Ka-to-W Band EM Wave Propagation: Tropospheric Effects and Countermeasures

Near future satellite and terrestrial telecommunication (TLC) systems are expected to benefit from the use of operational frequencies spanning the Ka, Q, V and W bands, the main advantages being the availability of larger bandwidths and the smaller antenna size for a given gain. Moreover, the possibility of using on‐board antennas with enhanced directivity is attractive for satellite systems whose coverage area is subdivided into spot beams for frequency reallocation or regional services. For example, the W band is attractive for fixed satellite services (FSS), especially for geostationary high‐throughput systems (HTSs), in which the use of such frequencies for the feeder link (i.e. large available bandwidth) could reduce significantly the number of gateways with respect to Ka and Q/V bands. As for deep space missions, the main driver for the interest in using frequencies in the Ka to W bands is the possible increase in the on‐board antenna gain with respect to the values at X band considered for current or planned missions. The drawback of using electromagnetic waves at frequencies in Ka, Q, V and W bands is the definite impact of the impairments caused by the troposphere. As a consequence, the design of TLC systems at such frequencies, and in particular satellite‐based ones, cannot rely on the classical approach of simply assigning an extra power margin to counteract atmospheric fades. The extensive use of fade mitigation techniques (FMTs), such as link power control (LPC), site diversity or on‐board adaptive power allocation, from the propagation side, adaptive coding and modulation (ACM) and data rate adaptation (DRA), from the telecommunication side, is mandatory. A reduction of the quality of service (QoS) should also be considered. This chapter deals with all these aspects characterizing the propagation of electromagnetic waves in the Ka, Q, V and W bands, spanning from the main impairments induced by the troposphere (and how they change as the frequency increases), to how extreme atmospheric conditions can be handled making use of suitable FMTs

Numerical Modeling of Annular Laminar Film Condensation in Circular and Non-Circular Micro-Channels under Normal and Micro-Gravity

A theoretical and numerical model to predict film condensation heat transfer in mini, micro and ultra micro-channels of different internal shapes is presented in this thesis. The model is based on a finite volume formulation of the Navier-Stokes and energy equations and it includes the contributions of the unsteady terms, surface tension, axial shear stresses, gravitational forces and wall thermal conduction. Notably, interphase mass transfer and near-to-wall effects (disjoining pressure) are also included. This model has been validated versus various benchmark cases and versus published experimental results from three different laboratories, predicting micro-channel heat transfer data with an average error of 20 % or better. The conjugate heat transfer problem arising from the coupling between the thin film fluid dynamics, the heat transfer in the condensing fluid and the heat conduction in the channel wall has been studied and analyzed. The work has focused on the effects of three external wall boundary conditions: a uniform wall temperature, a non uniform wall heat flux and single-phase convective cooling. The thermal axial and peripheral conduction occurring in the wall of the channel can affect the behavior of the condensate film, not only because it redistributes the heat, but also because the annular laminar film condensation process is dependent on the local saturation to wall temperature difference. When moving from mini to micro and ultra-micro channels, the results shows that the axial conduction effects can become very important in the prediction of the wall temperature profile and they can not be ignored. Under these conditions, the overall performances of the heat exchanger become dependent not only on the fluid properties and the operative conditions but also on the geometry and wall material. Results obtained for steady state conditions are presented for circular, elliptical and flattened shape cross sections for R-134a and ammonia, for hydraulic diameters between 10 µm and 3 mm. Microscale condensation finds applications in heat pipes and compact heat exchangers for electronic equipment or spacecraft thermal control, in automotive condensers, in residential air conditioning and in refrigeration applications: the influence of the steady or unsteady gravitational field and of the inertia forces on the flow field and consequently on the heat transfer performances is investigated allowing the model to be applied as a design and optimization tool for enhanced heat exchangers

