bluuebunny/crossref_metadata_2025 huggingface dataset:
Protective Effects of Isoflurane Pretreatment in Endotoxin-induced Lung Injury
Authors: Reutershan Jörg , Chang Daniel , Hayes John K. , Ley Klaus
Published: February 2006

Background

The concept of antiinflammatory effects of volatile anesthetics is well established in vitro and in some organ systems. Their protective role in lung injury, however, remains to be elucidated. The authors hypothesized that in the lung, isoflurane pretreatment may attenuate neutrophil infiltration and reduce endotoxin-induced injury.

Methods

Male C57Bl/6 mice were exposed to aerosolized lipopolysaccharide. Neutrophil recruitment into the pulmonary vasculature and migration into the different lung compartments (interstitium and alveolar air space) were determined by flow cytometry. Capillary protein leakage, formation of lung edema, and concentration of the chemokines keratinocyte-derived chemokine (CXCL1) and macrophage inflammatory protein 2 (CXCL2/3) in bronchoalveolar lavage were compared in mice with or without isoflurane treatment (1.4% inspired for 30 min) at different times before and after endotoxin exposure.

Results

Endotoxin inhalation induced significant neutrophil migration into all lung compartments. Isoflurane pretreatment attenuated both neutrophil recruitment into lung interstitium and alveolar space when given 1 or 12 h before or 1 h after lipopolysaccharide but not at 4, 6, or 24 h before endotoxin exposure. Isoflurane pretreatment 1 or 12 h before lipopolysaccharide also reduced protein leakage and pulmonary edema. Production of CXCL1 and CXCL2/3 in the bronchoalveolar lavage was reduced when isoflurane was given 1 h but not 12 h before lipopolysaccharide, suggesting different mechanisms for early and late protection.

Conclusion

Isoflurane pretreatment reduces acute lung injury when given 1 or 12 h before an endotoxin challenge or within the first hour of an already established inflammation.
Differential Effect of Ketamine and Lidocaine on Spontaneous and Mechanical Evoked Pain in Patients with Nerve Injury Pain
Authors: Gottrup Hanne , Bach Flemming W. , Juhl Gitte , Jensen Troels S.
Published: February 2006

Background

The mechanisms underlying neuropathic pain are incompletely understood. Targeting specific molecular mechanisms in the pain signaling system may assist in understanding key features in neuropathic pains such as allodynia. This study examined the effect of systemically administered ketamine, an N-methyl-D-aspartate receptor antagonist and lidocaine, a sodium channel blocker, on spontaneous pain, brush-evoked pain, and pinprick-evoked pain in patients with nerve injury pain.

Methods

Twenty patients participated in two randomized, double-blinded, placebo-controlled, crossover experiments in which they, on four different days, received a 30-minute intravenous infusion of ketamine (0.24 mg/kg), lidocaine (5 mg/kg), or saline. Ongoing pain, pain evoked by brush and repetitive pinprick stimuli, and acetone was measured before, during, and after infusion.

Results

Ketamine significantly reduced ongoing pain and evoked pain to brush and pinprick, whereas lidocaine only reduced evoked pain to repetitive pinprick stimuli. In individual patients, there was no correlation between the pain-relieving effect of lidocaine and ketamine on ongoing or mechanically evoked pains.

Conclusions

N-methyl-D-aspartate receptor-linked systems and sodium channels are involved in generation and maintenance of pain in patients with peripheral nerve injury. It is likely that ongoing pain as well as mechanical hyperalgesia in individual patients is dependent on several separate molecular mechanisms.
Heart Rate Variability Predicts Severe Hypotension after Spinal Anesthesia
Authors: Hanss Robert , Bein Berthold , Weseloh Hendrik , Bauer Martin , Cavus Erol , Steinfath Markus , Scholz Jens , Tonner Peter H.
Published: February 2006

Background

Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension.

Methods

One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. Seventy patients were studied prospectively, assigned to one of two groups by their low to high frequency ratio (LF/HF) before SA. Sensitivity and specificity of LF/HF for prediction of decrease of SBP greater 20% of baseline were tested.

Results

Retrospective analysis showed differences of LF/HF depending on the degree of hypotension after SA. Prospective analysis demonstrated significant differences of SBP after SA depending on baseline LF/HF (mean +/- SD): low LF/HF (1.3 +/- 0.7) = > SBP: 91 +/- 8% of baseline versus high LF/HF (5.5 +/- 2.4) = > SBP: 66 +/- 10% of baseline (P < 0.05). Baseline LF/HF as well as high frequency and proportional decrease of SBP after SA correlated significantly, in contrast to baseline hemodynamic parameters heart rate and SBP. A receiver operator curve characteristic analysis showed a sensitivity and specificity of LF/HF > 2.5 of 85% to predict SBP decrease of greater than 20% of baseline after SA.

