bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal Design of an Elastic Plate with Unilateral Elastic Foundation and Rigid Supports, Using the Reissner‐Mindlin Plate Model. I: Continuous Problems
Authors: Hlaváček I. , Lovíšek J. 
Published: June 2007

AbstractSeveral optimal design problems with a variational inequality with a monotone operator as common state problem are considered. The inequality represents the bending of a Reissner‐Mindlin plate, resting on a unilateral elastic foundation and on some unilateral rigid piers. Both the thickness of the plate and the stiffness of the foundation play the role of design variables. The cost functionals include the intensity of shear stresses, and reactive forces on the piers or the weight of the plate. The solvability of all the problems is proved.
The Triploid Endosperm Genome ofArabidopsisAdopts a Peculiar, Parental-Dosage-Dependent Chromatin Organization
Authors: Baroux Célia , Pecinka Ales , Fuchs Jörg , Schubert Ingo , Grossniklaus Ueli 
Published: June 2007

AbstractThe endosperm is a seed tissue unique to flowering plants. Due to its central role in nourishing and protecting the embryo, endosperm development is subject to parental conflicts and adaptive processes, which led to the evolution of parent-of-origin–dependent gene regulation. The role of higher-order chromatin organization in regulating the endosperm genome was long ignored due to technical hindrance. We developed a combination of approaches to analyze nuclear structure and chromatin organization in Arabidopsis thaliana endosperm. Endosperm nuclei showed a less condensed chromatin than other types of nuclei and a peculiar heterochromatin organization, with smaller chromocenters and additional heterochromatic foci interspersed in euchromatin. This is accompanied by a redistribution of the heterochromatin mark H3K9me1 from chromocenters toward euchromatin and interspersed heterochromatin. Thus, endosperm nuclei have a specific nuclear architecture and organization, which we interpret as a relaxed chromocenter-loop model. The analysis of endosperm with altered parental genome dosage indicated that the additional heterochromatin may be predominantly of maternal origin, suggesting differential regulation of maternal and paternal genomes, possibly linked to genome dosage regulation.
A Heteromeric Plastidic Pyruvate Kinase Complex Involved in Seed Oil Biosynthesis inArabidopsis
Authors: Andre Carl , Froehlich John E. , Moll Matthew R. , Benning Christoph 
Published: June 2007

AbstractGlycolysis is a ubiquitous pathway thought to be essential for the production of oil in developing seeds of Arabidopsis thaliana and oil crops. Compartmentation of primary metabolism in developing embryos poses a significant challenge for testing this hypothesis and for the engineering of seed biomass production. It also raises the question whether there is a preferred route of carbon from imported photosynthate to seed oil in the embryo. Plastidic pyruvate kinase catalyzes a highly regulated, ATP-producing reaction of glycolysis. The Arabidopsis genome encodes 14 putative isoforms of pyruvate kinases. Three genes encode subunits α, β1, and β2 of plastidic pyruvate kinase. The plastid enzyme prevalent in developing seeds likely has a subunit composition of 4α4β1, is most active at pH 8.0, and is inhibited by Glu. Disruption of the gene encoding the β1 subunit causes a reduction in plastidic pyruvate kinase activity and 60% reduction in seed oil content. The seed oil phenotype is fully restored by expression of the β1 subunit–encoding cDNA and partially by the β2 subunit–encoding cDNA. Therefore, the identified pyruvate kinase catalyzes a crucial step in the conversion of photosynthate into oil, suggesting a preferred plastid route from its substrate phosphoenolpyruvate to fatty acids.
Structural Evidence for the Evolution of Xyloglucanase Activity from Xyloglucan Endo-Transglycosylases: Biological Implications for Cell Wall Metabolism
Authors: Baumann Martin J. , Eklöf Jens M. , Michel Gurvan , Kallas Åsa M. , Teeri Tuula T. , Czjzek Mirjam , Brumer Harry 
Published: June 2007

