bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Some Vitamins on Lactoperoxidase Enzyme Activity
Authors: Sisecioglu Melda , Cankaya Murat , Ozdemir Hasan
Published: March 2010

Objective: The present paper investigates the in vitro effect of L-ascorbic acid (vitamin C), menadione sodium bisulfate (vitamin K3), and folic acid on purified lactoperoxidase (LPO). Methods: This enzyme was purified from bovine milk by Amberlite CG 50 resin, CM Sephadex C-50 ion-exchange chromatography, and Sephadex G-100 gel filtration chromatography. Results: Rz (A412/A280) value for the purified LPO was found to be 0.8. Lactoperoxidase was purified 20.45-fold with a yield of 28.8 %. Purity of enzyme was checked by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method and a single band was observed. All tested vitamins caused inhibition of the enzyme activity and displayed a competitive type of inhibition mechanism. IC50 values of these three vitamins were 2.03 µM, 0.025 mM, and 0.0925 mM, and the Ki constants were 0.508±0.257 µM, 0.0107±0.0044 mM, and 0.0218±0.0019 mM respectively. Conclusion: The vitamins discussed here displayed inhibition-type competition with LPO enzyme at varying concentrations. Our study showed that L-ascorbic acid exhibited a much higher inhibitory effect at lower concentrations, so it was evidently a more potent inhibitor than other vitamins tested.
Evaluating the Effectiveness of a Weight-loss Program for Perimenopausal Women
Authors: Nestares Teresa , de la Higuera L-F Magdalena , Diaz-Castro Javier , Campos Margarita S. , López-Frías Magdalena
Published: March 2010

In this study, we set out to perform a comparative evaluation of variations in body weight and volume between two groups of women, one young adult and the other perimenopausal, each of which followed a specific weight loss program for the same period of time. The evaluation was based on the weight and volume data obtained from a clinical and anthropometric study. From the anthropometric values obtained, we conclude that in both groups of women, the diet followed was found to be effective in reducing weight and volume, but with respect to time, the weight loss was more noticeable among the younger women, while among the menopausal women it took place more slowly. The difference between the two groups might be explained by diverse hormonal effects, such that metabolism (and therefore caloric expenditure) is higher among the younger women.
Measurement of Zinc Absorption From Meals: Comparison of Extrinsic Zinc Labeling and Independent Measurements of Dietary Zinc Absorption
Authors: Sheng Xiao-Yang , Hambidge K. Michael , Miller Leland V. , Westcott Jamie E. , Lei Sian , Krebs Nancy F.
Published: March 2010

Background: Extrinsic labeling techniques are typically used to measure fractional absorption of zinc (FAZextrinsic) but none have been adequately evaluated. Objective: To compare determination of the quantity of zinc absorbed (TAZextrinisic) using measurements of FAZextrinsic with results of simultaneous determinations of dietary zinc absorbed (TAZmetabolic) that are not dependent on labeling ingested food with an extrinsic tracer (modified metabolic balance technique). Design: 70Zn was administered orally with all meals for 6 consecutive days to 21 healthy, free-living adult women consuming a constant diet. 68Zn and 67Zn were administered intravenously. FAZextrinsic was measured using a dual isotope tracer ratio technique and multiplied by dietary zinc to give TAZextrinsic. TAZmetabolic was determined by addition of net absorption of zinc and endogenous fecal zinc, the latter determined by an isotope dilution technique. Results: TAZextrinsic and TAZnetabolic were 3.0 ± 1.1 mg/day and 3.1 ± 1.1 mg/day respectively, paired t-test p = 0.492. The correlation coefficient for TAZextrinsic and TAZmetabolic was 0.91, and for FAZextrinsic and FAZmetabolic was 0.95. A Bland Altman analysis indicated a bias of 0.07, and the limits of agreement of -0.86 to 1.01 for TAZextrinsic and TAZmetabolic. Conclusion: These results from two independent methods provide reasonable validation of our extrinsic labeling technique for a wide range of composite diets.
Serum 25-hydroxy Vitamin D Levels in Chronic Fatigue Syndrome: a Retrospective Survey
Authors: Berkovitz Saul , Ambler Gareth , Jenkins Michael , Thurgood Sue
Published: March 2010

Introduction: Patients with chronic fatigue syndrome (CFS) may be at risk of osteoporosis due to their relative lack of physical activity and excessive time spent indoors, leading to reduced vitamin D synthesis. We hypothesized that serum 25-OH vitamin D levels are lower in CFS patients than in the general British population. Subjects and methods: We performed a retrospective survey of serum 25-OH vitamin D levels in 221 CFS patients. We compared this to a group of patients attending the hospital for other chronic conditions and to a large British longitudinal survey of 45-year old women, using a variety of appropriate statistical approaches. Results: 25-OH vitamin D levels are moderately to severely suboptimal in CFS patients, with a mean of 44.4 nmol/L (optimal levels >75 nmol/L). These levels are lower and the difference is statistically significant (p<0.0004) than those of the general British population from a recent national survey, but similar to those in patients with other chronic conditions. Conclusions: This data supports the recommendation made in recent NICE guidelines that all patients with moderate to severe CFS should be encouraged to obtain adequate sun exposure and eat foods high in vitamin D. Oral or intramuscular vitamin D supplementation should be considered for those whose levels remain suboptimal.
Estimating uncertainty in N2O emissions from U.S. cropland soils
Authors: Del Grosso S. J. , Ogle S. M. , Parton W. J. , Breidt F. J.
Published: March 2010

