bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrations of spatially suspended flexible pipe‐beam with moving fluid
Authors: Prokopowicz Dawid , Bryja Danuta , Woszczyna Anna
Published: March 2009

The nonlinear dynamic model of flexible pipe–beam suspended by spatial system of cables is proposed for vibration analysis of pipeline suspension bridges. The model, based on substructure technique, is considered as an assemblage of the following substructures: cables, hangers and pipe–beam. Equation of motion of pipe–beam is derived by Galerkin's FEM with the original finite element formulated in order to include moving mass of transported fluid. To describe cable vibrations, general continuum approach proposed in Ref.[1] is adopted with application into 3D model. Cable model takes into account initial sag, pre–tension force, large displacements and hangers' point reactions. Equation governing the motion of pipe–beam with cables and hangers is obtained regarding equilibrium conditions of interaction forces and compatibility of displacements at connection points between substructures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular statical calculation of graphene sheet buckling
Authors: Schwarzbart M. , Steindl A. , Troger H.
Published: March 2009

We study the buckling behaviour of a single rectangular graphene layer by a molecular mechanics force field approach. The so called MM3–Potential [1] is used to model the atomistic interactions. The global minimum of the total potential energy is calculated for a prescribed linear displacement field at the edges of the plate. Various buckled configurations depending on the dimension of the plate are calculated and are compared with results from continuum mechanics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of the effective nonlinear material behaviour of composites using X‐FEM ‐ Analysis of the matrix material behaviour
Authors: Kästner Markus , Obst Martin , Thielsch Karin , Brummund Jörg , Ulbricht Volker
Published: March 2009

For a consequent lightweight design the consideration of the nonlinear macroscopic material behaviour of composites, which is amongst others driven by damage and strain–rate effects on the mesoscale, is required. Therefore, the modelling approach using numerical homogenization techniques based on the simulation of representative volume elements which are modelled by the extended finite element method (X–FEM) is currently extended to nonlinear material behaviour. While the glass fibres are assumed to remain linear elastic, a viscoplastic constitutive law accounts for strain–rate dependence and inelastic deformation of the matrix material. This paper describes the process of finding suitable constitutive relations for the polymeric matrix material Polypropylene in the small–strain regime. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Absorption spectra of a donor impurity in a quantum ring
Authors: Xie Wenfang
Published: March 2009

The linear and the third‐order nonlinear optical absorption spectra of a donor impurity confined by a quantum ring are studied using the matrix diagonalization method within the effective‐mass approximation. The linear and the third‐order nonlinear optical absorption coefficients between the ground (L = 0) and the first excited state (L = 1) have been examined based on the computed energies and wavefunctions. The results are presented as a function of the incident photon energy for the different values of the confinement strength, the incident optical density and the ring radius. We found the confinement strength, the incident optical density and the ring radius have a great effect on the linear, the third‐order nonlinear and total absorption spectra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
EXAFS measurements at the micrometer‐scale spatial resolution using achromatic multilayer‐based focusing optics
Authors: Ziegler E. , Aquilanti G. , Mathon O. , de Panfilis S. , van Vaerenbergh P.
Published: March 2009

Spatially resolved EXAFS measurements were performed using micrometer‐size x‐ray beam produced by achromatic Kirkpatrick‐Baez (KB) optical system. The KB mirrors were coated with aperiodic multilayers to increase the collection angle as compared to a total reflection mirror and to provide an energy bandpass (ΔE/E ∼ 15%) sufficient to acquire an EXAFS spectrum without having to adjust the mirror during data acquisition. A series of measurements were performed at various absorption edges including Fe and Pt at the ESRF synchrotron bending‐magnet beamlines BM5 and BM29 to demonstrate the performance of the system within its design energy range (6–13 keV). In particular, the spectra obtained with and without focusing were compared. The relative variation of the size and the position of the microbeam at the sample never exceeded 7% of the beam nominal size, of the order of 1.5 µm. The combination of the large energy range available from a bending‐magnet source with a microfocused achromatic beam could be particularly interesting as a local probe in tandem with a faster yet lower spatial resolution energy‐dispersive EXAFS setup. Copyright © 2009 John Wiley & Sons, Ltd.
Nanostructured Biomaterials with Controlled Properties Synthesis and Characterization
Authors: Teodor Eugenia , Liţescu SimonaCarmen , Petcu C , Mihalache Mihaela , Somoghi Raluca
Published: March 2009

Magnetic nanoparticles were obtained using an adjusted Massart method and were covered in a layer-by-layer technique with hydrogel-type biocompatible shells, from chitosan and hyaluronic acid. The synthesized nanocomposites were characterized using dynamic light scattering, transmission electron microscopy, and Fourier transformed infrared spectroscopy. Biocompatibility of magnetic nanostructures was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) cell proliferation assay, swelling tests, and degradation tests. In addition, interaction of hydrogel-magnetic nanoparticles with microorganisms was studied. The possibility of precise nanoparticles size control, as long as the availability of bio-compatible covering, makes them suitable for biomedical applications.
Belonging at the zoo: retired volunteers, conservation activism and collective identity
Authors: FRASER JOHN , CLAYTON SUSAN , SICKLER JESSICA , TAYLOR ANTHONY
Published: March 2009

