bluuebunny/crossref_metadata_2025 huggingface dataset:
The concept of vulnerability in disaster research
Authors: Levine Carol
Published: November 2004

The concept of vulnerability in research derives from a specific set of historical circumstances relating to abuses in biomedical research. Now so many people and groups have been labeled vulnerable that the concept has lost much of its force. In disaster research, participants should not be automatically considered vulnerable unless they are legally designated as such, for example, children. Instead specific aspects of the research should be thoroughly examined. Examples are the potential for the participants to be pressured to participate in several protocols, political or social turmoil surrounding the disaster, and cognitive impairments or mental health problems. In addition to a careful consent process, there should be procedures in place to provide assistance to participants who experience serious distress.
Gravity waves around the subtropical jet of the southern winter in an atmospheric general circulation model
Authors: Kawatani Yoshio , Takahashi Masaaki , Tokioka Tatsushi
Published: November 2004

Gravity wave (GW) activities around the subtropical jet of the Southern winter (June) are analyzed using Atmospheric General Circulation Model outputs of T106L60, in order to clarify roles of GWs in maintaining the zonal mean zonal wind. Dominant GWs are characterized with periods of 10–24 hours relative to the ground, and with horizontal and vertical wavelengths of about 600–700 km and 2.2–4.4 km, respectively. These GWs propagate both upward and downward from the jet, and westward relative to the mean zonal wind. Most of the upward propagating waves do not reach the upper stratosphere due to negative vertical wind shear of the zonal wind in the lower stratosphere. Dominant upward fluxes of easterly momentum due to the non‐stationary GWs extend zonally along 30°S above the jet. Remarkable EP‐flux convergence due mostly to these GWs is seen around 100 hPa at 30°S, and explains up to 30% of the total EP‐flux convergence.
Analysis of spatial distribution in tropospheric temperature trends
Authors: Agudelo Paula A. , Curry Judith A.
Published: November 2004

Regional patterns in tropospheric and sea surface temperature (SST) trends are examined for the period 1979–2001 using MSU, NCEP‐NCAR, ECMWF reanalyses, NOAA OI SST, and the CARDS radiosonde data set. Trends are estimated using a nonparametric approach. Substantial regional variability in temperature trends is seen in all data sets, with the magnitude of the variability (including substantial regions with cooling trends) far exceeding the average warming trend. The global analyses from MSU and reanalyses are used to identify sampling problems in using radiosonde network to infer global trends. Analysis of tropospheric temperature trends concurrent with trends in SST shows regions where the signs disagree for both surface cooling and warming. Interpretation of these differing trends using the reanalyses suggest that the models used for the reanalyses are simulating the necessary dynamics/thermodynamics that could lead to a tropospheric cooling in contrast to a surface warming (and vice versa).
Greenhouse forcing outweighs decreasing solar radiation driving rapid temperature rise over land
Authors: Philipona Rolf , Dürr Bruno
Published: November 2004

Since 1988, surface temperature over land in Europe increased three times faster than the northern hemisphere average. Here we contrast surface climatic and radiative parameters measured in central Europe over different time periods, including the extreme summer 2003, to pinpoint the role of individual radiative forcings in temperature increases. Interestingly, surface solar radiation rather decreases since 1981. Also, on an annual basis no net radiative cooling or warming is observed under changing cloud amounts. However, high correlation (rT = 0.86) to increasing temperature is found with total heating radiation at the surface, and very high correlation (rT = 0.98) with cloud‐free longwave downward radiation. Preponderance of longwave downward radiative forcing suggests rapidly increasing greenhouse warming, which outweighs the decreasing solar radiation measured at the surface and drives rapid temperature increases over land.
Pacific dominance to global air‐sea CO2 flux variability: A novel atmospheric inversion agrees with ocean models
Authors: McKinley G. A. , Rödenbeck C. , Gloor M. , Houweling S. , Heimann M.
Published: November 2004

We address an ongoing debate regarding the geographic distribution of interannual variability in ocean ‐ atmosphere carbon exchange. We find that, for 1983–1998, both novel high‐resolution atmospheric inversion calculations and global ocean biogeochemical models place the primary source of global CO2 air‐sea flux variability in the Pacific Ocean. In the model considered here, this variability is clearly associated with the El Niño/Southern Oscillation cycle. Both methods also indicate that the Southern Ocean is the second‐largest source of air‐sea CO2 flux variability, and that variability is small throughout the Atlantic, including the North Atlantic, in contrast to previous studies.
Relationship between atmospheric circulation and winter precipitation δ18O in central New York State
Authors: Burnett Adam W. , Mullins Henry T. , Patterson William P.
Published: November 2004

Oxygen isotope values of meteoric precipitation (δ18O) are strongly influenced by water vapor source and trajectory history, and can therefore be used as a tool for the reconstruction of atmospheric circulation. However, this approach requires an understanding of how differing patterns of atmospheric circulation influence precipitation δ18O. This study examines the relationship between atmospheric circulation and winter precipitation δ18O in central New York State. Circulation back trajectories, weather maps, and δ18O values for 132 precipitation samples were examined to determine the circulation type for each event. Lake‐effect precipitation, which generated the lowest δ18O values, featured low pressure over New England and northwesterly flow over the Great Lakes. Events with the highest δ18O values were associated with low pressure north of New York and strong southerly flow within the warm sector. Less frequent were the Atlantic coastal and warm frontal overrunning events, both of which yielded relatively depleted precipitation.
Fractal interpolation of rain rate time series
Authors: Paulson Kevin S.
Published: November 2004

