The extinct Carolina Parakeet (Conuropsis carolinensis) once was part of the Arkansas avifauna. The first two reports of the species in what is now Arkansas were made in 1673 and 1718 by early French explorers. The remaining records are from the 1800s when parakeets were found in nearly all parts of the state, often in abundance. The last literature reference for the species still definitely occurring in Arkansas pertains to birds present in the summer of 1885 along the White River at Newpor
The moduli space of stable real cubic surfaces is the quotient of real
hyperbolic four-space by a discrete, nonarithmetic group. The volume of the
moduli space is 37\pi^2/1080 in the metric of constant curvature -1. Each of
the five connected components of the moduli space can be described as the
quotient of real hyperbolic four-space by a specific arithmetic group. We
compute the volumes of these components.Comment: 4 pages, one figur
Let M_0^R be the moduli space of smooth real cubic surfaces. We show that
each of its components admits a real hyperbolic structure. More precisely, one
can remove some lower-dimensional geodesic subspaces from a real hyperbolic
space H^4 and form the quotient by an arithmetic group to obtain an orbifold
isomorphic to a component of the moduli space. There are five components. For
each we describe the corresponding lattices in PO(4,1). We also derive several
new and several old results on the topology of M_0^R. Let M_s^R be the moduli
space of real cubic surfaces that are stable in the sense of geometric
invariant theory. We show that this space carries a hyperbolic structure whose
restriction to M_0^R is that just mentioned. The corresponding lattice in
PO(4,1), for which we find an explicit fundamental domain, is nonarithmetic.Comment: Major revision, including several new or completely rewritten
sections. 56 page
In partially ionised plasmas, the magnetic field can become decoupled from
the neutral gas and diffuse through it in a process known as ambipolar
diffusion. Although ambipolar diffusion has been implemented in several grid
codes, we here provide an implementation in smoothed particle
magnetohydrodynamics (SPMHD). We use the strong coupling approximation in which
the ion density is negligible, allowing a single fluid approach. The equations
are derived to conserve energy, and to provide a positive definite contribution
to the entropy. We test the implementation in both a simple 1D SPMHD code and
the fully 3D code PHANTOM. The wave damping test yields agreement within 0.03-2
per cent of the analytical result, depending on the value of the collisional
coupling constant. The oblique C-shocks test yields results that typically
agree within 4 per cent of the semi-analytical result. Our algorithm is
therefore suitable for exploring the effect ambipolar diffusion has on physical
processes, such as the formation of stars from molecular clouds.Comment: Accepted for publication by MNRA
This study measures the welfare changes in agriculture and to consumers should people eat the recommended levels of fruits and vegetables for a cancer prevention diet. An equilibrium displacement model is used to measure the change in welfare to fruit and vegetable industries, other commodities, and agricultural input markets.Food Consumption/Nutrition/Food Safety,
This study will estimate the benefits to fruit and vegetable industries and consumers should people in the U.S. meet the USDA minimum dietary guidelines. Specifically the objectives of the study are to 1) estimate the benefits to fruit and vegetable industries and consumers should people eat the general and subgroup 7-a-day and 9-a-day recommendation; 2) estimate the benefits should smaller increases of only 10 percent or 25 percent be achieved; and 3) determine how agricultural inputs, including land and labor, would be affected by the increase in demand for fruits and vegetables. To protect against the incidence of chronic diseases such as diabetes, cardiovascular disease and cancer the 2005 USDA dietary guidelines recommend the consumption of 3 to 4 fruit servings and 4 to 5 vegetable servings a day. They also provide recommendations on the composition of fruit and vegetable consumption as well as the level. For example, almost one serving of dark leafy vegetables is recommended per day. Depite the known health benefits, many people do not eat the amounts recommended in the USDA dietary guidelines and low income consumers (those whose median household income is less than 25,000ayear)eatfewerservings.BasedontheNHANES4(Nationalhealthandnutritionexaminationsurvey)andNHANES5,averageconsumptionoffruitbylow−incomeconsumerswouldneedtoincreasebyatleast83percentatmeetthe3adayrecommendationand39percentinordertomeetthe4adayrecommendation.Peopleinhigher−incomehouseholdsonlyneedtoincreaseconsumptionbyonly60percentforfruitand30percentforvegetables.Theproportionalincreasesinconsumptionassumethatpeoplenolongereatpotatochipsorfrenchfriesinordertomeetdietaryguidelinesonfatconsumption.Ashiftinconsumptionpatternstotherecommendedlevelswouldcausethedemandforfruitsandvegetablestorisesignificantly,leadingtohigherpricesandincreasedproduction,shiftingtheuseofagriculturalresources(suchasland,labor,andwater)intotheproductionofthosecommodities,andbenefitingtheentireagriculturalsector.Despitethepotentialgainstoagriculture,thesevalueshavebeenignoredinpreviousstudiesofimprovednutrientintake.Suchabenefittoproducersmightjustifyadditionalpublicsectorinvestmentinpromotinghealthierdiets.Thechangesinprices,agriculturalproduction,agriculturalinputusage,andtradewillbesimulatedusinganequilibriumdisplacementmodel.Thedualapproachusedinthisanalysislaysoutbasicdemandandsupplyequationsfromdemandandcostfunctionstoshowhowequilibriumconditionschangeinresponsetoshocks,suchasanincreaseinthedemandforfruitsandvegetables.Thefunctionscharacterizethefinalmarket,allowforsubstitutabilitybetweenmarketingandnon−marketinginputsinthemarketingsector,includesthefarmsector,andchangesininputuseresultingfromchangesincropmixandsubstitutabilityinland,laborandotherinputs.Equilibriumdisplacementmodelshavebeenwidelyusedtoestimatethebenefitsofagriculturalresearchagriculturalpoliciesandthebenefitstothedairyindustryofasocialmarketingprogramtomiddleschoolchildren.Themodelisparameterizedwithfarm,marketandconsumptiondata.TheincreaseinfruitandvegetableconsumptionismodeledasashiftinthedemandcurvewiththeshiftequaltothepercentageincreaseneededtomeettheUSDAdietaryguidelines.Producersurplusisestimatedfromthechangesingrowerpricesandagriculturalproduction,lesschangesinthecostofinputs.Consumersurplusforpeoplelivinginlow−incomehouseholds(lessthan25,000 a year median income) and higher income households is estimated from the changes in retail prices and final market quantities consumed by each income group.Food Consumption/Nutrition/Food Safety,