A Monte Carlo analysis was combined with an empirically based approach to quantify uncertainties in soil nitrous oxide (N2O) emissions from U.S. croplands estimated with the DAYCENT simulation model. Only a subset of croplands was simulated in the Monte Carlo analysis, which was used to infer uncertainties across the larger spatiotemporal domain. Specifically, one simulation representing dominant weather, soil type, and N inputs was performed for each major commodity crop in the 3000 counties occurring within the conterminous United States. We randomly selected 300 counties for the Monte Carlo analysis and randomly drew model inputs from probability distribution functions (100 iterations). A structural uncertainty estimator was developed by deriving a statistical equation from a comparison of DAYCENT‐simulated N2O emissions with measured emissions from experiments in North America. We estimated soil N2O emission of 201 Gg N from major commodity crops in 2007, with a 95% confidence interval (CI) of 133–304 Gg N. This implies a relative CI of 34% below and 51% above the estimate at the national scale, but the CIs tended to be larger at the regional level, particularly in regions with low emissions. Spatial variability in emissions was driven primarily by differences in N inputs from fertilizer and manure, while temporal variability was driven more by N mineralization rates, which are correlated with weather patterns in DAYCENT. A higher portion of total uncertainty was due to model structure compared to model inputs, suggesting that improvements in model algorithms and parameterization are needed to produce results with higher precision and accuracy.
Fore‐arc basalts and subduction initiation in the Izu‐Bonin‐Mariana system
Authors: Reagan Mark K. , Ishizuka Osamu , Stern Robert J. , Kelley Katherine A. , Ohara Yasuhiko , Blichert‐Toft Janne , Bloomer Sherman H. , Cash Jennifer , Fryer Patricia , Hanan Barry B. , Hickey‐Vargas Rosemary , Ishii Teruaki , Kimura Jun‐Ichi , Peate David W. , Rowe Michael C. , Woods Melinda
Published: March 2010

Recent diving with the JAMSTEC Shinkai 6500 manned submersible in the Mariana fore arc southeast of Guam has discovered that MORB‐like tholeiitic basalts crop out over large areas. These “fore‐arc basalts” (FAB) underlie boninites and overlie diabasic and gabbroic rocks. Potential origins include eruption at a spreading center before subduction began or eruption during near‐trench spreading after subduction began. FAB trace element patterns are similar to those of MORB and most Izu‐Bonin‐Mariana (IBM) back‐arc lavas. However, Ti/V and Yb/V ratios are lower in FAB reflecting a stronger prior depletion of their mantle source compared to the source of basalts from mid‐ocean ridges and back‐arc basins. Some FAB also have higher concentrations of fluid‐soluble elements than do spreading center lavas. Thus, the most likely origin of FAB is that they were the first lavas to erupt when the Pacific Plate began sinking beneath the Philippine Plate at about 51 Ma. The magmas were generated by mantle decompression during near‐trench spreading with little or no mass transfer from the subducting plate. Boninites were generated later when the residual, highly depleted mantle melted at shallow levels after fluxing by a water‐rich fluid derived from the sinking Pacific Plate. This magmatic stratigraphy of FAB overlain by transitional lavas and boninites is similar to that found in many ophiolites, suggesting that ophiolitic assemblages might commonly originate from near‐trench volcanism caused by subduction initiation. Indeed, the widely dispersed Jurassic and Cretaceous Tethyan ophiolites could represent two such significant subduction initiation events.
First observation of a mini‐magnetosphere above a lunar magnetic anomaly using energetic neutral atoms
Authors: Wieser Martin , Barabash Stas , Futaana Yoshifumi , Holmström Mats , Bhardwaj Anil , Sridharan R. , Dhanya M. B. , Schaufelberger Audrey , Wurz Peter , Asamura Kazushi
Published: March 2010

The Sub‐keV Atom Reflecting Analyzer (SARA) instrument on the Indian Chandrayaan‐1 spacecraft has produced for the first time an image of a lunar magnetic anomaly in backscattered hydrogen atoms. The image shows that a partial void of the solar wind, a mini‐magnetosphere, is formed above the strong magnetic anomaly near the Crisium antipode. The mini‐magnetosphere is 360 km across at the surface and is surrounded by a 300‐km‐thick region of enhanced plasma flux that results from the solar wind flowing around the mini‐magnetosphere. The mini‐magnetosphere is visible only in hydrogen atoms with energy exceeding 150 eV. Fluxes with energies below 100 eV do not show corresponding spatial variations. While the high‐energy atoms result from the backscattering process, the origin of the low‐energy component is puzzling. These observations reveal a new class of objects, mini‐magnetospheres, and demonstrate a new observational technique to study airless bodies, imaging in backscattered neutral atoms.
Local effects of climate change over the Alpine region: A study with a high resolution regional climate model with a surrogate climate change scenario
Authors: Im E.‐S. , Coppola E. , Giorgi F. , Bi X.
Published: March 2010

