Poder de mercado y estrategias: el método de máxima entropía generalizada

El presente trabajo hace una revisión de los principales conceptos vinculados a la estimación por máxima entropía y su aplicación al ámbito de la organización industrial. Se exponen las particularidades del método, y cómo puede utilizarse para la estimación directa de las estrategias en un juego a partir de un modelo multinomial de elección discreta. A tal fin, se propone una estructura de mercado donde la variable de decisión de las firmas es el precio bajo un esquema no cooperativo. Finalmente, se hace una aplicación del método al caso del mercado argentino de Kerosene

“Análisis del comportamiento mecánico de mezclas asfálticas en caliente incorporando polímeros SBS en la Av. Universitaria cuadra 53 al 57- Comas, Lima 2017”

El presente proyecto de investigación tiene como objetivo principal determinar que de manera la incorporación de polímeros SBS mejora el comportamiento mecánico con respecto al asfalto convencional en la Av. Universitaria. Se especifican el uso del asfalto PEN 60/70 y agregados provenientes de la cantera “Leticia Cerro Blanco”, las cuales han sido ensayados de acuerdo a procedimientos y especificaciones indicados en las normas EG-2013 y EM-2016. Al comparar los resultados obtenidos, se determinó que la estabilidad de la mezcla asfáltica convencional fue 1389.4 kg mientras que la mezcla modificada con polímeros SBS fue 1 921.4 kg una diferencia de 38.28%. Es decir, que el modificado tiene la capacidad de resistir desplazamientos y deformaciones bajo tráficos pesados. Asimismo estos resultados influyen en la resistencia del daño inducido por humedad presentando un buen comportamiento de un incremento de TSR 8.85% con respecto al convencional. Esto indica que la susceptibilidad a la humedad mínima. Por lo tanto la incorporación de polímeros SBS a la mezcla asfáltica convencional, mejora notablemente sus propiedades físicas y mecánicas, así disminuir fallas comunes en pavimentos flexibles producidos por los efectos del clima y tráficos de cargas pesadas

Kinematics of individual muscle units in natural contractions measured in vivo using ultrafast ultrasound

Objective. The study of human neuromechanical control at the motor unit (MU) level has predominantly focussed on electrical activity and force generation, whilst the link between these, i.e. the muscle deformation, has not been widely studied. To address this gap, we analysed the kinematics of muscle units in natural contractions. Approach. We combined high-density surface electromyography (HDsEMG) and ultrafast ultrasound (US) recordings, at 1000 frames per second, from the tibialis anterior muscle to measure the motion of the muscular tissue caused by individual MU contractions. The MU discharge times were identified online by decomposition of the HDsEMG and provided as biofeedback to 12 subjects who were instructed to keep the MU active at the minimum discharge rate (9.8 ± 4.7 pulses per second; force less than 10% of the maximum). The series of discharge times were used to identify the velocity maps associated with 51 single muscle unit movements with high spatio-temporal precision, by a novel processing method on the concurrently recorded US images. From the individual MU velocity maps, we estimated the region of movement, the duration of the motion, the contraction time, and the excitation–contraction (E–C) coupling delay. Main results. Individual muscle unit motions could be reliably identified from the velocity maps in 10 out of 12 subjects. The duration of the motion, total contraction time, and E–C coupling were 17.9 $\pm$ 5.3 ms, 56.6 $\pm$ 8.4 ms, and 3.8 $\pm$ 3.0 ms (n = 390 across ten participants). The experimental measures also provided the first evidence of muscle unit twisting during voluntary contractions and MU territories with distinct split regions. Significance. The proposed method allows for the study of kinematics of individual MU twitches during natural contractions. The described measurements and characterisations open new avenues for the study of neuromechanics in healthy and pathological conditions

Histological changes in HCV antibody–positive, HCV RNA–negative subjects suggest persistent virus infection

