bluuebunny/crossref_metadata_2025 huggingface dataset:
Small changes in snacking behaviour: the potential impact on CVD mortality
Authors: Lloyd-Williams Ffion , Mwatsama Modi , Ireland Robin , Capewell Simon
Published: August 2008

Objective

To examine the potential public health impact on CHD and stroke mortality of replacing one ‘unhealthy’ snack with one ‘healthy’ snack per person, per day, across the UK population.

Methods

Nutritional information was obtained for different ‘unhealthy’ (such as crisps, chocolate bars, cakes and pastries) and ‘healthy’ snack products (such as fresh fruit, dried fruit, unsalted nuts or seeds). Expected changes in dietary intake were calculated. The mean change in total blood cholesterol levels was estimated using the Keys equation. The effect of changing cholesterol and salt levels on CHD deaths and on stroke deaths was calculated using the appropriate equations from the Law and He meta-analyses. The estimated reductions in cardiovascular deaths were then tested in a sensitivity analysis.

Results

Substituting one ‘healthy’ snack would reduce saturated fat intake by approximately 4·4 g per person per day, resulting in approximately 2400 fewer CHD deaths and 425 fewer stroke deaths per year. The associated 500 mg decrease in salt intake would result in approximately 1790 fewer CHD deaths and 1330 fewer stroke deaths.

Conclusions

Simply replacing one unhealthy snack with one healthy snack per day might prevent approximately 6000 cardiovascular deaths every year in the UK.
Effect of combining multiple micronutrients with iron supplementation on Hb response in children: systematic review of randomized controlled trials
Authors: Gera Tarun , Sachdev Harsh Pal Singh , Nestel Penelope
Published: August 2008

Objectives

To study the effect of combining multiple (two or more) micronutrients with Fe supplementation on Hb response, when compared with placebo and with Fe supplementation, in children.

Data sources

Electronic databases, personal files, hand search of reviews, bibliographies of books, and abstracts and proceedings of international conferences.

Review methods

Randomized controlled trials evaluating change in Hb levels with interventions that included Fe and multiple-micronutrient supplementation in comparison to placebo alone or Fe alone were analysed in two systematic reviews.

Results

Twenty-five trials were included in the review comparing Fe and micronutrient supplementation with placebo. The pooled estimate (random effects model) for change in Hb with Fe and micronutrient supplementation (weighted mean difference) was 0·65 g/dl (95 % CI 0·50, 0·80,P< 0·001). Lower baseline Hb, lower height-for-ageZscore, non-intake of ‘other micronutrients’ and malarial non-hyperendemic region were significant predictors of greater Hb response and heterogeneity. Thirteen trials were included in the review comparing Fe and micronutrient supplementation with Fe alone. The pooled estimate for change in Hb with Fe and micronutrient supplementation (weighted mean difference) was 0·14 g/dl (95 % CI 0·00, 0·28,P= 0·04). None of the variables were found to be significant predictors of Hb response.

Conclusions

Synthesized evidence indicates that addition of multiple micronutrients to Fe supplementation may only marginally improve Hb response compared with Fe supplementation alone. However, addition of ‘other micronutrients’ may have a negative effect. Routine addition of unselected multiple micronutrients to Fe therefore appears unjustified for nutritional anaemia control programmes.
Meals and snacks from the child’s perspective: the contribution of qualitative methods to the development of dietary interventions
Authors: Husby Ida , Heitmann Berit L , O’Doherty Jensen Katherine
Published: August 2008

Objective

To explore the everyday consumption of meals and snacks from the child’s perspective, among those with healthierv. less healthy dietary habits.

Design

The sample in this qualitative study comprised two groups of Danish schoolchildren aged 10 to 11 years, one with a healthier diet (n9) and the other with a less healthy diet (n8). Both groups were recruited from respondents to a dietary survey. Semi-structured interviews took their starting point in photographs of their meals and snacks taken by the children themselves.

Results

Both subgroups of children had a meal pattern with three main meals and two to four snacks. We found a connection between the nutritional quality of the diet and the social contexts of consumption, especially with regard to snacks. Among children with healthier eating habits, both snacks and meals tended to be shared social events and items of poor nutritional quality functioned as markers of a special social occasion. This was not the case among children with less healthy eating habits. All children described particular rules governing food consumption within their families. Although only some of them had participated in the development of these rules, and despite the fact that rules were different and were perceived as having been developed for different reasons, children from both subgroups tended to accept them.

