bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral reflectance of whitecaps
Authors: Kokhanovsky A. A.
Published: May 2004

Spectral properties of whitecaps are of importance for color ocean remote sensing and aerosol optical thickness probing from satellite‐based instruments. They also influence planetary albedo and climate. In particular, whitecaps may affect the response of the climate system to changes in greenhouse gases and other atmospheric constituents. Several experimental measurements of whitecap spectral reflectance have been performed both in the surf zone and in the open ocean, which indicate that oceanic foam cannot be considered as a gray body (e.g., for satellite remote sensing techniques). This paper is devoted to the interpretation of experiments performed in terms of the radiative transfer theory. Only the case of a semi‐infinite foam is studied in detail. However, results can be easily extended to the case of finite foamed media having large optical thickness. The model introduced is capable of explaining main features observed, like a sharp decrease of the foam spectral reflectance in the infrared as compared with the visible part of the electromagnetic spectrum and a high correlation of the foam reflectance R and the water absorption coefficient α. A simple method to retrieve the spectral dependence of α from the spectral foam reflectance R is proposed.
Tropospheric ozone over the North Pacific from ozonesonde observations
Authors: Oltmans S. J. , Johnson B. J. , Harris J. M. , Thompson A. M. , Liu H. Y. , Chan C. Y. , Vömel H. , Fujimoto T. , Brackett V. G. , Chang W. L. , Chen J.‐P. , Kim J. H. , Chan L. Y. , Chang H.‐W.
Published: May 2004

As part of the Transport and Chemical Evolution over the Pacific (TRACE‐P) mission, ozonesondes were used to make ozone vertical profile measurements at nine locations in the North Pacific. At most of the sites there is a multiyear record of observations. From locations in the western Pacific (Hong Kong; Taipei; Jeju Island, Korea; and Naha, Kagoshima, Tsukuba, and Sapporo, Japan), a site in the central Pacific (Hilo, Hawaii), and a site on the west coast of the United States (Trinidad Head, California) both a seasonal and event specific picture of tropospheric ozone over the North Pacific emerges. Ozone profiles over the North Pacific generally show a prominent spring maximum throughout the troposphere. This maximum is tied to the location of the jet stream and its influence on stratosphere‐troposphere exchange and the increase in photochemical ozone production through the spring. Prominent layers of enhanced ozone in the middle and upper troposphere north of about 30°N seem to be more closely tied to stratospheric intrusions while biomass burning leads to layers of enhanced ozone in the lower and upper troposphere at Hong Kong (22°N) and Taipei (25°N). The lower free tropospheric layers at Hong Kong are associated with burning in SE Asia, but the upper layer may be associated with either equatorial Northern Hemisphere burning in Africa or SE Asian biomass burning. In the boundary layer at Taipei very high mixing ratios of ozone were observed that result from pollution transport from China in the spring and local urban pollution during the summer. At the ozonesonde site near Tokyo (Tsukuba, 36°N) very large enhancements of ozone are seen in the boundary layer in the summer that are characteristic of urban air pollution. At sites in the mid and eastern Pacific the signature of transport of polluted air from Asia is not readily identifiable from the ozonesonde profile. This is likely due to the more subtle signal and the fact that from the ozone profile and meteorological data by themselves it is difficult to identify such a signal. During the TRACE‐P intensive campaign period (February–April 2001), tropospheric ozone amounts were generally typical of those seen in the long‐term records of the stations with multiyear soundings. The exception was the upper troposphere over Hong Kong and Taipei where ozone amounts were lower in 2001.
Climate Prediction Center global monthly soil moisture data set at 0.5° resolution for 1948 to present
Authors: Fan Yun , van den Dool Huug
Published: May 2004

We have produced a 0.5° × 0.5° monthly global soil moisture data set for the period from 1948 to the present. The land model is a one‐layer “bucket” water balance model, while the driving input fields are Climate Prediction Center monthly global precipitation over land, which uses over 17,000 gauges worldwide, and monthly global temperature from global Reanalysis. The output consists of global monthly soil moisture, evaporation, and runoff, starting from January 1948. A distinguishing feature of this data set is that all fields are updated monthly, which greatly enhances utility for near‐real‐time purposes. Data validation shows that the land model does well; both the simulated annual cycle and interannual variability of soil moisture are reasonably good against the limited observations in different regions. A data analysis reveals that, on average, the land surface water balance components have a stronger annual cycle in the Southern Hemisphere than those in the Northern Hemisphere. From the point of view of soil moisture, climates can be characterized into two types, monsoonal and midlatitude climates, with the monsoonal ones covering most of the low‐latitude land areas and showing a more prominent annual variation. A global soil moisture empirical orthogonal function analysis and time series of hemisphere means reveal some interesting patterns (like El Niño‐Southern Oscillation) and long‐term trends in both regional and global scales.
Using chaotic interrogation and attractor nonlinear cross-prediction error to detect fastener preload loss in an aluminum frame
Authors: Todd M. D. , Erickson K. , Chang L. , Lee K. , Nichols J. M.
Published: May 2004

