Prediction of forces and moments for hypersonic flight vehicle control effectors

This research project includes three distinct phases. For completeness, all three phases of the work are briefly described in this report. The goal was to develop methods of predicting flight control forces and moments for hypersonic vehicles which could be used in a preliminary design environment. The first phase included a preliminary assessment of subsonic/supersonic panel methods and hypersonic local flow inclination methods for such predictions. While these findings clearly indicated the usefulness of such methods for conceptual design activities, deficiencies exist in some areas. Thus, a second phase of research was conducted in which a better understanding was sought for the reasons behind the successes and failures of the methods considered, particularly for the cases at hypersonic Mach numbers. This second phase involved using computational fluid dynamics methods to examine the flow fields in detail. Through these detailed predictions, the deficiencies in the simple surface inclination methods were determined. In the third phase of this work, an improvement to the surface inclination methods was developed. This used a novel method for including viscous effects by modifying the geometry to include the viscous/shock layer

Measuring gravitational lens time delays using low-resolution radio monitoring observations

Obtaining lensing time delay measurements requires long-term monitoring campaigns with a high enough resolution (< 1 arcsec) to separate the multiple images. In the radio, a limited number of high-resolution interferometer arrays make these observations difficult to schedule. To overcome this problem, we propose a technique for measuring gravitational time delays which relies on monitoring the total flux density with low-resolution but high-sensitivity radio telescopes to follow the variation of the brighter image. This is then used to trigger high-resolution observations in optimal numbers which then reveal the variation in the fainter image. We present simulations to assess the efficiency of this method together with a pilot project observing radio lens systems with the Westerbork Synthesis Radio Telescope (WSRT) to trigger Very Large Array (VLA) observations. This new method is promising for measuring time delays because it uses relatively small amounts of time on high-resolution telescopes. This will be important because instruments that have high sensitivity but limited resolution, together with an optimum usage of followup high-resolution observations from appropriate radio telescopes may in the future be useful for gravitational lensing time delay measurements by means of this new method.Comment: 10 pages, 7 figures, accepted by MNRA

Functional analysis of a putative membrane-bound endo-β-1,4-glucanase from Panicum virgatum

Cellulose is the most abundant carbohydrate in the world and is degraded by the synergistic action of multiple enzymes. One large family of enzymes capable of hydrolyzing cellulose is glycoside hydrolase family 9 (GH9), which includes several endoglucanases. Recent research into the molecular biology of plants has revealed certain genes coding for endo-β-1,4-glucanases (EGases). The EGases in plants are primarily functional during cell elongation through wall stress relaxation. GH9 enzymes have been found in insects, bacteria, oomycetes, and fungi. In insects, EGases enable the organism to digest cellulose; in fungi, EGases are suspected to play an important role in obtaining nutrition for the fungi and may be associated with defense mechanisms. In these systems, EGases play an important role in breaking the internal bonds of cellulose resulting in a disruption of the crystalline structure. EGases are able to cleave cellulose at the β-1,4 linkages in the cellulose chain with a net inversion of anomeric configuration. A putative EGase from switchgrass (Panicum virgatum) was isolated from leaf cDNA. This gene of interest was cloned into Escherichia coli via the pET160 expression system. Selection by antibiotic resistance confirmed transformation of E. coli. Protein expression was detected via SDS-PAGE and tested to confirm cellulose lysing. The optimal pH and temperature were determined using 3,5-Dinitrosalycilic acid (DNSA) assay at different pH and temperature settings measuring reduced sugars released. Functionality in plants was determined through a gene rescue experiment using Arabidopsis thaliana mutants known to be deficient in putative EGase homologs. Switchgrass containing an overexpression of the EGase was compared to wildtype switchgrass via histology and microscopy. The confirmation of a functional EGase from switchgrass may aid in the development of switchgrass transformants with an amorphous cellulose structure, thereby reducing the amount of resources required during biofuel refinery

Impact of food, alcohol and pH on modified-release hydrocortisone developed to treat congenital adrenal hyperplasia.

BACKGROUND: We developed a modified-release hydrocortisone, Chronocort®, to replace the cortisol rhythm in patients with congenital adrenal hyperplasia. Food, alcohol and pH affect drug absorption and it is important to assess their impact when replicating a physiological rhythm. SUBJECTS AND METHODS: In vitro dissolution to study impact of alcohol and pH on Chronocort®. A Phase 1, three-period, cross over study in 18 volunteers to assess the impact of food on Chronocort® and to compare bioavailability to immediate-release hydrocortisone. RESULTS: In vitro dissolution of Chronocort® was not affected by gastrointestinal pH up to 6.0 nor by an alcohol content up to 20 % v/v. Food delayed and reduced the rate of absorption of Chronocort® as reflected by a longer Tmax (fed vs fasted: 6.75 hrs vs 4.5 hrs, p=0005) and lower Cmax (549.49 vs 708.46, nmol/L, ratio 77% with CI 71 - 85). Cortisol exposure was similar in fed and fasted state: Geo LSmean ratio (CI) AUC0 t for fed/fasted was 108.33% (102.30 - 114.72%). Cortisol exposure was higher for Chronocort® compared to immediate-release hydrocortisone: Geo LSmean ratios (CI) 118.83% (111.58 - 126.54%); however, derived free cortisol showed cortisol exposure CIs were within 80.0 125.0 %: Geo LSmean ratio (CI) for AUC0 t 112.73% (105.33 - 120.65%). CONCLUSIONS: Gastric pH ≤ 6.0 and alcohol do not effect hydrocortisone release from Chronocort®. Food delays Chronocort® absorption but cortisol exposure is similar in the fasted and fed state and exposure as assessed by free cortisol is similar between Chronocort® and immediate-release hydrocortisone