It is unclear whether hepatitis C virus (HCV) has been eradicated or persists at a low level in HCV antibody–positive HCV RNA–negative individuals. The natural history and liver histology are not well characterized. One hundred seventy-two HCV antibody–positive, serum HCV RNA–negative patients underwent diagnostic liver biopsy between 1992 and 2000 and were followed a median 7 years (range, 5–12). Patients with any possible cause of liver injury other than HCV were excluded. A single histopathologist scored sections using Ishak criteria. Characterization of the inflammatory infiltrate in selected cases used a novel semiquantitative technique and compared with HCV RNA–positive patients and healthy controls. One hundred two patients were excluded because of a risk factor for liver injury other than HCV. Seventy patients met the study criteria; four (5.7%) became HCV RNA–positive during follow-up. Sixty-six cases remained HCV RNA–negative; five (7.5%) had a normal liver biopsy; 54 (82%) had fibrosis (stage 2 or 3 in 16 (24%)). Nonviremic cases revealed expanded portal tracts (P < 0.05), with fewer CD4+ (P < 0.05) and more CD8+ cells (P < 0.05) than healthy controls, but were indistinguishable from HCV RNA–positive cases for these parameters. Lobular CD4 staining, absent in healthy controls, was noted in both HCV RNA–negative and –positive cases and was more marked in the latter (P < 0.05) with a sinusoidal lining cell distribution. Conclusion: Nonviremic HCV antibody–positive patients have a liver biopsy that is usually abnormal. Fibrosis was present in most with similar inflammatory infiltrate to viremic cases. The presence of a CD8+ rich inflammatory infiltrate suggests an ongoing immune response in the liver, supporting the view that HCV may persist in the liver in the majority of HCV RNA–negative cases. (Hepatology 2008;48;1737-1745.

Angiotensin-(1–7) infusion is associated with increased blood pressure and adverse cardiac remodelling in rats with subtotal nephrectomy

ACE (angiotensin-converting enzyme) 2 is expressed in the heart and kidney and metabolizes Ang (angiotensin) II to Ang-(1–7) a peptide that acts via the Ang-(1–7) or mas receptor. The aim of the present study was to assess the effect of Ang-(1–7) on blood pressure and cardiac remodelling in a rat model of renal mass ablation. Male SD (Sprague–Dawley) rats underwent STNx (subtotal nephrectomy) and were treated for 10 days with vehicle, the ACE inhibitor ramipril (oral 1 mg·kg−1 of body weight·day−1) or Ang-(1–7) (subcutaneous 24 μg·kg−1 of body weight·h−1) (all n = 15 per group). A control group (n = 10) of sham-operated rats were also studied. STNx rats were hypertensive (P<0.01) with renal impairment (P<0.001), cardiac hypertrophy (P<0.001) and fibrosis (P<0.05), and increased cardiac ACE (P<0.001) and ACE2 activity (P<0.05). Ramipril reduced blood pressure (P<0.01), improved cardiac hypertrophy (P<0.001) and inhibited cardiac ACE (P<0.001). By contrast, Ang-(1–7) infusion in STNx was associated with further increases in blood pressure (P<0.05), cardiac hypertrophy (P<0.05) and fibrosis (P<0.01). Ang-(1–7) infusion also increased cardiac ACE activity (P<0.001) and reduced cardiac ACE2 activity (P<0.05) compared with STNx-vehicle rats. Our results add to the increasing evidence that Ang-(1–7) may have deleterious cardiovascular effects in kidney failure and highlight the need for further in vivo studies of the ACE2/Ang-(1–7)/mas receptor axis in kidney disease

Monitoring quality of care in hepatocellular carcinoma: A modified delphi consensus

Although there are several established international guidelines on the management of hepatocellular carcinoma (HCC), there is limited information detailing specific indicators of good quality care. The aim of this study was to develop a core set of quality indicators (QIs) to underpin the management of HCC. We undertook a modified, two-round, Delphi consensus study comprising a working group and experts involved in the management of HCC as well as consumer representatives. QIs were derived from an extensive review of the literature. The role of the participants was to identify the most important and measurable QIs for inclusion in an HCC clinical quality registry. From an initial 94 QIs, 40 were proposed to the participants. Of these, 23 QIs ultimately met the inclusion criteria and were included in the final set. This included (a) nine related to the initial diagnosis and staging, including timing to diagnosis, required baseline clinical and laboratory assessments, prior surveillance for HCC, diagnostic imaging and pathology, tumor staging, and multidisciplinary care; (b) thirteen related to treatment and management, including role of antiviral therapy, timing to treatment, localized ablation and locoregional therapy, surgery, transplantation, systemic therapy, method of response assessment, and supportive care; and (c) one outcome assessment related to surgical mortality. Conclusion: We identified a core set of nationally agreed measurable QIs for the diagnosis, staging, and management of HCC. The adherence to these best practice QIs may lead to system-level improvement in quality of care and, ultimately, improvement in patient outcomes, including survival

ACE I/D Gene Polymorphism Can't Predict the Steroid Responsiveness in Asian Children with Idiopathic Nephrotic Syndrome: A Meta-Analysis

