bluuebunny/crossref_metadata_2025 huggingface dataset:
A new hexactinellid sponge from the Cretaceous of Devon Island, Canadian High Arctic
Authors: Rigby J Keith , Chin Karen , Bloch John D , Tweet Justin S
Published: October 2007

Over 20 specimens of the new genus and species Nunavutospongia irregulara, an irregular stump-like to columnar, or fan- to blade-shaped, hexactinosid hexactinellid sponge, have been recovered from exposures of the Upper Cretaceous upper Kanguk Formation on Devon Island, Nunavut Territory, in the Canadian High Arctic. The species and genus are characterized by dermal surfaces with prominent radial, irregularly vertical, rib-like flanges that have a single linear series of separated oscula perforating their rounded crests. The thin, but persistent dermal layer of fused hexactine-based spicules has rays thicker than those of the similarly fused endosomal, quadrangularly arranged, hexactines of the principal skeleton. Ostia of coarse exhalant canals, and finer inhalant canals, are extensively and uniformly developed, but irregularly placed, in the dermal layer. A thin, less prominent, gastral layer of thickened spicules lines the short, internally tapered spongocoel openings. The skeleton exposed in the commonly upward-arcuate base of each sponge has a radiate structure that does not have significant ostia. The new genus is tentatively included in the Family Cribrospongiidae Roemer, 1864, within the Order Hexactinosa Schrammen, 1903. The specimens were found in unconsolidated fine-grained glauconitic sediments along with other fossils such as fish teeth, bird bones, lingulids, coprolites, and wood. The sedimentology, stratigraphic context, and co-occurrence with fossil wood suggest that these sponges inhabited the neritic zone. As such, they would have been subject to polar light regimes, because paleogeographic reconstructions indicate that Devon Island was above the Arctic Circle during the Late Cretaceous. The distribution of the specimens suggests that they were solitary sponges that used their arcuate bases to colonize sandy substrates or biotic debris.
A new ceratopsid dinosaur (Ornithischia) from the uppermost Horseshoe Canyon Formation (upper Maastrichtian), Alberta, Canada
Authors: Wu Xiao-chun , Brinkman Donald B , Eberth David A , Braman Dennis R
Published: October 2007

A skeleton of a new ceratopsid dinosaur, Eotriceratops xerinsularis gen. et sp. nov., is described in this paper. It is the first associated vertebrate skeleton found within the upper 20 m of the Horseshoe Canyon Formation. Eotriceratops xerinsularis is a large chasmosaurine that differs from other chasmosaurines in a unique set of features in the premaxilla, nasal horn core, squamosal frill, and epijugal. The most striking of those features includes an extremely tall, non-recessed narial process of the premaxilla; the presence of greatly elongate, spindle-shaped epoccipitals on the squamosal frill; a deep, well-demarcated fossa on the anteroventral surface of the squamosal frill; a sharply conical epijugal with a pronounced proximoposterior process and separate fossa-like facets for the jugal and quadratojugal; and the presence of an obliquely extending vascular trace meeting a transverse vascular trace ventrally on the anterior surface of the nasal horn core. Our phylogenetic analysis suggests that E. xerinsularis is nested within a clade including Triceratops, Diceratops, and Torosaurus, which are all from late Maastrichtian deposits. The upper 20 m of the Horseshoe Canyon Formation comprises a coal-rich interval (Carbon–Thompson coal zone, unit 5), which previously has been assigned to upper Maastrichtian magnetochrons 31n and 30r, and the Mancicorpus gibbus miospore subzone. The ceratopsid specimen was collected from between the Carbon and Thompson coal seams, and thus, is inferred to (1) occur near the top of magnetochron 31n and (2) have an age of 67.6–68.0 Ma. Large chasmosaurine ceratopsids, such as Triceratops and Torosaurus, have not previously been described from the Horseshoe Canyon Formation or from magnetochron 31n or the M. gibbus miospore subzone. Thus, Eotriceratops is distinctly older than any other ceratopsid in the Triceratops group, and the discovery of E. xerinsularis helps fill a biostratigraphic gap between early and late Maastrichtian chasmosaurines.
Cretaceous reduced granitoids in the Goodpaster Mining District, east central Alaska
Authors: Dilworth Katherine M , Mortensen James K , Ebert Shane , Tosdal Richard M , Smith Moira T , Roberts Paul
Published: October 2007

