM tasks after training compared to the processing speed active control group. The same pattern of training related decreases in activation for the WM trained group was not observed for the transfer task, which is consistent with null results for all cognitive outcomes of the present trial. The observed pattern of results suggests that repetitive practice with a complex task does indeed lead to neuroplastic processes that very likely represent the reduced demand for attentional control while sub-components of the task become more routinized with practice. We suggest that future research investigate neural correlates of WM training in populations for which WM itself is impaired and/or behavioural trials of WM training have returned more promising results. Copyright © 2017 Elsevier B.V. All rights reserved.

Stressful Life Events in Children With Functional Defecation Disorders

NARCIS (Netherlands)

Philips, Elise M.; Peeters, Babette; Teeuw, Arianne H.; Leenders, Arnold G. E.; Boluyt, Nicole; Brilleslijper-Kater, Sonja N.; Benninga, Marc A.

2015-01-01

The aim of the study was to determine the prevalence of stressful life events including (sexual) abuse in children with functional defecation disorders by performing a systematic review. We searched MEDLINE, EMBASE, and PsycINFO for cohort, case-control and cross-sectional studies investigating the

Induction, by thymidylate stress, of genetic recombination as evidenced by deletion of a transferred genetic marker in mouse FM3A cells

International Nuclear Information System (INIS)

Ayusawa, D.; Koyama, H.; Shimizu, K.; Kaneda, S.; Takeishi, K.; Seno, T.

1986-01-01

Studies were made on the genetic consequences of methotrexate-directed thymidylate stress, focusing attention on a human thymidylate synthase gene that was introduced as a heterologous genetic marker into mouse thymidylate synthase-negative mutant cells. Thymidylate stress induced thymidylate synthase-negative segregants with concomitant loss of human thymidylate synthase activity with frequencies 1 to 2 orders of magnitude higher than the uninduced spontaneous level in some but not all transformant lines. Induction of the segregants was suppressed almost completely by cycloheximide and partially by caffeine. Thymidylate stress did not, however, induce mutations, as determined by measuring resistance to ouabain or 6-thioguanine. Thymidylate synthase-negative segregants were also induced by other means such as bromodeoxyuridine treatment and X-ray irradiation. In each of the synthase-negative segregants induced by thymidylate stress, a DNA segment including almost the whole coding region of the transferred human thymidylate synthase gene was deleted in a very specific manner, as shown by Southern blot analysis with a human Alu sequence and a human thymidylate synthase cDNA as probes. In the segregants that emerged spontaneously at low frequency, the entire transferred genetic marker was lost. In the segregants induced by X-ray irradiation, structural alterations of the genetic marker were random. These results show that thymidylate stress is a physiological factor that provokes the instability of this exogenously incorporated DNA in some specific manner and produces nonrandom genetic recombination in mammalian cells

Complementary Strategies for Directed C(sp3 )-H Functionalization: A Comparison of Transition-Metal-Catalyzed Activation, Hydrogen Atom Transfer, and Carbene/Nitrene Transfer.

Science.gov (United States)

Chu, John C K; Rovis, Tomislav

2018-01-02

The functionalization of C(sp 3 )-H bonds streamlines chemical synthesis by allowing the use of simple molecules and providing novel synthetic disconnections. Intensive recent efforts in the development of new reactions based on C-H functionalization have led to its wider adoption across a range of research areas. This Review discusses the strengths and weaknesses of three main approaches: transition-metal-catalyzed C-H activation, 1,n-hydrogen atom transfer, and transition-metal-catalyzed carbene/nitrene transfer, for the directed functionalization of unactivated C(sp 3 )-H bonds. For each strategy, the scope, the reactivity of different C-H bonds, the position of the reacting C-H bonds relative to the directing group, and stereochemical outcomes are illustrated with examples in the literature. The aim of this Review is to provide guidance for the use of C-H functionalization reactions and inspire future research in this area. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functionalizing Arrays of Transferred Monolayer Graphene on Insulating Surfaces by Bipolar Electrochemistry

DEFF Research Database (Denmark)

Koefoed, Line; Pedersen, Emil Bjerglund; Thyssen, Lena

2016-01-01

Development of versatile methods for graphene functionalization is necessary before use in applications such as composites or as catalyst support. In this study, bipolar electrochemistry is used as a wireless functionalization method to graft 4-bromobenzenediazonium on large (10 × 10 mm2) monolayer...... graphene sheets supported on SiO2. Using this technique, transferred graphene can be electrochemically functionalized without the need of a metal support or the deposition of physical contacts. X-ray photoelectron spectroscopy and Raman spectroscopy are used to map the chemical changes and modifications...

Functional transferred DNA within extracellular vesicles

Energy Technology Data Exchange (ETDEWEB)

Cai, Jin [Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042 (China); Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, Jiangsu Province (China); Wu, Gengze [Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042 (China); Jose, Pedro A. [Division of Nephrology, Department of Medicine and Physiology, University of Maryland, School of Medicine, Baltimore, MD 21201 (United States); Zeng, Chunyu, E-mail: Chunyuzeng01@163.com [Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing 400042 (China)

2016-11-15

Extracellular vesicles (EVs) are small membrane vesicles including exosomes and shedding vesicles that mediated a cell-to-cell communication. EVs are released from almost all cell types under both physiological and pathological conditions and incorporate nuclear and cytoplasmic molecules for intercellular delivery. Besides protein, mRNA, and microRNA of these molecules, as recent studies show, specific DNA are prominently packaged into EVs. It appears likely that some of exosomes or shedding vesicles, bearing nuclear molecules are released upon bubble-like blebs. Specific interaction of EVs with susceptible recipients performs the uptake of EVs into the target cells, discharging their cargo including nuclear and cytoplasmic macromolecules into the cytosol. These findings expand the nucleic acid content of EVs to include increased levels of specific DNA. Thus, EVs contain a repertoire of genetic information available for horizontal gene transfer and potential use as blood biomarkers for cancer and atherosclerosis. In this review, the focus is on the characteristics, biological functions, and roles in diseases of DNA within EVs. - Highlights: • This review is focused on the DNA within EVs including its characteristics, biological functions, and roles in diseases. • It is clear that DNA within EVs might have important physiological and pathological roles in various diseases. • Knowledge in this area may provides us alternative methods for disease diagnosis or therapy in the future.

Functional transferred DNA within extracellular vesicles

International Nuclear Information System (INIS)

Cai, Jin; Wu, Gengze; Jose, Pedro A.; Zeng, Chunyu

2016-01-01

Extracellular vesicles (EVs) are small membrane vesicles including exosomes and shedding vesicles that mediated a cell-to-cell communication. EVs are released from almost all cell types under both physiological and pathological conditions and incorporate nuclear and cytoplasmic molecules for intercellular delivery. Besides protein, mRNA, and microRNA of these molecules, as recent studies show, specific DNA are prominently packaged into EVs. It appears likely that some of exosomes or shedding vesicles, bearing nuclear molecules are released upon bubble-like blebs. Specific interaction of EVs with susceptible recipients performs the uptake of EVs into the target cells, discharging their cargo including nuclear and cytoplasmic macromolecules into the cytosol. These findings expand the nucleic acid content of EVs to include increased levels of specific DNA. Thus, EVs contain a repertoire of genetic information available for horizontal gene transfer and potential use as blood biomarkers for cancer and atherosclerosis. In this review, the focus is on the characteristics, biological functions, and roles in diseases of DNA within EVs. - Highlights: • This review is focused on the DNA within EVs including its characteristics, biological functions, and roles in diseases. • It is clear that DNA within EVs might have important physiological and pathological roles in various diseases. • Knowledge in this area may provides us alternative methods for disease diagnosis or therapy in the future.

Resistance of functional Lactobacillus plantarum strains against food stress conditions.

Science.gov (United States)

Ferrando, Verónica; Quiberoni, Andrea; Reinhemer, Jorge; Suárez, Viviana

2015-06-01

The survival of three Lactobacillus plantarum strains (Lp 790, Lp 813 and Lp 998) with functional properties was studied taking into account their resistance to thermal, osmotic and oxidative stress factors. Stress treatments applied were: 52 °C-15 min (Phosphate Buffer pH 7, thermal shock), H2O2 0.1% (p/v) - 30 min (oxidative shock) and NaCl aqueous solution at 17, 25 and 30% (p/v) (room temperature - 1 h, osmotic shock). The osmotic stress was also evaluated on cell growth in MRS broth added of 2, 4, 6, 8 and 10% (p/v) of NaCl, during 20 h at 30 °C. The cell thermal adaptation was performed in MRS broth, selecting 45 °C for 30 min as final conditions for all strains. Two strains (Lp 813 and Lp 998) showed, in general, similar behaviour against the three stress factors, being clearly more resistant than Lp 790. An evident difference in growth kinetics in presence of NaCl was observed between Lp 998 and Lp 813, Lp998 showing a higher optical density (OD570nm) than Lp 813 at the end of the assay. Selected thermal adaptation improved by 2 log orders the thermal resistance of both strains, but cell growth in presence of NaCl was enhanced only in Lp 813. Oxidative resistance was not affected with this thermal pre-treatment. These results demonstrate the relevance of cell technological resistance when selecting presumptive "probiotic" cultures, since different stress factors might considerably affect viability or/and performance of the strains. The incidence of stress conditions on functional properties of the strains used in this work are currently under research in our group. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterizing 3D sensors using the 3D modulation transfer function

Science.gov (United States)

Kellner, Timo; Breitbarth, Andreas; Zhang, Chen; Notni, Gunther

2018-03-01

The fields of optical 3D measurement system applications are continuously expanding and becoming more and more diverse. To evaluate appropriate systems for various measurement tasks, comparable parameters are necessary, whereas the 3D modulation transfer function (3D-MTF) has been established as a further criterion. Its aim is the determination of the system response between the measurement of a straight, sharp-edged cube and its opposite ideal calculated one. Within the scope of this work simulations and practical investigations regarding the 3D-MTF’s influences and its main issues are specifically investigated. Therefore, different determined edge radii representing the high-frequency spectra lead to various decreasing 3D-MTF characteristics. Furthermore, rising sampling frequencies improve its maximum transfer value to a saturation point in dependence of the radius. To approve these results of previous simulations, three fringe projection scanners were selected to determine the diversity. As the best 3D-MTF characteristic, a saturated transfer value of H_3D( f_N, 3D) = 0.79 has been identified at a sufficient sampling frequency, which is reached at four times the Nyquist limit. This high 3D resolution can mainly be achieved due to an improved camera projector interaction. Additionally, too small sampling ratios lead to uncertainties in the edge function determination, while higher ratios do not show major improvements. In conclusion, the 3D-MTF algorithm has thus been practically verified and its repeatability as well as its robustness have been confirmed.

Glucocorticoid Mechanisms of Functional Connectivity Changes in Stress-Related Neuropsychiatric Disorders.

Science.gov (United States)

Hall, Baila S; Moda, Rachel N; Liston, Conor

2015-01-01

Stress-especially chronic, uncontrollable stress-is an important risk factor for many neuropsychiatric disorders. The underlying mechanisms are complex and multifactorial, but they involve correlated changes in structural and functional measures of neuronal connectivity within cortical microcircuits and across neuroanatomically distributed brain networks. Here, we review evidence from animal models and human neuroimaging studies implicating stress-associated changes in functional connectivity in the pathogenesis of PTSD, depression, and other neuropsychiatric conditions. Changes in fMRI measures of corticocortical connectivity across distributed networks may be caused by specific structural alterations that have been observed in the prefrontal cortex, hippocampus, and other vulnerable brain regions. These effects are mediated in part by glucocorticoids, which are released from the adrenal gland in response to a stressor and also oscillate in synchrony with diurnal rhythms. Recent work indicates that circadian glucocorticoid oscillations act to balance synapse formation and pruning after learning and during development, and chronic stress disrupts this balance. We conclude by considering how disrupted glucocorticoid oscillations may contribute to the pathophysiology of depression and PTSD in vulnerable individuals, and how circadian rhythm disturbances may affect non-psychiatric populations, including frequent travelers, shift workers, and patients undergoing treatment for autoimmune disorders.

The modified couple stress functionally graded Timoshenko beam formulation

International Nuclear Information System (INIS)

Asghari, M.; Rahaeifard, M.; Kahrobaiyan, M.H.; Ahmadian, M.T.

