University of Tennessee at Knoxville

This article reviews the historical progression of ventriculoperitoneal shunt valve designs with the goal of providing an understanding of their functionality and failure mechanisms. While shunting is the predominant treatment for hydrocephalus, the statistics of overall shunt failure remain high, and valve failure is responsible for a significant percentage of revision surgeries. Therefore, this review spans valve evolution from an engineering perspective with an emphasis on discussing potential failure mechanisms and patient-specific valve selection. Information is provided on the importance of valves in hydrocephalus treatment with discussion on each class of valves and their advantages and shortcomings. Substantial development over decades has significantly improved valve functionality, and ongoing research continues to provide more robust valves and shunt systems for hydrocephalus management.

The integer sequence π = π 1 ‧‧‧ π n is said to be an inversion sequence if 0 ≤ π i ≤ i – 1 for all i . Let ℐ n denote the set of inversion sequences of length n , represented using positive instead of non-negative integers. We consider here two new statistics defined on the bargraph representation b ( π ) of an inversion sequence π which record the number of unit squares touching the boundary of b ( π ) and that are either exterior or interior to b ( π ). We denote these statistics on ℐ n recording the number of outer and inner perimeter squares respectively by oper and iper. In this paper, we study the distribution of oper and iper on ℐ n and also on members of ℐ n that end in a particular letter. We find explicit formulas for the maximum and minimum values of oper and iper achieved by a member of ℐ n as well as for the average value of these parameters. We make use of both algebraic and combinatorial arguments in establishing our results.

Sub‐Ångstrom‐level porosity engineering, which is appealing in gas separations, has been demonstrated in solid carbon, polymer, and framework materials but rarely achieved in the liquid phase. In this work, a gas molecular sieving effect in the liquid phase at sub‐5 Ångstrom scale is created via sophisticated porosity tuning in calixarene‐derived porous liquids (PLs). Type II PLs are constructed via supramolecular complexation between the sodium salts of calixarene derivatives and crown ether solvents. The chemical structure variation and assembly behavior of the porous host upon PL construction are monitored by spectroscopy‐, X‐ray‐, and neutron‐scattering techniques. The presence of permanent porosity in calixarene‐derived PLs is verified by pressure swing gas uptake, altered CO2 physisorption behavior, and molecular simulations. Sub‐5 Ångstrom porosity tuning within the PL phase is achieved by introducing bulky substituted groups on the benzene ring of the calixarene host, which then greatly affects the dynamic motion and transport behavior of CO2 molecules and the Xe uptake performance. The approach being demonstrated in this work represents a promising pathway to tune and leverage the porosity effect for enhanced gas uptake capacity and selectivity in liquid sorbents.

Background Diabetes is an increasingly important public health problem due to its socioeconomic impact, high morbidity, and mortality. Although there is evidence of increasing diabetes-related deaths over the last ten years, little is known about the population level predictors of diabetes-related mortality risks (DRMR) in Florida. Identifying these predictors is important for guiding control programs geared at reducing the diabetes burden and improving population health. Therefore, the objective of this study was to identify geographic disparities and predictors of county-level DRMR in Florida. Methods The 2019 mortality data for the state of Florida were obtained from the Florida Department of Health. The 10th International Classification of Disease codes E10-E14 were used to identify diabetes-related deaths which were then aggregated to the county-level. County-level DRMR were computed and presented as number of deaths per 100,000 persons. Geographic distribution of DRMR were displayed in choropleth maps and ordinary least squares (OLS) regression model was used to identify county-level predictors of DRMR. Results There was a total 6,078 diabetes-related deaths in Florida during the study time period. County-level DRMR ranged from 9.6 to 75.6 per 100,000 persons. High mortality risks were observed in the northern, central, and southcentral parts of the state. Relatively higher mortality risks were identified in rural counties compared to their urban counterparts. Significantly high county-level DRMR were observed in counties with high percentages of the population that were: 65 year and older ( p < 0.001), current smokers ( p = 0.032), and insufficiently physically active ( p = 0.036). Additionally, percentage of households without vehicles ( p = 0.022) and percentage of population with diabetes ( p < 0.001) were significant predictors of DRMR. Conclusion Geographic disparities of DRMR exist in Florida, with high risks being observed in northern, central, and southcentral counties of the state. The study identified county-level predictors of these identified DRMR disparities in Florida. The findings are useful in guiding health professionals to better target intervention efforts.

Symmetrical wave ripples identified with NASA’s Curiosity rover in ancient lake deposits at Gale crater provide a key paleoclimate constraint for early Mars: At the time of ripple formation, climate conditions must have supported ice-free liquid water on the surface of Mars. These features are the most definitive examples of wave ripples on another planet. The ripples occur in two stratigraphic intervals within the orbitally defined Layered Sulfate Unit: a thin but laterally extensive unit at the base of the Amapari member of the Mirador formation, and a sandstone lens within the Contigo member of the Mirador formation. In both locations, the ripples have an average wavelength of ~4.5 centimeters. Internal laminae and ripple morphology show an architecture common in wave-influenced environments where wind-generated surface gravity waves mobilize bottom sediment in oscillatory flows. Their presence suggests formation in a shallow-water (<2 meters) setting that was open to the atmosphere, which requires atmospheric conditions that allow stable surface water.

