Science.gov

Sample records for present-day mexican-mestizos revealed

  1. The rs3857059 variant of the SNCA gene is associated with Parkinson's disease in Mexican Mestizos.

    PubMed

    García, S; Chavira-Hernández, G; Gallegos-Arreola, M P; Dávila-Maldonado, L; García Martínez, F; Montes Almanza, L A; Palma-Flores, C; Mondragón-Terán, P; Alcaraz Estrada, S L; López-Hernández, L B

    2016-06-01

    Among the candidate genes for Parkinson's disease (PD), SNCA has replicated association in different populations. Besides other known mutations in the SNCA gene, the rs3857059 variant has also been linked to various neurodegenerative disorders. Therefore, the aim of the present study was to search for association of this variant and sporadic PD in Mexican Mestizo patients. A case-control study was performed including 241 individuals, 106 patients, and 135 healthy controls. Genotyping was performed using real-time PCR. The rs3857059 variant demonstrated an association with PD in Mexican Mestizos (OR = 2.40, CI, 1.1 to 5.1, p = 0.02) under the recessive model. In addition, a gender effect was found for the GG genotype in females (OR = 1.31, CI, 1.01 to 1.7, p = 0.037). This is the first study to confirm an association of the rs3857059 variant with PD and also to show a gender effect. Our data contribute to the elucidation of the link between rs3857059 and susceptibility to PD observed in the Mexican Mestizo population. PMID:27332068

  2. Molecular study of VWF gene from Mexican Mestizo patients with von Willebrand disease, and the finding of three new mutations.

    PubMed

    Melo-Nava, Brenda M; Benítez, Herminia; Palacios, J Jorge; Nieva, Beatriz; Arenas, Diego; Jaloma-Cruz, A Rebeca; Navarrete, Carmen; Salamanca, Fabio; Peñaloza, Rosenda

    2007-01-01

    To investigate the origin of von Willebrand disease in Mexican Mestizo population, we analyzed exons 18, 19, 20, 28, 45, and 52 of the VWF gene from 34 Mexican Mestizo index cases, 28 of them affected but not related, using DNA amplification by polymerase chain reaction and direct sequencing. We found three novel mutations: E1447Q in one patient with type 1; P2781S in one patient with type 2M; and P812L in another type 1/2N patient. These mutations were not found in 100 normal alleles. Moreover, we found other mutations previously reported in the literature; one of them (G1609R) was the most frequent (6/28) in patients with VWD type 2A. This is the first molecular study in a Mexican group that has a particular mixture of Indigenous, Caucasian, and African genes. PMID:17681836

  3. Mitogenomes from The 1000 Genome Project Reveal New Near Eastern Features in Present-Day Tuscans

    PubMed Central

    Pardo-Seco, Jacobo; Amigo, Jorge; Martinón-Torres, Federico

    2015-01-01

    Background Genetic analyses have recently been carried out on present-day Tuscans (Central Italy) in order to investigate their presumable recent Near East ancestry in connection with the long-standing debate on the origins of the Etruscan civilization. We retrieved mitogenomes and genome-wide SNP data from 110 Tuscans analyzed within the context of The 1000 Genome Project. For phylogeographic and evolutionary analysis we made use of a large worldwide database of entire mitogenomes (>26,000) and partial control region sequences (>180,000). Results Different analyses reveal the presence of typical Near East haplotypes in Tuscans representing isolated members of various mtDNA phylogenetic branches. As a whole, the Near East component in Tuscan mitogenomes can be estimated at about 8%; a proportion that is comparable to previous estimates but significantly lower than admixture estimates obtained from autosomal SNP data (21%). Phylogeographic and evolutionary inter-population comparisons indicate that the main signal of Near Eastern Tuscan mitogenomes comes from Iran. Conclusions Mitogenomes of recent Near East origin in present-day Tuscans do not show local or regional variation. This points to a demographic scenario that is compatible with a recent arrival of Near Easterners to this region in Italy with no founder events or bottlenecks. PMID:25786119

  4. Admixture and genetic relationships of Mexican Mestizos regarding Latin American and Caribbean populations based on 13 CODIS-STRs.

    PubMed

    Salazar-Flores, J; Zuñiga-Chiquette, F; Rubi-Castellanos, R; Álvarez-Miranda, J L; Zetina-Hérnandez, A; Martínez-Sevilla, V M; González-Andrade, F; Corach, D; Vullo, C; Álvarez, J C; Lorente, J A; Sánchez-Diz, P; Herrera, R J; Cerda-Flores, R M; Muñoz-Valle, J F; Rangel-Villalobos, H

    2015-02-01

    Short tandem repeats (STRs) of the combined DNA index system (CODIS) are probably the most employed markers for human identification purposes. STR databases generated to interpret DNA profiles are also helpful for anthropological purposes. In this work, we report admixture, population structure, and genetic relationships of Mexican Mestizos with respect to Latin American and Caribbean populations based on 13 CODIS-STRs. In addition, new STR population data were included from Tijuana, Baja California (Northwest, Mexico), which represents an interesting case of elevated genetic flow as a bordering city with the USA. Inter-population analyses included CODIS-STR data from 11 Mexican Mestizo, 12 Latin American and four Caribbean populations, in addition to European, Amerindian, and African genetic pools as ancestral references. We report allele frequencies and statistical parameters of forensic interest (PD, PE, Het, PIC, typical PI), for 15 STRs in Tijuana, Baja California. This Mexican border city was peculiar by the increase of African ancestry, and by presenting three STRs in Hardy-Weinberg disequilibrium, probably explained by recurrent gene flow. The Amerindian ancestry in Central and Southeast of Mexico was the greatest in Latin America (50.9-68.6%), only comparable with the North of Central America and Ecuador (48.8-56.4%), whereas the European ancestry was prevalent in South America (66.7-75%). The African ancestry in Mexico was the smallest (2.2-6.3%) in Latin America (≥ 2.6%), particularly regarding Brazil (21%), Honduras (62%), and the Caribbean (43.2-65.2%). CODIS-STRs allowed detecting significant population structure in Latin America based on greater presence of European, Amerindian, and African ancestries in Central/South America, Mexican Mestizos, and the Caribbean, respectively. PMID:25435058

  5. Calpain-10 gene polymorphisms and risk of type 2 diabetes mellitus in Mexican mestizos.

    PubMed

    Picos-Cárdenas, V J; Sáinz-González, E; Miliar-García, A; Romero-Zazueta, A; Quintero-Osuna, R; Leal-Ugarte, E; Peralta-Leal, V; Meza-Espinoza, J P

    2015-01-01

    The calpain-10 gene is expressed primarily in tissues important in glucose metabolism; thus, some of its polymorphisms have been associated with type 2 diabetes. In this study, we examined the association between the calpain-10 single-nucleotide polymorphism (SNP)-43, SNP-19, and SNP-63 and type 2 diabetes in Mexican mestizos. We included 211 patients and 152 non-diabetic subjects. Polymerase chain reaction was used to identify alleles. We compared allele, genotype, haplotype, and diplotype frequencies between both groups and used the chi-square test to calculate the risk. The allele frequency of SNP-43 allele 1 was 70% in controls and 72% in patients; the GG, GA, and AA genotype frequencies were 48.7, 42.8, and 8.5% in controls and 51.2, 41.7, and 7.1% in patients, respectively. For SNP- 19, the prevalence of allele 1 (2R) was 32% in controls and 39% in patients. In controls, homozygosity (2R/2R) was 10.5%, heterozygosity was 42.8%, and 3R/3R was 46.7%; in cases, these values were 13.3, 50.7, and 36.0%, respectively. For SNP-63, the frequency of allele 1 was 87% in controls and 83% in patients; genotype frequencies in controls were 75.7% (CC), 23% (CT), and 1.3% (TT), and were 69.7, 27.5, and 2.8%, respectively for the cases. Genotype distributions were consistent with Hardy-Weinberg equilibrium. No significant intergroup differences for allele, genotype, haplotype, or diplotype frequencies were observed. We found no association between these polymorphisms and diabetes. However, our sample size was small, so the role of calpain-10 risk alleles should be further examined. PMID:25867367

  6. Contribution of Common Genetic Variation to the Risk of Type 2 Diabetes in the Mexican Mestizo Population

    PubMed Central

    Gamboa-Meléndez, Marco Alberto; Huerta-Chagoya, Alicia; Moreno-Macías, Hortensia; Vázquez-Cárdenas, Paola; Ordóñez-Sánchez, María Luisa; Rodríguez-Guillén, Rosario; Riba, Laura; Rodríguez-Torres, Maribel; Guerra-García, María Teresa; Guillén-Pineda, Luz Elizabeth; Choudhry, Shweta; del Bosque-Plata, Laura; Canizales-Quinteros, Samuel; Pérez-Ortiz, Gustavo; Escobedo-Aguirre, Fernando; Parra, Adalberto; Lerman-Garber, Israel; Aguilar-Salinas, Carlos Alberto; Tusié-Luna, María Teresa

    2012-01-01

    Several studies have identified nearly 40 different type 2 diabetes susceptibility loci, mainly in European populations, but few of them have been evaluated in the Mexican population. The aim of this study was to examine the extent to which 24 common genetic variants previously associated with type 2 diabetes are associated in Mexican Mestizos. Twenty-four single nucleotide polymorphisms (SNPs) in or near genes (KCNJ11, PPARG, TCF7L2, SLC30A8, HHEX, CDKN2A/2B, CDKAL1, IGF2BP2, ARHGEF11, JAZF1, CDC123/CAMK1D, FTO, TSPAN8/LGR5, KCNQ1, THADA, ADAMTS9, NOTCH2, NXPH1, RORA, UBQLNL, and RALGPS2) were genotyped in Mexican Mestizos. A case-control association study comprising 1,027 type 2 diabetic individuals and 990 control individuals was conducted. To account for population stratification, a panel of 104 ancestry-informative markers was analyzed. Association to type 2 diabetes was found for rs13266634 (SLC30A8), rs7923837 (HHEX), rs10811661 (CDKN2A/2B), rs4402960 (IGF2BP2), rs12779790 (CDC123/CAMK1D), and rs2237892 (KCNQ1). In addition, rs7754840 (CDKAL1) was associated in the nonobese type 2 diabetic subgroup, and for rs7903146 (TCF7L2), association was observed for early-onset type 2 diabetes. Lack of association for the rest of the variants may have resulted from insufficient power to detect smaller allele effects. PMID:22923468

  7. Ancient DNA reveals matrilineal continuity in present-day Poland over the last two millennia.

    PubMed

    Juras, Anna; Dabert, Miroslawa; Kushniarevich, Alena; Malmström, Helena; Raghavan, Maanasa; Kosicki, Jakub Z; Metspalu, Ene; Willerslev, Eske; Piontek, Janusz

    2014-01-01

    While numerous ancient human DNA datasets from across Europe have been published till date, modern-day Poland in particular, remains uninvestigated. Besides application in the reconstruction of continent-wide human history, data from this region would also contribute towards our understanding of the history of the Slavs, whose origin is hypothesized to be in East or Central Europe. Here, we present the first population-scale ancient human DNA study from the region of modern-day Poland by establishing mitochondrial DNA profiles for 23 samples dated to 200 BC - 500 AD (Roman Iron Age) and for 20 samples dated to 1000-1400 AD (Medieval Age). Our results show that mitochondrial DNA sequences from both periods belong to haplogroups that are characteristic of contemporary West Eurasia. Haplotype sharing analysis indicates that majority of the ancient haplotypes are widespread in some modern Europeans, including Poles. Notably, the Roman Iron Age samples share more rare haplotypes with Central and Northeast Europeans, whereas the Medieval Age samples share more rare haplotypes with East-Central and South-East Europeans, primarily Slavic populations. Our data demonstrates genetic continuity of certain matrilineages (H5a1 and N1a1a2) in the area of present-day Poland from at least the Roman Iron Age until present. As such, the maternal gene pool of present-day Poles, Czechs and Slovaks, categorized as Western Slavs, is likely to have descended from inhabitants of East-Central Europe during the Roman Iron Age. PMID:25337992

  8. Ancient DNA Reveals Matrilineal Continuity in Present-Day Poland over the Last Two Millennia

    PubMed Central

    Juras, Anna; Dabert, Miroslawa; Kushniarevich, Alena; Malmström, Helena; Raghavan, Maanasa; Kosicki, Jakub Z.; Metspalu, Ene; Willerslev, Eske; Piontek, Janusz

    2014-01-01

    While numerous ancient human DNA datasets from across Europe have been published till date, modern-day Poland in particular, remains uninvestigated. Besides application in the reconstruction of continent-wide human history, data from this region would also contribute towards our understanding of the history of the Slavs, whose origin is hypothesized to be in East or Central Europe. Here, we present the first population-scale ancient human DNA study from the region of modern-day Poland by establishing mitochondrial DNA profiles for 23 samples dated to 200 BC – 500 AD (Roman Iron Age) and for 20 samples dated to 1000–1400 AD (Medieval Age). Our results show that mitochondrial DNA sequences from both periods belong to haplogroups that are characteristic of contemporary West Eurasia. Haplotype sharing analysis indicates that majority of the ancient haplotypes are widespread in some modern Europeans, including Poles. Notably, the Roman Iron Age samples share more rare haplotypes with Central and Northeast Europeans, whereas the Medieval Age samples share more rare haplotypes with East-Central and South-East Europeans, primarily Slavic populations. Our data demonstrates genetic continuity of certain matrilineages (H5a1 and N1a1a2) in the area of present-day Poland from at least the Roman Iron Age until present. As such, the maternal gene pool of present-day Poles, Czechs and Slovaks, categorized as Western Slavs, is likely to have descended from inhabitants of East-Central Europe during the Roman Iron Age. PMID:25337992

  9. High resolution human leukocyte antigen (HLA) class I and class II allele typing in Mexican mestizo women with sporadic breast cancer: case-control study

    PubMed Central

    2009-01-01

    Background The development of breast cancer is multifactorial. Hormonal, environmental factors and genetic predisposition, among others, could interact in the presentation of breast carcinoma. Human leukocyte antigen (HLA) alleles play an important role in immunity (cellular immunity) and may be important genetic traits. HLAAllele-specific interaction has not been well established. Recently, several studies had been conducted in order to do so, but the results are controversial and in some instances contradictory. Methods We designed a case-control study to quantify the association of HLA class I and II genes and breast cancer. HLA typing was performed by high resolution sequence-specific oligotyping after DNA amplification (PCR-SSOP) of 100 breast cancer Mexican mestizo patients and 99 matched healthy controls. Results HLA-A frequencies that we were able to observe that there was no difference between both groups from the statistical viewpoint. HLA-B*1501 was found three times more common in the case group (OR, 3.714; p = 0.031). HLA-Cw is not a marker neither for risk, nor protection for the disease, because we did not find significant statistical differences between the two groups. DRB1*1301, which is expressed in seven cases and in only one control, observing an risk increase of up to seven times and DRB1*1602, which behaves similarly in being present solely in the cases (OR, 16.701; 95% CI, 0.947 – 294.670). DQ*0301-allele expression, which is much more common in the control group and could be protective for the presentation of the disease (OR, 0.078; 95% CI, 0.027–0.223, p = 0.00001). Conclusion Our results reveal the role of the MHC genes in the pathophysiology of breast cancer, suggesting that in the development of breast cancer exists a disorder of immune regulation. The triggering factor seems to be restricted to certain ethnic groups and certain geographical regions since the relevant MHC alleles are highly diverse. This is the first study in Mexican

  10. Genetic Variants in IL6R and ADAM19 are Associated with COPD Severity in a Mexican Mestizo Population.

    PubMed

    Pérez-Rubio, Gloria; Silva-Zolezzi, Irma; Fernández-López, Juan Carlos; Camarena, Ángel; Velázquez-Uncal, Mónica; Morales-Mandujano, Fabiola; Hernández-Zenteno, Rafael De Jesús; Flores-Trujillo, Fernando; Sánchez-Romero, Candelaria; Velázquez-Montero, Alejandra; Espinosa de Los Monteros, Carlos; Sansores, Raúl H; Ramírez-Venegas, Alejandra; Falfán-Valencia, Ramcés

    2016-10-01

    Chronic obstructive pulmonary disease (COPD) is a complex and multifactorial disease with a strong genetic component. Our objective is to identify the genetic variants associated with COPD risk and its severity in Mexican Mestizo population. We evaluated 1285 single-nucleotide polymorphisms (SNPs) of candidate genes in 299 smokers with COPD (COPD-S) and 531 smokers without COPD (SWOC) using an Illumina GoldenGate genotyping microarray. In addition, 251 ancestry informative markers were included. Allele A of rs2545771 in CYP2F2P is associated with a lower risk of COPD (p = 4.02E-10, odds ratio [OR] = 0.104, confidence interval [CI] 95% 0.05-0.18). When the COPD group was stratified by severity according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD; levels III + IV vs. I + II), 3 SNPs (rs4329505 and rs4845626 in interleukin 6 receptor [IL6R] and rs1422794 in a disintegrin and metalloproteinase domain 19 [ADAM19]) were associated with a lower risk of suffering the most severe stages of the disease. rs2819096 in the surfactant protein D (SFTPD) gene was associated with a higher risk of COPD GOLD III + IV (p = 7.79E-03, OR = 1.80, CI 95% 1.16-2.79). Finally, the haplotype in IL6R was associated with a lower risk of suffering from more severe COPD, whereas the haplotype in ADAM19 was associated with a higher risk (p = 7.40E-03, OR = 2.83, CI 95% 1.20-6.86) of suffering from the severe stages of the disease. Our data suggest that there are alleles and haplotypes in the IL6R, ADAM19, and SFTPD genes associated with different severity stages of COPD; in CYP2F2P, rs25455771 is associated with a lower risk of COPD. PMID:27078193

  11. Analysis of Polymorphisms in Interleukin-10, Interleukin-6, and Interleukin-1 Receptor Antagonist in Mexican-Mestizo Women with Pre-eclampsia

    PubMed Central

    Valencia Villalvazo, Elith Yazmin; Canto-Cetina, Thelma; Romero Arauz, Juan Fernando; Coral-Vázquez, Ramón Mauricio; Canizales-Quinteros, Samuel; Coronel, Agustín; Carlos Falcón, Juan; Hernández Rivera, Jaime; Ibarra, Roberto; Polanco Reyes, Lucila

    2012-01-01

    Due to the fact that studies seeking associations of polymorphisms in regulatory regions of cytokine genes with pre-eclampsia (PE) have not always been consistent in different population analyses, the aim of this study was to investigate the possible association between rs1800896 of interleukin-10 (IL-10), rs1800795 of interleukin-6 (IL-6), and the variable number of tandem repeats (VNTR) in intron 2 of interleukin-1 receptor antagonist (IL-1Ra), as well as gene–gene interactions between these three polymorphisms with the presence of PE in Mexican-Mestizo women and one Amerindian population from México (Maya). A case–control study was performed where 411 pre-eclamptic cases and 613 controls were genotyped. For the rs1800896 of IL-10 and rs1800795 of IL-6, we used real-time polymerase chain reaction (PCR) allelic discrimination and for the VNTR of IL-1Ra, PCR. Allele frequency differences were assessed by Chi-squared test; logistic regression was used to test for associations; a gene–gene interaction was conducted. Genotypic and allelic distribution of the polymorphisms was similar in our population. The estimated of the gene–gene interaction between the polymorphisms did not differ significantly. However, we observed important differences in the distribution of the alleles and genotypes of the three polymorphisms analyzed between Mestiza-Mexicanas and Maya-Mestizo women. In conclusion, we did not find an association between polymorphisms in IL-10, IL-6, and IL-1Ra and PE in Mexican-Mestizo and Maya-Mestizo women. To our knowledge, this is the first time that these three polymorphisms were analyzed together with gene–gene interaction in women with PE. PMID:23013217

  12. Present-day deformation of the Pyrenees revealed by GPS surveying and earthquake focal mechanisms until 2011

    NASA Astrophysics Data System (ADS)

    Rigo, A.; Vernant, P.; Feigl, K. L.; Goula, X.; Khazaradze, G.; Talaya, J.; Morel, L.; Nicolas, J.; Baize, S.; Chéry, J.; Sylvander, M.

    2015-05-01

    The Pyrenean mountain range is a slowly deforming belt with continuous and moderate seismic activity. To quantify its deformation field, we present the velocity field estimated from a GPS survey of the Pyrenees spanning 18 yr. The PotSis and ResPyr networks, including a total of 85 GPS sites, were installed and first measured in 1992 and 1995-1997, respectively, and remeasured in 2008 and 2010. We obtain a deformation field with velocities less than 1 mm yr-1 across the range. The estimated velocities for individual stations do not differ significantly from zero with 95 per cent confidence. Even so, we estimate a maximum extensional horizontal strain rate of 2.0 ± 1.7 nanostrain per year in a N-S direction in the western part of the range. We do not interpret the vertical displacements due to their large uncertainties. In order to compare the horizontal strain rates with the seismic activity, we analyse a set of 194 focal mechanisms using three methods: (i) the `r' factor relating their P and T axes, (ii) the stress tensors obtained by fault slip inversion and (iii) the strain-rate tensors. Stress and strain-rate tensors are estimated for: (i) the whole data set, (ii) the eastern and western parts of the range separately, and (iii) eight zones, which are defined based on the seismicity and the tectonic patterns of the Pyrenees. Each of these analyses reveals a lateral variation of the deformation style from compression and extension in the east to extension and strike-slip in the west of the range. Although the horizontal components of the strain-rate tensors estimated from the seismic data are slightly smaller in magnitude than those computed from the GPS velocity field, they are consistent within the 2σ uncertainties. Furthermore, the orientations of their principal axes agree with the mapped active faults.

  13. Expression of NAT2 in immune system cells and the relation of NAT2 gene polymorphisms in the anti-tuberculosis therapy in Mexican mestizo population.

    PubMed

    Salazar-González, R; Gómez, R; Romano-Moreno, S; Medellín-Garibay, S; Núñez-Ruíz, A; Magaña-Aquino, M; Milán-Segovia, R C; Portales-Pérez, D P

    2014-12-01

    Arylamine N-acetyltransferase 2 (NAT2) metabolizes isoniazid (INH) and Single Nucleotide Polymorphisms (SNP) responsible for its activity has been reported. The aim of this study in the Mexican mestizo population was to evaluate NAT2 expression at the protein level in immune cells, as well as the distribution and frequency of six NAT2 SNPs and their association with anti-TB therapy, by measuring the plasma levels of INH and Acetyl-INH (AcINH). We performed genotyping assays of NAT2 SNPs in 40 TB patients and 121 healthy volunteers by real-time PCR. A method for detecting NAT2 in immune cells using flow cytometry was developed. Plasma concentrations of INH and AcINH were obtained by HPLC in TB patients and the Metabolic Ratio (MR) was calculated. The phenotypes obtained in the healthy volunteers were as follows; 18.87 % of subjects had the rapid acetylator phenotype, 45.45 % had the intermediate phenotype and 39.66 % exhibited the slow acetylator phenotype. In the TB patient group, 35 % of patients had the rapid acetylator phenotype, 32.5 % were intermediate and 32.5 % showed the slow acetylator phenotype. A higher expression level of NAT2 in innate immune cells from TB patients compared to those from healthy volunteers was detected (P < 0.013). In TB patients the MR showed a bimodal distribution with an antimode of 0.7, which was used as a threshold value for acetylator classification. A high correspondence between the rapid and slow acetylator phenotype with MR was demonstrated. In conclusion, the 282C>T, 341T>C, 481C>T, 590G>A, 803A>G, 857G>A SNPs of NAT2 gene provides accurate for prediction of the acetylator phenotype in Mexican mestizo population. A statistical difference was found in frequency of rapid metabolizer phenotype, which was higher in TB patients. In addition, the expression of NAT2 protein in immune cells can lead to further studies related to its functional role in the innate immune response against M. tuberculosis and other xenobiotics

  14. CYP2C9, CYP2C19, ABCB1 genetic polymorphisms and phenytoin plasma concentrations in Mexican-Mestizo patients with epilepsy.

    PubMed

    Ortega-Vázquez, A; Dorado, P; Fricke-Galindo, I; Jung-Cook, H; Monroy-Jaramillo, N; Martínez-Juárez, I E; Familiar-López, I; Peñas-Lledó, E; LLerena, A; López-López, M

    2016-06-01

    We aimed to explore the possible influence of CYP2C9 (*2, *3 and IVS8-109 A>T), CYP2C19 (*2, *3 and *17) and ABCB1 (1236C>T, 2677G>A/T and 3435C>T) on phenytoin (PHT) plasma concentrations in 64 Mexican Mestizo (MM) patients with epilepsy currently treated with PHT in mono- (n=25) and polytherapy (n=39). Genotype and allele frequencies of these variants were also estimated in 300 MM healthy volunteers. Linear regression models were used to assess associations between the dependent variables (PHT plasma concentration and dose-corrected PHT concentration) with independent variables (CYP2C9, CYP2C19 and ABCB1 genotypes, ABCB1 haplotypes, age, sex, weight, and polytherapy). In multivariate models, CYP2C9 IVS8-109 T was significantly associated with higher PHT plasma concentrations (t(64)=2.27; P=0.03). Moreover, this allele was more frequent in the supratherapeutic group as compared with the subtherapeutic group (0.13 versus 0.03, respectively; P=0.05, Fisher's exact test). Results suggest that CYP2C9 IVS8-109 T allele may decrease CYP2C9 enzymatic activity on PHT. More research is needed to confirm findings. PMID:26122019

  15. The 482Ser of PPARGC1A and 12Pro of PPARG2 Alleles Are Associated with Reduction of Metabolic Risk Factors Even Obesity in a Mexican-Mestizo Population

    PubMed Central

    Vázquez-Del Mercado, Mónica; Guzmán-Ornelas, Milton-Omar; Corona Meraz, Fernanda-Isadora; Ríos-Ibarra, Clara-Patricia; Reyes-Serratos, Eduardo-Alejandro; Castro-Albarran, Jorge; Ruíz-Quezada, Sandra-Luz; Navarro-Hernández, Rosa-Elena

    2015-01-01

    The aim of this study was to investigate the relationship between functional polymorphisms Gly482Ser in PPARGC1A and Pro12Ala in PPARG2 with the presence of obesity and metabolic risk factors. We included 375 individuals characterized as Mexican-Mestizos and classified by the body mass index (BMI). Body dimensions and distribution of body fat were measured. The HOMA-IR and adiposity indexes were calculated. Adipokines and metabolic profile quantification were performed by ELISA and routine methods. Genetic polymorphisms were determined by polymerase chain reaction restriction fragment length polymorphism analysis. A difference between obese and nonobese subjects in polymorphism PPARGC1A distribution was observed. Among obese individuals, carriers of genotype 482Gly/Gly were observed to have decreased body fat, BMI, and body fat ratio versus 482Ser/Ser carriers and increased resistin and leptin levels in carriers Gly+ phenotype versus Gly− phenotype. Subjects with PPARG2 Ala− phenotype (genotype 12Pro/Pro) showed a decreased HOMA-IR index versus individuals with Ala+ phenotype (genotypes 12Pro/Ala plus 12Ala/Ala). We propose that, in obese Mexican-Mestizos, the combination of alleles 482Ser in PPARGC1A and 12Pro in PPARG2 represents a reduced metabolic risk profile, even when the adiposity indexes are increased. PMID:26185753

  16. TGFBR2 mutation and MTHFR-C677T polymorphism in a Mexican mestizo population with cervico-cerebral artery dissection.

    PubMed

    Ruiz-Franco, Angélica; Barboza, Miguel A; Jara-Prado, Aurelio; Canizales-Quinteros, Samuel; Leon-Mimila, Paola; Arguelles-Morales, Nayelli; Vargas-González, Juan-Camilo; Quiroz-Compean, Alejandro; Arauz, Antonio

    2016-06-01

    Spontaneous cervico-cerebral artery dissection (CCAD) is a common condition found among young patients with ischemic stroke. We examined the possible association between the polymorphism of methylenetetrahydrofolate reductase (MTHFR)-C677T and the gene mutation in transforming growth factor beta receptor II (TGFBR2) in a cohort of CCAD patients. One-hundred CCAD cases (65 males; mean age: 38.08 ± 10.68 years) and 100 matching controls were included. Ancestry informative markers (AIMs) were used to increase internal validity of the genetic analysis. Genotypes of the C677T polymorphism in the MTHFR gene were determined by polymerase chain reaction and restriction fragment length polymorphism; direct sequencing was used for a mutation analysis of the TGFBR2 gene. Associations were evaluated using a multivariate statistics, and Hardy-Weinberg equilibrium was analyzed. We also incorporated our data into a meta-analysis of the MTHFR-C677T. Sixty-three patients presented with vertebral and 37 with carotid artery dissection. Ancestry markers found a call rate on each over 95 %. All AIMs did not deviate from Hardy-Weinberg equilibrium (p > 0.05). The homozygous TT genotype was more frequent in cases (OR 2.04, CI 95 % 1.53-2.72, p = 0.005), whereas no significant difference was found on heterozygous CT genotype. TGFBR2 mutation was not present in our samples. In the meta-analysis of MTHFR/C677T variant, a total 613 cases and 1547 controls were analyzed; we found a moderate association for the recessive model genotype (OR 2.04, CI 95 % 1.53-2.72; p = 0.342; Z = 4.83; I (2) = 11.3). This study supports a positive association between the MTHFR-C677T polymorphism and genetically confirmed Mexican mestizo CCAD patients. PMID:27017342

  17. The Italian present-day stress map

    NASA Astrophysics Data System (ADS)

    Montone, Paola; Mariucci, Maria Teresa; Pierdominici, Simona

    2012-05-01

    In this paper, we present a significant update of the Italian present-day stress data compilation not only to improve the knowledge on the tectonic setting of the region or to constrain future geodynamic models, but also to understand the mechanics of processes linked to faulting and earthquakes. In this paper, we have analysed, revised and collected new contemporary stress data from borehole breakouts and we have assembled earthquake and fault data. In total, 206 new quality-ranked entries complete the definition of the horizontal stress orientation and tectonic regime in some areas, and bring new information mainly in Sicily and along the Apenninic belt. Now the global Italian data set consists of 715 data points, including 499 of A-C quality, representing an increase of 37 per cent compared to the previous compilation. The alignment of horizontal stresses measured in some regions, closely matches the ˜N-S first-order stress field orientation of ongoing relative crustal motions between Eurasia and Africa plates. The Apenninic belt shows a diffuse extensional stress regime indicating a ˜NE-SW direction of extension, that we interpret as related to a second-order stress field. The horizontal stress rotations observed in peculiar areas reflect a complex interaction between first-order stress field and local effects revealing the importance of the tectonic structure orientations. In particular, in Sicily the new data delineate a more complete tectonic picture evidencing adjacent areas characterized by distinct stress regime: northern offshore of Sicily and in the Hyblean plateau the alignment of horizontal stresses is consistent with the crustal motions, whereas different directions have been observed along the belt and foredeep.

  18. The landscape of Neandertal ancestry in present-day humans

    PubMed Central

    Sankararaman, Sriram; Mallick, Swapan; Dannemann, Michael; Prüfer, Kay; Kelso, Janet; Pääbo, Svante; Patterson, Nick; Reich, David

    2014-01-01

    Analyses of Neandertal genomes have revealed that Neandertals have contributed genetic variants to modern humans1–2. The antiquity of Neandertal gene flow into modern humans means that regions that derive from Neandertals in any one human today are usually less than a hundred kilobases in size. However, Neandertal haplotypes are also distinctive enough that several studies have been able to detect Neandertal ancestry at specific loci1,3–8. Here, we have systematically inferred Neandertal haplotypes in the genomes of 1,004 present-day humans12. Regions that harbor a high frequency of Neandertal alleles in modern humans are enriched for genes affecting keratin filaments suggesting that Neandertal alleles may have helped modern humans adapt to non-African environments. Neandertal alleles also continue to shape human biology, as we identify multiple Neandertal-derived alleles that confer risk for disease. We also identify regions of millions of base pairs that are nearly devoid of Neandertal ancestry and enriched in genes, implying selection to remove genetic material derived from Neandertals. Neandertal ancestry is significantly reduced in genes specifically expressed in testis, and there is an approximately 5-fold reduction of Neandertal ancestry on chromosome X, which is known to harbor a disproportionate fraction of male hybrid sterility genes20–22. These results suggest that part of the reduction in Neandertal ancestry near genes is due to Neandertal alleles that reduced fertility in males when moved to a modern human genetic background. PMID:24476815

  19. Common Characteristics of Models in Present-Day Scientific Practice

    ERIC Educational Resources Information Center

    Van Der Valk, Ton; Van Driel, Jan H.; De Vos, Wobbe

    2007-01-01

    Teaching the use of models in scientific research requires a description, in general terms, of how scientists actually use models in their research activities. This paper aims to arrive at defining common characteristics of models that are used in present-day scientific research. Initially, a list of common features of models and modelling, based…

  20. The present-day number of tectonic plates

    NASA Astrophysics Data System (ADS)

    Harrison, Christopher G. A.

    2016-03-01

    The number of tectonic plates on Earth described in the literature has expanded greatly since the start of the plate tectonic era, when only about a dozen plates were considered in global models of present-day plate motions. With new techniques of more accurate earthquake epicenter locations, modern ways of measuring ocean bathymetry using swath mapping, and the use of space based geodetic techniques, there has been a huge growth in the number of plates thought to exist. The study by Bird (2003) proposed 52 plates, many of which were delineated on the basis of earthquake locations. Because of the pattern of areas of these plates, he suggested that there should be more small plates than he could identify. In this paper, I gather together publications that have proposed a total of 107 new plates, giving 159 plates in all. The largest plate (Pacific) is about 20 % of the Earth's area or 104 Mm2, and the smallest of which (Plate number 5 from Hammond et al. 2011) is only 273 km2 in area. Sorting the plates by size allows us to investigate how size varies as a function of order. There are several changes of slope in the plots of plate number organized by size against plate size order which are discussed. The sizes of the largest seven plates is constrained by the area of the Earth. A middle set of 73 plates down to an area of 97,563 km2 (the Danakil plate at number 80, is the plate of median size) follows a fairly regular pattern of plate size as a function of plate number. For smaller plates, there is a break in the slope of the plate size/plate number plot and the next 32 plates follow a pattern of plate size proposed by the models of Koehn et al. (2008) down to an area of 11,638 km2 (West Mojave plate # 112). Smaller plates do not follow any regular pattern of area as a function of plate number, probably because we have not sampled enough of these very small plates to reveal any clear pattern.

  1. Nuclear Fusion Drives Present-Day Accelerated Cosmic Expansion

    SciTech Connect

    Ying, Leong

    2010-09-30

    The widely accepted model of our cosmos is that it began from a Big Bang event some 13.7 billion years ago from a single point source. From a twin universe perspective, the standard stellar model of nuclear fusion can account for the Dark Energy needed to explain the mechanism for our present-day accelerated expansion. The same theories can also be used to account for the rapid inflationary expansion at the earliest time of creation, and predict the future cosmic expansion rate.

  2. Overcoming Present-Day Powerplant Limitations Via Unconventional Engine Configurations

    NASA Technical Reports Server (NTRS)

    Meitner, Peter L.

    2006-01-01

    The Army Research Laboratory s Vehicle Technology Directorate is sponsoring the prototype development of three unconventional engine concepts - two intermittent combustion (IC) engines and one turbine engine (via SBIR (Small Business Innovative Research) contracts). The IC concepts are the Nutating Engine and the Bonner Engine, and the turbine concept is the POWER Engine. Each of the three engines offers unique and greatly improved capabilities (which cannot be achieved by present-day powerplants), while offering significant reductions in size and weight. This paper presents brief descriptions of the physical characteristics of the three engines, and discusses their performance potentials, as well as their development status.

  3. Present-day dynamic and residual topography in central Anatolia

    NASA Astrophysics Data System (ADS)

    Uluocak, Ebru Şengül; Pysklywec, Russell; Göğüş, Oğuz H.

    2016-06-01

    The Central Anatolian orogenic plateau is represented by young volcanism, rapid plateau uplift, and distinctive (past and active) tectonic deformation. In this study, we consider observational data in terms of regional present-day geodynamics in the region. The residual topography of Central Anatolia was derived to define the regional isostatic conditions according to Airy isostasy and infer the potential role of "dynamic topography". Two-dimensional thermo-mechanical forward models for coupled mantle-lithosphere flow/deformation were conducted along a N-S directional profile through the region (e.g. northern/Pontides, interior, and southern/Taurides). These models were based on seismic tomography data that provide estimates about the present-day mantle thermal structure beneath the Anatolian plate. We compare the modelling results with calculated residual topography and independent data sets of geological deformation, gravity, and high surface heat flow/widespread geothermal activity. Model results suggest that there is ˜1 km of mantle flow induced dynamic topography associated with the sub-lithospheric flow driven by the seismically-inferred mantle structure. The uprising mantle may have also driven the asthenospheric source of volcanism in the north (e.g. Galatia volcanic province) and the Cappadocia volcanic province in the south while elevating the surface in the last 10 Myrs. Our dynamic topography calculations emphasize the role of vertical forcing under other orogenic plateaux underlain by relatively thin crust and low-density asthenospheric mantle.

  4. Present-day Antarctic Ice Mass Changes and Crustal Motion

    NASA Technical Reports Server (NTRS)

    James, Thomas S.; Ivins, Erik R.

