bluuebunny/crossref_metadata_2025 huggingface dataset:
Model‐error estimation in 4D‐Var
Authors: Trémolet Yannick
Published: July 2007

Current operational implementations of 4D‐Var rely on the assumption that the numerical model representing the evolution of the atmospheric flow is perfect, or at least that model errors are small enough (relative to other errors in the system) to be neglected. This paper describes a formulation of weak‐constraint 4D‐Var that removes that assumption by explicitly representing model error as part of the 4D‐Var control variable.

The consequences of this choice of control variable for the implementation of incremental 4D‐Var are discussed. It is shown that the background‐error covariance matrix cannot be used as an approximate model‐error covariance matrix. Another model‐error covariance matrix, based on statistics of model tendencies, is proposed.

Experimental results are presented. They show that this approach to accounting for and estimating model error captures some known model errors and improves the fit to observations, both in the analysis and in the background, but that it also captures part of the observation bias. We show that the model error estimated in this approach varies rapidly, and cannot be used to correct medium‐ or long‐range forecasts. We also show that, because it relies on the tangent linear assumption for the entire assimilation window, the incremental formulation of weak‐constraint 4D‐Var is not the most suitable formulation for long assimilation windows. Copyright © 2007 Royal Meteorological Society
Adaptive ensemble reduction and inflation
Authors: Uzunoglu B. , Fletcher S. J. , Zupanski M. , Navon I. M.
Published: July 2007

In this paper we address the question of whether it is possible consistently to reduce the number of ensemble members at a late stage in the assimilation cycle. As an extension, we consider the question: given this reduction, is it possible to reintroduce ensemble members at a later time, if the accuracy is decreasing significantly? To address these questions, we present an adaptive methodology for reducing and inflating an ensemble by projecting the ensemble onto a limited number of its leading empirical orthogonal functions, through a proper orthogonal decomposition. We then apply this methodology with a global shallow‐water‐equations model on the sphere in conjunction with an ensemble filter developed at Florida State University and the Cooperative Institute for Research in the Atmosphere at Colorado State University. An adaptive methodology for reducing and inflating ensembles is successfully applied in two contrasting test cases with the shallow‐water‐equations model. It typically results in a reduction in the number of ensemble members required for successful implementation, by a factor of up to two. Copyright © 2007 Royal Meteorological Society
Performance of the ECMWF forecasting system in the Arctic during winter
Authors: Jung Thomas , Leutbecher Martin
Published: July 2007

The performance of the ECMWF forecasting system in the Arctic during boreal winter is investigated. A comparison between different analysis products suggests that synoptic‐scale features in the Arctic are relatively well represented by state‐of‐the‐art analysis systems. Furthermore, it is shown that the improvement in deterministic forecast error in the Arctic since the early 1980s closely follows that reported in previous studies for the Northern Hemisphere as a whole. One of the biggest ‘jumps’ in deterministic forecast skill, both in the troposphere and in the stratosphere, occurred in autumn 2000 when the high‐resolution deterministic system (TL511, about 40 km) was introduced at ECMWF. Our results suggest that 10‐day forecasts of the stratospheric circulation have been very skilful, particularly since the introduction of the high‐resolution system. Adjoint computations reveal pronounced flow‐dependence of the sensitivity of short‐range forecast error to initial perturbations at high northern latitudes (north of 70°N); this highlights the importance of using ensemble prediction systems (EPSs) for weather forecasting in the Arctic. Verification of the ECMWF EPS in the Arctic reveals substantial improvements in probabilistic predictive skill since the mid‐1990s. The most pronounced increase in probabilistic forecast skill, particularly on synoptic scales, occurred in autumn 2000 when the high‐resolution EPS (TL255, about 80 km) was introduced. Finally, it is shown that the observed stratosphere–troposphere link (‘downward propagation’ of stratospheric anomalies), which constitutes a potential source of extended‐range predictability in high latitudes, is realistically represented in seasonal integrations with the ECMWF model—even at the relatively low horizontal resolution of TL95 (about 180 km). Copyright © 2007 Royal Meteorological Society
Combining agile software projects and large‐scale organizational agility
Authors: Kettunen Petri , Laanti Maarit
Published: July 2007

Nowadays many new product development (NPD) software projects employ agile methodologies. Their basic premise is that a small, colocated team working closely together with the business customer can produce high‐value, high‐quality software efficiently with rapid iterations and frequent feedback. However, in large NPD organizations developing complex products those basic assumptions are not necessarily sufficient, and a more comprehensive view of agility is needed. On the basis of industrial experiences, this article presents a number of pragmatic suggestions about how and when agility could be utilized in large‐scale (embedded) software product development. We propose a framework for understanding the multidimensional nature of agility in such environments for successful software process improvement (SPI), and highlight certain practical considerations. Some industrial case examples are illustrated. We conclude that in large‐scale NPD organizations a holistic systemwide view is needed in order to really be able to take advantage of and improve software development agility. Copyright © 2007 John Wiley & Sons, Ltd.
The prognostic influence of chronic obstructive pulmonary disease in patients hospitalised for chronic heart failure
Authors: Macchia Alejandro , Monte Simona , Romero Marilena , D'Ettorre Antonio , Tognoni Gianni
Published: July 2007

Aims:

To investigate the prevalence and the prognostic impact of chronic obstructive pulmonary disease (COPD), in patients hospitalised with chronic heart failure (CHF).

