bluuebunny/crossref_metadata_2025 huggingface dataset:
Plötzlich auftretende Leistungsintoleranz
Authors: Anderegg  , Schwick  , Schmid
Published: September 2007

Dieser Fall beschreibt die Differentialdiagnosen und Abklärungsschritte mittels Spiroergometrie bei einer Patientin mit akut aufgetretener Leistungsintoleranz und illustriert wie eine chronotrope Inkompetenz bei belastungsabhängigem AV-Block II als Ursache eruiert werden konnte.
Temperature and productivity influences on U37K′ and their possible relation to solar forcing of the Mediterranean winter
Authors: Versteegh G. J. M. , de Leeuw J. W. , Taricco C. , Romero A.
Published: September 2007

To assess the extent and nature of human‐induced climate change, we need to understand natural climate variability. This heavily relies on proxy‐based climate reconstructions, calling for excellent understanding of the conditions represented by the proxies. Here we report on an alkenone‐based (U37K′) sea surface temperature (SST) proxy record originating from south Italian marine sediments, and covering 1305 A.D. to 1979 A.D. with a 3.87 year resolution. The shallow‐water cores, extracted from the Gallipoli terrace in the Gulf of Taranto, were dated by the Torino group with high accuracy over the last two millennia, using radiometric and tephroanalysis methods. On the basis of comparison with historical and satellite‐derived climate and productivity data, we propose that U37K′ reflects mainly SST of the cooler part of the year and is modified by variation in magnitude and timing of peak alkenone production on the seasonal temperature cycle. Comparison of the U37K′ record with the record of atmospheric Δ14C, a proxy for solar energy variability, shows a high correlation (r = −0.73) for the period between 1420 A.D. and before human interference with the Δ14C record by combustion of fossil carbon and the release of radioactive isotopes by nuclear tests. This suggests a centennial‐scale solar forcing. We propose that wind‐induced mixing resulting from Mediterranean climate dynamics plays a crucial role in translating solar activity to alkenone productivity and SST during the cooler part of the year.
Insights into the late Cenozoic configuration of the Laurentide Ice Sheet from40Ar/39Ar dating of glacially transported minerals in midcontinent tills
Authors: Roy Martin , Clark Peter U. , Duncan Robert A. , Hemming Sidney R.
Published: September 2007

Glacial sedimentary sequences in the north central United States record multiple advances of the Laurentide Ice Sheet (LIS) since ∼2 Ma. Although the tills found in these sequences were deposited by southward flowing glacial lobes, little information is available on the geometry of flow lines in the interior of the LIS during any one glaciation, and the provenance of glacial deposits older than the last ice advance is largely unknown. Systematic changes in the composition of midcontinent tills and other paleogeographic considerations, however, raise the possibility of significant shifts in the trajectory of flow lines feeding the lobes of the southwestern LIS margin. Here we constrain till provenance using40Ar/39Ar ages of individual hornblende and feldspar grains retrieved from tills representing several glaciations since ∼2 Ma. Hornblende grains show40Ar/39Ar ages that indicate erosion of Paleoproterozoic (∼1.7–2.0 Ga) and late Archean (>2.5 Ga) rock sources, whereas feldspar grains show a broad range of Paleoproterozoic ages (∼1.4–2.4 Ga). Dating of hornblende and feldspar minerals in single pebbles suggests that this latter distribution of ages is related to the greater sensitivity of feldspars to thermal resetting during minor tectonic events. Accordingly, the range of40Ar/39Ar ages for the predominant population of Paleoproterozoic hornblende and feldspar grains in our samples is consistent with a source from terrains forming the Churchill province of the Canadian Shield, while the small population of Archean‐age grains likely reflects a source from the southwestern tip of the Archean Superior province that crops out near the study area. These results indicate that midcontinent tills were deposited by ice derived from the northwestern (Keewatin) sector of the LIS. The nearly identical distribution of hornblende and feldspar ages in the till samples identifies the Keewatin ice dome and the related ice flow to the midcontinent as long‐standing features of the LIS throughout the late Pliocene‐Pleistocene glaciations.
Magnetotelluric inversion constrained by seismic data in the Tucumán Basin (Andean Foothills, 27°S, NW Argentina)
Authors: Favetto Alicia , Pomposiello Cristina , Booker John , Rossello Eduardo A.
Published: September 2007

A magnetotelluric (MT) profile and conventional seismic reflection lines are used to characterize the sedimentary basin across the Andean foothills in the Tucumán Plain. This basin is a depocenter surrounded by crystalline basement and filled with a several‐kilometer‐thick sedimentary sequence. Because of the high contrast in electrical resistivity between the basin sedimentary rocks and the crystalline basement, this interface dominates the MT response and masks details of the structure within the sedimentary units. This paper presents a new interpretation of the MT data incorporating structure constraints obtained from a network of seismic lines. Our results indicate that a significantly improved characterization of the conductive horizons within the basin is obtained when resistivity model discontinuities are introduced at the seismic reflectors corresponding to the most important formation boundaries. Improved resistivities of the main formations, Cretaceous‐Miocene and Miocene‐Pliocene, were inferred. The comparison of constrained and unconstrained models constitutes an instructive case study of how controlled MT inversion can improve structure imaging. It also shows that the application of constraints in the inversion process is a worthy option to find a geologically supported model, especially if data misfit shows a marked nonrandom distribution.
A Lagrangian perspective of the tropopause and the ventilation of the lowermost stratosphere
Authors: Berthet G. , Esler J. G. , Haynes P. H.
Published: September 2007

