bluuebunny/crossref_metadata_2025 huggingface dataset:
Volumetric contraction in some tooth‐coloured restorative materials
Authors: Bryant RW , Mahler DB
Published: March 2008

Background
: Much of the concern about the setting contraction of tooth‐coloured restorative materials has been focused on the composite resins. This study investigated setting contraction of a range of glass‐ionomer materials and included, for comparison, products from other groups of restorative materials.

Methods
: A deflecting disk method was used to determine the volumetric contraction of three conventional (non‐light cured) glass‐ionomer cements (GICs), two restorative, one “lining” consistency and one adhesive/lining consistency resin‐modified glass‐ionomers (RMGIs), two resin adhesives, three restorative composite resins and two compomers. The influence of powder:liquid ratio on two hand‐mixed materials was also examined.

Results
: The light‐cured materials (including RMGIs) showed substantially greater per cent contraction at 5 minutes than did the three conventional GICs (not light cured) and a substantially greater proportion of the 30‐minute contraction had occurred at 5 minutes for these light‐cured materials. Their further contraction after 1 hour was generally less than 5 per cent of the 1 hour contraction.

Conclusion
: Although the conventional GICs contract more slowly in the first 5 minutes, by 30 minutes the current restorative GICs and RMGIs exhibit a volumetric setting contraction that is comparable with the composite resins and compomers and is generally in the range of 2–3 per cent.
Antimicrobial action of calcium hydroxide, chlorhexidine and their combination on endodontic pathogens
Authors: Ballal V. , Kundabala M. , Acharya S. , Ballal M.
Published: March 2008

Background
: The common recovery of Candida albicans and Enterococcus faecalis from failed root canals of teeth in which previous treatment has failed is notable. These organisms have been shown to be resistant to antimicrobial action of calcium hydroxide but are sensitive to chlorhexidine gluconate. The aim of the present in vitro study was to investigate the antimicrobial efficacy of calcium hydroxide paste, 2% chlorhexidine gel and their combination against Candida albicans and Enterococcus faecalis.

Methods
: Inoculae of these organisms were used to make lawn cultures on Sabouraud's dextrose agar and blood agar plates. Wells were prepared with these lawn cultures and filled with calcium hydroxide paste, 2% chlorhexidine gel and their combination. The agar plates were kept overnight for incubation at 37°C and the zone of inhibition was examined after 24 and 72 hours.

Results
: The results suggest that 2% chlorhexidine gel alone is more effective at 72 hours than calcium hydroxide paste alone or in combination with 2% chlorhexidine gel against both the organisms, even though calcium hydroxide showed better antifungal efficacy against Candida albicans at 24 hours.

Conclusion
: In failed root canal treatments, 2% chlorhexidine gel may be a more effective intracanal medicament than calcium hydroxide paste or their combination against Candida albicans and Enterococcus faecalis.
Caries experience among 45–54 year olds in Adelaide, South Australia
Authors: Brennan DS , Spencer AJ , Roberts‐Thomson KF
Published: March 2008

Background
: Middle‐aged adults are an important focus of dental policy with increasing retention of teeth and use of dental services. The aims of the study were to describe the caries experience of 45–54 year olds by dental visit pattern, dental behaviour, socio‐demographics and socio‐economic status.

Methods
: A random sample of 45–54 year olds from Adelaide, South Australia was surveyed by self‐complete questionnaire during 2004–2005 with up to four follow‐up mailings to non‐respondents (n = 879, response rate = 43.8 per cent). Oral examinations were performed by calibrated dentists on 709 persons (completion rate = 80.7 per cent).

Results
: The mean number (95% CI) of decayed teeth was 0.39 (0.31–0.47), with 5.25 (4.92–5.58) missing teeth, 11.0 (10.62–11.32) filled teeth, and DMFT was 16.61 (16.21–17.01). Multivariate regressions of caries experience by dental visit pattern, dental behaviour, socio‐demographics and socio‐economic status found: time since last visit of less than 12 months was related (P < 0.05) to fewer decayed teeth (β= ‐0.40), more filled teeth (β= 1.55) and a higher DMFT (β= 1.24); a last visit for relief of pain was related to more decayed teeth (β= 0.56); tooth brushing 8+ times per week was related to fewer decayed (β= ‐0.36), and missing teeth (β= ‐1.13), and lower DMFT (β= ‐1.58); not cleaning between teeth was related to more missing teeth (β= 0.94); males had fewer missing teeth (β= ‐0.76); having a diploma/degree was related to fewer missing teeth (β= ‐1.07) and lower DMFT (β= ‐1.27); card holder status was related to more missing teeth (β= 1.26); and household income of $80 000+ was related to fewer missing teeth (β= ‐0.96) and a lower DMFT (β= ‐1.35).

