Grandmothers residing with grandchildren: Social determinants of health, health behaviors, and health outcomes.

The purpose of this study was to explore the associations between social determinants of health, health behaviors, and physical and mental health among African American and Hispanic caregiving grandmothers. We use cross-sectional secondary data from the Chicago Community Adult Health Study, originally designed to understand the health of individual households based on residential context. In a multivariate regression model, discrimination, parental stress, and physical health problems were significantly associated with depressive symptoms in caregiving grandmothers. Considering the multiple sources of stress experienced by this grandmother sample, researchers should develop and strengthen contextually relevant interventions for improving the health of caregiving grandmothers. Healthcare providers must be equipped with skills to address caregiving grandmothers' unique needs related to stress. Finally, policy makers should promote the development of legislation that can positively influence caregiving grandmothers and their families. Expanding the lens through which caregiving grandmothers living in minoritized communities are viewed can catalyze meaningful change.

MoSDeF-GOMC: Python Software for the Creation of Scientific Workflows for the Monte Carlo Simulation Engine GOMC.

MoSDeF-GOMC is a python interface for the Monte Carlo software GOMC to the Molecular Simulation Design Framework (MoSDeF) ecosystem. MoSDeF-GOMC automates the process of generating initial coordinates, assigning force field parameters, and writing coordinate (PDB), connectivity (PSF), force field parameter, and simulation control files. The software lowers entry barriers for novice users while allowing advanced users to create complex workflows that encapsulate simulation setup, execution, and data analysis in a single script. All relevant simulation parameters are encoded within the workflow, ensuring reproducible simulations. MoSDeF-GOMC's capabilities are illustrated through a number of examples, including prediction of the adsorption isotherm for CO2 in IRMOF-1, free energies of hydration for neon and radon over a broad temperature range, and the vapor-liquid coexistence curve of a four-component surrogate for the jet fuel S-8. The MoSDeF-GOMC software is available on GitHub at https://github.com/GOMC-WSU/MoSDeF-GOMC.

MoSDeF Cassandra: A complete Python interface for the Cassandra Monte Carlo software.

We introduce a new Python interface for the Cassandra Monte Carlo software, molecular simulation design framework (MoSDeF) Cassandra. MoSDeF Cassandra provides a simplified user interface, offers broader interoperability with other molecular simulation codes, enables the construction of programmatic and reproducible molecular simulation workflows, and builds the infrastructure necessary for high-throughput Monte Carlo studies. Many of the capabilities of MoSDeF Cassandra are enabled via tight integration with MoSDeF. We discuss the motivation and design of MoSDeF Cassandra and proceed to demonstrate both simple use-cases and more complex workflows, including adsorption in porous media and a combined molecular dynamics - Monte Carlo workflow for computing lateral diffusivity in graphene slit pores. The examples presented herein demonstrate how even relatively complex simulation workflows can be reduced to, at most, a few files of Python code that can be version-controlled and shared with other researchers. We believe this paradigm will enable more rapid research advances and represents the future of molecular simulations.

Incorporating configurational-bias Monte Carlo into the Wang-Landau algorithm for continuous molecular systems.

Configurational-bias Monte Carlo has been incorporated into the Wang-Landau method. Although the Wang-Landau algorithm enables the calculation of the complete density of states, its applicability to continuous molecular systems has been limited to simple models. With the inclusion of more advanced sampling techniques, such as configurational-bias, the Wang-Landau method can be used to simulate complex chemical systems. The accuracy and efficiency of the method is assessed using as a test case systems of linear alkanes represented by a united-atom model. With strict convergence criteria, the density of states derived from the Wang-Landau algorithm yields the correct heat capacity when compared to conventional Boltzmann sampling simulations.

A Wang-Landau study of a lattice model for lipid bilayer self-assembly.

The Wang-Landau (WL) Monte Carlo method has been applied to simulate the self-assembly of a lipid bilayer on a 3D lattice. The WL method differs from conventional Monte Carlo methods in that a complete density of states is obtained directly for the system, from which properties, such as the free energy, can be derived. Furthermore, from a single WL simulation, continuous curves of the average energy and heat capacity can be determined, which provide a complete picture of the phase behavior. The lipid model studied consists of 3 or 5 coarse-grained segments on lattices of varying sizes, with the empty lattice sites representing water. A bilayer structure is found to form at low temperatures, with phase transitions to clusters as temperature increases. For 3-segment chains, varying lattice sizes were studied, with the observation that the ratio of chain number to lattice area (i.e., area per lipid) affects the phase transition temperature. At small ratios, only one phase transition occurs between the bilayer and cluster phases, while at high lipid ratios the phase transition occurs in a two-step process with a stable intermediate phase. This second phase transition was not observed in conventional Metropolis Monte Carlo simulations on the same model, demonstrating the advantage of being able to perform a complete scan of the whole temperature range with the WL method. For longer 5-segment chains similar phase transitions are also observed with changes in temperature. In the WL method, due to the extensive nature of the energy, the number of energy bins required to represent the density of states increases as the system size increases and so limits its practical application to larger systems. To improve this, an extension of the WL algorithm, the statistical-temperature Monte Carlo method that allows simulations with larger energy bin sizes, has recently been proposed and is implemented in this work for the 3-segment lattice model. The results obtained are in good agreement with the original WL method and appear to be independent of the energy bin size used.

Neuroimaging assessment of memory-related brain structures in a rat model of acute space-like radiation.

