bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contribution of Urease to Colonization by Shiga Toxin-Producing Escherichia coli
Authors: Steyert Susan R. , Kaper James B. 
Published: June 2012

ABSTRACT

Shiga toxin-producing
Escherichia coli
(STEC) is a food-borne pathogen with a low infectious dose that colonizes the colon in humans and can cause severe clinical manifestations such as hemolytic-uremic syndrome. The urease enzyme, encoded in the STEC chromosome, has been demonstrated to act as a virulence factor in other bacterial pathogens. The NH
3
produced as urease hydrolyzes urea can aid in buffering bacteria in acidic environments as well as provide an easily assimilated source of nitrogen that bacteria can use to gain a metabolic advantage over intact microflora. Here, we explore the role of urease in STEC pathogenicity. The STEC urease enzyme exhibited maximum activity near neutral pH and during the stationary-growth phase. Experiments altering growth conditions performed with three phylogenetically distinct urease-positive strains demonstrated that the STEC
ure
gene cluster is inducible by neither urea nor pH but does respond to nitrogen availability. Quantitative reverse transcription-PCR (qRT-PCR) data indicate that nitrogen inhibits the transcriptional response. The deletion of the
ure
gene locus was constructed in STEC strain 88-0643, and the
ure
mutant was used with the wild-type strain in competition experiments in mouse models to examine the contribution of urease. The wild-type strain was twice as likely to survive passage through the acidic stomach and demonstrated an enhanced ability to colonize the intestinal tract compared to the
ure
mutant strain. These
in vivo
experiments reveal that, although the benefit STEC gains from urease expression is modest and not absolutely required for colonization, urease can contribute to the pathogenicity of STEC.
Age and structure of the Crevice pluton: overlapping orogens in west-central Idaho?
Authors: Gray Keith D. , Watkinson A. John , Gaschnig Richard M. , Isakson Vincent H. 
Published: June 2012

New U–Pb zircon geochronology from the Riggins region of west-central Idaho refines the timing of contractional deformation across the Salmon River suture zone (SRSZ), a broad north- to northeast-striking belt (>25 km wide) of high strain recording Jura-Cretaceous island-arc–continent collision. Laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) yields mid-Cretaceous crystallization ages on formerly undated plutonic rocks sampled from the Salmon River canyon. In the Crevice pluton (∼105 Ma), the development of steep to moderate northerly striking gneissic foliation (S1) was followed by tops-to-the-west slip on shallow mylonitic shear zones (S2) and brittle overprinting via systematic joints (Jn) of regional extent. Together, these structures form the pluton’s internal architecture. Subvertical gneissic foliation in the adjacent Looking Glass pluton (∼92 Ma) indicates ductile deformation was ongoing in the Late Cretaceous. Prior to this investigation, penetrative fabrics in local arc volcanogenic, plutonic, and continental rocks have been unequivocally linked to post-collisional dextral transpression on the narrow (<10 km wide) western Idaho shear zone (WISZ). As an alternative to this model which requires spatially overlapping but temporally distinct orogenic belts (WISZ–SRSZ), we consider a protracted history whereby regional synmetamorphic structures accumulated over a pre-118 Ma to post-92 Ma interval without an overprinting orogen-scale ductile shear zone. In our view, a progressive deformation history more accurately accounts for the time-transgressive nature and structural continuity of fabrics observed across the arc–continent transition. This tectonic history proposed for western Idaho may be analogous to other long-lived accretionary margins in the North American Cordillera (e.g., Omineca Belt of southeastern British Columbia).
U–Pb zircon age of an Ordovician tuff in southeast Yukon: implications for the age of the Cambrian–Ordovician boundary1Yukon Geological Survey Contribution 013.2Geological Survey of Canada Earth Science Sector (ESS) Contribution 20110362.
Authors: Pigage L.C. , Crowley J.L. , Pyle L.J. , Abbott J.G. , Roots C.F. , Schmitz M.D. 
Published: June 2012

