Efficacy of long-lasting insecticidal nets in use in Macha, Zambia, against the local Anopheles arabiensis population

<p>Abstract</p> <p>Background</p> <p>The mosquito <it>Anopheles arabiensis </it>is the primary vector of <it>Plasmodium falciparum </it>in Macha, Zambia. A major portion of Zambia's current malaria control programme relies on long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) with insecticides. Currently, the efficacy of these measures against <it>An. arabiensis </it>in Macha is unknown, and previous data has shown that <it>An. arabiensis </it>has continued to feed on human hosts, despite high ITN coverage. It is possible that this could be due to either decreased efficacy of ITNs in used in Macha, or pyrethroid resistance in the vector.</p> <p>Methods</p> <p>F1 offspring of field-collected adult <it>An. arabiensis </it>were tested for insecticide resistance, using CDC bottle bioassays and deltamethrin ITN susceptibility assays. The mosquitoes were characterized for the knock-down resistance (<it>kdr</it>) allele by PCR. LLINs that had been in use for two years in nearby villages were collected and tested for residual deltamethrin concentration and net quality, and were used in bioassays against susceptible colonized <it>Anopheles gambiae </it>s.s. Keele. Additionally, a survey on ITN use and care was conducted among LLIN owners.</p> <p>Results</p> <p>In the F1 <it>An</it>. arabiensis field population, low levels of resistance to DDT and deltamethrin-treated net material were detected by bioassay, although the knock-down resistance (<it>kdr</it>) allele not present in the population. ITN evaluations revealed high variability in residual deltamethrin concentration, quality of the nets, and mosquito mortality in bioassays. Mortality against <it>An. gambiae </it>s.s. in bioassays was correlated with residual deltamethrin concentration, which was dependent upon the number of washes each net had received.</p> <p>Conclusions</p> <p>Proper LLIN care was a strong determinant of LLIN efficacy, indicating that education on the importance of LLIN use and care is key when distributing nets. As there is little insecticide resistance in the local vector population, degradation of LLINs most likely allowed for continued human feeding by <it>An. arabiensis</it>. Continued monitoring and assessment of both the vector population and the efficacy of LLINs in use is necessary in order to appropriately modify vector control operations and prevent the development of pyrethroid resistance.</p

Isometries Homotopic to the Identity

The types of surfaces which admit nontrivial isometries homotopic to the identity are classified up to diffeomorphism. In dimension three this is done for complete manifolds of constant negative curvature. Three-dimensional visibility manifolds that admit nontrivial isometries homotopic to the identity are shown to be diffeomorphic to a product L x RI

The Deep Diffuse Extragalactic Radio Sky at 1.75 GHz

We present a study of diffuse extragalactic radio emission at $1.75\,$GHz from part of the ELAIS-S1 field using the Australia Telescope Compact Array. The resulting mosaic is $2.46\,$deg$^2$, with a roughly constant noise region of $0.61\,$deg$^2$ used for analysis. The image has a beam size of $150 \times60\,$arcsec and instrumental $\langle\sigma_{\rm n}\rangle= (52\pm5)\, \mu$Jy beam$^{-1}$. Using point-source models from the ATLAS survey, we subtract the discrete emission in this field for $S \ge 150\, \mu$Jy beam$^{-1}$. Comparison of the source-subtracted probability distribution, or \pd, with the predicted distribution from unsubtracted discrete emission and noise, yields an excess of $(76 \pm 23) \, \mu$Jy beam$^{-1}$. Taking this as an upper limit on any extended emission we constrain several models of extended source counts, assuming $\Omega_{\rm source} \le 2\,$arcmin. The best-fitting models yield temperatures of the radio background from extended emission of $T_{\rm b}=(10\pm7) \,$mK, giving an upper limit on the total temperature at $1.75\,$GHz of $(73\pm10)\,$mK. Further modelling shows that our data are inconsistent with the reported excess temperature of ARCADE2 to a source-count limit of $1\, \mu$Jy. Our new data close a loop-hole in the previous constraints, because of the possibility of extended emission being resolved out at higher resolution. Additionally, we look at a model of cluster halo emission and two WIMP dark matter annihilation source-count models, and discuss general constraints on any predicted counts from such sources. Finally, we report the derived integral count at $1.4\,$GHz using the deepest discrete count plus our new extended-emission limits, providing numbers that can be used for planning future ultra-deep surveys.Comment: 18 pages, 15 figures, 7 tables, Accepted by MNRA

Planning Flood Control Measures by Digital Computer

The purpose of this study was to develop adequate guidelines whereby those interested in flood control planning would be able to apply a pair of digital computer programs known as the University of Kentucky Flood Control Planning Programs to ease the computational burden of evaluating specific flood control situations. Program II determines the economically optimum combination of channel improvement, land use restriction, and flood proofing for flood damage abatement. Program III also incorporates reservoir storage into the planning process. The Programs are not intended to provide a finished design but rather to select the optimum combination of flood control measures and residual flooding with regard to both time and space. Application of Computer Programs to flood control planning is guided by presenting first a general description of the application process then a detailed description of the input required and the output produced by the Planning Programs. Input was developed and results interpreted to determine the optimum flood control plan for the upper reaches of the North Fork of the Kentucky River near Hazard, Kentucky

