Un modelo Casi Ideal de Demanda de Combustibles para la Industria de Transporte

Este paper utilizando el Modelo Casi Ideal de Demanda (AIDS) por medio de ecuaciones aparentemente no relacionadas para la industria de combustibles en el sector transporte en Colombia, analiza las elasticidades precio de la demanda, precio cruzada de la demanda y gasto de la demanda de la Gasolina motor, Diesel y Gas Natural Vehicular (GNV), dada la recomposición que ha presentado esta industria entre el 2003 y 2012, con el objetivo de determinar si estos combustibles se comportan como sustitutos o complementarios y se trata de bienes necesarios o no. Los principales resultados indican que la elasticidad precio de la demanda de la Gasolina y el Diesel son bienes inelásticos, mientras que el GNV se comporta como un bien elástico. Por su parte, por medio de la elasticidad precio cruzada de la demanda, se encuentra que solo el Diesel y el GNV se comportan como bienes sustitutos, mientras que para el resto de relaciones (Gasolina-Diesel y Gasolina- GNV) se observa un comportamiento de complementariedad. Además desde la elasticidad gasto de la demanda se encontró que la Gasolina y el Diesel se comportan como bienes normales, mientras que el GNV resulta ser un bien inferior.This article presents an Almost Ideal Demand System (AIDS) for different types of fuels in Colombia, focusing specifically on the transport industry. Estimates of price, expenditure and cross elasticities are computed using a Seemingly Unrelated Regressions (SUR) model and based on 10 years observations (2003-2012). Results show that diesel and regular gas behave as inelastic goods while natural gas is more elastic. Also, diesel fuels and natural gas seem to behave as substitutes while there’s a complementary relation among the others (regular gas-Diesel; regular fuels-Natural Gas). Regarding the expenditures elasticities, this paper concludes that regular gas and diesel behave as normal goods while natural gas seems be an inferior type of fuel for the transport sector

Thyrotoxicosis Following Fine-Needle Aspiration Biopsy of A Thyroid Nodule: Case Report

Abstract Fine-needle aspiration biopsy (FNAB) is a simple and generally safe office-based procedure that accurately and cost-effectively improves the diagnostic investigation of nonfunctioning thyroid nodules. Thyrotoxicosis following FNA has been rarely described in the medical literature. A case of post aspiration thyrotoxicosis is described here with the intent of increasing awareness of this likely underreported complication of FNAB. Key works

Optimization of autohydrolysis conditions to extract antioxidant phenolic compounds from spent coffee grounds

Autohydrolysis, which is an eco-friendly technology that employs only water as extraction solvent, was used to extract antioxidant phenolic compounds from spent coffee grounds (SCG). Experimental assays were carried out using different temperatures (160 to 200 °C), liquid/solid ratios (5 to 15 ml/g SCG) and extraction times (10 to 50 min) in order to determine the conditions that maximize the extraction results. The optimum conditions to produce extracts with high content of phenolic compounds (40.36 mg GAE/g SCG) and high antioxidant activity (FRAP = 69.50 mg Fe(II)/g SCG, DPPH = 28.15 mg TE/g SCG, ABTS = 31.46 mg TE/g SCG, and TAA = 66.21 mg -TOC/g SCG) consisted in using 15 ml water/g SCG, at 200 °C during 50 min. Apart from being a green technology, autohydrolysis under optimized conditions was demonstrated to be an efficient method to extract antioxidant phenolic compounds from SCG.This work was supported by the Science and Technology Foundation of Portugal (FCT - grant SFRH/BD/80948/2011); the Strategic Project PEst-OE/EQB/LA0023/2013; and the Project “Bio-Ind -Biotechnology and Bioengineering for improved Industrial and Agro-Food processes”, REF. NORTE-07-0124-FEDER-000028 cofunded by the Programa Operacional Regional do Norte (ON.2 e O Novo Norte), QREN, FEDER

Anomalous reactivity of supported V2O5 nanoparticles for propane oxidative dehydrogenation: influence of the vanadium oxide precursor

