1,094 research outputs found
AN ECONOMIC ANALYSIS OF GENETIC INFORMATION: LEPTIN GENOTYPING IN FED CATTLE
The use of genetic knowledge is widespread in crop production but is just recently being utilized in livestock production. This study investigates the economic value to feedlots of a polymorphism in the bovine leptin gene. Previous studies indicate that this polymorphism is associated with fat deposition. Since fed cattle are often priced on a grid that considers both yield and quality grades, fat deposition is an important factor in the value and profitability of fed cattle. Using data from 590 crossbred steers and heifers, we estimate growth curves for relevant biological traits, both with and without genotypic information. Using the resulting functions, we then simulate carcass traits to various days-on-feed and compute the associated profit under three price grids. Maximum profits are determined in an unconstrained profit maximization model and in a model that constrains cattle to be marketed in 45-head "potloads." Results indicate that leptin genotypic knowledge has little impact on optimal days-on-feed but may play a role in valuing feeder cattle. The differences in value of cattle varied by as much as $37 per head between genotypes.genetics, leptin genotype, beef cattle, value of information, Livestock Production/Industries,
A Comprehensive Measure of the Costs of Caring For a Parent: Differences According to Functional Status
Providing unpaid care for an older parent has costs that go well beyond a caregiver’s lost wages. A new estimate suggests that the median direct and indirect costs of caregiving are 277 billion in 2011, which is 20 percent higher than estimates that only consider lost wages
Observations on the Formation of Massive Stars by Accretion
Observations of the H66a recombination line from the ionized gas in the
cluster of newly formed massive stars, G10.6-0.4, show that most of the
continuum emission derives from the dense gas in an ionized accretion flow that
forms an ionized disk or torus around a group of stars in the center of the
cluster. The inward motion observed in the accretion flow suggests that despite
the equivalent luminosity and ionizing radiation of several O stars, neither
radiation pressure nor thermal pressure has reversed the accretion flow. The
observations indicate why the radiation pressure of the stars and the thermal
pressure of the HII region are not effective in reversing the accretion flow.
The observed rate of the accretion flow, 0.001 solar masses/yr, is sufficient
to form massive stars within the time scale imposed by their short main
sequence lifetimes. A simple model of disk accretion relates quenched HII
regions, trapped hypercompact HII regions, and photo-evaporating disks in an
evolutionary sequence
Distribution, habitat associations, and conservation status updates for the pilose crayfish Pacifastacus gambelii (Girard, 1852) and Snake River pilose crayfish Pacifastacus connectens (Faxon, 1914) of the western United States
Our study evaluates the distribution, habitat associations, and current conservation status of the Snake River pilose crayfish Pacifastacus connectens (Faxon, 1914) and pilose crayfish Pacifastacus gambelii (Girard, 1852), two little-studied and data-deficient species endemic to the western United States. We first developed a species distribution model (SDM) for the pilose crayfishes based on their historical occurrence records using boosted regression trees and freshwater GIS data layers. We then sampled 163 sites in the summers of 2016 and 2017 within the distribution of these crayfishes, including 50 where these species were observed historically. We next compared our field results to modeled predictions of suitable habitat from the SDM. Our SDM predicted 73 sites (45%) we sampled as suitable for the pilose crayfishes, with a moderate AUC value of 0.824. The pilose crayfishes were generally predicted to occur in larger streams and rivers with less extreme upstream temperature and precipitation seasonality. We found the pilose crayfishes at only 20 (12%) of the 163 total sites we sampled, 14 (20%) of the 73 sites predicted as suitable for them by our SDM, and 12 (24%) of 50 historical sites that we sampled. We found the invasive virile crayfish Faxonius virilis (Hagen, 1870) at 22 sites total and 12 (24%) historical sites for the pilose crayfishes, and we found the “native invader” signal crayfish Pacifastacus leniusculus (Dana, 1852) at 29 sites total and 6 (12%) historical sites for the pilose crayfishes. We subsequently used a single classification tree to identify factors associated with our high rate of false positives for contemporary pilose crayfish distributions relative to our SDM. This classification tree identified the presence of invasive crayfishes, impairment of the benthic community, and sampling method as some of the factors differentiating false positives relative to true positives for the pilose crayfishes. Our study identified the historical distribution and habitat associations for P. connectens and P. gambelii using an SDM and contrasted this prediction to results of contemporary field sampling. We found that the pilose crayfishes have seemingly experienced substantial range declines, attributable to apparent displacement by invasive crayfishes and impairment or change to stream communities and habitat. We recommend increased conservation and management attention to P. connectens and P. gambelii in response to these findings
Calcium cabonate saturation index and alkalinity interpretations
Reprint. Originally published: Journal of the American Water Works Association ; v. 34, no. 11 (November 1942).Includes bibliographical references
Inferring Quantum Network Topology using Local Measurements
Statistical correlations that can be generated across the nodes in a quantum
network depend crucially on its topology. However, this topological information
might not be known a priori, or it may need to be verified. In this paper, we
propose an efficient protocol for distinguishing and inferring the topology of
a quantum network. We leverage entropic quantities -- namely, the von Neumann
entropy and the measured mutual information -- as well as measurement
covariance to uniquely characterize the topology. We show that the entropic
quantities are sufficient to distinguish two networks that prepare GHZ states.
