bluuebunny/crossref_metadata_2025 huggingface dataset:
Median Frequency Revisited
Authors: Jordan Denis , Stockmanns Gudrun , Kochs Eberhard F. , Schneider Gerhard
Published: August 2007

Background

In the past, several electroencephalographic parameters have been presented and discussed with regard to their reliability in discerning consciousness from unconsciousness. Some of them, such as the median frequency and spectral edge frequency, are based on classic spectral analysis, and it has been demonstrated that they are of limited capacity in differing consciousness and unconsciousness.

Methods

A generalized approach based on the Fourier transform is presented to improve the performance of electroencephalographic parameters with respect to the separation of consciousness from unconsciousness. Electroencephalographic data from two similar clinical studies (for parameter development and evaluation) in adult patients undergoing general anesthesia with sevoflurane or propofol are used. The study period was from induction of anesthesia until patients followed command after surgery and includes a reduction of the hypnotic agent after tracheal intubation until patients followed command. Prediction probability was calculated to assess the ability of the parameters to separate consciousness from unconsciousness.

Results

On the basis of the training set of 40 patients, a new spectral parameter called weighted spectral median frequency was designed, achieving a prediction probability of 0.82 on the basis of the "classic" electroencephalographic frequency range up to 30 Hz. Next, in the evaluation data set, the prediction probability was 0.79, which is higher than the prediction probability of median frequency (0.58) or spectral edge frequency (0.59) and the Bispectral Index (0.68) as calculated from the same data set.

Conclusions

A more general approach of the design of spectral parameters leads to a new electroencephalographic spectral parameter that separates consciousness from unconsciousness significantly better than the Bispectral Index.
Apolipoprotein E e4 Allele Increases the Risk of Early Postoperative Delirium in Older Patients Undergoing Noncardiac Surgery
Authors: Leung Jacqueline M. , Sands Laura P. , Wang Yun , Poon Annie , Kwok Pui-yan , Kane John P. , Pullinger Clive R.
Published: August 2007

Background

Whether patients who subsequently develop early postoperative delirium have a genetic predisposition that renders them at risk for postoperative delirium has not been determined.

Methods

The authors conducted a nested cohort study to include patients aged > or = 65 yr who were scheduled to undergo major noncardiac surgery requiring anesthesia. A structured interview was conducted preoperatively and for the first 2 days postoperatively to determine the presence of delirium, defined using the Confusion Assessment Method. Blood was drawn for measurement of the apolipoprotein genotypes. Bivariate tests of association were conducted between delirium and apolipoprotein genotypes and other potentially important risk factors. Variables that had significant bivariate association with postoperative delirium were entered in a forward multivariable logistic regression model.

Results

Of the 190 patients studied, 15.3% developed delirium on both days 1 and 2 after surgery. Forty-six patients (24.2%) had at least one copy of the apolipoprotein e4 allele. The presence of one copy of the e4 allele was associated with an increased risk of early postoperative delirium (28.3% vs. 11.1%; P = 0.005). Even after adjusting for covariates, patients with one copy of the e4 allele were still more likely to have an increased risk of early postoperative delirium (odds ratio, 3.64; 95% confidence interval, 1.51-8.77) compared with those without the e4 allele.

Conclusions

Apolipoprotein e4 carrier status was associated with an increased risk for early postoperative delirium after controlling for known demographic and clinical risk factors. These results suggest that genetic predisposition plays a role and may interact with anesthetic/surgical factors contributing to the development of early postoperative delirium.
Mechanical Ventilation in Healthy Mice Induces Reversible Pulmonary and Systemic Cytokine Elevation with Preserved Alveolar Integrity
Authors: Vaneker Michiel , Halbertsma Feico J. , van Egmond Jan , Netea Mihai G. , Dijkman Henry B. , Snijdelaar Dirk G. , Joosten Leo A. , van der Hoeven Johannes G. , Scheffer Gert Jan
Published: August 2007

Background

Mechanical ventilation (MV) may activate the innate immune system, causing the release of cytokines. The resulting proinflammatory state is a risk factor for ventilator-induced lung injury. Cytokine increase results from direct cellular injury but may also result from cyclic stretch alone as demonstrated in vitro: mechanotransduction. To study mechanotransduction in vivo, the authors used an animal MV model with clinically relevant ventilator settings, avoiding alveolar damage.

Methods

Healthy C57BL6 mice (n = 82) were ventilated (tidal volume, 8 ml/kg; positive end-expiratory pressure, 4 cm H2O; fraction of inspired oxygen, 0.4) for 30, 60, 120, and 240 min. Assigned animals were allowed to recover for 2 days after MV. Both pulmonary tissue and plasma interleukin (IL)-1alpha, IL-1beta, tumor necrosis factor alpha, IL-6, IL-10, and keratinocyte-derived chemokine levels were measured. Histopathologic appearance of lung tissue was analyzed by light microscopy and electron microscopy.

Results

In lung tissue, all measured cytokines and keratinocyte-derived chemokine levels increased progressively with MV duration. Light microscopy showed increased leukocyte influx but no signs of alveolar leakage or albumin deposition. Electron microscopy revealed intact epithelial cell and basement membranes with sporadically minimal signs of partial endothelial detachment. In plasma, increased levels of IL-1alpha, tumor necrosis factor alpha, IL-6, and keratinocyte-derived chemokine were measured after MV. In the recovery animals, cytokine levels had normalized and no histologic alterations could be found.