Conclusions
: Dental visit pattern, dental behaviour, socio‐demographics and socio‐economic status were all related to caries experience. Overall DMFT was lower for those who brushed more frequently, had higher levels of education and higher household income.
Contemporary Class II orthodontic and orthopaedic treatment: a review
Authors: Tadic N. , Woods M.
Published: March 2008

The literature regarding the dental and facial soft tissue effects of various forms of contemporary Class II orthodontic and orthopaedic treatment is reviewed. Treatment outlined includes the use of headgear and functional appliances to attempt to modify the facial growth process and the extractions of premolar teeth as part of overall fixed appliance treatment. The conclusions of numerous articles highlight the fact that many approaches to treatment can be successful in correcting Class II malocclusions. Findings reported in recent literature also now show that the extractions of premolar teeth, for instance, as part of Class II treatment, do not necessarily lead to direct soft tissue effects. If lip profile changes do occur, it seems that they are far more likely to be positive aesthetically, than negative.
The survival of vital and non‐vital deciduous molar teeth following pulpotomy
Authors: Hill MW
Published: March 2008

Background: There is scant evidence supporting the criteria for establishing the suitability of a deciduous molar for a pulpotomy. Although some criteria, such as patient age, are logical the importance of other factors on tooth survival has not been established.

Methods: All pulpotomies performed at 20 school dental clinics over a period of 15 months were reported together with date of birth, gender, tooth treated, presenting signs and symptoms, pulp status and date and method of treatment. Operators performed the treatment according to their usual procedures. Data were analysed statistically using Statview 5.0 (SAS Institute).

Results: The outcome of pulpotomy of 465 deciduous teeth in 403 patients was evaluated. The mean age of the patients was 7.4 ± 0.1 years. Two hundred and seventy‐two teeth were vital and 193 were non‐vital. One hundred and ninety‐six teeth were treated with the one‐step formocresol method and 269 with the two‐step formocresol method. The age and gender of the patients did not differ between the vital and non‐vital groups. There was no influence of mode of treatment on the asymptomatic survival of the teeth in the mouth. The median survival times were significantly longer in vital (32.7 ± 1.4 months) than non‐vital teeth (20.4 ± 3.0 months; p < 0.0001). The only factors significantly influencing the survival of pulpotomized teeth were the age of the patient (p < 0.0001), the non‐vitality of the pulp (p < 0.0001) and the presence of a radiolucency (p=0.031).

Conclusion: Both vital and non‐vital teeth were able to survive for extended periods following pulpotomy but the presence of an associated radiolucency or a non‐vital pulp at the time of treatment is negatively associated with time of survival.
Incidence and progression of approximal carious lesions among school children in Western Australia
Authors: Arrow P.
Published: March 2008

Background: An understanding of carious lesion behaviour is important in timing and frequency of radiographic examinations. The aim of this study was to examine the occurrence and behaviour of approximal enamel lesions in permanent teeth among children in Western Australia and test the effect of easily measured factors on the rate of lesion progression.

Methods: Bitewing radiographs of children enrolled with the School Dental Service in Western Australia were scored for the occurrence and progression of enamel caries using established criteria. Time to lesion occurrence was estimated by the use of the Kaplan‐Meier analysis, bivariate tests of survival functions were undertaken using the log rank test and the influence of the measured factors were tested using the multivariate Cox proportional hazard model.

Results: The median time to occurrence of enamel caries was 6.1 months; median time to dentine caries was 77.7 months. Multivariate analysis shows gender (hazard ratio, male 0.65), baseline permanent tooth caries experience (hazard ratio 1.15) and time at risk since eruption (hazard ratio 0.88) were important factors in the initiation of enamel caries while time since eruption (hazard ratio 0.87), clinician's rating of risk (hazard ratio, moderate risk 2.78, high risk 5.00) and residence in fluoridated area (hazard ratio, fluoridate 0.44) were all statistically significant for enamel caries progression.

Conclusions: Time to occurrence of enamel lesions in approximal surfaces is relatively rapid while progression into dentine is relatively slow. Clinicians were able to assign the risk of lesion progression in a child. Residence in a fluoridated area has a marked retarding effect on enamel lesion progression but not on initiation of enamel lesions. These factors may be useful in developing a schedule for timing and frequency of radiographic examinations among children in Western Australia.
Aesthetic management of severely fluorosed incisors in an adolescent female
Authors: Ng F. , Manton DJ
Published: March 2008

Background: Dental fluorosis is a condition of enamel hypomineralization due to the effects of excessive fluoride on ameloblasts during enamel formation. Delayed degradation of enamel matrix proteins or inhibited protein removal results in impaired and incomplete crystal growth, producing hypomineralized and porous enamel. Severely fluorosed teeth may undergo post‐eruptive surface breakdown and post‐eruptive dark brown to black staining.

Methods: A 13 year old girl presented with severely discoloured maxillary central incisors. Initial aesthetic management of these teeth was conservative, including in‐office tooth whitening, microabrasion and take‐home whitening.

Results: Dark brown to black staining of the teeth was reduced successfully without the need for gross mechanical preparation of the enamel. Further improvement of aesthetics was achieved with composite veneers.