The >5 Moz (1 oz (troy) = 31.103 g) gold veins of the Liese Zone and nearby prospects in the Goodpaster Mining District of east central Alaska are spatially and temporally associated with late-Early to Late Cretaceous reduced granitoids that are divided into a granite suite, tonalite suite, and diorite suite in decreasing age. Synkinematic to postkinematic biotite ± hornblende granite, granodiorite, pegmatite, and two-mica granite with accessory garnet compose the granite suite (109–107 Ma). The tonalite suite (107–103 Ma) forms small to large bodies of postkinematic hornblende–biotite granodiorite to tonalite with rare granite. Intruding the granite and parts of the tonalite suites are aplite and pegmatite that grade through sugary pegmatoidal or aplitic quartz veins and finally into quartz veins along strike. The diorite suite (95.4–93.7 Ma) consists of small stocks of diorite to tonalite that intrude the older suites and are inferred to intrude the shallowly dipping auriferous quartz veins. Limited data indicate granitoid emplacement at 5–9 km depths, consistent with formation of the auriferous quartz veins based upon published fluid inclusion data. The weakly peraluminous granite and tonalite suites are distinguished by variable amounts of monazite and zircon whereas the diorite suite is metaluminous, contains <5% magnetite, and lacks monazite. All suites are subalkalic, calc-alkaline and have low magnetic susceptibilities, high large-ion lithophile element/high field-strength element (LILE/HFSE), and depleted Nb and Ti. The granite suite has higher206Pb/204Pb values (19.4–19.6) than the diorite (19.1). Overall the granite and tonalite suites likely represent melts generated late during crustal thickening that intruded along shallowly dipping faults during exhumation, whereas the diorite suite represents postdeformation melts that underwent less interaction with the old silicic crust.
Brachiopods from Bird Fiord Formation (Devonian) of Arctic Canada
Authors: Li Rong-Yu , Jones Brian
Published: October 2007

The upper Lower to Middle Devonian Bird Fiord Formation (late Emsian to late Eifelian) is a carbonate–siliciclastic succession, up to 900 m thick, that contains a diverse brachiopod-dominated fauna. Twenty-two species belonging to 21 genera have been recognized from the collection of more than 45 000 specimens, among which the atrypids form 52% of the biota, spiriferids ~13%, orthids ~8%, productids ~3%, rhynchonellids ~2%, terebratulids ~1%, and the strophomenids, pentamerids, and athyridids each <1%. Spinatrypina, Schizophoria, Elythyna, Desqumatia (Independentrypa), Cupularostrum, and Atrypa that collectively form more than 80% of the brachiopod biota. The following species are described here: Schizophoria (Schizophoria) sulcata, Ivdelinia grinnellensis, Cupularostrum repetitor, Hypothyridina cf. bifurcata, Atrypa sp., Emanuella bisinuata, Elythyna sverdrupi, Perryspirifer scheii, Costacranaena marlenae. Despite its endemic character, the brachiopod fauna from the Bird Fiord Formation of Arctic Canada can be assigned to the Old World Realm. Its strong affinity to Europe and western Canada supports the notion that, during the Devonian, faunal exchanges between Europe and North America took place via Arctic Canada.
Micro X-ray diffraction (µXRD): a versatile technique for characterization of Earth and planetary materials
Authors: Flemming Roberta L
Published: October 2007

Recent developments in laboratory-based micro X-ray diffraction (µXRD) have extended X-ray examination of geomaterials to the microscopic level (50–500 µm), greatly expanding the applicability of XRD to mineralogy, petrology, materials, environmental, and planetary sciences. Laboratory-based µXRD has been accomplished using a Bruker D8 Discover diffractometer, having a sealed-tube Cu source, theta–theta geometry, Gobel mirror parallel optics with 50–500 µm collimation, and general area detector diffraction system (GADDS). A wide range of samples, including polished thin sections, electron probe microanalysis (EPMA) mounts, rock slabs, whole rocks, and powders have been examined with µXRD using a remote-controlled XYZ sample stage, with imaging by optical microscope monitor and charge-coupled device (CCD) camera. Individual grains in heterogeneous samples have been examined in situ, with little or no sample preparation. The two-dimensional GADDS preserves textural and crystallinity information (e.g., bioapatite) and easily discriminates between multiple phases of utility for synthetic or natural samples (e.g., mine tailings). In situ µXRD of minerals preserves spatial relationships, enabling study of orientational phenomena, such as strain-related mosaicity (giving “streaked” diffraction lines). Examples include strained quartz (La Malbaie quartzite, Quebec) and shocked clinopyroxenes (Shergottite NWA 3171). Mineral mapping has been demonstrated by reproducing exsolution textures of kamacite from taenite (Widmanstätten pattern) in the Toluca iron meteorite. Diffraction data obtained from single crystals (by the omega scan method) have enabled grain-by-grain correlation between unit cell (µXRD) and chemical composition (EPMA), as demonstrated by kimberlite indicator garnets. The examples shown herein demonstrate the breadth of information that can be obtained by µXRD of Earth and planetary materials.
Ecological correlates of fish reproductive activity in floodplain rivers: a life-history-based approach
Authors: Zeug Steven C , Winemiller Kirk O
Published: October 2007

Reproductive activity of seven species representing three divergent life history strategies was monitored monthly for 2 years in channel and floodplain habitats of the Brazos River, Texas, USA, to evaluate associations between reproductive activity and biotic and abiotic factors predicted by conceptual models to influence reproduction. An information-theoretic approach was used to select best approximating models for each species, and model-averaged estimates of regression coefficients were calculated. Model selection indicated that monthly flow based on the 30-year hydrograph and temperature was strongly supported as factors associated with reproductive activity of all three life history strategies. The timing of reproduction in relation to the long-term hydrograph was related to life history traits. Reproductive activity of species with large adult size and high fecundity was greatest in spring just prior to increasing flows, whereas species with small adult size and extended breeding seasons exhibited greater activity in late spring and summer when mean flow was greatest. Nest-building species with parental care were more abundant in off-channel habitats where floods were less common. Instream flow management would benefit from consideration of flow and habitat requirements needed to support the diverse life history strategies displayed by fishes in river–floodplain systems.
Consumption of two exotic zooplankton by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in three Laurentian Great Lakes
Authors: Storch Adam J , Schulz Kimberly L , Cáceres Carla E , Smyntek Peter M , Dettmers John M , Teece Mark A
Published: October 2007

