The importance of better models in stochastic optimization

Standard stochastic optimization methods are brittle, sensitive to stepsize choices and other algorithmic parameters, and they exhibit instability outside of well-behaved families of objectives. To address these challenges, we investigate models for stochastic minimization and learning problems that exhibit better robustness to problem families and algorithmic parameters. With appropriately accurate models---which we call the aProx family---stochastic methods can be made stable, provably convergent and asymptotically optimal; even modeling that the objective is nonnegative is sufficient for this stability. We extend these results beyond convexity to weakly convex objectives, which include compositions of convex losses with smooth functions common in modern machine learning applications. We highlight the importance of robustness and accurate modeling with a careful experimental evaluation of convergence time and algorithm sensitivity

Efficient Linear Programming Decoding of HDPC Codes

We propose several improvements for Linear Programming (LP) decoding algorithms for High Density Parity Check (HDPC) codes. First, we use the automorphism groups of a code to create parity check matrix diversity and to generate valid cuts from redundant parity checks. Second, we propose an efficient mixed integer decoder utilizing the branch and bound method. We further enhance the proposed decoders by removing inactive constraints and by adapting the parity check matrix prior to decoding according to the channel observations. Based on simulation results the proposed decoders achieve near-ML performance with reasonable complexity.Comment: Submitted to the IEEE Transactions on Communications, November 200

Pengaruh Pemberian Latihan Soal Terstruktur Setelah Pembelajaran Langsung Terhadap Pemahaman Konsep Ikatan Ion Pada Siswa Kelas X IPA SMA Negeri 4 Palangka Raya Tahun Ajaran 2018/2019

Penelitian ini bertujuan untuk mendeskripsikan pengaruh pemberian latihan soal terstruktur setelah pembelajaran langsung terhadap pemahaman konsep Ikatan ion pada siswa kelas X IPA SMA Negeri 4 Palangka Raya tahun ajaran 2018/2019. Penelitian ini merupakan penelitian eksperimen dengan desain penelitian non ekuivalen pretest-posttest control group design dan melibatkan sebanyak 72 siswa dari dua kelas X IPA SMA Negeri 4 Palangka Raya sebagai sampel yang ditentukan dengan teknik cluster random sampling, yaitu siswa kelas X IPA-2 (kelas eksperimen) sebanyak 36 orang siswa dan siswa kelas X IPA-4 (kelas kontrol) sebanyak 36 orang siswa. Instrumen yang digunakan berupa soal tes pemahaman konsep (tes I dan tes II), latihan soal terstruktur, dan latihan soal tak terstruktur. Data tes I diperoleh setelah pembelajaran langsung dan data tes II diperoleh setelah pembelajaran menggunakan latihan soal terstruktur dan latihan soal tak terstruktur. Hasil penelitian menunjukkan bahwa “pemberian latihan soal terstruktur berpengaruh terhadap pemahaman konsep siswa tentang ikatan ion setelah pembelajaran langsung pada siswa kelas X IPA SMA Negeri 4 Palangka Raya Tahun Ajaran 2018/2019”

THE DEGREE OF QUALIFYING STUDENTS TO APPLY THE PRINCIPLES OF COMPREHENSIVE QUALITY DURING THEIR PERIOD OF FIELD TRAINING

This study aims to identify the extent of qualifying field training students to apply the principles of comprehensive quality during their practical training period. (56) students were chosen deliberately, and to achieve the objectives of the study, the researcher used a questionnaire as a tool to collect data consisted of (40) paragraphs distributed over four areas: the field of quality in classroom management, the field of quality in the teaching methods used, the field of quality in the development of the learner’s scientific qualities. The researcher recommended the necessity of holding courses and workshops for students of physical education to clarify the concepts of comprehensive quality in the educational and teaching process, in addition to supervision and continuous evaluation of field training students so as to ensure the extent to which they apply the principles of total quality during their practical training.  Article visualizations

Pengaruh Pemberian Latihan Soal Terstruktur Setelah Pembelajaran Langsung terhadap Pemahaman Konsep Ikatan Ion pada Siswa Kelas X IPA SMA Negeri 4 Palangka Raya Tahun Ajaran 2018/2019

