499 research outputs found
Creating native registry functions to accommodate mutant libraries
The current registry system accommodates normal parts fairly well but has difficulty when adding mutant libraries. If all mutant offspring were added as new parts, the registry would be comprehensive but the parts registry would become filled with parts and eventually become unmanageable to navigate. If the mutants were added directly to the source’s page, it could become unwieldy and unintuitive to find. We propose a system of adding a few features to the registry that SHALL allow a user-friendly method of visualizing mutant offspring and siblings while condensing the registry as much as possible when mutants are introduced to allow for easier navigation
Effects of Gypsy Moth Outbreaks on North American Woodpeckers
We examined the effects of the introduced gypsy moth (Lymantria dispar) on seven species of North American woodpeckers by matching spatially explicit data on gypsy moth outbreaks with data on breeding and wintering populations. In general, we detected modest effects during outbreaks: during the breeding season one species, the Red-headed Woodpecker (Melanerpes erythrocephalus), increased over pre-outbreak levels, while during the winter one species, the Yellow-bellied Sapsucker (Sphyrapicus varius), increased and one, the Downy Woodpecker (Picoides pubescens), decreased from pre-outbreak levels. Responses following outbreaks were similarly variable, and in general we were unsuccessful at predicting population responses to outbreaks from a priori knowledge of woodpecker ecology and behavior. We did, however, find evidence that the response of at least half of the species changed over the 34-year period covered by the study: except for the Northern Flicker (Colaptes auratus), whose response to outbreaks during the winter decreased, populations generally responded more positively to outbreaks with time. This temporal response suggests that North American woodpeckers may be taking greater advantage of the resource pulse and/or habitat changes caused by outbreaks of this exotic pest now than previously, so in the future the effects of gypsy moth outbreaks on these species may increase
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Development of a Framework for Analyzing the Effects of a Micro Pin Fin Array on the Catalytic Combustion of Hydrogen in Micro-channels
An experimental framework for investigation of the effects of Micro Pin Fin Arrays (MPFA) on the fuel oxidation efficiency of catalytic combustion is presented in this thesis. Complete combustion of the fuel is essential for operation at maximum efficiency and high standards of environmental cleanliness desired in existing microscale combustion applications. Higher residence times can increase the conversion rate of fuel as there is more time for the reaction to occur. Flow around a staggered array of pin fins causes increased residence times over a plain rectangular microgap due to the impingement of the flow on pins and the slower wake region behind the pins. The framework consists of detailed infrared thermography of the MPFA to characterize the surface temperature, scanning electron microscopy to characterize the catalyst morphology, and Energy Dispersive X-ray Spectroscopy (EDAX) to characterize the elemental composition of the catalyst surface. In addition to the local measurements, gas chromatography was used to identify the composition of the exhaust gas. To test the framework, a preliminary experiment of two different pin fin array geometries were investigated at various combustion temperatures and residence times. Based on the results of the experiment, further refinement of the framework is proposed
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Stability and Liftoff of Non-premixed Large Hydrocarbon Flames in MILD Conditions
The Moderate or Intense Low-oxygen Dilution (MILD) combustion regime has received interest from the industrial furnace and gas turbine engine industries due to attractive properties of reduced NO[subscript x] emissions and high thermal efficiency. MILD combustion is characterized by low oxygen concentrations (i.e. 3%-9% by volume) and high reactant temperatures. A fundamental understanding of the physics governing MILD combustion is required to design effective practical combustion devices. While the physics relevant to MILD combustion of small hydrocarbon fuels such as methane and ethylene have been well-characterized, the behavior of large hydrocarbon fuels, such as Jet-A, have not. This is significant because many practical devices such as internal combustion engines and gas turbine engines are designed to operate using large hydrocarbon fuels. With this background and motivation, the focus of the current study was to understand the mechanisms governing stability and ignition of these flames in the MILD regime.
