bluuebunny/crossref_metadata_2025 huggingface dataset:
The plaque inhibitory effect of a CPC mouthrinse in a 3‐day plaque accumulation model – a cross‐over study
Authors: Versteeg PA , Rosema NAM , Hoenderdos NL , Slot DE , Van der Weijden GA
Published: November 2009

To cite this article:
 
Int J Dent Hygiene 8, 2010; 269–275 DOI: 10.1111/j.1601‐5037.2009.00421.x Versteeg PA, Rosema NAM, Hoenderdos NL, Slot DE, Van der Weijden GA. The plaque inhibitory effect of a CPC mouthrinse in a 3‐day plaque accumulation model – a cross‐over study.

Abstract:  Objective:  To test the plaque inhibitory effect of an experimental 0.07% cetylpyridinium chloride (CPC) mouthrinse in a 3‐day plaque accumulation model in a cross‐over design.

Material and Methods:  A total of 30 subjects (non‐dental students), ≥18 years of age, were randomly assigned to use one of three different mouthrinses three times a day. After 3 days, the subjects returned for the clinical assessments and received a questionnaire to evaluate their attitude towards the product used by them. The cross‐over procedure was repeated twice to have all subjects use all products.

Results:  A total of 29 subjects completed the protocol and this resulted in a statistically significant difference between the three groups (P < 0.001) with regard to plaque scores. Over three sessions, the mean plaque scores were 2.17 for the control product, 1.14 for the CPC group and 1.12 for the 0.1% Hexetidine product (positive control). Results of the questionnaire show that, compared with hexetidine, the taste of the CPC was appreciated better, and less oral sensations were observed following rinsing.

Conclusion:  The CPC mouthrinse proved to be effective in inhibiting ‘de novo’ plaque formation to an extent similar to that of a 0.1% hexetidine product. Compared with hexetidine, the taste of the CPC was appreciated better and less oral sensations were observed following rinsing.
Long‐term effects of rapid weight gain in children, adolescents and young adults with appropriate birth weight for gestational age: the kiel obesity prevention study
Authors: Hitze B , Bosy‐Westphal A , Plachta‐Danielzik S , Bielfeldt F , Hermanussen M , Müller MJ
Published: November 2009

Aim:  This study investigates the effect of rapid weight gain in term children, adolescents and young adults born appropriate for gestational age.

Methods:  In all, 173 girls and 178 boys aged 6.1–19.9 (12.5 ± 3.1)years participated. Rapid weight gain (group 1) was defined as a change in weight‐SDS (standard deviation score) from birth till two years >0.67, ‘no change’ as ≥−0.67 and ≤0.67 (group 2) vs ‘slow weight gain’ as <−0.67 (group 3). BMI‐SDS, waist circumference (WC) z‐score, fat mass (FM)/fat free mass (FFM; Air‐Displacement‐Plethysmography), resting energy expenditure (REE; ventilated hood system), cardio‐metabolic risk factors, serum leptin and adiponectin were assessed. >90th age‐/sex‐specific BMI‐percentile was defined as overweight. Parental BMI, socio‐economic status and lifestyle were assessed as confounders.

Results:  A total of 22.8% gained weight rapidly, and 15.7% was overweight. Group 1 compared with group 2 and 3 subjects was taller, heavier and had a higher prevalence of overweight (girls/boys: 26.2%/28.9% vs 11.6%/19.0% vs 2.8%/5.0%; p < 0.01/p < 0.05). Concomitantly, a higher WC, %FM and FFM were observed. Rapid weight gain was positively associated with REE (adjusted for FFM) in boys (r = 0.26; p < 0.01), but not with cardio‐metabolic risk factors.

Conclusion:  Rapid weight gain was related to increases in height, weight, a higher prevalence of overweight and central fat distribution. In addition, rapid weight gain was related to a higher REE in boys, but not to cardio‐metabolic risk factors.
Land‐use legacies in a central Appalachian forest: differential response of trees and herbs to historic agricultural practices
Authors: Dyer James M.
Published: November 2009

Question: Are contemporary herb and tree patterns explained by historic land use practices? If so, are observed vegetation patterns associated with life‐history characteristics, soil properties, or other environmental variables?

Location: Southeastern Ohio, USA.

Methods: Using archival records, currently forested sites were identified with distinct land use histories: cultivated, pasture (but not plowed), and reference sites which appear to have never been cleared. Trees were recorded by size and species on twenty 20 m × 20 m plots; percent cover was estimated for each herb species in nested 10 m × 10 m plots. Environmental characteristics were noted, and soil samples analysed for nutrient availability and organic matter. Nonmetric multidimensional scaling ordination was performed separately on both tree and herb datasets to graphically characterize community composition among plots. Life‐history traits were investigated to explain observed compositional differences.

Results: Vegetation patterns were explained by current environmental gradients, especially by land‐use history. Cultivated and pasture sites had similar tree composition, distinct from reference sites. Herb composition of pasture and reference sites was similar and distinct from cultivated sites, suggesting the ‘tenacity’ of some forest herbs on formerly cleared sites. Tilling removes rhizomatous species, and disfavors species with unassisted dispersal. These life‐history traits were underrepresented on cultivated sites, although ant‐dispersed species were not.

