bluuebunny/crossref_metadata_2025 huggingface dataset:
Relaxation behind shock waves in ionizing neon
Authors: Mcintyre T. J. , Houwing A. F. P. , Sandeman R. J. , Bachor H.-A.
Published: April 2006

Experiments in ionizing neon are described in which heavy-particle and electron densities are measured and compared with the current kinetic model. The experimental results allow a determination of the atom-atom collisional excitation cross-section constant, giving a value of (8±2) × 10−20 cm2/eV for the range of conditions examined. The population of two of the excited-state levels of the atom are measured and compared with theoretical predictions. The experimental populations are found to follow the expected behaviour in the quasi-equilibrium region, but are several orders of magnitude higher than predicted in the nonequilibrium zone. These findings suggest that the depopulation of excited states through ionizing collisions occurs more slowly than expected. Absorption linewidths and line shifts are also measured in the quasi-equilibrium region and found to compare well with theory. A small precurson population is also observed and population measurements in this region are compared with other experimental results in argon and krypton.
On the linear stability of inviscid incompressible plane parallel flow
Authors: Barston E. M.
Published: April 2006

A class of constants of motion is obtained for the time-dependent form of the Rayleigh stability equation, which provides stability criteria for velocity profiles with multiple inflexion points.
Nonlinear dynamics near the stability margin in rotating pipe flow
Authors: Yang Z. , Leibovich S.
Published: April 2006

The nonlinear evolution of marginally unstable wave packets in rotating pipe flow is studied. These flows depend on two control parameters, which may be taken to be the axial Reynolds number R and a Rossby number, q. Marginal stability is realized on a curve in the (R, q)-plane, and we explore the entire marginal stability boundary. As the flow passes through any point on the marginal stability curve, it undergoes a supercritical Hopf bifurcation and the steady base flow is replaced by a travelling wave. The envelope of the wave system is governed by a complex Ginzburg–Landau equation. The Ginzburg–Landau equation admits Stokes waves, which correspond to standing modulations of the linear travelling wavetrain, as well as travelling wave modulations of the linear wavetrain. Bands of wavenumbers are identified in which the nonlinear modulated waves are subject to a sideband instability.
Edge waves on a gently sloping beach: uniform asymptotics
Authors: Zhevandrov Peter
Published: April 2006

Edge waves on a beach of gentle slope ε [Lt ] 1 are considered. For constant slope, Ursell (1952) has obtained a complete set of trapped modes and shown that there exists only a finite number n of such modes, (2n + 1)β < ½π, β = tan−1ε. For non-uniform slope the formulae for the trapped-mode frequencies were heuristically derived by Shen, Meyer & Keller (1968). For small n ∼ O(1) Miles (1989) has obtained formulae which coincide with Shen et al.'s (1968) with accuracy to O(ε) and differ from them by O(ε2). However, Miles’ formulae fail at n ∼ 1/ε. In this paper it is proved that Shen et al.'s (1968) formulae are valid for all n (including n ∼ 1/ε) with accuracy to O(ε) and corrections of any order in ε are given. Uniform asymptotic expansions are obtained for the corresponding eigenfunctions. These expansions give Miles’ (1989) result for small n. The formulae for the frequencies and the eigenfunctions have the same structure for both the full dispersion system and the shallow-water equation. For small n the frequencies for both models coincide with accuracy to O(ε2), but for n ∼ 1/ε they differ by O(1). In the last section the effect of rotation following Evans (1989) is taken into account. All the asymptotics have formal character, i.e. they satisfy the corresponding equations with accuracy to O(εN), N being arbitrarily large. The rigorous justification of these asymptotics is under way.
Self-induced flow in a rotating tube
Authors: Gilham S. , Ivey P. C. , Owen J. M. , Pincombe J. R.
Published: April 2006

When a tube, sealed at one end and open to a quiescent environment at the other, is rotated about its axis, fluid flows from the open end along the axis towards the sealed end and returns in an annular boundary layer on the cylindrical wall. This paper describes the first known study to be made of this self-induced flow. Numerical solutions of the Navier–Stokes equations are shown to be in mainly good agreement with experimental results obtained using flow visualization and laser–Doppler anemometry in a rotating glass tube.

The self-induced flow in the tube can be described in terms of the length-to-radius ratio, G, and the Ekman number, E. However, for large values of G (G [ges ] 20), the flow outside the boundary layer on the endwall of the tube can be characterized by a single, modified, Ekman number, E*, where E* = GE. Although most of the fluid entering the open end of the tube is entrained into the annular (Stewartson-type) boundary layer, for small values of E* (E* < 0.2) some flow reaches the sealed end. For this so-called 'short-tube case’, the flow in the boundary layer on the endwall is shown to be similar to that associated with a disk rotating in a quiescent environment: the free disk. The self-induced flow for the short-tube case is believed to be responsible for the ’ hot-poker effect’ used, on some jet engines, to provide ice protection for the nose bullet.
Collision of two vortex rings
Authors: Kida S. , Takaoka M. , Hussain F.
Published: April 2006

