bluuebunny/crossref_metadata_2025 huggingface dataset:
Callose-containing deposits in relation to root-hair infections of Alnus rubra by Frankia
Authors: Berry A. M. , McCully M. E.
Published: April 2009

Light microscopy, aniline-blue fluorescence histochemistry, and transmission electron microscopy were used to elucidate the nature of localized wall deposition in infected and uninfected root hairs on nodulated roots of Alnus rubra Bong, inoculated with the nitrogen-fixing symbiont, Frankia HFPAr13. Callose-containing papillae were found only in epidermal hair cells and not in cortical or vascular tissue. At the site of successful root-hair wall penetration, transfer cell-like wall ingrowths were elaborated, but callose was not detected. At sites of arrested root-hair infections, complex deposits consisting of callose, fibrillar components, and electron-dense material surrounded the incipient hyphal infection. The cytoplasm of root hairs containing arrested infections was deteriorated compared with successfully infected root hairs.
Éléments du contrôle de la morphogenèse de la vigne in vitro: sympodisation
Authors: Fournioux Jean-Claude , Bessis Roger
Published: April 2009

In vitro growth of the grapevine, Vitis vinifera L., may result in the usurping development of the axillary buds at certain nodes and the sympodisation of the shoot. Many theories on the sympodial nature of the branches developped in situ have already been proposed. All these theories seem to be speculative. In this study, the usurpation is not hypothetical. All the morphological facts described here prove its reality. Sympodisation is closely related to tendril formation and occurs only if the young shoots grown in vitro bear tendrils. When present, usurpation is always observed in a node with tendril. Sympodisation is demonstrated by the observation of prefoliar characters and phyllotactic planes, which allow the order of the different planes to be determined. Based on these observations, we formulate a hypothesis to explain this phenomenon. The size of the apical meristem in in vitro conditions being much less than the normal size, a restricted area should remain after the simultaneous formation of a leaf and a tendril. However, if this meristematic residue remains relatively voluminous, the shoot apex may be regenerated. If not, the restoration can not take place and sympodisation will result.
Productivité végétale dans un marais intertidal d'eau douce, Québec (Québec)
Authors: Gilbert Hélène
Published: April 2009

Above- and below-ground annual productivity of vascular plants in the freshwater tidal marsh of the City of Québec (St. Lawrence River) was estimated to be 280 g dry weight/m2. This low productivity is explained in part by the very large surface of bare ground (23%), by the relative importance (39%) of the surface dominated by much less productive aquatic vegetation, and by the presence of embankments on the formerly most productive parts of the marsh. The most productive plant associations were those dominated by Scirpus americanus Pers. (606 g dry weight∙m−2∙a−1), Zizania aquatica L. var. brevis (702), Sagittaria rigida Pursh (598) and Sagittaria latifolia Willd. (834). Species productivities (in g dry weight∙m−2∙a−1) were 436 (Sc. americanus), 196 (Z. aquatica), 86 (Sa. rigida), and 685 (Sa. latifolia). An analysis of the biomass allocation (seasonal pattern) is presented for five species.
Éléments nutritifs (N et P), métaux lourds (Zn, Cu, Pb et Hg) et productivité végétale dans un marais intertidal d'eau douce, Québec (Québec)
Authors: Gilbert Hélène
Published: April 2009

The N and P content in the sediment of the intertidal freshwater marsh of Québec City (St. Lawrence River) was analyzed in relation with the phytomass on the site. The heavy metals (Zn, Cu, Pb, and Hg) content in plants and sediment was also measured and the seasonal and comparative evolution of the concentrations was studied in relation with the biomass and productivity of vascular plants. The variations in NO2–NO3, NH4 and orthophosphate in tidal water between the flood and the ebb were studied. The mass balance of NH4 and orthophosphate in tidal water is positive toward the marsh, but the 5.5 kg/ha NH4 and 5.4 kg/ha PO4 that are trapped on the marsh are considered as low compared with the sediment contribution. Approximately 1323 mg N/kg dry weight and 41 mg P/kg dry weight are assimilated by plants from sediments during the growing season. Plants would actively assimilate Hg, whereas Pb and Zn would be passively absorbed; Cu is more actively assimilated in the roots during the maximum growth period. There is 11.2 times more Hg in the plants than in the sediment. Scirpus americanus contained more Hg than the other species. The rates of incorporation of Zn, Cu, Pb, and Hg in three species are presented.
A taxonomic study of the moss genus Dicranum (Dicranaceae) in Ontario and Quebec
Authors: Bellolio-Trucco Gilda , Ireland Robert R.
Published: April 2009

Specimens of the genus Dicranum (Bryopsida, Dicranaceae) in major herbaria were examined to better understand the taxa present in Ontario and Quebec. A total of 21 species and two varieties are recognized for the two provinces. Dicranum angustum Lindb. is shown to be synonymous with D. spadiceum Zett. Keys, descriptions, illustrations, and distribution maps are provided for the taxa. Diagnostic characters and a discussion of morphological variability is presented for many of the taxa. Key words: Dicranum, Dicranaceae, Bryopsida, Ontario, Quebec, taxonomy, distribution.
Graphical Model of Thermoregulatory Behavior by Fishes with a New Measure of Eurythermality
Authors: Giattina James D. , Garton Ronald R.
Published: April 2009