Back trajectories driven by large‐scale analyzed wind fields are used to investigate troposphere to stratosphere transport (TST) in the Northern Hemisphere tropopause region, as well as the surface sources for such transport, defined in terms of the locations where each trajectory last left the atmospheric boundary layer (log pressure height z* < 1 km). The proportion χBL of those trajectories arriving in the tropopause region that have visited the boundary layer within the previous fixed time period (typically 30 days) is determined as a function of each trajectory's final equivalent latitude and potential temperature. For a range of potential temperature surfaces (∼300–380 K), χBL is shown to have a sharp gradient in the extratropics indicative of a partial permeable barrier to transport that can be identified as a “Lagrangian tropopause.” Variations in χBL with equivalent latitude and potential temperature and on seasonal timescales are shown to provide a novel measure for the relative location and permeability of the tropopause barrier. Details such as the presence of a “ventilated layer” in the northern summer extratropical lower stratosphere (∼370–410 K) are clearly apparent. Directly below this layer (340–370 K) the tropopause barrier to transport is shown to be relatively strong, whereas below 340 K it is again more permeable. A distinction can therefore be made between “extratropical” TST that primarily ventilates the lowermost stratosphere below 340 K and “tropical” TST that occurs into the 370–410 K ventilated layer. The boundary layer source regions for extratropical TST are shown to correspond to those regions previously identified as sources for deep frontal uplift in the warm conveyor belt circulations of extratropical cyclones, although elevated regions such as the Himalayan plateau are also seen to be important. Tropical TST has different source regions associated with regions of active deep convection such as the western tropical Pacific and, in the northern summer, the Indian subcontinent. The source regions are, in general, found to be geographically localized, leading to the conclusion that subject to the limitations of the methodology, trace gas emissions in specific regions are substantially more likely to be transported to the lowermost stratosphere than elsewhere. The implications for the assessment of ozone depletion by very short lived halogenated species are mentioned.
Interaction between two subducting plates under Tokyo and its possible effects on seismic hazards
Authors: Wu Francis , Okaya David , Sato Hiroshi , Hirata Naoshi
Published: September 2007

Underneath metropolitan Tokyo the Philippine Sea plate (PHS) subducts to the north on top of the westward subducting Pacific plate (PAC). New, relatively high‐resolution tomography images the PHS as a well‐defined subduction zone under western Kanto Plain. As PAC shoals under eastern Kanto, the PHS lithosphere is being thrusted into an increasingly tighter space of the PAC‐Eurasian mantle wedge. As a result, zones of enhanced seismicity appear under eastern Kanto at the top of PHS, internal to PHS and also at its contact with PAC. These zones are located at depths greater than the causative fault of the disastrous 1923 Great Tokyo “megathrust” earthquake, in the vicinity of several well‐located historical, damaging (M6 and M7) earthquakes. Thus a rather unique interaction between subducting plates under Tokyo may account for additional seismic hazards in metropolitan Tokyo.
Low temperature dependence of electrical resistivity: Implications for near surface geophysical monitoring
Authors: Hayley Kevin , Bentley L. R. , Gharibi M. , Nightingale M.
Published: September 2007

Electrical resistivity imaging surveys are used to monitor variations in pore fluid chemistry and saturation as well as time‐lapse changes. Temperature variations in the near surface can produce larger magnitude changes in electrical conductivity than changes due to slow moving solute plumes or spatial variations in chemistry and soil moisture. Relationships between temperature and electrical conductivity based on previous studies conducted over 25–200°C do not explain 0–25°C laboratory data. A modification to the temperature dependence within a petrophysical model is proposed that may allow general application over this temperature range. An empirical linear approximation of 1.8 to 2.2 percent change in bulk electrical conductivity per degree C is consistent with low temperature electrical conductivity studies and the predictions of the petrophysical model used. This relationship can be used to account for the effect of temperature variations within individual images or time‐lapse difference images.
Auroral arcs as sites of magnetic stress release
Authors: Haerendel Gerhard
Published: September 2007

