bluuebunny/crossref_metadata_2025 huggingface dataset:
Validity of carbohydrate, glycaemic index and glycaemic load data obtained using a semi-quantitative food-frequency questionnaire
Authors: Barclay Alan Winston , Flood Victoria Mary , Brand-Miller Jennie Cecile , Mitchell Paul
Published: October 2007

Objective

To assess the ability of a food-frequency questionnaire (FFQ) to rank Australians according to their intake of total carbohydrate, sugar, starch, fibre, glycaemic index (GI) and glycaemic load (GL).

Design

Cross-sectional sample from a population cohort.

Setting

Two postcode areas west of Sydney, Australia.

Subjects

From 1992 to 1994, a total of 2868 older Australians provided dietary data using a 145-item Willett-derived FFQ. A representative sub-sample of 78 subjects completed three 4-day weighed food records (WFRs). Pearson and Spearman correlations, Bland–Altman plots and weighted kappa values were calculated.

Results

Compared with the WFR, the FFQ provided higher mean estimates of all nutrients except starch and GI. All Pearson and/or Spearman correlations were greater than 0.5, except for GL. For GI, sugar, starch and fibre, the regression lines from the Bland–Altman analysis indicated a non-significant linear trend (P= 0.07,P= 0.36,P= 0.28 andP= 0.10, respectively). For GL and total carbohydrate, however, there was a significant linear trend (P= 0.006 andP< 0.0001, respectively), indicating that as the GL and carbohydrate intake of individuals increased, so did the magnitude of the error between the FFQ and WFR. Weighted kappa values all indicated moderate to good agreement, with the exception of GL which was only fair. The proportions of subjects correctly classified within one quintile for all of the nutrients were over 50% and gross misclassification was low (<10%).

Conclusion

This FFQ was able to rank individuals according to their intakes of total carbohydrate, sugar, starch, fibre and GI, but not as well for GL.
Colonisation, the New World Order, and the eradication of traditional food habits in East Africa: historical perspective on the nutrition transition
Authors: Raschke Verena , Cheema Bobby
Published: October 2007

Objective

To discuss factors which have underpinned the nutrition transition in the countries of East Africa, including Kenya, Uganda and Tanzania, from early colonisation to the current, oppressive political–economic structure.

Results

Colonisation and neocolonisation in accordance with the desires of the New World Order have ensured the systematic extirpation of indigenous and traditional food habits in East Africa. These indigenous and traditional food habits, associated with myriad health benefits, have been progressively replaced by the globalised food system of the multinational corporations, a system inherently associated with the creation of non-communicable disease (NCD) epidemics throughout this region and globally. While the simplification of the East African food culture may be most apparent today, the nutrition transition has actually occurred over the past 400 years, since the onset of colonial occupation.

Conclusions

It is imperative that greater efforts be directed towards exposing the colonial and neocolonial forces which have undermined food security and health status in East Africa. Heightened awareness of these forces is essential for proposing genuine solutions to the nutrition transition and related NCD epidemics throughout this region and, indeed, worldwide.
Calcium Bioavailability from a New Calcium-Fortified Orange Beverage, Compared with Milk, in Healthy Volunteers
Authors: Gonnelli  , Campagna  , Montagnani  , Caffarelli  , Cadirni  , Giorgi  , Nuti
Published: October 2007

The recommended dietary calcium intake may be difficult to reach using dairy products only. This study aimed to evaluate the absorbability of calcium of a new orange beverage in comparison with that of milk. Ten healthy adults, 5 males and 5 females, were randomly divided to receive, under fasting conditions, an orange beverage enriched either with calcium or milk. Both the beverages had been labelled the previous evening with a ;44Ca solution. After a two-month interval the subjects underwent a crossover of beverages. Total and ionized calcium, parathyroid (PTH) hormone, and ;44Ca were evaluated. The ;44Ca was measured by inductively coupled plasma spectrometry. The relative changes in calcium absorption from the two test drinks were similar (23.0 ± 6.4% for milk and 20.9 ± 9.1% for the orange beverage). No significant differences were found between the two test groups. Both milk and orange beverage determined a similar and significant (p < 0.001) decrease in serum PTH two hours after the beginning of the test (–22.1 ± 14.0% for milk and –27.9 ± 15.3% for orange beverage). We can conclude that the bioavailability of calcium from this new calcium-enriched orange beverage is similar to that of milk.
Effect of Nicotinamide Administration on the Tryptophan-Nicotinamide Pathway in Humans
Authors: Fukuwatari  , Shibata
Published: October 2007

The vitamin nicotinamide is synthesized in the liver from tryptophan, and distributed to non-hepatic tissues. Although it is generally accepted that 60 mg tryptophan is equivalent to 1 mg nicotinamide in humans, the conversion ratio of tryptophan to nicotinamide is changeable. To determine if de novo nicotinamide synthesis from tryptophan is influenced by nicotinamide intake itself, six young women consumed controlled diets containing 30.4 or 24.8 mg niacin-equivalent nicotinamide supplements with 0, 89, 310, or 562 μmol/day (0, 10.9, 37.8, or 68.6 mg/day, respectively), and urinary excretion of intermediates and metabolites of the tryptophan-nicotinamide pathway were measured. Urinary excretion of nicotinamide metabolites increased linearly in a dose-dependent manner. None of the intermediates, including anthranilic acid, kynurenic acid, xanthurenic acid, 3-hydroxyanthranilic acid, and quinolinic acid, changed at all, even when up to 562 μmol/day nicotinamide was given. That is, exogenous nicotinamide did not affect de novo nicotinamide synthesis. Therefore, when niacin equivalent is calculated, the intake of nicotinamide itself need not be considered as a factor that changes the tryptophan-nicotinamide conversion ratio.
Vitamin E and Vitamin C Supplementation in Patients with Chronic Obstructive Pulmonary Disease
Authors: Wu  , Huang  , Hsu  , Wang  , Yeh
Published: October 2007

