bluuebunny/crossref_metadata_2025_split huggingface dataset:
11·6 GHz rain attenuation measurements in Peru
Authors: Dissanayake A. W. , McCarthy D. K. , Allnutt J. E. , Shepherd R. , Arbesser‐Rastburg B. 
Published: July 2007

AbstractThis paper presents the results of a Ku‐band propagation experiment conducted in a high‐rainfall‐rate region in Peru. Sky noise measurements were made with an 11·6 GHz radiometer over a period of 18 months. Simultaneous rainfall was also recorded with a tipping bucket rain‐gauge. The paper describes the experimental equipment, the characteristics of the measurement site, and the results obtained from the experiment in the form of long‐term distributions of rain rate and path attenuation. Duration statistics of attenuation are also presented.In the absence of an absolute calibration of the radiometer in terms of the path attenuation, selection of the best medium temperature to be used poses a problem. For comparison, sky noise to path attenuation conversion was done with two medium temperatures, 280 and 290 K. When compared with model predictions, 290 K seems to be more appropriate for the climate concerned. Both the attenuation and fade duration statistics are found to follow a lognormal distribution fairly closely.
Doppler‐shift correction for a UQPSK satellite modem
Authors: Clark A. P. , Aftelak A. 
Published: July 2007

AbstractThe paper describes a novel development of a previously described technique for the measurement and correction of the Doppler shift (frequency offset) in a received UQPSK signal that has been transmitted over a satellite link. The satellite is here assumed to be in a non‐geostationary orbit, so that it introduces a large and time‐varying Doppler shift into the transmitted data signal. Correction of the Doppler shift must be achieved as soon as the satellite rises above the horizon and with no prior knowledge at the receiver of the transmitted data. Furthermore, under the given conditions, the signal/noise ratio can be very low and the Doppler shift very high. A non‐data‐aided technique has therefore been selected, capable of operating under seriously adverse conditions. Results of computer‐simulation tests are presented to measure the time taken to correct an initial Doppler shift of 5 kHz in the received UQPSK signal, at low signal/noise ratios.
Performance of a circular signal set in a regenerative satellite system employing TWTA or SSPA
Authors: Cheung S. W. 
Published: July 2007

AbstractThis paper presents the results of a computer‐simulation study of a (4,12) circular signal set for use over regenerative satellite links. The signal has a 16‐ary symbol alphabet. The satellite transponders and each of the earth‐stations use either travelling‐wave‐tube amplifiers (TWTAs) or solid‐state power amplifiers (SSPAs) for high‐power amplification. Several different earth‐stations are assumed to have simultaneous access to a given regenerative satellite, in an arrangement of frequency division mulitple access (FDMA). Thus, adjacent‐channel‐interference (ACI) can be introduced into the wanted signal by the immediately adjacent channels. The performances of the signal are compared to those of a 16‐ary differentially encoded‐quadrature‐amplitude‐modulated (16‐ary DEQAM) signal with a rectangular signal set and the results are used to determine the preferred signal set for spectrally efficient transmission over satellite links. It has been shown that, with TWTAs used for high‐power amplification and in the absence of ACI, the circular signal set has an advantage of about 3 dB over the rectangular signal set, at the bit error rate of 10−4. While in the presence of the ACI, the advantage is 2 dB. With SSPAs, the respective advantages become 0·7 and 0·5 dB.
The DTX‐240D digital circuit multiplication system
Authors: Murphy Ron 
Published: July 2007

AbstractThis paper describes the DTX‐240D digital circuit multiplication system (DCMS) offered by ECI Telecom. It will accept up to 240 × 64 kb/s trunks carrying either 64 kb/s voice, voice band analogue non‐speech signals, or digital data for transmission over a 2·048 Mb/s digital link. Over 1000 are currently ‘on‐line’ and carrying traffic.The system comprises a pair of terminals, one on each side of the interterminal digital link (bearer). It will normally operate in the network at a concentration ratio of 5:1, in which case 150 × 64 kb/s trunks, carrying voice, voice band data or digital data can be concentrated into one 2·048 Mb/s bearer. The users are able to increase the number of trunks up to 240 per 2·048 Mb/s bearer, when time zone differences cause a spread of busy‐hour traffic carried on a single system. Each terminal will normally be located at an international switching centre (ISC) but may also be located at an earth‐station.The system uses a DSI (digital speech interpolation) stage providing a 2·5:1 multiplication, followed by an additional 2:1 multiplication by means of ADPCM (adaptive differential pulse code modulation). In addition, the VBR (variable bit rate) technique is used to prevent clipping, due to overload congestion.The system can also be used with 1·544 Mb/s digital bit streams (trunk side or bearer).
An efficient protocol for providing integrated voice/data services to mobiles over power‐limited satellite channels
Authors: Bose Sanjay K. 
Published: July 2007