The behavioral responses of fishes, specifically preference and avoidance reactions, to temperature are described using a general graphical model based on a broad overview of the literature. A quantitative measure of eurythermality, based on the area of the thermal preference zone, is presented which offers a more meaningful estimate of the optimal thermal requirements of the species than one based on lethality alone. We also emphasize the importance of considering the preference–avoidance responses of fishes when setting ambient water quality criteria for temperature or when estimating the potential environmental impact resulting from changes in the thermal regime of an aquatic system.Key words: thermoregulation, behavior, temperature, eurythermality, thermal preference, avoidance
Slope protection along St. Lawrence Seaway canals
Authors: Olpinski K. , Christensen C. J.
Published: April 2009

The St. Lawrence Seaway passes through the St. Lawrence River, the Great Lakes, and three Canadian canals: South Shore and Beauharnois Canals in Quebec, and the Welland Canal across the Niagara Peninsula in Ontario. The varied geological conditions and the continuous growth of navigation traffic through its 150 year history influenced the need for and the type and extent of protection for the canal slopes. The methods used include cut stone, riprap, concrete slabs, grouted riprap, soil–cement, gabions, mattresses filled with mortar slurry, and in special cases armour stone and protective rolls. This paper presents their design, construction, behaviour, and cost, with supporting background information. Riprap has proved, so far, to be the most reliable and economical general slope protection method, since suitable rock materials are still readily available locally.
FOREIGN ENCLAVES, INFORMAL SECTOR AND URBAN UNEMPLOYMENT: A THEORETICAL ANALYSIS
Authors: BANDOPADHYAY TITAS KUMAR
Published: April 2009

We consider a small open Harris-Todaro (1970) economy with a rural foreign enclave and urban informal sector. We introduce consumption-efficiency relation to explain the simultaneous existence of informal sector and urban unemployment. The main objective of this paper is to analyse the effects of removal of subsidy, given to the foreign enclave, on urban unemployment and on domestic factor income. Our results shed light on the debate: whether subsidies should be removed from the agri-export sector.
INVESTIGATION ON THE PHYSICOCHEMICAL PROPERTIES OF NONLINEAR OPTICAL SINGLE CRYSTAL: 2-NAPHTHALENOL
Authors: SELVARAJU K. , KIRUBAVATHI K. , KUMARARAMAN S.
Published: April 2009

Single crystals of 2-Naphthalenol (2N), new organic nonlinear optical (NLO) material, have been grown by slow evaporation solution growth technique at room temperature. The crystal system has been confirmed from the single crystal X-ray diffraction analysis. The functional groups were identified using FTIR spectroscopy. UV-vis-NIR spectrum showed absence of absorption in the wavelength region 400–1400 nm. The second harmonic generation efficiency is two times higher than that of standard potassium dihydrogen phosphate (KDP).
INFLUENCE OF GROWTH RATE ON MICROSTRUCTURE AND MICROINDENTATION HARDNESS OF DIRECTIONALLY SOLIDIFIED TIN–CADMIUM EUTECTIC ALLOY
Authors: ÇADIRLI E. , KAYA H. , GÜNDÜZ M.
Published: April 2009

Sn – Cd eutectic melt was first obtained in a hot filling furnace and then directionally solidified upward with different growth rate ranges (8.1–165 μm/s) at a constant temperature gradient G (4.35 K/mm) in the Bridgman-type directional solidification furnace. The lamellar spacings (λ) were measured from both transverse and longitudinal sections of the samples. The influence of the growth rate (V) on lamellar spacings (λ) and undercoolings (Δ T) was analyzed. λ2V, ΔTλ and ΔTV-0.5 values were determined by using λ,ΔT and V values. Microindentation hardness (HV) was measured from both transverse and longitudinal sections of the specimens. HV values increase with the increasing values of V but decrease with increasing λ values. λ-V, λ - ΔT and λ2V results have been compared with the Jackson–Hunt eutectic model and similar experimental results, HV - V and HV - λ results were also compared with the previous work.
MEASUREMENTS OF SOLID–LIQUID INTERFACIAL ENERGIES IN THE ORGANIC MONOTECTIC ALLOYS
Authors: BÖYÜK U. , YÜCEER K. , KEŞLIOĞLU K. , ULGEN A. , MARAŞLI N.
Published: April 2009

The commercial purity dibromobenzene (DBB) and succinonitrile (SCN) were purified using a columnar distillation system. Thin walled rectangular specimen cells (60–80 μm thick) were fabricated and filled with the purified materials under the vacuum. The specimen cell was placed in a horizontal temperature gradient stage. A thin liquid layer was melted and the specimen was annealed in a constant temperature gradient for an enough time to observe the equilibrated grain boundary groove shapes. The thermal conductivities of solid and liquid phases for the purified DBB and DBB–5.7 mol% SCN alloy were determined with the radial heat flow and the Bridgman-type growth apparatuses. From the observed grain boundary groove shapes, the Gibbs–Thomson coefficients, solid–liquid interfacial energies, and the grain boundary energies for solid DBB in equilibrium with its melts and solid DBB in equilibrium with DBB–SCN monotectic liquid have been determined. The temperature coefficients of the purified DBB and DBB–5.7 mol% SCN alloy were also determined from thermal conductivity curve vs temperature.
THE SURFACE AND INTERFACE BEHAVIOR OF EMITTER REGION OF SOLAR CELLS IN PRODUCT LINE
Authors: LI F. , MA Z. Q. , HE B. , MENG X. J. , ZHOU C. Y. , ZHANG N. S.
Published: April 2009

