bluuebunny/crossref_metadata_2025 huggingface dataset:
Neo-liberal economic practices and population health: a cross-national analysis, 1980–2004
Authors: Tracy Melissa , Kruk Margaret E. , Harper Christine , Galea Sandro
Published: September 2009

Although there has been substantial debate and research concerning the economic impact of neo-liberal practices, there is a paucity of research about the potential relation between neo-liberal economic practices and population health. We assessed the extent to which neo-liberal policies and practices are associated with population health at the national level. We collected data on 119 countries between 1980 and 2004. We measured neo-liberalism using the Fraser Institute’s Economic Freedom of the World (EFW) Index, which gives an overall score as well as a score for each of five different aspects of neo-liberal economic practices: (1) size of government, (2) legal structure and security of property rights, (3) access to sound money, (4) freedom to exchange with foreigners and (5) regulation of credit, labor and business. Our measure of population health was under-five mortality. We controlled for potential mediators (income distribution, social capital and openness of political institutions) and confounders (female literacy, total population, rural population, fertility, gross domestic product per capita and time period). In longitudinal multivariable analyses, we found that the EFW index did not have an effect on child mortality but that two of its components: improved security of property rights and access to sound money were associated with lower under-five mortality (p = 0.017 and p = 0.024, respectively). When stratifying the countries by level of income, less regulation of credit, labor and business was associated with lower under-five mortality in high-income countries (p = 0.001). None of the EFW components were significantly associated with under-five mortality in low-income countries. This analysis suggests that the concept of ‘neo-liberalism’ is not a monolithic entity in its relation to health and that some ‘neo-liberal’ policies are consistent with improved population health. Further work is needed to corroborate or refute these findings.
Nichtinvasive Beatmung
Authors: Dodt Christoph
Published: September 2009

Die Dyspnoe im Rahmen einer akuten respiratorischen Insuffizienz bedarf einer sofortigen therapeutischen Intervention. Dabei hat sich bei der hyperkapnischen Exazerbation der chronisch obstruktiven Lungenerkrankung die nichtinvasive Ventilation (NIV) im klinischen Alltag etabliert. Durch die NIV wird die Notwendigkeit für eine invasive Beatmung reduziert. Dies reduziert bei Patienten mit dieser Erkrankung die Mortalität deutlich. Bei der respiratorischen Insuffizienz im Rahmen einer akuten Linksherzinsuffizienz wird die Dyspnoe durch Atemunterstützungsverfahren rascher reduziert. Bei beiden Krankheitsbildern ist der frühzeitige Einsatz besonders günstig. Deswegen ist es sinnvoll, diese Beatmungsform auch in Notaufnahmen zu etablieren.
Stellenwert der Lungenfunktion in der Abklärung der Atemnot
Authors: Leuppi Jörg D.
Published: September 2009

Die Abklärung der Atemnot kann auch für erfahrene Ärzte eine Herausforderung sein. In bis zu einem Drittel der Fälle ist die Atemnot durch verschiedene Ursachen gleichzeitig bedingt. Da mit alleiniger Anamnese oder klinischer Untersuchung z. B. eine Atemwegsobstruktion verpasst wie auch überschätzt werden kann, ist die Spirometrie im Abklärungsbaum der Dyspnoe ein wichtiger Untersuchungsschritt. Damit die Spirometrie ein hilfreiches Instrument im Abklärungsbaum der Atemnot sein kann, ist eine aussagekräftige und somit qualitativ hochstehende Untersuchung notwendig. Werden entsprechende Qualitätskriterien berücksichtigt, kann aber mit dieser einfachen und billigen Untersuchung ein nützlicher Baustein in der Abklärung der Atemnot gelegt werden.
Stellenwert der Spiroergometrie in der Diagnostik der Belastungsdyspnoe
Authors: Maeder Micha T.
Published: September 2009

Die Spiroergometrie (cardiopulmonary exercise testing, CPET) ist der Goldstandard zur Abklärung der unklaren Belastungsdyspnoe. Während Untersuchungen einzelner Organsysteme in Ruhe die Reaktion unter Belastung nicht verlässlich vorhersagen können, ermöglicht CPET eine integrative Beurteilung der Belastungsantwort, welche ein komplexes Zusammenspiel verschiedener Organsysteme (kardial, pulmonal, Arbeitsmuskulatur, Sauerstofftransportkapazität, Koordination etc.) darstellt. Die Stärke der Untersuchung beruht auf der exakten Quantifizierung der Leistungsfähigkeit mittels maximaler Sauerstoffaufnahme, Beurteilbarkeit des Efforts und der Möglichkeit, die der Leistungsintoleranz hauptsächlich zugrunde liegenden Faktoren zu identifizieren.
Model simulations of the Bay of Fundy Gyre: 2. Hindcasts for 2005–2007 reveal interannual variability in retentiveness
Authors: Aretxabaleta Alfredo L. , McGillicuddy Dennis J. , Smith Keston W. , Manning James P. , Lynch Daniel R.
Published: September 2009

