bluuebunny/crossref_metadata_2025 huggingface dataset:
Generating intense ultrashort radiation by reflecting an ultrashort laser pulse from a thin target
Authors: Zhang Wenmin , Yu M. Y.
Published: October 2011

Particle-in-cell simulation and analytical modeling demonstrate that the reflection of a single-cycle light pulse from a thin target can produce an ultrashort ultraintense electromagnetic field.
Structure of the InAlAs/InP interface by atomically resolved energy dispersive spectroscopy
Authors: Klenov Dmitri O. , Zide Joshua M. O.
Published: October 2011

The structure of epitaxially grown InAlAs/InP interfaces was studied using atomically resolved x-ray energy dispersive spectroscopy in scanning transmission electron microscopy. As and P sublattices show sharp termination on the interface. The In sublattice is continuous across the interface. The study has shown the depletion of the Al concentration at the interface; at the last atomic columns of the InAlAs, In occupancy is close to 100%, while Al occupancy is almost zero. A monolayer of InAs at the interface is consistent with substitution of As for P at the surface preceding growth.
Communication: Drift velocity of Brownian particle in a periodically tapered tube induced by a time-periodic force with zero mean: Dependence on the force period
Authors: Zitserman V. Yu. , Berezhkovskii A. M. , Antipov A. E. , Makhnovskii Yu. A.
Published: October 2011

We study the drift of a Brownian particle in a periodically tapered tube, induced by a longitudinal time-periodic force of amplitude |F| that alternates in sign every half-period. The focus is on the velocity dependence on the force period, which is usually considered not tractable analytically. For large |F| we derive an analytical solution that gives the velocity as a function of the amplitude and the period of the force as well as the geometric parameters of the tube. The solution shows how the velocity decreases from its maximum value to zero as the force period decreases from infinity (adiabatic regime) to zero. Our analytical results are in excellent agreement with those obtained from 3D Brownian dynamics simulations.
Different magnetic properties of rhombohedral and cubic Ni2+ doped indium oxide nanomaterials
Authors: Sun Qingbo , Zeng Yuping , Zuo Kaihui
Published: October 2011

Transition metal ions doped indium oxide nanomaterials were potentially used as a kind of diluted magnetic semiconductors in transparent spintronic devices. In this paper, the influences of Ni2+ doped contents and rhombohedral or cubic crystalline structures of indium oxide on magnetic properties were investigated. We found that the magnetic properties of Ni2+ doped indium oxide could be transferred from room temperature ferromagnetisms to paramagnetic properties with increments of doped contents. Moreover, the different crystalline structures of indium oxide also greatly affected the room temperature ferromagnetisms due to different lattice constants and almost had no effects on their paramagnetic properties. In addition, both the ferromagnetic and paramagnetic properties were demonstrated to be intrinsic and not caused by impurities.
Theoretical study of adsorption of lithium atom on carbon nanotube
Authors: Senami Masato , Ikeda Yuji , Fukushima Akinori , Tachibana Akitomo
Published: October 2011

We investigate the adsorption of lithium atoms on the surface of the (12,0) single wall carbon nanotube (SWCNT) by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsive force between lithium atoms destabilizes a system for the large number of lithium atoms.
Chip off the old block: Meteorites are definitively linked to stony asteroids
Authors: Levi Barbara Goss
Published: October 2011

The parental identification was clinched by analyses of a sample of dust brought from an asteroid to Earth by a Japanese space mission.
An Outcome-Based Resource Allocation Model for Local Education Services in Wales
Authors: Bramley Glen , Watkins David , Karley Noah Kofi
Published: October 2011

Funding for local services such as education has for long been allocated on formulae claiming to reflect local variations in needs, although in practice these have often tended to reflect the patterns of past expenditure. The idea that such formulae might reflect explicit outcome criteria is not new, but only with the recent development of integrated multilevel databases has it become possible to develop this approach in a serious way. We identify the essential requirements of an outcome approach and discuss variant criteria in such a system. Data for the whole compulsory-age-range state school system in Wales are analysed to generate models predicting key attainment levels for individual pupils at 11 and 16. These are complemented by models for school costs and the incidence of special educational needs. Using these models it is possible to estimate the cost of achieving various target degrees of improvement or equalisation of outcomes, or compensation for relevant social disadvantages, balanced against constraints on the maximum degree of redistribution (via minimum school budgets). The results indicate that it is certainly possible to envisage such a system in operation, albeit subject to gradualist implementation, although the redistribution could have implications for particular localities which were controversial.
Corporate Political Strategizing in the European Union during the 2007–10 Recession: An Exploratory Study
Authors: Barron Andrew , Hultén Peter
Published: October 2011

