bluuebunny/crossref_metadata_2025 huggingface dataset:
Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators
Authors: Rittershofer W. , Schroeder C. B. , Esarey E. , Grüner F. J. , Leemans W. P.
Published: June 2010

Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser-plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal and transverse fields differ and, hence, the required tapering differs. The length over which the tapered plasma density becomes singular is calculated. Linear plasma tapering as well as discontinuous plasma tapering, which moves beams to adjacent plasma wave buckets, is also considered. The energy gain of an accelerated electron in a tapered laser-plasma accelerator is calculated and the laser pulse length to optimize the energy gain is determined.
Morphotropic phase boundary and electrical properties in (1−x)Bi0.5Na0.5TiO3−xBi(Zn0.5Ti0.5)O3 lead-free piezoceramics
Authors: Zhang Shan-Tao , Yan Feng , Yang Bin
Published: June 2010

( 1 − x ) Bi 0.5 Na 0.5 TiO 3 − x Bi ( Zn 0.5 Ti 0.5 ) O 3 [(1−x)BNT−xBZT, x=0, 0.025, 0.0375, 0.050, and 0.075] lead-free piezoceramics were prepared and their structures and electrical properties were investigated. It is found that BZT can increase the Curie temperature of BNT. A morphotropic phase boundary (MPB) separating rhombohedral and tetragonal phases exists near x=0.0375. As the result, the MPB composition shows improved electrical properties; the saturated polarization, remnant polarization, and coercive field are 42.0 μC/cm2, 36.5 μC/cm2, and 3.5 kV/mm, respectively, while the piezoelectric coefficient, planar electromechanical coupling factor, and unipolar strain are 92 pC/N, 0.22, and 0.08%, respectively. The structures and electrical properties are discussed by comparing with that of other BNT-based piezoceramics. Our results do not only supplement for BNT-based lead-free piezoceramics, but also may provide a way to develop new lead-free piezoceramics with high Curie temperature.
Concentration fluctuations in a binary glass former investigated by x-ray photon correlation spectroscopy
Authors: Schramm Sebastian , Blochowicz Thomas , Gouirand Emmanuel , Wipf Robert , Stühn Bernd , Chushkin Yuriy
Published: June 2010

We investigate structure and dynamics of concentration fluctuations in the binary glass former methyl-tetrahydrofuran and oligomeric methyl metacrylate by photon correlation spectroscopy with partially coherent x-rays from a synchrotron source. Although the system is macroscopically well miscible and optically clear in the full temperature range, calorimetric and dielectric measurements reveal two distinct glass transition temperatures. The relaxation of long range concentration fluctuations turns out to be diffusive and exponential only well above the upper glass transition temperature. As the characteristic time τcf for concentration fluctuations shows a much weaker temperature dependence than the α-relaxation both traces finally intersect upon lowering the temperature. Thus, close to Tg, the concentration fluctuations show pronounced features of out-of-equilibrium dynamics such as compressed relaxation functions and a crossover to a ballistic wave vector dependence of τcf, like previously observed in various soft matter systems. Moreover, the analysis of time-resolved correlation functions reveals that the relaxation of concentration fluctuations around Tg involves pronounced dynamic heterogeneities.
Dust acoustic solitary waves in a charge varying relativistic dusty plasma
Authors: Tribeche Mouloud , Boukhalfa Soufiane , Zerguini Taha Houssine
Published: June 2010

The problem of nonlinear variable charge dust acoustic solitary waves in dusty plasma with relativistic electrons and ions is addressed. The appropriate relativistic charging currents, derived within the theoretical framework of the orbit-limited motion theory, are used. Our results show that in such a plasma, rarefactive spatially localized dust acoustic waves can exist. Their spatial patterns are significantly modified by the relativistic effects. In particular, it may be noted that relativistic effects make the solitary structure spikier. Our results should help to understand the salient features of coherent nonlinear structures that may occur in relativistic space plasmas.
Communications: Observation of two classes of isomers of hydrated electrons in sodium-water clusters
Authors: Forck Richard M. , Dauster Ingo , Schieweck Yasmin , Zeuch Thomas , Buck Udo , Ončák Milan , Slavíček Petr
Published: June 2010

A new class of sodium-water clusters with a low lying ionization potential (IP) is characterized by their photoionization spectra in molecular beam experiments. This implies that Na(H2O)n clusters coexist for n≥15 in two forms of significant abundances being distinguished by their IPs of ∼2.8 and ∼3.2 eV. A tentative quantum chemical characterization was achieved by simulating ionization spectra for selected cluster sizes using an ab initio molecular dynamics approach. Experiment and theory suggest that the Na+-e− distance is significantly larger in the clusters with the lower IP. This indicates that the solvated electron in Na(H2O)n clusters very probably forms with the Na+ counterion both a solvent separated and a contact ion pair.
About the complex relation between short-circuit photocurrent, imprint and polarization in ferroelectric thin films
Authors: Pintilie L. , Stancu V. , Vasile E. , Pintilie I.
Published: June 2010