Based on the Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), the specific surface and interface characteristics of emitter region of commercial mono-crystal Si solar cells were examined. Four chemical compositions C , O , Si , and P were detected, and the atomic concentrations (%) of C and O at the surface were much higher than their solid solubility in mono-crystal Si . The high concentration of C and O at the surface was attributed to adhered remains. The single element Si , stable oxide SiO 2, as well as intermediate oxidation states such as Si 1+ and Si 3+ corresponding to Si 2 O and Si 2 O 3, respectively, have been analyzed. The atomic concentrations (%) of these compositions and their respective chemical states at the surface and interface are likely correlative to the various defects such as electronic-like ramification of hanging bonds, vacancy cluster, or dislocations. Furthermore, the normalized quantum efficiency (QE) of the solar cells made from the wafers was measured to be lower than 74% at short wavelength (< 400 nm), and the influence of surface and interface states on the performance of solar cells was discussed.
THERMO-INDUCED SHIFT OF PLASMON ENERGY IN ELECTRON LOSS SPECTRA FOR THE ORDERING Pt80Co20(111) ALLOY SURFACE
Authors: TINKOV V. A. , VASYLYEV M. A.
Published: April 2009

Electron energy loss spectroscopy has been used for the investigation of the surface and bulk plasmon excitations depending on the heating in the ultra-thin layers of ordering Pt 80 Co 20(111) alloy from the primary electron beam energies E0 ranging from 200 to 650 eV. Thermo-induced shift of plasmon energy and damping of intensity line of the surface plasmon relative to the bulk plasmon were observed. With an increase in alloy heating, the energy of surface and bulk plasmons is shifted with lowering energy in the whole range E0 and the higher the temperature the higher the shifts of plasmon energy. The physical processes that can influence on the energy shift of plasmon oscillations in the energy loss spectra at heating are considered. The relationship between the damping of oscillating concentration depth profile and the surface plasmon damping at heating was established.
SURFACE METALIZATION ON THE PHOTO-EMISSION, PHOTO-ABSORPTION AND CORE-LEVEL SHIFT OF NANOSOLID SILICON
Authors: PAN LIKUN , LI HAIBO , SUN ZHUO , SUN CHANGQING
Published: April 2009

Cu , Al , and Ti films of ~ 10 nm thickness were deposited on porous silicon (PS) at room temperature using Filtered Cathodic Vacuum Arc system and annealed at 800°C for 10 min in vacuum. The PS layers were obtained by anodization of Si wafer. X-ray photoelectron spectroscopy, photoluminescence (PL), photo-absorption (PA), and X-ray diffraction studies revealed that before annealing just Cu -deposited sample exhibited PL blueshift, PA redshift, and Si -2p level shift due to the Cu diffusion at the surface of PS. While after annealing, Cu - and Ti -deposited samples exhibited obvious PA redshift and Si -2p level shift, which arise from the crystal field variation due to the formation of Cu / Ti silicides at the surface as well as the conduction electronic transportation.
PHONON SCATTERING VIA AN ATOMIC WELL IN FREE STANDING THIN SOLID FILMS
Authors: KHATER A. , BELHADI M.
Published: April 2009

A theoretical model is presented for the study of the scattering of phonons at an extended inhomogeneous boundary separating thin solid monatomic films. The model system consists of two solid films with otherwise stress-free surfaces on either side of an atomic well boundary. The coherent reflection and transmission scattering cross sections for phonons incident from the interior of the thin films on the inhomogeneous atomic well boundary are calculated in accordance with the Landauer–Büttiker coherent scattering description, using the matching method with nearest and next-nearest neighbor elastic force constants. This is done specifically for two different cases of elastic interactions on the boundary to investigate the consequences of their softening and hardening for the coherently scattered spectra. The numerical results yield an understanding for the effects on coherent phonon conductance due to phonon incidence and to the elastic nature of the boundary. The coherent reflection and transmission scattering cross sections show characteristic spectral features that are invariant with the change of the boundary force constants, depending solely on the cutoff frequencies for the propagating phonons and on incidence angle. They also show the Fano resonances that result from the interactions of propagating phonons with the localized vibrational Rayleigh-like modes on the boundary, depending on the boundary elastic force constants. The evolution of the system average conductance per phonon mode with incidence illustrates an interesting effect. An experimental observable this average conductance remains constant at half a phonon in intensity over significant frequency intervals. The effect is remarkable inasmuch as it permits in principle the possibility of a constant intensity phonon source.
APPLYING SURFACE ACOUSTIC WAVES TECHNIQUE FOR FILM ADHESIVENESS DETERMINATION
Authors: YOU X. Y. , XIAO XIA
Published: April 2009

