191 research outputs found
Energy Expenditure at Rest and during Walking in Patients with Chronic Respiratory Failure: A Prospective Two-Phase Case-Control Study
Measurement of Energy Expenditure (EE) at rest (REE) and during physical activities are increasing in interest in chronic patients. In this study we aimed at evaluating the validity/reliability of the SenseWear\uaeArmband (SWA) device in terms of REE and EE during assisted walking in Chronic Respiratory Failure (CRF) patients receiving long-term oxygen therapy (LTOT).In a two-phase prospective protocol we studied 40 severe patients and 35 age-matched healthy controls. In phase-1 we determined the validity and repeatability of REE measured by SWA (REEa) in comparison with standard calorimetry (REEc). In phase-2 we then assessed EE and Metabolic Equivalents-METs by SWA during the 6-minute walking test while breathing oxygen in both assisted (Aid) or unassisted (No-Aid) modalities. When compared with REEc, REEa was slightly lower in patients (1351\ub1169 vs 1413\ub1194 kcal/day respectively, p<0.05), and less repeatable ithan in healthy controls (0.14 and 0.43 coefficient respectively). COPD patients with CRF patients reported a significant gain with Aid as compared with No-Aid modality in terms of meters walked, perceived symptoms and EE.SWA provides a feasible and valid method to assess the energy expenditure in CRF patients on LTOT, and it shows that aided walking results in a substantial energy saving in this population
Influence of the brood rearing temperature on honey bee development and susceptibility to intoxication by pesticides
contribution to session IV
Test methodolog
Non-hermiticity in spintronics: oscillation death in coupled spintronic nano-oscillators through emerging exceptional points
The emergence of exceptional points (EPs) in the parameter space of a
non-hermitian (2D) eigenvalue problem is studied in a general sense in
mathematical physics, and has in the last decade successively reached the scope
of experiments. In coupled systems, it gives rise to unique physical phenomena,
which enable novel approaches for the development of seminal types of highly
sensitive sensors. Here, we demonstrate at room temperature the emergence of
EPs in coupled spintronic nanoscale oscillators and hence exploit the system's
non-hermiticity. We describe the observation of amplitude death of
self-oscillations and other complex dynamics, and develop a linearized
non-hermitian model of the coupled spintronic system, which properly describes
the main experimental features. Interestingly, these spintronic nanoscale
oscillators are deployment-ready in different applicational technologies, such
as field, current or rotation sensors, radiofrequeny and wireless devices and,
more recently, novel neuromorphic hardware solutions. Their unique and
versatile properties, notably their large nonlinear behavior, open up
unprecedented perspectives in experiments as well as in theory on the physics
of exceptional points. Furthermore, the exploitation of EPs in spintronics
devises a new paradigm for ultrasensitive nanoscale sensors and the
implementation of complex dynamics in the framework of non-conventional
computing
BeeNet and BEST: the Italian 'beekeeping and environment' projects
Tese de doutoramento em Engenharia Civil, no ramo de Geotecnia, apresentada ao Departamento de Engenharia Civil da Faculdade de CiĆŖncias e Tecnologia da Universidade de CoimbraO estudo e a caracterizacĢ§aĢo de solos incoerentes, nomeadamente areias saturadas, foram impulsionados pela ocorreĢncia de diversos incidentes, entre os quais se destacam os sismos de 1964 no Alasca (Estados Unidos da AmeĢrica) e em Niigata (JapaĢo). Os severos danos registados durante estes sismos alertaram a comunidade cientiĢfica para os efeitos associados aos fenoĢmenos de liquefacĢ§aĢo, impulsionando o desenvolvimento da disciplina de engenharia siĢsmica geoteĢcnica. No final do seĢculo XX, o iniĢcio do estudo sistemaĢtico do comportamento de solos no domiĢnio das pequenas deformacĢ§oĢes vem complementar o conhecimento da resposta naĢo drenada de areias, fornecendo ferramentas adequadas para o dimensionamento tanto aos estados limites de utilizacĢ§aĢo como aos estados limites uĢltimos.