Conclusions

Heart rate variability analysis before SA may predict hypotension after SA with high sensitivity and specificity. LF/HF may be a tool to detect patients at high risk of hypotension due to SA. This indicates that the predictive value of LF/HF is superior to established predictors.
Atomistic characterization of three-dimensional lattice trapping barriers to brittle fracture
Authors: Zhu Ting , Li Ju , Yip Sidney
Published: February 2006

We present a detailed account of an atomistic study of three-dimensional lattice trapping barriers to brittle fracture in Si. By means of a prototypical interatomic potential model, we map out the molecular details of the evolution of atomically sharp cracks in the (111) cleavage plane with straight crack fronts along the

and

directions, respectively. The thermally activated processes of bond rupturing along the crack front are quantitatively characterized using a reaction pathway sampling scheme. The calculated minimum energy paths reveal a mechanism of kink-pair formation and migration in facilitating the crack front advancement. We show that the physical origin of directional anisotropy in cleavage crack propagation can be attributed to a difference in the kink-pair formation energy for different crack orientations. The effects of interatomic potentials are delineated by comparing the Stillinger–Weber model with an environment-dependent model.
A self-consistent polycrystal model for the spontaneous polarization of ferroelectric ceramics
Authors: Su Y , Weng G.J
Published: February 2006

Motivated by the observation that the spontaneous polarization process of a ferroelectric polycrystal under the influence of a superimposed stress and/or electric field involves heterogeneous evolution of the ferroelectric phase among its constituent grains, a self-consistent electromechanical model is developed to determine the effective behaviour of the polycrystalline ceramic from such a heterogeneous electromechanical state. We start out from consideration of a micromechanics-based thermodynamic process to establish the kinetic equation of the crystallite and use it to evaluate the evolution of its ferroelectric domain. Then together with the Curie–Weiss law for the dielectric constants of the tetragonal phase, a dual-phase mixture theory is adopted to determine the change of its electromechanical moduli as temperature cools down below its Curie point. The overall property of the polycrystal is subsequently calculated by the self-consistent model through orientational average over its constituent grains. This two-level micromechanics model is applied to examine the shift of Curie temperature and evolution of the effective electromechanical moduli of a BaTiO
3
ceramic under cooling. The calculated results show that its Curie temperature decreases with increasing hydrostatic pressure, but increases with a superimposed axial compression or a biased electric field. The predicted temperature shift and change of the dielectric constants are found to be consistent with experimental observations.
Creep and recrystallization of large polycrystalline masses. II. Constitutive theory for crystalline media with transversely isotropic grains
Authors: Faria Sérgio H , Kremer Gilberto M , Hutter Kolumban
Published: February 2006

By combining the theory of mixtures with continuous diversity with Liu's method of Lagrange multipliers, a thermodynamically consistent constitutive theory is derived for large polycrystalline masses made up of transversely isotropic crystallites. The media under study are supposed to be incompressible and subjected to strain-induced anisotropy and recrystallization effects. Owing to the fabric (texture) changes caused by lattice rotation and polygonization, the polycrystal and its composing grains are modelled as polar media. Among other results of the theory, the existence of a
dislocation potential
is inferred, which represents for polycrystals the counterpart to the chemical potential of physical chemistry. Furthermore, exploitation of the dissipation inequality gives rise to the notion of a
driving pressure for grain boundary migration
. Besides, the vanishing of the Voigt couple stress is analysed together with the existence of
internal stresses and couples
responsible for the bending/twisting of crystallites by polygonization and heterogeneous strain.
Size dependence and stochastic nature of yield strength of micron-sized crystals: a case study on Ni3Al
Authors: Ngan A.H.W , Zuo L , Wo P.C
Published: February 2006

Recent experiments indicate that the first yield point of micron-sized metals exhibits significant statistical scatter as well as strong dependence on the specimen size. In this work, molecular dynamics (MD) simulations are carried out to investigate the onset of shear deformation in a small block of material, using an embedded atom potential for the intermetallic Ni3Al alloy. Incipient plasticity in the form of homogeneous dislocation generation is observed to occur at atomic sites with interatomic displacements approaching one-half of the Shockley partial Burgers vector. From the distribution function of the interatomic displacements observed in the MD simulations, the probability of a general material volume surviving under given loading conditions is predicted. The survival probability is then calculated for several situations, including homogeneous deformation and nanoindentation, to predict the critical load for incipient plasticity to occur in these situations. The predicted results are compared to micro-pillar compression and nanoindentation experiments on Ni3Al available in the literature.
On the complete integrability and linearization of nonlinear ordinary differential equations. II. Third-order equations
Authors: Chandrasekar V.K , Senthilvelan M , Lakshmanan M
Published: February 2006

