539 research outputs found
O ensino das ciências experimentais no liceu, em Portugal, na I República (1910-1926)
O ensino das ciências experimentais (ECE) em Portugal ficou, como pretendemos demonstrar, fortemente marcado pela instauração da República, que comemorou no ano transacto o seu centenário. A República de 1910 pretendeu reformar toda a mentalidade portuguesa, através do pilar base – a educação – pela qual seria capaz de sacudir a nossa maneira de ser, lançando desta forma o país para um progresso de nível europeu. O estudo a que nos propomos, uma investigação documental no domínio da História da Ciência1, visa aprofundar os conhecimentos existentes sobre esta época e perceber o impacto da reforma do ECE, principalmente nos Liceus, caracterizando as principais figuras, políticas e docentes responsáveis pela sua conceptualização e aplicação. Através desta investigação procuraremos lançar as primeiras bases para descobrir as origens deste pensamento, querendo ainda comparar os fundamentos psicopedagógicos, epistemológicos e sociológicos da época com as principais ideias actualmente presentes no ensino da Ciência. Com este trabalho pretendemos, num primeiro momento, apresentar e divulgar o desenho da investigação e os seus objectivos, na procura de estabelecer parcerias e receber contributos da comunidade académica interessada por esta problemática
On the limits to mobility in InAs quantum wells with nearly lattice-matched barriers
The growth and the density dependence of the low temperature mobility of a
series of two-dimensional electron systems confined to un-intentionally doped,
low extended defect density InAs quantum wells with AlGaSb
barriers are reported. The electron mobility limiting scattering mechanisms
were determined by utilizing dual-gated devices to study the dependence of
mobility on carrier density and electric field independently. Analysis of the
possible scattering mechanisms indicate the mobility was limited primarily by
rough interfaces in narrow quantum wells and a combination of alloy disorder
and interface roughness in wide wells at high carrier density within the first
occupied electronic sub-band. At low carrier density the functional dependence
of the mobility on carrier density provided evidence of coulombic scattering
from charged defects. A gate-tuned electron mobility exceeding 750,000
cm/Vs was achieved at a sample temperature of 2 K.Comment: 23 pages, 7 figures, 1 tabl
RNA-Seq Differentiates Tumour and Host mRNA Expression Changes Induced by Treatment of Human Tumour Xenografts with the VEGFR Tyrosine Kinase Inhibitor Cediranib.
Pre-clinical models of tumour biology often rely on propagating human tumour cells in a mouse. In order to gain insight into the alignment of these models to human disease segments or investigate the effects of different therapeutics, approaches such as PCR or array based expression profiling are often employed despite suffering from biased transcript coverage, and a requirement for specialist experimental protocols to separate tumour and host signals. Here, we describe a computational strategy to profile transcript expression in both the tumour and host compartments of pre-clinical xenograft models from the same RNA sample using RNA-Seq. Key to this strategy is a species-specific mapping approach that removes the need for manipulation of the RNA population, customised sequencing protocols, or prior knowledge of the species component ratio. The method demonstrates comparable performance to species-specific RT-qPCR and a standard microarray platform, and allowed us to quantify gene expression changes in both the tumour and host tissue following treatment with cediranib, a potent vascular endothelial growth factor receptor tyrosine kinase inhibitor, including the reduction of multiple murine transcripts associated with endothelium or vessels, and an increase in genes associated with the inflammatory response in response to cediranib. In the human compartment, we observed a robust induction of hypoxia genes and a reduction in cell cycle associated transcripts. In conclusion, the study establishes that RNA-Seq can be applied to pre-clinical models to gain deeper understanding of model characteristics and compound mechanism of action, and to identify both tumour and host biomarkers
Neutrophils in cancer: neutral no more
Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets
Estimation of MSY on six species of commercially important demersal fishes in the Persian Gulf & Oman Sea (Hormuzgan province)
