Search results for "Economics"
showing 10 items of 14389 documents
Emotions and Digital Delivery Platforms
2021
From the global spread of the infectious disease COVID-19, in Argentina as in other states worldwide, health measures, social emergency, economic and public order measures were taken. One of the main and earliest measures of social order in the face of this disease was the delimitation of a period of population isolation, known as preventive and obligatory social isolation. The compulsory social isolation generated unprecedented growth in the demand for services to the platform economies in Argentina in general and in Buenos Aires in particular, causing the platform delivery activity to be conceived as an essential activity. The purpose of the writing is to explore the configuration of a ce…
A Magnetohydrodynamic Auxiliary Propulsion system for docking assistance of autonomous vehicle
2016
In this article we present an approach to the description of Magnetohydrodynamic Auxiliary Propulsion system for docking assistance of autonomous vehicle. Preliminarily, an analytical model which includes an electromagnetic model and a thermal model is presented. Successively, in order to move beyond the analytical model, a 3-D MHD modeling tool and a Runge Kutta method based solver are presented and they are used to investigate an alternative MHD solutions. Some numerical analysis are given
The helicoidal magnetic generator
2016
Recently helicoidal generator for the exploitation of sea wave energy has been proposed. This device can convert both the vertical and rotational movement of seawaves. The electrical energy generated by such a device must be converted and conditioned in order to match the instantaneous utility requirements and a power link from the sea to an interconnection is needed. In this paper, the authors propose a mathematical model of this device and preliminarily present a prototype of the machine.
Acoustic vibrations of monoclinic zirconia nanocrystals
2011
International audience; Polarized low-frequency Raman spectra originating from confined acoustic vibrations are reported for monoclinic ZrO2 nanoparticles with a narrow size distribution synthesized from a continuous supercritical water process. The monoclinic lattice structure is taken into account for the interpretation of the spectra by comparing with isotropic and anisotropic continuum elasticity calculations for monodomain nanocrystals. The various mechanisms leading to the broadening of the Raman peaks are discussed. We demonstrate that an accurate determination of the size distribution of the nanoparticles is possible using the Raman peak due to the fundamental breathing vibration wh…
Superiority of Optimized Portfolios to Naive Diversification: Fact or Fiction?
2017
Abstract DeMiguel, Garlappi, and Uppal (2009) conducted a highly influential study where they demonstrated that none of the optimized portfolios consistently outperformed the naive diversification. This result triggered a heated debate within the academic community on whether portfolio optimization adds value. Nowadays several studies claim to defend the value of portfolio optimization. The commonality in all these studies is that various portfolio optimization methods are implemented using the datasets generously provided by Kenneth French and the performance is measured by means of the Sharpe ratio. This paper aims to provide a cautionary note regarding the use of Kenneth French datasets …
Optimal Dynamic Portfolio Risk Management
2016
Numerous econometric studies report that financial asset volatilities and correlations are time-varying and predictable. Over the past decade, this knowledge has stimulated increasing interest in various dynamic portfolio risk control techniques. The two basic types of risk control techniques are: risk control across assets and risk control over time. At present, the two types of risk control techniques are not implemented simultaneously. There has been surprisingly little theoretical study of optimal dynamic portfolio risk management. In this paper, the author fills this gap in the literature by formulating and solving the multi-period portfolio choice problem. In terms of dynamic portfoli…
Analysis of salivary detection of P16INK4A and RASSF1A promoter gene methylation and its association with oral squamous cell carcinoma in a Colombian…
2019
Background Epigenetic factors play a fundamental role in the etiopathogenesis of oral squamous cell carcinoma (OSCC). This study evaluated if salivary detection of P16INK4A/RASSF1A gene promoter methylation might be linked to the clinical/histological features of OSCC in a Colombian population. Material and Methods Methylation-specific polymerase chain reaction (MSP-PCR) was used to detect the methylation frequency of P16INK4A/RASSF1A genes in DNA obtained from whole saliva collected of 40 healthy controls (HC) and 43 OSCC patients. Determination of the clinical performance of MSP-PCR assay was based on standard algorithms derived from two-way contingency table analysis. The association of …
Potential impacts of a future Nordic bioeconomy on surface water quality
2020
AbstractNordic water bodies face multiple stressors due to human activities, generating diffuse loading and climate change. The ‘green shift’ towards a bio-based economy poses new demands and increased pressure on the environment. Bioeconomy-related pressures consist primarily of more intensive land management to maximise production of biomass. These activities can add considerable nutrient and sediment loads to receiving waters, posing a threat to ecosystem services and good ecological status of surface waters. The potential threats of climate change and the ‘green shift’ highlight the need for improved understanding of catchment-scale water and element fluxes. Here, we assess possible bio…
Sun-induced chlorophyll fluorescence III: benchmarking retrieval methods and sensor characteristics for proximal sensing
2019
[EN] The interest of the scientific community on the remote observation of sun-induced chlorophyll fluorescence (SIF) has increased in the recent years. In this context, hyperspectral ground measurements play a crucial role in the calibration and validation of future satellite missions. For this reason, the European cooperation in science and technology (COST) Action ES1309 OPTIMISE has compiled three papers on instrument characterization, measurement setups and protocols, and retrieval methods (current paper). This study is divided in two sections; first, we evaluated the uncertainties in SIF retrieval methods (e.g., Fraunhofer line depth (FLD) approaches and spectral fitting method (SFM))…
Modelling and Analysis of Flow Rate and Pressure Head in Pipelines
2019
Currently, various approaches with several utilities are proposed to identify damage in the pipeline. The pipeline system is modeled in the form of a distributed parameter system, such that the state space related to the distributed parameter system contains infinite dimension. In this paper, a novel technique is proposed to analyze and model the flow in the pipeline. Important theorems are proposed for testing the observability as well as controllability of the proposed model.