Temporal recompression through a scattering medium via a broadband transmission matrix

The transmission matrix is a unique tool to control light through a scattering medium. A monochromatic transmission matrix does not allow temporal control of broadband light. Conversely, measuring multiple transmission matrices with spectral resolution allows fine temporal control when a pulse is temporally broadened upon multiple scattering, but requires very long measurement time. Here, we show that a single linear operator, measured for a broadband pulse with a co-propagating reference, naturally allows for spatial focusing, and interestingly generates a two-fold temporal recompression at the focus, compared with the natural temporal broadening. This is particularly relevant for non-linear imaging techniques in biological tissues.Comment: 4 pages, 3 figure

Enhanced nonlinear imaging through scattering media using transmission matrix based wavefront shaping

Despite the tremendous progresses in wavefront control through or inside complex scattering media, several limitations prevent reaching practical feasibility for nonlinear imaging in biological tissues. While the optimization of nonlinear signals might suffer from low signal to noise conditions and from possible artifacts at large penetration depths, it has nevertheless been largely used in the multiple scattering regime since it provides a guide star mechanism as well as an intrinsic compensation for spatiotemporal distortions. Here, we demonstrate the benefit of Transmission Matrix (TM) based approaches under broadband illumination conditions, to perform nonlinear imaging. Using ultrashort pulse illumination with spectral bandwidth comparable but still lower than the spectral width of the scattering medium, we show strong nonlinear enhancements of several orders of magnitude, through thicknesses of a few transport mean free paths, which corresponds to millimeters in biological tissues. Linear TM refocusing is moreover compatible with fast scanning nonlinear imaging and potentially with acoustic based methods, which paves the way for nonlinear microscopy deep inside scattering media

Determination of Ceres mass based on the most gravitationally efficient close encounters

Here is presented recalculated value of the mass of Ceres, based on explicit tracking of its gravitational influence on orbits evolution of 21 selected asteroids during their mutual close encounters (CE). It was applied a new modified method (MM) for mass determination, based on the connecting of pre-encounter observations to the orbit determined from post-encounter ones. The calculated weighted mean value of Ceres mass, based on modified method, is $(4.54\pm0.07)\,10^{-10}M_{\odot}$ while standard procedure (SM) provided result of $(4.70\pm0.04)\,10^{-10}M_{\odot}$. We found that correlation between individual estimated masses based on modified and standard method is 0.78, which confirms reliability of using modified method.Comment: MNRAS:Accepted 2011 September 28. Received 2011 September 28; in original form 2011 January 2

Report of the Board of Governors and Address of the President

I would like to discuss with you for a few minutes some of the more important functions of the Board of Governors. Their work is largely done by committees, and I shall call your attention to the work of a number of committees. The fact that all of the committees are not mentioned does not mean that their work is not important. It may mean that it has made a more complete report and will be reported from the floor, and I shall cover only a few of them

A noise study of the A-6 airplane and techniques for reducing its aural detection distance

A study was undertaken to determine the noise reduction potential of the A-6 airplane in order to reduce its aural detection distance. Static and flyby noise measurements were taken to document the basic airplane signature. The low-frequency noise which is generally most critical for aural detection was found to be broad-band in nature from this airplane, and its source is the turbojet engine exhaust. High-frequency compressor noise, which is characteristic of turbojet powerplants, and which is prominent at close range for this airplane, has no measurable effect on aural detection distance. The use of fluted-engine exhaust nozzles to change the far-field noise spectra is suggested as a possible means for reducing the aural detection distances. Detection distances associated with eight-lobe and four-lobe nozzles are estimated for a 1,000-foot altitude and grassy terrain to decrease from 4 miles to about 3 miles, and from 3 miles to about 2 miles for a 300-foot altitude and grassy terrain

Noise reduction studies for the Cessna model 337 (0-2) airplane

A study was undertaken to determine the noise reduction potential of the 0-2 airplane in order to reduce its aural detection distance. Static and flyover noise measurements were made to document the noise signature of the unmodified airplane. The results show that significant reductions in aural detection distance can be achieved by the combination of propeller geometry changes and the addition of engine exhaust mufflers. The best results were estimated for the aircraft equipped with a six-blade propeller operating at 3/4 engine speed in combination with a 3.49 cubic foot exhaust muffler installed on each engine. Detection distance for the modified aircraft is estimated to be reduced from about 4-1/4 miles to about 1-1/2 miles when the aircraft is operating at an altitude of 1,000 ft over grassy terrain. Reducing the altitude to 300 ft over a leafy jungle ground cover should reduce the aural detection distance to 0.9 miles. Reduced aural detection distances were also indicated for a modification utilizing a direct-drive six-blade propeller of reduced radius along with smaller exhaust mufflers

Factors That Impact the Achievement Gap Between African American Male and Female Siblings

This study examined factors that impact the achievement gap between American male and African American female siblings. The researcher gathered data through interviews and academic artifacts consisting of Georgia\u27s writing test for grades 8th and 11th, the 8th grade Criteria Reference Competency Test results, and Georgia High School Graduation test requirements. Through this qualitative research, participants including : African American male and African American female siblings, African American parents, teachers, and administrators were able to explain personal experiences that impacted the academic success of African American males and African American female siblings. The African American male and African American female siblings, teachers, and administrators were all affiliated with a Southeastern Georgia high school during the 2008-2011 academic school years. Each participant was asked specific interview questions to determine their perspective on factors that impact the achievement gap between African American male and African American female siblings. Factors contributing to the achievement gap between African American male and African American female siblings consist of: (1) social environment, (2) family support, (3) parenting, (4) education, and (5) order of siblings. Data from the study also revealed five 2 themes such as: (1) parent expectation, (2) peer acceptance, (3) school culture. (4) family relationship, and (5) teacher/student relationship that impact the academic success of African American males. In short, African American male students\u27 academic success improved when they are understood, nurtured, and supported

King Fred: How the British King Who Never Was Shaped the Modern Monarchy

This thesis examines the British monarchy in the eighteenth century and how the philosophy of Frederick, Prince of Wales, helped to shape that monarchy. The early Hanoverians were seen with contempt by many of their subjects, often being ridiculed as ignorant outsiders. They helped matters none by their indifference to Britain, its people, or its culture. Prince Frederick, George II’s eldest son, however, changed all of this. His philosophy on kingship, influenced by Henry, Viscount Bolingbroke’s work, The Patriot King, helped to change the perception of the Hanoverian dynasty. When Prince Frederick died in 1751 before he could take the throne, it was left up to his son, Prince George, to carry out Frederick’s vision. As George III, he fulfilled the philosophy and became the embodiment of the patriot king. This resulted in a surge in popularity for the Hanoverians, solidifying their place on the British throne

The nuclear scissors mode within two approaches (Wigner function moments versus RPA)

Two complementary methods to describe the collective motion, RPA and Wigner function moments method, are compared on an example of a simple model - harmonic oscillator with quadrupole-quadrupole residual interaction. It is shown that they give identical formulae for eigenfrequencies and transition probabilities of all collective excitations of the model including the scissors mode, which here is the subject of our special attention. The exact relation between the variables of the two methods and the respective dynamical equations is established. The normalization factor of the "synthetic" scissors state and its overlap with physical states are calculated analytically. The orthogonality of the spurious state to all physical states is proved rigorously.Comment: 39 page