Structural health monitoring is an important field concerned with assessing the current state (or “health”) of a structural system or component with regard to its ability to perform its intended function appropriately. One approach to this problem is identifying appropriate features obtained from time series vibration responses of the structure that change as structural degradation occurs. In this work, we present a novel technique adapted from the nonlinear time series prediction community whereby the structure is excited by an applied chaotic waveform, and predictive maps built between structural response attractors are used as the feature space. The structural response is measured at several points on the structure, and pairs of attractors are used to predict each other. As the dynamics of the structure change due to damage, the prediction error rises. This approach is applied to detecting the preload loss in a bolted joint in an aluminum frame structure.
Marginal Willingness to Pay for Public Investment under Urban Environmental Risk: The Case of Municipal Water Use
Authors: Hagihara Kiyoko , Asahi Chisato , Hagihara Yoshimi
Published: May 2004

Marginal willingness to pay for public investment under urban environmental risk is considered in this paper. In particular, we present a model that takes into account a bounded rationality on the ability of risk perception, the information situation, and people's threshold acceptance of risk. A case study of the evaluation of risk in municipal water use is presented. In order to investigate the information situation and risk perception of people, a questionnaire survey was conducted. The survey reveals that risk awareness is a factor in drinking water, and that people change their choice based on risk information. The effects of information on risk and public investment are then considered. From some numerical examples, marginal willingness to pay is found to be low in the case of high risk, because of consumers' self-defensive activities. In other words, marginal willingness to pay for public investment is high when there is little or no averting behavior. Moreover, it is shown that consumers' perception of risk is dependent largely on information on risk, countermeasures taken by public authorities, and overconfidence in private averting goods.
Promoting Linkage to Foreign Transnational in a ‘Tiger’ State: Singapore and the Local Industry Upgrading Programme
Authors: Coe Neil M , Perry Martin
Published: May 2004

Singapore is a key destination for high-technology foreign direct investment in the Asia Pacific, particularly in the areas of disk drives and semiconductors, but increasingly in terms of knowledge-based services. Since the 1980s the government has made strenuous efforts to harness the innovative capacity of foreign transnational corporations through a series of policy initiatives aimed at facilitating a variety of forms of technology transfer to locally owned firms. This paper critically evaluates the impacts of these policy initiatives, and more specifically the Local Industry Upgrading Programme (LIUP), through case studies of the electronics and software sectors. The analysis suggests that supplier upgrading has been limited in the electronics sector, but that horizontal partnership arrangements, as evidenced by the software sector LIUP, may have more beneficial impacts.
Cognitive Compensations for Blindness in Children: An Investigation Using Odour Naming
Authors: Wakefield Claire E , Homewood Judi , Taylor Alan J
Published: May 2004

Historically, blindness has been associated with compensation for the loss of vision by the other senses. However, research to date has focused on perceptual compensations, largely ignoring possible cognitive compensations. We explored the notion that cognitive skills of blind children may facilitate performance in apparently perceptual tasks, by investigating the cognitive factors related to naming a familiar odour. Eighty-three children participated in olfactory and cognitive tasks (thirty-two early-blind, five late-blind, fourteen low-vision, and thirty-two sighted). In the olfactory tasks, the early-blind children performed significantly better than the sighted children on the odour-naming task but not on the odour-sensitivity task. From the cognitive tasks, scores on a nonvisualisable word-pairs task and a sound – word-pairs task were significantly higher for early-blind children and were highly correlated with odour-naming score. The early-blind children outperformed the sighted controls on a task of directed attention. The groups did not differ on memory for a story or for visualisable word pairs. The results suggest that blind children enjoy an advantage in tasks that assess nonvisual memory for paired associates and directed attention, and that superiority on these tasks facilitates performance in the odour-naming task. Other data suggest that sighted children rely on visualisation as a strategy to aid their performance on the cognitive tasks, and are disadvantaged when these strategies cannot be utilised.
Illusory Causal Crescents: Misperceived Spatial Relations Due to Perceived Causality
Authors: Scholl Brian J , Nakayama Ken
Published: May 2004

When an object A moves toward an object B until they are adjacent, at which point A stops and B starts moving, we often see a collision—ie we see A as the cause of B's motion. The spatiotemporal parameters which mediate the perception of causality have been explored in many studies, but this work is seldom related to other aspects of perception. Here we report a novel illusion, wherein the perception of causality affects the perceived spatial relations among two objects involved in a collision event: observers systematically underestimate the amount of overlap between two items in an event which is seen as a causal collision. This occurs even when the causal nature of the event is induced by a surrounding context, such that estimates of the amount of overlap in the very same event are much improved when the event is displayed in isolation, without a ‘causal’ interpretation. This illusion implies that the perception of causality does not proceed completely independently of other visual processes, but can affect the perception of other spatial properties.
The Ups and Downs of Face Perception: Evidence for Holistic Encoding of Upright and Inverted Faces
Authors: Murray Janice E
Published: May 2004

