bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐heating‐dependent thermal‐noise model using a distributed‐gate structure for RF applications
Authors: Kapoor Nirupama , Haldar Subhasis , Gupta Mridula , Gupta R. S.
Published: November 2003

In this paper, we present the gate‐resistance dependence on thermal noise of a fully depleted SOI MOS operating in an inversion regime with the gate structure's distributed nature. The various parameters used in this analysis are derived from the characteristics obtained by incorporating various short‐channel effects, such as channel length modulation, velocity saturation, and lattice temperature‐dependent mobility. The spectral density of the drain‐current noise is obtained and although it is observed that the noise in the frequency region >1 GHz is dominated by channel thermal noise, but the noise due to gate resistance is very large, in the frequency region <1 GHz. Therefore, the gate‐resistance dependence on thermal noise plays a major role when the device is operating in the RF range and must be incorporated. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 87–92, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11293
Remarks on “time domain modeling of electromagnetic wave propagation in Tellegen media”
Authors: Lakhtakia Akhlesh
Published: November 2003

The work of Barba et al.1 is fatally flawed on two counts: (i) the existence of Tellegen mediums is unrecognizable in modern electromagnetic theory, and (ii) the time‐domain constitutive relations used in the commented upon work are noncausal. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 92–93, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11294
Selection for imidacloprid resistance in Nilaparvata lugens: cross‐resistance patterns and possible mechanisms
Authors: Zewen Liu , Zhaojun Han , Yinchang Wang , Lingchun Zhang , Hongwei Zhang , Chengjun Liu
Published: November 2003

A field population of brown planthoppers (Nilaparvata lugens Stål) was collected and selected for imidacloprid resistance in the laboratory. The resistance increased by 11.35 times in 25 generations and the resistance ratio reached 72.83 compared with a laboratory susceptible strain. The selected resistant strain showed obvious cross‐resistance to all the acetylcholine receptor targeting insecticides tested (monosultap 1.44‐fold, acetamiprid 1.61‐fold, imidacloprid homologues JS599 2.46‐fold and JS598 3.17‐fold), but not to others. Further study demonstrated that TPP and DEM had no synergism on imidacloprid. However, PBO displayed significant synergism in some different strains, and the synergism increased with resistance (S strain 1.20, field population 1.43 and R strain 2.93). PBO synergism to cross‐resistant insecticides was also found in the resistant strain (monosultap 1.25, acetamiprid 1.39, JS598 1.94 and JS599 2.02). We concluded that esterase and glutathione S‐transferase play little role in imidacloprid detoxification. The increase of the P450‐monooxygenases detoxification is an important mechanism for imidacloprid resistance and target resistance may also exist in this species. Copyright © 2003 Society of Chemical Industry
An index for selective toxicity of miticides to phytophagous mites and their predators based on orchard trials
Authors: Hardman John M , Franklin Jeffrey L , Moreau Debra L , Bostanian Noubar J
Published: November 2003

Data from nine trials conducted from 1990 to 1998 in apple orchards in Nova Scotia and Quebec, Canada, were used to estimate the predator‐prey selectivity of miticides and their potential compatibility with biological control of mites. The European red mite Panonychus ulmi (Koch) was the dominant and more harmful phytophagous species, followed by the apple rust mite, Aculus schlechtendali (Nalepa). Two predacious mites, the phytoseiid, Typhlodromus pyri Sheuten, and the stigmaeid, Zetzellia mali (Ewing), were often found in the orchards. We used one minus the ratio of mite‐days in treated plots to those in the control plots as an index of population suppression and toxicity of the miticides. Miticides were then categorized into classes similar to those employed by the International Organization for Biological Control to rate pesticide toxicity to natural enemies of insect and mite pests. Selectivity of miticides was mostly based on toxicity to P ulmi, the major pest, versus toxicity to T pyri, the major predator, with some consideration of the two lesser species, A schlechtendali and Z mali. In most cases, our findings were in accord with other studies. Abamectin and clofentezine had favourable selectivity (more toxic to the two phytophagous mites than to T pyri). The higher recommended rate of pyridaben (450 g ha−1) and two rates of spirodiclofen (180 and 240 g ha−1) were neutral (equally toxic to pests and predators). The lower rate of pyridaben (216 g ha−1), dicofol, formetanate hydrochloride and propargite were unfavourably selective (more toxic to T pyri). A higher than recommended rate of pyridaben (2160 g ha−1) applied before bloom was disruptive—P ulmi‐days after treatment were actually greater than with the untreated control. P ulmi resistance to dicofol and propargite were probable complicating factors in some of the orchard trials. For the Department of Agriculture and Agri‐Food, Government of Canada, © Minister of Public Works and Government Services Canada 2003. Published by John Wiley & Sons, Ltd.
Insecticidal activity of the enantiomers of fipronil
Authors: Teicher Harald B , Kofoed‐Hansen Britt , Jacobsen Niels
Published: November 2003

