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  • 1
    ISSN: 1420-9136
    Keywords: Key Words: Taiwan, crustal structure, receiver functions.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —Receiver function analysis is used to determine local crustal structure beneath Taiwan. We have performed preliminary data processing and polarization analysis for the selection of stations and events and to increase overall data quality. Receiver function analysis is then applied to data from the Taiwan Seismic Network to obtain radial and transverse receiver functions. Due to the limited azimuthal coverage, only the radial receiver functions are analyzed in terms of horizontally layered crustal structure for each station. In order to improve convergence of the receiver function inversion, frequency-band inversion (FBI) is implemented, in which an iterative inversion procedure with sequentially higher low-pass corner frequencies is used to stabilize the waveform inversion. Frequency-band inversion is applied to receiver functions at six stations of the Taiwan Seismic Network. Initial 20-layer crustal models are inverted for using prior tomographic results for the initial models. The resulting 20-1ayer models are then simplified to 4 to 5 layer models and input into an alternating depth and velocity frequency-band inversion. For the six stations investigated, the resulting simplified models provide an average estimate of 38 km for the Moho thickness surrounding the Central Range of Taiwan. Also, the individual station estimates compare well with the recent tomographic model of and the refraction results of Rau and Wu (1995) and the refraction results of Ma and Song (1997).
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  • 2
    ISSN: 1420-9136
    Keywords: Key words: Seismic attenuation, seismic Q, Midcontinent rift.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —Instantaneous frequency matching has been used to compute differential t* values for seismic reflection data from the Great Lakes International Multidisciplinary Program on Crustal Evolution (GLIMPCE) experiment. The differential attenuation values were converted to apparent Q −1 models by a fitting procedure that simultaneously solves for the interval Q −1 values using non-negative least squares. The bootstrap method was then used to estimate the variance in the interval Q −1 models. The shallow Q −1 structure obtained from the seismic reflection data corresponds closely with an attenuation model derived using instantaneous frequency matching on seismic refraction data along the same transect. This suggests that the effects of wave propagation and scattering on the apparent attenuation are similar for the two data sets. The Q −1 model from the reflection data was then compared with the structural interpretation of the reflectivity data. The highest interval Q −1 values (〉0.01) were found near the surface, corresponding to the sedimentary rock sequence of the upper Keweenawan. Low Q −1 values (〈0.0006) are found beneath the Midcontinent rift’s central basin. In addition to structural interpretation, seismic attenuation models derived in this way can be used to correct reflection data for dispersion, frequency and amplitude effects, and allow for improved imaging of the subsurface.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A soluble form of the complement receptor CD21 (sCD21) is shed from the lymphocyte surface. The amount of sCD21 in serum may modulate immunity as sCD21 levels are correlated with several clinical conditions. We report here the serum levels of sCD21 in juvenile arthritis (JA), systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS). Using enzyme-linked immunosorbent assay, we determined sCD21 levels in SLE, SS and JA patients. Mann–Whitney test for nonparametric two-tail P value was performed to obtain statistical significance. Cytometrical analysis of synovial fluid leucocytes of JA patients was done on a FACSsort. While sCD21 levels in SLE and SS are reduced to levels previously found in rheumatoid arthritis (RA), JA sCD21 levels were normal. sCD21 levels did not correlate with clinical parameters and immunophenotype of synovial cells. CD4 T cells in the synovium were almost all of the CD45RO memory type and 13 of 40 patients displayed synovial expansion of γδT cells. CD21 shedding in JA differs from RA/SS/SLE. JA sCD21 levels in synovial fluid are always lower compared to blood levels of the same patients. Analysis of JA synovial T cells indicates a T-cell driven response.
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  • 4
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of cytoplasmic anti-neutrophil cytoplasm autoantibodies (C-ANCA) and perinuclear ANCA (P-ANCA) immunoglobulin G (IgG) on tissue factor (TF) activity using HL-60 cells in vitro were compared with those of medium, lipopolysaccharide (LPS) and control IgG. Cells were also incubated with both ANCA IgG and control IgG in the presence of a submaximal concentration of LPS capable of upregulating TF procoagulant activity (TF-PCA) measured in arbitrary units of TF equivalent (AU-TFEq). The purpose was to search for an additive effect between LPS and ANCA IgG. All IgG preparations increased HL-60 cell TF-PCA in comparison with the medium. When cells were incubated with P-ANCA IgG and LPS (1 µg/ml), a larger increase was seen (151.23 ± 31.6 SEM (standard error of the mean) AU-TFEq) than when incubated with control IgG plus LPS (91.01 ± 18.4 SEM AU-TFEq; P 〈 0.005), P-ANCA IgG alone (73.68 ± 12.7 SEM AU-TFEq; P 〈 0.005) or LPS (1 µg/ml) (58.11 ± 7.9 SEM AU-TFEq; P 〈 0.005). There was concordance between PCA and TF total antigen content by enzyme-linked immunosorbent assay (ELISA). The fact that P-ANCA IgGs upregulate the function of TF in HL-60 cells in combination with LPS adds to information regarding the possible role of ANCAs in the enhancement of TF by different cells, although it does not support the fact that ANCAs alone play a role in mononuclear cell TF upregulation. The additive effects of LPS underline the possible role of pro-inflammatory stimuli in the pathogenesis of ANCA-associated diseases.
