Adaptive Optimisation of Illumination Beam Profiles in Fluorescence Microscopy

Wide-field fluorescence microscope techniques such as single/selective plane illumination microscope (SPIM) are typically configured to image large regions of a sample at once. Here the illumination beam provides uniform excitation of several biological features across the region, `sliced' to a thickness of between 5-10 microns. In this paper we propose a simple alteration to the optical configuration of a SPIM by switching the light-sheet- forming cylindrical lens with a spatial light modulator. This has the potential to adaptively reconfigure the light sheet geometry to improve the optical sectioning of specific biological features, rather than the thicker sectioning of several features at once across a larger observation field-of-view. We present a prototype version of such a system, referred to as an Adaptive-SPIM (A-SPIM) system. We then suggest that the direct recording of illumination beam shapes within the working microscope system can better facilitate the analysis and subsequent re-configuration of the illumination beam to a specific geometry, and summarise the design and operation of a device that we have developed specifically for this purpose. We finally present reconstructed quantitative three dimensional flux maps of illumination beams from three microscope configurations taken using this miniature high-dynamic range beam profiling device, comparing the beam geometry of a regular SPIM system with our prototype A-SPIM system, and suggesting future improvements

A Shack-Hartmann wavefront sensor projected on to the sky with reduced focal anisoplanatism

A method for producing a laser guide star wavefront sensor for adaptive optics with reduced focal anisoplanatism is presented. A theoretical analysis and numerical simulations have been carried out and the results are presented. The technique, named Sky-Projected Laser Array Shack–Hartmann (SPLASH), is shown to suffer considerably less from focal anisoplanatism than a conventional laser guide star system. The method is potentially suitable for large telescope apertures (8 m), and possibly for extremely large telescopes

Diamond like carbon coatings for potential application in biological implants – a review

Production of wear debris has been linked to the failure of numerous hip implants. With the current focus on increasing the implant longevity, thus wear and corrosion resistance is important. Hard coatings have the potential to reduce the wear and corrosion. Diamond like Carbon (DLC) coatings exhibit properties that could make them viable for implants. This paper critically reviews previously published research into usage of DLC coatings for implants. Overall DLCs seem to be an effective coating for implants but with the variance in results, further testing is required for clarification of us

Experimental investigation of solar heating of bridge decks

The addition of monomers or the inclusion of wax within highway bridge decks are two methods being used to prevent salt penetration during winter deicing. Both of these methods require the addition of heat until the upper two inches of bridge deck reaches from 160-190 F. This study investigated the potential for using solar energy as a means of providing the required heat. The bridge was modeled analytically and the time varying temperature distribution was determined for both a flat plate type cover collector and focusing collector scheme did show promise for providing the required heat. Both models suffered from lack of accurate thermal properties data for the concrete. Experimental studies were conducted on a simulated bridge deck using flat plate covers and Northrup focusing Fresnel Lens collectors. Neither scheme was able to provide the desired temperatures. A major difficulty encountered was the design of an appropriate heat exchanger to transfer the collected energy from the heat transfer flud to the bridge deck. Several different designs were tested, but none of the methods used would provide the desired bridge deck temperatures for the collector area used. The collectors did not perform up to their expectations.4-77 to 6-79N

Adaptive optimisation of illumination beam profiles in fluorescence microscopy

Wide-field fluorescence microscope techniques such as single/selective plane illumination microscope (SPIM) are typically configured to image large regions of a sample at once. Here the illumination beam provides uniform excitation of several biological features across the region, `sliced' to a thickness of between 5-10 microns. In this paper we propose a simple alteration to the optical configuration of a SPIM by switching the light-sheet- forming cylindrical lens with a spatial light modulator. This has the potential to adaptively reconfigure the light sheet geometry to improve the optical sectioning of specific biological features, rather than the thicker sectioning of several features at once across a larger observation field-of-view. We present a prototype version of such a system, referred to as an Adaptive-SPIM (A-SPIM) system. We then suggest that the direct recording of illumination beam shapes within the working microscope system can better facilitate the analysis and subsequent re-configuration of the illumination beam to a specific geometry, and summarise the design and operation of a device that we have developed specifically for this purpose. We finally present reconstructed quantitative three dimensional flux maps of illumination beams from three microscope configurations taken using this miniature high-dynamic range beam profiling device, comparing the beam geometry of a regular SPIM system with our prototype A-SPIM system, and suggesting future improvements

Constraints, Histones, and the 30 Nanometer Spiral

We investigate the mechanical stability of a segment of DNA wrapped around a histone in the nucleosome configuration. The assumption underlying this investigation is that the proper model for this packaging arrangement is that of an elastic rod that is free to twist and that writhes subject to mechanical constraints. We find that the number of constraints required to stabilize the nuclesome configuration is determined by the length of the segment, the number of times the DNA wraps around the histone spool, and the specific constraints utilized. While it can be shown that four constraints suffice, in principle, to insure stability of the nucleosome, a proper choice must be made to guarantee the effectiveness of this minimal number. The optimal choice of constraints appears to bear a relation to the existence of a spiral ridge on the surface of the histone octamer. The particular configuration that we investigate is related to the 30 nanometer spiral, a higher-order organization of DNA in chromatin.Comment: ReVTeX, 15 pages, 18 figure

Form finding of twisted interlaced structures: a hybrid approach

Our study presents a set of form-finding procedures to explore curved structures made from interlaced panels. Interlacing introduces a particular coupling between assembly components which has to be formulated along with a pertinent flexible body model. We examine here a hybrid approach: panels are simulated a first time using an elastic rod model formulated within a constrained elastic energy minimization where user can virtually buckle, twist and interlace strip assemblies. A thin shell model dynamically integrated comes complementary to the rod approach in order to resolve intersections in case of panels colliding while interlaced. Some conceptual structures are presented to demonstrated the procedure

Diamond like carbon coatings for potential application in biological implants—a review

Production of wear debris has been linked to the failure of numerous hip implants. With the current focus on increasing the implant longevity, thus wear and corrosion resistance is important. Hard coatings have the potential to reduce the wear and corrosion. Diamond like Carbon (DLC) coatings exhibit properties that could make them viable for implants. This paper critically reviews previously published research into usage of DLC coatings for implants. Overall DLCs seem to be an effective coating for implants but with the variance in results, further testing is required for clarification of us

Demonstration of the temporal matter-wave Talbot effect for trapped matter waves

We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure

Kaon Production and Kaon to Pion Ratio in Au+Au Collisions at \snn=130 GeV

Mid-rapidity transverse mass spectra and multiplicity densities of charged and neutral kaons are reported for Au+Au collisions at \snn=130 GeV at RHIC. The spectra are exponential in transverse mass, with an inverse slope of about 280 MeV in central collisions. The multiplicity densities for these particles scale with the negative hadron pseudo-rapidity density. The charged kaon to pion ratios are $K^+/\pi^- = 0.161 \pm 0.002 {\rm (stat)} \pm 0.024 {\rm (syst)}$ and $K^-/\pi^- = 0.146 \pm 0.002 {\rm (stat)} \pm 0.022 {\rm (syst)}$ for the most central collisions. The $K^+/\pi^-$ ratio is lower than the same ratio observed at the SPS while the $K^-/\pi^-$ is higher than the SPS result. Both ratios are enhanced by about 50% relative to p+p and $\bar{\rm p}$+p collision data at similar energies.Comment: 6 pages, 3 figures, 1 tabl