Economic growth without welfare. The case of the impact of commodities on the Colombian economy

ABSTRACT Economic growth is not always related to social welfare. Therefore, this paper takes the case of the Colombian economy that has a strong dependence on commodity exploitation to identify the impacts of different commodities such as oil, coffee, coal, and nickel over economic variables. The results show that the increase in prices of commodities generates significant impacts on economic activity in variables such as GDP and investment. Also, there are no significant impacts on variables that provide welfare to individuals as total consumption or the unemployment rate.

Comparative Analysis of GEDI’s Elevation Accuracy from the First and Second Data Product Releases over Inland Waterbodies

Spaceborne LiDAR altimetry has been demonstrated to be an essential source of data for the estimation and monitoring of inland water level variations. In this study, water level estimates from the Global Ecosystem Dynamics Investigation (GEDI) were validated against in situ gauge station records over Lake Geneva for the period between April 2019 and September 2020. The performances of the first and second releases (V1 and V2, respectively) of the GEDI data products were compared, and the effects on the accuracy of the instrumental and environmental factors were analyzed in order to discern the most accurate GEDI acquisitions. The respective influences of five parameters were analyzed in this study: (1) the signal-over-noise ratio (SNR); (2) the width of the water surface peak within the waveform (gwidth); (3) the amplitude of the water surface peak within the waveform (A); (4) the viewing angle of GEDI (VA); and (5) the acquiring beam. Results indicated that all these factors, except the acquiring beam, had an effect on the accuracy of GEDI elevations. Nonetheless, using VA as a filtering criterion was demonstrated to be the best compromise between retained shot count and water level estimation accuracy. Indeed, by choosing the shots with a VA ≤ 3.5°, 74.6% of the shots (after an initial filter) were retained with accuracies similar to choosing A > 400 (46.2% retained shots), SNR > 15 dB (63.3% retained shots), or gwidth < 10 bins (46.5% of retained shots). Finally, the comparison between V1 and V2 elevations showed that V2, overall, provided elevations with a more constant, but higher, bias and fewer deviations to the in situ data than V1. Indeed, by choosing GEDI shots with VA ≤ 3.5°, the unbiased RMSE (ubRMSE) of GEDI elevations was 27.1 cm with V2 (r = 0.66) and 42.8 cm with V1 (r = 0.34). Results also show that the accuracy of GEDI (ubRMSE) does not seem to depend on the beam number and GEDI acquisition dates for the most accurate GEDI acquisitions (VA ≤ 3.5°). Regarding the bias, a higher value was observed with V2, but with lower variability (54 cm) in comparison to V1 (35 cm). Finally, the bias showed a slight dependence on beam GEDI number and strong dependence on GEDI dates.

Controlling magnetic-semiconductor properties of the Si- and Al-doped blue phosphorene monolayer

Doping has been widely employed as an efficient method to diversify the materials properties. In this work, the structural, magnetic, and electronic properties of pristine, aluminum(Al)-, and silicon(Si)-doped blue phosphorene monolayer are investigated using first-principles calculations. Pristine monolayer is a non-magnetic wide gap semiconductor with a band gap of 1.81 eV. The 1Si-doped system is a ferromagnetic semiconductor. However, the magnetism is turned off when increasing the dopant composition with small Si-Si distance. Further separating the dopants recovers step by step the magnetic properties, and an antiferromagnetic(AFM)-ferromagnetic(FM) state transition will take place at large dopants separation. In contrast, Al doping retains the non-magnetic semiconductor behavior of blue phosphorene. However, significant energy gap reduction is achieved, where this parameter exhibits a strong dependence on the dopant concentration and doping configuration. Such control may also induce the indirect-direct gap transition. Our results introduce prospective two-dimensional (2D) materials for applications in spintronic and optoelectronic nano devices, which can be realized and stabilized in experiments as suggested by the calculated formation and cohesive energies.

Analysis of biaxial proportional low-cycle fatigue crack propagation for hull inclined-crack plate based on accumulative plasticity

Fracture failures of ship plates subjected to in-plane biaxial low-cycle fatigue loading are generally the coupling result of accumulative plasticity and biaxial low-cycle fatigue damage. A biaxial low-cycle fatigue crack growth analysis of hull structure that accounts for the accumulative plasticity effect can be more suitable for the actual evaluation of the overall fracture performance of the hull structure in severe sea conditions. An analytical model of biaxial low-cycle fatigue crack propagation with a control parameter for ∆CTOD is presented for hull inclined-crack plate. A test was conducted for cruciform specimens made of Q235 steel with an inclined crack to validate the presented analysis. The biaxial accumulative plasticity behavior and the effects of biaxiality and stress ratios were investigated. The results of this study reveal a strong dependence of biaxial low-cycle fatigue crack propagation on biaxial accumulated plasticity.

Reflection Characteristics of Airy Beams Impinging on Graphene-Substrate Surfaces

In this work, we analytically and numerically investigate the reflection characteristics of the airy beams impinging on graphene-substrate surfaces. The explicit analytical expressions for the electric and magnetic field components of the airy beams reflected from a graphene-substrate interface are derived. The local-field amplitude, Poynting vector, and spin and orbital angular momentum of the reflected airy beams with different graphene structure and beam parameters are presented and discussed. The results show that the reflection properties of the airy beams can be flexibly tuned by modulating the Fermi energy of the graphene and have a strong dependence on the incident angle and polarization state. These results may have potential applications in the modulation of airy beams and precise measurement of graphene structure parameters.