Apesar dos avancĢ§os cientiĢficos no estudo do comportamento de areias saturadas, abalos siĢsmicos mais recentes, como os sismos de Kobe (1995, JapaĢo) e Kocaeli (1999, Turquia), demonstraram que a previsaĢo de fenoĢmenos de liquefacĢ§aĢo e seus efeitos naĢo estaĢo totalmente compreendidos. Atendendo aĢ histoĢria siĢsmica de Portugal bem como ao facto de as principais cidades portuguesas se situarem no litoral ou nas margens de rios, o Departamento de Engenharia Civil da Universidade de Coimbra, com a colaboracĢ§aĢo de outras duas instituicĢ§oĢes de ensino superior nacionais, encetou, em 2008, um vasto programa de investigacĢ§aĢo sobre ferramentas para o dimensionamento baseado no desempenho em macicĢ§os suscetiĢveis aĢ liquefacĢ§aĢo. Para esta investigacĢ§aĢo, foi escolhida uma areia local recolhida nas margens do Rio Mondego que, apoĢs o seu tratamento, origina uma fracĢ§aĢo uniforme designada de areia de Coimbra, material que se propoĢe caracterizar, dando seguimento a vaĢrios estudos jaĢ elaborados.
Os dados da extensa investigacĢ§aĢo laboratorial concretizada resultam de ensaios realizados sobre amostras ciliĢndricas de seccĢ§aĢo cheia mas, essencialmente, de ensaios executados num HCA Mark II sobre provetes ciliĢndricos ocos cujas dimensoĢes saĢo 60Di:100Do:200H (mm). A conclusaĢo da instalacĢ§aĢo deste equipamento, o desenvolvimento de procedimentos de calibracĢ§aĢo dos seus instrumentos de medicĢ§aĢo bem como o estabelecimento de teĢcnicas de preparacĢ§aĢo de provetes e de execucĢ§aĢo de ensaios constituem a primeira parte desta dissertacĢ§aĢo. Estas informacĢ§oĢes teĢcnicas, que incluem a descricĢ§aĢo detalhada de todos os componentes do HCA da Universidade de Coimbra, eĢ complementada com uma exposicĢ§aĢo dos pressupostos e conceitos teoĢricos que permitem a definicĢ§aĢo dos estados de tensaĢo e deformacĢ§aĢo em amostras ciliĢndricas ocas.
A caracterizacĢ§aĢo avancĢ§ada do comportamento mecaĢnico da areia de Coimbra, que sucede estudos microscoĢpicos e de identificacĢ§aĢo que complementam informacĢ§oĢes anteriormente publicadas, perfaz a segunda parte desta dissertacĢ§aĢo. Os ensaios laboratoriais incidem sobre amostras de areia reconstituiĢdas e saturadas, incluindo ensaios monotoĢnicos e ciĢclicos em condicĢ§oĢes naĢo drenadas para diferentes modos de carregamento e estados iniciais. A versatilidade do HCA, aleĢm da caracterizacĢ§aĢo no domiĢnio das pequenas deformacĢ§oĢes do solo analisado, permite a imposicĢ§aĢo de condicĢ§oĢes de restricĢ§aĢo de deformacĢ§aĢo pouco convencionais no estudo de liquefacĢ§aĢo de areias. Por fim, descreve-se o comportamento poĢs-liquefacĢ§aĢo da areia de Coimbra, com especial enfoque nas deformacĢ§oĢes volumeĢtricas e na variacĢ§aĢo do estado de tensaĢo.The characterisation of cohesionless soils, namely saturated sands, was encouraged by several seismic events such as the 1964 earthquakes in Alaska (USA) and Niigata (Japan). The severe damages observed during and after these earthquakes drew the attention of the scientific community to liquefaction-related phenomena. It is also accepted that these two earthquakes are at the origin of the geotechnical earthquake engineering. By the end of the 20th century, extensive research programmes on the small strain behaviour of soils improved considerably the knowledge of the stress- strain response of sands, providing the appropriate tools for the design of both serviceability and ultimate limit states.