2011-01-01

In this paper, a size-dependent formulation is presented for Timoshenko beams made of a functionally graded material (FGM). The formulation is developed on the basis of the modified couple stress theory. The modified couple stress theory is a non-classic continuum theory capable to capture the small-scale size effects in the mechanical behavior of structures. The beam properties are assumed to vary through the thickness of the beam. The governing differential equations of motion are derived for the proposed modified couple-stress FG Timoshenko beam. The generally valid closed-form analytic expressions are obtained for the static response parameters. As case studies, the static and free vibration of the new model are respectively investigated for FG cantilever and FG simply supported beams in which properties are varying according to a power law. The results indicate that modeling beams on the basis of the couple stress theory causes more stiffness than modeling based on the classical continuum theory, such that for beams with small thickness, a significant difference between the results of these two theories is observed.

Attentional avoidance of fearful facial expressions following early life stress is associated with impaired social functioning.

Science.gov (United States)

Humphreys, Kathryn L; Kircanski, Katharina; Colich, Natalie L; Gotlib, Ian H

2016-10-01

Early life stress is associated with poorer social functioning. Attentional biases in response to threat-related cues, linked to both early experience and psychopathology, may explain this association. To date, however, no study has examined attentional biases to fearful facial expressions as a function of early life stress or examined these biases as a potential mediator of the relation between early life stress and social problems. In a sample of 154 children (ages 9-13 years) we examined the associations among interpersonal early life stressors (i.e., birth through age 6 years), attentional biases to emotional facial expressions using a dot-probe task, and social functioning on the Child Behavior Checklist. High levels of early life stress were associated with both greater levels of social problems and an attentional bias away from fearful facial expressions, even after accounting for stressors occurring in later childhood. No biases were found for happy or sad facial expressions as a function of early life stress. Finally, attentional biases to fearful faces mediated the association between early life stress and social problems. Attentional avoidance of fearful facial expressions, evidenced by a bias away from these stimuli, may be a developmental response to early adversity and link the experience of early life stress to poorer social functioning. © 2016 Association for Child and Adolescent Mental Health.

Chronic stress and pituitary-adrenal function in female pigs

NARCIS (Netherlands)

Janssens, C.J.J.G.

1994-01-01

Introduction

The main purpose of the studies described in this thesis was to gain more insight in the regulation of the hypothalamic-pituitary-adrenocorticaI (HPA) system and the mechanisms underlying adaptation to chronic stress in female pigs. The function of the HPA axis, which

Use of a novel transfer function to reduce repolarization interval hysteresis

Czech Academy of Sciences Publication Activity Database

Halámek, Josef; Jurák, Pavel; Bunch, T.J.; Lipoldová, J.; Novák, M.; Vondra, Vlastimil; Leinveber, Pavel; Plachý, M.; Kára, T.; Villa, M.; Fráňa, P.; Souček, M.; Somers, V. K.; Asirvatham, S.J.

2010-01-01

Roč. 29, č. 1 (2010), s. 23-32 ISSN 1383-875X R&D Projects: GA ČR GA102/08/1129 Institutional research plan: CEZ:AV0Z20650511 Keywords : QT hysteresis * QT/RR coupling * Transfer function * Long QT syndrome Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 1.228, year: 2010

Experimental Waterflow Determination of the Dynamic Hydraulic Transfer Function for the J-2X Oxidizer Turbopump. Part Two; Results and Interpretation

Science.gov (United States)

Zoladz, Tom; Patel, Sandeep; Lee, Erik; Karon, Dave

2011-01-01

Experimental results describing the hydraulic dynamic pump transfer matrix (Yp) for a cavitating J-2X oxidizer turbopump inducer+impeller tested in subscale waterflow are presented. The transfer function is required for integrated vehicle pogo stability analysis as well as optimization of local inducer pumping stability. Dynamic transfer functions across widely varying pump hydrodynamic inlet conditions are extracted from measured data in conjunction with 1D-model based corrections. Derived Dynamic transfer functions are initially interpreted relative to traditional Pogo pump equations. Water-to-liquid oxygen scaling of measured cavitation characteristics are discussed. Comparison of key dynamic transfer matrix terms derived from waterflow testing are made with those implemented in preliminary Ares Upper Stage Pogo stability modeling. Alternate cavitating pump hydraulic dynamic equations are suggested which better reflect frequency dependencies of measured transfer matrices.

A Clustering-Based Automatic Transfer Function Design for Volume Visualization

Directory of Open Access Journals (Sweden)

Tianjin Zhang

2016-01-01

Full Text Available The two-dimensional transfer functions (TFs designed based on intensity-gradient magnitude (IGM histogram are effective tools for the visualization and exploration of 3D volume data. However, traditional design methods usually depend on multiple times of trial-and-error. We propose a novel method for the automatic generation of transfer functions by performing the affinity propagation (AP clustering algorithm on the IGM histogram. Compared with previous clustering algorithms that were employed in volume visualization, the AP clustering algorithm has much faster convergence speed and can achieve more accurate clustering results. In order to obtain meaningful clustering results, we introduce two similarity measurements: IGM similarity and spatial similarity. These two similarity measurements can effectively bring the voxels of the same tissue together and differentiate the voxels of different tissues so that the generated TFs can assign different optical properties to different tissues. Before performing the clustering algorithm on the IGM histogram, we propose to remove noisy voxels based on the spatial information of voxels. Our method does not require users to input the number of clusters, and the classification and visualization process is automatic and efficient. Experiments on various datasets demonstrate the effectiveness of the proposed method.

Stressful life events predict delayed functional recovery following treatment for mania in bipolar disorder.

Science.gov (United States)

Yan-Meier, Leslie; Eberhart, Nicole K; Hammen, Constance L; Gitlin, Michael; Sokolski, Kenneth; Altshuler, Lori

2011-04-30

Identifying predictors of functional recovery in bipolar disorder is critical to treatment efforts to help patients re-establish premorbid levels of role adjustment following an acute manic episode. The current study examined the role of stressful life events as potential obstacles to recovery of functioning in various roles. 65 patients with bipolar I disorder participated in a longitudinal study of functional recovery following clinical recovery from a manic episode. Stressful life events were assessed as predictors of concurrent vs. delayed recovery of role functioning in 4 domains (friends, family, home duties, work/school). Despite clinical recovery, a subset of patients experienced delayed functional recovery in various role domains. Moreover, delayed functional recovery was significantly associated with presence of one or more stressors in the prior 3 months, even after controlling for mood symptoms. Presence of a stressor predicted longer time to functional recovery in life domains, up to 112 days in work/school. Interventions that provide monitoring, support, and problem-solving may be needed to help prevent or mitigate the effects of stress on functional recovery. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Effect of the Periodontal Ligament of the Bilateral Support Teeth on the Stress Analysis of Dental Implant

Directory of Open Access Journals (Sweden)

Xie Yanhua

2017-01-01

Full Text Available The aim of this work is to analyze the function of natural teeth’s periodontal ligament and the effects of periodontal ligament on implants by the finite element method (FEM, when static functional loads occur. The finite element analysis models are established, which consist of fragment of mandible, natural teeth, periodontal ligament, and implant. Finite element software Abaqus is used to analyze the stress transfer in models with or without periodontal ligament, and mandibular first molar is implant. The implant obtained the maximum stress value of 87.71MPa when periodontal ligament of natural tooth is absent, but the maximum value reduces to 38.43 MPa with the action of periodontal ligament. It illustrates that periodontal ligament has significant effects on stress transfer. When the finite element model of single natural tooth or dentition with implant is generated, periodontal ligament should be taken into account.

Measurement of the amplitude and phase transfer functions of an optical modulator using a heterodyne technique

DEFF Research Database (Denmark)

Romstad, Francis Pascal; Birkedal, Dan; Mørk, Jesper

2001-01-01

We present a new technique that measures the full amplitude and phase transfer curves of the modulator as a function of the applied bias, from which the small signal α-parameter can be calculated. The technique measures the amplitude and phase transfer functions simultaneously and directly......, compared to techniques where a time-consuming data analysis is necessary to calculate the a-parameter and an additional measurement is necessary to estimate the phase. Additionally, the chirp profile for all operation points can be calculated....

The Impact of Midurethral Sling Surgery on Sexual Activity and Function in Women With Stress Urinary Incontinence

NARCIS (Netherlands)

Mengerink, Bianca B.; van Leijsen, Sanne A. L.; Vierhout, Mark E.; IntHout, Joanna; Mol, Ben W. J.; Milani, Alfredo L.; Roovers, Jan-Paul W. R.; van Eijndhoven, Hugo W. F.; van der Vaart, Carl H.; van Gestel, Iris; Hartog, Francis E.; Heesakkers, John F. A.; Kluivers, Kirsten B.

2016-01-01

Introduction: Stress urinary incontinence has a negative impact on sexual function. Aim: To assess the effect of midurethral sling surgery on sexual activity and function in women with stress urinary incontinence. Methods: This is a secondary analysis of the Value of Urodynamics Prior to Stress

first principles derivation of a stress function for axially symmetric

African Journals Online (AJOL)

HOD

governing partial differential equations of linear isotropic elasticity were reduced to the solution of the biharmonic ... The stress function was then applied to solve the axially symmetric ..... [1] Borg S.K.: Fundamentals of Engineering Elasticity,.

Traumatic stress and psychological functioning in a South African adolescent community sample

OpenAIRE

Swain, Karl D.; Pillay, Basil J.; Kliewer, Wendy

2017-01-01

Background: Traumatic stress may arise from various incidents often leading to posttraumatic stress disorder (PTSD). The lifetime prevalence of PTSD is estimated at 1% – 2% in Western Europe, 6% – 9% in North America and at just over 10% in countries exposed to long-term violence. In South Africa, the lifetime prevalence for PTSD in the general population is estimated at 2.3%. Aim: To examine the prevalence of posttraumatic stress symptomatology and related psychological functioning in a ...

Interactions between Temperament, Stress, and Immune Function in Cattle

Directory of Open Access Journals (Sweden)

N. C. Burdick

2011-01-01

Full Text Available The detrimental effects caused by stressors encountered by animals during routine handling can pose economic problems for the livestock industry due to increased costs ultimately borne by the producer and the consumer. Stress adversely affects key physiological processes of the reproductive and immune systems. In recent years stress responsiveness has been associated with cattle behavior, specifically temperament. Cattle with more excitable temperaments, as measured by chute score, pen score, and exit velocity (flight speed, exhibit greater basal concentrations of glucocorticoids and catecholamines. Similar to stressed cattle, more temperamental cattle (i.e., cattle exhibiting greater exit velocity or pen and chute scores have poorer growth performance, carcass characteristics, and immune responses. Thus, understanding the interrelationship of stress and temperament can help in the development of selection and management practices that reduce the negative influence of temperament on growth and productivity of cattle. This paper discusses the relationship between stress and temperament and the developing evidence of an effect of temperament on immune function of cattle that have been handled or restrained. Specifically, the paper discusses different methodologies used to measure temperament, including chute score, pen score, and exit velocity, and discusses the reaction of cattle to different stressors including handling and restraint.

Influence of wall couple stress in MHD flow of a micropolar fluid in a porous medium with energy and concentration transfer

Directory of Open Access Journals (Sweden)

Asma Khalid

2018-06-01

Full Text Available The intention here is to investigate the effects of wall couple stress with energy and concentration transfer in magnetohydrodynamic (MHD flow of a micropolar fluid embedded in a porous medium. The mathematical model contains the set of linear conservation forms of partial differential equations. Laplace transforms and convolution technique are used for computation of exact solutions of velocity, microrotations, temperature and concentration equations. Numerical values of skin friction, couple wall stress, Nusselt and Sherwood numbers are also computed. Characteristics for the significant variables on the physical quantities are graphically discussed. Comparison with previously published work in limiting sense shows an excellent agreement. Keywords: Micropolor fluid, Microrotation, MHD, Porosity, Wall couple stress, Exact solutions

A real-time transfer function analyser program for PFR

International Nuclear Information System (INIS)

McWilliam, D.

1980-03-01

A transfer function analyser software package has been produced which is believed to constitute a significant advance over others reported in the literature. The main advantages of the system are its operating speed, especially at low frequencies, which is due to its use of part-cycle integration and its high degree of interactive operator control. The driving sine wave, the return signals and the computed vector diagrams are displayed on TV type visual display units. Data output is by means of an incremental graph plotter or an IBM typewriter. (author)

Audibility of spectral differences in head-related transfer functions

DEFF Research Database (Denmark)

Hoffmann, Pablo F.F.; Møller, Henrik

2006-01-01

The spatial resolution at which head-related transfer functions (HRTFs) are available is an important aspect in the implementation of three-dimensional sound. Specifically, synthesis of moving sound requires that HRTFs are sufficiently close so the simulated sound is perceived as moving smoothly....... How close they must be, depends directly on how much the characteristics of neighboring HRTFs differ, and, most important, when these differences become audible. Differences between HRTFs exist in the interaural delay (ITD) and in the spectral characteristics, i.e. the magnitude spectrum of the HRTFs...

