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PURPOSE: The purpose of the study was to develop a finite element model of the human mandible and to compare the functional deformation predicted by the model with that detected clinically. MATERIALS AND METHODS: Three patterns of mandibular deformation (medial convergence, corporal rotation and dorso-ventral shear) were studied clinically in 12 subjects using custom-fabricated displacement transducers mounted on endosseous implants in the premolar region. The mandibular arches of 12 patients with dental implants were modeled using finite element techniques based on computerized tomographic (CT) scan images of the jaw. RESULTS: The finite element model was found to closely replicate the patterns of observed mandibular deformation. Differences between the predicted and measured deformation values were expressed as a percentage of the measured value and ranged between 0.0% and 22.2%. Medial convergence ranged between 14.4 and 58.4 pm. Dorso-ventral shear and corporal rotation ranged between 0.4 and 2.7 degrees. CONCLUSIONS: Using the finite element model described in this study, which represents the living human mandible, and clinical testing, there was close agreement between the predicted and measured deformation values. This study provided a high level of confidence in the finite element model and its ability to provide better insight into understanding the complex phenomena of functional mandibular deformation. [ABSTRACT FROM AUTHOR]

Managing coastal wetlands is one of the most promising activities to reduce atmospheric greenhouse gases, and it also contributes to meeting the United Nations Sustainable Development Goals. One of the options is through blue carbon projects, in which mangroves, saltmarshes, and seagrass are managed to increase carbon sequestration and reduce greenhouse gas emissions. However, other tidal wetlands align with the characteristics of blue carbon. These wetlands are called tidal freshwater wetlands in the United States, supratidal wetlands in Australia, transitional forests in Southeast Asia, and estuarine forests in South Africa. They have similar or larger potential for atmospheric carbon sequestration and emission reductions than the currently considered blue carbon ecosystems and have been highly exploited. In the present article, we suggest that all wetlands directly or indirectly influenced by tides should be considered blue carbon. Their protection and restoration through carbon offsets could reduce emissions while providing multiple cobenefits, including biodiversity., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Institute of Biological Sciences.)

Mangrove forests are the dominant vegetation growing on low wooded islands, which occur in the Caribbean, Indian and Pacific Oceans. In the northern Great Barrier Reef, we map remarkable, undocumented mangrove forest extension on 10 low wooded islands in the Howick Group that collectively equates to an area of 667 000 m 2 (66.7 ha). We combine extensive field survey with canopy height models derived from RPA imagery and allometric scaling to quantify above ground biomass in both old (pre-1973) and new (post-1973) forest areas. Forest expansion added approximately 10 233 tonnes of new biomass since the early 1970s. We suggest that such substantial expansion of mangrove forest has occurred within a short time span in response to changing environmental controls. These may include sea-level rise, sediment transport and deposition, cyclone impact and the development of associated reef flat sedimentary landforms including unconsolidated and lithified shingle ridges, which influence reef flat hydrodynamics. Our observations highlight the globally dynamic response of mangrove distribution and forest structure to environmental change and provide timely new estimates from understudied reef island settings.

Several coastal ecosystems-most notably mangroves and tidal marshes-exhibit biogenic feedbacks that are facilitating adjustment to relative sea-level rise (RSLR), including the sequestration of carbon and the trapping of mineral sediment 1 . The stability of reef-top habitats under RSLR is similarly linked to reef-derived sediment accumulation and the vertical accretion of protective coral reefs 2 . The persistence of these ecosystems under high rates of RSLR is contested 3 . Here we show that the probability of vertical adjustment to RSLR inferred from palaeo-stratigraphic observations aligns with contemporary in situ survey measurements. A deficit between tidal marsh and mangrove adjustment and RSLR is likely at 4 mm yr -1 and highly likely at 7 mm yr -1 of RSLR. As rates of RSLR exceed 7 mm yr -1 , the probability that reef islands destabilize through increased shoreline erosion and wave over-topping increases. Increased global warming from 1.5 °C to 2.0 °C would double the area of mapped tidal marsh exposed to 4 mm yr -1 of RSLR by between 2080 and 2100. With 3 °C of warming, nearly all the world's mangrove forests and coral reef islands and almost 40% of mapped tidal marshes are estimated to be exposed to RSLR of at least 7 mm yr -1 . Meeting the Paris agreement targets would minimize disruption to coastal ecosystems., (© 2023. The Author(s).)

