Stock mechanics: a general theory and method of energy conservation with applications on DJIA

A new method, based on the original theory of conservation of sum of kinetic and potential energy defined for prices is proposed and applied on Dow Jones Industrials Average (DJIA). The general trends averaged over months or years gave a roughly conserved total energy, with three different potential energies, i.e. positive definite quadratic, negative definite quadratic and linear potential energy for exponential rises (and falls), sinusoidal oscillations and parabolic trajectories, respectively. Corresponding expressions for force (impact) are also given. Keywords:Comment: 14 pages, 3 figures, scehudled for IJMPC 17/ issue

Lightweight Carbon Fiber Mirrors for Solar Concentrator Applications

Lightweight parabolic mirrors for solar concentrators have been fabricated using carbon fiber reinforced polymer (CFRP) and a nanometer scale optical surface smoothing technique. The smoothing technique improved the surface roughness of the CFRP surface from ~3 {\mu}m root mean square (RMS) for as-cast to ~5 nm RMS after smoothing. The surfaces were then coated with metal, which retained the sub-wavelength surface roughness, to produce a high-quality specular reflector. The mirrors were tested in an 11x geometrical concentrator configuration and achieved an optical efficiency of 78% under an AM0 solar simulator. With further development, lightweight CFRP mirrors will enable dramatic improvements in the specific power, power per unit mass, achievable for concentrated photovoltaics in space.Comment: IEEE Photovoltaic Specialist Conference (PVSC), DC, USA, 201

Extremely broadband ultralight thermally emissive metasurfaces

We report the design, fabrication and characterization of ultralight highly emissive metaphotonic structures with record-low mass/area that emit thermal radiation efficiently over a broad spectral (2 to 35 microns) and angular (0-60 degrees) range. The structures comprise one to three pairs of alternating nanometer-scale metallic and dielectric layers, and have measured effective 300 K hemispherical emissivities of 0.7 to 0.9. To our knowledge, these structures, which are all subwavelength in thickness are the lightest reported metasurfaces with comparable infrared emissivity. The superior optical properties, together with their mechanical flexibility, low outgassing, and low areal mass, suggest that these metasurfaces are candidates for thermal management in applications demanding of ultralight flexible structures, including aerospace applications, ultralight photovoltaics, lightweight flexible electronics, and textiles for thermal insulation

Effect of irrigation on sap flux density variability and water use estimate in cherry (Prunus avium) for timber production: Azimuthal profile, radial profile and sapwood estimation

9 páginas.-- 7 figuras.-- 3 tablas.-- 30 referenciasInformation on tree water use in plantations for high quality wood is scarce, thus studies are needed toproperly estimate the irrigation demand of these plantations. Plant water use estimation with sap flowsensors has been used extensively. However, biases in tree sap flow estimate can arise from variationson radial and azimuthal profiles of sap flux density and also from the sapwood area considered for theup-scaling from sap flux density to sap flux. This work aimed to (1) study the spatial variations of sapflux density in cherry trees in a timber orientated plantation, (2) compare several methods to estimatesapwood depth in cherry trees and (3) to evaluate the effect of drip irrigation on these factors. The resultsshowed that most of the studied trees had decreasing radial sap flux density profiles with depth asexpected. However, the three irrigated trees of bigger sizes still showed high sap flux densities in theirinner tissues, at contrast with the rest of the trees and especially with the non irrigated ones of similarsize with values close to 20% of the sap flux density measured at 1 cm depth from cambium. On the otherhand, the different methods tested to estimate sapwood depth gave significantly different results andonly the two methods of visual identification in wood cores based on color change and measurementsof sap flux densities along the xylem radius may be considered suitable for scaling purposes. Moreover,azimuthal variation pattern was found to be random in all the studied trees, and the ranking between theaspects (north, south, east and west) was not affected by either drip irrigation or sun exposition, and thusmeasuring sap flux density in any particular aspect has been shown to be suitable to estimate the overalltree sap flux. We conclude that more studies are necessary to properly assess the radial profile of sapflux density, especially when considering the high sap flux density in the inner tissues of the three biggerirrigated trees as compared to the other trees, and also how this pattern seemed to indicate sapwooddepths values very contrasted to the ones estimated from color change in wood cores.Acknowledgments MONTES (CSD 2008-00040) projectsfunded by the Spanish Ministry of Science and Innovation. The firstauthor was the recipient of a FPI grant from the Spanish Ministryof Economy and Competitiveness. The field work of Eulalia Serra,Beatriz Grau, Marc Ferrer and Cristian Morales is highly appreci-ated.Peer reviewe

Enhancing infrastructure resilience in wildfire management to face extreme events: Insights from the Iberian Peninsula

