bluuebunny/crossref_metadata_2025 huggingface dataset:
Echocardiographic Assessment of Global Ventricular Function Using the Myocardial Performance Index in Rats with Hypertrophy
Authors: Salemi Vera M.C. , Pires Mara D. , Cestari Ismar N. , Cestari Idágene A. , Picard Michael H. , Leirner Adolfo A. , Mady Charles
Published: April 2004

Abstract:  Myocardial hypertrophy is the hallmark of chronic pressure overload and the myocardial performance index (MPI) is an easily recordable measurement of Doppler time intervals. In this study, the utility of using MPI to assess the progression of hypertrophy in the aortic‐banded rat model was evaluated. Male Wistar rats (70–90 g) underwent ascending aorta constriction (n = 4) or a sham operation (n = 5). High‐resolution echocardiography was performed 4, 7, 10, and 12 weeks after the surgery. Over this follow‐up interval, animals in the aortic‐banded group demonstrated an increase in their mean left ventricular (LV) mass and MPI compared with controls. MPI  reflects  ventricular  performance  in  small  animals with LV hypertrophy, showing alterations early after aorta constriction.
Tobacco smoking and dental periapical condition
Authors: Bergström Jan , Babcan Juraj , Eliasson Sören
Published: March 2004

The relation between smoking and apical periodontitis has been little studied to date. The aim of the present study was to investigate whether tobacco smoking might be associated with the prevalence or severity of periapical lesions. A total of 247 individuals, 81 current smokers, 63 former smokers, and 103 non‐smokers participated in the study. The periapical condition was expressed as the number and percentage of radiographically detectable lesions and, in addition, as a severity index. The overall prevalence of apical periodontitis was 52% and the overall prevalence of endodontic treatment 58%. There was no significant influence of smoking on the prevalence of either apical periodontitis or endodontic treatment. The mean number (percentage) of periapical lesions per person was 1.9 (6%) in current smokers, 1.5 (4%) in former smokers, and 1.0 (3%) in non‐smokers. Controlling for age, the association between smoking and periapical lesions was not statistically significant. The mean periapical severity index including all teeth, or teeth affected by periapical lesions alone, did not significantly differ between smoking groups. It is concluded that the present observations do not lend support to the assumption that tobacco smoking is associated with apical periodontitis.
Relation of different measures of psychological characteristics to oral health habits, diabetes adherence and related clinical variables among diabetic patients
Authors: Syrjälä Anna‐Maija H. , Ylöstalo Pekka , Niskanen Mirka C. , Knuuttila Matti L. E.
Published: March 2004

Among diabetic patients, oral health status and oral health behavior have been found to relate to metabolic control. The aim was to analyse which psychological characteristics, i.e. intention, self‐efficacy, locus of control or self‐esteem related to health behavior most comprehensively explain oral health habits, diabetes adherence, dental caries, deepened periodontal pockets, and the metabolic parameter HbA1c (glycosylated hemoglobin). The study subjects consisted of a group of 149 insulin‐dependent diabetic patients. Data were obtained from self‐completed questionnaires. The proportions of variance explained by the linear regression model were used as measures in the comparisons. It was found that oral health habits and diabetes adherence correlated. Both dental and diabetes self‐efficacy scores were related to oral health habits and diabetes adherence. This indicates that self‐efficacy is the best overall determinant of various health behavior practices. The ability of psychological characteristics to explain oral health was limited. Improvement of self‐efficacy therefore may have a positive effect on various aspects of health behaviors.
Effects of 3,4‐methylenedioxymethamphetamine (‘Ecstasy’) on the jaw‐opening reflex and on the α2‐adrenoceptors which regulate this reflex in the anesthetized rat
Authors: Arrue Aurora , Gómez Francisco M. , Giralt M. Teresa
Published: March 2004

Bruxism, principally jaw clenching, is frequently observed in users of the recreational drug 3,4‐methylenedioxymethamphetamine (MDMA). It has been suggested that during bruxism a reduction of the activity of oral protective reflexes occurs. In this study we investigated the effects of intravenously administered MDMA on the digastric electromyographic responses elicited by orofacial electrical stimulation in the rat. We also assessed the effects of either the administration of a single dose (20 mg kg−1, s.c.) or repeated doses of MDMA (same dose, twice a day, for 4 d) on the jaw‐opening reflex (JOR) and on the sensitivity of the α2‐adrenoceptors which, in an inhibitory way, regulate it. Increasing doses of MDMA (1–29440 µg kg−1) induced an incomplete inhibition of JOR and 50% inhibition (ED50) at 2550 µg kg−1; maximal inhibition was 88%. The repeated treatment with MDMA led to an enhancement of the inhibition of JOR induced by the α2‐agonist, clonidine (ED50 was reduced by 77%), indicating an increased sensitivity of the α2‐adrenoceptors. This study shows that the intravenous administration of MDMA reduces the JOR while repeated doses of the drug enhance the inhibitory noradrenergic mechanisms which regulate the reflex. The results also allow speculation that a reduction of JOR may underlie the occurrence of episodes of bruxism in MDMA users.
Cytotoxicity and sealing properties of four classes of endodontic sealers evaluated by succinic dehydrogenase activity and confocal laser scanning microscopy
Authors: Bouillaguet Serge , Wataha John C. , Lockwood Petra E. , Galgano Camillo , Golay Antoine , Krejci Ivo
Published: March 2004