Penelitian ini bertujuan untuk mendeskripsikan pengaruh pemberian latihan soal terstruktur setelah pembelajaran langsung terhadap pemahaman konsep Ikatan ion pada siswa kelas X IPA SMA Negeri 4 Palangka Raya tahun ajaran 2018/2019. Penelitian ini merupakan penelitian eksperimen dengan desain penelitian non ekuivalen pretest-posttest control group design dan melibatkan sebanyak 72 siswa dari dua kelas X IPA SMA Negeri 4 Palangka Raya sebagai sampel yang ditentukan dengan teknik cluster random sampling, yaitu siswa kelas X IPA-2 (kelas eksperimen) sebanyak 36 orang siswa dan siswa kelas X IPA-4 (kelas kontrol) sebanyak 36 orang siswa. Instrumen yang digunakan berupa soal tes pemahaman konsep (tes I dan tes II), latihan soal terstruktur, dan latihan soal tak terstruktur. Data tes I diperoleh setelah pembelajaran langsung dan data tes II diperoleh setelah pembelajaran menggunakan latihan soal terstruktur dan latihan soal tak terstruktur. Hasil penelitian menunjukkan bahwa “pemberian latihan soal terstruktur berpengaruh terhadap pemahaman konsep siswa tentang ikatan ion setelah pembelajaran langsung pada siswa kelas X IPA SMA Negeri 4 Palangka Raya Tahun Ajaran 2018/2019”

Routine donor tomography in the eye bank as a sterile screening method for improved graft selection in corneal transplantation

Purpose: To evaluate the efficiency of using anterior segment optical coherence tomography (AS-OCT) (CASIA2) as a non-invasive and sterile screening method in the eye bank to detect corneal grafts with curvature and/or thickness abnormalities, thus improving the graft selection for corneal transplantation. Methods: Two hundred donor corneal tissues mounted in sterile tissue cultivation flasks were imaged using AS-OCT (CASIA 2). The corneal tissues were preserved at least 24 hours in medium 2 (6% dextran T-500) before the measurement. All images were grabbed through the posterior surface of the corneal tissues within a 7 mm central zone to create 3D volume data. The volume data set was imported to MATLAB and, after preprocessing the data and defining the region of interest (ROI), the edge of the front and back surfaces of the corneal tissues was detected. Subsequently, the adaptation of a sphero-cylindrical surface model with raytracing was carried out. The radii of curvature for the front and back surfaces and the central corneal thickness were determined according to the method proposed by Mäurer S., Eppig T., and Langenbucher A. at the Institute of Experimental Ophthalmology, Homburg/Saar. Results: The mean steep/flat front surface radius was 7.5 ± 0.24 (6.6-7.9) / 7.7 ± 0.22 (7.1-8.8) mm, the corresponding values for the back surface being 6.6 ± 0.22 (5.9-7.1) / 6.8 ± 0.21 (6.2-7.5) mm and the mean central thickness was 582 ± 45.1 (453-693) μm. Abnormalities (beyond ± 2 SD) were found in 13 corneas (6.5%) for anterior surface curvature, 15 for corneas (7.5%) for the posterior surface, and five corneas (2.5%) for thickness. Conclusions: The AS-OCT provides an objective and sterile. In addition, it may allow, in the future, a semi-automated screening method to identify corneal morphological and refractive alterations (e.g., keratoconus, status post PRK/LASIK) to further optimize corneal donor selection in eye banks.Ziel: Bewertung der Effizienz der optischen Kohärenztomographie des vorderen Augenabschnitts (AS-OCT) (CASIA2) als nicht-invasive und sterile Screeningsmethode in der Hornhautbank zur Erkennung von Hornhauttransplantaten mit Krümmungs- und/oder Dickenanomalien, wodurch die Transplantatauswahl für die Hornhauttransplantation verbessert werden sollte. Methoden: 200 Spenderhornhautgewebe wurden im sterilen Gewebekultivierungsbehälter vermessen. Die Hornhautgewebe wurden mindestens 24 Stunden vor der Messung in Medium 2 (mit 6% Dextran T-500) konserviert. Alle Bilder wurden durch die hintere Oberfläche der Hornhautgewebe innerhalb einer zentralen Zone von 7 mm aufgenommen, um 3D-Volumendaten zu erstellen. Der Volumendatensatz wurde in MATLAB importiert, und nach der Vorverarbeitung der Daten und der Definition der “Region of interest“ (ROI) wurde die Kante der Vorder- und Rückseite der Hornhautgewebe detektiert. Anschließend erfolgte die Anpassung eines sphärozylinderförmigen Oberflächenmodells mittels Raytracing. Die Krümmungsradien für Vorder- und Rückseite sowie die Dicke der zentralen Hornhaut wurden nach der von Mäurer S, Eppig T und Langenbucher A (Institut für Experimentelle Ophthalmologie, Homburg/Saar) vorgeschlagenen Methode bestimmt. Ergebnisse: Der mittlere steile / flache Radius der Vorderfläche betrug 7,5 ± 0,24 (6,6-7,9) / 7,7 ± 0,22 (7,1-8,8) mm, die entsprechenden Werte für die Rückfläche betrugen 6,6 ± 0,22 (5,9-7,1) / 6,8 ± 0,21 (6,2-7,5) mm und die mittlere zentrale Dicke betrug 582 ± 45,1 (453-693) μm. Anomalien (außerhalb ± 2 SD) wurden bei 13 Hornhäuten (6,5%) für die Krümmung der Vorderfläche, bei 15 Hornhäuten (7,5%) für die Krümmung der hinteren Oberfläche und bei 5 Hornhäuten (2,5%) für die zentrale Dicke gefunden. Schlussfolgerungen: Das Vorderabschnittes-OCT bietet eine objektive, sterile und zukünftig halbautomatisches Screening-Methode zur Identifizierung morphologischer und refraktiver Veränderungen der Hornhaut (z. B. Keratokonus, Status nach PRK/LASIK), um die Hornhautspenderauswahl in der Hornhautbank weiter zu optimieren