Introductions of the zooplankton Bythotrephes longimanus and Cercopagis pengoi into the Great Lakes have drawn attention surrounding their suitability as prey for zooplanktivorous fishes. We used gut contents and stable carbon isotopes to quantify differential consumption and selection of the exotics by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in Lakes Erie, Michigan, and Ontario. The exotics were more often consumed by alewife (up to 70% of gut content biomass) than by smelt (up to 25% of gut content biomass). Measured stable carbon isotope ratios of fish and ratios predicted from mixing models confirmed that the snapshot descriptions of diet through gut contents were representative of longer-term diets. While B. longimanus generally was selected for (14 of 17 sampling dates), C. pengoi was not a preferred prey item. Cercopagis pengoi was sometimes a large component of alewife diet because of its high densities in the environment. The exotic zooplankton are more important for alewife than for smelt, and consumption of the cladocerans varies throughout the growing season and among lakes, generally related to patterns of exotic abundance. Effects associated with consumption of the exotics should be high in alewife-dominated systems invaded by B. longimanus or large numbers of C. pengoi.
Effects of colonizing predators on yellow perch (Perca flavescens) populations in lakes recovering from acidification and metal stress
Authors: Lippert Kelly A , Gunn John M , Morgan George E
Published: October 2007

We examined the effects of predator species on yellow perch (Perca flavescens) from lakes in the Sudbury mining region (Ontario, Canada), where fish communities are just beginning to recover from the effects of decades of acidification and metal stress. The predation regimes investigated included six lakes with no predators, four lakes recently invaded (≤3 years) by predators, and eight lakes with well-established (≥15 years) predator populations. Netting survey results indicated that yellow perch biomass was 69% lower in lakes with predators. In lakes recently invaded by predators, perch displayed earlier ontogenetic diet shifts from zooplankton to benthos and much poorer growth during their first growing season. Energy investment (lipid content per egg) in eggs by mature females was also less in the lakes recently invaded by predators. Growth potential in adult perch (age 1), estimated by nucleoside diphosphokinase, was highest in lakes with established predators. Body condition, controlling for size of perch, was also greatest in established predator lakes. Perch body shape in lakes with predators showed a shift from a typical streamlined, pelagic body form towards a deeper-bodied benthic body form, a change that may increase foraging efficiency for benthos or represent an antipredator strategy.
Spatial and temporal variation in shark communities of the lower Florida Keys and evidence for historical population declines
Authors: Heithaus Michael R , Burkholder Derek , Hueter Robert E , Heithaus Linda I , Pratt, Jr. Harold L , Carrier Jeffrey C
Published: October 2007

Sharks are top predators in many marine ecosystems. Despite recent concerns over declines in shark populations, studies of shark communities in coastal habitats are limited. We used drumlines and longlines to determine shark community composition and habitat affinities in the Florida Keys, USA. Community composition varied among habitats. Catch rates of smaller sharks were highest in protected shallow waters, while large sharks were more abundant in deep channels. Overall probabilities of catching large sharks on drumlines did not vary with water temperature, while catches of small sharks on longlines increased with increasing water temperature. Individual species differed in their responsiveness to variation in water temperatures and habitat. Bait type affected catch rates of some species, suggesting that fishing methods should be considered explicitly in studies describing shark communities or temporal trends in abundance. Catch rates of large-bodied sharks were higher in a remote and protected location compared with similar habitats near inhabited Keys. Also, historical accounts of a shark fishery in the study area during the 1920s suggest substantial declines in large shark abundance and shifts in community composition. By implication, ecosystem impacts of changes in the large shark community may be dramatic and likely occurred before adequate baselines were established.
Is there a role for vision in the behaviour of sea lampreys (Petromyzon marinus) during their upstream spawning migration?
Authors: Binder Thomas R , McDonald D Gordon
Published: October 2007

This study found no evidence to support a role for vision in the behaviour of sea lampreys (Petromyzon marinus) during their spawning migration. Blindness had no affect on the migratory propensity of lampreys, and control and blinded animals moved upstream at the same rate. The diel activity pattern of control and blinded lampreys was identical in both the laboratory and field. Activity was mostly nocturnal, but lampreys in the field did show some daytime activity. Diel activity broke down when lampreys were unable to locate suitable daytime refuge, but blindness did not affect the willingness or ability of lampreys to do so in either the laboratory or field. Laboratory studies indicate that light avoidance is mediated by dermal photoreceptors located in the tail, but the data suggests that refuge sites are sought out before sunrise using tactile and possibly hydraulic cues. Thus, light-induced searching only occurs when the sites chosen at night do not provide adequate concealment after sunrise.
Multiscale effects of flow regime and habitat and their interaction on fish assemblage structure in eastern Australia
Authors: Kennard Mark J , Olden Julian D , Arthington Angela H , Pusey Bradley J , Poff N LeRoy
Published: October 2007