Detecting regional lung properties using audio transfer functions of the respiratory system.

Science.gov (United States)

Mulligan, K; Adler, A; Goubran, R

2009-01-01

In this study, a novel instrument has been developed for measuring changes in the distribution of lung fluid the respiratory system. The instrument consists of a speaker that inputs a 0-4kHz White Gaussian Noise (WGN) signal into a patient's mouth and an array of 4 electronic stethoscopes, linked via a fully adjustable harness, used to recover signals on the chest surface. The software system for processing the data utilizes the principles of adaptive filtering in order to obtain a transfer function that represents the input-output relationship for the signal as the volume of fluid in the lungs is varied. A chest phantom model was constructed to simulate the behavior of fluid related diseases within the lungs through the injection of varying volumes of water. Tests from the phantom model were compared to healthy subjects. Results show the instrument can obtain similar transfer functions and sound propagation delays between both human and phantom chests.

Comparison of Regression Analysis and Transfer Function in Estimating the Parameters of Central Pulse Waves from Brachial Pulse Wave.

Science.gov (United States)

Chai, Rui; Xu, Li-Sheng; Yao, Yang; Hao, Li-Ling; Qi, Lin

2017-01-01

This study analyzed ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO), and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. Invasively measured parameters were compared with parameters measured from brachial pulse waves by regression model and transfer function model. Accuracy of parameters estimated by regression and transfer function model, was compared too. Findings showed that k value, central pulse wave and brachial pulse wave parameters invasively measured, correlated positively. Regression model parameters including A_slope, DBP, SEVR, and transfer function model parameters had good consistency with parameters invasively measured. They had same effect of consistency. SBP, PP, SV, and CO could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

Stress-responsive expression patterns and functional characterization of cold shock domain proteins in cabbage (Brassica rapa) under abiotic stress conditions.

Science.gov (United States)

Choi, Min Ji; Park, Ye Rin; Park, Su Jung; Kang, Hunseung

2015-11-01

Although the functional roles of cold shock domain proteins (CSDPs) have been demonstrated during the growth, development, and stress adaptation of Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), and wheat (Triticum aestivum), the functions of CSDPs in other plants species, including cabbage (Brassica rapa), are largely unknown. To gain insight into the roles of CSDPs in cabbage under stress conditions, the genes encoding CSDPs in cabbage were isolated, and the functional roles of CSDPs in response to environmental stresses were analyzed. Real-time RT-PCR analysis revealed that the levels of BrCSDP transcripts increased during cold, salt, or drought stress, as well as upon ABA treatment. Among the five BrCSDP genes found in the cabbage genome, one CSDP (BRU12051), named BrCSDP3, was unique in that it is localized to the chloroplast as well as to the nucleus. Ectopic expression of BrCSDP3 in Arabidopsis resulted in accelerated seed germination and better seedling growth compared to the wild-type plants under high salt or dehydration stress conditions, and in response to ABA treatment. BrCSDP3 did not affect the splicing of intron-containing genes and processing of rRNAs in the chloroplast. BrCSDP3 had the ability to complement RNA chaperone-deficient Escherichia coli mutant cells under low temperatures as well as DNA- and RNA-melting abilities, suggesting that it possesses RNA chaperone activity. Taken together, these results suggest that BrCSDP3, harboring RNA chaperone activity, plays a role as a positive regulator in seed germination and seedling growth under stress conditions. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Complexity in modeling of residual stresses and strains during polymerization of bone cement: effects of conversion, constraint, heat transfer, and viscoelastic property changes.

Science.gov (United States)

Gilbert, Jeremy L

2006-12-15

Aseptic loosening of cemented joint prostheses remains a significant concern in orthopedic biomaterials. One possible contributor to cement loosening is the development of porosity, residual stresses, and local fracture of the cement that may arise from the in-situ polymerization of the cement. In-situ polymerization of acrylic bone cement is a complex set of interacting processes that involve polymerization reactions, heat generation and transfer, full or partial mechanical constraint, evolution of conversion- and temperature-dependent viscoelastic material properties, and thermal and conversion-driven changes in the density of the cement. Interactions between heat transfer and polymerization can lead to polymerization fronts moving through the material. Density changes during polymerization can, in the presence of mechanical constraint, lead to the development of locally high residual strain energy and residual stresses. This study models the interactions during bone cement polymerization and determines how residual stresses develop in cement and incorporates temperature and conversion-dependent viscoelastic behavior. The results show that the presence of polymerization fronts in bone cement result in locally high residual strain energies. A novel heredity integral approach is presented to track residual stresses incorporating conversion and temperature dependent material property changes. Finally, the relative contribution of thermal- and conversion-dependent strains to residual stresses is evaluated and it is found that the conversion-based strains are the major contributor to the overall behavior. This framework provides the basis for understanding the complex development of residual stresses and can be used as the basis for developing more complex models of cement behavior.

Large work function difference driven electron transfer from electrides to single-walled carbon nanotubes

KAUST Repository

Menamparambath, Mini Mol

2014-06-23

A difference in work function plays a key role in charge transfer between two materials. Inorganic electrides provide a unique opportunity for electron transfer since interstitial anionic electrons result in a very low work function of 2.4-2.6 eV. Here we investigated charge transfer between two different types of electrides, [Ca2N]+·e- and [Ca 24Al28O64]4+·4e-, and single-walled carbon nanotubes (SWNTs) with a work function of 4.73-5.05 eV. [Ca2N]+·e- with open 2-dimensional electron layers was more effective in donating electrons to SWNTs than closed cage structured [Ca24Al28O64] 4+·4e- due to the higher electron concentration (1.3 × 1022 cm-3) and mobility (∼200 cm 2 V-1 s-1 at RT). A non-covalent conjugation enhanced near-infrared fluorescence of SWNTs as high as 52%. The field emission current density of electride-SWNT-silver paste dramatically increased by a factor of 46000 (14.8 mA cm-2) at 2 V μm-1 (3.5 wt% [Ca2N]+·e-) with a turn-on voltage of 0.85 V μm-1. This journal is © the Partner Organisations 2014.

Effect of Stress Urinary Incontinence on the Sexual Function of Couples and the Quality of Life of Patients.

Science.gov (United States)

Lim, Renly; Liong, Men Long; Leong, Wing Seng; Khan, Nurzalina Abdul Karim; Yuen, Kah Hay

2016-07-01

Studies of the effects of stress urinary incontinence on the sexual function of couples are scarce. We prospectively evaluated couple sexual function and the relationship between sexual function and quality of life. We also compared quality of life in females with vs without stress urinary incontinence. Sexually active females at least 21 years old with or without stress urinary incontinence and their partners were recruited for study. To assess sexual function the couples completed GRISS (Golombok Rust Inventory of Sexual Satisfaction) and a 1-item question on overall sexual experience, "Over the past 4 weeks, how satisfied have you been with your overall sexual life?" Additionally, females completed ICIQ-LUTSqol (International Consultation on Incontinence Questionnaire-Lower Urinary Tract Symptoms Quality of Life) to assess quality of life. For sexual function assessment 66 of 134 couples with (49.3%) and 95 of 176 without (54.0%) stress urinary incontinence were recruited. Females with stress urinary incontinence had lower overall sexual function, lower frequency of sexual intercourse, less satisfaction (each p stress urinary incontinence had more problems with erectile dysfunction (p = 0.027), less satisfaction (p = 0.006) and lower frequency of sexual intercourse (p = 0.001) but no difference in overall GRISS score (p = 0.093). Couples with stress urinary incontinence had poorer overall sexual experience (p stress urinary incontinence had poorer quality of life than those without stress urinary incontinence (120 of 134, response rate 89.6% vs 145 of 176, response rate 82.4%, p life did not significantly correlate (r = 0.001, p = 0.997). Stress urinary incontinence in females is negatively associated not only with female quality of life and sexual function but also with partner sexual function. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Effect of stress hyperglycemia and intensive rehabilitation therapy in non-diabetic hemorrhagic stroke: Korean Stroke Cohort for Functioning and Rehabilitation.

Science.gov (United States)

Yoon, J A; Kim, D Y; Sohn, M K; Lee, J; Lee, S-G; Lee, Y-S; Han, E Y; Joo, M C; Oh, G-J; Han, J; Lee, S W; Park, M; Chang, W H; Shin, Y-I; Kim, Y-H

2016-11-01

We investigated the effect of stress hyperglycemia on the functional outcomes of non-diabetic hemorrhagic stroke. In addition, we investigated the usefulness of intensive rehabilitation for improving functional outcomes in patients with stress hyperglycemia. Non-diabetic hemorrhagic stroke patients were recruited and divided into two groups: intracerebral hemorrhage (ICH) (n = 165) and subarachnoid hemorrhage (SAH) (n = 156). Each group was divided into non-diabetics with or without stress hyperglycemia. Functional assessments were performed at 7 days and 3, 6 and 12 months after stroke onset. The non-diabetic with stress hyperglycemia groups were again divided into two groups who either received or did not receive intensive rehabilitation treatment. Serial functional outcome was compared between groups. For the ICH group, patients with stress hyperglycemia had worse modified Rankin Scale, National Institutes of Health Stroke Scale, Functional Ambulatory Category and Korean Mini-Mental State Examination scores than patients without stress hyperglycemia. For the SAH group, patients with stress hyperglycemia had worse scores on all functional assessments than patients without stress hyperglycemia at all time-points. After intensive rehabilitation treatment of patients with stress hyperglycemia, the ICH group had better scores on Functional Ambulatory Category and the SAH group had better scores on all functional assessments than patients without intensive rehabilitation treatment. Stress hyperglycemia affects the long-term prognosis of non-diabetic hemorrhagic stroke patients. Among stress hyperglycemia patients, intensive rehabilitation can enhance functional improvement after stroke. © 2016 EAN.

Regression analysis and transfer function in estimating the parameters of central pulse waves from brachial pulse wave.

Science.gov (United States)

Chai Rui; Li Si-Man; Xu Li-Sheng; Yao Yang; Hao Li-Ling

2017-07-01

This study mainly analyzed the parameters such as ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO) and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. These parameters extracted from the central pulse wave invasively measured were compared with the parameters measured from the brachial pulse waves by a regression model and a transfer function model. The accuracy of the parameters which were estimated by the regression model and the transfer function model was compared too. Our findings showed that in addition to the k value, the above parameters of the central pulse wave and the brachial pulse wave invasively measured had positive correlation. Both the regression model parameters including A_slope, DBP, SEVR and the transfer function model parameters had good consistency with the parameters invasively measured, and they had the same effect of consistency. The regression equations of the three parameters were expressed by Y'=a+bx. The SBP, PP, SV, CO of central pulse wave could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

Evaluation of Geometrical Modulation Transfer Function in Optical Lens System

Directory of Open Access Journals (Sweden)

Cheng-Mu Tsai

2015-01-01

Full Text Available This paper presents ray tracing algorithms to evaluate the geometrical modulation transfer function (GMTF of optical lens system. There are two kinds of ray tracings methods that can be applied to help simulate the point spread function (PSF in the image plane, for example, paraxial optics and real ray tracings. The paraxial optics ray tracing is used to calculate the first-order properties such as the effective focal length (EFL and the entrance pupil position through less cost of computation. However, the PSF could have a large tolerance by only using paraxial optics ray tracing for simulation. Some formulas for real ray tracing are applied in the sagittal and tangential line spread function (LSF. The algorithms are developed to demonstrate the simulation of LSF. Finally, the GMTF is evaluated after the fast Fourier transform (FFT of the LSF.

Parametric peak stress functions of 90o pipe bends with ovality under steady-state creep conditions

International Nuclear Information System (INIS)

Yaghi, A.H.; Hyde, T.H.; Becker, A.A.; Sun, W.

