bluuebunny/crossref_metadata_2025 huggingface dataset:
Deformation of a nanoporous silica under compressive loading
Authors: Han Aijie , Punyamurthula Venkata K. , Lu Weiyi , Qiao Yu
Published: April 2008

In a compression experiment on a nanoporous silica gel, it is observed that at a high pressure the collapse of nanoporous structure provides a mechanism for plastic deformation, leading to an energy absorption efficiency much higher than that of many conventional protection and damping materials. Even though the network material is brittle, the overall behavior of the silica gel is ductile. After the compression test, the nanopore volume is largely reduced while the variation in nanopore surface area is secondary. According to a first-order poromechanic analysis, the effective plastic deformation is dominated by the buckling of the nanopore walls parallel to the external loading.
Experimental techniques for multiphase flows
Authors: Powell Robert L.
Published: April 2008

This review discusses experimental techniques that provide an accurate spatial and temporal measurement of the fields used to describe multiphase systems for a wide range of concentrations, velocities, and chemical constituents. Five methods are discussed: magnetic resonance imaging (MRI), ultrasonic pulsed Doppler velocimetry (UPDV), electrical impedance tomography (EIT), x-ray radiography, and neutron radiography. All of the techniques are capable of measuring the distribution of solids in suspensions. The most versatile technique is MRI, which can be used for spatially resolved measurements of concentration, velocity, chemical constituents, and diffusivity. The ability to measure concentration allows for the study of sedimentation and shear-induced migration. One-dimensional and two-dimensional velocity profiles have been measured with suspensions, emulsions, and a range of other complex liquids. Chemical shift MRI can discriminate between different constituents in an emulsion where diffusivity measurements allow the particle size to be determined. UPDV is an alternative technique for velocity measurement. There are some limitations regarding the ability to map complex flow fields as a result of the attenuation of the ultrasonic wave in concentrated systems that have high viscosities or where multiple scattering effects may be present. When combined with measurements of the pressure drop, both MRI and UPDV can provide local values of viscosity in pipe flow. EIT is a low cost means of measuring concentration profiles and has been used to study shear-induced migration in pipe flow. Both x-ray and neutron radiographes are used to image structures in flowing suspensions, but both require highly specialized facilities.
Numerical study on the shear-induced lift force acting on a spherical bubble in aqueous surfactant solutions
Authors: Fukuta Masato , Takagi Shu , Matsumoto Yoichiro
Published: April 2008

A single bubble motion in aqueous surfactant solutions is discussed in this paper. We focus on the change of the lift force acting on a bubble in a linear shear flow under the condition that the bubble surface is contaminated by surfactant adsorption which leads the Marangoni effect. With an increase of Langmuir number which corresponds to a decrease of desorption rate constant of surfactant, the lift force acting on a spherical bubble decreases from the value of a clean bubble to near zero. This reduction is significantly related to a nonaxisymmetric distribution of pressure on the surface. Comparing the present results with those of our previous simulations using an axisymmetric stagnant cap model, the lift coefficients in the present simulations show larger values than those of the stagnant cap model. This is due to a nonaxisymmetric distribution of surface concentration. This asymmetry of the distribution enhances the asymmetry of the surface pressure distribution, which ends up the larger shear-induced lift force than that of the axisymmetric stagnant cap model.
Shape oscillations on bubbles rising in clean and in tap water
Authors: Veldhuis Christian , Biesheuvel Arie , van Wijngaarden Leen
Published: April 2008

This paper deals with air bubbles rising in purified water in the range of equivalent diameters where surface oscillations appear on the interface. The shape of the bubbles including these capillary distortions is recorded by taking a large number of high speed pictures for each spiraling or zigzagging bubble trajectory. In analogy with surface harmonics, the oscillations are indicated as (2,0) axisymmetric and with wavelength equal to the distance from pole to pole and (2,2) nonaxisymmetric and with wavelength equal to one-half of the length of the equator. In the second series of experiments, the phenomena in the wakes of rising bubbles are made visible by using Schlieren optics, which are applicable because a temperature gradient is applied to the water. The frequencies of vortex shedding correspond to the (2,0) mode of surface oscillation, whereas in other works reported in the literature, they correspond to twice the frequency of the spiraling or zigzagging bubble paths. By measurements and by analysis, it is shown here that the latter is due to contamination of surfactants.
Pairwise interaction of capsules in simple shear flow: Three-dimensional effects
Authors: Lac Etienne , Barthès-Biesel Dominique
Published: April 2008

We use a boundary integral formulation to investigate the collision of two identical capsules in simple shear flow. Each capsule consists of a viscous liquid drop enclosed by an elastic membrane. The hydrodynamic interaction is characterized by an irreversible cross-flow displacement after the capsules have crossed each other, as also observed for rough spheres or drops. This deflection would cause a shear-induced dispersion in a dilute suspension of capsules. After a previous work devoted to the interaction of two capsules located in the same shear plane, here, we focus on the more general case of capsules also shifted in the vorticity direction. For sufficiently spaced trajectories, the capsules exhibit negative deflections which displace them to closer streamlines after they have crossed. Furthermore, the cross-flow displacement occurs mainly in the vorticity direction. Both phenomena are in contradiction with the conclusions drawn for a pair of drops, and are, therefore, attributed to the elastic nature of the capsule interface.
Mixing and evaporation of liquid droplets injected into an air stream flowing at all speeds
Authors: Moukalled F. , Darwish M.
Published: April 2008