Three conodont fossil occurrences stratigraphically above and below a rhyolitic tuff in the Lower Ordovician Crow Formation, southeast Yukon, constrain the tuff to the early Tremadocian Rossodus manitouensis Zone and possibly the Rossodus tenuis Zone. U–Pb dates were obtained from zircon from the tuff that was imaged with cathodoluminescence and chemically abraded to reduce the likelihood of dating grains that contain older components or suffered Pb loss, respectively. Six dates from grains with oscillatory parallel zoning are equivalent, with a weighted mean 206Pb/238U date of 491.04 ± 0.13 Ma. These grains are interpreted as being primary volcanic crystals, and the date is therefore taken as the depositional age of the tuff. Four other dates from grains with sector zoning are slightly older, up to 492.0 Ma, and are interpreted as inherited or recycled from earlier volcanics. The currently defined Cambrian–Ordovician boundary is inferred to be below the tuff and separated from it by at least two conodont biostratigraphic zones that are estimated to span at least 2.25 Ma based on the top of the Rhabdinopora flabelliformis parabola graptolite zone being older than the base of the Rossodus tenuis conodont zone. We interpret the evidence in southeast Yukon to suggest that the global Cambrian–Ordovician boundary is older (>493.3 Ma) than previous estimates of ∼488 and 491 Ma based upon legacy 207Pb/206Pb zircon ages.
Analysis of Workload Behavior in Scientific and Historical Long-Term Data Repositories
Authors: Adams Ian F. , Storer Mark W. , Miller Ethan L. 
Published: June 2012

The scope of archival systems is expanding beyond cheap tertiary storage: scientific and medical data is increasingly digital, and the public has a growing desire to digitally record their personal histories. Driven by the increase in cost efficiency of hard drives, and the rise of the Internet, content archives have become a means of providing the public with fast, cheap access to long-term data. Unfortunately, designers of purpose-built archival systems are either forced to rely on workload behavior obtained from a narrow, anachronistic view of archives as simply cheap tertiary storage, or extrapolate from marginally related enterprise workload data and traditional library access patterns.To close this knowledge gap and provide relevant input for the design of effective long-term data storage systems, we studied the workload behavior of several systems within this expanded archival storage space. Our study examined several scientific and historical archives, covering a mixture of purposes, media types, and access models---that is, public versus private. Our findings show that, for more traditional private scientific archival storage, files have become larger, but update rates have remained largely unchanged. However, in the public content archives we observed, we saw behavior that diverges from the traditional “write-once, read-maybe” behavior of tertiary storage. Our study shows that the majority of such data is modified---sometimes unnecessarily---relatively frequently, and that indexing services such as Google and internal data management processes may routinely access large portions of an archive, accounting for most of the accesses. Based on these observations, we identify areas for improving the efficiency and performance of archival storage systems.
Fibulin-3 Promotes Glioma Growth and Resistance through a Novel Paracrine Regulation of Notch Signaling
Authors: Hu Bin , Nandhu Mohan S. , Sim Hosung , Agudelo-Garcia Paula A. , Saldivar Joshua C. , Dolan Claire E. , Mora Maria E. , Nuovo Gerard J. , Cole Susan E. , Viapiano Mariano S. 
Published: June 2012

Abstract
Malignant gliomas are highly invasive and chemoresistant brain tumors with extremely poor prognosis. Targeting of the soluble factors that trigger invasion and resistance, therefore, could have a significant impact against the infiltrative glioma cells that are a major source of recurrence. Fibulin-3 is a matrix protein that is absent in normal brain but upregulated in gliomas and promotes tumor invasion by unknown mechanisms. Here, we show that fibulin-3 is a novel soluble activator of Notch signaling that antagonizes DLL3, an autocrine inhibitor or Notch, and promotes tumor cell survival and invasion in a Notch-dependent manner. Using a strategy for inducible knockdown, we found that controlled downregulation of fibulin-3 reduced Notch signaling and led to increased apoptosis, reduced self-renewal of glioblastoma-initiating cells, and impaired growth and dispersion of intracranial tumors. In addition, fibulin-3 expression correlated with expression levels of Notch-dependent genes and was a marker of Notch activation in patient-derived glioma samples. These findings underscore a major role for the tumor extracellular matrix in regulating glioma invasion and resistance to apoptosis via activation of the key Notch pathway. More importantly, this work describes a noncanonical, soluble activator of Notch in a cancer model and shows how Notch signaling can be reduced by targeting tumor-specific accessible molecules in the tumor microenvironment. Cancer Res; 72(15); 3873–85. ©2012 AACR.
Analysis of Spatiotemporal Balancing between Wind and Solar Energy Resources in the Southern Iberian Peninsula
Authors: Santos-Alamillos F. J. , Pozo-Vázquez D. , Ruiz-Arias J. A. , Lara-Fanego V. , Tovar-Pescador J. 
Published: June 2012

