bluuebunny/crossref_metadata_2025 huggingface dataset:
Architecture and networking issues in satellite systems for personal communications
Authors: Ananasso Fulvio , Carosi Marco
Published: July 2007

The paper expands on some specific aspects of personal communications via satellite, often–although not necessarily–envisaging extensive use of ‘small’ satellites, using orbits not necessarily coinciding with the geostationary one (36,000 km), but rather at 1000–11,000 km altitude. One key point to be borne in mind is the issue of internetworking between satellite and terrestrial systems. Network integration should be carefully implemented in order to comply with ITU future public land mobile telecommunication systems (FPLMTS) requirements, also accepted in the European Telecommunication Standards Institute (ETSI) universal mobile telecommunication systems (UMTS). In addition to some insight into the technology of small satellites and associated orbits, architectures and networking aspects of most relevant systems providing personal communication services (PCS) are addressed in some detail, and potential applications highlighted. Frequency spectrum allocation is addressed in the light of the 1992 World Administrative Radio Conference (WARC‐92), taking into account also multiple access problems and regulatory issues such as Federal Communications Commission (FCC) licensing and spectrum sharing debates. Some remarks on critical technologies and cost conclude the paper.
Influences of external digital environment, markets and terminal price elasticity on personal satellite systems
Authors: Brandon William T.
Published: July 2007

Although there is no doubt about the feasibility of personal communications via small satellites in low earth orbit, there is considerable uncertainty about the size of the market, whether the specific applications will be business or personal in context, about the market relationship between voice services and data services, and the implications for system design of any information that might be developed on these questions.

This paper will develop the concept that the key to understanding low orbit small satellite communications systems is the message delivery time requirement of markets and that the data services market has a widely varying range of acceptable data delivery times. We estimate the distribution of data delivery time versus population of users on a global basis.

A second concept to be developed in this paper is that low orbit satellites are in some respects matched to global data delivery applications because of the daylight time zones and natural delays they impose.

Using the estimated market size versus message delivery time, we show that there is a significant design implication for the space segment in terms of the number of satellites, the orbit period, and the use of crosslinks. It will be further shown that the difference in complexity of data and voice services with respect to cost argues for the rapid emergence and success of data services.

Finally, we will show that a preferred terminal architecture may be an accessory or applique for a personal computer, rather than a small dedicated satellite terminal, based on the extant population of personal computers. A review of the planned terminal architectures of emerging systems reveals that using a personal computer as the basis for a terminal has not yet received wide interest. In particular, the new laptop smaller computers may be the natural catalyst for personal satellite data services in facilitating the terminal.
Interference between satellite systems in non‐geostationary orbits
Authors: Nelson Robert A. , Pritchard W. L.
Published: July 2007

Satellites are considered in arbitrary orbits, and interference between them and other satellites or earth‐stations is calculated. The composite interference from a complete system is found by summing over the set of visible satellites. One starts with the Keplerian orbital parameters and assumed antenna patterns and transmitter characteristics. Using classical orbital mechanics and a series of co‐ordinate transformations, one determines the location of any satellite in the frame of reference of any other satellite or earth‐station. Conventional interference methods are then used to find the result.
An advanced satellite communication system with on‐board fast packet switching capabilities
Authors: Del Re Enrico , Fantacci Romano
Published: July 2007

This paper is focused on a satellite communication system having on‐board fast packet switching capabilities. Different alternatives for the up‐link access technique and for the architecture of the onboard switching fabric are considered. In particular an efficient time division multiple access technique with slots assigned on demand and a novel switching approach are proposed. Performances in terms of mean access delay and mean on‐board switching delay are derived by analytical approaches and computer simulations.
Implementation of adaptive modulation as A fade countermeasure
Authors: Filip Miodrag , Vilar Enric
Published: July 2007

Three key problem areas associated with implementation of the concept of adaptive modulation as a fade countermeasure in a practical VSAT system are addressed in this paper. First, the heart of such a system, an adaptive modem, is described; such a device should be able to support a number of different modulation schemes, independently for modulation and demodulation. It is shown how an adaptive modulator can be built around a VLSI numerically controlled oscillator and that an adaptive demodulator is feasible once the universal carrier tracking loop is implemented with use of digital signal processing. As regards system operation, a data transfer scenario is described which highlights that it is important to expand the set of commands and responses of the data link control protocol in order to cater for the new abilities of the system. Finally, the article describes a computer simulation of system performance evaluation under dynamic rain fading propagation conditions and applied to a Ka band link. The results confirm earlier theoretical work and show great advantage over systems using fixed modulation schemes and fixed link propagation budget margins.
An architecture design approach for large satellite networks
Authors: Cotner C. , Inukai T.
Published: July 2007

