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Sample records for ii transient response

  1. Model refinement using transient response

    SciTech Connect

    Dohrmann, C.R.; Carne, T.G.

    1997-12-01

    A method is presented for estimating uncertain or unknown parameters in a mathematical model using measurements of transient response. The method is based on a least squares formulation in which the differences between the model and test-based responses are minimized. An application of the method is presented for a nonlinear structural dynamic system. The method is also applied to a model of the Department of Energy armored tractor trailer. For the subject problem, the transient response was generated by driving the vehicle over a bump of prescribed shape and size. Results from the analysis and inspection of the test data revealed that a linear model of the vehicle`s suspension is not adequate to accurately predict the response caused by the bump.

  2. DARHT-II Injector Transients and the Ferrite Damper

    SciTech Connect

    Waldron, Will; Reginato, Lou; Chow, Ken; Houck, Tim; Henestroza, Enrique; Yu, Simon; Kang, Michael; Briggs, Richard

    2006-08-04

    This report summarizes the transient response of the DARHT-II Injector and the design of the ferrite damper. Initial commissioning of the injector revealed a rise time excited 7.8 MHz oscillation on the diode voltage and stalk current leading to a 7.8 MHz modulation of the beam current, position, and energy. Commissioning also revealed that the use of the crowbar to decrease the voltage fall time excited a spectrum of radio frequency modes which caused concern that there might be significant transient RF electric field stresses imposed on the high voltage column insulators. Based on the experience of damping the induction cell RF modes with ferrite, the concept of a ferrite damper was developed to address the crowbar-excited oscillations as well as the rise-time-excited 7.8 MHz oscillations. After the Project decided to discontinue the use of the crowbar, further development of the concept focused exclusively on damping the oscillations excited by the rise time. The design was completed and the ferrite damper was installed in the DARHT-II Injector in February 2006. The organization of this report is as follows. The suite of injector diagnostics are described in Section 2. The data and modeling of the injector transients excited on the rise-time and also by the crowbar are discussed in Section 3; the objective is a concise summary of the present state of understanding. The design of the ferrite damper, and the small scale circuit simulations used to evaluate the ferrite material options and select the key design parameters like the cross sectional area and the optimum gap width, are presented in Section 4. The details of the mechanical design and the installation of the ferrite damper are covered in Section 5. A brief summary of the performance of the ferrite damper following its installation in the injector is presented in Section 6.

  3. Heat pipe transient response approximation.

    SciTech Connect

    Reid, R. S.

    2001-01-01

    A simple and concise routine that approximates the response of an alkali metal heat pipe to changes in evaporator heat transfer rate is described. This analytically based routine is compared with data from a cylindrical heat pipe with a crescent-annular wick that undergoes gradual (quasi-steady) transitions through the viscous and condenser boundary heat transfer limits. The sonic heat transfer limit can also be incorporated into this routine for heat pipes with more closely coupled condensers. The advantages and obvious limitations of this approach are discussed. For reference, a source code listing for the approximation appears at the end of this paper.

  4. Transient Response of FGM Pressure Vessels

    NASA Astrophysics Data System (ADS)

    Pekel, Hakan; Keles, Ibrahim; Temel, Beytullah; Tutuncu, Naki

    The present study aims to investigate the transient behavior of thick-walled cylinders under dynamic internal pressure. Analytical solutions are possible only for simple time-dependent pressure functions. The solution procedure presented is general in the sense that the pressure applied may be an arbitrary continuous function of time, impulsive or given in a discrete form. The material considered is isotropic and heterogeneous with properties varying in the radial direction termed as Functionally Graded Material (FGM). Laplace transform method is used and the inversion into the time domain is performed using the modified Durbin's method. Verification of the numerical procedure is performed by comparing the results with those of an analytical solution available in the literature for a simple exponentially-varying pressure. The inhomogeneity constant in the material property model is shown to have a significant effect on the transient response.

  5. The Transient Response of Cooling Ponds

    NASA Astrophysics Data System (ADS)

    Adams, E. Eric

    1982-10-01

    Cooling ponds are a form of closed cycle cooling used for steam-electric power plants. Because of their thermal inertia they provide an advantage over cooling towers in filtering fluctuations in intake temperature, which results in improved plant efficiency. By using linear systems theory, the transient behavior of various types of ponds is analyzed in response to periodic meteorological conditions (characterized by equilibrium temperature) and plant operational conditions (characterized by condenser temperature rise). Frequency response is expressed in terms of dimensionless ratios involving frequency of input forcing, characteristic hydraulic residence and surface response times, and appropriate mixing parameters. Results are also interpreted with respect to physical design variables, such as pond area, depth, degree of stratification, intake submergence, discharge entrance mixing, condenser flow rate, and temperature rise.

  6. Cascade flutter analysis with transient response aerodynamics

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Mahajan, Aparajit J.; Keith, Theo G., Jr.; Stefko, George L.

    1991-01-01

    Two methods for calculating linear frequency domain aerodynamic coefficients from a time marching Full Potential cascade solver are developed and verified. In the first method, the Influence Coefficient, solutions to elemental problems are superposed to obtain the solutions for a cascade in which all blades are vibrating with a constant interblade phase angle. The elemental problem consists of a single blade in the cascade oscillating while the other blades remain stationary. In the second method, the Pulse Response, the response to the transient motion of a blade is used to calculate influence coefficients. This is done by calculating the Fourier Transforms of the blade motion and the response. Both methods are validated by comparison with the Harmonic Oscillation method and give accurate results. The aerodynamic coefficients obtained from these methods are used for frequency domain flutter calculations involving a typical section blade structural model. An eigenvalue problem is solved for each interblade phase angle mode and the eigenvalues are used to determine aeroelastic stability. Flutter calculations are performed for two examples over a range of subsonic Mach numbers.

  7. 40 CFR Appendix II to Part 1048 - Large Spark-ignition (SI) Composite Transient Cycle

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Large Spark-ignition (SI) Composite Transient Cycle II Appendix II to Part 1048 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY.... 1048, App. II Appendix II to Part 1048—Large Spark-ignition (SI) Composite Transient Cycle...

  8. Transient response of premixed methane flames

    SciTech Connect

    Vagelopoulos, Christina M.; Frank, Jonathan H.

    2006-08-15

    The response of premixed methane-air flames to transient strain and local variations in equivalence ratio is studied during isolated interactions between a line-vortex pair and a V-flame. The temporal evolution of OH and CH is measured with planar laser-induced fluorescence for N{sub 2}-diluted flames with equivalence ratios ranging from 0.8 to 1.2. One-dimensional laminar flame calculations are used to simulate the flame response to unsteady strain and variations in reactant composition. When the reactant composition of the vortex pair and the V-flame are identical, the measurements and predictions show that the peak mole fractions of OH and CH decay monotonically in lean, stoichiometric, and rich flames. We also investigate the effects of a vortex pair with a leaner composition than the V-flame. In a stoichiometric flame, the leaner vortex enhances the decay of both OH and CH. In a rich flame, we observe an abrupt increase in OH-LIF signal and a disappearance of CH-LIF signal that are consistent with a previous experimental investigation. Our results indicate that the previously observed OH burst and CH breakage were caused by a difference in the equivalence ratios of the vortex pair and the main reactant flow. A numerical study shows that N{sub 2} dilution enhances the response of premixed flames to unsteady strain and variations in stoichiometry. Reaction-path and sensitivity analyses indicate that the peak OH and CH mole fractions exhibit significant sensitivity to the main branching reaction, H+O{sub 2} {r_reversible}OH+O. The sensitivity of OH and CH to this and other reactions is enhanced by N{sub 2} dilution. As a result, N{sub 2}-diluted flames provide a good test case for studying the reliability of chemical kinetic and transport models. (author)

  9. Analysis of nonlinear transient responses of piezoelectric resonators.

    PubMed

    Hagiwara, Manabu; Takahashi, Seita; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki

    2011-09-01

    The electric transient response method is an effective technique to evaluate material constants of piezoelectric ceramics under high-power driving. In this study, we tried to incorporate nonlinear piezoelectric behaviors in the analysis of transient responses. As a base for handling the nonlinear piezoelectric responses, we proposed an assumption that the electric displacement is proportional to the strain without phase lag, which could be described by a real and constant piezoelectric e-coefficient. Piezoelectric constitutive equations including nonlinear responses were proposed to calculate transient responses of a piezoelectric resonator. The envelopes and waveforms of current and vibration velocity in transient responses observed in some piezoelectric ceramics could be fitted with the calculation including nonlinear responses. The procedure for calculation of mechanical quality factor Q(m) for piezoelectric resonators with nonlinear behaviors was also proposed.

  10. Transient response characteristics in a biomolecular integral controller.

    PubMed

    Sen, Shaunak

    2016-04-01

    The cellular behaviour of perfect adaptation is achieved through the use of an integral control element in the underlying biomolecular circuit. It is generally unclear how integral action affects the important aspect of transient response in these biomolecular systems, especially in light of the fact that it typically deteriorates the transient response in engineering contexts. To address this issue, the authors investigated the transient response in a computational model of a simple biomolecular integral control system involved in bacterial signalling. They find that the transient response can actually speed up as the integral gain parameter increases. On further analysis, they find that the underlying dynamics are composed of slow and fast modes and the speed-up of the transient response is because of the speed-up of the slow-mode dynamics. Finally, they note how an increase in the integral gain parameter also leads to a decrease in the amplitude of the transient response, consistent with the overall improvement in the transient response. These results should be useful in understanding the overall effect of integral action on system dynamics, particularly for biomolecular systems.

  11. Type II intermediate-luminosity optical transients (ILOTs)

    NASA Astrophysics Data System (ADS)

    Kashi, Amit; Soker, Noam

    2017-01-01

    We propose that in a small fraction of intermediate luminosity optical transients (ILOTs) powered by a strongly interacting binary system, the ejected mass in the equatorial plane can block the central source from our line of sight. We can therefore observe only radiation that is reprocessed by polar outflow, much as in type II active galactic nuclei (AGN). An ejection of M_ej,e=10^{-4} M_⊙ (1 M_⊙) at 30 degrees from the equatorial plane and at a velocity of v_e = 100 {km} {s}^{-1} will block the central source in the NIR for about 5 years (500 years). During that period of time the object might disappear in the visible band, and be detected only in the IR band due to polar dust. We raise the possibility that the recently observed disappearance of a red giant in the visible, designated N6946-BH1, is a type II ILOT rather than a failed supernova. For this case we estimate that the ejected mass in the polar direction was M_ej,p≈ 10^{-3} M_⊙. Our scenario predicts that this event should reinstate its visible emission in several decades.

  12. Transient response of a laminated composite plate

    NASA Technical Reports Server (NTRS)

    Datta, S. K.; Ju, T. H.; Bratton, R. L.; Shah, A. H.

    1992-01-01

    Results are presented from an investigation of the effect of layering on transient wave propagation in a laminated cross-ply plate, giving attention to the case of 2D plane strain in the case where a line vertical force is applied on a free surface of the plate; the line may be either parallel or perpendicular to the fibers in a ply. The results are in both the time and frequency domains for the normal stress component in the x direction, at a point on the surface of the plate on which the force is applied. Comparative results are also presented for a homogeneous plate whose properties are the static effective ones, when the number of plies is large.

  13. Transient response of sap flow to wind speed.

    PubMed

    Chu, Chia R; Hsieh, Cheng-I; Wu, Shen-Yuang; Phillips, Nathan G

    2009-01-01

    Transient responses of sap flow to step changes in wind speed were experimentally investigated in a wind tunnel. A Granier-type sap flow sensor was calibrated and tested in a cylindrical tube for analysis of its transient time response. Then the sensor was used to measure the transient response of a well-watered Pachira macrocarpa plant to wind speed variations. The transient response of sap flow was described using the resistance-capacitance model. The steady sap flow rate increased as the wind speed increased at low wind speeds. Once the wind speed exceeded 8.0 m s(-1), the steady sap flow rate did not increase further. The transpiration rate, measured gravimetrically, showed a similar trend. The response of nocturnal sap flow to wind speed variation was also measured and compared with the results in the daytime. Under the same wind speed, the steady sap flow rate was smaller than that in the daytime, indicating differences between diurnal and nocturnal hydraulic function, and incomplete stomatal closure at night. In addition, it was found that the temporal response of the Granier sensor is fast enough to resolve the transient behaviour of water flux in plant tissue.

  14. Transient pupil response is modulated by contrast-based saliency.

    PubMed

    Wang, Chin-An; Boehnke, Susan E; Itti, Laurent; Munoz, Douglas P

    2014-01-08

    The sudden appearance of a novel stimulus in the environment initiates a series of orienting responses that include coordinated shifts of gaze and attention, and also transient changes in pupil size. Although numerous studies have identified a significant effect of stimulus saliency on shifts of gaze and attention, saliency effects on pupil size are less understood. To examine salience-evoked pupil responses, we presented visual, auditory, or audiovisual stimuli while monkeys fixated a central visual spot. Transient pupil dilation was elicited after visual stimulus presentation regardless of target luminance relative to background, and auditory stimuli also evoked similar pupil responses. Importantly, the evoked pupil response was modulated by contrast-based saliency, with faster and larger pupil responses following the presentation of more salient stimuli. The initial transient component of pupil dilation was qualitatively similar to that evoked by weak microstimulation of the midbrain superior colliculus. The pupil responses elicited by audiovisual stimuli were well predicted by a linear summation of each modality response. Together, the results suggest that the transient pupil response, as one component of orienting, is modulated by contrast-based saliency, and the superior colliculus is likely involved in its coordination.

  15. Response of dairy cattle to transient voltages and magnetic fields

    SciTech Connect

    Reinemann, D.J.; Laughlin, N.K.; Stetson, L.E.

    1995-07-01

    Stray voltages in dairy facilities have been studied since the 1970`s. Previous research using steady-state ac and dc voltages has defined cow-contact voltage levels which may cause behavior and associated production problems. This research was designed to address concerns over possible effects of transient voltages and magnetic fields on dairy cows. Dairy cows response to transient voltages and magnetic fields was measured. The waveforms of the transient voltages applied were: 5 cycles of 60-Hz ac with a total pulse time of 83 ms, 1 cycle of 60-Hz ac with a total pulse time of 16 ms, and 1 cycle of an ac square wave (spiking positive and negative) of 2-ms duration. Alternating magnetic fields were produced by passing 60-Hz ac fundamental frequency with 2nd and 3rd harmonic and random noise components in metal structures around the cows. The maximum magnetic field associated with this current flow was in excess of 4 G. A wide range of sensitivity to transient voltages was observed among cows. Response levels from 24 cows to each transient exposure were normally distributed. No responses to magnetic fields were observed.

  16. Computing Response Of A Structure To Random Transient Pressures

    NASA Technical Reports Server (NTRS)

    Sepcenko, Valentin; Margasahayam, Ravi

    1994-01-01

    Improved method of computing vibrational response of structure to transient random acoustic excitation at predominantly low frequencies devised, called "deterministic". Motivated by need to analyze more accurately vibro/acoustic responses of structures at spacecraft-launching facilities and determine whether need for reinforcement or redesign to withstand launch environment. Also used to study such phenomena as earthquake motions, ocean waves, aircraft pressure gusts, responses of bridges to winds, and effects to jet-engine noise on aircraft structures.

  17. Transient Receptor Potential Melastatin 7 Cation Channel Kinase: New Player in Angiotensin II-Induced Hypertension.

    PubMed

    Antunes, Tayze T; Callera, Glaucia E; He, Ying; Yogi, Alvaro; Ryazanov, Alexey G; Ryazanova, Lillia V; Zhai, Alexander; Stewart, Duncan J; Shrier, Alvin; Touyz, Rhian M

    2016-04-01

    Transient receptor potential melastatin 7 (TRPM7) is a bifunctional protein comprising a magnesium (Mg(2+))/cation channel and a kinase domain. We previously demonstrated that vasoactive agents regulate vascular TRPM7. Whether TRPM7 plays a role in the pathophysiology of hypertension and associated cardiovascular dysfunction is unknown. We studied TRPM7 kinase-deficient mice (TRPM7Δkinase; heterozygous for TRPM7 kinase) and wild-type (WT) mice infused with angiotensin II (Ang II; 400 ng/kg per minute, 4 weeks). TRPM7 kinase expression was lower in heart and aorta from TRPM7Δkinase versus WT mice, effects that were further reduced by Ang II infusion. Plasma Mg(2+) was lower in TRPM7Δkinase versus WT mice in basal and stimulated conditions. Ang II increased blood pressure in both strains with exaggerated responses in TRPM7Δkinase versus WT groups (P<0.05). Acetylcholine-induced vasorelaxation was reduced in Ang II-infused TRPM7Δkinase mice, an effect associated with Akt and endothelial nitric oxide synthase downregulation. Vascular cell adhesion molecule-1 expression was increased in Ang II-infused TRPM7 kinase-deficient mice. TRPM7 kinase targets, calpain, and annexin-1, were activated by Ang II in WT but not in TRPM7Δkinase mice. Echocardiographic and histopathologic analysis demonstrated cardiac hypertrophy and left ventricular dysfunction in Ang II-treated groups. In TRPM7 kinase-deficient mice, Ang II-induced cardiac functional and structural effects were amplified compared with WT counterparts. Our data demonstrate that in TRPM7Δkinase mice, Ang II-induced hypertension is exaggerated, cardiac remodeling and left ventricular dysfunction are amplified, and endothelial function is impaired. These processes are associated with hypomagnesemia, blunted TRPM7 kinase expression/signaling, endothelial nitric oxide synthase downregulation, and proinflammatory vascular responses. Our findings identify TRPM7 kinase as a novel player in Ang II-induced hypertension

  18. Convergence of finite difference transient response computations for thin shells.

    NASA Technical Reports Server (NTRS)

    Sobel, L. H.; Geers, T. L.

    1973-01-01

    Numerical studies pertaining to the limits of applicability of the finite difference method in the solution of linear transient shell response problems are performed, and a computational procedure for the use of the method is recommended. It is found that the only inherent limitation of the finite difference method is its inability to reproduce accurately response discontinuities. This is not a serious limitation in view of natural constraints imposed by the extension of Saint Venant's principle to transient response problems. It is also found that the short wavelength limitations of thin shell (Bernoulli-Euler) theory create significant convergence difficulties in computed response to certain types of transverse excitations. These difficulties may be overcome, however, through proper selection of finite difference mesh dimensions and temporal smoothing of the excitation.

  19. Transient responses to spatial perturbations in advective systems.

    PubMed

    Anderson, Kurt E; Nisbet, Roger M; McCauley, Edward

    2008-07-01

    We study the transient dynamics, following a spatially-extended perturbation of models describing populations residing in advective media such as streams and rivers. Our analyses emphasize metrics that are independent of initial perturbations-resilience, reactivity, and the amplification envelope-and relate them to component spatial wavelengths of the perturbation using spatial Fourier transforms of the state variables. This approach offers a powerful way of understanding the influence of spatial scale on the initial dynamics of a population following a spatially variable environmental perturbation, an important property in determining the ecological implications of transient dynamics in advective systems. We find that asymptotically stable systems may exhibit transient amplification of perturbations (i.e., have positive reactivity) for some spatial wavelengths and not others. Furthermore, the degree and duration of amplification varies strongly with spatial wavelength. For two single-population models, there is a relationship between transient dynamics and the response length that characterizes the steady state response to spatial perturbations: a long response length implies that peak amplification of perturbations is small and occurs fast. This relationship holds less generally in a specialist consumer-resource model, likely due to the model's tendency for flow-induced instabilities at an alternative characteristic spatial scale.

  20. Analysis of piping response to thermal and operational transients

    SciTech Connect

    Wang, C.Y.

    1987-01-01

    The reactor piping system is an extremely complex three-dimensional structure. Maintaining its structural integrity is essential to the safe operation of the reactor and the steam-supply system. In the safety analysis, various transient loads can be imposed on the piping which may cause plastic deformation and possible damage to the system, including those generated from hydrodynamic wave propagations, thermal and operational transients, as well as the seismic events. At Argonne National Laboratory (ANL), a three-dimensional (3-D) piping code, SHAPS, aimed for short-duration transients due to wave propagation, has been developed. Since 1984, the development work has been shifted to the long-duration accidents originating from the thermal and operational transient. As a result, a new version of the code, SHAPS-2, is being established. This paper describes many features related to this later development. To analyze piping response generated from thermal and operational transients, a 3-D implicit finite element algorithm has been developed for calculating the hoop, flexural, axial, and torsional deformations induced by the thermomechanical loads. The analysis appropriately accounts for stresses arising from the temperature dependence of the elastic material properties, the thermal expansion of the materials, and the changes in the temperature-dependent yield surface. Thermal softening, failure, strain rate, creep, and stress ratching can also be considered.

  1. Reducing Conservatism of Analytic Transient Response Bounds via Shaping Filters

    NASA Technical Reports Server (NTRS)

    Kwan, Aiyueh; Bedrossian, Nazareth; Jan, Jiann-Woei; Grigoriadis, Karolos; Hua, Tuyen (Technical Monitor)

    1999-01-01

    Recent results show that the peak transient response of a linear system to bounded energy inputs can be computed using the energy-to-peak gain of the system. However, analytically computed peak response bound can be conservative for a class of class bounded energy signals, specifically pulse trains generated from jet firings encountered in space vehicles. In this paper, shaping filters are proposed as a Methodology to reduce the conservatism of peak response analytic bounds. This Methodology was applied to a realistic Space Station assembly operation subject to jet firings. The results indicate that shaping filters indeed reduce the predicted peak response bounds.

  2. Transient and sustained neural responses to death-related linguistic cues.

    PubMed

    Shi, Zhenhao; Han, Shihui

    2013-06-01

    Recent research showed that perception of death-related vs death-unrelated linguistic cues produced increased frontoparietal activity but decreased insular activity. This study investigated (i) whether the increased frontoparietal and decreased insular activities are, respectively, associated with transient trial-specific processes of death-related linguistic cues and sustained death-related thought during death-relevance judgments on linguistic cues and (ii) whether the neural activity underlying death-related thought can predict individuals' dispositional death anxiety. Participants were presented with death-related/unrelated words, life-related/unrelated words, and negative-valence/neutral words in separate sessions. Participants were scanned using functional magnetic resonance imaging while performing death-relevance, life-relevance, and valence judgments on the words, respectively. The contrast of death-related vs death-unrelated words during death-relevance judgments revealed transient increased activity in the left inferior parietal lobule, the right frontal eye field, and the right superior parietal lobule. The contrast of death-relevance judgments vs life-relevance/valence judgments showed decreased activity in the bilateral insula. The sustained insular activity was correlated with dispositional death anxiety, but only in those with weak transient frontoparietal responses to death-related words. Our results dissociate the transient and sustained neural responses to death-related linguistic cues and suggest that the combination of the transient and sustained neural activities can predict dispositional death anxiety.

  3. Response of traveling waves to transient inputs in neural fields.

    PubMed

    Kilpatrick, Zachary P; Ermentrout, Bard

    2012-02-01

    We analyze the effects of transient stimulation on traveling waves in neural field equations. Neural fields are modeled as integro-differential equations whose convolution term represents the synaptic connections of a spatially extended neuronal network. The adjoint of the linearized wave equation can be used to identify how a particular input will shift the location of a traveling wave. This wave response function is analogous to the phase response curve of limit cycle oscillators. For traveling fronts in an excitatory network, the sign of the shift depends solely on the sign of the transient input. A complementary estimate of the effective shift is derived using an equation for the time-dependent speed of the perturbed front. Traveling pulses are analyzed in an asymmetric lateral inhibitory network and they can be advanced or delayed, depending on the position of spatially localized transient inputs. We also develop bounds on the amplitude of transient input necessary to terminate traveling pulses, based on the global bifurcation structure of the neural field.

  4. Response of traveling waves to transient inputs in neural fields

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Zachary P.; Ermentrout, Bard

    2012-02-01

    We analyze the effects of transient stimulation on traveling waves in neural field equations. Neural fields are modeled as integro-differential equations whose convolution term represents the synaptic connections of a spatially extended neuronal network. The adjoint of the linearized wave equation can be used to identify how a particular input will shift the location of a traveling wave. This wave response function is analogous to the phase response curve of limit cycle oscillators. For traveling fronts in an excitatory network, the sign of the shift depends solely on the sign of the transient input. A complementary estimate of the effective shift is derived using an equation for the time-dependent speed of the perturbed front. Traveling pulses are analyzed in an asymmetric lateral inhibitory network and they can be advanced or delayed, depending on the position of spatially localized transient inputs. We also develop bounds on the amplitude of transient input necessary to terminate traveling pulses, based on the global bifurcation structure of the neural field.

  5. Transient hot-film sensor response in a shock tube

    NASA Technical Reports Server (NTRS)

    Roberts, A. S., Jr.; Ortgies, K. R.; Gartenberg, E.

    1989-01-01

    Shock tube experiments were performed to determine the response of a hot-film sensor, mounted flush on the side wall of a shock tube, to unsteady flow behind a normal shock wave. The present experiments attempt to isolate the response of the anemometer due only to the change in convective heat transfer at the hot-film surface. The experiments, performed at low supersonic shock speeds in air, are described along with the data acquisition procedure. The change in convective heat transfer is deduced from the data and the results are compared with those from transient boundary layer theory and another set of experimental results. Finally, a transient local heat transfer coefficient is formulated for use as the forcing function in a hot-film sensor instrument model simulation.

  6. Laboratory studies of spacecraft response to transient discharge pulses

    NASA Technical Reports Server (NTRS)

    Nanevicz, J. E.; Adamo, R. C.

    1985-01-01

    The in-orbit measurement of spacecraft discharge properties was investigated. The experiments include design and fabrication of appropriate sensors and effects of spacecraft electromagnetic responses on the interpretation of the discharge data. Electric field sensors especially designed to response to high-speed transient signals were installed on a mock-up of a satellite. The simple mock-up was basically a sheet of aluminum rolled to form a cylinder. A movable spark-discharge noise source designed to be electromagnetically isolated from its power supply system was used to induce transient signals at various locations on the spacecraft's outer surface. The measurements and their implications are described. It is concluded that practical orbital measurements to define discharge noise source properties should be possible, and that simple mock-ups of the type described below are useful in sensor system design and data interpretation.

  7. The transient thermal response of a tubular solar collector

    NASA Technical Reports Server (NTRS)

    Lansing, F. L.

    1976-01-01

    A special analytical solution is provided for the timewise response of the circulating fluid temperatures when a sudden step change of the input solar radiation is imposed and remains constant thereafter. An example which demonstrates the transient temperatures at the exit section of a single collector with two different flow patterns is presented. This study is used to supplement some numerical solutions to provide a fairly complete coverage for this type of solar collector.

  8. Transient photocyclization in ruthenium(ii) polypyridine complexes of indolamines.

    PubMed

    Carrone, G; Zayat, L; Slep, L D; Etchenique, R

    2017-01-18

    Ruthenium polypyridine complexes have proved to be useful caging groups for visible-light photodelivery of biomolecules. In most photoreactions, one ligand is expelled upon irradiation, yielding ruthenium mono-aqua complexes and no other photoproduct. In this work we show that a long-lived transient photoproduct is generated when the ruthenium complexes involve indolamines. The spatial conformation of this species is compatible with a cyclic structure that contains both the amine and the normally non-coordinating aromatic ring coordinated to the ruthenium center.

  9. Pupillary transient responses to within-task cognitive load variation.

    PubMed

    Wong, Hoe Kin; Epps, Julien

    2016-12-01

    Changes in physiological signals due to task evoked cognitive load have been reported extensively. However, pupil size based approaches for estimating cognitive load on a moment-to-moment basis are not as well understood as estimating cognitive load on a task-to-task basis, despite the appeal these approaches have for continuous load estimation. In particular, the pupillary transient response to instantaneous changes in induced load has not been experimentally quantified, and the within-task changes in pupil dilation have not been investigated in a manner that allows their consistency to be quantified with a view to biomedical system design. In this paper, a variation of the digit span task is developed which reliably induces rapid changes of cognitive load to generate task-evoked pupillary responses (TEPRs) associated with large, within-task load changes. Linear modelling and one-way ANOVA reveals that increasing the rate of cognitive loading, while keeping task demands constant, results in a steeper pupillary response. Instantaneous drops in cognitive load are shown to produce statistically significantly different transient pupillary responses relative to sustained load, and when characterised using an exponential decay response, the task-evoked pupillary response time constant is in the order of 1-5 s. Within-task test-retest analysis confirms the reliability of the moment-to-moment measurements. Based on these results, estimates of pupil diameter can be employed with considerably more confidence in moment-to-moment cognitive load estimation systems.

  10. Transient cardio-respiratory responses to visually induced tilt illusions

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Ramsdell, C. D.; Mullen, T. J.; Oman, C. M.; Harm, D. L.; Paloski, W. H.

    2000-01-01

    Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

  11. Transient response of a concentric evacuated tubular solar collector

    NASA Astrophysics Data System (ADS)

    Al-Khalil, Kamel M.; Jakubowski, Gerald S.; Springman, Richard A.

    The transient and the steady state performances of an evacuated coaxial tubular solar collector were investigated. A purely implicit central finite differencing numerical technique was used to determine the time-varying temperature distributions in the collector components as well as the fluid exit temperature. Experimental indoor transient tests were conducted in which step inputs of insolation were used. Close agreeement between the experimental and the theoretical results was obtained. The computer model was found to be useful to carry out a complete parametric study. The latter showed that the fluid flow rate had the largest effect on the performance of the collector tube. Lower flow rates resulted in lower efficiencies and longer response times.

  12. Transient thermal response of a hot-wire anemometer

    NASA Astrophysics Data System (ADS)

    Morris, S. C.; Foss, J. F.

    2003-03-01

    The ability of a thermal anemometry system to accurately measure unsteady fluid velocity depends on the electrical control system as well as the thermal properties of the sensor. The present work is a numerical study of the thermal transient response of a hot-wire. A conventional constant temperature anemometer with an ideal feedback amplifier as well as a pulse width modulated system were used to model the electrical current supplied to the sensor to maintain a nominally constant sensor resistance. The agreement between these two electrical models confirmed that the response characteristics are only due to thermal effects. The thermal response was tested by providing a known input function for the cooling velocity, and comparing this with the output of the model. The first test used a step input function. It was found that the thermal transient effects along the length of the sensor caused the system to initially under predict the actual velocity increase; this was followed by an exponential increase to the steady state velocity. Secondly, the model was tested with sinusoidal inputs over a wide frequency range. The ratio: indicated-velocity/input-velocity, as a function of the input frequency was used to characterize the 'thermal frequency response'.

  13. Vegetation Response to Transient Drought Events in the Upper Midwest

    NASA Astrophysics Data System (ADS)

    Minckley, T.; Booth, R.; Jackson, S.

    2006-12-01

    Two paleohydrological proxies from bog sediments, water level based on testate amoebae assemblages and peat humification, indicate both prolonged and transient drought events over the past 3500 years. High- resolution pollen data for the periods 3000-2200 and 1400-500 cal yr BP from Minden Bog (46.6106N, 82.8347W), Michigan were examined to assess how regional vegetation composition was affected by drought events. Between 3000-2200 cal yr BP, four intervals of multi-decadal drought and one prolonged drought episode were identified. Four of the five dominant arboreal pollen taxa (Betula, Fagus, Quercus and Pinus) do not appear to response to these particular events. In contrast, Tsuga percentages rise at the onset of a prolonged drought ca. 2850 cal yr BP, but decrease rapidly for the duration of this event. Between 1400-500 cal yr BP, five transient droughts and one prolonged dry period were identified. Betula, Pinus, and Tsuga generally increased and Fagus decreased during this period. These trends are punctuated by stepwise changes in pollen percentages associated with the onset and persistence of drought, particularly with the drought starting ca. 1000 cal yr BP. These data suggest that pollen-assemblage responses to climate variation occur across a broad range of scales, involving processes at landscape, community, population, and individual levels. At centennial timescales regional forest composition changes in response to climate variation via demographic processes and altered disturbance regimes. These responses can be rapid if the forcing is large enough. Transient drought events of lower magnitude (e.g., decadal/multidecadal) are accompanied by pollen responses, but these may be linked to changes in pollen productivity at the scale of individual trees across the landscape rather than demographic changes. Tree species differ in their physiological and reproductive responses to drought stress, with some reducing allocations to pollen productivity and others

  14. Phase-Amplitude Response Functions for Transient-State Stimuli

    PubMed Central

    2013-01-01

    Abstract The phase response curve (PRC) is a powerful tool to study the effect of a perturbation on the phase of an oscillator, assuming that all the dynamics can be explained by the phase variable. However, factors like the rate of convergence to the oscillator, strong forcing or high stimulation frequency may invalidate the above assumption and raise the question of how is the phase variation away from an attractor. The concept of isochrons turns out to be crucial to answer this question; from it, we have built up Phase Response Functions (PRF) and, in the present paper, we complete the extension of advancement functions to the transient states by defining the Amplitude Response Function (ARF) to control changes in the transversal variables. Based on the knowledge of both the PRF and the ARF, we study the case of a pulse-train stimulus, and compare the predictions given by the PRC-approach (a 1D map) to those given by the PRF-ARF-approach (a 2D map); we observe differences up to two orders of magnitude in favor of the 2D predictions, especially when the stimulation frequency is high or the strength of the stimulus is large. We also explore the role of hyperbolicity of the limit cycle as well as geometric aspects of the isochrons. Summing up, we aim at enlightening the contribution of transient effects in predicting the phase response and showing the limits of the phase reduction approach to prevent from falling into wrong predictions in synchronization problems. List of Abbreviations PRC phase response curve, phase resetting curve. PRF phase response function. ARF amplitude response function. PMID:23945295

  15. Curve fitting of aeroelastic transient response data with exponential functions

    NASA Technical Reports Server (NTRS)

    Bennett, R. M.; Desmarais, R. N.

    1976-01-01

    The extraction of frequency, damping, amplitude, and phase information from unforced transient response data is considered. These quantities are obtained from the parameters determined by fitting the digitized time-history data in a least-squares sense with complex exponential functions. The highlights of the method are described, and the results of several test cases are presented. The effects of noise are considered both by using analytical examples with random noise and by estimating the standard deviation of the parameters from maximum-likelihood theory.

  16. An Analysis of the Transient Responses of Acoustic Delay Lines

    NASA Astrophysics Data System (ADS)

    Okano, Tatsuo; Tominaga, Goroh

    1981-09-01

    Transient responses of acoustic delay lines (ADLs) were simulated on the assumptions that gas molecules in each segment of an ADL were in thermal equilibrium and that the straight-through component in the intruding gas was negligibly small. The flow rate of gas through an orifice was evaluated by using expressions of orifice conductance applicable in a wide pressure range. In order to examine the adequateness of the present method, the results of simulations were compared with several experimental data. The influence of the location of vacuum pumps and of arranging a high speed shutter at the entrance of an ADL were also simulated.

  17. Alkylation of terminal alkynes with transient σ-alkylpalladium(II) complexes: a carboalkynylation route to alkyl-substituted alkynes.

    PubMed

    Zhou, Ming-Bo; Huang, Xiao-Cheng; Liu, Yan-Yun; Song, Ren-Jie; Li, Jin-Heng

    2014-02-10

    A mild and general alkylation of terminal alkynes with transient σ-alkylpalladium(II) complexes for assembling alkyl-substituted alkynes is described. This method represents a new way to the use of transient σ-alkylpalladium(II) complexes in organic synthesis through 1,2-carboalkynylation of alkenes.

  18. Transient quantum coherent response to a partially coherent radiation field.

    PubMed

    Sadeq, Zaheen S; Brumer, Paul

    2014-02-21

    The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level V system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly different from traditional decoherence. These two excitation scenarios are also explored for a minimal "toy" model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.

  19. Transient quantum coherent response to a partially coherent radiation field

    SciTech Connect

    Sadeq, Zaheen S.; Brumer, Paul

    2014-02-21

    The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level V system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly different from traditional decoherence. These two excitation scenarios are also explored for a minimal “toy” model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.

  20. Transient heat transfer in helium II due to a sudden vacuum break

    NASA Astrophysics Data System (ADS)

    Bosque, Ernesto S.; Dhuley, Ram C.; Van Sciver, Steven W.

    2014-01-01

    To ensure future cryogenic devices meet safety and operational specifications, significant value is gained from a developed understanding of the transient heat fluxes that result from failure of an insulating vacuum jacket around a helium II (He II)-cooled device. A novel, one-dimensional experiment is successfully performed examining the phenomena immediately following a vacuum rupture onto a cryosurface. In the experiment, a fast-opening (˜10 ms) valve isolates a rigid container of ultra high purity nitrogen (N2) gas kept at room temperature and adjustable pressure from a vertically oriented, highly evacuated (˜10-3 Pa) tube roughly 1 m in length. The bottom of the evacuated tube is sealed via a 2.54 mm thick copper disk, whose bottom surface is in intimate contact with an open column of He II (˜1.8 K). The evacuated tube, disk, and He II column share a diameter of 24 mm. Opening the valve results in a vacuum rupture. N2 gas is immediately drawn into the evacuated space and cryopumped onto the disk as a growing layer of solid cryodeposit. Various coupled transient heat transfer processes proceed as the internal energy of the warm gas is transferred through the growing layer of solid N2, through the copper disk, and into the He II column. This work examines the qualitative nature of these transient phenomena and the magnitude of the heat fluxes present through each of the series of thermal resistances.

  1. Angular response calibration of the burst and transient source experiment

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1988-01-01

    The Gamma Ray Observatory includes four experiments designed to observe the gamma-ray universe. Laboratory measurements to test the response the Burst and Transient Source Experiment (BATSE) modules to gamma-ray sources that are non-axial were recently completed. The results of these observations are necessary for the correct interpretation of BATSE data obtained after it is put in Earth orbit. The launch is planned for March, 1900. Preliminary analyses of these test data show the presence of a radial dependence to the detector's light collection efficiency. It is proposed to evaluate the importance of this radial response, analyze future experimental data to derive the actual functional dependence on radius, and calculate the net effect on the output spectrum as a function of the angle of incidence.

  2. Evaluation of Stability and Transient Characteristics of ABWR-II Large Bundle Core and SSR Influence for Transient phenomena by TRACG Code

    SciTech Connect

    Masao, Chaki; Hideo, Soneda; Shinya, Mizokami; Hideya, Kitamura; Kouji, Hiraiwa; Takanori, Fukahori; Andersen, Jens G.

    2004-07-01

    The next generation ABWR, the ABWR-II, has been under development for more than a decade in Japan. Among various features newly adopted for the ABWR-II, a 1.5 times lager fuel bundle is notable. This bundle design makes it possible to increase the total number of fuel rods in the core while minimizing the reactor pressure vessel size increase. As a result, the void coefficient is more negative due to the harder neutron spectrum since a smaller hydrogen-to uranium (H/U) ratio with fuel inventory increase makes the neutron spectrum harder. This more negative void coefficient affects the stability and transient characteristics of the ABWR-II plant. We have evaluated the stability and transient characteristics by using analysis codes and proven that these characteristics do not affect the realization of the ABWR-II large bundle core concept. Furthermore, we have evaluated the influences for the stability and transient phenomena by using spectral shift rods (SSRs) for the ABWR-II core. The analytical results show that the use of SSRs increases the design margin for the core stability. Regarding transient phenomena, the analyses by the TRACG code show that the influence of using SSRs is very small and do not affect the realization of the ABWR-II plant. In addition, the sensitivity analyses with the TRACG code show that design parameters of SSRs, inlet hole diameter of ascending path etc, are not very sensitive for the transient phenomena. (authors)

  3. A look at Francis runner blades response during transients

    NASA Astrophysics Data System (ADS)

    Gagnon, M.; Nicolle, J.; Morissette, J.-F.; Lawrence, M.

    2016-11-01

    Data shows that the mechanical response of Francis runner blades is sensitive to power plant control systems. To demonstrate this, we have explored two such systems: wicket gates opening and air admission. The proper control of these systems does more than warrant safe operation; they can also be used to minimize the strain cycle amplitudes during transients such as: startups, shutdowns and load rejections. Proper control parameters settings should minimize the equipment risk of fatigue failure without negative side effects on other components and objectives. With the help of measured examples from Hydro-Québec power plants, this paper demonstrates that a better understanding of these systems is needed in order to move beyond costly trial and error fine-tuning methodology.

  4. Transient response of Salix cuttings to changing water level regimes

    NASA Astrophysics Data System (ADS)

    Gorla, L.; Signarbieux, C.; Turberg, P.; Buttler, A.; Perona, P.

    2015-03-01

    Sustainable water management requires an understanding of the effects of flow regulation on riparian ecomorphological processes. We investigated the transient response of Salix viminalis by examining the effect of water-level regimes on its above-ground and below-ground biomass. Four sets of Salix cuttings, three juveniles (in the first growing season) and one mature (1 year old), were planted and initially grown under the same water-level regime for 1 month. We imposed three different water-level regime treatments representing natural variability, a seasonal trend with no peaks, and minimal flow (characteristic of hydropower) consisting of a constant water level and natural flood peaks. We measured sap flux, stem water potential, photosynthesis, growth parameters, and final root architecture. The mature cuttings were not affected by water table dynamics, but the juveniles displayed causal relationships between the changing water regime, plant growth, and root distribution during a 2 month transient period. For example, a 50% drop in mean sap flux corresponded with a -1.5 Mpa decrease in leaf water potential during the first day after the water regime was changed. In agreement with published field observations, the cuttings concentrated their roots close to the mean water table of the corresponding treatment, allowing survival under altered conditions and resilience to successive stress events. Juvenile development was strongly impacted by the minimum flow regime, leading to more than 60% reduction of both above-ground and below-ground biomass, with respect to the other treatments. Hence, we suggest avoiding minimum flow regimes where Salix restoration is prioritized.

  5. Radial response of the burst and transient source experiment

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1989-01-01

    The Gamma Ray Observatory (GRO) includes four experiments designed for observe the gamma-ray universe, one of which is the Burst And Transient Source Experiment (BATSE). During the first summer with the BATSE team in 1988, laboratory measurements were completed which test the response of the BATSE modules to gamma-ray sources that are non-axial. The results of these observations are necessary for the correct interpretation of BATSE data obtained after it is put in earth orbit. Subsequent analysis of the data revealed a shift in the centroids of the full-energy photopeaks for angles of incidence between about 70 and 110 degrees. This effect was diagnosed as being due to a radial dependence of the light collecting efficiency of the large-area detector (LAD). Energy-depositing events that occur near the perimeter of the 10-inch radius NaI disc are not as efficiently collected as those events that occur near the disc's center. This radial response is analyzed and in so doing the non-Gaussian shape of the photopeaks seen in the spectra taken at all angles is explained.

  6. Validation of the transient Structural Response of a Threaded Assembly

    SciTech Connect

    Doebling, S. W.; Hemez, F. M.; Schultze, J. F.

    2002-01-01

    This paper will demonstrate the application of model validation techniques to a transient structural dynamics problem. The problem of interest is the propagation of an explosive shock through a complex threaded joint that is a surrogate model of a system assembly. The objective is to validate the computational modeling of the key mechanical phenomena in the assembly, so that the component can be represented with adequate fidelity in the system-level model. A set of experiments was conducted on the threaded assembly where the acceleration and strain responses to an explosive load were measured on mass-simulators representing payloads. A significantly detailed computational model of the threaded assembly was also created. Numerical features that represent the important characteristics of the response were defined and calculated for both the experimental and computational data. Each step of the model validation process will be described as applied to this problem. Fundamental issues regarding the nature of model validation and the role of model validation in the engineering analysis process will also be discussed.

  7. Unstable transient response of gyroscopic systems with stable eigenvalues

    NASA Astrophysics Data System (ADS)

    Giannini, O.

    2016-06-01

    Gyroscopic conservative dynamical systems may exhibit flutter instability that leads to a pair of complex conjugate eigenvalues, one of which has a positive real part and thus leads to a divergent free response of the system. When dealing with non-conservative systems, the pitch fork bifurcation shifts toward the negative real part of the root locus, presenting a pair of eigenvalues with equal imaginary parts, while the real parts may or may not be negative. Several works study the stability of these systems for relevant engineering applications such as the flutter in airplane wings or suspended bridges, brake squeal, etc. and a common approach to detect the stability is the complex eigenvalue analysis that considers systems with all negative real part eigenvalues as stable systems. This paper studies analytically and numerically the cases where the free response of these systems exhibits a transient divergent time history even if all the eigenvalues have negative real part thus usually considered as stable, and relates such a behaviour to the non orthogonality of the eigenvectors. Finally, a numerical method to evaluate the presence of such instability is proposed.

  8. Spinal mechanisms underlying potentiation of hindpaw responses observed after transient hindpaw ischemia in mice

    PubMed Central

    Watanabe, Tatsunori; Sasaki, Mika; Komagata, Seiji; Tsukano, Hiroaki; Hishida, Ryuichi; Kohno, Tatsuro; Baba, Hiroshi; Shibuki, Katsuei

    2015-01-01

    Transient ischemia produces postischemic tingling sensation. Ischemia also produces nerve conduction block that may modulate spinal neural circuits. In the present study, reduced mechanical thresholds for hindpaw-withdrawal reflex were found in mice after transient hindpaw ischemia, which was produced by a high pressure applied around the hindpaw for 30 min. The reduction in the threshold was blocked by spinal application of LY354740, a specific agonist of group II metabotropic glutamate receptors. Neural activities in the spinal cord and the primary somatosensory cortex (S1) were investigated using activity-dependent changes in endogenous fluorescence derived from mitochondrial flavoproteins. Ischemic treatment induced potentiation of the ipsilateral spinal and contralateral S1 responses to hindpaw stimulation. Both types of potentiation were blocked by spinal application of LY354740. The contralateral S1 responses, abolished by lesioning the ipsilateral dorsal column, reappeared after ischemic treatment, indicating that postischemic tingling sensation reflects a sensory modality shift from tactile sensation to nociception in the spinal cord. Changes in neural responses were investigated during ischemic treatment in the contralateral spinal cord and the ipsilateral S1. Potentiation already appeared during ischemic treatment for 30 min. The present findings suggest that the postischemic potentiation shares spinal mechanisms, at least in part, with neuropathic pain. PMID:26165560

  9. Type II collagen is transiently expressed during avian cardiac valve morphogenesis.

    PubMed

    Swiderski, R E; Daniels, K J; Jensen, K L; Solursh, M

    1994-08-01

    We present new evidence of the temporal and spatial expression of type II collagen in the embryonic chick heart during the very early stages of its development. In particular, we emphasize the distribution of its mRNA and protein during valve formation. Type II collagen as well as several other fibrillar collagens (types I, III, and V) are present in stage 18 endocardial cushion mesenchymal cells. At stage 23, alpha 1 (II) collagen transcripts and the cognate polypeptide colocalize in the atrioventricular valves. As development proceeds, the relative abundance of alpha 1 (II) collagen transcripts decreases during the stages studied (stages 22 to 45; day 3.5 to day 19) as assayed by RNA blotting of extracts of whole hearts. Type II collagen protein was immunologically undetectable in stage 38 (day 12) hearts, although collagens I, III, and V persisted and localize in the valve regions, in the endothelial lining of the heart, and in the epicardium. In keeping with other observations of type II collagen expression in non-chondrogenic regions of a variety of vertebrate embryos, the avian heart also exhibits transient type II collagen expression.

  10. The human ventilatory response to stimulation by transient hypoxia.

    PubMed Central

    Jennett, S; McKay, F C; Moss, V A

    1981-01-01

    1. The detailed pattern of transient changes in breathing pattern has been studied following a brief hypoxic stimulus (three breaths of nitrogen) in nine healthy subjects. All showed an increase in ventilation of which the magnitude and relative contributions of volume and frequency varied between subjects. 2. Ventilation, tidal volume, inspiratory, expiratory and total breath time were recorded or derived breath-by-breath; for each of these variables, several test sequences were time-averaged at half-second intervals for each individual; similarly, time-averages were obtained for percentage changes from base line over all nine subjects. 3. There ws an increase in inspiratory time accompanying the increasing tidal volume, in all but two subjects. This was statistically significant over all subjects, and in five individuals. Frequency changes were the resultant of alterations in the two phases; when total breath duration decreased it was always linked to a decrease in expiratory time. 4. Further analysis of the initial part of the response suggests that an increase of the duration of an inspiration may be the first change allowing an increase in tidal volume, before the 'drive' increases; this may be a dynamic feature of the control system whatever the nature and site of action of the stimulus. PMID:7310713

  11. Analytical modeling for transient probe response in eddy current testing

    NASA Astrophysics Data System (ADS)

    Desjardins, Daniel

    Analytical models that describe the electromagnetic field interactions arising between field generating and sensing coils in close proximity to conducting structures can be used to enhance analysis and information extracted from signals obtained using electromagnetic non-destructive evaluation technologies. A novel strategy, which enables the derivation of exact solutions describing all electromagnetic interactions arising in inductively coupled circuits due to a voltage excitation, is developed in this work. Differential circuit equations are formulated in terms of an arbitrary voltage excitation and of the magnetic fields arising in inductive systems, using Faraday's law and convolution, and solved using the Fourier transform. The approach is valid for systems containing any number of driving and receiving coils, and include nearby conducting and ferromagnetic structures. In particular, the solutions account for feedback between a ferromagnetic conducting test piece and the driving and sensing coils, providing correct voltage response of the coils. Also arising from the theory are analytical expressions for complex inductances in a circuit, which account for real (inductive) and imaginary (loss) elements associated with conducting and ferromagnetic structures. A novel model-based method for simultaneous characterization of material parameters, which includes magnetic permeability, electrical conductivity, wall thickness and liftoff, is subsequently developed from the forward solutions. Furthermore, arbitrary excitation waveforms, such as a sinusoid or a square wave, for applications in conventional and transient eddy current, respectively, may be considered. Experimental results, obtained for a square wave excitation, are found to be in excellent agreement with the analytical predictions.

  12. Transient response of a thermal buffer: a study for ISABELLE

    SciTech Connect

    Schneider. W.J.

    1981-01-01

    Operation of the superconducting magnets in ISABELLE may necessitate rapid cooldown and warmup from ambient (300K) to liquid helium temperature (3K) to meet the requirements of the experimental program. Similarly, unprogrammed temperature excursions can also occur due to operator error or equipment malfunction. The coal bore tube of the magnets has a small mass relative to the more massive iron laminations and the stainless steel support tube. In addition the magnet coil, in thermal contact with the cold bore tube, has excellent heat transfer to the helium flowing through it compared to the iron mass. These two factors, mass and heat transfer, dictate that the cold bore tube will follow the temperature of the coolant more closely than the iron and hence substantial temperature gradients can exist. If the temperature difference between the coolant and the iron in the magnet exceeds 44K stress failure may occur to either the cold bore tube or the magnet dewar end cap. To preclude such failures from occuring at least two options are available. One method is to modify the magnet design by introducing flexibility between the bore tube and the end plate. Another is to introduce an insensitive thermal mass or buffer as has been suggested by Shutt, at the inlet of a sextant ahead of the first magnets. This paper describes the latter method, the design and transient response of a buffer during cooldown.

  13. Sensor Webs: Autonomous Rapid Response to Monitor Transient Science Events

    NASA Technical Reports Server (NTRS)

    Mandl, Dan; Grosvenor, Sandra; Frye, Stu; Sherwood, Robert; Chien, Steve; Davies, Ashley; Cichy, Ben; Ingram, Mary Ann; Langley, John; Miranda, Felix

    2005-01-01

    To better understand how physical phenomena, such as volcanic eruptions, evolve over time, multiple sensor observations over the duration of the event are required. Using sensor web approaches that integrate original detections by in-situ sensors and global-coverage, lower-resolution, on-orbit assets with automated rapid response observations from high resolution sensors, more observations of significant events can be made with increased temporal, spatial, and spectral resolution. This paper describes experiments using Earth Observing 1 (EO-1) along with other space and ground assets to implement progressive mission autonomy to identify, locate and image with high resolution instruments phenomena such as wildfires, volcanoes, floods and ice breakup. The software that plans, schedules and controls the various satellite assets are used to form ad hoc constellations which enable collaborative autonomous image collections triggered by transient phenomena. This software is both flight and ground based and works in concert to run all of the required assets cohesively and includes software that is model-based, artificial intelligence software.

  14. Transient elastic impact response of slender graphite rods

    SciTech Connect

    Erdem, I.

    2007-12-15

    Graphite rods are manufactured by extruding the mixture of calcined petroleum coke and coal tar pitch into the desired shape and baking the cooled specimens at about 800{sup o}C. Cracking can occur in rods during the manufacturing process. It is useful to be able to detect the presence of such cracks in the rods prior to their being machined and put into use as electrodes or cathodes or thermal insulator. In an effort to develop a nondestructive testing approach to evaluation of the rods, transient elastic impact was determined for slender rods. Theory for solid, slender rods provided an important starting point for this work. Subsequently, numerical models were developed and simulation was used to determine the response of rods containing cracks. Experiments on graphite rods with and without cracks were conducted and the internal condition determined from the recorded signals. The rods were then cut lengthwise to reveal the internal condition and verify the predicted results. In all cases the knowledge gained from simulation allowed for the presence of cracks to be detected.

  15. A theory of post-stall transients in axial compression systems. II - Application

    NASA Technical Reports Server (NTRS)

    Greitzer, E. M.; Moore, F. K.

    1985-01-01

    Using the theory developed in Part I, calculations have been carried out to show the evolution of the mass flow, pressure rise, and rotating-stall cell amplitude during compression system post-stall transients. In particular, it is shown that the unsteady growth or decay of the stall cell can have a significant effect on the instantaneous compressor pumping characteristic and hence on the overall system behavior. A limited parametric study is carried out to illustrate the impact of different system features on transient behavior. It is shown, for example, that the ultimate mode of system response, surge or stable rotating stall, depends not only on the B parameter, but also on the compressor length-to-radius ratio. Small values of this latter quantity tend to favor the occurrence of surge, as do large values of B. Based on the analytical and numerical results, several specific topics are suggested for future research on post-stall transients.

  16. Transient response for interaction of two dynamic bodies

    NASA Technical Reports Server (NTRS)

    Prabhakar, A.; Palermo, L. G.

    1987-01-01

    During the launch sequence of any space vehicle complicated boundary interactions occur between the vehicle and the launch stand. At the start of the sequence large forces exist between the two; contact is then broken in a short but finite time which depends on the release mechanism. The resulting vehicle response produces loads which are very high and often form the design case. It is known that the treatment of the launch pad as a second dynamic body is significant for an accurate prediction of launch response. A technique was developed for obtaining loads generated by the launch transient with the effect of pad dynamics included. The method solves uncoupled vehicle and pad equations of motion. The use of uncoupled models allows the simulation of vehicle launch in a single computer run. Modal formulation allows a closed-form solution to be written, eliminating any need for a numerical integration algorithm. When the vehicle is on the pad the uncoupled pad and vehicle equations have to be modified to account for the constraints they impose on each other. This necessitates the use of an iterative procedure to converge to a solution, using Lagrange multipliers to apply the required constraints. As the vehicle lifts off the pad the coupling between the vehicle and the pad is eliminated point by point until the vehicle flies free. Results obtained by this method were shown to be in good agreement with observed loads and other analysis methods. The resulting computer program is general, and was used without modification to solve a variety of contact problems.

  17. Transient CNS responses to repeated binge ethanol treatment

    PubMed Central

    Zahr, Natalie M; Rohlfing, Torsten; Mayer, Dirk; Luong, Richard; Sullivan, Edith V; Pfefferbaum, Adolf

    2016-01-01

    Adaptive changes occur in response to repeated exposure to drugs. Although ethanol (EtOH) is known to induce pharmacokinetic tolerance, the effects of EtOH on in vivo, magnetic resonance (MR)-detectable brain measures across repeated exposures have not previously been reported. Of 28 rats weighing 341±22g at baseline, 15 were assigned to the EtOH group and 13 to the control (Ctrl) group. EtOH animals were exposed to 5 cycles of 4-days of EtOH treatment followed by 10 days of recovery. Rats in both groups had structural MR imaging (MRI) scans and whole brain MR spectroscopy (MRS) at baseline, immediately following each binge period, and after each recovery period (total=11 MR scans per rat). Average blood alcohol levels (BALs) across each of the 5, 4-day binge periods were 298, 300, 301, 312, 318 mg/dL. Cerebrospinal fluid (CSF) volumes of the lateral ventricles and cisterns showed enlargement with each binge EtOH exposure but recovery with each abstinence period. Similarly, changes to MRS metabolites were transient: levels of N-acetyl aspartate (NAA) and total creatine (tCr) decreased, while those of choline-containing compounds (Cho) and glutamate/glutamine (Glx) increased with each binge EtOH exposure cycle, but also recovered during each abstinence period. The directionality of changes in response to EtOH were in expected directions based on previous, single-binge EtOH exposure experiments, but the current results do not provide support for accruing pathology with repeated binge EtOH exposure. PMID:26283309

  18. Effects of Activation Energy to Transient Response of Semiconductor Gas Sensor

    NASA Astrophysics Data System (ADS)

    Fujimoto, Akira; Ohtani, Tatsuki

    The smell classifiable gas sensor will be desired for many applications such as gas detection alarms, process controls for food production and so on. We have tried to realize the sensor using transient responses of semiconductor gas sensor consisting of tin dioxide and pointed out that the sensor gave us different transient responses for kinds of gas. Results of model calculation showed the activation energy of chemical reaction on the sensor surface strongly depended on the transient response. We tried to estimate the activation energies by molecular orbital calculation with SnO2 Cluster. The results show that there is a liner relationship between the gradient of the transient responses and activation energies for carboxylic and alcoholic gases. Transient response will be predicted from activation energy in the same kind of gas and the smell discrimination by single semiconductor gas sensor will be realized by this relationship.

  19. Transient river response, captured by channel steepness and its concavity

    NASA Astrophysics Data System (ADS)

    Vanacker, Veerle; von Blanckenburg, Friedhelm; Govers, Gerard; Molina, Armando; Campforts, Benjamin; Kubik, Peter W.

    2015-01-01

    Mountain rivers draining tropical regions are known to be great conveyor belts carrying efficiently more than half of the global sediment flux to the oceans. Many tropical mountain areas are located in tectonically active belts where the hillslope and stream channel morphology are rapidly evolving in response to changes in base level. Here, we report basin-wide denudation rates for an east-west transect through the tropical Andes. Hillslope and channel morphology vary systematically from east to west, reflecting the transition from high relief, strongly dissected topography in the escarpment zones into relatively low relief topography in the inter-Andean valley. The spatial pattern of differential denudation rates reflects the transient adjustment of the landscape to rapid river incision following tectonic uplift and river diversion. In the inter-Andean valley, upstream of the wave of incision, slopes and river channels display a relatively smooth, concave-up morphology and denudation rates (time scale of 104-105 a) are consistently low (3 to 200 mm/ka). In contrast, slopes and river channels of rejuvenated basins draining the eastern cordillera are steep to very steep; and the studied drainage basins show a wide range of denudation rate values (60 to 400 mm/ka) that increase systematically with increasing basin mean slope gradient, channel steepness, and channel convexity. Drainage basins that are characterised by strong convexities in their river longitudinal profiles systematically have higher denudation rates. As such, this is one of the first studies that provides field-based evidence of a correlation between channel concavity and basin mean denudation rates, consistent with process-based fluvial incision models.

  20. The unique sound of the uni-vibe pedal: Part II. Transient behaviour

    NASA Astrophysics Data System (ADS)

    Hahlweg, Cornelius F.; Rothe, Hendrik

    2013-09-01

    The Uni-Vibe is an effect pedal mostly used by electric guitar players. It is based on an opto-electronically controlled all-pass chain. In last year's paper on the subject an idealized system model was derived, which lead to deeper discussion of the musical consequences of the effect in terms of harmonic analysis of single tones and chords in clean and distorted mode. As a direct continuation the present paper deals with the transient behaviour of the device. The transient response is essential for understanding the special sound character, the reaction on picking techniques and the interaction with certain instruments. Therefore the system model is expanded and the pulse response of the idealized time invariant system is derived.

  1. Study on transient beam loading compensation for China ADS proton linac injector II

    NASA Astrophysics Data System (ADS)

    Gao, Zheng; He, Yuan; Wang, Xian-Wu; Chang, Wei; Zhang, Rui-Feng; Zhu, Zheng-Long; Zhang, Sheng-Hu; Chen, Qi; Powers, Tom

    2016-05-01

    Significant transient beam loading effects were observed during beam commissioning tests of prototype II of the injector for the accelerator driven sub-critical (ADS) system, which took place at the Institute of Modern Physics, Chinese Academy of Sciences, between October and December 2014. During these tests experiments were performed with continuous wave (CW) operation of the cavities with pulsed beam current, and the system was configured to make use of a prototype digital low level radio frequency (LLRF) controller. The system was originally operated in pulsed mode with a simple proportional plus integral and deviation (PID) feedback control algorithm, which was not able to maintain the desired gradient regulation during pulsed 10 mA beam operations. A unique simple transient beam loading compensation method which made use of a combination of proportional and integral (PI) feedback and feedforward control algorithm was implemented in order to significantly reduce the beam induced transient effect in the cavity gradients. The superconducting cavity field variation was reduced to less than 1.7% after turning on this control algorithm. The design and experimental results of this system are presented in this paper. Supported by National Natural Science Foundation of China (91426303, 11525523)

  2. Discovery of a transiently separable high-speed response component in cholesteric liquid crystals with a uniform lying helix

    NASA Astrophysics Data System (ADS)

    Inoue, Yo; Moritake, Hiroshi

    2015-06-01

    We report a novel high-speed response component observed in the transient state in cholesteric liquid crystals (ChLCs) with a uniform lying helix (ULH). When an electric field is applied normal to the helix axis, two well-known physical phenomena are induced: (i) the flexo-electric effect and (ii) the elongation of the helical structure. In this study, we show that the latter effect can be additionally separated into two different components with fast and slow response times, which reorient the LC director along the electric field without and with the helical pitch elongation, respectively.

  3. Charge recombination reactions in photosystem II. 2. Transient absorbance difference spectra and their temperature dependence.

    PubMed

    Hillmann, B; Brettel, K; van Mieghem, F; Kamlowski, A; Rutherford, A W; Schlodder, E

    1995-04-11

    Absorbance difference spectra of the transient states in photosystem II (PS II) have been examined in the Qv absorption region between 660 and 700 nm. The P680+Pheo-/P680Pheo, 3P680/P680, and P680+QA-/P680QA spectra were measured in O2-evolving PS II core complexes from Synechococcus and PS II-enriched membrane fragments from spinach. The low-temperature absorbance difference spectra vary only slightly between both PS II preparations. The 3P680/P680 spectrum is characterized by a bleaching at 685 nm at 25 K and indicates weak exciton coupling with neighboring pigment(s). We conclude that P680 absorbs at 685 nm in more intact PS II preparations at cryogenic temperature. The difference spectra of the radical pairs are strongly temperature dependent. At low temperature the P680+QA-/P680QA- spectrum exhibits the strongest bleaching at 675 nm whereas the P680+Phe-/P680Pheo spectra show two distinct bleaching bands at 674 and 684 nm. It is suggested that an electrochronic red shift resulting in a bleaching at 675 nm and an absorbance increase at about 682 nm dominates the spectral features of the charge-separated states. On the basis of the present results and those in the literature, we conclude that the interactions between the pigments and especially the organization of the primary donor must be quite different in PS II compared to bacterial reaction centers, although the basic structural arrangement of the pigments might be similar. Spectral data obtained with samples in the presence of singly and doubly reduced QA indicate that the primary photochemistry in PS II is not strongly influenced by the redox state of QA at low temperature and confirm the results of the accompanying paper [Van Mieghem, F. J. E., Brettel, K., Hillmann, B., Kamlowski, A., Rutherford, A. W., & Schlodder, E. (1995) Biochemistry 34, 4798-4813]. The spectra of the primary radical pair and the reaction center triplet obtained with more intact PS II preparations differ widely from those of D1/D2

  4. Long-rising Type II supernovae from Palomar Transient Factory and Caltech Core-Collapse Project

    NASA Astrophysics Data System (ADS)

    Taddia, F.; Sollerman, J.; Fremling, C.; Migotto, K.; Gal-Yam, A.; Armen, S.; Duggan, G.; Ergon, M.; Filippenko, A. V.; Fransson, C.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Leloudas, G.; Leonard, D. C.; Lunnan, R.; Masci, F. J.; Moon, D.-S.; Silverman, J. M.; Wozniak, P. R.

    2016-04-01

    Context. Supernova (SN) 1987A was a peculiar hydrogen-rich event with a long-rising (~84 d) light curve, stemming from the explosion of a compact blue supergiant star. Only a few similar events have been presented in the literature in recent decades. Aims: We present new data for a sample of six long-rising Type II SNe (SNe II), three of which were discovered and observed by the Palomar Transient Factory (PTF) and three observed by the Caltech Core-Collapse Project (CCCP). Our aim is to enlarge this small family of long-rising SNe II, characterizing their differences in terms of progenitor and explosion parameters. We also study the metallicity of their environments. Methods: Optical light curves, spectra, and host-galaxy properties of these SNe are presented and analyzed. Detailed comparisons with known SN 1987A-like events in the literature are shown, with particular emphasis on the absolute magnitudes, colors, expansion velocities, and host-galaxy metallicities. Bolometric properties are derived from the multiband light curves. By modeling the early-time emission with scaling relations derived from the SuperNova Explosion Code (SNEC) models of MESA progenitor stars, we estimate the progenitor radii of these transients. The modeling of the bolometric light curves also allows us to estimate other progenitor and explosion parameters, such as the ejected 56Ni mass, the explosion energy, and the ejecta mass. Results: We present PTF12kso, a long-rising SN II that is estimated to have the largest amount of ejected 56Ni mass measured for this class. PTF09gpn and PTF12kso are found at the lowest host metallicities observed for this SN group. The variety of early light-curve luminosities depends on the wide range of progenitor radii of these SNe, from a few tens of R⊙ (SN 2005ci) up to thousands (SN 2004ek) with some intermediate cases between 100 R⊙ (PTF09gpn) and 300 R⊙ (SN 2004em). Conclusions: We confirm that long-rising SNe II with light-curve shapes closely

  5. Transient Response of Cadmium Telluride Modules to Light Exposure: Preprint

    SciTech Connect

    Deline, C.; del Cueto, J.; Albin, D. S.; Petersen, C.; Tyler, L.; TamizhMani, G.

    2011-07-01

    Commercial cadmium telluride (CdTe) photovoltaic (PV) modules from three different manufacturers were monitored for performance changes during indoor and outdoor light-exposure. Short-term transients in Voc were recorded on some modules, with characteristic times of ~1.1 hours. Outdoor performance data shows a similar drop in Voc after early morning light exposure. Preliminary analysis of FF changes show light-induced changes on multiple time scales, including a long time scale.

  6. Transient response of high temperature PEM fuel cell

    NASA Astrophysics Data System (ADS)

    Peng, J.; Shin, J. Y.; Song, T. W.

    A transient three-dimensional, single-phase and non-isothermal numerical model of polymer electrolyte membrane (PEM) fuel cell with high operating temperature has been developed and implemented in computational fluid dynamic (CFD) code. The model accounts for transient convective and diffusive transport, and allows prediction of species concentration. Electrochemical charge double-layer effect is considered. Heat generation according to electrochemical reaction and ohmic loss are involved. Water transportation across membrane is ignored due to low water electro-osmosis drag force of polymer polybenzimidazole (PBI) membrane. The prediction shows transient in current density which overshoots (undershoots) the stabilized state value when cell voltage is abruptly decreased (increased). The result shows that the peak of overshoot (undershoot) is related with cathode air stoichiometric mass flow rate instead of anode hydrogen stoichiometric mass flow rate. Current is moved smoothly and there are no overshoot or undershoot with the influence of charge double-layer effect. The maximum temperature is located in cathode catalyst layer and both fuel cell average temperature and temperature deviation are increased with increasing of current load.

  7. A review of progress towards understanding the transient global mean surface temperature response to radiative perturbation

    NASA Astrophysics Data System (ADS)

    Yoshimori, Masakazu; Watanabe, Masahiro; Shiogama, Hideo; Oka, Akira; Abe-Ouchi, Ayako; Ohgaito, Rumi; Kamae, Youichi

    2016-12-01

    The correct understanding of the transient response to external radiative perturbation is important for the interpretation of observed climate change, the prediction of near-future climate change, and committed warming under climate stabilization scenarios, as well as the estimation of equilibrium climate sensitivity based on observation data. It has been known for some time that the radiative damping rate per unit of global mean surface temperature increase varies with time, and this inconstancy affects the transient response. Knowledge of the equilibrium response alone is insufficient, but understanding the transient response of the global mean surface temperature has made rapid progress. The recent progress accompanies the relatively new concept of the efficacies of ocean heat uptake and forcing. The ocean heat uptake efficacy associates the temperature response induced by ocean heat uptake with equilibrium temperature response, and the efficacy of forcing compares the temperature response caused by non-CO2 forcing with that by CO2 forcing.

  8. The Coda of the Transient Response in a Sensitive Cochlea: A Computational Modeling Study

    PubMed Central

    Li, Yizeng; Grosh, Karl

    2016-01-01

    In a sensitive cochlea, the basilar membrane response to transient excitation of any kind–normal acoustic or artificial intracochlear excitation–consists of not only a primary impulse but also a coda of delayed secondary responses with varying amplitudes but similar spectral content around the characteristic frequency of the measurement location. The coda, sometimes referred to as echoes or ringing, has been described as a form of local, short term memory which may influence the ability of the auditory system to detect gaps in an acoustic stimulus such as speech. Depending on the individual cochlea, the temporal gap between the primary impulse and the following coda ranges from once to thrice the group delay of the primary impulse (the group delay of the primary impulse is on the order of a few hundred microseconds). The coda is physiologically vulnerable, disappearing when the cochlea is compromised even slightly. The multicomponent sensitive response is not yet completely understood. We use a physiologically-based, mathematical model to investigate (i) the generation of the primary impulse response and the dependence of the group delay on the various stimulation methods, (ii) the effect of spatial perturbations in the properties of mechanically sensitive ion channels on the generation and separation of delayed secondary responses. The model suggests that the presence of the secondary responses depends on the wavenumber content of a perturbation and the activity level of the cochlea. In addition, the model shows that the varying temporal gaps between adjacent coda seen in experiments depend on the individual profiles of perturbations. Implications for non-invasive cochlear diagnosis are also discussed. PMID:27380177

  9. A transient laboratory method for determining the hydraulic properties of 'tight' rocks-II. Application

    USGS Publications Warehouse

    Neuzil, C.E.; Cooley, C.; Silliman, S.E.; Bredehoeft, J.D.; Hsieh, P.A.

    1981-01-01

    In Part I a general analytical solution for the transient pulse test was presented. Part II presents a graphical method for analyzing data from a test to obtain the hydraulic properties of the sample. The general solution depends on both hydraulic conductivity and specific storage and, in theory, analysis of the data can provide values for both of these hydraulic properties. However, in practice, one of two limiting cases may apply in which case it is possible to calculate only hydraulic conductivity or the product of hydraulic conductivity times specific storage. In this paper we examine the conditions when both hydraulic parameters can be calculated. The analyses of data from two tests are presented. In Appendix I the general solution presented in Part I is compared with an earlier analysis, in which compressive storage in the sample is assumed negligible, and the error in calculated hydraulic conductivity due to this simplifying assumption is examined. ?? 1981.

  10. Transient absorption studies of the primary charge separation in photosystem II

    SciTech Connect

    Donovan, B.; Walker, L.A. II; Yocum, C.F.; Sension, R.J.

    1996-02-01

    Femtosecond transient absorption studies of the primary charge separation in photosystem II (PSII) are presented. A careful study of the dependence of the observed signal on laser intensity demonstrates that the multiple excitation of reaction centers produces additional fast components not observed at low excitation energy. In the regime where the observed signals are linear with excitation energy, a 20 {+-} 2 ps rise of the pheophytin anion absorption, bleach of the pheophytin Q{sub {chi}} absorption, and appearance of the chlorophyll cation absorption are observed. Three different protocols, involving varying exposure of the PSII complex to the detergent Triton X-100, are used to prepare D1-D2-cyt b{sub 559} complexes from spinach. The kinetic signals are independent of the method of sample preparation. 35 refs., 5 figs.

  11. Transient analyses for HEU and LEU designs of the FRM-II.

    SciTech Connect

    Hanan, N. A.

    1998-10-14

    An Alternative LEU Design for the FRM-II proposed by the RERTR Program at Argonne National Laboratory (ANL) has a compact core consisting of a single fuel element that uses LEU silicide fuel with a uranium density of 4.5 g/cm{sup 3} and has a power level of 32 MW. Both the HEU design by the Technical University of Munich (TUM) and the alternative LEU design by ANL have the same fuel lifetime (50 days) and the same neutron flux performance (8 x 10{sup 14} n/cm{sup 2}-s in the reflector). LEU silicide fuel with 4.5 g/cm{sup 3} has been thoroughly tested and is fully-qualified, licensable, and available now for use in a high flux reactor such as the FRM-II. Several issues raised by TUM have been addressed in Refs. 1-4. The conclusions of these analyses are summarized below. In this paper, two typical design basis transients are analyzed: control rod withdrawal at different power levels and loss of primary flow. The results show that the HEU and the LEU cores behave in a similar manner and both have excellent safety margins. Based on the excellent results for the Alternative LEU Design that were obtained in all analyses, the RERTR Program reiterates its conclusion that there are no major technical issues regarding use of LEU fuel instead of HEU fuel in the FRM-II and that it is definitely feasible to use LEU fuel in the FRM-II without compromising the safety or performance of the facility.

