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.
The main goal for our experiment was to learn how to examine DNA when there is only a small
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…
physics. The work of Ernest Rutherford, H. G. J. Moseley, and Niels Bohr on atomic
The method to use protons such as medical treatment of cancer was proposed by Robert Whilson, who was fade American physicist, in 1946 (McDonald and Fitzek 2010, 257). He argued that the unique physical properties of protons are relevant to utilize this radiation techology in medicine. The principle of the proton beam therapy consists in the appreciable mass of protons than other particles; as a result, the beam slightly broaden and stays focused on the c...
Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the contact forces between material objects. (HS-PS2-6)
In this project, we use three principles which are focusing sunlight to evacuated tube, converting light energy to heat energy and trapping heat energy.
In 2010, optogenetics was named the Nature Method of the Year ("Method of the Year 2010"). While this technique and the researchers who contributed to its development are largely being recognized now, the theory behind optogenetics has existed for several years. In fact, opsins, proteins that undergo conformational changes when exposed to light, had been of interest to many researchers since the 1970s.
Movement speed of DNA in the electric field depends on many factors such as electric power, buffer composition, concentration agarose gels. The higher concentrations of gel, the stronger resistance, which leads to DNA move slower. Moreover, the size of the DNA molecules also affects the speed of their movement in the gel. For example, in the same conditions of the electric field, concentration of agarose and buffer, moving speed between two different DNA molecules base on their sizes, the smaller molecules move faster than bigger ones. Since
This lab demonstrates one type of molecular movement, passive transports, displays the effects solutions have on a cell, a chemical reaction, and how the cell membrane works.
Purpose: The purpose of this lab experiment is to learn how to make a wet mount slide and observe it under a microscope.
DNA fingerprinting requires a sample of cells. For example, a drop of blood left on a crime scene by the assumed culprit. From these cells, DNA is extracted and cut into smaller pieces using ‘restriction enzymes.’ These restriction enzymes are proteins that, when removed from the bacterial cell they grow on, are used to cut DNA. Once the DNA has been cropped into some thousand smaller pieces of varying length, the pieces are put in a gel, in one pile.
Schultz, James. "Force Fields and 'Plasma' Shields Get Closer to Reality." Technology 25 July 2000: 20 pars. Web. 25 Oct. 2010. .
Serway, Raymond A, and Robert J Beichner. Physics: For Scientists and Engineers. United States of
Based on the pattern that is detected beyond the wall by a specific detector – one can distinguish whether the material coming through behaves as either a wave or particle.
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.