The short-circuit photocurrent was measured in ferroelectric capacitors of polycrystalline and epitaxial quality. The interest was to study the possible relation between photocurrent and back-switching phenomena due to ferroelectric polarization imprint, as suggested by Pintilie et al. [J. Appl. Phys. 101, 064109 (2007)]. An interesting relation between the shape of the ferroelectric hysteresis loop and the shape of the photocurrent spectral distribution was found. In polycrystalline samples, the shape of spectral distribution and the sign of photocurrent are changing in time, although the hysteresis is almost symmetrical. However, the hysteresis is not rectangular as in the case of epitaxial films. This behavior suggests a subtle relation between polarization back-switching and photocurrent. In epitaxial samples a peculiar dependence between photocurrent and polarization imprint was found. All these are explained assuming the presence of an internal field, possibly generated by charged defects, which can change its direction and magnitude under illumination, with consequence on the orientation and magnitude of the ferroelectric polarization, and on the sign/shape of the short-circuit photocurrent spectral distribution.
Magnetic properties and microstructure of graded Fe/FePt films
Authors: Tsai Jai-Lin , Tzeng Hsin-Te , Liu Bing-Fong
Published: June 2010

A soft/hard Fe/FePt bilayer with perpendicular magnetization was prepared on a glass substrate. Annealed Fe/FePt film allowed modification of the Fe/FePt sharp interface to Fe/(Fe-rich FePt)/FePt graded interface with rigid magnetization due to the nanoscale soft/hard interface coupling. The magnetization was reversed at a single switching field and interpreted by the two-spin model. When the annealed temperature of the Fe/FePt film increased, the remanence magnetization decreased continuously but the out-of-plane coercivity increased obviously at 600–700 °C which was interpreted by the graded magnetic anisotropy. The coercivity can be tuning in the exchange coupled composite film.
Electromigration-driven surface morphological stabilization of a coherently strained epitaxial thin film on a substrate
Authors: Sfyris Georgios I. , Gungor M. Rauf , Maroudas Dimitrios
Published: June 2010

We analyze the surface morphological stability of a coherently strained thin film grown epitaxially on a thick elastic substrate under the simultaneous action of an electric field that drives surface electromigration. A model of driven film surface morphological evolution is developed and a linear stability analysis is carried out of the planar film surface morphology. The analysis reveals that surface electromigration can inhibit surface morphological instabilities due to the lattice mismatch between the film and the substrate. The critical electric-field strength for surface stabilization and the optimal electric-field direction are determined and the effects of surface diffusional anisotropy are examined.
Room temperature ferromagnetism in pristine MgO thin films
Authors: Araujo C. Moyses , Kapilashrami Mukes , Jun Xu , Jayakumar O. D. , Nagar Sandeep , Wu Yan , Århammar Cecilia , Johansson Börje , Belova Lyubov , Ahuja Rajeev , Gehring Gillian A. , Rao K. V.
Published: June 2010

Robust ferromagnetic ordering at, and well above room temperature is observed in pure transparent MgO thin films (<170 nm thick) deposited by three different techniques. Careful study of the wide scan x-ray photoelectron spectroscopy rule out the possible presence of any magnetic contaminants. In the magnetron sputtered films, we observe magnetic phase transitions as a function of film thickness. The maximum saturation magnetization of 5.7 emu/cm3 is measured on a 170 nm thick film. The films above 500 nm are found to be diamagnetic. Ab initio calculations suggest that the ferromagnetism is mediated by cation vacancies.
Electrochemical control of quantum interference in anthraquinone-based molecular switches
Authors: Markussen Troels , Schiötz Jakob , Thygesen Kristian S.
Published: June 2010

Using first-principles calculations we analyze the electronic transport properties of a recently proposed anthraquinone-based electrochemical switch. Robust conductance on/off ratios of several orders of magnitude are observed due to destructive quantum interference present in the anthraquinone but absent in the hydroquinone molecular bridge. A simple explanation of the interference effect is achieved by transforming the frontier molecular orbitals into localized molecular orbitals thereby obtaining a minimal tight-binding model describing the transport in the relevant energy range in terms of hopping via the localized orbitals. The topology of the tight-binding model, which is dictated by the symmetries of the molecular orbitals, determines the amount of quantum interference.
The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization
Authors: Duffy R. , Shayesteh M. , White M. , Kearney J. , Kelleher A.-M.
Published: June 2010

Design and optimization of n-type doped regions in germanium by solid phase epitaxial recrystallization (SPER) have been studied by the authors. A systematic study is presented of process variables that influence activation and thermal stability, including preamorphization, coimplants, recrystallization temperature, and postrecrystallization thermal treatments. Unlike silicon, activation after recrystallization in germanium is not optimum where the postrecrystallization thermal budget is kept to a minimum. With the aid of modeling, a maximum peak activation of 7×1019 cm−3 was extracted. A steady increase in sheet resistance during postrecrystallization anneals confirms the formation of metastable activation by SPER. It is predicted that active concentrations of 6–8×1019 cm−3 are sufficient to meet targets for sub-20 nm technologies.
Effect of pelleting of concentrates on milk and blood selenium concentrations in lactating dairy cows when selenised yeast is included in the diet
Authors: Stockdale C. R. , Gill H. S.
Published: June 2010