A persistent gyre at the mouth of the Bay of Fundy results from a combination of tidal rectification and buoyancy forcing. Here we assess recent interannual variability in the strength of the gyre using data assimilative model simulations. Realistic hindcast representations of the gyre are considered during cruises in 2005, 2006, and 2007. Assimilation of shipboard and moored acoustic Doppler current profiler velocities is used to improve the skill of the simulations, as quantified by comparison with nonassimilated drifter trajectories. Our hindcasts suggest a weakening of the gyre system during May 2005. Retention of simulated passive particles in the gyre during that period was highly reduced. A recovery of the dense water pool in the deep part of the basin by June 2006 resulted in a return to particle retention characteristics similar to climatology. Retention estimates reached a maximum during May 2007 (subsurface) and June–July 2007 (near surface). Interannual variability in the strength of the gyre was primarily modulated by the stratification of the dense water pool inside the Grand Manan Basin. These changes in stratification were associated with mixing conditions the preceding fall–winter and/or advectively driven modification of water mass properties.
Green's function of a parallel plate waveguide with multiple abrupt changes of interwall distances
Authors: Valagiannopoulos Constantine A. , Uzunoglu Nikolaos K.
Published: September 2009

The Green's function of a parallel plate waveguide with cascaded step discontinuities is computed by using analytical methods. The expression is written as a sum of two terms, the first of which corresponds to the effect of the horizontal plates on the primary source's field taking into account the symmetric images with respect to the metallic boundaries. The second term is related to the reflections from the vertical discontinuity edges, which are treated by applying successively a mode‐matching technique. The solution of the posed boundary value problem is obtained through a well‐conditioned linear system. The behavior of the guided waves far from the discontinuity region is determined with the help of far field approximations. Numerical computations for specific cases are presented and examined and many general purpose procedures of educational and tutorial interest are extensively described.
Relationships among groundwater age, denitrification, and the coupled groundwater and nitrogen fluxes through a streambed
Authors: Kennedy Casey D. , Genereux David P. , Corbett D. Reide , Mitasova Helena
Published: September 2009

The relationships among coupled groundwater and nitrogen (N) fluxes, groundwater age, and denitrification were examined for a section of West Bear Creek, an agricultural stream in the coastal plain of North Carolina, United States. Simultaneous streambed measurements of hydraulic conductivity (K) and hydraulic head gradient (J) and the concentrations of NO3− ([NO3−]), dissolved gases, and chlorofluorocarbons in groundwater were interpolated, mapped, and (for water flux v = KJ and nitrate flux fNO3 = v[NO3−]) integrated over the streambed area. Nitrate and dissolved organic N accounted for 92 and 8% of N flux through the streambed, respectively. Streambed maps show a band of greater groundwater age, and lower [NO3−] and fNO3, running through the center of most of the study reach. Nitrate flux (fNO3) exhibits this “center‐low” pattern even though one of its controlling factors, groundwater flux (v), has on average the opposite “center‐high” pattern. An inverse relationship between [NO3−] and age is indicative of fertilizer as the primary source of groundwater NO3−. Denitrification reduced mean fNO3 by ∼50%, from 370 mmol m−2 d−1 (what it would have been in the absence of denitrification) to 173 mmol m−2 d−1 (what it actually was). Measurement of both groundwater age and v made possible a new method for estimating flow‐weighted mean groundwater age (τFWM), an important aquifer hydraulic characteristic related to groundwater storage and recharge rate. This method gives τFWM = 30 years, which, along with the overall distribution of groundwater ages, suggests the possibility of a significant time lag between changes in N fertilizer application rates and NO3− flux from groundwater to West Bear Creek. Differences in streambed groundwater chemistry between the left and right sides of the streambed suggest differences in agricultural practices on opposite sides of the stream.
Online Tools Help Get Scientists and Educators on the Same Page
Authors: DeCharon Annette , Albright Jennifer , Herren Christy , Cline Amy H. , Repa J. Theodore
Published: September 2009

As part of its effort to foster substantive dialogue between scientists and educators, the Centers for Ocean Sciences Education Excellence—Ocean Systems (COSEE‐OS), a center in the COSEE network, has developed an applied concept‐mapping process and a related suite of interactive multimedia tools that focus on ocean and climate concepts. The resulting maps illustrate connections among concepts related to ocean and climate science. These tools, developed over the past 3 years, help scientists see and graphically display relationships among the concepts in their field, and help them communicate those concepts clearly and logically to educators and other scientists.

COSEE‐OS research has indicated that concept mapping benefits scientists by identifying what they do and do not explain well to educators. Evaluation studies conducted by COSEE‐OS external evaluator Ted Repa include interviews with scientists and survey responses of the educators who participate in COSEE‐OS workshops. By continuously improving its workshop design and suite of interactive communication tools, COSEE‐OS strives to increase the levels of collaboration between scientists and educators by fostering peer‐to‐peer learning environments.
Scalable robust solvers for unstructured FE geodynamic modeling applications: Solving the Stokes equation for models with large localized viscosity contrasts
Authors: Geenen T. , ur Rehman M. , MacLachlan S. P. , Segal G. , Vuik C. , van den Berg A. P. , Spakman W.
Published: September 2009

