211 resultados para 2K-Gießharz
Resumo:
The West Shandong Uplift and its adjacent basins, with same evolutional history before Mesozoic, are an important basin-orogenic systems in North China. After late Mesozoic, tectonic differentiation between basin and orogenic belt gradually displayed in the study area. The Boxing sag is a part of Jiyang Depression near to West Shandong Uplift, in which the whole Mesozoic and Cenozoic strata are preserved. Based on the analysis of sedimentary records in the Boxing sag, the Cenozoic structural and sedimentary evolutions in Boxing Sag and its response to Western Shandong uplift are discussed in this dissertation. The main conclusions in this research are presented as follows. Based on Seismic and well logging profile interpretation, fault growth index, thickness difference between bottom wall and top wall and fault activity rate from Eocene to Pliocene are studied. Boxing sag had three main faults, NE, NW and NEE trending faults. Research shows that the activity of the NW trending fault in the Boxing sag became weaken from E1-2S4 to N2m gradually. The evolution of NE and the NEE trending fault can be divided into three episodes, from E1-2k to E2s4, from E2s3 to E3s1, from N2m to E3d. The analysis of Paleogene samples of heavy mineral assemblages shows that metamorphic rocks represented by garnet, intermediate-acid igneous rocks represented by the assemblage of apatite, zircon and tourmaline became less from E1-2k to N2g, and sedimentary rocks represented by the assemblage of pyrite, barite and limonite also became less. Intermediate-basic igneous rocks represented by the assemblage of leucoxene, rutile and ilmenite and metamorphic rocks represented by epidote became more and more. Electronic microprobe analysis shows that glaucophane and barroisite are existed in Kongdian Formation and the 4th member of Shahejie Formation, and they demonstrate that Western Shandong and Eastern Shandong are all the source regions of the Boxing Sag, and they also indicate that oceanic crust existed before the collision between the Yangtze and North China continent. The fact that Eastern Shandong is the source region of Boxing Sag also indicates that Western Shandong was not high enough to prevent sediment from Eastern Shandong at E1-2k and E2s4. The results of the dating of five detrital zircons of Boxing Sag show Kongdian Formation and the 4th member of Shahejie Formation have the age peaks of 2800Ma and 700-800. It means that Eastern Shandong is the source region of Boxing Sag at early Paleogene and Western Shandong is not high enough to prevent the sediment from Eastern Shandong. The ages of 160-180 and 220-260 Ma, which exist in the Guantao Formation and Paleogene, are common in Eastern Shandong and rare in Western Shandong,and it implied that Western Shandong is a low uplift at 24Ma. The Paleogene strata have almost same age groups, while the Guantao Formation has significant variations of age groups, and this indicates that Boxing Sag and Western Shandong uplift had taken place tremendous changes. The results of apatite fission track in Boxing sag show that three times uplifts happened at the source region at 60 Ma, 45Ma and 15Ma respectively, and the Boxing sag experienced two subsidences at 60Ma, 45Ma and one uplift at 20Ma.
