bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a Direct-Drive XY Table System: Electromechanical and Dynamic Optimization
Authors: Ma Zhi Peng , Zhao Xing Yu , Wang Fu Jun , Zhang Da Wei
Published: September 2011

This paper presents the electromechanical system modeling of a direct-drive precision positioning XY table used for wire bonding. The XY table is directly driven by voice coil actuator (VCA) and therefore the equivalent circuit of VCA was built to construct the co-simulation platform of electromechanical system. By use of finite element analysis (FEA) and co-simulation method based on ADAMS and MATLAB/SIMULINK software, the spring as the key component in the decoupling mechanism was optimized and the matching law of stiffness and preload was given. The mechanical model of decoupling mechanism was then built up and the matching law was validated by theoretical analysis. The damp-spring-mass system of y-axis table further illustrated the matching law. For the complex electromechanical coupling system, the method of co-simulation could reflect the actual properties of system better compared with the oversimplified analytical model. The achieved results would be helpful to the dynamic design of the kind of manufacturing equipment and provide theoretical guidance for the control system development and testing.
Research on Structural Design and Optimization of Artificial Optical Compound Eye
Authors: Chen M.J. , Chu Xin , Wu Chun Ya , Jiang Y.
Published: September 2011

A novel curved artificial optical compound eye structure is proposed, which needs to be manufactured by ultra-precision machining due to the application of aspheric in the design. In this artificial compound eye, each of the micro-lens has an aspheric surface instead of spherical surface, which leads to a reduction of spherical aberration from 400μm to 75μm. The focal length of micro-lens is decided by its own position and equals to the distance between base surface and image receiver. The sructural parameters of micro-lens were calculated according to the theory of geometrical optics. The model of artificial compound eye was built and verified by ray tracing. Finally, the result shows that the novel curved artificial compound eye can improve imaging resolution and imaging quality at the edge effectively, and the proposed structure is feasible.
Influence of Alignment Errors on Measuring Nose Roundness of Diamond Cutting Tools with a Novel Method
Authors: Li Z.Q. , Sun Tao , Zong Wen Jun , Zhao Xue Sen , Dong Shen
Published: September 2011

The nose roundness is one of the most important indexes of lapping quality of rounded diamond cutting tools. Due to its special characters and requirements, a new measuring method was proposed based on atomic force microscope (AFM) and precision-revolution spindle. However, in the measurement the alignment errors of tools with the spindle axis have great influence on the measuring result. By a carefully deducting, the relations between the deviation and the alignment errors were presented. The deviation increases with the eccentric linearly, and has the same value with the eccentric. But it varies with θ dramatically and forms a parabola curve when the deflection angle is negative, otherwise, varies with θ gently and forms a flat Gaussian curve.
A Theoretical Estimation of the Charge Density Distribution in the Diluted Magnetic Semiconductors of Si1-xMx and Ge1-xMx (M = V, Mn, Co)
Authors: Sheeba R.A.J.R. , Saravanan R. , Berchmans L. John
Published: September 2011

An effort has been made to understand the charge density distribution of the Si and Ge based diluted magnetic semiconductors. A theoretical analysis has been done on the variation of charge densities when the semiconductors Si and Ge are doped with the transition metal atoms of V, Mn and Co with different concentrations of x (0.02, 0.04, 0.06, 0.08, and 0.10), in Si1-xMx and Ge1-xMx. Two dimensional electron density contour maps have been plotted for all the compositions studied in this work. The theoretical mid bond densities were found out for the compounds which can be taken as the reference values for comparison of the experimental values of the same compositions.
Copper (II) Complexes of Knoevenagel Condensate β-Diketimines as Models for Blue Copper and their Interaction with DNA
Authors: Malarvizhi M. , Athappan PR.
Published: September 2011

A series of copper(II) complexes with positive reduction potential have been synthesized by anin situfashion by the reaction of a Knoevenagel condensate, salicylidenebenzoylacetone (salbenz) with 4-X-anilines and copper(II) chloride. The electronic spectra of these complexes in acetonitrile show d–d bands around 540 nm with high molar extinction coefficient (ε~1600-1800 cm-1) due to lowering of symmetry around metal center, and MLCT band around 400 nm. The EPR spectral features with four g((lines having g((>2.0 >g⊥, and a broadening of g⊥component suggest a lowered site symmetry around Cu(II) monomer. The cyclic voltammetric studies of Cu(II) complexes in CH3CN shows a positive reduction potential (Epc = 492-451 mV) with moderately high peak to peak separation (∆Ep=126-163mV). All these results are comparable with the results of natural blue copper proteins even in the absence of S-coordination, and suggest that they can mimic the functional properties of blue copper proteins. These complexes on interaction with herring sperm DNA, the intense intraligand (IL) π-π*transition around 300 nm is found to be hypochromic with a slight red shift. The hypochromism and moderate binding constant are indicative of binding of the complexes with DNA with an affinity less than the classical intercalators, due to the possible substitution of the two chlorides with the DNA base pairs and relatively bulky structure of ligand molecule. Additional evidence of DNA-Cu(II) complex interaction was obtained by CD studies. The experimental results reveal that these complexes may serve as a model for blue copper proteins and as a tool for probing the structure of DNA.
Review on Magnesium Indium Oxide Thin Films: Material Properties and Preparation Techniques
Authors: Anuradha B. , Sanjeeviraja C.
Published: September 2011

