bluuebunny/crossref_metadata_2025_split huggingface dataset:
Streptococcus mitis
Phage-Encoded Adhesins Mediate Attachment to α2-8-Linked Sialic Acid Residues on Platelet Membrane Gangliosides
Authors: Mitchell Jennifer , Sullam Paul M. 
Published: June 2009

ABSTRACT

The direct binding of bacteria to human platelets contributes to the pathogenesis of infective endocarditis. Platelet binding by
Streptococcus mitis
strain SF100 is mediated in part by two bacteriophage-encoded proteins, PblA and PblB. However, the platelet membrane receptor for these adhesins has been unknown. In this study, we demonstrate that these proteins mediate attachment of bacterial cells to sialylated gangliosides on the platelet cell surface. Desialylation of human platelet monolayers reduced adherence of SF100, whereas treatment of the platelets with
N
- or
O
-glycanases did not affect platelet binding. Treatment of platelets with sialidases having different linkage specificities showed that removal of α2-8-linked sialic acids resulted in a marked reduction in bacterial binding. Preincubation of SF100 with ganglioside GD3, a glycolipid containing α2-8-linked sialic acids that is present on platelet membranes, blocked subsequent binding of this strain to these cells. In contrast, GD3 had no effect on the residual binding of platelets by strain PS344, an isogenic Δ
pblA
Δ
pblB
mutant. Preincubating platelets with specific monoclonal antibodies to ganglioside GD3 also inhibited binding of SF100 to platelets, but again, they had no effect on binding by PS344. When the direct binding of
S. mitis
strains SF100 and PS344 to immobilized gangliosides was tested, binding of PS344 to GD3 was reduced by 70% compared to the parent strain. These results indicated that platelet binding by SF100 is mediated by the interaction of PblA and PblB with α2-8-linked sialic acids on ganglioside GD3.
SEMICONDUCTOR NANOSTRUCTURES IN HIGH MAGNETIC FIELDS: RECENT RESULTS AT HFML NIJMEGEN
Authors: CHRISTIANEN PETER C. M. 
Published: June 2009

A short overview of the current experimental facilities at the HFML Nijmegen, including an update on the planned development of a 45 T Hybrid magnet in conjunction with a Free Electron Laser, was presented. That was followed by a brief highlight of recent results on the high field physical properties of semiconductor nanostructures, such as quantum rings1 and dots,2 graphene3,4 and organic nanostructures.5 The majority of the talk was devoted to the investigation of negatively charged excitons (negative trions, two electrons bound to one hole) in semiconductor quantum wells in high magnetic fields. A comprehensive overview of photoluminescence (PL) experiments on GaAs and CdTe quantum wells (QWs) of variable well widths, containing a low density electron gas (2DEG) was presented. Particular interest was given to the magnetic field range where the ground state of negative trions is changing from a singlet (both electrons having opposite spin) to a triplet (parallel electron spins) state. Using polarized magneto-PL (excitation) and reflectivity spectroscopy we have identified (for both GaAs and CdTe QWs) the four typical excitonic peaks, usually denoted as the singlet, dark triplet and bright triplet trion peaks, as well as the neutral exciton peak. All peaks exhibit a pronounced dependence on polarization, 2DEG density and temperature. CdTe QWs exhibit all four peaks at the entire field range used (< 44 T), whereas the dark triplet emission disappears at high fields for GaAs QWs. We have determined the field strength at which the singlet-triplet crossover occurs for all QWs, which allows us to critically compare our experimental results with theoretical predictions. Remarkably, the actual singlet-triplet transition is hidden in GaAs QWs and a narrow (12 nm) CdTe QW. Since the PL emission energy equals the energy difference between the initial (trion) and final (electron) states, the PL lines themselves do not cross at the singlet-triplet crossover as a result of the different Zeeman energies of the final electron states.6 In contrast the cross-over is directly visible in the PL lines of a wide (20 nm) CdTe QW. This behaviour can be readily understood by the dependence of the electron- and hole g -factors on well width and host material. Note from Publisher: This article contains the abstract only.
SPIN-RELATED TRANSPORT AFFECTED BY COMPETITION BETWEEN SPIN-ORBIT INTERACTION AND ZEEMAN EFFECT
Authors: NITTA JUNSAKU 
Published: June 2009

