bluuebunny/crossref_metadata_2025 huggingface dataset:
Smoke inhalation: Diagnosis and treatment
Authors: Clark William R.
Published: August 2005

Smoke inhalation, defined as airway or pulmonary parenchymal injury resulting from the inhalation of toxic combustion products, presents with a wide range of severity in patients with and without skin burns. In patients with severe injuries, the diagnosis is obvious on the basis of the history and clinical presentation; in patients with less severe injuries or those in whom the clinical consequences are delayed, diagnostic precision is difficult because diagnostic clues provide only indirect information. There is no specific treatment so diagnosis is not critical for patient management. Patients at risk include 20% to 30% of flame burn victims who should receive vigorous supportive care. The mortality rate of smoke inhalation victims without a burn is <10%. With a burn the mortality rate is 30% to 50%, suggesting that thermal injury or its treatment is responsible for further lung damage. Endotracheal intubation provides definitive treatment for obstructed or soon‐to‐be obstructed patients. However the diagnosis of smoke inhalationper se is not an indication for airway intubation and respiratory support; 12% of patients without a burn require intubation versus 62% of those with a burn. A translaryngeal tube can be converted to a tracheotomy safely in burn victims; tracheotomies are easier to manage if burns of the neck are excised and grafted prior to placement. Mechanical ventilation with positive end expiratory pressure (PEEP) is the treatment for the pulmonary injury. The early lesions of smoke inhalation often progress in the context of sepsis and other complications of the burn illness to a clinical state consistent with adult respiratory distress syndrome.
Prevention and treatment of postburn scars and contracture
Authors: Robson Martin C. , Barnett Richard A. , Leitch Ian O. W. , Hayward Peter G.
Published: August 2005

The management of postburn reconstruction is complicated by the frequent occurrence of multiple reconstructive needs in a single patient. This article presents a simple, comprehensive approach to burn scar reconstruction. The primary aim of the surgeon is to prevent burn scar deformity by rapid wound closure, correction of tissue deficiencies, and assiduous attention to postoperative splinting and compression therapy. The initial step in managing secondary deformities is to prioritize reconstructive needs. Reconstruction is then carried out in a stepwise fashion aiming to restore active function first, followed by passive function, and finally addressing aesthetic reconstruction. Reconstructive techniques are applied in a hierarchy from simplest to most complex. Primary excision and closure of scars by reorientating the scar to the lines of relaxed skin tension can significantly improve appearance. The use of z‐plasty, flap repair, and tissue expansion are also reviewed. Skin expansion, in particular, has become the standard management of postburn alopecia and, although associated with a relatively high rate of complication, has significantly improved the aesthetic appearance of such patients. The management of common problems affecting the face is discussed with particular reference to management of the eyelids, oral commissure, and lips. These areas need to be reconstructed as aesthetic units and each requires individualized management of donor tissue. The reconstruction of the burn patient is often a long process requiring multiple procedures. The approach presented here advocates a stepwise, prioritized approach aiming at both maximum function as well as optimal appearance.
“Endemic” idiopathic portal hypertension: Report on 32 patients with non‐cirrhotic portal fibrosis
Authors: Vakili Cyrus , Farahvash Mohammad J. , Bynum T. Edward
Published: August 2005

The clinical features, surgical management, and long term follow up of 32 patients from Iran with idiopathic portal hypertension are reported. Many features of the disease are similar to those reported from India and Japan. The unsuspected finding was a 46% history of marked pica of clay (geophagia) in a subset of 26 patients. In addition, 81% of our patients had a prolonged prothrombin time, despite otherwise normal to minimally abnormal liver function tests. Liver biopsies revealed intrahepatic periportal fibrosis with subintimal thickening of terminal branches, and in many specimens a striking peri‐ductular fibrosis was seen in the adjacent bile ducts. The spleen was very large with a dilated artery (external diameter: 11 mm to 15 mm). Portal venous pressure (PVP) was measured intra‐operatively before and after clamping the splenic artery (SA). Clamping the SA consistently caused a decreased in PVP which ranged from 2.0 to 18.2 cm water with the mean ± SEM of 9.7 ± 1.5 cm water (p < 0.001, paired t‐test). It was equivalent to 32.3 ± 3.6% decrease in PVP. Fifteen selected patients (Group I) were managed with splenectomy with excellent short and long term results. The selection criteria for splenectomy included a decrease in PVP to <24 cm of water after clamping the SA. Three patients from this group were re‐examined 10 to 12 years following splenectomy. Cirrhosis had not developed, but the minimal abnormalities in the liver function tests had persisted. Of 17 patients (Group II) requiring a shunting procedure, none of those who survived surgery developed bleeding during the 12 years follow up, however, 2 (12.5%) patients developed encephalopathy.
Impact of Intraoperative Parathyroid Hormone Levels on Surgical Results in Patients with Renal Hyperparathyroidism
Authors: Weber Theresia , Zeier Martin , Hinz Ulf , Schilling Tobias , Büchler Markus W.
Published: August 2005