Conclusions: Historic land‐use practices accounted for as much variation in species composition as environmental gradients. Furthermore, trees and herbs responded differently to past land‐use practices. Life‐history traits of individual species interact with the nature of disturbance to influence community composition.
Modulation of sterol homeostasis by the Cdc42p effectors Cla4p and Ste20p in the yeast Saccharomyces cerevisiae
Authors: Lin Meng , Grillitsch Karlheinz , Daum Günther , Just Ursula , Höfken Thomas
Published: November 2009

The conserved Rho‐type GTPase Cdc42p is a key regulator of signal transduction and polarity in eukaryotic cells. In the yeast Saccharomyces cerevisiae, Cdc42p promotes polarized growth through the p21‐activated kinases Ste20p and Cla4p. Previously, we demonstrated that Ste20p forms a complex with Erg4p, Cbr1p and Ncp1p, which all catalyze important steps in sterol biosynthesis. CLA4 interacts genetically with ERG4 and NCP1. Furthermore, Erg4p, Ncp1p and Cbr1p play important roles in cell polarization during vegetative growth, mating and filamentation. As Ste20p and Cla4p are involved in these processes it seems likely that sterol biosynthetic enzymes and p21‐activated kinases act in related pathways. Here, we demonstrate that the deletion of either STE20 or CLA4 results in increased levels of sterols. In addition, higher concentrations of steryl esters, the storage form of sterols, were observed in cla4Δ cells. CLA4 expression from a multicopy plasmid reduces enzyme activity of Are2p, the major steryl ester synthase, under aerobic conditions. Altogether, our data suggest that Ste20p and Cla4p may function as negative modulators of sterol biosynthesis. Moreover, Cla4p has a negative effect on steryl ester formation. As sterol homeostasis is crucial for cell polarization, Ste20p and Cla4p may regulate cell polarity in part through the modulation of sterol homeostasis.

Structured digital abstract

MINT‐7291456: STE20 (uniprotkb:Q03497) physically interacts (MI:0915) with CBR1 (uniprotkb:P38626) by ubiquitin reconstruction (MI:0112)

MINT‐7291480: STE20 (uniprotkb:Q03497) physically interacts (MI:0915) with BEM1 (uniprotkb:P29366) by ubiquitin reconstruction (MI:0112)

MINT‐7291468: STE20 (uniprotkb:Q03497) physically interacts (MI:0915) with NCP1 (uniprotkb:P16603) by ubiquitin reconstruction (MI:0112)

MINT‐7291441: STE20 (uniprotkb:Q03497) physically interacts (MI:0915) with ERG4 (uniprotkb:P25340) by ubiquitin reconstruction (MI:0112)

MINT‐7291492: CLA4 (uniprotkb:P48562) physically interacts (MI:0915) with BEM1 (uniprotkb:P29366) by ubiquitin reconstruction (MI:0112)

MINT‐7291412: STE20 (uniprotkb:Q03497) physically interacts (MI:0915) with ARE1 (uniprotkb:P25628) by pull down (MI:0096)

MINT‐7291424: STE20 (uniprotkb:Q03497) physically interacts (MI:0915) with ARE2 (uniprotkb:P53629) by pull down (MI:0096)
First high-resolution detection of a warm absorber in the Broad Line Radio Galaxy 3C 382
Authors: Torresi E. , Grandi P. , Longinotti A. L. , Guainazzi M. , Palumbo G. G. C. , Tombesi F. , Nucita A.
Published: November 2009

Recent high-resolution measurements suggest that the soft X-ray spectrum of obscured radio galaxies exhibits signatures of photoionized gas (e.g. 3C 445 and 3C 33) similar to those observed in radio-quiet obscured active galactic nuclei. While signatures of warm absorbing gas covering a wide range of temperature and ionization states have been detected in about one-half of the population of nearby type 1 Seyfert galaxies, no traces of warm absorber gas have been reported to date in the high-resolution spectra of broad-line radio galaxies (BLRG). We present here the first detection of a soft X-ray warm absorber in the powerful Fanaroff–Riley type II BLRG 3C 382 using the Reflection Grating Spectrometer on-board XMM–Newton. The absorption gas appears to be highly ionized, with column density of the order of 1022 cm−2, ionization parameter log ξ > 2 erg cm s−1 and outflow velocities of the order of 103 km s−1. The absorption lines may come from regions located outside the torus, however, at distances less than 60 pc. This result may indicate that a plasma ejected at velocities near the speed of light and a photoionized gas with slower outflow velocities can coexist in the same source beyond the broad-line regions.
BP NEURAL NETWORK FOR EVALUATING SENSORY TEXTURE PROPERTIES OF COOKED SAUSAGE
Authors: DONG QING‐LI
Published: November 2009

In order to replace sensory evaluation by instrumental measurement with more accuracy for texture properties of cooked sausage, correlation analysis between sensory and instrumental texture was established by multiple regression and back propagation (BP) neural network, respectively. Effect of different fat, salt, moisture and starch addition on the texture of cooked sausage was also investigated in this paper. It indicated that the accuracy and goodness of fit of predicting sensory hardness, cohesiveness and juiciness by BP neural network were more significant than those by multiple regressions with lower root mean square error and standard error of prediction. Although both accuracy and bias factors of two models were in acceptable range, BP neural network provides an accurate and selective method for predicting sensory texture evaluation in similar meat products.

