The impact of significant input of fine sediment on benthic fauna at tributary junctions: a case study of the Bermejo-Paraguay River confluence, Argentina

This study examines the morphological features, suspended sediment inputs and hydraulic conditions within a large river in association with ecological patterns before and after a tributary confluence. In order to examine these effects, the macroinvertebrate distributions from three reaches of the Paraguay and Bermejo Rivers (Paraguay-Argentina) are investigated. The Bermejo River is a tributary that supplies significant quantities of fine sediment to the Paraguay River, primarily in suspension. Two reaches were examined on the Paraguay River, upstream and downstream of the Bermejo River junction, with the third study reach located on the Bermejo River, upstream of the confluence with the Paraguay River. The results provide clear evidence that a significantly increased loading of fine sediment at a river confluence has effects on the distribution and potential movement of benthic invertebrates in the lotic environment by representing physical barriers at affected sites. These effects may be important at both local and regional scales, and such increases in suspended sediment (especially associated with anthropogenic change) may thus pose a major threat to ecosystem integrity that has been historically underestimated

Magnetic Evolution and Temperature Variation in a Coronal Hole

We have explored the magnetic flux evolution and temperature variation in a coronal-hole region, using Big Bear Solar Observatory (BBSO) deep magnetograms and {\it SOHO}/EIT images observed from 2005 October 10 to 14. For comparison, we also investigated a neighboring quiet region of the Sun. The coronal hole evolved from its mature stage to its disappearance during the observing period. We have obtained the following results: (1) When the coronal hole was well developed on October 10, about 60 % of the magnetic flux was positive. The EUV brightness was 420 counts pixel$^{-1}$, and the coronal temperature, estimated from the line ratio of the EIT 195 {\AA} and 171 {\AA} images, was 1.07 MK. (2) On October 14, when the coronal hole had almost disappeared, 51 % of the magnetic flux was positive, the EUV radiance was 530 counts pixel$^{-1}$, and the temperature was 1.10 MK. (3) In the neighboring quiet region, the fraction of positive flux varied between 0.49 and 0.47. The EUV brightness displayed an irregular variation, with a mean value of 870 counts pixel$^{-1}$. The temperature was almost constant at 1.11 MK during the five-day observation. Our results demonstrate that in a coronal hole less imbalance of the magnetic flux in opposite polarities leads to stronger EUV brightness and higher coronal temperatures

In vitro selection of resistance in Streptococcus pneumoniae at in vivo fluoroquinolone concentrations

Methods: Twenty strains of S. pneumoniae susceptible to fluoroquinolones were used. The frequencies of spontaneous single-step mutations at plasma and epithelial lining fluid (ELF) peak and trough antibiotic concentrations were calculated. Multi-step selection of resistance was evaluated by performing 10 serial subcultures on agar plates containing a linear gradient from peak to trough antimicrobial concentrations, followed by 10 subcultures on antibiotic-free agar. Resistant strains selected after multi-step selection were characterized for DNA mutations by sequencing gyrA, gyrB, parC and parE genes. Results: Levofloxacin and moxifloxacin showed the lowest frequencies of mutations (median <10 211 ) at plasma peak and at ELF concentrations, while medians ranging from 10 28 to 10 26 were observed for ciprofloxacin and prulifloxacin. In a multi-step selection assay, ciprofloxacin and prulifloxacin selected for the highest number of resistant strains (19 and 31, respectively). No selection of resistance was observed for levofloxacin at ELF concentrations and for moxifloxacin at plasma and ELF concentrations. Mutations in parC, parE and gyrA genes were found in ciprofloxacin- and prulifloxacinresistant strains, while only parC mutations were found for levofloxacin. Conclusions: Levofloxacin and moxifloxacin are characterized by a lower propensity to select in vitro for resistance in S. pneumoniae than ciprofloxacin and prulifloxacin, when tested at plasma and lung concentrations

