Numerical modelling of hip fracture patterns in human femur

[EN] Background and Objective: Hip fracture morphology is an important factor determining the ulterior surgical repair and treatment, because of the dependence of the treatment on fracture morphology. Although numerical modelling can be a valuable tool for fracture prediction, the simulation of femur fracture is not simple due to the complexity of bone architecture and the numerical techniques required for simulation of crack propagation. Numerical models assuming homogeneous fracture mechanical properties commonly fail in the prediction of fracture patterns. This paper focuses on the prediction of femur fracture based on the development of a finite element model able to simulate the generation of long crack paths. Methods: The finite element model developed in this work demonstrates the capability of predicting fracture patterns under stance loading configuration, allowing the distinction between the main fracture paths: intracapsular and extracapsular fractures. It is worth noting the prediction of different fracture patterns for the same loading conditions, as observed during experimental tests. Results and conclusions: The internal distribution of bone mineral density and femur geometry strongly influences the femur fracture morphology and fracture load. Experimental fracture paths have been analysed by means of micro-computed tomography allowing the comparison of predicted and experimental crack surfaces, confirming the good accuracy of the numerical model.The authors are indebted to University Complutense of Madrid and to the radiological team of the Hospital Universitario Infanta Leonor for supporting the experimental work on human bones included in this paper. The micro-CTs were performed in the Micro-Computed Tomography laboratory at CENIEH facilities with the collaboration of CENIEH staff. The authors gratefully acknowledge the funding support received from the Spanish Ministry of Economy and Competitiveness and the FEDER operation program for funding the projects DPI2013-46641-R, DPI2017-89197-C2-1-R, DPI2017-89197-C2-2-R, RTC-2015-3887-8 and the Generalitat Valenciana through theproject Prometeo/2016/007. The authors also acknowledge the funding support received from the Fundacion Espanola de Investigacion Osea y del Metabolismo Mineral through the 2018 research fellowship program.Marco, M.; Giner Maravilla, E.; Caeiro-Rey, JR.; Miguélez, MH.; Larrainzar-Garijo, R. (2019). Numerical modelling of hip fracture patterns in human femur. Computer Methods and Programs in Biomedicine. 173:67-75. https://doi.org/10.1016/j.cmpb.2019.03.010S677517

A perturbative solution for gravitational waves in quadratic gravity

We find a gravitational wave solution to the linearized version of quadratic gravity by adding successive perturbations to the Einstein's linearized field equations. We show that only the Ricci squared quadratic invariant contributes to give a different solution of those found in Einstein's general relativity. The perturbative solution is written as a power series in the $\beta$ parameter, the coefficient of the Ricci squared term in the quadratic gravitational action. We also show that, for monochromatic waves of a given angular frequency $\omega$, the perturbative solution can be summed out to give an exact solution to linearized version of quadratic gravity, for $0<\omega<c/\mid\beta\mid^{1/2}$. This result may lead to implications to the predictions for gravitational wave backgrounds of cosmological origin.Comment: 9 pages, to appear in CQ

Validation of Calprotectin As a Novel Biomarker For The Diagnosis of Pleural Effusion: a Multicentre Trial

Discriminating between malignant pleural effusion (MPE) and benign pleural effusion (BPE) remains difficult. Thus, novel and efficient biomarkers are required for the diagnosis of pleural effusion (PE). The aim of this study was to validate calprotectin as a diagnostic biomarker of PE in clinical settings. A total of 425 patients were recruited, and the pleural fluid samples collected had BPE in 223 cases (53.7%) or MPE in 137 patients (33%). The samples were all analysed following the same previously validated clinical laboratory protocols and methodology. Calprotectin levels ranged from 772.48 to 3,163.8 ng/mL (median: 1,939 ng/mL) in MPE, and 3,216-24,000 ng/mL in BPE (median: 9,209 ng/mL; p < 0.01), with an area under the curve of 0.848 [95% CI: 0.810-0.886]. For a cut-off value of </= 6,233.2 ng/mL, we found 96% sensitivity and 60% specificity, with a negative and positive predictive value, and negative and positive likelihood ratios of 96%, 57%, 0.06, and 2.4, respectively. Multivariate analysis showed that low calprotectin levels was a better discriminator of PE than any other variable [OR 28.76 (p < 0.0001)]. Our results confirm that calprotectin is a new and useful diagnostic biomarker in patients with PE of uncertain aetiology which has potential applications in clinical practice because it may be a good complement to cytological methods

