bluuebunny/crossref_metadata_2025 huggingface dataset:
Peripherer Leberabszess: Darstellung und Behandlung mit Hilfe des Ultraschallkontrastmittels SonoVue®
Authors: Grunder  , Baumann
Published: August 2006

Wir beschreiben eine Patientin mit einem peripheren, pyogenen Leberabszess. Durch den Einsatz des Ultraschallkontrastmittels SonoVue® gelingt eine verbesserte Charakterisierung von Leberabszessen und eine Punktion wird dadurch erleichtert. Die Anwendung von Ultraschallkontrastmittel öffnet neue Aspekte in der Diagnostik von Leberabszessen und trägt dazu bei, die diagnostische und therapeutische Sicherheit zu erhöhen.
Global, low‐latitude, vertical E × B drift velocities inferred from daytime magnetometer observations
Authors: Anderson David , Anghel Adela , Chau Jorge L. , Yumoto Kiyohumi
Published: August 2006

Navigation and communication, Department of Defense and civilian, customers rely on accurate, low‐latitude specification of ionospheric parameters, globally, that are not currently realistic on a day‐to‐day basis. This paper describes, demonstrates, and speculates about the data sets that are required inputs to the operational ionospheric models that will correct these deficiencies. In order to investigate quiet time, vertical E × B drift velocities at two different longitude sectors, magnetometer observations were obtained for the period between January 2001 and December 2004 from the magnetometers at Jicamarca (0.8°N dip latitude) and Piura (6.8°N dip latitude) in Peru and from Davao (1.4°S dip latitude) and Muntinlupa (6.3°N dip latitude) in the Philippine sector. We choose only geomagnetically “quiet” days, when the 3‐hourly Kp value never exceeds a value of 3 over the entire day, and when the daily Ap value is less than 10. These are “binned” into three seasons, December solstice, equinox, and June solstice periods. A neural network trained for the Peruvian sector was applied to each of the days in both the Peruvian and Philippine sectors, providing ΔH‐inferred vertical E × B drift velocities between 0700 and 1700 local time. For each season, the average E × B drift velocity curves are compared with the Fejer‐Scherliess, climatological E × B drift velocity curves in both the Peruvian and Philippine sectors. In the Peruvian sector, the comparisons are excellent, and in the Philippine sector they are very good. We demonstrate that realistic magnetometer‐inferred E × B drifts can be obtained in the Peruvian sector on a day‐to‐day basis and speculate that on the basis of the average, quiet day comparisons, realistic E × B drifts can be obtained on quiet days in the Philippine sector.
A new Bayesian recursive technique for parameter estimation
Authors: Kaheil Yasir H. , Gill M. Kashif , McKee Mac , Bastidas Luis
Published: August 2006

The performance of any model depends on how well its associated parameters are estimated. In the current application, a localized Bayesian recursive estimation (LOBARE) approach is devised for parameter estimation. The LOBARE methodology is an extension of the Bayesian recursive estimation (BARE) method. It is applied in this paper on two different types of models: an artificial intelligence (AI) model in the form of a support vector machine (SVM) application for forecasting soil moisture and a conceptual rainfall‐runoff (CRR) model represented by the Sacramento soil moisture accounting (SAC‐SMA) model. Support vector machines, based on statistical learning theory (SLT), represent the modeling task as a quadratic optimization problem and have already been used in various applications in hydrology. They require estimation of three parameters. SAC‐SMA is a very well known model that estimates runoff. It has a 13‐dimensional parameter space. In the LOBARE approach presented here, Bayesian inference is used in an iterative fashion to estimate the parameter space that will most likely enclose a best parameter set. This is done by narrowing the sampling space through updating the “parent” bounds based on their fitness. These bounds are actually the parameter sets that were selected by BARE runs on subspaces of the initial parameter space. The new approach results in faster convergence toward the optimal parameter set using minimum training/calibration data and fewer sets of parameter values. The efficacy of the localized methodology is also compared with the previously used BARE algorithm.
Vertical seismoelectric profiling in a borehole penetrating glaciofluvial sediments
Authors: Dupuis J. C. , Butler K. E.
Published: August 2006

Seismoelectric signals have been measured as a function of depth in a borehole penetrating glaciofluvial sands, silts, and glacial till using a broadband surface seismic source, and a downhole electrode array. Transient electric field pulses, with amplitudes of 1 to 4 μV/m accompanied the arrival of seismic P‐waves at the electrodes but no simultaneous interfacial signals were observed above the noise floor of approximately 0.2 μV/m. The co‐seismic effect was strongest in a sand and gravel layer where its amplitude is consistent with the predictions of a simplified theoretical model. Normalization of the amplitude logs by measurements of seismic particle velocity and electrical conductivity enhanced their sensitivity to changes in lithology and porosity. The results of this experiment suggest that co‐seismic seismoelectric effects show potential as a porosity/permeability logging tool in the borehole environment.
Through thick and thin: Marine and meteoric ice in a “Snowball Earth” climate
Authors: Goodman Jason C.
Published: August 2006

Marine ice cover in the frigid Neoproterozoic climate system tends to isolate the ocean: the thickness of this ice, and thus the degree of isolation, is an important unknown in geochemical and biological arguments regarding the fully‐glaciated “Snowball Earth” hypothesis. The Pollard and Kasting (2005) coupled atmosphere/ice model has been modified to track ice of marine and atmospheric origin separately, and model their different optical properties. In contrast to Pollard and Kasting's results, a tropical region of thin ice is not stable in this model: ice is hundreds of meters thick everywhere. The overall pattern of the hydrological cycle in a Snowball climate is also discussed.
A comparison of terrestrial water storage variations from GRACE with in situ measurements from Illinois
Authors: Swenson Sean , Yeh Pat J.‐F. , Wahr John , Famiglietti James
Published: August 2006