AbstractElectricity from wind and, to a lesser extent, solar energy is intermittent and not controllable. Unlike conventional power generation, therefore, this electricity is not suitable to supply base-load electric power. In the future, with greater penetration of these renewable sources, intermittency and control problems will become critical. Here, the authors explore the use of canonical correlation analysis (CCA) for analyzing spatiotemporal balancing between regional solar and wind energy resources. The CCA allows optimal distribution of wind farms and solar energy plants across a territory to minimize the variability of total energy input into the power supply system. The method was tested in the southern half of the Iberian Peninsula, a region covering about 350 000 km2. The authors used daily-integrated wind and solar energy estimates in 2007 from the Weather Research and Forecasting (WRF) mesoscale model, at a spatial resolution of 9 km. Results showed valuable balancing patterns in the study region, but with a marked seasonality in strength, sign, and spatial coverage. The autumn season showed the most noteworthy results, with a balancing pattern extending almost over the entire study region. With location of reference wind farms and photovoltaic (PV) plants according to the balancing patterns, their combined power production shows substantially lower variability than production of the wind farms and PV plants separately and combined production obtained with any other locations. Atmospheric circulations associated with the balancing patterns were found to be significantly different between seasons. In this regard, synoptic-scale variability played an important role, but so did topographic conditions, especially near the Strait of Gibraltar.
Atmospheric and Fuel Moisture Characteristics Associated with Lightning-Attributed Fires
Authors: Dowdy Andrew J. , Mills Graham A. 
Published: June 2012

AbstractA systematic examination is presented of the relationship between lightning occurrence and fires attributed to lightning ignitions. Lightning occurrence data are matched to a database of fires attributed to lightning ignition over southeastern Australia and are compared with atmospheric and fuel characteristics at the time of the lightning occurrence. Factors influencing the chance of fire per lightning stroke are examined, including the influence of fuel moisture and weather parameters, as well as seasonal and diurnal variations. The fuel moisture parameters of the Canadian Fire Weather Index System are found to be useful in indicating whether a fire will occur, given the occurrence of lightning. The occurrence of “dry lightning” (i.e., lightning that occurs without significant rainfall) is found to have a large influence on the chance of fire per lightning stroke. Through comparison of the results presented here with the results of studies from other parts of the world, a considerable degree of universality is shown to exist in the characteristics of lightning fires and the atmospheric conditions associated with them, suggesting the potential for these results to be applied more widely than just in the area of the study.
U.S. Summer Precipitation and Temperature Patterns Following the Peak Phase of El Niño
Authors: Wang Hui , Kumar Arun , Wang Wanqiu , Jha Bhaskar 
Published: June 2012

Abstract
Evidence for spatially coherent, but different, U.S. summer precipitation and surface air temperature anomalies during the evolving phase and during the summers following the peak phase of the winter El Niño is presented. The spatial patterns during the decaying phase of El Niño are distinctive from patterns in the preceding summer when El Niño is in its evolving phase, that is, the traditional “simultaneous” composite patterns associated with El Niño. The analysis of a multimodel ensemble of global atmospheric models forced by observed sea surface temperature further confirms that the differences in the U.S. summer precipitation and surface temperature anomalies between the developing and decaying phases of El Niño are a result of the atmospheric response to tropical warm SST anomalies that are shifted eastward and are confined east of 120°W during the decaying phase of El Niño. Given the distinctive pattern, and relatively large amplitude of these anomalies during the decaying phase of El Niño, the results may have implications for the seasonal prediction of U.S. summer precipitation and temperature following winter El Niños.
Large-Scale Control on the Patagonian Climate
Authors: Garreaud R. , Lopez P. , Minvielle M. , Rojas M. 
Published: June 2012