PRACTICAL APPLICATIONS

The effect of different fat, salt, moisture and starch addition on textural properties of cooked sausage could be valuable to the meat industry in order to select the appropriate components for improving the texture of sausage. Artificial neural network technology used in this study can be useful for the fast, on‐time and convenient detection of texture measurement by instrumental instead of sensory evaluation.
ASSESSING CONSUMER EXPECTATIONS FOR FOOD BARS BY CONJOINT ANALYSIS
Authors: MAHANNA K. , MOSKOWITZ H.R. , LEE S.‐Y.
Published: November 2009

Food bars, which include meal replacement, protein, granola and cereal bars, have rapidly increased in sales with current estimation of above $3.2 billion. Despite such rapid growth in the market, research on consumer expectations for these products is still lacking. Conjoint analysis was used to probe the effect of different elements of food bar products on purchase intent, including types of bar, ingredients, macro‐nutrients, health claims, calories and sensory characteristics. Overall, consumers wanted a food bar to be less than 150 kcal, made with whole grains and higher in protein. Consumers divided into four mind‐set segments were characterized as “Label Readers” (n = 213), “Calorie Health Nuts” (n = 90), “Flavor Energy Seekers” (n = 79) and “Chocolate Lovers” (n = 44). Sensory characteristics and types of bar categories were not important to consumers, although calorie elements played the largest role in motivating purchase intent for food bars.

PRACTICAL APPLICATIONS

The results found from this research help to guide new product development in the food bar market by identifying the desires of specific consumer segments. Consumers were interested in food bar products with lower calorie content, which supports the idea that food bars are more typically consumed as a snack than a meal replacement. Half of the sample consumers tested belonged to the “Label Readers” segment. These consumers are interested in a healthful food bar product high in fiber. Development of a bar that is considered healthful would appeal not only to the “Label Readers” segment, but also to the “Calorie Health Nuts” segment. When developing a food bar product, the labeled bar type or sensory claims are not important to consumers. Consumers are more interested in the ingredients and caloric content of the food bar.
SENSORY APPROACH TO MEASURE FRAGRANCE INTENSITY ON THE SKIN
Authors: CORTEZ‐PEREIRA CLAUDIA SILVA , BABY ANDRÉ ROLIM , KANEKO TELMA MARY , VELASCO MARIA VALÉRIA ROBLES
Published: November 2009

Sensory analysis is a precise and descriptive measuring technique to quantify human responses to stimuli. Odor, one of these stimuli, is basically the result of the interaction between a chemical stimulus and the olfactory receptor system, which can be described using a number of different dimensions and measures through different sensory tests: threshold, intensity and quality. To measure fragrance performance on the skin, these parameters are very important, but the main attribute to be evaluated is substantivity, thus the importance of the sensory scale chosen to measure perception, discriminate different intensities and determine the substantivity of the fragrance. Some studies comparing the labeled magnitude scale (LMS) with other magnitude scales and their derivations showed that the use of the LMS scale to measure fragrance intensity could semantically understand the intensity of the stimulus. Tests using this scale confirmed the applicability and efficiency of the LMS.

PRACTICAL APPLICATIONS

The objective of this article is to review the techniques used to measure odor and fragrance intensities applied on the skin. The review shows general sensory techniques and their goals, the newest olfactory mechanism and its contribution to sensory evaluation and which attributes should be considered to measure odor. Substantivity/retentivity or longevity can be regarded as the most important attributes if you want to measure fragrance performance on the skin. Past studies showed different scales tested to measure odor, and some of them demonstrated that the labeled magnitude scale is very suitable to measure fragrance on the skin.
CONSUMER PERCEPTION OF FAT REDUCTION IN CHEESE
Authors: CHILDS JESSICA L. , DRAKE MARYANNE
Published: November 2009

The objective of this study was to quantitatively assess the consumer perception of fat reduction in cheese. Choice‐based conjoint analysis surveys for Cheddar and mozzarella cheeses (n = 179 and 171 consumers, respectively) were developed using results from focus groups conducted with users and nonusers of lower fat cheeses. Factors investigated were fat content, flavor, texture and price of cheese. Relative importance of product attributes was determined through a realistic trade‐off scenario. Consumer acceptance testing (n = 101) was then conducted on Cheddar and mozzarella cheeses with varying levels of fat reduction. Conjoint analysis results suggested that a 2% milk Cheddar cheese would be most appealing among fat reduced Cheddar cheeses and that a part‐skim mozzarella would be more appealing than a fat‐free mozzarella, and these results were confirmed by consumer acceptance testing. These results confirm that most consumers are not willing to sacrifice flavor or texture for fat reduction in cheeses. Significant changes in flavor and texture are needed for a low‐fat Cheddar cheese to have widespread consumer appeal.

