bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated GPS/GLONASS navigation: Algorithms and results
Authors: Raby Peter , Daly Peter
Published: July 2007

The presence of selective availability (SA) on GPS has led to a variety of proposals for mitigation of its effects, for example combining GPS with other sensors or by identifying and removing the SA using redundant information in the position solution. A further method for reducing the impact of SA is the combination of GPS and GLONASS measurements. GLONASS does not have any deliberate degradation.

This paper describes several algorithms for combining GPS and GLONASS measurements in real time on a single receiver. There are two least squares solutions using the code phase measurements alone: one with the measurements from both systems weighted equally, and one with the measurements weighted by the covariance of the measurements. Kalman filters with no SA model, and first‐ and second‐order models, using both the code and carrier phase to estimate user position and velocity, are also implemented. Two different adaptive schemes are compared which attempt to identify SA model parameters in real time. The algorithms are compared in terms of their positioning accuracy, computational overhead and robustness. A ten‐channel GPS/GLONASS receiver developed at The University of Leeds is used to provide satellite data for the evaluation of the different methods.
RESULTS AND PERFORMANCE OF MULTI‐SITE REFERENCE STATION DIFFERENTIAL GPS
Authors: Johnston Gordon T.
Published: July 2007

This paper describes in some detail the infrastructure and concept of two multi‐site reference station differential GPS (DGPS) options being offered to marine users by Racal Survey. The infrastructure of the Racal SkyFix system is briefly outlined, followed by descriptions of Racals' internetting and network capabilities.

Comparisons between the two systems are made, including infrastructure, differential data management, user coverage, datalinks and positioning performance in various parts of the world. The paper describes the design of the systems and the tests undertaken to assess their functionality, before going on to compare their performances under a variety of conditions.

Emphasis is placed on the technical issues associated with multi‐reference‐station DGPS, including error sources, weighting observations and monitoring of the data. The paper sets out to describe the fundamental approach of the systems to achieve high data integrity which is necessary to develop the systems to their next phase.

Having described the two options, the paper uses examples of various combinations of reference stations to illustrate the potential of the system.

Real‐time operations with the internetting and network systems are then used to show the increased performance of the two options over ordinary single station DGPS and lead into the conclusions section. The conclusions summarize the paper's findings and make recommendations for the future development of the system.

The object of the developments so far has been to improve the quality of real‐time offshore DGPS positioning. The internetting and network options have provided real‐time results to illustrate the benefits and, together with SkyFix, offer significant developments in the ability of DGPS to provide accurate and reliable positioning over vast areas of the world.

The ability to compare two multi‐reference‐station DGPS systems over large areas using co‐sited reference stations is very unusual. The opportunity has been taken to compare and report on the performance of the two systems.
Investigation of signal variance, bit error rates and pulse dispersion for DSPN signalling in A mobile dense scatterer ray tracing model
Authors: Amoroso Frank
Published: July 2007

The canonical ray tracing model of R. H. Clarke is used to validate the concept of mitigation bandwidth as used to predict DSPN spread spectrum signal variability at a mobile receiving antenna in dense scatterers. Illustrative examples of chip pulse dispersion are presented, and bit error rate performance is explored under the assumption of slow fading. The pulse dispersion is seen to pose potential obstacles to any eventual chip timing extraction and radio‐location ranging functions. Serendipitously, the performance of a DSPN embodiment of a 180° DPSK data link is seen to approximate closely that of a corresponding narrowband Rician fading link, even though no specular signal component is available to the DSPN link. The parameters of the equivalent Rician link are easily predicted from those of the DSPN link.
Phase synchronization in a satellite‐mobile channel
Authors: Salis Jose M. Riera , Rio Luis Mercader Del
Published: July 2007

This paper studies several aspects relevant to the design of phase synchronization circuits for land mobile satellite systems (LMSS). First, the results of a propagation experiment are presented, with special focus on the effects of vehicle mobility on the signal phase. It is found that the changes of speed and direction cause frequency variations that can be modelled as linear. Bounds for the frequency derivative are given for different percentages of time. The use of third‐order PLLs is considered, as they are optimum for tracking a frequency ramp embedded in white Gaussian noise. The model of third‐order PLL employed is presented, as it is an original model, developed by the authors. Then the performances of second‐ and third‐order PLLs are compared. Theoretical, as well as simulation, results are given. It is shown that third‐order loops give better performance in the presence of frequency variations of the kind observed in this link, but they suffer from a higher sensitivity to oscillators' phase noise. Several conclusions regarding the use of third‐order loops in future systems are presented.
An efficient algorithm for generalized SS/TDMA scheduling with satellite cluster and intersatellite links
Authors: Kim Sehun , Kim Soo‐Hyun
Published: July 2007

We consider the satellite cluster scheduling problem, which is one of the most interesting problems in the satellite communication scheduling area. This problem is known to be NP‐complete, and a couple of heuristic algorithms have been developed. In this paper, we suggest another algorithm for this problem which has the same computational complexity as the best existing one and provides much better solution quality. Extensive computational simulation results are reported.
A comparative analysis of frequency scanning and multispot beam satellite systems for mobile communications
Authors: Cornacchini C. , Crescimbeni R. , D'Ippolito A. , Russo P. , Vernucci A. , Ruggieri M. , Jones T.
Published: July 2007

A comparative analysis between frequency scanning and multispot satellite systems has been performed in the context of land mobile applications. The aim of the work has been to confirm the effectiveness of the frequency scanning approach, whose technical feasibility has already been proved by the authors in a previous study, also in a comparative investigation with a more conventional satellite configuration.