  12. RETRAN analysis of Susquehanna Steam Electric Station Unit 2 moisture separator drain tank level transient response

    SciTech Connect

    Olson, L.M.

    1987-01-01

    Susquehanna Steam Electric Station Unit 2 (SSES-2) experienced three main turbine trips on high moisture separator drain tank level during initial startup testing in 1984. The SSES-2, a 3293-MW (thermal) boiling water reactor-4 with Mark II containment, uses two parallel nonreheating moisture separators between the high- and low-pressure turbine stages. Two of the main turbine trips and subsequent scrams occurred due to the high level in the ''B'' moisture separator drain tank during combined intermediate valve testing. The third trip was also initiated on the same signal, but during a recirculation pump runback event. A task group was created to determine the cause of the level excursions and to make recommendations to reduce the severity of these transients. The RETRAN-02 computer code was used to evaluate the dynamic response of both the A and B moisture separator drain systems to determine the cause of the events, including why the level excursions only occurred in the B system. RETRAN was also used to evaluate the systems' dynamic response to several proposed corrective plant modifications. Based on the recommendations of the task group, modifications were made to SSES-2 during the precommercial operation outage. Startup testing following the outage proved the success of the modifications.

  13. Transient coaxial helicity injection for solenoid-free plasma startup in HIT-II

    SciTech Connect

    Raman, R.; Jarboe, T. R; Hamp, W. T.; Redd, A. J.; Nelson, B. A.; O'Neill, R. G.; Sieck, P. E.; Smith, R. J.

    2007-02-15

    The favorable properties of the spherical torus (ST) arise from its very small aspect ratio. Methods for initiating the plasma current without relying on induction from a central solenoid are essential for the viability of the ST concept. In steady state tokamaks, the central solenoid can be dispensed with if suitable methods for initiating the plasma current are on hand. Coaxial helicity injection (CHI) is a promising candidate for solenoid-free plasma current startup in STs and tokamaks. Experiments on the Helicity Injected Torus (HIT-II) machine at the University of Washington [T. R. Jarboe, Fusion Technol. 15, 7 (1989)] have demonstrated the capability of a new method, referred to as transient CHI, to produce a high quality closed-flux equilibrium that has been successfully coupled to induction demonstrating that this new plasma current startup method is compatible with the conventional inductive method. This paper presents physics requirements for implementing this method in STs and tokamaks and supporting experimental results from the HIT-II device.

  14. Dynamic asymmetries of cardiac output transients in response to muscular exercise in man.

    PubMed Central

    Yoshida, T; Whipp, B J

    1994-01-01

    1. We determined the kinetics of cardiac output (Q) with respect to oxygen uptake (VO2) at the on- and off-transients of constant-load exercise. Six subjects performed constant-load exercise which consisted of 5 min rest, 5 min one-legged pedalling at 50 W and a 5 min recovery period. 2. The transient responses were characterized by first-order kinetics. There was no significant difference between the time constants for VO2 (tau VO2) at the on- (33.9 +/- 3.5 s, mean +/- S.E.M.) and off-transient (37.2 +/- 2.9 s). The time constant for Q (tau Q, 29.4 +/- 3.2 s) was consistently shorter than tau VO2 at the on-transient. However, tau Q was appreciably longer at the off-transient (44.3 +/- 3.6 s) than the on-transient. 3. The results support the contention that the time constant for the on-transient of Q is appreciably faster than that for VO2 and hence there seems little justification for the notion that the time constants for the kinetics of VO2 are determined by the limitations of blood flow in the transient. The asymmetry of Q kinetics, with the off-transient tau Q being appreciably slower than the on-transient tau Q, serves to maintain a sufficiently high oxygen flow to the muscle during recovery from exercise at a time when the muscle oxygen uptake remains high. PMID:7869250

  15. I got it! Transient cardiovascular response to the perception of humor.

    PubMed

    Lackner, Helmut K; Weiss, Elisabeth M; Schulter, Günter; Hinghofer-Szalkay, Helmut; Samson, Andrea C; Papousek, Ilona

    2013-04-01

    The aim of the present study was to examine the transient cardiovascular response to the perception of humor, that is, the impact of the cognitive process of insight as well as the modulation of the response by the affective appraisal of the humor. To this end transient heart rate, stroke volume, cardiac output, and blood pressure responses were obtained in the immediate context of detecting the punch line in cartoons. Fine-grained analysis of the transient behavior of cardiovascular variables during viewing the cartoons was contrasted to non-humorous cartoon-like pictures. The detection of a punch line was accompanied by relative heart rate acceleration in conjunction with increased cardiac output, which was more pronounced the more amusing the cartoons were perceived. These results provide first evidence of the usefulness of cardiovascular variables for detecting the moment of insight and the quantification of the size of the emotional response accompanying it.

  16. Numerical Analysis of Transient Temperature Response of Soap Film

    NASA Astrophysics Data System (ADS)

    Tanaka, Seiichi; Tatesaku, Akihiro; Dantsuka, Yuki; Fujiwara, Seiji; Kunimine, Kanji

    2015-11-01

    Measurements of thermophysical properties of thin liquid films are important to understand interfacial phenomena due to film structures composed of amphiphilic molecules in soap film, phospholipid bilayer of biological cell and emulsion. A transient hot-wire technique for liquid films less than 1 \\upmu m thick such as soap film has been proposed to measure the thermal conductivity and diffusivity simultaneously. Two-dimensional heat conduction equations for a solid cylinder with a liquid film have been solved numerically. The temperature of a thin wire with liquid film increases steeply with its own heat generation. The feasibility of this technique is verified through numerical experiments for various thermal conductivities, diffusivities, and film thicknesses. Calculated results indicate that the increase in the volumetric average temperature of the thin wire sufficiently varies with the change of thermal conductivity and diffusivity of the soap film. Therefore, the temperature characteristics could be utilized to evaluate both the thermal conductivity and diffusivity using the Gauss-Newton method.

  17. Transient response of sand bedforms to changes in flow

    NASA Astrophysics Data System (ADS)

    Martin, R. L.; Jerolmack, D. J.

    2011-12-01

    Lowland rivers commonly experience discharge variability spanning more than an order of magnitude, producing correspondingly large changes in bed morphology. However, field and lab studies indicate that bedform geometries lag changes in flow, producing hysteretic relationships between bed morphology, roughness, and water discharge. The ability of bedforms to maintain equilibrium with hydrodynamic flow variability thus depends on the timescale of transient bedform adjustment to flow. Here, we present results of flume experiments carried out at the Saint Anthony Falls Laboratory, University of Minnesota, in which we continuously tracked adjustment of sand bedform morphologies to abrupt changes in water discharge. We show how the timescale of bedform adjustment is driven by three primary factors: 1. directionality of adjustment, 2. preexisting bedform geometry, and 3. sediment flux. Directionality of adjustment (rising versus falling water discharge) determines whether bedforms grow quickly by irreversible merger (rising flows) or shrink slowly through secondary bedform cannibalization of relict larger bedforms (falling flows). Preexisting bedform geometry (height and length) determines the amount of bed deformation required for adjustment to new equilibrium, and sediment flux determines the rate at which this change is affected. These three factors all favor faster adjustment of bedforms to rising flows. We experimentally demonstrate this bedform adjustment hysteresis through a variety of increasing and decreasing discharge changes, across both sand ripple and dune regimes. Finally, we propose and validate a simple conceptual model for estimating the adjustment timescale based on sediment flux and equilibrium bedform geometry.

  18. Development of transient phage resistance in Campylobacter coli against the group II phage CP84.

    PubMed

    Orquera, Stefanie; Hertwig, Stefan; Alter, Thomas; Hammerl, Jens A; Jirova, Alice; Gölz, Greta

    2015-01-01

    Recently, there is a growing interest in the use of bacteriophages for pre- and post-harvest applications to reduce foodborne pathogens (including Campylobacter) along the food chain. Quantitative Campylobacter reductions of up to three log10 units have been achieved by phage application. However, possible phage resistance might limit this approach. In Campylobacter (C.) jejuni, phage resistance mechanisms have been described in detail but data on these mechanisms in C. coli are still missing. To study phage resistance in C. coli, strain NCTC 12668 was infected with the lytic phage CP84, belonging to group II of Campylobacter phages. Resistant and sensitive clones were analysed using phenotypic and genotypic assays. C. coli clones acquired only transient resistance against CP84. The resistance led to cross-protection to one out of five other group II phages tested. Phage resistance was apparently neither caused by large genomic rearrangements nor by a CRISPR system. Binding assays demonstrated that CP84 could not adsorb to resistant C. coli clones suggesting a bacterial phage receptor to be involved in resistance. However, phage resistant C. coli clones did not reveal an altered motility or modified flaA sequence. Considering the loss of binding capacity and the reversion to a phage sensitive phenotype we hypothesize that acquired resistance depends on temporal phase variable switch-off modifications of the phage receptor genes, even though the resistance mechanism could not be elucidated in detail. We further speculate that even closely related phages of the same group use different bacterial receptors for binding on C. coli.

  19. Angiotensin II-stimulated Ca2+ entry mechanisms in afferent arterioles: role of transient receptor potential canonical channels and reverse Na+/Ca2+ exchange.

    PubMed

    Fellner, Susan K; Arendshorst, William J

    2008-01-01

    In afferent arterioles, the signaling events that lead to an increase in cytosolic Ca(2+) concentration ([Ca(2+)](i)) and initiation of vascular contraction are increasingly being delineated. We have recently studied angiotensin II (ANG II)-mediated effects on sarcoplasmic reticulum (SR) mobilization of Ca(2+) and the role of superoxide and cyclic adenosine diphosphoribose in these processes. In the current study we investigated the participation of transient receptor potential canonical channels (TRPC) and a Na(+)/Ca(2+) exchanger (NCX) in Ca(2+) entry mechanisms. Afferent arterioles, isolated with the magnetized polystyrene bead method, were loaded with fura-2 to measure [Ca(2+)](i) ratiometrically. We observed that the Ca(2+)-dependent chloride channel blocker niflumic acid (10 and 50 microM) affects neither the peak nor plateau [Ca(2+)](i) response to ANG II. Arterioles were pretreated with ryanodine (100 microM) and TMB-8 to block SR mobilization via the ryanodine receptor and inositol trisphosphate receptor, respectively. The peak [Ca(2+)](i) response to ANG II was reduced by 40%. Addition of 2-aminoethoxydiphenyl borane to block TRPC-mediated Ca(2+) entry inhibited the peak [Ca(2+)](i) ANG II response by 80% and the plateau by 74%. Flufenamic acid (FFA; 50 microM), which stimulates TRPC6, caused a sustained increase of [Ca(2+)](i) of 146 nM. This response was unaffected by diltiazem or nifedipine. KB-R7943 (at the low concentration of 10 microM) inhibits reverse (but not forward) mode NCX. KB-R7943 decreased the peak [Ca(2+)](i) response to ANG II by 48% and to FFA by 38%. We conclude that TRPC6 and reverse-mode NCX may be important Ca(2+) entry pathways in afferent arterioles.

  20. A numerical and experimental investigation of premixed methane-air flame transient response

    SciTech Connect

    Habib N. Najm; Phillip H. Paul; Omar M. Knio; Andrew McIlroy

    2000-01-06

    The authors report the results of a numerical and experimental investigation of the response of premixed methane-air flames to transient strain-rate disturbances induced by a two-dimensional counter-rotating vortex-pair. The numerical and experimental time histories of flow and flame evolution are matched over a 10 ms interaction time. Measurements and computations of CH and OH peak data evolution are reported, and found to indicate mis-prediction of the flame time scales in the numerical model. Qualitative transient features of OH at rich conditions are not predicted in the computations. On the other hand, evolution of computed and measured normalized HCO fractions are in agreement. The computed CH{sub 3}O response exhibits a strong transient driven by changes to internal flame structure, namely temperature profile steepening, induced by the flow field. Steady state experimental PLIF CH{sub 3}O data is reported, but experimental transient CH{sub 3}O data is not available. The present analysis indicates that the flame responds at time scales that are quite distinct from ``propagation'' time scale derived from flame thickness and burning speed. Evidently, these propagation time scales are not adequate for characterizing the transient flame response.

  1. High-speed LWR transients simulation for optimizing emergency response

    SciTech Connect

    Wulff, W.; Cheng, H.S.; Lekach, S.V.; Mallen, A.N.; Stritar, A.

    1984-11-19

    The purpose of computer-assisted emergency response in nuclear power plants, and the requirements for achieving such a response, are presented. An important requirement is the attainment of realistic high-speed plant simulations at the reactor site. Currently pursued development programs for plant simulations are reviewed. Five modeling principles are established and a criterion is presented for selecting numerical procedures and efficient computer hardware to achieve high-speed simulations. A newly developed technology for high-speed power plant simulation is described and results are presented. It is shown that simulation speeds ten times greater than real-time process-speeds are possible, and that plant instrumentation can be made part of the computational loop in a small, on-site minicomputer. Additional technical issues are presented which must still be resolved before the newly developed technology can be implemented in a nuclear power plant.

  2. On Solutions for the Transient Response of Beams

    NASA Technical Reports Server (NTRS)

    Leonard, Robert W.

    1959-01-01

    Williams type modal solutions of the elementary and Timoshenko beam equations are presented for the response of several uniform beams to a general applied load. Example computations are shown for a free-free beam subject to various concentrated loads at its center. Discussion includes factors influencing the convergence of modal solutions and factors to be considered in a choice of beam theory. Results obtained by two numerical procedures, the traveling-wave method and Houbolt's method, are also presented and discussed.

  3. Transient Response Dynamic Module Modifications to Include Static and Kinetic Friction Effects

    NASA Technical Reports Server (NTRS)

    Misel, J. E.; Nenno, S. B.; Takahashi, D.

    1984-01-01

    A methodology that supports forced transient response dynamic solutions when both static and kinetic friction effects are included in a structural system model is described. Modifications that support this type of nonlinear transient response solution are summarized for the transient response dynamics (TRD) NASTRAN module. An overview of specific modifications for the NASTRAN processing subroutines, INITL, TRD1C, and TRD1D, are described with further details regarding inspection of nonlinear input definitions to define the type of nonlinear solution required, along with additional initialization requirements and specific calculation subroutines to successfully solve the transient response problem. The extension of the basic NASTRAN nonlinear methodology is presented through several stages of development to the point where constraint equations and residual flexibility effects are introduced into the finite difference Newmark-Beta recurrsion formulas. Particular emphasis is placed on cost effective solutions for large finite element models such as the Space Shuttle with friction degrees of freedom between the orbiter and payloads mounted in the cargo bay. An alteration to the dynamic finite difference equations of motion is discussed, which allows one to include friction effects at reasonable cost for large structural systems such as the Space Shuttle. Data are presented to indicate the possible impact of transient friction loads to the payload designer for the Space Shuttle. Transient response solution data are also included, which compare solutions without friction forces and those with friction forces for payloads mounted in the Space Shuttle cargo bay. These data indicate that payload components can be sensitive to friction induced loads.

  4. Distinguishing cells by their first-order transient motion response under an optically induced dielectrophoretic force field

    NASA Astrophysics Data System (ADS)

    Zhao, Yuliang; Liang, Wenfeng; Zhang, Guanglie; Mai, John D.; Liu, Lianqing; Lee, Gwo-Bin; Li, Wen J.

    2013-10-01

    This letter reports our characterization of the transient motion of cells under an optically induced dielectrophoresis (ODEP) force field. Different types of human cells repeatably undergo a first-order transient motion response when subjected to a specific ODEP force field. A kernel function is derived to describe this transient motion. This function can be generally matched to experimental data for Raji cells and red blood cells by measuring two parameters: the initial velocity and the transient time-constant. They are uniquely different for Raji cells and RBCs. Support vector machine is used to distinguish between them based on their transient response characteristics.

  5. Assessment of RELAP5/MOD2 against a main feedwater turbopump trip transient in the Vandellos II Nuclear Power Plant

    SciTech Connect

    Llopis, C.; Casals, A.; Perez, J.; Mendizabal, R.

    1993-12-01

    The Consejo de Seguridad Nuclear (CSN) and the Asociacion Nuclear Vandellos (ANV) have developed a model of Vandellos II Nuclear Power Plant. The ANV collaboration consisted in the supply of design and actual data, the cooperation in the simulation of the control systems and other model components, as well as in the results analysis. The obtained model has been assessed against the following transients occurred in plant: A trip from the 100% power level (CSN); a load rejection from 100% to 50% (CSN); a load rejection from 75% to 65% (ANV); and, a feedwater turbopump trip (ANV). This copy is a report of the feedwater turbopump trip transient simulation. This transient actually occurred in the plant on June 19, 1989.

  6. Transient response of a plate convolved with a mechanical shaker using high speed optical interferometry

    NASA Astrophysics Data System (ADS)

    Perez-Lopez, C.; Sanchez Preciado, J.

    2015-08-01

    Transient response analysis is widely used in mechanical systems; with a single stimulation the mechanical behavior of the system could be characterized. Commonly, the entrance used in transient systems is a delta function, due to the possibility of stimulate the system in a wide range of frequencies. Unfortunately, the Dirac function is not easy to achieve. For this work we stimulated a mechanical shaker with a step function obtaining a Gaussian-type displacement of the spike. The spike is then used as the entrance signal for a square elastic plate. The measurement of the convolved transient response of an elastic plate is obtained by means of a high speed camera working at 10,000 fps with an out of plane speckle interferometer. Experimental results are shown.

  7. Information conveyed by onset transients in responses of striate cortical neurons.

    PubMed

    Müller, J R; Metha, A B; Krauskopf, J; Lennie, P

    2001-09-01

    Normal eye movements ensure that the visual world is seen episodically, as a series of often stationary images. In this paper we characterize the responses of neurons in striate cortex to stationary grating patterns presented with abrupt onset. These responses are distinctive. In most neurons the onset of a grating gives rise to a transient discharge that decays with a time constant of 100 msec or less. The early stages of response have higher contrast gain and higher response gain than later stages. Moreover, the variability of discharge during the onset transient is disproportionately low. These factors together make the onset transient an information-rich component of response, such that the detectability and discriminability of stationary gratings grows rapidly to an early peak, within 150 msec of the onset of the response in most neurons. The orientation selectivity of neurons estimated from the first 150 msec of discharge to a stationary grating is indistinguishable from the orientation selectivity estimated from longer segments of discharge to moving gratings. Moving gratings are ultimately more detectable than stationary ones, because responses to the former are continuously renewed. The principal characteristics of the response of a neuron to a stationary grating-the initial high discharge rate, which decays rapidly, and the change of contrast gain with time-are well captured by a model in which each excitatory synaptic event leads to an immediate reduction in synaptic gain, from which recovery is slow.

  8. Transient response of an electrodynamic tether system in the ionosphere: TSS-1 first results

    NASA Astrophysics Data System (ADS)

    BiléN, Sven G.; Gilchrist, Brian E.; Bonifazi, Carlo; Melchioni, Enrico

    1995-09-01

    The electrical transient response of an electrodynamic tether system in low earth orbit has been investigated experimentally and by computer simulation. Our experimental results come from the first Tethered Satellite System (TSS-1) mission flown on the space shuttle in 1992. During this mission a tethered satellite was deployed to a distance of 267 m above the shuttle using a conducting, insulated cable. It is shown by computer simulation that the electrical transient response of the system is due to a combination of both the tether electrical circuit and the interaction of the tether system with the space plasma. In general, ground measurements showed that the TSS-1 electrical circuit is approximately second order and underdamped. However, it was found that on-orbit transient decay as well as the symmetry of transient oscillations could be dramatically altered, following closely with ionospheric plasma density variations. Combined electrical circuit and plasma interaction modeling shows that these differences can be explained by accounting for ion and electron current collection capabilities of the tether end connections with the space plasma. These results have implications for the use of electrodynamic tethers for high current switched applications including direct generation of low-frequency electromagnetic signals and high electrical power generation as well as detection of natural electric field transient signatures.

  9. Neurocognitive Brain Response to Transient Impairment of Wernicke's Area

    PubMed Central

    Mason, Robert A.; Prat, Chantel S.; Just, Marcel Adam

    2014-01-01

    This study examined how the brain system adapts and reconfigures its information processing capabilities to maintain cognitive performance after a key cortical center [left posterior superior temporal gyrus (LSTGp)] is temporarily impaired during the performance of a language comprehension task. By applying repetitive transcranial magnetic stimulation (rTMS) to LSTGp and concurrently assessing the brain response with functional magnetic resonance imaging, we found that adaptation consisted of 1) increased synchronization between compensating regions coupled with a decrease in synchronization within the primary language network and 2) a decrease in activation at the rTMS site as well as in distal regions, followed by their recovery. The compensatory synchronization included 3 centers: The contralateral homolog (RSTGp) of the area receiving rTMS, areas adjacent to the rTMS site, and a region involved in discourse monitoring (medial frontal gyrus). This approach reveals some principles of network-level adaptation to trauma with potential application to traumatic brain injury, stroke, and seizure. PMID:23322403

  10. Transient response of an active nonlinear sandwich piezolaminated plate

    NASA Astrophysics Data System (ADS)

    Oveisi, Atta; Nestorović, Tamara

    2017-04-01

    In this paper, the dynamic modelling and active vibration control of a piezolaminated plate with geometrical nonlinearities are investigated using a semi-analytical approach. For active vibration control purposes, the core orthotropic elastic layer is assumed to be perfectly bonded with two piezo-layers on its top and bottom surfaces which act as sensor and actuator, respectively. In the modelling procedure, the piezo-layers are assumed to be connected via a proportional derivative (PD) feedback control law. Hamilton's principle is employed to acquire the strong form of the dynamic equation in terms of additional higher order strain expressions by means of von Karman strain-displacement correlation. The obtained nonlinear partial differential equation (NPDE) is converted to a system of nonlinear ordinary differential equations (NODEs) by engaging Galerkin method and using the orthogonality of shape functions for the simply supported boundary conditions. Then, the resulting system of NODEs is solved numerically by employing the built-in Mathematica function, "NDSolve". Next, the vibration attenuation performance is evaluated and sensitivity of the closed-loop system is investigated for several control parameters and the external disturbance parameters. The proposed solution in open loop configuration is validated by finite element (FE) package ABAQUS both in the spatial domain and for the time-/frequency-dependent response.

  11. Exciton exciton annihilation dynamics in chromophore complexes. II. Intensity dependent transient absorption of the LH2 antenna system.

    PubMed

    Bruggemann, B; May, V

    2004-02-01

    Using the multiexciton density matrix theory of excitation energy transfer in chromophore complexes developed in a foregoing paper [J. Chem. Phys. 118, 746 (2003)], the computation of ultrafast transient absorption spectra is presented. Beside static disorder and standard mechanisms of excitation energy dissipation the theory incorporates exciton exciton annihilation (EEA) processes. To elucidate signatures of EEA in intensity dependent transient absorption data the approach is applied to the B850 ring of the LH2 found in rhodobacter sphaeroides. As main indications for two-exciton population and resulting EEA we found (i) a weakening of the dominant single-exciton bleaching structure in the transient absorption, and (ii) an intermediate suppression of long-wavelength and short-wavelength shoulders around the bleaching structure. The suppression is caused by stimulated emission from the two-exciton to the one-exciton state and the return of the shoulders follows from a depletion of two-exciton population according to EEA. The EEA-signature survives as a short-wavelength shoulder in the transient absorption if orientational and energetic disorder are taken into account. Therefore, the observation of the EEA-signatures should be possible when doing frequency resolved transient absorption experiments with a sufficiently strongly varying pump-pulse intensity.

  12. Review of behavior of mixed-oxide fuel elements in extended overpower transient tests in EBR-II

    SciTech Connect

    Tsai, H.; Neimark, L.A.; Nagai, S.; Nakae, N.

    1994-10-01

    From a series of five tests conducted in EBR-II, a substantial data base has been established on the performance of mixed-oxide fuel elements in a liquid-metal-cooled reactor under slow-ramp transient overpower conditions. Each test contained 19 preirradiated fuel elements with varying design and prior operating histories. Elements with aggressive design features, such as high fuel smear density and/or thin cladding, were included to accentuate transient effects. The ramp rates were either 0.1 or 10% {Delta}P/P/s and the overpowers ranged between {approx}60 and 100% of the elements` prior power ratings. Six elements breached during the tests, all with aggressive design parameters. The other elements, including all those with moderate design features for the reference or advanced long-life drivers for PNC`s prototype fast reactor Monju, maintained their cladding integrity during the tests. Posttest examination results indicated that fuel/cladding mechanical interaction (FCMI) was the most significant mechanism causing the cladding strain and breach. In contrast, pressure loading from the fission gas in the element plenum was less important, even in high-burnup elements. During an overpower transient, FCMI arises from fuel/cladding differential thermal expansion, transient fuel swelling, and, significantly, the gas pressure in the sealed central cavity of elements with substantial centerline fuel melting. Fuel performance data from these tests, including cladding breaching margin and transient cladding strain, are correlatable with fuel-element design and operating parameters. These correlations are being incorporated into fuel-element behavior codes. At the two tested ramp rates, fuel element behavior appears to be insensitive to transient ramp rate and there appears to be no particular vulnerability to slow ramp transients as previously perceived.

  13. Transient PVT measurements and model predictions for vessel heat transfer. Part II.

    SciTech Connect

    Felver, Todd G.; Paradiso, Nicholas Joseph; Winters, William S., Jr.; Evans, Gregory Herbert; Rice, Steven F.

    2010-07-01

    Part I of this report focused on the acquisition and presentation of transient PVT data sets that can be used to validate gas transfer models. Here in Part II we focus primarily on describing models and validating these models using the data sets. Our models are intended to describe the high speed transport of compressible gases in arbitrary arrangements of vessels, tubing, valving and flow branches. Our models fall into three categories: (1) network flow models in which flow paths are modeled as one-dimensional flow and vessels are modeled as single control volumes, (2) CFD (Computational Fluid Dynamics) models in which flow in and between vessels is modeled in three dimensions and (3) coupled network/CFD models in which vessels are modeled using CFD and flows between vessels are modeled using a network flow code. In our work we utilized NETFLOW as our network flow code and FUEGO for our CFD code. Since network flow models lack three-dimensional resolution, correlations for heat transfer and tube frictional pressure drop are required to resolve important physics not being captured by the model. Here we describe how vessel heat transfer correlations were improved using the data and present direct model-data comparisons for all tests documented in Part I. Our results show that our network flow models have been substantially improved. The CFD modeling presented here describes the complex nature of vessel heat transfer and for the first time demonstrates that flow and heat transfer in vessels can be modeled directly without the need for correlations.

  14. Equilibrium Response and Transient Dynamics Datasets from VEMAP: Vegetation/Ecosystem Modeling and Analysis Project

    DOE Data Explorer

    The Vegetation-Ecosystem Modeling and Analysis Project (VEMAP) was a large, collaborative, multi-agency program to simulate and understand ecosystem dynamics for the continental U.S. The project involved the development of common data sets for model input including a high-resolution topographically-adjusted climate history of the U.S. from 1895-1993 on a 0.5? grid, with soils and vegetation cover. The vegetation cover data set includes a detailed agricultural data base based on USDA statistics and remote sensing, as well as natural vegetation (also derived from satellite imagery). Two principal model experiments were run. First, a series of ecosystem models were run from 1895 to 1993 to simulate current ecosystem biogeochemistry. Second, these same models were integrated forward using the output from two climate system models (CCC (Canadian Climate Centre) and Hadley Centre models) using climate results translated into the VEMAP grid and re-adjusted for high-resolution topography for the simulated period 1994-2100.[Quoted from http://www.cgd.ucar.edu/vemap/findings.html] The VEMAP Data Portal is a central collection of files maintained and serviced by the NCAR Data Group. These files (the VEMAP Community Datasets) represent a complete and current collection of VEMAP data files. All data files available through the Data Portal have undergone extensive quality assurance.[Taken from http://www.cgd.ucar.edu/vemap/datasets.html] Users of the VEMAP Portal can access input files of numerical data that include monthly and daily files of geographic data, soil and site files, scenario files, etc. Model results from Phase I, the Equilibrium Response datasets, are available through the NCAR anonymous FTP site at http://www.cgd.ucar.edu/vemap/vresults.html. Phase II, Transient Dynamics, include climate datasets, models results, and analysis tools. Many supplemental files are also available from the main data page at http://www.cgd.ucar.edu/vemap/datasets.html.

  15. Complex transient dynamics of stage-structured populations in response to environmental changes.

    PubMed

    Massie, Thomas M; Ryabov, Alexei; Blasius, Bernd; Weithoff, Guntram; Gaedke, Ursula

    2013-07-01

    Stage structures of populations can have a profound influence on their dynamics. However, not much is known about the transient dynamics that follow a disturbance in such systems. Here we combined chemostat experiments with dynamical modeling to study the response of the phytoplankton species Chlorella vulgaris to press perturbations. From an initially stable steady state, we altered either the concentration or dilution rate of a growth-limiting resource. This disturbance induced a complex transient response-characterized by the possible onset of oscillations-before population numbers relaxed to a new steady state. Thus, cell numbers could initially change in the opposite direction of the long-term change. We present quantitative indexes to characterize the transients and to show that the dynamic response is dependent on the degree of synchronization among life stages, which itself depends on the state of the population before perturbation. That is, we show how identical future steady states can be approached via different transients depending on the initial population structure. Our experimental results are supported by a size-structured model that accounts for interplay between cell-cycle and population-level processes and that includes resource-dependent variability in cell size. Our results should be relevant to other populations with a stage structure including organisms of higher order.

  16. Computer experiments on periodic systems identification using rotor blade transient flapping-torsion responses at high advance ratio

    NASA Technical Reports Server (NTRS)

    Hohenemser, K. H.; Prelewicz, D. A.

    1974-01-01

    Systems identification methods have recently been applied to rotorcraft to estimate stability derivatives from transient flight control response data. While these applications assumed a linear constant coefficient representation of the rotorcraft, the computer experiments described in this paper used transient responses in flap-bending and torsion of a rotor blade at high advance ratio which is a rapidly time varying periodic system.

  17. Heat changes during transient tension responses to small releases in active frog muscle.

    PubMed Central

    Gilbert, S H; Ford, L E

    1988-01-01

    Tension and heat production were measured in frog sartorius muscles in response to small shortening ramps (releases) at high and moderate speed. Transient tension responses to fast releases (0.1 to 0.4 mm in 1 or 4 ms) were similar to the tension transients length-clamped single fibers. Tension time courses during releases at 25 mm/s were like fiber responses calculated from the first two phases of the step responses (Ford et al., 1977). We conclude that similar crossbridge transitions produce tension transients observed in whole muscles and single fibers. Heat was absorbed during rapid tension recovery after fast releases and during the later part of releases at 25 mm/s. Variation of heat absorption with release size was compared with that of crossbridge movement predicted by the Huxley-Simmons hypothesis of force generation (Huxley and Simmons, 1971). Agreement between the two supports the conclusion that heat is absorbed by the crossbridge transitions responsible for rapid tension recovery after release. The results indicate that the entropy change of these transitions is positive. PMID:3265639

  18. Transient Dysregulation of Dopamine Signaling in a Developing Drosophila Arousal Circuit Permanently Impairs Behavioral Responsiveness in Adults

    PubMed Central

    Ferguson, Lachlan; Petty, Alice; Rohrscheib, Chelsie; Troup, Michael; Kirszenblat, Leonie; Eyles, Darryl W.; van Swinderen, Bruno

    2017-01-01

    The dopamine ontogeny hypothesis for schizophrenia proposes that transient dysregulation of the dopaminergic system during brain development increases the likelihood of this disorder in adulthood. To test this hypothesis in a high-throughput animal model, we have transiently manipulated dopamine signaling in the developing fruit fly Drosophila melanogaster and examined behavioral responsiveness in adult flies. We found that either a transient increase of dopamine neuron activity or a transient decrease of dopamine receptor expression during fly brain development permanently impairs behavioral responsiveness in adults. A screen for impaired responsiveness revealed sleep-promoting neurons in the central brain as likely postsynaptic dopamine targets modulating these behavioral effects. Transient dopamine receptor knockdown during development in a restricted set of ~20 sleep-promoting neurons recapitulated the dopamine ontogeny phenotype, by permanently reducing responsiveness in adult animals. This suggests that disorders involving impaired behavioral responsiveness might result from defective ontogeny of sleep/wake circuits. PMID:28243212

  19. Transient Eddy Current Response Due to a Subsurface Crack in a Conductive Plate

    SciTech Connect

    Fu, Fangwei

    2006-01-01

    Eddy current nondestructive evaluation (NDE) is usually carried out by exciting a time harmonic field using an inductive probe. However, a viable alternative is to use transient eddy current NDE in which a current pulse in a driver coil produces a transient .eld in a conductor that decays at a rate dependent on the conductivity and the permeability of the material and the coil configuration. By using transient eddy current, it is possible to estimate the properties of the conductive medium and to locate and size potential .aws from the measured probe response. The fundamental study described in this dissertation seeks to establish a theoretical understanding of the transient eddy current NDE. Compared with the Fourier transform method, the derived analytical formulations are more convenient when the transient eddy current response within a narrow time range is evaluated. The theoretical analysis provides a valuable tool to study the effect of layer thickness, location of defect, crack opening as well as the optimization of probe design. Analytical expressions have been developed to evaluate the transient response due to eddy currents in a conductive plate based on two asymptotic series. One series converges rapidly for a short time regime and the other for a long time regime and both of them agree with the results calculated by fast Fourier transform over all the times considered. The idea of asymptotic expansion is further applied to determine the induced electromotive force (EMF) in a pick-up coil due to eddy currents in a cylindrical rod. Starting from frequency domain representation, a quasi-static time domain dyadic Green's function for an electric source in a conductive plate has been derived. The resulting expression has three parts; a free space term, multiple image terms and partial reflection terms. The dyadic Green's function serves as the kernel of an electric field integral equation which defines the interaction of an ideal crack with the transient

  20. Transient deflection response in microcantilever array integrated with polydimethylsiloxane (PDMS) microfluidics.

    PubMed

    Anderson, Ryan R; Hu, Weisheng; Noh, Jong Wook; Dahlquist, William C; Ness, Stanley J; Gustafson, Timothy M; Richards, Danny C; Kim, Seunghyun; Mazzeo, Brian A; Woolley, Adam T; Nordin, Gregory P

    2011-06-21

    We report the integration of a nanomechanical sensor consisting of 16 silicon microcantilevers with polydimethylsiloxane (PDMS) microfluidics. For microcantilevers positioned near the bottom of a microfluidic flow channel, a transient differential analyte concentration for the top versus bottom surface of each microcantilever is created when an analyte-bearing fluid is introduced into the flow channel (which is initially filled with a non-analyte containing solution). We use this effect to characterize a bare (nonfunctionalized) microcantilever array in which the microcantilevers are simultaneously read out with our recently developed high sensitivity in-plane photonic transduction method. We first examine the case of non-specific binding of bovine serum albumin (BSA) to silicon. The average maximum transient microcantilever deflection in the array is -1.6 nm, which corresponds to a differential surface stress of only -0.23 mN m(-1). This is in excellent agreement with the maximum differential surface stress calculated based on a modified rate equation in conjunction with finite element simulation. Following BSA adsorption, buffer solutions with different pH are introduced to further study microcantilever array transient response. Deflections of 20-100 nm are observed (2-14 mN m(-1) differential surface stress). At a flow rate of 5 μL min(-1), the average measured temporal width (FWHM) of the transient response is 5.3 s for BSA non-specific binding and 0.74 s for pH changes.

  1. Transient responses of phosphoric acid fuel cell power plant system. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lu, Cheng-Yi

    1983-01-01

    An analytical and computerized study of the steady state and transient response of a phosphoric acid fuel cell (PAFC) system was completed. Parametric studies and sensitivity analyses of the PAFC system's operation were accomplished. Four non-linear dynamic models of the fuel cell stack, reformer, shift converters, and heat exchangers were developed based on nonhomogeneous non-linear partial differential equations, which include the material, component, energy balance, and electrochemical kinetic features. Due to a lack of experimental data for the dynamic response of the components only the steady state results were compared with data from other sources, indicating reasonably good agreement. A steady state simulation of the entire system was developed using, nonlinear ordinary differential equations. The finite difference method and trial-and-error procedures were used to obtain a solution. Using the model, a PAFC system, that was developed under NASA Grant, NCC3-17, was improved through the optimization of the heat exchanger network. Three types of cooling configurations for cell plates were evaluated to obtain the best current density and temperature distributions. The steady state solutions were used as the initial conditions in the dynamic model. The transient response of a simplified PAFC system, which included all of the major components, subjected to a load change was obtained. Due to the length of the computation time for the transient response calculations, analysis on a real-time computer was not possible. A simulation of the real-time calculations was developed on a batch type computer. The transient response characteristics are needed for the optimization of the design and control of the whole PAFC system. All of the models, procedures and simulations were programmed in Fortran and run on IBM 370 computers at Cleveland State University and the NASA Lewis Research Center.

  2. Spatial variation in transient water table responses: Differences between an upper and lower hillslope zone

    USGS Publications Warehouse

    Haught, D.R.W.; Van Meerveld, H. J.

    2011-01-01

    To better understand storage-runoff dynamics, transient groundwater responses were examined in one of the steep watersheds in British Columbia's coastal mountains. Streamflow and piezometric data were collected for 1year to determine the spatial and temporal relations between transient groundwater levels and discharge. Correlations between piezometer responses and lag-time analysis were used to identify and better understand runoff generation mechanisms in this watershed. Results showed a large spatial and temporal variation in transient water table dynamics and indicated that two distinct zones existed: a lower hillslope zone and an upslope zone. Each zone was characterized by very different water table responses. The upper hillslope was disconnected from the stream for the majority of time, suggesting that during most events, it does not directly contribute to streamflow. Piezometers in the lower hillslope zone showed hydrologically limited responses, suggesting rapid subsurface flow, likely through the many macropores and soil pipes. The lag time between peak streamflow and peak groundwater level decreased with increasing antecedent moisture conditions and was more variable for piezometers further away from the stream than for piezometers close to the stream. The study results indicate that a single storage-runoff model is not appropriate for this steep watershed and that a two- or three-compartment model would be more suitable. ?? 2011 John Wiley & Sons, Ltd.

  3. Transient brain responses predict the temporal dynamics of sound detection in humans.

    PubMed

    Mäkinen, Ville; May, Patrick; Tiitinen, Hannu

    2004-02-01

    The neural events leading up to the conscious experience of stimulus events have remained elusive. Here we describe stimulation conditions under which activation in human auditory cortex can be used to predict the temporal dynamics of behavioral sound detection. Subjects were presented with auditory stimuli whose energy smoothly increased from a silent to a clearly audible level over either 1, 1.5, or 2 s. Magnetoencephalographic (MEG) recordings were carried out in the passive and active recording conditions. In the active condition, the subjects were instructed to attend to the auditory stimuli and to press a response key when these became audible. In both conditions, the stimuli elicited a prominent transient response whose emergence is unexplainable by changes in stimulus intensity alone. This transient response was larger in amplitude over the right hemisphere and in the active condition. Importantly, behavioral sound detection followed this brain activation with a constant delay of 180 ms, and further the latency variations of the brain response were directly carried over to behavioral reaction times. Thus, noninvasively measured transient events in the human auditory cortex can be used to predict accurately the temporal course of sound detection and may therefore turn out to be useful in clinical settings.

  4. Permeability-thickness determination from transient production response at the southeast geysers

    SciTech Connect

    Faulder, D.D.

    1996-08-01

    The Fetkovich production decline curve analysis method was extended for application to vapor-dominated geothermal reservoirs for the purpose of estimating the permeability-thickness product (kh) from the transient production response. The analytic dimensionless terms for pressure, production rate, decline rate, and decline time were derived for saturated steam using the real gas potential and customary geothermal production units of pounds-mass per hour. The derived terms were numerically validating using ``Geysers-line`` reservoir properties at initial water saturation of 0 and at permeabilities of 1, 10, and 100 mD. The production data for 48 wells in the Southeast Geysers were analyzed and the permeability-thickness products determined from the transient production response using the Fetkovich production decline type curve. The kh results were in very good agreement with the published range at the Southeast Geysers and show regions of high permeability-thickness.

  5. Local-Global Interactions in the Transient Response of Lattice-Truss Plates.

    DTIC Science & Technology

    1984-08-01

    plate model subjected to an initial out-of-plane impulse at the lower left corner. The color scale at the right of each frame represents variations of...Fiur 4. RepneapeLoain (Core ~ ~ ~ \\ and uppe sufc ebr emvdfrcaiy 23 TETRA 11 - Tranwlezt nleporave fLvtorvy 0.003 - Mrst Uccde Ix3ltial Impulse ...vidual lattice members dynamic characteristics influence the transient response charac- teristics. When the lattice members are modeled as bars. the

  6. Imaging the cellular response to transient shear stress using time-resolved digital holography

    NASA Astrophysics Data System (ADS)

    Arita, Yoshihiko; Antkowiak, Maciej; Gunn-Moore, Frank; Dholakia, Kishan

    2014-02-01

    Shear stress has been recognized as one of the biophysical methods by which to permeabilize plasma membranes of cells. In particular, high pressure transient hydrodynamic flows created by laser-induced cavitation have been shown to lead to the uptake of fluorophores and plasmid DNA. While the mechanism and dynamics of cavitation have been extensively studied using a variety of time-resolved imaging techniques, the cellular response to the cavitation bubble and cavitation induced transient hydrodynamic flows has never been shown in detail. We use time-resolved quantitative phase microscopy to study cellular response to laser-induced cavitation bubbles. Laser-induced breakdown of an optically trapped polystyrene nanoparticle (500nm in diameter) irradiated with a single nanosecond laser pulse at 532nm creates transient shear stress to surrounding cells without causing cell lysis. A bi-directional transient displacement of cytoplasm is observed during expansion and collapse of the cavitation bubble. In some cases, cell deformation is only observable at the microsecond time scale without any permanent change in cell shape or optical thickness. On a time scale of seconds, the cellular response to shear stress and cytoplasm deformation typically leads to retraction of the cellular edge most exposed to the flow, rounding of the cell body and, in some cases, loss of cellular dry mass. These results give a new insight into the cellular response to laser-induced shear stress and related plasma membrane permeabilization. This study also demonstrates that laser-induced breakdown of an optically trapped nanoparticle offers localized cavitation (70 μm in diameter), which interacts with a single cell.

  7. The TOPAZ II space reactor response under accident conditions

    SciTech Connect

    Voss, S.S.

    1993-12-31

    The TOPAZ II is a single-cell thermionic space reactor power system developed by the Russians during the period of time from {approximately}1969 to 1989. The TOPAZ II has never been flight demonstrated, but the system was extensively tested on the ground. As part of the development and test program, the response of the TOPAZ II under accident conditions was analyzed and characterized. The US TOPAZ II team has been working closely with the Russian specialists to understand the TOPAZ II system, its operational characteristics, and its response under potential accident conditions. The purpose of the technical exchange is to enable a potential launch of a TOPAZ II by the US. The information is required to integrate the system with a US spacecraft and to support the safety review process. The purpose of this paper is to provide a brief overview of the system and its response under actual and postulated accident conditions.

  8. Estimation of the transient response of a tuned, fractionally damped elastomeric isolator

    NASA Astrophysics Data System (ADS)

    Fredette, Luke; Singh, Rajendra

    2016-11-01

    This article addresses the frequency dependent properties of elastomeric vibration isolators in the context of lumped parameter models with fractional damping elements. A mass is placed between two fractional calculus Kelvin-Voigt elements to develop a minimal order system for the example case of a conventional elastomeric bushing typical of automotive suspension systems. Model parameters are acquired from measured dynamic stiffness spectra and a finite element model. The minimal order system model accurately predicts dynamic stiffness in both broadband resonant behavior as well as the lower-frequency regime that is controlled by damping. For transient response analysis, an inverse Laplace transform of the dynamic stiffness spectrum is taken via the Residue Theorem. Since the fractional calculus based solution is given in terms of problematic integrals, a new time-frequency domain estimation technique is proposed which approximates time-domain responses for a class of transient excitation functions. The approximation error is quantified and found to be reasonably small, and tractable closed-form transient response functions are provided along with a discussion of numerical issues.

  9. Three-dimensional numerical modeling of full-space transient electromagnetic responses of water in goaf

    NASA Astrophysics Data System (ADS)

    Chang, Jiang-Hao; Yu, Jing-Cun; Liu, Zhi-Xin

    2016-09-01

    The full-space transient electromagnetic response of water-filled goaves in coal mines were numerically modeled. Traditional numerical modeling methods cannot be used to simulate the underground full-space transient electromagnetic field. We used multiple transmitting loops instead of the traditional single transmitting loop to load the transmitting loop into Cartesian grids. We improved the method for calculating the z-component of the magnetic field based on the characteristics of full space. Then, we established the fullspace 3D geoelectrical model using geological data for coalmines. In addition, the transient electromagnetic responses of water-filled goaves of variable shape at different locations were simulated by using the finite-difference time-domain (FDTD) method. Moreover, we evaluated the apparent resistivity results. The numerical modeling results suggested that the resistivity differences between the coal seam and its roof and floor greatly affect the distribution of apparent resistivity, resulting in nearly circular contours with the roadway head at the center. The actual distribution of apparent resistivity for different geoelectrical models of water in goaves was consistent with the models. However, when the goaf water was located in one side, a false low-resistivity anomaly would appear on the other side owing to the full-space effect but the response was much weaker. Finally, the modeling results were subsequently confirmed by drilling, suggesting that the proposed method was effective.

  10. Mars atmospheric dynamics as simulated by the NASA AMES General Circulation Model. II - Transient baroclinic eddies

    NASA Astrophysics Data System (ADS)

    Barnes, J. R.; Pollack, J. B.; Haberle, R. M.; Leovy, C. B.; Zurek, R. W.; Lee, H.; Schaeffer, J.

    1993-02-01

    A large set of experiments performed with the NASA Ames Mars General Circulation Model is analyzed to determine the properties, structure, and dynamics of the simulated transient baroclinic eddies. There is strong transient baroclinic eddy activity in the extratropics of the Northern Hemisphere during the northern autumn, winter, and spring seasons. The eddy activity remains strong for very large dust loadings, though it shifts northward. The eastward propagating eddies are characterized by zonal wavenumbers of 1-4 and periods of about 2-10 days. The properties of the GCM baroclinic eddies in the northern extratropics are compared in detail with analogous properties inferred from Viking Lander meteorology observations.

  11. GH3-Mediated Auxin Conjugation Can Result in Either Transient or Oscillatory Transcriptional Auxin Responses.

    PubMed

    Mellor, Nathan; Bennett, Malcolm J; King, John R

    2016-02-01

    The conjugation of the phytohormone auxin to amino acids via members of the gene family GH3 is an important component in the auxin-degradation pathway in the model plant species Arabidopsis thaliana, as well as many other plant species. Since the GH3 genes are themselves up-regulated in response to auxin, providing a negative feedback on intracellular auxin levels, it is hypothesised that the GH3s have a role in auxin homoeostasis. To investigate this, we develop a mathematical model of auxin signalling and response that includes the auxin-inducible negative feedback from GH3 on the rate of auxin degradation. In addition, we include a positive feedback on the rate of auxin input via the auxin influx transporter LAX3, shown previously to be expressed in response to auxin and to have an important role during lateral root emergence. In the absence of the LAX3 positive feedback, we show that the GH3 negative feedback suffices to generate a transient transcriptional response to auxin in the shape of damped oscillations of the model system. When LAX3 positive feedback is present, sustained oscillations of the system are possible. Using steady-state analyses, we identify and discuss key parameters affecting the oscillatory behaviour of the model. The transient peak of auxin and subsequent transcriptional response caused by the up-regulation of GH3 represents a possible protective homoeostasis mechanism that may be used by plant cells in response to excess auxin.

  12. Transient response of the calcium homeostatic system of the conscious pig to bolus calcium injections.

    PubMed

    Járos, G G; Maier, H; Podzuweit, T; von Gülich, M; Schindler, J G

    1982-07-01

    Calcium injection in the pig elicits a fast transient response which reinstates the calcium concentration to within normal limits between 30 and 40 min after injection. Although the fate of the calcium that disappeared is not known, the present experiments eliminate the kidneys and the bone remodeling cells as the main short-term regulators. The fast response is independent of parathyroid hormone but is greatly dependent of calcitonin. Further experiments are being performed to discover the nature and site of the regulating mechanisms.

  13. Flow Driven by an Archimedean Helical Permanent Magnetic Field. Part II: Transient and Modulated Flow Behaviors

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Wang, Xiaodong; Fautrelle, Yves; Etay, Jacqueline; Na, Xianzhao; Baltaretu, Florin

    2016-12-01

    The present study considers the transient and modulated flow behaviors of liquid metal driven by a helical permanent magnetic field. The transient process, in which the fluid at rest experiences an increase in the angular velocity, is observed both in secondary and global axial flow with duration time less than 1 second. The flow fields are measured quantitatively to reveal the evolution of the transient flow, and the transient process is due to the variation of the electromagnetic force. Besides, the modulated flow behaviors of global axial flow, which is significantly different from that of secondary flow, is expected to avoid flow-induced macrosegregation in solidification process if the modulated time is suitable because its direction reversed periodically with the modulated helical stirrer. In addition, an optimal modulation frequency, under which the magnetic field could efficiently stir the solute at the solidification front, exists both in secondary and global axial flow (0.1 Hz and 0.625 Hz, respectively). Future investigations will focus on additional metallic alloy solidification experiments.

  14. ORIENTATION CLASSES FOR IN-MIGRANT TRANSIENT CHILDREN. A FIRST REPORT, PART II.

    ERIC Educational Resources Information Center

    PONDER, EDDIE G.; AND OTHERS

    A 3-YEAR STUDY OF THE ORIENTATION OF IMMIGRANT TRANSIENT CHILDREN WAS INITIATED IN SEPTEMBER, 1960. PART ONE GIVES AN OVERVIEW OF THE PROJECT FOR THE SCHOOL YEAR 1961-61. IT REVIEWS THE ORGANIZATION OF THE ORIENTATION CLASSES, THE INSERVICE PROGRAM, COMMUNITY ORIENTATION, AND REPORTS OF SPECIAL SERVICES GIVEN TO THE PROJECT CLASSES. PART TWO…

  15. Sustained Inhibition of Proliferative Response After Transient FGF Stimulation Is Mediated by Interleukin 1 Signaling.

    PubMed

    Poole, Ashleigh; Kacer, Doreen; Cooper, Emily; Tarantini, Francesca; Prudovsky, Igor

    2016-03-01

    Transient FGF stimulation of various cell types results in FGF memory--a sustained blockage of efficient proliferative response to FGF and other growth factors. FGF memory establishment requires HDAC activity, indicating its epigenetic character. FGF treatment stimulates proinflammatory NFκB signaling, which is also critical for FGF memory formation. The search for FGF-induced mediators of FGF memory revealed that FGF stimulates HDAC-dependent expression of the inflammatory cytokine IL1α. Similarly to FGF, transient cell treatment with recombinant IL1α inhibits the proliferative response to further FGF and EGF stimulation, but does not prevent FGF receptor-mediated signaling. Interestingly, like cells pretreated with FGF1, cells pretreated with IL1α exhibit enhanced restructuring of actin cytoskeleton and increased migration in response to FGF stimulation. IRAP, a specific inhibitor of IL 1 receptor, and a neutralizing anti-IL1α antibody prevent the formation of FGF memory and rescue an efficient proliferative response to FGF restimulation. A similar effect results following treatment with the anti-inflammatory agents aspirin and dexamethasone. Thus, FGF memory is mediated by proinflammatory IL1 signaling. It may play a role in the limitation of proliferative response to tissue damage and prevention of wound-induced hyperplasia.

  16. The transient response of land and ocean precipitation in changing climates

    NASA Astrophysics Data System (ADS)

    Mcinerney, D. J.; Moyer, E. J.

    2011-12-01

    Although much attention in climate modeling is focused on fine-scale regional predictions, we suggest that diagnostics based on near-global characteristics of climate models provide insight into the underlying physics that differentiates general circulation models (GCMs) and in understanding the robustness of climate forecasts in conditions of changing radiative forcing. We show that certain aspects of the response of precipitation in transient climates are robust across models, including models with very different convective parameterization schemes, suggesting that they reflect some fundamental aspect of the climate system. Climate models are in broad agreement that the hydrological cycle is enhanced in conditions of higher atmospheric CO2 concentration, i.e. that global precipitation increases with surface temperature, but recent studies have shown that in transient climates the change in precipitation per warming is suppressed relative to its equilibrium value (ΔP/ΔT<ΔPeq/ΔTeq). This suppression, which we term the "disequilibrium precipitation response", manifests within days to months of a change in radiative forcing and has been cited as important for impacts assessments. We show that the disequilibrium precipitation response occurs over the ocean but is not present over land (and so has minimal effect on human welfare). This distinction is robust across 12 of 13 climate models in the CMIP3 archive. These findings are consistent with the previously proposed mechanism for this effect: that ocean heat burial reduces transient warming at the ocean surface relative to the mid-troposphere, increasing atmospheric stability and thereby inhibiting convection. This lapse rate change appears to be a common feature of climate models, although the size of the disequilibrium precipitation effect varies between them. We show that the most common representation of the disequilibrium precipitation response in the literature can be reduced to a simple statement that

  17. Temporal relaxation of nonequilibrium in Y-Ba-Cu-O measured from transient photoimpedance response

    SciTech Connect

    Bluzer, N. )

    1991-11-01

    Nonequilibrium in Y-Ba-Cu-O thin films biased with a dc current is photoinduced by exposure to 300-fsec 2-eV laser pulses. The photoinduced nonequilibrium transients were measured in the superconducting, transition, and normal states occurring between 7 and 200 K. The photoabsorption produced temporal changes in the sample's impedance, which manifest themselves as transient voltage signals occurring across the samples during the nonequilibrium's relaxation process. At and above {ital T}{sub {ital c}}, the observed photoresponse is thermal. Below {ital T}{sub {ital c}}, a quantum response is obtained corresponding to changes in the Cooper-pair populations. In the zero-resistance superconducting state, a positive signal corresponds to quasiparticle generation and a negative signal corresponds to quasiparticle recombination.

  18. Response-coefficient method for heat-conduction transients with time-dependent inputs

    NASA Technical Reports Server (NTRS)

    Ceylan, Tamer

    1993-01-01

    A theoretical overview of the response coefficient method for heat conduction transients with time-dependent input forcing functions is presented with a number of illustrative applications. The method may be the most convenient and economical if the same problem is to be solved many times with different input-time histories or if the solution time is relatively long. The method is applicable to a wide variety of problems, including irregular geometries, position-dependent boundary conditions, position-dependent physical properties, and nonperiodic irregular input histories. Nonuniform internal energy generation rates within the structure can also be handled by the method. The area of interest is long-time solutions, in which initial condition is unimportant, and not the early transient period. The method can be applied to one dimensional problems in cartesian, cylindrical, and spherical coordinates as well as to two dimensional problems in cartesian and cylindrical coordinates.

  19. The transient roll moment response due to forebody tangential blowing at high angles of attack

    NASA Astrophysics Data System (ADS)

    Chow, Jonathan Kwokching

    The sustained ability for controlled flight at high angles of attack is desirable for future aircraft. For combat aircraft, enhancing maneuverability is important to increasing its survivability. For future supersonic commercial aircraft, an increase in lift at high angles of attack leads to improved performance during take-offs and landing, and a reduction in noise pollution. However, nonlinear and unsteady phenomena, such as flow separation and vortex shedding dominate the aerodynamics in the high angle of attack regime. These phenomena cause the onset of lateral loads and decrease the effectiveness of conventional control surfaces. For conventional aircraft, controlled flight at high angle of attack is difficult or unfeasible without augmented means of control and a good understanding of their impact on vehicle characteristics and dynamics. The injection of thin sheets of air tangentially to the forebody of the vehicle has been found to be an extremely promising method for augmenting the control of a flight vehicle at high angles of attack. Forebody Tangential Blowing (FTB) allows the flow structure to be altered in a rational manner and increase the controllability of the vehicle under these flight conditions. The feasibility of using FTB to control the roll-yaw motion of flight vehicles has been demonstrated. Existing knowledge of FTB's nonlinear impact on the aerodynamic moment responses is limited. Currently available dynamic models predict the general trends in the behavior but do not capture important transient effects that dominate the responses when small amounts of blowing is used. These transients can be large in comparison to the steady-state values. This thesis summarizes the experimental and theoretical results of an investigation into the transient effects of Forebody Tangential Blowing. The relationship between the aerodynamic roll moment, vortical flowfield, and blowing strength is examined to obtain a fundamental understanding of the physics of

  20. Transient responses of an axially accelerating viscoelastic string constituted by a fractional differentiation law

    NASA Astrophysics Data System (ADS)

    Chen, Li-Qun; Zhao, Wei-Jia; Zu, Jean W.

    2004-12-01

    This paper deals with the transverse vibration of an initially stressed moving viscoelastic string obeying a fractional differentiation constitutive law. The governing equation is derived from Newtonian second law of motion, and reduced to a set of non-linear differential-integral equations based on Galerkin's truncation. A numerical approach is proposed to solve numerically the differential-integral equation through developing an approximate expression of the fractional derivatives involved. Some numerical examples are presented to highlight the effects of viscoelastic parameters and frequencies of parametric excitations on the transient responses of the axially moving string.

  1. Transient Response of Shells of Revolution by Direct Integration and Modal Superposition Methods

    NASA Technical Reports Server (NTRS)

    Stephens, W. B.; Adelman, H. M.

    1974-01-01

    The results of an analytical effort to obtain and evaluate transient response data for a cylindrical and a conical shell by use of two different approaches: direct integration and modal superposition are described. The inclusion of nonlinear terms is more important than the inclusion of secondary linear effects (transverse shear deformation and rotary inertia) although there are thin-shell structures where these secondary effects are important. The advantages of the direct integration approach are that geometric nonlinear and secondary effects are easy to include and high-frequency response may be calculated. In comparison to the modal superposition technique the computer storage requirements are smaller. The advantages of the modal superposition approach are that the solution is independent of the previous time history and that once the modal data are obtained, the response for repeated cases may be efficiently computed. Also, any admissible set of initial conditions can be applied.

  2. Transient response of structures with uncertain properties to nonlinear shock loading

    NASA Astrophysics Data System (ADS)

    Caresta, Mauro; Langley, Robin S.; Woodhouse, Jim

    2013-10-01

    A method is presented to predict the transient response of a structure at the driving point following an impact or a shock loading. The displacement and the contact force are calculated solving the discrete convolution between the impulse response and the contact force itself, expressed in terms of a nonlinear Hertzian contact stiffness. Application of random point process theory allows the calculation of the impulse response function from knowledge of the modal density and the geometric characteristics of the structure only. The theory is applied to a wide range of structures and results are experimentally verified for the case of a rigid object hitting a beam, a plate, a thin and a thick cylinder and for the impact between two cylinders. The modal density of the flexural modes for a thick slender cylinder is derived analytically. Good agreement is found between experimental, simulated and published results, showing the reliability of the method for a wide range of situations including impacts and pyroshock applications.

  3. Preliminary Transient Performance Data on the J73 Turbojet Engine. II - Altitude, 35,000 Feet

    NASA Technical Reports Server (NTRS)

    Lubick, Robert J.; Sobolewski, Adam E.

    1953-01-01

    A program was undertaken to determine the J73 turbojet engine compressor stall and surge characteristics and combustor blow-out limits encountered during transient engine operation. Data were obtained in the form of oscillograph traces showing the time history of several engine performance parameters with changes in engine fuel flow. The data presented in this report are for step changes in fuel flow at an altitude of 35,000 feet, at flight Mach numbers of 0.3, 0.8, and 1.2, and at several engine-inlet temperatures,

  4. The transient dermal exposure II: post-exposure absorption and evaporation of volatile compounds.

    PubMed

    Frasch, H Frederick; Bunge, Annette L

    2015-04-01

    The transient dermal exposure is one where the skin is exposed to chemical for a finite duration, after which the chemical is removed and no residue remains on the skin's surface. Chemical within the skin at the end of the exposure period can still enter the systemic circulation. If it has some volatility, a portion of it will evaporate from the surface before it has a chance to be absorbed by the body. The fate of this post-exposure "skin depot" is the focus of this theoretical study. Laplace domain solutions for concentration distribution, flux, and cumulative mass absorption and evaporation are presented, and time domain results are obtained through numerical inversion. The Final Value Theorem is applied to obtain the analytical solutions for the total fractional absorption by the body and evaporation from skin at infinite time following a transient exposure. The solutions depend on two dimensionless variables: χ, the ratio of evaporation rate to steady-state dermal permeation rate; and the ratio of exposure time to membrane lag time. Simple closed form algebraic equations are presented that closely approximate the complete analytical solutions. Applications of the theory to the dermal risk assessment of pharmaceutical, occupational, and environmental exposures are presented for four example chemicals.

  5. Studies of Accreting Neutron Stars with RXTE Cycle 4 Observations: II: Too Observations of Transient LMXBs

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    2002-01-01

    NASA Grant NAG 5-9045 provided funds for the research project 'TOO Observations of Transient LMxBs' approved under the Rossi X-ray Timing Explorer (RXTE) Guest Observer Program Cycle 4 and funded under the 1999 NASA Astrophysics Data Program. The principal investigator of the observing time proposal was Dr. M. Mendez (U. of Amsterdam). The grant was funded for one year beginning 3/1/2000. The original proposal was submitted by Prof. Jan van Paradijs, who passed away in 1999 before the funds were distributed. Prof. William S. Pauesas administered the grant during the period of performance. In spite of a wealth of observational data on the kHz QPO in low-mass X-ray binaries (LMXBs), the interpretation of this phenomenon is currently uncertain because the pairs of kHz QPO peaks and the oscillations seen in some Type I X-ray bursts are almost, but not quite, connected by a simple beat frequency relation. The proposal was intended to contribute to a solution to this confusion by making RXTE target-of-opportunity observations of two transient LMXBs, Aql X-1 and 4U 1608-52, if the sources became sufficiently bright.

  6. Active landsliding and landscape denudation in response to transient tectonic uplift, Northern California.

    NASA Astrophysics Data System (ADS)

    Bennett, G. L.; Roering, J. J.; Miller, S. R.; Kirby, E.; Schmidt, D. A.

    2014-12-01

    The northern Californian Coast ranges present a unique area to study landscape response to transient tectonic uplift. Studies have shown that an increase in uplift may be balanced by the rate of landsliding in settings of steady uplift. However, the landsliding response to transient tectonic uplift remains to be elucidated. The Californian Coast ranges are shaped by the northward migration of the Mendocino Triple Junction (MTJ), which geodynamic modeling suggests produces a transient double-humped uplift field. A major research question is whether we can detect a signature of this transient tectonic uplift in landslide activity and document how the channel network communicates this signal to hillslopes. Using air photos and Worldview imagery, we manually mapped more than 2000 earthflows and debris slides in the Eel and surrounding catchments that span the ~400 km-long region. The velocities of active earthflows were estimated by visually tracking features between images spanning 1993 to 2013. We mapped channel steepness from 10m NED DEMs in Topotoolbox 2 and developed a new tool to automatically define knickpoints along the channel network. Earthflows occur almost exclusively in a band of Franciscan mélange oriented along the MTJ transect whilst debris slides are more evenly distributed by lithology. Both earthflows and debris slides are clustered in the Eel catchment around the proposed uplift peaks and are largely absent outside of these zones. Within these areas of high landslide densities, we observe peaks in active earthflows adjacent to peaks in dormant earthflows to the south, suggesting that the signature of earthflow activity remains for a period of time once the uplift peak has passed. Landslide density, mean landslide area, and earthflow velocity all increase rapidly above threshold values of channel steepness and local relief. In the Eel catchment, where the zone of rapid uplift is commencing, landslides, particularly earth flows, are concentrated

  7. Thermal-hydraulic-structural behavior of the EBR-II IHX for overpower transients

    SciTech Connect

    Mohr, D.; Chang, L.K.; Lee, M.J.; Feldman, E.E.

    1982-01-01

    A detailed study has been made of the effects of the Operational Reliability Testing (ORT) program on major plant components of the Experimental Breeder Reactor No. II (EBR-II). This paper describes the integrated thermal-hydraulic-structural analyses conducted for the intermediate heat exchanger (IHX) with the aid of the NATDEMO, THTB, and ANSYS codes. An extensive analysis revealed the stress limiting area to be the junction between the upper head and upper tube sheet. The analyses indicate, however, that the EBR-II IHX, the major plant component most affected by the ORT program, will be able to withstand the thermal stress and accumulated fatigue damage during the lifetime of the plant including the ORT program.

  8. Transient freezing behavior in photophobic responses of Euglena gracilis investigated in a microfluidic device.

    PubMed

    Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Maeda, Mizuo

    2014-10-01

    We found that the transient freezing behavior in photophobic responses of Euglena gracilis is a good indicator of the metabolic status of the cells. The transient blue light photophobic responses of E. gracilis cells were investigated on-chip using a new measurement, 'trace momentum' (TM), to evaluate their swimming activity quantitatively in real time. When blue light of intensity >30 mW cm(-2) was repeatedly switched on and off, a large negative spike in the TM was observed at the onset of the 'blue-light-off' phase. Single-cell trace analysis at a blue light intensity of 40 mW cm(-2) showed that 48% (on average, n = 15) of tumbling Euglena cells ceased activity ('freezing') for 2-30 s at the onset of blue-light-off before commencing forward motion in a straight line (termed 'straightforward swimming'), while 45% smoothly commenced straightforward swimming without delay. The proportion of freezing Euglena cells depended on the blue light intensity (only 20% at 20 mW cm(-2)). When the cells were stimulated by four blue light pulses at the higher intensity, without pre-exposure, the transient freezing behavior was more prominent but, on repeating the stimuli after an 80 min interval in red light, the same cells did not freeze. This shows that the metabolism of the cells had changed to anti-freezing during the interval. The relationship between the interval time with/without light irradiation and the blue light adaptation was elucidated experimentally. The origin of the freezing behavior is considered to be a shortage of a metabolic substance that promotes smooth switching of flagellum movement from in situ rotation mode to a straightforward swimming mode.

  9. The Transient Circulation Response to Radiative Forcings and Sea Surface Warming

    SciTech Connect

    Staten, Paul; Reichler, Thomas; Lu, Jian

    2014-08-27

    Tropospheric circulation shifts have strong potential to impact surface climate. But the magnitude of these shifts in a changing climate, and the attending regional hydrological changes, are difficult to project. Part of this difficulty arises from our lack of understanding of the physical mechanisms behind the circulation shifts themselves. In order to better delineate circulation shifts and their respective causes, we decompose the circulation response into (1) the "direct" response to radiative forcings themselves, and (2) the "indirect" response to changing sea surface temperatures. Using ensembles of 90-day climate model simulations with immediate switch-on forcings, including perturbed greenhouse gas concentrations, stratospheric ozone concentrations, and sea surface temperatures, we document the direct and indirect transient responses of the zonal mean general circulation, and investigate the roles of previously proposed mechanisms in shifting the midlatitude jet. We find that both the direct and indirect wind responses often begin in the lower stratosphere. Changes in midlatitude eddies are ubiquitous and synchronous with the midlatitude zonal wind response. Shifts in the critical latitude of wave absorption on either flank of the jet are not indicted as primary factors for the poleward shifting jet, although we see some evidence for increasing equatorward wave reflection over the southern hemisphere in response to sea surface warming. Mechanisms for the northern hemisphere jet shift are less clear.

  10. Mechanism of Formation of Copper(II) Chloro Complexes Revealed by Transient Absorption Spectroscopy and DFT/TDDFT Calculations.

    PubMed

    Mereshchenko, Andrey S; Olshin, Pavel K; Karabaeva, Kanykey E; Panov, Maxim S; Wilson, R Marshall; Kochemirovsky, Vladimir A; Skripkin, Mikhail Yu; Tveryanovich, Yury S; Tarnovsky, Alexander N

    2015-07-16

    Copper(II) complexes are extremely labile with typical ligand exchange rate constants on the order of 10(6)-10(9) M(-1) s(-1). As a result, it is often difficult to identify the actual formation mechanism of these complexes. In this work, using UV-vis transient absorption when probing in a broad time range (20 ps to 8 μs) in conjunction with DFT/TDDFT calculations, we studied the dynamics and underlying reaction mechanisms of the formation of extremely labile copper(II) CuCl4(2-) chloro complexes from copper(II) CuCl3(-) trichloro complexes and chloride ions. These two species, produced via photochemical dissociation of CuCl4(2-) upon 420 nm excitation into the ligand-to-metal-charge-transfer electronic state, are found to recombine into parent complexes with bimolecular rate constants of (9.0 ± 0.1) × 10(7) and (5.3 ± 0.4) × 10(8) M(-1) s(-1) in acetonitrile and dichloromethane, respectively. In dichloromethane, recombination occurs via a simple one-step addition. In acetonitrile, where [CuCl3](-) reacts with the solvent to form a [CuCl3CH3CN](-) complex in less than 20 ps, recombination takes place via ligand exchange described by the associative interchange mechanism that involves a [CuCl4CH3CN](2-) intermediate. In both solvents, the recombination reaction is potential energy controlled.

  11. ONE-DIMENSIONAL NUMERICAL ANALYSIS OF THE TRANSIENT THERMAL RESPONSE OF MULTILAYER INSULATIVE SYSTEMS

    NASA Technical Reports Server (NTRS)

    Pittman, C. M.

    1994-01-01

    This program performs a one-dimensional numerical analysis of the transient thermal response of multi-layer insulative systems. The analysis can determine the temperature distribution through a system consisting of from one to four layers, one of which can be an air gap. Concentrated heat sinks at any interface can be included. The computer program based on the analysis will determine the thickness of a specified layer that will satisfy a temperature limit criterion at any point in the insulative system. The program will also automatically calculate the thickness at several points on a system and determine the total system mass. This program was developed as a tool for designing thermal protection systems for high-speed aerospace vehicles but could be adapted to many areas of industry involved in thermal insulation systems. In this package, the equations describing the transient thermal response of a system are developed. The governing differential equation for each layer and boundary condition are put in finite-difference form using a Taylor's series expansion. These equations yield an essentially tridiagonal matrix of unknown temperatures. A procedure based on Gauss' elimination method is used to solve the matrix. This program is written in FORTRAN IV for the CDC RUN compiler and has been implemented on a CDC 6000 series machine operating under SCOPE 3.0. This program requires a minimum of 44K (octal) of 60 bit words of memory.

  12. Ventilatory response of goats to transient changes in CO2 and O2 during acute hypoxia.

    PubMed

    Smith, C A; Kellogg, R H

    1975-07-01

    The authors assessed the relative sensitivity of the peripheral chemoreceptors of 4 goats to a transient decrease in inspired CO2 using a 2-breath test. This test provides a steady-state background of hypoxia and hypercapnia and then, for 2 breaths, an equally hypoxic gas mixture containing no CO2. Another type of 2-breath test, providing 2 breaths of a hyperoxic gas mixture against a background of hypoxia, was used to establish the time course of a response known to come from peripheral chemoreceptors. Seven human subjects were studied in a similar fashion to establish the validity of the procedure. Except for 2 responses, the author's human data agree with those reported previously by others. All 4 goats resembled man in responding to removal of hypoxia with a significant decrease in ventilation, but 3 of the 4 goats, unlike man, showed no significant decrease in ventilation when CO2 was removed. The authors conclude that the peripheral chemoreceptors of goats are commonly insensitive to transient changes in inspired CO2 during acute hypoxia.

  13. An Analytical Solution for Transient Thermal Response of an Insulated Structure

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    2012-01-01

    An analytical solution was derived for the transient response of an insulated aerospace vehicle structure subjected to a simplified heat pulse. This simplified problem approximates the thermal response of a thermal protection system of an atmospheric entry vehicle. The exact analytical solution is solely a function of two non-dimensional parameters. A simpler function of these two parameters was developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Using these techniques, the maximum structural temperature rise was calculated using the analytical solutions and shown to typically agree with finite element simulations within 10 to 20 percent over the relevant range of parameters studied.

  14. Thermomechanical Response of a Gas to Spatially Resolved Power Deposition Transients

    NASA Astrophysics Data System (ADS)

    Kassoy, David R.

    2015-11-01

    Liquid propellant rocket engine (LPRE) instability is characterized by growing pressure oscillations that affect the integrity and performance of the system. Modeling and prediction have been topics of intense interest to designers for more than 60 years. LPRE combustion provides a wonderful opportunity to employ thermomechanical concepts and mathematical methodologies to quantify the response of combustion chamber gases to spatially distributed, transient thermal energy deposition. Nondimensional Euler equations, including a power deposition term in the energy equation are used to identify crucial parameters, time and length scales, as well as levels of energy deposition, relevant to LPRE performance. The objective is to provide first principles explanations of physical phenomena responsible for mechanical disturbances observed in operating LPRE's.

  15. Two Analyte Calibration From The Transient Response Of Potentiometric Sensors Employed With The SIA Technique

    SciTech Connect

    Cartas, Raul; Mimendia, Aitor; Valle, Manel del; Legin, Andrey

    2009-05-23

    Calibration models for multi-analyte electronic tongues have been commonly built using a set of sensors, at least one per analyte under study. Complex signals recorded with these systems are formed by the sensors' responses to the analytes of interest plus interferents, from which a multivariate response model is then developed. This work describes a data treatment method for the simultaneous quantification of two species in solution employing the signal from a single sensor. The approach used here takes advantage of the complex information recorded with one electrode's transient after insertion of sample for building the calibration models for both analytes. The departure information from the electrode was firstly processed by discrete wavelet for transforming the signals to extract useful information and reduce its length, and then by artificial neural networks for fitting a model. Two different potentiometric sensors were used as study case for simultaneously corroborating the effectiveness of the approach.