AbstractVarious mobile satellite communication systems are being developed for providing integrated voice/data services over a shared satellite transponder which is power‐limited in nature. A common strategy is to use slotted ALOHA request channels to request channel assignments for voice/data calls from a network management station. To maximize efficiency in a system with a power‐limited satellite transponder, it is proposed that the bursty nature of voice sources be exploited by the NMS to ‘over‐assign’ channels. This may cause problems of inefficiency, potential instability as well as a degradation in the quality of service offered to the customers. Augmenting this with the introduction of simple state‐dependent control procedures provides systems which exhibit more desirable operational features. This approach is proposed and examined in this paper.
Frequency and time stability of GPS and glonass clocks
Authors: Daly Peter , Kitching Ian D. , Allan David W. , Peppler Trudi K. 
Published: July 2007

AbstractThe frequency stability and reliability of the clocks are critical to the success of the GPS and GLONASS programs. We will show some of the similarities and differences between the clocks involved in these two systems. Because both systems plan to be operational in the next few years, the data leading up to this operational stage is of significant interest. On‐board clocks and the stability of the master control clocks for these systems are analysed.We will discuss the attributes of these two systems as time and frequency references. Their relationship to UTC will also be illustrated. More data over a longer period of time was available for the authors from GPS than from GLONASS. Even so it is obvious that both systems have matured. Though the GLONASS system was developed later, its overall clock performance has improved more rapidly. Some of the more recent GLONASS clock performance is at about the same level as that of the GPS clocks.The analysis has yielded some very interesting contrasts, comparisons and changes in these systems that should be of great interest for time and frequency users, as well as for clock vendors and receiver vendors.
The german dfs and tv‐sat satellite control centre in usingen
Authors: Altmann Bernd , Damiano Antimo , Piani Gianguido 
Published: July 2007

AbstractThis paper describes the construction of the control centre for the satellites DFS Kopernikus and TVSAT of the German PTT Administration (DBP Telekom), with emphasis on the implemented technical solutions for monitoring and control. The space and ground segments of the two satellite systems are briefly described in relation to the TT&C operations carried out at the control centre.
We should not pool diagnostic likelihood ratios in systematic reviews
Authors: Zwinderman Aeilko H. , Bossuyt Patrick M. 
Published: July 2007

AbstractSome authors plead for the explicit use of diagnostic likelihood ratios to describe the accuracy of diagnostic tests. Likelihood ratios are also preferentially used by some journals, and, naturally, are also used in meta‐analysis. Although likelihood ratios vary between zero and infinity, meta‐analysis is complicated by the fact that not every combination in ℜ+ is appropriate. The usual bivariate meta‐analysis with a bivariate normal distribution can sometimes lead to positive probability mass at values that are not possible. We considered, therefore, three different statistical models that do not suffer from this drawback. All three approaches are so complicated that we advise to consider meta‐analysis of sensitivity and specificity values instead of likelihood ratios. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of recurrent event data with incomplete observation gaps
Authors: Kim Yang‐Jin , Jhun Myoungshic 
Published: July 2007

AbstractIn analysis of recurrent event data, recurrent events are not completely experienced when the terminating event occurs before the end of a study. To make valid inference of recurrent events, several methods have been suggested for accommodating the terminating event (Statist. Med.1997;16:911–924;Biometrics2000;56:554–562). In this paper, our interest is to consider a particular situation, where intermittent dropouts result in observation gaps during which no recurrent events are observed. In this situation, risk status varies over time and the usual definition of risk variable is not applicable. In particular, we consider the case when information on the observation gap is incomplete, that is, the starting time of intermittent dropout is known but the terminating time is not available. This incomplete information is modeled in terms of an interval‐censored mechanism. Our proposed method is applied to the study of the Young Traffic Offenders Program on conviction rates, wherein a certain proportion of subjects experienced suspensions with intermittent dropouts during the study. Copyright © 2007 John Wiley & Sons, Ltd.
Countercurrent distribution studies on fat soluble plant pigments
Authors: Lancaster Catherine R. , Lancaster Earl B. , Dutton Herbert J. 
Published: July 2007

SummaryChlorophyll‐a, chlorophyll‐b, and carotene have been used to study the operation of countercurrent distribution apparatus. An incomplete separation of the chlorophylls was obtained by the use of the 25‐tube Craig apparatus, but nearly complete separation of the chlorophyll and carotene pigments resulted. Degree of separation can be estimated by the modification of the equation of Martin and Synge which follows:
urn:x-wiley:0003021X:media:aocs0386:equation:aocs0386-math-0001
Comparisons were made between the degree of separation predicted by these formulae and that calculated by the use of the binomial expansion. The utility of such predictions is illustrated by the problem of separating plant pigments. A nomographic solution of these equations is presented to facilitate their application.
Continuous ultrasonic hydrogenation of soybean oil. II. Operating conditions and oil quality
Authors: Moulton K. J. , Koritala S. , Warner K. , Frankel E. N. 
Published: July 2007

