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Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction
The activation energy of a high melting temperature sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the High Pressure Spark Plasma Sintering (HPSPS) technique to 300 and 400 C to produce pellets with dimensions of 5 mm diameter by 1.5 mm height. A custom built ignition setup was developed to measure ignition temperatures at high heating rates (500-2000 C {center_dot} min{sup -1}). Such heating rates were required in order to ignite the thermite composite. Unlike the 400 C samples, results show that the samples consolidated to 300 C undergo an abrupt change in temperature response prior to ignition. This change in temperature response has been attributed to the crystallization of the amorphous WO{sub 3} in the SG derived Ta-WO{sub 3} thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO{sub 3} thermite ranged from approximately 465-670 C. The activation energy of the SG derived Ta-WO{sup 3} thermite composite consolidated to 300 and 400 C were determined to be 37.787 {+-} 1.58 kJ {center_dot} mol{sup -1} and 57.381 {+-} 2.26 kJ {center_dot} mol{sup -1}, respectively
Nucleotide Sequence of a cDNA for a P2 60S Acidic Ribosomal Protein from Parthenium argentatum
Constraining the S factor of 15N(p,g)16O at Astrophysical Energies
The 15N(p,g)16O reaction represents a break out reaction linking the first
and second cycle of the CNO cycles redistributing the carbon and nitrogen
abundances into the oxygen range. The reaction is dominated by two broad
resonances at Ep = 338 keV and 1028 keV and a Direct Capture contribution to
the ground state of 16O. Interference effects between these contributions in
both the low energy region (Ep < 338 keV) and in between the two resonances
(338 <Ep < 1028 keV) can dramatically effect the extrapolation to energies of
astrophysical interest. To facilitate a reliable extrapolation the 15N(p,g)16O
reaction has been remeasured covering the energy range from Ep=1800 keV down to
130 keV. The results have been analyzed in the framework of a multi-level
R-matrix theory and a S(0) value of 39.6 keV b has been found.Comment: 15 pages, 9 figure
Autonomous Medical Needle Steering In Vivo
The use of needles to access sites within organs is fundamental to many
interventional medical procedures both for diagnosis and treatment. Safe and
accurate navigation of a needle through living tissue to an intra-tissue target
is currently often challenging or infeasible due to the presence of anatomical
obstacles in the tissue, high levels of uncertainty, and natural tissue motion
(e.g., due to breathing). Medical robots capable of automating needle-based
procedures in vivo have the potential to overcome these challenges and enable
an enhanced level of patient care and safety. In this paper, we show the first
medical robot that autonomously navigates a needle inside living tissue around
anatomical obstacles to an intra-tissue target. Our system leverages an aiming
device and a laser-patterned highly flexible steerable needle, a type of needle
capable of maneuvering along curvilinear trajectories to avoid obstacles. The
autonomous robot accounts for anatomical obstacles and uncertainty in living
tissue/needle interaction with replanning and control and accounts for
respiratory motion by defining safe insertion time windows during the breathing
cycle. We apply the system to lung biopsy, which is critical in the diagnosis
of lung cancer, the leading cause of cancer-related death in the United States.
