135 research outputs found

    Distribution and growth styles of isolated carbonate platforms as a function of fault propagation

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    Fault control on the position and distribution of isolated carbonate platforms is investigated in Northwest Australia using high-quality 3D seismic and borehole data from the Bonaparte Basin. Specifically, we address the relationship between carbonate productivity and fault growth so as to understand what are the primary controls on the growth of isolated carbonate platforms. Throw-depth (T-Z) and throw-distance (T-D) profiles for normal faults suggest they formed fault segments that were linked at different times in the study area. This caused differential vertical movements; some of the normal faults propagated to the surface, while others have upper tips that are 19–530 ms two-way-time below the sea floor, with the largest throw values comprising faults underneath isolated carbonate platforms. As a result, four distinct zones correlate with variable geometries and sizes of carbonate platforms, which are a function of the topographic relief generated by underlying propagating faults. Some relay ramps form the preferred location for the initiation and development of carbonate platforms, together with adjacent structural highs. Due to the complex effect of fault propagation to the palaeo-seafloor, and soft-linkage through relay ramps, three distinct ICP types are proposed: (1) in the first type, fault throw is larger than carbonate productivity; (2) the second type considers fault throw to be equal or less than carbonate productivity; and (3) in the third type, fault throw post-dates the growth of the carbonate platform(s). The analysis of fault propagation vs. carbonate platform growth shown here is important, as the three ICP types proposed, potentially correlate with variable fracture densities and distributions within the carbonate platforms. Based on our results, types 2 and 3 above enhance fracture- and fault-dominated porosity and permeability to a greater degree, making them favourable targets for hydrocarbon exploration

    Response of elastic/viscoelastic layers on an elastic half-space in rolling contacts:Towards a new modeling approach for elastohydrodynamic lubrication

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    The 3D quasi-static contact problem of a rigid sphere rolling on an elastic half-space covered by a thin viscoelastic/elastic layer is studied as representative of soft layered contacts in engineering, physics, and biomedical applications, as well as for its potential merit to model Elasto-Hydrodynamically Lubricated (EHL) contacts in specific EHL film behavior suggested in earlier research. The viscoelastic layer behavior is modeled with a standard linear solid (SLS) model with a single relaxation time. Two approaches are used, the foundation (Winkler) reduced model assuming unidirectional stress–strain behavior normal to the surface only and the Papkovich–Neuber potential model which, based on the complete Navier–Cauchy equations, accounts for non-local support and bending effects. The models are validated against literature and compared. Whereas coated/layered contact problem studies mostly consider relatively thick coatings, and results focus on the pressure distribution and the contact area size, in this paper we consider layers with a thickness much smaller than the contact radius, i.e. of the order of a thickness of a conventional EHL film. The details of the layer deformation, pressure profiles and subsurface stresses are presented and interpreted in terms of the underlying physics, in particular the thin layer limit common also in thin fluid layers. It is shown that two dimensionless parameters, the ratio of the elastic modulus between the layer and the substrate and the ratio of the layer thickness to the corresponding Hertz contact width, dominate the systematic response for elastic layered contact problems. And four dimensionless parameters with two extras, the Deborah number based on the Hertz contact width and the ratio of the two elastic limits of the SLS viscoelastic material, are needed and analyzed for viscoelastic layered contacts. The results presented provide a good framework for the understanding and interpretation of the effects of viscoelastic layers on the deformation and pressure distribution of contact problems. Finally, the capability of actually modeling EHL film behavior via a viscoelastic layer suggested by van Emden et al. (2017) is discussed.</p

    Participatory Observatories to Connect Multifunctional Landscapes, Link Smallholder Farmers, and Collectively Diversify Income