The aim of our study was to evaluate the impact of intraoperative parathyroid hormone (PTH) measurement on surgical results in patients with renal hyperparathyroidism (HPT). From December 1999 to February 2004, a series of 95 consecutive patients underwent total parathyroidectomy and intraoperative PTH measurement for renal HPT. Intraoperative PTH was measured before and 15 minutes after parathyroidectomy with the Immulite DPC assay for intact PTH. The median PTH levels before surgery were 133.0 pmol/L, which declined to 5.9 pmol/L at the end of the operation. At follow‐up, 91 of 95 (96%) patients presented with normal calcium levels. Persistent renal HPT was seen in three patients, and recurrent HPT was diagnosed in another. In 99% of the patients the intraoperative PTH levels declined more than 50% and in 73% the PTH decay was more than 90%. In 64% of the patients PTH levels dropped into the normal range (< 7.6 pmol/L). Altogether, 97% of the patients with an intraoperative PTH decrease of more than 90% presented with normal PTH levels postoperatively (p = 0.0237), as did all of the patients whose intraoperative PTH dropped into the normal range (p = 0.0432). Intraoperative PTH measurement with a decrease in intraoperative PTH of at least 90% is highly predictive of successful parathyroidectomy and normalization of postoperative calcium and PTH levels.
Coat proteins of two filamentous plant viruses display NTPase activity in vitro
Authors: Rakitina Daria V. , Kantidze Omar L. , Leshchiner Anna D. , Solovyev Andrey G. , Novikov Viktor K. , Morozov Sergey Yu. , Kalinina Natalia O.
Published: August 2005

Coat proteins (CPs) of plant viruses are involved in different stages of the viral life cycle such as virion assembly, replication, movement, vector transmission, and regulation of host defense responses. Here, we report that the CPs of two filamentous RNA viruses, potato virus X (PVX, Potexvirus) and potato virus A (PVA, Potyvirus) exhibit an enzyme activity. The CP isolated from PVX virions possesses ATP‐binding and ATPase activities. Recombinant PVX and PVA CPs produced in Escherichia coli show Mg2+‐dependent ATPase and UTPase activities inhibited by antibodies against virus particles. Deletion of the C‐terminal regions of these proteins diminishes their ATPase activity.
Differential regulation of dual NADPH oxidases/peroxidases, Duox1 and Duox2, by Th1 and Th2 cytokines in respiratory tract epithelium
Authors: Harper Richart W. , Xu Changhong , Eiserich Jason P. , Chen Yin , Kao Cheng-Yuan , Thai Philip , Setiadi Henny , Wu Reen
Published: August 2005

Partially reduced metabolites of molecular oxygen, superoxide () and hydrogen peroxide (H2O2), are detected in respiratory tract lining fluid, and it is assumed that these are key components of innate immunity. Whether these reactive oxygen species (ROS) are produced specifically by the respiratory epithelium in response to infection, or are a non‐specific by‐product of oxidant‐producing inflammatory cells is not well characterized. Increasing evidence supports the hypothesis that the dual function NAD(P)H oxidases/peroxidases, Duox1 and Duox2, are important sources of regulated H2O2 production in respiratory tract epithelium. However, no studies to date have characterized the regulation of Duox gene expression. Accordingly, we examined Duox1 and Duox2 mRNA expression by real‐time PCR in primary respiratory tract epithelial cultures after treatment with multiple cytokines. Herein, we determined that Duox1 expression was increased several‐fold by treatment with the Th2 cytokines IL‐4 and IL‐13, whereas Duox2 expression was highly induced following treatment with the Th1 cytokine IFN‐γ. Duox2 expression was also elevated by polyinosine‐polycytidylic acid (poly(I:C)) and rhinovirus infection. Diphenyleneiodonium (DPI)‐inhibitable apical H2O2 production was similarly increased by the addition of Th1 or Th2 cytokines. These results demonstrate for the first time the regulation of Duox expression by immunomodulatory Th1 and Th2 cytokines, and suggest a mechanism by which ROS production can be regulated in the respiratory tract as part of the host defense response.
An evaluation of mapped species distribution models used for conservation planning
Authors: JOHNSON CHRIS J. , GILLINGHAM MICHAEL P.
Published: August 2005

The widespread use of spatial planning tools in conjunction with increases in the availability of geographic information systems and associated data has led to the rapid growth in the exploration and application of species distribution models. Conservation professionals can choose from a considerable number of modelling techniques, but there has been relatively little evaluation of predictive performance, data requirements, or type of inference of these models. Empirical data for woodland caribou Rangifer tarandus caribou was used to examine four species distribution models, namely a qualitative habitat suitability index and quantitative resource selection function, Mahalanobis distance and ecological niche models. Models for three sets of independent variables were developed and then a temporally independent set of caribou locations evaluated predictive performance. The similarity of species distribution maps among the four modelling approaches was also quantified. All of the quantitative species distribution models were good predictors of the validation data set, but the spatial distribution of mapped habitats differed considerably among models. These results suggest that choice of model and variable set could influence the identification of areas for conservation emphasis. Model choice may be limited by the type of species locations or desired inference. Conservation professionals should choose a model and variable set based on the question, the ecology of the species and the availability of requisite data.
Geometry and kinematics of the Nuncios detachment fold complex: Implications for lithotectonics in northeastern Mexico
Authors: Higuera‐Díaz I. Camilo , Fischer Mark P. , Wilkerson M. Scott
Published: August 2005