Meteorological radar databases exist providing rain rate maps over areas with a sampling period of 2–15 min. Such two‐dimensional, rain rate map time series would have wide application in the simulation of rain scatter and attenuation of millimeter‐wave radio networks, if the sampling period were considerably shorter, i.e., of the order of 10 s or less. However, scanning a large radar at this rate is physically infeasible. This paper investigates a stochastic numerical method to interpolate point rain rate time series to shorter sampling periods while conserving the expected first‐ and second‐order statistics. The proposed method should generally be applicable to the temporal interpolation of radar‐derived rain rate maps. The method is based on the experimentally measured simple‐scaling properties of log rain rate time series. It is tested against 9 gauge years of rapid response drop‐counting rain gauge data, with a 10 s integration time, collected in the southern UK. The data are subsampled to yield time series with a 10 s rain rate measurement every 320, 640, and 1280 s. The subsampled time series are then interpolated back to a 10 s sample interval, and the first‐ and second‐order statistics are compared with the original time series.
MAX‐DOAS O4 measurements: A new technique to derive information on atmospheric aerosols—Principles and information content
Authors: Wagner T. , Dix B. , Friedeburg C. v. , Frieß U. , Sanghavi S. , Sinreich R. , Platt U.
Published: November 2004

Multi AXis Differential Optical Absorption Spectroscopy (MAX‐DOAS) observations of the oxygen dimer O4 which can serve as a new method for the determination of atmospheric aerosol properties are presented. Like established methods, e.g., Sun radiometer and LIDAR measurements, MAX‐DOAS O4 observations determine optical properties of aerosol under atmospheric conditions (not dried). However, the novel technique has two major advantages: It utilizes differential O4 absorption structures and thus does not require absolute radiometric calibration. In addition, O4 observations using this method provide a new kind of information: since the atmospheric O4 profile depends strongly on altitude, they can yield information on the atmospheric light path distribution and in particular on the atmospheric aerosol profile. From O4 observations during clear days and from atmospheric radiative transfer modeling, we conclude that our new method is especially sensitive to the aerosol extinction close to the ground. In addition, O4 observations using this method yield information on the penetration depth of the incident direct solar radiation. O4 observations at different azimuth angles can also provide information on the aerosol scattering phase function. We found that MAX‐DOAS O4 observations are a very sensitive method: even aerosol extinction below 0.001 could be detected. In addition to the O4 absorptions we also investigated the magnitude of the Ring effect and the (relative) intensity. Both quantities yield valuable further information on atmospheric aerosols. From the simultaneous analysis of the observed O4 absorption and the measured intensity, in particular, information on the absorbing properties of the aerosols might be derived. The aerosol information derived from MAX‐DOAS observations can be used for the quantitative analysis of various trace gases also analyzed from the measured spectra.
Modeling atmospheric sulfur over the Northern Hemisphere during the Aerosol Characterization Experiment 2 experimental period
Authors: Benkovitz Carmen M. , Schwartz Stephen E. , Jensen Michael P. , Miller Mark A. , Easter R. C. , Bates Timothy S.
Published: November 2004

A high‐resolution (1° × 1°, 27 vertical levels) Eulerian chemical transport and transformation model for sulfate, SO2, and related species driven by analyzed forecast meteorological data has been run for the Northern Hemisphere for June–July 1997 and extensively evaluated with observational data, mainly from air quality and precipitation chemistry networks. For ∼5000 evaluations, 50% of the modeled sulfate 24‐hour mixing ratios were within a factor of 1.85 of the observations; 50% of ∼328 concurrent subgrid observations were within a factor of 1.33. Much greater subgrid variation for 24‐hour SO2 mixing ratios (50% of ∼3552 observations were within a factor of 2.32) reflects high variability of this primary species; for ∼12600 evaluations, 50% of modeled mixing ratios were within a factor of 2.54 of the observations. These results indicate that a substantial fraction of the modeled and observed differences is due to subgrid variation and/or measurement error. Sulfate mixing ratios are identified by source type (biogenic, volcanic, and anthropogenic) and production mechanism (primary and by gas‐phase and aqueous‐phase oxidation). Examination of key diagnostics showed substantial variation for the different types of sulfur, e.g., SO2 aqueous‐phase oxidation rates of 29–102% d−1 and sulfate residence times of 4–9 days. Volcanic emissions contributed 10% of the sulfate burden and 6% of emissions, because the elevated release allows large fractional conversion of SO2 and long residence time. Biogenic SO2 was generally at lower concentrations than H2O2, resulting in efficient aqueous‐phase oxidation; this source type contributed 13% of emissions but only 5% of sulfate burden. Anthropogenic sources were the dominant contributors to sulfur emissions (80%) and sulfate burden (84%).
Simulation of the Martian dust cycle with the GFDL Mars GCM
Authors: Basu Shabari , Richardson Mark I. , Wilson R. John
Published: November 2004