An analytical model is presented for auroral arcs as the result of a fast release of magnetic shear stresses. The shear stresses are set up by a longitudinal convection that is driven by pressure forces in the outer magnetosphere against the frictional forces exerted in the lower ionosphere. A distorted‐dipole geometry is employed allowing for high plasma beta near the equator. Steep ledges in the radial pressure distribution, extending along the direction of convection, are invoked as the sources of the auroral current sheets. The differential magnetic energy content of these narrow current sheets is released within a few Alfvén transit times by the decoupling of the magnetospheric plasma and field from the ionosphere, owing to the existence of field‐aligned potential drops in the auroral acceleration region, and converted into kinetic energy of the primary auroral particles. A well‐known current‐voltage relation is employed for the formulation of the energy conversion process. This scenario has two important consequences. (1) The loss of magnetic energy creates a concomitant decrease of internal energy of the generator plasma and results in a progression of pressure ledge and auroral current sheet into the more highly stressed magnetic field region. This is the reason for the observed proper motion of auroral arcs with respect to the plasma frame. (2) Plasma and field undergo a rapid stress relief motion along the arc with large but mostly reversible displacements. The net displacement, equivalent to a small S‐shaped contribution to the essentially U‐shaped potential distribution above the auroral arc, is consistent with the transit of the field lines through the progressing current sheet. This scenario is cast into a set of simple relations expressing the key parameters of auroral arcs, such as width, energy flux, potential drop, and proper motion. The main ingredient herein is an auxiliary magnetic perturbation field into which the main properties of the large‐scale current system are condensed. It corresponds to about twice the transverse magnetic perturbation field near the arc and thus to the total shear stresses. Two free parameters are the relative magnitude of the pressure jump at the ledge in the source plasma and the plasma beta. Matching the quantitative results of the relations for the arc properties with observed values suggests pressure jumps of order 10% and beta values between 1 and 5.
Moderate Resolution Imaging Spectroradiometer (MODIS) and Aerosol Robotic Network (AERONET) retrievals during dust outbreaks over the Mediterranean
Authors: Santese M. , De Tomasi F. , Perrone M. R.
Published: September 2007

Moderate Resolution Imaging Spectroradiometer (MODIS)–ocean aerosol products and corresponding Aerosol Robotic Network (AERONET) data retrieved during Sahara dust outbreaks that occurred over the central Mediterranean basin have been analyzed, to contribute to the validation of MODIS retrievals during dust‐loading conditions. It is shown that MODIS aerosol optical depths (AODM) retrieved at 550 nm for window sizes of 50 × 50 km2 centered at different Mediterranean AERONET sites are in satisfactory accordance to corresponding AERONET optical depths (AODA) colocated in space and time: Correlation factor and slope of the linear regression are 0.86 and 1.04, respectively, and 42% of data points are within the prespecified accuracy range. However, the plot of the differences (AODM – AODA) versus AODA has revealed that the differences (AODM – AODA) are almost positive and increase with AODA, and has led assuming that MODIS overestimates AODs mainly during high dust load conditions. The comparison of MODIS‐ocean and corresponding AERONET fine‐mode fractions (ηM and ηA, respectively) colocated in space has revealed that the MODIS‐ocean inversion algorithm overestimates the contribution of fine‐mode particles for dust‐dominated aerosols: (ηM − ηA) difference values vary within the 0.11–0.24 range. In addition, the comparison of MODIS‐ocean and corresponding AERONET volume size distributions has revealed that the latter results are mainly due to the poor sensitivity of the MODIS‐ocean inversion algorithm to the concentration of coarse‐mode particles during dust outbreaks. The frequency distributions of MODIS fine and coarse volume modal radii are found to be rather close to corresponding AERONET frequency distributions.
Midlatitude and high‐latitude N2O distributions in the Northern Hemisphere in early and late Arctic polar vortex breakup years
Authors: Akiyoshi H. , Zhou L. B.
Published: September 2007

Simulated N2O distributions at midlatitudes and high latitudes in the Northern Hemisphere are analyzed in early and late vortex breakup years with the probability distribution function (PDF) technique. The data are from a Center for Climate System Research/National Institute for Environmental Studies (CCSR/NIES) nudging chemical transport model (CTM) for 24 years from 1979 to 2002. Results show that there is a large difference in midlatitude and high‐latitude N2O concentrations on the 600 K isentrope between early and late vortex breakup years. In the early breakup years, the N2O concentration with the maximum area shows low values in the lower stratosphere in the springtime after the vortex breakup. In the late breakup years, the maximum area concentration shows constant high values from the winter to the summer. Our analyses show that the winter and springtime meridional circulation is a main factor for these differences in N2O concentration. In the early breakup years, a larger eddy heat flux causes a stronger winter meridional circulation and a stronger downward advection of low‐N2O concentration air at higher altitudes to the lower stratosphere, which leads to the low values of N2O concentration in the lower stratosphere in late winter and early spring. Inside the Arctic vortex, however, the importance of vertical advection is smaller than or comparable to other processes such as horizontal divergence and subgrid‐scale motions. These results are consistent with the previous studies on tracer distribution, which showed that not only the vertical advection but also the horizontal eddy transport are important for tracer concentration tendency in the polar vortex.
Estimating change in extreme European precipitation using a multimodel ensemble
Authors: Fowler H. J. , Ekström M. , Blenkinsop S. , Smith A. P.
Published: September 2007

Using the results from multimodel ensembles enables the assessment of model uncertainty in present and future estimates of extremes and the production of probabilities for regional or local‐scale change. Six regional climate model (RCM) integrations from the PRUDENCE ensemble are used together with extreme value analysis to assess changes to precipitation extremes over Europe by 2070–2100 under the SRES A2 emissions scenario, investigating the contribution of the formulations of global (GCM) and regional climate models to scenario uncertainty. RCM ability to simulate precipitation extremes is evaluated for a UK case study. RCMs are shown to underestimate 1 day return values but reasonably simulate longer‐duration (5 or 10 day) extremes. A multimodel approach by which probabilities can be produced for regional or local‐scale change in extremes is then developed. A key result is that all RCMs project increases in the magnitude of short‐ and long‐duration extreme precipitation for most of Europe. Individual model projections vary considerably but are independent of changes in mean precipitation. The magnitude of change is strongly influenced by the driving GCM but moderated by the RCM, which also influences spatial pattern. Therefore, when designing future ensemble experiments (1) the number of GCMs should at least equal the number of RCMs and (2) if spatial pattern is important then integrations from different RCMs should be incorporated. For impact studies, both the resolution and number of models in the ensemble will influence projections of change. The use of a multimodel approach therefore provides more robust estimates.
Spatial covariance of water isotope records in a global network of ice cores spanning twentieth‐century climate change
Authors: Schneider David P. , Noone David C.
Published: September 2007