The present study affirms previous research findings that volunteering satisfies personal needs but goes further by considering the factor of collective identity for volunteers and its consequences for them. The study specifically focused on older volunteers working at zoos. In the initial phase at Central Park Zoo 30 volunteers completed a short self-completion questionnaire. The second phase involved one-on-one interviews with 21 Bronx Zoo volunteers with a collective self-esteem scale. The responses indicated that the volunteers considered the collective identity of zoo volunteer to be important to their self-concept and believed that this identity is held in high public esteem. The results also suggested that identity as a zoo volunteer not only satisfies personal needs, as found by other volunteer studies, but that the collective identity supports external activism based on shared values. It was concluded that the collective environmental identity facilitated by volunteer work at the zoos provides affirmational social support for the volunteers' work as environmental conservation advocates, and enhances their sense of purpose and self-efficacy.
Happy, stable and contented: accomplished ageing in the imagined futures of young New Zealanders
Authors: PATTERSON LESLEY G. , FORBES KATHERINE E. , PEACE ROBIN M.
Published: March 2009

In imagining how their lives might turn out, 100 young New Zealanders aged between 16 and 18 years wrote descriptions of their future lifecourse. Their descriptions of themselves at the nominal age of 80 years form the basis of the research reported in this paper. For these young people, ageing and old age are understood as accomplishments in the context of an imagined lifecourse. They see personal ageing as shaped by a common temporal ordering of life events that ensures material security, financial success, and an enduring intimate relationship. In imagining themselves aged 80 years, three key themes that constitute a discourse of ‘accomplished ageing’ were identified: the experience of old age would be contingent on achievements throughout the lifecourse; old age would be a time for harvest; and while people may look old they can continue to ‘be’ young. Although their images of bodily appearance included some negative stereotypes of old age, appearance and bodily function were understood as amenable to life-long self-management. The young people imagined themselves as life-long active agents, and framed a positive image and homogeneous social identity for older people. The ‘accomplished ageing’ discourse has implications for how ageing is understood by young people. In particular, the social identity that accomplished ageing implies may shape how they relate to those who do not accomplish ageing in the imagined optimistic and homogeneous way.
Dark Matter Density in Disk Galaxies
Authors: Sellwood J. A.
Published: March 2009

I show that the predicted densities of the inner dark matter halos in ΛCDM models of structure formation appear to be higher than estimates from real galaxies and constraints from dynamical friction on bars. This inconsistency would not be a problem for the ΛCDM model if physical processes that are omitted in the collisionless collapse simulations were able to reduce the dark matter density in the inner halos. I review the mechanisms proposed to achieve the needed density reduction.
The Arcturus Moving Group: Its Place in the Galaxy
Authors: Williams Mary E. K. , Freeman Ken C. , Helmi Amina ,   the RAVE collaboration
Published: March 2009

The Arcturus moving group is a well-populated example of phase space substructure within the disk of our Galaxy. With its large rotational lag (V = −100 kms−1), metal poor nature ([Fe/H] ~ −0.6) and significant age (10 Gyr) it belongs to the Galaxy's thick disk. Traditionally regarded as the remains of a dissolved open cluster, it has recently been suggested to be a remnant of a satellite accreted by our Galaxy.

We confirm via further kinematic studies using the Nordstöm et al. (2004), Schuster et al. (2004) and RAdial Velocity Experiment (RAVE) surveys (Steinmetz et al. 2004) the existence of the group, finding it to possibly favour negative U velocities and also possibly a solar-circle phenomenon. We undertook a high-resolution spectroscopic abundance study of Arcturus group members and candidates to investigate the origin of the group. Examining abundance of Fe, Mg, Ca, Ti, Cr, Ni, Zn, Ce, Nd, Sm and Gd for 134 stars we found that the group is chemically similar to disk stars and does not exhibit a clear chemical homogeneity.

The origin of the group still remains unresolved: the chemical results are consistent with a dynamical origin but do not entirely rule out a merger one. Certainly, the Arcturus group provides a challenge to our understanding of the nature and origin of the Galaxy's thick disk.
Origin of Star-to-Star Abundance Inhomogeneities in Star Clusters
Authors: Palouš Jan , Wünsch Richard , Tenorio-Tagle Guillermo , Silich Sergyi
Published: March 2009

The mass reinserted by young stars of an emerging massive compact cluster shows a bimodal hydrodynamic behaviour. In the inner part of the cluster, it is thermally unstable, while in its outer parts it forms an out-blowing wind. The chemical homogeneity/inhomogeneity of low/high mass clusters demonstrates the relevance of this solution to the presence of single/multiple stellar populations. We show the consequences that the thermal instability of the reinserted mass has to the galactic super-winds.
Warm gas accretion onto the Galaxy
Authors: Bland-Hawthorn J.
Published: March 2009