The two enantiomers of the insecticide fipronil were made by preparative HPLC. The insecticidal activities of the racemic mixture and the two enantiomers against selected agricultural or household pests (cotton stainer, Dysdercus cingulatus F; grain weevil, Sitophilus granarius L and house fly, Musca domestica L) were determined. There was no significant difference in acute or residual activity between the racemic mixture and the enantiomers of fipronil, indicating that there is no preferred chiral form of the compound in these key species of important insects. This observation clearly suggests that there is no major scope for marketing the insecticide in a one‐enantiomer form. Copyright © 2003 Society of Chemical Industry
An experimental evaluation of scalar replacement on scientific benchmarks
Authors: Carr Steve , Sweany Philip
Published: November 2003

This paper describes our experiments comparing multiple scalar replacement algorithms to evaluate their effectiveness on entire scientific application benchmarks within the context of a production‐level compiler. We investigate at what point aggressive scalar replacement becomes detrimental and which dependence tests are necessary to give scalar replacement enough information to be effective. As many commercial optimizing compilers may include some version of scalar replacement as an optimization, it is important to determine how aggressive these algorithms need to be.

Previously, no study has examined ‘how much’ scalar replacement is sufficient and effective within the context of an existing highly optimizing compiler. Our experiments show that, on whole programs, simple algorithms and simple dependence analysis capture nearly all opportunities for scalar replacement found in scientific application benchmarks. While additional aggressiveness may lead to some performance gain in some individual loops, it also leads to performance degradation too often to be worth the risk when considering entire applications. Algorithms restricted to value reuse over at most one loop iteration and to fully redundant array references give the best results.

Our experiment further shows that scalar replacement is not only an effective optimization, but also a feasible one for commercial optimizers since the simple algorithms are not computationally expensive. Based upon our findings, we conclude that scalar replacement ought to be a part of any highly optimizing compiler because of its low cost and significant potential gain. Copyright © 2003 John Wiley & Sons, Ltd.
Time‐variable gravity signal of an anomalous redistribution of water mass in the extratropic Pacific during 1998–2002
Authors: Chao B. F. , Au A. Y. , Boy J.‐P. , Cox C. M.
Published: November 2003

Cox and Chao [2002] reported the detection of a large anomaly in the time series of Earth's dynamic oblateness J2, the lowest‐degree gravity spatial harmonic, in the form of a positive jump since 1998 overshadowing the decreasing secular trend in J2 caused primarily by the postglacial rebound (PGR). Here we report that recent data show that J2 has been rapidly returning toward “normal” (with PGR considered) since early 2001. In search of the geophysical and climatic causes for this “1998–2002 J2 anomaly,” we report an oceanographic event that took place in the extratropic north and south Pacific basins that was found to match remarkably well with the time evolution of the anomaly. We examine the leading (nonseasonal, extratropic Pacific) Empirical Orthogonal Function/Principal Component modes in the sea‐surface height (SSH) data from TOPEX/Poseidon, sea surface temperature (SST) data from the National Center for Environmental Predictions, and output fields of the Estimating the Circulation and the Climate of the Ocean (ECCO) ocean general circulation model (OGCM), including ocean bottom pressure (OBP) and temperature and salinity profiles. The phenomenon appears to be part of the Pacific Decadal Oscillation, and temporal correlations are made. However, quantitatively, the OBP field of the ECCO model predicts a J2 anomaly that is smaller in magnitude than the observed by a factor of about 3. We discuss various possibilities for reconciling this discrepancy in terms of inadequacies of present OGCMs and considering other geophysical contributions; a complete resolution of the J2 enigma awaits further studies.
SAFARI cruise: Mapping river discharge effects on Southern Brazilian shelf
Authors: Zavialov P. O. , Kostianoy A. G. , Möller O. O.
Published: November 2003

We report results of a hydrographic cruise organized within the framework of the Russian‐Brazilian joint project SAFARI (Southwestern Atlantic Freshwater Assimilation and River Inputs) and aimed at mapping special features of salinity and temperature distributions connected with the freshwater discharges from the Plata river and Patos‐Mirim lagoon estuaries on the Southern Brazilian shelf. Apart from the low salinity tongue in the inner shelf that has not been mapped in detail before, the intense river runoff results in strong temperature inversions (up to 4°C per 20–30 m) seen in the upper layer in winter. We argue that these inversions cannot result from the advective mechanism alone and should also be attributed to the freshwater related increase of vertical stability that leads to reduced mixing and thus enhanced winter cooling of the sea surface. Spatial distributions of salinity, inversion layer thickness and inversion magnitude over the shelf and continental slope are presented. In a belt extending for hundreds kilometers northward from the Plata estuary in the inner part of the shelf, salinity is up to 10 psu lower than that in the adjacent ocean beyond the river plumes. The spatial extent of the Patos‐Mirim lagoon plume is determined and the fine structure of the salinity distribution near the lagoon mouth is described.
Finite element modeling of nonlinear dispersive field line resonances: Trapped shear Alfvén waves inside field‐aligned density structures
Authors: Lu J. Y. , Rankin R. , Marchand R. , Tikhonchuk V. T. , Wanliss J.
Published: November 2003