    1995-01-01

    The peak vertical velocities predicted by three realistic, but contrasting, present-day scenarios of Antarctic ice sheet mass balance are found to be of the order of several mm/a. One scenario predicts local uplift rates in excess of 5 mm/a. These rates are small compared to the peak Antarctic vertical velocities of the ICE-3G glacial rebound model, which are in excess of 20 mm/a. If the Holocene Antarctic deglaciation history portrayed in ICE-3G is realistic, and if regional upper mantle viscosity is not an order of magnitude below 10(exp 21) pa s, then a vast geographical region in West Antarctica is uplifting at a rate that could be detected by a future Global Positioning System (GPS) campaign. While present-day scenarios predict small vertical crustal velocities, their overall continent-ocean mass exchange is large enough to account for a substantial portion of the observed secular polar motion ((Omega)m(bar)) and time-varying zonal gravity field J(sub 1).

  5. Present-day Antarctic ice mass changes and crustal motion

    NASA Technical Reports Server (NTRS)

    James, Thomas S.; Ivins, Erik R.

    1995-01-01

    The peak vertical velocities predicted by three realistic, but contrasting, present-day scenarios of Antarctic ice sheet mass balance are found to be of the order of several mm/a. One scenario predicts local uplift rates in excess of 5 mm/a. These rates are small compared to the peak Antarctic vertical velocities of the ICE-3G glacial rebound model, which are in excess of 20 mm/a. If the Holocene Antarctic deglaciation history protrayed in ICE-3G is realistic, and if regional upper mantle viscosity is not an order of magnitude below 10(exp 21) Pa(dot)s, then a vast geographical region in West Antarctica is uplifting at a rate that could be detected by a future Global Positioning System (GPS) campaign. While present-day scenarios predict small vertical crustal velocities, their overall continent-ocean mass exchange is large enough to account for a substantial portion of the observed secular polar motion (omega m(arrow dot)) and time-varying zonal gravity field.

  6. ADAPTION OF NONSTANDARD PIPING COMPONENTS INTO PRESENT DAY SEISMIC CODES

    SciTech Connect

    D. T. Clark; M. J. Russell; R. E. Spears; S. R. Jensen

    2009-07-01

    With spiraling energy demand and flat energy supply, there is a need to extend the life of older nuclear reactors. This sometimes requires that existing systems be evaluated to present day seismic codes. Older reactors built in the 1960s and early 1970s often used fabricated piping components that were code compliant during their initial construction time period, but are outside the standard parameters of present-day piping codes. There are several approaches available to the analyst in evaluating these non-standard components to modern codes. The simplest approach is to use the flexibility factors and stress indices for similar standard components with the assumption that the non-standard component’s flexibility factors and stress indices will be very similar. This approach can require significant engineering judgment. A more rational approach available in Section III of the ASME Boiler and Pressure Vessel Code, which is the subject of this paper, involves calculation of flexibility factors using finite element analysis of the non-standard component. Such analysis allows modeling of geometric and material nonlinearities. Flexibility factors based on these analyses are sensitive to the load magnitudes used in their calculation, load magnitudes that need to be consistent with those produced by the linear system analyses where the flexibility factors are applied. This can lead to iteration, since the magnitude of the loads produced by the linear system analysis depend on the magnitude of the flexibility factors. After the loading applied to the nonstandard component finite element model has been matched to loads produced by the associated linear system model, the component finite element model can then be used to evaluate the performance of the component under the loads with the nonlinear analysis provisions of the Code, should the load levels lead to calculated stresses in excess of Allowable stresses. This paper details the application of component-level finite

  7. On the Stability of Liquid Water on Present Day Mars

    NASA Technical Reports Server (NTRS)

    Haberle, Robert M.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The mean annual surface pressure and temperature on present day Mars do not allow for the long term stability of liquid water on the surface. However, theoretical arguments have been advanced that suggest liquid water could form in transient events even though it would not be in equilibrium with the environment. Using a Mars General Circulation Model, we calculate where and for how long the surface pressure and surface temperature meet the minimum requirements for this metastability of liquid water. These requirements are that the pressure and temperature must be above the triple point of water, but below its boiling point. We find that there are five regions on Mars where these requirements are periodically satisfied: in the near equatorial regions of Amazonis, Arabia, and Elysium, and in the Hellas and Argyre impact basins. Whether liquid water ever forms in these regions depends on the availability of ice and heat, and on the evaporation rate. The latter is poorly understood for low pressure CO2 environments, but is likely to be so high that melting occurs rarely, if at all. However, in the relatively recent past, surface pressures may have been higher than they are today perhaps by as much as a factor of 2 or 3. Under these circumstances melting would have been easier to achieve. We plan to undertake laboratory experiments to better understand the potential for melting in low pressure environments.

  8. Phosphorus Necrosis of the Jaw: A Present-day Study

    PubMed Central

    Hughes, J. P. W.; Baron, R.; Buckland, D. H.; Cooke, M. A.; Craig, J. D.; Duffield, D. P.; Grosart, A. W.; Parkes, P. W. J.; Porter, A.

    1962-01-01

    A historical note on the aetiology of phossy jaw shows that present-day knowledge is little greater than it was a century ago. The varied clinical course of the disease is described together with a report of 10 classical cases not previously reported. Six cases, not amounting to true necrosis but in which healing after dental extraction was delayed, and described, and mention is made of the noticeable differences in the oral state and appearances of tartar of healthy workmen exposed to phosphorus compared with healthy workmen not exposed. But no systematic differences of any kind were found in the incidence of general infections, fractures of bones, haematological findings, and biochemical studies of blood and urine in two groups of healthy men most exposed and least exposed to phosphorous in the same factory. An intensive study in hospital of a case of classical necrosis showed no departure from normal, except delayed healing following bone biopsy from the iliac crest, and a reversed polymorphonuclear/lymphocyte ratio. In the discussion the time of onset of necrosis after first exposure to phosphorus, clinical and radiological diagnosis, the organisms present, personal susceptibility, the appearance of the sequestra, and regeneration of bone are considered. An up-to-date note on prevention of the disease is given, although this has met with only partial success. Some persons are highly susceptible and, whilst complete protection is impossible in the light of our present knowledge, early diagnosis and modern treatment have robbed the disease of its terrible manifestations of Victorian times and turned it into a minor, although often uncomfortable complaint, with little or no resulting disability. Images PMID:14449812

  9. Present Day Activity of South Polar Gullies on Mars

    NASA Astrophysics Data System (ADS)

    Raack, J.; Reiss, D.; Ruesch, O.; Hiesinger, H.

    2012-04-01

    Here we report on clearly identified seasonal changes of gullies observed within the last two martian years (MY) on slopes of a south polar pit, which is located in a filled crater (diameter ~54 km) north of Sisyphi Cavi at ~68.5°S and ~1.5°E. Using new high-resolution imaging (High Resolution Imaging Science Experiment, HiRISE), temperature (Thermal Emission Spectrometer, TES) and spectral data (Compact Reconnaissance Imaging Spectrometer for Mars, CRISM; Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité, OMEGA), we analyzed the exact timing of changes of gullies and detect the possible medium (CO2, H2O or dry) and mechanism which initiate present day gully activity. Two locations in the study region with clear modifications of gullies were identified in MY 29 between LS 226° and LS 247° and between LS 209° and LS 247°. In MY 30 changes occur in both locations between LS 218° and LS 249°. Modifications are the formation of a new small apron and new deposits within the channel, both associated with the deposition of dark material. Erosion in gully alcoves or channels was not observed. TES data show temperatures between ~180 and ~240 K within the period of gully modifications. Maximum temperatures in the region rise up to ~285 K between LS ~270° and ~310°. Spectral data show a CO2-cover of the study region until LS 227°. CO2-ice free surface are spectrally observed for the first time at LS 249°. H2O was not spectrally detected in the study region and a mixture of CO2 and H2O as presented in [1] cannot be clearly detected. Unfortunately, there are no spectral data available between LS 227° and 249°. Modifications of gullies imply seasonal volatile activity. The activity can be narrowed down to occur between LS 226° and 247° at mean temperatures between ~180 and ~240 K. This is in the range of temperatures where CO2 sublimates back into the atmosphere. Based on the temperature range, the most likely candidate for the observed new

  10. Modelling economic losses of historic and present-day high-impact winter windstorms in Switzerland

    DOE PAGESBeta

    Welker, Christoph; Martius, Olivia; Stucki, Peter; Bresch, David; Dierer, Silke; Bronnimann, Stefan

    2016-03-30

    This study investigates the wind gusts and associated economic loss patterns of high-impact winter windstorms in Switzerland between 1871 and 2011. A novel approach for simulating windstorm-related gusts and losses at regional to local scales is applied to a sample of 84 windstorms. The approach involves the dynamical downscaling of the Twentieth Century Reanalysis (20CR) ensemble mean to 3-km horizontal grid size using the Weather Research and Forecasting (WRF) model. Economic losses are simulated at municipal level for present-day asset distribution based on the downscaled (parameterised) wind gusts at high spatiotemporal resolution using the open-source impact model climada. A comparisonmore » with insurance loss data for two recent windstorms ("Lothar'' in 1999, "Joachim'' in 2011) indicates that the loss simulation allows to realistically simulate the spatial patterns of windstorm losses. The loss amplitude is strongly underestimated for 'Lothar', while it is in reasonable agreement for 'Joachim'. Possible reasons are discussed. Uncertainties concerning the loss simulation arise from the wind gust estimation method applied; estimates can differ considerably among the different methods, in particular over high orography. Furthermore, the quality of the loss simulation is affected by the underlying simplified assumptions regarding the distribution of assets and their susceptibilities to damage. For the whole windstorm sample, composite averages of simulated wind gust speed and loss are computed. Both composites reveal high values for the densely populated Swiss Plateau and lower values for south-eastern Switzerland; metropolitan areas stand out in the loss composite. Eight of the top 10 events concerning the losses simulated for present-day asset distribution and summed over all Swiss municipalities occurred after 1950. Furthermore, it remains uncertain whether this is due to decadal-scale changes of winter windstorms in Switzerland or merely due to a possible

  11. The evolution of galaxies from primeval irregulars to present-day ellipticals.

    PubMed

    Mori, Masao; Umemura, Masayuki

    2006-03-30

    Galaxy formation is believed to proceed in a 'bottom up' manner, starting with the formation of small clumps of gas and stars that then merge hierarchically into giant systems. The baryonic gas loses thermal energy by radiative cooling and falls towards the centres of the new galaxies, while supernovae blow gas out. Any realistic model therefore requires a proper treatment of these processes, but hitherto this has been far from satisfactory. Here we report a simulation that follows evolution from the earliest stages of galaxy formation through the period of dynamical relaxation, at which point the resulting galaxy is in its final form. The bubble structures of gas revealed in our simulation (for times of less than 3 x 10(8) years) resemble closely high-redshift Lyman-alpha emitters. After 10(9) years, these bodies are dominated by stellar continuum radiation and then resemble the Lyman break galaxies, which are high-redshift star-forming galaxies. At this point, the abundance of elements heavier than helium ('metallicity') appears to be solar. After 1.3 x 10(10) years, these galaxies resemble present-day ellipticals. PMID:16572164

  12. Diversity and biogeography of present-day magnetotactic bacteria in eastern China

    NASA Astrophysics Data System (ADS)

    Lin, W.; Wang, Y.; Pan, Y.

    2012-12-01

    A number of microorganisms are able to biomineralize iron minerals. Among them, magnetotactic bacteria (MTB) mineralize intracellular membrane-enveloped magnetite and/or greigite, known as magnetosomes that help cells to swim along the Earth's magnetic field. In recent years, MTB have become an attractive model system for investigating the biogeomagnetism. The occurrence of MTB has been reported in aquatic environments from freshwater to marine ecosystems. And, fossil magnetosomes are found to be potential carriers of natural remanent magnetization and indicators of paleoenvironmental changes. However, their distribution across heterogeneous habitats remains unclear. Here we report the diversity and biogeography of MTB from more than 20 locations from freshwater to saline habitats in eastern China. Great morphological variability was observed in MTB communities through light and transmission electron microscope observation. Phylogenetic analysis based on 16S rRNA genes has revealed that identified MTB belonged to the Alphaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, and the phylum Nitrospirae. The overall composition of MTB communities was compared, and we found a restricted distribution of MTB communities across a large spatial scale with pronounced endemicity. Variation partitioning analyses indicated that the biogeography of MTB is relatively more influenced by environmental factors (e.g., salinity, sulfate, total iron, Eh, and temperature) than geographic distance. More interestingly, we found, for the first time, that the strength of the Earth's magnetic field appears to influence the biogeography of MTB, implying an impact of geophysical effects on these microorganisms. Our results infer that MTB community represents a biogeographic distribution across the studied heterogeneous environments. Knowledge of the present-day MTB biogeography may be applied towards the reconstruction of paleo-environments and assessment of contribution of bacterial

  13. Present-day secular variations in the zonal harmonics of earth's geopotential

    NASA Technical Reports Server (NTRS)

    Mitrovica, J. X.; Peltier, W. R.

    1993-01-01

    The mathematical formulation required for predicting secular variation in the geopotential is developed for the case of a spherically symmetric, self-gravitating, viscoelastic earth model and an arbitrary surface load which can include a gravitational self-consistent ocean loading component. The theory is specifically applied to predict the present-day secular variation in the zonal harmonics of the geopotenial arising from the surface mass loading associated with the late Pleistocene glacial cycles. A procedure is outlined in which predictions of the present-day geopotential signal due to the late Pleistocene glacial cycles may be used to derive bounds on the net present-day mass flux from the Antarctic and Greenland ice sheets to the local oceans.

  14. Present-day Mars' water cycle: new views and blind perspectives

    NASA Astrophysics Data System (ADS)

    Montmessin, F.; Smith, M. D.; Fedorova, A.; Langevin, Y.; Mellon, M.

    2012-09-01

    Addressing recent cimate changes on Mars necessarily requires a succesful representation of present-day Mars water cycle. Decades of observations and modeling efforts have been conducted that now allow to elaborate a new, yet incomplete, picture, of the seasonal activity of water on Mars. This presentation explores the various observational and theoretical studies that have been conducted to date, and attempts to present a clear and detailed explanation of the major physical mechanisms that command the seasonal and geographical variability of present-day Mars water cycle, as inferred from the combined analysis of measurements and climate model simulations. Remaining issues and enigmae will be presented as well.

  15. Historical trauma as public narrative: A conceptual review of how history impacts present-day health

    PubMed Central

    Mohatt, Nathaniel Vincent; Thompson, Azure B.; Thai, Nghi D.; Tebes, Jacob Kraemer

    2014-01-01

    Theories of historical trauma increasingly appear in the literature on individual and community health, especially in relation to racial and ethnic minority populations and groups that experience significant health disparities. As a consequence of this rapid growth, the literature on historical trauma comprises disparate terminology and research approaches. This critical review integrates this literature in order to specify theoretical mechanisms that explain how historical trauma influences the health of individuals and communities. We argue that historical trauma functions as a public narrative for particular groups or communities that connects present-day experiences and circumstances to the trauma so as to influence health. Treating historical trauma as a public narrative shifts the research discourse away from an exclusive search for past causal variables that influence health to identifying how present-day experiences, their corresponding narratives, and their health impacts are connected to public narratives of historical trauma for a particular group or community. We discuss how the connection between historical trauma and present-day experiences, related narratives, and health impacts may function as a source of present-day distress as well as resilience. PMID:24561774

  16. Present-day Stress Pattern of Turkey from Inversion of Updated Earthquake Focal Mechanism Catalogue

    NASA Astrophysics Data System (ADS)

    Özacar, A.

    2011-12-01

    Active tectonic setting of Turkey is characterized by different stress regimes. In order to analyze present-day tectonic stresses throughout the country, all available earthquake focal mechanisms with updated locations reported by the International Seismological Center (ISC) and national catalogues are compiled between 34° - 43° latitudes and 25° - 46° longitudes. Focal mechanisms of earthquakes with multiple solutions are chosen based on their reliability and consistency with the local tectonic setting. The resultant database which includes 1391 events occurred during the period 1909 - 2010 with magnitudes ranging from 2.0 to 8.0 and depths reaching up to 165 km, constitutes the base information for better active fault characterization in seismic hazard analyses. Using this catalogue, the pressure-tension axes, maximum-minimum horizontal stress axes, and tectonic stress regime of each earthquake are determined following the World Stress Map (WSM) project guidelines and analyzed separately for crustal and intermediate depth earthquakes. During stress inversion, crustal events are grouped in 36 and intermediate depth events in 2 distinct regions on the basis of their geographical proximity, kinematic homogeneity and tectonic setting to minimize the amount of heterogeneity and map the variations in the stress field. In the following stage, results of independent stress inversions including orientations of the three principal compressive stresses (σ1 = maximum, σ2 = intermediate, and σ3 = minimum), ratio of stress magnitudes (σ2 - σ3 / σ1 - σ3), and dominant stress regimes, are analyzed along with seismicity recorded by national seismic networks and previously mapped active faults. Our results reveal widespread strike-slip faulting in the crust throughout Turkey including North Anatolian Fault Zone, North Aegean Trough, Pliny-Strabo Trenches, Paphos Transform Fault, Tuzgölü Fault, East Anatolian Fault Zone, and East Anatolian Plateau. The regions

  17. Present-day kinematics of the Rivera plate and implications for tectonics in southwestern Mexico

    NASA Astrophysics Data System (ADS)

    Demets, Charles; Stein, Seth

    1990-12-01

    A model for the present-day motion of the Rivera plate relative to the North America, Cocos, and Pacific plates is derived using new data from the Pacific-Rivera rise and Rivera transform fault, together with new estimates of Pacific-Rivera motions. The results are combined with the closure-consistent NUVEL-1 global plate motion model of DeMets et al. (1990) to examine present-day deformation in southwestern Mexico. The analysis addresses several questions raised in previous studies of the Rivera plate. Namely, do plate motion data from the northern East Pacific rise require a distinct Rivera plate? Do plate kinematic data require the subduction of the Rivera plate along the seismically quiescent Acapulco trench? If so, what does the predicted subduction rate imply about the earthquake recurrence interval in the Jalisco region of southwestern Mexico?

  18. Mantle rheology and satellite signatures from present-day glacial forcings

    NASA Technical Reports Server (NTRS)

    Sabadini, Roberto; Yuen, David A.; Gasperini, Paolo

    1988-01-01

    Changes in the long-wavelength region of the earth's gravity field resulting from both present-day glacial discharges and the possible growth of the Antarctic ice sheet are considered. Significant differences in the responses between the Maxell and Burger body rheologies are found for time spans of less than 100 years. The quantitative model for predicting the secular variations of the gravitational potential, and means for incorporating glacial forcings, are described. Results are given for the excitation of the degree two harmonics. It is suggested that detailed satellite monitoring of present-day ice movements in conjunction with geodetic satellite missions may provide a reasonable alternative for the esimation of deep mantle viscosity.

  19. Present-day kinematics of the Rivera plate and implications for tectonics in southwestern Mexico

    NASA Technical Reports Server (NTRS)

    Demets, Charles; Stein, Seth

    1990-01-01

    A model for the present-day motion of the Rivera plate relative to the North America, Cocos, and Pacific plates is derived using new data from the Pacific-Rivera rise and Rivera transform fault, together with new estimates of Pacific-Rivera motions. The results are combined with the closure-consistent NUVEL-1 global plate motion model of DeMets et al. (1990) to examine present-day deformation in southwestern Mexico. The analysis addresses several questions raised in previous studies of the Rivera plate. Namely, do plate motion data from the northern East Pacific rise require a distinct Rivera plate? Do plate kinematic data require the subduction of the Rivera plate along the seismically quiescent Acapulco trench? If so, what does the predicted subduction rate imply about the earthquake recurrence interval in the Jalisco region of southwestern Mexico?

  20. Convergence, divergence, and parallelism in marine biodiversity trends: Integrating present-day and fossil data

    NASA Astrophysics Data System (ADS)

    Huang, Shan; Roy, Kaustuv; Valentine, James W.; Jablonski, David

    2015-04-01

    Paleontological data provide essential insights into the processes shaping the spatial distribution of present-day biodiversity. Here, we combine biogeographic data with the fossil record to investigate the roles of parallelism (similar diversities reached via changes from similar starting points), convergence (similar diversities reached from different starting points), and divergence in shaping the present-day latitudinal diversity gradients of marine bivalves along the two North American coasts. Although both faunas show the expected overall poleward decline in species richness, the trends differ between the coasts, and the discrepancies are not explained simply by present-day temperature differences. Instead, the fossil record indicates that both coasts have declined in overall diversity over the past 3 My, but the western Atlantic fauna suffered more severe Pliocene-Pleistocene extinction than did the eastern Pacific. Tropical western Atlantic diversity remains lower than the eastern Pacific, but warm temperate western Atlantic diversity recovered to exceed that of the temperate eastern Pacific, either through immigration or in situ origination. At the clade level, bivalve families shared by the two coasts followed a variety of paths toward today's diversities. The drivers of these lineage-level differences remain unclear, but species with broad geographic ranges during the Pliocene were more likely than geographically restricted species to persist in the temperate zone, suggesting that past differences in geographic range sizes among clades may underlie between-coast contrasts. More detailed comparative work on regional extinction intensities and selectivities, and subsequent recoveries (by in situ speciation or immigration), is needed to better understand present-day diversity patterns and model future changes.

  1. Convergence, divergence, and parallelism in marine biodiversity trends: Integrating present-day and fossil data

    PubMed Central

    Huang, Shan; Roy, Kaustuv; Valentine, James W.; Jablonski, David

    2015-01-01

    Paleontological data provide essential insights into the processes shaping the spatial distribution of present-day biodiversity. Here, we combine biogeographic data with the fossil record to investigate the roles of parallelism (similar diversities reached via changes from similar starting points), convergence (similar diversities reached from different starting points), and divergence in shaping the present-day latitudinal diversity gradients of marine bivalves along the two North American coasts. Although both faunas show the expected overall poleward decline in species richness, the trends differ between the coasts, and the discrepancies are not explained simply by present-day temperature differences. Instead, the fossil record indicates that both coasts have declined in overall diversity over the past 3 My, but the western Atlantic fauna suffered more severe Pliocene−Pleistocene extinction than did the eastern Pacific. Tropical western Atlantic diversity remains lower than the eastern Pacific, but warm temperate western Atlantic diversity recovered to exceed that of the temperate eastern Pacific, either through immigration or in situ origination. At the clade level, bivalve families shared by the two coasts followed a variety of paths toward today’s diversities. The drivers of these lineage-level differences remain unclear, but species with broad geographic ranges during the Pliocene were more likely than geographically restricted species to persist in the temperate zone, suggesting that past differences in geographic range sizes among clades may underlie between-coast contrasts. More detailed comparative work on regional extinction intensities and selectivities, and subsequent recoveries (by in situ speciation or immigration), is needed to better understand present-day diversity patterns and model future changes. PMID:25901312

  2. Convergence, divergence, and parallelism in marine biodiversity trends: Integrating present-day and fossil data.

    PubMed

    Huang, Shan; Roy, Kaustuv; Valentine, James W; Jablonski, David

    2015-04-21

    Paleontological data provide essential insights into the processes shaping the spatial distribution of present-day biodiversity. Here, we combine biogeographic data with the fossil record to investigate the roles of parallelism (similar diversities reached via changes from similar starting points), convergence (similar diversities reached from different starting points), and divergence in shaping the present-day latitudinal diversity gradients of marine bivalves along the two North American coasts. Although both faunas show the expected overall poleward decline in species richness, the trends differ between the coasts, and the discrepancies are not explained simply by present-day temperature differences. Instead, the fossil record indicates that both coasts have declined in overall diversity over the past 3 My, but the western Atlantic fauna suffered more severe Pliocene-Pleistocene extinction than did the eastern Pacific. Tropical western Atlantic diversity remains lower than the eastern Pacific, but warm temperate western Atlantic diversity recovered to exceed that of the temperate eastern Pacific, either through immigration or in situ origination. At the clade level, bivalve families shared by the two coasts followed a variety of paths toward today's diversities. The drivers of these lineage-level differences remain unclear, but species with broad geographic ranges during the Pliocene were more likely than geographically restricted species to persist in the temperate zone, suggesting that past differences in geographic range sizes among clades may underlie between-coast contrasts. More detailed comparative work on regional extinction intensities and selectivities, and subsequent recoveries (by in situ speciation or immigration), is needed to better understand present-day diversity patterns and model future changes. PMID:25901312

  3. Multimodel intercomparison of preindustrial, present-day and future tropospheric OH and methane lifetime

    NASA Astrophysics Data System (ADS)

    Voulgarakis, A.; Naik, V.; Archibald, A. T.; Collins, B.; Dentener, F. J.; Josse, B.; Lamarque, J.; Prather, M. J.; Shindell, D. T.; Stevenson, D. S.; Sudo, K.; Szopa, S.; Takemura, T.; Wild, O.; Williams, J.; Young, P. J.; Zeng, G.

    2011-12-01

    The oxidizing capacity of the atmosphere heavily depends on the levels of the hydroxyl radical (OH) and its geographical distribution. OH removes a wide range of pollutants and non-CO2 greenhouse gases from the atmosphere. It controls the atmospheric lifetime of methane, the most important anthropogenic greenhouse gas after carbon dioxide, and is key to the formation of tropospheric ozone and aerosols. Because of its crucial role, it is important to understand how OH has changed from preindustrial to present day, and how it may change in the future in response to different emission scenarios. Here, we analyze simulations performed for the Atmospheric Chemistry and Climate Modeling Intercomparison Project (ACCMIP), in support of the IPCC AR5, to investigate the changes in global and regional OH and consequent changes in methane lifetime between 1850 and 2100. The ACCMIP project includes a variety of chemistry-climate models, which were run for the historical period (1850 to present-day) and for the future (present-day to 2100) following the different Representative Concentration Pathways (RCPs). A wide range of chemical output from these simulations is expected to contribute to our understanding of chemistry-climate interactions. We identify changes in OH and methane lifetime, and also the key drivers of these changes, including the ratio between different emissions (NOx, CO, VOCs), changes in water vapor, as well as changes in the ozone photolysis rate and factors affecting it (stratospheric ozone, aerosols and clouds).

  4. Minimal effects of latitude on present-day speciation rates in New World birds.

    PubMed

    Rabosky, Daniel L; Title, Pascal O; Huang, Huateng

    2015-06-22

    The tropics contain far greater numbers of species than temperate regions, suggesting that rates of species formation might differ systematically between tropical and non-tropical areas. We tested this hypothesis by reconstructing the history of speciation in New World (NW) land birds using BAMM, a Bayesian framework for modelling complex evolutionary dynamics on phylogenetic trees. We estimated marginal distributions of present-day speciation rates for each of 2571 species of birds. The present-day rate of speciation varies approximately 30-fold across NW birds, but there is no difference in the rate distributions for tropical and temperate taxa. Using macroevolutionary cohort analysis, we demonstrate that clades with high tropical membership do not produce species more rapidly than temperate clades. For nearly any value of present-day speciation rate, there are far more species in the tropics than the temperate zone. Any effects of latitude on speciation rate are marginal in comparison to the dramatic variation in rates among clades. PMID:26019156

  5. Simulating present-day and future air quality as climate changes: Model evaluation

    NASA Astrophysics Data System (ADS)

    Dawson, John P.; Racherla, Pavan N.; Lynn, Barry H.; Adams, Peter J.; Pandis, Spyros N.

    The global-regional climate-air pollution modeling system (GRE-CAPS) has been developed, coupling an existing general circulation model/chemical transport model (GCM/CTM), a regional meteorological model, and a regional chemical transport model. This system is intended to enable studies of the effects of changes in climate, intercontinental transport, and emissions on regional and urban air quality. The GRE-CAPS system consists of the GISS II' GCM/CTM, the MM5 regional meteorological model, and the PMCAMx regional CTM. The modeling system is evaluated for the present day, with comparisons between model-predicted, measured ozone, and speciated PM 2.5 concentrations. The ability of the model to predict present-day concentrations of ozone and PM 2.5 is compared to that of PMCAMx when used for retrospective modeling. Comparisons between model-predicted temperatures and precipitation are also made. The model was used to simulate five present-day Januaries and six present-day Julys. The biases and errors in GRE-CAPS-predicted ozone concentrations were similar to those of PMCAMx when used for standard retrospective modeling. The fractional biases in mean daily peak ozone concentration and mean daily maximum 8-h average ozone concentration are both <10%. The model-predicted distribution of peak hourly and daily maximum 8-h average values agreed rather well with the measured distribution. There is less agreement between the model and measurements in the number of hours with ozone mixing ratios >70 or 80 ppb, though this is also the case with standard PMCAMx modeling. The predictions of PM 2.5 concentrations by GRE-CAPS were also of similar quality to those of PMCAMx driven by historical meteorology. The fractional biases in the predictions of total PM 2.5, sulfate, ammonium, and nitrate were all <25% in both January and July. The model agrees well with organic PM 2.5 measurements from the IMPROVE network, though there is less agreement with measurements from the STN network

  6. Association of vWA and TPOX Polymorphisms with Venous Thrombosis in Mexican Mestizos

    PubMed Central

    Meraz-Ríos, Marco Antonio; Majluf-Cruz, Abraham; Santana, Carla; Noris, Gino; Camacho-Mejorado, Rafael; Acosta-Saavedra, Leonor C.; Calderón-Aranda, Emma S.; Hernández-Juárez, Jesús; Magaña, Jonathan J.; Gómez, Rocío

    2014-01-01

    Objective. Venous thromboembolism (VTE) is a multifactorial disorder and, worldwide, the most important cause of morbidity and mortality. Genetic factors play a critical role in its aetiology. Microsatellites are the most important source of human genetic variation having more phenotypic effect than many single nucleotide polymorphisms. Hence, we evaluate a possible relationship between VTE and the genetic variants in von Willebrand factor, human alpha fibrinogen, and human thyroid peroxidase microsatellites to identify possible diagnostic markers. Methods. Genotypes were obtained from 177 patients with VTE and 531 nonrelated individuals using validated genotyping methods. The allelic frequencies were compared; Bayesian methods were used to correct population stratification to avoid spurious associations. Results. The vWA-18, TPOX-9, and TPOX-12 alleles were significantly associated with VTE. Moreover, subjects bearing the combination vWA-18/TPOX-12 loci exhibited doubled risk for VTE (95% CI = 1.02–3.64), whereas the combination vWA-18/TPOX-9 showed an OR = 10 (95% CI = 4.93–21.49). Conclusions. The vWA and TPOX microsatellites are good candidate biomarkers in venous thromboembolism diseases and could help to elucidate their origins. Additionally, these polymorphisms could become useful markers for genetic studies of VTE in the Mexican population; however, further studies should be done owing that this data only show preliminary evidence. PMID:25250329

  7. Utilizing Present-Day Stable Water Isotopes to Improve Paleoclimate Records from the Southeast (USA)

    NASA Astrophysics Data System (ADS)

    McKay, K. K.; Lambert, W. J.

    2015-12-01

    Present-day water isotope data are used to help interpret climate (paleo-rainfall) proxies archived in the geologic record, which can then aid in the creation of General Circulation Models (GCM). The Southeast (USA) is under-represented with respect to present-day measurement of water isotopes and high-resolution paleoclimate records, thus GCMs must extrapolate data for the region. We will evaluate water isotope data (δ18O, δD) collected and analyzed at The University of Alabama (33°13'N, 87°33'W) since June 2005. The monitoring station, central to the Southeast, was established to provide long-term water isotope data needed for reconstructing paleo-rainfall records of the region. Proxy data (e.g., δ18Ocalcite) archived in speleothems have been demonstrated to provide trustworthy information about past climate conditions; however, present-day monitoring of both local rainfall and cave dripwater are crucial. The decade-long (June 2005 - May 2015) rainfall record allows for the establishment of the relationship between water isotopes (δ18O, δD) and monthly air temperature, rainfall amount, as well as the general differences between summer and winter rainfall. Dripwater from Cathedral Caverns (34°34'N, 86°13'W), located in northeastern Alabama, has been sampled at a monthly resolution since January 2015 to determine if the water chemistry in the cave represents an annual mean for the rainfall or if it is seasonally biased. The ultimate goal of this study is to better understand how atmospheric air currents (specifically the strength/position of the Polar Jet Stream, PJS), and hence rainfall in the Southeast, varied during past periods of relative warming (e.g., Dansgaard-Oeschger events) and cooling (e.g., Heinrich events) of the Northern Hemisphere atmosphere. Future GCMs will be improved if a reliable high-resolution paleo-rainfall record can be produced for the Southeast.

  8. Evaluation of a wetland methane emission parameterization for present-day and Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Basu, A.; Schultz, M. G.; Francois, L.

    2012-04-01

    Wetlands are the largest natural source of atmospheric methane and presumably contribute ~25-40% to its annual budget (~500 Tg). However, there remain considerable uncertainties in estimation of global wetlands and their methane emissivity, given the large domain of their vegetation and hydrological characteristics. In this study, we describe the development of a wetland methane emission model in conjunction with global wetland parameterization at seasonal resolution. Contrary to most of the other modeling studies, our model is based on a simple parameterization and also readily adaptable to different paleo climatic scenarios, in which the role of methane is still largely unexplored. Wetlands with a strong climatic sensitivity are perceived to be a key factor in past changes of atmospheric methane concentration, e.g. the double fold increase since the Last Glacial Maximum (LGM). The present parameterization is primarily based on CARAIB, a large scale dynamic vegetation model designed to study the role of vegetation in the global carbon cycle. Its hydrological module is adept at simulating soil water and several associated hydrological fluxes over various biome types. Our model parameterization uses three basic drivers from CARAIB: soil water, soil temperature and soil carbon content along with high resolution terrain slope data. The emission model is included in the chemistry climate model ECHAM5-MOZ for present day and also used in LGM methane simulations. The model results are evaluated in comparison with atmospheric methane observations from the NOAA-CMDL flask network and ice core records for LGM. We obtained the present day wetland methane source to be 153 Tg/year, which lies near the lower edge of model assumptions. We also discuss the uncertainties of the present day simulation and the impact of emission scaling on atmospheric concentration. The latitudinal distribution of other major methane sources, uncertainties in their budget and their potential role in

  9. Functional Analyses of Transcription Factor Binding Sites that Differ between Present-Day and Archaic Humans.

    PubMed

    Weyer, Sven; Pääbo, Svante

    2016-02-01

    We analyze 25 previously identified transcription factor binding sites that carry DNA sequence changes that are present in all or nearly all present-day humans, yet occur in the ancestral state in Neandertals and Denisovans, the closest evolutionary relatives of humans. When the ancestral and derived forms of the transcription factor binding sites are tested using reporter constructs in 3 neuronal cell lines, the activity of 12 of the derived versions of transcription factor binding sites differ from the respective ancestral variants. This suggests that the majority of this class of evolutionary differences between modern humans and Neandertals may affect gene expression in at least some tissue or cell type. PMID:26454764

  10. Functional Analyses of Transcription Factor Binding Sites that Differ between Present-Day and Archaic Humans

    PubMed Central

    Weyer, Sven; Pääbo, Svante

    2016-01-01

    We analyze 25 previously identified transcription factor binding sites that carry DNA sequence changes that are present in all or nearly all present-day humans, yet occur in the ancestral state in Neandertals and Denisovans, the closest evolutionary relatives of humans. When the ancestral and derived forms of the transcription factor binding sites are tested using reporter constructs in 3 neuronal cell lines, the activity of 12 of the derived versions of transcription factor binding sites differ from the respective ancestral variants. This suggests that the majority of this class of evolutionary differences between modern humans and Neandertals may affect gene expression in at least some tissue or cell type. PMID:26454764

  11. Present-day Exposures of Water Ice in the Northern Mid-latitudes of Mars

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Kanner, Lisa C.

    2007-01-01

    Water ice is exposed in the martian north polar cap, but is rarely exposed beyond the cap boundary. Orbital gamma ray spectrometry data strongly imply the presence of water ice within meters of the surface at latitudes north of approximately 60deg. We have examined mid-latitude areas of the northern plains displaying residual ice-rich layers, and report evidence of present-day surface exposures of water ice. These exposures, if confirmed, could con-strain the latitudinal and temporal stability of surface ice on Mars.

  12. Present-day strain rates and dynamics of the East African Rift

    NASA Astrophysics Data System (ADS)

    Stamps, D. S.; Flesch, L. M.; Calais, E.

    2009-04-01

    The forces and physical processes at work during continental rifting remain to be fully understood and quantified. We investigate the balance of large-scale forces affecting present-day rifting in East Africa using a thin sheet approach to quantify strain rates and deviatoric stresses. We develop a strain rate model constrained by a combination of GPS-derived kinematic models and seismic moment tensors (CMT catalog) for our region of interest. We estimate a total deviatoric stress field by combining (1) stresses caused by gravitational potential energy (GPE) gradients within the crust and (2) a buoyancy signal present in the topography that we use to compute stresses. To estimate internal body forces, we assume crustal thicknesses and lateral density variations modeled in Crust 2.0 (G. Laske and G. Masters, http://mahi.ucsd.edu/Gabi/sediment.html, 2000). In our preferred model of deviatoric stresses, we estimate and remove the dynamic topography buoyancy signal by allowing the mantle lithosphere density to vary, compensating the lithosphere to a given reference depth. To test the reliability of our total deviatoric stress field, we compare tensor patterns of deviatoric stresses, with and without contributions from the mantle, to tensor patterns from kinematic deformation indicators. Our results to date suggest that horizontal buoyancy forces arising from variable crustal thicknesses and lateral density variations within the lithosphere contribute significantly to the diverging plate boundary forces of the EAR but do not account for the entire budget of force needed to produce present-day deformation.