Using original data collected from a survey of Brussels-based Government Affairs Managers (GAMs) in May and June 2010, we explore the political actions of firms in the European Union during the 2007–10 financial crisis. Findings suggest that the financial constraints imposed by the crisis had a significant impact on whether GAMs entered into short-term or long-term relationships with policy makers and whether they engaged in individual or collective action. Significant crosscountry differences were also observed between the political objectives pursued by firms, their propensity to engage in collective political action, and the tactics they use to influence policy makers. Taken together, these findings challenge institutional explanations of EU lobbying, which suggest that the EU system of policy making provides powerful incentives for firms to adopt specific lobbying behaviours in order to gain a seat at the EU policy-making table.
The Continuing Popularity of the Neighbourhood and Neighbourhood Governance in the Transition from the ‘Big State’ to the ‘Big Society’ Paradigm
Authors: Bailey Nick , Pill Madeleine
Published: October 2011

The neighbourhood in both the UK and Europe continues to dominate thinking about the quality of life in local communities, representation and empowerment, and how local services can be delivered most effectively. For several decades a series of centrally funded programmes in neighbourhood governance have targeted localities suffering deprivation and social exclusion in England. From these much can be learnt about the strengths and limitations of a local approach to achieving multiple objectives. We review the findings of a case study of neighbourhood governance in the City of Westminster and draw on evaluations of two national programmes. In the conclusions we discuss the problems arising from multiple objectives and examine the prospects for neighbourhood governance as the national paradigm moves away from ‘big state’ solutions towards the less-well-defined ‘big society’ approach and the reinvention of ‘localism’. While the rationale for neighbourhood governance may change, the ‘neighbourhood’ as a site for service delivery and planning remains as important now as in the past.
Morpho-structural and physiological performance of Sangiovese and Montepulciano cvv. (Vitis vinifera) under non-limiting water supply conditions
Authors: Palliotti Alberto , Poni Stefano , Silvestroni Oriana , Tombesi Sergio , Bernizzoni Fabio
Published: October 2011

Morpho-structural and physiological traits of Sangiovese and Montepulciano varieties (Vitis vinifera L. – two red grapes widely cultivated in Italy), grown outside under non-limiting water supply conditions were evaluated in 2007 and 2008 and results were correlated with yield components and grape composition. The 2-year analysis showed intraspecific differences in canopy characteristics, leaf and shoot properties, photosynthetic ability, water use efficiency, vine yield and grape composition. Compared with Sangiovese, Montepulciano was able to assure a higher whole-canopy seasonal net CO2 exchange rate during the season (+38% in mid morning and +49% in mid afternoon). It also had higher water use efficiency (especially early in the morning and in late afternoon) and a higher vine yield (+16%). Furthermore, total soluble solids (+1.7 °Brix), anthocyanins (+0.44 mg cm–2 berry skin) and phenolic compounds (+0.88 mg cm–2 berry skin) were higher in the grapes. To ensure this performance, Montepulciano vines have to support higher costs of growth and maintenance processes, made possible because of the increased respiration activity of the canopy during the night. We confirmed that vine yield and grape composition is strictly dependent on the seasonal photosynthetic capacity of the canopy. Therefore, Montepulciano should be put in a position to fully realise this substantial photosynthetic potential, by avoiding or reducing environmental stress. Sangiovese is structurally and morpho-physiologically better able to withstand any stress during the summer than Montepulciano. Sangiovese xylem tissue had larger mean vessel density and smaller mean vessel diameter and hydraulic conductance than Montepulciano, holding the hypothesis of less susceptibility to conduit damage.
Chromium supplementation: a tool for alleviation of thermal stress in poultry.
Authors: Șahİn K. , Tuzcu M. , Smith M. O. , Sahİn N.
Published: October 2011

Thermal stress is one of the major causes leading to loss of production and profit in the poultry industry. Productivity in general and feed efficiency, nutrient utilization, growth rate, egg production and egg quality, in particular, are depressed as a result of thermal stress. Thermal temperature also adversely affects availability of minerals (e.g. zinc (Zn), chromium (Cr) and selenium (Se)), suggesting that increased mineral excretion and decreased mineral retention are also other important consequences of thermal stress. Moreover, thermal stress leads to oxidative stress, inflammation and reduced antioxidant status of the bird
in vivo
, resulting in oxidative damage and decreased plasma concentrations of minerals (e.g. Zn and Cr) and vitamins (e.g. vitamin C and vitamin E). Chromium is a well-known essential trace element for animals. It appears to have a beneficial role in the regulation of insulin's action on carbohydrate, protein and lipid metabolism. Chromium is a part of glucose tolerance factor and chromodulin. In addition, Cr is thought to be essential for activating certain enzymes and for stabilization of proteins and nucleic acids. Chromium is postulated to function as an antioxidant. Some factors such as stress, high carbohydrate intake, obesity and acute exercise cause Cr depletion. Chromium deficiency causes disruption in carbohydrate and protein metabolism, reduction in insulin sensitivity in peripheral tissues, as well as impairment in growth rate. Chromium is used in the diets of thermal-stressed poultry because of its reported benefits. Chromium supplementation may decrease levels of blood corticosterone, glucose, inflammation and oxidative stress markers and increase weight gain in thermal-stressed poultry. Dietary intake of Cr may also improve the metabolizability of organic nutrients, retention of trace elements and meat quality in thermal-stressed poultry. This review deals with the effects of dietary Cr supplementation in poultry reared under thermal stress.
Food miles - the economic, environmental and social significance of the focus on local food.
Authors: Oglethorpe D.
Published: October 2011