Conclusions: Conservative treatment options such as tooth whitening and microabrasion can dramatically improve severely discoloured fluorosed teeth. This can provide a satisfactory interim outcome or minimize the removal of discoloured enamel and dentine prior to the provision of composite veneers. The use of casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP™) may enhance remineralization and decrease postoperative sensitivity following tooth whitening and microabrasion procedures in hypomineralized teeth.
Geographic location and indirect costs as a barrier to dental treatment: a patient perspective
Authors: Curtis B. , Evans RW , Sbaraini A. , Schwarz E.
Published: March 2008

Background: The recently published National Survey of Adult Oral Health 2004–06 indicated that tooth loss, mean decayed and number of DMF teeth were all higher outside capital city locations. In addition, dental attendance patterns were worse in terms of frequency, reason for visit, and continuity in rural and remote locations, but there was no difference by geographical location in terms of financial barriers to dental care. The objective of this research was to identify, quantify and analyse some of the non‐treatment costs associated with dental treatment from the perspective of the patient and to determine whether the perceived impact of those costs may limit access to dental care.

Methods: This cohort study was nested within a clinical trial. Patients had been allocated to treatment arms within clusters dependent on the randomization status of the dental practice they usually attended, classified as major city, regional or remote. A questionnaire was developed from a series of focus groups in which patients were asked to identify the domains of non‐treatment costs associated with a dental visit that were important to them and to quantify those costs. Factor analysis was used to reduce these items to four core scales. These scales were assessed for reliability and validity. Regression and ANCOVA was used to explore differences in DMFS scores between the three groups and a predictive model developed to adjust for potential confounders.

Results: Two core scales were identified as key drivers on the perceived impact of indirect costs associated with dental visits; travel impact and family impact. Patients living in remote locations incurred significantly higher indirect costs associated with dental treatment and higher mean DMFS scores.

Conclusions: Patient perception of the impact of travel costs and impact on family life are major drivers restricting access to dental services for people living in remote locations in New South Wales. Further research using outcomes directly related to access is required to validate the claim that patients living in regional and remote locations suffer both perceived and real financial barriers to dental care.
Effect of remineralization/demineralization cycles on mineral profiles of Fuji IX Fast in vitro using electron probe microanalysis
Authors: Ab‐Ghani Z. , Ngo H. , McIntyre J.
Published: March 2008

Background: There have been concerns about the dissolution of conventional glass ionomer cement (GIC) and its possible degradation when exposed to an acidic environment over time. The objective of this study was to investigate the effects of exposure of Fuji IX Fast to the simulated acidic aspects of the oral environment in terms of any changes in the elemental composition of strontium (Sr), phosphorus (P), calcium (Ca) and fluorine (F) which resulted at the surface of this material.

Methods: Sixty‐five cylindrical blocks of Fuji IX Fast were prepared using split moulds. The demineralizing solution was an acetate buffered demineralizing solution at pH 4.3. The remineralizing solution was a buffered solution containing 1.5 mM Ca, 0.9 mM P and 10 ppm F at pH 7. The blocks of Fuji IX Fast were subjected either to two‐day alternating cycles of remineralization and demineralization for up to 24 days (test); 6 two‐day cycles of demineralizing or remineralizing solution separately, or deionized distilled water alone (controls) or were left untreated (base line control). Mineral profiles of Ca, P, Sr and F within 100 μm of the material surface were assessed following 8, 16 and 24 days of treatment (test); 4, 8 or 12 days (controls) or for baseline control samples, using electron probe microanalysis (EPMA).

Results: There were significant changes in mineral profile in the test specimens in terms of Sr and Ca concentrations. A molecule for molecule exchange of these elements resulted between GIC and eluant solutions. Fluoride loss from the GIC occurred to the level comparable with uptake levels recorded in eluant solutions from previous studies. The ionic exchanges appeared to be the result of dissolution followed by an equilibrium‐driven diffusion. These exchanges were superficial though substantial.

Conclusions: Simulated exposure of Fuji IX to the oral environment resulted in an exchange of Ca from the bathing solutions into Fuji IX to replace any Sr which was lost to the GIC. Fluorine loss from the GIC followed previously described patterns. The possible clinical significance of this exchange was discussed.
Effects of pulsed electromagnetic field vibration on tooth movement induced by magnetic and mechanical forces: a preliminary study
Authors: Darendeliler M Ali , Zea A. , Shen G. , Zoellner H.
Published: March 2008

Background: This study was designed to determine whether or not high‐frequency and low‐magnitude vibration affects orthodontic tooth movement caused by magnetic or/and mechanical forces.

Methods: Forty‐four 7‐week‐old Wistar rats were randomly divided into four groups, with each group further divided into experimental and control subgroups. Neodymium‐Iron‐Boron (Nd‐Fe‐B) magnets and Sentalloy closed coil springs were placed between maxillary or mandibular first molars and incisors to activate tooth movement. The animals of experimental subgroups were exposed to the vibration induced by pulsed electromagnetic fields (PEMF) whilst the control subgroups were under normal atmosphere. The experiment lasted for 14 days and all of the animals were sacrificed for examination. The changes in the space between the molar and incisor were measured to indicate the amount of tooth movement.

Results: The coil springs, either with sham or active magnets, move molar much more than magnets alone, regardless of absence or presence of PEMF (p < 0.001). Under PEMF, the coil spring moved significantly more amount of tooth movement than that of coil‐magnet combination (p < 0.01), as did the magnets compared to sham magnets (p < 0.019). Under a non‐PEMF scenario, there was no significant difference in tooth movement between coil spring and coil‐magnets combination, nor was there difference between magnets and sham magnets.