We discuss a surrogate climate change (SCC) simulation over the Alpine region with a high resolution regional climate model (RegCM3) using a fine scale sub‐grid land surface representation. Multi‐year simulations are completed with an imposed illustrative 3K warming on the forcing large scale meteorological conditions and on the sea surface temperatures in the interior domain. The corresponding relative humidity is kept constant, which results in an increase of atmospheric moisture. We find that in the winter season precipitation increases consistently with the SCC approach, with a significant dependence on topographical elevation. Other components of the surface energy and water budgets also show a marked elevation dependency, mostly tied to changes in snow cover. In summer, contrary to what might be expected from the SCC forcing, precipitation decreases over the Alpine mountain chain. This is due to a local surface‐atmosphere feedback mechanism involving reduced snow cover and soil moisture at the beginning of summer. Our results suggest that over the Alps during summer local feedbacks related to the surface energy and water budgets are important factors in determining the precipitation response to global warming. This result might extend to other mid‐latitude mountainous areas.
Plasma refilling rates for L = 2.3–3.8 flux tubes
Authors: Obana Yuki , Menk Frederick W. , Yoshikawa Ichiro
Published: March 2010

Measurements of the eigenfrequency of geomagnetic field lines can provide information on the plasma mass density near the equatorial plane of the magnetosphere. Data from an extended meridional array of ground magnetometers therefore allow the radial density distribution, and its temporal variation, to be remotely monitored. Using cross‐phase analysis of magnetometer array data, we determined the equatorial mass density during three moderate geomagnetic storms in March 2004 and June and April 2001. In each case the field line eigenfrequency increased markedly, corresponding to reductions in mass density and indicating that the plasmapause moved earthward and these flux tubes were depleted. We then measured the rate at which these flux tubes were refilled to prestorm levels. This took 2–3 days for L = 2.3 flux tubes, 3 days at L = 2.6, and over 4 days for L > 3.3. Plasmaspheric refilling progressed with a clear diurnal variation associated with linearly increasing plasma density in the daytime and decreasing plasma density at nighttime. The daytime increases in plasma mass density related to refilling rates ranging from ∼250 to ∼13 amu cm−3 h−1 over L = 2.3–3.8. The resultant upward plasma flux at the 1000 km level was in the range 0.9–5.2 × 108 amu cm−2 s−1. We also determined the daily averaged refilling rate to be ∼420 amu cm−3 d−1 at L = 2.9–3.1, including the nighttime downward flux. By comparison with Imager for Magnetopause‐to‐Aurora Global Exploration–EUV and VLF whistler data we were able to estimate the plasma composition and found the O+ proportion was of order 3%–7% at L = 2.3 and 6%–13% at L = 3.0.
Systematic evaluation of ground and geostationary magnetic field predictions generated by global magnetohydrodynamic models
Authors: Pulkkinen A. , Rastätter L. , Kuznetsova M. , Hesse M. , Ridley A. , Raeder J. , Singer H. J. , Chulaki A.
Published: March 2010

In this work a systematic evaluation of ground and geostationary magnetic field predictions generated by a set of global magnetohydrodynamic (MHD) models is carried out. The evaluation uses four geospace storm events and ground magnetometer station and geostationary GOES data for comparisons between model output and observations. It is shown that metrics analysis of two different geospace parameters, i.e., geostationary and ground magnetic field, show surprising similarities, although the parameters reflect rather different properties of geospace. More specifically, increasing the spatial resolution and inclusion of more realistic inner magnetospheric physics successfully made the model predictions by the BATS‐R‐US model more accurate. Furthermore, while the OpenGGCM model had a tendency to have larger differences to observations than BATS‐R‐US in terms of the prediction efficiency, the model provided more accurate representation of the observed spectral characteristics of the ground and geostationary magnetic field fluctuations.
Magnetospheric modes and solar wind energy coupling efficiency
Authors: Pulkkinen T. I. , Palmroth M. , Koskinen H. E. J. , Laitinen T. V. , Goodrich C. C. , Merkin V. G. , Lyon J. G.
Published: March 2010

Using observations and two different global MHD simulations, we demonstrate that the solar wind speed controls the magnetospheric response such that the higher the speed, the more dynamic and irregular is the magnetospheric response. For similar level of driving solar wind electric field, the magnetospheric modes can be organized in terms of speed: Low speed produces steady convection events, intermediate speeds result in periodic sawtooth oscillations, and high speeds drive large geomagnetic storms. We show that the control parameter of energy transfer and coupling is the electric field along the large‐scale X line. We demonstrate using global MHD simulations that for slowly varying interplanetary magnetic field (IMF), the reconnection line is tilted approximately by an angle θ/2, where θ is the IMF clock angle. Then, for clock angles away from northward, the magnetospheric energy entry and response scale with the electric field along the reconnection line (EPAR), rather than the traditionally used EY. If we define the energy coupling efficiency as response/EPAR, we can show it to be independent of the IMF clock angle and only weakly dependent on the solar wind dynamic pressure. These results demonstrate the ability of the localized reconnection line to control the energy input through the entire magnetopause.
An elastic plate model for interseismic deformation in subduction zones
Authors: Kanda Ravi V. S. , Simons Mark
Published: March 2010

