bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of high-temperature dynamic crossover in protein hydration water and its relation to reversible denaturation of lysozyme
Authors: Zhang Yang , Lagi Marco , Liu Dazhi , Mallamace Francesco , Fratini Emiliano , Baglioni Piero , Mamontov Eugene , Hagen Mark , Chen Sow-Hsin
Published: April 2009

The diffusive dynamics of hydration water in lysozyme is studied by high-resolution incoherent quasielastic neutron scattering spectroscopy and molecular dynamics (MD) simulations in a temperature range of 290 K<T<380 K. The hydration level of the protein powder sample is kept at h=0.35 gram of water per gram of dry protein to provide monolayer of water coverage on the protein surfaces. Two lysozyme samples, the H2O hydrated and the D2O hydrated, are measured in the experiments. The difference spectra of the two are used to extract the diffusive dynamics of the hydration water. The self-diffusion constant D of the hydration water is obtained from the analyses of the low-Q spectra. The Arrhenius plot of the inverse diffusion constant [i.e., log(1/D) versus 1/T] shows a dynamic crossover from a super-Arrhenius behavior at low temperatures to an Arrhenius behavior at high temperatures bordered at TD=345±5 K. We also observe a pronounced increase in the migration distance d of the hydration water molecules above TD. We present evidence from the neutron scattering experiment that this dynamic crossover temperature in the hydration water coincides with that of the reversible denaturation of lysozyme determined by specific heat measurements. We further performed MD simulations of hydrated lysozyme powder to offer a plausible reason for this coincidence of the crossover phenomenon with the reversible denaturation of the protein.
Microwave shielding of fluorine-doped tin oxide film obtained by spray pyrolysis studied by electrical characterization
Authors: Rubinger C. P. L , da Cunha A. F. , Vinagre F. , Ribeiro G. M. , Costa L. C.
Published: April 2009

In this work, we report dc conductivity and Hall effect results for glasses coated with commercial In2O3:Sn and SnO2:F. Van der Pauw Hall effect and resistivity measurements were used to carry out the sheet resistance of the samples and to determine their carrier density, mobility, and conductivity from 10 to 325 K. We calculated the transmission from the dc measurements and compared it with the microwave response of a typical microwave oven door used as a barrier on a cavity resonator, at 2.8 GHz. By controlling the oxygen doping through the H2O amount in the solution, we were able to increase the mobility of SnO2:F sample and as a consequence obtained an improved microwave shielding power. We estimated that, for the best case, a coating 13.2 μm thick should suffice for a shielding power similar to that of a microwave oven door.
Effects of charged dust particles on nonlinear ion acoustic solitary waves in a relativistic plasma
Authors: Choi C.-R. , Lee D.-Y. , Kim Y.-H. , Lee Nam C.
Published: April 2009

Effects of dust charges on the nonlinear ion acoustic solitary waves in a fully relativistic dusty plasma for both cases of negative and positive dusts are numerically studied based on the pseudopotential method. In the presence of dusty particles, it is found that various types of nonlinear acoustic waves exist in forms which can be viewed as sequential combinations of three kinds of elementary solitary waves: bump, dip, and kink-type solitary waves. The number and the sequence of the constituent elementary solitary waves in a given nonlinear waves depend more sensitively on dust particle density than any other parameters. For negatively charged dust particles of low density, the nonlinear wave is in the shape of bumpy solitary wave. For a somewhat higher density, the wave changes into a form which can be viewed as a combination of bump and dip-type solitary waves. As the density is increased further, a more complex nonlinear wave composed of bump, kink, and dip-type solitary waves emerges. For a much higher density of dust particle, the nonlinear wave can have a shape that can be considered as a combination of bump and kink-type solitary waves. For the case of positively charged dust particles, two kinds of nonlinear waves can exist: bump-type solitary wave and a combination of bump and kink solitary waves. For both cases of negative and positive dust particles, it is found that single dip-type solitary wave does not exist. It is also found that as dust particle density increases, the signature of the elementary waves becomes less prominent.
Coexistence of superparamagnetic and superspin glass behaviors in Co50Ni50 nanoparticles embedded in the amorphous SiO2 host
Authors: Thakur M. , Patra M. , Majumdar S. , Giri S.
Published: April 2009

We investigate the magnetic properties of the nanoparticles of Co50Ni50 alloy embedded in the amorphous SiO2 host with volume fractions, ϕ=5% and 10%. The static and dynamic aspects of the magnetic properties are investigated by temperature and time dependence of low-field dc magnetization and frequency dependence of ac susceptibilities. The experimental results and analyses suggest that the dilution of the Co50Ni50 nanoparticles belongs to the crossover regime from superparamagnetic to superspin glass states, which are distinguished from the atomic canonical spin glasses.
Nonwetting of impinging droplets on textured surfaces
Authors: Deng Tao , Varanasi Kripa K. , Hsu Ming , Bhate Nitin , Keimel Chris , Stein Judith , Blohm Margaret
Published: April 2009