Methods and results:

In an observational study based on longitudinal information from administrative registers, 1020 patients aged ≥60 years, who were chronically treated for and hospitalised with CHF were identified and followed‐up for major events up to 1 year.

Median age was 80 years, half of the patients were female and 241 patients (23.6%) had concomitant COPD. There were no differences in the prevalence of cardiovascular and non‐cardiovascular comorbidities between CHF patients with or without COPD. However, COPD patients were more often male (60.6% vs. 46.3%), more frequently treated with diuretics (95.9% vs. 91.5%) but less often exposed to β‐blockers (16.2% vs. 22.0%). Significantly higher adjusted in‐hospital (HR 1.50 [95%CI 1.00–2.26]) and out‐of‐hospital (1.42 [1.09–1.86]) mortality rates were found in CHF patients with concomitant COPD. A higher occurrence of non‐fatal AMI/stroke/rehospitalisation for CHF (1.26 [1.01–1.58]) as well as hospitalisation for CHF (1.35 [1.00–1.82]) was associated with COPD.

Conclusions:

COPD is a frequent concomitant disease in patients with heart failure and it is an independent short‐term prognostic indicator of mortality and cardiovascular comorbidity in patients who have been admitted to hospital for heart failure.
Laparoscopic entry techniques and complications
Authors: Ahmad G. , Duffy J.M.N. , Watson A.J.S.
Published: July 2007

Objective: To identify laparoscopic entry techniques employed by gynecologists in the United Kingdom to determine if the consensus technique is adhered to, and to observe whether entry technique affects complication rate. Method: An anonymous postal questionnaire was sent to gynecologists with an interest in laparoscopic surgery in the United Kingdom. Results: At total of 568 questionnaires were sent and 345 (60.7%) were returned. Of gynecologists who returned the questionnaire 194 (57%) reported occurrence of a major bowel or vascular complication. In terms of the key elements of the consensus document there was no significant difference in entry technique used between those that reported major injury (vascular, bowel, or both), and those that did not. Conclusions: This survey demonstrates the variation in entry techniques used by gynecologists in the United Kingdom. Without a good evidence‐base to the contrary no entry technique can be stated as safer than another.
Creating consumer durable retailer customer loyalty through order fulfillment service operations
Authors: Davis‐Sramek Beth , Mentzer John T. , Stank Theodore P.
Published: July 2007

Manufacturers now find themselves in the position of finding new ways to remain competitive in the era of retail power. The onus rests on the manufacturer's ability to implement operational strategies that help the retailer achieve its objectives. Specifically, manufacturers that establish successful order fulfillment service can affect retailer loyalty. The overarching goal of this research, therefore, is to examine the importance to operations managers of understanding the order fulfillment needs and expectations of their retail customers and to establish the value‐added role that operations management plays in developing retailer loyalty. Empirical evidence is provided on the relationships between relational order fulfillment service, operational order fulfillment service, satisfaction, affective commitment, purchase behavior, and loyalty. Such evidence not only focuses on the strategic importance of the OM discipline in manufacturer–retailer relationships, but also extends previous OM theory by taking a more complex view of the loyalty phenomenon.
Detection of hot event in the equatorial Indo‐Pacific warm pool using advanced satellite sea surface temperature, solar radiation, and wind speed
Authors: Qin Huiling , Kawamura Hiroshi , Kawai Yoshimi
Published: July 2007

Using advance satellite‐derived sea surface temperature (SST), solar radiation and wind speed products, we investigate hot events (HEs) associated with very high SST of around 30°C. Amplitude of the SST diurnal variation (DSST) is obtained by an empirical formula with the downward surface shortwave radiation (DSSR) and the wind speed. The HE is defined as a connected region with SST > the time‐dependent SST threshold of about 30°C having a minimum areal size greater than 3 × 106 km2 and lasting for a period longer than 10 days. Thirty‐one hot events were detected from 1993 to 2003 in and around the equatorial Indo‐Pacific warm pool. The HE precursor is increase of an area with SST > the time‐dependent SST threshold, and the HE starts when the areal size exceeds the areal threshold. It keeps the very high SST for a while, and then its SST decreases with decrease of the HE area toward its ending phase. The HE area and the high‐DSST area correspond with each other on timescales of daily and the whole one event period. In the HE period, a clear‐sky and low‐wind condition becomes the reason for large DSST appearance. Through statistics of the detected 31 HEs, it is indicated that the mean HE period, the mean areal size, and the means of the regional HE areal averaged SST are 24.2 days, 1.57 × 107 km2, and 0.25°C above the time‐dependent SST threshold, respectively. The HE area shifts with season though they stay within/around the SST contour of 28°C in the Indo‐Pacific oceans.
Phytoplankton scales of variability in the California Current System: 1. Interannual and cross‐shelf variability
Authors: Henson Stephanie A. , Thomas Andrew C.
Published: July 2007