This study presents the first direct comparison of terrestrial water storage estimates from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to in situ hydrological observations. Monthly anomalies of total water storage derived from GRACE gravity fields are compared with combined soil moisture and groundwater measurements from a network of observing sites in Illinois. This comparison is achieved through the use of a recently developed filtering technique designed to selectively remove correlated errors in the GRACE spectral coefficients. Application of this filter significantly improves the spatial resolution of the GRACE water storage estimates, and produces a time series which agrees quite well (RMS difference = 20.3 mm) with the in situ measurements averaged over an area of ∼280,000 km2.
Novel genes encoding six kinds of three-finger toxins in Ophiophagus hannah (king cobra) and function characterization of two recombinant long-chain neurotoxins
Authors: Li Jing , Zhang Huayuan , Liu Jing , Xu Kangsen
Published: August 2006

Three-finger toxins are a family of low-molecular-mass toxins (<10 kDa) having very similar three-dimensional structures. In the present study, 19 novel cDNAs coding three-finger toxins were cloned from the venom gland of Ophiophagus hannah (king cobra). Alignment analysis showed that the putative peptides could be divided into six kinds of three-finger toxins: LNTXs (long-chain neurotoxins), short-chain neurotoxins, cardiotoxins (CTXs), weak neurotoxins, muscarinic toxins and a toxin with a free SH group. Furthermore, a phylogenetic tree was established on the basis of the toxin cDNAs and the previously reported similar nucleotide sequences from the same source venom. It indicated that three-finger-toxin genes in O. hannah diverged early in the course of evolution by long- and short-type pathways. Two LNTXs, namely rLNTX1 (recombinant LNTX1) and rLNTX3, were expressed and showed cytolytic activity in addition to their neurotoxic function. By comparing the functional residues, we offer some possible explanations for the differences in their neurotoxic function. Moreover, a plausible elucidation of the additonal cytolytic activity was achieved by hydropathy-profile analysis. This, to our knowledge, is the first observation that recombinant long chain α-neurotoxins have a CTX-like cytolytic activity.
Evidence for inactivation of cysteine proteases by reactive carbonyls via glycation of active site thiols
Authors: Zeng Jingmin , Dunlop Rachael A. , Rodgers Kenneth J. , Davies Michael J.
Published: August 2006

Hyperglycaemia, triose phosphate decomposition and oxidation reactions generate reactive aldehydes in vivo. These compounds react non-enzymatically with protein side chains and N-terminal amino groups to give adducts and cross-links, and hence modified proteins. Previous studies have shown that free or protein-bound carbonyls inactivate glyceraldehyde-3-phosphate dehydrogenase with concomitant loss of thiol groups [Morgan, Dean and Davies (2002) Arch. Biochem. Biophys. 403, 259–269]. It was therefore hypothesized that modification of lysosomal cysteine proteases (and the structurally related enzyme papain) by free and protein-bound carbonyls may modulate the activity of these components of the cellular proteolytic machinery responsible for the removal of modified proteins and thereby contribute to a decreased removal of modified proteins from cells. It is shown that MGX (methylglyoxal), GO (glyoxal) and glycolaldehyde, but not hydroxyacetone and glucose, inhibit catB (cathepsin B), catL (cathepsin L) and catS (cathepsin S) activity in macrophage cell lysates, in a concentration-dependent manner. Protein-bound carbonyls produced similar inhibition with both cell lysates and intact macrophage cells. Inhibition was also observed with papain, with this paralleled by loss of the active site cysteine residue and formation of the adduct species S-carboxymethylcysteine, from GO, in a concentration-dependent manner. Inhibition of autolysis of papain by MGX, along with cross-link formation, was detected by SDS/PAGE. Treatment of papain and catS with the dialdehyde o-phthalaldehyde resulted in enzyme inactivation and an intra-molecular active site cysteine–lysine cross-link. These results demonstrate that reactive aldehydes inhibit cysteine proteases by modification of the active site cysteine residue. This process may contribute to the accumulation of modified proteins in tissues of people with diabetes and age-related pathologies, including atherosclerosis, cataract and Alzheimer's disease.
A novel Δ9 acyl-lipid desaturase, DesC2, from cyanobacteria acts on fatty acids esterified to the sn−2 position of glycerolipids
Authors: Chintalapati Suresh , Prakash Jogadhenu Shyam Sunder , Gupta Pratima , Ohtani Shuji , Suzuki Iwane , Sakamoto Toshio , Murata Norio , Shivaji Sisinthy
Published: August 2006

Acyl-lipid desaturases are enzymes that convert a C–C single bond into a C=C double bond in fatty acids that are esterified to membrane-bound glycerolipids. Four types of acyl-lipid desaturase, namely DesA, DesB, DesC, and DesD, acting at the Δ12, Δ15, Δ9, and Δ6 positions of fatty acids respectively, have been characterized in cyanobacteria. These enzymes are specific for fatty acids bound to the sn−1 position of glycerolipids. In the present study, we have cloned two putative genes for a Δ9 desaturase, designated desC1 and desC2, from Nostoc species. The desC1 gene is highly similar to the desC gene that encodes a Δ9 desaturase that acts on C18 fatty acids at the sn−1 position. Homologues of desC2 are found in genomes of cyanobacterial species in which Δ9-desaturated fatty acids are esterified to the sn−2 position. Heterologous expression of the desC2 gene in Synechocystis sp. PCC 6803, in which a saturated fatty acid is found at the sn−2 position, revealed that DesC2 could desaturate this fatty acid at the sn−2 position. These results suggest that the desC2 gene is a novel gene for a Δ9 acyl-lipid desaturase that acts on fatty acids esterified to the sn-2 position of glycerolipids.
The tert-butylhydroquinone-mediated activation of the human thioredoxin gene reveals a novel promoter structure
Authors: Osborne Simone A. , Hawkes Hye-Jin Kim , Baldwin Ben L. , Alexander Kylie A. , Svingen Terje , Clarke Frank M. , Tonissen Kathryn F.
Published: August 2006