An experiment using 12 multiparous Holstein–Friesian cows was undertaken for 3 weeks in September–October 2008 to determine milk and blood selenium (Se) concentrations (surrogates for bioavailability) when Se-yeast was incorporated into pellets relative to providing unprocessed Se-yeast. The Se in the Se-yeast is principally in the form of seleno-methionine. Since the bioavailability of protein can be reduced by heat processing, it was hypothesised that the temperature and/or pressure conditions associated with commercial pelleting of concentrates would adversely influence the Se concentrations in milk and blood by reducing the bioavailability of Se in the animal compared with Se-yeast that had not been subjected to pelleting. The results clearly showed that pelleting conditions had no effect on concentrations of either milk or blood Se, thereby indicating that pelleting did not have an impact on the bioavailability of the Se in the animal.
Effects of Yerba Mate (Ilex paraguariensis) supplementation on the performance of dairy calves
Authors: Celi Pietro , Robinson Adam
Published: June 2010

Yerba Mate (Ilex paraguariensis), a tea known for its high antioxidant content, was supplemented to 24 of 48 Holstein calves to assess its effect on the calves’ performance. Calves were weighed and blood samples were taken each week. Serum was assayed for metabolic parameters (total protein, albumin, urea, non-esterified fatty acids, triglycerides and β-hydroxybutyric acid) and markers of oxidative status [advanced oxidation protein products, 8-isoprostane and total antioxidant capacity (TAC) concentration]. Supplemented calves had higher triglyceride levels (P < 0.05) suggesting that Yerba Mate induced fat mobilisation and usage. A significant effect of the interaction time of sampling × diet (P < 0.05) was noted for plasma TAC concentration with the Yerba mate calves presenting significantly lower levels of TAC on the last week of the trial. Yerba Mate supplemented calves had significantly lower levels of total protein (P < 0.05) and albumin (P < 0.05) compared with the non-supplemented calves. The net result was reduced liveweight in Yerba Mate supplemented calves (P < 0.001) and thus the hypothesis that Yerba Mate supplementation would increase dairy calves’ growth rates was rejected. This study demonstrated that supplementation of Yerba Mate to dairy calves had significant effects on their metabolic and oxidative status, which resulted in lower liveweight at the end of the trial.
Proportion of rams and the condition of ewe lambs at joining influences their breeding performance
Authors: Kenyon P. R. , Morris S. T. , West D. M.
Published: June 2010

The aim of the present study was to examine the effects of ram : ewe lamb ratio and condition score on the reproductive performance of ewe lambs. In the 2007 study, ewe lambs were bred with rams, at ram : ewe lamb ratios of 1 : 30, 1 : 50, 1 : 75 or 1 : 100. In the 2008 study, ewe lambs were bred at ratios of 1 : 31, 1 : 50, 1 : 75 or 1 : 100. Ewe lambs were bred over two 17-day periods. In both studies, ewe lambs bred in the first 17 days of breeding only were heavier (P < 0.05) than those bred in the second 17-day period only, and those ewe lambs diagnosed as twin-bearing were heavier (P < 0.05) than their single-bearing counterparts. Ewe lambs with a condition score of 2.5 or greater were more likely (P < 0.05) to be bred, and be pregnant, in the first 17 days of breeding than those of condition score 1.5 or 2.0. Over the entire 34-day breeding period, ewe lambs with a condition score of 2.5 or greater had higher (P < 0.05) pregnancy rates than those with a condition score of 2.0, which in turn had higher rates than those of 1.5. In the 2007 study, after 34 days of breeding, there were no differences (P > 0.05) in pregnancy rates among the different ram : ewe lamb ratios. While in the 2008 study, pregnancy rates after 34 days were greater (P < 0.05) in the 1 : 50 compared with both the 1 : 75 and 1 : 100 treatments. Pregnancy rates of 1 : 31 ewe lambs were greater (P < 0.05) than those of 1 : 75 ewe lambs. In the 2007 study, pregnancy rates of ewe lambs to the first 17 days of breeding were greater (P < 0.05) for those bred at a ratio of 1 : 75 than for those bred at 1 : 50, and tended to be greater (P = 0.08) than for those bred at 1 : 100. In addition, those bred at a ratio of 1 : 30 tended to have higher pregnancy rates (P = 0.07) than those bred at 1 : 50. While in the 2008 study, pregnancy rates to the first 17 days of breeding were greatest (P < 0.05) in the 1 : 31 and 1 : 50 treatments groups. In conclusion, the results of the present study indicate that achieving greater liveweights and higher condition scores of ewe lambs at breeding will increase the proportion pregnant, especially early in the breeding period. The data also suggest, in combination with the results of previous research, that farmers should consider utilising ram : ewe lamb ratios lower than 1 : 100, although further studies are warranted.
Sustainable use of anthelmintics in an Integrated Parasite Management Program for sheep nematodes
Authors: Woodgate R. G. , Besier R. B.
Published: June 2010

Anthelmintic resistance is a major problem affecting sheep nematode control; however, chemical treatments will always be a likely routine part of any parasite control program. The present paper, with the aim of minimising the selection pressure for worsening anthelmintic resistance, outlines important practical and strategic aspects of planning the anthelmintic component of an integrated approach to sheep worm management.
Heterogeneous Connexin43 distribution in heart failure is associated with dispersed conduction and enhanced susceptibility to ventricular arrhythmias
Authors: Boulaksil Mohamed , Winckels Stephan K.G. , Engelen Markus A. , Stein Mèra , van Veen Toon A.B. , Jansen John A. , Linnenbank André C. , Bierhuizen Marti F.A. , Groenewegen W. Antoinette , van Oosterhout Matthijs F.M. , Kirkels Johannes H. , de Jonge Nicolaas , Varró András , Vos Marc A. , de Bakker Jacques M.T. , van Rijen Harold V.M.
Published: June 2010

Aims

Sudden arrhythmogenic cardiac death is a major cause of mortality in patients with congestive heart failure (CHF). To investigate determinants of the increased arrhythmogenic susceptibility, we studied cardiac remodelling and arrhythmogenicity in CHF patients and in a mouse model of chronic pressure overload.