2009-01-01

Stress-based life prediction techniques are commonly used to estimate the failure life of pressurised pipe-related components, such as welds and bends, under creep conditions. Previous research has shown that reasonable life predictions can be obtained, based on the steady-state peak stresses, compared with the life predictions obtained from creep damage modelling. In this work, a series of parametric steady-state peak rupture stress functions of right-angled pipe bends with ovality are presented, which are based on the results obtained from finite element (FE) analyses, covering a number of material property and geometry parameters in practical ranges. Methods used to determine the stress functions are described. The FE analyses have been performed using axisymmetric models, subjected to internal pressure only, with a Norton creep law. Typical examples of parametric peak stress curve fitting are shown. In particular, the accuracy of the interpolation and extrapolation abilities of the stress functions is assessed. The results show that in most cases the interpolated and extrapolated peak stresses are accurate to within ±3% and ±5%, respectively.

Uncertainty of Monetary Valued Ecosystem Services - Value Transfer Functions for Global Mapping.

Directory of Open Access Journals (Sweden)

Stefan Schmidt

Full Text Available Growing demand of resources increases pressure on ecosystem services (ES and biodiversity. Monetary valuation of ES is frequently seen as a decision-support tool by providing explicit values for unconsidered, non-market goods and services. Here we present global value transfer functions by using a meta-analytic framework for the synthesis of 194 case studies capturing 839 monetary values of ES. For 12 ES the variance of monetary values could be explained with a subset of 93 study- and site-specific variables by utilizing boosted regression trees. This provides the first global quantification of uncertainties and transferability of monetary valuations. Models explain from 18% (water provision to 44% (food provision of variance and provide statistically reliable extrapolations for 70% (water provision to 91% (food provision of the terrestrial earth surface. Although the application of different valuation methods is a source of uncertainty, we found evidence that assuming homogeneity of ecosystems is a major error in value transfer function models. Food provision is positively correlated with better life domains and variables indicating positive conditions for human well-being. Water provision and recreation service show that weak ownerships affect valuation of other common goods negatively (e.g. non-privately owned forests. Furthermore, we found support for the shifting baseline hypothesis in valuing climate regulation. Ecological conditions and societal vulnerability determine valuation of extreme event prevention. Valuation of habitat services is negatively correlated with indicators characterizing less favorable areas. Our analysis represents a stepping stone to establish a standardized integration of and reporting on uncertainties for reliable and valid benefit transfer as an important component for decision support.

Effect of Mindfulness Meditation on Perceived Stress Scores and Autonomic Function Tests of Pregnant Indian Women.

Science.gov (United States)

Muthukrishnan, Shobitha; Jain, Reena; Kohli, Sangeeta; Batra, Swaraj

2016-04-01

Various pregnancy complications like hypertension, preeclampsia have been strongly correlated with maternal stress. One of the connecting links between pregnancy complications and maternal stress is mind-body intervention which can be part of Complementary and Alternative Medicine (CAM). Biologic measures of stress during pregnancy may get reduced by such interventions. To evaluate the effect of Mindfulness meditation on perceived stress scores and autonomic function tests of pregnant Indian women. Pregnant Indian women of 12 weeks gestation were randomised to two treatment groups: Test group with Mindfulness meditation and control group with their usual obstetric care. The effect of Mindfulness meditation on perceived stress scores and cardiac sympathetic functions and parasympathetic functions (Heart rate variation with respiration, lying to standing ratio, standing to lying ratio and respiratory rate) were evaluated on pregnant Indian women. There was a significant decrease in perceived stress scores, a significant decrease of blood pressure response to cold pressor test and a significant increase in heart rate variability in the test group (pwomen. The results of this study suggest that mindfulness meditation improves parasympathetic functions in pregnant women and is a powerful modulator of the sympathetic nervous system during pregnancy.

Family Stress and Adolescents’ Cognitive Functioning: Sleep as a Protective Factor

Science.gov (United States)

El-Sheikh, Mona; Tu, Kelly M.; Erath, Stephen A.; Buckhalt, Joseph A.

2014-01-01

We examined two sleep-wake parameters as moderators of the associations between exposure to family stressors and adolescent cognitive functioning. Participants were 252 school-recruited adolescents (M = 15.79 years; 66% European American, 34% African American). Youths reported on three dimensions of family stress: marital conflict, harsh parenting, and parental psychological control. Cognitive functioning was indexed through performance on the Woodcock-Johnson III Tests of Cognitive Abilities. Sleep minutes and efficiency were measured objectively using actigraphy. Towards identifying unique effects, path models controlled for two family stress variables while estimating the third. Analyses revealed that sleep efficiency moderated the associations between negative parenting (harsh parenting and parental psychological control) and adolescents’ cognitive functioning. The highest level of cognitive performance was predicted for adolescents with higher levels of sleep efficiency in conjunction with lower levels of either harsh parenting or psychological control. The effects of sleep were more pronounced at lower levels of negative parenting where adolescents with higher sleep efficiency performed better than their counterparts with poorer sleep. At higher levels of either harsh parenting or psychological control, similar levels of cognitive performance were observed regardless of sleep. Results are discussed in comparison to other recent studies on interrelations among family stress, sleep, and cognitive performance in childhood and adolescence. PMID:25329625

A new radiative transfer scattering phase function discretisation approach with inherent energy conservation

CSIR Research Space (South Africa)

Roos, TH

2014-06-01

Full Text Available large sphere scattering phase function distributions of interest for packed bed radiative heat transfer: the analytic distribution for a diffusely reflecting sphere (a backscattering test case) and the distribution for a transparent sphere (n = 1...

a Middle-Ear Reverse Transfer Function Computed from Vibration Measurements of Otoacoustic Emissions on the Ear Drum of the Guinea PIG

Science.gov (United States)

Dalhoff, Ernst; Turcanu, Diana; Gummer, Anthony W.

2009-02-01

Using distortion products measured as vibration of the umbo and as sound pressure in the ear canal of guinea pigs, we calculated the corresponding reverse transfer function. We compare the measurements with a middle-ear model taken from the literature and adapted to the guinea pig. A reasonable fit could be achieved. We conclude that the reverse transfer function will be useful to aid fitting a middle-ear model to measured transfer functions of human subjects.

An analytical wall-function for turbulent flows and heat transfer over rough walls

International Nuclear Information System (INIS)

Suga, K.; Craft, T.J.; Iacovides, H.

2006-01-01

This paper reports the development of a refined wall-function strategy for the modelling of turbulent forced convection heat transfer over smooth and rough surfaces. In order to include the effects of fine-grain surface roughness, the present study extends a more fundamental work by Craft et al. [Craft, T.J., Gerasimov, A.V., Iacovides, H., Launder, B.E., 2002. Progress in the generalisation of wall-function treatment. Int. J. Heat Fluid Flow 23, 148-160] on the development of advanced wall-functions of general applicability. The presently proposed model is validated through comparisons with data available for internal flows through channels and for external flows over flat and curved plates with both smooth and rough surfaces. Then, its further validation in separating flows over a sand dune and a sand-roughened ramp is discussed. The validation results suggest that the presently proposed form can be successfully applied to a wide range of attached and separated turbulent flows with heat transfer over smooth and fine-grain rough surfaces

The effect of surgical and psychological stress on learning and memory function in aged C57BL/6 mice.

Science.gov (United States)

Zhang, C; Li, C; Xu, Z; Zhao, S; Li, P; Cao, J; Mi, W

2016-04-21

Postoperative cognitive dysfunction (POCD) is an important complication following major surgery and general anesthesia in older patients. However, the etiology of POCD remains largely to be determined. It is unknown how surgical stress and psychological stress affect the postoperative learning and memory function in geriatric patients. We therefore established a pre-clinical model in aged C57BL/6 mice and aimed to investigate the effects of surgical stress and psychological stress on learning and memory function and the possible roles of the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway. The surgical stress was induced by abdominal surgery under local anesthesia, and the psychological stress was induced by a communication box. Cognitive functions and markers of the AKT/mTOR pathway were assessed at 1, 3 and 7 days following the stress. The impairments of learning and memory function existed for up to 7 days following surgical stress and surgical stress plus psychological stress, whereas the psychological stress did not affect the cognitive function alone or combined with surgical stress. Analysis of brain tissue revealed a significant involvement of the AKT/mTOR pathway in the impairment of cognition. These data suggested that surgical stress could induce cognitive impairment in aged mice and perioperative psychological stress is not a constitutive factor of POCD. The AKT/mTOR pathway is likely involved as one of the underlying mechanisms of the development of POCD. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

The Derived Transfer and Reversal of Mood Functions through Equivalence Relations: II

Science.gov (United States)

Cahill, Jane; Barnes-Holmes, Yvonne; Barnes-Holmes, Dermot; Rodriguez-Valverde, Miguel; Luciano, Carmen; Smeets, Paul M.

2007-01-01

Recent research has demonstrated the transfer of induced mood functions through equivalence relations by means of a musical mood-induction procedure. The research described in this article replicated and extended such work, primarily with the inclusion of a baseline and two types of reversal procedures. First, 16 adult participants were trained…

Evaluation of a functional medicine approach to treating fatigue, stress, and digestive issues in women.

Science.gov (United States)

Cutshall, Susanne M; Bergstrom, Larry R; Kalish, Daniel J

2016-05-01

Fatigue, stress, and digestive disorders are common among adults, especially women. We conducted a 28-week pilot study to assess the efficacy of a functional medicine approach to improving stress, energy, fatigue, digestive issues, and quality of life in middle-aged women. Findings showed significant improvements in many stress, fatigue, and quality-of-life measures. The treatment program increased mean salivary dehydroepiandrosterone levels and the cortisol-dehydroepiandrosterone ratio. Stool sample analyses suggested that these treatments reduced Helicobacter pylori infections. This study suggests that functional medicine may be an effective approach to managing stress and gastrointestinal symptoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Psychological and psychobiological stress in the relationship between basic cognitive function and school performance

Directory of Open Access Journals (Sweden)

Eugenia Fernández-Martín

2015-01-01

Full Text Available This study analyses the role played by daily stress, assessed through self-report and at the psychobiological level, in relation to basic cognitive function when predicting school performance. The sample comprised 100 schoolchildren (55 girls and 45 boys, age range 8 to 11 years from a state school in the city of Malaga (Spain. Daily stress was assessed through the Children's Daily Stress Inventory (IIEC m Spanish; Tnanes et al., 2009. Psychobiological stress was measured through the cortisol/DHEAS ratio, derived from saliva samples taken in the morning on two consecutive days. Basic cognitive skills were assessed by means of the Computerized Cognitive Assessment System (CDR battery; Wesnes et al., 2003, 2000. Finally, the measure of school performance was the mean value of the final grades recorded in the child's school report. In addition to descriptive and correlational statistical analyses, multiple regression analyses were conducted in order to assess the model. The results show that children's daily stress self-reported contributes to predict school performance, and has proven to be more influential than basic cognitive function when it comes to predict school performance. Therefore, in order to achieve good school performance, a pupil not only requires good basic cognitive function, but must also present low levels of self-reported daily stress. These findings suggest a new way of explaining and predicting school failure.

Four-point correlation function of stress-energy tensors in N=4 superconformal theories

CERN Document Server

Korchemsky, G P

2015-01-01

We derive the explicit expression for the four-point correlation function of stress-energy tensors in four-dimensional N=4 superconformal theory. We show that it has a remarkably simple and suggestive form allowing us to predict a large class of four-point correlation functions involving the stress-energy tensor and other conserved currents. We then apply the obtained results on the correlation functions to computing the energy-energy correlations, which measure the flow of energy in the final states created from the vacuum by a source. We demonstrate that they are given by a universal function independent of the choice of the source. Our analysis relies only on N=4 superconformal symmetry and does not use the dynamics of the theory.

Work stress, anthropometry, lung function, blood pressure, and blood-based biomarkers

DEFF Research Database (Denmark)

Magnusson Hanson, Linda L.; Westerlund, Hugo; Goldberg, Marcel

2017-01-01

-based biomarkers. Linear regression analyses before and after multivariable adjustment for age, socioeconomic status, depressive symptoms, health-related behaviours, and chronic conditions showed that work stress was associated with higher BMI, waist circumference, waist-hip ratio, alanine transaminase, white......Work stress is a risk factor for cardio-metabolic diseases, but few large-scale studies have examined the clinical profile of individuals with work stress. To address this limitation, we conducted a cross-sectional study including 43,593 working adults from a French population-based sample aged 18......–72 years (the CONSTANCES cohort). According to the Effort-Reward Imbalance model, work stress was defined as an imbalance between perceived high efforts and low rewards at work. A standardized health examination included measures of anthropometry, lung function, blood pressure and standard blood...