Geodetic observations of interseismic surface deformation in the vicinity of subduction zones are frequently interpreted using simple kinematic elastic dislocation models (EDM). In this theoretical study, we develop a kinematic EDM that simulates plate subduction over the interseismic period (the elastic subducting plate model (ESPM)) having only 2 more degrees of freedom than the well‐established back slip model (BSM): an elastic plate thickness and the fraction of flexural stresses due to bending at the trench that are released continuously. Unlike the BSM, in which steady state deformation in both plates is assumed to be negligible, the ESPM includes deformation in the subducting and overriding plates (owing to plate thickness), while still preserving the correct sense of convergence velocity between the subducting and overriding plates, as well as zero net steady state vertical offset between the two plates when integrated over many seismic cycles. The ESPM links elastic plate flexure processes to interseismic deformation and helps clarify under what conditions the BSM is appropriate for fitting interseismic geodetic data at convergent margins. We show that the ESPM is identical to the BSM in the limiting case of zero plate thickness, thereby providing an alternative motivation for the BSM. The ESPM also provides a consistent convention for applying the BSM to any megathrust interface geometry. Even in the case of nonnegligible plate thickness, the deformation field predicted by the ESPM reduces to that of the BSM if stresses related to plate flexure at the trench are released either continuously and completely at shallow depths during the interseismic period or deep in the subduction zone (below ∼100 km). However, if at least a portion of these stresses are not continuously released in the shallow portion of the subduction zone (via seismic or aseismic events), then the predicted surface velocities of these two models can differ significantly at horizontal distances from the trench equivalent to a few times the effective interseismic locking depth.
Indirect validation of tropospheric nitrogen dioxide retrieved from the OMI satellite instrument: Insight into the seasonal variation of nitrogen oxides at northern midlatitudes
Authors: Lamsal L. N. , Martin R. V. , van Donkelaar A. , Celarier E. A. , Bucsela E. J. , Boersma K. F. , Dirksen R. , Luo C. , Wang Y.
Published: March 2010

We examine the seasonal variation in lower tropospheric nitrogen oxides (NOx = NO + NO2) at northern midlatitudes by evaluating tropospheric NO2 columns observed from the Ozone Monitoring Instrument (OMI) satellite instrument with surface NO2 measurements (SouthEastern Aerosol Research and Characterization and Air Quality System) and current bottom‐up NOx emission inventories, using a global model of tropospheric chemistry (GEOS‐Chem). The standard (SP) and DOMINO (DP) tropospheric NO2 column products from OMI exhibit broadly similar spatial and seasonal variation, but differ substantially over continental source regions. A comparison of the two OMI tropospheric NO2 products with in situ surface NO2 concentrations and bottom‐up NOx emissions over the southeast United States indicates that annual mean NO2 columns from the DP are biased high by 21%–33% and those from the SP are biased high by 27%–43%. The bias in SP columns is highly seasonal, 67%–74% in summer compared with −6% to −1% in winter. Similar seasonal differences exist between top‐down and bottom‐up NOx emission inventories over North America, Europe, and East Asia. The air mass factor largely explains the observed seasonal difference between the DP and SP, and in turn the seasonal SP bias. We develop a third product (DP_GC) using averaging kernel information from the DP and NO2 vertical profiles from GEOS‐Chem. This product reduces to 5%–21% the annual mean bias over the southeast United States. We use the seasonal variation in the DP_GC to estimate the seasonal variation in the lifetime of lower tropospheric NOx against oxidation to HNO3 over the eastern United States. The effective NOx lifetime at OMI overpass time (early afternoon) ranges from 7.6 h in summer to 17.8 h in winter, consistent within 3 h of the simulated lifetime. GEOS‐Chem calculations reveal that the seasonal variation in OMI NO2 columns largely reflects gas‐phase oxidation of NO2 in summer with an increasing role for heterogenous chemistry in winter.
Statistical modeling of daily urban water consumption in Hong Kong: Trend, changing patterns, and forecast
Authors: Wong Jefferson See , Zhang Qiang , Chen Yongqin David
Published: March 2010

This study attempted to address statistical properties and forecast of daily urban water consumption in Hong Kong from 1990 to 2007. A statistical model was formulated to differentiate the effects of five factors on water use, i.e., trend, seasonality, climatic regression, calendar effect, and autoregression. The postulate of the statistical model is that total water use is made up of base, seasonal, and calendrical water use. Daily urban water consumption in Hong Kong from 1990 to 2001 was modeled and the developed statistical model explains 83% of the variance with six factors: trend (8%), seasonality (27%), climatic regression (2%), day‐of‐the‐week effect (17%), holiday effect (17%), and autoregression (12%). The model was further validated using an independent data set from 2002 to 2007, yielding a R2 of 76%. The results indicated good performance of the developed statistical model in depicting the temporal variations of the urban water use in Hong Kong, offering an improved insight into urban utilization of water resources and acting as the theoretical support for effective urban water resource management in Hong Kong under the changing environment.
Differences in the DNA replication of unicellular eukaryotes and metazoans: known unknowns
Authors: Errico Alessia , Costanzo Vincenzo
Published: March 2010

