The Effects of Personality on Intertemporal Choice

This dissertation attempts to unveil new information concerning intertemporal choice, by trying to find a correlation between personality and the temporal choices that people make. The methodology for doing so is as follows: a survey was distributed and responses were regressed using Ordinary Least Squares (OLS). Given that there were two questions (one formatted using a calendar date and the other using a word format) about intertemporal choice (subjects were asked to choose a certain payoff corresponding to a specific point in time), there were two models constructed. Each model had the following variable structure: the dependent variable was the expected payoff, while the independent variables were gender, grade, and most importantly, the point total corresponding to the questions about personality. The results of the regression were not statistically significant, most likely majorly due to the smaller sample size of 204 observations as well as a possible presence of a sample bias of college students; however, interesting coefficient sign changes in gender and grade occurred between the two models. Furthermore, the coefficient sign on both models for the point total variable was negative, showing that the more self-interested someone is (according to a personality test), the more present-gain oriented they seem to be. A repetition of the experiment on a grander scale will either confirm or deny these variables’ role in deciding expected payoffs involving intertemporal choices

Contrast, contours and the confusion effect in dazzle camouflage

‘Motion dazzle camouflage’ is the name for the putative effects of highly conspicuous, often repetitive or complex, patterns on parameters important in prey capture, such as the perception of speed, direction and identity. Research into motion dazzle camouflage is increasing our understanding of the interactions between visual tracking, the confusion effect and defensive coloration. However, there is a paucity of research into the effects of contrast on motion dazzle camouflage: is maximal contrast a prerequisite for effectiveness? If not, this has important implications for our recognition of the phenotype and understanding of the function and mechanisms of potential motion dazzle camouflage patterns. Here we tested human participants' ability to track one moving target among many identical distractors with surface patterns designed to test the influence of these factors. In line with previous evidence, we found that targets with stripes parallel to the object direction of motion were hardest to track. However, reduction in contrast did not significantly influence this result. This finding may bring into question the utility of current definitions of motion dazzle camouflage, and means that some animal patterns, such as aposematic or mimetic stripes, may have previously unrecognized multiple functions

Dazzle camouflage, target tracking, and the confusion effect

The influence of coloration on the ecology and evolution of moving animals in groups is poorly understood. Animals in groups benefit from the “confusion effect,” where predator attack success is reduced with increasing group size or density. This is thought to be due to a sensory bottleneck: an increase in the difficulty of tracking one object among many. Motion dazzle camouflage has been hypothesized to disrupt accurate perception of the trajectory or speed of an object or animal. The current study investigates the suggestion that dazzle camouflage may enhance the confusion effect. Utilizing a computer game style experiment with human predators, we found that when moving in groups, targets with stripes parallel to the targets’ direction of motion interact with the confusion effect to a greater degree, and are harder to track, than those with more conventional background matching patterns. The findings represent empirical evidence that some high-contrast patterns may benefit animals in groups. The results also highlight the possibility that orientation and turning may be more relevant in the mechanisms of dazzle camouflage than previously recognized

Transcriptional networks specifying homeostatic and inflammatory programs of gene expression in human aortic endothelial cells.

Endothelial cells (ECs) are critical determinants of vascular homeostasis and inflammation, but transcriptional mechanisms specifying their identities and functional states remain poorly understood. Here, we report a genome-wide assessment of regulatory landscapes of primary human aortic endothelial cells (HAECs) under basal and activated conditions, enabling inference of transcription factor networks that direct homeostatic and pro-inflammatory programs. We demonstrate that 43% of detected enhancers are EC-specific and contain SNPs associated to cardiovascular disease and hypertension. We provide evidence that AP1, ETS, and GATA transcription factors play key roles in HAEC transcription by co-binding enhancers associated with EC-specific genes. We further demonstrate that exposure of HAECs to oxidized phospholipids or pro-inflammatory cytokines results in signal-specific alterations in enhancer landscapes and associate with coordinated binding of CEBPD, IRF1, and NFκB. Collectively, these findings identify cis-regulatory elements and corresponding trans-acting factors that contribute to EC identity and their specific responses to pro-inflammatory stimuli

