524 research outputs found

    Objective Climate Model Predictions Using Jeffreys' Prior: the General Multivariate Normal Case

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    Objective probabilistic forecasts of future climate that include parameter uncertainty can be made by using the Bayesian prediction integral with the prior set to Jeffreys' Prior. The calculations involved in determining the prior can then be simplified by making parametric assumptions about the distribution of the output from the climate model. The most obvious assumption to make is that the climate model output is normally distributed, in which case evaluating the prior becomes a question of evaluating gradients in the parameters of the normal distribution. In previous work we have considered the special cases of diagonal (but not constant) covariance matrix, and constant (but not diagonal) covariance matrix. We now derive expressions for the general multivariate normal distribution, with non-constant non-diagonal covariance matrix. The algebraic manipulation required is more complex than for the special cases, and involves some slightly esoteric matrix operations including taking the expectation of a vector quadratic form and differentiating the determinants, traces and inverses of matrices

    An Inter-Sector Impact of Hurricanes Katrina and Rita On The Agribusiness Industry In Mississippi

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    This study evaluates the impact of hurricanes Katrina and Rita on the agribusiness industry and related sectors in Mississippi. Input-output analysis was used to determine the economic impact of these disasters on the Mississippi agribusiness sector and related sectors in the state's economy.agribusiness, economic impact, input-output analysis, temporal effects, agribusiness sector, related sectors, Agribusiness,

    The Economic impact of Repealing Mississippi's Grocery Tax

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    Results from the analyses indicate that repealing the 7 percent grocery tax would produce modest gains in grocery sales but major increases in the purchases of other goods and services. Revenues from the sale of additional groceries would be exempt from taxes, thus producing only employment and labor income. With the state loosing almost $202 million in tax revenues, it is not clear if the gains in employment would be enough to offset the revenue losses.Agribusiness, Public Economics,

    The Structure Performance Hypothesis and The Efficient Structure Performance Hypothesis-Revisited: The Case of Agribusiness Commodity and Food Products Truck Carriers in the South

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    Two competing hypotheses on market structure and performance of firms are the traditional structure-conduct-performance (SCP) paradigm and the efficiency structure hypothesis. This paper reveals the profits made by firms in the trucking industry were because of greater efficiencies than their competitors and not because of collusive activities.Public Economics,

    Are changes in global precipitation constrained by the tropospheric energy budget?

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    Copyright © 2009 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act September 2010 Page 2 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or [email protected] tropospheric energy budget argument is used to analyze twentieth-century precipitation changes. It is found that global and ocean-mean general circulation model (GCM) precipitation changes can be understood as being due to the competing direct and surface-temperature-dependent effects of external climate forcings. In agreement with previous work, precipitation is found to respond more strongly to anthropogenic and volcanic sulfate aerosol and solar forcing than to greenhouse gas and black carbon aerosol forcing per unit temperature. This is due to the significant direct effects of greenhouse gas and black carbon forcing. Given that the relative importance of different forcings may change in the twenty-first century, the ratio of global precipitation change to global temperature change may be quite different. Differences in GCM twentieth- and twenty-first-century values are tractable via the energy budget framework in some, but not all, models. Changes in land-mean precipitation, on the other hand, cannot be understood at all with the method used here, even if land–ocean heat transfer is considered. In conclusion, the tropospheric energy budget is a useful concept for understanding the precipitation response to different forcings but it does not fully explain precipitation changes even in the global mean


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    An input/output model was developed to estimate the potential economic impact of intentional attacks by agricultural terrorists using Exotic Newcastle Disease (END) on the poultry industry in Mississippi. The model measured impacts in terms of income, employment, output, and tax changes in the poultry industry.Risk and Uncertainty,

    An Analysis of Trends in Food Import Refusals in the United States

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    Millions of pounds of fresh fruits, vegetables, cut flowers, herbs, and other agricultural and food products enter the United States via commercial shipments from other countries every year. Although these items appear harmless, there could be hidden threats in that baggage and in those truckloads, trainloads, and containers of fresh and processed food items that could seriously threaten U.S. agriculture, its natural resources, and its economy (U.S. Customs and Border Protection 2007). Food imports play a major role in the success and competitiveness of various agribusiness firms in the United States. For example, food imports generate income, employment, output, and taxes and provide consumers with lower-priced products than those produced or purchased in the domestic markets. Food imports also provide consumers with a larger variety of products that normally would not be available to them, or that would be available in limited quantities and at higher than normal prices. Consequently, without food imports many U.S. food processing and manufacturing firms would be forced to reduce plant capacity, re-locate food processing and manufacturing facilities, or close plants altogether (Rosson 2000). Thus it is important that food imports that do not comply with U.S. standards be targeted, detected, and intercepted, thereby preventing the entry of those potential threats before they have the chance to do any harm to the U.S food system and its infrastructure.Agribusiness, International Relations/Trade,

    Reassessing the Duration of the Second Stage of Labor in Relation to Maternal and Neonatal Morbidity.

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    OBJECTIVE: To assess the morbidity associated with continuing the second-stage duration of labor, weighing the probability of spontaneous vaginal birth without morbidity compared with birth with serious maternal or neonatal complications. METHODS: In a retrospective cohort, we analyzed singleton, vertex births at 36 weeks of gestation or greater without prior cesarean delivery (n=43,810 nulliparous and 59,605 multiparous women). We calculated rates of spontaneous vaginal birth and composite serious maternal or neonatal complications. Results were stratified by parity (nulliparous or multiparous) and epidural status (yes or no). Competing risks models were created for 1) spontaneous vaginal birth with no morbidity, 2) birth with maternal or neonatal morbidity, and 3) no spontaneous vaginal birth and no morbidity, and our main interest was in comparing number 1 against number 2. RESULTS: Rates of spontaneous vaginal birth without morbidity were slightly higher after the first half hour (greater than 0.5-1.0 hours) for nulliparous women, after which rates decreased with increasing second-stage duration. For multiparous women, rates of spontaneous vaginal birth without morbidity decreased with increasing second-stage duration. For illustration, for a nulliparous woman with an epidural at 3.0 hours of the second stage of labor who extended by another 1.0 hour, her likelihood of delivering by spontaneous vaginal birth was 31.4% compared with her likelihood of birth with any serious complication in the subsequent hour, which was 7.6%. The percentage of cesarean deliveries for nonreassuring fetal heart rate tracing were higher for women without compared with women with an epidural. CONCLUSION: Rates of spontaneous vaginal birth without serious morbidity steadily decreased for increasing second-stage duration except for the first half hour for nulliparous women. We did not observe an inflection point at a particular hour mark for either spontaneous vaginal delivery without morbidity or births with morbidity. Our findings will assist in decision-making for extending second-stage duration