bluuebunny/crossref_metadata_2025 huggingface dataset:
The design of polymers for contact lens applications
Authors: Tighe Brian J.
Published: March 2007

The use of thermoplastics, elastomers and hydrogel polymers in contact lens applications is discussed in terms of the balance of properties required for the lens to function in a satisfactory manner. Although there are several thermoplastics that would appear to offer advantages over poly(methyl methacrylate), the most widely used polymer, the inherent disadvantages are in each case too great. The clarity, toughness, physiological inactivity and ease of fabrication are shared by many polymers, but its critical surface tension governing as it does the maintenance of a coherent tear film on the lens surface is unique amongst materials that are otherwise acceptable.

The development of hydrogel polymers is discussed in terms of the potential use of this group of polymers in lenses designed for continuous as distinct from daily wear. The specific requirements of such a lens are considered in the light of the properties possessed by the cornea. Apart from the optical properties of thin (∼0.2 mm) sections of material, the most important parameters are oxygen permeability (since the cornea is avascular a relatively high permeability is required), mechanical properties (the material must be soft enough to avoid discomfort but rigid enough to resist deformation during eyelid movement) and surface hydrophilicity (most conveniently described in terms of the critical surface tension phenomena).
Characterization of interfacial solvent in protein complexes and contribution of wet spots to the interface description
Authors: Teyra Joan , Pisabarro M. T.
Published: March 2007

Water networks in protein interfaces can complement direct interactions contributing significantly to molecular recognition, function, and stability of protein association. Thus, water can be seen as an extension or addition of protein structural features, which may add plenty of information to protein interfacial definition. However, solvent is frequently neglected in protein interaction studies. Analysis of the interfacial information contained in the PDB is essential to achieve more accurate descriptions of protein interfaces. With this aim, we have used the SCOWLP database (http://www.scowlp.org) and applied computational geometry methods to extract and analyze interfacial information of a high‐resolution nonredundant dataset of 176 protein complexes containing obligate and transient interfaces. We have identified all interfacial residues and characterized them in terms of temperature factors, secondary structure, residue composition, and pairing preferences to understand their contribution to the interface description. We have paid special attention to water‐bridged residues; focusing on those that interact only mediated by a water molecule called wet spots. Our results show that 40.1% of the interfacial residues are interacting through water and that wet spots represent a 14.5% of the total, emphasizing the importance of the inclusion of solvent in protein interaction studies, and the contribution of wet spots to interfacial description. Wet spots present similar characteristics to residues binding buried water molecules in the core or cavities of proteins; being preferably located in nonregular secondary structures and establishing hydrogen bonds by their main‐chains. We observe that obligate and transient interfaces present a comparable amount of solvent. Moreover, the role of solvent in both complex types differs according to the different nature of their interfaces. The information obtained in our studies will assist in the process of accomplishing more accurate descriptions of protein interfaces and may be helpful to improve comparison of protein family interfaces, to facilitate rational ligand design, and to guide protein docking. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Real‐SPINE: An integrated system of neural networks for real‐value prediction of protein structural properties
Authors: Dor Ofer , Zhou Yaoqi
Published: March 2007

Proteins can move freely in three‐dimensional space. As a result, their structural properties, such as solvent accessible surface area, backbone dihedral angles, and atomic distances, are continuous variables. However, these properties are often arbitrarily divided into a few classes to facilitate prediction by statistical learning techniques. In this work, we establish an integrated system of neural networks (called Real‐SPINE) for real‐value prediction and apply the method to predict residue‐solvent accessibility and backbone ψ dihedral angles of proteins based on information derived from sequences only. Real‐SPINE is trained with a large data set of 2640 protein chains, sequence profiles generated from multiple sequence alignment, representative amino‐acid properties, a slow learning rate, overfitting protection, and predicted secondary structures. The method optimizes more than 200,000 weights and yields a 10‐fold cross‐validated Pearson's correlation coefficient (PCC) of 0.74 between predicted and actual solvent accessible surface areas and 0.62 between predicted and actual ψ angles. In particular, 90% of 2640 proteins have a PCC value greater than 0.6 between predicted and actual solvent‐accessible surface areas. The results of Real‐SPINE can be compared with the best reported correlation coefficients of 0.64–0.67 for solvent‐accessible surface areas and 0.47 for ψ angles. The real‐SPINE server, executable programs, and datasets are freely available on http://sparks.informatics.iupui.edu. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Creating Ultrathin Nanoscopic Collagen Matrices For Biological And Biotechnological Applications
Authors: Cisneros David A. , Friedrichs Jens , Taubenberger Anna , Franz Clemens M. , Muller Daniel J.
Published: March 2007