Conclusions: It is suggested that the PEMF‐induced vibration may enhance the effect of mechanical and magnetic forces on tooth movement.
Dental caries experience in Aboriginal and Torres Strait Islanders in the Northern Peninsula Area, Queensland
Authors: Hopcraft M. , Chow W.
Published: March 2008

Background: A survey of dental caries experience in children was undertaken in five Aboriginal and Torres Strait Islander communities in the Northern Peninsula Area of Queensland prior to the introduction of water fluoridation.

Methods: Data were obtained from screening dental examinations conducted by the Australian Army as part of a community assistance programme between May and September 2004 from 486 children aged 4–15 years. The clinical examinations were performed in a dental van using a dental chair, light, mirror and probe by a single calibrated examiner.

Results: Caries experience was high with a mean 6‐year‐old dmft of 6.37 and a mean 12‐year‐old DMFT of 3.50. The 6‐year‐old dmft Significant Caries Index (SiC) for the third of the population with the highest caries experience was 11.65 and the 12‐year‐old DMFT SiC was 7.08. Only 15.3 per cent of 6‐year‐old children had dmft=0 and 28.9 per cent of 12‐year‐old children had DMFT=0.

Conclusions: Dental caries was a significant problem for these remote communities. Aboriginal and Torres Strait Islander children from the Northern Peninsula Area of Queensland had more than four times the caries experience of Australian children for both 6‐year‐old dmft and 12‐year‐old DMFT.
Implant or the natural tooth—a contemporary treatment planning dilemma?
Authors: John V. , Chen S. , Parashos P.
Published: March 2008

An assessment of whether to rehabilitate a tooth requiring endodontic treatment or to replace it with a dental implant can often involve a challenging and complex decision‐making process. This paper reviews the literature pertaining to both treatment modalities and identifies key issues that need careful consideration in planning the most appropriate course of care in a given clinical situation. A need to appreciate advances across both disciplines is highlighted, allowing the development of effective interdisciplinary evidence‐based treatment strategies to maximize treatment outcome.
Treatment planning the endodontic case
Authors: Yeng T. , Messer HH , Parashos P.
Published: March 2008

Following a definitive diagnosis of the need for root canal treatment, the treatment planning stage should be straightforward if a logical sequence of decision‐making is followed. Very few contra‐indications exist for providing root canal treatment, but the planning must include several aspects. Firstly, is root canal treatment best for the patient to maintain a functional dentition long term? Secondly, who should provide the treatment? Thirdly, what are the restorative options that will ensure the best long‐term prognosis? The sequencing of root canal treatment generally occurs early in a typical treatment plan, and prompt restoration after treatment is crucial to long‐term survival of the tooth.
An Assessment of the Influence of Environmental Factors on Cavitation Instabilities
Authors: Kawakami Damien T. , Fuji A. , Tsujimoto Y. , Arndt R. E. A.
Published: March 2008

Cavitation induced flow instabilities are of interest in numerous applications. Experimental and numerical investigations of this phenomenon are taking place at several institutions around the world. Although there is qualitative agreement among the numerous recent papers on the subject, there is a lack of agreement with regard to important details, such as the spectral content of unsteady lift oscillations. This paper summarizes observations of a cavitating NACA0015 foil in three different tunnels that revealed remarkably different cavity shedding appearances and behaviors. Some of the differences were attributed to system instabilities. However, in addition to a different cavitation behavior attributed to system instabilities, it was found that differences in gas content could significantly alter the lift spectrum of a cavitating foil. For a certain range of the composite parameter σ∕2α near 4, the dominant frequency appears to double when the gas content is reduced by a half. It is also argued that surface effects can have a significant influence on fully wetted time during cavity shedding. Normally, surface effects are assumed to play an important role in the initial inception of a fully wetted hydrofoil with gas content being the primary factor governing developed cavitation behavior. However, the repetitive nature of the process implies that each shedding cycle is an individual inception process. Hence, the unexpected role of surface effects in partially cavitating hydrofoils. The conclusions reached have important ramifications concerning numerical code verification that is a topic of major concern.
Experimental study on swelling characteristics of compacted bentonite
Authors: Komine Hideo , Ogata Nobuhide
Published: March 2008

Compacted bentonites are attracting greater attention as back-filling (buffer) materials for repositories of high-level nuclear waste. However, since there are few studies about the swelling characteristics of compacted bentonites, it is first necessary to clarify the fundamental swelling characteristics in detail. For this purpose, various laboratory tests on the swelling deformation and swelling pressure of compacted bentonites were performed and the results analyzed. The following conclusions were drawn from the study. (i) The curve of swelling deformation versus time is strongly dependent on the initial dry density, vertical pressure, and initial water content. The maximum swelling deformation, however, is almost independent of initial water content, and the maximum swelling deformation increases in proportion to the initial dry density, (ii) The maximum swelling pressure increases exponentially with increasing initial dry density, whereas the maximum swelling pressure is almost independent of initial water content. (iii) The swelling mechanism of compacted bentonite was considered on the basis of the swelling behavior of swelling clay particles such as montmorillonite. Furthermore, a model of the swelling characteristics and a new parameter (swelling volumetric strain of montmorillonite), which were able to evaluate the swelling characteristics of compacted bentonite, were proposed. Key words : bentonite, laboratory test, nuclear waste disposal, swelling deformation, swelling pressure.
Equations for the soil-water characteristic curve
Authors: Fredlund D.G. , Xing Anqing
Published: March 2008