We introduce a method for finding general solutions of third-order nonlinear differential equations by extending the modified Prelle–Singer method. We describe a procedure to deduce all the integrals of motion associated with the given equation, so that the general solution follows straightforwardly from these integrals. The method is illustrated with several examples. Further, we propose a powerful method of identifying linearizing transformations. The proposed method not only unifies all the known linearizing transformations systematically but also introduces a new and generalized linearizing transformation. In addition to the above, we provide an algorithm to invert the non-local linearizing transformation. Through this procedure the general solution for the original nonlinear equation can be obtained from the solution of the linear ordinary differential equation.
VectorJ-integral analysis of crack initiation at the edge of complete sliding contact
Authors: Ma Lifeng , Korsunsky Alexander M
Published: February 2006

In this paper, the crack initiation at contact surface of solids is investigated on the basis of the concept of potential energy release rate. The expressions for path-independent integral vectorJi(i=1, 2) are derived and applied to the consideration of the process of crack initiation. The relationship is then established between the value of the path-independent integral vectorJiand the potential energy release rate for crack initiation in an arbitrary orientation. This allows the prediction of crack initiation angle on the basis of the maximum energy release rate criterion. The surface crack initiation angle in fretting fatigue is determined analytically as a function of the friction coefficient of the edge contact. This theoretical result is compared with the existing experimental results reported in the literature and a good agreement is found. The formulation provides a novel basis for numerical modelling of the complex process of fretting fatigue.
The effect of temporal dependence on the estimation of the frequency of extreme ocean climate events
Authors: Luceño Alberto , Menéndez Melisa , Méndez Fernando J
Published: February 2006

The term ‘extreme ocean climate estimation’ refers to the assessment of the statistical distribution of extreme oceanographical geophysical variables. Components of the ocean climate are variables, such as the storm surge, wind velocity and significant wave height. Important characteristics of extreme ocean climate are the frequencies of the exceedances of ocean climate variables over selected thresholds. Assuming that exceedances are statistically independent of each other, their frequencies can be estimated using non-homogeneous Poisson processes. However, exceedances often exhibit temporal dependency because of the tendency of storms to gather in clusters. We assess the effect of these dependencies on the estimation of the rate of occurrence of extreme events. Using a database built under the HIPOCAS European project, which covers the Western Mediterranean Sea, we compare the performance of the non-homogeneous Poisson process approach versus a new model that allows for temporal dependency. We show that the latter outperforms the former in terms of the resulting goodness of fit and significance of the parameters involved.
Wavelet based spectral finite element modelling and detection of de-lamination in composite beams
Authors: Mitra M , Gopalakrishnan S
Published: February 2006

In this paper, a model for composite beam with embedded de-lamination is developed using the wavelet based spectral finite element (WSFE) method particularly for damage detection using wave propagation analysis. The simulated responses are used as surrogate experimental results for the inverse problem of detection of damage using wavelet filtering. The WSFE technique is very similar to the fast fourier transform (FFT) based spectral finite element (FSFE) except that it uses compactly supported Daubechies scaling function approximation in time. Unlike FSFE formulation with periodicity assumption, the wavelet-based method allows imposition of initial values and thus is free from wrap around problems. This helps in analysis of finite length undamped structures, where the FSFE method fails to simulate accurate response. First, numerical experiments are performed to study the effect of de-lamination on the wave propagation characteristics. The responses are simulated for different de-lamination configurations for both broad-band and narrow-band excitations. Next, simulated responses are used for damage detection using wavelet analysis.
Travelling fronts in porous media combustion: existence and a singular limit
Authors: Gordon Peter , Ryzhik Lenya
Published: February 2006

We consider a model for the propagation of a subsonic detonation wave through a porous medium introduced by Sivashinsky (Sivashinsky 2002Proc. Combust. Inst.29, 1737–1761). We show that it admits travelling wave solutions that converge in the limit of zero temperature diffusivity to the travelling fronts of a reduced system constructed in Gordonet al. (Gordonet al. 2002Asymptotic Anal.29, 309–321).
Do electromagnetic waves harbour gravitational waves?
Authors: Bramson Brian
Published: February 2006

In linearized, Einstein–Maxwell theory on flat spacetime, an oscillating electric dipole is the source of a spin-2 field. Within this approximation to general relativity, it is shown that electromagnetic waves harbour gravitational waves.
An
O
(
h

N

) interface model of a three-dimensional curved interphase in conduction phenomena
Authors: Benveniste Y
Published: February 2006