The objectives of this study were to evaluate the cytotoxicity and sealing properties of four classes of endodontic sealers (PCS/Kerr, RoekoSeal/Roeko, TopSeal/Dentsply, and EndoREZ/Ultradent). For cytotoxicity testing (MTT method), the materials were either placed immediately in contact with cultured cells or 24 h after setting, then evaluated at three subsequent time points (24 h, 48 h, or 1 wk). For the leakage study, extracted human roots were obturated with acrylic cones and sealers and immersed for 48 h into rhodamine‐labeled lipopolysaccharide. The roots were then observed under a confocal laser scanning microscope to estimate (semiquantitatively) the presence of the rhodamine‐lipopolysaccharide (LPS) inside the canal. The results showed that cytotoxicity generally increased with time, and that most materials pose significant cytotoxic risks, particularly in the freshly mixed condition. Further, all materials showed significant leakage although there was large variation among teeth. Overall, the silicon‐based material (Roeko Seal) was less cytotoxic and more effective in sealing root canals against LPS leakage than other materials.
Correlation of stress and strain profiles and the distribution of osteoclastic cells induced by orthodontic loading in rat
Authors: Kawarizadeh Afshar , Bourauel Christoph , Zhang Dongliang , Götz Werner , Jäger Andreas
Published: March 2004

The aim of this study was to investigate whether stress or strain within the periodontal ligament (PDL), or rather in the bone, plays a role in initiating biological responses in orthodontic tooth movement. The upper first molars of 11 Wistar rats were moved mesially with a closed nickel titanium alloy coil spring for 3–12 d and three rats served as controls. After preparation of the maxillae for paraffin histology, tartrate‐resistant acid phosphatase (TRAP) activity was evaluated to detect osteoclasts and their mononuclear precursors in four regions around the mesial root. Based on histological sections, finite element models were developed. The stress/strain distributions associated with the orthodontic loading were determined in the alveolar bone and in the PDL and compared with the osteoclast distributions. In the PDL, the normal stresses and strains were compressive (negative) in regions where the number of osteoclasts was highest, whereas the positive normal tensile stresses and strains were coincident with regions with small numbers of osteoclasts. The results indicate a direct correlation of the calculated stress/strain values in the PDL with the distributions of osteoclasts in the alveolar bone and PDL. Thus, these seem to be the dominant mechanical factor of tissue reaction to orthodontic force application, whereas the mechanical loading of the bone does not seem to play a role in orthodontic bone remodeling.
A new method for volumetric measurement of orthodontically induced root resorption craters
Authors: Chan Eugene K. M. , Darendeliler M. Ali , Petocz Peter , Jones Allan S.
Published: March 2004

This method was designed to quantify root resorption on human premolar root surfaces induced by orthodontic forces by volume. Light (25 g) or heavy (225 g) orthodontic forces were applied to 20 first maxillary premolars in 10 human subjects. The contralateral teeth of the subjects served as controls. All teeth were extracted after 28 d of experimentation and prepared for imaging. A pair of stereo scanning electron microscopy (SEM) images (±3°) of resorption craters was captured and imported into an image analysis software package. The images were aligned and grayscale depth maps of the craters were generated. Correction for errors due to residual tilt and curvature of the cementum surface using shading correction was performed. Thresholding was used to obtain a measure of both the cementum surface height and the average depth of the crater. The depth of the crater was the difference in these values. Crater volumes were obtained by multiplication of the average of this difference by area of the crater. Calibration of this volumetric measurement against standardized calculated known volumes on metallic rods showed good accuracy and reproducibility. In the experimental teeth, heavy forces caused threefold more resorption than light forces (P < 0.01). There was also more root resorption evident in the experimental teeth compared with the control teeth in both the light and heavy force groups.
Survival rate of mono‐ceramic and ceramic‐core CAD/CAM‐generated anterior crowns over 2–5 years
Authors: Bindl Andreas , Mörmann Werner H.
Published: March 2004

Anterior mono‐ceramic (Mk II, n = 18) and ceramic core (In‐Ceram Spinell, n = 18) crowns were CAD/CAM‐fabricated using Vitablocs with the Cerec 2 CAD/CAM system and bonded in 24 patients. All crowns were rated using modified United States Public Health Services (USPHS) criteria at baseline and after a service time of 2–5 years. Survival of the crowns, regarding fracture, was analysed (Kaplan–Meier) after 44.7 ± 10.3 months. Gingival health at crowns was assessed using plaque and bleeding scores. One core crown and one mono‐ceramic crown had fractured after 42.5 months and 12 months, respectively, with survival rates of 91.7% for In‐Ceram Spinell and 94.4% for Mk II; the difference was not statistically significant. Between baseline and follow‐up examinations, non‐significant shifts from A‐ to B‐ratings occurred, particularly for marginal adaptation, for both crown types. Plaque and bleeding scores did not differ between the ceramic crown types but showed significantly less plaque and less bleeding at ceramic crowns than at control teeth at follow‐up. The clinical performance of mono‐ceramic crowns was judged to be similar to that of ceramic core crowns.
Involvement of matrix metalloproteinases in the onset of dentin mineralization
Authors: Fanchon Stephanie , Bourd Katia , Septier Dominique , Everts Vincent , Beertsen Wouter , Menashi Suzanne , Goldberg Michel
Published: March 2004