Thin films of pure metals, alloys, semiconductors and organic compounds are indispensable tools in industry, which anticipate and recognize novel functional materials for the development of microelectronics. Thin film technology makes it possible to deposit ultra-thin functional material layers on a base substrate to form many active and passive micro-miniaturized components and devices such as solar cells, radiation sources, sensors, magnetic devices, bolometers, switching devices, photodiodes, digital versatile disk (DVD), flat panel display etc. Thus thin films play a dominant role in modern technology like opto-electronics, microelectronics etc. The study of surfaces and thin films overlaying them has been carried out for many years. But recently, it has become increasingly important in several fields of study. Thin film properties such as optical, electrical and magnetic properties are very much interested in research areas. Thin film properties are strong dependent on the method of deposition, the substrate materials, the substrate temperature, the rate of deposition, the background pressure etc. Specific application in modern technology demand tailor made film properties, for example, high optical reflection / transmission, hardness. adhesion, nonporosity, high mobility of charge carriers / insulating properties and chemical inertness, which are possible with a selection of suitable functional materials and deposition techniques. Various techniques used to deposit thin films and the material properties of MIO and its crystal structure are summarized with our results.
Synthesis of Lanthanum Nickelate and Praseodymium Substituted Compounds by Molten Salt Technique
Authors: Arockiam S. Ignatius , Berchmans L. John , Angappan S. , Visuvasam A. , Mani V.
Published: September 2011

Lanthanum Nickelate (LaNiO3) and Praseodymium (Pr) substituted compounds were prepared by molten flux method using chloride precursors. The investigation presents the characterization of the synthesized materials using TGA/DTA, XRD, FTIR, CHNS, EDAX, UV-visible, EPR spectral and SEM studies. The thermo gravimetric analysis reveals the decomposition and thermal reactions of the precursors at different temperature regions. The XRD analysis shows that the synthesized crystals have the rhombohedral structure. FTIR spectra exhibit the absorption bands for the O-H stretching vibration and Ni-O bands at different wave lengths. A shift in band position has been observed on the substitution of Pr3+ions in the parent compound. The CHNS analysis presents the impurities level in the synthesized compounds. The EDAX analysis shows the concentration of La, Ni, Pr and O in the synthesized compounds. The band gap of the material has been determined from UV spectra and it is found to be 4.96 eV for the parent compound. The lone pair of electron state is identified from the EPR spectra. The SEM micrographs have shown the presence of fine crystallites with irregular morphology. The average particle size of the powders is ranging between 25-35 μm. From the above studies, it has been concluded that pure crystals of LaNiO3and Praseodymium substituted compounds can be conveniently synthesized by molten salt technique.
Synthesis and Characterization of the Nano Semiconducting Material Cadmium Sulphide
Authors: Jacob S. Santhosh Kumar , S. Saravananakumar , Saravanan R.
Published: September 2011

In this work, CdS nano particles were synthesized using aqueous precipitation method; This method is simple, fast and can be carried out at room temperature. Various techniques like X-ray powder diffraction and UV-visible absorption spectroscopy are used for the structural characterization like electron density distribution and estimation of inter atomic distances between the atoms of the nano particles. The optical band gap of this material has been determined in order to establish a relationship between energy gap of bulk and nano materials.
Low Frequency Raman Modes of Bi2 −x PbxSr1.6Ln0.4CuO6 −δ
Authors: Mallett Benjamin P. P. , Schnyder Thierry , Williams Grant V. M. , Tallon Jeffery L.
Published: September 2011

Raman measurements were made on polycrystalline Bi2xPbxSr1:6Ln0:4CuO6 for Ln=fLa,Nd, Sm, Eug with various x and doping states. Our measurements suggest a signi cant Bicontribution to the 118cm1 mode but not to the 70cm1 mode which instead shifts to lowerfrequencies with increasing number of CuO2 layers in the Bi-based family. Shifts in the O(2)Srapical oxygen mode can be attributed to unit cell contraction within experimental error.
Hybrid Nanocomposite of CdSe Quantum Dots and a P3HT-b-PDMAEMA Block Copolymer for Photovoltaic Applications
Authors: Kim Sung Won , Kim Dongh Wan , Kim Hyun Ji , Lee Yun Jae , Wang Seung Sangh , Baek Kyung Youl
Published: September 2011

We synthesized a new hybrid nanocomposite consisting of CdSe quantum dot (QD) and regioregular poly (3-hexylthiophene)-b-poly (N,N-dimethylamino-2-ethylmethacrylate) rod-coil block copolymer to investigate the effects of nanoscale morphology to the photovoltaic properties in inorganic-organic hybrid solar cell. Well-defined conducting rod-coil block copolymers, P3HT-b-PDMAEMA, were synthesized by combination of Grignard metathesis polymerization (GRIM) and atom transfer radical polymerization (ATRP) methods. These rod-coil block copolymers were then mixed with oleic acid capped CdSe QDs through ligand exchange and characterized their nanoscale morphology and optoelectronic properties. These results can be explained by the effects of the bicontinuous electron-donor/electron-acceptor networks in active layer based on rod-coil P3HT-b-PDMAEMA block copolymers blended with CdSe QDs.
Formation of Nanoparticles in Zr and Dy Doped YBCO MOD Superconducting Films
Authors: Xia James A. , Strickland Nick M. , Talantsev Evgueni F. , Long Nick J.
Published: September 2011