A proper comparative methodology has been established to compare two baseline configurations of the two systems. The analysis has also been rendered parametric, varying some system characteristics such as bandwidth, traffic distributions and linearity requirement. The achieved results are provided and widely commented on in the paper.
Spectrum sharing considerations for the proposed ESA ‘archimedes’ satellite DAB service
Authors: Rudd Richard
Published: July 2007

At the 1992 World Administrative Radio Conference (WARC), spectrum was allocated, on a primary basis, to the broadcast satellite service (sound). The allocations were not, however, uniform worldwide, nor will the BSS(S) have sole use of these allocations. In addition, many countries have reserved primary use of the spectrum for existing services until 2007, with the BSS(S) permitted only on a noninterference basis.

This situation will impose serious constraints on the proposed ESA S‐DAB service, to be radiated from the ‘Archimedes’ constellation of satellites. The launch date for this service may be before the end of the century, and sharing with other spectrum users will therefore be necessary. Such users include fixed telephony links, broadcast links and mobile aeronautical telemetry.

This paper reviews current spectrum usage in Europe and elsewhere, and investigates the restrictions thus imposed on the ESA S‐DAB service. Numerical examples based on real‐world systems are given, and demonstrate the feasibility, in many cases, of spectrum sharing.
Mobile P‐service satellite system comparison
Authors: Johannsen Klaus G.
Published: July 2007

Several future operators of the mobile handheld telephone (P‐service) satellite communications systems are gearing up for system implementation to compete for the mobile handheld telephone market of the future. While these companies are proceeding with system realization, they are also looking for partners to finance these huge satellite projects. Potential partners or bulk users are administrations of national communication systems and operators of national communication satellites. These future partners ask themselves which P‐service satellite communication system they should choose.

There is not an easy answer because P‐service satellite systems come in many varieties. There are the low altitude earth orbiting satellites (LEOs), the medium altitude earth orbiting satellites (MEOs), and the geosynchronous altitude earth orbiting satellites (GEOs). Each system has a different type of satellite repeater: digital regenerative, transparent digital, and the bent‐pipe. And each satellite system uses its own modulation/multiple access system. The fact that satellites circle the earth at different altitudes has an impact on speech quality, and, because systems vary in satellite as well as constellation complexity, there are different price tags attached. All systems display ingenious features and will eventually work. Mobile users will decide which system will best serve their purposes.

This article attempts to compare six P‐service satellite systems and find a method for system selection. By use of self‐established system criteria, it is possible to arrive at a P‐service system selection. By weighing the system criteria, the sensitivity of system selection can be tested. The results or the selection of a particular system should not be considered a recommendation; rather, the process of selection should be used as a possible guideline.
Marketing margin and determinants of net returns of beef marketing in southeast Nigeria
Authors: Eze CC
Published: July 2007

This study examined: the marketing costs, margins and returns of retailed beef meat in southeast Nigeria; factors influencing the traders' net returns; problems associated with marketing of beef; and the socio‐economic characteristics of respondent traders. Sixty respondents were selected at random, with 20 respondents from each of three purposively selected markets in the study area. A structured interview schedule and personal observations were sources of primary data. The field data were analysed using cost‐return principles, multiple regression analysis and descriptive statistics. The gross margin for trading was
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9,790 (=US$81.58) per 250 kg dressed meat, with a net return of
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8,605 (=US$71.71) and an average sales receipt of
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78,400 (= US$653.33). The cost of meat, transport costs, other costs (garage fees, storage, taxes), experience in the trade and level of education significantly (p < 0.05) affected the traders' net returns. Insufficient capital, inadequate stock supply, high transport cost and storage were identified as the major problems associated with meat trading in the study area. Copyright © 2007 John Wiley & Sons, Ltd
Studies on candelilla wax. II. Itsn‐paraffins
Authors: Schuette H. A. , Baldinus Joseph G.
Published: July 2007

A simple, rapid adsorption method for the isolation of candelilla paraffins has been described. Use of the method as a quantitative procedure yielded 52.2% paraffins.

X‐ray analysis and other physical data indicated that the principal candelilla paraffin was the C31 compound. The C29 and C33 homologues were also found to be present, C29 being reported for the first time.

The presence of ketones could not be established.
Polymerization of drying oils. V. Further observations on the reaction of unsaturated dibasic anhydrides with methyl linoleate
Authors: Teeter H. M. , Kini U. S. , Myren R. A. , Cowan J. C.
Published: July 2007

Adducts of methyl linoleate with itaconic and citraconic anhydrides have been prepared. Each adduct was separated into monomeric and polymeric components. With ethylene diamine, the itaconic and citraconic polymeric adducts gave gelled products at 170° in one hour and 3.5 hours, respectively. The adduct of citraconic anhydride and monomeric distillate gave a tough, tacky resin which did not gel during a reaction time of 20 hours at 170°–180°.