PRACTICAL APPLICATIONS

This study found that most consumers are not accepting of lower fat Cheddar or mozzarella cheeses when their flavor and texture are different from the full‐fat version of the cheese, even if those differences are small. These results are in contrast to the rise in obesity in the United States, consumer interest in fat‐reduced foods and industry and government interest in offering sensible lower fat versions of foods. For a true low‐fat version of Cheddar cheese to have widespread consumer appeal, significant changes in flavor and texture are required. These results will help cheese manufacturers understand what changes need to be made in order to successfully develop a lower fat cheese that will appeal to consumers. In addition, if manufacturers are able to provide this product, consumers will be able to purchase and consume a lower fat cheese that they enjoy and feel good about eating.
Economic Diversity and Regional Socioeconomic Performance: An Empirical Analysis of the Western Australian Grain Belt
Authors: DAVIES AMANDA , TONTS MATTHEW
Published: November 2009

One of the truisms ingrained in much regional development policy and practice is the claimed importance of economic diversity in contributing to socio‐economic stability and well‐being. There is, however, very little recent research examining this contention in the context of rural Australia. This paper examines the extent to which economic diversity affects the socio‐economic performance of local areas in the Western Australian grain belt. The results indicate that employment diversity across industry sectors is clearly associated with population growth, labour force expansion, labour force participation, and rising median incomes. However, the paper also argues that economic diversity is not necessarily the cause of these changes, but simply one, albeit important, component of the dynamics of regional change.
Relationship between vegetation of the levee neo‐ecosystems and environmental heterogeneity in the Lower Delta of the Paraná River, Argentina
Authors: Kalesnik Fabio , Aceñolaza Pablo , Hurtado Martín , Martínez Jorge
Published: November 2009

The relationship between environmental heterogeneity and the vegetation of the levee neo‐ecosystems in the Delta of the Paraná River was studied. These habitat types were considered plant communities of recent origin related to local productive activities. Vegetation coverage was evaluated in 97 plots of three different environmental units (A, B and C), using classification analysis, indirect and direct ordinations. The differential vegetation in different environmental units could be related to a greater fluvial influence of the Paraná River on unit A and a greater tidal influence of the de la Plata River on units B and C. The Lower Delta hydrological regimes only affect a few of edaphic variables particularly pH, organic matter percentage and clay content. To understand the spatial pattern of neo‐ecosystems vegetation, it is also necessary to consider the invasion of alien species that has been taking place for over 50 years.
Presumptive caudal cerebellar artery infarct in a dog: clinical and MRI findings
Authors: Negrin A. , Gaitero L. , Añor S.
Published: November 2009

Clinical signs and magnetic resonance imaging findings of a caudal cerebellar artery infarct are reported for the first time in a dog. Clinical signs were characterised by a peracute, non‐progressive, right‐sided central vestibular syndrome with paradoxical right‐sided head tilt. Magnetic resonance images were consistent with a territorial, non‐haemorrhagic, ischaemic lesion affecting the caudo‐ventral part of the right cerebellar hemisphere, mainly involving the right paramedian lobe, the ansiform lobe and the caudal cerebellar peduncle. Bloodwork results were suggestive of an underlying hypercoagulable state, although the concomitant presence of a histologically confirmed mammary gland adenocarcinoma could have also been related to the cerebellar vascular obstruction through metastatic emboli formation. Posterior‐inferior cerebellar artery infarction is the human equivalent of caudal cerebellar artery infarct in dogs.
Feline extranodal lymphoma: response to chemotherapy and survival in 110 cats
Authors: Taylor S. S. , Goodfellow M. R. , Browne W. J. , Walding B. , Murphy S. , Tzannes S. , Gerou‐Ferriani M. , Schwartz A. , Dobson J. M.
Published: November 2009

Objective:To determine response to treatment, survival and prognostic factors for feline extranodal lymphoma in the UK.

Methods:Records of cats diagnosed with lymphoma of extranodal sites at seven referral centres were reviewed and information on signalment, tumour location, prior treatment and chemotherapy protocol recorded. Factors influencing response to treatment and survival were assessed.

Results:One hundred and forty‐nine cases met inclusion criteria. Sixty‐nine cats had nasal lymphoma, 35 renal, 15 central nervous system, 11 laryngeal and 19 miscellaneous locations. Sixty‐six cats received cyclophosphamide, vincristine, prednisolone, 25 Wisconsin‐Madison doxorubicin‐containing multi‐agent protocol, 10 prednisolone alone and nine other combinations. The response rate for the 110 treated cats was 85·5 per cent. Of cyclophosphamide, vincristine, prednisolone treated cats 72·7 per cent achieved complete remission, median survival 239 days. Sixty‐four per cent of Wisconsin‐Madison treated cats achieved complete remission, median survival 563 days. Cats with nasal lymphoma achieving complete remission had the longest survival (749 days) and cats with central nervous system lymphoma the shortest (70 days). If complete remission was achieved, prior treatment with corticosteroids significantly reduced survival time.

ClinicalSignificance:Cats with extranodal lymphoma respond to chemotherapy and achieve survival times comparable to other locations. Corticosteroid pretreatment reduced survival time in cats achieving complete remission.
Weight loss and incretin responsiveness improve glucose control independently after gastric bypass surgery
Authors: BOSE Mousumi , TEIXEIRA Julio , OLIVAN Blanca , BAWA Baani , ARIAS Sara , MACHINENI Sriram , PI‐SUNYER F. Xavier , SCHERER Philipp E. , LAFERRÈRE Blandine
Published: November 2009

Background:  The aim of the present study was to determine the mechanisms underlying Type 2 diabetes remission after gastric bypass (GBP) surgery by characterizing the short‐ and long‐term changes in hormonal determinants of blood glucose.