The development of scalable robust solvers for unstructured finite element applications related to viscous flow problems in earth sciences is an active research area. Solving high‐resolution convection problems with order of magnitude 108 degrees of freedom requires solvers that scale well, with respect to both the number of degrees of freedom as well as having optimal parallel scaling characteristics on computer clusters. We investigate the use of a smoothed aggregation (SA) algebraic multigrid (AMG)‐type solution strategy to construct efficient preconditioners for the Stokes equation. We integrate AMG in our solver scheme as a preconditioner to the conjugate gradient method (CG) used during the construction of a block triangular preconditioner (BTR) to the Stokes equation, accelerating the convergence rate of the generalized conjugate residual method (GCR). We abbreviate this procedure as BTA‐GCR. For our experiments, we use unstructured grids with quadratic finite elements, making the model flexible with respect to geometry and topology and O(h3) accurate. We find that AMG‐type methods scale linearly (O(n)), with respect to the number of degrees of freedom, n. Although not all parts of AMG have preferred parallel scaling characteristics, we show that it is possible to tune AMG, resulting in parallel scaling characteristics that we consider optimal, for our experiments with up to 100 million degrees of freedom. Furthermore, AMG‐type methods are shown to be robust methods, allowing us to solve very ill‐conditioned systems resulting from strongly varying material properties over short distances in the model interior.
Ultrastructure of medullary thymic epithelial cells of autoimmune regulator (Aire)‐deficient mice
Authors: Milićević Živana , Milićević Novica M , Laan Martti , Peterson Pärt , Kisand Kai , Scott Hamish S , Westermann Jürgen
Published: September 2009

The significance of the autoimmune regulator (Aire) transcription regulator in establishing central tolerance has recently been elucidated in great detail. Still, the role of Aire in medullary thymic epithelial cell (mTEC) physiology is not fully understood. To shed more light on this issue, we studied the ultrastructure of mTECs in Aire‐deficient thymus. We show that all types of mTECs show ultrastructural signs of activation and increased intracellular traffic, which suggests that in the absence of Aire their physiology is impaired. Type 6 ‘large’ mTECs are fully developed in Aire‐deficient mice and more frequent than in the normal thymus. The frequency of type 5 ‘undifferentiated’ mTECs is also increased. Collectively, our results suggest that the role of Aire in the physiology of mTECs could be more profound and not restricted only to the presentation of self‐tissue‐restricted antigens and/or apoptosis of end‐stage fully mature cell types.
Cerebrovascular Responses to Insulin in Rats
Authors: Katakam Prasad Venkateswera Gurunath , Domoki Ferenc , Lenti Laura , Gáspár Tamás , Institoris Adam , Snipes James Andy , Busija David William
Published: September 2009

Effects of insulin on cerebral arteries have never been examined. Therefore, we determined cerebrovascular actions of insulin in rats. Both PCR and immunoblot studies identified insulin receptor expression in cerebral arteries and in cultured cerebral microvascular endothelial cells (CMVECs). Diameter measurements (% change) of isolated rat cerebral arteries showed a biphasic dose response to insulin with an initial vasoconstriction at 0.1 ng/mL (−9.7%±1.6%), followed by vasodilation at 1 to 100 ng/mL (31.9%±1.4%). Insulin also increased cortical blood flow in vivo (30%±8% at 120 ng/mL) when applied topically. Removal of reactive oxygen species (ROS) abolished the vasoconstriction to insulin. Endothelial denudation, inhibition of K+ channels, and nitric oxide (NO) synthase, all diminished insulin-induced vasodilation. Inhibition of cytochrome P450 enhanced vasodilation in endothelium-intact arteries, but promoted vasoconstriction after endothelial denudation. Inhibition of cyclooxygenase abolished vasoconstriction and enhanced vasodilation to insulin in all arteries. Inhibition of endothelin type A receptors enhanced vasodilation, whereas endothelin type B receptor blockade diminished vasodilation. Insulin treatment in vitro increased Akt phosphorylation in cerebral arteries and CMVECs. Fluorescence studies of CMVECs showed that insulin increased intracellular calcium and enhanced the generation of NO and ROS. Thus, cerebrovascular responses to insulin were mediated by complex mechanisms originating in both the endothelium and smooth muscle.
Brain and Blood microRNA Expression Profiling of Ischemic Stroke, Intracerebral Hemorrhage, and Kainate Seizures
Authors: Liu Da-Zhi , Tian Yingfang , Ander Bradley P , Xu Huichun , Stamova Boryana S , Zhan Xinhua , Turner Renee J , Jickling Glen , Sharp Frank R
Published: September 2009

MicroRNAs (miRNAs) regulate gene expression and have a critical role in many biologic and pathologic processes. We hypothesized that miRNA expression profiles in injured brain (hippocampus) would show common as well as unique profiles when compared with those of blood. Adult, untouched, control rats were compared with rats with sham surgeries, ischemic strokes, brain hemorrhage (lysed blood, fresh blood, or thrombin), and kainate-induced seizures. Brain and whole-blood miRNA expression profiles were assessed 24 h later using TaqMan rodent miRNA arrays. MicroRNA response profiles were different for each condition. Many miRNAs changed more than 1.5-fold in brain and blood after each experimental manipulation, and several miRNAs were upregulated or downregulated in both brain and blood after a given injury. A few miRNAs (e.g., miR-298, miR-155, and miR-362-3p) were upregulated or downregulated more than twofold in both brain and blood after several different injuries. The results show the possible use of blood miRNAs as biomarkers for brain injury; that selected blood miRNAs may correlate with miRNA changes in the brain; and that many of the mRNAs, previously shown to be regulated in brain and blood after brain injury, are likely accounted for by changes in miRNA expression.
Treatment of Stroke with a Synthetic Liver X Receptor Agonist, TO901317, Promotes Synaptic Plasticity and Axonal Regeneration in Mice
Authors: Chen Jieli , Zacharek Alex , Cui Xu , Shehadah Amjad , Jiang Hao , Roberts Cynthia , Lu Mei , Chopp Michael
Published: September 2009