The interaction of two identical circular viscous vortex rings starting in a side-by-side configuration is investigated by solving the Navier–Stokes equation using a spectral method with 643grid points. This study covers initial Reynolds numbers (ratio of circulation to viscosity) up to 1153. The vortices undergo two successive reconnections,fusionandfission, as has been visualized experimentally, but the simulation shows topological details not observed in experiments. The shapes of the evolving vortex rings are different for different initial conditions, but the mechanism of the reconnection is explained bybridging(Melander & Hussain 1988) except that the bridges are created on the front of the dipole close to the position of the maximum strain rate. Spatial structures of various field quantities are compared. It is found that domains of high energy dissipation and high enstrophy production overlap, and that they are highly localized in space compared with the regions of concentrated vorticity. The kinetic energy decays according to the same power laws as found in fully developed turbulence, consistent with concentrated regions of energy dissipation. The main vortex cores survive for a relatively long time. On the other hand, the helicity density which is higher in roots of bridges and threads (or legs) changes rapidly in time. The high-helicity-density and high-energy-dissipation regions overlap significantly although their peaks do not always do so. Thus a long-lived structure may carry high-vorticity rather than necessarily high-helicity density. It is shown that the time evolution of concentration of a passive scalar is quite different from that of the vorticity field, confirming our longstanding warning against relying too heavily on flow visualization in laboratory experiments for studying vortex dynamics and coherent structures.
Linear and nonlinear barotropic instability of geostrophic shear layers
Authors: Pratt L. J. , Pedlosky J.
Published: April 2006

The linear, weakly nonlinear and strongly nonlinear evolution of unstable waves in a geostrophic shear layer is examined. In all cases, the growth of initially small-amplitude waves in the periodic domain causes the shear layer to break up into a series of eddies or pools. Pooling tends to be associated with waves having a significant varicose structure. Although the linear instability sets the scale for the pooling, the wave growth and evolution at moderate and large amplitudes is due entirely to nonlinear dynamics. Weakly nonlinear theory provides a catastrophic time ts at which the wave amplitude is predicted to become infinite. This time gives a reasonable estimate of the time observed for pools to detach in numerical experiments with marginally unstable and rapidly growing waves.
On resonant nonlinear bubble oscillations
Authors: Williams J. E. Ffowcs , Guo Y. P.
Published: April 2006

If a bubble were produced with an initial surface distortion, the energy carried by surface modes could be converted to other modes by nonlinear interaction, a conversion that provides a possible mechanism of second generation by bubbles. Longuet-Higgins (1989a,b) has argued that volume pulsation would be excited at twice the frequency of the distortion mode and that the response to such excitation is ‘surprisingly large’ when its frequency is close to the natural resonance frequency of the volumetrical mode. It is shown in this paper that this is feasible only if the driving system is sufficiently energetic to supply the energy involved in those volume pulsations, and that this is not generally the case. In the absence of external sources, the sum of energies in the interacting modes cannot exceed the initial bubble energy; an increase in one mode is always accompanied by a decrease in another. In contrast to any expectation of significant pulsations near resonance, we find that, once modal coupling is admitted, the volumetrical pulsation has very small amplitude in comparison with that of the initial surface distortion. This is because of the constraint of energy, a constraint that becomes more severe once damping is admitted. Our conclusion therefore is that the distortion modes of a bubble are unlikely to be the origin of an acoustically significant bubble response.
On the evolution of a wave packet in a laminar boundary layer
Authors: Cohen Jacob , Breuer Kenneth S. , Haritonidis Joseph H.
Published: April 2006

The transition process of a small-amplitude wave packet, generated by a controlled short-duration air pulse, to the formation of a turbulent spot is traced experimentally in a laminar boundary layer. The vertical and spanwise structures of the flow field are mapped at several downstream locations. The measurements, which include all three velocity components, show three stages of transition. In the first stage, the wave packet can be treated as a superposition of two- and three-dimensional waves according to linear stability theory, and most of the energy is centred around a mode corresponding to the most amplified wave. In the second stage, most of the energy is transferred to oblique waves which are centred around a wave having half the frequency of the most amplified linear mode. During this stage, the amplitude of the wave packet increases from 0.5 % to 5 % of the free-stream velocity. In the final stage, a turbulent spot develops and the amplitude of the disturbance increases to 27 % of the free-stream velocity.

Theoretical aspects of the various stages are considered. The amplitude and phase distributions of various modes of all three velocity components are compared with the solutions provided by linear stability theory. The agreement between the theoretical and measured distributions is very good during the first two stages of transition. Based on linear stability theory, it is shown that the two-dimensional mode of the streamwise velocity component is not necessarily the most energetic wave. While linear stability theory fails to predict the generation of the oblique waves in the second stage of transition, it is demonstrated that this stage appears to be governed by Craik-type subharmonic resonances.
Oscillations of liquid captive rotating drops
Authors: Gañán-Calvo A. M.
Published: April 2006

A linear analysis of the free oscillations of captive drops or bubbles is discussed. The drop is surrounded by an immiscible liquid or gas and undergoes rotation as a rigid body in the presence of gravity. Using spectral analytical methods, we provide a general formulation for both elliptic and hyperbolic oscillation regimes of the frequency spectrum, for any combination of the Weber and Bond numbers. The method uses a Green function to reduce the inviscid Navier–Stokes equations and boundary conditions to an eigenvalue problem. Both the Green function and normal velocities at the interface are expanded in the orthogonal functional space generated by the Sturm–Liouville problem associated to the interface equation. The effect on the vibration modes of the density and geometrical parameters of the captive drop and surrounding medium is analysed. We present a complete analysis of the low-frequency spectra in the elliptic regime of a set of floating liquid zones and captive drops for a continuous range of Weber and Bond numbers. It is shown that, depending on the geometrical parameters of the system, the elliptic vibration spectrum presents a sui generis modal interaction for low wavenumbers and certain ranges of Weber number.
Evolution of stream wise vortices and generation of small-scale motion in a plane mixing layer
Authors: Nygaard K. J. , Glezer A.
Published: April 2006

