562 research outputs found
AFRICAN MIGRANTS TOWARD INCLUSIVE GROWTH IN MOZAMBIQUE: A CASE STUDY OF THE CITY OF MAPUTO
Migration African scholars have argued that the Migration of Africans is occurring within the continent. That Migrationcan either be intra-regional or inter-regional. South Africa and Northern Africa constitute the core for all Africanimmigration flows; the so-called intra-immigration is made of migration chains such as within the Maghreb region,west, east, and southern Africa. Historically, Mozambique has sent labor to South Africa in plantations and miningfor more than two centuries, while on the other hand, it was seen as a producer of refugees, a Portuguese-speakingcountry, and lower levels of Development indicators. As a consequence, it was a country not desirable to be or tosettle. In the last two decades, the stigma on immigration towards Mozambique is deconstructed because of thebusinesses and jobs opportunities that arose in the country for the boom era of mining, including oil, gas, and coal.The current geography of immigration is made of a multicultural of people from all over the world. A chain of newshops made of construction material, spare car material, barber, boutiques, groceries, and liquor shops are widelyseen in Maputo. Most in containers and owned mainly by African migrants, Chinese, and Mozambicans. Africanmigrants have been portrayed as those who do not add any value to any economy. Instead, they are job stealers.However, the study has demonstrated African’s contribution to economic growth as they give jobs and regularly payrents and taxes. The study is part of MIAG (Migration for Inclusive African Growth) results where interviews andsurveys were used
External gas accretion provides a fresh gas supply to the active S0 galaxy NGC 5077
In early type galaxies, externally accreted gas is thought to be the main
source of gas replenishment at late times. We use MUSE integral field
spectroscopy data to study the active S0 galaxy NGC 5077, known to have
disturbed dynamics, indicative of a past external interaction. We confirm the
presence of a stellar kinematically distinct core with a diameter of 2.8 kpc,
counter-rotating with respect to the main stellar body of the galaxy. We find
that the counter-rotating core consists of an old stellar population, not
significantly different from the rest of the galaxy. The ionised gas is
strongly warped and extends out to 6.5 kpc in the polar direction and in a
filamentary structure. The gas dynamics is complex, with significant changes in
the position angle as a function of radius. The ionised gas line ratios are
consistent with LINER excitation by the AGN both in the nucleus and at
kiloparsec scales. We discover a nuclear outflow with projected velocity V ~
400 km/s, consistent with a hollow outflow cone intersecting the plan of the
sky. The properties of the misaligned gas match predictions from numerical
simulations of misaligned gas infall after a gas-rich merger. The warp and
change in the gas orientation as a function of radius are consistent with gas
relaxation due to stellar torques, that are stronger at small radii where the
gas aligns faster than in the outer regions, driving gas to the nucleus. The
stellar and gas dynamics indicate that NGC 5077 has had at least two external
interactions, one that resulted in the formation of the counter-rotating core
followed by late time external gas accretion. NGC 5077 illustrates the
importance of external interactions in the replenishment of the galaxy gas
reservoir and the nuclear gas content available for black hole fuelling.Comment: Accepted for publication in A&
MUSE observations of a changing-look AGN I: The re-appearance of the broad emission lines
Optical changing-look Active Galactic Nuclei (AGN) are a class of sources
that change type within a short timescale of years or decades. This change is
characterised by the appearance or disappearance of broad emission lines, often
associated with dramatic AGN continuum flux changes that are orders of
magnitude larger than those expected from typical AGN variability. In this work
we study for the first time the host galaxy of a changing-look AGN, Mrk 590,
using high spatial resolution optical and near-infrared observations. We
discover that after ~ 10 yr absence, the optical broad emission lines of Mrk
590 have reappeared. The AGN optical continuum flux however, is still ~ 10
times lower than that observed during the most luminous state in the 1990s. The
host galaxy shows a 4.5 kpc radius star-forming ring with knots of ionised and
cold molecular gas emission. Extended ionised and warm molecular gas emission
are detected in the nucleus, indicating that there is a reservoir of gas as
close as 60 pc from the black hole. We observe a nuclear gas spiral between
radii r ~ 0.5 - 2 kpc, which has been suggested as a dynamical mechanism able