In order to study the involvement of matrix metalloproteinases (MMPs) on dentin formation and mineralization, day 18 embryonic mouse tooth germs were cultured for 10 d in the presence or absence of Marimastat, a general MMP inhibitor, or CT1166, a more selective inhibitor of gelatinases (MMP‐2 and MMP‐9) and stromelysin‐1 (MMP‐3). With Marimastat a dose‐dependent increase in thickness of the predentin layer and a decreased mineralization of dentin were observed. At the highest concentration of the inhibitor used, enamel formation had ceased. With CT1166, these effects were already apparent at the lowest concentration used. Western blot analyses demonstrated that the two inhibitors inhibited the expression of enamelysin (MMP‐20). These observations indicate that MMPs (possibly MMP‐2, ‐3, ‐9 and/or ‐20) play a role in the onset of dentin mineralization. The lack of enamel formation was possibly due to diffusion of amelogenin from its normal site of apposition. The protein clearly was not retained at the surface of the non‐mineralized dentin layer, and immunopositive amelogenin accumulated in the odontoblast compartment. The diffusion of enamel proteins and the accumulation revealed by immunolabeling of two small leucine‐rich proteoglycans, decorin and biglycan, in the predentin may have contributed to impaired dentin mineralization.
Enteric neural crest‐derived cells and neural stem cells: biology and therapeutic potential
Authors: Burns A. J. , Pasricha P. J. , Young H. M.
Published: April 2004

The enteric nervous system arises from two regions of the neural crest; the vagal neural crest which gives rise to the vast majority of enteric neurones throughout the gastrointestinal tract, and the sacral neural crest which contributes a smaller number of cells that are mainly distributed within the hindgut. The migration of vagal neural crest cells into, and along the gut is promoted by GDNF, which is expressed by the gut mesenchyme and is the ligand for the Ret/GFRα1 signalling complex present on migrating vagal‐derived crest cells. Sacral neural crest cells enter the gut after it has been colonized by vagal neural crest cells, but the molecular control of sacral neural crest cell development has yet to be elucidated. Under the influence of both intrinsic and extrinsic cues, neural crest cells differentiate into glia and different types of enteric neurones at different developmental stages. Recently, the potential for neural stem cells to form an enteric nervous system has been examined, with the ultimate aim of using neural stem cells as a therapeutic strategy for some gut disorders where enteric neurones are reduced or absent.
Ionic conductances involved in generation and propagation of electrical slow waves in phasic gastrointestinal muscles
Authors: Sanders K. M. , Koh S. D. , Ördög T. , Ward S. M.
Published: April 2004

Considerable work has led many to conclude that interstitial cells of Cajal (ICC) are the pacemaker cells of the gastrointestinal (GI) tract. These cells form electrically coupled networks within the pacemaker regions of the GI tract, and ICC are electrically coupled to smooth muscle cells. ICC express unique ion channels that periodically produce inward (pacemaker) currents. Recent work has suggested that the inward current is produced by a calcium (Ca2+)‐regulated, nonselective cation conductance. Channels responsible for this conductance oscillate in open probability in response to the periodic drop in intracellular Ca2+ concentration during the slow wave cycle. Pacemaker activity generates slow waves that are propagated actively through ICC networks. Depolarization coordinates the pacemaker activity through the ICC network by activating a dihydropyridine‐resistant Ca2+ conductance. Entry of small amounts of Ca2+ into ICC entrains spontaneous pacemaker activity and produces cell‐to‐cell propagation of slow waves. This review discusses the mechanisms and conductances involved in generation and propagation of electrical slow waves in ICC.
Ion channels in interstitial cells of Cajal as targets for neurotransmitter action
Authors: Huizinga J. D. , Golden C. M. , Zhu Y. , White E. J.
Published: April 2004

Interstitial cells of Cajal (ICC) are involved in generation of gut pacemaker activity, neurotransmission and stretch sensation. Pacemaker ICC exhibit spontaneous cyclic calcium oscillations that are in synchrony with its pacemaker activity. The spontaneous rhythmic inward currents in ICC that underlie gut pacemaker activity are linked to this calcium oscillation. It is probable that more than one type of channel contributes to the inward current with a high conductance chloride channel and a nonselective cation channel being the main candidates. The activation of these channels is linked to intracellular calcium cycling mechanism and involves inositol 1,4,5‐trisphosphate (IP3)‐mediated calcium release from the sarcoplasmic reticulum, and calcium uptake into mitochondria. This ion channel activity is modulated by signalling through neurotransmitter receptors, including the NK1 receptor. This finding and the presence of other neurotransmitter receptor mRNA transcripts indicates that ion channels in ICC are targets for neurotransmitter action. The ether‐a‐go‐go‐related (ERG) K channel is probably the most important K channel contributing to the resting membrane potential and excitability of the ICC. Many ion channels in ICC are regulated by second messenger systems which makes them highly susceptible to neurotransmitter modulation.
Role of vasoactive intestinal peptide and inflammatory mediators in enteric neuronal plasticity
Authors: Ekblad E. , Bauer A. J.
Published: April 2004

