122 research outputs found
An Enhanced Reservation-Based MAC Protocol for IEEE 802.15.4 Networks
The IEEE 802.15.4 Medium Access Control (MAC) protocol is an enabling standard for wireless sensor networks. In order to support applications requiring dedicated bandwidth or bounded delay, it provides a reservation-based scheme named Guaranteed Time Slot (GTS). However, the GTS scheme presents some drawbacks, such as inefficient bandwidth utilization and support to a maximum of only seven devices. This paper presents eLPRT (enhanced Low Power Real Time), a new reservation-based MAC protocol that introduces several performance enhancing features in comparison to the GTS scheme. This MAC protocol builds on top of LPRT (Low Power Real Time) and includes various mechanisms designed to increase data transmission reliability against channel errors, improve bandwidth utilization and increase the number of supported devices. A motion capture system based on inertial and magnetic sensors has been used to validate the protocol. The effectiveness of the performance enhancements introduced by each of the new features is demonstrated through the provision of both simulation and experimental results
Design and implementation of a wireless sensor network applied to motion capture
This paper describes the development of a wireless sensor network prototype and its application in a motion capture system based on inertial and magnetic sensors. The system presents a portable and modular architecture and allows the monitoring of several users at the same time using a single wireless network. The target application requires the wireless sensor network to operate efficiently under high loads, since it generates data intensive traffic and needs to support a high number of sensor modules. Other requirements imposed by the application are real-time operation and reliable data delivery. In order to provide the quality of service required by the application, an enhanced version of the LPRT medium access control protocol was developed and implemented in devices compliant with the IEEE 802.15.4 standard at the physical layer. Simulation results show that the proposed modifications improve the performance of the protocol. The implementation of the protocol is validated through the experimental results presented.Fundação para a Ciência e a Tecnologia (FCT) - projeto
PTDC/EEA-TEL/68625/2006
Avaliação do grau de satisfação da utilização do Sistema Intrauterino hormonal de Levonorgestrel 13,5 mg
Metabolic plasticity for subcutaneous fat accumulation in a long-distance migratory bird traced by 2 H 2 O
The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium (2H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16- and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and non-lethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and cost-effective.The authors acknowledge financial support from Fundacao para a Ciencia e Tecnologia (FCT) in the form of fellowships to I.V. (SFRH/BPD/90032/2012), P.M.A. (SFRH/BD/69238/2010), A.D.R. (SFRH/BD/74228/2010) and J.A.A. (SFRH/BPD/91527/2012) and research project EXCL/DTP-PIC/0069/2012. NMR data were collected at the UC-NMR facility that is supported by FEDER and FCT (RECI/QEQ-QFI/0168/2012, CENTRO-07-CT62-FEDER-002012) and Rede Nacional de Ressonancia Magnetica Nuclear (RNRMN).Peer Reviewe
Fecal Dipeptidyl Peptidase-4: An Emergent Biomarker in Inflammatory Bowel Disease
INTRODUCTION: Dipeptidyl peptidase-4 (DPP-4) is a membrane-bound glycoprotein that acts as a receptor but also exists in a soluble form. It has been recognized as a mediator of inflammation and considered a biomarker in inflammatory bowel disease (IBD). METHODS: We evaluated a prospectively recruited cohort, consisting of 101 patients with IBD, using validated clinical indexes; 22 patients with ulcerative colitis (UC) underwent endoscopic evaluation. Fecal DPP-4 (fDPP-4) levels were analyzed and correlated with clinical scores, Mayo endoscopic score (in UC patients), serum DPP-4, C-reactive protein, and fecal calprotectin. Immunohistochemical staining for DPP-4 in intestinal biopsies was also