The biofunctionalization of materials creates interfaces on which proteins, cells, or tissues can fulfill native or desired tasks. Here we report how to control the assembly of type I collagen into well‐defined nanoscopic matrices of different patterns. Collagen fibrils in these ultrathin (≈3 nm) matrices maintained their native structure as observed in vivo. This opens up the possibility to create programmable biofunctionalized matrices using collagen‐binding proteins or proteins fused with collagen‐binding domains. Applied to eukaryotic cells, these nanostructured matrices can direct cellular processes such as adhesion, orientation and migration.
Directional Alignment of MG63 Cells on Polymer Surfaces Containing Point Microstructures
Authors: Mills Christopher A. , Fernandez Javier G. , Martinez Elena , Funes Miriam , Engel Elisabeth , Errachid Abdelhamid , Planell Josep , Samitier Josep
Published: March 2007

MG63 cells cultured on regular arrays of point microstructures (posts and holes) are shown to preferentially align at certain angles to the pattern of the structures, at 0°, 30°, and 45° in particular. The effect is found to be more pronounced for post rather than hole structures (although no significant difference is found for the angles the cells make to the holes or posts) and is thought to be due to the fact that the cells use the posts as anchorage points to hold themselves to the surface. It is also shown that cells preferentially align with the structures depending on the dimensions of the structures and the distance between neighboring structures. This is important when designing structured surfaces for cell–surface interaction studies for materials to be used in, for example, drug delivery or tissue engineering.
Performance of a MANET directional MAC protocol with angle‐of‐arrival estimation
Authors: Liu Kun , Hamouda Walaa , Youssef Amr
Published: March 2007

The use of directional antennas in mobile ad hoc networks (MANETs) has shown to offer large throughput gains relative to omnidirectional antennas. When used in ad hoc networks, directional medium‐access‐control (DMAC) protocols usually require all nodes, or part of nodes, to be aware of their exact locations. This location information is typically provided using a global positioning system (GPS). Although GPS systems are designed to be as nearly accurate as possible, there are still estimation errors that can cause a relatively large deviation from the actual GPS receiver position. In this paper, we investigate the effect of inaccurate node position estimation on the throughput of these protocols. Our results clearly indicate that the advantages of DMAC protocols diminish if the available position information is not accurate enough. As an alternative, we propose an efficient DMAC protocol that utilizes signal parameter estimation via the rotational invariance technique (ESPRIT) for direction‐of‐arrival (DOA) estimation; alleviating the need for GPS and, hence, avoiding the degrading associated with typical GPS position estimation errors. Moreover, unlike GPS‐based protocols, our protocol is suitable for both outdoor and indoor applications. Under different operating conditions and channel models, our simulation results show the throughput improvement achieved using the proposed protocol relative to the IEEE 802.11. Copyright © 2007 John Wiley & Sons, Ltd.
Effects of deodorization on the stability of vegetable oils
Authors: Baldwin A. Richard
Published: March 2007

Corn oil, soybean oil, and grain sorghum oil have been deodorized in a laboratory unit equipped with a take‐off for removal of samples at various times during deodorization. Stabilities of the oils increase rapidly during the initial part of the deodorization and this increase is caused apparently by heat destruction of pro‐oxidants such as peroxides rather than by removal of volatile materials through steam distillation. These laboratory results were confirmed by a similar study of commercial deodorization of alkali‐refined and winterized corn oil.
The transesterification and chromatographic treatment of fish liver oils as a means of concentrating vitamin A
Authors: Karnovsky M. L. , Rapson W. S. , Van Rensburg N. J.
Published: March 2007

Fish liver oils containing vitamin A esters have been catalytically transesterified with ethyl alcohol, and the proportions of vitamin A alcohol produced under various conditions have been evaluated chromatographically.
The oxidation of methyl oleate. II. A reaction between methyl hydroperoxido oleate and oleic acid
Authors: Swift C. E. , Dollear F. G.
Published: March 2007

Oleic acid is intermolecularly oxidized by methyl hydroperoxido leate at 90°C, through the addition of oxygen at the olefinic bond with the formation of opexy and dihydroxy compounds. Only the lowmelting isomeric form of dihydroxystearic acid could be isolated from the reaction mixture. The oxidation of olefinic linkages by hydroperoxides appears to account, at least in part, for the observed reduction of unsaturation in autoxidizing fats.
A technique for testing the reversion properties of hydrogenated soybean oil shortenings
Authors: Handschumaker E.
Published: March 2007

A technique has been described which was found to yield specific and reproducible evaluations of the reversion properties of shortening samples containing hydrogenated soybean oil. It was shown to be advantagenous to conduct the test by smelling rather than by tasting. The use of a control rendered the test specific and by expanding to a series of controls of varying concentrations, it was found possible to increase the discrimination of the test. The statistical method reported by Dr. Bliss (3) was used to analyze the data obtained.
The flavor problem of soybean oil. III. A four‐sample, glass laboratory deodorizer
Authors: Schwab Arthur W. , Dutton Herbert J.
Published: March 2007

A glass laboratory deodorizer has been described which permits the simultaneous deodorization of four samples under nearly identical conditions of time, temperature, pressure and rate of steam flow. The design includes provision for measuring and controlling the steam flow, for preventing bumping, for “breaking” the vacuum, and for heating and cooling the deodorizer. Successful deodorizations have been made in relatively short periods of time. Upon deodorization of the same alkali‐refined bleached oil in each of the four flasks no difference has been found either in the initial quality or in the stability of the samples.
Pilot‐plant manufacture of peanut protein
Authors: Arthur Jett C. , Crovetto A. J. , Molaison L. J. , Guilbeau W. F. , Altschul A. M.
Published: March 2007