Conclusions

The results of the study suggest that dietary interventions designed to promote children’s health should focus more on the different social contexts of consumption and more on the role of parents.
Modeling framework for sediment deposition, storage, and evacuation in the floodplain of a meandering river: Application to the Clark Fork River, Montana
Authors: Lauer J. Wesley , Parker Gary
Published: August 2008

A theory for the evolution of a river floodplain and the associated movement of tracer sediment is applied to the case of the upper Clark Fork River, Montana, whose floodplain is contaminated with tailings derived from historical mining activities. Deposition of mine tailings raised the elevation of the floodplain, which now contributes contaminated sediment to the channel. The theory is capable of reproducing the basic aspects of the system's evolution, including aggradation of the floodplain during the mining era and subsequent net supply of sediment from floodplain to channel after the cessation of mine input. Results indicate that the natural removal of tailings from the floodplain could take thousands of years, a period longer than is required for the channel to simply rework the tailings. The self‐stabilizing nature of the model results in an evolution toward a new postmine steady state, with tailings eventually almost entirely removed from the system.
Modeled natural and excess radiocarbon: Sensitivities to the gas exchange formulation and ocean transport strength
Authors: Müller S. A. , Joos F. , Plattner G.‐K. , Edwards N. R. , Stocker T. F.
Published: August 2008

Observation‐based surface ocean Δ14C distributions and regional inventories for excess, bomb‐produced radiocarbon are compared with results of two ocean models of intermediate complexity. By applying current descriptions of the air‐sea gas exchange the models produce similar column inventories for excess 14C among all basins. This result is robust across a wide range of transport parameter settings, but inconsistent with data‐based inventories. In the absence of evidence of fundamentally different gas exchange mechanisms in the North Atlantic than in the other basins, we infer regional North Atlantic 14C inventories which are considerably smaller than previous estimates. The results further suggest that the gas exchange velocity field should be reduced by (19 ± 16)%, which corresponds to a global mean air‐sea gas transfer rate for CO2 in seawater of 17.1 ± 3.3 cm h−1, to find good agreement of simulated quantities with a range of data‐based metrics.
On the importance of accurate solar wind measurements for studying magnetospheric dynamics
Authors: Ashour‐Abdalla Maha , Walker Raymond J. , Peroomian Vahe , El‐Alaoui Mostafa
Published: August 2008

We have examined the validity of assuming that the solar wind observed at the L1 Lagrange point is a good predictor of the environment at the Earth by using solar wind observations during a magnetic storm from four spacecraft (ACE, Wind, IMP‐8, and Geotail). The storm on 23 and 24 May 2000 occurred when a magnetic cloud reached the Earth. We carried out a running cross‐correlation analysis between the solar wind parameters observed on pairs of the solar wind spacecraft and found good agreement early in the storm. The peak cross‐correlations between magnetic field components exceeded 90% throughout this interval, while the peak cross‐correlations between the dynamic pressure observations was about 70% or better. The main differences were at higher frequencies. However, later after the main cloud had passed the Earth the peak cross‐correlations decreased, especially between ACE at L1 and spacecraft nearer the Earth. Late in the storm the monitors were not observing the same solar wind. We examined the effect of these differences by using our global magnetohydrodynamic simulation to model the magnetosphere using observations from three monitors. Early in the event we found very good agreement between simulated magnetospheres based on input from different solar wind monitors but later the agreement became very bad. If we assume that the monitors near the Earth provide the best measurement of the solar wind that interacts with the magnetosphere, then later in the magnetic storm the solar wind observations at ACE were not a good indication of the solar wind reaching the Earth.
Quarter‐wave modes of standing Alfvén waves detected by cross‐phase analysis
Authors: Obana Yuki , Menk Frederick W. , Sciffer Murray D. , Waters Colin L.
Published: August 2008

We have examined the diurnal variation of the local field line eigenfrequency at L ∼ 2.6 using cross‐phase analysis of Sub‐Auroral Magnetometer Network and Magnetometers Along the Eastern Atlantic Seaboard for Undergraduate Research and Education ground magnetometer array data. On several days the eigenfrequency was remarkably low near the dawn terminator, when one end of the field line was sunlit and the other end was in darkness. Later in the morning the eigenfrequency gradually increased to the normal daytime value. This type of diurnal eigenfrequency variation was found in both European and American meridians and in several seasons (March, June, and December). By modeling this situation we show that the extraordinarily low eigenfrequency events appeared when the ionospheric Pedersen conductance was strongly asymmetric between both ends of the field line, leading to the formation of quarter‐wavelength‐mode standing waves that revert to half‐wavelength modes as the dawn terminator passes both conjugate points. Ground‐based magnetometer measurements of local toroidal field line eigenfrequencies are often inverted to infer plasma mass density in the magnetosphere by assuming half‐wavelength‐mode standing field line oscillations. However, the mode structure and hence field line eigenfrequency also depend on the ionospheric conductance. In particular, we find that there is a threshold of interhemispheric conductance ratio for the quarter‐wavelength mode to be established. Our results therefore show that cross‐phase techniques can detect quarter‐wavelength‐mode waves, where the inferred mass density would be overestimated.
Evidence for plate motion related strain in the Indian shield from shear wave splitting measurements
Authors: Kumar M. Ravi , Singh Arun
Published: August 2008

