Unsteady Crack Motion and Branching in a Phase-Field Model of Brittle Fracture

Crack propagation is studied numerically using a continuum phase-field approach to mode III brittle fracture. The results shed light on the physics that controls the speed of accelerating cracks and the characteristic branching instability at a fraction of the wave speed.Comment: 11 pages, 4 figure

Penerapan Konsep Pembelajaran Aktif, Kreatif, Efektif, Dan Menyenangkan (Pakem) Dalam Menyimak Puisi Untuk Meningkatkan Kemampuan Apresiasi Sastra

This research aimed to improve the students\u27 ability of literature through PAKEM concept in teaching learning process using picture cards to the students of PGSD S1 academic year 2010-2011. The research was the class action research with the research subject of all students of The Elementary School Teacher Education S1 academic year 2010-2011 class D, which consisted of 51 students, 16 male students, and 35 female students. The research process was done in two cycles; each cycle consisted of 2 meetings. Each meeting consisted of 2 lecture-hours (2x50 minutes). To know the first condition, it was conducted the pre-test, and the data of pre-test was used as the basic action of the fist cycle. After delivering the material of poem by applying the concept of PAKEM using the media of picture cards, it was continued by the post-test of the first cycle. The data of post- test I was used as the action of the second cycle, and it was ended by the analysis and the reflection of all cycles. The data collection was done by using test and non-test. Using test was by pre-test and post-test, and non-test was by observation, interview and documentation. The source used to process the data was score or from the quantitative data (the poem- writing score) and qualitative data. The result of the processing data was used to describe the achievement of the action towards the improvement of the students\u27 literature appreciation through PAKEM concept using the media of picture cards. It could be proven from the result of the research, observation and evaluation. After the action, it was proven that students\u27 literature appreciation improved in writing poem. In the cycle 1, it was found that 52% of the students were successful and 48% of them were not yet successful with the average point of 72. In the cycle 2, it, it was found that 75% of the students were successful and 20% of them were not yet successful with the average point of 77. Based on this description, it was concluded that the application of PAKEM concept using picture cards could improve the literature appreciation of S1 PGSD students in academic year 2010-2011. Key Words: active, creative, effective, and fun learning concept,listening to poem

Instability and Spatiotemporal Dynamics of Alternans in Paced Cardiac Tissue

We derive an equation that governs the spatiotemporal dynamics of small amplitude alternans in paced cardiac tissue. We show that a pattern-forming linear instability leads to the spontaneous formation of stationary or traveling waves whose nodes divide the tissue into regions with opposite phase of oscillation of action potential duration. This instability is important because it creates dynamically an heterogeneous electrical substrate for inducing fibrillation if the tissue size exceeds a fraction of the pattern wavelength. We compute this wavelength analytically as a function of three basic length scales characterizing dispersion and inter-cellular electrical coupling.Comment: 4 pages, 3 figures, submitted to PR

Eutectic Colony Formation: A Stability Analysis

Experiments have widely shown that a steady-state lamellar eutectic solidification front is destabilized on a scale much larger than the lamellar spacing by the rejection of a dilute ternary impurity and forms two-phase cells commonly referred to as `eutectic colonies'. We extend the stability analysis of Datye and Langer for a binary eutectic to include the effect of a ternary impurity. We find that the expressions for the critical onset velocity and morphological instability wavelength are analogous to those for the classic Mullins-Sekerka instability of a monophase planar interface, albeit with an effective surface tension that depends on the geometry of the lamellar interface and, non-trivially, on interlamellar diffusion. A qualitatively new aspect of this instability is the occurence of oscillatory modes due to the interplay between the destabilizing effect of the ternary impurity and the dynamical feedback of the local change in lamellar spacing on the front motion. In a transient regime, these modes lead to the formation of large scale oscillatory microstructures for which there is recent experimental evidence in a transparent organic system. Moreover, it is shown that the eutectic front dynamics on a scale larger than the lamellar spacing can be formulated as an effective monophase interface free boundary problem with a modified Gibbs-Thomson condition that is coupled to a slow evolution equation for the lamellar spacing. This formulation provides additional physical insights into the nature of the instability and a simple means to calculate an approximate stability spectrum. Finally, we investigate the influence of the ternary impurity on a short wavelength oscillatory instability that is already present at off-eutectic compositions in binary eutectics.Comment: 26 pages RevTex, 14 figures (28 EPS files); some minor changes; references adde

