bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman Spectroscopy, Fullerenes and Nanotechnology
Authors: Amer Maher S ,   Royal Society of Chemistry
Published: April 2010

This unique book is the first treatment of nanotechnology as the science controlled by the behaviour of thermodynamic small systems. It provides comprehensive discussions on fullerenes as building blocks, Raman spectroscopy as a powerful diagnostic tool, and nanotechnology as the technology bridging the gap between human-made and biological materials systems. Aimed at graduate students, scientists, researchers, and educators interested in academia, government and industry, the text is divided into four chapters. The first covers the potential of nanotechnology to develop a better, deeper understanding of the physical and chemical phenomena observed in natural systems. It also contains a section introducing nanotechnology to the public in simple, non-scientific terms. The second chapter is devoted to Raman spectroscopy and could in itself serve as a basis for a short course on its applications in materials science. The third section covers fullerenes and presents their history and development as well as discussing the structure and production of zero-dimensional, one-dimensional, and two-dimensional fullerenes. The fourth and final chapter serves as a correlation discussion and over view. It emphasizes the unique nano-phenomena exhibited by the fullerene systems as carbon based nanostructured systems. This chapter, and therefore the book, concludes with a discussion on the potential of nano-science and technology to shape the future of human society.
Physicochemical, structural, and mechanical properties of Si3N4 films annealed in O2
Authors: Aguzzoli C. , Marin C. , Figueroa C. A. , Soares G. V. , Baumvol I. J. R.
Published: April 2010

The physicochemical, structural, and mechanical properties of silicon nitride films deposited by radio frequency reactive magnetron sputtering were investigated before and after thermal annealing in O182. As-deposited films were essentially amorphous, stoichiometric, and free from contaminants for a wide range of deposition parameters, with hardness figures ranging from 16.5–22 GPa, depending mainly on the deposition temperature. After O182 annealing at 1000 °C, films hardness converged to 21 GPa, independently of the deposition temperature, which is explained based on the crystallization of the films at this annealing temperature. Moreover, oxygen is incorporated only in 7.5 nm of the Si3N4, forming silicon oxynitride at the top surface of the film, indicating a good oxidation resistance at high temperature. Finally, the elastic strain to failure (H3/E2), which mimics the wear resistance of the film, doubles after the 1000 °C annealing. These observations show the great potential of silicon nitride as a hard coating for high temperature applications.
Atomic resolution in tunneling induced light emission from GaAs(110)
Authors: Reinhardt Maria , Schull Guillaume , Ebert Philipp , Berndt Richard
Published: April 2010

A cryogenic scanning tunneling microscope is used to induce band edge luminescence from GaAs(110). The emission intensity varies within the unit mesh of the surface. This atomic resolution reflects variations of the efficiency of hole injection into states at the valence band maximum. Moreover, the hole injection efficiency is modulated by local potential fluctuations due to dopants.
An ultrahigh vacuum compatible sample holder for studying complex metal surfaces
Authors: Dhaka R. S. , Shukla A. K. , Maniraj M. , D’Souza S. W. , Nayak J. , Barman S. R.
Published: April 2010

We present a design of a compact and versatile sample holder meant for studying complex (ternary) metallic crystals that require sputtering and annealing to high temperatures under ultrahigh vacuum (10−10 mbar range) for obtaining the clean, ordered and stoichiometric surface. A resistive heater is fixed to the sample holder and not to the sample plate, and thus can be thoroughly degassed initially to high temperatures without heating the sample. The heater, which is mounted vertically on the sample holder frame, slides into the sample plate of rectangular cross-section during sample transfer. For efficient cooling that is required for adlayer deposition, Cu braids can be pressed on the sample plate from both sides through a screw mechanism. The sample holder has 5 degrees of freedom including a tilt rotation. The sample holder has been used to study different metal surfaces such as ferromagnetic shape memory alloys, alkali metal and Mn adlayers on Al–Pd–Mn quasicrystal, aluminum metal, and Al–Mn alloys. Here, our recent results on temperature dependent low energy electron diffraction study of Ni2MnGa(100) are presented.
The resolution of the identity approximation for calculations of spin-spin contribution to zero-field splitting parameters
Authors: Ganyushin Dmitry , Gilka Natalie , Taylor Peter R. , Marian Christel M. , Neese Frank
Published: April 2010

In this work, the resolution of the identity (RI) approximation is developed for the calculation of the electron-electron spin-spin coupling (SSC) interaction that is a central component of the zero-field splitting (ZFS) term in the effective spin Hamiltonian. The approximated integrals are then used in large-scale multireference configuration interaction treatments of the SSC interaction. The SSC contribution to the ZFS is treated using the Breit–Pauli spin-spin Hamiltonian in conjunction with first-order perturbation theory. Test calculations on a set of diatomic molecules reveal that the error of the RI approximation does not exceed 0.01 cm−1 even if standard auxiliary basis sets are used. This error of less than 1% is considered to be negligible compared to the presently achievable accuracy of the SSC calculations relative to experimental data. The present development allows the correlated ab initio calculation of ZFS parameters of larger systems such as linear polyenes and linear polyacenes. The basis set convergence of the calculated ZFS values was investigated, and the effect of electronic correlation on the calculated ZFS parameters is discussed.
Space-charge electric field in photorefractive multiple quantum wells
Authors: Zhang Xiangxue , Samiullah Mohammad , Yu Ping
Published: April 2010