This paper deals with the formulation, implementation, and testing of three numerical techniques based on (i) a full multiphase approach, (ii) a multisize-group (MUSIG) approach, and (iii) a heterogeneous MUSIG (H-MUSIG) approach for the prediction of mixing and evaporation of liquid droplets injected into a stream of air. The numerical procedures are formulated following an Eulerian approach, within a pressure-based fully conservative finite volume method equally applicable in the subsonic, transonic, and supersonic regimes, for the discrete and continuous phases. The k-ε two-equation turbulence model is used to account for the droplet and gas turbulence with modifications to account for compressibility at high speeds. The performances of the various methods are compared by solving for two configurations involving streamwise and cross-stream sprayings into subsonic and supersonic streams. Results, which are displayed in the form of droplet velocity vectors, contour plots, and axial profiles, indicate that solutions obtained by the various techniques exhibit a similar behavior. Differences in values are relatively small with the largest being associated with droplet volume fractions and vapor mass fraction in the gas phase. This is attributed to the fact that with MUSIG and H-MUSIG, no droplet diameter equation is solved and the diameter of the various droplet phases is held constant, as opposed to the full multiphase approach.
The effect of soluble surfactant on the transient motion of a buoyancy-driven bubble
Authors: Tasoglu Savas , Demirci Utkan , Muradoglu Metin
Published: April 2008

The effect of soluble surfactants on the unsteady motion and deformation of a bubble rising in an otherwise quiescent liquid contained in an axisymmetric tube is computationally studied by using a finite-difference/front-tracking method. The unsteady incompressible flow equations are solved fully coupled with the evolution equations of bulk and interfacial surfactant concentrations. The surface tension is related to the interfacial surfactant concentration by a nonlinear equation of state. The nearly spherical, ellipsoidal, and dimpled ellipsoidal-cap regimes of bubble motion are examined. It is found that the surfactant generally reduces the terminal velocity of the bubble but this reduction is most pronounced in the nearly spherical regime in which the bubble behaves similar to a solid sphere and its terminal velocity approaches that of an equivalent solid sphere. Effects of the elasticity number and the bulk and interfacial Peclet numbers are examined in the spherical and ellipsoidal regimes. It is found that the surface flow and interfacial surfactant concentration profiles exhibit the formation of a stagnant cap at the trailing end of the bubble in the ellipsoidal regime at low elasticity and high interfacial Peclet numbers. Bubble deformation is first reduced due to rigidifying effect of the surfactant but is then amplified when the elasticity number exceeds a critical value due to overall reduction in the surface tension.
Secondary electron emission from distributed ion scattering off surfaces for space instrumentation
Authors: Devoto P. , Médale J.-L. , Sauvaud J.-A.
Published: April 2008

We present an alternative method for generating start electrons for time of flight (TOF) space plasma analyzers. The technique presented here takes advantage of the processes occurring during the scattering of the particles off a surface, i.e., kinetic electron emission. The use of a thin microchannel plate as a scattering surface allows us to distribute this surface along a single plane normal to the particle velocity. The uncertainty on the TOF distance is thus minimized, allowing a greater mass resolution. The first tests carried out showed that a mass resolution of 10 for a beam energy of 10keV is easily reachable.
Time-dependent photoionization of azulene: Competition between ionization and relaxation in highly excited states
Authors: Blanchet Valérie , Raffael Kevin , Turri Giorgio , Chatel Béatrice , Girard Bertrand , Garcia Ivan Anton , Wilkinson Iain , Whitaker Benjamin J.
Published: April 2008

Pump-probe photoionization has been used to map the relaxation processes taking place from highly vibrationally excited levels of the S2 state of azulene, populated directly or via internal conversion from the S4 state. Photoelectron spectra obtained by 1+2′ two-color time-resolved photoelectron imaging are invariant (apart from in intensity) to the pump-probe time delay and to the pump wavelength. This reveals a photoionization process which is driven by an unstable electronic state (e.g., doubly excited state) lying below the ionization potential. This state is postulated to be populated by a probe transition from S2 and to rapidly relax via an Auger-like process onto highly vibrationally excited Rydberg states. This accounts for the time invariance of the photoelectron spectrum. The intensity of the photoelectron spectrum is proportional to the population in S2. An exponential energy gap law is used to describe the internal conversion rate from S2 to S0. The vibronic coupling strength is found to be larger than 60±5μeV.
Phototermal self-excitation of nanomechanical resonators in liquids
Authors: Ramos D. , Mertens J. , Calleja M. , Tamayo J.
Published: April 2008

We report the use of the photothermal actuation for the self-excitation of a selected vibration mode of a microcantilever in liquid. The gain of the positive feedback loop is adjusted in order to obtain a negative effective damping. In this regime, the amplitude noise is squeezed due to the nonlinear saturation of the system and the phase noise is largely reduced. The microcantilever vibration achieved a frequency stability of the order of 1ppm for a bandwidth of 1Hz. This is at least two orders of magnitude better than previous measurements in liquids. The obtained sensitivity is applied for detecting in real time the change of the fluid properties when glycerol is added to water at a concentration of 1% (m∕m).
Distribution function in quantal cumulant dynamics
Authors: Shigeta Yasuteru
Published: April 2008