  13. Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

    NASA Astrophysics Data System (ADS)

    Staller, Alejandra; Martínez-Díaz, José Jesús; Benito, Belén; Alonso-Henar, Jorge; Hernández, Douglas; Hernández-Rey, Román; Díaz, Manuel

    2016-02-01

    This paper presents the results and conclusions obtained from new GPS data compiled along the El Salvador Fault Zone (ESFZ). We calculated a GPS-derived horizontal velocity field representing the present-day crustal deformation rates in the ESFZ based on the analysis of 30 GPS campaign stations of the ZFESNet network, measured over a 4.5 year period from 2007 to 2012. The velocity field and subsequent strain rate analysis clearly indicate dextral strike-slip tectonics with extensional component throughout the ESFZ. Our results suggest that the boundary between the Salvadoran forearc and Caribbean blocks is a deformation zone which varies along the fault zone. We estimate that the movement between the two blocks is at least ~ 12 mm yr- 1. From west to east, this movement is variably distributed between faults or segments of the ESFZ. We propose a kinematic model with three main blocks; the Western, Central and Eastern blocks delimited by major faults. For the first time, we were able to provide a quantitative measure of the present-day horizontal geodetic slip rate of the main segments of ESFZ, ranging from ~ 2 mm yr- 1 in the east segment to ~ 8 mm yr- 1, in the west and central segments. This study contributes new kinematic and slip rate data that should be used to update and improve the seismic hazard assessments in northern Central America.

  14. A non-tectonic origin for the present day stress field in the sedimentary Paris Basin

    NASA Astrophysics Data System (ADS)

    Cornet, Francois; Magnenet, Vincent

    2016-04-01

    The large scale stress patterns observed in intraplate area is generally considered to result from far-field boundary forces that drive plate tectonics. However, no present day deformation has been detected in the Paris Basin, yet significant deviatoric stresses are measured in limestone formations observed above soft argillite layers encountered in this region at depths close to 500m. Further, the pore pressure measured in the argillite is larger than that measured in the surrounding permeable zones. These observations suggest a presently active source of stress in this sedimentary system. We propose that this stress is not related to tectonics but to pressure solution effects activated by pore pressure transients. These transients develop in the natural fracture system that affects the limestone formations. They are linked to climatic variations and involve periods that range from thousands to hundreds of thousands years. This mechanism generates time-dependent shear stresses in soft formations and explains overpressures observed in the very low permeability argillite. This mechanism may be modeled by different visco-elastic behaviors for the various formations. It outlines the influence of time dependent material properties on the present day stress field. These results imply that the viscoelastic properties of sedimentary formations raise a strong difficulty for extrapolating measured surface deformations to basement rocks in domains of very slow tectonics.

  15. EXPECTED NUMBER OF MASSIVE GALAXY RELICS IN THE PRESENT DAY UNIVERSE

    SciTech Connect

    Quilis, Vicent; Trujillo, Ignacio

    2013-08-10

    The number of present day massive galaxies that have survived untouched since their formation at high-z is an important observational constraint to the hierarchical galaxy formation models. Using three different semianalytical models based on the Millenium simulation, we quantify the expected fraction and number densities of the massive galaxies that form at z > 2 and have evolved in stellar mass less than 10% and 30%. We find that only a small fraction of the massive galaxies that already formed at z {approx} 2 have remained almost unaltered since their formation (<2% with {Delta}M{sub *}/M{sub *} < 0.1 and <8% with {Delta}M{sub *}/M{sub *} < 0.3). These fractions correspond to the following number densities of massive relics in the present day universe: {approx}1.2 Multiplication-Sign 10{sup -6} Mpc{sup -3} for {Delta}M{sub *}/M{sub *} < 0.1 and {approx}5.7 Multiplication-Sign 10{sup -6} Mpc{sup -3} for {Delta}M{sub *}/M{sub *} < 0.3. The observed number of relic candidates found in the nearby universe is rather uncertain today (with uncertainties up to a factor of {approx}100), preventing us from establishing firm conclusions about the ability of current theoretical expectations to predict such an important number.

  16. Present-day and future global bottom-up ship emission inventories including polar routes.

    PubMed

    Paxian, Andreas; Eyring, Veronika; Beer, Winfried; Sausen, Robert; Wright, Claire

    2010-02-15

    We present a global bottom-up ship emission algorithm that calculates fuel consumption, emissions, and vessel traffic densities for present-day (2006) and two future scenarios (2050) considering the opening of Arctic polar routes due to projected sea ice decline. Ship movements and actual ship engine power per individual ship from Lloyd's Marine Intelligence Unit (LMIU) ship statistics for six months in 2006 and further mean engine data from literature serve as input. The developed SeaKLIM algorithm automatically finds the most probable shipping route for each combination of start and destination port of a certain ship movement by calculating the shortest path on a predefined model grid while considering land masses, sea ice, shipping canal sizes, and climatological mean wave heights. The resulting present-day ship activity agrees well with observations. The global fuel consumption of 221 Mt in 2006 lies in the range of previously published inventories when undercounting of ship numbers in the LMIU movement database (40,055 vessels) is considered. Extrapolated to 2007 and ship numbers per ship type of the recent International Maritime Organization (IMO) estimate (100,214 vessels), a fuel consumption of 349 Mt is calculated which is in good agreement with the IMO total of 333 Mt. The future scenarios show Arctic polar routes with regional fuel consumption on the Northeast and Northwest Passage increasing by factors of up to 9 and 13 until 2050, respectively. PMID:20088494

  17. Pacific variability under present-day and Middle Miocene boundary conditions

    NASA Astrophysics Data System (ADS)

    Krapp, Mario; Jungclaus, Johann H.

    2015-05-01

    We use the coupled climate model MPI-ESM to show that for higher CO2 levels the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) merge into a single mode of Pacific variability, regardless of present-day or Middle Miocene (~15 Ma) topographic boundary conditions. Hence, topographic differences—determining the landscape of past climates—play a smaller role for Pacific variability than previously thought. We attribute the single variability mode to resonance between these two oscillation patterns. In order to estimate the strength of the resonance we compute the spectral power of the ENSO and PDO time series and their coherence. We find that for both Middle Miocene and present-day topographic conditions, higher CO2 forcing leads to stronger resonance between ENSO and PDO. Our results show that (1) stronger CO2 forcing enhances Pacific variability resulting in stronger "atmospheric bridge" and that (2) past climates are likely to exhibit Pacific variability corresponding either to ENSO, PDO, or our proposed single mode.

  18. Future droughts in Global Climate Models and adaptation strategies from regional present-day analogues

    NASA Astrophysics Data System (ADS)

    Orlowsky, B.; Seneviratne, S. I.

    2012-04-01

    Droughts are among the most impacting phenomena of a changing climate, affecting agricultural productivity and human health. They can furthermore interact with and amplify other climatic extreme events such as heat waves. Our analysis of the CMIP5 ensemble of GCM simulations identifies several hot spots of aggravating droughts in coming decades, such as the Mediterranean, parts of the Southern US and North East Brazil, which also compare well with increasing stress from heat waves. However, as we show by a comparison of drought indices, the exact pattern can substantially depend on the index choice. In some regions of the developing world which are particularly vulnerable to droughts, e.g. Central Africa, this uncertainty is further increased by a high disagreement between the GCMs. In a second step, we perform an analogue search which, for a given target region, identifies regions which under present-day climate show drought conditions that are similar to the projected future drought conditions of the target region. For example, the future conditions in the Mediterranean are found to be analogue to the present-day conditions in parts of the US, Central Asia or Australia. Information from web resources on climate change adaptation and agricultural practices for the identified similar regions are then assessed in the context of the target region as potential guidelines for adaptation. Thus combining the temporal and spatial dimension helps to transfer local climate adaptation knowledge to other regions, where it is expected to become relevant in the future.

  19. Past- and present-day Madden-Julian Oscillation in CNRM-CM5

    NASA Astrophysics Data System (ADS)

    Song, Eun-Ji; Seo, Kyong-Hwan

    2016-04-01

    Madden-Julian Oscillation (MJO) in the past (nineteenth century) and present day (twentieth century) is examined using preindustrial and historical experiments of Centre National de Recherches Météorologiques-Coupled Models, version 5 (CNRM-CM5) in Coupled Model Intercomparison Project Phase 5 (CMIP5). The present-day MJO is stronger than the past MJO by 33% and it is ~10% more frequent. In particular, the MJO phases 4-7 signifying deep convection situated over the Maritime continent and western Pacific (WP) are considerably enhanced. These changes are due mainly to greenhouse gas forcing with little impact from nature forcing. Dynamical mechanisms for this change are investigated. A peculiar strengthening of MJO over WP comes from increased basic-state sea surface temperature (SST) over the Central Pacific (CP) and EP. The increase in precipitation over WP results from both the response to enhanced SST over CP and the inverted Walker circulation induced by the EP and CP SST increase. The latter causes a pair of anticyclonic Rossby waves straddling the equator, leading to moisture convergence over WP.

  20. Chemical interactions between the present-day Martian atmosphere and surface minerals

    NASA Technical Reports Server (NTRS)

    Prinn, Ronald; Fegley, Bruce

    1987-01-01

    Thermochemical and photochemical reactions between surface minerals and present-day atmospheric constituents are predicted to produce microscopic effects on the surfaces of mineral grains. Relevant reactions hypothesized in the literature include conversions of silicates and volcanic glasses to clay minerals, conversion of ferrous to ferric compounds, and formation of carbonates, nitrates, and sulfates. These types of surface-atmosphere interactions are important for addressing issues such as chemical weathering of minerals, biological potential of the surface environment, and atmospheric stability in both present and past Martian epochs. It is emphasized that the product of these reactions will be observable and interpretable on the microscopic surface layers of Martian surface rocks using modern techniques with obvious implications for sample return from Mars. Macroscopic products of chemical weathering reactions in past Martian epochs are also expected in Martian surface material. These products are expected not only as a result of reactions similar to those proceeding today but also due to aqueous reactions in past epochs in which liquid water was putatively present. It may prove very difficult or impossible however to determine definitively from the relic macroscopic product alone either the exact weathering process which led to its formation or the identity of its weathered parent mineral. The enormous advantages of studying Martian chemical weathering by investigating the microscopic products of present-day chemical reactions on sample surfaces are very apparent.

  1. Chemical interactions between the present-day Martian atmosphere and surface minerals: Implications for sample return

    NASA Technical Reports Server (NTRS)

    Prinn, Ronald; Fegley, Bruce

    1988-01-01

    Thermochemical and photochemical reactions between surface minerals and present-day atmospheric constituents are predicted to produce microscopic effects on the surface of mineral grains. Relevant reactions hypothesized in the literature include conversions of silicates and volcanic glasses to clay minerals, conversion of ferrous to ferric compounds, and formation of carbonates, nitrates, and sulfates. These types of surface-atmosphere weathering of minerals, biological potential of the surface environment, and atmospheric stability in both present and past Martian epochs. It is emphasized that the product of these reactions will be observable and interpretable on the microscopic surface layers of Martian surface rocks using modern techniques with obvious implications for sample return from Mars. Macroscopic products of chemical weathering reactions in past Martian epochs are also expected in Martian surface materials. These products are expected not only as a result of reactions similar to those proceeding today but also due to aqueous reactions in past epochs in which liquid water was putatively present. It may prove very difficult or impossible, however, to determine definitively from the relic macroscopic product alone either the exact weathering process which led to its formation of the identity of its weathering parent mineral. The enormous advantages of studying the Martian chemical weathering by investigating the microscopic products of present-day chemical reactions on sample surfaces are very apparent.

  2. Assessment of present day geomorphological dynamics to decipher landscape evolution around the Paleolithic sites of Melka Kunture, Ethiopia

    NASA Astrophysics Data System (ADS)

    Maerker, Michael; Schillaci, Calogero; Melis, Rita; Mussi, Margherita

    2014-05-01

    The area of Melka Kunture (central Ethiopia) is one of the most important clusters of Paleolithic sites in Eastern Africa. The archaeological record spans from c. 1.7 Ma onwards, with a number of stratified occurrences of Oldowan, Acheulean, Middle Stone Age and Late Stone Age industries, together with faunal remains and human fossils. However, the archaeological sites are endangered by flooding and soil erosion. The main excavation area lies close to the convergence of the Awash river with the Atabella river, one of the main tributaries of the upper Awash catchment. In the semi-arid Ethiopian highlands, gully networks develop especially in the vicinity of the active and inactive river meanders. Various erosion processes are linked to specific driving factors such as the rainfall regime, the land use/cover changes and vertic soils with a specific hydrological behaviour. It was documented in the field and by previous research that the origin of most of the man made erosion channels is due to animal pathways and car tracks. However, paleolandscape features increase the general erosion risk. Former wetland areas and deposition zones are particularly affected by soil erosion processes. Hence, the spatial distribution and characteristics of present day geomorphic processes also reveal information on the paleolandscape. In order to assess landscape evolution and present day geomorphologic dynamics, we mapped the geomorphology describing in detail the present-day slope processes at a 10.000 scale. We performed a detailed terrain analysis based on high resolution DEMs such as SRTM-X with 25m resolution and ALOS/PRISM with 10m resolution to characterize the main erosion processes and surface runoff dynamics. The latter ones are simulated using a Soil Conservation Service Curve Number method. Landuse was delineated for a larger area using ASTER 25m multispectral data. Finally, using calibrated topographic indices and a simple hydrological model we were able to detect and

  3. Present-Day Surface Changes on Mars: Implications for Recent Climate Variability and Habitability

    NASA Astrophysics Data System (ADS)

    McEwen, A. S.; Dundas, C. M.; Diniega, S.; Byrne, S.; Bridges, N. T.; Hansen, C. J.

    2012-12-01

    With the high-resolution and repeat-image capability of MRO/HiRISE, we have been documenting present-day surface activity. This activity includes seasonal defrosting (spots, fans, etc.), changes in polar deposits, new impacts, migrating sand dunes, enlargement of gullies, and a variety of slope flows. What does this tell us about possible environmental change and habitability? Perhaps the key result is that previous suggestions of recent climate change on Mars may have been somewhat exaggerated. One such suggestion is that the enlargement of pits in the south polar residual cap indicates present-day global warming. However, recent models of continuous sublimation and redeposition of the CO2 predict a suite of landforms that have been observed to exist today (Byrne, 2009, AREPS 37, 535). Another suggestion is that mid-latitude gullies formed by melting snow or shallow ice after a recent period of high obliquity, but HiRISE observations have shown rapid and widespread gully activity in the present climate (Diniega et al., 2010, Geology 38, 1047; Dundas et al., 2012, Icarus 220, 124; Dundas et al., this conference). Likewise, suggestions that Mars needed a significantly higher atmospheric density to explain the presence of well-preserved sand dunes have been countered by observations of widespread current activity (Bridges et al., 2012, Geology 40, 31; Bridges et al., 2012, Nature 485, 339). These observations do not rule out significantly different past climate conditions but do suggest that their effects were less pronounced, at least in recent times. There are features that do not appear active today; one example is the transverse aeolian ridges. Also, the mid-latitude icy lobate flows and ice-rich mantles have not shown current activity, appear to have partially sublimated, and are likely remnants of recent past climates. Ground ice excavated by new craters is observed closer to the equator than predicted for the present atmospheric water vapor content, but

  4. Three-dimensional instantaneous dynamics modeling of present-day Aegean subduction

    NASA Astrophysics Data System (ADS)

    Glerum, Anne; Thieulot, Cedric; Pranger, Casper; van Hinsbergen, Douwe; Fraters, Menno; Spakman, Wim

    2015-04-01

    The Aegean region (Eastern Mediterranean) is exemplary of the interaction between crustal tectonics, plate motion, subduction and mantle flow: African subduction underneath the region has been continuous for at least the last 100 My, leading to about 2100-2500 km of subducted lithosphere residing in the mantle (van Hinsbergen et al., 2005). During this subduction, decoupled upper continental and oceanic crust accreted into a wedge of stacked nappes. In turn, these nappes have been significantly extended, predominantly during the last 25 My, due to the retreat of the African slab relative to Eurasia (van Hinsbergen and Schmid, 2012). As a first step to better understanding the coupling of the tectonic evolution of the crust and the underlying mantle dynamics, we are developing 3-D numerical models of the instantaneous dynamics of the present-day Aegean subduction system using the finite element code ASPECT (Kronbichler et al., 2012). The instantaneous models are set up with initial slab geometries derived from tomography and realistic plate boundary configurations and incorporate the major crustal weak zones of the overriding plate. Our modeling results in predictions of flow fields and stress, strain rate and rotation rate fields for the present-day tectonic setting of the Aegean region. By comparing our various model predictions to the widely available observations, such as focal mechanisms, GPS velocities and seismic anisotropy, we aim at an improved understanding of how mantle flow, subduction morphology and possibly slab segmentation, as well as the rheological behavior of the overriding plate, control present-day tectonic deformation. We expect to show preliminary results of this comparison. Kronbichler, M., Heister, T. and Bangerth, W. (2012), High Accuracy Mantle Convection Simulation through Modern Numerical Methods, Geophysical Journal International, 191, 12-29. Van Hinsbergen, D. J. J., Hafkenscheid, E., Spakman, W., Meulenkamp, J. E. and Wortel, R. (2005

  5. Cloud properties in the present-day tropical climate: EC-EARTH model biases

    NASA Astrophysics Data System (ADS)

    Lacagnina, C.; Selten, F.

    2012-04-01

    Observations are compared with the observed SST forced and coupled simulation performed by the EC-EARTH climate model. We use different diagnostic tools to investigate model biases in simulating marine cloud properties at different spatial and time scales in the present-day (1985 to 2001) tropical climate. The model underestimates the thick low-cloud amount and their contribution to the reflection of the solar radiation. In general, most of the simulated cloud types are too bright. As a result, the net cloud cooling effect is often overestimated, except over the subsidence cold pools. Furthermore, our model fails to reproduce the correlations between low-cloud fraction and mid-tropospheric pressure velocity (ω500) and SST changes during El Niño. In addition, some indications lead to infer EC-EARTH does not properly reproduce the impact of the Walker circulation shifts on the CRF fluctuations in the interannual variability.

  6. Ancient human genomes suggest three ancestral populations for present-day Europeans.

    PubMed

    Lazaridis, Iosif; Patterson, Nick; Mittnik, Alissa; Renaud, Gabriel; Mallick, Swapan; Kirsanow, Karola; Sudmant, Peter H; Schraiber, Joshua G; Castellano, Sergi; Lipson, Mark; Berger, Bonnie; Economou, Christos; Bollongino, Ruth; Fu, Qiaomei; Bos, Kirsten I; Nordenfelt, Susanne; Li, Heng; de Filippo, Cesare; Prüfer, Kay; Sawyer, Susanna; Posth, Cosimo; Haak, Wolfgang; Hallgren, Fredrik; Fornander, Elin; Rohland, Nadin; Delsate, Dominique; Francken, Michael; Guinet, Jean-Michel; Wahl, Joachim; Ayodo, George; Babiker, Hamza A; Bailliet, Graciela; Balanovska, Elena; Balanovsky, Oleg; Barrantes, Ramiro; Bedoya, Gabriel; Ben-Ami, Haim; Bene, Judit; Berrada, Fouad; Bravi, Claudio M; Brisighelli, Francesca; Busby, George B J; Cali, Francesco; Churnosov, Mikhail; Cole, David E C; Corach, Daniel; Damba, Larissa; van Driem, George; Dryomov, Stanislav; Dugoujon, Jean-Michel; Fedorova, Sardana A; Gallego Romero, Irene; Gubina, Marina; Hammer, Michael; Henn, Brenna M; Hervig, Tor; Hodoglugil, Ugur; Jha, Aashish R; Karachanak-Yankova, Sena; Khusainova, Rita; Khusnutdinova, Elza; Kittles, Rick; Kivisild, Toomas; Klitz, William; Kučinskas, Vaidutis; Kushniarevich, Alena; Laredj, Leila; Litvinov, Sergey; Loukidis, Theologos; Mahley, Robert W; Melegh, Béla; Metspalu, Ene; Molina, Julio; Mountain, Joanna; Näkkäläjärvi, Klemetti; Nesheva, Desislava; Nyambo, Thomas; Osipova, Ludmila; Parik, Jüri; Platonov, Fedor; Posukh, Olga; Romano, Valentino; Rothhammer, Francisco; Rudan, Igor; Ruizbakiev, Ruslan; Sahakyan, Hovhannes; Sajantila, Antti; Salas, Antonio; Starikovskaya, Elena B; Tarekegn, Ayele; Toncheva, Draga; Turdikulova, Shahlo; Uktveryte, Ingrida; Utevska, Olga; Vasquez, René; Villena, Mercedes; Voevoda, Mikhail; Winkler, Cheryl A; Yepiskoposyan, Levon; Zalloua, Pierre; Zemunik, Tatijana; Cooper, Alan; Capelli, Cristian; Thomas, Mark G; Ruiz-Linares, Andres; Tishkoff, Sarah A; Singh, Lalji; Thangaraj, Kumarasamy; Villems, Richard; Comas, David; Sukernik, Rem; Metspalu, Mait; Meyer, Matthias; Eichler, Evan E; Burger, Joachim; Slatkin, Montgomery; Pääbo, Svante; Kelso, Janet; Reich, David; Krause, Johannes

    2014-09-18

    We sequenced the genomes of a ∼7,000-year-old farmer from Germany and eight ∼8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians, who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these populations' deep relationships and show that early European farmers had ∼44% ancestry from a 'basal Eurasian' population that split before the diversification of other non-African lineages. PMID:25230663

  7. Meteoritic parent bodies - Nature, number, size and relation to present-day asteroids

    NASA Technical Reports Server (NTRS)

    Lipschutz, Michael E.; Gaffey, Michael J.; Pellas, Paul

    1989-01-01

    The relationship between meteoritic parent bodies and the present-day asteroids is discussed. Results on oxygen isotopic signatures and chemical distinctions among meteorite classes indicate that meteorites derive from a small number of parent bodies relative to the number of asteroids. The spectral properties of the ordinary chondrites and similar inclusions in meteoritic breccias differ from those of the abundant S asteroids (with no process known that can account for these differences); the closest spectral analogs of these chondrites are the rare near-earth Q-type asteroids. These facts lead to the question of why abundant meteorites have rare asteroidal analogs, while the abundant asteroids have rare meteoritic analogs. This question constitutes a prime topic for future studies.

  8. Modelling economic losses of historic and present-day high-impact winter storms in Switzerland

    NASA Astrophysics Data System (ADS)

    Welker, Christoph; Martius, Olivia; Stucki, Peter; Bresch, David; Dierer, Silke; Brönnimann, Stefan

    2015-04-01

    Windstorms can cause significant financial damage and they rank among the most hazardous meteorological hazards in Switzerland. Risk associated with windstorms involves the combination of hazardous weather conditions, such as high wind gust speeds, and socio-economic factors, such as the distribution of assets as well as their susceptibilities to damage. A sophisticated risk assessment is important in a wide range of areas and has benefits for e.g. the insurance industry. However, a sophisticated risk assessment needs a large sample of storm events for which high-resolution, quantitative meteorological and/or loss data are available. Latter is typically an aggravating factor. For present-day windstorms in Switzerland, the data basis is generally sufficient to describe the meteorological development and wind forces as well as the associated impacts. In contrast, historic windstorms are usually described by graphical depictions of the event and/or by weather and loss reports. The information on historic weather events is overall sparse and the available historic weather and loss reports mostly do not provide quantitative information. It has primarily been the field of activity of environmental historians to study historic weather extremes and their impacts. Furthermore, the scarce availability of atmospheric datasets reaching back sufficiently in time has so far limited the analysis of historic weather events. The Twentieth Century Reanalysis (20CR) ensemble dataset, a global atmospheric reanalysis currently spanning 1871 to 2012, offers potentially a very valuable resource for the analysis of historic weather events. However, the 2°×2° latitude-longitude grid of the 20CR is too coarse to realistically represent the complex orography of Switzerland, which has considerable ramifications for the representation of smaller-scale features of the surface wind field influenced by the local orography. Using the 20CR as a starting point, this study illustrates a method to

  9. Larval therapy from antiquity to the present day: mechanisms of action, clinical applications and future potential

    PubMed Central

    Whitaker, Iain S; Twine, Christopher; Whitaker, Michael J; Welck, Mathew; Brown, Charles S; Shandall, Ahmed

    2007-01-01

    When modern medicine fails, it is often useful to draw ideas from ancient treatments. The therapeutic use of fly larvae to debride necrotic tissue, also known as larval therapy, maggot debridement therapy or biosurgery, dates back to the beginnings of civilisation. Despite repeatedly falling out of favour largely because of patient intolerance to the treatment, the practice of larval therapy is increasing around the world because of its efficacy, safety and simplicity. Clinical indications for larval treatment are varied, but, in particular, are wounds infected with multidrug‐resistant bacteria and the presence of significant co‐morbidities precluding surgical intervention. The flies most often used in larval therapy are the facultative calliphorids, with the greenbottle blowfly (Lucilia sericata) being the most widely used species. This review summarises the fascinating and turbulent history of larval therapy from its origin to the present day, including mechanisms of action and evidence for its clinical applications. It also explores future research directions. PMID:17551073

  10. Pole of rotating analysis of present-day Juan de Fuca plate motion

    NASA Technical Reports Server (NTRS)

    Nishimura, C.; Wilson, D. S.; Hey, R. N.

    1984-01-01

    Convergence rates between the Juan de Fuca and North American plates are calculated by means of their relative, present-day pole of rotation. A method of calculating the propagation of errors in addition to the instantaneous poles of rotation is also formulated and applied to determine the Euler pole for Pacific-Juan de Fuca. This pole is vectorially added to previously published poles for North America-Pacific and 'hot spot'-Pacific to obtain North America-Juan de Fuca and 'hot spot'-Juan de Fuca, respectively. The errors associated with these resultant poles are determined by propagating the errors of the two summed angular velocity vectors. Under the assumption that hot spots are fixed with respect to a mantle reference frame, the average absolute velocity of the Juan de Puca plate is computed at approximately 15 mm/yr, thereby making it the slowest-moving of the oceanic plates.

  11. The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans.

    PubMed

    Sankararaman, Sriram; Mallick, Swapan; Patterson, Nick; Reich, David

    2016-05-01

    Some present-day humans derive up to ∼5% [1] of their ancestry from archaic Denisovans, an even larger proportion than the ∼2% from Neanderthals [2]. We developed methods that can disambiguate the locations of segments of Denisovan and Neanderthal ancestry in present-day humans and applied them to 257 high-coverage genomes from 120 diverse populations, among which were 20 individual Oceanians with high Denisovan ancestry [3]. In Oceanians, the average size of Denisovan fragments is larger than Neanderthal fragments, implying a more recent average date of Denisovan admixture in the history of these populations (p = 0.00004). We document more Denisovan ancestry in South Asia than is expected based on existing models of history, reflecting a previously undocumented mixture related to archaic humans (p = 0.0013). Denisovan ancestry, just like Neanderthal ancestry, has been deleterious on a modern human genetic background, as reflected by its depletion near genes. Finally, the reduction of both archaic ancestries is especially pronounced on chromosome X and near genes more highly expressed in testes than other tissues (p = 1.2 × 10(-7) to 3.2 × 10(-7) for Denisovan and 2.2 × 10(-3) to 2.9 × 10(-3) for Neanderthal ancestry even after controlling for differences in level of selective constraint across gene classes). This suggests that reduced male fertility may be a general feature of mixtures of human populations diverged by >500,000 years. PMID:27032491

  12. Is Present Day Continental Deformation Nearly Plate-Like? If so, Why?

    NASA Astrophysics Data System (ADS)

    Thatcher, W.

    2001-12-01

    Some indicators of deformation (seismicity, late Cenozoic faulting, regional topographic relief) suggest broad deformation zones. However, space geodetic mappings of current movements and Holocene fault distributions often show straining focussed in very narrow zones. Conventional wisdom has it that continental deformation is spread over broad regions while straining of oceanic lithosphere occurs in narrow zones. Here I present evidence, largely from recent GPS surveys, suggesting present day continental deformation is actually occurring in a largely plate-like manner through the relative motions of a small number of micro-plates within each deforming zone, sometimes perturbed by isolated zones of deformation driven by local lithospheric density gradients. How can this be so? I speculate that this behavior is caused by the inherent lateral heterogeneity of continental lithosphere and by frictional and ductile weakening and strengthening mechanisms that promote focussed deformation that migrates with time. Qualitative indications of active deformation can sometimes be misleading. In many active regions erosion and tectonism are in balance and very low rates of slip on inclined faults can generate significant steady-state topography. However, in currently inactive regions, erosion rates are very low, much less than rates of vertical movement in even moderately active deforming zones. Therefore landscape relief provides evidence for current activity but preserves it over long periods, millions to tens of millions of years (Ma) (e.g. Alps, Rocky Mountains). Secondly, background seismicity is a qualitative measure of tectonic activity and only the largest earthquakes contribute significantly to representative long term deformation rates, so the spatial distribution of all smaller events can be misleading. Finally, many mappings of `active' faults encompass features up to several Ma old that are not necessarily representative of current activity. In contrast, late

  13. How large are present-day heat flow variations across Mars' surface?

    NASA Astrophysics Data System (ADS)

    Plesa, Ana-Catalina; Tosi, Nicola; Grott, Matthias; Breuer, Doris

    2015-04-01

    The upcoming InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission, to be launched in 2016, will carry the first in-situ Martian heat flow measurement and provide an important baseline to constrain the present-day heat budget of the planet and, in turn, the thermal and chemical evolution of its interior. Currently, the Earth and the Moon are the only bodies on which in-situ surface heat flow measurements have been performed. Here, strong spatial variations of the surface heat flow are primarily caused by plate tectonics and the heterogeneous distribution of heat producing elements over the surface (e.g., the so-called Procellarum KREEP Terrane PKT on the lunar nearside). In the absence of plate-tectonics and large-scale geochemical anomalies, on Mars, surface heat flow is expected to vary less with geological location, being mainly influenced by variations in the thickness and HPE content of the crust [1], and by mantle plumes [2]. We have tested this assumption by running thermal evolution models for Mars in 3D spherical geometry, using the mantle convection code Gaia [3]. In our calculations, we employ a crust of fixed thickness with a north-south dichotomy in crustal thickness, a low conductivity compared to the mantle and enriched in radiogenic heat producing elements. Our results show that including compressibility effects, phase transitions and different core sizes, surface heat flow variations are mainly dominated by the crust contribution, unless the mantle viscosity increases more than three orders of magnitude with depth. In the latter case, heat flow variations due to mantle upwellings are ~ 8 mW/m2 relative to surface average and remain confined to limited surface regions. Both surface heat flow variations on Mars obtained from numerical models and the heat flow measurement planned for the InSight mission will permit to address the question of a possible plume underneath Elysium and also to test the feasibility

  14. Present-day serpentinization in the Tablelands, Gros Morne National Park, Newfoundland: a Mars Analogue Site

    NASA Astrophysics Data System (ADS)

    Szponar, N.; Morrill, P. L.; Brazelton, W. J.; Schrenk, M. O.; Bower, D. M.; Steele, A.

    2010-12-01

    Serpentinization - a reaction between water and ultramafic rock (derived from the mantle) - is suspected to be a source of hydrocarbons such as methane on Mars. Through the hydration of ultramafic rock, this reaction produces hydrogen (H2) gas and reducing conditions necessary for abiogenic hydrocarbon synthesis, while also producing conditions amendable for the production of methane through microbial chemoautotrophic pathways. Mars analogue sites of present-day serpentinization can be used to determine what geochemical measurements are required for determining the reactions responsible for the methane in the Martian atmosphere. On Earth few locations that are known to exhibit active serpentinization are easily accessible. One such location is found in the Tablelands at Gros Morne National Park, Newfoundland. Peridotite rocks similar to those found on Mars dominate the Tablelands thus making the Tablelands an important analogue site for potential ecosystems on Mars. Present-day serpentinization is evidenced by fluid seeps characterized by highly alkaline (pH 11 to 12) and highly reducing (as low as -820 mV) conditions, travertine and the presence of dissolved methane. These fluids contain high concentrations of Ca2+ (~5.00x104ppb) compared to freshwater inputs (~ 1.00x103) and react at the surface with atmospheric CO2 producing travertine deposits (as CaCO3 precipitate). Dissolved H2 gas produced abiogenically through the serpentinization reaction also provides copious geofuels, which can be used for chemosynthesis. Preliminary data has shown that microbial life lives in the high pH springs of the Tablelands. Ongoing studies of targeted compounds including phospholipid fatty acids and ether-linked lipids are being used to determine the microbial community compositions and verify the occurrence of Bacteria and Archaea in these fluids. An important question is also the source of the serpentinized fluid seeps. Hydrogen (δ2H) and oxygen (δ18O) isotopes of these

  15. Present-day stress-field in the Cooper basin of Australia: implications for petroleum exploration

    NASA Astrophysics Data System (ADS)

    Backé, G.; King, R.

    2010-12-01

    The Cooper Basin is located in centre part of the Australian continent, 5000km away from the nearest plate boundary. This Late Carboniferous to Middle Triassic basin is the largest onshore sedimentary basin producing oil and gas in Australia - mostly by fraccing tight reservoirs. Thus, an extensive database is available for studying the in-situ stress field in the basin. Previous studies have shown a significant variability if the stress field across the basin. However, the development of the mostly tight prospects require a good understanding of the structure of the reservoirs, mechanical properties of the stratigraphy, fracture geometry and density, in-situ stress field and fracture stimulation strategies in order to maximise the production This study provides new in-situ stress data from borehole breakouts and drilling-induced tensile fractures, along with a description of the fractures present along the well trajectory. The geometry of the natural fault and fracture network is interpreted from 3D seismic data, and compared to the well data. Finally, we performed a series of numeric simulation to test the fault and fracture stability in the present-day stress field. These data and our interpretation are used to evaluate the geomechanical properties of the Cooper Basin. This method is reproducible to other oil-bearing basins around the world, but is also applicable to the development of engineered geothermal reservoir or evaluation of carbon dioxide storage site.

  16. Global hotspots in the present-day distribution of ancient animal and plant lineages.

    PubMed

    Procheş, Şerban; Ramdhani, Syd; Perera, Sandun J; Ali, Jason R; Gairola, Sanjay

    2015-01-01

    The current distribution of biotic lineages that emerged in the deep time has both theoretical and practical implications, in particular for understanding the processes that have forged present-day biodiversity and informing local and regional-scale conservation efforts. To date however, there has been no examination of such patterns globally across taxa and geological time. Here we map the diversity of selected extant seed plant and tetrapod vertebrate lineages that were already in existence either in the latest Triassic or latest Cretaceous. For Triassic-age lineages, we find concentrations in several regions - both tropical and temperate - parts of North America, Europe, East and South-east Asia, northern South America, and New Zealand. With Cretaceous-age lineages, high values are relatively uniformly distributed across the tropics, with peak the values along the Andes, in South-east Asia and Queensland, but also in the temperate Cape Mountains. These patterns result from a combination of factors, including land area, geographic isolation, climate stability and mass extinction survival ability. While the need to protect many of these lineages has been long recognised, a spatially-explicit approach is critical for understanding and maintaining the factors responsible for their persistence, and this will need to be taken forward across finer scales. PMID:26498226

  17. The history of time and frequency from antiquity to the present day

    NASA Astrophysics Data System (ADS)

    Levine, Judah

    2016-04-01

    I will discuss the evolution of the definitions of time, time interval, and frequency from antiquity to the present day. The earliest definitions of these parameters were based on a time interval defined by widely observed apparent astronomical phenomena, so that techniques of time distribution were not necessary. With this definition, both time, as measured by clocks, and frequency, as realized by some device, were derived quantities. On the other hand, the fundamental parameter today is a frequency based on the properties of atoms, so that the situation is reversed and time and time interval are now derived quantities. I will discuss the evolution of this transition and its consequences. In addition, the international standards of both time and frequency are currently realized by combining the data from a large number of devices located at many different laboratories, and this combination depends on (and is often limited by) measurements of the times of clocks located at widely-separated laboratories. I will discuss how these measurements are performed and how the techniques have evolved over time.

  18. Simulation of Net Infiltration for Present-Day and Potential Future Climates

    SciTech Connect

    D. Levitt

    2004-11-09

    The purpose of this model report is to document the infiltration model used to estimate upper-bound, mean, and lower-bound spatially-distributed average annual net infiltration rates for present-day and potential future climates at Yucca Mountain, Nevada. Net infiltration is the component of infiltrated precipitation, snowmelt, or surface water run-on that has percolated below the zone of evapotranspiration as defined by the depth of the effective root zone. The estimates of net infiltration are primarily used for defining the upper boundary condition for the site-scale three-dimensional unsaturated zone (UZ) model. The UZ flow model is one of several process models abstracted by the total system performance assessment (TSPA) model used to evaluate performance of the repository at Yucca Mountain, Nevada. The net-infiltration model is important for assessing repository-system performance because output from this model provides the upper boundary condition for the UZ flow model used to generate flow fields; water percolating downward from the UZ will be the principal means by which radionuclides are potentially released to the saturated zone (SZ). The SZ is the principal pathway to the biosphere where the reasonably maximally exposed individual (RMEI) is exposed to radionuclides.

