bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of CaMKIV in neurogenic effect with chronic fluoxetine treatment
Authors: Song Ning , Nakagawa Shin , Izumi Takeshi , Toda Hiroyuki , Kato Akiko , Boku Shuken , Inoue Takeshi , Sakagami Hiroyuki , Li Xiaobai , Koyama Tsukasa
Published: June 2012

Calcium-calmodulin dependent protein kinase IV (CaMKIV) is a protein kinase that has been suggested to participate in fluoxetine (FLX)-induced phosphorylation of cyclic AMP-response element binding protein (CREB). CREB is a key transcription factor in adult neurogenesis. The present study aimed at evaluating whether CaMKIV is involved in adult hippocampal neurogenesis with FLX treatment. Effects of chronic FLX on hippocampal cell proliferation, survival and phenotypes were assessed using bromodeoxyuridine (BrdU) immunohistochemistry or BrdU/neuronal nuclei (NeuN)/S100β immunofluorescence staining in wild-type (WT) and CaMKIV knockout (KO) mice. Expression and phosphorylation of CaMKIV and CREB were assessed using RT–PCR and Western blotting. The behavioural action with FLX was assessed in the novelty suppressed feeding test (NSF), which is considered neurogenesis-dependent. CaMKIV KO mice have reduced cell proliferation, but not survival in the dentate gyrus of hippocampus with chronic treatment of FLX when compared to wild littermates. Phenotype analysis showed that most newborn cells matured into neurons. Phosphorylation of CaMKIV was up-regulated in WT mice and phosphorylation of CREB was impaired in CaMKIV KO mice after FLX treatment. The behavioural effects of FLX in NSF were similar in both types. These data suggest that CaMKIV is involved in some aspects of FLX-promoting hippocampal neurogenesis.
Religious reasons in the public sphere: an empirical study of religious actors’ argumentative patterns in Swiss direct democratic campaigns
Authors: Bächtiger André , Könemann Judith , Jödicke Ansgar , Hangartner Dominik
Published: June 2012

The ‘going public’ of religious actors is taking central stage both in religious studies and political philosophy. But this ‘going public’ of religious actors is controversial. The debate revolves around the question of whether religious actors must frame their religious convictions in terms of secular reasons or whether they should be allowed to introduce religiously grounded beliefs into public political argument without constraints. Despite vigorous and ongoing debate, there is little systematic and empirical research on this question. This article focuses on the public statements of religious actors in the context of Swiss direct democratic votes on abortion and immigration. Our empirical findings reveal an interesting gap: while many political philosophers and religious thinkers have moved to a position where religious actors can – and even should – openly employ religious arguments, the practice of religious actors in Switzerland is different. The larger denominations of Catholics and Protestants especially have a tendency to use a great amount of secular vocabulary. In addition, our findings also reveal that the use of religious or secular reasons varies considerably according to different issues, different media types (religious vs. secular press), different religious traditions, different alliance structures, and different media genres, while there is no clear time trend.
Cerebral Asymmetry: A Quantitative, Multifactorial, and Plastic Brain Phenotype
Authors: Rentería Miguel E.
Published: June 2012

The longitudinal fissure separates the human brain into two hemispheres that remain connected through the corpus callosum. The left and the right halves of the brain resemble each other, and almost every structure present in one side has an equivalent structure in the other. Despite this exceptional correspondence, the two hemispheres also display important anatomical differences and there is marked lateralization of certain cognitive and motor functions such as language and handedness. However, the mechanisms that underlie the establishment of these hemispheric specializations, as well as their physiological and behavioral implications, remain largely unknown. Thanks to recent advances in neuroimaging, a series of studies documenting variation in symmetry and asymmetry as a function of age, gender, brain region, and pathological state, have been published in the past decade. Here, we review evidence of normal and atypical cerebral asymmetry, and the factors that influence it at the macrostructural level. Given the prominent role that cerebral asymmetry plays in the organization of the brain, and its possible implication in neurodevelopmental and psychiatric conditions, further research in this area is anticipated.
Mutter-Kind-Interaktion bei Frühgeborenen
Authors: Lilienfeld Mirjam von , Wendrich Daniela , Ganseforth Catharina , Lehmkuhl Gerd , Roth Bernhard , Nußbeck Susanne , Mehler Katrin , Kribs Angela
Published: June 2012

Die Mutter-Kind-Interaktion (MKI) Frühgeborener ist im Vergleich zu Reifgeborenen durch eine erhöhte mütterliche Intrusivität und Kontrolle gekennzeichnet. Analysiert wurde die MKI von Früh- und Reifgeborenen im Alter von 36 Monaten. 39 Frühgeborene < 1500 g (Studiengruppe) und 26 Reifgeborene (Kontrollgruppe) wurden im korrigierten Alter von 36 Monaten mittels Mannheimer Methode zur standardisierten Beobachtung der MKI im Kleinkindalter untersucht. Hierzu werden zwei fünfminütige Interaktionssituationen videographisch aufgezeichnet. Für die Lernsituation konnte nachgewiesen werden, dass die Mütter Frühgeborener weniger supportiv, häufiger restriktiv und unangemessen steuern, „negativer“ auf ihre Kinder reagieren und häufiger „negative“ Interaktionsauffälligkeiten zeigen. In der Spielsituation zeigte sich, dass Mütter frühgeborener Kinder häufiger negative Interaktionsauffälligkeiten sowie eine höhere negative Gestimmtheit und eine unangemessenere Steuerung aufweisen. Die Lernsituation zeigte sich in der Gruppe der Frühgeborenen als die „schwierigere“ Interaktion. Die Problematik der Mutter- Kind-Interaktion Frühgeborener bedarf besonderer Beachtung sowie früher Interventionen.
Psychopathy
Authors: Petermann Franz , Koglin Ute
Published: June 2012

