bluuebunny/crossref_metadata_2025_split huggingface dataset:
Systems thinking and thinking systems
Authors: Ackoff Russell L. 
Published: July 2007

AbstractThree types of system are identified and differentiated: mechanical, organismic, and social systems. The evolution of our concept of an enterprise from mechanical to social is then traced, as enterprises are viewed from each of these perspectives. Some consequences of conceptualizing them as social systems are then discussed, including the consequences of (1) considering the parts of an enterprise separately, as is commonly done, that is, managing analytically versus synthetically; (2) supervising personnel who can do their jobs better than their bosses; (3) treating problems separately rather than systemically, and (4) taking disciplines as aspects of reality, that is, as categories of nature.
Critical systems thinking: Beyond the fragments
Authors: Jackson Mike C. 
Published: July 2007

AbstractThis article is concerned with systems thinking as an approach to the management of complex problems. I argue that systems thinking is currently failing to make the most of the significant steps forward taken in the discipline during the 1970s and 1980s. Systems thinking should be able to present itself as the discipline capable of offering a holistic response to a very wide range of management problems. Instead, different groupings of academics and practitioners lay claim to the systems label but share little overall intellectual vision. While the discipline remains fragmented, the claim to offer a holistic and comprehensive response to management problems will seem hollow. Critical systems thinking is suggested as a way for the discipline to progress beyond the fragmentation.
Terminal conditions in system dynamics
Authors: Kivijärvi Hannu , Soismaa Margareta 
Published: July 2007

AbstractWhen developing system dynamics models, particularly in economics and finance, we have repeatedly encountered requirements to analyze terminal conditions. We believe that this holds more generally for modeling social problems, too. In this article, we show how to solve system dynamics models when some level variables have predetermined terminal conditions. With the method presented, it is possible to determine consistently the initial states of the level variables given the terminal state conditions.
Measurement of fetal urine production by three‐dimensional ultrasonography in normal pregnancy
Authors: Lee S. M. , Park S. K. , Shim S. S. , Jun J. K. , Park J. S. , Syn H. C. 
Published: July 2007

AbstractObjectivesMeasurement of fetal urine production may provide a means of evaluating amniotic fluid volume, which is difficult to measure directly, and predicting fetal hypoxia. Although there have been some reports on fetal urine production, most of these have used two‐dimensional (2D) ultrasonography to measure bladder volume. Three‐dimensional (3D) ultrasonography is, however, known to be superior to 2D ultrasonography in some organ volume measurements. Thus, we undertook this study to measure bladder volumes using 3D ultrasonography and to establish a nomogram of fetal urine production rate (UPR) according to gestational age (GA).MethodsOne hundred and fifty‐four women with a normal singleton pregnancy at 24 to 40 weeks' gestation were enrolled in this cross‐sectional study. The women had no medical or obstetric complications affecting amniotic fluid volume. Fetal bladder volume was measured using 3D ultrasound imaging and Virtual Organ Computer‐aided AnaLysis (VOCAL) with a rotational angle of 30 degrees and manual surface tracing technique. Bladder volume was measured two or three times within a 5–10‐min interval and fetal UPR was calculated from serial measurements. When measurements were performed more than twice, we used the mean rate of calculated UPRs. UPR was then plotted against GA to establish the nomogram.ResultsFetal UPR increased with GA from a median value of 7.3 mL/h at 24 weeks' gestation to 71.4 mL/h at term, and could be calculated from GA using the formula: Ln(UPR) = − 6.29582 + (0.43924 × GA) + (0.000432 × GA2), r2 = 0.63, P = 0.0046. Growth percentiles of UPR according to age are presented.ConclusionsFetal UPR can be easily measured by 3D ultrasound assessment of bladder volume. This modality may be a promising alternative to conventional methods of amniotic fluid volume measurement such as amniotic fluid index and single deepest pocket, and might be an alternative option for predicting fetal hypoxia. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Geographical structure of dengue transmission and its determinants in Thailand
Authors: NAGAO Y. , SVASTI P. , TAWATSIN A. , THAVARA U. 
Published: July 2007

SUMMARYExpansion of dengue has been attributed to urbanization. To test this concept, we examined dengue transmission intensities in Thailand. We used the inverse of mean age of dengue haemorrhagic fever (DHF) cases as a surrogate of dengue transmission intensity (or force of infection). The transmission intensity in Bangkok decreased rapidly since the mid-1990s, to levels that are currently lower than in other regions. Regression analysis revealed that transmission intensity is highest in the Northeastern rural region, mainly due to scarcity of private water wells. Private wells reduce the need for household water containers, the major breeding sites for vectors. Cumulatively, these results show that urbanization is not necessarily associated with intense dengue transmission in Thailand. Paradoxically, the DHF incidence in Bangkok has surpassed other regions despite declines in transmission intensity. This finding implies the existence of endemic stability (i.e. low incidence of a clinical illness in spite of high transmission intensity).
Using SIM for Double Star Astronomy
Authors: Shao Michael 
Published: July 2007