This paper studies the impinging droplets on superhydrophobic textured surfaces and proposes a design guideline for nonwetting surfaces under droplet impingement. A new wetting pressure, the effective water hammer pressure, is introduced in the study to clearly define wetting states for the impinging droplets. This approach establishes the design criteria for nonwetting surfaces to impinging droplets. For impingement speed higher than raindrop speed, the surfaces need to have sub-100-nm features to generate a large enough antiwetting pressure for the droplets to take a nonwetting state after impingement.
Interchanging Interactive 3D Graphics for Astronomy
Authors: Fluke C. J. , Barnes D. G. , Jones N. T.
Published: April 2009

We demonstrate how interactive, three-dimensional (3D) scientific visualizations can be efficiently interchanged between a variety of mediums. Through the use of an appropriate interchange format, and a unified interaction interface, we minimize the effort to produce visualizations appropriate for undertaking knowledge discovery at the astronomer's desktop, as part of conference presentations, in digital publications or as Web content. We use examples from cosmological visualization to address some of the issues of interchange and to describe our approach to adapting s2plot desktop visualizations to the Web2.
Activation of antibacterial autophagy by NADPH oxidases
Authors: Huang Ju , Canadien Veronica , Lam Grace Y. , Steinberg Benjamin E. , Dinauer Mary C. , Magalhaes Marco A. O. , Glogauer Michael , Grinstein Sergio , Brumell John H.
Published: April 2009

Autophagy plays an important role in immunity to microbial pathogens. The autophagy system can target bacteria in phagosomes, promoting phagosome maturation and preventing pathogen escape into the cytosol. Recently, Toll-like receptor (TLR) signaling from phagosomes was found to initiate their targeting by the autophagy system, but the mechanism by which TLR signaling activates autophagy is unclear. Here we show that autophagy targeting of phagosomes is not exclusive to those containing TLR ligands. Engagement of either TLRs or the Fcγ receptors (FcγRs) during phagocytosis induced recruitment of the autophagy protein LC3 to phagosomes with similar kinetics. Both receptors are known to activate the NOX2 NADPH oxidase, which plays a central role in microbial killing by phagocytes through the generation of reactive oxygen species (ROS). We found that NOX2-generated ROS are necessary for LC3 recruitment to phagosomes. Antibacterial autophagy in human epithelial cells, which do not express NOX2, was also dependent on ROS generation. These data reveal a coupling of oxidative and nonoxidative killing activities of the NOX2 NADPH oxidase in phagocytes through autophagy. Furthermore, our results suggest a general role for members of the NOX family in regulating autophagy.
A black body absorber from vertically aligned single-walled carbon nanotubes
Authors: Mizuno Kohei , Ishii Juntaro , Kishida Hideo , Hayamizu Yuhei , Yasuda Satoshi , Futaba Don N. , Yumura Motoo , Hata Kenji
Published: April 2009

Among all known materials, we found that a forest of vertically aligned single-walled carbon nanotubes behaves most similarly to a black body, a theoretical material that absorbs all incident light. A requirement for an object to behave as a black body is to perfectly absorb light of all wavelengths. This important feature has not been observed for real materials because materials intrinsically have specific absorption bands because of their structure and composition. We found a material that can absorb light almost perfectly across a very wide spectral range (0.2–200 μm). We attribute this black body behavior to stem from the sparseness and imperfect alignment of the vertical single-walled carbon nanotubes.
The scaling of green space coverage in European cities
Authors: Fuller Richard A. , Gaston Kevin J.
Published: April 2009

Most people on the planet live in dense aggregations, and policy directives emphasize green areas within cities to ameliorate some of the problems of urban living. Benefits of urban green spaces range from physical and psychological health to social cohesion, ecosystem service provision and biodiversity conservation. Green space coverage differs enormously among cities, yet little is known about the correlates or geography of this variation. This is important because urbanization is accelerating and the consequences for green space are unclear. Here, we use standardized major axis regression to explore the relationships between urban green space coverage, city area and population size across 386 European cities. We show that green space coverage increases more rapidly than city area, yet declines only weakly as human population density increases. Thus, green space provision within a city is primarily related to city area rather than the number of inhabitants that it serves, or a simple space-filling effect. Thus, compact cities (small size and high density) show very lowper capitagreen space allocation. However, at high levels of urbanicity, the green space network is robust to further city compaction. As cities grow, interactions between people and nature depend increasingly on landscape quality outside formal green space networks, such as street plantings, or the size, composition and management of backyards and gardens.
New frontiers in biologging science
Authors: Rutz Christian , Hays Graeme C.
Published: April 2009