We have developed a graphical method to determine the space-charge electric field in photorefractive multiple quantum wells when the photocurrent is dominated by the drift current. The minima and maxima of the space-charge electric field due to space modulated light intensity are obtained from photocurrent measurements under uniform illumination. In addition, we find that the space-charge field depends nonlinearly on the applied electric field and the intensity of light, and changes sharply with the intensity up to a critical intensity beyond which it remains unchanged.
Scalings for radiation from plasma bubbles
Authors: Thomas A. G. R.
Published: April 2010

In this paper, electron trajectories are studied analytically in the rest frame of a plasma bubble using nonevolving, linear, radial electric and azimuthal magnetic fields in a spherical structure. The electron motion is broken into two distinct periods; one where it orbits around the periphery to the rear of the bubble, and one where it performs oscillations within the bubble interior. By using the first period as an initial condition for the second, general scalings are developed for the x-ray radiation produced by the electron oscillations. The equations are also analyzed to give self-trapping conditions for the electron and to examine the sensitivity of the transverse momentum to small variations from an orbit that is a circular arc. The scalings are in reasonable agreement with recent experiments on x-ray generation and predict a peak spectral brightness of S≈6×1027 photons/s mrad mm 0.1%BW of radiation with a critical energy of 300 MeV using a single stage accelerator driven by a 120 PW laser.
Synthesis and growth mechanism of long ultrafine gold nanowires with uniform diameter
Authors: Kura Hiroaki , Ogawa Tomoyuki
Published: April 2010

Homogeneous Au nanowires with 1.5 nm diameters and lengths of over 100 μm were synthesized in an oleylamine matrix via the simple reduction of aurichloride in a limited reaction temperature range around 85 °C. Oleylamine has multifunctional roles as solvent, surfactant, and reductant, and the surfactant induce anisotropic growth by adsorbing on the specific Au crystalline surface. As a result, Au nanowires were grown along the ⟨111⟩ direction of fcc-Au having many hcp atomic stacks. In this synthesis method, various shapes of Au nanostructures were produced simultaneously and this was strongly dependent on the reaction temperature. Au nanowires were provided by reconstruction from nanoparticles or their agglomeration. The growth mechanism of the Au nanowire in this synthesis was found to be quite unique and different from that for a conventional one-dimensional nanostructure which is obtained by anisotropical growth with supplying atoms from external resources.
Analytic gradients for Mukherjee’s multireference coupled-cluster method using two-configurational self-consistent-field orbitals
Authors: Jagau Thomas-C. , Prochnow Eric , Evangelista Francesco A. , Gauss Jürgen
Published: April 2010

Analytic gradients for the state-specific multireference coupled-cluster method suggested by Mahapatra et al. [Mol. Phys. 94, 157 (1998)] (Mk-MRCC) are reported within the singles and doubles approximation using two-configurational self-consistent field (TCSCF) orbitals. The present implementation extends our previous work on Mk-MRCC gradients [E. Prochnow et al., J. Chem. Phys. 131, 064109 (2009)] which is based on restricted Hartree–Fock orbitals and consequently the main focus of the present paper is on the treatment of orbital relaxation at the TCSCF level using coupled-perturbed TCSCF theory. Geometry optimizations on m-arynes and nitrenes are presented to illustrate the influence of the orbitals on the computed equilibrium structures. The results are compared to those obtained at the single-reference coupled-cluster singles and doubles and at the Mk-MRCC singles and doubles level of theory when using restricted Hartree–Fock orbitals.
Advances in high-harmonic fast wave physics in the National Spherical Torus Experiment
Authors: Taylor G. , Bell R. E. , Hosea J. C. , LeBlanc B. P. , Phillips C. K. , Podesta M. , Valeo E. J. , Wilson J. R. , Ahn J-W. , Chen G. , Green D. L. , Jaeger E. F. , Maingi R. , Ryan P. M. , Wilgen J. B. , Heidbrink W. W. , Liu D. , Bonoli P. T. , Brecht T. , Choi M. , Harvey R. W.
Published: April 2010

Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile was measured in NBI-fuelled plasmas when HHFW heating was applied.
Pulsed dc- and sine-wave-excited cold atmospheric plasma plumes: A comparative analysis
Authors: Xiong Q. , Lu X. P. , Ostrikov K. , Xian Y. , Zou C. , Xiong Z. , Pan Y.
Published: April 2010

Cold atmospheric-pressure plasma plumes are generated in the ambient air by a single-electrode plasma jet device powered by pulsed dc and ac sine-wave excitation sources. Comprehensive comparisons of the plasma characteristics, including electrical properties, optical emission spectra, gas temperatures, plasma dynamics, and bacterial inactivation ability of the two plasmas are carried out. It is shown that the dc pulse excited plasma features a much larger discharge current and stronger optical emission than the sine-wave excited plasma. The gas temperature in the former discharge remains very close to the room temperature across the entire plume length; the sine-wave driven discharge also shows a uniform temperature profile, which is 20–30 degrees higher than the room temperature. The dc pulse excited plasma also shows a better performance in the inactivation of gram-positive staphylococcus aureus bacteria. These results suggest that the pulsed dc electric field is more effective for the generation of nonequilibrium atmospheric pressure plasma plumes for advanced plasma health care applications.
On the use of a multiple beam optical sensor for in situ curvature monitoring in liquids
Authors: Van Overmeere Q. , Vanhumbeeck J.-F. , Proost J.
Published: April 2010