Although the basic mechanisms of DNA synthesis are conserved across species, there are differences between simple and complex organisms. In contrast to lower eukaryotes, replication origins in complex eukaryotes lack DNA sequence specificity, can be activated in response to stressful conditions and require poorly conserved factors for replication firing. The response to replication fork damage is monitored by conserved proteins, such as the TIPIN–TIM–CLASPIN complex. The absence of this complex induces severe effects on yeast replication, whereas in higher eukaryotes it is only crucial when the availability of replication origins is limiting. Finally, the dependence of DNA replication on homologous recombination proteins such as RAD51 and the MRE11–RAD50–NBS1 complex is also different; they are dispensable for yeast S‐phase but essential for accurate DNA replication in metazoans under unchallenged conditions. The reasons for these differences are not yet understood. Here, we focus on some of these known unknowns of DNA replication.
Tame affairs: domesticated transposase and domestic pigs
Authors: Volff Jean‐Nicolas
Published: March 2010

Long thought to be genomic junk, domesticated transposons have turned out to be an incredible source of new genes. Two studies—one this issue of EMBO reports—show that a domesticated hAT transposase is a transcriptional repressor of IGF2 that regulates muscle growth and has over 1,200 additional putative targets in the mammalian genome.
NF‐κB: no longer an island, but a piece of a continent
Authors: Natoli Gioacchino
Published: March 2010

The Keystone meeting on NF‐κB in Inflammation and Disease held in January covered several aspects of NF‐κB regulation. Many new concepts emerged in signalling, transcriptional control and the involvement of NF‐κB in disease, particularly cancer.
Biological robotics and nanorobotred cells: Characterization and applications
Authors: Sharma Rakesh , Kwon Soonjo , Chen Ching
Published: March 2010

In human body, nanorobot-like red blood cells get exposed to human body fluids and many physico-chemical changes inside while these nanorobots (fullerene structure coated hemoglobin embedded iron inorganic elements) remain safe and perform killer action against bacteria or virus. We propose this killer action as ‘nanorobot driven nanomedical treatment’ to combat a bacterial or viral infection. The red cells also act as imaging agent due to oxygen binding character. Our experiments were focused on the application of nanorobot (red cells) to make them immune resistant against viruses and making them as useful contrast agents in magnetic resonance imaging use based on their behavior in nanomagnetic fields. It consists of an injection of perhaps a few cubic centimeters of nano-sized nanorobots suspended in specific pH fluid (probably a water/saline suspension). The typical therapeutic concentration was up to 1-10 trillion (1 trillion = 10 raise to power 12) individual nanorobots, although in some cases treatment only require a few million or a few billion individual nanodevice-like red cells to be injected. Each nanorobot cell was on the order of perhaps 0.2 micron up to perhaps 0.3 microns in diameter e.g. artificial mechanical red cell floating along in the bloodstream. Nanorobots intended to travel through the bloodstream to their target will probably be 500-3000 nanometers. New technology of ‘passive diamond exteriors’ may turn out to be ideal to make immunoresistant nanorobot red cells against opsonization. Since nanorobot red cells metabolize local glucose and oxygen for energy, they are potential contrast agents for 13C-MRI, ultrasound imaging and physiological or fMRI. We believe the near possibility of travelling nanorobot carrier cells holding nanocomputer CPU working at the rate of 10 teraflops (10 raise to the power 13 floating-point operations per second) as nanomedicine robot devices. Nanorobot red cells in medical applications may be used in the form of red cells coated with diamond or diamondoid/fullerene nanocomposites in presence of inorganic elements like hydrogen, sulfur, oxygen, nitrogen, fluorine, silicon etc. for special purpose in nanoscale gears.
Localized heating induced chemical vapor deposition for one-dimensional nanostructure synthesis
Authors: Sosnowchik Brian D. , Lin Liwei , Englander Ongi
Published: March 2010

Localized heating has emerged as a viable technique for the site specific synthesis of one-dimensional (1D) nanostructures. By localizing the heat source, the extent of chemical vapor deposition synthesis reactions can be confined to well-defined, microscale regions. Resistive heating has been extensively used to realize highly localized regions of elevated temperature while maintaining a microelectronics-compatible thermal environment elsewhere. Other localized heating methods are being pursued as well. Overall, the approach is simple, flexible, and robust, and offers unique opportunities in 1D nanostructure synthesis, characterization, and integration. Herein, the recent progress of these techniques is reviewed and discussed.
Surface-potential decay of biased-probe contact-charged amorphous polymer films
Authors: Knorr Nikolaus , Rosselli Silvia , Nelles Gabriele
Published: March 2010

