bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of rosemary (Rosmarinus officinalis, L.) on plant sterol oxidation in extra virgin olive oil
Authors: D'Evoli Laura , Huikko Laura , Lampi Anna‐Maija , Lucarini Massimo , Lombardi‐Boccia Ginevra , Nicoli Stefano , Piironen Vieno
Published: August 2006

The objective of this study was to investigate the potential role of rosemary compounds in inhibiting the plant sterol oxidation in extra virgin olive oil during heating. The stability of plant sterols was measured by quantification of plant sterol and sterol oxide formation upon 6 h of heating in both the extra virgin olive oil and its respective oil at 10% rosemary concentration (ROE). The total sterol and sitosterol oxide contents were determined by GC‐flame ionization detection (GC‐FID) and GC‐MS techniques, respectively. Heating experiments were carried out at 180°C for 0, 1, 3 and 6 h. The total sterol content in the extra virgin olive oil was 255 mg/100 g and that in the ROE 270 mg/100 g. Sitosterol was the most abundant sterol in both samples (50% of total sterol). The ROE showed a lower content of sitosterol oxides with respect to the extra virgin olive oil during heating: after 6 h of heating only 6.1% of sitosterol oxides were formed, while up to 11.5% of sitosterol oxidized in the extra virgin olive oil. Our findings suggested that rosemary compounds were able to counteract the oxidation of plant sterols in the extra virgin olive oil during heating, preventing formation of potentially harmful compounds to human health.
Systemic sclerosis fibroblasts inhibit in vitro angiogenesis by MMP‐12‐dependent cleavage of the endothelial cell urokinase receptor
Authors: Serratì S , Cinelli M , Margheri F , Guiducci S , Del Rosso A , Pucci M , Fibbi G , Bazzichi L , Bombardieri S , Matucci‐Cerinic M , Del Rosso M
Published: August 2006

Failure of endothelial cells to develop new vessels in response to hypoxia is a distinctive feature of systemic sclerosis (SSc) in the avascular phase. We have previously shown that SSc endothelial cells over‐express matrix metalloproteinase‐12 (MMP‐12), which blocks angiogenesis by cleavage of the endothelial urokinase‐type plasminogen activator receptor (uPAR). In the present study, we have investigated whether over‐expression of MMP‐12 and of angiostatic factors, or hypo‐expression of angiogenic factors by SSc fibroblasts, contributes to impaired angiogenesis in SSc. Dermal fibroblasts were isolated from healthy subjects (N‐Fb) and patients with diffuse SSc (SSc‐Fb). Angiogenesis of target normal human microvascular endothelial cells (H‐MVECs) was assayed by Matrigel invasion, cell proliferation, and capillary morphogenesis. uPAR cleavage and MMP‐12 activity were evaluated by western blotting. We show that the over‐expression of MMP‐12 by SSc‐Fb determines uPAR cleavage in H‐MVECs. Conditioned medium from SSc‐Fb impaired H‐MVEC proliferation, invasion, and capillary morphogenesis. Anti‐MMP‐12 antibodies restored such impairment. Altered expression of angiostatic/angiogenic factors, including transforming growth factor β1, did not account for SSc‐Fb‐dependent impairment of angiogenesis. The over‐expression of MMP‐12 by both SSc‐Fb and SSc endothelial cells indicates that MMP‐12 over‐production may have a critical pathogenic role in SSc‐associated vascular alterations. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Antidepressant drugs: prevalence, incidence and indication of use in general practice of Southern Italy during the years 2003–2004
Authors: Trifirò Gianluca , Barbui Corrado , Spina Edoardo , Moretti Salvatore , Tari Michele , Alacqua Marianna , Caputi Achille P , Arcoraci Vincenzo
Published: August 2006

Purpose

To estimate 1‐year prevalence, 1‐year incidence and indication of use of antidepressant (AD) drug treatment in general practice of Southern Italy during the years 2003–2004.

Methods

Among 142 346 individuals registered in the lists of 119 general practitioners of Southern Italy, we identified users of different AD types: tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs) and other antidepressants. Annual prevalence of AD use was measured as the number of individuals receiving at least one AD prescription in the years 2003–2004, divided by the number of patients registered in the general practitioner (GP) lists. One‐year incidence of AD treatment was calculated as the number of new users of AD, divided by the number of total patients free from AD prescriptions in the previous year.

Results

Overall, 1‐year prevalence of AD use was 5.08 (95% confidence interval (CI): 4.97–5.20) per 100 inhabitants in the year 2003, with a 20% increase in 2004 (6.00, 5.88–6.13). Prevalence of SSRI use markedly increased from 3.80 (3.73–3.90) in 2003 to 4.51 (4.40–4.61) in 2004. The incidence rates of SSRI, TCA and other antidepressant use were 2.11 (2.03–2.19), 0.38 (0.35–0.41) and 0.53 (0.49–0.57) respectively. Depressive disorders were the main indication of use of any AD user (mostly for SSRI users), followed by anxious disturbances.

