The derivations of some evolution algebras

In this work we investigate the derivations of n−dimensional complex evolution algebras, depending on the rank of the appropriate matrices. For evolution algebra with non-singular matrices we prove that the space of derivations is zero. The spaces of derivations for evolution algebras with matrices of rank n−1 are described.Junta de Andalucía FQM-14

On the instability for an incremental problem in elastodynamics

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGIn this short note, we consider some issues regarding the instability of some elastodynamical problems when the elasticity tensor is not positive definite. By using the so-called logarithmic convexity argument, we prove the instability of solutions when the time derivative of the elasticity tensor is semi-definite negative or it satisfies another restriction on the coefficients. The uniqueness of the solution is also concluded. Finally, a simple one-dimensional example is provided to demonstrate the numerical behaviour of the instability.Ministerio de Ciencia, Innovación y Universidades | Ref. PID2019-105118GB-I0

Endotoxin-induced disseminated intravascular coagulation in rabbits: effect of recombinant hirudin on hemostatic parameters, fibrin deposits, and mortality

We evaluated the effect of r-hirudin on an experimental model of disseminated intravascular coagulation (DIC) in rabbits, through the continuous infusion of 100 microg/kg/hr of Escherichia coli endotoxin for a period of 6 hours. r-Hirudin (0.05, 0.3, and 0.6 mg/kg/hr) as treatment, or saline solution as placebo, were administered simultaneously with endotoxin. Severe DIC in the endotoxin control group was shown by impairment in hemostatic parameters, kidney fibrin deposition, and a high mortality rate. Medium and high doses of r-hirudin led to an improvement in such DIC-related parameters as platelet numbers and fibrinogen and protein C concentrations. High-dose r-hirudin also reduced consumption of antithrombin III (ATIII). All doses of r-hirudin prevented decreases in tissue plasminogen activator (t-PA) and reduced the increase in plasminogen activator inhibitor-1 (PAI-1) activity observed at 2 hours after endotoxin administration. A significant reduction in kidney fibrin deposition was seen in medium- and high-dose r-hirudin groups. Additionally, the mortality rate in rabbits receiving medium- and high-dose r-hirudin was 10%, and that in rabbits receiving low-dose r-hirudin was 20%, as compared with a mortality rate of 70% in the control group. Protein C activity was significantly lower (p < 0.001) in nonsurviving rabbits. Moreover, there was a strong positive correlation (r = 0.68, p < 0.001) between protein C consumption and kidney fibrin deposition. We conclude that r-hirudin can be a useful drug in the clinical treatment of DIC

Numerical analysis of a thermoelastic dielectric problem arising in the Moore–Gibson–Thompson theory

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGIn this paper, we numerically study a thermoelastic problem arising in the Moore– Gibson–Thompson theory. Dielectrics effects are also included within the model. The corresponding problem is written in terms of the displacement field, the temperature and the electric potential. A viscous term is added in the heat equation to provide the numerical analysis of the corresponding variational problem. Then, by using the finite element method and the implicit Euler scheme fully discrete approximations are introduced. A discrete stability property and a priori error estimates are obtained. Finally, one- and two-dimensional numerical simulations are shown to demonstrate the accuracy of the approximation and the behavior of the solutionMinisterio de Ciencia; Innovación y Universidades | Ref. PGC2018-096696-B-I00Ministerio de Ciencia; Innovación y Universidades | Ref. PID2019-105118GB-I0

Hemostatic markers in surgery: a different fibrinolytic activity may be of pathophysiological significance in orthopedic versus abdominal surgery

Without prophylaxis, patients subjected to major abdominal surgery have a risk of deep vein thrombosis of approximately 30%, while the rate varies between 40% and 60% in orthopedic surgery. The reasons for this discrepancy are not completely understood. The present study was designed to compare the pre- and postoperative behavior of different coagulation and fibrinolysis parameters in patients undergoing both types of surgery, receiving low molecular weight heparin prophylaxis. Samples were taken before operation and on postoperative days 1, 3, and 7. The following parameters were assessed: prothrombin fragment 1 + 2, thrombin-antithrombin III complexes, fibrinopeptide A, tissue plasminogen activator, plasminogen activator inhibitor, plasmin-alpha 2-antiplasmin complexes, and fibrin degradation products. We found a significant increase in the clotting markers postoperatively compared with preoperative values (P < 0.05), both in abdominal and orthopedic surgery, indicating a marked hemostatic activation which remained until postoperative day 7. A significant increase in plasminogen activator inhibitor (P < 0.01) and a decrease in tissue plasminogen activator and plasmin-alpha 2-antiplasmin complexes was also observed early after operation. The plasminogen activator inhibitor activity decreased, while tissue plasminogen activator and plasmin-alpha 2-antiplasmin levels increased significantly on days 3 and 7 (P < 0.05). Fibrin degradation products significantly increased throughout the postoperative period (P < 0.01). Preoperatively, we found higher plasminogen activator inhibitor activity and lower tissue plasminogen activator and plasmin-alpha 2-antiplasmin complexes (P < 0.05) in patients undergoing hip replacement compared with abdominal surgery. Fibrin degradation products were also significantly lower on postoperative day 3 in patients undergoing hip replacement (P < 0.01). We suggest that the lower preoperative fibrinolytic activation observed in patients undergoing orthopedic surgery compared with abdominal surgery might have pathophysiological consequences. Our results also indicate that the hemostatic activation persists beyond the 7th postoperative day despite prophylaxis