Das Konzept „Psychopathy“ wird in den letzten Jahren für das Kindes- und Jugendalter spezifiziert und bietet die Chance, Extremformen aggressiv-dissozialen Verhaltens zu beschreiben und zu klassifizieren. Erscheinungsformen, Prävalenzraten und Verlaufsstudien tragen dazu bei, dass die Aussagekraft des Konzepts für die klinische Praxis zunimmt. Die Tatsache, dass das DSM-V sich dieser Subgruppe annimmt, wird die Akzeptanz des Konzeptes und Forschungsaktivitäten intensivieren.
Fluxes and distribution of dissolved iron in the eastern (sub‐) tropical North Atlantic Ocean
Authors: Rijkenberg Micha J. A. , Steigenberger Sebastian , Powell Claire F. , van Haren Hans , Patey Matthew D. , Baker Alex R. , Achterberg Eric P.
Published: June 2012

Aeolian dust transport from the Saharan/Sahel desert regions is considered the dominant external input of iron (Fe) to the surface waters of the eastern (sub‐) tropical North Atlantic Ocean. To test this hypothesis, we investigated the sources of dissolved Fe (DFe) and quantified DFe fluxes to the surface ocean in this region. In winter 2008, surface water DFe concentrations varied between <0.1 nM and 0.37 nM, with an average of 0.13 ± 0.07 nM DFe (n = 194). A strong correlation between mixed layer averaged concentrations of dissolved aluminum (DAl), a proxy for dust input, and DFe indicated dust as a source of DFe to the surface ocean. The importance of Aeolian nutrient input was further confirmed by an increase of 0.1 nM DFe and 0.05 μM phosphate during a repeat transect before and after a dust event. An exponential decrease of DFe with increasing distance from the African continent, suggested that continental shelf waters were a source of DFe to the northern part of our study area. Relatively high Fe:C ratios of up to 3 × 10−5 (C derived from apparent oxygen utilization (AOU)) indicated an external source of Fe to these African continental shelf waters. Below the wind mixed layer along 12°N, enhanced DFe concentrations (>1.5 nM) correlated positively with apparent oxygen utilization (AOU) and showed the importance of organic matter remineralization as an DFe source. As a consequence, vertical diffusive mixing formed an important Fe flux to the surface ocean in this region, even surpassing that of a major dust event.
On the variability of sea drag in finite water depth
Authors: Toffoli A. , Loffredo L. , Le Roy P. , Lefèvre J.‐M. , Babanin A. V.
Published: June 2012

The coupling between the atmospheric boundary layer and the ocean surface in large‐scale models is usually parameterized in terms of the sea drag coefficient, which is routinely estimated as a function of mean wind speed. The scatter of data around such parametric dependencies, however, is very significant and imposes a serious limitation on the forecasts and predictions that make use of sea surface drag parameterizations. The analysis of an atmospheric and wave data set collected in finite water depth at the Lake George measurement site (Australia) suggests that this variability relates to a number of parameters at the air‐sea interface other than wind speed alone. In particular, results indicate that the sea drag depends on water depth and wave steepness, which make the wave profile more vertically asymmetric, and the concentration of water vapor in the air, which modifies air density and friction velocity. These dependencies are used to derive parametric functions based on the combined contribution of wind, waves and relative humidity. A standard statistical analysis confirms a substantial improvement in the prediction of the drag coefficient and sea surface roughness when additional parameters are taken into account.
A global comparison of GEOS‐Chem‐predicted and remotely‐sensed mineral dust aerosol optical depth and extinction profiles
Authors: Johnson Matthew S. , Meskhidze Nicholas , Praju Kiliyanpilakkil Velayudhan
Published: June 2012

Dust aerosol optical depth (AOD) and vertical distribution of aerosol extinction predicted by a global chemical transport model (GEOS‐Chem) are compared to space‐borne data from the Moderate‐resolution Imaging Spectroradiometer (MODIS), Multi‐Angle Imaging SpectroRadiometer (MISR), and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) for March 2009 to February 2010. Model‐predicted and remotely‐sensed AOD/aerosol extinction profiles are compared over six regions where aerosol abundances are dominated by mineral dust. Calculations indicate that over the regions examined in this study (with the exception of Middle Eastern dust sources) GEOS‐Chem predicts higher AOD values compared to MODIS and MISR. The positive bias is particularly pronounced over the Saharan dust source regions, where model‐predicted AOD values are a factor of 2 to 3 higher. The comparison with CALIPSO‐derived dust aerosol extinction profiles revealed that the model overestimations of dust abundances over the study regions primarily occur below ∼4 km, suggesting excessive emissions of mineral dust and/or uncertainties in dust optical properties. The implementation of a new dust size distribution scheme into GEOS‐Chem reduced the yearly‐mean positive bias in model‐predicted AOD values over the study regions. The results were most noticeable over the Saharan dust source regions where the differences between model‐predicted and MODIS/MISR retrieved AOD values were reduced from 0.22 and 0.17 to 0.02 and −0.04, respectively. Our results suggest that positive/negative biases between satellite and model‐predicted aerosol extinction values at different altitudes can sometimes even out, giving a false impression for the agreement between remotely‐sensed and model‐predicted column‐integrated AOD data.
Specific discharge variability in a boreal landscape
Authors: Lyon Steve W. , Nathanson Marcus , Spans André , Grabs Thomas , Laudon Hjalmar , Temnerud Johan , Bishop Kevin H. , Seibert Jan
Published: June 2012