Is Conflict a Factor in a Population\u27s Quality of Life? A Comparative Study of University Students in the Palestinian Territories and Jordan

As nearly one third of the world\u27s population lives in an area that is in some way touched by war, researchers have long been interested in the varied impacts of conflict on civilians. Many indicators, measuring both physical and mental constructs, have been assessed in war-torn populations from around the world, one of which is health-related quality of life (HRQoL). The occupied Palestinian Territories (oPt) are one region in which copious research on health indicators has been undertaken in an effort to understand how long-term conflict manifests itself in noncombatant populations. However, existing studies focus primarily on indicators within the Palestinian population itself that impact HRQoL, and not on the extent to which the presence of the conflict and its consequences disturb physical and mental health outcomes compared to areas without conflict. The purpose of this study is to evaluate the impact of long-term conflict by comparing HRQoL in the oPt and the neighboring country of Jordan, as well as to assess how demographic factors such as socioeconomic status and household size can moderate or aggravate this impact. The potential mediating factors of insecurity and perceived stress will also be assessed. This study found that the presence of conflict was not the most significant predictor of low HRQoL. The mitigating factor of a traditional foundation of mental resilience in Palestinian culture is addressed as a potential explanation for this result. The implications of this study are wide-ranging, particularly in their ability to contribute to healthcare policy recommendations in war-affected areas, and to bolster our understanding of the health status and needs of those living in these areas

Penerapan Metode Drill Pada Pembelajaran Seni Budaya Untuk Meningkatkan Aktivitas Belajar Pada Siswa Kelas X di SMK YPSEI Palangka Raya

Penelitian ini bertujuan untuk mendeskripsikan Penerapan Metode drill Dalam Pembelajaran Seni Budaya Untuk Meningkatkan Aktivitas Belajar Pada Siswa Kelas X SMK YPSEI Palangka Raya pada tahun ajaran 2019/2020 yang berjumlah 17 siswa namun, terdapat 3 subjek penelitian yang tidak masuk sampel penelitian. Metode pada Penelitian ini adalah kuantitatif deskriptif yang dimana peneliti mendeskripsikan peningkatan aktivitas belajar siswa dalam pembelajaran seni budaya. Peneliti menggunakan pre-test sebagai instrumen penilaian pada pengetahuan siswa tentang pembelajaran tari yang berjumlah 30 butir soal. Peneliti juga menerapkan instrumen praktik sebagai pengganti post test. Terdapat 3 indikator penilaian yaitu unsur tari, properti dan kategori kepenarian. Berdasarkan hasil penelitian dengan menggunakan 3 siklus, maka dapat ditarik kesimpulan sebagai berikut: hasil pre-test tentang penguasaan materi seni tari pada siklus 1 rata-rata 66.8 meningkat pada siklus 2 dengan rata-rata nilai 72.44, pada siklus 3 meningkat menjadi rata-rata nilai 81,53. Jumlah siswa tuntas pada siklus 1 sebanyak 5 orang dengan persentase ketuntasan 50% kategori (belum berhasil), siklus 2 sebanyak 7 orang dengan persentase ketuntasan 65% kategori (cukup), pada siklus 3 meningkat jumlah siswa tuntas sebanyak 13 orang dengan persentase ketuntasan 85%  kategori (berhasil). Karena siklus 3 menghasilkan peningkatan nilai maka, dapat dikategorikan penerapan metode drill berhasil. Peneliti memberi saran kepada guru untuk mengarahkan siswa agar lebih aktif dan berkonsentrasi dalam kegiatan pembelajaran seni tari serta memberikan motivasi dan inovasi agar siswa lebih tertarik mengenal secara langsung (praktek) pembelajaran