Using recent geologic mapping combined with digital elevation data, aerial photo interpretation, and cross section balancing, we describe the three‐dimensional (3‐D) geometry and kinematics of the Nuncios Fold Complex in the Monterrey Salient of northeastern Mexico. This map‐scale, evaporite‐cored detachment fold structure involves Upper Jurassic through Cretaceous rocks deformed during the Laramide orogeny and comprises two westward plunging anticlines and an intervening, eastward plunging syncline. Seven balanced cross sections and a 3‐D model of this north vergent structure document substantial along‐strike variations in both fold geometry and detachment depth, suggesting that 3‐D flow of the detachment layer may have occurred during folding. Comparison of folds in the Monterrey Salient with those in the neighboring Parras Basin suggests that the latter south vergent folds root to a shallower detachment. We suggest that northward transport of the Monterrey Salient folds on the lower evaporite detachment may have been inhibited by a thick sequence of foreland basin rocks in the northeastern Parras and southern La Popa basins and that the smaller, south verging folds formed where the lower detachment was abandoned and slip was transferred to the shallower detachment, forming a triangle zone at the front of the Sierra Madre orogenic wedge.
Kara Sea freshwater dispersion and export in the late 1990s
Authors: Harms I. H. , Karcher M. J.
Published: August 2005

A regional coupled ice‐ocean model for the Kara Sea, forced with boundary conditions from a large‐scale North Atlantic/Arctic Ocean Model, is used to study dispersion and export of freshwater from Ob and Yenisei rivers toward the Arctic Ocean and the Laptev Sea, for the period 1996–2001. The years 1998 and 1999 were characterized by a strong positive sea level pressure (SLP) anomaly in the Siberian part of the Arctic Ocean. Owing to prevailing northeasterly winds, the SLP anomaly caused a blocking situation, which suppressed the otherwise eastward freshwater export to the Arctic Ocean and Laptev Sea. This reversal of the prevailing circulation scheme led to a dramatic freshening of the Kara Sea through accumulation of low‐saline river water in the central and western parts. Additionally, the Kara Strait inflow from the Barents Sea, which presents the main source for saline Atlantic derived water, was reduced and partly even reversed. The suppressed freshwater export during winter 1998/1999 recovered in the following winter 1999/2000 when a significant pulse of low‐saline surface water left toward the Laptev Sea. The variability of the river discharge plays a minor role for the investigated period because the interannual variability of runoff rates is generally too low to explain the observed hydrographic changes. The results underline the importance of local shelf sea processes for the variability of the freshwater export from the Arctic Shelves to the central Arctic Ocean.
Atomic oxygen profiles (80 to 115 km) derived from Wind Imaging Interferometer/Upper Atmospheric Research Satellite measurements of the hydroxyl and greenline airglow: Local time–latitude dependence
Authors: Russell Jason P. , Ward W. E. , Lowe R. P. , Roble R. G. , Shepherd G. G. , Solheim B.
Published: August 2005

Hydroxyl and oxygen greenline nightglow observations from the Wind Imaging Interferometer (WINDII) are used to examine the local time–latitude variation of atomic oxygen in the mesopause region. Individual hydroxyl and greenline emission profiles from over 5 years of data are converted to oxygen mixing ratio (or concentration) profiles and then binned into local times, latitudes, and seasons. The two derived oxygen profiles from each emission are then combined into a single profile that spans a significant portion of the mesopause region (80 to 115 km). A technique developed earlier that addresses the altitude variability of the emission profiles is used. This level of agreement indicates a high degree of consistency in the radiance observations and in the photochemistry used to convert the emission rates to oxygen profiles. We demonstrate that the atomic oxygen concentration or mixing ratio profiles are very sensitive to local nighttime, and we display the manner in which they vary. The local time variation is primarily due to the tidal dynamics in the atmosphere. Comparisons between our atomic oxygen data set, a simple tidal model, and the TIME‐GCM show good agreement; however, the local time tidal structure of atomic oxygen from MSISE‐90 shows a 180° phase inconsistency. The measured local time oxygen variations vary with season and latitude, and we show that these oscillations are stronger under equinox conditions.
Comparison of gravity wave momentum fluxes estimated by different methods using mesosphere‐stratosphere‐troposphere radar
Authors: Dutta Gopa , Bapiraju B. , Rao P. V. , Sheeba A. I. , Kumar M. C. Ajay , Balasubrahmanyam P. , Basha H. Aleem
Published: August 2005

