Charles Shank - Academia.edu (original) (raw)
Papers by Charles Shank
Springer Series in Chemical Physics, 1980
This work is subject to copynght. All rights are reserved, whether the whole or part of the mater... more This work is subject to copynght. All rights are reserved, whether the whole or part of the material concerned, specifically those of translation, reprinting, reuse of illustrations, broadcasting, reproduction photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. © by Springer•Verlag Berlin Heidelberg 1980 Softcover reprint of the hardcover 1st edition 1980 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.
Aps March Meeting Abstracts, Mar 1, 1996
Aps April Meeting Abstracts, Apr 1, 2005
Biophysical Journal, 2009
Ca 2þ. Because major components of the spasmoneme, the contractile organelle inside the stalk, ar... more Ca 2þ. Because major components of the spasmoneme, the contractile organelle inside the stalk, are EF-hand Ca 2þ-binding proteins including spasmin and centrin, the spasmonemal contraction is thought to be related to other centrin-based motility mechanisms. This study describes how stall force affects contractions of live Vorticella. To impede contractions, we applied hydrodynamic drag force to Vorticella in a microfluidic channel with Poiseuille flow of viscous PVP solution. This method enables controlling the stall force by changing flow rate and the viscosity of the solution. Cell dimension measurements show that the zooid is elongated by the flow in relaxed and contracted states keeping roughly constant volume. As the stall force increases, the end-to-end length of the contracted stalk increases while that of the relaxed stalk is almost constant, and maximum contraction speed decreases while contractions take longer time. Furthermore, the time lag in contraction commencement between the zooid and the stalk also increases. We measured time differences in movement start among polystyrene beads attached to the stalk, and they increase with increasing stall force. These increasing time lags imply that the stalk cannot contract until it develops force great enough to overcome the stall force. The stall force affects the relaxation of Vorticella because relaxations take longer time as the stall force increase and the extending stalk resumes its contraction after the stall force is removed. It seems that although the spasmoneme retains contractile force, the stall force extends the stalk.
Applied Physics Letters, 1975
![Research paper thumbnail of Femtosecond Dynamics of Excited-State Evolution in [Ru(bpy)3]2+](https://attachments.academia-assets.com/82636687/thumbnails/1.jpg)
](Science, 1997
Time-resolved absorption spectroscopy on the femtosecond time scale has been used to monitor the ... more Time-resolved absorption spectroscopy on the femtosecond time scale has been used to monitor the earliest events associated with excited-state relaxation in tris-(2,2′-bipyridine)ruthenium(II). The data reveal dynamics associated with the temporal evolution of the Franck-Condon state to the lowest energy excited state of this molecule. The process is essentially complete in ∼300 femtoseconds after the initial excitation. This result is discussed with regard to reformulating long-held notions about excited-state relaxation, as well as its implication for the importance of non-equilibrium excited-state processes in understanding and designing molecular-based electron transfer, artificial photosynthetic, and photovoltaic assemblies in which compounds of this class are currently playing a key role.
Physical Review Letters, 1974
An ellipsometer has been used with picosecond pulsesto measure the time evolution of optically ge... more An ellipsometer has been used with picosecond pulsesto measure the time evolution of optically generated plasmas in intrinsic Ge. By measuring the change in optical elliptic-ity of a weak probe beam following the absorption of an intense excitation pulse, the time ...
Designed to help define new scientific directions related to complex systems in order to create n... more Designed to help define new scientific directions related to complex systems in order to create new understanding about the nano world and complicated, multicomponent structures.
Le Journal de Physique Colloques
Optics Communications
ABSTRACT
The Journal of Physical Chemistry
International Quantum Electronics Conference
AIP Conference Proceedings
Scattering of femtosecond laser pulses off a low energy relativistic electron beam at 90° offers ... more Scattering of femtosecond laser pulses off a low energy relativistic electron beam at 90° offers the possibility to generate ultrashort X-ray pulses. Experiments are under preparation in the Beam Test Facility of the Center for Beam Physics at LBL to demonstrate the generation and detection of such pulses. The experiments involve a relativistic electron beam (tunable from 25-50 MeV) with a bunch length of 10 ps containing 1-2 nC, and an ultra short pulse (50-200 fs), high peak power (>~2 TW) 0.8 mum Ti:Al2O3 laser system. The electron beam, focused down to about a 50 mum waist size intersects the focused laser beam at 90°. The laser field acts as an electromagnetic undulator with strength K (quiver velocity of an electron normalized to the speed of light) for the relativistic electron beam, generating radiation up-shifted by 2 gamma2/(1+K2/2) and a pulse length given by the overlapped interaction length in time of the laser beam and the electron beam. Here gamma is the usual Lorentz factor. Wavelength tuning will be accomplished in the experiment by generating wiggler strengths on the order of one as well as by electron beam energy tuning. For a 50 MeV electron beam and a laser beam focused to an intensity on the order of 1016 W/cm2, we expect 105 photons at 0.4 A˚ (10% bandwidth) in a cone angle of 6 mrad in a 170 fs pulse.