The evolution of streamwise vortices in a plane mixing layer and their role in the generation of small-scale three-dimensional motion are studied in a closed-return water facility. Spanwise-periodic streamwise vortices are excited by a time-harmonic wavetrain with span wise-periodic amplitude variations synthesized by a mosaic of 32 surface film heaters flush-mounted on the flow partition. For a given excitation frequency, virtually any span wise wavelength synthesizable by the heating mosaic can be excited and can lead to the formation of streamwise vortices before the rollup of the primary vortices is completed. The onset of streamwise vortices is accompanied by significant distortion in the transverse distribution of the streamwise velocity component. The presence of inflexion points, absent in corresponding velocity distributions of the unforced flow, suggests the formation of locally unstable regions of large shear in which broadband perturbations already present in the base flow undergo rapid amplification, followed by breakdown to small-scale motion. Furthermore, as a result of spanwise-non-uniform excitation the cores of the primary vortices are significantly altered. The three-dimensional features of the streamwise vortices and their interaction with the base flow are inferred from surfaces of r.m.s. velocity fluctuations and an approximation to cross-stream vorticity using three-dimensional single component velocity data. The striking enhancement of small-scale motion and the spatial modification of its distribution, both induced by the streamwise vortices, can be related to the onset of the mixing transition.
Capillarity effects on surface gravity waves in a cylindrical container: wetting boundary conditions
Authors: Cocciaro Bruno , Faetti Sandro , Nobili Maurizio
Published: April 2006

Surface capillary–gravity waves are experimentally investigated in a cylindrical basin subjected to a horizontal oscillation by using a high-sensitivity optical method. We study the low-oscillation-amplitude regimes for a fluid which wets the vertical walls and we show that the presence of the capillary meniscus can effect greatly the main properties of the system. Both the free decay and the forced oscillations of surface oscillations are investigated. The amplitude, the phase and the damping of gravity waves are investigated in detail. The damping of the fundamental surface mode is found to exhibit nonlinear behaviour which is in qualitative agreement with the predictions of the Miles (1967) theory of capillary damping. The amplitude and the phase of gravity waves with respect to the oscillation of the container exhibit unusual behaviour which is strictly connected with the presence of the wetting boundary condition for the fluid at the vertical walls.
Dynamical analysis of electrochemical wall shear rate measurements
Authors: Van Steenhoven A. A. , Van De Beucken F. J. H. M.
Published: April 2006

The performance of a circular electrochemical wall shear rate probe under unsteady flow conditions is analysed through a combined experimental, numerical and analytical approach. The experiments arc performed with a ferri- and ferrocyanide redox couple and compared to finite element analyses of the two-dimensional time-dependent convection—diffusion equation. The results are related to the analytical Lévêque solution for steady flow and for some cases to Pedley's model for heat transfer in reversing shear flow (Pedley 1976).

The steady flow analyses showed that in our experiments axial diffusion is only of minor importance but that for the lower Péclet numbers (< 104) three-dimensional effects, like tangential diffusion, may not be neglected. A similar result is found for the oscillating case. A fair agreement is found between experimental and numerical data during flow acceleration, but during flow reversal remarkable (about 15%) deviations are found. The observed insensitivity of the transducer during flow reversal is quite well predicted by Pedley's model. Finally, the performance of the probe may be improved somewhat by a decrease in cathode length and cathode—anode distance.
Overcoming human obstacles to conservation of recreational fishery resources, with emphasis on central Europe
Authors: ARLINGHAUS ROBERT
Published: April 2006

Recreational fisheries are the dominant or sole user of many coastal and most inland fish stocks in industrialized societies. Recreational angling can negatively affect fish populations, but appropriate management approaches to address these impacts are often lacking. Overall, privately-governed European recreational fisheries systems offer suitable conditions to reconcile resource use with resource conservation because access restriction is possible, decision-making structures are simple and management scales are small. This increases the hope that the race to fish may be less pronounced than in open-access commercial fisheries. To achieve harmony between use and conservation values, a thorough understanding of the human dimension is paramount, yet approaches including this are underrepresented in contemporary recreational fisheries science and management. Based on theoretical considerations, literature review and personal experiences, this paper presents key human obstacles to the reconciliation of recreational fishery resource use and resource conservation, with emphasis on private fishing rights regimes of central Europe. Nine obstacles are identified: (1) lack of social priority; (2) lack of integrated approaches; (3) lack of cooperative institutional linkages; (4) lack of systems thinking; (5) lack of research and monitoring; (6) lack of shared values and dominance of stereotyped perceptions; (7) lack of consideration for regional fish-angler dynamics; (8) lack of objective communication of scientific findings; and (9) lack of critical self-reflection among individual anglers. Potential solutions to overcome the identified constraints briefly discussed include: (1) evaluation of the socioeconomic benefits of angling; (2) rehabilitation of ecosystem structure and function on larger scales; (3) facilitation of structured cooperation between stakeholders and management units; (4) application of complex systems approach; (5) increased funding for long-term monitoring; (6) fostering of common values of different stake-holders; (7) active adaptive management of angling effort on regional scales; (8) intensified communication of research findings; and (9) conviction of anglers to meet personal targets by more restrictive regulations. Increasing research and management efforts related to the social component of recreational fisheries will improve reconciliation of resource use and resource conservation in traditional recreational fisheries management. It is a matter of societal values whether it is judged necessary to do so on a broader scale.
Governance and Collaboration: Review Article
Authors: Durose Catherine , Rummery Kirstein
Published: April 2006

Rod Rhodes (1997) Understanding Governance: Policy Networks, Governance, Reflexivity and Accountability, Open University Press 1997.