Conclusions

Mechanical ventilation induces reversible cytokine increase and leukocyte influx with preserved tissue integrity. This model offers opportunities to study the pathophysiologic mechanisms behind ventilator-induced lung injury and the contribution of MV to the "multiple-hit" concept.
Altered Contractile Response due to Increased β3-Adrenoceptor Stimulation in Diabetic Cardiomyopathy
Authors: Amour Julien , Loyer Xavier , Le Guen Morgan , Mabrouk Nejma , David Jean-Stéphane , Camors Emmanuel , Carusio Nunzia , Vivien Benoît , Andriantsitohaina Ramaroson , Heymes Christophe , Riou Bruno
Published: August 2007

Background

In the diabetic heart, the positive inotropic response to beta-adrenoceptor stimulation is altered and beta1 and beta2 adrenoceptors are down-regulated, whereas beta3 adrenoceptor is up-regulated. In heart failure, beta3-adrenoceptor stimulation induces a negative inotropic effect that results from endothelial nitric oxide synthase (NOS3)-derived nitric oxide production. The objective of our study was to investigate the role of beta3-adrenoceptor in diabetic cardiomyopathy.

Methods

beta-Adrenergic responses were investigated in vivo (dobutamine echocardiography) and in vitro (left ventricular papillary muscle) in healthy and streptozotocin-induced diabetic rats. The effect of beta3-adrenoceptor inhibition on the inotropic response was studied in vitro. Immunoblots and NOS activities were performed in heart homogenates (electron paramagnetic resonance) and isolated cardiomyocytes. Data are mean percentage of baseline +/- SD.

Results

The impaired positive inotropic effect was confirmed in diabetes both in vivo (121 +/- 15% vs. 160 +/- 16%; P < 0.05) and in vitro (112 +/- 5% vs. 179 +/- 15%; P < 0.05). In healthy rat, the positive inotropic effect was not significantly modified in presence of beta3-adrenoceptor antagonist (174 +/- 20%), nonselective NOS inhibitor (N -nitro-l-arginine methylester [l-NAME]; 183 +/- 19%), or selective NOS1 inhibitor (vinyl-l-N-5-(1-imino-3-butenyl)-l-ornithine [l-VNIO]; 172 +/- 13%). In diabetes, in parallel with the increase in beta3-adrenoceptor protein expression, the positive inotropic effect was partially restored by beta3-adrenoceptor antagonist (137 +/- 8%; P < 0.05), l-NAME (133 +/- 11%; P < 0.05), or l-VNIO (130 +/- 13%; P < 0.05). Nitric oxide was exclusively produced by NOS1 within diabetic cardiomyocytes. NOS2 and NOS3 proteins were undetectable.

Conclusions

beta3-Adrenoceptor is involved in altered positive inotropic response to beta-adrenoceptor stimulation in diabetic cardiomyopathy. This effect is mediated by NOS1-derived nitric oxide in diabetic cardiomyocyte.
Range and severity of a plant disease increased by global warming
Authors: Evans Neal , Baierl Andreas , Semenov Mikhail A , Gladders Peter , Fitt Bruce D.L
Published: August 2007

Climate change affects plants in natural and agricultural ecosystems throughout the world but little work has been done on the effects of climate change on plant disease epidemics. To illustrate such effects, a weather-based disease forecasting model was combined with a climate change model predicting UK temperature and rainfall under high- and low-carbon emissions for the 2020s and 2050s. Multi-site data collected over a 15-year period were used to develop and validate a weather-based model forecasting severity of phoma stem canker epidemics on oilseed rape across the UK. This was combined with climate change scenarios to predict that epidemics will not only increase in severity but also spread northwards by the 2020s. These results provide a stimulus to develop models to predict the effects of climate change on other plant diseases, especially in delicately balanced agricultural or natural ecosystems. Such predictions can be used to guide policy and practice in adapting to effects of climate change on food security and wildlife.
The stress field in a pulled cork and some subtle points in the semi-inverse method of nonlinear elasticity
Authors: De Pascalis Riccardo , Destrade Michel , Saccomandi Giuseppe
Published: August 2007

In an attempt to describe cork-pulling, we model a cork as an incompressible rubber-like material and consider that it is subject to a helical shear deformation superimposed onto a shrink fit and a simple torsion. It turns out that this deformation field provides an insight into the possible appearance of secondary deformation fields for special classes of materials. We also find that these latent deformation fields are woken up by normal stress differences. We present some explicit examples based on the neo-Hookean, the generalized neo-Hookean and the Mooney–Rivlin forms of the strain-energy density. Using the simple exact solution found in the neo-Hookean case, we conjecture that it is advantageous to accompany the usual vertical axial force by a twisting moment, in order to extrude a cork from the neck of a bottle efficiently. Then we analyse departures from the neo-Hookean behaviour by exact and asymptotic analyses. In that process, we are able to give an elegant and analytic example of secondary (or latent) deformations in the framework of nonlinear elasticity.
Reformulation of the standard theory of Fowler–Nordheim tunnelling and cold field electron emission
Authors: Forbes Richard G , Deane Jonathan H.B
Published: August 2007

