1,433 research outputs found
Plume Contamination Measurements of an Additively-Printed GOX/ABS Hybrid Thruster
This thesis examines the impact of the physical contamination on optical surfaces of spacecraft by an ABS/GOX thruster. Plume contamination presents a significant operational hazard for spacecraft solar arrays and thermal control surfaces can lead to decreased power production and increased spacecraft temperatures. Historically, due to the lack of a reliable, on-demand, and multiple-use ignition methodology, hybrid rockets have never been previously considered for in-space propulsion. Recent advancements in hybrid rocket technologies, have made hybrid systems feasible for in space propulsion. However, prior to this study no research had ever been performed with regard to plume contamination effects due to hybrid rockets. This paper presents the results from a set of preliminary plume contamination measurements on a prototype small spacecraft hybrid rocket system, collected under both ambient and vacuum chamber conditions
Identifying the Overarching Logistics Strategy of Business Practices
In a 'hyper competitive context’ (D'Aveni 1994), a major issue for enterprises is the strategic use of logistics capability to gain create and leverage value in the marketplace. Management is now appreciating that a logistics strategy makes a key contribution to corporate strategy and performance. This paper investigates the extent of complementarity between the logistics strategy and business practices in 20 organisations in the management of their operations, inventory, alliances, customers, supply chain integration, performance assessment, information technology and EDI practices. Non-linear canonical correlation analysis is used to establish the degree of concordance between business practices and the logistic strategy for a sample of Australian organisations involved in freight transportation. The evidence suggests that there is very strong synergy between a logistics strategy and the broader set of business initiatives in transport businesses, giving strong support to the overarching role of logistics strategy. This is in contrast to non-transport organisations where logistics is still seen as a separate activity centre, with the exception of information technology and EDI
Distributed Work and Travel Behaviour: The Dynamics of Interactive Agency Choices between Employers and Employees
This paper develops a framework within which multiple agents make discrete choices in respect of a common objective - the determination of participation in distributed work, especially the opportunities and constraints associated with telecommuting. Ideas in discrete choice theory and game theory are combined to define a set of choice experiments in which employees and employers interact in arriving at a choice path in a distributed work context. A stated choice experiment with offers and feedback, known as an interactive agency choice experiment (IACE), is empirically investigated in the context of telecommuting options with an exploratory sample of employees and employers in Sydney, Australia. The approach highlights the role of information and negotiation in breaking down the barriers to more flexible work activity, to deliver potential benefits to the transport system such as reduced traffic congestion and environmental sustainability. The paper identifies the types of incentives that an employee/er has to offer the employer/employee in securing effective telecommuting
Demonstration of safety of intravenous immunoglobulin in geriatric patients in a long-term, placebo-controlled study of Alzheimer's disease.
INTRODUCTION:We present safety results from a study of Gammagard Liquid intravenous immunoglobulin (IGIV) in patients with probable Alzheimer's disease. METHODS:This was a placebo-controlled double-blind study. Subjects were randomized to 400 mg/kg (n = 127), 200 mg/kg (n = 135) IGIV, or to 0.25% human albumin (n = 121) administered every 2 weeks ± 7 days for 18 months. RESULTS:Elevated risk ratios of IGIV versus placebo included chills (3.85) in 9.5% of IGIV-treated subjects (all doses), compared to 2.5% of placebo-treated subjects, and rash (3.08) in 15.3% of IGIV-treated subjects versus 5.0% of subjects treated with placebo. Subjects in the highest IGIV dose group had the lowest proportion of SAEs considered related to product (2 of 127 [1.6%]). Subjects treated with IGIV experienced a lower rate of respiratory and all other infections compared to placebo. DISCUSSION:IGIV-treated subjects did not experience higher rates of renal failure, lung injury, or thrombotic events than the placebo group. There were no unexpected safety findings. IGIV was well tolerated throughout 18 months of treatment in subjects aged 50-89 years
LC-MS proteomics analysis of the iInsulin/IGF-1-deficient Caenorhabditis elegans daf-2(e1370) mutant reveals extensive restructuring of intermediary metabolism
The insulin/IGF-1 receptor is a major known determinant of dauer formation, stress resistance, longevity, and metabolism in Caenorhabditis elegans. In the past, whole-genome transcript profiling was used extensively to study differential gene expression in response to reduced insulin/IGF-1 signaling, including the expression levels of metabolism-associated genes. Taking advantage of the recent developments in quantitative liquid chromatography mass spectrometry (LC-MS)-based proteomics, we profiled the proteomic changes that occur in response to activation of the DAF-16 transcription factor in the germline-less glp-4(bn2);daf-2(e1370) receptor mutant. Strikingly, the daf-2 profile suggests extensive reorganization of intermediary metabolism, characterized by the upregulation of many core intermediary metabolic pathways. These include glycolysis/gluconeogenesis, glycogenesis, pentose phosphate cycle, citric acid cycle, glyoxylate shunt, fatty acid beta-oxidation, one-carbon metabolism, propionate and tyrosine catabolism, and complexes I, II, III, and V of the electron transport chain. Interestingly, we found simultaneous activation of reciprocally regulated metabolic pathways, which is indicative of spatiotemporal coordination of energy metabolism and/or extensive post-translational regulation of these enzymes. This restructuring of daf-2 metabolism is reminiscent to that of hypometabolic dauers, allowing the efficient and economical utilization of internal nutrient reserves and possibly also shunting metabolites through alternative energy-generating pathways to sustain longevity
The SWELLS survey. IV. Precision measurements of the stellar and dark matter distributions in a spiral lens galaxy
We construct a fully self-consistent mass model for the lens galaxy J2141 at
z=0.14, and use it to improve on previous studies by modelling its
gravitational lensing effect, gas rotation curve and stellar kinematics
simultaneously. We adopt a very flexible axisymmetric mass model constituted by
a generalized NFW dark matter halo and a stellar mass distribution obtained by
deprojecting the MGE fit to the high-resolution K'-band LGSAO imaging data of
the galaxy, with the (spatially constant) M/L ratio as a free parameter. We
model the stellar kinematics by solving the anisotropic Jeans equations. We
find that the inner logarithmic slope of the dark halo is weakly constrained
(gamma = 0.82^{+0.65}_{-0.54}), and consistent with an unmodified NFW profile.
