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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chinese Astronomy and Astrophysics 16 (1992), S. 124-132 
    ISSN: 0275-1062
    Keywords: Quantum cosmology-tunnelling wave function of the universe-conformal scalar
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2017-09-22
    Description: Compared with microscopic indices such as biomass, inverted satellite images can reflect cyanobacterial blooms from a macroscopic perspective, can provide planar information for blooms, and can more definitely reflect the occurrence of visible cyanobacterial blooms. We therefore adopted inverted images (from MODIS imagery) to judge whether cyanobacterial blooms had occurred in a water area at a given time. We constructed two probit models for identifying significant environmental factors related to cyanobacterial bloom occurrence and for short-term forecasts of bloom occurrence. The models used the index of cyanobacterial bloom occurrence as the dependent variable and the predicted variable, respectively, and used three categories (water quality, hydrology, and weather) of monitoring variables as the independent variables (or predictive variables). We used the Hill Dagong water area of Lake Tai in China as a case study of the new methods. The results produced by the identification model are consistent with the general conclusions in this research field indicating the validity of the model. The mean relative error of the forecast model is 13.5%, which is close to or lower than that of two previous models. Compared with the previous models, our forecast model also has advantages in terms of spatial and temporal precision. The new models have both practical applicability and the ability to be generalized and can, therefore, be easily adapted for the prevention, control, and prediction of cyanobacterial blooms in other bodies of water.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2023-09-12
    Description: Integrated three-dimensional seismic, logging, sediment cores, and geochemical testing data were collected from Guangzhou Marine Geological Survey 3 and 4 hydrate drilling expeditions and used in this study for a comprehensive investigation of the geological and geophysical features and accumulation mechanism of hydrates in the first offshore gas-hydrate production test region (GHPTR) in the Shenhu area of the South China Sea. Seismic signatures indicative of disseminated hydrates and free gas include the bottom simulating reflector (BSR), gas chimney, and mud diapir associated with enhanced seismic reflections, acoustic blanking, masking, and chaotic appearance have been observed. The acoustic travel-time responses, density, and compensated neutron three porosity log analysis, high-precision grid tomography inversion analysis, and constrained sparse spike inversion confirm the presence of free gas below the gas-hydrate-bearing zone (GHBZ). Free-gas-bearing zones have significantly different p-wave impedances and low-velocity anomalies than the overlying GHBZ and surrounding strata. These anomalous zones are controlled by the structural attitude of the reservoir strata, which are characterized as inter-bedded stratigraphic units. Variations in the type and geological characteristics of the hydrocarbon migration pathways were observed between sites W18 and W19 on the western ridge and sites W11 and W17 on the eastern ridge in the GMGS study area. The efficiency of gas migration in the western ridge may be higher than that in the eastern ridge, resulting in variations in hydrate gas types, thickness of the GHBZ, and gas migration flux and accumulation. Except for site W11, hydrates were recovered below the structure I inferred BSR at sites W17, W18, and W19. The gas-hydrate stability zone calculations reveal that the structure I hydrate stability zone differs from the BSR depth and is generally shallower than the base of the logging anomaly, indicating the coexistence of structure I and II hydrates. The BSR is not indicative of the BGHSZ; it is rather regarded as a transitional indicator of structure I and II gas hydrates in the GHPTR. The appearance of free gas and hydrates below the structure I inferred BSR indicates that the Shenhu area is characterized by a complex hydrate formation and accumulation system resulting from the supply of biogenic and thermogenic gases. Despite fine-grained host sediments predominating the GHPTR, the coupling of favorable conditions including efficient hydrocarbon generation, sufficient gas supply, multiple pathways for gas migration, and relatively high reservoir porosity have led to the development of highly saturated gas-hydrate accumulations within relatively thick sedimentary sections, which demonstrates a significant resource potential.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2023-09-12
    Description: Research on the formation and distribution of submarine channel systems and associated gas-bearing fluids is of great significance for gas hydrate exploration. Disseminated gas hydrates with high saturation up to 65% were recovered from a submarine ridge, equivalent to the levee of the channel–levee system in the Shenhu area, northern South China Sea. Sedimentary deposits in the submarine ridge were dominated by fine-grained silt and clay-rich silt; gas hydrates with relatively high saturation preferentially accumulated in coarser sediments with less clay content. Although abundant foraminifera fossils may have increased reservoir pore space, their presence was not a necessary condition for high-saturation hydrates. Higher levels of pyrite appeared in the reservoirs corresponding to high-saturation hydrates, which suggests that the reducing environment caused by sufficient methane provided adequate gas to form higher-saturation hydrates. Because of the migration of the channel–levee system, different channels formed their respective depositional systems composed of channel-filling, buried channel-filling, erosion grooves, and slumped turbidities. Relatively coarse-grained deposits were identified in the channel fillings and levees, and the accumulation of hydrates was affected by the lithological features of the sediments and their spatial coupling with the gas hydrate stability zone (GHSZ). GHSZ modeling based on in situ measurements indicated that erosion and sedimentation, as well as variations of the geothermal gradient, resulted in the upward/downward migration of bottom simulating reflectors (BSRs). On the erosion flank of the channel, the strata thinned, and rapid erosion was likely to destroy the shallower BSR, causing gas hydrate decomposition and methane release, and may have caused turbidite slumping and seepage, whereas the strata thickened on the deposition flank of the channel. The BSR in the channel–levee system would gradually move toward the new GHSZ, eventually forming a new BSR; parts of the BSR that formed under the original P–T conditions have remained, and double BSRs occurred in the seismic profile. The thermal fluid that moved upward through a gas chimney may also have caused the migration of the GHSZ, resulting in the emergence of double BSRs. During the lateral migration of the channel and the vertical migration of the gas-bearing fluid, there was a dynamic adjustment relationship between the GHSZ and the erosion–deposition process of the channel, resulting in the dynamic accumulation of hydrates in the Shenhu area. A model to demonstrate the relationship between channel migration and variation of the BSR was established, which is of great significance for understanding the formation and accumulation mechanisms of gas hydrates.