performed. RESULTS: When compared with remitters, median fDPP-4 levels were higher in patients with ileal Crohn's disease (CD) (7,584 [1,464-7,816] vs 2,104 [630-2,676] ng/mL, P = 0.015) and lower in patients with UC exhibiting clinical activity (1,213 [559-1,682] vs 7,814 [2,555-7,985] ng/mL, P < 0.001). Patients with UC presenting endoscopic activity also had lower levels than remitters (939 [559-1,420] vs 7,544 [4,531-7,940] ng/mL, P = 0.006). Fecal DPP-4 discriminated clinical activity from remission with areas under the curve of 0.76 (95% confidence interval [CI] 0.58-0.94, P = 0.015) and 0.80 (95% CI 0.68-0.93, P < 0.001) in CD and UC, respectively; it allowed to differentiate endoscopic activity in patients with UC, with areas under the curve of 0.84 (95% CI 0.63-1.00, P = 0.009). Immunohistochemical analysis revealed higher DPP-4 apical expression in UC remitters, but no statistically significant differences were revealed between patients with ileal CD. DISCUSSION: Our results suggest that fDPP-4 can be used as a biomarker of IBD activity, particularly in UC. The expression profiles in intestinal tissue might represent a functional compartmentalization of DPP-4 expression
Understanding how birds rebuild fat stores during migration: insights from an experimental study
Publisher's version (útgefin grein).Mechanisms underlying fat accumulation for long-distance migration are not fully understood. This
is especially relevant in the context of global change, as many migrants are dealing with changes in
natural habitats and associated food sources and energy stores. The continental Black-tailed godwit
Limosa limosa limosa is a long-distance migratory bird that has undergone a considerable dietary shift
over the past few decades. Historically, godwits fed on an animal-based diet, but currently, during the
non-breeding period godwits feed almost exclusively on rice seeds. The latter diet may allow building
up of their fuel stores for migration by signifcantly increasing de novo lipogenesis (DNL) activity. Here,
we performed an experiment to investigate lipid fux and the abundance of key enzymes involved in
DNL in godwits, during fasting and refueling periods at the staging site, while feeding on rice seeds or
fy larvae. Despite no signifcant diferences found in enzymatic abundance (FASN, ME1, ACC and LPL)
in stored fat, experimental godwits feeding on rice seeds presented high rates of DNL when compared
to fy-larvae fed birds (~35 times more) and fasted godwits (no DNL activity). The increase of fractional
DNL in godwits feeding on a carbohydrate-rich diet can potentially be enhanced by the fasting period
that stimulates lipogenesis. Although requiring further testing, these recent fndings provide new
insights into the mechanisms of avian fat accumulation during a fasting and refueling cycle and
associated responses to habitat and dietary changes in a migratory species.Te authors acknowledge fnancial support from Fundação para a Ciencia e Tecnologia (FCT) in the form of
fellowships to PMA (SFRH/BD/69238/2010), IV (SFRH/BPD/90032/2012) and JAA (SFRH/BPD/91527/2012)
and research Project CGL2017-89009-P. NMR data were collected at the UC-NMR facility that is supported
by FEDER and FCT (RECI/QEQ-QFI/0168/2012, CENTRO-07-CT62-FEDER-002012) and Rede Nacional
de Ressonancia Magnética Nuclear (RNRMN). Tis study benefted from funding by the strategic program of
MARE, fnanced by FCT (UID/MAR/04292/2019), and by FTC/MCTES to CESAM, (UID/AMB/50017 – POCI01-0145-FEDER-007638), through national funds.Peer Reviewe
The physical properties of star forming galaxies in the low redshift universe
(modified) We present a comprehensive study of the physical properties of
\~10^5 galaxies with measurable star formation in the SDSS. By comparing
physical information extracted from the emission lines with continuum
properties, we build up a picture of the nature of star-forming galaxies at
z<0.2. We take out essentially all aperture bias using resolved imaging,
allowing an accurate estimate of the total SFRs in galaxies. We determine the
SFR density to be 1.915^{+0.02}_{-0.01}(rand.)^{+0.14}_{-0.42} (sys.) h70