Estimating the spatial extent of past climate changes has been an ongoing challenge for paleoclimatology. For such estimates to be made with confidence, it is important to establish an understanding of the spatial coherence of proxy records during an interval of known climate change. We use water stable isotopes from high‐resolution ice cores and twentieth‐century observations of sea level pressures and sea surface temperatures to assess the covariance among isotopic records and its link to organized patterns of climate variability. Covarying signals in the cores are identified using empirical orthogonal function analysis. Results from regression analysis show that the leading signals are consistent with key climate patterns including the Northern Atlantic Oscillation and Southern Annular Mode and variability in tropical Pacific sea surface temperatures associated with the El Niño–Southern Oscillation. Patterns that have recently been identified in instrumental data, such as positive tropical Pacific SST anomalies associated with the negative phase of the SAM, are evident in the ice cores. These explanations for the variance of stable isotopes are consistent with recent studies using isotope‐enabled general circulation models and provide a physical basis for interpreting the observed isotopic signals. While there is also a global change signal that is evident when analyzing the records collectively, there are some limitations in reconstructing global temperatures due to the geographic coverage of the available records and the current lack of modeling studies to explain the observed global‐scale changes. Still, water stable isotope ratios preserved in ice cores provide a sufficiently rich sampling of large‐scale climate variability that they can be more widely used in physically based paleoclimate reconstructions covering the last millennium and other periods.
Thermal structure of Martian soil and the measurability of the planetary heat flow
Authors: Grott M. , Helbert J. , Nadalini R.
Published: September 2007

We investigate the influence of the external temperature forcing given by seasonal, interannual, and climatic temperature changes on the surface heat flow of Mars and determine how meaningful measurements of the internal planetary heat flow can be obtained. The influence of seasonal temperature changes is found to be efficiently removed if measurements are extended over the period of at least a full Martian year. Interannual variability due to, e.g., eolian‐driven surface albedo changes typically alters the heat flow by less than 15%, although errors may be larger if the soil's thermal conductivity and the albedo variations are both large. Heat flow perturbations caused by long‐term climatic changes are found to stay below 15%. In order to also determine the soil's thermal conductivity with an accuracy of 20% or better, a direct conductivity measurement is required. We conclude that a measurement of the Martian planetary heat flow is possible with an accuracy of 30% or better if measurements are extended over the period of at least a full Martian year and thermal conductivity is directly measured. Temperature sensors should have a precision of 0.1 K, and measurements should be conducted up to a depth of 3–5 m.
Is there a functional correlate of Kv1.5 in the ventricle of canine heart and what would it mean for the use of IKur blockers?
Authors: Wettwer E
Published: September 2007

The cardiac ultrarapid outward current IKur, encoded by KCNA5, is of special pharmacological interest, because it is considered to be atrium‐specific. IKur has therefore become a target in the therapy of atrial tachyarrhythmias. However, the concept of atrium specificity is only valid if a functional IKur current is in fact absent from the ventricle. However, new work has detected a IKur‐like current in canine ventricular myocytes, sensitive to 4‐aminopyridine and suppressed by the IKur blocker DPO‐1, findings that support the existence of a functional ventricular IKur. These indications are, however, indirect and more effort is needed to clarify unequivocally the putative role of an expectedly small IKur component in the ventricle.

British Journal of Pharmacology (2007) 152, 835–837; doi:10.1038/sj.bjp.0707463; published online 17 September 2007
GPR55: a new member of the cannabinoid receptor clan?
Authors: Pertwee R G
Published: September 2007

In this issue of the British Journal of Pharmacology, Ryberg et al. present convincing in vitro evidence that the orphan GPCR, GPR55, is a cannabinoid receptor. GPR55 was activated by a range of plant, synthetic and endogenous cannabinoids and blocked by the non‐psychoactive phytocannabinoid, cannabidiol. Their experiments have revealed several differences between the pharmacology of GPR55 and the established cannabinoid CB1 and CB2 receptors. For example, the CB1 receptor antagonist, AM251, activated GPR55 and the main psychoactive constituent of cannabis, Δ9‐tetrahydrocannabinol, displayed greater efficacy at GPR55 than at CB1 or CB2 receptors. They also compared the distribution of GPR55 and CB1 mRNA in mouse and report that GPR55 couples to Gα13, that it is activated by virodhamine, palmitoylethanolamide and oleoylethanolamide, and that virodhamine displays relatively high efficacy as a GPR55 agonist. Still to be identified are the main roles played by GPR55 in health and disease and any potential therapeutic benefits of activating or blocking this receptor.