We present evidence that the accretion of warm gas onto the Galaxy today is at least as important as cold gas accretion. For more than a decade, the source of the bright Hα emission (up to 750 mR†) along the Magellanic Stream has remained a mystery. We present a hydrodynamical model that explains the known properties of the Hα emission and provides new insights on the lifetime of the Stream clouds. The upstream clouds are gradually disrupted due to their interaction with the hot halo gas. The clouds that follow plough into gas ablated from the upstream clouds, leading to shock ionisation at the leading edges of the downstream clouds. Since the following clouds also experience ablation, and weaker Hα (100–200 mR) is quite extensive, a disruptive cascade must be operating along much of the Stream. In order to light up much of the Stream as observed, it must have a small angle of attack (≈ 20°) to the halo, and this may already find support in new Hi observations. Another prediction is that the Balmer ratio (Hα/Hβ) will be substantially enhanced due to the slow shock; this will soon be tested by upcoming WHAM observations in Chile. We find that the clouds are evolving on timescales of 100–200 Myr, such that the Stream must be replenished by the Magellanic Clouds at a fairly constant rate (≳ 0.1 M⊙ yr−1). The ablated material falls onto the Galaxy as a warm drizzle; diffuse ionized gas at 104 K is an important constituent of galactic accretion. The observed Hα emission provides a new constraint on the rate of disruption of the Stream and, consequently, the infall rate of metal-poor gas onto the Galaxy. We consider the stability of Hi clouds falling towards the Galactic disk and show that most of these must break down into smaller fragments that become partially ionized. The Galactic halo is expected to have huge numbers of smaller neutral and ionized fragments. When the ionized component of the infalling gas is accounted for, the rate of gas accretion is ~0.4 M⊙ yr−1, roughly twice the rate deduced from Hi observations alone.
Group infall of substructures on to a Milky Way-like dark halo
Authors: Li Yang-Shyang , Helmi Amina
Published: March 2009

We report the discovery that substructures/subhaloes of a galaxy-size halo tend to fall in together in groups in cosmological simulations, something that may explain the oddity of the MW satellite distribution. The original clustering at the time of infall is still discernible in the angular momenta of the subhaloes even for events which took place up to eight Gyrs ago, z ~ 1. This phenomenon appears to be rather common since at least 1/3 of the present-day subhaloes have fallen in groups in our simulations. Hence, this may well explain the Lynden-Bell & Lynden-Bell ghostly streams. We have also found that the probability of building up a flattened distribution similar to the MW satellites is as high as ~ 80% if the MW satellites were from only one group and ~ 20% when five groups are involved. Therefore, we conclude that the ‘peculiar’ distribution of satellites around the MW can be expected with the CDM structure formation theory. This non-random assignment of satellites to subhaloes implies an environmental dependence on whether these low-mass objects are able to form stars, possibly related to the nature of reionization in the early Universe.
The Challenge of Modelling Galactic Disks
Authors: Burkert Andreas
Published: March 2009

Detailed models of galactic disk formation and evolution require knowledge about the initial conditions under which disk galaxies form, the boundary conditions that affect their secular evolution and the microphysical processes that drive the multi-phase interstellar medium and regulate star formation. Unfortunately, up to now, most of these ingredients are still poorly understood. The challenge therefore is to still construct realistic models of galactic disks with predictive power.
Physiology and behaviour of marine Thioploca
Authors: Høgslund Signe , Revsbech Niels Peter , Kuenen J Gijs , Jørgensen Bo Barker , Gallardo Victor Ariel , Vossenberg Jack , Nielsen Jeppe Lund , Holmkvist Lars , Arning Esther T , Nielsen Lars Peter
Published: March 2009

Among prokaryotes, the large vacuolated marine sulphur bacteria are unique in their ability to store, transport and metabolize significant quantities of sulphur, nitrogen, phosphorus and carbon compounds. In this study, unresolved questions of metabolism, storage management and behaviour were addressed in laboratory experiments with Thioploca species collected on the continental shelf off Chile. The Thioploca cells had an aerobic metabolism with a potential oxygen uptake rate of 1760 μmol O2 per dm3 biovolume per h, equivalent to 4.4 nmol O2 per min per mg protein. When high ambient sulphide concentrations (∼200 μm) were present, a sulphide uptake of 6220±2230 μmol H2S per dm3 per h, (mean±s.e.m., n=4) was measured. This sulphide uptake rate was six times higher than the oxidation rate of elemental sulphur by oxygen or nitrate, thus indicating a rapid sulphur accumulation by Thioploca. Thioploca reduce nitrate to ammonium and we found that dinitrogen was not produced, neither through denitrification nor through anammox activity. Unexpectedly, polyphosphate storage was not detectable by microautoradiography in physiological assays or by staining and microscopy. Carbon dioxide fixation increased when nitrate and nitrite were externally available and when organic carbon was added to incubations. Sulphide addition did not increase carbon dioxide fixation, indicating that Thioploca use excess of sulphide to rapidly accumulate sulphur rather than to accelerate growth. This is interpreted as an adaptation to infrequent high sulphate reduction rates in the seabed. The physiology and behaviour of Thioploca are summarized and the adaptations to an environment, dominated by infrequent oxygen availability and periods of high sulphide abundance, are discussed.
Hepatic Gene Expression in Morbidly Obese Women: Implications for Disease Susceptibility
Authors: Elam Marshall B. , Cowan George S. , Rooney Robert J. , Hiler M. Lloyd , Yellaturu Chandrahasa R. , Deng Xiong , Howell George E. , Park Edwards A. , Gerling Ivan C. , Patel Divyan , Corton J. Christopher , Cagen Lauren M. , Wilcox Henry G. , Gandhi Malay , Bahr Micheal H. , Allan Micheal C. , Wodi Linus A. , Cook George A. , Hughes Thomas A. , Raghow Rajendra
Published: March 2009

