Numerical Aerodynamic Simulation (NAS)

The history of the Numerical Aerodynamic Simulation Program, which is designed to provide a leading-edge capability to computational aerodynamicists, is traced back to its origin in 1975. Factors motivating its development and examples of solutions to successively refined forms of the governing equations are presented. The NAS Processing System Network and each of its eight subsystems are described in terms of function and initial performance goals. A proposed usage allocation policy is discussed and some initial problems being readied for solution on the NAS system are identified

Massive pre-main sequence stars in M17

The formation process of massive stars is still poorly understood. Massive young stellar objects (mYSOs) are deeply embedded in their parental clouds, they are rare and thus typically distant, and their reddened spectra usually preclude the determination of their photospheric parameters. M17 is one of the best studied HII regions in the sky, is relatively nearby, and hosts a young stellar population. With X-shooter on the ESO Very Large Telescope we have obtained optical to near-infrared spectra of candidate mYSOs, identified by Hanson et al. (1997), and a few OB stars in this region. The large wavelength coverage enables a detailed spectroscopic analysis of their photospheres and circumstellar disks. We confirm the pre-main sequence (PMS) nature of six of the stars and characterise the O stars. The PMS stars have radii consistent with being contracting towards the main sequence and are surrounded by a remnant accretion disk. The observed infrared excess and the (double-peaked) emission lines provide the opportunity to measure structured velocity profiles in the disks. We compare the observed properties of this unique sample of young massive stars with evolutionary tracks of massive protostars by Hosokawa & Omukai (2009), and propose that these mYSOs near the western edge of the HII region are on their way to become main-sequence stars ($\sim 6 - 20$ $M_{\odot}$) after having undergone high mass-accretion rates (${\dot{M}_{\rm acc}} \sim 10^{-4} - 10^{-3}$ $M_{\odot}$ $\rm yr^{-1}$). Their spin distribution upon arrival at the zero age main sequence (ZAMS) is consistent with that observed for young B stars, assuming conservation of angular momentum and homologous contraction.Comment: Accepted for publication in A&A. Appendixes A and B have been truncated due to size limitations, the full version will be available on A&

Spectral absorption coefficients of carbon, nitrogen, and oxygen atoms

Spectral absorption coefficients of carbon, nitrogen, and oxygen atoms tabulated for use in radiant energy transfer calculation

Spectroscopic variability of massive pre-main-sequence stars in M17

It is a challenge to study the formation process of massive stars: their formation time is short, they are few, often deeply embedded, and at relatively large distances. Our strategy is to study the outcome of the star formation process and to look for signatures remnant of the formation. We have access to a unique sample of (massive) pre-main-sequence (PMS) stars in the giant HII region M17, showing a photosphere and circumstellar disk. The aim is to determine the variability properties of the hot gaseous disks to understand the physical origin of the emission lines and identify dominant physical processes in these disks. We have obtained multiple-epoch (4-5 epochs) VLT/X-shooter spectra of six young stars in M17 covering about a decade. Using stacked spectra we update the spectral classification and identify circumstellar features. With the temporal variance method (TVS) we determine the extent and amplitude of the spectral line variations. The double-peaked emission lines in the PMS stars with gaseous disks are used to determine peak-to-peak velocities, V/R-ratios and the radial velocity of the systems. We identify many disk features, under which a new detection of CO bandhead and CI emission. In three of the stars we detect spectral variability, mainly in lines originating in the circumstellar disk, in a velocity range up to 320 km/s. In two PMS stars the ratio between the blue and red peaks shows a correlation with the peak-to-peak velocity, possibly explained by a spiral-arm structure in the disk. The PMS stars with variability are at similar positions in the HRD but show significant differences in disk lines and variability. The extent and timescale of the variability differs for each star and per line (sets). We find indications for an accretion flow, slow disk winds and/or disk structures in the hot gaseous inner disk as the cause of the variability in these PMS stars.Comment: 27 pages, 24 figures, accepted for publication in Astronomy and Astrophysics, abstract abbreviate

Tables of joint probabilities useful in evaluating mixed acceptance sampling plans

Tables of joint probabilities useful in evaluating mixed acceptance sampling plan

