Systems analysis and simulation in ecology,vol. I, : edited by Bernard C. Patten 607 pages,diagrams, 6×9 in. Academic Press,New York, 1971. Price, $50.00 (approx).     

Robert J. Mulholland 《Journal of The Franklin Institute》1977,303(1):101-102

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Pole sensitivity in coupling networks     

Robert L. Koo  M. Sobral 《Journal of The Franklin Institute》1975,300(3):203-207

When designing lossless networks, one is faced with the problem of choosing a zero configuration for the reflection coefficient ?(s). Bode showed that if parasitic capacitances are present as well as for power transfer optimization, the best zero configuration is to locate all of them in the left half-plane. Recently, Bode's result was generalized to include parasitic immitances at both ends (source and load) of the quadripole.This work adds a new result to the theory by looking at the overall transfer function poles. It is shown that (a) if the source resistance varies, one should select left half-plane zeros for ?(s); and (b) if the load impedance varies, one should select right half-plane zeros.The pole sensitivity criterion used is the distance between the actual transfer function poles and the poles of the ideal transfer function.  相似文献   

The computation of discrimination values     

Robert G. Crawford 《Information processing & management》1975,11(8-12)

Results have been reported showing the usefulness of discrimination value in automatic construction of dictionaries for information retrieval. While discrimination value is defined in the literature, no specific explanation of its computation is given. In this paper the computation of discrimination value is discussed, a relatively efficient algorithm is presented and an example is given.  相似文献   

Technical change and social need: the case of high rise flats     

Robert McCutcheon 《Research Policy》1975,4(3):262-289

The first eleven storey blocks of flats in the UK were built in the early fifties. Only twenty years later over half a million people are housed in blocks varying from eleven to 31 storeys in height. These buildings have been built under the responsibility of public authorities responsible for the provision, management and maintenance of housing. Now, however, the provision of this type of housing has almost come to a halt. The widespread use of high flats has been seen as the inevitable result of advances in building technology. The recent rapid decline in numbers built has been attributed primarily to the concern arising from the inhuman social conditions which must inevitably result from such an unnatural form of housing. This paper argues that while high flats stemmed in part from technological advances, it is not possible to attribute their use to such advances. To do so ignores factors which were at work within national and local government, the building industry and the architectural profession. It is equally insufficient to attribute their decline to social concern. It is more probable that financial pressures and a change in national policy away from new building to restoration of older houses was of greater importance than the social problems created by high flats. However, one factor which helped to unite the various parties responsible for the introduction and use of high flats in housing policy, was a widespread belief in the possibilities of modern technologies in relation to the housing problem. Different aspects of the concept appealed to the different protagonists. This paper briefly describes some of the interactions between the different parties concerned with high flats. The major conclusion is that as an innovation high flats have not conformed to the theoretical postulates expounded about them, and that they have been greatly influenced by existing economic and social structures.  相似文献   

Evaluating the NASA small business innovation research program: preliminary evidence of a trade-off between commercialization and basic research     

Robert B Archibald  David H Finifter 《Research Policy》2003,32(4):605-619

In 1982, the Small Business Innovation Development Act established the small business innovation research (SBIR) program. This program reserves a percentage of federal agencies’ extramural R&D budgets for research projects conducted by small businesses. When this Act was reauthorized in 1992, the selection criteria for funding dramatically increased the likelihood of funding for projects that promised to lead to commercial success. Using data from a survey of the SBIR program award recipients at NASA Langley Research Center, we address three questions about this change: (i) was there a shift to projects with more commercial potential? (ii) did these projects experience higher rates of commercial success? and (iii) was there a reduction in basic research accompanying the increased commercial success? Our analysis suggests, the answer to all three of these questions is ‘yes’.  相似文献   

Text windows and phrases differing by discipline, location in document, and syntactic structure     

Robert M. Losee 《Information processing & management》1996,32(6):747-767

Knowledge of window style, content, location, and grammatical structure may be used to classify documents as originating within a particular discipline or may be used to place a document on a theory vs practice spectrum. This distinction is also studied here using the type-token ratio to differentiate between sublanguages. The statistical significance of windows is computed, based on the presence of terms in titles, abstracts, citations, and section headers, as well as binary-independent and inverse-document-frequency weightings. The characteristics of windows are studied by examining their within-window density and the S concentration, the concentration of terms from various document fields (e.g. title, abstract) in the fulltext. The rate of window occurrences from the beginning to the end of document fulltext differs between academic fields. Different syntactic structures in sublanguages are examined, and their use is considered for discriminating between specific academic disciplines and, more generally, between theory vs practice or knowledge vs applications-oriented documents.  相似文献   

Dynamic dictionary updating     

Robert G. Crawford 《Information processing & management》1977,13(4):235-245

A method for updating the dictionary in a dynamic information retrieval system is presented. It is shown that as a collection changes through addition and deletion of documents, the appropriate set of index terms may be determined without complete periodic regeneration of the dictionary. Results are presented for experiments involving a complete change in collection membership, with the dynamic dictionary updating methods shown to be effective.  相似文献   

Three Cases of Lead Toxicity Associated with Consumption of Ayurvedic Medicines     

Raviraja A  Vishal Babu GN  Sehgal A  Saper RB  Jayawardene I  Amarasiriwardena CJ  Venkatesh T 《Indian journal of clinical biochemistry : IJCB》2010,25(3):326-329

Ayurveda is a traditional form of medicine used by majority of the Indians. Here we report three cases of lead toxicity, following intake of Ayurvedic medicines. Three patients presented with blood lead levels (BLLs) of 122.4, 115 and 42.8 μg/dl respectively at the time of hospitalization. The first case was chelated with D- penicillamine, the second with calcium disodium ethylene diamino tetra acetate (EDTA) and the third with environmental intervention and education. Associated Ayurvedic products were collected from patients and analyzed for metallic concentration. Cessation of Ayurvedic medication along with chelation, nutritional intervention and education, reduced the BLL to 27.4 μg/dl in the first case after 1 year, 21.1 μg/dl after 9 months in the second and 18.2 μg/dl after 6 months in the third case.  相似文献   

Discoveries, When and By Whom?     

Hudson  Robert G. 《The British journal for the philosophy of science》2001,52(1):75-93

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Environmental jolts, institutional change, and the creation of entrepreneurial opportunity in the US electric power industry   总被引：1，自引：0，他引：1  

Wesley D Sine  Robert J David 《Research Policy》2003,32(2):185-207

The relationship between institutional change and entrepreneurship is poorly understood. We build the theory in this area by tracing institutional change in the US electric power industry over a 40-year period. Our analysis shows that environmental jolts mobilize actors to reformulate institutions, resulting in increased entrepreneurial opportunity. When the institutional environment is stable, we find that incumbent organizational forms and embedded logics present formidable obstacles to entrepreneurial activity. Environmental jolts, however, catalyze search processes and motivate the evaluation of current institutional logics. Specifically, in the case of the electric power industry, environments of abundance and regulation resulted in homogeneity of organizational structures and strategies, and few entrepreneurial opportunities. Environments marked by scarcity and crisis, however, witnessed heavy scrutiny of existing institutional arrangements that eroded their taken-for-grantedness and symbolic value, resulting in opportunities for entrepreneurial action.  相似文献