Analisis Potensi Longsor Pada Lereng Galian Penambangan Timah (Studi Kasus Area Penambangan Timah Di Jelitik, Kabupaten Bangka)

Akibat kegiatan penambangan Timah terbentuklah sebuah lereng galian. Lereng denganstrukturtanah dan kemiringan tertentu menimbulkan potensi longsor yang membahayakankeselamatan pekerja tambang. Oleh karenanya dilakukan analisis potensi kelongsoranpada lereng galian penambangan Timah tersebut dengan melihat faktor keamanan (SF)lereng, serta menganalisis sejauh mana pergerakan tanah (deformasi) akibat penggalian.Analisis dilakukan dengan memodelkan lereng galian menggunakan program Plaxis 2D-Versi 8, berdasarkan data primer dan studi parametrik. Data yang diperlukan yaitu tinggilereng (H), stratigrafi, sudut kemiringan lereng (α), berat volume tanah (γ), koevisienpermeabilitas (k), modulus elastisitas tanah (E), angka poisson (v), kohesi tanah (c), sudutgeser tanah (ϕ) dan asumsi muka air tanah. Selain itu dilakukan juga simulasi perbaikanlereng dengan mengubah geometri asli lereng berdasarkan dua alternatif solusi perbaikanyaitu dengan memperkecil sudut kemiringan lereng dan membuat berm/trap pada lereng.Hasil analisis kelongsoran pada lereng galian penambangan Timah mendapatkan faktorkeamanan (SF) sebesar 1,18 sehingga lereng teridentifikasi pada kondisi keruntuhanpernah terjadi artinya lereng berpotensi longsor. Adapun deformasi yang terjadi sebesar31,01*10-3 meter, artinya akibat penggalian memungkinkan massa tanah bergarak sejauh31,01*10-3 meter sebelum terjadi keruntuhan sempurna. Dari dua alternatif analisisperbaikan yang direkondasikan, solusi terbaik didapatkan dengan membuat berm/trapsebanyak 6 berm dengan sudut kemiringan pada setiap berm sebesar 50ᵒ dan lebar antarberm sebesar 3 meter. SF yang disapatkan sebesar 2,56 mengalami peningkatan sebesar116,96 %, dengan deformasi sebesar 17,71*10-3 meter, mengalami pengecilan sebesar42,89 %. Karena penggalian tetap mengalami pergerakan massa tanah (deformasi), tetapiberdasarkan analisis faktor keamanan, lereng pada kondisi aman (tidak berpotensilongsor).Kata kunci : Lereng galian, potensi kelongsoran, solusi perbaikan lereng

Unexpected Features of Supersymmetry with Central Charges

It is shown that N=2 supersymmetric theories with central charges present some hidden quartic symmetry. This enables us to construct representations of the quartic structure induced by superalgebra representations.Comment: 14 pages, more details have been given, to appear in J. Phys.

Optimal control for halo orbit missions

This paper addresses the computation of the required trajectory correction maneuvers (TCM) for a halo orbit space mission to compensate for the launch velocity errors introduced by inaccuracies of the launch vehicle. By combiningdynamical systems theory with optimal control techniques, we produce a portrait of the complex landscape of the trajectory design space. This approach enables parametric studies not available to mission designers a few years ago, such as how the magnitude of the errors and the timingof the first TCM affect the correction ΔV. The impetus for combiningdynamical systems theory and optimal control in this problem arises from design issues for the Genesis Discovery mission being developed for NASA by the Jet Propulsion Laboratory

Design of the Spitzer Space Telescope Heritage Archive

It is predicted that Spitzer Space Telescope’s cryogen will run out in April 2009, and the final reprocessing for the cryogenic mission is scheduled to end in April 2011, at which time the Spitzer archive will be transferred to the NASA/IPAC Infrared Science Archive (IRSA) for long-term curation. The Spitzer Science Center (SSC) and IRSA are collaborating to design and deploy the Spitzer Heritage Archive (SHA), which will supersede the current Spitzer archive. It will initially contain the raw and final reprocessed cryogenic science products, and will eventually incorporate the final products from the Warm mission. The SHA will be accompanied by tools deemed necessary to extract the full science content of the archive and by comprehensive documentation

