Population and environmental quality

Cronshaw MB, Requate T. Population and environmental quality. Working Papers. Institute of Mathematical Economics. Vol 223. Bielefeld: Center for Mathematical Economics; 1994.This paper considers first best allocations in an economy where a consumption good is produced using labor. Production results in pollution, which is a public bad. Pollution abatement can be achiedved either by restricting poduction output or by using labor. We consider how the first best allocation varies with polulation size. consumers are unambiguously worse off when the population is larger. However, surprisingly, there is no single optimal policy on how pollution and labor should vary with population size. For standard models of preferences and technology it might be desirable either to increase or to reduce emissions and/or labor, depending on parameters. Despite such ambiguity in the first best level of emissions, the Pigouvian tax wihich implements the first best is a non-decreasing function of the population size. We conclude that, since the comparative statics of the first best are so ambiguous, sensible debate on environmental policy cannot proceed without a careful determination of actual preferences and technology

Assessing the viability of laser-activated dental bleaching compared to conventional in-office bleaching methods: A systematic review of clinical and in vitro studies.

open access articleLaser-activated tooth bleaching is discussed as a means to optimize results, while minimizing adverse side effects, but it lacks consensus in the scientific literature. Therefore, this systematic review aims to evaluate the protocols and outcomes of laser-activated vs. non-activated bleaching methods for safe and effective approaches. The PubMed, Cochrane, Scopus, ScienceDirect, and Google Scholar search engines, with the following MeSH terms and keywords: (bleaching OR whitening) AND laser AND (tooth OR dental OR enamel OR dentine), were used to identify human clinical trials and in vitro studies regarding laser-activated dental bleaching. After applying the keywords and additional filters, and inclusion and exclusion criteria, the final number of included articles was 19 clinical and 20 in vitro studies. Laser activation yielded no significant color improvement, but reduced gel contact time (10 min). Laser-activated bleaching required 24% less hydrogen peroxide (HP) concentration to achieve similar results. Additionally, there were no significant differences in terms of sensitivity and hard tissue alterations between the laser-activated and conventional groups. The benefits associated with laser-activated bleaching render it a compelling option. Nevertheless, a comprehensive evaluation of bleaching gels and activation protocols is imperative. Ultimately, this analysis provides clinical guidance pertaining to the facilitatory employment of laser irradiation

Current Concepts of Laser–Oral Tissue Interaction.

open access articleFundamental to the adjunctive use of laser photonic energy for delivering therapy and tissue management, is the ability of the incident energy to be absorbed by target tissues. The aim of this review is to examine the differential performance of the separate components of oral hard and soft tissues when exposed to laser photonic irradiance of variable wavelengths and power values. Through an examination of peer-reviewed published data and materials, the interaction of laser photonic energy and target tissues are explored in detail. Varying laser wavelength emissions relative to anatomical structures explores the ability to optimise laser–tissue interactions, and also identifies possible risk scenarios as they apply to adjacent non-target structures. The concepts and practical aspects of laser photonic energy interactions with target oral tissues are clearly demonstrated. Emphasis was placed on optimising the minimum level of laser power delivery in order to achieve a desired tissue effect, whilst minimising the risk or outcome of collateral tissue damage

Formation of the postmitotic nuclear envelope from extended ER cisternae precedes nuclear pore assembly

During mitosis, the nuclear envelope merges with the endoplasmic reticulum (ER), and nuclear pore complexes are disassembled. In a current model for reassembly after mitosis, the nuclear envelope forms by a reshaping of ER tubules. For the assembly of pores, two major models have been proposed. In the insertion model, nuclear pore complexes are embedded in the nuclear envelope after their formation. In the prepore model, nucleoporins assemble on the chromatin as an intermediate nuclear pore complex before nuclear envelope formation. Using live-cell imaging and electron microscope tomography, we find that the mitotic assembly of the nuclear envelope primarily originates from ER cisternae. Moreover, the nuclear pore complexes assemble only on the already formed nuclear envelope. Indeed, all the chromatin-associated Nup 107–160 complexes are in single units instead of assembled prepores. We therefore propose that the postmitotic nuclear envelope assembles directly from ER cisternae followed by membrane-dependent insertion of nuclear pore complexes