Methods and results

Clinical and (immuno)histological data of myocardial biopsies from CHF patients with (VT+) and without (VT−) documented ventricular arrhythmia were compared with controls. In CHF patients, ejection fraction was decreased and QRS duration was increased. Cell size and interstitial fibrosis were increased, but Connexin43 (Cx43) levels, the most abundant gap junction in ventricular myocardium, were unchanged. No differences were found between VT+ and VT− patients, except for the distribution pattern of Cx43, which was significantly more heterogeneous in VT+. Mice were subjected to transverse aortic constriction (TAC) or sham operated. At 16 weeks, cardiac function was determined by echocardiography and epicardial ventricular activation mapping was performed. Transverse aortic constriction mice had decreased fractional shortening and prolonged QRS duration. Right ventricular conduction velocity was reduced, and polymorphic VTs were induced in 44% TAC and 0% sham mice. Interstitial fibrosis was increased and Cx43 quantity was unchanged in TAC mice with and without arrhythmias. Similar to CHF patients, heterogeneous Cx43 distribution was significantly associated with arrhythmias in TAC mice and with spatial heterogeneity of impulse conduction.

Conclusion

Heterogeneous Cx43 expression during CHF is associated with dispersed impulse conduction and may underlie enhanced susceptibility to ventricular tachyarrhythmias.
Transitional fossils and the origin of turtles
Authors: Lyson Tyler R. , Bever Gabe S. , Bhullar Bhart-Anjan S. , Joyce Walter G. , Gauthier Jacques A.
Published: June 2010

The origin of turtles is one of the most contentious issues in systematics with three currently viable hypotheses: turtles as the extant sister to (i) the crocodile–bird clade, (ii) the lizard–tuatara clade, or (iii) Diapsida (a clade composed of (i) and (ii)). We reanalysed a recent dataset that allied turtles with the lizard–tuatara clade and found that the inclusion of the stem turtle
Proganochelys quenstedti
and the ‘parareptile’
Eunotosaurus africanus
results in a single overriding morphological signal, with turtles outside Diapsida. This result reflects the importance of transitional fossils when long branches separate crown clades, and highlights unexplored issues such as the role of topological congruence when using fossils to calibrate molecular clocks.
Are snake populations in widespread decline?
Authors: Reading C. J. , Luiselli L. M. , Akani G. C. , Bonnet X. , Amori G. , Ballouard J. M. , Filippi E. , Naulleau G. , Pearson D. , Rugiero L.
Published: June 2010

Long-term studies have revealed population declines in fishes, amphibians, reptiles, birds and mammals. In birds, and particularly amphibians, these declines are a global phenomenon whose causes are often unclear. Among reptiles, snakes are top predators and therefore a decline in their numbers may have serious consequences for the functioning of many ecosystems. Our results show that, of 17 snake populations (eight species) from the UK, France, Italy, Nigeria and Australia, 11 have declined sharply over the same relatively short period of time with five remaining stable and one showing signs of a marginal increase. Although the causes of these declines are currently unknown, we suspect that they are multi-faceted (such as habitat quality deterioration, prey availability), and with a common cause, e.g. global climate change, at their root.
Morphological responses of a stream fish to water impoundment
Authors: Haas Travis C. , Blum Michael J. , Heins David C.
Published: June 2010

Water impoundment imposes fundamental changes on natural landscapes by transforming rivers into reservoirs. The dramatic shift in physical conditions accompanying the loss of flow creates novel ecological and evolutionary challenges for native species. In this study, we compared the body shape of
Cyprinella venusta
collected from eight pairs of river and reservoir sites across the Mobile River Basin (USA). Geometric morphometric analysis of the body shape showed that river populations differ from reservoir populations. Individuals inhabiting reservoirs are deep-bodied and have a smaller head, a more anterior dorsal fin, a shorter dorsal fin base and a more ventral position of the eye than
C. venusta
in streams. The direction of shape divergence within reservoir–river pairs was consistent among pairs of sites, and the shape of
C. venusta
in reservoirs is strongly correlated with reservoir size. These findings show that physical characteristics of reservoirs drive changes in the morphological attributes of native fish populations, indicating that water impoundment may be an important, yet largely unrecognized, evolutionary driver acting on aquatic biodiversity.
The evolvability of programmable hardware
Authors: Raman Karthik , Wagner Andreas
Published: June 2010