A Meta-Analysis Detailing Overall Sexual Function and Orgasmic Function in Women Undergoing Midurethral Sling Surgery for Stress Incontinence

Directory of Open Access Journals (Sweden)

Nicole Szell, DO

2017-06-01

Szell N, Komisaruk B, Goldstein SW, et al. A Meta-Analysis Detailing Overall Sexual Function and Orgasmic Function in Women Undergoing Midurethral Sling Surgery for Stress Incontinence. Sex Med 2017;5:e84–e93.

The aftermath of terrorism: posttraumatic stress and functional impairment after the 2011 Oslo bombing.

Science.gov (United States)

Solberg, Øivind; Blix, Ines; Heir, Trond

2015-01-01

In the present study we wanted to investigate the link between exposure, posttraumatic stress symptomatology, and functional impairment in the aftermath of terrorism. Posttraumatic stress symptomatology and functional impairment related to the Oslo bombing 22nd of July, 2011, in directly and indirectly exposed individuals (N = 1927) were assessed together with demographics, exposure, peri-traumatic reactions, and event centrality approximately 1 year after the attack. Directly and indirectly exposed individuals qualifying for posttraumatic stress disorder (PTSD) reported similar peri-traumatic reactions, event centrality, and functional impairment. However, clusters within the PTSD symptomatology were differentially associated with impairment as a function of their exposure. In the directly exposed group, all clusters within the PTSD symptomatology were associated with impairment in function, while only emotional numbing was associated with impairment within the indirectly exposed group. Considering that terror attacks frequently involve directly exposed individuals and a larger population of indirectly exposed individuals, this finding is of importance, especially in the design of intervention programs and the development of treatment policies.

Realization of Nth-Order Voltage Transfer Function using Current Conveyors CCII

Directory of Open Access Journals (Sweden)

K. Vrba

1997-06-01

Full Text Available A universal method for the realization of arbitrary voltage transfer function in canonic form is presented. A voltage-controlled current-source using a plus-type second-generation current conveyor is here applied as the basic building element. Filters designed according to this method have a high input impedance and low sensitivity to variations of circuit parameters. All passive elements are grounded.

Lipid lowering and HDL raising gene transfer increase endothelial progenitor cells, enhance myocardial vascularity, and improve diastolic function.

Directory of Open Access Journals (Sweden)

Stephanie C Gordts

Full Text Available BACKGROUND: Hypercholesterolemia and low high density lipoprotein (HDL cholesterol contribute to coronary heart disease but little is known about their direct effects on myocardial function. Low HDL and raised non-HDL cholesterol levels carried increased risk for heart failure development in the Framingham study, independent of any association with myocardial infarction. The objective of this study was to test the hypothesis that increased endothelial progenitor cell (EPC number and function after lipid lowering or HDL raising gene transfer in C57BL/6 low density lipoprotein receptor deficient (LDLr(-/- mice may be associated with an enhanced relative vascularity in the myocardium and an improved cardiac function. METHODOLOGY/PRINCIPAL FINDINGS: Lipid lowering and HDL raising gene transfer were performed using the E1E3E4-deleted LDLr expressing adenoviral vector AdLDLr and the human apolipoprotein A-I expressing vector AdA-I, respectively. AdLDLr transfer in C57BL/6 LDLr(-/- mice resulted in a 2.0-fold (p<0.05 increase of the circulating number of EPCs and in an improvement of EPC function as assessed by ex vivo EPC migration and EPC adhesion. Capillary density and relative vascularity in the myocardium were 28% (p<0.01 and 22% (p<0.05 higher, respectively, in AdLDLr mice compared to control mice. The peak rate of isovolumetric relaxation was increased by 12% (p<0.05 and the time constant of isovolumetric relaxation was decreased by 14% (p<0.05 after AdLDLr transfer. Similarly, HDL raising gene transfer increased EPC number and function and raised both capillary density and relative vascularity in the myocardium by 24% (p<0.05. The peak rate of isovolumetric relaxation was increased by 16% (p<0.05 in AdA-I mice compared to control mice. CONCLUSIONS/SIGNIFICANCE: Both lipid lowering and HDL raising gene transfer have beneficial effects on EPC biology, relative myocardial vascularity, and diastolic function. These findings raise concerns over the

Circadian Clocks and the Interaction between Stress Axis and Adipose Function

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Isa Kolbe

2015-01-01

Full Text Available Many physiological processes and most endocrine functions show fluctuations over the course of the day. These so-called circadian rhythms are governed by an endogenous network of cellular clocks and serve as an adaptation to daily and, thus, predictable changes in the organism’s environment. Circadian clocks have been described in several tissues of the stress axis and in adipose cells where they regulate the rhythmic and stimulated release of stress hormones, such as glucocorticoids, and various adipokine factors. Recent work suggests that both adipose and stress axis clock systems reciprocally influence each other and adrenal-adipose rhythms may be key players in the development and therapy of metabolic disorders. In this review, we summarize our current understanding of adrenal and adipose tissue rhythms and clocks and how they might interact to regulate energy homoeostasis and stress responses under physiological conditions. Potential chronotherapeutic strategies for the treatment of metabolic and stress disorders are discussed.

[Development and technological transfer of functional pastas extended with legumes].

Science.gov (United States)

Granito, Marisela; Ascanio, Vanesa

2009-03-01

Development and technological transfer of functional pastas extended with legumes. Semolina pasta is a highly consumed foodstuff, the biological value of which is low because its protein is deficient in lysine. However, if the semolina is extended with legumes rich in this essential aminoacid, not only and aminoacid supplementation is produced, but also the dietary fibre and minerals are increased. In this work, pastas extended in 10% with a white variety of Phaseolus vulgaris and with Cajanus cajan were produced on a pilot plant scale, and this technology was transferred to a cooperative producing artisanal pastas. The cooking qualities and the physical, chemical, and nutritional characteristics of the pastas were evaluated, as well as the sensorial acceptability in institutionalized elderly people. The extension of the pastas with legume flours increased the optimum cooking time (15 to 20%), the weight (20% and 25%), and the loss of solids by cooking. Similarly, the functional value of the pastas increased by increasing the contents of minerals and dietary fibre. The protein content, as well as the protein digestibility in vitro also increased; however, the parameters of colour L, a and b, and the total starch content of the pastas decreased. At consumer level, the pastas extended with legumes had a good acceptability, for what it was concluded that the extension of the semolina with legume flours in the manufacture of pastas is technologically feasible.

Oxidative stress, neuroendocrine function and behavior in an animal model of extended longevity

NARCIS (Netherlands)

Berry, Alessandra

2010-01-01

Stress and oxidative stress (OS) might act synergistically to exacerbate the neuronal decay associated with aging. Recent evidence has shown a redox regulation of the function of the glucocorticoid receptors as nuclear transcription factors. The lack of the p66Shc gene reduces OS and increases

Cumulant generating function formula of heat transfer in ballistic systems with lead-lead coupling

Science.gov (United States)

Li, Huanan; Agarwalla, Bijay Kumar; Wang, Jian-Sheng

2012-10-01

Based on a two-time observation protocol, we consider heat transfer in a given time interval tM in a lead-junction-lead system taking coupling between the leads into account. In view of the two-time observation, consistency conditions are carefully verified in our specific family of quantum histories. Furthermore, its implication is briefly explored. Then using the nonequilibrium Green's function method, we obtain an exact formula for the cumulant generating function for heat transfer between the two leads, valid in both transient and steady-state regimes. Also, a compact formula for the cumulant generating function in the long-time limit is derived, for which the Gallavotti-Cohen fluctuation symmetry is explicitly verified. In addition, we briefly discuss Di Ventra's repartitioning trick regarding whether the repartitioning procedure of the total Hamiltonian affects the nonequilibrium steady-state current fluctuation. All kinds of properties of nonequilibrium current fluctuations, such as the fluctuation theorem in different time regimes, could be readily given according to these exact formulas.

The calculation of the viscosity from the autocorrelation function using molecular and atomic stress tensors

Science.gov (United States)

Cui, S. T.

The stress-stress correlation function and the viscosity of a united-atom model of liquid decane are studied by equilibrium molecular dynamics simulation using two different formalisms for the stress tensor: the atomic and the molecular formalisms. The atomic and molecular correlation functions show dramatic difference in short-time behaviour. The integrals of the two correlation functions, however, become identical after a short transient period whichis significantly shorter than the rotational relaxation time of the molecule. Both reach the same plateau value in a time period corresponding to this relaxation time. These results provide a convenient guide for the choice of the upper integral time limit in calculating the viscosity by the Green-Kubo formula.

Cognitive reserve and self-efficacy as moderators of the relationship between stress exposure and executive functioning among spousal dementia caregivers.

Science.gov (United States)

Pertl, M M; Hannigan, C; Brennan, S; Robertson, I H; Lawlor, B A

2017-04-01

A substantial literature has reported that stress negatively impacts on cognitive processes. As dementia caregiving can be stressful, it has been hypothesized that the challenges of dementia care may increase caregivers' own vulnerability to cognitive decline. Prefrontal processes are thought to be most vulnerable to stress; however, few studies have examined whether greater caregiver stress predicts poorer executive dysfunction, and no previous research has considered potential moderators of this relationship. We examined (1) whether greater psychological stress mediated a relationship between caregiver stress exposure and executive functioning and (2) whether greater self-efficacy and cognitive reserve (CR) moderated this relationship. Spousal dementia caregivers (n = 253) completed the Neuropsychiatric Inventory Questionnaire (stress exposure), the Perceived Stress Scale, the National Adult Reading Test (CR), the Fortinsky dementia-specific caregiver self-efficacy scale, and the Color Trails Test (executive functioning). Moderated mediation was tested using the PROCESS macro. Age, gender, and dementia risk factors were included as covariates. Greater stress exposure indirectly predicted executive functioning through psychological stress. Stronger relationships between greater psychological stress and poorer executive functioning were observed among caregivers with lower CR; there was no evidence that self-efficacy moderated the relationship between stress exposure and psychological stress. Our findings are in line with the idea that greater psychological stress in response to challenges associated with dementia care predicts poorer caregiver executive functioning, particularly among caregivers with low CR. However, these findings are cross sectional; it is also possible that poorer executive functioning contributes to greater caregiver stress.

Lateralized kappa opioid receptor signaling from the amygdala central nucleus promotes stress-induced functional pain.

Science.gov (United States)

Nation, Kelsey M; De Felice, Milena; Hernandez, Pablo I; Dodick, David W; Neugebauer, Volker; Navratilova, Edita; Porreca, Frank

2018-05-01

The response of diffuse noxious inhibitory controls (DNIC) is often decreased, or lost, in stress-related functional pain syndromes. Because the dynorphin/kappa opioid receptor (KOR) pathway is activated by stress, we determined its role in DNIC using a model of stress-induced functional pain. Male, Sprague-Dawley rats were primed for 7 days with systemic morphine resulting in opioid-induced hyperalgesia. Fourteen days after priming, when hyperalgesia was resolved, rats were exposed to environmental stress and DNIC was evaluated by measuring hind paw response threshold to noxious pressure (test stimulus) after capsaicin injection in the forepaw (conditioning stimulus). Morphine priming without stress did not alter DNIC. However, stress produced a loss of DNIC in morphine-primed rats in both hind paws that was abolished by systemic administration of the KOR antagonist, nor-binaltorphimine (nor-BNI). Microinjection of nor-BNI into the right, but not left, central nucleus of the amygdala (CeA) prevented the loss of DNIC in morphine-primed rats. Diffuse noxious inhibitory controls were not modulated by bilateral nor-BNI in the rostral ventromedial medulla. Stress increased dynorphin content in both the left and right CeA of primed rats, reaching significance only in the right CeA; no change was observed in the rostral ventromedial medulla or hypothalamus. Although morphine priming alone is not sufficient to influence DNIC, it establishes a state of latent sensitization that amplifies the consequences of stress. After priming, stress-induced dynorphin/KOR signaling from the right CeA inhibits DNIC in both hind paws, likely reflecting enhanced descending facilitation that masks descending inhibition. Kappa opioid receptor antagonists may provide a new therapeutic strategy for stress-related functional pain disorders.

Structure, function and networks of transcription factors involved in abiotic stress responses

DEFF Research Database (Denmark)

Lindemose, Søren; O'Shea, Charlotte; Jensen, Michael Krogh

2013-01-01

Transcription factors (TFs) are master regulators of abiotic stress responses in plants. This review focuses on TFs from seven major TF families, known to play functional roles in response to abiotic stresses, including drought, high salinity, high osmolarity, temperature extremes...... and the phytohormone ABA. Although ectopic expression of several TFs has improved abiotic stress tolerance in plants, fine-tuning of TF expression and protein levels remains a challenge to avoid crop yield loss. To further our understanding of TFs in abiotic stress responses, emerging gene regulatory networks based...... on TFs and their direct targets genes are presented. These revealed components shared between ABA-dependent and independent signaling as well as abiotic and biotic stress signaling. Protein structure analysis suggested that TFs hubs of large interactomes have extended regions with protein intrinsic...

