bluuebunny/crossref_metadata_2025 huggingface dataset:
Complexes of lysozyme with sodium (sulfamate‐carboxylate)isoprene/ethylene oxide double hydrophilic block copolymers
Authors: Pispas Stergios
Published: December 2006

Complexes between sodium (sulfamate‐carboxylate)isoprene/ethylene oxide double hydrophilic block copolymers and lysozyme, a globular protein, were formed in aqueous solutions, at pH 7, because of electrostatic interactions between the anionic groups of the polyelectrolyte block of the copolymers and the cationic groups of lysozyme. The structure of the complexes was investigated as a function of the anionic/cationic charge ratio of the two components in solution and ionic strength by static, dynamic, and electrophoretic light scattering, atomic force microscopy, and fluorescence spectroscopy. The mass and size of the micellar‐like complexes depend on the mixing ratio and the molecular characteristics (molecular weight, composition, and architecture) of the copolymer used. Complexation persists at 0.15M NaCl, the value for physiological saline, as a result of additional hydrophobic interactions between the copolymers and the enzyme. Fluorescence spectroscopy measurements indicate that the secondary structure of lysozyme does not change substantially after complex formation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 509–520, 2007
Enzyme–substrate interactions revealed by the crystal structures of the archaeal Sulfolobus PTP‐fold phosphatase and its phosphopeptide complexes
Authors: Chu Hsing‐Mao , Wang Andrew H.‐J.
Published: December 2006

The P‐loop‐containing protein phos‐phatases are important regulators in signal transduction. These enzymes have structural and functional similarity with a conserved sequence of Dx(25–41)HCxxGxxR(T/S) essential for catalysis. The singular protein tyrosine phosphatase (PTP) from archaeal Sulfolobus solfataricus is one of the smallest known PTPs with extreme thermostability. Here, we report the crystal structure of this phosphatase and its complexes with two tyrosyl phosphopeptides A‐(p)Y‐R and N‐K‐(p)Y‐G‐N. The structure suggests the minimal structural motif of the PTP family, having two variable sequences inserted between the β2–β3 and β3–β4 strands, respectively. The phosphate of both phosphopeptide substrates is bound to the P‐loop through several hydrogen bonds. Comparison of several phosphatase–substrate complexes revealed that Gln135 on the Q‐loop has different modes of recognition toward phosphopeptides. The substrate specificity of SsoPTP is primarily localized at the phosphotyrosine, suggesting that this phosphatase may be a prototypical PTP. Proteins 2007. © 2006 Wiley‐Liss, Inc.
A simple and rapid confirmatory assay for analyzing antibiotic residues of the macrolide class and lincomycin in bovine milk and yoghurt: hot water extraction followed by liquid chromatography/tandem mass spectrometry
Authors: Bogialli Sara , Di Corcia Antonio , Laganà Aldo , Mastrantoni Veronica , Sergi Manuel
Published: December 2006

A rapid and simple sample preparation procedure for determining residues of antibiotics of the class of macrolides and lincomycin in whole milk and yoghurt by liquid chromatography/tandem mass spectrometry (LC/MS/MS) is presented. The method is based on the matrix solid‐phase dispersion (MSPD) technique with hot water as extractant. After dispersing samples of milk and yoghurt on sand, target compounds were eluted from the MSPD column by passing through it 5 mL of water acidified with 30 mmol/L formic acid and heated at 70°C. After pH adjustment and filtration, a volume of 200 µL of the aqueous extract was directly injected into the LC column. MS data acquisition was generally performed in the multiple reaction monitoring (MRM) mode, selecting two precursor ion to product ion transitions for each target compound. Hot water appeared to be an efficient extracting medium, since absolute recoveries of the analytes in milk and yoghurt were respectively 68–86% and 82–96%. The method proved to be robust as matrix effects, even though present, did not affect significantly the accuracy of the method, as evidenced by analyzing six different batches of both milk and yoghurt. Using roxithromycin (a macrolide antibiotic not used in veterinary medicine) as surrogate internal standard, the accuracy of the method at three different spike levels of the analytes in milk and yoghurt was 86–107% (RSDs not larger than 10%) and 97–117% (RSDs not larger than 13%), respectively. On the basis of a signal‐to‐noise ratio of 10, we estimated this method can quantify a few ppb of the analytes in milk and yoghurt. These concentrations are well below the tolerance levels of macrolides and lincomycin in milk set by both the European Union and the US Food and Drug Administration. On analyzing six yoghurt samples, we found evidence for the fact that one of the six samples was contaminated with erythromycin B. Copyright © 2006 John Wiley & Sons, Ltd.
Glycerolysis of Fatty Acid Methyl Esters: 2. Simulation and Experiments in Continuous Reactors
Authors: Negi Devender S. , Kimmel Tobias , Wozny Günter , Schomäcker Reinhard
Published: December 2006

The glycerolysis of methyl ester was investigated in flow reactors. This reaction represents a liquid two‐phase reaction with changing reaction rates in a batch reactor. A semi‐empirical model tested earlier with batch reactor data was used to simulate different continuous processes for this reaction. Among the processes simulated, a single continuous‐flow stirred tank reactor (CSTR) without recycling was considered most appropriate for experimental implementation, although simulations showed that a faster reaction rate is possible with the application of a CSTR followed by a tubular reactor with certain associated residence times. The CSTR simulations were verified experimentally. A good agreement was found between the experimental data and simulation results.
RBMX is a novel hepatic transcriptional regulator of SREBP‐1c gene response to high‐fructose diet
Authors: Takemoto Tadashi , Nishio Yoshihiko , Sekine Osamu , Ikeuchi Chikako , Nagai Yoshio , Maeno Yasuhiro , Maegawa Hiroshi , Kimura Hiroshi , Kashiwagi Atsunori
Published: December 2006

