Effect of Tendon Vibration on Hemiparetic Arm Stability in Unstable Workspaces

Sensory stimulation of wrist musculature can enhance stability in the proximal arm and may be a useful therapy aimed at improving arm control post-stroke. Specifically, our prior research indicates tendon vibration can enhance stability during point-to-point arm movements and in tracking tasks. The goal of the present study was to investigate the influence of forearm tendon vibration on endpoint stability, measured at the hand, immediately following forward arm movements in an unstable environment. Both proximal and distal workspaces were tested. Ten hemiparetic stroke subjects and 5 healthy controls made forward arm movements while grasping the handle of a two-joint robotic arm. At the end of each movement, the robot applied destabilizing forces. During some trials, 70 Hz vibration was applied to the forearm flexor muscle tendons. 70 Hz was used as the stimulus frequency as it lies within the range of optimal frequencies that activate the muscle spindles at the highest response rate. Endpoint position, velocity, muscle activity and grip force data were compared before, during and after vibration. Stability at the endpoint was quantified as the magnitude of oscillation about the target position, calculated from the power of the tangential velocity data. Prior to vibration, subjects produced unstable, oscillating hand movements about the target location due to the applied force field. Stability increased during vibration, as evidenced by decreased oscillation in hand tangential velocity

Analisis Kerusakan Terumbu Karang Akibat Sampah di Pulau Panggang, Kabupaten Kepulauan Seribu

Terumbu karang merupakan potensi pariwisata bagi pulau kecil namun menjadi terancam karena keberadaan sampah khususnya di Pulau Panggang. Tujuan diadakan penelitian untuk mengetahui sebaran terumbu karang dan sampah serta mengetahui pengaruh sampah pada terumbu karang dan tingkat kerusakannya. Penelitian dilakukan dengan metode survey terumbu karang dan pengukuran sampah. Survey terumbu karang menggunakan metode Line Intercept Transect. Pengukuran sampah dilakukan dengan pengukuran luasan sampah yang berada di pinggir pantai. Hasil berupa peta keberadaan sampah dan keadaan terumbu karang memperlihatkan lebih jelas adanya pengaruh dan kesinambungan pengaruh sampah pada terumbu karang dari sisi keruangan. Pengaruh sampah pada terumbu karang terlihat jelas pada wilayah timur laut. Jumlah luasan sampah pada wilayah Timur Laut mencapai 437 m². Luasan sampah wilayah ini merupakan luasan sampah tertinggi dibanding wilayah lainnya. Hasil persentase terumbu karang mati tertinggi pun juga di wilayah Timur Laut yaitu mencapai 71,9%. Aktivitas manusia yang sangat rendah serta tidak terdapatnya biota yang dapat mematikan terumbu karang menjadikan faktor lain yang dapat mematikan terumbu karang semakin sedikit. Wilayah ini dapat meyakinkan bahwa keberadaan sampah mempengaruhi terumbu karang

¬MPPT pada Sistem PV Menggunakan Algoritma Firefly dan Modified P&O dengan Konverter Hybrid Cuk Terkoneksi ke Grid Satu Phasa di Bawah Kondisi Partial Shaded

— Photovoltaic (PV) merupakan sumber energi terbarukan yang paling banyak dijumpai di alam serta merupakn energi alternatif yang sangat pesat perkembangannya. Untuk mengahasilkan daya, sebuah PV dipengaruhi sebuah nilai intensitas cahaya matahari yang mengenainya. Sebuah sistem PV membutuhkan sebuah kontrol yang bertujuan untuk meningkatkan efisien daya PV tersebut. Kontrol ini adalah Maximum Power Point Tracking (MPPT) yang dapat mengoptimalkan daya yang dihasilkan oleh PV. Sebuah PV hanya menghasilkan nilai tegangan yang rendah, untuk itu perlu menggunakan koverter DC-DC step up untuk menaikan rasio tegangan DC tadi. Untuk mengoptimalkan sistem ini, diperlukan sebuah konverter yang efisien dan dapat menghasilkan rasio konversi tegangan yang tinggi. Pada penelitian menggunakan firefly algorithm (FFA) dan modified perturb and observe (P&O) sebagai MPPT untuk mendapatkan nilai daya optimal pada keluaran PV. Konverter DC-DC yang digunakan adalah hybrid cuk converter boost mode yang memiliki rasio tegangan yang tinggi. Dari DC-link kemudian masuk ke inverter (VSI) yang diinterkoneksi dengan grid menggunakan current control. Hasil analisis simulasi menunjukan bahwa FFA dan P&O mampu menghasilkan daya PV yang optimum dengan riak yang kecil dan konverter hybrid cuk converter boost mode dapat menghasilkan rasio tegangan yang lebih besar dibandingkan konverter cuk biasa. Kata Kunci — PV, MPPT FFA, MPPT P&O, Hybrid Cuk Converter, DC-Link, Inverter Grid Connecte

Analysis of the temperatures measured in very thick and insulating roofs in the vicinity of a chimney

Chimneys convey exhaust gas produced in domestic heat appliances to the external environment and to do this they have to pass through elements such as roofs and floors. If these elements are made up of flammable materials the fire hazard may occur. In some European countries the number of roof fire is very high and they affect also certified chimneys, that is, tested following the prescription of the related standards. The aim of this paper is to highlight that the certification procedure does not allow to test chimneys in the worst condition, therefore, chimney installed following the manufacturer prescriptions may in some cases cause the overheating and subsequent roof fire. To do this, experimental tests have been performed for measuring the temperature on roofs in the vicinity of a certified chimney. The results show that the certification procedure should be revised

Suppression of HBV by Tenofovir in HBV/HIV coinfected patients : a systematic review and meta-analysis

Background: Hepatitis B coinfection is common in HIV-positive individuals and as antiretroviral therapy has made death due to AIDS less common, hepatitis has become increasingly important. Several drugs are available to treat hepatitis B. The most potent and the one with the lowest risk of resistance appears to be tenofovir (TDF). However there are several questions that remain unanswered regarding the use of TDF, including the proportion of patients that achieves suppression of HBV viral load and over what time, whether suppression is durable and whether prior treatment with other HBV-active drugs such as lamivudine, compromises the efficacy of TDF due to possible selection of resistant HBV strains. Methods: A systematic review and meta-analysis following PRISMA guidelines and using multilevel mixed effects logistic regression, stratified by prior and/or concomitant use of lamivudine and/or emtricitabine. Results: Data was available from 23 studies including 550 HBV/HIV coinfected patients treated with TDF. Follow up was for up to seven years but to ensure sufficient power the data analyses were limited to three years. The overall proportion achieving suppression of HBV replication was 57.4%, 79.0% and 85.6% at one, two and three years, respectively. No effect of prior or concomitant 3TC/FTC was shown. Virological rebound on TDF treatment was rare. Interpretation: TDF suppresses HBV to undetectable levels in the majority of HBV/HIV coinfected patients with the proportion fully suppressed continuing to increase during continuous treatment. Prior treatment with 3TC/FTC does not compromise efficacy of TDF treatment. The use of combination treatment with 3TC/FTC offers no significant benefit over TDF alone