British Journal of Pharmacology (2007) 152, 984–986; doi:10.1038/sj.bjp.0707464; published online 17 September 2007
New statistical mechanical model for calculating Kirkwood factors in self-associating liquid systems and its application to alkanol+cyclohexane mixtures
Authors: Vasiltsova Tatiana , Heintz Andreas
Published: September 2007

A new statistical mechanical model for calculating Kirkwood factors in self-associating molecular liquids and their mixtures with nonassociating components has been developed in a consistent way which is based on an extended version of the Flory-Huggins model taking into account chemical association equilibria. The majority of molecular parameters involved into the theory has been fixed by independent quantum mechanical ab initio calculations of associated molecular clusters. The model is also able to predict other thermodynamic mixture properties such as the enthalpy of mixing and also the infrared absorbance of monomer alcohol species as function of concentration. Experimental results of nine alcohol+cyclohexane mixtures taken from the literature have been used to test the new model. The Kirkwood correlation factor gK, the molar enthalpy of mixing HmE, and the monomer IR absorbance can be described simultaneously in excellent agreement with experimental data covering the whole range of mole fraction including temperature dependence of gK, HmE, and the IR absorbance. Two parameters have been adjusted freely for each system. A third parameter for the nonspecific intermolecular dispersion interactions has been adjusted within a limited range of possible values given by physical arguments. The model opens a new way of a more reliable understanding of structures and equilibrium properties of hydrogen bonded systems in the condensed liquid state.
Triplets in extended nematic liquid crystals and polarons in their blends
Authors: Tsoi Wing C. , O’Neill Mary , Aldred Matthew P. , Vlachos Panos , Kelly Stephen M.
Published: September 2007

Photoinduced absorption shows that triplets are the primary photoexcited species in a series of conjugated liquid crystals containing thiophene and fluorene groups. We find that the triplet generation rate can be varied substantially by molecular design. The introduction of extra thiophene groups into the elongated molecules changes the intersystem crossing rate by over two orders of magnitude, while modifying the singlet and triplet energies by only small amounts. This result is attributed to the high spin-orbit coupling constant of sulfur: An increase in the number of sulfur atoms increases the spin-orbit coupling between the singlet and triplet states. These results are relevant to the design of organic light emitting diodes, lasers, and other devices where triplet formation has a major impact on device performance. The molecules are shown to act as effective electron donors when blended with a perylene molecule which acts as an electron acceptor. The electron transfer rate is faster than the singlet lifetime so that the blend shows the efficient charge separation required for a photovoltaic device.
Antenna impedance measurements in a magnetized plasma. I. Spherical antenna
Authors: Blackwell David D. , Walker David N. , Messer Sarah J. , Amatucci William E.
Published: September 2007

The input impedance of a metal sphere immersed in a magnetized plasma is measured with a network analyzer at frequencies up to 1GHz. The experiments were done in the Space Physics Simulation Chamber at the Naval Research Laboratory. The hot-filament argon plasma was varied between weakly (ωce<ωpe) and strongly (ωce>ωpe) magnetized plasma with electron densities in the range 107–1010cm−3. It is observed that the lower-frequency resonance of the impedance characteristic previously associated with series sheath resonance ωsh in the unmagnetized plasma occurs at a hybrid sheath frequency of ωr2=ωsh2+κωce2, where κ is a constant 0.5<κ<1. As seen in previous experiments, the higher frequency resonance associated with the electron plasma frequency ωpe in the unmagnetized plasma is relocated to the upper hybrid frequency ωuh2=ωpe2+ωce2. As with the unmagnetized plasma, the maximum power deposition occurs at the lower frequency resonance ωr.
Simplified mathematical model for the formation of null singularities inside black holes. I. Basic formulation and a conjecture
Authors: Ori Amos , Gorbonos Dan
Published: September 2007

Einstein’s equations are known to lead to the formation of black holes and space time singularities. This appears to be a manifestation of the mathematical phenomenon of finite-time blowup: A formation of singularities from regular initial data. We present a simple hyperbolic system of two semilinear equations inspired by the Einstein equations. We explore a class of solutions to this system which are analogous to static black-hole models. These solutions exhibit a black-hole structure with a finite-time blowup on a characteristic line mimicking the null inner horizon of spinning or charged black holes. We conjecture that this behavior—namely, black-hole formation with blowup on a characteristic line—is a generic feature of our semilinear system. Our simple system may provide insight into the formation of null singularities inside spinning or charged black holes in the full system of Einstein equations.
Invited article: The fast readout low noise camera as a versatile x-ray detector for time resolved dispersive extended x-ray absorption fine structure and diffraction studies of dynamic problems in materials science, chemistry, and catalysis
Authors: Labiche Jean-Claude , Mathon Olivier , Pascarelli Sakura , Newton Mark A. , Ferre Gemma Guilera , Curfs Caroline , Vaughan Gavin , Homs Alejandro , Carreiras David Fernandez
Published: September 2007