The predominantly Precambrian Indian lithospheric plate experienced a long history of deformation ever since its breakup from Gondwanaland and its passage over four hot spots. The nature of mantle deformation of this fast moving plate has hitherto remained elusive in view of the paucity of measurements of shear wave anisotropy. In this paper we present the first results of 182 measurements of azimuthal ansiotropy obtained by analyzing the SKS and SKKS waveforms from 85 earthquakes recorded at 35 broadband seismic stations located on various geological units of the Indian shield. Results show that the delay times (δt) between the fast and slow axes of anisotropy are close to 1s, which is the global average for continental shield regions. The fast axis azimuths do not reveal coherent patterns that suggest dominance of asthenospheric flow where a basally flat Indian lithosphere is dragged over an inactive sublithospheric mantle. The northern part of the Indian shield where the lithosphere is thick shows a strong correlation between plate motion and azimuths of fast polarization, due to the effect of the basal cratonic keel plowing through the sublithospheric mantle. Most of the fast axes azimuths can be explained by the absolute plate motion (APM) related strain, considering the basal topography of the lithosphere. The consistent NS orientations along the west coast may be due to edge flow associated with a transition from a thicker to a thinner lithosphere. The Southern Granulite Terrain and the Cuddapah basin shows evidences for fossilized anisotropy, particularly in regions close to continental shear zones.
Upper mantle magma storage and transport under a Canarian shield‐volcano, Teno, Tenerife (Spain)
Authors: Longpré Marc‐Antoine , Troll Valentin R. , Hansteen Thor H.
Published: August 2008

We use clinopyroxene‐liquid thermobarometry, aided by petrography and mineral major element chemistry, to reconstruct the magma plumbing system of the late Miocene, largely mafic Teno shield‐volcano on the island of Tenerife. Outer rims of clinopyroxene and olivine phenocrysts show patterns best explained by decompression‐induced crystallization upon rapid ascent of magmas from depth. The last equilibrium crystallization of clinopyroxene occurred in the uppermost mantle, from ∼20 to 45 km depth. We propose that flexural stresses or, alternatively, thermomechanical contrasts create a magma trap that largely confines magma storage to an interval roughly coinciding with the Moho at ∼15 km and the base of the long‐term elastic lithosphere at ∼40 km below sea level. Evidence for shallow magma storage is restricted to the occurrence of a thick vitric tuff of trachytic composition emplaced before the Teno shield‐volcano suffered large‐scale flank collapses. The scenario developed in this study may help shed light on some unresolved issues of magma supply to intraplate oceanic volcanoes characterized by relatively low magma fluxes, such as those of the Canary, Madeira and Cape Verde archipelagoes, as well as Hawaiian volcanoes in their postshield stage. The data presented also support the importance of progressive magmatic underplating in the Canary Islands.
A climatological study of the sea and land breezes in the Arabian Gulf region
Authors: Eager Rebecca E. , Raman Sethu , Wootten Adrienne , Westphal Douglas L. , Reid Jeffrey S. , Al Mandoos Abdulla
Published: August 2008

This study focuses on observations of the sea and land breeze circulations in the southern Arabian Gulf. During the summer months, the Indian monsoon creates light northwesterly winds over the Arabian Gulf, allowing for the formation of thermally driven circulations. Observations from a network of stations are used to develop a wind climatology for the Arabian Gulf region. Characteristics of the sea and land breeze circulations, such as onset time, duration, and horizontal and vertical extent are described. The dense network of surface stations in the United Arab Emirates (UAE) allows for a fine‐scale observational study in this region. It is found that the sea breeze occurs during all seasons of the year in this region. It occurs in the late afternoon and continues through the evening. A land breeze sets in during the night. Surface offshore winds in the land breeze are strong probably due to drainage flow down the inland hills.
Objective global ocean biogeographic provinces
Authors: Oliver Matthew J. , Irwin Andrew J.
Published: August 2008

Biogeographic provinces are categories used for comparing and contrasting biogeochemical processes and biodiversity between ocean regions. Provinces provide a framework for reasonable extrapolation of point or transect data to broader areas. However, their use is limited due to the non‐automatic, subjective nature of province classification. Furthermore, it is unknown how province boundaries respond to seasonal and climate forcing. These issues make province related hypotheses difficult to test with static provinces. To solve this problem, we use objective classification on global remote sensing data to automatically produce time and space resolved ocean provinces. Seasonal patterns in province geography reflect well‐known ocean processes. Our predictions of province boundaries are verified by in‐situ ship track data and province distributions in the equatorial Pacific correlate well with ENSO indexes. This objective classification system captures spatial and temporal province dynamics and provides objective categories for cross‐province biogeochemical hypotheses to be rigorously tested.
Interannual and latitudinal variability of the thermosphere density annual harmonics
Authors: Guo Jianpeng , Wan Weixing , Forbes Jeffrey M. , Sutton Eric , Nerem R. Steven , Bruinsma Sean
Published: August 2008