A visual-search task was used to investigate the influence of facial organisation on discrimination of an internal facial feature. Participants searched for a downturned mouth in arrays of one to six faces that differed only in the target feature, with distractor faces containing an upturned mouth. Feature search was tested in four different face contexts: upright unaltered faces, inverted unaltered faces, upright faces in which the internal features were scrambled, or inverted scrambled faces. Normal face organisation facilitated feature search in upright faces, but slowed it in inverted faces. These findings demonstrate an interdependence of features and their configuration in the perceptual analysis of both upright and inverted faces.
Rapid Image-Segmentation and Perceptual Transparency Share a Process Which Utilises X-Junctions Generated by Temporal Integration in the Visual System
Authors: Mitsudo Hiroyuki
Published: May 2004

Perceptual transparency requires local same-polarity X-junctions, which can also be generated by temporal integration under natural dynamic conditions. In this study, segmentation performance and target appearance were measured for a uniform gray target embedded in a random-dot frame presented with a temporally adjacent mask. Although static cues for both segmentation and transparency were unavailable, transparency was observed only when collinear same-polarity edges reduced backward masking, in both the fovea and the perifovea. These results suggest that the visual system has a common underlying mechanism for rapid segmentation and transparency, which utilises same-polarity X-junctions generated by temporal integration.
Metal-Mediated Pseudo Coordination Isomerism in Complexes of Mixed Neutral Didentate and Dianionic Tridentate Pyridine-Containing Ligands
Authors: Alcock Nathaniel W. , Clarkson Guy J. , Lawrance Geoffrey A. , Moore Peter
Published: May 2004

Reaction of nickel(II) or copper(II) acetate with 2-(aminomethyl)pyridine 1 and pyridine-2,6-dicarboxylate ion 2 in aqueous methanol in a 1 : 1 : 1 molar ratio leads to the crystallization in high yield of exclusively one product in each case. For nickel(II), a neutral mixed-ligand complex [Ni · 1 · 2 · (OH2)] is obtained, whereas with copper(II) an ionic complex [Cu · 12 · (OHCH3)][Cu · 22] forms wherein each complex ion contains exclusively one type of ligand. The outcome appears to be directed by the metal ion employed, the two forms being effectively coordination isomers, albeit differing in central metal ion. The neutral complex [Ni · 1 · 2 · (OH2)] · 4¼H2O crystallizes in the triclinic space group P¯1, with two independent nickel centres and ten (some with partial occupancy) water molecules in the asymmetric unit. Each nickel lies in a distorted octahedral environment, with the three N-donor and O-donor sets occupying meridional positions. A complex system of hydrogen bonding and Π-stacking operates in the crystal, with arrays of complex units arranged in ‘dimer tapes’ surrounded by water molecules. The ionic [Cu · 12 · (OHCH3)][Cu · 22] · 2CH3OH complex crystallizes in the monoclinic P21/c space group. The cation adopts a distorted square-based pyramidal geometry with a coordinated methanol in the axial position, although another is weakly interacting in the other axial site. The anion exists in the previously described octahedral geometry with two meridionally-disposed tridentate ligands with the pyridines disposed in trans positions. Three-dimensional ordering in the structure is directed by ‘ribbons’ of hydrogen bonding.
Simulation, experiment, and evolution: Understanding nucleation in protein S6 folding
Authors: Hubner Isaac A. , Oliveberg Mikael , Shakhnovich Eugene I.
Published: May 2004

In this study, we explore nucleation and the transition state ensemble of the ribosomal protein S6 using a Monte Carlo (MC) Go model in conjunction with restraints from experiment. The results are analyzed in the context of extensive experimental and evolutionary data. The roles of individual residues in the folding nucleus are identified, and the order of events in the S6 folding mechanism is explored in detail. Interpretation of our results agrees with, and extends the utility of, experiments that shift φ-values by modulating denaturant concentration and presents strong evidence for the realism of the mechanistic details in our MC Go model and the structural interpretation of experimental φ-values. We also observe plasticity in the contacts of the hydrophobic core that support the specific nucleus. For S6, which binds to RNA and protein after folding, this plasticity may result from the conformational flexibility required to achieve biological function. These results present a theoretical and conceptual picture that is relevant in understanding the mechanism of nucleation in protein folding.
A steroid modulatory domain on NR2B controlsN-methyl-d-aspartate receptor proton sensitivity
Authors: Jang Ming-Kuei , Mierke Dale F. , Russek Shelley J. , Farb David H.
Published: May 2004