In rodents a high‐fructose diet induces metabolic derangements similar to those in metabolic syndrome. Previously we suggested that in mouse liver an unidentified nuclear protein binding to the sterol regulatory element (SRE)‐binding protein‐1c (SREBP‐1c) promoter region plays a key role for the response to high‐fructose diet. Here, using MALDI‐TOF MASS technique, we identified an X‐chromosome‐linked RNA binding motif protein (RBMX) as a new candidate molecule. In electrophoretic mobility shift assay, anti‐RBMX antibody displaced the bands induced by fructose‐feeding. Overexpression or suppression of RBMX on rat hepatoma cells regulated the SREBP‐1c promoter activity. RBMX may control SREBP‐1c expression in mouse liver in response to high‐fructose diet.
Danggui Buxue Tang – A Chinese herbal decoction activates the phosphorylations of extracellular signal‐regulated kinase and estrogen receptor α in cultured MCF‐7 cells
Authors: Gao Qiu T. , Choi Roy C.Y. , Cheung Anna W.H. , Zhu Judy T.T. , Li Jun , Chu Glanice K.Y. , Duan Ran , Cheung Jerry K.H. , Jiang Zhi Y. , Dong Xiao B. , Zhao Kui J. , Dong Tina T.X. , Tsim Karl W.K.
Published: December 2006

Danggui Buxue Tang (DBT), a Chinese herbal decoction used to treat ailments in women, contains Radix Astragali (Huangqi; RA) and Radix Angelicae Sinensis (Danggui; RAS). The weight ratio of RA to RAS used in DBT must be 5:1 as stipulated as early as AD 1247; however, DBT's mechanism of action has never been described. Here, the estrogenic effects of DBT were investigated by determining the phosphorylations of estrogen receptor α (ERα) and extracellular signal‐regulated kinase 1/2 (Erk1/2) in cultured MCF‐7 cells. The application of DBT triggered the phosphorylation of ERα and Erk1/2 in a time‐dependent manner. In contrast to the effect of estrogen, DBT triggered ERα phosphorylation at both S118 and S167. This DBT‐specific phosphorylation was not triggered by an extract of one of the individual herbs, or by mixing the extracts of RA and RAS. DBT‐induced downstream signals are described here. These signals suggest the uniqueness of this Chinese herbal decoction that requires a well‐defined formulation.
High-Throughput Sample Preparation from Whole Blood for Gene Expression Analysis
Authors: Fang Xingwang , Evans Kurt , Willis Roy C. , Burrell Angela , Hoang Quoc , Xu Weiwei , Bounpheng Mangkey , Moturi Sharmili
Published: December 2006

Whole blood is an attractive sample source for nucleic acid-based assays because it is readily available, easily accessible, and rich in genetic information. However, globin mRNA accounts for up to 70% of the mRNA (by mass) in whole blood total RNA, resulting in distortion of the RNA amplification and subsequently causing decreased Present calls, decreased call concordance, and increased signal variation in microarray analysis. Therefore, for gene expression analysis, whole blood is typically fractionated before total RNA isolation to reduce globin mRNA content. We have developed a high-throughput sample preparation technology that streamlines workflows for (1) total RNA isolation from whole blood (MagMAX-96 Blood RNA Isolation Kit), (2) globin mRNA removal using a novel, nonenzymatic technology (GLOBINclear—Human Kit), and (3) mRNA amplification and labeling for expression analysis (MessageAmp II-96 aRNA Amplification Kit). Globin mRNA removal eliminates the need for prefractionation of whole blood, minimizing the potential for expression profile changes during sample handling. Quantitative RT-PCR showed that this method effectively removed up to 95% of the globin mRNA from the isolated RNA while retaining normal levels of other mRNAs. The streamlined sample preparation enables quick and accurate expression analysis of relatively high numbers of blood samples.
Nation, Empire, Globe: The Spaces of Population Debate in the Interwar Years
Authors: Bashford Alison
Published: December 2006

There are several analytical strands through which historians and demographers understand the evolution of twentieth-century population politics and expertise. One is the history of the declining birthrate, nationalism, pro-natalism, and modern degeneration anxieties, including histories of eugenics. A second strand is the story of global overpopulation, its mobilization as a mid-twentieth-century issue in Cold War politics, the dominance of the idea of demographic transitions and political economy, and subsequent links between aid, development, family planning, and various international agencies. A third is the history of reproductive and bodily rights, feminism, and birth control, which has been analyzed with respect to the history of technology, the history of colonialism and neo-colonialism, the history of nationalism, and to some extent the history of internationalism. The political economy aspects of the population question tend chronologically to bookend the feminist narrative, with Malthus at the late eighteenth-century end and Cold War political economy of third world development at the twentieth-century end. A fourth strand is a burgeoning intellectual history of demography, social science, and economic theory.
Age estimates and description of rhodoliths from Esperance Bay, Western Australia
Authors: Goldberg Nisse
Published: December 2006