In this study, we tested the hypothesis that TO901317 promotes synapse plasticity and axonal regeneration after stroke. Adult male C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAo) and treated with or without TO901317 starting 24 h after MCAo daily for 14 days. Axonal damage and regeneration were evaluated by immunostaining. TO901317 significantly increased synaptophysin expression and axonal regeneration, as well as decreased the expressions of amyloid betaA4 precursor protein and Nogo receptor (NgR) in the ischemic brain. To test whether TO901317 regulates the phosphorylation of phosphatidylinositol 3-kinase (p-PI3K) and Akt (p-Akt) activity in the ischemic brain, MCAo mice were treated with or without TO901317 starting 24 h after MCAo daily for 4 days and were then killed at 5 days after MCAo. TO901317 treatment significantly increased p-PI3K and p-Akt activity, but did not increase total PI3K expression in the ischemic brain. Using primary cortical neuron (PCN) culture, TO901317 significantly increased synaptophysin expression, p-PI3K activity, and decreased NgR expression compared with nontreated controls. TO901317 also significantly increased neurite outgrowth, and inhibition of the PI3K/Akt pathway by LY294002 decreased neurite outgrowth in both controls and TO901317-treated groups in cultured hypoxic PCN. These data indicate that TO901317 promotes synaptic plasticity and axonal regeneration, and that PI3K/Akt signaling activity contributes to neurite outgrowth.
Innovation in cardiology. A new diagnostic standard establishing criteria of quantitative & qualitative evaluation of main parameters of the cardiac & cardiovascular system according to ECG and Rheo based on cardiac cycle phase analysis
Authors: Mamberger K , Makedonsky D , Rudenko M , Kolmakov S , Weber Konstantine , Voronova O , Zernov V , Rudenko S
Published: September 2009

Over more than 50 years the theory of functioning of the cardiac & cardiovascular system remained unchanged. As a rule, all conventional diagnostics methods are based on statistics data on changes in shapes of cardiac signals only, so that it is impossible to determine the relevant cause-effect relations with respect to their formation [1,2]. But a theory of elevated fluidity of liquid offered twenty five years ago makes it possible to develop an innovative method of the phase analysis of the cardiac cycle [3]. The successful application of the said method in researches for the last 5 years has enabled a practical implementation of an indirect measuring concept with respect to volumetric hemodynamic parameters [4]. By evaluating hemodynamic parameters upon examination of more than 3000 patients the Authors have identified the actual cause-effect relations in formation of the respective ECG & Rheo so that new capabilities are being offered in cardiology. This article should be treated as a logic result reflecting a long-term experience accumulated in large-scale investigations covering the complete cardiac & cardiovascular system operation.
Quantum stochasticity and neuronal computations
Authors: Jedlicka Peter
Published: September 2009

The nervous system probably cannot display macroscopic quantum (i.e. classically impossible) behaviours such as quantum entanglement, superposition or tunnelling (Koch and Hepp, Nature 440:611, 2006). However, in contrast to this quantum ‘mysticism’ there is an alternative way in which quantum events might influence the brain activity. The nervous system is a nonlinear system with many feedback loops at every level of its structural hierarchy. A conventional wisdom is that in macroscopic objects the quantum fluctuations are self-averaging and thus not important. Nevertheless this intuition might be misleading in the case of nonlinear complex systems. Because of a high sensitivity to initial conditions, in chaotic systems the microscopic fluctuations may be amplified upward and thereby affect the system's output. In this way stochastic quantum dynamics might sometimes alter the outcome of neuronal computations, not by generating classically impossible solutions, but by influencing the selection of many possible solutions (Satinover, Quantum Brain, Wiley & Sons, 2001). I am going to discuss recent theoretical proposals and experimental findings in quantum mechanics, complexity theory and computational neuroscience suggesting that biological evolution is able to take advantage of quantum-computational speed-up. I predict that the future research on quantum complex systems will provide us with novel interesting insights that might be relevant also for neurobiology and neurophilosophy.
The effect of drought and subsequent precipitation pulse on productivity, species composition, and carbon fluxes of the herbaceous understorey in a cork oak woodland
Authors: Jongen Marjan , Caldeira Maria C. , Pereira João S.
Published: September 2009

