PN lock indicator for dithered PN code tracking loop

In a delay-lock one-delta (+or - 1/2 chip) dithered PN code tracking loop, an indication of lock in the PN code tracking loop is provided by delaying the dithered local PN code by a half chip to produce a +0, -1 dithered PN code that is then multiplied with the received PN-spread IF signal to produce a signal proportional to the correlation of this dithered code offset from the received code. The correlation signal is bandpass filtered, amplified with AGC control, and square-law detected to obtain a dc signal proportional to the degree of correlation. The dc signal is multiplied by the dithering control signal to effectivity substract noise voltage from the lock correlation signal which is then compared with a PN lock status signal

Discriminator aided phase lock acquisition for suppressed carrier signals

A discriminator aided technique for acquisition of phase lock to a suppressed carrier signal utilizes a Costas loop which is initially operated open loop and control voltage for its VCXO is derived from a phase detector that compares the VCXO to a reference frequency thus establishing coarse frequency resolution with the received signal. Then the Costas loop is closed with the low-pass filter of the channel having a bandwidth much greater (by a factor of about 10) than in the I channel so that a frequency discriminator effect results to aid carrier resolution. Finally, after carrier acquisition, the Q-channel filter of the Costas loop is switched to a bandwidth substantially equal to that of the I-channel for carrier tracking

A reference book on rocks and minerals of New England for gifted students in the intermediate grades.

Thesis (Ed.M.)--Boston Universit

Quantum fluctuations of the electroweak sphaleron: Erratum and Addendum

We correct an error in our treatment of the tadpole contribution to the fluctuation determinant of the sphaleron, and also a minor mistake in a previous estimate. Thereby the overall agreement between the two existing exact computations and their consistency with the estimate is improved considerably.Comment: 4 pages, Dortmund preprint DO-TH-93/19E

The association between graded physical activity in postmenopausal British women, and the prevalence and incidence of hip and wrist fractures.

BACKGROUND: physical activity is promoted for older women as a means of maintaining health and avoiding falls and fractures. Findings relating physical activity of older women to risk of falls and fracture are contradictory. The association between level of physical activity and prevalent and incident hip and wrist fractures was examined in a large representative sample of postmenopausal British women. METHODS: data from the British Women's Heart and Health Study, a cohort study of 4286 postmenopausal women aged 60-79, from 23 UK towns were used. Information on physical activity, anthropometry, falls and hip and wrist fractures from baseline examination and questionnaire (1999-2001) and follow-up questionnaire (2007) were available. Cross-sectional baseline prevalence data were analysed using logistic regression and cohort incidence data using a Cox proportional hazards model examining the association of physical activity with fracture outcomes. RESULTS: 3003 (70%) women, with complete baseline data, were studied. 13.6% had previously fractured a wrist and 1.3% a hip. Analyses unadjusted for confounders showed moderate protective associations between activity and fracture risk. After adjustment for confounders there was a weak trend towards fewer hip fractures (adjusted OR 0.13 [0.01, 1.18]) and more wrist fractures (adjusted OR 1.35 [0.76, 2.48]), amongst most active compared with inactive women. The crude incidence rate of wrist and/or hip fracture was 7.0 [5.9, 8.2] per 1000 person-years. No evidence was found for an association between physical activity and combined incident hip and/or wrist fracture (adjusted rate ratio inactive versus most active 1.69 [0.67, 4.24]). CONCLUSION: no clear associations between graded physical activity and hip/wrist fractures were seen but estimates were imprecise. Physical activities are heterogeneous and individual fracture types and mechanisms differ. Very large prospective observational studies are required to disentangle the precise effects of different activity patterns on different fracture types

Preliminary catalog of pictures taken on the lunar surface during the Apollo 16 mission

A catalog of all pictures taken from the lunar module or the lunar surface during the Apollo 16 lunar stay is presented. The tabulations are arranged for the following specific uses: (1) given the number of a particular frame, find its location in the sequence of lunar surface activity, the station from which it was taken and the subject matter of the picture; (2) given a particular location or activity within the sequence of lunar surface activity, find the pictures taken at that time and their subject matter; and (3) given a sample number from the voice transcript listed, find the designation assigned to the same sample by the lunar receiving laboratory

The Rachel Carson Letters and the Making of Silent Spring

Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance

The Higher Derivative Expansion of the Effective Action by the String-Inspired Method, Part I

The higher derivative expansion of the one-loop effective action for an external scalar potential is calculated to order O(T**7), using the string-inspired Bern-Kosower method in the first quantized path integral formulation. Comparisons are made with standard heat kernel calculations and with the corresponding Feynman diagrammatic calculation in order to show the efficiency of the present method.Comment: 13 pages, Plain TEX, 1 figure may be obtained from the authors, HD-THEP-93-4

Library Research Skills and the Nursing Curriculum: Engaging Students in the Post-Brandon-Hill Era

ABSTRACT. Health science librarians experience challenges when partnering with people from other professional backgrounds such as nursing and with people of different ages. In partnering with people of other backgrounds,it is helpful to recognize the changing nature of research skills and the fact that many 21st century college students lack a print-based concept of research. Helping students to succeed in understanding and participating in the research process is more important than ever due to changes in the nursing profession, the sheer mass of scholarly information, and the challenges of searching for information on the world wide web