Open Access. Powered by Scholars. Published by Universities.®
- Discipline
Articles 1 - 6 of 6
Full-Text Articles in Physics
Forces At Individual Pseudopod-Filament Adhesive Contacts, Govind Paneru, Prem S. Thapa, Sean P. Mcbride, David Moore-Nichols, Bruce M. Law, Bret N. Flanders
Forces At Individual Pseudopod-Filament Adhesive Contacts, Govind Paneru, Prem S. Thapa, Sean P. Mcbride, David Moore-Nichols, Bruce M. Law, Bret N. Flanders
Physics Faculty Research
On-chip cellular force sensors are fabricated from cantilever poly(3,4-ethylene dioxythiophene) filaments that visibly deflect under forces exerted at individual pseudopod-filament adhesive contacts. The shape of the deflected filaments and their ∼3 nN/μm spring constants are predicted by cantilever rod theory. Pulling forces exerted by Dictyostelium discoideumcells at these contacts are observed to reach ∼20 nN without breaking the contact.
Characteristic Extraction Tool For Gravitational Waveforms, Maria C. Babiuc-Hamilton, B´Ela Szila´Gyi, Jeffrey Winicour, Yosef Zlochower
Characteristic Extraction Tool For Gravitational Waveforms, Maria C. Babiuc-Hamilton, B´Ela Szila´Gyi, Jeffrey Winicour, Yosef Zlochower
Physics Faculty Research
We develop and calibrate a characteristic waveform extraction tool whose major improvements and corrections of prior versions allow satisfaction of the accuracy standards required for advanced LIGO data analysis. The extraction tool uses a characteristic evolution code to propagate numerical data on an inner worldtube supplied by a 3+1 Cauchy evolution to obtain the gravitational waveform at null infinity. With the new extraction tool, high accuracy and convergence of the numerical error can be demonstrated for an inspiral and merger of mass M binary black holes even for an extraction worldtube radius as small as R=20M. The …
High Gravitational Waveform Accuracy At Null Infinity, Maria Babiuc-Hamilton
High Gravitational Waveform Accuracy At Null Infinity, Maria Babiuc-Hamilton
Physics Faculty Research
The aim of Cauchy-characteristic extraction is to provide a standardized waveform extraction tool for the numerical relativity community. The new extraction tool contains major improvements and corrections to previous versions and displays convergence. The error introduced by CCE satisfies the time domain criteria required for advanced LIGO data analysis. The importance of accurate waveforms to the gravitational wave astronomy has created an urgency for tools like CCE. The source code has been released to the public and is available as part of the Einstein Toolkit. We welcome applications to a variety of generic Cauchy codes implementing Einstein Equations of General …
Towards A Standardized Characteristic Extraction Tool, Maria Babiuc-Hamilton
Towards A Standardized Characteristic Extraction Tool, Maria Babiuc-Hamilton
Physics Faculty Research
Knowing the precise details of the gravitational wave signature obtained from numerical simulations of binary black hole mergers is a key requirement for meaningful detection and scientific interpretation of the data. However, the waveforms are not easy to be accurately computed. The importance of this problem to the future of gravitational wave astronomy is well recognized. Cauchy-Characteristic Extraction (CCE) is the most precise and refined extraction method available. The CCE technique connects the strong-field Cauchy evolution of the spacetime near the merger to the characteristic evolution to future null infinity where the waveform is extracted in an unambiguous way. Recently, …
Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, H-J. L. Gossmann
Superlattice Ultrasonic Generation, Thomas E. Wilson, M. Oehme, E. Kasper, H-J. L. Gossmann
Physics Faculty Research
We report the first experimental evidence for the resonant excitation of coherent high-frequency acoustic phonons in semiconducting doping superstructures by far-infrared laser radiation. After a grating-coupled delta-doped silicon doping superlattice is illuminated with ~1 kW/mm2 nanosecond-pulsed 246 GHz laser radiation, a delayed nanosecond pulse is detected by a superconducting bolometer at a time corresponding to the appropriate time-of-flight for ballistic longitudinal acoustic phonons across the (100) silicon substrate. The absorbed phonon power density in the microbolometer is observed to be ~10 μW/mm2, in agreement with theory. The phonon pulse duration also matches the laser pulse duration. The …
Evidence For The Generation Of Coherent Longitudinal Acoustic Phonons Through The Resonant Absorption Of Pulsed Far-Infrared Laser Radiation In Silicon Doping Superlattices, Thomas E. Wilson
Physics Faculty Research
We report the first experimental evidence for the direct excitation of coherent high-frequency acoustic phonons in semiconducting doping superstructures by electromagnetic fields of the same frequency. Nanosecond pulses of acoustic phonons have been detected by a superconducting bolometer at the appropriate time-of-flight across a (100) silicon substrate for ballistic longitudinal phonons when a silicon doping superlattice is illuminated with grating-coupled nanosecond-pulsed 246-GHz laser radiation with power density of ∼1 kW/mm2. The absorbed phonon power density in the microbolometer is estimated to be ∼ 10/Wmm2, in agreement with theory. The phonon pulse duration matches the laser pulse …