We study the formation mechanism of nanoparticles in thin films of the superconductor YBa2Cu3O7-δ(YBCO). We form the films by metal-organic deposition (MOD) on buffered, textured metal substrates. Through the addition of Dy or Zr salts to the precursor solution we precipitate (Y,Dy)2O3and BaZrO3nanoparticles, uniformly distributed through the film thickness. By quenching samples during the film growth, we show the nanoparticles form in the precursor layer before YBCO growth. The size of the nanoparticles was quantitatively analysed by TEM. We found that Zr doping produces smaller nanoparticles than Dy doping.
Characterization of Pd Nano-Thin Films for High-Speed Switchable Mirrors
Authors: Poh Chung Kiak , Poh Chung How , Guo Zai Ping , Liu Hua Kun
Published: September 2011

We fabricated Pd thin films from 2 to 35 nm thick via thermal evaporation, and a hermetically sealed hydrogen optical cell was used to characterize the films for properties such as hydrogen fractional ratio, optical switching contrast (Weber contrast), and response and recovery times. An atomic force microscope with a high resolution scanning tip was used to study the evolution of the film morphology.
Effect of Morphology of Conducting Polymer on DNA Sensing
Authors: Kannan Bhuvaneswari , Williams David E. , Travas-Sejdic Jadranka
Published: September 2011

Electrochemical DNA sensors can be constructed by understanding basic interfacial electron transfer between solid surface-electrolyte-DNA interfaces. The kinetics of this heterogeneous process can be significantly affected by the microstructure and roughness of the electrode surface. By understanding this concept, in this paper; we compared the performance of micro electrodes containing poly(Py-co-PAA) with macro electrode containing same copolymer, showing that micro electrodes are more sensitive than the macro electrodes for biosensor applications. Sensors based on the copolymer electropolymerised on both micro and macro electrodes were evaluated across a range of oligonucleotide concentrations. The interfacial electron charge transfer resistance between the solution and electrode surface was studied using electrochemical impedance spectroscopy (EIS).
Electronic Chemical Properties of Vanadium Doped TiO2 for Photocatalytic Degradation of BTEX
Authors: Laokiat Laksana , Khemthong Pongtanawat , Grisdanurak Nurak
Published: September 2011

V-doped TiO2(V-TiO2) was synthesised using solvothermal technique and immobilised onto fibreglass cloth (FGC). The XRD pattern of doped sample showed slight positive shift to higher angle indicating that the V ions were well substituted into the Ti lattices. The band-gap energy of V-TiO2was lower than that of P25, pure TiO2, (3.28 eV for P25 and 2.90 eV for V-TiO2) demonstrating it could be excited by visible light. The XANES spectra of the Ti K-edge transition indicated most Ti ions were in the tetravalent state with octahedral coordination. The A2species on the surfaces of V-TiO2were found to be the main active sites during photocatalytic degradation of BTEX under visible light irradiation.
Samarium Doped KMgF3 Nanoparticles
Authors: Janssens Stefaan , Williams Grant V. M. , Clarke David
Published: September 2011

In this paper we report the results from characterization and optical measurements on samarium doped KMgF3 nanoparticles. Photoluminescence (PL) is observed that can be attributed to Sm2+ and Sm3+. The Sm2+ temperature dependent PL lifetime data can be interpreted in terms of back transfer from the 5D0 level to the lowest 5d level followed by non-radiative decay from the 5d level.
Pinning Force Anisotropy for HTS Wires
Authors: Talantsev Evgueni F. , Long Nicholas J. , Strickland Nicholas M. , Tallon Jeffery L.
Published: September 2011

We investigate the pinning force anisotropy for BSCCO and YBCO commercial wires at 77 K. The pinning force is measured to 3 T and for all field angles. We show that the magnitude of the pinning force maximum as a function of applied field angle follows known statistical functions. The position of the maximum with field also follows these functions. This is a step towards a Dew-Hughes type scaling covering field, field angle and temperature for HTS wire.
Effect of Valence-Band Mixing on Density Oscillations in 2D Hole Systems
Authors: Kernreiter Thomas , Governale Michele , Zülicke Ulrich
Published: September 2011

We have calculated the spatial profile of density modulations generated in two-dimensional (2D) hole gases in response to an impurity potential. Both short-range and Coulombic point impurities are considered. The density response of hole systems turns out to be generally different from that seen in conduction-electron systems. Our results point to the importance of valence-band-mixing effects, especially in the regime of higher hole sheet densities.
Forced Nano-Oscillators Comprising Double-Walled Nanotubes
Authors: Cox Barry J.
Published: September 2011

We examine a class of nano-oscillator comprising an outer carbon nanotube that isuncapped and xed, within which oscillates an inner nanotube. The inner tube is acted on byexcess van der Waals forces as well as an applied sinusoidal force, which may result from a timevarying external electric eld acting on ions functionalised to the inner nanotube. Although theequations of motion contain both a non-linear position dependence as well as a time-varyingterm; by neglecting dissipative terms and considering the solution in di erent spatial domains,we reduce the problem to one with an analytical solution which we then evolve in time, solvingfor the domain boundaries to generate a full numerical solution.We nd a frequency dependenceon the maximum extrusion distance which is suggestive that the system may be used as the basisfor an accurate frequency detection device with sensitivity in the gigahertz range. We also notethat for a xed frequency of forcing, variations in the electric eld strength lead to changesin the amplitude and frequency of the response of the oscillator. Finally, we also commentthat an analysis of the position-momentum space reveals that in general the system occupiesall combinations of position and momentum inside a total energy envelop. However, carefullychosen initial conditions may lead to highly deterministic paths, where small perturbations tothese initial condtions quickly lead to a loss of order and thus we conclude these systems exhibitchaotic behaviour in these cases.
The SLP-76 Src Homology 2 Domain Is Required for T Cell Development and Activation
Authors: Burns Jeremy C. , Corbo Evann , Degen Janine , Gohil Mercy , Anterasian Christine , Schraven Burkart , Koretzky Gary A. , Kliche Stefanie , Jordan Martha S.
Published: September 2011