Several methods have been developed since the early 1900 to extract thin film stresses from the curvature of the substrate to which it is attached. One robust method particularly suitable for in situ curvature monitoring is the multiple beam optical sensor, which consists in measuring the change in relative spacings between parallel laser beams reflecting off the curved substrate. Although the technique is already well established for curvature monitoring in low pressure, gaseous environments, its use in liquid media has not yet received similar attention. Moreover, in the majority of the published work so far, spot spacings have been assumed to depend linearly on curvature. In this paper, it is first shown that this assumption may induce significant errors, particularly at large curvature. A more accurate set of equations is proposed. Next, the relationship between spot spacings and curvature is established when the substrate of interest is in a liquid, and a constitutive formula is proposed in that case as well. Finally, some practical aspects of the multiple beam technique for performing curvature measurements in a liquid are discussed. Various factors disturbing the measurement resolution are identified, with a specific interest for thin film anodizing, and a cell design is proposed to minimize their effect.
Structural and antireflective characteristics of catalyst-free GaN nanostructures on GaN/sapphire template for solar cell applications
Authors: Park C. Y. , Lim J. M. , Yu J. S. , Lee Y. T.
Published: April 2010

We report the structural and antireflective characteristics of catalyst-free GaN nanostructures on GaN/sapphire template for solar cell applications. The formation of GaN nanostructure depends on the growth temperature. At 530 °C, the nucleation of the initial seed due to the enhanced strain leads to the hexagonal closely packed nanorods. As the growth temperature decreases, the depression of atomic Ga transport changes the films into nanocolumns, and then the nanorods. The catalyst-free GaN nanorods have wurtzite structure and good single crystalline quality. The GaN nanorods exhibit a remarkably low reflectance over a wide-angle broadband spectrum, enhancing the antireflective property of GaN surface.
Oxygen-atmosphere heat treatment in spin-on doping process for improving the performance of crystalline silicon solar cells
Authors: Liu Zhengxin , Takato Hidetaka , Togashi Chiho , Sakata Isao
Published: April 2010

Spin-on doping of phosphorus has been investigated and applied for the emitter fabrication of crystalline Si solar cells. Heat treatment in oxygen atmosphere at relatively low temperature of 550 °C prior to phosphorus diffusion is proved effective for improving solar cell performance, showing a conversion efficiency enhancement of more than 0.2% absolute. Internal quantum efficiency measurements show obvious enhancements at both short and long-wavelength regions. Secondary ion mass spectroscopy and Infrared absorption analysis reveal reduced C impurities after the heat treatment, possibly caused by burning the organic residues in the coated dopant source layer.
Dynamic smoothing of nanocomposite films
Authors: Pei Y. T. , Turkin A. A. , Chen C. Q. , Shaha K. P. , Vainshtein D. , De Hosson J. Th. M.
Published: April 2010

In contrast to the commonly observed dynamic roughening in film growth we have observed dynamic smoothing in the growth of diamondlike-carbon nanocomposite (TiC/a-C) films up to 1.5 μm thickness. Analytical and numerical simulations, based on the Edwards–Wilkinson model and the Mullins model, visualize the effect of the diffusivity parameters and the noise strength on the interface evolution of dynamic smoothing. The prediction is in a good agreement with the measured roughness evolution. High-resolution transmission electron microscopy shows that the formation of an amorphous front layer 2 nm thick excludes possible influence of nanocrystallites on the dynamic growth behavior of the nanocomposite film.
Production of carbonaceous nanostructures from a silver-carbon ambient spark
Authors: Byeon Jeong Hoon , Kim Jang-Woo
Published: April 2010

Using silver-carbon ambient sparks, hollow carbon nanospheres or multiwall carbon nanotubes were produced separately from carbon encapsulated silver nanoparticles (−1,400 K s−1) during relatively slow (−800 K s−1) or fast (−2,900 K s−1) cooling process. Different cooling processes (i.e., different exposures within high temperature) caused the formation of different carbon precipitates in the process of silver mediated graphitization: for −2,900 K s−1 and <−1,400 K s−1, respectively, obtained tubelike and sphere (encapsulated and hollow)-like carbonaceous nanostructures.
Effect of antisite defects on band structure and thermoelectric performance of ZrNiSn half-Heusler alloys
Authors: Qiu Pengfei , Yang Jiong , Huang Xiangyang , Chen Xihong , Chen Lidong
Published: April 2010

Band structures for ZrNiSn with Zr/Sn antisite defects are calculated with ab initio methods. Antisite defects shrink the band gap and enhance the density of states slope near the Fermi level, which are favorable to electrical transport properties for intrinsic semiconductors. The degree of Zr/Sn antisite defects are controlled by annealing time experimentally, and measurements show low electrical resistivity and high Seebeck coefficient for unannealed ZrNiSn, which benefits from the modified electronic structure caused by antisite defects. The maximum ZT is 0.64 at 800 K for unannealed ZrNiSn, which is the highest value for ZrNiSn systems without exterior doping.
Competitive Global City Regions and ‘Sustainable Development’: An Interpretive Institutionalist Account in the South East of England
Authors: Krueger Rob , Gibbs David
Published: April 2010

