Nanoscale buckling deformation in layered copolymer materials

In layered materials, a common mode of deformation involves buckling of the layers under tensile deformation in the direction perpendicular to the layers. The instability mechanism, which operates in elastic materials from geological to nanometer scales, involves the elastic contrast between different layers. In a regular stacking of "hard" and "soft" layers, the tensile stress is first accommodated by a large deformation of the soft layers. The inhibited Poisson contraction results in a compressive stress in the direction transverse to the tensile deformation axis. The hard layers sustain this transverse compression until buckling takes place and results in an undulated structure. Using molecular simulations, we demonstrate this scenario for a material made of triblock copolymers. The buckling deformation is observed to take place at the nanoscale, at a wavelength that depends on strain rate. In contrast to what is commonly assumed, the wavelength of the undulation is not determined by defects in the microstructure. Rather, it results from kinetic effects, with a competition between the rate of strain and the growth rate of the instability. http://www.pnas.org/content/early/2011/12/23/1111367109.abstrac

“Penerapan Metode Pembelajaran Kooperatif Tipe Numbered Heads Together (NHT) Untuk Meningkatkan Keaktifan Siswa Dalam Bermain Bola voli Bagi Siswa Kelas VIIIB di SMP 16 Surakarta Tahun Ajaran 2016/2017”.

PENERAPAN METODE PEMBELAJARAN KOOPERATIF TIPE NUMBERED HEADS TOGETHER (NHT) UNTUK MENINGKATKAN KEAKTIFAN BERMAIN BOLAVOLI BAGI SISWA KELAS VIIIB DI SMP NEGERI 16 SURAKARTA TAHUN AJARAN 2016/2017 Naskah Publikasi Untuk memenuhi sebagian persyaratan Guna memperoleh gelar Sarjana Pendidikan Oleh: RATIH KUMALA SARI K4612118 FAKULTAS KEGURUAN DAN ILMU PENDIDIKAN UNIVERSITAS SEBELAS MARET SURAKARTA November 2016 PENERAPAN METODE PEMBELAJARAN KOOPERATIF TIPE NUMBERED HEADS TOGETHER (NHT) UNTUK MENINGKATKAN KEAKTIFAN BERMAIN BOLAVOLI BAGI SISWA KELAS VIIIB DI SMP NEGERI 16 SURAKARTA TAHUN AJARAN 2016/2017 ABSTRAK Ratih Kumala Sari, Hanik Liskustyawati, Sri Santoso Sabarini, Fakultas Keguruan dan Ilmu Pendidikan, Universitas Sebelas Maret Surakarta Surakarta 57126, Jawa Tengah, Indonesia Email: [email protected] Tujuan Penelitian ini adalah untuk meningkatkan keaktifanbermain bolavoli pada peserta didik kelas VIII-B SMP Negeri 16 Surakarta tahun ajaran 2016/2017 melalui penerapan metode pembelajaran kooperatif tipe Numbered Heads Together (NHT). Penelitian ini merupakan penelitian tindakan kelas (PTK).Penelitian ini dilaksanakan dalam dua siklus,dengan tiap siklus terdiri atas perencanaan, pelaksanaan tindakan, observasi, dan refleksi. Subjek penelitian adalah peserta didik kelas VIII-B SMP Negeri 16 Surakarta tahun ajaran 2016/2017 yang berjumlah 30 peserta didik yang terdiri dari 12 peserta didik putra dan 18peserta didik putri. Sumber data berasal dari guru, peserta didik dan peneliti.Teknik pengumpulan data adalah dengan observasi,angket keaktifan bolavoli, dokumentasi atau arsipberupafotodanvidio. Validasi instrument menggunakan SPSS.Analisis data yang diperoleh dianalisis secara deskriptif kualitatif.Prosedur penelitian adalah berupasikluspembelajaran yang saling berkaitan. Berdasarkan hasil analisis data pada bab IV diperoleh peningkatan yang signifikan terjadi pada prasiklus ke siklus I dan dari siklus I ke siklus IIHal ini dilihat dari pengamatan observer sebanyak 3 orang pada masing-masing siklus bahwa pada siklus 1 dari 75,95% meningkat pada siklus II menjadi 82,18. Hasil ini menunjukkan bahwa kemampuan saat melakukan gerakan sebagai bentuk klarifikasi dari suatu jawaban yang ditemukan dari proses pembelajaran dengan metode NHT secara diamati saat pembelajaran bolavoli berlangsung atau diukur dengan angket keaktifan dengan menggunakan metode NHT telah mencapai persentase target akhir pencapaian sebesar 80%. Dari hasil analisis data diatas dapat disimpulan bahwa penerapan metode Numbered Heads Together (NHT) dapat meningkatkan keaktifanbermain bolavoli pada peserta didik kelas VIII-B SMP Negeri 16Surakarta tahun ajaran 2016/2017. Kata Kunci : Keaktifan, Bermain Bolavoli, Penerapan Metode Numbered Heads Together

Polymer Chain Generation for Coarse-Grained Models Using Radical-Like Polymerization

International audienceThis paper presents major improvements in the efficiency of the so-called Radical-Like Polymerization (RLP) algorithm proposed in ”Polymer chain generation for coarse-grained models using radical-like polymerization” [J. Chem. Phys. 128 (2008)]. Three enhancements are detailed in this paper: (1) the capture radius of a radical is enlarged to increase the probability of finding a neighboring monomer; (2) between each growth step, equilibration is now performed with increasing the relaxation time depending on the actual chain size; (3) the RLP algorithm is now fully parallelized and proposed as a “fix” within the “Lammps” molecular dynamics simulation suite