Gerry Stoker (1998) ‘Governance as theory: five propositions’, International Journal of Social Sciences 50, 1, 17–28.

Helen Sullivan and Chris Skelcher (2002) Working across Boundaries: Collaboration in Public Services, Palgrave.

Janet Newman, Marion Barnes, Helen Sullivan, and A. Knops (2004) ‘Public participation and collaborative governance’, Journal of Social Policy 33, 203–223.

From a term used largely within political science in the mid-1990s, ‘governance’ has become a key conceptual and analytical convention adopted by social policy, largely because of its usefulness in examining questions that are key to the discipline: citizenship; welfare rights and responsibilities; accountability; legitimacy and partnership working. Clarence and Painter (1998) have constructed a useful characterisation of public policy, identifying a shift in emphasis from hierarchies, to markets and now to collaboration. Networks, ‘joined up’ governance and partnership working are now central in both policy practice and analysis. These processes are not new, but New Labour have clearly expanded and accelerated them. For New Labour, collaborative working is now perceived as central in their response to key policy challenges: improving public services, tackling social exclusion and revitalising local democracy. These processes are now evident at all levels of policy making from supranational organisations such as the European Union down to neighbourhood-based initiatives. It appears that we are moving from the closed, unitary system of government of the Westminster model to a more open, decentralised system of governance. Our conceptions of citizenship have accordingly shifted, from one based on representation to one based on active participation, particularly within local communities. Governance is an issue which concerns all levels of government and citizen participation, from international-level World Bank concerns about commitment to efficiency and accountable government, to highly devolved localised urban regeneration partnerships.
Pharmakotherapie der Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) im Erwachsenenalter
Authors: Kordon Andreas , Hofecker Fallahpour Maria
Published: April 2006

Zusammenfassung: Auch bei der ADHS im Erwachsenenalter sind - wie bei Kindern und Jugendlichen - die Stimulanzien Methylphenidat und Amphetamine unbestritten die Mittel erster Wahl. Mittlerweile belegen mehrere kontrollierte Studien die klinische Erfahrung hoher Responderraten, zuverlässiger Wirksamkeit und guter Verträglichkeit. Deshalb ist zu erwarten, dass die heutige, in vielen Ländern bei Erwachsenen noch notwendige Off-Label-Verordnung bald der Vergangenheit angehören wird. Ebenso ist aufgrund der neueren retardierten Präparate ein Wandel in der Verordnungspraxis abzusehen mit günstigen Auswirkungen auf Compliance und Befinden der Betroffenen. Von weit reichender Bedeutung ist die positive Wirkung der Stimulanzientherapie auf das Fahrverhalten im Straßenverkehr, welche bisher in Fachkreisen und in der Öffentlichkeit zu wenig Beachtung erfuhr. Neben den Stimulanzien erreichen aber auch andere Substanzen, wie zum Beispiel Mittel mit noradrenergem Angriffspunkt, zunehmend mehr Bedeutung in der ADHS-Therapie. Ihre wesentlichen Vorteile sind darin zu sehen, dass sie kein Abhängigkeitspotenzial aufweisen und komorbide affektive Störungen bessern, der Nachteil ist jedoch ihre gegenüber Stimulanzien initial geringer ausgeprägte Wirkung. Trotzdem stellen sie wichtige therapeutische Alternativen dar. Die Pharmakotherapie sollte stets eine ausführliche Aufklärung des Patienten über Nutzen und Gefahren der Behandlung beinhalten, ebenso wie psychische und somatische Begleiterkrankungen oder Komedikationen zu berücksichtigen sind. Bedeutsam ist außerdem die psychotherapeutische Unterstützung, um die Erfolge der Pharmakotherapie durch eine Veränderung im Denken, Fühlen und Verhalten zu untermauern.
Improving carrier injection in organic diodes by incorporating charge trapping molecules
Authors: Campbell I. H. , Crone B. K.
Published: April 2006

We demonstrate improved charge injection in organic diodes by incorporating charge trapping molecules near the injecting electrode that dynamically alter the effective Schottky energy barrier to carrier injection between a metal electrode and the organic electronic material. Hole injection from Al and Cu anodes into the electroluminescent polymer poly[2-methoxy,5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] was improved by incorporating C60 molecules into the polymer near the anode. In operation, electrons injected from the cathode are trapped by the C60 molecules, creating an induced dipole near the anode. We demonstrate these effects by measuring changes in diode current-voltage characteristics and built-in potentials.
Anelastic deformation of a Pd40Cu30Ni10P20 bulk metallic glass during nanoindentation
Authors: Concustell A. , Sort J. , Greer A. L. , Baró M. D.
Published: April 2006

