2,546 research outputs found
Statistical translation invariance protects a topological insulator from interactions
We investigate the effect of interactions on the stability of a disordered,
two-dimensional topological insulator realized as an array of nanowires or
chains of magnetic atoms on a superconducting substrate. The Majorana
zero-energy modes present at the ends of the wires overlap, forming a
dispersive edge mode with thermal conductance determined by the central charge
of the low-energy effective field theory of the edge. We show numerically
that, in the presence of disorder, the Majorana edge mode remains
delocalized up to extremely strong attractive interactions, while repulsive
interactions drive a transition to a edge phase localized by disorder.
The absence of localization for strong attractive interactions is explained by
a self-duality symmetry of the statistical ensemble of disorder configurations
and of the edge interactions, originating from translation invariance on the
length scale of the underlying mesoscopic array.Comment: 5+2 pages, 8 figure
Chemical composition, fatty acid and sterol contents of nuts grown in Portugal
Nuts are relevant components of the Mediterranean diet, which is thought to be a healthy one and has been considered as one of the best on coronary heart disease prevention. Although total fat intake is certainly related to health risks, there is now general agreement that the more important issue, where health is concerned, is the type of fat or fatty acids that are consumed. Nuts are also rich in phytosterols, which have been associated with health benefits. Additionally the assessment of identity and quality of vegetable oils obtained from different sources generally involves many tests, including analysis of fatty acids and sterols, once these are probably the most important major and ninor components respectively.
In order to obtain data on composition and nutritional quality of different nuts cultivated in Portugal, different cultivars of hazetnuss (Corylus avellana L.) and walnuts (Juglans regia L.) were analyzed. Chemical composition concerning moisture, total oil content, crude protein, ash and carbohydrates was evaluated. The chemical study also included the determination of sterol and fatty acid compositions. These were determined by gas-liquid chromatography coupled to a flame ionisation detector. Polyunsaturated fatty acids were predominant in walnut samples while monounsaturated were the predominant fatty acids in hazelnuts (beta)-sitosterol, (delta)-avenasterol and campesterol were the major phytosterols in both cases
Fabrication of Poly(Glycerol Sebacate)-Poly(ε-Caprolactone) Extrusion-Based Scaffolds for Cartilage Regeneration
Acknowledgements:
This research was supported by the European Regional Development Fund (FEDER), through COMPETE2020 under the PT2020 program (POCI-01-0145-FEDER-023423), by the Portuguese Foundation for Science and Technology (UID/Multi/04044/2013) and Centro2020 PAMI - ROTEIRO/0328/2013 (Nº 022158).Cartilage related diseases are on the top list concerns of the World Health Organization, being the prevention of articular cartilage degeneration a major health matter for which there are few effective solutions. Using an extrusion-based approach and a polyester elastomer it was aimed to produce 3D structures with controlled architecture and with closer mimicry to cartilage native tissue. The obtained constructs demonstrated high reliability, being the addition of poly (glycerol sebacate) a procedure to enhance the properties of the constructs.info:eu-repo/semantics/publishedVersio
Characterization of several hazelnut (Corylus avellana L.) cultivars based in chemical, fatty acid and sterol composition
Nineteen cultivars of hazelnuts (Corylus avellana L.) collected during the 2001 crop, from Vila Real, Portugal, were analysed for chemical composition, including
moisture, total oil content, crude protein, ash, carbohydrates
and nutritional value. Fat was the predominant
component, ranging from 59.3 to 69.0%. Total oil was extracted
and analysed for fatty acid and sterol compositions
and oxidative stability. Fatty acid and sterol compositions
were determined by Gas–Liquid Chromatography coupled
to a Flame Ionisation Detector (GLC/FID). Monounsaturated
fatty acids, particularly oleic acid, were predominant
(78.7–84.6%). Total phytosterol content ranged from 133.8
to 263.0 mg/100 g of oil. Among the nine sterols identified and quantified, β-sitosterol was the major one with
a mean percentage of 83.6%, while Δ5-avenasterol and
campesterol were the second and the third components of
the group with mean values of 6.1 and 5.8%, respectively.