Designing a world‐wide satellite network that consists of hundreds of user sites and thousands of circuit connections is a complex problem, which involves selecting a set of candidate satellites and satellite beams/frequency bands from among numerous existing and planned satellites, evaluation of circuit connectivity, earth‐station compatibility and sizing, and estimating transponder loading. The design process may also require assessment of the impact of a different set of satellites and modified user traffic requirements on the space segment, the earth‐station types and quantity, and the total system cost. Although a conventional design approach based on link‐by‐link and site‐by‐site analysis provides accurate results, it is time‐consuming and impractical for developing high‐level network architectures in a time‐constrained environment. A design technique is proposed which employs a set of rules for satellite network design, in combination with extensive databases of satellite parameters, earth‐station parameters and user traffic requirements, to synthesize a network architecture. The technique is particularly useful for performing high‐level trade‐offs among alternative architectures in terms of space segment requirements, the number and type of earth‐stations and overall system cost. Once the desired architecture has been selected, a detailed design may be developed using conventional methods.
Performance of A prioritized on‐board baseband switch for A multiservice multibeam satellite
Authors: Bohm S. , Elhakeem A. K. , Murthy K. M. S. , Hachicha M.
Published: July 2007

In this paper, we study the performance of a prioritized on‐board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, file transfer and interactive data. The prioritized switch uses both input and output buffering, switch speed‐up as well as a two‐phase head‐of‐line resolution algorithm, in order to reduce the buffer loss while maintaining acceptable user delays. The minimum required buffer capacity and switch speed‐up for each service in a prioritized environment are found under uniform traffic conditions. It is shown that under uniform traffic conditions, only minimal buffering and switch speed‐up are needed even for the lowest priority users. The performance dependence on the switch size is also substantially reduced with head of line resolution and buffering even in a prioritized environment.
Performance of the GLONASS P‐code at L1 and L2 frequencies
Authors: Riley Stuart , Daly Peter
Published: July 2007

The transmission of satellite signals at two widely spaced frequencies allows correction of the ionospheric delay. Both GPS and GLONASS transmit such signals, and to date there have been no published dual frequency GLONASS studies. This paper shows the fundamental accuracy of the Leeds University multichannel GPS/GLONASS receiver. Details are then given of the processing methods that have been used to obtain the ionospheric group delay using GLONASS L1 and L2 P‐code measurements. Examples of the measured delay are provided and compared with the GPS model. Navigation results are shown using the P‐code phase at L1 only and with a combination of the L1 and L2 measurements. An analysis of the accuracy of the P‐code pseudorange and navigation capability is presented.
Digital sound broadcasting: Satellites or Terrestrial Networks?
Authors: Lemaire Jean
Published: July 2007

When European laboratories decided to develop a digital sound broadcasting system (DSB), they specified three main conditions to fulfil:

quality improvement up to the level of ‘CD’ sound, even in difficult reception conditions (mobile vehicles, etc)

additional significant digital data transmissions in order to transform sound broadcasting into a really new service

the possibility of a common system for satellite and terrestrial transmissions.

It is on these bases that the European project ‘Eureka 147’ defined the system called DAB (digital audio broadcasting). In 1992, the ITU Conference WARC 92 allocated 40 MHz to DSB in the L‐band in the configuration of complementary terrestrial and satellite networks; nevertheless, the present state of technical possibilities makes such mixed networks almost unfeasible and the lack of available spectrum in VHF bands led a significant number of countries to envisage L‐band for T‐DAB. The situation could turn to a competition between terrestrial and satellite networks, especially because the bandwidth in L‐band is not that large!

France belongs to the countries facing this problem. L‐band alone is intended to be used by T‐DAB, and broadcasters taking part in the work of ‘Club DAB’ estimated that 20 MHz would be a minimum to ensure the success of T‐DAB introduction. It is half of the DSB band. Splitting this band into two parts has already been decided by CEPT, but in the proportion of 1/3 for T‐DAB. This organization intends to arrange a European planning meeting for T‐DAB in July 1995, and, shortly after, several countries are ready to start the implementation of the terrestrial networks. At the same time, international broadcasters wonder whether satellite transmission could present an alternative to HF.
In‐orbit testing of TDMA occupied channels
Authors: Kasstan B. , Bosowski M. , Horton M.
Published: July 2007

The expected introduction of new TDMA earth‐stations in the EUTELSAT network with a lower diameter antenna, together with the need to ensure the high quality of services are the two principal reasons why regular review of the performance trend of TDMA links is becoming so vital. Such a review will allow overall optimization of the EUTELSAT TDMA system by ensuring that the transponders are operated at their specified points, and will make it possible to be prepared in advance in the event of a transponder gain drop to reconfigure the system with no loss of traffic.

To implement these tests, EUTELSAT at its IOT facilities near Paris has installed a burst mode saturation analyser' (BMSA) developed by Hollis Electronics Company. The BMSA has been specially designed as a stand‐alone test system for testing TDMA channels in a burst mode without interrupting the operational traffic.