We have investigated the decay of scanning Kelvin probe force microscopy (KPFM) and electric force microscopy (EFM) signals from biased-probe contact-charged films of three different amorphous polymers representing wide-ranging water absorption capabilities. The surface-potential decay (SPD) has been measured by repeatedly scanning the charge pattern as a function of dissipation time t while varying the relative humidity (RH), the film thickness d, the temperature, the charging voltage, and the load on the scanning probe. Whereas increases in KPFM and EFM peak widths are appreciable only in the long run, the decay in the peak heights is rapid at the beginning and then strongly slowing down with time. Peak heights can be approximated for t<1 hour by power laws of negative exponents (−β), with 0<β<0.5 in dry conditions. β increases for thinner films and when scanning with higher probe loads. Raising the humidity or heating to temperatures well below the glass transition temperature of the polymer considerably increases β, with much stronger impacts for polymers with a higher water uptake capability. From the findings, we conclude that ionic charge carriers are trapped by the charge injection process in the volume of the polymers at low depths. A main contribution to SPD is by drift of the ions in their own space-charge field, mutually repelling each other and being attracted by their mirror charge in the grounded back electrode. Lateral drifts for small t are not resolved, increases in peak widths for t⪢1 h are predominantly due to increased probe—charge carrier distances. We interpret the power law approximation in terms of dispersive transport theory. We approximate trap-controlled apparent mobilities μ from isothermal KPFM peak height data, taken within a few minutes after charging, by a linear and a hyperbolic SPD model. Both models yield μ≈10−14 cm2/(V s) for thin films (d≈50 nm) in dry conditions. For mobilities derived similarly from isohumid measurements series, we find an exponential increase as a function of RH%. We furthermore suggest that two more mechanisms contributing to SPD are: first, by potential shielding of charge carriers by water dipoles, and second, in an indirect manner, by diffusion of injected water.
Lattice template effect on epitaxial γ-Fe2O3 films prepared by metal organic deposition
Authors: Manago Takashi , Sonobe Tomoyuki , Yamaguchi Iwao , Takano Fumiyoshi
Published: March 2010

The preparation of γ-Fe2O3 epitaxial films by metal organic deposition and the magnetic properties of the resultant films were studied using two different substrates; MgO and Si. The film deposited on a Si substrate had a polycrystalline corundum structure and did not exhibit magnetic properties, and was thus concluded to be antiferromagnetic α-Fe2O3. However, the film deposited on a MgO substrate had the epitaxial spinel structure and exhibited ferromagnetism with a magnetic moment of approximately 2 μB at low temperature, and was thus concluded to be ferromagnetic γ-Fe2O3. The films and their characteristics are largely dependent on the substrates employed, even when the same preparation conditions are used, such as annealing temperature and atmosphere. The lattice template effect of the substrate is important, especially for the materials with characteristics that are largely dependent on their lattice structure.
Short piston-cylinder pressure cells based on Ni–Cr–Al cylinders and their application to fragile materials
Authors: Taniguchi Hiromi , Takeda Sunao , Satoh Ryosuke , Taniguchi Arisa , Komatsu Hiroaki , Satoh Kazuhiko
Published: March 2010

In this decade, the performance of piston-cylinder pressure cells has been drastically improved by using robust materials such as nickel-chromium-aluminum and cobalt-nickel-chromium-molybdenum alloys to construct the inner cylinders. In this article, we present several experimental techniques for carrying out resistivity measurements under high pressure by applying the piston-cylinder devices based on the nickel-chromium-aluminum cylinders to fragile materials such as organics. These techniques are, in principle, applicable to measurements on any solid-state conductor. First, we introduce the construction of our piston-cylinder cells including two kinds of wired platforms for transport measurements. Second, we describe the construction of the platforms and the method of introducing the samples. After reporting test results for conventional materials such as ammonium fluoride, bismuth, and tellurium, lastly, we present examples of the successful application of our method to organic materials.
Thermal annealing of arsenic tri-sulphide thin film and its influence on device performance
Authors: Choi Duk-Yong , Madden Steve , Bulla Douglas , Wang Rongping , Rode Andrei , Luther-Davies Barry
Published: March 2010

Arsenic tri-sulphide (As2S3) thin film waveguides have been used successfully as nonlinear optical devices for all-optical signal processors. For such devices, low propagation loss is vital if high performance is to be obtained. In this study, thermal annealing was employed not only to stabilize the physical properties of the films, but also to reduce the sources of light attenuation in the as-deposited material. Here we investigated heat-induced changes to the microstructure and optical properties of As2S3 thin films and, based on this information, determined the best annealing conditions. The refractive index of the films rises with annealing due to thermal densification and increased heteropolar bond density. The growth of surface roughness and thermal stress in the film, however, limits the annealing temperature to ∼130 °C. We fabricated and analyzed waveguides produced from as-deposited and annealed films and found that the propagation loss of the guides dropped by ∼0.2 dB/cm as a result of appropriate annealing. Rayleigh scattering and absorption from defects associated with phase separation, homopolar bonds, voids, and dangling bonds in the as-deposited film are shown to contribute to the higher light attenuation in unannealed films.
Pendulum, elliptic functions, and relative cohomology classes
Authors: Françoise J.-P. , Garrido P. L. , Gallavotti G.
Published: March 2010

Revisiting canonical integration of the classical pendulum around its unstable equilibrium, normal hyperbolic canonical coordinates are constructed and an identity between elliptic functions is found whose proof can be based on symplectic geometry and global relative cohomology. Alternatively it can be reduced to a well known identity between elliptic functions. Normal canonical action-angle variables are also constructed around the stable equilibrium and a corresponding identity is exhibited.
A fractional calculus of variations for multiple integrals with application to vibrating string
Authors: Almeida Ricardo , Malinowska Agnieszka B. , Torres Delfim F. M.
Published: March 2010

