bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Risk Factors for Perioperative Mortality in Acute Mesenteric Ischemia
Authors: Acosta‐Merida Maria Asuncion , Marchena‐Gomez Joaquin , Hemmersbach‐Miller Marion , Roque‐Castellano Cristina , Hernandez‐Romero Juan Maria
Published: July 2006

Introduction

Acute intestinal ischemia is in most cases a lethal condition with a low survival rate. Risk factors of perioperative mortality are poorly defined. The aim of this study was to define risk factors that predict an adverse outcome of acute mesenteric ischemia (AMI).

Methods

A total of 132 consecutive patients (73 men, 59 women), mean ± SD age 71.96 ± 13.64 years, who underwent surgery because of AMI in a university tertiary care center were evaluated over a period of 10 years. Clinical features, laboratory findings, etiologic factors, and surgical procedures were recorded and assessed as possible risk factors for perioperative mortality.

Results

Of 132 patients, 86 (65.2%) died during the perioperative period as a direct result of AMI. Significant univariate predictors of perioperative mortality were age (P = 0.01), cardiopathy (P = 0.002), digoxin intake (P = 0.015), shock (P = 0.01), urea plasma level (P < 0.001), creatinine (P < 0.001), potassium (P = 0.042), low pH (P = 0.015) and bicarbonate (P = 0.035); hemoglobin ≥ 2.48 mmol/L (P = 0.035); time delay to surgery (P = 0.023); colonic involvement (P < 0.001); small and large bowel involvement (P < 0.001); arterial versus venous ischemia (P = 0.007); and intestinal resection (P < 0.001). In the multivariate analysis, the variables previous cardiac illness (P = 0.045), urea plasma levels (P < 0.001), and small and large bowel involvement were identified as independent risk factors of perioperative mortality. Intestinal resection (P < 0.001) was a favorable predictor.

Conclusions

Age, time delay to surgery, shock, and acidosis significantly increase the risk of mortality due to AMI, whereas intestinal resection has a protective effect. However, only previous cardiac illness, acute renal failure, and large bowel ischemia have a negative effect as independent risk factors of mortality of AMI.
Lipidomics of host–pathogen interactions
Authors: Wenk Markus R.
Published: July 2006

The cell biology of intracellular pathogens (viruses, bacteria, eukaryotic parasites) has provided us with molecular information of host–pathogen interactions. As a result it is becoming increasingly evident that lipids play important roles at various stages of host–pathogen interactions. They act in first line recognition and host cell signaling during pathogen docking, invasion and intracellular trafficking. Lipid metabolism is a housekeeping function in energy homeostasis and biomembrane synthesis during pathogen replication and persistence. Lipids of enormous chemical diversity play roles as immunomodulatory factors. Thus, novel biochemical analytics in combination with cell and molecular biology are a promising recipe for dissecting the roles of lipids in host–pathogen interactions.
Glucuronoyl esterase – Novel carbohydrate esterase produced by Schizophyllum commune
Authors: Špániková Silvia , Biely Peter
Published: July 2006

The cellulolytic system of the wood‐rotting fungus Schizophyllum commune contains an esterase that hydrolyzes methyl ester of 4‐O‐methyl‐d‐glucuronic acid. The enzyme, called glucuronoyl esterase, was purified to electrophoretic homogeneity from a cellulose‐spent culture fluid. Its substrate specificity was examined on a number of substrates of other carbohydrate esterases such as acetylxylan esterase, feruloyl esterase and pectin methylesterase. The glucuronoyl esterase attacks exclusively the esters of MeGlcA. The methyl ester of free or glycosidically linked MeGlcA was not hydrolysed by other carbohydrate esterases. The results suggest that we have discovered a new type of carbohydrate esterase that might be involved in disruption of ester linkages connecting hemicellulose and lignin in plant cell walls.
Cyclic AMP delays neutrophil apoptosis via stabilization of Mcl‐1
Authors: Kato Takayuki , Kutsuna Haruo , Oshitani Nobuhide , Kitagawa Seiichi
Published: July 2006

Human neutrophils underwent spontaneous apoptosis, which was accompanied by degradation of Mcl‐1, but not other anti‐apoptotic molecules (cIAP1, cIAP2, A1, survivin and Bcl‐2). Spontaneous neutrophil apoptosis and Mcl‐1 degradation were prevented by cyclic AMP (cAMP) agonists (dibutyryl cAMP and prostaglandin E
1), and the effects of cAMP agonists on neutrophils were highly resistant to cycloheximide, a protein synthesis inhibitor, although slight increase in Mcl‐1 mRNA expression was induced by cAMP agonists. Proteasome inhibitors (epoxomicin and lactacystin) also prevented spontaneous neutrophil apoptosis and Mcl‐1 degradation to the same extent as cAMP agonists, and no additive effect was obtained by combination of cAMP agonists and proteasome inhibitors. These findings suggest that cAMP agonists, like proteasome inhibitors, delay neutrophil apoptosis primarily via stabilization of Mcl‐1.
Mutations which decouple the proton pump of the cytochrome c oxidase from Rhodobacter sphaeroides perturb the environment of glutamate 286
Authors: Vakkasoglu Ahmet S. , Morgan Joel E. , Han Dan , Pawate Ashtamurthy S. , Gennis Robert B.
Published: July 2006