PURPOSE: To investigate the acute effects on the central nervous system (CNS) of (56)Fe radiation, a component of high-energy charged particles (HZE) in space radiation, using quantitative magnetic resonance imaging (MRI) noninvasively. MATERIALS AND METHODS: Sprague-Dawley rats were exposed to whole-brain (56)Fe (0, 1, 2, and 4 Gy). At 1 week postirradiation, MRI scans were made using T2-weighted (T2WI), diffusion-weighted (DWI), and contrast enhanced T1-(CET1) imaging. T2 relaxation time and apparent diffusion coefficient (ADC) values were obtained from memory-related brain regions of interest (ROIs). Histopathology was correlated using ex vivo tissues. RESULTS: No overt abnormalities were visualized using T2WI and DWI at 1 week postradiation. CET1 values did not differ significantly between the irradiated and control animals. Compared to 0 Gy, there were significant prolongations in T2 values and reductions in ADC after irradiation. In the absence of evident neuronal pathology, immunohistochemistry revealed astrocytic activation in 4 Gy animals. CONCLUSION: At 1 week after whole-brain (56)Fe exposure, T2 and ADC values can differentiate radiosensitivity in regions critical for hippocampal-related memory. MRI may provide noninvasive assessment of the initial molecular/cellular disturbances in vivo after HZE irradiation.

Self-assembly of 1,4-benzenedithiolate/tetrahydrofuran on a gold surface: a Monte Carlo simulation study.

We report a Monte Carlo simulation study of the self-assembly of 1,4-benzenedithiolate (BDT), tetrahydrofuran (THF), and their mixtures on a Au (111) surface. We use the grand canonical Monte Carlo method to obtain the equilibrium adsorption coverage. Canonical ensemble (NVT) simulation is then used to explore further the structural information of the equilibrated systems. Our results indicate that BDT molecules adsorb onto the Au (111) surface with one of the sulfur atoms bonded to Au atoms. THF molecules form clusters on the surface. For BDT-THF mixtures, BDT can selectively adsorb on Au (111) to form a monolayer, whereas the solvent THF molecules either float above BDT monolayer or occupy vacancies on the surface that are not covered by BDT molecules. BDT molecules adsorb on a Au (111) surface with an average tilt angle of about 18-35 degrees to the surface normal. The tilting angle decreases as the coverage increases. In addition, the BDT monolayer constitutes an ordered herringbone structure on the Au (111) surface, and the ordering pattern is insensitive to the BDT coverage. In comparison, the THF molecules exhibit amorphous structure on the Au surface. Interestingly, simulations indicate that the bonding behavior of BDT molecules on Au (111) is coverage-dependent. BDT bonds preferably on the Au top site when the surface coverage is low. As coverage increases, most BDT molecules bond on the bridge and fcc hollow sites.

Association of hospital trauma designation with admission patterns of injured children.

BACKGROUND: Little is known about the influence of regionalization of trauma care on pediatric trauma care delivery. The purpose of this study was to estimate whether formal adoption of a statewide trauma system was associated with hospital admission patterns of injured children. METHODS: A longitudinal study of children who were residents of Washington State during 1989 to 1999 was conducted. The main outcome measure was hospital admission for trauma. RESULTS: During the 11-year period, there were 24,955 admissions. Admission rates of injured children to pediatric-designated trauma hospitals decreased by 20%, rates at adult-designated hospitals decreased by 60%, and rates at nondesignated hospitals decreased by 66%. Introduction of the trauma system in 1994 was associated with a 12% increase in admission rates to pediatric-designated hospitals, little change (+1%) in admission rates to adult-designated centers, and an 11% decrease in admissions at nondesignated hospitals. CONCLUSION: Trauma designation in Washington was associated with a shift in admissions from nondesignated hospitals to pediatric trauma hospitals.

Assessment of volume of hemorrhage and outcome from pelvic fracture.

HYPOTHESIS: Measurement of pelvic hemorrhage on computed tomographic (CT) scans can estimate the pelvic fracture component of total patient blood loss and predict the need for angiography. DESIGN: Retrospective cohort study. SETTING: Large level 1 trauma center. PATIENTS: We examined data from 759 consecutive, nonreferral blunt trauma patients who sustained pelvic fracture. MAIN OUTCOME MEASURES: Pelvic-fracture-specific outcomes included estimation of extraperitoneal pelvic hemorrhage volume from emergency department CT scans and determination of arterial injury from angiograms. General patient outcomes determined from medical record review included transfusion requirement, estimated blood loss, and mortality. Subanalysis was performed on subjects with only pelvic fracture as a source of major hemorrhage (derived from discharge International Classification of Diseases, Ninth Revision, Clinical Modification codes). RESULTS: Overall mortality was 96 (13%) of 759 patients. Blood transfusion was given to 418 (55%) patients, and 258 (34%) received 6 or more units in the first 72 hours. Pelvic-fracture-related hemorrhage averaged 149 mL (range, 0-1423 mL). Angiography was performed on 163 patients, of whom 113 had arterial injury. Higher pelvic hemorrhage volumes on CT scans were seen in subjects with pelvic arterial injury demonstrated on angiograms (P<.001). In subjects without another source of major hemorrhage, pelvic CT hemorrhage volumes were strongly associated with transfusion requirement (P<.001). Subjects with large pelvic hemorrhage volumes (>500 mL) were more likely to have pelvic arterial injury (risk ratio, 4.8; 95% confidence interval, 3.0-7.8; P<.001) and require large-volume (>/=6 U) transfusions (risk ratio, 4.7; 95% confidence interval, 1.8-12.3; P<.001) than patients with smaller pelvic hemorrhage volumes. CONCLUSION: Pelvic hemorrhage volumes derived from pelvic CT scans were predictors of the need for pelvic arteriography and transfusions.