Rhodoliths were collected in Esperance Bay,Western Australia, using a Van Veen grab from a bed that covered an area approximately 2.2 km2, in depths of 38 ±1 m. Rhodolith abundance (biomass per 0.1 m3), mean size (maximum diameter), and morphotypes were compared among the inshore margin, offshore margin, and middle area of the bed. Accelerator Mass Spectrometry was used to estimate ages of five free-living rhodoliths. Rhodolith taxa included Hydrolithon munitum, Lithothamnion sp., an unidentified Melobesiodeae (a Mesophyllum or Synarthrophyton) and possibly a species of Sporolithon, with lumpy, warty, and fruticose morphologies. The middle area of the bed had significantly greater abundance of rhodoliths than either margin. Biomass of warty rhodoliths was greater in the middle area of the bed whereas fruticose and lumpy rhodoliths had similar biomass across the bed. The <20 mm size-class was the most abundant and these rhodoliths may originate from fragmentation of larger individuals. Radiocarbon age estimates ranged between calibrated ages of AD1050 and modern, indicating that a proportion of living rhodoliths consisted of fossil rhodoliths that had been recolonized. The combination of coastal morphology, gently-sloping sea-floor, hydrodynamics, and rhodolith morphology was representative of rhodolith beds found elsewhere in the world.
Larval and postlarval development of Pagurus nigrofascia (Decapoda: Anomura: Paguridae) reared in the laboratory
Authors: Oba Takashi , Konishi Kooichi , Goshima Seiji
Published: December 2006

Zoeal, megalopal and first crab stages of Pagurus nigrofascia are described and illustrated from laboratory reared specimens. Larvae were reared at temperatures 6°C, 12°C, 18°C, and 25°C. Survival rates of larvae were considerably higher at 12°C and 18°C, but were low at 6°C and 25°C. Larvae and postlarvae of P. nigrofascia can be distinguished from seven morphologically similar species based on adult or larval morphological features. Zoeal stages of this species are distinguished by, for example, setal formulae of maxillule, maxilla and maxilliped 1. The megalopal stage can be identified by the telsonal process, the number of articles of the flagellum of antenna and setal formula on the scaphognathite of the maxilla. Morphological features of P. nigrofascia larvae are similar to those of P. ochotensis, P. kennerlyi and P. pectinatus.
Tree-climbing behaviour of Cerithidea decollata, a western Indian Ocean mangrove gastropod (Mollusca: Potamididae)
Authors: Vannini Marco , Rorandelli Rocco , Lähteenoja Outi , Mrabu Elisha , Fratini Sara
Published: December 2006

The behaviour of Cerithidea decollata, a common western Indian Ocean mangrove tree climbing gastropod, was studied in Mida Creek, Kenya. At the study site, this snail mainly lived in Avicennia marina dominated areas, i.e. in the mangrove belt between high water spring tide and high water neap tide levels. Not a single individual was found on the less common mangrove tree Lumnitzera racemosa, living just above the A. marina level (together with terrestrial grass), and was very rarely recorded on the common Rhizophora mucronata, bordering the seaward side of the A. marina belt. No significant gradient of C. decollata density was found within the whole 150–200 m wide belt. The majority of C. decollata rested on tree trunks during high tide, creeping on the mud flat below the tree for part of low tide, and returning on the trunks well before being reached by the water. This migratory pattern was more evident at spring than at neap tide, at day than at night time and it was strongly influenced by the shore level of the mangrove zone in which animals resided. While C. decollata from lower shore levels neatly massively migrated twice a day, individuals from upper levels showed a more continuous and irregular activity, sometimes crawling on the mud even at high water of spring tide, when they experience just a few centimetres of water for no more than one to two hours.
Desseria zei sp. nov. (Adeleorina: Haemogregarinidae) infecting Zeus capensis from deep waters off the south and west coasts of South Africa
Authors: Smit N.J. , Davies A.J.
Published: December 2006

Blood films from a marine fish, the Cape Dory (Zeus capensis), trawled at depths between 149 and 389 m off the south and west coasts of South Africa, contained a new species of haemogregarine, Desseria zei sp. nov. The apicomplexan, found in 25/97 fish from the two regions, was generally intra-erythrocytic. Parasitaemia was usually low, but attained infection levels of 1/10 erythrocytes in one fish. The parasite stages were all gamonts and monomorphic, but likely varied in maturity; they were 3.3–4.5 μm wide by 14.7–18.3 μm long, curved with bluntly pointed ends, and existed singly within erythrocytes, or in pairs in the heavy infection. Their cytoplasm was deep blue, granular, and stained deeply at the anterior and sometimes, posterior extremities. Two or three vacuoles occurred in the cytoplasm between the anterior cap and the gamont nucleus, which was positioned in the posterior third of the parasite body. Gamonts lay close to the host cell nucleus, often curved around it. Distortion of host cells and host nucleus displacement occurred when single gamonts curved away from the host nucleus, or if they were paired. A few extracellular gamonts were observed, occasionally associated with the remnants of the erythrocyte nucleus.
Mapping and Survey of Plasma Bubbles over Brazilian Territory
Authors: de Rezende L. F. C. , de Paula E. R. , Kantor I. J. , Kintner P. M.
Published: December 2006