to drive the necessary gas to fuel AGN. We also discover blue-shifted and high
velocity dispersion [O III] emission out to a radius of 1 kpc, tracing a
nuclear gas outflow. The gas dynamics in Mrk 590 suggest a complex balance
between gas inflow and outflow in the nucleus of the galaxy.Comment: Accepted for publication in MNRA
Power generation by unhealthy photovoltaic modules
Hotspots are one of many defects that can occur on degraded photovoltaic system, yielding a detrimental effect on the PV module production. Infrared thermography was used to detect and quantify the severity of hotspots. Temperature difference between overheated and healthy areas was assessed. Four PV modules were analysed, one of them presenting a hotspot. A model for both healthy and unhealthy PV modules was developed, based on the single diode solar cell model and considering, exclusively, data-sheet parameters. To validate the model, the outputs for these working conditions were compared with the real outputs of the studied PV modules, which were previously measured and stored. The relationship between the severity of a hotspot and its respective impact on the power generation of the PV module was studied and the consequent monetary loss can be assessed. Thermographic analysis was enhanced as an optimizing decision-aid tool for the operation of photovoltaic installations.publishersversionpublishe
Avaliação do desempenho acĂşstico de dispositivos de redução do ruĂdo de tráfego
O desenvolvimento urbano que se verificou em Portugal nas Ăşltimas dĂ©cadas do sĂ©culo 20 foi acompanhado por um rápido e elevado crescimento do tráfego e, consequentemente, pela construção de vias rodoviárias quer urbanas quer rurais. A partir do ano 1980, as polĂticas de controlo do ruĂdo levaram as administrações rodoviárias e os construtores a aplicarem medidas de mitigação do ruĂdo que passaram sobretudo pela construção de barreiras acĂşsticas e, em menor grau, pela aplicação de pavimentos com caracterĂsticas que produzem menos ruĂdo. Em ambos os casos, a avaliação do desempenho acĂşstico permite a comparação das especificações de projecto com dados de desempenho reais e a verificação do mesmo a longo prazo para a devida validação das soluções adoptadas.
Neste trabalho apresentam-se os mĂ©todos essenciais para uma gestĂŁo eficaz do ruĂdo rodoviário, que permitem avaliar o ruĂdo de contato pneu-pavimento e o desempenho acĂşstico de dispositivos de redução de ruĂdo do tipo barreiras acĂşsticas. Apresenta-se ainda um mĂ©todo complementar para a determinação da absorção sonora em
pavimentos rodoviários.The urban development that has occurred in Portugal in the last decades of the 20th century was accompanied by a
fast growth of road traffic and, consequently, by the construction of rural and urban roadways. After 1980, the noise
control policies lead the road administrations and constructors to apply noise mitigation measures, like barriers but
also pavements with noise reduction characteristics. In both cases, the evaluation of the acoustic performance allows
a comparison of the design specifications with real performance data and its verification at the long run for an
adequate validation of the adopted solutions. In this work the essential methods for an effective road noise
management that allow the evaluation of road/tyre noise and of the acoustic performance of noise reduction devices,
such as noise barriers. A method for the determination of the sound absorption in road pavements is also presented.Fundação para a Ciência e a Tecnologia (FCT
Sound absorption coefficient of wet gap graded asphalt mixtures
Acoustic absorption properties of materials have often been used to reduce the generation
and propagation of sound. The research carried out in this paper deals with sound absorption
in relation to road surface layers. As the presence of water affects significantly the noise
generated by the tyre-road contact, an evaluation of the sound absorption coefficient was
made to several wet gap-graded mixtures with different levels of porosity and different
contents of rubberized asphalt bitumen. A vacuum device was used to soak the interstices of
the cores with water, which were then tested by means of an impedance tube, according with
standard ISO 10534-2:1998. It was found that the values of the normal incidence sound
absorption coefficient became smeared over the frequency spectrum in comparison with dry
samples and that the quantity of rubber in the asphalt bitumen affected the way water fills the
cores and, consequently, its sound absorption characteristics.(undefined
In situ assessment of the normal incidence sound absorption coefficient of asphalt mixtures with a new impedance tube
Normal incidence sound absorption coefficient of materials is usually calculated with the use