  16. Microflowmeter-tension disc infiltrometer: Part II - Hydraulic properties estimation from transient infiltration rate analysis

    NASA Astrophysics Data System (ADS)

    Moret-Fernández, David; Latorre, Borja; González-Cebollada, César

    2012-10-01

    SummaryMeasurements of soil sorptivity (S0) and hydraulic conductivity (K0) are of paramount importance for many soil-related studies involving disciplines such as agriculture, forestry and hydrology. In the last two decades, the disc infiltrometer has become a very popular instrument for estimations of soil hydraulic properties. The previous paper in this series presented a new design of disc infiltrometer that directly estimates the transient flow of infiltration rate curves. The objective of this paper is to present a simple procedure for estimating K0 and S0 from the linearisation of the transient infiltration rate curve with respect to the inverse of the square root of time (IRC). The technique was tested in the laboratory on 1D sand columns and 1D and 3D 2-mm sieved loam soil columns and validated under field conditions on three different soil surfaces. The estimated K0 and S0 were subsequently compared to the corresponding values calculated with the Vandervaere et al. (2000) technique, which calculates the soil hydraulic parameters from the linearisation of the differential cumulative infiltration curve with respect to the square root of time (DCI). The results showed that the IRC method, with more significant linearised models and higher values of the coefficient of determination, allows more accurate estimation of K0 and S0 than the DCI technique. Field experiments demonstrate that the IRC procedure also makes it possible to detect and eliminate the effect of the sand contact layer commonly used in the disc infiltrometry technique. Comparison between the measured and the modelled cumulative infiltration curves for the K0 and S0 values estimated by the DCI and IRC methods in all the 1D and 3D laboratory experiments and field measurements shows that the IRC technique allowed better fittings between measured and modelled cumulative infiltration curves, which indicates better estimations of the soil hydraulic properties.

  17. Intracranial recordings reveal transient response dynamics during information maintenance in human cerebral cortex.

    PubMed

    Noy, Niv; Bickel, Stephan; Zion-Golumbic, Elana; Harel, Michal; Golan, Tal; Davidesco, Ido; Schevon, Catherine A; McKhann, Guy M; Goodman, Robert R; Schroeder, Charles E; Mehta, Ashesh D; Malach, Rafael

    2015-10-01

    Despite an extensive body of work, it is still not clear how short term maintenance of information is implemented in the human brain. Most prior research has focused on "working memory"-typically involving the storage of a number of items, requiring the use of a phonological loop and focused attention during the delay period between encoding and retrieval. These studies largely support a model of enhanced activity in the delay interval as the central mechanism underlying working memory. However, multi-item working memory constitutes only a subset of storage phenomena that may occur during daily life. A common task in naturalistic situations is short term memory of a single item-for example, blindly reaching to a previously placed cup of coffee. Little is known about such single-item, effortless, storage in the human brain. Here, we examined the dynamics of brain responses during a single-item maintenance task, using intracranial recordings implanted for clinical purpose in patients (ECoG). Our results reveal that active electrodes were dominated by transient short latency visual and motor responses, reflected in broadband high frequency power increases in occipito-temporal, frontal, and parietal cortex. Only a very small set of electrodes showed activity during the early part of the delay period. Interestingly, no cortical site displayed a significant activation lasting to the response time. These results suggest that single item encoding is characterized by transient high frequency ECoG responses, while the maintenance of information during the delay period may be mediated by mechanisms necessitating only low-levels of neuronal activations.

  18. The KIVA-II computer program for transient multidimensional chemically reactive flows with sprays

    SciTech Connect

    Amsden, A.A.; Butler, T.D.; O'Rourke, P.J.

    1987-01-01

    Since its public release in 1985, the KIVA computer program has been utilized for the time dependent analysis of chemically reacting flows with sprays in two and three space dimensions. This paper describes some of the improvements to the original version that have been made since that time. The new code called KIVA-II is planned for public release in early 1988. KIVA-II improves the earlier version in the accuracy and efficiency of the computational procedure, the accuracy of the physics submodels, and in versatility and ease of use. Numerical improvements include the use of the ICE solution procedure in place of the acoustic subcycling method and the implementation of a quasi-second-order-accurate convection scheme. Major extensions to the physical submodels include the inclusion of an optional k-epsilon turbulence model, and several additions to the spray model. We illustrate some of the new capabilities by means of example solutions. 25 refs., 7 figs.

  19. Regional estimates of the transient climate response to cumulative CO2 emissions

    NASA Astrophysics Data System (ADS)

    Leduc, Martin; Matthews, H. Damon; de Elía, Ramón

    2016-05-01

    The Transient Climate Response to cumulative carbon Emissions (TCRE) measures the response of global temperatures to cumulative CO2 emissions. Although the TCRE is a global quantity, climate impacts manifest predominantly in response to local climate changes. Here we quantify the link between CO2 emissions and regional temperature change, showing that regional temperatures also respond approximately linearly to cumulative CO2 emissions. Using an ensemble of twelve Earth system models, we present a novel application of pattern scaling to define the regional pattern of temperature change per emission of CO2. Ensemble mean regional TCRE values range from less than 1 °C per TtC for some ocean regions, to more than 5 °C per TtC in the Arctic, with a pattern of higher values over land and at high northern latitudes. We find also that high-latitude ocean regions deviate more strongly from linearity as compared to land and lower-latitude oceans. This suggests that ice-albedo and ocean circulation feedbacks are important contributors to the overall negative deviation from linearity of the global temperature response to high levels of cumulative emissions. The strong linearity of the regional climate response over most land regions provides a robust way to quantitatively link anthropogenic CO2 emissions to local-scale climate impacts.

  20. Role of Bound Zn(II) in the CadC Cd(II)/Pb(II)/Zn(II)-Responsive Repressor

    SciTech Connect

    Kandegedara, A.; Thiyagarajan, S; Kondapalli, K; Stemmler, T; Rosen, B

    2009-01-01

    The Staphylococcus aureus plasmid pI258 cadCA operon encodes a P-type ATPase, CadA, that confers resistance to Cd(II)/Pb(II)/Zn(II). Expression is regulated by CadC, a homodimeric repressor that dissociates from the cad operator/promoter upon binding of Cd(II), Pb(II), or Zn(II). CadC is a member of the ArsR/SmtB family of metalloregulatory proteins. The crystal structure of CadC shows two types of metal binding sites, termed Site 1 and Site 2, and the homodimer has two of each. Site 1 is the physiological inducer binding site. The two Site 2 metal binding sites are formed at the dimerization interface. Site 2 is not regulatory in CadC but is regulatory in the homologue SmtB. Here the role of each site was investigated by mutagenesis. Both sites bind either Cd(II) or Zn(II). However, Site 1 has higher affinity for Cd(II) over Zn(II), and Site 2 prefers Zn(II) over Cd(II). Site 2 is not required for either derepression or dimerization. The crystal structure of the wild type with bound Zn(II) and of a mutant lacking Site 2 was compared with the SmtB structure with and without bound Zn(II). We propose that an arginine residue allows for Zn(II) regulation in SmtB and, conversely, a glycine results in a lack of regulation by Zn(II) in CadC. We propose that a glycine residue was ancestral whether the repressor binds Zn(II) at a Site 2 like CadC or has no Site 2 like the paralogous ArsR and implies that acquisition of regulatory ability in SmtB was a more recent evolutionary event.

  1. A transient response analysis of the space shuttle vehicle during liftoff

    NASA Technical Reports Server (NTRS)

    Brunty, J. A.

    1990-01-01

    A proposed transient response method is formulated for the liftoff analysis of the space shuttle vehicles. It uses a power series approximation with unknown coefficients for the interface forces between the space shuttle and mobile launch platform. This allows the equation of motion of the two structures to be solved separately with the unknown coefficients at the end of each step. These coefficients are obtained by enforcing the interface compatibility conditions between the two structures. Once the unknown coefficients are determined, the total response is computed for that time step. The method is validated by a numerical example of a cantilevered beam and by the liftoff analysis of the space shuttle vehicles. The proposed method is compared to an iterative transient response analysis method used by Martin Marietta for their space shuttle liftoff analysis. It is shown that the proposed method uses less computer time than the iterative method and does not require as small a time step for integration. The space shuttle vehicle model is reduced using two different types of component mode synthesis (CMS) methods, the Lanczos method and the Craig and Bampton CMS method. By varying the cutoff frequency in the Craig and Bampton method it was shown that the space shuttle interface loads can be computed with reasonable accuracy. Both the Lanczos CMS method and Craig and Bampton CMS method give similar results. A substantial amount of computer time is saved using the Lanczos CMS method over that of the Craig and Bampton method. However, when trying to compute a large number of Lanczos vectors, input/output computer time increased and increased the overall computer time. The application of several liftoff release mechanisms that can be adapted to the proposed method are discussed.

  2. Transient receptor potential channel A1 and noxious cold responses in rat cutaneous nociceptors.

    PubMed

    Dunham, J P; Leith, J L; Lumb, B M; Donaldson, L F

    2010-02-17

    The role of transient receptor potential channel A1 (TRPA1) in noxious cold sensation remains unclear. Some data support the hypothesis that TRPA1 is a transducer of noxious cold whilst other data contest it. In this study we investigated the role of TRPA1 in cold detection in cutaneous nociceptors in vivo using complementary experimental approaches. We used noxious withdrawal reflex electromyography, and single fibre recordings in vivo, to test the hypothesis that TRPA1-expressing primary afferents mediate noxious cold responses in anaesthetised rats. TRPV1 and TRPM8 agonists sensitise their cognate receptors to heat and cold stimuli respectively. Herein we show that the TRPA1 agonist cinnamaldehyde applied to the skin in anaesthetised rats did not sensitise noxious cold evoked hind limb withdrawal. In contrast, cinnamaldehyde did sensitise the C fibre-mediated noxious heat withdrawal, indicated by a significant drop in the withdrawal temperature. TRPA1 agonist thus sensitised the noxious reflex withdrawal to heat, but not cold. Thermal stimuli also sensitise transient receptor potential (TRP) channels to agonist. Activity evoked by capsaicin in teased primary afferent fibres showed a significant positive correlation with receptive field temperature, in both normal and Freund's complete adjuvant-induced cutaneous inflammation. Altering the temperature of the receptive field did not modulate TRPA1 agonist evoked-activity in cutaneous primary afferents, in either normal or inflamed skin. In addition, block of the TRPA1 channel with Ruthenium Red did not inhibit cold evoked activity in either cinnamaldehyde sensitive or insensitive cold responsive nociceptors. In cinnamaldehyde-sensitive-cold-sensitive afferents, although TRPA1 agonist-evoked activity was totally abolished by Ruthenium Red, cold evoked activity was unaffected by channel blockade. We conclude that these results do not support the hypothesis that TRPA1-expressing cutaneous afferents play an important

  3. Transient receptor potential channel A1 and noxious cold responses in rat cutaneous nociceptors

    PubMed Central

    Dunham, J.P.; Leith, J.L.; Lumb, B.M.; Donaldson, L.F.

    2010-01-01

    The role of transient receptor potential channel A1 (TRPA1) in noxious cold sensation remains unclear. Some data support the hypothesis that TRPA1 is a transducer of noxious cold whilst other data contest it. In this study we investigated the role of TRPA1 in cold detection in cutaneous nociceptors in vivo using complementary experimental approaches. We used noxious withdrawal reflex electromyography, and single fibre recordings in vivo, to test the hypothesis that TRPA1-expressing primary afferents mediate noxious cold responses in anaesthetised rats. TRPV1 and TRPM8 agonists sensitise their cognate receptors to heat and cold stimuli respectively. Herein we show that the TRPA1 agonist cinnamaldehyde applied to the skin in anaesthetised rats did not sensitise noxious cold evoked hind limb withdrawal. In contrast, cinnamaldehyde did sensitise the C fibre-mediated noxious heat withdrawal, indicated by a significant drop in the withdrawal temperature. TRPA1 agonist thus sensitised the noxious reflex withdrawal to heat, but not cold. Thermal stimuli also sensitise transient receptor potential (TRP) channels to agonist. Activity evoked by capsaicin in teased primary afferent fibres showed a significant positive correlation with receptive field temperature, in both normal and Freund's complete adjuvant-induced cutaneous inflammation. Altering the temperature of the receptive field did not modulate TRPA1 agonist evoked-activity in cutaneous primary afferents, in either normal or inflamed skin. In addition, block of the TRPA1 channel with Ruthenium Red did not inhibit cold evoked activity in either cinnamaldehyde sensitive or insensitive cold responsive nociceptors. In cinnamaldehyde-sensitive–cold-sensitive afferents, although TRPA1 agonist-evoked activity was totally abolished by Ruthenium Red, cold evoked activity was unaffected by channel blockade. We conclude that these results do not support the hypothesis that TRPA1-expressing cutaneous afferents play an important

  4. Experimental study of frost heaving force based on transient shock response using piezoceramic sensors

    NASA Astrophysics Data System (ADS)

    Wang, Ruolin; Peng, Tongxiao; Wang, Ming L.

    2016-04-01

    In seasonally frozen soil regions, the frost heaving problem made it difficult to monitor or evaluate the pile safety for long term. So far, no mature tool can be utilized to monitor the frost heaving force, which was unevenly distributed along the pile. In this paper, a piezoceramic sensing based transient excitation response approach was proposed to monitor the frost heaving force in real time. Freeze-thaw cycles can result in great changes of soil engineering properties, including the frost heaving force. So, the freeze-thaw cycle was repeated fourth to study its effect. In the experiment, transient horizontal shock on the top of the pile will be detected by the 6 PZT sensors glued on the pile. The signal data received by the 6 PZT sensors can be used to illustrate the frost heaving force distribution along the pile. Moisture content effect is also one of the important reasons that cause the variation of soil mechanical properties. So three different moisture content (6%, 12%, 18%) testing soil were used in this experiment to detect the variance of the frost heaving force. An energy indicator was developed to quantitatively evaluate the frost heaving force applied on the pile. The experimental results showed that the proposed method was effective in monitoring the uneven distribution of frost heaving force along the pile.

  5. Modeling the reversible sink effect in response to transient contaminant sources

    SciTech Connect

    Zhao, Dongye; Little, John C.; Hodgson, Alfred T.

    2001-02-01

    A physically based diffusion model is used to evaluate the sink effect of diffusion-controlled indoor materials and to predict the transient contaminant concentration in indoor air in response to several time-varying contaminant sources. For simplicity, it is assumed the predominant indoor material is a homogeneous slab, initially free of contaminant, and the air within the room is well mixed. The model enables transient volatile organic compound (VOC) concentrations to be predicted based on the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) of the sink. Model predictions are made for three scenarios, each mimicking a realistic situation in a building. Styrene, phenol, and naphthalene are used as representative VOCs. A styrene butadiene rubber (SBR) backed carpet, vinyl flooring (VF), and a polyurethane foam (PUF) carpet cushion are considered as typical indoor sinks. In scenarios involving a sinusoidal VOC input and a double exponential decaying input, the model predicts the sink has a modest impact for SBR/styrene, but the effect increases for VF/phenol and PUF/naphthalene. In contrast, for an episodic chemical spill, SBR is predicted to reduce the peak styrene concentration considerably. A parametric study reveals for systems involving a large equilibrium constant (K), the kinetic constant (D) will govern the shape of the resulting gas-phase concentration profile. On the other hand, for systems with a relaxed mass transfer resistance, K will dominate the profile.

  6. Transient Response Analysis of Polymer Electrolyte Fuel Cell Considering Equivalent Electric Circuit and Mass Conservation

    NASA Astrophysics Data System (ADS)

    Ito, Kohei; Miyauchi, Nobuhito; Onda, Kazuo; Koori, Hironori

    Since PEFC (Polymer Electrolyte Fuel Cell) can produce electricity at high power density with a simple stack constitution, PEFC is expected to be applied to electric vehicles and to distributed power sources. In these applications, PEFC may be operated at a wide range of load and may have frequent starts and stops. Therefore it is important to elucidate the transient characteristics of PEFC. In this study, we made a mathematical model to predict the transient behavior of PEFC, considering an equivalent electric circuit and a mass conservation equation. Important physical properties, such as proton conductivity and double-layer capacitance of polymer electrolyte membrane were measured to be incorporated into the model. By using the model, we calculated the response of cell potential to a rapid change of load current, and compared the numerical calculation with the experimental result. After the rapid change of load current, the cell potential varies in 10-1s accompanied by the charge and discharge of the electric double layer capacitance, and then it changes in 101s by the re-distribution of water in the polymer electrolyte membrane.

  7. Source impedance, transient response, and noise characterization of the TOPAZ 2 reactors

    SciTech Connect

    Kusnierkiewicz, D.Y.

    1995-01-20

    Electrical measurements have been performed on the TOPAZ 2 V-71 and Ya-21 Reactors, in order to characterize the source impedance as a function of DC operating point and frequency. The response of the reactor to step changes in load current, as well as the frequency content of the electrical noise generated by the reactor have also been measured. These parameters are important to know in order to design power regulation circuitry which maintains a constant load on the reactor during spacecraft operations for any flight application of the TOPAZ 2 reactors. Voltage spikes at the reactor interface induced by load transients must be limited; the power regulation circuitry must have adequate bandwidth to compensate for spacecraft load dynamics. The methods used to make these measurements will be discussed. Results of the measurements on the Ya-21 reactor indicate the source impedance is dominated by a series resistance and inductance. The equivalent DC leakage resistance from the reactor output to structure was also measured. The self generated noise of the reactor is benign; load induced transients will be sufficiently controlled with capacitive filtering and active regulation circuitry external to the reactor/power distribution system. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

  8. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

    SciTech Connect

    Florinski, V.; Roux, J. A. le; Stone, E. C.; Cummings, A. C.

    2015-04-10

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii of heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout.

  9. Transient Response of Rotor on Rolling-Element Bearings with Clearance

    NASA Technical Reports Server (NTRS)

    Fleming, David P.; Murphy, Brian T.; Sawicki, Jerzy T.; Poplawski, J. V.

    2006-01-01

    Internal clearance in rolling element bearings is usually present to allow for radial and axial growth of the rotor-bearing system and to accommodate bearing fit-up. The presence of this clearance also introduces a "dead band" into the load-deflection behavior of the bearing. Previous studies demonstrated that the presence of dead band clearance might have a significant effect on synchronous rotor response. In this work, the authors investigate transient response of a rotor supported on rolling element bearings with internal clearance. In addition, the stiffness of the bearings varies nonlinearly with bearing deflection and with speed. Bearing properties were accurately calculated with a state of the art rolling bearing analysis code. The subsequent rotordynamics analysis shows that for rapid acceleration rates the maximum response amplitude may be less than predicted by steady-state analysis. The presence of clearance may shift the critical speed location to lower speed values. The rotor vibration response exhibits subharmonic components which are more prominent with bearing clearance.

  10. Transient autonomic responses during sustained attention in high and low fit young adults

    PubMed Central

    Luque-Casado, Antonio; Perakakis, Pandelis; Ciria, Luis F.; Sanabria, Daniel

    2016-01-01

    Maintaining vigilance over long periods of time is especially critical in performing fundamental everyday activities and highly responsible professional tasks (e.g., driving, performing surgery or piloting). Here, we investigated the role of aerobic fitness as a crucial factor related to the vigilance capacity. To this end, two groups of young adult participants (high-fit and low-fit) were compared in terms of reaction time (RT) performance and event-related heart rate responses in a 60′ version of the psychomotor vigilance task. The results showed shorter RTs in high-fit participants, but only during the first 24′ of the task. Crucially, this period of improved performance was accompanied by a decelerative cardiac response pattern present only in the high-fit group that also disappeared after the first 24′. In conclusion, high aerobic fitness was related to a pattern of transient autonomic responses suggestive of an attentive preparatory state that coincided with improved behavioural performance, and that was sustained for 24′. Our findings highlight the importance of considering the role of the autonomic nervous system reactivity in the relationship between fitness and cognition in general, and sustained attention in particular. PMID:27271980

  11. Transient Genome-Wide Transcriptional Response to Low-Dose Ionizing Radiation In Vivo in Humans

    SciTech Connect

    Berglund, Susanne R.; Rocke, David M.; Dai Jian; Schwietert, Chad W.; Santana, Alison; Stern, Robin L.; Lehmann, Joerg; Hartmann Siantar, Christine L.; Goldberg, Zelanna

    2008-01-01

    Purpose: The in vivo effects of low-dose low linear energy transfer ionizing radiation on healthy human skin are largely unknown. Using a patient-based tissue acquisition protocol, we have performed a series of genomic analyses on the temporal dynamics over a 24-hour period to determine the radiation response after a single exposure of 10 cGy. Methods and Materials: RNA from each patient tissue sample was hybridized to an Affymetrix Human Genome U133 Plus 2.0 array. Data analysis was performed on selected gene groups and pathways. Results: Nineteen gene groups and seven gene pathways that had been shown to be radiation responsive were analyzed. Of these, nine gene groups showed significant transient transcriptional changes in the human tissue samples, which returned to baseline by 24 hours postexposure. Conclusions: Low doses of ionizing radiation on full-thickness human skin produce a definable temporal response out to 24 hours postexposure. Genes involved in DNA and tissue remodeling, cell cycle transition, and inflammation show statistically significant changes in expression, despite variability between patients. These data serve as a reference for the temporal dynamics of ionizing radiation response following low-dose exposure in healthy full-thickness human skin.

  12. Topoisomerase IIalpha-dependent induction of a persistent DNA damage response in response to transient etoposide exposure.

    PubMed

    Soubeyrand, Sébastien; Pope, Louise; Haché, Robert J G

    2010-02-01

    Cytotoxicity of the topoisomerase II (topoII) poison etoposide has been ascribed to the persistent covalent trapping of topoII in DNA cleavage complexes that become lethal as cells replicate their DNA. However, short term etoposide treatment also leads to subsequent cell death, suggesting that the lesions that lead to cytotoxicity arise rapidly and prior to the onset DNA replication. In the present study 1h treatment with 25muM etoposide was highly toxic and initiated a double-stranded DNA damage response as reflected by the recruitment of ATM, MDC1 and DNA-PKcs to gammaH2AX foci. While most DNA breaks were rapidly repaired upon withdrawal of the etoposide treatment, the repair machinery remained engaged in foci for at least 24h following withdrawal. TopoII siRNA ablation showed the etoposide toxicity and gammaH2AX response to correlate with the inability of the cell to correct topoIIalpha-initiated DNA damage. gammaH2AX induction was resistant to the inhibition of DNA replication and transcription, but was increased by pre-treatment with the histone deacetylase inhibitor trichostatin A. These results link the lethality of etoposide to the generation of persistent topoIIalpha-dependent DNA defects within topologically open chromatin domains.

  13. Development of advanced modal methods for calculating transient thermal and structural response

    NASA Technical Reports Server (NTRS)

    Camarda, Charles J.

    1991-01-01

    Higher-order modal methods for predicting thermal and structural response are evaluated. More accurate methods or ones which can significantly reduce the size of complex, transient thermal and structural problems are desirable for analysis and are required for synthesis of real structures subjected to thermal and mechanical loading. A unified method is presented for deriving successively higher-order modal solutions related to previously-developed, lower-order methods such as the mode displacement and mode-acceleration methods. A new method, called the force-derivative method, is used to obtain higher-order modal solutions for both uncoupled (proportionally-damped) structural problems as well as thermal problems and coupled (non-proportionally damped) structural problems. The new method is called the force-derivative method because, analogous to the mode-acceleration method, it produces a term that depends on the forcing function and additional terms that depend on the time derivatives of the forcing function.

  14. Concurrent material point method and molecular dynamics approach for simulating transient responses

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Su, Yu-Chen; Zhang, Hetao; Jiang, Shan; Sewell, Thomas D.

    2017-01-01

    To effectively simulate multiscale transient responses such as impact and penetration without the need to invoke a master/slave treatment, the multiscale material point method (Multi-MPM) is being developed wherein molecular dynamics (MD) at the nanoscale or dissipative particle dynamics (DPD) at the mesoscale are handled concurrently within the framework of the original MPM (continuum scale). The proposed numerical scheme for concurrently linking different scales is described here along with a preliminary error analysis. Representative examples for concurrent MPM and DPD and concurrent MPM and MD simulations were presented at SCCM-2015. Because the original MPM is an extension from computational fluid dynamics to solid dynamics, the proposed Multi-MPM might also become robust for dealing with multiphase interactions involving failure evolution.

  15. Transient response of multidegree-of-freedom linear systems to forcing functions with inequality constraints

    NASA Technical Reports Server (NTRS)

    Michalopoulos, C. D.

    1974-01-01

    Optimal control theory is applied to analyze the transient response of discrete linear systems to forcing functions with unknown time dependence but having known bounds. Particular attention is given to forcing functions which include: (1) maximum displacement of any given mass element, (2) maximum relative displacement of any two adjacent masses, and (3) maximum acceleration of a given mass. Linear mechanical systems with an arbitrary number of degrees of freedom and only one forcing function acting are considered. In the general case, the desired forcing function is found to be a function that switches from the upper-to-lower bound and vice-versa at certain moments of time. A general procedure for finding such switching times is set forth.

  16. Theoretical Evaluation of the Transient Response of Constant Head and Constant Flow-Rate Permeability Tests

    USGS Publications Warehouse

    Zhang, M.; Takahashi, M.; Morin, R.H.; Esaki, T.

    1998-01-01

    A theoretical analysis is presented that compares the response characteristics of the constant head and the constant flowrate (flow pump) laboratory techniques for quantifying the hydraulic properties of geologic materials having permeabilities less than 10-10 m/s. Rigorous analytical solutions that describe the transient distributions of hydraulic gradient within a specimen are developed, and equations are derived for each method. Expressions simulating the inflow and outflow rates across the specimen boundaries during a constant-head permeability test are also presented. These solutions illustrate the advantages and disadvantages of each method, including insights into measurement accuracy and the validity of using Darcy's law under certain conditions. The resulting observations offer practical considerations in the selection of an appropriate laboratory test method for the reliable measurement of permeability in low-permeability geologic materials.

  17. Western Wind and Solar Integration Study Phase 3 – Frequency Response and Transient Stability

    SciTech Connect

    Miller, N. W.; Shao, M.; Pajic, S.; D'Aquila, R.

    2014-12-01

    Power system operators and utilities worldwide have concerns about the impact of high-penetration wind and solar generation on electric grid reliability (EirGrid 2011b, Hydro-Quebec 2006, ERCOT 2010). The stability of North American grids under these conditions is a particular concern and possible impediment to reaching future renewable energy goals. Phase 3 of the Western Wind and Solar Integration Study (WWSIS-3) considers a 33% wind and solar annual energy penetration level that results in substantial changes to the characteristics of the bulk power system, including different power flow patterns, different commitment and dispatch of existing synchronous generation, and different dynamic behavior of wind and solar generation. WWSIS-3 evaluates two specific aspects of fundamental frequency system stability: frequency response and transient stability.

  18. The $10 trillion value of better information about the transient climate response.

    PubMed

    Hope, Chris

    2015-11-13

    How much is better information about climate change worth? Here, I use PAGE09, a probabilistic integrated assessment model, to find the optimal paths of CO(2) emissions over time and to calculate the value of better information about one aspect of climate change, the transient climate response (TCR). Approximately halving the uncertainty range for TCR has a net present value of about $10.3 trillion (year 2005 US$) if accomplished in time for emissions to be adjusted in 2020, falling to $9.7 trillion if accomplished by 2030. Probabilistic integrated assessment modelling is the only method we have for making estimates like these for the value of better information about the science and impacts of climate change.

  19. LLUVIA-II: A program for two-dimensional, transient flow through partially saturated porous media; Yucca Mountain Site Characterization Project

    SciTech Connect

    Eaton, R.R.; Hopkins, P.L.

    1992-08-01

    LLUVIA-II is a program designed for the efficient solution of two- dimensional transient flow of liquid water through partially saturated, porous media. The code solves Richards equation using the method-of-lines procedure. This document describes the solution procedure employed, input data structure, output, and code verification.

  20. Effects of background noise on the response of rat and cat motoneurones to excitatory current transients.

    PubMed Central

    Poliakov, A V; Powers, R K; Sawczuk, A; Binder, M D

    1996-01-01

    1. We studied the responses of rat hypoglossal motoneurones to excitatory current transients (ECTs) using a brainstem slice preparation. Steady, repetitive discharge at rates of 12-25 impulses s-1 was elicited from the motoneurones by injecting long (40 s) steps of constant current. Poisson trains of the ECTs were superimposed on these steps. The effects of additional synaptic noise was simulated by adding a zero-mean random process to the stimuli. 2. We measured the effects of the ECTs on motoneurone discharge probability by compiling peristimulus time histograms (PSTHs) between the times of occurrence of the ECTs and the motoneurone spikes. The ECTs produced modulation of motoneurone discharge similar to that produced by excitatory postsynaptic currents. 3. The addition of noise altered the pattern of the motoneurone response to the current transients: both the amplitude and the area of the PSTH peaks decreased as the power of the superimposed noise was increased. Noise tended to reduce the efficacy of the ECTs, particularly when the motoneurones were firing at lower frequencies. Although noise also increased the firing frequency of the motoneurones slightly, the effects of noise on ECT efficacy did not simply result from noise-induced changes in mean firing rate. 4. A modified version of the experimental protocol was performed in lumbar motoneurones of intact, pentobarbitone-anaesthetized cats. These recordings yielded results similar to those obtained in rat hypoglossal motoneurones in vitro. 5. Our results suggest that the presence of concurrent synaptic inputs reduces the efficacy of any one input. The implications of this change in efficacy and the possible underlying mechanisms are discussed. PMID:8866358

  1. A Precision and High-Speed Behavioral Simulation Method for Transient Response and Frequency Characteristics of Switching Converters

    NASA Astrophysics Data System (ADS)

    Sai, Toru; Sugimoto, Shoko; Sugimoto, Yasuhiro

    We propose a fast and precise transient response and frequency characteristics simulation method for switching converters. This method uses a behavioral simulation tool without using a SPICE-like analog simulator. The nonlinear operation of the circuit is considered, and the nonlinear function is realized by defining the nonlinear formula based on the circuit operation and by applying feedback. To assess the accuracy and simulation time of the proposed simulation method, we designed current-mode buck and boost converters and fabricated them using a 0.18-µm high-voltage CMOS process. The comparison in the transient response and frequency characteristics among SPICE, the proposed program on a behavioral simulation tool which we named NSTVR (New Simulation Tool for Voltage Regulators) and experiments of fabricated IC chips showed good agreement, while NSTVR was more than 22 times faster in transient response and 85 times faster in frequency characteristics than SPICE in CPU time in a boost converter simulation.

  2. Simulations of the transient climate response to climate engineering in the form of cirrus cloud seeding

    NASA Astrophysics Data System (ADS)

    Storelvmo, Trude; Boos, William R.

    2015-04-01

    We present a global modeling study of a so far understudied climate engineering mechanism (CEM), namely the seeding of cirrus clouds to reduce their lifetimes in the upper troposphere, and hence their greenhouse effect. Different from most CEMs, the intention of cirrus seeding is not to reduce the amount of solar radiation reaching Earth's surface. This particular CEM rather targets the greenhouse effect, by reducing the trapping of infrared radiation by high clouds. This avoids some of the caveats that have been identified for solar radiation management, for example the delayed recovery of stratospheric ozone or drastic changes to Earth's hydrological cycle. Here, we contrast transient simulations of the 21st century, using a modified version of the Community Earth System Model (CESM). We simulate three future scenarios: (i) A simulation with the conventional high emission scenario RCP8.5, (ii) A simulation in which climate engineering in the form of high-latitude cirrus seeding is introduced in the middle of the century without any accompanying emission reductions, and (iii) The same as (ii), but with emissions that are reduced by 50% over the period 2050 to 2100. We consider the last scenario to be one in which climate engineering is used to buy time for mitigation efforts to become effective, while scenario (iii) is one in which high emissions are allowed to continue due to the naïve belief that climate engineering can be used to prevent global warming in perpetuity. Our analysis focuses on the contrasts between the regional and global climates of year 2100 produced by the three scenarios.

  3. Measured responsivities of generation II and hybrid image intensifiers

    SciTech Connect

    Yates, G.J.; King, N.S.P.; Thomas, M.C.

    1995-07-01

    We have measured the absolute and coupled system responsivities of several image intensifier types at several wavelengths in the visible spectrum. Intensifiers characterized include microchannel plate (MCP) generation II proximity-focused and hybrid generation I/generation II electrostatic-focused designs. Configurations including single plate, double plate, nominal and high strip current MCPs, and standard S20 and super generation II enhanced S-20 photocathodes were evaluated. Absolute responsivity measurements were performed using NIST-traceable radiometry instrumentation. The normalized relative sensitivities and overall optical luminous gain performance provided by individual intensifiers when similarly coupled to either high resolution 10-bit RS-170 CCD or FPS cameras are presented along with their radiometric data.

  4. Magnetohydrodynamic simulations of transient transpolar potential responses to solar wind density changes

    NASA Astrophysics Data System (ADS)

    Ober, D. M.; Wilson, G. R.; Burke, W. J.; Maynard, N. C.; Siebert, K. D.

    2007-10-01

    Magnetohydrodynamic (MHD) simulations are used to examine the response of the transpolar potential (ΦTP) to changes in the solar wind density during periods of constant solar wind electric field. For increases (decreases) in the solar wind density ΦTP responds immediately by increasing (decreasing) from the steady state values. In both cases the response of ΦTP is transient, decaying to near initial steady state values even when the density change persists. The magnitude of the ΦTP response is proportional to both the rate of erosion of the dayside magnetopause and the ionospheric Pedersen conductance. In our MHD simulations ΦTP is driven entirely by the dayside merging rate and is insensitive to changes in the nightside reconnection rate. The observed relationship between the modeled dayside merging rate and ΦTP is well characterized by an L-R circuit equation derived from integrating Faraday's Law around the Region 1 current loop. The inductive time constant for variations in the transpolar potential was found to be 6.5 (13) minutes for simulations using ionospheric Pedersen conductances of 6 (12) mhos. This corresponds in both cases to a magnetosphere-ionosphere inductance of 65 Henries. Observations of the transpolar potential derived using the assimilative mapping of ionospheric electrodynamics (AMIE) model are presented and shown to be consistent with the simulation results.

  5. Molecular and Cellular Responses to Interleukin-4 Treatment in a Rat Model of Transient Ischemia

    PubMed Central

    Lively, Starlee; Hutchings, Sarah

    2016-01-01

    Within hours after stroke, potentially cytotoxic pro-inflammatory mediators are elevated within the brain; thus, one potential therapeutic strategy is to reduce them and skew the brain toward an anti-inflammatory state. Because interleukin-4 (IL-4) treatment induces an anti-inflammatory, “alternative-activation” state in microglia and macrophages in vitro, we tested the hypothesis that early supplementation of the brain with IL-4 can shift it toward an anti-inflammatory state and reduce damage after transient focal ischemia. Adult male rat striata were injected with endothelin-1, with or without co-injection of IL-4. Inflammation, glial responses and damage to neurons and white matter were quantified from 1 to 7 days later. At 1 day, IL-4 treatment increased striatal expression of several anti-inflammatory markers (ARG1, CCL22, CD163, PPARγ), increased phagocytic (Iba1-positive, CD68-positive) microglia/macrophages, and increased VEGF-A-positive infiltrating neutrophils in the infarcts. At 7 days, there was evidence of sustained, propagating responses. IL-4 increased CD206, CD200R1, IL-4Rα, STAT6, PPARγ, CD11b, and TLR2 expression and increased microglia/macrophages in the infarct and astrogliosis outside the infarct. Neurodegeneration and myelin damage were not reduced, however. The sustained immune and glial responses when resolution and repair processes have begun warrant further studies of IL-4 treatment regimens and long-term outcomes. PMID:27634961

  6. Transcriptomics Modeling of the Late-Gestation Fetal Pituitary Response to Transient Hypoxia

    PubMed Central

    Wood, Charles E.; Chang, Eileen I.; Richards, Elaine M.; Rabaglino, Maria Belen; Keller-Wood, Maureen

    2016-01-01

    Background The late-gestation fetal sheep responds to hypoxia with physiological, neuroendocrine, and cellular responses that aid in fetal survival. The response of the fetus to hypoxia represents a coordinated effort to maximize oxygen transfer from the mother and minimize wasteful oxygen consumption by the fetus. While there have been many studies aimed at investigating the coordinated physiological and endocrine responses to hypoxia, and while immunohistochemical or in situ hybridization studies have revealed pathways supporting the endocrine function of the pituitary, there is little known about the coordinated cellular response of the pituitary to the hypoxia. Results Thirty min hypoxia (from 17.0±1.7 to 8.0±0.8 mm Hg, followed by 30 min normoxia) upregulated 595 and downregulated 790 genes in fetal pituitary (123–132 days’ gestation; term = 147 days). Network inference of up- and down- regulated genes revealed a high degree of functional relatedness amongst the gene sets. Gene ontology analysis revealed upregulation of cellular metabolic processes (e.g., RNA synthesis, response to estrogens) and downregulation of protein phosphorylation, protein metabolism, and mitosis. Genes found to be at the center of the network of upregulated genes included genes important for purine binding and signaling. At the center of the downregulated network were genes involved in mRNA processing, DNA repair, sumoylation, and vesicular trafficking. Transcription factor analysis revealed that both up- and down-regulated gene sets are enriched for control by several transcription factors (e.g., SP1, MAZ, LEF1, NRF1, ELK1, NFAT, E12, PAX4) but not for HIF-1, which is known to be an important controller of genomic responses to hypoxia. Conclusions The multiple analytical approaches used in this study suggests that the acute response to 30 min of transient hypoxia in the late-gestation fetus results in reduced cellular metabolism and a pattern of gene expression that is

  7. Transient magnetorheological response of magnetoactive elastomers to step and pyramid excitations.

    PubMed

    Belyaeva, Inna A; Kramarenko, Elena Yu; Stepanov, Gennady V; Sorokin, Vladislav V; Stadler, Dominik; Shamonin, Mikhail

    2016-03-21

    Transient rheological response of magnetoactive elastomers is experimentally studied using dynamic torsion at a fixed oscillation frequency in temporally stepwise changing magnetic fields and oscillation amplitudes. For step magnetic-field excitations, at least three exponential functions are required to reasonably describe the time behavior of the storage shear modulus over long time scales (>10(3) s). The deduced characteristic time constants of the corresponding rearrangement processes of the filler network differ approximately by one order of magnitude: τ1 ≲ 10(1) s, τ2 ∼ 10(2) s, and τ3 ∼ 10(3) s. The sudden imposition of the external magnetic field activates a very fast rearrangement process with the characteristic time under 10 s, which cannot be determined more precisely due to the measurement conditions. Even more peculiar transient behavior has been observed during pyramid excitations, when either the external magnetic field was first stepwise increased and then decreased in a staircase manner at a fixed strain amplitude γ or the strain amplitude γ was first stepwise increased and then decreased in a staircase manner at a fixed magnetic field. In particular, the so-called "cross-over effect" has been identified in both dynamical loading programs. This cross-over effect seems to be promoted by the application of the external magnetic field. The experimental results are discussed in the context of the specific rearrangement of the magnetic filler network under the simultaneous action of the external magnetic field and shear deformation. Striking similarities of the observed phenomena to the structural relaxation processes in glassy materials and to the jamming transition of granular materials are pointed out. The obtained results are important for fundamental understanding of material behavior in magnetic fields as well as for the development of devices on the basis of magnetoactive elastomeric materials.

  8. Gestational therapy with an angiotensin II receptor antagonist and transient renal failure in a premature infant.

    PubMed

    Bass, J Kirk; Faix, Roger G

    2006-07-01

    The fetotoxic effects of angiotensin converting enzyme inhibitors when used during the second half of pregnancy are well known. The more recently developed angiotensin II receptor antagonists appear to yield similar fetal abnormalities. We report a premature infant born to a 41-year-old mother with a long history of infertility who had received losartan therapy for hypertension throughout an undetected pregnancy. Ultrasound examination 2 days prior to delivery identified a single fetus at 29 weeks gestation, anhydramnios, and an empty fetal bladder. The neonatal course was complicated by oliguria, hyperkalemia, marked renal dysfunction, respiratory failure, joint contractures, and a large anterior fontanelle with widely separated sutures. Hypotension (mean arterial pressure<25 torr) on day 1 responded to volume expansion, dopamine, and hydrocortisone. Serum creatinine reached a maximum of 2.7 mg/dL on day 6 and decreased to 0.4 by day 56. No formal urinalysis was performed, but the urine was reported to be visually clear throughout the course. Although a renal ultrasound on day 2 was normal, a follow-up study at 7 months revealed bilateral generalized parenchymal echogenicity, consistent with medical renal disease. Since then, weight and length have been at the 5th percentile or less, with apparent renal tubular acidosis necessitating the addition of sodium citrate supplements. This case emphasizes the importance of maintaining a high index of suspicion for potential pregnancy when contemplating the use of a drug of this class, and considering serial testing for pregnancy when using such drugs, even in patients with a longstanding history of infertility.

  9. Transient Stability and Frequency Response of the US Western Interconnection under conditions of High Wind and Solar Generation

    SciTech Connect

    Clark, Kara; Miller, Nicholas W.; Shao, Miaolei; Pajic, Slobodan; D'Aquila, Robert

    2015-04-15

    Adding large amounts of wind and solar generation to bulk power systems that are traditionally subject to operating constraints set by transient stability and frequency response limitations is the subject of considerable concern in the industry. The US Western Interconnection (WI) is expected to experience substantial additional growth in both wind and solar generation. These plants will, to some extent, displace large central station thermal generation, both coal and gas-fired, which have traditionally helped maintain stability. Our paper reports the results of a study that investigated the transient stability and frequency response of the WI with high penetrations of wind and solar generation. Moreover, the main goals of this work were to (1) create a realistic, baseline model of the WI, (2) test selected transient stability and frequency events, (3) investigate the impact of large amounts of wind and solar generation, and (4) examine means to improve performance.

  10. Global electromagnetic induction in the moon and planets. [poloidal eddy current transient response

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.

    1973-01-01

    Experiments and analyses concerning electromagnetic induction in the moon and other extraterrestrial bodies are summarized. The theory of classical electromagnetic induction in a sphere is first considered, and this treatment is extended to the case of the moon, where poloidal eddy-current response has been found experimentally to dominate other induction modes. Analysis of lunar poloidal induction yields lunar internal electrical conductivity and temperature profiles. Two poloidal-induction analytical techniques are discussed: a transient-response method applied to time-series magnetometer data, and a harmonic-analysis method applied to data numerically Fourier-transformed to the frequency domain, with emphasis on the former technique. Attention is given to complicating effects of the solar wind interaction with both induced poloidal fields and remanent steady fields. The static magnetization field induction mode is described, from which are calculated bulk magnetic permeability profiles. Magnetic field measurements obtained from the moon and from fly-bys of Venus and Mars are studied to determine the feasibility of extending theoretical and experimental induction techniques to other bodies in the solar system.

  11. Evaluating the dynamic response of in-flight thrust calculation techniques during throttle transients

    NASA Technical Reports Server (NTRS)

    Ray, Ronald J.

    1994-01-01

    New flight test maneuvers and analysis techniques for evaluating the dynamic response of in-flight thrust models during throttle transients have been developed and validated. The approach is based on the aircraft and engine performance relationship between thrust and drag. Two flight test maneuvers, a throttle step and a throttle frequency sweep, were developed and used in the study. Graphical analysis techniques, including a frequency domain analysis method, were also developed and evaluated. They provide quantitative and qualitative results. Four thrust calculation methods were used to demonstrate and validate the test technique. Flight test applications on two high-performance aircraft confirmed the test methods as valid and accurate. These maneuvers and analysis techniques were easy to implement and use. Flight test results indicate the analysis techniques can identify the combined effects of model error and instrumentation response limitations on the calculated thrust value. The methods developed in this report provide an accurate approach for evaluating, validating, or comparing thrust calculation methods for dynamic flight applications.

  12. Transient expression of protein tyrosine phosphatases encoded in Cotesia plutellae bracovirus inhibits insect cellular immune responses

    NASA Astrophysics Data System (ADS)

    Ibrahim, Ahmed M. A.; Kim, Yonggyun

    2008-01-01

    Several immunosuppressive factors are associated with parasitism of an endoparasitoid wasp, Cotesia plutellae, on the diamondback moth, Plutella xylostella. C. plutellae bracovirus (CpBV) encodes a large number of putative protein tyrosine phosphatases (PTPs), which may play a role in inhibiting host cellular immunity. To address this inhibitory hypothesis of CpBV-PTPs, we performed transient expression of individual CpBV-PTPs in hemocytes of the beet armyworm, Spodoptera exigua, and analyzed their cellular immune responses. Two different forms of CpBV-PTPs were chosen and cloned into a eukaryotic expression vector under the control of the p10 promoter of baculovirus: one with the normal cysteine active site (CpBV-PTP1) and the other with a mutated active site (CpBV-PTP5). The hemocytes transfected with CpBV-PTP1 significantly increased in PTP activity compared to control hemocytes, but those with CpBV-PTP5 exhibited a significant decrease in the PTP activity. All transfected hemocytes exhibited a significant reduction in both cell spreading and encapsulation activities compared to control hemocytes. Co-transfection of CpBV-PTP1 together with its double-stranded RNA reduced the messenger RNA (mRNA) level of CpBV-PTP1 and resulted in recovery of both hemocyte behaviors. This is the first report demonstrating that the polydnaviral PTPs can manipulate PTP activity of the hemocytes to interrupt cellular immune responses.

  13. An evaluation of higher-order model methods for calculating transient structural response

    NASA Technical Reports Server (NTRS)

    Camarda, Charles J.; Haftka, Raphael T.; Riley, Michael F.

    1987-01-01

    A higher-order modal method proposed by Leung for transient structural analysis entitled the force-derivative method is evaluated. This method repeatedly integrates by parts with respect to time the convolution-integral form of the structural response to produce successively better approximations to the contribution of the higher modes which are neglected in the modal summation. Comparisons are made of the force-derivative, the mode-displacement, and the mode-acceleration methods for several numerical example problems for various times, levels of damping, and forcing functions. The example problems include a tip-loaded cantilevered beam and a simply-supported multispan beam. The force-derivative method is shown to converge to an accurate solution in fewer modes than either the mode-displacement or the mode-acceleration methods. In addition, for problems in which there are a large number of closely-spaced frequencies whose mode shapes have a negligible contribution to the response, the force-derivative method is very effective in representing the effect of the important, but otherwise neglected, higher modes.

  14. Whole-body irradiation transiently diminishes the adrenocorticotropin response to recombinant human interleukin-1{alpha}

    SciTech Connect

    Perlstein, R.S.; Mehta, N.R.; Neta, R.; Whitnall, M.H.; Mougey, E.H.

    1995-03-01

    Recombinant human interleukin-1{alpha} (rhIL-1{alpha}) has significant potential as a radioprotector and/or treatment for radiation-induced hematopoietic injury. Both IL-1 and whole-body ionizing irradiation acutely stimulate the hypothalamic-pituitary-adrenal axis. We therefore assessed the interaction of whole-body irradiation and rhIL-1{alpha} in altering the functioning of the axis in mice. Specifically, we determined the adrenocorticotropin (ACTH) and corticosterone responses to rhIL-1{alpha} administered just before and hours to days after whole-body or sham irradiation. Our results indicate that whole-body irradiation does not potentiate the rhIL-1{alpha}-induced increase in ACTH levels at the doses used. In fact, the rhIL-1{alpha}-induced increase in plasma ACTH is transiently impaired when the cytokine is administered 5 h after, but not 1 h before, exposure to whole-body irradiation. The ACTH response may be inhibited by elevated corticosterone levels after whole-body irradiation, or by other radiation-induced effects on the pituitary gland and hypothalamus. 36 refs., 3 figs.

  15. Dynamic Response in Transient Stress-Field Behavior Induced by Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Jenkins, Andrew

    Hydraulic fracturing is a technique which is used to exploit geologic features and subsurface properties in an effort to increase production in low-permeability formations. The process of hydraulic fracturing provides a greater surface contact area between the producing formation and the wellbore and thus increases the amount of recoverable hydrocarbons from within the reservoir. The use of this stimulation technique has brought on massive applause from the industry due to its widespread success and effectiveness, however the dynamic processes that take part in the development of hydraulic fractures is a relatively new area of research with respect to the massive scale operations that are seen today. The process of hydraulic fracturing relies upon understanding and exploiting the in-situ stress distribution throughout the area of study. These in-situ stress conditions are responsible for directing fracture orientation and propagation paths throughout the period of injection. The relative magnitude of these principle stresses is key in developing a successful stimulation plan. In horizontal well plan development the interpretation of stress within the reservoir is required for determining the azimuth of the horizontal well path. These horizontal laterals are typically oriented in a manner such that the well path lies parallel to the minimum horizontal stress. This allows for vertical fractures to develop transversely to the wellbore, or normal to the least principle stress without the theoretical possibility of fractures overlapping, creating the most efficient use of the fluid energy during injection. The orientation and magnitude of these in-situ stress fields however can be dynamic, controlled by the subsequent fracture propagation and redistribution of the surrounding stresses. That is, that as the fracture propagates throughout the reservoir, the relative stress fields surrounding the fractures may see a shift and deviate from their original direction or

  16. Transient Treg-cell depletion in adult mice results in persistent self-reactive CD4(+) T-cell responses.

    PubMed

    Nyström, Sofia N; Bourges, Dorothée; Garry, Sarah; Ross, Ellen M; van Driel, Ian R; Gleeson, Paul A

    2014-12-01

    Depletion of Foxp3(+) CD4(+) regulatory T cells (Treg) in adults results in chronic inflammation and autoimmune disease. However, the impact of transient Treg-cell depletion on self-reactive responses is poorly defined. Here, we studied the effect of transient depletion of Treg cells on CD4(+) T-cell responses to endogenous self-antigens. Short-term ablation of Treg cells in mice resulted in rapid activation of CD4(+) T cells, increased percentage of IFN-γ(+) and Th17 cells in lymphoid organs, and development of autoimmune gastritis. To track self-reactive responses, we analyzed the activation of naïve gastric-specific CD4(+) T cells. There was a dramatic increase in proliferation and acquisition of effector function of gastric-specific T cells in the stomach draining LNs of Treg-cell-depleted mice, compared with untreated mice, either during Treg-cell depletion or after Treg-cell reconstitution. Moreover, the hyperproliferation of gastric-specific T cells in the Treg-cell-ablated mice was predominantly antigen-dependent. Transient depletion of Treg cells resulted in a shift in the ratio of peripheral:thymic Treg cells in the reemerged Treg-cell population, indicating an altered composition of Treg cells. These findings indicate that transient Treg-cell depletion results in ongoing antigen-driven self-reactive T-cell responses and emphasize the continual requirement for an intact Treg-cell population.

  17. Transient In Vivo Resistance Mechanisms of Burkholderia pseudomallei to Ceftazidime and Molecular Markers for Monitoring Treatment Response

    PubMed Central

    Cummings, Jason E.; Slayden, Richard A.

    2017-01-01

    Much is known about the mode of action of drugs and resistance mechanisms under laboratory growth conditions, but research on the bacterial transcriptional response to drug pressure in vivo or efficacious mode of action and transient resistance mechanisms of clinically employed drugs is limited. Accordingly, to assess active alternative metabolism and transient resistance mechanisms, and identify molecular markers of treatment response, the in vivo transcriptional response of Burkholderia pseudomallei 1026b to treatment with ceftazidime in infected lungs was compared to the in vitro bacterial response in the presence of drug. There were 1,688 transcriptionally active bacterial genes identified that were unique to in vivo treated conditions. Of the in vivo transcriptionally active bacterial genes, 591 (9.4% coding capacity) genes were differentially expressed by ceftazidime treatment. In contrast, only 186 genes (2.7% coding capacity) were differentially responsive to ceftazidime treatment under in vitro culturing conditions. Within the genes identified were alternative PBP proteins that may compensate for target inactivation and transient resistance mechanisms, such as β-lactamses that may influence the potency of ceftazidime. This disparate observation is consistent with the thought that the host environment significantly alters the bacterial metabolic response to drug exposure compared to the response observed under in vitro growth. Notably, this study revealed 184 bacterial genes and ORFs that were unique to in vivo ceftazidime treatment and thus provide candidate molecular markers for treatment response. This is the first report of the unique transcriptional response of B. pseudomallei from host tissues in an animal model of infection and elucidates the in vivo metabolic vulnerabilities, which is important in terms of defining the efficacious mode of action and transient resistance mechanisms of a frontline meliodosis chemotherapeutic, and biomarkers for

  18. The transient response of ice volume to orbital-driven climate changes of the Late Pliocene

    NASA Astrophysics Data System (ADS)

    de Boer, Bas; Hunter, Stephen; Dolan, Aisling; Haywood, Alan

    2016-04-01

    The contribution to sea-level rise of the Antarctic and Greenland ice sheets in a warming climate is uncertain. A better understanding is evidently needed to make more rigorous projections of the impact of regional sea-level rise. A warm interval within the Late Pliocene (3.264 to 3.025 million years before present) can be used to gain a better understanding of the response of the ice sheets to a warming climate with CO2 levels close to or higher than present. Here, we will use a unique ice-sheet - sea-level model, ANICE-SELEN and couple this to the full-complexity intermediate-resolution FAMOUS climate model for the Late Pliocene interval. A first approach is presented here with a one-way coupling, using FAMOUS to force the ice-sheet models in a transient mode. The FAMOUS simulation is driven by PRISM3 boundary conditions (which were also used in PlioMIP phase 1), where we apply a changing orbit, with and without dynamic vegetation. This 40 kyr simulation is centred on the warm interglacial peak, MIS KM5c (3.225 to 3.185 Myr ago). This experiment will give a first indication of the response of the Greenland and Antarctic ice sheets to the climate of the Late Pliocene. The results are compared with the equilibrated response of the ice sheet on Greenland and Antarctica to the PlioMIP phase 1 climate model output, as done so for the PLISMIP experiments.

  19. A model of northern treeline dynamics in response to transient changes in climate

    SciTech Connect

    Stuart, C.F. III; Starfield, A.M. )

    1994-06-01

    In order to predict the future distribution of boreal vegetation, we developed what, to our knowledge, is the first model of ecosystem change in response to transient changes in climate and disturbance regime over the next 50-500 yr. The model develops scenarios of change in disturbance regime and ecosystem type in what is currently arctic tundra in response to GCM-based scenarios of climate change. Seed availability, tree growth rate, and probability of fire were the model parameters that most strongly influenced the balance between tundra and boreal forest during transitional climates. The rate of climatic warming strongly affected the time lag between climate change and the simulated ecosystem response but had less effect on the rate or pattern of ecosystem change. The model calculated that a ramped change of 3[degrees] in the next century (corresponding to average rate of warming predicted by GCMs) would lead to a 150 yr lag preceeding any change from tundra to forest, followed by rates of forestation of up to 6-12% per decade. The model predicted that tundra would first be invaded by conifer forests, but that the proportion of broad-leafed deciduous forest would increase as climate continued to warm due to increased fire frequency. The pattern of climatic warming had strong effects on simulated rates of conversion from tundra to forest. Rapid step changes in climate or increases in climatic variability both promoted more rapid ecosystem change than did ramped change in climate or climatic oscillations, particularly when oscillations were long relative to the time required for tree growth to reproductive maturity.

  20. The analysis of the transient pressure response of the shuttle EPS-ECS cryogenic tanks with external pressurization systems

    NASA Technical Reports Server (NTRS)

    Barton, J. E.; Patterson, H. W.

    1973-01-01

    An analysis of transient pressures in externally pressurized cryogenic hydrogen and oxygen tanks was conducted and the effects of design variables on pressure response determined. The analysis was conducted with a computer program which solves the compressible viscous flow equations in two-dimensional regions representing the tank and external loop. The external loop volume, thermal mass, and heat leak were the dominant design variables affecting the system pressure response. No significant temperature stratification occurred in the fluid contained in the tank.

  1. Estimating transient climate response using consistent temperature reconstruction methods in models and observations

    NASA Astrophysics Data System (ADS)

    Richardson, M.; Cowtan, K.; Hawkins, E.; Stolpe, M.

    2015-12-01

    Observational temperature records such as HadCRUT4 typically have incomplete geographical coverage and blend air temperature over land with sea surface temperatures over ocean, in contrast to model output which is commonly reported as global air temperature. This complicates estimation of properties such as the transient climate response (TCR). Observation-based estimates of TCR have been made using energy-budget constraints applied to time series of historical radiative forcing and surface temperature changes, while model TCR is formally derived from simulations where CO2 increases at 1% per year. We perform a like-with-like comparison using three published energy-budget methods to derive modelled TCR from historical CMIP5 temperature series sampled in a manner consistent with HadCRUT4. Observation-based TCR estimates agree to within 0.12 K of the multi-model mean in each case and for 2 of the 3 energy-budget methods the observation-based TCR is higher than the multi-model mean. For one energy-budget method, using the HadCRUT4 blending method leads to a TCR underestimate of 0.3±0.1 K, relative to that estimated using global near-surface air temperatures.

  2. Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor

    SciTech Connect

    Klepper, C.C.; Hogan, J.T.; Owen, L.W.; Mioduszewski, P.K.; Maingi, R.; Hill, D.N.; Buchenauer, D.; Ali Mahdavi, M.; Schaffer, M.J.; Petrie, T.W.; Jackson, G.L.; Evans, T.E.; Haas, G.

    1992-05-01

    The DIII-D divertor baffle system was designed to facilitate density control in long pulse H-mode discharges by removing a particle flux equal to the neutral beam fueling rate ({approximately}20 Torr-1/s) with a {approximately}1mTorr neutral pressure under the baffle (p{sub 0}). Initial measurements of the baffle pressure indicated that p{sub 0}{approximately} 10 mTorr (without pumping or biasing), a value much in excess of that required for long pulse density control. Radial sweeps of the X-point position have been employed to determine the maximum p{sub 0}, as well as to establish the dependence of this pressure on geometry. An estimate of the particle equilibration time for the baffle system has been made by studying the baffle pressure response to ``giant`` ELM effects. ``Steady state`` experiments in which the X-point position was fixed for {approximately}2.5s have also been carried out and steady baffle pressures were observed. The scaling of baffle pressure with plasma parameters has been found to be similar under transient and ``steady state`` conditions. Detailed modeling of these experiments with the B2, DEGAS, and WDIFFUSE (wall model) codes has been made.

  3. Inferring the Mode of Selection from the Transient Response to Demographic Perturbations

    NASA Astrophysics Data System (ADS)

    Balick, Daniel; Do, Ron; Reich, David; Sunyaev, Shamil

    2014-03-01

    Despite substantial recent progress in theoretical population genetics, most models work under the assumption of a constant population size. Deviations from fixed population sizes are ubiquitous in natural populations, many of which experience population bottlenecks and re-expansions. The non-equilibrium dynamics introduced by a large perturbation in population size are generally viewed as a confounding factor. In the present work, we take advantage of the transient response to a population bottleneck to infer features of the mode of selection and the distribution of selective effects. We develop an analytic framework and a corresponding statistical test that qualitatively differentiates between alleles under additive and those under recessive or more general epistatic selection. This statistic can be used to bound the joint distribution of selective effects and dominance effects in any diploid sexual organism. We apply this technique to human population genetic data, and severely restrict the space of allowed selective coefficients in humans. Additionally, one can test a set of functionally or medically relevant alleles for the primary mode of selection, or determine the local regional variation in dominance coefficients along the genome.

  4. A multi-signature brain-computer interface: use of transient and steady-state responses

    NASA Astrophysics Data System (ADS)

    Severens, Marianne; Farquhar, Jason; Duysens, Jacques; Desain, Peter

    2013-04-01

    Objective. The aim of this paper was to increase the information transfer in brain-computer interfaces (BCI). Therefore, a multi-signature BCI was developed and investigated. Stimuli were designed to simultaneously evoke transient somatosensory event-related potentials (ERPs) and steady-state somatosensory potentials (SSSEPs) and the ERPs and SSSEPs in isolation. Approach. Twelve subjects participated in two sessions. In the first session, the single and combined stimulation conditions were compared on these somatosensory responses and on the classification performance. In the second session the on-line performance with the combined stimulation was evaluated while subjects received feedback. Furthermore, in both sessions, the performance based on ERP and SSSEP features was compared. Main results. No difference was found in the ERPs and SSSEPs between stimulation conditions. The combination of ERP and SSSEP features did not perform better than with ERP features only. In both sessions, the classification performances based on ERP and combined features were higher than the classification based on SSSEP features. Significance. Although the multi-signature BCI did not increase performance, it also did not negatively impact it. Therefore, such stimuli could be used and the best performing feature set could then be chosen individually.

  5. Modeling the transient response of saline intrusion to rising sea-levels.

    PubMed

    Webb, Matt D; Howard, Ken W F

    2011-01-01

    Sea levels are expected to rise as a result of global temperature increases, one implication of which is the potential exacerbation of sea water intrusion into coastal aquifers. Given that approximately 70% of the world's population resides in coastal regions, it is imperative to understand the interaction between fresh groundwater and sea water intrusion in order to best manage available resources. For this study, controlled investigation has been carried out concerning the temporal variation in sea water intrusion as a result of rising sea levels. A series of fixed inland head two-dimensional sea water intrusion models were developed with SEAWAT in order to assess the impact of rising sea levels on the transient migration of saline intrusion in coastal aquifers under a range of hydrogeological property conditions. A wide range of responses were observed for typical hydrogeological parameter values. Systems with a high ratio of hydraulic conductivity to recharge and high effective porosity lagged behind the equilibrium sea water toe positions during sea-level rise, often by many hundreds of meters, and frequently taking several centuries to equilibrate following a cease in sea-level rise. Systems with a low ratio of hydraulic conductivity to recharge and low effective porosity did not develop such a large degree of disequilibrium and generally stabilized within decades following a cease in sea-level rise. This study provides qualitative initial estimates for the expected rate of intrusion and predicted degree of disequilibrium generated by sea-level rise for a range of hydrogeological parameter values.

  6. Transient response of Ge:Be and Ge:Zn FIR photoconductors under low background photon flux conditions

    NASA Technical Reports Server (NTRS)

    Haegel, N. M.; Haller, E. E.

    1986-01-01

    An experimental study of the transient behavior of Ge:Be and Ge:Zn photoconductors to changes in photon flux rates has been performed under the low background flux conditions (10 to the 8th photon/s) typical of astronomy and astrophysics applications. A characteristic transient behavior with time constants ranging from 0.1 to greater than 5 s has been observed in both materials when the shallow levels are very closely compensated. The detector response consists of both a fast and a slow component. The amplitude of the slow component can be up to 10 times greater than the initial fast component. It has been established that this phenomenon cannot be explained by current models of carrier sweep-out or dielectric relaxation. The transient behavior has been characterized as a function of temperature, electric field, photoconductive gain and material parameters.

  7. Groundwater response to changing water-use practices in sloping aquifers using convolution of transient response functions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study examines the impact of a sloping base on the movement of transients through groundwater systems. Dimensionless variables and regression of model results are employed to develop functions relating the transient change in saturated thickness to the distance upgradient and downgradient from ...

  8. TRANSIENT RESPONSE OF ABLATING AXISYMMETRIC BODIES INCLUDING THE EFFECTS OF SHAPE CHANGE

    NASA Technical Reports Server (NTRS)

    Howser, L. M.

    1994-01-01

    A computer program has been developed to analyze the transient response of an ablating axisymmetric body, including the effect of shape change. The governing differential equation, the boundary conditions for the analysis on which the computer program is based, and the method of solution of the resulting finite-difference equations are discussed in the documentation. Some of the features of the analysis and the associated program are (1) the ablation material is considered to be orthotropic with temperature-dependent thermal properties; (2) the thermal response of the entire body is considered simultaneously; (3) the heat transfer and pressure distribution over the body are adjusted to the new geometry as ablation occurs; (4) the governing equations and several boundary-condition options are formulated in terms of generalized orthogonal coordinates for fixed points in a moving coordinate system; (5) the finite-difference equations are solved implicitly; and (6) other instantaneous body shapes can be displayed with a user-supplied plotting routine. The physical problem to be modeled with the analysis is described by FORTRAN input variables. For example, the external body geometry is described in the W, Z coordinates; material density is given; and the stagnation cold-wall heating rate is given in a time-dependent array. Other input variables are required which control the solution, specify boundary conditions, and determine output from the program. The equations have been programmed so that either the International System of Units or the U. S. Customary Units may be used. This program is written in FORTRAN IV for batch execution and has been implemented on a CDC 6000 Series computer. This program was developed in 1972.

  9. Characterizing the transient geomorphic response to base-level fall in the northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhang, Huiping; Kirby, Eric; Pitlick, John; Anderson, Robert S.; Zhang, Peizhen

    2017-02-01

    Analysis of hillslope gradient, landscape relief, and channel steepness in the Daxia River basin provides evidence of a transient geomorphic response to base-level fall on the northeastern Tibetan Plateau. Low-gradient channels and gentle hillslopes of the upper watershed are separated from a steeper, high-relief landscape by a series of convex knickzones along channel longitudinal profiles. Downstream projection of the "relict" portions of the profiles implies 800-850 m of incision, consistent with geologic and geomorphic records of post 1.7 Ma incision in the lower watershed. We combine optically stimulated luminescence dating of fluvial terrace deposits to constrain incision rates downstream of knickpoints with catchment-averaged 10Be concentrations in modern sediment to estimate erosion rates in tributary basins both above and below knickpoints. Both sources of data imply landscape lowering rates of 300 m Ma-1 below the knickpoint and 50-100 m Ma-1 above. Field measurements of channel width (n = 48) and calculations of bankfull discharge (n = 9) allow determination of scaling relations among channel hydraulic geometry, discharge, and contributing area that we employ to estimate the patterns of basal shear stress, unit stream power, and bed load transport rate throughout the channel network. Our results imply a clear downstream increase of incision potential; this result would appear to be consistent with a detachment-limited response to imposed base-level fall, in which steepening of channels drives an increase in erosion rates. In contrast, however, we do not observe apparent narrowing of channels across the transition from slowly eroding to rapidly eroding portions of the watershed. Rather, the present-day channel morphology as well as its scaling of hydraulic geometry imply that the river is primarily adjusted to transport its sediment load and suggest that channel morphology may not always reflect the presence of knickpoints and differences in landscape

  10. Response of cyt a,a3 in the situ canine heart to transient ischemic episodes.

    PubMed

    Snow, T R; Kleinmann, L H; LaManna, J C; Wechsler, A S; Jöbsis, F F

    1981-01-01

    Experiments were performed to examine the response of cyt a,a3 to transient ischemic and hypoxic episodes in the empty, fibrillating canine heart in situ. Using a dual wavelength, differential spectrophotometer, reaction spectra show an absorption peak at approximately 605 nm consistent with that obtained from purified cyt a,a3. The characteristics of the averaged reaction spectrum in the interval 590 nm to 610 nm indicate that hemoglobin/myoglobin contribute no more than 23% to the signal measured at 605 nm. A regimen of one 30 sec global ischemia (GI) repeated once every 3 minutes over a 90 min period showed no appreciable signal deterioration. Therefore, five such interventions were subsequently used as the test perturbation. Studies of the effects of ischemic episodes of 30 and 60 min show that the response of cyt a,a3 to this test intervention was smaller (90 +/- 6% and 89 +/- 7%) than that observed prior to the ischemic episode. Changes in coronary perfusion pressure (+/- 10 Torr) produced an immediate oxidation/reduction of cyt a,a3. In the working heart, just prior to fibrillation, 6 sec to interrupted ventilation resulted in a continuous reduction of cyt a,a3. The data from these studies show: 1) The redox state of cyt a,a3 may be continuously monitored in the canine heart in situ. 2) Following ischemias of 30 and 60 min duration, respiratory chain function may be impaired; and 3) The well-perfused epicardium is extremely sensitive to small changes in oxygen delivery.

  11. The ocean's role in the transient response of climate to abrupt greenhouse gas forcing

    NASA Astrophysics Data System (ADS)

    Marshall, John; Scott, Jeffery R.; Armour, Kyle C.; Campin, J.-M.; Kelley, Maxwell; Romanou, Anastasia

    2015-04-01

    We study the role of the ocean in setting the patterns and timescale of the transient response of the climate to anthropogenic greenhouse gas forcing. A novel framework is set out which involves integration of an ocean-only model in which the anthropogenic temperature signal is forced from the surface by anomalous downwelling heat fluxes and damped at a rate controlled by a `climate feedback' parameter. We observe a broad correspondence between the evolution of the anthropogenic temperature () in our simplified ocean-only model and that of coupled climate models perturbed by a quadrupling of . This suggests that many of the mechanisms at work in fully coupled models are captured by our idealized ocean-only system. The framework allows us to probe the role of the ocean in delaying warming signals in the Southern Ocean and in the northern North Atlantic, and in amplifying the warming signal in the Arctic. By comparing active and passive temperature-like tracers we assess the degree to which changes in ocean circulation play a role in setting the distribution and evolution of . The background ocean circulation strongly influences the large-scale patterns of ocean heat uptake and storage, such that is governed by an advection/diffusion equation and weakly damped to the atmosphere at a rate set by climate feedbacks. Where warming is sufficiently small, for example in the Southern Ocean, changes in ocean circulation play a secondary role. In other regions, most noticeably in the North Atlantic, changes in ocean circulation induced by are central in shaping the response.

  12. Ecological robustness of the gut microbiota in response to ingestion of transient food-borne microbes

    PubMed Central

    Zhang, Chenhong; Derrien, Muriel; Levenez, Florence; Brazeilles, Rémi; Ballal, Sonia A; Kim, Jason; Degivry, Marie-Christine; Quéré, Gaëlle; Garault, Peggy; van Hylckama Vlieg, Johan E T; Garrett, Wendy S; Doré, Joël; Veiga, Patrick

    2016-01-01

    Resident gut microbes co-exist with transient bacteria to form the gut microbiota. Despite increasing evidence suggesting a role for transient microbes on gut microbiota function, the interplay between resident and transient members of this microbial community is poorly defined. We aimed to determine the extent to which a host's autochthonous gut microbiota influences niche permissivity to transient bacteria using a fermented milk product (FMP) as a vehicle for five food-borne bacterial strains. Using conventional and gnotobiotic rats and gut microbiome analyses (16S rRNA genes pyrosequencing and reverse transcription qPCR), we demonstrated that the clearance kinetics of one FMP bacterium, Lactococcus lactis CNCM I-1631, were dependent on the structure of the resident gut microbiota. Susceptibility of the resident gut microbiota to modulation by FMP intervention correlated with increased persistence of L. lactis. We also observed gut microbiome configurations that were associated with altered stability upon exposure to transient bacteria. Our study supports the concept that allochthonous bacteria have transient and subject-specific effects on the gut microbiome that can be leveraged to re-engineer the gut microbiome and improve dysbiosis-related diseases. PMID:26953599

  13. A numerical comparison with an exact solution for the transient response of a cylinder immersed in a fluid. [computer simulated underwater tests to determine transient response of a submerged cylindrical shell

    NASA Technical Reports Server (NTRS)

    Giltrud, M. E.; Lucas, D. S.

    1979-01-01

    The transient response of an elastic cylindrical shell immersed in an acoustic media that is engulfed by a plane wave is determined numerically. The method applies to the USA-STAGS code which utilizes the finite element method for the structural analysis and the doubly asymptotic approximation for the fluid-structure interaction. The calculations are compared to an exact analysis for two separate loading cases: a plane step wave and an exponentially decaying plane wave.

  14. Transient response in longitudinal grain size to reduced sediment supply in a large river

    NASA Astrophysics Data System (ADS)

    Singer, Michael

    2010-05-01

    Bed material grain size is an important degree of freedom in fluvial systems as they adjust to system-wide perturbations such as sediment supply changes. However, little is known about processes and patterns of such adjustment in longitudinal grain size sorting in large rivers. This research uses unprecedented datasets collected in a large fluvial system to investigate transient response to recent supply changes associated with anthropogenic activities. Separate fining trends for gravel and fines, a protracted gravel-sand (G-S) transition, and bed patchiness identified in Singer (2008) were interrogated using output from a hydraulic model with grain size distributions (GSDs) extracted from ~125 cross sections spanning ~400 river kilometers of the Sacramento River, California. The analysis suggests that interactions between hydraulics, bed material sorting, and sediment flux explain these previously identified anomalies. Highest values of sorting occur in the G-S transition and represent the overlap of separate fining trends for gravel and fines, where the long profile is jagged with evidence of progressive incision. Much of the sediment in this poorly sorted zone is organized into patches, where transport apparently occurs as bedload sheets. Patchiness occurs over short length scales leading to strong differences in entrainment and flux, regardless of hydraulic conditions. A modified Shields stress is proposed that is scaled by GSD sorting to improve characterization of entrainment/disentrainment. Sediment flux calculations based on an equation sensitive bed material conditions (Singer and Dunne, 2004) reveal a strong relationship between fine sediment flux and d90, suggesting that the efficiency of fine patch flux controls bed material bed surface roughness. Results are in part consistent with Paola and Seal (1995) suggesting that patches are a result of overlapping pdfs of shear stress and sorting and with Ferguson (2003) in that the final end of the protracted G

  15. A numerical algorithm to evaluate the transient response for a synchronous scanning streak camera using a time-domain Baum-Liu-Tesche equation

    NASA Astrophysics Data System (ADS)

    Pei, Chengquan; Tian, Jinshou; Wu, Shengli; He, Jiai; Liu, Zhen

    2016-10-01

    The transient response is of great influence on the electromagnetic compatibility of synchronous scanning streak cameras (SSSCs). In this paper we propose a numerical method to evaluate the transient response of the scanning deflection plate (SDP). First, we created a simplified circuit model for the SDP used in an SSSC, and then derived the Baum-Liu-Tesche (BLT) equation in the frequency domain. From the frequency-domain BLT equation, its transient counterpart was derived. These parameters, together with the transient-BLT equation, were used to compute the transient load voltage and load current, and then a novel numerical method to fulfill the continuity equation was used. Several numerical simulations were conducted to verify this proposed method. The computed results were then compared with transient responses obtained by a frequency-domain/fast Fourier transform (FFT) method, and the accordance was excellent for highly conducting cables. The benefit of deriving the BLT equation in the time domain is that it may be used with slight modifications to calculate the transient response and the error can be controlled by a computer program. The result showed that the transient voltage was up to 1000 V and the transient current was approximately 10 A, so some protective measures should be taken to improve the electromagnetic compatibility.