Mesosphere‐stratosphere‐troposphere radar measurements have been used to estimate momentum flux of gravity waves in a 2–6 hour period in the lower atmosphere over Gadanki (13.5°N, 79.2°E), a tropical station. Different methods have been adopted to compute momentum flux profiles, and a comparative study shows that momentum flux estimates produced by a hybrid method (Worthington and Thomas, 1996) which measures the vertical wind with a vertical beam and the horizontal wind with a pair of radial beams and those obtained by direct computation of spatial covariances ( and ) show satisfactory agreement. The symmetric beam radar method of Vincent and Reid (1983) has the unique advantage since it does not require vertical beam measurement, and it is found to produce momentum flux estimates compatible with other methods except in high wind shear zones. It is observed that the result of momentum flux obtained by the symmetric beam method shows excellent matching with other methods when the average of vertical winds derived from E‐W and N‐S beams is used in the formula for both zonal and meridional fluxes.
Fundamental challenge in simulation and prediction of summer monsoon rainfall
Authors: Wang Bin , Ding Qinghua , Fu Xiouhua , Kang In‐Sik , Jin Kyung , Shukla J. , Doblas‐Reyes Francisco
Published: August 2005

The scientific basis for two‐tier climate prediction lies in the predictability determined by the ocean and land surface conditions. Here we show that the state‐of‐the‐art atmospheric general circulation models (AGCMs), when forced by observed sea surface temperature (SST), are unable to simulate properly Asian‐Pacific summer monsoon rainfall. All models yield positive SST‐rainfall correlations in the summer monsoon that are at odds with observations. The observed lag correlations between SST and rainfall suggest that treating monsoon as a slave possibly results in the models' failure. We demonstrate that an AGCM, coupled with an ocean model, simulates realistic SST‐rainfall relationships; however, the same AGCM fails when forced by the same SSTs that are generated in its coupled run, suggesting that the coupled ocean‐atmosphere processes are crucial in the monsoon regions where atmospheric feedback on SST is critical. The present finding calls for reshaping of current strategies for monsoon seasonal prediction. The notion that climate can be modeled and predicted by prescribing the lower boundary conditions is inadequate for validating models and predicting summer monsoon rainfall.
On the optimum time of integration for estimation of momentum flux from VHF radar data
Authors: Dutta Gopa , Rao P. V. , Kumar M. C. Ajay , Kumar P. Vinay , Basha H. Aleem , Anandan V. K. , Ghosh A. K.
Published: August 2005

VHF radar at Gadanki (13.5°N, 79.2°E) was operated continuously for 24 hours to obtain a unique set of high resolution (150 m in height and 2.5 min. in time) wind data in the troposphere and lower stratosphere. This high quality wind data have been used to estimate momentum flux of short period (<2 hr) wind fluctuations and the associated uncertainties. Error analysis has been carried out by varying the length of integration time. We show that an optimal time of averaging of about 15–16 hrs minimizes the error at a value nearly equal to the irreducible error observed by an ideal anemometer measuring u, v and w at a point.
Discrepancies between formaldehyde measurements and methane oxidation model predictions in the Antarctic troposphere: An assessment of other possible formaldehyde sources
Authors: Riedel K. , Allan W. , Weller R. , Schrems O.
Published: August 2005

Formaldehyde (HCHO) is a key intermediate in the photooxidation of methane by hydroxyl radicals. Through its photolysis, it is also a source for free radicals in the troposphere. Owing to these reactions, HCHO influences the oxidation capacity of the atmosphere and is a suitable species to test our current understanding of atmospheric oxidation pathways. Especially in polar regions, discrepancies between measurements and model calculations exist. Though recent investigations in the Arctic suggest that HCHO emissions from the snow surface might act as the missing source, the question remains unresolved for the Antarctic. We compare year‐round HCHO measurements in Antarctica with model results from a simple photochemical box model. The observed ambient HCHO mixing ratios cannot be explained by methane photooxidation alone. Inclusion of HCHO emissions from the snow surface makes the model results and measurements consistent, but significantly higher emissions than those derived in the Arctic are needed to explain the observed HCHO mixing ratios. We discuss and model other possible sources such as oxidation of dimethylsulfide (DMS), isoprene, ethene, propene, and the effect of halogens, that may be responsible for the enhanced HCHO mixing ratios in the marine Antarctic troposphere. We find that, for the largest HCHO mixing ratio measured, all potential gas‐phase HCHO precursors (including methane) are likely to generate only 20–40% of the required HCHO. If the remaining HCHO is produced by a flux from the snow, the flux required is 1.9–2.5 × 1013 molecules m−2 s−1 if the boundary layer height is 40–50 m.
A multiple‐layer canopy scattering model to simulate shortwave radiation distribution within a homogeneous plant canopy
Authors: Zhao Wenguang , Qualls Russell J.
Published: August 2005

A multiple‐layer canopy scattering model to estimate shortwave radiation distribution within a wheat canopy was derived mathematically, which incorporated processes of radiation penetration through gaps between leaves, and radiation absorption, reflection, and transmission in leaf layers. The model is able to simulate the multiple scattering processes that occur among different canopy layers and to predict the vertical distributions of upward, downward, and reflected shortwave radiation within the canopy, as well as the magnitude of subcanopy radiation that penetrates to the soil surface. One of the primary advantages of this model, in contrast to other models, is that the multiple scattering processes are represented by a set of linear simultaneous equations that can be solved in a single pass through the equations, without iteration. This achieves computational economy while still accounting for the details of multiple scattering of radiation within the canopy. Stability analyses of the model showed that the canopy, with a leaf area index within a normal field range from 0 to 7, needed to be divided into about 50 or more layers in order to converge upon its final solution. Satisfactory agreement was obtained between model results and field measurements for downward shortwave radiation impinging on the soil surface below the canopy, and upward reflected radiation above the canopy, both for daily total values and for the 20‐min averages throughout the diurnal cycle.
Nonlinear dynamic model and neural coding of neuronal network with the variable coupling strength in the presence of external stimuli
Authors: Jiao Xianfa , Wang Rubin
Published: August 2005