The Martian seasonal dust cycle is examined with a general circulation model (GCM) that treats dust as a radiatively and dynamically interactive trace species. Dust injection is parameterized as being due to convective processes (such as dust devils) and model‐resolved wind stresses. Size‐dependent dust settling, transport by large‐scale winds and subgrid scale diffusion, and radiative heating due to the predicted dust distribution are treated. Multiyear Viking and Mars Global Surveyor air temperature data are used to quantitatively assess the simulations. Varying the three free parameters for the two dust injection schemes (rate parameters for the two schemes and a threshold for wind‐stress lifting), we find that the highly repeatable northern spring and summer temperatures can be reproduced by the model if the background dust haze is supplied by either convective lifting or by stress lifting with a very low threshold and a low injection rate. Dust injection due to high‐threshold, high‐rate stress lifting must be added to these to generate spontaneous and variable dust storms. In order to supply the background haze, widespread and ongoing lifting is required by the model. Imaging data provide a viable candidate mechanism for convective lifting, in the form of dust devils. However, observed nonconvective lifting systems (local storms, etc.) appear insufficiently frequent and widespread to satisfy the role. On the basis of the model results and thermal and imaging data, we suggest that the background dust haze on Mars is maintained by convective processes, specifically, dust devils. Combining the convective scheme and high‐threshold stress lifting, we obtain a “best fit” multiyear simulation, which produces a realistic thermal state in northern spring and summer and, for the first time, spontaneous and interannually variable global dust storms.
Effect of large woody debris configuration on three‐dimensional flow structure in two low‐energy meander bends at varying stages
Authors: Daniels Melinda D. , Rhoads Bruce L.
Published: November 2004

Few process‐based studies have investigated the effects of large woody debris (LWD) on the fluvial dynamics of obstructed meander bends. This field‐based study examines the influence of LWD on spatial patterns of three‐dimensional (3‐D) flow in two meander bends of a low‐energy stream in northern Illinois. The results of this study indicate that LWD substantially modifies 3‐D flow structure through low‐gradient meander bends. However, the detailed nature of the flow modification is highly dependent on the particular arrangement, density, and mobility of LWD in a bend. In one of the study bends the LWD primarily functions as roughness elements that reduce the velocity of flow and constrain the high‐velocity core and helical motion to the center of the channel. In the other study bend, LWD obstructions act to strongly deflect the flow away from the outer bank rather than simply increasing the resistance to flow along this bank. While results indicate that LWD influences patterns of three‐dimensional flow at all stages, the degree of influence appears to change with stage; the overall pattern of three‐dimensional flow remains constant, but the spatial extent of the pattern increases with increasing stage.
Multidrug transporter activity in lymphocytes
Authors: Elliott James I , Raguz Selina , Higgins Christopher F
Published: November 2004

Multidrug transporters play a dual role in haematopoietic cells, mediating the efflux of xenobiotics and regulating cell migration.

For several reasons including the lack of specific antibodies, reports of multidrug transporter distribution on lymphocytes conflict. Murine B cells have been reported to completely lack transporter activity.

Through analysis of parental and ‘knockout’ mice we show that, contrary to previous studies, murine B and T lymphocytes possess at least three active multidrug transporters and also a hitherto unrecognised drug‐specific import activity.

Surprisingly, the drug specificity of P‐glycoprotein appears cell type dependent. The data indicate that a range of developmentally regulated, multidrug transporters can impose a barrier to treatment of immune disorders.

British Journal of Pharmacology (2004) 143, 899–907. doi:10.1038/sj.bjp.0705940
Computational‐fluid‐dynamics (CFD) modelling of an industrial crystallizer: application to the forced‐circulation reactor
Authors: Essemiani Karim , De Traversay Christelle , Gallot Jean Claude
Published: November 2004

The CFD (computational fluid dynamics) technique is used to describe the mixing conditions in a pilot‐scale FCC (forced‐circulation crystallizer) and to study the impact of flow rate and aspect ratio on local flow conditions and RTD (residence‐time distribution) in the crystallizer. The analysis adequately predicts the oscillating flow and two‐phase (gas–liquid) interaction at the free surface. A comparison has been made between the CFD predictions and models of RTD. The results support the use of CFD methodology as an aid to optimization of commercial‐scale FCC design.
Effects of pH on Helicobacter pylori binding to human gastric mucins: identification of binding to non-MUC5AC mucins
Authors: LINDÉN Sara , MAHDAVI Jafar , HEDENBRO Jan , BORÉN Thomas , CARLSTEDT Ingemar
Published: November 2004

Helicobacter pylori causes gastritis, peptic ulcer disease and gastric cancer. The microbe is found in the gastric mucus layer where a pH gradient ranging from acidic in the lumen to neutral at the cell surface is maintained. The aim of the present study was to investigate the effects of pH on H. pylori binding to gastric mucins from healthy individuals. At pH 3, all strains bound to the most charged MUC5AC glycoform and to a putative mucin of higher charge and larger size than subunits of MUC5AC and MUC6, irrespective of host blood-group. In contrast, at pH 7.4 only Leb-binding BabA-positive strains bound to Leb-positive MUC5AC and to smaller mucin-like molecules, including MUC1. H. pylori binding to the latter component(s) seems to occur via the H-type-1 structure. All strains bound to a proteoglycan containing chondroitin sulphate/dermatan sulphate side chains at acidic pH, whereas binding to secreted MUC5AC and putative membrane-bound strains occurred both at neutral and acidic pH. The binding properties at acidic pH are thus common to all H. pylori strains, whereas mucin binding at neutral pH occurs via the bacterial BabA adhesin and the Leb antigen/related structures on the glycoprotein. Our work shows that microbe binding to membrane-bound mucins must be considered in H. pylori colonization, and the potential of these glycoproteins to participate in signalling events implies that microbe binding to such structures may initiate signal transduction over the epithelial layer. Competition between microbe binding to membrane-bound and secreted mucins is therefore an important aspect of host–microbe interaction.
Membrane insertion of the N-terminal α-helix of equinatoxin II, a sea anemone cytolytic toxin
Authors: GUTIÉRREZ-AGUIRRE Ion , BARLIČ Ariana , PODLESEK Zdravko , MAČEK Peter , ANDERLUH Gregor , GONZÁLEZ-MAÑAS Juan M.
Published: November 2004