Thioredoxin is a redox-active protein that plays multiple roles in regulating cell growth, cell signalling and apoptosis. Here, we have demonstrated that a complex mechanism involving multiple regulatory elements is involved in the tBHQ [tert-butylhydroquinone or 2,5-di-(t-butyl)-1,4-hydroquinone]-mediated activation of the thioredoxin gene. Luciferase assays, utilizing various wild-type and mutated thioredoxin promoter fragments, revealed roles for the ORE (oxidative stress responsive element), ARE (antioxidant responsive element), three Sp1 (specificity protein 1)-binding sites and the TATA box in the activation of the thioredoxin gene by tBHQ. The ORE required the presence of the ARE to elicit its response, whereas the independent removal of three Sp1-binding sites and the TATA box also decreased activation of the thioredoxin gene, with mutation of the TATA box having the greatest effect. Real-time RT (reverse transcriptase)–PCR analysis also revealed varying roles for two TSSs (transcription start sites) in the activation of the thioredoxin gene by tBHQ. Transcription was initiated from both TSSs; however, different response rates and fold inductions were observed. Together, these results suggest that the thioredoxin gene is controlled by a novel arrangement of two overlapping core promoter regions, one containing a TATA box and the other TATA-less. Altering the intracellular levels of thioredoxin in a breast cancer cell line also influenced the induction of thioredoxin transcription in response to tBHQ. Stable transfections with a redox-inactive thioredoxin mutant produced 3.6 times higher induction levels of thioredoxin transcription compared with control cells, indicating an intrinsic form of control of promoter activity by the thioredoxin system itself.
Nucleotides bind to the C-terminus of ClC-5
Authors: Wellhauser Leigh , Kuo Hsin-Hen , Stratford Fiona L. L. , Ramjeesingh Mohabir , Huan Ling-Jun , Luong Winnie , Li Canhui , Deber Charles M. , Bear Christine E.
Published: August 2006

Mutations in ClC-5 (chloride channel 5), a member of the ClC family of chloride ion channels and antiporters, have been linked to Dent's disease, a renal disease associated with proteinuria. Several of the disease-causing mutations are premature stop mutations which lead to truncation of the C-terminus, pointing to the functional significance of this region. The C-terminus of ClC-5, like that of other eukaryotic ClC proteins, is cytoplasmic and contains a pair of CBS (cystathionine β-synthase) domains connected by an intervening sequence. The presence of CBS domains implies a regulatory role for nucleotide interaction based on studies of other unrelated proteins bearing these domains [Ignoul and Eggermont (2005) Am. J. Physiol. Cell Physiol. 289, C1369–C1378; Scott, Hawley, Green, Anis, Stewart, Scullion, Norman and Hardie (2004) J. Clin. Invest. 113, 274–284]. However, to date, there has been no direct biochemical or biophysical evidence to support nucleotide interaction with ClC-5. In the present study, we have expressed and purified milligram quantities of the isolated C-terminus of ClC-5 (CIC-5 Ct). CD studies show that the protein is compact, with predominantly α-helical structure. We determined, using radiolabelled ATP, that this nucleotide binds the folded protein with low affinity, in the millimolar range, and that this interaction can be competed with 1 μM AMP. CD studies show that binding of these nucleotides causes no significant change in secondary structure, consistent with a model wherein these nucleotides bind to a preformed site. However, both nucleotides induce an increase in thermal stability of ClC-5 Ct, supporting the suggestion that both nucleotides interact with and modify the biophysical properties of this protein.
Lopap, a prothrombin activator from Lonomia obliqua belonging to the lipocalin family: recombinant production, biochemical characterization and structure–function insights
Authors: Reis Cleyson Valença , Andrade Sonia Aparecida , Ramos Oscar Henrique Pereira , Ramos Celso Raul Romero , Ho Paulo Lee , Batista Isabel de Fátima Correia , Chudzinski-Tavassi Ana Marisa
Published: August 2006

Using a cDNA library made from Lonomia obliqua caterpillar bristles, we identified a transcript with a 603 bp open reading frame. The deduced protein corresponds to Lopap, a prothrombin activator previously isolated by our group from the bristles of this species. The mature protein is composed by 185 amino acids and shares similarity with members of the lipocalin family. The cDNA encoding the mature form was amplified by PCR, subcloned into pAE vector and used to transform Escherichia coli BL21(DE3) cells. As for the native Lopap, the recombinant fusion protein shows enzymatic activity, promotes prothrombin hydrolysis, generates fragments similar to prethrombin-2 and fragment 1.2 as intermediates, and generates thrombin as the final product. In addition, structural bioinformatics studies indicated several interesting molecular features, including the residues that could be responsible for Lopap's serine protease-like activity and the role of calcium binding in this context. Such catalytic activity has never been found in other members of the lipocalin family. This is the first report describing the recombinant production and biochemical characterization of a Lonomia obliqua lipocalin, as well as the structural features that could be responsible for its serine protease-like catalytic activity.
Failure of propranolol to prevent tilt-evoked systemic vasodilatation, adrenaline release and neurocardiogenic syncope
Authors: Eldadah Basil A. , Pechnik Sandra L. , Holmes Courtney S. , Moak Jeffrey P. , Saleem Ahmed M. , Goldstein David S.
Published: August 2006