Transfer function between EEG and BOLD signals of epileptic activity

Directory of Open Access Journals (Sweden)

Marco eLeite

2013-01-01

Full Text Available Simultaneous EEG-fMRI recordings have seen growing application in the evaluation of epilepsy, namely in the characterization of brain networks related to epileptic activity. In EEG-correlated fMRI studies, epileptic events are usually described as boxcar signals based on the timing information retrieved from the EEG, and subsequently convolved with a heamodynamic response function to model the associated BOLD changes. Although more flexible approaches may allow a higher degree of complexity for the haemodynamics, the issue of how to model these dynamics based on the EEG remains an open question. In this work, a new methodology for the integration of simultaneous EEG-fMRI data in epilepsy is proposed, which incorporates a transfer function from the EEG to the BOLD signal. Independent component analysis (ICA of the EEG is performed, and a number of metrics expressing different models of the EEG-BOLD transfer function are extracted from the resulting time courses. These metrics are then used to predict the fMRI data and to identify brain areas associated with the EEG epileptic activity. The methodology was tested on both ictal and interictal EEG-fMRI recordings from one patient with a hypothalamic hamartoma. When compared to the conventional analysis approach, plausible, consistent and more significant activations were obtained. Importantly, frequency-weighted EEG metrics yielded superior results than those weighted solely on the EEG power, which comes in agreement with previous literature. Reproducibility, specificity and sensitivity should be addressed in an extended group of patients in order to further validate the proposed methodology and generalize the presented proof of concept.

Fetal Programming of Body Composition, Obesity, and Metabolic Function: The Role of Intrauterine Stress and Stress Biology

Directory of Open Access Journals (Sweden)

Sonja Entringer

2012-01-01

Full Text Available Epidemiological, clinical, physiological, cellular, and molecular evidence suggests that the origins of obesity and metabolic dysfunction can be traced back to intrauterine life and supports an important role for maternal nutrition prior to and during gestation in fetal programming. The elucidation of underlying mechanisms is an area of interest and intense investigation. In this perspectives paper we propose that in addition to maternal nutrition-related processes it may be important to concurrently consider the potential role of intrauterine stress and stress biology. We frame our arguments in the larger context of an evolutionary-developmental perspective that supports roles for both nutrition and stress as key environmental conditions driving natural selection and developmental plasticity. We suggest that intrauterine stress exposure may interact with the nutritional milieu, and that stress biology may represent an underlying mechanism mediating the effects of diverse intrauterine perturbations, including but not limited to maternal nutritional insults (undernutrition and overnutrition, on brain and peripheral targets of programming of body composition, energy balance homeostasis, and metabolic function. We discuss putative maternal-placental-fetal endocrine and immune/inflammatory candidate mechanisms that may underlie the long-term effects of intrauterine stress. We conclude with a commentary of the implications for future research and clinical practice.

The influence of electric charge transferred during electro-mechanical reshaping on mechanical behavior of cartilage

Science.gov (United States)

Protsenko, Dimitry E.; Lim, Amanda; Wu, Edward C.; Manuel, Cyrus; Wong, Brian J. F.

2011-03-01

Electromechanical reshaping (EMR) of cartilage has been suggested as an alternative to the classical surgical techniques of modifying the shape of facial cartilages. The method is based on exposure of mechanically deformed cartilaginous tissue to a low level electric field. Electro-chemical reactions within the tissue lead to reduction of internal stress, and establishment of a new equilibrium shape. The same reactions offset the electric charge balance between collagen and proteoglycan matrix and interstitial fluid responsible for maintenance of cartilage mechanical properties. The objective of this study was to investigate correlation between the electric charge transferred during EMR and equilibrium elastic modulus. We used a finite element model based on the triphasic theory of cartilage mechanical properties to study how electric charges transferred in the electro-chemical reactions in cartilage can change its mechanical responses to step displacements in unconfined compression. The concentrations of the ions, the strain field and the fluid and ion velocities within the specimen subject to an applied mechanical deformation were estimated and apparent elastic modulus (the ratio of the equilibrium axial stress to the axial strain) was calculated as a function of transferred charge. The results from numerical calculations showed that the apparent elastic modulus decreases with increase in electric charge transfer. To compare numerical model with experimental observation we measured elastic modulus of cartilage as a function of electric charge transferred in electric circuit during EMR. Good correlation between experimental and theoretical data suggests that electric charge disbalance is responsible for alteration of cartilage mechanical properties.

Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory.

Science.gov (United States)

Isegawa, Miho; Gao, Jiali; Truhlar, Donald G

2011-08-28

Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi-Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi-Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred. © 2011 American Institute of Physics

Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

International Nuclear Information System (INIS)

Tromp, R.M.; Schramm, S.M.

2013-01-01

The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C 3 -corrected microscopes it is well established that a small negative value of C 3 , offset by positive values of C 5 and defocus C 1 results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C 1 and C 3 . We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed

A note on G-functions within the scope of radiative transfer in turbid vegetation media

International Nuclear Information System (INIS)

Otto, Sebastian; Trautmann, Thomas

2008-01-01

This work reports on the use of leaf normal distribution functions (LNDFs) in the radiative transfer theory of turbid vegetation media to calculate the so-called G-function (GF). We revisit the normalisation condition of the LNDFs and present an extended set of fully explicit analytical expressions for GF considering commonly used standard LNDFs from purely vertical to purely horizontal model leaves. Applying them we derive GF for a generalised LNDF, which is written as a series of cosine functions with a number of free parameters. This generalisation opens up the possibility to fit leaf orientation measurements to our generalised LNDF and to determine the respective analytical GF. Thus, an extended range of leaf architectures, beyond the usual and less realistic standard LNDFs, can be considered with respect to applications of the radiative transfer theory in turbid vegetation media

Influence of wall couple stress in MHD flow of a micropolar fluid in a porous medium with energy and concentration transfer

Science.gov (United States)

Khalid, Asma; Khan, Ilyas; Khan, Arshad; Shafie, Sharidan

2018-06-01

The intention here is to investigate the effects of wall couple stress with energy and concentration transfer in magnetohydrodynamic (MHD) flow of a micropolar fluid embedded in a porous medium. The mathematical model contains the set of linear conservation forms of partial differential equations. Laplace transforms and convolution technique are used for computation of exact solutions of velocity, microrotations, temperature and concentration equations. Numerical values of skin friction, couple wall stress, Nusselt and Sherwood numbers are also computed. Characteristics for the significant variables on the physical quantities are graphically discussed. Comparison with previously published work in limiting sense shows an excellent agreement.

The Application of Normal Stress Reduction Function in Tilt Tests for Different Block Shapes

Science.gov (United States)

Kim, Dong Hyun; Gratchev, Ivan; Hein, Maw; Balasubramaniam, Arumugam

2016-08-01

This paper focuses on the influence of the shapes of rock cores, which control the sliding or toppling behaviours in tilt tests for the estimation of rock joint roughness coefficients (JRC). When the JRC values are estimated by performing tilt tests, the values are directly proportional to the basic friction of the rock material and the applied normal stress on the sliding planes. Normal stress obviously varies with the shape of the sliding block, and the basic friction angle is also affected by the sample shapes in tilt tests. In this study, the shapes of core blocks are classified into three representative shapes and those are created using plaster. Using the various shaped artificial cores, a set of tilt tests is carried out to identify the shape influences on the normal stress and the basic friction angle in tilt tests. The test results propose a normal stress reduction function to estimate the normal stress for tilt tests according to the sample shapes based on Barton's empirical equation. The proposed normal stress reduction functions are verified by tilt tests using artificial plaster joints and real rock joint sets. The plaster joint sets are well matched and cast in detailed printed moulds using a 3D printing technique. With the application of the functions, the obtained JRC values from the tilt tests using the plaster samples and the natural rock samples are distributed within a reasonable JRC range when compared with the measured values.

Blunted amygdala functional connectivity during a stress task in alcohol dependent individuals: A pilot study.

Science.gov (United States)

Wade, Natasha E; Padula, Claudia B; Anthenelli, Robert M; Nelson, Erik; Eliassen, James; Lisdahl, Krista M

2017-12-01

Scant research has been conducted on neural mechanisms underlying stress processing in individuals with alcohol dependence (AD). We examined neural substrates of stress in AD individuals compared with controls using an fMRI task previously shown to induce stress, assessing amygdala functional connectivity to medial prefrontal cortex (mPFC). For this novel pilot study, 10 abstinent AD individuals and 11 controls completed a modified Trier stress task while undergoing fMRI acquisition. The amygdala was used as a seed region for whole-brain seed-based functional connectivity analysis. After controlling for family-wise error (p = 0.05), there was significantly decreased left and right amygdala connectivity with frontal (specifically mPFC), temporal, parietal, and cerebellar regions. Subjective stress, but not craving, increased from pre-to post-task. This study demonstrated decreased connectivity between the amygdala and regions important for stress and emotional processing in long-term abstinent individuals with AD. These results suggest aberrant stress processing in individuals with AD even after lengthy periods of abstinence.

Spatial distribution measured by the modulation transfer function

International Nuclear Information System (INIS)

Rossi, P.; Brice, D.K.; Doyle, B.L.

2003-01-01

Spatial distributions in ion micro-beam and IBA experimental practice are regularly characterized through the parameters of FWHM and tail area percentage (TF, tail fraction). Linear and stationary transducer theory allows these distributions to be described in the Fourier-dual frequency space, and provides an indirect method to evaluate them through measurement of the modulation transfer function (MTF). We suggest direct measurement of MTF by employing bar pattern grids, similar to those used for calibration of radiological equipment. Assuming spatial distributions of the form exp(-(|αx|) η ), we are able to relate the MTF measurements to the more popular FWHM and TF. This new approach to determine spatial resolution can become a standard for use by the micro-beam community

Performance of the dot product function in radiative transfer code SORD

Science.gov (United States)

Korkin, Sergey; Lyapustin, Alexei; Sinyuk, Aliaksandr; Holben, Brent

2016-10-01

The successive orders of scattering radiative transfer (RT) codes frequently call the scalar (dot) product function. In this paper, we study performance of some implementations of the dot product in the RT code SORD using 50 scenarios for light scattering in the atmosphere-surface system. In the dot product function, we use the unrolled loops technique with different unrolling factor. We also considered the intrinsic Fortran functions. We show results for two machines: ifort compiler under Windows, and pgf90 under Linux. Intrinsic DOT_PRODUCT function showed best performance for the ifort. For the pgf90, the dot product implemented with unrolling factor 4 was the fastest. The RT code SORD together with the interface that runs all the mentioned tests are publicly available from ftp://maiac.gsfc.nasa.gov/pub/skorkin/SORD_IP_16B (current release) or by email request from the corresponding (first) author.

Heat transfer, velocity-temperature correlation, and turbulent shear stress from Navier-Stokes computations of shock wave/turbulent boundary layer interaction flows

Science.gov (United States)

Wang, C. R.; Hingst, W. R.; Porro, A. R.

1991-01-01

The properties of 2-D shock wave/turbulent boundary layer interaction flows were calculated by using a compressible turbulent Navier-Stokes numerical computational code. Interaction flows caused by oblique shock wave impingement on the turbulent boundary layer flow were considered. The oblique shock waves were induced with shock generators at angles of attack less than 10 degs in supersonic flows. The surface temperatures were kept at near-adiabatic (ratio of wall static temperature to free stream total temperature) and cold wall (ratio of wall static temperature to free stream total temperature) conditions. The computational results were studied for the surface heat transfer, velocity temperature correlation, and turbulent shear stress in the interaction flow fields. Comparisons of the computational results with existing measurements indicated that (1) the surface heat transfer rates and surface pressures could be correlated with Holden's relationship, (2) the mean flow streamwise velocity components and static temperatures could be correlated with Crocco's relationship if flow separation did not occur, and (3) the Baldwin-Lomax turbulence model should be modified for turbulent shear stress computations in the interaction flows.

Containment condensing heat transfer

International Nuclear Information System (INIS)

Gido, R.G.; Koestel, A.