This paper presents an argument and empirical case study to draw out additional nuance in the social construction of institutions. Adapting the conceptual work of political scientists Mark Bevir and Roderick Rhodes to recent accounts in economic geography of institutional change we present an ‘interpretative analysis’ of recent policy changes in the regulation of land use in competitive global regions in London and the South East, UK. The paper examines the appeal to tradition, the construction of policy dilemmas, and the affect these have on what we think of as neoliberal policy reform.
Gentrification in the Context of ‘Risk Society’
Authors: Skaburskis Andrejs
Published: April 2010

This paper looks at factors explaining gentrification using the neoclassical economic framework. The risk inherent in a move to a lower class neighbourhood is seen as a component of the rent gap that helps preserve working-class neighbourhoods until a tipping point is reached. The factors that affect risk perception and encourage gentrification are placed the context of Ulrich Beck's risk society. The ‘reflexivity’ attribute, the ‘end of fate’—the ‘writing of one's own biography’—bridges the changes in preferences, life style, family formation, and work that contribute to the rise of gentrification.
How to Make Progress in Theories of Spatial Clustering: A Case Study of Malmberg and Maskell's Emerging Theory
Authors: Oinas Päivi , Marchionni Caterina
Published: April 2010

Many social science disciplines suffer from a tradition of tolerating vaguely formulated theoretical claims. The authors report a case study of the explanatory claims made in an emerging knowledge-based theory of clusters proposed by the economic geographers Malmberg and Maskell. In doing so they reinterpret and reconstruct Malmberg and Maskells's theory by applying what is called the ‘contrastive approach’ to explanation from contemporary philosophy of science literature. This approach is proposed as a means of enhancing explanatory clarity and thereby of fostering explanatory progress. The contrastive approach is useful in specifying the exact explanation-seeking questions, and answers to them. Specifying the explanatory claims of a theory also makes it easier to identify questions that are not posed and hence remain unanswered; those constitute a challenge for further theorizing. The case study supports the argument that the precise formulation of explanatory questions promotes explanatory progress.
Geographical Knowledges and Neoliberal Tensions: Compulsory Land Purchase in the Context of Contemporary Urban Redevelopment
Authors: Christophers Brett
Published: April 2010

The author examines the materialization of geographical knowledges in relation to the ongoing neoliberalization of urban space where the latter is based on processes of compulsory land purchase. The specific context for the study is two recently planned commercial redevelopments for the south London borough of Croydon in the United Kingdom, and the arguments mustered in support of these proposals. The author identifies and discusses three principal sets of geographical knowledges, which he examines under the headings symbolic, biopolitical, and scalar. In each case, he shows that the knowledges have strong modernist overtones. The paper seeks both to understand and contextualize these historical connections, and to consider the contemporary political work performed by the knowledges in question.
Globalization from the Edge: A Framework for Understanding How Small and Medium-Sized Firms in the Periphery ‘Go Global’
Authors: Young Nathan
Published: April 2010

The great majority of theoretical and empirical writing on economic globalization continues to focus on urban and semiurban regions, while largely ignoring the vast rural and peripheral spaces of the world. This paper uses research with small and medium-sized enterprises in remote regions of British Columbia, Canada, to develop a way of understanding the unique practices involved in ‘performing’ global economic action from the rural periphery. Specifically, a framework based on insights from three theoretical approaches is advanced—relational network theory, an actor-network approach to distance, and complexity theory in economics—that, in combination, allow the capture of what is unique about efforts to ‘go global’ from marginal geographies.
Music Scenes to Music Clusters: The Economic Geography of Music in the US, 1970–2000
Authors: Florida Richard , Mellander Charlotta , Stolarick Kevin
Published: April 2010

Where do musicians locate, and why do creative industries such as music continue to cluster? This paper analyzes the economic geography of musicians and the recording industry in the US from 1970 to 2000, to shed light on the locational dynamics of music and creative industries more broadly. We examine the role of scale and scope economies in shaping the clustering and concentration of musicians and music industry firms. We argue that these two forces are bringing about a transformation in the geography of both musicians and music industry firms, evidenced in a shift away from regionally clustered, genre-specific music scenes, such as Memphis or Detroit, toward larger regional centers such as New York City and Los Angeles, which offer large markets for music employment and concentrations of other artistic and cultural endeavors that increase demand for musicians. We use population and income to probe for scale effects and look at concentrations of other creative and artistic industries to test for scope effects, while including a range of control variables in our analysis. We use lagged variables to determine whether certain places are consistently more successful at fostering concentrations of musicians and the music industry and to test for path dependency. We find some role for scale and scope effects and that both musicians and the music industry are concentrating in a relatively small number of large regional centers.
Reexamining the Influence of Work and Nonwork Accessibility on Residential Location Choices with a Microanalytic Framework
Authors: Lee Brian H Y , Waddell Paul , Wang Liming , Pendyala Ram M
Published: April 2010