The purpose of this study was to determine whether vitamin E or vitamin C supplementation alters the DNA damage of whole blood white blood cells (WBC) in patients with chronic obstructive pulmonary disease (COPD). Thirty-five patients with stable COPD were recruited in this randomized and placebo-controlled study. Patients were randomly assigned to placebo (n = 8), 400 mg/day vitamin E (E400, n = 9), 200 mg/day vitamin E (E200, n = 9), or 250 mg/day vitamin C (C250, n = 9) for 12 weeks. The results showed that vitamin E or C supplementation did not significantly change the mean level of endogenous DNA breakages. Whereas, after 12 weeks of vitamin supplementation, the H2O2-induced DNA breakages were significantly suppressed by 45%, 59%, and 52%, respectively, in E400, E250 and C250 groups (p < 0.05). In addition, neither the level of thiobarbituric acid-reactive substances (TBARS) nor spirometric parameters were significantly changed after 12 weeks of supplementation. In conclusion, vitamin E or C supplementation for 12 weeks may improve the resistance of DNA in whole blood WBC against oxidative challenge, although more research is needed to demonstrate the beneficial effect on slowing the decline of lung function in patients with COPD.
Combined Effects of Swim Training and Ginseng Supplementation on Exercise Performance Time, ROS, Lymphocyte Proliferation, and DNA Damage Following Exhaustive Exercise Stress
Authors: Hwang  , Kwak  , Yoon  , Kang  , Park  , Lee  , Kim  , Um  , Kim
Published: October 2007

The purpose of this study was to analyze the combined effects of regular exercise and ginseng supplementation on peritoneal exudate ROS (reactive oxygen species), lymphocyte proliferation by splenocytes, and DNA damage following exhaustive exercise stress. Thirty-six female BALB/c mice were randomly divided into control (UT, n = 12), trained (TR, n = 12), and ginseng supplemented and trained (GT, n = 12) groups. Each group was divided into two equal subgroups where mice were studied at rest (UTre, TRre, and GTre) or immediately after exhaustive exercise stress (UTex, TRex, and GTex). Animals were bred in the animal facility, where they were housed at 22–24°C and relative humidity (RH) 50–60% in a controlled environment with a 12-hour photoperiod, and provided food and water ad libitum. The trained mice underwent 10 weeks of endurance swim training (5 times/week) in water at 27–30°C for 60 minutes. The analytical items examined were weight, proliferative activity, the production of ROS from peritoneal exudate cells, and DNA damage following exhaustive exercise stress (2 h exercise stress). Significant level was set at p < 0.05. The results obtained showed that the trained group had a significantly lower mean body weight than the untrained group (p < 0.05). However, there was no significant difference between UT and GT. Swim training increased swim survival time in TRex and GTex, and TRex showed the highest swim survival time. With regard to mitogenic activities of splenocytes in response to exhaustive exercise stress, all groups showed much lower lymphocyte proliferative activity when stimulated with media (Med), concanavalin A (ConA), or lipopolysaccharide (LPS) after exhaustive exercise stress. However, GTex had a higher proliferative activity than the other groups. Trained and ginseng-supplemented groups showed lower peritoneal ROS responses and lymphocyte DNA damage levels after exhaustive exercise. These findings suggest that the combined effect of swim training and ginseng supplementation sustain lymphocyte function in the presence of reduced ROS production and DNA damage following acute exercise stress.
Fortification of Eggs with Folic Acid as a Possible Contribution to Enhance the Folic Acid Status of Populations
Authors: Roth-Maier  , Böhmer
Published: October 2007

The aim of the present study was to evaluate the enrichment of folic acid in eggs by supplementing hens’ diet. Seventy-two hens (LSL) were assigned to 5 dietary groups and supplemented with 0, 0.5, 1.0, 2.0, and 4.0 mg folic acid/ kg feed during an 8-week period. Eggs for folic acid analysis were collected in weeks 4 and 8 and analyzed by microbiological method using L. casei. The performance of the hens was not influenced by the supplementation. The content of folic acid in eggs increased significantly from 3.1 μg/g DM to 5.5 μ g/g DM (week 4) and from 2.1 μ g/g DM to 4.2 μ g/g DM (week 8), respectively. One fortified egg can provide up to 76 μ g folic acid. Additionally the intestinal availability of folic acid in eggs was determined in pigs as an animal model for human nutrition. Six pigs were fitted with ileorectal-anastomosis and received boiled eggs combined with a supplementary diet according to nutrient requirement. The metabolic trial ran for 12 days with a pre-period of 7 days and a collection period of 5 days. Feed and chyme were analyzed for folic acid as mentioned above. The availability of folate in eggs was determined as 68%, which means that one fortified egg provides up to 52 μ g folate equivalent to 13% of the recommended daily intake.
Seismically and geodetically determined nondouble‐couple source mechanisms from the 2000 Miyakejima volcanic earthquake swarm
Authors: Minson Sarah E. , Dreger Douglas S. , Bürgmann Roland , Kanamori Hiroo , Larson Kristine M.
Published: October 2007