Layered film structures are widely applied. The adhesiveness of thin layer, which controls the product quality, is a key factor to be known. The possibility of applying the surface acoustic waves (SAWs) technique to determine the adhesiveness quality of film and substrate is explored by a theoretical approach, where the interface adhesiveness is modeled by the spring model. Numerical results show that the proposed SAWs technique has a high resolution on determining the interface adhesiveness. Meanwhile, SAWs can also be applied to detect the parameters of film such as the elastic modulus, thickness, density, and Poisson's ratio nondestructively.
EFFECT OF SPECIMEN SIZE ON YOUNG'S MODULUS OF ELECTRODEPOSITED Ni
Authors: WANG HONG , LIU RUI , MAO SHENG-PING , TANG JUN , ZHANG CONG-CHUN , DING GUI-FU
Published: April 2009

The Young's moduli of electrodeposited Ni with different dimensions were measured carefully in this paper. The dimensions of tensile specimens were 200, 35, or 5 μm thick and 2400, 200 or 50 μm wide. These specimens were measured with three different approaches. The measured Young's moduli of Ni decrease from 122.1 ± 4.3 to 92 ± 5.2 GPa when the thickness changes from 200 to 5 μm and width changes from 2400 to 50 μm.
REVIEW OF TIDE GAUGE RECORDS IN THE INDIAN OCEAN
Authors: MATSUMOTO HIROYUKI , TANIOKA YUICHIRO , NISHIMURA YUICHI , TSUJI YOSHINOBU , NAMEGAYA YUICHI , NAKASU TADASHI , IWASAKI SIN-ITI
Published: April 2009

According to the NOAA earthquake database, at least 31 events have been found in the Indian Ocean in terms of tsunami event since 1900, most of which occurred along the Sunda Trench. In this study, we review the history of tide level measurements and their datasets archives in Thailand, Indonesia, India, and Australia. We collected tide gauge paper charts recording historical tsunamis including the 2004 Indian Ocean tsunami in those countries. As a result, systematic collection of historical tsunami records by tide gauges in the Indian Ocean has been difficult, because few tsunamigenic earthquakes occurred in the Indian Ocean during the instrumentally observed period.
Experiences with recombinant computing
Authors: Edwards W. Keith , Newman Mark W. , Sedivy Jana Z. , Smith Trevor F.
Published: April 2009

This article describes an infrastructure that supports the creation of interoperable systems while requiring only limited prior agreements about the specific forms of communication between these systems. Conceptually, our approach uses a set of “meta-interfaces”—agreements on how to exchange new behaviors necessary to
achieve compatibility at runtime
, rather than requiring that communication specifics be
built in at development time
—to allow devices on the network to interact with one another. While this approach to interoperability can remove many of the system-imposed constraints that prevent fluid, ad hoc use of devices now, it imposes its own limitations on the user experience of systems that use it. Most importantly, since devices may be expected to work with peers about which they have no detailed semantic knowledge, it is impossible to achieve the sort of tight semantic integration that can be obtained using other approaches today, despite the fact that these other approaches limit interoperability. Instead, under our model, users must be tasked with performing the sense-making and semantic arbitration necessary to determine how any set of devices will be used together. This article describes the motivation and details of our infrastructure, its implications on the user experience, and our experience in creating, deploying, and using applications built with it over a period of several years.
The calendar is crucial
Authors: Neustaedter Carman , Brush A. J. Bernheim , Greenberg Saul
Published: April 2009

Everyday family life involves a myriad of mundane activities that need to be planned and coordinated. We describe findings from studies of 44 different families' calendaring routines to understand how to best design technology to support them. We outline how a
typology of calendars
containing family activities is used by three different types of families—
monocentric
,
pericentric
, and
polycentric
—which vary in the level of family involvement in the calendaring process. We describe these family types, the content of family calendars, the ways in which they are extended through annotations and augmentations, and the implications from these findings for design.
TuG synopses for approximate query answering
Authors: Spiegel Joshua , Polyzotis Neoklis
Published: April 2009

This article introduces the Tuple Graph (TuG) synopses, a new class of data summaries that enable accurate approximate answers for complex relational queries. The proposed summarization framework adopts a “semi-structured” view of the relational database, modeling a relational data set as a graph of tuples and join queries as graph traversals, respectively. The key idea is to approximate the structure of the induced data graph in a concise synopsis, and to approximate the answer to a query by performing the corresponding traversal over the summarized graph. We detail the (TuG) synopsis model that is based on this novel approach, and we describe an efficient and scalable construction algorithm for building accurate (TuG) within a specific storage budget. We validate the performance of (TuG) with an extensive experimental study on real-life and synthetic datasets. Our results verify the effectiveness of (TuG) in generating accurate approximate answers for complex join queries, and demonstrate their benefits over existing summarization techniques.
Semantics and implementation of continuous sliding window queries over data streams
Authors: Krämer Jürgen , Seeger Bernhard
Published: April 2009

In recent years the processing of continuous queries over potentially infinite data streams has attracted a lot of research attention. We observed that the majority of work addresses individual stream operations and system-related issues rather than the development of a general-purpose basis for stream processing systems. Furthermore, example continuous queries are often formulated in some declarative query language without specifying the underlying semantics precisely enough. To overcome these deficiencies, this article presents a consistent and powerful operator algebra for data streams which ensures that continuous queries have well-defined, deterministic results. In analogy to traditional database systems, we distinguish between a logical and a physical operator algebra. While the logical algebra specifies the semantics of the individual operators in a descriptive but concrete way over temporal multisets, the physical algebra provides efficient implementations in the form of stream-to-stream operators. By adapting and enhancing research from temporal databases to meet the challenging requirements in streaming applications, we are able to carry over the conventional transformation rules from relational databases to stream processing. For this reason, our approach not only makes it possible to express continuous queries with a sound semantics, but also provides a solid foundation for query optimization, one of the major research topics in the stream community. Since this article seamlessly explains the steps from query formulation to query execution, it outlines the innovative features and operational functionality implemented in our state-of-the-art stream processing infrastructure.
Robust approximate aggregation in sensor data management systems
Authors: Considine Jeffrey , Hadjieleftheriou Marios , Li Feifei , Byers John , Kollios George
Published: April 2009