The effect of dimethylaniline on the condensation of methyl linoleate and maleic anhydride was studied. Increasing amounts of dimethylaniline were found to promote the formation of a heteropolymer and to decrease the yield of liquid adduct.
Evaluation of peanut protein for industrial utilization. A review
Authors: Arthur Jett C.
Published: July 2007

The properties of peanut protein have been briefly reviewed, and procedures for the evaluation of this protein for different industrial uses have been indi cated. The determination of the solubility of the protein in different solvents, analysis of the isolated protein to determine its nitrogen and ash contents and its color when dispersed in sodium hydroxide solutions, determinaztion of the viscosity characteristics of concentrated peanut protein solutions, and specific product testing are used to evaluate peanut protein for industrial utilization.
Modified procedures for determination of gossypol pigments. II. Determination of free gossypol in low gossypol meals and of gossypol in oils
Authors: Deacon Benjamin D.
Published: July 2007

Much of the «free» gossypol in meals of low free gossypol content consists of «soluble‐bound» gossypol. Addition of dilute hydrochloric acid reduces the optical densities of gossypol blanks in free and total gossypol calibrations and assays. The reductions in these optical densities were lower than expected in free gossypol assays on meals of lower free gossypol content. The soluble‐bound gossypol in these can be converted into gossypol by heating the extracts with dilute acid at 100C. This does not affect the optical densities of the nongossypol pigments, nor does it affect the optical densities obtained on heating with aniline. The procedure affords more accurate analyses for these meals. A similar modification has been developed for gossypol in oils.
Perceived consequences among pregnant and non‐pregnant women of continuing or ceasing to smoke
Authors: Näsman P. , Ortendahl M.
Published: July 2007

Objective

To examine the perception of risk of smoking‐related psychological and social outcomes, and the effect of pregnancy and intention to stop smoking on the perceived risk.

Methods

Eighty women were asked to make judgments about the probability of outcomes for smoking‐related consequences. Four subgroups were created using the variables of pregnancy (pregnant versus not pregnant) and cessation of smoking (intention to stop versus no intention to stop). Judgments were based on the decision to stop and not stop smoking.

Result

Intention to stop smoking affected the estimated probabilities for the occurrence of consequences for both continuing and stopping smoking, whereas pregnancy did not affect the estimated probabilities. The estimated effect of stopping smoking was statistically significant.

Conclusion

Health messages about smoking for all population groups should consider both future risk of mortality and immediate quality‐of‐life effects of smoking.
IDENTIFICATION OF STABLE RESISTANCE TO PHYTOPHTHORA INFESTANS IN POTATO GENOTYPES EVALUATED IN FIELD EXPERIMENTS IN PERU
Authors: WULFF E. G. , PÉREZ W. , NELSON R. J. , BONIERBALE M. , LANDEO J. A. , FORBES G. A.
Published: July 2007

In this study, genotype by environment (G × E) interactions and phenotypic stability of resistance to Phytophthora infestans, the cause of late blight, were analysed in Peru for 13 potato genotypes, using additive main effects and multiplicative interaction (AMMI) analysis and Huehn's non-parametric test. The potato genotypes were tested in seven experiments over two years in the vicinity of Comas, Peru, an area used by the International Potato Center to screen for resistance to late blight. Results of the two analyses generally correlated and indicated that quantitative resistance to P. infestans was stable under field conditions for all the genotypes tested. The first two principal components (PCA1 and PCA2) of the AMMI analysis explained 54% of the G × E interaction sum of squares. A biplot of the two principal components demonstrated a strong year effect in the G × E interaction. By plotting yearly means of the relative area under the disease progress curve (rAUDPC), genotypes could be assigned to one of three resistance categories, resistant, moderately resistant or susceptible, but the need for a more readily applicable and truly quantitative scale for resistance was noted. Based on these studies, standards can be selected for use in screening in the area where they were tested. After further testing in other locations, a standard set drawn from these genotypes could be identified and a quantitative scale developed for evaluation of resistance under short day conditions.
SEASON OF BIRTH AND CHESS EXPERTISE
Authors: GOBET FERNAND , CHASSY PHILIPPE
Published: July 2007

The origin of talent and expertise is currently the subject of intense debate, with explanations ranging from purely biological to purely environmental. This report shows that the population of expert chess players in the northern hemisphere shows a seasonal pattern, with an excess of births in late winter and early spring. This effect remains when taking into account the distribution of births in the population at large, using statistics from the European Union member countries. A similar pattern has been found with schizophrenia, and the possible link between these two phenomena is discussed.
A review of diuretic use in older people
Authors: Laidlaw Dr Simon , Gillespie Dr Neil
Published: July 2007

Diuretics are commonly prescribed in older people and are often used for prolonged periods. Indications for their use include heart failure and hypertension. They are also used to empirically treat complaints such as swollen ankles and shortness of breath. The aging body is particularly susceptible to the adverse effects of diuretic therapy. Many of the problems are a result of intravascular and extravascular fluid imbalance. It is therefore important that diuretics are prescribed rationally and with good reason. Most major clinical trials do not include older people with multiple co-morbidities. This review will consider whether trials involving diuretics are any different, through an evaluation of what evidence there is to support diuretic use in older people. We will also evaluate the evidence which implicates diuretics as a cause of common clinical problems such as falls, postural hypotension and incontinence. Finally, a rational approach to the use of diuretics in older people will be suggested so that the benefits of diuretic therapy can be maximized and potential adverse effects minimized.
Theory and applications of term graph rewriting: introduction
Authors: MACKIE IAN , PLUMP DETLEF
Published: July 2007

