17,353 research outputs found
Writer Corrected on Miseducation
Response by School of Living member to article from the Dayton Daily News of Sunday, July 10, 1966 titled Green Revolutionaries Battle for Back to Nature Society by Doug Walker
Quantum Computing with an 'Always On' Heisenberg Interaction
Many promising ideas for quantum computing demand the experimental ability to
directly switch 'on' and 'off' a physical coupling between the component
qubits. This is typically the key difficulty in implementation, and precludes
quantum computation in generic solid state systems, where interactions between
the constituents are 'always on'. Here we show that quantum computation is
possible in strongly coupled (Heisenberg) systems even when the interaction
cannot be controlled. The modest ability of 'tuning' the transition energies of
individual qubits proves to be sufficient, with a suitable encoding of the
logical qubits, to generate universal quantum gates. Furthermore, by tuning the
qubits collectively we provide a scheme with exceptional experimental
simplicity: computations are controlled via a single 'switch' of only six
settings. Our schemes are applicable to a wide range of physical
implementations, from excitons and spins in quantum dots through to bulk
magnets.Comment: 4 pages, 3 figs, 2 column format. To appear in PR
The Effect of Recombinant Bovine Somatotropin on Patterns of Milk Production, Lactational Milk Estimates and Net Farm Income
Bovine somatoropin (bST) alters total milk production and production patterns in dairy cows and understanding the economic benefits of bST for the dairy producer are critical. Holstein cows (n = 555) from four Michigan dairy farms were randomly assigned as untreated controls or to receive 500 mg of bovine somatotropin (PosilacR) administered every 14 days beginning at 63 to 69 days of lactation and continuing until approximately 21 days prior to the end of lactation or until the animal was removed from the herd. Average peak milk production was 50.8 kg / day and occurred at an average of 113 9 days of lactation for bST-treated cows while average peak production was 48.9 kg / day occurring at an average of 86.4 days of lactation for control cows; both parameters were significantly greater for bST-treated cows compared to controls. Study cows treated with bST were significantly more persistent in lactation (7% greater lactational persistency) compared to control cows. All DHIA estimates and actual milk produced were not significantly different between the study treatment groups for any of the four comparisons made (first, second, third monthly tests after bST treatment initiation and final (305-day) DHIA production estimates); however, the accuracy of DHIA production estimates was significantly affect by the amount of time elapsed since bST but became non-significant by the third DHIA test date. The use of bST changed NFI for each of the four study farms by 3.57, 7.15) per bST-treated cow, respectively during the trial period (from 63 to 305 days of lactation). The overall average change in NFI attributable to bST was $43.01 per bST-treated cow. 2 Profitability of bST use was observed to be quite variable between farms studied because many factors were found to affect the change in NFI per cow resulting from bST use; the level of production response and the price received for milk had the largest effects on the change in NFI associated with bST use; by contrast, price paid for bST itself and feed had only minimal effects on bST-associated profitability. Diseases that may be associated with bST may reduce the profitability of this product and need to be considered as a cost of bST use if present.bovine somatotropin, dairy, net farm income, Farm Management, Livestock Production/Industries, Productivity Analysis, Research and Development/Tech Change/Emerging,
Substituted phenylarsonic acids; structures and spectroscopy
Full NMR and ESI-MS spectra, and differential scanning calorimeter data are presented for 15 substituted phenylarsonic acids, including two new fluoro-substituted examples. X-ray crystal structure determinations of five examples (phenylarsonic acid and the 4-fluoro-, 4-fluoro-3-nitro-, 3-amino-4-hydroxy- and 3-amino-4-methoxy-substituted derivatives) were determined and the H-bonding crystal-packing patterns analysed
Towards practical classical processing for the surface code: timing analysis
Topological quantum error correction codes have high thresholds and are well
suited to physical implementation. The minimum weight perfect matching
algorithm can be used to efficiently handle errors in such codes. We perform a
timing analysis of our current implementation of the minimum weight perfect
matching algorithm. Our implementation performs the classical processing
associated with an nxn lattice of qubits realizing a square surface code
storing a single logical qubit of information in a fault-tolerant manner. We
empirically demonstrate that our implementation requires only O(n^2) average
time per round of error correction for code distances ranging from 4 to 512 and
a range of depolarizing error rates. We also describe tests we have performed
to verify that it always obtains a true minimum weight perfect matching.Comment: 13 pages, 13 figures, version accepted for publicatio
Buyer power in U.K. food retailing: a 'first-pass' test