AbstractThe SIM (Planet Quest) mission is a space-based long-baseline stellar interferometer designed for ultra-precise astrometry. This paper describes how SIM can be used for double star research. There are several regimes of operation. For binary stars separated by more than 1″.5, SIM treats these as distinct objects. Double stars less than ∼10 milliarcsec in separation are seen as a single object and SIM measures the photocenter of the composite object. Between 10 mas and 1″.15, SIM is able to see the double star as two distinct objects, but because photons from both stars are detected there is the possibility of increased noise and measurement bias. This paper describes how double stars are observed with SIM and what information can be derived.
Modern Analysis Techniques for Spectroscopic Binaries
Authors: Hensberge Herman , Pavlovski Krešimir 
Published: July 2007

AbstractTechniques to extract information from spectra of unresolved multi-component systems are revised, with emphasis on recent developments and practical aspects. We review the cross-correlation techniques developed to deal with such spectra, discuss the determination of the broadening function and compare techniques to reconstruct component spectra. The recent results obtained by separating or disentangling the component spectra is summarised. An evaluation is made of possible indeterminacies and random and systematic errors in the component spectra.
Detecting Chromospheric Activity on the Secondary Star of Cataclysmic Variables
Authors: Kafka Styliani 
Published: July 2007

AbstractChromospheric activity on the secondary stars of cataclysmic variables (CVs) is a key ingredient for angular momentum loss from the system via magnetic braking. This effect is thought to drive the evolution of the system and is invoked to explain a number of observed properties of CV light curves, such as long-term modulations and high/low states. However, obtaining observational support for magnetic activity has proven difficult. We present a new method of studying chromospheric activity on the secondary stars of CVs, using near-IR spectral features. We discuss in particular the magnetic CV AM Herculis, in which satellites to the H-alpha emission line are interpreted as arising from magnetically confined gas streams (prominences). This phenomenon provides a new technique for mapping magnetic structures on CV secondaries, and advances our understanding of the nature of magnetic structures and activity on CV secondaries.
The Apsidal Motion Test in Eclipsing Binaries
Authors: Giménez Alvaro 
Published: July 2007

AbstractThe use of eccentric eclipsing binaries to test stellar internal structure models, as well as the equations of motion provided by General Relativity, is reviewed. Close to 80 years have elapsed since the first ideas were produced in this field and many results have been obtained since then. It appears that, in general, a good understanding of stellar structure within the main sequence is available while the same level of knowledge can not be claimed beyond the termination age. The equations of general relativity could not be disproved with observational data though some systems cannot still be fully explained. In the near future, the analysis of evolved systems, very low mass stars, the effects of tidal resonances and the presence of third bodies has to be further explored. In addition, the analysis of large data bases obtained by means of extensive photometric surveys will certainly change the picture from an observational point of view.
The Sun's Smaller Cousins are Running the Universe — The Masses of Red and Brown Dwarfs
Authors: Henry Todd J. 
Published: July 2007

AbstractAlthough not one red dwarf can be seen with the naked eye, they dominate the solar neighborhood, accounting for no less than 70% of all stars. The large numbers of these wee denizens of the night actually translate into a surprisingly large amount of mass – in fact, more mass is found in M dwarfs than in any other stellar spectral type.To determine just how important red dwarfs are to the nature of the Universe, an accurate mass-luminosity relation (MLR) must be determined so that a relatively easily determined characteristic, luminosity, can be converted into the critical parameter, mass. Results from a decade-long observational effort to calibrate the MLR for red dwarfs using the Fine Guidance Sensors (FGSs) on the Hubble Space Telescope (HST) will be highlighted. For many of the binary systems targeted, the interferometric data from HST are combined with radial velocity data to further improve the mass measurements, which often have errors less than 5%. Related results from a large southern sky parallax program to determine accurate distances to red dwarfs, and a search for companions orbiting them, will also be discussed.The state of mass determinations for M dwarfs' smaller cousins, the L and T dwarfs, will also be reviewed. Although we do not yet know the size of the true population of these (primarily) substellar objects, only by mapping out the interplay of their masses and luminosities (which change drastically with time) can we understand their contribution to the mass budget of the Universe.
U Geminorum: a Test Case for Orbital Parameters Determination
Authors: Echevarría Juan , de la Fuente Eduardo , Costero Rafael 
Published: July 2007