In the emerging area of sensor-based systems, a significant challenge is to develop scalable, fault-tolerant methods to extract useful information from the data the sensors collect. An approach to this data management problem is the use of sensor database systems, which allow users to perform aggregation queries such as MIN, COUNT, and AVG on the readings of a sensor network. In addition, more advanced queries such as frequency counting and quantile estimation can be supported. Due to energy limitations in sensor-based networks, centralized data collection is generally impractical, so most systems use in-network aggregation to reduce network traffic. However, even these aggregation strategies remain bandwidth-intensive when combined with the fault-tolerant, multipath routing methods often used in these environments. To avoid this expense, we investigate the use of approximate in-network aggregation using small sketches. We present duplicate-insensitive sketching techniques that can be implemented efficiently on small sensor devices with limited hardware support and we analyze both their performance and accuracy. Finally, we present an experimental evaluation that validates the effectiveness of our methods.
Analyzing communities and their evolutions in dynamic social networks
Authors: Lin Yu-Ru , Chi Yun , Zhu Shenghuo , Sundaram Hari , Tseng Belle L.
Published: April 2009

We discover communities from social network data and analyze the community evolution. These communities are inherent characteristics of human interaction in online social networks, as well as paper citation networks. Also, communities may evolve over time, due to changes to individuals' roles and social status in the network as well as changes to individuals' research interests. We present an innovative algorithm that deviates from the traditional two-step approach to analyze community evolutions. In the traditional approach, communities are first detected for each time slice, and then compared to determine correspondences. We argue that this approach is inappropriate in applications with noisy data. In this paper, we propose
FacetNet
for analyzing communities and their evolutions through a robust
unified
process. This novel framework will discover communities and capture their evolution with temporal smoothness given by historic community structures. Our approach relies on formulating the problem in terms of maximum a posteriori (MAP) estimation, where the community structure is estimated both by the observed networked data and by the prior distribution given by historic community structures. Then we develop an iterative algorithm, with proven low time complexity, which is guaranteed to converge to an optimal solution. We perform extensive experimental studies, on both synthetic datasets and real datasets, to demonstrate that our method discovers meaningful communities and provides additional insights not directly obtainable from traditional methods.
Blocking links to minimize contamination spread in a social network
Authors: Kimura Masahiro , Saito Kazumi , Motoda Hiroshi
Published: April 2009

We address the problem of minimizing the propagation of undesirable things, such as computer viruses or malicious rumors, by blocking a limited number of links in a network, which is converse to the influence maximization problem in which the most influential nodes for information diffusion is searched in a social network. This minimization problem is more fundamental than the problem of preventing the spread of contamination by removing nodes in a network. We introduce two definitions for the contamination degree of a network, accordingly define two contamination minimization problems, and propose methods for efficiently finding good approximate solutions to these problems on the basis of a naturally greedy strategy. Using large social networks, we experimentally demonstrate that the proposed methods outperform conventional link-removal methods. We also show that unlike the case of blocking a limited number of nodes, the strategy of removing nodes with high out-degrees is not necessarily effective for these problems.
Modeling information-seeker satisfaction in community question answering
Authors: Agichtein Eugene , Liu Yandong , Bian Jiang
Published: April 2009

Question Answering Communities such as Naver, Baidu Knows, and Yahoo! Answers have emerged as popular, and often effective, means of information seeking on the web. By posting questions for other participants to answer, information seekers can obtain specific answers to their questions. Users of CQA portals have already contributed millions of questions, and received hundreds of millions of answers from other participants. However, CQA is not always effective: in some cases, a user may obtain a perfect answer within minutes, and in others it may require hours—and sometimes days—until a satisfactory answer is contributed. We investigate the problem of predicting information seeker satisfaction in collaborative question answering communities, where we attempt to predict whether a question author will be satisfied with the answers submitted by the community participants. We present a general prediction model, and develop a variety of content, structure, and community-focused features for this task. Our experimental results, obtained from a large-scale evaluation over thousands of real questions and user ratings, demonstrate the feasibility of modeling and predicting asker satisfaction. We complement our results with a thorough investigation of the interactions and information seeking patterns in question answering communities that correlate with information seeker satisfaction. We also explore
personalized
models of asker satisfaction, and show that when sufficient interaction history exists, personalization can significantly improve prediction accuracy over a “one-size-fits-all” model. Our models and predictions could be useful for a variety of applications, such as user intent inference, answer ranking, interface design, and query suggestion and routing.
How Do I Model State? Let Me Count the Ways
Authors: Foster Ian , Parastatidis Savas , Watson Paul , McKeown Mark
Published: April 2009