By accounting for the variation of coupling strength, we present a dynamic model of the neuronal oscillator network subject to external stimulus and noise, and introduce an average coupling-pair number density to describe the collective behavior of the neuronal oscillator network. We use the coupling-pair number density as a distributed coding pattern of neuronal network. The numerical simulations reveal that a weaker stimulus has little impact on the coding of neuronal network; whereas a stronger stimulus enhances the synchronized activity of neuronal network and the coupling between the oscillators. The numerical simulations also show that the combined stimuli with different modalities have a correlative impact on the neural coding, and the stronger stimulus dominates the neural coding.
Steric effects in state-to-state scattering of OH (Π3∕22,J=3∕2,f) by HCl
Authors: Cireasa R. , Moise A. , ter Meulen J. J.
Published: August 2005

In this paper we address stereodynamical issues in the inelastic encounters between OH (Χ2Π) radicals and HCl (Χ1Σ+). The experiments were performed in a crossed molecular-beam machine at the nominal collision energy of 920cm−1. Prior to the collisions, the OH molecules were selected using a hexapole in a well-defined rotational state v=0, Ω=3∕2, J=3∕2, MJ=3∕2, f, and subsequently oriented in a homogeneous electrical field. We have measured rotationally resolved relative cross sections for collisions in which OH is oriented with either the O side or the H side towards HCl, from which we have calculated the corresponding steric asymmetry factors S. The results are presented in comparison with data previously obtained by our group for the inelastic scattering of OH by CO (Ecoll=985cm−1) and N2 (Ecoll=985cm−1) studied under similar experimental conditions. The dissimilarity in the behavior of the OH+HCl system revealed by this comparison is explained on the basis of the difference in the anisotropy of the interaction potential governing the collisions. The interpretation of the data takes into account the specific features of both nonreactive and reactive parts of the potential-energy surface. The results indicate that the scattering dynamics at this collision energy may be influenced by the HO–HCl van der Waals well and by reorientation effects determined by the long-range electrostatic forces and, furthermore, may involve reactive collisions.
On the relationships between kinetic schemes and two-state single molecule trajectories
Authors: Flomenbom Ophir , Klafter Joseph
Published: August 2005

Trajectories of a signal that fluctuates between two states which originate from single molecule activities have become ubiquitous. Common examples are trajectories of ionic flux through individual membrane channels and of photon counts collected from diffusion, activity, and conformational changes of biopolymers. By analyzing the trajectory, one wishes to deduce the underlying mechanism, which is usually described by a multisubstate kinetic scheme. In previous works [O. Flomenborn, J. Klafter, and A. Szabo, Biophys. J. 88, 3780 (2005); O. Flomenbom and J. Klafter, Acta Phys. Pol. B 36, 1527 (2005)], we divided kinetic schemes that generate two-state trajectories into two types: reducible schemes and irreducible schemes. A full characterization of the reducible ones was given. We showed that all the information in trajectories generated from reducible schemes is contained in the waiting time probability density functions (PDFs) of the two states. It follows that reducible schemes with the same waiting time PDFs are not distinguishable; namely, such schemes lead to identical two-state trajectories in the statistical sense. In this work, we further characterize the topologies of kinetic schemes, now of irreducible schemes, and further study two-state trajectories from the two types of scheme. We suggest various methods for extracting information about the underlying kinetic scheme from the trajectory (e.g., calculate the binned successive waiting times PDFs and analyze the ordered waiting time trajectories), and point out the advantages and disadvantages of each. We show that the binned successive waiting times PDFs are not only more robust than other functions when analyzing finite trajectories, but contain, in most cases, more information about the underlying kinetic scheme than other functions in the limit of infinitely long trajectories. For some cases, however, analyzing the ordered waiting times trajectory may supply unique information about the underlying kinetic scheme.
Structure and stability of Ne+Hen: Experiment and diffusion quantum Monte Carlo theory with “on the fly” electronic structure
Authors: Brindle Carrie A. , Prado Melissa R. , Janda Kenneth C. , Halberstadt Nadine , Lewerenz Marius
Published: August 2005

New data are reported for the mass-spectrometry fragmentation patterns of helium clusters, either pure or containing a Ne or an Ar atom. The patterns for Hen+ and Ar+Hen show clear evidence of structure, while those of Ne+Hen do not. To better understand the surprising result for the Ne+Hen fragments, diffusion quantum Monte Carlo (DMC) calculations of the energies and structural properties of these ions were performed using a diatomics-in-molecule (DIM) parametrization of the potential energy. Using DIM for electronic energy evaluation allows us to sample 109 configurations even for a cluster as large as Ne+He14. The results of the DMC calculation are very surprising. For n>7, the DMC random walkers rarely venture within 100cm−1 of the minimum potential energy. Analysis of the resulting particle density distributions shows that the zero-point energy does more than spread the wave function around the potential-energy minima, resulting in very diffuse wave functions. For some of the clusters the quantum effects nearly exclude the region of the potential minimum from the overall wave function. An important result of this effect is that the incremental bonding energy of the nth helium atom varies quite smoothly with n, for n>5. This eliminates the expected shell structure and explains the lack of magic-number-type features in the data.
Geometries, stabilities, and electronic properties of different-sized ZrSin (n=1–16) clusters: A density-functional investigation
Authors: Wang Jin , Han Ju-Guang
Published: August 2005