AbstractHigh-resolution spectroscopy of U Gem was obtained during quiescence. We did not find a hot spot or gas stream around the outer boundaries of the accretion disk. Instead, we detected a strong narrow emission near the location of the secondary star. We measured the radial velocity curve from the wings of the double-peaked Hα emission line, and obtained a semi-amplitude value in excellent agreement with the ultraviolet results by Long & Gilliland (1999). We present also a new method to obtain K2, which enhances the detection of absorption or emission features arising in the late-type companion. Our results are compared with published values derived from the near-infrared NaI line doublet. From a comparison of the TiO band with those of late type M stars, we find that a best fit is obtained for a M6 V star, contributing 5% of the total light at that spectral region. Assuming that the radial velocity semi-amplitudes reflect accurately the motion of the binary components, then from our results: Kem = 108 ± 2 km s−1; Kabs = 310 ± 5 km s−1, and using the inclination angle by Zhang & Robinson (1987); i = 69°.7 ± 0.7, the system parameters become: MWD = 1.20 ± 0.05 M⊙; MRD = 0.42 ± 0.04 M⊙; and a = 1.55 ± 0.02 R⊙. Based on the separation of the double emission peaks, we calculate an outer disk radius of Rout/a ∼ 0.63, close to the distance of the inner Lagrangian point L1/a ∼ 0.63. Therefore we suggest that, at the time of observations, the accretion disk was filling the Roche-Lobe of the primary, and that the matter leaving the L1 point was colliding with the disc directly, producing the hot spot at this location. Specific details not included in the printed version can be found in the Electronic Poster (EP).
Observed Orbital Eccentricities
Authors: Abt Helmut A. 
Published: July 2007

AbstractThe eccentricities of catalogued binaries show that tidal interactions extend to periods of at least 1000 days. The maximum periods for complete circularization probably depend on age, rather than mass. For the longest periods all eccentricities are equally probable. For shorter periods the highest eccentricities disappear first. For the same periods, the SB2's have larger mean eccentricities than the SB1's, in accord with Keplers Third Law.
Asteroseismology of Close Binary Stars
Authors: Aerts Conny 
Published: July 2007

AbstractIn this review paper, we summarise the goals of asteroseismic studies of close binary stars. We first briefly recall the basic principles of asteroseismology, and highlight how the binarity of a star can be an asset, but also a complication, for the interpretation of the stellar oscillations. We discuss a few sample studies of pulsations in close binaries and summarise some case studies. This leads us to conclude that asteroseismology of close binaries is a challenging field of research, but with large potential for the improvement of current stellar structure theory. Finally, we highlight the best observing strategy to make efficient progress in the near future.
Discovery of Four β Cephei Stars in Eclipsing Systems
Authors: Pigulski Andrzej , Pojmański Grzegorz 
Published: July 2007

AbstractUsing the ASAS-3 photometry, we find the components of four eclipsing binary systems — V916 Cen, HD 101838, V4386 Sgr and HD 168050 — to be β Cephei-type pulsators. The first two systems are members of the young open cluster Stock 14. The pulsating stars are presumably the primary, more massive components in all these systems. The components are detached and for at least two systems, V916 Cen and HD 168050, we may suspect that they will appear to be double-lined spectroscopic ones. In consequence, these stars become very attractive targets for studying pulsations in β Cephei stars by means of asteroseismology.
Comparative microbiota ofRickettsia felis-uninfected and -infected colonized cat fleas,Ctenocephalides felis
Authors: Pornwiroon Walairat , Kearney Michael T , Husseneder Claudia , Foil Lane D , Macaluso Kevin R 
Published: July 2007

AbstractFleas serve as arthropod vectors for several emerging and re-emerging infectious disease causing agents including, Rickettsia felis. Although the prevalence of R. felis infection in colonies of fleas has been examined, the influence of the R. felis infection on flea microbiota has not been investigated. We identified three colonies of cat fleas, Ctenocephalides felis, with varying prevalence of R. felis infection (Louisiana State University (LSU), 93.8%; Professional Laboratory and Research Services Inc. (PLRS), 16.4%; Elward II (EL), 0%) and subsequently utilized polymerase chain reaction amplification, restriction fragment length polymorphism analysis and sequencing of the 1.4-kb portions of 16S rRNA genes to examine the diversity of bacteria in the flea populations. A total of 17 different bacterial 16S rRNA gene sequences were identified among the C. felis colonies. The prevalence of two Wolbachia species that were identified in each flea colony differed between colonies and R. felis-uninfected and -infected fleas. Species richness was unchanged among the R. felis-uninfected (LSU, PLRS and EL colonies) and -infected (LSU and PLRS colonies) fleas; however, between R. felis-uninfected and -infected fleas within both the LSU and PLRS colonies, R. felis-uninfected fleas have greater species richness. Diversity indices did not identify a difference in diversity between any of the flea samples. The interaction of endosymbionts within arthropods can widely impact the dissemination of vertically transmitted pathogenic bacteria; and the reciprocal may be true. These results suggest that carriage of R. felis has an impact on the richness of flea microbiota.
Multi-site precipitation downscaling via an expanded conditional density network
Authors: Cannon Alex 
Published: July 2007