Time-dependent deformation processes during nanoindentation have been investigated on a Pd40Cu30Ni10P20 bulk metallic glass. Deformation under constant load has been studied as a function of prior loading rate and temperature. The constant-load displacement of the indenter into the sample shows classic relaxation kinetics and reveals the importance of anelasticity for the mechanical behavior of metallic glasses at the nanoscale.
Fresh Blood and Aged Stored Blood Are Equally Efficacious in Immediately Reversing Anemia-induced Brain Oxygenation Deficits in Humans
Authors: Weiskopf Richard B. , Feiner John , Hopf Harriet , Lieberman Jeremy , Finlay Heather E. , Quah Cheng , Kramer Joel H. , Bostrom Alan , Toy Pearl
Published: April 2006

Background

Erythrocytes are transfused to treat or prevent imminent inadequate tissue oxygenation. 2,3-diphosphoglycerate concentration decreases and oxygen affinity of hemoglobin increases (P50 decreases) with blood storage, leading some to propose that erythrocytes stored for 14 or more days do not release sufficient oxygen to make their transfusion efficacious. The authors tested the hypothesis that erythrocytes stored for 3 weeks are as effective in supplying oxygen to human tissues as are erythrocytes stored for less than 5 h.

Methods

Nine healthy volunteers donated 2 units of blood more than 3 weeks before they were tested with a standard, computerized neuropsychological test (digit-symbol substitution test [DSST]) on 2 days, 1 week apart, before and after acute isovolemic reduction of their hemoglobin concentration to 7.4 and 5.5 g/dl. Volunteers randomly received autologous erythrocytes stored for either less than 5 h ("fresh") or 3 weeks ("stored") to return their hemoglobin concentration to 7.5 g/dl (double blinded). Erythrocytes of the alternate storage duration were transfused on the second experimental day. The DSST was repeated after transfusion.

Results

Acute anemia slowed DSST performance equivalently in both groups. Transfusion of stored erythrocytes with decreased P50 reversed the altered DSST (P < 0.001) to a time that did not differ from that at 7.4 g/dl hemoglobin during production of acute anemia (P = 0.88). The erythrocyte transfusion-induced DSST improvement did not differ between groups (P = 0.96).

Conclusion

Erythrocytes stored for 3 weeks are as efficacious as are erythrocytes stored for 3.5 h in reversing the neurocognitive deficit of acute anemia. Requiring fresh rather than stored erythrocytes for augmentation of oxygen delivery does not seem warranted.
Determination of Endotracheal Tube Size in a Perinatal Population
Authors: Fayoux Pierre , Devisme Louise , Merrot Olivier , Marciniak Bruno
Published: April 2006

Background

This study aimed at correlating anatomical dimensions of the larynx and trachea to age and weight in a prenatal population. Endotracheal tube size determination was then proposed according to these considerations.

Methods

Anatomical measurements were obtained during 150 fetal and infant postmortem examinations. The optimal endotracheal tube size was determined by three methods: clinically, by a pressure method using calibrated inextensible balloons, and anatomically by comparing the laryngotracheal perimeter to the tube perimeters. Based on these results, recommended tube sizes were calculated.

Results

In premature babies before 37 weeks gestation, the optimal tube size according to pressure estimation was significantly greater than that determined by anatomical measurement alone. This difference was no longer valid after 40 weeks gestation.

Conclusions

This study identified the elasticity of laryngeal structures in premature babies, allowing intubation with tube sizes greater than predicted by anatomical measurements with an increasing injury risk located in the posterior part of the glottic plane. This elasticity disappears near 40 weeks gestation, and the injury risk then predominates in the subglottic region. These results lead the authors to recommend that the size of the endotracheal tube used in the perinatal population should be based on anatomical and experimental data to limit the injury risks.
Isoflurane Neuroprotection in Rat Hippocampal Slices Decreases with Aging
Authors: Zhan Xinhua , Fahlman Christian S. , Bickler Philip E.
Published: April 2006

Background

Most in vitro neuroprotection studies with isoflurane have involved cells obtained during the embryonic or early postnatal period. However, in mature rodents, isoflurane neuroprotection does not persist. The authors determined whether neuroprotection of hippocampal slices with isoflurane decreases with aging and is due to decreased intracellular Ca regulation and survival protein phosphorylation.

Methods

Hippocampal slices from 5-day-old, 1-month-old, and 19- to 23-month-old rats were deprived of oxygen and glucose for 5-30 min in media bubbled with 1% isoflurane. Cell death was assessed in the CA1, CA3, and dentate regions, and intracellular Ca concentration was measured in CA1 neurons. N-methyl-d-aspartate receptor (NMDAR)-dependent Ca influx was measured and the phosphorylation of NMDARs, and the survival proteins Akt and mitogen-activated protein kinase p42/44 were quantified.

Results

Twenty minutes of oxygen and glucose deprivation killed approximately 40-60% of neurons in CA3 and dentate in all age groups. Isoflurane, 1%, reduced death of CA1, CA3, and dentate neurons in slices from 5-day-old rats but not those from 23-month-old rats. In 5-day slices, isoflurane attenuated NMDAR-mediated Ca influx, whereas in aging slices, Ca influx was increased protein kinase C. In aging slices, isoflurane did not increase the phosphorylation of Akt and p42/44.