Conclusions

SSRIs, particularly those recently marketed, have been increasingly used during the last years, mainly to treat affective disorders. Copyright © 2006 John Wiley & Sons, Ltd.
Social support and adolescent cancer survivors: a review of the literature
Authors: Decker Carol L.
Published: August 2006

With survival rates increasing dramatically in pediatric cancer, concern has increasingly focused on the psychosocial aspects of the cancer experience. Clearly, the experience of a cancer diagnosis and treatment of cancer places high demands on the coping of adolescents. Research has shown social support to be effective in decreasing stress and enhancing coping in adolescents facing such demands. A review and critical analysis of studies of social support in adolescent cancer survivors was conducted. The seventeen studies were mainly descriptive and exploratory in nature with social support examined for a number of outcome variables in eight of the studies. Findings from this review indicate that support from parents (especially the mother) and friends were extremely important and that the adolescents were satisfied with family support. Support from friends was described as less satisfactory. Methodological concerns of the reviewed studies include small samples and a lack of consistency in the instruments used to assess social support. Future studies of social support for adolescent cancer survivors should include larger samples to determine gender, age group, and ethnic differences and to allow the examination of social support theoretical models specific to the developmental and chronic illness situation of these adolescents. Copyright © 2006 John Wiley & Sons, Ltd.
CASSCF version of density functional theory
Authors: Nakata K. , Ukai T. , Yamanaka S. , Takada T. , Yamaguchi K.
Published: August 2006

An ab initio complete active space self‐consistent field (CASSCF) version of the density functional theory (DFT) approach, based on the partially interacting reference system, is presented. The working equations are similar to those of the CASSCF theory, but include the residual correlation potential. The essential superior points of CASSCF‐DFT, compared with the CAS configuration interaction (CI) DFT, are demonstrated. To this end, the potential curves and binding energies of several diatomic molecules (e.g., H2, Li2, and O2) are investigated in comparison with the experiments. The energy difference between the 6S and 6D states of the Mn atom, together with ionization potentials of Mn atoms, are investigated to demonstrate an important role of the electron repulsion effect. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Multireference density functional theory with orbital‐dependent correlation corrections
Authors: Yamanaka Shusuke , Nakata Kazuto , Ukai Takeshi , Takada Toshikazu , Yamaguchi Kizashi
Published: August 2006

The features of ab initio wave function‐driven multireference (MR)‐density functional theory (DFT) approach based on the partially interacting reference system for ground and excited states are discussed from the viewpoint of a simple classification of electron correlation effects. Our previous MR‐DFT approach covers (i) structure‐free, and (ii) resonating‐type correlations, but does not include (iii) orbital‐dependent correlation effects. Indeed, the computational results of excitation energies of atoms imply that the state‐dependent correlations remain if the CASCI wave functions are used for the wave function part of MR‐DFT and semilocal correlation functional is used. Thus, we present an orbital‐dependent residual correlation for complete active space (CAS) DFT to describe type (iii) of correlation effects. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Resonating broken‐symmetry approach to biradicals and polyradicals
Authors: Takeda R. , Yamanaka S. , Yamaguchi K.
Published: August 2006

We present a resonating broken‐symmetry (RBS) approach for strongly correlated electron systems. This is a nonorthogonal configuration interaction (CI) using symmetry‐broken Hartree–Fock (HF) references. We have applied it to the hydrogen molecule, linear hydrogen chain model systems, and to the fluorine molecule. As is known, spin contamination of biradical system with S = 1/2 can be removed by taking the resonance of two spin‐unrestricted HF (UHF) configurations. In contrast, more configurations were required to do spin projections perfectly in polyradical systems. The implications of the computational results are discussed in relation to the applicability of the RBS molecular orbital (MO) approach to more complex systems, such as metal clusters. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Persistent increase of plasma butyryl/isobutyrylcarnitine concentrations as marker of SCAD defect and ethylmalonic encephalopathy
Authors: Merinero B. , Pérez‐Cerdá C. , Ruiz Sala P. , Ferrer I. , García M. J. , Martínez Pardo M. , Belanger‐Quintana A. , de la Mota J. L. , Martin‐Hernández E. , Vianey‐Saban C. , Bischoff C. , Gregersen N. , Ugarte M.
Published: August 2006

High concentrations of butyryl/isobutyrylcarnitine (C4‐carnitine) in plasma with increase of ethylmalonic acid (EMA) in urine point to different genetic entities, and further investigations are required to differentiate the possible underlying defect. Here we report three unrelated cases, two neurologically affected and one asymptomatic, with this abnormal metabolite pattern due either to mutations in the ETHE1 gene or to a short‐chain acyl‐CoA dehydrogenase (SCAD) defect.
Bilateral nuclear cataracts as the first neonatal sign of Fanconi–Bickel syndrome
Authors: Furlan F. , Santer R. , Vismara E. , Santus F. , Sersale G. , Menni F. , Parini R.
Published: August 2006

A patient with early bilateral nuclear cataracts and subsequent diagnosis of Fanconi–Bickel syndrome is described. Despite impaired galactose and glucose metabolism, cataracts have been reported in only few cases with this disorder. We conclude that Fanconi–Bickel syndrome should be considered in the differential diagnosis of neonatal cataracts. The pathogenesis of this complication has not been fully elucidated.
ANTONIO SQUARCIALUPI: MAN AND MYTH
Authors: Haar James , Nádas John
Published: August 2006