Universal restrictions to the conversion of heat into work derived from the analysis of the Nernst theorem as a uniform limit

We revisit the relationship between the Nernst theorem and the Kelvin-Planck statement of the second law. We propose that the exchange of entropy uniformly vanishes as the temperature goes to zero. The analysis of this assumption shows that is equivalent to the fact that the compensation of a Carnot engine scales with the absorbed heat so that the Nernst theorem should be embedded in the statement of the second law. ----- Se analiza la relaci{\'o}n entre el teorema de Nernst y el enunciado de Kelvin-Planck del segundo principio de la termodin{\'a}mica. Se{\~n}alamos el hecho de que el cambio de entrop{\'\i}a tiende uniformemente a cero cuando la temperatura tiende a cero. El an{\'a}lisis de esta hip{\'o}tesis muestra que es equivalente al hecho de que la compensaci{\'o}n de una m{\'a}quina de Carnot escala con el calor absorbido del foco caliente, de forma que el teorema de Nernst puede derivarse del enunciado del segundo principio.Comment: 8pp, 4 ff. Original in english. Also available translation into spanish. Twocolumn format. RevTe

Centro de atenci?n residencial geri?trico ?Hilos de plata?, orientado en la atenci?n integral del adulto mayor con trastornos mentales, Lima-Per?

La presente tesis propone la idea de negocio de un centro de atenci?n residencial geri?trico ?Hilos de Plata?, dedicada a brindar un servicio gerontol?gico y geri?trico integral y exclusivo con enfoque personalizado en la atenci?n y cuidado del adulto mayor con enfermedades mentales, pudiendo tener comorbilidades comunes no complicadas y pertenecientes al NSE A, B y C en la ciudad de Lima. Esto se evalu? a partir de estudios de mercado cuantitativos y cualitativos que mostraron aceptaci?n por parte de familiares de adultos mayores. El plan de mercadotecnia propone llegar a ser uno de los mejores centros de atenci?n residencial geri?trico de Lima, atendiendo a adultos mayores con trastornos mentales. Operativamente la residencia funcionar? en Cieneguilla y se cuenta con dos principales procesos: la inspecci?n inicial al momento de recibir al adulto mayor y el monitoreo constante. Cabe se?alar que los colaboradores deber?n cumplir con los perfiles que ser?n rigurosamente evaluados por los accionistas. Los planes funcionales desarrollados requieren de presupuestos que son incluidos en la inversi?n y proyecciones del negocio. Se requiere una inversi?n inicial de S/ 414,186 que ser?n financiados por los accionistas, con un costo de oportunidad de 13.7% obteni?ndose un VAN de S/ 420,867

Sustained blood glutamate scavenging enhances protection in ischemic stroke

Stroke is a major cause of morbidity, mortality, and disability. During ischemic stroke, a marked and prolonged rise of glutamate concentration in the brain causes neuronal cell death. This study explores the protective effect of a bioconjugate form of glutamate oxaloacetate transaminase (hrGOT), which catalyzes the depletion of blood glutamate in the bloodstream for ~6 days following a single administration. When treated with this bioconjugate, a significant reduction of the infarct volume and a better retention of sensorimotor function was observed for ischemic rats compared to those treated with saline. Moreover, the equivalent dose of native hrGOT yielded similar results to the saline treated group for some tests. Targeting the bioconjugate to the blood-brain-barrier did not improve its performance. The data suggest that the bioconjugates draw glutamate out of the brain by displacing homeostasis between the different glutamate pools of the body

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research