In patients with neurocardiogenic syncope, head-up tilt often evokes acute loss of consciousness accompanied by vasodilatation, increased plasma adrenaline and systemic hypotension. Since hypotension increases adrenaline levels and adrenaline can produce skeletal muscle vasodilatation by activating β2 receptors, adrenaline might induce a positive feedback loop precipitating circulatory collapse. We hypothesized that propranolol, a non-selective β-blocker, would prevent adrenaline-induced vasodilatation and thereby prevent syncope. Eight subjects with recurrent neurocardiogenic syncope and previously documented tilt-induced syncope with elevated plasma adrenaline levels participated in the present study. Subjects underwent tilt table testing after receiving oral propranolol or placebo in a double-blind randomized crossover fashion. Haemodynamic and neurochemical variables were measured using intra-arterial monitoring, impedance cardiography, arterial blood sampling and tracer kinetics of simultaneously infused [3H]noradrenaline and [3H]adrenaline. The occurrence of tilt-induced neurally mediated hypotension and syncope, duration of tilt tolerance, extent of the decrease in SVRI (systemic vascular resistance index) and magnitude of plasma adrenaline increases did not differ between the propranolol and placebo treatment phases. SVRI was inversely associated with fractional increase in plasma adrenaline during both phases. One subject did not faint when on propranolol; this subject's response is discussed in the context of central effects of propranolol. In this small, but tightly controlled, study, propranolol did not prevent tilt-induced vasodilatation, syncope or elevated plasma adrenaline.
Can angiogenesis be exploited to improve stroke outcome? Mechanisms and therapeutic potential
Authors: Slevin Mark , Kumar Pat , Gaffney John , Kumar Shant , Krupinski Jerzy
Published: August 2006

Recent developments in our understanding of the pathophysiological events that follow acute ischaemic stroke suggest an important role for angiogenesis which, through new blood vessel formation, results in improved collateral circulation and may impact on the medium-to-long term recovery of patients. Future treatment regimens may focus on optimization of this process in the ischaemic boundary zones or ‘penumbra’ region adjacent to the infarct, where partially affected neurons exposed to intermediate perfusion levels have the capability of survival if perfusion is maintained or normalized. In this review, we present evidence that angiogenesis is a key feature of ischaemic stroke recovery and neuronal post-stroke re-organization, examine the signalling mechanisms through which it occurs, and describe the therapeutic potential of treatments aimed at stimulating revascularization and neuroprotection after stroke.
Relationships between changes in plasma lipid transfer proteins and apolipoprotein B-100 kinetics during fenofibrate treatment in the metabolic syndrome
Authors: Watts Gerald F. , Ji Juying , Chan Dick C. , Ooi Esther M. M. , Johnson Anthony G. , Rye Kerry-Anne , Barrett P. Hugh R.
Published: August 2006

The aim of the present study was to investigate the association between changes in apoB (apolipoprotein B-100) kinetics and plasma PLTP (phospholipid transfer protein) and CETP (cholesteryl ester transfer protein) activities in men with MetS (the metabolic syndrome) treated with fenofibrate. Eleven men with MetS underwent a double-blind cross-over treatment with fenofibrate (200 mg/day) or placebo for 5 weeks. Compared with placebo, fenofibrate significantly increased the FCRs (fractional catabolic rates) of apoB in VLDL (very-low-density lipoprotein), IDL (intermediate-density lipoprotein) and LDL (low-density lipoprotein) (all P<0.01), with no significant reduction (−8%; P=0.131) in VLDL-apoB PR (production rate), but an almost significant increase (+15%, P=0.061) in LDL-apoB PR. Fenofibrate significantly lowered plasma TG [triacylglycerol (triglyceride); P<0.001], the VLDL-TG/apoB ratio (P=0.003) and CETP activity (P=0.004), but increased plasma HDL (high-density lipoprotein)-cholesterol concentration (P<0.001) and PLTP activity (P=0.03). The increase in PLTP activity was positively associated with the increase in both LDL-apoB FCR (r=0.641, P=0.034) and PR (r=0.625, P=0.040), and this was independent of the fall in plasma CETP activity and lathosterol level. The decrease in CETP activity was positively associated with the decrease in VLDL-apoB PR (r=0.615, P=0.044), but this association was not robust and not independent of changes in PLTP activity and lathosterol levels. Hence, in MetS, the effects of fenofibrate on plasma lipid transfer protein activities, especially PLTP activity, may partially explain the associated changes in apoB kinetics.
β-Adrenergic receptor blockers and the treatment of vasovagal syncope: more nails in the coffin!
Authors: Mathias Christopher J.
Published: August 2006

β-Adrenergic receptor blockers are one of a number of therapeutic agents promoted as having beneficial effects in vasovagal syncope. In this issue of Clinical Science, Eldadah and co-workers have investigated the effect of the β-adrenergic receptor blocker propranolol in preventing syncope in a double-blind cross-over trial in eight subjects with a diagnosis based on tilt table testing and elevated plasma adrenaline levels during syncope. Of these, seven did not respond and the authors therefore suggest that this drug has no role in the management of vasovagal syncope. Their laboratory-based study, however, raises a number of issues regarding terminology, choice of subjects, the value and role of investigations directed towards diagnosis and in understanding pathophysiological mechanisms, and the relevance of such trials to individual subjects with vasovagal syncope.
High hydrogen content complex hydrides: A density-functional study
Authors: Vajeeston P. , Ravindran P. , Kjekshus A. , Fjellvåg H.
Published: August 2006