There is nothing like a disagreement concerning an arcane technical matter to bring out the best (and worst) in software architects and developers. As every reader knows from experience, it can be hard to get to the bottom of what exactly is being debated. One reason for this lack of clarity is often that different people care about different aspects of the problem. In the absence of agreement concerning the problem, it can be difficult to reach an agreement about the solutions.
SHARPE at the age of twenty two
Authors: Trivedi Kisho S. , Sahner Robin
Published: April 2009

This paper discusses the modeling tool called SHARPE (Symbolic Hierarchical Automated Reliability and Performance Evaluator), a general hierarchical modeling tool that analyzes stochastic models of reliability, availability, performance, and performability. It allows the user to choose the number of levels of models, the type of model at each level, and which results from each model level are to act as which parameters in which higher-level models. SHARPE includes algorithms for analysis of fault trees, reliability block diagrams, acyclic series-parallel graphs, acyclic and cyclic Markov and semi-Markov models, generalized stochastic Petri nets, and closed single- and multi-chain product-form queueing networks. For many of these, the user can choose among alternative algorithms, and can decide whether to get a result in the form of a distribution function (symbolic in the time variable) or as a mean or probability. SHARPE has been useful to students, practicing engineers, and researchers. In this paper we discuss the history of SHARPE, give some examples of its use, and talk about some lessons learned.
CEOs
Authors: Bertrand Marianne
Published: April 2009

This article starts with an overview of the characteristics of chief executive officers (CEOs). I discuss the rising importance of general skills over firm-specific skills and the growing share of externally recruited CEOs. I also discuss possible reasons for the underrepresentation of women and the overrepresentation of family members in the corporate suite. I then review the three main explanations that have been put forward to explain the surge in CEO compensation over the past 30 years: principal-agent view, rent extraction view, and market-based view. I assess the strengths and weaknesses of each of these explanations in light of the existing empirical research. Finally, I review work on how entrenched CEOs or cognitively biased CEOs may cause corporate practices to deviate from the maximization of firm value.
Cystic fibrosis transmembrane conductance regulator and caveolin-1 regulate epithelial cell internalization of Pseudomonas aeruginosa
Authors: Bajmoczi Milan , Gadjeva Mihaela , Alper Seth L. , Pier Gerald B. , Golan David E.
Published: April 2009

Patients with cystic fibrosis (CF) exhibit defective innate immunity and are susceptible to chronic lung infection with Pseudomonas aeruginosa. To investigate the molecular bases for the hypersusceptibility of CF patients to P. aeruginosa, we used the IB3-1 cell line with two defective CF transmembrane conductance regulator (CFTR) genes (ΔF508/W1282X) to generate isogenic stable, clonal lung epithelial cells expressing wild-type (WT)-CFTR with an NH2-terminal green fluorescent protein (GFP) tag. GFP-CFTR exhibited posttranslational modification, subcellular localization, and anion transport function typical of WT-CFTR. P. aeruginosa internalization, a component of effective innate immunity, required functional CFTR and caveolin-1, as shown by: 1) direct correlation between GFP-CFTR expression levels and P. aeruginosa internalization; 2) enhanced P. aeruginosa internalization by aminoglycoside-induced read through of the CFTR W1282X allele in IB3-1 cells; 3) decreased P. aeruginosa internalization following siRNA knockdown of GFP-CFTR or caveolin-1; and 4) spatial association of P. aeruginosa with GFP-CFTR and caveolin-1 at the cell surface. P. aeruginosa internalization also required free lateral diffusion of GFP-CFTR, allowing for bacterial coclustering with GFP-CFTR and caveolin-1 at the plasma membrane. Thus efficient initiation of innate immunity to P. aeruginosa requires formation of an epithelial “internalization platform” involving both caveolin-1 and functional, laterally mobile CFTR.
Dorsomedial medullary 5-HT2 receptors mediate immediate onset of initial hyperventilation, airway dilation, and ventilatory decline during hypoxia in mice
Authors: Kanamaru Mitsuko , Homma Ikuo
Published: April 2009

The dorsomedial medulla oblongata (DMM) includes the solitary tract nucleus and the hypoglossal nucleus, to which 5-HT neurons project. Effects of 5-HT in the DMM on ventilatory augmentation and airway dilation are mediated via 5-HT2 receptors, which interact with the CO2drive. The interaction may elicit cycles between hyperventilation with airway dilation and hypoventilation with airway narrowing. In the present study, effects of 5-HT2 receptors in the DMM on hypoxic ventilatory and airway responses were investigated, while 5-HT release in the DMM was monitored. Adult male mice were anesthetized, and then a microdialysis probe was inserted into the DMM. The mice were placed in a double-chamber plethysmograph. After recovery from anesthesia, the mice were exposed to hypoxic gas (7% O2in N2) for 5 min with or without a 5-HT2 receptor antagonist (LY-53857) perfused in the DMM. 5-HT release in the DMM was increased by hypoxia regardless of the presence of LY-53857. Immediate onset and the peak of initial hypoxic hyperventilatory responses were delayed. Subsequent ventilatory decline and airway dilation during initial hypoxic hyperventilation were suppressed with LY-53857. These results suggest that 5-HT release increased by hypoxia acts on 5-HT2 receptors in the DMM, which contributes to the immediate onset of initial hypoxic hyperventilation, airway dilation, and subsequent ventilatory decline. Hypoxic ventilatory and airway responses mediated via 5-HT2 receptors in the DMM may play roles in immediate rescue and defensive adaptation for hypoxia and may be included in periodic breathing and the pathogenesis of obstructive sleep apnea.
Diffusive Synchronization of Hyperchaotic Lorenz Systems
Authors: Barboza Ruy
Published: April 2009