Using a new two‐dimensional nonlinear finite element model, we investigate the interaction of dispersive shear Alfvén wave (SAW) field line resonances (FLRs) and ion acoustic waves in Earth's magnetosphere. We solve the full set of nonlinear reduced MHD equations self‐consistently in arbitrary geometries. Initially, a Cartesian box model is used to demonstrate the reliability of our numerical solution in determining the linear and nonlinear evolution of FLRs. Then the full reduced MHD equations with the effects of electron inertia, ion Larmor radius correction, and electron thermal pressure are solved in dipolar and stretched magnetic topologies. We show that time‐dependent dispersion and density steepening lead to localization of a highly structured FLR within an ionospheric (equatorial) density cavity (bump). When nonlinear effects are accounted for, we find that FLRs preferentially form in regions of low wave dispersion. Field line stretching and ponderomotive density redistribution lead to a significant reduction in FLR eigenfrequencies, bringing them into the range of observations. Nonlinear effects also cause a rapid acceleration of the timescale over which small perpendicular spatial scales appear. In our model, it is shown that density perturbations can be comparable to the equilibrium background density.
Simulation of spatial variability in snow and frozen soil
Authors: Cherkauer Keith A. , Lettenmaier Dennis P.
Published: November 2003

The spatial distribution of frozen soil and snow cover at the start of the spring melt season plays an important role in the generation of spring runoff and in the exchange of energy between the land surface and the atmosphere. Field observations were made at the University of Minnesota's Rosemount Agricultural Experiment Station to identify statistical distributions that can be used to describe the spatial variability of frozen soil and snow in macroscale hydrology models. These probability distributions are used to develop algorithms that simulate the subgrid spatial variability of snow and soil ice content for application within the framework of the variable infiltration capacity macroscale hydrologic model. Point simulations show that the new snow algorithm increases the melt rate for thin snowpacks, and the new soil frost algorithm allows more drainage through the soil during the winter. Simulations of the Minnesota River show that the new snow algorithm makes little difference to regional streamflow but does play an important role in the regional energy balance, especially during the spring snowmelt season. The new soil frost algorithm has a larger impact on spring streamflow and plays a minor role in the surface energy balance during the spring soil thaw season.
Validation of proton transfer reaction‐mass spectrometry (PTR‐MS) measurements of gas‐phase organic compounds in the atmosphere during the New England Air Quality Study (NEAQS) in 2002
Authors: de Gouw J. A. , Goldan P. D. , Warneke C. , Kuster W. C. , Roberts J. M. , Marchewka M. , Bertman S. B. , Pszenny A. A. P. , Keene W. C.
Published: November 2003

Organic compounds were measured by proton transfer reaction‐mass spectrometry (PTR‐MS) on board the National Oceanic and Atmospheric Administration's research ship Ronald H. Brown during the New England Air Quality Study (NEAQS) in July and August of 2002. PTR‐MS has the potential to measure many important organic species with a fast time response, but its validity has not been proven sufficiently. The results obtained by PTR‐MS during NEAQS were compared with those from (oxygenated) hydrocarbon measurements by gas chromatography/mass spectrometry (GC‐MS), peroxyacyl nitrate measurements by gas chromatography/electron capture detection, and carboxylic acid measurements by mist chamber/ion chromatography. The PTR‐MS and GC‐MS data for methanol, acetonitrile, acetone, isoprene, benzene, and toluene agreed within the measurement uncertainties. The comparison for C8 aromatics and acetaldehyde was less quantitative due to calibration inaccuracies. In addition, PTR‐MS measured the sum of methyl vinyl ketone and methacrolein at 71 amu, the sum of C9 aromatics at 121 amu, and the sum of monoterpenes at 81 and 137 amu. The PTR‐MS signal at 61 amu was found to correlate well with data for acetic acid. The signal at 73 amu correlated reasonably well with methyl ethyl ketone data, but the quantitative disagreement suggested interference from other species, possibly methyl glyoxal. The signal at 77 amu correlated well with data for peroxyacetyl nitrate, and the sensitivity inferred from the field data agreed within 30% with the results from laboratory calibrations. Finally, the signal at 105 amu was attributed to styrene and peroxy isobutyryl nitrate. These results prove that many important organic species can be measured accurately and with a fast response time by PTR‐MS.
Genetic Engineering and Autonomous Agency
Authors: Barclay Linda
Published: November 2003

abstract  In this paper I argue that the genetic manipulation of sexual orientation at the embryo stage could have a detrimental effect on the subsequent person's later capacity for autonomous agency. By focussing on an example of sexist oppression I show that the norms and expectations expressed with this type of genetic manipulation can threaten the development of autonomous agency and the kind of social environment that makes its exercise likely.
Archaeology and Respect for the Dead
Authors: Scarre Geoffrey
Published: November 2003

abstract  Contemporary archaeologists commonly acknowledge moral responsibilities to the descendants of the subjects whose remains they disturb. There has been comparatively little reflection within the professional community on whether they have duties to the dead themselves. I argue that doing wrong to the dead is not reducible to harming their successors; that there are ways in which archaeologists can wrong the dead qua the living persons they once were; and that nevertheless this may not have such radical implications for the practice of archaeology as might first be imagined.
George Bush and the 102d Congress: The Impact of Public and “Private” Veto Threats on Policy Outcomes
Authors: Conley Richard S.
Published: November 2003