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利用被动微波遥感亮度温度数据反演月壤厚度是“嫦娥”探月工程的科学目标之一,也是人类探测月壤厚度的一种新的尝试。深入研究月表太阳辐射、月球内部热流以及月表温度的分布和变化规律,是解译遥感数据,反演月壤厚度的前提条件,也为进一步开展月球探测、开发利用月球资源乃至建立月球基地相关研究工作提供必要的参考。 本文根据月表有效太阳辐照度与太阳常数、日月距离和太阳辐射入射角的关系,建立了月表有效太阳辐照度的实时模型如下: (1) 其中, (2) (3) 通过对月表有效太阳辐照度实时模型的各个参数分析发现,影响月表有效太阳辐照度变化的主要因素是日地距离和太阳辐射入射角的变化。对模型的误差分析表明,从1950年到2050年的100年内,月表有效太阳辐照度计算结果的误差百分比小于0.28%,能更准确地反映月表有效太阳辐照度的变化情况。从2007年月表有效太阳辐照度的计算结果发现,该年内的月表有效太阳辐照度变化在1321.5~1416.6 W•m-2之间,平均为1368.0 W•m-2,一个月内的变化最小幅度为6.0 W•m-2,最大幅度为23.6 W•m-2。 在月表有效太阳辐照度的实时模型基础上,根据能量守恒和Stefan-Boltzmann定律,本文还得出了月表温度分布模型如下: (4) 其中,初始条件由下式决定, (5) 通过与月表温度实际观测结果的比较发现,当月表反射率、热发射率和热惯量分别取0.127、0.94和125 J•m-2•s-1/2•K-1时,模型的计算结果与实际观测值比较符合,能较好地预测理想条件下的月表温度。 月表热参数研究的一个重要应用就是解译对月被动微波遥感的亮度温度数据。在对月被动微波遥感探测中,辐射计获得的亮度温度反映了月球表层的热辐射特性。月球表层的热辐射与其自身的热状况紧密相关,结合文中建立的月表热参数模型,根据辐射传播理论进一步分析了对月微波遥感探测中,月球表层在不同情况下对亮度温度的贡献,确定了亮度温度随月表温度和月壤厚度的变化关系,对被动微波遥感探测月壤厚度的可能性和可能达到的精度进行了估算。 对月球表层的热辐射传播的分析发现,对月被动微波遥感探测获得的亮度温度受月球表层热辐射的控制,与月壤厚度具有指数相关性,并受到月表温度的影响。当月壤和月岩的复介电常数分别为2 + 0.005 j和9 + 1 j、相对磁导率均为1时,对应3.0GHz、7.8GHz、19.35GHz和37.0GHz四个频率的亮度温度与月壤厚度及月表温度的关系可分别近似表示为, 3.0GHz亮度温度: (6) 7.8GHz亮度温度: (7) 19.35GHz亮度温度: (8) 37.0GHz亮度温度: (9) 当月壤厚度和月表温度分别在0.5m~30m和100K~400K之间变化时,上述四个频率的亮度温度变化范围分别在212.5K~252.8K、207.4 K~266.7K、193.8 K~288.6K和174.0 K~310.9K之间。对于较低频率的被动微波遥感,亮度温度随月壤厚度的增大逐渐增大并趋于稳定;对较高频率的被动微波遥感,亮度温度随月壤厚度的增大会产生起伏波动,不利于用单波段反演月壤厚度。亮度温度梯度在频率较高时梯度较大,在很小的月壤厚度范围内很快就趋于0,不利于厚度较大时的月壤厚度反演,但对于厚度较小时的月壤厚度反演精度较高;同时,除3.0GHz外,7.8GHz、19.35GHz和37.0GHz三个频率的亮度温度梯度随月表温度的升高降幅较大,尤其是19.35GHz,适合在夜间对月壤厚度较小的地区进行更精确的探测。对于3.0GHz,其亮度温度梯度受月表温度变化的影响很小,能反映出较深层月壤厚度的信息,可以对月球进行全球全天时探测。若辐射计的分辨率为0.02K,3.0GHz频率对10m厚月壤的判别精度达到0.07m;对于20m厚月壤的精度为1.4m。当月壤厚度小于0.5m时,随着月壤厚度从0到0.5m增加,月球表层的亮度温度贡献呈先减小后增大的趋势,从而使某一亮度温度值可能对应存在两种不同的月壤厚度。因此,对于月壤厚度小于0.5m的区域,利用单波段被动微波遥感亮度温度反演月壤厚度是比较困难的。 在对月被动微波遥感探测中,可以利用月球夜晚时段的亮度温度数据判别月壤厚度是否小于0.5m。当月表温度为100K时,3.0GHz、7.8GHz、19.35GHz和37.0GHz四个频率的亮度温度判别参考值分别为212.9K、207.4K、193.5K和174.1K;月表温度为240K时,上述四个频率的亮度温度判别参考值分别为220.8K、226.8K、234.1K和237.2K。当亮度温度小于参考值时表示月壤厚度小于0.5m,反之,表示月壤厚度大于0.5m。更进一步地,可以根据月表温度的影响系数对月岩是否裸露于月表进行判断。当3.0GHz、7.8GHz、19.35GHz和37.0GHz四个频率的月表温度影响系数接近0.77、0.82、0.84和0.85时,可以认为月岩直接暴露于月表。
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Langerin is a C-type lectin expressed by a subset of dendritic leukocytes, the Langerhans cells (LC). Langerin is a cell surface receptor that induces the formation of an LC-specific organelle, the Birbeck granule (BG). We generated a langerin(-/-) mouse on a C57BL/6 background which did not display any macroscopic aberrant development. In the absence of langerin, LC were detected in normal numbers in the epidermis but the cells lacked BG. LC of langerin(-/-) mice did not present other phenotypic alterations compared to wild-type littermates. Functionally, the langerin(-/-) LC were able to capture antigen, to migrate towards skin draining lymph nodes, and to undergo phenotypic maturation. In addition, langerin(-/-) mice were not impaired in their capacity to process native OVA protein for I-A(b)-restricted presentation to CD4(+) T lymphocytes or for H-2K(b)-restricted cross-presentation to CD8(+) T lymphocytes. langerin(-/-) mice inoculated with mannosylated or skin-tropic microorganisms did not display an altered pathogen susceptibility. Finally, chemical mutagenesis resulted in a similar rate of skin tumor development in langerin(-/-) and wild-type mice. Overall, our data indicate that langerin and BG are dispensable for a number of LC functions. The langerin(-/-) C57BL/6 mouse should be a valuable model for further functional exploration of langerin and the role of BG.
