163 research outputs found
Recommended from our members
Apparatus and method for deforming a workpiece
An apparatus and method is provided for controlling the temperature of dies and workpiece throughout a deformation process. Dies are capable of receiving external current to resistively heat the workpiece and dies during the deformation operation, the external current being modulated by feedback temperature readings taken from the workpiece. External current may be provided from a homopolar generator capable of producing pulsed dc current at controllable intervals and magnitudes simultaneously through the dies and workpiece.Board of Regents, University of Texas Syste
Recommended from our members
Method and construction for control of current distribution in railgun armatures
An electromagnetic railgun having a layer of low conductivity material along the rails to interface with the armature as the armature is propelled along the rails. The low conductivity material has been found to permit rapid current penetration between the layer and armature, thereby inhibiting undersirable high current density formation along the trailing edge of the armature. Advantageously, inhibiting the high current density formation permits use of a solid armature at velocities exceeding on kilometer per second. Preferably, the layer is composed of graphite or a graphite/copper mixture. A layer of copper or other high conductivity material is preferably laminated to the low conductivity graphite layer to reduce the overall railgun circuit resistance. In the preferred embodiment, the layer of low conductivity material increases in thickness from the breech to the muzzle to decrease railgun circuit resistance.Board of Regents, University of Texas Syste
Recommended from our members
Method and construction for control of current distribution in railgun armatures
An electromagnetic railgun having a layer of low conductivity material along the rails to interface with the armature as the armature is propelled along the rails. The low conductivity material has been found to permit rapid current penetration between the layer and armature, thereby inhibiting undesirable high current density formation along the trailing edge of the armature. Advantageously, inhibiting the high current density formation permits use of a solid armature at velocities exceeding one kilometer per second. Preferably, the layer is composed of graphite or a graphite/copper mixture. A layer of copper or other high conductivity material is preferably laminated to the low conductivity graphite layer to reduce the overall railgun circuit resistance. In the preferred embodiment, the layer of low conductivity material increases in thickness from the breech to the muzzle to decrease railgun circuit resistance.Board of Regents, University of Texas Syste
Recommended from our members
Staged opening switch
" A staged switch for conducting a large electrical current for an indefinite time period and then rapidly switching the current into a load circuit. The switch comprises a first stage which can conduct a large electrical current for an indefinite time period without damage to the stage and a second stage which is a fast-opening element. The first stage includes primary and secondary contacts wherein the primary contacts conduct a charging current and the secondary contacts divert the current into the fast-opening second stage. The secondary contacts ""make"" before the primary contacts ""break"", reducing the damage to the contacts which might otherwise be experienced. The second stage is a low-inductance element which reduces the level of energy absorbed by the first-stage contacts, minimizing damage to the contacts. The second-stage element may be constructed in a cartridge and may be loaded into the switch using an autoloader device. "Board of Regents, University of Texas Syste
Do SASS5 scores vary with season in the South African highveld? A case study on the Skeerpoort River, North West province, South Africa
Macroinvertebrate assemblages can vary with season as a result of changing environmental
conditions and phenology of individual species. The objective of this study was to determine
whether results from the South African Scoring System version 5 (SASS5) are affected by
season. The standard SASS5 protocol was used to sample three sites on the Skeerpoort River,
South Africa, in autumn, winter and spring 2013, and summer 2014. At each site, stream
morphology was characterised and physicochemical variables were measured. Two-way
analysis of variance (ANOVA) was used to compare SASS indices in relation to site and
season, and a one-way ANOVA was used to test the effect of season using both current and
historical data. Macroinvertebrate assemblage similarity of sites was determined using nonmetric
multidimensional scaling ordination, followed by analysis of similarity. Whilst
macroinvertebrate assemblages differed between seasons and sites, there was no seasonal
variation in the values of SASS indices, but they did differ between sites. SASS5 appears to
be robust to seasonal variation in macroinvertebrate assemblage and seems suitable for use
throughout the year in a perennial river draining the South African highveld region.University of Pretoria through a Research Development Programme.http://www.tandfonline.com/loi/taas202015-12-30hb201
