1,713 research outputs found

    Laser-Nucleus Interactions: The Quasiadiabatic Regime

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    The interaction between nuclei and a strong zeptosecond laser pulse with coherent MeV photons is investigated theoretically. We provide a first semi-quantitative study of the quasiadiabatic regime where the photon absorption rate is comparable to the nuclear equilibration rate. In that regime, multiple photon absorption leads to the formation of a compound nucleus in the so-far unexplored regime of excitation energies several hundred MeV above the yrast line. The temporal dynamics of the process is investigated by means of a set of master equations that account for dipole absorption, stimulated dipole emission, neutron decay and induced fission in a chain of nuclei. That set is solved numerically by means of state-of-the-art matrix exponential methods also used in nuclear fuel burnup and radioactivity transport calculations. Our quantitative estimates predict the excitation path and range of nuclei reached by neutron decay and provide relevant information for the layout of future experiments.Comment: 14 pages, 9 figures; v2 minor modifications in text, results unchange

    Evolución del género Megacricetodon del Aragoniense y Vallesiense (Mioceno) de la Península Ibérica

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    Tesis inédita presentada la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, leída el 11-03-2015Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEunpu

    Early Miocene evolution of the rodent Megacricetodon in Europe and its palaeobiogeographical implications

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    Received 20 June 2014, accepted 15 September 2014, available online 23 October 2014The Megacricetodon material from Aliveri (Isle of Evia, Greece) was previously assigned to M. primitivus, implying palaeobiogeographical relationship between south-eastern and south-western Europe. The material from Aliveri is here assigned to the new species Megacricetodon hellenicus sp. nov. This form has significant morphological differences compared to other Early Miocene species from Europe. This new evolutionary hypothesis of this genus has implications on the Early Miocene paleobiogeography of Europe. This work presents a new interpretation on the earliest European representative of the genus Megacricetodon from Aliveri localities. Analyses of the Megacricetodon material from MN 4 and MN 5 localities enable to propose a new palaeobiogeographical framework in which there are three main migration events of the genus Megacricetodon into Europe, each corresponding to different lineages that evolved independently. The new Greek taxon is considered the first migration wave from Anatolia, representing an endemic lineage different from any other European Megacricetodon.This research was supported by the Spanish MINECO Project No. GL-2008-04200/BTE and CGL2011-28877Peer reviewe

    Large-sized species of ctenodactylidae from the Valley of Lakes (Mongolia): An update on dental morphology, biostratigraphy, and paleobiogeography

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    Our study of the large and medium-sized species of Yindirtemys from the Valley of Lakes in Mongolia yielded three species: Yindirtemys deflexus, Y. suni and Y. birgeri. They differ in size and dental morphology. Yindirtemys suni is the largest and Y. birgeri the smallest species. Yindirtemys deflexus and Y. suni increase in body size but do not change dental morphology within their time range. The medium-sized Yindirtemys birgeri co-occurs in Mongolia with Y. deflexus in the late Oligocene (biozone C1) and is the easternmost occurrence of the species so far. Hitherto, Y. birgeri has been recorded from the Aral region in Kazakhstan only. Both Yindirtemys deflexus and Y. suni are used as biostratigraphic markers. Yindirtemys deflexus is a “key fossil” of the Chinese Land Mammal Age Tabenbulukian and for the Mongolian biozone C1; the latter correlates with the Oligocene. Yindirtemys suni is one of the “key fossils” of the Chinese Land Mammal Age Xiejian. In Mongolia the species ranges from the OligoceneMiocene transition (biozone C1-D) to the earliest Miocene (biozone D). The wide geographic range of Yindirtemys in the Oligocene of Asia suggests that no major physical barriers hampered mammal distribution between Kazakhstan, Mongolia and northern China, but local paleoecological and climatic conditions might have influenced mammal community structures in these areas.Peer Reviewe

    Reprogramming embedded systems at run-time

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    The dynamic re-programming of embedded systems is a long-standing problem in the field. With the advent of wireless sensor networks and the 'Internet of Things' it has now become necessary to be able to reprogram at run-time due to the difficulty of gaining access to such systems once deployed. The issues of power consumption, flexibility, and operating system protections are examined for a range of approaches, and a critical comparison is given. A combination of approaches is recommended for the implementation of real-world systems and areas where further work is required are highlighted.Postprin