Term graph rewriting is concerned with the representation of functional expressions as graphs and the evaluation of these expressions by rule-based graph transformation. The advantage of computing with graphs rather than terms is that common subexpressions can be shared, improving the efficiency of computations in space and time. Sharing is ubiquitous in implementations of programming languages: many functional, logic, object-oriented and concurrent calculi are implemented using term graphs.
A rewriting calculus for cyclic higher-order term graphs
Authors: BALDAN PAOLO , BERTOLISSI CLARA , CIRSTEA HORATIU , KIRCHNER CLAUDE
Published: July 2007

The Rewriting Calculus (ρ-calculus, for short) was introduced at the end of the 1990s and fully integrates term-rewriting and λ-calculus. The rewrite rules, acting as elaborated abstractions, their application and the structured results obtained are first class objects of the calculus. The evaluation mechanism, which is a generalisation of beta-reduction, relies strongly on term matching in various theories.

In this paper we propose an extension of the ρ-calculus, called ρg-calculus, that handles structures with cycles and sharing rather than simple terms. This is obtained by using recursion constraints in addition to the standard ρ-calculus matching constraints, which leads to a term-graph representation in an equational style. Like in the ρ-calculus, the transformations are performed by explicit application of rewrite rules as first-class entities. The possibility of expressing sharing and cycles allows one to represent and compute over regular infinite entities.

We show that the ρg-calculus, under suitable linearity conditions, is confluent. The proof of this result is quite elaborate, due to the non-termination of the system and the fact that ρg-calculus-terms are considered modulo an equational theory. We also show that the ρg-calculus is expressive enough to simulate first-order (equational) left-linear term-graph rewriting and α-calculus with explicit recursion (modelled using a letrec-like construct).
Die Posttraumatische Belastungsstörung nach Verkehrsunfällen
Authors: Bölter Annette , Süß Heinz-Martin , Schuschke Tankred , Tempka Almut , Klapp Burghard F. , Draijer Fred , Frommer Jörg
Published: July 2007

Zusammenfassung: Die vorliegende Studie untersucht die Auftretensrate der Posttraumatischen Belastungsstörung (PTSD) drei bis vier Monate nach einem Verkehrsunfall sowie ihre Vorhersagbarkeit durch eine frühzeitige Datenerhebung. Untersucht wurde der Einfluss einer akuten PTSD-Symptomatik kurz nach dem Unfall sowie Risikofaktoren, die aus einschlägigen Theorien abgeleitet wurden. Dazu wurden 48 Verkehrsunfallopfer, die Patienten auf unfallchirurgischen Stationen waren, durchschnittlich elf Tage nach dem Unfall zu ihrer Soziobiografie und zum Unfallhergang befragt. Zum gleichen Zeitpunkt sowie dreieinhalb Monate nach dem Unfall wurde mit dem SKID-PTSD diagnostiziert, ob eine PTSD-Symptomatik vorliegt. Im Untersuchungsdesign fanden empirische sowie methodische Kontrollen für die Untersuchung psychotraumatischer Auswirkungen durch physische Verletzung Berücksichtigung. Die Auftretensrate betrug 18.8 % für eine voll ausgeprägte und 14.6 % für eine subsyndromale PTSD. Als Risikofaktoren für deren Entstehen konnten das weibliche Geschlecht, eine hohe materielle Verlusteinschätzung, das Vorhandensein einer posttraumatischen Akutsymptomatik sowie Variablen des Erholungsverlaufs hervorgehoben werden. Eine logistische Regression ergab, dass eine PTSD-Symptomatik zu 75 % korrekt mit diesen Variablen vorhergesagt werden kann. Die Relevanz der Ergebnisse für künftige Studien wird diskutiert.
Arbeitsgedächtnisfunktionen bei lernbehinderten Kindern und Jugendlichen
Authors: Mähler Claudia
Published: July 2007

Zusammenfassung. Gedächtnisanforderungen stellen für Kinder mit Lernbehinderung eine besondere Herausforderung dar. Defizite im Bereich von Metagedächtnis und Strategien sind seit langem bekannt; in jüngerer Zeit wird verstärkt die Funktionstüchtigkeit des Arbeitsgedächtnisses untersucht und die Frage gestellt, in welchen Subsystemen des Arbeitsgedächtnismodells nach Baddeley (1986) mit Defiziten zu rechnen ist. Außerdem wird erörtert, ob die beobachtbaren Defizite als Ausdruck einer Entwicklungsverzögerung oder als qualitative Abweichung von der normalen Entwicklung aufzufassen sind. In einem 5-Gruppen-Design wurde zu zwei Gruppen lernbehinderter Kinder unterschiedlichen Alters (10 Jahre und 15 Jahre) jeweils eine Gruppe von durchschnittlich intelligenten Kindern gleichen mentalen und gleichen chronologischen Alters rekrutiert. Alle Kinder bearbeiteten 7 Aufgaben einer Arbeitsgedächtnisbatterie (2 Aufgaben zur Zentralen Exekutive, 3 Aufgaben zur Phonologischen Schleife und 2 Aufgaben zum Visuell-räumlichen Notizblock). Die Ergebnisse belegen Defizite der Kinder mit Lernbehinderung in allen untersuchten Arbeitsgedächtnisfunktionen. Als besonders gravierend stellte sich die Beeinträchtigung der phonologischen Schleife bei zehnjährigen lernbehinderten Kindern heraus. Die Ergebnisse unterstützen die Einschätzung, dass insbesondere bei leichter intellektueller Minderbegabung ein wichtiger Ursachenfaktor für schulische Lernschwierigkeiten in der phonologischen Informationsverarbeitung begründet sein könnte.
Normative Variation of P3a and P3b from a Large Sample
Authors: Conroy Matthew A. , Polich John
Published: July 2007