Local food has received much attention in recent years not only through academic study but also through media-driven initiatives to promote more sustainable food systems. Whether these initiatives are correct in assuming that local food will drive more sustainable consumption and production, however, is moot. This review examines the literature relating to local food and reveals some mixed messages. In particular, in relation to our pre-conceived notions about local food providing a more 'wholesome' means of supply, messages relating to food miles and production simplicity may be misleading. The food miles issue, when taken literally in terms of transport efficiency, appears perverse as does environmental impacts connected with simpler processing and packaging of local food. However, there are counterbalancing economic and social welfare gains that may be attributable to local food that are less emblematic but just as relevant.
A review of research on forest-related environmental markets (including certification schemes, bioenergy, carbon markets and other ecosystem services).
Authors: Dargusch P. , Maraseni T. N. , Schmidt P.
Published: October 2011

This review analyses the major themes extant across 199 research articles published in various peer-reviewed forestry and economics journals between January 2002 and June 2009 on the topic of forest-related environmental markets. The reviewed articles are categorized according to four areas of research: forest stewardship and sustainable supply chain certification; renewable energy generation from woody biomass; forest-based greenhouse gas emissions offsets and carbon markets; and ecosystem services from forests. Two key research questions are identified for future research: (1) how can certification schemes be used to promote ecologically and socially sustainable bioenergy generation from forest-related feed stocks and (2) how can certification schemes be used to promote ecologically and socially sustainable afforestation-based greenhouse gas emissions offsets that offer broader social and ecosystem benefits on appropriate regional scales?
Developments in probiotic encapsulation.
Authors: Favaro-Trindade C. S. , Heinemann R. J. B. , Pedroso D. L.
Published: October 2011

Probiotics are live micro-organisms that bring benefits to consumer health. However, to exert these benefits, the micro-organisms must remain viable during processing and for the shelf-life of food (with a recommended number of viable cells above 10
6
UFC/g) and must be resistant to gastrointestinal (GI) fluids. However, in general, probiotic cultures have problems related to their viability, stability and depreciation of the sensory acceptability of foods through the production of off-flavours. Overcoming these problems required considerable research effort. As a result, numerous studies have shown that microencapsulation is an alternative for probiotics to provide stability, viability, no proliferation in food and, additionally, controlled release in the intestine. There are still many challenges in this area, such as determining the mechanisms of release of the content of the microcapsules, development of low-cost enteric polymer microcapsules, development of symbiotic microcapsules and conferring thermal stability to probiotic cultures. In this context, this review aims at demonstrating the advances available in microencapsulation of probiotics.
Ambiguities of Forest Management Decentralization in Ghana
Authors: Teye Joseph K.
Published: October 2011

This article examines the outcomes of forest management decentralization in Ghana. It has been demonstrated that despite claims that Ghana has adopted forest management decentralization policy, actual forest management powers and rights over forest resources are still retained by the central government. The government is only interested in using the decentralization policy to reduce expenditure and extend its control over forest resources. Nevertheless, it has employed policy ambiguities to hide its true intentions from international donors. In order to contain international donor demands for equity in the distribution of natural resource revenue, a small stream of forest revenue is paid to a few unelected traditional rulers and district assembly officials, who are actually within the executive's patronage networks. In the absence of any meaningful reward system and secure rights over forest resources, community forestry committees are not functioning properly.
Howard Chang: Gene regulation in time and space
Authors: Short Ben
Published: October 2011

Chang studies how large groups of genes work together to carry out biological processes.
FAK is required for the assembly of podosome rosettes
Authors: Pan Yi-Ru , Chen Chien-Lin , Chen Hong-Chen
Published: October 2011

Podosomes are dynamic actin-enriched membrane structures that play an important role in invasive cell motility and extracellular matrix degradation. They are often found to assemble into large rosettelike structures in highly invasive cells. However, the mechanism of this assembly remains obscure. In this study, we identified focal adhesion kinase (FAK) as a key molecule necessary for assembly. Moreover, phosphorylation of p130Cas and suppression of Rho signaling by FAK were found to be important for FAK to induce the assembly of podosome rosettes. Finally, we found that suppression of vimentin intermediate filaments by FAK facilitates the assembly of podosome rosettes. Collectively, our results strongly suggest a link between FAK, podosome rosettes, and tumor invasion and unveil a negative role for Rho signaling and vimentin filaments in podosome rosette assembly.
Molecular networks linked by Moesin drive remodeling of the cell cortex during mitosis
Authors: Roubinet Chantal , Decelle Barbara , Chicanne Gaëtan , Dorn Jonas F. , Payrastre Bernard , Payre François , Carreno Sébastien
Published: October 2011