The volcanic eruption on Miyakejima, Japan, in 2000 was marked by the largest earthquake swarm ever recorded in Japan, a seismicity migration accompanying a dike intrusion as the dike propagated from Miyakejima to the northwest, and formation of a caldera on Mount Oyama on Miyakejima. In this study, we propose a seismic source model which can be used to model both seismic and geodetic displacements from volcanic earthquakes. Our model, the “crack + double‐couple” (CDC) model, combines tensile opening with shear slip along a single fault plane. We find that this model can fit both seismic and GPS data from the 1 July and 30 July earthquakes, the largest two in the Miyakejima sequence. The results of our GPS inversions for these two earthquakes are consistent with the seismic mechanisms and aftershock locations, and the GPS mechanisms successfully forward predict the observed regional seismograms. The 1 July earthquake, located near the northwest tip of the dike, has a large opening component and a geodetic moment about 5 times larger than that inferred from the seismic data alone. The source process for this event consists of tensile failure, which occurred quickly, and a much slower accumulation of shear slip. We apply the CDC model to 16 additional earthquakes from this sequence and find that the CDC model fits the seismic data for these earthquakes at least as well as established seismic moment tensor models.
Vertical distribution and optical properties of aerosols observed over Japan during the Atmospheric Brown Clouds–East Asia Regional Experiment 2005
Authors: Hayasaka Tadahiro , Satake Shinsuke , Shimizu Atsushi , Sugimoto Nobuo , Matsui Ichiro , Aoki Kazuma , Muraji Yoshitaka
Published: October 2007

Lidar and sky radiometer systems at Sapporo, Toyama, and Nagasaki, Japan, observed the vertical distributions and optical properties of (nonspherical) dust and spherical aerosol particles from March to May 2005 as part of the Atmospheric Brown Clouds–East Asia Regional Experiment 2005 (ABC‐EAREX2005). Sky radiometer observations suggest that single scattering albedo at Nagasaki was smaller than that at Toyama and Sapporo. Relationships between the single scattering albedo and Ångstrom exponent suggest that aerosol particles observed at Toyama in March differed from those observed in April and May. In contrast, at Nagasaki, there was no obvious difference in aerosol particles among the 3 months. Aerosol optical thicknesses observed by the sky radiometer resemble the aerosol optical thicknesses observed by lidar and simulated by the Chemical Weather Forecasting System (CFORS) model. A new parameter that describes the aerosol vertical distribution, Hm, is the modified scale height of the extinction coefficient. Hm can be used as an index of the vertical aerosol extent even if the detailed structure of the vertical profile cannot be shown. Hm observed by lidar was consistent with Hm simulated by the CFORS. Relationships between the aerosol optical thickness and Hm obtained by lidar measurements and CFORS simulations suggest that dust aerosol particles are generally transported over Japan at higher altitudes than are spherical aerosol particles.
Energy exchange rate for the equatorial electrojet: Test of the model of two‐stream processes that includes thermal corrections
Authors: Kagan L. M. , Kissack R. S.
Published: October 2007

The experiment of Balsley and Farley (1971) in Jicamarca, Peru has been the only multi(3)‐frequency investigation of the equatorial electrojet. The radar was operated sequentially at frequencies of 16.25, 49.92 and 146.25 MHz and probed the same ionospheric volume. The most prominent feature of these observations was the increase in the phase velocity Vph of Farley‐Buneman (FB) waves with increasing radar frequency while the classical fluid theory gives Vph independent on their wavelength and the simple kinetic theory accounts for only a small increase in Vph. Our recent theory predicts a wavenumber dependence of the FB wave phase velocity. The rate of increase depends on the altitude of the electrojet and seems to match the observed wave behavior. The most important byproduct of this case study is our conclusion that the energy exchange rate in inelastic electron‐neutral interactions is about two‐to‐three times higher that it has been assumed in estimates.
Rupture characterization and aftershock relocations for the 1994 and 2006 tsunami earthquakes in the Java subduction zone
Authors: Bilek Susan L. , Engdahl E. Robert
Published: October 2007

Two tsunami earthquakes occurred in the Java subduction zone within the last 12 years, providing multiple well‐recorded tsunami events for analysis. The June 2, 1994 Mw = 7.8 and July 17, 2006 Mw = 7.7 reverse mechanism earthquakes produced tsunami with locally large (>8 m) runups, were deficient in high frequency energy relative to long period radiation, had primarily normal faulting aftershocks, and occurred near subducting seamounts. Previous models of the 1994 event and aftershocks suggested extension in the outer rise due to slip at depth at a subducted seamount. Here we relocate aftershocks for the 1994 and 2006 events and compare to slip distributions and bathymetry. Most 1994 aftershocks occurred within the slab updip of the mainshock, consistent with the extensional hypothesis, but the 2006 aftershocks have a more complex pattern. Regional subducting features as asperities and barriers may influence both events, but in different ways.
Equatorial spread F‐related airglow depletions at Arecibo and conjugate observations
Authors: Martinis C. , Mendillo M.
Published: October 2007

