The application of the radiation pressure force for the trapping of atoms and neutral particles was pioneered by Arthur Ashkin cite{ashkin70s}. This was followed by a plethora of seminal experiments utilizing the radiation pressure force cite{ashkin80}, for example in the displacement and levitation in air and water of micron-sized particles cite{ashkin-levitate}, and together with Steve Chu, for the development of a stable three-dimensional atom cooling and trapping experiment using frequency-detuned counter-propagating laser beams cite{chu-MOT}. In particular, the demonstration of {it optical tweezers} cite{ashkin-tweezer}, based largely on the transverse gradient force of a single focused Gaussian optical beam was a significant contribution to optical trapping in biology cite{ashkin-tweezera}.
In biological systems, optical tweezers were first used to trap and manipulate viruses and bacteria cite{bacteria}. This was followed by a burgeoning number of experiments using optical tweezers for measurements of DNA/RNA stretching and unfolding cite{gore, bustamante, bustamantea, bryant-dna, smith}, intracellular probing, manipulation of gamete cells, trapping of vesicles, membranes and colloids cite{langblock, neuman} and DNA sequencing using RNA polymerase cite{greenleaf}. In particular, for the first time, quantitative biophysical studies of the kinetics of molecular motors cite{bustamante-motor} (e.g. myosin cite{myosin} and kinesin cite{kinesin}) at the single molecule level was made possible with the use of optical tweezers. Coupled with conventional position sensitive detectors (i.e. using quadrant photodetectors cite{langblock, gittes, pralle}), the position of, and force on, a bead tethered to a molecular mot...
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...s of a single-base pair scale (e.g. 3.4~AA~on dsDNA) cite{moffitt} and the bacterial DNA translocase FtsK moves at speeds of 5 kilobases per second cite{pease}. Therefore, enhanced particle sensing could elucidate these finer features with greater sensitivity than conventional particle sensing techniques in optical tweezers systems.
This paper begins by formalizing an optimal parameter estimation procedure for particle sensing based on the analysis of the spatial properties of the field scattered by a particle in an optical tweezers. We show that split detection is non-optimal and consequently propose an optimal measurement scheme based on spatial homodyne detection. The efficacy of particle sensing is evaluated using the signal-to-noise ratio (SNR) and sensitivity measures; and the efficacy of spatial homodyne detection and split detection systems are compared.
5th Feb, 2014. Wolf, Johnathan. " The Spotlights." Wolf, Johnathan. AP Physics B. Barron’s:
The main goal for our experiment was to learn how to examine DNA when there is only a small
The small size ranging from 0.1 to 10 micrometres of nanobots make it difficult to be constructed. The process of working atom by atom and molecule by molecule is monotonous work and the miniaturization of synthetic mechanisms to a nanoscale will only be achievable with the advancement of research in metallurgy.
7 Serway, Raymond A., Robert J. Beichner, and John W. Jewett, Jr. Physics for Scientists and Engineers. 5th ed. Philadelphia: Saunders College Publishing, 2000.
physics. The work of Ernest Rutherford, H. G. J. Moseley, and Niels Bohr on atomic
Low Copy Number (LCN) is another method that is now used. LCN is a type of DNA profiling. It works by copying DNA molecules enough times so that the DNA can be detected by the analyser. When using the LCN technique the DNA sample is often copied about 34 times. This technique is capable of turning just one molecule of DNA into a number of molecules. There are other DNA profiling kits like SGM+ and the Identifier which work much the same as the LCN (www.theforensicinstitute.com).
Nanotechnology is the manipulation of structures at nano levels. It uses incredibly small materials, devices, and systems to manipulate matter. These structures are measured in nanometers, or one billionth of a meter, and can be used by themselves or as part of larg...
One can almost feel the searing penetration of Lewis Thomas’ analytical eye as it descends the narrow barrel of the microscope and explodes onto a scene of vigorous, animated, interactive little cells—cells inescapably engrossed in relaying messages to one another with every bump and bounce; with every brush of the elbow, lick of the stamp, and click of the mouse…
Ballantyne, Jack, George Sensabaugh, and Jan Witkowski. DNA Technology and Forensic Science. New York: Cold Spring Harbor Laboratory Press, 1989.
Most microscopes, including those in schools and laboratories today, are optical microscopes. They use glass lenses to enlarge, or magnify, an image. An optical microscope cannot produce an image of an object smaller than the length of the light wave in use. To see anything smaller than 2,000 angstroms (about 1/250,000 of an inch) a wave of shorter length would have to be used. In 1923, a French physicist Louis de Broglie suggested that electrons, like light, travel in a wave. In addition, the wavelength of electrons is much shorter than the wavelength of light.
In this experiment a Thomson tube can be used to measure the deflection of electrons in magnetic and electric fields. A Thomson tube is a cathode ray tube which contains an electron gun and a florescent screen. The florescent screen illuminated when the electron gun was turned on and from this the trajectory of the electrons can be measured. By applying a known voltage for both the electric and magnetic fields the charge of the electron c...
Serway, Raymond A, and Robert J Beichner. Physics: For Scientists and Engineers. United States of
American Institute of Physics. Vol. 1051 Issue 1 (2008). Academic Search Premier.> 224. http://login.ezproxy1.lib.asu.edu/login?url=http://search.ebscohost.com.ezproxy1.lib.asu.edu/login.aspx?direct=true&db=aph&AN=34874307&site=ehost-live.
Schultz, James. "Force Fields and 'Plasma' Shields Get Closer to Reality." Technology 25 July 2000: 20 pars. Web. 25 Oct. 2010. .
Technology in the last few decades has impacted our understanding of biological entities greatly, the genome project being a prime example. The progress that biology sees follows closely with the development of new technology. It is very important to understand and visualise the composition and structures of biological materials or samples in order to extend and correlate this to the principles of life. Microscopy is a by far the most used and the most relevant technique in this regard. However the short comings in the technological aspect of this greatly limit the usage of this to comprehend the specifics.