We infer the galaxy to have (i) a dark matter fraction within 2.2 disk radii of
0.28^{+0.15}_{-0.10}, independent of the galaxy stellar population, implying a
maximal disk for J2141; (ii) an apparently uncontracted dark matter halo, with
concentration c_{-2} = 7.7_{-2.5}^{+4.2} and virial velocity v_{vir} =
242_{-39}^{+44} km/s, consistent with LCDM predictions; (iii) a slightly oblate
halo (q_h = 0.75^{+0.27}_{-0.16}), consistent with predictions from
baryon-affected models. Comparing the stellar mass inferred from the combined
analysis (log_{10} Mstar/Msun = 11.12_{-0.09}^{+0.05}) with that inferred from
SPS modelling of the galaxies colours, and accounting for a cold gas fraction
of 20+/-10%, we determine a preference for a Chabrier IMF over Salpeter IMF by
a Bayes factor of 5.7 (substantial evidence). We infer a value beta_{z} = 1 -
sigma^2_{z}/sigma^2_{R} = 0.43_{-0.11}^{+0.08} for the orbital anisotropy
parameter in the meridional plane, in agreement with most studies of local disk
galaxies, and ruling out at 99% CL that the dynamics of this system can be
described by a two-integral distribution function. [Abridged]Comment: Accepted for publication in MNRAS. 17 pages, 9 figure
The Mass of the White Dwarf Companion in the Self-Lensing Binary KOI-3278: Einstein vs. Newton
KOI-3278 is a self-lensing stellar binary consisting of a white-dwarf
secondary orbiting a Sun-like primary star. Kruse and Agol (2014) noticed small
periodic brightenings every 88.18 days in the Kepler photometry and interpreted
these as the result of microlensing by a white dwarf with about 63 of the
mass of the Sun. We obtained two sets of spectra for the primary that allowed
us to derive three sets of spectroscopic estimates for its effective
temperature, surface gravity, and metallicity for the first time. We used these
values to update the Kruse and Agol (2014) Einsteinian microlensing model,
resulting in a revised mass for the white dwarf of . The spectra also allowed us to determine radial velocities and
derive orbital solutions, with good agreement between the two independent data
sets. An independent Newtonian dynamical MCMC model of the combined velocities
yielded a mass for the white dwarf of . The nominal uncertainty for the Newtonian mass is about four times
better than for the Einsteinian, vs. and the difference
between the two mass determinations is . We then present a joint
Einsteinian microlensing and Newtonian radial velocity model for KOI-3278,
which yielded a mass for the white dwarf of . This joint model does not rely on any white dwarf evolutionary
models or assumptions on the white dwarf mass-radius relation. We discuss the
benefits of a joint model of self-lensing binaries, and how future studies of
these systems can provide insight into the mass-radius relation of white
dwarfs.Comment: ApJ Accepted; 22 Pages, 8 Figures, 6 Tables and 4 Supplementary
Table
Field Evaluations of Insecticide Modes of Action Classes for Control of Horn Flies in Nebraska
Insecticides of different Mode of Action (MoA) classes were tested for their ability to reduce horn fly populations on cattle in Nebraska pastures between 2009 and 2016. Macrocyclic lactone products were the most efficacious, reducing horn fly numbers by an average of 93% over ten location years of testing. Organophosphate and pyrethroid MoA products, tested in 7 and 12 location years, reduced fly numbers by 75% and 73%. Classes tested only once were METI (88% reduction) and a combination of organophosphate + pyrethroid (64%)
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