We present evidence of the incursion into the Caribbean region of airglow depletions associated with the equatorial Rayleigh‐Taylor instability. Data from the Boston University all‐sky imager located at Arecibo, Puerto Rico (18.3°N, 66.7°W, 28°N magnetic latitude), have been used to identify several nights with 630.0 nm airglow patterns that are typical signatures of equatorial spread F and distinctly different from the more common “airglow bands” frequently observed there. Two case studies (2 November 2002 and 26 February 2003) show the occurrence of simultaneous airglow depletions observed with another all‐sky imager located at El Leoncito, Argentina (31.8°S, 69.3°W, 18°S magnetic latitude), relatively close to the Arecibo conjugate point. Supporting information is obtained from Defense Meteorological Satellite Program, ROCSAT‐1, and GPS data, all of them showing the presence of strong ionospheric irregularities collocated with the airglow depletions. Mapping the circular field of view from Arecibo into the Southern Hemisphere reveals a distorted pattern due to the differences in the magnetic field characteristics in both hemispheres. This adds an interesting spatial complexity to the formulation of conjugate point observing programs in the Latin American longitude sector.
A Simple, Rapid Method for Extracting Large Plasmid DNA from Bacteria
Authors: Heringa Spencer , Monroe Jonathan , Herrick James
Published: October 2007

We are studying the lateral transfer of transmissible antibiotic resistance plasmids among stream bacteria impacted by fecal runoff from poultry and cattle. Such plasmids are typically large (ca. 40 – 100 kb) and occur in low copy numbers in the cell and have therefore typically been difficult to isolate and therefore to study. Traditional protocols, based upon variations of the standard alkaline-lysis method, are long (ca. 1 1/2 to 2 days) and difficult. Commercial kits designed for the isolation of Baterial Artificial Chromosomes (BACs) can be used and are an improvement; however, these are expensive and still require hours of sustained effort. We have adapted a method published by Rondon et al. (1999), originally designed for the isolation of BAC DNA, for the rapid isolation of large plasmid DNA. In this method, lysis and alkaline denaturation steps are combined, incubation steps are vastly reduced, proteins are removed via a simple ammonium acetate/chloroform step, and the DNA precipitated using a plyethylene glycol/NaCl step. No ethanol precipitation is required. If additional purification is required, extracted DNA can be further processed through a Qiagen Plasmid Mini or Midi column (Qiagen Inc., Valencia CA). The method is rapid (under 1 hour), easy, very inexpensive and has been reliably used by undergraduate students to isolate large (up to 200 kb) native plasmids from a variety of both Gram-positive and Gram-negative genera including Shigella, Klebsiella, E. coli, Pseudomonas, Bacills, Streptococcus, Staphylococcus, and Enterococcus, as well as BACs from E. coli. The protocol is simple and reliable enough to be used for the rapid large-scale visualization of native plasmids and we have used it to visualize and isolate DNA from hundreds of multidrug resistance plasmids exogenously captured from stream sediments, soils, and beach sands.
Multivariate and Univariate Analysis of Continuous Arterial Spin Labeling Perfusion MRI in Alzheimer's Disease
Authors: Asllani Iris , Habeck Christian , Scarmeas Nikolaos , Borogovac Ajna , Brown Truman R , Stern Yaakov
Published: October 2007

Continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI) was combined with multivariate analysis for detection of an Alzheimer's disease (AD)-related cerebral blood flow (CBF) covariance pattern. Whole-brain resting CBF maps were obtained using spin echo, echo planar imaging (SE-EPI) CASL in patients with mild AD ( n=12, age=70.7±8.7 years, 7 males, modified Mini-Mental State Examination (mMMS)=38.7/57±11.1) and age-matched healthy controls (HC) ( n=20; age=72.1±6.5 years, 8 males). A covariance pattern for which the mean expression was significantly higher ( P<0.0005) in AD than in HC was identified containing posterior cingulate, superior temporal, parahippocampal, and fusiform gyri, as well as thalamus, insula, and hippocampus. The results from this analysis were supplemented with those from the more standard, region of interest (ROI) and voxelwise, univariate techniques. All ROIs (17/hemisphere) showed significant decrease in CBF in AD ( P<0.001 for all ROIs, αcorrected=0.05). The area under the ROC curve for discriminating AD versus HC was 0.97 and 0.94 for covariance pattern and gray matter ROI, respectively. Fewer areas of depressed CBF in AD were detected using voxelwise analysis (corrected, P<0.05). These areas were superior temporal, cingulate, middle temporal, fusiform gyri, as well as inferior parietal lobule and precuneus. When tested on extensive split-half analysis to map out the replicability of both multivariate and univariate approaches, the expression of the pattern from multivariate analysis was superior to that of the univariate.
Hg
+
Br
→
Hg
Br
recombination and collision-induced dissociation dynamics
Authors: Shepler Benjamin C. , Balabanov Nikolai B. , Peterson Kirk A.
Published: October 2007

A global potential energy surface has been constructed for the system HgBr+Ar→Hg+Br+Ar to determine temperature dependent rate constants for the collision-induced dissociation (CID) and recombination of Hg and Br atoms. The surface was decomposed using a many-body expansion. Accurate two-body potentials for HgBr, HgAr, and ArBr were calculated using coupled cluster theory with single and double excitations and a perturbative treatment of triple excitations [CCSD(T)], as well as the multireference averaged coupled pair functional method. Correlation consistent basis sets were used to extrapolate to the complete basis set limit and corrections were included to account for scalar and spin-orbit relativistic effects, core-valence correlation, and the Lamb shift. The three-body potential was computed with the CCSD(T) method and triple-zeta quality basis sets. Quasiclassical trajectories using the final analytical potential surface were directly carried out on the CID of HgBr by Ar for a large sampling of initial rotational, vibrational, and collision energies. The recombination rate of Hg and Br atoms is a likely first step in mercury depletion events that have been observed in the Arctic troposphere during polar sunrise. The effective second order rate constant for this process was determined in this work from the calculated CID rate as a function of temperature using the principle of detailed balance, which resulted in k(T)=1.2×10−12cm3molecule−1s−1 at 260K and 1bar pressure.
Rotationally resolved spectroscopy of jet-cooled NbMo
Authors: Nagarajan Ramya , Morse Michael D.
Published: October 2007