This paper describes how the BMSA operates and in particular how the system self synchronizes in order to position the BMSA test burst correctly in the frame, and how the burst is allowed to vary in amplitude in order to characterize the channel under test. This paper also discusses how the BMSA is interfaced to the host IOT station and how the tight measurement accuracy in terms of absolute transmit e.i.r.p. and spacecraft IPFD have been met.

The paper concludes by comparing results obtained by classical CW test methods with this new burst method. The conclusions also discuss the limitations of the system and suggest possible improvements.
Performance analysis of integrated‐services load‐adaptive/TDMA satellite networks
Authors: Rubin Izhak , Chang Kirk K. , Forcina Gianpero
Published: July 2007

A load‐adaptive/TDMA multiple‐access communications system which serves to interconnect broad‐band multimedia packet streams is considered. In particular, the use of a satellite backbone communications link whose channels are dynamically assigned to network stations is investigated. Each station supports packetized voice and data message streams. Incoming streams to a station are statistically multiplexed by the station across the backbone channels currently allocated to this station. To enhance the multiplexing process, a variable bit‐rate packet‐voice encoding scheme is also employed. Stations periodically issue requests for backbone channel allocations, based upon their estimated loading status. We introduce two distinct multiple‐access algorithms for allocating the shared backbone channels to the stations. We develop analytical methods for the analysis and design of such integrated multiplexing/multiple‐access networks. Performance measures include voice and data packet delays and packet blocking probabilities. Voice stream performance is also characterized by the average number of bits per sample used by the voice encoding scheme. The effects of the propagation delay across the backbone link are especially demonstrated. Also illustrated are the performance improvements attained due to the use of the load‐adaptive/TDMA scheme. Under the example of the ’all‐voice’ traffic loading, an LA/TDMA scheme exhibits no obvious performance improvement over a fix‐assigned scheme. However, as the burstiness of the traffic loading increases in the example of the ’data‐voice’ traffic loading, a significant amount of improvement (36 per cent bandwidth savings) is realized by a LA/TDMA scheme.
A computationally efficient method of timing and phase estimation in TDMA systems using a preamble sequence
Authors: Bolding Gerald , Cowley William G.
Published: July 2007

Optimum and near optimum methods of burst parameter estimation based on the discrete Fourier transform are presented. The methods are applicable to single sample per symbol demodulators when the burst preamble is chosen to be a discrete frequency component at one quarter of the symbol rate. The proposed methods do not require the squaring of the signal, and hence avoid the loss associated with squaring the noise components. The optimum method is shown to reach the Cramer‐Rao bound for symbol timing and carrier phase estimation for the chosen preamble, whereas the more computationally efficient method shows a loss of 1.0dB and yields information regarding the timing offset only. The performances of the two methods in the presence of carrier frequency offset and additive white Gaussian noise are analysed, and implementations are given together with a comparison of the respective computational complexities.
Distributed access algorithms for portable meshed vsat networks
Authors: Piñtar F. J. Ruiz , Fern Campo A. Ández Del , Nieto C. Miguel , Sisó L. Vidaller
Published: July 2007

In recent years technological evolution has made it possible to develop portable meshed VSAT networks (PMVN). Among the distinguishing features of this satellite network family we can cite the following: portable terminals, direct connectivity is allowed between any pair of network nodes (meshed topology), the network may comprise a high number of terminals, the network is intended to offer low rate voice and data communication services. For this satellite network family, the most widely used technique of resource allocation is centralized allocation. But in any network with a high number of nodes, the dependence on a single resource is a potential bottleneck of the network, in terms of flexibility, reliability and scalability of costs. In order to avoid this drawback, two distributed access algorithms are proposed in this paper. Both algorithms are based on carrier sensing (CS). In order to evaluate their performance, a model for PMVNs is proposed. This model is used to study the behaviour of the conventional access technique (central allocation) and the proposed distributed algorithms. We conclude that the use of the proposed distributed algorithms is feasible with present technology, with a performance comparable to that of the central allocation algorithm, but with the advantages associated with distributed algorithms concerning flexibility, reliability and cost.
Clustering of membrane proteins in the pre‐stimulation stage is required for signal transduction: a computer analysis
Authors: Kobayashi Hiroshi , Azuma Ryuzo , Konagaya Akihiko
Published: July 2007

The physiological significance of membrane protein clustering for signal transduction was examined theoretically using a Monte Carlo computer simulation. Simulation results revealed that pre‐stimulation clustering of membrane proteins enhanced signal transduction. Membrane protein clustering induced by the binding of external stimuli provided no kinetic advantage in terms of formation rate or maximum quantity of active membrane receptor complexes. These data suggested that membrane proteins associate weakly in the clustering areas of non‐stimulated cells, and that their association is strengthened upon binding of extracellular stimuli to the membrane receptor. Additionally, the number of cytosolic proteins recruited to membrane receptor complexes was not increased by the membrane complex clustering, except when cytosolic signal proteins were localized to a narrow area such as a tunnel that ran from the membrane cluster to the nucleus. Simulations were carried out on a conventional personal computer under Windows XP or 2000 operating systems. Since neither special computing hardware nor special training is required, our simulation procedure could be easily adapted for kinetic analysis of any signal transduction pathway.
A Method for Reproducibly Preparing Synthetic Nanopores for Resistive‐Pulse Biosensors
Authors: Wharton John E. , Jin Pu , Sexton Lindsay T. , Horne Lloyd P. , Sherrill Stefanie A. , Mino Warren K. , Martin Charles R.
Published: July 2007