The adapter protein Src homology 2 (SH2) domain-containing leukocyte protein of 76 kDa (SLP-76) is critical for multiple aspects of T cell development and function. Through its protein-binding domains, SLP-76 serves as a platform for the assembly of multiple enzymes and adapter proteins that function together to activate second messengers required for TCR signal propagation. The N terminus of SLP-76, which contains three tyrosines that serve as docking sites for SH2 domain-containing proteins, and the central proline-rich region of SLP-76 have been well studied and are known to be important for both thymocyte selection and activation of peripheral T cells. Less is known about the function of the C-terminal SH2 domain of SLP-76. This region inducibly associates with ADAP and HPK1. Combining regulated deletion of endogenous SLP-76 with transgenic expression of a SLP-76 SH2 domain mutant, we demonstrate that the SLP-76 SH2 domain is required for peripheral T cell activation and positive selection of thymocytes, a function not previously attributed to this region. This domain is also important for T cell proliferation, IL-2 production, and phosphorylation of protein kinase D and IκB. ADAP-deficient T cells display similar, but in some cases less severe, defects despite phosphorylation of a negative regulatory site on SLP-76 by HPK1, a function that is lost in SLP-76 SH2 domain mutant T cells.
Sensitivity and Resistance to Regulation by IL-4 during Th17 Maturation
Authors: Cooney Laura A. , Towery Keara , Endres Judith , Fox David A.
Published: September 2011

Th17 cells are highly pathogenic in a variety of immune-mediated diseases, and a thorough understanding of the mechanisms of cytokine-mediated suppression of Th17 cells has great therapeutic potential. In this article, we characterize the regulation of both in vitro- and in vivo-derived Th17 cells by IL-4. We demonstrate that IL-4 suppresses reactivation of committed Th17 cells, even in the presence of TGF-β, IL-6, and IL-23. Downregulation of IL-17 by IL-4 is dependent on STAT6 and mediated by inhibition of STAT3 binding at the Il17a promoter. Although Th1 cytokines were shown to induce IFN-γ expression by Th17 cells, IL-4 does not induce a Th2 phenotype in Th17 cells. Suppression by IL-4 is stable and long-lived when applied to immature Th17 cells, but cells that have undergone multiple rounds of stimulation, either in vivo during a Th17-mediated inflammatory disease, or in vitro, become resistant to suppression by IL-4 and lose the ability to signal through IL-4R. Thus, although IL-4 is a potent suppressor of the Th17 genetic program at early stages after differentiation, prolonged stimulation renders Th17 cells impervious to regulatory cytokines.
Role of IL-17A in Neutrophil Recruitment and Hepatic Injury after Warm Ischemia–Reperfusion Mice
Authors: Kono Hiroshi , Fujii Hideki , Ogiku Masahito , Hosomura Naohiro , Amemiya Hidetake , Tsuchiya Masato , Hara Michio
Published: September 2011

Recent evidence suggests that IL-17A regulates neutrophil-dependent organ injury. Accordingly, the purpose of this study was to determine the role of IL-17A in neutrophil recruitment after ischemia–reperfusion (I/R) and in subsequent liver injury. Two mouse models including wild-type and IL-17A knockout mice were evaluated for I/R injury. The medial largest lobe of the liver was clamped for 90 min. In another set of experiments, recombinant mouse (rm)IL-17A homodimer or rmIL-17A/F heterodimer were administered to knockout mice before I/R, and liver injury was investigated. Isolated Kupffer cells were incubated with rmIL-17A or rmIL-17F, and production of TNF-α was measured. Studies evaluating the extent of liver injury as measured by serum transaminase levels demonstrated similar levels in the acute phase (6 h) in these two models. In contrast, in the subacute phase (20 h) after I/R, both serum transaminase levels and percent of hepatic necrosis were significantly reduced in the knockout mice compared with the wild-type mice. This reduction in liver injury seen in the knockout mice was associated with suppression of chemokine and adhesion molecule expression and reduction in infiltration of neutrophils into the liver. Administration of rmIL-17A homodimer, but not IL-17A/F heterodimer, increased liver injury in the subacute phase of I/R in KO mice. TNF-α production by isolated Kupffer cells increased significantly in the cells incubated with rmIL-17A compared with rmIL-17F. These results indicate that IL-17A is a key regulator in initiating neutrophil-induced inflammatory responses and hepatic injury in the subacute phase after reperfusion.
Cutting Edge: Regulatory T Cells Do Not Mediate Suppression via Programmed Cell Death Pathways
Authors: Szymczak-Workman Andrea L. , Delgoffe Greg M. , Green Douglas R. , Vignali Dario A. A.
Published: September 2011

