Evidence for the Validity of the Berry-Robnik Surmise in a Periodically Pulsed Spin System

We study the statistical properties of the spectrum of a quantum dynamical system whose classical counterpart has a mixed phase space structure consisting of two regular regions separated by a chaotical one. We make use of a simple symmetry of the system to separate the eigenstates of the time-evolution operator into two classes in agreement with the Percival classification scheme \cite{Per}. We then use a method firstly developed by Bohigas et. al. \cite{BoUlTo} to evaluate the fractional measure of states belonging to the regular class, and finally present the level spacings statistics for each class which confirm the validity of the Berry-Robnik surmise in our model.Comment: 15 pages, 9 figures available upon request, Latex fil

Superconducting properties of MgB2 thin films prepared on flexible plastic substrates

Superconducting MgB2 thin films were prepared on 50-micrometer-thick, flexible polyamide Kapton-E foils by vacuum co-deposition of Mg and B precursors with nominal thickness of about 100 nm and a special ex-situ rapid annealing process in an Ar or vacuum atmosphere. In the optimal annealing process, the Mg-B films were heated to approximately 600 C, but at the same time, the backside of the structures was attached to a water-cooled radiator to avoid overheating of the plastic substrate. The resulting MgB2 films were amorphous with the onset of the superconducting transition at T_(c,on) about 33 K and the transition width of approximately 3 K. The critical current density was > 7x10^5 A/cm^2 at 4.2 K, and its temperature dependence indicated a granular film composition with a network of intergranular weak links. The films could be deposited on large-area foils (up to 400 cm^2) and, after processing, cut into any shapes (e.g., stripes) with scissors or bent multiple times, without any observed degradation of their superconducting properties.Comment: 3 figure

Educational strategies in data journalism: A comparative study of six European countries

The article explores training programs in higher education with regard to data journalism from a multi-national perspective. By carrying out a comparative analysis in six European countries (Germany, Switzerland, the Netherlands, Italy, Poland, and the United Kingdom), it covers different models of media systems and journalistic cultures envisaged by Hallin and Mancini. Based on a desk review and in-depth interviews with instructors of data journalism in each country, the article identifies different approaches to the way data journalism is taught. In Europe, such programs are offered by four types of organizations: academic, vocational, professional, and civic. The role played by those organizations can be explained as a result of the peculiarities of national media systems. But there are also commonalities, for example, non-academic institutions (such as the European Journalism Center or the Center for Investigative Journalism) and major international news outlets (such as The Guardian and The New York Times) seem to take over a leading role in all of the analyzed countries. Generally speaking, data journalism education appears to be a very young discipline that frequently neglects fundamental journalistic topics such as ethical issues, transparency, accountability, and responsiveness although they are crucial in a journalistic field as sophisticated tools to reveal hidden aspects of reality

Phonons in MgB2 by Polarized Raman Scattering on Single Crystals

The paper presents detailed Raman scattering study of the unusually broad E2g phonon mode in MgB2 crystal. For the first time, it is shown by the polarized Raman scattering on few-micron-size crystallites with natural faces that the observed broad Raman feature really does obey the selection rules of an E2g mode. Raman spectra on high quality polycrystalline superconducting MgB2 wires reveal a very symmetric E2g phonon line near 615 1/cm with the room temperature linewidth of 260 1/cm only. Additional scattering of different polarization dependence, observed in certain crystallites is interpreted as weighted phonon density of states induced by lattice imperfections.Comment: 4 pages + 7 figure

Preliminary Sunyaev Zel'dovich Observations of Galaxy Clusters with OCRA-p

We present 30 GHz Sunyaev Zel'dovich (SZ) observations of a sample of four galaxy clusters with a prototype of the One Centimetre Receiver Array (OCRA-p) which is mounted on the Torun 32-m telescope. The clusters (Cl0016+16, MS0451.6-0305, MS1054.4-0321 and Abell 2218) are popular SZ targets and serve as commissioning observations. All four are detected with clear significance (4-6 sigma) and values for the central temperature decrements are in good agreement with measurements reported in the literature. We believe that systematic effects are successfully suppressed by our observing strategy. The relatively short integration times required to obtain these results demonstrate the power of OCRA-p and its successors for future SZ studies.Comment: 9 pages, 2 figures. Accepted by MNRAS, online earl