The soil-water characteristic curve can be used to estimate various parameters used to describe unsaturated soil behaviour. A general equation for the soil-water characteristic curve is proposed. A nonlinear, least-squares computer program is used to determine the best-fit parameters for experimental data presented in the literature. The equation is based on the assumption that the shape of the soil-water characteristic curve is dependent upon the pore-size distribution of the soil (i.e., the desaturation is a function of the pore-size distribution). The equation has the form of an integrated frequency distribution curve. The equation provides a good fit for sand, silt, and clay soils over the entire suction range from 0 to 106 kPa. Key words : soil-water characteristic curve, pore-size distribution, nonlinear curve fitting, soil suction, water content.
Repeated-load response of aggregates in relation to track quality index
Authors: Raymond Gerald P. , Bathurst Richard J.
Published: March 2008

Track quality rating systems are briefly introduced as a background for undertaking a study of the repeated-load response of ballast aggregates. The results from a number of different laboratory investigations are reviewed and this data interpreted in terms of track quality behaviour. The paper reviews selected results from repeated-load triaxial tests used to investigate the repeated-loading response of different granular railway ballasts at stress levels comparable with those below North America heavy freight axle loads. These results are used to establish an aggregate index to predict deformation and breakdown of ballast under repeated loading. Large-scale test programs are reviewed that relate aggregate quality to simulated ballasted track formation response using a 0.9 m long by 250 mm wide tie to represent a typical loaded rail seat. The large-scale testing was restricted to one aggregate that was subjected to a range of load levels and artificial subgrade stiffness. Similar related work on coarse, single-sized aggregates recommended for drainage layers in highway pavements is reviewed to illustrate the trade-offs between support compressibility and quality of aggregate defined by the aggregate index value. The laboratory tests and model performance are compared with published data to establish a laboratory performance rating in the form of an aggregate index for prediction of those track quality indices that relate to deformation as a function of aggregate type. Key words : ballast, aggregate, hardness, toughness, railway, track quality.
Filtration behaviour of nonwoven geotextiles
Authors: Fannin R.J. , Vaid Y.P. , Shi Y.C.
Published: March 2008

Criteria for soil retention and permeability are important in the proper selection of a geotextile in filtration design. Gradient-ratio tests have been performed to assess the compatibility of nonwoven geotextiles with soils exhibiting a range of gradations. Observations of any soil piping through a geotextile were used to evaluate soil-retention criteria. The American Society for Testing and Materials test apparatus includes additional ports that were used to define a modified gradient ratio, which is a better indicator of flow condition. Measurements of the distribution of water head through the soil sample and geotextile specimen, and its variation with imposed hydraulic gradient and time, are used to establish the permeability of the soil and soil–geotextile composite. The composite layer is relatively thin. A unified interpretation of the results is presented that shows a gradient ratio greater than one means the permeability of the composite is less than that of the protected soil: the condition is acceptable if it can be demonstrated that no impediment of seepage flow will result. Key words : filtration, geotextile, soil retention, gradient ratio, permeability.
Bearing capacity of flexible batter piles under eccentric and inclined, loads in layered soil
Authors: Meyerhof G.G. , Yalcin A.S.
Published: March 2008

The behaviour of single free-head model flexible vertical and batter piles under the general case of eccentric and inclined loads in two-layered soil is investigated. The bearing capacity of the piles is found to depend on the layered structure, the eccentricity and inclination of the load, and the pile batter. The theoretical estimates of ultimate loads obtained from semiempirical relations agree fairly well with the test results. Key words : bearing capacity, deformation, batter pile, eccentricity factor, eccentric load, inclination factor, inclined load, layered soil, model test, sand, clay.
Prediction for swelling characteristics of compacted bentonite
Authors: Komine Hideo , Ogata Nobuhide
Published: March 2008

Compacted bentonites are attracting greater attention as back-filling (buffer) materials for high-level nuclear waste repositories. For this purpose, it is very important to quantitatively evaluate the swelling characteristics of compacted bentonite. New equations for evaluating the relationship between the swelling deformation of compacted bentonite and the distance between two montmorillonite layers are derived. New equations for evaluating the ion concentration of pore water and the specific surface of bentonite, which significantly influence the swelling characteristics of compacted bentonite, are proposed. Furthermore, a prediction method for the swelling characteristics of compacted bentonite is presented by combining the new equations with the well-known theorectical equations of repulsive and attractive forces between two montmorillonite layers. The applicability of this method was investigated by comparing the predicted results with laboratory test results on the swelling deformation and swelling pressure of compacted bentonites.