Pilot‐plant production of peanut protein from solvent‐extracted meal was investigated with respect to the effect of temperature of extract liquor during precipitation and the rate of addition of sulfur dioxide on the settling rate of the precipitated protein. As the rate of addition of sulfur dioxide was increased, and the temperature of the extract liquor was decreased the density and the settling rate of the protein curd increased. Spray washing of the extracted meal was more efficient than the previously reported dilution method of washing and resulted in a greater yield of protein.
Micro‐methods in lipide chemistry
Authors: Kretchmer Norman
Published: March 2007

When dealing with biological tissues, it has become more and more necessary to deal with small samples. The field of lipide analysis on a micro level has been reviewed and an example has been given of how a small sample of lipide can be analyzed for its component parts.
The identification of the fatty acids of the fat from a North American black bear
Authors: Sell Harold M. , Taylor Betty M. , Miller Elroy J.
Published: March 2007

A study has been made of the identification of the fatty acids of the fat from a North American black bear. The methyl esters of the fatty acids from the fat were prepared and fractionated through a Stedman Column. Myristie, palmitic, stearic, oleic, palmitoleic, and linoleic acids were identified by the melting points of the p‐bromophenacyl ester of the saturated acids and the hydroxy and bromine addition compounds of the unsaturated acids.
Semi‐micro analysis of soap. I. Semi‐micro determination of the usual constituents
Authors: Blank E. W.
Published: March 2007

A procedure for the complete semi‐micro analysis of soap has been developed. Semi‐micro methods are valuable in research work and in legal cases where limited quantities of sample are available. In general, the analytical results obtained on a semi‐micro basis and on a macro basis are comparable. Very little special apparatus is required for the semi‐micro analysis of a soap, and most of the procedures employed present analogies with the usual methods of soap analysis.
Isomerization of drying and semi‐drying oils: The use of anthraquinone as a conjugation catalyst
Authors: Falkenburg L. B. , DeJong WM. , Handke D. P. , Radlove S. B.
Published: March 2007

Anthraquinone and its derivatives have been found to be effective catalysts for the isomerization of drying and semi‐drying oils to conjugated forms. A possible mechanism to account for the catalytic activity of these materials has been proposed. Possible commerical application of the isomerization of oils with anthraquinone was briefly discussed.
Bromination of methyl esters of soybean fat acids and methyl linoleate with N‐bromosuccinimide
Authors: Teeter Howard M.
Published: March 2007

The reaction of N‐bromosuccinimide with methyl esters of soybean fat acids and with methyl linoleate has been investigated, and the influence of changes in the conditions of reaction has been studied.

The reaction of brominated methyl esters of soybean fat acids with sodium methoxide produced both methoxylated products and a dimer‐like substance.

The reaction of brominated methyl esters of soybean fat acids with sodium cyanide and cuprous cyanide did not result in significant replacement of bromine with the cyano group.
Autoxidation of fats. II. Preparation and oxidation of methyl oleate‐maleic anhydride adduct
Authors: Bickford W. G. , Fisher G. S. , Kyame Lillian , Swift C. E.
Published: March 2007

The adduct of maleic anhydride and methyl oleate has been prepared and characterized. The physical and chemical properties of the adduct indicate that it is composed of one mole of each of the reactants and that the double bond of methyl oleate has not been saturated. Oxidative fission of the adduct showed that the adduct consisted of a mixture of four isomers which yielded octanoic, nonanoic, suberic, and azelaic acids on ozonolysis. Isolation of these four acids from the fission products indicates that the addition reaction probably proceeds by a mechanism analogous to that proposed by Farmer, Koch, and Sutton for autoxidation. In view of the similarity between the reactions of maleic anhydride and oxygen with unsaturated compounds, the foregoing observations appear to support the free radical chain mechanism for the autoxidation of fats.
Using system differences to orchestrate change: a systems‐guides intervention model
Authors: O'Connor Patricia A.
Published: March 2007

Successful community‐based interventions require that change agents give attention to the complexities of interwoven systems, described in the literature as complicated or complex, purposeful or purposive. The author further notes the separate standards, norms, principles and/or goals (here‐named systems‐guides) of systems. This paper describes the author's experience as a consultant to a multi‐system collaboration where observed tensions among participants resulted in the author's implementation of a three‐step systems‐guides model, which can increase change agents' effectiveness with systems. The steps comprise: detection (of systems, systems‐guides, and discrepancies between them; here through observation); documentation (of discrepancies; here through small group discussions); dissemination (to systems participants; here to the collaboration). Two small but fundamental systems changes emerged from systems participants, not from the change agent/author who facilitated systems members' recognition of discrepancies. A major limitation in the implementation of this systems‐guides model centers on the critical necessity of the close relationship change agents must have with the involved systems.
Influence of iodine on nutritional, metabolic and immunological response of goats fed Leucaena leucocephala leaf meal diet
Authors: PATTANAIK A. K. , KHAN S. A. , GOSWAMI T. K.
Published: March 2007

