Predicting Resistance and Stability of Vegetation in Floodplains

To calculate flow or depth in a waterway, it is necessary to accurately determine the flow resistance. Past research has made considerable progress in predicting the roughness of nonvegetated uniform channels based on both theoretical and experimental investigations. However, to determine the flow resistance associated with vegetated compound flow channels and floodplains, the effects of the vegetation must be considered. Recent advancements have led to greater understanding of the effects of partially submerged uniform vegetation in a waterway. However, to accurately determine flow resistance, it is imperative that the effects of both submerged and partially submerged vegetation be taken into account. It is also critical to account for the effects of multiple species and densities of vegetation throughout the waterway. Extensive testing of both partially submerged and fully submerged vegetation was completed in the laboratory. Multiple species were tested together to represent various ecosystems commonly found in floodplains throughout the country. Results of the testing show that both geometric and biomechanical properties of the plants must be accounted for when determining vegetation resistance. Methods and procedures were developed to quantify these properties. Equations were also developed that provide a basis by which to quantify vegetation resistance. The results of this study were compared to several sets of actual field data. The resistance values predicted by the equations were very close to those measured in the field. Use of the developed equations and procedures now provides those involved in the field of flood control a far more accurate tool by which to predict vegetation resistance than was previously available

Management Strategies for Improving the Re-Breeding of the Cow

What are the primary factors that influence the ability of cows to rebreed following calving? From a broad perspective, two key factors influence when conception occurs. First, cows must initiate estrous (heat) cycles following calving to provide the proper conditions for conception to be possible. Secondly those events involved in conception must occur. We will discuss what has to occur before estrous cycles are initiated. The influence of the presence of bulls on initiation of estrous cycles is emphasized. In the second section of the paper, we describe conception rates in 2 and 3 year old cows during the early post calving period. In addition, we describe management decisions which influence net income in cow/calf operations

Management Strategies for Improving the Re-Breeding of the Cow

What are the primary factors that influence the ability of cows to rebreed following calving? From a broad perspective, two key factors influence when conception occurs. First, cows must initiate estrous (heat) cycles following calving to provide the proper conditions for conception to be possible. Secondly those events involved in conception must occur. We will discuss what has to occur before estrous cycles are initiated. The influence of the presence of bulls on initiation of estrous cycles is emphasized. In the second section of the paper, we describe conception rates in 2 and 3 year old cows during the early post calving period. In addition, we describe management decisions which influence net income in cow/calf operations

Routing Games over Time with FIFO policy

We study atomic routing games where every agent travels both along its decided edges and through time. The agents arriving on an edge are first lined up in a \emph{first-in-first-out} queue and may wait: an edge is associated with a capacity, which defines how many agents-per-time-step can pop from the queue's head and enter the edge, to transit for a fixed delay. We show that the best-response optimization problem is not approximable, and that deciding the existence of a Nash equilibrium is complete for the second level of the polynomial hierarchy. Then, we drop the rationality assumption, introduce a behavioral concept based on GPS navigation, and study its worst-case efficiency ratio to coordination.Comment: Submission to WINE-2017 Deadline was August 2nd AoE, 201

Comparison of Upscaled Models for Multistage Mass Discharge from DNAPL Source Zones