Conclusions

Isoflurane neuroprotection of hippocampal slices during oxygen and glucose deprivation decreases with age. Isoflurane does not prevent large increases in intracellular Ca concentration during oxygen and glucose deprivation and does not induce the phosphorylation of the prosurvival proteins in aging slices. A protein kinase C-mediated increase in NMDAR activity may result in increased excitotoxicity and decreased neuroprotection by volatile anesthetics in the aging brain.
Infarct-remodeled Myocardium Is Receptive to Protection by Isoflurane Postconditioning
Authors: Feng Jianhua , Fischer Gregor , Lucchinetti Eliana , Zhu Min , Bestmann Lukas , Jegger David , Arras Margarete , Pasch Thomas , Perriard Jean-Claude , Schaub Marcus C. , Zaugg Michael
Published: April 2006

Background

Postinfarct remodeled myocardium exhibits numerous structural and biochemical alterations. So far, it is unknown whether postconditioning elicited by volatile anesthetics can also provide protection in the remodeled myocardium.

Methods

Myocardial infarct was induced in male Wistar rats by ligation of the left anterior descending coronary artery. Six weeks later, hearts were buffer-perfused and exposed to 40 min of ischemia followed by 90 min of reperfusion. Anesthetic postconditioning was induced by 15 min of 2.1 vol% isoflurane. In some experiments, LY294002 (15 microM), a phosphatidylinositol 3-kinase inhibitor, was coadministered with isoflurane. Masson's trichrome staining, immunohistochemistry, Western blot analysis, and reverse-transcription polymerase chain reaction served to confirm remodeling. In buffer-perfused hearts, functional recovery was recorded, and acute infarct size was measured using 1% triphenyltetrazolium chloride staining and lactate dehydrogenase release during reperfusion. Western blot analysis was used to determine phosphorylation of reperfusion injury salvage kinases including protein kinase B/Akt and its downstream targets after 15 min of reperfusion.

Results

Infarct hearts exhibited typical macroscopic and molecular changes of remodeling. Isoflurane postconditioning improved functional recovery and decreased acute infarct size, as determined by triphenyltetrazolium (35 +/- 5% in unprotected hearts vs. 8 +/- 3% in anesthetic postconditioning; P < 0.05) and lactate dehydrogenase release. This protection was abolished by LY294002, which inhibited phosphorylation of protein kinase B/Akt and its downstream targets glycogen synthase kinase 3beta, endothelial nitric oxide synthase, and p70S6 kinase.

Conclusions

Infarct-remodeled myocardium is receptive to protection by isoflurane postconditioning via protein kinase B/Akt signaling. This is the first time to demonstrate that anesthetic postconditioning retains its marked protection in diseased myocardium.
Effect of Postoperative Experiences on Willingness to Pay to Avoid Postoperative Pain, Nausea, and Vomiting
Authors: van den Bosch Jolanda E. , Bonsel Gouke J. , Moons Karel G. , Kalkman Cor J.
Published: April 2006

Background

The authors assessed the willingness to pay (WTP) for "perfect" prophylactic antiemetics and analgesics in patients who were scheduled to undergo surgery during general anesthesia. Furthermore, they determined whether postoperative experiences of pain and nausea and vomiting (PONV) changed patients' WTP.

Methods

Data were collected alongside a randomized clinical trial that investigated the incidence of PONV in patients anesthetized with either inhalation anesthesia or total intravenous anesthesia. A subset of 808 consecutive patients participating in the trial completed WTP questionnaires 1 day before and 2 weeks after surgery. The outcome measure was the maximum amount of money that patients were willing to pay for "perfect" antiemetics and analgesics. Preoperative WTP and individual WTP changes after surgery were analyzed in relation to baseline characteristics and postoperative pain and PONV experiences.

Results

Prevention of postoperative pain was valued higher than prevention of PONV. The median preoperative WTP for analgesics was US dollar 35 (interquartile range, dolalr 7-69) vs. US dollar 17 (interquartile range, dollar 7-69) for antiemetics. Individual WTP changes for antiemetics were not related to PONV experience, whereas severe postoperative pain (numerical rating score > or = 8) was associated with an increase in the WTP for analgesics.

Conclusions

Severe postoperative pain experiences increased patients' WTP for analgesics, but PONV did not increase WTP for antiemetics. The elicited WTP values were lower than those reported in previous studies, which is possibly related to differences in market culture or patients' attitudes toward postoperative pain, nausea, and vomiting.
Major Histocompatibility Complex Haplotype Is Associated with Postherpetic Pain in Mice
Authors: Sato-Takeda Masako , Takasaki Ichiro , Takeda Kenji , Sasaki Atsushi , Andoh Tsugunobu , Nojima Hiroshi , Shiraki Kimiyasu , Kuraishi Yasushi , Hanaoka Kazuo , Tokunaga Katsushi , Yabe Toshio
Published: April 2006

Background

Postherpetic neuralgia is one of the major complications of herpes zoster caused by the reactivation of varicella-zoster virus and is characterized by severe pain. The authors previously showed the association of a human major histocompatibility complex (MHC) haplotype with postherpetic neuralgia. This study was performed to experimentally confirm the role of MHC haplotype in the development of postherpetic pain using a mouse model of postherpetic pain, which corresponds to postherpetic neuralgia.