The term ‘biologging’ refers to the use of miniaturized animal-attached tags for logging and/or relaying of data about an animal's movements, behaviour, physiology and/or environment. Biologging technology substantially extends our abilities to observe, and take measurements from, free-ranging, undisturbed subjects, providing much scope for advancing both basic and applied biological research. Here, we review highlights from the third international conference on biologging science, which was held in California, USA, from 1 to 5 September 2008. Over the last few years, considerable progress has been made with a range of recording technologies as well as with the management, visualization, integration and analysis of increasingly large and complex biologging datasets. Researchers use these techniques to study animal biology with an unprecedented level of detail and across the full range of ecological scales—from the split-second decision making of individuals to the long-term dynamics of populations, and even entire communities. We conclude our report by suggesting some directions for future research.
Nanoparticles of a different source induce different patterns of activation in key biochemical and cellular components of the host response
Authors: Guildford A.L. , Poletti T. , Osbourne L.H. , Di Cerbo A. , Gatti A.M. , Santin M.
Published: April 2009

Nanoparticulate materials are produced by industrial processing or engineered for specific biomedical applications. In both cases, their contact with the human body may lead to adverse reactions. Most of the published papers so far have focused on the cytotoxic effects of nanoparticles (NPs). Instead, the present
in vitro
study investigates the effect of different types of NP on key components of the host response such as clot formation and the inflammatory cells. The different NPs were pre-conditioned with platelet-rich human plasma for 30 min and then incubated with the blood mononuclear cells for 20 hours. The potential of the different NPs to induce clot formation, platelet activation and monocyte/macrophage differentiation was assessed by morphological analysis, immunocytochemistry and biochemical assays. The data showed that nanoparticulate materials based on antimony, silver and nickel were capable of promoting the polymerization of fibrin and the aggregation and fragmentation of platelets, leading to a moderately activated monocyte phenotype. This process was more pronounced in the case of antimony- and silver-based NPs that share a similar size and round-shaped morphology. Conversely, NPs of cobalt, titanium and iron appeared to stimulate cells to acquire a macrophage phenotype able to secrete higher levels of tumour necrosis factor α, a pro-inflammatory cytokine. Therefore, the present study provides clear indications about the subtle and adverse effects that the invasion of these materials may produce in the cardiovascular system and in vital organs.
Control of equine influenza: scenario testing using a realistic metapopulation model of spread
Authors: Baguelin M. , Newton J. R. , Demiris N. , Daly J. , Mumford J. A. , Wood J. L. N.
Published: April 2009

We present a metapopulation model of the spread of equine influenza among thoroughbred horses parametrized with data from a 2003 outbreak in Newmarket, UK. The number of horses initially susceptible is derived from a threshold theorem and a published statistical model. Two simulated likelihood-based methods are used to find the within- and between-yard transmissions using both exponential and empirical latent and infectious periods. We demonstrate that the 2003 outbreak was largely locally driven and use the parametrized model to address important questions of control. The chance of a large epidemic is shown to be largely dependent on the size of the index yard. The impact of poor responders to vaccination is estimated under different scenarios. A small proportion of poor responders strongly influences the efficiency of vaccine policies, which increases risk further when the vaccine and infecting strains differ following antigenic drift. Finally, the use of vaccinating in the face of an outbreak is evaluated at a global and individual management group level. The benefits for an individual horse trainer are found to be substantial, although this is influenced by the behaviour of other trainers.
Windows on a Lilliputian world: a personal perspective on the development of electron microscopy in the twentieth century
Authors: Andrews Elizabeth B.
Published: April 2009

The early development and blossoming of electron microscopy in the twentieth century are outlined with particular reference to biological applications, and the establishment and demise of facilities for the Faculty of Science in a London college are charted in relation to funding, staffing, and economic pressures. Use of these facilities for research, teaching and the promotion of science declined as the pressure to maximize outside income increased.
Non-traditional ligands in f-block chemistry
Authors: Liddle Stephen T.
Published: April 2009

The molecular chemistry of the f-elements, i.e. the lanthanides and actinides, is traditionally dominated by the use of carbon, nitrogen, oxygen or halide ligands. However, the use of metal-based fragments as ligands is underdeveloped, which contrasts to the field of d-block metal–metal complexes that have developed extensively over the last 50 years. Consequently, the use of metal-based fragments as ligands to the f-elements may be regarded as ‘non-traditional’. This review outlines the development of compounds that possess f-element–metal bonds that may be described as polarized covalent or donor–acceptor in nature. For this review, the f-element is defined as (i) a group 3 or lanthanide metal: scandium, yttrium and lanthanum to lutetium or (ii) an actinide metal: thorium or uranium, and the metal is defined as a d-block transition metal, or a p-block triel (group 13, aluminium or gallium), a tetrel (group 14, silicon, germanium or tin), or a pnictide (group 15, antimony or bismuth) metal. Silicon, germanium and antimony are traditionally classified as metalloids, but we include them in this review for completeness. This review focuses on complexes that have been unambiguously structurally authenticated by single crystal X-ray diffraction studies, and novel aspects of their syntheses, properties and reactivities are highlighted.
Losses of female song with changes from tropical to temperate breeding in the New World blackbirds
Authors: Price J. Jordan , Lanyon Scott M. , Omland Kevin E.
Published: April 2009