Current optical technologies for wireless access

The objective of this paper is to describe recent activities and investigations on free-space optics (FSO) or optical wireless and the excellent results achieved within SatNEx an EU-framework 6th programme and IC 0802 a COST action. In a first part, the FSO technology is briefly discussed. In a second part, we mention some performance evaluation criterions for the FSO. In third part, we briefly discuss some optical signal propagation experiments through the atmosphere by mentioning network architectures for FSO and then discuss the recent investigations in airborne and satellite application experiments for FSO. In part four, we mention some recent investigation results on modelling the FSO channel under fog conditions and atmospheric turbulence. Additionally, some recent major performance improvement results obtained by employing hybrid systems and using some specific modulation and coding schemes are presented

Correlation between nutritional status and hand grip strength in elderly

In the aging process, body changes occur, such as reduction of lean mass with impaired muscle strength, affecting the functional capacity. Currently, the Hand Grip Strength Test (HGST) is being used to evaluate the overall muscle strength as an aid in nutritional assessment. OBJECTIVE: To investigate the correlation between the HGST and nutritional status in the elderly. METHODS: Cross sectional study on elderly people attending outpatient of a Federal Public University. To evaluate the nutritional status, were used: body mass index (BMI), nutritional evaluation by Mini Nutritional Assessment (MNA), calf circumference and HGST performed with the aid of a hydraulic hand dynamometer. It was used as reference for the GSTP and the BMI, cutoff points divided by gender (SABE / OPAS Project). RESULTS: The sample was mostly formed (n = 42) by women (66.7%), with an average of 26.82 points in the MNA and BMI, most seniors were eutrophic - 46.4% women and 57.1% men. Men and women were averaged over 31 cm of calf circumference. The average strength for men was higher than women. There was no statistically significant difference between nutritional status classified by BMI and HGST for men and women, there was a statistically significant correlation (p 0.008) between the nutritional status classified by MNA and hand grip strength in the total sample. CONCLUSIONS: Among the methods to assess nutritional status, only MNA correlated positively with the HGST, which is a measure associated with the functionality in the elderly.No envelhecimento ocorrem mudanças corpóreas, dentre as quais a diminuição de massa magra com prejuízo na força muscular, afetando a capacidade funcional. Atualmente, o teste de Força de Preensão Palmar (FPP) está sendo utilizado para avaliar a força muscular global como auxiliar na avaliação nutricional. OBJETIVO: Verificar a correlação entre o estado nutricional e a FPP em idosos. MÉTODOS: Estudo transversal realizado com idosos atendidos em ambulatórios de uma universidade pública federal. Para a classificação do estado nutricional, utilizam-se: índice de massa corpórea (IMC), avaliação nutricional por meio da Mini-Avaliação Nutricional (MAN), circunferência da panturrilha (CP) e FPP realizada com auxílio de um dinamômetro manual hidráulico. Utilizaram-se como referência para a FPP e IMC os pontos de cortes divididos por gênero (projeto SABE/OPAS). RESULTADOS: Amostra constituída (n=42) na sua maioria por mulheres (66,7%), apresentando em média 26,82 pontos na MAN e pelo IMC a maioria dos idosos eram eutróficos - 46,4% mulheres e 57,1% homens. Homens e mulheres obtiveram média superior a 31 cm de circunferência da panturrilha (CP). A média de força para homens foi superior ao valor obtido pelas mulheres. Não houve diferença estatisticamente significante entre o estado nutricional classificado pelo IMC e a FPP para homens e mulheres; houve correlação estatisticamente significante (p 0,008) entre o estado nutricional classificado pela MAN e a força de preensão palmar na amostra total. CONCLUSÕES: Dentre os métodos para avaliar o estado nutricional, apenas a MAN correlacionou-se positivamente com a FPP, que é uma medida associada à funcionalidade em idosos.Universidade Federal de São Paulo (UNIFESP) Departamento de MedicinaUNIFESP, Depto. de MedicinaSciEL