Complex circuits involving both local intrinsic neurones (i.e. enteric nervous system; ENS) and extrinsic neurones achieve nervous control of digestive functions. The ENS is comprised of many functionally different types of neurons: sensory neurons, interneurons and secreto‐motor neurons. Each neuronal population is required to manifest local reflex behavior and is central to the regulation of both motor and secretory activities. It must be emphasized, however, that not only muscle and secretory cells but also other intestinal cells are targeted by enteric neurones, i.e. endocrine cells, interstitial cells of Cajal, immune cells, blood vessels and enteric glia. In addition to the ENS the gastrointestinal tract receives an extrinsic innervation by sympathetic, parasympathetic and sensory fibres. Neuronal projections from the intestine to prevertebral ganglia also exist. Taken together, the picture of a complex nervous regulation of digestive functions highly integrated with the central nervous system and the rest of the autonomic nervous system has emerged. The ENS is adaptive and plastic, but also vulnerable, system and ENS disturbances may be of pathogenic importance in functional bowel disease. In particular the interplay between the enteric neurones and the immune cells is suggested to be of crucial importance. The review discusses possible roles of the mediators vasoactive intestinal peptide (VIP) and prostanoids in ENS plasticity in response to injury and inflammation.
Re‐innervation and recovery of rat soleus muscle and motor unit function after nerve crush
Authors: Leterme D , Tyč F
Published: April 2004

In this study we have investigated the effects of peripheral nerve crush on the contractile properties of the adult rat soleus muscle. The soleus nerve was crushed close to the muscle and functional re‐innervation was assessed by the measurement of the force produced by contraction induced by electrical nerve stimulation. Whole soleus muscle and single motor unit (MU) properties were studied at increasing re‐innervation times 7–56 days after crush. Results showed progressive re‐innervation as 50% of the axotomized motoneurones had re‐innervated their muscle 7 days after crush, 72% at 14 days and re‐innervation was complete at 28 days. The force parameters recovered more slowly. Tetanic contractions faded at high frequency stimulation, which did not occur in the control muscle. This disruption in the tetanic response was more pronounced in single MUs. Our results demonstrate for the first time a process of progressive axonal re‐innervation by the axotomized motoneurones and provide a functional picture of the effective restoration of the neuromuscular function.
Human single muscle fibre function with 84 day bed‐rest and resistance exercise
Authors: Trappe Scott , Trappe Todd , Gallagher Philip , Harber Matthew , Alkner Bjorn , Tesch Per
Published: April 2004

Muscle biopsies were obtained from the vastus lateralis before and after 84 days of bed‐rest from six control (BR) and six resistance‐exercised (BRE) men to examine slow‐ and fast‐twitch muscle fibre contractile function. BR did not exercise during bed‐rest and had a 17 and 40% decrease in whole muscle size and function, respectively. The BRE group performed four sets of seven maximal concentric and eccentric supine squats 2–3 days per week (every third day) that maintained whole muscle strength and size. Slow (MHC I) and fast (MHC IIa) muscle fibres were studied at 15°C for diameter, peak force (Po), contractile velocity (Vo) and force–power parameters. SDS‐PAGE was performed on each single fibre after the functional experiments to determine MHC isoform composition. MHC I and IIa BR fibres were, respectively, 15 and 8% smaller, 46 and 25% weaker (Po), 21 and 6% slower (Vo), and 54 and 24% less powerful after bed‐rest (P < 0.05). BR MHC I and IIa Po and power normalized to cell size were lower (P < 0.05). BRE MHC I fibres showed no change in size or Vo after bed‐rest; however, Po was 19% lower (P < 0.05), resulting in 20 and 30% declines (P < 0.05) in normalized Po and power, respectively. BRE MHC IIa fibres showed no change in size, Po and power after bed‐rest, while Vo was elevated 13% (P < 0.05). BRE MHC IIa normalized Po and power were 10 and 15% lower (P < 0.05), respectively. MHC isoform composition shifted away from MHC I fibres, resulting in an increase (P < 0.05) in MHC I/IIa (BR and BRE) and MHC IIa/IIx (BR only) fibres. These data show that the contractile function of the MHC I fibres was more affected by bed‐rest and less influenced by the resistance exercise protocol than the MHC IIa fibres. Considering the large differences in power of human MHC I and IIa muscle fibres (5‐ to 6‐fold), the maintenance of whole muscle function with the resistance exercise programme is probably explained by (1) the maintenance of MHC IIa power and (2) the shift from slow to fast (MHC I → MHC I/IIa) in single fibre MHC isoform composition.
Paleomagnetism and UPb geochronology of the 2.17 Ga Biscotasing dyke swarm, Ontario, Canada: evidence for vertical-axis crustal rotation across the Kapuskasing Zone
Authors: Halls Henry C , Davis Donald W
Published: March 2004

UPb dates on baddeleyite yield ages of 2167.8 ± 2.2 and 2171.6 ± 1.2 Ma on two northeast-trending dykes west of the Kapuskasing Zone in Ontario, Canada. These ages identify the dykes as belonging to the Biscotasing dyke swarm east of the Kapuskasing Zone, which was previously dated at 2166.7 ± 1.4 Ma by UPb on baddeleyite and zircon. The new dates show that the Biscotasing swarm was emplaced over an area of at least 300 000 km2, much larger than hitherto suspected, and in a geologically short period of time of about 5 million years. A comparison of paleomagnetic data from Biscotasing and 2.45 Ga Matachewan dykes on either side of the Kapuskasing Zone suggests that the western half of the Superior Province has rotated about 10°20° counterclockwise relative to the eastern half across the Kapuskasing Zone. This movement may have been accompanied by rifting farther north which ultimately led to the Paleoproterozoic embayment, underlying Hudson Bay, that gives the Superior Province its characteristic butterfly-shaped outline.
Postglacial emergence of Amund and Ellef Ringnes islands, Nunavut: implications for the northwest sector of the Innuitian Ice Sheet
Authors: Atkinson Nigel , England John
Published: March 2004