10^{-2} Msun/yr/Mpc^3 at z=0.1 (for a Kroupa IMF) and we study the distribution
of star formation as a function of various physical parameters. The majority of
the star formation in the low redshift universe takes place in moderately
massive galaxies (10^10-10^11 Msun), typically in HSB disk galaxies. Roughly
15% of all star formation takes place in galaxies that show some sign of an
active nucleus. About 20% occurs in starburst galaxies. We show that the
present to past-average star formation rate, the Scalo b-parameter; is almost
constant over almost three orders of magnitude in mass, declining only at
M*>10^10 Msun. The volume averaged b parameter is 0.408^{+0.005}_{-0.002}
(rand).^{+0.029}_{-0.090} (sys.) h70^{-1}. We use this value constrain the star
formation history of the universe. In agreement with other work we find a
correlation between and morphological type, as well as a tight correlation
between the 4000AA break (D4000) and b. We discuss how D4000 can be used to
estimate b parameters for high redshift galaxies.Comment: Accepted for MNRAS. Replaced with accepted version. A section on
comparison with other methods of SFR estimation added and various updates
have been made. The main results are almost unchange
Metabolic plasticity for subcutaneous fat accumulation in a long-distance migratory bird traced by 2H2O
La comilona migratoria de cola negra (Limosa limosa) tradicionalmente utilizaba humedales naturales en la Península Ibérica para prepararse para los vuelos migratorios alimentándose principalmente en estuarios. En las últimas décadas, esta especie se ha vuelto cada vez más dependiente de los campos de arroz, confiando así en una dieta basada en plantas para alimentar. Los ácidos grasos en la dieta (FA) parecen ser determinantes para la composición de la grasa subcutánea acumulada en las aves migratorias. Aún no está claro si la plasticidad metabólica permite la modificación y / o síntesis de la FA, lo que contribuye a un perfil lipídico que permite un rendimiento migratorio exitoso. El agua deuterada se administró a las monitas de cola negra cautivas sometidas a dos dietas (larvas de mosca versus arroz) y se analizó la incorporación de deuterio (2H) en los triglicéridos subcutáneos mediante RMN. Un método de biopsia localizada recientemente desarrollado para muestrear grasa subcutánea se empleó con la posterior liberación exitosa de todas las aves en el medio silvestre. La estructura química promedio reflejó principalmente una mezcla de FA saturada y monoinsaturada de 16 y 18 carbonos, un perfil que se encuentra con frecuencia en las aves migratorias. Se observaron niveles significativamente más altos de FA poliinsaturada, así como niveles detectables de FA n-3, en aves alimentadas con larvas de mosca. El exceso de enriquecimiento con 2H en FA reveló tasas significativamente más altas de lipogénesis de novo fraccional y capacidad de desaturación de FA en aves alimentadas con arroz. Este novedoso y no letal método trazador reveló la capacidad de esta especie para alterar su metabolismo lipídico para compensar una contribución de lípidos en la dieta más deficiente. Debido a su versatilidad, la adaptación de este método a otros escenarios y / u otras especies migratorias se considera factible y rentable.The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium (2H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16- and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and nonlethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and costeffective.• Fundação para a Ciência e Tecnologia. Beca SFRH / BPD / 90032/2012, para Iván Daniel dos Santos Martins Viegas
• Fundação para a Ciência e Tecnologia. Beca SFRH / BD / 69238/2010, para Pedro Miguel Mendes Araujo
• Fundação para a Ciência e Tecnologia. Beca SFRH / BD / 74228/2010, para Afonso D. Rocha
• Fundação para a Ciência e Tecnologia. Beca SFRH / BPD / 91527/2012, para José Albino Alves
• Fundação para a Ciência e Tecnologia. Proyecto de investigación EXCL / DTP-PIC / 0069/2012peerReviewe
Long-term declines of wader populations at the Tagus estuary, Portugal: A response to global or local factors?