Abstract. The P3a and P3b components were elicited in 120 (60 females, 60 males) young adults using a visual three-stimulus event-related brain potential (ERP) oddball paradigm in which subjects responded to an infrequent target. The major purpose of the paper was to provide a statistically strong characterization of these related P300 subcomponents. P3a components were obtained from the infrequently presented distracter stimulus, which was a large blue square. P3b components were obtained from the target stimulus, which was a blue circle that differed slightly in diameter from the standard stimulus blue circle. Amplitude measures demonstrated that P3a was maximum at Cz, and P3b was maximum at Pz; latency measures increased for both potentials from frontal to parietal recording sites. P3a and P3b from females were larger and later than those from male subjects, with topographic and appreciable individual difference variability observed. P3a was generally unrelated to response time. P3b amplitude was negatively correlated over right frontal areas with P3b latency and positively correlated over right parietal areas to response time. Theoretical implications are discussed.
Insights into the ground attachment process of natural lightning gained from an unusual triggered‐lightning stroke
Authors: Jerauld J. , Uman M. A. , Rakov V. A. , Rambo K. J. , Schnetzer G. H.
Published: July 2007

We present measured electric and magnetic field and current derivatives from an unusual triggered‐lightning stroke that was initiated by a dart‐stepped leader and that involved an upward connecting leader. The initial rising portion of the current (integrated dI/dt) waveform is composed of a “slow front” rising to 20 kA in 2.2 μs, followed by a “fast transition” from 20 to 27 kA in 0.2 μs. A similar slow‐front/fast‐transition sequence has been observed in the currents and in the distant radiation fields of natural‐lightning first strokes. Field derivatives measured at 15 and 30 m for the triggered‐lightning stroke are similar to those measured for natural‐lightning first strokes occurring within a few hundred meters. Two versions of the transmission line model, with the measured current derivative and assumed propagation speeds as input, are able to reasonably reproduce the slow fronts and fast transitions in the field derivatives measured at 15 and 30 m (the electric field slow front being primarily electrostatic) and predict the slow front in the distant radiation fields. These results suggest that the source of the slow fronts observed in the currents and in the distant radiation fields of natural first strokes is likely to be a pair of microsecond‐scale current waves, each having a peak of up to some tens of kiloamperes, propagating in opposite directions from the junction of the descending and upward connecting leaders at a speed on the order of 108 m s−1, rather than the upward connecting leader itself, as is often thought.
Sources of the oxygen isotopic anomaly in atmospheric N2O
Authors: Liang Mao‐Chang , Yung Yuk L.
Published: July 2007

One‐dimensional and two‐dimensional models are used to investigate the isotopic composition of atmospheric N2O. The sources of N2O in the atmosphere are based on recent laboratory measurements of the N2O quantum yield in the mixture of O3/O2/N2 (Estupiñán et al., 2002). Two recently proposed pathways (Estupiñán et al., 2002; Prasad, 2005) are evaluated in the model. We find that the new atmospheric sources constitute a few percent of the total N2O source, but can account for ∼50–100% of the Δ17O anomaly observed in N2O. The essence of the mechanism is to transfer a heavy oxygen atom originally in O3 to N2O. The magnitude of Δ17O in N2O is a linear function of the strength of these new N2O sources. Laboratory and atmospheric measurements are proposed to confirm the chemical pathways. The potential of Δ17O in N2O for providing a new tool to probe ozone levels in paleoatmospheres is discussed.
High resolution mapping of TiO2 abundances on the Moon using the Hubble Space Telescope
Authors: Robinson M. S. , Hapke B. W. , Garvin J. B. , Skillman D. , Bell J. F. , Ulmer M. P. , Pieters C. M.
Published: July 2007

Samples of the lunar regolith returned by Apollo astronauts show large variations (0 to >10 wt%) in TiO2 abundance indicating complex compositional zonation within the lunar mantle. A long held goal of the lunar science community is the accurate determination of TiO2 abundances on the lunar surface through remote sensing methods. To date only limited progress has been made in this area using spacecraft spectral measurements acquired in visible through near‐infrared wavelengths. Here we show that variations in the ratios of ultraviolet (UV) to visible (VIS) reflectances in images taken by the Hubble Space Telescope indicate a strong correlation with TiO2 abundances determined from returned samples at the Apollo 17 landing site, and little correlation with the “maturity” of lunar soils. These new findings imply that UV‐VIS observations may lead to an alternate and improved method of remotely mapping TiO2‐bearing materials (probably as ilmenite) across the lunar surface and enable more refined studies of lunar crustal composition, surface volcanism, and subsurface magma evolution processes. Additionally, accurate identification and quantification of TiO2 rich deposits serves to guide future human exploration of the Moon.
Antibody against Bacillus thuringiensis phosphatidylinositol‐phospholipase C: Some examples of its potential uses
Authors: Théveniau M. A. , Malapert P. , Rougon G. N.
Published: July 2007