Cold Chain and VirusâFree ChloroplastâMade Booster Vaccine to Confer Immunity Against Different Poliovirus Serotypes
The WHO recommends complete withdrawal of oral polio vaccine (OPV) type 2 by April 2016 globally and replacing with at least one dose of inactivated poliovirus vaccine (IPV). However, highâcost, limited supply of IPV, persistent circulating vaccineâderived polioviruses transmission and need for subsequent boosters remain unresolved. To meet this critical need, a novel strategy of a lowâcost cold chainâfree plantâmade viral protein 1 (VP1) subunit oral booster vaccine after single IPV dose is reported. Codon optimization of the VP1 gene enhanced expression by 50âfold in chloroplasts. Oral boosting of VP1 expressed in plant cells with plantâderived adjuvants after single priming with IPV significantly increased VP1âIgG1 and VP1âIgA titres when compared to lower IgG1 or negligible IgA titres with IPV injections. IgA plays a pivotal role in polio eradication because of its transmission through contaminated water or sewer systems. Neutralizing antibody titres (~3.17â10.17 log2 titre) and seropositivity (70â90%) against all three poliovirus Sabin serotypes were observed with two doses of IPV and plantâcell oral boosters but single dose of IPV resulted in poor neutralization. Lyophilized plant cells expressing VP1 stored at ambient temperature maintained efficacy and preserved antigen folding/assembly indefinitely, thereby eliminating cold chain currently required for all vaccines. Replacement of OPV with this booster vaccine and the next steps in clinical translation of FDAâapproved antigens and adjuvants are discussed
Enhanced Immunogenicity of Stabilized Trimeric Soluble Influenza Hemagglutinin
The recent swine-origin H1N1 pandemic illustrates the need to develop improved procedures for rapid production of influenza vaccines. One alternative to the current egg-based manufacture of influenza vaccine is to produce a hemagglutinin (HA) subunit vaccine using a recombinant expression system with the potential for high protein yields, ease of cloning new antigenic variants, and an established safety record in humans.We generated a soluble HA (sHA), derived from the H3N2 virus A/Aichi/2/68, modified at the C-terminus with a GCN4pII trimerization repeat to stabilize the native trimeric structure of HA. When expressed in the baculovirus system, the modified sHA formed native trimers. In contrast, the unmodified sHA was found to present epitopes recognized by a low-pH conformation specific monoclonal antibody. We found that mice primed and boosted with 3 microg of trimeric sHA in the absence of adjuvants had significantly higher IgG and HAI titers than mice that received the unmodified sHA. This correlated with an increased survival and reduced body weight loss following lethal challenge with mouse-adapted A/Aichi/2/68 virus. In addition, mice receiving a single vaccination of the trimeric sHA in the absence of adjuvants had improved survival and body weight loss compared to mice vaccinated with the unmodified sHA.Our data indicate that the recombinant trimeric sHA presents native trimeric epitopes while the unmodified sHA presents epitopes not exposed in the native HA molecule. The epitopes presented in the unmodified sHA constitute a "silent face" which may skew the antibody response to epitopes not accessible in live virus at neutral pH. The results demonstrate that the trimeric sHA is a more effective influenza vaccine candidate and emphasize the importance of structure-based antigen design in improving recombinant HA vaccines
Recommended from our members
High performance electromagnetic railgun launcher
A railgun operates at high pressure (up to 350 MPa) without structural damage and is readily disassembled for inspection, maintenance and component testing. A rail assembly is pressed into a hoop-wound epoxy fiberglass containment tube and clamped within a steel compression frame. The geometry of the rail assembly permits rail movement without insulator intrusion and achieves bore sealing during rail movement at maximum pressure. The rail assembly also has replaceable insulator inserts which are isolated from rail re-bound shock. Fused quartz insulator inserts provide the best results. A flash tube is provided at the gun muzzle to suppress precursor discharge and commutate precursor current back to the armature. To realize increased velocity without sacrificing in-bore projectile stability, a cut-corner projectile is used having a L/D ratio as small as 0.65 which reduces the mass by about 11%.Board of Regents, University of Texas Syste
Selection on female reproductive schedules in the marula fly, ceratitis cosyra (Diptera : Tephritidae) affects dietary optima for female reproductive traits but not lifespan
DATA AVAILABILITY STATEMENT : The raw data supporting the conclusions of this article will be
made available by the authors, without undue reservation.INTRODUCTION : A changing environment can select on life-history traits and tradeoffs
in a myriad of ways. For example, global warming may shift phenology and
thus the availability of host-plants. This may alter selection on survival and fertility
schedules in herbivorous insects. If selection on life-histories changes, this may
in turn select for altered nutrient intake, because the blend of nutrients
organisms consume helps determine the expression of life-history traits.