This paper presents a major reformulation of the standard theory of Fowler–Nordheim (FN) tunnelling and cold field electron emission (CFE). Mathematical analysis and physical interpretation become easier if the principal field emission elliptic functionvis expressed as a functionv(l′) of the mathematical variablel′≡y2, whereyis the Nordheim parameter. For the Schottky–Nordheim (SN) barrier used in standard CFE theory,l′ is equal to the ‘scaled barrier field’f,which is the ratio of the electric field that defines a tunnelling barrier to the critical field needed to reduce barrier height to zero. The tunnelling exponent correction factorν=v(f). This paper separates mathematical and physical descriptions of standard CFE theory, reformulates derivations to be in terms ofl′ andf, rather thany, and gives a fuller account of SN barrier mathematics.v(l′) is found to satisfy the ordinary differential equationl′(1−l′)d2v/dl′2=(3/16)v; an exact series solution, defined by recurrence formulae, is reported. Numerical approximation formulae, with absolute error |ϵ|<8×10−10, are given forvand dv/dl′. The previously reported formulav≈1−l′+(1/6)l′ ln l′ is a good low-order approximation, with |ϵ|<0.0025. Withl′=f, this has been used to create good approximate formulae for the other special CFE elliptic functions, and to investigate a more universal, ‘scaled’, form of FN plot. This yields additional insights and a clearer answer to the question: ‘what does linearity of an experimental FN plot mean?’ FN plot curvature is predicted by a new functionw. The new formulation is designed so that it can easily be generalized; thus, our treatment of the SN barrier is a paradigm for other barrier shapes. We urge widespread consideration of this approach.
Pathwise convergent higher order numerical schemes for random ordinary differential equations
Authors: Kloeden Peter E , Jentzen Arnulf
Published: August 2007

Random ordinary differential equations (RODEs) are ordinary differential equations (ODEs) with a stochastic process in their vector field. They can be analysed pathwise using deterministic calculus, but since the driving stochastic process is usually only Hölder continuous in time, the vector field is not differentiable in the time variable, so traditional numerical schemes for ODEs do not achieve their usual order of convergence when applied to RODEs. Nevertheless deterministic calculus can still be used to derive higher order numerical schemes for RODEs via integral versions of implicit Taylor-like expansions. The theory is developed systematically here and applied to illustrative examples involving Brownian motion and fractional Brownian motion as the driving processes.
Analysis of the adiabatic limit for solitons in classical field theory
Authors: Stuart David M.A
Published: August 2007

We discuss the approximation of classical field theories by reduced systems of differential equations on the space of equilibria (the adiabatic limit). Various examples in which the approximation provides a useful description of the low-energy dynamics of solitons are discussed, including the sine-Gordon equation, the Yang–Mills–Higgs equations and the Chern–Simons–Schrödinger system. Particular emphasis is given to theorems on the validity of such approximations and proofs are given in some model cases.
What are the consequences of being left-clawed in a predominantly right-clawed fiddler crab?
Authors: Backwell P.R.Y , Matsumasa M , Double M , Roberts A , Murai M , Keogh J.S , Jennions M.D
Published: August 2007

Male fiddler crabs (genus
Uca
) have an enlarged major claw that is used during fights. In most species, 50% of males have a major claw on the left and 50% on the right. In
Uca vocans vomeris
, however, less than 1.4% of males are left-clawed. Fights between opponents with claws on the same or opposite side result in different physical alignment of claws, which affects fighting tactics. Left-clawed males mainly fight opposite-clawed opponents, so we predicted that they would be better fighters due to their relatively greater experience in fighting opposite-clawed opponents. We found, however, that (i) a left-clawed male retains a burrow for a significantly shorter period than a size-matched right-clawed male, (ii) when experimentally displaced from their burrow, there is no difference in the tactics used by left- and right-clawed males to obtain a new burrow; however, right-clawed males are significantly more likely to initiate fights with resident males, and (iii) right-clawed residents engage in significantly more fights than left-clawed residents. It appears that left-clawed males are actually less likely to fight, and when they do fight they are less likely to win, than right-clawed males. The low-level persistence of left-clawed males is therefore unlikely to involve a frequency-dependent advantage associated with fighting experience.
Character displacement among bat-pollinated flowers of the genusBurmeistera: analysis of mechanism, process and pattern
Authors: Muchhala Nathan , Potts Matthew D
Published: August 2007