    Reprogramming Embedded Systems at Run-Time

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    A new hybrid evolutionary algorithm for the treatment of equality constrained MOPs

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    Multi-objective evolutionary algorithms are widely used by researchers and practitioners to solve multi-objective optimization problems (MOPs), since they require minimal assumptions and are capable of computing a finite size approximation of the entire solution set in one run of the algorithm. So far, however, the adequate treatment of equality constraints has played a minor role. Equality constraints are particular since they typically reduce the dimension of the search space, which causes problems for stochastic search algorithms such as evolutionary strategies. In this paper, we show that multi-objective evolutionary algorithms hybridized with continuation-like techniques lead to fast and reliable numerical solvers. For this, we first propose three new problems with different characteristics that are indeed hard to solve by evolutionary algorithms. Next, we develop a variant of NSGA-II with a continuation method. We present numerical results on several equality-constrained MOPs to show that the resulting method is highly competitive to state-of-the-art evolutionary algorithms.Peer ReviewedPostprint (published version

    Acid base disorders in hospitalized cattle

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    Os objetivos deste estudo retrospectivo foram determinar os principais distúrbios ácido-base e eletrolíticos em bovinos internados, utilizando a abordagem Henderson-Hasselbalch e a abordagem físico-química comparando a utilidade diagnóstica e terapêutica de tais procedimentos. Foram revisados 31 prontuários de bovinos admitidos no Hospital de Animais de Grande Porte da Universidad Nacional de Colombia, que preencheram os critérios de inclusão da medição de gases sanguíneos, eletrólitos sanguíneos e proteínas plasmáticas na admissão antes de fornecer qualquer tratamento. Com o emprego da abordagem de Henderson-Hasselbalch, as anormalidades da base ácida foram encontradas em 83,3% dos pacientes, enquanto com a abordagem físico-química o valor obtido foi de 93,5%. Os principais distúrbios ácido-base encontrados foram forte acidose iônica (61,29%) e acidose ácida fraca (38,7%). A acidose com Ion Gap Forte (SIG) foi encontrada em 73,68% dos casos com forte acidose iônica. Estes resultados destacam a importância do diagnóstico de distúrbios ácido-base em bovinos doentes para o reconhecimento adequado dos fenômenos fisiopatológicos e sua compreensão para orientar as decisões de tratamento.The objectives of this retrospective study were to determine the main acid-base and electrolytes disorders in hospitalized cattle, using both Henderson-Hasselbalch and the physicochemical approach and to compare their diagnostic and therapeutic utility. A total of 31 medical records were reviewed of bovines admitted to the Large Animal Hospital at Universidad Nacional de Colombia, that met the inclusion criteria of the measurement of blood gases, blood electrolytes and plasma protein on admission before providing any treatment. Using the Henderson-Hasselbalch approach, acid base abnormalities were found in 83.3% of the patients, compared to 93.5% using the physicochemical approach. The principal acid-base disorders found were strong ion acidosis (61.29%) and weak acid acidosis (38.7%); strong ion gap (SIG) acidosis was found in 73.68% of cases showing strong ion acidosis. These results highlight the importance of the diagnosis of acid-base disorders in sick cattle for proper recognition of pathophysiological phenomena and its understanding to guide treatment decisions

    Humedad del suelo en el crecimiento y contenido de capsaicina en frutos de Capsicum spp.

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    "El chile (Capsicum spp.) fue uno de los primeros cultivos domesticados en Mesoamérica, México es el país con la mayor diversidad genética de Capsicum. La planta sintetiza y acumula capsaicinoides, un grupo de alcaloides responsables del picor, ubicados principalmente en el tejido de la placenta adyacente a las semillas, los niveles de éstos dependen de muchos factores, entre ellos, las deficiencias hídricas. El objetivo de este trabajo fue determinar el efecto de tres niveles de humedad en el suelo sobre el crecimiento y contenido de capsaicina en frutos de tres genotipos de chile. Se estableció bajo el diseño de bloques completos al azar con tres repeticiones en condiciones de invernadero"
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