Analytical upscaled models that can describe the depletion of dense nonaqueous phase liquids (DNAPLs) and the associated mass discharge are a practical alternative to computationally demanding and data-intensive multiphase numerical simulators. A major shortcoming of most existing upscaled models is that they cannot reproduce the nonmonotonic, multistage effluent concentrations often observed in experiments and numerical simulations. Upscaled models that can produce multistage concentrations either require calibration, which increases the cost of applying them in the field, or use dual-domain conceptual models that may not apply for spatially complex source zones. In this study, a new upscaled model is presented that can describe the nonmonotonic, multistage average concentrations emanating from complex DNAPL source zones. This is achieved by explicitly considering the temporal evolution of three source zone parameters, namely source zone projected area, the average of local-scale DNAPL saturations, and the average of local-scale aqueous relative permeability, without using empirical parameters. The model is evaluated for two real and twelve hypothetical centimeter-scale complex source zones. The proposed model captures the temporal variations in concentrations better than an empirical model and a dual-domain ganglia- to-pool ratio model. The results provide evidence that effluent concentrations downgradient of DNAPL source zones are controlled by the evolution of the aforementioned macroscopic parameters. This knowledge can be useful for the interpretation of field observations of effluent concentrations downstream of DNAPL source zones, and for the development of predictive upscaled models. Advances in DNAPL characterization techniques are needed to quantify these macroscopic parameters that can be used to guide DNAPL remediation efforts

A Three Dimensional Lattice of Ion Traps

We propose an ion trap configuration such that individual traps can be stacked together in a three dimensional simple cubic arrangement. The isolated trap as well as the extended array of ion traps are characterized for different locations in the lattice, illustrating the robustness of the lattice of traps concept. Ease in the addressing of ions at each lattice site, individually or simultaneously, makes this system naturally suitable for a number of experiments. Application of this trap to precision spectroscopy, quantum information processing and the study of few particle interacting system are discussed.Comment: 4 pages, 4 Figures. Fig 1 appears as a composite of 1a, 1b, 1c and 1d. Fig 2 appears as a composite of 2a, 2b and 2

Evaluation of the Novel Combination of High-Dose Daptomycin plus Trimethoprim-Sulfamethoxazole against Daptomycin-Nonsusceptible Methicillin-Resistant Staphylococcus aureus Using an In Vitro Pharmacokinetic/Pharmacodynamic Model of Simulated Endocardial Vegetations

Daptomycin-nonsusceptible (DNS) Staphylococcus aureus is found in difficult-to-treat infections, and the optimal therapy is unknown. We investigated the activity of high-dose (HD) daptomycin plus trimethoprim-sulfamethoxazole de-escalated to HD daptomycin or trimethoprim-sulfamethoxazole against 4 clinical DNS methicillin-resistant S. aureus (MRSA) isolates in an in vitro pharmacokinetic/pharmacodynamic model of simulated endocardial vegetations (109 CFU/g). Simulated regimens included HD daptomycin at 10 mg/kg/day for 14 days, trimethoprim-sulfamethoxazole at 160/800 mg every 12 h for 14 days, HD daptomycin plus trimethoprim-sulfamethoxazole for 14 days, and the combination for 7 days de-escalated to HD daptomycin for 7 days and de-escalated to trimethoprim-sulfamethoxazole for 7 days. Differences in CFU/g (at 168 and 336 h) were evaluated by analysis of variance (ANOVA) with a Tukey's post hoc test. Daptomycin MICs were 4 μg/ml (SA H9749-1, vancomycin-intermediate Staphylococcus aureus; R6212, heteroresistant vancomycin-intermediate Staphylococcus aureus) and 2 μg/ml (R5599 and R5563). Trimethoprim-sulfamethoxazole MICs were ≤0.06/1.19 μg/ml. HD daptomycin plus trimethoprim-sulfamethoxazole displayed rapid bactericidal activity against SA H9749-1 (at 7 h) and R6212 (at 6 h) and bactericidal activity against R5599 (at 72 h) and R5563 (at 36 h). A ≥8 log10 CFU/g decrease was observed with HD daptomycin plus trimethoprim-sulfamethoxazole against all strains (at 48 to 144 h), which was maintained with de-escalation to HD daptomycin or trimethoprim-sulfamethoxazole at 336 h. The combination for 14 days and the combination for 7 days de-escalated to HD daptomycin or trimethoprim-sulfamethoxazole was significantly better than daptomycin monotherapy (P < 0.05) and trimethoprim-sulfamethoxazole monotherapy (P < 0.05) at 168 and 336 h. Combination therapy followed by de-escalation offers a novel bactericidal therapeutic alternative for high-inoculum, serious DNS MRSA infections.We are grateful to St. Joseph’s Hospital Center, Syracuse, NY, for SA H9749-1 and to Albany Medical Center for R5599. This work was funded by an investigator-initiated grant from Cubist Pharmaceuticals. M.J.R. has received grant support, consulted for, or provided lectures for Astellas, Cubist, Forest, Clinical Therapeutics, and Rib-X and is supported in part by grant R21AI092055 for the NIAID