The ZrSin (n=1–16) clusters with different spin configurations have been systematically investigated by using the density-functional approach. The total energies, equilibrium geometries, growth-pattern mechanisms, natural population analysis, etc., are discussed. The equilibrium structures of different-sized ZrSin clusters can be determined by two evolution patterns. Theoretical results indicate that the most stable ZrSin (n=1–7) geometries, except ZrSi3, keep the analogous frameworks as the lowest-energy or the second lowest-energy Sin+1 clusters. However, for large ZrSin (n=8–16) clusters, Zr atom obviously disturbs the framework of silicon clusters, and the localized position of the transition-metal (TM) Zr atom gradually varies from the surface insertion site to the concave site of the open silicon cage and to the encapsulated site of the sealed silicon cage. It should be mentioned that the lowest-energy sandwichlike ZrSi12 geometry is not a sealed structure and appears irregular as compared with other TM@Si12 (TM=Re,Ni). The growth patterns of ZrSin (n=1–16) clusters are concerned showing the Zr-encapsulated structures as the favorable geometries. In addition, the calculated fragmentation energies of the ZrSin (n=1–16) clusters manifest that the magic numbers of stabilities are 6, 8, 10, 14, and 16, and that the fullerenelike ZrSi16 is the most stable structure, which is in good agreement with the calculated atomic binding energies of ZrSin (n=8–16) and with available experimental and theoretical results. Natural population analysis shows that the natural charge population of Zr atom in the most stable ZrSin (n=1–16) structures exactly varies from positive to negative at the critical-sized ZrSi8 cluster; furthermore, the charge distribution around the Zr atom appears clearly covalent in character for the small- or middle-sized clusters and metallic in character for the large-sized clusters. Finally, the properties of frontier orbitals and polarizabilities of ZrSin are also discussed.
Stationary fronts due to weak thermal effects in models of catalytic oxidation
Authors: Sheintuch Moshe , Nekhamkina Olga
Published: August 2005

We analyze the possible existence of an infinite number of stationary front solutions in a microkinetic model of a catalytic reaction coupled with weak enthalpy effects in the domain of kinetics bistability. The kinetic model incorporates three steps: dissociative oxygen adsorption, reactant adsorption and desorption, and surface reaction. The infinitude of stationary front solutions emerges due to the lack of intercrystallites communication of surface species in supported catalysts; thermal conductions and gas-phase diffusion are the only means of interaction. Incorporation of surface species diffusion leads to a very slow front motion. We complement this analysis with simulations of stationary states on one- (wire and ring) and two-dimensional (disk) systems which may be subject to control or to fluid flow. These results account for certain experimental results and may have implications for various technological problems.
Boson peak in supercooled liquids: Time domain observations and mode coupling theory
Authors: Cang Hu , Li Jie , Andersen Hans C. , Fayer M. D.
Published: August 2005

Optical heterodyne-detected optical Kerr effect (OHD-OKE) experiments are presented for the supercooled liquid acetylsalicylic acid (aspirin - ASP). The ASP data and previously published OHD-OKE data on supercooled dibutylphthalate (DBP) display highly damped oscillations with a periods of ∼2ps as the temperature is reduced to and below the mode coupling theory (MCT) temperature TC. The oscillations become more pronounced below TC. The oscillations can be interpreted as the time domain signature of the boson peak. Recently a schematic MCT model, the Sjögren model, was used to describe the OHD-OKE data for a number of supercooled liquids by Götze and Sperl [W. Götze and M. Sperl, Phys. Rev. E 92, 105701 (2004)] , but the short-time and low-temperature behaviors were not addressed. Franosch et al. [T. Franosch, W. Gotze, M. R. Mayr, and A. P. Singh, Phys. Rev. E 55, 3183 (1997)] found that the Sjögren model could describe the boson peak observed by depolarized light-scattering (DLS) experiments on glycerol. The OHD-OKE experiment measures a susceptibility that is a time domain equivalent of the spectrum measured in DLS. Here we present a detailed analysis of the ASP and DBP data over a broad range of times and temperatures using the Sjögren model. The MCT schematic model is able to describe the data very well at all temperatures and relevant time scales. The trajectory of MCT parameters that fit the high-temperature data (no short-time oscillations) when continued below TC results in calculations that reproduce the oscillations seen in the data. The results indicate that increasing translational-rotational coupling is responsible for the appearance of the boson peak as the temperature approaches and drops below TC.
Ionization degree for strong evaporation of metals
Authors: Gusarov Andrey V. , Aoki Kazuo
Published: August 2005