Ionospheric plasma irregularities or bubbles, that are regions with depleted density, are generated at the magnetic equator after sunset due to plasma instabilities, and as they move upward they map along the magnetic field lines to low latitudes. To analyse the temporal and spatial evolution of the bubbles over Brazilian territory, the mapping of ionospheric plasma bubbles for the night of 17/18 March 2002 was generated using data collected from one GPS receiver array, and applying interpolation techniques. The impact on the performance of Global Navigation Satellites System (GNSS) and on the Space Based Augmentation System (SBAS) in the tropical regions of the GPS signal losses of lock and of the signal amplitude fades during ionospheric irregularities is presented.
Illuminant and observer metamerism and the Hardy-Rand-Rittler color vision test editions
Authors: DAIN STEPHEN J.
Published: December 2006

A previous study identified a significant metamerism in the several editions of the Hardy-Rand-Rittler pseudoisochromatic plates (HRR) but did not proceed to quantify the consequences of that metamerism (Dain, 2004). Metamerism arises from two sources and is almost inevitable when a printed color vision test is reproduced in several editions. Metamerism has two consequences; these are illuminant/source-based changes in performance and changes in performance with observer (less well known) when assessing anomalous trichromats. This study addresses the effects of illuminant/source and observer metamerism on the fourth editions of the HRR. Groups of colors intended to lie on a dichromat confusion line generally remain on a confusion line when the source is changed. The plates appear to be resistant to each form of metamerism, perhaps because the features of the spectral reflectance are similar for figure color and background gray. As a consequence, the clinician needs to be less concerned about using a non-recommended source than was previously believed.
Spearman's Law of Diminishing Returns
Authors: Hartmann Peter
Published: December 2006

Spearman's Law of Diminishing Returns (SLODR) with regard to age was tested in two different databases from the National Longitudinal Survey of Youth. The first database consisted of 6,980 boys and girls aged 12–16 from the 1997 cohort ( NLSY 1997 ). The subjects were tested with a computer-administered adaptive format (CAT) of the Armed Services Vocational Aptitude Battery (ASVAB) consisting of 12 subtests. The second database consisted of 11,448 male and female subjects aged 15–24 from the 1979 cohort ( NLSY 1979 ). These subjects were tested with the older 10-subtest version of the ASVAB. The hypothesis was tested by dividing the sample into Young and Old age groups while keeping IQ fairly constant by a method similar to the one developed and employed by Deary et al. (1996) . The different age groups were subsequently factor-analyzed separately. The eigenvalue of the first principal component (PC1) and the first principal axis factor (PAF1), and the average intercorrelation of the subtests were used as estimates of the g saturation and compared across groups. There were no significant differences in the g saturation across age groups for any of the two samples, thereby pointing to no support for this aspect of Spearman's “Law of Diminishing Returns.”
Effect of enriched early dropped rainwater on mesoscale isotopic distribution in surface water on the Kii Peninsula, Japan
Authors: Ishizuka Masahide , Sone Yumi , Ii Hiroyuki , Hirata Tatemasa
Published: December 2006

Mesoscale spatial distributions and temporal variations of oxygen and hydrogen isotope compositions in surface waters were observed on the Kii Peninsula, Japan, which receives more than 3000 mm of precipitation annually. The enriched isotopic values were distributed along the western, southern, and eastern coasts. To explain this, we proposed a new parameter, early dropped rainwater frequency (ERF), and defined it as the number of times that early dropped rainwater was first observed in a domain. ERF can be considered a characteristic of rainfall, and it is a useful parameter for clarifying mesoscale isotopic distribution. A mass balance simulation suggested the early dropped rainwater determined the specific isotopic value of stream water in a watershed.
In situ measurement of thermal electrons on the SIERRA nightside auroral sounding rocket
Authors: MacDonald E. A. , Lynch K. A. , Widholm M. , Arnoldy R. , Kintner P. M. , Klatt E. M. , Samara M. , LaBelle J. , Lapenta G.
Published: December 2006

In January 2002 the SIERRA sounding rocket was launched from Alaska into active substorm expansion aurora. Direct measurements of the cold ionospheric population in darkness were made by the Thermal Electron Detector (TED), which was designed to measure thermal electrons that can carry auroral currents coupling the lower ionosphere and the magnetosphere. Measurement of thermal electrons must be accompanied by a careful study of electrostatic potentials forming near conducting bodies in a plasma. The TED instrument measurements show that a nonmonotonic potential barrier can form in the sheath around the attractively biased detector and prevent measurements of the core of the thermal electrons. The TED instrument design and response are discussed along with the current balance conditions which can lead to the formation of a potential barrier. A plasma distribution reconstruction technique enables key measurements of temperature, density, spacecraft potential, and an estimate of field‐aligned current flow. Observed thermal electron core temperatures vary greatly, from ∼0.1 eV in the polar cap to ∼0.8 eV in auroral arcs. Outside active precipitation, the electron density agrees with an independent calculation based on measurements from the high‐frequency (HF) wave receiver, verifying the method used for estimating the spacecraft potential. In the auroral regions the HF measurement of electron plasma density must be used to extract more accurate results for the spacecraft potential. The thermal electron data indicate that in the dark the nonnegligible auroral and secondary emission currents must be accounted for in order to understand the spacecraft potential and its impact on thermal electron measurements.
Variations in the midlatitude and equatorial ionosphere during the October 2003 magnetic storm
Authors: Garner T. W. , Bust G. S. , Gaussiran T. L. , Straus P. R.
Published: December 2006