In the Iberian Peninsula, the cork oak woodlands are of great ecological and socio-economic importance. These savanna-type woodlands are characterized by an herbaceous understorey, dominated by C3 annual species. The productivity and related ecosystem processes of this understorey are highly dependent on timing and magnitude of precipitation events. Climate change scenarios for the Iberian Peninsula suggest not only increasing air temperatures, but also the possibility of decreasing spring precipitation, accompanied by an increase in the interval between precipitation events, which might cause drought conditions to occur, with more severe effects on productivity and ecosystem processes. An experiment was carried out in southern Portugal to assess the effect of a drought treatment, with a subsequent extreme precipitation event, on the herbaceous component of managed cork oak woodland. The facility consisted of five plots with rainout shelters (2.5 x 2.5 m), which exclude normal rainfall inputs (drought treatment), and five non-sheltered control plots (control treatment). In the drought treatment, 193 mm of precipitation was excluded in the period from mid March to mid May, with a subsequent precipitation pulse of 50 mm in the middle of May. Variables measured included productivity, plant community composition, soil respiration and soil microbial activity.
Magnetoresistance of TVO temperature sensor at T<1 K
Authors: Filippov Yu. P. , Ihas G. G. , Vainberg V. V.
Published: September 2009

A magnetoresistance (MR) of the well known TVO resistor temperature sensors has been studied at ultralow temperatures from ≈0.8 K down to ≈0.1 K under strong magnetic fields up to 8 T. A crossover from positive to negative MR with lowering temperature is found at weak magnetic fields. A zero MR-value at the magnetic field of 4 T, for example, is reached at T≈0.2 K. At sufficiently strong magnetic field the negative MR is suppressed and MR returns to positive values. A constant negative MR, which does not depend on the magnetic field from 2 to 8 T, is revealed at the lowest temperature T≈0.1 K. The observed behavior of the TVO sensor is explained basing on the model of hopping conduction via localized states in the weak localization regime.
Experiments on rapidly rotating turbulent flows
Authors: van Bokhoven L. J. A. , Clercx H. J. H. , van Heijst G. J. F. , Trieling R. R.
Published: September 2009

A novel laboratory experiment for investigating statistically steady rotating turbulence is presented. Turbulence is produced nonintrusively by means of electromagnetic forcing. Depending on the rotation rate the Taylor-based Reynolds number is found to be in the range of 90≲Reλ≲240. Relevant properties of the turbulence, both with and without rotation, have been quantified with stereoscopic particle image velocimetry (SPIV). This method enables instantaneous measurement of all three velocity components in horizontal planes at a distance H from the bottom. The root-mean-square turbulent velocity decreases inversely proportional to H in the nonrotating experiments and is approximately constant when background rotation is applied. The integral length scale shows a weak H-dependence in the nonrotating experiments which is presumably due to the spatial extent of the forcing. Based on the behavior of the principal invariants of the Reynolds stress anisotropy tensor, the rotating turbulence has been characterized as a three-dimensional two-component flow. Furthermore, these SPIV measurements provide supporting evidence for (i) reduction of the dissipation rate, (ii) suppression of the vertical velocity as compared to the horizontal velocity, and (iii) increased spatial and temporal correlation of the horizontal velocity components, with the temporal correlation growing ever stronger as the rotation rate is increased. A less commonly known feature of rotating turbulence, quantified here for the first time in a laboratory setting, is the reverse dependence on the rotation rate of the spatial horizontal velocity correlation functions. Another interesting result concerns the linear (anomalous) scaling of the longitudinal spatial structure function exponents in the presence of rotation, consistent with a study by Baroud et al. [Phys. Rev. Lett. 88, 114501 (2002)].
Low-temperature grown near surface semiconductor saturable absorber mirror: Design, growth conditions, characterization, and mode-locked operation
Authors: Jasik A. , Muszalski J. , Pierściński K. , Bugajski M. , Talalaev V. G. , Kosmala M.
Published: September 2009

We have developed a mode-locked diode-pumped Yb:KY(WO4)2 laser generating nearly bandwidth limited pulses as short as 101 fs. At 1.1 W of absorbed power and for 3% transmission output coupler, the laser delivers 150 mW in pulses of 110 fs duration, which corresponds to the efficiency of 14%. This has been achieved using semiconductor saturable absorber mirror (SESAM) grown by molecular beam epitaxy. The low-temperature (LT) absorbers were crystallized under the carefully optimized growth conditions. The resonantlike type structures ensured relatively high enhancement factor and in consequence high absorption modulation. The main device parameters such as group delay dispersion (GDD) and enhancement factor were chosen to be wavelength independent. The optimization of the growth conditions resulted in a reduction in the nonsaturable absorption in as-grown LT-InGaAs absorbing layer and ensured the fast carrier trapping and recombination. We assume that the nonsaturable losses of the annealed LT layers result from the absorption connected with defects generated in the crystal during LT growth. Moreover, the annealing deteriorates the interface sharpness and the crystal quality of LT pseudomorphic, nonstoichiometric InGaAs layer. On the other hand, higher growth temperature and lower ratio of group V to group III beam equivalent pressure (V/III ratio) ensure lower defect densities and high crystal quality but suffer from the absorption related to AsGa0 conduction band transitions. The careful balancing of these contradictory tendencies allowed for optimization of the absorber properties. The InGaAs quantum well absorbing layer was grown at the temperature as high as 420 °C, under the V/III ratio as low as 10. No postgrowth annealing was performed. The recovery time of the SESAM structure characterized by the pump-probe measurements was equal to 9.6 ps. The nonsaturable losses of 1.94% decreased the modulation depth to 1.48% but still self-starting and stable mode locking was observed. The saturation fluence of 27 μJ/cm2 did not suffer significantly from a little bit too high nonsaturable losses.
Addressing the plasma formation on the surface of a ferroelectric sample
Authors: Gurovich V. Tz. , Krasik Ya. E. , Raichlin V. , Felsteiner J. , Haber I.
Published: September 2009