This paper presents relative sea-level curves from Amund and Ellef Ringnes islands, northwest Queen Elizabeth Islands. These curves are of exponential form and record continuous, ongoing Holocene emergence, although northwest Ellef Ringnes Island is experiencing a late Holocene transgression. Isobases drawn on postglacial shorelines rise southeastward towards an uplift centre in Norwegian Bay. These suggest the Ringnes Islands occupied the northwest radius of the Innuitian uplift, which is congruent with glacial geological evidence suggesting parts of the Ringnes Islands were covered by the Late Wisconsinan Innuitian Ice Sheet. The isobases provide a provisional reconstruction of glacioisostatic recovery within the northwest Innuitian uplift. Their pattern supports earlier reconstructions that maximum Late Wisconsinan ice thickness occurred across Norwegian Bay, marking the position of an ice divide, which is consistent with ice-flow features on Amund Ringnes Island. They record the diminishing thickness of the Innuitian Ice Sheet from Norwegian Bay to the Arctic Ocean. The absence of an isobase embayment across the Ringnes Islands suggests a relatively uniform ice load across both islands and Hassel and Massey sounds. Parallel isobases across Peary Channel indicate this ice load extended beyond Massey Sound, although their northward deflection suggests an increasing influence of the former Axel Heiberg Island ice load.
A reappraisal of the ornithischian dinosaur Amtosaurus magnus Kurzanov and Tumanova 1978, with comments on the status of A. archibaldi Averianov 2002
Authors: Parish Jolyon C , Barrett Paul M
Published: March 2004

A fragmentary braincase from the Baynshirenskaya Svita (CenomanianTuronian) of Amtgay, Omnogov, People's Republic of Mongolia was described as the holotype specimen of the ankylosaurid dinosaur, Amtosaurus magnus Kurzanov and Tumanova 1978. However, the validity of this genus has been questioned by several authors. Recently, a second species, based on a fragmentary specimen consisting of a braincase and partial skull roof, was assigned to Amtosaurus as A. archibaldi Averianov 2002. Here we re-assess the status of Amtosaurus and of the referred species, A. archibaldi. We conclude that "Amtosaurus magnus" is a nomen dubium that should be regarded as Ornithischia indeterminate. However, "A." archibaldi is a valid taxon, characterized by an autapomorphic feature of the skull roof, and we refer this species to the new genus Bissektipelta.
Little Ice Age glacial activity in Strathcona Provincial Park, Vancouver Island, British Columbia, Canada
Authors: Lewis Dave H , Smith Dan J
Published: March 2004

Dendroglaciological and lichenometric techniques are used to establish the Little Ice Age (LIA) history of two glaciers (Colonel Foster and Septimus) in Strathcona Provincial Park, Vancouver Island, British Columbia. Our lichenometric investigations were preceded by the development of a locally calibrated Rhizocarpon geographicum growth curve (17081998 A.D.). Documentation of a 34-year ecesis interval for both trees and lichen greatly reduces one of the main uncertainties in using geobotanical methods for dating LIA landforms. The moraine dates provided, therefore, give a good approximation of the shift in climate conditions that lead to the retreat of the glaciers and subsequent moraine stabilization. Geobotanical evidence records three synchronous episodes of LIA moraine deposition at both glaciers: two prominent moraines at each site are dated to the early 1700s and late 1800s, with a third, smaller moraine dated to the mid 1930s. Moraines deposited prior to 1397 A.D. were also recorded at Colonel Foster Glacier; however, precise dating of these moraines was not possible. The moraine records from Strathcona Provincial Park suggest two possible modes of glacier response: (i) synchronous responses to larger-scale climatic forcing, and (ii) asynchronous responses to local factors such as microclimate, topography, and glacier geometry. The Vancouver Island LIA record was evaluated in the context of LIA results from the Pacific North American (PNA) Cordillera. It compares well with regional moraine records from coastal British Columbia, Washington, Alaska, and the Canadian Rocky Mountains, suggesting a regional response of PNA glaciers to climate change associated with the LIA.
Peat-forming history of the ancestral Souris mire (Palaeocene), Ravenscrag Formation, southern Saskatchewan, Canada
Authors: Frank M C , Bend S L
Published: March 2004

Analysis of the Palaeocene Souris Lignite (northern Williston Basin) using coal petrology and palynology reveals the existence of seven different mire types forming six cycles of varying thickness and composition. The order of mire types within the individual cycles allows an idealized mire type succession to be defined. The principle factor driving the idealized mire type succession is decreasing water depth within the peat-forming environment (terrestrialization), which leads to an increase in species diversity and a change in floral character from ferns→ angiosperms→ gymnosperms. Increases in water depth are the primary agent responsible for the termination of individual cycles in the ancestral Souris mire. Changes in nutrient status of the mire may also promote major changes in the floral assemblage, contributing to cycle termination. Comparison of densinite:ulminite ratios for the central part of the Souris seam shows an overall decrease in the degree of humification south-westward, indicating increased subsidence towards the Williston Basin centre, where seam partings are more common. Fern-rich mire types dominate throughout most of the sampled part of the Souris seam and such mires have been interpreted as representing transitional stages in both modern and Tertiary peat-forming environments. Previous analysis of other parts of the Souris seam has revealed areas dominated by Taxodium forest mires, representing more stable environments. The co-existence of transitional and stable environments suggests that the ancestral Souris mire may have been deposited during the onset of the closing stages of Palaeocene peat formation in the northern part of the Williston Basin.
Linearized quantities in transversely isotropic media
Authors: Daley P F , Lines L R
Published: March 2004