In the California Current System, strong mesoscale variability associated with eddies and meanders of the coastal jet play an important role in the biological productivity of the area. To assess the dominant timescales of variability, a wavelet analysis is applied to almost nine years (October 1997 to July 2006) of 1‐km‐resolution, 5‐day‐averaged, Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) chlorophyll a (chl a) concentration data. The dominant periods of chlorophyll variance, and how these change in time, are quantified as a function of distance offshore. The maximum variance in chlorophyll occurs with a period of ∼100–200 days. A seasonal cycle in the timing of peak variance is revealed, with maxima in spring/summer close to shore (20 km) and in autumn/winter 200 km offshore. Interannual variability in the magnitude of chlorophyll variance shows maxima in 1999, 2001, 2002, and 2005. There is a very strong out‐of‐phase correspondence between the time series of chlorophyll variance and the Pacific Decadal Oscillation (PDO) index. We hypothesize that positive PDO conditions, which reflect weak winds and poor upwelling conditions, result in reduced mesoscale variability in the coastal region, and a subsequent decrease in chlorophyll variance. Although the chlorophyll variance responds to basin‐scale forcing, chlorophyll biomass does not necessarily correspond to the phase of the PDO, suggesting that it is influenced more by local‐scale processes. The mesoscale variability in the system may be as important as the chl a biomass in determining the potential productivity of higher trophic levels.
Phytoplankton scales of variability in the California Current System: 2. Latitudinal variability
Authors: Henson Stephanie A. , Thomas Andrew C.
Published: July 2007

The California Current System encompasses a southward flowing current which is perturbed by ubiquitous mesoscale variability. The extent to which latitudinal patterns of physical variability are reflected in the distribution of biological parameters is poorly known. To investigate the latitudinal distribution of chlorophyll variance, a wavelet analysis is applied to nearly 9 years (October 1997 to July 2006) of 1‐km‐resolution Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) chlorophyll concentration data at 5‐day resolution. Peaks in the latitudinal distribution of chlorophyll variance coincide with features of the coastal topography. Maxima in variance are located offshore of Vancouver Island and downstream of Heceta Bank, Cape Blanco, Point Arena, and possibly Point Conception. An analysis of dominant wavelengths in the chlorophyll data reveals a transfer of energy into smaller scales is generated in the vicinity of the coastal capes. The latitudinal distribution of variance in sea level anomaly corresponds closely to the chlorophyll variance in the nearshore region (<100 km offshore), suggesting that the same processes determine the distribution of both. Farther offshore, there is no correspondence between latitudinal patterns of sea level anomaly and chlorophyll variance. This likely represents a transition from physical to biological control of the phytoplankton distribution.
Antarctic deglacial pattern in a 30 kyr record of sea surface temperature offshore South Australia
Authors: Calvo Eva , Pelejero Carles , De Deckker Patrick , Logan Graham A.
Published: July 2007

Comparison of ice cores from Greenland and Antarctica shows an asynchronous two‐step warming at these high latitudes during the Last Termination. However, the question whether this asynchrony extends to lower latitudes is unclear mainly due to the scarcity of paleorecords from the Southern Hemisphere. New data from a marine core collected off South Australia (∼36°S) allows a detailed reconstruction of sea‐surface temperatures over the Last Termination. This confirms the existence of an Antarctic‐type deglacial pattern and shows no indication of cooling associated with the Northern Hemisphere YD event. The SST record also provides a new comparison with the more extensive paleoclimatic data available from continental Australia. This shows a strong climatic link between onshore and offshore records for Australia and to Southern Hemisphere paleorecords. We also show a progressive SST drop over the last ∼6.5 kyr not seen before for the Australian region.
Nighttime ionospheric D region parameters from VLF phase and amplitude
Authors: Thomson Neil R. , Clilverd Mark A. , McRae Wayne M.
Published: July 2007

Nighttime ionospheric D region heights and electron densities are determined from an extensive set of VLF radio phase and amplitude observations. The D region parameters are characterized by the traditional H′ (height in kilometers) and β (sharpness in km−1) as used by Wait and by the U. S. Navy in their Earth‐ionosphere waveguide programs. The VLF measurements were made with several frequencies in the range 10 kHz to 41 kHz on long, mainly all‐sea paths, including Omega La Reunion and Omega Argentina to Dunedin, New Zealand, NAU (Puerto Rico) and NAA (Maine, USA) to Cambridge, UK, and NPM (Hawaii) to San Francisco. Because daytime VLF propagation on such paths is readily measured and predicted, the differences between night and day amplitudes and phases were measured and compared with calculations for a range of nighttime ionospheric parameters. This avoided the problem of uncertainties in the transmitter powers. In this way the height, H′, and the sharpness, β, when averaged over periods of several days, at least for the midlatitude D region near solar minimum, were found to be 85.1 ± 0.4 km and 0.63 ± 0.04 km−1, respectively.
Comment on “Ion collection by a sphere in a flowing collisional plasma” [Phys. Plasmas 14, 034502 (2007)]
Authors: Hutchinson I. H.
Published: July 2007

It is shown that the numerical solutions presented in a recent paper discussing a highly simplified model of collisional particle collection are unnecessary because simple analytic solutions of the quantities presented are available.
Nonlinear instability of a thin film flowing down a smoothly deformed surface
Authors: Dávalos-Orozco L. A.
Published: July 2007