The concept of accessibility has long been theorized as a principal determinant of residential choice behavior. Research on this influence is extensive but the empirical results have been mixed, with some research suggesting that accessibility is becoming a relatively insignificant influence on housing choices. Further, the measurement of accessibility must contend with complications arising from the increasing prevalence of trip chains, nonwork activities, and multiworker households, and also reconcile person-specific travel needs with household residential decisions. With this paper we contribute to the literature by addressing the gap framed by these issues and present a novel residential choice model with three main elements of innovation. First, we operationalize a time–space prism (TSP) accessibility measure, which we believe to be the first application of its kind in a residential choice model. Second, we represent the choice sets in a building-level framework—the lowest level of spatial disaggregation available for modeling residential choices. Third, we explicitly examine the influence of nonwork accessibility at both the local and the person level. This residential choice model is applied in the central Puget Sound region using a 2006 household activity survey. The model estimation results confirm that accessibility remains an important influence, with individual-specific work accessibility as the most critical consideration. By using the TSP approach we establish that nonwork accessibility in a trip-chaining context does contribute to the residential choice decision, even after accounting for work accessibility. Empirical tests also reveal a useful aggregation method to incorporate individual-specific accessibility measures into a household-level choice model.
Regulation of Microtubule Dynamics by Bim1 and Bik1, the Budding Yeast Members of the EB1 and CLIP-170 Families of Plus-End Tracking Proteins
Authors: Blake-Hodek Kristina A. , Cassimeris Lynne , Huffaker Tim C.
Published: April 2010

Microtubule dynamics are regulated by plus-end tracking proteins (+TIPs), which bind microtubule ends and influence their polymerization properties. In addition to binding microtubules, most +TIPs physically associate with other +TIPs, creating a complex web of interactions. To fully understand how +TIPs regulate microtubule dynamics, it is essential to know the intrinsic biochemical activities of each +TIP and how +TIP interactions affect these activities. Here, we describe the activities of Bim1 and Bik1, two +TIP proteins from budding yeast and members of the EB1 and CLIP-170 families, respectively. We find that purified Bim1 and Bik1 form homodimers that interact with each other to form a tetramer. Bim1 binds along the microtubule lattice but with highest affinity for the microtubule end; however, Bik1 requires Bim1 for localization to the microtubule lattice and end. In vitro microtubule polymerization assays show that Bim1 promotes microtubule assembly, primarily by decreasing the frequency of catastrophes. In contrast, Bik1 inhibits microtubule assembly by slowing growth and, consequently, promoting catastrophes. Interestingly, the Bim1-Bik1 complex affects microtubule dynamics in much the same way as Bim1 alone. These studies reveal new activities for EB1 and CLIP-170 family members and demonstrate how interactions between two +TIP proteins influence their activities.
Sarcopenia: European consensus on definition and diagnosis
Authors: Cruz-Jentoft Alfonso J. , Baeyens Jean Pierre , Bauer Jürgen M. , Boirie Yves , Cederholm Tommy , Landi Francesco , Martin Finbarr C. , Michel Jean-Pierre , Rolland Yves , Schneider Stéphane M. , Topinková Eva , Vandewoude Maurits , Zamboni Mauro
Published: April 2010

The European Working Group on Sarcopenia in Older People (EWGSOP) developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia. EWGSOP included representatives from four participant organisations, i.e. the European Geriatric Medicine Society, the European Society for Clinical Nutrition and Metabolism, the International Association of Gerontology and Geriatrics—European Region and the International Association of Nutrition and Aging. These organisations endorsed the findings in the final document.

The group met and addressed the following questions, using the medical literature to build evidence-based answers: (i) What is sarcopenia? (ii) What parameters define sarcopenia? (iii) What variables reflect these parameters, and what measurement tools and cut-off points can be used? (iv) How does sarcopenia relate to cachexia, frailty and sarcopenic obesity?

For the diagnosis of sarcopenia, EWGSOP recommends using the presence of both low muscle mass + low muscle function (strength or performance). EWGSOP variously applies these characteristics to further define conceptual stages as ‘presarcopenia’, ‘sarcopenia’ and ‘severe sarcopenia’. EWGSOP reviewed a wide range of tools that can be used to measure the specific variables of muscle mass, muscle strength and physical performance. Our paper summarises currently available data defining sarcopenia cut-off points by age and gender; suggests an algorithm for sarcopenia case finding in older individuals based on measurements of gait speed, grip strength and muscle mass; and presents a list of suggested primary and secondary outcome domains for research.

Once an operational definition of sarcopenia is adopted and included in the mainstream of comprehensive geriatric assessment, the next steps are to define the natural course of sarcopenia and to develop and define effective treatment.
Titration of Bile Acid Supplements in 3β‐Hydroxy‐Δ5‐C27‐Steroid Dehydrogenase/Isomerase Deficiency
Authors: Riello L , D'Antiga L , Guido M , Alaggio R , Giordano G , Zancan L
Published: April 2010

Objectives:

3β‐Hydroxy‐Δ5‐C27‐steroid dehydrogenase/isomerase deficiency is a bile acid synthesis defect responsive to primary bile acids. We reviewed its clinical features and response to treatment with a mixture of ursodeoxycholic (UDCA) and chenodeoxycholic acid (CDCA) to titrate the dose of supplements required for disease control.

Patients and Methods:

We studied our patients by liquid chromatography‐tandem mass spectrometry, liver function tests, and histology. After diagnosis all of the patients received a balanced mixture of UDCA/CDCA and the dose was titrated according to urinary levels of 3β,7α‐dihydroxy‐5‐cholenoic acid (u‐3β‐D‐OH‐5C).