The results from the published studies on the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and the treatment response to steroid in Asian children with idiopathic nephrotic syndrome (INS) is still conflicting. This meta-analysis was performed to evaluate the relation between ACE I/D gene polymorphism and treatment response to steroid in Asian children and to explore whether ACE D allele or DD genotype could become a predictive marker for steroid responsiveness. = 0.85; respectively), however, the result for the association of II genotype with SRNS risk was not stable.Our results indicate that D allele or DD homozygous can't become a significant genetic molecular marker to predict the treatment response to steroid in Asian children with INS

Eight weeks of Paritaprevir/r/Ombitasvir + Dasabuvir in HCV genotype 1b with mild‐moderate fibrosis: Results from a real‐world cohort

[Background & Aims] The interferon‐free regimen paritaprevir/ritonavir, ombitasvir + dasabuvir (PTV /r/OBV /DSV ) has shown high efficacy in patients with hepatitis C virus (HCV ) genotype 1b infection when administered for 8 or 12 weeks, but data regarding the 8‐week treatment are scarce. The aim of our study was to assess the efficacy and safety of the 8‐week administration of PTV /r/OBV /DSV in a real‐world cohort.[Methods] We performed a multicentre observational study from Spanish Hepa‐C database including patients receiving 8 weeks of PTV /r/OBV /DSV (October 2016‐November 2017). Those with advanced fibrosis, with non‐genotype 1b or who were treatment‐experienced were excluded.[Results] A total of 211 patients were registered from 23 Spanish centres; eleven were excluded. At baseline, 42.5% (n = 85) were male, median (range) age was 57 (23‐86), ALT was 45 (11‐494) IU/mL, viral load was 6.1 (3.3‐8.2) log10 IU/mL, and 74.5% had mild liver fibrosis (F0‐F1) and 25.5% moderate fibrosis (F2). At the end of treatment (EOT ), HCV viral load was undetectable in 100% (200/200). Seven patients relapsed after treatment discontinuation. Sustained virological response (SVR 12) rates by intention‐to‐treat analysis were 96% (192/200). Regarding treatment safety, 2 patients developed ALT elevation >5x ULN, but there were no treatment discontinuations. One patient died 7 weeks after EOT.[Conclusion] Treatment with PTV/r/OBV/DSV in genotype 1b‐infected treatment‐naive patients with mild‐moderate fibrosis shows excellent efficacy and safety in real life, similarly to clinical trials. Clinicaltrials.gov, number: NCT 03122132.JAC has received a grant from Instituto de Salud Carlos III, Ministerio de Economía y Competitividad (PI14/00540), co‐funded by Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea, Una manera de hacer Europa.Peer reviewe

TNFα-Induced Apoptosis Enabled by CCN1/CYR61: Pathways of Reactive Oxygen Species Generation and Cytochrome c Release

Although TNFα is a strong inducer of apoptosis, its cytotoxicity in most normal cells in vitro requires blockade of NFκB signaling or inhibition of de novo protein synthesis, typically by the addition of cycloheximide. However, several members of CCN (CYR61/CTGF/NOV) family of extracellular matrix proteins enable TNFα-dependent apoptosis in vitro without inhibiting NFκB or de novo protein synthesis, and CCN1 (CYR61) is essential for optimal TNFα cytotoxicity in vivo. Previous studies showed that CCN1 unmasks the cytotoxicity of TNFα by binding integrins αvβ5, α6β1, and the cell surface heparan sulfate proteoglycan syndecan 4 to induce the accumulation of a high level of reactive oxygen species (ROS), leading to a biphasic activation of JNK necessary for apoptosis. Here we show for the first time that CCN1 interacts with the low density lipoprotein receptor-related protein 1 (LRP1) in a protein complex, and that binding to LRP1 is critical for CCN1-induced ROS generation and apoptotic synergism with TNFα. We also found that neutral sphingomyelinase 1 (nSMase1), which contributes to CCN1-induced ROS generation, is required for CCN1/TNFα-induced apoptosis. Furthermore, CCN1 promotes the activation of p53 and p38 MAPK, which mediate enhanced cytochrome c release to amplify the cytotoxicity of TNFα. By contrast, LRP1, nSMase1, p53, and p38 MAPK are not required when TNFα-dependent apoptosis is facilitated by the presence of cycloheximide, indicating that they function in the CCN1 signaling pathway that converges with TNFα-induced signaling events. Since CCN1/CYR61 is a physiological regulator of TNFα cytotoxicity at least in some contexts, these findings may reveal important mediators of TNFα-induced apoptosis in vivo and identify potential therapeutic targets for thwarting TNFα-dependent tissue damage