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Context. It has been established that the classical gas-phase production of interstellar methanol (CH3OH) cannot explain observed abundances. Instead it is now generally thought that the main formation path has to be by successive hydrogenation of solid CO on interstellar grain surfaces. Aims. While theoretical models and laboratory experiments show that methanol is efficiently formed from CO on cold grains, our aim is to test this scenario by astronomical observations of gas associated with young stellar objects (YSOs). Methods. We have observed the rotational transition quartets J = 2K – 1K of 12CH3OH and 13CH3OH at 96.7 and 94.4 GHz, respectively, towards a sample of massive YSOs in different stages of evolution. In addition, the J = 1-0 transitions of 12C18O and 13C18O were observed towards some of these sources. We use the 12C/13C ratio to discriminate between gas-phase and grain surface origin: If methanol is formed from CO on grains, the ratios should be similar in CH3OH and CO. If not, the ratio should be higher in CH3OH due to 13C fractionation in cold CO gas. We also estimate the abundance ratios between the nuclear spin types of methanol (E and A). If methanol is formed on grains, this ratio is likely to have been thermalized at the low physical temperature of the grain, and therefore show a relative over-abundance of A-methanol. Results. We show that the 12C/13C isotopic ratio is very similar in gas-phase CH3OH and C18O, on the spatial scale of about 40 arcsec, towards four YSOs. For two of our sources we find an overabundance of A-methanol as compared to E-methanol, corresponding to nuclear spin temperatures of 10 and 16 K. For the remaining five sources, the methanol E/A ratio is less than unity. Conclusions. While the 12C/13C ratio test is consistent with methanol formation from hydrogenation of CO on grain surfaces, the result of the E/A ratio test is inconclusive.
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We study an energy-constrained sandpile model with random neighbors. The critical behavior of the model is in the same universality class as the mean-field self-organized criticality sandpile. The critical energy E-c depends on the number of neighbors n for each site, but the various exponents are independent of n. A self-similar structure with n-1 major peaks is developed for the energy distribution p(E) when the system approaches its stationary state. The avalanche dynamics contributes to the major peaks appearing at E-Pk = 2k/(2n - 1) with k = 1,2,...,n-1, while the fine self-similar structure is a natural result of the way the system is disturbed. [S1063-651X(99)10307-6].