A thin isotropic three-dimensional curved interphase of thickness
h
between two isotropic media is considered in the setting of thermal conduction. This interphase is modelled by a surface between the two neighbouring media, and appropriate interface conditions on it are derived for the temperature and normal heat flux fields. The derivation makes use of Taylor expansions for the fields and is correct to
O
(
h

N

), where
h
denotes the thickness of the interphase. The jumps for the temperature and normal heat flux in the interface model are given in terms of a hierarchy of surface differential forms, which depend on the conductivities of the interphase and surrounding media, and involve surface derivatives of the temperature and normal heat flux along the interface. The analysis is directly transferable to the analogous physical phenomena of electrical conduction, dielectrics, magnetism, diffusion, flow in porous media and anti-plane elasticity.
Compressibility of two-dimensional pores having
n
-fold axes of symmetry
Authors: Ekneligoda Thushan C , Zimmerman Robert W
Published: February 2006

The complex variable method and conformal mapping are used to derive a closed-form expression for the compressibility of an isolated pore in an infinite two-dimensional, isotropic elastic body. The pore is assumed to have an
n
-fold axis of symmetry, and be represented by at most four terms in the mapping function that conformally maps the exterior of the pore into the interior of the unit circle. The results are validated against some special cases available in the literature, and against boundary-element calculations. By extrapolation of the results for pores obtained from three and four terms of the Schwarz–Christoffel mapping function for regular polygons, the compressibilities of a triangle, square, pentagon and hexagon are found (to at least three digits). Specific results for some other pore shapes, more general than the quasi-polygons obtained from the Schwarz–Christoffel mapping, are also presented. An approximate scaling law for the compressibility, in terms of the ratio of perimeter-squared to area, is also tested. This expression gives a reasonable approximation to the pore compressibility, but may overestimate it by as much as 20%.
A note on Love's equation with damping
Authors: Jordan P.M , Feuillade C
Published: February 2006

The dynamic propagation of a Heaviside input signal in a semi-infinite, dissipative/dispersive medium is considered. The exact solution to this problem, which corresponds to Stokes' first problem of fluid mechanics, is obtained and analysed using integral transform methods. Special/limiting cases are noted and numerical methods are used to illustrate the analytical findings. Specifically, the following results are presented: (i) critical values of the dispersion coefficient are noted and examined; (ii) for large values of time, the solution exhibits Taylor shock-like behaviour; (iii) the half-peak point of the Taylor shock exhibits a phase shift that depends on the dispersion coefficient. Lastly, links to other fields are noted and some associated mathematical relations are presented.
Remarks on modified improved Boussinesq equations in one space dimension
Authors: Cho Yonggeun , Ozawa Tohru
Published: February 2006

We study the existence and scattering of global small amplitude solutions to modified improved Boussinesq equations in one dimension with nonlinear term

behaving as a power

as

. Solutions are considered in

space for all

. According to the value of
s
, the power nonlinearity exponent
p
is determined. Liu (Liu 1996
Indiana Univ. Math. J
.
45
, 797–816) obtained the minimum value of
p
greater than 8 at

for sufficiently small Cauchy data. In this paper, we prove that
p
can be reduced to be greater than

at

and the corresponding solution
u
has the time decay, such as

as

. We also prove non-existence of non-trivial asymptotically free solutions for

under vanishing condition near zero frequency on asymptotic states.
Function of a key morphological innovation: fusion of the cichlid pharyngeal jaw
Authors: Darrin Hulsey C
Published: February 2006

The pharyngeal jaw of cichlids may represent a key innovation that facilitated their unparalleled trophic divergence. In cichlids, ‘fusion’ of the lower pharyngeal jaw (LPJ) results from suturing between the two lower ceratobranchials. To examine, what novel abilities a more extensively fused pharyngeal jaw may confer, the function of LPJ suturing was examined in Heroine cichlids. Greater LPJ suturing, pharyngeal jaw splitting under compression and the forces used to crush molluscs in the wild suggest increased LPJ fusion in the trophically polymorphic
Herichthys minckleyi
operates to strengthen the pharyngeal jaw. Among Heroine cichlid species, the presence of an external LPJ suture and feeding specialization on molluscs was evolutionarily quite variable, but greater LPJ fusion estimated from the amount of external suturing was highly correlated with molluscivory. Throughout cichlid diversification, increased pharyngeal jaw fusion via suturing has likely helped to reinforce the LPJ during pharyngeal processing thereby facilitating the ability of cichlids to exploit durable prey.
Variation among species in proteomic sulphur content is related to environmental conditions
Authors: Bragg Jason G , Thomas Dominique , Baudouin-Cornu Peggy
Published: February 2006