Coexisting plants that share pollinators can compete through interspecific pollen transfer. A long-standing idea holds that divergence in floral morphology may reduce this competition by placing pollen on different regions of the pollinator's bodies. However, surprisingly little empirical support for this idea exists.Burmeisterais a diverse neotropical genus that exhibits wide interspecific variation in the degree to which the reproductive parts are exserted outside the corolla. CoexistingBurmeisterashare bats as their primary pollinators, and the degree of exsertion determines the site of pollen deposition on the bats' heads. Here we study the mechanism, process and pattern of floral character displacement for assemblages of coexistingBurmeistera. Flight cage experiments with bats and pairs ofBurmeisteraspecies demonstrate that the greater the divergence in exsertion length, the less pollen transferred interspecifically. Null model analyses of exsertion lengths for 19 species ofBurmeisteraacross 18 sites (each containing two to four species) demonstrate that observed assemblage structure is significantly overdispersed relative to what would be expected by chance. Local evolution, rather than ecological sorting, appears to be the primary process driving this pattern of overdispersion because local adaptation of the nine widespread species accounts for a large portion of the observed pattern. Taken together, results of this study provide strong support for the idea that competition through interspecific pollen transfer can drive character displacement in plants.
Habitat assessment ability of bumble-bees implies frequency-dependent selection on floral rewards and display size
Authors: Biernaskie Jay M , Gegear Robert J
Published: August 2007

Foraging pollinators could visit hundreds of flowers in succession on mass-flowering plants, yet they often visit only a small number—potentially saving the plant from much self-pollination among its own flowers (geitonogamy). This study tests the hypothesis that bumble-bee (
Bombus impatiens
) residence on a particular plant depends on an assessment of that plant's reward value relative to the overall quality experienced in the habitat. In a controlled environment, naive bees were given experience in a particular habitat (all plants having equal nectar quality or number of rewarding flowers), and we tested whether they learn about and adaptively exploit a new habitat type. Bees' residence on a plant (number of flowers probed per visit) was eventually invariant to a doubling of absolute nectar quality and increased only slightly with a doubling of absolute flower number in the habitat. These results help to explain why pollinators are quick to leave highly rewarding plants and suggest that the fitness of rewarding plant traits will often be frequency dependent. One implication is that geitonogamy may be a less significant constraint on the evolution of rewarding traits than generally supposed.
Evolution of parasite virulence when host responses cause disease
Authors: Day Troy , Graham Andrea L , Read Andrew F
Published: August 2007

The trade-off hypothesis of virulence evolution rests on the assumption that infection-induced mortality is a consequence of host exploitation by parasites. This hypothesis lies at the heart of many empirical and theoretical studies of virulence evolution, despite growing evidence that infection-induced mortality is very often a by-product of host immune responses. We extend the theoretical framework of the trade-off hypothesis to incorporate such immunopathology and explore how this detrimental aspect of host defence mechanisms affects the evolution of pathogen exploitation and hence infection-induced mortality. We argue that there are qualitatively different ways in which immunopathology can arise and suggest ways in which empirical studies can tease apart these effects. We show that immunopathology can cause infection-induced mortality to increase or decrease as a result of pathogen evolution, depending on how it covaries with pathogen exploitation strategies and with parasite killing by hosts. Immunopathology is thus an important determinant of whether public and animal health programmes will drive evolution in a clinically beneficial or detrimental direction. Immunopathology complicates our understanding of disease evolution, but can nevertheless be readily accounted for within the framework of the trade-off hypothesis.
Spatial adaptations for plant foraging: women excel and calories count
Authors: New Joshua , Krasnow Max M , Truxaw Danielle , Gaulin Steven J.C
Published: August 2007

We present evidence for an evolved sexually dimorphic adaptation that activates spatial memory and navigation skills in response to fruits, vegetables and other traditionally gatherable sessile food resources. In spite of extensive evidence for a male advantage on a wide variety of navigational tasks, we demonstrate that a simple but ecologically important shift in content can reverse this sex difference. This effect is predicted by and consistent with the theory that a sexual division in ancestral foraging labour selected for gathering-specific spatial mechanisms, some of which are sexually differentiated. The hypothesis that gathering-specific spatial adaptations exist in the human mind is further supported by our finding that spatial memory is preferentially engaged for resources with higher nutritional quality (e.g. caloric density). This result strongly suggests that the underlying mechanisms evolved in part as adaptations for efficient foraging. Together, these results demonstrate that human spatial cognition is content sensitive, domain specific and designed by natural selection to mesh with important regularities of the ancestral world.
The risk of establishment of aquatic invasive species: joining invasibility and propagule pressure
Authors: Leung Brian , Mandrak Nicholas E
Published: August 2007

Invasive species are increasingly becoming a policy priority. This has spurred researchers and managers to try to estimate the risk of invasion. Conceptually, invasions are dependent both on the receiving environment (invasibility) and on the ability to reach these new areas (propagule pressure). However, analyses of risk typically examine only one or the other. Here, we develop and apply a joint model of invasion risk that simultaneously incorporates invasibility and propagule pressure. We present arguments that the behaviour of these two elements of risk differs substantially—propagule pressure is a function of time, whereas invasibility is not—and therefore have different management implications. Further, we use the well-studied zebra mussel (
Dreissena polymorpha
) to contrast predictions made using the joint model to those made by separate invasibility and propagule pressure models. We show that predictions of invasion progress as well as of the long-term invasion pattern are strongly affected by using a joint model.
Estimating dinosaur maximum running speeds using evolutionary robotics
Authors: Sellers William Irvin , Manning Phillip Lars
Published: August 2007