To this end, a series of experimental and numerical studies were conducted to identify the physics governing lifted large hydrocarbon flames in the MILD regime. A jet in hot coflow (JHC) burner was used to stabilize a large hydrocarbon flame in a laboratory environment. The coflow used a premixed CHâ‚„/Hâ‚‚ secondary burner to provide an oxidizer stream at high temperature and with low oxygen concentration, which emulates MILD conditions. The coflow temperature was varied between 1300K and 1500K and the oxygen concentration was varied between 3% and 9% by volume. Three different large hydrocarbon fuels (i.e. Jet-A and two experimental fuels) were vaporized and issued into the hot coflow, with Reynolds numbers based on the inner jet diameter ranging from 3,750 to 10,000. The fuel jet exit temperature was varied from 525K to 625K. The liftoff heights of the resulting flames were measured using OH* chemiluminescence, as the flames were not always visible. Opposed flow laminar diffusion flames simulations were employed to determine how the interaction between chemistry and strain may affect flame stability. Ignition delay calculations were used to determine how ignition chemistry may affect flame liftoff without considering the effect of mixing.
Several conclusions were made from the measurements and simulations. Oscillation of the instantaneous flame liftoff height was observed and was attributed to the cyclic advection of burned fluid downstream and the subsequent autoignition of unburned fluid. An increase in the fuel jet temperature was found to stabilize the flames closer to the jet exit, which was attributed to an increase in entrainment caused by higher fuel jet velocities. Flames in a coflow with 3% Oâ‚‚ at an exit temperature of 1300K were found to exhibit a decrease in liftoff height with increasing fuel jet Reynolds number. This counter-intuitive trend was not observed in flames burning in a coflow with higher temperatures or in coflows with higher Oâ‚‚ concentrations. The decrease in flame liftoff height with Reynolds number was attributed to the transport of formaldehyde into unburned mixture via the observed oscillations in the flame base. This conclusion was supported by both PLIF measurements performed by previous researchers on gaseous MILD flames and by numerical calculations. Opposed flame simulations indicated that formaldehyde production was increased with strain rate, which is analogous to an increase in the fuel jet velocity. Ignition delay calculations indicated that formaldehyde addition decreased ignition delay times, which results in lower flame liftoff heights. Opposed flow flame simulations indicated that the effect of changes in CHâ‚‚O production was diminished at increased coflow oxygen levels (i.e. 6% and 9%) and elevated coflow temperatures (i.e. 1400K and 1500K) due to lower formaldehyde production
Local Avian Density Influences Risk of Mortality from Window Strikes
Up to a billion birds die per year in North America as a result of striking windows. Both transparent and reflective glass panes are a cause for concern, misleading birds by either acting as invisible, impenetrable barriers to desired resources, or reflecting those resources over a large surface area. A high number of window strikes occur during migration, but little is known about the factors of susceptibility, or whether particular avian taxa are more vulnerable than others. We report on a study of window strikes and mist-netting data at the Virginia Zoological Park (Norfolk, Virginia, USA), conducted in the autumn of 2013 and 2014. We focused on three factors likely to contribute to an individual\u27s predisposition to collide with windows: (i) taxonomic classification, (ii) age, and (iii) migrant vs. resident status. Thrushes, dominated by the partial migrant American Robin (Turdus migratorius), were significantly less likely to strike glass than be sampled in mist nets (χ2 = 9.21, p = 0.002), while wood-warblers (Parulidae) were more likely to strike than expected (χ2 = 13.55, p \u3c 0.001). The proportion of juveniles striking windows (45.4%) was not significantly different (χ2 = 0.05, p = 0.827) than the population of juvenile birds naturally occurring at the zoo (48.8%). Migrants, however, were significantly more susceptible to window strikes than residents (χ2 = 6.35, p = 0.012). Our results suggest that resident birds are able to learn to avoid and thus reduce their likelihood of striking windows; this intrinsic risk factor may help explain the apparent susceptibility of certain taxa to window strikes