Mutants that decouple the proton pump of cytochrome c oxidase from Rhodobacter sphaeroides are postulated to do so by increasing the pK
a of glutamate 286, which is 20 Å away. The possibility that a conformational change near E286 is induced by the decoupling mutations (N139D and N207D) was investigated by FTIR difference spectroscopy. In both decoupled mutants, the reduced‐minus‐oxidized FTIR difference spectra show a shift of 2 cm−1 to lower frequency of the band resulting from the absorbance of E286 in the oxidized enzyme. The decoupling mutants may influence E286 by altering the chain of water molecules which runs from the site of the mutations to E286.
The control of UCP1 is dissociated from that of PGC‐1α or of mitochondriogenesis as revealed by a study using β‐less mouse brown adipocytes in culture
Authors: Lehr Lorenz , Canola Kriss , Asensio Cedric , Jimenez Maria , Kuehne Françoise , Giacobino Jean-Paul , Muzzin Patrick
Published: July 2006

In rodent brown adipose tissue, the β‐adrenergic signaling is believed, by an action on PGC‐1α, to control UCP1 expression and mitochondriogenesis. We addressed this hypothesis using β1/β2/β3‐adrenoceptor knockout (β‐less) brown adipocytes in primary culture. In these cells: (a) proliferation and differentiation into multilocular cells were normal; (b) UCP1 mRNA expression was dramatically decreased (by 93%), whereas PGC‐1α and mtTFA mRNA expressions were not; (c) UCP1, PGC‐1α and COX IV protein expressions were decreased by 97%, 62% and 22%, respectively. Altogether the data show a dissociation between the control of UCP1, which is mostly β‐adrenoceptor‐dependent and that of PGC‐1α and of mitochondriogenesis which are not.
Curcumin abolishes apoptosis resistance of calcitriol‐differentiated HL‐60 cells
Authors: Mosieniak Grazyna , Sliwinska Malgorzata , Piwocka Katarzyna , Sikora Ewa
Published: July 2006

Exposure of HL‐60 cells to 1,25‐dihydroxyvitamin D3 (calcitriol) induces their differentiation into monocytes. This terminal differentiation is associated with acquired resistance to many proapoptotic stimuli. Here we show that differentiated HL‐60 cells undergo apoptosis upon curcumin treatment although they retain resistance to apoptosis induced by a topoisomerase poison – etoposide. Curcumin induced changes of nuclear morphology, DNA fragmentation, release of cytochrome c as well as caspase activation in both differentiated and undifferentiated cells. Experiments performed in other laboratories suggested that curcumin initiates apoptosis by DNA damage that results from topoisomerase II poisoning. We measured γH2AX expression, a marker of DNA double strand breaks, in both undifferentiated and differentiated HL‐60 cells treated with curcumin or etoposide. In etoposide‐treated undifferentiated cells early γH2AX expression correlated with initiation phase of apoptosis. In contrast, in curcumin‐treated cells γH2AX expression correlated with apoptotic DNA fragmentation, which is characteristic for the execution phase of apoptosis. Our experiments show that curcumin overcomes the resistance of calcitriol‐differentiated HL‐60 cells to DNA‐damage‐induced apoptosis by activating other cell signaling pathways leading to cell death of HL‐60.
The relevance of the phosphatidylinositolphosphat‐binding motif FRRGT of Atg18 and Atg21 for the Cvt pathway and autophagy
Authors: Krick Roswitha , Tolstrup Jörn , Appelles Anika , Henke Sandra , Thumm Michael
Published: July 2006

Atg18 and Atg21 are homologous S. cerevisiae autophagy proteins. Atg18 is essential for biogenesis of Cvt vesicles and autophagosomes, while Atg21 is only essential for Cvt vesicle formation. We found that mutated Atg18‐(FTTGT), which lost almost completely its binding to PtdIns3P and PtdIns(3,5)P2, is non‐functional during the Cvt pathway but active during autophagy and pexophagy. Since the Cvt pathway does not depend on PtdIns(3,5)P2, we conclude that the Cvt pathway requires binding of Atg18 to PtdIns3P. Mutated Atg21‐(FTTGT) is inactive during the Cvt pathway but showed only partly reduced binding to PtdIns‐phosphates, suggesting further lipid binding domains in Atg21. GFP‐Atg18‐(FTTGT) and Atg21‐(FTTGT)‐GFP are released from vacuolar punctae to the cytosol.
Inducible‐NOS but not neuronal‐NOS participate in the acute effect of TNF‐α on hypothalamic insulin‐dependent inhibition of food intake
Authors: Moraes Juliana C. , Amaral Maria E. , Picardi Paty K. , Calegari Vivian C. , Romanatto Talita , Bermúdez-Echeverry Marcela , Chiavegatto Silvana , Saad Mario J. , Velloso Licio A.
Published: July 2006

TNF‐α acts on the hypothalamus modulating food intake and energy expenditure through mechanisms incompletely elucidated. Here, we explore the hypothesis that, to modulate insulin‐induced anorexigenic signaling in hypothalamus, TNF‐α requires the synthesis of NO. TNF‐α activates signal transduction through JNK and p38 in hypothalamus, peaking at 10−8
M. This is accompanied by the induction of expression of the inducible and neuronal forms of NOS, in both cases peaking at 10−12
M. In addition, TNF‐α stimulates NOS catalytic activity. Pre‐treatment with TNF‐α at a low dose (10−12
M) inhibits insulin‐dependent anorexigenic signaling, and this effect is abolished in iNOS but not in nNOS knockout mice.
Microscopic rate‐constants for substrate binding and acylation in cold‐adaptation of trypsin I from Atlantic cod
Authors: Ásgeirsson Bjarni , Cekan Pavol
Published: July 2006

