456 research outputs found
On the stability around Chariklo and the confinement of its rings
Chariklo has two narrow and dense rings, C1R and C2R, located at 391 km and
405 km, respectively. In the light of new stellar occultation data, we study
the stability around Chariklo. We also analyse three confinement mechanisms, to
prevent the spreading of the rings, based on shepherd satellites in resonance
with the edges of the rings. This study is made through a set of numerical
simulations and the Poincar\'e surface of section technique. From the numerical
simulation results we verify that, from the current parameters referring to the
shape of Chariklo, the inner edge of the stable region is much closer to
Chariklo than the rings. The Poincar\'e surface of sections allow us to
identify the first kind periodic and quasi-periodic orbits, and also the
resonant islands corresponding to the 1:2, 2:5, and 1:3 resonances. We
construct a map of a versus e space which gives the location and width of the
stable region and the 1:2, 2:5, and 1:3 resonances. We found that the first
kind periodic orbits family can be responsible for a stable region whose
location and size meet that of C1R, for specific values of the ring particles'
eccentricities. However, C2R is located in an unstable region if the width of
the ring is assumed to be about 120 m. After analysing different systems we
propose that the best confinement mechanism is composed of three satellites,
two of them shepherding the inner edge of C1R and the outer edge of C2R, while
the third satellite would be trapped in the 1:3 resonance.Comment: Accepted for publication in Astronomy & Astrophysic
A rapid and low-cost nonlithographic method to fabricate biomedical microdevices for blood flow analysis
Microfluidic devices are electrical/mechanical systems that offer the ability to
work with minimal sample volumes, short reactions times, and have the possibility to
perform massive parallel operations. An important application of microfluidics is blood
rheology in microdevices, which has played a key role in recent developments of lab-on-chip
devices for blood sampling and analysis. The most popular and traditional method to
fabricate these types of devices is the polydimethylsiloxane (PDMS) soft lithography
technique, which requires molds, usually produced by photolithography. Although the
research results are extremely encouraging, the high costs and time involved in the
production of molds by photolithography is currently slowing down the development cycle
of these types of devices. Here we present a simple, rapid, and low-cost nonlithographic
technique to create microfluidic systems for biomedical applications. The results demonstrate
the ability of the proposed method to perform cell free layer (CFL) measurements and the
formation of microbubbles in continuous blood flow.The authors acknowledge the financial support provided by PTDC/SAU-BEB/105650/2008,
PTDC/SAU-ENB/116929/2010, EXPL/EMS-SIS/2215/2013 and scholarship SFRH/BD/89077/2012 and SFRH/BD/97658/2013 from FCT (Science and Technology Foundation), COMPETE, QREN and
European Union (FEDER).info:eu-repo/semantics/publishedVersio
Haemocompatibility of iron oxide nanoparticles synthesized for theranostic applications: a high-sensitivity microfluidic tool
The poor heating efficiency of the most
reported magnetic nanoparticles (MNPs), allied to the
lack of comprehensive biocompatibility and haemodynamic
studies, hampers the spread of multifunctional
nanoparticles as the next generation of
therapeutic bio-agents in medicine. The present work
reports the synthesis and characterization, with special
focus on biological/toxicological compatibility, of
superparamagnetic nanoparticles with diameter
around 18 nm, suitable for theranostic applications
(i.e. simultaneous diagnosis and therapy of cancer).
Envisioning more insights into the complex nanoparticle-red
blood cells (RBCs) membrane interaction,
the deformability of the human RBCs in contact with
magnetic nanoparticles (MNPs) was assessed for the
first time with a microfluidic extensional approach,
and used as an indicator of haematological disorders in
comparison with a conventional haematological test,
i.e. the haemolysis analysis. Microfluidic results
highlight the potential of this microfluidic tool over
traditional haemolysis analysis, by detecting small
increments in the rigidity of the blood cells, when
traditional haemotoxicology analysis showed no significant
alteration (haemolysis rates lower than 2 %).