Here, the nonlinear flow instability of a thin film flowing down an inclined wall with smooth deformations is investigated. A nonlinear evolution equation is obtained under the small wavenumber approximation. This equation describes the film free surface deformation including the effects of inertia, viscosity, surface tension, and deformation of the wall. The equation has a forcing term that corresponds to periodic time-dependent perturbations hitting on the free surface. These time-dependent perturbations are tested against the presence of the free surface waves due to wall deformations. In particular, a wall sinusoidal profile is investigated. It is found that when the wall wavelength is small enough, the valleys of the surface response to the wall profile become very deep, showing a kind of resonance, which has an important stabilizing influence in the evolution of the superposed time-dependent perturbations.
High frequency gyrokinetic particle simulation
Authors: Kolesnikov R. A. , Lee W. W. , Qin H. , Startsev E.
Published: July 2007

The gyrokinetic approach for arbitrary frequency dynamics in magnetized plasmas is explored, using the gyrocenter-gauge kinetic theory. Contrary to low-frequency gyrokinetics, which views each particle as a rigid charged ring, arbitrary frequency response of a particle is described by a quickly changing Kruskal ring. This approach allows the separation of gyrocenter and gyrophase responses and thus allows for, in many situations, larger time steps for the gyrocenter push than for the gyrophase push. The gyrophase response which determines the shape of Kruskal rings can be described by a Fourier series in gyrophase for some problems, thus allowing control over the cyclotron harmonics at which the plasma responds. A computational algorithm for particle-in-cell simulation based on this concept has been developed. An example of the ion Bernstein wave is used to illustrate its numerical properties, and comparison with a direct Lorentz-force approach is presented.
Protocols for printing thick film ceramic libraries using the London University Search Instrument (LUSI)
Authors: Chen L. , Zhang Y. , Yang S. , Evans J. R. G.
Published: July 2007

Thick film combinatorial libraries can be prepared by mixing ceramic suspensions using stepper-driven syringes to control ink-jet-printing nozzles, but a more tolerant and efficient method has been devised using a simplification of the same equipment. By simplifying the printing sequence and using direct deposition from the stepper syringes, the time committed to a repetitive sequence of priming and cleaning the ink-jet printer nozzles is reduced. Polytetrafluoroethylene (PTFE) open ended tubes and commercial pipette tips are used as the printing nozzles. Calibration and corrections for the method are described. This method opens up the possibility for making ceramic libraries more rapidly with much simpler and less expensive equipment.
Separating species using a horizontal panel in the Scottish North Sea whitefish trawl fishery
Authors: Ferro R. S. T. , Jones E. G. , Kynoch R. J. , Fryer R. J. , Buckett B-E.
Published: July 2007

Ferro, R. S. T., Jones, E. G., Kynoch, R. J., Fryer, R. J., and Buckett, B-E. 2007. Separating species using a horizontal panel in the Scottish North Sea whitefish trawl fishery. – ICES Journal of Marine Science, 64: 1543–1550. In the North Sea, Scottish vessels target haddock, cod, whiting, monkfish, saithe, and flatfish in a mixed whitefish trawl fishery. These species mature at different sizes and hence have a range of minimum landing sizes. Their different shapes and swimming capabilities imply different selection characteristics when escaping from trawl gear. However, they are often caught at the same time on the same grounds. Optimal exploitation can only be achieved by ensuring that the selection of each species varies appropriately with length during the fishing process. This paper describes one part of a large European project to develop species-selective trawl gear to improve the exploitation pattern of North Sea cod, while maintaining the catch of other important commercial species. A gear suitable to the Scottish mixed whitefish fishery was fitted with a horizontal panel in the tapered part of the net to separate species into an upper and lower compartment. Trials were conducted on research vessels to measure separation performance for nine species in different light conditions, at different towing speeds, and with different lengths of panel. Most haddock, whiting, and saithe pass above the panel, whereas most cod, flatfish, and monkfish pass below it. Towing speed and panel length had no significant effect on separation. At lower light levels during the night (April at latitude 58° to 61°N), fewer dab, sole, plaice, and cod pass below the panel. Observations and measurements of fish behaviour using acoustic methods are described. They suggest that the height at which fish enter the net mouth may be influenced by light level and water clarity.
Behavior and Obstructive Sleep Apnea in Children: Is Obesity a Factor?
Authors: Rudnick Emily F. , Mitchell Ron B.
Published: July 2007

Objectives: Children with obstructive sleep apnea (OSA) frequently exhibit behavioral and neurocognitive problems. There is a high prevalence of OSA among obese children. This study aims to evaluate the relationship between OSA and behavioral problems in obese children as compared with normal‐weight children (controls).

Study Design: Prospective, nonrandomized, controlled study of obese and normal‐weight children with OSA presenting to a tertiary medical center for adenotonsillectomy.

Methods: All study participants underwent preoperative polysomnography to document OSA. Obesity was defined as age‐ and sex‐adjusted body mass index at the 95th percentile or higher. Behavior was evaluated using the Behavior Assessment System for Children (BASC). Preoperatively, the Behavioral Symptoms Index (BSI), a global measure of behavior, and BASC scores for obese and normal‐weight children were compared using an unpaired t test.