Temperature imposes limits on where life can thrive and this is evident in the evolution of the basic structural properties of proteins. Cold‐adaptation of enzymes is one example, where the catalytic rate constant (k
cat) is increased compared with hot‐acclimated homologous under identical assay conditions. Trypsin I from Atlantic cod (Gadus morhua) has catalytic efficiency (k
cat/K
m) for amide hydrolysis that is 17‐fold larger than observed for bovine trypsin. Here, the individual rate‐constants for association of substrate (k
1), dissociation of substrate (k
−1), and acylation of the enzyme (k
2) have been determined using benzoyl‐Arg‐p‐nitroanilide or benzyloxycarbonyl‐Gly‐Pro‐Arg‐p‐nitroanilide as substrates. Rather unexpectedly, by far the largest difference (37‐fold increase) was observed in k
1, the rate constant for binding of substrate. The cold‐adaptation of the dissociation and catalytic steps were not as prominent (increased by 3.7‐fold). The length of substrate did have an effect by increasing the reaction rate by 70‐fold, and again, the step most affected was the initial binding‐step.
CRY‐DASH gene expression is under the control of the circadian clock machinery in tomato
Authors: Facella Paolo , Lopez Loredana , Chiappetta Adriana , Bitonti Maria Beatrice , Giuliano Giovanni , Perrotta Gaetano
Published: July 2006

Recently a new member of the blue‐light photoreceptor family, CRY‐DASH, was reported in Arabidopsis, though its distinctive biological functions are still unclear. We characterized the CRY‐DASH gene of tomato and evidenced that its mRNA is expressed in both seeds and adult organs showing diurnal and circadian fluctuations. Moreover, the CRY‐DASH transcription pattern is altered in both in a cry1a mutant and in a transgenic CRY2 overexpressor suggesting that CRY‐DASH regulation must be mediated at least partially by an interaction of CRY1a and CRY2 with the timekeeping mechanism.
Cell type‐specific processing of human Tau proteins in Drosophila
Authors: Grammenoudi Sofia , Kosmidis Stylianos , Skoulakis Efthimios M.C.
Published: July 2006

Accumulation of hyperphosphorylated Tau is associated with a number of neurodegenerative diseases collectively known as tauopathies. Differences in clinical and cognitive profiles among them suggest differential sensitivity of neuronal populations to Tau levels, phosphorylation and mutations. We used tissue specific expression of wild type and mutant human tau transgenes to demonstrate differential phosphorylation and stability in a cell type‐specific manner, which includes different neuronal types and does not correlate with the level of accumulated protein. Rather, they likely reflect the spatial distribution or regulation of Tau‐targeting kinases and phosphatases.
A late Quaternary chironomid-inferred temperature record from the Sierra Nevada, California, with connections to northeast Pacific sea surface temperatures
Authors: Potito Aaron P. , Porinchu David F. , MacDonald Glen M. , Moser Katrina A.
Published: July 2006

Chironomid remains from a mid-elevation lake in the Sierra Nevada, California, were used to estimate quantitative summer surface water temperatures during the past ∼15,000 yr. Reconstructed temperatures increased by ∼3°C between lake initiation and the onset of the Holocene at ∼10,600 cal yr BP (calibrated years before present). Temperatures peaked at 6500 cal yr BP, displayed high variability from 6500 to 3500 cal yr BP, and stabilized after 3500 cal yr BP. This record generally tracks reconstructed Santa Barbara Basin sea surface temperatures (SSTs) through much of the Holocene, highlighting the correspondence between SST variability and California land temperatures during this interval.
Investigation of enhanced cross‐city transport and trapping of air pollutants by coastal and urban land‐sea breeze circulations
Authors: Lo Jeff C. F. , Lau Alexis K. H. , Fung Jimmy C. H. , Chen Fei
Published: July 2006

Recent satellite observations show that a layer of haze perpetually hangs over the Pearl River Delta (PRD) region and surface observations show numerous violations of the Hong Kong Air Quality Objective. This layer of haze mostly concentrates in the Pearl River Estuary and a narrow (20 km wide) band along the shoreline, in particular during weak wind situations. Although researchers suspect the land‐sea breeze (LSB) circulations “concentrate” or “trap” various pollutants in this region, the physical mechanism of the phenomenon has never been fully explained or quantified. In this paper, a mesoscale atmospheric model (MM5) coupled with the Noah land surface model (LSM), which has bulk urban land use treatments along with a detailed Pearl River Delta land use map, is used to investigate the unique feature and mechanism of this land‐sea breeze effect and the temporal evolution. A three‐dimensional particle trajectory model is used to understand its associated pollutant transport, trapping and accumulation. A conceptual model is then developed for the perpetual air pollution phenomenon in the region. Further sensitivity experiments are used to illustrate the impact of urbanization and large‐scale winds on the pollution processes. Results show that urbanization enhances the pollutant trapping and therefore contributes to the overall poor air quality in the region.
Transpacific transport of Asian anthropogenic aerosols and its impact on surface air quality in the United States
Authors: Heald Colette L. , Jacob Daniel J. , Park Rokjin J. , Alexander Becky , Fairlie T. Duncan , Yantosca Robert M. , Chu D. Allen
Published: July 2006