The objective of this study was to determine the molecular bases of disordered hepatic function and disease susceptibility in obesity. We compared global gene expression in liver biopsies from morbidly obese (MO) women undergoing gastric bypass (GBP) surgery with that of women undergoing ventral hernia repair who had experienced massive weight loss (MWL) following prior GBP. Metabolic and hormonal profiles were examined in MO vs. MWL groups. Additionally, we analyzed individual profiles of hepatic gene expression in liver biopsy specimens obtained from MO and MWL subjects. All patients underwent preoperative metabolic profiling. RNAs were extracted from wedge biopsies of livers from MO and MWL subjects, and analysis of mRNA expression was carried out using Affymetrix HG‐U133A microarray gene chips. Genes exhibiting greater than twofold differential expression between MO and MWL subjects were organized according to gene ontology and hierarchical clustering, and expression of key genes exhibiting differential regulation was quantified by real‐time–polymerase chain reaction (RT‐PCR). We discovered 154 genes to be differentially expressed in livers of MWL and MO subjects. A total of 28 candidate disease susceptibility genes were identified that encoded proteins regulating lipid and energy homeostasis (PLIN, ENO3, ELOVL2, APOF, LEPR, IGFBP1, DDIT4), signal transduction (MAP2K6, SOCS‐2), postinflammatory tissue repair (HLA‐DQB1, SPP1, P4HA1, LUM), bile acid transport (SULT2A, ABCB11), and metabolism of xenobiotics (GSTT2, CYP1A1). Using gene expression profiling, we have identified novel candidate disease susceptibility genes whose expression is altered in livers of MO subjects. The significance of altered expression of these genes to obesity‐related disease is discussed.
Measurement of pH
Authors: Lawn Richard , Prichard Elizabeth
Published: March 2009

Whether pH is being used to test a sample against a legal requirement or specification; as part of an analytical method; for monitoring and controlling a reaction; as a process control in the chemical industry; or for the environmental monitoring of waste and effluents, it is important that all pH measurements are carried out in a logical and consistent manner, paying careful attention to experimental procedures, in order to obtain reliable results. This guide provides scientists with the knowledge of how to do just that, first by outlining the principles of pH measurement and buffer solutions. pH meters and electrodes are then discussed, including selection criteria and the care of electrodes. Finally, sections on making pH measurements and uncertainty are followed by a set of practical exercises. Measurement of pH is one of the Practical Laboratory Skills Training Guides, a series that aims to make achieving best practice easy. These invaluable manuals will enable both experienced and inexperienced staff to get the essential basics of any experiment right simply by following the clear and easy to use instructions provided. The guides are written by experienced scientists and include minimal theory, plenty of practical exercises in order to assess competence, and trouble shooting information. Other titles are: Measurement of Mass; Measurement of Volume; High Performance Liquid Chromatography; and Gas Chromatography.
Synthesis and high thermoelectric efficiency of Zintl phase YbCd2−xZnxSb2
Authors: Wang Xiao-Jun , Tang Mei-Bo , Chen Hao-Hong , Yang Xin-Xin , Zhao Jing-Tai , Burkhardt Ulrich , Grin Yuri
Published: March 2009

We synthesized a series of polycrystalline YbCd2−xZnxSb2 (x=0, 0.4, 0.8, 1, 1.2, 1.6, and 2) samples and measured their thermoelectric properties. Thermoelectric figure of merit ZT at 700K is higher than 1.0 for Cd-rich samples (x=0, 0.4, 0.8, and 1.0) and Zn substitute of Cd in YbCd2Sb2 can easily tune carrier concentration and reduce thermal conductivity. When x=0.4, sample exhibits the highest power factor (12–20μWcm−1K−2), the lowest lattice thermal conductivity (1.0Wm−1K−1 at 300K), highest ZT (1.2 at 700K), and best “self-compatibility.” The first principles calculations were performed to study the influences of bonding and electronic structures on physical properties.
Phase behaviors of diblock copolymer-nanoparticle films under nanopore confinement
Authors: Yang Qinghua , Li Ming , Tong Chaohui , Zhu Yuejin
Published: March 2009

We employ self-consistent-field and density-functional theories to simulate the phase behaviors of diblock copolymer-nanoparticle mixtures confined in a two-dimensional circular pore. By varying the block ratio, the size of the pore, and the particle concentration, rich phase structures are discovered. It is shown that the structural frustration, the loss of conformational entropy of the polymer chains under confinement, the curvature of the pore, and the steric packing effect of the particles play important roles in determining the morphologies of the nanocomposites under circular confinement. It is found that the increase in the particle concentration can promote the transformation of concentric lamellas to the cylindrical domains. Our results suggest effective ways to stabilize the phase orderings of diblock copolymer-nanoparticle mixtures under two-dimensional circular confinement.
Experimental and theoretical investigation of cubic FeCo nanoparticles for magnetic hyperthermia
Authors: Jing Ying , Sohn Hweerin , Kline Timothy , Victora Randall H. , Wang Jian-Ping
Published: March 2009

Magnetic nanoparticles have great potential as heating elements for use in magnetic hyperthermia for cancer therapy and drug release. A problem with widely used magnetite and mag-hematite nanoparticles is the relatively low magnetization, which results in low heating efficiency. Here high-magnetic-moment Fe70Co30 nanoparticles with a cubic shape were synthesized using a gas condensation sputtering technique for potential magnetic hyperthermia application. The mean size of nanoparticles was 12 nm with 13.6% standard deviation. Micromagnetic simulation of particles’ experimental hysteresis loop suggests that their behavior is dominated by a uniaxial anisotropy.
The multinomial simulation algorithm for discrete stochastic simulation of reaction-diffusion systems
Authors: Lampoudi Sotiria , Gillespie Dan T. , Petzold Linda R.
Published: March 2009