N-methyl-d-aspartate (NMDA) receptor function is modulated by several endogenous molecules, including zinc, polyamines, protons, and sulfated neurosteroids. Zinc, polyamines, and phenylethanolamines exert their respective modulatory effects by exacerbating or relieving tonic proton inhibition. Here, we report that pregnenolone sulfate (PS) uses a unique mechanism for enhancement of NMDA receptor function that is independent of the proton sensor. We identify a steroid modulatory domain, SMD1, on the NMDA receptor NR2B subunit that is critical for both PS enhancement and proton sensitivity. This domain includes the J/K helices in the S2 region of the glutamate recognition site and the fourth membrane transmembrane region (M4). A molecular model based on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor structure suggests that steroid modulatory domain 1 contributes residues to a hydrophobic pocket that is capable of accommodating PS. The results demonstrate that the J/K helices and the fourth membrane transmembrane region participate in transducing allosteric interactions induced by steroid and proton binding to their respective sites.
Placental-specific insulin-like growth factor 2 (
Igf2
) regulates the diffusional exchange characteristics of the mouse placenta
Authors: Sibley C. P. , Coan P. M. , Ferguson-Smith A. C. , Dean W. , Hughes J. , Smith P. , Reik W. , Burton G. J. , Fowden A. L. , Constância M.
Published: May 2004

Restricted fetal growth is associated with postnatal mortality and morbidity and may be directly related to alterations in the capacity of the placenta to supply nutrients. We proposed previously that imprinted genes can regulate nutrient supply by the placenta. Here, we tested the hypothesis that the insulin-like growth factor 2 gene (
Igf2
) transcribed from the placental-specific promoter (P0) regulates the development of the diffusional permeability properties of the mouse placenta. Using mice in which placental-specific
Igf2
had been deleted (P0), we measured the transfer
in vivo
of three inert hydrophilic solutes of increasing size (
14
C-mannitol,
51
CrEDTA, and
14
C-inulin). At embryonic day 19, placental and fetal weights in P0 conceptuses were reduced to 66% and 76%, respectively, of wild type. In P0 mutants, the permeability·surface area product for the tracers at this stage of development was 68% of that of controls; this effect was independent of tracer size. Stereological analysis of histological sections revealed the surface area of the exchange barrier in the labyrinth of the mouse placenta to be reduced and thickness increased in P0 fetuses compared to wild type. As a result, the average theoretical diffusing capacity in P0 knockout placentas was dramatically reduced to 40% of that of wild-type placentas. These data show that placental
Igf2
regulates the development of the diffusional exchange characteristics of the mouse placenta. This provides a mechanism for the role of imprinted genes in controlling placental nutrient supply and fetal growth. Altered placental
Igf2
could be a cause of idiopathic intrauterine growth restriction in the human.
Predictive Performance and Variability of the Cardiac Anesthesia Risk Evaluation Score
Authors: Ouattara Alexandre , Niculescu Michaëla , Ghazouani Sarra , Babolian Ario , Landi Marc , Lecomte Patrick , Boccara Gilles , Varnous Sheida , Leprince Pascal , Riou Bruno , Coriat Pierre
Published: May 2004

Background

The Cardiac Anesthesia Risk Evaluation (CARE) score, a simple Canadian classification for predicting outcome after cardiac surgery, was evaluated in 556 consecutive patients in Paris, France. The authors compared its performance to those of two multifactorial risk indexes (European System for Cardiac Operative Risk Evaluation [EuroSCORE] and Tu score) and tested its variability between groups of physicians (anesthesiologists, surgeons, and cardiologists).

Methods

Each patient was simultaneously assessed using the three scores by an attending anesthesiologist in the immediate preoperative period. In a blinded study, the CARE score category was also determined by a cardiologist the day before surgery, by a surgeon in the operating room, and by a second anesthesiologist at arrival in intensive care unit. Calibration and discrimination for predicting outcomes were assessed by goodness-of-fit test and area under the receiver operating characteristic curve, respectively. The level of agreement of the CARE scoring between the three physicians was then assessed.

Results

The calibration analysis revealed no significant difference between expected and observed outcomes for the three classifications. The areas under the receiver operating characteristic curves for mortality were 0.77 with the CARE score, 0.78 with the EuroSCORE, and 0.73 with the Tu score (not significant). The agreement rate of the CARE scoring between two anesthesiologists, between anesthesiologists and surgeons, and between anesthesiologists and cardiologists were 90%, 83%, and 77%, respectively.

Conclusions

Despite its simplicity, the CARE score predicts mortality and major morbidity as well the EuroSCORE. In addition, it remains devoid of significant variability when used by groups of physicians of different specialties.
Recovery from Sleep Deprivation Occurs during Propofol Anesthesia
Authors: Tung Avery , Bergmann Bernard M. , Herrera Stacy , Cao Dingcai , Mendelson Wallace B.
Published: May 2004

Background

Some neurophysiologic similarities between sleep and anesthesia suggest that an anesthetized state may reverse effects of sleep deprivation. The effect of anesthesia on sleep homeostasis, however, is unknown. To test the hypothesis that recovery from sleep deprivation occurs during anesthesia, the authors followed 24 h of sleep deprivation in the rat with a 6-h period of either ad libitum sleep or propofol anesthesia, and compared subsequent sleep characteristics.

Methods

With animal care committee approval, electroencephalographic/electromyographic electrodes and intrajugular cannulae were implanted in 32 rats. After a 7-day recovery and 24-h baseline electroencephalographic/electromyographic recording period, rats were sleep deprived for 24 h by the disk-over-water method. Rats then underwent 6 h of either propofol anesthesia (n = 16) or ad libitum sleep with intralipid administration (n = 16), followed by electroencephalographic/electromyographic monitoring for 72 h.