This paper advocates a modified parameterization for transversely isotropic (TI) media in seismology. Transversely isotropic media may be parameterized by the reference quasi-compressional (qP) and quasi-shear (qSV) velocities, α and β, together with the two parameters, ε and δ. These last two variables account for the deviation of the coupled qP and qSV modes of wave propagation from the isotropic case. The dimensionless quantity ε is a measure of the ellipticity of the qP wavefront. The "strange" parameter δ has been employed as a measure of deviation of the qP wavefront or slowness surface from an ellipsoid of revolution and also of the qSV wavefront or slowness surface from a sphere. As the parameter δ has been described as "conceptually inaccessible"; it is logical to determine an alternative characterization in physically realizable quantities. As in the earlier literature, the defining parameter for the degree of ellipticity of the qP slowness or energy surface in a TI medium is chosen here to be ε. In addition, the deviation of both the qP and qSV surfaces from the degenerate ellipsoidal case will be specified here as σ. An examination of the linearized phase (wavefront normal) velocities, and the linearized PP and SVSV reflection coefficients at an interface between two TI media is undertaken to emphasize the merits of this modified parameterization. All formulae used here have appeared in one form or another in the cited literature. In this paper, a reformulation of existing equations as functions of the two independent variables, (ε, σ), is presented. This results in a more physically realizable context for the linearized formulae.
Biostratigraphical and ecostratigraphical significance of Tremadoc (Ordovician) graptolite faunas from the Misty Creek Embayment and Selwyn Basin in Yukon and Northwest Territories
Authors: Jackson D E , Norford B S
Published: March 2004

Graptolite zones of early and late Tremadoc ages are described from the Elmer Creek Formation in the Selwyn Basin and from the Duo Lake Formation in the Misty Creek Embayment. In ascending order, these are: Staurograptus dichotomus, Anisograptus matanensis, Adelograptus cf. A. tenellus and Aorograptus victoriae Biozones. The uppermost zone embraces the Adelograptus antiquus Biozone, Kiaerograptus? pritchardi Biozone, and the Paradelograptus kinnegraptoides Biozone in the Richardson Trough. Twenty five species are recorded and fourteen species are described, including the first record of the Rhabdinopora fauna in the early Tremadoc of northwest Canada and Kiaerograptus magnus Williams and Stevens and Paratemnograptus isolatus Williams and Stevens in the late Tremadoc. When modifications to Cooper's (1999) ecostratigraphic model are made based on data from Yukon and Northwest Territories, the upper slope biotope and lower slope  ocean-floor biotope become so similar that there is little basis for recognising both biotopes.
Conodont zonation across the PermianTriassic boundary at the Xiakou section, Yichang city, Hubei Province and its correlation with the Global Stratotype Section and Point of the PTB
Authors: Guoqing Wang , Wenchen Xia
Published: March 2004

Xiakou section is situated north of the central Yangtze platform with successive Late Permian to Early Triassic strata, thicker than the Global Stratotype Section and Point (GSSP) of the PermianTriassic boundary (PTB). We recognized three conodont zones across the PTB in this section by high-precision biostratigraphy. They are the Hindeodus latidentatus  Clarkina meishanensis Zone, Hindeodus parvus Zone, and Isarcicella isarcica Zone in ascending order, which correspond well with the GSSP. The present biostratigraphic work on Xiakou section certainly confirmed the conodont zonation through the PTB at the GSSP and also testified to the correctness of the PTB demarcation in Xiakou section. Based on this precise demarcation of the PTB, the appearance of a clay layer, bed ZSJI266, just beneath the PTB should be an important advantage over the GSSP, because this clay layer approaches to the PTB much in contrast with those two clay layers, bed 26 and bed 28, in the GSSP. Therefore, the radiometric isotopic dating in bed ZSJI266 at Xiakou section should give a more accurate age for the PTB.
INVESTIGATION OF LIGHT SCATTERING AND DYNAMIC PROGRESS IN SOLUTION USING A NEAR-FIELD OPTICAL MICROSCOPE
Authors: XIANG SHI-BIAO , ZHANG TIAN-HAO , XIANG XU , YAN CAI-FAN , ZHANG CHUN-PING
Published: March 2004

The local near-field light scattering and the series dynamic progress of dyestuff PAN particles in solution were investigated taking advantage of optical fiber probe and the near-field detection techniques, including the dissolving and crystallizing progress, Brownian movement and the statistical distribution of particles. Some useful and interesting results were obtained, and are in good agreement with the theoretical analysis. These findings will contribute to the research of near-field optics in a liquid environment as well as provide direct and valuable results for statistical physics.
EFFECTS OF REORTHOGONALIZATION: USING RECURSION METHOD IN SOME FINITE SYSTEMS
Authors: CHEN JIANGWEI , WAN XIANGANG , DONG JINMING
Published: March 2004