Kinetic equations for ions and neutrals are numerically solved in the plasma sheath formed at a condensed phase when strong evaporation is taking place. The Boltzmann distribution is assumed for electrons. A weakly ionized vapor with the Debye length much shorter than the mean free path is considered. This is typical for laser evaporation of metals. Under these conditions, the sheath consists of a Knudsen layer and a thin charge separation layer between the Knudsen layer and the condensed phase. The self-consistent electrostatic field in the Knudsen layer is obtained from the quasineutrality condition. The potential barrier in the charge separation layer is determined by the charge balance. Kinetic boundary conditions for neutrals and charges are estimated by the detailed balance principle from the parameters of the saturated vapor. The transport of charges in the sheath is controlled by ions and depends on ion-neutral collisions and the self-consistent electrostatic field. Ionization degree in the vapor formed by strong evaporation increases with the Mach number and can attain values about 30% higher than the ionization degree in the saturated vapor. Two factors contribute to this increase. The first is the drop of the potential barrier in the charge separation layer and the second is the strengthening of the field in the Knudsen layer. The ionization equilibrium may be disturbed by a considerable excess of charges.
Analysis of shape effects on the piezoresponse in ferroelectric nanograins with and without adsorbates
Authors: Peter F. , Rüdiger A. , Dittmann R. , Waser R. , Szot K. , Reichenberg B. , Prume K.
Published: August 2005

Using BaTiO3 as a piezoelectric model system we compare a finite element model with experimental data to demonstrate the impact of grain topography on the in-plane piezoelectric response at the perimeter. Our findings emphasize the need for a careful consideration of both electric field and piezoelectric tensor orientation. An analysis is given showing that the in-plane piezoresponse is a function of two directions of the electric field, whereas the out-of-plane response is a function of all three directions of the applied field. The effect of an adsorbate layer on the piezoelectric response is quantified with typical material parameters.
Quantification of the H content in diamondlike carbon and polymeric thin films by reflection electron energy loss spectroscopy
Authors: Yubero F. , Rico V. J. , Espinós J. P. , Cotrino J. , González-Elipe A. R.
Published: August 2005

A nondestructive method to determine the hydrogen content at the surface of diamondlike carbon and polymeric thin films is proposed. The method relies on the analysis of the elastic peak produced by backscattering of electrons from the hydrogen atoms present at the sample surface. Quantitative analysis of the H content at the surface is achieved through use of a phenomenological sensitivity factor for elastic electron backscattering by H atoms with respect to other atoms present at the surface of reference polymeric samples. The validity of the method is checked with elastic recoil detection measurements and infrared spectroscopy analysis of the same samples. The accuracy of the method in the determination of H content at the sample surface is estimated to be ±10%.
Magnetization-graded ferromagnets: The magnetic analogs of semiconductor junction elements
Authors: Mantese Joseph V. , Micheli Adolph L. , Schubring Norman W. , Hayes R. W. , Srinivasan G. , Alpay S. P.
Published: August 2005

Compositionally graded ferrites are formed as the magnetic analogs of semiconductor junction devices. The internal, or the “built-in,” magnetic field is intrinsic to the structure and is determined from ferromagnetic resonance microscopy. Magnetic analysis of a nickel–zinc–ferrite system in terms of its spatially dependent order parameter, the magnetization, yields a value for the internal magnetic field consistent with experimental observations. Our results are extended to the general class of ferroic and other “smart” materials via a spatially dependent free-energy potential.
In-plane microwave dielectric properties of paraelectric barium strontium titanate thin films with anisotropic epitaxy
Authors: Simon W. K. , Akdogan E. K. , Safari A. , Bellotti J. A.
Published: August 2005

In-plane dielectric properties of ⟨110⟩ oriented epitaxial (Ba0.60Sr0.40)TiO3 thin films in the thickness range from 25–1200nm have been investigated under the influence of anisotropic epitaxial strains from ⟨100⟩ NdGaO3 substrates. The measured dielectric properties show strong residual strain and in-plane directional dependence. Below 150nm film thickness, there appears to be a phase transition due to the anisotropic nature of the misfit strain relaxation. In-plane relative permittivity is found to vary from as much as 500–150 along [11¯0] and [001] respectively, in 600nm thick films, and from 75 to 500 overall. Tunability was found to vary from as much as 54% to 20% in all films and directions, and in a given film the best tunability is observed along the compressed axis in a mixed strain state, 54% along [11¯0] in the 600nm film for example.
Boron distribution in silicon after multiple pulse excimer laser annealing
Authors: Monakhov E. V. , Svensson B. G. , Linnarsson M. K. , La Magna A. , Italia M. , Privitera V. , Fortunato G. , Cuscunà M. , Mariucci L.
Published: August 2005

We have studied B redistribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted with energies of 1 and 10keV and doses of 1×1014 and 1×1015cm−2. ELA with the number of pulses from 1 to 100 was performed at room temperature and 450°C in vacuum. Irrespective of the implantation parameters and the ELA conditions used, a pile-up in the B concentration is observed near the maximum melting depth after ten pulses of ELA. Moreover, a detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. Besides, an increase in the carrier concentration is observed at the maximum melt depth, suggesting electrical activity of the accumulated B. Formation of Si-B complexes and vacancy accumulation during multiple ELA are discussed as possible mechanisms for the B build-up.
Germination response to heat and smoke of 22 Poaceae species from grassy woodlands
Authors: Clarke S. , French K.
Published: August 2005