There is increasing interest in using nanopores in synthetic membranes as resistive‐pulse sensors for biomedical analytes. Analytes detected with prototype artificial‐nanopore biosensors include drugs, DNA, proteins, and viruses. This field is, however, currently in its infancy. A key question that must be addressed in order for such sensors to progress from an interesting laboratory experiment to practical devices is: Can the artificial‐nanopore sensing element be reproducibly prepared? We have been evaluating sensors that employ a conically shaped nanopore prepared by the track‐etch method as the sensor element. We describe here a new two‐step pore‐etching procedure that allows for good reproducibility in nanopore fabrication. In addition, we describe a simple mathematical model that allows us to predict the characteristics of the pore produced given the experimental parameters of the two‐step etch. This method and model constitute important steps toward developing practical, real‐world, artificial‐nanopore biosensors.
Thermal polymerization of unsaturated fatty esters normal methyl linoleate
Authors: Paschke R. F. , Wheeler D. H.
Published: July 2007

Debromination methyl linoleate has been polymerized at 290° and 300° for varying periods, and analysis has been made for monomer, dimer, trimer, normal, and conjugated linoleate.

The disappearance of normal linoleate follows a first order reaction rate with values of K=0.10 hr.−1 at 300° and 0.05 hr.−1 at 290°.

Polymerization of mixtures of normal and conjugated linoleate indicate that dimer may be formed by their reaction with each other.

The value for K, the first order reaction velocity constant for disappearance of normal linoleate, decreases to a limiting value on dilution with methyl stearate. This limiting value is about one‐fourth that obtained on undiluted linoleate.

The above facts are qualitatively explained by assuming that the mechanism of dimerization of normal linoleate is extensively: N»C relatively slow N+C→D relatively rapid.
The aldehydes produced during the autoxidation of cottonseed oil
Authors: Swift C. E. , O'Connor R. T. , Brown L. E. , Dollear F. G.
Published: July 2007

Spectrophotometric evidence was obtained that Δ2 and Δ2:4 aldehydes are produced during the autoxidation of cottonseed oil.

The unsaturated carbonyls were converted into semicarbazones and 2,4‐dinitrophenylhydrazones whose characteristics indicated that the oxidation of cottonseed oil produces Δ2:4‐decadienal, Δ2‐octenal, and hexanal.

Although the exact mechanism of their formation has not been established, these aldehydes are believed to result from the decomposition of the isomeric hydroperoxides of linoleic acid, the principal fatty acid constituent of cottonseed oil.
Application of spectrophotometric methods to the determination of glycerine color
Authors: Miner C. S. , Weil C. M.
Published: July 2007

A method has been developed by which spectrophotometrically measured glycerine color can be expressed in terms of Lovibond units. The yellow and red color values are determined, by means of two statistically derived linear relationships, from optical density measurements at 440 mμ and 520 mμ, respectively. The conversion from spectrophotometric data to Lovibond color units may be done graphically and the results are at least as reliable as the results of repeated visual measurements.
Analyses of mixtures of t,tΔ9,11‐ and t,tΔ10,12‐linoleic acids by X‐ray diffraction patterns and solidification points
Authors: Witnauer Lee P. , Nichols Peter L. , Senti Frederic R.
Published: July 2007

X‐ray diffraction and solidification point data are reported for t,tΔ9,11‐ and t,tΔ10,12‐linoleic acids and their mixtures. The long spacing of the Δ9,11‐isomer was 47.95 Å whereas that of the Δ10,12‐isomer was 44.09 Å. X‐ray diffraction patterns of binary mixtures showed the characteristic pattern of each isomer if the mixture contained not less than 25% of the t,tΔ10,12‐isomer or not less than 5% of the t,tΔ9,11‐isomer. Outside these composition limits only the pattern of the predominant isomer appeared, and solidification point data were used to define the composition. The solidification point in conjunction with the X‐ray data defined the composition of any mixture to ±3%.
Oxidation of various lipid substrates with unfractionated soybean and wheat lipoxidase
Authors: Guss P. L. , Richardson T. , Stahmann M. A.
Published: July 2007

Quantitative determinations of lipoxidase in wheat were made on five milling fractions from four wheat varieties, including two hard red winter and two hard red spring wheats. Lipoxidase content decreased with increasing refinement and was lowest in the flour fraction. In general, the mill fractions from spring wheats exhibited slightly higher lipoxidase content than the corresponding mill fractions from winter wheats.