Using the recursion method in some finite systems, such as C 78, C 82, etc., we find that we cannot obtain sufficient small recursion coefficients bn+1 to cut off the calculation due to the accumulation of rounding errors; and this problem can be avoided conveniently by making the newly gained state orthogonal to the preceding states. Furthermore, our calculations show that, for low symmetrical systems, reorthogonalization is necessary to calculate the correct density of states (DOS). The similar asymptotic behaviors between the finite system and the infinite system indicate that our work may be also useful for applying recursion method in infinite systems.
THE INFLUENCE OF ATOMIC SUBSTITUTIONS ON DISSIPATION PROCESSES IN (Bi,Pb):2223 SUPERCONDUCTOR
Authors: POP V.
Published: March 2004

Bulk (Bi,Pb)(Sr,Ba) :2223 samples were prepared by the solid state reaction method. The intergranular dissipation processes of these samples were studied by complex susceptibilities measurements as a function of temperature and AC field amplitude. The partial substitution of Ca by x=0.01 Er induces an increase in the intergranular pinning force density and the intergranular critical current density J cj . The J cJ (T) dependence near T c agrees with assumptions about SNS intergrain junctions.
PRESERVING RECOMMENDER ACCURACY AND DIVERSITY IN SPARSE DATASETS
Authors: SULLIVAN DERRY O' , SMYTH BARRY , WILSON DAVID
Published: April 2004

Recommender systems combine research from user profiling, information filtering and artificial intelligence to provide users with more intelligent information access. They have proven to be useful in a range of Internet and e-commerce applications. Recent research has shown that a content-based (or case-based) perspective on collaborative filtering for recommendation can provide significant benefits in decision support accuracy over traditional collaborative techniques, particularly as dataset sparsity increases. These benefits derive both from the use of more sophisticated case-based similarity metrics and from the proactive maintenance of item similarity knowledge using data mining. This article presents a natural next step in this ongoing research to improve the quality of recommender systems by validating these findings in the context of more complex models of collaborative filtering, as well as by demonstrating that such techniques also preserve recommendation diversity, one of the key issues affecting traditional recommender systems.
IMPACT OF FRACTAL DIMENSION IN THE DESIGN OF MULTI-RESONANT FRACTAL ANTENNAS
Authors: VINOY K. J. , ABRAHAM JOSE K. , VARADAN V. K.
Published: March 2004

During the last few decades, fractal geometries have found numerous applications in several fields of science and engineering such as geology, atmospheric sciences, forest sciences, physiology and electromagnetics. Although the very fractal nature of these geometries have been the impetus for their application in many of these areas, a direct quantifiable link between a fractal property such as dimension and antenna characteristics has been elusive thus far. In this paper, the variations in the input characteristics of multi-resonant antennas based on generalizations of Koch curves and fractal trees are examined by numerical simulations. Schemes for such generalizations of these geometries to vary their fractal dimensions are presented. These variations are found to have a direct influence on the primary resonant frequency, the input resistance at this resonance, and ratios resonant frequencies of these antennas. It is expected that these findings would further enhance the popularity of the study of fractals.
SCALING LAW FOR THE DISTRIBUTION OF FLUCTUATIONS IN SHARE VOLUME
Authors: KAIZOJI TAISEI , NUKI MASAHIDE
Published: March 2004

We show power-scaling behaviors for fluctuations in share volume, which no other studies have done so far. After analyzing a database of the daily transactions for all securities listed on the Tokyo Stock Exchange, we selected 1050 large companies that each had an unbroken series of daily trading activity from January 1975 to January 2002. We found that the cumulative distributions of daily fluctuations in share volumes can be well described by a power-law decay, and that the cumulative distributions for almost all of the companies can be characterized by an exponent within the stable Lévy domain 0 < α < 2. Furthermore, more than 35% of the cumulative distributions can be well approximated by Zipf's law, i.e. the cumulative distributions have an exponent close to unity.
THE FRACTAL APPROACH AS A TOOL TO UNDERSTAND ASYMPTOMATIC BRAIN HYPERINTENSE MRI SIGNALS
Authors: BALESTRA COSTANTINO , MARRONI ALESSANDRO , FARKAS BRIGITTE , PEETRONS PHILIPPE , VANDERSCHUEREN FRÉDÉRIC , DUBOC EMILIE , SNOECK THYL , GERMONPRÉ PETER
Published: March 2004

The prevalence of a Patent Foramen Ovale is described in merely 30% of the asymptomatic population. This patency has been shown to be an increasing risk factor for paradoxical cerebral embolization. Some desaturation or decompression situations in human activities such as scuba diving or altitude flight are prone to provoke embolisations. The association with the presence of a patent Foramen Ovale and the onset of cerebral decompression sickness seems to be presenting an odds ratio value of about 5.1.1 The presence of asymptomatic brain lesion-like "spots" has been investigated in a randomized population of diving individuals (n=42 randomized out of 200). The inclusion criteria were drastic and included: age (less than 41 years of age); diving experience (more than 200 logged dives); no decompression sickness episodes; no contraindications for the MRI examination; and no known central nervous system conditions. Data of the magnetic resonance investigation of the brain has been performed in 42 (diving) volunteers fully informed on the experimental procedures. The statistical comparison (Anova test after Kolmogorov-Smirnov compatibility testing and Neuman–Keuls discriminant post-test) of the fractal dimension obtained by means of the box counting method with the slope analysis (Harfa fractal analysis program). The comparison was performed with known pathological images such as multiple sclerosis (a pathology not emerging from vascular problems), ischemic thrombotic lesions (vascular problem), diver's asymptomatic brain spots, and the arteriography of the internal carotid in non-pathological humans (clearly vascular). The statistical difference (p<0.001) between the vascular related images, as well as the absence of statistical difference (p>0.05) with the non-vascular spots images advocates with a non-vascular origin of the diver's asymptomatic spots and thus the link between the patency of the cardiac Foramen Ovale and the brain "spots" seems not to be as clear as it was believed.
SURFACE CHARACTERIZATION OF REPROCESSED SINGLE-USE MEDICAL CATHETERS BY FRACTAL MASS DIMENSION
Authors: SCANDURRA ADRIANA G. , ARIZMENDI C. M. , CUADRADO TERESITA R. , GRANADOS D. L.
Published: March 2004