Abstract
High-resolution, three-dimensional structures of the archetypal glycoside hydrolase family 16 (GH16) endo-xyloglucanases Tm-NXG1 and Tm-NXG2 from nasturtium (Tropaeolum majus) have been solved by x-ray crystallography. Key structural features that modulate the relative rates of substrate hydrolysis to transglycosylation in the GH16 xyloglucan-active enzymes were identified by structure–function studies of the recombinantly expressed enzymes in comparison with data for the strict xyloglucan endo-transglycosylase Ptt-XET16-34 from hybrid aspen (Populus tremula × Populus tremuloides). Production of the loop deletion variant Tm-NXG1-ΔYNIIG yielded an enzyme that was structurally similar to Ptt-XET16-34 and had a greatly increased transglycosylation:hydrolysis ratio. Comprehensive bioinformatic analyses of XTH gene products, together with detailed kinetic data, strongly suggest that xyloglucanase activity has evolved as a gain of function in an ancestral GH16 XET to meet specific biological requirements during seed germination, fruit ripening, and rapid wall expansion.
The g.243A>G mutation in intron 17 of MUC4 is significantly associated with susceptibility/resistance to ETEC F4ab/ac infection in pigs
Authors: Peng Q.‐L. , Ren J. , Yan X.‐M. , Huang X. , Tang H. , Wang Y.‐Z , Zhang B. , Huang L.‐S. 
Published: June 2007

SummaryUsing a porcine radiation hybrid panel, we assigned the mucin 4 (MUC4) gene to SSC13q41, which harbours the enterotoxigenic Escherichia coli (ETEC) F4ab/ac receptor locus. In addition, we identified two SNPs in intron 17 of MUC4 (DQ124298:g.243A>G and DQ124298:g.334A>G) in the parental population of a White Duroc × Erhualian cross. Association analysis showed that the MUC4 g.243A>G mutation was strongly associated with ETEC F4ab/ac, and especially with F4ac adhesion phenotypes in the White Duroc × Erhualian resource population, indicating that this polymorphism was in a significant linkage disequlibrium with the ETEC F4ab/ac receptor locus. Because of different linkage disequlibrium values between the ETEC F4ab and F4ac adhesion phenotypes and the MUC4 g.243A>G mutation, we argue that the inheritance of F4ab and F4ac receptors might be under the control of two closely linked loci.
Periodontal aspects of restorative dentistry
Authors: RAMFJORD SIGURD P. 
Published: June 2007

SummaryCurrent trends in periodontal aspects of restorative dentistry are: (1) Supragingival placement of margins of restorations. (2) Avoidance of overcontoured restoration, and minimal concern with lack of contour. (3) Search for occlusal stability or self‐limited movement patterns of teeth through precise occlusal adjustment and accurate reconstruction of occlusal anatomy in single restorations. (4) Restricted indications for splinting of mobile teeth. (5) Hemisection with fixed bridges in cases of extensive bifurcation involvement. (6) Restricted indications for replacement of lost molars.The purpose of restorative dentistry is to restore and maintain health and functional comfort of the natural dentition combined with satisfactory aesthetic appearance. Thus, all dental restorations should comply with established requirements for periodontal physiology and health, both with regard to surface and functional characteristics.
Relation between facial morphology and activity of the masticatory muscles
Authors: INGERVALL BENGT , THILANDER BIRGIT 
Published: June 2007

SummaryThe relation between muscle activity and facial morphology was studied in twenty‐five boys and twenty‐seven girls, aged 9–11 years. The activity in the anterior and posterior parts of the temporal muscle, the masseter muscle and the upper lip was recorded bilaterally with the mandible in postural position and during chewing, swallowing and maximal bite. The electromyograms were analysed in respect of maximal mean voltage amplitude and the duration of muscle activity. Facial morphology was studied with the aid of profile roentgenograms and model analysis. The activity in postural position was found to be greater in the posterior than in the anterior part of the temporal muscle. The average mean voltage amplitude in the temporal and masseter muscles was greatest during maximal bite, smaller during chewing and smallest during swallowing. In the orbicularis oris muscle the activity was greater during the opening phase of the chewing cycle than during the closing phase.In postural position the activity in the anterior and posterior parts of the temporal muscle were positively correlated. The amplitudes in the anterior and posterior parts of the temporal muscle and in the masseter muscle were positively correlated during chewing, swallowing and maximal bite. The amplitudes in these muscles during chewing were positively correlated with those in the same muscles during maximal bite. During swallowing the amplitude in the upper lip was negatively correlated with that in the anterior part of the temporal muscle.The clearest correlations between muscle activity and facial morphology were found during chewing and maximal bite. During these functions the amplitudes in the temporal and masseter muscles were large in cases with a tendency to parallelism between the jaws bases and between the mandibular occlusal line and the mandibular line. These cases with considerable muscle activity are characterized by rectangular shape of the face in profile and small lower face height.
A new method to determine the dimensional behaviour of dental amalgam
Authors: VRIJHOEF M. M. A. , SPANAUF A. J. , DRIESSENS F. C. M. 
Published: June 2007

