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General Circulation (general + circulation)

Distribution by Scientific Domains
Earth and Environmental Science62%
Medical Sciences37%

Terms modified by General Circulation

  • general circulation model
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  • general circulation models
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    Selected Abstracts

    Response of the summer atmospheric circulation over East Asia to SST variability in the tropical Pacific

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2010
    Rena Nagata
    Abstract General circulation over East Asia and its linkages with sea surface temperature (SST) variability over the tropical Pacific is investigated for the 1958,2000 period. The western edge of the North Pacific subtropical high (NPSH) index (SHI) is defined from pentad 31 (May 31 to June 4) to pentad 49 (August 29 to September 2). A southwestward extension of the SHI has been observed since 1980. The changes in the NPSH are associated with SST warming in the tropical eastern Pacific and Indian Ocean. On the basis of the SHI, years with western, eastern, southern and northern displacement of the NPSH are defined as WD, ED, SD and ND years. WD and SD years occur after 1980. Climatologically, the subsidence is located around 30°N in the western Pacific. This subsidence area corresponds to the NPSH region. Before pentad 40 in WD and SD years, associated with warm SST anomalies, circulation anomalies show an ascending motion over the tropical eastern Pacific and Indian Ocean. This ascending motion induces the anomalous subsidence over the tropical western Pacific and causes the southwestward extension of the NPSH. After pentad 40 (July 15,19), the seasonal evolution of WD years is different from the SD years. After pentad 40 in WD years, associated with large warm SST anomalies over the tropical eastern Pacific and Indian Ocean, the strong anomalous ascending motion strengthens the anomalous subsidence in the western tropical Pacific and leads to the lack of the eastward contraction of the NPSH. In SD years, warm SST anomalies over the tropical eastern Pacific and Indian Ocean weakened after pentad 40. Correspondently, the weakened anomalous ascending motion over these regions provides the weak anomalous subsidence over the tropical western Pacific. The weakened anomalous subsidence leads to the eastward contraction of the NPSH after pentad 40 similar to the climatological evolution. Copyright © 2009 Royal Meteorological Society [source]

    Recent advances in understanding the circulation and hydrography of the East China Sea

    FISHERIES OCEANOGRAPHY, Issue 6 2002
    Heung-Jae Lie
    Abstract The physical oceanography of the East China Sea (ECS) has been studied extensively through comprehensive observing programmes conducted in the 1990s, allowing clarification of the major oceanographic processes involved in establishing the hydrography and circulation. An overview of the general circulation and hydrography in the ECS is given here, mainly based on the new observational results and with special attention to the Kuroshio bifurcation north-east of Taiwan and south-west of Kyushu and the major currents in the outer continental shelf. A new schematic circulation pattern of the ECS is sketched using these observations. The oceanographic conditions and fisheries environments of the ECS are not only seasonally variable because of the response of the basin to the seasonally varying atmospheric conditions, but also spatially and temporally complicated because of the wide spectrum of phenomena that coexist with various scales. [source]

    Circulating EM66 is a highly sensitive marker for the diagnosis and follow-up of pheochromocytoma

    INTERNATIONAL JOURNAL OF CANCER, Issue 8 2006
    Johann Guillemot
    Abstract We have previously demonstrated that measurement of tissue concentration of the novel secretogranin II-derived peptide EM66 may help to discriminate between benign and malignant pheochromocytomas. The aim of the present study was to characterize EM66 in plasma and urine of healthy volunteers and pheochromocytoma patients, in order to further evaluate the usefulness of this peptide as a circulating marker for the management of the tumors. HPLC analysis of plasma and urine samples demonstrated that the EM66-immunoreactive material coeluted with the recombinant peptide. In healthy volunteers, plasma and urinary EM66 levels were, respectively, 2.6 (1.9,3.7) ng/ml and 2.9 (1.9,4.6) ng/ml. In patients with pheochromocytoma, plasma EM66 levels were 10-fold higher than those of healthy volunteers (26.9 (7.3,44) ng/ml), and returned to normal values after removal of the tumor. In contrast, urinary EM66 levels were not significantly different from those of healthy volunteers (3.2 (2.2,3.9) ng/ml). Measurement of total or free plasma metanephrines and 24 hr urinary metanephrines in our series of patients revealed that these tests, taken separately, are less sensitive than the EM66 determination. Pheochromocytes in primary culture secreted high levels of EM66, suggesting that the chromaffin tumor was actually responsible for the increased plasma peptide concentrations in the patients. These data indicate that EM66 is secreted in the general circulation and that elevated plasma EM66 levels are correlated with the occurrence of pheochromocytoma. Thus, EM66 is a sensitive plasma marker that should be considered as a complementary tool in the management of pheochromocytoma. © 2005 Wiley-Liss, Inc. [source]

    A statistical downscaling method for monthly total precipitation over Turkey

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2004
    Hasan Tatli
    Abstract Researchers are aware of certain types of problems that arise when modelling interconnections between general circulation and regional processes, such as prediction of regional, local-scale climate variables from large-scale processes, e.g. by means of general circulation model (GCM) outputs. The problem solution is called downscaling. In this paper, a statistical downscaling approach to monthly total precipitation over Turkey, which is an integral part of system identification for analysis of local-scale climate variables, is investigated. Based on perfect prognosis, a new computationally effective working method is introduced by the proper predictors selected from the National Centers for Environmental Prediction,National Center for Atmospheric Research reanalysis data sets, which are simulated as perfectly as possible by GCMs during the period of 1961,98. The Sampson correlation ratio is used to determine the relationships between the monthly total precipitation series and the set of large-scale processes (namely 500 hPa geopotential heights, 700 hPa geopotential heights, sea-level pressures, 500 hPa vertical pressure velocities and 500,1000 hPa geopotential thicknesses). In the study, statistical preprocessing is implemented by independent component analysis rather than principal component analysis or principal factor analysis. The proposed downscaling method originates from a recurrent neural network model of Jordan that uses not only large-scale predictors, but also the previous states of the relevant local-scale variables. Finally, some possible improvements and suggestions for further study are mentioned. Copyright © 2004 Royal Meteorological Society [source]