In this paper we investigate the intra‐annual variation in thermosphere neutral density near 400 km using 4 years (2002–2005) of CHAMP measurements. The intra‐annual variation, commonly referred to as the “semiannual variation,” is characterized by significant latitude structure, hemispheric asymmetries, and interannual variability. The magnitude of the maximum yearly difference, from the yearly minimum to the yearly maximum, varies by as much as 60% from year to year, and the phases of the minima and maxima also change by 20–40 days from year to year. Each annual harmonic of the intra‐annual variation, namely, annual, semiannual, terannual and quatra‐annual, exhibits a decreasing trend from 2002 through 2005 that is correlated with the decline in solar activity. In addition, some variations in these harmonics are correlated with geomagnetic activity, as represented by the daily mean value of Kp. Recent empirical models of the thermosphere are found to be deficient in capturing most of the latitude dependencies discovered in our data. In addition, the solar flux and geomagnetic activity proxies that we have employed do not capture some latitude and interannual variations detected in our data. It is possible that these variations are partly due to other effects, such as seasonal‐latitudinal variations in turbopause altitude (and hence O/N2 composition) and ionosphere coupling processes that remain to be discovered in the context of influencing the intra‐annual variations depicted here. Our results provide a new data set to challenge and validate thermosphere‐ionosphere general circulation models that seek to delineate the thermosphere intra‐annual variation and to understand the various competing mechanisms that may contribute to its existence and variability. We furthermore suggest that the term “intra‐annual” variation be adopted to describe the variability in thermosphere and ionosphere parameters that is well‐captured through a superposition of annual, semiannual, terannual, and quatra‐annual harmonic terms, and that “semiannual” be used strictly in reference to a pure 6‐monthly sinusoidal variation. Moreover, we propose the term “intraseasonal” to refer to those shorter‐term variations that arise as residuals from the above Fourier representation.
Intra-mammary single infusion of casein hydrolyzate in dairy cows as alternative dry period treatment: Curing bacterial infection and increasing milk yield in the subsequent lactations
Authors: Silanikove Nissim , Yacoby Shamay , Leitner Gabriel
Published: August 2008

Conclusions:

This study sustain previous results that treatment with CNH is a powerful mean to eradicated bacterial infection, and strongly highlight the potential of this method to serve as a viable non-antibiotic dry cow therapy treatment. The increase in milk yield is a valuable bonus and its effectiveness is comparable with that achieved with growth hormone treatment, albeit in much simple mode of treatment and without the problematic of hormonal treatment.
Silencing of MBD1 and MeCP2 in prostate-cancer-derived PC3 cells produces differential gene expression profiles and cellular phenotypes
Authors: Yaqinuddin Ahmed , Abbas Farhat , Naqvi Syed Z. , Bashir Mohammad U. , Qazi Romena , Qureshi Sohail A.
Published: August 2008

Alterations in genomic CpG methylation patterns have been found to be associated with cell transformation and neoplasia. Although it is recognized that methylation of CpG residues negatively regulates gene expression, how the various MBPs (methyl-binding proteins) contribute to this process remains elusive. To determine whether the two well characterized proteins MeCP2 (methyl-CpG-binding protein 2) and MBD1 (methyl-CpG-binding domain 1) have distinct or redundant functions, we employed RNAi (RNA interference) to silence their expression in the prostate cancer-derived PC3 cell line, and subsequently compared cell growth, invasion and migration properties of these cell lines in addition to their respective mRNA-expression profiles. Cells devoid of MeCP2 proliferated more poorly compared with MBD1-deficient cells and the parental PC3 cells. Enhanced apoptosis was observed in MeCP2-deficient cells, whereas apoptosis in parental and MBD1-deficient cells appeared to be equivalent. Boyden chamber invasion and wound-healing migration assays showed that MBD1-silenced cells were both more invasive and migratory compared with MeCP2-silenced cells. Finally, gene chip microarray analyses showed striking differences in the mRNA-expression profiles obtained from MeCP2- and MBD1-depleted cells relative to each other as well as when compared with control cells. The results of the present study suggest that MeCP2 and MBD1 silencing appear to affect cellular processes independently in vivo and that discrete sets of genes involved in cellular proliferation, apoptosis, invasion and migration are targeted by each protein.
Accompanying a Client on His Therapy Journey
Authors: Pelczarski Kristin M. , Yaruss J. Scott
Published: August 2008

This paper discusses the “journey” that clients take when entering therapy, and some of the challenges they may face along the way. Various roadblocks, such as the need to practice therapy skills, unrealistic expectations about outcomes of therapy, and the difficulty of the journey can cause the client to stumble along the path and, thereby, minimize the client’s chances of success. This paper emphasizes how the clinician must be attuned to the client to help him benefit from therapy and how the clinician must remain flexible in order to adapt to the changes that occur as a speaker’s journey unfolds.
Models for randomly hyperbranched polymers: Theory and simulation
Authors: Konkolewicz Dominik , Thorn-Seshold Oliver , Gray-Weale Angus
Published: August 2008

We derive theoretical models for the structures of randomly hyperbranched polymers in solution, and test them against computer simulations. The models are based on the same basic approach: Building a structure by the random assembly of “simple units,” which may be monomers, linear chains, or larger branched species. Comparisons to simulation reported here show that the conformations of hyperbranched species, i.e., their radii of gyration and full density profiles, are accurately described by this approach. These stringent tests complement previous tests against experiment. We include the effects of solvent quality at the mean-field level. Our model works best for hyperbranched structures, but also reproduces very well the simulated density profiles of dendrimers. The models reported here provide a simple, but realistic, picture of the physical influences that affect the conformations of hyperbranched species.
Data evaluation of laminar flow diffusion chamber nucleation experiments with different computational methods
Authors: Mitrakos D. , Ždímal V. , Brus D. , Housiadas C.
Published: August 2008