  16. DEFORM-4: fuel pin characterization and transient response in the SAS4A accident analysis code system

    SciTech Connect

    Miles, K.J.; Hill, D.J.

    1986-01-01

    The DEFORM-4 module is the segment of the SAS4A Accident Analysis Code System that calculates the fuel pin characterization in response to a steady state irradiation history, thereby providing the initial conditions for the transient calculation. The various phenomena considered include fuel porosity migration, fission gas bubble induced swelling, fuel cracking and healing, fission gas release, cladding swelling, and the thermal-mechanical state of the fuel and cladding. In the transient state, the module continues the thermal-mechanical response calculation, including fuel melting and central cavity pressurization, until cladding failure is predicted and one of the failed fuel modules is initiated. Comparisons with experimental data have demonstrated the validity of the modeling approach.

  17. Transient Responses of Gravel Bars to Increases in Sediment Supply - Field & Flume

    NASA Astrophysics Data System (ADS)

    Podolak, C.

    2010-12-01

    Bedforms in a gravel-bed river respond to a combination of water discharge, the rate and size of sediment supply, and valley-scale geometry. This study investigates bar response to an increase in sediment supply. In a large flume (2.75 m wide) with a plane bed of mixed sand and gravel (gravel D50 = 10 mm; 15% sand), alternate bars were formed by inducing a slight perturbation in the flow at the upstream end. After the bars and sediment flux reached a steady state, sediment supply was increased (from 45 kg/min to 70 kg/min). After the bed and sediment flux reached steady state, sediment supply was again increased (from 70 kg/min to 140 kg/min). Throughout the experiment high-frequency (1 Hz) measurements of the sediment flux, as well as moderate frequency (every 90 minutes) measurements of the bed topography were made. As the channel increased transport capacity to match the increased sediment supply, the initial bed adjustment was an increase in slope with near uniform deposition in the cross-stream direction. The bed then evolved to a steady-state configuration in which the locations and dimensions of the bars and pools were very similar to the pre-augmentation condition. During the adjustment process, the cross-stream relief initially decreased, the bar wavelengths decreased, and the bar celerity increased. The evolution from the lower-relief interim state to the post-augmentation steady state was reminiscent of initial bar development from a plane bed. A similar sequence of bed adjustment was observed on the Sandy River, Oregon, following a large increase in sediment flux due to the 2007 Marmot Dam removal. Measurements of bedform evolution immediately downstream of the dam show a transition from a long high-relief lateral bar along the right bank, to a lower-relief multiple short wavelength mid-channel bars, finally back to a long high-relief lateral bar along the right bank, albeit 4-5 meters higher than the original. Previous work on bedform response to

  18. Analysis of the photosystem II by modelling the fluorescence yield transients during 10 seconds after a 10 ns pulse

    NASA Astrophysics Data System (ADS)

    Belyaeva, Natalya E.; Schmitt, Franz-Josef; Paschenko, Vladimir Z.; Riznichenko, Galina Yu.; Rubin, Andrew B.

    2014-10-01

    The dynamics of the photosystem II (PS II) redox states is imitated over nine orders of magnitude in time. Our simulations focus on the information of the chlorophyll a fluorescence induced by a 10 ns laser flash. The PS II model analyzes differences in the PS II reaction between leaves (A. Thaliana, spinach) and thermophilic Chlorella cells.

  19. Stability, Transient Response, Control, and Safety of a High-Power Electric Grid for Turboelectric Propulsion of Aircraft

    NASA Technical Reports Server (NTRS)

    Armstrong, Michael; Ross, Christine; Phillips, Danny; Blackwelder, Mark

    2013-01-01

    This document contains the deliverables for the NASA Research and Technology for Aerospace Propulsion Systems (RTAPS) regarding the stability, transient response, control, and safety study for a high power cryogenic turboelectric distributed propulsion (TeDP) system. The objective of this research effort is to enumerate, characterize, and evaluate the critical issues facing the development of the N3-X concept aircraft. This includes the proposal of electrical grid architecture concepts and an evaluation of any needs for energy storage.

  20. Transient temperature and sea level response of a two-dimensional ocean-climate model to greenhouse gas increases

    SciTech Connect

    Harvey, L.D.D.

    1994-09-01

    A two-dimensional dynamical ocean model is coupled to an energy balance climate model and used to investigate the transient surface temperature and sea level response to greenhouse gas increases. For most experiments a step function surface-troposphere heating perturbation of 6 W/sq m is applied. A transient reduction in the thermohaline overturning flux of 15-30% occurs in most experiments, although in some cases a near-total circulation collapse occurs within the first 100 years and lasts 700-1000 years. The transient circulation decrease is attributed to the greater rate of downward penetration of the heating anomaly in downwelling rather than in upwelling regions and is not a result of reduced convection. For experiments in which the steady state circulation is qualitatively unchanged after a heating perturbation, the surface temperature response is roughly uniform with latitude, in the absence of ice and snow. However, in some cases a heating perturbation induces the transition from a one-cell to a two-cell overturning circulation, or causes a complete reversal in the direction of overturning when a single cell spans both hemispheres, causing marked latitudinal variations in the surface temperature response.

  1. Dynamic response of a lightweight gun barrel during a firing-pressure transient

    SciTech Connect

    McGrath, S.V.; Phillips, L.P. Jr.

    1990-04-01

    This report presents the results of a nonlinear, dynamic structural analysis of a gun barrel design during a firing-pressure transient. The final design was defined by an iterative design/analysis process in which the effects of design modifications were compared with established design criteria. The ADINA finite element code was used to analyze the titanium/carbon composite gun barrel assembly for a maximum transient pressure of 29,000 psi. The gun barrel weighs 42 lb; however, a significant potential exists for weight savings in future gun barrel designs. 2 refs., 41 figs.

  2. Transient Ecotone Response to Climatic Change: Some Conceptual and Modelling Approaches.

    PubMed

    Neilson, Ronald P

    1993-08-01

    Accurate prediction of the ecological impacts of climatic change is a pressing challenge to the science of ecology. The current state of the art for broad-scale estimates of change in biomes and ecotones between biomes is limited to equilibrium estimates of ecological change under some future equilibrium climate. Uncertainties in these estimates abound, ranging from uncertainties in future climate scenarios to uncertainties in our ecological models and finally to uncertainties in modelling the feedbacks between the climate and the biosphere. Ecologists and policymakers need to go beyond equilibrium estimates of biosphere change to transient responses of the biosphere as the climate changes. Ecotones between biomes have been suggested as sensitive areas of change that could be effectively modelled and monitored for future change. Ecotones are also important in influencing local and regional biodiversity patterns and ecological flows. The ecological processes that could affect change at ecotones and within biomes are discussed; they include internal ecosystem processes, such as competition, and external abiotic processes, most notably drought and related disturbances. Drought followed by infestations and fire appears to be the most likely process that could mediate ecological change under a rapidly changing climate. The impacts would be apparent all across biomes, not just at ecotones. However, specific predictions about the dynamics of ecotones can be made qualitatively, based on a theory of patch scaling and diversity in relation to abiotic stressors. Under current conditions, the size of homogeneous patches is expected to be small at ecotones, but to enlarge with distance from the ecotone. Directional climatic change should promote a coalescence of patches on one side of the ecotone and increased fragmentation on the other side. Ecotones should begin to blur as viewed from a satellite only to re-form at some later date in a new location. This view is in contrast

  3. Transient response to three-phase faults on a wind turbine generator. Ph.D. Thesis - Toledo Univ.

    NASA Technical Reports Server (NTRS)

    Gilbert, L. J.

    1978-01-01

    In order to obtain a measure of its responses to short circuits a large horizontal axis wind turbine generator was modeled and its performance was simulated on a digital computer. Simulation of short circuit faults on the synchronous alternator of a wind turbine generator, without resort to the classical assumptions generally made for that analysis, indicates that maximum clearing times for the system tied to an infinite bus are longer than the typical clearing times for equivalent capacity conventional machines. Also, maximum clearing times are independent of tower shadow and wind shear. Variation of circuit conditions produce the modifications in the transient response predicted by analysis.

  4. The detector response matrices of the burst and transient source experiment (BATSE) on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Horack, John M.; Lestrade, John Patrick

    1995-01-01

    The detector response matrices for the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) are described, including their creation and operation in data analysis. These response matrices are a detailed abstract representation of the gamma-ray detectors' operating characteristics that are needed for data analysis. They are constructed from an extensive set of calibration data coupled with a complex geometry electromagnetic cascade Monte Carlo simulation code. The calibration tests and simulation algorithm optimization are described. The characteristics of the BATSE detectors in the spacecraft environment are also described.

  5. A Simple Control Strategy Using Speedy Transient Response for Multiphase Buck Converter

    NASA Astrophysics Data System (ADS)

    Sasikala, K.; Ravikumar, D.; Rubini, B.

    2017-03-01

    The high performance of recent originating digital processors requires power supply for transient output, firm voltage regulation and high current. Industry has taken up interleaved multiphase synchronous buck converters for meeting such demands. Application of the voltage mode (ripple) hysteretic strategy to multiphase Voltage Regulator Units (VRU) would help satisfying many of the upcoming digital processors and IC’s powering demands. This arises from the use of the various advantages that can be obtained from this technique. This current division method is known for several benefits it provides: easy accessibility in application to all control methods, with freedom from the prime control technique in voltage regulation loop, absence of any necessity for current reference, better accuracy in current division of equal magnitude at almost every load conditions in standstill and transients. As against this, there are several challenges that involve distribution of multiple control signals, current sharing and sensitivity to noise, high speed comparators, hysteretic band accuracy and stable at large load transients. In addition, application of the current division technique presented was made to a multiphase voltage mode ripple controlled Buck Converter that produced a novel and easy control strategy having minimum output voltage ripples and speedy transient output.

  6. Classification methods for noise transients in advanced gravitational-wave detectors II: performance tests on Advanced LIGO data

    NASA Astrophysics Data System (ADS)

    Powell, Jade; Torres-Forné, Alejandro; Lynch, Ryan; Trifirò, Daniele; Cuoco, Elena; Cavaglià, Marco; Heng, Ik Siong; Font, José A.

    2017-02-01

    The data taken by the advanced LIGO and Virgo gravitational-wave detectors contains short duration noise transients that limit the significance of astrophysical detections and reduce the duty cycle of the instruments. As the advanced detectors are reaching sensitivity levels that allow for multiple detections of astrophysical gravitational-wave sources it is crucial to achieve a fast and accurate characterization of non-astrophysical transient noise shortly after it occurs in the detectors. Previously we presented three methods for the classification of transient noise sources. They are Principal Component Analysis for Transients (PCAT), Principal Component LALInference Burst (PC-LIB) and Wavelet Detection Filter with Machine Learning (WDF-ML). In this study we carry out the first performance tests of these algorithms on gravitational-wave data from the Advanced LIGO detectors. We use the data taken between the 3rd of June 2015 and the 14th of June 2015 during the 7th engineering run (ER7), and outline the improvements made to increase the performance and lower the latency of the algorithms on real data. This work provides an important test for understanding the performance of these methods on real, non stationary data in preparation for the second advanced gravitational-wave detector observation run, planned for later this year. We show that all methods can classify transients in non stationary data with a high level of accuracy and show the benefits of using multiple classifiers.

  7. The frontline antibiotic vancomycin induces a zinc starvation response in bacteria by binding to Zn(II)

    PubMed Central

    Zarkan, Ashraf; Macklyne, Heather-Rose; Truman, Andrew W.; Hesketh, Andrew R.; Hong, Hee-Jeon

    2016-01-01

    Vancomycin is a front-line antibiotic used for the treatment of nosocomial infections, particularly those caused by methicillin-resistant Staphylococcus aureus. Despite its clinical importance the global effects of vancomycin exposure on bacterial physiology are poorly understood. In a previous transcriptomic analysis we identified a number of Zur regulon genes which were highly but transiently up-regulated by vancomycin in Streptomyces coelicolor. Here, we show that vancomycin also induces similar zinc homeostasis systems in a range of other bacteria and demonstrate that vancomycin binds to Zn(II) in vitro. This implies that vancomycin treatment sequesters zinc from bacterial cells thereby triggering a Zur-dependent zinc starvation response. The Kd value of the binding between vancomycin and Zn(II) was calculated using a novel fluorometric assay, and NMR was used to identify the binding site. These findings highlight a new biologically relevant aspect of the chemical property of vancomycin as a zinc chelator. PMID:26797186

  8. THEORETICAL ANALYSIS OF THE TRANSIENT PRESSURE RESPONSE FROM A CONSTANT FLOW RATE HYDRAULIC CONDUCTIVITY TEST.

    USGS Publications Warehouse

    Morin, Roger H.; Olsen, Harold W.

    1987-01-01

    Incorporating a flow pump into a conventional triaxial laboratory system allows fluid to be supplied to or withdrawn from the base of a sediment sample at small and constant rates. An initial transient record of hydraulic head versus time is observed which eventually stabilizes to a constant steady state gradient across the sample; values of hydraulic conductivity can subsequently be determined from Darcy's law. In this paper, analytical methods are presented for determining values of specific storage and hydraulic conductivity from the initial transient phase of such a constant flow rate test. These methods are based on a diffusion equation involving pore pressure and are analogous to those used to describe the soil consolidation process and also to interpret aquifer properties from pumping tests.

  9. Transient response of glomerular filtration rate and renal blood flow to step changes in arterial pressure.

    PubMed

    Jackson, T E; Guyton, A C; Hall, J E

    1977-11-01

    Measurement of rapid renal hemodynamic changes were made for 90 s in pentobarbital-anesthetized dogs following step increases and decreases in renal arterial pressure between 80 and 120 mm Hg. Transient analysis was used to observe time characteristics of the autoregulatory relationships which are obscured in steadystate measurements. Temporal decoupling of blood flow and glomerular filtration rate (GFR) occurred with both step increases and decreases of arterial pressure. Steady-state autoregulation of blood flow was attained in about 30 s, whereas steady-state autoregulation of GFR was not demonstrably attained even 90 s after the arterial pressure maneuver. The temporal decoupling of renal blood flow and GRR supports the concept of transient involvement of proximal tubular dynamics and efferent resistance changes during acute autoregulation of GFR following step changes in arterial pressure.

  10. Modeling Longitudinal Preclinical Tumor Size Data to Identify Transient Dynamics in Tumor Response to Antiangiogenic Drugs

    PubMed Central

    Mueller, H‐J; Gaffney, EA; Maini, PK; Wagg, J; Phipps, A; Boetsch, C; Byrne, HM; Ribba, B

    2016-01-01

    Experimental evidence suggests that antiangiogenic therapy gives rise to a transient window of vessel normalization, within which the efficacy of radiotherapy and chemotherapy may be enhanced. Preclinical experiments that measure components of vessel normalization are invasive and expensive. We have developed a mathematical model of vascular tumor growth from preclinical time‐course data in a breast cancer xenograft model. We used a mixed‐effects approach for model parameterization, leveraging tumor size data to identify a period of enhanced tumor growth that could potentially correspond to the transient window of vessel normalization. We estimated the characteristics of the window for mice treated with an anti‐VEGF antibody (bevacizumab) or with a bispecific anti‐VEGF/anti‐angiopoietin‐2 antibody (vanucizumab). We show how the mathematical model could theoretically be used to predict how to coordinate antiangiogenic therapy with radiotherapy or chemotherapy to maximize therapeutic effect, reducing the need for preclinical experiments that directly measure vessel normalization parameters. PMID:27863175

  11. Early and delayed long-term transcriptional changes and short-term transient responses during cold acclimation in olive leaves

    PubMed Central

    Leyva-Pérez, María de la O; Valverde-Corredor, Antonio; Valderrama, Raquel; Jiménez-Ruiz, Jaime; Muñoz-Merida, Antonio; Trelles, Oswaldo; Barroso, Juan Bautista; Mercado-Blanco, Jesús; Luque, Francisco

    2015-01-01

    Low temperature severely affects plant growth and development. To overcome this constraint, several plant species from regions having a cool season have evolved an adaptive response, called cold acclimation. We have studied this response in olive tree (Olea europaea L.) cv. Picual. Biochemical stress markers and cold-stress symptoms were detected after the first 24 h as sagging leaves. After 5 days, the plants were found to have completely recovered. Control and cold-stressed plants were sequenced by Illumina HiSeq 1000 paired-end technique. We also assembled a new olive transcriptome comprising 157,799 unigenes and found 6,309 unigenes differentially expressed in response to cold. Three types of response that led to cold acclimation were found: short-term transient response, early long-term response, and late long-term response. These subsets of unigenes were related to different biological processes. Early responses involved many cold-stress-responsive genes coding for, among many other things, C-repeat binding factor transcription factors, fatty acid desaturases, wax synthesis, and oligosaccharide metabolism. After long-term exposure to cold, a large proportion of gene down-regulation was found, including photosynthesis and plant growth genes. Up-regulated genes after long-term cold exposure were related to organelle fusion, nucleus organization, and DNA integration, including retrotransposons. PMID:25324298

  12. Early and delayed long-term transcriptional changes and short-term transient responses during cold acclimation in olive leaves.

    PubMed

    Leyva-Pérez, María de la O; Valverde-Corredor, Antonio; Valderrama, Raquel; Jiménez-Ruiz, Jaime; Muñoz-Merida, Antonio; Trelles, Oswaldo; Barroso, Juan Bautista; Mercado-Blanco, Jesús; Luque, Francisco

    2015-02-01

    Low temperature severely affects plant growth and development. To overcome this constraint, several plant species from regions having a cool season have evolved an adaptive response, called cold acclimation. We have studied this response in olive tree (Olea europaea L.) cv. Picual. Biochemical stress markers and cold-stress symptoms were detected after the first 24 h as sagging leaves. After 5 days, the plants were found to have completely recovered. Control and cold-stressed plants were sequenced by Illumina HiSeq 1000 paired-end technique. We also assembled a new olive transcriptome comprising 157,799 unigenes and found 6,309 unigenes differentially expressed in response to cold. Three types of response that led to cold acclimation were found: short-term transient response, early long-term response, and late long-term response. These subsets of unigenes were related to different biological processes. Early responses involved many cold-stress-responsive genes coding for, among many other things, C-repeat binding factor transcription factors, fatty acid desaturases, wax synthesis, and oligosaccharide metabolism. After long-term exposure to cold, a large proportion of gene down-regulation was found, including photosynthesis and plant growth genes. Up-regulated genes after long-term cold exposure were related to organelle fusion, nucleus organization, and DNA integration, including retrotransposons.

  13. Use of NAD(P)H and Flavoprotein Autofluorescence Transients to Probe Neuron and Astrocyte Responses to Synaptic Activation

    PubMed Central

    Shuttleworth, C. William

    2010-01-01

    Synaptic stimulation in brain slices is accompanied by changes in tissue autofluorescence, which are a consequence of changes in tissue metabolism. Autofluorescence excited by ultraviolet light has been most extensively studied, and is due to reduced pyridine nucleotides (NADH and NADPH, collectively termed NAD(P)H). Stimulation generates a characteristic compound NAD(P)H response, comprising an initial fluorescence decrease and then an overshooting increase that slowly recovers to baseline levels. Evoked NAD(P)H transients are relatively easy to record, do not require the addition of exogenous indicators and have good signal-noise ratios. These characteristics make NAD(P)H imaging methods very useful for tracking the spread of neuronal activity in complex brain tissues, however the cellular basis of synaptically-evoked autofluorescence transients has been the subject of recent debate. Of particular importance is the question of whether signals are due primarily to changes in neuronal mitochondrial function, and/or whether astrocyte metabolism triggered by glutamate uptake may be a significant contributor to the overshooting NAD(P)H fluorescence increases. This mini-review addresses the subcellular origins of NAD(P)H autofluorescence and the evidence for mitochondrial and glycolytic contributions to compound transients. It is concluded that there is no direct evidence for a contribution to NAD(P)H signals from glycolysis in astrocytes following synaptic glutamate uptake. In contrast, multiple lines of evidence, including from complimentary flavoprotein autofluorescence signals, imply that mitochondrial NADH dynamics in neurons dominate compound evoked NAD(P)H transients. These signals are thus appropriate for studies of mitochondrial function and dysfunction in brain slices, in addition to providing robust maps of postsynaptic neuronal activation following physiological activation. PMID:20036704

  14. Seismic analysis of the large 70-meter antenna, part 1: Earthquake response spectra versus full transient analysis

    NASA Technical Reports Server (NTRS)

    Kiedron, K.; Chian, C. T.

    1985-01-01

    As a check on structure safety aspects, two approaches in seismic analysis for the large 70-m antennas are presented. The first approach, commonly used by civil engineers, utilizes known recommended design response spectra. The second approach, which is the full transient analysis, is versatile and applicable not only to earthquake loading but also to other dynamic forcing functions. The results obtained at the fundamental structural frequency show that the two approaches are in good agreement with each other and both approaches show a safe design. The results also confirm past 64-m antenna seismic studies done by the Caltech Seismology Staff.

  15. The Cervico-Ocular Reflex of normal human subjects in response to transient and sinusoidal trunk rotations

    NASA Technical Reports Server (NTRS)

    Sawyer, Robert N., Jr.; Thurston, Stephen E.; Becker, Keith R.; Ackley, Charles V.; Seidman, Scott H.; Leigh, R. John

    1994-01-01

    We used the magnetic search coil technique to measure the horizontal cervico-ocular reflex (COR) of 8 subjects in response to transient or sinusoidal (0.1-1.0 Hz) trunk rotations while their heads were firmly immobilized. Although we were able to resolve eye rotations of less than 0.05 deg, the COR was hardly measurable (gain was always less than 0.07). This finding, made with the most precise measurement technique used to date, suggests that the COR makes a negligible contribution to the stability of gaze in normal subjects during natural activities.

  16. CFORM- LINEAR CONTROL SYSTEM DESIGN AND ANALYSIS: CLOSED FORM SOLUTION AND TRANSIENT RESPONSE OF THE LINEAR DIFFERENTIAL EQUATION

    NASA Technical Reports Server (NTRS)

    Jamison, J. W.

    1994-01-01

    CFORM was developed by the Kennedy Space Center Robotics Lab to assist in linear control system design and analysis using closed form and transient response mechanisms. The program computes the closed form solution and transient response of a linear (constant coefficient) differential equation. CFORM allows a choice of three input functions: the Unit Step (a unit change in displacement); the Ramp function (step velocity); and the Parabolic function (step acceleration). It is only accurate in cases where the differential equation has distinct roots, and does not handle the case for roots at the origin (s=0). Initial conditions must be zero. Differential equations may be input to CFORM in two forms - polynomial and product of factors. In some linear control analyses, it may be more appropriate to use a related program, Linear Control System Design and Analysis (KSC-11376), which uses root locus and frequency response methods. CFORM was written in VAX FORTRAN for a VAX 11/780 under VAX VMS 4.7. It has a central memory requirement of 30K. CFORM was developed in 1987.

  17. Evaluation of transient response of spinning solar sail with flexible membrane by eigenfunction analysis and continuum analysis

    NASA Astrophysics Data System (ADS)

    Chujo, Toshihiro; Kawaguchi, Junichiro

    2016-10-01

    This study evaluates the transient response of large spinning membrane structures in space - especially spinning solar sails - by two different methods. A flexible sail membrane is easily deformed when a spacecraft changes its attitude, such as when using thrusters, and the control response including membrane vibration must be estimated in advance of operation. In order to estimate the motion of the membrane, numerical simulations using a multi-particle model (MPM) are conducted, where the membrane is modeled with masses, spring, and dampers. Usually, force propagation is calculated directly in this model and the position and velocity of each particle represent the membrane motion, which is referred to as a continuum analysis in this study. This method is useful for the analysis of membrane vibration because it replaces the complex dynamics with simple equations of motion. However, the computational cost is high and the calculations require a considerable amount of time. This study introduces an eigenfunction analysis to solve this problem. In this method, natural vibration modes and natural frequencies for the entire spacecraft are derived and used for dynamics computation, which reduces the computational cost dramatically compared to the conventional continuum analysis. In this study, the transient response of a spinning solar sail is analyzed using both methods, and the advantages and disadvantages are discussed. It is shown that the eigenfunction analysis provides a suitable method for acquiring approximate solutions in a very low computation time.

  18. Transient Response to Rapid Cooling of a Stainless Steel Sodium Heat Pipe

    NASA Technical Reports Server (NTRS)

    Mireles, Omar R.; Houts, Michael G.

    2011-01-01

    Compact fission power systems are under consideration for use in long duration space exploration missions. Power demands on the order of 500 W, to 5 kW, will be required for up to 15 years of continuous service. One such small reactor design consists of a fast spectrum reactor cooled with an array of in-core alkali metal heat pipes coupled to thermoelectric or Stirling power conversion systems. Heat pipes advantageous attributes include a simplistic design, lack of moving parts, and well understood behavior. Concerns over reactor transients induced by heat pipe instability as a function of extreme thermal transients require experimental investigations. One particular concern is rapid cooling of the heat pipe condenser that would propagate to cool the evaporator. Rapid cooling of the reactor core beyond acceptable design limits could possibly induce unintended reactor control issues. This paper discusses a series of experimental demonstrations where a heat pipe operating at near prototypic conditions experienced rapid cooling of the condenser. The condenser section of a stainless steel sodium heat pipe was enclosed within a heat exchanger. The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a pressure of 50 Torr of helium. The heat pipe was brought to steady state operating conditions using graphite resistance heaters then cooled by a high flow of gaseous nitrogen through the heat exchanger. Subsequent thermal transient behavior was characterized by performing an energy balance using temperature, pressure and flow rate data obtained throughout the tests. Results indicate the degree of temperature change that results from a rapid cooling scenario will not significantly influence thermal stability of an operating heat pipe, even under extreme condenser cooling conditions.

  19. Design of structure/control systems with transient response constraints exhibiting relative minima

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Jin, I. M.

    1992-01-01

    Structural optimization problems involving dynamic behavior constraints often exhibit nonconvex design spaces. The direct application of a global optimization algorithm requires a large number of function evaluations which in term require a large number of dynamic structural analyses. This work presents a strategy aimed at finding the global optimum for problems with transient dynamic behavior constraints based on approximation concepts. The method consists of generating and solving a sequence of approximate problems using a global optimizer. The approximations are explicit and capture the inherent nonconvexity of the exact functions. A simple example problem is presented.

  20. Transient behavior of flare-associated solar wind. II - Gas dynamics in a nonradial open field region

    NASA Technical Reports Server (NTRS)

    Nagai, F.

    1984-01-01

    Transient behavior of flare-associated solar wind in the nonradial open field region is numerically investigated, taking into account the thermal and dynamical coupling between the chromosphere and the corona. A realistic steady solar wind is constructed which passes through the inner X-type critical point in the rapidly diverging region. The wind speed shows a local maximum at the middle, O-type, critical point. The wind's density and pressure distributions decrease abruptly in the rapidly diverging region of the flow tube. The transient behavior of the wind following flare energy deposition includes ascending and descending conduction fronts. Thermal instability occurs in the lower corona, and ascending material flows out through the throat after the flare energy input ceases. A local density distribution peak is generated at the shock front due to the pressure deficit just behind the shock front.

  1. Active control of the forced and transient response of a finite beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John T.

    1990-01-01

    Structural vibrations from a point force are modelled on a finite beam. This research explores the theoretical limit on controlling beam vibrations utilizing another point source as an active controller. Three different types of excitation are considered, harmonic, random, and transient. For harmonic excitation, control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam. Control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, integrating the expected value of the displacement squared over the required interval, is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. The form of the controller is specified as either one or two delayed pulses, thus constraining the controller to be casual. The best possible control is examined while varying the region of control and the controller location. It is found that control is always possible using either one or two control pulses.

  2. Nonlinear transient response analysis for double walls with a porous material supported by nonlinear springs using FEM and MSKE method

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Takao; Hozumi, Hiroaki; Hirano, Yuta; Tobita, Kazuhiro; Kurosawa, Yoshio

    2014-01-01

    In this paper, we newly propose a fast computation method for the nonlinear transient responses including coupling between nonlinear springs and sound proof structures having porous materials using FEM. In this method, we extend our numerical method named as Modal Strain and Kinetic Method (i.e. MSKE method proposed previously by Yamaguchi who is one of the authors) from linear damping analysis to nonlinear dynamic analysis. We assume that the restoring force of the spring has cubic nonlinearity and linear hysteresis damping. To calculate damping properties for soundproof structures including elastic body, viscoelastic body and porous body, displacement vectors as common unknown variable are solved under coupled condition. The damped sound fields in the porous materials are defined by complex effective density and complex bulk modulus. The discrete equations in physical coordinate for this system are transformed into nonlinear ordinary coupled differential equations using normal coordinates corresponding to linear natural modes. Further, using MSKE method, modal damping can be derived approximately under coupled conditions between hysteresis damping of viscoelastic materials, damping of the springs and damping due to flow resistance in porous materials. The modal damping is used for the nonlinear differential equation to compute nonlinear transient responses.

  3. Active Control of the Forced and Transient Response of a Finite Beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John Theodore

    1989-01-01

    When studying structural vibrations resulting from a concentrated source, many structures may be modelled as a finite beam excited by a point source. The theoretical limit on cancelling the resulting beam vibrations by utilizing another point source as an active controller is explored. Three different types of excitation are considered, harmonic, random, and transient. In each case, a cost function is defined and minimized for numerous parameter variations. For the case of harmonic excitation, the cost function is obtained by integrating the mean squared displacement over a region of the beam in which control is desired. A controller is then found to minimize this cost function in the control interval. The control interval and controller location are continuously varied for several frequencies of excitation. The results show that control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam, but control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, the cost function is realized by integrating the expected value of the displacement squared over the interval of the beam in which control is desired. This is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. A cost function representative of the beam vibration is obtained by integrating the transient displacement squared over a region of the beam and over all time. The form of the controller is chosen a priori as either one or two delayed pulses. Delays

  4. Transient Earth system responses to cumulative carbon dioxide emissions: linearities, uncertainties, and probabilities in an observation-constrained model ensemble

    NASA Astrophysics Data System (ADS)

    Steinacher, M.; Joos, F.

    2016-02-01

    Information on the relationship between cumulative fossil CO2 emissions and multiple climate targets is essential to design emission mitigation and climate adaptation strategies. In this study, the transient response of a climate or environmental variable per trillion tonnes of CO2 emissions, termed TRE, is quantified for a set of impact-relevant climate variables and from a large set of multi-forcing scenarios extended to year 2300 towards stabilization. An ˜ 1000-member ensemble of the Bern3D-LPJ carbon-climate model is applied and model outcomes are constrained by 26 physical and biogeochemical observational data sets in a Bayesian, Monte Carlo-type framework. Uncertainties in TRE estimates include both scenario uncertainty and model response uncertainty. Cumulative fossil emissions of 1000 Gt C result in a global mean surface air temperature change of 1.9 °C (68 % confidence interval (c.i.): 1.3 to 2.7 °C), a decrease in surface ocean pH of 0.19 (0.18 to 0.22), and a steric sea level rise of 20 cm (13 to 27 cm until 2300). Linearity between cumulative emissions and transient response is high for pH and reasonably high for surface air and sea surface temperatures, but less pronounced for changes in Atlantic meridional overturning, Southern Ocean and tropical surface water saturation with respect to biogenic structures of calcium carbonate, and carbon stocks in soils. The constrained model ensemble is also applied to determine the response to a pulse-like emission and in idealized CO2-only simulations. The transient climate response is constrained, primarily by long-term ocean heat observations, to 1.7 °C (68 % c.i.: 1.3 to 2.2 °C) and the equilibrium climate sensitivity to 2.9 °C (2.0 to 4.2 °C). This is consistent with results by CMIP5 models but inconsistent with recent studies that relied on short-term air temperature data affected by natural climate variability.

  5. A rapid, extensive, and transient transcriptional response to estrogen signaling in breast cancer cells.

    PubMed

    Hah, Nasun; Danko, Charles G; Core, Leighton; Waterfall, Joshua J; Siepel, Adam; Lis, John T; Kraus, W Lee

    2011-05-13

    We report the immediate effects of estrogen signaling on the transcriptome of breast cancer cells using global run-on and sequencing (GRO-seq). The data were analyzed using a new bioinformatic approach that allowed us to identify transcripts directly from the GRO-seq data. We found that estrogen signaling directly regulates a strikingly large fraction of the transcriptome in a rapid, robust, and unexpectedly transient manner. In addition to protein-coding genes, estrogen regulates the distribution and activity of all three RNA polymerases and virtually every class of noncoding RNA that has been described to date. We also identified a large number of previously undetected estrogen-regulated intergenic transcripts, many of which are found proximal to estrogen receptor binding sites. Collectively, our results provide the most comprehensive measurement of the primary and immediate estrogen effects to date and a resource for understanding rapid signal-dependent transcription in other systems.

  6. 3-D transient hydraulic tomography in unconfined aquifers with fast drainage response

    NASA Astrophysics Data System (ADS)

    Cardiff, M.; Barrash, W.

    2011-12-01

    We investigate, through numerical experiments, the viability of three-dimensional transient hydraulic tomography (3DTHT) for identifying the spatial distribution of groundwater flow parameters (primarily, hydraulic conductivity K) in permeable, unconfined aquifers. To invert the large amount of transient data collected from 3DTHT surveys, we utilize an iterative geostatistical inversion strategy in which outer iterations progressively increase the number of data points fitted and inner iterations solve the quasi-linear geostatistical formulas of Kitanidis. In order to base our numerical experiments around realistic scenarios, we utilize pumping rates, geometries, and test lengths similar to those attainable during 3DTHT field campaigns performed at the Boise Hydrogeophysical Research Site (BHRS). We also utilize hydrologic parameters that are similar to those observed at the BHRS and in other unconsolidated, unconfined fluvial aquifers. In addition to estimating K, we test the ability of 3DTHT to estimate both average storage values (specific storage Ss and specific yield Sy) as well as spatial variability in storage coefficients. The effects of model conceptualization errors during unconfined 3DTHT are investigated including: (1) assuming constant storage coefficients during inversion and (2) assuming stationary geostatistical parameter variability. Overall, our findings indicate that estimation of K is slightly degraded if storage parameters must be jointly estimated, but that this effect is quite small compared with the degradation of estimates due to violation of "structural" geostatistical assumptions. Practically, we find for our scenarios that assuming constant storage values during inversion does not appear to have a significant effect on K estimates or uncertainty bounds.

  7. 3-D Transient Hydraulic Tomography in Unconfined Aquifers with Fast Drainage Response

    SciTech Connect

    Cardiff, Michael A.; Barrash, Warren

    2011-12-16

    We investigate, through numerical experiments, the viability of three-dimensional transient hydraulic tomography (3DTHT) for identifying the spatial distribution of groundwater flow parameters (primarily, hydraulic conductivity K) in permeable, unconfined aquifers. To invert the large amount of transient data collected from 3DTHT surveys, we utilize an iterative geostatistical inversion strategy in which outer iterations progressively increase the number of data points fitted and inner iterations solve the quasilinear geostatistical formulas of Kitanidis. In order to base our numerical experiments around realistic scenarios, we utilize pumping rates, geometries, and test lengths similar to those attainable during 3DTHT field campaigns performed at the Boise Hydrogeophysical Research Site (BHRS). We also utilize hydrologic parameters that are similar to those observed at the BHRS and in other unconsolidated, unconfined fluvial aquifers. In addition to estimating K, we test the ability of 3DTHT to estimate both average storage values (specific storage Ss and specific yield Sy) as well as spatial variability in storage coefficients. The effects of model conceptualization errors during unconfined 3DTHT are investigated including: (1) assuming constant storage coefficients during inversion and (2) assuming stationary geostatistical parameter variability. Overall, our findings indicate that estimation of K is slightly degraded if storage parameters must be jointly estimated, but that this effect is quite small compared with the degradation of estimates due to violation of ‘‘structural’’ geostatistical assumptions. Practically, we find for our scenarios that assuming constant storage values during inversion does not appear to have a significant effect on K estimates or uncertainty bounds.

  8. Assessing the implications of human land-use change for the transient climate response to cumulative carbon emissions

    NASA Astrophysics Data System (ADS)

    Simmons, C. T.; Matthews, H. D.

    2016-03-01

    Recent research has shown evidence of a linear climate response to cumulative CO2 emissions, which implies that the source, timing, and amount of emissions does not significantly influence the climate response per unit emission. Furthermore, these analyses have generally assumed that the climate response to land-use CO2 emissions is equivalent to that of fossil fuels under the assumption that, once in the atmosphere, the radiative forcing induced by CO2 is not sensitive to the emissions source. However, land-cover change also affects surface albedo and the strength of terrestrial carbon sinks, both of which have an additional climate effect. In this study, we use a coupled climate-carbon cycle model to assess the climate response to historical and future cumulative land-use CO2 emissions, in order to compare it to the response to fossil fuel CO2. We find that when we isolate the CO2-induced (biogeochemical) temperature changes associated with land-use change, then the climate response to cumulative land-use emissions is equivalent to that of fossil fuel CO2. We show further that the globally-averaged albedo-induced biophysical cooling from land-use change is non-negligible and may be of comparable magnitude to the biogeochemical warming, with the result that the net climate response to land-use change is substantially different from a linear response to cumulative emissions. However, our new simulations suggest that the biophysical cooling from land-use change follows its own independent (negative) linear response to cumulative net land-use CO2 emissions, which may provide a useful scaling factor for certain applications when evaluating the full transient climate response to emissions.

  9. Transcriptional 'memory' of a stress: transient chromatin and memory (epigenetic) marks at stress-response genes.

    PubMed

    Avramova, Zoya

    2015-07-01

    Drought, salinity, extreme temperature variations, pathogen and herbivory attacks are recurring environmental stresses experienced by plants throughout their life. To survive repeated stresses, plants provide responses that may be different from their response during the first encounter with the stress. A different response to a similar stress represents the concept of 'stress memory'. A coordinated reaction at the organismal, cellular and gene/genome levels is thought to increase survival chances by improving the plant's tolerance/avoidance abilities. Ultimately, stress memory may provide a mechanism for acclimation and adaptation. At the molecular level, the concept of stress memory indicates that the mechanisms responsible for memory-type transcription during repeated stresses are not based on repetitive activation of the same response pathways activated by the first stress. Some recent advances in the search for transcription 'memory factors' are discussed with an emphasis on super-induced dehydration stress memory response genes in Arabidopsis.

  10. Optical studies of the X-ray transient XTE J2123-058 - II. Phase-resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Hynes, R. I.; Charles, P. A.; Haswell, C. A.; Casares, J.; Zurita, C.; Serra-Ricart, M.

    2001-06-01

    We present time-resolved spectroscopy of the soft X-ray transient XTEJ2123-058 in outburst. A useful spectral coverage of 3700-6700Å was achieved spanning two orbits of the binary, with single-epoch coverage extending to ~9000Å. The optical spectrum approximates a steep blue power law, consistent with emission on the Rayleigh-Jeans tail of a hot blackbody spectrum. The strongest spectral lines are Heii 4686Å and Ciii/Niii 4640Å (Bowen blend) in emission. Their relative strengths suggest that XTEJ2123-058 was formed in the Galactic plane, not in the halo. Other weak emission lines of Heii and Civ are present, and Balmer lines show a complex structure, blended with Heii. Heii 4686-Å profiles show a complex multiple S-wave structure, with the strongest component appearing at low velocities in the lower-left quadrant of a Doppler tomogram. Hα shows transient absorption between phases 0.35 and 0.55. Both of these effects appear to be analogous to similar behaviour in SW Sex type cataclysmic variables. We therefore consider whether the spectral line behaviour of XTEJ2123-058 can be explained by the same models invoked for those systems.

  11. Finite-element nonlinear transient response computer programs PLATE 1 and CIVM-PLATE 1 for the analysis of panels subjected to impulse or impact loads

    NASA Technical Reports Server (NTRS)

    Spilker, R. L.; Witmer, E. A.; French, S. E.; Rodal, J. J. A.

    1980-01-01

    Two computer programs are described for predicting the transient large deflection elastic viscoplastic responses of thin single layer, initially flat unstiffened or integrally stiffened, Kirchhoff-Lov ductile metal panels. The PLATE 1 program pertains to structural responses produced by prescribed externally applied transient loading or prescribed initial velocity distributions. The collision imparted velocity method PLATE 1 program concerns structural responses produced by impact of an idealized nondeformable fragment. Finite elements are used to represent the structure in both programs. Strain hardening and strain rate effects of initially isotropic material are considered.

  12. Transient and sustained increases in inositol 1,4,5-trisphosphate precede the differential growth response in gravistimulated maize pulvini

    NASA Technical Reports Server (NTRS)

    Perera, I. Y.; Heilmann, I.; Boss, W. F.; Davies, E. (Principal Investigator)

    1999-01-01

    The internodal maize pulvinus responds to gravistimulation with differential cell elongation on the lower side. As the site of both graviperception and response, the pulvinus is an ideal system to study how organisms sense changes in orientation. We observed a transient 5-fold increase in inositol 1,4,5-trisphosphate (IP3) within 10 s of gravistimulation in the lower half of the pulvinus, indicating that the positional change was sensed immediately. Over the first 30 min, rapid IP3 fluctuations were observed between the upper and lower halves. Maize plants require a presentation time of between 2 and 4 h before the cells on the lower side of the pulvinus are committed to elongation. After 2 h of gravistimulation, the lower half consistently had higher IP3, and IP3 levels on the lower side continued to increase up to approximately 5-fold over basal levels before visible growth. As bending became visible after 8-10 h, IP3 levels returned to basal values. Additionally, phosphatidylinositol 4-phosphate 5-kinase activity in the lower pulvinus half increased transiently within 10 min of gravistimulation, suggesting that the increased IP3 production was accompanied by an up-regulation of phosphatidylinositol 4, 5-bisphosphate biosynthesis. Neither IP3 levels nor phosphatidylinositol 4-phosphate 5-kinase activity changed in pulvini halves from vertical control plants. Our data indicate the involvement of IP3 and inositol phospholipids in both short- and long-term responses to gravistimulation. As a diffusible second messenger, IP3 provides a mechanism to transmit and amplify the signal from the perceiving to the responding cells in the pulvinus, coordinating a synchronized growth response.

  13. Frontal brain asymmetry and transient cardiovascular responses to the perception of humor.

    PubMed

    Papousek, Ilona; Schulter, Günter; Weiss, Elisabeth M; Samson, Andrea C; Freudenthaler, H Harald; Lackner, Helmut K

    2013-04-01

    The study examined the relationship of individual differences in prefrontal brain asymmetry, measured by the EEG in resting conditions, to the individual's responsivity in the context of humor (n=42). Several weeks after the EEG recording, immediate cardiovascular responses to the perception of humor and behavioral indicators of humor processing were obtained in an experimental paradigm involving non-verbal cartoons. Relatively greater resting activity in the left than right prefrontal cortex, particularly at the ventrolateral positions, was associated with faster detection of humor, a more pronounced cardiac response to the perception of humor (heart rate and cardiac output), and more accessible internal positive affective states (indicated by faster reports of amusement levels). The study confirms and extends findings of the relevance of prefrontal brain asymmetry to affective responsivity, contributing evidence in the domain of positive affect and humor, and demonstrating relationships to the immediate cardiovascular response pattern to an emotional event.

  14. Hardware-Based Simulation of a Fuel Cell Turbine Hybrid Response to Imposed Fuel Cell Load Transients

    SciTech Connect

    Smith, T.P.; Tucker, D.A.; Haynes, C.L.; Liese, E.A.; Wepfer, W.J.

    2006-11-01

    Electrical load transients imposed on the cell stack of a solid oxide fuel cell/gas turbine hybrid power system are studied using the Hybrid Performance (HyPer) project. The hardware simulation facility is located at the U.S. Department of Energy, National Energy Technology Laboratory (NETL). A computational fuel cell model capable of operating in real time is integrated with operating gas turbine hardware. The thermal output of a modeled 350 kW solid oxide fuel cell stack is replicated in the facility by a natural gas fired burner in a direct fired hybrid configuration. Pressure vessels are used to represent a fuel cell stack's cathode flow and post combustion volume and flow impedance. This hardware is used to simulate the fuel cell stack and is incorporated with a modified turbine, compressor, and 120 kW generator on a single shaft. For this study, a simulation was started with a simulated current demand of 307 A on the fuel cell at approximately 0.75 V and an actual 45 kW electrical load on the gas turbine. An open loop response, allowing the turbine rotational speed to respond to thermal transients, was successfully evaluated for a 5% current reduction on the fuel cell followed by a 5% current increase. The impact of the fuel cell load change on system process variables is presented. The test results demonstrate the capabilities of the hardware-in-the-loop simulation approach in evaluating hybrid fuel cell turbine dynamics and performance.

  15. Non-invasive near-infrared fluorescence imaging of the neutrophil response in a mouse model of transient cerebral ischaemia.

    PubMed

    Vaas, Markus; Enzmann, Gaby; Perinat, Therese; Siler, Ulrich; Reichenbach, Janine; Licha, Kai; Kipar, Anja; Rudin, Markus; Engelhardt, Britta; Klohs, Jan

    2016-10-27

    Near-infrared fluorescence (NIRF) imaging enables non-invasive monitoring of molecular and cellular processes in live animals. Here we demonstrate the suitability of NIRF imaging to investigate the neutrophil response in the brain after transient middle cerebral artery occlusion (tMCAO). We established procedures for ex vivo fluorescent labelling of neutrophils without affecting their activation status. Adoptive transfer of labelled neutrophils in C57BL/6 mice before surgery resulted in higher fluorescence intensities over the ischaemic hemisphere in tMCAO mice with NIRF imaging when compared with controls, corroborated by ex vivo detection of labelled neutrophils using fluorescence microscopy. NIRF imaging showed that neutrophils started to accumulate immediately after tMCAO, peaking at 18 h, and were still visible until 48 h after reperfusion. Our data revealed accumulation of neutrophils also in extracranial tissue, indicating damage in the external carotid artery territory in the tMCAO model. Antibody-mediated inhibition of α4-integrins did reduce fluorescence signals at 18 and 24, but not at 48 h after reperfusion, compared with control treatment animals. Antibody treatment reduced cerebral lesion volumes by 19%. In conclusion, the non-invasive nature of NIRF imaging allows studying the dynamics of neutrophil recruitment and its modulation by targeted interventions in the mouse brain after transient experimental cerebral ischaemia.

  16. Ultrafast electronic response of Ag(111) and Cu(111) surfaces: From early excitonic transients to saturated image potential

    NASA Astrophysics Data System (ADS)

    Silkin, V. M.; Lazić, P.; Došlić, N.; Petek, H.; Gumhalter, B.

    2015-10-01

    We investigate the evolution of attosecond to femtosecond screening and emergent potentials that govern the dynamics and energetics of electrons and holes excited in the various stages of multiphoton photoemission processes and control the photoelectron yield in recently reported experiments [X. Cui, C. Wang, A. Argondizzo, S. Garrett-Roe, B. Gumhalter, and H. Petek, Nat. Phys. 10, 505 (2014), 10.1038/nphys2981]. The study is focused on the dynamical screening of holes created in preexistent quasi-two-dimensional Shockley state bands on Ag(111) and Cu(111) surfaces and of electrons excited to the intermediate and emerging screened states. Using the formalism of self-consistent electronic response, we analyze first the effects of screening on the dynamics of photoexcited electrons and holes and then of the Coulomb correlated photoexcited pair. Special attention is paid to the correlated primary electron-hole states, which commence as transient surface excitons and develop in the course of screening into uncorrelated electrons and holes propagating in the image potential and surface state bands, respectively. The obtained results enable to establish a consistent picture of transient electron dynamics at Ag(111) and Cu(111) surfaces that are becoming accessible by the time-, energy-, and momentum-resolved pump-probe multiphoton photoelectron spectroscopies.

  17. Transient α-helices in the disordered RPEL motifs of the serum response factor coactivator MKL1

    NASA Astrophysics Data System (ADS)

    Mizuguchi, Mineyuki; Fuju, Takahiro; Obita, Takayuki; Ishikawa, Mitsuru; Tsuda, Masaaki; Tabuchi, Akiko

    2014-06-01

    The megakaryoblastic leukemia 1 (MKL1) protein functions as a transcriptional coactivator of the serum response factor. MKL1 has three RPEL motifs (RPEL1, RPEL2, and RPEL3) in its N-terminal region. MKL1 binds to monomeric G-actin through RPEL motifs, and the dissociation of MKL1 from G-actin promotes the translocation of MKL1 to the nucleus. Although structural data are available for RPEL motifs of MKL1 in complex with G-actin, the structural characteristics of RPEL motifs in the free state have been poorly defined. Here we characterized the structures of free RPEL motifs using NMR and CD spectroscopy. NMR and CD measurements showed that free RPEL motifs are largely unstructured in solution. However, NMR analysis identified transient α-helices in the regions where helices α1 and α2 are induced upon binding to G-actin. Proline mutagenesis showed that the transient α-helices are locally formed without helix-helix interactions. The helix content is higher in the order of RPEL1, RPEL2, and RPEL3. The amount of preformed structure may correlate with the binding affinity between the intrinsically disordered protein and its target molecule.

  18. Transient Receptor Potential Melastatin-3 (TRPM3) Mediates Nociceptive-Like Responses in Hydra vulgaris

    PubMed Central

    Malafoglia, Valentina; Traversetti, Lorenzo; Del Grosso, Floriano; Scalici, Massimiliano; Lauro, Filomena; Russo, Valeria; Persichini, Tiziana; Salvemini, Daniela; Mollace, Vincenzo; Fini, Massimo; Raffaeli, William

    2016-01-01

    The ability of mammals to feel noxious stimuli lies in a heterogeneous group of primary somatosensory neurons termed nociceptors, which express specific membrane receptors, such as the Transient Receptor Potential (TRP) family. Here, we show that one of the most important nociceptive-like pathways is conserved in the freshwater coelenterate Hydra vulgaris, the most primitive organism possessing a nervous system. In particular, we found that H. vulgaris expresses TRPM3, a nociceptor calcium channel involved in the detection of noxious heat in mammals. Furthermore, we detected that both heat shock and TRPM3 specific agonist (i.e., pregnenolone sulfate) induce the modulation of the heat shock protein 70 (HSP70) and the nitric oxide synthase (NOS), two genes activated by TRP-mediated heat painful stimuli in mammals. As expected, these effects are inhibited by a TRPM3 antagonist (i.e., mefenamic acid). Interestingly, the TRPM3 agonist and heat shock also induce the expression of nuclear transcription erythroid 2-related factor (Nrf2) and superoxide dismutase (SOD), known markers of oxidative stress; noteworthy gene expression was also inhibited by the TRPM3 antagonist. As a whole, our results demonstrate the presence of conserved molecular oxidative/nociceptive-like pathways at the primordial level of the animal kingdom. PMID:26974325

  19. Transient Receptor Potential Melastatin-3 (TRPM3) Mediates Nociceptive-Like Responses in Hydra vulgaris.

    PubMed

    Malafoglia, Valentina; Traversetti, Lorenzo; Del Grosso, Floriano; Scalici, Massimiliano; Lauro, Filomena; Russo, Valeria; Persichini, Tiziana; Salvemini, Daniela; Mollace, Vincenzo; Fini, Massimo; Raffaeli, William; Muscoli, Carolina; Colasanti, Marco

    2016-01-01

    The ability of mammals to feel noxious stimuli lies in a heterogeneous group of primary somatosensory neurons termed nociceptors, which express specific membrane receptors, such as the Transient Receptor Potential (TRP) family. Here, we show that one of the most important nociceptive-like pathways is conserved in the freshwater coelenterate Hydra vulgaris, the most primitive organism possessing a nervous system. In particular, we found that H. vulgaris expresses TRPM3, a nociceptor calcium channel involved in the detection of noxious heat in mammals. Furthermore, we detected that both heat shock and TRPM3 specific agonist (i.e., pregnenolone sulfate) induce the modulation of the heat shock protein 70 (HSP70) and the nitric oxide synthase (NOS), two genes activated by TRP-mediated heat painful stimuli in mammals. As expected, these effects are inhibited by a TRPM3 antagonist (i.e., mefenamic acid). Interestingly, the TRPM3 agonist and heat shock also induce the expression of nuclear transcription erythroid 2-related factor (Nrf2) and superoxide dismutase (SOD), known markers of oxidative stress; noteworthy gene expression was also inhibited by the TRPM3 antagonist. As a whole, our results demonstrate the presence of conserved molecular oxidative/nociceptive-like pathways at the primordial level of the animal kingdom.

  20. Low Stretch Solid-Fuel Flame Transient Response to a Step Change in Gravity

    NASA Technical Reports Server (NTRS)

    Armstrong, J. B.; Olson, S. L.; T'ien, J. S.

    2003-01-01

    The effect of a step change in gravity level on the stability of low stretch diffusion flames over a solid fuel is studied both numerically and experimentally. Drop tower experiments have been conducted in NASA Glenn Research Center's 5.2 Zero Gravity Facility. In the experiments burning PMMA cylinders, a dynamic transition is observed when the steadily burning 1g flame is dropped and becomes a 0g flame. To understand the physics behind this dynamic transition, a transient stagnation point model has been developed which includes gas-phase radiation and solid phase coupling to describe this dynamic process. In this paper, the experimental results are compared with the model predictions. Both model and experiment show that the interior of the solid phase does not have time to change significantly in the few seconds of drop time, so the experimental results are pseudo-steady in the gas-phase, but the solid is inherently unsteady over long time scales. The model is also used to examine the importance of fractional heat losses on extinction, which clearly demonstrates that as the feedback from the flame decreases, the importance of the ongoing heat losses becomes greater, and extinction is observed when these losses represent 80% or more of the flame feedback.

  1. Thermal and power availability transient responses for the Argonne monolithic solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Hanan, Nelson A.; Carlson, Larry W.

    The Monolithic solid oxide fuel cell (SOFC) is a candidate electric power source for space applications which require multimegawatts within short startup times. In a previous systems study, an SOFC was coupled to a nuclear Rankine cycle to provide both long term housekeeping power, short term alert power, and shorter term burst power. Waste heat from the nuclear system was used to maintain the SOFC components at an elevated initial temperature. Despite this provision, it was not known whether the SOFC would provide required power levels within the especially short time frame demanded by the application. A finite difference transient thermal analysis, coupled with the electrochemical equations, was done using the Dusinberre methodology. The Argonne Monolithic fuel cell construction consists of a corrugated sandwich of anode, electrolyte, and cathode elements alternating with a sandwich of anode, interconnection, and cathode materials in a multilayer structure. Electrical potential develops across the anode-electrolyte-cathode sandwich and builds in the layered direction. The interconnection material permits electron transport, but blocks oxygen ion back diffusion, which otherwise would short out the cell.

  2. Emergence of Hysteresis and Transient Ferroelectric Response in Organo-Lead Halide Perovskite Solar Cells.

    PubMed

    Chen, Hsin-Wei; Sakai, Nobuya; Ikegami, Masashi; Miyasaka, Tsutomu

    2015-01-02

    Although there has been rapid progress in the efficiency of perovskite-based solar cells, hysteresis in the current-voltage performance is not yet completely understood. Owing to its complex structure, it is not easy to attribute the hysteretic behavior to any one of different components, such as the bulk of the perovskite or different heterojunction interfaces. Among organo-lead halide perovskites, methylammonium lead iodide perovskite (CH3NH3PbI3) is known to have a ferroelectric property. The present investigation reveals a strong correlation between transient ferroelectric polarization of CH3NH3PbI3 induced by an external bias in the dark and hysteresis enhancement in photovoltaic characteristics. Our results demonstrate that the reverse bias poling (-0.3 to -1.1 V) of CH3NH3PbI3 photovoltaic layers prior to the photocurrent-voltage measurement generates stronger hysteresis whose extent changes significantly by the cell architecture. The phenomenon is interpreted as the effect of remanent polarization in the perovskite film on the photocurrent, which is most enhanced in planar perovskite structures without mesoporous scaffolds.

  3. Modeling the hydrologic response of groundwater dominated wetlands to transient boundary conditions: Implications for wetland restoration

    NASA Astrophysics Data System (ADS)

    Boswell, James S.; Olyphant, Greg A.

    2007-01-01

    SummaryA variably-saturated groundwater model, based on that of Freeze [Freeze, R.A., 1971. Three-dimensional, transient, saturated-unsaturated flow in a groundwater basin. Water Resources Research 7, 347-366.], was used to analyze the details of surface-groundwater interaction and resulting hydroperiods of a site undergoing wetland restoration (the Lake Station Wetland Restoration Site in Northwest Indiana, USA). The three-dimensional groundwater flow model couples the saturated and unsaturated zones through the use of van Genuchten's [van Genuchten, M.T., 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal 44, 892-898.] characteristic equations. Initial estimates of hydraulic parameters were refined through a calibration exercise aimed at minimizing the discrepancy between simulated and measured water levels in seven wells within the study. Numerical simulations using the calibrated model, and driven by annual time series of rainfall and potential evaporation, were used to generate hydroperiod maps of surface saturation and root-zone saturation over a three-year period of study. This allowed identification of regularly saturated areas that would support hydric plants, as well as more rarely saturated areas that would require more dry tolerant species or additional hydrological remediation. The simulations also revealed the critical roles that topography, rainfall history, and antecedent conditions play in the hydrology of degraded wetlands that have been targeted for restoration.

  4. Transient Raman response and soliton self-frequency shift in tellurite microstructured fiber

    NASA Astrophysics Data System (ADS)

    Yan, Xin; Qin, Guanshi; Liao, Meisong; Suzuki, Takenobu; Ohishi, Yasutake

    2010-12-01

    We report on the Raman response function and the soliton self-frequency shift in a tellurite microstructured fiber pumped at 1557 nm. The Raman response function in a tellurite fiber quantifies a contribution of the Raman fraction to the nonlinear optical response. Continuous soliton wavelength shift from 1582 to 1851 nm is observed in a tellurite microstructured optical fiber with the length of 6.5 cm. The experimental results strongly correlated with the numerical simulations based on a generalized nonlinear Schrödinger equation.

  5. LUNAR OUTGASSING, TRANSIENT PHENOMENA, AND THE RETURN TO THE MOON. II. PREDICTIONS AND TESTS FOR OUTGASSING/REGOLITH INTERACTIONS

    SciTech Connect

    Crotts, Arlin P. S.; Hummels, Cameron

    2009-12-20

    We follow Paper I with predictions of how gas leaking through the lunar surface could influence the regolith, as might be observed via optical transient lunar phenomena (TLPs) and related effects. We touch on several processes, but concentrate on low and high flow rate extremes, which are perhaps the most likely. We model explosive outgassing for the smallest gas overpressure at the regolith base that releases the regolith plug above it. This disturbance's timescale and affected area are consistent with observed TLPs; we also discuss other effects. For slow flow, escape through the regolith is prolonged by low diffusivity. Water, found recently in deep magma samples, is unique among candidate volatiles, capable of freezing between the regolith base and surface, especially near the lunar poles. For major outgassing sites, we consider the possible accumulation of water ice. Over geological time, ice accumulation can evolve downward through the regolith. Depending on gases additional to water, regolith diffusivity might be suppressed chemically, blocking seepage and forcing the ice zone to expand to larger areas, up to km{sup 2} scales, again, particularly at high latitudes. We propose an empirical path forward, wherein current and forthcoming technologies provide controlled, sensitive probes of outgassing. The optical transient/outgassing connection, addressed via Earth-based remote sensing, suggests imaging and/or spectroscopy, but aspects of lunar outgassing might be more covert, as indicated above. TLPs betray some outgassing, but does outgassing necessarily produce TLPs? We also suggest more intrusive techniques from radar to in situ probes. Understanding lunar volatiles seems promising in terms of resource exploitation for human exploration of the Moon and beyond, and offers interesting scientific goals in its own right. Many of these approaches should be practiced in a pristine lunar atmosphere, before significant confusing signals likely to be produced upon

  6. Alcohol delays the emergence of the fetal elicited startle response, but only transiently.

    PubMed

    Hepper, Peter G; Dornan, James C; Lynch, Catherine; Maguire, Jennifer F

    2012-08-20

    Prenatal exposure to alcohol may exert a significant detrimental effect on the functioning of the individual's brain, however few studies have examined this before birth. This longitudinal study examined the effect of maternal alcohol consumption on the elicited startle response of the fetus. Two groups of fetuses were examined: one whose mothers drank alcohol (approximately 10 units per week); the other whose mothers did not drink alcohol. Fetuses were examined at 29, 32 and 35 weeks gestation and their startle response observed using ultrasound in response to 2 presentations of a pink noise (70-250Hz) at 90dB(A) separated by 30s. Fetuses exposed to alcohol exhibited a weaker startle response at 29 weeks gestation than did fetuses not exposed to alcohol. There was no difference in the response at 32 and 35 weeks gestation. To ensure that the effects were not due to a more general effect of alcohol on fetal movement, a second experiment compared the spontaneous movements (observed on ultrasound for 45 min) of fetuses whose mothers drank alcohol and fetuses of mothers who didn't drink alcohol. There were no differences in movements exhibited by the fetuses. The results suggest that exposure to alcohol delays the emergence of the elicited startle response at 29 weeks gestation but this delay has disappeared by 32 weeks gestation. The possible role of altered neural development, acute exposure to alcohol and disruptions to the fetus's behavioural repertoire, in mediating these effects are discussed.

  7. Transient Thermal Response of Lightweight Cementitious Composites Made with Polyurethane Foam Waste

    NASA Astrophysics Data System (ADS)

    Kismi, M.; Poullain, P.; Mounanga, P.

    2012-07-01

    The development of low-cost lightweight aggregate (LWA) mortars and concretes presents many advantages, especially in terms of lightness and thermal insulation performances of structures. Low-cost LWA mainly comes from the recovery of vegetal or plastic wastes. This article focuses on the characterization of the thermal conductivity of innovative lightweight cementitious composites made with fine particles of rigid polyurethane (PU) foam waste. Five mortars were prepared with various mass substitution rates of cement with PU-foam particles. Their thermal conductivity was measured with two transient methods: the heating-film method and the hot-disk method. The incorporation of PU-foam particles causes a reduction of up to 18 % of the mortar density, accompanied by a significant improvement of the thermal insulating performance. The effect of segregation on the thermal properties of LWA mortars due to the differences of density among the cementitious matrix, sand, and LWA has also been quantified. The application of the hot-disk method reveals a gradient of thermal conductivity along the thickness of the specimens, which could be explained by a non-uniform repartition of fine PU-foam particles and mineral aggregates within the mortars. The results show a spatial variation of the thermal conductivity of the LWA mortars, ranging from 9 % to 19 %. However, this variation remains close to or even lower than that observed on a normal weight aggregate mortar. Finally, a self-consistent approach is proposed to estimate the thermal conductivity of PU-foam cement-based composites.

  8. Transient and steady state creep response of ice I and magnesium sulfate hydrate eutectic aggregates

    USGS Publications Warehouse

    McCarthy, C.; Cooper, R.F.; Goldsby, D.L.; Durham, W.B.; Kirby, S.H.

    2011-01-01

    Using uniaxial compression creep experiments, we characterized the transient and steady state deformation behaviors of eutectic aggregates of system ice I and MgSO4 11H2O (MS11; meridianiite), which has significance because of its likely presence on moons of the outer solar system. Synthetic samples of eutectic liquid bulk composition, which produce eutectic colonies containing 0.35-0.50 volume fraction MS11, were tested as functions of colony size and lamellar spacing, temperature (230-250 K), and confining pressure (0.1 and 50 MPa) to strains ???0.2. Up to a differential stress of 6 MPa, the ice I-MS11 aggregates display an order of magnitude higher effective viscosity and higher stress sensitivity than do aggregates of pure polycrystalline ice at the same conditions. The creep data and associated microstructural observations demonstrate, however, that the aggregates are additionally more brittle than pure ice, approaching rate-independent plasticity that includes rupture of the hydrate phase at 6-8 MPa, depending on the scale of the microstructure. Microstructures of deformed samples reveal forms of semibrittle flow in which the hydrate phase fractures while the ice phase deforms plastically. Semibrittle flow in the icy shell of a planetary body would truncate the lithospheric strength envelope and thereby decrease the depth to the brittle-ductile transition by 55% and reduce the failure limit for compressional surface features from 10 to ???6 MPa. A constitutive equation that includes eutectic colony boundary sliding and intracolony flow is used to describe the steady state rheology of the eutectic aggregates. Copyright ?? 2011 by the American Geophysical Union.

  9. Transient and steady state creep response of ice I and magnesium sulfate hydrate eutectic aggregates

    NASA Astrophysics Data System (ADS)

    McCarthy, Christine; Cooper, Reid F.; Goldsby, David L.; Durham, William B.; Kirby, Stephen H.

    2011-04-01

    Using uniaxial compression creep experiments, we characterized the transient and steady state deformation behaviors of eutectic aggregates of system ice I and MgSO4 • 11H2O (MS11; meridianiite), which has significance because of its likely presence on moons of the outer solar system. Synthetic samples of eutectic liquid bulk composition, which produce eutectic colonies containing 0.35-0.50 volume fraction MS11, were tested as functions of colony size and lamellar spacing, temperature (230-250 K), and confining pressure (0.1 and 50 MPa) to strains ≤ 0.2. Up to a differential stress of 6 MPa, the ice I-MS11 aggregates display an order of magnitude higher effective viscosity and higher stress sensitivity than do aggregates of pure polycrystalline ice at the same conditions. The creep data and associated microstructural observations demonstrate, however, that the aggregates are additionally more brittle than pure ice, approaching rate-independent plasticity that includes rupture of the hydrate phase at 6-8 MPa, depending on the scale of the microstructure. Microstructures of deformed samples reveal forms of semibrittle flow in which the hydrate phase fractures while the ice phase deforms plastically. Semibrittle flow in the icy shell of a planetary body would truncate the lithospheric strength envelope and thereby decrease the depth to the brittle-ductile transition by 55% and reduce the failure limit for compressional surface features from 10 to ˜6 MPa. A constitutive equation that includes eutectic colony boundary sliding and intracolony flow is used to describe the steady state rheology of the eutectic aggregates.

  10. Finite-strain large-deflection elastic-viscoplastic finite-element transient response analysis of structures

    NASA Technical Reports Server (NTRS)

    Rodal, J. J. A.; Witmer, E. A.

    1979-01-01

    A method of analysis for thin structures that incorporates finite strain, elastic-plastic, strain hardening, time dependent material behavior implemented with respect to a fixed configuration and is consistently valid for finite strains and finite rotations is developed. The theory is formulated systematically in a body fixed system of convected coordinates with materially embedded vectors that deform in common with continuum. Tensors are considered as linear vector functions and use is made of the dyadic representation. The kinematics of a deformable continuum is treated in detail, carefully defining precisely all quantities necessary for the analysis. The finite strain theory developed gives much better predictions and agreement with experiment than does the traditional small strain theory, and at practically no additional cost. This represents a very significant advance in the capability for the reliable prediction of nonlinear transient structural responses, including the reliable prediction of strains large enough to produce ductile metal rupture.

  11. Transient Response of Arc Temperature and Iron Vapor Concentration Affected by Current Frequency with Iron Vapor in Pulsed Arc

    NASA Astrophysics Data System (ADS)

    Tanaka, Tatsuro; Maeda, Yoshifumi; Yamamoto, Shinji; Iwao, Toru

    2016-10-01

    TIG arc welding is chemically a joining technology with melting the metallic material and it can be high quality. However, this welding should not be used in high current to prevent cathode melting. Thus, the heat transfer is poor. Therefore, the deep penetration cannot be obtained and the weld defect sometimes occurs. The pulsed arc welding has been used for the improvement of this defect. The pulsed arc welding can control the heat flux to anode. The convention and driving force in the weld pool are caused by the arc. Therefore, it is important to grasp the distribution of arc temperature. The metal vapor generate from the anode in welding. In addition, the pulsed current increased or decreased periodically. Therefore, the arc is affected by such as a current value and current frequency, the current rate of increment and the metal vapor. In this paper, the transient response of arc temperature and the iron vapor concentration affected by the current frequency with iron vapor in pulsed arc was elucidated by the EMTF (ElectroMagnetic Thermal Fluid) simulation. As a result, the arc temperature and the iron vapor were transient response as the current frequency increase. Thus, the temperature and the electrical conductivity decreased. Therefore, the electrical field increased in order to maintain the current continuity. The current density and electromagnetic force increased at the axial center. In addition, the electronic flow component of the heat flux increased at the axial center because the current density increased. However, the heat conduction component of the heat flux decreased.

  12. A femtosecond visible/visible and visible/mid-infrared transient absorption study of the light harvesting complex II.

    PubMed

    Stahl, Andreas D; Di Donato, Mariangela; van Stokkum, Ivo; van Grondelle, Rienk; Groot, Marie Louise

    2009-12-16

    Light harvesting complex II (LHCII) is the most abundant protein in the thylakoid membrane of higher plants and green algae. LHCII acts to collect solar radiation, transferring this energy mainly toward photosystem II, with a smaller amount going to photosystem I; it is then converted into a chemical, storable form. We performed time-resolved femtosecond visible pump/mid-infrared probe and visible pump/visible probe absorption difference spectroscopy on purified LHCII to gain insight into the energy transfer in this complex occurring in the femto-picosecond time regime. We find that information derived from mid-infrared spectra, together with structural and modeling information, provides a unique visualization of the flow of energy via the bottleneck pigment chlorophyll a604.

  13. Nonlinear optical response of C60 in solvents: picosecond transient grating experiments

    NASA Astrophysics Data System (ADS)

    Khudyakov, Dmitriy V.; Rubtsov, Igor V.; Lobach, Anatolii S.; Nadtochenko, Victor A.

    1996-05-01

    Time-resolved resonant nonlinear optical response of C60 in a chlorobenzene solution was measured for 528 nm excitation and 1055, 528, and 351 nm probing for zzzz and zzyy configurations. The slow part of the signal (8 +/- 2 ps) was attributed to the orientational motion of C60 excited molecules.

  14. Effect of a misspecification of response rates on type I and type II errors, in a phase II Simon design.

    PubMed

    Baey, Charlotte; Le Deley, Marie-Cécile

    2011-07-01

    Phase-II trials are a key stage in the clinical development of a new treatment. Their main objective is to provide the required information for a go/no-go decision regarding a subsequent phase-III trial. In single arm phase-II trials, widely used in oncology, this decision relies on the comparison of efficacy outcomes observed in the trial to historical controls. The false positive rate generally accepted in phase-II trials, around 10%, contrasts with the very high attrition rate of new compounds tested in phase-III trials, estimated at about 60%. We assumed that this gap could partly be explained by the misspecification of the response rate expected with standard treatment, leading to erroneous hypotheses tested in the phase-II trial. We computed the false positive probability of a defined design under various hypotheses of expected efficacy probability. Similarly we calculated the power of the trial to detect the efficacy of a new compound for different expected efficacy rates. Calculations were done considering a binary outcome, such as the response rate, with a decision rule based on a Simon two-stage design. When analysing a single-arm phase-II trial, based on a design with a pre-specified null hypothesis, a 5% absolute error in the expected response rate leads to a false positive rate of about 30% when it is supposed to be 10%. This inflation of type-I error varies only slightly according to the hypotheses of the initial design. Single-arm phase-II trials poorly control for the false positive rate. Randomised phase-II trials should, therefore, be more often considered.

  15. Dendritic cell-based immunotherapy induces transient clinical response in advanced rat fibrosarcoma - comparison with preventive anti-tumour vaccination.

    PubMed

    Kucera, A; Pýcha, K; Pajer, P; Spísek, R; Skába, R

    2009-01-01

    In this study we present the models of preventive and therapeutic vaccination of sarcoma-bearing rats with dendritic cells that present tumour antigens from killed tumour cells. We present the characteristics of dendritic cell-based vaccine and its capacity to induce anti-tumour immune response both in vitro and in vivo. We show that preventive vaccination efficiently prevents tumour growth. On the other hand, vaccination of rats with established tumours did not lead to eradication of the tumours. Despite the induction of a vigorous immune response after administration of dendritic cell-based vaccine and transient decrease in tumour progression, tumours eventually resumed their growth and animals vaccinated with dendritic cells succumbed to cancer. In both settings, preventive and therapeutic, dendritic cell-based vaccination induced a vigorous tumour-specific T-cell response. These results argue for the timing of cancer immunotherapy to the stages of low tumour load. Immunotherapy initiated at the stage of minimal residual disease, after reduction of tumour load by other modalities, will have much better chance to offer a clinical benefit to cancer patients than the immunotherapy at the stage of metastatic disease.