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    Cattle ranching was introduced to Baja California, Mexico (semiarid and arid climates) by the Spaniards, who brought the animals and the techniques. One important activity was moving livestock from the mountains (forests and few kinds of grass) to the coast crossing poor shrublands known as chaparrals. Fire was a common practice to promote grass growth and pastoralists could move through the land freely. Pastoralism became a common practice when English workers built the Ensenada port and became ranching landowners. They followed the practice of livestock movement through the exorreic watersheds. Native Indians, as well as other Mexicans known as ejidatarios, who had access to communal land, and wealthy livestock managers learned the same transhumance practices. They followed them until recently when privatizing the land began fragmenting the rangeland by installing fences; besides insecure places emerged due to illegal crop production. The Guadalupe watershed in Baja California is an interesting place to study rangelands as dynamic socio-ecological systems driven by institutional changes. Its land-use history has provoked interesting questions oriented to enlighten the future of livestock and rangeland management. This talk deals with the project of a citizen\u27s observatory where results from good local land and water management practices are being compiled and presented in a portal for its out-reach. The internet site will also make available scientific papers translated into infographics to make high-quality information accessible. Before and after special techniques like keyline design, holistic management, and other locally adapted techniques are being measured by ranchers and students as a citizen science program. We think that co-monitoring and improving data availability will facilitate local decision-making and deal with the multifunctionality of future rangelands in a better way

    Stevens-Johnson syndrome and toxic epidermal necrolysis: a review

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    Stevens Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are considered a single entity with variability in the extent of the lesions, characterized by erythema multiforme that may involve mucosa. Severe cutaneous reactions secondary to medications are classified according to the area of epidermal detachment. The activation of cytotoxic T cells and macrophages is mediated mainly by IL-2 and interferon gamma secreted by Th1 lymphocytes, and the activation of eosinophils and B lymphocytes in IgE is mediated by secreted IL-4, IL-5, IL-10 and IL13 by B lymphocytes. The topography of SJS is predominantly central, affecting the trunk and sometimes a generalized dissemination is shown that affects a body surface area of less than 10%, characterized by irregular violaceous erythematous macules of target shooting, which can form confluent blisters. TEN is characterized by a skin detachment greater than 30% of the body surface, whose predominant lesion is diffuse erythema with individual macules, which give rise to detachment surfaces greater than 5 cm. The treatment is symptomatic, nonspecific, and aimed at avoiding complications, carried out in specialized intensive care units, due to ignorance of the pathogenesis. Integral management with different therapeutic alternatives can represent a crucial part in the multisystemic management of SJS and TEN

    Use of rivaroxaban and acetylsalicylic acid as a combined treatment for peripheral arterial disease in Central Military Hospital

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    Background: The objective of this research was to evaluate the behavior of 3 risk indicators for peripheral arterial disease in patients under oral treatment with rivaroxaban 2.5 mg every 12 hours plus, acetylsalicylic acid 100 mg every 24 hours. It was hypothesized that the oral combination of rivaroxaban and acetylsalicylic acid presents a therapeutic advantage over other treatments.Methods: A prospective longitudinal and non-randomized study of a single center was performed. 59 patients with peripheral arterial disease were included and treated with acetylsalicylic acid + rivaroxaban. Peak systolic velocity, ankle-brachial index and C reactive protein index were evaluated.Results: Significant changes were found at month 1 and 3 of follow-up in maximum systolic velocity, ankle-arm index and C-reactive protein index. The baseline peak systolic velocity (PSV) in the anterior tibial artery had significant differences after one month of treatment (p=0.001) and after 3 months (p=0.001). The baseline PSV in the posterior tibial artery had significant differences compared to the values found at the month of treatment (p=0.001) and 3 months (p=0.001). In the ankle-brachial index a baseline median of 0.790 was found, one month after the treatment of 0.795 (p=0.147) and 3 months after 0.800 (p=0.019). The mean baseline C-reactive protein obtained was 73.142 mg/l, at one month 87.233 mg/l (p=0.001) and at 3 months at 79.009 mg/l (p=0.294) with a standard deviation of 67.18, 74.78 and 69.69 respectively.Conclusions: The combined use of acetylsalicylic acid and rivaroxaban allows a clinical improvement in patients with peripheral arterial disease

    Antebrachial microvascular flap for reconstruction of the pelvic limb: case report

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    Complex defects in the soft tissues of the foot and ankle caused by high-energy trauma, infection, cancer or diabetes require rapid and effective treatment which decreases the risk of infection, bone healing time, hospital stay and number total of surgical approaches. Authors report a clinical case of a 23-year-old female patient who suffers high-energy trauma due to a motorcycle accident which causes exposure of the distal third of the tibia, loss of the tibial joint face, and loss of tissue throughout the region of the malleolus medial of the right pelvic extremity. Tissue transfer to the pelvic limb is performed using left contralateral radial antebrachial free flap as donor area. This case report aims to emphasize the key aspects of the high energy trauma approach by using microvascular flaps, as well as the satisfactory evolution of the patient that directly affects the prognosis for life and function