Rotationally resolved resonant two-photon ionization spectra of jet-cooled NbMo are reported for the first time. A vibronic spectrum of NbMo was recorded in the 17300–22300cm−1 spectral region. Although the observed bands could not be grouped into electronic band systems, four excited vibronic levels with Ω=2.5 and two excited levels with Ω=3.5 were identified. The ground state of NbMo has been assigned as Δ5∕22, deriving from a 1σ21π41δ32σ2 configuration of the valence electrons. Rotational analysis of six bands provides a ground state rotational constant of B0″=0.087697(26)cm−1, corresponding to a bond length of r0″=2.00809(30)Å for Nb93Mo98. Correction for the effects of the spin-uncoupling operator changes the estimated bond length only slightly to r0″=2.00802(30)Å. The experimentally determined value of r0″ is compared to that predicted using previously determined multiple bonding radii of Nb and Mo. A comparison to the known diatomic molecules composed of group V and VI metal atoms is also made.
Effects of sharp vorticity gradients in two-dimensional hydrodynamic turbulence
Authors: Kuznetsov E. A. , Naulin V. , Nielsen A. H. , Rasmussen J. Juul
Published: October 2007

The appearance of sharp vorticity gradients in two-dimensional hydrodynamic turbulence and their influence on the turbulent spectra are considered. We have developed the analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the divorticity lines. Compressibility of this mapping can be considered as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. For two-dimensional turbulence in the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k−3 at large k, resembling the Kraichnan spectrum for the enstrophy cascade. For turbulence with weak anisotropy the k dependence of the spectrum due to the sharp gradients coincides with the Saffman spectrum, E(k)∼k−4. We have compared the analytical predictions with direct numerical solutions of the two-dimensional Euler equation for decaying turbulence. We observe that the divorticity is reaching very high values and is distributed locally in space along piecewise straight lines, thus indicating strong anisotropy, and accordingly we find a spectrum close to the k−3 spectrum.
Localized wake-field excitation and relativistic wave-breaking
Authors: Lehmann G. , Laedke E. W. , Spatschek K. H.
Published: October 2007

The localized wake-field behavior behind a short laser pulse is analyzed numerically as well as analytically in one space dimension. A laser pulse propagating in an underdense plasma oscillates in amplitude and width. Within a certain parameter regime, the variations may be near the threshold for wake-field generation. During the times when the width becomes small enough, localized electrostatic wave-packets are generated. The latter may have amplitudes in the relativistic regime. The breaking of the wake-field wave packets is investigated. Known criteria for wave-breaking are generalized to the relativistic and inhomogeneous cases. It is found that relativistic, inhomogeneous packets break without threshold; however, not, in general, on the first oscillation. The time for wave-breaking can be estimated. The numerical findings are proven analytically by making use of a Lagrangian coordinate formulation.
The effect of Ga vacancies on the defect and magnetic properties of Mn-doped GaN
Authors: Kang Joongoo , Chang K. J.
Published: October 2007

We perform first-principles theoretical calculations to investigate the effect of the presence of Ga vacancy on the defect and magnetic properties of Mn-doped GaN. When a Ga vacancy (VGa) is introduced to the Mn ions occupying the Ga lattice sites, a charge transfer occurs from the Mn d band to the acceptor levels of VGa, and strong Mn–N bonds are formed between the Mn ion and the N atoms in the neighborhood of VGa. The charge transfer and chemical bonding effects significantly affect the defect and magnetic properties of Mn-doped GaN. In a Mn-VGa complex, which consists of a Ga vacancy and one Mn ion, the dangling bond orbital of the N atom involved in the Mn–N bond is electrically deactivated, and the remaining dangling bond orbitals of VGa lead to the shallowness of the defect level. When a Ga vacancy forms a complex with two Mn ions located at a distance of about 6 Å, which corresponds to the percolation length in determining the Curie temperature in diluted Mn-doped GaN, the Mn d band is broadened and the density of states at the Fermi level is reduced due to two strong Mn–N bonds. Although the broadening and depopulation of the Mn d band weaken the ferromagnetic stability between the Mn ions, the ferromagnetism is still maintained because of the lack of antiferromagnetic superexchange interactions at the percolation length.
Polysilane based organic light emitting diodes: Simultaneous ultraviolet and visible emission
Authors: Sharma Asha , Katiyar Monica , Deepak  , Seki Shu
Published: October 2007

While most organic light emitting diodes are designed to emit in the visible region, we report a series of polysilane based diodes for developing ultraviolet emitters at room temperature. These reported devices can also be controlled to simultaneously emit both ultraviolet and visible light, very close to the equienergy white point [Commission Internationale de l’Eclairage coordinate (0.33,0.33)]. Furthermore, the color coordinate of the visible emission is independent of the applied voltage. Therefore, the reported polysilane organic light emitting diodes can also be used as a white light source in which the ultraviolet emission from the same device provides an opportunity to modulate the color. While the origin of ultraviolet emission in electroluminescence is ascribed to an excitonic emission from the σ-σ* transition, consistent with its presence in the photoluminescence spectrum, we assign visible emission to defects states, based on degradation studies of the electroluminescent device.
Mechanisms for enhanced supercurrent across meandered grain boundaries in high-temperature superconductors
Authors: Feldmann D. M. , Holesinger T. G. , Feenstra R. , Cantoni C. , Zhang W. , Rupich M. , Li X. , Durrell J. H. , Gurevich A. , Larbalestier D. C.
Published: October 2007