Migratory wader populations face global threats, mainly related to increasing rates of habitat loss
and disturbance driven by human activities. To a large extent, the long-term survival of these
populations requires the conservation of networks of sites along their migratory flyways. The
Tagus estuary, Portugal, is among the most important wetlands for waders in the East Atlantic
Flyway. Annual winter wader counts have been carried in this wetland since 1975 and a monthly
roost-monitoring programme was implemented in 2007. Wintering populations of three out of
the five most abundant species, Dunlin Calidris alpina, Grey Plover Pluvialis squatarola and
Redshank Tringa totanus, showed significant population declines over the past three decades,
which are most likely due to the loss and degradation of roost sites as a result of increasing
human activity. The situation is unlikely to improve, as a high proportion of the wintering
waders use roost sites that are situated in highly urbanised areas with no legal protection. The use
of different roost sites by waders is highly variable both temporally and spatially, thus
emphasizing the need for a network of good quality roost sites. Additionally, during migration,
60–80% of all the waders of the Tagus estuary concentrate at a single refuge, thus increasing the
risk for wader populations during these periods. ------ RESUMO ------ As populações de aves limícolas migradoras enfrentam ameaças globais, maioritariamente
relacionadas com a crescente perda de habitat e perturbação humana. Para garantir a sobrevivência
a longo-termo destas populações é imprescindível a conservação de uma rede de áreas húmidas ao
longo das suas rotas migratórias. O estuário do Tejo, em Portugal, é uma das mais importantes
áreas húmidas para aves limícolas na rota Migratória do Atlântico Este. Desde 1975, foram
efectuadas contagens anuais de aves limícolas no inverno nesta zona húmida e, em 2007, foi implementado
um programa de monitorização mensal dos refúgios de preia-mar. As populações invernantes
de três das cinco espécies de limícolas mais abundantes no estuário, o Pilrito-de-peito-preto
Calidris alpina, a Tarambola-cinzenta Pluvialis squatarola e o Perna-vermelha Tringa totanus,
mostraram tendências significativas de decréscimo nas últimas três décadas, potencialmente
devido à degradação e perda de refúgios como resultado da crescente actividade antropogénica.
Esta situação poderá deteriorar-se, uma vez que uma grande proporção das aves limícolas
invernantes utiliza refúgios em áreas densamente urbanizadas sem qualquer estatuto legal de protecção. A utilização dos diferentes refúgios do estuário do Tejo por aves limícolas tem uma
grande variação espacial e temporal, o que reforça a importância da existência de uma rede de
refúgios de elevada qualidade nesta área húmida. Durante a migração, 60 a 80% das aves
limícolas concentram-se num único refúgio, ficando assim particularmente vulneráveis neste
período
Influenza Virus Ribonucleoprotein Complexes Gain Preferential Access to Cellular Export Machinery through Chromatin Targeting
In contrast to most RNA viruses, influenza viruses replicate their genome in the nucleus of infected cells. As a result, newly-synthesized vRNA genomes, in the form of viral ribonucleoprotein complexes (vRNPs), must be exported to the cytoplasm for productive infection. To characterize the composition of vRNP export complexes and their interplay with the nucleus of infected cells, we affinity-purified tagged vRNPs from biochemically fractionated infected nuclei. After treatment of infected cells with leptomycin B, a potent inhibitor of Crm1-mediated export, we isolated vRNP export complexes which, unexpectedly, were tethered to the host-cell chromatin with very high affinity. At late time points of infection, the cellular export receptor Crm1 also accumulated at the same regions of the chromatin as vRNPs, which led to a decrease in the export of other nuclear Crm1 substrates from the nucleus. Interestingly, chromatin targeting of vRNP export complexes brought them into association with Rcc1, the Ran guanine exchange factor responsible for generating RanGTP and driving Crm1-dependent nuclear export. Thus, influenza viruses gain preferential access to newly-generated host cell export machinery by targeting vRNP export complexes at the sites of Ran regeneration
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