AbstractIn previous work we found that ultrasonic energy greatly enhanced the rate of hydrogenation of soybean oil. We have now investigated parameters of ultrasonic hydrogenation and the quality of the resulting products. Refined and bleached soybean oil was hydrogenated continuously with and without ultrasonic energy at different temperatures, pressures and catalyst concentrations. Flavor and oxidative stability of the oils were compared with a commercially hydrogenated soybean oil. The extent of hydrogenation (ΔIV) was not affected by temperature between 245 and 290 C, but was greater at 106 psig than at 65 psig hydrogen pressure. The ΔIV of hydrogenated oils increased linearly with catalyst concentration from 40 ppm to 150 ppm nickel. At the same catalyst concentration the IV drop was significantly increased when ultrasonic energy was used. By reducing the amount of power supplied to the ultrasonic reactor to 40% of full power, the specific power (watts/ΔIV) was lowered by 60%. Linolenate selectivities and specific isomerization (%trans/ΔIV) remained the same, but linoleate selectivities were lower than for batch hydrogenation under varied operating parameters. Flavor scores were not significantly different, initially or after storage eight days at 60 C, for oils continuously hydrogenated with and without ultrasonic energy. Hydrogenation of soybean oil with ultrasonic energy offers a method to produce good quality products at potentially lower cost than present methods.
The use of atomic force microscopy to measure the formation and development of chocolate bloom in pralines
Authors: Smith Paul R. , Dahlman Annika 
Published: July 2007

AbstractAtomic force microscopy (AFM) has been used to study the surface of chocolate as well as the progress of chocolate bloom over time. Fresh chocolate was found to be relatively smooth but with deep holes. These could be pipes leading deep down into the body of the chocolate, perhaps reaching the filling. After storage for a few weeks, we observed the growth of small drops around these holes. With increasing time, these drops became larger and more structured. After further storage, a crystalline structure and bloom were revealed. These results suggest that bloom growth in pralines is a two‐phase process, with drops initially forming on the surface and then bloom crystals nucleating and growing from them. Further, we deduced pipes leading down into the center of the chocolate through which the migration of filling fats can preferentially occur.
Recovery of corn oil from ethanol extracts of ground corn using membrane technology
Authors: Kwiatkowski Jason R. , Cheryan Munir 
Published: July 2007

AbstractThe recovery of additional co‐products from the dry‐grind process for ethanol could influence the industry greatly, as most facilities today rely on subsidies and tax incentives to operate. Modification of the process to include the extraction of oil could add $0.30–0.50 per bushel to the value derived from corn. A process combining solvent extraction with membrane technology to recover the oil was investigated. To evaluate the feasibility of this process, several nanofiltration membranes were tested for their stability in ethanol. Each of the membranes was conditioned with a solution of water/ethanol (0–100 vol/vol%) and the top three were chosen based on their performance with respect to flux and rejection. Beginning at 5 g/L, solutions of corn oil in ethanol were concentrated to over 100 g/L with the DK (Osmonics‐Desal, Minnetonka, MN), TFC‐SR1 (Koch Membrane Systems, Inc., Wilmington, MA) and TFC‐SR2 (Koch) membranes. The liquid extract was then similarly concentrated, yielding a retentate fraction that was highly concentrated with solids in addition to corn oil, such as protein (zein), lecithins, and other potentially high‐value fractions soluble in ethanol. Analysis of the extract retentate showed a significant increase in oil concentration with an increase in the volume concentration ratio, indicating that pure ethanol extracts from corn may be successfully concentrated using nanofiltration membranes.
Severely impaired left ventricular function: Tissue characterization by cardiovascular magnetic resonance in a clinical dilemma
Authors: Bucciarelli‐Ducci Chiara , Locca Didier , O'Hanlon Rory , Oldershaw Paul , Prasad Sanjay K. 
Published: July 2007

AbstractIn patients with symptoms of heart failure, identifying the underlying cause of cardiomyopathy is helpful to establish the diagnosis and to guide therapy. The differential diagnosis of cardiomyopathy can be challenging based on clinical findings. We report the case of a patient who represented a clinical dilemma (cardiac sarcoidosis or ischaemic heart disease), in whom cardiovascular magnetic resonance was a clinically valuable tool to distinguish dual cardiac pathology due to its unique, non‐invasive, tissue characterization capabilities.
Horizontal transmission success of Nosema bombi to its adult bumble bee hosts: effects of dosage, spore source and host age
Authors: RUTRECHT S. T. , KLEE J. , BROWN M. J. F. 
Published: July 2007