Despite all the scientific advances in the study of the behaviour of saturated sand, recent earthquakes, such as Kobeās earthquake in 1995 (Japan) and the Kocaeliās earthquake in 1999 (Turkey), sowed that the prediction of liquefaction-related phenomena and their effects were not fully understood. Given Portugalās seismic history, as well as the fact that its major cities are located on the coast or in proximity to rivers, the Department of Civil Engineering of the University of Coimbra, Portugal, began in 2008, in collaboration with two other Portuguese Universities, a comprehensive research programme with the objective of developing performance- based design tools for liquefiable deposits. A local sand, named Coimbra sand, obtained from sand collected on the banks of the Mondego River, has been used for this investigation. The present investigation aims at characterising the mechanical response of this sand, highlighting some features of its behaviour that have not been studied yet.
The comprehensive experimental research carried out comprises data from tests performed on both conventional cylindrical samples and hollow cylindrical samples with dimensions 60Di:100Do:200H (mm) tested in a Hollow Cylinder Apparatus Mark II. The set up of this apparatus, the development of the calibration procedures for the measurement instruments, as well as the proposal of sample preparation techniques, compose the first part of this thesis. This technical information, which comprises a fully detailed description of all of the University of Coimbraās HCA components, is accompanied by a discussion of all the assumptions and theoretical principles needed for the definition of the stress and strain states in a hollow cylindrical sample. Microscopic and fundamentals studies, which complete the data published in previous works, precede the advanced characterisation of the mechanical behaviour of Coimbra sand, constituting the second part of this thesis. All the laboratory tests are carried on remoulded and saturated sand samples, and comprise monotonic and cyclic undrained shear tests for both different loading modes and initial states. The versatility of the HCA enables not only the characterization of the small strain stiffness behaviour of Coimbra sand but also the use of unconventional deformation-restricted conditions in the study of sand liquefaction. Lastly, the post-liquefaction behaviour of Coimbra sand is described, with particular emphasis on the development of volumetric strains and evolution of stress state.LāeĢtude et la caracteĢrisation des sols incoheĢrents, notamment des sables satureĢs, ont eĢteĢ encoutageĢes par de tragiques eĢveĢnements sismiques, parmi lesquels se trouvent les tremblements de terre de 1964 en Alaska (Etats-Unis dāAmeĢrique) et aĢ Niigata (Japon). Les importants deĢgaĢts enregistreĢs au cours de ces violents tremblements de terre ont alerteĢ la communauteĢ scientifique et face aux effets de ces pheĢnomeĢnes lieĢs aĢ la liqueĢfaction des sables, une discipline du domaine du GeĢnie Civil a eĢteĢ creĢeĢe: Parasismique et GeĢotechnique. Vers la fin du XXe sieĢcle, le deĢbut des eĢtudes du comportement des sols sous lāhypotheĢse des petites perturbations vient compleĢter la connaissance du comportement non draineĢ des sables et fournir les outils neĢcessaires pour le dimensionnement aux eĢtats limites ultimes et en service.
MalgreĢ tous les progreĢs scientifiques, des tremblements de terre reĢcents, comme ceux que ont eut lieu aĢ Kobe en 1995 (Japon) et aĢ Kocaeli en 1999 (Turquie), ont deĢmontreĢ que la preĢdiction bien comme les effets des pheĢnomeĢnes lieĢs aĢ la liqueĢfaction nāeĢtaient pas inteĢgralement assimileĢs. EĢtant donneĢ lāhistoire sismologique du Portugal aussi bien comme le fait que les villes portugaises les plus importantes sont eĢtablies sur la coĢte ou sur les berges de fleuves, le DeĢpartement de GeĢnie Civil de lāUniversiteĢ de Coimbra au Portugal, en collaboration avec deux autres eĢtablissements de geĢnie civil nationaux, a entameĢ, en 2008, un ample programme de recherche sur les outils pour le dimensionnement baseĢ sur la performance des sols susceptibles aĢ la liqueĢfaction. Les recherches sont meneĢes sur le sable de Coimbra, qui est le reĢsultat du traitement dāun sable locale recueilli sur les rives du fleuve Mondego. La preĢsente eĢtude vise caracteĢriser ce sol en apportant des renseignements encore jamais eĢtudieĢs auparavant.