Regulatory T cells (Tregs) play a critical role in the immune system to regulate peripheral tolerance and prevent autoimmunity. However, the relative importance of different mechanisms of Treg function remains obscure. In this article, we reveal a limited role for programmed cell death pathways in mediating Treg suppression of conventional T cells. We show that Tregs are able to suppress the proliferation of conventional T cells that are resistant to apoptosis (Bim−/−, Bim−/−Puma−/−, Bcl-2 transgenic) or receptor-interacting serine-threonine kinase-dependent necrosis (also referred to as regulated necrosis or necroptosis) (Ripk3−/−) in several in vitro and in vivo assays. These data suggest that programmed cell death pathways, such as apoptosis and receptor-interacting serine-threonine kinase-dependent necrosis, are not required for Treg-mediated suppression.
Cutting Edge: IRF8 Regulates Bax Transcription In Vivo in Primary Myeloid Cells
Authors: Yang Jine , Hu Xiaolin , Zimmerman Mary , Torres Christina M. , Yang Dafeng , Smith Sylvia B. , Liu Kebin
Published: September 2011

A prominent phenotype of IRF8 knockout (KO) mice is the uncontrolled expansion of immature myeloid cells. The molecular mechanism underlying this myeloproliferative syndrome is still elusive. In this study, we observed that Bax expression level is low in bone marrow preginitor cells and increases dramatically in primary myeloid cells in wt mice. In contrast, Bax expression level remained at a low level in primarymyeloid cells in IRF8 KO mice. However, in vitro IRF8 KO bone marrow-differentiated myeloid cells expressed Bax at a level as high as that in wild type myeloid cells. Furthermore, we demonstrated that IRF8 specifically binds to the Bax promoter region in primary myeloid cells. Functional analysis indicated that IRF8 deficiency results in increased resistance of the primary myeloid cells to Fas-mediated apoptosis. Our findings show that IRF8 directly regulates Bax transcription in vivo, but not in vitro during myeloid cell lineage differentiation.
Cutting Edge: CD40–CD40 Ligand Pathway Plays a Critical CD8-Intrinsic and -Extrinsic Role during Rescue of Exhausted CD8 T Cells
Authors: Bhadra Rajarshi , Gigley Jason P. , Khan Imtiaz A.
Published: September 2011

CD8 exhaustion mediated by an inhibitory programmed death-1–programmed death ligand-1 (PD-L1) pathway occurs in several chronic infections, including toxoplasmosis. Although blockade of the programmed death-1–PD-L1 pathway revives this response, the role of costimulatory receptors involved in this rescue has not been ascertained in any model of CD8 exhaustion. This report demonstrates that one such costimulatory pathway, CD40–CD40L, plays a critical role during rescue of exhausted CD8 T cells. Blockade of this pathway abrogates the ameliorative effects of anti–PD-L1 treatment on CD8 T cells. Additionally, we demonstrate in an infectious disease model that CD8-intrinsic CD40 signaling is important for optimal CD8 polyfunctionality, proliferation, T-bet upregulation, and IL-21 signaling, albeit in the context of CD8 rescue. The critical role of CD40 during the rescue of exhausted CD8 T cells may provide a rational basis for designing novel therapeutic vaccination approaches.
Do Stress Trajectories Predict Mortality in Older Men? Longitudinal Findings from the VA Normative Aging Study
Authors: Aldwin Carolyn M. , Molitor Nuoo-Ting , Spiro Avron , Levenson Michael R. , Molitor John , Igarashi Heidi
Published: September 2011

We examined long-term patterns of stressful life events (SLE) and their impact on mortality contrasting two theoretical models: allostatic load (linear relationship) and hormesis (inverted U relationship) in 1443 NAS men (aged 41–87 in 1985;M= 60.30, SD = 7.3) with at least two reports of SLEs over 18 years (total observations = 7,634). Using a zero-inflated Poisson growth mixture model, we identified four patterns of SLE trajectories, three showing linear decreases over time with low, medium, and high intercepts, respectively, and one an inverted U, peaking at age 70. Repeating the analysis omitting two health-related SLEs yielded only the first three linear patterns. Compared to the low-stress group, both the moderate and the high-stress groups showed excess mortality, controlling for demographics and health behavior habits, HRs = 1.42 and 1.37,ps<.01and<.05. The relationship between stress trajectories and mortality was complex and not easily explained by either theoretical model.
Ice nucleation properties of volcanic ash from Eyjafjallajökull
Authors: Hoyle C. R. , Pinti V. , Welti A. , Zobrist B. , Marcolli C. , Luo B. , Höskuldsson Á. , Mattsson H. B. , Stetzer O. , Thorsteinsson T. , Larsen G. , Peter T.
Published: September 2011

Abstract. The ice nucleation ability of volcanic ash particles collected close to the Icelandic volcano Eyjafjallajökull during its eruptions in April and May 2010 is investigated experimentally, in the immersion and deposition modes, and applied to atmospheric conditions by comparison with airborne measurements and microphysical model calculations. The number of ash particles which are active as ice nuclei (IN) is strongly temperature dependent, with a very small minority being active in the immersion mode at temperatures of 250–263 K. Average ash particles show only a moderate effect on ice nucleation, by inducing freezing at temperatures between 236 K and 240 K (i.e. approximately 3–4 K higher than temperatures required for homogeneous ice nucleation, measured with the same instrument). By scaling the results to aircraft and lidar measurements of the conditions in the ash plume days down wind of the eruption, and by applying a simple microphysical model, it was found that the IN active in the immersion mode in the range 250–263 K generally occurred in atmospheric number densities at the lower end of those required to have an impact on ice cloud formation. However, 3–4 K above the homogeneous freezing point, immersion mode IN number densities a few days down wind of the eruption were sufficiently high to have a moderate influence on ice cloud formation. The efficiency of IN in the deposition mode was found to be poor except at very cold conditions (<238 K), when they reach an efficiency similar to that of mineral dust with the onset of freezing at 10 % supersaturation with respect to ice, and with the frozen fraction nearing its maximum value at a supersaturation 20 %. In summary, these investigations suggest volcanic ash particles to have only moderate effects on atmospheric ice formation.
Ethane, ethyne and carbon monoxide concentrations in the upper troposphere and lower stratosphere from ACE and GEOS-Chem: a comparison study
Authors: González Abad G. , Allen N. D. C. , Bernath P. F. , Boone C. D. , McLeod S. D. , Manney G. L. , Toon G. C. , Carouge C. , Wang Y. , Wu S. , Barkley M. P. , Palmer P. I. , Xiao Y. , Fu T. M.
Published: September 2011

