342 research outputs found

    Teacher performance evaluation: conflict, uncertainties and the search for meaning(s)

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    O texto que propomos parte de uma pesquisa longitudinal, realizada em Portugal entre 2008 e 2010, com professores do 1º Ciclo do Ensino Básico. Procura evidenciar os conflitos e incertezas que a avaliação do desempenho docente tem produzido e a busca de sentido(s) para esta avaliação e para o ‘ser professor/a’. A implementação de sistemas de avaliação do desempenho dos professores insere-se na procura de soluções para esta inquietação. Foi o que aconteceu em Portugal, em Janeiro de 2007, com a publicação em Diário da República do novo Estatuto da Carreira Docente e o Decreto que regulamentava a Avaliação do Desempenho Docente. As tensões emergiram entre docentes e Ministério da Educação, agudizaram-se com a tomada de consciência da problemática da avaliação do desempenho dos docentes com impacto na carreira profissional e provocaram incertezas e desmotivação face ao sentido do trabalho docente com impacto na identidade profissional dos professores.This article stems from a longitudinal research carried out with primary school teachers in Portugal between 2008 and 2010. The research sought to identify the conflicts and uncertainties, which have been caused by the evaluation of teacher performance, as well as to search for meaning(s) related to that evaluation and to ‘being a teacher’. The implementation of systems for the evaluation of teacher performance fits into the search for solutions to that concern. This is what happened in Portugal, in January 2007, when the new Statute of the Teaching Profession and the law to regulate Teacher Performance Assessment were published in Diário da República – the official government publication. Tensions arose between teachers and the Ministry of Education and they were aggravated by an awareness of how the problem of teacher performance evaluation would impact on the professional career of teachers and how it would cause uncertainties and demotivation concerning the vocation of teaching and its subsequent impact on the professional identity of teachers

    An extensive database of airborne trace gas and meteorological observations from the Alpha Jet Atmospheric eXperiment (AJAX)

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    The Alpha Jet Atmospheric eXperiment (AJAX) flew scientific flights between 2011 and 2018 providing measurements of trace gas species and meteorological parameters over California and Nevada, USA. This paper describes the observations made by the AJAX program over 229 flights and approximately 450 h of flying. AJAX was a multi-year, multi-objective, multi-instrument program with a variety of sampling strategies resulting in an extensive dataset of interest to a wide variety of users. Some of the more common flight objectives include satellite calibration/validation (GOSAT, OCO-2, TROPOMI) at Railroad Valley and other locations and long-term observations of free-tropospheric and boundary layer ozone allowing for studies of stratosphere-to-troposphere transport and long-range transport to the western United States. AJAX also performed topical studies such as sampling wildfire emissions, urban outflow and atmospheric rivers. Airborne measurements of carbon dioxide, methane, ozone, formaldehyde, water vapor, temperature, pressure and 3-D winds made by the AJAX program have been published at NASA's Airborne Science Data Center (https://asdc.larc.nasa.gov/project/AJAXTS9 (last access: 1 November 2022), https://doi.org/10.5067/ASDC/SUBORBITAL/AJAX/DATA001, Iraci et al., 2021a).</p

    Terrain trapped airflows and precipitation variability during an atmospheric river event