In biological systems, individual phenotypes are typically adopted by multiple genotypes. Examples include protein structure phenotypes, where each structure can be adopted by a myriad individual amino acid sequence genotypes. These genotypes form vast connected ‘neutral networks’ in genotype space. The size of such neutral networks endows biological systems not only with robustness to genetic change, but also with the ability to evolve a vast number of novel phenotypes that occur near any one neutral network. Whether technological systems can be designed to have similar properties is poorly understood. Here we ask this question for a class of programmable electronic circuits that compute digital logic functions. The functional flexibility of such circuits is important in many applications, including applications of evolutionary principles to circuit design. The functions they compute are at the heart of all digital computation. We explore a vast space of 1045logic circuits (‘genotypes’) and 1019logic functions (‘phenotypes’). We demonstrate that circuits that compute the same logic function are connected in large neutral networks that span circuit space. Their robustness or fault-tolerance varies very widely. The vicinity of each neutral network contains circuits with a broad range of novel functions. Two circuits computing different functions can usually be converted into one another via few changes in their architecture. These observations show that properties important for the evolvability of biological systems exist in a commercially important class of electronic circuitry. They also point to generic ways to generate fault-tolerant, adaptable and evolvable electronic circuitry.
Visualizing biointerfaces in three dimensions: electron tomography of the bone–hydroxyapatite interface
Authors: Grandfield K. , McNally E. A. , Palmquist A. , Botton G. A. , Thomsen P. , Engqvist H.
Published: June 2010

A positive interaction between human bone tissue and synthetics is crucial for the success of bone-regenerative materials. A greater understanding of the mechanisms governing bone-bonding is often gained via visualization of the bone–implant interface. Interfaces to bone have long been imaged with light, X-rays and electrons. Most of these techniques, however, only provide low-resolution or two-dimensional information. With the advances in modern day transmission electron microscopy, including new hardware and increased software computational speeds, the high-resolution visualization and analysis of three-dimensional structures is possible via electron tomography. We report, for the first time, a three-dimensional reconstruction of the interface between human bone and a hydroxyapatite implant using Z-contrast electron tomography. Viewing this structure in three dimensions enabled us to observe the nanometre differences in the orientation of hydroxyapatite crystals precipitated on the implant surfacein vivoversus those in the collagen matrix of bone. Insight into the morphology of biointerfaces is considerably enhanced with three-dimensional techniques. In this regard, electron tomography may revolutionize the approach to high-resolution biointerface characterization.
Genus age, provincial area and the taxonomic structure of marine faunas
Authors: Harnik Paul G. , Jablonski David , Krug Andrew Z. , Valentine James W.
Published: June 2010

Species are unevenly distributed among genera within clades and regions, with most genera species-poor and few species-rich. At regional scales, this structure to taxonomic diversity is generated via speciation, extinction and geographical range dynamics. Here, we use a global database of extant marine bivalves to characterize the taxonomic structure of climate zones and provinces. Our analyses reveal a general, Zipf–Mandelbrot form to the distribution of species among genera, with faunas from similar climate zones exhibiting similar taxonomic structure. Provinces that contain older taxa and/or encompass larger areas are expected to be more species-rich. Although both median genus age and provincial area correlate with measures of taxonomic structure, these relationships are interdependent, nonlinear and driven primarily by contrasts between tropical and extra-tropical faunas. Provincial area and taxonomic structure are largely decoupled within climate zones. Counter to the expectation that genus age and species richness should positively covary, diverse and highly structured provincial faunas are dominated by young genera. The marked differences between tropical and temperate faunas suggest strong spatial variation in evolutionary rates and invasion frequencies. Such variation contradicts biogeographic models that scale taxonomic diversity to geographical area.
Kinship affects investment by helpers in a cooperatively breeding bird
Authors: Nam Ki-Baek , Simeoni Michelle , Sharp Stuart P. , Hatchwell Ben J.
Published: June 2010

Helping behaviour in cooperative breeding systems has been attributed to kin selection, but the relative roles of direct and indirect fitness benefits in the evolution of such systems remain a matter of debate. In theory, helpers could maximize the indirect fitness benefits of cooperation by investing more in broods with whom they are more closely related, but there is little evidence for such fine-scale adjustment in helper effort among cooperative vertebrates. In this study, we used the unusual cooperative breeding system of the long-tailed tit
Aegithalos caudatus
to test the hypothesis that the provisioning effort of helpers was positively correlated with their kinship to broods. We first use pedigrees and microsatellite genotypes to characterize the relatedness between helpers and breeders from a 14 year field study. We used both pedigree and genetic approaches because long-tailed tits have access to pedigree information acquired through social relationships, but any fitness consequences will be determined by genetic relatedness. We then show using both pedigrees and genetic relatedness estimates that alloparental investment by helpers increases as their relatedness to the recipients of their care increases. We conclude that kin selection has played a critical role in moulding the investment decisions of helpers in this cooperatively breeding species.
Spatial interplay of plant competition and consumer foraging mediate plant coexistence and drive the invasion ratchet
Authors: Orrock John L. , Baskett Marissa L. , Holt Robert D.
Published: June 2010

Indirect effects may play an important role in structuring plant communities. Using a spatially explicit model of consumer foraging and plant competition, we demonstrate how the relationship between the spatial area over which plants compete and the spatial scale of consumer behaviour can determine the outcome of competition when one plant species provides a refuge for mobile consumers (i.e. refuge-mediated apparent competition). Once an initial population of the invader is established, complete invasion may be inevitable because of an ever-advancing invasion front ratchets forward driven by a feeding front of mobile consumers. Because the spatial extent of apparent competition determines the area available for colonization, consumers may also dictate the rate at which an invasion occurs. We find that, as long as refuge-mediated apparent competition is sufficiently localized, invasion is possible even in systems characterized by low overall levels of consumer pressure. Moreover, we show that a stable equilibrium can result in which both resident and invading plants coexist, suggesting that spatial heterogeneity created by refuge-mediated apparent competition may be important in mediating coexistence in plant communities. The spatial interplay of consumer behaviour and plant competition may be an underappreciated mechanism affecting the composition, diversity and spatial pattern of plant communities.
Heritable circadian period length in a wild bird population
Authors: Helm Barbara , Visser Marcel E.
Published: June 2010