Habtu Weldegebriel, University of Warwick
Abstract
The potential existence of buyer power in U.K. food retailing has attracted the scrutiny of the U.K.'s anti-trust authorities, culminating in the second of two comprehensive regulatory inquiries in recent years. Such inquiries are authoritative but correspondingly time-consuming and costly. Moreover, detection of buyer power has been dogged by the paucity of reliable evidence of its existence. In this paper, we present a simple theoretical model of oligopsony which delivers quasi-reduced form retailer-producer pricing equations with which the null of perfect competition can be tested using readily available market data. Using a cointegrated vector autoregression, we find empirical results that show the null of perfect competition can be rejected in seven of the nine food products investigated. Though not conclusive on the existence of buyer power, the proposed test offers a means via which the behaviour of the retail-producer price spread is consistent with it. At the very least, it can corroborate the concerns of the anti-trust authorities as to whether buyer power is potentially one source of concern
A quantum-mechanical Maxwell's demon
A Maxwell's demon is a device that gets information and trades it in for
thermodynamic advantage, in apparent (but not actual) contradiction to the
second law of thermodynamics. Quantum-mechanical versions of Maxwell's demon
exhibit features that classical versions do not: in particular, a device that
gets information about a quantum system disturbs it in the process. In
addition, the information produced by quantum measurement acts as an additional
source of thermodynamic inefficiency. This paper investigates the properties of
quantum-mechanical Maxwell's demons, and proposes experimentally realizable
models of such devices.Comment: 13 pages, Te
Standardization and quality control in data collection and assessment of threatened plant species
Informative data collection is important in the identification and conservation of rare plant species. Data sets generated by many small-scale studies may be integrated into large, distributed databases, and statistical tools are being developed to extract meaningful information from such databases. A diversity of field methodologies may be employed across smaller studies, however, resulting in a lack of standardization and quality control, which makes integration more difficult. Here, we present a case study of the population-level monitoring of two threatened plant species with contrasting life history traits that require different field sampling methodologies: the limestone glade bladderpod, Physaria filiformis, and the western prairie fringed orchid, Plantanthera praeclara. Although different data collection methodologies are necessary for these species based on population sizes and plant morphology, the resulting data allow for similar inferences. Different sample designs may frequently be necessary for rare plant sampling, yet still provide comparable data. Various sources of uncertainty may be associated with data collection (e.g., random sampling error, methodological imprecision, observer error), and should always be quantified if possible and included in data sets, and described in metadata. Ancillary data (e.g., abundance of other plants, physical environment, weather/climate) may be valuable and the most relevant variables may be determined by natural history or empirical studies. Once data are collected, standard operating procedures should be established to prevent errors in data entry. Best practices for data archiving should be followed, and data should be made available for other scientists to use. Efforts to standardize data collection and control data quality, particularly in small-scale field studies, are imperative to future cross-study comparisons, meta-analyses, and systematic reviews
Observer error in sampling a rare plant population
Background: Estimation of abundance in vegetation sampling involving observers is almost always characterised by observer error, although such error is rarely reported. Aims: To quantify observer error in population estimation of the rare plant species Physaria filiformis in Missouri, USA. Methods: The abundance of P. filiformis was estimated within 25-m2 plots by six trained observers with varying experience levels over 10 years. Observers assigned plots to six predefined density classes. A total of 477 plots were estimated annually, and actual counts were conducted on ca. 10% of the plots to assess per cent agreement of estimates with counts. Results: Over a third of the estimates of plant abundance evaluated for accuracy (36.4%) deviated from exhaustive counts. The majority of the misestimates were underestimates by one density class (29.4%). The number and type of misestimates varied systematically with density class. Conclusions: Observer error could be explained to some degree by variation in population density, but not by experience. It appears that inherent differences exist among observers that cannot be entirely compensated for by experience or training. Observer error in this system represents a systematic bias, and can be compensated for by use of correction factors, which would ideally be both density class-dependent and observer-specific
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