Methods:  Eleven morbidly obese women with diabetes were studied before and 1, 6, and 12 months after GBP; eight non‐diabetic morbidly obese women were used as controls. The incretin effect was measured as the difference in insulin levels in response to oral glucose and to an isoglycemic intravenous challenge. Outcome measures were glucose, insulin, C‐peptide, proinsulin, amylin, glucagon, glucose‐dependent insulinotropic polypeptide (GIP), glucagon‐like peptide‐1 (GLP‐1) levels and the incretin effect on insulin secretion.

Results:  The decrease in fasting glucose (r = 0.724) and insulin (r = 0.576) was associated with weight loss up to 12 months after GBP. In contrast, the blunted incretin effect (calculated at 22%) that improved at 1 month remained unchanged with further weight loss at 6 (52%) and 12 (52%) months. The blunted incretin (GLP‐1 and GIP) levels, early phase insulin secretion, and other parameters of β‐cell function (amylin, proinsulin/insulin) followed the same pattern, with rapid improvement at 1 month that remained unchanged at 1 year.

Conclusions:  The data suggest that weight loss and incretins may contribute independently to improved glucose levels in the first year after GBP surgery.
Validation and Quantitative Assessment of the Deterioration Mechanisms of Arctic Icebergs
Authors: El-Tahan M. , Venkatesh S. , El-Tahan H.
Published: November 2009

In this paper the important mechanisms affecting the deterioration of Arctic icebergs are modeled based on parameterizations developed for the International Ice Patrol. The model simulations of the deterioration of three icebergs in the Grand Banks/Labrador Sea area off the Canadian east coast are compared with observations. The model parameterizations provide a reasonable approximation of iceberg deterioration with best results being obtained where detailed observations of the above-water and underwater portions of the iceberg are available enabling accurate estimations of iceberg mass and other parameters needed for the model. A quantitative assessment of the deterioration of icebergs in the Grand Banks/Labrador Sea area is also carried out for each month of the year when the sea surface temperature was above zero. Wave erosion is found to be the major deterioration mechanism. Wave erosion and the resulting calving of overhanging slabs together account for more than 80 percent of the deterioration rate. A small iceberg drifting on the Grand Banks could lose up to one third of its mass in one day.
Horizontal Forces on a Submerged Wave-Energy Structure in Shallow Water
Authors: Morrison D. G. , Geustyn L. C. , Zietsman J.
Published: November 2009

This study was done to determine horizontal design forces on a submerged wave-energy structure in relatively shallow water. Experimental data was compared with calculated horizontal force values. Trends in the experimental data compared favorably with calculations, and formed the basis for design forces in a range of water depth to structure height ratios for which previous data has not been published.
Nonlinear Axisymmetric Static Analysis of Shallow Spherical Shells on Winkler-Pasternak Foundation
Authors: Jain R. K. , Nath Y.
Published: November 2009

In the present investigation nonlinear static analysis of thin axisymmetric circular plates, annular plates and shallow spherical shells resting on linear elastic Winkler-Pasternak foundation under uniformly distributed normal loads, has been carried out. Donnell-type governing differential equations expressed in terms of normal displacement and stress function have been employed and solved using Chebyshev series. A convergence study for Chebyshev series has been conducted. The influence of foundation stiffness parameters (K and G) on the response of circular plates, annulus and spherical shells has been studied for both the clamped and simply supported immovable edge conditions. A few typical snap-through results for shells are also included.
Notch Ductilities of Rich Natural Gas Transmission Line Pipes for Arresting Propagating Shear Fracture
Authors: Sugie E. , Matsuoka M. , Akiyama T. , Tanaka K. , Kawaguchi Y.
Published: November 2009

High Strength Line Pipe Research Committee organized by The Iron and Steel Institute of Japan carried out two full-scale burst tests on X70 line pipes, 48 in. o.d. × 0.720 in. w.t., with rich natural gas as the pressurizing gas. A theoretical investigation which gives the crack velocity change in terms of the crack velocity curve and the gas decompression velocity curve is presented, and the theoretical predictions and the experimental results are in good agreement. The developed method can predict the required notch ductilities obtained from Charpy test and DWTT in order to arrest a propagating shear fracture according to the type of gas, design stress and acceptable fracture length in the pipeline.
Transverse Vibrations of a Cylinder Very Close to a Plane Wall
Authors: Fredso̸e J. , Sumer B. M. , Andersen J. , Hansen E. A.
Published: November 2009

The paper presents a series of experiments carried out with a cylinder suspended by springs and placed very close to a plane wall. The cylinder is exposed to a steady current. The range of gap ratios between zero and one has been studied in detail. Different combinations of spring stiffness and mass of cylinder is applied in the range of reduced velocity between 2 and 10. The proximity of the wall is shown to have important influence on the behavior of the pipe. Some of these trends are explained by a mathematical model including the effect of lift force close to the wall.
Study on Dynamic Responses of a TLP in Waves
Authors: Kobayashi M. , Shimada K. , Fujihira T.
Published: November 2009