We examine the multiscale influence of environmental and hydrological features of the riverine landscape on spatial and temporal variation in fish assemblages in eastern Australia. Multiresponse artificial neural network models provided accurate predictions of fish assemblages in the Mary River based on species presence–absence data (mean Bray–Curtis similarity between predicted and observed composition = 84%) but were less accurate when based on species relative abundance or biomass (mean similarity = 62% and 59%, respectively). Landscape- and local-scale habitat variables (e.g., catchment area and riparian canopy cover) and characteristics of the long-term flow regime (e.g., variability and predictability of flows) were more important predictors of fish assemblages than variables describing the short-term history of hydrological events. The relative importance of these variables was broadly similar for predicting species occurrence, relative abundance, or biomass. The transferability of the Mary River predictive models to the nearby Albert River was high for species presence–absence (i.e., closer match between predicted and observed data) compared with species abundances or biomass. This suggests that the same landscape-scale features are important determinants of distribution of individual species in both rivers but that interactions between landscape, hydrology, and local habitat features that collectively determine abundance and biomass may differ.
Differential expression of corticosteroid receptor genes in rainbow trout (Oncorhynchus mykiss) immune system in response to acute stress
Authors: Yada Takashi , Azuma Teruo , Hyodo Susumu , Hirano Tetsuya , Grau E Gordon , Schreck Carl B
Published: October 2007

Expression of distinct corticosteroid receptor genes, glucocorticoid receptors 1 and 2 (GR-1 and GR-2, respectively) and mineralcorticoid receptor (MR), was quantified by real-time polymerase chain reaction (PCR) in peripheral blood leucocytes (PBL), spleen, and gill of rainbow trout (Oncorhynchus mykiss) after an acute netting stress. Plasma cortisol levels were significantly increased 2 h after stress and returned to prestress levels within 24 h. Consistent with changes in plasma cortisol, GR-2 mRNA levels in PBL increased significantly at 2 h after stress, returning to initial levels by 8 h. In contrast, GR-1 and MR levels in PBL decreased significantly at 24 h after stress, and these reduced levels were maintained for 7 days. Splenic mRNA levels of GR-1 and GR-2 also decreased at 8 h and 24 h after stress, returning to control levels by 7 days, whereas no significant change was observed in MR. In gill, there was no obvious change in corticosteroid receptor mRNA levels after stress, except for a transient decrease at 8 h in MR. These results suggest a variety of roles for the three corticosteroid receptors during immunosuppression in response to acute stress in trout.
RF DEFLECTOR BASED SUB-PS BEAM DIAGNOSTICS: APPLICATION TO FEL AND ADVANCED ACCELERATORS
Authors: ALESINI DAVID
Published: October 2007

RF deflectors are very promising devices for longitudinal and transverse phase space characterization and beam manipulation in advanced accelerators. Measurement setups for longitudinal pulse shape as well as phase space and transverse beam slice emittance characterizations are described as well the main design criteria of traveling wave and standing wave RF deflectors used for beam diagnostics putting in evidence the advantages or disadvantages of the two devices in terms of performances, required power and power limitations.
DIAMOND SECONDARY EMITTER
Authors: BEN-ZVI I. , RAO T. , BURRILL A. , CHANG X. , GRIMES J. , RANK J. , SEGALOV Z. , SMEDLEY J.
Published: October 2007

We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.
PARAMETRIC OPTIMIZATION FOR AN X-RAY FREE ELECTRON LASER WITH A LASER WIGGLER
Authors: BONIFACIO R. , PIOVELLA N. , COLA M. M.
Published: October 2007

In this paper we optimize the experimental parameters to operate a Free Electron Laser with a laser wiggler in the Angstrom region. We show that the quantum regime of the Self Amplified Spontaneous Emission (Quantum SASE) may be reached with realistic parameters. The classical SASE regime is also discussed and compared with the quantum regime.
NON-LINEAR EVOLUTION OF SHORT PULSES IN FEL CASCADED UNDULATORS AND THE FEL HARMONIC CASCADE
Authors: GIANNESSI LUCA , MUSUMECI PIETRO
Published: October 2007

Free Electron Laser (FEL) devices based on sequence of amplifiers with an harmonic relation between the resonant frequencies of each section, have been proposed to extend to shorter wavelengths the FEL operating range. When this “cascade” of undulators is operated at intensities above saturation, a short optical pulse propagates in a solitary wave-like regime. The pulse is up-converted in frequency at the transitions between the cascade sections, according the resonance central frequency of each undulator. In this paper we briefly review the main dynamical aspects of the FEL cascade operating in this regime and we study the case where the undulators of the cascade are not resonant at the fundamental frequency but have one of the higher order harmonics at a common frequency. In these conditions high harmonic multiplication factors in the final stage may be obtained with a relatively low energy electron beam.
HIGH BRIGHTNESS LASER INDUCED MULTI-MEV ELECTRON/PROTON SOURCES
Authors: GIULIETTI D. , BRESCHI E. , GALIMBERTI M. , GIULIETTI A. , GIZZI L. A. , KOESTER P. , LABATE L. , TOMASSINI P. , MARTIN PH. , CECCOTTI T. , DE OLIVERA P. , MONOT P. , BORGHESI M. , ROMAGNANI L. , KAR S. , BERTOLUCCI S. , CALVETTI M. , SCHIAVI A. , WILLI O.
Published: October 2007