The cortical mechanisms that drive the series of mitotic cell shape transformations remain elusive. In this paper, we identify two novel networks that collectively control the dynamic reorganization of the mitotic cortex. We demonstrate that Moesin, an actin/membrane linker, integrates these two networks to synergize the cortical forces that drive mitotic cell shape transformations. We find that the Pp1-87B phosphatase restricts high Moesin activity to early mitosis and down-regulates Moesin at the polar cortex, after anaphase onset. Overactivation of Moesin at the polar cortex impairs cell elongation and thus cytokinesis, whereas a transient recruitment of Moesin is required to retract polar blebs that allow cortical relaxation and dissipation of intracellular pressure. This fine balance of Moesin activity is further adjusted by Skittles and Pten, two enzymes that locally produce phosphoinositol 4,5-bisphosphate and thereby, regulate Moesin cortical association. These complementary pathways provide a spatiotemporal framework to explain how the cell cortex is remodeled throughout cell division.
Magnetotransport properties of iron microwires fabricated by focused electron beam induced autocatalytic growth
Authors: Porrati F , Sachser R , Walz M-M , Vollnhals F , Steinrück H-P , Marbach H , Huth M
Published: October 2011

We have prepared iron microwires in a combination of focused electron beam induced deposition and autocatalytic growth from the iron pentacarbonyl, Fe(CO)5, precursor gas under ultra-high vacuum conditions. The electrical transport properties of the microwires were investigated and it was found that the temperature dependence of the longitudinal resistivity (ρ
xx
) shows a typical metallic behaviour with a room temperature value of about 88 µΩ cm. In order to investigate the magnetotransport properties we have measured the isothermal Hall-resistivities in the range between 4.2 and 260 K. From these measurements, positive values for the ordinary and the anomalous Hall coefficients were derived. The relation between anomalous Hall resistivity (ρAN) and longitudinal resistivity is quadratic,
, revealing an intrinsic origin of the anomalous Hall effect. Finally, at low temperature in the transversal geometry a negative magnetoresistance of about 0.2% was measured.
Average particle magnetization as an experimental scaling parameter for the yield stress of dilute magnetorheological fluids
Authors: Vereda F , de Vicente J , Segovia-Gutiérrez J P , Hidalgo-Alvarez R
Published: October 2011

We propose an experimental parameter for the scaling of the yield stress (τy) of magnetorheological (MR) fluids: the average particle magnetization ⟨M
p⟩ as estimated from magnetization curves of the MR suspensions. When τy was expressed as a function of this scaling parameter, the curves for MR suspensions prepared with particles of different saturation magnetization and even different morphology collapsed together. In addition, the collapse worked reasonably well for a wide range of magnetic fields: from weak fields below which the sensitivity of our magnetorheometer could not detect the τy, to fields close to particle saturation. The collapse failed for particles of highly anisotropic morphology, which must be indicative of non-magnetostatic contributions to the yield stress.
Second harmonic generation from hemicyanine self-assembled monolayer on near-hemispherical gold nanoparticles
Authors: Tanaka Daisuke , Yamaguchi Tatsuya , Gupta Gaurav , Okawa Haruki , Hashimoto Kazuhiko , Kajikawa Kotaro
Published: October 2011

Second-harmonic generation (SHG) was observed from hemicyanine-terminated alkanethiolate self-assembled monolayers (SAMs) formed on near-hemispherical gold nanoparticles (GNPs) prepared by annealing a vacuum-evaporated thin gold film deposited on a quartz glass substrate. The hemicyanine SAMs were formed on the near-hemispherical GNP by immersion of the substrate in an ethanol solution of hemicyanine-terminated alkanedisulfide. Polarized SHG measurements with the support of theoretical calculations revealed that the near-hemispherical GNP surfaces are fully covered with the hemicyanine SAMs. This result is in contrast to our previous study that showed that the hemicyanine SAM does not form fully over the spherical GNPs immobilized on a quartz glass substrate.
High-temperature stability of molybdenum (Mo) back contacts for CIGS solar cells: a route towards more robust back contacts
Authors: Yoon Ju-Heon , Yoon Kwan-Hee , Kim Won Mok , Park Jong-Keuk , Baik Young-Joon , Seong Tae-Yeon , Jeong Jeung-hyun
Published: October 2011

The thermal stability of Mo thin films is indispensable to Cu(In,Ga)Se2 (CIGS) solar cells: CIGS films are deposited above 500 °C. The thermal stabilities of Mo thin films with dense to porous Mo microstructures, which are varied by controlling the sputtering pressure, are investigated. Interface failures are found to occur in buckling mode in denser Mo films, whereas cracking arises in less dense films. The failure modes are apparently dependent on the sign of the residual stress: the former is due to compressive stress, whereas the latter is due to tensile stress. Interestingly, the softening of soda-lime glass at high temperatures reconfigures the film stresses to be more compressive after annealing, which in turn triggers buckling even in films that are tensile-stressed in the as-deposited states. We conclude that the appropriate processing conditions for thermally stable back contacts cannot be obtained with the simple single layer approach. On the basis of this relationship between microstructure, residual stress and the failure modes, it is shown that improvements in film adhesion can widen the processing window for the preparation of robust back contacts, i.e. with a conventional bilayer approach and substrate roughening. Since the bilayer approach employed more compliant porous structures in the bottom layer, back contacts that are better suited to higher stress and temperature can be produced. Furthermore, substrate roughening might make the back contact more conductive as well as more stable because adhesion can be enhanced without the use of an electrically resistive buffer layer.
Factors to Improve Detection of Alfalfa mosaic virus in Soybean
Authors: He B. , Hill J. H. , Hajimorad M. R.
Published: October 2011