SUMMARYParasite transmission dynamics are fundamental to explaining the evolutionary epidemiology of disease because transmission and virulence are tightly linked. Horizontal transmission of microsporidian parasites, e.g. Nosema bombi, may be influenced by numerous factors, including inoculation dose, host susceptibility and host population heterogeneity. Despite previous studies of N. bombi and its bumble bee hosts, neither the epidemiology nor impact of the parasite are as yet understood. Here we investigate the influence N. bombi spore dosage (1000 to 500 000 spores), spore source (Bombus terrestris and B. lucorum isolates) and host age (2- and 10-day-old bees) have on disease establishment and the presence of patent infections in adult bumble bees. Two-day-old bees were twice as susceptible as their 10-day-old sisters, and a 5-fold increase in dosage from 100 000 to 500 000 spores resulted in a 20-fold increase in the prevalence of patent infections. While intraspecific inoculations were 3 times more likely to result in non-patent infections there was no such effect on the development of patent infections. These results suggest that host-age and dose are likely to play a role in N. bombi's evolutionary epidemiology. The relatively low levels of horizontal transmission success are suggestive of low virulence in this system.
Planning domain definition using GIPO
Authors: SIMPSON R. M. , KITCHIN D. E. , McCLUSKEY T. L. 
Published: July 2007

AbstractIn this paper an object-centric perspective on planning domain definition is presented along with an overview of GIPO (graphical interface for planning with objects), a supporting tools environment. It is argued that the object-centric view assists the domain developer in conceptualizing the domain’s structure, and we show how GIPO enables the developer to capture that conceptualization at an appropriate and matching conceptual level. GIPO is an experimental environment which provides a platform for exploring and demonstrating the range and scope of tools required to support the knowledge engineering aspects of creating and validating planning systems, both for classical pre-condition planning and hierarchical planning. GIPO embodies the object-centric view, leading to a range of benefits typically associated with object-oriented methods in other fields of software engineering such as highly visual development methods, code reuse and efficient, reliable development.
ARMS: an automatic knowledge engineering tool for learning action models for AI planning
Authors: WU KANGHENG , YANG QIANG , JIANG YUNFEI 
Published: July 2007

AbstractWe present an action model learning system known as ARMS (Action-Relation Modelling System) for automatically discovering action models from a set of successfully observed plans. Current artificial intelligence (AI) planners show impressive performance in many real world and artificial domains, but they all require the definition of an action model. ARMS is aimed at automatically learning action models from observed example plans, where each example plan is a sequence of action traces. These action models can then be used by the human editors to refine. The expectation is that this system will lessen the burden of the human editors in designing action models from scratch. In this paper, we describe the ARMS in detail. To learn action models, ARMS gathers knowledge on the statistical distribution of frequent sets of actions in the example plans. It then builds a weighted propositional satisfiability (weighted SAT) problem and solves it using a weighted MAXSAT solver. Furthermore, we show empirical evidence that ARMS can indeed learn a good approximation of the finally action models effectively.
Parallel arterial trunks with discordant atrioventricular and concordant ventriculo-arterial connections in mirror-imaged arrangement
Authors: Ozkutlu Suheyla , Alehan Dursun 
Published: July 2007

AbstractCardiac malformations are very rare in which the great arteries arise from their appropriate ventricles, but are abnormally related to each other. Here, we present a patient with mirror-imaged atrial arrangement and a left-sided heart who has parallel arterial trunks with discordant atrioventricular and concordant ventriculo-arterial connections. The ventricles were related in supero-inferior fashion, the left ventricle being anterior and superior, this being an additional feature which, to the best of our knowledge, has not previously been described in this setting.
Can working conditions explain differences in eating patterns during working hours?
Authors: Raulio Susanna , Roos Eva , Mukala Kristiina , Prättälä Ritva 
Published: July 2007

AbstractObjectiveThe aim of this study was to examine whether there are associations between working conditions and the use of staff canteen or packed meals among Finnish employees.SettingData were obtained from cross-sectional surveys on working conditions, conducted triennially (1997, 2000, 2003) since 1997.SubjectsIn each survey, the subjects were 25–64-year-old employed Finnish employees: 3096 men and 3273 women.ResultsEmployees at large workplaces used canteens far more often than those at smaller workplaces. Working conditions played a different role in canteen use at small and large workplaces, as well as among the different sexes. At small workplaces, physically demanding jobs held by female employees and low job control encouraged employees to use the canteen. On the other hand, at large workplaces, low social support at work encouraged the use of canteens among men whereas high mental strain at work meant they used the canteen less. Among women, eating packed meals was not related to working conditions, but among men, low social support and high mental strain at work were associated with more frequent use of packed meals.ConclusionsThe use of a staff canteen is largely determined by the size of the workplace and by employee education. The underlying factor could be the availability of canteens, a question which must be confirmed in further studies, since well-planned mass catering at workplaces has major effects on public health, well-being and the nutrition education of employees.