Polarized Radio Sources: A Study of Luminosity, Redshift and Infrared Colors

The Dominion Radio Astrophysical Observatory Deep Field polarization study has been matched with the Spitzer Wide-Area Infrared Extragalactic survey of the European Large Area Infrared Space Observatory Survey North 1 field. We have used VLA observations with a total intensity rms of 87 microJy beam^-1 to match SWIRE counterparts to the radio sources. Infrared color analysis of our radio sample shows that the majority of polarized sources are elliptical galaxies with an embedded active galactic nucleus. Using available redshift catalogs, we found 429 radio sources of which 69 are polarized with redshifts in the range of 0.04 < z <3.2. We find no correlation between redshift and percentage polarization for our sample. However, for polarized radio sources, we find a weak correlation between increasing percentage polarization and decreasing luminosity.Comment: 35 pages, 12 figures, accepted for publication in The Astrophysical Journa

Intact flagellar motor of Borrelia burgdorferi revealed by cryo-electron tomography: evidence for stator ring curvature and rotor/C-ring assembly flexion.

The bacterial flagellar motor is a remarkable nanomachine that provides motility through flagellar rotation. Prior structural studies have revealed the stunning complexity of the purified rotor and C-ring assemblies from flagellar motors. In this study, we used high-throughput cryo-electron tomography and image analysis of intact Borrelia burgdorferi to produce a three-dimensional (3-D) model of the in situ flagellar motor without imposing rotational symmetry. Structural details of B. burgdorferi, including a layer of outer surface proteins, were clearly visible in the resulting 3-D reconstructions. By averaging the 3-D images of approximately 1,280 flagellar motors, a approximately 3.5-nm-resolution model of the stator and rotor structures was obtained. flgI transposon mutants lacked a torus-shaped structure attached to the flagellar rod, establishing the structural location of the spirochetal P ring. Treatment of intact organisms with the nonionic detergent NP-40 resulted in dissolution of the outermost portion of the motor structure and the C ring, providing insight into the in situ arrangement of the stator and rotor structures. Structural elements associated with the stator followed the curvature of the cytoplasmic membrane. The rotor and the C ring also exhibited angular flexion, resulting in a slight narrowing of both structures in the direction perpendicular to the cell axis. These results indicate an inherent flexibility in the rotor-stator interaction. The FliG switching and energizing component likely provides much of the flexibility needed to maintain the interaction between the curved stator and the relatively symmetrical rotor/C-ring assembly during flagellar rotation

Improving yield and cane quality through implementation of harvesting best practice-2019 Herbert demonstration

In 2019, the Australian sugarcane industry conducted a month-long demonstration with 12 trials to determine the commercial viability of harvesting best practice. Initiated by a small group of innovative growers and contractors from the Herbert region, the concept of a commercial demonstration sought to determine both agronomic and economic impacts of adopting HBP, including the assessment of possible yield gains without having a detrimental impact on extraneous matter, and economic implication for growers and harvesting contractors arising from revenue and harvesting cost changes. Two Herbert harvesting contractors participated in the demonstration comparing their standard harvesting practices to Sugar Research Australia Harvesting Best Practice (HBP or recommended practice). The results identified an average 4.8 t/ha increase in yield with no additional increase in extraneous matter for the recommended setting. A comprehensive economic analysis was conducted on each of the trials. Detailed harvesting costs and operational information, including machinery, labour, and fuel data, were collected from the respective harvesting operations. Harvesting costs and levies were $37/ha ($0.07/t) higher for the recommended setting due to higher yields, reduced harvester ground speeds and lower extractor fan speeds. Despite the higher harvesting costs, recommended settings obtained significantly higher total revenue ($151/ha, +4.7$114/ha in the adoption of recommended settings (based on a 4.4% higher net revenue calculated as total grower revenue minus harvesting costs and levies). The Herbert demonstrations have proven instrumental in the acceptance of harvesting best practice for the region. The results again confirm that adapting and aligning commercial-scale harvesting practices to crop and paddock conditions have positive impacts on both yield and economic outcomes

Spotted-Fever Group Rickettsia in Dermacentor variabilis, Maryland

Three-hundred ninety-two adult Dermacentor variabilis were collected from six Maryland counties during the spring, summer, and fall of 2002. Infection prevalence for spotted fever group Rickettsia was 3.8%, as determined by polymerase chain reaction. Single strand conformational polymorphism (SSCP) analysis followed by sequencing indicated that all infections represented a single rickettsial taxon, Rickettsia montanensis