Anticoagulant treatment and survival in cancer patients. The evidence from clinical studies

The association between cancer and an increased incidence of venous thromboembolism (Trousseau syndrome) is well characterized and recent studies have shown that the hemostatic system plays a key role at different stages in the process of tumorigenesis. Anticoagulant drugs therefore appear to be an attractive strategy in cancer therapy, with an effect that would surpass the benefit of preventing thrombosis. This hypothesis was initially supported by the post-hoc analysis of clinical trials not primarily designed to evaluate the effect of anticoagulants, mainly low molecular weight heparins (LMWH), on cancer survival. Other studies regarding the addition of unfractionated heparin or oral anticoagulants to standard cancer treatment offered controversial results. However, recent investigations among cancer patients without deep venous thrombosis, with cancer-related mortality as the primary end point, suggest that at least in some patients LMWH may exert an antineoplastic effect in vivo and alter the natural history of malignant disease by increasing the response rates and, therefore, improving survival. Additional research on this field is needed to clarify the biological mechanisms involved and to answer yet unsolved questions such as the types of tumor and stages of disease most suitable for this treatment as well as how to optimize treatment regimens

Long term evaluation of high tibial valgus osteotomy

We present a long term evaluation of 100 high valgus tibial osteotomies with a mean follow up of 11 years. Knees with slight or moderate osteoarthritis had the best results. Slight overcorrection was beneficial, but gross overcorrection was not. There were few complications and the overall long term results were go

A constitutive model for analyzing martensite formation in austenitic steels deforming at high strain rates

This study presents a constitutive model for steels exhibiting SIMT, based on previous sem inal works, and the corresponding methodology to estimate their parameters. The model includes temperature effects in the phase transformation kinetics, and in the softening of each solid phase through the use of a homogenization technique. The model was validated with experimental results of dynamic tensile tests on AISI 304 sheet steel specimens, and their predictions correlate well with the experimental evidence in terms of macroscopic stress strain curves and martensite volume fraction formed at high strain rates. The work shows the value of considering temperature effects in the modeling of metastable austen itic steels submitted to impact conditions. Regarding most of the works reported in the lit erature on SIMT, modeling of the martensitic transformation at high strain rates is the distinctive feature of the present paper.The researchers of the University Carlos III of Madrid are indebted to the Comunidad Autónoma de Madrid (Project CCG10 UC3M/DPI 5596)) and to the Ministerio de Ciencia e Innovación de España (Project DPI/2008 06408) for the financial support received which allowed conducting part of this work. The authors express their thanks to Mr. Philippe and Mr. Tobisch from the company Zwick for the facilities provided to perform the tensile tests at high strain rates.Publicad

Tumour-marker levels and prognosis in malignant teratoma of the testis

The effect of 6 putative prognostic factors on survival was studied in patients with Stages III and IV malignant teratoma of the testis. Differences between survival curves were tested for statistical significance. A diameter greater than 5 cm in the largest tumour mass, and greater than 8 pulmonary metastases were adverse prognostic factors (P = 0.004 and 0.008 respectively). Patients with malignant teratoma, trophoblastic, fared worse than those with malignant teratoma, undifferentiated, and malignant teratoma, intermediate (P = 0.011 and 0.023 respectively). Previous chemotherapy or radiotherapy had no significant effect. Serum alpha-foetoprotein (AFP) above 10(3) MRC u/ml and serum beta subunit of human chorionic gonadotrophin (hCG) above 10(5) miu/ml, were found to predict a poor prognosis (P = 0.010 and 0.001 respectively). A combination of measurements of the tumour markers gave the most consistent indication of prognosis, in that patients with either AFP greater than 10(3) MRC u/ml or hCG greater than 10(5) miu/ml, or both, fared much worse than those with neither factor (P = 0.001). Serum concentrations of AFP and hCG should be stated in reports of treatment of testicular teratoma in order to provide a basis for comparison with other series. Regular and frequent measurements of these markers are appropriate throughout the clinical management of patients with malignant teratoma