The October 2003 geomagnetic storm (often called the Halloween storm) was one of the largest storms (as measured by Dst) yet recorded. The storm‐induced synoptic‐scale changes in the ionosphere's plasma content and density can be viewed through space weather maps created by objective analysis algorithms. For this study, these maps, which specify the electron density in altitude, latitude, and longitude, are created by the ionospheric data assimilation three dimensional (IDA3D), a three‐dimensional variation algorithm of the ionospheric electron density. These maps, representing the average conditions in the ionosphere over a 15 min sampling time, show how dramatically the ionosphere changed during the Halloween storm. Following the southward turning of the interplanetary magnetic field, the dayside electron content is significantly reduced in the equatorial ionosphere between ±18° magnetic latitude and is enhanced poleward of this latitude. This is the expected behavior when the equatorial fountain is enhanced by a strong penetration electric field. In addition, the electron content is significantly increased in the dayside midlatitude ionosphere, which corresponds to a storm‐enhanced density (SED) plume. Above 40° magnetic latitude, the dayside plasma content is significantly reduced in the regions adjacent to the SED structure, which enhances the electron content gradient. Electron density maps in the altitude–magnetic latitude plane show an increase in the topside electron densities within an SED plume.
Changes of anthropogenic CO2 and CFCs in the North Atlantic between 1981 and 2004
Authors: Tanhua Toste , Biastoch Arne , Körtzinger Arne , Lüger Heike , Böning Claus , Wallace Douglas W. R.
Published: December 2006

We compare total dissolved inorganic carbon (DIC) and chlorofluorocarbon (CFC) measurements in the northwest Atlantic made during the Transient Tracers in the Ocean, North Atlantic Study (TTO‐NAS) in 1981 with modern measurements from a cruise in 2004. The observed changes in the DIC and CFC fields are compared to those predicted from an eddy‐permitting ocean circulation model. The rapid, but time‐variable, atmospheric CFC increase in relation to the relatively steady anthropogenic CO2 increase influences the relationship between the observed uptake of DIC and CFC. We demonstrate the importance of ocean mixing in the calculation of anthropogenic CO2 (Cant) based on transient tracer data by comparing our observations to a “no‐mixing” scenario. We further find that the Cant is in transient steady state in the North Atlantic; that is, the Cant concentration increases proportionally over time through the whole water column in a manner that is directly related to the time‐dependent surface concentration.
Deep water mass geometry in the glacial Atlantic Ocean: A review of constraints from the paleonutrient proxy Cd/Ca
Authors: Marchitto Thomas M. , Broecker Wallace S.
Published: December 2006

Paleonutrient proxies currently provide the strongest constraints on the past spatial distribution of deep water masses. We review the state of knowledge derived from the trace metal proxy Cd/Ca for the Atlantic Ocean during the Last Glacial Maximum (LGM). We compile published benthic foraminiferal Cd/Ca data, supplemented with new data, to reconstruct meridional Cd sections through the Holocene and LGM Atlantic. Holocene Cd/Ca reflects the modern water masses North Atlantic Deep Water (NADW), Antarctic Bottom Water (AABW), and Antarctic Intermediate Water (AAIW) reasonably well, except for anomalously high values in the intermediate to mid‐depth far North Atlantic. LGM Cd/Ca clearly shows that NADW was replaced by the shallower Glacial North Atlantic Intermediate Water (GNAIW), with significant northward expansion of AABW. The boundary level between GNAIW and AABW was very abrupt, occurring between ∼2200 and 2500 m modern water depth. Combined Cd/Ca and Cibicidoidesδ13C data allow us to also calculate the air‐sea signature of δ13C (δ13Cas). The LGM Atlantic can be explained entirely by mixing between high‐δ13Cas GNAIW and low‐δ13Cas AABW. Negative δ13Cas values in glacial AABW were likely caused by poor ventilation during formation, probably associated with extensive sea ice coverage. Overall, our knowledge base would benefit from improved data coverage in the South Atlantic and Southern Ocean, and a better understanding of ancillary effects on the Cd/Ca proxy itself.
On the stability of the Earth's radiative energy balance: Response to the Mt. Pinatubo eruption
Authors: Harries J. E. , Futyan J. M.
Published: December 2006

A volcanic eruption provides a natural experiment in which time constants for the onset and decay of the consequent radiative perturbation may be measured. The radiative and atmospheric responses also provide insight into how the top of atmosphere net balance of energy responds to perturbations. We analyse the response of the atmospheric humidity, temperature and radiative fields to the eruption of Mt Pinatubo to determine time constants for the growth and the decay of perturbations in these fields. We are able to distinguish between processes that respond directly to the insertion of aerosols into the atmosphere, and those, such as changes in the humidity and temperature, that involve slower dynamical processes and therefore have longer response times. The physical basis for these observations is discussed, and it is suggested that a valuable test of coupled climate models should be that they reproduce these response times, and the associated flux anomalies.
Long‐term observations of stratospheric bromine reveal slow down in growth
Authors: Dorf M. , Butler J. H. , Butz A. , Camy‐Peyret C. , Chipperfield M. P. , Kritten L. , Montzka S. A. , Simmes B. , Weidner F. , Pfeilsticker K.
Published: December 2006