  19. Improved Present Day Euler Vector for the Sierra Nevada Block Using GPS

    NASA Astrophysics Data System (ADS)

    Psencik, K. O.; Dixon, T. H.; Schmalzle, G.; McQuarrie, N.; McCaffery, R.

    2006-12-01

    We present a new surface velocity field for California and Nevada (UM-CANVAS) and use it to solve for a new angular velocity for the rigid Sierra Nevada-Great Valley block. We use all publicly available GPS data for this region, from both continuous (CGPS) and episodic campaign (EGPS) sites. All data were re-processed to create a consistent velocity field. Site velocities are referenced to both stable North America and the central Basin and Range. The Sierra Nevada block is a relatively long, narrow block, bounded on the west by the San Andreas Fault, on the east by a complex fault system comprising the Eastern California Shear Zone and the Walker Lane Belt, and on the south by the Garlock fault. The northern extent of the block is not well defined. The new data along with a strain accumulation algorithm may help to define this boundary. Published estimates for the motion of Sierra Nevada block include clockwise, counter-clockwise, and no rotation relative to stable North America; the new velocity data may also help to resolve this discrepancy. To better understand the motion of the Sierra Nevada block over time, we compare our model of present day motion to a geologic model of block motion over the last 2-3 Ma (McQuarrie and Wernicke, 2005). McQuarrie, N. and B. Wernicke, An Animated tectonic reconstruction of southwestern North America since 36 Ma. Geosphere, V.1; no.3; 147-172; 2005.

  20. Present-day deformation of northern Pakistan from Salt Ranges to Karakorum Ranges

    NASA Astrophysics Data System (ADS)

    Jouanne, F.; Awan, A.; Pêcher, A.; Kausar, A.; Mugnier, J. L.; Khan, I.; Khan, N. A.; Van Melle, J.

    2014-03-01

    Episodic GPS measurements are used to quantify the present-day velocity field in the northwestern Himalaya from the southern Pamir to the Himalayan foreland. We report large postseismic displacements following the 2005 Kashmir earthquake and several mm/yr thrusting of the central segment of the Salt Ranges and Potwar Plateau over the foreland, westward thrusting of Nanga Parbat above the Kohistan Plateau, and ~12 mm/yr SSE velocities of the Karakorum Ranges and of the Deosai and Kohistan Plateaus relative to the Indian Plate. Numerical simulations allow to determine a first approximation of slip along active faults: (1) substantial creep of ~87 mm/yr between 2006 and 2012 along the flat northeast of the Balakot-Bagh Thrust affected by the 2005 earthquake; (2) ~5 mm/yr slip of the central segment of the Salt Ranges and Potwar Plateau, whereas their western boundaries are clearly inactive over the time span covered by our measurements; (3) 13 mm/yr ductile slip along the Main Himalayan Thrust modeled by a dislocation dipping 7° northward, locked at a depth of 15 km; and (4) ~20 mm/yr slip along the shear zone forming the western boundary of Nanga Parbat, between depths of 1.6 and 6.5 km. Residuals velocities suggest the existence of left-lateral strike slip along the Jhelum Fault.

  1. Recovery of a geocentric reference frame using the present-day GPS system

    NASA Technical Reports Server (NTRS)

    Malla, Rajendra P.; Wu, Sien-Chong

    1990-01-01

    A geocentric reference frame adopts the center of mass of the earth as the origin of the coordinate axes. The center of mass of the earth is the natural and unambiguous origin of a geocentric satellite dynamical system. But in practice a kinematically obtained terrestrial reference frame may assume an origin other than the geocenter. The establishment of a geocentric reference frame, to which all relevant observations and results can be referred and in which geodynamic theories or models for the dynamic behavior of earth can be formulated, requires the ability to accurately recover a given coordinate frame origin offset from the geocenter. GPS measurements, because of their abundance and broad distribution, provide a powerful tool to obtain this origin offset in a short period of time. Two effective strategies have been devised. Data from the First Central And South America (Casa Uno) geodynamics experiment has been studied, in order to demonstrate the ability of recovering the geocenter location with present day GPS satellites and receivers.

  2. Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability

    NASA Astrophysics Data System (ADS)

    Ghan, Steven; Wang, Minghuai; Zhang, Shipeng; Ferrachat, Sylvaine; Gettelman, Andrew; Griesfeller, Jan; Kipling, Zak; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G.; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Zhang, Kai

    2016-05-01

    A large number of processes are involved in the chain from emissions of aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those processes are manifest in a number of relationships that can be expressed as factors dlnX/dlnY driving aerosol effects on cloud radiative forcing. These factors include the relationships between cloud condensation nuclei (CCN) concentration and emissions, droplet number and CCN concentration, cloud fraction and droplet number, cloud optical depth and droplet number, and cloud radiative forcing and cloud optical depth. The relationship between cloud optical depth and droplet number can be further decomposed into the sum of two terms involving the relationship of droplet effective radius and cloud liquid water path with droplet number. These relationships can be constrained using observations of recent spatial and temporal variability of these quantities. However, we are most interested in the radiative forcing since the preindustrial era. Because few relevant measurements are available from that era, relationships from recent variability have been assumed to be applicable to the preindustrial to present-day change. Our analysis of Aerosol Comparisons between Observations and Models (AeroCom) model simulations suggests that estimates of relationships from recent variability are poor constraints on relationships from anthropogenic change for some terms, with even the sign of some relationships differing in many regions. Proxies connecting recent spatial/temporal variability to anthropogenic change, or sustained measurements in regions where emissions have changed, are needed to constrain estimates of anthropogenic aerosol impacts on cloud radiative forcing.

  3. Global hotspots in the present-day distribution of ancient animal and plant lineages

    PubMed Central

    Procheş, Şerban; Ramdhani, Syd; Perera, Sandun J.; Ali, Jason R.; Gairola, Sanjay

    2015-01-01

    The current distribution of biotic lineages that emerged in the deep time has both theoretical and practical implications, in particular for understanding the processes that have forged present-day biodiversity and informing local and regional-scale conservation efforts. To date however, there has been no examination of such patterns globally across taxa and geological time. Here we map the diversity of selected extant seed plant and tetrapod vertebrate lineages that were already in existence either in the latest Triassic or latest Cretaceous. For Triassic-age linages, we find concentrations in several regions – both tropical and temperate – parts of North America, Europe, East and South-east Asia, northern South America, and New Zealand. With Cretaceous-age lineages, high values are relatively uniformly distributed across the tropics, with peak the values along the Andes, in South-east Asia and Queensland, but also in the temperate Cape Mountains. These patterns result from a combination of factors, including land area, geographic isolation, climate stability and mass extinction survival ability. While the need to protect many of these lineages has been long recognised, a spatially-explicit approach is critical for understanding and maintaining the factors responsible for their persistence, and this will need to be taken forward across finer scales. PMID:26498226

  4. Present-Day Genetic Structure of Atlantic Salmon (Salmo salar) in Icelandic Rivers and Ice-Cap Retreat Models

    PubMed Central

    Olafsson, Kristinn; Pampoulie, Christophe; Hjorleifsdottir, Sigridur; Gudjonsson, Sigurdur; Hreggvidsson, Gudmundur O.

    2014-01-01

    Due to an improved understanding of past climatological conditions, it has now become possible to study the potential concordance between former climatological models and present-day genetic structure. Genetic variability was assessed in 26 samples from different rivers of Atlantic salmon in Iceland (total of 2,352 individuals), using 15 microsatellite loci. F-statistics revealed significant differences between the majority of the populations that were sampled. Bayesian cluster analyses using both prior information and no prior information on sampling location revealed the presence of two distinguishable genetic pools - namely, the Northern (Group 1) and Southern (Group 2) regions of Iceland. Furthermore, the random permutation of different allele sizes among allelic states revealed a significant mutational component to the genetic differentiation at four microsatellite loci (SsaD144, Ssa171, SSsp2201 and SsaF3), and supported the proposition of a historical origin behind the observed variation. The estimated time of divergence, using two different ABC methods, suggested that the observed genetic pattern originated from between the Last Glacial Maximum to the Younger Dryas, which serves as additional evidence of the relative immaturity of Icelandic fish populations, on account of the re-colonisation of this young environment following the Last Glacial Maximum. Additional analyses suggested the presence of several genetic entities which were likely to originate from the original groups detected. PMID:24498283

  5. Effects of Present-Day Ice Melting on the Geodetic Measurements in Southeast Alaska

    NASA Astrophysics Data System (ADS)

    Sato, T.; Larsen, C. F.; Miura, S.; Ohta, Y.; Fujimoto, H.; Sun, W.; Sugano, T.; Kaufman, A. M.; Freymueller, J. T.

    2008-12-01

    It is known that the southeast Alaska (SE-AK) is undergoing a rapid land uplift, which is considered to be mainly due to the effect of melting of past ice, especially in the last two hundred years after the little ice age (LIA). The crustal deformation caused by the post-glacial rebound (PGR) has been clearly detected by GPS and tidal gauge measurements and modeled (Larsen et al., 2004 and 2005). On the other hand, it is considered also that the observed uplift rate is affected by the present-day ice melting (PDIM), which is considered to be the effect of recent global warming (Larsen et al., 2005; Sato et al., 2006). The displacement measurements provide us useful information to evaluate the ice-melting rate and to discuss the viscosity of the earth. However, usually, it is difficult to separate the uplift rate due to the long- term viscous response of the earth by only using displacement observations, because the two effects (i.e. the elastic and viscous deformations) are mixed in the observed data. Related to this problem, Wahr et al. (1995) demonstrated a method to separate the viscous contribution from the observed data by collocating position and gravity measurements. Considered this, since 2006, we, a joint team of Japanese and U.S. researchers are carrying out the absolute gravity (AG) measurements once a year adding to the temporal and continuous GPS observations in SE-AK. Combining the AG measurements and GPS measurements is useful because the attraction part of gravity measurement is sensitive to a mass change of the present-day ice melting, while the past-ices should have no effect to the attraction part of the observed gravity change. In this context of the discussion, precise numerical estimation of the PDIM effect is important (Sato et al., 2007). Based on the two kinds of DEM (Digital Elevation Model), i.e. one is from the 2000 Shuttle Radar Topography Mission (SRTM) and other is that from air photo dating data which were obtained in the period of

  6. Uncovering the genetic history of the present-day Greenlandic population.

    PubMed

    Moltke, Ida; Fumagalli, Matteo; Korneliussen, Thorfinn S; Crawford, Jacob E; Bjerregaard, Peter; Jørgensen, Marit E; Grarup, Niels; Gulløv, Hans Christian; Linneberg, Allan; Pedersen, Oluf; Hansen, Torben; Nielsen, Rasmus; Albrechtsen, Anders

    2015-01-01

    Because of past limitations in samples and genotyping technologies, important questions about the history of the present-day Greenlandic population remain unanswered. In an effort to answer these questions and in general investigate the genetic history of the Greenlandic population, we analyzed ∼200,000 SNPs from more than 10% of the adult Greenlandic population (n = 4,674). We found that recent gene flow from Europe has had a substantial impact on the population: more than 80% of the Greenlanders have some European ancestry (on average ∼25% of their genome). However, we also found that the amount of recent European gene flow varies across Greenland and is far smaller in the more historically isolated areas in the north and east and in the small villages in the south. Furthermore, we found that there is substantial population structure in the Inuit genetic component of the Greenlanders and that individuals from the east, west, and north can be distinguished from each other. Moreover, the genetic differences in the Inuit ancestry are consistent with a single colonization wave of the island from north to west to south to east. Although it has been speculated that there has been historical admixture between the Norse Vikings who lived in Greenland for a limited period ∼600-1,000 years ago and the Inuit, we found no evidence supporting this hypothesis. Similarly, we found no evidence supporting a previously hypothesized admixture event between the Inuit in East Greenland and the Dorset people, who lived in Greenland before the Inuit. PMID:25557782

  7. Uncovering the Genetic History of the Present-Day Greenlandic Population

    PubMed Central

    Moltke, Ida; Fumagalli, Matteo; Korneliussen, Thorfinn S.; Crawford, Jacob E.; Bjerregaard, Peter; Jørgensen, Marit E.; Grarup, Niels; Gulløv, Hans Christian; Linneberg, Allan; Pedersen, Oluf; Hansen, Torben; Nielsen, Rasmus; Albrechtsen, Anders

    2015-01-01

    Because of past limitations in samples and genotyping technologies, important questions about the history of the present-day Greenlandic population remain unanswered. In an effort to answer these questions and in general investigate the genetic history of the Greenlandic population, we analyzed ∼200,000 SNPs from more than 10% of the adult Greenlandic population (n = 4,674). We found that recent gene flow from Europe has had a substantial impact on the population: more than 80% of the Greenlanders have some European ancestry (on average ∼25% of their genome). However, we also found that the amount of recent European gene flow varies across Greenland and is far smaller in the more historically isolated areas in the north and east and in the small villages in the south. Furthermore, we found that there is substantial population structure in the Inuit genetic component of the Greenlanders and that individuals from the east, west, and north can be distinguished from each other. Moreover, the genetic differences in the Inuit ancestry are consistent with a single colonization wave of the island from north to west to south to east. Although it has been speculated that there has been historical admixture between the Norse Vikings who lived in Greenland for a limited period ∼600–1,000 years ago and the Inuit, we found no evidence supporting this hypothesis. Similarly, we found no evidence supporting a previously hypothesized admixture event between the Inuit in East Greenland and the Dorset people, who lived in Greenland before the Inuit. PMID:25557782

  8. Present-day deformation of the intra-Eurasian plate regions

    NASA Astrophysics Data System (ADS)

    Garcia Sancho, Candela; Govers, Rob; Tesauro, Magdala

    2015-04-01

    , and paleomagnetic observations, which capture present-day and long-term deformation. We discuss various causes for differences.

  9. Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability

    PubMed Central

    Ghan, Steven; Wang, Minghuai; Zhang, Shipeng; Ferrachat, Sylvaine; Gettelman, Andrew; Griesfeller, Jan; Kipling, Zak; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G.; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Zhang, Kai

    2016-01-01

    A large number of processes are involved in the chain from emissions of aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those processes are manifest in a number of relationships that can be expressed as factors dlnX/dlnY driving aerosol effects on cloud radiative forcing. These factors include the relationships between cloud condensation nuclei (CCN) concentration and emissions, droplet number and CCN concentration, cloud fraction and droplet number, cloud optical depth and droplet number, and cloud radiative forcing and cloud optical depth. The relationship between cloud optical depth and droplet number can be further decomposed into the sum of two terms involving the relationship of droplet effective radius and cloud liquid water path with droplet number. These relationships can be constrained using observations of recent spatial and temporal variability of these quantities. However, we are most interested in the radiative forcing since the preindustrial era. Because few relevant measurements are available from that era, relationships from recent variability have been assumed to be applicable to the preindustrial to present-day change. Our analysis of Aerosol Comparisons between Observations and Models (AeroCom) model simulations suggests that estimates of relationships from recent variability are poor constraints on relationships from anthropogenic change for some terms, with even the sign of some relationships differing in many regions. Proxies connecting recent spatial/temporal variability to anthropogenic change, or sustained measurements in regions where emissions have changed, are needed to constrain estimates of anthropogenic aerosol impacts on cloud radiative forcing. PMID:26921324

  10. Present-day antarctic climatology of the NCAR community climate model version 1

    SciTech Connect

    Tzeng, Renyow; Bromwich, D.H. ); Parish, T.R. )

    1993-02-01

    Five-year seasonal cycle output produced by the NCAR Community Climate Model Version 1 (CCM 1) with R15 resolution is used to evaluate the ability of the model to simulate the present-day climate of Antarctica. The model results are compared with observed horizontal syntheses and point data. Katabatic winds, surface temperatures over the continent, the circumpolar trough, the vertical motion field, the split jet stream over the Pacific Ocean, and the snowfall accumulation are analyzed. The results show that the CCM1 with R15 resolution can simulate to some extent the dynamics of Antarctic climate not only for the synoptic scale, but also for some mesoscale features. This is reflected in the zonal-mean pattern of vertical motion by the presence of two convergence centers. The finding suggests that the CCM I might also capture the split jet stream over New Zealand in winter, but the evidence is mixed. This is inferred to be due to inadequate simulation of the thermal forcing over high southern latitudes. The CCM I can also capture the phase and amplitude of the annual and semiannual variation of temperature, sea level pressure, and zonally averaged zonal (E-W) wind. That the CCM 1 can simulate some characteristics of the semiannual variation may be due to the improved radiation treatment compared to the earlier CCMO. The most dramatic shortcomings were associated with the model's anomalously large precipitation amounts at high latitudes. The simulations of cloudiness and the atmospheric heat balance are adversely affected. A greatly refined moisture budget scheme is needed to eliminate these problems and may allow the split jet-stream feature over the New Zealand area in winter to be accurately reproduced. A coupled mesoscale-CCM 1 model may be needed to simulate the feedback from mesoscale cyclones to synoptic-scale weather systems, and the katabatic wind circulation.

  11. Quantifying present-day and long-term shale weathering rates across a latitudinal climosequence

    NASA Astrophysics Data System (ADS)

    Dere, A. L. D.; Andrews, E.; White, T. S.

    2015-12-01

    A transect of shale sites was established across the Northern Hemisphere as part of the Susquehanna Shale Hills Critical Zone Observatory (SSHO) to investigate the role of climate in shale weathering. Mean annual temperature and precipitation vary across sites located in Wales, New York, Pennsylvania, Virginia, Tennessee, Alabama and Puerto Rico. Long-term weathering rates were quantified by comparing bulk soil geochemistry with original parent shale composition and cosmogenic 10Be inventories to estimate weathering duration. Present-day weathering rates were obtained by burying approximately 2 cm by 1 cm shale chips at multiple depths in soil pit walls. Shale chip samples were exhumed after two and five years of burial, washed and mass loss measured. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to determine surface chemistry and physical alteration of the recovered shale. Long-term weathering rates increase with increasing temperature across the transect. Similarly, after two years of burial, exhumed shale chip weathering rates increased from 2.9 ± 0.9 in Wales to 11.2 ± 3.7 m Ma-1 in Puerto Rico. Average weathering rates after two years of burial were similar in Virginia, Tennessee and Alabama (8.6 - 10.6 m Ma-1). Many shale chips in Alabama and Puerto Rico, however, retained soil particles even after washing, therefore total mass loss, and thus weathering rates, at these sites could be even greater. After five years of burial, mass loss across the Appalachian sites was greatest in Tennessee while weathering rates were overall generally similar to two year rates (3.0 to 12.6 m Ma-1). Evidence of physical and chemical changes, especially Na and Mg loss, from shale chip surfaces was greater on shale chips buried at warmer and wetter sites. Quantifying weathering rates as a function of climate at multiple scales will contribute to understanding the effects of global climate change on soil formation rates in the Critical

  12. A test of present-day plate geometries for northeast Asia and Japan

    NASA Technical Reports Server (NTRS)

    Demets, Charles

    1992-01-01

    Alternative geometries for the present-day configuration of plate boundaries in northeast Asia and Japan are tested using NUVEL-1 and 256 horizontal earthquake slip vectors from the Japan and northern Kuril trenches. Statistical analysis of the slip vectors is used to determine whether the North American, Eurasian, or Okhotsk plate overlies the trench. Along the northern Kuril trench, slip vectors are well-fit by the NUVEL-1 Pacific-North America Euler pole, but are poorly fit by the Pacific-Eurasia Euler pole. Results for the Japan trench are less conclusive, but suggest that much of Honshu and Hokkaido are also part of the North American plate. The simplest geometry consistent with the trench slip vectors is a geometry in which the North American plate extends south to 41 deg N, and possibly includes northern Honshu and southern Hokkaido. Although these results imply that the diffuse seismicity that connects the Lena River delta to Sakhalin Island and the eastern Sea of Japan records motion between Eurasia and North America, onshore geologic and seismic data define an additional belt of seismicity in Siberia that cannot be explained with this geometry. Assuming that these two seismic belts constitute evidence for an Okhotsk block, two published kinematic models for motion of the Okhotsk block are tested. The first model, which predicts motion of up to 15 mm/yr relative to North America, is rejected because Kuril and Japan trench slip vectors are fit more poorly than for the simpler geometry described above. The second model gives a good fit to the trench slip vectors, but only if Okhotsk-North America motion is slower than 5 mm/yr.

  13. Present-day climate of Antarctica : A study with a regional atmospheric climate model

    NASA Astrophysics Data System (ADS)

    van de Berg, W. J.

    2008-02-01

    The present-day climate of Antarctica is studied with a regional climate model. In this research, foci are the surface mass balance, i.e. the accumulation of snow on the ice cap, and the heat budget of the atmosphere above Antarctica. Insight in the surface mass balance of the Antarctic ice cap is gained by explanation, evaluation and subsequently calibration of model-simulated surface mass balance patterns using more than 1900 in situ observations. Furthermore, a method is developed to quantify the uncertainty in the local and spatially integrated surface mass balance estimate. In our study, a good correlation between the observations and model results is found, giving reliability to the results presented. The final surface mass balance estimate primarily deviates in the coastal zones of Antarctica from earlier estimates. Our results strongly suggest much higher accumulation rates than previously assumed, leading to a 15% higher overall accumulation. Unfortunately, the coastal zone is poorly covered by observations, which makes a final assessment difficult. Analysis of the heat budget of the Antarctic atmosphere clarifies the dynamics of the Antarctic boundary layer and shows the coupling to the global climate. Our results show how the boundary layer develops from the interior of Antarctica to the coast; from shallow and extremely stable to deeper, mixed but still stable. Furthermore, the effect of surface undulations on the local near surface temperature is explained. Domes and ridges have a weakening effect on the surface inversion of the temperature through enhanced divergence of the near-surface wind field. Oppositely, valleys strengthen the surface inversion. This coupling of topography and temperature causes the spatial variability of surface temperatures on scales of typical a few hundred kilometers.

  14. Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability.

    PubMed

    Ghan, Steven; Wang, Minghuai; Zhang, Shipeng; Ferrachat, Sylvaine; Gettelman, Andrew; Griesfeller, Jan; Kipling, Zak; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Zhang, Kai

    2016-05-24

    A large number of processes are involved in the chain from emissions of aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those processes are manifest in a number of relationships that can be expressed as factors dlnX/dlnY driving aerosol effects on cloud radiative forcing. These factors include the relationships between cloud condensation nuclei (CCN) concentration and emissions, droplet number and CCN concentration, cloud fraction and droplet number, cloud optical depth and droplet number, and cloud radiative forcing and cloud optical depth. The relationship between cloud optical depth and droplet number can be further decomposed into the sum of two terms involving the relationship of droplet effective radius and cloud liquid water path with droplet number. These relationships can be constrained using observations of recent spatial and temporal variability of these quantities. However, we are most interested in the radiative forcing since the preindustrial era. Because few relevant measurements are available from that era, relationships from recent variability have been assumed to be applicable to the preindustrial to present-day change. Our analysis of Aerosol Comparisons between Observations and Models (AeroCom) model simulations suggests that estimates of relationships from recent variability are poor constraints on relationships from anthropogenic change for some terms, with even the sign of some relationships differing in many regions. Proxies connecting recent spatial/temporal variability to anthropogenic change, or sustained measurements in regions where emissions have changed, are needed to constrain estimates of anthropogenic aerosol impacts on cloud radiative forcing. PMID:26921324

  15. Generation of harmonic frequencies and their effects in present day ICRF systems

    NASA Astrophysics Data System (ADS)

    Durodié, F.; Vervier, M.

    1999-09-01

    The whole TEXTOR-94 ICRF system [1,2] circuit has been analyzed, partially modelled and studied at the fundamental operating frequency and, more important, at harmonic frequencies thereof. It has been found that without appropriate measures, present day systems and especially the TEXTOR ICRF system are prone to spurious generation of power at the second harmonic frequency. This leads either to erroneous activation of the reflected power safety protection or to highly increased (in some cases doubled) voltages in the transmission lines and antennas. As the voltage standing waves at the second harmonic displace the total voltage maxima in the transmission lines and antennas, this also explains why arcs are not always found at the expected voltage maxima for the fundamental frequency. The model is also able to give additional explanations why the ASDEX-Upgrade ICRF system has dramatically improved its power handling capabilities after the introduction of the ``3dB coupler reflection compensation scheme'' [3,4]. The output of one of the TEXTOR transmitters has been fitted with a quarter wave length shorted stub which has no effect on the operation at the fundamental frequency but which effectively shorts out the second harmonic. It has to be noted that eg. the Tore Supra RDL [5] antennas are fitted with such a stub in the feeding transmission line whose function is to enter cooling water into the transmission line system. Hence, this could be the explanation of the apparent higher than average power handling capabilities of the TS antenna system. Experimental results clearly indicate a much improved operational power handling capability on plasma and an increased voltage stand-off when conditioning this antenna pair on vacuum. Limits have yet to be explored but already remarkable is the fact that since the installation of the quarter wavelength stub the reflected power safety system has been activated only once and furthermore so in poorly matched conditions.

  16. Statistical dynamical downscaling of present day and future precipitation regimes in southern Vietnam

    NASA Astrophysics Data System (ADS)

    Schubert, David; Reyers, Mark; Pinto, Joaquim; Fink, Andreas; Massmeyer, Klaus

    2016-04-01

    Southeast Asia has been identified as one of the hot-spots of climate change. While the projected changes in annual precipitation are comparatively small, there is a clear tendency towards more rainfall in the dry season and an increase in extreme precipitation events. In this study, a statistical dynamical downscaling (SDD) approach is applied to obtain higher resolution and more robust regional climate change projections for tropical Southeast Asia with focus on Vietnam. First, a recent climate (RC) simulation with the regional climate model COSMO-CLM with a spatial resolution of ~50 km driven by ERA-Interim (1979-2008) is performed for the tropical region of Southeast Asia. For the SDD, six weather types (WTs) are selected for Vietnam during the wet season (April - October) using a k-means cluster analysis of daily zonal wind component in 850 hPa and 200 hPa from the RC run. For each calculated weather type, simulated representatives are selected from the RC run and are then further dynamically downscaled to a resolution of 0.0625° (7 km). By using historical WT frequencies, the simulated representatives are recombined to a high resolution rainfall climatology for the recent climate. It is shown that the SDD is generally able to capture the present day climatology and that the employment of the higher resolved simulated representatives enhances the performance of the SDD. However, an overestimation of rainfall at higher altitudes is found. To obtain future climate projections, an ensemble of eight CMIP5 model members are selected to study precipitation changes. For these projections, WT frequencies of future scenarios under two representative Concentration Pathways (RCP4.5 and RCP8.5) are taken into account for the mid-term scenario (2046-2065) and the long-term scenario (2081-2100). The strongest precipitation changes are found for the RCP8.5 scenario. Most of the models indicate a generally increase in precipitation amount in the wet period over Southeast

  17. Present-day loading rates of faults in the northern Mojave region, California, from GPS Geodesy

    NASA Astrophysics Data System (ADS)

    Spinler, J. C.; Bennett, R. A.; McGill, S. F.

    2013-12-01

    We analyzed GPS data from 45 continuous sites along with 9 campaign sites within the northern Mojave region for the time period 2002.0-2013.0 to model the present-day crustal velocity field for the region. In addition to the 54 sites we analyzed, we included 21 site velocities from the USGS Fort Irwin network and 66 site velocities from the SCEC Crustal Motion Map 4 velocity field. We rotated the USGS and SCEC velocities into our Stable North America Reference Frame (SNARF) through a minimization of the differences amongst sites in common between the different solutions. We used our velocities to constrain an elastic block model in order to estimate fault-loading rates of crustal faults within the northern Mojave region. Each crustal block is allowed to both translate and rotate about a vertical axis. Results include new slip rate estimates for the NW-SE oriented right-lateral strike-slip faults within the eastern California shear zone (ECSZ), including model faults representing the Lenwood-Lockhart fault zone (4.5×0.2 mm/yr), Calico-Blackwater faults (1.0×0.4 mm/yr), and Goldstone Lake fault (1.2×0.5 mm/yr), with a total slip across the ECSZ of ~8-9 mm/yr, lower than some previous geodetic estimates, but slightly higher than geologic estimates. We estimate left-lateral slip rates of 4.4×0.2 and 4.9×0.3 mm/yr for the model faults representing the west-central and central segments of the Garlock fault, respectively, with rates decreasing to 0.5×0.4 mm/yr for the easternmost segment. We estimate clockwise rotation rates of the crustal blocks in the Northeast Mojave domain in the range of 3-5×0.7 °/Myr, consistent with paleomagnetic estimates of as much as 50° since 10 Ma.

  18. Liquid Water Lakes on Mars Under Present-Day Conditions: Sustainability and Effects on the Subsurface

    NASA Astrophysics Data System (ADS)

    Goldspiel, Jules M.

    2015-11-01

    Decades of Mars exploration have produced ample evidence that aqueous environments once existed on the surface. Much evidence supports groundwater emergence as the source of liquid water on Mars [1-4]. However, cases have also been made for rainfall [5] and snow pack melts [6].Whatever the mechanism by which liquid water is emplaced on the surface of Mars, whether from groundwater seeps, atmospheric precipitation, or some combination of sources, this water would have collected in local topographic lows, and at least temporarily, would have created a local surface water system with dynamic thermal and hydrologic properties. Understanding the physical details of such aqueous systems is important for interpreting the past and present surface environments of Mars. It is also important for evaluating potential habitable zones on or near the surface.In conjunction with analysis of surface and core samples, valuable insight into likely past aqueous sites on Mars can be gained through modeling their formation and evolution. Toward that end, we built a 1D numerical model to follow the evolution of small bodies of liquid water on the surface of Mars. In the model, liquid water at different temperatures is supplied to the surface at different rates while the system is subjected to diurnally and seasonally varying environmental conditions. We recently simulated cases of cold (275 K) and warm (350 K) water collecting in a small depression on the floor of a mid southern latitude impact crater. When inflows create an initial pool > 3 m deep and infiltration can be neglected, we find that the interior of the pool can remain liquid over a full Mars year under the present cold and dry climate as an ice cover slowly thickens [7]. Here we present new results for the thermal and hydrologic evolution of surface water and the associated subsurface region for present-day conditions when infiltration of surface water into the subsurface is considered.[1] Pieri (1980) Science 210.[2] Carr

  19. Estimating hypothetical present-day insured losses for past intense hurricanes in the French Antilles

    NASA Astrophysics Data System (ADS)

    Thornton, James; Desarthe, Jérémy; Naulin, Jean-Philippe; Garnier, Emmanuel; Liu, Ye; Moncoulon, David

    2015-04-01

    On the islands of the French Antilles, the period for which systematic meteorological measurements and historic event loss data are available is short relative to the recurrence intervals of very intense, damaging hurricanes. Additionally, the value of property at risk changes through time. As such, the recent past can only provide limited insight into potential losses from extreme storms in coming years. Here we present some research that seeks to overcome, as far as is possible, the limitations of record length in assessing the possible impacts of near-future hurricanes on insured properties. First, using the archives of the French overseas departments (which included administrative and weather reports, inventories of damage to houses, crops and trees, as well as some meteorological observations after 1950) we reconstructed the spatial patterns of hazard intensity associated with three historical events. They are: i) the 1928 Hurricane (Guadeloupe), ii) Hurricane Betsy (1956, Guadeloupe) and iii) Hurricane David (1979, Martinique). These events were selected because all were damaging, and the information available on each is rich. Then, using a recently developed catastrophe model for hurricanes affecting Guadeloupe, Martinique, Saint-Barthélemy and Saint-Martin, we simulated the hypothetical losses to insured properties that the reconstructed events might cause if they were to reoccur today. The model simulated damage due to wind, rainfall-induced flooding and storm surge flooding. These 'what if' scenarios provided an initial indication of the potential present-day exposure of the insurance industry to intense hurricanes. However, we acknowledge that historical events are unlikely to repeat exactly. We therefore extended the study by producing a stochastic event catalogue containing a large number of synthetic but plausible hurricane events. Instrumental data were used as a basis for event generation, but importantly the statistical methods we applied permit

  20. Present-Day 3D Velocity Field of Eastern North America Based on Continuous GPS Observations

    NASA Astrophysics Data System (ADS)

    Goudarzi, Mohammad Ali; Cocard, Marc; Santerre, Rock

    2016-03-01

    The Saint Lawrence River valley in eastern Canada was studied using observations of continuously operating GPS (CGPS) stations. The area is one of the most seismically active regions in eastern North America characterized by many earthquakes, which is also subject to an ongoing glacial isostatic adjustment. We present the current three-dimensional velocity field of eastern North America obtained from more than 14 years (9 years on average) of data at 112 CGPS stations. Bernese GNSS and GITSA software were used for CGPS data processing and position time series analysis, respectively. The results show the counterclockwise rotation of the North American plate in the No-Net-Rotation model with the average of 16.8 ± 0.7 mm/year constrained to ITRF 2008. We also present an ongoing uplift model for the study region based on the present-day CGPS observations. The model shows uplift all over eastern Canada with the maximum rate of 13.7 ± 1.2 mm/year and subsidence to the south mainly over northern USA with a typical rate of -1 to -2 mm/year and the minimum value of -2.7 ± 1.4 mm/year. We compared our model with the rate of radial displacements from the ICE-5G model. Both models agree within 0.02 mm/year at the best stations; however, our model shows a systematic spatial tilt compared to ICE-5G. The misfits between two models amount to the maximum relative subsidence of -6.1 ± 1.1 mm/year to the east and maximum relative uplift of 5.9 ± 2.7 mm/year to the west. The intraplate horizontal velocities are radially outward from the centers of maximum uplift and are inward to the centers of maximum subsidence with the typical velocity of 1-1.6 ± 0.4 mm/year that is in agreement with the ICE-5G model to the first order.

  1. Present-day Tectonic Stress Regimes in Northern Iraq and Surrounding Regions from Focal Mechanism Data

    NASA Astrophysics Data System (ADS)

    Mahdi, H. H.; Abdulnaby, W.; Al-Shukri, H. J.; Numan, N.

    2013-12-01

    The collision zone between the Arabian and the Eurasian plates is one of the most seismically active regions. Northern Iraq represents the northeastern part of the Arabian plate that has a suture zone with the Turkish and Iranian plates named Bitlis-Zagros suture zone. The present-day tectonic stress regimes can be estimated from focal mechanism data. The waveform moment tensor inversion method was used to derive the focal mechanism solution of 65 earthquakes with magnitudes of ≥3.5. Green's functions for the local and regional seismograms were generated in order to perform the moment tensor inversion using complete seismograms. From focal mechanism solutions, the direction of slip and the orientations of the moment tensor axes (P, N, and T) on the fault surface during an earthquake were determined. The tectonic stress regime of each focal mechanism was estimated based on Zoback (1992). The results show that all six categories of the stress regimes, which are normal faulting (NF), normal faulting with strike-slip component (NS), strike-slip faulting (SS), thrust faulting with strike-slip component (TS), thrust faulting (TF), and unknown or oblique faulting (UF), exist. However, the most common tectonic regimes in the study area are the SS (43.94%), UF (27.27%), and TF (13.64%). In most cases, the strike-slip movement on the fault surfaces consists of left-lateral movement. The NF regime, which is located in one small area near Diyala city at the Iraq-Iran border, might be a local tensional stress regime. The directions of the compressional stress axes show that the stress regime at the Zagros suture zone has two directions. One is perpendicular to the suture near the Iraq-Iran border, and the second is parallel to the suture near the Iraq-Turkey border. In addition, the compressional stress axes at the city of Sinjar, near the Iraq-Syria border, have E-W direction. These results are compatible with the tectonic setting of the Arabain-Eurasian continental

  2. A No-Net-Rotation Model of Present-Day Surface Motions

    NASA Astrophysics Data System (ADS)

    Kreemer, C.; Holt, W. E.

    2001-12-01

    A significant portion of the Earth's surface consists of zones of diffuse deformation. The interior regions of these diffuse zones of deformation move at distinctly different velocities from that of adjacent plates, and, because of their complexities, have been ignored in previous no-net-rotation (NNR) models (e.g., NNR-NUVEL1A). We have calculated a new NNR model from a continuous velocity field that incorporates both rigid plate motion and velocity gradients within plate boundary zones. The velocity field is obtained through a bi-cubic Bessel interpolation of almost 3000 geodetic velocities and strain rates inferred from Quaternary faults. The geodetic velocities are taken from about 50 different, mainly published, studies. For each study we have not adopted the original reference frame. Instead, we have solved for a rigid body rotation for each study that rotate the vectors of each study into a model reference frame in the process of satisfying a least-squares fit between model and observed velocities and model and observed strain rates. When compared with earlier NNR models we find significantly different angular velocities for many plates in our model. Differences between the NNR model presented here and earlier NNR models can be attributed to both the effect of including velocity gradients in diffuse plate boundary zones, as well as actual differences between geodetically derived, present-day, surface motions and geologic estimates. We find that for the Indian, Arabian, Nazca, Cocos, Philippine Sea, and the Caribbean plate the differences between our model and the NNR-NUVEL1A model are mainly due to differences between geodetic and geologic plate velocities. For the Eurasian plate the discrepancy that we find between our result and NNR-NUVEL1A model can not only be ascribed to the difference between geodetic and geologic velocities, but also to the significant effect of including plate boundary zones. The significantly different NNR rotation vectors that we

  3. Present-Day 3D Velocity Field of Eastern North America Based on Continuous GPS Observations

    NASA Astrophysics Data System (ADS)

    Goudarzi, Mohammad Ali; Cocard, Marc; Santerre, Rock

    2016-07-01

    The Saint Lawrence River valley in eastern Canada was studied using observations of continuously operating GPS (CGPS) stations. The area is one of the most seismically active regions in eastern North America characterized by many earthquakes, which is also subject to an ongoing glacial isostatic adjustment. We present the current three-dimensional velocity field of eastern North America obtained from more than 14 years (9 years on average) of data at 112 CGPS stations. Bernese GNSS and GITSA software were used for CGPS data processing and position time series analysis, respectively. The results show the counterclockwise rotation of the North American plate in the No-Net-Rotation model with the average of 16.8 ± 0.7 mm/year constrained to ITRF 2008. We also present an ongoing uplift model for the study region based on the present-day CGPS observations. The model shows uplift all over eastern Canada with the maximum rate of 13.7 ± 1.2 mm/year and subsidence to the south mainly over northern USA with a typical rate of -1 to -2 mm/year and the minimum value of -2.7 ± 1.4 mm/year. We compared our model with the rate of radial displacements from the ICE-5G model. Both models agree within 0.02 mm/year at the best stations; however, our model shows a systematic spatial tilt compared to ICE-5G. The misfits between two models amount to the maximum relative subsidence of -6.1 ± 1.1 mm/year to the east and maximum relative uplift of 5.9 ± 2.7 mm/year to the west. The intraplate horizontal velocities are radially outward from the centers of maximum uplift and are inward to the centers of maximum subsidence with the typical velocity of 1-1.6 ± 0.4 mm/year that is in agreement with the ICE-5G model to the first order.