Methods

BALB/c mice (MHC haplotype: H-2), C57BL/6 mice (MHC haplotype: H-2), and BALB/b mice, a congenic BALB/c strain with H-2, were used. Herpes simplex virus type I was transdermally inoculated on the hind paw. Unilaterally zosteriform skin lesion and pain-related responses (acute herpetic pain) were caused, and some mice showed pain-related responses (postherpetic pain) after the cure of skin lesions. Herpes simplex virus type I antigen and CD3-positive cells were immunostained in the dorsal root ganglion in the acute phase.

Results

The incidence (78%) of postherpetic pain in C57BL/6 mice was significantly higher than that (35%) in BALB/c mice (P = 0.004, odds ratio = 6.7). Furthermore, the incidence of postherpetic pain in BALB/b (H-2) was similar to that in C57BL/6. Herpes simplex virus type I antigen-positive cells were less in the dorsal root ganglion of C57BL/6 mice than that of BALB/c mice. CD3-positive T cells were more in the dorsal root ganglion of C57BL/6 mice than BALB/c mice.

Conclusions

These results suggest that the MHC haplotype (H-2) is involved in the incidence of postherpetic pain, and CD3-positive T cells may play a role in its pathogenesis.
Impact of Hypothermia on the Response to Neuromuscular Blocking Drugs
Authors: Heier Tom , Caldwell James E. , Warltier David C.
Published: April 2006

Muscle strength is reduced during hypothermia, both in the presence and in the absence of neuromuscular blocking drugs. A 2 degrees C reduction in body temperature may double the duration of neuromuscular blockade. Central body and muscle temperatures decline in parallel, as long as peripheral vasoconstriction does not occur. A reduction in muscle strength must be expected at a body temperature less than 36 degrees C (corresponding to a muscle temperature of approximately 35 degrees C). Local cooling of the hand may make adductor pollicis twitch tension monitoring less useful during clinical anesthesia. The efficacy of neostigmine is maintained during mild hypothermia. The use of a nerve stimulator is strongly recommended to monitor the effect of neuromuscular blocking drugs during intraoperative hypothermia.
In Vitro Activities of DX-619 and Four Comparator Agents against 376 Anaerobic Bacterial Isolates
Authors: Molitoris D. , Väisänen M.-L. , Bolaños M. , Finegold S. M.
Published: April 2006

The activity of DX-619 was evaluated against 376 anaerobic isolates using the reference CLSI agar dilution method. Overall, 90% of the strains were susceptible to DX-619 at ≤1 μg/ml. It was more active than the other four compounds tested except for meropenem, which showed virtually identical overall activity.
Tax Interacts with P-TEFb in a Novel Manner To Stimulate Human T-Lymphotropic Virus Type 1 Transcription
Authors: Zhou Meisheng , Lu Hanxin , Park Hyeon , Wilson-Chiru Jaime , Linton Rebecca , Brady John N.
Published: April 2006

Human T-lymphotropic virus type 1 (HTLV-1) encodes a transcriptional activator, Tax, whose function is essential for viral transcription and replication. Tax transactivates the viral long-terminal repeat through a series of protein-protein interactions which facilitate CREB and CBP/p300 binding. In addition, Tax dissociates transcription repressor histone deacetylase 1 interaction with the CREB response element. The subsequent events through which Tax interacts and communicates with RNA polymerase II and cyclin-dependent kinases (CDKs) are not clearly understood. Here we present evidence that Tax recruits positive transcription elongation factor b (P-TEFb) (CDK9/cyclin T1) to the viral promoter. This recruitment likely involves protein-protein interactions since Tax associates with P-TEFb in vitro as demonstrated by glutathione
S
-transferase fusion protein pull-down assays and in vivo as shown by coimmunoprecipitation assays. Functionally, small interfering RNA directed toward CDK9 inhibited Tax transactivation in transient assays. Consistent with these findings, the depletion of CDK9 from nuclear extracts inhibited Tax transactivation in vitro. Reconstitution of the reaction with wild-type P-TEFb, but not a kinase-dead mutant, recovered HTLV-1 transcription. Moreover, the addition of the CDK9 inhibitor flavopiridol blocked Tax transactivation in vitro and in vivo. Interestingly, we found that Tax regulates CDK9 kinase activity through a novel autophosphorylation pathway.
Dynamic Localization of the Human Papillomavirus Type 11 Origin Binding Protein E2 through Mitosis While in Association with the Spindle Apparatus
Authors: Dao Luan D. , Duffy Aaron , Van Tine Brian A. , Wu Shwu-Yuan , Chiang Cheng-Ming , Broker Thomas R. , Chow Louise T.
Published: April 2006