Moreover, if qubit measurements are available, both entropic quantities and
covariance can be used to infer the network topology. We show that the protocol
can be entirely robust to noise and can be implemented via quantum variational
optimization. Numerical experiments on both classical simulators and quantum
hardware show that covariance is generally more reliable for accurately and
efficiently inferring the topology, whereas entropy-based methods are often
better at identifying the absence of entanglement in the low-shot regime
A Programmable True Random Number Generator Using Commercial Quantum Computers
Random number generators (RNG) are essential elements in many cryptographic
systems. True random number generators (TRNG) rely upon sources of randomness
from natural processes such as those arising from quantum mechanics phenomena.
We demonstrate that a quantum computer can serve as a high-quality, weakly
random source for a generalized user-defined probability mass function (PMF).
Specifically, QC measurement implements the process of variate sampling
according to a user-specified PMF resulting in a word comprised of electronic
bits that can then be processed by an extractor function to address
inaccuracies due to non-ideal quantum gate operations and other system biases.
We introduce an automated and flexible method for implementing a TRNG as a
programmed quantum circuit that executes on commercially-available, gate-model
quantum computers. The user specifies the desired word size as the number of
qubits and a definition of the desired PMF. Based upon the user specification
of the PMF, our compilation tool automatically synthesizes the desired TRNG as
a structural OpenQASM file containing native gate operations that are optimized
to reduce the circuit's quantum depth. The resulting TRNG provides multiple
bits of randomness for each execution/measurement cycle; thus, the number of
random bits produced in each execution is limited only by the size of the QC.
We provide experimental results to illustrate the viability of this approach.Comment: 15 pages, 7 figures, SPIE Defense + Commercial Sensing: Quantum
Information Science, Sensing, and Computation X
Chromatographic separation and identification of organic acids: Application to detection of organic acids in river waters
Reprint. Originally published: Analytical chemistry ; v. 32 (May 1960).Caption title.Includes bibliographical references
Reproductive Ecology Of The Florida Scrub-Jay (Aphelocoma Coerulescens) On John F. Kennedy Space Center/Merritt Island National Wildlife Refuge: A Long-Term Study
From 1988 to 2002 we studied the breeding ecology of Florida Scrub-Jays (Aphelocoma coerulescens) on John F. Kennedy Space Center/Merritt Island National Wildlife Refuge. We examined phenology, clutch size, hatching failure rates, fledgling production, nest success, predation rates, sources egg and nestling mortality, and the effects of helpers on these measures. Nesting phenology was similar among sites. Mean clutch size at Titan was significantly larger than at HC or T4. Pairs with helpers did not produce larger clutches than pairs without helpers. Fledgling production at T4 was significantly greater than at HC and similar to Titan. Pairs with helpers at HC produced significantly more fledglings than pairs without helpers; helpers did not influence fledgling production at the other sites. Nest success at HC and Titan was low, 19% and 32% respectively. Nest success at T4 was 48% and was significantly greater than at HC. Average predation rates at all sites increased with season progression. Predation rates at all sight rose sharply by early June. The main cause of nest failure at all sites was predation, 93%
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