Infection of plants with Alfalfa mosaic virus is known to be associated with symptom and virus concentration remission, a phenomenon known as “recovery.” However, for the routine detection of AMV in the infected plants, this phenomena is problematic. Indeed in soybean, detection of AMV has been problematic and inconsistent results have been obtained from tissues collected at different growth stage of the infected plants. In order to determine optimum sampling procedure for analysis by ELISA, three soybean cultivars and five biologically distinct strains of AMV were utilized in this study. Each cultivar was rub-inoculated with each of the strains and all the trifoliolate leaf samples of the infected plants were analyzed by ELISA at 30, 60, and 90 days postinoculation. Results suggested that for all virus strains and cultivars tested, tissue samples should consist of pooled fully developed trifoliolate leaflets that are positioned at the upper parts of the plants. Additionally, symptoms of AMV infection were dependent upon soybean cultivar and virus strain and varied from symptomatic to asymptomatic. This makes it problematic to conclude a soybean plant is AMV infected based upon symptomatology alone.

Accepted for publication 22 July 2011. Published 26 September 2011.
Virtual surgeries in patients with congenital heart disease: a multi-scale modelling test case
Authors: Baretta A. , Corsini C. , Yang W. , Vignon-Clementel I. E. , Marsden A. L. , Feinstein J. A. , Hsia T.-Y. , Dubini G. , Migliavacca F. , Pennati G. ,   The Modeling of Congenital Hearts Alliance (MOCHA) Investigators
Published: October 2011

The objective of this work is to perform a virtual planning of surgical repairs in patients with congenital heart diseases—to test the predictive capability of a closed-loop multi-scale model. As a first step, we reproduced the pre-operative state of a specific patient with a univentricular circulation and a bidirectional cavopulmonary anastomosis (BCPA), starting from the patient's clinical data. Namely, by adopting a closed-loop multi-scale approach, the boundary conditions at the inlet and outlet sections of the three-dimensional model were automatically calculated by a lumped parameter network. Successively, we simulated three alternative surgical designs of the total cavopulmonary connection (TCPC). In particular, a T-junction of the venae cavae to the pulmonary arteries (T-TCPC), a design with an offset between the venae cavae (O-TCPC) and a Y-graft design (Y-TCPC) were compared. A multi-scale closed-loop model consisting of a lumped parameter network representing the whole circulation and a patient-specific three-dimensional finite volume model of the BCPA with detailed pulmonary anatomy was built. The three TCPC alternatives were investigated in terms of energetics and haemodynamics. Effects of exercise were also investigated. Results showed that the pre-operative caval flows should not be used as boundary conditions in post-operative simulations owing to changes in the flow waveforms post-operatively. The multi-scale approach is a possible solution to overcome this incongruence. Power losses of the Y-TCPC were lower than all other TCPC models both at rest and under exercise conditions and it distributed the inferior vena cava flow evenly to both lungs. Further work is needed to correlate results from these simulations with clinical outcomes.
Influence of high-frequency cyclical stimulation on the bone fracture-healing process: mathematical and experimental models
Authors: Gómez-Benito María José , González-Torres Libardo Andrés , Reina-Romo Esther , Grasa Jorge , Seral Belén , García-Aznar José Manuel
Published: October 2011

Mechanical stimulation affects the evolution of healthy and fractured bone. However, the effect of applying cyclical mechanical stimuli on bone healing has not yet been fully clarified. The aim of the present study was to determine the influence of a high-frequency and low-magnitude cyclical displacement of the fractured fragments on the bone-healing process. This subject is studied experimentally and computationally for a sheep long bone. On the one hand, the mathematical computational study indicates that mechanical stimulation at high frequencies can stimulate and accelerate the process of chondrogenesis and endochondral ossification and consequently the bony union of the fracture. This is probably achieved by the interstitial fluid flow, which can move nutrients and waste from one place to another in the callus. This movement of fluid modifies the mechanical stimulus on the cells attached to the extracellular matrix. On the other hand, the experimental study was carried out using two sheep groups. In the first group, static fixators were implanted, while, in the second one, identical devices were used, but with an additional vibrator. This vibrator allowed a cyclic displacement with low magnitude and high frequency (LMHF) to be applied to the fractured zone every day; the frequency of stimulation was chosen from mechano-biological model predictions. Analysing the results obtained for the control and stimulated groups, we observed improvements in the bone-healing process in the stimulated group. Therefore, in this study, we show the potential of computer mechano-biological models to guide and define better mechanical conditions for experiments in order to improve bone fracture healing. In fact, both experimental and computational studies indicated improvements in the healing process in the LMHF mechanically stimulated fractures. In both studies, these improvements could be associated with the promotion of endochondral ossification and an increase in the rate of cell proliferation and tissue synthesis.
Transport in the placenta: homogenizing haemodynamics in a disordered medium
Authors: Chernyavsky Igor L. , Leach Lopa , Dryden Ian L. , Jensen Oliver E.
Published: October 2011