The synchronizing properties of two diffusively coupled hyperchaotic Lorenz 4D systems are investigated by calculating the transverse Lyapunov exponents and by observing the phase space trajectories near the synchronization hyperplane. The effect of parameter mismatch is also observed. A simple electrical circuit described by the Lorenz 4D equations is proposed. Some results from laboratory experiments with two coupled circuits are presented.
An Iterative Technique for the Synthesis of Active Antenna Oscillator Arrays
Authors: Kaifas Theodoros N. , Sahalos John N.
Published: April 2009

A design procedure for the synthesis of a coupled active antenna oscillator array is presented. Such an array is synthesized by deriving two sets of parameters: the radiators' positions and the oscillators' outputs. The outputs are used to excite the radiators. Minimization of the mean square error between the desired pattern and the resulting one is made. Synthesis starts from an initial array, which is perturbed iteratively by varying simultaneously the element excitations and positions. In the iteration, the first variation of the cost function is set equal to zero. The final array results from the last iteration, where the stopping criteria are met. The procedure designs simultaneously both the antenna and the attached coupled oscillator array providing viable solutions. The second by properly configuring the tuning parameters through the use of closed-form formulas. The resulting arrays are shown to comply with the desired pattern and the nonlinear dynamics thus proving the validity of our method.
Hemoperitoneum in a Cirrhotic Patient Due to Rupture of Retroperitoneal Varix
Authors: Sincos Igor Rafael , Mulatti Grace , Mulatti Sheila , Sincos Ilana Cristina , Belczak Sergio Q. , Zamboni Valdir
Published: April 2009

The rupture of retroperitoneal varices is a rare and catastrophic complication of portal hypertension. We describe a case of this nature, the first in Brazilian medical literature, and also reviewing all previous 34 cases. We systematically analyzed all therapeutic approach and propose a management algorithm for diagnosis and treatment of this lethal condition. The majority of the patients presented with abdominal pain, distention and hypotension, and developed hemorrhagic shock. Rupture of retroperitoneal varices can be properly managed if an early diagnosis is made and surgery is performed promptly, which is the only effective treatment. Arteriography should be used when the suspicion is of rupture of hepatocellular carcinoma.
Flow Around a Slender Circular Cylinder: A Case Study on Distributed Hopf Bifurcation
Authors: Aranha J. A. P. , Burr K. P. , Barbeiro I. C. , Korkischko I. , Meneghini J. R.
Published: April 2009

This paper presents a short overview of the flow around a slender circular cylinder, the purpose being to place it within the frame of the distributed Hopf bifurcation problems described by the Ginzburg‐Landau equation (GLE). In particular, the chaotic behavior superposed to a well tuned harmonic oscillation observed in the range Re > 270, with Re being the Reynolds number, is related to the defect‐chaos regime of the GLE. Apparently new results, related to a Kolmogorov like length scale and the rms of the response amplitude, are derived in this defect‐chaos regime and further related to the experimental rms of the lift coefficient measured in the range Re > 270.
Statistical Analysis of Microarray Data with Replicated Spots: A Case Study withSynechococcusWH8102
Authors: Thomas E. V. , Phillippy K. H. , Brahamsha B. , Haaland D. M. , Timlin J. A. , Elbourne L. D. H. , Palenik B. , Paulsen I. T.
Published: April 2009

Until recently microarray experiments often involved relatively few arrays with only a single representation of each gene on each array. A complete genome microarray with multiple spots per gene (spread out spatially across the array) was developed in order to compare the gene expression of a marine cyanobacterium and a knockout mutant strain in a defined artificial seawater medium. Statistical methods were developed for analysis in the special situation of this case study where there is gene replication within an array and where relatively few arrays are used, which can be the case with current array technology. Due in part to the replication within an array, it was possible to detect very small changes in the levels of expression between the wild type and mutant strains. One interesting biological outcome of this experiment is the indication of the extent to which the phosphorus regulatory system of this cyanobacterium affects the expression of multiple genes beyond those strictly involved in phosphorus acquisition.
Idiopathic Thrombocytopenic Purpura Presenting as Iron-Responsive Thrombocytopenia
Authors: Michaeli Joseph , Admon Dan , Lugassy Gilles , Matzner Yaacov
Published: April 2009

We describe a patient with iron-deficiency anemia, thrombocytopenia and paucity of marrow megakaryocytes, in whom the anemia and the thrombocytopenia responded to the administration of iron. Thrombocytopenia recurred, despite maintenance of normal hemoglobin and iron levels and adequate marrow megakaryocytes. Corticoste-roids and splenectomy were required for the control of the thrombocytopenia. In this patient, the initial manifestations of idiopathic thrombocytopenic purpura were modified by the presence of severe iron deficiency. This case strengthens the contention that iron is essential for megakaryopoiesis and thrombopoiesis.
Unprotected Left Main Stenting in the Real World
Authors: Vaquerizo Beatriz , Lefèvre Thierry , Darremont Olivier , Silvestri Marc , Louvard Yves , Leymarie Jean Louis , Garot Philippe , Routledge Helen , de Marco Federico , Unterseeh Thierry , Zwahlen Marcel , Morice Marie-Claude
Published: April 2009

Background—

Cardiac surgery is the reference treatment for patients with left main (LM) disease, although percutaneous coronary intervention with drug-eluting stents is emerging as a possible alternative. The objective of this registry was to evaluate the 2-year outcome of elective percutaneous coronary intervention for unprotected LM disease with paclitaxel-eluting stents.

