2,362 research outputs found

    Distributed bounded-error state estimation for partitioned systems based on practical robust positive invariance

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    We propose a partition-based state estimator for linear discrete-time systems composed by coupled subsystems affected by bounded disturbances. The architecture is distributed in the sense that each subsystem is equipped with a local state estimator that exploits suitable pieces of information from parent subsystems. Moreover, differently from methods based on moving horizon estimation, our approach does not require the on-line solution to optimization problems. Our state-estimation scheme, that is based on the notion of practical robust positive invariance developed in Rakovic 2011, also guarantees satisfaction of constraints on local estimation errors and it can be updated with a limited computational effort when subsystems are added or removed

    Comparison of Students' Scientific Literacy in Integrated Science Learning Through Model of Guided Discovery and Problem Based Learning

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    This study aims to describe the comparison of students' scientific literacy improvement in integrated science learning through guided dicovery and problem based learning models. The subjects were 8th grade students of State Junior High Schools in Bandung. This research design was quasi-experimental with non randomaized static group pretest-posttest design. The instrument used in this study was multiple choice test and attitude scale. The result shows that the improvement of scientific literacy achievement of students who learned integrated science through guided discovery and problem based learning models did not differ significantly. Integrated science learning through guided disovery models can improve student literacy achievement with the gain of 0.37 (medium category), while by using problem based learning model can improve scientific literacy with the gain of 0.41 (medium category). It can be concluded that the both models of guided discovery and problem based learning can improve students' science literacy

    Resonant Transport in Nb/GaAs/AlGaAs/GaAs Microstructures

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    Resonant transport in a hybrid semiconductor-superconductor microstructure grown by MBE on GaAs is presented. This structure experimentally realizes the prototype system originally proposed by de Gennes and Saint-James in 1963 in \emph{all}-metal structures. A low temperature single peak superimposed to the characteristic Andreev-dominated subgap conductance represents the mark of such resonant behavior. Random matrix theory of quantum transport was employed in order to analyze the observed magnetotransport properties and ballistic effects were included by directly solving the Bogoliubov-de Gennes equations.Comment: 7 pages REVTeX, 4 figures, to be published by World Scientific in Proceedings of International Symposium on Mesoscopic Superconductivity and Spintronics (NTT R&D Center Atsugi, Japan, March 2002

    Identify Scientific Literacy From the Science Teachers' Perspective

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    Scientific literacy is considered as a benchmark of high and low quality of science education in a country. This study aims to identify the scientific literacy of teachers and learning science relation to the issues from the perspective of a science teacher. This descriptive study involved 25 science teachers who are members of MGMP IPA in Bogor. The instrument used in this study consisted of scientific literacy tests and interviews. The results showed that 20% of teachers have scientific literacy ability in the low category, 65% in the moderate category and 15% in the high category. The problems of teaching science based on teacher perspective are 1. having difficulty to teach Integrated Science; 2. having limited knowledge related to learning models of Integrated Science; 3. lack of motivation in teaching integrated science consistently. The results of these studies form the basis that the professional trainings for junior high science teacher need to be conducted in a sustainable manner and related with the needs of their proficiency

    Lapex: A Phoswich balloon experiment for hard X-ray astronomy

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    Satellite and balloon observations have shown that several classes of celestial objects are hard ( 15 keV) energy band with a sensitivity of approx 10 mCrab has been performed with the UCSD/MIT instrument (A4) on board the HEAO 1 satellite. About 70 X-ray sources were detected, including galactic and extragalactic objects. Hard X-ray emission has been detected in the Galaxy from X-ray pulsars. Extragalactic sources of hard X-ray emission include clusters of galaxies, QSOs, BL Lac objects, Seyfert galaxies. The essential characteristics of the Large Area Phoswich Experiment (LAPEX) for crowded sky field observations are described. It has: (1) a broad energy band of operation (20-300 keV); (2) a 3 sigma sensitivity of about 1 mCrab in 10,000 s of live observing time; and (3) imaging capabilities with an angular resolution of about 20'

    The Mn site in Mn-doped Ga-As nanowires: an EXAFS study

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    We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs nanowires. Mn doping has been obtained either via the diffusion of the Mn used as seed for the nanowire growth or by providing Mn during the growth of Au-induced wires. As a general finding, we observe that Mn forms chemical bonds with As but is not incorporated in a substitutional site. In Mn-induced GaAs wires, Mn is mostly found bonded to As in a rather disordered environment and with a stretched bond length, reminiscent of that exhibited by MnAs phases. In Au-seeded nanowires, along with stretched Mn-As coordination we have found the presence of Mn in a Mn-Au intermetallic compound.Comment: This is an author-created, un-copyedited version of an article accepted for publication in Semiconductor Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version is available online at doi:10.1088/0268-1242/27/8/08500