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A series of alkyl aryl sulfides were metabolised, using selected strains of the soil bacterium Pseudomonas putida containing either toluene dioxygenase (TDO) or naphthalene dioxygenase (NDO), to give chiral sulfoxides. Alkyl aryl sulfoxides 2a-2k, 4a-4j and 4l, having enantiomeric excess (ee) values of >90%, were obtained by use of the appropriate strain of P. putida (UV4 or NCIMB 8859), Enantiocomplimentarity was observed for the formation of sulfoxides 2a, 2b, 2d, 2j, 4a, 4b and 4d, with TDO-catalysed (UV4) oxidation favouring the (R) enantiomer and NDO-catalysed oxidation (NCIMB 8859) the (S) enantiomer. Evidence of involvement of the TDO enzyme was obtained using a recombinant strain of Escherichia coli (pKST 11), The marked degree of stereoselectivity appears to be mainly due to enzyme-catalysed asymmetric sulfoxidation, however the possibility of a minor contribution from kinetic resolution, in some cases, cannot be excluded.
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A indução da doença do transplante contra o hospedeiro (GVHD) depende da activação das células dadoras T pelas células do hospedeiro que apresentamantigenio (APCs). A teoria prevalecente descreve que estas interacções ocorrem nos órgãos linfáticos secundários (SLO), tais como os nóduloslinfáticos (LN), as placas de Peyer’s (PP) e o baço (SP). Esta hipótese foi testada usando ratinhos homozigóticos aly/aly (alinfoplasia) que não têm LN nem PP, usando como controlo os ratinhos heterozigóticos (aly/+) da mesma ninhada. Os dois grupos foram irradiados com dose letal após a remoção do baço aos ratinhos aly/aly (LN/PP/SP-/-), enquanto nos ratinhos aly/+ o baço foi deslocado e recolocado. Ambos receberam transplante de medula óssea (BMT) de ratinhos dadores singénicos (aly/aly, H-2b) ou de ratinhos alogénicos, com diferente complexo principal de histocompatibilidade (MHC) (BALB/c, H-2dou B10.BR, H-2k). A severidade de GVHD foi medida pela sobrevivência,e pelo sistema de pontuação, bem estabelecido, quer de doença clínica quer de doença dos órgãos alvo. Surpreendentemente, todos os ratinhos LN/PP/SP-/-sobreviveram, desenvolvendo GVHD clinicamente significativo, comparável,em severidade, com o observado nos ratinhos LN/PP/SP+/+. Além disso, asanálises histopatológicas demonstraram que os ratinhos LN/PP/SP-/-receptores de BMTdesenvolveram significativamente mais GVHD no fígado,no intestino, e na pele quando comparados com os animais singénicos decontrolo. Os ratinhos LN/PP/SP-/-desenvolveram também GVHD hepático mais severo quando comparados com os ratinhos de controlo LN/PP/SP+/+. Diferenças semelhantes foram ainda observadas, logo ao 7º dia, para o GVHDhepático entre os grupos alogénicos. Para identificar quais os órgãos extra-linfáticos do receptor que poderão servir como sítios iniciais de exposição a antigenios alogénicos, na ausência de SLO, foi examinada a expansão das células T (CD3+), a sua activação (CD69+), e a sua proliferação (CFSE) na medula óssea, 3 dias depois do BMT. Em cada caso, os ratinhos LN/PP/SP-/-transplantados com medula de dadores alogénicos apresentaram númerosabsolutos significativamente maiores quer de células, quer de divisõescelulares, se comparados com os LN/PP/SP+/+. Para garantir que as diferenças experimentais observadas nos animais aly/aly, no sistema díspar do MHC, não são apenas um fenómeno dependente da estirpe de ratinho, foramtransplantados ratinhos sem baço FucT dko (LN/PP/SP-/-), previamente tratados com o anticorpo monoclonal (mAb) anti-MadCAM-1. Após o BMT estes ratinhos apresentaram elevada pontuação clínica de GVHD, mostrando que os SLO não são necessários para a indução de GVHD. Em estudos de transplante-versus-leucemia usando hospedeiros homozigóticos (LN/PP/SP-/-) estes ratinhos morreram devido a expansão tumoral e não devido a GVHD.Estudos in vitro mostraram que a capacidade das APCs, quer das célulasdendríticas (DCs) esplénicas, quer das DCs derivadas da medula óssea, dosratinhos aly/aly e aly/+ eramcomparável. Colectivamente, estes resultados são consistentes com a noção de que os SLO não são necessários para a activação alogénica das celulas T, sugerindo que a medula óssea pode ser umlocal alternativo, embora menos eficiente, para o reconhecimento alogénico deantígenos e consequente activação das células dadoras T. Estas observações desafiam o paradigma de que os tecidos linfáticos secundários sãonecessários para a indução de GVHD.
