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Topic: Brownian motor

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	Brownian motor - Wikipedia, the free encyclopedia
		Brownian motors are nano-scale or molecular devices by which thermally activated processes (chemical reactions) are controlled and used to generate directed motion in space and to do mechanical or electrical work.
		The dynamics and activity of Brownian motors are current topics of study in theoretical and experimental biophysics.
		Brownian motors are sometimes modeled using the Fokker-Planck equation or with Monte Carlo methods.
	en.wikipedia.org /wiki/Brownian_motor (308 words)

	Brownian ratchet - Wikipedia, the free encyclopedia
		The Brownian ratchet is a thought experiment about an apparent perpetual motion machine postulated by Richard Feynman in a physics lecture at the California Institute of Technology on May 11, 1962 as an illustration of the laws of thermodynamics.
		The device consists of a gear with a ratchet, that vibrates under Brownian motion (hence the name) in a heat bath.
		Although the Brownian ratchet seems, at first sight, to extract useful work from Brownian motion, Feynman demonstrated through a number of detailed arguments that its operation would be self-defeating, and would in fact not produce any work.
	en.wikipedia.org /wiki/Brownian_ratchet (326 words)

	Scientific American: Science and the Citizen: Taming Maxwell's Demon: February 1999
		One incarnation of the demon, devised by the late Richard Feynman, is a ratcheted gear attached to a microscopic propeller.
		Brownian motion could even be the basis for a computer, as Charles H. Bennett of IBM argued in the early 1980s.
		Brownian motors are one more example of how scientists and engineers have come to see noise as a friend rather than merely a foe.
	www.gg.caltech.edu /~avalos/stuff/download/SciAm/brownian_motor.html (914 words)

	APS physics tip sheet #62
		Brownian motion is the random jitter of small particles that are bumped about by molecules.
		Brownian motion can be harnessed to create microscopic motors that are driven by molecular battering (for a recent example of an experimentally realized Brownian motor see Phys.
		Therefore, the researchers propose, using some external force to drive a Brownian motor in reverse could cause heat to flow from a colder region to a warmer one, much as household heat pumps cool homes with a motor that moves heat outside.
	www.eurekalert.org /pub_releases/2006-05/aps-apt052306.php (985 words)

	Coupled Brownian Motors
		Then, it is possible to construct Brownian motors which are driven by microscopic nonequilibrium fluctuations.
		Such motors may be found in biological systems operating far from equilibrium.
		When many Brownian particles driven by multiplicative noise are coupled, many interesting phenomenon are induced through non-equilibrium phase transition and breaking of ergodicity.
	www.kawai.phy.uab.edu /research/motor (417 words)

	Controllable 3D Brownian motor (Site not responding. Last check: 2007-09-29)
		We demonstrate a Brownian motor, based on cold atoms in optical lattices, where isotropic random fluctuations are rectified in order to induce controlled atomic motion in arbitrary directions.
		In contrast to earlier demonstrations of ratchet effects, our Brownian motor operates in potentials that are spatially and temporally symmetric, but where spatiotemporal symmetry is broken by a phase shift between the potentials and asymmetric transfer rates between them.
		The Brownian motor is demonstrated in three dimensions and the noise-induced drift is controllable in our system.
	www.tp.umu.se /~dion/publi/sjolund06_bm.html (134 words)

	Brownian Ratchet Model of Uplift (Site not responding. Last check: 2007-09-29)
		I stumbled on a the notion of a Brownian Ratchet motor in a Scientific American magazine in a Doctor's office this morning, which has some interesting applications to a networked theory of uplift.
		Basically, Brownian Ratchets are a way of filtering things which are moving around according to Brownian motion - molecules bouncing around due to random collisions.
		Since Brownian motion displaces small particles more than large ones, the ratchet can be used for filtering viruses by their size, or polluting particles from water.
	www.omidyar.net /group/netchange/news/15 (957 words)

	Brownian Molecular Motors
		Biomolecular motors (kinesin-protein process and bacterial flagellar motor) transport substance at the nanoscale level within biological cells, and the motor-cargo connected tether is elastic allowing the motor to defuse rapidly.
		Other problems which must be addressed is the relationship between functionality, operation, actuation and sensing, feedback mechanism, etc. Research in these areas supports the development of a fundamental understanding of nanobiostructures and processes, nanobiotechnology, and techniques for a broad range of applications in biomaterials, biosystem-based electronics, agriculture, energy, medicine, and health.
		The parameters of the mathematical model are identified, and the feasibility of the derived equations which model the Brownian motor dynamic and steady-state responses is documented.
	www.foresight.org /Conferences/MNT9/Abstracts/LyshevskiM (492 words)