Timing is essential, but circadian clocks, which play a crucial role in timekeeping, are almost unaddressed in evolutionary ecology. A key property of circadian clocks is their free-running period length (
τ
), i.e. the time taken for a full cycle under constant conditions. Under laboratory conditions, concordance of
τ
with the ambient light–dark cycle confers major fitness benefits, but little is known about period length and its implications in natural populations. We therefore studied natural variation of circadian traits in a songbird, the great tit (
Parus major
), by recording locomotor activity of 98 hand-raised, wild-derived individuals. We found, unexpectedly, that the free-running period of this diurnal species was significantly shorter than 24 h in constant dim light. We furthermore demonstrate, to our knowledge for the first time in a wild vertebrate, ample genetic variation and high heritability (
h
2
= 0.86 ± 0.24), implying that period length is potentially malleable by micro-evolutionary change. The observed, short period length may be a consequence of sexual selection, as offspring from extra-pair matings had significantly shorter free-running periods than their half-siblings from within-pair matings. These findings position circadian clocks in the ‘real world’ and underscore the value of using chronobiological approaches in evolutionary ecology. Evolutionary ecologists study variation and its fitness consequences, but often have difficulties relating behavioural variation to physiological mechanisms. The findings presented here open the possibility that properties of internal, circadian clocks affect performance in traits that are relevant to fitness and sexual selection.
Impact of vaccination and birth rate on the epidemiology of pertussis: a comparative study in 64 countries
Authors: Broutin H. , Viboud C. , Grenfell B. T. , Miller M. A. , Rohani P.
Published: June 2010

Bordetella pertussisinfection remains an important public health problem worldwide despite decades of routine vaccination. A key indicator of the impact of vaccination programmes is the inter-epidemic period, which is expected to increase with vaccine uptake if there is significant herd immunity. Based on empirical data from 64 countries across the five continents over the past 30–70 years, we document the observed relationship between the average inter-epidemic period, birth rate and vaccine coverage. We then use a mathematical model to explore the range of scenarios for duration of immunity and transmission resulting from repeat infections that are consistent with empirical evidence. Estimates of pertussis periodicity ranged between 2 and 4.6 years, with a strong association with susceptible recruitment rate, defined as birth rate × (1 − vaccine coverage). Periodicity increased by 1.27 years on average after the introduction of national vaccination programmes (95% CI: 1.13, 1.41 years), indicative of increased herd immunity. Mathematical models suggest that the observed patterns of pertussis periodicity are equally consistent with loss of immunity that is not as rapid as currently thought, or with negligible transmission generated by repeat infections. We conclude that both vaccine coverage and birth rate drive pertussis periodicity globally and that vaccination induces strong herd immunity effects. A better understanding of the role of repeat infections in pertussis transmission is critical to refine existing control strategies.
Optimal management of chronic graft‐versus‐host disease in children
Authors: Jacobsohn David A.
Published: June 2010

Chronic graft‐versus‐host disease (GVHD) is a major complication after allogeneic haematopoietic stem cell transplantation (HSCT). Not only is it the major cause of late mortality in HSCT patients, but it also accounts for significant morbidity. Much of the literature on chronic GVHD has focused on adults. Chronic GVHD is of major importance in children, especially since they have years to live following the complications of chronic GVHD and its therapy. The goal is to review incidence, manifestations, and therapies, especially when applicable to the paediatric population.
Analysis of the kinetics of band 3 diffusion in human erythroblasts during assembly of the erythrocyte membrane skeleton
Authors: Kodippili Gayani C. , Spector Jeff , Kang Grace E. , Liu Hui , Wickrema Amittha , Ritchie Ken , Low Philip S.
Published: June 2010

During definitive erythropoiesis, erythroid precursors undergo differentiation through multiple nucleated states to an enucleated reticulocyte, which loses its residual RNA/organelles to become a mature erythrocyte. Over the course of these transformations, continuous changes in membrane proteins occur, including shifts in protein abundance, rates of expression, isoform prominence, states of phosphorylation, and stability. In an effort to understand when assembly of membrane proteins into an architecture characteristic of the mature erythrocyte occurs, we quantitated the lateral diffusion of the most abundant membrane protein, band 3 (AE1), during each stage of erythropoiesis using single particle tracking. Analysis of the lateral trajectories of individual band 3 molecules revealed a gradual reduction in mobility of the anion transporter as erythroblasts differentiated. Evidence for this progressive immobilization included a gradual decline in diffusion coefficients as determined at a video acquisition rate of 120 frames/s and a decrease in the percentage of compartment sizes >100 nm. Because complete acquisition of the properties of band 3 seen in mature erythrocytes is not observed until circulating erythrocytes are formed, we suggest that membrane maturation involves a gradual and cooperative assembly process that is not triggered by the synthesis of any single protein.
Diagnostic value of outcome measures following allergen exposure in an environmental challenge chamber compared with natural conditions
Authors: Hohlfeld J. M. , Holland‐Letz T. , Larbig M. , Lavae‐Mokhtari M. , Wierenga E. , Kapsenberg M. , Van Ree R. , Krug N. , Bufe A.
Published: June 2010

Background
Efficacy testing of drugs in seasonal allergic rhinitis (SAR) is often disturbed by seasonal variations of environmental allergens, and assessment of onset and duration of action is hardly possible under natural conditions. Allergen provocation in an environmental challenge chamber (ECC) can be of added value in this respect. However, the specificity, sensitivity, and reproducibility of outcome measures under both settings are unclear.