We have purified the phosphatidylinositol‐phospholipase C enzyme from the bacterium Bacillus thuringiensis. This enzyme is able to release in soluble form molecules which are anchored lo membranes via a glycan‐phosphatidylinositol group. It exhibits a molecular weight of 33–35 kDa. We raised polyclonal antisera against the molecule and used them in immunoblot as well as radioimmunoassays for enzyme detection. This last technique should facilitate monitoring of chromatographic steps during enzyme purification. We coupled antibodies to Sepharose beads in order to remove the enzyme from incubation media. This reagent also proved to be particularly useful in control experiments designed to ascertain that the observed release of molecules is due to the action of the phosphatidylinositol‐phospholipase C enzyme and not to spontaneous release or to cleavage by nonspecific hydrolases. A search for cross‐reactive molecules in other bacterial strains or mammalian tissues gave negative results. This leads to the conclusion that a great diversity exists between phosphatidylinositol‐phospholipases C, even among different bacterial strains.
Presentation of Salmonella antigens by peritoneal cells of normal and Salmonella‐infected mice
Authors: Vordermeier H. M. , Pope M. , Kotlarski I.
Published: July 2007

A comparison of the ability of normal peritoneal cells (PC) and those harvested from mice 1–3 days after intraperitoneal immunization with live Salmonella enteritidis 11RX (11RX) to present antigen to 11RX‐primed T cells was made using formalin‐killed 11RX and a soluble 11RX antigen extract as antigens. Unfractionated PC and the adherent and non‐adherent PC populations were analysed separately and the effects of the lysosomal function‐impairing drug chloroquine and the fixative paraformaldehyde, used before or after antigen‐pulsing, were also determined. The results presented indicate that immunization with live 11RX did not induce any detectable modulation of APC function which could account for the ability of live 11RX to induce cell‐mediated immune responses involving Lyt 2+ T cells.
Immune response to Acanthocheilonema viteae infection in multimammate rats (Mastomys natalensis)
Authors: Chandrashekar R. , Rao U. R. , Subrahmanyam D.
Published: July 2007

The multimammate rat Mastomys natalensis, when infected with the filarial parasite Acanthocheilonema viteae, develops amicrofilaraemia. Worm recovery and the duration and intensity of microfilaraemia were analysed and related to the humoral and cellular immune responses of the host by using an antibody‐dependent cell‐mediated cytotoxicity (ADCC) assay towards microfilariae (Mf). Mf were detected in the peripheral blood at 7 weeks post‐infection (p.i.), reaching maximum levels by 20 weeks p.i., and then gradually decreasing to undetectable levels during the next 36 weeks. The cytotoxic antibodies appeared around 15–18 weeks p.i., and the serum at 36 weeks p.i. induced 70% cytotoxicity to the Mf in vitro in the presence of host cells. The IgM fraction of the immune serum from amicrofilaraemic Mastomys promoted ADCC to Mf both in vitro and in vivo. Macrophages were more potent in inducing cytotoxic effect than eosinophils and neutrophils. Platelets were ineffective in killing the Mf in the presence of immune serum. IgM antibody cleared the circulating Mf from the blood when given passively to infected Mastomys. The average recovery of adult worms was about 20% of the inoculated larvae. No live females could be recovered 56 weeks p.i. Thus protective immune responses built up over an extended period of time are elicited against the Mf and perhaps even to adults in Mastomys infected with A. viteae.
Monoclonal antibodies to carcino‐embryonic antigen
Authors: Teh Jin‐Ghee , McKenzie Ian F. C.
Published: July 2007

Several approaches were made to produce new monoclonal antibodies (MoAb) to human colonic tumours using different immunogens, such as colon cell lines, and tissue and serum from patients with colon cancer. Six MoAb were produced but all were found lo be reactive with carcino‐embryonic antigen (CEA). Through tissue reactivity and competitive inhibition studies it was found that four epitopes could be detected: CEA‐I detected by MoAb I‐l and O‐l; CEA‐2 detected by MoAb i7C4; CEA‐3 detected by MoAb LK‐4 and XPX‐13 and CEA‐4 detected by MoAb JGT‐13. CEA‐2 was also found on granulocytes and probably detects normal cross‐reacting antigen (NCA). In formalin‐fixed tissues the CEA‐specific epitopes were absent from normal adult tissues, but this was an artefact of the fixation procedure and fresh, non‐fixed colonic tissues were clearly reactive. All six MoAb reacted with > 70% of colonic tumours when tested by the immunoperoxidase technique and gave different patterns of reactivity reflecting the differential expression of the CEA 1–4 epitopes. Despite the apparent specificity of these MoAb for colon cancer, serum testing using MoAb gave similar results to CEA polyclonal antibodies, that is the MoAb gave no obvious advantage. Thus efforts to produce new reagents to colon cancer yielded only anti‐CEA monoclonal reagents. Clearly, other new approaches are required to produce better diagnostic reagents for this common disease.
Anti‐asialo‐GM1 inhibits vaccinia virus infection of murine ovaries: Asialo‐GM1 as an additional virus receptor?
Authors: Karupiah Gunasegaran , Blanden Robert V.
Published: July 2007