The Inhomogeneous Stochastic Simulation Algorithm (ISSA) is a variant of the stochastic simulation algorithm in which the spatially inhomogeneous volume of the system is divided into homogeneous subvolumes, and the chemical reactions in those subvolumes are augmented by diffusive transfers of molecules between adjacent subvolumes. The ISSA can be prohibitively slow when the system is such that diffusive transfers occur much more frequently than chemical reactions. In this paper we present the Multinomial Simulation Algorithm (MSA), which is designed to, on the one hand, outperform the ISSA when diffusive transfer events outnumber reaction events, and on the other, to handle small reactant populations with greater accuracy than deterministic-stochastic hybrid algorithms. The MSA treats reactions in the usual ISSA fashion, but uses appropriately conditioned binomial random variables for representing the net numbers of molecules diffusing from any given subvolume to a neighbor within a prescribed distance. Simulation results illustrate the benefits of the algorithm.
Electron spin resonance studies of Bi0.55Ca0.45MnO3 nanoparticles
Authors: Kurian Joji , Singh R
Published: March 2009

Temperature dependent electron spin resonance (ESR) studies were carried out on two samples of Bi0.55Ca0.45MnO3 (grain size 21 and 15 nm) synthesized by sol-gel process and compared with the studies on corresponding bulk sample. The double integrated intensity and linewidth (ΔH) of the ESR signal verses temperature is used to get information about magnetic interactions and values of Charge-Ordering temperature, TCO and Néel temperature, TN. The TCO value decreases from 313K for bulk to 306K for 15 nm size sample. The TN values remain around 153 K for all the samples. The magnetic phase for T>TCO is dominated by ferromagnetic (FM) correlations which can be attributed to activated Mn3+–Mn4+ hopping of a small polaron. In the temperature range TCO>T>TN, the domains of FM and antiferromagnetic (AFM) spin correlations coexist. The FM phase volume decreases and the paramagnetic (PM)-PM+charge ordered (CO) and (PM+CO)−(AFM+CO) transitions become sharp with decrease in grain size. The critical exponent for PM-AFM transition for the charge ordered sample with grain size 15 nm is incidentally found to be close to the theoretically predicted value for plain PM to AFM transition. The Griffiths phase physics is found to be an appropriate theoretical model for describing the ESR data in the present system.
A new quantum control scheme for multilevel systems based on effective decomposition by intense laser fields
Authors: Sugawara M.
Published: March 2009

A new quantum control scheme for general multilevel systems using intense laser fields is proposed. In the present scheme, the target subspace consisting of several quantum levels is effectively isolated by applying intense cw lasers with specific conditions. The formulation is carried out using the Green function with the help of projection operator method. Dynamics of the isolated target subspace is governed by an effective Hamiltonian. The developed scheme is applied to the quantum control of dissipative four- and five-level systems. It is clarified that the present method makes it possible not only to manipulate the coherent population dynamics but also to suppress the dissipative dynamics.
Fe-Al interface intermixing and the role of Ti, V, and Zr as a stabilizing interlayer at the interface
Authors: Priyantha W. , Smith R. J. , Chen H. , Kopczyk M. , Lerch M. , Key C. , Nachimuthu P. , Jiang W.
Published: March 2009

Fe-Al bilayer interfaces with and without interface stabilizing layers (Ti, V, Zr) were fabricated using dc magnetron sputtering. Intermixing layer thickness and the effectiveness of the stabilizing layer (Ti, V, Zr) at the interface were studied using Rutherford backscattering spectrometry (RBS) and x-ray reflectometry (XRR). The result for the intermixing thickness of the AlFe layer is always higher when Fe is deposited on Al as compared to when Al is deposited on Fe. By comparing measurements with computer simulations, the thicknesses of the AlFe layers were determined to be 20.6 Å and 41.1 Å for Al/Fe and Fe/Al bilayer systems, respectively. The introduction of Ti and V stabilizing layers at the Fe-Al interface reduced the amount of intermixing between Al and Fe, consistent with the predictions of model calculations. The Zr interlayer, however, was ineffective in stabilizing the Fe-Al interface in spite of the chemical similarities between Ti and Zr. In addition, analysis suggests that the Ti interlayer is not effective in stabilizing the Fe-Al interface when the Ti interlayer is extremely thin (∼3 Å) for these sputtered metallic films.
High-power millimeter-wave rotary joint
Authors: Chang T. H. , Yu B. R.
Published: March 2009

The rotary joint is a useful microwave component that connects a fixed part to a rotatable part. This study systematically analyzes the effect of the discontinuity on the interface of a rotary joint for several waveguide modes. Simulation results indicate that the transmission of the TE01 mode is independent of the geometry of the joint, and thus is ideal for such application. A rotary joint consisting of two identical TE01 mode converters, clasped each other by a bearing, is designed, fabricated, and tested. Back-to-back transmission measurements exhibit an excellent agreement to the results of computer simulations. The measured optimum transmission is 97% with a 3 dB bandwidth of 8.5 GHz, centered at 35.0 GHz. The cold measurement shows that the results are independent of the angle of rotation. In addition, a high-power experiment is conducted. The just developed rotary joint can operate up to a peak input power of 210 W with a duty of 18%. The working principle, although demonstrated in the millimeter-wave region, can be applied up to the terahertz region where the joint gap is generally critical except for the operating TE01 mode.
Laser-embossing nanoparticles into a polymeric film
Authors: Skirtach Andre G. , Kurth Dirk G. , Möhwald Helmuth
Published: March 2009