Comparison of numerical and experimental strains distributions in composite panel for aerospace applications

In structural applications of aerospace industry, weight efficiency, understood as minimal weight and maximal stiffness, is of great importance. This criterion can be achieved by composite lightweight structures. Typical structures for aforementioned applications are sandwich panels (e.g., with honeycomb core) and stiffened panels (e.g., with blade ribs, T-bar ribs, or hat ribs). In this paper, a hat-stiffened panel, made of carbon/epoxy woven composite, is considered. Results of experiments, consisting of loading the panel and measuring exciting forces and strains (using strain gages), are presented. The results are compared to strains distribution obtained from finite element model of the panel.The research was partially funded from financial resources from the statutory subsidy of the Faculty of Mechanical Engineering, Silesian University of Technology, in 2021. W.M. acknowledges the National Agency for Academic Exchange of Poland (under the Academic International Partnerships program, grant agreement PPI/APM/2018/1/00004) for supporting training in the University of Minho, which enabled execution of the study

Penerapan Problem Based Learning (Pbl) Dengan Penilaian Portofolio Untuk Meningkatkan Keaktifan Dan Prestasi Belajar Pada Materi Stoikiometri Di SMA N 2 Surakarta Tahun Ajaran 2013/2014

Penelitian ini bertujuan untuk meningkatkan: 1). keaktifan belajar siswa kelas X IPA 5 pada materi konsep mol dan perhitungan kimia di SMA Negeri 2 Surakarta Tahun Ajaran 2013/2014, 2). prestasi belajar siswa kelas X IPA 5 pada materi konsep mol dan perhitungan kimia di SMA Negeri 2 Surakarta Tahun Ajaran 2013/2014. Penelitian ini merupakan Penelitian Tindakan Kelas (PTK) yang terdiri dari dua siklus. Setiap siklus terdapat empat tahapan yang terdiri dari perencanaan tindakan, pelaksanaan tindakan, observasi, refleksi. Subyek penelitian adalah siswa kelas X IPA 5 SMA Negeri 2 Surakarta Tahun Ajaran 2013/2014 yang berjumlah 32 siswa. Sumber data berasal dari guru, dan siswa. Data penelitian yang diperoleh berupa keaktifan siswa (visual activities, oral activities, listening activities, dan writing activities) dan prestasi belajar (aspek kognitif dan aspek sikap). Pengumpulan data adalah dengan metode tes (tertulis) dan non tes (observasi, wawancara, kajian dokumen, angket). Teknik analisis data penelitian secara deskriptif kualitataif dan kuantitatif. Berdasarkan hasil dari penelitian yang telah dilakukan, maka dapat diambil kesimpulan sebagai berikut: 1). penerapan model Problem Based Learning (PBL) dengan penilaian portofolio dapat meningkatkan keaktifan belajar siswa X IPA 5 pada materi konsep mol dan perhitungan kimia di SMA Negeri 2 Surakarta Tahun Ajaran 2013/2014. Persentase rata-rata nilai akhir keaktifan siswa siklus I dalam pembelajaran adalah 73,65 % meningkat menjadi 74,40 % pada siklus II, 2). penerapan model Problem Based Learning (PBL) dengan penilaian portofolio dapat meningkatkan prestasi belajar siswa X IPA 5 pada materi konsep mol dan perhitungan kimia di SMA Negeri 2 Surakarta Tahun Ajaran 2013/2014. Persentase rata-rata nilai akhir prestasi belajar siswa siklus I adalah 87,98 % meningkat menjadi 90,34 % pada siklus II dengan jumlah siswa tuntas sebanyak 32 siswa (100 %). Persentase rata-rata nilai akhir aspek sikap siswa pada siklus I adalah 70,99 % meningkat menjadi 75,7 % pada siklus II