The placenta is an essential component of the life-support system for the developing foetus, enabling nutrients and waste to be exchanged between the foetal and maternal circulations. Maternal blood flows between the densely packed branches of villous trees, within which are foetal vessels. Here, we explore some of the challenges in modelling maternal haemodynamic transport using homogenization approaches. We first show how two measures can be used to estimate the minimum distance over which the distribution of villous branches appears statistically homogeneous. We then analyse a simplified model problem (solute transport by a unidirectional flow past a distribution of point sinks) to assess the accuracy of homogenization approximations as a function of governing parameters (Péclet and Damköhler numbers) and the statistical properties of the sink distribution. The difference between the leading-order homogenization approximation and the exact solute distribution is characterized by large spatial gradients at the scale of individual villi and substantial fluctuations that can be correlated over lengthscales comparable to the whole domain. This study highlights the importance of quantifying errors owing to spatial disorder in multi-scale approximations of physiological systems.
A tentative taxonomy for predictive models in relation to their falsifiability
Authors: Viceconti Marco
Published: October 2011

The growing importance of predictive models in biomedical research raises some concerns on the correct methodological approach to the falsification of such models, as they are developed in interdisciplinary research contexts between physics, biology and medicine. In each of these research sectors, there are established methods to develop cause–effect explanations for observed phenomena, which can be used to predict: epidemiological models, biochemical models, biophysical models, Bayesian models, neural networks, etc. Each research sector has accepted processes to verify how correct these models are (falsification). But interdisciplinary research imposes a broader perspective, which encompasses all possible models in a general methodological framework of falsification. The present paper proposes a general definition of ‘scientific model’ that makes it possible to categorize predictive models into broad categories. For each of these categories, generic falsification strategies are proposed, except for the so-called ‘abductive’ models. For this category, which includes artificial neural networks, Bayesian models and integrative models, the definition of a generic falsification strategy requires further investigation by researchers and philosophers of science.
Is there a ‘plenhaptic’ function?
Authors: Hayward Vincent
Published: October 2011

One approach to gauge the complexity of the computational problem underlying haptic perception is to determine the number of dimensions needed to describe it. In vision, the number of dimensions can be estimated to be seven. This observation raises the question of what is the number of dimensions needed to describe touch. Only with certain simplified representations of mechanical interactions can this number be estimated, because it is in general infinite. Organisms must be sensitive to considerably reduced subsets of all possible measurements. These reductions are discussed by considering the sensing apparatuses of some animals and the underlying mechanisms of two haptic illusions.
Flow sensing by pinniped whiskers
Authors: Miersch L. , Hanke W. , Wieskotten S. , Hanke F. D. , Oeffner J. , Leder A. , Brede M. , Witte M. , Dehnhardt G.
Published: October 2011

Beside their haptic function, vibrissae of harbour seals (Phocidae) and California sea lions (Otariidae) both represent highly sensitive hydrodynamic receptor systems, although their vibrissal hair shafts differ considerably in structure. To quantify the sensory performance of both hair types, isolated single whiskers were used to measure vortex shedding frequencies produced in the wake of a cylinder immersed in a rotational flow tank. These measurements revealed that both whisker types were able to detect the vortex shedding frequency but differed considerably with respect to the signal-to-noise ratio (SNR). While the signal detected by sea lion whiskers was substantially corrupted by noise, harbour seal whiskers showed a higher SNR with largely reduced noise. However, further analysis revealed that in sea lion whiskers, each noise signal contained a dominant frequency suggested to function as a characteristic carrier signal. While in harbour seal whiskers the unique surface structure explains its high sensitivity, this more or less steady fundamental frequency might represent the mechanism underlying hydrodynamic reception in the fast swimming sea lion by being modulated in response to hydrodynamic stimuli impinging on the hair.
Biomimetic vibrissal sensing for robots
Authors: Pearson Martin J. , Mitchinson Ben , Sullivan J. Charles , Pipe Anthony G. , Prescott Tony J.
Published: October 2011