Results

In control rats, increases above baseline in non-rapid eye movement sleep, rapid eye movement sleep, and non-rapid eye movement delta power persisted for 12 h after 24 h of sleep deprivation. Recovery from sleep deprivation in anesthetized rats was similar in timing to that of controls. No delayed rebound effects were observed in either group for 72 h after deprivation.

Conclusion

These data show that a recovery process similar to that occurring during naturally occurring sleep also takes place during anesthesia and suggest that sleep and anesthesia share common regulatory mechanisms. Such interactions between sleep and anesthesia may allow anesthesiologists to better understand a potentially important source of variability in anesthetic action and raise the possibility that anesthetics may facilitate sleep in environments where sleep deprivation is common.
γ-Aminobutyric Acid Type A Receptor β2 Subunit Mediates the Hypothermic Effect of Etomidate in Mice
Authors: Cirone Jennifer , Rosahl Thomas W. , Reynolds David S. , Newman Richard J. , O'Meara Gillian F. , Hutson Peter H. , Wafford Keith A.
Published: May 2004

Background

The authors have previously described that the gamma-aminobutyric acid type A (GABAA) receptor beta 2N265S mutation results in a knock-in mouse with reduced sensitivity to etomidate. After recovery from etomidate anesthesia, these mice have improved motor performance and less slow wave sleep. Because most clinically used anesthetics produce hypothermia, the effect of this mutation on core body temperature was investigated.

Methods

The effect of etomidate and propofol on core body temperature were measured using radiotelemetry in freely moving GABAA receptor beta 2N265S mutant mice and wild-type controls.

Results

beta 2N265S mutant mice have a reduced hypothermic response to anesthetic doses of etomidate compared with wild-type controls and after a transient loss of righting reflex regain normothermia more rapidly compared with wild-type controls. Subanesthetic doses of etomidate produce hypothermia, which was not observed in the mutant mice. Vehicle administration resulted in a stress-induced hyperthermic response in both genotypes. Propofol produced a hypothermic response that was similar in both genotypes.

Conclusions

The GABAA receptor beta 2 subunit mediates a significant proportion of the hypothermic effects of etomidate. As the beta 2 subunit mediates postrecovery ataxia and sedation, anesthetic agents that do not have in vivo potency at beta 2 subunit-containing receptors offer the potential for surgical anesthesia with improved recovery characteristics.
Endotracheal Tubes Coated with Antiseptics Decrease Bacterial Colonization of the Ventilator Circuits, Lungs, and Endotracheal Tube
Authors: Berra Lorenzo , De Marchi Lorenzo , Yu Zu-Xi , Laquerriere Patrice , Baccarelli Andrea , Kolobow Theodor
Published: May 2004

Background

Formation of a bacterial biofilm within the endotracheal tube (ETT) after tracheal intubation is rapid and represents a ready source of lung bacterial colonization. The authors investigated bacterial colonization of the ventilator circuit, the ETT, and the lungs when the ETT was coated with silver-sulfadiazine and chlorhexidine in polyurethane, using no bacterial/viral filter attached to the ETT.

Methods

Sixteen sheep were randomized into two groups. Eight sheep were intubated with a standard ETT (control group), and eight were intubated with a coated ETT (study group). Animals were mechanically ventilated for 24 h. At autopsy, the authors sampled the trachea, bronchi, lobar parenchyma, and ETT for quantitative bacterial cultures. Qualitative bacterial cultures were obtained from the filter, humidifier, inspiratory and expiratory lines, and water trap. ETTs were analyzed with light microscopy, scanning electron microscopy, and laser scanning confocal microscopy.

Results

In the control group, all eight ETTs were heavily colonized (10(5)-10(8) colony-forming units [cfu]/g), forming a thick biofilm. The ventilator circuit was always colonized. Pathogenic bacteria colonized the trachea and the lungs in five of eight sheep (up to 10(9) cfu/g). In the study group, seven of eight ETTs and their ventilator circuits showed no growth, with absence of a biofilm; one ETT and the respective ventilator circuit showed low bacterial growth (10(3)-10(4) cfu/g). The trachea was colonized in three sheep, although lungs and bronchi showed no bacterial growth, except for one bronchus in one sheep.

Conclusions

Coated ETTs induced a nonsignificant reduction of the tracheal colonization, eliminated (seven of eight) or reduced (one of eight) bacterial colonization of the ETT and ventilator circuits, and prevented lung bacterial colonization.
Recombinant Human Hemoglobin with Reduced Nitric Oxide–scavenging Capacity Restores Effectively Pancreatic Microcirculatory Disorders in Hemorrhagic Shock
Authors: von Dobschuetz Ernst , Hutter Joerg , Hoffmann Tomas , Messmer Konrad
Published: May 2004

Background

Scavenging of nitric oxide by hemoglobin-based oxygen carriers could aggravate microcirculatory failure in splanchnic organs after hemorrhagic shock as a consequence of vasoconstrictive side effects. The aim of this study was to compare the effects of two recombinant human hemoglobin solutions, a second-generation product bearing reduced nitric oxide-scavenging properties (rHb2.0) due to site directed mutagenesis of the heme pocket and a first-generation recombinant hemoglobin (rHb1.1) with scavenging capacity similar to native hemoglobin, on the pancreatic microcirculation after hemorrhagic shock.