The spin dynamics in solid state systems is governed by the competition between spin-orbit interaction (SOI) and the Zeeman effect. The SOI couples orbital motion of electron spins with an electric field. The Zeeman effect lifts the spin degeneracy in a magnetic field. In InGaAs -based 2DEGs, it is known that the Rashba SOI energy E SOI can be controlled by an electric field applied on the gate electrode.1 In the presence of SOI, weak localization (WL) due to time reversal symmetric interference changes to weak anti-localization (WAL). We have found crossover from WL to WAL by applying the gate voltage in InGaAs 2DEGs. Applying an in-plane magnetic field to the 2DEG does not affect the orbital motion of the electrons, but only modifies the Zeeman spin splitting energy E Z . This allows tuning the ratio between E SOI and E Z very accurately. We have studied how the interplay between SOI and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs -based 2DEGs. From the quantitative analysis of the magnetoconductance, measured in the presence of an in-plane magnetic field, we conclude that this interplay results in a spin-induced breaking of time reversal symmetry (TRS) and in an enhancement of the spin relaxation time. Both effects are due to a partial alignment of the electron spin along the applied magnetic field, and are found to be in excellent agreement with recent theoretical predictions.2 We find that the electron dephasing time saturates when E Z becomes comparable to E SOI . Moreover, we show that the spin-induced electron dephasing time is a universal function of the ratio E Z /E SOI within the experimental accuracy, i.e. it is independent of any details of the quantum well.3 This universal behavior is explained by the recent theory.4 The suppression of WAL is observed by applying in-plane magnetic field because of the enhancement of the spin relaxation time, and this suppression also appears in narrow InGaAs wires since the effective magnetic field direction is confined by wires. In gate fitted narrow wires, the large enhancement of spin relaxation time is obtained when the Rashba SOI is decreased. The spin relaxation time is more than one order longer than that of 2DEG case. This enhancement suggests that the Rashba SOI strength approaches the Dresselhaus SOI strength. We have numerically investigated the angular dependence of in-plane magnetoconductance in disordered wires with both Rashba and Dresselhaus SOIs. A new method is proposed to determine the relative strength of Rashba and Dresselhaus SOI from transport measurements without the need of fitting parameters.5 This in-plane magnetic field measurement provides fruitful information on spin related transport. Note from Publisher: This article contains the abstract only.
PHOTOLUMINESCENCE AND PHOTOLUMINESCENCE EXCITATION SPECTROSCOPY OF SEMICONDUCTING SINGLE WALL CARBON NANOTUBES
Authors: PLENTZ FLÁVIO , RIBEIRO HENRIQUE B. , JORIO ADO , PIMENTA MARCOS A. , FANTINI C. , PERESSINOTTO V. S. T. , FURTADO C. A. , SANTOS A. P. 
Published: June 2009