Key words: bentonite, diffuse double-layer theory, van der Waals force, nuclear wastes disposal, swelling deformation, swelling pressure.
Use of the piezocone test to predict the axial capacity of driven and jacked piles in clay
Authors: Almeida Marcio SS , Danziger Fernando AB , Lunne Tom
Published: March 2008

Results of 43 load tests on driven and jacked piles performed at eight calyey sites have been back-analysed using piezocone test data. A method to evaluate the axial capacity of piles has been proposed in which the pile unit skin friction and the unit end bearing resistance are computed from the net corrected cone resistance, qnet. Correlation factors between piezocone and pile load tests were back-calculated using this approach. As most of the pile tests performed were tension tests, special emphasis was given to the evaluation of the pile unit skin friction.

Key words: clay, pile, piezocone, cone penetration test, axial pile capacity, skin friction.
On the prediction of hydraulic conductivity of frozen soils
Authors: Tarnawski Vlodek R , Wagner Bernhard
Published: March 2008

This paper describes a mathematical model for predicting the hydraulic conductivity of partially frozen soils on the basis of limited input data such as grain size distribution and bulk density or porosity. A new model is based on an analogy for the hydraulic conductivity of frozen and unfrozen soils and models for the estimation of hydraulic properties of soils and unfrozen water content. Campbell's model was used for prediction of soil-water characteristics from limited data, while unfrozen water content was obtained from two models (by P.J. Williams and D.M. Anderson) applied to two different temperature ranges. The new model can be used for the rapid estimation of the hydraulic conductivity of practically any freezing soil having log-normal grain size distribution and for computer simulation of moisture migration in soils below the freezing point. An acceptable conformity between the model prediction and measured data for pure sand has been achieved. The computer program developed requires the following input data: grain size distribution, bulk density or porosity, and soil temperature.

Key words: frozen soils, hydraulic conductivity, bulk density, grain size distribution, unfrozen water content.
Soil restraint against oblique motion of pipelines in sand
Authors: Hsu Tung-Wen
Published: March 2008

The soil restraint on pipelines due to oblique relative movement betwen the pipeline and dry loose sand was investigated. Model pipes 1.22 m long with diameters of 38.1, 76.2, 152.4, and 228.6 mm are obliquely moved from vertical to horizontal direction in the drag box to study the soil restraint of the oblique pipes with various relative velocities. All test results indicate that the dimensionless ultimate soil restraints have a power law relationship with the pipe velocity. The velocity exponent increases slightly with the oblique angle and embedded depth of the pipe. Furthermore, the soil restraint also increases with both the pipes oblique angle and embedded depth. Most of the increase in the soil restraint is associated with the oblique angles in the interval between 45 and 90°. The limit equilibrium model succesfully predicted the soil restraint of the pipe. Normailized forcedisplacement relationships of soilpipe interaction could be represented by two-constant hyperbolic equation. The findings show that the first constant value, a, increases, whereas the second value, b, decreases with the oblique angle, respectively.

Key words: pipelines, soil restraint, oblique motion, sand.
SEMILEPTONIC $\Lambda_b\to\Lambda\nu\bar\nu$ DECAY IN THE LEPTOPHOBIC Z′ MODEL
Authors: ŞIRVANLI B. B.
Published: March 2008

We study the exclusive flavor changing neutral current process [Formula: see text] in the leptophobic Z′ model, where charged leptons do not couple to the extra Z′ boson. The branching ratio, as well as, the longitudinal, transversal and normal polarizations are calculated. It has been shown that all these physical observables are very sensitive to the existence of new physics beyond the standard model and their experimental measurements can give valuable information about it.
METHOD ON HOLOMORPHIC VECTOR FUNCTIONS AND APPLICATIONS IN TWO-DIMENSIONAL QUASICRYSTALS
Authors: GAO YANG , XU BAI-XIANG
Published: March 2008

Generalization of the Stroh formalism to two-dimensional quasicrystal materials results in a ten-dimensional formalism for which there are five pairs of complex eigenvalues. By virtue of the generalized Stroh formalism, two-dimensional problems of quasicrystals elasticity are transferred into the boundary value problems of holomorphic vector functions in a given region. If the conformal mapping from an ellipse to a circle is known, a general method can be presented for solving the boundary value problems of holomorphic vector functions. Using the necessary and sufficient condition of boundary value problems of holomorphic vector functions, several basic two-dimensional problems in two-dimensional quasicrystals are solved.
ELECTRONIC TRANSPORT IN ANISOTROPIC DISORDERED QUANTUM WIRE
Authors: KAYA TUNCER
Published: March 2008

We have investigated the transport properties of anisotropic disordered quantum wire by the method of energy level statistics and transfer matrix method. We have found a general average conductance relation in terms of the anisotropy parameter t, disorder strength W, and the cross-sectional area, A, of the wire. From the available numerical data, we have also shown that the anisotropic correlation length ξtcan be related to the isotropic correlation length ξ as ξt≃ t2ξ, for L ≃ A and ξt≃ tξ, for L ≫ A. Here, L is the length of the wire. In addition, anisotropic dependence of conductance fluctuation and conductance distribution have been studied to a certain extent.
DYNAMICS AND NONCLASSICAL PHOTON STATISTICS IN THE INTERACTION OF TWO-LEVEL SPIN SYSTEMS WITH A TWO-MODE CAVITY FIELD: A GENERALIZED JAYNES-CUMMINGS MODEL
Authors: GRINBERG HORACIO
Published: March 2008