Correlation between nutritional status and hand grip strength in elderly

In the aging process, body changes occur, such as reduction of lean mass with impaired muscle strength, affecting the functional capacity. Currently, the Hand Grip Strength Test (HGST) is being used to evaluate the overall muscle strength as an aid in nutritional assessment. OBJECTIVE: To investigate the correlation between the HGST and nutritional status in the elderly. METHODS: Cross sectional study on elderly people attending outpatient of a Federal Public University. To evaluate the nutritional status, were used: body mass index (BMI), nutritional evaluation by Mini Nutritional Assessment (MNA), calf circumference and HGST performed with the aid of a hydraulic hand dynamometer. It was used as reference for the GSTP and the BMI, cutoff points divided by gender (SABE / OPAS Project). RESULTS: The sample was mostly formed (n = 42) by women (66.7%), with an average of 26.82 points in the MNA and BMI, most seniors were eutrophic - 46.4% women and 57.1% men. Men and women were averaged over 31 cm of calf circumference. The average strength for men was higher than women. There was no statistically significant difference between nutritional status classified by BMI and HGST for men and women, there was a statistically significant correlation (p 0.008) between the nutritional status classified by MNA and hand grip strength in the total sample. CONCLUSIONS: Among the methods to assess nutritional status, only MNA correlated positively with the HGST, which is a measure associated with the functionality in the elderly.No envelhecimento ocorrem mudanças corpóreas, dentre as quais a diminuição de massa magra com prejuízo na força muscular, afetando a capacidade funcional. Atualmente, o teste de Força de Preensão Palmar (FPP) está sendo utilizado para avaliar a força muscular global como auxiliar na avaliação nutricional. OBJETIVO: Verificar a correlação entre o estado nutricional e a FPP em idosos. MÉTODOS: Estudo transversal realizado com idosos atendidos em ambulatórios de uma universidade pública federal. Para a classificação do estado nutricional, utilizam-se: índice de massa corpórea (IMC), avaliação nutricional por meio da Mini-Avaliação Nutricional (MAN), circunferência da panturrilha (CP) e FPP realizada com auxílio de um dinamômetro manual hidráulico. Utilizaram-se como referência para a FPP e IMC os pontos de cortes divididos por gênero (projeto SABE/OPAS). RESULTADOS: Amostra constituída (n=42) na sua maioria por mulheres (66,7%), apresentando em média 26,82 pontos na MAN e pelo IMC a maioria dos idosos eram eutróficos - 46,4% mulheres e 57,1% homens. Homens e mulheres obtiveram média superior a 31 cm de circunferência da panturrilha (CP). A média de força para homens foi superior ao valor obtido pelas mulheres. Não houve diferença estatisticamente significante entre o estado nutricional classificado pelo IMC e a FPP para homens e mulheres; houve correlação estatisticamente significante (p 0,008) entre o estado nutricional classificado pela MAN e a força de preensão palmar na amostra total. CONCLUSÕES: Dentre os métodos para avaliar o estado nutricional, apenas a MAN correlacionou-se positivamente com a FPP, que é uma medida associada à funcionalidade em idosos.Universidade Federal de São Paulo (UNIFESP) Departamento de MedicinaUNIFESP, Depto. de MedicinaSciEL

Una corniola con Vittoria incisa dalla Casa del Direttore Tronchetti di Nora

La campagna di scavo 2017, condotta a Nora dall’Università degli studi di Milano nell’area centrale, ha permesso il rinvenimento di una corniola di piccolissime dimensioni con incisa una Vittoria con corona e ramo di palma, secondo il tipo diffuso in età imperiale tra I e III d. C. Il rinvenimento di gemme sciolte in scavo urbano è sempre fatto notevole poiché della gemma ci è indicata la provenienza puntuale e una cronologia indicativa, a cui si aggiungono i confronti stilistici e iconografici con i pezzi musealizzati, già largamente oggetti di studio storico-artistico. Un confronto diretto ci è dato da un’altra corniola rinvenuta a Nora nel 2005, sempre nell’area centrale, recante anch’essa una Vittoria gradiente e datata alla seconda metà del II secolo d. C.The 2017 excavation campaign carried out in the central area of Nora by the University of Milan, allowed the discovery of a very small carnelian engraved with a crowned Victory holding a palm branch, similar to those commonly used in the Imperial age between I and III century AD. The discovery of loose gems in urban excavation is always a noteworthy event because the spot where the gem is found provides its punctual origin and an indicative chronology, moreover comparisons can be made with other museum pieces that have been already deeply studied under historical and artistic points of view. A direct comparison can be made with another Victory engraved on carnelian found in the central area of Nora in 2005, that is dated back to the second half of II century AD

