Capital Gains and the Economic Theory of Corporate Finance

The dependence of one agent’s actions upon those of another constitutes a fundamental departure point for much of received economic theory. Apart from a deterministic setting, the presence of uncertainty implies a dependence on the probable actions of other agents; that is, the ultimate behavior of an individual is to a certain extent a consequence of his beliefs concerning the behavior of other agents. While the difficulty associated with formulating even crude conjectures of this nature is overwhelming, actual informational demands are even greater as from the dependence of agent A’s actions on his beliefs concerning agent B’s actions, it follows directly that agent B’s actions are dependent on his beliefs concerning agent A’s beliefs relative to his (agent B’s) action as well, as infinitum

Water Law, Water Transfers, and Economic Efficiency: The Colorado River

[No abstract

Mapping functional traits: comparing abundance and presence-absence estimates at large spatial scales

Efforts to quantify the composition of biological communities increasingly focus on functional traits. The composition of communities in terms of traits can be summarized in several ways. Ecologists are beginning to map the geographic distribution of trait-based metrics from various sources of data, but the maps have not been tested against independent data. Using data for birds of the Western Hemisphere, we test for the first time the most commonly used method for mapping community trait composition – overlaying range maps, which assumes that the local abundance of a given species is unrelated to the traits in question – and three new methods that as well as the range maps include varying degrees of information about interspecific and geographic variation in abundance. For each method, and for four traits (body mass, generation length, migratory behaviour, diet) we calculated community-weighted mean of trait values, functional richness and functional divergence. The maps based on species ranges and limited abundance data were compared with independent data on community species composition from the American Christmas Bird Count (CBC) scheme coupled with data on traits. The correspondence with observed community composition at the CBC sites was mostly positive (62/73 correlations) but varied widely depending on the metric of community composition and method used (R2: 5.6×10−7 to 0.82, with a median of 0.12). Importantly, the commonly-used range-overlap method resulted in the best fit (21/22 correlations positive; R2: 0.004 to 0.8, with a median of 0.33). Given the paucity of data on the local abundance of species, overlaying range maps appears to be the best available method for estimating patterns of community composition, but the poor fit for some metrics suggests that local abundance data are urgently needed to allow more accurate estimates of the composition of communities

Concave Switching in Single and Multihop Networks

Switched queueing networks model wireless networks, input queued switches and numerous other networked communications systems. For single-hop networks, we consider a {($\alpha,g$)-switch policy} which combines the MaxWeight policies with bandwidth sharing networks -- a further well studied model of Internet congestion. We prove the maximum stability property for this class of randomized policies. Thus these policies have the same first order behavior as the MaxWeight policies. However, for multihop networks some of these generalized polices address a number of critical weakness of the MaxWeight/BackPressure policies. For multihop networks with fixed routing, we consider the Proportional Scheduler (or (1,log)-policy). In this setting, the BackPressure policy is maximum stable, but must maintain a queue for every route-destination, which typically grows rapidly with a network's size. However, this proportionally fair policy only needs to maintain a queue for each outgoing link, which is typically bounded in number. As is common with Internet routing, by maintaining per-link queueing each node only needs to know the next hop for each packet and not its entire route. Further, in contrast to BackPressure, the Proportional Scheduler does not compare downstream queue lengths to determine weights, only local link information is required. This leads to greater potential for decomposed implementations of the policy. Through a reduction argument and an entropy argument, we demonstrate that, whilst maintaining substantially less queueing overhead, the Proportional Scheduler achieves maximum throughput stability.Comment: 28 page

Methods of isolation and identification of pathogenic and potential pathogenic bacteria from skins and tannery effluents

Currently there is no standard protocol available within the leather industry to isolate and identify pathogenic bacteria from hides, skins or tannery effluent. This study was therefore carried out to identify simple but effective methods for isolation and identification of bacterial pathogens from the effluent and skins during leather processing. Identification methods based on both phenotypic and genotypic characteristics were investigated. Bacillus cereus and Pseudomonas aeruginosa were used as indicator bacteria to evaluate the isolation and identification methods. Decontaminated calfskins were inoculated with a pure culture of the above mentioned bacterial species followed by a pre-tanning and chromium tanning processes. Effluent samples were collected and skins were swabbed at the end of each processing stage. Bacterial identification was carried out based on the phenotypic characteristics; such as colony appearance on selective solid media, cell morphology following a standard Gram-staining and spore staining techniques, and biochemical reactions, e.g., the ability of a bacterial species to ferment particular sugars and ability to produce certain enzymes. Additionally, an identification system based on bacterial phenotypic characteristics, known as Biolog® system was applied. A pulsed-filed gel electrophoresis (PFGE) method for bacterial DNA fingerprinting was also evaluated and used for the identification of the inoculated bacteria. The methods described in the study were found to be effective for the identification of pathogenic bacteria from skins and effluent

The Ultrastructure of Cryo-Sections and Intact Vitrified Cells - The Effects of Cryoprotectants and Acceleration Voltage on Beam Induced Bubbling

Chemically fixed pancreas was infiltrated with various cryoprotectants to obtain homogeneously vitrified samples upon cooling. The suitability of these samples for cryo-ultramicrotomy was tested. Contrast was hardly detectable initially in thin cryo-sections but increased upon irradiation, irrespective of the cryoprotectant (glycerol, propylene glycol, methanol) used. Contrast and beam damage were analyzed in vitrified thin films from collagen, phospholipid vesicles and various concentrations of glycerol. Glycerol increased the beam sensitivity of both collagen and phospholipid vesicles, but diminished the contrast between matrix and lipid vesicles or collagen fibers. The effects of glycerol as observed in thin films explain some of the effects of cryoprotectants in thin cryo-sections. To reduce beam damage in vitrified specimens two approaches are proposed. Firstly, when vitrified films are prepared, dilute suspensions should be used without cryoprotectant. In some cases, such as (thin) intact cells, the composition of the suspended material can only be marginally influenced. Then a second approach can be used involving the application of higher accelerating voltages (e.g. 300 kV). This has two advantages; the increase in mean free path-length of the electrons causes less beam damage on one hand and allows better resolution of thick specimens on the other hand. Micrographs from E. coli bacteria vitrified from suspension illustrate some of the potentials of intermediate voltage cryo-electron microscopy