Originally conceived and developed at the European Synchrotron Radiation Facility (ESRF) as an “area” detector for rapid x-ray imaging studies, the fast readout low noise (FReLoN) detector of the ESRF [J.-C. Labiche, ESRF Newsletter 25, 41 (1996)] has been demonstrated to be a highly versatile and unique detector. Charge coupled device (CCD) cameras at present available on the public market offer either a high dynamic range or a high readout speed. A compromise between signal dynamic range and readout speed is always sought. The parameters of the commercial cameras can sometimes be tuned, in order to better fulfill the needs of specific experiments, but in general these cameras have a poor duty cycle (i.e., the signal integration time is much smaller than the readout time). In order to address scientific problems such as time resolved experiments at the ESRF, a FReLoN camera has been developed by the Instrument Support Group at ESRF. This camera is a low noise CCD camera that combines high dynamic range, high readout speed, accuracy, and improved duty cycle in a single image. In this paper, we show its application in a quasi-one-dimensional sense to dynamic problems in materials science, catalysis, and chemistry that require data acquisition on a time scale of milliseconds or a few tens of milliseconds. It is demonstrated that in this mode the FReLoN can be applied equally to the investigation of rapid changes in long range order (via diffraction) and local order (via energy dispersive extended x-ray absorption fine structure) and in situations of x-ray hardness and flux beyond the capacity of other detectors.
Hourglass-shaped aperture for cellular electrophysiological study
Authors: Chen Chang-Yu , Liu Kuan-Ting , Jong De-Shien , Wo Andrew M.
Published: September 2007

This work presents a simple process of reflow of melted glass by CO2 laser to form an hourglass-shaped aperture for cellular electrophysiological study. The fabricated aperture proves to be smooth, circular, debris-free, and freshly activated. Two-phase flow simulation illuminates details of the reflow process. The resulting seal resistance quality is well suited to measure ion-channel activities; a seal resistance of 1.9GΩ for PC-12 cell and a typical resistance of 200MΩ for Chinese hamster ovary cells were achieved. This approach can be integrated with microfluidics in a single cell patch or array configuration.
Multibubble plasma production and solvent decomposition in water by slot-excited microwave discharge
Authors: Ishijima T. , Hotta H. , Sugai H. , Sato M.
Published: September 2007

Intense microwaves are injected from a slot antenna into water partly filling a metal vessel. When the vessel is evacuated to saturated vapor pressure (∼5×103Pa) of water, microwave breakdown gives rise to plasmas in many bubbles in the boiling water. Gas bubbling technique enables production of multibubble plasmas in water even at atmospheric pressure. Optical emissions from the exited species are investigated to identify radical species in water. In order to demonstrate application to purification of polluted water, methylene blue and trichlorethylene solution in 8l water were observed to rapidly decrease with multibubble plasma treatment.
Facets and surface relaxation of tetrahexahedral platinum nanocrystals
Authors: Ding Yong , Gao Yifan , Wang Zhong Lin , Tian Na , Zhou Zhi-You , Sun Shi-Gang
Published: September 2007

Platinum tetrahexahedral (THH) nanocrystals have been prepared by an electrochemical treatment of Pt nanospheres supported on glassy carbon by square-wave potential [N. Tian et al., Science 316, 732 (2007)]. In this paper, the shape and facets of the THH nanocrystals have been characterized by transmission electron microscopy. Most of the exposed surfaces are close to {730} facets. Detailed relaxation of the surface atoms has been observed at surface steps. It is anticipated that the high density of atomic steps and kinks is likely related to the enhanced catalytic activity of the THH nanocrystals.
Studies of polymer microring lasers subject to uniaxial stress
Authors: Tulek A. , Vardeny Z. V.
Published: September 2007

The emission spectra of microring lasers fabricated from π-conjugated polymer films casted on nylon microfibers with diameters in the range of 35–90μm were studied upon application of uniaxial stress with strain up to ∼12%. The laser emission spectra substantially change with the applied stress, showing enhanced sensitivity to stress over changes induced in the fiber diameter alone. This is explained as due to the induced change in the polymer refractive index spectrum upon stress, causing an unexpected increase in the refractive index dispersion and, consequently, also in the effective refraction index for lasing at emission wavelengths.
Highly directional emission from photonic crystals with a wide bandwidth
Authors: Li Zhaofeng , Aydin Koray , Ozbay Ekmel
Published: September 2007

The authors numerically and experimentally demonstrated highly directional emission from photonic crystals. This was achieved by first splitting the incident electromagnetic wave into multiple beams using photonic crystal waveguide structures. The beams were then emitted out of the surface of a photonic crystal with the same phase, which resulted in a highly directional radiation pattern. The measured half power beam width was 4.8°, which was in good agreement with the calculated value of 4.1°. In contrast to the traditional beaming structures, their design did not involve gratinglike structures, which resulted in a wider operation bandwidth.
Genotype and age effects on sheep meat production. 4. Carcass composition predicted by dual energy X-ray absorptiometry
Authors: Ponnampalam E. N. , Hopkins D. L. , Dunshea F. R. , Pethick D. W. , Butler K. L. , Warner R. D.
Published: September 2007