Many marine ecosystems have the capacity for long-term storage of organic carbon (C) in what are termed "blue carbon" systems. While blue carbon systems (saltmarsh, mangrove, and seagrass) are efficient at long-term sequestration of organic carbon (C), much of their sequestered C may originate from other (allochthonous) habitats. Macroalgae, due to their high rates of production, fragmentation, and ability to be transported, would also appear to be able to make a significant contribution as C donors to blue C habitats. In order to assess the stability of macroalgal tissues and their likely contribution to long-term pools of C, we applied thermogravimetric analysis (TGA) to 14 taxa of marine macroalgae and coastal vascular plants. We assessed the structural complexity of multiple lineages of plant and tissue types with differing cell wall structures and found that decomposition dynamics varied significantly according to differences in cell wall structure and composition among taxonomic groups and tissue function (photosynthetic vs. attachment). Vascular plant tissues generally exhibited greater stability with a greater proportion of mass loss at temperatures > 300 degrees C (peak mass loss -320 degrees C) than macroalgae (peak mass loss between 175-300 degrees C), consistent with the lignocellulose matrix of vascular plants. Greater variation in thermogravimetric signatures within and among macroalgal taxa, relative to vascular plants, was also consistent with the diversity of cell wall structure and composition among groups. Significant degradation above 600 degrees C for some macroalgae, as well as some belowground seagrass tissues, is likely due to the presence of taxon-specific compounds. The results of this study highlight the importance of the lignocellulose matrix to the stability of vascular plant sources and the potentially significant role of refractory, taxon-specific compounds (carbonates, long-chain lipids, alginates, xylans, and sulfated polysaccharides) from macroalgae and seagrasses for their long-term sedimentary C storage. This study shows that marine macroalgae do contain refractory compounds and thus may be more valuable to long-term carbon sequestration than we previously have considered.

Stable isotope techniques in food web studies often focus on organic carbon in food sources which are subsequently assimilated in the tissue of consumer organisms through diet. The presence of non-dietary carbonates in bulk samples can affect their δ(13)C values, altering how their results are interpreted. Acidification of samples is a common practice to eliminate any inorganic carbon present prior to analysis. We examined the effects of pre-analysis acidification on two size fractions of sediment organic matter (SOM) from marine and freshwater wetlands and pure muscle tissue of a common freshwater invertebrate (Cherax destructor). The elemental content and isotopic ratios of carbon and nitrogen were compared between paired samples of acidified and control treatments. Our results showed that acidification does not affect the elemental or isotopic values of freshwater SOM. In the marine environment acidification depleted the δ(13)C and δ(15)N values of the fine fraction of saltmarsh and δ(15)N values of mangrove fine SOM. Whilst acidification did not change the elemental content of invertebrate muscle tissue, the δ(13)C and δ(15)N values were affected. We recommend to researchers considering using acidification techniques on material prepared for stable isotope analysis that a formal assessment of the effect of acidification on their particular sample type should be undertaken. Further detailed investigation to understand the impact of acidification on elemental and isotopic values of organic matter and muscular tissues is required., (Copyright © 2010 John Wiley & Sons, Ltd.)

The purpose of this study was to mathematically validate and clinically verify a finite element model (FEM) of the human mandible and to compare the functional deformation predicted by the model with that detected clinically. Mandibular surface strain, using 11 single strain gauges, and medial convergence (MC), using a custom-fabricated linear variable differential transformer (LVDT), were recorded in a dried human jaw. The mandible was treated with two endosseous implants, placed bilaterally in the premolar area, and mounted in a rig that simulated natural function of the jaw. Measurements were made in real time using a multichannel analogue/digital converter and a personal computer for data storage and analysis. A FEM of the mandible was constructed, using commercially available finite element software, based on CT scan images of the jaw. MC was predicted as the linear change in the orientation of the two implants in the horizontal plane. Predicted and measured values of MC ranged between 60 and 109 microm. The differences between the measured and predicted strain magnitudes were expressed as absolute percentages of the measured values and ranged between 3 and 18%. The limits of agreement between the predicted and measured strain values, as suggested by Bland and Altman (Lancet 1986; 1:307-310), were small enough for the predictions from the FEM to be considered clinically acceptable. The good agreement between the predicted and measured strain values indicates the accuracy of the present FEM. Finite element analysis is a powerful technique that provides a better insight into understanding the complex phenomena of mandibular functional deformation., ((c) 2006 Wiley Periodicals, Inc.)

