bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of basic system parameters of communication networks based on low earth orbit satellites
Authors: Böttcher A. , Jahn A. , Lutz E. , Werner M. 
Published: July 2007

AbstractCurrently many efforts are undertaken to develop and install communication networks based on low earth orbit (LEO) and intermediate circular orbit (ICO) satellites. However, many problems are to be solved until the final operation of such networks. This paper deals with basic design problems of LEO/ICO‐based networks. In the first part, estimates for the necessary number of satellites, orbits and number of communication channels per satellite are derived. Since the latter is a crucial quantity, the number of communication links and channels per link are derived with a more elaborate model in the second part of the paper. This includes the radio links from the satellites to mobile users and to gateways, as well as intersatellite links and terrestrial lines. We introduce a formal model for LEO/ICO‐based networks and propose a method for the evaluation of link capacities, given the network topology and the traffic requirements. As an example, two constellations are investigated in detail. One of these constellations is the IRIDIUM system proposed by Motorola.
Precision waveform shaping and precompensation for high data rate space communications systems
Authors: Tague John A. , Shimoda Lisa M. 
Published: July 2007

AbstractThis paper studies a memory‐based pulse shaping and travelling wave tube precompensation technique applied to high data rate satellite communications. Baseband I and Q waveforms are synthesized from data stored in a distributed arithmetic architecture. The waveforms are adjusted to minimize intersymbol interference, spectral bandwidth and travelling wave tube distortion. We evaluate its performance in a simulated BPSK link. The results show that memory‐based precompensation has great potential to improve link performance.
On the performance and complexity of A generalized minimum distance reed–solomon decoding algorithm
Authors: Peile R. E. 
Published: July 2007

AbstractThe article reports on the characteristics of an algorithm that implements generalized minimum distance (GMD) decoding of Reed‐Solomon codes. The algorithm uses the novel Welch‐Berlekamp (WB) algorithm, as modified by Tze‐Hua, in order to minimize the complexity of the decoder. Both the WB algorithm and the GMD extension of the WB algorithm are described in outline. The performance of the GMD algorithm was simulated on AWGN channels and fading channels. Results are presented both for RS and concatenated RS codes. The gains over conventional decoding are larger for fading channels than for AWGN conditions but seem useful in all cases. The complexities of the GMD algorithm and the WB algorithm are analysed and compared to that of conventional RS decoding algorithms.
GPS synchronized power system phase angle measurements
Authors: Wilson Robert E. , Sterlina Patrick S. 
Published: July 2007

AbstractBefore a major new 500 kV transmission line was placed in service between Oregon and the San Francisco, California area, a series of high‐voltage short circuit tests were performed on the transmission system. The short circuit faults produced a brief ‘delta function’ shock to the regional power system. This paper discusses the use of Global Positioning System (GPS) synchronized equipment for the measurement and analysis of key power system quantities.Before the testing, the authors installed two GPS synchronized phasor measurement units (PMUs). The PMUs use GPS to globally synchronize the measurement of the state vector of the power system, the complex voltages of substation busses. Complex voltage means the magnitude and the relative phase angles of substation voltages. GPS provides the global time reference marker for phase angle measurement. One electrical degree of the 60 Hz waveform equals about 46 μs. Across short transmission lines (less than 50 km), measurements may need to be made to 0.1 electrical degree, which translates to clock synchronizations of roughly 5 μs.The PMUs recorded the dynamic response of the power system phase angles when the northern California power grid was excited by the artificial short circuits. Power system planning engineers perform detailed computer generated simulations of the dynamic response of the power system to naturally occurring short circuits, e.g. faults caused by lightning. The computer simulations use models of transmission lines, transformers, circuit breakers, and other high voltage components. This work will compare computer simulations of the same event with field measurements.
The role of vsat systems in broadband networks and intelligent networks
Authors: Ananasso Fulvio , Verde Giorgio Lo 
Published: July 2007