This study compares the carcass composition of different genotypes of Australian sheep slaughtered at four ages (110, 236, 412 and 662 days of age, or 4, 8, 14 and 22 months of age). The genotypes used were Poll Dorsetgrowth × Border Leicester Merino (PDg × BLM), Poll Dorsetgrowth × Merino (PDg × M), Poll Dorsetmuscling × Merino (PDm × M), Merino × Merino (M × M) and Border Leicester × Merino (BL × M). Approximately 150 mixed sex animals were slaughtered at each age and the right sides (half carcass) were scanned by dual energy X-ray absorptiometry (DXA) for chemical lean, fat and bone mineral percentages of the carcass. Carcass lean percentage decreased (P < 0.001) across sire groups from Merino to Poll Dorset to Border Leicester at each age, while fatness increased (P < 0.001) in the opposite direction. With age, the magnitude of difference between genotypes for fatness became greater. There was a marked increase (P < 0.01) in ash mineral percentages in M × M and PDg × M genotypes relative to other genotypes in the 14- and 22-month groups. There were no differences (P > 0.1) between PDg × M and PDm × M in either chemical lean or fat percentages at any age but ash mineral percentage was higher in the PDg × M genotype at older ages (P < 0.05). This in turn led to differences in chemical lean : ash mineral content at later ages between PDg × M and PDm × M. Wethers had higher chemical lean (P < 0.05) and lower fat (P < 0.05) percentages in the carcass than ewes at all ages but ash mineral and chemical lean : ash mineral content did not differ between sexes. It was clear that the level of chemical lean or fat or ash mineral composition reached by some genotypes at one age was equivalent to that reached by other genotypes at the next measurement age. Those genotypes that reach a specification at younger ages will be more productive for meat production. Purebred Merino genetics will always be less productive in terms of carcass weight and muscle related productive traits (loin weight, semitendinosus muscle weight, eye muscle area) than BL and PD genetics, but the relative productivity of PD and BL genetics will depend on the traits used in the specification [see also Ponnampalam EN, Hopkins DL, Butler KL, Dunshea FR, Warner RD (2007) Genotype and age effects on sheep meat production. 2. Carcass quality traits. Australian Journal of Experimental Agriculure 47, 1147–1154]. The results suggest that selection for muscling had a greater impact on reducing ash mineral content associated with bone mineral mass than on increasing lean mass in the carcass.
Factors affecting the concentration of short branched-chain fatty acids in sheep fat
Authors: Salvatore L. , Allen D. , Butler K. L. , Tucman D. , Elkins A. , Pethick D. W. , Dunshea F. R.
Published: September 2007

The concentration of short branched-chain fatty acids, specifically 4-methyloctanoic acid (MOA) and 4-methylnonanoic acid (MNA), in subcutaneous fat were determined in five genotypes (Poll Dorset × Border Leicester Merino, Poll Dorset × Merino, Poll Dorsetmuscling × Merino, Merino × Merino, Border Leicester × Merino) of Australian sheep. In total, 264 ewes and wethers, either 8 or 22 months of age, were selected for genotype, age and gender. These animals were sired by 16 rams that were selected for growth based on estimated breeding values (EBVs), except for one group (Poll Dorsetmuscling × Merino), which was selected for muscling based on EBVs. There was a strong relationship between the concentration of MOA and MNA at 8 and 22 months of age. There were no differences between lambs sired by Poll Dorset rams selected for muscling or growth. The 8- and 22-month-old Poll Dorset × Merino sheep had higher levels of MOA and MNA compared with the other genotypes (P < 0.001). At 8 months of age, the wethers had higher levels of MOA and MNA (P < 0.001) than the ewes of the same genotype. There was a strong relationship (P < 0.001) between MOA and MNA and the fat and lean percentage for 22-month-old ewes. Effects of sire, dam and slaughter day (at the same slaughter age) on MOA and MNA were also found. The results suggest that there is good feasibility for selection against animals at risk of possessing higher levels of short branched-chain fatty acids.
Genotype and gender effects on sheep limb bone growth and maturation: selection for loin depth causes bone hypotrophy
Authors: Cake M. A. , Boyce M. D. , Gardner G. E. , Hopkins D. L. , Pethick D. W.
Published: September 2007

This study aimed to compare limb bone growth between offspring of typical crosses used in Australian prime lamb production. Limb bones from sheep of five genotypes – Merino (M × M), Border Leicester sire × Merino (BL × M), Poll Dorset sires selected for growth × Merino (PDg × M), Poll Dorset sires selected for eye muscle depth (PDm × M) × Merino, or second cross (PDg × BLM) – at four time points from 4 to 22 months of age (n = 593) were dissected, measured and weighed. Growth curves were fitted within genotype groups and used to compare (i) overall limb bone growth in terms of length and weight, (ii) differences in allometric growth coefficients for individual bones, (iii) relative limb bone proportions, and (iv) maturity proportion. Results showed two distinct phenotypes in terms of limb bone growth: (i) relative bone hypotrophy of lambs from PDm × M, suggesting that selection for loin depth (PEMD EBV) may be linked with smaller limb size and that their higher muscle : bone ratio may be due to a relative decrease in bone rather than increase muscle weight; and (ii) Merinos were found to have comparable limb length to terminal sire crosses, although distal limb elements were proportionately longer at the expense of the proximal segments that are associated larger muscles. There was a general lack of major differences in bone growth between sheep very different in other production traits, particularly when compared allometrically. Thus, differences in bone growth, proportion or skeletal maturation were greater between ewes and wethers than between these divergent genotypes. PDm × M and BL × M were found to be earlier maturing in terms of limb length, although the bone mineral profile (magnesium content) of PDm × M was suggestive of relative physiological immaturity.
Redescription of Calanoides carinatus (Krøyer) (Copepoda:Calanoida:Calanidae) with a discussion on the status of related species
Authors: Sabatini Marina E. , Ramírez Fernando C. , Bradford-Grieve Janet
Published: September 2007