Birds in which both sexes produce complex songs are thought to be more common in the tropics than in temperate areas, where typically only males sing. Yet the role of phylogeny in this apparent relationship between female song and latitude has never been examined. Here, we reconstruct evolutionary changes in female song and breeding latitude in the New World blackbirds (Icteridae), a family with both temperate and tropical representatives. We provide strong evidence that members of this group have moved repeatedly from tropical to temperate breeding ranges and, furthermore, that these range shifts were associated with losses of female song more often than expected by chance. This historical perspective suggests that male-biased song production in many temperate species is the result not of sexual selection for complex song in males but of selection against such songs in females. Our results provide new insights into the differences we see today between tropical and temperate songbirds, and suggest that the role of sexual selection in the evolution of bird song might not be as simple as we think.
Ecological selection pressures for C4photosynthesis in the grasses
Authors: Osborne Colin P. , Freckleton Robert P.
Published: April 2009

Grasses using the C4photosynthetic pathway dominate grasslands and savannahs of warm regions, and account for half of the species in this ecologically and economically important plant family. The C4pathway increases the potential for high rates of photosynthesis, particularly at high irradiance, and raises water-use efficiency compared with the C3type. It is therefore classically viewed as an adaptation to open, arid conditions. Here, we test this adaptive hypothesis using the comparative method, analysing habitat data for 117 genera of grasses, representing 15 C4lineages. The evidence from our three complementary analyses is consistent with the hypothesis that evolutionary selection for C4photosynthesis requires open environments, but we find an equal likelihood of C4evolutionary origins in mesic, arid and saline habitats. However, once the pathway has arisen, evolutionary transitions into arid habitats occur at higher rates in C4than C3clades. Extant C4genera therefore occupy a wider range of drier habitats than their C3counterparts because the C4pathway represents a pre-adaptation to arid conditions. Our analyses warn against evolutionary inferences based solely upon the high occurrence of extant C4species in dry habitats, and provide a novel interpretation of this classic ecological association.
Reactive oxygen species as universal constraints in life-history evolution
Authors: Dowling Damian K. , Simmons Leigh W.
Published: April 2009

Evolutionary theory is firmly grounded on the existence of trade-offs between life-history traits, and recent interest has centred on the physiological mechanisms underlying such trade-offs. Several branches of evolutionary biology, particularly those focusing on ageing, immunological and sexual selection theory, have implicated reactive oxygen species (ROS) as profound evolutionary players. ROS are a highly reactive group of oxygen-containing molecules, generated as common by-products of vital oxidative enzyme complexes. Both animals and plants appear to intentionally harness ROS for use as molecular messengers to fulfil a wide range of essential biological processes. However, at high levels, ROS are known to exert very damaging effects through oxidative stress. For these reasons, ROS have been suggested to be important mediators of the cost of reproduction, and of trade-offs between metabolic rate and lifespan, and between immunity, sexual ornamentation and sperm quality. In this review, we integrate the above suggestions into one life-history framework, and review the evidence in support of the contention that ROS production will constitute a primary and universal constraint in life-history evolution.
Inducible defences as key adaptations for the successful invasion ofDaphnia lumholtziin North America?
Authors: Engel Katharina , Tollrian Ralph
Published: April 2009

The mechanisms underlying successful biological invasions often remain unclear. In the case of the tropical water fleaDaphnia lumholtzi, which invaded North America, it has been suggested that this species possesses a high thermal tolerance, which in the course of global climate change promotes its establishment and rapid spread. However,D. lumholtzihas an additional remarkable feature: it is the only water flea that forms rigid head spines in response to chemicals released in the presence of fishes. These morphologically (phenotypically) plastic traits serve as an inducible defence against these predators. Here, we show in controlled mesocosm experiments that the native North American speciesDaphnia pulicariais competitively superior toD. lumholtziin the absence of predators. However, in the presence of fish predation the invasive species formed its defences and became dominant. This observation of a predator-mediated switch in dominance suggests that the inducible defence against fish predation may represent a key adaptation for the invasion success ofD. lumholtzi.
Can fertility signals lead to quality signals? Insights from the evolution of primate sexual swellings
Authors: Huchard Elise , Courtiol Alexandre , Benavides Julio A. , Knapp Leslie A. , Raymond Michel , Cowlishaw Guy
Published: April 2009