It has been well established that the critical current density Jc across grain boundaries (GBs) in high-temperature superconductors decreases exponentially with misorientation angle θ beyond ∼2°–3°. This rapid decrease is due to a suppression of the superconducting order parameter at the grain boundary, giving rise to weakly pinned Abrikosov-Josephson (AJ) vortices. Here we show that if the GB plane meanders, this exponential dependence no longer holds, permitting greatly enhanced Jc values: up to six times at 0T and four times at 1T at θ∼4°–6°. This enhancement is due to an increase in the current-carrying cross section of the GBs and the appearance of short AJ vortex segments in the GB plane, confined by the interaction with strongly pinned Abrikosov (A) vortices in the grains.
The role of surface vibrations and quantum confinement effect to the optical properties of very thin nanocrystalline silicon films
Authors: Lioudakis Emmanouil , Antoniou Antreas , Othonos Andreas , Christofides Constantinos , Nassiopoulou A. G. , Lioutas Ch. B. , Frangis N.
Published: October 2007

We report on a spectroscopic study of very thin nanocrystalline silicon films varying between 5 and 30nm. The role of quantum confinement effect and surface passivation of nanograins in optical properties are examined in detail. The coupling between surface vibrations and fundamental gap Eg as well as the increase of interaction between them at the strong confinement regime (⩽2nm) are proposed for the observable pinning of Eg in luminescence measurements.
Two-dimensional inviscid pinch-off: An example of self-similarity of the second kind
Authors: Burton J. C. , Taborek P.
Published: October 2007

The pinch-off of a two-dimensional region of inviscid fluid is investigated using numerical and analytical techniques. We find that pinch-off occurs when a sufficiently deformed 2D drop is released from rest. The asymptotic collapse of the pinching region is characterized by an anomalous, nonrational similarity exponent α, indicating the existence of self-similarity of the second kind. Numerical solutions of the boundary integral equations show that the height of the pinch region shrinks faster than the width, so that the singularity can be described by a slender approximation. The partial differential equations obtained from this approximation are solved and are consistent with the full boundary integral methods. Furthermore, by casting the partial differential equations into similarity form, we solve a nonlinear eigenvalue problem to obtain the value of the similarity exponent, α=0.6869±0.0003.
High-frequency characterization and modeling of paraelectric∕superconductor resonators for high power-handling microwave passive devices
Authors: Seron D. , Guyard S. , Bouzehouane K. , Lemaitre Y. , Marcilhac B. , Mage J. C.
Published: October 2007

The theoretical conditions required to observe reduced nonlinearities in passive microwave devices made of a paraelectric (PE) thin layer and a high-temperature superconductor (HTS) thin film are presented. In a transmission line (TL) combining both materials, the nonlinear permittivity εr(Vrf) of the PE generates a nonlinear capacitive contribution Cd(Vrf), whereas the nonlinear penetration depth λ(Irf) of the HTS produces a nonlinear inductive contribution Ld(Irf). These contributions act in opposite ways. Under determined conditions that will be defined, they may fully compensate or at least lead to the reduction of the spurious signal level. The HTS nonlinearities may be lowered by employing very thin layers of PE. In this case, the high dielectric loss tangent (tanδ) of PE should not be such an issue. Based on experimental results obtained with superconducting YBa2Cu3O7−δ resonators integrating different thicknesses of paraelectric SrTiO3 (STO) deposited on LaAlO3 substrates, the loss level could then be considered in the simulation of the proposed compensation effect. The results show that the reduction of the unloaded quality factor (Q0) as the thickness of STO increases also impacts the level of spurious signals. Then, an analytic expression for the Q0 of a resonant TL that integrates a PE and a HTS thin layer is proposed. It specifies the conditions for reducing the total nonlinear response. These results could then be applied to realize high power handling HTS passive microwave devices.
Scenario of electropoling on the molecular scale within a stoichiometric lithium niobate
Authors: Liao Chungpin , Chang Hsien-Ming , Yang Bin-Huang
Published: October 2007

Macroscopic formation scenario of periodically poled lithium niobates (PPLNs) had been evidenced through various in situ optical means, though with their molecular details remaining unclear. The traditional charge pumping model does not naturally correlate to the observed coercive field or to the molecular-level physics. Here, numerical efforts based on the first-principles quantum mechanics were launched from the energetic perspective and morphologies of energy barriers on the molecular scale were exposed. It appeared that to achieve a stoichiometric PPLN at observed low coercive field strength of 200V∕mm, the expanding inversion front ought to possess a domain wall width of the order of 20 primitive cells (or on the order of 10nm).
Coexistence of tetrahedral- and octahedral-like sites in amorphous phase change materials
Authors: Caravati S. , Bernasconi M. , Kühne T. D. , Krack M. , Parrinello M.
Published: October 2007