In order to evaluate the experimental data from laminar flow diffusion chamber (LFDC) experiments on homogeneous nucleation, an extensive postmeasurement computational analysis is required. The present work investigates the influence of the used computational methodology on the derived nucleation curves. To this end a reanalysis is made of previous LFDC experiments of 1-butanol nucleation in helium [D. Brus et al., J. Chem. Phys. 122, 214506 (2005)] using two different methods. The first method is based on single fluid heat and vapor transport in the carrier gas ignoring the aerosol processes, as commonly made in LFDC data evaluations. The second method is more comprehensive as is based on multidimensional computational fluid-particle dynamics. The calculations are made under the usual simplification of one-way coupling between fluid flow and particles, which is a valid approximation in most practical aerosols, while full aerosol dynamical effects are accommodated. Similar results were produced by the two methods. This finding corroborates the usual practice of omitting aerosol calculations in LFDC experimental data evaluation.
Exact density functional theory for ideal polymer fluids with nearest neighbor bonding constraints
Authors: Woodward Clifford E. , Forsman Jan
Published: August 2008

We present a new density functional theory of ideal polymer fluids, assuming nearest-neighbor bonding constraints. The free energy functional is expressed in terms of end site densities of chain segments and thus has a simpler mathematical structure than previously used expressions using multipoint distributions. This work is based on a formalism proposed by Tripathi and Chapman [Phys. Rev. Lett. 94, 087801 (2005)]. Those authors obtain an approximate free energy functional for ideal polymers in terms of monomer site densities. Calculations on both repulsive and attractive surfaces show that their theory is reasonably accurate in some cases, but does differ significantly from the exact result for longer polymers with attractive surfaces. We suggest that segment end site densities, rather than monomer site densities, are the preferred choice of “site functions” for expressing the free energy functional of polymer fluids. We illustrate the application of our theory to derive an expression for the free energy of an ideal fluid of infinitely long polymers.
A new potential energy surface for OH(A Σ2+)–Ar: The van der Waals complex and scattering dynamics
Authors: Kłos J. , Alexander M. H. , Brouard M. , Eyles C. J. , Aoiz F. J.
Published: August 2008

New ab initio studies of the OH(A Σ2+)–Ar system reveal significantly deeper potential energy wells than previously believed, particularly for the linear configuration in which Ar is bound to the oxygen atom side of OH(A Σ2+). In spite of this difference with previous ab initio work, bound state calculations based on a new RCCSD(T) potential energy surface yield an energy level structure in reasonable accord with previous theoretical and experimental studies. Preliminary open and closed shell quantum mechanical and quasiclassical trajectory scattering calculations are also performed on the new potential energy surface surface. The findings are discussed in the light of previous theoretical and experimental results for rotational energy transfer in collisions of OH(A Σ2+) with Ar.
Novel synchronization of discrete-time chaotic systems using neural network observer
Authors: Naghavi S. V. , Safavi A. A.
Published: August 2008

This paper presents a new approach to solve the synchronization problem of a large class of discrete chaotic systems. The chaotic systems can be reformulated as an appropriate class of linear parameter varying (LPV) systems. The synchronization problem for this class of nonlinear systems is revisited from a control perspective and it is argued that the problem can be viewed as an observer design problem. Then, based on the LPV representation, a neural network observer-based approach is proposed to solve the synchronization problem. The simulation results show the advantages of combining the LPV techniques and the neural networks to determine the appropriate observer gain within the context of chaotic system synchronization.
Lumped element-based, highly sub-wavelength, negative index metamaterials at UHF frequencies
Authors: Erentok Aycan , Ziolkowski Richard W. , Nielsen J. A. , Greegor R. B. , Parazzoli C. G. , Tanielian M. H. , Cummer Steven A. , Popa Bogdan-Ioan , Hand Thomas , Vier D. C. , Schultz S.
Published: August 2008

Several lumped element-based epsilon-negative (ENG), mu-negative (MNG), and double-negative (DNG) metamaterial designs have been developed for operation at 400 MHz in the UHF frequency band. The use of lumped elements enabled the creation of highly sub-wavelength unit cells whose overall size was λ0/d∼75 at 400 MHz. The measured negative index material (NIM) showed an effective real index of refraction nreal=−3.11 with a total loss that was less than 1 dB/cm. The NIM bandwidth was >10% in the neighborhood of 400 MHz.
Electrical detection of biomaterials using AlGaN/GaN high electron mobility transistors
Authors: Kang B. S. , Wang H. T. , Ren F. , Pearton S. J.
Published: August 2008

Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte. Different methods, including gas chromatography, chemiluminescence, selected ion flow tube, and mass spectroscopy, have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors (HEMTs). HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas (2DEG) mobility and saturation velocity. The conducting 2DEG channel of AlGaN/GaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. HEMT sensors can be used for detecting gases, ions, pH values, proteins, and DNA. In this paper we review recent progress on functionalizing the surface of HEMTs for specific detection of glucose, kidney marker injury molecules, prostate cancer, and other common substances of interest in the biomedical field.
Direct observations of thermally induced structural changes in amorphous silicon carbide
Authors: Ishimaru Manabu , Hirata Akihiko , Naito Muneyuki , Bae In-Tae , Zhang Yanwen , Weber William J.
Published: August 2008