The total stratospheric inorganic bromine burden (Bry) was derived from balloon‐borne bromine monoxide (BrO) observations performed with the LPMA/DOAS (Limb Profile Monitor of the Atmosphere/Differential Optical Absorption Spectroscopy) balloon payload in the last ten years. The measurements show that significantly more ozone‐depleting bromine ((4.1[or 4.3] ± 2.5) ppt) reaches the stratosphere than the atmospheric transport of the major stratospheric bromine source gases, methyl bromide (CH3Br) and all halons can account for. The major contributors to this discrepancy are varying amounts of bromine tied in inorganic gases, particulate matter and very short‐lived substances (VSLS) of natural origin. Despite the significant contribution of stratospheric bromine from natural processes, international protocols introduced to limit the production of brominated gases have been effective by slowing down the overall growth of Bry.
Role of turbines in the carbon dioxide emissions from two boreal reservoirs, Québec, Canada
Authors: Roehm Charlotte , Tremblay Alain
Published: December 2006

The potential for degassing of carbon dioxide stemming from the passage of water through turbines of hydroelectric reservoirs was studied in two boreal reservoirs (La Grande 2 and La Grande 3) located in the James Bay region of Québec, Canada. Samples of dissolved CO2 were taken monthly over a period of 1 year from the main reservoirs, within the hydroelectric facilities from the shaft entering the turbine system and from the exits below the facilities. Diffusive fluxes from the reservoir surfaces were calculated using the thin boundary layer equation. The differences between CO2 concentrations above and below the dams were used to calculate the amount of degassing per unit of water turbined. Diffusive flux calculations indicated that the reservoirs acted as sources of CO2 to the atmosphere throughout the sampling period, with fluxes ranging between 80 and 1800 mg CO2 m−2 d−1 at LG2 and between 400 and 1500 mg CO2 m−2 d−1 at LG3. Degassing calculated from turbining ranged between 5–45 and 5–25 t d−1 at LG2 and LG3, respectively, and represented between <1 and 7% and mean weighted values of <1% of the equivalent fluxes across the air‐water interface of the main reservoirs. The quantity of degassing is seasonally defined, with highest rates observed in the winter/spring period, a result of lower water temperature effects on the solubility of CO2, and the buildup of gases over the winter period due to mineralization of organic matter and the influx from watershed sources due to the springtime melt. Depending on the effluxes occurring at the air‐water interface of the main reservoir, degassing can represent a maximum equivalent 16%. This study indicates that the main role of turbining lies in the seasonality of release of GHG rather than the absolute amount.
Misleading patterns in correlation maps
Authors: Coughlin K. T. , Tung K. K.
Published: December 2006

We point out the pitfall of using spatial patterns of correlation coefficients obtained from filtered data to infer physical mechanisms. Filtering is often used to emphasize a signal of interest by removing unrelated variability, but it alters subsequent correlation maps when the removed variance contains spatial structure, as is most often the case in geophysical applications. This then results in misleading patterns of correlation. In the case where filtering involves the removal of independent signals, we show that the resulting increase in correlation is entirely due to the removed signal. We include a short discussion of alternative methods that can be used to generate more consistent maps of statistical relationships.
One Martian year of atmospheric observations using MER Mini‐TES
Authors: Smith Michael D. , Wolff Michael J. , Spanovich Nicole , Ghosh Amitabha , Banfield Don , Christensen Philip R. , Landis Geoffrey A. , Squyres Steven W.
Published: December 2006

The Spirit and Opportunity Mars Exploration Rovers (MER) landed on the surface of Mars in January 2004. Thermal infrared spectra taken by the Miniature Thermal Emission Spectrometer (Mini‐TES) instrument on board each rover, collected in both the upward‐looking and downward‐looking geometries, has allowed for the retrieval of atmospheric temperatures between 1 and 2000 m above the surface, the column optical depth of dust, and the column abundance of water vapor for more than one full Martian year. During this period, Mini‐TES has observed the annual cycle of temperature variations, the diurnal growth and decay of a near‐surface highly superadiabatic layer, and random temperature fluctuations on a timescale of less than a minute. Mini‐TES observations also record the timing, duration, and intensity of several local‐scale and regional‐scale dust storms and the annual variation of water vapor abundance at the two rover locations.
A model to predict cloud density from midlatitude atmospheric soundings for microwave radiative transfer applications
Authors: Pierdicca Nazzareno , Pulvirenti Luca , Marzano Frank S.
Published: December 2006

A new model for computing cloud liquid density from vertical profiles of meteorological variables, provided by either radio soundings or atmospheric analyses, is proposed. It has been developed for local‐scale applications, in particular for a midlatitude environment such as the Mediterranean area, although the methodology can be easily extended to other climatic zones. The model has been derived from a numerical simulation of a cloudy event that occurred in the Mediterranean basin, performed by means of a microphysical mesoscale meteorological simulation package. The validation has been mainly carried out through a comparison between brightness temperature simulations in cloudy conditions and satellite microwave radiometric data over the Mediterranean Sea. The simulations have been performed by applying a radiative transfer scheme to a set of atmospheric profiles consisting of both European Centre for Medium‐Range Weather Forecasts (ECMWF) analyses and radiosonde measurements. Two literature models have been considered as benchmarks. The new model reproduces the Special Sensor Microwave Imager brightness temperature statistics in the Mediterranean area fairly well. Furthermore, it predicts an integrated liquid water content which is in agreement with that supplied by the ECMWF analyses.
Public support for river restoration funding in relation to local river ecomorphology, population density, and mean income
Authors: Schläpfer Felix , Witzig Pieter‐Jan
Published: December 2006