The chirped pulse amplification (CPA) technique has opened new perspectives in the radiation-matter interaction studies using ultra-short laser pulses at ultra-relativistic intensities. In particular the original idea, proposed by Tajima and Dawson, of accelerating electrons by the huge electric fields of plasma waves which develop in the wake of a laser pulse propagating in a plasma, become feasible. Some laboratories all over the world have produced by such a technique collimated electron busts of hundreds of MeV along acceleration lengths of a few hundreds of microns. In other experiments, using thin solid targets, intense bursts of energetic protons have been at the same time detected. The proton acceleration mechanism is essentially based on the Coulomb force appearing at the thin solid target surface as a consequence of the previous escape of the energetic electrons from the target. In the paper some experimental results will be presented as well as the opportunities the INFN PLASMONX project will offer in this research field at LNF.
EMITTANCE LIMITATION OF A CONDITIONED BEAM IN A STRONG FOCUSING FEL UNDULATOR
Authors: HUANG Z. , STUPAKOV G. , REICHE S.
Published: October 2007

Various methods have been proposed to condition an electron beam in order to reduce its emittance effect and to improve the short-wavelength free electron laser (FEL) performance. In this paper, we show that beam conditioning does not result in a complete elimination of the emittance effect in an alternating-gradient focusing FEL undulator. Using a one-dimensional model and a three-dimensional simulation code, we derive a criteria for the emittance limitation of a perfectly conditioned beam that depends on the focusing structure.
HIGH BRIGHTNESS BEAM APPLICATIONS: ENERGY RECOVERED LINACS
Authors: KRAFFT GEOFFREY A.
Published: October 2007

In the first part of the paper some general statements are made regarding applications suitable for utilizing energy recovered linacs (ERLs) by contrasting their potential performance to that of single pass linacs and storage rings. As a result of their potential for extremely good beam quality in combination with high average beam current, ERLs have been used and considered as drivers of both free electron laser and partially coherent photon sources, from THz through X-rays; as a suitable technology for high energy electron cooling; and as a continuous or semi-continuous electron beam source for high energy colliders. At present, beam requirements tend to be highly matched to end use requirements. By reviewing some of the many examples which have either been reduced to practice, or are being explored presently, one can develop an appreciation for the wide range of parameters being considered in ERL applications.
ULTRACOLD ELECTRON SOURCES
Authors: LUITEN O. J. , CLAESSENS B. J. , VAN DER GEER S. B. , REIJNDERS M. P. , TABAN G. , VREDENBREGT E. J. D.
Published: October 2007

Ultra-cold plasmas with electron temperatures of ~10 K can be created by photo-ionization just above threshold of a cloud of laser-cooled atoms. Recently it was shown 7 by GPT particle tracking simulations that an ultra-cold plasma has an enormous potential as a pulsed bright electron source. Here we discuss these results in the framework of normalized 6D brightness, which allows us to make a proper comparison both with the performance of pulsed, radio-frequency photo-emission sources and with the performance of continuous, needle-like field-emission sources. In addition we speculate on the possibility of using ultra-cold plasmas to realize quantum degenerate electron beams, constituting the ultimate limit in electron beam brightness.
HIGH BRIGHTNESS BEAMS — APPLICATIONS TO FREE-ELECTRON LASERS
Authors: REICHE SVEN
Published: October 2007

Free-Electron Lasers as high-brilliance radiation sources, rely on a high quality of the electron beam driving the FEL process. The amount of energy, transferred from the electrons to the radiation field, and thus the efficiency of the FEL depends on the provided beam parameters. The presentation discusses the impact of various beam parameter and how current designs of FEL injector try to accomplish the demands on the beam quality for reaching saturation.
CONCEPTION OF PHOTOINJECTORS FOR THE CTF3 EXPERIMENT
Authors: ROUX R.
Published: October 2007

In the framework of the CLIC Test Facility (CTF3) under development at CERN, LAL-Orsay is responsible for the construction of two photo-injectors for two different linacs. One, dedicated for the so called “drive beam linac” must fulfil very demanding specifications. The RF gun has to provide a high quality beam composed of more than 2,000 bunches containing 2.33 nC of charge each in one RF pulse. The model adopted is inspired from the CERN 3 GHz 2-1/2 cell type IV RF gun. We will summarize all the studies performed on the RF design and on the beam dynamics. The vacuum issue has been also carefully investigated. The constraints on the second photo-injector are less severe since it must be operated with one or 64 bunches of 0.5 nC each for the so called “probe beam linac”. It will also be a 2.5 cell gun at 3 GHz but its design will be substantially different with respect to the former. This last project has only recently begun and therefore we will show only the preliminary results of the RF and of the beam dynamics simulations.
SUPERCONDUCTING RF PHOTOINJECTORS: AN OVERVIEW
Authors: SEKUTOWICZ J.
Published: October 2007