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The oxidative dehydrogenation (ODH) of propane to propylene by supported vanadia catalysts has received much attention in recent years, but different reactivity trends have been reported for this catalytic reaction system. In the present investigation, the origin of these differing trends are investigated with synthesis of supported V/SiO2, V/TiO2, and V/Al2O3 catalysts prepared with three different vanadium oxide precursors (2-propanol/vanadyl triisopropoxide [VO(O-Pri)3] (VTI), oxalic acid/ammonium metavanadate [NH4VO3] (AMV), and toluene/vanadyl acetylacetonate [VO(C5H7O2)2] (VAA)) in order to elucidate the influence of the precursor on supported vanadia phase and propane ODH activity. In situ Raman spectroscopy revealed that the choice of vanadium precursor does not affect the dispersion of the supported vanadium oxide phase below 4 V nm−2 (0.5 monolayer coverage), where only isolated and oligomeric surface VO4 species are present, and only the AMV precursor favors crystalline V2O5 nanoparticle (NP) formation below monolayer coverage (8 V nm−2). The propane ODH specific reactivity trend demonstrated that there is no significant difference in TOF for the isolated and oligomeric surface VO4 sites. Surprisingly, V2O5 NPs in the ∼1–2 nm range exhibit anomalously high propane ODH TOF values for the supported vanadia catalysts. This was found for all supported vanadium oxide catalysts examined. This comparative study with different V-precursors and synthesis methods and oxide supports finally resolves the debate in the catalysis literature about the dependence of TOF on the surface vanadium density that is related to the unusually high reactivity of small V2O5 NPs.DFG, SFB 546, Struktur, Dynamik und Reaktivität von Übergangsmetalloxid-Aggregate

Making Strides: State of the Practice of Pedestrian Forecasting in Regional Travel Models

Much has changed in the 30 years since non-motorized modes were first included in regional travel demand models. As interest in understanding behavioral influences on walking and policies requiring estimates of walking activity increase, it is important to consider how pedestrian travel is modeled at a regional level. This paper evaluates the state of the practice of modeling walk trips among the largest 48 metropolitan planning organizations (MPOs) and assesses changes made over the last 5 years. By reviewing model documentation and responses to a survey of MPO modelers, this paper summarizes current practices, describes six pedestrian modeling frameworks, and identifies trends. Three-quarters (75%) of large MPOs now model non-motorized travel, and over two-thirds (69%) of those MPOs distinguish walking from bicycling; these percentages are up from nearly two-thirds (63%) and one-half (47%), respectively, in 2012. This change corresponds with an increase in the deployment of activity-based models, which offer the opportunity to enhance pedestrian modeling techniques. The biggest barrier to more sophisticated models remains a lack of travel survey data on walking behavior, yet some MPOs are starting to overcome this challenge by oversampling potential active travelers. Decision-makers are becoming more interested in analyzing walking and using estimates of walking activity that are output from models for various planning applications. As the practice continues to mature, the near future will likely see smaller-scale measures of the pedestrian environment, more detailed zonal and network structures, and possibly even an operational model of pedestrian route choice

Valorization of passion fruit stalk by the preparation of cellulose nanofibers and immobilization of trypsin

Fibers from passion fruit stalks were first recovered with a pulping and bleaching process. Two mechanical treatments were further applied to the fibers, homogenization (with and without ultrasound), and blender application. The effect of those treatments on fibers was evaluated. The chemical composition of the different stages of fibers undergoing treatment were measured according to TAPPI standards and were also analyzed by SEM, FTIR, and XRD. Trypsin was immobilized by adsorption and by covalent binding. The biocatalyst support-trypsin was evaluated in terms of immobilization yield, retention, and enzymatic activity. The experimental results demonstrated that the final cellulose concentration in the fibers was 44 % higher than that in the raw stalks. The cellulose nanofibers obtained by homogenization presented a size distribution between 20200 nm, and the application of ultrasound did not show a significant effect on size (between 50 to 300 nm). Trypsin immobilized using glycidol presented an immobilization yield of 67 % and presented higher retention and enzymatic activity (1.17±0.05 U/mg protein and 44.0±2.0 %, respectively). These results show that passion fruit stalks can be successfully used as a source of cellulose nanofibers and also can be used as carriers for the immobilization of trypsin.The authors acknowledge the financial support of Universidad Nacional de Colombia (Hermes code project 34573), COLCIENCIAS call 727-2015 National Doctorates. FONTAGRO (ATN/RF-16111-RG Productividad y Competitividad Frutícola Andina), and Erasmus+Programme Key Action 1. This work was also supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of the UID/BIO/04469/2020 unit and by the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Sporadic calcitonin-negative medullary thyroid carcinoma is not more aggressive than its classic counterpart: case report and review of the literature

