Antiphase Synchronization in a Flagellar-Dominance Mutant of Chlamydomonas

Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report here the discovery that ptx1, a flagellar dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. Long-duration high-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wildtype. Possible mechanisms underlying these observations are discussed.Comment: 5 pages, 4 figure

PERBEDAAN METODE PEMBELAJARAN SIMULASI DAN DEMONSTRASI TERHADAP PENINGKATAN HASIL BELAJAR PESERTA DIDIK KELAS XI TITL

Penelitian ini bertujuan untuk :1) Untuk mengetahui pengaruh terhadap hasil belajar peserta didik kelas XI TITL SMK Negeri 1 Kupang Barat setelah menggunakan metode simulasi pada mata pelajaran Instalasi penerangan. 2) Untuk mengetahui pengaruh terhadap hasil belajar peserta didik kelas XI TITL SMK Negeri 1 Kupang Barat setelah menggunakan metode demonstrasi pada mata pelajaran Instalasi penerangan. 3) Untuk mengetahui perbedaan terhadap hasil belajar peserta didik kelas XI TITL SMK Negeri 1 Kupang Barat setelah menggunakan metode simulasi dan metode demonstrasi pada mata pelajaran Instalasi penerangan. Metode penelitian yang digunakan dalam penelitian ini yaitu metode Eksperimen. Teknik pengumpulan data yang digunakan dalam penelitian ini adalahdengan menggunakan teknik tes.Analisis data yang digunakan adalah uji persyaratan analisis dengan uji normalitas dan uji homogenitas serta uji hipotesisdengan analisis regresi sederhana dan uji independent t-test dengan bantuan Statistical Product and Service Solution ( SPSS ). Hasil penelitian menunjukkan bahwa metode simulasi Nilai rata-rata kelas simulasi sebesar 88,77 dan kelas demonstrasi 84,50. Selisih antara keduanya adalah 4,27. Maka dapat disimpulkan bahwarata-rata hasil belajar peserta didik yang menggunakan metode simulasi lebih tinggi dibanding ratarata hasil belajar peserta didik yang menggunakan metode demonstrasi. Hasil perhitungan uji hipotesistersebut diperoleh hasil sebagai berikut:thitung =-12,337 dan didapatkan nilai= 2.75639 dengan df = 60 karena thutng ˂ttabel(-12,337 ˂ 2.75639) dengan nilai signifikan < 0.005 (0.000 < 0.005) . thitung= -12,271 dandidapatkan nilai= 2.75639 dengan df = 60 karenathitung ˂ttabel(-12,271 ˂ 2.75639) dengan nilai signifikan < 0.005 (0.000 < 0.005)

Antiphase Synchronization in a Flagellar-Dominance Mutant of Chlamydomonas

This is the final version. Available on open access from American Physical Society via the DOI in this record. Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report the discovery that ptx1, a flagellar-dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. High-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wild-type. Possible mechanisms underlying these observations are discussed.Spanish Ministerio de Ciencia y InnovaciónEngineering and Physical Sciences Research Council (EPSRC)Biotechnology and Biological Sciences Research Council (BBSRC)European Research CouncilWellcome Trus

High-Power-Density Energy-Harvesting Devices Based on the Anomalous Nernst Effect of Co/Pt Magnetic Multilayers

The anomalous Nernst effect (ANE) is a thermomagnetic phenomenon with potential applications in thermal energy harvesting. While many recent works studied the approaches to increase the ANE coefficient of materials, relatively little effort was devoted to increasing the power supplied by the effect. Here, we demonstrate a nanofabricated device with record power density generated by the ANE. To accomplish this, we fabricate micrometer-sized devices in which the thermal gradient is 3 orders of magnitude higher than conventional macroscopic devices. In addition, we use Co/Pt multilayers, a system characterized by a high ANE thermopower (∼1 μV/K), low electrical resistivity, and perpendicular magnetic anisotropy. These innovations allow us to obtain power densities of around 13 ± 2 W/cm3. We believe that this design may find uses in harvesting wasted energy, e.g., in electronic devicesThis work was supported by the Spanish Ministry of Science and Innovation through the projects PID2019-108075RB-C31 and MCIN/FEDER RTI2018-097895-B-C41. G.L.-P. acknowledges financial support from the Spanish Ministry of Science and Innovation through the Juan de la Cierva program (FJCI-2017-32370). J.M.-M. acknowledges the Spanish Ministry of Science, Innovation and Universities through FPU Program No. FPU18/01738