Density-functional-theory calculations within the generalized-gradient approximation are used to establish the ground-state structure, optimized geometry, and electronic structure for Mg(AlH4)2 and Mg(BH4)2. Among 28 structural arrangements used as inputs for structural optimization calculations, the experimentally known framework is reproduced for Mg(AlH4)2 (space group P3¯m1) with positional and unit-cell parameters in good agreement with the experimental findings. The crystal structure of Mg(BH4)2 is predicted, the ground-state framework being orthorhombic (space group Pmc21; Pearson symbol oP22 with a fascinating two-dimensional arrangement of Mg2+ ions and [BH4]2− tetrahedra. The formation energy for the predicted Mg(BH4)2 phase is investigated along different reaction pathways. The electronic structures reveal that Mg(AlH4)2 and Mg(AlH4)2 are insulators with calculated band gaps of around 4.5 and 6.2eV, respectively.
HXeCCH in Ar and Kr matrices
Authors: Tanskanen Hanna , Khriachtchev Leonid , Lundell Jan , Räsänen Markku
Published: August 2006

HXeCCH molecule is prepared in Ar and Kr matrices and characterized by IR absorption spectroscopy. The experiments show that HXeCCH can be made in another host than the polarizable Xe environment. The H–Xe stretching absorption of HXeCCH in Ar and Kr is blueshifted from the value measured in solid Xe. The maximum blueshifts are +44.9 and +32.3cm−1 in Ar and Kr, respectively, indicating stabilization of the H–Xe bond. HXeCCH has a doublet H–Xe stretching absorption measured in Xe, Kr, and Ar matrices with a splitting of 5.7, 13, and 14cm−1, respectively. Ab initio calculations for the 1:1 HXeCCH⋯Ng complexes (Ng=Ar, Kr, or Xe) are used to analyze the interaction of the hosts with the embedded molecule. These calculations support the matrix-site model where the band splitting observed experimentally is caused by specific interactions of the HXeCCH molecule with noble-gas atoms in certain local morphologies. However, the 1:1 complexation is unable to explain the observed blueshifts of the H–Xe stretching band in Ar and Kr matrices compared to a Xe matrix. More sophisticated computational approach is needed to account in detail the effects of solid environment.
Contraction of broken symmetries via Kac-Moody formalism
Authors: Daboul Jamil
Published: August 2006

I investigate contractions via Kac-Moody formalism. In particular, I show how the symmetry algebra of the standard two-dimensional Kepler system, which was identified by Daboul and Slodowy as an infinite-dimensional Kac-Moody loop algebra, and was denoted by H2, gets reduced by the symmetry breaking term, defined by the Hamiltonian H(β)=(1∕2m)(p12+p22)−α∕r−βr−1∕2cos((φ−γ)∕2). For this H(β) I define two symmetry loop algebras Li(β), i=1,2, by choosing the “basic generators” differently. These Li(β) can be mapped isomorphically onto subalgebras of H2, of codimension two or three, revealing the reduction of symmetry. Both factor algebras Li(β)∕Ii(E,β), relative to the corresponding energy-dependent ideals Ii(E,β), are isomorphic to so(3) and so(2,1) for E<0 and E>0, respectively, just as for the pure Kepler case. However, they yield two different nonstandard contractions as E→0, namely to the Heisenberg-Weyl algebra h3=w1 or to an Abelian Lie algebra, instead of the Euclidean algebra e(2) for the pure Kepler case. The above-noted example suggests a general procedure for defining generalized contractions, and also illustrates the “deformation contraction hysteresis,” where contraction which involves two contraction parameters can yield different contracted algebras, if the limits are carried out in different order.
Piezoelectric trace vapor calibrator
Authors: Verkouteren R. Michael , Gillen Greg , Taylor David W.
Published: August 2006

The design and performance of a vapor generator for calibration and testing of trace chemical sensors are described. The device utilizes piezoelectric ink-jet nozzles to dispense and vaporize precisely known amounts of analyte solutions as monodisperse droplets onto a hot ceramic surface, where the generated vapors are mixed with air before exiting the device. Injected droplets are monitored by microscope with strobed illumination, and the reproducibility of droplet volumes is optimized by adjustment of piezoelectric wave form parameters. Complete vaporization of the droplets occurs only across a 10°C window within the transition boiling regime of the solvent, and the minimum and maximum rates of trace analyte that may be injected and evaporated are determined by thermodynamic principles and empirical observations of droplet formation and stability. By varying solution concentrations, droplet injection rates, air flow, and the number of active nozzles, the system is designed to deliver—on demand—continuous vapor concentrations across more than six orders of magnitude (nominally 290fg∕lto1.05μg∕l). Vapor pulses containing femtogram to microgram quantities of analyte may also be generated. Calibrated ranges of three explosive vapors at ng/l levels were generated by the device and directly measured by ion mobility spectrometry (IMS). These data demonstrate expected linear trends within the limited working range of the IMS detector and also exhibit subtle nonlinear behavior from the IMS measurement process.
Compact multichannel neutral particle analyzer for measurement of energetic charge-exchanged neutrals in Alcator C-Mod
Authors: Tang V. , Liptac J. , Parker R. R. , Bonoli P. T. , Fiore C. L. , Granetz R. S. , Irby J. H. , Lin Y. , Wukitch S. J. , Team The Alcator C-Mod , Frenje J. A. , Leiter R. , Mcduffee S. , Petrasso R. D.
Published: August 2006