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2013-06-11
    Description: Background: To evaluate the peripapillary choroidal thickness of a healthy Chinese population, and to determine its influencing factors. Methods: A total of 76 healthy volunteers (76 eyes) without ophthalmic or systemic symptoms were enrolled. Choroidal scans (360-degree 3.4 mm diameter peripapillary circle scans) were obtained for all eyes using enhanced depth imaging spectral-domain optical coherence tomography. Choroid thickness was measured at the temporal, superotemporal, superior, superonasal, nasal, inferonasal, inferior, and inferotemporal segments. Results: The average peripapillary choroidal thicknesses were 165.03 +/- 40.37 mum. Inferonasal, inferior, and inferotemporal thicknesses were significantly thinner than temporal, superotemporal, superior, superonasal, nasal thicknesses (p 〈 0.05). No statistically significant difference was found among inferonasal, inferior, and inferotemporal thicknesses. The average peripapillary choroidal thickness decreased linearly with age (beta = -1.33, 95% CI -1.98, -0.68, P 〈 0.001). No correlation was noted between average choroidal thickness and other factors (gender, refractive error, axial length, average retinal nerve fiber layer thickness, intraocular pressure, diastolic blood pressure, systolic blood pressure, mean blood pressure, diastolic ocular perfusion pressure, systolic ocular perfusion pressure, and mean ocular perfusion pressure). Conclusions: The inferonasal, inferior, inferotemporal peripapillary choroidal thicknesses were significantly thinner than temporal, superotemporal, superior, superonasal, and nasal thicknesses. A thinner peripapillary choroid is associated with increasing age.
    Electronic ISSN: 1471-2415
    Topics: Medicine
    Published by BioMed Central
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  • 6
    Publication Date: 2013-06-27
    Description: Background: Eye diseases with increasing mortality are common health problems that affect people of all ages and demographic backgrounds. In this study, we study the publication characteristics in international ophthalmic journals of the US, the UK, Germany, Australia, Japan, and China. Methods: Articles published in 53 ophthalmic journals from 2000 to 2011 were retrieved from the PubMed database. We recorded the number of articles published each year, analyzed the publication type, and evaluated the accumulated and average impact factors (IFs), and the distribution of articles in ophthalmic journals in relation to IFs. The characteristics of publication outputs from China and other top-ranking countries were compared. Results: The total number of articles increased significantly during the past 12 years, with an increase of 51.0%. The growth in the annual number of articles from the US, the UK, Australia, and China showed a significantly positive trend. Publications from the US exceeded those from any other country and had the highest IFs, largest number of total citations of articles, and the most articles published in leading ophthalmic journals. During the past 12 years, China contributed 3.5% of the total publications, and the number of Chinese articles showed a more than 6-fold increase (from 99 to 605, R2 =0.947, P
    Electronic ISSN: 1471-2415
    Topics: Medicine
    Published by BioMed Central
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  • 7
    Publication Date: 2014-07-31
    Description: Background: Human bocavirus is a newly discovered parvovirus. Multiple studies have confirmed the presence of human bocavirus1 (HBoV1) in respiratory tract samples of children. The viral load, presentation of single detection and its role as a causative agent of severe respiratory tract infections have not been thoroughly elucidated. Methods: We investigated the presence of HBoV1 by quantitative polymerase chain reaction (PCR) of nasopharyngeal aspirate specimens from 1229 children hospitalized for respiratory tract infections. The samples were analyzed for 15 respiratory viruses by PCR and 7 respiratory viruses by viral culture. Results: At least one virus was detected in 652 (53.1%) of 1229 children, and two or more viruses were detected in 266 (21.6%) children. HBoV1 was detected in 127 children (10.3%), in which 66/127 (52%) of the cases was the only HBoV1 virus detected. Seasonal variation was observed with a high HBoV1 infection rate in summer. A cutoff value of 107 copies/mL was used to distinguish high and low HBoV1 viral loads in the nasopharyngeal aspirates. High viral loads of HBoV1 were noted predominantly in the absence of other viral agents (28/39, 71.8%) whereas there was primarily co-detection in cases of low HBoV1 viral loads (50/88, 56.8%). There were no differences in the clinical symptoms and severity between HBoV1 single detection and co-detection. In cases of HBoV1 single detection, the high viral load group was more prevalent among children with dyspnea and wheezing than was the low viral load group (42.9% vs. 23.7%, P = 0.036; 60.7% vs. 31.6%, P = 0.018). In clinical severity, a significant difference was recorded (25.0% vs. 5.3%, P = 0.003) between a high viral load and low viral load group. Of the HBoV1 positive patients associated with severe respiratory tract infections, 10/18 (55.6%) patients belonged to the HBoV1 high viral load group, and 7/10 (70%) patients had cases of HBoV1 single detection. Conclusions: HBoV1 at a high viral load is not frequently found in co-detection with other respiratory viruses, and a single detection with a high viral load could be an etiological agent of severe respiratory tract infections.