The sexual swellings of female primates have generated a great deal of interest in evolutionary biology. Two hypotheses recently proposed to elucidate their functional significance argue that maximal swelling size advertises either female fertility within a cycle or female quality across cycles. Published evidence favours the first hypothesis, and further indicates that larger swellings advertise higher fertility between cycles. If so, a male preference for large swellings might evolve, driving females to use swellings as quality indicators, as proposed by the second hypothesis. In this paper, we explore this possibility using a combination of empirical field data and mathematical modelling. We first test and find support for three key predictions of the female-quality hypothesis in wild chacma baboons (
Papio ursinus
): (i) inter-individual differences in swelling size are maintained across consecutive cycles, (ii) females in better condition have larger swellings and higher reproductive success, and (iii) males preferentially choose females with large swellings. We then develop an individual-based simulation model that indicates that females producing larger swellings can achieve higher mating success even when female–female competition is low and within-female variance in the trait is high. Taken together, our findings show that once sexual swellings have evolved as fertility signals, they might, in certain socio-sexual systems, be further selected to act as quality signals. These results, by reconciling two hypotheses, help to clarify the processes underlying sexual swelling evolution. More generally, our findings suggest that mate choice for direct benefits (fertility) can lead to indirect benefits (good genes).
Fine-tuned modulation of competitive behaviour according to kinship in barn swallow nestlings
Authors: Boncoraglio Giuseppe , Caprioli Manuela , Saino Nicola
Published: April 2009

Kin selection theory predicts that, in species where progeny members compete for limiting parental care, individual offspring should be more prone to monopolize parental resources as their genetic relatedness to brood competitors decreases. Mixed parentage among broodmates may arise as a consequence, for example, of extra-pair fertilization or brood parasitism events. In this experimental study of barn swallows (Hirundo rustica), we reciprocally partially cross-fostered hatchlings between broods and compared the behaviour of pairs of related and unrelated broodmates in a competitive context, both under normal food provisioning regime and after mild food deprivation. We found that scramble competition for food mediated by visual and vocal solicitation displays (begging) is inversely related to relatedness among competitors, independent of their level of satiation. Nestlings may modulate their competitive behaviour according to vocal cues that vary with their origin and allow kin recognition. We also uncover direct fitness costs to both parents and offspring arising from mixed parentage in a brood, in terms of increased parental workload and reduced survival of the nestlings. Such previously neglected costs may select for reduced frequency of extra-pair fertilizations and brood parasitism in species with extensive parental care.
Sexual selection drives weak positive selection in protamine genes and high promoter divergence, enhancing sperm competitiveness
Authors: Martin-Coello Juan , Dopazo Hernán , Arbiza Leonardo , Ausió Juan , Roldan Eduardo R.S. , Gomendio Montserrat
Published: April 2009

Phenotypic adaptations may be the result of changes in gene structure or gene regulation, but little is known about the evolution of gene expression. In addition, it is unclear whether the same selective forces may operate at both levels simultaneously. Reproductive proteins evolve rapidly, but the underlying selective forces promoting such rapid changes are still a matter of debate. In particular, the role of sexual selection in driving positive selection among reproductive proteins remains controversial, whereas its potential influence on changes in promoter regions has not been explored. Protamines are responsible for maintaining DNA in a compacted form in chromosomes in sperm and the available evidence suggests that they evolve rapidly. Because protamines condense DNA within the sperm nucleus, they influence sperm head shape. Here, we examine the influence of sperm competition upon protamine 1 and protamine 2 genes and their promoters, by comparing closely related species ofMusthat differ in relative testes size, a reliable indicator of levels of sperm competition. We find evidence of positive selection in the protamine 2 gene in the species with the highest inferred levels of sperm competition. In addition, sperm competition levels across all species are strongly associated with high divergence in protamine 2 promoters that, in turn, are associated with sperm swimming speed. We suggest that changes in protamine 2 promoters are likely to enhance sperm swimming speed by making sperm heads more hydrodynamic. Such phenotypic changes are adaptive because sperm swimming speed may be a major determinant of fertilization success under sperm competition. Thus, when species have diverged recently, few changes in gene-coding sequences are found, while high divergence in promoters seems to be associated with the intensity of sexual selection.
Quantitative Genetic Analysis of Thermal Dissipation in Arabidopsis
Authors: Jung Hou-Sung , Niyogi Krishna K.
Published: April 2009

Feedback deexcitation is a photosynthetic regulatory mechanism that can protect plants from high light stress by harmlessly dissipating excess absorbed light energy as heat. To understand the genetic basis for intraspecies differences in thermal dissipation capacity, we investigated natural variation in Arabidopsis (Arabidopsis thaliana). We determined the variation in the amount of thermal dissipation by measuring nonphotochemical quenching (NPQ) of chlorophyll fluorescence in Arabidopsis accessions of diverse origins. Ll-1 and Sf-2 were selected as high NPQ Arabidopsis accessions, and Columbia-0 (Col-0) and Wassilewskija-2 were selected as relatively low NPQ accessions. In spite of significant differences in NPQ, previously identified NPQ factors were indistinguishable between the high and the low NPQ accessions. Intermediate levels of NPQ in Ll-1 × Col-0 F1 and Sf-2 × Col-0 F1 compared to NPQ levels in their parental lines and continuous distribution of NPQ in F2 indicated that the variation in NPQ is under the control of multiple nuclear factors. To identify genetic factors responsible for the NPQ variation, we developed a polymorphic molecular marker set for Sf-2 × Col-0 at approximately 10-centimorgan intervals. From quantitative trait locus (QTL) mapping with undistorted genotype data and NPQ measurements in an F2 mapping population, we identified two high NPQ QTLs, HQE1 (high qE 1, for high energy-dependent quenching 1) and HQE2, on chromosomes 1 and 2, and the phenotype of HQE2 was validated by analysis of near isogenic lines. Neither QTL maps to a gene that had been identified previously in extensive forward genetics screens using induced mutants, suggesting that quantitative genetics can be used to find new genes affecting thermal dissipation.
High-performance compact-multi-crystal analyzer for X-ray diffractometer scans
Authors: Toraya Hideo
Published: April 2009

