Thermal And Mechanical Response Of Particulate Composite Plates Under Inertial Excitation

The thermal and mechanical, near-resonant responses of particulate composite plates formed from hydroxyl-terminated polybutadiene (HTPB) binder and varying volume ratios of ammonium chloride (NH4Cl) particles (50, 65, 75%) are investigated. Each test specimen is clamped and forced with three levels of band-limited, white noise inertial excitation (10–1000 Hz at 1.00, 1.86 and 2.44 g RMS). The mechanical response of each plate is recorded via scanning laser Doppler vibrometry. The plates are then excited at a single resonant frequency and the thermal response is recorded via infrared thermography. Comparisons are made between the mechanical operational deflection shapes of each plate and spatial temperature distributions, with correlation seen between the observed level of strain, as visualized by strain energy density, and heat generation. The effect of particle/binder ratio on both the thermal and mechanical responses is discussed. Acquired results are also compared to an analytical model of the system. The observed thermomechanical effects render an improved understanding of the thermomechanics of plastic-bonded composites, an essential step in support of the development of new technologies for the vapor-based detection of hidden explosives

Experimental Measurements of Binder Wave Speeds using Wavenumber Decomposition

Prior work has provided few wave speed measurements for the binder materials commonly used with plastic- bonded energetics. Furthermore, those measurements that have been reported are largely based upon rudimentary, \u27pitch and catch\u27 methodologies, which involve sending a pulse from one transducer to another transducer at a set distance apart and measuring the time of flight. Given this, a more rigorous method for determining longitudinal and shear wave speeds in this important class of materials was desired. In this work, material wave speeds are recovered by measuring the vibrational response of a 2D line across the surface of a beam in response to a mechanical excitation and analyzing the data in the frequency-wavenumber domain

Association between Depression and Aggression in Rural Women

Rural women represent approximately 20% of women living in the United States, yet research on the specific mental health needs of rural women is limited. Given the well-recognized gender-linked disparity in depression, its correlated symptoms in women still need much investigation. While emerging notions of depression in men embrace potential symptoms related to irritability and aggression, less research has focused on the potential role of aggression in depressed women. This connection may be particularly relevant for rural women who face unique mental health stressors in comparison to their urban counterparts. The purpose of this study was to examine if aggression is linked to depression for rural women in order to identify potential unique symptomatology and presentation for rural women. As part of a larger initiative, a sample of 54 participants was recruited from the patient population at a Federally Qualified Health Center (FQHC) in rural southeast Georgia to participate in a quantitative survey. The survey assessed demographics, depression, and aggressive behavior. Mean total score of aggression in depressed women was significantly higher than non-depressed women (p \u3c 0.001), and within the entire sample depression scores were significantly related linearly to aggression, explaining 16% of the variance found in depression scores (β = .399, r2 = .159, p = 0.003). This study suggests that aggressive behavior may be linked to depression for rural women, and underscores the need for future research investigating if depression presents differently for rural women

Lubricating Bacteria Model for Branching growth of Bacterial Colonies

Various bacterial strains (e.g. strains belonging to the genera Bacillus, Paenibacillus, Serratia and Salmonella) exhibit colonial branching patterns during growth on poor semi-solid substrates. These patterns reflect the bacterial cooperative self-organization. Central part of the cooperation is the collective formation of lubricant on top of the agar which enables the bacteria to swim. Hence it provides the colony means to advance towards the food. One method of modeling the colonial development is via coupled reaction-diffusion equations which describe the time evolution of the bacterial density and the concentrations of the relevant chemical fields. This idea has been pursued by a number of groups. Here we present an additional model which specifically includes an evolution equation for the lubricant excreted by the bacteria. We show that when the diffusion of the fluid is governed by nonlinear diffusion coefficient branching patterns evolves. We study the effect of the rates of emission and decomposition of the lubricant fluid on the observed patterns. The results are compared with experimental observations. We also include fields of chemotactic agents and food chemotaxis and conclude that these features are needed in order to explain the observations.Comment: 1 latex file, 16 jpeg files, submitted to Phys. Rev.

Proteomic analysis of the \u3cem\u3eS. cerevisiae\u3c/em\u3e response to the anticancer ruthenium complex KP1019

Like platinum-based chemotherapeutics, the anticancer ruthenium complex indazolium trans-[tetrachlorobis(1H-indazole)ruthenate(iii)], or KP1019, damages DNA, induces apoptosis, and causes tumor regression in animal models. Unlike platinum-based drugs, KP1019 showed no dose-limiting toxicity in a phase I clinical trial. Despite these advances, the mechanism(s) and target(s) of KP1019 remain unclear. For example, the drug may damage DNA directly or by causing oxidative stress. Likewise, KP1019 binds cytosolic proteins, suggesting DNA is not the sole target. Here we use the budding yeast Saccharomyces cerevisiae as a model in a proteomic study of the cellular response to KP1019. Mapping protein level changes onto metabolic pathways revealed patterns consistent with elevated synthesis and/or cycling of the antioxidant glutathione, suggesting KP1019 induces oxidative stress. This result was supported by increased fluorescence of the redox-sensitive dye DCFH-DA and increased KP1019 sensitivity of yeast lacking Yap1, a master regulator of the oxidative stress response. In addition to oxidative and DNA stress, bioinformatic analysis revealed drug-dependent increases in proteins involved ribosome biogenesis, translation, and protein (re)folding. Consistent with proteotoxic effects, KP1019 increased expression of a heat-shock element (HSE) lacZ reporter. KP1019 pre-treatment also sensitized yeast to oxaliplatin, paralleling prior research showing that cancer cell lines with elevated levels of translation machinery are hypersensitive to oxaliplatin. Combined, these data suggest that one of KP1019’s many targets may be protein metabolism, which opens up intriguing possibilities for combination therapy

