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- Ståhl, Bertil, 1957-
(författare)
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Theophrastaceae
- 2001
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Ingår i: Flora de Nicaragua. - St. Louis : Missouri Botanical Garden Press. - 0915279959 ; , s. 2448-2450
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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- Monterroso, David A., et al.
(författare)
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Spatial variations of b-value in the subduction zone of Central America
- 2003
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Ingår i: Geofísica Internacional. - 0016-7169. ; 42:4, s. 575-587
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Tidskriftsartikel (refereegranskat)abstract
- requency-magnitude distribution along the Mid-American Trench (MAT) has been studied by means of 2345 earthquakesduring the period 1964-1994. We used the regional MIDAS catalogue with a magnitude of completeness of 4.2. To resolve the bvalueas a function of depth (one dimensional approach), we applied vertically sliding windows containing a constant number ofevents. To obtain more details in the b distribution, we projected catalogue hypocenters in three selected regions (approximatelyGuatemala and El Salvador, Nicaragua, Costa Rica), onto planes perpendicular to the trench. The b-values were calculated insliding cylindrical volumes (two-dimensional approach) containing a constant number of earthquakes and centered at nodes of a5 km x 5 km grid. The b-value varies significantly along a large part of MAT. High b-values were identified in the upper part of theslab at depths of 80-110 km beneath Guatemala-El Salvador and at depths 130-170 km beneath Nicaragua. Anomalous (high) bvaluesin the lower part of the slab were located at depths of 50-90 km and 50-160 km beneath Guatemala-El Salvador andNicaragua, respectively. Anomalies observed at the upper part of the slab may be related to dehydration and successive increase inpore pressure in the down-going lithosphere, which may generate volcanism above the anomalies in the upper part of the slab.Anomalies on the lower surface of the Wadati-Benioff zone are likely to be associated with high thermal gradients between theslab and mantle.
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- Lovmar, Lovisa, 1977-
(författare)
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Methods for Analysis of Disease Associated Genomic Sequence Variation
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Molecular Medicine a wide range of methods are applied to analyze the genome to find genetic predictors of human disease. Apart from predisposing disease, genetic variations may also serve as genetic markers in the search for factors underlying complex diseases. Additionally, they provide a means to distinguish between species, analyze evolutionary relationships and subdivide species into strains. The development and improvement of laboratory techniques and computational methods was a spin-off effect of the Human Genome Project. The same techniques for analyzing genomic sequence variations may be used independent of organism or source of DNA or RNA. In this thesis, methods for high-throughput analysis of sequence variations were developed, evaluated and applied. The performance of several genotyping assays were investigated prior to genotyping 4000 samples in a co-operative genetic epidemiological study. Sequence variations in the estrogen receptor alpha gene were found to be associated with an increased risk of breast and endometrial cancer in Swedish women.Whole genome amplification (WGA) enables large scale genetic analysis of sparse amounts of biobanked DNA samples. The performance of two WGA methods was evaluated using four-color minisequencing on tag-arrays. Our in-house developed assay and “array of arrays” format allow up to 80 samples to be analyzed in parallel on a single microscope slide. Multiple displacement amplification by the Φ29 DNA polymerase gave essentially identical genotyping results as genomic DNA. To facilitate accurate method comparisons, a cluster quality assessment approach was established and applied to assess the performance of four commercially available DNA polymerases in the tag-array minisequencing assay. A microarray method for genotyping human group A rotavirus (HRV) was developed and applied to an epidemiological survey of infectious HRV strains in Nicaragua. The method combines specific capture of amplified viral sequences on microarrays with genotype-specific DNA-polymerase mediated extension of capture oligonucleotides with fluorescent dNTPs.
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- Monterroso Juárez, David Aníbal, 1971-
(författare)
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Statistical Seismology Studies in Central America : b-value, seismic hazard and seismic quiescence
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present thesis collects results of research applying theory and methods of statistical seismology to the seismicity of Central America, a region with a complex tectonic setting controlled by the interaction of four major plates, namely the Caribbean, Cocos, Nazca and North American plates.Three different earthquake catalogues were used for studies focused on stress in a tectonic volume, seismic hazard maps and seismicity patterns (precursors), covering the region 94ºW to 81ºW and 5ºN to 20ºN.Variations in the b-value, the parameter in Gutenberg & Richter’s equation LogN=a-bM, as a function of depth in the subduction zone were investigated. High b-values were identified in the upper part of the slab at depths of 80-110km beneath Guatemala-El Salvador and at depths 130-170km beneath Nicaragua. These anomalies may be related to the generation of volcanism occurring above them. Time dependence of the b-value was also studied. Five case studies were selected (events with MS ≥7.2) for a detailed analysis. In three out of five cases, it was possible to link b-value minima to the time of occurrence of corresponding large events.Seismic quiescence was mapped as a function of time and space by a griding technique. The characteristics of the quiescence were calculated using the statistics Z and ß and for Time Window lengths between 1 and 5 years. Five positive anomalies were found, which can be associated with large earthquakes (MS≥7.2).Finally, a Monte Carlo approach was utilized to evaluate the ground motion hazard and its uncertainties in northern Central America. A set of new seismic hazard maps exhibiting probabilistic values of peak ground acceleration (PGA) with 50%, 10%, and 5% probabilities of exceedance (PE) in 50 years is presented for a large area of northern Central America, including El Salvador and Guatemala.
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