Reprocessing of single-use medical devices is an issue of concern and discussion due to infection risk and operation failure. Cleaning procedures and sterilization processes can produce structural changes and relevant topographical alteration of the biomedical device surfaces which may activate mechanisms able to cause unwanted biological response. Atomic Force Microscopy analysis (AFM) to measure Poly(vinyl chloride) (PVC) catheters surface roughness variation along successive sterilization cycles was applied. In this work, the relation between the number of reprocessing cycles and the fractal mass dimension of reprocessed catheter surface microscopic images is studied.
FRACTALS TEXT MINING USING BIBLIOMETRICS AND DATABASE TOMOGRAPHY
Authors: KOSTOFF RONALD N. , SHLESINGER MICHAEL F. , MALPOHL GUIDO
Published: March 2004

Database Tomography (DT) is a textual database analysis system consisting of two major components: (1) algorithms for extracting multi-word phrase frequencies and phrase proximities (physical closeness of the multi-word technical phrases) from any type of large textual database, to augment (2) interpretative capabilities of the expert human analyst. DT was used to obtain technical intelligence from a Fractals database derived from the Science Citation Index/Social Science Citation Index (SCI). Phrase frequency analysis by the technical domain experts provided the pervasive technical themes of the Fractals database, and the phrase proximity analysis provided the relationships among the pervasive technical themes. Bibliometric analysis of the Fractals literature supplemented the DT results with author/journal/institution publication and citation data.
ZIPF ANALYSIS OF AUDIO SIGNALS
Authors: DELLANDRÉA E. , MAKRIS P. , VINCENT N.
Published: March 2004

This paper deals with several of the possible uses of Zipf and inverse Zipf laws in the field of audio signal analysis. We show that these laws are powerful analysis tools allowing the extraction of information not available by standard methods. The adaptation of Zipf and inverse Zipf laws to audio signals requires a coding of these signals into text-like data, considered as sequences of patterns. Because these codings are of first importance since they have to bring to the fore relevant information within signals, three types of codings have been developed, depending on the representation of the audio signal it is based on: temporal, frequential and time-scale representations. Once audio signal has been coded, features linked to Zipf and inverse Zipf approaches are computed. Finally, the classification step aims at the identification of signals. Four classification methods have been considered as well as a fusion method that combines these classifiers. In order to evaluate our method, we apply it on medical acoustical signals. They occur when swallowing and contain xiphoidal sounds. The problem is to extract and characterize xiphoidal sounds according to the gastro-oesophageal reflux pathological state. The aim is to help medical doctors to characterize and diagnose this pathology, and to give, in the end, a decision help tool as efficient as possible.
FRACTAL DIMENSIONS FOR UNSATURATED POROUS MEDIA
Authors: YU BOMING , LI JIANHUA
Published: March 2004

The analytical expressions of the fractal dimensions for wetting and non-wetting phases for unsaturated porous media are derived and are found to be a function of porosity, maximum and minimum pore sizes as well as saturation. There is no empirical constant in the proposed fractal dimensions. It is also found that the fractal dimensions increase with porosity of a medium and are meaningful only in a certain range of saturation Sw, i.e. Sw>S min for wetting phase and Sw<S max for non-wetting phase at a given porosity, based on real porous media for requirements from both fractal theory and experimental observations. The present analysis of the fractal dimensions is verified to be consistent with the existing experimental observations and it makes possible to analyze the transport properties such as permeability, thermal dispersion in unsaturated porous media by fractal theory and technique.
VISUALIZATION OF DATA ON BASIS OF FRACTAL GROWTH
Authors: VAN LOOCKE PHILIP
Published: March 2004

An algorithm for the visualization of n-dimensional binary spaces is considered. The algorithm is put in metric terms, and reformulated in terms of branching structures. The difference between metric and structural visualizations is discussed. Then, a hybrid method is proposed. Tree structures are grown in accordance with a metric error function. The method is illustrated with an example in the context of microbial taxonomy, and compared with a Kohonen map.
STUDY ON THE ALLOCATION OF R&D INVESTMENT: METHOD OF EVALUATING AND SELECTING R&D PROJECTS FOR INVESTMENT
Authors: NAKAMURA YOSHIKI , TSUJI MASASHIGE
Published: March 2004

Any enterprise must undertake evaluation processes in order to select the best R&D projects to help expand their business opportunities, and then make R&D investment decisions. This study presents an evaluation tool for such projects. An assessment of various types of project proposals is conducted, based on a number of assumptions. First, to what extent are these intended projects connected with the business or technology strategy of the enterprise in question? Second, how can these projects contribute to both the business and future growth prospects of the firm? Finally, will the company be able to complete the projects with its current manpower and technology? To confirm the validity of the methods used by the proposed assessment tools, this paper gives several concrete examples, complete with numeric figures. The data have been made available through a kind cooperation with one of the leading automobile companies in Japan.