Since the discovery of single wall carbon nanotubes (SWNT) in 1991, this nanomaterial has received an enormous attention from the nanoscience and nanotechnology community, not only due to the clear prospects for applications such as novel nanoelectronic and nano-optoelectronic devices, but also because this unique one dimensional (1D) system offered a new possibility for the investigation of novel physical phenomena in low dimensions. In 2002 it was demonstrated that photoluminescence (PL) could be observed in suspensions of isolated SWNTs and, later on, that PL could also be observed from individual, suspended SWNTs. Since then, there has been an increasing amount of work directed towards the investigation of the optical properties of semiconducting SWNTs by PL and photoluminescence excitation spectroscopy (PLE), and the use of PL and PLE for the qualitative and quantitative identification of SWNTs species within and ensemble of carbon nanotubes. In 2005 it was shown that the observed optical transitions are associated to 1D excitons and, from the point of view of optical properties, the rich physics of excitons in SWNTs has received much attention. For instance, it is now clear that excitons and exciton-phonon interactions play a major role in the mechanisms responsible for the emission and the absorption of light in SWNTs. Also, the interaction of SWNTs with their vicinity, which includes the interaction with organic and inorganic molecules, and the modifications in the excitonic system caused by changes in the dielectric constant, can be readily investigated by PL and PLE. In this talk we presented an overview of our recent work in the optical spectroscopy of SWNTs.1–3 In particular, we showed some of our results on the investigation of the exciton-phonon interaction in semiconducting SWNTs and on the modifications in the PL and PLE spectra associated to the interactions with its surrounding environment. Note from Publisher: This article contains the abstract only.
Efficient management of idleness in storage systems
Authors: Mi Ningfang , Riska Alma , Zhang Qi , Smirni Evgenia , Riedel Erik 
Published: June 2009

Various activities that intend to enhance performance, reliability, and availability of storage systems are scheduled with low priority and served during idle times. Under such conditions, idleness becomes a valuable “resource” that needs to be efficiently managed. A common approach in system design is to be nonwork conserving by “idle waiting”, that is, delay the scheduling of background jobs to avoid slowing down upcoming foreground tasks.
In this article, we complement “idle waiting” with the “estimation” of background work to be served in every idle interval to effectively manage the trade-off between the performance of foreground and background tasks. As a result, the storage system is better utilized without compromising foreground performance. Our analysis shows that if idle times have low variability, then idle waiting is not necessary. Only if idle times are highly variable does idle waiting become necessary to minimize the impact of background activity on foreground performance. We further show that if there is burstiness in idle intervals, then it is possible to predict accurately the length of incoming idle intervals and use this information to serve more background jobs without affecting foreground performance.
DITPA (3,5-Diiodothyropropionic Acid), a Thyroid Hormone Analog to Treat Heart Failure
Authors: Goldman Steven , McCarren Madeline , Morkin Eugene , Ladenson Paul W. , Edson Robert , Warren Stuart , Ohm Janet , Thai Hoang , Churby Lori , Barnhill Jamie , O'Brien Terrence , Anand Inder , Warner Alberta , Hattler Brack , Dunlap Mark , Erikson John , Shih Mei-Chiung , Lavori Phil 
Published: June 2009

Background—In animal studies and a pilot trial in patients with congestive heart failure, the thyroid hormone analog 3,5 diiodothyropropionic acid (DITPA) had beneficial hemodynamic effects.Methods and Results—This was a phase II multicenter, randomized, placebo-controlled, double-blind trial of New York Heart Association class II to IV congestive heart failure patients randomized (2:1) to DITPA or placebo and treated for 6 months. The study enrolled 86 patients (n=57 to DITPA, n=29 to placebo). The primary objective was to assess the effect of DITPA on a composite congestive heart failure end point that classifies patients as improved, worsened, or unchanged based on symptom changes and morbidity/mortality. DITPA was poorly tolerated, which obscured the interpretation of congestive heart failure-specific effects. Fatigue and gastrointestinal complaints, in particular, were more frequent in the DITPA group. DITPA increased cardiac index (by 18%) and decreased systemic vascular resistance (by 11%), serum cholesterol (−20%), low-density lipoprotein cholesterol (−30%), and body weight (−11 lb). Thyroid-stimulating hormone was suppressed in patients given DITPA, which reflects its thyromimetic effect; however, no symptoms or signs of potential hypothyroidism or thyrotoxicosis were seen.Conclusions—DITPA improved some hemodynamic and metabolic parameters, but there was no evidence for symptomatic benefit in congestive heart failure.
Rosiglitazone Reduces the Development and Rupture of Experimental Aortic Aneurysms
Authors: Jones Alun , Deb Rajdeep , Torsney Evelyn , Howe Franklyn , Dunkley Mathew , Gnaneswaran Yanosha , Gaze David , Nasr Hosaam , Loftus Ian M. , Thompson Mathew M. , Cockerill Gillian W. 
Published: June 2009