Immobilised growth factors for scalable cell therapy manufacturing platforms

Regenerative medicine has the potential to establish or restore normal function in defective tissues and organs. The realisation of such therapies is restricted due to costs, lack of scalability and inefficient manufacturing process controls. A major contributor to cost is the use of expensive growth factors supplemented into media at high concentrations. In vivo, growth factors exist in soluble, immobilised and transmembrane forms, expressed in a spatiotemporal fashion within the stem cell niche. In comparison to soluble equivalents, immobilised growth factors exhibit increased potency, distinct functional activities, improved cell phenotypic control and act in synergy with other soluble and immobilised ligands. To date, most research into immobilised growth factors has been restricted to planar cell culture surfaces such as tissue culture plastics which have limited scalability. To address the scalability limitations, a novel growth factor immobilisation technology was developed using magnetic microparticles which can be scaled with respect to surface area to volume ratio in standard stirred tank bioreactors. Three clinically relevant growth factors, SCF, TPO and GM-CSF were immobilised and were shown to remain functionally active where surface concentration could be manipulated in a number of ways. Through a series of experiments, it was demonstrated that immobilised growth factors exhibited ~10-fold increase in potency compared with soluble equivalents and remain stable for up to 192 hours following recycling during multiple media passages. Immobilised growth factors were able to expand more cells over a longer period of time after transient exposure and finally, the immobilisation technique was successfully applied to the expansion of umbilical cord derived haematopoietic stem cells using immobilised SCF. The immobilisation method described here has the potential to significantly reduce media costs in large scale cell manufacturing processes

Diffuse interstellar bands in the HII region M17: Insights into their relation with the total-to-selective visual extinction RVR_V

Diffuse interstellar bands (DIBs) are broad absorption features measured in sightlines probing the diffuse interstellar medium. Although large carbon-bearing molecules have been proposed as the carriers producing DIBs, their identity remains unknown. The sight line to the young massive star-forming region M17 shows anomalous extinction in the sense that the total-to-selective extinction parameter differs significantly from the average Galactic value and may reach values $R_{V} > 4$. Given the high $R_V$ values, we investigate whether the DIBs in sight lines towards young OB stars in M17 show a peculiar behaviour. We measure the properties of the most prominent DIBs in M17 and study these as a function of $E(B-V)$ and $R_{V}$. The DIB strengths in M17 concur with the observed relations between DIB equivalent width and reddening $E(B-V)$ in Galactic sight lines. For several DIBs we discover a linear relation between the normalised DIB strength EW/$A_{V}$ and $R_{V}^{-1}$. These trends suggest two groups: (i) a group of ten moderately strong DIBs that show a sensitivity to changes in $R_{V}$ that is modest and proportional to DIB strength, and (ii) a group of four very strong DIBs that react sensitively and to a similar degree to changes in $R_{V}$, but in a way that does not appear to depend on DIB strength. The DIB behaviour as a function of reddening is not peculiar in sight lines to M17. Also, we do not detect anomalous DIB profiles as seen in Her 36. DIBs are stronger, per unit visual extinction, in sight lines characterised by a smaller value of $R_{V}$ (large fraction of small dust particles). New relations between extinction normalised DIB strengths, EW/$A_V$, and $R_V$ support the idea that DIB carriers and interstellar dust are connected. Given the distinct behaviour of two groups of DIBs, different types of carriers do not necessarily relate to the dust grains in a similar way.Comment: Abstract has been shortened. Accepted for publication in A&A. 14 pages, 7 pages of appendix, 28 figure

Twelve: Race and gender representations in Hidalgo County petit jury selections, 1950–1960

The purpose of this thesis is to address the composition of Hidalgo County petit (small) juries from 1950-1960 on the basis of race and gender in which I will argue that the racial composition of the County’s petit juries was predominantly Anglo. Following the inclusion of women into juror selection pools after 1954, I assert that Anglo females were selected at higher rates than Mexican American males and females during the same time period which continued the political and civic marginalization of the county’s Mexican American population. This work addresses the social and political environment of Hidalgo County. Along with this discussion, my use of Hidalgo County’s Juror Time Books and selected criminal/civil court cases will make evident that socio-political and civic marginalization was present in Hidalgo County; thus, reflecting a distinct bias against Mexican American males and females during the 1950s