We have derived a quantum distribution function in terms of cumulants that are expectation values of a (anti)symmetric-ordered product of position and momentum fluctuation operators. A second-order approximation leads a Gaussian distribution function, which is positive definite and has proper marginals so that the Shannon entropy can be evaluated.
Fiber taper coupling to chalcogenide microsphere modes
Authors: Grillet Christian , Bian Shu Ning , Magi Eric C. , Eggleton Benjamin J.
Published: April 2008

We report the fabrication and optical characterization of microsphere in chalcogenide (As2Se3). We show that high Q modes of a 9.2μm diameter chalcogenide glass can be efficiently excited via evanescent coupling using a silica tapered fiber. Loaded Q factors of more than 20 000 have been measured. Fine analysis of the coupling spectrum around 1619nm led to an estimation of the microsphere eccentricity of less than 1%. Owing to the unique combination properties of chalcogenide glass and the microspheres geometry, we expect this architecture to offer an ideal environment for versatile applications on both the telecommunication and midinfrared wavelength windows.
Vacancy-mediated dopant diffusion activation enthalpies for germanium
Authors: Chroneos A. , Bracht H. , Grimes R. W. , Uberuaga B. P.
Published: April 2008

Electronic structure calculations are used to predict the activation enthalpies of diffusion for a range of impurity atoms (aluminium, gallium, indium, silicon, tin, phosphorus, arsenic, and antimony) in germanium. Consistent with experimental studies, all the impurity atoms considered diffuse via their interaction with vacancies. Overall, the calculated diffusion activation enthalpies are in good agreement with the experimental results, with the exception of indium, where the most recent experimental study suggests a significantly higher activation enthalpy. Here, we predict that indium diffuses with an activation enthalpy of 2.79eV, essentially the same as the value determined by early radiotracer studies.
Effects of crop and pasture rotations and surface cover on rainfall infiltration on a Kandosol in south-west Queensland
Authors: Thomas G. A. , Orange D. N. , King A. J.
Published: April 2008

An experiment was conducted on a Kandosol in south-west Queensland from 2001 to 2005 to determine the effects of fallow management practices and crop and pasture rotations on soil properties and crop production. In April 2004, infiltration measurements were made using a rainfall simulator at the end of a 6-month fallow period following harvest of crop phases (wheat under reduced tillage and zero tillage, chickpea under zero tillage) and following termination of pasture phases (2-year legume and grass + legume leys) with herbicide application and zero tillage during the fallow period. Measurements were made at 3 surface cover levels in each treatment: (i) where crop or pasture dry matter was cut at ground level and removed to approximate 0% cover, (ii) at existing cover percentage, and (iii) where wheat straw was added to give 100% cover. In a separate study to monitor water infiltration, the movement of bromide applied to the soil surface in November 2003 was monitored in the soil profile to 1.5 m soil depth in April 2004 and February 2005.
Mean cumulative infiltration after 100 mm rainfall over 1 h was 35, 42, and 69 mm (l.s.d. P = 0.05, 6) with 0%, existing, and 100% cover, respectively, and was greater following wheat (52 mm) than following chickpea (39 mm) under zero tillage (l.s.d. P = 0.05, 13). Short-term pasture leys did not appear to improve infiltration characteristics of the soil under the conditions of this study.
In the rainfall simulator study, mean drainage of water below 1.5 m soil depth was 8.5% of applied rainfall. In the bromide tracer study, only ~12% of the applied bromide could be accounted for in the 0–1.5 m soil depth 15 months after application. Rainfall received during this period was similar to the long-term mean amount.
Results demonstrate the importance of surface cover in increasing rainfall infiltration on this soil, thereby potentially improving soil water storage for crop and pasture production and reducing the risk of runoff and soil erosion. However, the relatively rapid movement of water and solutes through the soil profile has implications for possible adverse effects of drainage to lower parts of the landscape and for nutrient leaching below the root-zone, decreasing the availability of soil and applied nutrients to crops and pastures.
The crystal structure and dimerization interface of GADD45γ
Authors: Schrag Joseph D. , Jiralerspong Sarn , Banville Myriam , Jaramillo Maria Luz , O'Connor-McCourt Maureen D.
Published: April 2008

Gadd45 proteins are recognized as tumor and autoimmune suppressors whose expression can be induced by genotoxic stresses. These proteins are involved in cell cycle control, growth arrest, and apoptosis through interactions with a wide variety of binding partners. We report here the crystal structure of Gadd45γ, which reveals a fold comprising an αβα sandwich with a central five-stranded mixed β-sheet with α-helices packed on either side. Based on crystallographic symmetry we identified the dimer interface of Gadd45γ dimers by generating point mutants that compromised dimerization while leaving the tertiary structure of the monomer intact. The dimer interface comprises a four-helix bundle involving residues that are the most highly conserved among Gadd45 isoforms. Cell-based assays using these point mutants demonstrate that dimerization is essential for growth inhibition. This structural information provides a new context for evaluation of the plethora of protein–protein interactions that govern the many functions of the Gadd45 family of proteins.
Phenotypic transcription factors epigenetically mediate cell growth control
Authors: Ali Syed A. , Zaidi Sayyed K. , Dacwag Caroline S. , Salma Nunciada , Young Daniel W. , Shakoori Abdul R. , Montecino Martin A. , Lian Jane B. , van Wijnen Andre J. , Imbalzano Anthony N. , Stein Gary S. , Stein Janet L.
Published: April 2008