1983-01-01

This report presents a mechanistic heat-transfer model that is valid for large scale containment heat sinks. The model development is based on the determination that the condensation is controlled by mass diffusion through the vapor-air boundary layer, and the application of the classic Reynolds' analogy to formulate expressions for the transfer of heat and mass based on hydrodynamic measurements of the momentum transfer. As a result, the analysis depends on the quantification of the shear stress (momentum transfer) at the interface between the condensate film and the vapor-air boundary layer. In addition, the currently used Tagami and Uchida test observations and their range of applicability are explained

Simultaneous fluid-flow, heat-transfer and solid-stress computation in a single computer code

Energy Technology Data Exchange (ETDEWEB)

Spalding, D B [Concentration Heat and Momentum Ltd, London (United Kingdom)

1998-12-31

Computer simulation of flow- and thermally-induced stresses in mechanical-equipment assemblies has, in the past, required the use of two distinct software packages, one to determine the forces and the temperatures, and the other to compute the resultant stresses. The present paper describes how a single computer program can perform both tasks at the same time. The technique relies on the similarity of the equations governing velocity distributions in fluids to those governing displacements in solids. The same SIMPLE-like algorithm is used for solving both. Applications to 1-, 2- and 3-dimensional situations are presented. It is further suggested that Solid-Fluid-Thermal, ie SFT analysis may come to replace CFD on the one hand and the analysis of stresses in solids on the other, by performing the functions of both. (author) 7 refs.

Simultaneous fluid-flow, heat-transfer and solid-stress computation in a single computer code

Energy Technology Data Exchange (ETDEWEB)

Spalding, D.B. [Concentration Heat and Momentum Ltd, London (United Kingdom)

1997-12-31

Computer simulation of flow- and thermally-induced stresses in mechanical-equipment assemblies has, in the past, required the use of two distinct software packages, one to determine the forces and the temperatures, and the other to compute the resultant stresses. The present paper describes how a single computer program can perform both tasks at the same time. The technique relies on the similarity of the equations governing velocity distributions in fluids to those governing displacements in solids. The same SIMPLE-like algorithm is used for solving both. Applications to 1-, 2- and 3-dimensional situations are presented. It is further suggested that Solid-Fluid-Thermal, ie SFT analysis may come to replace CFD on the one hand and the analysis of stresses in solids on the other, by performing the functions of both. (author) 7 refs.

Research Paper: Executive Functions in Students With Depression, Anxiety, and Stress Symptoms

Directory of Open Access Journals (Sweden)

Bita Ajilchi

2017-05-01

Conclusion: The findings of this research raised specific issues in relation to the role of depression, anxiety, and stress in the disruption of the executive functions of sufferers. Selective and shifting attention and cognitive abilities are specifically affected in this regard. Meanwhile, the role of stress in impairing decision making and the major role of anxiety in impairing sustained attention was shown to be considerable.

Study on application of green's function method in thermal stress rapid calculation

International Nuclear Information System (INIS)

Zhang Guihe; Duan Yuangang; Xu Xiao; Chen Rong

2013-01-01

This paper presents a quick and accuracy thermal stress calculation method, the Green's Function Method, which is a combination of finite element method and numerical algorithm method. Thermal stress calculation of Safe Injection Nozzle of Reactor Coolant Line of PWR plant is performed with Green's function method for heatup and cooldown thermal transients as a demonstration example, and the result is compared with finite element method to verify the rationality and accuracy of this method. The advantage and disadvantage of the Green's function method and the finite element method are also compared. (authors)

Intrinsic functional connectivity between amygdala and hippocampus during rest predicts enhanced memory under stress.

Science.gov (United States)

de Voogd, Lycia D; Klumpers, Floris; Fernández, Guillén; Hermans, Erno J

2017-01-01

Declarative memories of stressful events are less prone to forgetting than mundane events. Animal research has demonstrated that such stress effects on consolidation of hippocampal-dependent memories require the amygdala. In humans, it has been shown that during learning, increased amygdala-hippocampal interactions are related to more efficient memory encoding. Animal models predict that following learning, amygdala-hippocampal interactions are instrumental to strengthening the consolidation of such declarative memories. Whether this is the case in humans is unknown and remains to be empirically verified. To test this, we analyzed data from a sample of 120 healthy male participants who performed an incidental encoding task and subsequently underwent resting-state functional MRI in a stressful and a neutral context. Stress was assessed by measures of salivary cortisol, blood pressure, heart rate, and subjective ratings. Memory was tested afterwards outside of the scanner. Our data show that memory was stronger in the stress context compared to the neutral context and that stress-induced cortisol responses were associated with this memory enhancement. Interestingly, amygdala-hippocampal connectivity during post-encoding awake rest regardless of context (stress or neutral) was associated with the enhanced memory performance under stress. Thus, our findings are in line with a role for intrinsic functional connectivity during rest between the amygdala and the hippocampus in the state effects of stress on strengthening memory. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Exercise Intensity on Postexercise Endothelial Function and Oxidative Stress

Directory of Open Access Journals (Sweden)

Conor McClean

2015-01-01

Full Text Available Purpose. To measure endothelial function and oxidative stress immediately, 90 minutes, and three hours after exercise of varying intensities. Methods. Sixteen apparently healthy men completed three exercise bouts of treadmill running for 30 minutes at 55% V˙O2max (mild; 20 minutes at 75% V˙O2max (moderate; or 5 minutes at 100% V˙O2max (maximal in random order. Brachial artery flow-mediated dilation (FMD was assessed with venous blood samples drawn for measurement of endothelin-1 (ET-1, lipid hydroperoxides (LOOHs, and lipid soluble antioxidants. Results. LOOH increased immediately following moderate exercise (P0.05. Conclusions. Acute exercise at different intensities elicits varied effects on oxidative stress, shear rate, and ET-1 that do not appear to mediate changes in endothelial function measured by FMD.

Mechanical coupling between earthquakes and volcanoes inferred from stress transfer models: evidence from Vesuvio, Etna and Alban Hills (Italy)

Science.gov (United States)

Cocco, M.; Feuillet, N.; Nostro, C.; Musumeci, C.

2003-04-01

We investigate the mechanical interactions between tectonic faults and volcanic sources through elastic stress transfer and discuss the results of several applications to Italian active volcanoes. We first present the stress modeling results that point out a two-way coupling between Vesuvius eruptions and historical earthquakes in Southern Apennines, which allow us to provide a physical interpretation of their statistical correlation. Therefore, we explore the elastic stress interaction between historical eruptions at the Etna volcano and the largest earthquakes in Eastern Sicily and Calabria. We show that the large 1693 seismic event caused an increase of compressive stress along the rift zone, which can be associated to the lack of flank eruptions of the Etna volcano for about 70 years after the earthquake. Moreover, the largest Etna eruptions preceded by few decades the large 1693 seismic event. Our modeling results clearly suggest that all these catastrophic events are tectonically coupled. We also investigate the effect of elastic stress perturbations on the instrumental seismicity caused by magma inflation at depth both at the Etna and at the Alban Hills volcanoes. In particular, we model the seismicity pattern at the Alban Hills volcano (central Italy) during a seismic swarm occurred in 1989-90 and we interpret it in terms of Coulomb stress changes caused by magmatic processes in an extensional tectonic stress field. We verify that the earthquakes occur in areas of Coulomb stress increase and that their faulting mechanisms are consistent with the stress perturbation induced by the volcanic source. Our results suggest a link between faults and volcanic sources, which we interpret as a tectonic coupling explaining the seismicity in a large area surrounding the volcanoes.

Nonlinear transfer function encodes synchronization in a neural network from the mammalian brain.

Science.gov (United States)

Menendez de la Prida, L; Sanchez-Andres, J V

1999-09-01

Synchronization is one of the mechanisms by which the brain encodes information. The observed synchronization of neuronal activity has, however, several levels of fluctuations, which presumably regulate local features of specific areas. This means that biological neural networks should have an intrinsic mechanism able to synchronize the neuronal activity but also to preserve the firing capability of individual cells. Here, we investigate the input-output relationship of a biological neural network from developing mammalian brain, i.e., the hippocampus. We show that the probability of occurrence of synchronous output activity (which consists in stereotyped population bursts recorded throughout the hippocampus) is encoded by a sigmoidal transfer function of the input frequency. Under this scope, low-frequency inputs will not produce any coherent output while high-frequency inputs will determine a synchronous pattern of output activity (population bursts). We analyze the effect of the network size (N) on the parameters of the transfer function (threshold and slope). We found that sigmoidal functions realistically simulate the synchronous output activity of hippocampal neural networks. This outcome is particularly important in the application of results from neural network models to neurobiology.

A numerical solution to an inverse unsteady-state heat transfer problem involving the Trefftz functions

Directory of Open Access Journals (Sweden)

Maciejewska Beata

2017-01-01

Full Text Available This paper shows the results concerning flow boiling heat transfer in an asymmetrically heated vertical minichannel. The heated element for FC-72 Fluorinert flowing in that minichannel was a thin foil. The foil surface temperature was monitored continuously at 18 points by K-type thermocouples from the outer foil surface. Fluid temperature and pressure in the minichannel inlet and outlet, current supplied to the foil and voltage drop were also monitored. Measurements were carried out at 1 s intervals. The objective was to determine the heat transfer coefficient on the heated foil–fluid contact surface in the minichannel. It was obtained from the Robin boundary condition. The foil temperature was the result of solving the nonstationary two-dimensional inverse boundary problem in the heated foil. Using the FEM combined with Trefftz functions as basis functions solved the problem. The unknown temperature values at nodes were calculated by minimising the adequate functional. The values of local heat transfer coefficients were consistent with the results obtained by the authors in their previous studies when steady-state conditions were analysed. This time, however, these values were analysed as time dependent, which facilitated observation of coefficient changes that were impossible to observe under the steady-state conditions.

Role of thermal stresses on pulsed laser irradiation of thin films under conditions of microbump formation and nonvaporization forward transfer

Science.gov (United States)

Meshcheryakov, Yuri P.; Shugaev, Maxim V.; Mattle, Thomas; Lippert, Thomas; Bulgakova, Nadezhda M.

2013-11-01

This paper presents a theoretical analysis of the processes in thin solid films irradiated by short and ultrashort laser pulses in the regimes of film structuring and laser-induced forward transfer. The regimes are considered at which vaporization of the film materials is insignificant and film dynamics is governed mainly by mechanical processes. Thermoelastoplastic modeling has been performed for a model film in one- and two-dimensional geometries. A method has been proposed to estimate the height of microbumps produced by nanosecond laser irradiation of solid films. Contrary to femtosecond laser pulses, in nanosecond pulse regimes, stress waves across the film are weak and cannot induce film damage. The main role in laser-induced dynamics of irradiated films is played by radial thermal stresses which lead to the formation of a bending wave propagating along the film and drawing the film matter to the center of the irradiation spot. The bending wave dynamics depends on the hardness of the substrate underlying the film. The causes of the receiver substrate damage sometimes observed upon laser-induced forward transfer in the scheme of the direct contact between the film and the receiver are discussed.

Determination of the optimum temperature history of inlet water for minimizing thermal stresses in a pipe by the multiphysics inverse analysis

International Nuclear Information System (INIS)

Kubo, S; Uchida, K; Ishizaka, T; Ioka, S

2008-01-01

It is important to reduce the thermal stresses for managing and extending the lives of pipes in plants. In this problem, heat conduction, elastic deformation, heat transfer, liquid flow should be considered, and therefore the problem is of a multidisciplinary nature. An inverse method was proposed by the present authors for determining the optimum thermal load history which reduced transient thermal stress considering the multidisciplinary physics. But the obtained solution had a problem that the temperature increasing rate of inner surface of the pipe was discontinuous at the end time of heat up. In this study we introduce temperature history functions that ensure the continuity of the temperature increasing rate. The multidisciplinary complex problem is decomposed into a heat conduction problem, a heat transfer problem, and a thermal stress problem. An analytical solution of the temperature distribution of radial thickness and thermal hoop stress distribution is obtained. The maximum tensile and compressive hoop stresses are minimized for the case where inner surface temperature T s (t) is expressed in terms of the 4th order polynomial function of time t. Finally, from the temperature distributions, the optimum fluid temperature history is obtained for reducing the thermal stresses.

Capillary-Condenser-Pumped Heat-Transfer Loop

Science.gov (United States)

Silverstein, Calvin C.