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Purple bronze Li0.9Mo6O17 has attracted researchers for its low dimensionality and corresponding properties. Although it has been studied for nearly two decades, there are still some unsolved puzzles with this unique material. Single crystals of Li0.9Mo6O17 were grown using the temperature gradient flux technique in this research. The crystal growth was optimized by experimenting different conditions and good quality crystals were obtained. X-ray diffraction results have confirmed the right phase of the crystals. Resistivity measurements and magnetic susceptibility measurements were carried out, and anomalous electronic behaviors were found. All of the samples showed the metal-insulator transition near 20K, followed by behavior that differs from sample to sample: either superconducting, metallic or insulating behavior was observed below 2K. Li0.9Mo6O17 was considered as a quasi-one-dimensional crystal and also a superconducting crystal, which implies a dimensional crossover may occur at the metal-insulator transition. A two-band scenario of the Luttinger liquid model was used to fit the resistivity data and excellent results were achieved, suggesting that the Luttinger theory is a very good candidate for the explanation of the anomalous behavior of Li0.9Mo6O17. In addition, the susceptibility measurements showed Curie paramagnetism and some temperature independent paramagnetism at low temperature. The absence of any anomalous magnetic feature near 20K where the resistivity upturn takes place, suggests that a charge density wave mechanism, which has been proposed by some researchers, is not responsible for the unique properties of Li0.9Mo6O17.
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Dans cette thèse, nous proposons de nouveaux résultats de systèmes superintégrables séparables en coordonnées polaires. Dans un premier temps, nous présentons une classification complète de tous les systèmes superintégrables séparables en coordonnées polaires qui admettent une intégrale du mouvement d'ordre trois. Des potentiels s'exprimant en terme de la sixième transcendante de Painlevé et de la fonction elliptique de Weierstrass sont présentés. Ensuite, nous introduisons une famille infinie de systèmes classiques et quantiques intégrables et exactement résolubles en coordonnées polaires. Cette famille s'exprime en terme d'un paramètre k. Le spectre d'énergie et les fonctions d'onde des systèmes quantiques sont présentés. Une conjecture postulant la superintégrabilité de ces systèmes est formulée et est vérifiée pour k=1,2,3,4. L'ordre des intégrales du mouvement proposées est 2k où k ∈ ℕ. La structure algébrique de la famille de systèmes quantiques est formulée en terme d'une algèbre cachée où le nombre de générateurs dépend du paramètre k. Une généralisation quasi-exactement résoluble et intégrable de la famille de potentiels est proposée. Finalement, les trajectoires classiques de la famille de systèmes sont calculées pour tous les cas rationnels k ∈ ℚ. Celles-ci s'expriment en terme des polynômes de Chebyshev. Les courbes associées aux trajectoires sont présentées pour les premiers cas k=1, 2, 3, 4, 1/2, 1/3 et 3/2 et les trajectoires bornées sont fermées et périodiques dans l'espace des phases. Ainsi, les résultats obtenus viennent renforcer la possible véracité de la conjecture.
