Dielectric spectroscopy of a ferroelectric nematic liquid crystal and the effect of the sample thickness

The recently discovered ferroelectric nematic liquid crystals have been reported to exhibit very large dielectric permittivity values. Here, we report a systematic investigation of the dielectric behavior of a prototypical ferroelectric nematogen by varying the thickness of the parallel capacitor measuring cell. While in the non-polar high temperature nematic phase results show only slight differences due to slight variations of the alignment, the measured permittivity values in the ferroelectric nematic phase show a linear dependence on the cell thickness. It is also shown that the characteristic relaxation frequency decreases inversely proportionally to the thickness. The results are discussed in terms of three different available models based on different underlying mechanisms, accounting for cancellation of the probe electric fields by polarization reorientation or by ionic charges, or based on a recently proposed continuous phenomenological model

Evaluation of green walls as passive acoustic insulation system for buildings

Greenery on buildings is being consolidated as an interesting way to improve the quality of life in urban environments. Among the benefits that are associated with greenery systems for buildings, such as energy savings, biodiversity support, and storm-water control, there is also noise attenuation. Despite the fact that green walls are one of the most promising building greenery systems, few studies of their sound insulation potential have been conducted. In addition, there are different types of green walls; therefore, available data for this purpose are not only sparse but also scattered. To gather knowledge about the contribution of vertical greenery systems to noise reduction, especially a modular-based green wall, two different standardised laboratory tests were conducted. The main results were a weighted sound reduction index (Rw) of 15 dB and a weighted sound absorption coefficient (a) of 0.40. It could be concluded that green walls have significant potential as a sound insulation tool for buildings but that some design adjustments should be performed, such as improving the efficiency of sealing the joints between the modular pieces.The authors would like to thank the FEDER of the European Union for financial support via the project ‘‘G-GI3000/IDIX SILENTVEG: Barreras vegetales autónomas y sostenibles para la mitigación acústica y compensación del CO2 en vías de transporte, con seguimiento telemático’’ of the ‘‘Programa Operativo FEDER de Andalucía 2007-2013’’

Optimising Test Environment and Test Set Up for Characterizing Actual Thermal Performance of Building Components and Whole Buildings

The development of mathematical models that can reliably simulate the energy performance of a whole building or a building component with minimal discrepancy between the real and simulated data is a major aim of Building Physics science. In order to create models that accurately represent real physical phenomena it is necessity to perform tests on buildings and building components, producing real data that can be used to adjust and validate these models. If these tests are not undertaken correctly, incorrect data sets, insufficient data sets or excessively complex and expensive experiments may be performed. Thus, depending on the aim and the accuracy needed for the mathematical models, the test environment and test set up must be chosen correctly. This problem has been studied inside Subtask 2 of the Annex58 “Reliable building energy performance characterisation based on full scale dynamic measurements”. The aim was to come to a roadmap on how to measure the actual thermal performance of building components and whole buildings. This means under realistic boundary conditions (field exposure or artificial climate) and taking into account workmanship. Since there are many established methods and different Standards for different measurement purposes, the solution has been to organize the existing methods (both Standards and widely used non-Standard testing methods) into a decision tree. This decision tree begins with the question “What do you want to characterize?” and determines the context, environment, experimental design and analysis method being used by the user, terminating in a document reference. In a very simple format, following the decision tree and having a clear idea of what you need to characterize or model, you will reach an end branch of the decision tree where a testing Standard or testing method will be defined. The objective of this paper is to present the decision tree, its logic and the way it should be used

Cellular patterns and dry convection in textured dust storms at the edge of Mars North Polar Cap

We present a study of textured local dust storms that develop at the northern polar cap boundary on Mars springtime. We have used images obtained with VMC and HRSC cameras onboard Mars Express and MARCI on MRO to analyze dust storms captured from March to July 2019 (Ls = 350° in MY 34–Ls = 54° in MY 35). The textured storms grow in the longitude sector 150°E-210°E centered at latitude ~60°N and exhibit spiral, filamentary and compact shapes that change and evolve rapidly in a daily basis. The storms translate by prevailing east and southeast winds with speeds 15–45 ms−1. In some areas of their interiors they show organized clusters of cells formed typically by 100 elements with sizes ~5–30 km with a length/width ratio ~ 1.2–3 in the wind direction. The cells have elongated downwind tails with lengths 4–8 times the cell size. The cells top altitudes are ~6–11 km above their surroundings. We propose that the spirals grow as baroclinic vortices within a vertically sheared eastward jet present at this epoch in Mars due to the intense meridional temperature gradient at the polar cap edge. We show using a simple one-dimensional model that the cells can be produced by shallow dry convection with dust acting as the heating source to generate the updrafts. These patterns resemble those seen in laboratory experiments and on clouds in Earth's atmosphere and can serve to comparatively elucidate and discern the different mechanisms at work in each case

Analyzing factors that influence the folk use and phytonomy of 18 medicinal plants in Navarra