Fifteen indigenous nondescript kids (8·2 kg; 8 months initial age), randomly allotted into three equal groups, were used to study the effects of supplementation of extra iodine on their performance when fed a leucaena (Leucaena leucocephala) leaf meal containing diet. Group I (CON) was fed a control concentrate supplement consisting of a conventional protein source whereas the other two groups (LL and LLI) were fed a concentrate containing leucaena leaf meal so as to supply 0·5 of the net crude protein (CP) requirements. Additionally, animals in group LLI were given supplemental iodine (as potassium iodide solution) at 0·25 mg/head/day. Wheat straw was provided ad libitum as the sole source of roughage during the 120 days of the experimental period. A metabolism trial, conducted at the end of the feeding trial, revealed no variation in the dry matter intake (DMI) among the groups. A significant (P<0·01) decline was evident in digestibility of CP in both the leucaena-fed groups (0·463 and 0·482 versus 0·586) whilst that of the other organic components remained unaffected. Animals on the LL diet exhibited lower (P<0·01) nitrogen retention and average daily gain (ADG) in live weight (LW). Blood collected periodically was analysed for the thyroid hormones triiodothyronine (T3) and thyroxine (T4) as well as other biochemical parameters. At the end of the experimental feeding, the cell-mediated immune (CMI) response of the goats was assessed by intra-dermal inoculation of phytohaemagglutinin-P and measuring the change in skin thickness at various post-inoculation hours. The results revealed that the serum concentration of glucose was significantly (P<0·05) higher in the LLI group of animals fed leucaena with iodine. The concentration of cholesterol in serum of LL animals increased significantly (P<0·05) compared to the CON and LLI groups. No variation due to dietary interventions was evident in other indices of metabolic profile. While the concentration of circulating T3 remained unaffected due to dietary intervention, that of T4 reduced significantly (P<0·05) in the LL group. Moreover, the T4 concentration in the LLI group remained similar to that of control indicative of positive impact of iodine supplementation. The immune response revealed that the skin thickness of animals in the LL group was lower (P<0·05) as compared to the control, indicating a compromise of CMI response due to feeding of leucaena leaf meal. Supplementation of iodine appeared to be partially effective in potentiating the response. In conclusion, iodine supplementation could be adopted as a strategic management strategy to ameliorate the negative impacts of feeding leucaena leaf meal in growing kids.
Teleseismic tomography of the southern Tyrrhenian subduction zone: New results from seafloor and land recordings
Authors: Montuori Caterina , Cimini Giovanni Battista , Favali Paolo
Published: March 2007

Teleseismic traveltime data, recorded by temporary ocean bottom seismographs deployed in Tyrrhenian Sea around the Aeolian Islands (Tyrrhenian Deep‐sea Experiment (TYDE)), have been used for the first time in Italy to refine the 3‐D model for the deep P wave velocity structure of the southern Tyrrhenian subduction zone. The arrival times of 35 teleseisms have been combined with those recorded by the Italian National Network. In order to obtain a more complete azimuthal coverage of teleseismic rays, 80 events recorded by land stations from 1990 to 2002 have been included in the data set. In total, 2904 P and 314 PKPdf phases, 1300 recorded by ocean bottom instruments, have been collected. The upper mantle structure is reconstructed down to 500 km by a nonlinear inversion of the relative residuals computed with respect to the reference 1‐D velocity model ak135. The obtained tomographic model has a higher resolution than those previously published thanks to the recordings of TYDE seafloor stations. Tomographic results confirm the presence of the Tyrrhenian slab imaged as a high‐velocity body extending from the uppermost mantle down to the bottom velocity model with dip 70–75° NW. The model better defines the geometry of the seismogenic part of the slab. Its lateral extension is about 200 km in the depth interval 150–300 km, where most of the deep seismicity is concentrated. At uppermost mantle depths the fast structure has smaller lateral dimensions (about 100 km). The inversion also points out a wide well‐resolved low‐velocity zone completely surrounding the steeply dipping fast structure from the lower crust down to about 300 km. This feature suggests the presence of a three‐dimensional circulation of asthenospheric flow around the Ionian slab caused by retreat and roll‐back of the slab. Our results are in agreement with recent laboratory experiments, mantle anisotropy studies, geochemical and isotopic analyses, and modeling based on residual topography.
Sediment transport and channel adjustments associated with dam removal: Field observations
Authors: Cheng Fang , Granata Tim
Published: March 2007