Chalcogenide alloys are materials of interest for optical recording and nonvolatile memories. We perform ab initio molecular dynamics simulations aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the prototypical material in this class. First principles simulations show that amorphous GST obtained by quenching from the liquid phase displays two types of short range order. One third of Ge atoms are in a tetrahedral environment while the remaining Ge, Sb, and Te atoms display a defective octahedral environment, reminiscent of cubic crystalline GST.
Organic mixed-order photonic crystal lasers with ultrasmall footprint
Authors: Baumann Kristian , Stöferle Thilo , Moll Nikolaj , Mahrt Rainer F. , Wahlbrink Thorsten , Bolten Jens , Mollenhauer Thomas , Moormann Christian , Scherf Ulli
Published: October 2007

The lasing properties of an optimized two-dimensional photonic crystal structure with an organic gain material are investigated. The feedback structure which is fabricated in a thin film of Ta2O5 increases both the index contrast from the gain material as well as the optical confinement. By combining first-order and second-order photonic crystal structures, losses occuring at the edge of the second order structure are dramatically reduced leading to a lower laser threshold and/or to a much smaller footprint of the laser.
Effects of the oxygen precursor on the interface between (100)Si and HfO2 films grown by atomic layer deposition
Authors: Baldovino S. , Spiga S. , Scarel G. , Fanciulli M.
Published: October 2007

The interface between (100)Si and HfO2 grown by atomic layer deposition is strongly influenced by the choice of the oxygen precursor. In particular, the use of oxidants with different oxidizing power such as H2O and O3 produces interfaces differing both in terms of density of electronic traps and defect microstructure. While H2O produces a Si∕SiO2-like interface, characterized by the presence of the Pb0 center, the high reactivity of O3 induces a modification in the defect wavefunction, as revealed by electrically detected magnetic resonance. Post growth annealing in N2 at T⩾600°C allows the recovery of a Si∕SiO2-like interface.
Observation of metallic indium clusters in thick InGaN layer grown by metal organic chemical vapor deposition
Authors: Zhu X. L. , Guo L. W. , Ge B. H. , Peng M. Z. , Yu N. S. , Yan J. F. , Zhang J. , Jia H. Q. , Chen H. , Zhou J. M.
Published: October 2007

Pure metallic indium clusters of 10–50nm are identified in In0.37Ga0.63N film grown by metal organic chemical vapor deposition based on analysis of x-ray diffraction, transmission electron microscopy, selected area diffraction, and high resolution transmission electron microscopy (HRTEM). The in-plane orientation relationships are InGaN[11−20]‖metallic indium [0−10], InGaN [1−100]‖metallic indium [−101], and InGaN [0001]‖metallic indium [101] along the growth direction. The rocking curve of indium (101) diffraction shows a large full width at half maximum of 3060arcsec, which is consistent with the small size of the indium clusters observed in HRTEM.
Stellar Models and Yields of Asymptotic Giant Branch Stars
Authors: Karakas Amanda , Lattanzio John C.
Published: October 2007

We present stellar yields calculated from detailed models of low and intermediate-mass asymptotic giant branch (AGB) stars. We evolve models with a range of mass from 1 to 6 M⊙, and initial metallicities from solar to 1/200th of the solar metallicity. Each model was evolved from the zero age main sequence to near the end of the thermally pulsing (TP) AGB phase, and through all intermediate phases including the core He-flash for stars initially less massive than 2.5 M⊙. For each mass and metallicity, we provide tables containing structural details of the stellar models during the TP-AGB phase, and tables of the stellar yields for 74 species from hydrogen through to sulfur, and for a small number of iron-group nuclei. All tables are available for download. Our results have many applications including use in population synthesis studies and the chemical evolution of galaxies and stellar systems, and for comparison to the composition of AGB and post-AGB stars and planetary nebulae.
SPLASH: An Interactive Visualisation Tool for Smoothed Particle Hydrodynamics Simulations
Authors: Price Daniel J.
Published: October 2007

This paper presents SPLASH, a publicly available interactive visualisation tool for Smoothed Particle Hydrodynamics (SPH) simulations. Visualisation of SPH data is more complicated than for grid-based codes because the data are defined on a set of irregular points and therefore requires a mapping procedure to a two dimensional pixel array. This means that, in practise, many authors simply produce particle plots which offer a rather crude representation of the simulation output. Here we describe the techniques and algorithms which are utilised in SPLASH in order to provide the user with a fast, interactive and meaningful visualisation of one, two and three dimensional SPH results.
Attenuation of store-operated Ca
2+
current impairs salivary gland fluid secretion in TRPC1(−/−) mice
Authors: Liu Xibao , Cheng Kwong Tai , Bandyopadhyay Bidhan C. , Pani Biswaranjan , Dietrich Alexander , Paria Biman C. , Swaim William D. , Beech David , Yildrim Eda , Singh Brij B. , Birnbaumer Lutz , Ambudkar Indu S.
Published: October 2007

Agonist-induced Ca
2+
entry via store-operated Ca
2+
(SOC) channels is suggested to regulate a wide variety of cellular functions, including salivary gland fluid secretion. However, the molecular components of these channels and their physiological function(s) are largely unknown. Here we report that attenuation of SOC current underlies salivary gland dysfunction in mice lacking transient receptor potential 1 (TRPC1). Neurotransmitter-regulated salivary gland fluid secretion in TRPC1-deficient TRPC1(−/−) mice was severely decreased (by 70%). Further, agonist- and thapsigargin-stimulated SOC channel activity was significantly reduced in salivary gland acinar cells isolated from TRPC1(−/−) mice. Deletion of TRPC1 also eliminated sustained Ca
2+
-dependent potassium channel activity, which depends on Ca
2+
entry and is required for fluid secretion. Expression of key proteins involved in fluid secretion and Ca
2+
signaling, including STIM1 and other TRPC channels, was not altered. Together, these data demonstrate that reduced SOC entry accounts for the severe loss of salivary gland fluid secretion in TRPC1(−/−) mice. Thus, TRPC1 is a critical component of the SOC channel in salivary gland acinar cells and is essential for neurotransmitter-regulation of fluid secretion.
Defined DNA sequences promote the assembly of a bacterial protein into distinct amyloid nanostructures
Authors: Giraldo Rafael
Published: October 2007

