825 research outputs found

    Pengaruh Model Numbered Head Together Dalam Pembelajaran IPS Terhadap Hasil Belajar Siswa Mis Bawari

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    The problem of this research is "Is there any influence of using Numbered Head Together model in IPS learning toward student learning result class V Mis Bawari Pontianak City?". The research method used is experimental method. The form of research is quasi experiment (Quasi Experimental Design) with the experimental design Nonequivalent Control Group Design. The population and its sample are VA class students and VB Mis Bawari Pontianak City which consists of 28 students of VA class (control class) and 28 students of VB class (experimental class). The research instrument used in the form of test questions in the form of multiple choice with the number of 60 questions. The average post test class test results were 76.90 and the average post test class test result was 66.90. The result of t test is obtained tcount 3,8553 and ttable α = 5% (with dk = 28 + 28 - 2 = 54) equal to 1.6619, which means tcount (3.8553)> ttable (1.6619), then Ha be accepted. This is the influence of the use of Numbered Head Together model in the social studies learning on the results of students of class V Mis Bawari Pontianak City. Calculation effect size (ES), obtained ES of 1.03 (high criteria). This means that the use of Numbered Head Together model gives a high influence on the students' IPS learning outcomes in class V Mis Bawari Pontianak City

    Working with simple machines

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    A set of examples is provided that illustrate the use of work as applied to simple machines. The ramp, pulley, lever and hydraulic press are common experiences in the life of a student and their theoretical analysis therefore makes the abstract concept of work more real. The mechanical advantage of each of these systems is also discussed so that students can evaluate their usefulness as machines.Comment: 9 pages, 4 figure

    O(k)O(k)-Equivariant Dimensionality Reduction on Stiefel Manifolds

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    Many real-world datasets live on high-dimensional Stiefel and Grassmannian manifolds, Vk(RN)V_k(\mathbb{R}^N) and Gr(k,RN)Gr(k, \mathbb{R}^N) respectively, and benefit from projection onto lower-dimensional Stiefel (respectively, Grassmannian) manifolds. In this work, we propose an algorithm called Principal Stiefel Coordinates (PSC) to reduce data dimensionality from Vk(RN) V_k(\mathbb{R}^N) to Vk(Rn)V_k(\mathbb{R}^n) in an O(k)O(k)-equivariant manner (k≀nâ‰ȘNk \leq n \ll N). We begin by observing that each element α∈Vn(RN)\alpha \in V_n(\mathbb{R}^N) defines an isometric embedding of Vk(Rn)V_k(\mathbb{R}^n) into Vk(RN)V_k(\mathbb{R}^N). Next, we optimize for such an embedding map that minimizes data fit error by warm-starting with the output of principal component analysis (PCA) and applying gradient descent. Then, we define a continuous and O(k)O(k)-equivariant map πα\pi_\alpha that acts as a ``closest point operator'' to project the data onto the image of Vk(Rn)V_k(\mathbb{R}^n) in Vk(RN)V_k(\mathbb{R}^N) under the embedding determined by α\alpha, while minimizing distortion. Because this dimensionality reduction is O(k)O(k)-equivariant, these results extend to Grassmannian manifolds as well. Lastly, we show that the PCA output globally minimizes projection error in a noiseless setting, but that our algorithm achieves a meaningfully different and improved outcome when the data does not lie exactly on the image of a linearly embedded lower-dimensional Stiefel manifold as above. Multiple numerical experiments using synthetic and real-world data are performed.Comment: 26 pages, 8 figures, comments welcome

    Understanding the interactions of cellulose fibres and deep eutectic solvent of choline chloride and urea

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    This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.A deep eutectic solvent composed of choline chloride (ChCl) and urea has been recently introduced as a promising cellulose compatible medium that enables e.g. fibre spinning. This paper clarifies the influence of such a solvent system on the structure and chemical composition of the cellulosic pulp fibres. Special emphasis was placed on the probable alterations of the chemical composition due to the dissolution of the fibre components and/or due to the chemical derivatisation taking place during the DES treatment. Possible changes in fibre morphology were studied with atomic force microscopy and scanning electron microscopy. Chemical compositions of pulp fibres were determined from the carbohydrate content, and by analysing the elemental content. Detailed structural characterisation of the fibres was carried out using spectroscopic methods; namely X-Ray Photoelectron Spectroscopy, solid state Nuclear Magnetic Resonance and Raman Spectroscopy. No changes with respect to fibre morphology were revealed and negligible changes in the carbohydrate composition were noted. The most significant change was related to the nitrogen content of the pulp after the DES treatment. Comprehensive examination using spectroscopic methods revealed that the nitrogen originated from strongly bound ChCl residuals that could not be removed with a mild ethanol washing procedure. According to Raman spectroscopic data and methylene blue adsorption tests, the cationic groups of ChCl seems to be attached to the anionic groups of pulp by electrostatic forces. These findings will facilitate the efficient utilisation of DES as a cellulose compatible medium without significantly affecting the native fibre structure.The authors acknowledge the Finnish Funding Agency for Innovation (TEKES) for funding the work via Design Driven Value Chains in the World of Cellulose 2.0 project. The Academy of Finland (Project ID 300367) is acknowledged for enabling the research mobility of T.T. to the University of Exeter, UK. Unto Tapper (VTT) is thanked for the SEM imaging, Atte Mikkelson, Ritva Heinonen and Marita Ikonen (VTT) for the chemical analysis and Robertus Nugroho (Aalto University) for the AFM imaging

