45,060 research outputs found
A dual-beam actinic light source for photosynthesis research
Simulation of photosynthetic process in plants is accomplished by using two separate and identical optical channels that provide independently adjustable wavelengths (filters), shutter sequencing, and control intensity of illumination. In addition to experiments using electron paramagnetic resonance spectroscopy, system may be applicable to other types of research in photosynthetic field
Do television and electronic games predict children's psychosocial adjustment? Longitudinal research using the UK Millennium Cohort Study
Background: Screen entertainment for young children has been associated with several aspects of psychosocial adjustment. Most research is from North America and focuses on television. Few longitudinal studies have compared the effects of TV and electronic games, or have investigated gender differences.
Purpose: To explore how time watching TV and playing electronic games at age 5 years each predicts change in psychosocial adjustment in a representative sample of 7 year-olds from the UK.
Methods: Typical daily hours viewing television and playing electronic games at age 5 years were reported by mothers of 11 014 children from the UK Millennium Cohort Study. Conduct problems, emotional symptoms, peer relationship problems, hyperactivity/inattention and prosocial behaviour were reported by mothers using the Strengths and Difficulties Questionnaire. Change in adjustment from age 5 years to 7 years was regressed on screen exposures; adjusting for family characteristics and functioning, and child characteristics.
Results: Watching TV for 3 h or more at 5 years predicted a 0.13 point increase (95% CI 0.03 to 0.24) in conduct problems by 7 years, compared with watching for under an hour, but playing electronic games was not associated with conduct problems. No associations were found between either type of screen time and emotional symptoms, hyperactivity/inattention, peer relationship problems or prosocial behaviour. There was no evidence of gender differences in the effect of screen time.
Conclusions: TV but not electronic games predicted a small increase in conduct problems. Screen time did not predict other aspects of psychosocial adjustment. Further work is required to establish causal mechanisms
Reliable and robust molecular sexing of the hen harrier (Circus cyaneus) using PCR-RFLP of the CHD1 gene
The hen harrier (Circus cyaneus) is a bird of prey that is persecuted in the United Kingdom, and there is a need for a DNA-based individual identification and sexing system for the use in forensic investigations. This study reports a new set of PCR primers for the chromo-helicase-DNA-binding protein 1 gene, which allows sexing using PCR-RFLP. Instead of exonic primers that amplify across a large intron, this set consists of a primer within the intron, enabling reduction in amplicon sizes from 356 to 212 bp and 565 to 219 bp in W and Z chromosomes. DNA degradation and dilution experiments demonstrate that this set is significantly more robust than one that amplifies across the intron, and sequencing of the intronic primer-binding region across several individuals shows that it is highly conserved. While our objective is to incorporate this primer set into an STR-based individualization kit, it may in the meantime prove useful in forensic or conservation studies
On Quantum Algorithms
Quantum computers use the quantum interference of different computational
paths to enhance correct outcomes and suppress erroneous outcomes of
computations. In effect, they follow the same logical paradigm as
(multi-particle) interferometers. We show how most known quantum algorithms,
including quantum algorithms for factorising and counting, may be cast in this
manner. Quantum searching is described as inducing a desired relative phase
between two eigenvectors to yield constructive interference on the sought
elements and destructive interference on the remaining terms.Comment: 15 pages, 8 figure
European Option Pricing with Liquidity Shocks
We study the valuation and hedging problem of European options in a market
subject to liquidity shocks. Working within a Markovian regime-switching
setting, we model illiquidity as the inability to trade. To isolate the impact
of such liquidity constraints, we focus on the case where the market is
completely static in the illiquid regime. We then consider derivative pricing
using either equivalent martingale measures or exponential indifference
mechanisms. Our main results concern the analysis of the semi-linear coupled
HJB equation satisfied by the indifference price, as well as its asymptotics
when the probability of a liquidity shock is small. We then present several
numerical studies of the liquidity risk premia obtained in our models leading
to practical guidelines on how to adjust for liquidity risk in option valuation
and hedging.Comment: 25 pages, 6 figure
A CROSS-SECTION ANALYSIS OF INTRA-INDUSTRY TRADE IN THE U.S. PROCESSED FOOD AND BEVERAGE SECTORS
This paper analyzes the determinants of variation across industries in levels of intra-industry trade (IIT) for a sample of 36 U.S. processed food and beverage industries in 1987, previous studies of intra-industry trade having focused on industry characteristics in the manufacturing sectors. The determinants predicted by IIT theory are measures of product differentiation, economies of scale, and imperfect competition; the results of this analysis indicate that IIT variation across the food and beverage industries is positively related to product differentiation, U.S. total trade, similarity of tariff barriers among trade partners, and economies of scope, but negatively related to industry concentration.International Relations/Trade,
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