8,280 research outputs found
Performance Analysis of a Low-Interference N-Continuous OFDM Scheme
This paper investigates two issues of power spectrum density (PSD) and bit
error rate (BER) of an N-continuous orthogonal frequency division multiplexing
(NC-OFDM) aided low-interference time-domain scheme, when the smooth signal is
designed by the linear combination of basis signals truncated by a window.
Based on the relationship between the continuity and sidelobe decaying, the PSD
performance is first analyzed and compared, in terms of the highest derivative
order (HDO) N and the length of the smooth signal L. Since the high-order
derivative of the truncation window has the finite continuity, the N-continuous
signal has two finite continuities, which may have different continuous
derivative orders. In this case, we develop a close PSD expression by
introducing another smooth signal, which is also linearly combined by other
basis signals, to explain the sidelobe decaying related to N and L. Then, in
the context of BER, considering the multipath Rayleigh fading channel, based on
the effect of the delayed tail of the smooth signal to the received signal, we
provide a procedure for calculating the BER expressed in the form of an
asymptotic summation.Comment: 7 pages, 6 figure
Rejoinder: Quantifying the Fraction of Missing Information for Hypothesis Testing in Statistical and Genetic Studies
Rejoinder to "Quantifying the Fraction of Missing Information for Hypothesis
Testing in Statistical and Genetic Studies" [arXiv:1102.2774]Comment: Published in at http://dx.doi.org/10.1214/08-STS244REJ the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Quantifying the Fraction of Missing Information for Hypothesis Testing in Statistical and Genetic Studies
Many practical studies rely on hypothesis testing procedures applied to data
sets with missing information. An important part of the analysis is to
determine the impact of the missing data on the performance of the test, and
this can be done by properly quantifying the relative (to complete data) amount
of available information. The problem is directly motivated by applications to
studies, such as linkage analyses and haplotype-based association projects,
designed to identify genetic contributions to complex diseases. In the genetic
studies the relative information measures are needed for the experimental
design, technology comparison, interpretation of the data, and for
understanding the behavior of some of the inference tools. The central
difficulties in constructing such information measures arise from the multiple,
and sometimes conflicting, aims in practice. For large samples, we show that a
satisfactory, likelihood-based general solution exists by using appropriate
forms of the relative Kullback--Leibler information, and that the proposed
measures are computationally inexpensive given the maximized likelihoods with
the observed data. Two measures are introduced, under the null and alternative
hypothesis respectively. We exemplify the measures on data coming from mapping
studies on the inflammatory bowel disease and diabetes. For small-sample
problems, which appear rather frequently in practice and sometimes in disguised
forms (e.g., measuring individual contributions to a large study), the robust
Bayesian approach holds great promise, though the choice of a general-purpose
"default prior" is a very challenging problem.Comment: Published in at http://dx.doi.org/10.1214/07-STS244 the Statistical
Science (http://www.imstat.org/sts/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Novel Delivery Systems of Nisin to Enhance Long-term Efficacy against Foodborne Pathogen Listeria monocytogenes
Novel intervention strategies such as food grade antimicrobials are used to enhance food safety. Nisin is a widely used naturally occurring antimicrobial effective against many pathogenic and spoilage microorganisms. However, its antimicrobial efficacy in food matrices is much reduced because of interactions with food components. Novel delivery systems may overcome this problem by protecting nisin in capsules and releasing it in a controlled manner. The overall goal of this research was to develop delivery systems of nisin to improve its long-term antimicrobial effectiveness. The first objective was to develop a low-cost method to extract nisin from a commercial preparation containing ~2.5% nisin. The best extraction yield was observed at 6 mg solids/mL 50% v/v ethanol. The nisin extract, after adjusting to 70% v/v ethanol, was dissolved with 2% zein (corn prolamins) and different amounts of Tween 20, glycerol, and thymol (another naturally occurring antimicrobial) for spray drying, a practical encapsulation method. Spray-dried capsules were characterized for release profiles of nisin at different pH conditions. Spray drying inlet temperature was first studied at 75 to 120°C, and the greatest sustained release of nisin was observed for capsules produced at 105°C, which was used in rest of this study. The impacts of Tween 20 and glycerol supplemented in spray-drying formulations were studied next. Addition of either 0.05% Tween 20 or glycerol in the spray-drying solution reduced the burst release of nisin at pH 6.0. Capsules with a higher amount of Tween 20 showed more complete release of nisin at pH 8.0, while glycerol had no apparent impact. The most sustained release of nisin at pH 6.0 was observed for capsules produced with both thymol and glycerol. Various capsules were then studied for their ability to inhibit the growth of Listeria monocytogenes at pH 6.0 during incubation at 30°C. Un-encapsulated nisin and thymol showed inhibition only for 12 h, while capsules with nisin and thymol containing either low or medium level of glycerol inhibited L. monocytogenes for \u3e96 h. Our antimicrobial delivery systems, based on food grade ingredients and practical processes, have potential for practical application to enhance microbial safety and extend the shelf-life of foods
The Design and Implementation of Mutual-Help Teaching System Based on Multimedia Network
AbstractWith the continuous increase in broadband users of China, the development of information, whose core is the Internet technology, laid a solid foundation for the implementation of in China. Network teaching, as a supplementary means inside and outside class, is increasingly being favored by the popular majority. In order to meet the new era of distance education, we need to develop a network teaching system, which allows the problems raised by users to be resolved quickly on this system. The communication system, including network teaching inside and outside the school, will be established and used in many fields, such as course development, online examination, homework management and teaching resource management
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