  16. Transient receptor potential vanilloid-1-mediated calcium responses are inhibited by the alkylamine antihistamines dexbrompheniramine and chlorpheniramine.

    PubMed

    Sadofsky, Laura R; Campi, Barbara; Trevisani, Marcello; Compton, Steven J; Morice, Alyn H

    2008-12-01

    American guidelines, unlike European guidelines, support the use of antihistamines as a first line of treatment for some causes of chronic cough. Transient receptor potential vanilloid-1 (TRPV1) is an ion channel activated by the tussive agents capsaicin, resiniferatoxin, and protons. It is predominantly expressed by C-fiber and some Adelta -fiber sensory neurons and is thought to be a cough receptor. By measuring increases in intracellular calcium as an indicator of TRPV1 activation, the authors sought to determine whether antihistamines could antagonise TRPV1 permanently expressed in HEK and Pro5 cells and TRPV1 endogenously expressed in rat dorsal root ganglia neurons. In human TRPV1-expressing HEK cells (hTRPV1-HEK), diphenhydramine and fexofenadine failed to inhibit capsaicin-triggered calcium responses. However, both dexbrompheniramine and chlorpheniramine significantly inhibited capsaicin-evoked responses in hTRPV1-HEK. Dexbrompheniramine also inhibited activation of rat TRPV1 expressed in HEK and Pro5 cells, without interfering with TRPA1 and proteinase-activated receptor-2 (PAR(2)) activation. Finally, in rat dorsal root ganglia neuron preparations, dexbrompheniramine dose-dependently inhibited capsaicin-evoked calcium responses. Thus, the inhibition of TRPV1 activation by dexbrompheniramine may provide one potential mechanism whereby this antihistamine exerts its therapeutic effect in chronic cough.

  17. Biogeochemical Processes Responsible for the Enhanced Transport of Plutonium Under transient Unsaturated Ground Water Conditions

    SciTech Connect

    Fred J. Molz, III

    2010-05-28

    To better understand longer-term vadose zone transport in southeastern soils, field lysimeter experiments were conducted at the Savannah River Site (SRS) near Aiken, SC, in the 1980s. Each of the three lysimeters analyzed herein contained a filter paper spiked with different Pu solutions, and they were left exposed to natural environmental conditions (including the growth of annual weed grasses) for 11 years. The resulting Pu activity measurements from each lysimeter core showed anomalous activity distributions below the source, with significant migration of Pu above the source. Such results are not explainable by adsorption phenomena alone. A transient variably saturated flow model with root water uptake was developed and coupled to a soil reactive transport model. Somewhat surprisingly, the fully transient analysis showed results nearly identical to those of a much simpler steady flow analysis performed previously. However, all phenomena studied were unable to produce the upward Pu transport observed in the data. This result suggests another transport mechanism such as Pu uptake by roots and upward transport due to transpiration. Thus, the variably saturated flow and reactive transport model was extended to include uptake and transport of Pu within the root xylem, along with computational methodology and results. In the extended model, flow velocity in the soil was driven by precipitation input along with transpiration and drainage. Water uptake by the roots determined the flow velocity in the root xylem, and this along with uptake of Pu in the transpiration stream drove advection and dispersion of the two Pu species in the xylem. During wet periods with high potential evapotranspiration, maximum flow velocities through the xylem would approached 600 cm/hr, orders of magnitude larger that flow velocities in the soil. Values for parameters and the correct conceptual viewpoint for Pu transport in plant xylem was uncertain. This motivated further experiments devoted

  18. Effects of transient receptor potential (TRP) channel agonists and antagonists on slowly adapting type II mechanoreceptors in the rat sinus hair follicle.

    PubMed

    Cahusac, Peter M B

    2009-12-01

    The possible functional role of transient receptor potential (TRP) channels was investigated by testing various TRP agonists and antagonists in an isolated rat sinus hair follicle preparation. Extracellular recordings from slowly adapting type II mechanoreceptor units were made. The antagonist capsazepine depressed spontaneous and mechanically evoked activity, with an IC(50) of 82 microM. In one-third of units, capsazepine caused a selective depression of mechanically evoked firing, such that the existing spontaneous firing was interrupted by an absence of activity during the mechanical stimulus. The broad spectrum TRP blocker ruthenium red (30 microM) had inconsistent effects, although in some units a delayed onset (following wash) bursting and paroxysmal firing ensued. The agonist icilin (50-100 microM) had an excitatory effect on spontaneous firing, and (-)-menthol (200 microM) had inconsistent effects. Cinnamaldehyde (1-2 mM) depressed all types of activity equally, mechanically evoked and spontaneous. Camphor (0.5-2 mM) also depressed all types of activity, although it had a preferential effect on spontaneous activity. Capsaicin (1-10 microM) and allyl isothiocyanate (50-100 microM) had no clear effects. These results rule out any role for TRPA1 and TRPV1 channels in mechanotransduction processes of slowly adapting type II mechanoreceptors.

  19. Influence of electric-double-layer structure on the transient response of nanochannels

    NASA Astrophysics Data System (ADS)

    Schiffbauer, Jarrod; Yossifon, Gilad

    2014-05-01

    A fundamental Poisson-Nernst-Planck-Stokes model is presented for the impedance response of a long nanochannel under zero bias, capturing the effects of surface conduction and the coupling between transverse momentum and axial ion distribution in a manner reminiscent of Taylor dispersion. This is shown to result in a shift of the impedance frequency spectrum with bulk concentration similar to previous experimental observation [Schiffbauer, Liel, and Yossifon, Phys. Rev. E 89, 033017 (2014), 10.1103/PhysRevE.89.033017]. It further predicts an additional downward shift in frequency with increasing viscosity. Finally, the introduction of a phenomenological model for the impedance response of a dynamic Stern layer in parallel with the diffuse layer transport model is shown to yield good agreement between theory and experiment. As a result, we are able to obtain an equivalent circuit model based on the fundamental model and proposed corrections.

  20. Transient and Prolonged Response of Chicken Cecum Mucosa to Colonization with Different Gut Microbiota

    PubMed Central

    Volf, Jiri; Polansky, Ondrej; Varmuzova, Karolina; Gerzova, Lenka; Sekelova, Zuzana; Faldynova, Marcela; Babak, Vladimir; Medvecky, Matej; Smith, Adrian L.; Kaspers, Bernd; Velge, Philippe; Rychlik, Ivan

    2016-01-01

    In this study we determined protein and gene expression in the caeca of newly hatched chickens inoculated with cecal contents sourced from hens of different ages. Over 250 proteins exhibited modified expression levels in response to microbiota inoculation. The most significant inductions were observed for ISG12-2, OASL, ES1, LYG2, DMBT1-L, CDD, ANGPTL6, B2M, CUZD1, IgM and Ig lambda chain. Of these, ISG12-2, ES1 and both immunoglobulins were expressed at lower levels in germ-free chickens compared to conventional chickens. In contrast, CELA2A, BRT-2, ALDH1A1, ADH1C, AKR1B1L, HEXB, ALDH2, ALDOB, CALB1 and TTR were expressed at lower levels following inoculation of microbiota. When chicks were given microbiota preparations from different age donors, the recipients mounted differential responses to the inoculation which also differed from the response profile in naturally colonised birds. For example, B2M, CUZD1 and CELA2A responded differently to the inoculation with microbiota of 4- or 40-week-old hens. The increased or decreased gene expression could be recorded 6 weeks after the inoculation of newly hatched chickens. To characterise the proteins that may directly interact with the microbiota we characterised chicken proteins that co-purified with the microbiota and identified a range of host proteins including CDD, ANGPTL6, DMBT1-L, MEP1A and Ig lambda. We propose that induction of ISG12-2 results in reduced apoptosis of host cells exposed to the colonizing commensal microbiota and that CDD, ANGPTL6, DMBT1-L, MEP1A and Ig lambda reduce contact of luminal microbiota with the gut epithelium thereby reducing the inflammatory response. PMID:27685470

  1. Atmospheric Response to Zonal Variations in Midlatitude SST: Transient and Stationary Eddies and Their Feedback(.

    NASA Astrophysics Data System (ADS)

    Inatsu, Masaru; Mukougawa, Hitoshi; Xie, Shang-Ping

    2003-10-01

    Midwinter storm track response to zonal variations in midlatitude sea surface temperatures (SSTs) has been investigated using an atmospheric general circulation model under aquaplanet and perpetual-January conditions. Zonal wavenumber-1 SST variations with a meridionally confined structure are placed at various latitudes. Having these SST variations centered at 30°N leads to a zonally localized storm track, while the storm track becomes nearly zonally uniform when the same SST forcing is moved farther north at 40° and 50°N. Large (small) baroclinic energy conversion north of the warm (cold) SST anomaly near the axis of the storm track (near 40°N) is responsible for the large (small) storm growth. The equatorward transfer of eddy kinetic energy by the ageostrophic motion and the mechanical damping are important to diminish the storm track activity in the zonal direction.Significant stationary eddies form in the upper troposphere, with a ridge (trough) northeast of the warm (cold) SST anomaly at 30°N. Heat and vorticity budget analyses indicate that zonally localized condensational heating in the storm track is the major cause for these stationary eddies, which in turn exert a positive feedback to maintain the localized storm track by strengthening the vertical shear near the surface. These results indicate an active role of synoptic eddies in inducing deep, tropospheric-scale response to midlatitude SST variations. Finally, the application of the model results to the real atmosphere is discussed.

  2. A free radical scavenger edaravone suppresses systemic inflammatory responses in a rat transient focal ischemia model.

    PubMed

    Fujiwara, Norio; Som, Angel T; Pham, Loc-Duyen D; Lee, Brian J; Mandeville, Emiri T; Lo, Eng H; Arai, Ken

    2016-10-28

    A free radical scavenger edaravone is clinically used in Japan for acute stroke, and several basic researches have carefully examined the mechanisms of edaravone's protective effects. However, its actions on pro-inflammatory responses under stroke are still understudied. In this study, we subjected adult male Sprague-Dawley rats to 90-min middle cerebral artery (MCA) occlusion followed by reperfusion. Edaravone was treated twice via tail vein; after MCA occlusion and after reperfusion. As expected, edaravone-treated group showed less infarct volume and edema formation compared with control group at 24-h after an ischemic onset. Furthermore, edaravone reduced the levels of plasma interleukin (IL)-1β and matrix metalloproteinase-9 at 3-h after ischemic onset. Several molecules besides IL-1β and MMP-9 are involved in inflammatory responses under stroke conditions. Therefore, we also examined whether edaravone treatment could decrease a wide range of pro-inflammatory cytokines/chemokines by testing rat plasma samples with a rat cytokine array. MCAO rats showed elevations in plasma levels of CINC-1, Fractalkine, IL-1α, IL-1ra, IL-6, IL-10, IP-10, MIG, MIP-1α, and MIP-3α, and all these increases were reduced by edaravone treatment. These data suggest that free radical scavengers may reduce systemic inflammatory responses under acute stroke conditions, and therefore, oxidative stress can be still a viable target for acute stroke therapy.

  3. Transient inhibition of primary motor cortex suppresses hand muscle responses during a reactive reach to grasp.

    PubMed

    Bolton, David A E; Patel, Rupesh; Staines, W Richard; McIlroy, William E

    2011-10-24

    Rapid balance reactions such as compensatory reach to grasp represent important response strategies following unexpected loss of balance. While it has been assumed that early corrective actions arise from subcortical networks, recent research has prompted speculation about the potential role of cortical involvement. With reach to grasp reactions there is evidence of parallels in the control of perturbation-evoked reaching versus rapid voluntary reaching. However, the potential role of cortical involvement in such rapid balance reactions remains speculative. To test if cortical motor regions are involved we used continuous theta burst stimulation (cTBS) to temporarily suppress the hand area of primary motor cortex (M1) in participants involved in two reaching conditions: (1) rapid compensatory perturbation-evoked reach to grasp and (2) voluntary reach to grasp in response to an auditory cue. We hypothesized that following cTBS to the left M1 hand area we would find diminished EMG responses in the reaching (right) hand for both compensatory and voluntary movements. To isolate balance reactions to the upper limb participants were seated in an elevated tilt-chair with a stable handle positioned in front of their right shoulder. The chair was held vertical by a magnet and triggered to fall backward randomly. To regain balance, participants were instructed to reach for the handle as quickly as possible with the right hand upon chair release. Intermixed with perturbation trials, participants were also required to reach for the same handle but in response to an auditory tone. Muscle activity was recorded from several muscles of the right arm/hand using electromyography. As expected, movement time and muscle onsets were much faster following perturbation versus auditory-cued reaching. The novel finding from our study was the reduced amplitude of hand muscle activity post-cTBS for both perturbation-cued and auditory-cued reaches. Moreover, this reduction was specific to the

  4. Structural response of transient heat loading on a molybdenum surface exposed to low-energy helium ion irradiation

    NASA Astrophysics Data System (ADS)

    Sinclair, G.; Tripathi, J. K.; Diwakar, P. K.; Hassanein, A.

    2016-03-01

    The advancement of fusion reactor engineering is currently inhibited by the lack of knowledge surrounding the stability of plasma facing components (PFCs) in a tokamak environment. During normal operation, events of high heat loading occur periodically where large amounts of energy are imparted onto the PFC surface. Concurrently, irradiation by low-energy helium ions present in the fusion plasma can result in the synthesis of a fibre form nanostructure on the PFC surface, called ‘fuzz’. In order to understand how this heterogeneous structure evolves and deforms in response to transient heat loading, a pulsed Nd:YAG millisecond laser is used to simulate these events on a fuzz form molybdenum (Mo) surface. Performance was analysed by three metrics: nanostructure evolution, particle emission, and improvement in optical properties. Experiments performed at the upper end of the expected range for type-I edge-localized modes (ELMs) found that the helium-induced nanostructure completely disappears after 200 pulses of the laser at 1.5 MJ m-2. In situ mass loss measurements found that the amount of particles leaving the surface increases as energy density increases and the rate of emission increases with pulse count. Finally, optical properties assisted in providing a qualitative indication of fuzz density on the Mo surface; after 400 pulses at 1.5 MJ m-2, the optical reflectivity of the damaged surface is ~90% of that of a mirror polished Mo sample. These findings provide different results than previous studies done with tungsten (W), and further help illustrate the complicated nature of how transient events of high heat loading in a tokamak environment might impact the performance and lifetime of PFCs in ITER and future DEMO devices (Ueda et al 2014 Fusion Eng. Des. 89 901-6).

  5. Conductometric study of shear-dependent processes in red cell suspensions. II. Transient cross-stream hematocrit distribution.

    PubMed

    Pribush, A; Meyerstein, D; Meiselman, H J; Meyerstein, N

    2004-01-01

    A novel experimental approach based on electrical properties of red blood cell (RBC) suspensions was applied to study the effects of the size and morphology of RBC aggregates on the transient cross-stream hematocrit distribution in suspensions flowing through a square cross-section flow channel. The information about the effective size of RBC aggregates and their morphology is extracted from the capacitance (C) and conductance (G) recorded during RBC aggregation, whereas a slower process of particle migration is manifested by delayed long-term changes in the conductance. Migration-induced changes in the conductance measured at low shear rates (< or =3.1 s(-1)) for suspensions of RBCs in a strongly aggregating medium reveal an increase to a maximum followed by a decrease to the stationary level. The ascending branch of G(t) curves reflects the aggregate migration in the direction of decreasing shear rate. A further RBC aggregation in the region of lower shear stresses leads to the formation of RBC networks and results in the transformation of the rheological behavior of suspensions from the thinning to the thickening. It is suggested that the descending branches of the G(t) curves recorded at low shear rates reflect an adjustment of the Hct distribution to a new state caused by a partial dispersion of RBC networks. For suspensions of non-aggregating RBCs it is found that depending on whether the shear rate is higher or lower compared with the prior value, individual RBCs migrate either toward the centerline of the flow or in the opposite direction.

  6. Mesospheric, Thermospheric, and Ionospheric Responses to Acoustic and Gravity Waves Generated by Transient Forcing

    NASA Astrophysics Data System (ADS)

    Snively, J. B.; Zettergren, M. D.

    2014-12-01

    Strong acoustic waves with periods ~1-4 minutes have been confirmed to perturb the ionosphere following their generation by earthquakes [e.g., Garcia et al., GRL, 40(5), 2013] and volcanic eruption events [e.g., Heki, GRL, 33, L14303, 2006]. Clear acoustic and gravity wave signatures have also been reported in ionospheric data above strong tropospheric convection [Nishioka, GRL, 40(21), 2013], and prior modeling results suggest that convectively-generated acoustic waves with ~3-4 minute periods are readily detectable above their sources in TEC [Zettergren and Snively, GRL, 40(20), 2013]. These observations have provided quantitative insight into the coupling of processes occurring near Earth's surface with the upper atmosphere and ionosphere over short time-scales. Here, we investigate acoustic waves and short-period gravity waves generated by sources near ground level, and the observable responses of the mesosphere, lower-thermosphere, and ionosphere (MLTI) systems. Numerical simulations are performed using a nonlinear, compressible, atmospheric dynamics model, in cylindrically-axisymmetric coordinates, to investigate wave generation, upward propagation, steepening, and dissipation. Acoustic waves may produce observable signatures in the mesospheric hydroxyl airglow layer [e.g., Snively, GRL, 40(17), 2013], and can strongly perturb the lower-thermosphere and E- and F-region ionosphere, prior to the arrival of simultaneously-generated gravity waves. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for mid and low latitudes using a 2D dipole magnetic field coordinate system [Zettergren and Snively, GRL, 40(20), 2013], we investigate its response to realistic acoustic wave perturbations. In particular, we demonstrate that the MLT and ionospheric responses are significantly and nonlinearly determined by the acoustic wave source geometry, spectrum, and amplitude, in addition to the local ambient state of the

  7. LES of wind farm response to transient scenarios using a high fidelity actuator disk model

    NASA Astrophysics Data System (ADS)

    Moens, M.; Duponcheel, M.; Winckelmans, G.; Chatelain, P.

    2016-09-01

    Large eddy simulations coupled to Actuator Disks are used to investigate wake effects in wind farms. An effort is made on the wind turbine model: it uses the prevailing velocities at each point of the disk to estimate the aerodynamic loads and is improved using a tip-loss correction and realistic control schemes. This accurate and efficient tool is used to study the wind farm response in terms of flow and power production during an unsteady scenario: this work focuses on an emergency shutdown of one rotor inside a wind farm.

  8. Analysis of the transient response of shell structures by numerical methods.

    NASA Technical Reports Server (NTRS)

    Geers, T. L.; Sobel, L. H.

    1972-01-01

    This paper examines some basic considerations underlying dynamic shell response analysis and the impact of these considerations upon the practical aspects of solution by numerical methods. Emphasis is placed on the solution of linear problems. The present states of development of the finite difference and finite element methods are reviewed, and techniques for the treatment of temporal variation are discussed. An examination is made of the frequency parameters characteristic of thin shell theory, applied excitations, and spatial mesh geometries, and the significance of these parameters with respect to computational convergence is illustrated.

  9. In-plane response and mode II fracture response of Z-pin woven laminates

    NASA Astrophysics Data System (ADS)

    Huang, Hseng-Ji

    Textile composites are proven to be an attractive choice over traditional pre-preg based composites because of reduced manufacturing costs and improved transverse mechanical properties. However, similar to traditional pre-preg composites, 2D laminates consisting of multiple layers of laminae still suffer from delamination under impact or transverse loads. Z-pin (carbon fiber of small diameter inserted in the thickness direction-z) composites are a means to provide higher through-thethickness stiffness and strength that 2D woven composites lack. In this thesis, The influences of Z-pin density and Z-pin diameter on the response of Z-pin under in-plane loads (compression) and transverse loads (mode II fracture) are examined. Both experiments and numerical simulations were performed to address the problems. Compression tests were conducted first and failure mechanism in each loading scenario was identified, through optical and mechanical measurements, during and after the tests. This was followed by the development of different numerical models of varying degree of sophistication, which include in-plane 2D models, (used to study fiber distortion and damage due to Z-pin insertion), multi-layer 2D models, (used to provide an inexpensive multi-layer model to study the effect of phase difference due to stacking consolidation), and multi-layer-multi-cell models (used to provide a full 3D multi-layer and multi-representative unit cell description). The second part of this thesis investigates the mode II fracture response under static and dynamic loading. Discrete Cohesive Zone Model (DCZM) was adopted to obtain the fracture toughness in conjunction with experimental data. In dynamic test, a crack advance gage (CAG) was designed to capture the exact time when the crack begins to propagate. By use of these CAGs, the corresponding crack propagation speed between different CAGs can be computed accordingly. These observations are supplemented through high speed optical images

  10. A Study on Response of a Contoured Composite Panel with Co-cured Stiffeners Under Transient Loading

    NASA Astrophysics Data System (ADS)

    Begum, Shahnaaz; Jain, Prakash Chand; Venkatesh, Siddu

    2016-07-01

    Composite materials are emerging to be the best applied materials for aerospace applications. With rapid improvement in computational facilities, it is now possible to design the best composite lay up for a particular kind of application. This paper presents the development of a Finite Element model of a contoured composite panel with co-cured stiffeners using Finite Element Simulation. Commercial package ANSYS 15.0 is used for this study. Such half contoured panels find wide application in Aerospace industry. The panel is hinged at one of the ends and dynamically loaded at the other end over a relatively small surface area by transverse load. The response of the panel is observed for variation in stresses, deflections and failure criteria. The panel is expected to rotate about the hinge point by 4° from the initial point. The transient response of the composite panel has been observed for expected load and two test load cases and results reported in this paper. Analysis has become useful input for the design of panel.

  11. Estrogen-Responsive Transient Expression Assay Using a Brain Aromatase-Based Reporter Gene in Zebrafish (Danio rerio)

    PubMed Central

    Kim, Dong-Jae; Seok, Seung-Hyeok; Baek, Min-Won; Lee, Hui-Young; Na, Yi-Rang; Park, Sung-Hoon; Lee, Hyun-Kyoung; Dutta, Noton Kumar; Kawakami, Koichi; Park, Jae-Hak

    2009-01-01

    Whereas endogenous estrogens play an important role in the development, maintenance, and function of female and male reproductive organs, xenoestrogens present in the environment disrupt normal endocrine function in humans and wildlife. Various in vivo and in vitro assays have been developed to screen these xenoestrogens. However, traditional in vivo assays are laborious and unsuitable for large-scale screening, and in vitro assays do not necessarily replicate in vivo functioning. To overcome these limitations, we developed a transient expression assay in zebrafish, into which a brain aromatase (cyp19a1b)-based estrogen-responsive reporter gene was introduced. In response to 17β-estradiol (10−6 M) and heptachlor (10−6 M), zebrafish embryos carrying the reporter construct expressed enhanced green fluorescent protein in the olfactory bulb, telencephalon, preoptic area, and mediobasal hypothalamus. This system will serve to model the in vivo conversion and breakdown of estrogenic compounds and thus provide a rapid preliminary screening method to estimate their estrogenicity. PMID:19887024

  12. Evidence from simultaneous intracellular- and surface-pH transients that carbonic anhydrase II enhances CO2 fluxes across Xenopus oocyte plasma membranes

    PubMed Central

    Occhipinti, Rossana; Boron, Walter F.

    2014-01-01

    The α-carbonic anhydrases (CAs) are zinc-containing enzymes that catalyze the interconversion of CO2 and HCO3−. Here, we focus on human CA II (CA II), a ubiquitous cytoplasmic enzyme. In the second paper in this series, we examine CA IV at the extracellular surface. After microinjecting recombinant CA II in a Tris solution (or just Tris) into oocytes, we expose oocytes to 1.5% CO2/10 mM HCO3−/pH 7.50 while using microelectrodes to monitor intracellular pH (pHi) and surface pH (pHS). CO2 influx causes the familiar sustained pHi fall as well as a transient pHS rise; CO2 efflux does the opposite. Both during CO2 addition and removal, CA II increases the magnitudes of the maximal rate of pHi change, (dpHi/dt)max, and the maximal change in pHS, ΔpHS. Preincubating oocytes with the inhibitor ethoxzolamide eliminates the effects of CA II. Compared with pHS, pHi begins to change only after a delay of ∼9 s and its relaxation has a larger (i.e., slower) time constant (τpHi > τpHS). Simultaneous measurements with two pHi electrodes, one superficial and one deep, suggest that impalement depth contributes to pHi delay and higher τpHi. Using higher CO2/HCO3− levels, i.e., 5%/33 mM HCO3− or 10%/66 mM HCO3−, increases (dpHi/dt)max and ΔpHS, though not in proportion to the increase in [CO2]. A reaction-diffusion mathematical model (described in the third paper in this series) accounts for the above general features and supports the conclusion that cytosolic CA—consuming entering CO2 or replenishing exiting CO2—increases CO2 fluxes across the cell membrane. PMID:24965587

  13. Transient and oscillating response of Ovonic devices for high-speed electronics

    NASA Astrophysics Data System (ADS)

    Piccinini, E.; Brunetti, R.; Bordone, P.; Rudan, M.; Jacoboni, C.

    2016-12-01

    The electric response of Ovonic devices to a time-dependent voltage is analysed by means of a charge-transport model previously proposed by the authors. The numerical implementation of the model shows that the features of the I(V) characteristics depend not only upon the external bias but also on more complex effects due to the interplay between intrinsic microscopic relaxation times and the inevitable parasitic elements of the system. Either stable or oscillating solutions are found, according to the position of the load line. The model also allows for speculation on the potential of Ovonic materials in the design of selector devices for two-terminal non-volatile memories.

  14. Mechanism of Generation of Therapy Related Leukemia in Response to Anti-Topoisomerase II Agents

    PubMed Central

    Cowell, Ian G.; Austin, Caroline A.

    2012-01-01

    Type II DNA topoisomerases have the ability to generate a transient DNA double-strand break through which a second duplex can be passed; an activity essential for DNA decatenation and unknotting. Topoisomerase poisons stabilize the normally transient topoisomerase-induced DSBs and are potent and widely used anticancer drugs. However, their use is associated with therapy-related secondary leukemia, often bearing 11q23 translocations involving the MLL gene. We will explain recent discoveries in the fields of topoisomerase biology and transcription that have consequences for our understanding of the etiology of leukemia, especially therapy-related secondary leukemia and describe how these findings may help minimize the occurrence of these neoplasias. PMID:22829791

  15. Transient stability and control of renewable generators based on Hamiltonian surface shaping and power flow control. Part II, analysis.

    SciTech Connect

    Robinett, Rush D., III; Wilson, David Gerald

    2010-11-01

    The swing equations for renewable generators connected to the grid are developed and a wind turbine is used as an example. The swing equations for the renewable generators are formulated as a natural Hamiltonian system with externally applied non-conservative forces. A two-step process referred to as Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) is used to analyze and design feedback controllers for the renewable generators system. This formulation extends previous results on the analytical verification of the Potential Energy Boundary Surface (PEBS) method to nonlinear control analysis and design and justifies the decomposition of the system into conservative and non-conservative systems to enable a two-step, serial analysis and design procedure. The first step is to analyze the system as a conservative natural Hamiltonian system with no externally applied non-conservative forces. The Hamiltonian surface of the swing equations is related to the Equal-Area Criterion and the PEBS method to formulate the nonlinear transient stability problem. This formulation demonstrates the effectiveness of proportional feedback control to expand the stability region. The second step is to analyze the system as natural Hamiltonian system with externally applied non-conservative forces. The time derivative of the Hamiltonian produces the work/rate (power flow) equation which is used to ensure balanced power flows from the renewable generators to the loads. The Second Law of Thermodynamics is applied to the power flow equations to determine the stability boundaries (limit cycles) of the renewable generators system and enable design of feedback controllers that meet stability requirements while maximizing the power generation and flow to the load. Necessary and sufficient conditions for stability of renewable generators systems are determined based on the concepts of Hamiltonian systems, power flow, exergy (the maximum work that can be extracted from an energy flow) rate

  16. Novel configuration of a myosin II transient intermediate analogue revealed by quick-freeze deep-etch replica electron microscopy.

    PubMed

    Kimori, Yoshitaka; Baba, Norio; Katayama, Eisaku

    2013-02-15

    In the present paper, we described our attempt to characterize the rough three-dimensional features of the structural analogue of the key intermediate of myosin's cross-bridge cycle. Using quick-freeze deep-etch replica electron microscopy, we observed that actin-attached myosin during in vitro sliding was bent superficially as postulated by the conventional hypothesis, but in the opposite direction of the putative pre-power-stroke configuration, as for ADP·Vi (inorganic vanadate)-bound myosin. We searched for the conformational species with a similar appearance and found that SH1-SH2 (thiols 1 and 2)-cross-linked myosin is a good candidate. To characterize such small asymmetric structures, we employed a new pattern-recognition procedure that accommodates the metal-replicated samples. In this method, the best-matched views of the target microscopic images were selected from a comprehensive set of images simulated from known atomic co-ordinates of relevant proteins. Together with effective morphological filtering, we could define the conformational species and the view angles of the catalytic domain and the lever arm cropped from averaged images of disulfide-cross-linked myosin. Whereas the catalytic domain of the new conformer closely resembled the pPDM (N,N'-p-phenylenedimaleimide)-treated, but SH2 Lys705-cross-linked, structure (PDB code 1L2O), a minor product of the same cross-linking reaction, the lever arm projected differently. Using separately determined view angles of the catalytic domain and the lever arm, we built a model of disulfide-cross-linked myosin. Further combination with the 'displacement-mapping' procedure enabled us to reconstruct the global three-dimensional envelope of the unusual structure whose lever arm orientation is compatible with our reports on the actin-sliding cross-bridge structure. Assuming this conformer as the structural analogue of the transient intermediate during actin sliding, the power stroke of the lever arm might

  17. Gender differences in response to acute and chronic angiotensin II infusion: a translational approach

    PubMed Central

    Toering, Tsjitske J; van der Graaf, Anne Marijn; Visser, Folkert W; Buikema, Hendrik; Navis, Gerjan; Faas, Marijke M; Lely, A Titia

    2015-01-01

    Women with renal disease progress at a slower rate to end stage renal disease than men. As angiotensin II has both hemodynamic and direct renal effects, we hypothesized that the female protection may result from gender differences in responses to angiotensin II. Therefore, we studied gender differences in response to angiotensin II, during acute (human) and chronic (rats) angiotensin II administration. In young healthy men (n = 18) and women (n = 18) we studied the responses of renal hemodynamics (125I-iothalamate and 131I-Hippuran) and blood pressure to graded angiotensin II infusion (0.3, 1.0, and 3.0 ng/kg/min for 1 h). Men had increased responses of diastolic blood pressure (P = 0.01), mean arterial pressure (P = 0.05), and a more pronounced decrease in effective renal plasma flow (P = 0.009) than women. We measured the changes in proteinuria and blood pressure in response to chronic administration (200 ng/kg/min for 3 weeks) of angiotensin II in rats. Male rats had an increased response of proteinuria compared with females (GEE analysis, P = 0.001). Male, but not female, angiotensin II-treated rats had increased numbers of renal interstitial macrophages compared to sham-treated rats (P < 0.001). In conclusion, gender differences are present in the response to acute and chronic infusion of angiotensin II. Difference in angiotensin II sensitivity could play a role in gender differences in progression of renal disease. PMID:26149279

  18. A dynamic-biased dual-loop-feedback CMOS LDO regulator with fast transient response

    NASA Astrophysics Data System (ADS)

    Han, Wang; Maomao, Sun

    2014-04-01

    This paper presents a low-dropout regulator (LDO) for portable applications with dual-loop feedback and a dynamic bias circuit. The dual-loop feedback structure is adopted to reduce the output voltage spike and the response time of the LDO. The dynamic bias circuit enhances the slew rate at the gate of the power transistor. In addition, an adaptive miller compensation technique is employed, from which a single pole system is realized and over a 59° phase margin is achieved under the full range of the load current. The proposed LDO has been implemented in a 0.6-μm CMOS process. From the experimental results, the regulator can operate with a minimum dropout voltage of 200 mV at a maximum 300 mA load and IQ of 113 μA. The line regulation and load regulation are improved to 0.1 mV/V and 3.4 μV/mA due to the sufficient loop gain provided by the dual feedback loops. Under a full range load current step, the voltage spikes and the recovery time of the proposed LDO is reduced to 97 mV and 0.142 μs respectively.

  19. Electron temperature response to ECRH on FTU tokamak in transient conditions.

    NASA Astrophysics Data System (ADS)

    Jacchia, A.; Bruschi, A.; Cirant, S.; Granucci, G.; Sozzi, C.; de Luca, F.; Amadeo, P.; Bracco, G.; Tudisco, O.

    2001-10-01

    Steady-state electron heat transport analysis of FTU high density plasmas under Electron Cyclotron Heating (ECRH) shows "stiff" electron temperature profiles [1,2,3]. Plasma response to off-axis EC heating, in fact, exibits a lower limit to electron temperature gradient length, Lc , below which electron thermal conductivity switches to higher values. Stiffness, however, is attenuated in the plasma core of saw-tooth free discharges with flat-hollow temperature profile and during current ramp-up [3,4,5], in which cases the temperature gradient length can be brought to very low values by means of on-axis ECH. Steady and current ramp-up discharges probed by steady and modulated ECH are analyzed in terms of stiffnes. Critical gradient length dependence on local features of computed current density profile is discussed. [1] Sozzi, C. et al., Paper EXP5/13, Plasma Phys. Contr. Fus. Res., Proc.18th IAEA Conf., Sorrento, 2000. [2] Jacchia, A. et al. Topical Conference on Radio Frequency Power in Plasmas, Oxnard, USA, (2001). [3] Cirant, S. et al. Topical Conference on Radio Frequency Power in Plasmas, Oxnard, USA, (2001). [4] Sozzi, C. et al., EPS, Madeira 2001. [5] Bracco, G. et al.,Plasma Phys. Contr. Fus. Res., Proc.18th IAEA Conf., Sorrento, 2000.

  20. Thermal Response of Tritiated Co-deposits from JET and TFTR to Transient Heat Pulses

    SciTech Connect

    C.H. Skinner; N. Bekrisl; J.P. Coad; C.A. Gentile; A. Hassanein; R. Reiswig; S. Willms

    2002-05-30

    High heat flux interactions with plasma-facing components have been studied at microscopic scales. The beam from a continuous wave neodymium laser was scanned at high speed over the surface of graphite and carbon fiber composite tiles that had been retrieved from TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) after D-T plasma operations. The tiles have a surface layer of amorphous hydrogenated carbon that was co-deposited during plasma operations, and laser scanning has released more than 80% of the co-deposited tritium. The temperature rise of the co-deposit was much higher than that of the manufactured material and showed an extended time history. The peak temperature varied dramatically (e.g., 1,436 C compared to >2,300 C), indicating strong variations in the thermal conductivity to the substrate. A digital microscope imaged the co-deposit before, during, and after the interaction with the laser and revealed 100-micron scale hot spots during the interaction. Heat pulse durations of order 100 ms resulted in brittle destruction and material loss from the surface, whilst a duration of =10 ms showed minimal changes to the co-deposit. These results show that reliable predictions for the response of deposition areas to off-normal events such as ELMs (edge-localized modes) and disruptions in next-step devices need to be based on experiments with tokamak generated co-deposits.

  1. Ligand-field symmetry effects in Fe(II) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    SciTech Connect

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Kim, Tae Kyu; Groot, Frank M. F. de; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-02-28

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  2. Investigating the zonal wind response to SST warming using transient ensemble AGCM experiments

    NASA Astrophysics Data System (ADS)

    Palipane, Erool; Lu, Jian; Staten, Paul; Chen, Gang; Schneider, Edwin K.

    2017-01-01

    The response of the atmospheric circulation to greenhouse gas-induced SST warming is investigated using large ensemble experiments with two AGCMs, with a focus on the robust feature of the poleward shift of the eddy driven jet. In these experiments, large ensembles of simulations are conducted by abruptly switching the SST forcing on from January 1st to focus on the wintertime circulation adjustment. A hybrid, finite amplitude wave activity budget analysis is performed to elucidate the nonlinear and irreversible aspects of the eddy-mean flow interaction during the adjustment of the zonal wind towards a poleward shifted state. The results confirm the results from earlier more idealized studies, particularly the importance of reduced dissipation of wave activity, in which the midlatitude decrease of effective diffusivity appears to be dominant. This reduction in dissipation increases the survival of midlatitude waves. These surviving waves, when reaching the upper propagation level in the upper troposphere, are subject to the influence of the increase of reflection phase speed at the poleward side of the mean jet, and thus more waves are reflected equatorward across the jet, giving rise to a poleward transport of momentum and thus an eddy momentum flux convergence for the poleward shift. The relative importance of wave breaking-induced PV mixing versus diabatic PV source in the evolution of the Lagrangian PV gradient is also investigated. The former plays the dominant role in the PV gradient formation during the initial phase of the jet shift, while the latter actually opposes the evolution of the Lagrangian PV gradient at times.

  3. Transient response of microbial communities in a water well field to application of an impressed current.

    PubMed

    Medihala, P G; Lawrence, J R; Swerhone, G D W; Korber, D R

    2013-02-01

    Deterioration of water wells due to clogging and corrosion over time is a common problem where solutions may be costly and ineffective. Pilot studies have suggested that impressed current or cathodic protection may be used to reduce microbially-induced declines in water well performance. Two water wells in an alluvial aquifer close to the North Saskatchewan River were selected to study the response of subsurface microbial communities to the application of an impressed current as an anti-fouling technology. The treated well was exposed to an impressed current while the untreated well was used as a reference site. Biofilms grown on in situ coupons under the influence of the impressed current were significantly (p < 0.05) thicker (mean thickness = 67.3 μm) when compared to the biofilms (mean thickness = 19.3 μm) grown outside the electric field. Quantitative PCR analyses showed significantly (p < 0.05) higher numbers of total bacteria, iron- and nitrate-reducers in the electrified zone. Molecular analysis revealed that the predominant bacteria present in biofilms grown under the influence of the impressed current belonged to Rhodobacter spp., Sediminibacterium spp. and Geobacter spp. In addition to favouring the growth of biofilms, direct microscopic and ICP-AES analyses revealed that the impressed current also caused the deposition of iron and manganese on, and in the vicinity of, the well screen. Together, these factors contributed to rapid clogging leading to reduced specific pumping capacities of the treated well. The study revealed that the impressed current system was not effective as an anti-fouling technology but actually promoted both microbial growth and physical clogging in this aquifer.

  4. Investigating the zonal wind response to SST warming using transient ensemble AGCM experiments

    SciTech Connect

    Palipane, Erool; Lu, Jian; Staten, Paul; Chen, Gang; Schneider, Edwin K.

    2016-04-13

    The response of the atmospheric circulation to greenhouse gas-induced SST warming is investigated using large ensemble experiments with two AGCMs, with a focus on the robust feature of the poleward shift of the eddy driven jet. In these experiments, large ensembles of simulations are conducted by abruptly switching the SST forcing on from January 1st to focus on the wintertime circulation adjustment. A hybrid, nite amplitude wave activity budget analysis is performed to elucidate the nonlinear and irreversible aspects of the eddy-mean ow interaction during the adjustment of the zonal wind towards a poleward shifted state. The results conrm the results from earlier more idealized studies, particularly the importance of reduced dissipation of wave activity and the dominant role of the decrease of elective diffusivity in the midlatitudes. Some quantitative discrences do exist between the wave activity budgets of our more realistic experiments and the earlier idealized ones, including larger wave activity tendency and diabatic wave source, and a somewhat greater role of the changing PV gradient in the total reduction of the wave activity dissipation. The relative importance of wave breaking-induced PV mixing versus diabatic PV source in the evolution of the Lagrangian PV gradient is also investigated. The former plays the dominant role in the PV gradient formation during the initial phase of the jet shift, while the latter even opposes the evolution of the Lagrangian PV gradient at times. The possible involvement of the wave reflection level at the poleward flank of the mean jet is also investigated.

  5. Fault Response to Variations of Loading Rate and/or Dynamic Stress Transients, from the Analysis of 1811 Repeating Micro-Earthquakes at Parkfield (CA)

    NASA Astrophysics Data System (ADS)

    Malagnini, L.; Nadeau, R. M.; Munafo, I.; Dreger, D. S.; Cocco, M.; Mayeda, K. M.

    2014-12-01

    Using an approach developed for quantifying ground-motion, we analyze the spectral characteristics of 1811 repeating micro-earthquakes from 163 clusters near Parkfield (CA). Corner frequencies of a selected subset of events are also computed (Brune spectral model). Our calculations provide unprecedented accuracy on the calculation of the seismic moments of each individual event. A strong transient (3-10+ years) affects the spectral amplitudes of most repeating micro-earthquakes after the Parkfield Mw 6.0 main shock of 2004, showing a significant increase of amplitudes at the onset of the SAF postseismic response. The largest relative moment variation ((ΔM0)max/M0regular) with respect to unperturbed events, the maximum creep velocity (VMax), and the postseismic relaxation time (τ), all systematically increase, along the creeping section of the SAF, toward the area that slipped coseismically during the 2004 Parkfield main earthquake. Postseismic perturbations of the repeats' seismic moments are up to an order of magnitude larger than the typical seismic moments of the undisturbed events; recurrence times also show a systematic behavior. Dynamic stress perturbations (increased loading rate of the specific asperities, and/or changes of normal stress across the SAF) are likely to be responsible for the observed variations of the repeats' seismic moments and recurrence times. In addition to the postseismic response to a large event on the (locked) adjacent portion of the SAF, anomalous responses may be induced by: i) giant events at teleseismic distances (i.e., Sumatra, 2004); ii) strong regional events, within ~100 km (i.e., Loma Prieta, 1989, and Landers, 1992); iii) small earthquakes (M~2) in close vicinity to specific clusters. After the 2004 Parkfield main shock, the (shallow) clusters of small-magnitude repeats showed the largest relative perturbations, and the largest absolute cumulative slips. We point out an apparent inconsistency between the self

  6. NASTRAN postprocessor program for transient response to input accelerations. [procedure for generating and writing modal input data on tapes using NASTRAN

    NASA Technical Reports Server (NTRS)

    Wingate, R. T.; Jones, T. C.; Stephens, M. V.

    1973-01-01

    The description of a transient analysis program for computing structural responses to input base accelerations is presented. A hybrid modal formulation is used and a procedure is demonstrated for generating and writing all modal input data on user tapes via NASTRAN. Use of several new Level 15 modules is illustrated along with a problem associated with reading the postprocessor program input from a user tape. An example application of the program is presented for the analysis of a spacecraft subjected to accelerations initiated by thrust transients. Experience with the program has indicated it to be very efficient and economical because of its simplicity and small central memory storage requirements.

  7. Responsabilidad = Responsibility. Level II. Student Book and Teacher's Edition.

    ERIC Educational Resources Information Center

    Center for Civic Education, Calabasas, CA.

    This curriculum presents an overview of responsibility as a concept intrinsic to the functioning of a democratic society. The curriculum has been developed to provide students with an increased awareness of the importance of responsibility in their own lives and its place in contemporary society, and to encourage their capacity and inclination to…

  8. Using prior information to separate the temperature response to greenhouse gas forcing from that of aerosols - Estimating the transient climate response

    NASA Astrophysics Data System (ADS)

    Schurer, Andrew; Hegerl, Gabriele

    2016-04-01

    The evaluation of the transient climate response (TCR) is of critical importance to policy makers as it can be used to calculate a simple estimate of the expected warming given predicted greenhouse gas emissions. Previous studies using optimal detection techniques have been able to estimate a TCR value from the historic record using simulations from some of the models which took part in the Coupled Model Intercomparison Project Phase 5 (CMIP5) but have found that others give unconstrained results. At least partly this is due to degeneracy between the greenhouse gas and aerosol signals which makes separation of the temperature response to these forcings problematic. Here we re-visit this important topic by using an adapted optimal detection analysis within a Bayesian framework. We account for observational uncertainty by the use of an ensemble of instrumental observations, and model uncertainty by combining the results from several different models. This framework allows the use of prior information which is found to help separate the response to the different forcings leading to a more constrained estimate of TCR.

  9. Simulation of steady state and transient cardiac muscle response experiments with a Huxley-based contraction model.

    PubMed

    Negroni, Jorge A; Lascano, Elena C

    2008-08-01

    A cardiac muscle model is presented with the purpose of representing a wide range of mechanical experiments at constant and transient Ca(2+) concentration. Modifications of a previous model were: weak and power attached crossbridge states, a troponin system involving three consecutive regulatory troponin-tropomyosin units acting together in Ca(2+) kinetics and detachment constants depending on crossbridge length. This model improved cooperativity (Hill coefficient close to 4) and the force-velocity relationship, and incorporated the representation of the four phases of muscle response to length and force steps, isotonic shortening and isosarcometric contractions, preserving previous satisfactory results. Moreover, experimentally reported effects, such as length dependence on Ca(2+) affinity, the decreased cooperativity at higher Ca(2+) concentrations, temperature effects on the stiffness-frequency relationship and the isometric internal shortening due to series elasticity, were obtained. In conclusion, the model is more comprehensive than a previous version because it is able to represent a wider variety of steady state experiments, the mechanical variables in twitches can be adequately related to intracellular Ca(2+), and all the simulations were performed with the same set of parameters.

  10. Resistive wall mode feedback control in EXTRAP T2R with improved steady-state error and transient response

    NASA Astrophysics Data System (ADS)

    Brunsell, P. R.; Olofsson, K. E. J.; Frassinetti, L.; Drake, J. R.

    2007-10-01

    Experiments in the EXTRAP T2R reversed field pinch [P. R. Brunsell, H. Bergsåker, M. Cecconello et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] on feedback control of m =1 resistive wall modes (RWMs) are compared with simulations using the cylindrical linear magnetohydrodynamic model, including the dynamics of the active coils and power amplifiers. Stabilization of the main RWMs (n=-11,-10,-9,-8,+5,+6) is shown using modest loop gains of the order G ˜1. However, other marginally unstable RWMs (n=-2,-1,+1,+2) driven by external field errors are only partially canceled at these gains. The experimental system stability limit is confirmed by simulations showing that the latency of the digital controller ˜50μs is degrading the system gain margin. The transient response is improved with a proportional-plus-derivative controller, and steady-state error is improved with a proportional-plus-integral controller. Suppression of all modes is obtained at high gain G ˜10 using a proportional-plus-integral-plus-derivative controller.

  11. The effect of Platelet Lysate on osteoblast proliferation associated with a transient increase of the inflammatory response in bone regeneration.

    PubMed

    Ruggiu, Alessandra; Ulivi, Valentina; Sanguineti, Francesca; Cancedda, Ranieri; Descalzi, Fiorella

    2013-12-01

    Platelet Lysate (PL) contains a cocktail of growth factors and cytokines, which actively participates in tissue repair and its clinical application has been broadly described. The aim of this study was to assess the regenerative potential of PL for bone repair. We demonstrated that PL stimulation induces a transient increase of the inflammatory response in quiescent human osteoblasts, via NF-kB activation, COX-2 induction, PGE2 production and secretion of pro-inflammatory cytokines. Furthermore, we showed that long-term PL stimulation enhances proliferation of actively replicating osteoblasts, without affecting their differentiation potential, along with changes of cell morphology, resulting in increased cell density at confluence. In confluent resting osteoblasts, PL treatment induced resumption of proliferation, change in cell morphology and increase of cell density at confluence. A burst of PL treatment (24-h) was sufficient to trigger such processes in both conditions. These results correlated with up-regulation of the proliferative and survival pathways ERKs and Akt and with cell cycle re-activation via induction of CyclinD1 and phosphorylation of Rb, following PL stimulation. Our findings demonstrate that PL treatment results in activation and expansion of resting osteoblasts, without affecting their differentiation potential. Therefore PL represents a good therapeutic candidate in regenerative medicine for bone repair.

  12. Transient early neurotrophin release and delayed inflammatory cytokine release by microglia in response to PAR-2 stimulation.

    PubMed

    Chen, Chen-Wen; Chen, Qian-Bo; Ouyang, Qing; Sun, Ji-Hu; Liu, Fang-Ting; Song, Dian-Wen; Yuan, Hong-Bin

    2012-06-25

    Activated microglia exerts both beneficial and deleterious effects on neurons, but the signaling mechanism controlling these distinct responses remain unclear. We demonstrated that treatment of microglial cultures with the PAR-2 agonist, 2-Furoyl-LIGRLO-NH2, evoked early transient release of BDNF, while sustained PAR-2 stimulation evoked the delayed release of inflammatory cytokines (IL-1 β and TNF-α) and nitric oxide. Culture medium harvested during the early phase (at 1 h) of microglial activation induced by 2-Furoyl-LIGRLO-NH2 (microglial conditioned medium, MCM) had no deleterious effects on cultured neurons, while MCM harvested during the late phase (at 72 h) promoted DNA fragmentation and apoptosis as indicated by TUNEL and annexin/PI staining. Blockade of PAR-1 during the early phase of PAR-2 stimulation enhanced BDNF release (by 11%, small but significant) while a PAR-1 agonist added during the late phase (24 h after 2-Furoyl-LIGRLO-NH2 addition) suppressed the release of cytokines and NO. The neuroprotective and neurotoxic effects of activated microglial exhibit distinct temporal profiles that are regulated by PAR-1 and PAR-2 stimulation. It may be possible to facilitate neuronal recovery and repair by appropriately timed stimulation and inhibition of microglial PAR-1 and PAR-2 receptors.

  13. Determination of charge transfer resistance and capacitance of microbial fuel cell through a transient response analysis of cell voltage.

    PubMed

    Ha, Phuc Thi; Moon, Hyunsoo; Kim, Byung Hong; Ng, How Yong; Chang, In Seop

    2010-03-15

    An alternative method for determining the charge transfer resistance and double-layer capacitance of microbial fuel cells (MFCs), easily implemented without a potentiostat, was developed. A dynamic model with two parameters, the charge transfer resistance and double-layer capacitance of electrodes, was derived from a linear differential equation to depict the current generation with respect to activation overvoltage. This model was then used to fit the transient cell voltage response to the current step change during the continuous operation of a flat-plate type MFC fed with acetate. Variations of the charge transfer resistance and the capacitance value with respect to the MFC design conditions (biocatalyst existence and electrode area) and operating parameters (acetate concentration and buffer strength in the catholyte) were then determined to elucidate the validity of the proposed method. This model was able to describe the dynamic behavior of the MFC during current change in the activation loss region; having an R(2) value of over 0.99 in most tests. Variations of the charge transfer resistance value (thousands of Omega) according to the change of the design factors and operational factors were well-correlated with the corresponding MFC performances. However, though the capacitance values (approximately 0.02 F) reflected the expected trend according to the electrode area change and catalyst property, they did not show significant variation with changes in either the acetate concentration or buffer strength.

  14. Transient response of the Hadley Centre coupled ocean-atmosphere model to increasing carbon dioxide. Part 3: Analysis of global-mean response using simple models

    SciTech Connect

    Murphy, J.M.

    1995-03-01

    The roles of surface, atmospheric, and oceanic feedbacks in controlling the global-mean transient response of a coupled ocean-atmosphere general circulation model (AOGCM) to increasing carbon dioxide are investigated. The analysis employs a four-box energy balance model (EBM) and an oceanic box-diffusion model (BDM) both tuned to the simulated general circulation model response. The land-sea contrast in the surface warming is explained almost entirely by the shortwave radiative feedbacks associated with changes in cloud and surface albedo. The oceanic thermal inertia delays the response; however, the initial delay is enhanced by increases in Anarctic sea-ice cover, which substantially reduce the effective climate sensitivity of the model in the first half of the 75-year experiment. When driven by the observed anthropogenic greenhouse forcing from the pre-industrial period to present day, the energy balance model overestimates the warming observed over land. However, inclusion of the direct forcing due to anthropogenic tropospheric sulphate aerosol eliminates the land/sea contrast in the response at 1990, leaving the simulated warming over land slightly below the observed value, although the rapid warming observed during the 1980s is well reproduced. The vertical penetration of the oceanic response is small below 1000 m. Within the top 1000 m the effective diffusivities are substantially enhanced by reduced convection and thermohaline overturning, driven by increased precipitation minus evaporation at high latitudes. These changes in ocean heat transport become significant after year 30, whereupon the effective oceanic heat capacity increases substantially, although this increase is partially offset by the effect of changes in the sea-ice margin.

  15. A transient elevated irisin blood concentration in response to prolonged, moderate aerobic exercise in young men and women.

    PubMed

    Kraemer, R R; Shockett, P; Webb, N D; Shah, U; Castracane, V D

    2014-02-01

    Irisin, a newly discovered, PGC-1α dependent myokine, has recently been shown to increase in circulation in response to sprint exercise. This study examined the effect of prolonged exercise on irisin concentrations in young men (n=7) as well as in young women (n=5) during different stages of the menstrual cycle. Seven young men completed 90 min of treadmill exercise at 60% of VO2max and a resting control trial. Five women completed the same exercise protocol in two different trials: during the early follicular phase and mid-luteal phase of the menstrual cycle. Blood samples were collected and analyzed for irisin concentrations immediately before exercise, at 54 and 90 min of exercise, and at 20 min of recovery (R20). Findings revealed that by 54 min of a 90 min treadmill exercise protocol at 60% of VO2max, irisin concentrations significantly increased 20.4% in young men and 20.3% as well as 24.6% in young women during the early follicular and mid-luteal phases of the menstrual cycle, respectively. However, by 90 min of exercise as well as R20, irisin concentrations were no longer elevated. Stage of the menstrual cycle did not affect responses in young women. Findings indicate that prolonged aerobic exercise produces a transient increase in irisin concentrations during the first hour of exercise for both genders and suggest that this form of moderate exercise may be helpful in improving fat metabolism.

  16. Drinking and arterial blood pressure responses to ANG II in young and old rats.

    PubMed

    Thunhorst, Robert L; Beltz, Terry G; Johnson, Alan Kim

    2010-11-01

    We investigated water drinking and arterial blood pressure responses to intravenous infusions of ANG II in young (4 mo), middle-aged adult (12 mo), and old (29 mo) male Brown Norway rats. Infusions of ANG II began with arterial blood pressure either at control levels or at reduced levels following injection of the vasodilator minoxidil. Under control conditions, mean arterial pressure (MAP) in response to ANG II rose to the same level for all groups, and middle-aged and old rats drank as much or more water in response to ANG II compared with young rats, depending on whether intakes were analyzed using absolute or body weight-adjusted values. When arterial blood pressure first was reduced with minoxidil, MAP in response to ANG II stabilized at significantly lower levels compared with control conditions for all groups. Young rats drank significantly more water under reduced pressure conditions compared with control conditions, while middle-aged and old rats did not. Urine volume in response to ANG II was lower, while water balance was higher, under conditions of reduced pressure compared with control conditions. Baroreflex control of heart rate was substantially reduced in old rats compared with young and middle-aged animals. In summary, young rats appear to be more sensitive to the inhibitory effects of increased arterial blood pressure on water drinking than are older animals.

  17. The vibration of a box-type structure. II - Response to a travelling pressure wave.

    NASA Technical Reports Server (NTRS)

    Popplewell, N.

    1971-01-01

    A finite element method is formulated for determining the transient response of a box-type structure to a traveling, arbitrarily shaped pressure wave. The method is illustrated by considering an example of practical concern - the sonic boom. The acceleration-time histories of a closed box are compared with those obtained experimentally from a simulated boom. Satisfactory agreement is obtained with only four rectangular elements per individual face and a simplified loading of the box.

  18. Response-restriction analysis: II. Alteration of activity preferences.

    PubMed Central

    Hanley, Gregory P; Iwata, Brian A; Roscoe, Eileen M; Thompson, Rachel H; Lindberg, Jana S

    2003-01-01

    We used response-restriction (RR) assessments to identify the preferences of 7 individuals with mental retardation for a variety of vocational and leisure activities. We subsequently increased their engagement in nonpreferred activities using several procedures: response restriction per se versus a Premack-type contingency (Study 1), supplemental reinforcement for engagement in target activities (Study 2), and noncontingent pairing of reinforcers with nonpreferred activities (Study 3). Results indicated that preferences are not immutable and can be altered through a variety of relatively benign interventions and that the results of RR assessments may be helpful in determining which types of procedures may be most effective on an individual basis. PMID:12723867

  19. Dissipative interface waves and the transient response of a three-dimensional sliding interface with Coulomb friction

    NASA Astrophysics Data System (ADS)

    Dunham, Eric M.

    2005-02-01

    We investigate the linearized response of two elastic half-spaces sliding past one another with constant Coulomb friction to small three-dimensional perturbations. Starting with the assumption that friction always opposes slip velocity, we derive a set of linearized boundary conditions relating perturbations of shear traction to slip velocity. Friction introduces an effective viscosity transverse to the direction of the original sliding, but offers no additional resistance to slip aligned with the original sliding direction. The amplitude of transverse slip depends on a nondimensional parameter η=csτ0/μv0, where τ0 is the initial shear stress, 2v0 is the initial slip velocity, μ is the shear modulus, and cs is the shear wave speed. As η→0, the transverse shear traction becomes negligible, and we find an azimuthally symmetric Rayleigh wave trapped along the interface. As η→∞, the inplane and antiplane wavesystems frictionally couple into an interface wave with a velocity that is directionally dependent, increasing from the Rayleigh speed in the direction of initial sliding up to the shear wave speed in the transverse direction. Except in these frictional limits and the specialization to two-dimensional inplane geometry, the interface waves are dissipative. In addition to forward and backward propagating interface waves, we find that for η>1, a third solution to the dispersion relation appears, corresponding to a damped standing wave mode. For large-amplitude perturbations, the interface becomes isotropically dissipative. The behavior resembles the frictionless response in the extremely strong perturbation limit, except that the waves are damped. We extend the linearized analysis by presenting analytical solutions for the transient response of the medium to both line and point sources on the interface. The resulting self-similar slip pulses consist of the interface waves and head waves, and help explain the transmission of forces across fracture

  20. Immersion infection of germ-free zebrafish with Listeria monocytogenes induces transient expression of innate immune response genes

    PubMed Central

    Shan, Ying; Fang, Chun; Cheng, Changyong; Wang, Yong; Peng, Jinrong; Fang, Weihuan

    2015-01-01

    Zebrafish, Denio rerio, can be an alternative to other classic animal models for human infectious diseases to examine the processes of microbial infections and host–pathogen interactions in vivo because of their small body dimension but large clutch size. We established germ-free zebrafish infection models of Listeria monocytogenes through different routes of infection: oral immersion and injection via yolk sac, brain ventricle and blood island. Immersion of zebrafish larva even with 1010 CFU/mL L. monocytogenes EGDe strain in egg water was unable to cause mortality, but GFP-expressing bacteria in the gut lumen can be observed in frozen sections. Several selected maker genes of the innate immune system, including cyp1a, irg1l, il1b, and mmp9, were significantly induced by oral immersion not only with strain EGDe, but also with strain M7 and L. innocua, though to a lesser degree (P < 0.01). Such induction appears to be transient with peak at 48 h post-infection, but returned to basal level at 72 h post-infection. Of the three injection routes, mortality after infection by yolk sac was 80% in early stage of infection. Few eggs can survive and hatch. Injection into zebrafish embryos via brain ventricle or blood island led to progressive lethal infection. L. mocytogenes EGDe showed steady replication in the fish embryos and was far more pathogenic than strain M7, which is consistent with findings in the murine model. We conclude that zebrafish can serve as susceptible and microscopically visible infection models for L. monocytogenes via different routes and can be applied to further studies on the interactions between bacterial virulence factors and host immune responses. PMID:25972853

  1. Recorded seismic response of Pacific Park Plaza. II. System identification

    USGS Publications Warehouse

    Safak, F.; Celebi, M.

    1992-01-01

    This is the second of two companion papers on the recorded seismic response of the Pacific Park Plaza building, in Emeryville, Calif., during the October 17, 1989, Ms = 7.1 (surface-wave magnitude) Loma Prieta earthquake. In this second part, the recorded data are analyzed in more detail by using system-identification techniques. The three-dimensional behavior and the coupled modes of the building are determined, and the effects of soil-structure interaction are investigated. The study shows that the response of the building is nonlinear at the beginning, and becomes linear after 17 sec into the earthquake. The dominant motion of the building follows an elliptical path oriented in the southeast-northwest direction. Some of the modes are complex, with nonproportional damping, and there are phase differences among modal response components. The fundamental mode of the building is a translation in the southeast-northwest direction at 0.4 Hz, with 13% damping. The wing displacements relative to the center core are large, about 50% of the center core displacements, and indicate significant torsion in the center core. The soil-structure interaction is characterized by a vibration at 0.7 Hz. This is believed to be the fundamental frequency of the surrounding soil medium. The rocking motions of the building are negligible.

  2. Modified sprint interval training protocols. Part II. Psychological responses.

    PubMed

    Townsend, Logan K; Islam, Hashim; Dunn, Emily; Eys, Mark; Robertson-Wilson, Jennifer; Hazell, Tom J

    2017-04-01

    Sprint-interval training (SIT) is a viable method to improve health and fitness. However, researchers have questioned the utility of SIT because of its strenuous nature. The current study aimed to determine if manipulating the sprint and recovery duration, while maintaining the 1:8 work to rest ratio, could uncover a more favourable SIT protocol. Nine healthy active males (age, 23.3 ± 3.0 years; body mass index, 22.4 ± 2.2 kg·m(-2); maximal oxygen consumption, 48.9 ± 5.3 mL·kg(-1)·min(-1)) participated in 3 experimental running SIT sessions: (i) 30:240 (4 × 30-s efforts, 240-s recovery), (ii) 15:120 (8 × 15-s efforts, 120-s recovery), (iii) 5:40 (24 × 5-s efforts, 40-s recovery), and (iv) a final behavioural choice follow-up session. Affect, intentions, task self-efficacy, enjoyment, and preference were evaluated. Midway through exercise, affect became more positive for 5:40 compared with 30:240 (p < 0.05) and postexercise affect was greater for both 5:40 (p = 0.014) and 15:120 (p = 0.015) compared with 30:240. Participants expressed greater intentions to perform 5:40 3 and 5 times/week compared with 15:120 and 30:240 (p < 0.05). Participants felt more confident in their ability to perform 5:40 (p = 0.001) and 15:120 (p = 0.008) compared with 30:240. The 5:40 session was also rated as more enjoyable than 15:120 (p = 0.025) and 30:240 (p = 0.026). All participants preferred the 5:40 protocol. These data suggest that shorter sprints with more repetitions are perceived as more enjoyable and lead to greater intentions to engage in SIT.

  3. Responsive Persistence Part II. Practices of Postmodern Therapists.

    PubMed

    Sutherland, Olga; Dienhart, Anna; Turner, Jean

    2013-10-01

    This article, a companion to Part I of this series of articles, discusses how therapists informed by social constructionist and postmodern ideas enact persistence in their work with families. Transcripts and video-recordings of therapy interaction facilitated by selected major champions for three postmodern (collaborative) therapies: Michael White (narrative therapy), Harlene Anderson (collaborative language systems approach), and Bill O'Hanlon (solution-oriented therapy) were examined for persistence practices. The article offers a range of possible ways in which postmodern therapists may enact their influence in facilitating generative and helpful conversations with families and remain responsive to clients' preferences and understandings. Implications for family therapy practice, training, and supervision are discussed.

  4. Luminous Extragalactic Transients

    NASA Astrophysics Data System (ADS)

    O'Brien, Paul; Jonker, Peter; Athena Explosive Transients Working Group

    2015-09-01

    The ESA Athena X-ray observatory mission will combine exceptionally high throughout with high spectral-energy resolution and will revolutionise many aspects of high-energy astrophysics. Many of the most powerful transient sources, including gamma-ray bursts and tidal disruptions events, are bright X-ray sources. Athena will be designed to have a fast-response capability permitting efficient observations of many transients. We will summarise the proposed capability of the mission and illustrate science programs to study transients ranging from the most distant GRBs to nuclear activity in nearby galaxies.

  5. Picroside II protects myocardium from ischemia/reperfusion-induced injury through inhibition of the inflammatory response

    PubMed Central

    Li, Jian-Zhe; Xie, Mei-Qing; Mo, Dan; Zhao, Xiao-Fang; Yu, Shu-Yi; Liu, Li-Juan; Wu, Cheng; Yang, Yang

    2016-01-01

    The inflammatory response is important in the pathogenesis of myocardial ischemia/reperfusion (I/R) injury. Picroside II, the primary active constituent of Picrorhizae, has been reported to protect the myocardium from I/R-induced injury, however, the exact mechanism underlying these protective effects remains unclear. The aim of the present study was to investigate the mechanism underlying the protective effects of picroside II on I/R-induced myocardial injury. Adult male Sprague-Dawley rats underwent 1 h left coronary artery occlusion followed by 3 h reperfusion. Picroside II was administered (10 mg/kg) via the tail vein 30 min prior to left coronary artery occlusion. The results revealed that pretreatment of picroside II could significantly alleviate I/R-induced myocardial injury concomitantly with a decrease in inflammatory factor production. In addition, picroside II was also able to decrease high mobility group box 1 (HMGB1) expression, and release and downregulate the expression of the receptor for advanced glycation end products (RAGE), toll-like receptor (TLR)-2 and TLR-4. Furthermore, picroside II was able to inhibit nuclear factor-κB (NF-κB) activation. The results indicated that the protective effect of picroside II on I/R-induced myocardial injury was associated, at least partly, with inhibition of the inflammatory response by suppressing the HMGB1-RAGE/TLR-2/TLR-4-NF-κB signaling pathway. PMID:28105084

  6. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations (identification of lifting rotor system parameters from transient response data), Phase 7-B

    NASA Technical Reports Server (NTRS)

    Hohenemser, K. H.; Prelewicz, D. A.

    1973-01-01

    System identification methods have been applied to rotorcraft to estimate stability derivatives from transient flight control response data. While these applications assumed a linear constant coefficient representation of the rotorcraft, the computer experiments used transient responses in flap-bending and torsion of a rotor blade at high advance ratio which is a rapidly time varying periodic system. It was found that a simple system identification method applying a linear sequential estimator also called least square estimator or equation of motion estimator, is suitable for this periodic system and can be used directly if only the acceleration data are noise polluted. In the case of noise being present also in the state variable data the direct application of the estimator gave poor results.

  7. Postjunctional regulation by angiotensin II of alpha 1-adrenoceptor-mediated pressor responses in the rat.

    PubMed

    Marano, G; Argiolas, L

    1994-08-11

    The effects of angiotensin II on the vasopressor responses to the selective alpha 1-adrenoceptor agonist, phenylephrine, in intact and sympathectomized rats were investigated. Infusion of angiotensin II at subpressor doses significantly enhanced the pressor effects of phenylephrine in intact rats. We also found that in the chemically sympathectomized rat, where prejunctional sympathetic function is impaired, the effects of angiotensin II infusion on the pressor effects of phenylephrine were similar to those obtained in intact rats. Furthermore, pretreatment with valsartan ((S)-N-valeryl-N-([2'-(1H-tetrazol-5-yl)biphenyl-4-yl]-methyl)-val ine), a new selective angiotensin AT1 receptor antagonist, antagonized the effects of angiotensin II on phenylephrine-mediated pressor responses, whereas the administration of the selective angiotensin AT2 receptor antagonist, PD 123319 (1-[[4-(dimethylamino)-3-methylphenyl]-methyl]-5-(diphenylacetyl)- 4,5,6,7-tetrahydro-1H-imidazo[4,5-c]-pyridine-6-carboxylic acid, ditriflouroacetate, monohydrate), injected in bolus doses of 100 micrograms/kg, did not antagonize the enhancing effect of angiotensin II. Collectively, these data suggest that angiotensin II modulates the response to phenylephrine primarily at a postjunctional level through the activation of angiotensin AT1 receptors and that the suggested prejunctional facilitation mediated by angiotensin receptors is quantitatively much less important in the intact animal.

  8. Seismic response of transamerica building. II. System identification

    USGS Publications Warehouse

    Safak, E.; Celebi, M.

    1991-01-01

    A detailed analysis of the recorded seismic response of the Transamerica Building during the October 17, 1989 Loma Prieta earthquake is presented. The system identification algorithm used for the analysis is based on the discrete-time linear filtering approach with least-squares approximation, and assumes a multi-input, single-output model for the building. Fifteen modes in the north-south direction, and 18 modes in the east-west direction are identified from the records. The analysis shows that the building's response to the earthquake was dominated by a coupled mode of vibration at 0.28 Hz in the southwest-northeast direction, which is almost parallel to one of the diagonals in the building's square cross section. The reason for this behavior is the symmetry of the building's structural characteristics, as well as the strong polarization of the S-waves of the earthquake. Several higher modes of the building were excited during the strong-motion part of the earthquake. The results also show a significant amount of rocking in the building at a frequency of 2.15 Hz.

  9. Epidermal Growth Factor Receptor Transactivation by the Cannabinoid Receptor (CB1) and Transient Receptor Potential Vanilloid 1 (TRPV1) Induces Differential Responses in Corneal Epithelial Cells

    DTIC Science & Technology

    2010-01-01

    inhibitors of proteolytic release of heparin bound EGF ( HB -EGF). CB1- induced Ca2þ transients were reduced during exposure to either the CB1 antagonist...blockage eliminated this response. Furthermore, EGFR transactivation was abolished by inhibitors of proteolytic release of heparin bound EGF ( HB -EGF...IL-8 or IL-6 Chemiluminescent Immunoassay ; R&D Systems, Minneapolis, MN). The cells were washed with basic medium and then exposed to CPZ, or AM251

  10. Modeling and analysis of thermal-hydraulic response of uranium- aluminum reactor fuel plates under transient heatup conditions

    SciTech Connect

    Navarro-Valenti, S.; Kim, S.H.; Georgevich, V.; Taleyarkhan, R.P.; Fuketa, T.; Soyama, Kk.; Ishijima, K.; Kodaira, T.

    1995-12-31

    A 3-D model to predict the thermal behavior of ANS (Advanced Neutron Source) fuel miniplates has been developed. Possibility of explosive boiling was considered, and it was concluded that the heating rates (existant in NSRR tests) are not large enough for this to occur. However, transient boiling effects were pronounced. Because of the complexity of transient pool boiling and the unavailability of experimental data for the situations studied, an approximation was made that predicted the data very well within the uncertainties present. If pool boiling from the miniplates had been assumed to be steady during the heating pulse, the experimental data would have been greatly overestimated. This shows the importance of considering the transient nature of heat transfer in analysis of reactivity excursion accidents. An additional contribution of this work is that it provided data on highly subcooled steady nucleate boiling from the cooling portion of the thermocouple traces.

  11. Myosin-II sets the optimal response time scale of chemotactic amoeba

    NASA Astrophysics Data System (ADS)

    Hsu, Hsin-Fang; Westendorf, Christian; Tarantola, Marco; Bodenschatz, Eberhard; Beta, Carsten

    2014-03-01

    The response dynamics of the actin cytoskeleton to external chemical stimuli plays a fundamental role in numerous cellular functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin-II. Here we investigate the role of myosin-II in the response of the actin system to external stimuli. We used a microfluidic device in combination with a photoactivatable chemoattractant to apply stimuli to individual cells with high temporal resolution. We directly compare the actin dynamics in Dictyostelium discodelium wild type (WT) cells to a knockout mutant that is deficient in myosin-II (MNL). Similar to the WT a small population of MNL cells showed self-sustained oscillations even in absence of external stimuli. The actin response of MNL cells to a short pulse of chemoattractant resembles WT during the first 15 sec but is significantly delayed afterward. The amplitude of the dominant peak in the power spectrum from the response time series of MNL cells to periodic stimuli with varying period showed a clear resonance peak at a forcing period of 36 sec, which is significantly delayed as compared to the resonance at 20 sec found for the WT. This shift indicates an important role of myosin-II in setting the response time scale of motile amoeba. Institute of Physics und Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany.

  12. Rat Pial Microvascular Responses to Transient Bilateral Common Carotid Artery Occlusion and Reperfusion: Quercetin’s Mechanism of Action

    PubMed Central

    Lapi, D.; Vagnani, S.; Pignataro, G.; Esposito, E.; Paterni, M.; Colantuoni, A.