Control of Candida albicans Metabolism and Biofilm Formation by Pseudomonas aeruginosa Phenazines

Candidaalbicanshasdevelopmentalprogramsthatgoverntransitionsbetweenyeastandfilamentousmorphologies and between unattached and biofilm lifestyles. Here, we report that filamentation, intercellular adherence, and biofilm develop- ment were inhibited during interactions between Candida albicans and Pseudomonas aeruginosa through the action of P. aeruginosa-produced phenazines. While phenazines are toxic to C. albicans at millimolar concentrations, we found that lower concentrations of any of three different phenazines (pyocyanin, phenazine methosulfate, and phenazine-1-carboxylate) allowed growth but affected the development of C. albicans wrinkled colony biofilms and inhibited the fungal yeast-to-filament transition. Phenazines impaired C. albicans growth on nonfermentable carbon sources and led to increased production of fer- mentation products (ethanol, glycerol, and acetate) in glucose-containing medium, leading us to propose that phenazines specif- ically inhibited respiration. Methylene blue, another inhibitor of respiration, also prevented the formation of structured colony biofilms. The inhibition of filamentation and colony wrinkling was not solely due to lowered extracellular pH induced by fer- mentation. Compared to smooth, unstructured colonies, wrinkled colony biofilms had higher oxygen concentrations within the colony, and wrinkled regions of these colonies had higher levels of respiration. Together, our data suggest that the structure of the fungal biofilm promotes access to oxygen and enhances respiratory metabolism and that the perturbation of respiration by bacterial molecules such as phenazines or compounds with similar activities disrupts these pathways. These findings may sug- gest new ways to limit fungal biofilms in the context of disease

Antifungal mechanisms by which a novel Pseudomonas aeruginosa phenazine toxin kills Candida albicans in biofilms

Pseudomonas aeruginosa produces several phenazines including the recently described 5-methyl-phenazine-1-carboxylic acid (5MPCA), which exhibits a novel antibiotic activity towards pathogenic fungi such as Candida albicans . Here we characterize the unique antifungal mechanisms of 5MPCA using its analogue phenazine methosulphate (PMS). Like 5MPCA, PMS induced fungal red pigmentation and killing. Mass spectrometry analyses demonstrated that PMS can be covalently modified by amino acids, a process that yields red derivatives. Furthermore, soluble proteins from C. albicans grown with either PMS or P. aeruginosa were also red and demonstrated absorbance and fluorescence spectra similar to that of PMS covalently linked to either amino acids or proteins in vitro , suggesting that 5MPCA modification by protein amine groups occurs in vivo . The red-pigmented C. albicans soluble proteins were reduced by NADH and spontaneously oxidized by oxygen, a reaction that likely generates reactive oxygen species (ROS). Additional evidence indicated that ROS generation precedes 5MPCA-induced fungal death. Reducing conditions greatly enhanced PMS uptake by C. albicans and killing. Since 5MPCA was more toxic than other phenazines that are not modified, such as pyocyanin, we propose that the covalent binding of 5MPCA promotes its accumulation in target cells and contributes to its antifungal activity in mixed-species biofilms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79382/1/j.1365-2958.2010.07414.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/79382/2/MMI_7414_sm_Figures_Table.pd