    Changes in the sub-decadal covariability between Northern Hemisphere snow cover and the general circulation of the atmosphere

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2004
    Kazuyuki Saito
    Abstract Details of the sub-decadal covariability relationship between continental snow cover extent anomalies and the dominant mode of atmospheric variability, referred to as the Arctic oscillation (AO) or North Atlantic oscillation (NAO), for the period 1971,2001 are explored. On the seasonal time scale, the winter AO is found to be significantly correlated with the preceding autumn Eurasian snow cover (SNCEUR) throughout the period observed. Consistent with this finding, SNCEUR variability led the AO variability on the sub-decadal time scale in the early half of the record. However, starting in the mid 1980s, the AO and SNCEUR vary in phase. Analyses of the seasonal relationship and persistence of snow and atmospheric variables illustrate a phase shift in the sub-decadal variability between the AO and SNCEUR due to the loss of autumn,winter SNCEUR autocorrelation replaced by a significant winter,spring persistence and the emergence of a concurrent SNCEUR,AO connection in winter and spring. Similar analysis shows that the sub-decadal NAO variation is mostly described by the fluctuation in summer North American snow cover. Copyright © 2004 Royal Meteorological Society [source]

    Intra-seasonal rainfall characteristics and their importance to the seasonal prediction problem

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2002
    Warren J. Tennant
    Abstract Daily station rainfall data in South Africa from 1936 to 1999 are combined into homogeneous rainfall regions using Ward's clustering method. Various rainfall characteristics are calculated for the summer season, defined as December to February. These include seasonal rainfall total, region-average number of station rain days exceeding 1 and 20 mm, region-average of periods between rain days at stations >1 and >20 mm, region-average of wet spell length (sequential days of station rainfall >1 and >20 mm), correlation of daily station rainfall within a region and correlation of seasonal station rainfall anomalies within a region. Rank-ordered rainfall characteristic data generally form an s-shaped curve, and significance testing of discontinuities in these curves suggests that normal rainfall conditions in South Africa consist of a combined middle three quintiles separated from the outer quintiles, rather than the traditional middle tercile. The relationships between the various rainfall characteristics show that seasons with a high total rainfall generally have a higher number of heavy rain days (>20 mm) and not necessarily an increase in light rain days. The length of the period between rain days has a low correlation to season totals, demonstrating that seasons with a high total rainfall may still contain prolonged dry periods. These additional rainfall characteristics are important to end-users, and the analysis undertaken here offers a valuable starting point for seeking physical relationships between rainfall characteristics and the general circulation. Preliminary studies show that the vertical mean wind is related to rainfall characteristics in South Africa. Given that general circulation models capture this part of the circulation adequately, seasonal forecasts of rainfall characteristics become plausible. Copyright © 2002 Royal Meteorological Society. [source]

    Intracerebral monitoring in comatose patients treated with hypothermia after a cardiac arrest

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2009
    J. NORDMARK
    Background: Induced mild hypothermia (32,34 °C) has proven to reduce ischemic brain injury and improve outcome after a cardiac arrest (CA). The aim of this investigation was to study the occurrence of increased intracranial pressure (ICP) and neurochemical metabolic changes indicating cerebral ischemia, after CA and cardiopulmonary resuscitation (CPR), when induced hypothermia was applied. Methods: ICP, brain chemistry and brain temperature were monitored during induced hypothermia and re-warming in four adult unconscious patients with restoration of spontaneous circulation after CA and CPR. Results: ICP was occasionally above 20 mmHg. Neurochemical changes indicating cerebral ischemia (increased lactate/pyruvate ratio) and excitoxicity (increased glutamate) were found after CA, and signs of ischemia were also observed during the re-warming phase. A biphasic increase in glycerol was seen, which may have been a result of both membrane degradation and overspill from the general circulation. Conclusions: Intracerebral microdialysis and ICP monitoring may be used in selected patients not requiring anticoagulants and PCI to obtain information regarding the common disturbances of intracranial dynamics after CA. The results of this study underline the importance of inducing hypothermia quickly after CA and emphasize the need for developing tools for guidance of the re-warming. [source]

    Gene therapy for diseases of the cornea , a review

    CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2010
    Keryn A Williams PhD
    Abstract The cornea is particularly suited to gene therapy. The cornea is readily accessible, normally transparent, and is somewhat sequestrated from the general circulation and the systemic immune system. The principle of genetic therapy for the cornea is to use an appropriate vector system to transfer a gene to the cornea itself, or to the ocular environs, or systemically, so that a transgenic protein will be expressed that will modulate congenital or acquired disease. The protein may be structural such as a collagen, or functionally active such as an enzyme, cytokine or growth factor that may modulate a pathological process. Alternatively, gene expression may be silenced by the use of modalities such as antisense oligonucleotides. Interestingly, despite a very considerable amount of work in animal models, clinical translation directed to gene therapy of the human cornea has been minimal. This is in contrast to gene therapy for monogenic inherited diseases of the retina, where promising early results of clinical trials for Leber's congenital amaurosis have already been published and a number of other trials are ongoing. [source]