The interaction of a two-level XYn-spin system with a two-mode cavity field is investigated through a generalized Jaynes-Cummings model in the rotating wave approximation. The spontaneous decay of a spin level was treated by considering the interaction of the two-level spin system with the modes of the universe in the vacuum state. The different cases of interest, characterized in terms of a detuning parameter for each mode, which emerge from the nonvanishing of certain commutation relations between interaction picture Hamiltonians associated with each mode, were analytically implemented and numerically discussed for various values of the initial mean photon number and spin-photon coupling constants. Photon distribution, time evolution of the spin population inversion, as well as the statistical properties of the field leading to the possible production of nonclassical states, such as antibunched light and violations of the Cauchy-Schwartz inequality are examined for an excited initial state. It was assumed that the two modes are initially in coherent states and have the same photon distribution. The case of zero detuning of both modes was treated in terms of a linearization of the expansion of the time evolution operator, while in other three cases, the computations were conducted via second- and third-order Dyson perturbation expansion of the time evolution operator matrix elements for the excited and ground states respectively.
EPR AND MAGNETIC SUSCEPTIBILITY STUDIES OF Gd3+ IONS-DOPED BISMUTH–GERMANATE GLASS MATRIX
Authors: PASCUTA P. , BOSCA M. , CULEA M. , SIMON S. , CULEA E.
Published: March 2008

Glasses of the x Gd 2 O 3 · (100-x)[4 Bi 2 O 3 · GeO 2] system, with 1 ≤ x ≤ 30 mol% were obtained and investigated by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The EPR spectra of the studied glasses reveal resonance sites with an unexpected high crystalline field in addition to the "U" spectrum, typical for Gd 3+ ions in glasses. This absorption line is due to Gd 3+ ions that replace Bi 3+ ions from the host glass matrix and can play former role of the unconventional network in the studied glasses. EPR and magnetic susceptibility data show that for low Gd 2 O 3 content, x ≤ 10 mol%, the Gd 3+ ions are randomly distributed in the host glass matrix and are present only as isolated species. For higher Gd 2 O 3 content, x > 10 mol%, the Gd 3+ ions appear as both isolated and antiferromagnetically coupled species.
WAVELESS APPROXIMATION THEORIES OF GRAVITY
Authors: ISENBERG JAMES A.
Published: March 2008

The analysis of a general multibody physical system governed by Einstein's equations is quite difficult, even if numerical methods (on a computer) are used. Some of the difficulties — many coupled degrees of freedom, dynamic instability — are associated with the presence of gravitational waves. We have developed a number of "waveless approximation theories" (WAT's) which repress the gravitational radiation and thereby simplify the analysis. The matter, according to these theories, evolves dynamically. The gravitational field, however, is determined at each time step by a set of elliptic equations with matter sources. There is reason to believe that for many physical systems, the WAT-generated system evolution is a very accurate approximation to that generated by the full Einstein theory.
Λ-CDM UNIVERSE: A PHENOMENOLOGICAL APPROACH WITH MANY POSSIBILITIES
Authors: MUKHOPADHYAY UTPAL , RAY SAIBAL , CHOUDHURY S. B. DUTTA
Published: March 2008

A time-dependent phenomenological model of Λ, viz. [Formula: see text], is selected to investigate the Λ-CDM cosmology. The time-dependent form of the equation-of-state parameter ω is derived and it has been possible to obtain the sought-for flip of sign of the deceleration parameter q. The present age of the Universe, calculated for some specific values of the parameters, agrees very well with the observational data.
INFORMATION FLOWS IN CAUSAL NETWORKS
Authors: AY NIHAT , POLANI DANIEL
Published: March 2008

We use a notion of causal independence based on intervention, which is a fundamental concept of the theory of causal networks, to define a measure for the strength of a causal effect. We call this measure "information flow" and compare it with known information flow measures such as transfer entropy.
A METHOD FOR INFERRING HIERARCHICAL DYNAMICS IN STOCHASTIC PROCESSES
Authors: GÖRNERUP OLOF , JACOBI MARTIN NILSSON
Published: March 2008

Complex systems may often be characterized by their hierarchical dynamics. In this paper we present a method and an operational algorithm that automatically infer this property in a broad range of systems — discrete stochastic processes. The main idea is to systematically explore the set of projections from the state space of a process to smaller state spaces, and to determine which of the projections impose Markovian dynamics on the coarser level. These projections, which we call Markov projections, then constitute the hierarchical dynamics of the system. The algorithm operates on time series or other statistics, so a priori knowledge of the intrinsic workings of a system is not required in order to determine its hierarchical dynamics. We illustrate the method by applying it to two simple processes — a finite state automaton and an iterated map.
Tracking Web spam with HTML style similarities
Authors: Urvoy Tanguy , Chauveau Emmanuel , Filoche Pascal , Lavergne Thomas
Published: March 2008

Automatically generated content is ubiquitous in the web: dynamic sites built using the three-tier paradigm are good examples (e.g., commercial sites, blogs and other sites edited using web authoring software), as well as less legitimate spamdexing attempts (e.g., link farms, faked directories).

