Efficient two-sample functional estimation and the super-oracle phenomenon

We consider the estimation of two-sample integral functionals, of the type that occur naturally, for example, when the object of interest is a divergence between unknown probability densities. Our first main result is that, in wide generality, a weighted nearest neighbour estimator is efficient, in the sense of achieving the local asymptotic minimax lower bound. Moreover, we also prove a corresponding central limit theorem, which facilitates the construction of asymptotically valid confidence intervals for the functional, having asymptotically minimal width. One interesting consequence of our results is the discovery that, for certain functionals, the worst-case performance of our estimator may improve on that of the natural `oracle' estimator, which is given access to the values of the unknown densities at the observations.Comment: 82 page

Cryogenic shutter

A magnetically operated shutter mechanism is provided that will function in cryogenic or cryogenic zero gravity environments to selectively block radiation such as light from passing through a window to a target object such as a mirror or detector located inside a cryogenic container such as a dewar. The mechanism includes a shutter paddle blade that is moved by an electromagnetically actuated torquing device between an open position where the target object is exposed to ambient radiation or light and a closed position where the shutter paddle blade shields the ambient radiation or light from the target object. The purpose of the shuttering device is to prevent the mirror or other target object from being directly exposed to radiation passing through the window located on the side wall of the dewar, thereby decreasing or eliminating any temperature gradient that would occur within the target object due to exposure to the radiation. A special nylon bearing system is utilized to prevent the device from binding during operation and the paddle blade is also thermally connected to a reservoir containing cryogen to further reduce the internal temperature

Inward electrostatic precipitation of interplanetary particles

An inward precipitator collects particles initially dispersed in a gas throughout either a cylindrical or spherical chamber onto a small central planchet. The instrument is effective for particle diameters greater than about 1 µm. One use is the collection of interplanetary dust particles which are stopped in a noble gas (xenon) by drag and ablation after perforating the wall of a thin-walled spacecraft-mounted chamber. First, the particles are positively charged for several seconds by the corona production of positive xenon ions from inward facing needles placed on the chamber wall. Then an electric field causes the particles to migrate toward the center of the instrument and onto the planchet. The collection time (of the order of hours for a 1 m radius spherical chamber) is greatly reduced by the use of optimally located screens which reapportion the electric field. Some of the electric field lines terminate on the wires of the screens so a fraction of the total number of particles in the chamber is lost. The operation of the instrument is demonstrated by experiments which show the migration of carbon soot particles with radius of approximately 1 µm in a 5-cm-diam cylindrical chamber with a single field enhancing screen toward a 3.2 mm central collection rod

Comparison of Abstinence and Coital Frequency between Two Natural Methods of Family Planning

Problem Statement: The length of periodic abstinence, due to overestimation of the fertile phase of the menstrual cycle is often a reason for dissatisfaction, discontinuation, and user error with natural family planning (NFP) methods. The objective of this research was to compare the length of required abstinence (i.e., estimated fertility) and coital frequency between two NFP methods. Study Design: Analysis of existing data from a 12 month prospective comparison study in which participants were randomized into either an electronic hormonal fertility monitor (EHFM) group or a cervical mucus monitoring (CMM) group, both of which included a fertility algorithm as a double check for the beginning and end of the estimated FW. The current study involved 197 women (mean age 29.7, SD=5.4) who used the EHFM to estimate the FW and 162 women (mean age 30.4, SD=5.3) who used CMM to estimate the FW. They produced 1,669 menstrual cycles of data. Number of days of estimated fertility and coitus was extracted from each cycle and t-tests were used to compare the means of these two variables between the two NFP methods. Results: After six months of use, the EHFM group had statistically fewer days of estimated fertility than the CMM group (13.25 days, SD=2.79 versus 13.65 days, SD=2.99; t=2.07, p = .04) and significantly more coitus (4.22 coital acts, SD=3.16 versus 4.05 acts, SD=2.88, t=1.17, p=.026). Conclusion: The use of the EHFM seems to provide more objectivity and confidence in self-estimating the FW and use of non-fertile days for intercourse when avoiding pregnancy

An Economic Model of Fair Use

The doctrine of fair use allows limited copying of creative works based on the rationale that copyright holders would consent to such uses if bargaining were possible. This paper develops a formal model of fair use in an effort to derive the efficient legal standard for applying the doctrine. The model interprets copies and originals as differentiated products and defines fair use as a threshold separating permissible copying from infringement. The analysis highlights the role of technology in shaping the efficient standard. Discussion of several key cases illustrates the applicability of the model.Fair use, Copyright law, Technological improvement

Coherent communication link using diode-pumped lasers

Work toward developing a diffraction limited, single frequency, modulated transmitter suitable for coherent optical communication or direct detection communication is discussed. Diode pumped, monolithic Nd:YAG nonplanar ring oscillators were used as the carrier beam. An external modulation technique which can handle high optical powers, has moderate modulation voltage, and which can reach modulation rates of 1 GHz was invented. Semiconductor laser pumped solid-state lasers which have high output power (0.5 Watt) and which oscillate at a single frequency, in a diffraction limited beam, at the wavelength of 1.06 microns were built. A technique for phase modulating the laser output by 180 degrees with a 40-volt peak to peak driving voltage is demonstrated. This technique can be adapted for amplitude modulation of 100 percent with the same voltage. This technique makes use of a resonant bulk modulator, so it does not have the power handling limitations of guided wave modulators

SUPPLY CHAINS MAY DELIVER SAFER TOMATOES AND STRAWBERRIES

Food Consumption/Nutrition/Food Safety,