Les reĢsultats de cette ample recherche reĢaliseĢe en laboratoire proviennent dāessais triaxiaux sur des eĢchantillons conventionnels de sable et sur des eĢchantillons cylindriques creux. Ces derniers ont eĢteĢ effectueĢs avec une cellule triaxiale aĢ cylindre creux du type HCA Mark II, qui permet, entre autres, dāessayer des eĢprouvettes cylindriques creuses dont les dimensions sont de 60Di:100De:200H (mm). LāacheĢvement de lāinstallation de cet eĢquipement, le deĢveloppement de proceĢdures dāeĢtalonnage de ses instruments de mesure bien comme de techniques de preĢparation dāeĢprouvettes creuses composent la premieĢre partie de cette theĢse. Cet exposeĢ inclut une description treĢs deĢtailleĢe du HCA de lāUniversiteĢ de Coimbra ainsi que lāexposition des hypotheĢses et des notions theĢoriques qui permettent de deĢfinir les eĢtats de contrainte et de deĢformation dans des essaies de cylindres creux.
La deuxieĢme partie de cette theĢse rassemble les reĢsultats de la caracteĢrisation du comportement meĢcanique du sable de Coimbra, qui succeĢde aĢ des eĢtudes microscopiques et dāidentification. Les eĢtudes en laboratoire comprennent uniquement des eĢchantillons de sable remanieĢs et satureĢs, lesquels sont soumis aĢ des essais de cisaillement non draineĢs sous diffeĢrents modes de chargements monotones et cycliques pour diffeĢrentes conditions initiales. La polyvalence de la cellule triaxiale aĢ cylindre creux permet aussi dāimposer des restrictions de deĢformations non conventionnelles dans lāeĢtude de la liqueĢfaction des sables e ains que leur caracteĢrisation sous lāhypotheĢse des petites perturbations. En dernier lieu, ce travail preĢsente des donneĢes sur le comportement post liqueĢfaction du sable de Coimbra, en mettant lāaccent sur les deĢformations volumeĢtriques et la variation de lāeĢtat de contrainte
Project of a multibeam UHF receiver to improve survey capabilities
The Institute of Radioastronomy (IRA-Bologna) of the National Institute for Astrophysics of Italy (INAF ā Rome) joined the European group for the Square Kilometer Array Design Study (SKA-DS) in the frame of the FP6 program. One of the goals of the Design Study was the construction and test of a state of the art very small SKA prototype. A segment (1/8) of the N/S arm of the large Northern Cross array (408 MHz+/ā8 MHz) was exploited to obtain a prototype array, made up by 8 cylindrical concentrators (23.5 mtĆ7.5 mt) equipped with 4 receivers each. In this way a 32 receivers array with a total collecting area of about 1400 m2 was obtained. Signals are directly carried from the receivers, located on the focal lines, down to the back end, located in the processing room, via a very cost effective analog optical links. Here a fast back end, presently based on Field Programmable Gate Array (FPGA) Berkeley-Roach boards, takes care of running the required complex algorithms to perform (non-adaptive) multi-beamforming with a 2D FFT. The main advantage of such an already working array is to produce 21 independent 31āĆ104ā beams located inside a 38 deg2 Field Of View (FoV). Our plan is to search for funds to refit the remaining 56 cylinders of the N/S arm, to dramatically increase both the sensitivity and number of beams (pixels) placed in the same FoV. In this way, it could be possible to perform a deep SETI survey in the UHF band by an about 11.200 m2 antenna (equivalent to a 119 m dish), a 37.6 deg2 FOV and 189 independent beams. The system could be further expanded by installing more receivers on each N/S focal line, increasing the FOV and the number of pixels with the same sensitivity. Assuming that adequate funds could be found for refitting the giant E/W arm as well, an equivalent 180 m dish could be obtained to perform a very deep SETI sky survey with a 120 deg2 FOV at high sensitivity. This would allow a very fast and deep sky survey in the UHF band
Spring honey bee losses in Italy