Results: The study population included 52 children, 18 (35%) of whom were obese. The mean age of obese children was 8.6 (range, 2.0–14.9) years. The mean age of normal‐weight children was 6.4 (range, 2.1–12.9) years. Demographics were otherwise similar. The mean apnea‐hypopnea index for obese children was 17.2 (5.0–38.0) and for normal‐weight children was 15.7 (5.3–88.0). The BSI score was 55.3 (SD, 15.9) for obese and 55.9 (SD, 15.0) for normal‐weight children. Seven (38.9%) obese and 12 (35.3%) normal‐weight children had clinically significant or abnormal behavior. Similar results were seen for the BASC scales of atypicality, depression, hyperactivity, and somatization in both groups.

Conclusions: Behavioral problems are highly prevalent in children with OSA. However, these problems exist independently of whether children are obese or normal weight.
Outcome of Endoscopic Sphenopalatine Artery Occlusion for Intractable Epistaxis: A 10‐Year Experience
Authors: Nouraei S. A. Reza , Maani Tareq , Hajioff Daniel , Saleh Hesham A. , Mackay Ian S.
Published: July 2007

Objective/Hypothesis: To evaluate the efficacy of surgical sphenopalatine artery occlusion (SAO) for treating intractable epistaxis, and identify factors associated with long‐term success or failure of this procedure.

Methods: A retrospective chart review of patients undergoing SAO surgery between January 1995 and 2005 was undertaken. Clinical and hematologic information, preoperative and surgical care, short‐term complications, and long‐term outcome were recorded. Binary logistic regression was used to identify risk factors for early re‐bleeding, and log‐rank statistics with Cox regression were used to identify risk factors for long‐term operative failure.

Results: Sixty‐seven patients underwent 71 SAO operations. The average age at surgery was 56 ± 18 years. Thirty percent of patients were being treated for hypertension, 19% were taking aspirin, and 11% were anticoagulated with warfarin. Many patients (46%) had >72 hours of epistaxis before admission, and 25% required preoperative transfusion. There were 13 (19%) bilateral procedures, six patients underwent concomitant anterior ethmoid artery occlusion, and 12 patients had concomitant septoplasty. Eight patients had significant early re‐bleeding. Platelet levels on admission and not using diathermy to occlude the sphenopalatine artery were independent risk factors for this (P values .03, and .02, respectively). Not using diathermy was also an independent risk factor for late operative failure on Cox regression, reducing the mean re‐intervention‐free interval from 94 ± 7 to 32 ± 7 months (P < .007; hazard ratio 6.4; 95% confidence interval 1.7–24.9).

Conclusions: SAO is an effective operation and, in trained hands, an appropriate first‐line procedure for treating intractable epistaxis. Use of diathermy significantly improves the short‐ and long‐term outcome of this surgery.
Smithson Tennant: meteorites and the final trip to France
Authors: Grossman Mark I
Published: July 2007

Smithson Tennant is known mainly for his discovery of osmium and iridium. This paper details Tennant's involvement with meteorites, which has received little attention by his biographers, and provides new information about his final stay in Paris. Tennant reported his analysis of the Cape of Good Hope meteorite in 1806 and received a sample of the Bendego meteorite in 1811 that was subsequently analysed by Wollaston. During Tennant's final trip to France, which began in September 1814, Berthollet presented a sample of the Limerick meteorite that he received from Tennant to the French Institute. Tennant visited Delamétherie, and an unpublished letter acquired by the author shows that he met the explorer and scientist Alexander von Humboldt. The Limerick meteorite was discussed with Delamétherie and probably with Humboldt. Evidence suggests that Tennant met the painter François Gérard and the scientists Biot, Arago, Gay-Lussac and Cuvier. The Limerick meteorite specimen that Tennant gave to Berthollet is probably Muséum National d'Histoire Naturelle sample MNHN-35, whose donor is unknown. Tennant was the first to be quoted in the scientific literature about the Limerick meteorite—more than three years before the scientist William Higgins published his account of the meteorite shower.
Learning reward expectations in honeybees
Authors: Gil Mariana , De Marco Rodrigo J. , Menzel Randolf
Published: July 2007

The aim of this study was to test whether honeybees develop reward expectations. In our experiment, bees first learned to associate colors with a sugar reward in a setting closely resembling a natural foraging situation. We then evaluated whether and how the sequence of the animals’ experiences with different reward magnitudes changed their later behavior in the absence of reinforcement and within an otherwise similar context. We found that the bees that had experienced increasing reward magnitudes during training assigned more time to flower inspection 24 and 48 h after training. Our design and behavioral measurements allowed us to uncouple the signal learning and the nutritional aspects of foraging from the effects of subjective reward values. We thus found that the animals behaved differently neither because they had more strongly associated the related predicting signals nor because they were fed more or faster. Our results document for the first time that honeybees develop long-term expectations of reward; these expectations can guide their foraging behavior after a relatively long pause and in the absence of reinforcement, and further experiments will aim toward an elucidation of the neural mechanisms involved in this form of learning.
Unresponsive asystolic cardiac arrest responding to external cardiac pacing in a patient with phaeochromocytoma
Authors: Taylor M. J. , McIndoe A.
Published: July 2007

