3,362 research outputs found
Comparisons of wing pressure distribution from flight tests of flush and external orifices for Mach numbers from 0.50 to 0.97
Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results
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Catalase-Containing Silica Particles as Ultrasound-Based Hydrogen Peroxide Sensors to Determine Infected From Noninfected Fluid Collections in Humans.
OBJECTIVE. Hydrogen peroxide (H2O2) plays a key role in neutrophil oxidative defense against infection. Catalase-containing silica nanoshells are nanoparticles that generate O2 microbubbles imaged with ultrasound in the presence of elevated H2O2. We aimed to determine whether ultrasound-detectable O2 microbubbles produced by catalase-containing silica nanoshells can determine whether fluid collections drained from patients are infected. SUBJECTS AND METHODS. During this HIPAA-compliant, institutional review board-approved study, 52 human fluid samples were collected from clinically required image-guided percutaneous drainage procedures. Catalase-containing silica nanoshells were added to the fluid samples during imaging in real time using a Sequoia-512 15L8-S linear transducer (Siemens Healthcare). Production of detectable microbubbles was graded subjectively as negative (noninfected) or positive (infected) with low, moderate, or high confidence by a single observer blinded to all clinical data. The truth standard was microbiology laboratory culture results. Performance characteristics including ROC curves were calculated. RESULTS. Microbubble detection to distinguish infected from noninfected fluids was 84% sensitive and 72% specific and offered negative and positive predictive values of 89% and 64%, respectively. The AUC was 0.79. Six of nine false-positive samples were peritoneal fluid collections that were all collected from patients with decompensated cirrhosis. CONCLUSION. The presence of elevated H2O2 indicated by microbubble formation in the presence of catalase-containing silica nanoshells is sensitive in distinguishing infected from noninfected fluids and offers a relatively high negative predictive value. False-positive cases may result from noninfectious oxidative stress. Catalase-containing silica nanoshells may constitute a novel point-of-care test performed at time of percutaneous drainage, potentially obviating placement of drains into otherwise sterile collections and minimizing risk of secondary infection or other complication
Drag reductions obtained by modifying a box-shaped ground vehicle
A box-shaped ground vehicle was used to simulate the aerodynamic drag of high volume transports, that is, delivery vans, trucks, or motor homes. The coast-down technique was used to define the drag of the original vehicle, having all square corners, and several modifications of the vehicle. Test velocities ranged up to 65 miles per hour, which provided maximum Reynolds numbers of 1 times 10 to the 7th power based on vehicle length. One combination of modifications produced a reduction in aerodynamic drag of 61 percent as compared with the original square-cornered vehicle
Rapid Changes of Potassium Concentration at the Outer Surface of Exposed Single Neurons during Membrane Current Flow
K+-sensitive liquid ion-exchanger microelectrodes are shown to be capable of measuring concentration changes which occur on a millisecond time scale. However, some quaternary ammonium ions, such as tetraethylammonium and acetylcholine, are able to block electrode function when present in concentrations as low as 10-4 to 10-3 M. Changes in extracellular potassium concentration caused by spike activity or voltage clamp pulses of exposed single neurons of the snail Helix pomatia may be measured by these electrodes. Quantitative analysis shows that the total amount of excess potassium found in the vicinity of the cell a short time after a clamp pulse, is in relatively good agreement with the amount of potassium carried by the membrane current
TiB_2 and ZrB_2 diffusion barriers in GaAs Ohmic contact technology
The transition metal diboride compounds, ZrB_2 and TiB_2, interposed between Ni/Ge/Au Ohmic contact metallization on n‐type GaAs wafers and an overlying thick Au contact layer, have been investigated to evaluate their effectiveness in stabilizing the Ohmic contact by limiting the in‐diffusion of Au. All of the metal layers were e‐beam deposited except the ZrB_2 which was rf‐diode sputtered. The barrier layer thicknesses were 50 and 100 nm for the TiB_2 and the ZrB_2, respectively. Postdeposition alloying of the contacts was performed at 400, 425, or 450 °C. Auger electron spectroscopy depth profiling of the resultant Ohmic contacts demonstrates that the barrier layers effectively preclude penetration of Au to the Ohmic contact structure. Specific contact resistivities for such contacts are in the low 10^(−7) Ω cm^2 range; although some degradation of the contact resistivity is observed after long term annealing, the values of resistivities do not exceed 1.5×10^(−6) Ω cm^2 after 92 h at 350 °C
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The association of neutrophil-lymphocyte ratio and lymphocyte-monocyte ratio with 3-month clinical outcome after mechanical thrombectomy following stroke
Background and aim
Neutrophil-lymphocyte ratio (NLR) and lymphocyte-monocyte ratio (LMR) are associated with clinical outcomes in malignancy, cardiovascular disease and stroke. Here we investigate their association with outcome after acute ischaemic stroke treated by mechanical thrombectomy (MT).