The dynamic responses of a TLP (Tension Leg Platform) in regular and irregular waves were investigated by model tests and calculations in both frequency and time domain. Hydrodynamic forces in regular waves were calculated by the three-dimensional singularity distribution method. Furthermore, a contribution of the fluid viscosity to wave drift force was discussed. Usefulness of the time history simulation was confirmed in the comparison between experimental and calculated time traces.
A Flexural and Longitudinal Elastic Wave Propagation Theory Applied to Ice Floe Impact With Sloping Structures
Authors: Luk C. H.
Published: November 2009

This paper presents a one-dimensional flexural and longitudinal elastic wave propagation theory for analysis of ice floe impact with a rigid structure having a constant slope. In this paper, governing differential equations were derived following the Timoshenko beam theory which includes the rotary inertia and shear deformation of the ice beam, as well as the buoyancy effect of the water. The ice material was treated as a homogeneous, isotropic, and linearly elastic solid. Interactions between the longitudinal and flexural waves in the ice sheet, and the boundary conditions imposed by the rigid slope, have been considered. Solution procedures were developed based on the method of characteristics using a fixed grid finite difference approximation in both space and time. Computer solutions were obtained and plots were provided to show ice impact force-time histories and the wave propagation phenomenon for a range of floe impact problems of current interest. Comparisons were also made with other existing methods for calculating ice bending loads on sloping structures.
An Apparent Free Surface Method for Determining the Transient Freezing Around a Buried Pipe in a Semi-Infinite Region
Authors: Weinbaum S. , Zhang G-P. , Jiji L. M.
Published: November 2009

A new quasi-steady analytic solution procedure is introduced for determining the noncircular growth of the freeze/thaw boundary around a buried pipe in a half space for the case where the pipe wall temperature is a slowly varying function of time and the freezing/thawing commences at the surface of the pipe. All previous approximate analytic solutions have been based on the critical assumption that all isotherms including the thaw boundary at each instant were eccentric circles belonging to the bicircular coordinate transformation containing the tube wall and the free surface. It is first shown that this assumption is a poor approximation, except as the asymptotic steady state is reached, and that the curvatures of the upper and lower portions of the thaw boundary will grow at vastly different rates except at very early times. A new solution methodology is proposed based on the concept of a virtual free surface. This solution permits the lower portion of the thaw front (i) to develop at a different rate than the upper region and (ii) to undergo a continuous transition in behavior from the infinite burial depth solution at early times to the asymptotic bicircular steady state solution at large times.
Limit State Philosophy in Pipeline Design
Authors: Ellinas C. P. , Raven P. W. J. , Walker A. C. , Davies P.
Published: November 2009

This paper considers the application of the limit state philosophy of structural analysis to pipeline design. General aspects of the philosophy are discussed and the approach to the evaluation of safety factors is reviewed. The paper further considers the various limit and serviceability states which would be relevant to a pipeline and reviews the various factors which may require consideration, before a code embodying the limit state philosophy could be formulated. A review of the state of current knowledge on various aspects of geometry and material characteristics, loading and structural behavior is presented. It is intended that such a review can be used as the basis for a larger study to provide guidance and data for the evaluation of rational levels of safety factor. The major conclusion reached by the authors is that a limit state philosophy would be valuable in providing a suitable framework, which may highlight the significant aspects of pipeline design and which can most easily accommodate new requirements and results obtained from research.
Wave Loads and Motions of Long Structures in Directional Seas
Authors: Isaacson M. , Nwogu O. U.
Published: November 2009

The present paper deals with the effects of wave directionality on the loads and motions of long structures. A numerical procedure based on Green’s theorem is developed to compute the exciting forces and hydrodynamic coefficients due to the interaction of a regular oblique wave train with an infinitely long, semi-immersed floating cylinder of arbitrary shape. The linear transfer function approach is used to determine the wave loads and motions of a structure of finite length in short-crested seas. The effect of wave directionality is expressed as a frequency-dependent, directionally averaged reduction factor for the wave loads and a response ratio for the body motions. Numerical results are presented for the force reduction factor and response ratio of a long floating box subject to a directional wave spectrum with a cosine-power-type energy spreading function.
Statistical Properties of Directional Sea Measurements
Authors: Stansberg C. T.
Published: November 2009

The statistical variability of directional sea estimates is considered. A general, but brief study in the mean and variance of the spatial coherence estimate is first presented. This function is found to be relatively unstable when it is not close to 1. A directional sea estimation procedure based on Fourier Series Expansion of the directional spectrum combined with a Maximum Entropy Condition is then described. This method is used in a numerical directional analysis test in order to demonstrate the effect on sea state estimates from the variability in the spatial coherence. Numerical sea states for this test are generated with 2049 frequencies and 100 directions per frequency. Significant statistical scatter is observed in the resulting estimated directional spectra and their parameters, in qualitative agreement with the spatial coherence statistics considered theoretically.
Stability Analysis to Predict Vortex Street Characteristics and Forces on Circular Cylinders
Authors: Triantafyllou G. , Triantafyllou M. , Chryssostomidis C.
Published: November 2009

The characteristics of the wake are predicted accurately by the critical point of the absolute instability supported by the wake profiles immediately behind the cylinder. Measured profiles at Rn = 56 provide Strouhal number St = 0.13 and at Rn = 140,000 St = 0.21 both in good agreement with experiment. It is also shown that at the undercritical Rn = 34 or for a symmetric array of vortices the instability is of the convective type, decaying behind the cylinder once the excitation is removed. Finally, it is shown that a model of the wake, based on the results of the instability analysis, is sufficient to obtain good estimates of the steady and unsteady forces on the cylinder. Closed-form expressions for the forces are obtained within this approximation.
On the Length of the Transition Zone in Unconfined Buckle Propagation
Authors: Bhat S. U. , Wierzbicki T.
Published: November 2009