    2012-01-01

    The aim of the present study was to assess quercetin’s mechanism of action in rat pial microvessels during transient bilateral common carotid artery occlusion (BCCAO) and reperfusion. Rat pial microcirculation was visualized using fluorescence microscopy through a closed cranial window. Pial arterioles were classified in five orders of branchings. In ischemic rats, 30 min BCCAO and 60 min reperfusion caused arteriolar diameter decrease, microvascular leakage, leukocyte adhesion in venules, and reduction of capillary perfusion. Quercetin highest dose determined dilation in all arteriolar orders, by 40 ± 4% of baseline in order 2 vessels, and prevented microvascular permeability [0.15 ± 0.02 normalized gray levels (NGL)], leukocyte adhesion, and capillary failure. Protein kinase C (PKC) inhibition exerted by chelerythrine prior to quercetin attenuated quercetin-induced effects: order 2 arterioles dilated by 19.0 ± 2.4% baseline, while there was an increase in permeability (0.40 ± 0.05 NGL) and leukocyte adhesion with a marked decrease in capillary perfusion. Tyrosine kinase (TK) inhibition by tyrphostin 47 prior to quercetin lessened smaller pial arterioles responses, dilating by 20.7 ± 2.5% of baseline, while leakage increased (0.39 ± 0.04 NGL) sustained by slight leukocyte adhesion and ameliorated capillary perfusion. Inhibition of endothelium nitric oxide synthase (eNOS) by NG-nitro-L-arginine-methyl ester (L-NAME) prior to PKC or TK reduced the quercetin’s effects on pial arteriolar diameter and leakage. eNOS inhibition by L-NAME reduced quercetin effects on pial arteriolar diameter and leakage. Finally, combined inhibition of PKC and TK prior to quercetin abolished quercetin-induced effects, decreasing eNOS expression, while blocking ATP-sensitive potassium (KATP) channels by glibenclamide suppressed arteriolar dilation. In conclusion, the protective effects of quercetin could be due to different mechanisms resulting in NO

  13. Coupled Aerosol-Chemistry-Climate Twentieth-Century Transient Model Investigation: Trends in Short-Lived Species and Climate Responses

    NASA Technical Reports Server (NTRS)

    Koch, Dorothy; Bauer, Susanne E.; Del Genio, Anthony; Faluvegi, Greg; McConnell, Joseph R.; Menon, Surabi; Miller, Ronald L.; Rind, David; Ruedy, Reto; Schmidt, Gavin A.; Shindell, Drew

    2011-01-01

    The authors simulate transient twentieth-century climate in the Goddard Institute for Space Studies (GISS) GCM, with aerosol and ozone chemistry fully coupled to one another and to climate including a full dynamic ocean. Aerosols include sulfate, black carbon (BC), organic carbon, nitrate, sea salt, and dust. Direct and BC snow-albedo radiative effects are included. Model BC and sulfur trends agree fairly well with records from Greenland and European ice cores and with sulfur deposition in North America; however, the model underestimates the sulfur decline at the end of the century in Greenland. Global BC effects peak early in the century (1940s); afterward the BC effects decrease at high latitudes of the Northern Hemisphere but continue to increase at lower latitudes. The largest increase in aerosol optical depth occurs in the middle of the century (1940s-80s) when sulfate forcing peaks and causes global dimming. After this, aerosols decrease in eastern North America and northern Eurasia leading to regional positive forcing changes and brightening. These surface forcing changes have the correct trend but are too weak. Over the century, the net aerosol direct effect is -0.41 Watts per square meter, the BC-albedo effect is -0.02 Watts per square meter, and the net ozone forcing is +0.24 Watts per square meter. The model polar stratospheric ozone depletion develops, beginning in the 1970s. Concurrently, the sea salt load and negative radiative flux increase over the oceans around Antarctica. Net warming over the century is modeled fairly well; however, the model fails to capture the dynamics of the observedmidcentury cooling followed by the late century warming.Over the century, 20% of Arctic warming and snow ice cover loss is attributed to the BC albedo effect. However, the decrease in this effect at the end of the century contributes to Arctic cooling. To test the climate responses to sulfate and BC pollution, two experiments were branched from 1970 that removed

  14. Transient expression of βC1 protein differentially regulates host genes related to stress response, chloroplast and mitochondrial functions

    PubMed Central

    2010-01-01

    Background Geminiviruses are emerging plant pathogens that infect a wide variety of crops including cotton, cassava, vegetables, ornamental plants and cereals. The geminivirus disease complex consists of monopartite begomoviruses that require betasatellites for the expression of disease symptoms. These complexes are widespread throughout the Old World and cause economically important diseases on several crops. A single protein encoded by betasatellites, termed βC1, is a suppressor of gene silencing, inducer of disease symptoms and is possibly involved in virus movement. Studies of the interaction of βC1 with hosts can provide useful insight into virus-host interactions and aid in the development of novel control strategies. We have used the differential display technique to isolate host genes which are differentially regulated upon transient expression of the βC1 protein of chili leaf curl betasatellite (ChLCB) in Nicotiana tabacum. Results Through differential display analysis, eight genes were isolated from Nicotiana tabacum, at two and four days after infitration with βC1 of ChLCB, expressed under the control of the Cauliflower mosaic virus 35S promoter. Cloning and sequence analysis of differentially amplified products suggested that these genes were involved in ATP synthesis, and acted as electron carriers for respiration and photosynthesis processes. These differentially expressed genes (DEGs) play an important role in plant growth and development, cell protection, defence processes, replication mechanisms and detoxification responses. Kegg orthology based annotation system analysis of these DEGs demonstrated that one of the genes, coding for polynucleotide nucleotidyl transferase, is involved in purine and pyrimidine metabolic pathways and is an RNA binding protein which is involved in RNA degradation. Conclusion βC1 differentially regulated genes are mostly involved in chloroplast and mitochondrial functions. βC1 also increases the expression of those

  15. LOX-1 dependent overexpression of immunoglobulins in cardiomyocytes in response to angiotensin II.

    PubMed

    Kang, Bum-Yong; Hu, Changping; Prayaga, Sastry; Khaidakov, Magomed; Sawamura, Tatsuya; Seung, Ki-Bae; Mehta, Jawahar L

    2009-02-06

    LOX-1, a cell surface lectin-like receptor, is upregulated by oxidized low-density lipoprotein (ox-LDL) and angiotensin II (Ang II), and plays an important role in host defense. The specific C-type lectin domain on LOX-1 is essential for ox-LDL binding and internalization, generation of oxidant species and eliciting immune response. Here, we show that LOX-1 deletion alters genes that relate to immune response. Microarray (and qPCR) analysis of cardiac tissues showed downregulated expression of several immunoglobulins (Igk-V8, Igk-C, Igh-6, Igj, Ighg, Igh, and Igl-V1) in the LOX-1 knockout (KO) mice [p<0.05 vs. the wild-type (WT) mice]. The expression of these immunoglobulins was upregulated several-fold in the LOX-1 KO mice hearts when these mice were infused with Ang II (p<0.05, vs. WT mice). Importantly, cultured mouse HL-1 cardiomyocytes expressed these immunoglobulins, and pretreatment of cardiomyocytes with a specific anti-LOX-1 antibody enhanced the generation of immunoglobulins upon subsequent exposure to Ang II. These observations mirrored the data obtained from WT and LOX-1 KO mice hearts in the resting state and following Ang II infusion. This study provides first set of data on immunoglobulin expression in cardiac tissues of WT and LOX-1 KO mice and in cultured HL-1 cardiomyocytes, and demonstrates that LOX-1 inactivation leads to upregulation of immunoglobulins in cardiomyocytes upon challenge with Ang II.

  16. Potential Biosignatures in Super-Earth Atmospheres II. Photochemical Responses

    PubMed Central

    Gebauer, S.; Godolt, M.; Palczynski, K.; Rauer, H.; Stock, J.; von Paris, P.; Lehmann, R.; Selsis, F.

    2013-01-01

    Abstract Spectral characterization of super-Earth atmospheres for planets orbiting in the habitable zone of M dwarf stars is a key focus in exoplanet science. A central challenge is to understand and predict the expected spectral signals of atmospheric biosignatures (species associated with life). Our work applies a global-mean radiative-convective-photochemical column model assuming a planet with an Earth-like biomass and planetary development. We investigated planets with gravities of 1g and 3g and a surface pressure of 1 bar around central stars with spectral classes from M0 to M7. The spectral signals of the calculated planetary scenarios have been presented by in an earlier work by Rauer and colleagues. The main motivation of the present work is to perform a deeper analysis of the chemical processes in the planetary atmospheres. We apply a diagnostic tool, the Pathway Analysis Program, to shed light on the photochemical pathways that form and destroy biosignature species. Ozone is a potential biosignature for complex life. An important result of our analysis is a shift in the ozone photochemistry from mainly Chapman production (which dominates in Earth's stratosphere) to smog-dominated ozone production for planets in the habitable zone of cooler (M5–M7)-class dwarf stars. This result is associated with a lower energy flux in the UVB wavelength range from the central star, hence slower planetary atmospheric photolysis of molecular oxygen, which slows the Chapman ozone production. This is important for future atmospheric characterization missions because it provides an indication of different chemical environments that can lead to very different responses of ozone, for example, cosmic rays. Nitrous oxide, a biosignature for simple bacterial life, is favored for low stratospheric UV conditions, that is, on planets orbiting cooler stars. Transport of this species from its surface source to the stratosphere where it is destroyed can also be a key process

  17. Potential biosignatures in super-Earth atmospheres II. Photochemical responses.

    PubMed

    Grenfell, J L; Gebauer, S; Godolt, M; Palczynski, K; Rauer, H; Stock, J; von Paris, P; Lehmann, R; Selsis, F

    2013-05-01

    Spectral characterization of super-Earth atmospheres for planets orbiting in the habitable zone of M dwarf stars is a key focus in exoplanet science. A central challenge is to understand and predict the expected spectral signals of atmospheric biosignatures (species associated with life). Our work applies a global-mean radiative-convective-photochemical column model assuming a planet with an Earth-like biomass and planetary development. We investigated planets with gravities of 1g and 3g and a surface pressure of 1 bar around central stars with spectral classes from M0 to M7. The spectral signals of the calculated planetary scenarios have been presented by in an earlier work by Rauer and colleagues. The main motivation of the present work is to perform a deeper analysis of the chemical processes in the planetary atmospheres. We apply a diagnostic tool, the Pathway Analysis Program, to shed light on the photochemical pathways that form and destroy biosignature species. Ozone is a potential biosignature for complex life. An important result of our analysis is a shift in the ozone photochemistry from mainly Chapman production (which dominates in Earth's stratosphere) to smog-dominated ozone production for planets in the habitable zone of cooler (M5-M7)-class dwarf stars. This result is associated with a lower energy flux in the UVB wavelength range from the central star, hence slower planetary atmospheric photolysis of molecular oxygen, which slows the Chapman ozone production. This is important for future atmospheric characterization missions because it provides an indication of different chemical environments that can lead to very different responses of ozone, for example, cosmic rays. Nitrous oxide, a biosignature for simple bacterial life, is favored for low stratospheric UV conditions, that is, on planets orbiting cooler stars. Transport of this species from its surface source to the stratosphere where it is destroyed can also be a key process. Comparing 1g with

  18. HLA class II genes modulate vaccine-induced antibody responses to affect HIV-1 acquisition.

    PubMed

    Prentice, Heather A; Tomaras, Georgia D; Geraghty, Daniel E; Apps, Richard; Fong, Youyi; Ehrenberg, Philip K; Rolland, Morgane; Kijak, Gustavo H; Krebs, Shelly J; Nelson, Wyatt; DeCamp, Allan; Shen, Xiaoying; Yates, Nicole L; Zolla-Pazner, Susan; Nitayaphan, Sorachai; Rerks-Ngarm, Supachai; Kaewkungwal, Jaranit; Pitisuttithum, Punnee; Ferrari, Guido; McElrath, M Juliana; Montefiori, David C; Bailer, Robert T; Koup, Richard A; O'Connell, Robert J; Robb, Merlin L; Michael, Nelson L; Gilbert, Peter B; Kim, Jerome H; Thomas, Rasmi

    2015-07-15

    In the RV144 vaccine trial, two antibody responses were found to correlate with HIV-1 acquisition. Because human leukocyte antigen (HLA) class II-restricted CD4(+) T cells are involved in antibody production, we tested whether HLA class II genotypes affected HIV-1-specific antibody levels and HIV-1 acquisition in 760 individuals. Indeed, antibody responses correlated with acquisition only in the presence of single host HLA alleles. Envelope (Env)-specific immunoglobulin A (IgA) antibodies were associated with increased risk of acquisition specifically in individuals with DQB1*06. IgG antibody responses to Env amino acid positions 120 to 204 were higher and were associated with decreased risk of acquisition and increased vaccine efficacy only in the presence of DPB1*13. Screening IgG responses to overlapping peptides spanning Env 120-204 and viral sequence analysis of infected individuals defined differences in vaccine response that were associated with the presence of DPB1*13 and could be responsible for the protection observed. Overall, the underlying genetic findings indicate that HLA class II modulated the quantity, quality, and efficacy of antibody responses in the RV144 trial.

  19. Modeling the World Health Organization Disability Assessment Schedule II using non-parametric item response models.

    PubMed

    Galindo-Garre, Francisca; Hidalgo, María Dolores; Guilera, Georgina; Pino, Oscar; Rojo, J Emilio; Gómez-Benito, Juana

    2015-03-01

    The World Health Organization Disability Assessment Schedule II (WHO-DAS II) is a multidimensional instrument developed for measuring disability. It comprises six domains (getting around, self-care, getting along with others, life activities and participation in society). The main purpose of this paper is the evaluation of the psychometric properties for each domain of the WHO-DAS II with parametric and non-parametric Item Response Theory (IRT) models. A secondary objective is to assess whether the WHO-DAS II items within each domain form a hierarchy of invariantly ordered severity indicators of disability. A sample of 352 patients with a schizophrenia spectrum disorder is used in this study. The 36 items WHO-DAS II was administered during the consultation. Partial Credit and Mokken scale models are used to study the psychometric properties of the questionnaire. The psychometric properties of the WHO-DAS II scale are satisfactory for all the domains. However, we identify a few items that do not discriminate satisfactorily between different levels of disability and cannot be invariantly ordered in the scale. In conclusion the WHO-DAS II can be used to assess overall disability in patients with schizophrenia, but some domains are too general to assess functionality in these patients because they contain items that are not applicable to this pathology.

  20. Rac1 protein signaling is required for DNA damage response stimulated by topoisomerase II poisons.

    PubMed

    Huelsenbeck, Stefanie C; Schorr, Anne; Roos, Wynand P; Huelsenbeck, Johannes; Henninger, Christian; Kaina, Bernd; Fritz, Gerhard

    2012-11-09

    To investigate the potency of the topoisomerase II (topo II) poisons doxorubicin and etoposide to stimulate the DNA damage response (DDR), S139 phosphorylation of histone H2AX (γH2AX) was analyzed using rat cardiomyoblast cells (H9c2). Etoposide caused a dose-dependent increase in the γH2AX level as shown by Western blotting. By contrast, the doxorubicin response was bell-shaped with high doses failing to increase H2AX phosphorylation. Identical results were obtained by immunohistochemical analysis of γH2AX focus formation, comet assay-based DNA strand break analysis, and measuring the formation of the topo II-DNA cleavable complex. At low dose, doxorubicin activated ataxia telangiectasia mutated (ATM) but not ATM and Rad3-related (ATR). Both the lipid-lowering drug lovastatin and the Rac1-specific inhibitor NSC23766 attenuated doxorubicin- and etoposide-stimulated H2AX phosphorylation, induction of DNA strand breaks, and topo II-DNA complex formation. Lovastatin and NSC23766 acted in an additive manner. They did not attenuate doxorubicin-induced increase in p-ATM and p-Chk2 levels. DDR stimulated by topo II poisons was partially blocked by inhibition of type I p21-associated kinases. DDR evoked by the topoisomerase I poison topotecan remained unaffected by lovastatin. The data show that the mechanisms involved in DDR stimulated by topo II poisons are agent-specific with anthracyclines lacking DDR-stimulating activity at high doses. Pharmacological inhibition of Rac1 signaling counteracts doxorubicin- and etoposide-stimulated DDR by disabling the formation of the topo II-DNA cleavable complex. Based on the data we suggest that Rac1-regulated mechanisms are required for DNA damage induction and subsequent activation of the DDR following treatment with topo II but not topo I poisons.

  1. Bimodal concentration-response of nicotine involves the nicotinic acetylcholine receptor, transient receptor potential vanilloid type 1, and transient receptor potential ankyrin 1 channels in mouse trachea and sensory neurons.

    PubMed

    Kichko, Tatjana I; Lennerz, Jochen; Eberhardt, Mirjam; Babes, Ramona M; Neuhuber, Winfried; Kobal, Gerd; Reeh, Peter W

    2013-11-01

    High concentrations of nicotine, as in the saliva of oral tobacco consumers or in smoking cessation aids, have been shown to sensitize/activate recombinant transient receptor potential vanilloid type 1 (rTRPV1) and mouse TRPA1 (mTRPA1) channels. By measuring stimulated calcitonin gene-related peptide (CGRP) release from the isolated mouse trachea, we established a bimodal concentration-response relationship with a threshold below 10 µM (-)-nicotine, a maximum at 100 µM, an apparent nadir between 0.5 and 10 mM, and a renewed increase at 20 mM. The first peak was unchanged in TRPV1/A1 double-null mutants as compared with wild-types and was abolished by specific nicotinic acetylcholine receptor (nAChR) inhibitors and by camphor, discovered to act as nicotinic antagonist. The nicotine response at 20 mM was strongly pHe-dependent, - five times greater at pH 9.0 than 7.4, indicating that intracellular permeation of the (uncharged) alkaloid was required to reach the TRPV1/A1 binding sites. The response was strongly reduced in both null mutants, and more so in double-null mutants. Upon measuring calcium transients in nodose/jugular and dorsal root ganglion neurons in response to 100 µM nicotine, 48% of the vagal (but only 14% of the somatic) sensory neurons were activated, the latter very weakly. However, nicotine 20 mM at pH 9.0 repeatedly activated almost every single cultured neuron, partly by releasing intracellular calcium and independent of TRPV1/A1 and nAChRs. In conclusion, in mouse tracheal sensory nerves nAChRs are 200-fold more sensitive to nicotine than TRPV1/A1; they are widely coexpressed with the capsaicin receptor among vagal sensory neurons and twice as abundant as TRPA1. Nicotine is the major stimulant in tobacco, and its sensory impact through nAChRs should not be disregarded.

  2. Can intradermal administration of angiotensin II influence human heat loss responses during whole body heat stress?

    PubMed

    Fujii, Naoto; Meade, Robert D; Paull, Gabrielle; McGinn, Ryan; Foudil-bey, Imane; Akbari, Pegah; Kenny, Glen P

    2015-05-01

    It is unclear if angiotensin II, which can increase the production of reactive oxygen species (oxidative stress), modulates heat loss responses of cutaneous blood flow and sweating. We tested the hypothesis that angiotensin II-induced increases in oxidative stress impair cutaneous perfusion and sweating during rest and exercise in the heat. Eleven young (24 ± 4 yr) healthy adults performed two 30-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C). The first and second exercises were followed by a 20- and 40-min recovery. Four microdialysis fibers were placed in the forearm skin for continuous administration of either: 1) lactated Ringer (control), 2) 10 μM angiotensin II, 3) 10 mM ascorbate (an antioxidant), or 4) a combination of 10 μM angiotensin II + 10 mM ascorbate. Cutaneous vascular conductance (CVC; laser-Doppler perfusion units/mean arterial pressure) and sweating (ventilated capsule) were evaluated at each skin site. Compared with control, angiotensin II reduced both CVC and sweating at baseline resting and during each recovery in the heat (all P < 0.05). However, during both exercise bouts, there were no differences in CVC or sweating between the treatment sites (all P > 0.05). When ascorbate was coinfused with angiotensin II, the effect of angiotensin II on sweating was abolished (all P > 0.05); however, its effect on CVC at baseline resting and during each recovery remained intact (all P < 0.05). We show angiotensin II impairs cutaneous perfusion independent of oxidative stress, while it impairs sweating through increasing oxidative stress during exposure to an ambient heat stress before and following exercise.

  3. Can intradermal administration of angiotensin II influence human heat loss responses during whole body heat stress?

    PubMed Central

    Fujii, Naoto; Meade, Robert D.; Paull, Gabrielle; McGinn, Ryan; Foudil-bey, Imane; Akbari, Pegah

    2015-01-01

    It is unclear if angiotensin II, which can increase the production of reactive oxygen species (oxidative stress), modulates heat loss responses of cutaneous blood flow and sweating. We tested the hypothesis that angiotensin II-induced increases in oxidative stress impair cutaneous perfusion and sweating during rest and exercise in the heat. Eleven young (24 ± 4 yr) healthy adults performed two 30-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C). The first and second exercises were followed by a 20- and 40-min recovery. Four microdialysis fibers were placed in the forearm skin for continuous administration of either: 1) lactated Ringer (control), 2) 10 μM angiotensin II, 3) 10 mM ascorbate (an antioxidant), or 4) a combination of 10 μM angiotensin II + 10 mM ascorbate. Cutaneous vascular conductance (CVC; laser-Doppler perfusion units/mean arterial pressure) and sweating (ventilated capsule) were evaluated at each skin site. Compared with control, angiotensin II reduced both CVC and sweating at baseline resting and during each recovery in the heat (all P < 0.05). However, during both exercise bouts, there were no differences in CVC or sweating between the treatment sites (all P > 0.05). When ascorbate was coinfused with angiotensin II, the effect of angiotensin II on sweating was abolished (all P > 0.05); however, its effect on CVC at baseline resting and during each recovery remained intact (all P < 0.05). We show angiotensin II impairs cutaneous perfusion independent of oxidative stress, while it impairs sweating through increasing oxidative stress during exposure to an ambient heat stress before and following exercise. PMID:25767030

  4. American Physicists, Nuclear Weapons in World War II, and Social Responsibility

    NASA Astrophysics Data System (ADS)

    Badash, Lawrence

    2005-06-01

    Social responsibility in science has a centuries-long history, but it was such a minor thread that most scientists were unaware of the concept. Even toward the conclusion of the Manhattan Project, which produced the first nuclear weapons, only a handful of its participants had some reservations about use of a weapon of mass destruction. But the explosions over Hiroshima and Nagasaki not only made society more aware of the importance of science, they made scientists more aware of their responsibility to society. I describe the development of the concept of social responsibility and its appearance among American scientists both before and after the end of World War II.

  5. Role of multilayer-like interference effects on the transient optical response of Si3N4 films pumped with free-electron laser pulses

    NASA Astrophysics Data System (ADS)

    Casolari, F.; Bencivenga, F.; Capotondi, F.; Giangrisostomi, E.; Manfredda, M.; Mincigrucci, R.; Pedersoli, E.; Principi, E.; Masciovecchio, C.; Kiskinova, M.

    2014-05-01

    X-ray/optical cross-correlation methods are attracting increasing interest for exploring transient states of matter using ultrashort free-electron laser (FEL) pulses. Our paper shows that in such studies the difference in the penetration depth of the FEL-pump and the infrared (IR) probe pulses become important, in particular, when exploring the changes in the optical properties of solid targets. We discuss the role of interference effects, using a phenomenological model with excited and unperturbed slabs. The reliability of this model was experimentally verified by measuring the transient optical response of free-standing and silicon (Si) supported silicon nitride (Si3N4) films, simultaneously in reflection and transmission, using s- and p-polarized IR light. The changes in the Si3N4 optical refractive index, induced by the FEL pulses, have fully been described in the frame of the proposed model. The experimental results confirm that the differences, observed in the FEL-induced transient reflectance and transmittance of the Si3N4 targets with different thicknesses, arise from multilayer-like interferometric phenomena.

  6. SYK regulates macrophage MHC-II expression via activation of autophagy in response to oxidized LDL

    PubMed Central

    Choi, Soo-Ho; Gonen, Ayelet; Diehl, Cody J; Kim, Jungsu; Almazan, Felicidad; Witztum, Joseph L; Miller, Yury I

    2015-01-01

    Adaptive immunity, which plays an important role in the development of atherosclerosis, is mediated by major histocompatibility complex (MHC)-dependent antigen presentation. In atherosclerotic lesions, macrophages constitute an important class of antigen-presenting cells that activate adaptive immune responses to oxidized low-density lipoprotein (OxLDL). It has been reported that autophagy regulates adaptive immune responses by enhancing antigen presentation to MHC class II (MHC-II). In a previous study, we have demonstrated that SYK (spleen tyrosine kinase) regulates generation of reactive oxygen species (ROS) and activation of MAPK8/JNK1 in macrophages. Because ROS and MAPK8 are known to regulate autophagy, in this study we investigated the role of SYK in autophagy, MHC-II expression and adaptive immune response to OxLDL. We demonstrate that OxLDL induces autophagosome formation, MHC-II expression, and phosphorylation of SYK in macrophages. Gene knockout and pharmacological inhibitors of NOX2 and MAPK8 reduced OxLDL-induced autophagy. Using bone marrow-derived macrophages isolated from wild-type and myeloid-specific SYK knockout mice, we demonstrate that SYK regulates OxLDL-induced ROS generation, MAPK8 activation, BECN1-BCL2 dissociation, autophagosome formation and presentation of OxLDL-derived antigens to CD4+ T cells. ldlr−/− syk−/− mice fed a high-fat diet produced lower levels of IgG to malondialdehyde (MDA)-LDL, malondialdehyde-acetaldehyde (MAA)-LDL, and OxLDL compared to ldlr−/− mice. These results provide new insights into the mechanisms by which SYK regulates MHC-II expression via autophagy in macrophages and may contribute to regulation of adaptive immune responses in atherosclerosis. PMID:25946330

  7. HLA class II genes modulate vaccine-induced antibody responses to affect HIV-1 acquisition

    PubMed Central

    Prentice, Heather A.; Tomaras, Georgia D.; Geraghty, Daniel E.; Apps, Richard; Fong, Youyi; Ehrenberg, Philip K.; Rolland, Morgane; Kijak, Gustavo H.; Krebs, Shelly J.; Nelson, Wyatt; DeCamp, Allan; Shen, Xiaoying; Yates, Nicole L.; Zolla-Pazner, Susan; Nitayaphan, Sorachai; Rerks-Ngarm, Supachai; Kaewkungwal, Jaranit; Pitisuttithum, Punnee; Ferrari, Guido; Juliana McElrath, M.; Montefiori, David C.; Bailer, Robert T.; Koup, Richard A.; O’Connell, Robert J.; Robb, Merlin L.; Michael, Nelson L.; Gilbert, Peter B.; Kim, Jerome H.; Thomas, Rasmi

    2016-01-01

    In the RV144 vaccine trial, two antibody responses were found to correlate with HIV-1 acquisition. Because human leukocyte antigen (HLA) class II–restricted CD4+ T cells are involved in antibody production, we tested whether HLA class II genotypes affected HIV-1–specific antibody levels and HIV-1 acquisition in 760 individuals. Indeed, antibody responses correlated with acquisition only in the presence of single host HLA alleles. Envelope (Env)–specific immunoglobulin A (IgA) antibodies were associated with increased risk of acquisition specifically in individuals with DQB1*06. IgG antibody responses to Env amino acid positions 120 to 204 were higher and were associated with decreased risk of acquisition and increased vaccine efficacy only in the presence of DPB1*13. Screening IgG responses to overlapping peptides spanning Env 120–204 and viral sequence analysis of infected individuals defined differences in vaccine response that were associated with the presence of DPB1*13 and could be responsible for the protection observed. Overall, the underlying genetic findings indicate that HLA class II modulated the quantity, quality, and efficacy of antibody responses in the RV144 trial. PMID:26180102

  8. Coincident steam generator tube rupture and stuck-open safety relief valve carryover tests: MB-2 steam generator transient response test program

    SciTech Connect

    Garbett, K; Mendler, O J; Gardner, G C; Garnsey, R; Young, M Y

    1987-03-01

    In PWR steam generator tube rupture (SGTR) faults, a direct pathway for the release of radioactive fission products can exist if there is a coincident stuck-open safety relief valve (SORV) or if the safety relief valve is cycled. In addition to the release of fission products from the bulk steam generator water by moisture carryover, there exists the possibility that some primary coolant may be released without having first mixed with the bulk water - a process called primary coolant bypassing. The MB-2 Phase II test program was designed specifically to identify the processes for droplet carryover during SGTR faults and to provide data of sufficient accuracy for use in developing physical models and computer codes to describe activity release. The test program consisted of sixteen separate tests designed to cover a range of steady-state and transient fault conditions. These included a full SGTR/SORV transient simulation, two SGTR overfill tests, ten steady-state SGTR tests at water levels ranging from very low levels in the bundle up to those when the dryer was flooded, and three moisture carryover tests without SGTR. In these tests the influence of break location and the effect of bypassing the dryer were also studied. In a final test the behavior with respect to aerosol particles in a dry steam generator, appropriate to a severe accident fault, was investigated.

  9. Transient induction of photolyase activity in arrested frog cells in response to a short-wave ultraviolet segment of simulated ''sunlight''

    SciTech Connect

    Chao, C.C.; Lin-Chao, S.

    1987-05-29

    Induction of photolyase activity was studied in cultured frog cells using clonogenic assays. Exposure of arrested cells to a pre-irradiation (90% survival) of 254 nm ultraviolet light resulted in a transient enhancement of photolyase activity. Cells expressed a decreased level of photolyase activity in response to an equitoxic fluence of simulated sunlight wavelengths 280-310 nm. However, no significant increase of enzyme activity was detected in cells following treatment with sunlight wavelengths 310-330 nm. In addition, this process depends on newly biosynthesized protein(s).

  10. Analysis of Experimental Sea-level Transient Data and Analog Method of Obtaining Altitude Response for Turbine-propeller Engine with Relay-type Speed Control

    NASA Technical Reports Server (NTRS)

    Vasu, George; Pack, George J

    1951-01-01

    Correlation has been established between transient engine and control data obtained experimentally and data obtained by simulating the engine and control with an analog computer. This correlation was established at sea-level conditions for a turbine-propeller engine with a relay-type speed control. The behavior of the controlled engine at altitudes of 20,000 and 35,000 feet was determined with an analog computer using the altitude pressure and temperature generalization factors to calculate the new engine constants for these altitudes. Because the engine response varies considerably at altitude some type of compensation appears desirable and four methods of compensation are discussed.

  11. Catalina/Palomar Optical Transient

    NASA Astrophysics Data System (ADS)

    Ganeshalingam, M.; Griffith, C. V.; Filippenko, A. V.; Foley, R. J.

    2008-07-01

    Inspection of a CCD spectrum (range 330-1000 nm), obtained on July 7 UT with the 3-m Shane reflector (+ Kast spectrograph) at Lick Observatory, shows that the transient reported in ATel 1604 has a very blue, featureless continuum. This could be a very young Type II supernova (though at this time no clear hydrogen Balmer features are present), or some kind of Galactic transient. Further observations are encouraged.

  12. Optimizing adsorption of Pb(II) by modified litchi pericarp using the response surface methodology.

    PubMed

    Sun, Shujuan; Yang, Jili; Li, Yan; Wang, Kai; Li, Xiaochen

    2014-10-01

    Litchi pericarp was chemically modified as a novel bioadsorbent (MLP) for Pb(II) adsorption in this study. Operating parameters such as contact time, adsorbent dosage, and initial pH of solution were investigated using batch assays and further optimized using response surface methodology (RSM). The results showed that the MLP exhibited a high adsorption efficiency of 99.97% for Pb(II), which was optimal at a contact time of 71.56min, a initial pH of 6.81, and an adsorbent dose of 3.80g/L. Adsorption processes of Pb(II) by MLP could be well described with Langmuir or Freundlich isotherms and a pseudo-second-order kinetic model. The maximum adsorption capacity of Pb(II) by MLP was determined as 163.93mg/g, suggesting a highly promising potential for MLP to be used as a new bioadsorbent. Additionally, the thermodynamic study indicated that the adsorption process of Pb(II) by MLP was spontaneously and exothermic.

  13. Decadal-Scale Responses in Middle and Upper Stratospheric Ozone From SAGE II Version 7 Data

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.

    2014-01-01

    Stratospheric Aerosol and Gas Experiment (SAGE II) version 7 (v7) ozone profiles are analyzed for their decadal-scale responses in the middle and upper stratosphere for 1991 and 1992-2005 and compared with those from its previous version 6.2 (v6.2). Multiple linear regression (MLR) analysis is applied to time series of its ozone number density vs. altitude data for a range of latitudes and altitudes. The MLR models that are fit to the time series data include a periodic 11 yr term, and it is in-phase with that of the 11 yr, solar UV (Ultraviolet)-flux throughout most of the latitude/ altitude domain of the middle and upper stratosphere. Several regions that have a response that is not quite in-phase are interpreted as being affected by decadal-scale, dynamical forcings. The maximum minus minimum, solar cycle (SClike) responses for the ozone at the low latitudes are similar from the two SAGE II data versions and vary from about 5 to 2.5% from 35 to 50 km, although they are resolved better with v7. SAGE II v7 ozone is also analyzed for 1984-1998, in order to mitigate effects of end-point anomalies that bias its ozone in 1991 and the analyzed results for 1991-2005 or following the Pinatubo eruption. Its SC-like ozone response in the upper stratosphere is of the order of 4%for 1984-1998 vs. 2.5 to 3%for 1991-2005. The SAGE II v7 results are also recompared with the responses in ozone from the Halogen Occultation Experiment (HALOE) that are in terms of mixing ratio vs. pressure for 1991-2005 and then for late 1992- 2005 to avoid any effects following Pinatubo. Shapes of their respective response profiles agree very well for 1992-2005. The associated linear trends of the ozone are not as negative in 1992-2005 as in 1984-1998, in accord with a leveling off of the effects of reactive chlorine on ozone. It is concluded that the SAGE II v7 ozone yields SC-like ozone responses and trends that are of better quality than those from v6.2.

  14. Electrodynamic response of the type-II Weyl semimetal YbMnBi2

    DOE PAGES

    Chinotti, M.; Pal, A.; Ren, W. J.; ...

    2016-12-01

    Weyl fermions play a major role in quantum field theory but have been quite elusive as fundamental particles. These quasi-two-dimensional bismuth layers based materials were recently designed and provide an arena for studying the interplay between anisotropic Dirac fermions, magnetism, and structural changes, allowing the formation of Weyl fermions in condensed matter. We perform an optical investigation of YbMnBi 2 , a representative type-II Weyl semimetal, and contrast its excitation spectrum with the optical response of the more conventional semimetal EuMnBi 2 . This comparative study allows us to disentangle the optical fingerprints of type-II Weyl fermions, but also challengesmore » the present theoretical understanding of their electrodynamic response.« less

  15. Electrodynamic response of the type-II Weyl semimetal YbMnBi2

    NASA Astrophysics Data System (ADS)

    Chinotti, M.; Pal, A.; Ren, W. J.; Petrovic, C.; Degiorgi, L.

    2016-12-01

    Weyl fermions play a major role in quantum field theory but have been quite elusive as fundamental particles. Materials based on quasi-two-dimensional bismuth layers were recently designed and provide an arena for studying the interplay between anisotropic Dirac fermions, magnetism, and structural changes, allowing the formation of Weyl fermions in condensed matter. Here, we perform an optical investigation of YbMnBi2, a representative type-II Weyl semimetal, and contrast its excitation spectrum with the optical response of the more conventional semimetal EuMnBi2. Our comparative study allows us to disentangle the optical fingerprints of type-II Weyl fermions, but also challenges the present theoretical understanding of their electrodynamic response.

  16. AS04, an aluminum salt- and TLR4 agonist-based adjuvant system, induces a transient localized innate immune response leading to enhanced adaptive immunity.

    PubMed

    Didierlaurent, Arnaud M; Morel, Sandra; Lockman, Laurence; Giannini, Sandra L; Bisteau, Michel; Carlsen, Harald; Kielland, Anders; Vosters, Olivier; Vanderheyde, Nathalie; Schiavetti, Francesca; Larocque, Daniel; Van Mechelen, Marcelle; Garçon, Nathalie

    2009-11-15

    Adjuvant System 04 (AS04) combines the TLR4 agonist MPL (3-O-desacyl-4'-monophosphoryl lipid A) and aluminum salt. It is a new generation TLR-based adjuvant licensed for use in human vaccines. One of these vaccines, the human papillomavirus (HPV) vaccine Cervarix, is used in this study to elucidate the mechanism of action of AS04 in human cells and in mice. The adjuvant activity of AS04 was found to be strictly dependent on AS04 and the HPV Ags being injected at the same i.m. site within 24 h of each other. During this period, AS04 transiently induced local NF-kappaB activity and cytokine production. This led to an increased number of activated Ag-loaded dendritic cells and monocytes in the lymph node draining the injection site, which further increased the activation of Ag-specific T cells. AS04 was also found to directly stimulate those APCs in vitro but not directly stimulate CD4(+) T or B lymphocytes. These AS04-induced innate responses were primarily due to MPL. Aluminum salt appeared not to synergize with or inhibit MPL, but rather it prolonged the cytokine responses to MPL at the injection site. Altogether these results support a model in which the addition of MPL to aluminum salt enhances the vaccine response by rapidly triggering a local cytokine response leading to an optimal activation of APCs. The transient and confined nature of these responses provides further supporting evidence for the favorable safety profile of AS04 adjuvanted vaccines.

  17. Forcing function effects on unsteady aerodynamic gust response. II - Low solidity airfoil row response

    NASA Technical Reports Server (NTRS)

    Henderson, Gregory H.; Fleeter, Sanford

    1992-01-01

    The paper investigates the fundamental gust modeling assumption on the basis of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady period flow field is generated by rotating flows of perforated plates and airfoil cascades, with the resulting unsteady periodic chordwise pressure response of a downstream low solidity stator row determined by miniature pressure transducers embedded within selected airfoils. When the forcing function exhibited the characteristics of a linear-theory gust, the resulting response on the downstream stator airfoils was in excellent agreement with the linear-theory models. When the forcing function did not exhibit linear-theory gust characteristics, the resulting unsteady aerodynamic response of the downstream stators was much more complex and correlated poorly with the linear-theory gust predictions. It is shown that the forcing function generator significantly affects the resulting gust response, with the complexity of the response characteristics increasing from the perforated-plate to the airfoil-cascade forcing functions.

  18. Species specificity and augmentation of responses to class II major histocompatibility complex molecules in human CD4 transgenic mice

    PubMed Central

    1992-01-01

    Murine T cell responses to human class II major histocompatibility complex (MHC) molecules were shown to be a minimum of 20-70-fold lower than responses to allogeneic molecules. Transgenic mice expressing slightly below normal (75-95%) or very high (250-380%) cell surface levels of human CD4 were utilized to determine whether this was due to a species-specific interaction between murine CD4 and class II molecules. Human CD4 was shown to function in signal transduction events in murine T cells based on the ability of anti-human CD4 antibody to synergize with suboptimal doses of anti-murine CD3 antibody in stimulating T cell proliferation. In mice expressing lower levels of human CD4, T cell responses to human class II molecules were enhanced up to threefold, whereas allogeneic responses were unaltered. In mice expressing high levels of human CD4, responses to human class II molecules were enhanced at least 10-fold, whereas allogeneic responses were between one and three times the level of normal responses. The relatively greater enhancement of the response to human class II molecules in both lines argues for a preferential interaction between human CD4 and human class II molecules. In mice expressing lower levels of human CD4, responses to human class II molecules were blocked by antibodies to CD4 of either species, indicating participation by both molecules. In mice expressing high levels of human CD4, responses to both human and murine class II molecules were almost completely blocked with anti-human CD4 antibody, whereas anti-murine CD4 antibody had no effect. However, anti-murine CD4 continued to synergize with anti-CD3 in stimulating T cell proliferation in these mice. Thus, overexpression of human CD4 selectively impaired the ability of murine CD4 to assist in the process of antigen recognition. The ability of human CD4 to support a strong allogeneic response under these conditions indicates that this molecule can interact with murine class II molecules to a

  19. Involvement of Escherichia coli DNA polymerase II in response to oxidative damage and adaptive mutation.

    PubMed

    Escarceller, M; Hicks, J; Gudmundsson, G; Trump, G; Touati, D; Lovett, S; Foster, P L; McEntee, K; Goodman, M F

    1994-10-01

    DNA polymerase II (Pol II) is regulated as part of the SOS response to DNA damage in Escherichia coli. We examined the participation of Pol II in the response to oxidative damage, adaptive mutation, and recombination. Cells lacking Pol II activity (polB delta 1 mutants) exhibited 5- to 10-fold-greater sensitivity to mode 1 killing by H2O2 compared with isogenic polB+ cells. Survival decreased by about 15-fold when polB mutants containing defective superoxide dismutase genes, sodA and sodB, were compared with polB+ sodA sodB mutants. Resistance to peroxide killing was restored following P1 transduction of polB cells to polB+ or by conjugation of polB cells with an F' plasmid carrying a copy of polB+. The rate at which Lac+ mutations arose in Lac- cells subjected to selection for lactose utilization, a phenomenon known as adaptive mutation, was increased threefold in polB backgrounds and returned to wild-type rates when polB cells were transduced to polB+. Following multiple passages of polB cells or prolonged starvation, a progressive loss of sensitivity to killing by peroxide was observed, suggesting that second-site suppressor mutations may be occurring with relatively high frequencies. The presence of suppressor mutations may account for the apparent lack of a mutant phenotype in earlier studies. A well-established polB strain, a dinA Mu d(Apr lac) fusion (GW1010), exhibited wild-type (Pol II+) sensitivity to killing by peroxide, consistent with the accumulation of second-site suppressor mutations. A high titer anti-Pol II polyclonal antibody was used to screen for the presence of Pol II in other bacteria and in the yeast Saccharomyces cerevisiae. Cross-reacting material was found in all gram-negative strains tested but was not detected in gram-positive strains or in S. cerevisiae. Induction of Pol II by nalidixic acid was observed in E. coli K-12, B, and C, in Shigella flexneri, and in Salmonella typhimurium.

  20. Comment on "Transient response of an acoustic medium by an excited submerged spherical shell" [J. Acoust. Soc. Am. 109(6), 2789-2796 (2001)].

    PubMed

    Bahari, Ako; Popplewell, Neil

    2015-05-01

    A closed form solution was derived previously for the response of a submerged spherical shell when the shell was excited by a spatially distributed, transient load at its inner surface [Zakout (2001). J. Acoust. Soc. Am. 109(6), 2789-2796]. Numerical results were presented for the modal and total acoustic pressures outside the empty sphere when the load's temporal history corresponded to the Heaviside step function. However, the result presented for the shell's "breathing" mode was inconsistent with these data as it corresponded to the delta Dirac (impulse) function. Furthermore, numerical results, which were given later for the total acoustic pressure responses, did not involve either of these excitations. Consequently the present objective is to rectify these anomalies.

  1. The MWA Transients Survey (MWATS).

    NASA Astrophysics Data System (ADS)

    Bell, M.; Murphy, T.; Kaplan, D. L.; Croft, S. D.; Hancock, P.; Rowlinson, A.; Wayth, R.; Gaensler, B.; Hurley-Walker, N.; Offringa, A.; Loi, C.; Bannister, K.; Trott, C.; Marquart, J.

    2017-01-01

    We propose the continuation of the MWA transients survey to search for and monitor low frequency transient and variable radio sources in the southern sky. This proposal is aimed at commensally utilising data from the GLEAM-X (G0008) project in semester 2017-A. The aim of this commensal data acquisition is to commission long baseline observations for transient science. In particular this will involve studying the impact of the ionosphere on calibration and imaging, and developing the techniques needed to produce science quality data products. The proposed drift scans with LST locking (see G0008 proposal) are particularly exciting as we can test image subtraction for transient and variable identification. This survey is targeted at studying objects such as AGN (intrinsic and extrinsic variability), long duration synchrotron emitters, pulsars and transients of unknown origin. The maps generated from this survey will be analysed with the Variables and Slow Transients (VAST) detection pipeline. The motivation for this survey is as follows: (i) To obtain temporal data on an extremely large and robust sample of low frequency sources to explore and quantify both intrinsic and extrinsic variability; (ii) To search and find new classes of low frequency radio transients that previously remained undetected and obscured from multi-wavelength discovery; (iii) To place rigorous statistics on the occurrence of both transients and variables prior to the Australian SKA era.

  2. Serial Assessment of Therapeutic Response to a New Radiosensitization Treatment, Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas, Type II (KORTUC II), in Patients with Stage I/II Breast Cancer Using Breast Contrast-Enhanced Magnetic Resonance Imaging

    PubMed Central

    Yaogawa, Shin; Ogawa, Yasuhiro; Morita-Tokuhiro, Shiho; Tsuzuki, Akira; Akima, Ryo; Itoh, Kenji; Morio, Kazuo; Yasunami, Hiroaki; Onogawa, Masahide; Kariya, Shinji; Nogami, Munenobu; Nishioka, Akihito; Miyamura, Mitsuhiko

    2015-01-01

    Background: We have developed a new radiosensitization treatment called Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas, Type II (KORTUC II). Using KORTUC II, we performed breast-conserving treatment (BCT) without any surgical procedure for elderly patients with breast cancer in stages I/II or patients refusing surgery. Since surgery was not performed, histological confirmation of the primary tumor region following KORTUC II treatment was not possible. Therefore, to precisely evaluate the response to this new therapy, a detailed diagnostic procedure is needed. The goal of this study was to evaluate the therapeutic response to KORTUC II treatment in patients with stage I/II breast cancer using annual breast contrast-enhanced (CE) magnetic resonance imaging (MRI). Methods: Twenty-one patients with stage I/II breast cancer who were elderly and/or refused surgery were enrolled in this study. All patients underwent MRI prior to and at 3 to 6 months after KORTUC II, and then approximately biannually thereafter. Findings from MRI were compared with those from other diagnostic modalities performed during the same time period. Results: KORTUC II was well tolerated, with minimal adverse effects. All of 21 patients showed a clinically complete response (cCR) on CE MRI. The mean period taken to confirm cCR on the breast CE MRI was approximately 14 months. The mean follow-up period for the patients was 61.9 months at the end of October 2014. Conclusions: The therapeutic effect of BCT using KORTUC II without surgery could be evaluated by biannual CE MRI evaluations. Approximately 14 months were required to achieve cCR in response to this therapy. PMID:26703733

  3. Role of transiently altered sarcolemmal membrane permeability and basic fibroblast growth factor release in the hypertrophic response of adult rat ventricular myocytes to increased mechanical activity in vitro.

    PubMed Central

    Kaye, D; Pimental, D; Prasad, S; Mäki, T; Berger, H J; McNeil, P L; Smith, T W; Kelly, R A

    1996-01-01

    One of the trophic factors that has been implicated in initiating or facilitating growth in response to increased mechanical stress in several tissues and cell types is basic fibroblast growth factor (bFGF; FGF-2). Although mammalian cardiac muscle cells express bFGF, it is not known whether it plays a role in mediating cardiac adaptation to increased load, nor how release of the cytosolic 18-kD isoform of bFGF would be regulated in response to increased mechanical stress. To test the hypothesis that increased mechanical activity induces transient alterations in sarcolemmal permeability that allow cytosolic bFGF to be released and subsequently to act as an autocrine and paracrine growth stimulus, we examined primary isolates of adult rat ventricular myocytes maintained in serum-free, defined medium that were continually paced at 3 Hz for up to 5 d. Paced myocytes, but not nonpaced control cells, exhibited a "hypertrophic" response, which was characterized by increases in the rate of phenylalanine incorporation, total cellular protein content, and cell size. These changes could be mimicked in control cells by exogenous recombinant bFGF and could be blocked in continually paced cells by a specific neutralizing anti-bFGF antibody. In addition, medium conditioned by continually paced myocytes contained significantly more bFGF measured by ELISA and more mitogenic activity for 3T3 cells, activity that could be reduced by a neutralizing anti-bFGF antibody. The hypothesis that transient membrane disruptions sufficient to allow release of cytosolic bFGF occur in paced myocytes was examined by monitoring the rate of uptake into myocytes from the medium of 10-kD dextran linked to fluorescein. Paced myocytes exhibited a significantly higher rate of fluoresceinlabeled dextran uptake. These data are consistent with the hypothesis that nonlethal, transient alterations in sarcolemmal membrane permeability with release of cytosolic bFGF is one mechanism by which increased

  4. Transients from initial conditions based on Lagrangian perturbation theory in N-body simulations II: the effect of the transverse mode

    SciTech Connect

    Tatekawa, Takayuki

    2014-04-01

    We study the initial conditions for cosmological N-body simulations for precision cosmology. In general, Zel'dovich approximation has been applied for the initial conditions of N-body simulations for a long time. These initial conditions provide incorrect higher-order growth. These error caused by setting up the initial conditions by perturbation theory is called transients. We investigated the impact of transient on non-Gaussianity of density field by performing cosmological N-body simulations with initial conditions based on first-, second-, and third-order Lagrangian perturbation theory in previous paper. In this paper, we evaluates the effect of the transverse mode in the third-order Lagrangian perturbation theory for several statistical quantities such as power spectrum and non-Gaussianty. Then we clarified that the effect of the transverse mode in the third-order Lagrangian perturbation theory is quite small.

  5. Transient thermoelectric supercooling: Isosceles current pulses from a response surface perspective and the performance effects of pulse cooling a heat generating mass

    NASA Astrophysics Data System (ADS)

    Piggott, Alfred J., III

    With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials

  6. Laughter as a social rejection cue: gelotophobia and transient cardiac responses to other persons' laughter and insult.

    PubMed

    Papousek, Ilona; Aydin, Nilüfer; Lackner, Helmut K; Weiss, Elisabeth M; Bühner, Markus; Schulter, Günter; Charlesworth, Canice; Freudenthaler, H Harald

    2014-11-01

    Other persons' laughter, normally perceived as a signal that persons are friendly and inviting others to approach, can also be perceived as a cue of social rejection. In this study, prerecorded laughter was placed in a realistic and personally relevant context, and participants' responses were related to gelotophobia, a trait predisposing to perceiving laughter as a cue of social rejection. Individuals with gelotophobia showed marked heart rate deceleration in response to the laughter stimulus, possibly indicating a "freezing-like" response. Moreover, cardiac responses to anger provocation by overtly insulting statements indicated heightened aggressive anger in response to cumulated social threat. The study adds to recent research showing specific cardiac responses to social rejection and to the literature on social rejection sensitivity by demonstrating the value of using well interpretable physiological measures in this research context.

  7. Energy conservation in the transient response of nonlinear beam vibration problems subjected to pulse loading - A numerical approach

    NASA Technical Reports Server (NTRS)

    Moyer, E. T., Jr.

    1984-01-01

    The nonlinear vibration response of a double cantilevered beam subjected to pulse loading over a central sector is studied. The initial response is generated in detail to ascertain the energetics of the response. The total energy is used as a gauge of the stability and accuracy of the solution. It is shown that to obtain accurate and stable initial solutions an extremely high spatial and time resolution is required. This requirement was only evident through an examination of the energy of the system. It is proposed, therefore, to use the total energy of the system as a necessary stability and accuracy criterion for the nonlinear response of conservative systems. The results also demonstrate that even for moderate nonlinearities, the effects of membrane forces have a significant influence on the system. It is also shown that while the fundamental response is contained in a first mode envelope, the fluctuations caused by the higher order modes must be resolved.

  8. Fast algorithm for transient current through open quantum systems

    NASA Astrophysics Data System (ADS)

    Cheung, King Tai; Fu, Bin; Yu, Zhizhou; Wang, Jian

    2017-03-01

    Transient current calculation is essential to study the response time and capture the peak transient current for preventing meltdown of nanochips in nanoelectronics. Its calculation is known to be extremely time consuming with the best scaling T N3 where N is the dimension of the device and T is the number of time steps. The dynamical response of the system is usually probed by sending a steplike pulse and monitoring its transient behavior. Here, we provide a fast algorithm to study the transient behavior due to the steplike pulse. This algorithm consists of two parts: algorithm I reduces the computational complexity to T0N3 for large systems as long as T II employs the fast multipole technique and achieves scaling T0N3 whenever T transient problems including magnetic tunneling junctions and ferroelectric tunneling junctions.

  9. Steady-state characteristics and transient response of MgZnO-based metal-semiconductor-metal solar-blind ultraviolet photodetector with three types of electrode structures.

    PubMed

    Wang, Ping; Zhen, Qinghong; Tang, Qing; Yang, Yintang; Guo, Lixin; Ding, Kai; Huang, Feng

    2013-07-29

    Detailed studies of MgZnO-based metal-semiconductor-metal (MSM) solar-blind ultraviolet photodetector with different electrode structures are performed. A two-dimensional physical model is established based on the Poisson's equation and time-dependent continuity equations, which is verified by our experimental data of conventional electrode MSM detector. The steady-state characteristics and transient response of semicircular and triangular electrode MSM detectors are also investigated by this model. Compared with the conventional electrode, semicircular and triangular electrode devices exhibit a substantial improvement on the photocurrent. At a bias of 10 V, the steady-state saturated photocurrents for semicircular and triangular electrode devices are 14.69 nA and 24.37 nA respectively, corresponding to a 20.5% and 100% increase over the conventional electrode detector. Meanwhile, the transient peak photocurrents reach 31.38 nA and 52.09 nA respectively, both of which are notably larger than that of conventional device.

  10. ENAC1, a NAC transcription factor, is an early and transient response regulator induced by abiotic stress in rice (Oryza sativa L.).

    PubMed

    Sun, Hui; Huang, Xi; Xu, Xingjun; Lan, Hongxia; Huang, Ji; Zhang, Hong-Sheng

    2012-10-01

    The plant-specific NAC (NAM, ATAF, and CUC)-domain proteins play important roles in plant development and stress responses. In this research, a full-length cDNA named ENAC1 (early NAC-domain protein induced by abiotic stress 1) was isolated from rice. ENAC1 possess one NAC domain in the N-terminus. Comparative time-course expression analysis indicated that ENAC1 expression, similar with OsDREB1A, was induced very quickly by various abiotic stresses including salt, drought, cold, and exogenous abscisic acid. However, the induction of ENAC1 by abiotic stress was transient and lasted up to 3 h, whereas that of OsDREB1A maintained longer. The promoter sequence of ENAC1 harbors several cis-elements including ABA response elements, but the well-known dehydration responsive element/C-repeat element is absent. The ENAC1-GFP (green fluorescent protein) fusion protein was localized in the nucleus of rice protoplast cell. Yeast hybrid assays revealed that ENAC1 was a transcription activator and bound to NAC recognition sequence (NACRS). Co-expression analysis suggested that ENAC1 co-expressed with a number of stress-related genes. Taken together, ENAC1 may be an early transcription activator of stress responses and function in the regulation of NACRS-mediated gene expression under abiotic stress.

  11. Cellular and biomolecular responses of human ovarian cancer cells to cytostatic dinuclear platinum(II) complexes.

    PubMed

    Lin, Miaoxin; Wang, Xiaoyong; Zhu, Jianhui; Fan, Damin; Zhang, Yangmiao; Zhang, Junfeng; Guo, Zijian

    2011-03-01

    Polynuclear platinum(II) complexes represent a class of potential anticancer agents that have shown promising pharmacological properties in preclinical studies. The nature of cellular responses induced by these complexes, however, is poorly understood. In this research, the cellular responses of human ovarian cancer COC1 cells to dinuclear platinum(II) complexes {[cis-Pt(NH₃)₂Cl]₂L¹}(NO₃)₂ (1) and {[cis-Pt(NH₃)₂Cl]₂L²}(NO₃)₂ (2) (L¹ = α,α'-diamino-p-xylene, L² = 4,4'-methylenedianiline) has been studied using cisplatin as a reference. The effect of platinum complexes on the proliferation, death mode, mitochondrial membrane potential, and cell cycle progression has been examined by MTT assay and flow cytometry. The activation of cell cycle checkpoint kinases (CHK1/2), extracellular signal-regulated kinases (ERK1/2), and p38 mitogen-activated protein kinase (p38 MAPK) of the cells by the complexes has also been analyzed using phospho-specific flow cytometry. Complex 1 is more cytotoxic than complex 2 and cisplatin at most concentrations; complex 2 and cisplatin are comparably cytotoxic. These complexes kill the cells through an apoptotic or apoptosis-like pathway characterized by exposure of phosphatidylserine and dissipation of mitochondrial membrane potential. Complex 1 shows the strongest inductive effect on the morphological changes of the cells, followed by cisplatin and complex 2. Complexes 1 and 2 arrest the cell cycle in G2 or M phase, while cisplatin arrests the cell cycle in S phase. The influence of these complexes on CHK1/2, ERK1/2, and p38 MAPK varies with the dose of the drugs or reaction time. Activation of phospho-ERK1/2 and phospho-p38 MAPK by these complexes is closely related to the cytostatic activity. The results demonstrate that dinuclear platinum(II) complexes can induce some cellular responses different from those caused by cisplatin.

  12. Aquifer response to stream-stage and recharge variations. II. Convolution method and applications

    USGS Publications Warehouse

    Barlow, P.M.; DeSimone, L.A.; Moench, A.F.

    2000-01-01

    In this second of two papers, analytical step-response functions, developed in the companion paper for several cases of transient hydraulic interaction between a fully penetrating stream and a confined, leaky, or water-table aquifer, are used in the convolution integral to calculate aquifer heads, streambank seepage rates, and bank storage that occur in response to streamstage fluctuations and basinwide recharge or evapotranspiration. Two computer programs developed on the basis of these step-response functions and the convolution integral are applied to the analysis of hydraulic interaction of two alluvial stream-aquifer systems in the northeastern and central United States. These applications demonstrate the utility of the analytical functions and computer programs for estimating aquifer and streambank hydraulic properties, recharge rates, streambank seepage rates, and bank storage. Analysis of the water-table aquifer adjacent to the Blackstone River in Massachusetts suggests that the very shallow depth of water table and associated thin unsaturated zone at the site cause the aquifer to behave like a confined aquifer (negligible specific yield). This finding is consistent with previous studies that have shown that the effective specific yield of an unconfined aquifer approaches zero when the capillary fringe, where sediment pores are saturated by tension, extends to land surface. Under this condition, the aquifer's response is determined by elastic storage only. Estimates of horizontal and vertical hydraulic conductivity, specific yield, specific storage, and recharge for a water-table aquifer adjacent to the Cedar River in eastern Iowa, determined by the use of analytical methods, are in close agreement with those estimated by use of a more complex, multilayer numerical model of the aquifer. Streambank leakance of the semipervious streambank materials also was estimated for the site. The streambank-leakance parameter may be considered to be a general (or lumped

  13. The Mysterious Transient ROTSE3 J115649.1+542726 is an Extremely Luminous Type II SN at z = 0.21

    NASA Astrophysics Data System (ADS)

    Chornock, R.; Miller, A. A.; Perley, D. A.; Bloom, J. S.

    2008-08-01

    We report on further spectroscopic observations of the transient ROTSE3 J115649.1+542726 discovered by Yuan et al. (ATEL #1515) and followed up by several groups (ATEL #1524, ATEL #1576, ATEL #1578, and ATEL #1593). We observed the object for 840 s using the Low-Resolution Imaging Spectrometer (LRIS; Oke et al. 1995) on the Keck I 10-m telescope on 2008 Aug 3.25 UT. Our initial observations of this object (ATEL #1576) showed a blue and largely featureless spectrum, but at later epochs several unidentified weak spectral features appeared (ATEL #1576 and ATEL #1593).

  14. Transient regional climate change: analysis of the summer climate response in a high-resolution, century-scale, ensemble experiment over the continental United States

    PubMed Central

    Diffenbaugh, Noah S.; Ashfaq, Moetasim; Scherer, Martin

    2013-01-01

    Integrating the potential for climate change impacts into policy and planning decisions requires quantification of the emergence of sub-regional climate changes that could occur in response to transient changes in global radiative forcing. Here we report results from a high-resolution, century-scale, ensemble simulation of climate in the United States, forced by atmospheric constituent concentrations from the Special Report on Emissions Scenarios (SRES) A1B scenario. We find that 21st century summer warming permanently emerges beyond the baseline decadal-scale variability prior to 2020 over most areas of the continental U.S. Permanent emergence beyond the baseline annual-scale variability shows much greater spatial heterogeneity, with emergence occurring prior to 2030 over areas of the southwestern U.S., but not prior to the end of the 21st century over much of the southcentral and southeastern U.S. The pattern of emergence of robust summer warming contrasts with the pattern of summer warming magnitude, which is greatest over the central U.S. and smallest over the western U.S. In addition to stronger warming, the central U.S. also exhibits stronger coupling of changes in surface air temperature, precipitation, and moisture and energy fluxes, along with changes in atmospheric circulation towards increased anticylonic anomalies in the mid-troposphere and a poleward shift in the mid-latitude jet aloft. However, as a fraction of the baseline variability, the transient warming over the central U.S. is smaller than the warming over the southwestern or northeastern U.S., delaying the emergence of the warming signal over the central U.S. Our comparisons with observations and the Coupled Model Intercomparison Project Phase 3 (CMIP3) ensemble of global climate model experiments suggest that near-term global warming is likely to cause robust sub-regional-scale warming over areas that exhibit relatively little baseline variability. In contrast, where there is greater

  15. Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis

    PubMed Central

    Castaldi, E.; Cicchini, G. M.; Cinelli, L.; Rizzo, S.; Morrone, M. C.

    2016-01-01

    Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them. No subject showed any improvement of contrast sensitivity in either eye when not using the Argus II. Before the implant, the Blood Oxygenation Level Dependent (BOLD) activity in V1 and the lateral geniculate nucleus (LGN) was very weak or absent. Surprisingly, after prolonged use of Argus II, BOLD responses to visual input were enhanced. This is, to our knowledge, the first study tracking the neural changes of visual areas in patients after retinal implant, revealing a capacity to respond to restored visual input even after years of deprivation. PMID:27780207

  16. Flexible designs for phase II comparative clinical trials involving two response variables.

    PubMed

    Bersimis, S; Sachlas, A; Papaioannou, T

    2015-01-30

    The aim of phase II clinical trials is to determine whether an experimental treatment is sufficiently promising and safe to justify further testing. The need for reduced sample size arises naturally in phase II clinical trials owing to both technical and ethical reasons, motivating a significant part of research in the field during recent years, while another significant part of the research effort is aimed at more complex therapeutic schemes that demand the consideration of multiple endpoints to make decisions. In this paper, our attention is restricted to phase II clinical trials in which two treatments are compared with respect to two dependent dichotomous responses proposing some flexible designs. These designs permit the researcher to terminate the clinical trial when high rates of favorable or unfavorable outcomes are observed early enough requiring in this way a small number of patients. From the mathematical point of view, the proposed designs are defined on bivariate sequences of multi-state trials, and the corresponding stopping rules are based on various distributions related to the waiting time until a certain number of events appear in these sequences. The exact distributions of interest, under a unified framework, are studied using the Markov chain embedding technique, which appears to be very useful in clinical trials for the sample size determination. Tables of expected sample size and power are presented. The numerical illustration showed a very good performance for these new designs.

  17. Stomatal dynamics and its importance to carbon gain in two rainforest Piper species : I. VPD effects on the transient stomatal response to lightflecks.

    PubMed

    Tinoco-Ojanguren, Clara; Pearcy, Robert W

    1993-06-01

    The effects of leaf-air vapor pressure deficit (VPD) on the transient and steady-state stomatal responses to photon flux density (PFD) were evaluated in Piper auritum, a pioneer tree, and Piper aequale, a shade tolerant shrub, that are both native to tropical forests at Los Tuxtlas, Veracruz, México. Under constant high-PFD conditions, the stomata of shade-acclimated plants of both species were sensitive to VPD, exhibiting a nearly uniform decrease in gs as VPD increased. Acclimation of P. auritum to high light increased the stomatal sensitivity to VPD that was sufflcient to cause a reduction in transpiration at high VPD's. At low PFD, where gs was already reduced, there was little additional absolute change with VPD for any species or growth condition. The stomatal response to 8-min duration lightflecks was strongly modulated by VPD and varied between the species and growth light conditions. In P. aequale shade plants, increased VPD had no effect on the extent of stomatal opening but caused the rate of closure after the lightfleck to be faster. Thus, the overall response to a lightfleck changed from hysteretic (faster opening than closure) to symmetric (similar opening and closing rates). Either high or low VPD caused gs not to return to the steady-state value present before the lightfleck. At high VPD the value after was considerably less than the value before whereas at low VPD the opposite occurred. Shade-acclimated plants of P. auritum showed only a small gs response to lightflecks, which was not affected by VPD. Under sunfleck regimes in the understory, the stomatal response of P. aequale at low VPD may function to enhance carbon gain by increasing the induction state. At high VPD, the shift in the response enhances water use efficiency but at the cost of reduced assimilation.

  18. A model of neurovascular coupling and the BOLD response PART II.

    PubMed

    Mathias, E J; Plank, M J; David, T

    2017-04-01

    A mathematical model is developed which describes a signalling mechanism of neurovascular coupling with a model of a pyramidal neuron and its corresponding fMRI BOLD response. In the first part of two papers (Part I) we described the integration of the neurovascular coupling unit extended to include a complex neuron model, which includes the important Na/K ATPase pump, with a model that provides a BOLD signal taking its input from the cerebral blood flow and the metabolic rate of oxygen consumption. We showed that this produced a viable signal in terms of initial dip, positive and negative BOLD signals. In this paper (PART II) our model predicts the variations of the BOLD response due to variations in neuronal activity and indicates that the BOLD signal could be used as an initial biomarker for neuronal dysfunction or variations in the perfusion of blood to the cerebral tissue. We have compared the simulated hypoxic BOLD response to experimental BOLD signals observed in the hippocampus during hypoxia showing good agreement. This approach of combined quantitative modelling of neurovascular coupling response and its BOLD response will enable more specific assessment of a brain region.

  19. Parecoxib is neuroprotective in spontaneously hypertensive rats after transient middle cerebral artery occlusion: a divided treatment response?

    PubMed Central

    Kelsen, Jesper; Kjær, Katrine; Chen, Gang; Pedersen, Michael; Røhl, Lisbeth; Frøkiær, Jørgen; Nielsen, Søren; Nyengaard, Jens R; Rønn, Lars Christian B

    2006-01-01

    Background Anti-inflammatory treatment affects ischemic damage and neurogenesis in rodent models of cerebral ischemia. We investigated the potential benefit of COX-2 inhibition with parecoxib in spontaneously hypertensive rats (SHRs) subjected to transient middle cerebral artery occlusion (tMCAo). Methods Sixty-four male SHRs were randomized to 90 min of intraluminal tMCAo or sham surgery. Parecoxib (10 mg/kg) or isotonic saline was administered intraperitoneally (IP) during the procedure, and twice daily thereafter. Nineteen animals were euthanized after 24 hours, and each hemisphere was examined for mRNA expression of pro-inflammatory cytokines and COX enzymes by quantitative RT-PCR. Twenty-three tMCAo animals were studied with diffusion and T2 weighted MRI within the first 24 hours, and ten of the SHRs underwent follow-up MRI six days later. Thirty-three SHRs were given 5-bromo-2'-deoxy-uridine (BrdU) twice daily on Day 4 to 7 after tMCAo. Animals were euthanized on Day 8 and the brains were studied with free-floating immunohistochemistry for activated microglia (ED-1), hippocampal granule cell BrdU incorporation, and neuronal nuclei (NeuN). Infarct volume estimation was done using the 2D nucleator and Cavalieri principle on NeuN-stained coronal brain sections. The total number of BrdU+ cells in the dentate gyrus (DG) of the hippocampus was estimated using the optical fractionator. Results We found a significant reduction in infarct volume in parecoxib treated animals one week after tMCAo (p < 0.03). Cortical ADC values in the parecoxib group were markedly less increased on Day 8 (p < 0.01). Interestingly, the parecoxib treated rats were segregated into two subgroups, suggesting a responder vs. non-responder phenomenon. We found indications of mRNA up-regulation of IL-1β, IL-6, TNF-α and COX-2, whereas COX-1 remained unaffected. Hippocampal granule cell BrdU incorporation was not affected by parecoxib treatment. Presence of ED-1+ activated microglia in the

  20. The potentiating effect of calcitonin gene-related peptide on transient receptor potential vanilloid-1 activity and the electrophysiological responses of rat trigeminal neurons to nociceptive stimuli.

    PubMed

    Chatchaisak, Duangthip; Connor, Mark; Srikiatkhachorn, Anan; Chetsawang, Banthit

    2017-02-15

    Growing evidence suggests that calcitonin gene-related peptide (CGRP) participates in trigeminal nociceptive responses. However, the role of CGRP in sensitization or desensitization of nociceptive transduction remains poorly understood. In this study, we sought to further investigate the CGRP-induced up-regulation of transient receptor potential vanilloid-1 (TRPV1) and the responses of trigeminal neurons to nociceptive stimuli. Rat trigeminal ganglion (TG) organ cultures and isolated trigeminal neurons were incubated with CGRP. An increase in TRPV1 levels was observed in CGRP-incubated TG organ cultures. CGRP potentiated capsaicin-induced increase in phosphorylated CaMKII levels in the TG organ cultures. The incubation of the trigeminal neurons with CGRP significantly increased the inward currents in response to capsaicin challenge, and this effect was inhibited by co-incubation with the CGRP receptor antagonist, BIBN4068BS or the inhibitor of protein kinase A, H-89. These findings reveal that CGRP acting on trigeminal neurons may play a significant role in facilitating cellular events that contribute to the peripheral sensitization of the TG in nociceptive transmission.

  1. Transient Cannabinoid Receptor 2 Blockade during Immunization Heightens Intensity and Breadth of Antigen-specific Antibody Responses in Young and Aged mice

    PubMed Central

    Dotsey, Emmanuel; Ushach, Irina; Pone, Egest; Nakajima, Rie; Jasinskas, Algis; Argueta, Donovan A.; Dillon, Andrea; DiPatrizio, Nicholas; Davies, Huw; Zlotnik, Albert; Crompton, Peter D.; Felgner, Philip L.

    2017-01-01

    The hallmark of vaccines is their ability to prevent the spread of infectious pathogens and thereby serve as invaluable public health tool. Despite their medical relevance, there is a gap in our understanding of the physiological factors that mediate innate and adaptive immune response to vaccines. The endocannabinoid (eCB) system is a critical modulator of homeostasis in vertebrates. Our results indicate that macrophages and dendritic cells produce the endocannabinoid, 2-arachidonoyl-sn-glycerol (2-AG) upon antigen activation. We have also established that 2-AG levels are upregulated in the serum and in the lymph node of mice during vaccination. We hypothesized that the intrinsic release of eCBs from immune cells during activation by pathogenic antigens mitigate inflammation, but also suppress overall innate and adaptive immune response. Here we demonstrate, for the first time, that transient administration of the cannabinoid receptor 2 antagonist AM630 (10 mg/kg) or inverse agonist JTE907 (3 mg/kg) during immunization heightens the intensity and breadth of antigen-specific immune responses in young and aged mice through the upregulation of immunomodulatory genes in secondary lymphoid tissues. PMID:28209996

  2. Glucose triggers different global responses in yeast, depending on the strength of the signal, and transiently stabilizes ribosomal protein mRNAs.

    PubMed

    Yin, Zhikang; Wilson, Séan; Hauser, Nicole C; Tournu, Helene; Hoheisel, Jörg D; Brown, Alistair J P

    2003-05-01

    Glucose exerts profound effects upon yeast physiology. In general, the effects of high glucose concentrations (>1%) upon Saccharomyces cerevisiae have been studied. In this paper, we have characterized the global responses of yeast cells to very low (0.01%), low (0.1%) and high glucose signals (1.0%) by transcript profiling. We show that yeast is more sensitive to very low glucose signals than was previously thought, and that yeast displays different responses to these different glucose signals. Genes involved in central metabolic pathways respond rapidly to very low glucose signals, whereas genes involved in the biogenesis of cytoplasmic ribosomes generally respond only to glucose concentrations of> 0.1%. We also show that cytoplasmic ribosomal protein mRNAs are transiently stabilized by glucose, indicating that both transcriptional and post-transcriptional mechanisms combine to accelerate the accumulation of ribosomal protein mRNAs. Presumably, this facilitates rapid ribosome biogenesis after exposure to glucose. However, our data indicate that yeast activates ribosome biogenesis only when sufficient glucose is available to make this metabolic investment worthwhile. In contrast, the regulation of metabolic functions in response to very low glucose signals presumably ensures that yeast can exploit even minute amounts of this preferred nutrient.

  3. A Collapsin Response Mediator Protein 2 Isoform Controls Myosin II-Mediated Cell Migration and Matrix Assembly by Trapping ROCK II

    PubMed Central

    Morgan-Fisher, Marie; Wait, Robin; Couchman, John R.; Wewer, Ulla M.

    2012-01-01

    Collapsin response mediator protein 2 (CRMP-2) is known as a regulator of neuronal polarity and differentiation through microtubule assembly and trafficking. Here, we show that CRMP-2 is ubiquitously expressed and a splice variant (CRMP-2L), which is expressed mainly in epithelial cells among nonneuronal cells, regulates myosin II-mediated cellular functions, including cell migration. While the CRMP-2 short form (CRMP-2S) is recognized as a substrate of the Rho-GTP downstream kinase ROCK in neuronal cells, a CRMP-2 complex containing 2L not only bound the catalytic domain of ROCK II through two binding domains but also trapped and inhibited the kinase. CRMP-2L protein levels profoundly affected haptotactic migration and the actin-myosin cytoskeleton of carcinoma cells as well as nontransformed epithelial cell migration in a ROCK activity-dependent manner. Moreover, the ectopic expression of CRMP-2L but not -2S inhibited fibronectin matrix assembly in fibroblasts. Underlying these responses, CRMP-2L regulated the kinase activity of ROCK II but not ROCK I, independent of GTP-RhoA levels. This study provides a new insight into CRMP-2 as a controller of myosin II-mediated cellular functions through the inhibition of ROCK II in nonneuronal cells. PMID:22431514

  4. Matrix method of determining the longitudinal-stability coefficients and frequency response of an aircraft from transient flight data

    NASA Technical Reports Server (NTRS)

    Donegan, James J; Pearson, Henry A

    1952-01-01

    A matrix method is presented for determining the longitudinal-stability coefficients and frequency response of an aircraft from arbitrary maneuvers. The method is devised so that it can be applied to time-history measurements of combinations of such simple quantities as angle of attack, pitching velocity, load factor, elevator angle, and hinge moment to obtain the over-all coefficients. Although the method has been devised primarily for the evaluation of stability coefficients which are of primary interest in most aircraft loads and stability studies, it can be used also, with a simple additional computation, to determine the frequency-response characteristics. The entire procedure can be applied or extended to other problems which can be expressed by linear differential equations.