Active vibrissal touch can be used to replace or to supplement sensory systems such as computer vision and, therefore, improve the sensory capacity of mobile robots. This paper describes how arrays of whisker-like touch sensors have been incorporated onto mobile robot platforms taking inspiration from biology for their morphology and control. There were two motivations for this work: first, to build a physical platform on which to model, and therefore test, recent neuroethological hypotheses about vibrissal touch; second, to exploit the control strategies and morphology observed in the biological analogue to maximize the quality and quantity of tactile sensory information derived from the artificial whisker array. We describe the design of a new whiskered robot,
Shrewbot
, endowed with a biomimetic array of individually controlled whiskers and a neuroethologically inspired whisking pattern generation mechanism. We then present results showing how the morphology of the whisker array shapes the sensory surface surrounding the robot's head, and demonstrate the impact of active touch control on the sensory information that can be acquired by the robot. We show that adopting bio-inspired, low latency motor control of the rhythmic motion of the whiskers in response to contact-induced stimuli usefully constrains the sensory range, while also maximizing the number of whisker contacts. The robot experiments also demonstrate that the sensory consequences of active touch control can be usefully investigated in biomimetic robots.
Two-Photon Imaging of Neural Networks in a Mouse Model of Alzheimer’s Disease
Authors: Eichhoff Gerhard , Garaschuk Olga
Published: October 2011

In humans, Alzheimer’s disease (AD) develops over many years. It comprises a chain of subtle yet irreversible alterations in brain function, finally leading to impairment of memory and cognition. Presymptomatic and thus invisible in humans, these alterations can be studied in the animal models of AD. Mouse models of the disease expressing AD-related proteins with familial mutations reproduce several pathological hallmarks of AD. Although the models do not recapitulate the abundant neuronal loss seen in humans, they offer a unique opportunity to learn more about synaptic and cellular mechanisms underlying the disease (both in their essence and in their temporal sequence) through in vivo analyses of brain function. This, however, requires in vivo monitoring of brain function in aged living animals at both a single-cell and network level. Tools developed over the last several decades can be used to selectively mark and to visualize in vivo many important elements of the diseased brain parenchyma, such as amyloid plaques, individual neurons, and glial and microglial cells. Here we describe a method in which cell-type-specific labeling of neurons and glia is combined with in vivo two-photon calcium imaging and fluorescent labeling of amyloid plaques to study functional properties of cortical circuits in a mouse model of AD.
An Assay for Visual Learning in Individual Drosophila Larvae: Figure 1.
Authors: van Swinderen Bruno
Published: October 2011

Vision is a major sensory modality in Drosophila behavior, with more than one-half of the Drosophila brain devoted to visual processing. The mechanisms of vision in Drosophila can now be studied in individuals and in populations of flies by using various paradigms. Simple strategies for conducting visual perception and learning studies consist of individual studies performed on single flies on solid supports (larvae on agar or adults in a T-maze) using a light/dark association paradigm. These approaches are quite easy to implement but are fairly limited in their ability to address questions of visual perception. Nevertheless, the simpler approaches treating vision in one dimension (light, dark) do provide effective paradigms for genetic analysis. This article describes a protocol for larval visual learning. Larvae are transferred back and forth between well-lit or dark agarose plates that either do or do not contain fructose (which is appetitive) as the unconditioned stimulus (US). Such appetitive larval visual memory is tested by tallying the time spent in light or dark quadrants of a plate (without a US).
High-Resolution Multiphoton Imaging of Tumors In Vivo
Authors: Wyckoff Jeffrey , Gligorijevic Bojana , Entenberg David , Segall Jeffrey , Condeelis John
Published: October 2011

Analysis of the individual steps in metastasis is crucial if insights at the molecular level are to be linked to the cell biology of cancer. A technical hurdle to achieving the analysis of the individual steps of metastasis is the fact that, at the gross level, tumors are heterogeneous in both animal models and patients. Human primary tumors show extensive variation in all properties ranging from growth and morphology of the tumor through tumor-cell density in the blood and formation and growth of metastases. Methods capable of the direct visualization and analysis of tumor-cell behavior at single-cell resolution in vivo have become crucial in advancing the understanding of mechanisms of metastasis, the definition of microenvironment, and the markers related to both. This article discusses the use of high-resolution multiphoton imaging of tumors (specifically breast tumors in mice) in vivo.
First Steps for Fluorescence Correlation Spectroscopy of Living Cells: Figure 1.
Authors: Kinjo Masataka , Sakata Hiroshi , Mikuni Shintaro
Published: October 2011

Fluorescence correlation spectroscopy (FCS) has become a powerful and sensitive tool in biochemistry and biophysics. It directly obtains physical parameters such as the average number of fluorescent molecules and their diffusion time in a tiny detection area. It also provides other useful information such as the brightness of molecules. Ultimately, it can give precise information about molecular interactions in the aqueous condition. This article outlines the basic parameters and properties of FCS.
Calculation of scattering patterns from phase-shifting objects using the Radon transform
Authors: Treimer W. , Feye-Treimer U.
Published: October 2011

In the case of neutron (and X-ray) scattering by objects that are about 105times larger than the wavelength, the objects can be considered as (inhomogeneous) phase-shifting media. In contrast with small-angle scattering, the scattering patterns from phase-shifting objects are calculated by the superposition of coherent partial waves that penetrate the object. In order to determine the scattering patterns from large complicated objects, it is proposed to use the two-dimensional Radon transform of the objects and Fraunhofer diffraction. This approach is much easier than using the small-angle scattering treatment, as is shown in this paper.
Potential thermal expansion of calcitic and dolomitic marbles from Andalusia (Spain)
Authors: Luque A. , Leiss B. , Álvarez-Lloret P. , Cultrone G. , Siegesmund S. , Sebastian E. , Cardell C.
Published: October 2011