Влияние параллельного слоям магнитного поля на фототок в GaAs/AlAs p-i-n-структурах

The behavior of the photocurrent in GaAs / AlAs p-i-n heterostructures is studied in a magnetic field parallel to the heterolayers in the wavelength range from 395 to 650 nm. A strong dependence of the non-oscillating component of the photocurrent on the radiation wavelength associated with the suppression of the diffusion current by the magnetic field was found. It is shown that the behavior of the oscillating component of the photocurrent in a magnetic field does not depend on the wavelength of light and is determined by the transfer of electrons through the dimensional quantization level in a triangular near-barrier well. It is shown that the suppression of the oscillating component by the magnetic field is due to the smearing of the level in the triangular well due to the motion of electrons parallel to the walls of the well and perpendicular to the magnetic field.

How Environmentally Sustainable Is the Internationalisation of Higher Education? A View from Australia

In a world of increasing awareness of the many drivers of anthropogenic climate change, all of which fall under the larger rubric of global capitalism with its emphasis on profit-making, economic growth, and a strong dependence on fossil fuels, many universities, particularly in developed societies, have proclaimed a staunch commitment to the notion of environmental sustainability. Conversely, the growing emphasis on internationalisation of higher education, particularly in Australia, entails a considerable amount of air travel on the part of university staff, particularly academics but also support staff, and overseas students and occasionally domestic students. Australia is a generally highly affluent country which is situated in the driest inhabited continent and increasingly finds itself functioning as a “canary the coal mine” with respect to the ravages of anthropogenic climate change. Ironically, climate scientists and other observers often refer to various regions, such as the Arctic, low-lying islands, the Andes, and Bangladesh, inhabited by indigenous and peasant peoples as the canaries in the coalmines when it comes to the adverse impacts of anthropogenic climate change. It is often said that those people who have contributed the least to greenhouse gas emissions are the ones suffering the most from climate change, a more than accurate observation.

Understanding biosphere-precipitation relationships: Theory, model simulations and logical inferences

The four major biophysical controls of vegetation which govern land-atmosphere interaction emanate from the ability or vegetation to. (a) evapotranspire (b) trap solar radiation within leaf organizations. (c) regulate evapotranspiration by stomatal control and (d) modify (generally increase) the surface roughness on the scale of turbulent eddies, Simulation studies with General Circulation Models together with a few observational analyses have provided a rational understanding of vegetation-precipitation interaction. In studies with artificially enhanced vegetation-related processes a strong dependence of rainfall on vegetation has been inferred. For Sahelian and other tropical desert-border regions, where evapotranspiration is small, increasing the surface-albedo (desertification) decreases rainfall. When evaportranspiration and or land-surface roughness are increased in some selected regions - a potential effect of vegetation an increase in local rainfall is produced. The above effects both individually and jointly have simulated increased monsoon rainfall over the Indian subcontinent. Modelling studies directed at understanding the relationship between tropical forests and rainfall with realistic models of the biosphere have simulated a warmer and drier climate in response to Amazonian deforestation. Since forests absorb more solar energy and produce much larger evaportranspiration, as well as moisture convergence through the surface-roughness effect, positive feedback effect of forests on precipitation can be expected naturally. Our new simulation experiments not only reaffirmed the above results but also suggested potential global consequences due to the ongoing deforestation. From a synthesis of modeling results of the last decade, it if further inferred that variations in the biosphere-atmospheric interactions play an important role in redistributing continental precipitation to fulfill the survival and growth requirements of different biomes: forests, pasture, agricultural lands, and deserts.

Analysis of a Relaxation Process Caused by the Load Variation Adapted on the Basis of Second Order Electrical Model

The relaxation process of lithium batteries caused by load variation is considered. It is shown that such processes have strong dependence on internal physical and chemical processes and battery technical conditions. Theoretical expressions of the relaxation process caused by a step-like load variation have been obtained for 1st and 2nd order equivalent electrical circuits. The experimental investigations show that the obtained models fit the real relaxation processes and the behavior of the identified parameters could be explained by specific features of physical and chemical processes within the lithium battery. It should be noted that the obtained results can be generalized for a different type of electrochemical power source. The proposed approach makes it possible to provide means for electrochemical power source characterization and diagnostic, the main advantages of which are good time localization of measurement procedures and inexpensive apparatus implementation.

Impact of Ionic Liquid Structure and Loading on Gas Sorption and Permeation for ZIF-8-Based Composites and Mixed Matrix Membranes

Carbon dioxide (CO2) capture has become of great importance for industrial processes due to the adverse environmental effects of gas emissions. Mixed matrix membranes (MMMs) have been studied as an alternative to traditional technologies, especially due to their potential to overcome the practical limitations of conventional polymeric and inorganic membranes. In this work, the effect of using different ionic liquids (ILs) with the stable metal–organic framework (MOF) ZIF-8 was evaluated. Several IL@ZIF-8 composites and IL@ZIF-8 MMMs were prepared to improve the selective CO2 sorption and permeation over other gases such as methane (CH4) and nitrogen (N2). Different ILs and two distinct loadings were prepared to study not only the effect of IL concentration, but also the impact of the IL structure and affinity towards a specific gas mixture separation. Single gas sorption studies showed an improvement in CO2/CH4 and CO2/N2 selectivities, compared with the ones for the pristine ZIF-8, increasing with IL loading. In addition, the prepared IL@ZIF-8 MMMs showed improved CO2 selective behavior and mechanical strength with respect to ZIF-8 MMMs, with a strong dependence on the intrinsic IL CO2 selectivity. Therefore, the selection of high affinity ILs can lead to the improvement of CO2 selective separation for IL@ZIF-8 MMMs.