Purpose: The purpose of this study was to measure corporal approximation, dorsoventral shear, and corporal rotation in edentulous subjects treated with dental implants, during normal mandibular movements., Materials and Methods: Three patterns of jaw deformation (corporal approximation [CA], corporal rotation [CR], and dorsoventral [DV] shear) were measured using custom-fabricated displacement transducers in 12 edentulous subjects who had been treated with dental implants. Measurements were made in real time using a multichannel analogue/digital converter and a personal computer for data storage and analysis. Corporal approximation was measured as the linear change in the orientation of the 2 implants in the horizontal plane. Corporal rotation was recorded as a relative rotation of the right and left mandibular bodies projected into the frontal plane, and dorsoventral shear as the relative rotation of the 2 implants projected onto the median sagittal plane., Results: All 3 patterns of mandibular deformation occurred concurrently and immediately on commencement of jaw movement. Different jaw movements produced different patterns of mandibular deformation. The highest values of jaw deformation were recorded during protrusion. CA ranged between 11.0 microm and 57.8 microm. Corporal rotation and DV shear ranged between 0.4 degrees and 2.8 degrees ., Conclusion: This clinical study shows and measures 3 different and concurrent patterns of jaw deformation, during normal mandibular movements, using custom fabricated displacement transducers. The transducers may have a potential for routine clinical applications.

Purpose: The purpose of this study was to measure medial convergence, dorsoventral shear, and corporal rotation in the human mandible., Materials and Methods: Measurements were made using custom-fabricated strain gauge displacement transducers in 6 edentulous subjects who had been treated with mandibular endosseous dental implants. These were mounted on the most distal of the mandibular implants on each side, and measurements were made in real time using a multichannel analogue/digital converter and a personal computer for data storage and analysis. Measurements were made while the implants were loaded, and the subjects opened and closed their mouths and made lateral mandibular excursions. Medial convergence was measured as a linear change at the site of the most distal implant. Dorsoventral shear was expressed as a relative rotation of the right and left mandibular bodies projected onto the median sagittal plane, and corporal rotation was expressed as the relative rotation of the most distal implant., Results: Jaw deformation was found to occur immediately on opening and was related to closing forces and jaw position. Medial convergence of up to 41 microns was observed, with values for corporal rotation of up to 6 degrees and dorsoventral shear of up to 19 degrees., Conclusion: The study demonstrated clinically for the first time 3 different and simultaneous patterns of functional mandibular deformation.

Forces to which individual implant units are subjected when an implant-stabilised mandibular over-denture is loaded have been measured using a carbon-fibre reinforced epoxy resin replica of an edentulous mandible mounted in a loading rig which simulated physiological conditions. Three different retentive designs were used; ball attachments, a fixed-fixed bar cranked anteriorly, and a similar design with posterior cantilevers. Forces exerted on the implants were measured using resistance strain gauges mounted on their trans-mucosal abutments and the dentures were loaded at individual tooth positions with a strain gauge beam. Ball attachments were associated with the lowest detected forces on the abutments. It is concluded that variations in superstructure design affect the forces transmitted by implants stabilising a complete mandibular over-denture, when the mandible is suspended and loaded in a physiological manner.

The present study compared the fit of acrylic resin bases subjected to two curing cycles in a water-bath or in a microwave oven. Resin bases were processed on duplicate stone casts prepared from a cobalt chromium master die. Ten bases, composed of conventional polymethylmethacrylate, were cured in a water-bath for 7 h at 70 degrees C and 3 h at 100 degrees C, and a further 10 cured in a domestic microwave oven at 65 W for 25 min. Ten bases composed of polymethylmethacrylate modified by means of a chemical activator were cured at 100 degrees C in a water-bath for 20 min. All bases were then subjected to a second curing cycle following addition of new acrylic resin to the alveolar ridge areas. Following each curing cycle the fit of the posterior border of each base was evaluated. A silicone impression material was used to form indices between the bases and the master die, these were then invested in stone and sectioned to allow cross-sectional measurement by means of an eyepiece micrometer. A one-way analysis of variance and unpaired Student's t tests were employed to compare the differences in distortion of the three groups. The differences in distortion between the first and second curing cycles were significant for all curing methods (P less than 0.001). However, microwave curing caused significantly less distortion of the denture base than short water-bath curing, especially in the centre of the palate (P less than 0.001).