Background—Development and rupture of aortic aneurysms involve a combination of complex biological processes. Rosiglitazone, a peroxisome proliferator-activated receptor-γ agonist, has been shown to have a broad spectrum of effects in vivo. The hypothesis that rosiglitazone would reduce aneurysm expansion or rupture was tested in the angiotensin II (Ang II)-induced hypercholesterolemic mouse model.Methods and Results—Apolipoprotein E-deficient mice, 12 months of age, were allocated to 4 groups. Three groups were infused with Ang II (1 μg · min−1· kg−1), and the fourth was infused with saline. Rosiglitazone was given 1 week before infusion and 1 week after infusion. At day 28, aortic size was measured, and tissues were collected for analyses. Both pretreatment and posttreatment with rosiglitazone inhibited the occurrence of fatal rupture (11 of 30 versus 0 of 30 versus 0 of 15;P=0.0013) and reduced maximal dilatation of the aorta (4.6±0.13 versus 2.4±0.48 versus 2.15±0.46 mm2;P<0.0001). Blood glucose, total cholesterol, body weight, and atherosclerosis did not differ between groups. Pretreatment with rosiglitazone inhibited the Ang II-induced expression of angiotensin type 1a Ang II receptor while having no effect on the angiotensin type 2 Ang II receptor, in addition to reducing Ang II-induced expression of E-selectin, tumor necrosis factor-α, and interleukin-6.Conclusions—Pretreatment or posttreatment with RGZ reduced aortic expansion and rupture in this mouse model. Reduction of lesions in animals pretreated with rosiglitazone is concomitant with decreased expression of inflammatory mediators. Further studies are needed to elucidate the precise mechanism.
Initial-Condition Sensitivities and the Predictability of Downslope Winds
Authors: Reinecke Patrick A. , Durran Dale R. 
Published: June 2009

Abstract
The sensitivity of downslope wind forecasts to small changes in initial conditions is explored by using 70-member ensemble simulations of two prototypical windstorms observed during the Terrain-Induced Rotor Experiment (T-REX). The 10 weakest and 10 strongest ensemble members are composited and compared for each event.
In the first case, the 6-h ensemble-mean forecast shows a large-amplitude breaking mountain wave and severe downslope winds. Nevertheless, the forecasts are very sensitive to the initial conditions because the difference in the downslope wind speeds predicted by the strong- and weak-member composites grows to larger than 28 m s−1 over the 6-h forecast. The structure of the synoptic-scale flow one hour prior to the windstorm and during the windstorm is very similar in both the weak- and strong-member composites.
Wave breaking is not a significant factor in the second case, in which the strong winds are generated by a layer of high static stability flowing beneath a layer of weaker mid- and upper-tropospheric stability. In this case, the sensitivity to initial conditions is weaker but still significant. The difference in downslope wind speeds between the weak- and strong-member composites grows to 22 m s−1 over 12 h. During and one hour before the windstorm, the synoptic-scale flow exhibits appreciable differences between the strong- and weak-member composites. Although this case appears to be more predictable than the wave-breaking event, neither case suggests that much confidence should be placed in the intensity of downslope winds forecast 12 or more hours in advance.
Changes in the Global Sulfate Burden due to Perturbations in Global CO2 Concentrations
Authors: Ackerley Duncan , Highwood Eleanor J. , Frame David J. , Booth Ben B. B. 
Published: June 2009

