Gravitational Radiation: Maxwell-Heaviside Formulation

To fully describe gravitational energy flux by using an analog to the Maxwell-Heaviside equations for electrodynamics, the Liénard–Wiechert potentials and fields are derived for gravitation along with radiation patterns and corresponding Larmor formulas for total radiated power. Due to attraction of like gravitational charges (masses) as opposed to repulsion of like electrical charges, the mass-density and current-density terms pick up a negative sign along with a factor of the universal gravitational constant, G. This results in a sign change of the Poynting vector, indicating energy is gained by the field as opposed to energy being lost by the field, such is the case for electromagnetic radiation. The gravitational and cogravitational fields, analogous to the electric and magnetic fields, respectively, behave as described by Heaviside and Lorentz. Like an electric charge, a gravitic charge (mass) in uniform motion is found to produce a spherical field which contracts along the axis of motion as its velocity approaches the limiting speed of propagation. The speed of gravitational propagation is assumed to be equivalent to that of light, though this may not necessarily be the case. For an accelerated mass, the resulting gravitational radiation mirrors the dipole pattern produced by an accelerated electric charge, similarly oriented about the axis of acceleration yet contracting in the reverse direction at relativistic speeds. These results seek to further inquire on the nature of gravitational fields

Missouri mail-in record farms 1964 to 1973 : investments, productions, costs and returns

Cover title

Using graphical and pictorial representations to teach introductory astronomy students about the detection of extrasolar planets via gravitational microlensing

The detection and study of extrasolar planets is an exciting and thriving field in modern astrophysics, and an increasingly popular topic in introductory astronomy courses. One detection method relies on searching for stars whose light has been gravitationally microlensed by an extrasolar planet. In order to facilitate instructors' abilities to bring this interesting mix of general relativity and extrasolar planet detection into the introductory astronomy classroom, we have developed a new Lecture-Tutorial, "Detecting Exoplanets with Gravitational Microlensing." In this paper, we describe how this new Lecture-Tutorial's representations of astrophysical phenomena, which we selected and created based on theoretically motivated considerations of their pedagogical affordances, are used to help introductory astronomy students develop more expert-like reasoning abilities.Comment: 10 pages, 10 figures, accepted for publication in the American Journal of Physic

Missouri hog farmers : factors affecting production decisions

Cover title.Includes bibliographical references (page 19)

Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry

International audienceContinuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS) were carried out in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area ? 2006 campaign (MCMA-2006) between 7?27 March, 2006. Biomass and organic carbon (OC) particle types were found to dominate the accumulation mode both day and night. The concentrations of both organic carbon and biomass particles were roughly equal early in the morning, but biomass became the largest contributor to the accumulation mode mass from the late morning until early evening. The diurnal pattern can be attributed to aging and/or a change in meteorology. Fresh elemental carbon (EC) particles were observed during rush hour. The majority of the EC particles were mixed with nitrate, sulfate, organic carbon and potassium. Submicron particles from industrial sources in the northeast were composed of an internal mixture of Pb, Zn, EC and Cl and peaked early in the morning. A unique nitrogen-containing organic (NOC) particle type was observed, and is hypothesized to be from industrial emissions based on the temporal profile and back trajectory analysis. This study provides unique insights into the real-time changes in single particle mixing state as a function of size and time for aerosols in Mexico City. These new findings indicate that biomass burning and industrial operations make significant contributions to particles in Mexico City. These sources have received relatively little attention in previous intensive field campaigns

Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry

Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS) were made in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area-2006 campaign (MCMA-2006). Results are presented for the period of 15–27 March 2006. The submicron size mode contained both fresh and aged biomass burning, aged organic carbon (OC) mixed with nitrate and sulfate, elemental carbon (EC), nitrogen-organic carbon, industrial metal, and inorganic NaK inorganic particles. Overall, biomass burning and aged OC particle types comprised 40% and 31%, respectively, of the submicron mode. In contrast, the supermicron mode was dominated by inorganic NaK particle types (42%) which represented a mixture of dry lake bed dust and industrial NaK emissions mixed with soot. Additionally, aluminosilicate dust, transition metals, OC, and biomass burning contributed to the supermicron particles. Early morning periods (2–6 a.m.) showed high fractions of inorganic particles from industrial sources in the northeast, composed of internal mixtures of Pb, Zn, EC and Cl, representing up to 73% of the particles in the 0.2–3μm size range. A unique nitrogen-containing organic carbon (NOC) particle type, peaking in the early morning hours, was hypothesized to be amines from local industrial emissions based on the time series profile and back trajectory analysis. A strong dependence on wind speed and direction was observed in the single particle types that were present during different times of the day. The early morning (3:30–10 a.m.) showed the greatest contributions from industrial emissions. During mid to late mornings (7–11 a.m.), weak northerly winds were observed along with the most highly aged particles. Stronger winds from the south picked up in the late morning (after 11 a.m.), resulting in a decrease in the concentrations of the major aged particle types and an increase in the number fraction of fresh biomass particles. The highest wind speeds were correlated with the highest number fraction of fresh biomass particles (up to 76% of the submicron number fraction) when winds were coming directly from fires that were located south and southeast of the city based on MODIS fire count data. This study provides a unique clock of hourly changes in single particle mixing state and sources as a function of meteorology in Mexico City. These new findings indicate that biomass burning and industrial emissions can make significant contributions to primary particle loadings in Mexico City that are strongly coupled with local meteorology

Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol

After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (κapp). Throughout all blooms, κapp ranged between 0.7 and 1.4 (average 0.95 ± 0.15), consistent with laboratory investigations using algae‐produced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in κapp associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds.Key PointsChanges in seawater and sea spray composition did not strongly affect expected CCN concentrationsBlooms may impact clouds more strongly through changes in aerosol flux or secondary chemistryModel parameterizations likely overestimate changes in cloud nuclei due to primary marine organicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/1/grl54978_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/2/grl54978-sup-0001-supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/3/grl54978.pd

Evaluating Greek equity funds using data envelopment analysis

This study assesses the relative performance of Greek equity funds employing a non-parametric method, specifically Data Envelopment Analysis (DEA). Using an original sample of cost and operational attributes we explore the e¤ect of each variable on funds' operational efficiency for an oligopolistic and bank-dominated fund industry. Our results have significant implications for the investors' fund selection process since we are able to identify potential sources of inefficiencies for the funds. The most striking result is that the percentage of assets under management affects performance negatively, a conclusion which may be related to the structure of the domestic stock market. Furthermore, we provide evidence against the notion of funds' mean-variance efficiency

Gene Discovery and Functional Genomics in the Pig

Advances in gene mapping and genomics in farm animals have been considerable over the past decade. Medium resolution linkage and physical maps have been reported, and specific chromosomal regions and genes associated with traits of biological and economic interest have been identified. We have reached an exciting stage in gene identification, mapping and quantitative trait locus discovery in pigs, as new molecular information is accumulating rapidly. Significant progress has been made by identifying candidate gene associations and low-resolution regions containing quantitative trail loci (QTL). However, we are still disadvantaged by the lack of tools available to efficiently use much of this new information. For example, current pig maps are neither of high enough resolution nor sufficiently informative at the comparative level for positional candidate gene cloning within QTL regions. As well, studying biological mechanisms underlying economically important traits such as reproduction is limited by the lack of molecular resources. This is especially important, as reproduction is very difficult to genetically improve by classical breeding methods due to the relatively low heritability and high expense in data collection. Thus, an improved understanding of porcine reproductive biology is of crucial economic importance, yet reproductive processes are poorly characterized at the molecular level. Recently, new methodologies have been brought to bear on a better understanding of pig molecular biology for accelerating genetic improvement in pigs. Several groups are developing molecular information in the pig, and the total Genbank sequence entries for porcine expressed genes have recently topped 100,000. Our Midwest EST Consortium has produced cDNA libraries containing the majority of genes expressed in major female reproductive tissues, and we have deposited nearly 15,000 gene sequences into public databases. These sequences represent over 8,900 different genes, based on sequence comparison among these data. Furthermore, we have developed computer software to automatically extract sequence similarity of these pig genes with their human counterparts, as well as the mapping information of these human homologues. Within our data set, we have identified nearly 1,500 pig genes with strong similarity to mapped human genes, and we are in the process of mapping 700 of these genes to improve the human-pig comparative map. This work and the complementary work of others can now be used to more rapidly understand and identify the genes controlling reproduction, so that genetic improvement of reproduction phenotypes can accelerate