Using archival data uncovered at the George Bush Presidential Library in College Station, Texas, this article develops a typology of veto threats and compares the effect of “private” and “public” veto threats on policy outcomes in the 102d Congress (1991‐1992) by legislative significance. The results suggest that formal models of veto threats have overstated the centrality of public rhetoric for an effective strategy. Private veto threats issued outside the public eye halted a host of minor legislation to which Bush objected. Veto threats that started off behind the scenes, only to be made public later, served as early signals that frequently won the president concessions on routine bills. By contrast, public threats on highly salient legislation were most likely to yield vetoes and inter‐branch confrontation.
Zeroing in on the Dark Side of the American Dream
Authors: Nickerson Carol , Schwarz Norbert , Diener Ed , Kahneman Daniel
Published: November 2003

Recent research has demonstrated that aspiring to the American Dream of financial success has negative consequences for various aspects of psychological well-being. The present longitudinal study examining the relation between the goal for financial success, attainment of that goal, and satisfaction with various life domains found that the negative impact of the goal for financial success on overall life satisfaction diminished as household income increased. The negative consequences of the goal for financial success seemed to be limited to those specific life domains that either concerned relationships with other people or involved income-producing activities, such as one's job; satisfactions with two of those life domains, however, were among the strongest predictors of overall life satisfaction in this sample of well-educated respondents in their late 30s. The negative consequences were particularly severe for the domain of family life; the stronger the goal for financial success, the lower the satisfaction with family life, regardless of household income.
Selective Attention Determines Emotional Responses to Novel Visual Stimuli
Authors: Raymond Jane E. , Fenske Mark J. , Tavassoli Nader T.
Published: November 2003

Distinct complex brain systems support selective attention and emotion, but connections between them suggest that human behavior should reflect reciprocal interactions of these systems. Although there is ample evidence that emotional stimuli modulate attentional processes, it is not known whether attention influences emotional behavior. Here we show that evaluation of the emotional tone (cheery/dreary) of complex but meaningless visual patterns can be modulated by the prior attentional state (attending vs. ignoring) used to process each pattern in a visual selection task. Previously ignored patterns were evaluated more negatively than either previously attended or novel patterns. Furthermore, this emotional devaluation of distracting stimuli was robust across different emotional contexts and response scales. Finding that negative affective responses are specifically generated for ignored stimuli points to a new functional role for attention and elaborates the link between attention and emotion. This finding also casts doubt on the conventional marketing wisdom that any exposure is good exposure.
Now You Feel It, Now You Don't
Authors: Jackson Daren C. , Mueller Corrina J. , Dolski Isa , Dalton Kim M. , Nitschke Jack B. , Urry Heather L. , Rosenkranz Melissa A. , Ryff Carol D. , Singer Burton H. , Davidson Richard J.
Published: November 2003

Recent theoretical accounts of emotion regulation assign an important role in this process to the prefrontal cortex, yet there is little relevant data available to support this hypothesis. The current study assessed the relation between individual differences in asymmetric prefrontal activation and an objective measure of uninstructed emotion regulation. Forty-seven participants 57 to 60 years old viewed emotionally arousing and neutral visual stimuli while eye-blink startle data were collected. Startle probes were also presented after picture presentation to capture the persistence or attenuation of affect following the offset of an emotional stimulus. Subjects with greater relative left-sided anterior activation in scalp-recorded brain electrical signals displayed attenuated startle magnitude after the offset of negative stimuli. This relation between resting frontal activation and recovery following an aversive event supports the idea of a frontally mediated mechanism involved in one form of automatic emotion regulation.
Holistic Processing of Faces in Preschool Children and Adults
Authors: Pellicano Elizabeth , Rhodes Gillian
Published: November 2003

Contrary to the encoding-switch hypothesis, recent research demonstrates that 6-year-olds do not rely solely on parts-based encoding to recognize upright faces. This research shows better recognition of face parts presented in the whole face than in isolation, indicating use of holistic encoding. The present study examined whether children younger than 6 years also recognize faces holistically. Four-year-olds, 5-year-olds, and adults were administered a part-whole face recognition task. Children below the age of 6 remembered parts from upright faces better when tested in the whole-face context than in isolation. This whole-face advantage did not occur when faces were inverted. Although children showed a smaller inversion decrement than adults and generally performed more poorly than adults, the different age groups showed similar patterns of performance, indicating that young preschoolers, like older children and adults, are able to recognize faces holistically.
Developments in Long-Term Explicit Memory Late in the First Year of Life
Authors: Bauer Patricia J. , Wiebe Sandra A. , Carver Leslie J. , Waters Jennie M. , Nelson Charles A.
Published: November 2003