Abstract
A large ensemble of general circulation model (GCM) integrations coupled to a fully interactive sulfur cycle scheme were run on the climateprediction.net platform to investigate the uncertainty in the climate response to sulfate aerosol and carbon dioxide (CO2) forcing. The sulfate burden within the model (and the atmosphere) depends on the balance between formation processes and deposition (wet and dry). The wet removal processes for sulfate aerosol are much faster than dry removal and so any changes in atmospheric circulation, cloud cover, and precipitation will feed back on the sulfate burden. When CO2 is doubled in the Hadley Centre Slab Ocean Model (HadSM3), global mean precipitation increased by 5%; however, the global mean sulfate burden increased by 10%. Despite the global mean increase in precipitation, there were large areas of the model showing decreases in precipitation (and cloud cover) in the Northern Hemisphere during June–August, which reduced wet deposition and allowed the sulfate burden to increase. Further experiments were also undertaken with and without doubling CO2 while including a future anthropogenic sulfur emissions scenario. Doubling CO2 further enhanced the increases in sulfate burden associated with increased anthropogenic sulfur emissions as observed in the doubled CO2-only experiment. The implications are that the climate response to doubling CO2 can influence the amount of sulfate within the atmosphere and, despite increases in global mean precipitation, may act to increase it.
Evaluation of Incremental Improvements to Quantitative Precipitation Estimates in Complex Terrain
Authors: Gourley Jonathan J. , Jorgensen David P. , Matrosov Sergey Y. , Flamig Zachary L. 
Published: June 2009

Abstract
Advanced remote sensing and in situ observing systems employed during the Hydrometeorological Testbed experiment on the American River basin near Sacramento, California, provided a unique opportunity to evaluate correction procedures applied to gap-filling, experimental radar precipitation products in complex terrain. The evaluation highlighted improvements in hourly radar rainfall estimation due to optimizing the parameters in the reflectivity-to-rainfall (Z–R) relation, correcting for the range dependence in estimating R due to the vertical variability in Z in snow and melting-layer regions, and improving low-altitude radar coverage by merging rainfall estimates from two research radars operating at different frequencies and polarization states. This evaluation revealed that although the rainfall product from research radars provided the smallest bias relative to gauge estimates, in terms of the root-mean-square error (with the bias removed) and Pearson correlation coefficient it did not outperform the product from a nearby operational radar that used optimized Z–R relations and was corrected for range dependence. This result was attributed to better low-altitude radar coverage with the operational radar over the upper part of the basin. In these regions, the data from the X-band research radar were not available and the C-band research radar was forced to use higher-elevation angles as a result of nearby terrain and tree blockages, which yielded greater uncertainty in surface rainfall estimates. This study highlights the challenges in siting experimental radars in complex terrain. Last, the corrections developed for research radar products were adapted and applied to an operational radar, thus providing a simple transfer of research findings to operational rainfall products yielding significantly improved skill.
Relating the Drag Coefficient and the Roughness Length over the Sea to the Wavelength of the Peak Waves
Authors: Andreas Edgar L. 
Published: June 2009

Abstract
The standard 10-m reference height for computing the drag coefficient over the sea is admittedly arbitrary. The literature contains occasional suggestions that a scaling length based on the wavelength of the peak waves λp is a more natural reference height. Attempts to confirm this hypothesis must be done carefully, however, because of the potential for fictitious correlation between nondimensional dependent and independent variables. With the DMAJ dataset as an example, this study reviews the issue of fictitious correlation in analyses that use λp/2 as the reference height for evaluating the drag coefficient and that use kp (=2π/λp) as a scale for the roughness length z0. (The DMAJ dataset is a compilation of four individual datasets; D, M, A, and J, respectively, identify the lead authors of the four studies: Donelan, Merzi, Anctil, and Janssen.) This dataset has been used in several previous studies to evaluate the dependence of kpz0 and the drag coefficient evaluated at λp/2 on the nondimensional wave parameter ω* = ωpu*/g. Here ωp is the radian frequency of the peak in the wind–wave spectrum, u* is the friction velocity, and g is the acceleration of gravity. Because the DMAJ dataset does not, however, include independent measurements of λp and ωp, λp had to be inferred from measurements of ωp through the wave dispersion relation. The presence of ωp in both the dependent and independent variables, therefore, exacerbates the fictitious correlation. One conclusion, thus, is that using λp to formulate the drag coefficient and the nondimensional roughness length as functions of a nondimensional variable that includes ωp requires a dataset with independent measurements of λp and ωp.