Pelatihan Penyusunan Penelitian Tindakan Kelas pada Guru Bahasa Indonesia dalam Upaya Peningkatan Kualitas Pembelajaran di Sekolah Menengah Atas Negeri 1 Labuapi

Kegiatan pengabdian pada masyarakat ini merupakan kegiatan yang dilakukan sebagai wujud pembinaan kepada masyarakat. Kegiatan pengabdian pada masyarakat ini terlaksana dalam bentuk pelatihan menyusun PTK (Penelitian Tindakan Kelas) bagi guru, khususnya Guru Bahasa Indonesia di Sekolah Menengah Atas Negeri 1 Labuapi Kabupaten Lombok Barat. Kegiatan ini dilaksanakan sebagai upaya peningkatan kualitas guru dalam pengembangan proses pembelajaran. Adapun hasil dari kegiatan ini yaitu; 1) penyampaian materi PTK, berisi tentang konsep dasar PTK, tujuan PTK, manfaat PTK, model-model PTK, fokus dan sasaran PTK, cara memilih dan merumuskan masalah PTK, langkah-langkah kegiatan PTK, cara menyusun instrumen PTK, cara menganalisis data penelitian jenis PTK, cara menyusun laporan PTK, artikel ilmiah, 2) menyusun rancangan PTK, 3) melaksanakan penelitian tindakan kelas, dan 4) menyusun artikel PTK. Para Guru Bahasa Indonesia yang menjadi peserta dalam kegiatan ini mampu menghasilkan artikel ilmiah yang dimuat pada jurnal nasional yang ber-ISSN

Defense responses of Hevea brasiliensis to elicitors from root rot fungi

L'élicitation de quelques réactions de défense du système racinaire de l'Hévéa (#Hevea brasiliensis) aux attaques du #Rigidoporus lignosus$ a été réalisée en injectant des extraits des parois fongiques dans les racines de jeunes plantes âgées de 1 mois. Une étude de la cinétique a révélé, au microscope optique, une induction de la lignification 3, 8, 15 et 45 jours après l'injection d'éliciteurs. Les résultats obtenus montrent que certaines réactions de défense des racines des plantes ligneuses peuvent être stimulées par des éliciteurs fongiques dans le but de renforcer les barrières structurales des tissus hôtes. (D'après résumé d'auteur

Influenza-like illness in acute myocardial infarction patients during the winter wave of the influenza A H1N1 pandemic in London: a case-control study.

OBJECTIVE: To investigate recent respiratory and influenza-like illnesses (ILIs) in acute myocardial infarction patients compared with patients hospitalised for acute non-vascular surgical conditions during the second wave of the 2009 influenza A H1N1 pandemic. DESIGN: Case-control study. SETTING: Coronary care unit, acute cardiology and acute surgical admission wards in a major teaching hospital in London, UK. PARTICIPANTS: 134 participants (70 cases and 64 controls) aged ≥40 years hospitalised for acute myocardial infarction and acute surgical conditions between 21 September 2009 and 28 February 2010, frequency-matched for gender, 5-year age-band and admission week. PRIMARY EXPOSURE: ILI (defined as feeling feverish with either a cough or sore throat) within the last month. SECONDARY EXPOSURES: Acute respiratory illness within the last month not meeting ILI criteria; nasopharyngeal and throat swab positive for influenza virus. RESULTS: 29 of 134 (21.6%) participants reported respiratory illness within the last month, of whom 13 (9.7%) had illnesses meeting ILI criteria. The most frequently reported category for timing of respiratory symptom onset was 8-14 days before admission (31% of illnesses). Cases were more likely than controls to report ILI-adjusted OR 3.17 (95% CI 0.61 to 16.47)-as well as other key respiratory symptoms, and were less likely to have received influenza vaccination-adjusted OR 0.46 (95% CI 0.19 to 1.12)-although the differences were not statistically significant. No swabs were positive for influenza virus. CONCLUSIONS: Point estimates suggested that recent ILI was more common in patients hospitalised with acute myocardial infarction than with acute surgical conditions during the second wave of the influenza A H1N1 pandemic, and influenza vaccination was associated with cardioprotection, although the findings were not statistically significant. The study was underpowered, partly because the age groups typically affected by acute myocardial infarction had low rates of infection with the pandemic influenza strain compared with seasonal influenza