Abstract
Patagonia, located in southern South America, is a vast and remote region holding a rich variety of past environmental records but a small number of meteorological stations. Precipitation over this region is mostly produced by disturbances embedded in the westerly flow and is strongly modified by the austral Andes. Uplift on the windward side leads to hyperhumid conditions along the Pacific coast and the western slope of the Andes; in contrast, downslope subsidence dries the eastern plains leading to arid, highly evaporative conditions.
The authors investigate the dependence of Patagonia’s local climate (precipitation and near-surface air temperature) year-to-year variability on large-scale circulation anomalies using results from a 30-yr-long high-resolution numerical simulation. Variations of the low-level zonal wind account for a large fraction of the rainfall variability at synoptic and interannual time scales. Zonal wind also controls the amplitude of the air temperature annual cycle by changing the intensity of the seasonally varying temperature advection.
The main modes of year-to-year variability of the zonal flow over southern South America are also investigated. Year round there is a dipole between mid- and high latitudes. The node separating wind anomalies of opposite sign migrates through the seasons, leading to a dipole over Patagonia during austral summer and a monopole during winter. Reanalysis data also suggests that westerly flow has mostly decreased over north-central Patagonia during the last four decades, causing a drying trend to the west of the Andes, but a modest increase is exhibited over the southern tip of the continent.
Different Evolutions of the Philippine Sea Anticyclone between the Eastern and Central Pacific El Niño: Possible Effects of Indian Ocean SST
Authors: Yuan Yuan , Yang Song , Zhang Zuqiang 
Published: June 2012

AbstractThe authors examine different evolution features of the low-level anticyclone over the tropical northwestern Pacific between eastern Pacific (EP) El Niño events and central Pacific (CP) El Niño events. During EP El Niño, the low-level anticyclone shows an eastward movement from the northern Indian Ocean to the east of the Philippines. During CP El Niño, however, the anticyclone is mostly confined to the west of the Philippines. It is weaker, exhibits a shorter lifetime, and lacks eastward movement compared to the Philippine Sea anticyclone (PSAC) during EP El Niño. Investigation into the possible impact of Indian Ocean (IO) sea surface temperature (SST) on the evolution of the low-level anticyclone during EP and CP El Niño indicates that both SST and low-level atmospheric circulation over the IO are related more strongly with EP El Niño than with CP El Niño. The IO SST tends to exert a more prominent influence on PSAC during EP El Niño than during CP El Niño. During the developing summer and autumn of EP El Niño, the anomalous anticyclone over the northern Indian Ocean excited by positive IO dipole may contribute to an early development of the PSAC. During the winter and decaying spring, the anomalous anticyclone to the east of the Philippines instigated by the IO basin-wide warming mode also favors a larger persistence of the PSAC. During CP El Niño, however, IO SST shows a negligible impact on the evolution of the anticyclone.
A Study on the Synoptic-Dynamical Characteristics of Compact Tropical Cyclones in the Western North Pacific
Authors: Yen-Chu Chen Delia , Cheung Kevin K. W. , Lee Cheng-Shang 
Published: June 2012