An anaesthetised 48‐year‐old woman became haemodynamically unstable following biopsy of a thoracic mass suggesting a diagnosis of a thoracic phaeochromocytoma. Surgery was postponed to allow confirmatory investigations and pre‐operative adrenoceptor blockade with phenoxybenzamine and labetalol. Nine days later, following resection of her phaeochromocytoma, she suffered an intra‐operative asystolic cardiac arrest which was unresponsive to standard resuscitation protocols and required external cardiac pacing. We discuss the issues involved and suggest that the competitive α1 adrenoceptor antagonist doxazosin may be preferable to the covalently bound mixed alpha adrenoceptor antagonist phenoxybenzamine in the pre‐operative preparation of patients with phaeochromocytoma.
The addition of dexamethasone to dolasetron or haloperidol for treatment of established postoperative nausea and vomiting*
Authors: Rüsch D. , Arndt C. , Martin H. , Kranke P.
Published: July 2007

It is not known whether dexamethasone increases the effectiveness of anti‐emetics when given to treat postoperative nausea and vomiting (PONV). In a randomised study, 242 patients who were experiencing PONV received dolasetron and placebo, haloperidol and placebo, dolasetron and dexamethasone, or haloperidol and dexamethasone. The results from 228 patients were suitable for analysis. PONV recurred significantly less frequently in patients treated with additional dexamethasone (33%) than in patients treated without additional dexamethasone (51%). The combination of dexamethasone with dolasetron or dexamethasone with haloperidol is superior to dolasetron or haloperidol alone for the treatment of PONV.
Remote sensing‐based predictors improve distribution models of rare, early successional and broadleaf tree species in Utah
Authors: ZIMMERMANN N. E. , EDWARDS T. C. , MOISEN G. G. , FRESCINO T. S. , BLACKARD J. A.
Published: July 2007

Compared to bioclimatic variables, remote sensing predictors are rarely used for predictive species modelling. When used, the predictors represent typically habitat classifications or filters rather than gradual spectral, surface or biophysical properties. Consequently, the full potential of remotely sensed predictors for modelling the spatial distribution of species remains unexplored. Here we analysed the partial contributions of remotely sensed and climatic predictor sets to explain and predict the distribution of 19 tree species in Utah. We also tested how these partial contributions were related to characteristics such as successional types or species traits.

We developed two spatial predictor sets of remotely sensed and topo‐climatic variables to explain the distribution of tree species. We used variation partitioning techniques applied to generalized linear models to explore the combined and partial predictive powers of the two predictor sets. Non‐parametric tests were used to explore the relationships between the partial model contributions of both predictor sets and species characteristics.

More than 60% of the variation explained by the models represented contributions by one of the two partial predictor sets alone, with topo‐climatic variables outperforming the remotely sensed predictors. However, the partial models derived from only remotely sensed predictors still provided high model accuracies, indicating a significant correlation between climate and remote sensing variables. The overall accuracy of the models was high, but small sample sizes had a strong effect on cross‐validated accuracies for rare species.

Models of early successional and broadleaf species benefited significantly more from adding remotely sensed predictors than did late seral and needleleaf species. The core‐satellite species types differed significantly with respect to overall model accuracies. Models of satellite and urban species, both with low prevalence, benefited more from use of remotely sensed predictors than did the more frequent core species.

Synthesis and applications. If carefully prepared, remotely sensed variables are useful additional predictors for the spatial distribution of trees. Major improvements resulted for deciduous, early successional, satellite and rare species. The ability to improve model accuracy for species having markedly different life history strategies is a crucial step for assessing effects of global change.
An evolutionary framework for the polar regions
Authors: Crame J. A.
Published: July 2007

Abstract: Our knowledge of the nature, generation and maintenance of largescale biodiversity patterns is still far from complete. This is particularly so in the Southern Hemisphere and in the marine realm, where recent taxonomic investigations of Mollusca and other invertebrate groups has cast doubt upon the existence of a simple cline in species richness between the tropics and the pole. Comparatively high regional diversity values for the shelled gastropods and other epifaunal taxa implies a considerable evolutionary legacy; this is supported, at least in part, by available evidence from the fossil record. Certain families within the living gastropod fauna maintain their prominence when traced back 40 m.y., and perhaps even longer; in addition, several Southern Ocean gastropod and bivalve genera can now be traced back to at least the late Eocene. Use of a variety of refugia may have enabled many taxa to survive repeated glacial advances.

As we begin to revise our concept of the nature of latitudinal diversity gradients, so we also need to examine regional variations in evolutionary rates. Clearly this is a complex issue. but recourse to a pilot study based on the molluscan fossil record suggests that there may be no significant difference between the rates of radiation of tropical and cold‐temperatdpolar taxa. The most diverse clades, which are all tropical, are simply the oldest. What data are available from the fossil record indicate that there is no appreciable latitudinal variation in rates of extinction either. Time, but not necessarily environmental stability, would appear to be crucial to the development of pockets of high taxonomic diversity.