AbstractThe scope of this paper is to present the status and the preliminary results of the research activities that Telespazio is carrying out with the aim at identifying the role of the VSAT systems in the advanced telecommunications services, which will be dominant in the second half of nineties and beyond. The first part of the paper is devoted to an overview of the evolution trend of the terrestrial networks. The main body of the paper presents the results of our investigations on the application of VSAT systems in two fields: broadband networks and intelligent networks. Background information has been intentionally added for the easier comprehension of the topics presented in the paper. A list of acronyms appears as an Appendix.
The italsat satellite system
Authors: Carducci F. , Francesi M. 
Published: July 2007

AbstractIn 1995 the second flight unit of ITALSAT telecommunication satellite will be ary orbit, making operative the ITALSAT telecommunication system after the experimental and preoperational phase performed by ITALSAT F1, which was launched in January 1991 by the Italian Space Agency.A general view of the ITALSAT system is presented with emphasis on the satellite design, the telecommunication mission, the new technologies and the prospects.
Performance of cofdm for satellite digital audio broadcasting
Authors: Franchi A. , Colzi E. , Elia C. , Harris R. A. 
Published: July 2007

AbstractThis paper analyses the performance of a coded orthogonal frequency division multiplexing (COFDM) based system for digital audio broadcasting using a highly inclined orbit satellite constellation. The sources of performance degradation considered are non‐linear amplification in the satellite transponder and multipath propagation for mobile reception. Despite its strong peak‐to‐mean amplitude variation, COFDM has been found to be very robust against non‐linear amplification. In the multipath channel, practical cases demonstrate low performance losses even in highly populated areas when highly inclined elliptical orbits (HEO) are used.
Substrate Wetting and Topographically Induced Ordering of Amorphous PI‐b‐PFS Block‐Copolymer Domains
Authors: Roerdink Monique , Hempenius Mark A. , Gunst Ullrich , Arlinghaus Heinrich F. , Vancso G. Julius 
Published: July 2007

AbstractThe substrate wetting of an amorphous, low‐glass‐transition‐temperature spherical poly(isoprene‐block‐ferrocenylsilane) (PI‐b‐PFS) block copolymer and the alignment of the microdomains in grooves of various geometry are studied. Compositional analysis by time‐of‐flight secondary ion mass spectrometry depth profiling (TOF‐SIMS) indicates the presence of both PI and PFS directly at the film–substrate interface on silicon and silica substrates. The TOF‐SIMS depth‐profiling study indicates a transition in the packing of the domains between the two‐dimensional (2D) monolayer and 3D, thicker layers. In a monolayer of domains, a hexagonal packing is adopted. In films of two or three layers, the hexagonal packing reorganizes towards a body‐centered cubic (bcc) packing by the extension of the copolymer chains in the direction normal to the substrate, as indicated by an increase in spacing between PFS layers and an increase in domain size. For thicker layers, a bcc morphology with the (110) plane parallel to the substrate is found to extend from the free surface downwards. Films of one monolayer of domains of the copolymer exhibit long‐range lateral ordering on the micrometer scale on flat substrates without high‐temperature annealing. On topographically patterned silicon substrates the position of the domains of the minority PFS phase directly near the side walls is fixed by the neutral wetting condition. Successful positioning of the block‐copolymer spheres in linear and hexagonal grooves is achieved in grooves up to 1.3 μm wide, whereby the hexagonal grooves demonstrate complete 2D alignment. In circular pits, this graphoepitaxial effect is absent.
Some additional notes on the kinetics and theory of fatty oil hydrogenation
Authors: Bailey A. E. 
Published: July 2007

Summary

Equations are given for estimating from the composition of oil samples the relative reaction rates of the different unsaturated fatty acids in an oil subjected to catalytic hydrogenation.

Application of the equations to data from the hydrogenation of cottonseed oil reveals that the ratio of reaction rates, linoleic acid to oleic acid, varies from about 4 to 1 in very non‐selective to about 50 to 1 in very selective hydrogenation. Re‐examination of analytical data on two series of linseed oils hydrogenated selectively and non‐selectively showed the following relative reaction rates for oleic, isolinoleic (9: 10, 15: 16 octadecadienoic), linoleic, and linolenic acids, respectively: non‐selective, 1, 2.5, 7.5, 12.5; selective, 1, 3.85, 31, 77. In the non‐selective hydrogenation of the oil, 24% of the linolenic acid reacting went to linoleic acid, 65% to isolinoleic acid, and 11% directly to oleic acid. In the selective reaction the corresponding figures were none to linoleic acid, 54% to isolinoleic acid, and 46% to oleic acid. The behavior of soybean oil hydrogenated selectively was quite similar to that of linseed oil.