However, we lack empirical work testing whether shifts in the timing of
oviposition alter nutrient intake and life-history strategies.
METHODS : We tested in the marula fruit fly, Ceratitis cosyra, how upward-selection
on the age of female oviposition, in comparison with laboratory adapted control
flies, affects the sex-specific relationship between protein and carbohydrate intake
and life-history traits including lifespan, female lifetime egg production and daily
egg production. We then determined the macronutrient ratio consumed when
flies from each selection line and sex were allowed to self-regulate their intake.
RESULTS : Lifespan, lifetime egg production and daily egg production were
optimised at similar protein to carbohydrate (P:C) ratios in flies from both
selection lines. Likewise, females and males of both lines actively defended
similar nutrient intake ratios (control =1:3.6 P:C; upward-selected = 1:3.2 P:C).
DISCUSSION : Our results are comparable to those in non-selected C. cosyra,
where the optima for each trait and the self-selected protein to carbohydrate
ratio observed were nearly identical. The nutrient blend that needs to be ingested for optimal expression of a given trait appeared to be well conserved across
laboratory adapted and experimentally selected populations. These results
suggest that in C. cosyra, nutritional requirements do not respond to a
temporal change in oviposition substrate availability.A National Research Foundation Competitive Programme for Rated Researchers grant and the Australian Research Council.https://www.frontiersin.org/journals/insect-scienceam2024Zoology and EntomologySDG-15:Life on lan
Immunity and field efficacy of type 2-containing polio vaccines after cessation of trivalent oral polio vaccine: A population-based serological study in Pakistan
Background: In Pakistan and other countries using oral polio vaccine (OPV), immunity to type 2 poliovirus is now maintained by a single dose of inactivated polio vaccine (IPV) in routine immunization, supplemented in outbreak settings by monovalent OPV type 2 (mOPV2) and IPV. While well-studied in clinical trials, population protection against poliovirus type 2 achieved in routine and outbreak settings is generally unknown.Methods: We conducted two phases of a population-based serological survey of 7940 children aged 6-11 months old, between November 2016 and October 2017 from 13 polio high-risk locations in Pakistan.Results: Type 2 seroprevalence was 50% among children born after trivalent OPV (tOPV) withdrawal (April 2016), with heterogeneity across survey areas. Supplementary immunization activities (SIAs) with mOPV2 followed by IPV improved population immunity, varying from 89% in Pishin to 64% in Killa Abdullah, with little observed marginal benefit of subsequent campaigns. In the other high-risk districts surveyed, a single SIA with IPV was conducted and appeared to improve immunity to 57% in Karachi to 84% in Khyber.Conclusions: Our study documents declining population immunity following trivalent OPV withdrawal in Pakistan, and wide heterogeneity in the population impact of supplementary immunization campaigns. Differences between areas, attributable to vaccination campaign coverage, were far more important for type 2 humoral immunity than the number of vaccination campaigns or vaccines used. This emphasizes the importance of immunization campaign coverage for type 2 outbreak response in the final stages of polio eradication. Given the declining type 2 immunity in new birth cohorts it is also recommended that 2 or more doses of IPV should be introduced in the routine immunization program of Pakistan
- âŠ