Maximum running speed is an important locomotor parameter for many animals—predators as well as prey—and is thus of interest to palaeobiologists wishing to reconstruct the behavioural ecology of extinct species. A variety of approaches have been tried in the past including anatomical comparisons, bone scaling and strength, safety factors and ground reaction force analyses. However, these approaches are all indirect and an alternative approach is to create a musculoskeletal model of the animal and see how fast it can run. The major advantage of this approach is that all assumptions about the animal's morphology and physiology are directly addressed, whereas the exact same assumptions are hidden in the indirect approaches. In this paper, we present simple musculoskeletal models of three extant and five extinct bipedal species. The models predict top speed in the extant species with reasonably good agreement with accepted values, so we conclude that the values presented for the five extinct species are reasonable predictions given the modelling assumptions made. Improved musculoskeletal models and better estimates of soft tissue parameters will produce more accurate values. Limited sensitivity analysis is performed on key muscle parameters but there is considerable scope for extending this in the future.
Concurrent niche and neutral processes in the competition–colonization model of species coexistence
Authors: Cadotte Marc William
Published: August 2007

The importance of neutral dynamics is contentiously debated in the ecological literature. This debate focuses on neutral theory's assumption of fitness equivalency among individuals, which conflicts with stabilizing fitness that promotes coexistence through niche differentiation. I take advantage of competition–colonization trade-offs between species of aquatic micro-organisms (protozoans and rotifers) to show that equalizing and stabilizing mechanisms can operate simultaneously. Competition trials between species with similar colonization abilities were less likely to result in competitive exclusion than for species further apart. While the stabilizing mechanism (colonization differences) facilitates coexistence at large spatial scales, species with similar colonization abilities also exhibited local coexistence probably due to fitness similarities allowing weak stabilizing mechanisms to operate. These results suggest that neutral- and niche-based mechanisms of coexistence can simultaneously operate at differing temporal and spatial scales, and such a spatially explicit view of coexistence may be one way to reconcile niche and neutral dynamics.
The rise and fall of species: implications for macroevolutionary and macroecological studies
Authors: Liow Lee Hsiang , Stenseth Nils Chr
Published: August 2007

Knowing the geographic extents of species is crucial for understanding the causes of diversity distributions and modes of speciation and extinction. Species geographic ranges are often viewed as approximately constant in size in geological time, even though climate change studies have shown that historical and modern species geographic distributions are not static. Here, we use an extensive global microfossil database to explore the temporal trajectories of geographic extents over the entire lifespan of marine nannoplankton, diatom, planktic foraminifer and radiolarian species. We show that geographic extents are not static over geological time-scales. Temporal trajectories of species geographic ranges are asymmetric: the rise is quicker than the fall. We propose that once a species has overcome its initial difficulties in geographic establishment, it rises to its peak geographic extent. However, once this peak value is reached, it will also have a maximal number of species to interact with. The negative of these biotic interactions could then cause a gradual geographic decline. We discuss the multiple implications of our findings with reference to macroecological and macroevolutionary studies.
Which way to turn? Effect of direction of body asymmetry on turning and prey strike orientation in starry flounder Platichthys stellatus (Pallas) (Pleuronectidae)
Authors: Bergstrom C. A. , Palmer A. R.
Published: August 2007

Starry flounder Platichthys stellatus, a rare polymorphic flatfish exhibiting a large‐scale geographic cline in the frequency of right‐eyed (dextral) and left‐eyed (sinistral) morphs, was studied to investigate whether foraging behaviour (turning angle and prey strike orientation) differed between dextral and sinistral laboratory‐raised juveniles. Platichthys stellatus foraging on brine shrimp Artemia sp. nauplii tended to strike dorsally at prey (‘left’ to an observer for dextral flounder and ‘right’ to an observer for sinistral flounder), although this effect was stronger for sinistral fish. This dorsal tendency also increased with body size. Non‐strike behaviours (movements between strikes) were ventrally biased for both morphs. Maximum turn angles were larger for both morphs towards the dorsal side than the ventral side during prey strikes but were the same during non‐strike behaviours. The positioning of the eyes of the juvenile starry flounder was skewed towards the dorsal midline rather than being symmetrically placed between dorsal and ventral margins on the eyed side of each fish. The migrating eyes of dextral fish, however, were significantly closer to the dorsal midline than in sinistral fish. This, in addition to the more dorsally oriented prey strikes in sinistral fish, suggests that the morphs are not simple behavioural mirror images of one another and therefore may differ ecologically.
Morphological changes to the gills of killifish associated with severe parasite infection
Authors: Santiago Bass C , Khan S , Weis J. S
Published: August 2007

Highly significant changes were found in digenean metacercariae infected gills of killifishFundulus heteroclituswith respect to gill abnormalities. Gills infected with >1000 metacercariae exhibited up to 42 additional gill branches per fish when compared to less parasitized conspecifics. A strong positive correlation was found between abnormal gill morphology (number of branches) and the number of endoparasites present.
The hypoxic threshold for maximum cardiac performance in rainbow trout Oncorhynchus mykiss (Walbaum) during simulated exercise conditions at 18° C
Authors: Hanson L. M. , Farrell A. P.
Published: August 2007

