Variational Principles for Natural Divergence-free Tensors in Metric Field Theories

Let $T^{ab}=T^{ba}=0$ be a system of differential equations for the components of a metric tensor on $R^m$. Suppose that $T^{ab}$ transforms tensorially under the action of the diffeomorphism group on metrics and that the covariant divergence of $T^{ab}$ vanishes. We then prove that $T^{ab}$ is the Euler-Lagrange expression some Lagrangian density provided that $T^{ab}$ is of third order. Our result extends the classical works of Cartan, Weyl, Vermeil, Lovelock, and Takens on identifying field equations for the metric tensor with the symmetries and conservation laws of the Einstein equations

Some thoughts on GAIA and the sulfur cycle

The data hypothesis states that the composition, oxidation reduction state, and temperature of the troposphere are actively regulated by the biota for the biota. One of the early predictions of the Gaia hypothesis was that there should be a sulfur compound made by the biota in the oceans. It would need to be stable enough against oxidation in water to allow its transfer to the air. Either the sulfur compound itself or its atmospheric oxidation product would have to return sulfur from the sea to the land surfaces. The most likely candidate for this role was dimethyl sulfide. Another sulfur compound of interest from a Gaian viewpoint CS2 (carbon disulfide) is discussed. Theories on the production of dimethyl sulfide and carbon disulfide related to the Gaian hypothesis are examined

Evaluation of Effectiveness of Marketing Communication Mix Elements in Nigerian Service Sector

Creating effective communication with customers is the most important aspect in services marketing. To date we still have poor understanding of the role of effective marketing communication with customers in attracting and maintaining prospective and present customers. This research study assess the effectiveness of advertising and personal selling practices of Nigerian service sector in communicating with its customers with the aim of finding solutions to improve the existing communication and customer satisfaction. After reviewing related literature, a questionnaire was prepared and distributed to 200 customers, out of which 25% from the telecommmrications and 15% each from the remaining seven service industries viz banking and insurance, education, travel, tourism, hotel industry and hospital industry used to gather the data about the effectiveness of advertising and personal selling activities. The participants were selected randomly once the service type is determined by stratified sampling. The data collected was analyzed based on predetermined rating factors and expected results of performance with SPSS software package. In conclusion the findings of the analysis showed that Nigerian service sectors advertising and personal selling indicated moderately effective in providing information, creating awareness, changing attitude, ineffective in building company image and enforcing brand loyalty. The research also identified lack of integration between advertising and personal selling

Martian atmospheric compositional analysis- its biological significance first quarterly progress report, 15 may - 15 aug. 1965

Biological significance of Martian atmospheric compositional analysis, and life detection studies of chemical free energy in surface matte

Galactic Potentials

The information contained in galactic rotation curves is examined under a minimal set of assumptions. If emission occurs from stable circular geodesic orbits of a static spherically symmetric field, with information propagated to us along null geodesics, observed rotation curves determine galactic potentials without specific reference to any metric theory of gravity. Given the potential, the gravitational mass can be obtained by way of an anisotropy function of this field. The gravitational mass and anisotropy function can be solved for simultaneously in a Newtonian limit without specifying any specific source. This procedure, based on a minimal set of assumptions, puts very strong constraints on any model of the "dark matter".Comment: A somewhat longer form of the final version to appear in Physical Review Letters.Clarification and further reference

Daisyworld: a review

Daisyworld is a simple planetary model designed to show the long-term effects of coupling between life and its environment. Its original form was introduced by James Lovelock as a defense against criticism that his Gaia theory of the Earth as a self-regulating homeostatic system requires teleological control rather than being an emergent property. The central premise, that living organisms can have major effects on the climate system, is no longer controversial. The Daisyworld model has attracted considerable interest from the scientific community and has now established itself as a model independent of, but still related to, the Gaia theory. Used widely as both a teaching tool and as a basis for more complex studies of feedback systems, it has also become an important paradigm for the understanding of the role of biotic components when modeling the Earth system. This paper collects the accumulated knowledge from the study of Daisyworld and provides the reader with a concise account of its important properties. We emphasize the increasing amount of exact analytic work on Daisyworld and are able to bring together and summarize these results from different systems for the first time. We conclude by suggesting what a more general model of life-environment interaction should be based on

Bottom Quark Mass Determination from low-n Sum Rules

We study the uncertainties in the MSbar bottom quark mass determination using relativistic sum rules to O(alpha_S^2). We include charm mass effects and secondary b bbar production and treat the experimental continuum region more conservatively than previous analyses. The PDG treatment of the region between the resonances Upsilon (4S) and Upsilon (5S) is reconsidered. Our final result reads: m_b(m_b)=(4.20 \pm 0.09) GeV.Comment: 4 pages, Talk given at QCD 03, Montpellier, France, 2-9 July 200

Spectral Evolution of an Earth-Like Planet

We have developed a characterization of the geological evolution of the Earths atmosphere and surface in order to model the observable spectra of an Earth-like planet through its geological history. These calculations are designed to guide the interpretation of an observed spectrum of such a planet by future instruments that will characterize exoplanets. Our models focus on spectral features that either imply habitability or are required for habitability. These features are generated by H2O, CO2, CH4, O2, O3, N2O, and vegetation-like surface albedos. We chose six geological epochs to characterize. These epochs exhibit a wide range in abundance for these molecules, ranging from a CO2 rich early atmosphere, to a CO2/CH4-rich atmosphere around 2 billion years ago to a present-day atmosphere. We analyzed the spectra to quantify the strength of each important spectral feature in both the visible and thermal infrared spectral regions, and the resolutions required to unambiguously observe the features for each epoch. We find a wide range of spectral resolutions required for observing the different features. For example, H2O and O3 can be observed with relatively low resolution, while O2 and N2O require higher resolution. We also find that the inclusion of clouds in our models significantly affects both the strengths and resolutions required to observe all spectral features.Comment: 34 pages, 24 fig, pdf, ApJ, TB

On the naturalness of Einstein's equation

We compute all 2-covariant tensors naturally constructed from a semiriemannian metric which are divergence-free and have weight greater than -2. As a consequence, it follows a characterization of the Einstein tensor as the only, up to a constant factor, 2-covariant tensor naturally constructed from a semiriemannian metric which is divergence-free and has weight 0 (i.e., is independent of the unit of scale). Since these two conditions are also satisfied by the energy-momentum tensor of a relativistic space-time, we discuss in detail how these theorems lead to the field equation of General Relativity.Comment: 12 pages, added references, corrected typo