Ribosomal RNA (rRNA) genes are down-regulated during osteogenesis, myogenesis, and adipogenesis, necessitating a mechanistic understanding of interrelationships between growth control and phenotype commitment. Here, we show that cell fate-determining factors [MyoD, myogenin (Mgn), Runx2, C/EBPβ] occupy rDNA loci and suppress rRNA expression during lineage progression, concomitant with decreased rRNA expression and reciprocal loss of occupancy by c-Myc, a proliferation-specific activator of rRNA transcription. We find interaction of phenotypic factors with the polymerase I activator upstream binding factor UBF-1 at interphase nucleoli, and this interaction is epigenetically retained on mitotic chromosomes at nucleolar organizing regions. Ectopic expression and RNA interference establish that MyoD, Mgn, Runx2, and C/EBPβ each functionally suppress rRNA genes and global protein synthesis. We conclude that epigenetic control of ribosomal biogenesis by lineage-specific differentiation factors is a general developmental mechanism for coordinate control of cell growth and phenotype.
Mobile language choices — The use of English and isiXhosa in text messages (SMS)
Authors: Deumert Ana , Masinyana Sibabalwe Oscar
Published: April 2008

This paper looks at language choice and use in South African SMS communication (texting) among bilingual (isiXhosa / English-speaking) users. Although English is the preferred language for most of the 22 participants (aged between 18 and 27), SMSes also create a forum for isiXhosa literacy (either in isiXhosa messages or in mixed English-isiXhosa messages). The English-language SMSes produced by these bilingual speakers share many of the features which have been reported for English SMS communication internationally (abbreviations, paralinguistic restitutions, non-standard spellings), and provide evidence for what one might call a global English SMS standard. At the same time, however, their SMSes also contain local linguistic features and, in particular, local, cultural content. The isiXhosa messages differ markedly from the writers’ English-language messages in that they contain no abbreviated material, non-standard spellings or paralinguistic restitutions and thus violate the sociolinguistic maxims of SMS / texting as postulated by Thurlow (2003). These bilingual writers thus communicate in the electronic medium using two different languages as well as two, non-overlapping sets of sociolinguistic norms.
Effects of Cigarette Smoke in Mice Wound Healing is Strain Dependent
Authors: Cardoso Juliana F. , Souza Bruna R. , Amadeu Thaís P. , Valença Samuel S. , Porto Luís Cristóvào M. S. , Costa Andréa M. A.
Published: April 2008

It has been clinically and experimentally shown that cigarette smokers suffer from impaired wound healing, but the mechanisms that lead to the alterations are not well understood. The aim of this study was to investigate if the effects of cigarette smoke exposure on excisional cutaneous wound healing are different depending on the strain (Swiss, BALB/c and C57BL/6 mice) studied. Male mice were exposed to smoke of nine whole cigarettes per day, 3 times/day, daily, for 10 days. In the 11th day a full-thickness excisional wound was performed. Control group was sham-exposed and also had a full-thickness excisional wound. The cigarette smoke exposure protocol was performed until euthanasia. Animals were euthanatized 14 days after wounding. Wound contraction was evaluated 7 and 14 days after lesion. Sections were stained with hematoxylin-eosin, Sirius red or toluidine blue and immunostained for alpha-smooth muscle actin. Smoke exposed animals presented delay in wound contraction, in fibroblastic and inflammatory cells recruitment and in myofibroblastic differentiation; those alterations were strain dependent. Cigarette smoke exposure also affected mast cells recruitment and neoepidermis thickness. In conclusion, the present study demonstrated that the effects of cigarette smoke in mice cutaneous wound healing are related to mice strain studied.
Expression of Serine/Threonine Protein-Kinases and Related Factors in Normal Monkey and Human Retinas: The Mechanistic Understanding of a CDK2 Inhibitor Induced Retinal Toxicity
Authors: Saturno Grazia , Pesenti Manuela , Cavazzoli Cristiano , Rossi Anna , Giusti Anna M. , Gierke Berthold , Pawlak Michael , Venturi Miro
Published: April 2008