  4. Importance of Past Human and Natural Disturbance in Present-Day Net Ecosystem Productivity

    NASA Astrophysics Data System (ADS)

    Felzer, B. S.; Phelps, P.

    2014-12-01

    Gridded datasets of Net Ecosystem Exchange derived from eddy covariance and remote sensing measurements provide a means of validating Net Ecosystem Productivity (NEP, opposite of NEE) from terrestrial ecosystem models. While most forested regions in the U.S. are observed to be moderate to strong carbon sinks, models not including human or natural disturbances will tend to be more carbon neutral, which is expected of mature ecosystems. We have developed the Terrestrial Ecosystems Model Hydro version (TEM-Hydro) to include both human and natural disturbances to compare against gridded NEP datasets. Human disturbances are based on the Hurtt et al. (2006) land use transition dataset and include transient agricultural (crops and pasture) conversion and abandonment and timber harvest. We include natural disturbances of storms and fires based on stochastic return intervals. Tropical storms and hurricane return intervals are based on Zheng et al. (2009) and occur only along the U.S. Atlantic and Gulf coasts. Fire return intervals are based on LANDFIRE Rapid Assessment Vegetation Models and vegetation types from the Hurtt dataset. We are running three experiments with TEM-Hydro from 1700-2011 for the conterminous U.S.: potential vegetation (POT), human disturbance only (agriculture and timber harvest, LULC), and human plus natural disturbance (agriculture, timber harvest, storms, and fire, DISTURB). The goal is to compare our NEP values to those obtained by FLUXNET-MTE (Jung et al. 2009) from 1982-2008 and ECMOD (Xiao et al., 2008) from 2000-2006 for different plant functional types (PFTs) within the conterminous U.S. Preliminary results show that, for the entire U.S., potential vegetation yields an NEP of 10.8 gCm-2yr-1 vs 128.1 gCm-2yr-1 for LULC and 89.8 gCm-2yr-1 for DISTURB from 1982-2008. The effect of regrowth following agricultural and timber harvest disturbance therefore contributes substantially to the present-day carbon sink, while stochastic storms and fires

  5. Potential autotrophic metabolisms in ultra-basic reducing springs associated with present-day continental serpentinization

    NASA Astrophysics Data System (ADS)

    Morrill, P. L.; Miles, S.; Kohl, L.; Kavanagh, H.; Ziegler, S. E.; Brazelton, W. J.; Schrenk, M. O.

    2013-12-01

    Ultra-basic reducing springs at continental sites of serpentinization act as windows into the biogeochemistry of this subsurface exothermic environment rich in H2 and CH4 gases. Biogeochemical carbon transformations in these systems are of interest because serpentinization creates conditions that are amenable to abiotic and biotic reduction of carbon. However, little is known about the metabolic capabilities of the microorganisms that live in this environment. To determine the potential for autotrophic metabolisms, bicarbonate and CO substrate addition microcosm experiments were performed using water and sediment from an ultra-basic reducing spring in the Tablelands, Newfoundland, Canada, a site of present-day continental serpentinization. CO was consistently observed to be utilized in the Live but not the Killed controlled replicates amended with 10% 13C labelled CO and non-labelled (natural C isotope abundance) CO. In the Live CO microcosms with natural C isotope abundance, the residual CO became enriched in 13C (~10 ‰) consistent with a decrease in the fraction of CO remaining. In the Killed CO controlled replicates with natural C isotope abundance the CO showed little 13C enrichment (~1.3 ‰). The data from the Live CO microcosms were well described by a Rayleigh isotopic distillation model, yielding an isotopic enrichment factor for microbial CO uptake of 15.7 ×0.5 ‰ n=2. These data suggest that there was microbial CO utilization in these experiments. The sediment and water from the 13C-labelled and non-labelled, Live and Killed microcosms were extracted for phospholipid fatty acids (PLFAs) to determine changes in community composition between treatments as well as to determine the microbial uptake of CO. The difference in community composition between the Live and Killed microcosms was not readily resolvable based on PLFA distributions. Additionally, the microbial uptake of 13CO had minimal to no affect on the δ13C of the cellular biomarkers, with the

  6. Influence of ocean tide dynamics on the climate system from the Cretaceous to present day

    NASA Astrophysics Data System (ADS)

    Weber, Tobias; Thomas, Maik

    2016-04-01

    Global numerical ocean models used for paleo-climate reconstructions generally only consider the ocean's general circulation, but neglect tidal dynamics. However, it has been demonstrated that tidally induced friction at the ocean bottom alters the mean ocean circulation and energy fluxes on timescales larger than one tidal period and up to climate timescales. Thereby the mean ocean circulation and temperature advection is altered and can thus affect climate. We simultaneously modeled the ocean's general circulation and tidal dynamics for five time-slices from the Cretaceous to present day: the Albian (ca. 110 million years ago, Ma), the Cenomanian-Turonian Boundary (ca. 93 Ma, CTB), the early Eocene (ca. 55 Ma), the early Pliocene (ca. 3.5 Ma), and a pre-industrial period (ca. 1850 AD). These simulations show that the tectonic evolution of ocean basins changes the resonance conditions in the paleo-oceans over time and thus the position of amphydromic systems and the amplitudes of partial tides. Largest amplitudes of the M2 partial tide are obtained during the early Eocene when they are in the global mean by 150% larger than in the CTB, when amplitudes are smallest. The evolution of the tidal system leads to an individual interaction between tidal dynamics and the ocean general circulation for all time-slices. In the Albian a reduction of horizontal velocities of up to 50% is simulated in the deep Indo-Pacific Throughflow (IPT) below 1000m depth. This reduction is the product of tidal residual mean currents induced by tidal waves propagating from the Pacific Ocean into the Indian Ocean that oppose the prevailing eastward thermohaline currents. In all other time-slices mainly an increase in horizontal transports is simulated. In the CTB both tidal residual mean currents (less than 0.2cm/s in most of the ocean) and the general ocean circulation (less than 0.5cm/s) are small, thus leading to a tidally induced increase by 50% in horizontal velocities in almost half of

  7. Present-Day Seasonal Gully Activity in a South Polar Pit (Sisyphi Cavi) on Mars

    NASA Astrophysics Data System (ADS)

    Raack, Jan; Reiss, Dennis; Appéré, Thomas; Vincendon, Mathieu; Ruesch, Ottaviano; Hiesinger, Harald

    2014-05-01

    Seasonal activity of gullies under current climatic conditions on Mars was observed by [1-7]. Dundas et al. [2] reviewed the present-day activity of classical gullies (including the gully presented in this work), dune gullies, and other mass wasting processes in the southern hemisphere on Mars. Recent polar gullies in Sisyphi Cavi were also analyzed by [8], who estimated ages of about 20 ka to 20 Ma for the gullies. In this study we focus on a single gully in Sisyphi Cavi, located in the south polar region at 1.44° E and 68.54° S. The gully occurs on the gullied equator-facing slope of an isolated polar pit within an infilled impact crater. Multi-temporal high-resolution image data analyses show new deposits at the terminus of the gully channel and on the gully apron within spring (after solar longitudes of 236°) of martian years (MY) 29 and 31. In MY 29 deposition of material shortens the channel by about 40 m; in MY 31 a new deposit at the western flank of the gully apron with approximately 300-600 m3 of material is visible [3]. Our morphological investigations show that the identified new deposits were formed by dark flows through the entire gully deposited on top of the apron between LS ~218° and ~226°. Thermal data show a temperature increase between solar longitudes (LS) ~218° and ~226°. Near-infrared spectral data show relatively constant band strengths of CO2 ice and H2O ice in this time range. After the formation of the dark flows (after LS ~226°), temperatures increase rapidly from ~180 K to >~270 K at LS ~250°. At this time, spectral data indicate that all volatiles on the surface sublimated. However, an earlier beginning of sublimation when the dark flows were observed (between LS ~218° and ~226°) is likely, due to the fact that the instruments can only show the last phase of sublimation (decrease of volatile band strengths) [3]. Spectral modeling shows that from winter to mid-spring, the surface of the studied area is covered by CO2 slab

  8. Sedimentary Mounds on Mars: Tracing Present-day Formation Processes into the Past

    NASA Technical Reports Server (NTRS)

    Niles, P. B.; Michalski, J.; Edwards, C. S.

    2014-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one and revealed spectacular views of finely layered sedimentary materials throughout the globe [1]. Some of these sedimentary deposits are 'mound' shaped and lie inside of craters (Fig 1). Crater mound deposits are found throughout the equatorial region, as well as ice-rich deposits found in craters in the north and south polar region [2-4]. Despite their wide geographical extent and varying volatile content, the 'mound' deposits have a large number of geomorphic and structural similarities that suggest they formed via equivalent processes. Thus, modern depositional processes of ice and dust can serve as an invaluable analog for interpreting the genesis of ancient sedimentary mound deposits.

  9. Present-Day Vegetation Helps Quantifying Past Land Cover in Selected Regions of the Czech Republic

    PubMed Central

    Abraham, Vojtěch; Oušková, Veronika; Kuneš, Petr

    2014-01-01

    The REVEALS model is a tool for recalculating pollen data into vegetation abundances on a regional scale. We explored the general effect of selected parameters by performing simulations and ascertained the best model setting for the Czech Republic using the shallowest samples from 120 fossil sites and data on actual regional vegetation (60 km radius). Vegetation proportions of 17 taxa were obtained by combining the CORINE Land Cover map with forest inventories, agricultural statistics and habitat mapping data. Our simulation shows that changing the site radius for all taxa substantially affects REVEALS estimates of taxa with heavy or light pollen grains. Decreasing the site radius has a similar effect as increasing the wind speed parameter. However, adjusting the site radius to 1 m for local taxa only (even taxa with light pollen) yields lower, more correct estimates despite their high pollen signal. Increasing the background radius does not affect the estimates significantly. Our comparison of estimates with actual vegetation in seven regions shows that the most accurate relative pollen productivity estimates (PPEs) come from Central Europe and Southern Sweden. The initial simulation and pollen data yielded unrealistic estimates for Abies under the default setting of the wind speed parameter (3 m/s). We therefore propose the setting of 4 m/s, which corresponds to the spring average in most regions of the Czech Republic studied. Ad hoc adjustment of PPEs with this setting improves the match 3–4-fold. We consider these values (apart from four exceptions) to be appropriate, because they are within the ranges of standard errors, so they are related to original PPEs. Setting a 1 m radius for local taxa (Alnus, Salix, Poaceae) significantly improves the match between estimates and actual vegetation. However, further adjustments to PPEs exceed the ranges of original values, so their relevance is uncertain. PMID:24936973

  10. Present-day vegetation helps quantifying past land cover in selected regions of the Czech Republic.

    PubMed

    Abraham, Vojtěch; Oušková, Veronika; Kuneš, Petr

    2014-01-01

    The REVEALS model is a tool for recalculating pollen data into vegetation abundances on a regional scale. We explored the general effect of selected parameters by performing simulations and ascertained the best model setting for the Czech Republic using the shallowest samples from 120 fossil sites and data on actual regional vegetation (60 km radius). Vegetation proportions of 17 taxa were obtained by combining the CORINE Land Cover map with forest inventories, agricultural statistics and habitat mapping data. Our simulation shows that changing the site radius for all taxa substantially affects REVEALS estimates of taxa with heavy or light pollen grains. Decreasing the site radius has a similar effect as increasing the wind speed parameter. However, adjusting the site radius to 1 m for local taxa only (even taxa with light pollen) yields lower, more correct estimates despite their high pollen signal. Increasing the background radius does not affect the estimates significantly. Our comparison of estimates with actual vegetation in seven regions shows that the most accurate relative pollen productivity estimates (PPEs) come from Central Europe and Southern Sweden. The initial simulation and pollen data yielded unrealistic estimates for Abies under the default setting of the wind speed parameter (3 m/s). We therefore propose the setting of 4 m/s, which corresponds to the spring average in most regions of the Czech Republic studied. Ad hoc adjustment of PPEs with this setting improves the match 3-4-fold. We consider these values (apart from four exceptions) to be appropriate, because they are within the ranges of standard errors, so they are related to original PPEs. Setting a 1 m radius for local taxa (Alnus, Salix, Poaceae) significantly improves the match between estimates and actual vegetation. However, further adjustments to PPEs exceed the ranges of original values, so their relevance is uncertain. PMID:24936973

  11. Late Holocene and present-day fluvial morphodynamics in small catchment areas of Central Germany

    NASA Astrophysics Data System (ADS)

    Englhard, Michael; Damm, Bodo; Frechen, Manfred; Terhorst, Birgit

    2010-05-01

    During the past decades strong runoff events repeatedly occurred in small drainage basins of the European low mountains. In numerous events runoff was connected with erosion and transport of extensive bed load. Runoff events were predominantly triggered by rainstorms, which were limited to the catchment areas. They partly caused severe economic loss. The present study focuses on fluvial morphodynamics in northern Hesse and Lower Saxony. In this area runoff and transport of bed load occurred in small tributary catchment areas of the Fulda, Werra and Oberweser rivers. In general, the small drainage basins are used by agriculture and forestry. Drainage channels are developed as gullies and are incised into solid bedrock, Quaternary hillslope sediments, alluvial fills, and anthropogenic deposits. Vertical incision into the bedrock may amount to 1 meter per event. Furthermore, in single cases sediment discharge amounted to 16.000 m³ in addition to the suspension load. On the base of historical analyses about 50 severe runoff events with a maximum frequency of 10 events during 1965 are recorded during the past 150 years in the study area. Field survey, sedimentological analyses and dating reveal intensive runoff processes since the Neolithic age in a comparable catchment area. In this context potsherds could be dated to the Linear Pottery culture, which were detected in an alluvial cone of the "Rehgraben gully", close to the city of.Kassel. Furthermore, findings of fossil wood were recovered in the same alluvial cone. Radiocarbon dating reveals calibrated ages which are for the most parts younger than AD. In younger sediments we suppose the severe runoff event of 1342. Current studies in the catchment area of the Rehgraben aim to distinguish different processes of the fluvial morphodynamics on a temporal scale and to estimate potential Holocene erosional rates. References Damm, B., 2004. Geschiebe führende und murfähige Wildbäche in Mittelgebirgsr

  12. Present-day crustal motion along the Longitudinal Valley Fault, eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Yu, Shui-Beih; Kuo, Long-Chen

    2001-04-01

    The NNE-striking Longitudinal Valley Fault (LVF) in eastern Taiwan is an extremely active high-angle thrust fault. It bounds the Coastal Range and the Longitudinal Valley, which is considered a collision boundary between the Philippine Sea and the Eurasian plates. Repeated GPS data in the Longitudinal Valley area from 1992 to 1999 are utilized to study the spatial variation of crustal motion along the LVF. With respect to Penghu in the Chinese continental margin, velocities for stations on the western side of the LVF (Longitudinal Valley and eastern Central Range) are 18-35 mm/yr in directions 283-311°, whereas those on the eastern side of the LVF, the Coastal Range, are 28-68 mm/yr in directions 303-324°. A major discontinuity of about 30 mm/yr on the rate of crustal motion across the Longitudinal Valley is attributed to the aseismic slip along the LVF as revealed by trilateration data previously. To the south of Fengping, the block motions of the Coastal Range are 31-40 mm/yr in 317-330° relative to the Central Range, while the near-fault motions are 13-33 mm/yr in 309-336°. Various partitions on the left-lateral strike-slip and convergent components along the LVF are found. In the southern Longitudinal Valley crustal motion is mainly accommodated on the LVF and the Luyeh Fault. In contrast, those in the central and northern Longitudinal Valley are partly taken up on the faults to the east of the LVF or result in the elastic deformation of the Coastal Range. The crustal motion in the northern Longitudinal Valley area is likely to be distributed in the several NE-striking thrusts in a horsetail pattern and obliquely cut the northern Coastal Range, with a small portion of fault-slips along the LVF. Data from dense-deployed GPS networks across the LVF can be employed to give better estimates of near-fault motions and delineate the surface traces of the LVF. Repeated GPS and leveling data from two stations on both ends of the Yuli Bridge that are 575 m apart

  13. Lyman Alpha-emitting Galaxies at z = 2.1: Characterizing the Progenitors of Typical Present-day Galaxies

    NASA Astrophysics Data System (ADS)

    Gawiser, Eric J.; Guaita, L.; Padilla, N.; Francke, H.; Bond, N. A.; Gronwall, C.; Ciardullo, R.; Sinawa, S.; Feldmeier, J. J.; MUSYC Collaboration

    2010-01-01

    We discovered a sample of 261 Lyman alpha emitting (LAE) galaxies at z=2.1 in an ultra-deep 3727A narrow-band MUSYC image of the Extended Chandra Deep Field-South. LAEs were selected to have rest-frame equivalent widths >20A and emission line fluxes >3.7x10-17 ergs/cm2/s, corresponding to L_Lya>1.2x1042 ergs/s. 3% of the original candidates were detected in X-rays by Chandra, and 7% were detected in the rest-frame far-UV by GALEX; these objects were eliminated to minimize contamination by AGN and low-redshift galaxies. Our sample has median rest-frame EW=40A, and only a few galaxies have rest-frame EW bigger than 200A. Our results show that the luminosity function of LAEs at z=2.1 is consistent with that of LAEs at z=3.1 but with number density a factor of 1.8+-0.3 higher. We used the rest frame UV luminosity to estimate a median star formation rate of 4 Msun/yr. Clustering analysis reveals that LAEs at z=2.1 have r0=3+-0.5 Mpc, corresponding to b=1.0+-0.2, the lowest clustering bias of any high-redshift galaxy population. This implies that z=2.1 LAEs reside in dark matter halos with masses 1010 Msun, which are the lowest-mass halos yet probed at this redshift. We used the Sheth-Tormen conditional mass function to study the descendants of these LAEs and found that their typical present-day descendants are local galaxies with sub-L* and L* luminosities, like the Milky Way. We gratefully acknowledge grant support for this research from NSF, DOE, and NASA.

  14. Present-day crustal deformation along the Magallanes-Fagnano Fault System in Tierra del Fuego from repeated GPS observations

    NASA Astrophysics Data System (ADS)

    Mendoza, L.; Perdomo, R.; Hormaechea, J. L.; Del Cogliano, D.; Fritsche, M.; Richter, A.; Dietrich, R.

    2011-03-01

    The present-day deformation of the earth crust in the Argentine part of Tierra del Fuego main island (southernmost South America) is here investigated based on repeated geodetic GPS observations. The island is traversed by the active transform boundary between the South American and Scotia tectonic plates, represented by the Magallanes-Fagnano fault system. Since 1993 a regional network comprising to date 29 GPS sites has been observed almost every year. The complete set of accumulated observations was processed using the Bernese GPS software and state-of-the-art processing strategies and models. The utilization of homogeneous GPS products resulting from a reprocessing of the global IGS network warrants a stable realization of a global reference frame. For each GPS site 3-D positions and linear velocities with error estimates were obtained. A strain analysis of the horizontal velocity components revealed the zones of major deformation activity. A 30-km-wide deformation belt centred on the main trace of the fault system was identified. This belt is bordered to the north (South America) and south (Scotia) by geodynamically stable zones, which move horizontally with a relative average velocity of 4.4 ± 0.6 (east) and -0.3 ± 0.4 (north) mm a-1. Within the deformation belt a maximum strain rate in the order of 0.25 μstrain per year has been detected. A pronounced change in the deformation style from transtension (east) to transpression (west) is observed. The area of predominating shortening of the crust coincides with a local rotation minimum and relative uplift. Throughout the period covered by the GPS observations the displacements and deformations occurred to be linear with time.

  15. Mantle-circulation models with sequential data assimilation: inferring present-day mantle structure from plate-motion histories.

    PubMed

    Bunge, Hans-Peter; Richards, M A; Baumgardner, J R

    2002-11-15

    limited in age to the Cretaceous. This result implies that sequential assimilation of past plate-motion models is ineffective in studying the temporal evolution of core-mantle-boundary heterogeneity, and that a method for extrapolating present-day information backwards in time is required. For short time periods (of the order of perhaps a few tens of Myr) such a method exists in the form of crude 'backward' convection calculations. For longer time periods (of the order of a mantle overturn), a rigorous approach to extrapolating information back in time exists in the form of iterative nonlinear optimization methods that carry assimilated information into the past through the use of an adjoint mantle convection model. PMID:12460480

  16. Evolution of the stress field in the southern Scotia Arc from the late Mesozoic to the present-day

    NASA Astrophysics Data System (ADS)

    Maestro, Adolfo; López-Martínez, Jerónimo; Galindo-Zaldívar, Jesús; Bohoyo, Fernando; Mink, Sandra

    2014-12-01

    The geological evolution of the Scotia Arc, which developed between Antarctica and South America, has facilitated the connection between the Pacific and Atlantic oceans and, has important global implications. To improve the knowledge of the late Mesozoic evolution of the southern Scotia Arc, over 6000 brittle mesostructures were measured over the last 20 years at different outcrops from the northern Antarctic Peninsula and the South Shetland Islands as well as the James Ross and South Orkney archipelagos. This dataset covers a length of more than 1000 km of the arc. Fault data were analysed using the Etchecopar, y-R, Right Dihedra, Stress Inversion and Search Grid Inversion Palaeostress Determination methods. A total of 275 stress tensors were obtained. The results showed that the maximum horizontal stress was in the ENE-WSW and the NW-SE orientations and that the horizontal extension tensors were oriented NE-SW and NW-SE. In addition, seismic activity and focal mechanism solutions were analysed using the Gephart method to establish the present-day stress field and characterise the active tectonics. The results obtained suggest that there is a regional NE-SW compression and a NW-SE extension regime at the present day. The Southern Scotia Arc has a complex geological history due to the different tectonic settings (transform, convergent and divergent) that have affected this sector during its geological evolution from the late Mesozoic until the present day. Six stress fields were obtained from the brittle mesostructure population analysis in the region. The NW-SE and N-S maximum horizontal stresses were related to a combination of Mesozoic oceanic subduction of the former Phoenix Plate under the Pacific margin of the Antarctic Plate, Mesozoic-Cenozoic subduction of the northern Weddell Sea and the Oligocene to the Middle Miocene dextral strike-slip movement between the Scotia and Antarctic plates along the South Scotia Ridge. The NE-SW compression was related to

  17. Past agricultural land use and present-day fire regimes can interact to determine the nature of seed predation.

    PubMed

    Stuhler, John D; Orrock, John L

    2016-06-01

    Historical agriculture and present-day fire regimes can have significant effects on contemporary ecosystems. Although past agricultural land use can lead to long-term changes in plant communities, it remains unclear whether these persistent land-use legacies alter plant-consumer interactions, such as seed predation, and whether contemporary disturbance (e.g., fire) alters the effects of historical agriculture on these interactions. We conducted a study at 27 sites distributed across 80,300 ha in post-agricultural and non-agricultural longleaf pine woodlands with different degrees of fire frequency to test the hypothesis that past and present-day disturbances that alter plant communities can subsequently alter seed predation. We quantified seed removal by arthropods and rodents for Tephrosia virginiana and Vernonia angustifolia, species of conservation interest. We found that the effects of land-use history and fire frequency on seed removal were contingent on granivore guild and microhabitat characteristics. Tephrosia virginiana removal was greater in low fire frequency sites, due to greater seed removal by rodents. Although overall removal of V. angustifolia did not differ among habitats, rodents removed more seeds than arthropods at post-agricultural sites and non-agricultural sites with low fire frequencies, but not at non-agricultural sites with high fire frequencies. Land-use history and fire frequency also affected the relationship between microhabitat characteristics and removal of V. angustifolia. Our results suggest that historical agriculture and present-day fire regimes may alter seed predation by shifting the impact of rodent and arthropod seed predators among habitats, with potential consequences for the establishment of rare plant species consumed by one or both predators. PMID:26905418

  18. Very high resolution modelling of the Surface Mass Balance of the Greenland Ice Sheet: Present day conditions and future prospects.

    NASA Astrophysics Data System (ADS)

    Mottram, Ruth; Aðalgeirsdóttir, Guðfinna; Boberg, Fredrik; Hesselbjerg Christensen, Jens; Bøssing Christensen, Ole; Langen, Peter; Rodehacke, Christian; Stendel, Martin; Yang, Shuting

    2014-05-01

    Recent experiments with the Regional Climate Model (RCM) HIRHAM5 have produced new surface mass balance (SMB) estimates at the unprecedented high horizontal resolution of 0.05 degrees (~5.5km). These simulations indicate a present day SMB of 347 ± 98 Gt/year over the whole ice sheet averaged over the period 1989 - 2012 driven by the ERA-Interim reanalysis dataset. We validate accumulation rates over the ice sheet using estimates from shallow firn cores to confirm the importance of resolution to accurate estimates of accumulation. Comparison with PROMICE and GC-Net automatic weather station observations shows the model represents present day climate and climate variability well when driven by the ERA-Interim reanalysis dataset. Comparison with a simulation at 0.25 degrees (~27km) resolution from the same model shows a significantly different calculated SMB over the whole ice sheet, largely due to changes in precipitation distribution over Greenland. The very high resolution requires a more sophisticated treatment of sub-grid scale processes in the snow pack including meltwater retention and refreezing and an enhanced albedo scheme. Our results indicate retention processes account for a significant proportion of the total surface budget based on a new parameterization scheme in the model. SMB projections, driven by the EC-Earth Global Climate Model (GCM) at the boundaries for the RCP 4.5 scenario indicate a declining surface mass balance over the 21st century with some compensation for warmer summer temperatures and enhanced melt in the form of increased precipitation. A cold bias in the driving GCM for present day conditions suggests that this simulation likely underestimates the change in SMB. However, the downscaled precipitation fields compare well with those in the reanalysis driven simulations. A soon-to-be complete simulation uses driving fields from the GCM running the RCP8.5 scenario.

  19. The present-day strain partitioning of the Western Alps and its relationships with the crustal scale geometry

    NASA Astrophysics Data System (ADS)

    Schwartz, S.; Lardeaux, J. M.; Tricart, P.; Paul, A.; Béthoux, N.; Masson, F.

    2003-04-01

    In the orogenic belt, the combination of the geological data (tectonic, petrologic and kinematic analysis) with the geophysical imagery of the crust (regional seismicity, local earthquake tomography and gravimetry) allows to obtain crustal scale models coherent with the present-day deformation. In this way, the recent pluridisciplinary studies performed in the framework of " Geo-France 3D Alpes " show an important syn-convergence strain-partitioning at the scale of the western alpine belt. In the internal domain, this strain-partitioning, corresponds to extensional tectonics combinated with important strike-slip components while the external domain and the Po plain, located at the periphery, record an important shortening accomodated in surface by thrust and strike-slip faults. In order to understand the alpine present-day strain pattern, we propose and discuss a new crustal-scale cross-section performed along the Pelvoux-Dora Maira transect. The proeminent features of this crustal-scale geometry are : -the existence of a slice of cold and rigid mantle of Apulian origin beneath the Dora Maira massif. This rigid mantle is truncated in two distinct bodies by a system of deeply-rooted vertical faults related to the Insubric line. -these two main bodies of mantle acted as indenters driving the decoupling of the European crust and at least a part of the exhumation of the high-pressure metamorphic units. -the deep architecture is characterized by the stacking of crustal slices detached from the European lithosphere. Some of these slices represent tectonic extrusions within the overlying Piemont Schistes lustrés. -the Monviso eclogitized ophiolites are plunging up to 20 km depth below the Piemont schistes lustrés. In this geometrical model, the decoupling of the mantle identor drives the crustal-scale strain-partitioning of the western Alps. Indeed, the lower part of the rigid mantle transfers the compression onto the european foreland and is responsible for the present-day

  20. Present-day and future Antarctic ice sheet climate and surface mass balance in the Community Earth System Model

    NASA Astrophysics Data System (ADS)

    Lenaerts, Jan T. M.; Vizcaino, Miren; Fyke, Jeremy; van Kampenhout, Leo; van den Broeke, Michiel R.

    2016-02-01

    We present climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS) as simulated by the global, coupled ocean-atmosphere-land Community Earth System Model (CESM) with a horizontal resolution of ˜1° in the past, present and future (1850-2100). CESM correctly simulates present-day Antarctic sea ice extent, large-scale atmospheric circulation and near-surface climate, but fails to simulate the recent expansion of Antarctic sea ice. The present-day Antarctic ice sheet SMB equals 2280 ± 131 {Gt year^{-1}} , which concurs with existing independent estimates of AIS SMB. When forced by two CMIP5 climate change scenarios (high mitigation scenario RCP2.6 and high-emission scenario RCP8.5), CESM projects an increase of Antarctic ice sheet SMB of about 70 {Gt year^{-1}} per degree warming. This increase is driven by enhanced snowfall, which is partially counteracted by more surface melt and runoff along the ice sheet's edges. This intensifying hydrological cycle is predominantly driven by atmospheric warming, which increases (1) the moisture-carrying capacity of the atmosphere, (2) oceanic source region evaporation, and (3) summer AIS cloud liquid water content.

  1. Iceland hotspot track in southeast Greenland causes huge present-day vertical viscoelastic motion of the bedrock

    NASA Astrophysics Data System (ADS)

    Khan, Shfaqat Abbas; Sasgen, Ingo; Bevis, Michael; van Dam, Tonie; Wahr, John; Bamber, Jonathan; Wouters, Bert; Helm, Veit; Willis, Michael; Csatho, Beata; Knudsen, Per; Kuipers Munneke, Peter; Kjær, Kurt

    2016-04-01

    The process of Glacial Isostatic Adjustment (GIA) represents the ongoing response of the solid Earth to past ice mass loss that occurred following the Last Glacial Maximum (LGM, ~21 ka B.P.). The magnitude of the GIA uplift depends on the temporal history of the ice load and is highly sensitive to variations in upper mantle viscosity. Greenland GIA is thought to be well contained and due to relative high viscosity, influence of more recent changes e.g. since the Little Ice Age have minor present-day effect (<2 mm/yr). Here we use data from the Greenland Global Positioning System (GPS) network to measure GIA. We identify an unexpected GIA anomaly of ~12 mm/yr in southeast Greenland, which we interpret as linked to a zone of warmer upper mantle caused by the Iceland hotspot track that would reduce the viscosity and produce greater viscoelastic uplift due to recent ice mass changes. We reconsider the evolution of the Greenland ice sheet since LGM and estimate a total ice mass loss equivalent to sea level rise of 4.9 m since LGM. Our observations suggest southeast and northwest Greenland, subject to present-day major ice loss, also contributed by significantly more mass loss on millennia scale than previously estimated.

  2. Isolation and prominent aboriginal maternal legacy in the present-day population of La Gomera (Canary Islands).

    PubMed

    Fregel, Rosa; Cabrera, Vicente M; Larruga, José M; Hernández, Juan C; Gámez, Alejandro; Pestano, Jose J; Arnay, Matilde; González, Ana M

    2015-09-01

    The present-day population structure of La Gomera is outstanding in its high aboriginal heritage, the greatest in the Canary Islands. This was earlier confirmed by both mitochondrial DNA and autosomal analyses, although genetic drift due to the fifteenth century European colonization could not be excluded as the main factor responsible. The present mtDNA study of aboriginal remains and extant samples from the six municipal districts of the island indeed demonstrates that the pre-Hispanic colonization of La Gomera by North African people involved a strong founder event, shown by the high frequency of the indigenous Canarian U6b1a lineage in the aboriginal samples (65%). This value is even greater than that observed in the extant population (44%), which in turn is the highest of all the seven Canary Islands. In contrast to previous results obtained for the aboriginal populations of Tenerife and La Palma, haplogroups related to secondary waves of migration were not detected in La Gomera aborigines, indicating that isolation also had an important role in shaping the current population. The rugged relief of La Gomera divided into several distinct valleys probably promoted subsequent aboriginal intra-insular differentiation that has continued after the European colonization, as seen in the present-day population structure observed on the island. PMID:25407001

  3. Isolation and prominent aboriginal maternal legacy in the present-day population of La Gomera (Canary Islands)

    PubMed Central

    Fregel, Rosa; Cabrera, Vicente M; Larruga, José M; Hernández, Juan C; Gámez, Alejandro; Pestano, Jose J; Arnay, Matilde; González, Ana M

    2015-01-01

    The present-day population structure of La Gomera is outstanding in its high aboriginal heritage, the greatest in the Canary Islands. This was earlier confirmed by both mitochondrial DNA and autosomal analyses, although genetic drift due to the fifteenth century European colonization could not be excluded as the main factor responsible. The present mtDNA study of aboriginal remains and extant samples from the six municipal districts of the island indeed demonstrates that the pre-Hispanic colonization of La Gomera by North African people involved a strong founder event, shown by the high frequency of the indigenous Canarian U6b1a lineage in the aboriginal samples (65%). This value is even greater than that observed in the extant population (44%), which in turn is the highest of all the seven Canary Islands. In contrast to previous results obtained for the aboriginal populations of Tenerife and La Palma, haplogroups related to secondary waves of migration were not detected in La Gomera aborigines, indicating that isolation also had an important role in shaping the current population. The rugged relief of La Gomera divided into several distinct valleys probably promoted subsequent aboriginal intra-insular differentiation that has continued after the European colonization, as seen in the present-day population structure observed on the island. PMID:25407001

  4. Unraveling the geochemistry of melts in exhumed mantle domains in present-day and fossil magma-poor rifted margins

    NASA Astrophysics Data System (ADS)

    Amann, Méderic; Ulrich, Marc; Autin, Julia; Manatschal, Gianreto; Epin, Marie-Eva; Müntener, Othmar; Boiron, Marie-Christine; Sauter, Daniel

    2016-04-01

    The role of magmatic processes occurring during the continental break-up and the onset of steady-state seafloor spreading are still a matter of debate. Beside the tectonic processes like stretching, thinning and exhumation, magmatic processes also play a key role in the evolution and breakup of magma-poor rifted margins. To unravel the impact of such processes, Ocean-Continent-Transitions (OCTs) are of particular interest. OCTs are complex areas where hyper-extended continental crust, exhumed mantle and proto-oceanic crust occur. All these domains have been identified and sampled in both present-day (Iberia/Newfoundland margins) and fossil margins (Platta/Err nappes). In this study, we present preliminary results that enable to characterize the nature of the mantle rocks and the melts found in the OCTs of these paleo- and present-day margins with the aim to investigate how the mantle evolves from initial exhumation to final lithospheric breaks. In OCTs two types of mantle rocks can be observed: (i) a « sub-continental type » free of syn-exhumation melt imprint preserving the early geochemical evolution, and (ii) a « refertilized type » characterized by melt infiltration and mantle-melt interaction. Melts from these domains have different major, trace element and isotopic compositions and can therefore be used to constrain how melt interacts with the mantle and to understand the role of magmatic processes in the break-up. We therefore summarized whole-rock, in-situ and isotopic analysis available in the literature from the Iberia/Newfoundland present-day margin system and completed the existing database with new additional data from the Iberia margin. These new data have been obtained using in-situ technics mainly on clinopyroxenites, serpentinized peridotites and gabbros of ODP drill cores. Around 200 new data have been acquired using the LA-ICPMS technic. Preliminary results show that clinopyroxenes in serpentinized peridodite breccia from ODP site 637A and

  5. Simple models for late Holocene and present-day Patagonian glacier fluctuations and predictions of a geodetically detectable isostatic response

    NASA Astrophysics Data System (ADS)

    Ivins, Erik R.; James, Thomas S.