Equinatoxin II (Eqt-II) is a member of the actinoporins, a unique family of cytotoxins comprising 20 kDa pore-forming proteins isolated from sea anemones. Actinoporins bind preferentially to lipid membranes containing sphingomyelin, and create cation-selective pores by oligomerization of three to four monomers. Previous studies have shown that regions of Eqt-II crucial for its cytolytic mechanism are an exposed aromatic cluster and the N-terminal region containing an amphipathic α-helix. In the present study, we have investigated the transfer of the N-terminal α-helix into the lipid membrane by the use of three mutants containing an additional tryptophan residue in different positions within the amphipathic α-helix (Ile18→Trp, Val22→Trp and Ala25→Trp). The interaction of the mutants with different model systems, such as lipid monolayers, erythrocytes and ghost membranes, was extensively characterized. Intrinsic fluorescence measurements and the use of vesicles containing brominated phospholipids indicated a deep localization of the N-terminal amphipathic helix in the lipid bilayer, except for the case of Val22→Trp. This mutant is stabilized in a state immediately prior to final pore formation. The introduction of additional tryptophan residues in the sequence of Eqt-II has proved to be a suitable approach to monitor the new environments that surround defined regions of the molecule upon membrane interaction.
Characterization of Staufen 1 ribonucleoprotein complexes
Authors: BRENDEL Cornelia , REHBEIN Monika , KREIENKAMP Hans-Jürgen , BUCK Friedrich , RICHTER Dietmar , KINDLER Stefan
Published: November 2004

In Drosophila oocytes and neuroblasts, the double-stranded RNA binding protein Staufen assembles into ribonucleoprotein particles, which mediate cytoplasmic mRNA trafficking and translation. Two different mammalian orthologues also appear to reside in distinct RNA-containing particles. To date, relatively little is known about the molecular composition of Staufen-containing ribonucleoprotein complexes. Here, we have used a novel one-step affinity purification protocol to identify components of Staufen 1-containing particles. Whereas the nucleocytoplasmic RNA-binding protein nucleolin is linked to Staufen in an RNA-dependent manner, the association of protein phosphatase 1, the microtubule-dependent motor protein kinesin and several components of the large and small ribosomal subunits with Staufen ribonucleoprotein complexes is RNA-independent. Notably, all these components do not co-purify with a second RNA-binding protein, hnRNPK (heterogeneous ribonucleoprotein K), demonstrating the high specificity of the purification protocol. Furthermore, pull-down and immunoprecipitation experiments suggest a direct interaction between Staufen 1 and the ribosomal protein P0 in vitro as well as in cells. In cell fractionation and sucrose gradient assays, Staufen co-fractionates with intact ribosomes and polysomes, but not with the isolated 40 S ribosomal subunit. Taken together, these findings imply that, in the cytoplasm of mammalian cells, an association with the ribosomal P-stalk protein P0 recruits Staufen 1 into ribosome-containing ribonucleoprotein particles, which also contain kinesin, protein phosphatase 1 and nucleolin.
Antizyme induction mediates feedback limitation of the incorporation of specific polyamine analogues in tissue culture
Authors: MITCHELL John L. A. , SIMKUS Carrie L. , THANE Thynn K. , TOKARZ Phil , BONAR Michelle M. , FRYDMAN Benjamin , VALASINAS Aldonia L. , REDDY Venodhar K. , MARTON Laurence J.
Published: November 2004

Spermidine, spermine and putrescine are essential for mammalian cell growth, and there has been a pervasive effort to synthesize analogues of these polyamines that will disrupt their function and serve as tools to inhibit cell proliferation. Recently, we demonstrated that a number of such polyamine analogues are also capable of inducing the regulatory protein AZ (antizyme). In the present study the incorporation of a few sample analogues [mimics of bis(ethyl)spermine] was shown to be significantly limited by a decrease in the Vmax for the polyamine transport system in response to analogue-induced AZ. This creates an unusual circumstance in which compounds that are being designed for therapeutic use actually inhibit their own incorporation into targeted cells. To explore the impact of this feedback system, cultures of rat hepatoma HTC cells were pre-treated to exhibit either low or high polyamine uptake activity and then exposed to polyamine analogues. As predicted, regardless of initial uptake activity, all cultures eventually achieved the same steady-state levels of the cellular analogue and AZ. Importantly, analogue-induced AZ levels remained elevated with respect to controls even after the native polyamines were reduced by more than 70%. To model the insufficient AZ expression found in certain tumours, GS-CHO (GS Chinese-hamster ovary) cells were transfected to express high levels of exogenic AZI (AZ inhibitor). As anticipated, this clone incorporated significantly higher levels of the polyamine analogues examined. This study reveals a potential limitation in the use of polyamine-based compounds as therapeutics, and strategies are presented to either circumvent or exploit this elegant transport feedback system.
Diabetic cardiomyopathy: mechanisms, diagnosis and treatment
Authors: HAYAT Sajad A. , PATEL Billal , KHATTAR Rajdeep S. , MALIK Rayaz A.
Published: November 2004