R&D programs based on various approaches, at BNL, FZ-Rossendorf, Beijing University and AES generate optimism that low emittance continuous wave operating SRF-guns and injectors will be available in the near future. This contribution covers present status of these programs and it presents recently proposed alternative approach for the SRF-gun design with thin lead spot as the photo-cathode for generation of electrons in a bulk niobium cavity operating at 2K.
STATUS AND PERSPECTIVES OF PHOTOINJECTOR DEVELOPMENTS FOR HIGH BRIGHTNESS BEAMS
Authors: STEPHAN FRANK
Published: October 2007

The development and reliable operation of high brightness electron sources are key issues for next generation short wavelength light sources and a future linear collider. This paper will concentrate on photo emission based injector developments for various projects which require individual solutions and face specific problems and challenges. A selective overview of developments and experimental results will be presented demonstrating that for a large parameter range dedicated photo injectors are able to fulfill the specific stringent requirements on beam quality and other beam parameters, e.g. the time structure of the beam.
RESULTS FROM THE UCLA/FNPL UNDERDENSE PLASMA LENS EXPERIMENT
Authors: THOMPSON M. C. , BADAKOV H. , ROSENZWEIG J. B. , TRAVISH G. , EDWARDS H. , FLILLER R. , KAZAKEVICH G. M. , PIOT P. , SANTUCCI J. , LI J. , TIKHOPLAV R.
Published: October 2007

A gaussian underdense plasma lens with peak density 5 × 1012 cm −3 and a full width half maximum (FWHM) length of 2.2 cm has been used to focus a relativistic electron beam. This plasma lens is equivalent in strength to a quadrupole magnet with a 150 T/m field gradient. The lens focused a 15 MeV, 16 nC electron beam with initial dimensions σx,y ≈ 650 μ m and σz ≈ 6.5 mm onto an optical transition radiation (OTR) screen ~2 cm downstream of the lens. The average transverse area of the plasma focused electron beam was typically demagnified by a factor of 23. The evolution of the beam envelope in the area near the beam waist was measured for both round beams and asymmetric beams with x:y aspect ratios as large as 1:5. The light from the OTR screen in the round beam case was also imaged into a streak camera in order to directly measure the correlation between z and σr within the beam.
MEDICAL APPLICATION OF MULTI-BEAM COMPTON SCATTERING MONOCHROMATIC TUNABLE HARD X-RAY SOURCE
Authors: Uesaka Mitsuru , Dobashi Katsuhiro , Sakamoto Fumito , Fukasawa Atsushi , Ogino Haruyuki , Yamamoto Tomohiko , Meng De , Miyoshi Toshinobu , Urakawa Junji , Higo Toshiyasu , Akemoto Mitsuo
Published: October 2007

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo. Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35 MeV electron beam and 2.5 J/10 nsec Nd:YAG laser. In order to increase the efficiency of the X-ray yield, we adopt a laser pulse circulation system. In our case, the laser pulse circulation system can increase the X-ray intensity of up to 10 times. Main features of our scheme are to produce monochromatic tunable hard (10-40 keV) X-rays with the intensities of 108-109 photons/sec. In addition, X-ray energy can be changed with rapidly by 40 ms by introducing two different wavelength lasers (YAG fundamental (1064 nm), 2nd harmonic (532 nm)) and optical switch. This quick energy change is indispensable to living specimens and very difficult by a large SR light source and others. Dual-energy X-ray CT and subtraction X-ray CT are available to determine 3D distribution of atomic number density and electron density, and specified atomic distribution, respectively. Here, the construction status of the X-band beam line and the application plan of the hard X-ray are described and discussed.
DESIGN OF A 2 kA, 30 fs RF-PHOTOINJECTOR FOR WATERBAG COMPRESSION
Authors: VAN DER GEER S. B. , LUITEN O. J. , DE LOOS M. J.
Published: October 2007

Because uniformly filled ellipsoidal ‘waterbag’ bunches have linear self-fields in all dimensions, they do not suffer from space-charge induced brightness degradation. This in turn allows very efficient longitudinal compression of high-brightness bunches at sub or mildly relativistic energies, a parameter regime inaccessible up to now due to detrimental effects of non-linear space-charge forces. To demonstrate the feasibility of this approach, we investigate ballistic bunching of 1 MeV, 100 pC waterbag electron bunches, created in a half-cell rf-photogun, by means of a two-cell booster-compressor. Detailed GPT simulations of this table-top set-up are presented, including realistic fields, 3D space-charge effects, path-length differences and image charges at the cathode. It is shown that with a single 10MW S-band klystron and fields of 100 MV/m, 2kA peak current is attainable with a pulse duration of only 30 fs at a transverse normalized emittance of 1.5 μm.
PROPOSAL FOR A HIGH-BRIGHTNESS PULSED ELECTRON SOURCE
Authors: ZOLOTOREV M. , COMMINS E. D. , HEIFETS S. , SANNIBALE F.
Published: October 2007