of an impedance tube following the ISO 10534-2 international standard. The same is applied
in the evaluation of the sound absorption characteristics of pavement mixtures. In this
research an impedance tube which was specifically designed to be used in field conditions
has been developed. In order test the tube six asphalt slabs were constructed in laboratory
and its sound absorption coefficient measured with the new impedance tube. Then, several
road sections, with different types of surface, among dense asphalt layers and thin layers,
namely with rubberized asphalt were tested. In this paper, some considerations are made
regarding the performance of the new impedance tube and the sound absorption coefficient
of each asphalt mixtures.(undefined
Influence of pH and a porphyrin ligand on the stability of a G-quadruplex structure within a duplex segment near the promoter region of the SMARCA4 gene
In a previous work, the formation of G-quadruplex structures in a 44-nucleotide long sequence found near the promoter region of the SMARCA4 gene was reported. The central 25 nucleotides were able to fold into an antiparallel G-quadruplex structure, the stability of which was pH-dependent. In the present work, the effect of the presence of lateral nucleotides and the complementary cytosine-rich strand on the stability of this G-quadruplex has been characterized. Moreover, the role of the model ligand TMPyP4 has been studied. Spectroscopic and separation techniques, as well as multivariate data analysis methods, have been used with these purposes. The results have shown that stability of the G-quadruplex as a function of pH or temperature is greatly reduced in the presence of the lateral nucleotides. The influence of the complementary strand does not prevent the formation of the G-quadruplex. Moreover, attempts to modulate the equilibria by an external ligand led us to determine the influence of the TMPyP4 porphyrin on these complex equilibria. This study could eventually help to understand the regulation of SMARCA4 expression
Heterologous Expression of Immature Forms of Human Islet Amyloid Polypeptide in Yeast Triggers Intracellular Aggregation and Cytotoxicity
Funding: iNOVA4Health – UID/Multi/04462/2019, a program financially supported by Fundação para a Ciência e Tecnologia/Ministério da Educação e Ciência, through national funds and co-funded by FEDER under the PT2020 Partnership Agreement is acknowledged. Funding from INTERFACE Programme, through the Innovation, Technology and Circular Economy Fund (FITEC), is gratefully acknowledged. This study was also supported by FCT via PTDC/BIA-MOL31104/2017, UID/Multi/04462/2013- SubProj iNOVA4Health 44, and UID/Multi/04462/2019-SubProj iNOVA4Health C44 to RM, PD/BD/135504/2018 to AR. Sociedade Portuguesa de Diabetologia for the Nuno CasteloBranco Prize – 2016 attributed to RM is also acknowledged.Diabetes is a major public health issue that has attained alarming levels worldwide. Pancreatic aggregates of human islet amyloid polypeptide (IAPP) represent a major histopathological hallmark of type 2 diabetes. IAPP is expressed in β-cells as pre-pro-IAPP (ppIAPP) that is first processed to pro-IAPP (pIAPP) and finally to its mature form (matIAPP), being released upon glucose stimulation together with insulin. Impairment and overload of the IAPP processing machinery seem to be associated with the accumulation of immature IAPP species and the formation of toxic intracellular oligomers, which have been associated with β-cell dyshomeostasis and apoptosis. Nevertheless, the pathological importance of these immature IAPP forms for the assembly and cytotoxicity of these oligomers is not completely understood. Here, we describe the generation and characterization of unprecedented Saccharomyces cerevisiae models recapitulating IAPP intracellular oligomerization. Expression of green fluorescent protein (GFP) fusions of human ppIAPP, pIAPP, and matIAPP proved to be toxic in yeast cells at different extents, with ppIAPP exerting the most deleterious effect on yeast growth and cell viability. Although expression of all IAPP constructs induced the formation of intracellular aggregates in yeast cells, our data point out the accumulation of insoluble oligomeric species enriched in immature ppIAPP as the trigger of the high toxicity mediated by this construct in cells expressing ppIAPP-GFP. In addition, MS/MS analysis indicated that oligomeric species found in the ppIAPP-GFP lysates contain the N-terminal sequence of the propeptide fused to GFP. These models represent powerful tools for future research focused on the relevance of immature forms in IAPP-induced toxicity. Furthermore, they are extremely useful in high-throughput screenings for genetic and chemical modulators of IAPP aggregation.publishersversionpublishe
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