  5. Response of hydrothermal system to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise

    NASA Astrophysics Data System (ADS)

    Taira, Taka'aki; Brenguier, Florent

    2016-10-01

    Time-lapse monitoring of seismic velocity at volcanic areas can provide unique insight into the property of hydrothermal and magmatic fluids and their temporal variability. We established a quasi real-time velocity monitoring system by using seismic interferometry with ambient noise to explore the temporal evolution of velocity in the Lassen Volcanic Center, Northern California. Our monitoring system finds temporal variability of seismic velocity in response to stress changes imparted by an earthquake and by seasonal environmental changes. Dynamic stress changes from a magnitude 5.7 local earthquake induced a 0.1 % velocity reduction at a depth of about 1 km. The seismic velocity susceptibility defined as ratio of seismic velocity change to dynamic stress change is estimated to be about 0.006 MPa-1, which suggests the Lassen hydrothermal system is marked by high-pressurized hydrothermal fluid. By combining geodetic measurements, our observation shows that the long-term seismic velocity fluctuation closely tracks snow-induced vertical deformation without time delay, which is most consistent with an hydrological load model (either elastic or poroelastic response) in which surface loading drives hydrothermal fluid diffusion that leads to an increase of opening of cracks and subsequently reductions of seismic velocity. We infer that heated-hydrothermal fluid in a vapor-dominated zone at a depth of 2-4 km range is responsible for the long-term variation in seismic velocity[Figure not available: see fulltext.

  6. Transient inflammatory response mediated by interleukin-1β is required for proper regeneration in zebrafish fin fold

    PubMed Central

    Hasegawa, Tomoya; Hall, Christopher J; Crosier, Philip S; Abe, Gembu; Kawakami, Koichi; Kudo, Akira; Kawakami, Atsushi

    2017-01-01

    Cellular responses to injury are crucial for complete tissue regeneration, but their underlying processes remain incompletely elucidated. We have previously reported that myeloid-defective zebrafish mutants display apoptosis of regenerative cells during fin fold regeneration. Here, we found that the apoptosis phenotype is induced by prolonged expression of interleukin 1 beta (il1b). Myeloid cells are considered to be the principal source of Il1b, but we show that epithelial cells express il1b in response to tissue injury and initiate the inflammatory response, and that its resolution by macrophages is necessary for survival of regenerative cells. We further show that Il1b plays an essential role in normal fin fold regeneration by regulating expression of regeneration-induced genes. Our study reveals that proper levels of Il1b signaling and tissue inflammation, which are tuned by macrophages, play a crucial role in tissue regeneration. DOI: http://dx.doi.org/10.7554/eLife.22716.001 PMID:28229859

  7. NRF2 and the Phase II Response in Acute Stress Resistance Induced by Dietary Restriction

    PubMed Central

    Hine, Christopher M.; Mitchell, James R.

    2013-01-01

    Dietary restriction (DR) as a means to increase longevity is well-established in a number of model organisms from yeast to primates. DR also improves metabolic fitness and increases resistance to acute oxidative, carcinogenic and toxicological stressors - benefits with more immediate potential for clinical translation than increased lifespan. While the detailed mechanism of DR action remains unclear, a conceptual framework involving an adaptive, or hormetic response to the stress of nutrient/energy deprivation has been proposed. A key prediction of the hormesis hypothesis of DR is that beneficial adaptations occur in response to an increase in reactive oxygen/nitrogen species (ROS). These ROS may be derived either from increased mitochondrial respiration or increased xenobiotic metabolism in the case of some DR mimetics. This review will focus on the potential role of the redox-sensing transcription factor NF-E2-related factor 2 (NRF2) and its control of the evolutionarily conserved antioxidant/redox cycling and detoxification systems, collectively known as the Phase II response, in the adaptive response to DR. PMID:23505614

  8. 4-oxo-2-nonenal (4-ONE): evidence of transient receptor potential ankyrin 1-dependent and -independent nociceptive and vasoactive responses in vivo.

    PubMed

    Graepel, Rabea; Fernandes, Elizabeth S; Aubdool, Aisah A; Andersson, David A; Bevan, Stuart; Brain, Susan D

    2011-04-01

    This study explores the in vivo effects of the proposed transient receptor potential ankyrin 1 (TRPA1) agonist 4-oxo-2-nonenal (4-ONE). Pharmacological inhibitors and genetically modified mice were used to investigate the ability of 4-ONE to act via TRPA1 receptors and possible mechanisms involving transient receptor potential vanilloid 1 (TRPV1). We hypothesized that 4-ONE activates sensory nerves, via TRPA1 or possibly TRPV1, and thus triggers mechanical hyperalgesia, edema formation, and vasodilatation in mice. An automated dynamic plantar aesthesiometer was used to determine hind paw withdrawal thresholds, and a laser Doppler flowmeter was used to measure skin blood flow. Edema formation was determined by measuring paw weights and thickness. 4-ONE (10 nmol) triggers unilateral mechanical hyperalgesia, edema formation, and vasodilatation in mice and is shown here to exhibit TRPA1-dependent and -independent effects. Neurogenic vasodilatation and mechanical hyperalgesia at 0.5 h postinjection were significantly greater in TRPA1 wild-type (WT) mice compared with TRPA1 knockout (KO) mice. Edema formation throughout the time course as well as mechanical hyperalgesia from 1 to 4 h postinjection were similar in WT and TRPA1 KO mice. Studies involving TRPV1 KO mice revealed no evidence of TRPV1 involvement or interactions between TRPA1 and TRPV1 in mediating the in vivo effects of 4-ONE. Previously, 4-ONE was shown to be a potent TRPA1 agonist in vitro. We demonstrate its ability to mediate vasodilatation and certain nociceptive effects in vivo. These data indicate the potential of TRPA1 as an oxidant sensor for vasodilator responses in vivo. However, 4-ONE also triggers TRPA1-independent effects that relate to edema formation and pain.

  9. Rapid Spectroscopy of Elusive Transients and Young Supernovae

    NASA Astrophysics Data System (ADS)

    Kasliwal, Mansi; Cao, Yi; Kulkarni, Shri; van Kerkwijk, Marten; Gal-Yam, Avishay; Cooke, Jeffrey; Yaron, Ofer; Ofek, Eran; Goobar, Ariel; Sollerman, Jesper; Amanullah, Rahman; Cenko, Bradley; Quimby, Robert; Bernard, Stephanie; Pritchard, Tyler; Horesh, Assaf; Arcavi, Iair; Valenti, Stefano; Howell, Andy; Singer, Leo; Wozniak, Przemek; Vestrand, Tom

    2014-08-01

    The intermediate Palomar Transient Factory (iPTF) is systematically exploring the optical transient sky. We focus on short timescales to optimize the survey discovery rate of very young supernovae and rare ephemeral transients. Building on the PTF legacy, our new iPTF software pipeline is geared towards automated alerts for follow-up within hours of discovery. Rapid response spectroscopy of iPTF transients will unveil (i) progenitors of supernovae: shock cooling, companion, circumstellar material properties, (ii) origin of recently discovered but poorly understood new classes of gap transients, and (iii) redshifts of relativistic afterglows discovered in seventy square degree searches or even independent of a high energy trigger. These unique physical insights into the nature of the explosion cannot be gained from late-time observations. Here, we request a dedicated iPTF-Gemini program for rapid spectroscopy. We request a total of ten target-of-opportunity triggers on the Gemini-South and Gemini-North telescopes (10.83 hours). The rapid Gemini data will be complemented with panchromatic observations: radio with JVLA and CARMA, UV/X-ray with the Swift satellite and long-term optical/near-IR studies with Palomar/Magellan/Keck.

  10. Protective immune response in mice induced by a suicidal DNA vaccine encoding NTPase-II gene of Toxoplasma gondii.

    PubMed

    Zheng, Lina; Hu, Yue; Hua, Qianqian; Luo, Fangjun; Xie, Guizhen; Li, Xiangzhi; Lin, Jiaxin; Wan, Yujing; Ren, Shoufeng; Pan, Changwang; Tan, Feng

    2017-02-01

    DNA-based alphaviral RNA replicon vectors, also called suicidal DNA vectors, have been employed to alleviate biosafety concerns attribution to its ability to induce apoptotic cell death of the transfected cells. Toxoplasma gondii nucleoside triphosphate hydrolase-II (TgNTPase-II), which facilitates the parasite to salvage purines from the host cell for survival and replication, have been demonstrated to be a potential vaccine candidate for toxoplasmosis. Herein, we evaluated the immunogenic potential of a suicidal DNA vaccine encoding TgNTPase-II gene, pDREP-TgNTPase-II, delivered intramuscularly in combination with electroporation. Immunization of mice with pDREP-TgNTPase-II elicited specific humoral responses, with high IgG antibody titers and a mixed IgG1/IgG2a response. The cellular immune response was associated with high level production of IFN-γ, IL-2, IL-10 cytokines and low level IL-4 production as well as the increase of the percentage of CD8+ T cells, indicating that a Th1 predominant response was elicited. Furthermore, mice vaccinated with this suicidal DNA vaccine displayed partial protection against acute infection with the virulent RH strain as well as chronic infection with PRU cyst, which shows 77.7% and 71.4% reduction in brain cyst burden in comparison to PBS and pDREP-eGFP control group, respectively. Based on the cellular and antibody responses, the suicidal DNA vaccine elicited a Th1-predominant immune response against T. gondii challenge.

  11. Latent inhibition-related dopaminergic responses in the nucleus accumbens are disrupted following neonatal transient inactivation of the ventral subiculum.

    PubMed

    Meyer, Francisca F; Louilot, Alain

    2011-06-01

    Schizophrenia would result from a defective connectivity between several integrative regions as a consequence of neurodevelopmental failure. Various anomalies reminiscent of early brain development disturbances have been observed in patients' left ventral subiculum of the hippocampus (SUB). Numerous data support the hypothesis of a functional dopaminergic dysregulation in schizophrenia. The common target structure for the action of antipsychotics appears to be a subregion of the ventral striatum, the dorsomedial shell part of the nucleus accumbens. Latent inhibition, a cognitive marker of interest for schizophrenia, has been found to be disrupted in acute patients. The present study set out to investigate the consequences of a neonatal functional inactivation of the left SUB by tetrodotoxin (TTX) in 8-day-old rats for the latent inhibition-related dopaminergic responses, as monitored by in vivo voltammetry in freely moving adult animals (11 weeks) in the left core and dorsomedial shell parts of the nucleus accumbens in an olfactory aversion procedure. Results obtained during the retention session of a three-stage latent inhibition protocol showed that the postnatal unilateral functional blockade of the SUB was followed in pre-exposed TTX-conditioned adult rats by a disruption of the behavioral expression of latent inhibition and induced a total and a partial reversal of the latent inhibition-related dopaminergic responses in the dorsomedial shell and core parts of the nucleus accumbens, respectively. The present data suggest that neonatal inactivation of the SUB has more marked consequences for the dopaminergic responses recorded in the dorsomedial shell part, than in the core part of the nucleus accumbens. These findings may provide new insight into the pathophysiology of schizophrenia.

  12. Shallow landslide stability computation using a distributed transient response model for susceptibility assessment and validation. A case study from Ribeira Quente valley (S. Miguel island, Azores)

    NASA Astrophysics Data System (ADS)

    Amaral, P.; Marques, R.; Zêzere, J. L.; Marques, F.; Queiroz, G.

    2009-04-01

    In the last 15 years, several heavy rainstorms have occurred in Povoação County (S. Miguel Island, Azores), namely in the Ribeira Quente Valley. These rainfall events have triggered hundreds of shallow landslides that killed tens of people and have been responsible for direct and indirect damages amounting to tens of millions of Euros. On the 6th March 2005 an intense rainfall episode, up to 160 mm of rain in less than 24 h, triggered several shallow landslides that caused 3 victims and damaged/blocked roads. The Ribeira Quente Valley has an area of about 9.5 km2 and is mainly constituted by pyroclastic materials (pumice ash and lapilli), that were produced by the Furnas Volcano explosive eruptions. To provide an assessment of slope-failure conditions for the 6th March 2005 rainfall event, it was applied a distributed transient response model for slope stability analysis. The adopted methodology is a modified version of Iversońs (2000) transient response model, which couple an infinite slope stability analysis with an analytic solution of the Richard's equation for vertical water infiltration in quasi-saturated soil. The validation was made on two different scales: (1) at a slope scale, using two distinct test sites where landslides were triggered; and (2) at the basin scale, using the entire landslide database and generalizing the modeling input parameters for the regional spatialization of results. At the slope scale, the obtained results were very accurate, and it was possible to predict the precise time of the slope failures. At the basin scale, the obtained results were very conservative, even though the model predicted all the observed landslide locations, in the 23.7% of the area classified as untable at the time of the slope failures. This methodology revealed to be a reasonable tool for landslide forecast for both temporal and spatial distributions, on both slope and regional scales. In the future, the model components will be integrated into a GIS

  13. Granulocyte colony-stimulating factor (G-CSF) transiently suppresses mitogen-stimulated T-cell proliferative response

    PubMed Central

    Reyes, E; García-Castro, I; Esquivel, F; Hornedo, J; Cortes-Funes, H; Solovera, J; Alvarez-Mon, M

    1999-01-01

    Granulocyte colony-stimulation factor (G-CSF) is a cytokine that selectively promotes growth and maturation of neutrophils and may modulate the cytokine response to inflammatory stimuli. The purpose of this study was to examine the effect of G-CSF on ex vivo peripheral blood mononuclear cell (PBMC) functions. Ten patients with breast cancer were included in a clinical trial in which r-metHuG-CSF was administrered daily for 5 days to mobilize peripheral blood stem cells. Ten healthy women were also included as controls. Our data show that G-CSF treatment induces an increase in peripheral blood leucocyte, neutrophil, lymphocyte and monocyte counts. We have found a modulation in the percentages of CD19+, CD45+CD14+, CD4+CD45RA+ and CD4+CD45RO+ cells in PBMC fractions during G-CSF treatment. We have also found a significant reduction in the proliferative response of PBMC to mitogenic stimulation that reverted 14 days after the fifth and the last dose of G-CSF. Furthermore, it was not associated with significant changes in the pattern of cytokine production. The mechanism of this immunoregulatory effect is probably indirect since G-CSF receptor has not been found in T lymphocytes. This mechanism and its potential clinical applications remain to be elucidated. © 1999 Cancer Research Campaign PMID:10390001

  14. Crystal structure of the Staphylococcus aureus pI258 CadC Cd(II)/Pb(II)/Zn(II)-responsive repressor.

    PubMed

    Ye, Jun; Kandegedara, Ashoka; Martin, Philip; Rosen, Barry P

    2005-06-01

    The Staphylococcus aureus plasmid pI258 cadCA operon encodes a P-type ATPase, CadA, that confers resistance to the heavy metals Cd(II), Zn(II), and Pb(II). Expression of this heavy-metal efflux pump is regulated by CadC, a homodimeric repressor that dissociates from the cad operator/promoter upon binding of Cd(II), Pb(II), or Zn(II). CadC is a member of the ArsR/SmtB family of metalloregulatory proteins. Here we report the X-ray crystal structure of CadC at 1.9 angstroms resolution. The dimensions of the protein dimer are approximately 30 angstroms by 40 angstroms by 70 angstroms. Each monomer contains six alpha-helices and a three-stranded beta-sheet. Helices 4 and 5 form a classic helix-turn-helix motif that is the putative DNA binding region. The alpha1 helix of one monomer crosses the dimer to approach the alpha4 helix of the other monomer, consistent with the previous proposal that these two regulatory metal binding sites for the inducer cadmium or lead are each formed by Cys-7 and Cys-11 from the N terminus of one monomer and Cys-58 and Cys-60 of the other monomer. Two nonregulatory metal binding sites containing zinc are formed between the two antiparallel alpha6 helices at the dimerization interface. This is the first reported three-dimensional structure of a member of the ArsR/SmtB family with regulatory metal binding sites at the DNA binding domain and the first structure of a transcription repressor that responds to the heavy metals Cd(II) and Pb(II).

  15. Blubber transcriptome response to acute stress axis activation involves transient changes in adipogenesis and lipolysis in a fasting-adapted marine mammal

    PubMed Central

    Khudyakov, J. I.; Champagne, C. D.; Meneghetti, L. M.; Crocker, D. E.

    2017-01-01

    Stress can compromise an animal’s ability to conserve metabolic stores and participate in energy-demanding activities that are critical for fitness. Understanding how wild animals, especially those already experiencing physiological extremes (e.g. fasting), regulate stress responses is critical for evaluating the impacts of anthropogenic disturbance on physiology and fitness, key challenges for conservation. However, studies of stress in wildlife are often limited to baseline endocrine measurements and few have investigated stress effects in fasting-adapted species. We examined downstream molecular consequences of hypothalamic-pituitary-adrenal (HPA) axis activation by exogenous adrenocorticotropic hormone (ACTH) in blubber of northern elephant seals due to the ease of blubber sampling and its key role in metabolic regulation in marine mammals. We report the first phocid blubber transcriptome produced by RNAseq, containing over 140,000 annotated transcripts, including metabolic and adipocytokine genes of interest. The acute response of blubber to stress axis activation, measured 2 hours after ACTH administration, involved highly specific, transient (lasting <24 hours) induction of gene networks that promote lipolysis and adipogenesis in mammalian adipocytes. Differentially expressed genes included key adipogenesis factors which can be used as blubber-specific markers of acute stress in marine mammals of concern for which sampling of other tissues is not possible. PMID:28186107

  16. Characterization of Zn(II)-responsive ribosomal proteins YkgM and L31 in E. coli.

    PubMed

    Hensley, M Patrick; Gunasekera, Thusitha S; Easton, J Allen; Sigdel, Tara K; Sugarbaker, Stacy A; Klingbeil, Lindsey; Breece, Robert M; Tierney, David L; Crowder, Michael W

    2012-06-01

    RT-PCR and DNA microarrays were used to probe for Zn(II)-responsive genes in E. coli cells that were made Zn(II) deficient. Microarray data revealed 114 genes were significantly up-regulated and 146 genes were significantly down-regulated in Zn(II) deficient conditions. The three most up-regulated genes were (1) znuA, which encodes for a periplasmic protein known to be involved with Zn(II) import, (2) yodA, which encodes for a periplasmic protein with unknown function, and (3) ykgM, which encodes for a ribosomal protein that is thought to be a paralog of ribosomal protein L31. YodA was over-expressed and purified as a maltose binding protein (MBP) fusion protein and shown to tightly bind 4 equivalents of Zn(II). Metal analyses showed that MBP-YkgM does not bind Zn(II). On the other hand, MBP-L31 tightly binds 1 equivalent of Zn(II). EXAFS studies on MBP-L31 suggest a ligand field of 1 histidine, 1 cysteine, and 2 additional N/O scatterers. Site-directed mutagenesis studies suggest that Cys16 coordinates Zn(II) in MBP-L31 and that the other three cysteines do not bind metal. These results are discussed in light of Zn(II) starvation model that has been postulated for B. subtilis.

  17. Salt marsh equilibrium states and transient dynamics in response to changing rates of sea level rise and sediment supply

    NASA Astrophysics Data System (ADS)

    D'Alpaos, A.; Mudd, S. M.; Carniello, L.

    2012-12-01

    Understanding and predicting the response of salt-marsh bio-geomorphic systems to changes in the rate of sea level rise and sediment supply is an issue of paramount importance due to the crucial role exerted by salt marshes within the tidal landscape. Salt-marsh platforms, in fact, buffer coastlines against storms, filter nutrients and pollutants from tidal waters, provide nursery areas for coastal biota, and serve as a sink for organic carbon. Observations of marsh degradation worldwide and the acceleration in the rate of global sea level rise highlight the importance of improving our understanding of the chief processes which control salt-marsh response to current natural climate changes and to the effects of variations in sediment supply. The results of our analytical model of salt-marsh bio-morphodynamic evolution in the vertical plane, accounting for two-way interactions between ecological and geomorphological processes, show that marshes are more resilient to a step decrease in the rate of relative sea level rise rather than to a step increase of the same magnitude. Interestingly, marshes respond more rapidly to an increase in sediment load or vegetation productivity, rather than to a decrease (of the same amount) in sediment load or vegetation productivity. Model results also suggest that marsh stability is positively correlated with tidal range: marshes with high tidal ranges respond more slowly to changes in the environmental forcings and therefore are less likely to be affected by perturbations than their counterparts in low tidal ranges. Finally, the model suggests that, in the case of a oscillating rate of sea level rise, marsh stratigraphy will be unable to fully record short term fluctuations in relative mean sea level, whereas it will be able to capture long term fluctuations particularly in sediment rich, microtidal settings.

  18. Pressor responsiveness to angiotensin II in female mice is enhanced with age: role of the angiotensin type 2 receptor

    PubMed Central

    2014-01-01

    Background The pressor response to angiotensin II (AngII) is attenuated in adult females as compared to males via an angiotensin type 2 receptor (AT2R)-dependent pathway. We hypothesized that adult female mice are protected against AngII-induced hypertension via an enhanced AT2R-mediated pathway and that in reproductively senescent females this pathway is no longer operative. Methods Mean arterial pressure was measured via telemetry in 4-month-old (adult) and 16-month-old (aged) and aged ovariectomized (aged-OVX) wild-type and AT2R knockout (AT2R-KO) female mice during baseline and 14-day infusion of vehicle (saline) or AngII (600 ng/kg/min s.c.). Real-time reverse transcription polymerase chain reaction (RT-PCR) was used to determine renal gene expression of angiotensin receptors and angiotensin-converting enzyme 2 in response to 14-day treatment with vehicle or AngII. Results Basal mean arterial pressure was similar between the groups. The pressor response to AngII was augmented in adult AT2R-KO compared to adult wild-type mice (29 ± 3 mmHg versus 10 ± 4 mmHg, respectively, on day 14 as compared to basal mean arterial pressure, P = 0.002). In wild-type mice, pressor responsiveness to AngII was augmented with age, such that the pressor response to AngII was similar between aged AT2R-KO and wild-type female mice (31 ± 4 mmHg versus 34 ± 3 mmHg, respectively, on day 14, P = 0.9). There were no significant differences in pressor responsiveness to AngII between aged and aged-OVX mice. Vehicle-treated aged wild-type mice had a lower renal AT2R/AT1R balance as compared to adult counterparts. In response to AngII, the renal AT2R/AT1R balance in aged wild-type females was greater than that observed in vehicle-treated aged wild-type females and adult wild-type females, yet the protective effects of AT2R activation were not restored. Conclusions The protective role of the AT2R depressor pathway is lost with age in female mice. Therefore

  19. Differential responses of photosystems I and II to seasonal drought in two Ficus species

    NASA Astrophysics Data System (ADS)

    Zhang, Shubin; Huang, Wei; Zhang, Jiaolin; Cao, Kunfang

    2016-05-01

    Hemiepiphytic Ficus species exhibit more conservative water use strategy and are more drought-tolerant compared with their non-hemiepiphytic congeners, but a difference in the response of photosystem I (PSI) and photosystem II (PSII) to drought stress has not been documented to date. The enhancement of non-photochemical quenching (NPQ) and cyclic electron flow (CEF) have been identified as important mechanisms that protect the photosystems under drought conditions. Using the hemiepiphytic Ficus tinctoria and the non-hemiepiphytic Ficus racemosa, we studied the water status and the electron fluxes through PSI and PSII under seasonal water stress. Our results clearly indicated that the decline in the leaf predawn water potential (ψpd), the maximum photosynthetic rate (Amax) and the predawn maximum quantum yield of PSII (Fv/Fm) were more pronounced in F. racemosa than in F. tinctoria at peak drought. The Fv/Fm of F. racemosa was reduced to 0.69, indicating net photoinhibition of PSII. Concomitantly, the maximal photo-oxidizable P700 (Pm) decreased significantly in F. racemosa but remained stable in F. tinctoria. The fraction of non-photochemical quenching [Y(NPQ)] and the ratio of effective quantum yield of PSI to PSII [Y(I)/Y(II)] increased for both Ficus species at peak drought, with a stronger increase in F. racemosa. These results indicated that the enhancement of NPQ and the activation of CEF contributed to the photoprotection of PSI and PSII for both Ficus species under seasonal drought, particularly for F. racemosa.

  20. Characteristics and control response of the TOPAZ II Reactor System Real-time Dynamic Simulator

    SciTech Connect

    Kwok, K.S.

    1993-11-12

    A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulations of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and casualty conditions.

  1. Platinum(II) Metallomesogens: New External-Stimuli-Responsive Photoluminescence Materials.

    PubMed

    Cuerva, Cristián; Campo, José A; Cano, Mercedes; Lodeiro, Carlos

    2016-07-11

    New dicatenar isoquinoline-functionalized pyrazoles, [Hpz(R(n,n)iq) ] (R(n,n)=C6 H3 (OCn H2n+1 )2 ; n=4, 6, 8, 10, 12, 14, 16, 18), have been strategically designed and synthesized to induce mesomorphic and luminescence properties into the corresponding bis(isoquinolinylpyrazolate)platinum(II) complexes [Pt(pz(R(n,n)iq) )2 ]. Thermal studies reveal that all platinum(II) compounds exhibit columnar mesophases over an exceptionally wide temperature range, above 300 °C in most cases. The photophysical behavior was also investigated in solution and in the solid state. As a consequence of the formation of Pt⋅⋅⋅Pt interactions, the weak greenish emission of the platinum derivatives turns bright orange in the mesophase. Additionally, the complexes are sensitive to a great variety of external inputs, such as temperature, mechanical grinding, pressure, solvents, and vapors. On this basis, they are used as dopant agents of a polyvinylpyrrolidone or poly(methyl methacrylate) polymer matrix to achieve stimuli-responsive thin films.

  2. Workshop on Radio Transients

    NASA Astrophysics Data System (ADS)

    Croft, Steve; Gaensler, Bryan

    2012-04-01

    abstract-type="normal">SummaryWe are entering a new era in the study of variable and transient radio sources. This workshop discussed the instruments and the strategies employed to study those sources, how they are identified and classified, how results from different surveys can be compared, and how radio observations tie in with those at other wavelengths. The emphasis was on learning what common ground there is between the plethora of on-going projects, how methods and code can be shared, and how best practices regarding survey strategy could be adopted. The workshop featured the four topics below. Each topic commenced with a fairly brief introductory talk, which then developed into discussion. By way of preparation, participants had been invited to upload and discuss one slide per topic to a wiki ahead of the workshop. 1. Telescopes, instrumentation and survey strategy. New radio facilities and on-going projects (including upgrades) are both studying the variability of the radio sky, and searching for transients. The discussion first centred on the status of those facilities, and on projects with a time-domain focus, both ongoing and planned, before turning to factors driving choices of instrumentation, such as phased array versus single pixel feeds, the field of view, spatial and time resolution, frequency and bandwidth, depth, area, and cadence of the surveys. 2. Detection, pipelines, and classification. The workshop debated (a) the factors that influence decisions to study variability in the (u,v) plane, in images, or in catalogues, (b) whether, and how much, pipeline code could potentially be shared between one project and another, and which software packages are best for different approaches, (c) how data are stored and later accessed, and (d) how transients and variables are defined and classified. 3. Statistics, interpretation, and synthesis. It then discussed how (i) the choice of facility and strategy and (ii) detection and classification schemes

  3. Light-induced transient ion flux responses from maize leaves and their association with leaf growth and photosynthesis.

    PubMed

    Zivanović, B D; Pang, J; Shabala, S

    2005-03-01

    Net fluxes of H+, K+ and Ca2+ ions from maize (Zea mays L.) isolated leaf segments were measured non-invasively using ion-selective vibrating microelectrodes (the MIFE technique). Leaf segments were isolated from the blade base, containing actively elongating cells (basal segments), and from non-growing tip regions (tip segments). Ion fluxes were measured in response to bright white light (2600 micromoles m-2 s-1) from either the leaf segments or the underlying mesophyll (after stripping the epidermis). Fluxes measured from the mesophyll showed no significant difference between basal and tip regions. In leaf segments (epidermis attached), light-induced flux kinetics of all ions measured (H+, Ca2+ and K+) were strikingly different between the two regions. It appears that epidermal K+ fluxes are required to drive leaf expansion growth, whereas in the mesophyll light-induced K+ flux changes are likely to play a charge balancing role. Light-stimulated Ca2+ influx was not directly attributable either to leaf photosynthetic performance or to leaf expansion growth. It is concluded that light-induced ion flux changes are associated with both leaf growth and photosynthesis.

  4. Individual differences in nicotine dependence, withdrawal symptoms, and sex predict transient fMRI-BOLD responses to smoking cues.

    PubMed

    McClernon, Francis J; Kozink, Rachel V; Rose, Jed E

    2008-08-01

    Exposure to smoking cues increases craving for cigarettes and can precipitate relapse. Whereas brain imaging studies have identified a distinct network of brain regions subserving the processing of smoking cues, little is known about the influence of individual difference factors and withdrawal symptoms on brain cue reactivity. Multiple regression analysis was used to evaluate relations between individual difference factors and withdrawal symptoms and event-related blood oxygen level-dependent responses to visual smoking cues in a sample of 30 smokers. Predictors were self-report nicotine dependence (Fagerström test of nicotine dependence, FTND), prescan withdrawal symptoms (craving and negative affect), and sex. The unique variance of each predictor was examined after controlling for each of the others. Positive associations were observed between FTND and reactivity to cues in right anterior cingulate and orbitofrontal cortex (OFC) whereas negative associations were observed between prescan craving and reactivity in ventral striatum. Higher negative affect or being male was associated with greater reactivity in left hippocampus and left OFC. Women exhibited greater cue reactivity than men in regions including the cuneus and left superior temporal gyrus. Individual difference factors and withdrawal symptoms were uniquely associated with brain reactivity to smoking cues in regions subserving reward, affect, attention, motivation, and memory. These findings provide further evidence that reactivity to conditioned drug cues is multiply determined and suggest that smoking cessation treatments designed to reduce cue reactivity focus on each of these variables.

  5. Thermal and Mechanical Response of TOPAZ II to Pre-Launch and Launch Accidents

    NASA Astrophysics Data System (ADS)

    Eliassi, Mehdi; Mims, James E.

    1994-07-01

    The mechanical and thermal response of Topaz II space nuclear reactor as a result of pre-launch and launch accidents is analyzed. Various accident scenarios such as land and water impact, propellant fires, and propellant explosions are examined. Emphasis is placed on the possibilities of loss of geometry leading to inadvertent criticality and dispersion of fresh fuel and toxic material as a result of these accidents. The preliminary findings indicate that accidental criticality as a result of compaction from land impact and propellant explosion does not appear to be possible. Current analysis shows that solid propellant fires can melt the emitter and might result in fuel ejection. The high melting temperature of uranium dioxide, however, prevents the melting or vaporization of the fresh fuel.

  6. Campbell response in type-II superconductors under strong pinning conditions

    DOE PAGES

    Willa, R.; Geshkenbein, V. B.; Prozorov, R.; ...

    2015-11-11

    Measuring the ac magnetic response of a type II superconductor provides valuable information on the pinning landscape (pinscape) of the material. We use strong pinning theory to derive a microscopic expression for the Campbell length λC, the penetration depth of the ac signal. We show that λC is determined by the jump in the pinning force, in contrast to the critical current jc, which involves the jump in pinning energy. We demonstrate that the Campbell lengths generically differ for zero-field-cooled and field-cooled samples and predict that hysteretic behavior can appear in the latter situation. As a result, we compare ourmore » findings with new experimental data and show the potential of this technique in providing information on the material’s pinscape.« less

  7. Campbell response in type-II superconductors under strong pinning conditions

    SciTech Connect

    Willa, R.; Geshkenbein, V. B.; Prozorov, R.; Blatter, G.

    2015-11-11

    Measuring the ac magnetic response of a type II superconductor provides valuable information on the pinning landscape (pinscape) of the material. We use strong pinning theory to derive a microscopic expression for the Campbell length λC, the penetration depth of the ac signal. We show that λC is determined by the jump in the pinning force, in contrast to the critical current jc, which involves the jump in pinning energy. We demonstrate that the Campbell lengths generically differ for zero-field-cooled and field-cooled samples and predict that hysteretic behavior can appear in the latter situation. As a result, we compare our findings with new experimental data and show the potential of this technique in providing information on the material’s pinscape.

  8. Campbell Response in Type-II Superconductors under Strong Pinning Conditions

    NASA Astrophysics Data System (ADS)

    Willa, R.; Geshkenbein, V. B.; Prozorov, R.; Blatter, G.

    2015-11-01

    Measuring the ac magnetic response of a type II superconductor provides valuable information on the pinning landscape (pinscape) of the material. We use strong pinning theory to derive a microscopic expression for the Campbell length λC , the penetration depth of the ac signal. We show that λC is determined by the jump in the pinning force, in contrast to the critical current jc, which involves the jump in pinning energy. We demonstrate that the Campbell lengths generically differ for zero-field-cooled and field-cooled samples and predict that hysteretic behavior can appear in the latter situation. We compare our findings with new experimental data and show the potential of this technique in providing information on the material's pinscape.

  9. Dynamics of stochastic predator-prey models with Holling II functional response

    NASA Astrophysics Data System (ADS)

    Liu, Qun; Zu, Li; Jiang, Daqing

    2016-08-01

    In this paper, we consider the dynamics of stochastic predator-prey models with Holling II functional response. For the stochastic systems, we firstly establish sufficient conditions for the existence of the globally positive solutions. Then we investigate the asymptotic moment estimations of the positive solutions and study the ultimately bounded in the mean of them. Thirdly, by constructing some suitable Lyapunov functions, we verify that there are unique stationary distributions and they are ergodic. The obtained results show that the systems still retain some stability in the sense of weak stability provided that the intensity of the white noise is relatively small. Finally, some numerical simulations are introduced to illustrate our main results.

  10. Health as Submission and Social Responsibilities: Embodied Experiences of Javanese Women With Type II Diabetes.

    PubMed

    Pitaloka, Dyah; Hsieh, Elaine

    2015-08-01

    By examining women's experiences with type II diabetes, we explore how illness can provide resources to construct meanings of everyday life in Javanese culture. We conducted in-depth interviews with 30 female participants in Central Java, Indonesia, and adopted grounded theory for data analysis. We identified four themes that diabetes serves as resources for women in Indonesia to (a) normalize suffering, (b) resist social control, (c) accept fate, and (d) validate faith. We concluded by noting three unique aspects of Javanese women's illness management. First, through the performance of submission, our participants demonstrated spirituality and religiosity as essential elements of health. Second, diabetes empowers individuals in everyday suffering through two divergent processes: embracing submission and resisting control. Finally, diabetes provides opportunities for individuals within a social network to (re)negotiate social responsibilities. In summary, diabetes provides unique resources to empower our participants to obtain voices that they otherwise would not have had.

  11. Transient absorption study on the influence of several polyphenylene vinylene derivatives on the exciton lifetimes in lead(II) sulfide quantum dots

    NASA Astrophysics Data System (ADS)

    Piatkowski, Piotr; Gadomski, Wojciech; Ratajska-Gadomska, Bozena; Borysiuk, Jolanta

    2012-04-01

    The aim of this Letter is to show the influence of several new polyphenylene vinylene (PPV) derivatives, covering surfaces of lead(II) sulfide semiconductor quantum dots, on optical properties of nanocrystals, especially on exciton lifetimes. The collected data exhibit strong dependence of the excited states lifetimes in PbS nanocrystals on the distance between the polymer chain and the quantum dot. It turns out that the presence of PPV derivatives stabilizes the created exciton, which is manifested by the increase of its lifetime. Anyway this effect weakens in PPV derivatives with longer side chains separating nanocrystal from the main conductive chain.

  12. Electronic and optical response of functionalized Ru(II) complexes: joint theoretical and experimental study

    SciTech Connect

    Kilina, Svetlana; Tretiak, Sergei; Sykora, Milan; Albert, Victor; Badaeva, Ekaterina; Koposov, Alexey

    2008-01-01

    New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the Ru(II) complex to the surface of a semiconductor, a linking bridge -- a carboxyl group -- needs to be added to one or two of the 2,2'-bipyridine (bpy) ligands. Such changes in the ligand structure affect electronic and optical properties and, consequently, the charge transfer reactivity of Ru(II)-systems. In this study, we analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the [Ru(bpy){sub 3}]{sup 2+} complex. First principle calculations based on density functional theory (DFT) and time dependent DFT (TDDFT) are used to simulate the ground and excited-state properties, respectively, of functionalized Ru-complexes in the gas phase and acetonitrile solution. In addition, an effective Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states in all molecules. All theoretical results nicely complement and allow for detailed interpretation of experimental absorption spectra of Ru-complexes that have been done in parallel with our theoretical investigations. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show that deprotonation of the carboxyl group in the Ru-complexes results in a slight blue shift and decrease of oscillator strengths of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotonated complexes demonstrate strong agreement if the theoretical calculations are performed with the addition of a dielectric continuum model. A polar solvent is found to play an

  13. Valley fill in the Andean Eastern Cordillera: a response to transient incision of the Río Iruya, NW Argentina

    NASA Astrophysics Data System (ADS)

    Bovay, C.; Harbor, D. J.; Rahl, J. M.; Staffo, K.; Galli, C.

    2010-12-01

    Headwater valley fill in the Río Iruya chronicles a complex record of deposition and incision at the eastern flank of the Andes. Other intramontane valley fills in NW Argentina have been interpreted to record important dynamics of climate, tectonics, and hillslope failure; specific mechanisms of aggradation include Late Cenozoic climate change, rock uplift and defeat of the channel network, and landslide- or tributary-induced damming. The valley fill is dominated by a horizontally bedded, muddy, coarse-grained, angular conglomerate with few channel cuts, interpreted as gravel-bed, braided river deposits with significant tributary fan volume. The fill contains almost no fine-grained, laminated, or lacustrine deposits, and a general lack of soil horizons in the up to 300 m-thick fill likely indicates continuous deposition. The geometry of preexisting and modern channel network is largely similar. Downstream, the river is actively incising bedrock and has removed most of the fill. In contrast, the headwater reaches contain well-preserved and abundant fill terraces and the river is less commonly eroding bedrock in the valley bottom. The fill becomes mostly eroded downstream of several major tributaries that provided a significant volume of sediment. Ongoing and alternating aggradation and incision are evident in both inset terraces and the modern channel. We consider the applicability of previously established interpretations of valley fill generation. In addition, we evaluate the potential for complex response to base level lowering to cause the aggradation and incision in the Río Iruya. Hypothesized drainage basin reorganization and capture would produce a base level drop, resulting in enormous sediment flux. To estimate the maximum possible erosion rate in the headwaters region, we studied the valley fill sediments using differential GPS. The contact between the fill and the bedrock along the channel was measured to determine the total volume of the fill

  14. Angiotensin II acting on brain AT1 receptors induces adrenaline secretion and pressor responses in the rat.

    PubMed

    Nakamura, Kumiko; Shimizu, Takahiro; Yanagita, Toshihiko; Nemoto, Takayuki; Taniuchi, Keisuke; Shimizu, Shogo; Dimitriadis, Fotios; Yawata, Toshio; Higashi, Youichirou; Ueba, Tetsuya; Saito, Motoaki

    2014-11-28

    Angiotensin II (AngII) plays important roles in the regulation of cardiovascular function. Both peripheral and central actions of AngII are involved in this regulation, but mechanisms of the latter actions as a neurotransmitter/neuromodulator within the brain are still unclear. Here we show that (1) intracerebroventricularly (i.c.v.) administered AngII in urethane-anesthetized male rats elevates plasma adrenaline derived from the adrenal medulla but not noradrenaline with valsartan- (AT1 receptor blocker) sensitive brain mechanisms, (2) peripheral AT1 receptors are not involved in the AngII-induced elevation of plasma adrenaline, although AngII induces both noradrenaline and adrenaline secretion from bovine adrenal medulla cells, and (3) i.c.v. administered AngII elevates blood pressure but not heart rate with the valsartan-sensitive mechanisms. From these results, i.c.v. administered AngII acts on brain AT1 receptors, thereby inducing the secretion of adrenaline and pressor responses. We propose that the central angiotensinergic system can activate central adrenomedullary outflow and modulate blood pressure.

  15. Angiotensin II acting on brain AT1 receptors induces adrenaline secretion and pressor responses in the rat

    PubMed Central

    Nakamura, Kumiko; Shimizu, Takahiro; Yanagita, Toshihiko; Nemoto, Takayuki; Taniuchi, Keisuke; Shimizu, Shogo; Dimitriadis, Fotios; Yawata, Toshio; Higashi, Youichirou; Ueba, Tetsuya; Saito, Motoaki

    2014-01-01

    Angiotensin II (AngII) plays important roles in the regulation of cardiovascular function. Both peripheral and central actions of AngII are involved in this regulation, but mechanisms of the latter actions as a neurotransmitter/neuromodulator within the brain are still unclear. Here we show that (1) intracerebroventricularly (i.c.v.) administered AngII in urethane-anesthetized male rats elevates plasma adrenaline derived from the adrenal medulla but not noradrenaline with valsartan- (AT1 receptor blocker) sensitive brain mechanisms, (2) peripheral AT1 receptors are not involved in the AngII-induced elevation of plasma adrenaline, although AngII induces both noradrenaline and adrenaline secretion from bovine adrenal medulla cells, and (3) i.c.v. administered AngII elevates blood pressure but not heart rate with the valsartan-sensitive mechanisms. From these results, i.c.v. administered AngII acts on brain AT1 receptors, thereby inducing the secretion of adrenaline and pressor responses. We propose that the central angiotensinergic system can activate central adrenomedullary outflow and modulate blood pressure. PMID:25431019

  16. Unique Responses are Observed in Transient Receptor Potential Ankyrin 1 and Vanilloid 1 (TRPA1 and TRPV1) Co-Expressing Cells.

    PubMed

    Sadofsky, Laura R; Sreekrishna, Koti T; Lin, Yakang; Schinaman, Renee; Gorka, Kate; Mantri, Yogita; Haught, John Christian; Huggins, Thomas G; Isfort, Robert J; Bascom, Charles C; Morice, Alyn H

    2014-06-11

    Transient receptor potential (TRP) ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors are implicated in modulation of cough and nociception. In vivo, TRPA1 and TRPV1 are often co-expressed in neurons and TRPA1V1 hetero-tetramer formation is noted in cells co-transfected with the respective expression plasmids. In order to understand the impact of TRP receptor interaction on activity, we created stable cell lines expressing the TRPA1, TRPV1 and co-expressing the TRPA1 and TRPV1 (TRPA1V1) receptors. Among the 600 compounds screened against these receptors, we observed a number of compounds that activated the TRPA1, TRPV1 and TRPA1V1 receptors; compounds that activated TRPA1 and TRPA1V1; compounds that activated TRPV1 and TRPA1V1; compounds in which TRPA1V1 response was modulated by either TRPA1 or TRPV1; and compounds that activated only TRPV1 or TRPA1 or TRPA1V1; and one compound that activated TRPA1 and TRPV1, but not TRPA1V1. These results suggest that co-expression of TRPA1 and TRPV1 receptors imparts unique activation profiles different from that of cells expressing only TRPA1 or TRPV1.

  17. An artificial intelligence system for assisting nuclear power plant operators in the diagnosis of the response to plant faults and transients

    SciTech Connect

    Hajek, B.K.; Stasenko, J.E.; Bhatnagar, R.; Hashemi, S.

    1987-01-01

    An artificial intelligence system is being developed using the Conceptual Structures and Representation Language (CSRL) developed at The Ohio State University Laboratory for Artificial Intelligence Research (LAIR). This system combines three subsystems, which have been independently developed to perform the following tasks: (1) detecting changes in the state of the plant that may lead to conditions requiring operator response and then managing the actions taken by the other two subsystems, (2) diagnosing the plant status independent of alarm states by analyzing the status of basic operating parameters, such as flow rates, pressures, temperatures, and water levels, and providing a determination of the validity of sensor indications, and (3) providing and/or synthesizing an appropriate procedure for the operator to follow to correct the transient of abnormal state of the plant. These three system are tied into the main plant computers, including both the process computer and the safety parameter and display system computer, through the use of a compatible data base. The system is being developed using the Perry Nuclear Power Plant (a BWR/6) as the reference plant, and the General Electric ERIS and GEPAC Plus systems as key data sources. Scenarios are run on by the Perry plant referenced simulator for testing of the artificial intelligence system. Future testing plans call for the system to be interfaced directly to the Perry simulator.

  18. An artificial intelligence system for assisting nuclear power plant operators in the diagnosis of and response to plant faults and transients

    SciTech Connect

    Hajek, B.K.; Stasenko, J.E.; Bhatnagar, R.; Hashemi, S.

    1987-12-01

    This report discusses the Artificial Intelligence (AI) system being developed using the Conceptual Structures and Representation Language (CSRL) developed at the Ohio State University Laboratory for Artificial Intelligence Research (LAIR). This system combines three sub-systems which have been independently developed to perform the tasks of: detecting changes in the state of the plant that may lead to conditions requiring operator response, and then managing the actions taken by the other two subsystems; diagnosing the plant status independent of alarm states by analyzing the status of basic operating parameters such as flow rates, pressures, temperatures, and water levels, and providing a determination of the validity of sensor indications; and providing and/or synthesizing an appropriate procedure for the operator to follow to correct the transient or abnormal state of the plant. These three systems are tied into the main plant computers, including both the process computer and the safety parameter and display system computer, through the use of a compatible database. The architecture of the system is shown in Figure 1. The system is being developed using the Perry Nuclear Power Plant (a BWR/6) as the reference plant, and the General Electric ERIS and GEPAC Plus systems as key data sources. Scenarios are run on the Perry plant referenced simulator for testing of the AI system. Future testing plans call for the system to be interfaced directly to the Perry simulator.

  19. Responses of the summer Asian-Pacific zonal thermal contrast and the associated evolution of atmospheric circulation to transient orbital changes during the Holocene

    NASA Astrophysics Data System (ADS)

    Xiao, Dong; Zhao, Ping; Wang, Yue; Zhou, Xiuji

    2016-10-01

    This study investigates the response of large-scale atmospheric circulation over the Asian-Pacific sector and precipitation over eastern China to transient orbital changes during the Holocene summer using an intermediate-complexity climate model. Corresponding to variations in the incoming solar radiation, the eddy sea level pressure (SLP) exhibited an out-of-phase relationship between the North Pacific and the Eurasian landmass that was similar to the present-day Asia-Pacific Oscillation (APO) pattern and was defined as the paleo-APO. Its index presented an increasing trend, which implies the enhancement of a zonal thermal contrast between Asia and the North Pacific. Associated with the strengthening of the paleo-APO was the westward shift in North Pacific high pressure. Accordingly, there was less/more summer precipitation over both the middle reach of the Yangtze River and Southwest China/over North China. The high-resolution stalagmite δ18O records further support this decrease in the model precipitation. Along with the strengthening of paleo-APO from the early Holocene to the present, the eddy SLP anomalies exhibited a decreasing/increasing trend over the Eurasian landmass/the North Pacific, with a phase change of approximately 4.5 ka BP, and they both moved westward. Meanwhile, a less rainfall belt over eastern China exhibited northward propagation from southern China.

  20. Responses of the summer Asian-Pacific zonal thermal contrast and the associated evolution of atmospheric circulation to transient orbital changes during the Holocene.

    PubMed

    Xiao, Dong; Zhao, Ping; Wang, Yue; Zhou, Xiuji

    2016-10-25

    This study investigates the response of large-scale atmospheric circulation over the Asian-Pacific sector and precipitation over eastern China to transient orbital changes during the Holocene summer using an intermediate-complexity climate model. Corresponding to variations in the incoming solar radiation, the eddy sea level pressure (SLP) exhibited an out-of-phase relationship between the North Pacific and the Eurasian landmass that was similar to the present-day Asia-Pacific Oscillation (APO) pattern and was defined as the paleo-APO. Its index presented an increasing trend, which implies the enhancement of a zonal thermal contrast between Asia and the North Pacific. Associated with the strengthening of the paleo-APO was the westward shift in North Pacific high pressure. Accordingly, there was less/more summer precipitation over both the middle reach of the Yangtze River and Southwest China/over North China. The high-resolution stalagmite δ(18)O records further support this decrease in the model precipitation. Along with the strengthening of paleo-APO from the early Holocene to the present, the eddy SLP anomalies exhibited a decreasing/increasing trend over the Eurasian landmass/the North Pacific, with a phase change of approximately 4.5 ka BP, and they both moved westward. Meanwhile, a less rainfall belt over eastern China exhibited northward propagation from southern China.

  1. Time response of Cd{sub 0.9}Zn{sub 0.1}Te crystals under transient and pulsed irradiation

    SciTech Connect

    Zhao, X. C.; Han, H. T.; Zhang, Z. C.; Ouyang, X. P.; Xu, Y. D.; Wang, T.; Zha, G. Q.; Ouyang, X.

    2012-03-15

    A CdZnTe detector based on high-quality Cd{sub 0.9}Zn{sub 0.1}Te crystals was developed and tested as a monitor in high-intensity radiation fields. The current-voltage measurements were performed using thermally evaporated Au contacts deposited on the crystals, which revealed resistivity of 10{sup 10}{Omega}{center_dot}cm. Typical leakage current for the planar devices was {approx}3 nA for a field strength of 1000 V{center_dot}cm{sup -1}. The test results show that the CdZnTe detector has a fast time response, with a rise time of approximately 2 ns, when exposed to transient and pulsed irradiation of X-rays or electron beams. The decay of current curves is observed and discussed according to charge carrier trapping effects and space-charge accumulation mechanisms. It is suggested that the current decreases quickly with strengthening of the electric field, possibly because of charge de-trapping.

  2. Responses of the summer Asian-Pacific zonal thermal contrast and the associated evolution of atmospheric circulation to transient orbital changes during the Holocene

    PubMed Central

    Xiao, Dong; Zhao, Ping; Wang, Yue; Zhou, Xiuji

    2016-01-01

    This study investigates the response of large-scale atmospheric circulation over the Asian-Pacific sector and precipitation over eastern China to transient orbital changes during the Holocene summer using an intermediate-complexity climate model. Corresponding to variations in the incoming solar radiation, the eddy sea level pressure (SLP) exhibited an out-of-phase relationship between the North Pacific and the Eurasian landmass that was similar to the present-day Asia-Pacific Oscillation (APO) pattern and was defined as the paleo-APO. Its index presented an increasing trend, which implies the enhancement of a zonal thermal contrast between Asia and the North Pacific. Associated with the strengthening of the paleo-APO was the westward shift in North Pacific high pressure. Accordingly, there was less/more summer precipitation over both the middle reach of the Yangtze River and Southwest China/over North China. The high-resolution stalagmite δ18O records further support this decrease in the model precipitation. Along with the strengthening of paleo-APO from the early Holocene to the present, the eddy SLP anomalies exhibited a decreasing/increasing trend over the Eurasian landmass/the North Pacific, with a phase change of approximately 4.5 ka BP, and they both moved westward. Meanwhile, a less rainfall belt over eastern China exhibited northward propagation from southern China. PMID:27779217

  3. Transient Receptor Potential Channel 1 Deficiency Impairs Host Defense and Proinflammatory Responses to Bacterial Infection by Regulating Protein Kinase Cα Signaling

    PubMed Central

    Zhou, Xikun; Ye, Yan; Sun, Yuyang; Li, Xuefeng; Wang, Wenxue; Privratsky, Breanna; Tan, Shirui; Zhou, Zongguang; Huang, Canhua; Wei, Yu-Quan; Birnbaumer, Lutz

    2015-01-01

    Transient receptor potential channel 1 (TRPC1) is a nonselective cation channel that is required for Ca2+ homeostasis necessary for cellular functions. However, whether TRPC1 is involved in infectious disease remains unknown. Here, we report a novel function for TRPC1 in host defense against Gram-negative bacteria. TRPC1−/− mice exhibited decreased survival, severe lung injury, and systemic bacterial dissemination upon infection. Furthermore, silencing of TRPC1 showed decreased Ca2+ entry, reduced proinflammatory cytokines, and lowered bacterial clearance. Importantly, TRPC1 functioned as an endogenous Ca2+ entry channel critical for proinflammatory cytokine production in both alveolar macrophages and epithelial cells. We further identified that bacterium-mediated activation of TRPC1 was dependent on Toll-like receptor 4 (TLR4), which induced endoplasmic reticulum (ER) store depletion. After activation of phospholipase Cγ (PLC-γ), TRPC1 mediated Ca2+ entry and triggered protein kinase Cα (PKCα) activity to facilitate nuclear translocation of NF-κB/Jun N-terminal protein kinase (JNK) and augment the proinflammatory response, leading to tissue damage and eventually mortality. These findings reveal that TRPC1 is required for host defense against bacterial infections through the TLR4-TRPC1-PKCα signaling circuit. PMID:26031335

  4. Psychometric comparison of the PHQ-9 and BDI-II for measuring response during treatment of depression.

    PubMed

    Titov, Nickolai; Dear, Blake F; McMillan, Dean; Anderson, Tracy; Zou, Judy; Sunderland, Matthew

    2011-01-01

    The Patient Health Questionnaire-9 Item (PHQ-9) and Beck Depression Inventory-II (BDI-II) are frequently used measures of depression severity, but little is known about their relative psychometric properties. The authors assessed psychometric properties of both measures during treatment for depression. The PHQ-9 and BDI-II scores from 172 depressed participants in two randomized controlled trials of treatment for depression were assessed and combined. Tests of internal consistency (Cronbach's α), factor analyses, correlational analyses, estimates of clinically significant change, and effect sizes (Cohen's d) were calculated after treatment and follow-up. Both scales demonstrated adequate internal consistency at pre- and posttreatment (PHQ-9 α = .74 and .81; BDI-II α = .87 and .90, respectively). Factor analysis failed to confirm the one-factor model previously reported for the PHQ-9, but two factors evidenced good fit for the BDI-II. Both scales converged more with each other than with the Sheehan Disability Scale at pre- but not at posttreatment. Responsiveness to change of PHQ-9 and BDI-II was similar at both posttreatment and follow-up. The consistency of agreement on indices of clinical significance was fair to moderate, but the BDI-II categorised a greater proportion of participants with severe depression than the PHQ-9. The BDI-II and PHQ-9 demonstrated adequate reliability, convergent/discriminant validity, and similar responsiveness to change. Differences were found in how they categorised severity. Pending the results of further studies, the attributes of the PHQ-9, of being shorter and based on the diagnostic criteria for depression, may indicate an advantage over the BDI-II.

  5. Initiation of a coronal transient

    SciTech Connect

    Low, B.C.; Munro, R.H.; Fisher, R.R.

    1982-03-01

    This paper analyzes the coronal transient/eruptive prominence event of 1980 August 5 observed by the Mauna Loa experiment system. This event yielded data on the early development of the transient in the low corona between 1.2 R/sub sun/ and 2.2 R/sub sun/, information which was not available when earlier attempts were made to explain transient phenomena. The transient's initial appearance in the form of a rising density-depleted structure, prior to the eruption of the associated prominence, can be explained as an effect of magnetic buoyancy. The data indicate that this transient has a density depletion of 17% to 33% relative to an undisturbed corona which is approximately isothermal with a temperature of 1.5 x 10/sup 6/ K and a coronal density of 1.0 x 10/sup 9/ cm/sup -3/ at the base of the corona. The height versus base length relationship of the evolving transient resembles, remarkably well, the theoretical predictions obtained from a quasi-static model of a margnetically buoyant loop system. By matching this relationship with the theoretical model, we estimate the magnetic field at the base of the transient to be between 2 and 3 gauss. It is also shown that the initial, nearly constant speed of the top of the transient, 80 +- 20 km s/sup -1/, is consistent with a theoretical estimate calculated from the quasi-static model. These results suggest that some transients are not initiated impulsively, the initial stage of the development being driven by a quasi-static response to a slow change in magnetic field conditions at the base of the corona.

  6. The chicken vitellogenin II gene is flanked by a GATA factor-dependent estrogen response unit.

    PubMed

    Davis, D L; Burch, J B

    1996-08-01

    The chicken vitellogenin II (VTGII) gene is flanked by an imperfect estrogen response element (ERE) at -350 and a perfect ERE at -620. In the present study we show that this imperfect ERE lies within an estrogen response unit (ERU) that requires a GATA factor and the estrogen receptor to function as an estrogen-dependent enhancer. We infer that GATA-6 contributes to the estrogen-dependent and liver-specific regulation of the endogenous VTGII gene since this is the predominant GATA factor expressed in adult liver. Our analysis of the VTGII ERU revealed four salient points. First, this ERU is comprised of an ERE and a bank of functionally redundant GATA-binding sites. Second, the GATA-6 transactivation domain is necessary (and sufficient, when tethered near the ERE) to render this ERU functional. Third, ERU enhancer activity is dependent on GATA 6, regardless of whether the resident ERE is imperfect or perfect. Fourth, in contrast to a report that the estrogen receptor antagonizes the activity of another GATA factor (GATA-1), we show that these two factors can function in a synergistic manner within the context of the VTGII ERU.

  7. Conceptualization of the predevelopment groundwater flow system and transient water-level responses in Yucca Flat, Nevada National Security Site, Nevada

    USGS Publications Warehouse

    Fenelon, Joseph M.; Sweetkind, Donald S.; Elliott, Peggy E.; Laczniak, Randell J.

    2012-01-01

    aquifer. Flow directions in the alluvial-volcanic aquifer are variable and are controlled by localized areas where small amounts of water can drain into the regional carbonate aquifer. These areas commonly are controlled by geologic structures, such as Yucca fault. Flow in the regional carbonate aquifer generally drains to the center of the basin; from there flow is to the south-southeast out of the study area toward downgradient discharge areas. Southward flow in the regional carbonate aquifer occurs in a prominent potentiometric trough that results from a faulted zone of enhanced permeability centered about Yucca fault. Vertical hydraulic gradients between the aquifer systems are downward throughout the study area; however, flow from the alluvial-volcanic aquifer into the underlying carbonate aquifer is believed to be minor because of the intervening confining unit. Transient water levels were identified and analyzed to understand hydraulic responses to stresses in Yucca Flat. Transient responses have only a minimal influence on the general predevelopment flow directions in the aquifers. The two primary anthropogenic stresses on the groundwater system since about 1950 are nuclear testing and pumping. Most of the potentiometric response in the aquifers to pumping or past nuclear testing is interim and localized. Persistent, long-lasting changes in hydraulic head caused by nuclear testing occur only in confining units where groundwater fluxes are negligible. A third stress on the groundwater system is natural recharge, which can cause minor, short- and long-term changes in water levels. Long-term hydrographs affected by natural recharge, grouped by similar trend, cluster in distinct areas of Yucca Flat and are controlled primarily by spatial differences in local recharge patterns.

  8. Transient increase in squamous cell carcinoma antigen expression in cultured cervical carcinoma CaSki cells in response to exposure to cis-diamminedichloroplatinum.

    PubMed

    Tateiwa, Y; Yoshida, S; Miyahara, Y; Hamana, S; Motoyama, S; Maruo, T

    2003-01-01

    The present study was conducted to elucidate the molecular mechanism underlying the transient increase in circulating squamous cell carcinoma antigen (SCC Ag) levels in response to CIS-diamminedichloroplatinum (CDDP) infusion using an in vitro model. The uterine cervical squamous carcinoma CaSki cells were cultured for 72 h after 3 h exposure to 5.0 microg/ml CDDP. The effects of CDDP exposure on the proliferative activity and apoptosis in cultured CaSki cells were determined by bromodeoxyuridine (BrdU) uptake and cell counting and by the TUNEL assay, respectively. SCC Ag levels in cultured CaSki cells and culture media were determined with the use of SCC-RIA kit. The expression of SCC Ag-1 mRNA and SCC Ag-2 mRNA in cultured CaSki cells was assessed using semiquantitative RT-PCR with Southern blot analysis. The number of BrdU-positive CaSki cells significantly decreased 6 h after exposure to CDDP, whereas the apoptosis-positive rate of cultured CaSki cells significantly increased 12 h after the CDDP exposure. The number of cultured CaSki cells significantly decreased 72 h after the CDDP exposure. The total SCC Ag protein levels in both cultured CaSki cells and the culture media after the 3-hour CDDP exposure increased in a time-dependent manner during the subsequent incubation for 48 h. Semiquantitative RT-PCR revealed that the expression levels of both SCC Ag-1 and SCC Ag-2 mRNA increased (1.7- and 2.7-fold, respectively) 12 h after the exposure to CDDP relative to those before the subsequent cultures. Exposure of uterine cervical squamous carcinoma CaSki cells to CDDP resulted in a transient increase in SCC Ag protein and mRNA expression in those cells during the initial 12 h after the exposure, being associated with decreased proliferative activity and increased apoptosis of those cells.

  9. Adenovirus-mediated brain-derived neurotrophic factor expression regulated by hypoxia response element protects brain from injury of transient middle cerebral artery occlusion in mice.

    PubMed

    Shi, Qindong; Zhang, Pengbo; Zhang, Junfeng; Chen, Xinlin; Lu, Haixia; Tian, Yumei; Parker, T L; Liu, Yong

    2009-11-20

    Some gene expression may be regulated by hypoxia-responsive element (HRE) that is bound by hypoxia-inducible factor-1 (HIF-1) which is up-regulated during cerebral ischemia. To explore ischemia/hypoxia-controlled expression and the neuroprotective effects of brain-derived neurotrophic factor (BDNF) after ischemic brain injury, an adenoviral vector using five copies of hypoxia response element (HRE) in the vascular endothelial growth factor gene to regulate the expression of BDNF gene (Ad5HRE:BDNF) was constructed, and its efficacy was verified for driving BDNF expression in cultured Hela cells under hypoxic condition by ELISA. We found that the concentration of BDNF in the Ad5HRE:BDNF-transfected culture media was 28-fold greater in a hypoxic condition than under normoxia. To examine the effect of Ad5HRE:BDNF on ischemic brain injury in vivo, Ad5HRE:BDNF was injected into right caudate putamen of adult mice 7 days prior to 60 min transient middle cerebral artery occlusion (MCAO). It was found that exogenous BDNF expression was increased in the Ad5HRE-BDNF-treated group and infarct volume of the Ad5HRE:BDNF-treated group at 3 days after MCAO was significantly smaller than that of vehicle- or AdNull-treated groups. Moreover, Ad5HRE:BDNF injection resulted in significantly improved sensorimotor scores 7 days after MCAO and induced a reduction in the number of Fluoro-Jade B-positive neurons and TUNEL-positive cells, compared with vehicle- or AdNull-injection. Our findings suggest that BDNF expression could be regulated in hypoxia/ischemia condition with five copies of HRE and ameliorates ischemic brain injury in a mouse focal cerebral ischemia model.

  10. Potential roles for calcium-sensing receptor (CaSR) and transient receptor potential ankyrin-1 (TRPA1) in murine anorectic response to deoxynivalenol (vomitoxin).

    PubMed

    Wu, Wenda; Zhou, Hui-Ren; Pestka, James J

    2017-01-01

    Food contamination by the trichothecene mycotoxin deoxynivalenol (DON, vomitoxin) has the potential to adversely affect animal and human health by suppressing food intake and impairing growth. In mice, the DON-induced anorectic response results from aberrant satiety hormone secretion by enteroendocrine cells (EECs) of the gastrointestinal tract. Recent in vitro studies in the murine STC-1 EEC model have linked DON-induced satiety hormone secretion to activation of calcium-sensing receptor (CaSR), a G-coupled protein receptor, and transient receptor potential ankyrin-1 (TRPA1), a TRP channel. However, it is unknown whether similar mechanisms mediate DON's anorectic effects in vivo. Here, we tested the hypothesis that DON-induced food refusal and satiety hormone release in the mouse are linked to activation of CaSR and TRPA1. Oral treatment with selective agonists for CaSR (R-568) or TRPA1 (allyl isothiocyanate (AITC)) suppressed food intake in mice, and the agonist's effects were suppressed by pretreatment with corresponding antagonists NPS-2143 or ruthenium red (RR), respectively. Importantly, NPS-2143 or RR inhibited both DON-induced food refusal and plasma elevations of the satiety hormones cholecystokinin (CCK) and peptide YY3-36 (PYY3-36); cotreatment with both antagonists additively suppressed both anorectic and hormone responses to DON. Taken together, these in vivo data along with prior in vitro findings support the contention that activation of CaSR and TRPA1 contributes to DON-induced food refusal by mediating satiety hormone exocytosis from EEC.

  11. Opposing roles for cannabinoid receptor type-1 (CB₁) and transient receptor potential vanilloid type-1 channel (TRPV1) on the modulation of panic-like responses in rats.

    PubMed

    Casarotto, Plínio C; Terzian, Ana Luisa B; Aguiar, Daniele C; Zangrossi, Hélio; Guimarães, Francisco S; Wotjak, Carsten T; Moreira, Fabrício A

    2012-01-01

    The midbrain dorsal periaqueductal gray (dPAG) has an important role in orchestrating anxiety- and panic-related responses. Given the cellular and behavioral evidence suggesting opposite functions for cannabinoid type 1 receptor (CB₁) and transient receptor potential vanilloid type-1 channel (TRPV1), we hypothesized that they could differentially influence panic-like reactions induced by electrical stimulation of the dPAG. Drugs were injected locally and the expression of CB₁ and TRPV1 in this structure was assessed by immunofluorescence and confocal microscopy. The CB₁-selective agonist, ACEA (0.01, 0.05 and 0.5 pmol) increased the threshold for the induction of panic-like responses solely at the intermediary dose, an effect prevented by the CB₁-selective antagonist, AM251 (75 pmol). Panicolytic-like effects of ACEA at the higher dose were unmasked by pre-treatment with the TRPV1 antagonist capsazepine (0.1 nmol). Similarly to ACEA, capsazepine (1 and 10 nmol) raised the threshold for triggering panic-like reactions, an effect mimicked by another TRPV1 antagonist, SB366791 (1 nmol). Remarkably, the effects of both capsazepine and SB366791 were prevented by AM251 (75 pmol). These pharmacological data suggest that a common endogenous agonist may have opposite functions at a given synapse. Supporting this view, we observed that several neurons in the dPAG co-expressed CB₁ and TRPV1. Thus, the present work provides evidence that an endogenous substance, possibly anandamide, may exert both panicolytic and panicogenic effects via its actions at CB₁ receptors and TRPV1 channels, respectively. This tripartite set-point system might be exploited for the pharmacotherapy of panic attacks and anxiety-related disorders.

  12. Implementation of the superfluid helium phase transition using finite element modeling: Simulation of transient heat transfer and He-I/He-II phase front movement in cooling channels of superconducting magnets

    NASA Astrophysics Data System (ADS)

    Bielert, E. R.; Verweij, A. P.; Ten Kate, H. H. J.

    2013-01-01

    In the thermal design of high magnetic field superconducting accelerator magnets, the emphasis is on the use of superfluid helium as a coolant and stabilizing medium. The very high effective thermal conductivity of helium below the lambda transition temperature significantly helps to extract heat from the coil windings during steady state and transient heat deposition. The layout and size of the helium channels have a strong effect on the maximum amount of heat that can be extracted from the porously insulated superconducting cables. To better understand the behavior of superfluid helium penetrating the magnet structure and coil windings, simulation based on a three dimensional finite element model can give valuable insight. The 3D geometries of interest can be regarded as a complex network of coupled 1D geometries. The governing physics is thus similar for both geometries and therefore validation of several and different 1D models is performed. Numerically obtained results and published experimental data are compared. Once the viability of the applied methods is proven, they can be incorporated into the 3D geometries. Not only the transport properties in the bulk of the helium are of interest, but also the strong non-linear behavior at the interfaces between solids and superfluid helium (Kapitza conductance) is important from an engineering point of view, since relatively large temperature jumps may occur here. In this work it is shown how He-II behavior in magnet windings can be simulated using COMSOL Multiphysics. 1D models are validated by experimental results taken from literature in order to improve existing 2D and 3D models with more complete physics. The examples discussed include transient heat transfer in 1D channels, Kapitza conductance and sub-cooling of normal liquid helium to temperatures below the lambda transition in long channels (phase front movement).

  13. Time-domain parameter identification of aeroelastic loads by forced-vibration method for response of flexible structures subject to transient wind

    NASA Astrophysics Data System (ADS)

    Cao, Bochao

    Slender structures representing civil, mechanical and aerospace systems such as long-span bridges, high-rise buildings, stay cables, power-line cables, high light mast poles, crane-booms and aircraft wings could experience vortex-induced and buffeting excitations below their design wind speeds and divergent self-excited oscillations (flutter) beyond a critical wind speed because these are flexible. Traditional linear aerodynamic theories that are routinely applied for their response prediction are not valid in the galloping, or near-flutter regime, where large-amplitude vibrations could occur and during non-stationary and transient wind excitations that occur, for example, during hurricanes, thunderstorms and gust fronts. The linear aerodynamic load formulation for lift, drag and moment are expressed in terms of aerodynamic functions in frequency domain that are valid for straight-line winds which are stationary or weakly-stationary. Application of the frequency domain formulation is restricted from use in the nonlinear and transient domain because these are valid for linear models and stationary wind. The time-domain aerodynamic force formulations are suitable for finite element modeling, feedback-dependent structural control mechanism, fatigue-life prediction, and above all modeling of transient structural behavior during non-stationary wind phenomena. This has motivated the developing of time-domain models of aerodynamic loads that are in parallel to the existing frequency-dependent models. Parameters defining these time-domain models can be now extracted from wind tunnel tests, for example, the Rational Function Coefficients defining the self-excited wind loads can be extracted using section model tests using the free vibration technique. However, the free vibration method has some limitations because it is difficult to apply at high wind speeds, in turbulent wind environment, or on unstable cross sections with negative aerodynamic damping. In the current

  14. Mutant MHC class II epitopes drive therapeutic immune responses to cancer

    PubMed Central

    Kreiter, Sebastian; Vormehr, Mathias; van de Roemer, Niels; Diken, Mustafa; Löwer, Martin; Diekmann, Jan; Boegel, Sebastian; Schrörs, Barbara; Vascotto, Fulvia; Castle, John C.; Tadmor, Arbel D.; Schoenberger, Stephen P.; Huber, Christoph; Türeci, Özlem; Sahin, Ugur

    2016-01-01

    Tumour-specific mutations are ideal targets for cancer immunotherapy as they lack expression in healthy tissues and can potentially be recognized as neo-antigens by the mature T-cell repertoire. Their systematic targeting by vaccine approaches, however, has been hampered by the fact that every patient’s tumour possesses a unique set of mutations (‘the mutanome’) that must first be identified. Recently, we proposed a personalized immunotherapy approach to target the full spectrum of a patient’s individual tumour-specific mutations1. Here we show in three independent murine tumour models that a considerable fraction of non-synonymous cancer mutations is immunogenic and that, unexpectedly, the majority of the immunogenic mutanome is recognized by CD4+ T cells. Vaccination with such CD4+ immunogenic mutations confers strong antitumour activity. Encouraged by these findings, we established a process by which mutations identified by exome sequencing could be selected as vaccine targets solely through bioinformatic prioritization on the basis of their expression levels and major histocompatibility complex (MHC) class II-binding capacity for rapid production as synthetic poly-neo-epitope messenger RNA vaccines. We show that vaccination with such polytope mRNA vaccines induces potent tumour control and complete rejection of established aggressively growing tumours in mice. Moreover, we demonstrate that CD4+ T cell neo-epitope vaccination reshapes the tumour microenvironment and induces cytotoxic T lymphocyte responses against an independent immunodominant antigen in mice, indicating orchestration of antigen spread. Finally, we demonstrate an abundance of mutations predicted to bind to MHC class II in human cancers as well by employing the same predictive algorithm on corresponding human cancer types. Thus, the tailored immunotherapy approach introduced here may be regarded as a universally applicable blueprint for comprehensive exploitation of the substantial neo

  15. Contractile responses to rat urotensin II in resting and depolarized basilar arteries.

    PubMed

    Porras-González, Cristina; Ureña, Juan; Egea-Guerrero, Juan José; Gordillo-Escobar, Elena; Murillo-Cabezas, Francisco; González-Montelongo, María del Carmen; Muñoz-Sánchez, María Angeles

    2014-03-01

    The effects of human urotensin II (hUII) on the vascular tone of different animal species has been studied extensively. However, little has been reported on the vasoactive effects of rat urotensin (rUII) in murine models. The aim of the present study was to investigate the effects of rUII on vasoreactivity in rat basilar arteries. Basilar arteries from adult male Wistar rats (300-350 g) were isolated, cut in rings, and mounted on a small vessel myograph to measure isometric tension. rUII concentrations were studied in both resting and depolarized state. To remove endothelial nitric oxide effects from the rUII response, we treated selected arterial rings with Nω-nitro-L-arginine methyl ester (L-NAME). 10 μM rUII produced a potent vasoconstrictor response in rat basilar arteries with intact endothelium, while isometric forces remained unaffected in arterial rings treated with lower rUII concentrations. Although L-NAME did not have a significant effect on 10 μM rUII-evoked contraction, it slightly increased arterial ring contraction elicited by 1 μM rUII. In depolarized arteries, dose-dependent rUII increased depolarization-induced contractions. This effect was suppressed by L-NAME. Our results show that the rat basilar artery has a vasoconstrictor response to rUII. The most potent vasoconstrictor effect was produced by lower doses of rUII (0.1 and 1 μM) in depolarized arteries with intact endothelium. This effect could facilitate arterial vasospasm in vascular pathophysiological processes such as subarachnoid hemorrhage and hypertension, when sustained depolarization and L-type Ca(2+) channel activation are present.