Finsler geometry modeling of reverse piezoelectric effect in PVDF

We apply the Finsler geometry (FG) modeling technique to study the electric field-induced strain in ferroelectric polymers. Polyvinylidene difluoride (PVDF) has a negative longitudinal piezoelectric coefficient, which is unusual in ferroelectrics, and therefore the shape changes in this material are hard to predict. We find that the results of Monte Carlo simulations for the FG model are in good agreement with experimental strain-electric field curves of PVDF-based polymers in both longitudinal and transverse directions. This implies that FG modeling is suitable for reproducing the reverse piezoelectric effect in PVDF

On the Mass Spectrum of the SU(2) Higgs Model in 2+1 Dimensions

We calculate the masses of the low-lying states with quantum numbers $J^{PC}=0^{++},1^{--}$ in the Higgs and confinement regions of the three-dimensional SU(2) Higgs model, which plays an important r\^ole in the description of the thermodynamic properties of the standard model at finite temperatures. We extract the masses from correlation functions of gauge-invariant operators which are calculated by means of a lattice Monte Carlo simulation. The projection properties of our lattice operators onto the lowest states are greatly improved by the use of smearing techniques. We also consider cross correlations between various operators with the same quantum numbers. From these the mass eigenstates are determined by means of a variational calculation. In the symmetric phase, we find that some of the ground state masses are about 30\% lighter than those reported from previous simulations. We also obtain the masses of the first few excited states in the symmetric phase. Remarkable among these is the occurrence of a $0^{++}$ state composed almost entirely of gauge degrees of freedom. The mass of this state, as well as that of its first excitations, is nearly identical to the corresponding glueball states in three-dimensional SU(2) pure gauge theory, indicating an approximate decoupling of the pure gauge sector from the Higgs sector of the model. We perform a detailed study of finite size effects and extrapolate the lattice mass spectrum to the continuum.Comment: 30 pages LATEX, uses epsf.st

Thermal gradient of in-flight polymer particles during cold spraying

International audienceThe manufacture of polymer coatings via the cold-spray process remains challenging owing to the viscoelastic-viscoplastic behavior exhibited by polymers. One crucial step to improve cold-spray polymer coating is to determine the particles' thermal history during their flight from inside the nozzle to their impact on the substrate. In this study, we propose estimating the velocity and temperature of an isolated polymer particle traveling through a nozzle with a sharp change in its cross-section. The preliminary results show that the geometric discontinuity constricts the flow, thereby increasing the particle velocity. Moreover, a significant thermal gradient is expected inside the particle, which in turn leads to a gradient of mechanical properties of the polymeric particle during impact

The coronal line regions of planetary nebulae NGC6302 and NGC6537: 3-13um grating and echelle spectroscopy

We report on advances in the study of the cores of NGC6302 and NGC6537 using infrared grating and echelle spectroscopy. In NGC6302, emission lines from species spanning a large range of ionization potential, and in particular [SiIX]3.934um, are interpreted using photoionization models (including CLOUDY), which allow us to reestimate the central star's temperature to be about 250000K. All of the detected lines are consistent with this value, except for [AlV] and [AlVI]. Aluminium is found to be depleted to one hundredth of the solar abundance, which provides further evidence for some dust being mixed with the highly ionized gas (with photons harder than 154eV). A similar depletion pattern is observed in NGC6537. Echelle spectroscopy of IR coronal ions in NGC6302 reveals a stratified structure in ionization potential, which confirms photoionization to be the dominant ionization mechanism. The lines are narrow (< 22km/s FWHM), with no evidence of the broad wings found in optical lines from species with similar ionization potentials, such as [NeV]3426A. We note the absence of a hot bubble, or a wind blown bipolar cavity filled with a hot plasma, at least on 1'' and 10km/s scales. We also provide accurate new wavelengths for several of the infrared coronal lines observed with the echelle.Comment: Accepted for publication in MNRA

Prediction of function in daily life following multidisciplinary rehabilitation for individuals with chronic musculoskeletal pain; a prospective study

Background: The prevalence of chronic musculoskeletal pain is high, with widespread negative economic, psychological, and social consequences for the individual. It is therefore important to find ways to predict the outcome of rehabilitation programmes in terms of function in daily life. The aims of this study were to investigate the improvements over time from multidisciplinary rehabilitation in terms of pain and function, and analyse the relative impact of individual and psychosocial factors as predictors of function in daily life in individuals with chronic musculoskeletal pain. Methods: A prospective study was conducted among one hundred and forty three (N = 143) musculoskeletal pain patients. Measures of pain, function, and functional health status were obtained at baseline, after 5 weeks of intensive training, at the end of the 57-week rehabilitation programme, and at a 1 year follow-up, using validated self-administrated measures. Linear regression analysis was applied to investigate the relative impact of musculoskeletal pain, individual- , and psychosocial factors in function. Results: The participants studied showed a significant increase in function during the 57 weeks rehabilitation period. There was also a significant increase in function from the end of the rehabilitation period (57th week) to the one year follow-up measures. Pain intensity associated significantly with pain experience over all measurement periods. High levels of pain intensity (β = .42**) and pain experience (β = .37*), and poor psychological capacity (β = -.68*) at baseline, as well as poor physiological capacity (β = -.44**) and high levels of anxiety (β = .48**) and depression (β = .58***) at the end of the rehabilitation program were the most important prognostic factors of variance in functioning over the 4 measurement periods. Conclusion: The data suggest that physical capacity, emotional distress and coping skills should be priority areas in rehabilitation programmes to improve functioning in daily life