Abstract. Near global upper tropospheric concentrations of carbon monoxide (CO), ethane (C2H6) and ethyne (C2H2) from ACE (Atmospheric Chemistry Experiment) Fourier transform spectrometer on board the Canadian satellite SCISAT-1 are presented and compared with the output from the Chemical Transport Model (CTM) GEOS-Chem. The retrievals of ethane and ethyne from ACE have been improved for this paper by using new sets of microwindows compared with those for previous versions of ACE data. With the improved ethyne retrieval we have been able to produce a near global upper tropospheric distribution of C2H2 from space. Carbon monoxide, ethane and ethyne concentrations retrieved using ACE spectra show the expected seasonality linked to variations in the anthropogenic emissions and destruction rates as well as seasonal biomass burning activity. The GEOS-Chem model was run using the dicarbonyl chemistry suite, an extended chemical mechanism in which ethyne is treated explicitly. Seasonal cycles observed from satellite data are well reproduced by the model output, however the simulated CO concentrations are found to be systematically biased low over the Northern Hemisphere. An average negative global mean bias of 12% and 7% of the model relative to the satellite observations has been found for CO and C2H6 respectively and a positive global mean bias of 1% has been found for C2H2. ACE data are compared for validation purposes with MkIV spectrometer data and Global Tropospheric Experiment (GTE) TRACE-A campaign data showing good agreement with all of them.
Global precipitation response to changing forcings since 1870
Authors: Bichet A. , Wild M. , Folini D. , Schär C.
Published: September 2011

Abstract. Predicting and adapting to changes in the hydrological cycle is one of the major challenges for the 21st century. To better estimate how it will respond to future changes in climate forcings, it is crucial to understand how the hydrological cycle has evolved in the past and why. In our study, we use an atmospheric global climate model with prescribed sea surface temperatures (SSTs) to investigate how, in the period 1870–2005, changing climate forcings have affected the global land temperature and precipitation. We show that between 1870 and 2005, prescribed SSTs (encapsulating other forcings and internal variability) determine the decadal and interannual variabilities of the global land temperature and precipitation, mostly via their influence in the tropics (25° S–25° N). In addition, using simulations with prescribed SSTs and considering the atmospheric response alone, we find that between 1930 and 2005 increasing aerosol emissions have reduced the global land temperature and precipitation by up to 0.4 °C and 30 mm yr−1, respectively, and that between about 1950 and 2005 increasing greenhouse gas concentrations have increased them by up to 0.25 °C and 10 mm yr−1, respectively. Finally, we suggest that between about 1950 and 1970, increasing aerosol emissions had a larger impact on the hydrological cycle than increasing greenhouse gas concentrations.
Summertime impacts of Eastern Mediterranean megacity emissions on air quality
Authors: Im U. , Kanakidou M.
Published: September 2011

Abstract. Megacities are large urban agglomerations with intensive anthropogenic emissions that have significant impacts on local and regional air quality. In the present mesoscale modeling study, the impacts of anthropogenic emissions from Istanbul and Athens on local and regional air quality in the Eastern Mediterranean are quantified and the responses to hypothetical decentralization scenarios applied to the extended areas of these densely populated regions are evaluated. This study focuses on summertime impacts on air quality. The results show that Athens emissions have larger regional (0.8%) and downwind (2.7% at Finokalia) impacts on O3 than Istanbul emissions that contribute to surface O3 by 0.6% to the domain-mean and 2.1% to the levels at Finokalia. On the opposite, regarding fine particle (PM2.5) levels, Istanbul emissions have larger contribution both inside the megacity itself (75%) and regionally (2.4%) compared to Athens emissions, which have a local contribution of 65% and domain-wide contribution of 0.4%. Biogenic emissions are found to limit the production of secondary inorganic aerosol species due to their impact on oxidant levels. Hypothetical decentralization plans for these urban agglomerations, maintaining the total amount of their anthropogenic emissions constant but homogeneously distributing it over larger "new" extended areas, would result in higher O3 mixing ratios inside the urban core (215% and 26% in Istanbul and Athens, respectively). On the opposite, PM2.5 concentrations would decrease by 67% and 60% in Istanbul and Athens, respectively, whereas they would increase by 10% and 11% in the rural areas of Istanbul and Athens, respectively. Concerning the "new" extended areas, Athens would experience a reduction in O3 mixing ratios by ~2% whereas Istanbul would experience an increase by ~15%. Overall decreases of PM2.5 levels by 32% and 9% are calculated over the Istanbul and Athens "new" extended areas.
The ACOS CO2 retrieval algorithm – Part 1: Description and validation against synthetic observations
Authors: O'Dell C. W. , Connor B. , Bösch H. , O'Brien D. , Frankenberg C. , Castano R. , Christi M. , Crisp D. , Eldering A. , Fisher B. , Gunson M. , McDuffie J. , Miller C. E. , Natraj V. , Oyafuso F. , Polonsky I. , Smyth M. , Taylor T. , Toon G. C. , Wennberg P. O. , Wunch D.
Published: September 2011