In 1997, about 140,000 citizens in 388 voting districts in the Swiss canton of Bern passed a ballot initiative to allocate about 3 million Swiss Francs annually to a canton‐wide river restoration program. Using the municipal voting returns and a detailed georeferenced data set on the ecomorphological status of the rivers, we estimate models of voter support in relation to local river ecomorphology, population density, mean income, cultural background, and recent flood damage. Support of the initiative increased with increasing population density and tended to increase with increasing mean income, in spite of progressive taxation. Furthermore, we found evidence that public support increased with decreasing “naturalness” of local rivers. The model estimates may be cautiously used to predict the public acceptance of similar restoration programs in comparable regions. Moreover, the voting‐based insights into the distribution of river restoration benefits provide a useful starting point for debates about appropriate financing schemes.
Selection and characterization of an internalizing epidermal‐growth‐factor‐receptor antibody
Authors: Zhao Xiaorong , Dai Wentao , Cao Limin , Zhu Huifen , Yu Yihan , Ye Qing , Wang Min , Dai Wei , Lei Ping , Shen Guanxin
Published: December 2006

Antibody–therapeutic agent conjugates to be delivered directly into the cytosol of tumour cells is required for many target‐based therapeutic strategies. For this work, a large non‐immune phage‐display library was used to select internalizing scFv (single chain variable fragment) directed against EGFR (epidermal growth factor receptor), a tyrosine kinase receptor that is overexpressed in a wide range of tumour cells. The CHO‐EGFR‐GFP1 (where CHO is Chinese‐hamster ovary) cell line, a transfected cell line expressing EGFR–GFP (green fluorescent protein) fusion protein on membranes, and the untransfected cell line CHO‐K1 were used as EGFR‐positive cells and ‐negative cells respectively in the subtractive selection procedure. A novel human anti‐EGFR scFv (F4‐scFv) was isolated. F4‐scFv bound native EGFR‐bearing cell lines and could be internalized, but did not bind EGFR‐negative cell lines. The KD value of F4‐scFv was 472 nM as determined on A431 cells. F4‐scFv could be used to target therapeutic agents into tumour cells and was expected to be non‐immunogenic in humans. Use of a transfected cell line expressing GFP‐tagged receptors allows selection and characterization of antibodies to native receptors without the need for protein expression and purification, significantly speeding up the generation of targeting antibodies.
Copper deprivation in rats induces islet hyperplasia and hepatic metaplasia in the pancreas
Authors: Tosh David , Shen Chia‐Ning , Alison Malcolm R. , Sarraf Catherine E. , Slack Jonathan M.W.
Published: December 2006

Background information. Prolonged copper deprivation in rats followed by refeeding with a normal diet has previously been used to induce the appearance of hepatocyte‐like cells in the pancreas, but the effects on islet size and morphology have not been determined.

Results. In the present study we investigated the distribution of pancreatic α‐ and β‐cells and of hepatocytes in adult rats fed a copper‐deficient diet followed by refeeding with a normal diet. Immunohistochemical staining for insulin and glucagon showed that the islets of the copper‐deficient group were up to 2.4 times larger in mass compared with controls. The islets were disorganized, with α‐cells found in multiple layers at the periphery of the islet and sometimes deep in the core. Isolated α‐ and β‐cells were also found in increased numbers in the ductular system. Copper deprivation caused almost complete ablation of the acinar cells, and refeeding induced adipogenesis, acinar regeneration and hepatocyte‐like cells. Ductular proliferation and nerve hyperplasia were also present. The hepatocytes tended to be associated with islets or with ducts, rather than with residual pancreatic exocrine tissue.

Conclusions. These data show that copper deficiency in rats, as well as inducing the appearance of hepatocytes, is capable of causing islet hyperplasia.
Optical susceptibilities of supported indium tin oxide thin films
Authors: Humphrey Jonathan L. , Kuciauskas Darius
Published: December 2006

The third-order nonlinear optical susceptibility of indium tin oxide (ITO) thin films on glass substrates, χ(3)ITO, was determined in the near-IR spectral region using degenerate four wave mixing (DFWM) spectroscopy with 100fs laser pulses. A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100nm thick and applied to ∼25nm thick ITO films. It was found that χ(3)ITO is purely electronic at 900–1300nm (11000–7700cm−1) and has a value of (2.16±0.18)×10−18m2V−2. The χ(3)ITO value reaches (3.36±0.28)×10−18m2V−2 at 1500nm (6700cm−1) due to two-photon absorption by free carriers (electrons). Ultrafast electron relaxation was also observed. The ∼100fs lifetime of this process could reflect electron scattering in the conduction band.
Cobalt ferrite nanoparticles: Achieving the superparamagnetic limit by chemical reduction
Authors: Jeppson P. , Sailer R. , Jarabek E. , Sandstrom J. , Anderson B. , Bremer M. , Grier D. G. , Schulz D. L. , Caruso A. N. , Payne S. A. , Eames P. , Tondra Mark , He Hongshan , Chrisey D. B.
Published: December 2006