A description of plasma formation on the surface of a ferroelectric sample is presented, based on simple assumptions about the electrodynamic evolution of the system along with the continuity equation for the current and the conservation of the ion flow impulse. Two models starting with these assumptions are shown capable of predicting, with satisfactory agreement to experimental data, the plasma density and temperature, and plasma propagation velocity. Also, one of the models allows one to obtain the distributions of the potential, surface charge density, and current density along the ferroelectric surface during plasma propagation.
Photonic energy band structure of excitonic quantum dot dimer system
Authors: Fu Y.
Published: September 2009

We study the energy dispersion of a photonic crystal composed of two types of excitonic quantum dots (QD dimer system), type-I QDs at their ground states while type-II QDs are already excited. The excitation and de-excitation of the exciton states in the QDs by an external electromagnetic field contribute extra dielectric polarizations with respect to the background material, thus a contrast in the dielectric constant and the eventual formation of the photonic dispersion. By assuming periodic boundary conditions, it has been shown that the photonic dispersion of the QD dimer system is composed of modified but still characteristic dispersions of the two types of QDs in their separate photonic crystal formats. Starting from the transparent condition of type-II QDs, the photonic structure of the QD dimer system evolves from the one of type-I QDs to the composite dimer system. The modification due to the radiative interaction between the two types of the QDs is symmetric with respect to the change in the excitation degree of type-II QDs (increase/decrease the excitation degree from transparent status so that type-II QDs become optically gain/lossy). It is thus concluded that the transport of an external electromagnetic field is normal in the QD dimer system and achieving a lossless negative-dielectric material at a single frequency is possible by using the QD dimer system.
Extraordinary magnetic field induced suppression of luminescence in Er3+-doped nano-glass-ceramics
Authors: Chibotaru L. F. , Tikhomirov V. K. , Saurel D. , Moshchalkov V. V.
Published: September 2009

The effect of magnetic field on luminescence intensity is generally expected to be rather weak. Contrary to this expectation, we report here an extraordinary strong intensity suppression (by two orders of magnitude) of the Er3+ S43/2→I415/2 green emission line in Er3+-doped nano-glass-ceramics by applying magnetic field up to 50 T. We argue that this effect arises from different site geometries and, consequently, strongly differing Judd–Ofelt intensities of transitions for the two Kramers doublets of the emitting S43/2 multiplet.
The orientation dependent electromigration induced healing on the surface cracks and roughness caused by the uniaxial compressive stresses in single crystal metallic thin films
Authors: Ogurtani Tarik Omer
Published: September 2009

The first order unified linear instability analysis (ULISA) of the governing equation for evolutions of surfaces and interfaces under the capillary, electromigration, and elastostatic forces including the thermomigration (Soret effect) is developed very recently by the author. In the present application of the theory, the concurrent effects of uniaxial applied stresses and the electrostatic field on the sidewall morphological evolution of a single crystal thin metallic film are explored by dynamic computer simulations by taking the surface drift diffusion anisotropy fully into account. These computer experiments, which are supported by ULISA, clearly show that only the applied elastic compressive stresses are primary agents responsible for the morphological instability of the surface undulations through the elastic dipole tensor interactions but not the uniaxial tension loading in thin solid films. It is also demonstrated that these morphological instabilities manifested themselves as formations of the surface cracks and thus one may fully control the roughness. To do that, one needs to select crystal orientations properly with respect to the applied field so that a counteraction of the applied electrostatic fields (healing effect) is created above well defined threshold levels of electromigration. On the contrary to the healing effects, the improper selection of crystal orientations may drastically enhance the instability and eventually may cause catastrophic interconnect failure. At large normalized surface undulation amplitudes (a¯≥0.20), the drastic reductions in the decay rate constants (i.e., the strain relaxation rate) are detected in the nonlinear uniaxial tension regime compared to the ULISA theory regardless of the intensity of the normalized stress by analyzing the data obtained from the computer simulations. This situation is contrary to the results deduced from the low to moderate normalized amplitude (a¯≤0.10) measurements, where one finds that the decay rate constant closely obeys the prediction of the ULISA theory even for very high stress intensities.
Microscopic origin of training in exchange bias system
Authors: Paul Amitesh , Mattauch Stefan
Published: September 2009

The microscopic origin of training in exchange coupled systems has been identified from our experimentally observed microscopic suppression of training. It is an interplay of uniaxial anisotropy and uncompensated spins in the antiferromagnet grains that are rotatable in polycrystalline antiferromagnetic layer similar to spin-glass-like behavior.
A study on the temperature dependence of characteristics of phase change memory devices
Authors: Lee Suyoun , Jeong Doo Seok , Jeong Jeung-hyun , Zhe Wu , Park Young-Wook , Ahn Hyung-Woo , Kim Won Mok , Cheong Byung-ki
Published: September 2009