The results are discussed in relation to the theory of catalytic hydrogenation. They indicate that the solution of hydrogen in the oil and the adsorption of unsaturated oil on the catalyst are the two steps which are controlling with respect to the reaction rate. It is suggested that the hydrogen pressure, the degree of hydrogen dispersion through the oil, the catalyst concentration, and the temperature all affect the selectivity of the reaction through their influence on the concentration of hydrogen in the reaction zone, with selectivity being favored by a low concentration.
Polymerization of styrene with ethyl linoleate
Authors: Dyer Elizabeth , Maxwell Jane L. 
Published: July 2007

SummaryThe emulsion polymerization at 40°C. of mixtures of oxidized ethyl linoleate and styrene with potassium persulfate as catalyst yielded copolymers containing a maximum of one mole of ester per thirteen moles of styrene. A product of similar composition was obtained by bulk polymerization at 80°C.When the amount of ester in the monomer mixture was increased to 50 per cent in the emulsion polymerization, the ester content of the polymer was increased and the molecular weight and yield were decreased.
Determination of free gossypol in cottonseed materials
Authors: Pons Walter A. , Guthrie John D. 
Published: July 2007

SummaryA method for the determination of free gossypol in cottonseed materials is described. The method consists of extraction of gossypol with a measured volume of 70% aqueous acetone on a shaker for one hour, filtration, and colorimetric analysis for gossypol in an aliquot of the filtrate by means of the reaction between gossypol andp‐anisidine.The conditions for complete extraction of gossypol from various types of cottonseed materials have been investigated, the stability of gossypol in aqueous acetone has been demonstrated, and data are presented on recovery of gossypol added to cottonseed materials. The method has been compared with the method of Smith (2).
Naturally occurring epoxy oils1
Authors: Krewson C. F. 
Published: July 2007

AbstractFatty acids containing oxirane functional groups have unexpectedly been found in wide distribution in seed oils, usually present as longchain glycerides. Four such acids have been discovered:cis‐ andtrans‐9,10‐epoxystearic acid; vernolic (cis‐12,13‐epoxyoleic) acid; coronaric acid, isomeric with vernolic acid but with the oxirane and double‐bond functions in the reverse positions; andcis‐15,16‐epoxylinoleic acid. No single analytical tool has been universally successful in measuring the oxirance content of epoxides. This appears to be caused by the way in which the chemical reactivity of the three‐membered cyclic ether is modified by molecular structure and by the presence of nearby substituents.A survey of the published methods for the determination of oxirane functions, including mention of the nature of interfering substances, is given. Techniques used to overcome some of these difficulties are discussed. These procedures include the use of chromatographic and spectrophotometric procedures to solve some of the analytical problems which are encountered. Special consideration is given to vernolic acid and its glycerides since this is the most widely distributed and abundant epoxy acid found in seed oils to date.
The domestic tung industry today
Authors: Potter George F. 
Published: July 2007

AbstractThe tung tree (Aleurites fordii) requires a moderately acid soil, an annual rainfall of 45 to 70 in., and a long hot summer, yet it must have a period of cold weather in winter. These factors limit its culture in North America to a narrow belt along the Gulf of Mexico from Florida to Texas. The majority of the orchards presently consist of miscellaneous seedlings that are about 30 years of age. By replacing these with orchards of new varieties, on suitable soil, and by following recommended practices, growers can produce oil at lower costs than previously. However, crop loss from frost is still a serious problem. Machine harvesting is now a reality. During World War II the government requisitioned the entire domestic production of tung oil for military purposes, and regular customers had to turn to other products. This market has not yet been fully won back, and growers look to utilization research to improve the market.
Pregnancy and perinatal health in Inner Mongolia, China, 1996–1999
Authors: Liu Z. , Lobdell D.T. , Myers S.L. , He L. , Yang M. , Kwok R.K. , Mumford J.L. , Mendola P. 
Published: July 2007