A porcine model system of BRCA1 driven breast cancer
BRCA1 is a breast and ovarian tumor suppressor. Hereditary mutations in BRCA1 result in a predisposition to breast cancer, and BRCA1 expression is down-regulated in ~30% of sporadic cases. The function of BRCA1 remains poorly understood, but it appears to play an important role in DNA repair and the maintenance of genetic stability. Mouse models of BRCA1 deficiency have been developed in an attempt to understand the role of the gene in vivo. However, the subtle nature of BRCA1 function and the well-known discrepancies between human and murine breast cancer biology and genetics may limit the utility of mouse systems in defining the function of BRCA1 in cancer and validating the development of novel therapeutics for breast cancer. In contrast to mice, pig biological systems and cancer genetics appear to more closely resemble their human counterparts. To determine if BRCA1 inactivation in pig cells promotes their transformation and may serve as a model for the human disease, we developed an immortalized porcine breast cell line and stably inactivated BRCA1 using miRNA. The cell line developed characteristics of breast cancer stem cells and exhibited a transformed phenotype. These results validate the concept of using pigs as a model to study BRCA1 defects in breast cancer and establish the first porcine breast tumor cell line
(±)-2-exo- and endo-Methylamino-1,2,3,4-tetrahydro-1,4-ethanonapthalene Hydrochloride
This is the published version
A Genetic Porcine Model of Cancer
The large size of the pig and its similarity in anatomy, physiology, metabolism, and genetics to humans make it an ideal platform to develop a genetically defined, large animal model of cancer. To this end, we created a transgenic oncopig line encoding Cre recombinase inducible porcine transgenes encoding KRASG12D and TP53R167H, which represent a commonly mutated oncogene and tumor suppressor in human cancers, respectively. Treatment of cells derived from these oncopigs with the adenovirus encoding Cre (AdCre) led to KRASG12D and TP53R167H expression, which rendered the cells transformed in culture and tumorigenic when engrafted into immunocompromised mice. Finally, injection of AdCre directly into these oncopigs led to the rapid and reproducible tumor development of mesenchymal origin. Transgenic animals receiving AdGFP (green fluorescent protein) did not have any tumor mass formation or altered histopathology. This oncopig line could thus serve as a genetically malleable model for potentially a wide spectrum of cancers, while controlling for temporal or spatial genesis, which should prove invaluable to studies previously hampered by the lack of a large animal model of cancer
Zanamivir susceptibility monitoring and characterization of influenza virus clinical isolates obtained during phase II clinical efficacy studies
Zanamivir is a highly selective neuraminidase (NA) inhibitor with
demonstrated clinical efficacy against influenza A and B virus infections.
In phase II clinical efficacy trials (NAIB2005 and NAIB2008), virological
substudies showed mean reductions in virus shedding after 24 h of
treatment of 1.5 to 2.0 log(10) 50% tissue culture infective doses
compared to a placebo, with no reemergence of virus after the completion
of therapy. Paired isolates (n = 41) obtained before and during therapy
with zanamivir demonstrated no shifts in susceptibility to zanamivir when
measured by NA assays, although for a few isolates NA activity was too low
to evaluate. In plaque reduction assays in MDCK cells, the susceptibility
of isolates to zanamivir was extremely variable even at baseline and did
not correlate with the speed of resolution of virus shedding. Isolates
with apparent limited susceptibility to zanamivir by plaque reduction
proved highly susceptible in vivo in the ferret model. Further sequence
analysis of paired isolates revealed no changes in the hemagglutinin and
NA genes in the majority of isolates. The few changes observed were all
natural variants. No amino acid changes that had previously been
identified in vitro as being involved with reduced susceptibility to
zanamivir were observed. These studies highlighted problems associated
with monitoring susceptibility to NA inhibitors in the clinic, in that no
reliable cell-based assay is available. At present the NA assay is the
best available predictor of susceptibility to NA inhibitors in vivo, as
measured in the validated ferret model of infection
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