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Gowers, dans son article sur les matrices quasi-aléatoires, étudie la question, posée par Babai et Sos, de l'existence d'une constante $c>0$ telle que tout groupe fini possède un sous-ensemble sans produit de taille supérieure ou égale a $c|G|$. En prouvant que, pour tout nombre premier $p$ assez grand, le groupe $PSL_2(\mathbb{F}_p)$ (d'ordre noté $n$) ne posséde aucun sous-ensemble sans produit de taille $c n^{8/9}$, il y répond par la négative. Nous allons considérer le probléme dans le cas des groupes compacts finis, et plus particuliérement des groupes profinis $SL_k(\mathbb{Z}_p)$ et $Sp_{2k}(\mathbb{Z}_p)$. La premiére partie de cette thése est dédiée à l'obtention de bornes inférieures et supérieures exponentielles pour la mesure suprémale des ensembles sans produit. La preuve nécessite d'établir préalablement une borne inférieure sur la dimension des représentations non-triviales des groupes finis $SL_k(\mathbb{Z}/(p^n\mathbb{Z}))$ et $Sp_{2k}(\mathbb{Z}/(p^n\mathbb{Z}))$. Notre théoréme prolonge le travail de Landazuri et Seitz, qui considérent le degré minimal des représentations pour les groupes de Chevalley sur les corps finis, tout en offrant une preuve plus simple que la leur. La seconde partie de la thése à trait à la théorie algébrique des nombres. Un polynome monogéne $f$ est un polynome unitaire irréductible à coefficients entiers qui endengre un corps de nombres monogéne. Pour un nombre premier $q$ donné, nous allons montrer, en utilisant le théoréme de densité de Tchebotariov, que la densité des nombres premiers $p$ tels que $t^q -p$ soit monogéne est supérieure ou égale à $(q-1)/q$. Nous allons également démontrer que, quand $q=3$, la densité des nombres premiers $p$ tels que $\mathbb{Q}(\sqrt[3]{p})$ soit non monogéne est supérieure ou égale à $1/9$.
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Cette thèse est divisée en trois parties. Une première section présente les résultats de l'étude de la formation de polarons magnétiques liés (BMP) dans le ferroaimant EuB6 par diffusion de neutrons à petits angles (SANS). La nature magnétique du système ferromagnétique est observée sous une température critique de 15K. La signature des BMP n'apparaît pas dans la diffusion de neutrons, mais ces mesures permettent de confirmer une limite inférieure de 100\AA à la longueur de cohérence des BMP (xi_{Lower}). Dans un second temps, l'étude du LaRhSi3, un supraconducteur sans symétrie d'inversion, par muSR et ZF-muSR nous permet de sonder le comportement magnétique du système dans la phase supraconductrice. Aucun champ magnétique interne n'a été détecté en ZF-muSR sous la température critique (T_c = 2.2K). Cela indique que la phase supraconductrice ne porte pas de moment cinétique intrinsèque. L'analyse du spectre d'asymétrie sous l'application d'un champ magnétique externe nous apprend que le système est faiblement type II par l'apparition de la signature de domaines magnétiques typique d'un réseau de vortex entre H_{c1}(0) et H_{c2}(0), respectivement de 80+/- 5 et 169.0 +/- 0.5 G. Finalement, la troisième section porte sur l'étude du champ magnétique interne dans l'antiferroaimant organique NIT-2Py. L'observation d'une dépendance en température des champs magnétiques internes aux sites d'implantation muonique par ZF-muSR confirme la présence d'une interaction à longue portée entre les moments cinétiques moléculaires. Ces valeurs de champs internes, comparées aux calculs basés sur la densité de spins obtenue par calculs de la théorie de la fonctionnelle de la densité, indiquent que la moitié des molécules se dimérisent et ne contribuent pas à l'ordre antiferromagnétique. La fraction des molécules contribuant à l'ordre antiferromagnétique sous la température critique (T_c = 1.33 +/- 0.01K) forme des chaines uniformément polarisées selon l'axe (1 0 -2). Ces chaines interagissent antiferromagnétiquement entre elles le long de l'axe (0 1 0) et ferromagnétiquement entre les plan [-1 0 2].