This study documents changes in channel geometry, bed level profile, and bed grain size distribution and their relations with the sediment transport at the reach scale, following the removal of a low‐head dam. After the removal, net sediment deposition occurred downstream of the dam, and net erosion occurred in the reservoir, but approximately less than 1% of the sediment stored in the reservoir was transported downstream. No bank erosion was evident either upstream or downstream of the dam. Bed deposition and scouring in the reservoir accounted for a decrease in the bed slope of 30%. The stations downstream of the dam had surface bed material sizes at least 40% finer than preremoval conditions. However, the sediment transport rates downstream of the dam were not significantly different from predam to postdam removal or from an upstream control. Overall, the removal of the dam had only minor effects on the channel adjustment downstream of the dam. A simple analysis linking transport to channel geometry explains this effect.
Stratosphere‐troposphere transport in a numerical simulation of midlatitude convection
Authors: Chagnon Jeffrey M. , Gray Suzanne L.
Published: March 2007

The transport of stratospheric air deep into the troposphere via convection is investigated numerically using the UK Met Office Unified Model. A convective system that formed on 27 June 2004 near southeast England, in the vicinity an upper level potential vorticity anomaly and a lowered tropopause, provides the basis for analysis. Transport is diagnosed using a stratospheric tracer that can either be passed through or withheld from the model's convective parameterization scheme. Three simulations are performed at increasingly finer resolutions, with horizontal grid lengths of 12, 4, and 1 km. In the 12 and 4 km simulations, tracer is transported deeply into the troposphere by the parameterized convection. In the 1 km simulation, for which the convective parameterization is disengaged, deep transport is still accomplished but with a much smaller magnitude. However, the 1 km simulation resolves stirring along the tropopause that does not exist in the coarser simulations. In all three simulations, the concentration of the deeply transported tracer is small, three orders of magnitude less than that of the shallow transport near the tropopause, most likely because of the efficient dilution of parcels in the lower troposphere.
Sensitivity of GPS occultation to the stratopause height
Authors: Schrøder Thomas M. , Ao Chi O. , de la Torre Juárez Manuel
Published: March 2007

We scrutinize temperature profiles collected with radio occultation measurement for an imprint of the stratopause. In the retrieval step that integrates bending angle data to atmospheric refractivity, the falloff toward infinite altitude is constrained in a boundary condition with statistical optimization or extrapolation. We point to the coherence between temperature and density scale height as advocator for a fitting procedure that exploits data down to the stratopause. Data below have higher signal‐to‐noise ratio, but fitting them in costs additional parameters for the shifted sign in scale height gradient. On the basis of noise free simulation using a climatology covering all latitudes, seasons, and hours and on the basis of validation against data collected with weather balloons, laser imaging, and limb sounding, we find that adaptation to the fluctuating stratopause is crucial for the accuracy of the retrieved temperature. To facilitate investigation, the stratopause altitude was preset in the boundary condition according to climatological temperature. Biases between 10 and 50 hPa cancel out when the fitting interval is extended to 7.2 km above the stratopause, almost the average displacement of the maximum density scale height caused by nonlinearity in the temperature profile. This is a reminder that the stratopause should be read from bending angle, not temperature. Moreover, bias would be approaching zero at all levels if the a priori information for extrapolation had been lapse rate, not isothermal conditions. Keeping the model seed for temperature conversion to subsequent retrieval steps eliminates external information from the deconvolved refractivity. It will help argue for radio occultation as independent vehicle for climate monitoring.
Evaluation of the aerosol indirect effect using satellite, tracer transport model, and aircraft data from the International Consortium for Atmospheric Research on Transport and Transformation
Authors: Avey L. , Garrett T. J. , Stohl A.
Published: March 2007

The magnitudes of the “indirect effects” that anthropogenic aerosols have on clouds and climate remain uncertain. Past space‐based characterizations have compared satellite retrievals of cloud properties with satellite‐ or model‐derived aerosol quantities. The two fields have been taken from air masses displaced from each other either horizontally or vertically. Thus, almost by definition, the cloud retrievals have come from different meteorological regimes than the aerosol to which ostensibly they are related. Because cloud properties depend foremost on meteorology, the difference introduces undesired ambiguity in the comparisons. In this study, we compare Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud retrievals with high spatial and temporal resolution output from a tracer transport model (FLEXPART), enabling colocation of fields of pollution and clouds both vertically and horizontally. Anthropogenic carbon monoxide (CO) is used as a passive pollution tracer, because its concentrations are tied to mixing and pollutant source strength, and they are independent of atmospheric oxidation and removal processes on timescales of weeks to months. Cloud and pollution fields are compared along a downwind axis from the U.S. northeastern seaboard for the duration of the summer 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) mission. Where the transport model indicates air as being polluted, cloud re is smaller and cloud optical depth is in some cases higher, at least close to primary source regions. However, within 4 ± 1 days advection time from the northeastern seaboard, cloud perturbations become negligible, probably because of wet‐scavenging of CCN. No conclusive evidence was found for any perturbation to cloud liquid water path by pollution.
Space‐based formaldehyde measurements as constraints on volatile organic compound emissions in east and south Asia and implications for ozone
Authors: Fu Tzung‐May , Jacob Daniel J. , Palmer Paul I. , Chance Kelly , Wang Yuxuan X. , Barletta Barbara , Blake Donald R. , Stanton Jenny C. , Pilling Michael J.
Published: March 2007