Specific discharge variations within a mesoscale catchment were studied on the basis of three synoptic sampling campaigns. These were conducted during stable flow conditions within the Krycklan catchment study area in northern Sweden. During each campaign, about 80 individual locations were measured for discharge draining from catchment areas ranging between 0.12 and 67 km2. These discharge samplings allowed for the comparison between years within a given season (September 2005 versus September 2008) and between seasons within a given year (May 2008 versus September 2008) of specific discharge across this boreal landscape. There was considerable variability in specific discharge across this landscape. The ratio of the interquartile range (IQR) defined as the difference between the 75th and 25th percentiles of the specific discharges to the median of the specific discharges ranged from 37% to 43%. Factor analysis was used to explore potential relations between landscape characteristics and the specific discharge observed for 55 of the individual locations that were measured in all three synoptic sampling campaigns. Percentage wet area (i.e., wetlands, mires, and lakes) and elevation were found to be directly related to the specific discharge during the drier September 2008 sampling while potential annual evaporation was found to be inversely related. There was less of a relationship determined during the wetter post spring flood May 2008 sampling and the late summer rewetted September 2005 sampling. These results indicate the ability of forests to “dry out” parts of the catchment over the summer months while wetlands “keep wet” other parts. To demonstrate the biogeochemical implications of such spatiotemporal variations in specific discharge, we estimate dissolved organic carbon (DOC) exports with available data for the May 2008 and September 2008 samplings using both the spatially variable observed specific discharges and the spatially constant catchment average values. The average absolute difference in DOC export for the various subcatchments between using a variable and using a constant specific discharge was 28% for the May 2008 sampling and 20% for the September 2008 sampling.
Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States
Authors: Walvoord Michelle A. , Voss Clifford I. , Wellman Tristan P.
Published: June 2012

Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km2) subbasin within the Yukon River Basin, provides the basis for this investigation. Model simulations that represent an assumed permafrost thaw sequence reveal the following trends with decreasing permafrost coverage: (1) increased groundwater discharge to rivers, consistent with historical trends in base flow observations in the Yukon River Basin, (2) potential for increased overall groundwater flux, (3) increased spatial extent of groundwater discharge in lowlands, and (4) decreased proportion of suprapermafrost (shallow) groundwater contribution to total base flow. These trends directly affect the chemical composition and residence time of riverine exports, the state of groundwater‐influenced lakes and wetlands, seasonal river‐ice thickness, and stream temperatures. Presently, the YFB is coarsely mapped as spanning the continuous‐discontinuous permafrost transition that model analysis shows to be a critical threshold; thus, the YFB may be on the verge of major hydrologic change should the current permafrost extent decrease. This possibility underscores the need for improved characterization of permafrost and other hydrogeologic information in the region via geophysical techniques, remote sensing, and ground‐based observations.
Fluid and gas fluxes from the Logatchev hydrothermal vent area
Authors: Schmale Oliver , Walter Maren , Schneider von Deimling Jens , Sültenfuß Jürgen , Walker Sharon , Rehder Gregor , Keir Robin
Published: June 2012

The Logatchev hydrothermal field at 14°45′N on the MAR is characterized by gas plumes that are enriched in methane and helium compared to the oceanic background. We investigated CH4 concentration and δ13C together with δ3He in the water column of that region. These data and turbidity measurements indicate that apart from the known vent fields, another vent site exists northeast of the vent field Logatchev 1. The distribution of methane and 3He concentrations along two sections were used in combination with current measurements from lowered acoustic Doppler current profilers (LADCP) to calculate the horizontal plume fluxes of these gases. According to these examinations 0.02 μmol s−1 of 3He and 0.21 mol s−1 of methane are transported in a plume that flows into a southward direction in the central part of the valley. Based on 3He measurements of vent fluid (22 ± 6 pM), we estimate a total vent flux in this region of about 900 L s−1 and a total flux of CH4 of 3.2 mol s−1.
Boundary layer ozone pollution caused by future aircraft emissions
Authors: Hauglustaine Didier A. , Koffi Brigitte
Published: June 2012

