In the SARS-CoV-2 lineage, RNA elements essential for its viral life cycle, including genome replication and gene expression, have been identified. Still, the precise structures and functions of ...these RNA regions in coronaviruses remain poorly understood. This lack of knowledge points out the need for further research to better understand these crucial aspects of viral biology and, in time, prepare for future outbreaks. In this research, the in silico analysis of the cis RNA structures that act in the alpha-, beta-, gamma-, and deltacoronavirus genera has provided a detailed view of the presence and adaptation of the structures of these elements in coronaviruses. The results emphasize the importance of these cis elements in viral biology and their variability between different viral variants. Some coronavirus variants in some groups, depending on the cis element (stem-loop1 and -2; pseudoknot stem-loop1 and -2, and s2m), exhibited functional adaptation. Additionally, the conformation flexibility of the s2m element in the SARS variants was determined, suggesting a coevolution of this element in this viral group. The variability in secondary structures suggests genomic adaptations that may be related to replication processes, genetic regulation, as well as the specific pathogenicity of each variant. The results suggest that RNA structures in coronaviruses can adapt and evolve toward different viral variants, which has important implications for viral adaptation, pathogenicity, and future therapeutic strategies.
(analítico)En Chile, actualmente la población categorizada como jóvenes que ni estudian ni trabajan (conocidos como nini) asciende a cerca de medio millón de personas, lo que presenta un desafío en ...la orientación de estrategias que les permitan insertarse en el mercado del trabajo o continuar sus estudios. Esta investigación tiene por finalidad determinar los factores que influyen en la transición de la escolaridad al trabajo en la población de jóvenes chilenos, por medio de modelos probabilísticos a partir de datos representativos a nivel nacional. Los resultados muestran que son determinantes la pobreza, la existencia de menores en el hogar, el género y la paternidad o maternidad adolescente. Se establecen algunas estrategias y se hace hincapié en continuar el estudio considerando la multitud de factores que están involucrados.
Palabras clave: Desempleo de los jóvenes; transición a la vida activa; jóvenes; mercado de trabajo.
The present work analyzed the concentration of As, Cd, Pb, and Hg in sediment and the Hg concentration in fish muscle from two coastal lagoons in the states of Jalisco (Barra de Navidad Lagoon) and ...Colima (Cuyutlan Lagoon), Mexico. Both lagoons showed relatively low levels of metal contamination and potential health risk compared to other Mexican areas. A non-carcinogenic hazard quotient (HQ) was determined. As (10.7 + or - 1.3 - 25.4 + or - 3.1 microg g.sup.-1) and Pb (42.7 + or - 4.2 - 123.9 + or - 14.7 microg g.sup.-1) concentrations exceeded the permissible levels, otherwise for Hg and Cd were below the limits. The highest total mercury concentration was found in Haemulopsis sp. and Lutjanus sp. with 0.23 and 0.1 microg g.sup.-1 (wet weight) respectively, out of 14 species of fish analyzed that are frequently consumed locally. HQ based on the national daily per capita consumption of fish in Mexico and the consumption of fish associated with fishing communities in Mexico showed an HQs >2, which manifests the vulnerability of these communities to persistent toxic and bioaccumulative contaminants.
•Positive control with a sliding-mode scheme reaches robust stabilization.•The Metzlerian matrices provides robustness properties.•A family of linear systems is controlled in a sliding ...hyperplane.•Robust stabilization of positive systems via positive control.•We prove that the sliding stabilization is optimal in the plane.
In this paper a robust control is proposed for a family of positive and compartmental systems. Sufficient conditions are provided for the stabilization of this kind of systems by using sliding mode theory. The construction of a stabilizing hyperplane with a sliding dynamics is detailed and the feasibility of the method is discussed. The method is illustrated with three examples. The first one is a two-dimensional system which is used only to show the details about the computation, the construction of the stabilizing hyperplane and the robustness of the control. Complementary, the last two are actual interesting cases of biomedical systems and they show potential applications about the stabilization and closed-loop performance. It should be noted that these biomedical systems arise as a current class of dynamical systems with interesting challenges for the process control.
SUMMARY
Biofuels have been shown to be a promising and highly attractive alternative for minimizing the use of fossil fuels, and microalgae have positioned themselves as potential candidates for ...production of lipids and other substances of commercial interest. We briefly review recent advances made in microalgae culture conditions and genetic manipulation for improving lipid yields for biofuel production – with both approaches showing similar yields of triacylglycerides, indicating that more work is required for improving lipid yield and accumulation in algae. Aiming at gaining knowledge of algae genetic manipulation and exploring future use of this information for modifying the lipid biosynthesis pathway, we investigated whether some characteristics of enzymes involved in lipid biosynthesis could relate to lipid yield and accumulation in algae. We made an in silico analysis of amino acid sequence of enzymatic domains and modeled tertiary structure of three proteins involved in the biosynthesis of lipids in microalgae: acetyl‐CoA carboxylase, Acyl‐CoA: diacylglycerol acyltransferase, and glycerol‐3‐phosphate acyltransferase. Our results suggest that, based on primary amino acid sequences and tertiary structure of proteins shared by certain algae, it is likely that these proteins may relate to lipid yield and accumulation, which makes bioinformatics a powerful tool for in silico study of proteins and for selecting genes involved in lipid biosynthesis that could be useful for heterologous transformation in algae with the long term objective of improving their yield, accumulation, and fatty acid composition by genetic engineering.