‘… Squarcialupi, a famous organist, but who remains a rather mythical figure’. Of course we know that Antonio degli Organi, as he was called throughout his life, was a real person, and if we trust in the verisimilitude of Benedetto da Maiano's portrait bust of him (made ten years after his death, strongly classicising in design, and altered at least once in the early sixteenth century), we have an idea of what he looked like. Antonio degli Organi (1416–80) was not born with the surname Squarcialupi, nor do we know precisely when or under what circumstances he took this name (but see below). We have enough information about his life to form a preliminary notion of his character, but the mental image we create is not altogether a coherent one. He was organist at Santa Maria del Fiore, the Florentine cathedral, for an extraordinarily long period, from 1432 until his death. This alone makes him a ‘famous organist’; but a good deal of the fame is posthumous, and there is next to no meaningful comment from contemporaries about his playing. He judged the quality and state of repair of organs but is not known to have had organ-building expertise. Antonio presumably taught his son Francesco, who succeeded him at the cathedral on his death and served until his own death in 1509. His only other student of note is the Greek organist Isaac Argyropoulos, whose playing was much admired in Naples, Bologna, Florence and Milan in the 1470s.
PHILIPPE DE MONTE: NEW AUTOBIOGRAPHICAL DOCUMENTS
Authors: Wistreich Richard
Published: August 2006

In a letter written in the year he died, the novelist Italo Calvino spoke of his unease with the writing of the story of his own life: ‘Each time I see my life fixed and objectified I am seized with anxiety, especially when it is notes that I myself have supplied … by repeating the same things [but] using different words I always hope to get round my neurotic relationship with autobiography.’ Such testimony from a still-living creative artist is a valuable reminder of the historiographical conundrums of even the most apparently ‘authentic’ biographical narrative. Those of us who read, research and write the stories of long-dead artists, relying as we must on the contents of documents both written and preserved for all kinds of forgotten and quite likely unfathomable reasons, have learnt to be cautious, if not a little anxious, in our relationships with what they seem to be saying to us. The more consciously autobiographical such writings appear to be, the more circumspectly we tend to tread, trying to temper the seductive pleasure of a time-dissolving intimacy with our subjects which such texts seem to promise with our historians' sense of their Siren dangers. Nevertheless, in the case of the still largely unknown story of Philippe de Monte, whose scarce documentary sources, apart from a rich but small handful of private letters, consist of the often enigmatic prefaces to his published music, the addition of two new, very substantial and intensely autobiographical documents can hardly fail to excite expectations of increased access to ‘the man himself’.
Evolution of lavas in the Late Ordovician/Early Silurian Solund‐Stavfjord Ophiolite Complex, West Norway
Authors: Furnes Harald , Hellevang Bjarte , Hellevang Helge , Robins Brian
Published: August 2006

The geochemistry of the volcanic sequence of the Late Ordovician/Early Silurian Solund‐Stavfjord Ophiolite Complex (SSOC) of the Western Norwegian Caledonides has been investigated along 12 stratigraphic sections spaced over a lateral distance of ∼60 km. The metabasalts commonly show a cyclic organization, comprising sheet flows followed by pillow lavas and with volcanic breccias at the top of some volcanic units. The proportions of the volcanic rock types vary considerably along‐axis, even within short distances. The robust nature of the sheeted dike complex, the proportion and regional distribution of the various volcanic rocks, the aphyric nature of the metabasalts, as well as the predominance of Fe‐Ti basalts suggest that the SSOC formed at an intermediate to fast spreading ridge, probably within a back‐arc basin. The variations in the concentrations of the incompatible (e.g., Zr) and compatible (e.g., Cr) elements in the lavas are substantial, i.e., from 49–384 ppm and 66–443 ppm, respectively. Nd isotopic ratios show only minor variations, suggesting that the lavas were generated from an isotopically uniform source. The variations in the incompatible elements (represented by Zr) define stratigraphic units ∼25 to 150 m thick, with either gradual decreases or increases in Zr concentrations, while Cr may show different trends. The different Zr‐Cr covariations are interpreted in the light of a numerical model in which fractional crystallization and mixing of various magmas are the principal processes. Through upwardly Zr‐increasing units, Cr generally decreases and estimated magma densities increase, compatible with progressive fractional crystallization. However, through upwardly Zr‐decreasing units, Cr and estimated magma densities either increase or decrease, trends that are attributed to hybridization in frequently replenished magma chambers. Within short lateral distances (<1 km), the geochemical stratigraphy changes dramatically, excluding eruption from a homogeneous, axially continuous magma chamber. Instead, we propose that the volcanic sequence was fed from small, separate magma lenses that evolved independently of each other.
Interpreting ancient ice in a shallow ice core from the South Yamato (Antarctica) blue ice area using flow modeling and compositional matching to deep ice cores
Authors: Moore John C. , Nishio Fumihiko , Fujita Shuji , Narita Hideki , Pasteur Elizabeth , Grinsted Aslak , Sinisalo Anna , Maeno Norikazu
Published: August 2006