Today, calculation of MSY is one of the necessary fisheries management in control and prevention of the fish population reduction and is obtained with different methods. This study has focused on six species of commercial fish, including Tiger-toothed croaker, Javelin grunter, John`s snapper, Indian spiny turbot, Yellowfin seabream and Silver pomfret. The study was done monthly, from January 2007 to March 2008, in three fish landing regions including: Bandar Lengeh, Bandar Abbas and Qeshm Island (Slakh, Basydu and Chahoshrqy). Total 5163 Silver pomfret (Pompus argenteus), 1766 Javelin grunter (Pomadasys kaakan), 2151 John`s snapper (Lutjanus johnii), 3280 Tiger-toothed croaker (Otolithes ruber), 1628 Indian spiny turbot (Psettodes erumei) and the number of 759 Yellowfin seabream (Acnthopagrus latus) were assessed and length biometry has been done, monthly. In this study, two methods were used to determine the maximum sustainable yield (MSY): 1- virtual population analysis (Cohort analysis) 2- use of statistics and information that was estimated with two method, catch prediction and biomass (Standing stock). The results showed that in 2007, MSY value was estimated through catch prediction for Silver pomfret, Tigertoothed croaker, Javelin grunter, John`s snapper, Indian spiny turbot and Yellowfin seabream 1354, 1116, 1099.6, 1045.5, 914.5 and 529.5 tons, respectively. Moreover, this estimation have been done through standing stock for Silver pomfret, Tiger-toothed croaker, Javelin grunter, John`s snapper, Indian spiny turbot and Yellowfin seabream 1215, 633, 1304, 878, 1095 and 441 tons, respectively; and through VPA for Silver pomfret, Tiger-toothed croaker, Javelin grunter, John`s snapper, Indian spiny turbot and Yellowfin seabream 1100, 850, 920, 732.5, 1002.3 and 403 tons, respectively. Amount of biomass (Standing Stock) was estimated for Silver pomfret, Tiger-toothed croaker, Javelin grunter, John`s snapper, Indian spiny turbot and Yellowfin seabream 2530, 1172, 1738, 1689, 1470 and 1110 tons, respectively. In general, by assessing the obtained results for the studied species, except the fishing prediction results of the Javelin grunter and Tiger-toothed croaker species, which is less valuable due to the low correlation coefficient, it can be stated that except fishing pressure on John`s snapper and Tiger-toothed croaker, in other species studied, fishing conditions are in optimal situation
Angiostatin anti-angiogenesis requires IL-12: The innate immune system as a key target
© 2009 Albini et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
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Novel glycopolymer hydrogels as mucosa-mimetic materials to reduce animal testing
Glycopolymer hydrogels capable of mimicking mucosal tissue in mucoadhesion testing have been designed. Liquid formulations containing mucoadhesive polymers were found to be retained on these tissues to the same extent as ex vivo gastric mucosa, when using a dynamic method of assessing mucoadhesion
Planar Josephson Junctions Templated by Nanowire Shadowing
More and more materials, with a growing variety of properties, are built into
electronic devices. This is motivated both by increased device performance and
by the studies of materials themselves. An important type of device is a
Josephson junction based on the proximity effect between a quantum material and
a superconductor, useful for fundamental research as well as for quantum and
other technologies. When both junction contacts are placed on the same surface,
such as a two-dimensional material, the junction is called ``planar". One
outstanding challenge is that not all materials are amenable to the standard
planar junction fabrication. The device quality, rather than the intrinsic
characteristics, may be defining the results. Here, we introduce a technique in
which nanowires are placed on the surface and act as a shadow mask for the
superconductor. The advantages are that the smallest dimension is determined by
the nanowire diameter and does not require lithography, and that the junction
is not exposed to chemicals such as etchants. We demonstrate this method with
an InAs quantum well, using two superconductors - Al and Sn, and two
semiconductor nanowires - InAs and InSb. The junctions exhibit critical current
levels consistent with transparent interfaces and uniform width. We show that
the template nanowire can be operated as a self-aligned electrostatic gate.
Beyond single junctions, we create SQUIDs with two gate-tunable junctions. We
suggest that our method can be used for a large variety of quantum materials
including van der Waals layers, topological insulators, Weyl semimetals and
future materials for which proximity effect devices is a promising research
avenue.Comment: Written using The Block Method. Data on Zenodo DOI:
https://doi.org/10.5281/zenodo.641608
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