Perfused rainbow trout Oncorhynchus mykiss hearts exposed to simulated exercise conditions (hypoxia, hyperkalemia and acidosis) at 18° C experienced complete failure of maximum cardiac performance at oxygen tensions <5·6 kPa and partial failure at <6·7 kPa. This hypoxic threshold, which occurred in the presence of maximal adrenergic stimulation (500 nM adrenaline), is unusually high compared with previous results at a colder acclimation temperature. Cardiac failure was primarily due to significant decreases (P < 0·05) in heart rate rather than cardiac stroke volume at all hypoxia levels tested.
Occurrence of pelagic stingrayPteroplatytrygon violacea(Bonaparte, 1832) in the North Sea
Authors: Ellis J. R
Published: August 2007

A mature male pelagic stingrayPteroplatytrygon violacea(99 cm total length, 33·5 cm disc length and 42 cm disc width; 2·5 kg) was caught by commercialNephropstrawl in the North Sea (atc. 54º49′ N; 0º57′ W) on 14 November 2005. Records ofP. violaceain the north‐east Atlantic are reviewed, with only two vagrant specimens known from the North Sea, representing the most northerly records of this species in the Atlantic Ocean.
The ontogeny of habitat associations in the tropical tiger tail seahorse Hippocampus comes Cantor, 1850
Authors: Morgan S. K. , Vincent A. C. J.
Published: August 2007

This study examined how habitat associations changed with ontogeny in the tiger tail seahorse Hippocampus comes Cantor, 1850, over four reef zones in a coral reef ecosystem. Hippocampus comes showed ontogenetic differences in their use of habitat at the scale of reef zones (macrohabitat) and holdfasts (microhabitat). Across reef zones, juvenile size classes (25–105 mm standard length, LS) were most abundant in wild macroalgal beds (Sargassum spp.) (55·7%), while adults (>105 mm LS) occupied both coral reefs (39·7%) and macroalgal beds (42·7%). Microhabitat use also varied with ontogeny. Juveniles generally used macroalgal holdfasts, while adults >135 mm LS used a greater diversity of specialized microhabitats that included branching sponges, branching corals and tall seagrass. Ontogenetic changes in habitat association, as well as size‐related shifts in crypsis and aggregation, suggest that H. comes experiences fitness trade‐offs that vary with size; juveniles may associate with habitat that reduces predation, while larger individuals may use distinct microhabitat in reef zones to optimize reproductive success. Results are discussed in the context of targeted exploitation, expanding artisanal mariculture, habitat damage from illegal fishing and reserve design.
Are distributions of fishes in tropical estuaries influenced by turbidity over small spatial scales?
Authors: Johnston R. , Sheaves M. , Molony B.
Published: August 2007

This study found no evidence that turbidity influenced the distribution of fishes in four tropical estuaries in north‐eastern Queensland. When both more turbid and less turbid environments were immediately available to Ambassis vachelli and Leiognathus equulus there was no difference in abundance between the more and less turbid environments and no correlated change in abundance as the difference in turbidity increased. A similar outcome was evident for an additional six species of fish. Furthermore, the distribution of fishes was not correlated with the distribution of an important prey species, juvenile banana prawns Penaeus merguiensis, which exhibited a clear response to differences in turbidity level with higher abundance in the more turbid samples, however, the magnitude of the difference did not alter with changes in the magnitude of the differences in turbidity.
Interannual differences in growth and hatch date distributions of age‐0 year walleye pollock Theragra chalcogramma (Pallas) sampled from the Shumagin Islands region of the Gulf of Alaska, 1985 – 2001
Authors: Dougherty A. B. , Bailey K. M. , Mier K. L.
Published: August 2007

Daily increments of age‐0 year walleye pollock Theragra chalcogramma otoliths from 1985 to 2001 were examined for interannual variability in growth and hatch dates. Fish were collected in summer and autumn surveys near the Shumagin Islands in the western Gulf of Alaska (GOA). Hatch date distributions of these fish were compared with hatch dates of larvae from spawning aggregations located in Shelikof Strait and the Shumagin Islands based on their spawning times. The hatch date distributions of age‐0 year fish captured from the Shumagin Islands area were similar to those observed for larvae from the Shelikof Strait spawning group. Age‐0 year fish whose hatch dates corresponded to the Shumagin Islands spawning, which occurred earlier in January and February, were not found. Sea surface temperature was associated with variability in hatch date distribution and growth.
Effects of light intensity and addition of carotene rich Dunaliella salina live cells on growth and antioxidant activity of Solea senegalensis Kaup (1858) larval and metamorphic stages
Authors: Cañavate J. P. , Prieto A. , Zerolo R. , Sole M. , Sarasquete C. , Fernández‐Díaz C.
Published: August 2007

