90 research outputs found

    Accommodation of penetrative strain during deformation above a ductile décollement

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    The accommodation of shortening by penetrative strain is widely considered as an important process during contraction, but the distribution and magnitude of penetrative strain in a contractional system with a ductile décollement are not well understood. Penetrative strain constitutes the proportion of the total shortening across an orogen that is not accommodated by the development of macroscale structures, such as folds and thrusts. In order to create a framework for understanding penetrative strain in a brittle system above a ductile décollement, eight analog models, each with the same initial configuration, were shortened to different amounts in a deformation apparatus. Models consisted of a silicon polymer base layer overlain by three fine-grained sand layers. A grid was imprinted on the surface to track penetra- tive strain during shortening. As the model was shortened, a series of box fold structures developed, with a zone of penetrative strain in the foreland. Penetrative strain in the foreland decreases away from the fold belt. Restoration of the model layers to the horizontal indicates that penetrative strain accounts for 90.5%-30.8% of total shortening in a brittle system with a ductile décollement, compared to 45.2%–3.6% within a totally brittle system. Analog model geometries were consistent with the deformation styles observed in salt-floored systems, such as the Swiss Jura. Penetrative strain has not been accounted for in previous studies of salt-floored regions and estimates of this type could help resolve concerns of missing shortening highlighted by global positioning system data

    Late Cretaceous to Recent Deformation Related to Inherited Structures and Subsequent Compression within the Persian Gulf: A 2D Seismic Case Study

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    The Persian Gulf is part of an asymmetric foreland basin related to the Zagros Orogen. Few published studies of this basin and associated onshore areas include seismic reflection data. We present a seismic-stratigraphic interpretation based on marine 2D seismic data, which reveals the presence of two types of compressional structures within the basin: (1) faulted domes related to salt movement and the offshore trace of a NNE–SSW-trending dextral basement fault (the Kazerun Fault); (2) long-wavelength (16 km), low-amplitude (60 ms two-way travel time) folds relating to the advancing deformation front associated with the orogen. Thinning of age-constrained stratal units across structures related to the offshore trace of the Kazerun Fault implies a distinct pulse of uplift on this fault during the Maastrichtian. The geometry of growth strata across other intra-basin structures suggests a second, later stage of deformation, which began in the Middle Miocene. Thickening and folding of post-Middle Miocene stratal units towards the NE (i.e. towards the Zagros Orogen) is interpreted to reflect rapid loading, subsidence and compression related to southwestwards advance of the orogen. The results of this study have implications for the interaction between pre-existing structures and later compressional events both within the Persian Gulf and elsewhere

    Late Cretaceous to Recent Deformation Related to Inherited Structures and Subsequent Compression within the Persian Gulf: A 2D Seismic Case Study

    Get PDF
    The Persian Gulf is part of an asymmetric foreland basin related to the Zagros Orogen. Few published studies of this basin and associated onshore areas include seismic reflection data. We present a seismic-stratigraphic interpretation based on marine 2D seismic data, which reveals the presence of two types of compressional structures within the basin: (1) faulted domes related to salt movement and the offshore trace of a NNE–SSW-trending dextral basement fault (the Kazerun Fault); (2) long-wavelength (16 km), low-amplitude (60 ms two-way travel time) folds relating to the advancing deformation front associated with the orogen. Thinning of age-constrained stratal units across structures related to the offshore trace of the Kazerun Fault implies a distinct pulse of uplift on this fault during the Maastrichtian. The geometry of growth strata across other intra-basin structures suggests a second, later stage of deformation, which began in the Middle Miocene. Thickening and folding of post-Middle Miocene stratal units towards the NE (i.e. towards the Zagros Orogen) is interpreted to reflect rapid loading, subsidence and compression related to southwestwards advance of the orogen. The results of this study have implications for the interaction between pre-existing structures and later compressional events both within the Persian Gulf and elsewhere