Objective
The aim of this study was to investigate and compare the diagnostic value (specificity, sensitivity, and reproducibility) of clinical end‐points and biomarkers both following allergen provocation in an ECC and under natural conditions.

Methods
Sixty adult patients with SAR to grass and 60 healthy subjects were exposed twice to grass pollen in an ECC and observed twice during the pollen season. Symptoms, nasal flow, as well as exhaled and nasal nitric oxide (NO) were investigated.

Results
The total nasal symptom score (TNSS) in the ECC had the best reproducibility (intraclass correlation coefficient ICC=0.86) and sensitivity/specificity [area under receiver operating characteristic curve (AUC)=0.99] of all measures. Symptoms in season also had good sensitivity/specificity but were far less reproducible. Nasal flow in the ECC had good sensitivity/specificity but reproducibility was limited. NO measurements showed good reproducibility but sensitivity/specificity were limited, except for exhaled NO in season (AUC=0.75).

Conclusion
The high reproducibility and sensitivity/specificity in the ECC suggests that TNSS is a valuable outcome measure. While exhaled NO can be considered to monitor airway inflammation, nasal NO appears to be unspecific.

Cite this as: J. M. Hohlfeld, T. Holland‐Letz, M. Larbig, M. Lavae‐Mokhtari, E. Wierenga, M. Kapsenberg, R. van Ree, N. Krug and A. Bufe, Clinical & Experimental Allergy, 2010 (40) 998–1006.
Functional expression of granzyme B in human plasmacytoid dendritic cells: a role in allergic inflammation
Authors: Bratke K. , Nielsen J. , Manig F. , Klein C. , Kuepper M. , Geyer S. , Julius P. , Lommatzsch M. , Virchow J. C.
Published: June 2010

Background
Plasmacytoid dendritic cells (pDCs) are involved in a variety of immune functions. However, the expression of cytotoxic granule proteins like granzymes and perforin in human pDCs is still poorly understood.

Objective
The aim of this study was to systematically analyse the expression and regulation of cytotoxic granule proteins in human pDCs.

Methods
The expression of cytotoxic proteins was analysed by RT‐PCR, flow cytometry, and fluorescence microscopy. The functional expression of these proteins was confirmed in a flow‐cytometry‐based cytotoxicity assay using K562 cells as targets. In order to analyse the regulation of pDC‐derived cytotoxic proteins in infectious and allergic diseases, human pDCs were analysed after stimulation with toll‐like receptor (TLR)7/9 ligands and in the human asthma model of segmental allergen challenge.

Results
Granzyme B (GrB), but not the granzymes A, H, K, M or perforin, was specifically expressed by human pDCs and this GrB expression was up‐regulated by IL‐3 stimulation. In addition, IL‐3‐stimulated pDCs were found to kill K562 cells in a GrB‐ and caspase‐dependent manner. TLR7/9 ligands significantly suppressed GrB expression in pDCs. In contrast, there was an up‐regulation of GrB in endobronchial pDCs 24 h after allergen challenge, and this was accompanied by enhanced GrB concentrations in bronchoalveolar lavage fluid.

Conclusion
We report the selective expression of GrB in human pDCs and show for the first time pDC‐mediated GrB‐ and caspase‐dependent cytotoxicity against target cells. In addition, the regulation of GrB expression was investigated in vitro and in vivo providing an evidence for a specific role of pDC‐derived GrB in allergic inflammation.

Cite this as: K. Bratke, J. Nielsen, F. Manig, C. Klein, M. Kuepper, S. Geyer, P. Julius, M. Lommatzsch and J. C. Virchow, Clinical & Experimental Allergy, 2010 (40) 1015–1024.
The role of filaggrin in the atopic diathesis
Authors: O'Regan G. M. , Irvine A. D.
Published: June 2010

Atopic dermatitis (AD) is an inflammatory disease characterized by pruritic skin lesions, immunodysregulation, disrupted epidermal barrier function and IgE‐mediated sensitization to food and environmental allergens. Identification of the aetiology of AD has become increasingly a priority, as it is clear that the disease burden exceeds AD alone, with many children suffering severe, multi‐system and occasionally life‐threatening allergic disease. Previous approaches to understanding AD have centred on mechanisms in the adaptive immune system, often with an emphasis on the Th1–Th2 paradigm. Recently, the conceptual focus has increasingly shifted to include a primary defect in the epithelial barrier as a threshold event in moderate‐to‐severe AD. Familial aggregation of the disease is well established through many family studies of AD, asthma and allergic rhinitis, suggesting a significant heritable component. The identification of loss‐of‐function mutations in the filaggrin (FLG) gene, whose product is a key structural protein in the outermost layer of the epidermis in up to 50% of patients with AD, provides a significant insight into explaining disease initiation and points to a complex secondary interplay of environmental and immunological sequelae once barrier disruption is established. The elucidation of the environmental, genetic and immunobiological modifiers of this structural molecule may also direct our understanding of the pathomechanisms and endotypes central to the atopic diathesis. The recent identification of a murine model for FLG‐AD, with the detection of a homozygous frame‐shift mutation in the Flg gene in flaky‐tail (ft/ft) mice, stands to rapidly accelerate our understanding of mechanisms and therapeutic intervention points in AD. Refining the molecular understanding of AD and its subtypes will allow for specific diagnostic, treatment and ultimately, preventative algorithms, and has opened an exciting new world of investigative challenges and collaborations.