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    We examine thermodynamic and kinematic structures of terrain trapped airflows (TTAs) during an atmospheric river (AR) event impacting Northern California 10–11 March 2016 using Alpha Jet Atmospheric eXperiment (AJAX) aircraft data, in situ observations, and Weather and Research Forecasting (WRF) Model simulations. TTAs are identified by locally intensified low-level winds flowing parallel to the coastal ranges and having maxima over the near-coastal waters. Multiple mechanisms can produce TTAs, including terrain blocking and gap flows. The changes in winds can significantly alter the distribution, timing, and intensity of precipitation. We show here how different mechanisms producing TTAs evolve during this event and influence local precipitation variations. Three different periods are identified from the time-varying wind fields. During period 1 (P1), a TTA develops during synoptic-scale onshore flow that backs to southerly flow near the coast. This TTA occurs when the Froude number (Fr) is less than 1, suggesting low-level terrain blocking is the primary mechanism. During period 2 (P2), a Petaluma offshore gap flow develops, with flows turning parallel to the coast offshore and with Fr \u3e 1. Periods P1 and P2 are associated with slightly more coastal than mountain precipitation. In period 3 (P3), the gap flow initiated during P2 merges with a pre-cold-frontal low-level jet (LLJ) and enhanced precipitation shifts to higher mountain regions. Dynamical mixing also becomes more important as the TTA becomes confluent with the approaching LLJ. The different mechanisms producing TTAs and their effects on precipitation pose challenges to observational and modeling systems needed to improve forecasts and early warnings of AR events

    Vertical Transport, Entrainment, and Scavenging Processes Affecting Trace Gases in a Modeled and Observed SEAC⁴RS Case Study

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    The convectively driven transport of soluble trace gases from the lower to the upper troposphere can occur on timescales of less than an hour, and recent studies suggest that microphysical scavenging is the dominant removal process of tropospheric ozone precursors. We examine the processes responsible for vertical transport, entrainment, and scavenging of soluble ozone precursors (formaldehyde and peroxides) for midlatitude convective storms sampled on 2 September 2013 during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC⁴RS) study. Cloud‐resolving simulations using the Weather Research and Forecasting with Chemistry model combined with aircraft measurements were performed to understand the effect of entrainment, scavenging efficiency (SE), and ice physics processes on these trace gases. Analysis of the observations revealed that the SEs of formaldehyde (43–53%) and hydrogen peroxide (~80–90%) were consistent between SEAC⁴RS storms and the severe convection observed during the Deep Convective Clouds and Chemistry Experiment (DC3) campaign. However, methyl hydrogen peroxide SE was generally smaller in the SEAC⁴RS storms (4%–27%) compared to DC3 convection. Predicted ice retention factors exhibit different values for some species compared to DC3, and we attribute these differences to variations in net precipitation production. The analyses show that much larger production of precipitation between condensation and freezing levels for DC3 severe convection compared to smaller SEAC⁴RS storms is largely responsible for the lower amount of soluble gases transported to colder temperatures, reducing the amount of soluble gases which eventually interact with cloud ice particles

    Avoiding moving obstacles

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    To successfully move our hand to a target, we must consider how to get there without hitting surrounding objects. In a dynamic environment this involves being able to respond quickly when our relationship with surrounding objects changes. People adjust their hand movements with a latency of about 120 ms when the visually perceived position of their hand or of the target suddenly changes. It is not known whether people can react as quickly when the position of an obstacle changes. Here we show that quick responses of the hand to changes in obstacle position are possible, but that these responses are direct reactions to the motion in the surrounding. True adjustments to the changed position of the obstacle appeared at much longer latencies (about 200 ms). This is even so when the possible change is predictable. Apparently, our brain uses certain information exceptionally quickly for guiding our movements, at the expense of not always responding adequately. For reaching a target that changes position, one must at some time move in the same direction as the target did. For avoiding obstacles that change position, moving in the same direction as the obstacle is not always an adequate response, not only because it may be easier to avoid the obstacle by moving the other way, but also because one wants to hit the target after passing the obstacle. Perhaps subjects nevertheless quickly respond in the direction of motion because this helps avoid collisions when pressed for time. © 2008 Springer-Verlag

    Reassessment of the TM 1517 odonto-postcranial assemblage from Kromdraai B, South Africa, and the maturational pattern of Paranthropus robustus