We investigated the temperature dependence of characteristics of phase change memory devices composed of Ge2Sb2Te5 (GST). We found that the RESET resistance (RR), SET resistance (RS), and SET time (tSET) decreased with increasing ambient temperature (Tamb.) while RESET current (IR) increased with Tamb. These results were explained in terms of the enhanced thermal activation of electrical conduction in GST and the increased thermal conductivity of the bottom electrode with Tamb.. Besides, threshold voltage (Vth) was found to decrease linearly with Tamb., seemingly in support of the relaxation semiconductor model and hopping-dominated transport model both of which predicted the existence of critical conductivity for threshold switching in chalcogenide glasses.
Optical line shapes of molecular aggregates: Hierarchical equations of motion method
Authors: Chen Liping , Zheng Renhui , Shi Qiang , Yan YiJing
Published: September 2009

The absorption line shapes of model molecular aggregates are investigated using the recently developed Liouville space hierarchical equations of motion (HEOM) method. The exact results are further exploited for the assessment of several approximation schemes, including the high temperature approximation of HEOM, the stochastic Liouville equation approach, and the perturbative time-local and time-nonlocal quantum master equations (QMEs). The calculations on dimers, larger ring-shaped aggregates, and a model of the B850 ring in the LH2 of purple bacteria show that while the other approximate methods can give reasonable absorption line shapes over a wide range of parameter regimes, the second-order time-nonlocal QME is generally inaccurate and may give spurious peaks in the absorption spectra.
Linear and nonlinear susceptibilities from diffusion quantum Monte Carlo: Application to periodic hydrogen chains
Authors: Umari P. , Marzari Nicola
Published: September 2009

We calculate the linear and nonlinear susceptibilities of periodic longitudinal chains of hydrogen dimers with different bond-length alternations using a diffusion quantum Monte Carlo approach. These quantities are derived from the changes in electronic polarization as a function of applied finite electric field—an approach we recently introduced and made possible by the use of a Berry-phase, many-body electric-enthalpy functional. Calculated susceptibilities and hypersusceptibilities are found to be in excellent agreement with the best estimates available from quantum chemistry—usually extrapolations to the infinite-chain limit of calculations for chains of finite length. It is found that while exchange effects dominate the proper description of the susceptibilities, second hypersusceptibilities are greatly affected by electronic correlations. We also assess how different approximations to the nodal surface of the many-body wave function affect the accuracy of the calculated susceptibilities.
Persistence length and scaling properties of single-stranded DNA adsorbed on modified graphite
Authors: Rechendorff Kristian , Witz Guillaume , Adamcik Jozef , Dietler Giovanni
Published: September 2009

We have characterized the polymer physics of single-stranded DNA (ssDNA) using atomic force microscopy. The persistence length ℓp of circular ssDNA adsorbed on a modified graphite surface was determined independently of secondary structure. At a very low ionic strength we obtained ℓp=9.1 nm from the bond correlation function. Increasing the salt concentration lead to a decrease in ℓp; at 1 mM NaCl we found ℓp=6.7 nm, while at 10 mM NaCl a value ℓp=4.6 nm was obtained. The persistence length was also extracted from the root-mean-square end-to-end distance and the end-to-end distance distribution function. Finally, we have investigated the scaling behavior using the two latter quantities, and found that on long length scales ssDNA behaves as a two-dimensional self-avoiding walk.
Possible origins of the magnetoresistance gain in colossal magnetoresistive oxide La0.69Ca0.31MnO3: Structure fluctuation and pinning effect on magnetic domain walls
Authors: Yu X. Z. , Li Run-Wei , Asaka T. , Ishizuka K. , Kimoto K. , Matsui Y.
Published: September 2009

The spatial fluctuation of the magnetic domain (MD) and charge/orbital ordering (CO/OO) structure at around the Curie temperature (TC) was directly observed in a colossal magnetoresistance (CMR) compound, La0.69Ca0.31MnO3, in which extraordinary anisotropic magnetoresistance (AMR) has also been observed. It was found that the long range MD structure collapses upon the emergence of short range CO/OO in a narrow temperature regime, which provides abundant evidence in support of a gain in magnetoresistance at around TC. Moreover, the pinning effect on the MD wall was discerned and it may contribute to the CMR as well as to the extraordinary AMR effect.
Vertical coupled double organic microcavities
Authors: Stelitano S. , De Luca G. , Savasta S. , Monsù Scolaro L. , Patané S.
Published: September 2009

A light emitting structure consisting of two coupled microcavities has been realized and studied. One of the two cavities contains a luminescent organic thin film of tetrakis(4-methoxyphenyl)porphyrin, whereas the other microcavity is a dielectric structure coupled to the organic one by means of a LiF/ZnS Bragg mirror. Reflectivity spectra show the presence of two well defined cavity dips. We observe an energy splitting of the two cavity modes. Despite the fact that only one cavity contains the active layer, the photoluminescence spectra display two peaks with comparable intensities at the same energy of the reflectivity dips. These observations indicate the strong coupling of the two cavities. The comparison of the diagonalized effective Hamiltonian with the observed resonances further confirms the strong coupling.
Enhancement in the field sensitivity of magnetoelectric laminate heterostructures
Authors: Das J. , Gao J. , Xing Z. , Li J. F. , Viehland D.
Published: September 2009