The neurovirulent strain of vaccinia virus, VV‐WR, or recombinants derived from VV‐WR, cause highly productive infection of murine ovaries, but infection could be partially inhibited in vivo using an antiserum to asialo‐GM1 (as‐GM1). In vitro analysis by flow cytometry revealed that murine ovarian cells expressed a cell surface antigen identical to or cross‐reactive with as‐GM1. The capacity of VV‐WR to infect murine ovaries appears to depend in part upon as‐GM1expression on ovarian cells.
Couette flow with a bidisperse particle mixture
Authors: Liu Xue , Metzger Matthew , Glasser Benjamin J.
Published: July 2007

We investigate the steady-state solutions of granular Couette flows with a bidisperse particle mixture. The Couette geometry allows us to study segregation in a simple nonuniform flow. Two continuum models using kinetic theory are examined, and their results are compared with particle dynamic (PD) simulations. A notable difference between the two models is their treatment of energy partition (equipartition versus nonequipartition). We consider mixtures of particles with different sizes, masses, and densities. For Couette flows, we find that energy equipartition breaks down with an increase in the system inelasticity and the mass ratio. The effect of the size ratio on nonequipartition of granular energy is very small if the two particle species have the same mass. Two forms of segregation are studied in the present work: total solids segregation in the system and solids species segregation. Total solids segregation is related to the distribution of the granular energy across the walls. Solids species segregation is due to a competition of three diffusion forces: the thermal diffusion force, the ordinary diffusion force, and the pressure diffusion force. For equal density but different size particles, we observe quantitative differences between the two continuum models, where one model predicts a much greater degree of both total solids and solids species segregation than the other model. For equal size but different mass particles, we observe qualitative differences between the models where one model and PD simulations predict a segregation transition based on the particle mass, which is not seen in the other model for the conditions we have examined.
Tornado-like flows
Authors: Yih Chia-Shun
Published: July 2007

Simple exact solutions for horizontal flows, with a stagnant funnel consisting of a lighter fluid and narrowing toward the ground, exhibit the main features of real tornadoes. The two-fluid model is quite robust, as it can be adapted to any vorticity distribution, any vertical stratification, and the effects of compressibility.
Refractive index and wavenumber properties for cyclotron resonant quasilinear diffusion by cold plasma waves
Authors: Albert J. M.
Published: July 2007

Wave-particle interactions have a large effect on magetospheric particles, in the radiation belts and elsewhere. Bounce-averaged quasilinear diffusion coefficients have been calculated for whistler hiss and chorus and electromagnetic ion cyclotron waves (EMIC), which are all believed to play major roles. To perform these calculations efficiently, techniques have been developed that use properties of the refractive index of these modes to identify ranges of wave-normal angle that are compatible with cyclotron resonance in a given frequency band. Other cold plasma waves, in the L-X, L-O, R-X, and Z modes, can also resonate with energetic electrons, and some preliminary calculations of their diffusion coefficients have been reported. Here, it is shown that the refractive index of these modes allows the techniques developed for whistler and EMIC waves to be applied to them as well. Sample calculations are presented for Z mode waves, with ωpe>Ωe and ωpe<Ωe. It is also observed that for any cold plasma mode, the wavenumber is an increasing function of frequency for a fixed value of wave-normal angle; this is proved algebraically with mild approximations and verified numerically for a very wide range of parameters. This allows a variant of the technique for efficiently calculating diffusion coefficients.
Efficient calculation of van der Waals dispersion coefficients with time-dependent density functional theory in real time: Application to polycyclic aromatic hydrocarbons
Authors: Marques Miguel A. L. , Castro Alberto , Malloci Giuliano , Mulas Giacomo , Botti Silvana
Published: July 2007

The van der Waals dispersion coefficients of a set of polycyclic aromatic hydrocarbons, ranging in size from the single-cycle benzene to circumovalene (C66H20), are calculated with a real-time propagation approach to time-dependent density functional theory (TDDFT). In the nonretarded regime, the Casimir-Polder integral is employed to obtain C6, once the dynamic polarizabilities have been computed at imaginary frequencies with TDDFT. On the other hand, the numerical coefficient that characterizes the fully retarded regime is obtained from the static polarizabilities. This ab initio strategy has favorable scaling with the size of the system—as demonstrated by the size of the reported molecules—and can be easily extended to obtain higher order van der Waals coefficients.
Magnetostructural transformation, microstructure, and magnetocaloric effect in Ni-Mn-Ga Heusler alloys
Authors: Ingale Babita , Gopalan R. , Raja M. Manivel , Chandrasekaran V. , Ram S.
Published: July 2007

Magnetostructural transformation and the associated magnetic entropy change were investigated in Ni-rich ferromagnetic Heusler alloys. A direct transformation from the ferromagnetic martensite phase to the paramagnetic austenite phase was observed in selected Ni54.8Mn20.3Ga24.9 and Ni55Mn18.9Ga26.1 two-alloy compositions. The magnetic and martensitic transformations were incurred at nearly the same temperature (351 K) in the Ni54.8Mn20.3Ga24.9 alloy. Such a typical composition involves a change of the magnetic entropy ΔSM as large as −7.0 J/kg K at 332 K in an applied magnetic field of 1.2 T.
Characterization and modeling of n-n Si∕SiC heterojunction diodes
Authors: Pérez-Tomás A. , Jennings M. R. , Davis M. , Covington J. A. , Mawby P. A. , Shah V. , Grasby T.
Published: July 2007

