The Neurodynamics of Working Memory During a Stress Induced State

Purpose: Currently the mechanisms the brain uses for various processes are not well understood; the bio-electrical system is complex. The purpose of the current study is to measure the electrical activity of the brain during a working memory task pre- and post-stressor. Method: The participants’ negative affect (PANAS; Watson, Clark, & Tellegen, 1988), and stress (SRQ; Edwards, Edwards, & Lyvers, 2015) scores were measured after the baseline, after the stressor tasks, and at the end of the study. EEG data was collected during a baseline, a working memory task pre-stressor condition, and a working memory task post-stressor condition. Results: Results indicated no significant interaction between Time x Location x Band. However, there was marginal significance at the Time x Band interaction level, providing marginal support for the idea that the brain enters different band wave frequencies for different tasks, and while in different emotional states. During each time condition, there was a decrease in alpha compared to the preceding time condition. A further look showed marginal significance at the band level, and found significance at the location level. The analysis on the median reaction time during the pre-modified Sternberg working memory task (pre-MSWM) and post-modified Sternberg working memory task (post-MSWM) conditions was marginally significant. There was a decrease in median reaction during the post-MSWM condition compared to the pre-MSWM condition. Further, there was marginal significance in the alpha amplitude between location Fp1 and Fp2 during the post-MSWM condition. Alpha was highest at location Fp1 during both the pre- and post-MSWM conditions. Alpha asymmetry decreased in the post-MSWM condition compared to the pre-MSWM condition. Conclusion: There was a decrease in alpha during each time condition compared to the preceding time condition. The alpha asymmetry pattern was consistent with previous studies in individuals with chronic stress. There was as decreased in median reaction time during the post-MSWM condition compared to the pre-MSWM condition, which is inverse of what was expected. This could possibly be explained by the participants reaching a peak performance level on the stress-performance curve, there could have been a practice effect that occurred, or possibly a combination of both. Limits on sample size greatly reduced the power of this study. It would be beneficial to conduct similar studies that could aid in understanding the mechanisms the brain uses during various processes.http://deepblue.lib.umich.edu/bitstream/2027.42/135711/1/Bryant - Neurodynamics of Working Memory During a Stressed Induced State.pdf13Description of Bryant - Neurodynamics of Working Memory During a Stressed Induced State.pdf : Master's Thesi

Optimal Data Split Methodology for Model Validation

The decision to incorporate cross-validation into validation processes of mathematical models raises an immediate question - how should one partition the data into calibration and validation sets? We answer this question systematically: we present an algorithm to find the optimal partition of the data subject to certain constraints. While doing this, we address two critical issues: 1) that the model be evaluated with respect to predictions of a given quantity of interest and its ability to reproduce the data, and 2) that the model be highly challenged by the validation set, assuming it is properly informed by the calibration set. This framework also relies on the interaction between the experimentalist and/or modeler, who understand the physical system and the limitations of the model; the decision-maker, who understands and can quantify the cost of model failure; and the computational scientists, who strive to determine if the model satisfies both the modeler's and decision maker's requirements. We also note that our framework is quite general, and may be applied to a wide range of problems. Here, we illustrate it through a specific example involving a data reduction model for an ICCD camera from a shock-tube experiment located at the NASA Ames Research Center (ARC).Comment: Submitted to International Conference on Modeling, Simulation and Control 2011 (ICMSC'11), San Francisco, USA, 19-21 October, 201

Adaptive surrogate modeling for response surface approximations with application to bayesian inference

ABSTRACT: Parameter estimation for complex models using Bayesian inference is usually a very costly process as it requires a large number of solves of the forward problem. We show here how the construction of adaptive surrogate models using a posteriori error estimates for quantities of interest can significantly reduce the computational cost in problems of statistical inference. As surrogate models provide only approximations of the true solutions of the forward problem, it is nevertheless necessary to control these errors in order to construct an accurate reduced model with respect to the observables utilized in the identification of the model parameters. Effectiveness of the proposed approach is demonstrated on a numerical example dealing with the Spalart–Allmaras model for the simulation of turbulent channel flows. In particular, we illustrate how Bayesian model selection using the adapted surrogate model in place of solving the coupled nonlinear equations leads to the same quality of results while requiring fewer nonlinear PDE solve

Identification of Enhancer of Zeste Homolog 2 Expression in Peripheral Circulating Tumor Cells in Metastatic Prostate Cancer Patients: A Preliminary Study

transcriptional repressor, is reportedly over-expressed in metastatic prostate cancer. In this study, we analyzed EZH2 mRNA in circulating tumor cells (CTCs) in peripheral blood as a biomarker in patients with metastatic prostate cancer. Patients and Methods: Ber-EP4 coated immunomagnetic beads were used to harvest CTCs, and mRNA was isolated by oligodT conjugated immunomagnetic beads. Reverse transcriptasepolymerase chain reaction for EZH2 mRNA was performed and the expression density was measured. The sensitivity of this test for detection of EZH2 mRNA was determined by serial dilutions of a human prostate cancer cell line. Blood samples were collected from 20 patients each with metastatic or localized prostate cancer and 10 healthy volunteers. Results: Sensitivity experiments showed that the test was highly sensitive as it could detect 10 tumor cells per 5 mL. EZH2 mRNA expression was obtained from peripheral blood samples of patients and control subjects. EZH2 mRNA expression density in the metastatic prostate cancer group was significantly higher than in the control (p = 0.023) and localized prostate cancer groups (p = 0.019). There was no difference between the control and localized prostate cancer groups (p> 0.05). Conclusion: EZH2 mRNA expression in circulating epithelial cells represents a promising marker for detecting early metastasis in prostate cancer. However, more specific and sensitive techniques for detection of CTCs are needed to avoid mononuclear cell contamination

