Progress in Nuclear Magnetic Resonance Spectroscopy Vol. 2. Edited by J. W. Emsley, J. Feeney and L. H. Sutcliffe. Pp. vii + 269. (Oxford, London and New York: Pergamon Press, Ltd, 1967.) 90s. net. Advances in Magnetic Resonance Vol. 2. By John S. Waugh. Pp. xii + 269. (New York: Academic Press, Inc.; London: Academic Press, Inc. (London), Ltd, 1966.) $12.00. Guide to the NMR Empirical Method A Workbook. By Roy H. Bible jun.. Pp. xi + 305. (New York: Plenum Press, 1967.) $9.50.

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Nuclear Magnetic Resonance

Cryogenically cooled probes—a leap in NMR technology

Covering the literature from mid-2004 until the end of 2011, this review continues a previous literature overview on quantitative 1H NMR (qHNMR) methodology and its applications in the analysis of natural products. Among the foremost advantages of qHNMR is its accurate function with external calibration, the lack of any requirement for identical reference materials, a high precision and accuracy when properly validated, and an ability to quantitate multiple analytes simultaneously. As a result of the inclusion of over 170 new references, this updated review summarizes a wealth of detailed experiential evidence and newly developed methodology that supports qHNMR as a valuable and unbiased analytical tool for natural product and other areas of research.

Quantitative 1H NMR. Development and Potential of an Analytical Method: An Update

This paper describes and explains the theory of the feedback principle and then demonstrates how stability of amplification and reduction of modulation products, as well as certain other advantages, follow when stabilized feedback is applied to an amplifier. The underlying principle of design by means of which singing ia avoided is next set forth. The paper concludes with some examples of results obtained on amplifiers which have been built employing this new principle. The carrier-in-cable system dealt with in a companion paper1 involves many amplifiers in tandem with many telephone channels passing through each amplifier and constitutes, therefore, an ideal field for application of this feedback principle. A field trial of this system was made at Morristown, New Jersey, in which seventy of these amplifiers were operated in tandem. The results of this trial were highly satisfactory and demonstrated conclusively the correctness of the theory and the practicability of its commercial application.

Stabilized Feedback Amplifiers

This paper explores the meaning and significance of the term `social practice' and its relation to strategy-as-practice research from the perspective of social theory. Although our remarks are also applicable to other practice-based discussions in management, we discuss strategy practices as a case in point and thus contribute to the strategy-as-practice literature in three ways. First, instead of simply accepting the existence of a unified `practice theory', we outline a genealogical analysis revealing the historical-contingent conditions of its creation. This analysis shows that social practices in general and strategy practices in particular can be approached from either a neo-structuralist and/or neo-interpretative perspective. Second, based on this theoretical argument, we discuss different characteristics of strategy practices and emphasize those aspects not yet fully considered by strategy-as-practice research (e.g. the physical nature of practices). Third, we show that, when studying strategy practices, given an understanding of the alternative theoretical approaches available, the practice of strategy research itself needs to be adjusted so as to accommodate a stronger emphasis on an ethnographic approach that is directed towards uncovering the contextual and hidden characteristics of strategy-making.

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Researching Strategy Practices: A Genealogical Social Theory Perspective

The principle of reciprocity.

http://mriquestions.com/uploads/3/4/5/7/34572113/1-s2.0-s1090780700922298-main.pdf

The quantum origins of the free induction decay signal and spin noise.

The NMR multi-transmit phased array: a Cartesian feedback approach.

In extending human MR to field strengths approaching 10 T, the wavelength of electromagnetic radiation at the proton Larmor frequency becomes less than human body size and conventional radio-frequency coil circumference. Consequently, radio-frequency magnetic fields are better generated by an array of small coils than by one large coil. In this article, the primary problem of array coil interactions during transmission is examined, and a standard proposed whereby secondary induced currents should be less than 1% of the primary coil current. The use of cancellation methods and of power amplifiers with high output impedance to reduce interactions is examined in the light of this standard and found wanting. Non-magnetic Cartesian feedback transceivers functioning at the magnet entrance are then proposed as a solution that both reduces instrumentation cost and increases the bandwidth over which the standard may be met. The compromises inherent in instrument design are detailed and examples given of the innovative circuitry used. It is shown experimentally that when connected to interacting coils, two Cartesian feedback instruments function stably in accord with theory and such that the proposed standard is typically attained over a bandwidth of 22 kHz during transmission (much greater during signal reception)—enough for all current MR protocols.

D.I. Hoult

Papers

The principle of reciprocity.

The quantum origins of the free induction decay signal and spin noise.

The NMR multi-transmit phased array: a Cartesian feedback approach.

Overcoming high-field RF problems with non-magnetic Cartesian feedback transceivers.

A 'Hi-Fi' Cartesian feedback spectrometer for precise quantitation and superior performance.