El marco natural de Chile: su diversidad de paisajes

Se exponen brevemente las características climáticas, geomorfológicas y fitogeográficas de Chile Sudamericano, identificando unidades territoriales caracterizadas por cada una de las variables citadas con el fin de destacar la amplia gama de paisajes desarrollados en el territorio

Comparison of self-administered survey questionnaire responses collected using mobile apps versus other methods

Background: Self-administered survey questionnaires are an important data collection tool in clinical practice, public health research and epidemiology. They are ideal for achieving a wide geographic coverage of the target population, dealing with sensitive topics and are less resource intensive than other data collection methods. These survey questionnaires can be delivered electronically, which can maximise the scalability and speed of data collection while reducing cost. In recent years, the use of apps running on consumer smart devices (i.e., smartphones and tablets) for this purpose has received considerable attention. However, variation in the mode of delivering a survey questionnaire could affect the quality of the responses collected. Objectives: To assess the impact that smartphone and tablet apps as a delivery mode have on the quality of survey questionnaire responses compared to any other alternative delivery mode: paper, laptop computer, tablet computer (manufactured before 2007), short message service (SMS) and plastic objects. Search methods: We searched MEDLINE, EMBASE, PsycINFO, IEEEXplore, Web of Science, CABI: CAB Abstracts, Current Contents Connect, ACM Digital, ERIC, Sociological Abstracts, Health Management Information Consortium, the Campbell Library and CENTRAL. We also searched registers of current and ongoing clinical trials such as ClinicalTrials.gov and the World Health Organization (WHO)International Clinical Trials Registry Platform. We also searched the grey literature in OpenGrey, Mobile Active and ProQuest Dissertation & Theses. Lastly, we searched Google Scholar and the reference lists of included studies and relevant systematic reviews. We performed all searches up to 12 and 13 April 2015. Selection criteria: We included parallel randomised controlled trials (RCTs), crossover trials and paired repeated measures studies that compared the electronic delivery of self-administered survey questionnaires via a smartphone or tablet app with any other delivery mode. We included data obtained from participants completing health-related self-administered survey questionnaire, both validated and non-validated. We also included data offered by both healthy volunteers and by those with any clinical diagnosis. We included studies that reported any of the following outcomes: data equivalence; data accuracy; data completeness; response rates; differences in the time taken to complete a survey questionnaire; differences in respondent’s adherence to the original sampling protocol; and acceptability to respondents of the delivery mode. We included studies that were published in 2007 or after, as devices that became available during this time are compatible with the mobile operating system (OS) framework that focuses on apps. Data collection and analysis: Two review authors independently extracted data from the included studies using a standardised form created for this systematic review in REDCap. They then compared their forms to reach consensus. Through an initial systematic mapping on the included studies, we identified two settings in which survey completion took place: controlled and uncontrolled. These settings differed in terms of (i) the location where surveys were completed, (ii) the frequency and intensity of sampling protocols, and (iii) the level of control over potential confounders (e.g., type of technology, level of help offered to respondents).We conducted a narrative synthesis of the evidence because a meta-analysis was not appropriate due to high levels of clinical and methodological diversity. We reported our findings for each outcome according to the setting in which the studies were conducted. Main results: We included 14 studies (15 records) with a total of 2275 participants; although we included only 2272 participants in the final analyses as there were missing data for three participants from one included study. Regarding data equivalence, in both controlled and uncontrolled settings, the included studies found no significant differences in the mean overall scores between apps and other delivery modes, and that all correlation coefficients exceeded the recommended thresholds for data equivalence. Concerning the time taken to complete a survey questionnaire in a controlled setting, one study found that an app was faster than paper, whereas the other study did not find a significant difference between the two delivery modes. In an uncontrolled setting, one study found that an app was faster than SMS. Data completeness and adherence to sampling protocols were only reported in uncontrolled settings. Regarding the former, an app was found to result in more complete records than paper, and in significantly more data entries than an SMS-based survey questionnaire. Regarding adherence to the sampling protocol, apps may be better than paper but no different from SMS. We identified multiple definitions of acceptability to respondents, with inconclusive results: preference; ease of use; willingness to use a delivery mode; satisfaction; effectiveness of the system informativeness; perceived time taken to complete the survey questionnaire; perceived benefit of a delivery mode; perceived usefulness of a delivery mode; perceived ability to complete a survey questionnaire; maximum length of time that participants would be willing to use a delivery mode; and reactivity to the delivery mode and its successful integration into respondents’ daily routine. Finally, regardless of the study setting, none of the included studies reported data accuracy or response rates. Authors’ conclusions: Our results, based on a narrative synthesis of the evidence, suggest that apps might not affect data equivalence as long as the intended clinical application of the survey questionnaire, its intended frequency of administration and the setting in which it was validated remain unchanged. There were no data on data accuracy or response rates, and findings on the time taken to complete a self-administered survey questionnaire were contradictory. Furthermore, although apps might improve data completeness, there is not enough evidence to assess their impact on adherence to sampling protocols. None of the included studies assessed how elements of user interaction design, survey questionnaire design and intervention design might influence mode effects. Those conducting research in public health and epidemiology should not assume that mode effects relevant to other delivery modes apply to apps running on consumer smart devices. Those conducting methodological research might wish to explore the issues highlighted by this systematic review