Results:

Five patients presenting with giant cell hepatitis, biliary cirrhosis, and cryptogenic cirrhosis (1 each), and picked up by neonatal screening (2 patients) were diagnosed at a median age of 2.5 years (range 0.1–5.5). Normal levels of u‐3β‐D‐OH‐5C were achieved after 4 months (range 3–28 months) from the start of the treatment. The minimum dose of UDCA/CDCA required to maintain normal u‐3β‐D‐OH‐5C levels was 5/5 mg · kg−1 · day−1. A follow‐up biopsy in 2 patients showed no progression of liver disease.

Conclusions:

A mixture of UDCA/CDCA can effectively control 3β‐hydroxy‐Δ5‐C27‐steroid dehydrogenase/isomerase deficiency. Dose titration by liquid chromatography‐tandem mass spectrometry warrants the maintenance of negative feedback on the abnormal synthetic pathway and avoids disease progression.
Efficacy of Lactobacillus GG in Aboriginal Children With Acute Diarrhoeal Disease: A Randomised Clinical Trial
Authors: Ritchie Brett K , Brewster David R , Tran Cuong D , Davidson Geoffrey P , McNeil Yvette , Butler Ross N
Published: April 2010

Objective:

The effectiveness of probiotic therapy for acute rotavirus infectious diarrhoea in an indigenous setting with bacterial/parasitic diarrhoea is unclear. In the present study, we assessed the efficacy of probiotics in Australian Aboriginal children in the Northern Territory admitted to hospital with diarrhoeal disease.

Patients and Methods:

A randomised double‐blind placebo‐controlled study was conducted in Aboriginal children (ages 4 months–2 years), admitted to hospital with acute diarrhoeal disease (>3 loose stools per day). Children received either oral Lactobacillus GG (5 × 109 colony‐forming units 3 times per day for 3 days; n = 33) or placebo (n = 31). Small intestinal functional capacity was assessed by the noninvasive 13C‐sucrose breath test on days 1 and 4.

Results:

Both groups showed mean improvement in the sucrose breath test after 4 days; however, there was no difference (mean, 95% confidence interval) between probiotic (2.9 [cumulative percentage of dose recovered at 90 minutes]; 1.7–4.2) and placebo (3.7; 2.3–5.2) groups. Probiotics did not change the duration of diarrhoea, total diarrhoea stools, or diarrhoea score compared with placebo. There was a significant (P < 0.05) difference in diarrhoea frequency on day 2 between probiotics (3.3 [loose stools]; 2.5–4.3) and placebo (4.7; 3.8–5.7) groups.

Conclusions:

Lactobacillus GG did not appear to enhance short‐term recovery following acute diarrhoeal illness in this setting.
Esophageal Motility in Children With Suspected Gastroesophageal Reflux Disease
Authors: Hoffman Ilse , De Greef Toon , Haesendonck Nancy , Tack Jan
Published: April 2010

Background and Objectives:

Motility abnormalities in adults with gastroesophageal reflux disease (GERD) include nontransmitted contractions, reduced distal esophageal contraction amplitude, and simultaneous contractions. Information on esophageal body motility in children with GERD is scarce. Our aim was to study esophageal motility patterns in children with GERD, taking into account the presence of anatomical abnormalities and neurological impairment, the effect of age on esophageal motility in GERD, and the relation between esophageal manometry and GERD severity parameters (acid exposure and presence of esophagitis).

Patients and Methods:

Consecutive children referred for severe GER(D) symptoms underwent a barium swallow, upper endoscopy, pH monitoring, and stationary water‐perfused esophageal manometry.

Results:

Mean lower esophageal sphincter (LES) pressure and velocity of propagation in the proximal and distal esophagus decreased with age in this group of children with GERD (all P < 0.01). Severely disturbed esophageal motility was found in children with previous esophageal atresia. Patients with psychomotor retardation had significantly lower occurrence of peristaltic waves (94% ± 21% vs 79% ± 38%; P = 0.001), distal propagation velocity (0.8 ± 0.4 vs 0.6 ± 0.5 cm/s; P = 0.05), and distal contraction duration (3.1 ± 0.8 vs 3.4 ± 1 seconds; P = 0.05). None of the manometric characteristics differed between patients with normal or abnormal esophageal pH monitoring or with or without erosive esophagitis.

Conclusions:

LES pressure and esophageal velocity decreased with increasing age. Esophageal manometry is severely impaired in children with esophageal atresia and psychomotor retardation. No specific esophageal motor abnormalities related to the presence of endoscopic esophagitis or abnormal pH monitoring were found.
Efficacy and Safety of Pantoprazole Delayed‐release Granules for Oral Suspension in a Placebo‐controlled Treatment‐withdrawal Study in Infants 1–11 Months Old With Symptomatic GERD
Authors: Winter Harland , Kum‐Nji Philip , Mahomedy Suleman H , Kierkus Jaroslaw , Hinz Michelle , Li Huihua , Maguire Mary K , Comer Gail M
Published: April 2010

Objective:

The objective of this study was to assess the efficacy of pantoprazole in infants with gastroesophageal reflux disease (GERD).

Materials and Methods:

Infants ages 1 through 11 months with GERD symptoms after 2 weeks of conservative treatment received open‐label (OL) pantoprazole 1.2 mg · kg−1 · day−1 for 4 weeks followed by a 4‐week randomized, double‐blind (DB), placebo‐controlled, withdrawal phase. The primary endpoint was withdrawal due to lack of efficacy in the DB phase. Mean weekly GERD symptom scores (WGSSs) were calculated from daily assessments of 5 GERD symptoms. Safety was assessed.