We explore methods of dating a 101 m ice core from a bare ice ablation area in the Yamato Mountains, Dronning Maud Land, East Antarctica. There are two unknowns, the age of the ice at the surface and the age spanned by the core. The ice crystal growth rate was used to estimate the age span of the core at about 5 kyr. CO2, CH4 and N2O data on the core were compared with well‐dated records from deep cores, leading to two plausible matches, both within isotope stage C. Detailed comparison of high‐resolution DEP records from this core and the Dome Fuji core support the 55–61 kyr BP fit best. Oxygen isotope values in the core were then used to constrain the source elevation of the snow in the core, and hence the velocities in a simple flow line model. We inverted the ice core surface age, age span and origin site and their confidence intervals in a sensitivity study of flow model parameter space. The flow line model predicts good matches to the core by reducing glacial flow rates to 70% of present‐day, accumulation rates by 45% with 10% confidence intervals. The modeled surface age for the whole meteorite field yields maximum surface ages of about 90 kyr, which is consistent with known, but poorly constrained, tephra dating, meteorite terrestrial ages and the frequency of meteorite discoveries. This approach can be used quite generally to link deep ice cores to surface outcrops on blue ice fields.
Significant light and temperature dependent monoterpene emissions from European beech (Fagus sylvatica L.) and their potential impact on the European volatile organic compound budget
Authors: Dindorf T. , Kuhn U. , Ganzeveld L. , Schebeske G. , Ciccioli P. , Holzke C. , Köble R. , Seufert G. , Kesselmeier J.
Published: August 2006

By using a dynamic branch enclosure system the emission of monoterpenes from European beech (Fagus sylvatica L.) was investigated during two consecutive summer vegetation periods in the years of 2002 and 2003 in Germany. All measurements were performed under field conditions within the framework of the ECHO project (Emission and Chemical Transformation of Biogenic Volatile Organic Compounds, AFO 2000). European beech was characterized as a substantial emitter of monoterpenes, with sabinene being the predominant compound released. The monoterpene emission from European beech was shown to be a function of light and temperature and agreed well to emission algorithms that consider a light and temperature dependent release of volatile organics. Standard emission factors that were measured from these sunlit leaves of European beech ranged up to 4–13 μg g−1 h−1 (normalized to 1000 μmol m−2 s−1, 30°C) in the years of 2003 and 2002, respectively. The nighttime emission of monoterpene compounds was negligible. Also the artificial darkening of the sunlit branch during daylight conditions led to an immediate cessation of monoterpene emission. European beech is the dominating deciduous tree species in Europe. To demonstrate the effect of an updated monoterpene emission factor for European beech in combination with the consideration of a light and temperature dependent monoterpene emission, we applied a species based model simulation on a European scale. With respect to conventional estimates of the European volatile organic compound budget, the latter simulation resulted in relative increases of 16% by taking solely this tree species into account. On local scales these increases exceeded even more than 100% depending on the respective vegetation area coverage of European beech.
Remote sensing of cloud properties using ground‐based measurements of zenith radiance
Authors: Chiu J. Christine , Marshak Alexander , Knyazikhin Yuri , Wiscombe Warren J. , Barker Howard W. , Barnard James C. , Luo Yi
Published: August 2006

We have conducted the first extensive field test of two new methods to retrieve optical properties for overhead clouds that range from patchy to overcast. The methods use measurements of zenith radiance at 673 and 870 nm wavelengths and require the presence of green vegetation in the surrounding area. The test was conducted at the Atmospheric Radiation Measurement Program Oklahoma site during September–November 2004. These methods work because at 673 nm (red) and 870 nm (near infrared (NIR)), clouds have nearly identical optical properties, while vegetated surfaces reflect quite differently. The first method, dubbed REDvsNIR, retrieves not only cloud optical depth τ but also radiative cloud fraction. Because of the 1‐s time resolution of our radiance measurements, we are able for the first time to capture changes in cloud optical properties at the natural timescale of cloud evolution. We compared values of τ retrieved by REDvsNIR to those retrieved from downward shortwave fluxes and from microwave brightness temperatures. The flux method generally underestimates τ relative to the REDvsNIR method. Even for overcast but inhomogeneous clouds, differences between REDvsNIR and the flux method can be as large as 50%. In addition, REDvsNIR agreed to better than 15% with the microwave method for both overcast and broken clouds. The second method, dubbed COUPLED, retrieves τ by combining zenith radiances with fluxes. While extra information from fluxes was expected to improve retrievals, this is not always the case. In general, however, the COUPLED and REDvsNIR methods retrieve τ to within 15% of each other.
Longitudinal hydraulic analysis of river‐aquifer exchanges
Authors: Konrad C. P.
Published: August 2006

A longitudinal analysis of transient flow between a river and an underlying aquifer is developed to calculate flow rates between the river and the aquifer and the location of groundwater seepage into the river as it changes over time. Two flow domains are defined in the analysis: an upstream domain of fluvial recharge, where water flows vertically from the river into the unsaturated portion of the aquifer and horizontally in saturated parts of the aquifer, and a downstream domain of groundwater seepage to the river, where groundwater flows parallel to the underlying impermeable base. The river does not necessarily penetrate completely through the aquifer. A one‐dimensional, unsteady flow equation is derived from mass conservation, Darcy's law, and the geometry of the river‐aquifer system to calculate the water table position and the groundwater seepage rate into the river. Models based on numerical and analytical solutions of the flow equation were applied to a reach of the Methow River in north central Washington. The calibrated models simulated groundwater seepage with a root‐mean‐square error less than 5% of the mean groundwater seepage rates for three low‐flow evaluation periods. The analytical model provides a theoretical basis for a nonlinear exponential base flow recession generated by a draining aquifer, but not an explicit functional form for the recession. Unlike cross‐sectional approaches, the longitudinal approach allows the analysis of the length and location of groundwater seepage to a river, which have important ecological implications in many rivers. In the numerical simulations, the length of the groundwater seepage varied seasonally by about 4 km and the upstream boundary of groundwater seepage was within 689 m of its location at a stream gage on 9 September 2001 and within 91 m of its location on 6 October 2002. To demonstrate its utility in ecological applications, the numerical model was used to calculate differences in length of groundwater seepage to the Methow River under an early runoff scenario and the timing of those differences with respect to life stages of chinook salmon.
How probability weighting affects participation in water markets
Authors: Ranjan Ram , Shogren Jason F.
Published: August 2006