Pattern Stability and Trijunction Motion in Eutectic Solidification

We demonstrate by both experiments and phase-field simulations that lamellar eutectic growth can be stable for a wide range of spacings below the point of minimum undercooling at low velocity, contrary to what is predicted by existing stability analyses. This overstabilization can be explained by relaxing Cahn's assumption that lamellae grow locally normal to the eutectic interface.Comment: 4 pages, 5 eps figure

Phase-field modeling of microstructural pattern formation during directional solidification of peritectic alloys without morphological instability

During the directional solidification of peritectic alloys, two stable solid phases (parent and peritectic) grow competitively into a metastable liquid phase of larger impurity content than either solid phase. When the parent or both solid phases are morphologically unstable, i.e., for a small temperature gradient/growth rate ratio ($G/v_p$), one solid phase usually outgrows and covers the other phase, leading to a cellular-dendritic array structure closely analogous to the one formed during monophase solidification of a dilute binary alloy. In contrast, when $G/v_p$ is large enough for both phases to be morphologically stable, the formation of the microstructurebecomes controlled by a subtle interplay between the nucleation and growth of the two solid phases. The structures that have been observed in this regime (in small samples where convection effect are suppressed) include alternate layers (bands) of the parent and peritectic phases perpendicular to the growth direction, which are formed by alternate nucleation and lateral spreading of one phase onto the other as proposed in a recent model [R. Trivedi, Metall. Mater. Trans. A 26, 1 (1995)], as well as partially filled bands (islands), where the peritectic phase does not fully cover the parent phase which grows continuously. We develop a phase-field model of peritectic solidification that incorporates nucleation processes in order to explore the formation of these structures. Simulations of this model shed light on the morphology transition from islands to bands, the dynamics of spreading of the peritectic phase on the parent phase following nucleation, which turns out to be characterized by a remarkably constant acceleration, and the types of growth morphology that one might expect to observe in large samples under purely diffusive growth conditions.Comment: Final version, minor revisions, 16 pages, 14 EPS figures, RevTe

Hubungan Life Style dengan Kejadian Hipertensi pada Usia Dewasa (20-44 Tahun) di Wilayah Kerja Puskesmas Puuwatu Kota Kendari Tahun 2017

Penyakit Tidak Menular (PTM) merupakan penyebab utama kematian di dunia, yang bertanggung jawab atas68% dari 56 juta kematian yang terjadi pada tahun 2012 (WHO, 2014). Hiper tensi merupakan yang menjadi salahsatu masalah kesehatan penting di seluruh dunia karena prevalensinya yang tinggi dan terus meningkat. Sertamengakibatkan kematian dengan jumlah 9,4 juta setiap tahunnya. Hipertensi bertanggung jawab sekitar 45%kematian akibat penyakit jantung iskemik dan 51% akibat stroke. Penelitian ini bertujuan untuk mengetahuiHubungan Life Style Dengan Kejadian Hipertensi Pada Usia Dewasa (20-44 Tahun) Di Wilayah Kerja PuskesmasPuuwatu Kota Kendari. Penelitian ini merupakan penelitian analitik dengan rancangan penelitian cross sectional.Penentuan sampel dalam penelitian ini menggunakan pendekatan simple random sampling. Uji statistikmenggunakan chi square dengan menggunakan SPSS. Sampel dalam penelitian ini adalah 58 responden.Pengumpulan data dengan menggunakan kuesioner dan pemeriksaan tekanan darah terhadap responden untukmengidentifikasi kejadian penyakit hipertensi. Hasil penelitian menunjukan bahwa faktor yang berhubungandengan kejadian hipertensi adalah kebiasaan minum kopi (p=0,012), Sedangkan faktor yang tidakberhubungan adalah kebiasaan merokok (p=0,666), pola makan (p=0,509), kualitas tidur (p=1,000) dan aktifitasfisik (p=0,293).Kata Kunci Life Style, Hipertensi, Usia Dewasa