	Molecular Motors: A Bibliography
		Astumian, ``Thermodynamics and kinetics of a brownian motor,'' Science 276 (1997) 917.
		Kramers, ``Brownian motion in a field of force and the diffusion model of chemical reactions,'' Physica 7 (1940) 284.
		Simon A; Libchaber A. Escape and synchronization of a brownian particle.
	www.pct.espci.fr /~luca/motors.html (800 words)

	Postdoctoral and Research Fellows
		The second law of thermodynamics says that, as long as the system is left alone and remains in thermal equilibrium, particles in a ratchet can not diffuse in any preferential direction, in spite of the spatial asymmetry.
		Molecular motors are biological machines of only about 0.01 µm size which, for instance, perform transport tasks, generate force, and play a role in in cell mitosis.
		A physical model for how such a Brownian motor may work is the 'ratchet'.
	www.phys.unsw.edu.au /STAFF/RESEARCH/linke.html (965 words)

	Brownian Motor
		Due to the fluctuating force caused by the pushing molecules of the surrounding fluid or gas the Brownian particle may overcome the potential barrier moving to the left or to the right.
		Thus a Brownian motor does not violate any law of thermodynamics it only turns one type of work into another one.
		Nevertheless the fluctuating force due to the heat bath is essential for a Brownian motor.
	monet.physik.unibas.ch /~elmer/bm (724 words)

	[No title] (Site not responding. Last check: 2007-09-29)
		We propose a simplified model, consisting of units involving only hard core interactions, that can be studied in great detail by molecular dynamics and for which an exact analytic treatment is possible in the limit of dilute gases.
		In particular we calculate the speed and heat conductivity of the Brownian motor that appears when two reservoirs at different temperature are considered.
		Van den Broeck, R. Kawai and P. Meurs,``Microscopic Analysis of a Thermal Brownian Motor", Phys.
	uqbar.rockefeller.edu /talks/vandenbroeck.html (158 words)

	Ken Brubaker : Kenglish: Brownian Architect (Site not responding. Last check: 2007-09-29)
		Applications managed by Browning Architects are characterized by Brownian Architecture.
		The primary way to produce a coherent architecture when dealing with a Brownian Architect is to employ a Brownian Motor.
		The concept is to ignore architectural decisions and continue to discuss the design problem until the Brownian Architect randomly lands on the correct decision.
	dotnetjunkies.com /WebLog/kenbrubaker/archive/2005/09/12/brownianarchitect.aspx (113 words)

	A Chemically Reversible Brownian Motor: Application to Kinesin and Ncd - Astumian, Derenyi (ResearchIndex) (Site not responding. Last check: 2007-09-29)
		Abstract: Kinesin and nonclaret disjunctional protein (ncd) are two microtubule-based molecular motors that use energy from ATP hydrolysis to drive motion in opposite directions.
		Is it some subtle feature of the structure of the motor domains, not apparent in x-ray diffraction studies, or possibly some difference near the neck regions far from the microtubule binding...
		A Brownian Dynamics Model of Kinesin in Three Dimensions..
	citeseer.ist.psu.edu /257030.html (282 words)

	The influence of chromosome flexibility on chromosome transport during anaphase A -- Raj and Peskin 103 (14): 5349 -- ...
		motor that is connected to its cargo by an elastic spring, with
		in the model by random forces, as in Brownian dynamics.
		of the motor parameters, which is adjusted to give the correct
	www.pnas.org /cgi/content/short/103/14/5349?rss=1 (328 words)

	A Chemically Reversible Brownian Motor: Application to Kinesin and Ncd -- Astumian and Derényi 77 (2): 993 -- ...
		A Chemically Reversible Brownian Motor: Application to Kinesin and Ncd -- Astumian and Derényi 77 (2): 993 -- Biophysical Journal
		Kinesin and nonclaret disjunctional protein (ncd) are two microtubule-based molecular motors that use energy from ATP hydrolysis
		because the motors function as dimers, the explanation involves
	www.biophysj.org /cgi/content/abstract/77/2/993 (316 words)

	The world's smallest refrigerator
		According to Nature, two theoretical physicists have used the Brownian motion to design a molecular-scale refrigerator powered by 'nano' paddles.
		Their mini fridge is composed of two pools of molecules separated by an insulating membrane.
		Their idea is based on the Brownian motion which is "the random jitter of small particles that are bumped about by molecules," according to an American Physical Society news release.
	www.primidi.com /2006/05/31.html (494 words)