RepA, the replication initiator protein of
Pseudomonas
pPS10 plasmid, is made of two
winged-helix
(WH) domains. RepA dimers undergo a structural transformation upon binding to origin DNA sequences (iterons), resulting in monomerization and α-helix into β-strand conversion. This affects the N-terminal domain (WH1) and generates a metastable intermediate. Here it is shown that the interaction of short dsDNA oligonucleotides, including iteron or operator RepA targets, with the isolated WH1 domain promotes the assembly of different nanostructures. These range from irregular aggregates to amyloid spheroids and fibers. Their intrinsic order inversely correlates with the extent of the transformation induced by each DNA sequence on RepA. However, DNA is not a constituent of the assembled fibers, in agreement with the protein-only principle for amyloid structure. Thus, the RepA-WH1 domain on DNA binding mimics the behavior of the mammalian prion protein. The stretch of amino acids responsible for WH1 aggregation has been identified, leading to the design of mutants with enhanced or reduced amyloidogenicity and the synthesis of a peptide that assembles into a cross-β structure. RepA amyloid assemblies could have a role in the negative regulation of plasmid replication. This article underlines the potential of specific nucleic acid sequences in promoting protein amyloidogenesis at nearly physiological conditions.
Optimal approach to quantum communication using dynamic programming
Authors: Jiang Liang , Taylor Jacob M. , Khaneja Navin , Lukin Mikhail D.
Published: October 2007

Reliable preparation of entanglement between distant systems is an outstanding problem in quantum information science and quantum communication. In practice, this has to be accomplished by noisy channels (such as optical fibers) that generally result in exponential attenuation of quantum signals at large distances. A special class of quantum error correction protocols, quantum repeater protocols, can be used to overcome such losses. In this work, we introduce a method for systematically optimizing existing protocols and developing more efficient protocols. Our approach makes use of a dynamic programming-based searching algorithm, the complexity of which scales only polynomially with the communication distance, letting us efficiently determine near-optimal solutions. We find significant improvements in both the speed and the final-state fidelity for preparing long-distance entangled states.
Engineered bidirectional communication mediates a consensus in a microbial biofilm consortium
Authors: Brenner Katie , Karig David K. , Weiss Ron , Arnold Frances H.
Published: October 2007

Microbial consortia form when multiple species colocalize and communally generate a function that none is capable of alone. Consortia abound in nature, and their cooperative metabolic activities influence everything from biodiversity in the global food chain to human weight gain. Here, we present an engineered consortium in which the microbial members communicate with each other and exhibit a “consensus” gene expression response. Two colocalized populations of
Escherichia coli
converse bidirectionally by exchanging acyl-homoserine lactone signals. The consortium generates the gene-expression response if and only if both populations are present at sufficient cell densities. Because neither population can respond without the other's signal, this consensus function can be considered a logical AND gate in which the inputs are cell populations. The microbial consensus consortium operates in diverse growth modes, including in a biofilm, where it sustains its response for several days.
Blood group O protects against severe
Plasmodium falciparum
malaria through the mechanism of reduced rosetting
Authors: Rowe J. Alexandra , Handel Ian G. , Thera Mahamadou A. , Deans Anne-Marie , Lyke Kirsten E. , Koné Abdoulaye , Diallo Dapa A. , Raza Ahmed , Kai Oscar , Marsh Kevin , Plowe Christopher V. , Doumbo Ogobara K. , Moulds Joann M.
Published: October 2007

Malaria has been a major selective force on the human population, and several erythrocyte polymorphisms have evolved that confer resistance to severe malaria.
Plasmodium falciparum
rosetting, a parasite virulence phenotype associated with severe malaria, is reduced in blood group O erythrocytes compared with groups A, B, and AB, but the contribution of the ABO blood group system to protection against severe malaria has received little attention. We hypothesized that blood group O may confer resistance to severe falciparum malaria through the mechanism of reduced rosetting. In a matched case-control study of 567 Malian children, we found that group O was present in only 21% of severe malaria cases compared with 44–45% of uncomplicated malaria controls and healthy controls. Group O was associated with a 66% reduction in the odds of developing severe malaria compared with the non-O blood groups (odds ratio 0.34, 95% confidence interval 0.19–0.61,
P
< 0.0005, severe cases versus uncomplicated malaria controls). In the same sample set,
P. falciparum
rosetting was reduced in parasite isolates from group O children compared with isolates from the non-O blood groups (
P
= 0.003, Kruskal–Wallis test). Statistical analysis indicated a significant interaction between host ABO blood group and parasite rosette frequency that supports the hypothesis that the protective effect of group O operates through the mechanism of reduced
P. falciparum
rosetting. This work provides insights into malaria pathogenesis and suggests that the selective pressure imposed by malaria may contribute to the variable global distribution of ABO blood groups in the human population.