Hubungan Pengetahuan, Teman Sebaya dan Status Ekonomi dengan Perilaku Ngelem pada Anak Jalanan di Kota Kendari Tahun 2016

Anak adalah aset bangsa dan bagian dari generasi muda yang berperan sangat strategis, yaitu sebagai pewaris(successor) bangsa, penerus cita-cita perjuangan bangsa, sekaligus sebagai potensi sumber daya manusia dalamperkembangan nasional. Anak jalanan merupakan kelompok yang rentan dalam melakukan perilaku berisikoterhadap kesehatan seperti perilaku ngelem. Tujuan penelitian ini adalah mengetahui hubungan pengetahuan,teman sebaya dan status ekonomi dengan perilaku ngelem pada anak jalanan di Kota Kendari tahun 2016.Jenis penelitian adalah survey analitik dengan rancangan cross sectional study. Populasi dalam penelitianadalah anak jalanan Kota Kendari dan sampel dalam penelitian ini adalah anak jalanan Kota Kendari sebanyak49 anak. Pengambilan sampel dilakukan dengan metode sampling jenuh. Analisis data menggunakan uji chisquare dengan tingkat kepercayaan 95% (α=0,05). Hasil penelitian menunjukkan bahwa 67,3% anak jalananmemiliki perilaku ngelem dengan uji statistik menunjukkan bahwa tidak terdapat hubungan antarapengetahuan (ρValue=0,826 > α) dengan perilaku ngelem pada anak jalanan, terdapat hubungan antara temansebaya (ρValue=0,001< α), dan status ekonomi (ρValue =0,025) dengan perilaku ngelem pada anak jalanan yangmemiliki kategori kekuatan hubungan sedang

Analisis Faktor Risiko Kejadian Tonsilitis Kronis pada Anak Usia 5-11 Tahun di Wilayah Kerja Puskesmas Puuwatu Kota Kendari Tahun 2017

Tonsillitis Kronis adalah peradangan tonsil yang menetap sebagai akibat infeksi akut atau subklinis yangberulang. Penelitian ini bertujuan untuk mengetahui faktor risiko hygiene mulut, paparan asap dan riwayat ISPAterhadap kejadian tonsillitis kronis pada anak usia 5-11 tahun di wilayah kerja Puskesmas Puuwatu Kota Kendaritahun 2017. Penelitian ini menggunakan rancangan penelitian analitik observasional menggunakan desain casecontrol dengan prosedur non matching. Sampel dalam penelitian ini 76 pasien tonsilitis kronis dengan jumlahsampel sebanyak 38 kasus dan 38 kontrol, pengambilan sampel menggunakan teknik purposive sampling.statistikmenggunakan uji Chi-squre pada tingkat kepercayaan 95% ( =0,05). Hasil penelitian ini menunjukkan bahwaterdapat faktor risiko yang bermakna terhadap kejadian tonsilitis kronis dengan paparan asap OR= 6,981 denganrentan nilai LL 2,534 dan UL 19,235 dan riwayat ISPA OR= 4,800 dengan rentan nila i LL 1,535 dan UL 15,007 padainterfal kepercayaan (CI) 95%. Sedangkan Hygiene Mulut dengan kejadian tonsilitis kronis pada pasien tonsilitiskronis bukan merupakan faktor risiko yang bermakna. Disarankan untuk penyebaran informasi kepada masyarakatkhususnya pada anak mengenai hygiene mulut, paparan asap dan riwayat ISPA yang mempengaruhi kejadianTonsilitis kronis