Statistical mechanics of geomagnetic orientation in sediment bacteria

Also published as: Biological Bulletin 159 (1980): 459-460Last year we reported on time-of-transit experiments in which magnetically orienting bacteria crossed a 1-mm stretch in the direction of a uniform magnetic field. The bacteria were found to behave as tiny self-propelled compass needles subject both to magnetic field alignment and to the randomizing effect of thermal agitation. In strong fields, magnetic bacteria are held in tight aligment; in weaker fields, their swimming paths meander more and transit times are greater. Paul Langevin derived an expression for the distribution of orientation in an ensemble of free-moving dipole particles as a function of ambient field strength. His theory becomes applicable to our experiments when bacterial migration is analyzed as a sequence of short steps during each of which the cell swims in a direction randomly selected from the Langevin distribution . The duration of each step, Δt, is actually a time constant of the cell's loss of directionality due to thermal agitation. By thus treating the migration as a process of random walk with drift, we are able to predict the mean and variance of the time of transit across a 1-mm stretch.Prepared for the Office of Naval Research under Contract N00014-79-C-0071

Aplikasi Telepon Seluler sebagai Sistem Kendali Jarak Jauh untuk Menyalakan dan Mematikan Mesin Sepeda Motor

Telepon seluler merupakan alat komunikasi. Selain sebagai alat komunikasi telepon seluler dapat juga digunakansebagai sistem pengendali jarak jauh, dalam hal ini dapat menyalakan dan mematikan mesin sepeda motor. Salahsatu manfaatnya adalah untuk memanaskan mesin sepeda motor yang ditinggalkan di garasi saat tidak ada orangdi rumah. Aplikasi pada sistem ini menggunakan handphone, mikropengendali ATmega 16, IC DTMF MT8870dan relai. Ketika mesin dinyalakan, parameter yang diamati adalah keberhasilan kinerja IC DTMF. Sedangkankondisi mematikan mesin sepeda motor parameter yang diamati adalah keberhasilan alat mengirimkan sinyalberupa speed dial yang digunakan sebagai laporan. Untuk mengaktifkan kontak dan menyalakan starter padasepeda motor digunakan tombol 1 dan tombol 2 pada keypad telepon seluler. Ketika dilakukan penekanantombol, IC DTMF MT8870 akan menerjemahkan sinyal DTMF yang dikirim dari telepon seluler pengendali.Sinyal yang dihasilkan kemudian akan diproses oleh ATMega 16 mikropengendali. Mesin akan mati secaraotomatis selama 120 detik setelah waktu yang ditentukan telah terlewati atau dengan melakukan penekanantombol selain tombol 2. Report yang dihasilkan setelah mesin panas berupa panggilan dari telepon seluler yangterpasang pada alat dengan memanfaatkan fungsi speed dial pada handphone

Systematic review of determinants of mortality in high frequency oscillatory ventilation in acute respiratory distress syndrome

INTRODUCTION: Mechanical ventilation has been shown to cause lung injury and to have a significant impact on mortality in acute respiratory distress syndrome. Theoretically, high frequency oscillatory ventilation seems an ideal lung protective ventilation mode. This review evaluates determinants of mortality during use of high frequency oscillatory ventilation. METHODS: PubMed was searched for literature reporting randomized trials and cohort studies of high frequency ventilation in adult patients with acute respiratory distress syndrome. Data on mortality and determinants were extracted for patients treated with high frequency oscillatory ventilation. Linear regression analyses were conducted to produce graphical representations of adjusted effects of determinants of mortality. RESULTS: Cohorts of patients treated with high frequency oscillatory ventilation from two randomized trials and seven observational studies were included. Data from cohorts comparing survivors with non-survivors showed differences in age (42.3 versus 51.2 years), prior time on conventional mechanical ventilation (4.0 versus 6.2 days), APACHE II score (22.4 versus 26.1), pH (7.33 versus 7.26) and oxygenation index (26 versus 34). Each extra day on conventional ventilation was associated with a 20% higher mortality adjusted for age and APACHE II score (relative risk (RR) 1.20, 95% confidence interval (CI) 1.15–1.25). However, this association was confounded by differences in pH (pH adjusted RR 1.03, 95% CI 0.73–1.46). Oxygenation index seemed to have an independent effect on mortality (RR 1.10, 95% CI 0.95–1.28). CONCLUSION: Prolonged ventilation on conventional mechanical ventilation prior to high frequency oscillatory ventilation was not related to mortality. Oxygenation index was a determinant of mortality independent of other disease severity markers