Marble has historically been used as an ornamental stone because of its aesthetic appeal, ease of polishing and ex;cellent physical properties. One of the main factors affecting the durability of marbles is their thermal behaviour. Although marble is used extensively in Spain as a building and decorative material, little research has been done into its thermal behaviour. In this work, the textural and microstructural properties of seven calcitic and dolomitic marbles from Andalusia (southern Spain) were characterized to assess how these properties affect their thermal response. Rock fabric properties (grain morphology, boundaries and micro-crack populations) were studied by polarized microscopy and lattice preferred orientation using X-ray texture goniometry. Elastic properties were measured by ultrasound, thermal properties were determined by a six-rod dilatometer (thermal expansion) and the opening of micro-cracks was observed using environmental scanning electron microscopy. For each marble, thermal coefficients of calcite and dolomite crystals were calculated using thermo-X-ray diffraction, a novel application to characterize historic marbles. The results show that marble thermal expansion coefficients are related to preferred crystallographic orientation, which can help to identify the directions along which decay occurs. The results also show for the first time that the thermal expansion coefficient of the main components of marble,i.e.calcite and dolomite, is specific to each marble, and plays a key role in their different thermal behaviours. Thermal properties also depend on mineral composition, the existence of micro-cracks and hydric properties.
A sample holder for in-house X-ray powder diffraction studies of protein powders
Authors: Frankær Christian Grundahl , Harris Pernille , Ståhl Kenny
Published: October 2011

A sample holder for handling samples of protein for in-house X-ray powder diffraction (XRPD) analysis has been made and tested on lysozyme. The use of an integrated pinhole reduced the background, and good signal-to-noise ratios were obtained from only 7 µl of sample, corresponding to approximately 2–3 mg of dry protein. The sample holder is further adaptable to X-ray absorption spectroscopy (XAS) measurements. Both XRPD and XAS at the ZnK-edge were tested with hexameric Zn insulin.
Guidelines for chemical peeling in Japan (3rd edition)
Authors:   Committee for Guidelines of Care for Chemical Peeling
Published: October 2011

Chemical peeling may be defined as the therapies, procedures and techniques used for the treatment of certain cutaneous diseases or conditions, and for aesthetic improvement. The procedures include the application of one or more chemical agents to the skin. Chemical peeling has been very popular in both medical and aesthetic fields. Because neither its scientific background is well understood nor a systematic approach established, medical and social problems have taken place. This prompted us to establish and distribute a standard guideline of care for chemical peeling. Previous guidelines such as the 2001 and 2004 versions included minimum standards of care such as indications, chemicals, applications, and any associated precautions, including post‐peeling care. The principles in this updated version of chemical peeling are as follows: (i) chemical peeling should be performed under the strict technical control and responsibility of a physician; (ii) the physician should have sufficient knowledge of the structure and physiology of the skin and subcutaneous tissues, and understand the mechanisms of wound‐healing induced by chemical peeling; (iii) the physician should be board‐certified in an appropriate specialty such as dermatology; and (iv) the ultimate judgment regarding the appropriateness of any specific chemical peeling procedure must be made by the physician while considering all standard therapeutic protocols, which should be presented to each individual patient. Keeping these concepts in mind, this new version of the guidelines includes a more scientific and detailed approach from the viewpoint of evidence‐based medicine.
Population regulation in sexual and asexual rotifers: an eco‐evolutionary feedback to population size?
Authors: Stelzer Claus‐Peter
Published: October 2011

1. Population size is often regulated by density dependence, that is negative feedbacks between growth and population density. Several density‐dependent mechanisms may operate simultaneously in a population.

2. In this study, I focus on two different mechanisms of density‐dependent population regulation, resource exploitation (RE) and density‐dependent sexual reproduction (DDS).

3. I analyse both mechanisms in clonal populations of the rotifer Brachionus calyciflorus, which differ in the investment in sex because of a polymorphism at a single Mendelian locus. Some clones were cyclical parthenogens (CP) and possessed both mechanisms of population regulation (RE + DDS), while other clones were obligate parthenogens (OP) and thus lacking the DDS mechanism.

4. Equilibrium population size was considerably lower in CP clones, compared with OP clones, regardless of the exact measurement variable for population size (numbers of individuals or total biovolume/biomass). Interestingly, the decrease in population size was most pronounced in CP clones that heavily invested in sexual reproduction.

5. This suggests that the DDS mechanism can significantly contribute to population regulation and that genotypes lacking this mechanism (because of a mutation in genes affecting this trait) reach substantially higher population sizes. Apparently, the DDS mechanism operates already at much lower population densities than the RE, causing CP populations to stop growing before they are limited by resources.

6. As these differences in population regulation were caused by genetic variation within a single species and as rapid selective sweeps by OP clones are common in B. calyciflorus, this study provides an example for an eco‐evolutionary feedback on an important ecological variable – equilibrium population size.