Coincident with developments in the temporal-cortical explicit memory network, long-term recall abilities are newly emergent late in the first year of human life. We recorded event-related potentials (ERPs) in 9-month-olds as an index of the integrity of the neural substrate underlying a task thought to reflect explicit memory, namely, deferred imitation. ERP measures of recognition memory 1 week after unique laboratory experiences predicted whether and how much infants recalled of the experiences 1 month later. The findings further imply that memory storage and consolidation processes are a major source of variability in long-term recall memory late in the first year of life.
Relations Between Implicit Measures of Prejudice
Authors: Olson Michael A. , Fazio Russell H.
Published: November 2003

Some recent findings suggest that different implicit measures of prejudice assess the same underlying construct, but other work suggests that they may not. In this experiment, White participants completed a version of a priming measure of racial attitudes that either encouraged categorization of the face primes in terms of race or did not encourage such categorization, and then completed the Implicit Association Test. Correspondence between the two measures was found only when categorization by race was required on the priming measure. Moreover, participants appeared more prejudiced when they were led to construe individuals in terms of race than when they were not so encouraged. The discussion focuses on the potential for dissociations between evaluations of a category and evaluations of members of the category.
Conservative treatment of a radicular cyst in a 5‐year‐old child: a case report
Authors: Delbem A. C. B. , Cunha R. F. , Vieira A. E. M. , Pugliesi D. M. C.
Published: November 2003

The present report describes the management of a radicular cyst in a 5‐year‐old child. The treatment comprised extraction of the primary teeth involved followed by marsupialization. A removable appliance with a resin extension penetrating into the cystic cavity was used to help decompress the lesion. This treatment allowed rapid healing of the lesion and eruption of the permanent incisors without the need for orthodontic treatment.
Molar incisor hypomineralization: a questionnaire inventory of its occurrence in member countries of the European Academy of Paediatric Dentistry (EAPD)
Authors: Weerheijm K. L. , Mejàre I.
Published: November 2003

Objectives.  The objectives were to find out whether hypomineralized permanent first molars and incisors, known as Molar Incisor Hypomineralization (MIH), occurs all over Europe, whether its prevalence in each country is known and whether or not it is considered to be a clinical problem.

Sample and methods.  Clinical photos of MIH and a five‐item questionnaire were sent to members of the European Academy of Paediatric Dentistry (EAPD). A total of 59 questionnaires were sent to members in 31 countries. After one month a reminder was sent to non‐responders.

Results.  Fifty‐four dentists (92%) in 30 countries (97%) returned the questionnaire. MIH was stated to occur in all but one country (the Czech Republic). Nearly all the responders (97%) stated that they were familiar with the clinical appearance of MIH and a majority saw it as a clinical problem. Furthermore, a large majority of the responders (90%) considered it important to map the prevalence of MIH in European countries as such data are available to only a limited extent.

Conclusion.  Paediatric dentists in Europe are aware of MIH and the majority consider it to be a clinical problem. Only limited data are available on the prevalence of MIH. Comparable and representative prevalence studies are therefore urgently needed to gain more knowledge about the magnitude of MIH and related clinical problems.
Two‐body and three‐body wear of glass ionomer cements
Authors: Kunzelmann K.‐H. , Bürkle V. , Bauer C.
Published: November 2003

Objectives.  Glass ionomer cements (GIC) have been modified in an attempt to improve their mechanical properties. The objective of the present paper was to compare the two‐body and three‐body wear of four modified GIC. The tested materials were Fuji IX (GC Corporation), Hi‐Fi (Shofu) and Ketac Molar Aplicap (3M/ESPE). The cermet cement Ketac Silver Maxicap (3M/ESPE) was used as reference material.

Methods.  Two‐body wear tests were carried out in the computer controlled ‘artificial mouth’ of the Munich Dental School, three‐body wear was tested with the ACTA wear machine.

Results.  The resulting average two‐body wear rates (in µm) were: Fuji IX 327 (SD ± 82) < Ketac Molar 379 (SD ± 94) < Hi‐Fi 376 (SD ± 90) < Ketac silver 449 (SD ± 127). The differences between the materials were significant (P < 0·05, anova, modified LSD‐test) with the exception of Ketac Molar and Hi‐Fi. The average three‐body wear rates (in µm) were: Hi‐Fi 30 (SD ± 10) < Ketac Molar ± 42 (SD ± 12) < Fuji IX 49 (SD ± 14) < Ketac silver 73 (SD ± 23). The difference between Ketac silver and the three other materials was significant (P < 0·05, anova, modified LSD‐test). No significant difference was calculated between Hi‐Fi, Ketac Molar and Fuji IX.

Conclusions.  As Ketac Molar, Hi‐Fi and Fuji IX show better wear resistance compared to Ketac silver both in occlusal‐contact and contact‐free areas, it may be assumed that the wear resistance of a glass ionomer cement may be improved more by changing the powder : liquid ratio than by incorporating silver particles into the glass powder.
Sex differences in diving at multiple temporal scales in a size‐dimorphic capital breeder
Authors: Beck Carrie A. , Bowen W. Don , McMillan Jim I. , Iverson Sara J.
Published: November 2003

Air‐breathing marine predators can modify their diving behaviour to accommodate different patterns of prey abundance and distribution and may do so at multiple temporal scales (individual dives, bouts of dives and foraging trips).