Microfluidics on standard Petri dishes for bioscientists

Few microfluidic devices are used in biomedical labs, despite the obvious potential; reasons given include the devices are rarely made with cell-friendly materials, and liquids are inaccessibly buried behind solid confining walls. An open microfluidic approach is reviewed in which aqueous circuits with almost any imaginable 2D shape are fabricated in minutes on standard polystyrene Petri dishes by reshaping two liquids (cell-culture media plus an immiscible and bioinert fluorocarbon, FC40). Then, the aqueous phase becomes confined by fluid FC40 walls firmly pinned to the dish by interfacial forces. Such walls can be pierced at any point with pipets and liquids added or removed through them, while flows can be driven actively using external pumps or passively by exploiting local differences in Laplace pressure. As walls are robust, permeable to O2 plus CO2, and transparent, cells are grown in incubators and monitored microscopically as usual. It is hoped that this simple, accessible, and affordable fluid-shaping technology provides bioscientists with an easy entrée into microfluidics

Uncontrolled Diabetes as an Associated Factor with Dynapenia in Adults Aged 50 Years or Older: Sex Differences

BACKGROUND: Epidemiological studies demonstrate an association between diabetes and low neuromuscular strength (NMS). However, none have grouped participants into non-diabetics (ND), undiagnosed diabetics (UDD), controlled diabetics (CD) and uncontrolled diabetics (UCD) or investigated what glycated hemoglobin levels (HbA1c) are associated with low NMS (dynapenia) by sex. METHODS: We analyzed the association between UDD, CD and UCD and dynapenia, the extent to which the different groupings of these individuals modifies this association and the association between HbA1c levels and NMS, by sex, in a cross-sectional study involving 5,290 participants ≥ 50 years from the ELSA study. In the first two analyses, logistic regression models were used with dynapenia (grip strength < 26kg in men and < 16kg in women) as outcome and diabetes [ND, UDD, CD and UCD] as exposure. Next, linear regression was performed with grip strength as outcome and the participants classified based on HbA1c level as exposure. The models were adjusted by sociodemographic, behavioral and clinical characteristics. RESULTS: Compared to ND only UCD was associated with dynapenia (men OR=2.37 95% CI 1.36-4.14; women OR=1.67 95% CI 1.01-2.79). This association was less clear, particularly in women, when CD and UCD groups were merged. HbA1c ≥ 6.5% in men and ≥ 8.0% in women were associated with lower NMS. CONCLUSIONS: UCD increases the chance of dynapenia in both sexes. The different groupings based on diabetes status modify the association between UCD and dynapenia. The threshold of HbA1c associated with reduced NMS is lower in men compared to women

When Meta-Surfaces Meet Users: Optimization of Smart Radio Environments in 6G Sub-THz Communications

We consider a smart radio environment where meta-surfaces are employed to improve the performance of wireless networks working at sub-THz frequencies. To this end, we propose a comprehensive mathematical channel model, taking into account both the ability of the meta-surfaces to redirect the impinging signal towards a desired direction, and the signal reflection due to large objects. We show how the design of both the meta-surface and the transmitter precoder influences the network throughput. Furthermore, we compare several algorithms to optimize the effect of the meta-surfaces in a realistic scenario. As a result, a simpler algorithm that associates network users and meta-surfaces provides a performance comparable to more complex numerical optimization methods. Simulation results suggest how many users are supported in the designed system