The detected rigidity has been predicted to be due to
the wrapping of small MNPs by the bilayer membrane
of the RBCs, which is directly related to MNPs size,
shape and composition. The proposed microfluidic
tool adds a new dimension into the field of
nanomedicine, allowing to be applied as a highsensitivity
technique capable of bringing a better understanding of the biological impact of nanoparticles
developed for clinical applications.This work was financially supported by:
Project POCI-01-0145-FEDER-006984 – Associate Laboratory
J Nanopart Res (2016) 18:194 Page 15 of 17 194
123 LSRE-LCM funded by FEDER funds through COMPETE2020 -
Programa Operacional Competitividade e Internacionalizac¸a˜o
(POCI) – and by national funds through FCT - Fundac¸a˜o para a
Cieˆncia e a Tecnologia. R.O.R. acknowledges the Ph.D.
scholarship SFRH/BD/97658/2013 Granted by FCT. A.M.T.S
acknowledges the FCT Investigator 2013 Programme (IF/01501/
2013), with financing from the European Social Fund and the
Human Potential Operational Programme. M.B. would like to
thank ERDF (European Regional Development Fund) under
grant PO Norte CCDR-N/ON.2 Programme. J.G. also thanks the
European Union’s Seventh Framework Programme for research,
technological development and demonstration under grant
agreement no. 600375.info:eu-repo/semantics/publishedVersio
Percoll® e optiprep® como mini gradientes para seleção espermática no sistema de produção in vitro de embriões bovinos.
Influência de diferentes gradientes de densidade na seleção espermática para a produção in vitro de embriões bovinos das raças angus e jersey.
Loss of a globally unique kelp forest from Oman
Kelp forests are declining in many regions globally with climatic perturbations causing shifts to alternate communities and significant ecological and economic loss. Range edge populations are often at most risk and are often only sustained through localised areas of upwelling or on deeper reefs. Here we document the loss of kelp forests (Ecklonia radiata) from the Sultanate of Oman, the only confirmed northern hemisphere population of this species. Contemporary surveys failed to find any kelp in its only known historical northern hemisphere location, Sadah on the Dhofar coast. Genetic analyses of historical herbarium specimens from Oman confirmed the species to be E. radiata and revealed the lost population contained a common CO1 haplotype found across South Africa, Australia and New Zealand suggesting it once established through rapid colonisation throughout its range. However, the Omani population also contained a haplotype that is found nowhere else in the extant southern hemisphere distribution of E. radiata. The loss of the Oman population could be due to significant increases in the Arabian Sea temperature over the past 40 years punctuated by suppression of coastal upwelling. Climate-mediated warming is threatening the persistence of temperate species and precipitating loss of unique genetic diversity at lower latitudes.info:eu-repo/semantics/publishedVersio
Basic self-disturbances related to reduced anterior cingulate volume in subjects at ultra-high risk for psychosis
Introduction: Alterations of the “pre-reflective” sense of first-person perspective (e.g., of the “basic self”) are characteristic features of schizophrenic spectrum disorders and are significantly present in the prodromal phase of psychosis and in subjects at ultra-high risk for psychosis (UHR). Studies in healthy controls suggest that neurobiological substrate of the basic self involves cortical midline structures, such as the anterior and posterior cingulate cortices. Neuroimaging studies have identified neuroanatomical cortical midline structure abnormalities in schizophrenic spectrum disorders.
Objectives: i) To compare basic self-disturbances levels in UHR subjects and controls and ii) to assess the relationship between basic self-disturbances and alterations in cortical midline structures volume in UHR subjects.
Methods: Thirty-one UHR subjects (27 antipsychotic-naïve) and 16 healthy controls were assessed using the 57-item semistructured Examination of Anomalous Self-Experiences (EASE) interview. All subjects were scanned using magnetic resonance imaging (MRI) at 3 T, and gray matter volume was measured in a priori defined regions of interest (ROIs) in the cortical midline structures.