The SWI/SNF complex acts to constrain distribution of the centromeric histone variant Cse4

In order to gain insight into the function of the Saccharomyces cerevisiae SWI/SNF complex, we have identified DNA sequences to which it is bound genomewide. One surprising observation is that the complex is enriched at the centromeres of each chromosome. Deletion of the gene encoding the Snf2 subunit of the complex was found to cause partial redistribution of the centromeric histone variant Cse4 to sites on chromosome arms. Cultures of snf2Δ yeast were found to progress through mitosis slowly. This was dependent on the mitotic checkpoint protein Mad2. In the absence of Mad2, defects in chromosome segregation were observed. In the absence of Snf2, chromatin organisation at centromeres is less distinct. In particular, hypersensitive sites flanking the Cse4 containing nucleosomes are less pronounced. Furthermore, SWI/SNF complex was found to be especially effective in the dissociation of Cse4 containing chromatin in vitro. This suggests a role for Snf2 in the maintenance of point centromeres involving the removal of Cse4 from ectopic sites

The TESS-Keck Survey II: An Ultra-Short Period Rocky Planet and its Siblings Transiting the Galactic Thick-Disk Star TOI-561

We report the discovery of TOI-561, a multi-planet system in the galactic thick disk that contains a rocky, ultra-short period planet (USP). This bright ($V=10.2$) star hosts three small transiting planets identified in photometry from the NASA TESS mission: TOI-561 b (TOI-561.02, P=0.44 days, $R_b = 1.45\pm0.11\,R_\oplus$), c (TOI-561.01, P=10.8 days, $R_c=2.90\pm0.13\,R_\oplus$), and d (TOI-561.03, P=16.3 days, $R_d=2.32\pm0.16\,R_\oplus$). The star is chemically ([Fe/H]$=-0.41\pm0.05$, [$\alpha$/H]$=+0.23\pm0.05$) and kinematically consistent with the galactic thick disk population, making TOI-561 one of the oldest ($10\pm3\,$Gyr) and most metal-poor planetary systems discovered yet. We dynamically confirm planets b and c with radial velocities from the W. M. Keck Observatory High Resolution Echelle Spectrometer. Planet b has a mass and density of $3.2\pm0.8\,M_\oplus$ and $5.5^{+2.0}_{-1.6}\,$g$\,$cm$^{-3}$, consistent with a rocky composition. Its lower-than-average density is consistent with an iron-poor composition, although an Earth-like iron-to-silicates ratio is not ruled out. Planet c is $7.0\pm2.3\,M_\oplus$ and $1.6\pm0.6\,$g$\,$cm$^{-3}$, consistent with an interior rocky core overlaid with a low-mass volatile envelope. Several attributes of the photometry for planet d (which we did not detect dynamically) complicate the analysis, but we vet the planet with high-contrast imaging, ground-based photometric follow-up and radial velocities. TOI-561 b is the first rocky world around a galactic thick-disk star confirmed with radial velocities and one of the best rocky planets for thermal emission studies.Comment: Accepted at The Astronomical Journal; 25 pages, 10 figure

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Maintaining agronomics, economics, and furrow-irrigation efficiency in mid-southern USA soybean conservation production systems

Mid-southern USA soybean [Glycine max (L.) Merr.] producers are being pushed to increase adoption of conservation tillage systems as a means of increasing the application efficiency of gravity flow irrigation systems. This research was conducted to determine whether the efficiency of furrow-irrigation systems could be manipulated through conservation tillage systems while maintaining soybean productivity and profitability. Three experiments were conducted near Stoneville, MS on a Dubbs silt loam (Fine-silty, mixed, active, thermic Typic Hapludalfs) to determine the effects of reducing tillage and increasing ground cover residues on irrigation application efficiency, irrigation water use efficiency, soybean grain yield, and net returns above specified costs. In experiment 1, transitioning from conventional tillage to a conservation tillage system had no adverse effect on irrigation application efficiency, irrigation water use efficiency, soybean grain yield, or net returns above specified costs when subsoiling was included. For experiment 2, replacing subsoiling with a cereal rye or tillage radish cover crop in a conservation tillage system either had no effect or reduced irrigation application efficiency, irrigation water use efficiency, soybean grain yield, and net returns above specified costs up to 41%. In experiment 3, independent of cover crop, reducing tillage to only furrow creation had no adverse effect on irrigation application efficiency, irrigation water use efficiency, soybean grain yield, and net returns above specified costs relative to a conservation tillage system with subsoiling. Conservation tillage systems that include subsoiling maximize irrigation application efficiency and irrigation water use efficiency while minimizing adverse effects on yield and net returns relative to conservation tillage systems that further reduce tillage and/or increase ground coverage with cover crops. Our data indicate that soybean producers in the mid-southern USA maximize furrow-irrigation functionality, yield, and profitability while minimizing risk by transitioning from a conventional tillage system to a conservation tillage system with subsoiling