Thermally induced structural relaxation in amorphous silicon carbide (SiC) has been examined by means of in situ transmission electron microscopy (TEM). The amorphous SiC was prepared by high-energy ion beam irradiation into a single crystalline 4H-SiC substrate. Cross-sectional TEM observations and electron energy-loss spectroscopy measurements revealed that thermal annealing induces a remarkable volume reduction, so-called densification, of amorphous SiC. From radial distribution function analyses using electron diffraction, notable changes associated with structural relaxation were observed in chemical short-range order. It was confirmed that the structural changes observed by the in situ TEM study agree qualitatively with those of the bulk material. On the basis of the alteration of chemical short-range order, we discuss the origin of thermally induced densification in amorphous SiC.
Temperature-dependent growth and transient state of hydrogen-induced nanocavities in silicon
Authors: Kinomura A. , Suzuki R. , Ohdaira T. , Muramatsu M. , He C. , Oshima N. , Matsumoto T. , Tanoue H. , Horino Y.
Published: August 2008

Silicon samples H-implanted to a dose of 3×1016 cm−2 were analyzed by positron annihilation and ion backscattering techniques to investigate the growth of H-induced nanocavities at different annealing temperatures (400–900 °C). Positron annihilation lifetime spectroscopy revealed a constant increase in the vacancy cluster size (i.e., nanocavity size) as the annealing temperature increased. On the other hand, Doppler broadening and ion channeling measurements suggested strong interaction between the implanted H and the defects depending on the annealing temperature. Furthermore, Au-gettering experiments revealed that transient gettering sites are formed at 600 °C between the H projected range and the surface. These results indicated that H desorption is one of the key factors in the optimization of the gettering process with H-induced nanocavities.
High sensitivity two-frequency paired polarized interferometer in Faraday rotation angle measurement of ambient air with single-traveling configuration
Authors: Lin Chu-En , Yu Chih-Jen , Li Ying-Chang , Tsai Chien-Chung , Chou Chien
Published: August 2008

High sensitivity detection on Faraday rotation and Verdet constant of ambient air under weak applied magnet field and single-pass configuration specimen is setup in which a two-frequency paired linear polarized interferometer (TPPI) coupled with balanced detector shown at shot-noise-limited detection is demonstrated. The Verdet constant of ambient air at 1.3×10−6 rad/mT m and its sensitivity at 4.3×10−8 rad/mT m were measured. Additionally, this method also is able to extend into a broad spectral range on Faraday rotation angle or Verdet constant measurement. Finally, the enhancement on detection sensitivity by integrating a Fabry–Pérot cavity into TPPI is discussed.
Magnetocaloric response of FeCrB amorphous alloys: Predicting the magnetic entropy change from the Arrott–Noakes equation of state
Authors: Franco V. , Conde A. , Kiss L. F.
Published: August 2008

The magnetic entropy change in Fe92−xCr8Bx (x=12,15) amorphous alloys has been studied. Increasing the B content, both the peak entropy change and the Curie temperature of the alloy increase. This is in agreement with an increase in the average magnetic moment per iron atom. The thermal and field dependences of the magnetic entropy change curves have been analyzed with the use of the Arrott–Noakes equation of state. It is shown that determining the parameters in this equation of state (through fitting the magnetization data) allows prediction of the field and temperature dependences of the magnetic entropy change curves in a broad temperature range around the Curie temperature.
Tight-binding calculations of ZnSe/Si wurtzite superlattices: Electronic structure and optical properties
Authors: Laref A. , Sekkal W. , Laref S. , Luo S. J.
Published: August 2008

Our study is devoted to the theoretical investigation of the electronic and optical properties of (ZnSe)n/(Si2)m (0001) wurtzite (WZ) superlattices (SLs) with the range n=m=1–18, giving special attention to the role of interface states at the Zn–Si and Se–Si polar interfaces. The calculations are performed by means of a semiempirical tight-binding model with an sp3s∗ basis. The procedure involves the construction of a tight-binding Hamiltonian model of WZ SLs from the WZ bulk in the (0001) direction with different n and m layers. For (ZnSe)16/(Si2)16 SL, we found that the energy band gap is close to 1.665 eV, with the conduction-band minimum located at the Γ point. The states at the conduction- and valence-band edges are confined two dimensionally in the Si layers. For a valence-band discontinuity ΔEv=1.09 eV given by Harrison theory, the band gap between the confined band edges states increases (2.37 eV at the Γ point for n=m=2) by decreasing the superlattice period. It is shown that the heterointerface bond relaxation strongly affects interface band in the band gap. In the (ZnSe)10/(Si2)10 SL, the relaxed Si bonds at the heterointerface induce a vacant interface band and a filled interface band in the band gap. The band structures of (ZnSe)n/(Si2)m (0001) (WZ) (SLs) with different layer thickness are used to determine the electron and hole effective masses. Furthermore, the calculated absorption spectra of the superlattices are found to be quite different from those of bulk ZnSe and Si but fairly close to their average. The electronic structure of the superlattice turns out to be quite sensitive to the combination of the well and barrier layer thickness. This sensitivy suggests the possibility of designing suitable band structures for device application.
Enhanced nonlinear magnetic resonance signals via square wave dipolar fields
Authors: Branca R. T. , Galiana G. , Warren W. S.
Published: August 2008