Senegal sole Solea senegalensis larval and metamorphic stages were exposed to a range of light intensities (200, 1000 and 2000 lx) in cultures with or without supplementation of β‐carotene‐rich live Dunaliella salina cells. Antioxidant biomarkers such as superoxide dismutase (SOD), catalase (KAT), total glutathione peroxidase (t‐GPX) and malondialdehyde (MDA) were determined in larval and metamorphic stages. Growth was not affected (P > 0·05) either by light intensity or D. salina supplementation. Survival after metamorphosis was also unaffected by D. salina supplementation (mean ±s.e. 81·0 ± 2·5% against 80·6 ± 2·9% those fed the control algal diet) or light intensity (mean ±s.e. 74·3 ± 4·9% for 200 lx, 85·1 ± 2·7% for 1000 lx and 82·8 ± 5·2% for 2000 lx, respectively). Light intensity affected (P < 0·05) KAT and t‐GPX throughout development. SOD was only affected in metamorphosing larvae. The highest KAT and t‐GPX activities were detected when the lowest light intensity (200 lx) was used. Light had no effect (P > 0·05) on MDA at any stage. Supplementing the diet with D. salina did not affect SOD, KAT or t‐GPX and there was no interaction (P > 0·05) with light intensity. MDA was the only biomarker whose activity was significantly (P < 0·05) reduced when D. salina was supplemented to the larval rearing tanks. The effect of D. salina supplementation was only detected in metamorphosing larvae, whose MDA levels were noticeably higher than in earlier stages. These results are evidence of the antiperoxidative effect of β‐carotene from live algae in the larval rearing process of marine fishes.
Reproductive biology of a large, aggregation‐spawning serranid,Epinephelus fuscoguttatus(Forsskål): management implications
Authors: Pears R. J. , Choat J. H. , Mapstone B. D. , Begg G. A.
Published: August 2007

The reproductive biology of Great Barrier Reef populations of the long‐lived grouperEpinephelus fuscoguttatus(brown‐marbled grouper or flowery cod) was investigated using histological analyses. Evidence provided by gonad morphology and age‐based demographics suggested monandric protogynous hermaphroditism. Younger age groups contained only immature and mature females, and all males were above the size and age of 100% female maturity, consistent with secondary males derived from mature females by adult sex change. Fishing records confirmed that spawning aggregations of this species and the co‐occurringEpinephelus polyphekadion(camouflage grouper) are sometimes targeted on the Great Barrier Reef. Sampling data revealed strong spawning seasonality forE. fuscoguttatus, with a relatively narrow annual spawning period (November to January). The temporal pattern of reproductive activity within the spawning period, based on occurrence of near spawning ovaries (containing hydrated oocytes), indicated spawning events may occur throughout much of the lunar cycle and only partly coincide with seasonal fishing closure periods on the Great Barrier Reef. The results indicate that protection would be enhanced by a longer seasonal closure.
The effects of depth and salinity on juvenile Chinook salmon Oncorhynchus tshawytscha (Walbaum) habitat choice in an artificial estuary
Authors: Webster S. J. , Dill L. M. , Korstrom J. S.
Published: August 2007

The energetic cost for juvenile Chinook salmon Oncorhynchus tshawytscha to forage in habitats of different salinity and depth was quantified using a behavioural titration based on ideal free distribution theory. When given a choice between freshwater habitats of different depths (>0·83 or <0·83 m), a greater proportion of fish used the deeper habitat. When the deeper habitat was saltwater, the proportion of fish using it increased. When food was added to both the shallow freshwater and deep saline habitats, however, fish distribution returned to that observed when both habitats were fresh water. This indicates that the preference for deep saline habitats during the stratified phase was driven by some benefit associated with residency in deeper water, rather than salinity. The low perceived cost of low salinity might be in part due to the fish’s ability to minimize this cost by only making brief forays into the alternate freshwater habitat. When the food ration delivered to the more costly, shallow habitat was 50% greater than that delivered to the less costly, deep habitat, fish distributed themselves equally between the two habitats, presumably because of equal net benefits. This study demonstrates that juvenile Chinook salmon prefer deep saline habitat to shallow freshwater habitats but will make brief forays into the freshwater habitat if food availability is sufficiently high.
Autotriploid tench Tinca tinca (L.) larvae obtained by fertilization of eggs previously subjected to postovulatory ageing in vitro and in vivo
Authors: Flajšhans M. , Kohlmann K. , Ráb P.
Published: August 2007

Eggs of diploid tench Tinca tinca were half‐stripped out and stored for 0 (control batch), 1, 3 and 5 h at mean ±s.d. 17·0 ± 0·4 and 21·9 ± 0·5° C or for 0, 1, 2, 3, 4 and 5 h at 24·0 ± 0·0° C in vitro prior to fertilization. The eggs remaining in vivo in the fish kept at 17·0 ± 0·4 and 21·9 ± 0·5° C were collected and fertilized in the same time intervals. Fertilization rate and larval yield mostly decreased after 3–5 h storage of eggs both in vitro and in vivo and only the diploid larvae were found in all control batches. Triploid larval yields increased to a maximum 5·26% after 5 h in vitro storage at 24·0° C and 1·07 and 1·60% after 3 h in vitro storage at 21·9 and 17·0° C, respectively. Triploid larval yield during in vivo storage at 21·9° C reached a maximum 0·91% after 5 h. As the spontaneous autotriploid larvae arose solely from fertilized eggs previously subjected to postovulatory egg ageing by means of prolongated storage, the autotriploidy was probably caused by failure of extrusion of the second polar body.
Egg surface structure in the annual fishes Simpsonichthys (subgenera Ophthalmolebias and Xenurolebias) and Nematolebias (Teleostei: Cyprinodontiformes: Rivulidae): variability and phylogenetic significance
Authors: Fava D. , Toledo‐Piza M.
Published: August 2007