The elemental composition of proteins influences the quantities of different elements required by organisms. Here, we considered variation in the sulphur content of whole proteomes among 19 Archaea, 122 Eubacteria and 10 eukaryotes whose genomes have been fully sequenced. We found that different species vary greatly in the sulphur content of their proteins, and that average sulphur content of proteomes and genome base composition are related. Forces contributing to variation in proteomic sulphur content appear to operate quite uniformly across the proteins of different species. In particular, the sulphur content of orthologous proteins was frequently correlated with mean proteomic sulphur contents. Among prokaryotes, proteomic sulphur content tended to be greater in anaerobes, relative to non-anaerobes. Thermophiles tended to have lower proteomic sulphur content than non-thermophiles, consistent with the thermolability of cysteine and methionine residues. This work suggests that persistent environmental growth conditions can influence the evolution of elemental composition of whole proteomes in a manner that may have important implications for the amount of sulphur used by living organisms to build proteins. It extends previous studies that demonstrated links between transient changes in environmental conditions and the elemental composition of subsets of proteins expressed under these conditions.
Cross-continental differences in patterns of predation: will naive moose in Scandinavia ever learn?
Authors: Sand Håkan , Wikenros Camilla , Wabakken Petter , Liberg Olof
Published: February 2006

Predation has been recognized as a major selective force in the evolution of behavioural characteristics of mammals. As a consequence of local predator extinction, prey may lose knowledge about natural predators but usually express behavioural adjustments after return of predators. Human harvest may replace natural predation but prey selection may differ from that of natural predators leading to a change in the behavioural response of prey. We show that hunting success (HS) of re-colonizing wolves (
Canis lupus
) on moose (
Alces alces
) in Scandinavia was higher than reported in North America, where moose have been continuously exposed to wolves and grizzly bears. We found no evidence that moose expressed behavioural adjustments that lowered the HS of wolves in territories that had been occupied by wolves for up to 21 years. Moose behaviour towards wolves and humans typically differs in Scandinavia compared to North America. We explain the differences found to be caused by variation in predation pressure by large carnivores and the rate, and mode, of human harvest during the twentieth century.
Spatial network structure and amphibian persistence in stochastic environments
Authors: Fortuna Miguel A , Gómez-Rodríguez Carola , Bascompte Jordi
Published: February 2006

In the past few years, the framework of complex networks has provided new insight into the organization and function of biological systems. However, in spite of its potential, spatial ecology has not yet fully incorporated tools and concepts from network theory. In the present study, we identify a large spatial network of temporary ponds, which are used as breeding sites by several amphibian species. We investigate how the structural properties of the spatial network change as a function of the amphibian dispersal distance and the hydric conditions. Our measures of network topology suggest that the observed spatial structure of ponds is robust to drought (compared with similar random structures), allowing the movement of amphibians to and between flooded ponds, and hence, increasing the probability of reproduction even in dry seasons.
Age-structured effects and disease interference in childhood infections
Authors: Huang Yunxin , Rohani Pejman
Published: February 2006

Recent studies have demonstrated that ecological interference among some childhood diseases may have important dynamic consequences. An interesting question is, when would we expect the interference effect to be pronounced? To address the issue, here we develop a seasonally forced two-disease age-structured model, using empirically derived age-specific force of infection (ASFOI) for numerous infections of childhood. Our comparative numerical analysis shows that when the ASFOIs for the two diseases largely overlap, the dynamics predicted by the two-disease model are generally different from those predicted by the analogous single-disease model, suggesting strong fingerprints of disease interference. When the ASFOIs overlap less, on the other hand, both diseases behave as predicted by the single-disease model, suggesting weak interference. We conclude that age structure is an important factor that should be taken into account in order to explore the underlying mechanisms of disease interference.
Having it all: historical energy intakes do not generate the anticipated trade-offs in fecundity
Authors: Johnston S.L , Grune T , Bell L.M , Murray S.J , Souter D.M , Erwin S.S , Yearsley J.M , Gordon I.J , Illius A.W , Kyriazakis I , Speakman J.R
Published: February 2006