DEPTOR Expression Correlates with Muscle Protein Synthesis

Mammalian target of rapamycin (mTOR) has long been declared a focal point of muscle protein synthesis. mTORC1 (an mTOR complex consisting of mTOR, raptor, PRAS40, and mLST8) has been associated with regulation of protein translation in muscle, altering expression and activity levels of key downstream targets S6K1 and eIF-4E-BP1. mTORC1 has been shown to be affected by various stimuli, including nutritional status, growth factors, and mechanical loading. But in past incidents we have found disconnects in muscle protein synthesis and mTOR signaling, stimulating discussions that mTOR content and activation alone may not be able to fully account for muscle protein synthesis. Gaining popularity as a target for anti-cancer therapies, we became interested in DEPTOR, an endogenous inhibitor of mTORC1. Pharmacological inhibition of DEPTOR in cell culture and mouse studies has displayed increases of anabolic signaling in response to atrophic circumstances. We present two unique catabolic conditions in which we explore DEPTOR expression and muscle protein synthesis and demonstrate the first known data proposing that DEPTOR expression is not only influenced by physiological stimuli, including mechanical loading and insulin sensitivity, but that DEPTOR expression strongly correlates with 24-hr cumulative muscle protein synthesis rates. In one study, male Sprague Dawley rats were subjected to various conditions of musculoskeletal unloading, reloading, and overload, in which hindlimb unloading (HU) was utilized to mimic chronic disuse atrophy (28-d), followed by ambulatory reloading (56-d post HU) with and without the addition of resistance exercise prescribed to assist in recovery (3 sessions/wk for 7-wks; progressive increases in added resistance up to ~60% BW). DEPTOR expression was assessed via Immunoblotting. 24-hr cumulative muscle protein synthesis (FSR) was measured via stable isotope labeling and quantified by gas chromatogram/mass spectrometry. DEPTOR demonstrated a strong negative correlation with FSR in the gastrocnemius (r = - 0.93261; p \u3c0.01). In our second study, male obese Zucker rats were divided into their lean and obese phenotypes, as well as placed into sedentary and resistance exercised groups. DEPTOR and FSR were assessed as described above following operant conditioning and four progressive exercise sessions over 9-d. Gastrocnemius DEPTOR/FSR was again significant (r = - 0.75723; p\u3c0.01). Collectively, these results are the first to associate physiologic changes in DEPTOR expression with alterations of FSR, which may have important implications towards the design of therapeutic targets for the control of muscle mass or in evaluating muscle anabolism

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

We present observations of 10 type Ia supernovae (SNe Ia) between 0.16 < z < 0.62. With previous data from our High-Z Supernova Search Team, this expanded set of 16 high-redshift supernovae and 34 nearby supernovae are used to place constraints on the Hubble constant (H_0), the mass density (Omega_M), the cosmological constant (Omega_Lambda), the deceleration parameter (q_0), and the dynamical age of the Universe (t_0). The distances of the high-redshift SNe Ia are, on average, 10% to 15% farther than expected in a low mass density (Omega_M=0.2) Universe without a cosmological constant. Different light curve fitting methods, SN Ia subsamples, and prior constraints unanimously favor eternally expanding models with positive cosmological constant (i.e., Omega_Lambda > 0) and a current acceleration of the expansion (i.e., q_0 < 0). With no prior constraint on mass density other than Omega_M > 0, the spectroscopically confirmed SNe Ia are consistent with q_0 <0 at the 2.8 sigma and 3.9 sigma confidence levels, and with Omega_Lambda >0 at the 3.0 sigma and 4.0 sigma confidence levels, for two fitting methods respectively. Fixing a ``minimal'' mass density, Omega_M=0.2, results in the weakest detection, Omega_Lambda>0 at the 3.0 sigma confidence level. For a flat-Universe prior (Omega_M+Omega_Lambda=1), the spectroscopically confirmed SNe Ia require Omega_Lambda >0 at 7 sigma and 9 sigma level for the two fitting methods. A Universe closed by ordinary matter (i.e., Omega_M=1) is ruled out at the 7 sigma to 8 sigma level. We estimate the size of systematic errors, including evolution, extinction, sample selection bias, local flows, gravitational lensing, and sample contamination. Presently, none of these effects reconciles the data with Omega_Lambda=0 and q_0 > 0.Comment: 36 pages, 13 figures, 3 table files Accepted to the Astronomical Journa