Protein-kinase inhibitors are among the most advanced compounds in development using the new drug discovery paradigm of developing small-molecule drugs against specific molecular targets in cancer. After treatment with a cyclin dependent kinase CDK2 inhibitor in monkey, histopathological analysis of the eye showed specific cellular damage in the photoreceptor layer. Since this CDK2 inhibitor showed activity also on other CDKs, in order to investigate the mechanism of toxicity of this compound, we isolated cones and rods from the retina of normal monkey and humans by Laser Capture Microdissection. Using Real-Time PCR we first measured the expression of cyclin dependent protein-kinases (CDK)1, 2, 4, 5, Glycogen synthase kinase 3β (GSK3β) and microtubule associated protein TAU. We additionally verified the presence of these proteins in monkey eye sections by immunohistochemistry and immunofluorescence analysis and afterwards quantified GSK3β , phospho-GSK3β and TAU by Reverse Phase Protein Microarrays. With this work we demonstrate how complementary gene expression and protein-based technologies constitute a powerful tool for the understanding of the molecular mechanism of a CDK2 inhibitor induced toxicity. Moreover, this investigative approach is helpful to better understand and characterize the mechanism of species-specific toxicities and further support a rational, molecular mechanism-based safety assessment in humans.
Melanin Precursor 5,6-Dihydroxyindol: Protective Effects and Cytotoxicity on Retinal Cells in vitro and in vivo
Authors: Heiduschka Peter , Blitgen-Heinecke Petra , Tura Aysegül , Kokkinou Despina , Julien Sylvie , Hofmeister Sabine , Bartz-Schmidt Karl Ulrich , Schraermeyer Ulrich
Published: April 2008

5,6-Dihydroxyindole (DHI) is a melanin pigment precursor with antioxidant properties. In the light of a report about cytotoxicity of DHI, the aim of this study was to assess possible toxic effects of DHI on cells related to the eye, such as human ARPE-19 cells and mouse retinal explants. Moreover, DHI was tested on its effects on retinal function in vivo using electroretinography. We found cytotoxicity of DHI against ARPE-19 cells at 100 μM, but not at 10 μM. 10 μM DHI exhibited a slight, though not significant protective activity against UV-A damage in ARPE-19 cells. We found cytoprotection in cultured mouse retinas by 50 μM DHI or its diacetylated derivative 5,6-diacetoxyindole (DAI), respectively. In ERG measurements in vivo, amplitudes were decreased only slightly by 100 μM DHI compared to saline, whereas a better preservation of amplitudes was visible at 10 μM DHI, in particular with respect to cones. In histological sections, more cones were found at 10 μM DHI than at 100 μM DHI. As a conclusion, DHI shows a slight protective effect at 10 μM both in vitro and in vivo. At 100 μM, it shows a strong cytotoxicity in vitro, which is strongly reduced in vivo.
Subtle cues of predation risk: starlings respond to a predator's direction of eye-gaze
Authors: Carter Julia , Lyons Nicholas J , Cole Hannah L , Goldsmith Arthur R
Published: April 2008

For prey animals to negotiate successfully the fundamental trade-off between predation and starvation, a realistic assessment of predation risk is vital. Prey responses to conspicuous indicators of risk (such as looming predators or fleeing conspecifics) are well documented, but there should also be strong selection for the detection of more subtle cues. A predator's head orientation and eye-gaze direction are good candidates for subtle but useful indicators of risk, since many predators orient their head and eyes towards their prey as they attack. We describe the first explicit demonstration of a bird responding to a live predator's eye-gaze direction. We present wild-caught European starlings (
Sturnus vulgaris
) with human ‘predators’ whose frontal appearance and gaze direction are manipulated independently, and show that starlings are sensitive to the predator's orientation, the presence of eyes and the direction of eye-gaze. Starlings respond in a functionally significant manner: when the predator's gaze was averted, starlings resumed feeding earlier, at a higher rate and consumed more food overall. By correctly assessing lower risk and returning to feeding activity earlier (as in this study), the animal gains a competitive advantage over conspecifics that do not respond to the subtle predator cue in this way.
Environment-contingent sexual selection in a colour polymorphic fish
Authors: Gray Suzanne M , Dill Lawrence M , Tantu Fadly Y , Loew Ellis R , Herder Fabian , McKinnon Jeffrey S
Published: April 2008

Sexual selection could be a driving force in the maintenance of intraspecific variation, but supporting observations from nature are limited. Here, we test the hypothesis that spatial heterogeneity of the visual environment can influence sexual selection on colourful male secondary traits such that selective advantage is environment contingent. Using a small fish endemic to Sulawesi, Indonesia (Telmatherina sarasinorum) that has five male colour morphs varying in frequency between two visually distinct mating habitats, we used direct behavioural observations to test the environment-contingent selection hypothesis. These observations were combined with measurements of the visual environment, fish coloration and the sensitivity of visual photopigments to determine whether differential morph conspicuousness was associated with reproductive success across habitats. We found that blue and yellow males are most conspicuous in different habitats, where they also have the highest reproductive fitness. A less conspicuous grey morph also gained high reproductive success in both habitats, raising the possibility that alternative behaviours may also contribute to reproductive success. In a comprehensive analysis, conspicuousness was strongly correlated with reproductive success across morphs and environments. Our results suggest an important role for spatially heterogeneous environments in the maintenance of male colour polymorphism.
Local resource competition and local resource enhancement shape primate birth sex ratios
Authors: Silk Joan B , Brown Gillian R
Published: April 2008