Recent improvement in our understanding of the biology of many polar marine invertebrates suggests that life in cold water is not an insuperable evolutionary problem. Of qual importance to any intrinsic properties of organisms which may have governed the differentiation of large‐scale biodiversity patterns is the role of extrinsic processes. Foremost among these has almost certainly been repeated range shifts in response to Cenozoic climatic cycles.
Fire in the tropical gallery forests of Belize
Authors: Kellman Martin , Meave Jorge
Published: July 2007

ABSTRACT. Historical records of burning, field observations, and a manipulation experiment were used to evaluate the extent and impact of fire in a system of gallery forests in the Mountain Pine Ridge savanna, Belize. The outer boundaries of gallery forests are fire‐prone zones, but fires rarely intrude into these forests. This is attributed to the existence of fire‐tolerant trees in the outer zone, which preserve a forest interior of low flammability. Occasional fire incursions are patchily distributed and partially inhibited by slope convexities. Intrusions consume litter and root mats and destroy seedlings and saplings, but create a wide variety of subsequent light regimes depending upon the degree of canopy destruction. At most sites, partial canopy cover persists and seedlings of a subset of forest tree species establish preferentially. Early survivorship of these seedlings is comparable to those established in undamaged forest. Where canopy opening is severe, a secondary succession is initiated, with large numbers of herbaceous plants deriving from the seed bank. Gallery forests contain core zones into which fire very rarely intrudes, and peripheral zones that experience fire incursions that are patchily distributed in space and time. In the latter zones fire incursions play a role comparable to that of canopy gaps in continuous forests, but also create a unique class of micro‐habitats to which a subset of tree species is specialized. The fire regime over the recent past in this gallery forest system appears to have had an enriching, rather than a depauperizing, effect on the forest communities, and such systems represent plausible refugia for forest species in fire‐prone landscapes.
Inhibiton of fatty acid biosynthesis in isolated chloroplasts by cycloxydim and other cyclohexane‐1,3‐diones
Authors: Kobek Klaus , Focke Manfred , Lichtenthaler Hartmut K. , Retzlaff Günther , Würzer Bruno
Published: July 2007

Kobek, K., Focke, M., Lichtenthaler, H.K., Retzlaff, G. and Würzer, B. 1988. Inhibiton of fatty acid biosynthesis in isolated chloroplasts by cycloxydim and other cyclohexane‐1,3‐diones. ‐ Physiol. Plant. 72: 492–498.

The effect of the three cyclohexane‐1,3‐dione herbicides cycloxydim, sethoxydim and clethodim (proposed common name) on the de novo fatty acid biosynthesis of isolated chloroplasts as test system was investigated with intact chloroplasts isolated from sensitive grasses (Poaceae) and tolerant dicotyledonous plants. All three herbicides blocked the de novo fatty acid biosynthesis ([14C]‐acetatc incorporation into total fatty acid fraction) in Avena sativa L. cv. Flämingnova chloroplasts in a dose‐dependent manner. The I50‐values are lower for cycloxydim and clethodim than for sethoxydim. The rate of de novo fatty acid biosynthesis in isolated, intact and photosynthetically active Avena chloroplasts was higher in the light than in the dark, which appeared to be due to the light‐dependent regeneration of the cofactors ATP and NADPH. The de novo fatty acid biosynthesis by isolated chloroplasts from the tolerant dicotyledonous species pea (Pisum savivum L. cv. Kleine Rheinländerin), spinach (Spinacea oleracea L. cv. Matador) and tobacco (Nicotiana tabacum L. cv. su/su) was insensitive to the three herbicides. It is assumed that one of the enzymes of the fatty acid biosynthesis is modified in the dicotyledonous plants and not accessible to the cyclohexane‐1,3‐dione herbicides. In the case of Poa annua L., which as a whole plant is tolerant towards sethoxydim, the tolerance seems not to lie in the chloroplasts but in properties of the cytoplasm, since the isolated chloroplasts are sensitive to the herbicide.
Ethylene as a possible mediator of light‐induced inhibition of root growth
Authors: Eliasson Lennart , Bollmark Marie
Published: July 2007

Eliasson, L. and Bollmark, M. 1988. Ethylene as a possible mediator of light‐induced inhibition of root growth. ‐ Physiol. Plant. 72: 605–609.

Pea seedlings (Pisum sativum L. cv. Weibull's Marma) were used to investigate the possible role of ethylene in light‐induced inhibition of root elongation. Illumination of the roots with white light inhibited root elongation by 40–50% and increased ethylene production by the roots about 4‐fold. Our main approach was to use exogenous 1‐aminocyclopropane‐1‐carboxylic acid (ACC), supplied in the growth solution, to monitor ethylene production of the roots independent of light treatment. Ethylene production of excised root tips increased with increasing ACC concentrations. The rate of ethylene production in dark‐grown roots treated with 0.1 μM ACC was similar to that caused by illumination. Low ACC concentrations (0.01–0.1 μM) decreased the rate of root elongation, especially in seedlings grown in the dark, and 0.1 μM ACC inhibited elongation to about the same extent as light. In light the roots curved and grew partly plagiogravitropically. This effect was also simulated by the 0.1 μM ACC treatment. At 1 μM and higher concentrations, ACC inhibited root growth almost completely and caused conspicuous curvatures of the root tips both in light and darkness. Inhibitors of ethylene synthesis and action partially counteracted the inhibition of root elongation caused by light. These observations suggest that the increase in ethylene production caused by light is at least partly responsible for the decreased growth of light‐exposed roots.
The influence of salinity on phosphate uptake and distribution in lupin roots
Authors: Treeby Michael T. , van Steveninck Reinhard F. M.
Published: July 2007

Treeby, M. T. and van Steveninck, R. F. M. 1988. The influence of salinity on phosphate uptake and distribution in lupin roots. ‐ Physiol. Plant. 72: 617–622.