We use a continuous 6‐year record (1996–2001) of GOME satellite measurements of formaldehyde (HCHO) columns over east and south Asia to improve regional emission estimates of reactive nonmethane volatile organic compounds (NMVOCs), including isoprene, alkenes, HCHO, and xylenes. Mean monthly HCHO observations are compared to simulated HCHO columns from the GEOS‐Chem chemical transport model using state‐of‐science, “bottom‐up” emission inventories from Streets et al. (2003a) for anthropogenic and biomass burning emissions and Guenther et al. (2006) for biogenic emissions (MEGAN). We find that wintertime GOME observations can diagnose anthropogenic reactive NMVOC emissions from China, leading to an estimate 25% higher than Streets et al. (2003a). We attribute the difference to vehicular emissions. The biomass burning source for east and south Asia is almost 5 times the estimate of Streets et al. (2003a). GOME reveals a large source from agricultural burning in the North China Plain in June missing from current inventories. This source may reflect a recent trend toward in‐field burning of crop residues as the need for biofuels diminishes. Biogenic isoprene emission in east and south Asia derived from GOME is 56 ± 30 Tg yr−1, similar to 52 Tg yr−1 from MEGAN. We find, however, that MEGAN underestimates emissions in China and overestimates emissions in the tropics. The higher Chinese biogenic and biomass burning emissions revealed by GOME have important implications for ozone pollution. We find 5 to 20 ppb seasonal increases in surface ozone in GEOS‐Chem for central and northern China when using GOME‐derived versus bottom‐up emissions. Our methodology can be adapted for other regions of the world to provide top‐down constraints on NMVOC emissions where multiple emission source types overlap in space and time.
Low‐dimensional modeling of hillslope subsurface flow: Relationship between rainfall, recharge, and unsaturated storage dynamics
Authors: Hilberts A. G. J. , Troch P. A. , Paniconi C. , Boll J.
Published: March 2007

We present a coupling between the one‐dimensional Richards equation for vertical unsaturated flow and the one‐dimensional hillslope‐storage Boussinesq equation (HSB) for lateral saturated flow along complex hillslopes. Here the capillary fringe is included in the flow domain as an integral part of the Boussinesq aquifer. The coupling allows quantitative investigation of the role of unsaturated storage in the relationship between rainfall and recharge. The coupled model (HSB coupled) is compared to the original HSB model (HSB original) and a three‐dimensional Richards equation (RE) based model (taken to be the benchmark) on a set of seven synthetic hillslopes, ranging from convergent to divergent. Using HSB original, the water tables are overestimated and the outflow rates are generally underestimated, and there is no delay between rainfall and recharge. The coupled model, however, shows a remarkably good match with the RE model in terms of outflow rates, and the delay between rainfall and recharge is captured well. We also see a clear improvement in the match to the water tables, even though the values are still overestimated for some hillslope shapes, in particular the convergent slopes. We show that for the hillslope configurations and scenarios examined in this paper it is possible to reproduce hydrographs and water table dynamics with a good degree of accuracy using a low‐dimensional hydrological model.
Slow postseismic recovery of geoid depression formed by the 2004 Sumatra‐Andaman Earthquake by mantle water diffusion
Authors: Ogawa Ryoko , Heki Kosuke
Published: March 2007

Earthquakes are accompanied with mass redistributions and cause changes in gravity field and shape of geoid, an equipotential surface coincident with the mean sea surface. Such coseismic changes were detected by satellite gravimetry after the 2004 Sumatra‐Andaman Earthquake, but little has been known on what happens on geoid after the earthquake. Here we report slow postseismic recovery of coseismic geoid depression from satellite measurements. This cannot be explained with simple afterslip or viscous relaxation of Maxwellian upper mantle. It suggests the relaxation of coseismic dilatation and compression by the diffusion of supercritical H2O abundant in the upper mantle. Such a self‐healing system of coseismic geoid undulations, a brand‐new role of water in mantle, would significantly reduce the amount of permanent shifts of the Earth's rotation axis by earthquakes.
An integrated approach based on uniform quantization for the evaluation of complexity of short-term heart period variability: Application to 24h Holter recordings in healthy and heart failure humans
Authors: Porta A. , Faes L. , Masé M. , D’Addio G. , Pinna G. D. , Maestri R. , Montano N. , Furlan R. , Guzzetti S. , Nollo G. , Malliani A.
Published: March 2007