Results:

One hundred twenty‐eight patients entered OL treatment, and 106 made up the DB modified intent‐to‐treat population. Mean age was 5.1 months (82% full‐term, 64% male). One third of patients had a GERD diagnostic test before OL study entry. WGSSs at week 4 were similar between groups. WGSSs decreased significantly from baseline during OL therapy (P < 0.001), when all patients received pantoprazole. The decrease in WGSSs was maintained during the DB phase in both treatment groups. There was no difference in withdrawal rates due to lack of efficacy (pantoprazole 6/52; placebo 6/54) or time to withdrawal during the DB phase. The greatest between‐group difference in WGSS was slightly worse with placebo at week 5 (P = 0.09), mainly due to episodes of arching back (P = 0.028). No between‐group differences in adverse event frequency were noted. Serious adverse events in 8 patients were considered unrelated to treatment.

Conclusions:

Pantoprazole significantly improved GERD symptom scores and was well tolerated. However, during the DB treatment phase, there were no significant differences noted between pantoprazole and placebo in withdrawal rates due to lack of efficacy.
Renin‐angiotensin System Activation in Congenital Hepatic Fibrosis in the PCK Rat Model of Autosomal Recessive Polycystic Kidney Disease
Authors: Goto Miwa , Hoxha Nita , Osman Rania , Wen Jessica , Wells Rebecca G , Dell Katherine MacRae
Published: April 2010

Objectives:

Congenital hepatic fibrosis (CHF) is an important cause of morbidity and mortality in patients with autosomal recessive polycystic kidney disease (ARPKD). The pathogenesis of CHF remains undefined. Several recent studies suggest that the renin‐angiotensin system (RAS) is an important mediator of progressive hepatic fibrosis through activation of profibrotic mediators, such as transforming growth factor‐β (TGF‐β). RAS activation has not previously been studied in patients with CHF or in animal models. The aim of the present study was to characterize RAS expression during the course of CHF in the PCK rat.

Materials and Methods:

Studies were conducted in the PCK rat, an orthologous ARPKD/CHF model, and age‐matched normal control Sprague‐Dawley rats. Expression of the RAS components, renin, angiotensinogen, angiotensin‐converting enzyme (ACE), and angiotensin II type 1 receptor (AT1R), as well as the profibrotic mediator TGF‐β, was examined in cystic PCK and control rat livers at 2, 4, and 6 months of age by quantitative real‐time polymerase chain rection (qRT‐PCR). Angiotensin II (ANG II) was examined by immunohistochemistry (IHC). Fibrosis was assessed by IHC using reticulin staining and Masson trichrome. Collagen content was determined by hydroxyproline analysis.

Results:

Progressive fibrosis and increased hepatic collagen content occurred in PCK rats with age. In 4‐ and 6‐month‐old PCK rat livers, ACE gene expression was markedly increased, 8‐ and 17‐fold, respectively, compared with age‐matched control livers. Expression of the other RAS components, renin, angiotensinogen, and AT1R were not significantly different. IHC demonstrated prominent ANG II protein expression in periportal regions in PCK rats. In contrast, no expression was noted in control livers. TGF‐β expression was also increased in PCK rat livers with progressive disease.

Conclusions:

The present study demonstrates, for the first time, RAS upregulation in an orthologous rat ARPKD/CHF model. Increases in ACE and ANG II, as well as the downstream target, the profibrotic mediator TGF‐β, suggest that RAS activation may be an important mediator of CHF disease progression. The findings also suggest that treatment with RAS inhibitors, specifically ACE inhibitors or AT1R blockers, could be therapeutic in slowing disease progression in CHF.
Bilirubin, a Physiological Antioxidant, Can Improve Cryopreservation of Human Hepatocytes
Authors: Galbiati G , Muraca M , Mitry RR , Hughes RD , Lehec SC , Puppi J , Sagias FG , Caruso M , Mieli‐Vergani G , Dhawan A
Published: April 2010

The availability of cryopreserved hepatocytes is required for a more widespread use of hepatocyte transplantation, but human hepatocytes are easily damaged during freezing‐thawing. Here, preincubation with unconjugated bilirubin, a physiological antioxidant, resulted in increased viability and function of hepatocytes (as determined by trypan blue exclusion, mitochondrial succinate dehydrogenases activity, urea synthesis, and cytochrome P450 1A/2) compared with cells incubated without the pigment. These findings suggest that unconjugated bilirubin may be used as cryoprotectant in clinical hepatocyte transplantation.
Association between mammalian lifespan and circadian free-running period: the circadian resonance hypothesis revisited
Authors: Wyse C. A. , Coogan A. N. , Selman C. , Hazlerigg D. G. , Speakman J. R.
Published: April 2010