We introduce a fractional theory of the calculus of variations for multiple integrals. Our approach uses the recent notions of Riemann–Liouville fractional derivatives and integrals in the sense of Jumarie. The main results provide fractional versions of the theorems of Green and Gauss, fractional Euler–Lagrange equations, and fractional natural boundary conditions. As an application we discuss the fractional equation of motion of a vibrating string.
Laser soft marking on silicon wafer
Authors: Khoong L. E. , Lam Y. C. , Zheng H. Y. , Chen X.
Published: March 2010

A laser soft marking technique is developed for laser markings on a silicon wafer. Due to negligible surface modification, the laser soft wafer markings are invisible by naked eyes under room condition and are undetectable using sophisticated instruments. However, these laser markings are found to be visible to naked eyes through a differential condensation of water droplets on the laser-marked and unmarked silicon surfaces. To understand this phenomenon, a model is established to study the condensation of water droplets on laser-marked and unmarked silicon surfaces. Experimental observations and simulation results indicate that the laser soft marking could have modified the silicon surface with a thin polycrystalline silicon layer which has a much lower conductivity than the crystalline silicon. In addition, this thin layer exhibits a thermal conductivity which is approximately two orders of magnitude lower than that of its equivalent bulk material. As a result, heat transfer on the laser-marked silicon surface is much lower than the crystalline silicon and thus makes these laser soft markings easily visible visually under condensation.
Note: Studies on target placement in TE111 cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose
Authors: Selvakumaran T. S. , Baskaran R. , Singh A. K. , Sista V. L. S. Rao
Published: March 2010

X-ray source based on electron cyclotron resonance principle has been constructed using TE111 cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE111 cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150–500 W.
Electronic structure of SnxGe1−x alloys for small Sn compositions: Unusual structural and electronic properties
Authors: Chibane Y. , Ferhat M.
Published: March 2010

The full potential augmented plane wave plus local orbital method using the local density approximation within the framework of density functional theory is applied to investigate structural, electronic, and thermodynamic properties of SnxGe1−x alloys for small Sn compositions (x=0.0625, 0.125, 0.1875, and 0.25). For the structural properties, we found strong deviation from Vegard’s law for the variation in the lattice parameter, moreover, this deviation is found positive as found experimentally. This feature is in direct contrast with conventional IV-IV alloys, were the deviation of the variation in the lattice parameter from Vegard’s law is generally weak and negative. The calculated bond lengths of Sn–Ge, also show significant departures of bond lengths from the virtual crystal approximation (VCA). The calculations confirm a strong band gap reduction in Ge. For small Sn incorporation, the calculated optical band gap bowing (i.e., bowing of the direct band gap) is found strongly composition dependent. For small Sn composition (x=0.0625), we found a strong optical band gap bowing of 2.9 eV, in very good agreement with the measured values at low Sn composition of 2.8 eV of [He and Atwater, Phys. Rev. Lett. 79, 1937 (1997)] and 2.84 eV of Pérez Ladrón de Guevara et al. [Appl. Phys. Lett. 91, 161909 (2007)]. For small composition regime (0<x<0.1875) we found an optical band gap bowing of 1.9 eV again in good agreement with the measured value of 1.94 eV at room temperature. For the indirect band gap at L point, a bowing of 0.90 eV is found in agreement with the measured value of 1.23 eV. Regarding the local environment of the Sn atoms, we notice that the clustering has a strong influence on the direct band gap; the maximal (minimal) Sn-clustered configurations have the highest (lowest) band gap. From a detailed analysis of the physical origin of the optical band gap bowing, we found that the relative contribution of the three components [volume deformation (VD), charge exchange, and strain] show that the most significant effect is the structural one (relaxation and VD) due to the large mismatch of the lattice constants of Sn and Ge (∼15%). Our results show that the change from indirect to direct band gap occurs at ∼0.105 in perfect agreement with the measured value of 0.1. Our value for the critical composition is found lower than the value predicted by the VCA (∼0.20). Finally, we found that the instability of SnGe alloys is basically dominated by a strong charge transfer between Sn and Ge, leading a positive chemical energy, this instability is amplified by positive strain energy. The relatively weak negative structural energy is not enough to stabilize the SnGe alloys.
Second-harmonic generation in one-dimensional metal gratings with dual extraordinary transmissions
Authors: Kang Ming , Li Yongnan , Lou Kai , Li Si-Min , Bai Qiang , Chen Jing , Wang Hui-Tian
Published: March 2010

We investigate the enhanced second-harmonic generation (SHG) in nonlinear metal gratings with simultaneously extraordinary optical transmissions (EOTs) for the fundamental and the second-harmonic wavelengths, i.e., dual EOTs. We show that the strongly temporal and spatial dispersions at Wood’s anomalies, the asymmetry in the grating structure and the intrinsic dispersion of the media are of great importance in achieving dual-EOT SHG. Metal gratings with dual EOTs are present and the maximum enhancement on SHG is around 20. Weak points of dual-EOT SHG, potential improvement and future applications are discussed.
Nonlinear optical phase shift obtained from two-level atoms confined in a planar microcavity
Authors: Oka Hisaki , Fujiwara Hideki , Takeuchi Shigeki , Sasaki Keiji
Published: March 2010