We propose an integrated approach based on uniform quantization over a small number of levels for the evaluation and characterization of complexity of a process. This approach integrates information-domain analysis based on entropy rate, local nonlinear prediction, and pattern classification based on symbolic analysis. Normalized and non-normalized indexes quantifying complexity over short data sequences (∼300 samples) are derived. This approach provides a rule for deciding the optimal length of the patterns that may be worth considering and some suggestions about possible strategies to group patterns into a smaller number of families. The approach is applied to 24h Holter recordings of heart period variability derived from 12 normal (NO) subjects and 13 heart failure (HF) patients. We found that: (i) in NO subjects the normalized indexes suggest a larger complexity during the nighttime than during the daytime; (ii) this difference may be lost if non-normalized indexes are utilized; (iii) the circadian pattern in the normalized indexes is lost in HF patients; (iv) in HF patients the loss of the day-night variation in the normalized indexes is related to a tendency of complexity to increase during the daytime and to decrease during the nighttime; (v) the most likely length L of the most informative patterns ranges from 2 to 4; (vi) in NO subjects classification of patterns with L=3 indicates that stable patterns (i.e., those with no variations) are more present during the daytime, while highly variable patterns (i.e., those with two unlike variations) are more frequent during the nighttime; (vii) during the daytime in HF patients, the percentage of highly variable patterns increases with respect to NO subjects, while during the nighttime, the percentage of patterns with one or two like variations decreases.
Quantification of fetal heart rate regularity using symbolic dynamics
Authors: van Leeuwen P. , Cysarz D. , Lange S. , Geue D. , Groenemeyer D.
Published: March 2007

Fetal heart rate complexity was examined on the basis of RR interval time series obtained in the second and third trimester of pregnancy. In each fetal RR interval time series, short term beat-to-beat heart rate changes were coded in 8bit binary sequences. Redundancies of the 28 different binary patterns were reduced by two different procedures. The complexity of these sequences was quantified using the approximate entropy (ApEn), resulting in discrete ApEn values which were used for classifying the sequences into 17 pattern sets. Also, the sequences were grouped into 20 pattern classes with respect to identity after rotation or inversion of the binary value. There was a specific, nonuniform distribution of the sequences in the pattern sets and this differed from the distribution found in surrogate data. In the course of gestation, the number of sequences increased in seven pattern sets, decreased in four and remained unchanged in six. Sequences that occurred less often over time, both regular and irregular, were characterized by patterns reflecting frequent beat-to-beat reversals in heart rate. They were also predominant in the surrogate data, suggesting that these patterns are associated with stochastic heart beat trains. Sequences that occurred more frequently over time were relatively rare in the surrogate data. Some of these sequences had a high degree of regularity and corresponded to prolonged heart rate accelerations or decelerations which may be associated with directed fetal activity or movement or baroreflex activity. Application of the pattern classes revealed that those sequences with a high degree of irregularity correspond to heart rate patterns resulting from complex physiological activity such as fetal breathing movements. The results suggest that the development of the autonomic nervous system and the emergence of fetal behavioral states lead to increases in not only irregular but also regular heart rate patterns. Using symbolic dynamics to examine the cardiovascular system may thus lead to new insight with respect to fetal development.
Long-term invariant parameters obtained from 24-h Holter recordings: A comparison between different analysis techniques
Authors: Cerutti Sergio , Esposti Federico , Ferrario Manuela , Sassi Roberto , Signorini Maria Gabriella
Published: March 2007

Over the last two decades, a large number of different methods had been used to study the fractal-like behavior of the heart rate variability (HRV). In this paper some of the most used techniques were reviewed. In particular, the focus is set on those methods which characterize the long memory behavior of time series (in particular, periodogram, detrended fluctuation analysis, rescale range analysis, scaled window variance, Higuchi dimension, wavelet-transform modulus maxima, and generalized structure functions). The performances of the different techniques were tested on simulated self-similar noises (fBm and fGn) for values of α, the slope of the spectral density for very small frequency, ranging from −1 to 3 with a 0.05 step. The check was performed using the scaling relationships between the various indices. DFA and periodogram showed the smallest mean square error from the expected values in the range of interest for HRV. Building on the results obtained from these tests, the effective ability of the different methods in discriminating different populations of patients from RR series derived from Holter recordings, was assessed. To this extent, the Noltisalis database was used. It consists of a set of 30, 24-h Holter recordings collected from healthy subjects, patients suffering from congestive heart failure, and heart transplanted patients. All the methods, with the exception at most of rescale range analysis, were almost equivalent in distinguish between the three groups of patients. Finally, the scaling relationships, valid for fBm and fGn, when empirically used on HRV series, also approximately held.
Rotational hysteresis of the exchange anisotropy direction in Co∕FeMn thin films
Authors: Olamit Justin , Liu Kai
Published: March 2007

The effects of rotating an applied field on the exchange anisotropy in Co∕FeMn thin films have been investigated. When the applied field is initially along the cooling field direction, the longitudinal hysteresis loop has a maximum coercivity and the transverse hysteresis loop is flat, indicating that the exchange field is along the cooling field direction. When the applied field angle is rotated away and then restored to the original field cooling direction, the exchange anisotropy direction has changed. The rotation of the exchange field direction trails the applied field and is hysteretic. The rotational hysteresis of the exchange field direction is due to the weak anisotropy in thin FeMn layers and decreases with increasing FeMn thickness.
Capillary pinching in a pinched microchannel
Authors: Amyot O. , Plouraboué F.
Published: March 2007