Le Journal de Physique Colloques
The Energy Citations Database (ECD) provides access to historical and current research (1948 to t... more The Energy Citations Database (ECD) provides access to historical and current research (1948 to the present) from the Department of Energy (DOE) and predecessor agencies.
Springer Series in Chemical Physics, 1980
This work is subject to copynght. All rights are reserved, whether the whole or part of the mater... more This work is subject to copynght. All rights are reserved, whether the whole or part of the material concerned, specifically those of translation, reprinting, reuse of illustrations, broadcasting, reproduction photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. © by Springer•Verlag Berlin Heidelberg 1980 Softcover reprint of the hardcover 1st edition 1980 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.
Aps March Meeting Abstracts, Mar 1, 1996
Aps April Meeting Abstracts, Apr 1, 2005
Biophysical Journal, 2009
Ca 2þ. Because major components of the spasmoneme, the contractile organelle inside the stalk, ar... more Ca 2þ. Because major components of the spasmoneme, the contractile organelle inside the stalk, are EF-hand Ca 2þ-binding proteins including spasmin and centrin, the spasmonemal contraction is thought to be related to other centrin-based motility mechanisms. This study describes how stall force affects contractions of live Vorticella. To impede contractions, we applied hydrodynamic drag force to Vorticella in a microfluidic channel with Poiseuille flow of viscous PVP solution. This method enables controlling the stall force by changing flow rate and the viscosity of the solution. Cell dimension measurements show that the zooid is elongated by the flow in relaxed and contracted states keeping roughly constant volume. As the stall force increases, the end-to-end length of the contracted stalk increases while that of the relaxed stalk is almost constant, and maximum contraction speed decreases while contractions take longer time. Furthermore, the time lag in contraction commencement between the zooid and the stalk also increases. We measured time differences in movement start among polystyrene beads attached to the stalk, and they increase with increasing stall force. These increasing time lags imply that the stalk cannot contract until it develops force great enough to overcome the stall force. The stall force affects the relaxation of Vorticella because relaxations take longer time as the stall force increase and the extending stalk resumes its contraction after the stall force is removed. It seems that although the spasmoneme retains contractile force, the stall force extends the stalk.
Applied Physics Letters, 1975
Science, 1997
Time-resolved absorption spectroscopy on the femtosecond time scale has been used to monitor the ... more Time-resolved absorption spectroscopy on the femtosecond time scale has been used to monitor the earliest events associated with excited-state relaxation in tris-(2,2′-bipyridine)ruthenium(II). The data reveal dynamics associated with the temporal evolution of the Franck-Condon state to the lowest energy excited state of this molecule. The process is essentially complete in ∼300 femtoseconds after the initial excitation. This result is discussed with regard to reformulating long-held notions about excited-state relaxation, as well as its implication for the importance of non-equilibrium excited-state processes in understanding and designing molecular-based electron transfer, artificial photosynthetic, and photovoltaic assemblies in which compounds of this class are currently playing a key role.
Physical Review Letters, 1974
An ellipsometer has been used with picosecond pulsesto measure the time evolution of optically ge... more An ellipsometer has been used with picosecond pulsesto measure the time evolution of optically generated plasmas in intrinsic Ge. By measuring the change in optical elliptic-ity of a weak probe beam following the absorption of an intense excitation pulse, the time ...
Designed to help define new scientific directions related to complex systems in order to create n... more Designed to help define new scientific directions related to complex systems in order to create new understanding about the nano world and complicated, multicomponent structures.
Le Journal de Physique Colloques
Optics Communications
ABSTRACT
The Journal of Physical Chemistry
International Quantum Electronics Conference
AIP Conference Proceedings
Scattering of femtosecond laser pulses off a low energy relativistic electron beam at 90° offers ... more Scattering of femtosecond laser pulses off a low energy relativistic electron beam at 90° offers the possibility to generate ultrashort X-ray pulses. Experiments are under preparation in the Beam Test Facility of the Center for Beam Physics at LBL to demonstrate the generation and detection of such pulses. The experiments involve a relativistic electron beam (tunable from 25-50 MeV) with a bunch length of 10 ps containing 1-2 nC, and an ultra short pulse (50-200 fs), high peak power (>~2 TW) 0.8 mum Ti:Al2O3 laser system. The electron beam, focused down to about a 50 mum waist size intersects the focused laser beam at 90°. The laser field acts as an electromagnetic undulator with strength K (quiver velocity of an electron normalized to the speed of light) for the relativistic electron beam, generating radiation up-shifted by 2 gamma2/(1+K2/2) and a pulse length given by the overlapped interaction length in time of the laser beam and the electron beam. Here gamma is the usual Lorentz factor. Wavelength tuning will be accomplished in the experiment by generating wiggler strengths on the order of one as well as by electron beam energy tuning. For a 50 MeV electron beam and a laser beam focused to an intensity on the order of 1016 W/cm2, we expect 105 photons at 0.4 A˚ (10% bandwidth) in a cone angle of 6 mrad in a 170 fs pulse.
Le Journal de Physique Colloques
The Energy Citations Database (ECD) provides access to historical and current research (1948 to t... more The Energy Citations Database (ECD) provides access to historical and current research (1948 to the present) from the Department of Energy (DOE) and predecessor agencies.