An unanticipated superparamagnetic response has been observed in cobalt ferrite materials after thermal treatment under inert atmosphere. Cobalt ferrite particles were prepared via normal micelle precipitation that typically yields CoxFe3−xO4 nanoparticles (x=0.6−1.0). While samples thermally treated under oxygen show majority spinel phase formation, annealing in nitrogen gas yields materials consisting of Co-Fe alloy, FeS, and CoFe2O4 spinel. After thermal treatment, thermomagnetic studies reveal composition-insensitive, but highly treatment-sensitive, saturation magnetization, coercivity, blocking temperature, and Verwey transition temperature dependence. Extremely high saturation magnetization (159 emu/g) with low coercivity (31 Oe) was observed for one of the treated compositions, which drastically deviates from prototypical cobalt ferrite with large magnetocrystalline anisotropy. We attribute such unique magnetic response to Co-Fe alloy coexisting with FeS and CoFe2O4 spinel where the diameter of the metallic phase is below the superparamagnetic limit. While thermal treatment in nitrogen was not anticipated to yield Co-Fe alloy, chemisorbed surfactant molecules (i.e., sodium dodecylsulfate) are postulated to act as reducing agents in the present scenario.
Field-emission properties of ultrathin 5nm tungsten nanowire
Authors: Yeong K. S. , Thong J. T. L.
Published: December 2006

We report the field-emission properties of ultrathin tungsten nanowires of 5nm diameter and several hundred nanometer length. Fowler-Nordheim plots of field-emission current-voltage measurements of such nanowires show marked deviation from linearity. After flashing, cold-field-emission current stability with standard deviation of better than 1% has been observed for periods of at least 30min at a vacuum level of 10−9mbar. Beyond this, field-emission current noise was found to mainly comprise current step jumps and current spikes. At high emission current densities in the order of 106Acm−2, the noise changes into flicker noise. Field emission at high current density induced surface diffusion and crystallization of the disordered nanowire tip due to temperature rise at the field-emitting tip. Further increase in the emission current density initiated local arc destruction which caused shortening of the nanowire length.
Experimental evidence of mode coupling in drift wave intermittent turbulence using a wave number bicoherence analysis
Authors: Brochard F. , Windisch T. , Grulke O. , Klinger T.
Published: December 2006

Spatiotemporal mode coupling is studied experimentally in a cylindrical plasma device. For that purpose, a bicoherence analysis is applied to spatially resolved measurements of drift wave fluctuations in order to study nonlinear coupling in the wave number spectrum. The use of the k bicoherence is shown to be much more accurate and straightforward than one of the ω bicoherence, revealing bicoherence bursts with a characteristic duration shorter than the characteristic period of the signals. It is demonstrated that intermittent structures can be produced during these events.
Intersubband transition in narrow GaInNAs∕GaAs quantum wells
Authors: Liu H. C. , Song C. Y. , Gupta J. A. , Aers G. C.
Published: December 2006

The authors report on experimental results of intersubband absorption in a set of Ga0.77In0.23N0.01As0.99∕GaAs quantum well structures with different well widths from 2.6to4.4nm. Due to the peculiar conduction band dispersion, the observed intersubband transition energy is quite insensitive to the well width for these narrow wells. The observed intersubband resonance positions are in good agreement with a model calculation.
Tsunami inundation modeling for western Sumatra
Authors: Borrero José C. , Sieh Kerry , Chlieh Mohamed , Synolakis Costas E.
Published: December 2006

A long section of the Sunda megathrust south of the great tsunamigenic earthquakes of 2004 and 2005 is well advanced in its seismic cycle and a plausible candidate for rupture in the next few decades. Our computations of tsunami propagation and inundation yield model flow depths and inundations consistent with sparse historical accounts for the last great earthquakes there, in 1797 and 1833. Numerical model results from plausible future ruptures produce flow depths of several meters and inundation up to several kilometers inland near the most populous coastal cities. Our models of historical and future tsunamis confirm a substantial exposure of coastal Sumatran communities to tsunami surges. Potential losses could be as great as those that occurred in Aceh in 2004.
Molecular identification of microsomal acyl-CoA:glycerol-3-phosphate acyltransferase, a key enzyme in
de novo
triacylglycerol synthesis
Authors: Cao Jingsong , Li Jian-Liang , Li Dongmei , Tobin James F. , Gimeno Ruth E.
Published: December 2006

Acyl-CoA:glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first step during
de novo
synthesis of triacylglycerol. It has been well recognized that mammals possess multiple enzymatically distinct proteins with GPAT activity. Although the mitochondrial-associated GPAT has been cloned and extensively characterized, the molecular identity of the endoplasmic reticulum (ER)-associated GPAT, which accounts for the majority of total GPAT activity in most tissues, has remained elusive. Here we report the identification of genes encoding human and mouse ER-associated GPAT (termed GPAT3). GPAT3 is a member of the acyltransferase family predominantly expressed in tissues characterized by active lipid metabolism, such as adipose tissue, small intestine, kidney, and heart. Ectopic expression of GPAT3 leads to a significant increase in
N
-ethylmaleimide-sensitive GPAT activity, whereas acyltransferase activity toward a variety of other lysophospholipids, as well as neutral lipid substrates, is not altered. Overexpression of GPAT3 in mammalian cells results in increased triacylglycerol, but not phospholipid, formation. GPAT3 is localized to the ER when overexpressed in COS-7 cells. GPAT3 mRNA is dramatically up-regulated during adipocyte differentiation, is reciprocally regulated in adipose tissue and liver of
ob/ob
mice, and is up-regulated in mice treated with a peroxisome proliferator-activated receptor γ (PPARγ) agonist. A substantial loss of GPAT activity in 3T3-L1 adipocytes was achieved by reducing GPAT3 mRNA levels through GPAT3-specific siRNA knockdown. These findings identify GPAT3 as a previously uncharacterized triacylglycerol biosynthetic enzyme. Similar to other lipogenic enzymes, GPAT3 may be useful as a target for the treatment of obesity.