We propose a novel scheme for a high-brightness pulsed electron source, which has the potential for many useful applications in electron microscopy, inverse photo-emission, low energy electron scattering experiments, and electron holography. A description of the proposed scheme is presented.
A MULTI-OBJECTIVE GENETIC ALGORITHM FOR TUNING AND RULE SELECTION TO OBTAIN ACCURATE AND COMPACT LINGUISTIC FUZZY RULE-BASED SYSTEMS
Authors: ALCALÁ R. , GACTO M. J. , HERRERA F. , ALCALÁ-FDEZ J.
Published: October 2007

This work proposes the application of Multi-Objective Genetic Algorithms to obtain Fuzzy Rule-Based Systems with a better trade-off between interpretability and accuracy in linguistic fuzzy modelling problems. To do that, we present a new post-processing method that by considering selection of rules together with tuning of membership functions gets solutions only in the Pareto zone with the highest accuracy, i.e., containing solutions with the least number of possible rules but still presenting high accuracy. This method is based on the well-known SPEA2 algorithm, applying appropriate genetic operators and including some modifications to concentrate the search in the desired Pareto zone.
AN ALTERNATIVE APPROACH TO DISCOVER GRADUAL DEPENDENCIES
Authors: BERZAL F. , CUBERO J. C. , SÁNCHEZ D. , VILA M. A. , SERRANO J. M.
Published: October 2007

In this paper we propose a new definition of gradual dependence as a special kind of association rule. We propose a way to adapt existing association rule mining algorithms for the new task of mining such dependencies, and we discuss about its complexity. Some experiments in a real database illustrate the usefulness of the approach.
A NEURO-FUZZY MODEL FOR DIMENSIONALITY REDUCTION AND ITS APPLICATION
Authors: KOLODYAZHNIY VITALIY , KLAWONN FRANK , TSCHUMITSCHEW KATHARINA
Published: October 2007

A novel neuro-fuzzy approach to nonlinear dimensionality reduction is proposed. The approach is an auto-associative modification of the Neuro-Fuzzy Kolmogorov's Network (NFKN) with a “bottleneck” hidden layer. Two training algorithms are considered. The validity of theoretical results and the advantages of the proposed model are confirmed by an experiment in nonlinear principal component analysis and an application in the visualization of high-dimensional wastewater treatment plant data.
BIBLIOMETRIC MAPPING OF THE COMPUTATIONAL INTELLIGENCE FIELD
Authors: VAN ECK NEES JAN , WALTMAN LUDO
Published: October 2007

In this paper, a bibliometric study of the computational intelligence field is presented. Bibliometric maps showing the associations between the main concepts in the field are provided for the periods 1996–2000 and 2001–2005. Both the current structure of the field and the evolution of the field over the last decade are analyzed. In addition, a number of emerging areas in the field are identified. It turns out that computational intelligence can best be seen as a field that is structured around four important types of problems, namely control problems, classification problems, regression problems, and optimization problems. Within the computational intelligence field, the neural networks and fuzzy systems subfields are fairly intertwined, whereas the evolutionary computation subfield has a relatively independent position.
Web site personalization based on link analysis and navigational patterns
Authors: Eirinaki Magdalini , Vazirgiannis Michalis
Published: October 2007

The continuous growth in the size and use of the World Wide Web imposes new methods of design and development of online information services. The need for predicting the users' needs in order to improve the usability and user retention of a Web site is more than evident and can be addressed by personalizing it. Recommendation algorithms aim at proposing “next” pages to users based on their current visit and past users' navigational patterns. In the vast majority of related algorithms, however, only the usage data is used to produce recommendations, disregarding the structural properties of the Web graph. Thus important—in terms of PageRank authority score—pages may be underrated. In this work, we present
UPR
, a PageRank-style algorithm which combines usage data and link analysis techniques for assigning probabilities to Web pages based on their importance in the Web site's navigational graph. We propose the application of a localized version of
UPR
(
l-UPR
) to personalized navigational subgraphs for online Web page ranking and recommendation. Moreover, we propose a hybrid probabilistic predictive model based on Markov models and link analysis for assigning prior probabilities in a hybrid probabilistic model. We prove, through experimentation, that this approach results in more objective and representative predictions than the ones produced from the pure usage-based approaches.
Generating semantically enriched user profiles for Web personalization
Authors: Anand Sarabjot Singh , Kearney Patricia , Shapcott Mary
Published: October 2007

Traditional collaborative filtering generates recommendations for the active user based solely on ratings of items by other users. However, most businesses today have item ontologies that provide a useful source of content descriptors that can be used to enhance the quality of recommendations generated. In this article, we present a novel approach to integrating user rating vectors with an item ontology to generate recommendations. The approach is novel in measuring similarity between users in that it first derives factors, referred to as
impacts
, driving the observed user behavior and then uses these factors within the similarity computation. In doing so, a more comprehensive user model is learned that is sensitive to the context of the user visit.