A new high-performance diffracted-beam analyzer consisting of multiple pieces of a perfect crystal is proposed. The pieces of Ge(111) crystal are set so that their crystal lattice planes coincide with tangent planes of a logarithmic spiral function. Each piece of the crystal works in the same manner as a single-crystal analyzer. An X-ray beam diffracted from a specimen is diffracted successively by individual crystals of the analyzer, and these diffracted beams are detected separately by a one-dimensional position-sensitive detector. If the analyzer consists of, for example, ten pieces of crystal, ten diffraction patterns can be observed in a single diffractometer scan, and they can be integrated into a single diffraction pattern. Thus the resulting intensity becomes greater by one order of magnitude, while the angular resolution is the same as that of a single-crystal analyzer. The geometrical aspects of the analyzer are described, and some experimental results are given.
Near‐station topographic masses correction for high‐accuracy gravimetric prospecting
Authors: Schiavone D. , Capolongo D. , Loddo M.
Published: April 2009

The expanding role of gravity prospecting in mineral and hydrocarbon exploration as well as seismic and volcanic risk studies will be related to its ability to provide high‐resolution anomalies. To achieve this goal it is necessary to consider the errors resulting from the topographic corrections, in particular near‐station effects. Such errors are relevant not only for severe topographies but also for relatively flat surfaces involving microgravity applications and large‐scale surveys.

Indeed, the errors introduced by low‐resolution digital elevation models can be of the same order of magnitude as the anomalies of interest. This basic fact is demonstrated by tests on synthetic models. The results of this analysis are summarized in an intuitive graph that can be used to estimate what near‐station topographic resolution is necessary for a specific survey. For the Vulcano Island test site (in Southern Italy), we also compare results obtained using three different representations of the topographic surface with different horizontal resolutions and vertical precisions: one from existing photogrammetric data, the second from a digitized map and the third from a very high‐resolution laser scanning system. Among the three methods, laser scanning is shown to obtain the highest resolution topographic reconstructions in the shortest time. Some weaknesses of the laser scanning methodology are discussed and we suggest ways of overcoming them.
Climate warming effects on the Olea europaea–Bactrocera oleae system in Mediterranean islands: Sardinia as an example
Authors: PONTI LUIGI , COSSU Q. ANTONIO , GUTIERREZ ANDREW PAUL
Published: April 2009

Global warming will affect all species but in largely unknown ways, with certain regions such as the Mediterranean Basin and its major islands including Sardinia being particularly vulnerable to desertification. Olive (Olea europaea) is of eco‐social importance in the Mediterranean where it was domesticated. This drought‐resistant crop and its major pest, the olive fly (Bactrocera oleae), have tight biological links that make them a suitable model system for climate change studies in the Mediterranean. Here a physiologically based weather‐driven demographic model of olive and olive fly is used to analyze in detail this plant–pest system in Sardinia under observed weather (10 years of daily data from 48 locations), three climate warming scenarios (increases of 1, 2 and 3 °C in average daily temperature), and a 105‐year climate model scenario for the Alghero location (e.g. 1951–2055). grass gis is used to map model predictions of olive bloom dates and yield, total season‐long olive fly pupae, and percent fruit attacked by the fly. Island wide simulation data are summarized using multivariate regression. Model calibration with field bloom date data were performed to increase simulation accuracy of olive flowering predictions under climate change. As climate warms, the range of olive is predicted to expand to higher altitudes and consolidate elsewhere, especially in coastal areas. The range of olive fly will extend into previously unfavorable cold areas, but will contract in warm inland lowlands where temperatures approach its upper thermal limits. Consequently, many areas of current high risk are predicted to have decreased risk of fly damage with climate warming. Simulation using a 105‐year climate model scenario for Alghero, Sardinia predicts changes in the olive–olive fly system expected to occur if climate continued to warm at the low rate observed during in the past half century.
A study of the impact of information technology on firm performance: a flexible production function approach
Authors: Sircar Sumit , Choi Jung
Published: April 2009