Biological rhythms that oscillate with periods close to 24 h (circadian cycles) are pervasive features of mammalian physiology, facilitating entrainment to the 24 h cycle generated by the rotation of the Earth. In the absence of environmental time cues, circadian rhythms default to their endogenous period called
tau
, or the free-running period. This sustained circadian rhythmicity in constant conditions has been reported across the animal kingdom, a ubiquity that could imply that innate rhythmicity confers an adaptive advantage. In this study, we found that the deviation of
tau
from 24 h was inversely related to the lifespan in laboratory mouse strains, and in other rodent and primate species. These findings support the hypothesis that misalignment of endogenous rhythms and 24 h environmental cycles may be associated with a physiological cost that has an effect on longevity.
Parasitism may enhance rather than reduce the predatory impact of an invader
Authors: Dick Jaimie T. A. , Armstrong Michael , Clarke Hazel C. , Farnsworth Keith D. , Hatcher Melanie J. , Ennis Marilyn , Kelly Andrew , Dunn Alison M.
Published: April 2010

Invasive species can have profound impacts on communities and it is increasingly recognized that such effects may be mediated by parasitism. The ‘enemy release’ hypothesis posits that invaders may be successful and have high impacts owing to escape from parasitism. Alternatively, we hypothesize that parasites may increase host feeding rates and hence parasitized invaders may have increased community impacts. Here, we investigate the influence of parasitism on the predatory impact of the invasive freshwater amphipod
Gammarus pulex
. Up to 70 per cent of individuals are infected with the acanthocephalan parasite
Echinorhynchus truttae
, but parasitized individuals were no different in body condition to those unparasitized. Parasitized individuals consumed significantly more prey (
Asellus aquaticus
; Isopoda) than did unparasitized individuals. Both parasitized and unparasitized individuals displayed Type-II functional responses (FRs), with the FR for parasitized individuals rising more steeply, with a higher asymptote, compared with unparasitized individuals. While the parasite reduced the fitness of individual females, we predict a minor effect on population recruitment because of low parasite prevalence in the peak reproductive period. The parasite thus has a large
per capita
effect on predatory rate but a low population fitness effect, and thus may enhance rather than reduce the impact of this invader.
Genetic evidence of illegal trade in protected whales links Japan with the US and South Korea
Authors: Baker C. Scott , Steel Debbie , Choi Yeyong , Lee Hang , Kim Kyung Seok , Choi Sung Kyoung , Ma Yong-Un , Hambleton Charles , Psihoyos Louie , Brownell R. L. , Funahashi Naoko
Published: April 2010

We report on genetic identification of ‘whale meat’ purchased in sushi restaurants in Los Angeles, CA (USA) in October 2009 and in Seoul, South Korea in June and September 2009. Phylogenetic analyses of mtDNA cytochromebsequences confirmed that the products included three species of whale currently killed in the controversial scientific whaling programme of Japan, but which are protected from international trade: the fin, sei and Antarctic minke. The DNA profile of the fin whale sold in Seoul established a match to products purchased previously in Japan in September 2007, confirming unauthorized trade between these two countries. Following species identification, these products were handed over to the appropriate national or local authorities for further investigation. The illegal trade of products from protected species of whales, presumably taken under a national permit for scientific research, is a timely reminder of the need for independent, transparent and robust monitoring of any future whaling.
Estimation of measles vaccine efficacy and critical vaccination coverage in a highly vaccinated population
Authors: van Boven Michiel , Kretzschmar Mirjam , Wallinga Jacco , O'Neill Philip D , Wichmann Ole , Hahné Susan
Published: April 2010

Measles is a highly infectious disease that has been targeted for elimination from four WHO regions. Whether and under which conditions this goal is feasible is, however, uncertain since outbreaks have been documented in populations with high vaccination coverage (more than 90%). Here, we use the example of a large outbreak in a German public school to show how estimates of key epidemiological parameters such as the basic reproduction number (R0), vaccine efficacy (VES) and critical vaccination coverage (pc) can be obtained from partially observed outbreaks in highly vaccinated populations. Our analyses rely on Bayesian methods of inference based on the final size distribution of outbreak size, and use data which are easily collected. For the German public school the analyses indicate that the basic reproduction number of measles is higher than previously thought (, 95% credible interval: 23.6–40.4), that the vaccine is highly effective in preventing infection (, 95% credible interval: 0.993–0.999), and that a vaccination coverage in excess of 95 per cent may be necessary to achieve herd immunity (, 95% credible interval: 0.961–0.978). We discuss the implications for measles elimination from highly vaccinated populations.
Characterization of age-related variation in corneal biomechanical properties
Authors: Elsheikh Ahmed , Geraghty Brendan , Rama Paolo , Campanelli Marino , Meek Keith M.
Published: April 2010

An experimental study has been conducted to determine the stress–strain behaviour of human corneal tissue and how the behaviour varies with age. Fifty-seven well-preserved
ex vivo
donor corneas aged between 30 and 99 years were subjected to cycles of posterior pressure up to 60 mm Hg while monitoring their behaviour. The corneas were mechanically clamped along their ring of scleral tissue and kept in physiological conditions of temperature and hydration. The tissue demonstrated hyper-elastic pressure-deformation and stress–strain behaviour that closely matched an exponential trend. Clear stiffening (increased resistance to deformation) with age was observed in all loading cycles, and the rate of stiffness growth was nonlinear with bias towards older specimens. With a strong statistical association between stiffness and age (
p
< 0.05), it was possible to develop generic stress–strain equations that were suitable for all ages between 30 and 99 years. These equations, which closely matched the experimental results, depicted corneal stiffening with age in a form suitable for implementation in numerical simulations of ocular biomechanical behaviour.