The grey seal, Halichoerus grypus, is a size‐dimorphic, capital breeding species in which sex differences in foraging ecology have previously been found at the scale of individual dives. In this study, diving behaviour of male and female adult grey seals was examined at the temporal scales of dive bouts (41 males/46 females) and foraging trips (7 males/9 females) during the 8‐month prebreeding foraging period between 1992 and 1999 to investigate whether sex differences were evident at longer temporal scales.

Foraging trip duration did not differ between males and females. However, females (the smaller sex) spent significantly more time diving and less time hauled‐out on land between trips than males. This suggests that females are more selective than males when searching for prey. These differences are consistent with the effects of body‐size dimorphism on diving behaviour.

Virtually all dives occurred in bouts. At this scale, males and females showed significantly different seasonal patterns of most bout characteristics, including bout duration, percentage of bout spent at depth and effort (hours spent in bouts day−1).

Grey seals used four different types of bouts, differing in duration, depth, percentage bout spent at depth and the shape of individual dives within the bout. Males and females differed in the proportion of each bout type used and in the seasonal and day–night distribution of bout types.

Few bout characteristics varied significantly among years, despite interannual variation in prey abundance. Where interannual differences did occur, both sexes behaved in a similar way.

Different seasonal patterns in bouts of diving by males and females could not be accounted for by body‐size dimorphism or niche divergence, but were consistent with the hypothesis that females must recover condition earlier in the year than males to support the energetic costs of reproduction.
Recovery rates of benthic communities following physical disturbance
Authors: Dernie K. M. , Kaiser M. J. , Warwick R. M.
Published: November 2003

Despite numerous studies that have investigated the effects of physical disturbance on marine benthic communities, deducing the ecological significance of such events has been hampered by the specificity of individual studies. Less stable habitats (coarse, clean sands) are thought to recover more quickly than stable (muddy sands and mud) habitats but so far an empirical test of this paradigm has been lacking.

We describe a large‐scale field experiment that investigated the response of marine benthic communities within a variety of sediment types (clean sand, silty sand, muddy sand and mud) to physical disturbance. Sites were sampled for macrofauna and habitat characteristics (sediment organic content and water content, depth of water within disturbed pits) following disturbance, in order to examine any relationship between the rate of physical and biological recovery.

There were no detectable changes to the measured physical parameters following the disturbance with the exception of the water depth within disturbed areas. It was not possible to derive a linear relationship between the measured habitat characteristics (percentage silt and clay content) and the recovery trajectory of the associated community. However, the rate of sediment infilling of disturbed plots was strongly correlated to the recovery rate of the numbers of individuals within disturbed areas.

Clean sand communities had the most rapid recovery rate following disturbance, whereas communities from muddy sand habitats had the slowest physical and biological recovery rates. These findings concur with the predictions of a meta analysis of fishing disturbances for similar habitats.

We suggest that physical and biological recovery rates are mediated by a combination of physical, chemical and biological factors that differ in their relative importance in different habitats. Monitoring the infilling rate of physically disturbed patches of sediment has the potential to become a useful tool to predict the recovery rate of associated communities.
Territorial behaviour and population dynamics in red grouse Lagopus lagopus scoticus. II. Population models
Authors: Matthiopoulos Jason , Moss Robert , Mougeot François , Lambin Xavier , Redpath Steve M.
Published: November 2003

Recent experiments on cyclic red grouse populations discovered that aggressiveness, induced by testosterone implants, depressed population density for more than a year after the implants were exhausted.

This confirms the observation, also made in previous studies of this territorial species, that aggressiveness can determine population density. Additionally, it hints at a form of social memory that sustains the effect of episodes of high aggressiveness after their cause has ceased to exist.

We explore the logical consequences of this observation with a simple model of the interaction between population density and aggressiveness. A flexible function describes how aggressiveness changes from year to year as a function of population density. At low densities animals are tolerant to conspecifics and aggressiveness falls from one year to the next. Conversely, at high densities aggressiveness rises.

In the model, current aggressiveness is set by aggressiveness in the previous year, and modified by last year's population density (first version) or by current population density (second version).

We assume no particular behavioural mechanism underlying this process but derive conditions under which changes in aggressiveness, effected by density, can generate unstable dynamics.

The two versions of the model give fluctuations that differ in period and amplitude but have similar conditions for unstable dynamics. Specifically, the more abrupt the transition from tolerant to intolerant behaviour with increasing density, the more likely are cycles to occur.