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    Objectives The Pleistocene taxon Paranthropus robustus was established in 1938 following the discovery at Kromdraai B, South Africa, of the partial cranium TM 1517a and associated mandible TM 1517b. Shortly thereafter, a distal humerus (TM 1517g), a proximal ulna (TM 1517e), and a distal hallucial phalanx (TM 1517k) were collected nearby at the site, and were considered to be associated with the holotype. TM 1517a‐b represents an immature individual; however, no analysis of the potentially associated postcranial elements has investigated the presence of any endostructural remnant of recent epiphyseal closure. This study aims at tentatively detecting such traces in the three postcranial specimens from Kromdraai B. Materials and Methods By using μXCT techniques, we assessed the developmental stage of the TM 1517b's C‐M3 roots and investigated the inner structure of TM 1517g, TM 1517e, and TM 1517k. Results The M2 shows incompletely closed root apices and the M3 a half‐completed root formation stage. The distal humerus was likely completely fused, while the proximal ulna and the distal hallucial phalanx preserve endosteal traces of the diaphyseo‐epiphyseal fusion process. Discussion In the hominin fossil record, there are few unambiguously associated craniodental and postcranial remains sampling immature individuals, an essential condition for assessing the taxon‐specific maturational patterns. Our findings corroborate the original association of the craniodental and postcranial remains representing the P. robustus type specimen. As with other Plio‐Pleistocene hominins, the odonto‐postcranial maturational pattern of TM 1517 more closely fits an African great ape rather than the extant human pattern

    Suppression of apoptosis inhibitor c-FLIP selectively eliminates breast cancer stem cell activity in response to the anti-cancer agent, TRAIL

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    Introduction It is postulated that breast cancer stem cells (bCSCs) mediate disease recurrence and drive formation of distant metastases - the principal cause of mortality in breast cancer patients. Therapeutic targeting of bCSCs however, is hampered by their heterogeneity and resistance to existing therapeutics. In order to identify strategies to selectively remove bCSCs from breast cancers, irrespective of their clinical subtype, we sought an apoptosis mechanism that would target bCSCs yet would not kill normal cells. Suppression of the apoptosis inhibitor cellular FLICE-Like Inhibitory Protein (c-FLIP) partially sensitizes breast cancer cells to the anti-cancer agent Tumour Necrosis Factor-Related Apoptosis Inducing Ligand (TRAIL). Here we demonstrate in breast cancer cell lines that bCSCs are exquisitely sensitive to the de-repression of this pro-apoptotic pathway, resulting in a dramatic reduction in experimental metastases and the loss of bCSC self-renewal. Methods Suppression c-FLIP was performed by siRNA (FLIPi) in four breast cancer cell lines and by conditional gene-knockout in murine mammary glands. Sensitivity of these cells to TRAIL was determined by complementary cell apoptosis assays, including a novel heterotypic cell assay, while tumour-initiating potential of cancer stem cell subpopulations was determined by mammosphere cultures, aldefluor assay and in vivo transplantation. Results Genetic suppression of c-FLIP resulted in the partial sensitization of TRAIL-resistant cancer lines to the pro-apoptotic effects of TRAIL, irrespective of their cellular phenotype, yet normal mammary epithelial cells remained refractory to killing. While 10%-30% of the cancer cell populations remained viable after TRAIL/FLIPi treatment, subsequent mammosphere and aldefluor assays demonstrated that this pro-apoptotic stimulus selectively targeted the functional bCSC pool, eliminating stem cell renewal. This culminated in an 80% reduction in primary tumours and a 98% reduction in metastases following transplantation. The recurrence of residual tumour initiating capacity was consistent with the observation that post-treated adherent cultures re-acquired bCSC-like properties in vitro. Importantly however this recurrent bCSC activity was attenuated following repeated TRAIL/FLIPi treatment. Conclusions We describe an apoptotic mechanism that selectively and repeatedly removes bCSC activity from breast cancer cell lines and suggest that a combined TRAIL/FLIPi therapy could prevent metastatic disease progression in a broad range of breast cancer subtypes. [PROVISIONAL
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