    1999-09-01

    The late Holocene glacial moraine chronology in the southernmost South American Andes includes four ^1 ^4 C dated Neoglacial advances and retreats. These are used as proxy information to characterize mass fluctuation of the Patagonian icefields during the last 5000 years. Modelled ice loads force a phase-lagged viscoelastic gravitational deformation of the solid Earth. The ancient glacier fluctuations may, therefore, drive present-day crustal motion even in the absence of present-day ice mass imbalance. Numerical models show that such rates of present-day uplift and subsidence are larger than those driven by the viscous memory of late Pleistocene deglaciation. Both spherical and flat-earth models are employed, the latter being used to study exhaustively the effects of glacial load history on the predicted vertical crustal velocity. Recent assessment of net mass balance from 1944 to 1985 indicates that the Southern Patagonian icefield has significantly deteriorated due to snout retreat and thinning. Volume loss rates are estimated at about 3.4-9.3 km^3 yr^- ^1 . The predicted vertical isostatic response to this recession and to the modelled Holocene Neoglaciations is at a marginally detectable level (~1 mm yr^- ^1 ) if the mantle/asthenosphere beneath Patagonia has a viscosity of about 10^2 ^1 Pa s. However, for reduced mantle viscosities, the younger Holocene glacial load histories predict larger signatures. In fact, if the viscosity is about 2x10^2 ^0 Pa s, or lower, then geodetically detectable vertical motion may be driven by a regional Little Ice Age (LIA) (1400-1750 AD) glacier advance and subsequent 20th century retreat. Although this value for mantle viscosity is lower than thought typical of continental shield mantle (~10^2 ^1 Pa s), it is consistent with inversions for post-seismic relaxation time constants in island arc environments and in regions with significant Neogene continental tectonism. In the viscosity regime of 5x10^1 ^8 -2x10^1 ^9 Pa s, the

  6. Oxidation of dissolved iron under warmer, wetter conditions on Mars: Transitions to present-day arid environments

    NASA Technical Reports Server (NTRS)

    Burns, R. G.

    1993-01-01

    The copious deposits of ferric-iron assemblages littering the surface of bright regions of Mars indicate that efficient oxidative weathering reactions have taken place during the evolution of the planet. Because the kinetics of atmosphere-surface (gas-solid) reactions are considerably slower than chemical weathering reactions involving an aqueous medium, most of the oxidation products now present in the martian regolith probably formed when groundwater flowed near the surface. This paper examines how chemical weathering reactions were effected by climatic variations when warm, wet environments became arid on Mars. Analogies are drawn with hydrogeochemical and weathering environments on the Australian continent where present-day oxidation of iron is occurring in acidic ground water under arid conditions.

  7. HLA Class I and Class II Alleles and Haplotypes Confirm the Berber Origin of the Present Day Tunisian Population

    PubMed Central

    Hajjej, Abdelhafidh; Almawi, Wassim Y.; Hattab, Lasmar; El-Gaaied, Amel; Hmida, Slama

    2015-01-01

    In view of its distinct geographical location and relatively small area, Tunisia witnessed the presence of many civilizations and ethnic groups throughout history, thereby questioning the origin of present-day Tunisian population. We investigated HLA class I and class II gene profiles in Tunisians, and compared this profile with those of Mediterranean and Sub-Sahara African populations. A total of 376 unrelated Tunisian individuals of both genders were genotyped for HLA class I (A, B) and class II (DRB1, DQB1), using reverse dot-blot hybridization (PCR-SSO) method. Statistical analysis was performed using Arlequin software. Phylogenetic trees were constructed by DISPAN software, and correspondence analysis was carried out by VISTA software. One hundred fifty-three HLA alleles were identified in the studied sample, which comprised 41, 50, 40 and 22 alleles at HLA-A,-B,-DRB1 and -DQB1 loci, respectively. The most frequent alleles were HLA-A*02:01 (16.76%), HLA-B*44:02/03 (17.82%), HLA-DRB1*07:01 (19.02%), and HLA-DQB1*03:01 (17.95%). Four-locus haplotype analysis identified HLA-A*02:01-B*50:01-DRB1*07:01-DQB1*02:02 (2.2%) as the common haplotype in Tunisians. Compared to other nearby populations, Tunisians appear to be genetically related to Western Mediterranean population, in particular North Africans and Berbers. In conclusion, HLA genotype results indicate that Tunisians are related to present-day North Africans, Berbers and to Iberians, but not to Eastern Arabs (Palestinians, Jordanians and Lebanese). This suggests that the genetic contribution of Arab invasion of 7th-11th century A.D. had little impact of the North African gene pool. PMID:26317228

  8. HLA Class I and Class II Alleles and Haplotypes Confirm the Berber Origin of the Present Day Tunisian Population.

    PubMed

    Hajjej, Abdelhafidh; Almawi, Wassim Y; Hattab, Lasmar; El-Gaaied, Amel; Hmida, Slama

    2015-01-01

    In view of its distinct geographical location and relatively small area, Tunisia witnessed the presence of many civilizations and ethnic groups throughout history, thereby questioning the origin of present-day Tunisian population. We investigated HLA class I and class II gene profiles in Tunisians, and compared this profile with those of Mediterranean and Sub-Sahara African populations. A total of 376 unrelated Tunisian individuals of both genders were genotyped for HLA class I (A, B) and class II (DRB1, DQB1), using reverse dot-blot hybridization (PCR-SSO) method. Statistical analysis was performed using Arlequin software. Phylogenetic trees were constructed by DISPAN software, and correspondence analysis was carried out by VISTA software. One hundred fifty-three HLA alleles were identified in the studied sample, which comprised 41, 50, 40 and 22 alleles at HLA-A,-B,-DRB1 and -DQB1 loci, respectively. The most frequent alleles were HLA-A*02:01 (16.76%), HLA-B*44:02/03 (17.82%), HLA-DRB1*07:01 (19.02%), and HLA-DQB1*03:01 (17.95%). Four-locus haplotype analysis identified HLA-A*02:01-B*50:01-DRB1*07:01-DQB1*02:02 (2.2%) as the common haplotype in Tunisians. Compared to other nearby populations, Tunisians appear to be genetically related to Western Mediterranean population, in particular North Africans and Berbers. In conclusion, HLA genotype results indicate that Tunisians are related to present-day North Africans, Berbers and to Iberians, but not to Eastern Arabs (Palestinians, Jordanians and Lebanese). This suggests that the genetic contribution of Arab invasion of 7th-11th century A.D. had little impact of the North African gene pool. PMID:26317228

  9. Present-day oxidative subsidence of organic soils and mitigation in the Sacramento-San Joaquin Delta, California, USA

    NASA Astrophysics Data System (ADS)

    Deverel, Steven J.; Ingrum, Timothy; Leighton, David

    2016-05-01

    Subsidence of organic soils in the Sacramento-San Joaquin Delta threatens sustainability of the California (USA) water supply system and agriculture. Land-surface elevation data were collected to assess present-day subsidence rates and evaluate rice as a land use for subsidence mitigation. To depict Delta-wide present-day rates of subsidence, the previously developed SUBCALC model was refined and calibrated using recent data for CO2 emissions and land-surface elevation changes measured at extensometers. Land-surface elevation change data were evaluated relative to indirect estimates of subsidence and accretion using carbon and nitrogen flux data for rice cultivation. Extensometer and leveling data demonstrate seasonal variations in land-surface elevations associated with groundwater-level fluctuations and inelastic subsidence rates of 0.5-0.8 cm yr-1. Calibration of the SUBCALC model indicated accuracy of ±0.10 cm yr-1 where depth to groundwater, soil organic matter content and temperature are known. Regional estimates of subsidence range from <0.3 to >1.8 cm yr-1. The primary uncertainty is the distribution of soil organic matter content which results in spatial averaging in the mapping of subsidence rates. Analysis of leveling and extensometer data in rice fields resulted in an estimated accretion rate of 0.02-0.8 cm yr-1. These values generally agreed with indirect estimates based on carbon fluxes and nitrogen mineralization, thus preliminarily demonstrating that rice will stop or greatly reduce subsidence. Areas below elevations of -2 m are candidate areas for implementation of mitigation measures such as rice because there is active subsidence occurring at rates greater than 0.4 cm yr-1.

  10. A High-resolution 3D Geodynamical Model of the Present-day India-Asia Collision System

    NASA Astrophysics Data System (ADS)

    Kaus, B.; Baumann, T.

    2015-12-01

    We present a high-resolution, 3D geodynamic model of the present-day India-Asia collision system. The model is separated into multiple tectonic blocks, for which we estimate the first order rheological properties and the impact on the dynamics of the collision system. This is done by performing systematic simulations with different rheologies to minimize the misfit to observational constraints such as the GPS-velocity field. The simulations are performed with the parallel staggered grid FD code LaMEM using a numerical resolution of at least 512x512x256 cells to resolve dynamically important shear zones reasonably well. A fundamental part of this study is the reconstruction of the 3D present-day geometry of Tibet and the adjacent regions. Our interpretations of crust and mantle lithosphere geometry are jointly based on a globally available shear wave tomography (Schaeffer and Lebedev, 2013) and the Crust 1.0 model (Laske et al. http://igppweb.ucsd.edu/~gabi/crust1.html). We regionally refined and modified our interpretations based on seismicity distributions and focal mechanisms and incorporated regional receiver function studies to improve the accuracy of the Moho in particular. Results suggest that we can identify at least one "best-fit" solution in terms of rheological model properties that reproduces the observed velocity field reasonably well, including the strong rotation of the GPS velocity around the eastern syntax of the Himalaya. We also present model co-variances to illustrate the trade-offs between the rheological model parameters, their respective uncertainties, and the model fit. Schaeffer, A.J., Lebedev, S., 2013. Global shear speed structure of the upper mantle and transition zone. Geophysical Journal International 194, 417-449. doi:10.1093/gji/ggt095

  11. Present-day oxidative subsidence of organic soils and mitigation in the Sacramento-San Joaquin Delta, California, USA

    NASA Astrophysics Data System (ADS)

    Deverel, Steven J.; Ingrum, Timothy; Leighton, David

    2016-03-01

    Subsidence of organic soils in the Sacramento-San Joaquin Delta threatens sustainability of the California (USA) water supply system and agriculture. Land-surface elevation data were collected to assess present-day subsidence rates and evaluate rice as a land use for subsidence mitigation. To depict Delta-wide present-day rates of subsidence, the previously developed SUBCALC model was refined and calibrated using recent data for CO2 emissions and land-surface elevation changes measured at extensometers. Land-surface elevation change data were evaluated relative to indirect estimates of subsidence and accretion using carbon and nitrogen flux data for rice cultivation. Extensometer and leveling data demonstrate seasonal variations in land-surface elevations associated with groundwater-level fluctuations and inelastic subsidence rates of 0.5-0.8 cm yr-1. Calibration of the SUBCALC model indicated accuracy of ±0.10 cm yr-1 where depth to groundwater, soil organic matter content and temperature are known. Regional estimates of subsidence range from <0.3 to >1.8 cm yr-1. The primary uncertainty is the distribution of soil organic matter content which results in spatial averaging in the mapping of subsidence rates. Analysis of leveling and extensometer data in rice fields resulted in an estimated accretion rate of 0.02-0.8 cm yr-1. These values generally agreed with indirect estimates based on carbon fluxes and nitrogen mineralization, thus preliminarily demonstrating that rice will stop or greatly reduce subsidence. Areas below elevations of -2 m are candidate areas for implementation of mitigation measures such as rice because there is active subsidence occurring at rates greater than 0.4 cm yr-1.

  12. Similarities in the Spatial Pattern of the Surface Flux Response to Present-Day Greenhouse Gases and Aerosols

    NASA Astrophysics Data System (ADS)

    Persad, G.; Ming, Y.; Ramaswamy, V.

    2014-12-01

    Recent studies suggest that present-day greenhouse gases (GHGs) and aerosols can produce remarkably similar patterns of climate response in fully coupled general circulation model (GCM) simulations, despite having significantly different spatial patterns of top-of-atmosphere (TOA) forcing. However, there is little understanding of the mechanisms of ocean-atmosphere interaction that could lead to the response pattern formation. Surface flux perturbations are a crucial pathway by which TOA forcing is communicated to the ocean, and may be a vital link in explaining the spatial similarities in the fully coupled responses to disparate TOA forcing patterns—a phenomenon with implications for detection and attribution, as well as the climate sensitivity to different forcers. We analyze the surface energy budget response to present-day aerosols versus GHGs in single forcing, fixed SST, atmospheric GCM experiments to identify mechanisms for response pattern formation via surface flux perturbations. We find that, although the TOA forcing spatial patterns of GHGs and aerosols are largely uncorrelated, their surface radiative and heat flux patterns are significantly anti-correlated. Furthermore, this anti-correlation is largely explained by similar (but sign-reversed) spatial patterns of surface latent and sensible heat flux response to the two forcers, particularly over the winter-hemisphere extratropical oceans. These are, in turn, driven by spatially similar perturbations in surface winds from changes in mean tropical and midlatitude circulation. These results suggest that the mean atmospheric circulation, which has many anti-symmetric responses to GHG and aerosol forcings, is an efficient homogenizer of spatial patterns in the surface heat flux response to heterogeneous TOA forcings, creating an atmosphere-only pathway for similarities in the fully coupled response.

  13. Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tropical cyclone-induced storm surges

    NASA Astrophysics Data System (ADS)

    Haigh, Ivan D.; MacPherson, Leigh R.; Mason, Matthew S.; Wijeratne, E. M. S.; Pattiaratchi, Charitha B.; Crompton, Ryan P.; George, Steve

    2014-01-01

    The incidence of major storm surges in the last decade have dramatically emphasized the immense destructive capabilities of extreme water level events, particularly when driven by severe tropical cyclones. Given this risk, it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood and erosion management, engineering and for future land-use planning and to ensure the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. Australia has a long history of coastal flooding from tropical cyclones. Using a novel integration of two modeling techniques, this paper provides the first estimates of present day extreme water level exceedance probabilities around the whole coastline of Australia, and the first estimates that combine the influence of astronomical tides, storm surges generated by both extra-tropical and tropical cyclones, and seasonal and inter-annual variations in mean sea level. Initially, an analysis of tide gauge records has been used to assess the characteristics of tropical cyclone-induced surges around Australia. However, given the dearth (temporal and spatial) of information around much of the coastline, and therefore the inability of these gauge records to adequately describe the regional climatology, an observationally based stochastic tropical cyclone model has been developed to synthetically extend the tropical cyclone record to 10,000 years. Wind and pressure fields derived for these synthetically generated events have then been used to drive a hydrodynamic model of the Australian continental shelf region with annual maximum water levels extracted to estimate exceedance probabilities around the coastline. To validate this methodology, selected historic storm surge events have been simulated and resultant storm surges compared with gauge records. Tropical cyclone induced exceedance probabilities have been combined with

  14. Complex Bedforms and Complex Water Masses: A Case Study from the Tertiary to Present-day, Pelotas Basin, Offshore Uruguay

    NASA Astrophysics Data System (ADS)

    Thompson, P.; Badalini, G.; Wrigley, S.; Walker, R.; Argent, J.; Hernandez-Molina, J.; de Santa Ana, H.; Soto, M.; Tomasini, J.

    2015-12-01

    varied both spatially and temporally and operated at various water depths. This complexity continues Present-day and is spectacularly imaged by pseudo time-lapse seismic data from the Present-day water column. These data, which are commonly neglected, highlight the true complexity of ocean currents and show how discrete dynamic water masses mix and move over time.

  15. Volcanoes and the environment: Lessons for understanding Earth's past and future from studies of present-day volcanic emissions

    NASA Astrophysics Data System (ADS)

    Mather, Tamsin A.

    2015-10-01

    Volcanism has affected the environment of our planet over a broad range of spatial (local to global) and temporal (< 1 yr to 100s Myr) scales and will continue to do so. As well as examining the Earth's geological record and using computer modelling to understand these effects, much of our knowledge of these processes comes from studying volcanism on the present-day planet. Understanding the full spectrum of possible routes and mechanisms by which volcanism can affect the environment is key to developing a realistic appreciation of possible past and potential future volcanic impact scenarios. This review paper seeks to give a synoptic overview of these potential mechanisms, focussing on those that we can seek to understand over human timescales by studying current volcanic activity. These effects are wide ranging from well-documented planetary-scale impacts (e.g., cooling by stratospheric aerosol veils) to more subtle or localised processes like ash fertilisation of ocean biota and impacts on cloud properties, atmospheric oxidant levels and terrestrial ecosystems. There is still much to be gained by studying present-day volcanic emissions. This review highlights the need for further work in three example areas. Firstly, to understand regional and arc-scale volcanic emissions, especially cycling of elements through subduction zones, more volatile measurements are needed to contribute to a fundamental and systematic understanding of these processes throughout geological time. Secondly, there is still uncertainty surrounding whether stratospheric ozone depletion following volcanic eruptions results solely from activation of anthropogenic halogen species. We should be poised to study future eruptions into the stratosphere with regard to their impacts and halogen load and work to improve our models and understanding of the relevant underlying processes within the Earth and the atmosphere. Thirdly, we lack a systematic understanding of trace metal volatility from magmas

  16. Global connections between aeolian dust, climate and ocean biogeochemistry at the present day and at the last glacial maximum

    NASA Astrophysics Data System (ADS)

    Maher, B. A.; Prospero, J. M.; Mackie, D.; Gaiero, D.; Hesse, P. P.; Balkanski, Y.

    2010-04-01

    Palaeo-dust records in sediments and ice cores show that wind-borne mineral aerosol ('dust') is strongly linked with climate state. During glacial climate stages, for example, the world was much dustier, with dust fluxes two to five times greater than in interglacial stages. However, the influence of dust on climate remains a poorly quantified and actively changing element of the Earth's climate system. Dust can influence climate directly, by the scattering and absorption of solar and terrestrial radiation, and indirectly, by modifying cloud properties. Dust transported to the oceans can also affect climate via ocean fertilization in those regions of the world's oceans where macronutrients like nitrate are abundant but primary production and nitrogen fixation are limited by iron scarcity. Dust containing iron, as fine-grained iron oxides/oxyhydroxides and/or within clay minerals, and other essential micronutrients (e.g. silica) may modulate the uptake of carbon in marine ecosystems and, in turn, the atmospheric concentration of CO 2. Here, in order to critically examine past fluxes and possible climate impacts of dust in general and iron-bearing dust in particular, we consider present-day sources and properties of dust, synthesise available records of dust deposition at the last glacial maximum (LGM); evaluate the evidence for changes in ocean palaeo-productivity associated with, and possibly caused by, changes in aeolian flux to the oceans at the LGM; and consider the radiative forcing effects of increased LGM dust loadings.

  17. Atmospheric transport of persistent organic pollutants to and from the Arctic under present-day and future climate.

    PubMed

    Octaviani, Mega; Stemmler, Irene; Lammel, Gerhard; Graf, Hans F

    2015-03-17

    The long-term atmospheric cycling and fate of persistent organic pollutants under the influence of a changing climate is a concern. A GCM's realization of present-day (1970-1999) and future (2070-2099) climate, the latter under a medium scenario of greenhouse gas emissions, is used to study meridional transports and their correlations with the Arctic and North Atlantic Oscillations (AO and NAO). Regions of import and export maxima into the Arctic are identified along the Arctic Circle. It is found that, under future climate conditions, the net export of PCB153 out of the Arctic will increase. The meridional net flux pattern of this substance is expected to become independent of AO and NAO. For DDT, a trend of decreasing net Arctic import will reverse to an increasing trend 100 years after peak emission, which is partly due to more frequent AO and NAO positive phases. It is concluded that the long-term accumulation trends in the Arctic of other persistent pollutants, including so-called emerging pollutants, are subject to the substances' specific behavior and fate in the environment and need to be studied specifically. PMID:25686012

  18. Evaluation of Present-day Aerosols over China Simulated from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Liao, H.; Chang, W.

    2014-12-01

    High concentrations of aerosols over China lead to strong radiative forcing that is important for both regional and global climate. To understand the representation of aerosols in China in current global climate models, we evaluate extensively the simulated present-day aerosol concentrations and aerosol optical depth (AOD) over China from the 12 models that participated in Atmospheric Chemistry & Climate Model Intercomparison Project (ACCMIP), by using ground-based measurements and satellite remote sensing. Ground-based measurements of aerosol concentrations used in this work include those from the China Meteorological Administration (CMA) Atmosphere Watch Network (CAWNET) and the observed fine-mode aerosol concentrations collected from the literature. The ground-based measurements of AOD in China are taken from the AErosol RObotic NETwork (AERONET), the sites with CIMEL sun photometer operated by Institute of Atmospheric Physics, Chinese Academy of Sciences, and from Chinese Sun Hazemeter Network (CSHNET). We find that the ACCMIP models generally underestimate concentrations of all major aerosol species in China. On an annual mean basis, the multi-model mean concentrations of sulfate, nitrate, ammonium, black carbon, and organic carbon are underestimated by 63%, 73%, 54%, 53%, and 59%, respectively. The multi-model mean AOD values show low biases of 20-40% at studied sites in China. The ACCMIP models can reproduce seasonal variation of nitrate but cannot capture well the seasonal variations of other aerosol species. Our analyses indicate that current global models generally underestimate the role of aerosols in China in climate simulations.

  19. Model sensitivity of ice flux over the grounding line to present-day climatic forcing and geothermal flux

    NASA Astrophysics Data System (ADS)

    Kleiner, Thomas; Humbert, Angelika

    2016-04-01

    Large uncertainties remain in the current and future contribution to sea level change from Antarctica from observations and numerical flow modelling. Within the SeaRISE project atmospheric, oceanic, and subglacial forcing scenarios were applied to different ice-sheet models to assess Antarctic ice sheet sensitivity over a 500 year timescale. The scenario results have been compared to the individual state of each model at the end of its spin-up. It has been shown, that the model results highly depend on the chosen climate forcing and spin-up strategy. Here we use the Parallel Ice Sheet Model (PISM) to perform spin-up simulations across different data sets for present-day boundary conditions for the Antarctic Ice Sheet (surface temperature, surface mass balance and geothermal flux). The utilized spin-up methods include free evolving and geometry constrained simulations. Here we present our analysis of the ice flux over the grounding line for each set-up and compare the fluxes from large drainage basin units with estimates derived from remote sensing.

  20. Present-Day Crustal Vertical Motion Around the Ordos Block Constrained by Precise Leveling and GPS Data

    NASA Astrophysics Data System (ADS)

    Hao, Ming; Wang, Qingliang; Cui, Duxin; Liu, Liwei; Zhou, Lin

    2016-09-01

    Precise leveling data observed in the period of 1970-2014 around the Ordos block were collected and processed to estimate present-day crustal vertical movement. Vertical rates of 6 GPS sites were employed as a priori constraints to define the reference frame. The velocity field shows that the interior of the Ordos block moves upward at a rate of 3 mm/a as a stable block. With respect to the central Ordos, the grabens and rifts around the Ordos block are undergoing subsidence, while the northeastern and southwestern Ordos uplift at the average rates of 2 and 1 mm/a, respectively. To the southeastern margin of the Ordos block, the Weihe and southern Shanxi grabens are subsiding at the rates of 4-6 mm/a. The subsidence of the Shanxi graben indicates that the graben is experiencing extensional movement on a long timescale. To the northwestern margin of the Ordos block, the Hetao and Yinchuan rifts are subsiding at the rates of 2-3 mm/a. A 2-D buried faulting model is used to infer the normal or reverse dip-slip rates. Our solution shows that most of the normal slip rates along the faults in the grabens and rifts are ~2 mm/a.

  1. Present-Day Crustal Vertical Motion Around the Ordos Block Constrained by Precise Leveling and GPS Data

    NASA Astrophysics Data System (ADS)

    Hao, Ming; Wang, Qingliang; Cui, Duxin; Liu, Liwei; Zhou, Lin

    2016-06-01

    Precise leveling data observed in the period of 1970-2014 around the Ordos block were collected and processed to estimate present-day crustal vertical movement. Vertical rates of 6 GPS sites were employed as a priori constraints to define the reference frame. The velocity field shows that the interior of the Ordos block moves upward at a rate of 3 mm/a as a stable block. With respect to the central Ordos, the grabens and rifts around the Ordos block are undergoing subsidence, while the northeastern and southwestern Ordos uplift at the average rates of 2 and 1 mm/a, respectively. To the southeastern margin of the Ordos block, the Weihe and southern Shanxi grabens are subsiding at the rates of 4-6 mm/a. The subsidence of the Shanxi graben indicates that the graben is experiencing extensional movement on a long timescale. To the northwestern margin of the Ordos block, the Hetao and Yinchuan rifts are subsiding at the rates of 2-3 mm/a. A 2-D buried faulting model is used to infer the normal or reverse dip-slip rates. Our solution shows that most of the normal slip rates along the faults in the grabens and rifts are ~2 mm/a.

  2. A novel GIS-based tool for estimating present-day ocean reference depth using automatically processed gridded bathymetry data

    NASA Astrophysics Data System (ADS)

    Jurecka, Mirosława; Niedzielski, Tomasz; Migoń, Piotr

    2016-05-01

    This paper presents a new method for computing the present-day value of the reference depth (dr) which is an essential input information for assessment of past sea-level changes. The method applies a novel automatic geoprocessing tool developed using Python script and ArcGIS, and uses recent data about ocean floor depth, sediment thickness, and age of oceanic crust. The procedure is multi-step and involves creation of a bathymetric dataset corrected for sediment loading and isostasy, delineation of subduction zones, computation of perpendicular sea-floor profiles, and statistical analysis of these profiles versus crust age. The analysis of site-specific situations near the subduction zones all around the world shows a number of instances where the depth of the oceanic crust stabilizes at a certain level before reaching the subduction zone, and this occurs at depths much lower than proposed in previous approaches to the reference depth issue. An analysis of Jurassic and Cretaceous oceanic lithosphere shows that the most probable interval at which the reference depth occurs is 5300-5800 m. This interval is broadly consistent with dr estimates determined using the Global Depth-Heatflow model (GDH1), but is significantly lower than dr estimates calculated on a basis of the Parsons-Sclater Model (PSM).

  3. Natural change and human impact in a present-day fluvial catchment: The Geul River, Southern Netherlands

    NASA Astrophysics Data System (ADS)

    Vandenberghe, J.; de Moor, J. J. W.; Spanjaard, G.

    2012-07-01

    The Geul River has a long history of channel straightening and bank protection, but also has several natural meandering parts. In addition, some formerly 'fixed' or 'protected' stretches of the river have been allowed to meander freely since 1988. Therefore, it represents an ideal case for evaluating the contribution of human interference to the intrinsic evolution of the river. In this paper, we compare the response of selected (not protected) reaches of the present-day river to different human modifications. The river banks were labelled as "stable", "unstable" or "erosive". As might be expected, stretches with a high sinuosity have a high percentage of erosive and unstable bank length, while low-sinuosity stretches experience hardly any erosion. The amount of lateral erosion and sedimentation in natural situations is compared with that in situations with different bank protection and stabilization types. Erosion rates may locally attain up to 2 m per year. Detailed grain-size analysis of point-bar sections enable distinction of successive fining-up sequences. Vertical aggradation rates within the point-bars are up to 0.15 m yr- 1. The highest rates are found in the youngest point-bars. Collectively, the results of this study show that when bank protection is removed, the freely meandering river creates its own specific ecosystems and retention capacity increases. Such a return to natural environmental and ecological conditions is in accordance with the objectives of the European Water Framework Directive.

  4. Transient climate simulation from the Maunder Minimum to present day using prescribed changes in GHG, total/spectral solar irradiance and ozone

    NASA Astrophysics Data System (ADS)

    Spangehl, Thomas; Cubasch, Ulrich; Schimanke, Semjon

    A fully coupled AO-GCM including representation of the middle atmosphere is used for tran-sient simulation of climate from 1630 to 2000 AD. For better representation of changes in the UV/visible part of the solar spectrum an improved short-wave radiation scheme is implemented. The model is driven by changes in GHG concentrations, solar activity and volcanic eruptions. Solar variability is introduced via changes in total/spectral solar irradiance (TSI/SSI) and pre-scribed changes in stratospheric ozone. The secular trend in TSI is in the range of 0.1 percent increase from Maunder Minimum to present-day. Volcanic eruptions are represented via abrupt reduction in TSI. With the applied forcings the model does not simulate a clear reduction of the annual Northern Hemisphere (NH) mean near surface temperature during Maunder Minimum. By contrast the Dalton Minimum is characterized by distinct cooling and there is a significant raise of NH mean near surface temperature until the end of the 20th century. Focusing on the North Atlantic/European region the winter mean near surface temperature change pat-tern from Late Maunder Minimum (1675-1715) to present-day (1960-1990) reveals maximum warming over north-eastern Europe and cooling over the western North Atlantic with maxi-mum cooling west of Greenland. These changes can partly be explained by a shift of the NAO towards a more positive phase. The simulated changes in tropospheric circulation are discussed with special emphasize on the role of the solar forcing. Besides the stratospheric solar forcing which may affect NAO variability via downward propagation of the solar signal from the strato-sphere to the troposphere the magnitude of the secular trend in TSI might play a role. For the period from Maunder Minimum to present-day the simulation shows less near surface temper-ature increase especially over arctic regions when compared to simulations performed with the same model including the standard radiation scheme but

  5. Present-day deformation in NE Iran and the South Caspian constraint by Global Positioning System measurements

    NASA Astrophysics Data System (ADS)

    Mousavi, Z.; Walpersdorf, A.; Walker, R. T.; Tavakoli, F.; Pathier, E.; Nankali, H.; Nilfouroushan, F.; Aghamohammadi, A.; Djamour, Y.

    2012-12-01

    The continental collision between Arabia, the Eurasia and distribution of earthquake epicenters show that most of the deformation is accommodated within the political borders of Iran. In recent years, constraints from GPS, seismology and geological estimates of fault slip-rate have allowed considerable advances in understanding the rates and kinematics of faulting across many parts of Iran. However, until now, only little is known on the present-day distribution of strain across the eastern and northeastern parts of the country, such that it has been difficult to assess the rates of faulting, the related earthquake hazard, and the relationship between the active faults and the overall tectonic motions. This area is one of the most densely populated regions of Iran with almost 6.5 million habitants and a significant number of historical earthquakes like the Qumis 856 A.D earthquake with 200.000 victims. But while eastern Alborz and Kopeh Dagh are clearly regions of active faulting, a lack of instrumental earthquakes is presently observed, making this area particularly interesting for hazard assessment studies. The sparse GPS measurements in NE Iran provide only limited constraints on the applicability of different kinematic scenarios that have been proposed to explain the role of the observed faults. Here, we present a velocity field, composed from 47 GPS stations (20 campaign and 27 permanent), recording over up to 11 years, and covering the entire NE of Iran. This new GPS velocity field helps to investigate how northward directed Arabia-Eurasia shortening is accommodated at the northern boundary of the deforming zone. A regional deformation field for NE Iran has been estimated from the GPS measurements. It shows how the incoming ~7 mm/yr of NS shortening between Central Iran and Eurasia is accommodated in Alborz, Binalud and Kopeh Dagh. The shortening rate decreases toward the east and dies out at the Afghanistan border. The deformation pattern is contrasted along

  6. The Herschel view of the dominant mode of galaxy growth from z = 4 to the present day

    NASA Astrophysics Data System (ADS)

    Schreiber, C.; Pannella, M.; Elbaz, D.; Béthermin, M.; Inami, H.; Dickinson, M.; Magnelli, B.; Wang, T.; Aussel, H.; Daddi, E.; Juneau, S.; Shu, X.; Sargent, M. T.; Buat, V.; Faber, S. M.; Ferguson, H. C.; Giavalisco, M.; Koekemoer, A. M.; Magdis, G.; Morrison, G. E.; Papovich, C.; Santini, P.; Scott, D.

    2015-03-01

    our findings on the cosmic SFR history and on the origin of present-day stars: more than two-thirds of present-day stars must have formed in a regime dominated by the "main sequence" mode. As a consequence we conclude that, although omnipresent in the distant Universe, galaxy mergers had little impact in shaping the global star formation history over the last 12.5 billion years. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices are available in electronic form at http://www.aanda.org

  7. The Secrets of the Nearest Starburst Cluster. II. The Present-Day Mass Function in NGC 3603

    NASA Astrophysics Data System (ADS)

    Stolte, Andrea; Brandner, Wolfgang; Brandl, Bernhard; Zinnecker, Hans

    2006-07-01

    Based on deep Very Large Telescope Infrared Spectrometer and Array Camera JHK photometry, we have derived the present-day mass function (MF) of the central starburst cluster NGC 3603 YC (Young Cluster) in the giant H II region NGC 3603. The effects of field contamination, individual reddening, and a possible binary contribution are investigated. The MF slopes resulting from the different methods are compared and lead to a surprisingly consistent cluster MF with a slope of Γ=-0.9+/-0.15. Analyzing different radial annuli around the cluster core, no significant change in the slope of the MF is observed. However, mass segregation in the cluster is evidenced by the increasing depletion of the high-mass tail of the stellar mass distribution with increasing radius. We discuss the indications of mass segregation with respect to the changes observed in the binned and cumulative stellar MFs and argue that the cumulative function, as well as the fraction of high- to low-mass stars, provides better indicators for mass segregation than the MF slope alone. Finally, the observed MF and starburst morphology of NGC 3603 YC are discussed in the context of massive local star-forming regions such as the Galactic center Arches cluster, R136/30 Dor in the LMC, and the Orion Trapezium cluster, all providing resolved templates for extragalactic star formation. Despite the similarity in the observed MF slopes, dynamical considerations suggest that the starburst clusters do not form gravitationally bound systems over a Hubble time. Both the environment (gravitational potential of the Milky Way) and the concentration of stars in the cluster core determine the dynamical stability of a dense star cluster, such that the long-term evolution of a starburst is not exclusively determined by the stellar evolution of its members, as frequently assumed for globular cluster systems. Based on observations obtained at the ESO Very Large Telescope on Paranal, Chile, under programs 63.I-0015 and 65.I

  8. Modeling of Present-Day Atmosphere and Ocean Non-Tidal De-Aliasing Errors for Future Gravity Mission Simulations

    NASA Astrophysics Data System (ADS)

    Bergmann-Wolf, I.; Dobslaw, H.; Mayer-Gürr, T.

    2015-12-01

    A realistically perturbed synthetic de-aliasing model consistent with the updated Earth System Model of the European Space Agency (Dobslaw et al., 2015) is now available for the years 1995 -- 2006. The data-set contains realizations of (i) errors at large spatial scales assessed individually for periods between 10 -- 30, 3 -- 10, and 1 -- 3 days, the S1 atmospheric tide, and sub-diurnal periods; (ii) errors at small spatial scales typically not covered by global models of atmosphere and ocean variability; and (iii) errors due to physical processes not represented in currently available de-aliasing products. The error magnitudes for each of the different frequency bands are derived from a small ensemble of four atmospheric and oceanic models. In order to demonstrate the plausibility of the error magnitudes chosen, we perform a variance component estimation based on daily GRACE normal equations from the ITSG-Grace2014 global gravity field series recently published by the University of Graz. All 12 years of the error model are used to calculate empirical error variance-covariance matrices describing the systematic dependencies of the errors both in time and in space individually for five continental and four oceanic regions, and daily GRACE normal equations are subsequently employed to obtain pre-factors for each of those matrices. For the largest spatial scales up to d/o = 40 and periods longer than 24 h, errors prepared for the updated ESM are found to be largely consistent with noise of a similar stochastic character contained in present-day GRACE solutions. Differences and similarities identified for all of the nine regions considered will be discussed in detail during the presentation.Dobslaw, H., I. Bergmann-Wolf, R. Dill, E. Forootan, V. Klemann, J. Kusche, and I. Sasgen (2015), The updated ESA Earth System Model for future gravity mission simulation studies, J. Geod., doi:10.1007/s00190-014-0787-8.

  9. Spatial distribution of precipitation annual cycles over South Africa in 10 CORDEX regional climate model present-day simulations

    NASA Astrophysics Data System (ADS)

    Favre, Alice; Philippon, Nathalie; Pohl, Benjamin; Kalognomou, Evangelia-Anna; Lennard, Christopher; Hewitson, Bruce; Nikulin, Grigori; Dosio, Alessandro; Panitz, Hans-Juergen; Cerezo-Mota, Ruth

    2016-03-01

    This study presents an evaluation of the ability of 10 regional climate models (RCMs) participating in the COordinated Regional climate Downscaling Experiment-Africa to reproduce the present-day spatial distribution of annual cycles of precipitation over the South African region and its borders. As found in previous studies, annual mean precipitation is quasi-systematically overestimated by the RCMs over a large part of southern Africa south of about 20°S and more strongly over South Africa. The spatial analysis of precipitation over the studied region shows that in most models the distribution of biases appears to be linked to orography. Wet biases are quasi-systematic in regions with higher elevation with inversely neutral to dry biases particularly in the coastal fringes. This spatial pattern of biases is particularly obvious during summer and specifically at the beginning of the rainy season (November and December) when the wet biases are found to be the strongest across all models. Applying a k-means algorithm, a classification of annual cycles is performed using observed precipitation data, and is compared with those derived from modeled data. It is found that the in-homogeneity of the spatial and temporal distribution of biases tends to impact the modeled seasonality of precipitation. Generally, the pattern of rainfall seasonality in the ensemble mean of the 10 RCMs tends to be shifted to the southwest. This spatial shift is mainly linked to a strong overestimation of convective precipitation at the beginning of the rainy season over the plateau inducing an early annual peak and to an underestimation of stratiform rainfall in winter and spring over southwestern South Africa.

  10. Changing black carbon transport to the Arctic from present day to the end of 21st century

    NASA Astrophysics Data System (ADS)

    Jiao, Chaoyi; Flanner, Mark G.