The surfaces of the egg chorion of nine species of Simpsonichthys, two of Nematolebias and eight other species of rivulids were studied with scanning electron microscopy revealing details of ornamentation that were previously undocumented. Surface structures of eggs of Simpsonichthys of the subgenus Ophthalmolebias are described for the first time: eggs of Simpsonichthys constanciae, Simpsonichthys perpendicularis, Simpsonichthys rosaceus and Simpsonichthys suzarti are ornamented with a very characteristic palm‐like structure, that is restricted to these species among the rivulids examined. The surface of the egg chorion of Simpsonichthys bokermanni lacks the well‐developed palm‐like structure, but has a characteristic conical projection, distinct from the structures of other rivulids examined, that is proposed as homologous to the palm‐like structure. Simpsonichthys bokermanni shares with Nematolebias papilliferus and Nematolebias whitei the presence of concentric rows of spiny projections around the micropylar region. Species of Simpsonichthys of the subgenus Ophthalmolebias, Simpsonichthys myersi (of the subgenus Xenurolebias), and N. whitei share the presence of large rounded protuberances on the surface of the egg chorion. The phylogenetic significance of these features are evaluated and discussed in light of current knowledge about rivulid relationships.
Diet and food preference of the waterbuck (Kobus ellipsiprymnus defassa) in the Pendjari National Park, Benin
Authors: Kassa Barthélémy , Libois Roland , Sinsin Brice
Published: August 2007

This study investigated composition and selectivity in diet for waterbuck in the Pendjari National Park in north‐western Benin, through the use of micrographic analysis of faecal samples. Three plant species (Panicum anabaptistum, Echinochloa stagnina and Andropogon gayanus) were regularly consumed all year round. Meanwhile, three other species (i.e., Hyparrhenia involucrata, Acroceras amplectens and Oryza barthii) are mostly found in its diet during the beginning of the rainy season. During the dry season, long life grasses (>40%) and tree forage (about 35%) were the most dominant life form in the diet. On the contrary at the beginning of the rainy season, annual species (> 50%) were dominant. In conclusion, the waterbuck has a grazer regime when plant species are abundant and a mixed diet during the dry season. Waterbuck’s food niche breath, defined by Hespenheide [Ecology and Evolution of communities. Harvard Univ. Press, 1975], was lower than 1, implying this antelope does not eat all food categories in a proportional way. Shannon diversity index showed that the diet was more diversified during the rainy season and less diversified at the end of the dry season. Based on [Ecology, 64 (1983), 1297] diet selectivity index, waterbuck exerted a positive selection on the major graminaceous species.
How much do junior staff know about common legal situations in paediatrics?
Authors: Ashtekar C. S. , Hande A. , Stallard E. , Tuthill D.
Published: August 2007

Background  Recent high‐profile medico‐legal cases such as the death of Victoria Climbie and the subsequent Laming report have highlighted widespread deficiencies in child protection practice. Junior doctors are the frontline staff regularly facing issues with potentially major legal implications, including child protection, Gillick competence, consent, and professional responsibility/accountability. It is therefore important for them to be aware and understand the Children Act, common medico‐legal principles and practices, particularly in the current, increasingly litigious climate.

Aims  (1) To determine junior medical staff's knowledge of legal issues involved in child protection and common basic legal situations, and (2) to assess whether experience and training improved this knowledge.

Methods  A standardized structured interview was developed exploring common issues with important legal implications for paediatric practice. It focused on: legal issues in child protection, the Children Act, awareness of the General Medical Council (GMC), principles of professional responsibility/accountability, the Bolam principle for good medical practice and Gillick competence. Basic demographic data were recorded. We attempted to contact all 180 paediatric junior medical staff in Wales by telephone.

Results  Interviews were conducted with 119/180 (66%) doctors: 46/56 specialist registrars (SpRs; 82%) and 73/124 senior house officers (SHOs; 59%). SpRs scored a median of 6.5 correct responses from a possible of 12 (range 3–11), compared with a median of 5 (range 1–11) by the SHOs (P < 0.0001; Mann–Whitney test). A third of SHOs and a fifth of SpRs were unaware that the GMC was the organization responsible for good medical practice in the UK. Similarly, a fifth of all juniors were ignorant of the legal age for consent. Approximately two‐thirds of the SHOs and half of the SpRs were ignorant that the police and social services have the legal power to protect the child in child protection cases. Alarmingly, none of the SHOs and only 11% of the SpRs were aware of the Bolam principle. SpRs scored significantly higher on topics of Gillick competence, legal right to see medical notes, consent, Children Act, burden of proof in civil and criminal court, and on Bolam principle. They also had received training more frequently than SHOs, which, when combined with their greater experience, probably explains these statistically significant differences.

Conclusion  Few junior staff have adequate knowledge of the basic legal principles and practice as they relate to children. Widespread deficiencies concerning the understanding of the Children Act and child protection powers exist.
Mental health of young people: a global public‐health challenge
Authors: Reading Richard
Published: August 2007

.
 
Patel V.,
Flisher A. J.,
Hetrick S. &
McGorry P.
(
2007
)

,
369
,
1302
–
13
.
 
DOI: 10.1016/S0140‐6736(07)60368–7.