This report introduces a new approach that enhances nonlinear solution magnetic resonance signals from intermolecular dipolar interactions. The resulting signals can theoretically be as large as the full equilibrium magnetization. Simple, readily implemented pulse sequences using square-wave magnetization modulation simultaneously refocus all even order intermolecular multiple quantum coherences, leading to a substantial net signal enhancement, complex nonlinear dynamics, and improved structural sensitivity under realistic conditions.
The search for mechanically stable PbTe based thermoelectric materials
Authors: Gelbstein Yaniv , Dashevsky Zinovi , Dariel Moshe P.
Published: August 2008

The search for alternative energy sources is nowadays at the forefront of applied research. In this context, thermoelectricity for direct energy conversion from thermal to electrical energy plays an important role, in particular, for the exploitation of waste heat [G. J. Snyder and E. S. Toberer, Nat. Mater. 7, 105 (2008); M. S. Dresselhaus et al., Adv. Mater. (Weinheim, Ger.) 19, 1043 (2007)]. Materials for such applications should exhibit thermoelectric potential as well as mechanical stability. PbTe based alloys have been considered for many years as state of the art thermoelectric materials for mid-temperature power generation (500–900 K), with efficiency values that are still being improved by both alloying [P. F. P. Poudeu et al., Chem., Int. Ed. 45, 1 (2006); J. R. Sootsman et al., Chem. Mater. 18, 4993 (2006); P. F. P. Poudeu et al., Chem. Soc. 126, 14347 (2006); J. Androulakis et al., Adv. Mater. (Weinheim, Ger.) 18, 1170 (2006); K. F. Hsu et al., Science 303, 818 (2004)] and doping [Y. Gelbstein et al., Physica B (Amsterdam) 363, 196 (2005); Y. Gelbstein et al., Physica B (Amsterdam) 396, 16 (2007)] optimizations. However, the mechanical properties of PbTe based materials are highly dependent on the conductivity type (n or p) and carrier concentrations [Y. Gelbstein et al., Scr. Mater. 58, 251 (2008)]. This paper puts forward the mechanical durability of thermoelectric materials and, in particular, of PbTe as a dominant factor that is nondetachable from the transport properties, which should be considered in the search for high quality thermoelectric materials. Here we discuss the microhardness enhancement of p-type PbTe alloys with hole concentrations higher than 5×1018 cm−3. This anomaly is obtained while all the other investigated n-type (up to 1020 cm−3) and p-type (up to 1018 cm−3) compositions maintained a constant microhardness value of ∼30 HV. The origin of this microhardness enhancement is not yet understood on a fundamental level, however two possible mechanisms are discussed. One deals with the elastic interaction between dislocations and impurities with higher covalent radius than the sublattice vacancy. The other is correlated with the existence of a second valence band of heavy holes in PbTe, which begins to fill up at the same concentration where a hardness enhancement was observed. These mechanisms correlating between mechanical end electronic properties of PbTe based alloys can serve as guidelines for the search for potential candidates, obtaining both thermoelectric potential and mechanical stability for thermoelectric applications.
Effects of surface-group length on liquid defiltration in a MCM-41
Authors: Kim Taewan , Han Aijie , Qiao Yu
Published: August 2008

The confined liquid in mobile crystalline material (MCM)-41 modified by short surface groups can defiltrate as the external pressure is reduced, while in MCM-41 modified by long surface groups it cannot, which can be attributed to the variation in effective nanopore size and the associated energy barrier to molecular motion.
Plasma-enabled growth of ultralong straight, helical, and branched silica photonic nanowires
Authors: Huang S. Y. , Ostrikov K. , Xu S.
Published: August 2008

This article reports on the low-temperature inductively coupled plasma-enabled synthesis of ultralong (up to several millimeters in length) SiO2 nanowires, which were otherwise impossible to synthesize without the presence of a plasma. Depending on the process conditions, the nanowires feature straight, helical, or branched morphologies. The nanowires are amorphous, with a near-stoichiometric elemental composition ([O]/[Si]=2.09) and are very uniform throughout their length. The role of the ionized gas environment is discussed and the growth mechanism is proposed. These nanowires are particularly promising for nanophotonic applications where long-distance and channelled light transmission and polarization control are required.
Development of a combined K-edge subtraction and fluorescence subtraction imaging system for small animals
Authors: Bewer Brian , Zhang Honglin , Zhu Ying , Zhang Limei , George Graham N. , Pickering Ingrid J. , Chapman Dean
Published: August 2008

A novel combined imaging system for small animals using dilute concentrations of iodine as a contrast agent was developed for wide and pencil photon beam image acquisitions. This combined imaging system used K-edge subtraction (KES) and fluorescence subtraction imaging (FSI) and was tested at the Hard x-ray Microanalysis beamline at the Canadian Light Source. The initial wide beam KES image acquired with a charge-coupled device camera was used to identify regions of interest for further investigation and determine the location and area of the raster scan for pencil beam imaging. The pencil photon beam scanning mode acquired simultaneously KES and FSI measurements with an ionization chamber measuring the KES data and a multielement germanium detector measuring the FSI data. A description of the system is given as well as preliminary results using an iodine test object.
The molecular mechanism of lipid monolayer collapse
Authors: Baoukina Svetlana , Monticelli Luca , Risselada H. Jelger , Marrink Siewert J. , Tieleman D. Peter
Published: August 2008