Sex ratio theory provides a powerful source of testable predictions about sex allocation strategies. Although studies of invertebrates generally support predictions derived from the sex ratio theory, evidence for adaptive sex ratio biasing in vertebrates remains contentious. This may be due to the fact that most studies of vertebrates have focused on facultative adjustment in relation to maternal condition, rather than processes that might produce uniform sex biases across individuals. Here, we examine the effects of local resource enhancement (LRE) and local resource competition (LRC) on birth sex ratios (BSRs). We also examine the effects of sex differences in the costs of rearing male and female offspring on BSRs. We present data from 102 primate species and show that BSRs are skewed in favour of the dispersing sex in species that do not breed cooperatively, as predicted by the LRC model. In accordance with the LRE model, BSRs are generally skewed in favour of the more beneficial sex in cooperatively breeding primate species. There is no evidence that BSRs reflect the extent of sexual size dimorphism, an indirect measure of the costs of rearing male and female offspring. These analyses suggest that adaptive processes may play an important role in the evolution of BSRs in vertebrates.
Faces Behind the Figures: Interviews with Children Excluded from Primary School
Authors: Hayden Carol , Ward Derek
Published: April 2008

This article presents a viewpoint on school exclusion from 22 primary‐age children excluded from 20 different schools in two English local education authorities, (a county council and an inner London borough) during the 1993–94 academic year. Some of the methodological and ethical issues about researching children are outlined and considered. The approach and methods used in the research are explained. Interviews with children showed exclusion to be a significant but negative event for them, yet they were optimistic about a return to school. Children showed an awareness of what was considered to be appropriate or inappropriate behaviour in their school. They frequently referred to incidents of physical aggression as the reason for their exclusion. It is concluded that this awareness of appropriate behaviour as well as their optimism must be recognised and harnessed when young children are reintegrated into school following a period of exclusion.
The Contribution of Voluntary Organizations to the Care of Children with Life‐limiting Incurable Disorders and their Families
Authors: Cornish Jocelyn , While Alison , Citrone Christina
Published: April 2008

A national postal survey of voluntay organizations providing for children with life‐limiting incurable disorders (n = 147) is described. The majority of organizations originated from the motivation of parents or care workers in response to deficiencies in service provision from other agencies. A wide variety of services were available from the organizations with over half providing an information service, emotional support and counselling, patient and family support and a telephone helpline. The provision of some services, for example respite care, was, hoverer, associated with the size of annual budgets. Publicity, referral and funding arrangements are also discussed. The role of voluntary organizations as partners in care with statutory agencies is discussed in the light of instability of funding arrangements and the use of health and social work staff as the main source of information about voluntary services to parents. Areas of further research in this field are suggested.
CXCR6 is expressed in human prostate cancer in vivo and is involved in the in vitro invasion of PC3 and LNCap cells
Authors: Hu Weidong , Zhen Xinming , Xiong Bin , Wang Bicheng , Zhang Weibing , Zhou Wenhui
Published: April 2008

In spite of the clinical importance of prostate cancer (PCa) bone metastasis, the precise mechanisms for the directed migration of malignant cells remain unclear. In the present study, the expression of CXCR6 in human PCa and benign prostatic hyperplasia samples, and the expression of CXCL16 in human osseous tissues were determined by immunohistochemistry. It was found that the level of CXCR6 protein expression was elevated in human malignant prostate tumors, and CXCL16 was expressed positively by human osteocytes in vivo. The in vitro experiments further confirmed that the PCa cell lines PC3 and LNCap expressed CXCR6 at both the mRNA and protein levels, and exogenous CXCL16 has the potential to stimulate the invasion of PC3 and LNCap. To further elucidate the role of the CXCL16–CXCR6 axis in PCa progression, we compared the expression of CXCR6 and CXCR4 in human PCa tissues and the effects of CXCL16 and CXCL12 on the in vitro invasion of PC3 and LNCap cells. It was shown that CXCR6 and CXCR4 proteins were coexpressed and elevated in human PCa samples, and CXCL16 and CXCL12 promoted the invasion of PC3 and LNCap via their respective receptors. Furthermore, in contrast to CXCL12, which enhanced the activity of matrix metalloproteinase (MMP) 9 and MMP2 in PC3 and LNCap, CXCL16 ligation resulted in stronger MMP9 and MMP2 activity in LNCap but not in PC3. Our results suggest that besides CXCL12/CXCR4, CXCL16/CXCR6 might be another important factor involved in PCa bone metastasis. (Cancer Sci 2008; 99: 1362–1369)
Regulation of growth factor signaling by FRS2 family docking/scaffold adaptor proteins
Authors: Gotoh Noriko
Published: April 2008