    Nutritional characteristics of different types of eggs

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    Objective: To analyze 5 types of poultry eggs (chicken, turkey, ostrich, duck and quail) to compare their nutritional characteristics and sensory properties. Design/ Methodology/ Approach: A physical analysis was performed: weight of the entire egg (weight and proportion of the albumin, yolk and shell) length and width of the entire egg, shape index, shell color, and yolk color, nutritional (determination of raw fat, protein, dry matter and ashes) and in sensory adaptation (measured through hedonic testing of adaptability through the arrangement of nine points to an individualized quantity of 97). Different types of egg used: chicken, turkey, ostrich, duck and quail. Results: The egg containing the most amount of protein was that of the duck (13.02 ± 0.46 %), while the sample containing the lowest result was that of the ostrich (9.47 ± 0.27 %). The type of egg that contained the fattest level was the duck (10.31 ± 0.75 %); on the other hand, the type of egg that demonstrated the least amount of fat was that of the chicken egg (8.28 ± 0.39 %). Results/ Findings/ Conclusion: Even though some physical differences exist in all types of eggs, they are similar and there is minimal variation in terms of their nutritional value. Therefore, these different types of eggs can be applied for consumption as substitutes for chicken eggs and as an alternative source of protein. Limitations of the study/ Implications: Lack of previous research in regard to comparisons of the types of analyzed eggs

    The Candida albicans Ku70 Modulates Telomere Length and Structure by Regulating Both Telomerase and Recombination

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    The heterodimeric Ku complex has been shown to participate in DNA repair and telomere regulation in a variety of organisms. Here we report a detailed characterization of the function of Ku70 in the diploid fungal pathogen Candida albicans. Both ku70 heterozygous and homozygous deletion mutants have a wild-type colony and cellular morphology, and are not sensitive to MMS or UV light. Interestingly, we observed complex effects of KU70 gene dosage on telomere lengths, with the KU70/ku70 heterozygotes exhibiting slightly shorter telomeres, and the ku70 null strain exhibiting long and heterogeneous telomeres. Analysis of combination mutants suggests that the telomere elongation in the ku70 null mutant is due mostly to unregulated telomerase action. In addition, elevated levels of extrachromosomal telomeric circles were detected in the null mutant, consistent with activation of aberrant telomeric recombination. Altogether, our observations point to multiple mechanisms of the Ku complex in telomerase regulation and telomere protection in C. albicans, and reveal interesting similarities and differences in the mechanisms of the Ku complex in disparate systems

    Effect of Ku80 Deficiency on Mutation Frequencies and Spectra at a LacZ Reporter Locus in Mouse Tissues and Cells

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    Non-homologous end joining (NHEJ) is thought to be an important mechanism for preventing the adverse effects of DNA double strand breaks (DSBs) and its absence has been associated with premature aging. To investigate the effect of inactivated NHEJ on spontaneous mutation frequencies and spectra in vivo and in cultured cells, we crossed a Ku80-deficient mouse with mice harboring a lacZ-plasmid-based mutation reporter. We analyzed various organs and tissues, as well as cultured embryonic fibroblasts, for mutations at the lacZ locus. When comparing mutant with wild-type mice, we observed a significantly higher number of genome rearrangements in liver and spleen and a significantly lower number of point mutations in liver and brain. The reduced point mutation frequency was not due to a decrease in small deletion mutations thought to be a hallmark of NHEJ, but could be a consequence of increased cellular responses to unrepaired DSBs. Indeed, we found a substantial increase in persistent 53BP1 and γH2AX DNA damage foci in Ku80−/− as compared to wild-type liver. Treatment of cultured Ku80-deficient or wild-type embryonic fibroblasts, either proliferating or quiescent, with hydrogen peroxide or bleomycin showed no differences in the number or type of induced genome rearrangements. However, after such treatment, Ku80-deficient cells did show an increased number of persistent DNA damage foci. These results indicate that Ku80-dependent repair of DNA damage is predominantly error-free with the effect of alternative more error-prone pathways creating genome rearrangements only detectable after extended periods of time, i.e., in young adult animals. The observed premature aging likely results from a combination of increased cellular senescence and an increased load of stable, genome rearrangements
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