Terahertz frequency standard based on three-photon coherent population trapping

A scheme for a THz frequency standard based on three-photon coherent population trapping in stored ions is proposed. Assuming the propagation directions of the three lasers obey the phase matching condition, we show that stability of few 10$^{-14}$ at one second can be reached with a precision limited by power broadening to $10^{-11}$ in the less favorable case. The referenced THz signal can be propagated over long distances, the useful information being carried by the relative frequency of the three optical photons.Comment: article soumis a PRL le 21 mars 2007, accepte le 10 mai, version 2 (24/05/2007

Evaluation of Ceftaroline Activity against Heteroresistant Vancomycin-Intermediate Staphylococcus aureus and Vancomycin-Intermediate Methicillin-Resistant S. aureus Strains in an In Vitro Pharmacokinetic/Pharmacodynamic Model: Exploring the “Seesaw Effect”

A “seesaw effect” in methicillin-resistant Staphylococcus aureus (MRSA) has been demonstrated, whereby susceptibility to β-lactam antimicrobials increases as glyco- and lipopeptide susceptibility decreases. We investigated this effect by evaluating the activity of the anti-MRSA cephalosporin ceftaroline against isogenic pairs of MRSA strains with various susceptibilities to vancomycin in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model. The activities of ceftaroline at 600 mg every 12 h (q12h) (targeted free maximum concentration of drug in serum [fCmax], 15.2 μg/ml; half-life [t1/2], 2.3 h) and vancomycin at 1 g q12h (targeted fCmax, 18 μg/ml; t1/2, 6 h) were evaluated against 3 pairs of isogenic clinical strains of MRSA that developed increased MICs to vancomycin in patients while on therapy using a two-compartment hollow-fiber PK/PD model with a starting inoculum of ∼107 CFU/ml over a 96-h period. Bacterial killing and development of resistance were evaluated. Expression of penicillin-binding proteins (PBPs) 2 and 4 was evaluated by reverse transcription (RT)-PCR. The achieved pharmacokinetic parameters were 98 to 119% of the targeted values. Ceftaroline and vancomycin were bactericidal against 5/6 and 1/6 strains, respectively, at 96 h. Ceftaroline was more active against the mutant strains than the parent strains, with this difference being statistically significant for 2/3 strain pairs at 96 h. The level of PBP2 expression was 4.4× higher in the vancomycin-intermediate S. aureus (VISA) strain in 1/3 pairs. The levels of PBP2 and PBP4 expression were otherwise similar between the parent and mutant strains. These data support the seesaw hypothesis that ceftaroline, like traditional β-lactams, is more active against strains that are less susceptible to vancomycin even when the ceftaroline MICs are identical. Further research to explore these unique findings is warranted.This work was funded by an investigator-initiated grant from Forest Laboratories. M.J.R. is funded in part by NIH R21A1092055-01. We thank Abbott Laboratories for the use of the fluorescence polarization immunoassay analyzer for determination of vancomycin concentrations. We also thank Alexander Tomasz (The Rockefeller University, New York, NY) for providing strains JH-1 and JH-9. M.J.R. has received grant support, consulted for, or provided lectures for Astellas, Cubist, Forest, Pfizer, Novartis, and Rib-X. B.J.W., M.E.S., and G.W.K. have no potential conflicts of interest to declare