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Remote Data acquisition and analysing systems developed for fisheries and related environmental studies have been reported. It consists of three units. The first one namely multichannel remote data acquisition system is installed at the remote place powered by a rechargeable battery. It acquires and stores the 16 channel environmental data on a battery backed up RAM. The second unit called the Field data analyser is used for insitue display and analysis of the data stored in the backed up RAM. The third unit namely Laboratory data analyser is an IBM compatible PC based unit for detailed analysis and interpretation of the data after bringing the RAM unit to the laboratory. The data collected using the system has been analysed and presented in the form of a graph. The system timer operated at negligibly low current, switches on the power to the entire remote operated system at prefixed time interval of 2 hours.Data storage at remote site on low power battery backedupRAM and retrieval and analysis of data using PC are the special i ty of the system. The remote operated system takes about 7 seconds including the 5 second stabilization time to acquire and store data and is very ideal for remote operation on rechargeable bat tery. The system can store 16 channel data scanned at 2 hour interval for 10 days on 2K backed up RAM with memory expansion facility for 8K RAM.
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En base a los datos obtenidos por distintos estudios sobre las diversas lenguas respecto a los procesos cognitivos que intervienen en la lectura, hacer una aportación desde la lengua castellana en uno de estos procesos cognitivos: las propiedades relevantes del estímulo (letras) que sirven para la identificación y su posterior reconocimiento. Cuatro alumnos de tercer curso de Psicología de la Universidad de Murcia, elegidos aleatoriamente y sin distinción de sexo por no haber evidencia empírica sobre influencia de esta variable. Se presentaron a los sujetos los dos tipos de escritura (Courier 10 y Script) en dos alfabetos aleatorios en cada tipo. La experiencia duró una hora y media por sujeto, con paradas de quince minutos tras veinte diapositivas. Se recogieron los resultados, número de aciertos y de errores para su posterior análisis. Dos series de 27 letras minúsculas mecanografiadas de una máquina IBM, tipo Courier 10 y Script, ambos difieren notablemente y se pretendía comprobar si ello implica una diferencia en el tipo de indicios relevantes utilizados en el reconocimiento de letras o bien éstos permanecen invariantes en un tipo de letra u otro. Diapositivas. Taquistoscopio Kodak Ektagraphic modelo AF-2K. Agrupación de los resultados para someterles a un análisis comparativo según los modelos de Bouma, Kuennapas y Janson y Massaro. Ninguno de los modelos comparados con nuestros datos explican los datos encontrados. Puede ser debido a una inadecuación de dichos modelos para explicar cuáles son las características de las letras que sirven como indicio en el reconocimiento de las letras, o bien que todavía no se ha encontrado un procedimiento experimental adecuado para obtener evidencia empírica. Será necesario mucha investigación para obtener la información necesaria acerca de cuáles son las características relevantes en el reconocimiento de las letras.