Independent of the severity of coronary artery disease, diabetic patients have an increased risk of developing heart failure. This clinical entity has been considered to be a distinct disease process referred to as ‘diabetic cardiomyopathy’. Experimental studies suggest that extensive metabolic perturbations may underlie both functional and structural alterations of the diabetic myocardium. Translational studies are, however, limited and only partly explain why diabetic patients are at increased risk of cardiomyopathy and heart failure. Although a range of diagnostic methods may help to characterize alterations in cardiac function in general, none are specific for the alterations in diabetes. Treatment paradigms are very much limited to interpretation and translation from the results of interventions in non-diabetic patients with heart failure. This suggests that there is an urgent need to conduct pathogenetic, diagnostic and therapeutic studies specifically in diabetic patients with cardiomyopathy to better understand the factors which initiate and progress diabetic cardiomyopathy and to develop more effective treatments.
The role of insulin and the adipocytokines in regulation of vascular endothelial function
Authors: RITCHIE Stuart A. , EWART Marie-Ann , PERRY Colin G. , CONNELL John M. C. , SALT Ian P.
Published: November 2004

Vascular integrity in the healthy endothelium is maintained through the release of a variety of paracrine factors such as NO (nitric oxide). Endothelial dysfunction, characterized by reduced NO bioavailability, is associated with obesity, insulin resistance and Type II diabetes. Insulin has been demonstrated to have direct effects on the endothelium to increase NO bioavailability. Therefore altered insulin signalling in the endothelium represents a candidate mechanism underlying the association between insulin resistance and endothelial dysfunction. In recent years, it has become apparent that insulin sensitivity is regulated by the adipocytokines, a group of bioactive proteins secreted by adipose tissue. Secretion of adipocytokines is altered in obese individuals and there is increasing evidence that the adipocytokines have direct effects on the vascular endothelium. A number of current antidiabetic strategies have been demonstrated to have beneficial effects on endothelial function and to alter adipocytokine concentrations in addition to their effects on glucose homoeostasis. In this review we will explore the notion that the association between insulin resistance and endothelial dysfunction is accounted for by adipocytokine action on the endothelium. In addition, we examine the effects of weight loss, exercise and antidiabetic drugs on adipocytokine availability and endothelial function.
Hall effect, magnetization, and conductivity of Fe3O4 epitaxial thin films
Authors: Reisinger D. , Majewski P. , Opel M. , Alff L. , Gross R.
Published: November 2004

Magnetite epitaxial thin films have been prepared by pulsed laser deposition on MgO and Si substrates. The magnetic and electrical properties of these epitaxial films are close to those of single crystals. For 40-50 nm thick films, the saturation magnetization and electrical conductivity are ∼450emu∕cm3 and 225Ω−1cm−1 at room temperature, respectively. The Verwey transition temperature is 117K. The Hall effect data yield an electron concentration corresponding to 0.22 electrons per formula unit at room temperature. Both normal and anomalous Hall effect have been found to have negative sign.
Fabrication and electrical characteristics of high-performance ZnO nanorod field-effect transistors
Authors: Park Won Il , Kim Jin Suk , Yi Gyu-Chul , Bae M. H. , Lee H.-J.
Published: November 2004

We report on fabrication and electrical characteristics of high-mobility field-effect transistors (FETs) using ZnO nanorods. For FET fabrications, single-crystal ZnO nanorods were prepared using catalyst-free metalorganic vapor phase epitaxy. Although typical ZnO nanorod FETs exhibited good electrical characteristics, with a transconductance of ∼140nS and a mobility of 75cm2∕Vs, the device characteristics were significantly improved by coating a polyimide thin layer on the nanorod surface, exhibiting a large turn-ON/OFF ratio of 104–105, a high transconductance of 1.9μS, and high electron mobility above 1000cm2∕Vs. The role of the polymer coating in the enhancement of the devices is also discussed.
Continuous microfluidic immunomagnetic cell separation
Authors: Inglis David W. , Riehn R. , Austin R. H. , Sturm J. C.
Published: November 2004

We present a continuous-flow microfluidic device that enables cell by cell separation of cells selectively tagged with magnetic nanoparticles. The cells flow over an array of microfabricated magnetic stripes, which create a series of high magnetic field gradients that trap the magnetically labeled cells and alter their flow direction. The process was observed in real time using a low power microscope. The device has been demonstrated by the separation of leukocytes from whole human blood.
Semiconducting-polymer-based position-sensitive detectors
Authors: Kabra D. , Singh Th. B. , Narayan K. S.
Published: November 2004

We demonstrate the utility of the organic semiconducting polymers as active media for light-sensitive position-sensitive detectors (PSDs). The characteristics of these PSDs include reasonable linearity and photoresponsivity over a large range of distance, photovoltaic mode of operation, and other advantages such as nonrigid substrates and absence of any other transporting-conducting coating layer. These devices utilize the formation of Al-polymer Schottky-type photoactive interface as a common backcontact. We demonstrate results for poly(3-hexylthiophene)-based PSDs of different interelectrode spacings where the photovoltaic signals as a function of incident-beam position are linear over the entire range.
Bragg gratings in silicon-on-insulator waveguides by focused ion beam milling
Authors: Moss D. J. , Ta’eed V. G. , Eggleton B. J. , Freeman D. , Madden S. , Samoc M. , Luther-Davies B. , Janz S. , Xu D.-X.
Published: November 2004