We use satellite (MODIS) observations of aerosol optical depths (AODs) over the North Pacific, together with surface aerosol measurements at a network of remote U.S. sites (IMPROVE), to improve understanding of the transpacific transport of Asian aerosol pollution and assess the ability of a global 3‐D chemical transport model (GEOS‐Chem CTM) to quantify Asian aerosol enhancements in U.S. surface air. The MODIS observations show the strongest transpacific transport occurring in spring at 40–55°N. This transport in the model takes place mainly in the lower free troposphere (900–700 hPa) because of scavenging during transport either in the boundary layer or during lifting to the upper troposphere. The preferential altitude of aerosol transpacific transport results in direct impact on the elevated terrain of the NW United States. Sulfate observations in the NW United States in spring 2001 show higher concentrations on the days of model‐predicted maximum Asian influence (1.04 μg m−3) than seasonal mean values (0.69 μg m−3). No such Asian enhancements are observed for nitrate or for organic carbon (OC) aerosol. Distinct Asian sulfate episodes correlated with dust events are observed in the NW United States and simulated with the model. The mean Asian pollution enhancement in that region in spring is 0.16 μg m−3 with a 50% estimated uncertainty. This is higher than the estimated natural concentration of 0.09 μg m−3 presently used as objective for regulation of visibility in U.S. wilderness areas.
Thermodynamic, cloud microphysics, and rainfall responses to initial moisture perturbations in the tropical deep convective regime
Authors: Li Xiaofan , Zhang Shunli , Zhang Da‐Lin
Published: July 2006

In this study, the precipitable water (PW) and ice water path (IWP) simulated by the Global Data Assimilation System (GDAS) are compared to those observed by NOAA's Microwave Surface and Precipitation Products System. Results show small root‐mean‐square (RMS) differences in PW but large RMS differences in IWP between the two data sets, indicating the existence of model errors in reproducing clouds. To examine the possible linkage between the small PW and large IWP differences, three experiments are conducted with a two‐dimensional cloud‐resolving model in which the observed zonal wind and the GDAS‐derived large‐scale vertical velocity are imposed. The model initial conditions of PW are perturbed by ±10% in the first two experiments, respectively, while treating the third one without any perturbation as a control simulation. Thermodynamic, cloud microphysics, and precipitation budgets are then calculated from the zonally averaged and vertically integrated data at hourly intervals from these experiments. Results show the generation of larger differences in the cloud hydrometeors and surface rain rates, with the given PW perturbations. This indicates that the model‐simulated clouds and precipitation are extremely sensitive to the initial errors in PW, primarily through the biased condensation process.
Influence of summertime deep convection on formaldehyde in the middle and upper troposphere over Europe
Authors: Stickler A. , Fischer H. , Williams J. , de Reus M. , Sander R. , Lawrence M. G. , Crowley J. N. , Lelieveld J.
Published: July 2006

We present HCHO measurements performed during the Upper Tropospheric Ozone: Processes Involving HOx and NOx (UTOPIHAN) II aircraft campaign over central‐western Europe and the northwestern Mediterranean region in 2003 and 2004. We compare these with box model and three‐dimensional (3‐D) chemistry‐transport model results for “background” and “convective” conditions. Generally, we obtain good agreement between the model and measurement data, although the 3‐D model tends to underestimate HCHO near the tropopause, whereas the box model tends to slightly overestimate HCHO for the background case. Sensitivity simulations indicate that the most important factors determining HCHO concentrations are the abundances of NO, reactive hydrocarbons (e.g., isoprene), CH3OOH, CH3OH, and acetone and also the level of irradiance. In the middle and upper troposphere the most important HCHO production term is the reaction of CH3O2 with NO (68 ± 10%, including a contribution of 38 ± 7% from CH4 oxidation), followed by the destruction of CH3OOH by OH and photolysis (14 ± 2%), and the reaction of CH3OH with OH (14 ± 8%). HCHO loss is dominated by photolysis rather than by the reaction with OH, except in the upper tropospheric convective case, where the loss by OH contributes about 50%. Our measurements furthermore indicate that convective transport of H2O2 can be very efficient.
Validation of the Moderate‐Resolution Imaging Spectroradiometer precipitable water vapor product using measurements from GPS on the Tibetan Plateau
Authors: Liu Jingmiao , Liang Hong , Sun Zhian , Zhou Xiuji
Published: July 2006

Moderate‐Resolution Imaging Spectroradiometer (MODIS) Global atmospheric column water vapor amount product (MOD05_L2) released by NASA Goddard DAAC was evaluated using 1 year of observations obtained by the Global Positioning System (GPS) installed at Gaize (32.3°N, 84.06°E, 4420 m) and Naqu (30.48°N, 92.06°E, 4518 m) on the Tibetan Plateau. It was found that the MODIS retrieved atmospheric column water vapor amount is much lower than that retrieved by GPS at the two sites. The results show that there is a systematic bias in precipitable water between MODIS and GPS, with root‐mean‐square errors (rms) of 2.93 mm at Naqu and 3.48 mm at Gaize. Mean relative differences in PW between GPS and MODIS at Naqu and Gaize are 57.1% and 51.1%, respectively. The reason for the bias is found to be an error in the coding of operational water vapor retrievals at the NASA Goddard DAAC for data processing. After correction for the MODIS water vapor product (MOD05_L2), the RMS difference between GPS‐PW and MODIS‐PW drops to 1.9 mm at Naqu and 1.68 mm at Gaize.
Bridging river basin scales and processes to assess human‐climate impacts and the terrestrial hydrologic system
Authors: Reed Patrick M. , Brooks Robert P. , Davis Kenneth J. , DeWalle David R. , Dressler Kevin A. , Duffy Chistopher J. , Lin Hangsheng , Miller Douglas A. , Najjar Raymond G. , Salvage Karen M. , Wagener Thorsten , Yarnal Brent
Published: July 2006