Abstract. This work describes the NASA Atmospheric CO2 Observations from Space (ACOS) XCO2 retrieval algorithm, and its performance on highly realistic, simulated observations. These tests, restricted to observations over land, are used to evaluate retrieval errors in the face of realistic clouds and aerosols, polarized non-Lambertian surfaces, imperfect meteorology, and uncorrelated instrument noise. We find that post-retrieval filters are essential to eliminate the poorest retrievals, which arise primarily due to imperfect cloud screening. The remaining retrievals have RMS errors of approximately 1 ppm. Modeled instrument noise, based on the Greenhouse Gases Observing SATellite (GOSAT) in-flight performance, accounts for less than half the total error in these retrievals. A small fraction of unfiltered clouds, particularly thin cirrus, lead to a small positive bias of ~0.3 ppm. Overall, systematic errors due to imperfect characterization of clouds and aerosols dominate the error budget, while errors due to imperfect meteorology, surface reflectance, and radiative transfer assumptions are small.
Gas properties of winter lake ice in Northern Sweden: biogeochemical processes and implication for carbon gas release
Authors: Boereboom T. , Depoorter M. , Coppens S. , Tison J.-L.
Published: September 2011

Abstract. This paper describes gas composition, total gas content and bubbles characteristics in winter lake ice for four adjacent lakes in a discontinuous permafrost area. Our gas mixing ratios suggest that gas exchange occurs between the bubbles and the water before entrapment in the ice. Comparison between lakes enabled us to identify 2 major "bubbling events" shown to be related to a regional drop of atmospheric pressure. Further comparison demonstrates that winter lake gas content is strongly dependent on hydrological connections: according to their closed/open status with regards to water exchange, lakes build up more or less greenhouse gases (GHG) in their water and ice cover during the winter, and release it during spring melt. These discrepancies between lakes need to be taken into account when establishing a budget for permafrost regions. Our analysis allows us to present a new classification of bubbles, according to their gas properties. Our methane emission budget (from 6.52 10−5 to 12.7 mg CH4 m−2 d−1) for the three months of winter ice cover is complementary to the other budget estimates, taking into account the variability of the gas distribution in the ice and between the various types of lakes. Most available studies on boreal lakes have focused on quantifying GHG emissions from sediment by means of various systems collecting gases at the lake surface, and this mainly during the summer "open water" period. Only few of these have looked at the gas enclosed in the winter ice-cover itself. Our approach enables us to integrate, for the first time, the history of winter gas emission for this type of lakes.
A Lagrangian model of air-mass photochemistry and mixing using a trajectory ensemble: the Cambridge Tropospheric Trajectory model of Chemistry And Transport (CiTTyCAT) version 4.2
Authors: Pugh T. A. M. , Cain M. , Methven J. , Wild O. , Arnold S. R. , Real E. , Law K. S. , Emmerson K. M. , Owen S. M. , Pyle J. A . , Hewitt C. N. , MacKenzie A. R.
Published: September 2011

Abstract. A Lagrangian model of photochemistry and mixing is described (CiTTyCAT, stemming from the Cambridge Tropospheric Trajectory model of Chemistry And Transport), which is suitable for transport and chemistry studies throughout the troposphere. Over the last five years, the model has been developed in parallel at several different institutions and here those developments have been incorporated into one "community" model and documented for the first time. The key photochemical developments include a new scheme for biogenic volatile organic compounds and updated emissions schemes. The key physical development is to evolve composition following an ensemble of trajectories within neighbouring air-masses, including a simple scheme for mixing between them via an evolving "background profile", both within the boundary layer and free troposphere. The model runs along trajectories pre-calculated using winds and temperature from meteorological analyses. In addition, boundary layer height and precipitation rates, output from the analysis model, are interpolated to trajectory points and used as inputs to the mixing and wet deposition schemes. The model is most suitable in regimes when the effects of small-scale turbulent mixing are slow relative to advection by the resolved winds so that coherent air-masses form with distinct composition and strong gradients between them. Such air-masses can persist for many days while stretching, folding and thinning. Lagrangian models offer a useful framework for picking apart the processes of air-mass evolution over inter-continental distances, without being hindered by the numerical diffusion inherent to global Eulerian models. The model, including different box and trajectory modes, is described and some output for each of the modes is presented for evaluation. The model is available for download from a Subversion-controlled repository by contacting the corresponding authors.
A simple water-energy balance framework to predict the sensitivity of streamflow to climate change
Authors: Renner M. , Seppelt R. , Bernhofer C.
Published: September 2011

Abstract. Long term average change in streamflow is a major concern in hydrology and water resources management. Some simple analytical methods exist for the assessment of the sensitivity of streamflow to climatic variations. These are based on the Budyko hypothesis, which assumes that long term average streamflow can be predicted by climate conditions, namely by annual average precipitation and evaporative demand. Recently, Tomer and Schilling (2009) presented an ecohydrological concept to distinguish between effects of climate change and basin characteristics change on streamflow. We provide a theoretical foundation of this concept by showing that it is based on a coupled consideration of the water and energy balance. The concept uses a special condition that the sum of the ratio of annual actual evapotranspiration to precipitation and the ratio of actual to potential evapotranspiration is constant, even when climate conditions are changing. Here we apply this assumption and derive analytical solutions to the problem of streamflow sensitivity on climate. We show how climate sensitivity is influenced by different climatic conditions and the actual hydrological response of a basin. Finally, the properties and implications of the new method are compared with established Budyko sensitivity methods.
Rockfall characterisation and structural protection – a review
Authors: Volkwein A. , Schellenberg K. , Labiouse V. , Agliardi F. , Berger F. , Bourrier F. , Dorren L. K. A. , Gerber W. , Jaboyedoff M.
Published: September 2011