In addition to their impact on the radiative forcing of climate and on the composition of the upper‐troposphere and lower‐stratosphere region, global aircraft NOx emissions are found to contribute significantly to transport emission induced future ozone air pollution in Europe and in the United States. Based on various projections of 2050 emissions of short‐lived pollutants by the three major transport sectors (i.e., road transportation, shipping, and aircraft), we show that aircraft NOx exhaust contribute by 30–40% to the summertime 8h‐average daily maximum surface ozone increase due to transport emissions in Europe and in the United States. Depending on the future scenario, over these two regions, an annual mean contribution of aircraft emissions of 25–48% to the boundary layer ozone burden increase associated with transport emissions in 2050 is simulated. Shipping emissions also represent a significant, and often dominant, contribution to future boundary layer ozone change due to transport emissions over land downwind of maritime corridors in the range 32–60% depending on the emission scenario. In the context of tighter emission standards for road transport in the future, these results indicate that aircraft and shipping emissions deserve consideration as a mean to improve air quality and reduce ozone pollution episodes.
Solar and thermal radiation profiles and radiative forcing measured through the atmosphere
Authors: Philipona Rolf , Kräuchi Andreas , Brocard Emmanuel
Published: June 2012

Solar shortwave and thermal longwave radiation at the Earth's surface and at the top of the atmosphere is commonly measured at surface stations, from airplanes and from satellites. Here we show radiative flux profiles measured with radiosondes ascending from the Earth's surface to 35 km into the stratosphere. During two‐hour flights solar shortwave and thermal longwave radiation are measured both downward and upward with four individual sensors. Daytime solar and thermal radiation is compared to nighttime measurements and 24‐hour average radiation budget profiles are shown through the atmosphere. However, of even greater importance with regard to climate change are measured upward and downward longwave greenhouse radiation profiles. Their changes with temperature and water vapor enable direct measurement of radiative forcing through the atmosphere. Measurements during two cloud‐free nights with different temperature and different water vapor amount, show an almost equal but opposite net longwave radiation change, or water vapor greenhouse forcing, downwards to the surface and upward into space. Radiative flux profiles clearly illustrate the Earth's atmospheric greenhouse effect, and allow important investigations of clouds and other atmospheric constituents and their effects on shortwave reflection, as well as longwave emission towards the surface and into space.
Extended Kalman Filter framework for forecasting shoreline evolution
Authors: Long Joseph W. , Plant Nathaniel G.
Published: June 2012

A shoreline change model incorporating both long‐ and short‐term evolution is integrated into a data assimilation framework that uses sparse observations to generate an updated forecast of shoreline position and to estimate unobserved geophysical variables and model parameters. Application of the assimilation algorithm provides quantitative statistical estimates of combined model‐data forecast uncertainty which is crucial for developing hazard vulnerability assessments, evaluation of prediction skill, and identifying future data collection needs. Significant attention is given to the estimation of four non‐observable parameter values and separating two scales of shoreline evolution using only one observable morphological quantity (i.e. shoreline position).
Conversion from HST ACS and STIS auroral counts into brightness, precipitated power, and radiated power for H2 giant planets
Authors: Gustin J. , Bonfond B. , Grodent D. , Gérard J.‐C.
Published: June 2012

The STIS and ACS instruments onboard HST are widely used to study the giant planet's aurora. Several assumptions have to be made to convert the instrumental counts into meaningful physical values (type and bandwidth of the filters, definition of the physical units, etc…), but these may significantly differ from one author to another, which makes it difficult to compare the auroral characteristics published in different studies. We present a method to convert the counts obtained in representative ACS and STIS imaging modes/filters used by the auroral scientific community to brightness, precipitated power and radiated power in the ultraviolet (700–1800 Å). Since hydrocarbon absorption may considerably affect the observed auroral emission, the conversion factors are determined for several attenuation levels. Several properties of the auroral emission have been determined: the fraction of the H2 emission shortward and longward of the HLy‐α line is 50.3% and 49.7% respectively, the contribution of HLy‐α to the total unabsorbed auroral signal has been set to 9.1% and an input of 1 mW m−2 produces 10 kR of H2 in the Lyman and Werner bands. A first application sets the order of magnitude of Saturn's auroral characteristics in the total UV bandwidth to a brightness of 10 kR and an emitted power of ∼2.8 GW. A second application uses published brightnesses of Europa's footprint to determine the current density associated with the Europa auroral spot: 0.21 and 0.045 μA m−2 assuming no hydrocarbon absorption and a color ratio of 2, respectively. Factors to extend the brightnesses observed with Cassini‐UVIS to total H2 UV brightnesses are also provided.
On the runup of long waves on a plane beach
Authors: Chan I‐Chi , Liu Philip L.‐F.
Published: June 2012

Using the records of free surface fluctuations at several locations during the 2011 Japan Tohoku tsunami, we first show that the leading tsunami waves in both near‐field and far‐field regions are small amplitude long waves. These leading waves are very different from solitary waves. We then focus on investigating the evolution and runup of non‐breaking long waves on a plane beach, which is connected to a constant depth region. For this purpose, we develop a Lagrangian numerical model to solve the nonlinear shallow water equations. The Lagrangian approach tracks the moving shoreline directly without invoking any additional approximation. We also adopt and extend the analytical solutions by Synolakis (1987) and Madsen and Schäffer (2010) for runup and rundown of cnoidal waves and a train of multiple solitary waves. The analytical solutions for cnoidal waves compare well with the existing experimental data and the direct numerical results when wave amplitudes are small. However, large discrepancies appear when the incident amplitudes are finite. We also examine the relationship between the maximum runup height and the leading wave form. It is concluded that for a single wave the accelerating phase of the incident wave controls the maximum runup height. Finally, using the analytical solutions for the approximated wave forms of the leading tsunamis recorded at Iwate South station from the 2011 Tohoku Japan tsunami, we estimate the runup height.
Long‐term ionospheric anomaly monitoring for ground based augmentation systems
Authors: Jung Sungwook , Lee Jiyun
Published: June 2012