The increasing expression of human activity, climate variability, and climate change on humid, terrestrial hydrologic systems has made the integrated nature of large river basins more apparent. However, to date, there is no instrument platform sufficient to characterize river basins' hydrologic couplings and feedbacks, with many processes and impacts left almost entirely unobserved (e.g., snowmelt floods). Characterization at the river basin scale will require a more holistic vision and a far greater commitment from the environmental science community. It will require new designs and implementation of integrated instrumentation, a new generation of models, and a management framework that clearly addresses the human‐climate‐terrestrial interactions impacting our watersheds and river basins. Initially, we propose that existing “similarity classifications” (e.g., regional soil, geologic, ecologic, hydrographic digital products) can provide a starting point for organizing historical data and initiating a long‐term adaptive, multiscale observing strategy. This vision paper outlines instrumentation platforms for point, plot, reach, and hillslope scales that could be located within the “characteristic” landscapes of river basins. The network of observing platforms then forms the basis of a “Hydro‐Mesonet” that can potentially support multiscale, multiprocess scientific studies necessary to understand and improve forecasts of our water resources at the river basin scale. This paper concludes with a discussion of how a network of such sites can support research at the level of the individual researcher and scale to the level of community‐wide initiatives.
Multiobjective particle swarm optimization for parameter estimation in hydrology
Authors: Gill M. Kashif , Kaheil Yasir H. , Khalil Abedalrazq , McKee Mac , Bastidas Luis
Published: July 2006

Modeling of complex hydrologic processes has resulted in models that themselves exhibit a high degree of complexity and that require the determination of various parameters through calibration. In the current application we introduce a relatively new global optimization tool, called particle swarm optimization (PSO), that has already been applied in various other fields and has been reported to show effective and efficient performance. The PSO approach initially dealt with a single‐objective function but has been extended to deal with multiobjectives in a form called multiobjective particle swarm optimization (MOPSO). The algorithm is modified to account for multiobjective problems by introducing the Pareto rank concept. The new MOPSO algorithm is tested on three case studies. Two test functions are used as the first case study to generate the true Pareto fronts. The approach is further tested for parameter estimation of a well‐known conceptual rainfall‐runoff model, the Sacramento soil moisture accounting model having 13 parameters, for which the results are very encouraging. We also tested the MOPSO algorithm to calibrate a three‐parameter support vector machine model for soil moisture prediction.
Effects of sampling frequency on estimates of dissolved silica export by streams: The role of hydrological variability and concentration‐discharge relationships
Authors: Stelzer Robert S. , Likens Gene E.
Published: July 2006

Accurate estimates of solute export are critical for mass balance studies of elemental flux. We explored how variation in hydrology (e.g., flashiness) and concentration‐discharge relationships modulate the effect of solute sampling frequency on bias and precision associated with estimates of dissolved silica export in rivers. Dissolved silica concentration and discharge data from 14 rivers were used to parameterize a nonlinear concentration‐discharge model, which was used to generate simulated data for daily dissolved silica concentration for 20 rivers. We determined how solute sampling at various intervals affects bias, precision, and root‐mean‐square error of export estimates. Bias and coefficient of variation of dissolved silica export increased with coarser sampling intervals. Flashiness and the coefficient of variation of daily discharge typically explained 90% or more of the variation in bias and precision of dissolved silica export, particularly at finer sampling intervals. Our analysis should be useful to researchers and land managers who are planning or evaluating sampling programs to determine solute flux or who seek error estimates for solute export.
Influence of mechanical mixing on a low summertime SST in the western North Pacific ITCZ region
Authors: Sato N. , Tokinaga H. , Shirooka R. , Suginohara N.
Published: July 2006

A region with a low sea‐surface temperature (SST) was identified in the western North Pacific (WNP) Intertropical Convergence Zone (ITCZ) or warm water pool region in boreal summer. The SST decreases by up to 0.5°C from May to the June–July–August (JJA) season just east of Mindanao Island. Analyses of the observed data indicated that a northeastward surface current constantly exists throughout the year, supplying cold subsurface water through the Molucca Strait. As a result, the subsurface water is colder by several degrees compared with that in the surrounding regions. The sea‐surface wind is strong over this region in the JJA season. Examination of Argo float data demonstrated that the mixed layer becomes deeper from May to the JJA season. It is suggested that the strong wind causes vertical mixing between the surface and subsurface layers, resulting in the low summertime SST.
Observations of strong gyro line spectra at Arecibo near dawn
Authors: Bhatt A. N. , Gerken Kendall E. A. , Kelley M. C. , Sulzer M. P. , Shume E. B.
Published: July 2006

Experiments performed near dawn during the PARS Summer School at Arecibo in August 2004 show clear evidence of the gyro line in the incoherent scatter radar (ISR) spectra with only six minutes of signal integration. A very weak gyro line was first observed by Behnke and Hagen (1978) requiring two hours of signal integration. Electrons that resonate with the gyro wave mode are well within the thermal distribution. At this point we know of no theory to explain the magnitude of the gyro lines we have detected although it seems clear that the presence of photoelectrons is related to it. We present the experimental results and a comparison with an incoherent scatter numerical model based on the theory developed by Trulsen and Bjørn (1978), which shows a very good correlation. From this comparison, and by combining the gyro line and the plasma line techniques, it is possible to make electron temperature measurements.
Sequential stagnation of Kamb Ice Stream, West Antarctica
Authors: Catania G. A. , Scambos T. A. , Conway H. , Raymond C. F.
Published: July 2006