Papillomaviral DNA replicates as extrachromosomal plasmids in squamous epithelium. Viral DNA must segregate equitably into daughter cells to persist in dividing basal/parabasal cells. We have previously reported that the viral origin binding protein E2 of human papillomavirus types 11 (HPV-11), 16, and 18 colocalized with the mitotic spindles. In this study, we show the localization of the HPV-11 E2 protein to be dynamic. It colocalized with the mitotic spindles during prophase and metaphase. At anaphase, it began to migrate to the central spindle microtubules, where it remained through telophase and cytokinesis. It was additionally observed in the midbody at cytokinesis. A peptide spanning residues 285 to 308 in the carboxyl-terminal domain of HPV-11 E2 (E2C) is necessary and sufficient to confer localization on the mitotic spindles. This region is conserved in HPV-11, -16, and -18 and bovine papillomavirus type 4 (BPV-4) E2 and is also required for the respective E2C to colocalize with the mitotic spindles. The E2 protein of bovine papillomavirus type 1 is tethered to the mitotic chromosomes via the cellular protein Brd4. However, the HPV-11 E2 protein did not associate with Brd4 during mitosis. Lastly, a chimeric BPV-1 E2C containing the spindle localization domain from HPV-11 E2C gained the ability to localize to the mitotic spindles, whereas the reciprocal chimera lost the ability. We conclude that this region of HPV E2C is critical for localization with the mitotic apparatus, enabling the HPV DNA to sustain persistent infections.
Epigenetic Regulation of Varicella-Zoster Virus Open Reading Frames 62 and 63 in Latently Infected Human Trigeminal Ganglia
Authors: Gary Lee , Gilden Donald H. , Cohrs Randall J.
Published: April 2006

Open reading frames (ORFs) 21, 29, 62, 63, and 66 of varicella-zoster virus (VZV) are transcribed during latency in human ganglia. ORF 63 is the most frequently expressed gene, and ORF 62 encodes a transcriptional activator. The mechanisms regulating the expression of these genes are not well understood, although analyses of other alphaherpesviruses indicate a role for chromatin in virus gene regulation during latent infection. Using chromatin immunoprecipitation (ChIP) assays to analyze the euchromatic state of ORFs 62 and 63 compared to the centromere from human chromosome 4 (heterochromatic) and the human glyceraldehyde-3-phosphate dehydrogenase promoter (euchromatic), we show that the promoters of ORFs 62 and 63 are associated with the histone protein H3K9(Ac) and thus maintained in a euchromatic state during latency. Conversely, the promoters of ORF 36 (thymidine kinase) and ORF 14 (glycoprotein C), genes expressed during lytic but not latent infection, were not enriched in the fraction of latently infected ganglia that bound to anti-H3K9(Ac) antibody. A ChIP assay using productively infected MeWo cells revealed that VZV ORFs 62, 63, 36, and 14 are all euchromatic. Together, these data indicate that the expression of the two latency-related VZV genes, ORFs 62 and 63, is regulated epigenetically through chromatin structure.
Mice Develop Effective but Delayed Protective Immune Responses When Immunized as Neonates either Intranasally with Nonliving VP6/LT(R192G) or Orally with Live Rhesus Rotavirus Vaccine Candidates
Authors: VanCott John L. , Prada Anne E. , McNeal Monica M. , Stone Susan C. , Basu Mitali , Huffer Bert , Smiley Kristi L. , Shao Mingyuan , Bean Judy A. , Clements John D. , Choi Anthony H.-C. , Ward Richard L.
Published: April 2006

Rotavirus vaccines are delivered early in life, when the immune system is immature. To determine the effects of immaturity on responses to candidate vaccines, neonatal (7 days old) and adult mice were immunized with single doses of eitherEscherichia coli-expressed rotavirus VP6 protein and the adjuvant LT(R192G) or live rhesus rotavirus (RRV), and protection against fecal rotavirus shedding following challenge with the murine rotavirus strain EDIM was determined. Neonatal mice immunized intranasally with VP6/LT(R192G) were unprotected at 10 days postimmunization (dpi) and had no detectable rotavirus B-cell (antibody) or CD4+CD8+T-cell (rotavirus-inducible, Th1 [gamma interferon and interleukin-2 {IL-2}]-, Th2 [IL-5 and IL-4]-, or ThIL-17 [IL-17]-producing spleen cells) responses. However, by 28 and 42 dpi, these mice were significantly (P ≥ 0.003) protected and contained memory rotavirus-specific T cells but produced no rotavirus antibody. In contrast, adult mice were nearly fully protected by 10 dpi and contained both rotavirus immunoglobulin G and memory T cells. Neonates immunized orally with RRV were also less protected (P= 0.01) than adult mice by 10 dpi and produced correspondingly less rotavirus antibody. Both groups contained few rotavirus-specific memory T cells. Protection levels by 28 dpi for neonates or adults were equal, as were rotavirus antibody levels. This report introduces a neonatal mouse model for active protection studies with rotavirus vaccines. It indicates that, with time, neonatal mice develop full protection after intranasal immunization with VP6/LT(R192G) or oral immunization with a live heterologous rotavirus and supports reports that protection depends on CD4+T cells or antibody, respectively.
THE LONG-TERM OPTICAL VARIABILITY PROPERTIES OF GAMMA-RAY BLAZAR 3C 273
Authors: DAI BEN-ZHONG , ZHANG BIN-KAI , XIANG YANG , YANG JIAN-PING , LIN LIN , XU LI , DAI HONG , ZHANG LI
Published: April 2006

We compile all the available optical B band data for the quasar 3C 273 from 1887 to 2001 from the literature, and obtain 1,890 data points. Using these data, we analyze the light curve properties by means of the Jurkevich method and the discrete correlation function (DCF) method. The analysis results of the two methods are self consistent; the cross-checked variability period is 13.51 years. The 13.51-year period variation in the optical band is in good agreement with the previous results in the optical and X-ray bands. However, the other claimed periods of the quasar 3C 273 are not confirmed in our work.