Abstract. Rockfall is an extremely rapid process involving long travel distances. Due to these features, when an event occurs, the ability to take evasive action is practically zero and, thus, the risk of injury or loss of life is high. Damage to buildings and infrastructure is quite likely. In many cases, therefore, suitable protection measures are necessary. This contribution provides an overview of previous and current research on the main topics related to rockfall. It covers the onset of rockfall and runout modelling approaches, as well as hazard zoning and protection measures. It is the aim of this article to provide an in-depth knowledge base for researchers and practitioners involved in projects dealing with the rockfall protection of infrastructures, who may work in the fields of civil or environmental engineering, risk and safety, the earth and natural sciences.
Monitoring spatial and temporal variations of surface albedo on Saint Sorlin Glacier (French Alps) using terrestrial photography
Authors: Dumont M. , Sirguey P. , Arnaud Y. , Six D.
Published: September 2011

Abstract. Accurate knowledge of temperate glacier mass balance is essential to understand the relationship between glacier and climate. Defined as the reflected fraction of incident radiation over the whole solar spectrum, the surface broadband albedo is one of the most important variable in a glacier's mass balance. This study presents a new method to retrieve the albedo of frozen surfaces from terrestrial photography at visible and near infrared wavelengths. This method accounts for the anisotropic reflectance of snow and ice surfaces and uses a radiative transfer model for narrow-to-broadband conversion. The accuracy of the method was assessed using concomitant measurements of albedo during the summers 2008 and 2009 on Saint Sorlin Glacier (Grandes Rousses, France). These albedo measurements are performed at two locations on the glacier, one in the ablation area and the other in the accumulation zone, with a net radiometer Kipp and Zonen CNR1. The main sources of uncertainty are associated with the presence of high clouds and the georeferencing of the photographs.
Ill convergence of minimum output energy infinite impulse response equalizer for digital vestigial sideband signals
Authors: Chung Wonzoo
Published: September 2011

Minimum output energy (MOE) algorithm is a widely used adaptive algorithm for blind adaptation of infinite impulse response (IIR) filters. In this paper, we show that the MOE algorithm is not suitable for blind adaptation of the complex‐valued IIR equalizer for digital vestigial sideband signals, whereas the constant modulus algorithm successfully achieves blind adaptation of the IIR equalizers when MOE fails. Because of the difficulty in analyzing IIR equalizers, the analysis is limited to a simple two‐tap channel case. For more general multitap channel cases, the performance of a complex constant modulus algorithm IIR is evaluated through simulation. Copyright © 2011 John Wiley & Sons, Ltd.
Oxidative Carbonylierungen: Organometallverbindungen (RM) oder Kohlenwasserstoffe (RH) als Nucleophile
Authors: Liu Qiang , Zhang Hua , Lei Aiwen
Published: September 2011

Oxidative Carbonylierungen haben in den letzten Jahren ein breites Interesse geweckt, und insbesondere die Synthese von Carbonat‐ und Harnstoffderivaten durch oxidative Carbonylierung von Alkoholen und Aminen wurde intensiv untersucht. Eine neuartige Entwicklung ist die direkte Verwendung von Organometallverbindungen (RM) und Kohlenwasserstoffen (RH) als Nucleophile zum Aufbau einer C‐C‐Bindung in oxidativen Carbonylierungen. Dieser Kurzaufsatz stellt diese neue Art der oxidativen Carbonylierung vor.
Structural properties of DNA oligomers containing (GACX)n and (GAXC)n tandem repeats
Authors: Dasgupta Indrani , Gao Xiaolian , Fox George E.
Published: September 2011

The antisense DNA sequence of mature mouse micro RNA, miR341, includes three repeats of the tetranucleotide (GACC). The ‐GAC‐ repeat is known to form a parallel duplex, in acidic environments. The thermal melting profile of miR341 DNA, at pH 4, 5, and 6 indicates the formation of a very stable structure, which loses its stability when pH is increased. Thus, the addition of a cytosine at the 3′ end of the (GAC) motif preserves the molecule's potential to fold into an unusual structure at low pH. The effect of modifying the nucleotide composition of the GACC sequence on the secondary structures formed by oligomers containing seven tandem repeats of the altered motifs was examined here. UV melting profiles were determined, as a function of pH, for 28‐mers of the two series (GAXC)7 and (GACX)7 (X= A/C/T/G). The sequence (GACC)7 was found to be extremely sensitive to pH variations, with a stable structure formed at pH 5 (Tm ≥ 60°C). NMR spectroscopy established that the low pH structure is not B‐DNA. (GACA)7 and (GACT)7 also formed stable structures at low pH but the addition of guanine at the 3′end, as seen in the (GACG) series resulted in the loss of this property. Introducing a break in the 5′‐GAC‐3′ motif, explored in the (GAXC) series, also inhibits formation of stable structures under acidic conditions. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 155–164, 2012.