Methods and Results—

A total of 291 patients were prospectively included from 4 centers. Acute myocardial infarction and cardiogenic shock were the only exclusion criteria. Patients were 69±11 years old, 29% were diabetic, and 25% had 3-vessel disease. For distal LM lesions (78%), the provisional side-branch T-stenting approach was used in 92% of cases and final kissing balloon inflation in 97%. Angiographic success was obtained in 99.7% of cases. At 2-year follow-up, the total cardiac death rate was 5.4% (1 EuroSCORE point was associated with a 15% [95% confidence interval 2.9% to 28.2%,
P
=0.013] higher risk of cardiac death), target-lesion revascularization was 8.7%, and incidence of Q-wave or non–Q-wave myocardial infarction was 0.9% and 3.1%, respectively. The combined end point occurred in 15.8% of cases and stroke in 0.7%. The incidence of definite and probable LM stent thrombosis was 0.7%, whereas the incidence of any stent thrombosis was 3.8%, with a higher risk in patients with side-branch stenting in the presence of LM bifurcation lesions (hazard ratio 9.6, 95% confidence interval 1.2 to 77.7,
P
=0.035).

Conclusions—

Unprotected LM stenting with paclitaxel-eluting stents, with a strategy of provisional side-branch T-stenting for distal lesions, provides excellent acute angiographic results and good mid-term clinical outcomes, with a 15.8% rate of major adverse cardiac events at 2-year follow-up.
Mean-Field Approximations for Coupled Populations of Generalized Linear Model Spiking Neurons with Markov Refractoriness
Authors: Toyoizumi Taro , Rad Kamiar Rahnama , Paninski Liam
Published: April 2009

There has recently been a great deal of interest in inferring network connectivity from the spike trains in populations of neurons. One class of useful models that can be fit easily to spiking data is based on generalized linear point process models from statistics. Once the parameters for these models are fit, the analyst is left with a nonlinear spiking network model with delays, which in general may be very difficult to understand analytically. Here we develop mean-field methods for approximating the stimulus-driven firing rates (in both the time-varying and steady-state cases), auto- and cross-correlations, and stimulus-dependent filtering properties of these networks. These approximations are valid when the contributions of individual network coupling terms are small and, hence, the total input to a neuron is approximately gaussian. These approximations lead to deterministic ordinary differential equations that are much easier to solve and analyze than direct Monte Carlo simulation of the network activity. These approximations also provide an analytical way to evaluate the linear input-output filter of neurons and how the filters are modulated by network interactions and some stimulus feature. Finally, in the case of strong refractory effects, the mean-field approximations in the generalized linear model become inaccurate; therefore, we introduce a model that captures strong refractoriness, retains all of the easy fitting properties of the standard generalized linear model, and leads to much more accurate approximations of mean firing rates and cross-correlations that retain fine temporal behaviors.
Competitive STDP-Based Spike Pattern Learning
Authors: Masquelier Timothée , Guyonneau Rudy , Thorpe Simon J.
Published: April 2009

Recently it has been shown that a repeating arbitrary spatiotemporal spike pattern hidden in equally dense distracter spike trains can be robustly detected and learned by a single neuron equipped with spike-timing-dependent plasticity (STDP) (Masquelier, Guyonneau, & Thorpe, 2008). To be precise, the neuron becomes selective to successive coincidences of the pattern.

Here we extend this scheme to a more realistic scenario with multiple repeating patterns and multiple STDP neurons “listening” to the incoming spike trains. These “listening” neurons are in competition: as soon as one fires, it strongly inhibits the others through lateral connections (one-winner-take-all mechanism). This tends to prevent the neurons from learning the same (parts of the) repeating patterns, as shown in simulations. Instead, the population self-organizes, trying to cover the different patterns or coding one pattern by the successive firings of several neurons, and a powerful distributed coding scheme emerges.

Taken together, these results illustrate how the brain could easily encode and decode information in the spike times, a theory referred to as temporal coding, and how STDP could play a key role by detecting repeating patterns and generating selective response to them.
A Pilot Study of Video Compression Techniques for Stereoscopic Telepresence Applications
Authors: Fok Stanley , Wang David W. L , Ni Liya , Freeman George
Published: April 2009

This paper focuses on evaluating and quantifying the effects of a novel foveated stereo video compression algorithm for visual telepresence applications. In a typical telepresence application, a user at the local site views real-time stereo video captured and transmitted from a telerobotic camera platform located at a remote site. The telerobotic camera platform tracks the user's head motion, producing the sensation of being present at the remote site. Three valuable factors were examined: foveation, disparity compression, and global motion compensation. The algorithm was analyzed by introducing the above-mentioned components separately. It was found that each component increased the compression rate significantly.