An axiom of life-history theory, and fundamental to our understanding of ageing, is that animals must trade-off their allocation of resources since energy and nutrients are limited. Therefore, animals cannot ‘have it all’—combine high rates of fecundity with extended lifespans. The idea of life-history trade-offs was recently challenged by the discovery that ageing may be governed by a small subset of molecular processes independent of fitness. We tested the ‘trade-off’ and ‘having it all’ theories by examining the fecundities of C57BL/6J mice placed onto four different dietary treatments that generated caloric intakes from −21 to +8.6% of controls. We predicted body fat would be deposited in relation to caloric intake. Excessive body fat is known to cause co-morbidities that shorten lifespan, while caloric restriction enhances somatic protection and increases longevity. The trade-off model predicts that increased fat would be tolerated because reproductive gain offsets shortened longevity, while animals on a restricted intake would sacrifice reproduction for lifespan extension. The responses of body fat to treatments followed our expectations, however, there was a negative relationship between reproductive performance (fecundity, litter mass) and historical intake/body fat. Our dietary restricted animals had lower protein oxidative damage and appeared able to combine life-history traits in a manner contrary to traditional expectations by having increased fecundity with the potential to have extended lifespans.
Direct versus indirect sexual selection: genetic basis of colour, size and recruitment in a wild bird
Authors: Hadfield Jarrod D , Burgess Malcolm D , Lord Alex , Phillimore Albert B , Clegg Sonya M , Owens Ian P.F
Published: February 2006

Indirect and direct models of sexual selection make different predictions regarding the quantitative genetic relationships between sexual ornaments and fitness. Indirect models predict that ornaments should have a high heritability and that strong positive genetic covariance should exist between fitness and the ornament. Direct models, on the other hand, make no such assumptions about the level of genetic variance in fitness and the ornament, and are therefore likely to be more important when environmental sources of variation are large. Here we test these predictions in a wild population of the blue tit (
Parus caeruleus
), a species in which plumage coloration has been shown to be under sexual selection. Using 3 years of cross-fostering data from over 250 breeding attempts, we partition the covariance between parental coloration and aspects of nestling fitness into a genetic and environmental component. Contrary to indirect models of sexual selection, but in agreement with direct models, we show that variation in coloration is only weakly heritable

, and that two components of offspring fitness—nestling size and fledgling recruitment—are strongly dependent on parental effects, rather than genetic effects. Furthermore, there was no evidence of significant positive genetic covariation between parental colour and offspring traits. Contrary to direct benefit models, however, we find little evidence that variation in colour reliably indicates the level of parental care provided by either males or females. Taken together, these results indicate that the assumptions of indirect models of sexual selection are not supported by the genetic basis of the traits reported on here.
The absence of sharks from abyssal regions of the world's oceans
Authors: Priede Imants G , Froese Rainer , Bailey David M , Bergstad Odd Aksel , Collins Martin A , Dyb Jan Erik , Henriques Camila , Jones Emma G , King Nicola
Published: February 2006

The oceanic abyss (depths greater than 3000 m), one of the largest environments on the planet, is characterized by absence of solar light, high pressures and remoteness from surface food supply necessitating special molecular, physiological, behavioural and ecological adaptations of organisms that live there. Sampling by trawl, baited hooks and cameras we show that the Chondrichthyes (sharks, rays and chimaeras) are absent from, or very rare in this region. Analysis of a global data set shows a trend of rapid disappearance of chondrichthyan species with depth when compared with bony fishes. Sharks, apparently well adapted to life at high pressures are conspicuous on slopes down to 2000 m including scavenging at food falls such as dead whales. We propose that they are excluded from the abyss by high-energy demand, including an oil-rich liver for buoyancy, which cannot be sustained in extreme oligotrophic conditions. Sharks are apparently confined toca30% of the total ocean and distribution of many species is fragmented around sea mounts, ocean ridges and ocean margins. All populations are therefore within reach of human fisheries, and there is no hidden reserve of chondrichthyan biomass or biodiversity in the deep sea. Sharks may be more vulnerable to over-exploitation than previously thought.
Biocomplexity in a highly migratory pelagic marine fish, Atlantic herring
Authors: Ruzzante Daniel E , Mariani Stefano , Bekkevold Dorte , André Carl , Mosegaard Henrik , Clausen Lotte A.W , Dahlgren Thomas G , Hutchinson William F , Hatfield Emma M.C , Torstensen Else , Brigham Jennifer , Simmonds E. John , Laikre Linda , Larsson Lena C , Stet René J.M , Ryman Nils , Carvalho Gary R
Published: February 2006

The existence of biologically differentiated populations has been credited with a major role in conferring sustainability and in buffering overall productivity of anadromous fish population complexes where evidence for spatial structure is uncontroversial. Here, we describe evidence of correlated genetic and life history (spawning season linked to spawning location) differentiation in an abundant and highly migratory pelagic fish, Atlantic herring,
Clupea harengus
, in the North Sea (NS) and adjacent areas. The existence of genetically and phenotypically diverse stocks in this region despite intense seasonal mixing strongly implicates natal homing in this species. Based on information from genetic markers and otolith morphology, we estimate the proportional contribution by NS, Skagerrak (SKG) and Kattegat and western Baltic (WBS) fish to mixed aggregations targeted by the NS fishery. We use these estimates to identify spatial and temporal differences in life history (migratory behaviour) and habitat use among genetically differentiated migratory populations that mix seasonally. Our study suggests the existence of more complex patterns of intraspecific diversity than was previously recognized. Sustainability may be compromised if such complex patterns are reduced through generalized management (e.g. area closures) that overlooks population differences in spatial use throughout the life cycle.
Basic concepts in plasma accelerators
Authors: Bingham Robert
Published: February 2006