Honey bee poisoning incidents and monitoring schemes Background: During last years several cases of bee losses have been reported during the period of corn sowing in different European countries. In Italy an institutional system for bee losses survey does not exist and therefore some Italian regions decided to organise an official network to collect data and analyse dead bee samples. Results: Collected data indicate that the higher number of bee losses events occurred in intensively cultivated flat areas, located in the North of Italy, mainly during or after corn sowing. The chemical analyses of dead bees revealed the presence of three neonicotinoid residues: imidacloprid was found in 25.7% of the sample, thiamethoxam in 2.8%, clothianidin in 25.7%, both imidacloprid and thiamethoxam in 4.7%. The visual examination and the virological analyses excluded pathological causes. Conclusion: The spatial and temporal correlation between hive damages and corn sowing and the presence of residues of active ingredients used for seed dressing (imidacloprid, thiamethoxam and clothianidin) in almost half of the samples confirms the connection between spring mortality and the sowing of corn seed dressed with neonicotinoids. Keywords: honeybee mortality, neonicotinoids, seed dressing, corn sowing, dust dispersion.Ā Ā Ā Ā Ā Ā
The Northern Cross Fast Radio Burst project -- III. The FRB-magnetar connection in a sample of nearby galaxies
Fast radio bursts (FRBs) are millisecond radio transients observed at
cosmological distances. The nature of their progenitors is still a matter of
debate, although magnetars are invoked by most models. The proposed
FRB-magnetar connection was strengthened by the discovery of an FRB-like event
from the Galactic magnetar SGR J1935+2154. In this work, we aim to investigate
how prevalent magnetars such as SGR J1935+2154 are within FRB progenitors. We
carried out an FRB search in a sample of seven nearby (< 12 Mpc) galaxies with
the Northern Cross radio telescope for a total of 692 h. We detected one 1.8 ms
burst in the direction of M101 with a fluence of Jy ms. Its
dispersion measure of 303 pc cm places it most-likely beyond M101.
Considering that no significant detection comes indisputably from the selected
galaxies, we place a 38 yr upper limit on the total burst rate (i.e.
including the whole sample) at the 95\% confidence level. This upper limit
constrains the event rate per magnetar
magnetar yr or, if combined with literature observations of a
similar sample of nearby galaxies, it yields a joint constraint of
magnetar yr. We also provide the first
constraints on the expected rate of FRBs hypothetically originating from
ultraluminous X-ray (ULX) sources, since some of the galaxies observed during
our observational campaign host confirmed ULXs. We obtain yr per
ULX for the total sample of galaxies observed. Our results indicate that bursts
with energies erg from magnetars like SGR J1935+2154 appear more
rarely compared to previous observations and further disfavour them as unique
progenitors for the cosmological FRB population, leaving more space open to the
contribution from a population of more exotic magnetars, not born via
core-collapsed supernovae.Comment: 9 pages, 4 figures, published in A&
Degenerate and non-degenerate parametric excitation in YIG nanostructures
We study experimentally the processes of parametric excitation in microscopic
magnetically saturated disks of nanometer-thick Yttrium Iron Garnet. We show
that, depending on the relative orientation between the parametric pumping
field and the static magnetization, excitation of either degenerate or
non-degenerate magnon pairs is possible. In the latter case, which is
particularly important for applications associated with the realization of
computation in the reciprocal space, a single-frequency pumping can generate
pairs of magnons whose frequencies correspond to different eigenmodes of the
disk. We show that, depending on the size of the disk and the modes involved,
the frequency difference in a pair can vary in the range 0.1-0.8 GHz. We
demonstrate that in this system, one can easily realize a practically important
situation where several magnon pairs share the same mode. We also observe the
simultaneous generation of up to six different modes using a fixed-frequency
monochromatic pumping. Our experimental findings are supported by numerical
calculations that allow us to unambiguously identify the excited modes. Our
results open new possibilities for the implementation of reciprocal-space
computing making use of low damping magnetic insulators.Comment: 18 pages, 4 figure
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