Extreme ionospheric anomalies can pose a potential integrity threat to ground‐based augmentation of the Global Positioning System (GPS), and thus the development of ionospheric anomaly threat models for each region of operation is essential for system design and operation. This paper presents a methodology for automated long‐term ionospheric anomaly monitoring, which will be used to build an ionospheric anomaly threat model, evaluate its validity over the life cycle of the system, continuously monitor ionospheric anomalies, and update the threat model if necessary. This procedure automatically processes GPS data collected from external networks and estimates ionospheric gradients at regular intervals. If ionospheric gradients large enough to be potentially hazardous to users are identified, manual data examination is triggered. This paper also develops a simplified truth processing method to create precise ionospheric delay estimates in near real‐time, which is the key to automating the ionospheric monitoring procedure. The performance of the method is examined using data from the 20 November 2003 and 9 November 2004 ionospheric storms. These results demonstrate the effectiveness of simplified truth processing within long‐term ionosphere monitoring. From the case studies, the automated procedure successfully identified extreme ionospheric anomalies, including the two worst ionospheric gradients observed and validated previously based on manual analysis. The automation of data processing enables us to analyze ionospheric data continuously going forward and to more accurately categorize ionospheric behavior under both nominal and anomalous conditions.
Dynamics of ammonia-oxidizing archaea and bacteria populations and contributions to soil nitrification potentials
Authors: Taylor Anne E , Zeglin Lydia H , Wanzek Thomas A , Myrold David D , Bottomley Peter J
Published: June 2012

It is well known that the ratio of ammonia-oxidizing archaea (AOA) and bacteria (AOB) ranges widely in soils, but no data exist on what might influence this ratio, its dynamism, or how changes in relative abundance influences the potential contributions of AOA and AOB to soil nitrification. By sampling intensively from cropped-to-fallowed and fallowed-to-cropped phases of a 2-year wheat/fallow cycle, and adjacent uncultivated long-term fallowed land over a 15-month period in 2010 and 2011, evidence was obtained for seasonal and cropping phase effects on the soil nitrification potential (NP), and on the relative contributions of AOA and AOB to the NP that recovers after acetylene inactivation in the presence and absence of bacterial protein synthesis inhibitors. AOB community composition changed significantly (P⩽0.0001) in response to cropping phase, and there were both seasonal and cropping phase effects on the amoA gene copy numbers of AOA and AOB. Our study showed that the AOA:AOB shifts were generated by a combination of different phenomena: an increase in AOA amoA abundance in unfertilized treatments, compared with their AOA counterparts in the N-fertilized treatment; a larger population of AOB under the N-fertilized treatment compared with the AOB community under unfertilized treatments; and better overall persistence of AOA than AOB in the unfertilized treatments. These data illustrate the complexity of the factors that likely influence the relative contributions of AOA and AOB to nitrification under the various combinations of soil conditions and NH4+-availability that exist in the field.
Clinical Perspectives on Esophageal Disorders in Infants
Authors: Chan Chin Yee , Jadcherla Sudarshan R.
Published: June 2012

Esophageal pathologies are complex and lend themselves to multivariable analysis before a definitive diagnosis can be considered. It is imperative that the clinician establish a methodology for selecting the appropriate technological assessment within scientific testing parameters to establish optimal clinicopathological presentation and determine best practice for patient care.
Terahertz scattering by dense media
Authors: Kaushik Mayank , Ng Brian W.-H. , Fischer Bernd M. , Abbott Derek
Published: June 2012

Frequency dependent absorption of a given material at distinct frequencies in the terahertz (THz) range is commonly used as a spectral fingerprint for material identification and classification. However, in the presence of strong scattering, these features can often become distorted or altered. Thus, there is an important need to understand how scattering from a sample alters the THz signal. In this letter, we propose an iterative algorithm that builds on the effective field theory proposed by P. C. Waterman and R. Truell [J. Math. Phys. 2, 512–537 (1961)] and offers a rather simple and computationally efficient method for accurately explaining the multiple scattering response of a medium.
Investigation of size effects on the structure of liquid GeSe2 calculated via first-principles molecular dynamics
Authors: Micoulaut Matthieu , Le Roux Sébastien , Massobrio Carlo
Published: June 2012

The structural properties of liquid GeSe2 have been calculated by first-principles molecular dynamics by using a periodic simulation box containing N = 480 atoms. This has allowed a comparison with previous results obtained on a smaller system size (N = 120) [M. Micoulaut, R. Vuilleumier, and C. Massobrio, Phys. Rev. B 79, 214205 (2009)10.1103/PhysRevB.79.214205]. In the domain of first-principles molecular dynamics, we obtain an assessment of system size effects of unprecedented quality. Overall, no drastic differences are found between the two sets of results, confirming that N = 120 is a suitable size to achieve a realistic description of this prototypical disordered network. However, for N = 480, short range properties are characterized by an increase of chemical order, the number of Ge tetrahedra coordinated to four Se atoms being larger. At the intermediate range order level, size effect mostly modify the low wavevector region (k ∼1 Å−1) in the concentration-concentration partial structure factor.
Phase behavior of colloidal suspensions with critical solvents in terms of effective interactions
Authors: Mohry T. F. , Maciołek A. , Dietrich S.
Published: June 2012

