9,902 research outputs found
Non-Market Valuation of Open Space and Other Amenities Associated with Retention of Lands in Agricultural Use
The most productive farmland in southcentral Alaska is currently
under intense development pressure due to rapid population increases
and consequential increases in demand for suburban housing. This
study utilizes a contingent valuation iterative bidding game to estimate
the willingness of Matanuska-Susitna Borough residents to pay to
preserve open space and other historical/environmental amenities
associated with farming activities. Determinants of consumer behavior
are addressed as well as total benefits and costs of various posited
development scenarios. This information may be useful to
policymakers assessing actions designed to purchase development
rights from Matanuska-Susitna farmers
A VON LIEBIG MODEL FOR WATER AND NITROGEN CROP RESPONSE
The century-old “law of the minimum” proposed by von Liebig was tested using five independent sets of crop response data on wheat, corn, cotton, silage, and sugar beets. The rival models were polynomial functions reported in the literature as the most suitable models for interpreting those data. Overall, the von Liebig model performed very well. While the nonnested hypothesis test was inconclusive with regard to silage and sugar beets, the von Liebig model rejected the polynomial specifications for wheat, corn and cotton.Crop Production/Industries,
Performance Indices for Multivariate Ice Hockey Statistics
A Review of the Use of Performance Indices in Ice Hocke
WHO WON THE 1996 NHL PLUS-MINUS AWARD?
Point total, goals plus assists, is an NHL player’s most important individual statistic; it is the best predictor of salary. However, an individual player\u27s goals and assists are only indirectly important to his team because the team objective is to win games and not necessarily to watch individual players run up their point totals. Unfortunately, sometimes opposition teams score easy goals against a team\u27s best goal scorers because these players do not always play well defensively.vAs a result of this conflict, hockey uses a statistic called the plus/minus, (P/M), which purports to measure a player\u27s offensive versus defensive ability
CONSUMERS' WILLINGNESS TO PURCHASE LOCALLY PRODUCED AGRICULTURAL PRODUCTS: AN ANALYSIS OF AN INDIANA SURVEY
Using a survey of over 320 consumers from across the state of Indiana, we estimate an ordered probit model to determine the demographic and attitudinal factors which are most important in predicting the likelihood of consumers to purchase products that are produced within the state. Our results indicate that the willingness to purchase locally produced agricultural products increases with time of residency in the state, and we find a greater tendency for female consumers to purchase such products. We also find that quality perceptions play a critical role in these food purchase-decisions. We underscore the importance of maintaining minimum quality standards to maximize the effectiveness of state level agricultural promotion programs.Consumer/Household Economics,
Liquid cooled helmet
Liquid cooled helmet comprising a cap of flexible material adapted to fit the head of a person, cooling panels mounted inside the cap forming passageways for carrying a liquid coolant, the panels being positioned to engage the cranium and neck of a person wearing the helmet, inlet and outlet lines communicating with the passageways, and releasable straps for securing the helmet about the neck of the wearer
Quantitative Comparison of cis-Regulatory Element (CRE) Activities in Transgenic Drosophila melanogaster
Gene expression patterns are specified by cis-regulatory element (CRE) sequences, which are also called enhancers or cis-regulatory modules. A typical CRE possesses an arrangement of binding sites for several transcription factor proteins that confer a regulatory logic specifying when, where, and at what level the regulated gene(s) is expressed. The full set of CREs within an animal genome encodes the organism′s program for development1, and empirical as well as theoretical studies indicate that mutations in CREs played a prominent role in morphological evolution2-4. Moreover, human genome wide association studies indicate that genetic variation in CREs contribute substantially to phenotypic variation5,6. Thus, understanding regulatory logic and how mutations affect such logic is a central goal of genetics.
Reporter transgenes provide a powerful method to study the in vivo function of CREs. Here a known or suspected CRE sequence is coupled to heterologous promoter and coding sequences for a reporter gene encoding an easily observable protein product. When a reporter transgene is inserted into a host organism, the CRE′s activity becomes visible in the form of the encoded reporter protein. P-element mediated transgenesis in the fruit fly species Drosophila (D.) melanogaster7 has been used for decades to introduce reporter transgenes into this model organism, though the genomic placement of transgenes is random. Hence, reporter gene activity is strongly influenced by the local chromatin and gene environment, limiting CRE comparisons to being qualitative. In recent years, the phiC31 based integration system was adapted for use in D. melanogaster to insert transgenes into specific genome landing sites8-10. This capability has made the quantitative measurement of gene and, relevant here, CRE activity11-13 feasible. The production of transgenic fruit flies can be outsourced, including phiC31-based integration, eliminating the need to purchase expensive equipment and/or have proficiency at specialized transgene injection protocols.
Here, we present a general protocol to quantitatively evaluate a CRE′s activity, and show how this approach can be used to measure the effects of an introduced mutation on a CRE′s activity and to compare the activities of orthologous CREs. Although the examples given are for a CRE active during fruit fly metamorphosis, the approach can be applied to other developmental stages, fruit fly species, or model organisms. Ultimately, a more widespread use of this approach to study CREs should advance an understanding of regulatory logic and how logic can vary and evolve
As pastagens e seu manejo no Centro-Sul do Brasil
Although the cattle industry of south-central Brazil is of great importance to the economy of the country and the nutrition of the people, present pasture practices have only short term viability. The continuing decrease in productivity of pasture lands has led to consideration of legumes and fertilization to satisfy the primary need for nitrogen. Both alternatives are examined and in conclusion the establishment of legumes is economically viable depending on site conditions and distance from market. Adequate provisions for seasonal shortages, and the establishment of rotational grazing systems are also essential.A indústria pecuária do centro-sul brasileiro constitui importante contribuição para a economia nacional e para a alimentação das populações. Contudo, percebe-se que os atuais métodos de pastoreio não podem continuar por muito tempo. A produtividade das pastagens vem diminuindo constantemente; e isso levou a pensar no uso das leguminosas e na fertilização das terras, para suprir a necessidade primária de nitrogênio. Ambas as alternativas foram examinadas, concluindo-se que o estabelecimento de leguminosas é economicamente viável, dependendo das condições da localização e distância do mercado; mas é necessário também fazer provisões para os períodos de escassez, bem como implantar o sistema da rotatividade dos pastos
Merged ionization/dissociation fronts in planetary nebulae
The hydrogen ionization and dissociation front around an ultraviolet
radiation source should merge when the ratio of ionizing photon flux to gas
density is sufficiently low and the spectrum is sufficiently hard. This regime
is particularly relevant to the molecular knots that are commonly found in
evolved planetary nebulae, such as the Helix Nebula, where traditional models
of photodissociation regions have proved unable to explain the high observed
luminosity in H_2 lines. In this paper we present results for the structure and
steady-state dynamics of such advection-dominated merged fronts, calculated
using the Cloudy plasma/molecular physics code. We find that the principal
destruction processes for H_2 are photoionization by extreme ultraviolet
radiation and charge exchange reactions with protons, both of which form H_2^+,
which rapidly combines with free electrons to undergo dissociative
recombination. Advection moves the dissociation front to lower column densities
than in the static case, which vastly increases the heating in the partially
molecular gas due to photoionization of He^0, H_2, and H^0. This causes a
significant fraction of the incident bolometric flux to be re-radiated as
thermally excited infrared H_2 lines, with the lower excitation pure rotational
lines arising in 1000 K gas and higher excitation H_2 lines arising in 2000 K
gas, as is required to explain the H_2 spectrum of the Helix cometary knots.Comment: 4 pages, accepted by ApJL, scheduled December 20 issu
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