A computational framework for polyconvex large strain elasticity for geometrically exact beam theory

In this paper, a new computational framework is presented for the analysis of nonlinear beam finite elements subjected to large strains. Specifically, the methodology recently introduced in Bonet et al. (Comput Methods Appl Mech Eng 283:1061–1094, 2015) in the context of three dimensional polyconvex elasticity is extended to the geometrically exact beam model of Simo (Comput Methods Appl Mech Eng 49:55–70, 1985), the starting point of so many other finite element beam type formulations. This new variational framework can be viewed as a continuum degenerate formulation which, moreover, is enhanced by three key novelties. First, in order to facilitate the implementation of the sophisticated polyconvex constitutive laws particularly associated with beams undergoing large strains, a novel tensor cross product algebra by Bonet et al. (Comput Methods Appl Mech Eng 283:1061–1094, 2015) is adopted, leading to an elegant and physically meaningful representation of an otherwise complex computational framework. Second, the paper shows how the novel algebra facilitates the re-expression of any invariant of the deformation gradient, its cofactor and its determinant in terms of the classical beam strain measures. The latter being very useful whenever a classical beam implementation is preferred. This is particularised for the case of a Mooney–Rivlin model although the technique can be straightforwardly generalised to other more complex isotropic and anisotropic polyconvex models. Third, the connection between the two most accepted restrictions for the definition of constitutive models in three dimensional elasticity and beams is shown, bridging the gap between the continuum and its degenerate beam description. This is carried out via a novel insightful representation of the tangent operator

HDG-NEFEM with Degree Adaptivity for Stokes Flows

This paper presents the first degree adaptive procedure able to directly use the geometry given by a CAD model. The technique uses a hybridisable discontinuous Galerkin discretisation combined with a NURBS-enhanced rationale, completely removing the uncertainty induced by a polynomial approximation of curved boundaries that is common within an isoparametric approach. The technique is compared against two strategies to perform degree adaptivity currently in use. This paper demonstrates, for the first time, that the most extended technique for degree adaptivity can easily lead to a non-reliable error estimator if no communication with CAD software is introduced whereas if the communication with the CAD is done, it results in a substantial computing time. The proposed technique encapsulates the CAD model in the simulation and is able to produce reliable error estimators irrespectively of the initial mesh used to start the adaptive process. Several numerical examples confirm the findings and demonstrate the superiority of the proposed technique. The paper also proposes a novel idea to test the implementation of high-order solvers where different degrees of approximation are used in different elements

A unified approach for a posteriori high-order curved mesh generation using solid mechanics

The paper presents a unified approach for the a posteriori generation of arbitrary high-order curvilinear meshes via a solid mechanics analogy. The approach encompasses a variety of methodologies, ranging from the popular incremental linear elastic approach to very sophisticated non-linear elasticity. In addition, an intermediate consistent incrementally linearised approach is also presented and applied for the first time in this context. Utilising a consistent derivation from energy principles, a theoretical comparison of the various approaches is presented which enables a detailed discussion regarding the material characterisation (calibration) employed for the different solid mechanics formulations. Five independent quality measures are proposed and their relations with existing quality indicators, used in the context of a posteriori mesh generation, are discussed. Finally, a comprehensive range of numerical examples, both in two and three dimensions, including challenging geometries of interest to the solids, fluids and electromagnetics communities, are shown in order to illustrate and thoroughly compare the performance of the different methodologies. This comparison considers the influence of material parameters and number of load increments on the quality of the generated high-order mesh, overall computational cost and, crucially, the approximation properties of the resulting mesh when considering an isoparametric finite element formulation

Surgical management of severe pancreatic fistula after pancreatoduodenectomy: a comparison of early versus late rescue pancreatectomy

Background: Rescue pancreatectomy for postoperative pancreatic fistula (POPF) after pancreatoduodenectomy (PD) is associated with high mortality. However, in-depth literature is scarce and hard to interpret. This study aimed to evaluate the indications, timing and perioperative outcomes of rescue pancreatectomy for severe POPF after PD. Methods: Retrospective single-centre study from all consecutive patients (2008–2020) with POPF-C after PD (ISGPS 2016 definition). Major morbidity and mortality during hospitalization or within 90 days after index surgery were evaluated. Time from index surgery to rescue pancreatectomy was dichotomized in early and late (≤ 11 versus > 11 days). Results: From 1076 PDs performed, POPF-B/C occurred in 190 patients (17.7%) of whom 53 patients (4.9%) with POPF-C were included. Mortality after early rescue pancreatectomy did not differ significantly compared to late rescue pancreatectomy (13.6% versus 35.3%; p = 0.142). Timing of a rescue pancreatectomy did not change significantly during the study period: 11 (IQR, 8–14) (2008–2012) versus 14 (IQR, 7–33) (2013–2016) versus 8 days (IQR, 6–11) (2017–2020) (p = 0.140). Over time, the mortality in patients with POPF grade C decreased from 43.5% in 2008–2012 to 31.6% in 2013–2016 up to 0% in 2017–2020 (p = 0.014). However, mortality rates after rescue pancreatectomy did not differ significantly: 31.3% (2008–2012) versus 28.6% (2013–2016) versus 0% (2017–2020) (p = 0.104). Conclusions: Rescue pancreatectomy for severe POPF is associated with high mortality, but an earlier timing might favourably influence the mortality. Hypothetically, this could be of value for pre-existent vulnerable patients. These findings must be carefully interpreted considering the sample sizes and differences among subgroups by patient selection

Comparison of anxiety, depression and stress and emotional self-regulation in normal and divorced women

