Surveillance of stored grain from the 1997 harvest in the United Kingdom for ochratoxin A

This survey examined 306 samples of farm-stored wheat, barley and oats as received at, or tested by, central grain depots in the UK. Samples were taken from lorries or from stored grain using the existing inhouse procedures used for quality checking and examined for ochratoxin A using a fully validated analytical HPLC method with a detection limit of 0.1 μg/kg. Ochratoxin A was detected in 21 % of the samples examined, with barley more frequently contaminated than wheat. Mean concentrations of ochratoxin A found for all samples were 0.69 μg/kg in barley, 0.29 μg/kg in wheat and 0.15 μg/kg in oats. The highest concentration found was 17.8 μg/kg in a barley feed although concentrations of 81 and 30 μg/kg were found in 'reject-grade' wheat samples whose results were excluded from the main survey. In summary, 2.7 and 0.3 % of samples exceeded concentrations of 5 and 10 μg/kg respectively. There appeared to be significant relationships between ochratoxin A concentrations and moisture content, storage time and geographical area. Although conditions at harvest in 1997 were quite variable countrywide and often wet, results were similar to those found in earlier surveys carried out in the UK.     

MLAS: Multiple level authentication scheme for VANETs

The vehicular ad hoc network (VANET) is an emerging type of network which enables vehicles on roads to inter-communicate for driving safety. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles. However, this raises the concern of security and privacy. Messages should be signed and verified before they are trusted while the real identity of vehicles should not be revealed, but traceable by authorized party. Existing solutions either rely too heavily on a tamper-proof hardware device, or do not have an effective message verification scheme. In this paper, we propose a multiple level authentication scheme which still makes use of tamper-proof devices but the strong assumption that a long-term system master secret is preloaded into all tamper-proof devices is removed. Instead the master secret can be updated if needed to increase the security level. On the other hand, messages sent by vehicles are classified into two types – regular messages and urgent messages. Regular messages can be verified by neighboring vehicles by means of Hash-based Message Authentication Code (HMAC) while urgent messages can only be verified with the aid of RSUs nearby by means of a conditional privacy-preserving authentication scheme. Through extensive simulation, we show that our multiple level authentication scheme is much more efficient that those RSU-aided authentication scheme as long as the proportion of urgent messages is less than 100%. The verification delay required can be up to 110 times smaller than other protocols. Our implementation shows that batch verification may not be as efficient as expected. In case without batch verification, the verification delay required by our scheme can even be up to 173 times smaller.     

Integrated Services over ATM/MAN-Based Personal Communication Networks

IEEE 802.6 metropolitan area networks (MANs) providean efficient architecture for supporting wirelesspersonal communication services (PCSs) overmetropolitan areas by interconnecting wireless basestations into personal communication networks (PCNs).They also serve as peripheral gathering networks totransport PCS traffic over a wide area broadbandintegrated services digital network employingasynchronous transfer mode (ATM), enabling integrationof PCNs in different cities into a global PCN. Bycombining the various access methods and employing adynamic bandwidth integration scheme, a MAN canfunction as a powerful distributed switch forintegrating different types of local traffic.Simulation results are presented to illustrate theadvantages of the integration scheme. To provideubiquitous PCS, we also propose a simplesuffix-dialing method for integrating telephone, fax,paging and email services over the ATM/MAN-based PCNsusing a single personal telecommunication number. Withthis method, the current practice of printing a longlist of phone numbers on one's business card will nolonger be necessary.     

Vitamins as Active Agents for Highly Emissive and Stable Nanostructured Halide Perovskite Inks and 3D Composites Fabricated by Additive Manufacturing

The use of non-toxic and low-cost vitamins like α-tocopherol (α-TCP, vitamin E) to improve the photophysical properties and stability of perovskite nanocrystals (PNCs), through post-synthetic ligand surface passivation, is demonstrated for the first time. Especially interesting is its effect on CsPbI₃ the most unstable inorganic PNC. Adding α-TCP produces that the photoluminescence quantum yield (PLQY) of freshly prepared and aged PNCs achieves values of ≈98% and 100%, respectively. After storing 2 months under ambient air and 60% relative humidity, PLQY is maintained at 85% and 67%, respectively. α-TCP restores the PL features of aged CsPbI₃ PNCs, and mediates the radiative recombination channels by reducing surface defects. In addition, the combination of α-TCP and PNCs facilitates the chemical formulation to prepare PNCs-acrylic polymer composites processable by additive manufacturing. This enables the development of complex shaped parts with improved luminescent features and long-term stability for 4 months, which is not possible for non-modified PNCs. A PLQY ≈92% is reached in the 3D printed polymer/PNC composite, the highest value obtained for a red-emitting composite solid until now as far as it is known. The passivation shell provided by α-TCP makes that PNCs inks do not suffer any degradation process avoiding the contact with the environment and preserve their properties after reacting with polar monomers during composite polymerization.     

