Reproductive decisions by black brant: mechanisms to synchronize hatch and spatial variation in growth rates of goslings

Thesis (M.S.) University of Alaska Fairbanks, 2003I investigated two aspects of reproductive decisions in Black Brant: synchronous hatch within clutches and areas in which to rear their broods. It has been hypothesized that Anatidae facilitate a synchronous hatch through vocalizations among embryos within the same clutch. I performed manipulative experiments in which variation was controlled for both genetic and incubation pattern sources in incubation period length. Our results suggest that vocalizations are not responsible for a synchronous hatch, and I suggest that inherent properties of the eggs themselves are responsible for a synchronous hatch. Additionally, I compared gosling growth rates from areas of low nest densities with those from a main colony to test the hypothesis that broods using dispersed areas were escaping density dependent effects. I found that goslings from dispersed nesting areas did not escape density dependent effects and may actually constitute a sink for the population from additional effects of increased nest mortality in dispersed nesting area.Ch. 1. Regulation of development time and hatch synchronization ihn black brant (Branta bernicla nigricans) -- ch. 2. Do black brant goslings from satellite colonies on the Yukon-Kuskokwim Delta, Alaska experience reduced density dependence? -- Summary

The Struggle to Distinguish Transcendental Phenomenology and Psychology

Dieser Beitrag widmet sich Husserls Differenzierungsversuch von transzendentaler Phänomenologie und eidetischer Psychologie. Die These lautet: Die Unterscheidung blieb problematisch, sodass Husserls Analysen oftmals zwar wertvolle, aber als Erkenntnistheorie missverstandene Beiträge zur Psychologie sind. Es wird aufgezeigt, inwiefern die Verwechslung von erkenntnistheoretischen und psychologischen Untersuchungen die Gefahr eines Psychologismus birgt. Der Beitrag zeigt, wie die Bewusstwerdung des Bewusstseins zu einer Art Reduplikation der Welt führt und warum dies Husserl veranlasste, der Psychologie einen auch epistemologischen Vorrang einzuräumen. Dagegen werden Überlegungen angestellt, wo und wie das Anliegen der Erkenntnistheorie und psychologische Untersuchungen zur Bewusstseinsgenese methodologisch zu separieren sind. Abschließend wird erwogen, wie Husserls eigentlich psychologische Beiträge für das Anliegen einer phänomenologischen Psychologie fruchtbar zu machen sind.This article addresses Husserl’s attempt to differentiate between transcendental phenomenology and eidetic psychology. The thesis is: The distinction remained problematic so that Husserl’s analyses are often valuable contributions to psychology that, however, are mistaken to be epistemology. It is shown how and why the confusion of epistemological and psychological investigations harbors the danger of a psychologism. The article shows how becoming conscious of consciousness leads to a kind of reduplication of the world and why this led Husserl to give psychology an epistemological priority. On the other hand, it considers where and how the concern of epistemology and psychological investigations on the genesis of consciousness can be methodologically separated. Finally, it offers perspectives on how Husserl’s psychological contributions can be made fruitful for the project of a phenomenological psychology

The New Economics of Equilibrium Sorting and its Transformational Role for Policy Evaluation

Households “sort” across neighborhoods according to their wealth and their preferences for public goods, social characteristics, and commuting opportunities. The aggregation of these individual choices in markets and in other institutions influences the supply of amenities and local public goods. Pollution, congestion, and the quality of public education are examples. Over the past decade, advances in economic models of this sorting process have led to new framework that promises to alter the ways we conceptualize the policy evaluation process in the future. These “equilibrium sorting” models use the properties of market equilibria, together with information on household behavior, to infer structural parameters that characterize preference heterogeneity. The results can be used to develop theoretically consistent predictions for the welfare implications of future policy changes. Analysis is not confined to marginal effects or a partial equilibrium setting. Nor is it limited to prices and quantities. Sorting models can integrate descriptions of how non-market goods are generated, estimate how they affect decision making and, in turn, predict how they will be affected by future policies targeting prices or quantities. Conversely, sorting models can predict how equilibrium prices and quantities will be affected by policies which target product quality, information, or amenities generated by the sorting process. These capabilities are just beginning to be understood and used in applied research. This survey article aims to synthesize the state of knowledge on equilibrium sorting, the new possibilities for policy analysis, and the conceptual and empirical challenges that define the frontiers of the literature.

