196,743 research outputs found
Modeling deformation associated with the 2004-2008 dome-building eruption of Mount St. Helens
No full text: Analysis of GPS-measured deformation before, during, and after the 2004-2008 dome-building eruption of Mount St. Helens, Washington
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Mass addition at Mount St. Helens, Washington, inferred from repeated gravity surveys.
No full textRelative gravity measurements were made at 12 sites on Mount St. Helens and 4 sites far afield during the summers of 2010, 2012, 2014, and 2016. Positive residual gravity changes of 0.05–0.06 ± 0.01 mGal from 2010 to 2016—a sign of mass addition—remain at proximal sites after accounting for the effects of changes in Crater Glacier shape and mass. Modeling of the 2010–2016 monitoring data indicates mass addition in the volcano magma reservoir, the volcano conduit, and/or the shallow hydrothermal aquifer. Magma intrusion in the volcano's known reservoir is suggested by the joint inversion of GPS and gravity data (d = 5800 ± 710 m below sea level, ΔVm = 49.8 ± 8.6 × 106m3, ρ = 1930 ± 300 kg/m3); the modeled depth and location are consistent with that of the reservoir that fed the 2004–2008 eruption, and its mass change can explain up to 19% of the residual gravity. The other two potential sources—the conduit and shallow aquifer—are not well constrained. Magma addition along the volcano conduit can explain up to 62% of the residual gravity (ΔVm ≅ 31 × 106m3, ρm ≅ 2, 300 kg/m3). However, such an intrusion should have produced a measurable surface deformation, which is not observed in the GPS time series. Changes in the level of the volcano's shallow hydrothermal system (ρw = 1, 000 kg/m3) can explain 17% (ΔVrecharge ≅ 9 × 106m3) to 61% (ΔVrecharge ≅ 30 × 106m3) of the residual gravity. It would therefore seem that the bulk of the mass change measured at Mount St. Helens during 2010–2016 was caused by shallow accumulation of water beneath the floor of the crater
Single intravenous and oral pharmacokinetics of danofloxacin in the goat
No full textRespiratory diseases including pneumonia are a common concern in goats, with M. Haemolytica the usual causative organism. Owing to danofloxacin's wide spectrum of activity, it is used to treat such disease in goats. The aim of the present study was to investigate danofloxacin pharmacokinetics in the goat after single intravenous (IV) and oral (PO) administration. Sixteen healthy goats were randomly divided into two groups. The first group (n = 8) was administered danofloxacin IV (6 mg/kg) and the second group (n = 8) was administered danofloxacin PO (12 mg/kg). Blood was collected from 0 to 36 h after drug administration. Plasma samples were analyzed for danofloxacin content using a validated HPLC-FL method. The pharmacokinetic analysis was performed using a non-compartmental model, and the PK/PD index was used to predict the antimicrobial effect of danofloxacin. Danofloxacin was quantifiable up to 36 h for both administration routes. After IV administration, danofloxacin demonstrated a long t1/2kel (10.09 h), with a Cl of 0.69 mL/g*h and a Vss of 2.66 mL/g. Unfortunately, an unanticipated long-lasting absorption phase after PO administration only allowed calculation of Cmax (0.13 μg/mL), Tmax (8 h) and AUC(0-t) (2.74 h). The PK/PD surrogate for the prediction of a fluoroquinolone's efficacy (AUC(0–24)/MIC), corrected for danofloxacin's low plasma protein binding, suggested that a single PO danofloxacin dose at 12 mg/kg may be effective against M. haemolytica in the goat
Pharmacokinetics of ivermectin after oral and intravenous administration in Biłgorajska geese (Anser anser domesticus)
No full textAims To assess the pharmacokinetic profile of ivermectin in Bilgorajska geese (Anser anser domesticus) after single I/V or oral administration, in order to compare these routes of administration and assess oral bioavailability. Methods Ten healthy male geese were used in a single-dose, two-phase study with a 3-month washout period between phases. In the first phase, all geese were given 0.2 mg/kg I/V ivermectin, while in the second phase they were treated orally with the same dosage. Blood samples were collected at selected time points up to 480 hours after each administration. Samples were purified using protein precipitation and drug concentration was quantified using HPLC. The analytical method was validated on blank goose plasma and was characterised by an optimal linearity and a limit of quantification of 0.025 mu g/mL. The pharmacokinetic analysis was carried out using a non-compartmental approach. Results The drug was quantifiable up to 240 hours after I/V administration, while after oral treatment it was quantifiable up to 144 hours in most of the geese. The elimination half-life of ivermectin was approximately 3.8 (95% CI = 1.98-7.92; p = 0.027) times higher after I/V administration compared to oral administration. Moreover, the area under the curve from zero to the last detectable timepoint was 6.4 (95% CI = 4.65-8.74; p < 0.001) hours greater after I/V than oral administration. This difference led to a bioavailability of 20.38 (SD 5.92) %. Conclusions Following oral administration in geese, ivermectin has a bioavailability of approximately 20%. Further research on the action of ivermectin in the gastrointestinal tract is required along with assessment of tissue residues to allow calculation of withdrawal time to ensure consumer safety
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Stepping molecular motor amid Lévy white noise
No full textWe consider a model of a stepping molecular motor consisting of two connected heads. Directional motion of the stepper takes place along a one-dimensional track. Each head is subject to a periodic potential without spatial reflection symmetry. When the potential for one head is switched on, it is switched off for the other head. Additionally, the system is subject to the influence of symmetric, white Lévy noise that mimics the action of external random forcing. The stepper exhibits motion with a preferred direction which is examined by analyzing the median of the displacement of a midpoint between the positions of the two heads. We study the modified dynamics of the stepper by numerical simulations. We find flux reversals as noise parameters are changed. Speed and direction appear to very sensitively depend on characteristics of the noise
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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