42,886 research outputs found

    An algorithm to generate input data from meteorological and space shuttle observations to validate a CH4-CO model

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    Objective procedures to analyze data from meteorological and space shuttle observations to validate a three dimensional model were investigated. The transport and chemistry of carbon monoxide and methane in the troposphere were studied. Four aspects were examined: (1) detailed evaluation of the variational calculus procedure, with the equation of continuity as a strong constraint, for adjustment of global tropospheric wind fields; (2) reduction of the National Meteorological Center (NMC) data tapes for data input to the OSTA-1/MAPS Experiment; (3) interpolation of the NMC Data for input to the CH4-CO model; and (4) temporal and spatial interpolation procedures of the CO measurements from the OSTA-1/MAPS Experiment to generate usable contours of the data

    Why will rat's go where rats will not

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    Experimental evidence indicates that regular plurals are nearly always omitted from English compounds (e.g., rats-eater) while irregular plurals may be included within these structures (e.g., mice-chaser). This phenomenon is considered to be good evidence to support the dual mechanism model of morphological processing (Pinker & Prince, 1992). However, evidence from neural net modelling has shown that a single route associative memory based account might provide an equally, if not more, valid explanation of the compounding phenomenon

    Plural morphology in compounding is not good evidence to support the dual mechanism model

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    The compounding phenomena is considered to be good evidence to support the dual mechanism model of morphological processing (Pinker & Prince, 1992). However evidence from initial neural net modeling has shown that a single route associative memory based account might provide an equally, if not more valid explanation of the treatment of plurals in compounds. Further neural net modeling and empirical work is proposed to test this single route accoun

    The Arizona Radio Observatory CO Mapping Survey of Galactic Molecular Clouds: III. The Serpens Cloud in CO J=2-1 and 13CO J=2-1 Emission

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    We mapped 12CO and 13CO J = 2-1 emission over 1.04 square deg of the Serpens molecular cloud with 38 arcsec spatial and 0.3 km/s spectral resolution using the Arizona Radio Observatory Heinrich Hertz Submillimeter telescope. Our maps resolve kinematic properties for the entire Serpens cloud. We also compare our velocity moment maps with known positions of Young Stellar Objects (YSOs) and 1.1 mm continuum emission. We find that 12CO is self-absorbed and 13CO is optically thick in the Serpens core. Outside of the Serpens core, gas appears in filamentary structures having LSR velocities which are blue-shifted by up to 2 km/s relative to the 8 km/s systemic velocity of the Serpens cloud. We show that the known Class I, Flat, and Class II YSOs in the Serpens core most likely formed at the same spatial location and have since drifted apart. The spatial and velocity structure of the 12CO line ratios implies that a detailed 3-dimensional radiative transfer model of the cloud will be necessary for full interpretation of our spectral data. The starless cores region of the cloud is likely to be the next site of star formation in Serpens.Comment: 41 pages, 15 figure

    Space physics analysis network node directory (The Yellow Pages): Fourth edition

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    The Space Physics Analysis Network (SPAN) is a component of the global DECnet Internet, which has over 17,000 host computers. The growth of SPAN from its implementation in 1981 to its present size of well over 2,500 registered SPAN host computers, has created a need for users to acquire timely information about the network through a central source. The SPAN Network Information Center (SPAN-NIC) an online facility managed by the National Space Science Data Center (NSSDC) was developed to meet this need for SPAN-wide information. The remote node descriptive information in this document is not currently contained in the SPAN-NIC database, but will be incorporated in the near future. Access to this information is also available to non-DECnet users over a variety of networks such as Telenet, the NASA Packet Switched System (NPSS), and the TCP/IP Internet. This publication serves as the Yellow Pages for SPAN node information. The document also provides key information concerning other computer networks connected to SPAN, nodes associated with each SPAN routing center, science discipline nodes, contacts for primary SPAN nodes, and SPAN reference information. A section on DECnet Internetworking discusses SPAN connections with other wide-area DECnet networks (many with thousands of nodes each). Another section lists node names and their disciplines, countries, and institutions in the SPAN Network Information Center Online Data Base System. All remote sites connected to US-SPAN and European-SPAN (E-SPAN) are indexed. Also provided is information on the SPAN tail circuits, i.e., those remote nodes connected directly to a SPAN routing center, which is the local point of contact for resolving SPAN-related problems. Reference material is included for those who wish to know more about SPAN. Because of the rapid growth of SPAN, the SPAN Yellow Pages is reissued periodically

    The natural history of metastasis of syngeneic murine squamous carcinoma and the prognostic implications of primary tumour size and duration of growth.

