This paper presents the numerical resolution of unilateral boundary conditions able to effectively model several problems of unsaturated flow, as those involving rainfall infiltration and seepage ...faces. Besides the penalty technique, we also consider the novel regularization of these conditions by means of the more effective augmented Lagrangian method. The performance of the so‐obtained finite element method is carefully investigated in terms of accuracy and ill‐conditioning effects, including comparisons with analytical solutions and a complete identification of the analogies with the problem of frictionless contact. In this way, we provide a priori estimates of optimal and admissible ranges for the penalty coefficient as functions of permeability and spatial discretization. The proposed method and the estimated coefficient ranges are validated in further numerical examples, involving the propagation of a wetting front due to rainfall and the partial saturation of an aged concrete dam. These applications show that the proposed regularizations do not induce any detrimental effect on solution accuracy and on convergence rate of the employed Newton‐Raphson method. Hence, the present approach should be preferred to the commonly used iterative switching between the imposed‐flow and the imposed‐pressure conditions, which often leads to spurious oscillations and convergence failures.
Key Points
Novel regularization of proposed conditions by augmented Lagrangian method
Novel analysis of accuracy and ill‐conditioning of regularizations
Novel evaluation of penalty coefficient as functions of permeability and mesh
This paper considers the analysis and numerical simulation of strong discontinuities in partially saturated solids. The goal is to study observed localized failures in such media like shear bands and ...similar. The developments consider a fully coupled partially saturated elastoplastic model for the (continuum) bulk response of the solid formulated in effective stresses, identifying the necessary mathematical conditions for the appearance of strong discontinuities (that is, discontinuities in the displacement field leading to singular strains) as well as the proper treatment for the fields characterizing the flow of the different fluid phases, namely, the fluid contents of these phases and their individual pore pressures. The geometrically linear range of infinitesimal strains is considered. These developments allow the formulation of multiphase cohesive laws along the strong discontinuity, capturing in this way the coupled localized dissipation observed in the aforementioned failures. Furthermore, the paper also presents the formulation of enhanced finite elements capturing all these discontinuous solutions in general unstructured meshes. In particular, the finite elements capture the strong discontinuity through the proper enhancements of the discrete element strains, allowing for a complete local resolution of these effects. This results in a particularly efficient computational approach, easily accommodated in an existing finite element code. Different representative numerical simulations are presented illustrating the performance of the proposed formulation, as well as its use in practical applications like the modeling of the excavation of tunnels in variably saturated media.
This work presents a finite element formulation of equations proposed in a companion paper to describe the hyperelastic response of three-phase porous media. Attention is paid to the development of ...consistent tangents required by the Newton–Raphson procedure used to solve the highly non-linear finite element equations. Among several sources of non-linearity, we also model the permeability dependence on strain as typically observed in intensely jointed rock masses, thus introducing a further reason of hydro-mechanical coupling. Several numerical examples are presented to validate the considered poro-elastic laws and to assess the performance of the numerical formulation. These tests include comparisons with available experimental data relative to a sand column desaturation and with the Philip’s analytical solution for the propagation of a saturation front in an initially dry porous solid. Finally, the formulation is applied to problems of interest for dam engineering, namely the simulation of reservoir bank response to rapid drawdown and a three-dimensional study of concrete gravity dam interaction with foundation and abutment rock masses during reservoir operation.
We aimed to review the role of different types of imaging (computed tomography СТ, ultrasonography US, magnetic resonance imaging MRI) in measuring the optic nerve diameter (OND) and optic nerve ...sheath diameter (ONSD) in adults and the potential advantages and limitations of each modality. A literature search was carried out using ResearchGate, Saudi Digital Library, Google Scholar, and Mendeley databases between 2010 and 2021 (papers presented in English) with the keywords “computed tomography,” “magnetic resonance imaging,” “ultrasonography,” “optic nerve sheath diameter,” and “optic nerve diameter.” Of the 60 articles analyzed, 42 were included in the review. Compared to ONSD, the evidence for OND appeared to be more limited. After comparing all three imaging modalities (CT, MRI, and US), we concluded that for the most accurate measurements of ONSD we should be using MRI (range: 4.0–6.0 mm). CT (range: 4.4–6.7 mm) would provide the second most exact measurements after MRI. Although CT and MRI provide the most consistent and accurate measurements, ultrasound is more commonly used (ONSD range: 3.4–7.7 mm) due to it’s being non-invasive, easy to use, and easily available anywhere, from big hospitals to small clinics, unlike CT and MRI. All three imaging modalities can provide good measurements, and hopefully, soon ultrasound will be as accurate as MRI in measuring the optic nerve.