Aqueous extracts from soybeans (variety Hawkeye) and wheat (variety Selkirk, break shorts fraction) were adjusted in concentration so that the lipoxidase activity with respect to linoleic acid was approximately the same. The diluted extracts were then tested for their ability to oxidize other lipid substrates with the necessary 1,4 pentadiene system. Soybean lipoxidase was far more reactive toward methyl linoleate and trilinolein than wheat lipoxidase. Mono‐ and dilinolein were relatively unreactive in both systems although dilinolein was a better substrate in the soybean system than in the wheat. Neither system oxidized highly unsaturated digalactosyl diglycerides alone. However the soybean extract oxidized this substrate to a small extent in the presence of catalytic amounts of linoleic acid while, under identical conditions, the wheat extract remained inactive.

Polyacrylamide gel electrophoresis of the aqueous extracts of soybeans and wheat‐milling fractions coupled with a staining procedure specifically for lipoxidase indicated three to four isoenzyme bands in the soybeans and two to four isoenzyme bands in the wheat‐milling fractions. Isoenzymes may be responsible for differences in enzymatic activity on various substrates.
Eleostearic acid derivatives. I. Reactions at the carboxyl group
Authors: Thames Shelby F. , Long J. S. , Smith O. D. , Jen S. J. , Evans J. M.
Published: July 2007

Nine C1 substituted derivatives of eleostearic acid have been prepared and characterized by elemental analyses and spectrophotometric data. The preparation of two additional derivatives is indicated by infrared spectroscopy, but difficulties in purification precluded elemental analysis data. Comments are made concerning conditions for product stability and reaction environment.
A study of eleostearic acid‐containing resins
Authors: Long J. S. , Thames Shelby F. , Smith Oliver W.
Published: July 2007

A variety of polyesters, polyurethanes, and sulfonyl‐polyurethanes containing eleostearic acid (ESA) have been prepared and evaluated. The film parameters under investigation usually included water absorption, tensile strength, elongation, density, permeability, and percentage of oxygen uptake.

The incorporation of ESA into polyester resin compositions results in such film properties as decreased water absorption, oxygen uptake, elongation, and permeability with a concemitant increase in tensile strength and density. Oxidativepolymerization of the polyesters containing ESA affords advantages in that their films show good tensile strength. Elongation is quite superior to that of the non‐oxidatively polymerized ESA polyesters.

As a result of the advantages gained by the incorporation of ESA into polyester resins, its use (or tung oil) is recommended in these and similar resin systems.
A review of methods for determining pesticide residues, contaminants and adulterants in fats and oils
Authors: Firestone David
Published: July 2007

Sensitive chromatographic methods are available for determining chlorinated pesticide residues and chick edema factor contaminants in fats and oils. Determination of chlorinated pesticide residues in fats and oils generally involves acetonitrile extraction, Florisil column cleanup, and analysis by electron capture gasliquid chromatography (ECGLC). However, other procedures are available including dimethyl sulfoxide extraction and sweep codistillation. Sensitive screening tests for chick edema factor involve alumina column fractionation of isolated unsaponifiable matter, sulfuric acid cleanup, and examination by ECGLC. Admixtures of animal and vegetable fats are detected by the gasliquid chromatography (GLC) of isolated sterols, and individual vegetable oils can be characterized by GLC analysis of the sterols as well as of the other unsaponiflable constituents.
Health Beliefs and Behaviors of Women Who Have Received Genetic Counseling For Breast Cancer
Authors: Rees Gwyneth , Gaff Clara , Young Mary‐Anne , Martin Paul R.
Published: July 2007

There are both genetic and behavioral risk factors for breast cancer, but the interaction between these factors is not clear. Little is known about the impact of receiving genetic risk information for breast cancer on behaviors such as diet and physical activity. Seven focus groups were conducted with 23 women who had recently received genetic counseling for breast cancer, in order to explore health beliefs and behaviors following genetic counseling. Findings revealed that there was much confusion and uncertainty about the associations between health behaviors and breast cancer risk, and participants reported that receiving genetic counseling had little impact on health protective behaviors. Further research is required to understand variation in response to genetic risk information, and to assess the impact of providing additional information regarding lifestyle factors.
INDIGENOUS MULTIPLICATION AND PRODUCTION PRACTICES FOR THE TUBER CROP PLECTRANTHUS EDULIS IN CHENCHA AND WOLAITA, SOUTHERN ETHIOPIA
Authors: TAYE MULUGETA , LOMMEN WILLEMIEN J. M. , STRUIK PAUL C.
Published: July 2007