Lipid monolayers at an air–water interface can be compressed laterally and reach high surface density. Beyond a certain threshold, they become unstable and collapse. Lipid monolayer collapse plays an important role in the regulation of surface tension at the air–liquid interface in the lungs. Although the structures of lipid aggregates formed upon collapse can be characterized experimentally, the mechanism leading to these structures is not fully understood. We investigate the molecular mechanism of monolayer collapse using molecular dynamics simulations. Upon lateral compression, the collapse begins with buckling of the monolayer, followed by folding of the buckle into a bilayer in the water phase. Folding leads to an increase in the monolayer surface tension, which reaches the equilibrium spreading value. Immediately after their formation, the bilayer folds have a flat semielliptical shape, in agreement with theoretical predictions. The folds undergo further transformation and form either flat circular bilayers or vesicles. The transformation pathway depends on macroscopic parameters of the system: the bending modulus, the line tension at the monolayer–bilayer connection, and the line tension at the bilayer perimeter. These parameters are determined by the system composition and temperature. Coexistence of the monolayer with lipid aggregates is favorable at lower tensions of the monolayer–bilayer connection. Transformation into a vesicle reduces the energy of the fold perimeter and is facilitated for softer bilayers, e.g., those with a higher content of unsaturated lipids, or at higher temperatures.
Bcl2L12-mediated inhibition of effector caspase-3 and caspase-7 via distinct mechanisms in glioblastoma
Authors: Stegh Alexander H. , Kesari Santosh , Mahoney John E. , Jenq Harry T. , Forloney Kristin L. , Protopopov Alexei , Louis David N. , Chin Lynda , DePinho Ronald A.
Published: August 2008

Glioblastoma multiforme (GBM) is a highly aggressive brain cancer that is characterized by the paradoxical features of intense apoptosis resistance yet a marked propensity to undergo necrosis. Bcl2L12 (for Bcl2-Like12) is a nuclear and cytoplasmic oncoprotein that is universally overexpressed in primary GBM and functions to block postmitochondrial apoptosis signaling by neutralizing effector caspase-3 and caspase-7 maturation. This postmitochondrial block in apoptosis engenders the alternate cell fate of cellular necrosis, thus providing a molecular explanation for GBM's classical features. Whereas Bcl2L12-mediated neutralization of caspase-7 maturation involves physical interaction, the mechanism governing Bcl2L12-mediated inhibition of caspase-3 activity is not known. The nuclear localization of Bcl2L12 prompted expression profile studies of primary astrocytes engineered to overexpress Bcl2L12. The Bcl2L12 transcriptome revealed a striking induction of the small heat shock protein α-basic-crystallin (αB-crystallin/HspB5), a link reinforced by robust αB-crystallin expression in Bcl2L12-expressing orthotopic glioma and strong coexpression of αB-crystallin and Bcl2L12 proteins in human primary GBMs. On the functional level, enforced αB-crystallin or Bcl2L12 expression enhances orthotopic tumor growth. Conversely, RNAi-mediated knockdown of αB-crystallin in Bcl2L12-expressing astrocytes and glioma cell lines with high endogenous αB-crystallin showed enhanced apoptosis, yet decreased necrotic cell death with associated increased caspase-3 but not caspase-7 activation. Mirroring this specific effect on effector caspase-3 activation, αB-crystallin selectively binds pro-caspase-3 and its cleavage intermediatesin vitroandin vivo. Thus, αB-crystallin is a Bcl2L12-induced oncoprotein that enables Bcl2L12 to block the activation of both effector caspases via distinct mechanisms, thereby contributing to GBM pathogenesis and its hallmark biological properties.
Orientation dependence in fluorescent energy transfer between Cy3 and Cy5 terminally attached to double-stranded nucleic acids
Authors: Iqbal Asif , Arslan Sinan , Okumus Burak , Wilson Timothy J. , Giraud Gerard , Norman David G. , Ha Taekjip , Lilley David M. J.
Published: August 2008

We have found that the efficiency of fluorescence resonance energy transfer between Cy3 and Cy5 terminally attached to the 5′ ends of a DNA duplex is significantly affected by the relative orientation of the two fluorophores. The cyanine fluorophores are predominantly stacked on the ends of the helix in the manner of an additional base pair, and thus their relative orientation depends on the length of the helix. Observed fluorescence resonance energy transfer (FRET) efficiency depends on the length of the helix, as well as its helical periodicity. By changing the helical geometry from B form double-stranded DNA to A form hybrid RNA/DNA, a marked phase shift occurs in the modulation of FRET efficiency with helix length. Both curves are well explained by the standard geometry of B and A form helices. The observed modulation for both polymers is less than that calculated for a fully rigid attachment of the fluorophores. However, a model involving lateral mobility of the fluorophores on the ends of the helix explains the observed experimental data. This has been further modified to take account of a minor fraction of unstacked fluorophore observed by fluorescent lifetime measurements. Our data unequivocally establish that Förster transfer obeys the orientation dependence as expected for a dipole–dipole interaction.