Methods

Twenty-eight pentobarbital-anesthetized rats were bled to a mean arterial pressure of 40 mmHg and maintained at this level for 1 h. Using an intravital microscope, the length of erythrocyte-perfused pancreatic capillaries per observation area (functional capillary density) were measured in animals resuscitated by volumes of hydroxyethyl starch, rHb1.1, or rHb2.0 equivalent to the shed blood volume. Animals without shock induction served as control.

Results

As compared with control (438 +/- 10 cm(-1)), animals treated with hydroxyethyl starch (315 +/- 44 cm(-1)) and rHb1.1 (288 +/- 67 cm(-1)) showed a significant reduction of functional capillary density after 2 h of resuscitation. rHb2.0 was able to restore functional capillary density (410 +/- 42 cm(-1)) and mean arterial pressure to baseline values.

Conclusion

rHb2.0 was effectively able to restore pancreatic microcirculation after hemorrhagic shock. This may be related to the compound's effective lack of nitric oxide-scavenging properties. This hemoglobin solution or ones similar to it might be uniquely valuable for resuscitation from hemorrhagic shock.
Replacement of proline with valine does not remove an apparent proline isomerization‐dependent folding event in CRABP I
Authors: Burns‐Hamuro Lora L. , Dalessio Paula M. , Ropson Ira J.
Published: May 2004

Site‐directed mutagenesis has frequently been used to replace proline with other amino acids in order to determine if proline isomerization is responsible for a slow phase during refolding. Replacement of Pro 85 with alanine in cellular retinoic acid binding protein I (CRABP‐I) abolished the slowest refolding phase, suggesting that this phase is due to proline isomerization in the unfolded state. To further test this assumption, we mutated Pro 85 to valine, which is the conservative replacement in the two most closely related proteins in the family (cellular retinoic acid binding protein II and cellular retinol binding protein I). The mutant protein was about 1 kcal/mole more stable than wild type. Retinoic acid bound equally well to wild type and P85V‐CRABP I, confirming the functional integrity of this mutation. The refolding and unfolding kinetics of the wild‐type and mutant proteins were characterized by stopped flow fluorescence and circular dichroism. The mutant P85V protein refolded with three kinetic transitions, the same number as wild‐type protein. This result conflicts with the P85A mutant, which lost the slowest refolding rate. The P85V mutation also lacked a kinetic unfolding intermediate found for wild‐type protein. These data suggest that proline isomerization may not be responsible for the slowest folding phase of CRABP I. As such, the loss of a slow refolding phase upon mutation of a proline residue may not be diagnostic for proline isomerization effects on protein folding.
Some fundamental aspects of building protein structures from fragment libraries
Authors: Holmes J. Bradley , Tsai Jerry
Published: May 2004

We have investigated some of the basic principles that influence generation of protein structures using a fragment‐based, random insertion method. We tested buildup methods and fragment library quality for accuracy in constructing a set of known structures. The parameters most influential in the construction procedure are bond and torsion angles with minor inaccuracies in bond angles alone causing >6 Å CαRMSD for a 150‐residue protein. Idealization to a standard set of values corrects this problem, but changes the torsion angles and does not work for every structure. Alternatively, we found using Cartesian coordinates instead of torsion angles did not reduce performance and can potentially increase speed and accuracy. Under conditions simulating ab initio structure prediction, fragment library quality can be suboptimal and still produce near‐native structures. Using various clustering criteria, we created a number of libraries and used them to predict a set of native structures based on nonnative fragments. Local CαRMSD fit of fragments, library size, and takeoff/landing angle criteria weakly influence the accuracy of the models. Based on a fragment's minimal perturbation upon insertion into a known structure, a seminative fragment library was created that produced more accurate structures with fragments that were less similar to native fragments than the other sets. These results suggest that fragments need only contain native‐like subsections, which when correctly overlapped, can recreate a native‐like model. For fragment‐based, random insertion methods used in protein structure prediction and design, our findings help to define the parameters this method needs to generate near‐native structures.
The ternary complex of Pseudomonas aeruginosa alcohol dehydrogenase with NADH and ethylene glycol
Authors: Levin Inna , Meiri Gal , Peretz Moshe , Burstein Yigal , Frolow Felix
Published: May 2004