The marine calanoid Calanoides carinatus s.l. (Krøyer, 1848) is a dominant species in productive coastal upwelling regions on the western coast of Africa, the east coast of South America and off Somalia in the Indian Ocean. However, its first description is very short and based on a single female specimen collected in the south-western Atlantic with ambiguity as to the type locality. As a consequence, it appears that closely related, but undescribed, species are still being identified as C. carinatus. We re-describe and illustrate the adult female and male of C. carinatus s.s. from specimens collected from Brazil. We currently restrict the distribution of this species sensu stricto to the coast of Brazil. Nevertheless, it may be distributed along the whole east coast of South America but confirmation of this conclusion awaits genetic evidence. Additional information is presented on the morphology of C. macrocarinatus (Brodsky, 1972) from off the coast of New Zealand, and Brazilian specimens of C. carinatus are compared with C. macrocarinatus. We discuss the status of Calanoides from other localities and consider the availability of names for species we predict may be differentiated from C. carinatus s.s. in the future.
Effect of arsenate on adsorption of Zn(II) by three variable charge soils
Authors: Liang Jing , Xu Ren-kou , Tiwari Diwakar , Zhao An-zhen
Published: September 2007

The effect of arsenate on adsorption of Zn(II) in 3 variable charge soils (Hyper-Rhodic Ferralsol, Rhodic Ferralsol, and Haplic Acrisol) and the desorption of pre-adsorbed Zn(II) in the presence of arsenate were investigated in this study. Results showed that the presence of arsenate led to an increase in both the adsorption and desorption of Zn(II) in these variable charge soils. It was also suggested that the enhanced Zn(II) adsorption by arsenate was mainly due to the increase in negative surface charge of the soils induced by the specific adsorption of arsenate, and the increase in electrostatically adsorbed Zn(II) was responsible for the increase in the desorption of Zn(II). The effect of arsenate on Zn(II) adsorption primarily depends on the initial concentration of arsenate and Zn(II), the system pH, and the nature of soils. The enhanced adsorption of Zn(II) increased with the increase in the initial concentration of arsenate and the amount of arsenate adsorbed by the soils. The presence of arsenate decreased the zeta potential of soil suspensions and soil IEP and thus shifted the adsorption edge of Zn(II) to a lower pH region. The effect of arsenate on Zn(II) adsorption in these 3 soils followed the order Hyper-Rhodic Ferralsol > Rhodic Ferralsol > Haplic Acrisol, which was consistent to the contents of iron oxides in these soils and the amount of arsenate adsorbed by the soils.
PAS kinase is required for normal cellular energy balance
Authors: Hao Huai-Xiang , Cardon Caleb M. , Swiatek Wojtek , Cooksey Robert C. , Smith Tammy L. , Wilde James , Boudina Sihem , Abel E. Dale , McClain Donald A. , Rutter Jared
Published: September 2007

The metabolic syndrome, a complex set of phenotypes typically associated with obesity and diabetes, is an increasing threat to global public health. Fundamentally, the metabolic syndrome is caused by a failure to properly sense and respond to cellular metabolic cues. We studied the role of the cellular metabolic sensor PAS kinase (PASK) in the pathogenesis of metabolic disease by using
PASK
−/−
mice. We identified tissue-specific metabolic phenotypes caused by
PASK
deletion consistent with its role as a metabolic sensor. Specifically,
PASK
−/−
mice exhibited impaired glucose-stimulated insulin secretion in pancreatic β-cells, altered triglyceride storage in liver, and increased metabolic rate in skeletal muscle. Further,
PASK
deletion caused nearly complete protection from the deleterious effects of a high-fat diet including obesity and insulin resistance. We also demonstrate that these cellular effects, increased rate of oxidative metabolism and ATP production, occur in cultured cells. We therefore hypothesize that PASK acts in a cell-autonomous manner to maintain cellular energy homeostasis and is a potential therapeutic target for metabolic disease.
Hydrogen sulfide attenuates myocardial ischemia-reperfusion injury by preservation of mitochondrial function
Authors: Elrod John W. , Calvert John W. , Morrison Joanna , Doeller Jeannette E. , Kraus David W. , Tao Ling , Jiao Xiangying , Scalia Rosario , Kiss Levente , Szabo Csaba , Kimura Hideo , Chow Chi-Wing , Lefer David J.
Published: September 2007

The recent discovery that hydrogen sulfide (H
2
S) is an endogenously produced gaseous second messenger capable of modulating many physiological processes, much like nitric oxide, prompted us to investigate the potential of H
2
S as a cardioprotective agent. In the current study, we demonstrate that the delivery of H
2
S at the time of reperfusion limits infarct size and preserves left ventricular (LV) function in an
in vivo
model of myocardial ischemia-reperfusion (MI-R). This observed cytoprotection is associated with an inhibition of myocardial inflammation and a preservation of both mitochondrial structure and function after I-R injury. Additionally, we show that modulation of endogenously produced H
2
S by cardiac-specific overexpression of cystathionine γ-lyase (α-MHC-CGL-Tg mouse) significantly limits the extent of injury. These findings demonstrate that H
2
S may be of value in cytoprotection during the evolution of myocardial infarction and that either administration of H
2
S or the modulation of endogenous production may be of clinical benefit in ischemic disorders.