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    A study has been made of the natural history of metastasis of a spontaneous murine squamous carcinoma implanted into syngeneic recipients--a situation where biologically different tumours and variable "host resistance" are not complicating issues. The time distrubution of deaths from metastatic disease was incompatible with a log-normal distribution but was accurately described by an exponential pattern of survival following an initial lag. While the average life of doomed mice correlated with predictions based on growth rates, there was a wide range of survival times indicating random influences on the evolution of metastitic disease. Insofar as tumours which grew to 20 mm3 or less in 5 days after tumour cell injection failed to initiate metastases, while tumours which reached a size of 120 mm3 or greater (irrespective of duration) produced metastases in 38/39 mice, tumour size was a prognostic index. However, within the size range 33-150 mm3 the correlation between metastatic risk and size was not statistically significant. No correlation between metastatic risk and duration of tumour growth from 6 to 29 days was observed. Two integral functions of tumour size and duration were tested but neither gave a better correlation with metastatic risk than did size alone

    A study of the influence of various diagnostic and therapeutic procedures applied to a murine squamous carcinoma on its metastatic behaviour.

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    An experimental tumour system for the study of metastasis has been developed using a syngeneically transplanted murine squamous carcinoma of spontaneous origin. Implants of the tumour, which does not elicit a significant immune response, grew and metastasized regularly to regional lymph nodes and lungs, in a manner comparable with that of the more malignant types of human epithelioma. The system has been used to test the influece of pre-operative irradiation, regional lymph node excision, tumour biopsy and manipulation, on metastasis. Of these, only pre-operative irradiation with 2000 rad 24 h before tumour excision produced a significant differential effect--a lower incidence of metastasis. By contrast, local radiation therapy sufficient to cause complete tumour regression but insufficient to achieve long-term local cure was shown to result in accelerated metastasis. A highly significant inhibition of metastasis was observed with the drug ICRF 159, but histological features suggested that its anti-metastatic effect in this system did not depend on morphological changes which might prevent dissemination of tumour cells

    Enhancement of syngeneic murine tumour transplantability by whole body irradiation--a non-immunological phenomenon.

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    Experiments were undertaken to test the general validity of the assumption that potentiation of tumour transplantability by sublethal whole body irradiation (WBI) implies some degree of immunological resistance in the intact host. A transplantable carcinoma of spontaneous origin in CBA mice which exhibits a large WBI effect was assayed quantitatively in mice which had been immunologically crippled in terms of allograft acceptance by depletion of thymus derived lymphocytes. The mean number of tumour cells required for 50% successful takes (TD50) in these mice was found to be not significantly different from that in normal controls but highly significantly greater than in WBI mice. On the other hand, in mice which underwent laparotomy immediately before assay, the TD50 was reduced significantly though not to the same extent as in WBI mice. It was concluded that WBI effect was not due to impaired host immunity but possibly to physiological changes resulting from acute stress. The hypothesis that hyperfibrinogenaemia which occurs after both WBI and laparotomy might increase tumour transplantability was rejected because of the lack of correlation between TD50 and fibrinogen levels at different times after each procedure. From this and other work it is apparent that TD50 data, in themselves, give no reliable indication of host immunity

    Feasibility study of silicon nitride protection of plastic encapsulated semiconductors

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    The application of low temperature silicon nitride protective layers on wire bonded integrated circuits mounted on lead frame assemblies is reported. An evaluation of the mechanical and electrical compatibility of both plasma nitride and photochemical silicon nitride (photonitride) passivations (parallel evaluations) of integrated circuits which were then encapsulated in plastic is described. Photonitride passivation is compatible with all wire bonded lead frame assemblies, with or without initial chip passivation. Plasma nitride passivation of lead frame assemblies is possible only if the chip is passivated before lead frame assembly. The survival rate after the environmental test sequence of devices with a coating of plasma nitride on the chip and a coating of either plasma nitride or photonitride over the assembled device is significantly greater than that of devices assembled with no nitride protective coating over either chip or lead frame

    Smoking, dementia and cognitive decline in the elderly, a systematic review.

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    Background. Nicotine may aid reaction time, learning and memory, but smoking increases cardiovascular risk. Cardiovascular risk factors have been linked to increased risk of dementia. A previous meta-analysis found that current smokers were at higher risk of subsequent dementia, Alzheimers disease, vascular dementia and cognitive decline. Methods. In order to update and examine this further a systematic review and meta-analysis was carried out using different search and inclusion criteria, database selection and more recent publications. Both reviews were restricted to those aged 65 and over. Results. The review reported here found a significantly increased risk of Alzheimers disease with current smoking and a likely but not significantly increased risk of vascular dementia, dementia unspecified and cognitive decline. Neither review found clear relationships with former smoking. Conclusion. Current smoking increases risk of Alzheimers disease and may increase risk of other dementias. This reinforces need for smoking cessation, particularly aged 65 and over. Nicotine alone needs further investigation. © 2008 Peters et al; licensee BioMed Central Ltd
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