Simulation in an interactive computer environment

PhD ThesisThis thesis is a report of an investigation into the possible advantages to be gained by running computer simulations interactively. Models relevant to administrative, teaching and research work were constructed for the study, and the merits of the interactive use of deterministic models, stochastic equations and Monte-Carlo simulations were examined. In order to be able to draw worthwhile conclusions from the investigation it was necessary to study sustantial systems which had proved to require computer simulation for their elucidation. The first model described is a deterministic portrayal of the use of university lecture rooms which was written as an aid towards evaluating the need for additional rooms in an expanding university. The part played by interaction is to make easier the incorpration of human experience into the planning mechanism. Population genetics provided the next system, and it is shown how a model using a set of stochastic equations in conjunction with fast graphical output may be of value in teaching. A Monte-Carlo approach is demonstrated to be unsuitable for interactive use. The final simulation also employs stochastic equations, designed to represent a system from the field of cell cycle kinetics whose action is not fully understood. Using the model interactively allows the researcher to form an appreciation of the consequences of altering its parameters and to fit experimental data with more perception than is possible using purely algorithmic methods. Introductions are given to the two biological systems dealt with, so that the results of using the models can be discussed in relation to the genetics and cytokinetics Lnvo lved as well as purely in the context of the interactive use of simulmtion.Science Research Council

Differential Metabolite Profiles during Fruit Development in High-Yielding Oil Palm Mesocarp

10.1371/journal.pone.0061344PLoS ONE84

Midlife body mass index, central adiposity and neuropsychological performance over 10 years in women living with and without HIV

Background and objective: Observations of overweight and obesity in association with neuropsychological performance (NP) vary over the adult life course depending on baseline levels, biological sex, age, race, temporality of measurements, and other factors. Therefore, similar published analyses across cohorts are inconsistent. In our sample of women living with HIV (WLWH) and women without HIV (WWOH), we conducted comparable analyses as those published in men with and without HIV. We examined cross-sectional and longitudinal associations between body mass index (BMI) and waist circumference (WC) and NP. Methods: Four hundred thirty two 432 virologically-suppressed WLWH and 367 WWOH, ≥40 years in the Women’s Interagency HIV Study (WIHS) with anthropometry and NP assessments every two years from 2009-2019 were included in the study. Demographically-adjusted T-scores were calculated for six NP domains: learning, memory, executive function, processing speed, attention and working memory, and motor function. Multivariable linear regression models stratified by HIV status were used to examine cross-sectional associations of BMI and WC by NP domain; repeated measures analyses assessed baseline BMI and WC in association with longitudinal change in NP. Covariates included sociodemographic, behavioral, and HIV-related characteristics. Results: At baseline among all women, the median age was 45 years, 65% were Non-Latinx Black women, and 45% were obese women. Obese WLWH (BMI≥30.0 kg/m2) had poorer executive function (β=-2.27, 95%CI [-4.46, -0.07]) versus WLWH with healthy BMI (18.5–24.9 kg/m2). Longitudinally over ~8 years, obese versus overweight WWOH improved on memory (β=2.19, 95%CI [0.13, 4.26]), however overweight versus healthy WWOH experienced declining memory (β= -2.67, 95%CI [-5.40, -0.07]). Increasing WC was associated with declining executive, processing speed, and motor function (p’s<0.05); an at-risk WC was associated with improved memory (β=1.81, 95%CI [0.19, 3.44]) among WWOH. Among WLWH, increasing BMI was associated with improved learning (β=0.07, 95%CI [0.00, 0.15]. Conclusion: Our cross-sectional and longitudinal analyses evaluating the associations of BMI and WC and NP were mixed compared to previous reports. This illustrates the importance of sociodemographic characteristics, baseline levels of exposures and outcomes, HIV status, temporality of measurements, and other factors when evaluating aging HIV epidemiology study results