We report Bragg grating structures fabricated by focused ion beam milling in optical waveguides, and demonstrate that they can be used as a powerful diagnostic of optical modes in very high index waveguides. We show that higher-order lossy modes, which can be present in large numbers even in single-moded silicon-on-insulator waveguides, can dramatically affect the optical transmission spectra of Bragg gratings in these waveguides, even though these modes are normally not observable. Our results not only illuminate challenges to realize practical gratings in high index waveguides, but raise the possibility of devices based on mode conversion to extremely high order modes.
Fabrication of three-dimensional photonic crystal with alignment based on electron beam lithography
Authors: Subramania G. , Lin S. Y.
Published: November 2004

We demonstrate the fabrication of a three-dimensional woodpile photonic crystal in the near-infrared using a layer-by-layer approach involving electron beam lithography and spin on glass planarization. The alignment accuracy between the first and the fifth layer is within 10% of the lattice spacing as measured from cross section scanning-electron-microscopy images. Optical reflectivity measurements reveal peaks consistent with the photonic gap frequency. The method offers a way of rapid prototyping full three-dimensional photonic band gap devices with considerable flexibility of materials choice. Moreover, lattice structure that can operate at wavelengths into the visible can be fabricated using this approach.
Can correlated substitution enhance the Curie temperature in diluted magnetic semiconductors?
Authors: Bouzerar Georges , Ziman Timothy , Kudrnovský Josef
Published: November 2004

We present a quantitative theory for ferromagnetism in diluted magnetic semiconductors under the assumption that the positions of the substitutional magnetic impurities are correlated. The theory predicts that room-temperature ferromagnetism should be possible in macroscopically homogeneous samples of MnxGa1−xAs if the probability of pairs of Mn impurities on neighboring Ga sites is sufficiently enhanced. The theory predicts similar increases in the Curie temperatures for MnxGa1−xN but the temperatures remain lower than in MnxGa1−xAs.
Passivation of organic light-emitting diodes with aluminum oxide thin films grown by plasma-enhanced atomic layer deposition
Authors: Yun Sun Jin , Ko Young-Wook , Lim Jung Wook
Published: November 2004

The passivation of organic light-emitting diodes (OLEDs) with Al2O3 films containing small amounts of N (Al2O3:N) was investigated by plasma-enhanced atomic layer deposition using a direct rf plasma with a short pulse time. Luminance—voltage and current density—voltage curves of an OLED passivated with a 300nm Al2O3:N film at 60°C remained unchanged compared to those of nonpassivated OLED and 96% of the initial luminance were maintained even after operating for 850h at 14mA∕cm2. The lifetime of an OLED with an 80°C Al2O3:N film was 650h, 6.2 times longer than that of a nonpassivated sample, although the luminance—voltage characteristics of the OLED were altered to a considerable extent.
Nanoscale polymer recognition by spectral signature in scattering infrared near-field microscopy
Authors: Taubner T. , Hillenbrand R. , Keilmann F.
Published: November 2004

We demonstrate—for a typical polymer vibrational infrared line—that scattering-type “apertureless” optical near-field microscopy features a spectral signature that differs characteristically from far-field absorption. Theory predicts a dispersion-like amplitude spectrum (besides an absorption-like, bell-shaped phase spectrum). This signature is experimentally verified for a vibrational resonance of PMMA, by probing with a CO laser tuned from 5.5 to 6 μm. We apply this signature to identify PMMA in the near-field imaging of a nanostructured PMMA/PS polymer blend, at <70nm resolution. Our results suggest a potentially quantitative chemometry based on near-field infrared vibrational fingerprints with spatial resolution that could reach 10 nm.
Positive temperature coefficient of resistivity in Pt∕(Ba0.7Sr0.3)TiO3∕YBa2Cu3O7-x capacitors
Authors: Yang Hao , Chen Bin , Miao Jun , Zhao Li , Xu Bo , Dong Xiaoli , Cao Lixin , Qiu Xianggang , Zhao Bairu
Published: November 2004

Pt ∕ ( Ba 0.7 Sr 0.3 ) TiO 3 ( BST ) ∕ YBa 2 Cu 3 O 7 - x ( YBCO ) capacitors were fabricated on (001) LaAlO3 substrates. The leakage current density-electric field characteristics were measured in the temperature range from 20 to 300K. In the electric field region of >0.7MV∕cm for positively biased Pt electrode and >1.4MV∕cm for negatively biased Pt electrode, the leakage current shows space-charge-limited-current behavior from 20 to 250K. Meanwhile a positive temperature coefficient of resistivity (PTCR) in the temperature range from 20 to 150K was observed and attributed to the strong negative temperature dependence of the dielectric constant of BST thin films.
Interface-oxygen-loss-controlled voltage offsets in epitaxial Pb(Zr0.52Ti0.48)O3 thin-film capacitors with La0.7Sr0.3MnO3 electrodes
Authors: Wu Wenbin , Wong K. H. , Choy C. L.
Published: November 2004

Epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) thin-film capacitors with La0.7Sr0.3MnO3 (LSMO) electrodes have been grown on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 (001) substrates by pulsed-laser deposition. The process-induced imprint behavior in the ferroelectric capacitors was examined by in situ and ex situ annealing at various conditions. It was found that for the capacitors in situ annealed at reduced oxygen pressures, where the LSMO electrodes are stable, voltage offsets in the polarization-electric field hysteresis loops were observed only for those treated at temperatures higher than the Curie temperature. At lower temperatures, the oxygen loss may be suppressed by stresses arising primarily from the paraelectric-to-ferroelectric transformation. However, for the capacitors ex situ annealed at the same low temperature, large voltage offsets were induced due to the oxygen instability of the LSMO electrodes. We show evidence that the imprint is caused by oxygen loss at the PZT∕LSMO interface, and closely related to the variation of the PZT structure.
Hydrogen sorption mechanism of oxidized nickel clusters
Authors: Borgschulte A. , Westerwaal R. J. , Rector J. H. , Dam B. , Griessen R.
Published: November 2004

Using an optical technique to measure hydrogen sorption kinetics the catalytic activity of the NiOx clusters is determined. The thus measured temperature dependence reveals an activation energy of 0.58 eV. The catalytic activity of NiOx clusters is studied as a function of the oxygen concentration. The surface properties are analyzed by Auger-electron spectroscopy. It appears that the catalytic hydrogen sorption originates from the dissociative chemisorption of hydrogen on O:Ni, which is strongly suppressed by the presence of oxides.
Myocardial Performance Index with Sevoflurane–Pancuronium versus Fentanyl–Midazolam–Pancuronium in Infants with a Functional Single Ventricle
Authors: Ikemba Catherine M. , Su Jason T. , Stayer Stephen A. , Miller-Hance Wanda C. , Eidem Benjamin W. , Bezold Louis I. , Hall Stuart R. , Havemann Luke M. , Andropoulos Dean B.
Published: November 2004

Background

Patients with congenital heart disease characterized by a functional single ventricle make up an increasing number of patients presenting for cardiac or noncardiac surgery. Conventional echocardiographic methods to measure left ventricular function, i.e., ejection fraction, are invalid in these patients because of altered ventricular geometry. Two recently described Doppler echocardiographic modalities, the myocardial performance index and Doppler tissue imaging, can be applied to single-ventricle patients because they are independent of ventricular geometry. This study assessed the changes in myocardial performance index and Doppler tissue imaging in response to two anesthetic regimens, fentanyl-midazolam-pancuronium and sevoflurane-pancuronium.

Methods

Thirty patients aged 4-12 months with a functional single ventricle were randomized to receive fentanyl-midazolam or sevoflurane. Myocardial performance index and Doppler tissue imaging were measured by transthoracic echocardiography at baseline and two clinically relevant dose levels.

Results

Sixteen patients receiving sevoflurane and 14 receiving fentanyl-midazolam were studied. Myocardial performance index was unchanged from baseline with either agent (fentanyl-midazolam: 0.50 +/- 15 baseline vs. 0.51 +/- 0.15 at dose 2; sevoflurane: 0.42 +/- 0.14 baseline vs. 0.46 +/- 0.09 at dose 2). Doppler tissue imaging S (systolic)- and E (early diastolic)-wave velocities in the lateral ventricular walls at the level of the atrioventricular valve annulus were unchanged in the sevoflurane group; however, both Doppler tissue imaging S- and E-wave velocities were decreased significantly from baseline at dose 1 and dose 2 with fentanyl-midazolam, consistent with decreased longitudinal systolic and diastolic ventricular function.

Conclusions

Myocardial performance index, a global measurement of combined systolic and diastolic ventricular function, is not affected by commonly used doses of fentanyl-midazolam or sevoflurane in infants with a functional single ventricle.
Probenecid Interacts with the Pharmacokinetics of Morphine-6-glucuronide in Humans
Authors: Skarke Carsten , Langer Michael , Jarrar Marwan , Schmidt Helmut , Geisslinger Gerd , Lötsch Jörn
Published: November 2004

Background

Evidence obtained from porcine cell cultures and experiments in laboratory animals indicates that transmembrane transporters may play a role in the distribution of the active morphine metabolite morphine-6-glucuronide (M6G). This was evaluated in a study in healthy volunteers.

Methods

Ten subjects received an intravenous M6G infusion for 30 min at a dosage of 0.5 mg/kg body weight, leading to M6G plasma concentrations approximately two to three times higher than those observed with analgesic morphine doses in subjects with normal kidney function. In a randomized, double-blind, three-way crossover fashion, subjects received 800 mg quinidine for inhibition of P-glycoprotein; 500 mg probenecid for inhibition of other transporters, including organic anion transporter peptide, multidrug resistance-related protein, and organic anion transporter families; or placebo 1 h before the start of M6G administration. Plasma concentrations of M6G and pupil size were measured for 7 h.

Results

Probenecid pretreatment resulted in a decrease in the clearance of M6G from 8.3 +/- 1 l/h to 6.7 +/- 1.3 l/h (factor of 0.8; P < 0.05 vs. placebo cotreatment). This was paralleled by an increase by a factor of 1.2 of the area under the miotic effect-versus-time curves (P < 0.05 vs. placebo). In contrast, quinidine pretreatment had no influence on the pharmacokinetics of M6G.