Resumo:
Demostrar hasta qué punto la detección de un estímulo con alguna mutilación en el contexto de un conjunto de letras es mejor o peor en función de que dicho conjunto de letras formen palabras con sentido en castellano, o formen no-palabras (palabras sin ningún sentido). La idea fundamental del trabajo es saber en qué etapa de procesamiento se encuentra el llamado efecto de superioridad de la palabra. Las hipótesis fundamentales son las mismas que las planteadas por Krueger (1979). Cuatro sujetos (dos hombres y dos mujeres) de quinto de Psicología elegidos aleatoriamente. Los sujetos no conocieron cuales eran los propósitos del experimento hasta que éste no hubo terminado. Diseño factorial intrasujetos denominado 'diseño experimental tratamientos por tratamientos por sujetos'. El diseño quedó constituido con variables independientes (palabras usuales, no-palabras; y cinco tipos de exposición) con cuatro medidas repetidas de factor (los cuatro sujetos). Diseño 2 x 5 x 4. La medida de la variable dependiente se realizó transformando las proposiciones de cada uno de los sujetos en cada uno de los niveles de tratamiento. Seis listas de palabras o no-palabras. Cada lista contenía una serie de cinco palabras o no-palabras de seis letras cada una, pudiendo haber en una de ellas un tipo de mutilación en la 3 ó la 4, posición, tanto para la letra 'E' como para la letra 'B'. Cada una de las listas podía presentarse en cinco tiempos de exposición (10 mseg; 20 mseg; 40 mseg; 100 mseg y 500 mseg) indistinta y contra balanceadamente. Las tarjetas estímulo se presentan con un taquistoscopio Kodak Eckagraphic modelo AF-2K. Se utilizaron los negativos de las fotografías de 40 tarjetas para las palabras y 40 para las no-palabras y las mutilaciones correspondientes. La medida de la variable dependiente se obtuvo mediante las tablas de trasformación Arcoseno (manual de tablas estadísticas de W.M. Meredith, 1969), con la fórmula siguiente: '2 Arcoseno X'. Con las transformaciones obtenidas se llevó a cabo un análisis de varianza con las siguientes especificaciones: postulación de un modelo con dos efectos fijos y no aleatorios. Siete hipótesis nulas referentales a las combinaciones de los 3 factores implicados: factor A (palabras-no-palabras), factor B (tiempo de exposición), factor S (transformaciones sobre las respuestas de los 4 sujetos). No se ha podido comprobar ninguna de las hipótesis planteadas. Se confirman las hipótesis nulas, es decir, la no existencia de diferencias significativas entre los niveles de cada uno de los factores y los factores entre sí. Lo único que podemos llegar a concluir es la inexistencia del efecto a un nivel de mera detección de características, pero ni siquiera esta conclusión podría ser adecuada ya que no existen diferencias entre ninguno de los tiempos de exposición. Ha habido variables contaminantes que pudieron afectar a los resultados, hecho a tener en cuenta en el planteamiento de futuras investigaciones.
Resumo:
Carbon tetrafluoride (CF4) is included as a greenhouse gas within the Kyoto Protocol. There are significant discrepancies in the reported integrated infrared (IR) absorption cross section of CF4 leading to uncertainty in its contribution to climate change. To reduce this uncertainty, the IR spectrum of CF4 was measured in two different laboratories, in 0 933 hPa of air diluent at 296 +/- 2K over the wavelength range 600-3700 cm(-1) using spectral resolutions of 0.03 or 0.50 cm(-1). There was no discernable effect of diluent gas pressure or spectral resolution on the integrated IR absorption, and a value of the integrated absorption cross section of (1.90 +/- 0.17) x 10(-16) cm(2) molecule(-1) cm(-1) was derived. The radiative efficiency (radiative forcing per ppbv) and GWP (relative to CO2) of CF4 were calculated to be 0.102 W m(-2) ppbv(-1) and 7200 (100 year time horizon). The GWP for CF4 calculated herein is approximately 30% greater than that given by the Intergovernmental Panel on Climate Change (IPCC) [ 2002] partly due to what we believe to be an erroneously low value for the IR absorption strength of CF4 assumed in the calculations adopted by the IPCC. The radiative efficiency of CF4 is predicted to decrease by up to 40% as the CF4 forcing starts to saturate and overlapping absorption by CH4, H2O, and N2O in the atmosphere increases over the period 1750-2100. The radiative forcing attributable to increased CF4 levels in the atmosphere from 1750 to 2000 is estimated to be 0.004 W m(-2) and is predicted to be up to 0.033 W m(-2) from 2000 to 2100, dependent on the scenario.