When a buckle propagates down an underwater pipeline due to excessive hydrostatic pressure, the permanent plastic deformations and sectional collapse of the tube are restricted to a finite length transition zone. The existing theoretical predictions of the propagation pressure Pp are based on ring models neglecting the axial effects in the transition zone. An analysis of the transition phenomenon has not been reported so far. The present paper analyzes the transition zone in an unconfined propagating buckle using a simple model of the pipe consisting of rings and stringlike generators. The thrust of this paper is toward establishing a basic understanding of the transition phenomenon, necessary to improve the theoretical predictions of the propagation pressure further. Expressions for the length of the transition zone have been derived in terms of the material and geometric parameters of the pipe. The results are compared with limited experimental data kindly provided to us by Kyriakides.
Analyzing Numerical Errors in Domain Heat Transport Models Using the CVBEM
Authors: Hromadka T. V.
Published: November 2009

Besides providing an exact solution for steady-state heat conduction processes (Laplace-Poisson equations), the CVBEM (complex variable boundary element method) can be used for the numerical error analysis of domain model solutions. For problems where soil-water phase change latent heat effects dominate the thermal regime, heat transport can be approximately modeled as a time-stepped steady-state condition in the thawed and frozen regions, respectively. The CVBEM provides an exact solution of the two-dimensional steady-state heat transport problem, and also provides the error in matching the prescribed boundary conditions by the development of a modeling error distribution or an approximate boundary generation. Consequently, this error evaluation can be used to develop highly accurate CVBEM models of the heat transport process, and the resulting model can be used as a test case for evaluating the precision of domain models based on finite elements or finite differences.
Robust Self-Designing Controllers for Underwater Vehicles
Authors: Goheen K. R. , Jefferys E. R. , Broome D. R.
Published: November 2009

Conventional multivariable and adaptive controllers are hard to design for Remotely Operated Underwater Vehicles (ROVs) because their dynamics are strongly coupled, highly nonlinear and vary according to the vessel’s operating configuration. An alternative design procedure which combines some of the ideas of adaptive and robust control is based on a “self-test” which the vehicle can be programmed to execute autonomously. The resulting controller is evaluated by examining its closed-loop poles, responses to step changes in reference inputs and rejection of disturbances caused by turbulence.
An Analysis of Water Shipping Between Two Floating Platforms in the Beam Waves
Authors: Fang M.-C. , Kim C. H.
Published: November 2009

This paper presents a frequency domain method for predicting the relative wave elevation due to the hydrodynamic interaction between two floating structures in the beam waves. The strip method has been found to be a practically useful technique to analyze the hydrodynamically coupled motions of two parallel structures in waves. The two-dimensional procedure which is an integral equation method is therefore used in this paper. The present study uses the linearized resultant pressure including the interaction effect to calculate the wave elevation. Both diffraction and radiation cases are considered. The relative wave elevations at each hull are investigated and the wave elevation amplitudes along the sea surface between two structures are also analyzed. It was found that some significant waves occur at the coupled resonance of the body motion. Therefore, the water shipping must be considered as an important factor for the safety of cargo transfer problem. The results shown in the paper may be regarded as analytically reasonable from the viewpoint of energy conservation.
The Effect of Tether Damage on Tension Leg Platform Dynamics
Authors: Booton M. , Joglekar N. , Deb M.
Published: November 2009

The design of a tension leg platform (TLP) provides for tethers of equal stiffness at each corner. Damage to the tethers results in a loss of stiffness and consequently a change in the static equilibrium configurations and dynamic response of the platform and also affects the tether dynamics. Computer algorithms for the linear and nonlinear analysis of a tension leg platform subjected to regular waves have been developed assuming that the platform is modeled as a rigid body. In the linear case the tethers are modeled as one-degree of freedom springs whereas in the nonlinear study the tethers are modeled as a network of beam elements having bending and axial stiffness and also geometric stiffness because of the large displacements assumed. It is assumed that the hydrodynamic forces on the assembled structure equal the sum of the hydrodynamic forces on the component bodies while their interaction is ignored. A parametric study of the platform motion responses and tension variations has been presented for cases involving the loss of tether stiffness. Motion responses of the platform and the tension at each leg have been computed for a regular wave traveling from aft to forward for cases involving intact tethers and with a certain amount of stiffness lost, in one instance at both aft tethers, and in another case at only the aft starboard tether. A regular wave of 10.0-m height and 8.0-s period in 160-m water depth has been used for calculation purposes. The total mean pretension is assumed to remain constant. It is seen that the lateral motions of the platform (such as surge) are not affected by the loss of tether stiffness while the motions in the vertical plane (such as heave and pitch) increase with reduction in stiffness. In all cases the dynamic tension amplitude increases with loss of tether stiffness. For a given configuration, the nonlinear analysis yielded larger dynamic tension amplitudes than those obtained from linear analysis because of the inclusion of bending stiffness in the tethers and also because large displacements were taken into account.
Constitutive Modeling of Sea Ice
Authors: Chen V. , Chen E. S. , Vivatrat V.
Published: November 2009

