447 research outputs found
Berry effect in acoustical polarization transport in phononic crystals
We derive the semiclassical equations of motion of a transverse acoustical
wave packet propagating in a phononic crystal subject to slowly varying
perturbations. The formalism gives rise to Berry effect terms in the equations
of motion, manifested as the Rytov polarization rotation law and the
polarization-dependent Hall effect. We show that the formalism is also
applicable to the case of non-periodic inhomogeneous media, yielding explicit
expressions for the Berry effect terms.Comment: To appear in JETP Let
Solid-state laser system for laser cooling of Sodium
We demonstrate a frequency-stabilized, all-solid laser source at 589 nm with
up to 800 mW output power. The laser relies on sum-frequency generation from
two laser sources at 1064 nm and 1319 nm through a PPKTP crystal in a
doubly-resonant cavity. We obtain conversion efficiency as high as 2 W/W^2
after optimization of the cavity parameters. The output wavelength is tunable
over 60 GHz, which is sufficient to lock on the Sodium D2 line. The robustness,
beam quality, spectral narrowness and tunability of our source make it an
alternative to dye lasers for atomic physics experiments with Sodium atoms
An all-solid-state laser source at 671 nm for cold atom experiments with lithium
We present an all solid-state narrow line-width laser source emitting
output power at delivered in a
diffraction-limited beam. The \linebreak source is based on a
fre-quency-doubled diode-end-linebreak pumped ring laser operating on the
transition in Nd:YVO. By using
periodically-poled po-tassium titanyl phosphate (ppKTP) in an external build-up
cavity, doubling efficiencies of up to 86% are obtained. Tunability of the
source over is accomplished. We demonstrate the suitability of
this robust frequency-stabilized light source for laser cooling of lithium
atoms. Finally a simplified design based on intra-cavity doubling is described
and first results are presented
A microsatellite marker for yellow rust resistance in wheat
Bulk segregant analysis (BSA) was used to identify molecular markers associated with yellow rust disease resistance in wheat (Triticum aestivum L.). DNAs isolated from the selected yellow rust tolerant and susceptible F-2 individuals derived from a cross between yellow rust resistant and susceptible wheat genotypes were used to established a "tolerant" and a "susceptible" DNA pool. The BSA was then performed on these DNA pools using 230 markers that were previously mapped onto the individual wheat chromosomes. One of the SSR markers (Xgwm382) located on chromosome group 2 (A, B, D genomes) was present in the resistant parent and the resistant bulk but not in the susceptible parent and the susceptible bulk, suggesting that this marker is linked to a yellow rust resistance gene. The presence of Xgwm382 was also tested in 108 additional wheat genotypes differing in yellow rust resistance. This analysis showed that 81% of the wheat genotypes known to be yellow rust resistant had the Xgwm382 marker, further suggesting that the presence of this marker correlates with yellow rust resistance in diverse wheat germplasm. Therefore, Xgwm382 could be useful for marker assisted selection of yellow rust resistances genotypes in wheat breeding programs
Prevalence and outcomes of atrial fibrillation in older people living in care homes in Wales:a routine data linkage study 2003-2018
OBJECTIVE: To determine atrial fibrillation (AF) prevalence and temporal trends, and examine associations between AF and risk of adverse health outcomes in older care home residents. METHODS: Retrospective cohort study using anonymised linked data from the Secure Anonymised Information Linkage Databank on CARE home residents in Wales with AF (SAIL CARE-AF) between 2003 and 2018. Fine-Gray competing risk models were used to estimate the risk of health outcomes with mortality as a competing risk. Cox regression analyses were used to estimate the risk of mortality. RESULTS: There were 86,602 older care home residents (median age 86.0 years [interquartile range 80.8–90.6]) who entered a care home between 2003 and 2018. When the pre-care home entry data extraction was standardised, the overall prevalence of AF was 17.4% (95% confidence interval 17.1–17.8) between 2010 and 2018. There was no significant change in the age- and sex-standardised prevalence of AF from 16.8% (15.9–17.9) in 2010 to 17.0% (16.1–18.0) in 2018. Residents with AF had a significantly higher risk of cardiovascular mortality (adjusted hazard ratio [HR] 1.27 [1.17–1.37], P < 0.001), all-cause mortality (adjusted HR 1.14 [1.11–1.17], P < 0.001), ischaemic stroke (adjusted sub-distribution HR 1.55 [1.36–1.76], P < 0.001) and cardiovascular hospitalisation (adjusted sub-distribution HR 1.28 [1.22–1.34], P < 0.001). CONCLUSIONS: Older care home residents with AF have an increased risk of adverse health outcomes, even when higher mortality rates and other confounders are accounted for. This re-iterates the need for appropriate oral anticoagulant prescription and optimal management of cardiovascular co-morbidities, irrespective of frailty status and predicted life expectancy
Latency reduction by dynamic channel estimator selection in C-RAN networks using fuzzy logic
Due to a dramatic increase in the number of
mobile users, operators are forced to expand their networks
accordingly. Cloud Radio Access Network (C-RAN) was
introduced to tackle the problems of the current generation of
mobile networks and to support future 5G networks. However,
many challenges have arisen through the centralised structure of
C-RAN. The accuracy of the channel state information
acquisition in the C-RAN for large numbers of remote radio
heads and user equipment is one of the main challenges in this
architecture. In order to minimize the time required to acquire
the channel information in C-RAN and to reduce the end-to-end
latency, in this paper a dynamic channel estimator selection
algorithm is proposed. The idea is to assign different channel
estimation algorithms to the users of mobile networks based on
their link status (particularly the SNR threshold). For the
purpose of automatic and adaptive selection to channel
estimators, a fuzzy logic algorithm is employed as a decision
maker to select the best SNR threshold by utilising the bit error
rate measurements. The results demonstrate a reduction in the
estimation time with low loss in data throughput. It is also
observed that the outcome of the proposed algorithm increases at
high SNR values
Modelling Temperature Variation of Mushroom Growing Hall Using Artificial Neural Networks
The recent developments of computer and electronic systems have made the use
of intelligent systems for the automation of agricultural industries. In this
study, the temperature variation of the mushroom growing room was modeled by
multi-layered perceptron and radial basis function networks based on
independent parameters including ambient temperature, water temperature, fresh
air and circulation air dampers, and water tap. According to the obtained
results from the networks, the best network for MLP was in the second
repetition with 12 neurons in the hidden layer and in 20 neurons in the hidden
layer for radial basis function network. The obtained results from comparative
parameters for two networks showed the highest correlation coefficient (0.966),
the lowest root mean square error (RMSE) (0.787) and the lowest mean absolute
error (MAE) (0.02746) for radial basis function. Therefore, the neural network
with radial basis function was selected as a predictor of the behavior of the
system for the temperature of mushroom growing halls controlling system
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