The FRS2 family of adaptor/scaffold proteins has two members, FRS2α and FRS2β. Both proteins contain N‐terminal myristylation sites for localization on the plasma membrane and a PTB domain for binding to limited species of receptor tyrosine kinases (RTKs), including the FGF receptor, the neurotophin receptor, RET, and ALK. Activation of these RTKs allows FRS2 proteins to become phosphorylated of tyrosine residues and then bind to Grb2 and Shp2, a SH2 domain‐containing adaptor and a tyrosine phosphatase, respectively. Subsequently, Shp2 activates a Ras/ERK pathway and Grb2 activates a Ras/ERK, phosphatidyl inositol (PI)‐3 kinase and ubiquitination/degradation pathways by binding to SOS, Gab1, and Cbl via the SH3 domains of Grb2. FRS2α acts as ‘a conning center’ in FGF signaling mainly because it induces sustained levels of activation of ERK via Shp2‐binding sites and Grb2‐binding sites, though the contribution of the former is greater. Indeed, FRS2α knockout mice and mice with mutated Shp2‐binding sites exhibit a variety of phenotypes due to defects in FGF signaling in vivo. Although FRS2β binds to the EGF receptor, it does not induce tyrosine phosphorylation on the receptor. Instead, it inhibits EGF signaling, resulting in inhibition of EGF‐induced cell proliferation and cell transformation. Based on these findings, the involvement of FRS2 proteins in tumorigenesis should be studied extensively to be validated as candidate biomarkers for the effectiveness of treatments targeting RTKs such as the FGF receptor and EGF receptor. (Cancer Sci 2008; 99: 1319–1325)
Phytoplasmas: bacteria that manipulate plants and insects
Authors: HOGENHOUT SASKIA A. , OSHIMA KENRO , AMMAR EL‐DESOUKY , KAKIZAWA SHIGEYUKI , KINGDOM HEATHER N. , NAMBA SHIGETOU
Published: April 2008

Taxonomy:   Superkingdom Prokaryota; Kingdom Monera; Domain Bacteria; Phylum Firmicutes (low‐G+C, Gram‐positive eubacteria); Class Mollicutes; Candidatus (Ca.) genus Phytoplasma.

Host range:   Ca. Phytoplasma comprises approximately 30 distinct clades based on 16S rRNA gene sequence analyses of ~200 phytoplasmas. Phytoplasmas are mostly dependent on insect transmission for their spread and survival. The phytoplasma life cycle involves replication in insects and plants. They infect the insect but are phloem‐limited in plants. Members of Ca. Phytoplasma asteris (16SrI group phytoplasmas) are found in 80 monocot and dicot plant species in most parts of the world. Experimentally, they can be transmitted by approximately 30, frequently polyphagous insect species, to 200 diverse plant species.

Disease symptoms:   In plants, phytoplasmas induce symptoms that suggest interference with plant development. Typical symptoms include: witches’ broom (clustering of branches) of developing tissues; phyllody (retrograde metamorphosis of the floral organs to the condition of leaves); virescence (green coloration of non‐green flower parts); bolting (growth of elongated stalks); formation of bunchy fibrous secondary roots; reddening of leaves and stems; generalized yellowing, decline and stunting of plants; and phloem necrosis. Phytoplasmas can be pathogenic to some insect hosts, but generally do not negatively affect the fitness of their major insect vector(s). In fact, phytoplasmas can increase fecundity and survival of insect vectors, and may influence flight behaviour and plant host preference of their insect hosts.

Disease control:   The most common practices are the spraying of various insecticides to control insect vectors, and removal of symptomatic plants. Phytoplasma‐resistant cultivars are not available for the vast majority of affected crops.
Effects of host‐plant shift on immune and other key life‐history traits of an eruptive Geometrid, Epirrita autumnata (Borkhausen)
Authors: YANG SHIYONG , RUUHOLA TEIJA , HAVIOLA SANNA , RANTALA MARKUS J.
Published: April 2008

Abstract 1. Population density of Epirrita autumnata (Lepidoptera: Geometridae) reaches outbreak densities regularly in northernmost Scandinavia. During these outbreak years, the most abundant host species, the mountain birch (Betula pubescens ssp. czerepanovii), is regularly exhausted, although larvae may rescue themselves from starvation by using alternative host species.

2. In this paper, the effects of the shift of host species on the immune defence and other life‐history traits of E. autumnata were investigated, and possible consequences for population dynamics were briefly discussed. Moth larvae were reared on the leaves of the main host, mountain birch, until larvae reached their third instar. After this, larvae were allocated randomly to five treatments: larvae were either allowed to finish larval stage on the mountain birch or were shifted onto four alternative host species that are typical species for the area.

3. As expected, the host species had a major effect on fitness traits: body weight, development, and survival rate of the moths. The pupal weight was lower and development rates slower on the three alternative host species, Salix myrsinifolia Salisb., Vaccinium uliginosum L., and Betula nana L., than on the main host, mountain birch.

4. The immunity was, however, the same or better on the alternative hosts than on the main host. The immunity and pupal weights were negatively related, suggesting a trade‐off between body size and immunocompetence.

5. The decreased body size and fecundity of E. autumnata during outbreak years may be partly due to the shift to alternative host species whereas the host‐plant species probably does not affect markedly the rate of parasitism.
Increased expression of osteopontin in patients with triple‐negative breast cancer
Authors: Wang X. , Chao L. , Ma G. , Chen L. , Tian B. , Zang Y. , Sun J.
Published: April 2008

Background  Patients with triple‐negative [oestrogen receptor (ER) negative, progesterone receptor (PR) negative, and human epidermal growth factor receptor 2 (HER‐2/neu) negative] breast cancer, accounting for about 15% of breast cancer cases, are associated with aggressive histology, poor prognosis and shorter survival. Osteopontin is a chemokine‐like phosphorylated glycoprotein that plays important role in cancer progression and is found to be a metastasis‐associated protein in breast cancer. The goal of the study was to evaluate osteopontin protein expression levels in triple‐negative breast carcinomas to determine if they correlated with clinicopathological parameters, thus providing additional support for osteopontin functioning and better understanding of triple‐negative breast cancer.