Realistic constitutive models for ice are necessary for reliable prediction of ice loads and ice-structure interaction. Previous analytical work has tended to concentrate on ice behavior at low strain rates. Under high strain rates, the post peak softening behavior becomes more important than rate-dependency. This paper proposes a new constitutive model for ice under high strain rates, incorporating strain softening and pressure sensitivity. In its present form, the model is incrementally linear and can be easily implemented in a finite element computer program to solve monotonic loading problems.
Predicting Incipient Jumps to Resonance of Compliant Marine Structures in an Evolving Sea-State
Authors: Bishop S. R. , Leung L. M. , Virgin L. N.
Published: November 2009

When monitoring the wave-driven motions of a compliant offshore facility, be it an articulated mooring tower or a vessel, the engineer would like to be able to predict, in real time, any incipient jump to resonance that might be imminent due to the slowly evolving sea-state. We explore in this paper a study of some new possible prediction techniques for both a jump to a main fundamental resonance leading to capsize and a flip bifurcation to a subharmonic resonance. Stroboscopic Poincare´ mapping techniques based on discrete time sampling are used to give information about the approach to instability. The first application of these techniques is in the prediction of the jump in resonance and consequent capsize at a cyclic fold in the roll response of a vessel in regular beam seas. Secondly, the techniques are shown to work extremely well in a variety of computational situations when applied to the simulation of an articulated mooring tower during the approach to the potentially dangerous oscillations produced by the onset of subharmonic resonance at a flip bifurcation, in both regular and irregular ocean waves.
Linear Dynamics of Flexible Risers
Authors: Patrikalakis N. M. , Kriezis G. A.
Published: November 2009

The objective of this paper is to present solutions for the linear dynamics of flexible risers using a novel combination of efficient embedding and asymptotic techniques. Numerical examples for a buoyant flexible riser are included and the effects of the principal parameters are discussed. Finally, a numerical scheme employing the linear solutions to develop a solution of the nonlinear problem is outlined.
Calculation of Stresses and Slip in Structural Layers of Unbonded Flexible Pipes
Authors: Fe´ret J. J. , Bournazel C. L.
Published: November 2009

This paper deals with the behavior of high-pressure unbonded flexible steel pipes which can be used as risers in offshore applications. It concerns primarily the behavior of the internal structure of the pipe. A theoretical approach allows to establish simple formulas for evaluating: the stresses, and the contact pressures between layers due to axisymmetrical loads; the stresses due to bending; the relative slip between layers due to bending. This is a first step towards the evaluation of the life expectancy of flexible pipes. It must be completed by the determination of friction and wear factors through test results.
Probabilistic Collapse Analysis of Offshore Structure
Authors: Murotsu Y. , Kishi M. , Okada H. , Ikeda Y. , Matsuzaki S.
Published: November 2009

This paper proposes a method for probabilistic collapse analysis of an offshore structure. Wave loads are estimated by using Stokes third-order theory and Morison’s formula. Plastic collapsing is evaluated by taking account of the combined load effect to generate the safety margins, using a matrix method. Probabilistically dominant collapse modes are selected through a branch-and-bound method. The proposed method is successfully applied to a jacket-type offshore platform.
A Method to Upgrade Iceberg Velocity Statistics to Include Wave-Induced Motion
Authors: Lever J. H. , Sen D.
Published: November 2009

Iceberg impact design loads for offshore structures can be estimated by incorporating an ice/structure interaction model in a probabilistic framework, or risk analysis. The relevant iceberg and environmental parameters are input in statistical form. Iceberg velocity statistics are usually compiled from drilling rig radar reports, and hence represent estimates of average hourly drift speeds. Yet it is the instantaneous ice velocity which is the relevant input to the simulation of the iceberg/structure collision process. Thus, risk analyses based on mean drift speed distributions will only yield valid results for the subset of conditions where wave-induced iceberg motion is negligible. This paper describes a method which, for the first time, systematically accounts for wave-induced motion in iceberg impact risk analyses. A linear three-dimensional potential flow model is utilized to upgrade iceberg velocity statistics to include the influence of Grand Banks sea-state conditions on instantaneous ice motion. The results clearly demonstrate the importance of including wave-induced motion in iceberg impact risk analyses.
On Wave Force Coefficient Variability
Authors: Nath J. H.
Published: November 2009

Wave force coefficient variability for cylinders, from wave to wave in a train of periodic waves, has been shown to be dependent on the phase of the force record relative to the ambient flow. The phase varies due to vortex shedding, but the maximum force is approximately constant as seen from this work and the work of other investigators. Thus, the maximum force coefficient is tightly organized according to the Keulegan-Carpenter number and scatter is seen in the phase angle versus Keulegan-Carpenter number. On the other hand, both Cd and Cm have scatter due to these phase differences from wave to wave. For unknown reasons, even when averaged over several wave cycles there is scatter in the results for Cd and Cm. This investigation shows that the maximum force coefficients for a heavily roughened vertical cylinder are tightly arranged according to the Keulegan-Carpenter number and the period parameter. Furthermore, the phase angle is similarly much more organized than for the smooth cylinder.