We show how a previous model of the kinship hypothesis for red grouse cycles can be recast in the current terminology, and how the new models offer a more general way of examining red grouse population dynamics.
Antibody responses to filarial infective larvae are not dominated by the IgG4 isotype
Authors: Kurniawan‐Atmadja Agnes , Sartono Erliyani , Partono Felix , Yazdanbakhsh Maria , Maizels Rick M.
Published: November 2003

The humoral immune response in humans to filarial parasites is generally dominated by the IgG4 isotype, when measured by ELISA against somatic adult worm extract. In contrast, as we report here, antibodies reactive to somatic extracts of infective larvae are more equally represented by IgG1 and IgG4. Moreover, binding to surface exposed epitopes in immunofluorescence on larval stages is mediated foremost by IgG1 and IgM, secondarily by IgG2 and IgG3, and very little by IgG4. Both anti‐L3 surface and somatic antibodies are strongest in elephantiasis patients, and tend to increase with age. Antibody to the L3 surface is also present in most microfilaraemic individuals who bear no detectable antibodies to the surface of the microfilarial stage. These results demonstrate that a stage‐ and isotype‐specific response is mounted to the L3 surface which should be considered as a possible mediator of concomitant immunity in filariasis.
High rates of extracellular superoxide production by lichens in the suborder Peltigerineae correlate with indices of high metabolic activity
Authors: BECKETT R. P. , MINIBAYEVA F. V. , VYLEGZHANINA N. N. , TOLPYSHEVA T.
Published: November 2003

Rates of extracellular superoxide radical (O2· −) formation were measured in 34 species of lichens from different taxonomic groupings and contrasting habitats before and after desiccation stress. All 21 species from the suborder Peltigerineae produce O2· − extracellularly at high rates, even when they are not stressed. In addition, some species show a burst of O2· − production during rehydration following desiccation. Extracellular production of O2· − is almost absent in the species from other lichen groups. In general, production of high levels of O2· − and the existence of an inducible oxidative burst are best developed in species growing in wet microhabitats. Rates of O2· − production are also positively correlated to previously published indices of lichen metabolic activity. Preliminary studies on the identity of the O2· − producing enzymes suggest that they do not possess the classical characteristics of those suggested to produce reactive oxygen species in higher plants. Patterns of O2· − production are discussed in terms of the strategies used by different lichens groups in their defence against pathogenic fungi and bacteria.
Nitric oxide production in tobacco leaf cells: a generalized stress response?
Authors: GOULD K. S. , LAMOTTE O. , KLINGUER A. , PUGIN A. , WENDEHENNE D.
Published: November 2003

The function of nitric oxide (NO), a gaseous free radical emitted by many plants, is incompletely understood. In the present study the hypothesis that NO generation, like that of the reactive oxygen species, occurs as a general response to different environmental cues was tested. Leaf peels and mesophyll cell suspensions of Nicotiana tabacum cv. Xanthi were loaded with the NO‐specific fluorophore, diaminofluorescein, and subjected to an abiotic stressor. Light stress and mechanical injury had no apparent effect on NO production. In contrast, high temperatures, hyperosmotic stress, salinity and epi‐illumination in a microscope all led to rapid surges in NO‐induced fluorescence. The fluorescence originated from cells of the palisade mesophyll and across all epidermal cell types, including guard cells, subsidiary cells, and long and short trichomes. Fluorescence was evident first in the plastids, then in the nucleus and finally throughout the cytosol. Nicotiana plumbaginifolia cell suspensions expressing the calcium reporter aequorin provided evidence that, under hyperosmotic stress, NO participates in the elevation of free Ca2+ in the cytoplasm. The physiological significance of NO production in response to abiotic stressors is discussed.
Comparative analysis of photosensitivity in photosystem I donor and acceptor side mutants of Chlamydomonas reinhardtii
Authors: SOMMER F. , HIPPLER M. , BIEHLER K. , FISCHER N. , ROCHAIX J.‐D.
Published: November 2003

Electron input from plastocyanin into photosystem I (PSI) is slowed down in the Chlamydomonas reinhardtii mutants affected at the donor side (PsaF or PsaB, lumenal loop j) of PSI. In contrast, electron exit from PSI to ferredoxin is diminished in the PSI acceptor side PsaC mutants K35E and FB1. Although, the electron transfer reactions are diminished to a similar extent in both type of mutants, the PsaC mutants K35E and FB1 are more light‐sensitive than the PsaF‐deficient strain 3bF or the PsaB mutants E613N and W627F. To assess the differential photosensitivity of donor and acceptor side mutants fluorescence transients, gross oxygen evolution and uptake, PSII photo‐inhibition and rate of recovery were measured as well as NADP+ photoreduction. The NADP+ photoreduction measurements indicated that the donor side is limiting the reduction rate. In contrast, measurements of gross oxygen evolution and uptake showed that the reducing side limits linear electron transfer. However, under high light, donor and acceptor side mutations lead to PSII photo‐inhibition and to a diminished rate of PSII recovery, cause lipid peroxidation and result in a decrease in the levels of PSI and PSII. The wild type is not affected under the same conditions. These responses are most pronounced in the PsaC‐K35E and PsaB‐W627F mutants, and they correlate with the light sensitivity of these strains. The correlation between limitation of electron transfer through PSI and the formation of reactive oxygen species as a cause for the light‐sensitivity is discussed.
Spatial patterning of pigmentation in evergreen leaves in response to freezing stress
Authors: NICOTRA A. B. , HOFMANN M. , SIEBKE K. , BALL M. C.
Published: November 2003