AbstractObjectiveTo obtain descriptive measures of maternal and perinatal health in the Ba Men Region of Inner Mongolia, China.MethodsData collected from the Examination Chart for Pregnant Women for approximately 22,000 pregnancies in a three‐county area of Inner Mongolia, China from December 1, 1996 through December 31, 1999 were analyzed for maternal, perinatal, and neonatal outcomes.ResultsCompared to selected developing countries, a higher percentage of women (99%) in this region received at least one prenatal care visit. This region was also characterized by a low percentage of low birthweight (< 2.5 kg) infants (1%) and neonatal mortality rate (5 deaths per 1000 live births).ConclusionsMaternal and neonatal health outcomes in this region of Inner Mongolia were better than those in selected developing countries.
Understanding and attitudes towards patient safety concepts in obstetrics
Authors: Nabhan A. , Ahmed‐Tawfik M.S. 
Published: July 2007

AbstractObjectives: To measure attitudes of health personnel towards patient safety, and to determine how the concept of patient safety varies between maternal health centers and types of health care personnel. Methods: A cross‐sectional descriptive study included 35 primary heath centers in three governorates in Egypt. The subjects comprised all managers, physicians, nurses, pharmacists, and technicians. Results: The overall mean for all questions and respondents was 3.89 ± 0.59 (scale 1–5). The safety climate mean was 3.64 ± 0.67. The percentage of respondents viewing the safety climate as positive was 36%. Only 7% of respondents had received feedback after referral of a case of severe pre‐eclampsia. Conclusion: The concept of patient safety in the centers studied is not as strong as desirable for the provision of reliable health care. The culture is one of a penalizing nature with suppressed error reporting, lack of proper communication, and feedback failure.
Vertebrate burrows in late pleistocene paleosols at Korean Palaeolithic sites and their significance as a stratigraphic marker
Authors: Lim Hyoun Soo , Lee Yong Il , Yi Seonbok , Kim Cheong-Bin , Chung Chull-Hwan , Lee Heon-Jong , Choi Jeong Heon 
Published: July 2007

AbstractA vertebrate burrow-bearing layer of late Pleistocene age is commonly found at many Paleolithic archaeological sites in Korea. The burrows are straight to slightly curved in horizontal (plan) view and gently inclined in lateral (sectional) view. They are interpreted as having been produced by rodent-like mammals based on their size and architecture. The significance of such burrow-bearing layers as a characteristic stratigraphic marker unit is demonstrated by high burrow abundance, consistent stratigraphic position, lack of stratigraphic recurrence at these sites, and widespread geographic extent. Three dating methods, tephrochronology, radiocarbon, and OSL dating, were used to infer the age of these burrow-bearing layers. The dating results indicate that they were formed between ca. 40,000 and 25,000 yr (MIS 3−2), and this suggests that this layer can be used as a stratigraphic time-marker in late Pleistocene paleosol sequences for this region.
Mechanizing metatheory in a logical framework
Authors: HARPER ROBERT , LICATA DANIEL R. 
Published: July 2007

AbstractThe LF logical framework codifies a methodology for representing deductive systems, such as programming languages and logics, within a dependently typed λ-calculus. In this methodology, the syntactic and deductive apparatus of a system is encoded as the canonical forms of associated LF types; an encoding is correct (adequate) if and only if it defines acompositional bijectionbetween the apparatus of the deductive system and the associated canonical forms. Given an adequate encoding, one may establish metatheoretic properties of a deductive system by reasoning about the associated LF representation. The Twelf implementation of the LF logical framework is a convenient and powerful tool for putting this methodology into practice. Twelf supports both the representation of a deductive system and the mechanical verification of proofs of metatheorems about it. The purpose of this article is to provide an up-to-date overview of the LF λ-calculus, the LF methodology for adequate representation, and the Twelf methodology for mechanizing metatheory. We begin by defining a variant of the original LF language, calledCanonical LF, in which only canonical forms (long βη-normal forms) are permitted. This variant is parameterized by asubordination relation, which enables modular reasoning about LF representations. We then give an adequate representation of a simply typed λ-calculus in Canonical LF, both to illustrate adequacy and to serve as an object of analysis. Using this representation, we formalize and verify the proofs of some metatheoretic results, including preservation, determinacy, and strengthening. Each example illustrates a significant aspect of using LF and Twelf for formalized metatheory.
Influence of antigens and adjuvants on the production of gamma‐interferon and antibody by ovine lymphocytes
Authors: Emery D. L. , Rothel J. S. , Wood P. R. 
Published: July 2007