Since hazelnut oil can be used in olive oil adulteration,
the values obtained were compared with published mean
values of olive oils from different geographical origins
Sterol composition of hazelnuts from different Portuguese cultivars
The consumption of the typicaI Mediterranean diet is associated with lower
mortality rates from coronary heart disease (CHD) and cancer (1 ). This diet is low
in meat and higher in fish, fruits and vegetables, also having nuts as valuable
components. There Is a growing interest in evaluating nut's role in a heart healthy
diet and several studies have been made supporting a role for nuts in
reducing CHD (1 ). Among nut species, hazelnuts are widely appreciated. They
are consumed as a fruit but are also used as an ingredient in confectionary
products. Hazelnuts are rich in phytosterols, which due to their structural
similarity with cholesterol, inhibit its Intestinal absorption, thereby reducing blood
cholesterol. Besides, sterol composition is an important tool in the assessment of
identity and quality of vegetable oils (2). In this work, the sterol composition of
oils extracted from different cultivars of hazelnuts grown in Portugal was
evaluated by gas-liquid chromatography coupled to a flame ionization detector
(GLC/FID). The oil was sap onified and the unsaponifiable fraction was isolated
by solid-phase extraction on an aluminium column
Symmetric arrangement of mitochondria:plasma membrane contacts between adjacent photoreceptor cells regulated by Opa1
Mitochondria are known to play an essential role in photoreceptor function and survival that enables normal vision. Within photoreceptors, mitochondria are elongated and extend most of the inner-segment length, where they supply energy for protein synthesis and the phototransduction machinery in the outer segment, as well as acting as a calcium store. Here, we examined the arrangement of the mitochondria within the inner segment in detail using three-dimensional (3D) electron microscopy techniques and show they are tethered to the plasma membrane in a highly specialized arrangement. Remarkably, mitochondria and their cristae openings align with those of neighboring inner segments. The pathway by which photoreceptors meet their high energy demands is not fully understood. We propose this to be a mechanism to share metabolites and assist in maintaining homeostasis across the photoreceptor cell layer. In the extracellular space between photoreceptors, Müller glial processes were identified. Due to the often close proximity to the inner-segment mitochondria, they may, too, play a role in the inner-segment mitochondrial arrangement as well as metabolite shuttling. OPA1 is an important factor in mitochondrial homeostasis, including cristae remodeling; therefore, we examined the photoreceptors of a heterozygous Opa1 knockout mouse model. The cristae structure in the Opa1+/− photoreceptors was not greatly affected, but the mitochondria were enlarged and had reduced alignment to neighboring inner-segment mitochondria. This indicates the importance of key regulators in maintaining this specialized photoreceptor mitochondrial arrangement
In vitro inhibition of linoleic acid peroxidation by primary S-nitrosothiols
Nitric oxide ( NO) is an effective chain-breaking antioxidant in the inhibition of lipid peroxidation and circulates in vivo mainly as primary S-nitrosothiols (RSNOs). In this work, the in vitro peroxidation of linoleic acid-SDS comicelles (LA-SDS) catalyzed by soybean lipoxygenase (SLO) and FeII ions was monitored in the presence and absence of three primary RSNOs: S-nitrosocysteine, S-nitroso-N-acetylcysteyne and S-nitrosoglutathione. Kinetic measurements based on the formation of conjugated double bonds and fluorescent oxidized LA-lysine adducts, showed that RSNOs are more potent antioxidants than their corresponding free thiols (RSHs) in equimolar conditions. These results are consistent with the blocking of LA-SDS peroxidation by RSNOs through the inactivation of peroxyl/alkoxyl (LOO /LO ) radicals, leading to nitrogen-containing products of oxidized LA, which release free NO. These results indicate that endogenous RSNOs may play a major role in the blocking of lipid peroxidation in vivo, through the primary inactivation of alkoxyl/peroxyl radicals and also of preformed lipid hydroperoxides.O óxido nítrico ( NO) é um antioxidante efetivo na inibição