Embossing or embedding of nanoparticles into a polymeric film is realized by an electromagnetic field. Upon laser light illumination nanoparticles absorb energy, convert it to heat, and sink into a locally softened polymer film as probed by atomic force microscope. The polymeric matrix forms a characteristic rim and surrounds the lower part of the nanoparticles; the upper part of the nanoparticles is left unexposed to the ambient phase. This imprinting method is thought to have an impact on ultrahigh-density data storage, measurements of fundamental thermal parameters of materials, and fabrication of asymmetrical, Janus-type nanoparticles.
Membrane-associated farnesylated UCH-L1 promotes α-synuclein neurotoxicity and is a therapeutic target for Parkinson's disease
Authors: Liu Zhihua , Meray Robin K. , Grammatopoulos Tom N. , Fredenburg Ross A. , Cookson Mark R. , Liu Yichin , Logan Todd , Lansbury Peter T.
Published: March 2009

Ubiquitin C-terminal hydrolase-L1 (UCH-L1) is linked to Parkinson's disease (PD) and memory and is selectively expressed in neurons at high levels. Its expression pattern suggests a function distinct from that of its widely expressed homolog UCH-L3. We report here that, in contrast to UCH-L3, UCH-L1 exists in a membrane-associated form (UCH-L1
M
) in addition to the commonly studied soluble form. C-terminal farnesylation promotes the association of UCH-L1 with cellular membranes, including the endoplasmic reticulum. The amount of UCH-L1
M
in transfected cells is shown to correlate with the intracellular level of α-synuclein, a protein whose accumulation is associated with neurotoxicity and the development of PD. Reduction of UCH-L1
M
in cell culture models of α-synuclein toxicity by treatment with a farnesyltransferase inhibitor (FTI-277) reduces α-synuclein levels and increases cell viability. Proteasome function is not affected by UCH-L1
M
, suggesting that it may negatively regulate the lysosomal degradation of α-synuclein. Therefore, inhibition of UCH-L1 farnesylation may be a therapeutic strategy for slowing the progression of PD and related synucleinopathies.
Phasic excitation of dopamine neurons in ventral VTA by noxious stimuli
Authors: Brischoux Frédéric , Chakraborty Subhojit , Brierley Daniel I. , Ungless Mark A.
Published: March 2009

Midbrain dopamine neurons play central roles in reward processing. It is widely assumed that all dopamine neurons encode the same information. Some evidence, however, suggests functional differences between subgroups of dopamine neurons, particularly with respect to processing nonrewarding, aversive stimuli. To directly test this possibility, we recorded from and juxtacellularly labeled individual ventral tegmental area (VTA) dopamine neurons in anesthetized rats so that we could link precise anatomical position and neurochemical identity with coding for noxious stimuli. Here, we show that dopamine neurons in the dorsal VTA are inhibited by noxious footshocks, consistent with their role in reward processing. In contrast, we find that dopamine neurons in the ventral VTA are phasically excited by footshocks. This observation can explain a number of previously confusing findings that suggested a role for dopamine in processing both rewarding and aversive events. Taken together, our results indicate that there are 2 functionally and anatomically distinct VTA dopamine systems.
The importance of maternal BMI on infant's birth weight in four BMI groups for the period 1978–2001
Authors: BRYNHILDSEN JAN , SYDSJÖ ADAM , EKHOLM‐SELLING KATARINA , JOSEFSSON ANN
Published: March 2009

Objective. To study whether increased maternal weight and other factors of importance is associated with higher birth weights of the children over a period of almost 25 years. Design. Retrospective cohort study. Setting. Delivery wards in southeast Sweden. Sample. A total of 4,330 delivered women and their children from the years 1978, 1986, 1992, 1997, and 2001. Methods. Analysis of covariance was used to evaluate the importance of the mother's body mass index (BMI) on the children's birth weights during the study years and smoking, parity, employment, gestational age, and the age of the mothers were adjusted for. Main outcome measures. Weight of the offspring in relation to maternal BMI and possible confounders such as smoking, parity, employment, gestational age, and the age of the mother. Results. Between 1978 and 1992, there was an increase in birth weight in each of the four BMI categories (i.e. BMI<20, 20–24.9, 25–29.9 and ≥30, respectively) even after adjustments were made for relevant background characteristics (p<0.001). However, between 1992 and 2001, the birth weight for children whose mothers had a BMI of less than 20 or between 20 and 24.9 decreased (p<0.001). For almost every study year, the mothers’ BMI was of significant influence on the children's birth weights. However, the proportion of variance explained by the models (i.e. the adjusted R2) was not substantially altered when the mother's BMI was excluded from the models. Conclusion. Maternal BMI is of significance to explain trends in infants’ birth weight over time, but not of sole importance.
Quantum teleportation and entanglement swapping with linear optics logic gates
Authors: Schmid Christian , Kiesel Nikolai , Weber Ulrich K , Ursin Rupert , Zeilinger Anton , Weinfurter Harald
Published: March 2009