GOALS-JWST: Mid-infrared Spectroscopy of the Nucleus of NGC 7469

We present mid-infrared spectroscopic observations of the nucleus of the nearby Seyfert galaxy NGC 7469 taken with the MIRI instrument on the James Webb Space Telescope (JWST) as part of Directors Discretionary Time Early Release Science program 1328. The high-resolution nuclear spectrum contains 19 emission lines covering a wide range of ionization. The high-ionization lines show broad, blueshifted emission reaching velocities up to 1700 km s−1 and FWHM ranging from ∼500 to 1100 km s−1. The width of the broad emission and the broad-to-narrow line flux ratios correlate with ionization potential. The results suggest a decelerating, stratified, AGN-driven outflow emerging from the nucleus. The estimated mass outflow rate is 1–2 orders of magnitude larger than the current black hole accretion rate needed to power the AGN. Eight pure rotational H2 emission lines are detected with intrinsic widths ranging from FWHM ∼125 to 330 km s−1. We estimate a total mass of warm H2 gas of ∼1.2 × 107M⊙ in the central 100 pc. The PAH features are extremely weak in the nuclear spectrum, but a 6.2 μm PAH feature with an equivalent width of ∼0.07 μm and a flux of 2.7 × 10−17 W m−2 is detected. The spectrum is steeply rising in the mid-infrared, with a silicate strength of ∼0.02, significantly smaller than seen in most PG QSOs but comparable to other Seyfert 1s. These early MIRI mid-infrared IFU data highlight the power of JWST to probe the multiphase interstellar media surrounding actively accreting supermassive black holes

GOALS-JWST: Pulling Back the Curtain on the AGN and Star Formation in VV 114

We present results from the James Webb Space Telescope Director's Discretionary Time Early Release Science program 1328 targeting the nearby, luminous infrared galaxy, VV 114. We use the MIRI and NIRSpec instruments to obtain integral-field spectroscopy of the heavily obscured eastern nucleus (V114E) and surrounding regions. The spatially resolved, high-resolution spectra reveal the physical conditions in the gas and dust over a projected area of 2–3 kpc that includes the two brightest IR sources, the NE and SW cores. Our observations show for the first time spectroscopic evidence that the SW core hosts an active galactic nucleus as evidenced by its very low 6.2 μm and 3.3 μm polycyclic aromatic hydrocarbon equivalent widths (0.12 and 0.017 μm, respectively) and mid- and near-IR colors. Our observations of the NE core show signs of deeply embedded star formation including absorption features due to aliphatic hydrocarbons, large quantities of amorphous silicates, as well as HCN due to cool gas along the line of sight. We detect elevated [Fe ii]/Pfα consistent with extended shocks coincident with enhanced emission from warm H2, far from the IR-bright cores and clumps. We also identify broadening and multiple kinematic components in both H2 and fine structure lines caused by outflows and previously identified tidal features

GOALS-JWST: Small Neutral Grains and Enhanced 3.3 μm PAH Emission in the Seyfert Galaxy NGC 7469

We present James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) integral field spectroscopy of the nearby luminous infrared galaxy NGC 7469. We take advantage of the high spatial/spectral resolution and wavelength coverage of JWST/NIRSpec to study the 3.3 μm neutral polycyclic aromatic hydrocarbon (PAH) grain emission on ∼200 pc scales. A clear change in the average grain properties between the star-forming ring and the central AGN is found. Regions in the vicinity of the AGN, with [Ne iii]/[Ne ii] > 0.25, tend to have larger grain sizes and lower aliphatic-to-aromatic (3.4/3.3) ratios, indicating that smaller grains are preferentially removed by photodestruction in the vicinity of the AGN. PAH emission at the nucleus is weak and shows a low 11.3/3.3 PAH ratio. We find an overall suppression of the total PAH emission relative to the ionized gas in the central 1 kpc region of the AGN in NGC 7469 compared to what has been observed with Spitzer on 3 kpc scales. However, the fractional 3.3 μm–to–total PAH power is enhanced in the starburst ring, possibly due to a variety of physical effects on subkiloparsec scales, including recurrent fluorescence of small grains or multiple photon absorption by large grains. Finally, the IFU data show that while the 3.3 μm PAH-derived star formation rate (SFR) in the ring is 27% higher than that inferred from the [Ne ii] and [Ne iii] emission lines, the integrated SFR derived from the 3.3 μm feature would be underestimated by a factor of 2 due to the deficit of PAHs around the AGN, as might occur if a composite system like NGC 7469 were to be observed at high redshift

GOALS-JWST: tracing AGN feedback on the star-forming interstellar medium in NGC 7469

Galaxie

GOALS-JWST: resolving the circumnuclear gas dynamics in NGC 7469 in the mid-infrared

Galaxie