Performance of Single- and Multiple-Dish Laser Communications Systems

A comparison is given of three potentially useful types of laser communications systems. These are the incoherent direct detection systems (DDS), the transmitted reference system (TRS) and the coherent local heterodyning system (LHS). Both signle- and multiple-dish receiver systems are considered. In all cases a photomultiplier receiver detector is assumed. In the analysis the wave interference noise (or equivalently, classical noise) has been taken into account. The results are given for the case where the background noise arises from a point source, from rnanv point sources or from a uniformly radiating background. Also, the case where the receiving aperture is not diffraction limited/ is considered. Convenient curves are given which permit one to determine the performance of the three systems for various background conditions and system parameters. It is pointed out that the transmitter power required for a communications system using a multiple-dish receiver complex does not decrease always in direct proportion to the reciprocal of the increase in the number of receiver dishes used. Curves are given showing the receiver collecting aperture loss as a function of the number of collecting apertures

Bankruptcy Courts and Stare Decisis: The Need for Restructuring

Part I of this Note provides background by summarizing the rules of stare decisis. Part II refutes the contention that the present court structure allows bankruptcy judges not to follow domestic district court precedent. Part II asserts that, in pursuit of legitimate ends, bankruptcy judges have employed illegitimate means. Finally, Part II contends that bankruptcy judges are better equipped to make bankruptcy decisions than district judges. Part III concludes that the bankruptcy system should be restructured to allow bankruptcy judges to make decisions without being constrained by district court precedent or appeals. Such reform could achieve the substantive goals desired by bankruptcy judges without undermining the current structure of the judicial system

Communication Channel Model of the Atmosphere for Optical Frequencies

In order to obtain high data rate T.V. picture transmissions from spacecrafts on planetary missions consideration has been given in the past to the use of laser communications systems. If no relay satellite is used a deep space laser communication link would involve propagation through the earths atmosphere to a ground based station. This paper gives consideration to the characteristic of the earths atmosphere as a communication channel. A channel model is given both for clear weather conditions and for inclement weather conditions. For clear weather conditions it is found that the laser atmosphere is a Quasi-Wide-Sense-Stationary correlated Scattering Channel (QWSSCS) which can be fairly accurately characterized by an array of variable gain, variable delay paths. Under inclement weather conditions the channel is characterized by a differential circuit model which is specified by the Input Delay- Spread Function. Data is compiled, for these two channel models, which describes the pertinent parameters/ such as, delay dispersion, tne amplitude distribution, amplitude power spectrum and the two dimentional spacial correlation function. It is found that for good weather conditions, pulses having widths of the order of 2 picosecond can be propagated through the whole atmosphere without appreciable distortion, whereas for inclement weather conditions one is limited to pulse widths of the order of nanoseconds

Detecting high-grade squamous intraepithelial lesions in the cervix with quantitative spectroscopy and per-patient normalization

This study develops a spectroscopic algorithm for detection of cervical high grade squamous intraepithelial lesions (HSILs). We collected reflectance and fluorescence spectra with the quantitative spectroscopy probe to measure nine spectroscopic parameters from 43 patients undergoing standard colposcopy with directed biopsy. We found that there is improved accuracy for distinguishing HSIL from non-HSIL (low grade SIL and normal tissue) when we “normalized” spectroscopy parameters by dividing the values extracted from each clinically determined suspicious site by the corresponding value extracted from a clinically normal squamous site from the same patient. The “normalized” scattering parameter (A) at 700nm, best distinguished HSIL from non-HSIL with sensitivity and specificity of 89% and 79% suggesting that a simple, monochromatic instrument measuring only A may accurately detect HSIL

Samuel Richardson's Revisions to Pamela (1740, 1801)

The edition of Pamela a person reads will affect his or her perception of Pamela's ascent into aristocratic society. Richardson's revisions to the fourteenth edition of Pamela, published posthumously in 1801, change Pamela's character from the 1740 first edition in such a way as to make her social climb more believable to readers outside the novel and to "readers" inside the novel. Pamela alters her language, her actions, and her role in the household by the end of the first edition; in the fourteenth edition, however, she changes in little more than her title. Pamela might begin as a novel that threatens the fabric of class hierarchies, but it ends-both within the plot and externally throughout its many editions-as a novel that stabilizes and strengthens social norms

Personal Properties: Stage Props and Self-Expression in British Drama, 1600-1707

This dissertation examines the role of stage properties-props, slangily-in the construction and expression of characters' identities. Through readings of both canonical and non-canonical drama written between 1600 and 1707-for example, Thomas Middleton's The Revenger's Tragedy (1607), Edward Ravenscroft's adaptation of Titus Andronicus (1678), Aphra Behn's The Rover (1677), and William Wycherley's The Plain Dealer (1677)-I demonstrate how props mediate relationships between people. The control of a character's props often accords a person control of the character to whom the props belong. Props consequently make visual the relationships of power and subjugation that exist among characters. The severed body parts, bodies, miniature portraits, and containers of these plays are the mechanisms by which characters attempt to differentiate themselves from others. The characters deploy objects as proof of their identities-for example, when the women in Behn's Rover circulate miniatures of themselves-yet other characters must also interpret these objects. The props, and therefore the characters' identities, are at all times vulnerable to misinterpretation. Much as the props' meanings are often disputed, so too are characters' private identities often at odds with their public personae. The boundaries of selfhood that the characters wish to protect are made vulnerable by the objects that they use to shore up those boundaries. When read in relation to the characters who move them, props reveal the negotiated process of individuation. In doing so, they emphasize the correlation between extrinsic and intrinsic worth. They are a measure of how well characters perform gender and class rolls, thereby demonstrating the importance of external signifiers in the legitimation of England's subjects, even as they expose "legitimacy" as a social construction

Beyond aspect: will be -ing and shall be -ing

This article discusses the synchronic status and diachronic development of will be -ing and shall be -ing (as in I’ll be leaving at noon).2 Although available since at least Middle English, the constructions did not establish a significant foothold in standard English until the twentieth century. Both types are also more prevalent in British English (BrE) than American English (AmE). We argue that in present-day usage will/shall be -ing are aspectually underspecified: instances that clearly construe a situation as future-in-progress are in the minority. Similarly, although volition-neutrality has been identified as a key feature of will/shall be -ing, it is important to take account of other, generally richer meanings and associations, notably ‘future-as-matter-of-course’ (Leech 2004), ‘already-decided future’ (Huddleston & Pullum et al. 2002) and non-agentivity. Like volition-neutrality, these characteristics appear to be relevant not only in contemporary use, but also in their historical expansion. We show that the construction has evolved from progressive aspect towards more subjectivised evidential meaning

A Real-Time Tool Positioning Sensor for Machine-Tools

In machining, natural oscillations, and elastic, gravitational or temperature deformations, are still a problem to guarantee the quality of fabricated parts. In this paper we present an optical measurement system designed to track and localize in 3D a reference retro-reflector close to the machine-tool's drill. The complete system and its components are described in detail. Several tests, some static (including impacts and rotations) and others dynamic (by executing linear and circular trajectories), were performed on two different machine tools. It has been integrated, for the first time, a laser tracking system into the position control loop of a machine-tool. Results indicate that oscillations and deformations close to the tool can be estimated with micrometric resolution and a bandwidth from 0 to more than 100 Hz. Therefore this sensor opens the possibility for on-line compensation of oscillations and deformations