Ice‐penetrating radar data confirm the presence of two relict northern margins of Kamb Ice Stream (KIS), West Antarctica in an area called the Duckfoot. Between the two relict margins, deep layers are preserved and buried crevasses remain at a constant depth until roughly 1.5 km from the innermost (youngest) margin suggesting that this outer portion of the ice stream stagnated suddenly (<10 years). Stagnation was likely accomplished through changes in basal conditions (i.e., reduced lubrication) beneath this outer portion of the ice stream and resulted in a narrowing of the ice stream trunk by 27% and a reduction in flow speed ∼200 years prior to complete stagnation. Flowstripe deformation as a result of Duckfoot stagnation provides an estimate of KIS paleo‐velocity of 210 m/a after Duckfoot stagnation.
On the forecast of cumulative precipitation at subseasonal time‐scales over the Sahel
Authors: Vintzileos Augustin , Thiaw Wassila M.
Published: July 2006

The Sahel, which is considered to be amongst the climate sensitive regions for its history of droughts and famine, and excessive precipitation and disease, is also a source for easterly waves, which upon encountering favorable conditions over the Atlantic Ocean, transform into hurricanes. Benefits from the successful forecast of key variables at subseasonal time scales are obvious. We demonstrate the capacity of the current operational version of the Climate Forecasting System (CFS) of the National Centers for Environmental Prediction (NCEP) to provide skillful forecasts of cumulative precipitation at subseasonal time‐scales over the Sahel region. For this we use the database of subseasonal‐to‐seasonal retrospective forecasts conducted at NCEP for the period from 1982 to 2004. Both measures of deterministic and probabilistic scores are used.
Decreasing magmatic footprints of individual volcanoes in a waning basaltic field
Authors: Valentine G. A. , Perry F. V.
Published: July 2006

The distribution and characteristics of individual basaltic volcanoes in the waning Southwestern Nevada Volcanic Field provide insight into the changing physical nature of magmatism and the controls on volcano location. During Pliocene‐Pleistocene times the volumes of individual volcanoes have decreased by more than one order of magnitude, as have fissure lengths and inferred lava effusion rates. Eruptions evolved from Hawaiian‐style eruptions with extensive lavas to eruptions characterized by small pulses of lava and Strombolian to violent Strombolian mechanisms. These trends indicate progressively decreasing partial melting and length scales, or magmatic footprints, of mantle source zones for individual volcanoes. The location of each volcano is determined by the location of its magmatic footprint at depth, and only by shallow structural and topographic features that are within that footprint. The locations of future volcanoes in a waning system are less likely to be determined by large‐scale topography or structures than were older, larger volume volcanoes.
Acceptor segregation and nonlinear current-voltage characteristics in H2-sintered SrTiO3
Authors: Wang Seong-Min , Kang Suk-Joong L.
Published: July 2006

The current-voltage characteristics with acceptor segregation at grain boundaries have been investigated in H2-sintered SrTiO3. Al-added SrTiO3 was sintered in H2 and then annealed in air for selective oxidation of grain boundaries. The samples showed nonlinear current-voltage characteristics, and both the breakdown voltage and nonlinearity coefficient increased with Al concentration. An energy dispersive spectroscopy analysis revealed that Al ions were segregated at the grain boundary, suggesting the formation of Schottky barriers at the boundary. The present results thus point toward the possibility of modifying the grain boundary composition in SrTiO3 as well as fabricating effective switching devices by H2 sintering.
Molecular transport through channels and pores: Effects of in-channel interactions and blocking
Authors: Bauer Wolfgang R. , Nadler Walter
Published: July 2006

Facilitated translocation of molecules through channels and pores is of fundamental importance for transmembrane transport in biological systems. Several such systems have specific binding sites inside the channel, but a clear understanding of how the interaction between channel and molecules affects the flow is still missing. We present a generic analytical treatment of the problem that relates molecular flow to the first passage time across and the number of particles inside the channel. Both quantities depend in different ways on the channel properties. For the idealized case of noninteracting molecules, we find an increased flow whenever there is a binding site in the channel, despite an increased first passage time. In the more realistic case that molecules may block the channel, we find an increase of flow only up to a certain threshold value of the binding strength and a dependence on the sign of the concentration gradient, i.e., asymmetric transport. The optimal binding strength in that case is analyzed. In all cases the reason for transport facilitation is an increased occupation probability of a particle inside the channel that overcomes any increase in the first passage time because of binding.
A nutrient uptake role for bacterial cell envelope extensions
Authors: Wagner Jennifer K. , Setayeshgar Sima , Sharon Laura A. , Reilly James P. , Brun Yves V.
Published: July 2006

Bacteria exist in a variety of morphologies, but the relationship between cellular forms and biological functions remains poorly understood. We show that stalks (prosthecae), cylindrical extensions of the
Caulobacter crescentus
cell envelope, can take up and hydrolyze organic phosphate molecules and contain the high-affinity phosphate-binding protein PstS, but not PstA, a protein that is required for transport of phosphate into the cytoplasm. Therefore, uptake, hydrolysis, and periplasmic binding of a phosphate source can take place in the stalk, but high-affinity import must take place in the cell body. Furthermore, by using analytical modeling, we illustrate the biophysical advantage of the stalk as a morphological adaptation to the diffusion-limited, oligotrophic environments where
C. crescentus
thrives. This advantage is due to the fact that a stalk is long and thin, a favorable shape for maximizing contact with diffusing nutrients while minimizing increases in both surface area and cell volume.
A mechanism to signal receptor–substrate interactions with luminescent quantum dots
Authors: Yildiz Ibrahim , Tomasulo Massimiliano , Raymo Françisco M.
Published: July 2006