Scorpionism is a public health problem in many tropical countries, especially in North Africa, South India, Latin America and the Middle East. In Brazil, patients with severe scorpion envenoming have ...mainly cardiovascular events, including acute heart failure, acute respiratory distress syndrome and shock, death is rare. We described 58 accidents presumably caused by Tityus obscurus in Brazilian Amazonia. Patients reported a sensation of “electric shocks” which could last hours. The vast majority of patients presented a clinical picture compatible with acute cerebellar dysfunction, beginning minutes and lasting up to 2 days after the accident. They presented cerebellar ataxia, dysdiadochokinesia, dysmetry, dysarthria, dyslalia, nausea and vomiting. Besides, some patients presented myoclonus and fasciculation which can also be attributed to cerebellar dysfunction or maybe the result of direct action on skeletal muscle. Two patients had evidence of intense rhabdomyolysis and acute kidney injury. The clinical picture in this scorpion envenoming is mainly characterized by an acute dysfunction of cerebellar activities and abnormal neuromuscular manifestations and in some cases muscle injury which are not described in any other region of the world. This work presents clinical, epidemiologic, laboratory and treatment aspects of this unmatched scorpion envenoming in the state of Pará, northern Brazil.
•We describe 58 envenoming caused presumably by Tityus obscurus in Brazilian Amazonia.•Clinical effects of envenoming are compatible with acute cerebellar dysfunction.•Myoclonus and fasciculation can be attributed to cerebellar or muscle dysfunction.•Six patients developed rhabdomyolysis and two acute kidney injury.•Envenoming by these scorpions appears to be unique to Brazil.
Injuries caused by freshwater stingray are common in several regions of South America, although they are underreported. The riverside inhabitants are the main victims in the Amazonian and Midwest ...regions of South America. The fishermen are injured mainly in the new focus of colonization of the rivers by freshwater stingrays. With the increasing population in these regions, where freshwater stingrays are found, there has been a significant increase in injuries within the general population. The highest increase occurred among tourists from other regions, where these animals are not known, when visiting these areas.
The envenomations from the stingray causes prolonged and intense pain, both local and regionally. Generally these are associated with other local inflammatory manifestations, such as swelling and erythema. The injury often progresses to necrosis and it is considered potentially tetanogenic. A secondary infection is also a frequent local complication and most frequently is caused by Aeromonas species, usually Aeromonas hydrophila. Herein we report the first 2 cases of tetanus after freshwater stingray injuries: a 51-year-old men who had tetanus and recovered without sequel and the second a 67-year-old men who had severe tetanus and a deep, necrotizing soft-tissue infection with sepsis, septic shock and evolution to death.
•We describe two cases of tetanus after freshwater stingray injury in Brazilian Amazonia.•Both patients presented local infection and one died due to septic shock.•This envenomation evolves with severe and prolonged pain, swelling and erythema.•This injury can cause infection, necrosis and is a potentially tetanogenic wound.•Aeromonas sp is often associated with secondary infection after trauma in fresh water.
The melanoma patient's immune response to tumor has been extensively studied. Yet, the frequently observed coexistence of tumor-associated Ag (TAA)-specific T cells with their target cells in vivo ...remains unexplained. Loss of TAA expression might contribute to this paradox. We studied TAA expression in metastases by obtaining fine-needle aspirations from 52 tumor lesions in 30 patients with melanoma before and soon after immunotherapy. Limitations due to low amounts of starting material were overcome with a high fidelity antisense RNA amplification method. TAA expression was measured by quantitative real-time PCR of anti-sense RNA. Decrease in gp100/Pmel-17 TAA preceded tumor disappearance in several instances and could be best explained by immune selection because most patients had received gp100/Pmel-17-specific vaccination. Conversely, immune selection was absent in nonregressing lesions. These observations suggest that vaccination, when successful, triggers a broad inflammatory reaction that can lead to tumor destruction despite immune selection. Additionally, lack of clinical response might be attributed to lack of this initiating event rather than immune escape. This study provides an insight into the natural history of tumors and defines a strategy for the characterization of gene expression in tumors during therapy.
We investigated the combination of lymphodepleting chemotherapy followed by the adoptive transfer of autologous tumor reactive lymphocytes for the treatment of patients with refractory metastatic ...melanoma.
Thirty-five patients with metastatic melanoma, all but one with disease refractory to treatment with high-dose interleukin (IL) -2 and many with progressive disease after chemotherapy, underwent lymphodepleting conditioning with two days of cyclophosphamide (60 mg/kg) followed by five days of fludarabine (25 mg/m(2)). On the day following the final dose of fludarabine, all patients received cell infusion with autologous tumor-reactive, rapidly expanded tumor infiltrating lymphocyte cultures and high-dose IL-2 therapy.
Eighteen (51%) of 35 treated patients experienced objective clinical responses including three ongoing complete responses and 15 partial responses with a mean duration of 11.5 +/- 2.2 months. Sites of regression included metastases to lung, liver, lymph nodes, brain, and cutaneous and subcutaneous tissues. Toxicities of treatment included the expected hematologic toxicities of chemotherapy including neutropenia, thrombocytopenia, and lymphopenia, the transient toxicities of high-dose IL-2 therapy, two patients who developed Pneumocystis pneumonia and one patient who developed an Epstein-Barr virus-related lymphoproliferation.
Lymphodepleting chemotherapy followed by the transfer of highly avid antitumor lymphocytes can mediate significant tumor regression in heavily pretreated patients with IL-2 refractory metastatic melanoma.
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