We study the phase behavior of colloidal suspensions the solvents of which are considered to be binary liquid mixtures undergoing phase segregation. We focus on the thermodynamic region close to the critical point of the accompanying miscibility gap. There, due to the colloidal particles acting as cavities in the critical medium, the spatial confinements of the critical fluctuations of the corresponding order parameter result in the effective, so-called critical Casimir forces between the colloids. Employing an approach in terms of effective, one-component colloidal systems, we explore the possibility of phase coexistence between two phases of colloidal suspensions, one being rich and the other being poor in colloidal particles. The reliability of this effective approach is discussed.
Upscaling from particle models to entropic gradient flows
Authors: Dirr Nicolas , Laschos Vaios , Zimmer Johannes
Published: June 2012

We prove that, for the case of Gaussians on the real line, the functional derived by a time discretization of the diffusion equation as entropic gradient flow is asymptotically equivalent to the rate functional derived from the underlying microscopic process. This result strengthens a conjecture that the same statement is actually true for all measures with second finite moment.
Energy conservation in molecular dynamics simulations of classical systems
Authors: Toxvaerd Søren , Heilmann Ole J. , Dyre Jeppe C.
Published: June 2012

Classical Newtonian dynamics is analytic and the energy of an isolated system is conserved. The energy of such a system, obtained by the discrete “Verlet” algorithm commonly used in molecular dynamics simulations, fluctuates but is conserved in the mean. This is explained by the existence of a “shadow Hamiltonian” \documentclass[12pt]{minimal}\begin{document}$\tilde{H}$\end{document}H̃ [S. Toxvaerd, Phys. Rev. E 50, 2271 (1994)], i.e., a Hamiltonian close to the original H with the property that the discrete positions of the Verlet algorithm for H lie on the analytic trajectories of \documentclass[12pt]{minimal}\begin{document}$\tilde{H}$\end{document}H̃. The shadow Hamiltonian can be obtained from H by an asymptotic expansion in the time step length. Here we use the first non-trivial term in this expansion to obtain an improved estimate of the discrete values of the energy. The investigation is performed for a representative system with Lennard-Jones pair interactions. The simulations show that inclusion of this term reduces the standard deviation of the energy fluctuations by a factor of 100 for typical values of the time step length. Simulations further show that the energy is conserved for at least one hundred million time steps provided the potential and its first four derivatives are continuous at the cutoff. Finally, we show analytically as well as numerically that energy conservation is not sensitive to round-off errors.
A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
Authors: Bayrak Pehlivan İ. , Runnerstrom E. L. , Li S.-Y. , Niklasson G. A. , Milliron D. J. , Granqvist C. G.
Published: June 2012

Chemically prepared ∼13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This type of polymer electrolyte is of large interest for opto-ionic devices such as laminated electrochromic smart windows.
Strain-assisted bandgap modulation in Zn based II-VI semiconductors
Authors: Yadav S. K. , Ramprasad R.
Published: June 2012

The electronic structure of bulk ZnX (X = O, S, Se, and Te) under uniaxial strain along the [0001] direction or equibiaxial strain along the (0001) plane is investigated using hybrid density functional theory calculations and many-body perturbation theory. It is shown that compressive uniaxial (or tensile equibiaxial) strains lead to a structural phase transition in all the ZnX systems. This is accompanied by large reductions in the bandgap of ZnSe and ZnTe, spanning the entire visible spectrum.
Performance of a short “magnetic bottle” electron spectrometer
Authors: Mucke M. , Förstel M. , Lischke T. , Arion T. , Bradshaw A. M. , Hergenhahn U.
Published: June 2012

In this article, a newly constructed electron spectrometer of the magnetic bottle type is described. The instrument is part of an apparatus for measuring the electron spectra of free clusters using synchrotron radiation. Argon and helium outer valence photoelectron spectra have been recorded in order to investigate the characteristic features of the spectrometer. The energy resolution (E/ΔE) has been found to be ∼30. Using electrostatic retardation of the electrons, it can be increased to at least 110. The transmission as a function of kinetic energy is flat, and is not impaired much by retardation with up to 80% of the initial kinetic energy. We have measured a detection efficiency of most probably \documentclass[12pt]{minimal}\begin{document}$0.6^{+0.05}_{-0.1}$\end{document}0.6−0.1+0.05, but at least of 0.4. Results from testing the alignment of the magnet, and from trajectory simulations, are also discussed.
Electromechanical coupling in anodic niobium oxide: Electric field-induced strain, internal stress, and dielectric response
Authors: Van Overmeere Q. , Blaffart F. , La Mantia F. , Di Quarto F. , Proost J.
Published: June 2012