In the therapy of type 1 diabetes, artificial pancreas (AP) involves the automatic insulin delivery. The control problem in AP has been formulated to regulate glucose into its physiological range ...without accounting for dynamical effects of the delivered insulin. To address this problem, a control scheme to stabilise the insulin is proposed. The method shows that insulin stabilisation is reached and it is further improved while glucose remains into its range. Glucose metabolism is represented by a physiological and compartmental mathematical model, which consists of three interconnected subsystems called glucose, insulin and glucagon subsystems. In particular, the insulin subsystem is a positive linear system, thus it is possible to exploit its properties to propose a stabilisation scheme via positive control. Two approaches are presented: one based on sliding mode theory, and other based on control Lyapunov function theory. Some conditions are stated for the existence of stabilising controllers that improve the stabilisation rate while they take advantage of the cascade structure of the physiological model to maintain glucose into its range. A further application of these schemes is regarding safety of AP, preventing hypoglycaemia and/or hyperinsulinemia induced by a possible overreaction of AP's control schemes.
Background Intraoperative frozen section (FS) often is performed in patients who undergo thyroid lobectomy to determine the need for completion thyroidectomy. At our institution, if FS pathology is ...benign, final pathology is expedited overnight. The aim of this study was to determine the utility of FS and to identify a cost-effective management algorithm for thyroid lobectomy. Methods A retrospective review was performed of patients who underwent thyroid lobectomy between January 2009 and May 2013. Preoperative cytology ranged from “benign” to “suspicious for malignancy.” Clinically significant cancers were defined as >1 cm in size, or multifocal microcarcinomas. Results Of the 192 patients who underwent thyroid lobectomy with FS, FS was suspicious for malignancy in 5 (3%) patients; 1 (0.5%) underwent immediate completion thyroidectomy. On final pathology, 9 (5%) patients had clinically significant cancers and underwent completion thyroidectomy. FS had a sensitivity and positive predictive value of 22% and 40%, respectively, in identifying clinically significant thyroid cancer. Cost of thyroid lobectomy at varying rates of same-day discharge favored thyroid lobectomy without FS but with expedited pathology for all scenarios. Conclusion At our institution, there appears to be limited utility of FS at the time of thyroid lobectomy given the low predictive value for diagnosing a clinically significant thyroid cancer. In patients who are admitted overnight, expedited pathology is slightly less costly and may improve patient quality-of-life and decrease costs by avoiding delayed completion thyroidectomy. Overnight pathology for patients who undergo thyroid lobectomy may achieve modest cost-savings depending on institutional FS results and rates of malignancy.
The aim of this study was to evaluate a new injection-acquisition technique performed using a multirow detector CT scanner for separation of three distinct hepatic circulatory phases (hepatic artery, ...portal venous inflow, hepatic venous) and to determine which of these phases is optimal for detecting hypervascular neoplasm.
Two sequential acquisitions were performed during a single breath-hold followed by a third acquisition beginning 60 sec after injection. Injection-to-scan delay for the first acquisition was the individual patient's circulation time, which was determined by a preliminary mini bolus. The mean attenuation of the upper abdominal aorta, portal vein, and hepatic parenchyma were determined for each imaging pass in 20 patients with cirrhosis and 20 patients without cirrhosis. Tumor-to-liver contrast for hypervascular primary and metastatic neoplasm was evaluated in a different set of 16 cirrhotic patients and nine noncirrhotic patients. Three-dimensional CT arteriograms were obtained from first-pass data.
Three distinct circulatory phases (hepatic artery, portal vein inflow or late arterial, and hepatic venous) were seen in cirrhotic and noncirrhotic patients. Maximum tumor-to-liver contrast for hypervascular primary and metastatic neoplasm occurred during the second pass for both cirrhotic (p < 0.006) and noncirrhotic (p < 0. 001) patients. A three-dimensional hepatic-mesenteric CT arteriogram of normal or anomalous hepatic vessels without venous overlay was obtained from first-pass data in all patients.
Rapid-sequence hepatic helical CT allows selection of the optimal time interval for hypervascular tumor detection. A new paradigm for rapid hepatic CT acquisition-namely, hepatic arterial, portal vein inflow, and hepatic venous phases-is recommended to replace hepatic artery dominant and portal venous phases.
We report our experience with LC for small renal tumors.
Patients who underwent LC at our institution between February 2000 and September 2004 were included in the study. A retrospective chart review ...was done for perioperative and postoperative parameters as well as clinical outcomes.
A total of 65 LCs were performed in 59 patients during the period reviewed. Overall 81 renal tumors were cryoablated. Median patient age was 62 years. Median tumor size was 2.5 cm. Median operative time was 190 minutes. Median estimated blood loss was 50 ml. Median hospital stay was 2 days. Conversion to open surgery occurred in 2 patients. Nephrectomy for bleeding occurred in 1 patient. Median followup was 26.8 months. Two recurrences were identified after LC.
LC is an alterative modality to laparoscopic partial nephrectomy or open partial nephrectomy for small renal tumors. Tumor recurrence rates in the studies published to date are comparable to those of partial nephrectomy, although longer followup is needed.