da peroxidação lipídica e circula in vivo principalmente como S-nitrosotióis primários (RSNOs). Neste trabalho, a peroxidação in vitro de comicelas do ácido linileico-SDS (LA-SDS) catalisada por lipoxigenase de soja (SLO) e íons FeII foi monitorada na presença e na ausência de três RSNOs: S-nitrosocisteína, S-nitroso-N-acetilcisteína e S-nitrosoglutationa. Medidas cinéticas baseadas na formação de duplas ligações conjugadas e adutos fluorescentes de lisina-La oxidado mostraram que os RSNOs são antioxidantes mais potentes que seus tióis livres (RSHs) correspondentes em condições equimolares. Esses resultados são consistentes com o bloqueio da peroxidação de LA-SDS por RSNOs através da inativação dos radicais peroxila/alcoxila (LOO /LO ), levando a produtos nitrogenados do LA oxidado, os quais liberam NO. Esses resultados indicam que os RSNOs endógenos podem desempenhar um papel importante no bloqueio da peroxidação lipídica in vivo, através da inativação primária de radicais alcoxila/peroxila bem como de hidroperóxidos lipídicos pré-formados.18851895Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
To practice or not to practice? Designing higher education curriculum to boost employability
One important dimension of Higher education curriculum design pertains to the inclusion of internships in study programmes. These have been generally conceptualized as learning experiences capable of bridging theoretical knowledge and hands-on experiences. The underlying pedagogical relevance is based on the premise that internships create the possibility of contextualized learning, fostering both professional growth and students’ self-esteem and pro-activity (Little, 2006). Interns are provided with the opportunity of early networking, as they enrol in practical activities and professionally interact with other people, besides their academic teachers and their graduate colleagues (Alpert, Heaney, & Kuhn, 2009; Weible, 2009).
Research concerning internships has extensively reported the overwhelming positive effect of internships. Nevertheless, a more recent trend in literature has argued that little has been said concerning the relationship between internships and graduate employment or employability. Wilton (2012), for example, argues that more needs to be understood about the characteristics and specificities of internships and the extent to which such characteristics are capable of overcoming the current concern over the increase of graduates’ unemployment rates.
Research conducted on the Portuguese case based on a database of 1,168 study programmes of first cycle degrees sough to redress this gap. Besides demonstrating that study programmes which include internships (cooperative education) tend to generate lower levels of unemployment than those that do not include internships, this research has suggested that the nature and structure of internships significantly impacts on graduate unemployment rates. In specific, mandatory internships tend to outperform their optional counterpart in reducing graduate unemployment levels. Moreover, thin sandwich courses also seem to be more beneficial than thick sandwich courses, suggesting that expanding and diversifying internships throughout the curriculum can reduce graduate unemployment rates. These results strongly suggest that it is not (only) the internship learning experience per se that makes the difference considering graduate employability, but (also) the way those internship experiences are organized along the study programme.
This poster is, thus, focused on the nature and structure of internships, assessing their implications for higher education curriculum design. It does so by exploring the perspectives of the main stakeholders involved in internships regarding their motivations; required efforts; and expected outcomes.
Empirically, the poster is based on the content analysis of semi-structured individual interviews to units coordinators and also focus groups conducted with coordinators of study programmes; internship supervisors (both academics and employers); and also interns. Qualitative analysis has been sustained by the main learning models traditionally used in research on work-based learning and aims at identifying a set of principles related with internships design, and modes of embedding them along an entire course, which may contribute to the development of graduates’ employability.