Plectranthus edulis (syn. Coleus edulis) is a tuber-bearing labiate species cultivated in parts of southern Ethiopia. To learn about traditional cultural practices and their rationale, a survey was conducted among farmers from Chencha and Wolaita experienced in growing this crop. A pre-tested questionnaire was used to interview 48 family heads categorized into three wealth groups per site. Information was checked through group discussions and field observations. In Wolaita, poorer farmers cropped a larger portion of their land to P. edulis than richer farmers. Land was usually prepared for planting between January and April. In Wolaita, the crop was mostly grown in a furrow. In Chencha growing in patches and on flat land also occurred. Farmers mostly used a digging hoe for land preparation. Tuber pieces were planted about 5 cm deep. According to farmers, using tuber pieces resulted in more stems, more progeny tubers and higher yields than using whole tubers. Tubers were broken into pieces 0–1 day before planting. Tuber pieces were planted with sprouts or after desprouting. Crops were usually fertilized with manure, but in Wolaita sometimes also with compost. Applying fertilizer was thought to give more and bigger tubers. Earthing up took place 1–3 times (usually twice), to increase yield. Tipping was also done 1–3 times (usually once), to increase the number of stems. Based on the survey, an overview of the practices and their rationale is compiled for use in further research into this orphan crop.
THE ECONOMIC POTENTIAL AND FARMER PERCEPTIONS OF HERBACEOUS LEGUME FALLOWS IN GHANA
Authors: OBIRI BEATRICE DARKO , BRIGHT GEOFF , MCDONALD MORAG , JATANGO JOHN AYISI , COBBINA JOSEPH , SINCLAIR FERGUS
Published: July 2007

A technology for improving the productivity of short fallows using herbaceous legumes as cover crops was evaluated with farmers in the forest and savannah transition zones of Ghana. Legumes were relayed in maize 5–8 weeks after planting maize, depending on the legume species. An economic analysis of the technology compared with natural fallow over two cropping seasons (2001–2002) showed that the legume fallows were more profitable under the scenarios tested. Farmer assessment of the biological performance of the technology revealed the benefits of weed suppression and soil moisture conservation potential of the legume biomass as well as an improvement in the yield of the succeeding maize crop. However, farmers realized that planting legumes at close spacing and weeding before and after relaying are essential in the development of an appreciable biomass cover. The technology is suitable for farmers of all strata, in several major ecological zones of Ghana, and for planting on land with poorly secured tenure. However, at least two years of tenancy is required for the landless to derive some benefits from the legume fallow.
The electronic identity of inductive and capacitive plasmas
Authors: BURM K. T. A. L.
Published: July 2007

An electronic identity relation, relating capacitively coupled plasma sources to corresponding inductively coupled plasma sources, has been derived, starting from the Maxwell relations for matter and the characteristics of a capacitor and of an inductor. Furthermore, the breakdown conditions for both capacitively coupled plasmas and for inductively coupled plasmas as well as their optimal operation frequency ranges are discussed.
Force and velocity observers for the control of cooperative robots
Authors: Martínez-Rosas Juan C. , Arteaga Marco A.
Published: July 2007

In this paper, we design a position/force controller for cooperative robots during constrained motion. The proposed scheme is based on the knowledge of the manipulator dynamics and does not require measurements of link velocity or end-effector contact forces. A well-known velocity observer and the design of a force observer are used. The validity of the proposed method is verified by means of experimental results.
Lightweight family polymorphism
Authors: SAITO CHIERI , IGARASHI ATSUSHI , VIROLI MIRKO
Published: July 2007

Family polymorphism has been proposed for object-oriented languages as a solution to supporting reusable yet type-safe mutually recursive classes. A key idea of family polymorphism is the notion of families, which are used to group mutually recursive classes. In the original proposal, due to the design decision that families are represented by objects, dependent types had to be introduced, resulting in a rather complex type system. In this article, we propose a simpler solution oflightweightfamily polymorphism, based on the idea that families are represented by classes rather than by objects. This change makes the type system significantly simpler without losing much expressive power of the language. Moreover, “family-polymorphic” methods now take a form of parametric methods; thus, it is easy to apply method type argument inference as in Java 5.0. To rigorously show that our approach is safe, we formalize the set of language features on top of Featherweight Java and prove that the type system is sound. An algorithm for type inference for family-polymorphic method invocations is also formalized and proved to be correct. Finally, a formal translation by erasure to Featherweight Java is presented; it is proved to preserve typing and execution results, showing that our new language features can be implemented in Java by simply extending the compiler.
A duality between proof systems for cyclic term graphs
Authors: GRABMAYER CLEMENS
Published: July 2007

This paper presents a proof-theoretic observation about two kinds of proof systems for bisimilarity between cyclic term graphs.

First we consider proof systems for demonstrating that μ term specifications of cyclic term graphs have the same tree unwinding. We establish a close connection between adaptations for μ terms over a general first-order signature of the coinductive axiomatisation of recursive type equivalence by Brandt and Henglein (Brandt and Henglein 1998) and of a proof system by Ariola and Klop (Ariola and Klop 1995) for consistency checking. We show that there exists a simple duality by mirroring between derivations in the former system and formalised consistency checks, which are called ‘consistency unfoldings', in the latter. This result sheds additional light on the axiomatisation of Brandt and Henglein: it provides an alternative soundness proof for the adaptation considered here.