In this article, we present the underlying physics and the present status of high gradient and high-energy plasma accelerators. With the development of compact short pulse high-brightness lasers and electron and positron beams, new areas of studies for laser/particle beam–matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high-acceleration gradients. These include the plasma beat wave accelerator (PBWA) mechanism which uses conventional long pulse (∼100 ps) modest intensity lasers (
I
∼10
14
–10
16
 W cm
−2
), the laser wakefield accelerator (LWFA) which uses the new breed of compact high-brightness lasers (<1 ps) and intensities >10
18
 W cm
−2
, self-modulated laser wakefield accelerator (SMLWFA) concept which combines elements of stimulated Raman forward scattering (SRFS) and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches the plasma wakefield accelerator.

In the ultra-high intensity regime, laser/particle beam–plasma interactions are highly nonlinear and relativistic, leading to new phenomenon such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm
−1
have been generated with monoenergetic particle beams accelerated to about 100 MeV in millimetre distances recorded. Plasma wakefields driven by both electron and positron beams at the Stanford linear accelerator centre (SLAC) facility have accelerated the tail of the beams.
Some important issues to do with long-term sea level change
Authors: Woodworth Philip L
Published: February 2006

This paper gives an overview of several important issues concerned with the measurement and understanding of long-term sea level change, which is one of the most important topics in sea level science. The issues discussed span science, technology and our ability to fund and operate the national and global observation networks required for a proper understanding of long-term change and its impacts. Many of these topics were explored at a ‘Celebration of UK sea level science’ at the Royal Society on 16–17 February 2004, and are discussed further in a number of papers in this volume.
Recent relative sea-level trends: an attempt to quantify the forcing factors
Authors: Plag Hans-Peter
Published: February 2006

Local sea-level is affected by a number of forcing factors, which all contribute to the trends observed by tide gauges. Here we use the fingerprints of main factors contributing to secular sea-level trends to construct an initial empirical model that explains best the trends in sea-level as recorded by the large number of coastal tide gauges over the last 50 years. The forcing factors considered include steric changes derived from observations, post-glacial rebound as predicted by geophysical models and mass changes in the Greenland and Antarctic ice sheets as predicted by the static sea-level equation. The approximation of the observed spatial pattern of sea-level trends through a model based on the spatial fingerprints of the main forcing factors fully utilizes the information contents of the available observations and models and allows the interpolation of the sea-level trends between the tide gauges. As a result, we obtain the global picture of sea-level trends due to the forcing factors accounted for in the analysis. Moreover, we derive constraints on the mass changes of the large ice sheets.

The empirical models explain about 15% of the variance of the sea-level trends. Nevertheless, the models are correlated with the observations on the level of 0.38±0.07, indicating that most of the unexplained variance is due to contributions with small spatial scales. Averaged over the last five decades, the results indicate that the Antarctic and Greenland ice sheets have been melting with an equivalent contribution to global sea-level rise of 0.39±0.11 and 0.10±0.05 mm yr
−1
, respectively. The steric signal derived from observations is clearly identified in the sea-level trends and is found to be at a minimum of 0.2 mm yr
−1
, with the most likely value being close to 0.35 mm yr
−1
. The global tide gauge network, which covers only a small fraction of the ocean surface, appears to sense an average sea-level rise larger than the global average. Extrapolating the regression models to the global ocean and taking into account the uncertainties in the extrapolation results in a most likely global average of the order of 1.05±0.75 mm yr
−1
.
Developing constraints on the relative sea-level curve for the northeast of Ireland from the mid-Holocene to the present day
Authors: Orford Julian D , Murdy Joanne , Freel Robert
Published: February 2006

Tide-gauge records from the north of Ireland have been digitized to generate annual estimates of both mean-sea-level (MSL) position from Malin Head (1958–1998), and mean tidal level (MTL) from Belfast Harbour (1918–2002). Both sites exhibit substantial annual variation, but show overall long-term shallow rates of falling relative sea-level change (RSLC) that are very similar at −0.2 mm a
−1
(±0.37 mm a
−1
) for Belfast and −0.16 mm a
−1
(±0.17 mm a
−1
) for Malin. Using these rates as constraints, plus other constraints of inferred RSLC rates from the mid-Holocene, an approximation of the likely profile of RSLC rates for the northeast of Ireland since 6 ka ago is presented.
Stratospheric ozone depletion
Authors: Rowland F. Sherwood
Published: February 2006

Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO
2
, NO, NO
2
, Cl and ClO. The NO
X
and ClO
X
chains involve the emission at Earth's surface of stable molecules in very low concentration (N
2
O, CCl
2
F
2
, CCl
3
F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules.
How much can treatment reduce national drug problems?
Authors: Reuter Peter , Pollack Harold
Published: February 2006

Aims  Treatment of drug addiction has been the subject of substantial research and, in contrast to several other methods of reducing drug use, has been found to be both effective and cost‐effective. This review considers what is known about how much a nation can reduce its drug problems through treatment alone and what is known at the aggregate level about the effectiveness of prevention and enforcement.