Results: EASE scores were much higher in UHR subjects than controls (p < 0.001). The UHR group had smaller anterior cingulate volume than controls (p = 0.037). There were no structural brain imaging alterations between UHR individuals with or without self-disturbances. Within the UHR sample, the subgroup with higher EASE scores had smaller anterior cingulate volumes than UHR subjects with lower EASE scores and controls (p = 0.018). In the total sample, anterior cingulate volume was inversely correlated with the EASE score (R = 0.52, p < 0.016).
Conclusions: Basic self-disturbances in UHR subjects appear to be related to reductions in anterior cingulate volume
Investigación en Progreso: Ingeniería de Software en el Desarrollo de Aplicaciones Sensibles al Contexto
Las aplicaciones han ido evolucionando independientemente de cuál sea su dominio de aplicación, actualmente nos encontramos con aplicaciones que pueden brindar servicios de acuerdo a la ubicación, tiempo y perfil del usuario. Este tipo de aplicaciones que brindan estos servicios se las conoce como Aplicaciones Sensibles al Contexto (CA – Context Aware), en este tipo de aplicaciones predominan los dispositivos móviles y el perfil del usuario. La evolución varía en función de la forma de uso de la computadora, es decir que se brinden servicios a pedido del usuario o que se brinden servicios de manera automática. Para acompañar la evolución de este tipo de aplicaciones, la Ingeniería de Software ha focalizado sus esfuerzos en aspectos relacionados a separar la aplicación de todo lo concerniente a la captación, interpretación, control y supervisión de la información contextual. Es decir que desde el punto de vista del diseño, se separe la conducta sensible al contexto de la conducta propia de la aplicación con el propósito de que ambos tipos de aplicaciones pueden evolucionar en forma independiente además de reducir el tiempo de desarrollo en este tipo de sistemas. Este proyecto presenta una sub línea, la cual orientará sus aportes, en la consolidación de un framework de gestión contextual de dos o tres variables de contexto como por ejemplo: la ubicación, considerando la construcción de la documentación relevante que lo respalde como así también su fase de experimentación con una aplicación que permitirá a los usuarios de la comunidad universitaria UM hacer uso de los servicios ofrecidos por la misma. La segunda sub línea, se vincula al Área de la Ingeniería de Requisitos, pretendiendo obtener un modelo para la especificación de requisitos de software para sistemas sensibles al contexto
Inventory and review of the Mio–Pleistocene São Jorge flora (Madeira Island, Portugal): palaeoecological and biogeographical implications
The occurrence of plant fossils on Madeira Island has been known since the mid-nineteenth century. Charles Lyell and
George Hartung discovered a leaf bed rich in Lauraceae and fern fossils at S~ao Jorge in 1854. The determinations were
controversial but a full review was never performed. Here we propose possible geological settings for the fossiliferous
outcrop, and present an inventory and a systematic review of the surviving specimens of the S~ao Jorge macroflora. The S~ao
Jorge leaf bed no longer outcrops due to a landslide in 1865. It was possible to establish the two alternative volcano stratigraphical settings in the sedimentary intercalations from the Middle Volcanic Complex, ranging in age from 7 to
1.8 Ma. The descriptions of Heer (1857), Bunbury (1859) and Hartung & Mayer (1864) are reviewed based on 82
surviving specimens. From the initial 37 taxa, we recognize only 20: Osmunda sp., Pteridium aquilinum, Asplenium cf.
onopteris, aff. Asplenium, cf. Polystichum, cf. Davallia, Woodwardia radicans, Filicopsida gen. et sp. indet. 1 and 2,
Ocotea foetens, Salix sp., Erica arborea, cf. Vaccinium, Rubus sp, cf. Myrtus, Magnoliopsida gen. et sp. indet. 1 to 3,
Liliopsida gen. et sp. indet. 1. Magnoliopsida gen. et sp. indet. 4 is based on one previously undescribed flower or fruit.
The floristic composition of the S~ao Jorge fossils resembles the current floristic association of temperate stink laurel
(Ocotea foetens) forest, suggesting a warm and humid palaeoclimate and indicating that laurel forests were present in
Macaronesia at least since the Gelasian, a time when the palaeotropical geofloral elements were almost extinct in Europe.info:eu-repo/semantics/publishedVersio
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