On Reinforcement Learning, Nurturing, and the Evolution of Risk Neutral

Reinforcement learning depends on agents being learning individuals, and when agents rely on their instincts rather than gathering data and acting accordingly, the population tends to be less successful than a true RL population. ÒRiskinessÓ is the elementary metric for determining how willing to rely on learning an individual or a population is. With a high learning parameter, as we denote riskiness in this paper, agents find the safest option and seldom deviate from it, essentially using learning to become a non-learning individual. With a low learning rate, agents ignore recency entirely and seek out the highest reward, regardless of the risk. We attempt in this paper to evolve this Òrisk neutralityÓ in a population by adding a safe exploration nurturing period during which agents are free to explore without consequence. We discovered the environmental conditions necessary for our hypotheses to be mostly satisfied and found that nurturing enables agents to distinguish between two different risky options to evolve risk neutrality. Too long of a nurturing period causes the evolution to waver before settling on a path with essentially random results, while a short nurturing period causes a successful evolution of risk neutrality. The non-nurturing case evolves risk aversion by default as we expected from a reinforcement learning system, because agents are unable to distinguish between the good risk and bad risk, so they decide to avoid risks altogether.Noundergraduat

Syngenic Adipose-Derived Stem/Stromal Cells Delivered in Decellularized Adipose Tissue Scaffolds Enhance In Vivo Tissue Regeneration Through Host Cell Recruitment

Decellularized adipose tissue (DAT) represents a promising adipogenic bioscaffold for applications in soft tissue augmentation or reconstruction. With the goal of investigating the role of syngeneic donor adipose-derived stem/stromal cells (ASCs) and host myeloid cells during in vivo adipose tissue regeneration, transgenic reporter mouse strains were used to track these cell populations within ASC-seeded and unseeded DAT scaffolds. Donor ASCs were obtained from dsRed transgenic mice. These cells were shown to express characteristic cell surface markers, and multilineage differentiation capacity was confirmed. To facilitate cell tracking, DAT scaffolds were subcutaneously implanted into MacGreen mice in which myeloid cells express enhanced green fluorescent protein (EGFP). ASC-seeded DAT scaffolds augmented total cell recruitment as well as adipogenesis, and influenced EGFP+ myeloid cell infiltration kinetics within the implants. The donor dsRed+ ASCs were retained within the DAT scaffolds up to 8 weeks post-implantation, and did not contribute directly to the newly formed adipocytes

An Uncertain Position: Examining the Status of Teaching as a Profession

The purpose of this paper is to identify the characteristics of a full profession, to review how many and which characteristics cannot be ascribed to teaching, and how this situation has come to be. The affect of gender and social class on the perception of teaching as a profession is discussed. Although, teaching still has an ambiguous status as a profession, discussing it will allow people to continue to talk, think and write about this issue. Teaching will probably never be considered a full profession because it does not involve all the characteristics of a profession

Estimating the unbiased estimator θ for population genetic survey data

We consider a method of approximating Weir and Cockerham\u27s θ, an unbiased estimator of genetic population structure, using values readily available from published studies using biased estimators (Wright\u27s FST or Nei\u27s GST). The estimation algorithm is shown to be useful for both model populations and real-world avian populations. However, the correlation between Wright\u27s FST and Weir and Cockerham\u27s θ is strong when compared among 39 empirical avian datasets. Thus, the advantage of approximating an unbiased estimator is unclear considering the small actual effect of θ\u27s bias-removing power on empirical datasets

Enantioselective, Lewis base-catalyzed transformations: I. Polyene sulfenocyclization (preparative and mechanistic aspects) II. Sulfenofunctionalization of alkenyl boronates enabled by 1,2-boronate migration