SummaryLiterature data was analysed to find the factors which might influence the results of the determination of the dimensional change of dental amalgams during setting, by methods analogous to the test described in ADA Specification no. 1. Included in the paper is a discussion of the different aspects of adaptation of an amalgam restoration to the wall of a cavity. The conclusion was that the ADA dimensional change test is unsatisfactory because its outcome is highly dependent on experimental variables. The experimental problems involved in this test appeared to be unsolvable. A new method to obtain the dimensional change during setting in a clinically relevant way was proposed. This method consists in the determination of the dimensions of preferably cylindrical specimens after setting of the amalgam in a mould.The results are described of the direct determination of the dimensional change by measurement of the diameter of set cylindrical specimens prepared by clinically simulated packing techniques. The dimensional change also was computed from independent measurements of the adaptation. The correlation between the two series of results was determined and compared with the theoretical prediction.A good correlation between both sets of data was established.
Stresses and deflections in the floor of model cavity preparations
Authors: FARAH JEAN W. , HOOD JAMES A. A. , CRAIG ROBERT G. 
Published: June 2007

SummaryIn this study the finite element method was used in conjunction with an axisymmetric model of an idealized first molar to determine the stresses, as well as deflections in the floor of a cylindrical cavity preparation as caused by condensers of various sizes.It was found that for the 0·25 mm thickness of dentine, the 2 mm condenser and a 2 kg load, a tensile stress of approximately 70 MN/m2 was obtained near the centre of the preparation. Under the same load and a 4 mm condenser a tensile stress of only 42 MN/m2 was obtained. Bowen & Rodriguez (1962) and Lehman (1967) reported that the tensile strength of dentine was in the order of 51.7 MN/m2 and 41.5 MN/m2 respectively. Thus it was demonstrated that for certain combinations of load, condenser size, and cavity dimensions, the tensile strength of the dentine in the cavity floor could be exceeded and failure of the cavity floor could ensue.
Factors influencing the determination of the occlusal vertical dimension by means of a screw jack
Authors: TRYDE GERD , McMILLAN D. R. , STOLTZE K. , MORIMOTO T. , SPANNER O. , BRILL N. 
Published: June 2007

SummaryThe screw jack method has recently been introduced as a new approach to assessing the occlusal height in edentulous patients. Its use is psycho‐physical in nature, and is supposed to rely on neurophysiological mechanisms. Its accuracy has been tested, and it was found to be sensitive to two factors; (i) interactions between dentist and patient, and (ii) to time. More clinical and neurophysiological research is required to refine the method, before it can be expected to replace generally accepted methods.
Age changes in the two‐point discrimination threshold in human oral mucosa
Authors: BRILL NIELS , TRYDE GERD , EDWARDS CAROLINE , THOMAS HELEN 
Published: June 2007

SummaryFifty young and fifty elderly subjects were tested by a two‐point discrimination method applying an aesthesiometer to the mucous membrane of lips, cheeks and tongue. Two changes characteristic of ageing were disclosed: (1) higher threshold values were found in the older age group concomitant with (2) a greater range of variation in these values. The importance of the perception of tactile stimuli from the structures tested is discussed in relation to adaptation to full dentures. It is suggested that signals arising from lips, cheeks and tongue assist the process of adaptation, whereas signals from the denture foundation can, on occasion, prevent adaptation.
Adjustment visits following provision of complete dentures
Authors: MÄKILÄ EINO 
Published: June 2007