The behavioral tendency to overestimate probabilities of loss can affect a farmer's participation in water markets. We examine this issue with a theoretical model of a nonexpected utility maximizing farmer who places subjective weights on the actual probabilities of loss of water rights due to market transactions. The farmer bargains over sharing of surpluses with the buyer of water. The farmer then incorporates the bargaining outcome in his intertemporal expected benefit maximization problem that accounts for the possible loss of water rights due to its sale out of agriculture. Three key results emerge. First, subjective weighting of probabilities leads to discounting of resources when farmers overestimate probabilities of loss. Second, if farmers have idiosyncratic time preferences, total water supply in the market would depend on the level of heterogeneity in the population. Third, considering the case of two farmers, we find that the farmer with lower endowments bears the burden of risk reduction, whereas the one with higher endowments sells more water for profits. As the level of risk increases, however, the relative difference in risk sharing declines.
Simultaneous lidar and EOS MLS measurements, and modeling, of a rare polar ozone filament event over Mauna Loa Observatory, Hawaii
Authors: Leblanc Thierry , Tripathi Om Prakash , McDermid I. Stuart , Froidevaux Lucien , Livesey N. J. , Read W. G. , Waters J. W.
Published: August 2006

In mid‐March 2005, a rare lower stratospheric polar vortex filamentation event was observed simultaneously by the JPL lidar at Mauna Loa Observatory, Hawaii, and by the EOS MLS instrument onboard the Aura satellite. The event coincided with the beginning of the spring 2005 final warming. On 16 March, the filament was observed by lidar around 0600 UT between 415 K and 455 K, and by MLS six hours earlier. It was seen on both the lidar and MLS profiles as a layer of enhanced ozone, peaking at 1.7 ppmv in a region where the climatological values are usually around or below 1 ppmv. Ozone profiles measured by lidar and MLS were compared to profiles from the Chemical Transport Model MIMOSA‐CHIM. The agreement between lidar, MLS, and the model is excellent considering the difference in the sampling techniques. MLS was also able to identify the filament at another location north of Hawaii.
Large scale dynamics and MJO forcing of ENSO variability
Authors: McPhaden Michael J. , Zhang Xuebin , Hendon Harry H. , Wheeler Matthew C.
Published: August 2006

A simple two‐predictor regression model is developed to estimate the relative influence of large‐scale low frequency ocean‐atmosphere dynamics and high frequency atmospheric forcing on peak sea surface temperature (SST) anomalies associated with El Niño/Southern Oscillation (ENSO) variations for the period 1980–2005. One predictor is equatorial warm water volume (WWV), which is an index for the role that upper ocean heat content plays in regulating ENSO variability. The other predictor characterizes high frequency atmospheric forcing in the western Pacific linked to the Madden‐Julian Oscillation (MJO). The two‐predictor model accounts for about 60–65% of peak Nino3.4 SST anomaly variance at 2–3 season lead times and suggests about equal influence (on average) of low frequency dynamical processes and the MJO on peak ENSO SST anomalies over the past 25 years. The implications of these results for ENSO prediction are discussed.
Seismic attenuation due to wave‐induced flow: Why Q in random structures scales differently
Authors: Müller T. M. , Rothert E.
Published: August 2006

Wave‐induced fluid flow is an important dissipation mechanism of seismic waves in heterogeneous porous solids and several models are reported to quantify the wave attenuation. However, its characteristic frequency dependence in randomly heterogeneous structures remains unclear. For a generic double‐porosity structure the specific attenuation of compressional waves is computed from first principles. It is shown how contrasts in material properties and heterogeneity scales translate into characteristic frequency dependencies of attenuation. The results explain the observed discrepancy of the asymptotic behavior of seismic attenuation in layered porous media with periodic and random disorder.
Effects of sea level change on the upstream Kuroshio Current through the Okinawa Trough
Authors: Kao Shuh Ji , Wu Chau‐Ron , Hsin Yi‐Chia , Dai Minhan
Published: August 2006

Sea‐level effects on the Kuroshio Current (KC) in the Okinawa Trough (OT) are examined using a 3‐D ocean model. When the sea level is −135 m (for the Last Glacial Maximum), topographic high at the southernmost OT partially blocks the KC throughflow, resulting in a 43% reduction of KC inflow. Meanwhile, meandering is enhanced and deepwater ventilation is reduced. However, the KC does not migrate to the east off the OT as suggested previously. When sea level is −40 m (for the beginning of Holocene), the modeled flow pattern resembled present KC in terms of flow path and volume transport. Sea level fluctuation may act as a major control altering the KC course in the OT, leading to significant changes in horizontal and vertical water exchange. It may alter surface water properties, biogeochemistry in both water column and sediments below, potentially, downstream KC and climate over the northeast Asia.
Factors controlling temporal and spatial variations of atmospheric deposition of 7Be and 210Pb in northern Taiwan
Authors: Huh Chih‐An , Su Chih‐Chieh , Shiau Liang‐Jian
Published: August 2006

