Application of control theory to dynamic systems simulation

The application of control theory is applied to dynamic systems simulation. Theory and methodology applicable to controlled ecological life support systems are considered. Spatial effects on system stability, design of control systems with uncertain parameters, and an interactive computing language (PARASOL-II) designed for dynamic system simulation, report quality graphics, data acquisition, and simple real time control are discussed

An approach to the preliminary evaluation of Closed Ecological Life Support System (CELSS) scenarios and control strategies

Life support systems for manned space missions are discussed. A scenario analysis method was proposed for the initial step of comparing possible partial or total recycle scenarios. The method is discussed in detail

Learning to serve together : creating an inter-continental classroom for service-learning

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Human Herpesvirus-8 Glycoprotein B Interacts with Epstein–Barr Virus (EBV) Glycoprotein 110 but Fails to Complement the Infectivity of EBV Mutants

AbstractTo characterize human herpesvirus 8 (HHV-8) gB, the open reading frame was PCR amplified from the HHV-8-infected cell line BCBL-1 and cloned into an expression vector. To facilitate detection of expressed HHV-8 gB, the cytoplasmic tail of the glycoprotein was tagged with the influenza hemagglutinin (HA) epitope. Expression of tagged HHV-8 gB (gB-HA), as well as the untagged form, was readily detected in CHO-K1 cells and several lymphoblastoid cell lines (LCLs). HHV-8 gB-HA was sensitive to endoglycosidase H treatment, and immunofluorescence revealed that HHV-8 gB-HA was detectable in the perinuclear region of CHO-K1 cells. These observations suggest that HHV-8 gB is not processed in the Golgi and localizes to the endoplasmic reticulum or nuclear membrane. Because both HHV-8 and EBV are γ-herpesviruses, the ability of HHV-8 gB to interact with and functionally complement EBV gp110 was examined. HHV-8 gB-HA and EBV gp110 co-immunoprecipitated, indicating formation of hetero-oligomers. However, HHV-8 gB-HA and HHV-8 gB failed to restore the infectivity of gp110-negative EBV mutants. These findings indicate that although HHV-8 gB and EBV gp110 have similar patterns of intracellular localization and can interact, there is not sufficient functional homology to allow efficient complementation

Donor variability in HIV binding to peripheral blood mononuclear cells

<p>Abstract</p> <p>Background</p> <p>HIV infection of cells varies greatly between individuals, with multiple steps in the replication cycle potentially contributing to the variability. Although entry and post-entry variability of HIV infection levels in cells has been demonstrated, variability in HIV binding has not been examined. In this study, we examined variability of HIV binding to peripheral blood mononuclear cells (PBMC) from different donors.</p> <p>Results</p> <p>HIV binding to PBMC varied up to 3.9-fold between individuals and was independent of CD4. Replication of HIV in donor PBMC required CD4 and paralleled virus binding trends of donor PBMC. To assess the stability of virus binding phenotypes over time, HIV was bound to donors with low- and high-binding phenotypes. The binding phenotypes were maintained when tested weekly over a 4-week period for 3 of 4 donors, while one high-binding donor decreased to lower binding on the 4th week. The low- and high-binding phenotypes were also preserved across different HIV strains. Experiments performed to determine if there was an association between HIV binding levels and specific cell subset levels within PBMC showed no correlation, suggesting that HIV binds to multiple cell subsets.</p> <p>Conclusion</p> <p>These results show that differences exist in HIV binding to donor PBMC. Our data also show that HIV binding to donor PBMC is CD4-independent and can change over time, suggesting that virus binding variability is due to differences in the expression of changeable cell-surface host factors. Taken together, this study highlights the impact of cell-surface factors in HIV binding to, and infection of, PBMC which likely represents an important step in HIV infection <it>in vivo</it>.</p

Modeling and Simulation Techniques Used in High Strain Rate Projectile Impact

A series of computational models and simulations were conducted for determining the dynamic responses of a solid metal projectile impacting a target under a prescribed high strain rate loading scenario in three-dimensional space. The focus of this study was placed on two different modeling techniques within finite element analysis available in the Abaqus software suite. The first analysis technique relied heavily on more traditional Lagrangian analysis methods utilizing a fixed mesh, while still taking advantage of the finite difference integration present under the explicit analysis approach. A symmetry reduced model using the Lagrangian coordinate system was also developed for comparison in physical and computational performance. The second analysis technique relied on a mixed model that still made use of some Lagrangian modeling, but included smoothed particle hydrodynamics techniques as well, which are mesh free. The inclusion of the smoothed particle hydrodynamics was intended to address some of the known issues in Lagrangian analysis under high displacement and deformation. A comparison of the models was first performed against experimental results as a validation of the models, then the models were compared against each other based on closeness to experimentation and computational performance

Lunar and Martian hardware commonality

A number of different hardware elements were examined for possible Moon/Mars program commonality. These include manned landers; cargo landers, a trans-Mars injection (TMI) stage, traverse vehicles, unmanned surface rovers, habitation modules, and power supplies. Preliminary analysis indicates that it is possible to build a common two-stage manned lander. A single-stage, reusable lander may be practical for the lunar cast, but much less so for the Martian case, and commonality may therefore exist only at the subsystem level. A modified orbit transfer vehicle was examined as a potential cargo lander. Potential cargoes to various destinations were calculated for a Shuttle external tank sized TMI stage. A nuclear powered, long range traverse vehicle was conceptually designed and commonality is considered feasible. Short range, unmanned rovers can be made common without great effort. A surface habitation module may be difficult to make common due to difficulties in landing certain shapes on the Martian surface with aerobraking landers. Common nuclear power sources appear feasible. High temperature radiators appear easy to make common. Low temperature radiators may be difficult to make common. In most of these cases, Martian requirements determine the design

What are women's mode of birth preferences and why? A systematic scoping review.

BACKGROUND:The optimal caesarean section rate is estimated to be between 10-15%; however, it is much higher in high and many middle-income countries and continues to be lower in some middle and low-income countries. While a range of factors influence caesarean section rates, women's mode of birth preferences also play a role. The aim of this study was to map the literature in relation to women's mode of birth preferences, and identify underlying reasons for, and factors associated with, these preferences. METHOD:Using a scoping review methodology, quantitative and qualitative evidence was systematically considered. To identify studies, PubMed, Maternity and Infant Care, MEDLINE, and Web of Science were searched for the period from 2008 to 2018, and reference lists of included studies were examined. FINDINGS:A total of 65 studies were included. While the majority of women prefer a vaginal birth, between 5-20% in high-income countries and 1.4 to 50% in low-middle-income countries prefer a caesarean section. The six main reasons or factors associated with a mode of birth preference were: (1) perceptions of safety; (2) fear of pain; (3) previous birth experience; (4) encouragement and dissuasion from health professionals; (5) social and cultural influences; and (6) access to information and educational levels. CONCLUSION:To help ensure women receive the required care that is aligned with their preferences, processes of shared decision-making should be implemented. Shared decision-making has the potential to reduce the rate of unnecessary interventions, and also improve the willingness of women to accept a medically-indicated caesarean section in low-income countries