Pseudomonas aeruginosa alcohol dehydrogenase (PaADH; ADH, EC 1.1.1.1) catalyzes the reversible oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones, using NAD as coenzyme. We crystallized the ternary complex of PaADH with its coenzyme and a substrate molecule and determined its structure at a resolution of 2.3 Å, using the molecular replacement method. The PaADH tetramer comprises four identical chains of 342 amino acid residues each and obeys ∼222‐point symmetry. The PaADH monomer is structurally similar to alcohol dehydrogenase monomers from vertebrates, archaea, and bacteria. The stabilization of the ternary complex of PaADH, the coenzyme, and the poor substrate ethylene glycol (kcat = 4.5 sec−1; Km > 200 mM) was due to the blocked exit of the coenzyme in the crystalline state, combined with a high (2.5 M) concentration of the substrate. The structure of the ternary complex presents the precise geometry of the Zn coordination complex, the proton‐shuttling system, and the hydride transfer path. The ternary complex structure also suggests that the low efficiency of ethylene glycol as a substrate results from the presence of a second hydroxyl group in this molecule.
Understanding Successful and Unsuccessful EFL Students in Chinese Universities
Authors: Gan Zhengdong , Humphreys Gillian , Hamp‐Lyons Liz
Published: May 2004

Unlike success in first language acquisition, success in learning a second or foreign language is considerably more variable. Recently, second language acquisition researchers have called for more integrative research on individual difference factors. With this goal in mind, this study followed a larger, quantitative study of the links between self‐directedness for language learning and English language learning attainment among university students on the Chinese mainland and in Hong Kong. Drawing on the findings of that study (Gan, 2003), this 1‐semester study looked closely at 2 small groups of tertiary‐level English as a foreign language (EFL) learners in China in order to document how they carried out their out‐of‐class (self‐directed) English learning, as well as to elaborate issues that may be critical to understanding the variability that had already been observed in their English learning outcomes.

The data were gathered through interviews, diaries, and follow‐up email correspondence with 9 successful and 9 unsuccessful second‐year EFL students at 2 Chinese mainland universities. Using grounded theory methodology (Strauss & Corbin, 1994, 1998), 6 categories of qualitative data were constructed: conceptualizing English language learning; perceptions of the College English Course; learning and practising strategies; self‐management; internal drive; and English proficiency tests. The study findings suggest that different levels of success may be explained by a complex and dynamic interplay of internal cognition and emotion, external incentives, and social context. The findings imply the need to take a holistic view of variation in language learning outcomes and to broaden the scope of the current practice in learner strategy training.
Symposium on Implementing Public Policy: Learning from Theory and Practice
Authors: Schofield Jill , Sausman Charlotte
Published: May 2004

The initiative for this symposium issue arose out of a series of five ESRC seminars called ‘Implementing Public Policy: Learning from Each Other’. The aim of the seminars was to revitalize interest amongst public policy researchers about implementation studies, to advance the development of ideas about public policy implementation and to assess the relevance of academic models of public policy implementation to those who deliver public services.
Big Windows and Little Windows: Implementation in the ‘Congested State’
Authors: Exworthy Mark , Powell Martin
Published: May 2004

This paper argues for the need to re‐assess models of policy implementation in the ‘congested state’. This re‐appraisal focuses on two main directions. The first involves locating implementation in the context of wider models of the policy process. We fuse three models, those of Kingdon, Wolman, and Challis et al., to form a new ‘policy streams’ approach. The second examines implementation in multi‐level governance. In the UK and elsewhere, much of the focus of traditional implementation studies has been on the link between one central government department and a local agency. However, this vertical (central‐local) dimension fails to give sufficient stress to the other horizontal dimensions of ‘central‐central’ and ‘local‐local’. Paraphrasing Kingdon's terms, implementation models also need to incorporate the ‘little windows’ at local level as well as the ‘big’ windows at national level. Using evidence relating to the implementation of UK policy towards health inequalities, this paper argues successful implementation is more likely when the three policy streams are linked across the three dimensions. The model is thought to be applicable to other areas of the public sectors and complex issues facing all governments.
Freedom to do What you are Told: Senior Management Team Autonomy in an NHS Acute Trust
Authors: Hoque Kim , Davis Simon , Humphreys Michael
Published: May 2004

Arguably, the government's aim of using the reward of ‘earned autonomy’ and Foundation Trust status as an incentive to improve performance in the NHS will only be effective if Trust managers view greater autonomy as both desirable and realistic. This article examines this issue by investigating the extent to which members of an NHS Trust's senior management team perceive themselves as autonomous, the factors most likely to hinder their ability to operate autonomously, and the extent to which managers want greater autonomy. In the event, autonomy was largely restricted by extensive centrally dictated targets. Entrenched professional interests and a lack of managerial skills on the part of clinician managers suggested limitations on the extent to which autonomy can be realistically devolved. Additionally, there was little belief among managers that greater autonomy would enable healthcare services to be delivered more effectively.
The Institutional Context of Market Ideology: A Comparative Analysis of the Values and Perceptions of Local Government CEOs in 14 OECD Countries
Authors: Hansen Morten Balle , Lauridsen Jørgen
Published: May 2004

