Aircraft approach guidance using relative Loran-C navigation

The experiments carried out at MIT during 1984 focussed on two aspects of Loran-C relative navigation that would impact system performance at the sub-microsecond level of accuracy: tracking loop bandwidth and localized field deformation. Figures are given to illustrate the results from both effects

Loran-C approach guidance project current status

There are four areas of work in the Loran-C flight test project. Current results provide performance data on the effects of Signal Noise Ratio (SNR) on the dynamic performance of the receiver filters for Loran-C data, and data on Loran-C grid deformation at a microscale of 100 meters. The Loran-C receiver provides a line of position (LOP) Master and Slave transmitter at an angle 0 to magnetic north. No transformation to latitude-longitude reference frame is required since this is the major source of Loran-C navigation errors. A local coordinate frame is established centered at touchdown point on the runway with directions along and across the runway. A Loran-C data collection system was set up. The Loran-C data are sent directly to an Apple II computer with a 12 inch monitor. The effect of SNR on Loran-C precision is shown for two receiver filters of different frequency response. A set of ground level static readings of touchdown was taken around Hanscom Field and transferred to an accurate detailed layout drawing; this showed local distortions of the average touchdown values

Adam Smith and Three Theories of Altruism

Smith advanced a particular view of altruism that should prove to be relevant to the modem literature on the subject. It provided the back-bone of his critique of three different theories. These three theories have been reincarnated in three modem approaches : Robert Axelrod's "egoistic", Gary Becker's "egocentric", and George Herbert Mead and Robert Frank's "altercentric" views. Axelrod's approach repeats the failing, which Smith found in Mandeville's. Becker's theory echoes the shorteoming, which Smith identified in Hobbes'. Mead/Prank's view duplicates the fault, which Smith uncovered in the approach of Francis Hutcheson and other figures of the Scottish Enlightenment.Egoistic theory, egocentric theory, altercentric theory

Information, Knowledge and the Close of Friedrich Hayek's System: A Comment

The paper argues that there are two separate orders implied in Hayek's open society: market order and liberal order. The distinction rests on a difference between, what is called here, information and knowledge. While information is about facts such as prices, knowledge expresses the agent's belief about the world. Hayek argues that market order is superior to planned order because information is inherently dispersed. He also argues that liberal order is superior to communal order because the development of knowledge is innately personal. The paper contends that Hayek's arguments cannot be conclusively derived from his theories of information and knowledge.Information; Knowledge; Friedrich Hayek

Homogeneous cosmologies and the Maupertuis-Jacobi principle

A recent work showing that homogeneous and isotropic cosmologies involving scalar fields are equivalent to the geodesics of certain effective manifolds is generalized to the non-minimally coupled and anisotropic cases. As the Maupertuis-Jacobi principle in classical mechanics, such result permits us to infer some dynamical properties of cosmological models from the geometry of the associated effective manifolds, allowing us to go a step further in the study of cosmological dynamics. By means of some explicit examples, we show how the geometrical analysis can simplify considerably the dynamical analysis of cosmological models.Comment: 5 page

Semi-optimal Practicable Algorithmic Cooling

Algorithmic Cooling (AC) of spins applies entropy manipulation algorithms in open spin-systems in order to cool spins far beyond Shannon's entropy bound. AC of nuclear spins was demonstrated experimentally, and may contribute to nuclear magnetic resonance (NMR) spectroscopy. Several cooling algorithms were suggested in recent years, including practicable algorithmic cooling (PAC) and exhaustive AC. Practicable algorithms have simple implementations, yet their level of cooling is far from optimal; Exhaustive algorithms, on the other hand, cool much better, and some even reach (asymptotically) an optimal level of cooling, but they are not practicable. We introduce here semi-optimal practicable AC (SOPAC), wherein few cycles (typically 2-6) are performed at each recursive level. Two classes of SOPAC algorithms are proposed and analyzed. Both attain cooling levels significantly better than PAC, and are much more efficient than the exhaustive algorithms. The new algorithms are shown to bridge the gap between PAC and exhaustive AC. In addition, we calculated the number of spins required by SOPAC in order to purify qubits for quantum computation. As few as 12 and 7 spins are required (in an ideal scenario) to yield a mildly pure spin (60% polarized) from initial polarizations of 1% and 10%, respectively. In the latter case, about five more spins are sufficient to produce a highly pure spin (99.99% polarized), which could be relevant for fault-tolerant quantum computing.Comment: 13 pages, 5 figure

Specific fluorescent labeling of chicken myofibril Z-line proteins catalyzed by guinea pig liver transglutaminase

Guinea pig liver transglutaminase has been found to catalyze the covalent incorporation of dansylcadaverine into chicken skeletal muscle myofibril proteins. Epifluorescence microscopy reveals that the incorporated dansylcadaverine is specifically localized at or near the myofibril Z line. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) indicates that actin constitutes a major fraction of the labeled material; the Z-line proteins alpha-actinin and desmin also show significant labeling, as well as tropomyosin, several additional unidentified proteins, and material with an extremely high molecular weight. The Z-line-specific fluorescence can be removed by brief trypsinization, which releases fluorescent alpha-actinin into the supernate. The majority of the fluorescent protein species are resistant to extraction by either 0.6 M KCl or KI. These results, in conjunction with the microscopic localization, suggest that the dansyl- labeled proteins are constituents of the myofibril Z line. A significant amount of fluorescently labeled transglutaminase is also present in labeled myofibrils, which is resistant to extraction with either 0.6 M KCl or KI. This result indicates a strong, noncovalent interaction between the transglutaminase molecule and the myofibril Z line

Comment on: The Vitamin D⁻Folate Hypothesis as an Evolutionary Model for Skin Pigmentation: An Update and Integration of Current Ideas, Nutrients 2018, 10, 554.

In response to a recent article by Jones et al. (Nutrients 10: 554⁻568, 2018) [1], we agree that three distinctive features evolved in Homo erectus prior to the emergence of modern humans.[...]