Conclusions

The active morphine metabolite is subject to transmembrane transport by transporters inhibited by probenecid in humans.
Efficacy of a Prophylactic Epidural Blood Patch in Preventing Post Dural Puncture Headache in Parturients after Inadvertent Dural Puncture
Authors: Scavone Barbara M. , Wong Cynthia A. , Sullivan John T. , Yaghmour Edward , Sherwani Saadia S. , McCarthy Robert J.
Published: November 2004

Background

Postdural puncture headache (PDPH) occurs in up to 80% of parturients who experience inadvertent dural puncture during epidural catheter placement. The authors performed a randomized double blind study to assess the effect of prophylactic epidural blood patch on the incidence of PDPH and the need for therapeutic epidural blood patch.

Methods

Sixty-four parturients who incurred inadvertent dural puncture were randomized to receive a prophylactic epidural blood patch with 20 ml autologous blood (prophylactic epidural blood patch group) or a sham patch (sham group). Subjects were evaluated daily for development of PDPH for a minimum of 5 days after dural puncture. Those who developed a PDPH were followed daily for a minimum of 3 days after resolution of the headache. Subjects with moderate headaches who reported difficulties performing childcare activities and all those with severe headaches were advised to receive a therapeutic epidural blood patch.

Results

Eighteen of 32 subjects in each group (56%) developed PDPH. Therapeutic blood patch was recommended in similar numbers of patients in each group. The groups had similar onset time of PDPH, median peak pain scores, and number of days spent unable to perform childcare activities as a result of postural headache. The median duration of PDPH, however, was shorter in the prophylactic epidural blood patch group.

Conclusions

A decrease in the incidence of PDPH or the need for criteria-directed therapeutic epidural patch was not detected when a prophylactic epidural blood patch was administered to parturients after inadvertent dural puncture. However, prophylactic epidural blood patch did shorten the duration of PDPH symptoms.
Sweatshops: the theory of the firm revisited
Authors: Dessing Maryke
Published: November 2004

When the labor supply schedule is bending forward at low wage levels, the average cost curve of firms does the same. This leads to the possibility of multiple equilibria, in particular for monopolists, thereby opening a broader range of options and keeping non‐profitable firms in business. However, the global maximum is always occuring along the negatively sloping segment of the labor supply. Therefore, total welfare is declining, except perhaps in the case of monopolists, when firms are pursuing a low‐wage strategy to expand output and profits, and are exploiting labor's subsistence needs to pay wages below the marginal product.
PHOSPHOENOLPYRUVATE CARBOXYKINASE ACTIVITY IN ASCOPHYLLUM NODOSUM (PHAEOPHYCEAE)1
Authors: Kerby Nigel W. , Evans Leonard V.
Published: November 2004

PEP‐dependent4 CO2‐fixation by extracts of Ascophyllum nodosum (L.) Le Jol. is reported. The carboxylation of PEP is Mn2+ dependent and ATP is shown to be a product. IDP was found to be less efficient as a phosphate acceptor than ADP and 3‐mercaptopicolinic acid inhibited the carboxylation reaction. Extracts decarboxylated OAA only in the presence of ATP and had high activities of MDH and GOT. This evidence, together with the probable absence of PEPC, PEPCTrP, and PC in A. nodosum extracts, favors the view that PEPCK is responsible for the light‐independent CO2‐fixation observed in this alga.
SHORT‐TERM STANDING CROP AND DIVERSITY OF PERIPHYTIC DIATOMS IN A EUTROPHIC RESERVOIR1
Authors: Hoagland Kyle D.
Published: November 2004

Adverse weather and resultant turbulence caused sloughing of attached diatom communities during the first two weeks of colonization on artificial substrates. In contrast to Pacific macroalgal systems, older communities (8–12 d) were the most affected by wave action. Ash‐free dry weight of the periphyton and diatom cell density generally increased, except following periods of high turbulence when losses of up to 80% occurred. The maximum cell density (4 × 105 diatoms · cm−2) and ash‐free dry weight (2.9 mg · cm−2) are among the highest reported for similar conditions. Percent transmittance through the growth layer correlated significantly with cell density and ash‐free dry weight and is recommended as a rapid method for measuring the relative accumulation of periphyton. Diatom diversity generally increased throughout the study period and did not clearly reflect the effects of disturbance as did standing crop. Comparisons of diatom diversity and community composition indicated that the three overlapping growth series were not significantly different and samples collected on the same date were not more similar than those of identical age. Combined with previous evidence, the present study indicates that the first two weeks of substrate exposure in the summer represented a colonization phase followed by rapid microsuccession.
EFFECT OF COPPER ON GROWTH, SILICIC ACID UPTAKE AND SOLUBLE POOLS OF SILICIC ACID IN THE MARINE DIATOM, THALASSIOSIRA WEISFLOGII (BACILLARIOPHYCEAE)1
Authors: Rueter John G.
Published: November 2004

The toxicity of Cu to Thalassiosira weissflogii (Grunow) was investigated, focusing on the internal soluble pool of silicic acid. Silicic acid uptake and growth rates were found to be functions of both the cupric ion activity and the concentration of silicic acid in the growth medium. The soluble pool of Si per cell depended on the balance between the uptake rate and the division rate. The soluble pool in non‐dividing cultures reflected simply the uptake rate (and inhibition by copper of the uptake rate), but in dividing cultures the soluble pools had complex patterns with time depending on uptake rates and timing of division. Intracellular soluble pools of silicic acid are a good indicator for the relative inhibition of uptake and growth processes.