Most previous studies of the impact of information technology (IT) on firm performance have relied on the Cobb–Douglas production function, which makes unrealistic assumptions. These include assuming that (1) the scale elasticity, i.e. returns to scale, is constant throughout the entire output range; (2) the elasticity of substitution between inputs is one, whereas it can be anywhere from zero to infinity in practice; and (3) there are no complex interrelationships between inputs, i.e. no squared or product terms. The translog production function (used in two previous studies) does not make these assumptions and is therefore more accurate. However, the two previous studies found no significant difference between the two. This research has extended previous work on the impact of IT investments by providing more accurate results in some areas and new findings in others. IT's importance is shown to be much greater than previously thought. The translog function is used to demonstrate that the productivity paradox does not hold (i.e. both IT labor and capital indeed have a significant impact on firm revenues), but with considerably different results, i.e. the impact of IT is markedly more significant than that obtained from the Cobb–Douglas. Another interesting finding is that of scale elasticity. Our results show that this is less than 1, implying decreasing returns to scale of output. Finally, the substitutability between inputs was determined, which is not possible with the Cobb–Douglas. It was found that the partial elasticities of substitution for IT labor with IT capital and non‐IT labor were quite substantial.
The research questions and methodological adequacy of clinical studies of the voice and larynx published in Brazilian and international journals
Authors: Vieira Vanessa Pedrosa , De Biase Noemi , Peccin Maria Stella , Atallah Álvaro Nagib
Published: April 2009

Objective  To evaluate the methodological adequacy of voice and laryngeal study designs published in speech‐language pathology and otorhinolaryngology journals indexed for the ISI Web of Knowledge® (ISI® Web) and the MEDLINE® database.

Methods  A cross‐sectional study conducted at the Universidade Federal de São Paulo (Federal University of São Paulo). Two Brazilian speech‐language pathology and otorhinolaryngology journals (Pró‐Fono and Revista Brasileira de Otorrinolaringologia) and two international speech‐language pathology and otorhinolaryngology journals (Journal of Voice, Laryngoscope), all dated between 2000 and 2004, were hand‐searched by specialists. Subsequently, voice and larynx publications were separated, and a speech‐language pathologist and otorhinolaryngologist classified 374 articles from the four journals according to objective and study design.

Results  The predominant objective contained in the articles was that of primary diagnostic evaluation (27%), and the most frequent study design was case series (33.7%). A mere 7.8% of the studies were designed adequately with respect to the stated objectives. There was no statistical difference in the methodological quality of studies indexed for the ISI® Web and the MEDLINE® database.

Conclusion  The studies published in both national journals, indexed for the MEDLINE® database, and international journals, indexed for the ISI® Web, demonstrate weak methodology, with research poorly designed to meet the proposed objectives. There is much scientific work to be done in order to decrease uncertainty in the field analysed.
Sexually dimorphic immune response in the harem polygynous Wellington tree weta Hemideina crassidens
Authors: KELLY CLINT D. , JENNIONS MICHAEL D.
Published: April 2009

Abstract Adult males are often less immunocompetent than females. One explanation for this is that intense sexual selection causes males to trade‐off investment in immunity with traits that increase mating success. This hypothesis is tested in the Wellington tree weta (Hemideina crassidens), a large, sexually dimorphic orthopteran insect in which males possess enormous mandibular weaponry used during fights for access to female mates. Field‐collected males have a significantly greater immune response (greater melanotic encapsulation) than females, suggesting that body condition, longevity or an allied trait is important to male fitness, or that females require materials for egg production that would otherwise be used to boost immunity. Although immunity is expected to trade‐off against reproductive traits in both sexes, there is no significant relationship between immune response and weapon or testes size in males, nor fecundity in females.
Through a Glass, Darkly: The Vision and Visions of Political Theory
Authors: Smith Graham M.
Published: April 2009

This article assesses the recent history and possible future of political theory in Britain. Part One surveys the difficulties that political theory has faced. In particular, it focuses on the relationship between political theory and three developments in the study of politics: (i) the divorce of Anglo-American and continental political theory; (ii) the rise of the idea of a political science; and (iii) the tendency to narrow the focus of Anglo-American political theory around the themes of liberalism and justice. In Part Two the article focuses on the nature of both seeing and being seen by political theory. In doing so a conception of political theory is developed that views it as the activity of seeing ourselves reflected with others. Such an account of political theory advances it as (i) a social activity; that (ii) focuses on the importance of understanding; and (iii) involves a perspectivism based around a reflective seeing with others. This opens a space for a pluralistic political theory—a pluralism that reflects both perspectives and change, but one that is always limited by the reality, values and value of others, and the possibility of a shared understanding.
Implicit Perception and Level of Processing in Object-Substitution Masking
Authors: Chen Zhe , Treisman Anne
Published: April 2009