During recent decades, various versions of market practices have, in most nation states, diffused into the public sector. We analyse variations in the adoption of market ideologies and examine plausible explanations for these variations. Four managerial ideal types are constructed, based on their attitudes towards two dimensions of market ideology. Managerial attitudes and perceptions are conceived as embedded in a global process of diffusion highly affected by varying institutional preconditions. The impact of five types of institutional contexts is examined: the national context, the organizational context, the context of interaction, the context of socialization and the norms of the manager.
Analysis of determinants of mammalian species richness in South America using spatial autoregressive models
Authors: Tognelli Marcelo F. , Kelt Douglas A.
Published: May 2004

Classically, hypotheses concerning the distribution of species have been explored by evaluating the relationship between species richness and environmental variables using ordinary least squares (OLS) regression. However, environmental and ecological data generally show spatial autocorrelation, thus violating the assumption of independently distributed errors. When spatial autocorrelation exists, an alternative is to use autoregressive models that assume spatially autocorrelated errors. We examined the relationship between mammalian species richness in South America and environmental variables, thereby evaluating the relative importance of four competing hypotheses to explain mammalian species richness. Additionally, we compared the results of ordinary least squares (OLS) regression and spatial autoregressive models using Conditional and Simultaneous Autoregressive (CAR and SAR, respectively) models. Variables associated with productivity were the most important at determining mammalian species richness at the scale analyzed. Whereas OLS residuals between species richness and environmental variables were strongly autocorrelated, those from autoregressive models showed less spatial autocorrelation, particularly the SAR model, indicating its suitability for these data. Autoregressive models also fit the data better than the OLS model (increasing R2by 5–14%), and the relative importance of the explanatory variables shifted under CAR and SAR models. These analyses underscore the importance of controlling for spatial autocorrelation in biogeographical studies.
Presence‐absence versus presence‐only modelling methods for predicting bird habitat suitability
Authors: Brotons Lluís , Thuiller Wilfried , Araújo Miguel B. , Hirzel Alexandre H.
Published: May 2004

Habitat suitability models can be generated using methods requiring information on species presence or species presence and absence. Knowledge of the predictive performance of such methods becomes a critical issue to establish their optimal scope of application for mapping current species distributions under different constraints. Here, we use breeding bird atlas data in Catalonia as a working example and attempt to analyse the relative performance of two methods: the Ecological Niche factor Analysis (ENFA) using presence data only and Generalised Linear Models (GLM) using presence/absence data. Models were run on a set of forest species with similar habitat requirements, but with varying occurrence rates (prevalence) and niche positions (marginality). Our results support the idea that GLM predictions are more accurate than those obtained with ENFA. This was particularly true when species were using available habitats proportionally to their suitability, making absence data reliable and useful to enhance model calibration. Species marginality in niche space was also correlated to predictive accuracy, i.e. species with less restricted ecological requirements were modelled less accurately than species with more restricted requirements. This pattern was irrespective of the method employed. Models for wide‐ranging and tolerant species were more sensitive to absence data, suggesting that presence/absence methods may be particularly important for predicting distributions of this type of species. We conclude that modellers should consider that species ecological characteristics are critical in determining the accuracy of models and that it is difficult to predict generalist species distributions accurately and this is independent of the method used. Being based on distinct approaches regarding adjustment to data and data quality, habitat distribution modelling methods cover different application areas, making it difficult to identify one that should be universally applicable. Our results suggest however, that if absence data is available, methods using this information should be preferably used in most situations.
Shallow males, deep females: sex‐biased differences in habitat distribution of the freshwater calanoid copepod Arctodiaptomus alpinus
Authors: Schabetsberger Robert , Jersabek Christian D.
Published: May 2004

In a small, circular high‐altitude karst lake situated in the northeastern calcareous Alps of Austria the copepod Arctodiaptomus alpinus (Imhof) develops each spring from resting eggs after the lake basin fills in early spring. After mid‐summer, late developmental stages and adults concentrate in a thin layer near the sediment throughout the lake basin. During daytime an average 86% and 71% of female and male copepods respectively resided near the bottom. Males exhibited stronger diel vertical migrations than females and part of the population concentrated in near‐surface water at night, but the majority of copepods remained at the sediment during darkness. Macro‐photographs and core samples revealed that the proportion of epibenthic male A. alpinus decreased constantly from >70% in 3 m depth to <20% below the 8‐m isobath. The proportion of ovigerous females increased with depth, whereas non‐ovigerous females were comparatively more abundant in shallow water. Concurrently the highest frequencies of copulating copepods were detected in areas of high male density. Above the 3‐m isobath male A. alpinus formed dense swarms in scattered patches of the macrophyte Ranunculus eradicatus (>93% males; maximum abundance: 362 600 individuals m−2). Adults and larvae of the alpine newt Triturus alpestris are the top predators in this fishless alpine lake, and A. alpinus constitutes a major component of their diet. However, predator densities and different predation rates on male and female copepods were not sufficient to explain the observed horizontal distribution of A. alpinus. We argue that the optimization of successful sexual encounters in copepods is the ultimate driving force behind this segregation of both sexes of A. alpinus (‘mate encounter hypothesis’).