Seemingly, contradictory results have been reported so far for electrostriction in anodic oxides. Furthermore, no definitive agreement could be obtained with theory. In this paper, in situ techniques are combined to elucidate electrostriction in anodic niobium oxide. The dependence of strain, internal stress, and dielectric constant on the electric field is measured by, respectively, spectroscopic ellipsometry, curvature, and impedance measurements. The through-thickness strain is tensile and proportional to the square of the electric field. The in-plane internal stress is compressive and proportional to the square of the electric field at low field values. The internal stress is predicted relatively well by the Maxwell stress because of the weak dependence of the dielectric constant on the volume change of the oxide. The dielectric constant decreases with the electric field, the dependence being quadratic. While the evolution of the strain and stress with the electric field can be ascribed to the dependence of the dielectric constant on strain, the dependence of the dielectric constant on the electric field contains an explicit strain and electric field dependence. A mechanism for the latter is proposed.
Genetic population structure and connectivity in a commercially exploited and wide-ranging deepwater shark, the leafscale gulper (Centrophorus squamosus)
Authors: Veríssimo A. , McDowell J. R. , Graves J. E.
Published: June 2012

The leafscale gulper (Centrophorus squamosus) is a wide-ranging deepwater benthopelagic shark threatened by commercial fisheries in parts of its range. Despite concerns about resource sustainability, little is known about the population structure and connectivity between critical habitats of the leafscale gulper. This study investigates the genetic population structure and the migration patterns of C. squamosus using nuclear microsatellites and mitochondrial NADH dehydrogenase subunit 2 (ND2) gene sequences. Genetic diversity was estimated and compared among sample collections from off Ireland, Portugal, the Azores, South Africa and New Zealand. The null hypothesis of genetic homogeneity among all collections was not rejected by the nuclear loci (FST (the overall genetic differentiation among sample collections) = –0.002, P = 0.88), but we found long-term genetic divergence between New Zealand and the remaining collections at the mtDNA ND2 (FCT (genetic differentation among groups of sample collections) = 0.366, P = 0.000). Migration rate estimates indicated limited female dispersal across the Indian Ocean whereas males showed less restricted dispersal. Our results are consistent with a single genetic stock of C. squamosus and the existence of sex-biased dispersal across the Indian Ocean. Widespread genetic homogeneity at nuclear loci minimizes the loss of unique adaptive genetic diversity in the event of localised depletion. However, high local fishing mortality may have far reaching impacts given the marked sex- and maturity-stage-based habitat partitioning previously reported for C. squamosus.
Intra- and inter-annual changes in chemistry of Australian glacial lakes
Authors: Green Ken
Published: June 2012

The chemical characteristics of five seasonally ice-covered lakes in the Snowy Mountains were measured monthly from 2006 to 2009. Although N and P concentrations were significantly higher in rainfall than snowfall, concentrations peaked in lakes in winter rather than summer. This was linked to continuous winter nutrient flow into the lakes from melting snowpack and continued biogeochemical processes in unfrozen soil at a time when biological activity beneath the lake ice was depressed. In contrast to high altitude lakes elsewhere, there was no spring ionic pulse of nutrients. Lake pH fluctuated throughout the ice-free period between 6.9 and 6.5, falling to 6.1–6.0 beneath ice cover, before rising abruptly after ice break-up. Earlier ice break-up in recent years has resulted in an earlier increase in pH, and decrease in concentrations of NH3-N and NOx-N. In years with least snowfall and early ice break-up, winter peaks of NH3-N were lowest whereas both PO4-P and NOx-N showed winter peaks of various concentrations in medium years rather than extreme years. Rising winter and/or spring temperatures resulting in changes in precipitation from snow to rain could lead to increased nutrient deposition, with rain carrying an order of magnitude more nutrients than does snow.
Small home range in southern Australia's largest resident reef fish, the western blue groper (Achoerodus gouldii): implications for adequacy of no-take marine protected areas
Authors: Bryars Simon , Rogers Paul , Huveneers Charlie , Payne Nicholas , Smith Ian , McDonald Bryan
Published: June 2012

No-take marine protected areas (MPAs) represent an effective biodiversity conservation tool for a range of species including resident reef fishes that are intrinsically vulnerable to overfishing and other localised impacts. The western blue groper (Achoerodus gouldii) is the largest permanent-resident reef teleost in southern Australian waters and has the second-oldest recorded age of any labrid at 70 years. Acoustic telemetry was used to investigate whether adult A. gouldii can be effectively protected within adequately sized no-take MPAs. Ten passive acoustic receivers tracked the movements of 15 A. gouldii individuals (69–112-cm total length; 7–31-kg weight) at a site off north-western Kangaroo Island, South Australia. Most of the fish displayed high site fidelity (91–100% residence time for 10 of the 11 fish with useful data) for a narrow strip of fringing coastal reef (~1-km length by ~40-m width) throughout a 12-month period. Mean home-range along-shore length and area were estimated at 1076 ± 83 m (s.e.), and 45 188 ± 3497 m2, respectively (n = 11 fish with useful data). Comparison with other resident temperate-reef teleosts indicated no relationship between fish length and home-range area, and that A. gouldii has a relatively small home range. The high site fidelity and small home range of adult A. gouldii individuals makes localised populations amenable to a high level of protection within no-take MPAs.
Bycatch of Shortnose Sturgeon in the Commercial American Shad Fishery of the Altamaha River, Georgia
Authors: Bahn Robert A. , Fleming Joel E. , Peterson Douglas L.
Published: June 2012