Object-substitution masking (OSM) refers to reduced target discrimination when the target is surrounded by a sparse mask that does not overlap with the target in space but trails it in time. In four experiments, we used a novel paradigm to investigate the extent of processing of a masked target in OSM. We measured response-compatibility effects between target and mask, both when the offsets were simultaneous and when the offset of the mask was delayed. Evidence for both OSM and a dissociation between perception and awareness was found when detecting the match between the target and the mask required feature but not categorical analyses. Our results suggest that the locus of disruption in OSM is likely to be beyond feature analysis of the unreported target.
A Dynamic Neural Field Model of Visual Working Memory and Change Detection
Authors: Johnson Jeffrey S. , Spencer John P. , Luck Steven J. , Schöner Gregor
Published: April 2009

Efficient visually guided behavior depends on the ability to form, retain, and compare visual representations for objects that may be separated in space and time. This ability relies on a short-term form of memory known as visual working memory. Although a considerable body of research has begun to shed light on the neurocognitive systems subserving this form of memory, few theories have addressed these processes in an integrated, neurally plausible framework. We describe a layered neural architecture that implements encoding and maintenance, and links these processes to a plausible comparison process. In addition, the model makes the novel prediction that change detection will be enhanced when metrically similar features are remembered. Results from experiments probing memory for color and for orientation were consistent with this novel prediction. These findings place strong constraints on models addressing the nature of visual working memory and its underlying mechanisms.
EXPLAINING THE UTILIZATION OF RELATIVE PERFORMANCE EVALUATION IN LOCAL GOVERNMENT: A MULTI‐THEORETICAL STUDY USING DATA FROM SWEDEN
Authors: Johansson Tobias , Siverbo Sven
Published: April 2009

One of the more lasting imprints that New Public Management (NPM) has made in the public sector is an increase in the popularity of performance measurement. In Sweden, performance measurement has gained popularity in the public sector, not least at the local government level with the use of relative performance evaluation (RPE). Because utilization of RPE is a decentralized and optional mode of governance, a somewhat heterogeneous practice has evolved. The aim of this paper is to examine the causes of this differentiated practice. We jointly examine economic, political and institutional/cultural explanations in order to account for the utilization of RPE. The empirical material consists of archival data and a questionnaire sent to all Swedish municipalities in late 2005. We show that RPE adoption and use partly has different antecedents and that the institutional/cultural perspective appears to have greater explanatory power than economic and political, not least as a consequence of the potential to explain decoupling and the importance of change facilitating capabilities. The investigation contributes specifically to the literature on the utilization of RPE in local governments and more generally to the literature on why and to what extent management accounting practices are utilized.
MEASUREMENT AND HEALTH CARE MANAGEMENT
Authors: Aidemark Lars‐Göran , Funck Elin K.
Published: April 2009

Over recent decades many health care organisations have ‘modernised’ their management accounting systems by using the balanced scorecard (BSC). However, public health care involves multi‐dimensional goals and resolving conflicts of interest. The question is whether a management control system based on measurements is suitable in a health care context. Light can be shed on this question using a study of the application of a BSC over a ten‐year period at Högland Hospital. The study shows that the BSC and measurements of output and behaviour became a way of approaching unanswered questions about processes and quality development. Medical professionals with management responsibility, in co‐operation with medical professionals responsible for different specialities, determined measures and targets and the measurements were integrated into activity processes and affected activities.
Effects of species and habitat positional errors on the performance and interpretation of species distribution models
Authors: Osborne Patrick E. , Leitão Pedro J.
Published: April 2009

Aim  A key assumption in species distribution modelling is that both species and environmental data layers contain no positional errors, yet this will rarely be true. This study assesses the effect of introduced positional errors on the performance and interpretation of species distribution models.

Location  Baixo Alentejo region of Portugal.

Methods  Data on steppe bird occurrence were collected using a random stratified sampling design on a 1‐km2 pixel grid. Environmental data were sourced from satellite imagery and digital maps. Error was deliberately introduced into the species data as shifts in a random direction of 0–1, 2–3, 4–5 and 0–5 pixels. Whole habitat layers were shifted by 1 pixel to cause mis‐registration, and the cumulative effect of one to three shifted layers investigated. Distribution models were built for three species using three algorithms with three replicates. Test models were compared with controls without errors.

Results  Positional errors in the species data led to a drop in model performance (larger errors having larger effects – typically up to 10% drop in area under the curve on average), although not enough for models to be rejected. Model interpretation was more severely affected with inconsistencies in the contributing variables. Errors in the habitat layers had similar although lesser effects.

Main conclusions  Models with species positional errors are hard to detect, often statistically good, ecologically plausible and useful for prediction, but interpreting them is dangerous. Mis‐registered habitat layers produce smaller effects probably because shifting entire layers does not break down the correlation structure to the same extent as random shifts in individual species observations. Spatial autocorrelation in the habitat layers may protect against species positional errors to some extent but the relationship is complex and requires further work. The key recommendation must be that positional errors should be minimised through careful field design and data processing.