AbstractStatistical downscaling models are used to estimate weather data at a station or stations based on atmospheric circulation data defined at a coarser resolution, for example gridded outputs from a Global Climate Model (GCM). Downscaled data can be used as inputs to environmental models that require finer-scale climate fields than are currently available from GCMs. Maintaining realistic downscaling relationships between sites and variables is particularly important in hydrological models, as streamflow depends strongly on the spatial distribution of precipitation in a watershed and on interactions with temperature that determine whether precipitation falls as rain or snow. More generally, precipitation is a difficult variable to downscale because of its non-normal distribution and its spatial and temporal patchiness.A downscaling algorithm for daily precipitation series at multiple stations is presented. The expanded conditional density network (ECDN) models the conditional density of the Poisson-gamma distribution via an artificial neural network. ECDN is capable of (1) specifying the conditional distribution of precipitation at each site; (2) modeling occurrence and amount of precipitation simultaneously; (3) reproducing observed spatial relationships between sites; (4) randomly generating synthetic precipitation series; and (5) predicting precipitation amounts in excess of those in the observational record. The ECDN model is applied to two downscaling problems: the first is a benchmark precipitation downscaling task previously evaluated by other modeling groups; the second is a multi-site precipitation dataset from British Columbia, Canada. Results suggest that the ECDN approach is capable of generating spatially and temporally realistic precipitation series that are suitable for use as inputs to hydrological models or to spatial interpolation schemes.
First Report of Pythium intermedium Causing Root Rot on Rosa canina Rootstock in France
Authors: Metzger R. , Belbahri L. , Calmin G. , Badin N. , Lefort F. 
Published: July 2007

Old cultivars of roses (Rosa spp.) established on Rosa canina as rootstock are grown in field collections in the repository at Gaillard in eastern France, close to the Swiss border. During June 2005 and July 2006, several rose plants in full vegetation were severely wilted, leading ultimately to plant death. Necrotic lesions were present on the roots, and marginal tissue was excised and incubated in the dark at 20°C on PARP V8 agar plates (1). Similar isolates were obtained in both years, which were inoculated within 4 days on V8 agar medium and incubated at 25°C. The pathogen colonies grew approximately 30 mm daily on V8 agar. Colonies on corn meal agar (CMA) (1) were submerged, with or without a vague radiate pattern on potato carrot agar. Main hyphae were as much as 7 μm wide. Sporangia and zoospores were not produced. Hyphal swellings as much as 25 μm in diameter were abundant, terminal, and sometimes intercalary, often forming regular, dense chains in basipetal succession at hyphal tips and readily liberated. The morphological characters matched those described for Pythium intermedium (2). DNA sequencing of the ITS rDNA (ITS1, ITS2, and 5.8S rDNA) was generated using primers ITS5 and ITS4 in primary PCR (35 cycles: 96°C for 1 min, 55°C for 1 min, and 72°C for 2 min) and sequencing reactions (1). All isolates yielded identical ITS sequences, which were identical to the ex-type strain of P. intermedium, CBS 266.38 (GenBank Accession No. AY598647). The ITS sequence was deposited as GenBank Accession No. EF078693 (National Center for Biotechnology Information, NCBI, Bethesda, MD). Pathogenicity testing was performed on 3-year-old Rosa canina rootstocks from clonal propagation in 25 cm in diameter and 40 cm deep pots of compost 297 (Ricoter, Aarberg, Switzerland). Five-day-old mycelial plugs of our isolates grown on CMA (1) were inoculated in two pots, and roots were mechanically wounded. Sterile plugs were used on two control plants set aside. All plants were kept for 2 weeks at 20°C in a glasshouse with sufficient watering. Extensive necrotic lesions developed on inoculated roots, and severe wilting and leaves drying out were also observed. The controls showed no symptoms. P. intermedium was reisolated from margins of root lesions, thus fulfilling the postulates of Koch. P. intermedium was originally isolated from dead plant material (2) but is known as a typical soil inhabitant. It also has been isolated from water and living material from numerous plant species, but never from the genus Rosa until now. To our knowledge, this is the first record of P. intermedium on Rosa spp. grafted on Rosa canina in France. References: (1) L. Belbahri et al. FEMS Microbiol Lett 255:209, 2006. (2) A. J. van der Plaats-Niterink. Stud. Mycol. 21:1, 1981.