Semiconductor quantum dots are becoming valuable analytical tools for biomedical applications. Indeed, their unique photophysical properties offer the opportunity to design luminescent probes for imaging and sensing with unprecedented performance. In this context, we have identified operating principles to transduce the supramolecular association of complementary receptor–substrate pairs into an enhancement in the luminescence of sensitive quantum dots. Our mechanism is based on the electrostatic adsorption of cationic quenchers on the surface of anionic quantum dots. The adsorbed quenchers suppress efficiently the emission character of the associated nanoparticles on the basis of photoinduced electron transfer. In the presence of target receptors able to bind the quenchers and prevent electron transfer, however, the luminescence of the quantum dots is restored. Thus, complementary receptor–substrate pairs can be identified with luminescence measurements relying on our design logic. In fact, we have demonstrated with a representative example that our protocol can be adapted to signal protein–ligand interactions.
Last Interglacial marine environments in the White Sea region, northwestern Russia
Authors: GRØSFJELD KARI , FUNDER SVEND , SEIDENKRANTZ MARIT‐SOLVEIG , GLAISTER CHRIS
Published: July 2006

Marine sediments from river sections in the Mezen River drainage, northwest Russia, have been analysed for dinoflagellate cysts, foraminifers and molluscs. The sediments were dated by pollen analysis and by reference to the local sea‐level history, and are Late Saalian to late Eemian (c. 133 to 119.5 kyr in age). The Late Saalian deglaciation was characterized by Arctic conditions, but a few centuries into the Eemian the Gulf Stream system carried warm Atlantic water into the region. At 129.8 kyr BP there was a marked increase in the influx of Atlantic water, and the advection of warm Atlantic water was stronger and probably penetrated further eastwards than at present. The molluscs, dinoflagellate cysts and foraminifers reflect conditions warmer than present and that the optimum temperature occurred at the time of the early Eemian global sea‐level rise. Around 128 kyr BP, the eustatic sea‐level rise was curbed by isostatic rebound and accompanying regression and constriction of marine passages to the White Sea. Local, low‐saline, stratified basins developed and characterized the next five to six millennia.
Early Weichselian palaeoenvironments reconstructed from a mega‐scale thrust‐fault complex, Kanin Peninsula, northwestern Russia
Authors: LARSEN EILIV , KJæR KURT H. , JENSEN MARIA , DEMIDOV IGOR N. , HAKANSSON LENA , PAUS AAGE
Published: July 2006

A section, almost 20 km long and up to 80 m high, through alternating layers of diamict and sorted sediments is superbly exposed on the north coast of the Kanin Peninsula, northwestern Russia. The diamicts represent multiple glacial advances by the Barents Sea and the Kara Sea ice sheets during the Weichselian. The diamicts and stratigraphically older lacustrine, fluvial and shallow marine sediments have been thrust as nappes by the Barents Sea and Kara Sea ice sheets. Based on stratigraphic position, OSL dating, sea level information and pollen, it is evident that the sorted sediments were deposited in the Late Eemian‐Early Weichselian. Sedimentation started in lake basins and continued in shallow marine embayments when the lakes opened to the sea. The observed transition from lacustrine to shallow marine sedimentation could represent coastal retreat during stable or rising sea level.
Depositional environments and sea‐level changes deduced from Middle Weichselian tidally influenced sediments, Arkhangelsk region, northwestern Russia
Authors: JENSEN MARIA , LARSEN EILIV , DEMIDOV IGOR N. , FUNDER SVEND , KJæR KURT H.
Published: July 2006

Deposits from a Middle Weichselian transgression, the Mezen Transgression, are found in coastal sections in the Mezen and Chyorskaya Bays, northwestern Russia. The marine event is bracketed between two ice advances from the Barents and Kara Sea shelves and dated by Optically Stimulated Luminescence (OSL) to around 60 kyr BP. The deposits represent a shallowing upward succession from offshore marine to intertidal coastal environments. Relative sea‐level maximum was at least 40 m above the present owing to significant isostatic subsidence. The sedimentary record is dominated by shallow‐marine, subtidal deposits bounded below by an erosion surface representing a downward shift in facies and above by subaerial exposure. The succession reflects deposition during forced regression due to isostatic uplift. A rapidly aggrading succession of subtidal deposits at one site suggests a relative sea‐level rise or stillstand superimposed on the isostatically controlled sea‐level fall. The rhythmic tidal deposits allow identification of semi‐monthly to yearly cycles, providing an estimate of the sedimentation rate of 39 cm/year. This implies a high sediment yield and a rapid relative sea‐level rise. We correlate this signal with the rapid eustatic sea‐level rise at the end of OIS 4 known from deep‐sea records.
Late Pleistocene glacial and lake history of northwestern Russia
Authors: LARSEN EILIV , KJæR KURT H. , DEMIDOV IGOR N. , FUNDER SVEND , GRØSFJELD KARI , HOUMARK‐NIELSEN MICHAEL , JENSEN MARIA , LINGE HENRIETTE , LYSA ASTRID
Published: July 2006