Occupation is a construct prone to classification mismatches by coders and description inconsistency by respondents. We explore whether mismatches in occupational coding have recently increased, what factors are associated with the rise in mismatches, and how the rise affects estimates of intragenerational occupational mobility. Utilizing the 1991–2020 Annual Social and Economic Supplement of the Current Population Survey, which collects information on respondents’ current occupation and the previous year’s main occupation, we identify coding mismatches and compare the probabilities of occupational mobility based on four combinations of two variables. Our results show that not only do the estimates of occupational mobility between two adjacent years vary substantially across measures, but also that the magnitudes of intragenerational occupational mobility across measures become increasingly decoupled over time. We demonstrate that the likely cause of this divergence is the rise in coding mismatches between coders. We discuss the implications of our findings.

This study was to determine the effectiveness of augmented reality on phoneme and word reading for three first-grade students with developmental delays and autism in a self-contained elementary school classroom. Effectiveness of the intervention was evaluated with a multiple probe across word sets research design. An augmented reality iPad app was used to overlay video models for the process of reading decoding over a printed sheet for each word. The printed sheet contained triggers for separate videos showing reading of each individual phoneme, blending all phonemes together slowly, reading the word aloud, and defining the word. All participants increased their ability to read phonemes and words. Our findings have implications for teachers who want to use interactive technology to teach reading skills to young students with autism and developmental delay.

This study aimed to identify early risk factors experienced by youth with high-incidence disabilities (HID) and investigate their juvenile justice outcomes. Using statewide administrative data in a Midwestern U.S. state, this study identified that 9% of students ( n = 5,377) were diagnosed with an HID condition in the special education system. Latent class analysis revealed three meaningful subgroups of youth with HID, based on underlying patterns of early risks they experienced: low risk (47.6%), academic risk (37.5%), and child welfare risk (14.9%). These within-group differences accounted for the varying developmental outcomes among these youth. The odds were 4 times and 19 times higher for youth with HID in the Academic Risks and Child Welfare Risks class, respectively.

The perovskite type compounds of BaCe0.6–xZr0.3SmxPr0.1O3–δ (x = 0.1, 0.2, 0.3, and 0.4; named as BCZSP1, BCZSP2, BCZSP3, and BCZSP4, respectively) were synthesized by the dry chemistry reaction method. The structure, phase, microstructure, impedance spectroscopy and chemical stability of the synthesized compounds were investigated by different techniques. The XRD data of the materials showed the cubic crystal symmetry within the Pm–3m space group. The Chekcell and WinXPow software were used to index the crystal symmetry and space group of the XRD data and the FullProf suite software was utilized to carry out the Rietveld refinements of the acquired XRD data. The scanning electron microscopy (SEM) was used to examine the grain morphology and grain growth of the materials, and the SEM results indicate that all of the materials had densities more than 97% of the theoretical density. The thermogravimetric analysis (TGA) of the materials in the CO2 gas atmosphere exhibited superior stability. The protonic conductivity was found the highest in the wet 5% H2 in argon (Ar) gas environment for the BCZSP1 (x = 0.10) material and were ~1.19 × 10–2 and ~1.03 × 10–2 S cm–1 at 650 and 700°C, respectively. The highest stability was for BCZSP4 in the CO2 gas environment for the four samples of the BCZSP series. At intermediate temperatures (500–700°C), the materials show potential electrolyte behavior for applications in solid oxide fuel cell that transport protons.

Brain‐inspired (or neuromorphic) computing circumvents costly bottlenecks in conventional Von Neumann architectures by collocating memory and processing. This is accomplished through dynamic material architectures, strengthening or weakening internal conduction pathways similar to synaptic connections within the brain. A new class of neuromorphic materials approximates synaptic interfaces using lipid membranes assembled via the droplet interface bilayer (DIB) technique. These DIB membranes have been studied as novel memristors or memcapacitors owing to the soft, reconfigurable nature of both the lipid membrane geometry and the embedded ion‐conducting channels. In this work, a biomolecular approach to neuromorphic materials is expanded from model synapses to a charge‐integrating model neuron. In these serial membrane networks, it is possible to create distributions of voltage‐sensitive gates capable of trapping ionic charge. This trapped charge creates transmembrane potential differences that drive changes in the system's net capacitance through electrowetting, providing a synaptic weight that changes in response to the history and timing of input signals. This fundamental change from interfacial memory (dimensions of the membrane) to internal memory (charge trapped within the droplets) provides a functional plasticity capable of multiple weights, longer‐term retention roughly an order of magnitude greater than memory stored in the membranes alone, and programming‐erasure.