Materials and methods   A database of 239 patients, in whom all three markers (ER, PR, and HER‐2/neu) were available, was reviewed. We performed osteopontin protein expression analyses by means of immunohistochemistry on 117 breast carcinoma tissue samples, and then assessed the mean value of osteopontin expression against triple‐negative status and clinicopathological parameters.

Results  Of the 239 patients in the study, 47 were classified as triple negative. Of the 117 osteopontin‐test patients in this cohort, mean osteopontin levels were significantly higher in the triple‐negative breast cancers than in non‐triple‐negative subtype (P = 0·035). TNM (tumours, nodes, metastases) stage were significantly associated with osteopontin levels (P = 0·038). Univariate analysis showed tumour cell osteopontin positivity above an optimized cut‐point to be significantly associated with decreased disease‐free survival, but not overall survival. In the multivariate model, osteopontin was an independent prognostic factor for disease‐free survival.

Conclusions  Patients with osteopontin overexpression develop predominantly triple‐negative tumours. Osteopontin overexpression is associated with tumour aggressiveness and poor prognosis.
Evaluation of the factors affecting direct polarization solid state 31P‐NMR spectroscopy of bulk soils
Authors: Conte P. , ŠMejkalová D. , Piccolo A. , Spaccini R.
Published: April 2008

31P‐NMR spectroscopy on bulk soils is a powerful tool for the identification of the different phosphorus forms in soils and for the evaluation of the dynamics of soil P. Up to now the majority of the papers dealt with liquid state 31P‐NMR spectroscopy on soluble soil organic substances. Only few papers were addressed to the study of the different phosphorus forms directly in bulk soils. In the present paper, some organic and inorganic phosphates of known structures, which are likely to be present in soil systems, were studied by direct polarization (DP) magic angle spinning (MAS) 31P‐NMR spectroscopy in order to understand the electronic factors responsible for chemical shifts of the phosphorus (P) nucleus and to serve as guidelines to assign P resonances in soil spectra. Number of hydrating water molecules, type of counter‐cation, degree of covalence, and spatial conformation of P in phosphate structures were found to affect signal positions in 31P‐NMR spectra. Both hydrating water and increase in degree of covalence of the X‐O‐P bonds (X=H, Na) enhanced the electronic density (ED) around P, thereby producing up‐field shifts in 31P‐NMR spectra. The exchange of the Na+ counter‐cation with NH4+ resulted in an increase of the cation potential (PC) that is a measure of the cation polarizing power, and induced a down‐field shift of P signals, due to a corresponding reduction in ED around the P nucleus. Both NMR down‐ and up‐field shifts were observed in organic phosphates, and were dependent on the spatial orientation of the phosphate groups that may have been fixed anisotropically in the solid state. Based on the factors that influence P chemical shifts for standard phosphates, attempts to assign 31P‐NMR signals in the spectra of five different unperturbed bulk soils were made.
Tocopherol metabolism, oxidation and recycling under high light stress in Arabidopsis
Authors: Kobayashi Naoko , DellaPenna Dean
Published: April 2008

Tocopherols are synthesized and accumulated by all plants and many cyanobacteria. The quenching and scavenging of reactive oxygen species and lipid peroxy radicals by tocopherols can result in the formation of various tocopherol oxidation compounds. A targeted GC/MS profiling method was developed to quantify all tocopherols and pathway intermediates, and 23 potential α‐ and γ‐tocopherol oxidation products. This method was used to study the response of wild‐type Arabidopsis (Col) and the tocopherol biosynthetic mutants vte1, vte2 and vte4 during 12 h low‐ and high‐light treatments (LL and HL, 90 and 1500 μmol photon m−2 sec−1, respectively) and a subsequent 12 h dark recovery period. All tocopherols and pathway intermediates exhibited HL‐dependent increases except 2,3‐dimethyl‐6‐phytyl‐1,4‐benzoquinone (DMPBQ) in vte1 and β‐tocopherol in Col. Profiling of potential tocopherol oxidation products during HL treatment indicated the presence of only α‐tocopherolquinol (α‐TQH2) in Col and only γ‐tocopherolquinol (γ‐TQH2) in vte4, both of which accumulated to similar levels and with similar kinetics the two genotypes. However, during dark recovery, the level of α‐TQH2 in Col decreased several times faster than that of γ‐TQH2 in vte4, suggesting the presence of biochemical processes with higher specificity for α‐TQH2. 14C‐labeled α‐tocopherolquinone (α‐TQ) applied to isolated Col chloroplasts was converted to 14C‐α‐tocopherol, demonstrating the existence of a plastid‐based system for recycling oxidized α‐tocopherol. The accumulation of 14C‐trimethylphytylbenzoquinone (TMPBQ) by isolated vte1 plastids treated with 14C‐labeled α‐TQ is consistent with the tocopherolquinone‐recycling pathway utilizing a yet to be identified plastid‐localized dehydratase that converts tocopherolquinone to TMPBQ.