Fluxes of 7Be and 210Pb monitored at two contrasting sites in northern Taiwan were studied along with meteorological data to elucidate factors controlling their temporal and spatial variations. The 9 year time series of both nuclides at Nankang in the Taipei Basin show dependence on wet precipitation and follow an annual cycle regulated by typhoons, monsoons, and mei‐yü. Superimposed on the annual cycle are interannual variation caused by El Niño–Southern Oscillation and intraseasonal oscillations due to the passage or invasion of fronts, cold surges, dust storms, and the Pacific high‐pressure system. The observed 7Be/210Pb ratios are indicative of the source regions of the fallout nuclides, with higher ratios from high‐altitude rain and lower ratios from dry fallout and low‐altitude rain. The 2 year time series at Yangminshan shows that 7Be and 210Pb fluxes at the mountainous site are in phase with those at Nankang. However, nuclide fluxes at Yangminshan are 4–5 times those at Nankang. After combining results from this and other ancillary studies at Yangminshan, we suggest that (1) in applying fallout nuclides to study the Earth's surface processes, the assumption of constant flux should be made judicially according to the timescales involved, and that (2) the application of fallout nuclides to study soil erosion in hilly areas must consider not only control by wet and dry precipitation but also by direct contact and interaction of clouds with soils enhancing nuclide fluxes.
A study of N-methylacetamide in water clusters: Based on atom-bond electronegativity equalization method fused into molecular mechanics
Authors: Yang Zhong-Zhi , Qian Ping
Published: August 2006

N -methylacetamide (NMA) is a very interesting compound and often serves as a model of the peptide bond. The interaction between NMA and water provides a convenient prototype for the solvation of the peptides in aqueous solutions. Here we present NMA-water potential model based on atom-bond electronegativity equalization method fused into molecular mechanics (ABEEM/MM) that is to take ABEEM charges of all atoms, bonds, and lone-pair electrons of NMA and water molecules into the electrostatic interaction term in molecular mechanics. The model has the following characters: (1)it allows the charges in system to fluctuate responding to the ambient environment; (2) for two major types of intermolecular hydrogen bonds, which are the hydrogen bond forming between the lone-pair electron on amide oxygen and the water hydrogen, and the one forming between the lone-pair electron on water oxygen and the amide hydrogen, we take special treatments in describing the electrostatic interaction by the use of the parameters klpO,H and klpO–,HN–, respectively. The newly constructed potential model based on ABEEM/MM is first applied to amide-water clusters and reproduces gas-phase state properties of NMA(H2O)n (n=1–3) including optimal structures, dipole moments, ABEEM charge distributions, energy difference of the isolated trans- and cis-NMA, interaction energies, hydrogen bonding cooperative effects, and so on, whose results show the good agreement with those measured by available experiments and calculated by ab initio methods. In order to further test the reasonableness of this model and the correctness and transferability of the parameters, many static properties of the larger NMA-water complexes NMA(H2O)n (n=4–6) are also studied including optimal structures and interaction energies. The results also show fair consistency with those of our quantum chemistry calculations.
Cation and anion transport through hydrophilic pores in lipid bilayers
Authors: Kandasamy Senthil K. , Larson Ronald G.
Published: August 2006

To understand the origin of transmembrane potentials, formation of transient pores, and the movement of anions and cations across lipid membranes, we have performed systematic atomistic molecular dynamics simulations of palmitoyl-oleoyl-phosphatidylcholine (POPC) lipids. A double bilayer setup was employed and different transmembrane potentials were generated by varying the anion (Cl−) and cation (Na+) concentrations in the two water compartments. A transmembrane potential of ∼350mV was thereby generated per bilayer for a unit charge imbalance. For transmembrane potential differences of up to ∼1.4V, the bilayers were stable, over the time scale of the simulations (10–50ns). At larger imposed potential differences, one of the two bilayers breaks down through formation of a water pore, leading to both anion and cation translocations through the pore. The anions typically have a short residence time inside the pore, while the cations show a wider range of residence times depending on whether they bind to a lipid molecule or not. Over the time scale of the simulations, we do not observe the discharge of the entire potential difference, nor do we observe pore closing, although we observe that the size of the pore decreases as more ions translocate. We also observed a rare lipid flip-flop, in which a lipid molecule translocated from one bilayer leaflet to the opposite leaflet, assisted by the water pore.
Hexagonal diamond synthesis on h-GaN strained films
Authors: Misra Abha , Tyagi Pawan K. , Yadav Brajesh S. , Rai P. , Misra D. S. , Pancholi Vivek , Samajdar I. D.
Published: August 2006

Chemical vapor deposited diamond films grown on strained gallium nitride-coated quartz substrate are found to display a dominantly hexagonal diamond phase. The phase identification is done using Raman spectroscopy and orientation imaging microscopy (OIM). The presence of a 1324.4cm−1 band in the Raman spectra is attributed to a hexagonal diamond symmetry, but the unambiguous signature of the hexagonal phase is confirmed by OIM. A phase map of the sample clearly shows that 88% of the scanned sample area is hexagonal diamond.
Multidimensional reactive scattering with quantum trajectories: Dynamics with Morse vibrational modes
Authors: Babyuk Dmytro , Wyatt Robert E.
Published: August 2006