Methods
Patients were selected using audit data for MT for acute anterior circulation ischaemic stroke at a UK centre from May 2016–July 2017. Clinical and laboratory data including neutrophil, lymphocyte and monocyte count tested before and 24 h after MT were collected. Poor functional outcome was defined as modified Rankin Scale (mRS) of 3–6 at 3 months. Multivariable logistic regression analyses were performed to explore the relationship of NLR and LMR with functional outcome.
Results
One hundred twenty-one patients (mean age 66.4 ± 16.7, 52% female) were included. Higher NLR (adjusted OR 0.022, 95% CI, 0.009–0.34, p = 0.001) and lower LMR (adjusted OR − 0.093, 95% CI (− 0.175)−(− 0.012), p = 0.025) at 24-h post-MT were significantly associated with poorer functional outcome when controlling for age, baseline NIHSS score, infarct size, presence of good collateral supply, recanalisation and symptomatic intracranial haemorrhage on multivariate logistic regression. Admission NLR or LMR were not significant predictors of mRS at 3 months. The optimal cut-off values of NLR and LMR at 24-h post-MT that best discriminated poor outcome were 5.5 (80% sensitivity and 60% specificity) and 2.0 (80% sensitivity and 50% specificity), respectively on receiver operating characteristic curve analysis.
Conclusion
NLR and LMR tested at 24 h after ictus or intervention may predict 3-month functional outcome
Petrography of a "cryptic" mixed magma system – the Mount Waldo granite, coastal Maine
The Mount Waldo granite (MWG), dated at 371 ± 2 Ma, is typical of the younger Devonian intrusions of the coastal Maine magmatic province. It is a coarse-grained, seriate to porphyritic, biotite ± hornblende, titanite-bearing granite with abundant intermediate to felsic magmatic enclaves and less abundant mafic schlieren.
The MWG contains feldspars of various textures and composition, including abundant plagioclase-mantled K-feldspar (rapakivi texture), boxy and spongy cellular plagioclase, and plagioclase that show An spikes and/or central cores of higher Ca content. In addition, the magmatic enclaves also preserve textural evidence for mixing and hybridization. Specifically, abundant mafic clots, acicular apatite, inherited megacrysts of all the feldspar varieties common in the host granite, and titanite-plagioclase intergrowths are all observed.
Although very little mafic material is observed in the MWG at its present level of erosion, abundant textural evidence suggests that mixing occurred at depth in this intrusion. The thermal, chemical, and physical gradients initiated by the injection of mafic material produced not only the array of mixing textures observed in the MWG but also the large-scale convection needed to distribute these features throughout the pluton including its highest levels.
RÉSUMÉ
Le granite du mont Waldo (GMW), situé à 371±2 Ma, est caractéristique des intrusions récentes du Dévonien de la province magmatique côtière du Maine. Il s'agit d'un granite titanitifère à gros grain, sérié à porphyrique de biotite ± hornblende comportant une abondance d'enclaves magmatiques intermédiaires à felsiques et une abondance moindre de schlierens mafiques.
Le GMW renferme des feldspaths de textures et de compositions diverses, notamment une abondance de feldspath potassique recouvert de plagioclase (texture de rapakiwi), de plagioclase alvéolaire massif et spongieux, et de plagioclase présentant des pics d'An ou des noyaux centraux à teneur supérieure en Ca. De plus, les enclaves magmatiques préservent également une preuve texturale de mélange et d'hybridation. On peut, plus précisément observer la totalité de ces traits : une abondance de grumeaux mafiques, de l'apatite aciculaire, des mégacristaux provenant de tous les types de feldspaths courants dans le granite hôte et des enchevêtrements de titanite-plagioclase.
Même si l'on observe très peu de matières mafiques dans le GMW à son niveau actuel d'érosion, d'abondants indices texturaux permettent de supposer que le mixage est survenu en profondeur dans cette intrusion. Les gradients thermiques, chimiques et physiques obtenus par l'injection de matières mafiques a non seulement produit l'éventail de textures de mélange observé dans le GMW, mais également la convection à grande échelle nécessaire à la distribution de ces caractéristiques dans l'ensemble du pluton ainsi qu'à ses niveaux les plus élevés.
[Traduit par la rédaction
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