    2016-05-01

    Here we explore how climate warming under the Representative Concentration Pathway 8.5 (RCP8.5) impacts Arctic aerosol distributions via changes in atmospheric transport and removal processes. We modify the bulk aerosol module in the Community Atmosphere Model to track distributions and fluxes of 200 black carbon-like tracers emitted from different locations, and we conduct idealized experiments with and without active aerosol deposition. Changing wind patterns, studied in isolation, cause the Arctic burdens of tracers emitted from East Asia and West Europe during winter to increase about 20% by the end of the century while decreasing the Arctic burdens of North American emissions by about 30%. These changes are caused by an altered winter polar dome structure that results from Arctic amplification and inhomogeneous sea ice loss and surface warming, both of which are enhanced in the Chukchi Sea region. The resulting geostrophic wind favors Arctic transport of East Asian emissions while inhibiting poleward transport of North American emissions. When active deposition is also considered, however, Arctic burdens of emissions from northern midlatitudes show near-universal decline. This is a consequence of increased precipitation and wet removal, particularly within the Arctic, leading to decreased Arctic residence time. Simulations with present-day emissions of black carbon indicate a 13.6% reduction in the Arctic annual mean burden by the end of the 21st century, due to warming-induced transport and deposition changes, while simulations with changing climate and emissions under RCP8.5 show a 61.0% reduction.

  11. Historical and Present Day Mercury Contamination From Gold Mining in Three Feeding Guilds of Bats From the Peruvian Amazon

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Divoll, T.

    2014-12-01

    Miners in many countries use mercury as an amalgam to separate gold from river sediments. In the last twenty years the price of gold has risen and the number of small-scale, artisanal gold mining operations in the Amazon basin have also increased. The influx of mercury into natural river systems has detrimental consequences for the surrounding ecosystem and for organisms, particularly those at higher trophic levels. Toxic mercury levels have been shown to impair reproductive, neurological and behavioral functioning of organisms. I used bats (Chiroptera) as a mammalian model system to study mercury contamination and accumulation due to gold mining from field caught and museum collection specimens in Amazonian Perú and showed that: (1) Total mercury concentrations in Amazonian bat species have increased over time since the 1920's; (2) Bat species from sites with current active mining have higher concentrations of mercury than non-mining sites, with some species having levels exceeding those considered toxic for mammals; (3) Higher trophic levels of bats (piscivores and insectivores) bioaccumulate more mercury than bats of lower trophic levels (frugivores); (4) Bats located in present day uncontaminated sites have the same mercury levels as bats collected in the 1920's from the Amazon basin. The variety of bat feeding guilds allowed for a comparison of how mercury accumulation is affected by diet within one taxonomic order. The novel use of museum specimens allowed for a look back into the historical timeline of mercury contamination in the Amazon basin. Bats represent a new and exciting study system since, like humans, they are mammals and should therefore show similar neurochemical and behavioral responses to this toxic element.

  12. Impact of the Yakutat indentor corner on present-day tectonics and fault activity in SE Alaska - SW Yukon

    NASA Astrophysics Data System (ADS)

    Mazzotti, S.; Marechal, A.; Ritz, J. F.; Ferry, M. A.

    2015-12-01

    We present an active tectonic model of the SE Alaska - SW Yukon region based principally on the integration of recent GPS velocity data and new fault-slip rates derived from geomorphology. In this region, the Yakutat collision results in complex tectonics with patterns of strain localization and strain partitioning that strongly vary across the various mountain ranges and active faults. We propose that deformation and fault activity in the St. Elias and Chugach Mountains are primarily controlled by the eastern syntaxis of the Yakutat collision, which produces a semi-radial tectonic pattern: Velocities, principal horizontal shortening rates, and maximum horizontal stress orientations rotate by 60 - 80 ° around the syntaxis, from roughly parallel to the relative Pacific - North America motion at the front of the collision to roughly orthogonal southeast of the syntaxis. The interaction between this strain pattern and major inherited tectonic structures inland of the collision zone (i.e., Denali and Duke River Faults) results in various reactivation modes of these structures. Specifically, the Denali Fault shows a very pronounced lateral variations of activity from ~12 mm/a of dextral slip rate in its central section to ~1 mm/a of mostly shortening slip rate along its southern section. This marked change of activity is associated with a possible relay system where the Duke River and Totschunda Faults accommodate a major part (8 - 12 mm/a) of the inland strain transfer directly in front of the syntaxis. This new tectonic model retains some questions, in particular regarding the mechanisms of deformation and strain transfer (1) from the syntaxis to the Duke River - Totschunda system and (2) at the junction between Totschunda and Denali Faults. Numerical models of present-day deformation may help address these issues and provide information about relative strength of the various crustal and inherited fault elements of this system.

  13. Multivariate spatio-temporal modelling for assessing Antarctica's present-day contribution to sea-level rise

    PubMed Central

    Zammit-Mangion, Andrew; Rougier, Jonathan; Schön, Nana; Lindgren, Finn; Bamber, Jonathan

    2015-01-01

    Antarctica is the world's largest fresh-water reservoir, with the potential to raise sea levels by about 60 m. An ice sheet contributes to sea-level rise (SLR) when its rate of ice discharge and/or surface melting exceeds accumulation through snowfall. Constraining the contribution of the ice sheets to present-day SLR is vital both for coastal development and planning, and climate projections. Information on various ice sheet processes is available from several remote sensing data sets, as well as in situ data such as global positioning system data. These data have differing coverage, spatial support, temporal sampling and sensing characteristics, and thus, it is advantageous to combine them all in a single framework for estimation of the SLR contribution and the assessment of processes controlling mass exchange with the ocean. In this paper, we predict the rate of height change due to salient geophysical processes in Antarctica and use these to provide estimates of SLR contribution with associated uncertainties. We employ a multivariate spatio-temporal model, approximated as a Gaussian Markov random field, to take advantage of differing spatio-temporal properties of the processes to separate the causes of the observed change. The process parameters are estimated from geophysical models, while the remaining parameters are estimated using a Markov chain Monte Carlo scheme, designed to operate in a high-performance computing environment across multiple nodes. We validate our methods against a separate data set and compare the results to those from studies that invariably employ numerical model outputs directly. We conclude that it is possible, and insightful, to assess Antarctica's contribution without explicit use of numerical models. Further, the results obtained here can be used to test the geophysical numerical models for which in situ data are hard to obtain. © 2015 The Authors. Environmetrics published by John Wiley & Sons Ltd. PMID:25937792

  14. Life detection at a Mars analogue site of present-day serpentinization in the Tablelands Ophiolite of Newfoundland (Invited)

    NASA Astrophysics Data System (ADS)

    Morrill, P. L.; Szponar, N.; Brazelton, W. J.; Woodruff, Q.; Schrenk, M. O.; Bower, D. M.; Steele, A.

    2010-12-01

    The Tableland Ophiolite was created during the collision of Laurentia and Gondwana continents ca. 470 million years ago. Ultramafic mantle rocks, from the ancient sea bed that once separated these continents, were thrusted westward onto the old continental margin, which is now Western Newfoundland. Weathering due to recent glaciations has left large areas of ultramafic rock at the surface and created fissures for fluid flow. As a result serpentinization is occurring as fresh water penetrates the unaltered ultramafic rock. Serpentinization is of particular interest because, through hydration of ultramafic rock, this reaction produces H2 and the reducing conditions necessary for abiogenic hydrocarbon synthesis, while also producing conditions amenable for chemolithotrophic life. Therefore sites of active serpentinization can be the source of either abiogenic or biogenic organics, or both. Serpentinization is a suspected (past or present) source of (detected or putative) hydrocarbons on Mars, Titan and Europa, hence these astrobodies may be potentially habitable or once habitable environments. The Tablelands Ophiolite is an analogue site that is ideal for testing methods of life detection in an extreme environment of high pH and low microbial biomass characteristic of sites of serpentinization. Multiple ultrabasic reducing springs characteristic of present-day serpentinization have been identified and characterized based on their geochemistry and microbiology. Field-based instruments were deployed for the detection of microbial activity (ATP), microbial cell wall material, and mineralogy, in yet untested high pH and low biomass environment. In this talk I will give an overview of the in situ measurements of life detection and put these measurements in context of geochemistry, microbiology, carbon source and reaction pathways, and I will discuss what we have learned that will help us plan for future mission measurements.

  15. Dusty wind of W Hydrae. Multi-wavelength modelling of the present-day and recent mass loss

    NASA Astrophysics Data System (ADS)

    Khouri, T.; Waters, L. B. F. M.; de Koter, A.; Decin, L.; Min, M.; de Vries, B. L.; Lombaert, R.; Cox, N. L. J.

    2015-05-01

    Context. Low- and intermediate-mass stars go through a period of intense mass-loss at the end of their lives, during the asymptotic giant branch (AGB) phase. While on the AGB a significant part, or even most, of their initial mass is expelled in a stellar wind. This process controls the final stages of the evolution of these stars and contributes to the chemical evolution of galaxies. However, the wind-driving mechanism of AGB stars is not yet well understood, especially so for oxygen-rich sources. Characterizing both the present-day mass-loss rate and wind structure and the evolution of the mass-loss rate of such stars is paramount to advancing our understanding of this processes. Aims: We study the dusty wind of the oxygen-rich AGB star W Hya to understand its composition and structure and shed light on the mass-loss mechanism. Methods: We modelled the dust envelope of W Hya using an advanced radiative transfer code. We analysed our dust model in the light of a previously calculated gas-phase wind model and compared it with measurements available in the literature, such as infrared spectra, infrared images, and optical scattered light fractions. Results: We find that the dust spectrum of W Hya can partly be explained by a gravitationally bound dust shell that probably is responsible for most of the amorphous Al2O3 emission. The composition of the large (~0.3 μm) grains needed to explain the scattered light cannot be constrained, but probably is dominated by silicates. Silicate emission in the thermal infrared was found to originate from beyond 40 AU from the star. In our model, the silicates need to have substantial near-infrared opacities to be visible at such large distances. The increase in near-infrared opacity of the dust at these distances roughly coincides with a sudden increase in expansion velocity as deduced from the gas-phase CO lines. The dust envelope of W Hya probably contains an important amount of calcium but we were not able to obtain a dust

  16. Comparison of statistical and dynamical downscaling of extreme precipitations over France in present-day and future climate

    NASA Astrophysics Data System (ADS)

    Colin, Jeanne; Déqué, Michel; Sanchez Gomez, Emila; Somot, Samuel

    2010-05-01

    We present a comparison of two downscaling methods of extreme precipitations over France at a climatic time scale : a dynamical one performed with the Regional Climate Model ALADIN-Climate used at a resolution of 12 km, and a statistical one based on the weather regime approach and using the analog methodology to reconstruct daily fields of precipitations at a 8 km resolution. We focus on the most heavy precipitations of the area of interest, which occur in southeastern France in Autumn. Those involve small-scale processes than can be explicitly resolved only with 2-1 km resolution non-hydrostatic models. However, such models can not be used for climate simulations because of their computational cost is still too high. Yet these extreme events cause rather heavy damages, so that their possible evolution in the context of climate change is of great concern. Thus, there is strong need in assessing downscaling methods' ability to represent them. First, we downscale the low-resolution ERA40 re-analysis over the 1958-2000 time period with ALADIN-Climate, and from the year 1980 to the year 2000 with the statistical method. Then, we apply a quantile-quantile correction to the daily precipitations of the last twenty years of the ALADIN-Climate simulation. The correction rates are computed over the first part of the simulation (1958-1979) using a high-resolution gridded database : the SAFRAN analysis, which provides series of hourly fields for the 1958-2008 period over the french territory at a 8 km resolution. We assess the performances of each downscaling method in present-day climate by comparing the simulated precipitations to the SAFRAN database. The use of the ERA40 re-analysis allows to reproduce the real chronology in both downscalings, which enables to analyze the results not only from a statistical point of view but also through day-to-day diagnosis such as time correlations or spatial patterns of rain for given extreme events. Secondly, we apply these downscaling

  17. Investigating the Present Day Cosmic Dust Flux at the Earth's Surface: Initial Results from the Kwajalein Micrometeorite Collection

    NASA Technical Reports Server (NTRS)

    Wozniakiewicz, P. J.; Bradley, J. P.; Price, M. C.; Zolensky, M. E.; Ishii, H. A.; Brownlee, D. E.; Russell, S. S.

    2014-01-01

    Examination of impact craters on the Long Duration Exposure Facility satellite indicate a present day micrometeoroid flux of approx. 30,000 tonnes [1 after 2]. But what portion of this material arrives at the Earth's surface as micrometeorites? Studies of available micrometeorite collections from deep sea sediments [e.g. 3], Greenland blue ice [e.g. 4] and the South Pole water well [e.g. 1] may be complicated by terrestrial weathering and, in some cases, collection bias (magnetic separation for deep sea sediments) and poorly constrained ages. We have recently set up a micrometeorite collection station on Kwajalein Island in the Republic of the Marshall Islands in the Pacific Ocean, using high volume air samplers to collect particles directly from the atmosphere. By collecting in this way, the terrestrial age of the particles is known, the weathering they experience is minimal, and we are able to constrain particle arrival times. Collecting at this location also exploits the considerably reduced anthropogenic background [5]. Method: High volume air samplers were installed on top of the two-story airport building on Kwajalein. These were fitted with polycarbonate membrane filters with 5µm diameter perforations. The flow rates were set to 0.5m3/min, and filters were changed once a week. After collection, filters were washed to remove salt and concentrate particles [see 5] in preparation for analysis by SEM. Results and Discussion: A selection of filters have been prepared and surveyed. Due to their ease of identification our initial investigations have focused on particles resembling cosmic spherules. The spheres can be divided into three main groups: 1. Silicate spherules rich in Al, Ca, K and Na (to varying degrees), 2. Silicate spherules rich in Mg and Fe and 3. Fe-rich spherules. Group 1 spherules are often vesiculated and can occur as aggregates. They are similar in appearance and composition to volcanic microspheres [e.g. 6] and are thus likely terrestrial in

  18. High natural erosion rates are the backdrop for present-day soil erosion in the agricultural Middle Hills of Nepal

    NASA Astrophysics Data System (ADS)

    West, A. J.; Arnold, M.; AumaItre, G.; Bourles, D. L.; Keddadouche, K.; Bickle, M.; Ojha, T.

    2015-07-01

    Although agriculturally accelerated soil erosion is implicated in the unsustainable environmental degradation of mountain environments, such as in the Himalaya, the effects of land use can be challenging to quantify in many mountain settings because of the high and variable natural background rates of erosion. In this study, we present new long-term denudation rates, derived from cosmogenic 10Be analysis of quartz in river sediment from the Likhu Khola, a small agricultural river basin in the Middle Hills of central Nepal. Calculated long-term denudation rates, which reflect background natural erosion processes over 1000+ years prior to agricultural intensification, are similar to present-day sediment yields and to soil loss rates from terraces that are well maintained. Similarity in short- and long-term catchment-wide erosion rates for the Likhu is consistent with data from elsewhere in the Nepal Middle Hills but contrasts with the very large increases in short-term erosion rates seen in agricultural catchments in other steep mountain settings. Our results suggest that the large sediment fluxes exported from the Likhu and other Middle Hills rivers in the Himalaya are derived in large part from natural processes, rather than from soil erosion as a result of agricultural activity. Catchment-scale erosional fluxes may be similar over short and long timescales if both are dominated by mass wasting sources such as gullies, landslides, and debris flows (e.g., as is evident in the landslide-dominated Khudi Khola of the Nepal High Himalaya, based on compiled data). As a consequence, simple comparison of catchment-scale fluxes will not necessarily pinpoint land use effects on soils where these are only a small part of the total erosion budget, unless rates of mass wasting are also considered. Estimates of the mass wasting contribution to erosion in the Likhu imply catchment-averaged soil production rates on the order of ~ 0.25-0.35 mm yr-1, though rates of mass wasting are

  19. Modelling the economic losses of historic and present-day high-impact winter storms in Switzerland

    NASA Astrophysics Data System (ADS)

    Welker, Christoph; Stucki, Peter; Bresch, David; Dierer, Silke; Martius, Olivia; Brönnimann, Stefan

    2014-05-01

    Severe winter storms such as "Vivian" in February 1990 and "Lothar" in December 1999 are among the most destructive meteorological hazards in Switzerland. Disaster severity resulting from such windstorms is attributable, on the one hand, to hazardous weather conditions such as high wind gust speeds; and on the other hand to socio-economic factors such as population density, distribution of values at risk, and damage susceptibility. For present-day winter storms, the data basis is generally good to describe the meteorological development and wind forces as well as the associated socio-economic impacts. In contrast, the information on historic windstorms is overall sparse and the available historic weather and loss reports mostly do not provide quantitative information. This study illustrates a promising technique to simulate the economic impacts of both historic and present winter storms in Switzerland since end of the 19th century. Our approach makes use of the novel Twentieth Century Reanalysis (20CR) spanning 1871-present. The 2-degree spatial resolution of the global 20CR dataset is relatively coarse. Thus, the complex orography of Switzerland is not realistically represented, which has considerable ramifications for the representation of wind systems that are strongly influenced by the local orography, such as Föhn winds. Therefore, a dynamical downscaling of the 20CR to 3 km resolution using the Weather Research and Forecasting (WRF) model was performed, for in total 40 high-impact winter storms in Switzerland since 1871. Based on the downscaled wind gust speeds and the climada loss model, the estimated economic losses were calculated at municipality level for current economic and social conditions. With this approach, we find an answer to the question what would be the economic losses of e.g. a hazardous Föhn storm - which occurred in northern Switzerland in February 1925 - today, i.e. under current socio-economic conditions. Encouragingly, the pattern of

  20. Impact of urban emission on air-quality over central Europe: present day and future emissions perspective

    NASA Astrophysics Data System (ADS)

    Huszar, Peter; Belda, Michal; Halenka, Tomas; Karlicky, Jan

    2016-04-01

    The purpose of the study is to quantify the impact of present-day and future urban emission from central European cities on the regional air-quality (AQ), based on a modeling couple of the regional climate model RegCM4.2 and the chemistry transport model CAMx, including two-way interactions. A series of simulations was carried out for the present (2001-2010) decade and two future decades (2026-2035 and 2046-2055) either with all urban emissions included (base case) or without considering urban emissions. As we are interested on the impact of emission changes only, the impact of different driving meteorological conditions in the future (due to climate change) are not considered. The emissions used is the TNO MEGAPOLI European emission database that includes country/sector based scenarios for years 2030 and 2050, which were used for the encompassing decades. Further, the sensitivity of ozone production to urban emissions was examined by performing reduction experiments with -20% emission perturbation of NOx and/or NMVOC. The model was also validated using surface measurements of key pollutants. Selected air-quality measures were used as metrics describing the cities emission impact on regional air pollution. Due to urban emissions, significant ozone titration occurs over cities while over rural areas further from, ozone production is modeled, mainly in terms of number of exceedances and accumulated exceedances over the threshold of 40 ppbv. Urban NOx, SO2 and PM2.5 emissions also significantly contribute to concentrations in the cities themselves (up to 50-70% for NOx and SO2 , and up to 55% for PM2.5), but the contribution is large over rural areas as well (10-20%). Although air pollution over cities is largely determined by the local urban emissions, considerable (often a few tens of %) fraction of the concentration is attributable to other sources from rural areas and minor cities. The future urban emission AQ fingerprint is, in general, slightly smaller than in

  1. Present-day vertical displacements in the north-western Alps and southern Jura Mountains: Data from leveling comparisons

    NASA Astrophysics Data System (ADS)

    Jouanne, F.; MéNard, G.; Darmendrail, X.

    1995-06-01

    Two high-precision leveling networks were successively surveyed in France, the NGF, measured during the 1886-1907 period, and the IGN69, measured from 1965 to 1979. The accuracy of these levelings (standard deviation of 1.8mm/√km to 3.8mm/√km) allows us to compute the vertical displacements of the benchmarks between two different eras. The results indicate the occurrence of discrete zones of uplift and subsidence: (1) a regional uplift (up to 1.4 mm/yr) of the Subalpine Massifs; (2) an important uplift of the internal Jura (up to 2 mm/yr); (3) a relative subsidence of the southern part of the Jura (0.8 mm/yr); and (4) a relative subsidence of the Bresse Basin with respect to the external Jura. Comparing the spatial distribution of zones of uplift and their respective vertical displacement rates with a regional structural cross section leads to the conclusion that present-day uplift of the Belledonne and Bornes Massifs and of the internal parts of the Jura Mountains, can be explained by crustal shortening along a major basement-involving thrust fault. This fault ramps up under the Bornes Massif from a depth of 12 km to 7 km, turns into a flat under the Molasse Basin, ramps up to the top of the basement at the north-eastern margin of the internal Jura Mountains, and reaches the surface in the external Jura. The Salève ramp-anticline is carried by a bifurcation of this thrust. Horizontal displacement rates of 6 mm/yr at the Bornes ramp, 2 mm/yr at the Salève ramp, and 4 mm/yr at the internal Jura ramp have been determined by inversion of profiles of uplift rates. Whether this basement-involving thrust fault was already active during the Miocene main folding phase of the Jura Mountains or whether it was activated only during Pliocene-Pleistocene times is subject to debate.

  2. Effects of the past- and present-day ice melting on observed uplift rates in Southeast Alaska

    NASA Astrophysics Data System (ADS)

    Sato, T.; Larsen, C. F.; Miura, S.; Ohta, Y.; Fujimoto, H.; Sun, W.; Sugano, T.; Kaufman, A. M.; Motyka, R. J.; Freymueller, J. T.

    2009-12-01

    A joint Japanese-US observation project called ISEA (International geodetic project in South-Eastern Alaska) was initiated in 2005 to follow up the work of the University of Alaska Fairbanks (UAF) by adding new geodetic data sets (Miura et al., 2007). Based on 91 improved GPS velocities and the proposed ice loss models by Larsen et al. (2004, 2005, 2007) and by Tushingham and Peltier (1991), we estimated three effects: present-day ice melting (PDIM), post-little ice age (LIA) melting, and deglaciation following the last glacier maximum (LGM). We also have reevaluated the thickness of lithosphere and the viscosities of the mantle including that of asthenosphere in the region. The effects of LGM deglaciation were computed based on the ICE3G model (Tushingham and Peltier, 1991). Although the effect of LGM ice is small in SE-AK (i.e. 2 mm/yr at the maximum), we have confirmed that, by comparing with the misfits obtained by correcting for only two effects of PDIM and LIA, correcting for the LGM effect can improve the chi^2 of misfits by about 0.5 %. We estimated the effect of post-LIA ice melting based on the melting history proposed by Larsen et al. (2004, 2005). For the viscoelastic structure, we have tested two different kinds of mantle viscosity structure: a two-layer model similar to the model used by Larsen et al. (2005) and a 4-layer model. To search the best combination of the lithosphere thickness and the mantle viscosities, the combinations of the rheological parameters tested here were 161 in total number. To test the sensitivity of the estimated rheological parameters to the elastic PDIM effects, we have compared two PDIM models; one is EPSL2005 model (Larsen et al., 2005) and the other is JGR2007 model (Larsen et al., 2007). Statistical examinations of the misfits between observations and model predictions, which were based on the magnitudes of the minimum chi^2 and the mean of residuals fitting to a Gaussian function, indicate that the JGR2007 model gives

  3. PRESENT-DAY MASS FUNCTION OF SIX SMALL MAGELLANIC CLOUD INTERMEDIATE-AGE AND OLD STAR CLUSTERS

    SciTech Connect

    Glatt, Katharina; Grebel, Eva K.; Jordi, Katrin; Gallagher, John S. III; Harbeck, Daniel; Da Costa, Gary; Clementini, Gisella; Tosi, Monica; Nota, Antonella; Sabbi, Elena; Sirianni, Marco

    2011-08-15

    We determined the present-day mass functions (PDMFs) of the five intermediate-age star clusters Lindsay 1, Kron 3, NGC 339, NGC 416, and Lindsay 38 and the old star cluster NGC 121 in the Small Magellanic Cloud (SMC) based on observations with the Hubble Space Telescope Advanced Camera for Surveys. The global PDMFs are well matched by Salpeter-like power laws from their main-sequence turnoffs to {approx}0.6 M{sub sun} with a power-law exponent {alpha} ranging from 1.51 {+-} 0.11 (Lindsay 1) to 2.29 {+-} 0.15 (NGC 339). We derive total stellar masses of {approx}10{sup 5} M{sub sun}, except for Lindsay 38, whose mass is of the order of {approx}10{sup 4} M{sub sun}. Differences between the PDMFs most likely reflect the varying stages of dynamical evolution of the clusters. These SMC clusters do not follow the {alpha} versus concentration parameter c correlation as found for Galactic globular clusters of similar mass. This might be an age effect or due to their location in a galaxy where bulge and disk crossings do not play a role. No correlation is found between {alpha} and the cluster core and tidal radii (r{sub c} and r{sub t} , respectively), the half-light radii r{sub h} , age, central surface brightness, metallicity, and galactocentric radius r{sub gc}. All six clusters mass-segregated to different degrees. The two clusters Lindsay 1 and Kron 3 barely show signs for mass segregation, but have low-mass star deficient global PDMFs and might be the remnants of star clusters whose outer parts were stripped. A trend exists between the degree of mass segregation and the ratio age/relaxation time t{sub r,h}, which indicates the stage of dynamical evolution for a cluster. Our data thus suggest that the SMC clusters in the present sample had a range of initial densities and presumably different amounts of mass loss that led to different rates of dynamical evolution. The clusters' positions in the r{sub h,m}/r{sub t} versus r{sub 0}/r{sub h,m} plane imply that all of the

  4. Hazard responses in the pre-industrial era: vulnerability and resilience of traditional societies to volcanic disasters and the implications for present-day disaster planning

    NASA Astrophysics Data System (ADS)

    Sangster, Heather

    2014-05-01

    A major research frontier in the study of natural hazard research involves unravelling the ways in which societies have reacted historically to disasters, and how such responses influence current policies of disaster reduction. For societies it is common to classify responses to natural hazards into: pre-industrial (folk); industrial; and post-industrial (comprehensive) responses. Pre-industrial societies are characterised by: a pre-dominantly rural location; an agricultural economic focus; artisan handicrafts rather than industrial production, parochialism, with people rarely travelling outside their local area and being little affected by external events and a feudal or semi-feudal social structure. In the past, hazard assessment focused on the physical processes that produced extreme and potentially damaging occurrences, however from the middle of the twenty-first century research into natural hazards has been cast within a framework defined by the polarities (or opposites) of vulnerability and resilience, subject to a blend of unique environmental, social, economic and cultural forces in hazardous areas, that either increase or decrease the impact of extreme events on a given society. In the past decade research of this type has been facilitated by a 'revolution' of source materials across a range of languages and in a variety of electronic formats (e.g. official archives; major contemporary and near-contemporary publications - often available as reprints; national and international newspapers of record; newsreel-films; and, photographs) and in the introduction of more reliable translation software (e.g. Systrans) that provides far more scope to the researcher in the study of natural hazards than was the case even a few years ago. Knowledge of hazard responses in the pre-industrial era is, not only important in its own right because it reveals indigenous strategies of coping, but also informs present-day disaster planners about how people have reacted to past

  5. Present-day submarine hydrothermal activity in the Taupo-Rotorua Zone (Bay of Plenty, New Zealand)

    SciTech Connect

    Osipenko, A.B.; Egorov, Yu.O.; Fazlullin, S.M.; Gavrilenko, G.M.; Shul`kin, V.I.; Chertkova, L.V.

    1994-09-01

    We made detailed descriptions of the structure and material composition of sedimentary and water columns in the vicinity of active submarine hydrothermal activity in the southern part of the Bay of Plenty (North Island, New Zealand). Geophysical methods revealed that the hydrothermal system is confined to a tectonically distinct zone with a sedimentary cover characterized by complex structure. Chemical and mineralogical investigations confirmed that the activity of underwater vents exerts no substantial regional influence on the composition and features of ore mineralization in these formations. It is shown that essentially hydrothermal formations distinguishable within areas of otherwise monotypic sediments directly coincide with zones of hydrothermal discharge in the ocean floor. The absence of pronounced hydrothermal anomalies, together with the presence of {open_quotes}tongues{close_quotes} of anomalous concentrations of water-soluble gases suggests that the discharges are primarily hydrothermal in character.

  6. From past sailors' eras to the present day: scurvy as a surprising manifestation of an uncommon gastrointestinal disease.

    PubMed

    Branquinho, Diogo Ferreira; Pinto-Gouveia, Miguel; Mendes, Sofia; Sofia, Carlos

    2015-01-01

    A 45-year-old man presented with follicular exanthema in his lower limbs, alternating bowel habits and significant weight loss. His medical history included seronegative arthritis, bipolar disease and an inconclusive diagnostic laparoscopy. Diagnostic work up revealed microcytic anaemia and multivitamin deficiency. Skin biopsy of the exanthema suggested scurvy. Owing to these signs of malabsorption, upper endoscopy with duodenal biopsies was performed, exhibiting villous atrophy and extensive periodic acid-Schiff-positive material in the lamina propria, therefore diagnosing Whipple's disease (WD). After starting treatment with ceftriaxone and co-trimoxazole, an impressive recovery was noted, as the wide spectrum of malabsorption signs quickly disappeared. After a year of antibiotics, articular and cutaneous manifestations improved, allowing the patient to stop taking corticosteroids and antidepressants. This truly unusual presentation reflects the multisystemic nature of WD, often leading to misdiagnosis of other entities. Scurvy is a rare finding in developed countries, but its presence should raise suspicion for small bowel disease. PMID:26376699

  7. Present-day Galaxy Evolution through Baryon Flows in the Circumgalactic Medium of the Galactic-Magellanic System

    NASA Astrophysics Data System (ADS)

    Barger, Kathleen Ann

    Galaxy evolution is governed by an intricate ballet of gas flows. To sustain star formation over many billions of years, more gas must inflow than outflow. Although numerous gas clouds surround the Milky Way, their attributes, origins, destinations, and responses to their surroundings need thorough investigation on an individual basis to realize how the entire population affects Galactic evolution. This dissertation hones in on two circumgalactic gas structures near the Milky Way: Complex A and the Magellanic Bridge. Complex A is an elongated gas structure that is traversing the hot Halo of the Milky Way, plummeting towards the Galaxy's disk. The Magellanic Bridge is a bridge of gas and stars that connects the Magellanic Clouds, created by galaxy interactions. In this thesis, I present the results of the highest sensitivity and kinematically resolved Halpha emission-line survey of Complex A and Halpha, [S II], and [N II] surveys of the Magellanic Bridge using the Wisconsin Halpha Mapper to explore their properties, surroundings, origins, and fates to unravel how circumgalactic structures influence galaxy evolution. I find that the observational properties of Complex A closely match with radiative transfer model predictions of a cloud ionized by the Milky Way and extragalactic background, implying a 5% escape fraction of ionizing photons from the Galactic disk. The multiline observations and modeling place the cloud's metallicity below solar. These results combined with other studies suggests the cloud has an intergalactic medium origin. I find that the global distribution of the warm ionized gas traces the neutral gas in the Magellanic Bridge. These observations place the ionized gas mass between (0.7 -- 1.6) x 108 solar masses, implying an ionization fraction of 25 -- 33% and a 5% maximum escape fraction of ionizing photons from the Magellanic Clouds. The line ratios reveal that the physical state of the the SMC-Tail and the LMC-Bridge interface regions differ

  8. Intraseasonal Variability of the South Asian Summer Monsoon: Present-day Simulations with the Regional Atmospheric Model HIRHAM5

    NASA Astrophysics Data System (ADS)

    Hanf, F. S.; Rinke, A.; Dethloff, K.

    2014-12-01

    Since 1950, observations show a robust negative trend of the seasonal rainfall associated with the South Asian summer monsoon over India coinciding with a continuous decrease in surface solar radiation ("dimming") over South Asia due to an increase of local aerosol emissions. On the intraseasonal timescale the summer monsoon fluctuates between periods of enhanced and reduced rainfall. The frequency of occurrence of these active and breaks monsoon phases affects directly the seasonal monsoon rainfall. This study investigates the regional pattern and changes of the South Asian monsoon for the period 1979-2012 using the regional atmospheric model HIRHAM5 with a horizontal resolution of 0.25° forced at the lateral and lower boundaries with ERA-Interim reanalysis data. Despite the dry bias in the mean summer monsoon rainfall over the Indian landmass, the simulated temperature and atmospheric circulation patterns are in agreement with the ERA-Interim reanalysis indicating a realistic representation of important dynamical summer monsoon features. In addition, mechanisms which controls active and break phases within the summer monsoon season are analyzed using daily outgoing longwave radiation model data as an identification tool of monsoon breaks as proposed by Krishnan et al. (2000). Model results reveal an increasing trend of the cumulative monsoon break days of around 1.4 days per year during the last 30 years. The possible link between this increasing of cumulative monsoon break days and the observed decrease of seasonal South Asian monsoon rainfall will be the scope of further investigations.

  9. The impact of modern migrations on present-day multi-ethnic Argentina as recorded on the mitochondrial DNA genome

    PubMed Central

    2011-01-01

    Background The genetic background of Argentineans is a mosaic of different continental ancestries. From colonial to present times, the genetic contribution of Europeans and sub-Saharan Africans has superposed to or replaced the indigenous genetic 'stratum'. A sample of 384 individuals representing different Argentinean provinces was collected and genotyped for the first and the second mitochondrial DNA (mtDNA) hypervariable regions, and selectively genotyped for mtDNA SNPs. This data was analyzed together with additional 440 profiles from rural and urban populations plus 304 from Native American Argentineans, all available from the literature. A worldwide database was used for phylogeographic inferences, inter-population comparisons, and admixture analysis. Samples identified as belonging to hg (hg) H2a5 were sequenced for the entire mtDNA genome. Results Phylogenetic and admixture analyses indicate that only half of the Native American component in urban Argentineans might be attributed to the legacy of extinct ancestral Argentineans and that the Spanish genetic contribution is slightly higher than the Italian one. Entire H2a5 genomes linked these Argentinean mtDNAs to the Basque Country and improved the phylogeny of this Basque autochthonous clade. The fingerprint of African slaves in urban Argentinean mtDNAs was low and it can be phylogeographically attributed predominantly to western African. The European component is significantly more prevalent in the Buenos Aires province, the main gate of entrance for Atlantic immigration to Argentina, while the Native American component is larger in North and South Argentina. AMOVA, Principal Component Analysis and hgs/haplotype patterns in Argentina revealed an important level of genetic sub-structure in the country. Conclusions Studies aimed to compare mtDNA frequency profiles from different Argentinean geographical regions (e.g., forensic and case-control studies) should take into account the important genetic

  10. Growth changes in plaice, cod, haddock and saithe in the North Sea: a comparison of (post-)medieval and present-day growth rates based on otolith measurements

    NASA Astrophysics Data System (ADS)

    Bolle, Loes J.; Rijnsdorp, Adriaan D.; van Neer, Wim; Millner, Richard S.; van Leeuwen, Piet I.; Ervynck, Anton; Ayers, Richard; Ongenae, Ellen

    2004-05-01

    Fishing effort has strongly increased in the North Sea since the mid-19th century, causing a substantial reduction in the population size of exploited fish stocks. As fisheries research has developed simultaneously with the industrialisation of the fisheries, our knowledge of population dynamics at low levels of exploitations is limited. Otoliths retrieved from archaeological excavations offer a unique opportunity to study growth rates in the past. This study compares historical and present-day growth rates for four commercially important demersal fish species. A total of 2532 modern otoliths (AD 1984-1999) and 1286 historical otoliths (AD 1200-1925) obtained from archaeological excavations in Belgium and Scotland were analysed. Comparison of the growth patterns between eras revealed a major increase in growth rate of haddock, whereas growth changes were not observed in saithe and only in the smaller size classes of plaice and cod. Comparison of our results with literature data indicates that the observed growth rate changes in plaice and cod occurred within the 20th century. Apparently the onset of industrialised fisheries has not greatly affected the growth of plaice, cod and saithe populations in the North Sea. This result contradicts the expectation of density-dependent limitation of growth during the era of pre-industrialised fishing, but is in agreement with the concentration hypothesis of Beverton (Neth. J. Sea Res. 34 (1995) 1) stating that species which concentrate spatially into nursery grounds during their early life-history may 'saturate' the carrying capacity of the juvenile habitat even though the adult part of the population is not limited by the adult habitat.

  11. Historic, pre-European settlement, and present-day contribution of wild ruminants to enteric methane emissions in the United States.

    PubMed

    Hristov, A N

    2012-04-01

    The objectives of this analysis were to estimate historic (pre-European settlement) enteric CH(4) emissions from wild ruminants in the contiguous United States and compare these with present-day CH(4) emissions from farmed ruminants. The analysis included bison, elk (wapiti), and deer (white-tailed and mule). Wild ruminants such as moose, antelope (pronghorn), caribou, and mountain sheep and goat were not included in the analysis because their natural range is mostly outside the contiguous United States or because they have relatively small population sizes. Data for presettlement and present-day population sizes, animal BW, feed intake, and CH(4) emission factors were adopted from various sources. Present-day CH(4) emissions from livestock were from recent United States Environmental Protection Agency estimates. The most important factor determining CH(4) emissions from wild ruminants in the presettlement period was the size of the bison population. Overall, enteric CH(4) emissions from bison, elk, and deer in the presettlement period were about 86% (assuming bison population size of 50 million) of the current CH(4) emissions from farmed ruminants in the United States. Present-day CH(4) emissions from wild ruminants (bison, elk, and deer) were estimated at 0.28 Tg/yr, or 4.3% of the emissions from domestic ruminants. Due to its population size (estimated at 25 million), the white-tailed deer is the most significant present-day wild ruminant contributor to enteric CH(4) emissions in the contiguous United States. PMID:22178852

  12. Present-day plate motions

    NASA Technical Reports Server (NTRS)

    Minster, J. B.; Jordan, T. H.