    Porphyromonas gingivalis oral infection exacerbates the development and severity of collagen-induced arthritis

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    Abstract Introduction Clinical studies suggest a direct influence of periodontal disease (PD) on serum inflammatory markers and disease assessment of patients with established rheumatoid arthritis (RA). However, the influence of PD on arthritis development remains unclear. This investigation was undertaken to determine the contribution of chronic PD to immune activation and development of joint inflammation using the collagen-induced arthritis (CIA) model. Methods DBA1/J mice orally infected with Porphyromonas gingivalis were administered with collagen II (CII) emulsified in complete Freund’s adjuvant (CFA) or incomplete Freund’s adjuvant (IFA) to induce arthritis. Arthritis development was assessed by visual scoring of paw swelling, caliper measurement of the paws, mRNA expression, paw micro-computed tomography (micro-CT) analysis, histology, and tartrate resistant acid phosphatase for osteoclast detection (TRAP)-positive immunohistochemistry. Serum and reactivated splenocytes were evaluated for cytokine expression. Results Mice induced for PD and/or arthritis developed periodontal disease, shown by decreased alveolar bone and alteration of mRNA expression in gingival tissues and submandibular lymph nodes compared to vehicle. P. gingivalis oral infection increased paw swelling and osteoclast numbers in mice immunized with CFA/CII. Arthritis incidence and severity were increased by P. gingivalis in mice that received IFA/CII immunizations. Increased synovitis, bone erosions, and osteoclast numbers in the paws were observed following IFA/CII immunizations in mice infected with P gingivalis. Furthermore, cytokine analysis showed a trend toward increased serum Th17/Th1 ratios when P. gingivalis infection was present in mice receiving either CFA/CII or IFA/CII immunizations. Significant cytokine increases induced by P. gingivalis oral infection were mostly associated to Th17-related cytokines of reactivated splenic cells, including IL-1β, IL-6, and IL-22 in the CFA/CII group and IL-1β, tumor necrosis factor-α, transforming growth factor-β, IL-6 and IL-23 in the IFA/CII group. Conclusions Chronic P. gingivalis oral infection prior to arthritis induction increases the immune system activation favoring Th17 cell responses, and ultimately accelerating arthritis development. These results suggest that chronic oral infection may influence RA development mainly through activation of Th17-related pathways.http://deepblue.lib.umich.edu/bitstream/2027.42/112639/1/13075_2013_Article_4062.pd

    Holistic Dwelling Energy Assessment Protocol for Mine-water District Heat Network

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    UK buildings and energy infrastructures are heavily dependent on natural gas, and a large proportion is used for domestic space heating; but 50% is imported. Improving energy security and reducing carbon emissions are major government drivers for reducing gas dependency. So, there needs to be a wholesale shift in the energy provision to householders without impacting on thermal comfort levels, convenience or cost of supply. Electrical powered heat pumps are seen as a potential alternative system for heating new dwellings, but will they work in dwellings built prior to 1919? This paper investigates the energy demand of pre-1919 dwellings in Wales, UK as part of a feasibility study to extract water from disused coal mines to supply a district heat network. A holistic surveying protocol providing a more accurate/realistic assessment of total household heat demand is considered. The protocol’s techniques include condition surveys, air permeability and thermography tests, and heat loss calculations are discussed. The results were used to predict future (beyond 2019) heat demand after potential retrofit improvements, thereby informing the size of heat pumps required. The findings show estimated heat demand to be in close correlation to household energy bills, and that the use of heat pumps in pre-1919 dwellings is viable, provided sufficient improvement to thermal performance is possible

    Loss-of-function mutations in the C9ORF72 mouse ortholog cause fatal autoimmune disease.