    Resonant spin-dependent electron coupling in a III-V/II-VI heterovalent double quantum well

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    We report on design, fabrication, and magnetooptical studies of a III-V/II-VI hybrid structure containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well (QW). The structure design allows one to tune the QW levels into the resonance, thus facilitating penetration of the electron wave function from the diluted magnetic semiconductor ZnCdMnSe QW into the nonmagnetic GaAs QW and vice versa. Magneto-photoluminescence studies demonstrate level anticrossing and strong intermixing resulting in a drastic renormalization of the electron effective g factor, in perfect agreement with the energy level calculations.Comment: 4 pages, 5 Postscript figures, uses revtex

    Evolution of a fluorinated green fluorescent protein

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    The fluorescence of bacterial cells expressing a variant (GFPm) of the green fluorescent protein (GFP) was reduced to background levels by global replacement of the leucine residues of GFPm by 5,5,5-trifluoroleucine. Eleven rounds of random mutagenesis and screening via fluorescence-activated cell sorting yielded a GFP mutant containing 20 amino acid substitutions. The mutant protein in fluorinated form showed improved folding efficiency both in vivo and in vitro, and the median fluorescence of cells expressing the fluorinated protein was improved {approx}650-fold in comparison to that of cells expressing fluorinated GFPm. The success of this approach demonstrates the feasibility of engineering functional proteins containing many copies of abiological amino acid constituents

    ENDOCANNABINOIDS CB1 AND CB2: A POSSIBLE ROLE IN ORAL SQUAMOUS CELL CARCINOMA PATHOGENESIS

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    Aim. Cancer of the oral cavity is the eighth most common malignancy in the world. The disease is diagnosed after a considerable delay and predict the individual progression is difficult. The improvements of the therapy did not increased the rate of survival at 5 years, that is still about 50%. The identification of the possible markers that indicates the progression of the tumor is therefore necessary. Endocannabinoids may play an important role in the process of carcinogenesis in the oral mucosa. They are able to bind and activate specific membrane receptors coupled to G proteins, cannabinoid receptors CB1 and CB2. The purpose of this study is to evaluate the expression of CB1 and CB2 receptors in the development of oral cancer through the immunohistochemical study on samples of OSCC. Materials and methods. We selected 44 cases of patients with the primary tumor in the oral cavity. The stage of the tumor was classified according to the TNM system. The tumors grading was divided into I, II and III grade. The paraffin sections were analyzed by immunohistochemistry. The assessment of the immunoreactivity for CB1 and CB2 receptors was weak or strong. For quantitative analysis the expression of CB1 and CB2 receptors was evaluated in percentage with scale of values ??ranging from 0 to 100%. Results. The immunohistochemical examination of the samples analyzed showed the absence of expression of CB1 and CB2 receptors in normal mucosa, while peritumoral mucosa showed a weak expression in the vicinity of cancer and tumor mucosa showed an overexpression of receptors. Furthermore, the intensity of staining increased with the increase of the grading. It can be concluded that the strong immunoreactivity of CB1 and CB2 receptors is related to aggressive behavior of oral carcinoma. Conclusions. The analysis of endocannabinoids and their receptors on tissue biopsies taken from carcinoma of the oral cavity may therefore indicate future therapeutic targets and new prognostic biomarkers in these patients, especially in the early stages of the disease. The ultimate goal of this work is to indicate the possible role of CB1 and CB2 receptors such as tumor biomarker that may help in the early diagnosis of oral cancer and therefore contribute to reduce drastically the mortality of this disease

    Suppression of Antiferromagnetic Order by Light Hole Doping in La_2Cu_{1-x}Li_xO_4: A ^{139}La NQR Study

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    ^{139}La nuclear quadrupole resonance measurements in lightly doped La_2Cu_{1-x}Li_xO_4 have been performed to reveal the dependence of the magnetic properties of the antiferromagnetic CuO_2 planes on the character of the doped holes and their interactions with the dopant. A detailed study shows that the magnetic properties are remarkably insensitive to the character of the dopant impurity. This indicates that the added holes form previously unrecognized collective structures.Comment: 4 pages, 3 figures. Slightly modified version, as accepted for publication in Physical Review Letter
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