The reactive scattering of a wave packet is studied by the quantum trajectory method for a model system with up to 25 Morse vibrational modes. The equations of motion are formulated in curvilinear reaction path coordinates with the restriction to a planar reaction path. Spatial derivatives are evaluated by the least squares method using contracted basis sets. Dynamical results, including trajectory evolution and time-dependent reaction probabilities, are presented and analyzed. For the case of one Morse vibrational mode, the results are in good agreement with those derived through direct numerical integration of the time-dependent Schrödinger equation.
Effect of incorporating nonlanthanoidal indium on the ferroelectric performance of Bi4Ti3O12 thin films
Authors: Chang Y. C. , Kuo D. H.
Published: August 2006

Nonlanthanoid-substituted In-x-Bi4Ti3O12 films with different indium contents at x=0, 0.2, 0.4, and 0.5, based upon the chemical formula of (Bi4−xInx)Ti3O12, were prepared at 600°C by chemical solution deposition. In-0.4-Bi4Ti3O12 films displayed a large remanent polarization of 57μC∕cm2, coercive field of 100KV∕cm, high nonvolatile polarization ⩾30μC∕cm2 after 1010 switching cycles, and low annealing temperature of 600°C. Good ferroelectric properties are mainly attributed to the partial substitution of the smaller-sized Ti4+ site by the larger-sized In3+ to enhance electrical polarization by a dimensional change of unit cell and to provide fatigue resistance by lattice distortion and chemical stabilization.
Rubbing-induced anisotropy of long alkyl side chains at polyimide surfaces
Authors: Jayathilake Himali D. , Zhu Min Hua , Rosenblatt Charles , Bordenyuk Andrey N. , Weeraman Champika , Benderskii Alexander V.
Published: August 2006

Molecular organization at polyimide surfaces used as alignment layers in liquid crystal displays was investigated using vibrational sum frequency generation (SFG) spectroscopy. We focus on the orientation of the long alkyl side groups at the polymer surface using polarization-selected SFG spectra of the CH3- and CH2-stretch modes of the side chain. Mechanical rubbing and baking, an accepted industrial procedure used to produce pretilt of the liquid crystal, was found to induce pronounced azimuthal anisotropy in the orientational distribution of the alkyl side chains. Orientational analysis of the SFG vibrational spectra in terms of the azimuthal and tilt angles (in and out of plane, respectively) of the alkyl side chains shows their preferential tilt along the rubbing direction, with the azimuthal distribution narrower for stronger rubbed polymer samples.
Dynamics of relaxation of entangled polymers in shear flow
Authors: Bruzzone Samantha , Malvaldi Marco
Published: August 2006

The application of shear flow to entangled polymer melts can strongly modify its rheological and physicochemical behaviors, giving rise to an acceleration of several chemical processes such as diffusion-controlled reactions. In the present work, we investigate the modification of conformational and diffusive properties of an entangled polymer in shear flow by numerical methods. The flow affects both the conformational and diffusive properties of the system, giving rise to a quasinematic ordering of the macromolecules which take prolate spheroid shape with the main axis aligned to the shear direction. The shear flow is found to accelerate the overall diffusion of the chains in all directions at times longer than the polymer relaxation time. The polymer chains display a quite peculiar displacement behavior in direction parallel to the flow. At the same conditions, the linear relation between the diffusion constant in direction perpendicular to the flow and the inverse of the relaxation time, usually adopted in equilibrium regimes, is shown to hold even in the presence of flow.
Importance of short-range versus long-range Hartree-Fock exchange for the performance of hybrid density functionals
Authors: Vydrov Oleg A. , Heyd Jochen , Krukau Aliaksandr V. , Scuseria Gustavo E.
Published: August 2006

We consider a general class of hybrid density functionals with decomposition of the exchange component into short-range and long-range parts. The admixture of Hartree-Fock (HF) exchange is controlled by three parameters: short-range mixing, long-range mixing, and range separation. We study how the variation of these parameters affects the accuracy of hybrid functionals for thermochemistry and kinetics. For the density functional component of the hybrids, we test three nonempirical approximations: local spin-density approximation, generalized gradient approximation (GGA), and meta-GGA. We find a great degree of flexibility in choosing the mixing parameters in range-separated hybrids. For the studied properties, short-range and long-range HF exchange seem to have a similar effect on the errors. One may choose to treat the long-range portion of the exchange by HF to recover the correct asymptotic behavior of the exchange potential and improve the description of density tail regions. If this asymptote is not important, as in solids, one may use screened hybrids, where long-range HF exchange is excluded. Screened hybrids retain most of the benefits of global hybrids but significantly reduce the computational cost in extended systems.
Structural and electronic properties of Sin, Sin−, and PSin−1 clusters (2⩽n⩽13): Theoretical investigation based on ab initio molecular orbital theory
Authors: Nigam Sandeep , Majumder Chiranjib , Kulshreshtha S. K.
Published: August 2006