Five regionally significant Weichselian glacial events, each separated by terrestrial and marine interstadial conditions, are described from northwestern Russia. The first glacial event took place in the Early Weichselian. An ice sheet centred in the Kara Sea area dammed up a large lake in the Pechora lowland. Water was discharged across a threshold on the Timan Ridge and via an ice‐free corridor between the Scandinavian Ice Sheet and the Kara Sea Ice Sheet to the west and north into the Barents Sea. The next glaciation occurred around 75–70 kyr BP after an interstadial episode that lasted c. 15 kyr. A local ice cap developed over the Timan Ridge at the transition to the Middle Weichselian. Shortly after deglaciation of the Timan ice cap, an ice sheet centred in the Barents Sea reached the area. The configuration of this ice sheet suggests that it was confluent with the Scandinavian Ice Sheet. Consequently, around 70–65 kyr BP a huge ice‐dammed lake formed in the White Sea basin (the ‘White Sea Lake’), only now the outlet across the Timan Ridge discharged water eastward into the Pechora area. The Barents Sea Ice Sheet likely suffered marine down‐draw that led to its rapid collapse. The White Sea Lake drained into the Barents Sea, and marine inundation and interstadial conditions followed between 65 and 55 kyr BP. The glaciation that followed was centred in the Kara Sea area around 55–45 kyr BP. Northward directed fluvial runoff in the Arkhangelsk region indicates that the Kara Sea Ice Sheet was independent of the Scandinavian Ice Sheet and that the Barents Sea remained ice free. This glaciation was succeeded by a c. 20‐kyr‐long ice‐free and periglacial period before the Scandinavian Ice Sheet invaded from the west, and joined with the Barents Sea Ice Sheet in the northernmost areas of northwestern Russia. The study area seems to be the only region that was invaded by all three ice sheets during the Weichselian. A general increase in ice‐sheet size and the westwards migrating ice‐sheet dominance with time was reversed in Middle Weichselian time to an easterly dominated ice‐sheet configuration. This sequence of events resulted in a complex lake history with spillways being re‐used and ice‐dammed lakes appearing at different places along the ice margins at different times.
Early ageing in middle-aged men is associated with adverse social factors and increased mortality risk: The Malmö Preventive Project
Authors: Tell David , Nilsson Peter M.
Published: July 2006

Aims: This study examined whether middle-aged men exhibiting markers of early ageing showed a different pattern of social factors, lifestyle, and biological variables compared with controls, and whether early ageing was associated with an increased mortality risk. Subjects and methods: We used a subgroup of 5,722 middle-aged men (mean age 47 years), investigated twice, from the Malmö Preventive Project (MPP), a screening programme attended by a total of 22,444 men between 1974 and 1992. Markers of biological ageing, such as decreased lung function, increased pulse pressure, and decreased height, were used to identify early aged subjects and a control group. These were followed up by use of local and national registers for a mean of 22 years. Cox's proportional regression was used to estimate multivariate relative risks (RR) for mortality with 95% confidence intervals (CI). Results: Men with early ageing were more often smokers, living alone, or less likely to be non-manual workers than control subjects. These men also had an increased age-adjusted mortality relative risk, RR 1.29 (95% CI 1.10—1.52). After adjustment for social and lifestyle factor there was still a significant difference in mortality between the two groups, RR 1.19 (95% CI 1.00—1.42). Conclusion: Early biological ageing in middle-aged men is associated with an increased mortality risk during long-term follow-up that cannot be fully explained by social background characteristics or adverse lifestyle.
Brick Wall Model and the Spectrum of a Schwarzschild Black Hole
Authors: Li Xiang  , Zhao Zheng
Published: July 2006

The quantum entropy of a scalar field near a Schwarzschild black hole is investigated by employing the brick-wall model in the grand canonical ensemble. A positive chemical potential is introduced if the cutoff is set to be of order of the Planck length. We also discuss the relation between the chemical potential and the mass quantum of the black hole.
Characterization of a Novel Plant Promoter Specifically Induced by Heavy Metal and Identification of the Promoter Regions Conferring Heavy Metal Responsiveness
Authors: Qi Xiaoting , Zhang Yuxiu , Chai Tuanyao
Published: July 2006

The bean (Phaseolus vulgaris) stress-related gene number 2 (PvSR2) gene responds to heavy metals but not to other forms of environmental stresses. To elucidate its heavy metal-regulatory mechanism at the transcriptional level, we isolated and characterized the promoter region (−1623/+48) of PvSR2. Deletions from the 5′ end revealed that a sequence between −222 and −147 relative to the transcriptional start site was sufficient for heavy metal-specific induction of the promoter region of PvSR2. Detailed analysis of this 76-bp fragment indicated that heavy metal-responsive elements were localized in two regions (−222/−188 and −187/−147), each of which could separately confer heavy metal-responsive expression on the β-glucuronidase gene in the context of a minimal cauliflower mosaic virus 35S promoter. Region I (−222/−188) contains a motif (metal-regulatory element-like sequence) similar to the consensus metal-regulatory element of the animal metallothionein gene, and mutation of this motif eliminated the heavy metal-inducible function of region I. Region II (−187/−147) had no similarity to previously identified cis-acting elements involved in heavy metal induction, suggesting the presence of a novel heavy metal-responsive element. Transformed tobacco (Nicotiana tabacum) seedlings expressing β-glucuronidase under control of the PvSR2 promoter region (−687/+48) showed heavy metal-specific responsive activity that depended on the type and concentration of the heavy metal and the type of organ. These findings further our understanding of the regulation of PvSR2 expression and provide a new heavy-metal-inducible promoter system in transgenic plants.