We investigate the nonlinear optical phase shift obtained from a thin atomic layer confined in a distributed Bragg reflector (DBR) microcavity with reflection geometry. The optical response of the atom-cavity system is numerically analyzed using finite-difference time-domain method with the optical Bloch equations. The optimal position of atomic layer, at which a maximal phase shift of π is realized, drastically changes with the quality factor Q of the cavity. We show that for high Q the maximal phase shift of π can be obtained anywhere in the cavity field independently of atomic layer position. This result is in contrast to that obtained from a one-dimensional atom model in the limit of bad cavity, where a maximal phase shift of π is obtained only at the antinode of the cavity field. We also show that the independence of phase shift on atom position realized in high-Q regime is due to an interference effect in the surface layers of the DBR cavity.
Effects of minor addition on glass forming ability: Thermal versus elastic criteria
Authors: Zong H. T. , Ma M. Z. , Wang Li-Min , Liang S. X. , Liu R. P.
Published: March 2010

The effect of partial substitution of Zr by Al in Zr35−xTi30Cu7.5Be27.5Alx (x≤10) alloys on the glass forming ability (GFA) is studied. The thermal and the elastic criteria in evaluating the GFA of the alloys are examined. The calorimetric quantities are measured to determine the width of the supercooled liquid region ΔTx and γ indexes. Parallel studies are performed to measure the elastic moduli with the emphasis of the ratio of the shear to the bulk modulus G/B. The addition of Al is found to have remarkable influence on the GFA of the alloys. While ΔTx and γ decrease with the deterioration of the GFA, G/B is observed to decrease as well, contrasting with the general tendency among various glass forming metallic systems. The thermal and elastic criteria of GFA are discussed.
Summer-Autumn home range and habitat use of the Hastings River mouse Pseudomys oralis (Rodentia: Muridae).
Authors: Meek P. D. , Radford S. L. , Tolhurst B. L.
Published: March 2010

Individuals from a population of Hastings River mouse (Pseudomys oralis) were radio tracked in a short-term investigation of home range, habitat use and movement patterns in Marengo State Forest on the northern tablelands of New South Wales. Results were assessed in the context of conservation and management of this threatened species and compared to research in other parts of the species? distribution. The mean summer-autumn home range (Minimum Convex Polygon) of five animals that met the home range asymptote was 0.78�ha, the minimum home range for fourteen mice was 0.72�ha, while median home range for males was 0.8�ha and females 0.53�ha. There was no significant difference in home range size between sexes. Habitat data indicated that fallen logs, including tree head and butt residue following logging, are important refuge and nest sites, even when rocks and hollows are available. A diversity of fern and other ground plant species (including grasses) was important habitat for the species, microhabitat consisting predominantly of sedge and rush was not favoured.
Dunnarts from Boullanger Island: new evidence and reassessment of a taxonomic issue with resource implications.
Authors: Start A. N. , Moro D. , Adams M. , Bencini R.
Published: March 2010

Crowther et al. (1999) described an island population of an Australian dasyurid marsupial, Sminthopsis griseoventer, as a new subspecies on molecular (allozyme) and morphological grounds despite a previously published, contradictory genetic study and evidence of sympatry with its mainland conspecific. The legitimacy of this taxonomic arrangement has implications for the allocation of scarce management resources because the new taxon could be considered 'Critically Endangered'. Samples of the original tissues from which the molecular data cited by Crowther et al. were obtained no longer exist. Therefore, salient components of that work were rerun with fresh tissue and the results used to reassess evidence that the island population warrants recognition as a subspecies. We conclude that neither the molecular nor the morphological data supports differentiation at taxonomic or evolutionarily significant levels. Nevertheless, there is a good case for recognising the island population as an important management unit. This case study emphasises the importance of sound taxonomy determined by macro and molecular characters as a prerequisite to allocating resources for conservation.
Breeding and longevity in captive Australian sea lions Neophoca cinerea at zoos and aquaria in Australia: 1965-2003.
Authors: Ling J. K. , Atkin C. , Barnes A. , Fischer A. , Guy M. , Pickering S.
Published: March 2010

Australian sea lions (Neophoca cinerea) are known to have been kept in aquaria and zoos in Australia since 1965. During that time at least 41 births were recorded, of which 19 were in Adelaide, 15 at Adelaide Zoo and 4 at Marineland of South Australia. The mean interval between successive births in Adelaide was 538.9 � 9.5 days (18.0 months; n = 10) and the mean assumed pregnancy period, including embryonic diapause, was 536.0 � 11.4 days (17.9 months; n = 9). The mean interval between parturition and presumed successful mating was 8.4 � 1.6 days (n = 5). Births occurred in all months except January, June, August and December. Figures for New South Wales and Queensland establishments are too small and scattered over time for any pregnancy periods or birth intervals to be determined. Likewise, latitudinal differences, if any, were not evident, because of the paucity of data from these more northerly places. One female at the Adelaide Zoo produced 8 pups between 1986 and 1997; she is still alive after 22 years in captivity. The youngest known-age (captive-born) female was 4 years, 8 months old when she gave birth to her first pup; and the oldest female in captivity to give birth to a pup was aged approximately 21 years, 8 months. The longest recorded captive period for a female was more than 25 years by 31 December 2003, and for a male it was 21 years, 11 months. A captive-bred female was still alive after 18 years, 2 months, 24 days; another such female died aged 18 years, 2 months, 18 days. These life spans appear to be similar to those that meagre data suggest for tagged N. cinerea in the wild.