95 research outputs found

    The ‘mosaic habitat’ concept in human evolution: past and present

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    The habitats preferred by hominins and other species are an important theme in palaeoanthropology, and the ‘mosaic habitat’ (also referred to as habitat heterogeneity) has been a central concept in this regard for the last four decades. Here we explore the development of this concept – loosely defined as a range of different habitat types, such as woodlands, riverine forest and savannah within a limited spatial area– in studies of human evolution in the last sixty years or so. We outline the key developments that took place before and around the time when the term ‘mosaic’ came to wider palaeoanthropological attention. To achieve this we used an analysis of the published literature, a study of illustrations of hominin evolution from 1925 onwards and an email survey of senior researchers in palaeoanthropology and related fields. We found that the term mosaic starts to be applied in palaeoanthropological thinking during the 1970’s due to the work of a number of researchers, including Karl Butzer and Glynn Isaac , with the earliest usage we have found of ‘mosaic’ in specific reference to hominin habitats being by Adriaan Kortlandt (1972). While we observe a steady increase in the numbers of publications reporting mosaic palaeohabitats, in keeping with the growing interest and specialisation in various methods of palaeoenvironmental reconstruction, we also note that there is a lack of critical studies that define this habitat, or examine the temporal and spatial scales associated with it. The general consensus within the field is that the concept now requires more detailed definition and study to evaluate its role in human evolution

    An Observational Overview of Solar Flares

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    We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era. Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections. We also discuss flare soft X-ray spectroscopy and the energetics of the process. The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory. The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations.Comment: This is an article for a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

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    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

    Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

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    A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

    Centrality Dependence Of The Pseudorapidity Density Distribution For Charged Particles In Pb-pb Collisions At √snn=2.76tev

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    7264/Mai61062

    Post-typhoon prevalence of post-traumatic stress disorder, major depressive disorder, panic disorder, and generalized anxiety disorder in a Vietnamese sample

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    In 2006, typhoon Xangsane disrupted a multiagency health needs study of 4,982 individuals in Vietnam. Following this disaster, 798 of the original participants were reinterviewed to determine prevalence and risk factors associated with posttraumatic stress disorder (PTSD), major depressive disorder (MDD), panic disorder (PD), and generalized anxiety disorder (GAD). Posttyphoon prevalences were PTSD 2.6%, MDD 5.9%, PD 9.3%, and GAD 2.2%. Of those meeting criteria for a disorder, 70% reported only one disorder, 15% had two, 14% had three, and 1% met criteria for all four disorders. Risk factors for posttyphoon psychopathology differed among disorders, but generally were related to high typhoon exposure, prior trauma exposure, and in contrast to Western populations, higher age, but not gender

    Direct Optimal Control and Model Predictive Control

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    Model predictive control is a feedback control technique based on repeatedly solving optimal control problems. Direct methods for optimal control have gained popularity especially for practical applications, due to their flexibility. In this chapter we first present the state of the art in MPC stability theory. Then, we introduce the numerical methods used for direct optimal control and some variants specifically tailored to MPC. We conclude the chapter with five application examples. © Springer International Publishing AG 2017

    Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall

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    This paper reports the impact on confinement and power load of the high-shape 2.5MA ELMy H-mode scenario at JET of a change from an all carbon plasma facing components to an all metal wall. In preparation to this change, systematic studies of power load reduction and impact on confinement as a result of fuelling in combination with nitrogen seeding were carried out in JET-C and are compared to their counterpart in JET with a metallic wall. An unexpected and significant change is reported on the decrease of the pedestal confinement but is partially recovered with the injection of nitrogen.Comment: 30 pages, 16 figure

    Arquitetura, anatomia e histoquímica das folhas de Gomphrena arborescens L.f. (Amaranthaceae) Architecture, anatomy and histochemistry of the leaves of Gomphrena arborescens L.f. (Amaranthaceae)

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    As folhas de Gomphrena arborescens L.f., nativa do Cerrado, são utilizadas contra dismenorréia na medicina popular. As investigações morfológica, anatômica e histoquímica das folhas visam fornecer elementos para taxonomia, para controle de qualidade de drogas e identificação microscópica de fitoterápicos. Folhas foram coletadas em Brasília, DF, nas áreas de Cerrado do Centro Olímpico da Univesidade de Brasília e na Reserva Ecológica do IBGE. Foram efetuadas análises morfológicas, anatômicas e histoquímicas. Os estudos de arquitetura foliar, densidade estomática e de vênulas terminais foram efetuados em folhas diafanizadas, apresentando médias de 42,39&plusmn;15,50 estômatos mm-2 e 11,7&plusmn;3,55 vênulas terminais mm². As folhas apresentaram duas formas de tricomas tectores. O mesofilo bilateral apresenta tecido clorenquimático disposto radialmente à bainha parenquimática completa que envolve os feixes vasculares, características da síndrome Kranz associada ao ciclo fotossintético C4. O amido concentra-se na bainha parenquimática. As folhas são ricas em celulose, drusas de oxalato de cálcio, proteínas, lignina e outros compostos fenólicos, entre eles os flavonóides. As folhas apresentam morfologia variável, mas o padrão anatômico e de venação são constantes.<br>Leaves of the Brazilian Cerrado plant Gomphrena arborescens L.f. are used against dismenorea in popular medicine. The morphological, anatomical and histochemical investigation aims to help taxonomy, quality control of drugs and microscopical identification of phytotherapics. The leaves have been collected in Brasília, DF, in the Olympical Center of the University of Brasilia and in the Ecological Reserve of IBGE. The leaf architecture, stomatal and veinlet densities have been studied in clarified leaves, presenting average of 42,39&plusmn;15,50 stomata mm² and 11,7&plusmn;3,55 veinlet mm-2. Leaves presented two forms of tector trichomes. The bilateral mesophyll surrounds the complete bundle sheat, features of the Kranz syndrome associated with C4 photosynthetic pathway. The starch is concentrated in the bundle sheat cells. Leaves are rich in cellulose, calcium oxalate druses, proteins, lignin and other phenolic compounds, such as flavonoids. Leaves present variable morphology, but steady pattern of anatomy and veination
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