Because of stressful conditions, divorced women are vulnerable of psychiatric problems. The main purpose of this study is to compare anxiety, depression, stress and emotion self-regulation in divorced and normal women. The present study is a kind of analytical-comparative research and statistical population consists of all divorced women of Tehran referred to several counseling centers by 2015. From these women, 42 women were volunteered to participate in the study. Inclusion criterion was having divorce history for at least 2 years. The individuals were compared to 38 married women with no history of divorce in terms of anxiety, depression and stress and emotion self-regulation. All samples fulfilled depression, anxiety, stress and emotion regulation questionnaires. To compare depression, anxiety and emotion self-regulation between two groups of normal and divorced women, parametric independent t-test and Mann-Whitney nonparametric test has been applied. The data analyzed by SPSS22. Obtained results showed that there is significant difference between normal and divorced women in terms of emotion self-regulation (p = 0.005). However, no significant difference was observed in scores of depression, anxiety and stress in two groups. Emotion dysregulation is a severe problem in divorced women. © Medwell Journals, 2016

Impact of Endocrine and Exocrine Insufficiency on Quality of Life After Total Pancreatectomy

Background: Total pancreatectomy (TP) is rarely performed due to concerns for endocrine and exocrine insufficiency and decreased quality of life (QoL). Renewed interest is seen in recent years, but large cohort studies remain scarce. This study was designed to evaluate endocrine and exocrine insufficiency after TP and its impact on QoL. Methods: Adult patients (age ≥ 18 years) who underwent TP between 2008 and 2017 at Karolinska University Hospital with at least 6 months follow-up were included. Endocrine and exocrine insufficiency and QoL were assessed using validated questionnaires (EORTC QLQ-C30, QLQ-PAN26, PAID20, and DTSQs). Both pre- and postoperative questionnaires were available in a subgroup. Results: Of 145 TP, 60 patients were eligible of whom 53 (88.3%) with a median of 21 months (interquartile range [IQR] 13–54) follow-up were included. Symptomatic hypoglycemia occurred in 90.6% (48/53) of patients, and 25% (12/48) experienced ≥ 1 episodes of loss of consciousness. The PAID20 revealed emotional burnout in seven patients (13.2%), whereas a high satisfaction score of diabetes treatment (median 28, IQR 24–32) was measured according to the DTSQs. Overall, 27 patients (50.9%) reported to have steatorrhea during a median of 2 days (IQR 0–4) in the past week. Overall QoL was reduced compared with a general population (66.7% vs. 76.4%; Δ9.7%) but did not differ with preoperative outcomes (n = 39, 66.7%; IQR 41.7–83.3 vs. 66.7%, IQR 50.0–83.3; P = 0.553) according to the EORTC QLQ-C30. Conclusions: Although the impact of endocrine and exocrine insufficiency on QoL after TP seems acceptable, the management of both insufficiencies should be further improved

The frequency of p53, Ki67, CD99 and Fli-1 protein expression in paraffin-embedded tissue blocks in Ewing’s sarcoma

"n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Ewing sarcoma family tumors (ESFTs) are among the most malignant tumors in children and young adults. ESFTs include Ewing sarcoma (ES) and peripheral primitive neuroectodermal tumors (pPNETs). As there seemed to be few studies on the molecular biology of ESFTs, we investigated the frequency of CD99, Ki67, p53 and Fli-1 protein expression in 15 Iranian patients with ESFTs. In addition, the correlation between expression rate of these proteins and various clinical factors, including age, sex and survival was computed."n"nMethods: The expression of the aforesaid proteins was studied by immunohisto-chemistry in formalin-fixed and paraffin-embedded blocks of 15 ESFTs specimens. Stained sections were classified according to the percentage of stained tumor cells."n"nResults: The results showed the membrane expression of CD99 protein in all of the specimens. The nuclear expression of Fli-1 protein was observed in 86.7% and the over-expression of p53 nuclear protein was seen in 53.3% of the specimens. The expression rate of Ki67 protein was 60%. Although a significant correlation was not shown between the expression levels of Ki67, p53 or Fli-1 proteins with age, sex or survival of the patients, there was a significant correlation between expression levels of p53 and Ki67 proteins (P=0.003)."n"nConclusion: The results underline the role of p53 and Ki67 proteins in the development and progression of ESFTs and suggest the simultaneous immunohistochemical staining of Fli-1 and CD99 proteins for the diagnosis of ESFTs

Photocoagulation results in changes in gene expression.

<p><i>IL1β, IL8, HMGA2, TGFBR2, ADAMTS6, TIMP3, HSPA6, IL33</i> and <i>ANKRD1</i> mRNA expression in ARPE-19 cells 24 h after photocoagulation and in control non-irradiated cells. Measurements were performed by qPCR using cyclophilin B as an endogenous control. ***<i>p</i><0.001; **<i>p</i><0.01 and *<i>p</i><0.05 vs. control; <i>n</i>≥6.</p

Transient increase in apoptosis in ARPE-19 cells after photocoagulation.

<p><b>A)</b> Representative images showing apoptotic ARPE-19 cells visualized by TUNEL-staining (brown) at various time-points after <i>in vitro</i> photocoagulation. Scale bar represents 100 µm; magnification 10X. <b>B)</b> Summarized data showing measurements of cytoplasmic histone-associated DNA fragments in cell homogenates and culture media at various time-points after <i>in vitro</i> photocoagulation. Data is expressed as mean absorbance ratio between the photocoagulated samples and the corresponding non-irradiated controls for each time-point (apoptosis enrichment factor). Six to 8 samples were analyzed for each time-point. ***<i>p</i><0.001 vs 12 h and vs 48 h in the cell-homogenates; **<i>p</i><0.01 vs 48 h and vs 168 h in the medium.</p