	Molecules off equilibrium
		E 57, 7297 (1998): Parrondo - Reversible ratchets as Brownian...
		Transient behavior of particle transport in a Brownian motor
		Random walks of molecular motors arising from diffusional encounters with immobilized filaments
	www.fzu.cz /~slanina/bookmark_files/bkm1.html (1727 words)

	SPIE Bookstore
		About a decade ago Brownian motors were introduced as a possible mechanism for motor protein mobility.
		While some experiments support Brownian motor mechanisms, others are more consistent with traditional power stroke models.
		Depending on parameter values, this motor works as a power stroker, a Brownian motor or a hybrid of the two.
	bookstore.spie.org /index.cfm?fuseaction=DetailPaper&ProductId=609464&coden= (189 words)

	Einstein's Explanation of Brownian Motion Applet (Site not responding. Last check: 2007-09-29)
		This Java applet is a simple demonstration of Einstein's explanation for Brownian Motion.
		Brownian by Edward Palmer showing distance traveled as a function of time.
		Brownian Motor, how to build a perpetual motion machine from Brownian Motion.
	galileo.phys.virginia.edu /classes/109N/more_stuff/Applets/brownian/applet.html (254 words)

	JARS.COM - The #1 Java Review Service - Brownian Motor
		A Brownian motor turns a random walk (i.e., Brownian motion) into a directed motion without violating the second law of thermodynamics.
		You can do hands-on experiments by changing the parameters interactively during the motor is running.
		This allows you to get a feeling under which condition a Brownian motor works as a motor.
	www.jars.com /science/physics/resource.php/11399 (241 words)

	From Maxwell demon to Brownian motor
		Several versions of a hard disc microscopic ratchet are introduced and studied with molecular dynamics.
		While, at equilibrium, no rectification of the fluctuations takes place, a systematic motion appears when a temperature difference is applied to different units of the motor.
		In the limit of dilute gases, an exact analytic calculation of its properties is found to be in excellent agreement with molecular dynamics simulations.
	stacks.iop.org /1367-2630/7/10 (196 words)

	8.592/lec20 (Site not responding. Last check: 2007-09-29)
		General scheme of motor transport with the consumption of ATP (page 1 of lecture notes)
		Animation of energy landscape for a rotary motor
		"The force exerted by a molecular motor," M.E. Fisher and A.B. Kolomeisky, PNAS 96, 6597 (1999).
	web.mit.edu /8.592/www/lectures/lec20 (86 words)

	Halfbakery: Microflappers
		I thought maybe you could use a piezo motor (that has lots of little piezo elements that take turns rotating the shaft) in reverse.
		I can find plenty of theories, and they seem to require that the ratchet is turned on and off.
		The wikipedia link for Brownian motors describes what they are, but there are no references to any real Brownian motors.
	www.halfbakery.com /lr/idea/Microflappers (863 words)

	Tian Y. Tsong (Site not responding. Last check: 2007-09-29)
		Catalytic wheel, Brownian motor, and biological energy transduction.
		Electric field-enforced conformational oscillation induces pumping of a ligand from the left compartment to right when the activation barrier of the ligand and proteins are as shown.
		• Tsong, T.Y. Na,K-ATPase as A Brownian Motor: Electric Field-induced Conformational Fluctuation Leads to Uphill Pumping of Cation in the Absence of ATP.
	www.cbs.umn.edu /BMBB/faculty/emeritus/Tsong.T.Y.html (1513 words)

	kinderlehrer abstract
		Diffusion mediated transport is implicated in the operation of many molecular level systems.
		These include some liquid crystal and lipid bilayer systems, and, especially, the motor proteins responsible for eukaryotic cellular traffic.
		All of these systems are extremely complex and involve subtle interactions on varying scales.
	www.math.umn.edu /arb/friedman/friedman_kinderlehrer_abst.html (127 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		We have realized a Brownian motor by using cold atoms in a dissipative optical lattice as a model system.
		In our experiment the optical potential is spatially symmetric and the time symmetry of the system is broken by applying appropriate zero-mean ac forces.
		We identify a regime of rectification of forces and a regime of rectification of fluctuations, the latter corresponding to the realization of a Brownian motor.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=20571572 (214 words)

	» The world's smallest refrigerator \| Emerging Technology Trends \| ZDNet.com (Site not responding. Last check: 2007-09-29)
		The left part describes the chiral — or asymmetrical — rotor placed across an insulating wall.
		And Nature confirms that this kind of fridge is not ready yet — even for use in the labs.
		See how breakthroughs such as HP Virtual Connect architecture and HP Insight Control software are changing the face of IT.
	blogs.zdnet.com /emergingtech/index.php?p=253 (703 words)

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