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    C9ORF72 mutations are found in a significant fraction of patients suffering from amyotrophic lateral sclerosis and frontotemporal dementia, yet the function of the C9ORF72 gene product remains poorly understood. We show that mice harboring loss-of-function mutations in the ortholog of C9ORF72 develop splenomegaly, neutrophilia, thrombocytopenia, increased expression of inflammatory cytokines, and severe autoimmunity, ultimately leading to a high mortality rate. Transplantation of mutant mouse bone marrow into wild-type recipients was sufficient to recapitulate the phenotypes observed in the mutant animals, including autoimmunity and premature mortality. Reciprocally, transplantation of wild-type mouse bone marrow into mutant mice improved their phenotype. We conclude that C9ORF72 serves an important function within the hematopoietic system to restrict inflammation and the development of autoimmunity

    Loss of mouse Stmn2 function causes motor neuropathy

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    Amyotrophic lateral sclerosis (ALS) is characterized by motor neuron degeneration accompanied by aberrant accumulation and loss of function of the RNA-binding protein TDP43. Thus far, it remains unresolved to what extent TDP43 loss of function directly contributes to motor system dysfunction. Here, we employed gene editing to find whether the mouse ortholog of the TDP43-regulated gene STMN2 has an important function in maintaining the motor system. Both mosaic founders and homozygous loss-of-function Stmn2 mice exhibited neuromuscular junction denervation and fragmentation, resulting in muscle atrophy and impaired motor behavior, accompanied by an imbalance in neuronal microtubule dynamics in the spinal cord. The introduction of human STMN2 through BAC transgenesis was sufficient to rescue the motor phenotypes observed in Stmn2 mutant mice. Collectively, our results demonstrate that disrupting the ortholog of a single TDP43-regulated RNA is sufficient to cause substantial motor dysfunction, indicating that disruption of TDP43 function is likely a contributor to ALS

    Porphyromonas gingivalis oral infection exacerbates the development and severity of collagen-induced arthritis

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    Abstract Introduction: Clinical studies suggest a direct influence of periodontal disease (PD) on serum inflammatory markers and disease assessment of patients with established rheumatoid arthritis (RA). However, the influence of PD on arthritis development remains unclear. This investigation was undertaken to determine the contribution of chronic PD to immune activation and development of joint inflammation using the collagen-induced arthritis (CIA) model. Methods: DBA1/J mice orally infected with Porphyromonas gingivalis were administered with collagen II (CII) emulsified in complete Freund’s adjuvant (CFA) or incomplete Freund’s adjuvant (IFA) to induce arthritis. Arthritis development was assessed by visual scoring of paw swelling, caliper measurement of the paws, mRNA expression, paw micro-computed tomography (micro-CT) analysis, histology, and tartrate resistant acid phosphatase for osteoclast detection (TRAP)-positive immunohistochemistry. Serum and reactivated splenocytes were evaluated for cytokine expression. Results: Mice induced for PD and/or arthritis developed periodontal disease, shown by decreased alveolar bone and alteration of mRNA expression in gingival tissues and submandibular lymph nodes compared to vehicle. P. gingivalis oral infection increased paw swelling and osteoclast numbers in mice immunized with CFA/CII. Arthritis incidence and severity were increased by P. gingivalis in mice that received IFA/CII immunizations. Increased synovitis, bone erosions, and osteoclast numbers in the paws were observed following IFA/CII immunizations in mice infected with P gingivalis. Furthermore, cytokine analysis showed a trend toward increased serum Th17/Th1 ratios when P. gingivalis infection was present in mice receiving either CFA/CII or IFA/CII immunizations. Significant cytokine increases induced by P. gingivalis oral infection were mostly associated to Th17-related cytokines of reactivated splenic cells, including IL-1β, IL-6, and IL-22 in the CFA/CII group and IL-1β, tumor necrosis factor-α, transforming growth factor-β, IL-6 and IL-23 in the IFA/CII group. Conclusions: Chronic P. gingivalis oral infection prior to arthritis induction increases the immune system activation favoring Th17 cell responses, and ultimately accelerating arthritis development. These results suggest that chronic oral infection may influence RA development mainly through activation of Th17-related pathways
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