In this paper we investigate the physical and electrical properties of silicon layers grown by molecular beam epitaxy on 4H-SiC substrates, evaluating the effect of the Si doping, Si temperature deposition, and SiC surface cleaning procedure. Si∕SiC monolithic integration of Si circuits with SiC power devices can be considered as an attractive proposition and has the potential to be applied to a broad range of applications. X-ray diffraction and scanning electron microscopy are used to determine the Si crystal structure (cubic silicon) and morphology. I-V and C-V measurements are performed to evaluate the rectifying diode characteristics along with the Si∕SiC built-in potential and energy band offsets. In the last section, we propose that our Si∕SiC heteojunction diode current characteristics can be explained by an isojunction drift-diffusion and thermoionic emission model where the effect of doping concentration of the silicon layer and its conduction band offset with SiC is analyzed.
Differential heterodyne interferometer for measuring thickness of glass panels
Authors: Protopopov Vladimir , Cho Sunghoon , Kim Kwangso , Lee Sukwon , Kim Hyuk
Published: July 2007

Differential heterodyne interferometer is applied for measuring spatial thickness variations across glass panels of liquid-crystal displays. This system uses the Zeeman laser as a source of two-frequency shifted orthogonally linearly polarized probe waves, passing through the glass in two spatially separated points. These waves are then recombined in a single beam to produce the intermediate frequency signal with the phase proportional to the thickness gradient of a glass sample. The phase of the intermediate signal is measured against the laser reference by means of a lock-in amplifier, and finally real-time integration provides the thickness variation. Since spatial separation of the probe beams is only 1.35mm good approximation for the thickness gradient is achieved. Detailed design of the interferometer and experimental results on real samples are presented.
Scanning nonlinear magnetic microscopy
Authors: Endo Makoto , Ohara Koya , Cho Yasuo
Published: July 2007

Scanning nonlinear magnetic microscopy (SNMM) is introduced as a new microscopic technique for measurement of the distribution of magnetization. The technique is based on the detection of inductance variation in a magnetic material under application of an external alternating magnetic field. The measured inductance thus reflects the nonlinear magnetic response of the material, giving the nonlinear magnetic permeability (μ333) and the direction and magnitude of magnetization. SNMM is demonstrated in application to measurement of the magnetization distribution of a floppy disk.
Rosen-type Pb(Mg1∕3Nb2∕3)O3–PbTiO3 single crystal piezoelectric transformer
Authors: Wang Feifei , Wu Jun , Jia Yanmin , Zhu Hua , Zhao Xiangyong , Luo Haosu
Published: July 2007

In this study, a Rosen-type Pb(Mg1∕3Nb2∕3)O3–PbTiO3 single crystal piezoelectric transformer is presented. First, we simulate the operation of this transformer using the finite element method and ANSYS. By adjusting the dimensions of the piezoelectric transformer, a maximum voltage step-up ratio of 138 can be obtained at a frequency of 33.8kHz when the output part is open. Second, we fabricate a transformer with the size of 20mm length, 4mm width, and 1mm thickness to examine the simulation results. It is found that this transformer exhibits a maximum voltage step-up ratio of 134 at 37kHz, with the efficiency over 95% when driving a liquid crystal display backlight, which shows good consistency with the numerical simulation results. Besides, we investigate the electrical properties under different frequencies and load resistances. When the input voltage increases, a maximum output power of 1W is obtained with the temperature rise less than 10°C.
Near-infrared sensitive small molecule organic photovoltaic cells based on chloroaluminum phthalocyanine
Authors: Bailey-Salzman Rhonda F. , Rand Barry P. , Forrest Stephen R.
Published: July 2007

The use of chloroaluminum phthalocyanine (ClAlPc) as a donor and C60 as an acceptor in planar double heterojunction organic photovoltaic cells with response extending into the near infrared is demonstrated. X-ray diffraction indicates that under the conditions used in this study ClAlPc grows as an amorphous film. Although the absorption and film morphology show no dependence on growth rate, device performance is optimized at a growth rate of 0.5Å∕s, producing cells whose best performance gives an open circuit voltage of 0.68±0.01V, a responsivity of 0.062±0.007A∕W, a fill factor of 0.50±0.04, and a power conversion efficiency of 2.1±0.1% under simulated AM1.5G, 1 sun intensity illumination. This cell also displays low dark current under reverse bias, 2.4×10−8A∕cm2 at −1V.
On the entropy flow properties of a severe tropical storm
Authors: Liu Y. , Liu C.
Published: July 2007

The relationship of entropy flow with the evolution of a severe tropical storm is investigated in this letter, based on observational analyses covering its life cycle. The formula for calculating entropy flow is derived starting with the Gibbs relation [S. R. De Groot and P. Mazur, Non-equilibrium Thermodynamics (North-Holland, Amsterdam, 1962)], in terms of constant pressure coordinates. The results show that negative entropy flow plays an important role in the storm growth with the entropy flow being basically the entropy advection, suggesting that entropy flow analysis is a powerful tool in understanding the mechanism responsible for the evolution of storms.