The uptake and distribution of phosphate in lupin (Lupinus luteus L. cv. Weiko III) roots under moderate salt (NaCl) stress was studied. Vacuolar inorganic phosphate (PJ concentrations in high phosphate plants were decreased by salt, although whole root P| was unaffected. In low phosphate plants, vacuolar Pi was unaffected by salt while whole root Pi was increased. Phosphate uptake was not altered by salt in high phosphate plants, but was depressed in low phosphate plants. These observations lead to the conclusion that in high phosphate plants Pi accumulates in cytoplasm and/or stele, ultimately giving rise to phosphate toxicity in shoots. Increasing phosphate supply had no effect on Na+ accumulation in root cell vacuoles in the epidermis or cortex, but the concentration of Cl− in endodermal vacuoles was lowered.
Measurement of the activity and capacity of the alternative pathway in intact plant tissues: Identification of problems and possible solutions
Authors: Møller Ian M. , Bérczi Alajos , van der Plas Linus H. W. , Lambers Hans
Published: July 2007

Møller, I. M., Bérczi, A., van der Plas, L. H. W. and Lambers, H. 1988. Measurement of the activity and capacity of the alternative pathway in intact plant tissues: Identification of problems and possible solutions. ‐ Physiol. Plant. 72: 642–649.

The cyanide‐insensitive, benzhydroxamic acid‐sensitive (e.g. salicylhydroxamic acid, SHAM) alternative pathway is located in the inner membrane of plant mitochondria and electron flow through it is not coupled to H+ pumping and ATP synthesis. When estimating the activity and capacity of the alternative pathway in intact plant tissues three main problems arise: 1) There is almost always a substantial (10–50%) KCN‐insensitive, SHAM‐insensitive residual respiration, which may be due to peroxisomal a‐oxidation of fatty acids, and which must be subtracted from all data in the further analyses. 2) There is a (KCN‐sensitive) peroxidase in many tissues that is stimulated by low SHAM concentrations (1–10 mAf), but inhibited at higher concentrations (15–50 mM). 3) High concentrations of SHAM may inhibit the cytochrome pathway. Means of identifying and alleviating these problems are presented. Provided experimental conditions are chosen such as to minimize the three problems for each new plant organ or species or each new growth condition, SHAM can be used to estimate the size of the alternatively pathway in vivo.
Isolation of plasma membrane and binding of the Ca2+ antagonist nimodipine in Chlamydomonas reinhardtii
Authors: Dolle Reiner
Published: July 2007

Chlorophyll‐free plasma membranes of the unicellular green alga Chlamydomonas reinhardtii Dangeard were purified from a microsomal fraction using an aqueous polymer two‐phase system of 6.5% (w/w) dextran T500, 6·5% (w/w) polyethylene glycol 3350, 60 mM NaCI, 0 33 M sucrose and 5 mM potassium phosphate (pH 7·8). The plasma membrane fraction contained only 2·4% of the microsomal membrane protein. Specific activity of the plasma membrane marker enzyme, K*, Mg2+‐ATPase (EC 3.6.1.3). was enriched 9‐fold over the microsomal fraction, and 22% of total activity was recovered in the upper, polyethylene glycol‐rich phase.

Contamination from intracellular membranes was minimal. K*, Mg2+‐ATPase showed a pH optimum at about 6·5, and addition of 0·05% (w/v) Triton X‐100 stimulated the activity 3‐fold. [3H]‐Nimodipinc was employed to characterize 1,4‐dihydropyridine‐specific membrane receptors. Two apparent binding sites with different affinities to nimodipine were found in the crude microsomal fraction. The separation of plasma membranes from intracellular membranes revealed that one binding site with higher affinity (KD= 9 nM) was located on the plasma membrane and a second binding site with lower affinity (KD= 36 nM) on an intracellular membrane The apparent dissociation constants determined from the association and dissociation rate constants in kinetic experiments were comparable to those determined by equilibrium experiments. The maximum number of binding sites of the plasma membrane fraction and the intracellular membrane fraction was Bmax= 440 and 470 fmol (mg protein)‐1, respectively. [3H]‐Nimodipinc binding was inhibited by (±) verapamil and stimulated by D‐cis‐diltiazem in both fractions. Moreover, ethyle‐neglycol‐bis(2‐aminoethylcther)‐N, N'‐tetraacctic acid (EGTA) inhibited [3H]‐nimo‐dipinc binding in the plasma membrane fraction but not in the intracellular membrane fraction This effect was cancelled by the addition of CaCl2.
Related mannose‐specific lectins from different species of the family Amaryllidaceae
Authors: Damme Els J. M. Van , Allen Anthony K. , Peumans Willy J.
Published: July 2007

Bulbs from three species of the plant family Amaryllidaceae (Narcissus pseudonurcissus L., Leucojum aestivum L. and Leucojum vernum L.) were found to contain mannose‐specific lectins. These lectins were serologically identical to a previously reported Amaryllidaceae lectin from Galanthus nivalis L. bulbs, but had a different molecular structure. The lectins described in this paper are dimeric proteins composed of subunits of 13 kDa, which are not held together by disulphide bridges. In hapten‐inhibition assays Amaryllidaceae lectins exhibited exclusive specificity towards mannose. Furthermore, they all had a high specific agglutination activity with trypsin‐treated rabbit erythrocytes, whereas human red blood cells were not agglutinated.