The effect of magnetostrictive layer thickness on the magnetoelectric (ME) response and field sensitivity of Pb(Zr,Ti)O3-metglas based sandwiched ME heterostructures has been studied. Such structures hold promise for sensor applications. The increase in metglas thickness results in a significant increase in the ME response and magnetic field sensitivity. The ME coefficient and field sensitivity increase by about 1.5–1.75 and 2.7 times, respectively, for a structure with 150 μm thick six metglas layers on both sides of the Pb(Zr,Ti)O3, in comparison to a 50 μm thick two layered structure.
Month-long calculation resolves 82-year-old quantum paradox
Authors: Day Charles
Published: September 2009

A chiral molecule’s transition from a superposition of its left-handed and right-handed isomers to the isomers themselves reveals the nature of the quantum-to-classical transition.
Hormonal anticipation of territorial challenges in cichlid fish
Authors: Antunes Raquel A. , Oliveira Rui F.
Published: September 2009

In many territorial species androgens respond to social interactions. This response has been interpreted as a mechanism for adjusting aggressive motivation to a changing social environment. Therefore, it would be adaptive to anticipate social challenges and reacting to their clues with an anticipatory androgen response to adjust agonistic motivation to an imminent social challenge. Here we test the hypothesis of an anticipatory androgen response to territorial intrusions using classical conditioning to establish an association between a conditioned stimulus (CS = light) and an unconditioned stimulus (US = intruder male) in male cichlid fish (
Oreochromis mossambicus
). During the training phase conditioned males (CS−US paired presentations) showed a higher decrease in latency for agonistic response toward the intruder than unconditioned males (CS–US unpaired presentations). In the test trial, conditioned males showed an increase in androgen levels (i.e., testosterone and 11-ketotestosterone) relative to baseline, in response to the CS alone. This increase was similar to that of control males exposed to real intruders after CS, whereas unconditioned males showed a decrease in androgen levels in response to the CS. Furthermore, conditioned males were significantly more aggressive than unconditioned males during the post-CS period on test trial, even though the intruder male was not present during this period. These results reveal the occurrence of a conditioned androgen response that may give territorial males an advantage in mounting a defense to upcoming territorial intrusions, if the ability to readily elevate androgens does not co-vary with other traits that bear costs.
Impaired respiration discloses the physiological significance of state transitions in
Chlamydomonas
Authors: Cardol Pierre , Alric Jean , Girard-Bascou Jacqueline , Franck Fabrice , Wollman Francis-André , Finazzi Giovanni
Published: September 2009

State transitions correspond to a major regulation process for photosynthesis, whereby chlorophyll protein complexes responsible for light harvesting migrate between photosystem II and photosystem I in response to changes in the redox poise of the intersystem electron carriers. Here we disclose their physiological significance in
Chlamydomonas reinhardtii
using a genetic approach. Using single and double mutants defective for state transitions and/or mitochondrial respiration, we show that photosynthetic growth, and therefore biomass production, critically depends on state transitions in respiratory-defective conditions. When extra ATP cannot be provided by respiration, enhanced photosystem I turnover elicited by transition to state 2 is required for photosynthetic activity. Concomitant impairment of state transitions and respiration decreases the overall yield of photosynthesis, ultimately leading to reduced fitness. We thus provide experimental evidence that the combined energetic contributions of state transitions and respiration are required for efficient carbon assimilation in this alga.
Multisensory integration in the Müller-Lyer illusion: From vision to haptics
Authors: Mancini Flavia , Bricolo Emanuela , Vallar Giuseppe
Published: September 2009

The Müller-Lyer figure is a powerful illusion in both vision and touch, although it is still unclear whether the visual and haptic illusory effects are due to modality-specific or shared processes. In order to investigate the hypothesis of a common underlying mechanism, the performance of 24 undergraduates in a manual bisection task of the Judd variant of the Müller-Lyer figure was assessed under visual, haptic, and visuo-haptic presentations (Experiment 1). In the bimodal condition participants saw the arrowheads on the front and touched the shaft on the back of a stimulus-supporting board. Illusory effects were comparable in touch and vision and were present, albeit reduced, in the bimodal visuo-haptic condition. In Experiment 2 we used the bimodal task of Experiment 1, manipulating the spatial position of the horizontal shaft on the backside of the board. The visual arrowheads affected haptic bisection, bringing about the illusory effects, only when the shaft was aligned with them. In conclusion, illusory effects transfer cross-modally from vision to haptics only in the presence of spatial coincidence, which appears to be a crucial factor for cross-modal integration. Implications for multisensory processes are discussed.
Show or tell: Testimony is sufficient to induce the curse of knowledge in three- and four-year-olds
Authors: Bhandari Keera , Barth Hilary
Published: September 2009

Because much of what children learn extends beyond their first-hand experience, they are reliant upon the testimony of others to acquire information about aspects of the world they have not experienced directly. Here we asked whether testimony alone would be sufficient to induce cognitive biases in knowledge attribution that have been observed when children acquire information through direct observation. A total of 80 three- and four-year-old children were tested on a “curse of knowledge” task to assess their inability to override their own knowledge when asked to assess the knowledge of a naïve other. In the present study, we tested children's ability to override knowledge gained through testimony rather than knowledge gained through visual experience. Testimony alone was sufficient to induce the curse of knowledge in three- and four-year-olds. Knowledge obtained through the testimony of others is apparently subject to some of the same cognitive biases that are present when children learn through observation.