On the Thermomechanical Response of HTPB-Based Composite Beams Under Near-Resonant Excitation

Currently, there is a pressing need to detect and identify explosive materials in both military and civilian settings. While these energetic materials vary widely in both form and composition, many traditional explosives consist of a polymeric binder material with embedded energetic crystals. Interestingly, many polymers exhibit considerable self-heating when subjected to harmonic loading, and the vapor pressures of many explosives exhibit a strong dependence on temperature. In light of these facts, thermomechanics represent an intriguing pathway for the stand-off detection of explosives, as the thermal signatures attributable to motion-induced heating may allow target energetic materials to be distinguished from their more innocuous counterparts. In the present work, the thermomechanical response of a sample from this class of materials is studied in depth. Despite the nature of the material as a polymer-based particulate composite, classical Euler-Bernoulli beam theory, along with the complex modulus representation for linear viscoelastic materials, was observed to yield predictions of the thermal and mechanical responses in agreement with experimental investigations. The results of the experiments conducted using a hydroxyl-terminated polybutadiene (HTPB) beam with embedded ammonium chloride (NH 4 Cl) crystals are presented. Multiple excitation levels are employed and the results are subsequently compared to the work's analytical findings

The yeast homologue of the microtubule-associated protein Lis1 interacts with the sumoylation machinery and a SUMO-targeted ubiquitin ligase

Microtubules and microtubule-associated proteins are fundamental for multiple cellular processes, including mitosis and intracellular motility, but the factors that control microtubule-associated proteins (MAPs) are poorly understood. Here we show that two MAPs - the CLIP-170 homologue Bik1p and the Lis1 homologue Pac1p - interact with several proteins in the sumoylation pathway. Bik1p and Pac1p interact with Smt3p, the yeast SUMO; Ubc9p, an E2; and Nfi1p, an E3. Bik1p interacts directly with SUMO in vitro, and overexpression of Smt3p and Bik1p results in its in vivo sumoylation. Modified Pac1p is observed when the SUMO protease Ulp1p is inactivated. Both ubiquitin and Smt3p copurify with Pac1p. In contrast to ubiquitination, sumoylation does not directly tag the substrate for degradation. However, SUMO-targeted ubiquitin ligases (STUbLs) can recognize a sumoylated substrate and promote its degradation via ubiquitination and the proteasome. Both Pac1p and Bik1p interact with the STUbL Nis1p-Ris1p and the protease Wss1p. Strains deleted for RIS1 or WSS1 accumulate Pac1p conjugates. This suggests a novel model in which the abundance of these MAPs may be regulated via STUbLs. Pac1p modification is also altered by Kar9p and the dynein regulator She1p. This work has implications for the regulation of dynein\u27s interaction with various cargoes, including its off-loading to the cortex. © 2012 Alonso et al

Comparing the Safety and Efficacy of a Rapid High-Sensitivity Cardiac Troponin I Protocol Between Hospital-Based and Free-Standing Emergency Departments

Study Objectives: Current high sensitivity cardiac troponin I (hs-cTnI) research has been conducted almost exclusively in hospital-based emergency department (HBED) settings and the translation of these protocols into free-standing emergency departments (FSED) has yet to be explored. This study compared the safety and efficacy of applying a rapid-rule out protocol using hs-cTnI for exclusion of acute myocardial infarction (AMI) in HBEDs and FSEDs. Methods: This was a secondary analysis of a randomized trial of patients evaluated for possible AMI in 9 emergency departments (ED) from July 2020 through March 2021. The trial arms included a new 0/1-hour rapid protocol using hs-cTnI versus standard care, which used a 0/3-hour protocol without reporting hs-cTnI values below the 99th percentile. The primary outcome was safe ED discharge, defined as discharge with no death or AMI within 30-days. Analysis included a mixed-effect model adjusting for demographic variables. Results: There was a statistically significant difference in safe discharges from FSEDs when comparing the standard care arm (86.2%) to the rapid rule-out protocol (95.1%). There was a statistically significant reduction in FSED length of stay with application of a rapid rule-out protocol at 3.43 hours vs. 3.97 hours using standard care. The percentage of patients who ruled-out with their initial hs-cTnI (\u3c4 ng/L) at FSEDs (74%) was also significantly larger when compared to HBEDs (54%). Conclusion: Implementation of a hs-cTnI rapid 0/1-hour protocol to evaluate for AMI in FSEDs is feasible and had greater impact on safe ED discharge and length of stay compared to HBEDs