SummaryThe adjustment visits of 259 patients, fitted with complete dentures for one or both jaws, at a denture clinic for the poorer social classes were studied. Only 44 % made one or several adjustment visits. The mean number of their visits was 1.28 and that of all the patients 0.56. The older age group contained a larger number of returning patients than the younger (P < 0.05), and so did the group that had not been given written instructions (P < 0.05). Healthy subjects visited the clinic earlier and also more often than the subjects in poor health (P < 0.05). Sex, previous denture experience and the palatal compression used in taking impressions did not affect the return visits. The most frequent causes of the visits were pain produced by the dentures, and retention difficulties.
The experimenter effect on results with oral form recognition tests and with tests measuring oral muscular ability*
Authors: LANDT HORST , AHLIN LARS , LINDQUIST LARS 
Published: June 2007

SummaryIn the introductory part of the present study considerable differences in registrations were found between three different experimenters when an oral form recognition test and an oral muscular‐motor test was applied on ten subjects.In the following part recording differences between six other experimenters were evaluated. An intensive training programme was established and repeated twice with those six experimenters during a test period during which twenty‐eight subjects were tested with the same tests as mentioned above. The results show that in spite of the training programme, uniformity could not be obtained between experimenters.Registration deviations were (1) clearly found for the time results of identifying, (2) less distinctly for registration of subjective judgements of difficulty or for the times of putting together the halves of the test pieces in the test of muscular‐motor ability and (3) not at all at the recording of test piece confusions at the oral form recognition test.It was found that the present forms of the training programme alone were not sufficient to gain uniformity between different experimenters but the suitability of prospective experimenters who are supposed to form a common group should be tested by an evaluation of test results found in a real test situation. Experimenters who are clearly deviating, should be replaced by other ones for the task who are more suitable individuals.The present study thus emphasizes the previously observed difficulties when clinical observations made by different persons are to be compared.
Adaptation of silicate and Adaptic to the margins of cavities
Authors: SELA M. , SELA J. , ARAD T. , ULMANSKY M. 
Published: June 2007

SummaryThe effects of etching of the enamel, on the adaptation of silicate and Adaptic to the cavity walls was examined with the scanning electron microscope. Replica methods were utilized to ensure that no shrinkage of the filling materials was caused by the vacuum in the instrument. It was shown that following etching of the cavity margins, Adaptic adhered to the enamel with absent, or minimal, fissure formation on one side of the filling, and some on the opposite side. The adaptation of silicate to the margins of the cavities was not improved by etching.
Linear dimensional change during setting of a zinc phosphate cement
Authors: ØILO GUDBRAND 
Published: June 2007

SummaryA method for studying the linear dimensional changes of dental cements during setting has been described. The measurements started 3 min after commencing the mix with specimens placed on a mercury bath. Measurements were performed at 37°C a.nd under various environmental humidity.The specimens were made of a fine grain zinc phosphate cement with high powder/ liquid ratio (3/1: g/ml) and low powder/liquid ratio (2/1: g/ml), and the measurements showed that the cement contracted during setting under both wet and dry conditions.Under wet conditions cements with both high and low powder/liquid ratio showed the same contraction, with 0.43% after 30 min reaching a maximum of 0‐66% after 1 day.Under dry conditions the contraction was more pronounced, and somewhat dependent on the powder/liquid ratio. The cement with the high powder/liquid ratio showed 1.33% contraction after 30 min with a maximum of 3.83% after 7 days, whereas the corresponding values for cement with low powder/liquid ratio were 0.79% and 4.76%.
Cleanser solution effects on denture base resins
Authors: ROSSIWALL B. , NEWESELY H. 
Published: June 2007

SummaryScanning electron microscopic investigations were conducted to determine morphostructural alterations on denture base resin surfaces after immersions in commercially available oxygen liberating denture cleansers. The topography of properly processed denture resins did not show corrosive effects, whereas inconsistent surface characteristics of improperly processed wet‐mix acrylates could suggest less resistance. In spite of thorough rinsing after immersion, deposits were noted on the resins of varying amount, size, and quality according to the cleanser used. A possible clinical relevance of such deposits is yet to be evaluated.
The concept of oral rehabilitation*
Authors: FRANKS A. S. T. 
Published: June 2007