A four-channel compact neutral particle analyzer (CNPA) based on operating small Si diode detectors in pulse-height analysis (PHA) mode is used to measure energetic hydrogen minority ions with energies between ∼50 and 350keV stemming from ion-cyclotron range-of-frequency heated D(H) Alcator C-Mod plasmas with both active and passive charge exchange (CX). First core minority ion distribution results from Alcator C-Mod discharges and a detailed description of the diagnostic are presented. The diagnostic employs integrated electronics and fast digitization of the shaping amplifier voltage. The digitized data are stored for postshot PHA, which removes the constraints of real-time PHA and allows for improved performance via elimination of base line shift effects and potentially relieving pileup through Gaussian fitting routines. The CNPA is insensitive to the large gamma and neutron background in Alcator C-Mod discharges but is susceptible to the plasma’s soft x-ray flux. The soft x-ray flux limits the CNPA energy resolution to ∼15–20keV. A simple model is used to interpret the active CNPA data which permits rapid estimates of the core hydrogen minority temperatures and anisotropy with a time resolution of ∼100ms. Hydrogenlike boron is identified as an important electron donor for the CX signal.
Hydration of alcohol clusters in 1-propanol-water mixture studied by quasielastic neutron scattering and an interpretation of anomalous excess partial molar volume
Authors: Misawa M. , Inamura Y. , Hosaka D. , Yamamuro O.
Published: August 2006

Quasielastic neutron scattering measurements have been made for 1-propanol-water mixtures in a range of alcohol concentration from 0.0 to 0.167 in mole fraction at 25°C. Fraction α of water molecules hydrated to fractal surface of alcohol clusters in 1-propanol-water mixture was obtained as a function of alcohol concentration. Average hydration number Nws of 1-propanol molecule is derived from the value of α as a function of alcohol concentration. By extrapolating Nws to infinite dilution, we obtain values of 12–13 as hydration number of isolated 1-propanol molecule. A simple interpretation of structural origin of anomalous excess partial molar volume of water is proposed and as a result a simple equation for the excess partial molar volume is deduced in terms of α. Calculated values of the excess partial molar volumes of water and 1-propanol and the excess molar volume of the mixture are in good agreement with experimental values.
Manganese impurities in boron nitride
Authors: Assali L. V. C. , Machado W. V. M. , Justo J. F.
Published: August 2006

The authors carried an ab initio investigation on the properties of Mn impurities in BN, presenting results on stability, spin states, magnetic moment, hyperfine parameters, and formation and transition energies. Substitutional Mn in the cation site in BN was compared to that in GaN and GaAs. Due to the small BN lattice parameter, the Mn impurity is energetically more favorable in a divacancy site, as compared to the cation site. Although the Mn-divacancy complex has a high spin configuration, with a prevailing Mn d character, the transition energies lie deep in the gap, preventing a hole-mediated ferromagnetism.
Mechanical characterization device for in situ measurement of nanomechanical properties of micro/nanostructures
Authors: Singh Utkarsha , Prakash Vikas , Abramson Alexis R. , Chen Wei , Qu Liangti , Dai Liming
Published: August 2006

A characterization device was developed for nanomechanical testing on one-dimensional micro/nanostructures. The tool consists of a nanomanipulator, a three-plate capacitive transducer, and associated probes, and is operated inside a scanning electron microscope. The transducer independently measures force and displacement with micronewton and nanometer sale resolutions, respectively. Tensile testing of a polyaniline microfiber (diameter ∼1μm) demonstrated the capabilities of the system. Engineering stress versus strain curves exhibited two distinct regions with different Young’s moduli. Failure at the probe-sample weld occurred at ∼67MPa, suggesting that polyaniline microfibers exhibit a yield stress that is higher than most comparable bulk polymers.
Spin-wave relaxation in diluted magnetic semiconductors within the self-consistent Green’s function approach
Authors: Bunder J. E. , Sun Shih-Jye , Lin Hsiu-Hau
Published: August 2006

The authors employ a self-consistent Green’s function approach to investigate the spin-wave relaxation Γ(p) in diluted magnetic semiconductors. They find that the trend of the spin-wave relaxation strongly depends on the ratio of the itinerant and impurity spin densities. For density ratios in the Ruderman-Kittel-Kasuya-Yosida phase, Γ(p) decreases even though thermal fluctuations increase. On the other hand, in the strong coupling phase, an interesting peak structure appears. They discuss the implications of their numerical results for experiments.
Optimization of the surface and structural quality of N-face InN grown by molecular beam epitaxy
Authors: Koblmüller G. , Gallinat C. S. , Bernardis S. , Speck J. S. , Chern G. D. , Readinger E. D. , Shen H. , Wraback M.
Published: August 2006

The authors demonstrate the impact of growth kinetics on the surface and structural properties of N-face InN grown by molecular beam epitaxy. Superior surface morphology with step-flow growth features is achieved consistently under In-rich conditions in a low-temperature region of 500–540°C. Remarkably, off-axis x-ray rocking curve (ω scans) widths are found to be independent of the growth conditions. The band gap determined from optical absorption measurements of optimized InN is 0.651eV, while photoluminescence peak emission occurs at even lower energies of ∼0.626eV. Hall measurements show room temperature peak electron mobilities as high as 2370cm2∕Vs at a carrier concentration in the low 1017cm−3 region. Analysis of the thickness dependence of the carrier concentration demonstrates a n-type surface accumulation layer with a sheet carrier concentration of ∼3×1013cm−2.
Influence of N incorporation on In content in GaInNAs∕GaNAs quantum wells grown by plasma-assisted molecular beam epitaxy
Authors: Liu H. F. , Xiang N. , Chua S. J.
Published: August 2006