Observation of Flux Reversal in a Symmetric Optical Thermal Ratchet

We demonstrate that a cycle of three holographic optical trapping patterns can implement a thermal ratchet for diffusing colloidal spheres, and that the ratchet-driven transport displays flux reversal as a function of the cycle frequency and the inter-trap separation. Unlike previously described ratchet models, the approach we describe involves three equivalent states, each of which is locally and globally spatially symmetric, with spatiotemporal symmetry being broken by the sequence of states.Comment: 4 pages, 2 figures, submitted for publication in Physical Review Letter

Antiphase synchronization in a flagellar-dominance mutant of Chlamydomonas

Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report the discovery that ptx1, a flagellar-dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. High-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wild-type. Possible mechanisms underlying these observations are discussed. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Support is acknowledged from the Spanish Ministerio de Ciencia y Innovación Grant No. FIS2010-22322-C01 and a Ramón y Cajal Fellowship (I. T.), an EPSRC postdoctoral Fellowship (M. P.), the BBSRC, the EPSRC, ERC Advanced Investigator Grant No. 247333, and a Senior Investigator Award from the Wellcome Trust (R. E. G.)Peer Reviewe

Dynamic critical behavior of the Chayes-Machta-Swendsen-Wang algorithm

We study the dynamic critical behavior of the Chayes-Machta dynamics for the Fortuin-Kasteleyn random-cluster model, which generalizes the Swendsen-Wang dynamics for the q-state Potts model to noninteger q, in two and three spatial dimensions, by Monte Carlo simulation. We show that the Li-Sokal bound z \ge \alpha/\nu is close to but probably not sharp in d=2, and is far from sharp in d=3, for all q. The conjecture z \ge \beta/\nu is false (for some values of q) in both d=2 and d=3.Comment: Revtex4, 4 pages including 4 figure

Magnetization Signature of Topological Surface States in a Non-Symmorphic Superconductor

Superconductors with nontrivial band structure topology represent a class of materials with unconventional and potentially useful properties. Recent years have seen much success in creating artificial hybrid structures exhibiting the main characteristics of 2D topological superconductors. Yet, bulk materials known to combine inherent superconductivity with nontrivial topology remain scarce, largely because distinguishing their central characteristic—the topological surface states—has proved challenging due to a dominant contribution from the superconducting bulk. In this work, a highly anomalous behavior of surface superconductivity in topologically nontrivial 3D superconductor In2Bi, where the surface states result from its nontrivial band structure, itself a consequence of the non-symmorphic crystal symmetry and strong spin–orbit coupling, is reported. In contrast to smoothly decreasing diamagnetic susceptibility above the bulk critical field, Hc2, as seen in conventional superconductors, a near-perfect, Meissner-like screening of low-frequency magnetic fields well above Hc2 is observed. The enhanced diamagnetism disappears at a new phase transition close to the critical field of surface superconductivity, Hc3. Using theoretical modeling, the anomalous screening is shown to be consistent with modification of surface superconductivity by the topological surface states. The possibility of detecting signatures of the surface states using macroscopic magnetization provides a new tool for the discovery and identification of topological superconductor

Magnetization Signature of Topological Surface States in a Non-Symmorphic Superconductor

Superconductors with nontrivial band structure topology represent a class of materials with unconventional and potentially useful properties. Recent years have seen much success in creating artificial hybrid structures exhibiting the main characteristics of 2D topological superconductors. Yet, bulk materials known to combine inherent superconductivity with nontrivial topology remain scarce, largely because distinguishing their central characteristic—the topological surface states—has proved challenging due to a dominant contribution from the superconducting bulk. In this work, a highly anomalous behavior of surface superconductivity in topologically nontrivial 3D superconductor In2Bi, where the surface states result from its nontrivial band structure, itself a consequence of the non-symmorphic crystal symmetry and strong spin–orbit coupling, is reported. In contrast to smoothly decreasing diamagnetic susceptibility above the bulk critical field, Hc2, as seen in conventional superconductors, a near-perfect, Meissner-like screening of low-frequency magnetic fields well above Hc2 is observed. The enhanced diamagnetism disappears at a new phase transition close to the critical field of surface superconductivity, Hc3. Using theoretical modeling, the anomalous screening is shown to be consistent with modification of surface superconductivity by the topological surface states. The possibility of detecting signatures of the surface states using macroscopic magnetization provides a new tool for the discovery and identification of topological superconductor