Objective: medullary thyroid carcinoma (MTC) with normal serum basal calcitonin (calcitonin-negative MTC) is uncommon. The exact mechanism for this paradox is unclear. It has been suggested that the loss of ability to secrete calcitonin is due to tumor cell dedifferentiation and may confer a worse prognosis. Methods: we describe a 45-year-old woman with a sporadic 4.5-cm well-differentiated MTC, who despite having normal preoperative serum basal calcitonin and poor calcitonin immunostaining in tumor cells, remains in remission 5 years after total thyroidectomy with bilateral central neck dissection. Out of the 20 patients with calcitonin-negative MTC reported to date, we include 16 patients with clinical disease at presentation to determine if they fare worse than their classic MTC counterparts. We try to correlate the extent of calcitonin immunostaining with the degree of tumor differentiation to determine if poor tumor calcitonin immunoreactivity is an indicator of tumor cell dedifferentiation. Results: Seven and 9 patients with calcitonin-negative MTC had poorly-differentiated and well-differentiated tumors, respectively. Four patients in the former group died from metastatic MTC within 3 years of the diagnosis. The status of the 2 living patients with known follow-up information was one with N1 disease and one in remission. In the well-differentiated group, 2 patients had N1M1 disease and 7 patients were in remission. According to the number of tumor cells immunoreactive to calcitonin, the 15 patients with known data were classified in 3 groups: 1+ group (only few tumor cells stained weakly for calcitonin), 7 patients; 2+ group (many tumor cells stained focally for calcitonin), 2 patients; and 3+ group (most tumor cells stained strongly for calcitonin), 6 patients. The level of calcitonin immunoreactivity did not correlate with the patient’s clinical status. Conclusion: the degree of tumor differentiation is a far better predictor of outcome than the extent of calcitonin immunoreactivity and poor tumor calcitonin staining is not necessarily an indicator of tumor cell dedifferentiation

El síndrome infertilidad del verano en cerdas.

Se realizó un estudio epidemiológico retrospectivo sobre el síndrome infertilidad del verano (SIV) en cerdas de cría de Somerset, Inglaterra, con el fin de: conocer la epidemiología del síndrome, evaluar la importancia de factores meteorológicos medio-ambientales en su causalidad, y producir recomendaciones prácticas para su prevención y control. Se analizaron registros de 5708 cerdas de cría, mediante el programa EPI-INFO, datos que corresponderían a 19 meses de servicios, partos y otros eventos reproductivos. Se encontró que el SIV se caracteriza por: retorno del estro después de los servicios efectuados en los meses de verano, bajas tasas de partos y tasas altas de mortalidad fetal y de momificación. La tasa general de repeticiones de servicios fue más alta para nulíparas que para multíparas, y la mayoría de las repeticiones ocurrieron entre los dias 18 y 24 después del servicio. Adicionalmente se estableció que el calor, como factor de estrés, ocasiona el 50 por ciento del problema y que ese factor afecta más las tasas de repeticiones y de partos de las multíparas que de las nulíparas, mientras que el efecto del fotoperíodo es mayor sobre la tasa de partos de las nulíparas que sobre las de las multíparas. Se concluyó que hay otros factores que afectan la reproducción e interactuan durante todo el año, y que el efecto del calor y del fotoperíodo es aditivo

Extraction of antioxidant phenolic compounds by autohydrolysis of spent coffee grounds

The extraction of antioxidant phenolic compounds from spent coffee grounds (SCG) was studied. Experimental assays were carried out by the autohydrolysis technique and the effect of the process variables temperature, water/SCG ratio and extraction time on the amount of phenolic compounds and antioxidant activity of the produced extracts was evaluated. The variables were combined according to a 23 central composite design. The statistical model revealed that the optimum condition to produce extracts with high content of phenolic compounds (35.07 mg GAE/g SCG) and antioxidant activity (FRAP = 0.25 mmol Fe(II)/g SCG, DPPH = 121.7 μmol TE/g SCG, ABTS = 130.0 μmol TE/g SCG, TAA = 64.17 mg α-TOC/g SCG) was achieved when maximizing the process variables (temperature = 200 °C, ratio = 15 ml/g and time = 50 min)