The authors investigated the synthesis of GaIn(N)As∕Ga(N)As multiple quantum wells by molecular beam epitaxy. Introducing N into the GaInAs appears to suppress the incorporation of In as indicated by reflective high-energy electron diffraction (RHEED). This effect is mainly due to the N-induced enhancement of In surface segregation at the growth front and is evidenced by the increasing damping rate of RHEED oscillations with N incorporation. The N-induced enhancement of In segregation in the GaInNAs quantum wells is confirmed by secondary-ion-mass spectroscopy and high-resolution x-ray diffractions, and its origin is discussed.
Silicon dioxide microcantilever with piezoresistive element integrated for portable ultraresoluble gaseous detection
Authors: Li Peng , Li Xinxin , Zuo Guomin , Liu Jian , Wang Yuelin , Liu Min , Jin Dazhong
Published: August 2006

Surface-stress sensing microcantilevers with on-chip signal readout are demanded for on-the-spot ultrasensitive biological/chemical detection. For enlarging the bending of the cantilever under surface stress induced by specific reaction, a novel SiO2 cantilever is developed which features much lower Young’s modulus than conventional Si or SiNx cantilevers. Thin single-crystalline-silicon piezoresistors are integrated with the SiO2 cantilevers for electric readout. For improving resolution, the piezoresistors are fully encapsulated by SiO2. Thus, the piezoresistors with SiO2 isolation show much lower leakage-related noise than those with p-n junction isolation. Following the description of microfabrication process, this letter gives the sensing model and discusses the thermal mechanism of the piezoresistive SiO2 cantilever. With a specific self-assembled monolayer functionalized on the cantilever surface, on-chip detection for the vapor of trinitrotoluene is performed with a resolution of about 20ppt (parts per trillion).
Enhanced field emission from imprinted carbon nanotube arrays
Authors: Liu Peng , Liu Liang , Wei Yang , Sheng Leimei , Fan Shoushan
Published: August 2006

The authors have fabricated patterned carbon nanotube arrays by a simple postgrowth imprinting method. Patterns with size down to 2μm can be formed with appropriate stamps. The imprinted array exhibited greatly enhanced field emission, the turn-on voltage was reduced to 0.9V∕μm from 2.8V∕μm of the as grown sample, and the aging behavior in long time emission was also lessened. The imprinted patterns were stable and able to withstand long time field emission measurement. This method could serve as a promising candidate for fast and low-cost production of patterned carbon nanotube arrays.
Thickness of shear bands in metallic glasses
Authors: Zhang Y. , Greer A. L.
Published: August 2006

A review of measurements and atomistic modeling shows that shear bands in metallic glasses have a characteristic thickness of ∼10nm. Such extreme localization of plastic deformation, within a thicker liquidlike layer implied by fracture-surface morphology, cannot have a thermal origin. By analogy with granular materials, the thickness is linked to the local structural rearrangements required to generate dilatation. This analysis suggests that first-coordination-shell clusters may be significant structural units in metallic glasses.
Silicon surface periodic structures produced by plasma flow induced capillary waves
Authors: Dojčinović I. P. , Kuraica M. M. , Obradović B. M. , Purić J.
Published: August 2006

Silicon single crystal surface modification by the action of nitrogen quasistationary compression plasma flow generated by a magnetoplasma compressor is studied. It has been found that highly oriented silicon periodic cylindrical shape structures are produced during a single pulse surface treatment. The periodical structure formation can be related to the driven capillary waves quenched during fast cooling and resolidification phase of the plasma flow interaction with silicon surface. These waves are induced on the liquid silicon surface due to the compression plasma flow intrinsic oscillations.
Properties of an optical multipass surface plasmon resonance technique
Authors: Su Chin B. , Kameoka Jun , Ilic B. , Chu Kung-Hui , Chang Kuang-An
Published: August 2006

A fiber optic four-pass surface plasmon resonance technique with an approach to increase the number of passes to any arbitrary number is described. Within multipass regime, reflections off the gold sample surface that reduce the reflectivity to less than 0.1% are achieved by using a fiber optic collimator, a reflector, and a corner cube prism. In this case, the optical beam emits from and returns to the collimator. This technique holds the potential for significantly increasing the detection sensitivity of surface plasmon resonance device.
Magnetic coupling in the mixture of different doped colossal magnetoresistances
Authors: Sun Shih-Jye , Lin Chen-Hung , Liao Po-Yu , Chou Hsiung
Published: August 2006

Uniform bulk mixtures of micron-sized La0.7Ce0.3MnO3 and La0.7Ca0.3MnO3 colossal magnetoresistance materials have been made by standard solid-state reaction. According to the x-ray diffraction and the energy dispersion spectrum, La0.9Ce0.3MnO3 is composed of (La1−εCeε)yMnO3+δ, CeO2, and Mn–O compounds, where (La1−εCeε)yMnO3+δ behaves as a ferromagnetic material and shows no atomic interdiffusion with La0.7Ca0.3MnO3. The temperature characteristics of magnetization measurement show that the canted antiferromagnetic interaction occurs at low temperatures. The dependence of these antiferromagnetic transition temperatures on the mixing ratio can be described by the molecular mean field theory, and this reveals the strength of magnetic couplings between magnetic grains.
Internal and effective stresses in nanocrystalline electrodeposited Ni
Authors: Van Petegem S. , Brandstetter S. , Van Swygenhoven H. , Martin J-L.
Published: August 2006