Evolution of the nucleus

Under a Creative Commons license.The nucleus represents a major evolutionary transition. As a consequence of separating translation from transcription many new functions arose, which likely contributed to the remarkable success of eukaryotic cells. Here we will consider what has recently emerged on the evolutionary histories of several key aspects of nuclear biology; the nuclear pore complex, the lamina, centrosomes and evidence for prokaryotic origins of relevant players.Work in our laboratories was supported by the following agencies, and which is gratefully acknowledged; MRC and Wellcome Trust (MR/K008749/1 and 090007/Z/09/Z respectively, to MCF), C2A Junta de Andalucia to DPD and DFG GR1642/4-1 to RG.Open Access funded by Wellcome Trust.Peer Reviewe

International Perspectives on the Legal Environment for Selection

Perspectives from 22 countries on aspects of the legal environment for selection are presented in this article. Issues addressed include (a) whether there are racial/ethnic/religious subgroups viewed as "disadvantaged,” (b) whether research documents mean differences between groups on individual difference measures relevant to job performance, (c) whether there are laws prohibiting discrimination against specific groups, (d) the evidence required to make and refute a claim of discrimination, (e) the consequences of violation of the laws, (f) whether particular selection methods are limited or banned, (g) whether preferential treatment of members of disadvantaged groups is permitted, and (h) whether the practice of industrial and organizational psychology has been affected by the legal environmen

Involvement in surface antigen expression by a moonlighting FG-repeat nucleoporin in trypanosomes

Components of the nuclear periphery coordinate a multitude of activities, including macromolecular transport, cell-cycle progression, and chromatin organization. Nuclear pore complexes (NPCs) mediate nucleocytoplasmic transport, mRNA processing, and transcriptional regulation, and NPC components can define regions of high transcriptional activity in some organisms at the nuclear periphery and nucleoplasm. Lineage-specific features underpin several core nuclear functions and in trypanosomatids, which branched very early from other eukaryotes, unique protein components constitute the lamina, kinetochores, and parts of the NPCs. Here we describe a phenylalanine-glycine (FG)-repeat nucleoporin, TbNup53b, that has dual localizations within the nucleoplasm and NPC. In addition to association with nucleoporins, TbNup53b interacts with a known trans-splicing component, TSR1, and has a role in controlling expression of surface proteins including the nucleolar periphery-located, procyclin genes. Significantly, while several nucleoporins are implicated in intranuclear transcriptional regulation in metazoa, TbNup53b appears orthologous to components of the yeast/human Nup49/Nup58 complex, for which no transcriptional functions are known. These data suggest that FG-Nups are frequently co-opted to transcriptional functions during evolution and extend the presence of FG-repeat nucleoporin control of gene expression to trypanosomes, suggesting that this is a widespread and ancient eukaryotic feature, as well as underscoring once more flexibility within nucleoporin function

Plays in Frontier Areas – An

Increasing global energy demands make the exploration for coalbed methane (CBM) plays in frontier areas attractive. CBM can be used as a feedstock to generate power and manufacture alternative products such as diesel (gas-to-liquids), liquid natural gas, and fertilizer. Challenges to economic development of CBM resources in remote areas of the world include undeveloped markets, distance to markets, and lack of infrastructure. The four stages in the evaluation of a CBM project follow: 1. Formulate a strategic plan to define the objectives and duration of the project. 2. Conduct a feasibility study to analyze the economic and market potential of the project and determine appropriate production methods. 3. Initiate an exploratory drilling program to identify contingent resources and “sweet spots ” for pilot wells. 4. Prepare a reserve estimate report based on production from the pilot wells to obtain financing for project development. The relatively unexplored Kalahari Basin in southern Africa has all of the prerequisites for a giant CBM play. Permo-Triassic (Gondwana) coal-bearing strata of the Karoo Supergroup underlie 60 percent of Botswana. Coal and organic-rich shale intervals are as much as 100 meters thick at depths between 300 and 1000 meters. Impermeable massive calcareous mudstone seals overlie the coalbearing rocks throughout the basin. Estimated gas-in-place in the central part of the basin is as much as 196 TCF. These condition

Lasers in orthodontics

Lasers are relatively new additions to orthodontic therapy. This paper reviews the available laser wavelengths and will discuss some adjunct application of diode lasers for soft tissue procedures. These include photobiomodulation, laser gingivectomy to improve oral hygiene or bracket positioning, aesthetic laser gingival recontouring and laser exposure of the superficially impacted teeth. Selected treated cases will be presented throughout