We then outline an analogous duality result that holds for a pair of similar proof systems for proving that equational specifications of cyclic term graphs are bisimilar.
Determinants of mild-to-moderate malnutrition in preschoolers in an urban area of Northeastern Brazil: a hierarchical approach
Authors: Oliveira Assis Ana Marlúcia , Lima Barreto Maurício , Magalhães de Oliveira Lucivalda Pereira , de Oliveira Valterlinda Alves , da Silva Prado Matildes , da Silva Gomes Gecynalda Soares , Conceição Pinheiro Sandra Maria , dos Santos Nedja Silva , Ribeiro da Silva Rita de Cássia , Ramos Sampaio Lilian , Pacheco Santos Leonor Maria
Published: July 2007

Objective

To investigate the determinants of mild-to-moderate malnutrition in preschoolers.

Design

Cross-sectional study conducted in October and November 1996, with a representative sample of 1740 children less than 5 years old from the city of Salvador, situated in the Brazilian Northeastern region. Socio-economic and dietary data were collected through a structured questionnaire. Anthropometric measures were performed in duplicate and data analysis was based upon the hierarchical model approach. Logistic regression analysis was used to estimate the prevalence ratio and to identify the determinants of mild-to-moderate deficits in weight-for-age and height-for-age Z-scores.

Results

Family monthly income under US$67.00 per capita and family headed by a woman were the main basic determinants of mild-to-moderate weight-for-age and height-for-age deficits in the studied children. Household agglomeration, an underlying determinant, was associated with weight-for-age and height-for-age deficits. Among the immediate determinants, age above 6 months and dietary caloric availability in the lowest tertile (<930 kcal day−1) were also associated with weight-for-age deficits. In addition to these, hospitalisation in the 12 months preceding the interview was shown to be a predictor of mild-to-moderate weight-for-age and height-for-age deficits.

Conclusion

Adverse social and economic factors interact with family environmental factors to define food consumption and morbidity patterns that culminate in a high prevalence of mild-to-moderate malnutrition. The strengthening and restructuring of nutrition and healthcare actions, the definition of public policies that improve family income, and the adequate insertion of women in the labour market are possible strategies to reduce mild-to-moderate malnutrition and to sustain the decline already observed in severe malnutrition.
Increasing fruit and vegetable consumption: success of the Western Australian Go for 2&5®campaign
Authors: Pollard Christina M , Miller Margaret R , Daly Alison M , Crouchley Kathy E , O’Donoghue Kathy J , Lang Anthea J , Binns Colin W
Published: July 2007

Objective

The Western Australian Health Department’s Go for 2&5® campaign aimed to increase adults’ awareness of the need to eat more fruit and vegetables and encourage increased consumption of one serving over five years.

Design

The multi-strategy fruit and vegetable social marketing campaign, conducted from 2002 to 2005, included mass media advertising (television, radio, press and point-of-sale), public relations events, publications, a website (www.gofor2and5.com), and school and community activities. Campaign development and the evaluation framework were designed using health promotion theory, and assessed values, beliefs, knowledge and behaviour. Two independent telephone surveys evaluated the campaign: the Campaign Tracking Survey interviewed 5032 adults monitoring fruit and vegetable attitudes, beliefs and consumption prior to, during and 12 months after the campaign; and the Health & Wellbeing Surveillance System surveyed 17 993 adults between 2001 and 2006, continuously monitoring consumption.

Setting

Population public health intervention–social marketing campaign in Western Australia, population of 2 010 113 in 2005.

Subjects

Adults in the Perth metropolitan area.

Results

The campaign reached the target audience, increasing awareness of the recommended servings of fruit and vegetables. There was a population net increase of 0.8 in the mean number of servings of fruit and vegetables per day over three years (0.2 for fruit (1.6 in 2002 to 1.8 in 2005) and 0.6 for vegetables (2.6 in 2002 to 3.2 in 2005), significant at P < 0.05).

Conclusion

Sustained, well-executed social marketing is effective in improving nutrition knowledge, attitudes and consumption behaviour. The Go for 2&5® campaign provides guidance to future nutrition promotion through social marketing.
Assessing, understanding and modifying nutritional status, eating habits and physical activity in European adolescents: The HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study
Authors: Moreno LA , González-Gross M , Kersting M , Molnár D , de Henauw S , Beghin L , Sjöström M , Hagströmer M , Manios Y , Gilbert CC , Ortega FB , Dallongeville J , Arcella D , Wärnberg J , Hallberg M , Fredriksson H , Maes L , Widhalm K , Kafatos AG , Marcos A
Published: July 2007

Objectives

To identify the main knowledge gaps and to propose research lines that will be developed within the European Union-funded ‘Healthy Lifestyle in Europe by Nutrition in Adolescence’ (HELENA) project, concerning the nutritional status, physical fitness and physical activity of adolescents in Europe.