Reported findings may constitute an important primer for reflection on the design of pedagogical strategies that maximize the contextual learning outputs of internships in a more systematic way, being particularly relevant for leading academics, namely those involved in curriculum design
Smartphones: el sistema nervioso de la comunicación líquida
A utilização das novas tecnologias móveis tornou-se um fenómeno global. Existe “uma cultura jovem móvel global” e uma “emergência da sociabilidade em rede” (Castells et al., 2009: 183-184). O objetivo deste estudo passou por compreender a utilização dos telemóveis pelos millennials, que gratificações procuram e os efeitos
sociais gerados pela utilização destes equipamentos. O trabalho desenvolvido, através de uma metodologia mista que reuniu a investigação quantitativa e qualitativa, compreendeu a análise de 649 questionários a jovens adultos e 46 posts das páginas da rede social Facebook, dos principais operadores do setor das telecomunicações, em Portugal. O efeito da vivência da experiência de fluxo, entre outros resultados revelados pelo modelo de equações estruturais, poderá servir de advertência para os próprios utilizadores, pais, empresas e escolas que funcionam como mediadores do ensino da linguagem, através das novas tecnologias.This work was supported by national funds through the FCT- Fundação para a Ciência e Tecnologia. I.P., (Project UID/Multi/04016/2016, Project UID/ECO/00124/2013 and by POR-Lisboa, under the project Lisboa-01-0145-FEDER-007722). In addition, we also want to thank the Polytechnic Institute of Viseu and CI &DETS for their support.info:eu-repo/semantics/publishedVersio
Spatial and temporal distribution of cetaceans in the mid-Atlantic waters around the Azores
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Taylor & Francis for personal use, not for redistribution. The definitive version was published in Marine Biology Research 10 (2014): 123-137, doi:10.1080/17451000.2013.793814.Cetaceans living in offshore waters are under increasing pressure from anthropogenic
activities. Yet, due to the lack of survey effort, relatively little is known about the
demography or ecology of these populations. Spatial and temporal distribution of
cetaceans in mid-Atlantic waters were investigated using a long term dataset collected
from boat surveys and land-based observations around the Azores. From 1999 to
2009, 7307 cetacean schools were sighted during 271717 km of survey effort. In 4944
h of land-based observations, 2968 cetacean groups were detected. Twenty-four
species were recorded: seven baleen whales, six beaked whales, eight dolphin species,
Physeter macrocephalus, Kogia breviceps and K. sima. Overall, Delphinus delphis
was the most frequently sighted species but its encounter rate decreased in June-
November, coinciding with presence of Stenella frontalis in the region. Tursiops
truncatus, P. macrocephalus and Grampus griseus were frequently encountered yearround,
whereas large baleen whales showed a distinct peak in encounter rates in
March-May. Mesoplodonts were fairly common and appear to be present throughout
the year. These findings fill-in a significant gap in the knowledge of cetaceans
occurring in a poorly studied region of the North Atlantic, providing much needed
data to inform management initiatives.This work
was supported by FEDER funds, through the Competitiveness Factors Operational
Programme – COMPETE, by national funds, through FCT – Foundation for Science
and Technology, under projects CETAMARH (POCTI/BSE/38991/01) and TRACE
(PTDC/MAR/74071/2006), and by regional funds, through DRCT/SRCTE, under
project MAPCET (M2.1.2/F/012/2011). We thank the Azorean Regional Government
for funding POPA, the Shipowners Proprietors and the Association of the Tuna
Canning Industries for their support to the programme. MAS was supported by an
FCT postdoctoral grant (SFRH/BPD/29841/2006), and IC and RP were supported by
doctoral grants SFRH/BD/41192/2007 and SFRH/BD/32520/2006. IMAR-DOP/UAç
is the R&D Unit #531 and part of the Associated Laboratory #9 (ISR) funded through
the pluri-annual and programmatic funding schemes of FCT-MCTES and DRCTAzores
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