BACKGROUND: This article analyzes whether the distribution or area of use of 18 medicinal plants is influenced by ecological and cultural factors which might account for their traditional use and/or phytonymy in Navarra. This discussion may be helpful for comparative studies, touching as it does on other ethnopharmacological issues: a) which cultural and ecological factors affect the selection of medicinal plants; b) substitutions of medicinal plants in popular medicine; c) the relation between local nomenclature and uses. To analyze these questions, this paper presents an example of a species used for digestive disorders (tea and camomile: Jasonia glutinosa, J. tuberosa, Sideritis hyssopifolia, Bidens aurea, Chamaemelum nobile, Santolina chamaecyparissus...), high blood pressure (Rhamnus alaternus, Olea europaea...) or skin diseases (Hylotelephium maximum, H. telephium, Anagallis arvensis, A. foemina). METHODS: Fieldwork began on January 2004 and continued until December 2006. During that time we interviewed 505 informants in 218 locations in Navarra. Information was collected using semi-structured ethnobotanical interviews, and we subsequently made maps using Arc-View 8.0 program to determine the area of use of each taxon. Each map was then compared with the bioclimatic and linguistic map of Navarra, using the soil and ethnographic data for the region, and with other ethnobotanical and ethnopharmacological studies carried out in Europe. RESULTS: The results clearly show that ecological and cultural factors influence the selection of medicinal plants in this region. Climate and substrate are the most important ecological factors that influence the distribution and abundance of plants, which are the biological factors that affect medicinal plant selection. CONCLUSION: The study of edaphological and climatological factors, on the one hand, and culture, on the other, can help us to understand why a plant is replaced by another one for the same purposes, either in the same or in a different area. In many cases, the cultural factor means that the use of a species is more widespread than its ecological distribution. This may also explain the presence of synonyms and polysemies which are useful for discussing ethnopharmacological data

Sustentabilidad y tecnología. Herramientas para la gestión segura y eficiente del hábitat

Por décadas permeó una visión de la tecnología como una de las principales fuentes del ataque al medio ambiente y de su degradación. Hoy se le considera como un aliado para combatir los efectos negativos de la perenne negligencia ecológica humana. El uso de la tecnología para la implementación de estrategias innovadoras y eficaces en favor del medio ambiente, un hábitat seguro y sustentable, se abordó en el Congreso Internacional sobre Sustentabilidad en los Hábitats, realizado en 2016. De este encuentro entre estudiantes, especialistas, autoridades y organizaciones civiles de América Latina, Asia y Europa emana este libro, que incluye dos ejes de relevancia global: los retos en el manejo sustentable de los recursos naturales y el uso de tecnologías para la edificación sustentable. En el primero se atienden desde los riesgos asociados al crecimiento demográfico desproporcionado hasta acciones de carácter remedial para la contaminación; mientras que en el segundo se aborda el desarrollo de tecnología e infraestructura para mejorar el hábitat urbano, así como procesos donde alumnos y profesores confeccionan soluciones para la sustentabilidad energética. En su conjunto, es una obra de consulta que busca ser un detonador para generar nuevas líneas de trabajo, repensar las soluciones y dialogar con lectores interesados en la construcción de un mundo mejor.Consejo Estatal de Ciencia y Tecnología de Jalisc

Outbreak of H3N2 influenza at a US military base in Djibouti during the H1N1 pandemic of 2009.

PMC3855413BACKGROUND: Influenza pandemics have significant operational impact on deployed military personnel working in areas throughout the world. The US Department of Defense global influenza-like illness (ILI) surveillance network serves an important role in establishing baseline trends and can be leveraged to respond to outbreaks of respiratory illness. OBJECTIVE: We identified and characterized an operationally unique outbreak of H3N2 influenza at Camp Lemonnier, Djibouti occurring simultaneously with the H1N1 pandemic of 2009 [A(H1N1)pdm09]. METHODS: Enhanced surveillance for ILI was conducted at Camp Lemonnier in response to local reports of a possible outbreak during the A(H1N1)pdm09 pandemic. Samples were collected from consenting patients presenting with ILI (utilizing a modified case definition) and who completed a case report form. Samples were cultured and analyzed using standard real-time reverse transcriptase PCR (rt-RT-PCR) methodology and sequenced genetic material was phylogenetically compared to other published strains. RESULTS: rt-RT-PCR and DNA sequencing revealed that 25 (78%) of the 32 clinical samples collected were seasonal H3N2 and only 2 (6%) were A(H1N1)pdm09 influenza. The highest incidence of H3N2 occurred during the month of May and 80% of these were active duty military personnel. Phylogenetic analysis revealed that sequenced H3N2 strains were genetically similar to 2009 strains from the United States of America, Australia, and South east Asia. CONCLUSIONS: This outbreak highlights challenges in the investigation of influenza among deployed military populations and corroborates the public health importance of maintaining surveillance systems for ILI that can be enhanced locally when needed.JH Libraries Open Access Fun

EBC Annex 58 Reliable Building Energy Performance Characterisation based on full scale dynamic measurements

This report summarizes the activities that were carried out in the framework of Subtask 2 of IEA Annex 58. Subtask 2 dealt with the challenge of optimizing full scale dynamic testing. The aim was to arrive at a roadmap presenting the user with reliable methods used to measure the actual thermal performance of building components and whole buildings. The roadmap (using a decision tree logic) is aimed at multiple audiences from both academic and industry backgrounds. The present report focuses on the development of the Decision Tree and how it changed throughout the course of Annex 58, giving an overview of the presented work

Feasibility of small-scale gas engine-based residential cogeneration in Spain

Nowadays all countries are developing their own policies to promote cogeneration in the small-scale residential sector. In this paper the feasibility of small-scale gas engine-based residential cogeneration plants under the current Spanish regulation is studied. A unitary thermal load profile is obtained to characterised the thermal demand of residential applications in Spain. This unitary profile is used to analyse the potential of cogeneration in the small-scale range of powers (100-1000 kW). A complete characterisation of the gas fuelled engines in the market is performed and subsequently used to evaluate the economic feasibility within the selected range by means of a self-tailored simulation model. It is underlined how the thermal storage is a crucial element that should be suitably included in a residential cogeneration plant and the distortions that the actual pricing system adds to the profitability of residential plants of different sizes. Finally a sensibility study is carried out in order to evaluate how the Spanish regulation is able to deal with future variations in the energy prices. It is shown that a rise in the price of the natural gas increases the current feasibility of a plant while a decrease descends the profitability.Cogeneration Spanish regulation Feasibility study