We report a study of the capillary pinching of a gas bubble by a wetting liquid inside a pinched channel. The capillary pinching induces very reproducible bubbling, at a very well-defined frequency. There are two regimes associated with drip and jet bubbling. In the latter, we show that highly monodispersed bubbles are formed by our pinched channel. The dynamics of the bubble formation also shows two distinct regimes: a long-duration elongation of the air bubble and a rapid relaxation of the interface after interface breakup. The slow regime depends on the flux imposed and the channel geometry. The rapid deformation dynamic regime depends very weakly on the boundary conditions. Scaling arguments are proposed in the context of the lubrication approximation to describe the two regimes.
First-principles investigations of Co- and Fe-doped SnO2
Authors: Wang X. L. , Zeng Z. , Zheng X. H. , Lin H. Q.
Published: March 2007

We have investigated the electronic and magnetic properties of Co- and Fe-doped SnO2 by first-principles methods. The obtained results show that the ferromagnetic order is energetically much favored relative to the antiferromagnetic order in all the considered models of Co- and Fe-doped SnO2. The exchange interaction between Co ions is a long-range ferromagnetic interaction and gradually weakened as the distance between Co ions increases. For Fe-doped SnO2, the exchange interaction is also a long-range ferromagnetic one, but it oscillates with the variation of the distances between Fe ions. In addition, we further probe the concentration effect on the magnetic properties in the doped systems. The obtained results show that the exchange interaction between Co and Fe ions is reduced, implying that the enhancement of Curie temperature is not favored by increasing Co- and Fe-doping concentrations.
Ferromagnetism in sputtered manganese-doped indium tin oxide films with high conductivity and transparency
Authors: Nakamura Toshihiro , Tanabe Kohei , Tsureishi Kazuki , Tachibana Kunihide
Published: March 2007

Mn-doped indium-tin oxide (ITO) films were deposited on glass substrates using radio-frequency magnetron sputtering. The magnetization as a function of magnetic field showed hysteretic behavior at room temperature. According to the temperature dependence of the magnetization, the Curie temperature is higher than 400K. Anomalous Hall effect was observed at low temperatures. Ferromagnetic thin films of Mn-doped ITO exhibited low electrical resistivity of 3.9×10−4Ωcm and high optical transmittance between 75% and 90% in the visible region.
Analytic derivatives for perturbatively corrected “double hybrid” density functionals: Theory, implementation, and applications
Authors: Neese Frank , Schwabe Tobias , Grimme Stefan
Published: March 2007

A recently proposed new family of density functionals [S. Grimme, J. Chem. Phys. 124, 34108 (2006)] adds a fraction of nonlocal correlation as a new ingredient to density functional theory (DFT). This fractional correlation energy is calculated at the level of second-order many-body perturbation theory (PT2) and replaces some of the semilocal DFT correlation of standard hybrid DFT methods. The new “double hybrid” functionals (termed, e.g., B2-PLYP) contain only two empirical parameters that have been adjusted in thermochemical calculations on parts of the G2/3 benchmark set. The methods have provided the lowest errors ever obtained by any DFT method for the full G3 set of molecules. In this work, the applicability of the new functionals is extended to the exploration of potential energy surfaces with analytic gradients. The theory of the analytic gradient largely follows the standard theory of PT2 gradients with some additional subtleties due to the presence of the exchange-correlation terms in the self-consistent field operator. An implementation is reported for closed-shell as well as spin-unrestricted reference determinants. Furthermore, the implementation includes external point charge fields and also accommodates continuum solvation models at the level of the conductor like screening model. The density fitting resolution of the identity (RI) approximation can be applied to the evaluation of the PT2 part with large gains in computational efficiency. For systems with ∼500–600 basis functions the evaluation of the double hybrid gradient is approximately four times more expensive than the calculation of the standard hybrid DFT gradient. Extensive test calculations are provided for main group elements and transition metal containing species. The results reveal that the B2-PLYP functional provides excellent molecular geometries that are superior compared to those from standard DFT and MP2.
Molecular dynamics of homogeneous nucleation in the vapor phase of Lennard-Jones. III. Effect of carrier gas pressure
Authors: Yasuoka Kenji , Zeng X. C.
Published: March 2007

A molecular dynamics simulation of vapor phase nucleation has been performed with 40 000 Lennard-Jones particles for the target gas and 0–160 000 particles for the carrier gas. Three carrier gas models are adopted, including a soft-core model, a Lennard-Jones model, and a modified Lennard-Jones model in which the attractive interaction can be adjusted. The effect of the carrier-gas pressure is assessed through computing and comparing the rate of nucleation and cluster size distribution. It is found that the effect of the carrier-gas pressure can be strongly dependent on the carrier-gas model. A positive effect (enhancement of the nucleation rate) is found with the soft-core potential model, whereas negligible effect is found with the Lennard-Jones potential model. For the modified Lennard-Jones potential with a weak attractive interaction, the carrier-gas effect is positive. However, the effect is negligible with a stronger attractive interaction between the target and carrier-gas particles. A reason for the negligible effect is that the carrier-gas particles are adsorbed on the cluster surface when the density of target and carrier-gas particles are comparable. When the density of carrier-gas particles are four times that of the target particles, the carrier-gas particles tend to mix with the target particles in the clusters.