Identifying FMRI model violations with lagrange multiplier tests

The standard modeling framework in functional magnetic resonance imaging (fMRI) is predicated on assumptions of linearity, time invariance and stationarity. These assumptions are rarely checked because doing so requires specialized software, although failure to do so can lead to bias and mistaken inference. Identifying model violations is an essential but largely neglected step in standard fMRI data analysis. Using Lagrange multiplier testing methods we have developed simple and efficient procedures for detecting model violations such as nonlinearity, nonstationarity and validity of the common double gamma specification for hemodynamic response. These procedures are computationally cheap and can easily be added to a conventional analysis. The test statistic is calculated at each voxel and displayed as a spatial anomaly map which shows regions where a model is violated. The methodology is illustrated with a large number of real data examples.     

Modeling and Verification of a Sentiment Analysis System Using Aspect-Oriented Petri Nets

An increasing number of social media and networking platforms have been widely used. People usually post the online comments to share their own opinions on the networking platforms with social media. Business companies are increasingly seeking effective ways to mine what people think and feel regarding their products and services. How to correctly understand the online customers’ reviews becomes an important issue. This study aims to propose a method with the aspect-oriented Petri nets (AOPN) to improve the examination correctness without changing any process and program. We collect those comments from the online reviews with Scrapy tools, perform sentiment analysis using SnowNLP, and examine the analysis results to improve the correctness. In this paper, we apply our method for a case of the online movie comments. The experimental results have shown that AOPN is helpful for the sentiment analysis and verifying its correctness.     

Fortification of maize flour based diets with blends of cashewnut meal,African locust bean meal and sesame oil meal

The relative efficacy of protein blends (Blends I , 2:1:1; II , 1:2:1; III , 1:1:2, IV , 3:1:0; V , 1:3:0; VI , 3:0:1; VII , 1:0:3; VIII , 0:3:1 and IX , 0:1:3 of cashewnut, African locust bean and Beninseed flours) as compared to some commercially available baby foods ( “Farlene”, “Cerelac”, “Farex” and “Cow and Gate” cereal food) in meeting the protein needs of weanling albino rats have been studied. Growth promoting ability of the different blends ranged between 0.75 and 4.73 g/day while those for the commercial foods were 2.64–4.59 g/day. The values of 4.73 and 4.61 g/day for blends I and II were the best, being comparable to those of 4.59 g/day for “Cow and Gate” Cereal food but superior to those of 3.41 and 2.64 g/day for “Farlene” and “Cerelac”. The protein efficiency ratio (PER), net protein retention (NPR), net protein utilisation (NPU) and biological value (BV) for blends I and II were respectively 3.6, 4.4, 72.4 and 75.9 and 3.11, 3.8, 69.1 and 72.4, compared with the values of 2.5, 3.3, 65.8 and 69.5; 4.80, 0.41, 85.8 and 90.1; 3.2, 4.0, 73.5 and 76.1 and 4.0, 4.8, 76.5 and 79.8 for “Farlene”, “Cerelac”, “Farex” and “Cow and Gate” cereal food respectively. The blends and commercial baby foods showed high true digestibility values between 94.9 and 98.1 %. The results are discussed in the light of balance and limitation of amino acids in the component oil seed meals.     

PFC控制器芯片内部剖析

获得接近1的功率因数（powerfactor）是目前电源供应商的目标,这需要在AC/DC前端采用PFC电路,将输出电压提高至高于最大交流线峰值,通常达385VDC.本文将阐释PFC控制器的内部模块示意图、结构模块之间的同步和链接,以及电流修整和保护电路功能.此外,还会给出实际波形和参数选择的参考。     

Securing Threshold Cryptosystems against Chosen Ciphertext Attack

For the most compelling applications of threshold cryptosystems, security against chosen cipher text attack is a requirement. However, prior to the results presented here, there appeared to be no practical threshold cryptosystems in the literature that were provably chosen ciphertext secure, even in the idealized random oracle model. The contribution of this paper is to present two very practical threshold cryptosystems, and to prove that they are secure against chosen ciphertext attack in the random oracle model. Not only are these protocols computationally very efficient, but they are also non-interactive, which means they can be easily run over an asynchronous communication network. Received November 2000 and revised September 2001 Online publication 11 March 2002