Stress reduction experiments performed during tensile deformation of nanocrystalline electrodeposited Ni demonstrate high values for the effective and the internal stress as compared to coarse grained metals and evidence the existence of a negative creep. The results are interpreted in terms of a thermally activated dislocation mechanism where propagation is hindered by pinning at grain boundaries.
Carrier storage time of milliseconds at room temperature in self-organized quantum dots
Authors: Marent A. , Geller M. , Bimberg D. , Vasi’ev A. P. , Semenova E. S. , Zhukov A. E. , Ustinov V. M.
Published: August 2006

Thermally activated hole emission from differently charged InAs∕GaAs quantum dots (QDs) was investigated by using deep level transient spectroscopy. In a sample with an additional AlGaAs barrier below the QD layer, a thermal activation energy of 560meV for hole emission from the QD ground states over the AlGaAs barrier is obtained. This large activation energy leads to a hole storage time at room temperature of about 5ms, which is in the order of magnitude of a typical dynamic random access memory (DRAM) refresh time.
Surface cleaning from laser-induced cavitation bubbles
Authors: Ohl Claus-Dieter , Arora Manish , Dijkink Rory , Janve Vaibhav , Lohse Detlef
Published: August 2006

When bubbles expand and collapse close to boundaries, a shear flow is generated which is able to remove particles from the surface, thus locally cleaning it. Here the authors demonstrate experimentally with microparticle tracking velocimetry that the strongest forcing of particles occurs during a very brief time interval of the bubble oscillation period. During this interval a jet flow impacts and spreads radially along the surface, thus transporting the particles with it.
Synaesthesia: The Prevalence of Atypical Cross-Modal Experiences
Authors: Simner Julia , Mulvenna Catherine , Sagiv Noam , Tsakanikos Elias , Witherby Sarah A , Fraser Christine , Scott Kirsten , Ward Jamie
Published: August 2006

Sensory and cognitive mechanisms allow stimuli to be perceived with properties relating to sight, sound, touch, etc, and ensure, for example, that visual properties are perceived as visual experiences, rather than sounds, tastes, smells, etc. Theories of normal development can be informed by cases where this modularity breaks down, in a condition known as synaesthesia. Conventional wisdom has held that this occurs extremely rarely (0.05% of births) and affects women more than men. Here we present the first test of synaesthesia prevalence with sampling that does not rely on self-referral, and which uses objective tests to establish genuineness. We show that (a) the prevalence of synaesthesia is 88 times higher than previously assumed, (b) the most common variant is coloured days, (c) the most studied variant (grapheme - colour synaesthesia)—previously believed most common—is prevalent at 1%, and (d) there is no strong asymmetry in the distribution of synaesthesia across the sexes. Hence, we suggest that female biases reported earlier likely arose from (or were exaggerated by) sex differences in self-disclosure.
Perception of Elliptic Biological Motion
Authors: Bidet-Ildei Christel , Orliaguet Jean-Pierre , Sokolov Alexander N , Pavlova Marina
Published: August 2006

We tested the ability of the mature visual system for discrimination between types of elliptic biological motion on the basis of event kinematics. Healthy adult volunteers were presented with point-light displays depicting elliptic motion when only a single dot, a moving point-light arm, or a whole point-light human figure was visible. The displays were created in accordance with the two-thirds power kinematic law ( natural motion), whereas the control displays violated this principle ( unnatural motion). On each trial, participants judged whether the display represented natural or unnatural motion. The findings indicate that adults are highly sensitive to violation of the two-thirds power kinematic law. Notably, participants can easily discriminate between natural and unnatural motions without recognising the stimuli, which suggests that people implicitly use kinematic information. Most intriguing, event recognition seems to diminish the capacity to judge whether event kinematics is unnatural. We discuss possible ways for a cross-talk between perception and production of biological movement, and the brain mechanisms involved in biological motion processing.
TNFα mediates the skeletal effects of thyroid-stimulating hormone
Authors: Hase Hidenori , Ando Takao , Eldeiry Leslie , Brebene Alina , Peng Yuanzhen , Liu Lanying , Amano Hitoshi , Davies Terry F. , Sun Li , Zaidi Mone , Abe Etsuko
Published: August 2006

We have shown recently that by acting on the thyroid-stimulating hormone (TSH) receptor (TSHR), TSH negatively regulates osteoclast differentiation. Both heterozygotic and homozygotic TSHR null mice are osteopenic with evidence of enhanced osteoclast differentiation. Here, we report that the accompanying elevation of TNFα, an osteoclastogenic cytokine, causes the increased osteoclast differentiation. This enhancement in TSHR
−/−
and TSHR
+/−
mice is abrogated in compound TSHR
−/−
/TNFα
−/−
and TSHR
+/−
/TNFα
+/−
mice, respectively. In parallel studies, we find that TSH directly inhibits TNFα production, reduces the number of TNFα-producing osteoclast precursors, and attenuates the induction of TNFα expression by IL-1, TNFα, and receptor activator of NF-κB ligand. TSH also suppresses osteoclast formation in murine macrophages and RAW-C3 cells. The suppression is more profound in cells that overexpress the TSHR than those transfected with empty vector. The overexpression of ligand-independent, constitutively active TSHR abrogates osteoclast formation even under basal conditions and in the absence of TSH. Finally, IL-1/TNFα and receptor activator of NF-κB ligand fail to stimulate AP-1 and NF-κB binding to DNA in cells transfected with TSHR or constitutively active TSHR. The results suggest that TNFα is the critical cytokine mediating the downstream antiresorptive effects of TSH on the skeleton.