We report on the usage of a linear optics phase gate for distinguishing all four Bell states simultaneously in a quantum teleportation and entanglement swapping protocol. This is demonstrated by full-state tomography of the one- and two-qubit output states of the two protocols, yielding average state fidelities of about 0.83 and 0.77, respectively. In addition, the performance of the teleportation channel is characterized by the quantum process tomography. The non-classical properties of the entanglement swapping output states are further confirmed by the violation of a CHSH-type Bell inequality of 2.14 on average.
Condensin Regulates the Stiffness of Vertebrate Centromeres
Authors: Ribeiro Susana A. , Gatlin Jesse C. , Dong Yimin , Joglekar Ajit , Cameron Lisa , Hudson Damien F. , Farr Christine J. , McEwen Bruce F. , Salmon Edward D. , Earnshaw William C. , Vagnarelli Paola
Published: March 2009

When chromosomes are aligned and bioriented at metaphase, the elastic stretch of centromeric chromatin opposes pulling forces exerted on sister kinetochores by the mitotic spindle. Here we show that condensin ATPase activity is an important regulator of centromere stiffness and function. Condensin depletion decreases the stiffness of centromeric chromatin by 50% when pulling forces are applied to kinetochores. However, condensin is dispensable for the normal level of compaction (rest length) of centromeres, which probably depends on other factors that control higher-order chromatin folding. Kinetochores also do not require condensin for their structure or motility. Loss of stiffness caused by condensin-depletion produces abnormal uncoordinated sister kinetochore movements, leads to an increase in Mad2(+) kinetochores near the metaphase plate and delays anaphase onset.
Bayesian survey-based assessment of North Sea plaice (Pleuronectes platessa): extracting integrated signals from multiple surveys
Authors: Bogaards Johannes A. , Kraak Sarah B. M. , Rijnsdorp Adriaan D.
Published: March 2009

Bogaards, J. A., Kraak, S. B. M., and Rijnsdorp, A. D. 2009. Bayesian survey-based assessment of North Sea plaice (Pleuronectes platessa): extracting integrated signals from multiple surveys. – ICES Journal of Marine Science, 66: 665–679. Dependence on a relatively small sample size is generally viewed as a big disadvantage for survey-based assessments. We propose an integrated catch-at-age model for research vessel data derived from multiple surveys, and illustrate its utility in estimating trends in North Sea plaice abundance and fishing mortality. Parameter estimates were obtained by Bayesian analysis, which allows for estimation of uncertainty in model parameters attributable to measurement error. Model results indicated constant fishing selectivity over the distribution area of the North Sea plaice stock, with decreased selectivity at older age. Whereas separate analyses of survey datasets suggested different biomass trends in the southeast than in the western and central North Sea, a combined analysis demonstrated that the observations in both subareas were compatible and that spawning-stock biomass has been increasing over the period 1996–2005. The annual proportion of fish that dispersed in a northwesterly direction was estimated to increase from about 10% at age 2 to 33% at age 5 and older. We also found higher fishing mortality rates than reported in ICES assessments, which could be the consequence of inadequate specification of catchability-at-age in this study or underestimated fishing mortality by the conventional ICES assessment, which relies on official landings figures.
Dynamic Interaction of Craniofacial Structures during Head Positioning and Direct Laryngoscopy in Anesthetized Patients with and without Difficult Laryngoscopy
Authors: Kitamura Yuji , Isono Shiroh , Suzuki Noriko , Sato Yumi , Nishino Takashi
Published: March 2009

Background

We lack fundamental knowledge of the mechanisms of difficult laryngoscopy despite its clinical significance. The aim of this study was to examine how head positioning and direct laryngoscopy alter arrangements of craniofacial structures.

Methods

Digital photographs of the lateral view of the head and neck were taken at each step of head positioning and direct laryngoscopy in age- and body mass index-matched patients with (n = 13) and without (n = 13) difficult laryngoscopy during general anesthesia with muscle paralysis. The images were used for measurements of various craniofacial dimensions.

Results

Both simple neck extension and the sniffing position produced a caudal shift of the mandible and a downward shift of the larynx, resulting in an increase of the submandibular space. Direct laryngoscopy during the sniffing position displaced the mandible and tongue base upward and caudally, and the larynx downward and caudally, increasing the submandibular space and facilitating vertical arrangement of the mandible, tongue base, and larynx to the facial line. These structural arrangements in response to direct laryngoscopy were not observed in patients with difficult laryngoscopy, whereas head positioning produced similar structural arrangements in patients with and without difficult laryngoscopy.

Conclusion

Increase in the submandibular space and a vertical arrangement of the mandible, tongue base, and larynx to the facial line seem to be important mechanisms for improving the laryngeal view during head positioning and direct laryngoscopy. Failure of these structural arrangements in response to direct laryngoscopy may result in difficult laryngoscopy.
Monitoring of the Sublingual Microcirculation in Cardiac Surgery Using Orthogonal Polarization Spectral Imaging
Authors: Bauer Andreas , Kofler Sieglinde , Thiel Manfred , Eifert Sandra , Christ Frank
Published: March 2009

Background

The recent introduction of orthogonal polarization spectral imaging enables the direct visualization of the microcirculation of man without imaging enhancing dyes. The authors studied the changes in microvascular perfusion of sublingual mucosa during cardiac surgery with the use of cardiopulmonary bypass (CPB) using this optical method.

Method

Orthogonal polarization spectral images were recorded in 47 patients after skin incision (T1), after the start of CPB (T2), in the late phase of CPB (T3), and 1 h after the discontinuation of CPB (T4). The images were analyzed for microvascular diameter, erythrocyte velocity, and functional capillary density using an established analysis routine for intravital microscopy studies. In a subpopulation (n = 8), the expression of the adhesion molecules CD18 on circulation leukocytes was compared with the number of visualized rolling leukocytes.