SummaryThe production of gamma‐interferon (γ‐IFN) and antigen‐specific immunoglobulin isotypes was monitored in sheep given primary and secondary inocula of protein and polysaccharide antigens with or without adjuvants. In efferent lymph from prefemoral nodes draining the site of inoculation, γ‐IFN levels increased within 24 h after injection of adjuvants Quill A, dextran sulfate (DXS) and 6 days after oil adjuvants in saline. The increased synthesis of γ‐IFN was prolonged by 1–2 days by the presence of adjuvanted antigen, but the major stimulus to γ‐IFN production was provided by the adjuvant. Alhydrogel (AH) did not initiate γ‐IFN synthesis. Following a second inocula of antigen in saline, increased levels of γ‐IFN were detected in efferent lymph after 3–4 h, and persisted for at least 2 days. Following cultivation of leucocytes from immunized sheep with specific antigen in vitro, strong positive correlations between levels of interleukin (IL) IL‐2, ‐IFN, proliferative responses and antibody titres were observed. However, after analysis of the antigen‐specific isotypes of immunoglobulin (Ig) there was no correlation between the production of γ‐IFN and particular Ig isotypes. Together with findings that AH did not preferentially induce IgG1 or IgG2, these results suggest that the specific subpopulations of helper T lymphocytes which regulate the production of antibody isotypes by differential secretion of γ‐IFN or IL‐4, are not as clearly defined in sheep as in mice.
Mapping the dextran sulfate binding site on CD2
Authors: Warren Hilary S. , Parish Christopher R. 
Published: July 2007

SummaryThis study has analysed the binding of a series of anti‐CD2 monoclonal antibodies (MoAbs) to T cells in the presence of the sulfated polysaccharide dextran sulfate (2·3 sulfates/monosaccharide, 500 kDa) (DXS) to define the DXS binding site on CD2. The results show that DXS interacts primarily at the T112 epitope. Thus five anti‐CD2 MoAbs which bound to the T112 epitope were inhibited in their binding by DXS. In contrast, seven anti‐CD2 MoAbs that totally inhibited sheep red blood cells (SRBC) rosetting (identifying the T111 epitope) were unaffected in their binding to T cells in the presence of DXS. Three MoAbs which partially inhibited SRBC rosetting and thereby defining only part of the T111 epitope, were also inhibited in their binding by DXS. Consistent with the conclusion that the DXS binding site on CD2 is associated with the T112 epitope was the observation that interaction of DXS with CD2 resulted in augmented binding of the four MoAbs defining the T113 epitope, possibly reflecting an increased expression of the T113 (activation, CD2R) epitope of CD2. Collectively, the data presented support the notion that a natural ligand for the T112 epitope of CD2 will be identified as a sulphated carbohydrate structure.
Antibodies to type II collagen in SLE: A role in the pathogenesis of deforming arthritis?
Authors: Choi Edward K. K. , Gatenby Paul A. , Bateman John F. , Cole William G. 
Published: July 2007

SummaryThe role of autoimmunity to type II collagen in the arthritis of systemic lupus erythematosus (SLE) has been assessed by ELISA and by Western blotting cyanogen bromide cleavage fragments separated on SDS‐PAGE. The results show that antibodies to both native and heat‐denatured collagen are quite common in SLE when measured by ELISA. Of particular interest is the demonstration of an association between antibodies to the CB 11 peptide and deforming arthritis in SLE. This is the arthritogenic peptide in murine models of collagen II‐induced autoimmune arthritis and the results presented here suggest a potential pathogenetic role in the deforming arthritis of SLE for this specific subset of antibodies to type II collagen.