An evaluation of our recommendation algorithm was carried out using data from an online retailer of movies with over 94,000 movies, 44,000 actors, and 10,000 directors within the item knowledge base. The evaluation showed a statistically significant improvement in the prediction accuracy over traditional collaborative filtering. Additionally, the algorithm was shown to generate recommendations for visitors that belong to sparse sections of the user space, areas where traditional collaborative filtering would generally fail to generate accurate recommendations.
Toward trustworthy recommender systems
Authors: Mobasher Bamshad , Burke Robin , Bhaumik Runa , Williams Chad
Published: October 2007

Publicly accessible adaptive systems such as collaborative recommender systems present a security problem. Attackers, who cannot be readily distinguished from ordinary users, may inject biased profiles in an attempt to force a system to “adapt” in a manner advantageous to them. Such attacks may lead to a degradation of user trust in the objectivity and accuracy of the system. Recent research has begun to examine the vulnerabilities and robustness of different collaborative recommendation techniques in the face of “profile injection” attacks. In this article, we outline some of the major issues in building secure recommender systems, concentrating in particular on the modeling of attacks and their impact on various recommendation algorithms. We introduce several new attack models and perform extensive simulation-based evaluations to show which attacks are most successful and practical against common recommendation techniques. Our study shows that both user-based and item-based algorithms are highly vulnerable to specific attack models, but that hybrid algorithms may provide a higher degree of robustness. Using our formal characterization of attack models, we also introduce a novel classification-based approach for detecting attack profiles and evaluate its effectiveness in neutralizing attacks.
Adaptive hypermedia through contextualized open hypermedia structures
Authors: Bailey Christopher , Hall Wendy , Millard David E. , Weal Mark J.
Published: October 2007

The aim of this article is to produce an alternative view of the adaptive hypermedia (AH) domain from a contextually-aware open hypermedia (OH) perspective. We believe that a wide range of AH techniques can be supported with a small number of OH structures, which can be combined together to create more complex effects, possibly simplifying the development of new AH systems.

In this work we reexamine Brusilovsky's taxonomy of AH techniques from a structural OH perspective. We also show that it is possible to identify and model common structures across the taxonomy of adaptive techniques. An agent-based adaptive hypermedia system called HA
3
L is presented, which uses these OH structures to provide a straightforward implementation of a variety of adaptive hypermedia techniques. This enables us to reflect on the structural equivalence of many of the techniques, demonstrates the advantages of the OH approach, and can inform the design of future adaptive hypermedia systems.
ServiceFinder
Authors: Fang Xiao , Sheng Olivia R. Liu , Chau Michael
Published: October 2007

The rapid advancement of Internet technologies enables more and more educational institutes, companies, and government agencies to provide services, namely online services, through web portals. With hundreds of online services provided through a web portal, it is critical to design web portals, namely service portals, through which online services can be easily accessed by their consumers. This article addresses this critical issue from the perspective of service selection, that is, how to select a small number of service-links (i.e., hyperlinks pointing to online services) to be featured in the homepage of a service portal such that users can be directed to find the online services they seek most effectively. We propose a mathematically formulated metric to measure the effectiveness of the selected service-links in directing users to locate their desired online services and formally define the service selection problem. A solution method, ServiceFinder, is then proposed. Using real-world data obtained from the Utah State Government service portal, we show that ServiceFinder outperforms both the current practice of service selection and previous algorithms for adaptive website design. We also show that the performance of ServiceFinder is close to that of the optimal solution resulting from exhaustive search.
A novel XML music information retrieval method using graph invariants
Authors: Pinto Alberto , Haus Goffredo
Published: October 2007

The increasing diffusion of XML languages for the encoding of domain-specific multimedia information raises the need for new information retrieval models that can fully exploit structural information. An XML language specifically designed for music like MX allows queries to be made directly on the thematic material. The main advantage of such a system is that it can handle symbolic, notational, and audio objects at the same time through a multilayered structure. On the model side, common music information retrieval methods do not take into account the inner structure of melodic themes and the metric relationships between notes.

In this article we deal with two main topics: a novel architecture based on a new XML language for music and a new model of melodic themes based on graph theory.

This model takes advantage of particular graph invariants that can be linked to melodic themes as metadata in order to characterize all their possible modifications through specific transformations and that can be exploited in filtering algorithms. We provide a similarity function and show through an evaluation stage how it improves existing methods, particularly in the case of same-structured themes.
Reducing human interactions in Web directory searches
Authors: Gerstel Ori , Kutten Shay , Laber Eduardo Sany , Matichin Rachel , Peleg David , Pessoa Artur Alves , Souza Criston
Published: October 2007

Consider a website containing a collection of webpages with data such as in Yahoo or the Open Directory project. Each page is associated with a weight representing the frequency with which that page is accessed by users. In the tree hierarchy representation, accessing each page requires the user to travel along the path leading to it from the root. By enhancing the index tree with additional edges (hotlinks) one may reduce the access cost of the system. In other words, the hotlinks reduce the expected number of steps needed to reach a leaf page from the tree root, assuming that the user knows which hotlinks to take. The
hotlink enhancement
problem involves finding a set of hotlinks minimizing this cost.

This article proposes the first exact algorithm for the hotlink enhancement problem. This algorithm runs in polynomial time for trees with logarithmic depth. Experiments conducted with real data show that significant improvement in the expected number of accesses per search can be achieved in websites using this algorithm. These experiments also suggest that the simple and much faster heuristic proposed previously by Czyzowicz et al. [2003] creates hotlinks that are nearly optimal in the time savings they provide to the user.

The version of the hotlink enhancement problem in which the weight distribution on the leaves is unknown is discussed as well. We present a polynomial-time algorithm that is optimal for any tree for any depth.