The objective of our study was to estimate total bycatch and mortality of shortnose sturgeon Acipenser brevirostrum in the anchored-gill-net portion of the commercial fishery for American shad Alosa sapidissima in the Altamaha River, Georgia, from 2007 to 2009. We conducted on-the-water counts of commercial nets to estimate total fishing effort. Catch per unit effort was estimated from log books and direct observations of net retrievals by randomly selected commercial fishermen. During the 3 years of the study, the total estimated bycatch of shortnose sturgeon was 71, 53, and 498 fish, respectively. Recent studies have estimated the abundance of adult shortnose sturgeon in the Altamaha River to be approximately 1,800 individuals. Our study showed that catch per unit effort was highest during January and February of 2009 in upriver areas where previous research had identified several spawning locations. Our results also showed that the mortality of captured shortnose sturgeon was low in all 3 years (<8%), although we did not assess postrelease survival. Although closure of critical habitats may or may not be an important component of protecting shortnose sturgeon spawning habitat, our results suggest that on the Altamaha River, delaying the opening of commercial American shad fishing in the upper river until after 1 March would almost completely eliminate bycatch of migrating shortnose sturgeon and result in a minor reduction in American shad landings.

Received February 16, 2011; accepted February 16, 2012
Phosphatidylinositol 3,5-bisphosphate plays a role in the activation and subcellular localization of mechanistic target of rapamycin 1
Authors: Bridges Dave , Ma Jing-Tyan , Park Sujin , Inoki Ken , Weisman Lois S. , Saltiel Alan R.
Published: June 2012

The kinase complex mechanistic target of rapamycin 1 (mTORC1) plays an important role in controlling growth and metabolism. We report here that the stepwise formation of phosphatidylinositol 3-phosphate (PI(3)P) and phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) regulates the cell type–specific activation and localization of mTORC1. PI(3)P formation depends on the class II phosphatidylinositol 3-kinase (PI3K) PI3K-C2α, as well as the class III PI3K Vps34, while PI(3,5)P2 requires the phosphatidylinositol-3-phosphate-5-kinase PIKFYVE. In this paper, we show that PIKFYVE and PI3K-C2α are necessary for activation of mTORC1 and its translocation to the plasma membrane in 3T3-L1 adipocytes. Furthermore, the mTORC1 component Raptor directly interacts with PI(3,5)P2. Together these results suggest that PI(3,5)P2 is an essential mTORC1 regulator that defines the localization of the complex.
Fission yeast Alp14 is a dose-dependent plus end–tracking microtubule polymerase
Authors: Al-Bassam Jawdat , Kim Hwajin , Flor-Parra Ignacio , Lal Neeraj , Velji Hamida , Chang Fred
Published: June 2012

XMAP215/Dis1 proteins are conserved tubulin-binding TOG-domain proteins that regulate microtubule (MT) plus-end dynamics. Here we show that Alp14, a XMAP215 orthologue in fission yeast, Schizosaccharomyces pombe, has properties of a MT polymerase. In vivo, Alp14 localizes to growing MT plus ends in a manner independent of Mal3 (EB1). alp14-null mutants display short interphase MTs with twofold slower assembly rate and frequent pauses. Alp14 is a homodimer that binds a single tubulin dimer. In vitro, purified Alp14 molecules track growing MT plus ends and accelerate MT assembly threefold. TOG-domain mutants demonstrate that tubulin binding is critical for function and plus end localization. Overexpression of Alp14 or only its TOG domains causes complete MT loss in vivo, and high Alp14 concentration inhibits MT assembly in vitro. These inhibitory effects may arise from Alp14 sequestration of tubulin and effects on the MT. Our studies suggest that Alp14 regulates the polymerization state of tubulin by cycling between a tubulin dimer–bound cytoplasmic state and a MT polymerase state that promotes rapid MT assembly.
Critical role of AIM2 in Mycobacterium tuberculosis infection
Authors: Saiga Hiroyuki , Kitada Shoko , Shimada Yosuke , Kamiyama Naganori , Okuyama Megumi , Makino Masahiko , Yamamoto Masahiro , Takeda Kiyoshi
Published: June 2012

Abstract

Absent in melanoma 2 (AIM2) is a sensor of cytosolic DNA that is responsible for activation of the inflammasome and host immune responses to DNA viruses and intracellular bacteria. However, the role of AIM2 in host defenses against Mycobacterium tuberculosis is unknown. Here, we show that AIM2-deficient mice were highly susceptible to intratracheal infection with M. tuberculosis and that this was associated with defective IL-1± and IL-18 production together with impaired Th1 responses. Macrophages from AIM2-deficient mice infected with M. tuberculosis showed severely impaired secretion of IL-1± and IL-18 as well as activation of the inflammasome, determined by caspase-1 cleavage. Genomic DNA extracted from M. tuberculosis (Mtb DNA) induced caspase-1 activation and IL-1±/IL-18 secretion in an AIM2-dependent manner. Mtb DNA, which was present in the cytosol, co-localized with AIM2. Taken together, these findings demonstrate that AIM2 plays an important role in M. tuberculosis infection through the recognition of Mtb DNA.