The growth of galaxies in cosmological simulations of structure formation

We use hydrodynamic simulations to examine how the baryonic components of galaxies are assembled, focusing on the relative importance of mergers and smooth accretion in the formation of ~L_* systems. In our primary simulation, which models a (50\hmpc)^3 comoving volume of a Lambda-dominated cold dark matter universe, the space density of objects at our (64-particle) baryon mass resolution threshold, M_c=5.4e10 M_sun, corresponds to that of observed galaxies with L~L_*/4. Galaxies above this threshold gain most of their mass by accretion rather than by mergers. At the redshift of peak mass growth, z~2, accretion dominates over merging by about 4:1. The mean accretion rate per galaxy declines from ~40 M_sun/yr at z=2 to ~10 M_sun/yr at z=0, while the merging rate peaks later (z~1) and declines more slowly, so by z=0 the ratio is about 2:1. We cannot distinguish truly smooth accretion from merging with objects below our mass resolution threshold, but extrapolating our measured mass spectrum of merging objects, dP/dM ~ M^a with a ~ -1, implies that sub-resolution mergers would add relatively little mass. The global star formation history in these simulations tracks the mass accretion rate rather than the merger rate. At low redshift, destruction of galaxies by mergers is approximately balanced by the growth of new systems, so the comoving space density of resolved galaxies stays nearly constant despite significant mass evolution at the galaxy-by-galaxy level. The predicted merger rate at z<~1 agrees with recent estimates from close pairs in the CFRS and CNOC2 redshift surveys.Comment: Submitted to ApJ, 35 pp including 15 fig

Vegetable plants for home and commercial growers

Cover title

Two-Dimensional Hydrodynamic Simulations of Convection in Radiation-Dominated Accretion Disks

The standard equilibrium for radiation-dominated accretion disks has long been known to be viscously, thermally, and convectively unstable, but the nonlinear development of these instabilities---hence the actual state of such disks---has not yet been identified. By performing local two-dimensional hydrodynamic simulations of disks, we demonstrate that convective motions can release heat sufficiently rapidly as to substantially alter the vertical structure of the disk. If the dissipation rate within a vertical column is proportional to its mass, the disk settles into a new configuration thinner by a factor of two than the standard radiation-supported equilibrium. If, on the other hand, the vertically-integrated dissipation rate is proportional to the vertically-integrated total pressure, the disk is subject to the well-known thermal instability. Convection, however, biases the development of this instability toward collapse. The end result of such a collapse is a gas pressure-dominated equilibrium at the original column density.Comment: 10 pages, 7 figures, accepted for publication in ApJ. Please send comments to [email protected]

Little Inflatons and Gauge Inflation

Cosmological inflation gives a natural answer for a variety of cosmological questions, including the horizon problem, the flatness problem, and others. However, inflation yields new questions relating to the flatness of the inflaton potential. Recent studies of ``little'' fields, a special class of pseudo-Goldstone bosons, have shown it is possible to protect the mass of a field while still yielding order one interactions with other fields. In this paper, we will show that ``little inflatons'' are natural candidates for the slow roll field of hybrid inflation models. We consider both supersymmetric and non-supersymmetric models, and give a simple examples based on approximate Abelian symmetries which solve the inflaton flatness problem of supergravity. We also present hybrid models in which components of gauge fields in higher dimensions play the role of the inflaton. Protected by higher-dimensional gauge symmetry, they, too, naturally have large couplings while suppressed mass terms. We summarize the implications of the new WMAP data on such models.Comment: 25 pages; corrections, references added, discussion modified including consideration of WMAP result

From Galaxy-Galaxy Lensing to Cosmological Parameters

Galaxy-galaxy lensing measures the mean excess surface density DS(r) around a sample of lensing galaxies. We develop a method for combining DS(r) with the galaxy correlation function xi_gg(r) to constrain Omega_m and sigma_8, going beyond the linear bias model to reach the level of accuracy demanded by current and future measurements. We adopt the halo occupation distribution (HOD) framework, and we test its applicability to this problem by examining the effects of replacing satellite galaxies in the halos of an SPH simulation with randomly selected dark matter particles from the same halos. The difference between dark matter and satellite galaxy radial profiles has a ~10% effect on DS(r) at r<1 Mpc/h. However, if radial profiles are matched, the remaining impact of individual subhalos around satellite galaxies and environmental dependence of the HOD at fixed halo mass is <5% in DS(r) for 0.1<r<15 Mpc/h. We develop an analytic approximation for DS(r) that incorporates halo exclusion and scale-dependent halo bias, and we demonstrate its accuracy with tests against a suite of populated N-body simulations. We use the analytic model to investigate the dependence of DS(r) and the galaxy-matter correlation function xi_gm(r) on Omega_m and sigma_8, once HOD parameters for a given cosmological model are pinned down by matching xi_gg(r). The linear bias prediction is accurate for r>2 Mpc/h, but it fails at the 30-50% level on smaller scales. The scaling of DS(r) ~ Omega_m^a(r) sigma_8^b(r) approaches the linear bias expectation a=b=1 at r>10 Mpc/h, but a(r) and b(r) vary from 0.8 to 1.6 at smaller r. We calculate a fiducial DS(r) and scaling indices a(r) and b(r) for two SDSS galaxy samples; galaxy-galaxy lensing measurements for these samples can be combined with our predictions to constrain Omega_m and sigma_8.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical Journa