Evergreen leaves of temperate climate plants are often subject to frosts. Changes in carbon gain patterns arise from freezing‐related tissue damage, and from interactions between light and temperature stress. We examined relationships between spatial patterns in freezing and concentrations of chlorophyll. Spatial patterns in pigmentation in leaves that had or had not been exposed to naturally occurring frosts were determined by conventional extraction techniques combined with high‐resolution hyperspectral imaging of reflectance from intact leaves. Predictive indices were developed to relate reflectance to chlorophyll content and chlorophyll a/b ratios within intact leaves. Leaves exposed to frosts had lower chlorophyll contents and more variable a/b ratios than protected leaves. In frost‐affected leaves, chlorophyll content was highest near leaf centres and decreased toward leaf tips and margins. Decline in chlorophyll content was associated with shifts in chlorophyll a/b ratios and increases in red pigmentation due to anthocyanin, with effects being greater on leaf sides exposed directly to the sun. These altered pigmentation patterns were consistent with patterns in freezing. The present results illustrate the fine scale of spatial variation in leaf response to freezing, and raise important questions about impacts of freezing on photosynthetic function in over‐wintering evergreens.
Relationship between boron and calcium in the N2‐fixing legume–rhizobia symbiosis
Authors: REDONDO‐NIETO M. , WILMOT A. R. , EL‐HAMDAOUI A. , BONILLA I. , BOLAÑOS L.
Published: November 2003

Because boron (B) and calcium (Ca2+) seem to have a strong effect on legume nodulation and nitrogen fixation, rhizobial symbiosis with leguminous plants, grown under varying concentrations of both nutrients, was investigated. The study of early pre‐infection events included the capacity of root exudates to induce nod genes, and the degree of adsorption of bacteria to the root surface. Both phenomena were inhibited by B deficiency, and increased by addition of Ca2+, resulting in an increase of the number of nodules. The infection and invasion steps were investigated by fluorescence microscopy in pea nodules harbouring a Rhizobium leguminosarum strain that constitutively expresses green fluorescent protein. High Ca2+ enhanced cell and tissue invasion by Rhizobium, which was highly inhibited after B deficiency. This was combined with an increased B concentration in nodules of plants grown on B‐free medium and supplemented with high Ca2+ concentrations, and that can be attributed to an increased B import to the nodules. Histological examination of indeterminate (pea) and determinate (bean) nodules showed an altered nodule anatomy at low B content of the tissue. The moderate increase in nodular B due to additional Ca2+ was not sufficient to prevent the abnormal cell wall structure and the aberrant distribution of pectin polysaccharides in B‐deficient treatments. Overall results indicate that the development of the symbiosis depends of the concentration of B and Ca2+, and that both nutrients are essential for nodule structure and function.
Characterization of Arabidopsis genes involved in biosynthesis of polyamines in abiotic stress responses and developmental stages
Authors: URANO K. , YOSHIBA Y. , NANJO T. , IGARASHI Y. , SEKI M. , SEKIGUCHI F. , YAMAGUCHI‐SHINOZAKI K. , SHINOZAKI K.
Published: November 2003

To characterize the genes for enzymes involved in the biosynthesis of polyamines (PAs), their expression profiles were investigated and the levels of PAs in Arabidopsis thaliana quantified. In the Arabidopsis genome, eight genes involved in PAs biosynthesis were identified and the expression profiles of these genes were analysed, not only under abiotic stress to determine whether they were stress‐inducible, constitutive, or stress‐repressible, but also in various organs to show their tissue specificity. AtADC2 and AtSPMS mRNAs, encoding arginine decarboxylase and spermine synthase, clearly increased in response to NaCl and dehydration and abscisic acid treatments. Stress‐inducible accumulation of AtADC2 mRNA correlated with putrescine (Put) accumulation under NaCl and dehydration treatments. In a cold condition, AtSAMDC2 mRNA increased significantly. AtADC2 and AtSAMDC2 mRNA were expressed in sexual organs such as flowers, buds and immature siliques. PAs also accumulated in sexual organs. These results suggest that the transcripts of eight genes involved in PA biosynthesis show different profiles of expression not only in response to environmental stress but also during plant development.
Sequence‐specific, Golgi‐dependent vacuolar targeting of castor bean 2S albumin
Authors: Brown Joanna C. , Jolliffe Nicholas A. , Frigerio Lorenzo , Roberts Lynne M.
Published: November 2003

The targeting of the castor bean (Ricinus communis) 2S albumin precursor has been investigated by expressing cDNA in transformed tobacco (Nicotiana tabacum) leaf cells and by following biosynthesis in the native tissue. Correct targeting in both tissues was accompanied by processing of the precursor. Delivery to vacuoles was sensitive to brefeldin A (BFA) treatment in both tissues and to perturbation of COPII function in tobacco, supporting the view that transport through the Golgi is required. The targeting signal for this Golgi‐dependent routing lies within the propeptide of the first heterodimer of proalbumin. This propeptide directed a normally secreted reporter protein to the vacuoles of tobacco cells in a Golgi‐dependent manner in vivo, unless a critical Leu residue was mutated, supporting the view that a sequence‐specific signal was needed to target a seed storage protein to the vacuoles of a vegetative cell.