    Structure of 13^{13}Be probed via secondary beam reactions

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    The low-lying level structure of the unbound neutron-rich nucleus 13^{13}Be has been investigated via breakup on a carbon target of secondary beams of 14,15^{14,15}B at 35 MeV/nucleon. The coincident detection of the beam velocity 12^{12}Be fragments and neutrons permitted the invariant mass of the 12^{12}Be+nn and 12^{12}Be+nn+nn systems to be reconstructed. In the case of the breakup of 15^{15}B, a very narrow structure at threshold was observed in the 12^{12}Be+nn channel. Contrary to earlier stable beam fragmentation studies which identified this as a strongly interacting ss-wave virtual state in 13^{13}Be, analysis here of the 12^{12}Be+nn+nn events demonstrated that this was an artifact resulting from the sequential-decay of the 14^{14}Be(2+^+) state. Single-proton removal from 14^{14}B was found to populate a broad low-lying structure some 0.70 MeV above the neutron-decay threshold in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)ℏω\hbar\omega shell-model calculations, the low-lying structure is concluded to most probably arise from closely spaced Jπ^\pi=1/2+^+ and 5/2+^+ resonances (Er_r=0.40±\pm0.03 and 0.85−0.11+0.15^{+0.15}_{-0.11} MeV), whilst the broad higher-lying feature is a second 5/2+^+ level (Er_r=2.35±\pm0.14 MeV). Taken in conjunction with earlier studies, it would appear that the lowest 1/2+^+ and 1/2−^- levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical Review

    Direct reaction measurements with a 132Sn radioactive ion beam

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    The (d,p) neutron transfer and (d,d) elastic scattering reactions were measured in inverse kinematics using a radioactive ion beam of 132Sn at 630 MeV. The elastic scattering data were taken in a region where Rutherford scattering dominated the reaction, and nuclear effects account for less than 8% of the cross section. The magnitude of the nuclear effects was found to be independent of the optical potential used, allowing the transfer data to be normalized in a reliable manner. The neutron-transfer reaction populated a previously unmeasured state at 1363 keV, which is most likely the single-particle 3p1/2 state expected above the N=82 shell closure. The data were analyzed using finite range adiabatic wave calculations and the results compared with the previous analysis using the distorted wave Born approximation. Angular distributions for the ground and first excited states are consistent with the previous tentative spin and parity assignments. Spectroscopic factors extracted from the differential cross sections are similar to those found for the one neutron states beyond the benchmark doubly-magic nucleus 208Pb.Comment: 22 pages, 7 figure

    Biodegradable nanomats produced by electrospinning : expanding multifunctionality and potential for tissue engineering

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    With increasing interest in nanotechnology, development of nanofibers (n-fibers) by using the technique of electrospinning is gaining new momentum. Among important potential applications of n-fiber-based structures, scaffolds for tissue-engineering represent an advancing front. Nanoscaffolds (n-scaffolds) are closer to natural extracellular matrix (ECM) and its nanoscale fibrous structure. Although the technique of electrospinning is relatively old, various improvements have been made in the last decades to explore the spinning of submicron fibers from biodegradable polymers and to develop also multifunctional drug-releasing and bioactive scaffolds. Various factors can affect the properties of resulting nanostructures that can be classified into three main categories, namely: (1) Substrate related, (2) Apparatus related, and (3) Environment related factors. Developed n-scaffolds were tested for their cytocompatibility using different cell models and were seeded with cells for to develop tissue engineering constructs. Most importantly, studies have looked at the potential of using n-scaffolds for the development of blood vessels. There is a large area ahead for further applications and development of the field. For instance, multifunctional scaffolds that can be used as controlled delivery system do have a potential and have yet to be investigated for engineering of various tissues. So far, in vivo data on n-scaffolds are scarce, but in future reports are expected to emerge. With the convergence of the fields of nanotechnology, drug release and tissue engineering, new solutions could be found for the current limitations of tissue engineering scaffolds, which may enhance their functionality upon in vivo implantation. In this paper electrospinning process, factors affecting it, used polymers, developed n-scaffolds and their characterization are reviewed with focus on application in tissue engineering

    <i>C-elegans</i> model identifies genetic modifiers of alpha-synuclein inclusion formation during aging

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    Inclusions in the brain containing alpha-synuclein are the pathological hallmark of Parkinson's disease, but how these inclusions are formed and how this links to disease is poorly understood. We have developed a &lt;i&gt;C-elegans&lt;/i&gt; model that makes it possible to monitor, in living animals, the formation of alpha-synuclein inclusions. In worms of old age, inclusions contain aggregated alpha-synuclein, resembling a critical pathological feature. We used genome-wide RNA interference to identify processes involved in inclusion formation, and identified 80 genes that, when knocked down, resulted in a premature increase in the number of inclusions. Quality control and vesicle-trafficking genes expressed in the ER/Golgi complex and vesicular compartments were overrepresented, indicating a specific role for these processes in alpha-synuclein inclusion formation. Suppressors include aging-associated genes, such as sir-2.1/SIRT1 and lagr-1/LASS2. Altogether, our data suggest a link between alpha-synuclein inclusion formation and cellular aging, likely through an endomembrane-related mechanism. The processes and genes identified here present a framework for further study of the disease mechanism and provide candidate susceptibility genes and drug targets for Parkinson's disease and other alpha-synuclein related disorders
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