Effectiveness evaluation of STOL transport operations

A short-takeoff and landing (STOL) systems simulation model has been developed and implemented in a computer code (known as STOL OPS) which permits evaluation of the operation of a STOL aircraft and its avionics in a commercial airline operating environment. STOL OPS concentrated on the avionics functions of navigation, guidance, control, communication, hazard aviodance, and systems management. External world factors influencing the operation of the STOL aircraft include each airport and its geometry, air traffic at each airport, air traffic control equipment and procedures, weather (including winds and visibility), and the flight path between each airport served by the route. The development of the STOL OPS program provides NASA a set of computer programs which can be used for detailed analysis of a STOL aircraft and its avionics and permit establishment of system requirements as a function of airline mission performance goals

Development of polymer-based nanoparticles for Zileuton delivery to the lung : PMeOx and PMeOzi surface chemistry reduces interactions with mucins

In this paper, two amphiphilic graft copolymers were synthesized by grafting polylactic acid (PLA) as hydrophobic chain and poly(2-methyl-2-oxazoline) (PMeOx) or poly(2-methyl-2-oxazine) (PMeOzi) as hydrophilic chain, respectively, to a backbone of α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). These original graft copolymers were used to prepare nanoparticles delivering Zileuton in inhalation therapy. Among various tested methods, direct nanoprecipitation proved to be the best technique to prepare nanoparticles with the smallest dimensions, the narrowest dimensional distribution and a spherical shape. To overcome the size limitations for administration by inhalation, the nano-into-micro strategy was applied, encapsulating the nanoparticles in water-soluble mannitol-based microparticles by spray-drying. This process has allowed to produce spherical microparticles with the proper size for optimal lung deposition, and, once in contact with fluids mimicking the lung district, able to dissolve and release non-aggregated nanoparticles, potentially able to spread through the mucus, releasing about 70% of the drug payload in 24hours.Peer reviewe

Hydrodynamic and morphologic effects on the benthic invertebrate ecology along a meander bend of a large river (Paraguay River, Argentina-Paraguay)

A detailed hydro-ecological study to identify the effects of bed flow and morphodynamic processes on the distribution (and composition) of benthic invertebrates in a large river is presented herein. A crossing-pool sequence in a meander bend of the Paraguay River (Paraguay-Argentina) was examined. According to the results, there is a link between the benthic fauna, hydraulic and bed sediment size along the bend. The meander pool, with a deep scour hole and the largest bed shear stresses, would be a hostile area for benthic invertebrates, since lower densities were found there. A transversal analysis revealed two different invertebrate assemblages at each of the sampled cross sections: one across the mobile bottom with higher densities but lower diversity, richness and evenness than the other one found close to the banks. On the other hand, a comparison between both Paraguay and Paraná rivers revealed that the first one would seem to have optimal hydraulic conditions for the invertebrate's development, because the hydraulic energy of the Paraná River was too intense for the favorable settlement of benthic organisms at some specific habitats. The overall conclusion of this paper, that morpho-hydraulic features and biotopes are related, is an important step forward in river ecohydrology. With further development of this concept, river management techniques can improve and river rehabilitation projects can be designed with greater confidence.Fil: Blettler, Martin Cesar Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Amsler, Mario Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Ezcurra de Drago, Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Drago, Edmundo Carlos E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Paira, Aldo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Espínola, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Dispelling the myths of online education: learning via the information superhighway

There continues to be a perception that online education is inferior to traditional education. In the U.S. online learning is more developed than in the U.K. This paper provides insights into a U.S. provision and takes a close look at what are perceived as weaknesses of on line learning and argues that these are not necessarily inherent weaknesses of this form of educational delivery. Then, results of two major studies, undertaken in the U.S. are provided comparing the effectiveness of online education to traditional education as perceived by current MBA students and past graduates. Results of these studies suggest that students of MBA modules and MBA graduates perceive the quality and effectiveness of online education to be similar to, if not higher than, the quality and effectiveness of traditional modules and programmes