We demonstrate successful performance of our system in multiple in vivo porcine
studies and also demonstrate that our approach leveraging autonomous needle
steering outperforms a standard manual clinical technique for lung nodule
access.Comment: 22 pages, 6 figure
Cellular and humoral immune responses and protection against schistosomes induced by a radiation-attenuated vaccine in chimpanzees
The radiation-attenuated Schistosoma mansoni vaccine is highly effective in rodents and primates but has never been tested in humans, primarily for safety reasons. To strengthen its status as a paradigm for a human recombinant antigen vaccine, we have undertaken a small-scale vaccination and challenge experiment in chimpanzees (Pan troglodytes). Immunological, clinical, and parasitological parameters were measured in three animals after multiple vaccinations, together with three controls, during the acute and chronic stages of challenge infection up to chemotherapeutic cure. Vaccination induced a strong in vitro proliferative response and early gamma interferon production, but type 2 cytokines were dominant by the time of challenge. The controls showed little response to challenge infection before the acute stage of the disease, initiated by egg deposition. In contrast, the responses of vaccinated animals were muted throughout the challenge period. Vaccination also induced parasite-specific immunoglobulin M (IgM) and IgG, which reached high levels at the time of challenge, while in control animals levels did not rise markedly before egg deposition. The protective effects of vaccination were manifested as an amelioration of acute disease and overall morbidity, revealed by differences in gamma-glutamyl transferase level, leukocytosis, eosinophilia, and hematocrit. Moreover, vaccinated chimpanzees had a 46% lower level of circulating cathodic antigen and a 38% reduction in fecal egg output, compared to controls, during the chronic phase of infection
The Role of Individual Variables, Organizational Variables and Moral Intensity Dimensions in Libyan Management Accountantsβ Ethical Decision Making
This study investigates the association of a broad set of variables with the ethical decision making of management accountants in Libya. Adopting a cross-sectional methodology, a questionnaire including four different ethical scenarios was used to gather data from 229 participants. For each scenario, ethical decision making was examined in terms of the recognition, judgment and intention stages of Restβs model. A significant relationship was found between ethical recognition and ethical judgment and also between ethical judgment and ethical intention, but ethical recognition did not significantly predict ethical intentionβthus providing support for Restβs model. Organizational variables, age and educational level yielded few significant results. The lack of significance for codes of ethics might reflect their relative lack of development in Libya, in which case Libyan companies should pay attention to their content and how they are supported, especially in the light of the under-development of the accounting profession in Libya. Few significant results were also found for gender, but where they were found, males showed more ethical characteristics than females. This unusual result reinforces the dangers of gender stereotyping in business. Personal moral philosophy and moral intensity dimensions were generally found to be significant predictors of the three stages of ethical decision making studied. One implication of this is to give more attention to ethics in accounting education, making the connections between accounting practice and (in Libya) Islam. Overall, this study not only adds to the available empirical evidence on factors affecting ethical decision making, notably examining three stages of Restβs model, but also offers rare insights into the ethical views of practising management accountants and provides a benchmark for future studies of ethical decision making in Muslim majority countries and other parts of the developing world
Skin to calyx distance is not a predictive factor for miniaturized percutaneous nephrolithotomy outcomes
Traces of past activity in the Galactic Centre
The Milky Way centre hosts a supermassive Black Hole (BH) with a mass of
~4*10^6 M_Sun. Sgr A*, its electromagnetic counterpart, currently appears as an
extremely weak source with a luminosity L~10^-9 L_Edd. The lowest known
Eddington ratio BH. However, it was not always so; traces of "glorious" active
periods can be found in the surrounding medium. We review here our current view
of the X-ray emission from the Galactic Center (GC) and its environment, and
the expected signatures (e.g. X-ray reflection) of a past flare. We discuss the
history of Sgr A*'s past activity and its impact on the surrounding medium. The
structure of the Central Molecular Zone (CMZ) has not changed significantly
since the last active phase of Sgr A*. This relic torus provides us with the
opportunity to image the structure of an AGN torus in exquisite detail.Comment: Invited refereed review. Chapter of the book: "Cosmic ray induced
phenomenology in star forming environments" (eds. Olaf Reimer and Diego F.
Torres
Defending the genome from the enemy within:mechanisms of retrotransposon suppression in the mouse germline
The viability of any species requires that the genome is kept stable as it is transmitted from generation to generation by the germ cells. One of the challenges to transgenerational genome stability is the potential mutagenic activity of transposable genetic elements, particularly retrotransposons. There are many different types of retrotransposon in mammalian genomes, and these target different points in germline development to amplify and integrate into new genomic locations. Germ cells, and their pluripotent developmental precursors, have evolved a variety of genome defence mechanisms that suppress retrotransposon activity and maintain genome stability across the generations. Here, we review recent advances in understanding how retrotransposon activity is suppressed in the mammalian germline, how genes involved in germline genome defence mechanisms are regulated, and the consequences of mutating these genome defence genes for the developing germline
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