The geometric and electronic structures of Sin, Sin−, and PSin−1 clusters (2⩽n⩽13) have been investigated using the ab initio molecular orbital theory formalism. The hybrid exchange-correlation energy functional (B3LYP) and a standard split-valence basis set with polarization functions (6-31+G(d)) were employed to optimize geometrical configurations. The total energies of the lowest energy isomers thus obtained were recalculated at the MP2/aug-cc-pVTZ level of theory. Unlike positively charged clusters, which showed similar structural behavior as that of neutral clusters [Nigam et al., J. Chem. Phys. 121, 7756 (2004)], significant geometrical changes were observed between Sin and Sin− clusters for n=6, 8, 11, and 13. However, the geometries of P substituted silicon clusters show similar growth as that of negatively charged Sin clusters with small local distortions. The relative stability as a function of cluster size has been verified based on their binding energies, second difference in energy (ΔE2), and fragmentation behavior. In general, the average binding energy of Sin− clusters is found to be higher than that of Sin clusters. For isoelectronic PSin−1 clusters, it is found that although for small clusters (n<4) substitution of P atom improves the binding energy of Sin clusters, for larger clusters (n≥4) the effect is opposite. The fragmentation behavior of these clusters reveals that while small clusters prefer to evaporate monomer, the larger ones dissociate into two stable clusters of smaller size. The adiabatic electron affinities of Sin clusters and vertical detachment energies of Sin− clusters were calculated and compared with available experimental results. Finally, a good agreement between experimental and our theoretical results suggests good prediction of the lowest energy isomeric structures for all clusters calculated in the present study.
Measurement of conduction band deformation potential constants using gate direct tunneling current in n-type metal oxide semiconductor field effect transistors under mechanical stress
Authors: Lim Ji-Song , Yang Xiaodong , Nishida Toshikazu , Thompson Scott E.
Published: August 2006

An experimental method to determine both the hydrostatic and shear deformation potential constants is introduced. The technique is based on the change in the gate tunneling currents of Si-metal oxide semiconductor field effect transistors (MOSFETs) under externally applied mechanical stress and has been applied to industrial n-type MOSFETs. The conduction band hydrostatic and shear deformation potential constants (Ξd and Ξu) are extracted to be 1.0±0.1 and 9.6±1.0eV, respectively, which is consistent with recent theoretical works.
Extensions of r12 corrections to CC2-R12 for excited states
Authors: Neiss Christian , Hättig Christof , Klopper Wim
Published: August 2006

As known since about two decades, R12 methods, which include terms linear in the interelectronic distance r12 in the wave function, improve substantially the basis set convergence of the ground state correlation energy. In a previous study, however, it was found that the same approach does not give a similar systematic improvement if applied to excited states in the framework of coupled cluster response theory. In the present work, we examine the reason for this behavior and show that the inclusion of additional orbitals in the construction of the r12 pair functions leads to an enhanced basis set convergence (and thus a balanced description) also for the excited states.
Low compressible noble metal carbides with rocksalt structure: Ab initio total energy calculations of the elastic stability
Authors: Fan Chang-Zeng , Zeng Song-Yan , Zhan Zai-Ji , Liu Ri-Ping , Wang Wen-Kui , Zhang Ping , Yao Yu-Gui
Published: August 2006

The authors have systematically studied the mechanical stability of all noble metal carbides with a rocksalt structure by calculating their elastic constants within the density function theory scheme. It was found that only four carbides (RuC, PdC, AgC, and PtC) are mechanically stable. In particular, the authors have shown that RuC, PdC, and PtC have very high bulk modulus, which has been remarkably observed by the most recent experiment for the case of PtC. From the calculated density of states, it can be concluded that these compounds are metallic, like the conventional group IV and group V transition metal carbides.
Time-resolved photoluminescence studies of carrier diffusion in GaN
Authors: Olaizola S. M. , Fan W. H. , Hashemizadeh S. A. , Wells J.-P. R. , Mowbray D. J. , Skolnick M. S. , Fox A. M. , Parbrook P. J.
Published: August 2006

The authors have studied the diffusion of carriers in GaN by photoluminescence and pump-probe spectroscopy in an InGaN∕GaN single quantum well sample at 300K. The sample was designed with the quantum well buried beneath a thick (240nm) GaN layer. When pumping above the GaN band gap, the carriers that are excited in the GaN layer diffuse to the InGaN quantum well before recombining radiatively. The hole diffusion coefficient was determined from the rise time of the quantum well photoluminescence, together with pump-probe experiments. A value of 2.0±0.4cm2∕s is found for the diffusion coefficient.
Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon
Authors: Espinosa H. D. , Peng B. , Moldovan N. , Friedmann T. A. , Xiao X. , Mancini D. C. , Auciello O. , Carlisle J. , Zorman C. A. , Merhegany M.
Published: August 2006

In this work, the authors report the mechanical properties of three emerging materials in thin film form: single crystal silicon carbide (3C-SiC), ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon. The materials are being employed in micro- and nanoelectromechanical systems. Several reports addressed some of the mechanical properties of these materials but they are based in different experimental approaches. Here, they use a single testing method, the membrane deflection experiment, to compare these materials’ Young’s moduli, characteristic strengths, fracture toughnesses, and theoretical strengths. Furthermore, they analyze the applicability of Weibull theory [Proc. Royal Swedish Inst. Eng. Res. 153, 1 (1939); ASME J. Appl. Mech. 18, 293 (1951)] in the prediction of these materials’ failure and document the volume- or surface-initiated failure modes by fractographic analysis. The findings are of particular relevance to the selection of micro- and nanoelectromechanical systems materials for various applications of interest.