Factors such as human activity and climate change are contributing to an increase in the frequency and intensity of wildfires. This problem has challenged society’s knowledge, response capacity, and resilience, revealing its inadequacy to cope with the new wildfire regime characterized by extreme wildfire events (EWE). Policies on wildfire management mainly focus on suppression and managing emergencies, which may be insufficient to reduce EWE’s incidence and cope with its impact. Consequently, there is a lack of tools to support decision-making in wildfire management in other important aspects, such as prevention and protection. This study examines global wildfire policies specifically in the Iberian Peninsula (Portugal and Spain), including cross-border policies. A GIS-based tool to evaluate different normal and extreme wildfire management policies is applied to a cross-border case study, paying attention to the impact on critical land-based transport systems. A relevant outcome of the tool application is that suppression must be complemented with other wildfire management strategies in the analyzed area. The gained insights can help stakeholders to improve decision-making in wildfire management to successfully address EWE.This work was partly financed by FCT/ MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/ 04029/2020 (doi.org/10.54499/UIDB/04029/2020), and under the Associate Laboratory Advanced Production and Intelligent Systems ARISE under reference LA/P/0112/2020

Policies towards the resilience of road-based transport networks to wildfire events: the Iberian case

Wildfires are becoming more intense and frequent. This problem has tested the knowledge, response capacity, and resilience achieved by society throughout history, making it clear that they are insufficient to face this new wildfire regime. The effectiveness of the related policies mainly focused on fire suppression rather than prevention is increasingly insufficient and questionable. Consequently, there is a clear lack of tools to assess the impact of wildfire preventive actions. Therefore, it is imperative to review wildfire management practices, policies, and the tools used to support decision-making in this regard. This study performs an analysis of wildfire policies applied in the Iberian Peninsula case (Portugal and Spain), including cross-border policies and the role of road transport networks. A novel simplified methodology is included to evaluate different normal and extreme forest fire management policies in road transport infrastructures. The methodology includes different parameters related to wildfires, such as sources of exposure, identification of natural and artificial barriers, and traffic conditions that capture the economic characteristics of the studied area. The information provided by the tool is useful for strategic investment planning, resource prioritization, and evacuation time management. In addition, due to its simplicity of application, it is a useful tool for cross-border areas.This work was partly financed by FCT / MCTES through national funds (PIDDAC) under the R\&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB / 04029/2020, and under the Associate Laboratory Advanced Production and Intelligent Systems ARISE under reference LA/P/0112/2020. This work is financed by national funds through FCT, Foundation for Science and Technology, under grant agreement 2020.05755.BD attributed to the first author

Flavonoids Of Lonchocarpus Montanus A.m.g. Azevedo And Biological Activity.

The analysis of root extracts from Lonchocarpus montanus A.M.G. Azevedo resulted in the isolation of twenty three compounds chiefly flavonoids of which five (four flavonoids and one benzophenone) are described for the first time. The molecular structures of the new compounds (1-5) were determined through spectral analysis (UV, IR, MS and NMR) as being: 2'-hydroxy-8-(alpha,alpha-dimethylallyl)-2, 2-dimethylpyrano-(5,6:3',4')-dibenzoylmethane (1), 2'-methoxy-8-(alpha,alpha-dimethylallyl)-2, 2-dimethylpyrano-(5,6:3',4')-dibenzoylmethane (2), 4'-methoxy-2,2-dimethylpyrano-(5,6:8,7)-flavone (3), 2-(1-hydroxy-1-methylethyl)-furano-(4,5:8,7)-flavone (4) and [2'-methoxy-furano-(4,5:3',4')-phenyl]-phenylmethanone (5). Additionally, fifteen fatty acids were detected through GC-MS analysis of the corresponding methyl esters [(CH3)2CH(CH2)8COOH and CH3(CH2)nCOOH (n = 6, 12-24)]. Quantitative RP-HPLC showed that the most abundant flavonoids in the petroleum ether and dichloromethane extracts were pongamol (19%) and lanceolatine B (8.0%), respectively. In the bioautography assay, the extracts, pongamol (9), lanceolatine B (10), isolonchocarpin (14), derriobtusone A (17) and medicarpine (18) were active against Staphylococcus aureus whereas 9 also against Bacillus subtilis and Cladosporium cladosporioides. Compound 1, 2,2-dimethylpyrano-(5,6:8,7)-flavone (11) and furano-(1200,1300:7,8)- 4'-methoxy flavone (12) were active against Fusarium oxysporium whereas 11 also against Rhizopus orizae. The extracts, compounds 9, 10, 17 and (E)-7-O-methoxypongamol (23) displayed high toxicity in the brine shrimp lethality assay.79351-6