SummaryDentistry must re‐examine its professional obligations towards the patient and consider whether its present basis is too rigidly technical. Oral rehabilitation can be defined in terms of the restoration of function and aesthetics. However, it must include also a philosophy of concern for an oral invalid who may require continued and varied help in the management of his disability. The understanding of this concept requires an analysis of the meaning and impact of an oral disorder on an individual, and the responsibilities of those who have to provide him with guidance. Consideration must be given to the reflections of these principles of care on the teaching of dental students.
Frequency of symptoms of mandibular dysfunction in young Swedish men
Authors: MOLIN CARL , CARLSSON GUNNAR E. , FRILING BO , HEDEGÅRD BJÖRN 
Published: June 2007

SummaryThe occurrence of symptoms of dysfunction of the masticatory system was studied in 253 Swedish men from the region of Stockholm with an average age of 19 years. Besides inquiry by questionnaire regarding subjective symptoms a clinical functional examination of the masticatory apparatus was performed.Fourteen per cent were aware of clicking of the temporomandibular joint and 12% of other symptoms of dysfunction such as difficulties in opening the mouth wide, locking and pain on performance of various movements of the mandible. In the clinical investigation, symptoms of dysfunction were noted in 28 % of those examined, mainly in the form of tenderness to palpation over the temporomandibular joints and of the masticatory musculature as well as difficult, painful and irregular movements of the mandible.Individuals with clinical symptoms of dysfunction of the masticatory system had a higher frequency of other joint and muscle symptoms, clicking of the temporomandibular joint and occlusal disturbances in the form of balancing side interferences, than those without clinical symptoms. Balancing side interferences were the only occlusal disturbance that was significantly correlated with the symptoms of dysfunction (pain on movement and tenderness to palpation).
A long‐term prognosis for the fixed saddle‐bridge
Authors: IZIKOWITZ LENNART 
Published: June 2007

SummaryThis report constitutes a long‐term study of 100 saddle‐bridges applied by the author during the years 1958–1973. The aim of the investigation has been to assess the prognosis for this form of therapy. The probability that a saddle‐bridge will still be functioning completely, without repair, after 5 years is 93 %, and after 10 years (as also after 12 years) 83%. Only 12% of the appliances had been removed 12 years after the application.The risk of defects is about the same during the first 5‐year period after the application as it is during the second and the third 5‐year periods. A comparison between saddle‐bridges applied before and after 1965 shows no demonstrable difference as regards the 5‐year prognosis in spite of modifications with respect to range of indication and therapy.The causes of the defects have been divided into biological and technical. During the first 5‐year period technical defects appear to be in the majority, whereas during the later stages, biological defects predominate. Background factors such as sex, the age of the patient, length of saddle, localization in the jaw do not prove to have any appreciable importance for the prognosis. There is, on the other hand, a significantly better prognosis when the opposing jaw is furnished with the patient's own teeth and/or fixed bridges than with a removable denture.The author points out that from the result of the study, the saddle‐bridge has such a good long‐term prognosis that its range of application for fixed constructions should be considerably extended.
Disturbances in the contraction and co‐ordination pattern of the masticatory muscles due to dental restorations
Authors: KLOPROGGE M. J. G. M. , van GRIETHUYSEN A. M. 
Published: June 2007

SummaryRecent Swedish publications report that a large number of patients suffer from the mandibular dysfunction syndrome. Some theories assume that this syndrome is the result of a disturbance in blood flow through the maxillary artery.The present authors suggest, that the syndrome is caused by a disturbance in the pattern of contraction of the masticatory muscles. This hypothesis is based on the assumption that the human periodontal membrane contains mechanoreceptors which are able to exert reflex control over the pattern of contraction of the muscles during chewing.If the pattern of stimulation of these receptors is modified following dental restoration, then this could result in a disturbance of the neuromuscular pattern of the masticatory apparatus. In order to test this hypothesis, an electromyographic study was carried out in three volunteers and eight patients. The results of this study support the view that there are receptors in the human periodontal membrane which are able to control the pattern of contraction of the masticatory muscles.The hypothesis that the mandibular dysfunction syndrome is the result of a disturbance in the pattern of contraction of these muscles is pursued further in the discussion.