Those pages built using the same generating method (template or script) share a common “look and feel” that is not easily detected by common text classification methods, but is more related to stylometry.

In this work we study and compare several HTML style similarity measures based on both textual and extra-textual features in HTML source code. We also propose a flexible algorithm to cluster a large collection of documents according to these measures. Since the proposed algorithm is based on locality sensitive hashing (LSH), we first review this technique.

We then describe how to use the HTML style similarity clusters to pinpoint dubious pages and enhance the quality of spam classifiers. We present an evaluation of our algorithm on the WEBSPAM-UK2006 dataset.
Adaptive quality of service management for enterprise services
Authors: Gmach Daniel , Krompass Stefan , Scholz Andreas , Wimmer Martin , Kemper Alfons
Published: March 2008

In the past, enterprise resource planning systems were designed as monolithic software systems running on centralized mainframes. Today, these systems are (re-)designed as a repository of enterprise services that are distributed throughout the available computing infrastructure. These service oriented architectures (SOAs) require advanced automatic and adaptive management concepts in order to achieve a high quality of service level in terms of, for example, availability, responsiveness, and throughput. The adaptive management has to allocate service instances to computing resources, adapt the resource allocation to unforeseen load fluctuations, and intelligently schedule individual requests to guarantee negotiated service level agreements (SLAs). Our AutoGlobe platform provides such a comprehensive adaptive service management comprising

—static service-to-server allocation based on automatically detected service utilization patterns,

—adaptive service management based on a fuzzy controller that remedies exceptional situations by automatically initiating, for example, service migration, service replication (scale-out), and

—adaptive scheduling of individual service requests that prioritizes requests depending on the current degree of service level conformance.

All three complementary control components are described in detail, and their effectiveness is analyzed by means of realistic business application scenarios.
A generic component model for building systems software
Authors: Coulson Geoff , Blair Gordon , Grace Paul , Taiani Francois , Joolia Ackbar , Lee Kevin , Ueyama Jo , Sivaharan Thirunavukkarasu
Published: March 2008

Component-based software structuring principles are now commonplace at the application level; but componentization is far less established when it comes to building low-level systems software. Although there have been pioneering efforts in applying componentization to systems-building, these efforts have tended to target specific application domains (e.g., embedded systems, operating systems, communications systems, programmable networking environments, or middleware platforms). They also tend to be targeted at specific deployment environments (e.g., standard personal computer (PC) environments, network processors, or microcontrollers). The disadvantage of this narrow targeting is that it fails to maximize the genericity and abstraction potential of the component approach. In this article, we argue for the benefits and feasibility of a generic yet tailorable approach to component-based systems-building that offers a uniform programming model that is applicable in a wide range of systems-oriented target domains and deployment environments. The component model, called
OpenCom
, is supported by a reflective runtime architecture that is itself built from components. After describing OpenCom and evaluating its performance and overhead characteristics, we present and evaluate two case studies of systems we have built using OpenCom technology, thus illustrating its benefits and its general applicability.
Incrementally parallelizing database transactions with thread-level speculation
Authors: Colohan Christopher B. , Ailamaki Anastassia , Steffan J. Gregory , Mowry Todd C.
Published: March 2008

With the advent of chip multiprocessors, exploiting intratransaction parallelism in database systems is an attractive way of improving transaction performance. However, exploiting intratransaction parallelism is difficult for two reasons: first, significant changes are required to avoid races or conflicts within the DBMS; and second, adding threads to transactions requires a high level of sophistication from transaction programmers. In this article we show how dividing a transaction into
speculative threads
solves both problems—it minimizes the changes required to the DBMS, and the details of parallelization are hidden from the transaction programmer. Our technique requires a limited number of small, localized changes to a subset of the low-level data structures in the DBMS. Through this method of incrementally parallelizing transactions, we can dramatically improve performance: on a simulated four-processor chip-multiprocessor, we improve the response time by 44--66% for three of the five TPC-C transactions, assuming the availability of idle processors.
State of the art in protocol research for underwater acoustic sensor networks
Authors: Akyildiz Ian F. , Pompili Dario , Melodia Tommaso
Published: March 2008

Underwater networks of sensors have the potential to enable unexplored applications and to enhance our ability to observe and predict the ocean. In this paper, architectures for two-dimensional and three-dimensional underwater sensor networks are proposed. A detailed overview on the current solutions for medium access control, network, and transport layer protocols is given and open research issues are discussed.
A survey of practical issues in underwater networks
Authors: Partan Jim , Kurose Jim , Levine Brian Neil
Published: March 2008

Underwater sensor networks are attracting increasing interest from researchers in terrestrial radio-based sensor networks. There are important physical, technological, and economic differences between terrestrial and underwater sensor networks. In this survey, we highlight a number of important practical issues that have not been emphasized in recent surveys of underwater networks, with an intended audience of researchers who are moving from radio-based terrestrial networks into underwater networks.