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  • 5
    ISSN: 1432-1440
    Keywords: Angiotensin-converting enzyme inhibitors ; Cilazapril ; Furosemide ; Natriuresis ; Antinatriuresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The goal of this study was to quantitate the effect of angiotensin-converting enzyme inhibition on renal sodium handling after furosemide injection. The study was carried out on low and normal salt intake to assess potential interaction with salt balance. Eighteen healthy normotensive volunteers were examined in a double placebo-controlled parallel group design. Subjects were randomly put on either low-salt (20 mmol/day) or normal-salt (110 mmol/day) diet. In either arm of the diet volunteers were first treated orally with placebo for 1 week and subsequently with 2.5 mg/day of the angiotensin-converting enzyme inhibitor cilazapril for another 1 week. Cumulative 24-h urinary sodium excretion was measured on the 6th day of the respective week after sham injection and on the 7th day after injection of 40 mg furosemide. Compared to pretreatment with placebo, pretreatment with cilazapril resulted in a higher cumulative sodium excretion after furosemide injection (day 7) than after the sham injection (day 6) on both salt intakes. The difference in natriuresis (cilazapril versus placebo) was evident 2 and 3 h after injection of furosemide. Neither the time of onset nor the magnitude of antinatriuresis were affected by cilazapril. Following furosemide angiotensin II increased significantly even after cilazapril pretreatment. Cilazapril tended to reduce urinary furosemide excretion. At any given urinary furosemide concentration, the increment in urinary sodium excretion was significantly greater with cilazapril irrespective of salt intake. The study shows that (a) cilazapril increases furosemide-induced natriuresis irrespective of salt intake, (b) antinatriuresis is not affected by cilazapril, and (c) angiotensin II levels rise after furosemide on cilazapril in therapeutic doses.
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  • 6
    ISSN: 1432-1440
    Keywords: Thiazides ; Glomerular filtration ; Hemoconcentration ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To elucidate the renal effects of thiazides as a function of sodium intake, 8 healthy volunteers without renal disease were studied at baseline and 1 day as well as 4 days after the administration of 100 mg hydrochlorothiazide/day. The subjects were compared on two different dietary sodium intakes (120 mmol/day and 220 mmol/day). Measurements comprised inulin clearance (Cin) and paraaminohippurate clearance (Cpah) by infusion clearance technique, total and ionised calcium, immunoreactive parathyroid hormone (1,84 iPTH), 1.25 (OH)2 vitamin D3, and indices of hemoconcentration. Acute administration of hydrochlorothiazide (HCTZ) caused no change in Cin (before 111 ± 3 ml/min 1.73 m2 ; 24 h after, 107 ± 2 ml/min 1.73 m2) or Cpah (before, 579 ± 9 ml/min 1.73 M2; after, 584 ± 12 ml/min 1.73 m2), while a significant (P 〈 0.01) decrease was noted on the 4th day after 100 mg HCTZ/day and normal sodium intake. No significant change of creatinine clearance (Ccr) was seen with either manouever. Renal hemodynamic changes after HCTZ administration were marginal when hemoconcentration was prevented by a high salt intake. Acute administration (1 h) of HCTZ caused suppression of 1,84 iPTH (before, 2.3 ±0.5 pmol/l; after, 1.9 ± 0.2 pmol/l; P 〈 0.01), but after 4 days a lower ionised calcium (baseline, 1.25 ± 0.01 mmol/l; day 5, 1.20 ± 0.02 mmol/l; P 〈 0.01) was noticed in parallel with hemoconcentration, metabolic alkalosis, and reduced 1,25 (OH)2 vitamin D3 concentrations. The level of 1,84 iPTH was elevated. We conclude that (i) hydrochlorothiazide does not affect the renal hemodynamics if hemoconcentration is avoided and (ii) hydrochlorothiazide acutely lowers PTH, while subacutely metabolic alkalosis and decreased ionised calcium may occur with concomitant increase in 1,84 iPTH and decrease in 1,25 (OH)2 vitamin D3 concentrations unless hemoconcentration is prevented.
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