1989-01-01

Heat being transferred supplies operating power. Capillary-condenser-pumped heat-transfer loop similar to heat pipe and to capillary-evaporator-pumped heat-transfer loop in that heat-transfer fluid pumped by evaporation and condensation of fluid at heat source and sink, respectively. Capillary condenser pump combined with capillary evaporator pump to form heat exchanger circulating heat-transfer fluids in both loops. Transport of heat more nearly isothermal. Thermal stress in loop reduced, and less external surface area needed in condenser section for rejection of heat to heat sink.

Transfer function design based on user selected samples for intuitive multivariate volume exploration

KAUST Repository

Zhou, Liang

2013-02-01

Multivariate volumetric datasets are important to both science and medicine. We propose a transfer function (TF) design approach based on user selected samples in the spatial domain to make multivariate volumetric data visualization more accessible for domain users. Specifically, the user starts the visualization by probing features of interest on slices and the data values are instantly queried by user selection. The queried sample values are then used to automatically and robustly generate high dimensional transfer functions (HDTFs) via kernel density estimation (KDE). Alternatively, 2D Gaussian TFs can be automatically generated in the dimensionality reduced space using these samples. With the extracted features rendered in the volume rendering view, the user can further refine these features using segmentation brushes. Interactivity is achieved in our system and different views are tightly linked. Use cases show that our system has been successfully applied for simulation and complicated seismic data sets. © 2013 IEEE.

Transfer function design based on user selected samples for intuitive multivariate volume exploration

KAUST Repository

Zhou, Liang; Hansen, Charles

2013-01-01

Multivariate volumetric datasets are important to both science and medicine. We propose a transfer function (TF) design approach based on user selected samples in the spatial domain to make multivariate volumetric data visualization more accessible for domain users. Specifically, the user starts the visualization by probing features of interest on slices and the data values are instantly queried by user selection. The queried sample values are then used to automatically and robustly generate high dimensional transfer functions (HDTFs) via kernel density estimation (KDE). Alternatively, 2D Gaussian TFs can be automatically generated in the dimensionality reduced space using these samples. With the extracted features rendered in the volume rendering view, the user can further refine these features using segmentation brushes. Interactivity is achieved in our system and different views are tightly linked. Use cases show that our system has been successfully applied for simulation and complicated seismic data sets. © 2013 IEEE.

Elastic Stress Analysis of Rotating Functionally Graded Annular Disk of Variable Thickness Using Finite Difference Method

Directory of Open Access Journals (Sweden)

Mohammad Hadi Jalali

2018-01-01

Full Text Available Elastic stress analysis of rotating variable thickness annular disk made of functionally graded material (FGM is presented. Elasticity modulus, density, and thickness of the disk are assumed to vary radially according to a power-law function. Radial stress, circumferential stress, and radial deformation of the rotating FG annular disk of variable thickness with clamped-clamped (C-C, clamped-free (C-F, and free-free (F-F boundary conditions are obtained using the numerical finite difference method, and the effects of the graded index, thickness variation, and rotating speed on the stresses and deformation are evaluated. It is shown that using FG material could decrease the value of radial stress and increase the radial displacement in a rotating thin disk. It is also demonstrated that increasing the rotating speed can strongly increase the stress in the FG annular disk.

Transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations

International Nuclear Information System (INIS)

Sugano, Y.

1980-01-01

The transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations on two edges are studied by means of the Airy stress function. The purposes of this paper are to present a method of determing the transient thermal stresses in an orthographic rectangular plate with four edges of distinct thermal boundary condition of the third kind which exactly satisfy the traction-free conditions of shear stress over all boundaries including four corners of the plate, and to consider the effects of the anisotropies of material properties and the convective heat transfer on the upper and lower surfaces on the thermal stress distribution. (orig.)

Uncertainty of Monetary Valued Ecosystem Services – Value Transfer Functions for Global Mapping

Science.gov (United States)

Schmidt, Stefan; Manceur, Ameur M.; Seppelt, Ralf

2016-01-01

Growing demand of resources increases pressure on ecosystem services (ES) and biodiversity. Monetary valuation of ES is frequently seen as a decision-support tool by providing explicit values for unconsidered, non-market goods and services. Here we present global value transfer functions by using a meta-analytic framework for the synthesis of 194 case studies capturing 839 monetary values of ES. For 12 ES the variance of monetary values could be explained with a subset of 93 study- and site-specific variables by utilizing boosted regression trees. This provides the first global quantification of uncertainties and transferability of monetary valuations. Models explain from 18% (water provision) to 44% (food provision) of variance and provide statistically reliable extrapolations for 70% (water provision) to 91% (food provision) of the terrestrial earth surface. Although the application of different valuation methods is a source of uncertainty, we found evidence that assuming homogeneity of ecosystems is a major error in value transfer function models. Food provision is positively correlated with better life domains and variables indicating positive conditions for human well-being. Water provision and recreation service show that weak ownerships affect valuation of other common goods negatively (e.g. non-privately owned forests). Furthermore, we found support for the shifting baseline hypothesis in valuing climate regulation. Ecological conditions and societal vulnerability determine valuation of extreme event prevention. Valuation of habitat services is negatively correlated with indicators characterizing less favorable areas. Our analysis represents a stepping stone to establish a standardized integration of and reporting on uncertainties for reliable and valid benefit transfer as an important component for decision support. PMID:26938447

Homologous recombination mediates functional recovery of dysferlin deficiency following AAV5 gene transfer.

Directory of Open Access Journals (Sweden)

William E Grose

Full Text Available The dysferlinopathies comprise a group of untreatable muscle disorders including limb girdle muscular dystrophy type 2B, Miyoshi myopathy, distal anterior compartment syndrome, and rigid spine syndrome. As with other forms of muscular dystrophy, adeno-associated virus (AAV gene transfer is a particularly auspicious treatment strategy, however the size of the DYSF cDNA (6.5 kb negates packaging into traditional AAV serotypes known to express well in muscle (i.e. rAAV1, 2, 6, 8, 9. Potential advantages of a full cDNA versus a mini-gene include: maintaining structural-functional protein domains, evading protein misfolding, and avoiding novel epitopes that could be immunogenic. AAV5 has demonstrated unique plasticity with regards to packaging capacity and recombination of virions containing homologous regions of cDNA inserts has been implicated in the generation of full-length transcripts. Herein we show for the first time in vivo that homologous recombination following AAV5.DYSF gene transfer leads to the production of full length transcript and protein. Moreover, gene transfer of full-length dysferlin protein in dysferlin deficient mice resulted in expression levels sufficient to correct functional deficits in the diaphragm and importantly in skeletal muscle membrane repair. Intravascular regional gene transfer through the femoral artery produced high levels of transduction and enabled targeting of specific muscle groups affected by the dysferlinopathies setting the stage for potential translation to clinical trials. We provide proof of principle that AAV5 mediated delivery of dysferlin is a highly promising strategy for treatment of dysferlinopathies and has far-reaching implications for the therapeutic delivery of other large genes.

Time constants and feedback transfer functions of EBR-II subassembly types

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1986-01-01

Time constants, feedback reactivity transfer functions and power coefficients are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a reactor kinetic code analysis for a step change in power. Due to the multiplicity of eigenvalues, there are several time constants for each nodal position in a subassembly. Compared with these calculated values are analytically derived values for the initial node of a given channel

Time constants and feedback transfer functions of EBR-II subassembly types

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1987-01-01

Time constants, feedback reactivity transfer functions and power coefficients are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a reactor kinetic code analysis for a step change in power. Due to the multiplicity of eigenvalues, there are several time constants for each nodal position in a subassembly. Compared with these calculated values are analytically derived values for the initial node of a given channel. (author)

Differential changes of metabolic brain activity and interregional functional coupling in prefronto-limbic pathways during different stress conditions: Functional imaging in freely behaving rodent pups

Directory of Open Access Journals (Sweden)

Joerg eBock

2012-05-01

Full Text Available The trumpet-tailed rat or degu (Octodon degus is an established model to investigate the consequences of early stress on the development of emotional brain circuits and behaviour. The aim of this study was to identify brain circuits, that respond to different stress conditions and to test if acute stress alters functional coupling of brain activity among prefrontal and limbic regions. Using functional imaging (2-Fluoro-deoxyglucose method in 8 day old male degu pups the following stress conditions were compared: (A pups together with parents and siblings (control, (B separation of the litter from the parents, (C individual separation from parents and siblings, (D individual separation and presentation of maternal calls. Condition (B significantly downregulated brain activity in the prefrontal cortex, hippocampus, nucleus accumbens and sensory areas compared to controls. Activity decrease was even more pronounced during condition (C, where, in contrast to all other regions, activity in the PAG was increased. Interestingly, brain activity in stress-associated brain regions such as the amygdala and habenula was not affected. In condition (D maternal vocalizations reactivated brain activity in the cingulate and precentral medial cortex, nucleus accumbens and striatum and in sensory areas. In contrast, reduced activity was measured in the prelimbic and infralimbic cortex and in the hippocampus and amygdala. Correlation analysis revealed complex, region- and situation-specific changes of interregional functional coupling among prefrontal and limbic brain regions during stress exposure. We show here for the first time that early life stress results in a widespread reduction of brain activity in the infant brain and changes interregional functional coupling. Moreover, maternal vocalizations can partly buffer stress-induced decrease in brain activity in some regions and evoked very different functional coupling patterns compared to the three other

Altered functional connectivity to stressful stimuli in prenatally cocaine-exposed adolescents.

Science.gov (United States)

Zakiniaeiz, Yasmin; Yip, Sarah W; Balodis, Iris M; Lacadie, Cheryl M; Scheinost, Dustin; Constable, R Todd; Mayes, Linda C; Sinha, Rajita; Potenza, Marc N

2017-11-01

Prenatal cocaine exposure (PCE) is linked to addiction and obesity vulnerability. Neural responses to stressful and appetitive cues in adolescents with PCE versus those without have been differentially linked to substance-use initiation. However, no prior studies have assessed cue-reactivity responses among PCE adolescents using a connectivity-based approach. Twenty-two PCE and 22 non-prenatally drug-exposed (NDE) age-, sex-, IQ- and BMI-matched adolescents participated in individualized guided imagery with appetitive (favorite-food), stressful and neutral-relaxing cue scripts during functional magnetic resonance imaging. Subjective favorite-food craving scores were collected before and after script exposure. A data-driven voxel-wise intrinsic connectivity distribution analysis was used to identify between-group differences and examine relationships with craving scores. A group-by-cue interaction effect identified a parietal lobe cluster where PCE versus NDE adolescents showed less connectivity during stressful and more connectivity during neutral-relaxing conditions. Follow-up seed-based connectivity analyses revealed that, among PCE adolescents, the parietal seed was positively connected to inferior parietal and sensory areas and negatively connected to corticolimbic during both stress and neutral-relaxing conditions. For NDE, greater parietal connectivity to parietal, cingulate and sensory areas and lesser parietal connectivity to medial prefrontal areas were found during stress compared to neutral-relaxing cueing. Craving scores inversely correlated with corticolimbic connectivity in PCE, but not NDE adolescents, during the favorite-food condition. Findings from this first data-driven intrinsic connectivity analysis of PCE influences on adolescent brain function indicate differences relating to PCE status and craving. These findings provide insight into the developmental impact of in utero drug exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

A study on fatigue crack growth behavior subjected to a single tensile overload: Part II. Transfer of stress concentration and its role in overload-induced transient crack growth

International Nuclear Information System (INIS)

Lee, S.Y.; Choo, H.; Liaw, P.K.; An, K.; Hubbard, C.R.

2011-01-01

The combined effects of overload-induced enlarged compressive residual stresses and crack tip blunting with secondary cracks are suggested to be responsible for the observed changes in the crack opening load and resultant post-overload transient crack growth behavior [Lee SY, Liaw PK, Choo H, Rogge RB, Acta Mater 2010;59:485-94]. In this article, in situ neutron diffraction experiments were performed to quantify the influence of the combined effects by investigating the internal-stress evolution at various locations away from the crack tip. In the overload-retardation period, stress concentration occurs in the crack blunting region (an overload point) until a maximum crack arrest load is reached. The stress concentration is then transferred from the blunting region to the propagating crack tip (following the overload), requiring a higher applied load, as the closed crack is gradually opened. The transfer phenomena of the stress concentration associated with a crack opening process account for the nonlinearity of strain response in the vicinity of the crack tip. The delaying action of stress concentration at the crack tip is understood in conjunction with the concept of a critical stress (i.e. the stress required to open the closed crack behind the crack tip). A linear relationship between Δε eff and ΔK eff provides experimental support for the hypothesis that ΔK eff can be considered as the fatigue crack tip driving force.