On Physical Scales of Dark Matter Halos

It is common practice to describe formal size and mass scales of dark matter halos as spherical overdensities with respect to an evolving density threshold. Here, we critically investigate the evolutionary effects of several such commonly used definitions and compare them to the halo evolution within fixed physical scales as well as to the evolution of other intrinsic physical properties of dark matter halos. It is shown that, in general, the traditional way of characterizing sizes and masses of halos dramatically overpredicts the degree of evolution in the last 10 Gyr, especially for low-mass halos. This pseudo-evolution leads to the illusion of growth even though there are no major changes within fixed physical scales. Such formal size definitions also serve as proxies for the virialized region of a halo in the literature. In general, those spherical overdensity scales do not coincide with the virialized region. A physically more precise nomenclature would be to simply characterize them by their very definition instead of calling such formal size and mass definitions 'virial'. In general, we find a discrepancy between the evolution of the underlying physical structure of dark matter halos seen in cosmological structure formation simulations and pseudo-evolving formal virial quantities. We question the importance of the role of formal virial quantities currently ubiquitously used in descriptions, models and relations that involve properties of dark matter structures. Concepts and relations based on pseudo-evolving formal virial quantities do not properly reflect the actual evolution of dark matter halos and lead to an inaccurate picture of the physical evolution of our universe.Comment: 17 pages, 14 figures, 1 table, ApJ accepte

Dramatizers in Purik and how they-smack!-evolved

Proceedings of the Workshop B of the 17th Himalayan Languages Symposium (Kobe, 6th-9th, September, 2011

Central City Exploitation by Urban Sprawl? Evidence from Swiss Local Communities

This paper investigates spatial spillovers in local spending decisions between the center and the surrounding local communities by using panel data of the canton of Lucerne during the 1990s. Due to the geographical fragmentation with a major central city and some 100 small suburban local communities within a distance from 4 to 55 kilometers to the center this area represents a particularly useful database in order to test the relevance of spatial interactions in a small metropolitan area. The empirical evidence confirms strategic interactions among suburban governments and the central city only for public education, health and environmental spending. There are no spatial interactions with the central city for overall government spending.spatial spillovers, strategic interaction, central city exploitation

Revisiting The First Galaxies: The effects of Population III stars on their host galaxies

We revisit the formation and evolution of the first galaxies using new hydrodynamic cosmological simulations with the ART code. Our simulations feature a recently developed model for H2 formation and dissociation, and a star formation recipe that is based on molecular rather than atomic gas. Here, we develop and implement a recipe for the formation of metal-free Population III stars in galaxy-scale simulations that resolve primordial clouds with sufficiently high density. We base our recipe on the results of prior zoom-in simulations that resolved the protostellar collapse in pre-galactic objects. We find the epoch during which Pop III stars dominated the energy and metal budget of the first galaxies to be short-lived. Galaxies which host Pop III stars do not retain dynamical signatures of their thermal and radiative feedback for more than 10^8 yr after the lives of the stars end in pair-instability supernovae, even when we consider the maximum reasonable efficiency of the feedback. Though metals ejected by the supernovae can travel well beyond the virial radius of the host galaxy, they typically begin to fall back quickly, and do not enrich a large fraction of the intergalactic medium. Galaxies with total mass in excess of 3 x 10^6 Msun re-accrete most of their baryons and transition to metal-enriched Pop II star formation.Comment: 13 pages, 9 figures, published in Ap

Revisiting The First Galaxies: The epoch of Population III stars

We investigate the transition from primordial Population III (Pop III) star formation to normal Pop II star formation in the first galaxies using new cosmological hydrodynamic simulations. We find that while the first stars seed their host galaxies with metals, they cannot sustain significant outflows to enrich the intergalactic medium, even assuming a top-heavy initial mass function. This means that Pop III star formation could potentially continue until z~6 in different unenriched regions of the universe, before being ultimately shut off by cosmic reionization. Within an individual galaxy, the metal production and stellar feedback from Pop II stars overtake Pop III stars in 20-200 Myr, depending on galaxy mass.Comment: 9 pages, 7 figures, published in Ap

The Conception of Life in Synthetic Biology

The phrase ‘synthetic biology' is used to describe a set of different scientific and technological disciplines, which share the objective to design and produce new life forms. This essay addresses the following questions: What conception of life stands behind this ambitious objective? In what relation does this conception of life stand to that of traditional biology and biotechnology? And, could such a conception of life raise ethical concerns? Three different observations that provide useful indications for the conception of life in synthetic biology will be discussed in detail: 1. Synthetic biologists focus on different features of living organisms in order to design new life forms, 2. Synthetic biologists want to contribute to the understanding of life, and 3. Synthetic biologists want to modify life through a rational design, which implies the notions of utilising, minimising/optimising, varying and overcoming life. These observations indicate a tight connection between science and technology, a focus on selected aspects of life, a production-oriented approach to life, and a design-oriented understanding of life. It will be argued that through this conception of life synthetic biologists present life in a different light. This conception of life will be illustrated by the metaphor of a toolbox. According to the notion of life as a toolbox, the different features of living organisms are perceived as various rationally designed instruments that can be used for the production of the living organism itself or secondary products made by the organism. According to certain ethical positions this conception of life might raise ethical concerns related to the status of the organism, the motives of the scientists and the role of technology in our societ

Simultaneous imaging of a lacZ-marked tumor and microvasculature morphology in vivo by dual-wavelength photoacoustic microscopy

Photoacoustic molecular imaging, combined with the reporter-gene technique, can provide a valuable tool for cancer research. The expression of the lacZ reporter gene can be imaged using photoacoustic imaging following the injection of X-gal, a colorimetric assay for the lacZ-encoded enzyme β-galactosidase. Dual-wavelength photoacoustic microscopy was used to non-invasively image the detailed morphology of a lacZ-marked 9L gliosarcoma and its surrounding microvasculature simultaneously in vivo, with a superior resolution on the order of 10 μm. Tumor-feeding vessels were found, and the expression level of lacZ in tumor was estimated. With future development of new absorption-enhancing reporter-gene systems, we anticipate this strategy can lead to a better understanding of the role of tumor metabolism in cancer initiation, progression, and metastasis, and in its response to therapy

The Absorption and Elimination of Some Commonly Used Drugs,with Practical Deductions From a Knowledge of the Same.

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