  16. Drainage effects on the transient, near-surface hydrologic response of a steep hillslope to rainfall: Implications for slope stability, Edmonds, Washington, USA

    USGS Publications Warehouse

    Biavati, G.; Godt, J.W.; McKenna, J.P.

    2006-01-01

    Shallow landslides on steep (>25??) hillsides along Puget Sound have resulted in occasional loss of life and costly damage to property during intense or prolonged rainfall. As part of a larger project to assess landslide hazards in the Seattle area, the U.S. Geological Survey instrumented two coastal bluff sites in 2001 to observe the subsurface hydrologic response to rainfall. The instrumentation at one of these sites, near Edmonds, Washington, consists of two rain gauges, two water-content probes that measure volumetric water content at eight depths between 0.2 and 2.0 m, and two tensiometer nests that measure soil-water suction at six depths ranging from 0.2 to 1.5m. Measurements from these instruments are used to test one- and two-dimensional numerical models of infiltration and groundwater flow. Capillary-rise tests, performed in the laboratory on soil sample from the Edmonds site, are used to define the soil hydraulic properties for the wetting process. The field observations of water content and suction show an apparent effect of porosity variation with depth on the hydraulic response to rainfall. Using a range of physical properties consistent with our laboratory and field measurements, we perform sensitivity analyses to investigate the effects of variation in physical and hydraulic properties of the soil on rainfall infiltration, pore-pressure response, and, hence, slope stability. For a two-layer-system in which the hydraulic conductivity of the upper layer is at least 10 times greater than the conductivity of the lower layer, and the infiltration rate is greater than the conductivity of the lower layer, a perched water table forms above the layer boundary potentially destabilizing the upper layer of soil. Two-dimensional modeling results indicate that the addition of a simple trench drain to the same two-layer slope has differing effects on the hydraulic response depending on the initial pressure head conditions. For slope-parallel flow conditions

  17. Drainage effects on the transient, near-surface hydrologic response of a steep hillslope to rainfall: implications for slope stability, Edmonds, Washington, USA

    NASA Astrophysics Data System (ADS)

    Biavati, G.; Godt, J. W.; McKenna, J. P.

    2006-05-01

    Shallow landslides on steep (>25°) hillsides along Puget Sound have resulted in occasional loss of life and costly damage to property during intense or prolonged rainfall. As part of a larger project to assess landslide hazards in the Seattle area, the U.S. Geological Survey instrumented two coastal bluff sites in 2001 to observe the subsurface hydrologic response to rainfall. The instrumentation at one of these sites, near Edmonds, Washington, consists of two rain gauges, two water-content probes that measure volumetric water content at eight depths between 0.2 and 2.0 m, and two tensiometer nests that measure soil-water suction at six depths ranging from 0.2 to 1.5 m. Measurements from these instruments are used to test one- and two-dimensional numerical models of infiltration and groundwater flow. Capillary-rise tests, performed in the laboratory on soil sample from the Edmonds site, are used to define the soil hydraulic properties for the wetting process. The field observations of water content and suction show an apparent effect of porosity variation with depth on the hydraulic response to rainfall. Using a range of physical properties consistent with our laboratory and field measurements, we perform sensitivity analyses to investigate the effects of variation in physical and hydraulic properties of the soil on rainfall infiltration, pore-pressure response, and, hence, slope stability. For a two-layer-system in which the hydraulic conductivity of the upper layer is at least 10 times greater than the conductivity of the lower layer, and the infiltration rate is greater than the conductivity of the lower layer, a perched water table forms above the layer boundary potentially destabilizing the upper layer of soil. Two-dimensional modeling results indicate that the addition of a simple trench drain to the same two-layer slope has differing effects on the hydraulic response depending on the initial pressure head conditions. For slope-parallel flow conditions

  18. Benchmark Simulations of the Thermal-Hydraulic Responses during EBR-II Inherent Safety Tests using SAM

    SciTech Connect

    Hu, Rui; Sumner, Tyler S.

    2016-01-01

    An advanced system analysis tool SAM is being developed for fast-running, improved-fidelity, and wholeplant transient analyses at Argonne National Laboratory under DOE-NE’s Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. As an important part of code development, companion validation activities are being conducted to ensure the performance and validity of the SAM code. This paper presents the benchmark simulations of two EBR-II tests, SHRT-45R and BOP- 302R, whose data are available through the support of DOE-NE’s Advanced Reactor Technology (ART) program. The code predictions of major primary coolant system parameter are compared with the test results. Additionally, the SAS4A/SASSYS-1 code simulation results are also included for a code-to-code comparison.

  19. Light saturation response of inactive photosystem II reaction centers in spinach.

    PubMed

    Chylla, R A; Whitmarsh, J

    1990-07-01

    The effective absorption cross section of inactive photosystem II (PS II) centers, which is the product of the effective antenna size and the quantum yield for photochemistry, was investigated by comparing the light saturation curves of inactive PS II and active reaction centers in intact chloroplasts and thylakoid membranes of spinach (Spinacia oleracea). Inactive PS II centers are defined as the impaired PS II reaction centers that require greater than 50 ms for the reoxidation of QA (-) subsequent to a single turnover flash. Active reaction centers are defined as the rapidly turning over PS II centers (recovery time less than 50 ms) and all of the PS I centers. The electrochromic shift, measured by the flash-induced absorbance increase at 518 nm, was used to probe the activity of the reaction centers. Light saturation curves were generated for inactive PS II centers and active reaction centers by measuring the extent of the absorbance increase at 518 nm induced by red actinic flashes of variable energy. The light saturation curves show that inactive PS II centers required over twice as many photons as active reaction centers to achieve the same yield. The ratio of the flash energy required for 50% saturation for active reaction centers (PS II active + PS I) compared to inactive PS II centers was 0.45±0.04 in intact chloroplasts, and 0.54±0.11 in thylakoid membranes. Analysis of the light saturation curves using a Poisson statistical model in which the ratio of the antenna size of active PS II centers to that of PS I is considered to range from 1 to 1.5, indicates that the effective absorption cross section of inactive PS II centers was 0.54-0.37 times that of active PS II centers. If the quantum yield for photochemistry is assumed to be one, we estimate that the antenna system serving the inactive PS II centers contains approx. 110 chlorophyll molecules.

  20. Boys II Men: A Culturally-Responsive School Counseling Group for Urban High School Boys of Color

    ERIC Educational Resources Information Center

    Pérez-Gualdrón, Leyla; Yeh, Christine; Russell, LyRyan

    2016-01-01

    Using a participatory and collaborative approach, we developed, implemented, and evaluated a culturally responsive school counseling group, "Boys II Men," for 11 low-income diverse male students of color at an urban public school. The content of the group focused on five areas: social connections and support, exploring gender roles,…

  1. A dilated cardiomyopathy mutation blunts adrenergic response and induces contractile dysfunction under chronic angiotensin II stress.

    PubMed

    Wilkinson, Ross; Song, Weihua; Smoktunowicz, Natalia; Marston, Steven

    2015-12-01

    We investigated cardiac contractility in the ACTC E361G transgenic mouse model of dilated cardiomyopathy (DCM). No differences in cardiac dimensions or systolic function were observed in young mice, whereas young adult mice exhibited only mild diastolic abnormalities. Dobutamine had an inotropic and lusitropic effect on the mouse heart. In papillary muscle at 37°C, dobutamine increased relaxation rates [∼50% increase of peak rate of force decline normalized to force (dF/dtmin/F), 25% reduction of time to 90% relaxation (t90) in nontransgenic (NTG) mice], but in the ACTC E361G mouse, dF/dtmin/F was increased 20-30%, and t90 was only reduced 10% at 10 Hz. Pressure-volume measurements showed increases in maximum rate of pressure decline and decreases in time constant of left ventricular pressure decay in the ACTC E361G mouse that were 25-30% of the changes in the NTG mouse, consistent with blunting of the lusitropic response. The inotropic effect of dobutamine was also blunted in ACTC E361G mice, and the dobutamine-stimulated increase in cardiac output (CO) was reduced from 2,100 to 900 μl/min. Mice were treated with high doses of ANG II for 4 wk. The chronic stress treatment evoked systolic dysfunction in ACTC E361G mice but not in NTG. There was a significant reduction in rates of pressure increase and decrease, as well as reduced end-systolic pressure and increased volume. Ejection fraction and CO were reduced in the ACTC E361G mouse, indicating DCM. In vitro DCM-causing mutations uncouple the relationship between Ca(2+) sensitivity and troponin I phosphorylation. We conclude that this leads to the observed, reduced response to β1 agonists and reduced cardiac reserve that predisposes the heart to DCM under conditions of chronic stress.

  2. Changes in glomerular hemodynamic response to angiotensin II after subacute renal denervation in rats.

    PubMed Central

    Tucker, B J; Mundy, C A; Maciejewski, A R; Printz, M P; Ziegler, M G; Pelayo, J C; Blantz, R C

    1986-01-01

    We examined the changes in glomerular hemodynamics produced by angiotensin II (AII) in both normal Munich-Wistar rats and rats which were unilaterally renal denervated (measured kidney) 4-6 d prior to the measurement periods. Measurements of glomerular dynamics were performed in a control period after plasma volume expansion and during infusion of 11 ng X 100 g body wt-1 X min-1 of AII. The glomerular hydrostatic pressure gradient increased from 38 +/- 1 to 49 +/- 1 mmHg in denervated rats compared with a lesser response in controls (from 39 +/- 1 to 45 +/- 1 mmHg, P less than 0.05). Single nephron plasma flow decreased from 213 +/- 17 to 87 +/- 4 nl X min-1 X g kidney wt (KW)-1 in denervated kidneys versus a more modest decrease in control kidneys (from 161 +/- 9 to 102 +/- 5 nl X min X gKW-1). These changes were due to a greater increase in both afferent and efferent arteriolar resistance after AII infusion in denervated compared with control kidneys. Glomerular AII receptor maximum binding was 1,196 +/- 267 fmol/mg protein in denervated kidneys compared with 612 +/- 89 fmol/mg protein (P less than 0.01) in controls with no change in receptor affinity. We conclude the subacute unilateral renal denervation results in renal vasodilation, denervation magnifies the vasoconstrictive effect of AII infusion on glomerular hemodynamics, and the observed increased response to AII after denervation is associated with increases in glomerular AII receptors. PMID:3745432

  3. Increased hexokinase II expression in the renal glomerulus of mice in response to arsenic

    SciTech Connect

    Pysher, Michele D.; Sollome, James J.; Regan, Suzanne; Cardinal, Trevor R.; Hoying, James B.; Brooks, Heddwen L.; Vaillancourt, Richard R.

    2007-10-01

    Epidemiological studies link arsenic exposure to increased risks of cancers of the skin, kidney, lung, bladder and liver. Additionally, a variety of non-cancerous conditions such as diabetes mellitus, hypertension, and cardiovascular disease have been associated with chronic ingestion of low levels of arsenic. However, the biological and molecular mechanisms by which arsenic exerts its effects remain elusive. Here we report increased renal hexokinase II (HKII) expression in response to arsenic exposure both in vivo and in vitro. In our model, HKII was up-regulated in the renal glomeruli of mice exposed to low levels of arsenic (10 ppb or 50 ppb) via their drinking water for up to 21 days. Additionally, a similar effect was observed in cultured renal mesangial cells exposed to arsenic. This correlation between our in vivo and in vitro data provides further evidence for a direct link between altered renal HKII expression and arsenic exposure. Thus, our data suggest that alterations in renal HKII expression may be involved in arsenic-induced pathological conditions involving the kidney. More importantly, these results were obtained using environmentally relevant arsenic concentrations.

  4. Topoisomerase II Inhibitors Induce DNA Damage-Dependent Interferon Responses Circumventing Ebola Virus Immune Evasion

    PubMed Central

    Luthra, Priya; Aguirre, Sebastian; Yen, Benjamin C.; Pietzsch, Colette A.; Sanchez-Aparicio, Maria T.; Tigabu, Bersabeh; Morlock, Lorraine K.; García-Sastre, Adolfo; Leung, Daisy W.; Williams, Noelle S.; Fernandez-Sesma, Ana; Bukreyev, Alexander

    2017-01-01

    ABSTRACT Ebola virus (EBOV) protein VP35 inhibits production of interferon alpha/beta (IFN) by blocking RIG-I-like receptor signaling pathways, thereby promoting virus replication and pathogenesis. A high-throughput screening assay, developed to identify compounds that either inhibit or bypass VP35 IFN-antagonist function, identified five DNA intercalators as reproducible hits from a library of bioactive compounds. Four, including doxorubicin and daunorubicin, are anthracycline antibiotics that inhibit topoisomerase II and are used clinically as chemotherapeutic drugs. These compounds were demonstrated to induce IFN responses in an ATM kinase-dependent manner and to also trigger the DNA-sensing cGAS-STING pathway of IFN induction. These compounds also suppress EBOV replication in vitro and induce IFN in the presence of IFN-antagonist proteins from multiple negative-sense RNA viruses. These findings provide new insights into signaling pathways activated by important chemotherapy drugs and identify a novel therapeutic approach for IFN induction that may be exploited to inhibit RNA virus replication. PMID:28377530

  5. Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress

    PubMed Central

    Pospíšil, Pavel

    2016-01-01

    The effect of various abiotic stresses on photosynthetic apparatus is inevitably associated with formation of harmful reactive oxygen species (ROS). In this review, recent progress on ROS production by photosystem II (PSII) as a response to high light and high temperature is overviewed. Under high light, ROS production is unavoidably associated with energy transfer and electron transport in PSII. Singlet oxygen is produced by the energy transfer form triplet chlorophyll to molecular oxygen formed by the intersystem crossing from singlet chlorophyll in the PSII antennae complex or the recombination of the charge separated radical pair in the PSII reaction center. Apart to triplet chlorophyll, triplet carbonyl formed by lipid peroxidation transfers energy to molecular oxygen forming singlet oxygen. On the PSII electron acceptor side, electron leakage to molecular oxygen forms superoxide anion radical which dismutes to hydrogen peroxide which is reduced by the non-heme iron to hydroxyl radical. On the PSII electron donor side, incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. Under high temperature, dark production of singlet oxygen results from lipid peroxidation initiated by lipoxygenase, whereas incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. The understanding of molecular basis for ROS production by PSII provides new insight into how plants survive under adverse environmental conditions. PMID:28082998

  6. Probing the many energy-transfer processes in the photosynthetic light-harvesting complex II at 77 K using energy-selective sub-picosecond transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Visser, H. M.; Kleima, F. J.; van Stokkum, I. H. M.; van Grondelle, R.; van Amerongen, H.

    1996-10-01

    The dynamics of energy equilibration in the main plant light-harvesting complex, LHCII, at a temperature of 77 K was probed using sub-picosecond excitation pulses at 649, 661, 672 and 682 nm and detection of the resulting difference absorption spectra from 630 to 700 nm. We find three distinct chlorophyll b to chlorophyll a (Chl a) transfer times, of < 0.3, 0.6 and 4-9 ps, respectively. From a comparison of the amplitudes of the bleaching signal, a plausible scheme for the Chl b to Chl a transfer in the LHCII complex is proposed. Two Chl b molecules transfer energy to Chl a in less than 0.3 ps, two Chl b molecules transfer with 0.6 ps and one Chl b has a transfer time of 4-9 ps. In the Chl a absorption region, a 2.4 ps energy-transfer process from a pigment absorbing around 661 nm, and a 0.4 ps process from a pigment absorbing around 672 nm is found. Furthermore, evidence is found for slow, 10-20 ps energy-transfer processes between some of the Chl a molecules. The data are compared to model calculations using the 3.4 Å LHCII monomer structure (containing 5 Chl b and 7 Chl a molecules) and Förster energy transfer. We conclude that the observed energy-transfer rates are consistent with both the preliminary assignment of the Chl identities ( a or b) of Kühlbrandt et al. and a recent proposal for the arrangement of some of the transition dipole moments (Gülen et al.). Singlet-singlet and singlet-triplet annihilation processes are observed in two different experiments, and both these processes occur with time constants of 2-3 and 12-20 ps, suggesting that both annihilation pathways are at least partly limited by slow energy transfer. The wide range of observed time constants in the equilibration, from < 0.3 to ˜ 20 ps, most likely reflects the irregular arrangement of the pigments in the complex, which shows much less symmetry than the recently obtained structure of the peripheral antenna complex of purple bacteria, LH-II (McDermott et al.).

  7. Foraminifera And Coccolithophorid Assemblage Changes In The Panama Basin During The Last Deglaciation: Response To Sea-Surface Productivity Induced By A Transient Climate Change

    NASA Astrophysics Data System (ADS)

    Martinez, I.; Rincon, D.; Yokoyama, Y.; Barrows, T.

    2004-12-01

    The response of community assemblages of planktonic and benthonic foraminifera and coccolithophorids to transient climate change are explored for the uppermost 2m of cores ODP677B (1.2°N; 83.74°W, 3461m) and TR163-38 (1.34°S; 81.58°W, 2200m), for the last ~40ka. Results suggest that the deglaciation interval was a time of increased productivity and a major reorganization of planktonic trophic webs. The succession in dominance of planktonic foraminifera species Globorotalia inflata, Globigerina bulloides, and Neogloboquadrina pachyderma denote four periods of oceanographic change: (1) advection (24 to 20ka), (2) strong upwelling (20 to 15ka), (3) weak upwelling (14 to 8ka) and (4) oligotrophy (8ka to Present). Strong upwelling for the deglaciation interval is supported by the low Florisphaera profunda / other coccolithophorids ratio and the high percentage abundance of Gephyrocapsa oceanica. Benthonic foraminifera assemblage changes are different in both cores and suggest significant regional variations in surface productivity and/or oxygen content at the seafloor, and a decoupling between surface productivity and export production to the seafloor. This decoupling is evidenced by the inverse relationship between the percentage abundance of infaunal benthonic foraminifera and the percentage abundance of N. pachyderma. The terrigenous input of the Colombian Pacific rivers, particularly the San Juan River, is suggested as a possible mechanism. Finally, the Globorotalia cultrata /Neogloboquadrina dutertrei ratio, is used to reconstruct the past influence of the Costa Rica Dome - Panama Bight and cold tongue upwelling systems in the Panama Basin. A northern influence is suggested for the late Holocene (after 5ka), and the last glacial (before 20ka), whereas a southern influence is suggested for the 20 to 5ka interval. There is a correspondence between our reconstructed northern and southern influences and previously proposed positions of the Intertropical Convergence

  8. Role of protein kinase C (PKC) in short- and long-term cellular responses: inhibition of agonist-mediated calcium transients and down-regulation of PKC

    SciTech Connect

    Fabbro, D.; Mazurek, N.; Borner, C.; Conscience, J.F.; Erne, P.

    1988-01-01

    Active tumor promoters such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or membrane-diffusible synthetic diacylglycerols such as 1,2-dioctanoyl-sn-glycerol (DiC8), which specifically activate protein kinase C (PKC), inhibited the agonist-mediated rise in cytosolic calcium ((Ca2+)i) in a mast cell line (PB-3c) and human platelets. TPA inhibition of agonist-mediated calcium transient in platelets was readily reversed by the PKC inhibitor staurosporine. In contrast to DiCs, only active tumor promoters induced a time- and dose-dependent translocation of cytosolic PKC to membranes as determined both enzymatically or by immunoblotting. However, the concentration of TPA required to induce a half-maximal subcellular redistribution of immunodetectable PKC activity was an order of magnitude greater than the half-maximal dose required to inhibit the intracellular rise in (Ca2+)i. Thus, activation of PKC seems not to be exclusively coupled to its translocation to membranes, suggesting that translocation of PKC is mainly involved in the down-regulation of PKC. Down-regulation of immunoprecipitable PKC was studied in various human breast cancer cell lines that display differential growth inhibitory responses toward the tumor promoter. TPA induced translocation of (35S)methionine-prelabeled cytosolic 80 kDa PKC to membranes followed by complete degradation of the enzyme (t1/2 = 2 h) without affecting PKC synthesis. During prolonged TPA exposure, 20-80% of total 80 kDa PKC of control cells was still synthetized as a membrane-bound 74/80 kDa PKC doublet. Although both proteins lacked PKC activity and phorbol ester binding, they revealed structural similarity with the active 80 kDa PKC form of untreated cells.

  9. Transient Transcriptional Regulation of the CYS-C1 Gene and Cyanide Accumulation upon Pathogen Infection in the Plant Immune Response1[C][W

    PubMed Central

    García, Irene; Rosas, Tábata; Bejarano, Eduardo R.; Gotor, Cecilia; Romero, Luis C.

    2013-01-01

    Cyanide is produced concomitantly with ethylene biosynthesis. Arabidopsis (Arabidopsis thaliana) detoxifies cyanide primarily through the enzyme β-cyanoalanine synthase, mainly by the mitochondrial CYS-C1. CYS-C1 loss of function is not toxic for the plant and leads to an increased level of cyanide in cys-c1 mutants as well as a root hairless phenotype. The classification of genes differentially expressed in cys-c1 and wild-type plants reveals that the high endogenous cyanide content of the cys-c1 mutant is correlated with the biotic stress response. Cyanide accumulation and CYS-C1 gene expression are negatively correlated during compatible and incompatible plant-bacteria interactions. In addition, cys-c1 plants present an increased susceptibility to the necrotrophic fungus Botrytis cinerea and an increased tolerance to the biotrophic Pseudomonas syringae pv tomato DC3000 bacterium and Beet curly top virus. The cys-c1 mutation produces a reduction in respiration rate in leaves, an accumulation of reactive oxygen species, and an induction of the alternative oxidase AOX1a and pathogenesis-related PR1 expression. We hypothesize that cyanide, which is transiently accumulated during avirulent bacterial infection and constitutively accumulated in the cys-c1 mutant, uncouples the respiratory electron chain dependent on the cytochrome c oxidase, and this uncoupling induces the alternative oxidase activity and the accumulation of reactive oxygen species, which act by stimulating the salicylic acid-dependent signaling pathway of the plant immune system. PMID:23784464

  10. Activation of store-mediated calcium entry by secretion-like coupling between the inositol 1,4,5-trisphosphate receptor type II and human transient receptor potential (hTrp1) channels in human platelets.

    PubMed Central

    Rosado, J A; Sage, S O

    2001-01-01

    Physical coupling between inositol 1,4,5-trisphosphate (IP(3)) receptors and transient receptor potential (Trp) channels has been demonstrated in both transfected and normal cells as a candidate mechanism for the activation of store-mediated Ca(2+) entry (SMCE). We have investigated the properties of the coupling between the type II IP(3) receptor and naturally expressed human Trp1 (hTrp1) in human platelets. Treatment with xestospongin C, an inhibitor of IP(3) receptor function, abolished SMCE and coupling between the IP(3) receptor and hTrp1. The coupling was activated by depletion of the intracellular Ca(2+) stores, and was reversed by refilling of the stores. We have also examined the role of actin filaments in the activation and maintenance of the coupling. Stabilization of the cortical actin network with jasplakinolide prevented the coupling, indicating that, as with secretion, the actin filaments at the cell periphery act as a negative clamp which prevents constitutive coupling. In addition, the actin cytoskeleton plays a positive role, since disruption of the actin network inhibited the coupling when the Ca(2+) stores were depleted. These results provide strong evidence for the activation of SMCE by a secretion-like coupling mechanism involving a reversible association between IP(3) receptors and hTrp1 in normal human cells. PMID:11336651

  11. Off-normal performance of EBR-II (Experimental Breeder Reactor) driver fuel

    SciTech Connect

    Seidel, B.R.; Batte, G.L.; Lahm, C.E.; Fryer, R.M.; Koenig, J.F.; Hofman, G.L.

    1986-09-01

    The off-normal performance of EBR-II Mark-II driver fuel has been more than satisfactory as demonstrated by robust reliability under repeated transient overpower and undercooled loss-of-flow tests, by benign run-beyond-cladding-breach behavior, and by forgiving response to fabrication defects including lack of bond. Test results have verified that the metallic driver fuel is very tolerant of off-normal events. This behavior has allowed EBR-II to operate in a combined steady-state and transient mode to provide test capability without limitation from the metallic driver fuel.

  12. HDAC6 contributes to pathological responses of heart and skeletal muscle to chronic angiotensin-II signaling

    PubMed Central

    Demos-Davies, Kimberly M.; Ferguson, Bradley S.; Cavasin, Maria A.; Mahaffey, Jennifer H.; Williams, Sarah M.; Spiltoir, Jessica I.; Schuetze, Katherine B.; Horn, Todd R.; Chen, Bo; Ferrara, Claudia; Scellini, Beatrice; Piroddi, Nicoletta; Tesi, Chiara; Poggesi, Corrado; Jeong, Mark Y.

    2014-01-01

    Little is known about the function of the cytoplasmic histone deacetylase HDAC6 in striated muscle. Here, we addressed the role of HDAC6 in cardiac and skeletal muscle remodeling induced by the peptide hormone angiotensin II (ANG II), which plays a central role in blood pressure control, heart failure, and associated skeletal muscle wasting. Comparable with wild-type (WT) mice, HDAC6 null mice developed cardiac hypertrophy and fibrosis in response to ANG II. However, whereas WT mice developed systolic dysfunction upon treatment with ANG II, cardiac function was maintained in HDAC6 null mice treated with ANG II for up to 8 wk. The cardioprotective effect of HDAC6 deletion was mimicked in WT mice treated with the small molecule HDAC6 inhibitor tubastatin A. HDAC6 null mice also exhibited improved left ventricular function in the setting of pressure overload mediated by transverse aortic constriction. HDAC6 inhibition appeared to preserve systolic function, in part, by enhancing cooperativity of myofibrillar force generation. Finally, we show that HDAC6 null mice are resistant to skeletal muscle wasting mediated by chronic ANG-II signaling. These findings define novel roles for HDAC6 in striated muscle and suggest potential for HDAC6-selective inhibitors for the treatment of cardiac dysfunction and muscle wasting in patients with heart failure. PMID:24858848

  13. Transient Shifts of Incubation Temperature Reveal Immediate and Long-Term Transcriptional Response in Chicken Breast Muscle Underpinning Resilience and Phenotypic Plasticity

    PubMed Central

    Naraballobh, Watcharapong; Trakooljul, Nares; Murani, Eduard; Brunner, Ronald; Krischek, Carsten; Janisch, Sabine; Ponsuksili, Siriluck

    2016-01-01

    Variations in egg incubation temperatures can have acute or long-term effects on gene transcription in avian species. Altered gene expression may, in turn, affect muscle traits in poultry and indirectly influence commercial production. To determine how changes in eggshell temperature affect gene expression, incubation temperatures were varied [36.8°C (low), 37.8°C (control), 38.8°C (high)] at specific time periods reflecting two stages of myogenesis [embryonic days (ED) 7–10 and 10–13]. Gene expression was compared between interventions and matching controls by microarrays in broiler breast muscle at ED10 or ED13 and post-hatch at day 35. Early (ED7-10) high incubation temperature (H10ΔC) resulted in 1370 differentially expressed genes (DEGs) in embryos. Ingenuity pathway analysis revealed temporary activation of cell maintenance, organismal development, and survival ability genes, but these effects were not maintained in adults. Late high incubation temperature (ED10-13) (H13ΔC) had slightly negative impacts on development of cellular components in embryos, but a cumulative effect was observed in adults, in which tissue development and nutrition metabolism were affected. Early low incubation temperature (L10ΔC) produced 368 DEGs, most of which were down-regulated and involved in differentiation and formation of muscle cells. In adults, this treatment down-regulated pathways of transcriptional processes, but up-regulated cell proliferation. Late low temperature incubation (L13ΔC) produced 795 DEGs in embryos, and activated organismal survival and post-transcriptional regulation pathways. In adults this treatment activated cellular and organ development, nutrition and small molecule activity, and survival rate, but deactivated size of body and muscle cells. Thermal interventions during incubation initiate immediate and delayed transcriptional responses that are specific for timing and direction of treatment. Interestingly, the transcriptional response to

  14. Angiotensin II regulates brain (pro)renin receptor expression through activation of cAMP response element-binding protein.

    PubMed

    Li, Wencheng; Liu, Jiao; Hammond, Sean L; Tjalkens, Ronald B; Saifudeen, Zubaida; Feng, Yumei

    2015-07-15

    We reported that brain (pro)renin receptor (PRR) expression levels are elevated in DOCA-salt-induced hypertension; however, the underlying mechanism remained unknown. To address whether ANG II type 1 receptor (AT1R) signaling is involved in this regulation, we implanted a DOCA pellet and supplied 0.9% saline as the drinking solution to C57BL/6J mice. Sham pellet-implanted mice that were provided regular drinking water served as controls. Concurrently, mice were intracerebroventricularly infused with the AT1R blocker losartan, angiotensin-converting-enzyme inhibitor captopril, or artificial cerebrospinal fluid for 3 wk. Intracerebroventricular infusion of losartan or captopril attenuated DOCA-salt-induced PRR mRNA elevation in the paraventricular nucleus of the hypothalamus, suggesting a role for ANG II/AT1R signaling in regulating PRR expression during DOCA-salt hypertension. To test which ANG II/AT1R downstream transcription factors were involved in PRR regulation, we treated Neuro-2A cells with ANG II with or without CREB (cAMP response element-binding protein) or AP-1 (activator protein-1) inhibitors, or CREB siRNA. CREB and AP-1 inhibitors, as well as CREB knockdown abolished ANG II-induced increases in PRR levels. ANG II also induced PRR upregulation in primary cultured neurons. Chromatin immunoprecipitation assays revealed that ANG II treatment increased CREB binding to the endogenous PRR promoter in both cultured neurons and hypothalamic tissues of DOCA-salt hypertensive mice. This increase in CREB activity was reversed by AT1R blockade. Collectively, these findings indicate that ANG II acts via AT1R to upregulate PRR expression both in cultured cells and in DOCA-salt hypertensive mice by increasing CREB binding to the PRR promoter.

  15. Nuclei-mode particulate emissions and their response to fuel sulfur content and primary dilution during transient operations of old and modern diesel engines.

    PubMed

    Liu, Z Gerald; Vasys, Victoria N; Kittelson, David B

    2007-09-15

    The effects of fuel sulfur content and primary dilution on PM number emissions were investigated during transient operations of an old and a modern diesel engine. Emissions were also studied during steady-state operations in order to confirm consistency with previous findings. Testing methods were concurrent with those implemented by the EPA to regulate PM mass emissions, including the use of the Federal Transient Testing Procedure-Heavy Duty cycle to simulate transient conditions and the use of a Critical Flow Venturi-Constant Volume System to provide primary dilution. Steady-state results were found to be consistent with previous studies in that nuclei-mode particulate emissions were largely reduced when lower-sulfur content fuel was used in the newer engine, while the nuclei-mode PM emissions from the older engine were much less affected by fuel sulfur content. The transient results, however, show that the total number of nuclei-mode PM emissions from both engines increases with fuel sulfur content, although this effect is only seen under the higher primary dilution ratios with the older engine. Transient results further show that higher primary dilution ratios increase total nuclei-mode PM number emissions in both engines.

  16. Transient thermoregulatory model with graphics output

    NASA Technical Reports Server (NTRS)

    Grounds, D. J.

    1974-01-01

    A user's guide is presented for the transient version of the thermoregulatory model. The model is designed to simulate the transient response of the human thermoregulatory system to thermal inputs. The model consists of 41 compartments over which the terms of the heat balance are computed. The control mechanisms which are identified are sweating, vaso-constriction and vasodilation.

  17. Transient effects in Herschel/PACS spectroscopy

    NASA Astrophysics Data System (ADS)

    Fadda, Dario; Jacobson, Jeffery D.; Appleton, Philip N.

    2016-10-01

    Context. The Ge:Ga detectors used in the PACS spectrograph onboard the Herschel space telescope react to changes of the incident flux with a certain delay. This generates transient effects on the resulting signal which can be important and last for up to an hour. Aims: The paper presents a study of the effects of transients on the detected signal and proposes methods to mitigate them especially in the case of the unchopped mode. Methods: Since transients can arise from a variety of causes, we classified them in three main categories: transients caused by sudden variations of the continuum due to the observational mode used; transients caused by cosmic ray impacts on the detectors; transients caused by a continuous smooth variation of the continuum during a wavelength scan. We propose a method to disentangle these effects and treat them separately. In particular, we show that a linear combination of three exponential functions is needed to fit the response variation of the detectors during a transient. An algorithm to detect, fit, and correct transient effects is presented. Results: The solution proposed to correct the signal for the effects of transients substantially improves the quality of the final reduction with respect to the standard methods used for archival reduction in the cases where transient effects are most pronounced. Conclusions: The programs developed to implement the corrections are offered through two new interactive data reduction pipelines in the latest releases of the Herschel Interactive Processing Environment.

  18. Phase I to II cross-induction of xenobiotic metabolizing enzymes: A feedforward control mechanism for potential hormetic responses

    SciTech Connect

    Zhang Qiang Pi Jingbo; Woods, Courtney G.; Andersen, Melvin E.

    2009-06-15

    Hormetic responses to xenobiotic exposure likely occur as a result of overcompensation by the homeostatic control systems operating in biological organisms. However, the mechanisms underlying overcompensation that leads to hormesis are still unclear. A well-known homeostatic circuit in the cell is the gene induction network comprising phase I, II and III metabolizing enzymes, which are responsible for xenobiotic detoxification, and in many cases, bioactivation. By formulating a differential equation-based computational model, we investigated in this study whether hormesis can arise from the operation of this gene/enzyme network. The model consists of two feedback and one feedforward controls. With the phase I negative feedback control, xenobiotic X activates nuclear receptors to induce cytochrome P450 enzyme, which bioactivates X into a reactive metabolite X'. With the phase II negative feedback control, X' activates transcription factor Nrf2 to induce phase II enzymes such as glutathione S-transferase and glutamate cysteine ligase, etc., which participate in a set of reactions that lead to the metabolism of X' into a less toxic conjugate X''. The feedforward control involves phase I to II cross-induction, in which the parent chemical X can also induce phase II enzymes directly through the nuclear receptor and indirectly through transcriptionally upregulating Nrf2. As a result of the active feedforward control, a steady-state hormetic relationship readily arises between the concentrations of the reactive metabolite X' and the extracellular parent chemical X to which the cell is exposed. The shape of dose-response evolves over time from initially monotonically increasing to J-shaped at the final steady state-a temporal sequence consistent with adaptation-mediated hormesis. The magnitude of the hormetic response is enhanced by increases in the feedforward gain, but attenuated by increases in the bioactivation or phase II feedback loop gains. Our study suggests a

  19. Responses of slowly adapting type II afferent fibres in cat hairy skin to vibrotactile stimuli.

    PubMed Central

    Gynther, B D; Vickery, R M; Rowe, M J

    1992-01-01

    1. Slowly adapting type II (SAII) afferent fibres that supply the forelimb were isolated from the medial cutaneous nerve of anaesthetized cats and examined for their capacity to signal information about vibrotactile events in the hairy skin. 2. The SAII fibres had a single spot-like receptive field focus where they were highly sensitive to steady indentation and vibration applied with probes normal to the skin surface. However, their sensitivity was affected profoundly by the size of the stimulus probe, its position in relation to the receptive field focus and, to a lesser extent, the magnitude of any pre-indentation on which vibration was superimposed. Small stimulus probes (e.g. 250 microns diameter) were much more effective than larger (> or = 1-2 mm) ones, and small shifts in the position of the perpendicularly applied probe away from the receptive field focus led to a marked decline in responsiveness. 3. With appropriate choice of stimulus parameters for vibratory stimuli applied at the receptive field focus, the SAII fibres could respond at low threshold (< 100 microns), with a tightly phase-locked, regular 1:1 impulse pattern (one impulse per vibration cycle) that accurately signalled the vibration frequency over a bandwidth that extended to 600 Hz. Furthermore, their responses remained phase-locked up to 1000 Hz. Phase-locking in SAII fibres was marginally tighter than that in SAI fibres and comparable to that of Pacinian corpuscle fibres. 4. The sensitivity of forelimb SAII fibres to tangential skin stretch was directionally selective; stretch across the forelimb was much more effective than along its long axis. Vibration associated with tangential skin stretch led to a marked spatial expansion of the field of vibration sensitivity. SAII fibres could therefore signal information about natural stimuli that contain elements of skin stretch and vibration, as may be encountered when the forelimb brushes against textured surfaces. Should the SAII fibres fail to

  20. p47(phox) is required for afferent arteriolar contractile responses to angiotensin II and perfusion pressure in mice.

    PubMed

    Lai, En Yin; Solis, Glenn; Luo, Zaiming; Carlstrom, Mattias; Sandberg, Kathryn; Holland, Steven; Wellstein, Anton; Welch, William J; Wilcox, Christopher S

    2012-02-01

    Myogenic and angiotensin contractions of afferent arterioles generate reactive oxygen species. Resistance vessels express neutrophil oxidase-2 and -4. Angiotensin II activates p47(phox)/neutrophil oxidase-2, whereas it downregulates NOX-4. Therefore, we tested the hypothesis that p47(phox) enhances afferent arteriolar angiotensin contractions. Angiotensin II infusion in p47(phox) +/+ but not -/- mice increased renal cortical NADPH oxidase activity (7±1-12±1 [P<0.01] versus 5±1-7±1 10(3) · RLU · min(-1) · μg protein(-1) [P value not significant]), mean arterial pressure (77±2-91±2 [P<0.005] versus 74±2-77±1 mm Hg [P value not significant]), and renal vascular resistance (7.5±0.4-10.1±0.7 [P<0.01] versus 7.9±0.4-8.3±0.4 mm Hg/mL · min(-1) · gram kidney weight(-1) [P value not significant]). Afferent arterioles from p47(phox) -/- mice had a lesser myogenic response (3.1±0.4 versus 1.4±0.2 dynes · cm(-1) · mm Hg(-1); P<0.02) and a lesser (P<0.05) contraction to 10(-6) M angiotensin II (diameter change +/+: 9.3±0.2-3.4±0.6 μm versus -/-: 9.9±0.6-7.5±0.4 μm). Angiotensin and increased perfusion pressure generated significantly (P<0.05) more reactive oxygen species in p47(phox) +/+ than -/- arterioles. Angiotensin II infusion increased the maximum responsiveness of afferent arterioles from p47(phox) +/+ mice to 10(-6) M angiotensin II yet decreased the response in p47(phox) -/- mice. The angiotensin infusion increased the sensitivity to angiotensin II only in p47(phox) +/+ mice. We conclude that p47(phox) is required to enhance renal NADPH oxidase activity and basal afferent arteriolar myogenic and angiotensin II contractions and to switch afferent arteriolar tachyphylaxis to sensitization to angiotensin during a prolonged angiotensin infusion. These effects likely contribute to hypertension and renal vasoconstriction during infusion of angiotensin II.

  1. The Rapid Transient Surveyor

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Tonry, John; Wright, Shelley; Tully, R. Brent; Lu, Jessica R.; Takamiya, Marianne Y.; Hunter, Lisa

    2016-01-01

    The next decade of astronomy will be dominated by large area surveys (see the detailed discussion in the Astro-2010 Decadal survey and NRC's recent OIR System Report). Ground-based optical transient surveys, e.g., LSST, ZTF and ATLAS and space-based exoplanet, supernova, and lensing surveys such as TESS and WFIRST will join the Gaia all-sky astrometric survey in producing a flood of data that will enable leaps in our understanding of the universe. There is a critical need for further characterization of these discoveries through high angular resolution images, deeper images, spectra, or observations at different cadences or periods than the main surveys. Such follow-up characterization must be well matched to the particular surveys, and requires sufficient additional observing resources and time to cover the extensive number of targets.We describe plans for the Rapid Transient Surveyor (RTS), a permanently mounted, rapid-response, high-cadence facility for follow-up characterization of transient objects on the U. of Hawai'i 2.2-m telescope on Maunakea. RTS will comprise an improved robotic laser adaptive optics system, based on the prototype Robo-AO system (formerly at the Palomar 1.5-m and now at the Kitt Peak 2.2-m telescope), with simultaneous visible and near-infrared imagers as well as a near-infrared integral field spectrograph (R~100, λ = 850 - 1830 nm, 0.15″ spaxels, 8.7″×6.0″ FoV). RTS will achieve an acuity of ~0.07″ in visible wavelengths and < 0.16″ in the near infrared leading to an increase of the infrared point-source sensitivity against the sky background by a factor of ~9, crucial for efficient near-infrared spectroscopy.RTS will allow us to map the dark matter distribution in the z < 0.1 local universe with ten times better accuracy and precision than previous experiments. ATLAS will discover several thousand SNIae per year, measuring SNIa peak brightness, and decline rates, while RTS will measure reddening by dust, confirm SN type and

  2. Transient tachypnea - newborn

    MedlinePlus

    TTN; Wet lungs - newborns; Retained fetal lung fluid; Transient RDS; Prolonged transition; Neonatal - transient tachypnea ... As the baby grows in the womb, the lungs make a special fluid. This fluid fills the ...

  3. Type II pneumocytes modulate surfactant production in response to cigarette smoke constituents: restoration by vitamins A and E.

    PubMed

    Xue, Yuan; Williams, Tracy L; Li, Ting; Umbehr, Joshua; Fang, Liang; Wang, Weiqun; Baybutt, Richard C

    2005-12-01

    This study was to evaluate the effects of cigarette smoke constituents upon type II pneumocyte surfactant production in vitro, and how vitamins A and E may alter the response. Freshly isolated type II pneumocytes from Sprague-Dawley rats were incubated 20 h in medium with fetal bovine serum that was or was not treated with cigarette smoke. The number of adherent cells was inversely related to the dose of smoke or benzo(a)pyrene. Despite the decreased number of treated cells, the total amount of surfactant per culture well was unchanged, whereas surfactant production per cell was significantly increased (P<0.05). Vitamin A concentration was significantly (P<0.05) lower in the smoke-treated serum compared with untreated serum. When vitamin A or E was added to the cigarette smoke-treated serum, cell adherence and surfactant production returned to control values. In conclusion, cigarette smoke constituents or benzo(a)pyrene alone decreased the number of adherent type II pneumocytes, but did not alter surfactant amounts because of an increased production of surfactant per cell. Type II pneumocytes seem to adjust surfactant production dependent upon the number of type II pneumocytes to produce it and vitamin A or E enhance cell attachment in the presence of the smoke toxins.

  4. Transient drainage summary report

    SciTech Connect

    1996-09-01

    This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage.

  5. A nonhuman primate toxicology and immunogenicity study evaluating aerosol delivery of AERAS-402/Ad35 vaccine: Evidence for transient t cell responses in peripheral blood and robust sustained responses in the lungs.

    PubMed

    Hokey, David A; Wachholder, Robert; Darrah, Patricia A; Bolton, Diane L; Barouch, Dan H; Hill, Krystal; Dheenadhayalan, Veerabadran; Schwander, Stephan; Godin, C Steven; Douoguih, Macaya; Pau, Maria Grazia; Seder, Robert A; Roederer, Mario; Sadoff, Jerald C; Sizemore, Donata

    2014-01-01

    Bacille Calmette-Guérin (BCG), the only licensed vaccine for the prevention of tuberculosis (TB), provides only limited protection against certain forms of Mycobacterium tuberculosis (Mtb) infection. While infection with Mtb can be treated with antibiotics, the therapy is expensive, toxic, and requires several months for treatment. In addition, the emergence of drug resistant strains limits the impact of antibiotics and underlines the importance of developing a more effective vaccine to control this disease. Given that pulmonary TB is the most common form of the disease, a vaccine capable of inducing lung-resident immunity may be advantageous for combating this infection. New advances in pulmonary delivery make this route of vaccination feasible and affordable. Here, we evaluate the safety and immunogenicity of an aerosolized Ad35-based vaccine, AERAS-402, delivered to the lungs in nonhuman primates as part of a GLP acute and chronic toxicology and safety study. In this study, animals received three high doses (1 x 10(11) vp) of AERAS-402 by inhalation via a nebulizer at 1-week intervals. Aerosol delivery of AERAS-402 resulted in an increase in relative lung weights as well as microscopic findings in the lungs, mediastinal lymph nodes, bronchus-associated lymphatic tissue, and the naso-oropharynx that were consistent with the induction of an immune response during the acute phase. These findings resolved by the chronic phase and were considered to be non-adverse. Furthermore, we observed transient vaccine-specific immune responses in the peripheral blood as well as sustained high-level polyfunctional CD4(+) and CD8(+) T cell responses in the bronchoalveolar lavage fluid of vaccinated nonhuman primates. The data suggest that pulmonary delivery of Ad35-based vaccines can be safe and can induce potent lung-resident immunity.

  6. Transient catalytic combustor model

    NASA Technical Reports Server (NTRS)

    Tien, J. S.

    1981-01-01

    A quasi-steady gas phase and thermally thin substrate model is used to analyze the transient behavior of catalytic monolith combustors in fuel lean operation. The combustor response delay is due to the substrate thermal inertia. Fast response is favored by thin substrate, short catalytic bed length, high combustor inlet and final temperatures, and small gas channel diameters. The calculated gas and substrate temperature time history at different axial positions provides an understanding of how the catalytic combustor responds to an upstream condition change. The computed results also suggest that the gas residence times in the catalytic bed in the after bed space are correlatable with the nondimensional combustor response time. The model also performs steady state combustion calculations; and the computed steady state emission characteristics show agreement with available experimental data in the range of parameters covered. A catalytic combustor design for automotive gas turbine engine which has reasonably fast response ( 1 second) and can satisfy the emission goals in an acceptable total combustor length is possible.

  7. Transient catalytic combustor model

    NASA Astrophysics Data System (ADS)

    Tien, J. S.

    1981-05-01

    A quasi-steady gas phase and thermally thin substrate model is used to analyze the transient behavior of catalytic monolith combustors in fuel lean operation. The combustor response delay is due to the substrate thermal inertia. Fast response is favored by thin substrate, short catalytic bed length, high combustor inlet and final temperatures, and small gas channel diameters. The calculated gas and substrate temperature time history at different axial positions provides an understanding of how the catalytic combustor responds to an upstream condition change. The computed results also suggest that the gas residence times in the catalytic bed in the after bed space are correlatable with the nondimensional combustor response time. The model also performs steady state combustion calculations; and the computed steady state emission characteristics show agreement with available experimental data in the range of parameters covered. A catalytic combustor design for automotive gas turbine engine which has reasonably fast response ( 1 second) and can satisfy the emission goals in an acceptable total combustor length is possible.

  8. A computer simulation of the transient response of a 4 cylinder Stirling engine with burner and air preheater in a vehicle

    NASA Technical Reports Server (NTRS)

    Martini, W. R.

    1981-01-01

    A series of computer programs are presented with full documentation which simulate the transient behavior of a modern 4 cylinder Siemens arrangement Stirling engine with burner and air preheater. Cold start, cranking, idling, acceleration through 3 gear changes and steady speed operation are simulated. Sample results and complete operating instructions are given. A full source code listing of all programs are included.

  9. Structural response of phyllomanganates to wet aging and aqueous Mn(II)

    NASA Astrophysics Data System (ADS)

    Hinkle, Margaret A. G.; Flynn, Elaine D.; Catalano, Jeffrey G.

    2016-11-01

    Naturally occurring Mn(IV/III) oxides are often formed through microbial Mn(II) oxidation, resulting in reactive phyllomanganates with varying Mn(IV), Mn(III), and vacancy contents. Residual aqueous Mn(II) may adsorb in the interlayer of phyllomanganates above vacancies in their octahedral sheets. The potential for interlayer Mn(II)-layer Mn(IV) comproportionation reactions and subsequent formation of structural Mn(III) suggests that aqueous Mn(II) may cause phyllomanganate structural changes that alters mineral reactivity or trace metal scavenging. Here we examine the effects of aging phyllomanganates with varying initial vacancy and Mn(III) content in the presence and absence of dissolved Mn(II) at pH 4 and 7. Three phyllomanganates were studied: two exhibiting turbostratic layer stacking (δ-MnO2 with high vacancy content and hexagonal birnessite with both vacancies and Mn(III) substitutions) and one with rotationally ordered layer stacking (triclinic birnessite containing predominantly Mn(III) substitutions). Structural analyses suggest that during aging at pH 4, Mn(II) adsorbs above vacancies and promotes the formation of phyllomanganates with rotationally ordered sheets and mixed symmetries arranged into supercells, while structural Mn(III) undergoes disproportionation. These structural changes at pH 4 correlate with reduced Mn(II) uptake onto triclinic and hexagonal birnessite after 25 days relative to 48 h of reaction, indicating that phyllomanganate reactivity decreases upon aging with Mn(II), or that recrystallization processes involving Mn(II) uptake occur over 25 days. At pH 7, Mn(II) adsorbs and causes limited structural effects, primarily increasing sheet stacking in δ-MnO2. These results show that aging-induced structural changes in phyllomanganates are affected by aqueous Mn(II), pH, and initial solid-phase Mn(III) content. Such restructuring likely alters manganese oxide reactions with other constituents in environmental and geologic systems

  10. Endothelial AT₁ and AT₂ pathways in aortic responses to angiotensin II after stress and ethanol consumption in rats.

    PubMed

    Baptista, Rafaela de Fátima Ferreira; Chies, Agnaldo Bruno; Taipeiro, Elane de Fátima; Cordellini, Sandra

    2014-12-01

    Stress and ethanol are important cardiovascular risk factors. Their vascular and blood pressure (BP) effects were evaluated alone and in combination. Adult male Wistar rats (8-10 per group) were separated into control, ethanol (ethanol 20% in drinking water for 6 weeks), stress (restraint 1 h/d 5 d/week for 6 weeks), and ethanol/stress (in combination) groups. Systolic BP was evaluated weekly. Concentration-response curves for contractile responses to angiotensin II in the absence and the presence of losartan (AT1-blocker), PD123-319 (AT2-blocker), L-NAME (nitric oxide synthase inhibitor), or indomethacin (cyclooxygenase inhibitor) were obtained in isolated intact and endothelium-denuded aortas. Effective concentration 50% (EC50) and maximum response (MR) were compared among groups using MANOVA/Tukey tests. Stress and stress plus ethanol increased BP. Ethanol and stress, alone and in combination, did not alter angiotensin responses of intact aortas. PD123-319 decreased MR to angiotensin II in intact aortas from the ethanol and ethanol/stress groups relative to control in the presence of PD123-319. Losartan increased MR to angiotensin II in intact aortas from the stress and ethanol/stress groups relative to control in the presence of losartan. None of the protocols altered angiotensin responses of denuded aortas. Neither indomethacin nor L-NAME altered angiotensin responses of intact aortas from the experimental groups. Thus ethanol and ethanol plus stress may alter endothelial signaling via AT1-receptors, without changing systemic BP. Stress and stress plus ethanol may alter endothelial signaling via AT2-receptors, and thereby increase BP. Knowledge of such vascular changes induced by stress and/or ethanol may contribute to understanding adverse cardiovascular effects of stress and ethanol consumption in humans.

  11. Flocculation of copper(II) and tetracycline from water using a novel pH- and temperature-responsive flocculants.

    PubMed

    Yang, Zhen; Jia, Shuying; Zhuo, Ning; Yang, Weiben; Wang, Yuping

    2015-12-01

    Insufficient research is available on flocculation of combined pollutants of heavy metals and antibiotics, which widely exist in livestock wastewaters. Aiming at solving difficulties in flocculation of this sort of combined pollution, a novel pH- and temperature-responsive biomass-based flocculant, carboxymethyl chitosan-graft-poly(N-isoproyl acrylamide-co-diallyl dimethyl ammonium chloride) (denoted as CND) with two responsive switches [lower critical solution temperature (LCST) and isoelectric point (IEP)], was designed and synthesized. Its flocculation performance at different temperatures and pHs was evaluated using copper(II) and tetracycline (TC) as model contaminants. CND exhibited high efficiency for coremoval of both contaminants, whereas two commercial flocculants (polyaluminum chloride and polyacrylamide) did not. Especially, flocculation performance of the dual-responsive flocculant under conditions of temperature>LCST and IEP(contaminants)II) and TC were present in bridging flocculation, including charge attraction, coordination and hydrophobic effect. Based on these pairwise interactions, copper(II) and TC exerted "aid" roles to each other's removal with the existence of CND, and preferable flocculation performance was thus achieved.

  12. Roles of an unconventional protein kinase and myosin II in amoeba osmotic shock responses.

    PubMed

    Betapudi, Venkaiah; Egelhoff, Thomas T

    2009-12-01

    The contractile vacuole (CV) is a dynamic organelle that enables Dictyostelium amoeba and other protist to maintain osmotic homeostasis by expelling excess water. In the present study, we have uncovered a mechanism that coordinates the mechanics of the CV with myosin II, regulated by VwkA, an unconventional protein kinase that is conserved in an array of protozoa. Green fluorescent protein (GFP)-VwkA fusion proteins localize persistently to the CV during both filling and expulsion phases of water. In vwkA null cells, the established CV marker dajumin still localizes to the CV, but these structures are large, spherical and severely impaired for discharge. Furthermore, myosin II cortical localization and assembly are abnormal in vwkA null cells. Parallel analysis of wild-type cells treated with myosin II inhibitors or of myosin II null cells also results in enlarged CVs with impaired dynamics. We suggest that the myosin II cortical cytoskeleton, regulated by VwkA, serves a critical conserved role in the periodic contractions of the CV, as part of the osmotic protective mechanism of protozoa.

  13. The effect of intrafetal infusion of metyrapone on arterial blood pressure and on the arterial blood pressure response to angiotensin II in the sheep fetus during late gestation

    PubMed Central

    Warnes, K E; Coulter, C L; Robinson, J S; McMillen, I C

    2003-01-01

    While the impact of exogenous glucocorticoids on the fetal cardiovascular system has been well defined, relatively few studies have characterised the role of endogenous fetal glucocorticoids in the regulation of arterial blood pressure (BP) during late gestation. We have therefore infused metyrapone, an inhibitor of cortisol biosynthesis, into fetal sheep from 125 days gestation (when fetal cortisol concentrations are low) and from 137 days gestation (when fetal cortisol concentrations are increasing) and measured fetal plasma cortisol, 11-desoxycortisol and ACTH, fetal systolic, diastolic and mean arterial BP, heart rate, and the fetal BP responses to increasing doses of angiotensin II (AII). At 125 days gestation, there was a significant increase in fetal plasma ACTH and 11-desoxycortisol by 24 h after (+24 h) the start of the metyrapone infusion, and plasma cortisol concentrations were not different at +24 h when compared with pre-infusion values. Whilst the initial fall in circulating cortisol concentrations may have been transient, systolic, diastolic and mean arterial BP were ∼5–6 mmHg lower (P < 0.05) in metyrapone- than in vehicle-infused fetuses at 24–48 h after the start of the infusion. When metyrapone was infused from 137/138 days gestation, there was a significant decrease in plasma cortisol concentrations by +6 h, which was followed by an increase back to pre-infusion values. While cortisol concentrations decreased, there was no change in fetal mean arterial BP during the first 24 h after the start of metyrapone infusion. Mean fetal arterial BP values at 137–139 days gestation were not different in fetuses that had been infused with either vehicle or metyrapone from 125 days gestation or with metyrapone from 137–138 days gestation. At 137–139 days gestation, however, arterial BP responses to increasing doses of AII were significantly blunted in fetuses that had been infused with metyrapone from 125 days gestation, when compared with

  14. A graphical and analytical method to determine the transient response for an ideal transmission line, loaded by a time-varying impedance

    SciTech Connect

    Krehl, P.; Novender, W.R.

    1985-04-01

    Based on Bergeron's theory, a graphical and analytical method has been worked out to determine the dynamic load characteristic and load transients for a time-varying load impedance, pulsed by a lossless transmission line. The analytical solution has been compared with the numerical solution of the network analysis code SCEPTRE. A parametric study for a time-decreasing load function, demonstrated by the example of a vacuum-discharge flash X-ray tube, reveals that the dynamic load characteristic I /SUB L/ (U /SUB L/ (t),U/sub 0/,Z/sub 0/,T) and the transients U /SUB L/ (t,U/sub 0/,Z/sub 0/,T) and I /SUB L/ (t,U/sub 0/,Z/sub 0/,T) are dependent on the diode function Z /SUB L/ (t) as well as on the charging voltage U/sub 0/ and the characterics T and Z/sub 0/ of the line.

  15. Selective reduction of fMRI responses to transient achromatic stimuli in the magnocellular layers of the LGN and the superficial layer of the SC of early glaucoma patients.

    PubMed

    Zhang, Peng; Wen, Wen; Sun, Xinghuai; He, Sheng

    2016-02-01

    Glaucoma is now viewed not just a disease of the eye but also a disease of the brain. The prognosis of glaucoma critically depends on how early the disease can be detected. However, early glaucomatous loss of the laminar functions in the human lateral geniculate nucleus (LGN) and superior colliculus (SC) remains difficult to detect and poorly understood. Using functional MRI, we measured neural signals from different layers of the LGN and SC, as well as from the early visual cortices (V1, V2 and MT), in patients with early-stage glaucoma and normal controls. Compared to normal controls, early glaucoma patients showed more reduction of response to transient achromatic stimuli than to sustained chromatic stimuli in the magnocellular layers of the LGN, as well as in the superficial layer of the SC. Magnocellular responses in the LGN were also significantly correlated with the degree of behavioral deficits to the glaucomatous eye. Finally, early glaucoma patients showed no reduction of fMRI response in the early visual cortex. These findings demonstrate that 'large cells' in the human LGN and SC suffer selective loss of response to transient achromatic stimuli at the early stage of glaucoma. Hum Brain Mapp 37:558-569, 2016. © 2015 Wiley Periodicals, Inc.

  16. Sex differences in angiotensin II responses contribute to a differential regulation of cox-mediated vascular dysfunction during aging.

    PubMed

    Costa, Gustavo; Garabito, Manel; Jiménez-Altayó, Francesc; Onetti, Yara; Sabate, Manel; Vila, Elisabet; Dantas, Ana Paula

    2016-12-01

    Aging is a cardiovascular risk factor partially related to activation of the Renin-Angiotensin System (RAS). RAS activation is also influenced by sex. In this regard, our study aims to determine whether sex-associated differences in RAS contribute to a differential regulation of vascular aging and associated dysfunction. Male and female outbreed CD-1 mice were studied at 3 and 12months of age (M). Contribution of RAS was determined by treating mice from 3M to 12M with the AngII type 1 receptor blocker losartan (0.6g/L in the drinking water). At 12M, contractions to AngII were higher in males compared to females (P<0.05). This effect was paralleled by a decrease in AngII type 2 receptors in 12M males. Aging also diminished ACh relaxation in males, but did not modify female responses. Treatment of aortas with indomethacin (10μM) restored the impaired endothelium-dependent relaxation in 12M males, suggesting an increase of cyclooxygenase (COX)-derived vasoconstrictors in aged males. Chronic treatment of mice with losartan also improved endothelium-dependent relaxation. Besides, losartan significantly decreased COX-2 expression and activity in 12M male, with a minor effect in aged females. Aging increases AngII contraction and induces endothelial dysfunction differently in males and females. In aged males, RAS contributed to increased COX-2 expression and activity, which in turn may lead to vascular dysfunction.

  17. Impaired drinking response in histamine H3 receptor knockout mice following dehydration or angiotensin-II challenge.

    PubMed

    Yoshimoto, Ryo; Miyamoto, Yasuhisa; Takahashi, Kazuhiko; Kotani, Hidehito; Kanatani, Akio; Tokita, Shigeru

    2006-07-01

    Histamine H3 receptors (H3Rs) are presynaptic receptors that negatively regulate the release of histamine. The present study examined the physiological role of H3Rs in drinking behavior. In water-replete rats, intracerebroventricular (i.c.v.) administration of R-alpha-methylhistamine (RalphaMeHA), an H3R agonist, elicited drinking behavior. In contrast, i.c.v. administration of thioperamide, an H3R inverse agonist, significantly attenuated the drinking behavior elicited by either overnight dehydration or i.c.v. administration of angiotensin-II (AT-II). Inhibition of histamine release with alpha-fluoromethylhistidine, an inhibitor of histidine decarboxylase, did not elicit drinking behavior. Moreover, the inhibitory effects of thioperamide on drinking behavior in water-depleted rats were not mimicked by i.c.v. administration of histamine. These results suggest that the predominant effects of H3Rs on drinking behavior are not mediated by the modulation of histamine release. In H3R-deficient (H3RKO) mice, drinking behavior induced by overnight dehydration or i.c.v. administration of AT-II was significantly impaired compared to wild type mice. Collectively, these observations suggest that brain H3Rs play a pivotal role in drinking behavior in response to dehydration and AT-II, and these effects may be largely independent of the modulation of histaminergic tone.

  18. Toward agricultural sustainability through integrated crop–livestock systems. II. Production responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Intensification of cropping and animal production as two separately specialized agricultural systems has led to unacceptable deterioration of the environment due to (i) excessive concentration of nutrients and pathogens in livestock production systems and (ii) loss of natural biodiversity and excess...

  19. Role of multilayer-like interference effects on the transient optical response of Si{sub 3}N{sub 4} films pumped with free-electron laser pulses

    SciTech Connect

    Casolari, F.; Giangrisostomi, E.; Bencivenga, F.; Capotondi, F.; Manfredda, M.; Pedersoli, E.; Principi, E.; Masciovecchio, C.; Kiskinova, M.; Mincigrucci, R.

    2014-05-12

    X-ray/optical cross-correlation methods are attracting increasing interest for exploring transient states of matter using ultrashort free-electron laser (FEL) pulses. Our paper shows that in such studies the difference in the penetration depth of the FEL-pump and the infrared (IR) probe pulses become important, in particular, when exploring the changes in the optical properties of solid targets. We discuss the role of interference effects, using a phenomenological model with excited and unperturbed slabs. The reliability of this model was experimentally verified by measuring the transient optical response of free-standing and silicon (Si) supported silicon nitride (Si{sub 3}N{sub 4}) films, simultaneously in reflection and transmission, using s- and p-polarized IR light. The changes in the Si{sub 3}N{sub 4} optical refractive index, induced by the FEL pulses, have fully been described in the frame of the proposed model. The experimental results confirm that the differences, observed in the FEL-induced transient reflectance and transmittance of the Si{sub 3}N{sub 4} targets with different thicknesses, arise from multilayer-like interferometric phenomena.

  20. Centrifugal Modelling of Transient Water Flow in Earth Embankments.

    DTIC Science & Technology

    1980-05-07

    Redshaw [10] in their recent book and the transient flow net technique described by Cedergren Approximate Solutions The solution of the transient flow...and Foundation Engineering, Paris, Vol. II, pp. 551-554. 3. Cedergren , H.R., Seepage, Drainage, and Flow Nets, 2nd Ed., New York, John Wiley & Sons

  1. Transient generation of hydrogen peroxide is responsible for carcinostatic effects of hydrogen combined with platinum nanocolloid, together with increases intracellular ROS, DNA cleavages, and proportion of G2/M-phase.

    PubMed

    Saitoh, Yasukazu; Ikeshima, Minoru; Kawasaki, Naho; Masumoto, Aoi; Miwa, Nobuhiko

    2016-01-01

    In our previous study, we demonstrated that combined treatment with hydrogen (H2) and platinum nanocolloid (Pt-nc) exerted markedly antiproliferative effects on cancer cells compared with each treatment alone. However, because the related mechanisms remain unclear, we investigated carcinostatic mechanisms of the combined treatment with H2 + Pt-nc. Significant suppression of cell proliferation was confirmed at 52 h following combined treatment, and the similar effect was also observed by the 30- or 40-min transient treatment with H2 + Pt-nc. The transient treatments led to changes in cell size and morphology, loss of microvilli, and apoptosis-like cell death at 120 h after treatment. Moreover, transient combined treatment with H2 + Pt-nc induced cell-cycle arrest, as reflected by decreased proportions of G1-phase cells and accumulation of G2/M-phase cells. In contrast, intracellular peroxide levels were temporarily and significantly increased immediately after H2 + Pt-nc treatment but not after treatment with H2 or Pt-nc alone. Additionally, combined treatment-induced carcinostatic effects were significantly diminished in the presence of catalase, and marked hydrogen peroxide (H2O2) generation was confirmed after mixing Pt-nc into cell culture media containing a high concentration of H2. These changes are in agreement with the results that carcinostatic effects were induced after only 40 min of treatment with H2 + Pt-nc. Thus, transient and marked generation of H2O2 is responsible for the carcinostatic effects of combined treatment with H2 + Pt-nc.

  2. DNA damage response (DDR) induced by topoisomerase II poisons requires nuclear function of the small GTPase Rac.

    PubMed

    Wartlick, Friedrich; Bopp, Anita; Henninger, Christian; Fritz, Gerhard

    2013-12-01

    Here, we investigated the influence of Rac family small GTPases on mechanisms of the DNA damage response (DDR) stimulated by topoisomerase II poisons. To this end, we examined the influence of the Rac-specific small molecule inhibitor EHT1864 on Ser139 phosphorylation of histone H2AX, a widely used marker of the DDR triggered by DNA double-strand breaks. EHT1864 attenuated the doxorubicin-stimulated DDR in a subset of cell lines tested, including HepG2 hepatoma cells. EHT1864 reduced the level of DNA strand breaks and increased viability following treatment of HepG2 cells with topo II poisons. Protection by EHT1864 was observed in both p53 wildtype (HepG2) and p53 deficient (Hep3B) human hepatoma cells and, furthermore, remained unaffected upon pharmacological inhibition of p53 in HepG2. Apparently, the impact of Rac on the DDR is independent of p53. Protection from doxorubicin-induced DNA damage by EHT1864 comprises both S and G2 phase cells. The inhibitory effect of EHT1864 on doxorubicin-stimulated DDR was mimicked by pharmacological inhibition of various protein kinases, including JNK, ERK, PI3K, PAK and CK1. EHT1864 and protein kinase inhibitors also attenuated the formation of the topo II-DNA cleavable complex. Moreover, EHT1864 mitigated the constitutive phosphorylation of topoisomerase IIα at positions S1106, S1213 and S1247. Doxorubicin transport, nuclear import/export of topoisomerase II and Hsp90-related mechanisms are likely not of relevance for doxorubicin-stimulated DDR impaired by EHT1864. We suggest that multiple kinase-dependent but p53- and heat shock protein-independent Rac-regulated nuclear mechanisms are required for activation of the DDR following treatment with topo II poisons.

  3. Angiotensin II has acute effects on TRPC6 channels in podocytes of freshly isolated glomeruli

    PubMed Central

    Ilatovskaya, Daria V.; Palygin, Oleg; Chubinskiy-Nadezhdin, Vladislav; Negulyaev, Yuri A.; Ma, Rong; Birnbaumer, Lutz; Staruschenko, Alexander

    2014-01-01

    A key role for podocytes in the pathogenesis of proteinuric renal diseases has been established. Angiotensin II causes depolarization and increased intracellular calcium concentration in podocytes; members of the cation TRPC channels family, particularly TRPC6, are proposed as proteins responsible for calcium flux. Angiotensin II evokes calcium transient through TRPC channels and mutations in the gene encoding the TRPC6 channel result in the development of focal segmental glomerulosclerosis. Here we examined the effects of angiotensin II on intracellular calcium ion levels and endogenous channels in intact podocytes of freshly isolated decapsulated mouse glomeruli. An ion channel with distinct TRPC6 properties was identified in wild type, but was absent in TRPC6 knockout mice. Single channel electrophysiological analysis found that angiotensin II acutely activated native TRPC-like channels in both podocytes of freshly isolated glomeruli and TRPC6 channels transiently overexpressed in CHO cells; the effect was mediated by changes in the channel open probability. Angiotensin II evoked intracellular calcium transients in the wild type podocytes, which was blunted in TRPC6 knockout glomeruli. Pan-TRPC inhibitors gadolinium and SKF 96365 reduced the response in wild type glomerular epithelial cells, whereas the transient in TRPC6 knockout animals was not affected. Thus, angiotensin II-dependent activation of TRPC6 channels in podocytes may have a significant role in the development of kidney diseases. PMID:24646854

  4. Spectral signatures of penumbral transients

    SciTech Connect

    Reardon, K.; Tritschler, A.

    2013-12-20

    In this work we investigate the properties of penumbral transients observed in the upper photospheric and chromospheric region above a sunspot penumbra using two-dimensional spectroscopic observations of the Ca II 854.21 nm line with a 5 s cadence. In our 30 minutes of observations, we identify several penumbral-micro jets (PMJs) with cotemporal observations from Dunn Solar Telescope/IBIS and Hinode/SOT. We find that the line profiles of these PMJ events show emission in the two wings of the line (±0.05 nm), but little modification of the line core. These are reminiscent of the line profiles of Ellerman bombs observed in plage and network regions. Furthermore, we find evidence that some PMJ events have a precursor phase starting 1 minute prior to the main brightening that might indicate initial heating of the plasma prior to an acoustic or bow shock event. With the IBIS data, we also find several other types of transient brightenings with timescales of less than 1 minute that are not clearly seen in the Hinode/SOT data. The spectral profiles and other characteristics of these events are significantly different from those of PMJs. The different appearances of all these transients are an indicator of the general complexity of the chromospheric magnetic field and underscore the highly dynamic behavior above sunspots. It also highlights the care that is needed in interpreting broadband filter images of chromospheric lines, which may conceal very different spectral profiles, and the underlying physical mechanisms at work.

  5. A shear deformable theory of laminated composite shallow shell-type panels and their response analysis. II - Static response

    NASA Technical Reports Server (NTRS)

    Khdeir, A. A.; Librescu, L.; Frederick, D.

    1989-01-01

    In the second part of this paper, by using the static counterparts of the governing equations derived in Librescu (1989), the static response of shallow composite shell-type panels subjected to a sinusoidal transverse load is investigated. The numerical applications, encompassing a large number of boundary conditions and various lamination schemes, allow one to obtain some conclusions which are formulated in the paper.

  6. Response of a BWR Mark II containment vessel head to loads beyond the design basis

    SciTech Connect

    Kulak, R.F.; Ash, J.E.; Kennedy, J.M.; Hsieh, B.J.

    1985-01-01

    A simulation of the macro-deformations of the sealing surfaces between the removable drywell head and the conical shell of a Mark II containment vessel head during a severe accident is presented. This junction contains two continuous gaskets in a configuration classified as non-pressure seating. An examination of the behavior of this junction to pressure and thermal loadings is reported. 5 refs., 7 figs.

  7. Genetic variability in swine leukocyte antigen class II and Toll-like receptors affects immune responses to vaccination for bacterial infections in pigs.

    PubMed

    Shinkai, H; Arakawa, A; Tanaka-Matsuda, M; Ide-Okumura, H; Terada, K; Chikyu, M; Kawarasaki, T; Ando, A; Uenishi, H

    2012-12-01

    The genes encoding swine leukocyte antigen (SLA) and Toll-like receptor (TLR) are highly polymorphic in pig populations, and likely have influences on infection and the effects of vaccination. We explored the associations of different genotypes of SLA class II and of the genes TLR1, TLR4, TLR5, and TLR6 with antibody responses after vaccination against Erysipelothrix rhusiopathiae (ER) and Actinobacillus pleuropneumoniae (APP) serotypes 1, 2, and 5 in 191 Duroc pigs maintained under specific pathogen-free conditions. We demonstrated close relationships between SLA class II and ER antibody response and between TLR genes other than TLR4 and APP antibody responses. Pigs with specific haplotypes in SLA class II or TLR5 showed decreased antibody response to ER vaccination or increased responses to APP2 and APP5 vaccination, respectively. It might be possible to breed for responsiveness to vaccination and to implement new vaccine development strategies unaffected by genetic backgrounds of pigs.

  8. Intracellular photoactivation of caged cGMP induces myosin II and actin responses in motile cells.

    PubMed

    Pfannes, Eva K B; Anielski, Alexander; Gerhardt, Matthias; Beta, Carsten

    2013-12-01

    Cyclic GMP (cGMP) is a ubiquitous second messenger in eukaryotic cells. It is assumed to regulate the association of myosin II with the cytoskeleton of motile cells. When cells of the social amoeba Dictyostelium discoideum are exposed to chemoattractants or to increased osmotic stress, intracellular cGMP levels rise, preceding the accumulation of myosin II in the cell cortex. To directly investigate the impact of intracellular cGMP on cytoskeletal dynamics in a living cell, we released cGMP inside the cell by laser-induced photo-cleavage of a caged precursor. With this approach, we could directly show in a live cell experiment that an increase in intracellular cGMP indeed induces myosin II to accumulate in the cortex. Unexpectedly, we observed for the first time that also the amount of filamentous actin in the cell cortex increases upon a rise in the cGMP concentration, independently of cAMP receptor activation and signaling. We discuss our results in the light of recent work on the cGMP signaling pathway and suggest possible links between cGMP signaling and the actin system.

  9. Renal hemodynamic responses to increased renal venous pressure: role of angiotensin II.

    PubMed

    Kastner, P R; Hall, J E; Guyton, A C

    1982-09-01

    Studies were performed to quantitate the effects of progressive increases in renal venous pressure (RVP) on renin secretion (RS) and renal hemodynamics. RVP was raised in 10 mmHg increments to 50 mmHg. Renin secretion rate increased modestly as RVP was increased to 30 mmHg and then increased sharply after RVP exceeded 30 mmHg. Glomerular filtration rate (GFR), renal blood flow (RBF), and filtration fract