    Electronic ISSN: 1471-2334
    Topics: Medicine
    Published by BioMed Central
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  • 8
    Publication Date: 2015-01-18
    Description: Background: The association between heart failure (HF) and herpes zoster has rarely been studied. We investigated the hypothesis that HF may increase the risk of herpes zoster in Taiwan using a nationwide Taiwanese population-based claims database.MethodOur study cohort consisted of patients who received a diagnosis of HF in 2001?~?2009 (N?=?4785). For a comparison cohort, three age- and gender-matched control patients for every patient in the study cohort were selected using random sampling (N?=?14,355). All subjects were tracked for 1?year from the date of cohort entry to identify whether or not they had developed herpes zoster. Cox proportional-hazard regressions were performed to evaluate 1-year herpes zoster-free survival rates. Results: The main finding of this study was that patients with HF seemed to be at an increased risk of developing herpes zoster. Of the total patients, 211 patients developed herpes zoster during the 1-year follow-up period, among whom 83 were HF patients and 128 were in the comparison cohort. The adjusted hazard ratio (AHR) of herpes zoster in patients with HF was higher (AHR: 2.07; 95% confidence interval (CI): 1.54?~?2.78; p?
    Electronic ISSN: 1471-2334
    Topics: Medicine
    Published by BioMed Central
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  • 9
    Publication Date: 2015-05-09
    Description: Background: There is limited information on prevalent and incident atrial fibrillation in Chinese. We aimed to investigate the prevalence, incidence, management and risks of atrial fibrillation in an elderly Chinese population. Methods: In a population—based prospective study in elderly (≥60 years) Chinese, we performed cardiovascular health examinations including a 12-lead electrocardiogram at baseline in 3,922 participants and biennially during follow-up in 2,017 participants. We collected information on vital status during the whole follow-up period. Results: The baseline prevalence of atrial fibrillation was 2.0 % (n = 34) in 1718 men and 1.6 % (n = 36) in 2204 women. During a median 3.8 years of follow-up, the incidence rate of atrial fibrillation (n = 34) was 4.9 per 1000 person-years (95 % confidence interval [CI], 3.4–6.9). In univariate analysis, both the prevalence and incidence of atrial fibrillation were higher with age advancing (P 
    Electronic ISSN: 1471-2261
    Topics: Medicine
    Published by BioMed Central
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  • 10
    Publication Date: 2015-09-18
    Description: Background: To report the thickness of the retina, retinal ganglion cell (RGC)-related layers, and choroid in healthy subjects using swept source optical coherence tomography (SS-OCT). Methods: One hundred and forty-six healthy volunteers were consecutively recruited for this prospective observational study. Thickness of retina, RGC-related layers, and choroid in the standard early treatment of diabetic retinopathy study (ETDRS) grid were automatically measured using one SS-OCT (DRI OCT-1, Topcon, Japan). The IOL Master (Carl Zeiss Meditec, Germany) was used to measure axial length (AL). Results: Thicknesses of the average macular ganglion cell complex (GCC) and ganglion cell-inner plexiform layer (GCIPL) were 105.3 ± 9.7 and 78.5 ± 6.2 um respectively. Neither of them was significantly related with sex, age, or AL. Both showed strong correlations with retinal thickness (r = 0.793, p = 0.000; r = 0.813, p = 0.000, respectively) and with similar topographic distributions within the retina. The thicknesses of retina and GCC/GCIPL in the inner sectors were significantly higher than in the outer sectors of the EDTRS area, while in the same region of the macula, the choroid exhibited completely different patterns of topographic variation. Men had 7.8 um thicker retina and 34.9 um thicker choroid than women after adjustment for age and AL (all p 
    Electronic ISSN: 1471-2415
    Topics: Medicine
    Published by BioMed Central
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