Adaptations to hydrothermal vent life in Kiwa tyleri, a new species of yeti crab from the East Scotia Ridge, Antarctica

Hydrothermal vents in the Southern Ocean are the physiologically most isolated chemosynthetic environments known. Here, we describe Kiwa tyleri sp. nov., the first species of yeti crab known from the Southern Ocean. Kiwa tyleri belongs to the family Kiwaidae and is the visually dominant macrofauna of two known vent sites situated on the northern and southern segments of the East Scotia Ridge (ESR). The species is known to depend on primary productivity by chemosynthetic bacteria and resides at the warm-eurythermal vent environment for most of its life; its short-range distribution away from vents (few metres) is physiologically constrained by the stable, cold waters of the surrounding Southern Ocean. Kiwa tylerihas been shown to present differential life history adaptations in response to this contrasting thermal environment. Morphological adaptations specific to life in warm-eurythermal waters, as found on – or in close proximity of – vent chimneys, are discussed in comparison with adaptations seen in the other two known members of the family (K. hirsuta, K. puravida), which show a preference for low temperature chemosynthetic environments

Unsupervised Idealization of Ion Channel Recordings by Minimum Description Length:Application to Human PIEZO1-Channels

Researchers can investigate the mechanistic and molecular basis of many physiological phenomena in cells by analyzing the fundamental properties of single ion channels. These analyses entail recording single channel currents and measuring current amplitudes and transition rates between conductance states. Since most electrophysiological recordings contain noise, the data analysis can proceed by idealizing the recordings to isolate the true currents from the noise. This de-noising can be accomplished with threshold crossing algorithms and Hidden Markov Models, but such procedures generally depend on inputs and supervision by the user, thus requiring some prior knowledge of underlying processes. Channels with unknown gating and/or functional sub-states and the presence in the recording of currents from uncorrelated background channels present substantial challenges to such analyses. Here we describe and characterize an idealization algorithm based on Rissanen's Minimum Description Length (MDL) Principle. This method uses minimal assumptions and idealizes ion channel recordings without requiring a detailed user input or a priori assumptions about channel conductance and kinetics. Furthermore, we demonstrate that correlation analysis of conductance steps can resolve properties of single ion channels in recordings contaminated by signals from multiple channels. We first validated our methods on simulated data defined with a range of different signal-to-noise levels, and then showed that our algorithm can recover channel currents and their substates from recordings with multiple channels, even under conditions of high noise. We then tested the MDL algorithm on real experimental data from human PIEZO1 channels and found that our method revealed the presence of substates with alternate conductances

Heterobimetallic Eu(III)/Pt(II) single-chain nanoparticles: a path to enlighten catalytic reactions

We introduce the formation and characterization of heterometallic single-chain nanoparticles entailing both catalytic and luminescent properties. A terpolymer containing two divergent ligand moieties, phosphines and phosphine oxides, is synthesized and intramolecularly folded into nanoparticles via a selective metal complexation of Pt(II) and Eu(III). The formation of heterometallic Eu(III)/Pt(II) nanoparticles is evidenced by size exclusion chromatography, multinuclear NMR ($^{1}$H, $^{31}$P{$^{1}$H}, $^{19}$F, $^{195}$Pt) as well as diffusion-ordered NMR and IR spectroscopy. Critically, we demonstrate the activity of the SCNPs as a homogeneous and luminescent catalytic system in the amination reaction of allyl alcohol

Role of structural dynamics in selectivity and mechanism of non-heme Fe(II) and 2-Oxoglutarate-dependent Oxygenases involved in DNA repair

AlkB and its human homologue AlkBH2 are Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenases that repair alkylated DNA bases occurring as a consequence of reactions with mutagenic agents. We used molecular dynamics (MD) and combined quantum mechanics/molecular mechanics (QM/MM) methods to investigate how structural dynamics influences the selectivity and mechanisms of the AlkB- and AlkBH2-catalyzed demethylation of 3-methylcytosine (m3C) in single (ssDNA) and double (dsDNA) stranded DNA. Dynamics studies reveal the importance of the flexibility in both the protein and DNA components in determining the preferences of AlkB for ssDNA and of AlkBH2 for dsDNA. Correlated motions, including of a hydrophobic β-hairpin, are involved in substrate binding in AlkBH2–dsDNA. The calculations reveal that 2OG rearrangement prior to binding of dioxygen to the active site Fe is preferred over a ferryl rearrangement to form a catalytically productive Fe(IV)═O intermediate. Hydrogen atom transfer proceeds via a σ-channel in AlkBH2–dsDNA and AlkB–dsDNA; in AlkB–ssDNA, there is a competition between σ- and π-channels, implying that the nature of the complexed DNA has potential to alter molecular orbital interactions during the substrate oxidation. Our results reveal the importance of the overall protein–DNA complex in determining selectivity and how the nature of the substrate impacts the mechanism