Cite this as: G. M. O'Regan and A. D. Irvine, Clinical & Experimental Allergy, 2010 (40) 965–972.
Monitoring the effect of allergen immunotherapy: a clinician's dream comes true?
Authors: Bullens D. M. A.
Published: June 2010

Cite this as: D. M. A. Bullens, Clinical & Experimental Allergy, 2010 (40) 958–961.
Conjugated linoleic acid improves airway hyper‐reactivity in overweight mild asthmatics
Authors: MacRedmond R. , Singhera G. , Attridge S. , Bahzad M. , Fava C. , Lai Y. , Hallstrand T. S. , Dorscheid D. R.
Published: June 2010

Background
Conjugated linoleic acids (CLA) are naturally occurring fatty acids that have multiple biological properties including the regulation of metabolic, proliferative and immune processes.

Objective
The aim of this study was to investigate the efficacy and safety of CLA as a dietary supplement in mild asthma.

Methods
This was a prospective, randomized, double‐blind, placebo‐controlled study. Twenty‐eight adult subjects (aged 19–40 years) with mild asthma (FEV1>70% predicted) were randomized to CLA 4.5 g/day or placebo for 12 weeks in addition to usual treatment. On average, subjects were overweight with a mean body mass index (BMI) of 27.9 kg/m2.

Results
Subjects in the CLA group had a significant improvement in airway hyperresponsiveness (AHR) at week 12 compared with week 0 [PC20 6.6 (2.1) mg/mL vs. 2.2 (0.7) mg/mL; P<0.05]. The CLA group had a significant reduction in weight and BMI compared with placebo and this was associated with a reduction in leptin/adiponectin ratio. There were no differences in systemic cytokine levels, induced sputum cell counts, quality‐of‐life scores or adverse events.

Conclusions
CLA treatment as an adjunct to usual care in overweight mild asthmatics was well tolerated and was associated with improvements in AHR and BMI.

Cite this as: R. MacRedmond, G. Singhera, S. Attridge, M. Bahzad, C. Fava, Y. Lai, T. S. Hallstrand and D. R. Dorscheid, Clinical & Experimental Allergy, 2010 (40) 1071–1078.
Floodplain fisheries as natural insurance for the rural poor in tropical forest environments: evidence from Amazonia
Authors: COOMES O. T. , TAKASAKI Y. , ABIZAID C. , BARHAM B. L.
Published: June 2010

Abstract  The findings of livelihood research on the role of artisanal fishing among rain forest communities in eastern Peru are reported. In‐depth household surveys conducted in three communities along the Ucayali River (n = 68 households) and four communities on the Marañón River (n = 87) provided data on resource use, income generation, asset holdings and household coping strategies in the face of two common shocks – illness and major floods. Results indicated the high economic importance of artisanal fishing, with considerable specialisation evident in fishing at the household and community levels. When faced with adversity, forest people in the Upper Amazon turn more to the floodplain (to fish) than to the rain forest (to hunt or extract forest products) to cope with major shocks. It appears that floodplain fisheries are an important safety net for forest people living along rivers in humid tropical environments.
Activity‐dependent localization in spines of the F‐actin capping protein CapZ screened in a rat model of dementia
Authors: Kitanishi Takuma , Sakai Jun , Kojima Shinichi , Saitoh Yoshito , Inokuchi Kaoru , Fukaya Masahiro , Watanabe Masahiko , Matsuki Norio , Yamada Maki K.
Published: June 2010

Actin reorganization in dendritic spines is hypothesized to underlie neuronal plasticity. Actin‐related proteins, therefore, might serve as useful markers of plastic changes in dendritic spines. Here, we utilized memory deficits induced by fimbria‐fornix transection (FFT) in rats as a dementia model to screen candidate memory‐associated molecules by using a two‐dimensional gel method. Comparison of protein profiles between the transected and control sides of hippocampi after unilateral FFT revealed a reduction in the F‐actin capping protein (CapZ) signal on the FFT side. Subsequent immunostaining of brain sections and cultured hippocampal neurons revealed that CapZ localized in dendritic spines and the signal intensity in each spine varied widely. The CapZ content decreased after suppression of neuronal firing by tetrodotoxin treatment in cultured neurons, indicating rapid and activity‐dependent regulation of CapZ accumulation in spines. To test input specificity of CapZ accumulation in vivo, we delivered high‐frequency stimuli to the medial perforant path unilaterally in awake rats. This path selectively inputs to the middle molecular layer of the dentate gyrus, where CapZ immunoreactivity increased. We conclude that activity‐dependent, synapse‐specific regulation of CapZ redistribution might be important in both maintenance and remodeling of synaptic connections in neurons receiving specific spatial and temporal patterns of inputs.