Abstract
This study focuses on the synoptic and dynamical characteristic of compact and incompact tropical cyclones (TCs) in the western North Pacific. To identify the distinct mechanisms related to the development and maintenance of these two categories of TCs, the Weather Research and Forecasting Model (WRF) is used to simulate the compact Typhoon Yutu (2007) and the incompact Typhoon Manyi (2007). Simulation results of Yutu show that the wind speed increases primarily in the inner-core region, where strong relative vorticity and high inertial stability is also located. Comparatively, the inertial stability for Typhoon Manyi is much weaker, which makes it more susceptible to influences from external low-level forcing. Diagnoses of the numerical simulations as well as examination of the synoptic environments that embed the two TCs suggest that compact TCs mainly develop through internal dynamics, whereas incompact TCs are usually driven by external forcing. Several sets of sensitivity experiments are designed to determine the relative roles of initial vortex structure, environmental flow, and humidity in subsequent TC structural evolution. Results show that in an environment that favors compact TCs, initial vortex largely determines the later structural development. However, vortex development is quite sensitive to its initial intensity and the radius of maximum wind (RMW) under environmental flow that favors incompact TCs. Results of the experiments on environmental humidity show that a humid environment generates large vortex structural changes in incompact TCs. A relatively dry environment brings minimal impacts to the originally compact TC, but can increase the compactness of the originally incompact ones.
Objective Prediction of Warm Season Afternoon Thunderstorms in Northern Taiwan Using a Fuzzy Logic Approach
Authors: Lin Pin-Fang , Chang Pao-Liang , Jong-Dao Jou Ben , Wilson James W. , Roberts Rita D. 
Published: June 2012

Abstract
In this study, a fuzzy logic algorithm is developed to provide objective guidance for the prediction of afternoon thunderstorms in northern Taiwan using preconvective predictors during the warm season (May–October) from 2005 to 2008. The predictors are derived from surface stations and sounding measurements. The study is limited to 277 days when synoptic forcing was weak and thermal instability produced by the solar heating is primarily responsible for thunderstorm initiation. The fuzzy algorithm contains 29 predictors and associated weights. The weights are based on the maximum of the critical success index (CSI) to forecast afternoon thunderstorms. The most important predictors illustrate that under relatively warm and moist synoptic conditions, sea-breeze transport of moisture into the Taipei Basin along with weak winds inland provide favorable conditions for the occurrence of afternoon convective storms. In addition, persistence of yesterday’s convective storm activity contributed to improving today’s forecast. Skill score comparison between the fuzzy algorithm and forecasters from the Taiwan Central Weather Bureau showed that for forecasting afternoon thunderstorms, the fuzzy logic algorithm outperformed the operational forecasters. This was the case for both the calibration and independent datasets. There was a tendency for the forecasters to overforecast the number of afternoon thunderstorm days. The fuzzy logic algorithm is able to integrate the preconvective predictors and provide probability guidance for the prediction of afternoon thunderstorms under weak synoptic-scale conditions, and could be implemented in real-time operations as a forecaster aid.
A WRF Ensemble for Improved Wind Speed Forecasts at Turbine Height
Authors: Deppe Adam J. , Gallus William A. , Takle Eugene S. 
Published: June 2012

Abstract
The Weather Research and Forecasting Model (WRF) with 10-km horizontal grid spacing was used to explore improvements in wind speed forecasts at a typical wind turbine hub height (80 m). An ensemble consisting of WRF model simulations with different planetary boundary layer (PBL) schemes showed little spread among the individual ensemble members for forecasting wind speed. A second configuration using three random perturbations of the Global Forecast System model produced more spread in the wind speed forecasts, but the ensemble mean possessed a higher mean absolute error (MAE). A third ensemble of different initialization times showed larger model spread, but model MAE was not compromised. In addition, postprocessing techniques such as training of the model for the day 2 forecast based on day 1 results and bias correction based on observed wind direction are examined. Ramp event forecasting was also explored. An event was considered to be a ramp event if the change in wind power was 50% or more of total capacity in either 4 or 2 h or less. This was approximated using a typical wind turbine power curve such that any wind speed increase or decrease of more than 3 m s−1 within the 6–12 m s−1 window (where power production varies greatly) in 4 h or less would be considered a ramp. Model MAE, climatology of ramp events, and causes were examined. All PBL schemes examined predicted fewer ramp events compared to the observations, and model forecasts for ramps in general were poor.