Design

Review of the currently existing literature.

Results

The main gaps identified were: lack of harmonised and comparable data on food intake; lack of understanding regarding the role of eating attitudes, food choices and food preferences; lack of harmonised and comparable data on levels and patterns of physical activity and physical fitness; lack of comparable data about obesity prevalence and body composition; lack of comparable data about micronutrient and immunological status; and lack of effective intervention methodologies for healthier lifestyles.

Conclusions

The HELENA Study Group should develop, test and describe harmonised and state-of-the-art methods to assess the nutritional status and lifestyle of adolescents across Europe; develop and evaluate an intervention on eating habits and physical activity; and develop and test new healthy food products attractive for European adolescents.
Impulsivity and Conflict in the Stroop Task
Authors: Lansbergen Marieke M. , van Hell Erika , Kenemans J. Leon
Published: July 2007

Abstract. It has been suggested that impulsive behavior can be attributed to weaker interference control. The present research used a Stroop task to test whether impulsivity within the normal population is associated with weaker interference control. Sixteen high- and 16 low-impulsive healthy volunteers performed a Stroop task, which varied in the proportion of incongruent trials to induce high conflict and provoke more impulsive behavior. Event-related brain potentials (ERP) were recorded to assess the brain correlates of Stroop interference (N/P450 and SP [sustained potential]), which have been suggested to reflect conflict processing and attentional control, respectively. Higher conflict resulted in more Stroop interference and enhanced N/P450 and SP. Source analyses indicated that the neural generators of the N/P450 and the SP may both be located near the anterior cingulate cortex (ACC), suggesting that both may reflect aspects of conflict processing. Differences in Stroop interference in terms of error rates, but not in terms of reaction time were found between high and low impulsives. This result may reflect enhanced sensitivity to the surprise value of unexpected stimulus categories, rather than enhanced interference. High impulsive participants did not differ from low impulsive participants with respect to the N/P450, but the SP seemed to originate from a more posterior and right-sided cortical network in high impulsive relative to low impulsive participants. In conclusion, high impulsiveness within the normal population as assessed by an impulsivity questionnaire is not associated with relatively early processes during response inhibition, but the present results may suggest an association between impulsiveness and further, more complex conflict processing.
Electrophysiological Indices of Processing Symmetry and Aesthetics
Authors: Höfel Lea , Jacobsen Thomas
Published: July 2007

Abstract. Evaluative aesthetic judgments and descriptive symmetry judgments were compared. Electrophysiological activity was recorded while participants judged the aesthetic value or the symmetry status of novel graphic black and white patterns. In order to experimentally separate judgment categorization processes and judgment report processes, participants were instructed to misreport their true actual judgment in half of the trials. Three effects found in a previous study were examined: (1) an early frontocentral effect for the evaluation of not-beautiful patterns reflecting an early impression formation, (2) a more pronounced ERP lateralization to the right for the aesthetic judgment task in comparison to the symmetry judgment task reflecting evaluative categorization, and (3) a sustained posterior effect for the visual analysis of symmetric patterns. In this study, (1) and (3) were replicated independent of the validity of the response, but (2) was affected by the validity, i.e., the effect was abolished in the false condition. Thus, results allowed further specification of cognitive processes involved in judgments of symmetry or aesthetics. Given present data, the ERP effects predominantly reflect judgment categorization and not judgment report.
Ocean mass variations from GRACE and tsunami gauges
Authors: Munekane H.
Published: July 2007

We compared the mass variations from Gravity Recovery and Climate Experiment (GRACE) with those measured by bottom pressure recorders (BPRs) deployed as tsunami gauges. Prior to the comparison, we estimated the degree‐1 Stokes coefficients by the degree‐1 loading method using both the GPS and GRACE data. We successfully recovered the degree‐1 Stokes coefficients that are consistent with those from the satellite laser ranging analysis and from the loading model. We found that the use of the GRACE data in the degree‐1 loading method significantly mitigates the aliasing effect from the unmodeled higher‐degree loading deformations. Then, we compared the mass variations from GRACE with those from the five BPRs that have been deployed as part of the Deep‐ocean Assessment and Reporting of Tsunamis (DART) system. We observed a fairly good (over 0.4) correlation except for one station that is close to the U.S. mainland. However, we found that the GRACE‐derived mass variations underestimate those from BPRs by nearly a factor of 2. Through numerical simulation, we found that the artificial leakage from the landmass is responsible for the low correlation observed at the station, and the spatial averaging in the GRACE processing may be responsible for the underestimation of the mass variations from BPRs by GRACE. These results illustrate the importance of performing a simulation for these effects with numerical models before comparing the GRACE‐derived mass variations with those from pointwise measurements.