ON THE LOCALIZED PHYSICAL EXERGY DISAGGREGATION FOR DISSIPATIVE COMPONENT ISOLATION IN THERMOECONOMICS

Thermoeconomics is a discipline that connects Thermodynamics and Economics concepts, usually used for rational cost allocation to the final products of a thermal plant, by means of a model that describes the cost formation process of the overall system. Generally, exergy or monetary costs of the external resources are distributed to the final products. Exergy is the thermodynamic magnitude used in thermoeconomics and the physical exergy disaggregation has been introduced in thermoeconomics as alternatives for the isolation of the dissipative components and residues allocation. For plants with dissipative equipment, such as condenser or valve, the productive diagram, based on total exergy (E Model), need to merge this dissipative equipment with other productive components. In order to isolate the condenser, the productive diagram must use, at least, the H&S Model and to isolate the valve, the UFS Model has to be considered.Both disaggregation models greatly increase the thermoeconomic modeling complexity. Bearing this in mind, this work aims to evaluate the advantages of combining the E Model with these other models in order to adequately isolate the dissipative equipment. The plants studied herein are two different steam turbine cogeneration systems, with dissipative components (condenser or valve). The different monetary and exergy unit costs obtained for the two final products of each plant are compared and analyzed.  The results show that localized physical exergy disaggregation for dissipative component isolation in thermoeconomics is feasible, since it reduces the complexity of the productive structure and is also consistent from the point of view of thermodynamics

Hypoxia dictates metabolic rewiring of tumors: implications for chemoresistance

Hypoxia is a condition commonly observed in the core of solid tumors. The hypoxia-inducible factors (HIF) act as hypoxia sensors that orchestrate a coordinated response increasing the pro-survival and pro-invasive phenotype of cancer cells, and determine a broad metabolic rewiring. These events favor tumor progression and chemoresistance. The increase in glucose and amino acid uptake, glycolytic flux, and lactate production; the alterations in glutamine metabolism, tricarboxylic acid cycle, and oxidative phosphorylation; the high levels of mitochondrial reactive oxygen species; the modulation of both fatty acid synthesis and oxidation are hallmarks of the metabolic rewiring induced by hypoxia. This review discusses how metabolic-dependent factors (e.g., increased acidification of tumor microenvironment coupled with intracellular alkalinization, and reduced mitochondrial metabolism), and metabolic-independent factors (e.g., increased expression of drug efflux transporters, stemness maintenance, and epithelial-mesenchymal transition) cooperate in determining chemoresistance in hypoxia. Specific metabolic modifiers, however, can reverse the metabolic phenotype of hypoxic tumor areas that are more chemoresistant into the phenotype typical of chemosensitive cells. We propose these metabolic modifiers, able to reverse the hypoxia-induced metabolic rewiring, as potential chemosensitizer agents against hypoxic and refractory tumor cells

Requerimientos nutricionales de proteina para cabras en gestación.

En el presente experimento se estimaron los requerimientos protéicos en cabras gestantes. Fue desarrollado en la Universidad Federal de Vicosa, M.G. Brasil, con las siguientes condiciones climáticas: altitud de 649 m.s.n.m., temperatura promedio anual de 19 grados centígrados, humedad relativa de 80 por ciento y precipitación anual de 1341 m.m. Los requerimientos de proteina se calcularon a través de la técnica del sacrificio comparativo, y la proteina determinada por el método semi-micro Kjeldahl. La digestibilidad de la proteina de la ración se evaluó por el método de colecta total de heces y orina. Los requerimientos de proteína dietética se determinaron mediante una fórmula en la que se involucra deposición líquida sobre el valor biológico real multiplicado por digestibilidad verdadera y se expresa en porcentaje. Los requerimientos de proteína dietética, en g/día, para la fase inicial de la gestación, fueron 0.5, 8.8 y 27.1, respectivamente, en las gestaciones simples, y en el mismo orden 1.0, 14.2 y 44.3 para gestaciones dobles. Los requerimientos de proteína cruda diaria, en gramos por unidad de tamaño metabólico, calculadas para gestaciones de un feto para los períodos de 0 a 100 y 100 a 140 días, fueron de 0.60 y 1.68, respectivamente. Los valores obtenidos para gestaciones dobles fueron: 0.90 y 2.21 en el mismo períodoCaprinos-Capra hircu

Crecimiento fetal y de otros componentes del útero grávito en cabras mestizas

Existe un ilimitado numera de estudios sobre crecimiento prenatal en caprinos. La información obtenida reviste Importancia en la estimación de requerimientos nutricionales en la fase de gestación Con el objetivo de aportar Información sobre la evolución de los pesos fetales y otros componentes del útero grávido, se realizó el presente estudio en la Universidad Federal de Viscosa, M G , Brasil.Caprinos-Capra hircu