Grasses form an important component of grassy woodlands, although their response to fire has been understudied. In this study, fire germination responses of 22 Poaceae species from an endangered grassy-woodland community in eastern Australia were investigated. Seeds of 20 native and two exotic species were subjected to heat (no heat, 40, 80 and 120°C) and smoke treatment (10% dilution smoke water) and the percentage germination was compared. Germination response of species showed no consistent pattern to phylogeny and was highly variable. Germination in six species was unaffected by the application of heat or smoke. In five species, heat, irrespective of smoke application, influenced germination. Smoke, irrespective of heat treatment, influenced six species. For a further six species, the effect of smoke varied with temperature. These results suggest that fire regimes will influence the recruitment of grass species differentially and maintaining regional species richness is likely to require the maintenance of a heterogeneous fire regime across the landscape.
Higher-order thalamic relays burst more than first-order relays
Authors: Ramcharan E. J. , Gnadt J. W. , Sherman S. M.
Published: August 2005

There is a strong correlation between the behavior of an animal and the firing mode (burst or tonic) of thalamic relay neurons. Certain differences between first- and higher-order thalamic relays (which relay peripheral information to the cortex versus information from one cortical area to another, respectively) suggest that more bursting might occur in the higher-order relays. Accordingly, we recorded bursting behavior in single cells from awake, behaving rhesus monkeys in first-order (the lateral geniculate nucleus, the ventral posterior nucleus, and the ventral portion of the medial geniculate nucleus) and higher-order (pulvinar and the medial dorsal nucleus) thalamic relays. We found that the extent of bursting was dramatically greater in the higher-order than in the first-order relays, and this increased bursting correlated with lower spontaneous activity in the higher-order relays. If bursting effectively signals the introduction of new information to a cortical area, as suggested, this increased bursting may be more important in corticocortical transmission than in transmission of primary information to cortex.
Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America
Authors: Strömberg Caroline A. E.
Published: August 2005

Because of a dearth of Cenozoic grass fossils, the timing of the taxonomic diversification of modern subclades within the grass family (Poaceae) and the rise to ecological dominance of open-habitat grasses remain obscure. Here, I present data from 99 Eocene to Miocene phytolith assemblages from the North American continental interior (Colorado, Nebraska, Wyoming, and Montana/Idaho), constituting the only high-resolution mid-Cenozoic record of grasses. Analyses of these assemblages show that open-habitat grasses had undergone considerable taxonomic diversification by the earliest Oligocene (34 million years ago) but that they did not become ecologically dominant in North America until 7–11 million years later (Late Oligocene or Early Miocene). This pattern of decoupling suggests that environmental changes (e.g., climate changes), rather than taxonomic radiations within Poaceae, provided the key opportunity for open-habitat grasses to expand in North America.
Self-organization of foraging behaviour: From simplicity to complexity without goals
Authors: Provenza Frederick D , Villalba Juan J , Cheney Carl D , Werner Scott J
Published: August 2005

A herbivore faces challenges while foraging—ongoing changes in its physiological condition along with variation in the nutrient and toxin concentrations of foods, spatially and temporally—that make selecting a nutritious diet a vital affair. Foraging behaviours arise from simple rules that operate across levels of resolution from cells and organs to individuals and their interactions with social and physical environments. At all these levels, behaviour is a function of its consequences: a behaviour operating on the environment to induce changes is itself changed by those events. Thus, behaviour emerges from its own functioning—behaviour self-organizes-not from that of its surroundings. This ostensible autonomy notwith-standing, no self-organizing system (cell, organ, or individual) is independent of its environs because existence consists of an ongoing exchange of energy and matter. According to this view, the notion of cause and effect is replaced with functional relationships between behaviours and environmental consequences. Changes in physical environments alter the distribution, abundance, nutritional, and toxicological characteristics of plants, which affect food preference. Social interactions early in life influence behaviour in various ways: animals prefer familiar foods and environments, and they prefer to be with companions. Animals in unfamiliar environments often walk farther, ingest less food, and suffer more from malnutrition and toxicity than animals in familiar environments. An individual's food preferences—and its ability to discriminate familiar from novel foods—arise from the functional integration of sensory (smell, taste, texture) and postingestive (effects of nutrients and toxins on chemo-, osmo-, and mechano-receptors) effects. The ability to discriminate among foods is critical for survival: all problems with poisonous plants are due to an inability to discriminate or a lack of alternatives. Animals eat a variety of foods as a result of nearing or exceeding tolerance limits for sensory and postingestive effects unique to each food. After eating any food too frequently or excessively, the likelihood increases that animals will eat alternative foods owing to exceeding sensory-, nutrient-, and toxin-specific tolerance limits. Cyclic patterns of intake of a variety of foods reflect seemingly chaotic interactions among flavours, nutrients, and toxins interacting along continua.