Results

Preoperatively, no significant changes of the microvascular diameter and erythrocyte velocity were seen. The functional capillary density was significantly reduced at T3 to 90% of the values observed before CPB but recovered at T4 and showed a weak but significant correlation with body temperature (r = 0.38, P < 0.01) and hemoglobin concentration (r = 0.20, P < 0.05). Expression of CD18 was significantly increased in the late phase of CPB (T3) only, whereas the numbers of rolling leukocytes increased during CPB and revealed a significant threefold increase 1 h after termination of CPB.

Conclusions

Orthogonal polarization spectral imaging revealed no major changes of microvascular perfusion during uncomplicated hypothermic CPB. The slightly reduced functional capillary density during CPB may be caused by several factors all present during CPB, including hypothermia, the artificial extracorporeal perfusion, surgical trauma, hemodilution, and inflammatory reaction. The current data do not allow differentiation between the effects of those possible causes.
Nitrosative Stress and Myocardial Sarcoplasmic Endoreticular Calcium Adenosine Triphosphatase Subtype 2a Activity after Lung Resection in Swine
Authors: Heerdt Paul M. , Lane Paul , Pan Brian Y. , Schaefer Ulrich , Crabtree Mark , Hong Roger , Singer Andrew A. M. , Levi Roberto , Park Bernard J.
Published: March 2009

Background

Chronic, disease-associated oxidative stress induces myocardial peroxynitrite formation that may lead to nitrosative inhibition of the calcium cycling protein sarcoplasmic endoreticular calcium adenosine triphosphatase subtype 2a (SERCA2a). The current study was designed to test the hypothesis that the acute oxidative stress associated with lung resection also induces myocardial nitrosative stress and alters SERCA2a activity.

Methods

Ventricular myocardium from 16 swine was studied; 11 animals had undergone left upper lobectomy (n = 7) or sham thoracotomy (n = 4) 3 days before harvest, and 5 were nonoperated controls. Tissue peroxynitrite was assessed by measurement of 3-nitrotyrosine incorporation into proteins. SERCA2a activity was determined from indo-1 uptake by isolated sarcoplasmic reticular membranes. Expression of SERCA2a and its regulatory protein phospholamban were determined by Western blotting, as was the phospholamban phosphorylation state (when dephosporylated, phospholamban inhibits SERCA2a). Mechanical significance of changes in SERCA2a activity was assessed from the force-frequency relation of isometric myocardial trabeculae.

Results

Relative to both the control and sham groups, lobectomy animals exhibited a greater than twofold higher myocardial 3-nitrotyrosine incorporation and an approximately 50% lower SERCA2a activity, but no difference in SERCA2a or phospholamban expression or phospholamban phosphorylation. Concomitantly, whereas the trabecular force-frequency relation of control animals was positive, that of lobectomy animals was negative, consistent with impaired calcium cycling.

Conclusions

These data indicate that oxidative/nitrosative stress associated with lung resection influences SERCA2a activity independent of any influence on protein expression or phospholamban phosphorylation. The findings link an acute event with a subcellular process primarily described for chronic illness and suggest a biochemical basis for perioperative changes in myocardial mechanical reserve.
An Evolutionarily Conserved Presynaptic Protein Is Required for Isoflurane Sensitivity in Caenorhabditis elegans
Authors: Metz Laura B. , Dasgupta Nupur , Liu Christine , Hunt Stephen J. , Crowder C Michael
Published: March 2009

Background

Volatile general anesthetics inhibit neurotransmitter release by an unknown mechanism. A mutation in the presynaptic soluble NSF attachment protein receptor (SNARE) protein syntaxin 1A was previously shown to antagonize the anesthetic isoflurane in Caenorhabditis elegans. The mechanism underlying this antagonism may identify presynaptic anesthetic targets relevant to human anesthesia.

Methods

Sensitivity to isoflurane concentrations in the human clinical range was measured in locomotion assays on adult C. elegans. Sensitivity to the acetylcholinesterase inhibitor aldicarb was used as an assay for the global level of C. elegans neurotransmitter release. Comparisons of isoflurane sensitivity (measured by the EC50) were made by simultaneous curve fitting and F test as described by Waud.

Results

Expression of a truncated syntaxin fragment (residues 1-106) antagonized isoflurane sensitivity in C. elegans. This portion of syntaxin interacts with the presynaptic protein UNC-13, suggesting the hypothesis that truncated syntaxin binds to UNC-13 and antagonizes an inhibitory effect of isoflurane on UNC-13 function. Consistent with this hypothesis, overexpression of UNC-13 suppressed the isoflurane resistance of the truncated syntaxins, and unc-13 loss-of-function mutants were highly isoflurane resistant. Normal anesthetic sensitivity was restored by full-length UNC-13, by a shortened form of UNC-13 lacking a C2 domain, but not by a membrane-targeted UNC-13 that might bypass isoflurane inhibition of membrane translocation of UNC-13. Isoflurane was found to inhibit synaptic localization of UNC-13.

Conclusions

These data show that UNC-13, an evolutionarily conserved protein that promotes neurotransmitter release, is necessary for isoflurane sensitivity in C. elegans and suggest that its vertebrate homologs may be a component of the general anesthetic mechanism.