This thesis covers two independent projects which are united under the umbrella of Lewis base catalysis. Following an overview of the key principles behind Lewis base catalysis and how it is used to enhance the electrophilicity of Lewis acids (Chapter 1), the bulk of this thesis will focus on the development of a catalytic, enantioselective sulfenocyclization of polyenes (Chapter 2). Sulfenyl group transfer from a highly reactive, cationic, Lewis acid-base adduct to an unactivated alkene generates a cyclic thiiranium ion, which serves as the initiating event for a highly stereoselective polyene cyclization that is terminated by arenes or phenols. This reaction was enabled by the identification of hexafluoroisopropyl alcohol (HFIP) as a superior solvent which dramatically improves site selectivity of thiiranium ion generation. A broad substrate scope is demonstrated, and the tricyclic products are isolated in good yield and enantioselectivity. Furthermore, a number of functional group interconversions (FGIs) of the resulting thioether moiety are demonstrated. This method is employed for the concise, enantioselective syntheses of the natural products (+)-ferruginol and (+)-hinokiol. Additionally, investigations into the sulfenocyclization of trienes to form even more complex products are disclosed. Preliminary mechanistic experiments to elucidate the rate-determining step of the catalytic cycle and the order in each reaction component were also performed. Chapter 3 of this thesis will cover the development of a Lewis base-catalyzed, enantioselective carbosulfenylation of alkenylboronate complexes which is enabled by a 1,2-boronate migration. The generation of “iranium” ions from alkenylboronates triggers a diastereospecific, ring-opening migration of an alkyl or aryl group to form 1,2-difunctionalized organoboron compounds. This strategy was employed together with Lewis base-catalyzed, enantioselective sulfenyl group transfer to ultimately afford chiral, non-racemic alkylboronic esters in generally high yield, high enantioselectivity, and perfect diastereospecificity. The products of the transformation are useful synthetic intermediates, and a number of useful FGIs are demonstrated

Evaluation of a Hot Print System for the development of latent fingermarks on thermal paper:a pseudo-operational trial

Enhancement of latent fingermarks on thermal paper poses a number of problems when using traditional methods used for porous substrates due to blackening of the thermal layer as a result of polar solvents present within the reagents and high temperatures oxidising the acid/dye complex. Thus, methods which prevent such reactions are favoured for the development of latent prints on said substrates. A comparative pseudo-operational trial using UV, Hot Print System (HPS), ninhydrin and ThermaNIN was performed on 1000 thermal paper substrates gathered from various sources. The results indicated that the most effective method was an acetone pre-wash followed by ninhydrin. The sequence of HPS-ninhydrin was similarly effective when compared to ninhydrin as a sole technique. ThermaNIN produced fewer marks than ninhydrin but was superior to HPS. Whilst the HPS developed some fingermarks, there was only a very small number of marks uniquely developed by it.</p

A Potential Foundation for Emergent Space-Time

We present a novel derivation of both the Minkowski metric and Lorentz transformations from the consistent quantification of a causally ordered set of events with respect to an embedded observer. Unlike past derivations, which have relied on assumptions such as the existence of a 4-dimensional manifold, symmetries of space-time, or the constant speed of light, we demonstrate that these now familiar mathematics can be derived as the unique means to consistently quantify a network of events. This suggests that space-time need not be physical, but instead the mathematics of space and time emerges as the unique way in which an observer can consistently quantify events and their relationships to one another. The result is a potential foundation for emergent space-time.Comment: The paper was originally titled "The Physics of Events: A Potential Foundation for Emergent Space-Time". We changed the title (and abstract) to be more direct when the paper was accepted for publication at the Journal of Mathematical Physics. 24 pages, 15 figure

Pannexin 1 regulates adipose stromal cell differentiation and fat accumulation

Pannexin 1 (Panx1) is a channel-forming glycoprotein important in paracrine signaling and cellular development. In this study, we discovered that mice globally lacking Panx1 (KO) have significantly greater total fat mass and reduced lean mass compared to wild type (WT) mice under a normal diet. Despite having higher fat content, Panx1 KO mice on a high fat diet exhibited no differences in weight gain and blood markers of obesity as compared to WT controls, except for an increase in glucose and insulin levels. However, metabolic cage data revealed that these Panx1 KO mice display significantly increased activity levels, higher ambulatory activity, and reduced sleep duration relative to their WT littermates on a high-fat diet. To uncover the cellular mechanism responsible for the increased fat content in the KO, we isolated primary cultures of adipose-derived stromal cells (ASCs) from WT and KO fat pads. In WT ASCs we observed that Panx1 protein levels increase upon induction into an adipogenic lineage. ASCs isolated from Panx1 KO mice proliferate less but demonstrate enhanced adipogenic differentiation with increased intracellular lipid accumulation, glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, and adipokine secretion, as compared to WT ASCs. This was consistent with the increased adipocyte size and decreased adipocyte numbers observed in subcutaneous fat of the Panx1 KO mice compared to WT. We concluded that Panx1 plays a key role in adipose stromal cells during the early stages of adipogenic proliferation and differentiation, regulating fat accumulation in vivo