Methods  The literature on the effectiveness of treatment, prevention and enforcement are reviewed, and set in a policy analytical framework. 

Findings  Many studies have found treatment to have large effects on individuals’ consumption and harms. However, there is an absence of evidence that even relatively well‐funded treatment systems have much reduced the number of people in a nation who engage in problematic drug use. For prevention, the scientific literature shows useful and modest effects at the individual level but there is little support for substantial aggregate effects. For enforcement, research has failed almost uniformly to show that intensified policing or sanctions have reduced either drug prevalence or drug‐related harm. Nor—outside the UK—is there more than a modest effort to improve the evidence base for making decisions about the appropriate level of enforcement of drug prohibitions.

Conclusions  Treatment can justify itself in terms of reductions in harms to individuals and communities. However, even treatment systems that offer generous access to good quality services will leave a nation with substantial drug problem. Finding effective complementary programs remains a major challenge.
What drug policies cost. Estimating drug policy expenditures in Sweden, 2002: work in progress
Authors: Ramstedt Mats
Published: February 2006

Aim  To estimate drug policy expenditures in Sweden for 2002.

Data and method  The various governmental agencies with drug policy responsibilities were identified and then requested to provide information on their actual spending on these activities. For most agencies additional information was obtained from special studies or expert opinion.

Findings  Drug policy expenditures are not easily identified in Swedish official statistics. The results have a very wide range between 500 and 1400 million Euros during 2002, with 950 million Euros as a baseline estimate. Two items each account for almost 60% of the total—police (including customs and courts) and corrections—whereas treatment expenditures and income support represent about one‐fifth, respectively. Comparison with the most recent previous estimate (1991) shows a substantial higher level in 2002.

Conclusions  The findings suggest that a great deal of money is invested in drug policy measures in Sweden today and that it has most probably increased since the early 1990s. This development probably reflects the increase in number of problematic drug users in Sweden as well as increasing attention paid to the drug problem, foremost in the criminal justice system. More work is needed in developing a drug budget that is more easily available and in producing more reliable estimates both across sectors and across time. The need to develop the conceptualization of drug policy measures is also discussed.
The three year course of alcohol use disorders in the general population: DSM‐IV, ICD‐10 and the Craving Withdrawal Model
Authors: De Bruijn Carla , Van Den Brink Wim , De Graaf Ron , Vollebergh Wilma A. M.
Published: February 2006

Aims  To determine the course of alcohol use disorders (AUD) in a prospective general population study using three different classification systems: Diagnostic and Statistical Manual version IV (DSM‐IV), International Classification of Diseases version 10 (ICD‐10) and the craving withdrawal model (CWM). The latter is an alternative classification, which requires craving and withdrawal for alcohol dependence and raises the alcohol abuse threshold to two criteria.

Design, setting and participants  Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a large (n = 7076) representative general population study with a baseline and 1‐ and 3‐year follow‐up assessments.

Measurements  Diagnostic status according to DSM‐IV, ICD‐10 and CWM at baseline and at follow‐up was established using a structured interview (Composite International Diagnostic Interview: CIDI).

Findings  DSM‐IV abuse, ICD‐10 harmful use and CWM abuse all showed a favourable course with remission rates of 81, 89 and 71%, respectively, at 1‐year follow‐up and 85, 92 and 79% at 3‐year follow‐up. Dependence according to DSM‐IV, ICD‐10 and CWM had a somewhat less favourable course, with remission rates (no dependence) of 67, 67 and 57% at 1‐year follow‐up and 74, 69 and 73% at 3‐year follow‐up, respectively. Subjects who were remitted at 1‐year follow‐up showed relapse‐rates of 0–14% for dependence and 4–12% for abuse at 3‐year follow‐up. Although CWM diagnoses tended towards greater diagnostic stability than DSM‐IV and ICD‐10, most differences were not significant.

Conclusion  The conviction that addiction is a chronic relapsing disease may apply to treatment‐seeking alcoholics, but our data show a far more favourable course of alcohol use disorders in the general population.