    1977-01-01

    A data set comprising 110 spreading rates, 78 transform fault azimuths and 142 earthquake slip vectors was inverted to yield a new instantaneous plate motion model, designated RM2. The mean averaging interval for the relative motion data was reduced to less than 3 My. A detailed comparison of RM2 with angular velocity vectors which best fit the data along individual plate boundaries indicates that RM2 performs close to optimally in most regions, with several notable exceptions. On the other hand, a previous estimate (RM1) failed to satisfy an extensive set of new data collected in the South Atlantic Ocean. It is shown that RM1 incorrectly predicts the plate kinematics in the South Atlantic because the presently available data are inconsistent with the plate geometry assumed in deriving RM1. It is demonstrated that this inconsistency can be remedied by postulating the existence of internal deformation with the Indian plate, although alternate explanations are possible.

  13. Estimations of historical atmospheric mercury concentrations from mercury refining and present-day soil concentrations of total mercury in Huancavelica, Peru.

    PubMed

    Robins, Nicholas A; Hagan, Nicole; Halabi, Susan; Hsu-Kim, Heileen; Gonzales, Ruben Dario Espinoza; Morris, Mark; Woodall, George; Richter, Daniel deB; Heine, Paul; Zhang, Tong; Bacon, Allan; Vandenberg, John

    2012-06-01

    Detailed Spanish records of cinnabar mining and mercury production during the colonial period in Huancavelica, Peru were examined to estimate historical health risks to the community from exposure to elemental mercury (Hg) vapor resulting from cinnabar refining operations. Between 1564 and 1810, nearly 17,000 metric tons of Hg were released to the atmosphere in Huancavelica from Hg production. AERMOD was used with estimated emissions and source characteristics to approximate historic atmospheric concentrations of mercury vapor. Modeled 1-hour and long-term concentrations were compared with present-day inhalation reference values for elemental Hg. Estimated 1-hour maximum concentrations for the entire community exceeded present-day occupational inhalation reference values, while some areas closest to the smelters exceeded present-day emergency response guideline levels. Estimated long-term maximum concentrations for the entire community exceeded the EPA Reference Concentration (RfC) by a factor of 30 to 100, with areas closest to the smelters exceeding the RfC by a factor of 300 to 1000. Based on the estimated historical concentrations of Hg vapor in the community, the study also measured the extent of present-day contamination throughout the community through soil sampling and analysis. Total Hg in soils sampled from 20 locations ranged from 1.75 to 698 mg/kg and three adobe brick samples ranging from 47.4 to 284 mg/kg, consistent with other sites of mercury mining and use. The results of the soil sampling indicate that the present-day population of Huancavelica is exposed to levels of mercury from legacy contamination which is currently among the highest worldwide, consequently placing them at potential risk of adverse health outcomes. PMID:22542225

  14. Post World War II orcharding creates present day DDT-problems in The Sørfjord (Western Norway)--a case study.

    PubMed

    Ruus, Anders; Green, Norman W; Maage, Amund; Amundsen, Carl Einar; Schøyen, Merete; Skei, Jens

    2010-10-01

    The Sørfjord has a long history of agriculture and industry, and environmental monitoring has been conducted for decades, comprising analyses of contaminants in mussel, fish and sediments. DDT was used as an insecticide in orchards surrounding the fjord between World War II and 1970. Since the early 1990 s, elevated concentrations of DDT were found in mussels and fish. Unexpectedly, DDT-concentrations increased towards present day, despite the discontinuation of use. The highest concentrations in mussels (in 2006) corresponded to about two orders of magnitude higher than background. Analyses of sediment core sections also indicated increased input towards present day. Shifts in climatic parameters, as well as increased amounts of soil dissolved organic carbon following a decline in atmospheric sulphate deposition may have contributed to this phenomenon. We warrant the need for increased knowledge of the effects of alterations in variables acting regionally and globally on the disposition of contaminants in ecosystems. PMID:20719343

  15. The influence of mantle viscosity structure and past decadal to millennial-scale ice mass changes on present-day land motion in Greenland.

    NASA Astrophysics Data System (ADS)

    Simpson, Matthew; Wake, Leanne; Milne, Glenn; Huybrechts, Philippe

    2010-05-01

    We show predictions of present-day vertical land motion in Greenland using a recently developed Glacial Isostatic Adjustment (GIA) model, calibrated using both relative sea-level observations and geomorphological contraints on ice extent (Simpson et al., 2009). Predictions from our GIA model are in good agreement to the relatively small number of GPS measurements of absolute vertical motion from south and southwest Greenland. This suggests that our model of ice sheet evolution over the Holocene period is reasonably accurate. The uplift predictions are highly sensitive to variations of upper mantle viscosity; depending on the Earth model adopted different periods of ice loading change dominate the present-day response in particular regions of Greenland. We shall present a suite of results to demonstrate this sensitivity. We also consider the possible influence of more recent changes in the ice sheet by applying a second ice model; specifically, a surface mass balance (SMB) model (Wake et al., 2009), which covers the period 1866 to 2005. Predictions from this model suggest that decadal-scale SMB changes over the last c. 140 years play only a small role in determining the present-day viscous response. However, high rates of peripheral thinning from 1995 to 2005 in the SMB model produce large elastic uplift rates in west and southwest Greenland. Using the same SMB model, we extend our study period to cover the last thousand years (for which there is less accurate climate data) and constrain ice mass changes over this time using new high resolution records of relative sea-level change. Our preliminary findings suggest that century-scale ice mass variation over the last thousand years may contribute significantly to the present-day viscous response. Simpson, M.J.R, Milne, G.A., Huybrechts, P., Long, A.J., 2009. Calibrating a glaciological model of the Greenland ice sheet from the last glacial maximum to present-day using field observations of relative sea level and ice

  16. Lyα-emitting Galaxies at z = 2.1 in ECDF-S: Building Blocks of Typical Present-day Galaxies?

    NASA Astrophysics Data System (ADS)

    Guaita, Lucia; Gawiser, Eric; Padilla, Nelson; Francke, Harold; Bond, Nicholas A.; Gronwall, Caryl; Ciardullo, Robin; Feldmeier, John J.; Sinawa, Shawn; Blanc, Guillermo A.; Virani, Shanil

    2010-05-01

    ) = 11.5+0.4 -0.5, which are among the lowest mass halos yet probed at this redshift. We used the Sheth and Tormen conditional mass function to study the descendants of these LAEs and found that their typical present-day descendants are local galaxies with L* properties, like the Milky Way. Based on observations obtained at Cerro Tololo Inter-American Observatory, a division of the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

  17. Preindustrial to Present-Day Changes in Tropospheric Hydroxyl Radical and Methane Lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Naik, V.; Voulgarakis, A.; Fiore, A. M.; Horowitz, L. W.; Lamarque, J.-F.; Lin, M.; Prather, M. J.; Young, P. J.; Bergmann, D.; Cameron-Smith, P. J.; Cionni, I.; Collins, W. J.; Dalsoren, S. B.; Doherty, R.; Eyring, V.; Faluvegi, G.; Folberth, G. A.; Josse, B.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.; vanNoije, T. P. C.; Plummer, D. A.; Righi, M.; Rumbold, S. T.; Skeie, R.; Shindell, D. T.; Stevenson, D. S.; Strode, S.; Sudo, K.; Szopa, S.; Zeng, G.

    2013-01-01

    We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multi-model mean OH concentration is overestimated by 5 to 10% but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north–south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34%). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7% to an increase of 14.6%) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the

  18. Estimating heat stress from climate-based indicators: present-day biases and future spreads in the CMIP5 global climate model ensemble

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Ducharne, A.; Sultan, B.; Braconnot, P.; Vautard, R.

    2015-08-01

    The increased exposure of human populations to heat stress is one of the likely consequences of global warming, and it has detrimental effects on health and labor capacity. Here, we consider the evolution of heat stress under climate change using 21 general circulation models (GCMs). Three heat stress indicators, based on both temperature and humidity conditions, are used to investigate present-day model biases and spreads in future climate projections. Present day estimates of heat stress indicators from observational data shows that humid tropical areas tend to experience more frequent heat stress than other regions do, with a total frequency of heat stress 250-300 d yr-1. The most severe heat stress is found in the Sahel and south India. Present-day GCM simulations tend to underestimate heat stress over the tropics due to dry and cold model biases. The model based estimates are in better agreement with observation in mid to high latitudes, but this is due to compensating errors in humidity and temperature. The severity of heat stress is projected to increase by the end of the century under climate change scenario RCP8.5, reaching unprecedented levels in some regions compared with observations. An analysis of the different factors contributing to the total spread of projected heat stress shows that spread is primarily driven by the choice of GCMs rather than the choice of indicators, even when the simulated indicators are bias-corrected. This supports the utility of the multi-model ensemble approach to assess the impacts of climate change on heat stress.

  19. Structural Evolution of the India-Arabia Plate Boundary from Miocene to Present-Day (NW Indian Ocean) and Comparison with the Dead Sea Fault (Eastern Mediterranean Sea).

    NASA Astrophysics Data System (ADS)

    Rodriguez, M.; Huchon, P.; Chamot Rooke, N.; Fournier, M.; Delescluse, M.; Ben Avraham, Z.; Ten Brink, U. S.

    2014-12-01

    Arabia is bounded by the Dead Sea Transform (DST) to the west and by the Owen Fracture Zone (OFZ) to the east. These present-day major strike-slip fault systems activated during the Plio-Pleistocene, which contrasts with the age of inception of strike-slip motion, assumed to begin around 13-18 Ma for the DST and around 20 Ma at the edge of the Owen-Murray Ridge (OMR) for the India-Arabia plate boundary. This discrepancy between the age of the active strike-slip systems and the age of inception of strike-slip motion raises the question of the kinematic driver for the transition between successive generations of strike-slip faults. Using a recent mutibeam and seismic dataset crossing the OFZ and the OMR, we provide a new geodynamic framework for the Miocene to present-day structural evolution of the India-Arabia plate boundary, and highlight some similarities with the structural evolution of the DST. We first document a Late Miocene episode of uplift of the OMR uplift along the Miocene India-Arabia plate boundary. The onset of this uplift is coeval with a plate reorganization event marked by the onset of intra-plate deformation in the Central Indian Ocean. The OFZ emplaced around 3 Ma, with major pull-apart basins opening (20°N Basin, Dalrymple Trough) dated at 2.4 Ma by far-field correlation with ODP Sites. The opening of pull-apart basins is coeval with the last structural reorganization of the Makran accretionnary wedge, marked by the regional M-unconformity, and with a major intensification of the Indian monsoon. A Late Miocene episode of folding is also recognized at the Lebanon ranges prior to the onset of the present-day DST, which occurred in the Late Pliocene-Early Pleistocene. The similarities between the geological history of the India-Arabia plate boundary and the DST in the Late Miocene and the Late Pliocene-Early Pleistocene suggest that both plate boundaries recorded the same kinematic changes. Late Miocene (i.e. Tortonian) deformation is widely

  20. How significant are Phaeocystis colony blooms in the present-day Southern North Sea compared to a reconstructed pristine situation: a model study

    NASA Astrophysics Data System (ADS)

    Lancelot, Christiane; Passy, Paul; Gypens, Nathalie

    2014-05-01

    We performed simulations with the existing MIRO&CO 3D ecological model to assess the present-day magnitude and geographical extent of undesirable Phaeocystis colony blooms in the Southern Bight of the North Sea (SNS) receiving nutrient inputs by large European rivers. The criterion of 4 106 Phaeocystis cells L-1 of Lancelot et al. (2009) is used to scale the presence of undesirable bloom. These simulations are compared with a reconstructed pristine SNS ecosystem making use of nutrient inputs calculated by the Seneque/Riverstrahler model of the river system when all human activities on the watershed have been erased. Interannual variability is considered by performing model runs for two contrasted meteorological years: wet (2001) and dry (2005). Results show a large excess of nitrogen (N) and phosphorus (P) delivery to the SNS of i.e. respectively 12 and 5 times the pristine situation. In contrast the total silicon (Si) delivery is decreased with respect to natural conditions although not shown for every river. Qualitatively, pristine river inputs are shown a large excess Si for pristine but excess N for both 2001 and 2005, when compared to the agreed N, P and Si requirement of coastal diatoms. Responding to the river nutrient inputs, either natural or of anthropogenic origin, phytoplankton blooms are simulated in the vicinity of the river mouths, especially in the eastern SNS receiving 78-98% of the direct river inputs and where nutrients cumulate along a SW-NE gradient, allowing the bloom to form a wide ribbon parallel to the coast. A short time-delay is simulated between the western and eastern SNS due to light limitation imposed by the large sediment inputs discharged by the Thames. A spring diatom-Phaeocystis succession is simulated for both present-day and pristine. Pristine diatoms dominate the bulk of the phytoplankton community; Phaeocystis colonies develop in the whole domain, especially in the Thames and Scheldt river plume though their biomass remains

  1. The origin of the asymmetry in the Iceland hotspot along the Mid-Atlantic Ridge from continental breakup to present-day

    NASA Astrophysics Data System (ADS)

    Howell, Samuel M.; Ito, Garrett; Breivik, Asbjørn J.; Rai, Abhishek; Mjelde, Rolf; Hanan, Barry; Sayit, Kaan; Vogt, Peter

    2014-04-01

    The Iceland hotspot has profoundly influenced the creation of oceanic crust throughout the North Atlantic basin. Enigmatically, the geographic extent of the hotspot influence along the Mid-Atlantic Ridge has been asymmetric for most of the spreading history. This asymmetry is evident in crustal thickness along the present-day ridge system and anomalously shallow seafloor of ages ∼49-25 Ma created at the Reykjanes Ridge (RR), SSW of the hotspot center, compared to deeper seafloor created by the now-extinct Aegir Ridge (AR) the same distance NE of the hotspot center. The cause of this asymmetry is explored with 3-D numerical models that simulate a mantle plume interacting with the ridge system using realistic ridge geometries and spreading rates that evolve from continental breakup to present-day. The models predict plume-influence to be symmetric at continental breakup, then to rapidly contract along the ridges, resulting in widely influenced margins next to uninfluenced oceanic crust. After this initial stage, varying degrees of asymmetry along the mature ridge segments are predicted. Models in which the lithosphere is created by the stiffening of the mantle due to the extraction of water near the base of the melting zone predict a moderate amount of asymmetry; the plume expands NE along the AR ∼70-80% as far as it expands SSW along the RR. Without dehydration stiffening, the lithosphere corresponds to the near-surface, cool, thermal boundary layer; in these cases, the plume is predicted to be even more asymmetric, expanding only 40-50% as far along the AR as it does along the RR. Estimates of asymmetry and seismically measured crustal thicknesses are best explained by model predictions of an Iceland plume volume flux of ∼100-200 m/s, and a lithosphere controlled by a rheology in which dehydration stiffens the mantle, but to a lesser degree than simulated here. The asymmetry of influence along the present-day ridge system is predicted to be a transient

  2. Evaluating CMIP5 ocean biogeochemistry and Southern Ocean carbon uptake using atmospheric potential oxygen: Present-day performance and future projection

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Manizza, M.; Keeling, R. F.; Stephens, B. B.; Bent, J. D.; Dunne, J.; Ilyina, T.; Long, M.; Resplandy, L.; Tjiputra, J.; Yukimoto, S.

    2016-03-01

    Observed seasonal cycles in atmospheric potential oxygen (APO ~ O2 + 1.1 CO2) were used to evaluate eight ocean biogeochemistry models from the Coupled Model Intercomparison Project (CMIP5). Model APO seasonal cycles were computed from the CMIP5 air-sea O2 and CO2 fluxes and compared to observations at three Southern Hemisphere monitoring sites. Four of the models captured either the observed APO seasonal amplitude or phasing relatively well, while the other four did not. Many models had an unrealistic seasonal phasing or amplitude of the CO2 flux, which in turn influenced APO. By 2100 under RCP8.5, the models projected little change in the O2 component of APO but large changes in the seasonality of the CO2 component associated with ocean acidification. The models with poorer performance on present-day APO tended to project larger net carbon uptake in the Southern Ocean, both today and in 2100.

  3. Seismological Structure of the 1.8Ga Trans-Hudson Orogen of North America and its affinity to present-day Tibet

    NASA Astrophysics Data System (ADS)

    Gilligan, A.; Bastow, I. D.; Darbyshire, F. A.

    2015-12-01

    How tectonic processes operated and changed through the Precambrian is debated: what was the nature and scale of orogenic events and were they different on the younger, hotter, more ductile Earth? The geology of northern Hudson Bay records the Paleoproterozoic collision between the Western Churchill and Superior plates: the 1.8Ga Trans-Hudson Orogeny (THO) and is thus an ideal study locale to address this issue. It has been suggested, primarily on the strength of traditional field geology, that the THO was comparable in scale and style to the present-day Himalayan-Karakoram-Tibet Orogen (HKTO). However, understanding of the deep crustal architecture of the THO, and how it compares to the evolving HKTO is presently lacking. Through joint inversion of teleseismic receiver functions and surface wave data, we obtain new Moho depth estimates and shear velocity models for the crust and upper mantle. Archean crust in the Rae, Hearne and Churchill domains is thin and structurally simple, with a sharp Moho; upper crustal wavespeed variations are readily attributed to post-formation events. However, the Paleoproterozoic Quebec-Baffin segment of the THO has a deeper Moho and more complex crustal structure. Our observations are strikingly similar to recent models, computed using the same methods, of the HKTO lithosphere, where deformation also extends >400km beyond the collision front. On the strength of Moho character, present-day crustal thickness, and metamorphic grade, we thus propose that southern Baffin experienced uplift of a similar magnitude and spatial extent to the Himalayas during the Paleoproterozoic Trans-Hudson Orogeny.

  4. Quantitative Study of the Present-Day Climate of the Middle Tennessee Elk Watershed Area From Global and Regional Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Kebede, G.

    2015-12-01

    As part of a wider hydro climatic modeling research, we studied the spatial and temporal variability of precipitation and temperature over the Middle Tennessee Elk watershed and its environs using regional climate model simulations over the past 30 years. Three sets of simulations with the Hadley Center's regional climate model (PRECIS) were carried out for the present day climate (1980-2010) at a resolution of 25km covering the southeastern U.S. These three sets simulations are driven by lateral boundary conditions taken from ERA-Interim reanalysis, and two global climate models (HadCM3 and ECHAM5) respectively. For validation, high resolution observed daily data sets from North American Land-Data Assimilation System (NLDAS) and Climate Research Unit, CRU data are used. Preliminary results show that the spatial distribution of the present-day seasonal mean rainfall and temperature, simulated by PRECIS, are not only consistent with NLDAS and CRU but also captured fine scale spatial structures that are missing in the global model simulations due to their coarse resolution. In addition, the annual cycle and intera-anual variability, particularly that of temperature, are reasonably well reproduced by the PRECIS. When comparing the PRECIS simulations with the driving GCMs, PRECIS is sensitive to the choice of the driving GCM, suggesting a careful selection of driving GCM based on the current climate performance for the use of future climate impact assessment. Quantitative understanding of the climate system and better estimation of the fresh water balance over the Middle Tennessee Elk watershed is a vital corner stone for a sustainable economic growth of the region over the coming decades.

  5. Estimating historical atmospheric mercury concentrations from silver mining and their legacies in present-day surface soil in Potosí, Bolivia

    NASA Astrophysics Data System (ADS)

    Hagan, Nicole; Robins, Nicholas; Hsu-Kim, Heileen; Halabi, Susan; Morris, Mark; Woodall, George; Zhang, Tong; Bacon, Allan; Richter, Daniel De B.; Vandenberg, John

    2011-12-01

    Detailed Spanish records of mercury use and silver production during the colonial period in Potosí, Bolivia were evaluated to estimate atmospheric emissions of mercury from silver smelting. Mercury was used in the silver production process in Potosí and nearly 32,000 metric tons of mercury were released to the environment. AERMOD was used in combination with the estimated emissions to approximate historical air concentrations of mercury from colonial mining operations during 1715, a year of relatively low silver production. Source characteristics were selected from archival documents, colonial maps and images of silver smelters in Potosí and a base case of input parameters was selected. Input parameters were varied to understand the sensitivity of the model to each parameter. Modeled maximum 1-h concentrations were most sensitive to stack height and diameter, whereas an index of community exposure was relatively insensitive to uncertainty in input parameters. Modeled 1-h and long-term concentrations were compared to inhalation reference values for elemental mercury vapor. Estimated 1-h maximum concentrations within 500 m of the silver smelters consistently exceeded present-day occupational inhalation reference values. Additionally, the entire community was estimated to have been exposed to levels of mercury vapor that exceed present-day acute inhalation reference values for the general public. Estimated long-term maximum concentrations of mercury were predicted to substantially exceed the EPA Reference Concentration for areas within 600 m of the silver smelters. A concentration gradient predicted by AERMOD was used to select soil sampling locations along transects in Potosí. Total mercury in soils ranged from 0.105 to 155 mg kg-1, among the highest levels reported for surface soils in the scientific literature. The correlation between estimated air concentrations and measured soil concentrations will guide future research to determine the extent to which the

  6. The Impact of LEP G-2548A and LEPR Gln223Arg Polymorphisms on Adiposity, Leptin, and Leptin-Receptor Serum Levels in a Mexican Mestizo Population

    PubMed Central

    Chavarria-Avila, Efraín; Gomez-Bañuelos, Eduardo; Ruiz-Quezada, Sandra-Luz; Castro-Albarran, Jorge; Sánchez-López, Lizeth; Martín-Marquez, Beatriz Teresita; Navarro-Hernández, Rosa-Elena

    2015-01-01

    The polymorphisms in leptin (LEP G-2548A) and leptin-receptor (LEPR Gln223Arg) seem to influence obesity and lipid metabolism among others. The aim of this study was to investigate the effect of these polymorphisms on adiposity, leptin (sLeptin), and leptin-receptor (sLeptin-receptor) serum concentrations as well as inflammation markers. We included 382 adults originally from Western Mexico. They were genotyped by PCR-RFLP. Obese individuals showed higher sLeptin (58.2 ± 31.35 ng/mL) but lower sLeptin-receptor (12.6 ± 3.74 ng/mL) levels than normal weight ones (17.6 ± 14.62 ng/mL, 17.4 ± 4.62 ng/mL, resp.), P < 0.001. Obese subjects carriers of Arg/Arg genotype had more (P = 0.016) sLeptin-receptor (14.7 ± 4.96 ng/mL) and less (P = 0.004) sLeptin (44.0 ± 28.12 ng/mL) levels than Gln/Gln genotype (11.0 ± 2.92 ng/mL, 80.3 ± 33.24 ng/mL, resp.). Body fat mass was lower (P from 0.003 to 0.045) for A/A (36.5% ± 6.80) or Arg/Arg (36.8% ± 6.82) genotypes with respect to G/G (41.3% ± 5.52) and G/A (41.6% ± 5.61) or Gln/Gln (43.7% ± 4.74) and Gln/Arg (41.0% ± 5.52) genotypes carriers. Our results suggest that LEP -2548A and LEPR 223Arg could be genetic markers of less body fat mass accumulation in obese subjects from Western Mexico. PMID:26064921

  7. Population data of 24 STRs in Mexican-Mestizo population from Monterrey, Nuevo Leon (Northeast, Mexico) based on Powerplex(®) Fusion and GlobalFiler(®) kits.

    PubMed

    Ramos-González, Benito; Aguilar-Velázquez, José Alonso; Chávez-Briones, María de Lourdes; Delgado-Chavarría, Juan Ramón; Alfaro-Lopez, Elizabeth; Rangel-Villalobos, Héctor

    2016-03-01

    The STR loci included into new commercial human identification kits compels geneticists estimating forensic parameters for interpretation purposes in forensic casework. Therefore, we studied for the first time in Mexico the GlobalFiler(®) and Powerplex(®) Fusion systems in 326 and 682 unrelated individuals, respectively. These individuals are resident of the Monterrey City of the Nuevo Leon state (Northeast, Mexico). Population data from 23 autosomal STRs and the Y-STR locus DYS391 are reported and compared against available STR data from American ethnic groups and the unique Mexican population studied with Powerplex(®) Fusion. PMID:26747399

  8. Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models

    NASA Astrophysics Data System (ADS)

    Nieva, M.-F.; Przybilla, N.

    2012-03-01

    Context. Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstellar medium (ISM) or H ii regions. Aims: A carefully selected sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Quantitative spectroscopy is used to characterise their atmospheric properties in a self-consistent way. Present-day abundances for the astrophysically most interesting chemical elements are derived in order to investigate whether a present-day cosmic abundance standard can be established. Methods: High-resolution and high-S/N FOCES, FEROS and ELODIE spectra of well-studied sharp-lined early B-type stars are analysed in non-LTE. Line-profile fits based on extensive model grids and an iterative analysis methodology are used to constrain stellar parameters and elemental abundances at high accuracy and precision. Atmospheric parameters are derived from the simultaneous establishment of independent indicators, from multiple ionization equilibria and the Stark-broadened hydrogen Balmer lines, and they are confirmed by reproduction of the stars' global spectral energy distributions. Results: Effective temperatures are constrained to 1-2% and surface gravities to less than 15% uncertainty, along with accurate rotational, micro- and macroturbulence velocities. Good agreement of the resulting spectroscopic parallaxes with those from the new reduction of the Hipparcos catalogue is obtained. Absolute values for abundances of He, C, N, O, Ne, Mg, Si and Fe are determined to better than 25% uncertainty. The synthetic spectra match the observations reliably over almost the entire visual spectral range. Three sample stars, γ Ori, o Per and θ1 Ori D, are

  9. Differential responses of calcifying and non-calcifying epibionts of a brown macroalga to present-day and future upwelling pCO2.

    PubMed

    Saderne, Vincent; Wahl, Martin

    2013-01-01

    Seaweeds are key species of the Baltic Sea benthic ecosystems. They are the substratum of numerous fouling epibionts like bryozoans and tubeworms. Several of these epibionts bear calcified structures and could be impacted by the high pCO2 events of the late summer upwellings in the Baltic nearshores. Those events are expected to increase in strength and duration with global change and ocean acidification. If calcifying epibionts are impacted by transient acidification as driven by upwelling events, their increasing prevalence could cause a shift of the fouling communities toward fleshy species. The aim of the present study was to test the sensitivity of selected seaweed macrofoulers to transient elevation of pCO2 in their natural microenvironment, i.e. the boundary layer covering the thallus surface of brown seaweeds. Fragments of the macroalga Fucus serratus bearing an epibiotic community composed of the calcifiers Spirorbis spirorbis (Annelida) and Electra pilosa (Bryozoa) and the non-calcifier Alcyonidium hirsutum (Bryozoa) were maintained for 30 days under three pCO2 conditions: natural 460 ± 59 µatm, present-day upwelling1193 ± 166 µatm and future upwelling 3150 ± 446 µatm. Only the highest pCO2 caused a significant reduction of growth rates and settlement of S. spirorbis individuals. Additionally, S. spirorbis settled juveniles exhibited enhanced calcification of 40% during daylight hours compared to dark hours, possibly reflecting a day-night alternation of an acidification-modulating effect by algal photosynthesis as opposed to an acidification-enhancing effect of algal respiration. E. pilosa colonies showed significantly increased growth rates at intermediate pCO2 (1193 µatm) but no response to higher pCO2. No effect of acidification on A. hirsutum colonies growth rates was observed. The results suggest a remarkable resistance of the algal macro-epibionts to levels of acidification occurring at present day upwellings in the Baltic. Only extreme

  10. Human responses to eruptions of Etna (Sicily) during the late-Pre-Industrial Era and their implications for present-day disaster planning

    NASA Astrophysics Data System (ADS)

    Chester, David K.; Duncan, Angus M.; Sangster, Heather

    2012-05-01

    This paper summarises: the characteristics of eruptions that occurred between 1792/3 and 1923; the ways in which human responses evolved during the period and the lessons this history holds for the management of present-day volcanic and volcano-related disasters. People responded to eruptions at three levels: as members of a family and extended family; through the mutual support of a village or larger settlement and as citizens of the State. During the study period and with the exception of limited financial aid and preservation of law and order, the State was a minor player in responding to eruptions. Families and extended families provided shelter, accommodation and often alternative agricultural employment; whilst supportive villages communities displayed a well developed tendency to learn from experience (e.g. innovating techniques to bring land back into cultivation and avoiding the risks of phreatic activity as lava encountered water and saturated ground) and providing labour to enable household chattels and agricultural crops to be salvaged from land threatened with lava incursion. Eruptions were widely believed to be 'Acts of God', with divine punishment frequently being invoked as a primary cause of human suffering. Elaborate rituals of propitiation were performed to appease a supposed angry God, but this world-view did not produce a fatalistic attitude amongst the population preventing people from coping with disasters in a generally effective manner. Despite present day emergencies being handled by the State and its agencies, some features of nineteenth century responses remain in evidence, including salvaging all that may be easily removed from a building and/or agricultural holding, and explanations of disaster which are theistic in character. Lessons from eruptions that occurred between 1792/3 to 1923 are that the former should be encouraged, whilst the latter does not prevent people acting to preserve life and property or obeying the authorities

  11. UV-B absorbing compounds in present-day and fossil pollen, spores, cuticles, seed coats and wood: evaluation of a proxy for solar UV radiation.

    PubMed

    Rozema, J; Blokker, P; Mayoral Fuertes, M A; Broekman, R

    2009-09-01

    UV-B absorbing compounds (UACs) in present-day and fossil pollen, spores, cuticles, seed coats and wood have been evaluated as a proxy for past UV. This proxy may not only provide information on variation of stratospheric ozone and solar UV in the period preceding and during the Antarctic ozone hole (1974-present day), but also on the development and variation of the stratospheric ozone layer and solar surface UV during the evolution of life on Earth. Sporopollenin and cutin are highly resistant biopolymers, preserving well in the geological record and contain the phenolic acids p-coumaric (pCA) and ferulic acid (FA). pCA and FA represent a good perspective for a plant-based proxy for past surface UV radiation since they are induced by solar UV-B via the phenylpropanoid pathway (PPP). UV-B absorption by these monomers in the wall of pollen and spores and in cuticles may prevent damage to the cellular metabolism. Increased pCA and FA in pollen of Vicia faba exposed to enhanced UV-B was found in greenhouse experiments. Further correlative evidence comes from UV-absorbing compounds in spores from 1960-2000 comparing exposure of land plants (Lycopodium species) to solar UV before and during ozone depletion and comparing plants from Antarctica (severe ozone depletion), Arctic, and other latitudes with less or negligible ozone depletion. Wood-derived compounds guaiacyl (G), syringyl (S), and p-hydroxyphenyl (P) are produced via the PPP. The proportions of P, G, and S in the lignin differ between various plant groups (e.g. dicotyledons/monocotyledons, gymnosperms/angiosperms). It is hypothesized that this lignin composition and derived physiological and physical properties of lignin (such as tree-ring wood density) has potential as a proxy for palaeo-UV climate. However validation by exposure of trees to enhanced UV is lacking. pCA and FA also form part of cutin polymers and are found in extant and fossil Ginkgo leaf cuticles as shown by thermally-assisted hydrolysis and

  12. Differential Responses of Calcifying and Non-Calcifying Epibionts of a Brown Macroalga to Present-Day and Future Upwelling pCO2

    PubMed Central

    Saderne, Vincent; Wahl, Martin

    2013-01-01

    Seaweeds are key species of the Baltic Sea benthic ecosystems. They are the substratum of numerous fouling epibionts like bryozoans and tubeworms. Several of these epibionts bear calcified structures and could be impacted by the high pCO2 events of the late summer upwellings in the Baltic nearshores. Those events are expected to increase in strength and duration with global change and ocean acidification. If calcifying epibionts are impacted by transient acidification as driven by upwelling events, their increasing prevalence could cause a shift of the fouling communities toward fleshy species. The aim of the present study was to test the sensitivity of selected seaweed macrofoulers to transient elevation of pCO2 in their natural microenvironment, i.e. the boundary layer covering the thallus surface of brown seaweeds. Fragments of the macroalga Fucus serratus bearing an epibiotic community composed of the calcifiers Spirorbis spirorbis (Annelida) and Electra pilosa (Bryozoa) and the non-calcifier Alcyonidium hirsutum (Bryozoa) were maintained for 30 days under three pCO2 conditions: natural 460±59 µatm, present-day upwelling1193±166 µatm and future upwelling 3150±446 µatm. Only the highest pCO2 caused a significant reduction of growth rates and settlement of S. spirorbis individuals. Additionally, S. spirorbis settled juveniles exhibited enhanced calcification of 40% during daylight hours compared to dark hours, possibly reflecting a day-night alternation of an acidification-modulating effect by algal photosynthesis as opposed to an acidification-enhancing effect of algal respiration. E. pilosa colonies showed significantly increased growth rates at intermediate pCO2 (1193 µatm) but no response to higher pCO2. No effect of acidification on A. hirsutum colonies growth rates was observed. The results suggest a remarkable resistance of the algal macro-epibionts to levels of acidification occurring at present day upwellings in the Baltic. Only extreme future

  13. Pedological constraints controlling the occurrence of mire plant bioindicators from north Atlantic formerly frozen soils to present-day Mediterranean sandy wet habitats

    NASA Astrophysics Data System (ADS)

    Geraldes, Miguel; da Conceição Freitas, Maria; Cruces, Anabela; Andrade, César; Oliva, Marc; Neto, Carlos; do Rosário Carvalho, Maria

    2013-04-01

    Unlocking the palaeoenvironmental context, in which present peaty sols in former cold regions of Western Europe, may contribute to the understanding of the actual distribution of three acid-soil vascular plants. Likewise can the role played by similar soil and water conditions (due to other context) be the key to explain their expansion further South. The present work aims to compare the origins and traits of such similar ecotons and to verify how these vascular plants can be use as bioindicators for the presence of peaty soils, picking the proper variables and their geographical variation fits in the Ecological amplitude of the species. The soil and the water are the two compartmeents in which some of the variables might control the present-day distributions of the three taxa. The reactions of a certain number of soil samples carefully taken at shallow depths in the profiles of peaty soils of mires or peat-reach habitats, which cover more than fifty tiny to moderate sampled areas of western Europe (Atlantic Façade and the Iberian Península) and Northwestern Morocco, are being determined in the laboratory of the Geology Department of the University of Lisbon, where some characteristic mire-akin plant taxa have their southernmost range, somewhat in disharmony with meso-to thermomediterranean climates (Rivas Martínez, Global Bioclimatics). Two samples (A and B) were collected per site, the A corresponding to the presence of one of the three bioindicators, the B dug where the species ceases to be present. The present soil processes in the northern part of this sampling is in many cases related to a cold region, glaciated or under periglacial conditions during LGM, but the sedimentary and hydrologic analogies further south might help to explain how euro-siberian species can migrate that long and withstand present-day warmer and drier climates. The pH values of samples were plotted against the depth, and curves, correlations and other possible relationships will be

  14. Present-Day Strain Transfer Across the Yakutat Collision in SW Yukon - SE Alaska: The Death of the Southern Denali Fault?

    NASA Astrophysics Data System (ADS)

    Marechal, A.; Mazzotti, S.; Ritz, J. F.; Ferry, M. A.; Freymueller, J. T.

    2014-12-01

    In SW Yukon-SE Alaska, the present-day Pacific-North America relative motion is highly oblique to the main plate boundary, resulting in strong strain-partitioning tectonics that link the Aleutian subduction to the west to Queen Charlotte transform to the south. This transition region is also the site of present-day orogeny and accretion of the Yakutat Terrane to the Northern Cordillera. Multiple datasets (GPS, geomorphology, seismicity) are integrated to characterize and quantify strain patterns, with particular emphasis on strain partitioning between strike-slip and shortening deformation. New GPS data straddling the main faults (Denali, Totschunda, Fairweather) indicate that, south of the collision corner, 95% of the Pacific-North America strike-slip motion is accommodated on the plate-boundary Fairweather Fault, leaving near-zero motion on the Denali Fault only ~100 km inboard. In contrast, the fault-perpendicular component is strongly distributed between shortening offshore, in the orogen, and inland outward motion. In the region of highest convergence obliquity, GPS data show a diffuse indentor-like deformation, with strong along-strike variations of the main fault slip rates. Preliminary results of a regional geomorphology study give further information about the Denali Fault, where previous data suggest a velocity decrease from 8 mm/yr (Matmon et al.,2006) to 4 mm/yr (Seitz et al., 2010). A high resolution DEM processed from Pleiades satellite imagery highlights a significant vertical component on the Denali Fault and very little to no strike-slip movement in its southern part. Metric-scale displacements are measured along the "inactive" part of the fault showing recent vertical deformation since the Last Glacial Maximum (~20 kyrs ago). In contrast, significant dextral offsets on post-LGM structures are measured on the southern Totschunda Fault. Ongoing datation of geomorphological markers (Be10, OSL) will give us new slip-rate estimates along the southern

  15. Determination of the root-mean-square radius of the deuteron from present-day experimental data on neutron-proton scattering

    SciTech Connect

    Babenko, V. A.; Petrov, N. M.

    2008-10-15

    The correlation between the root-mean-square matter radius of the deuteron, r{sub m}, and its effective radius, {rho}, is investigated. A parabolic relationship between these two quantities makes it possible to determine the root-mean-square radius r{sub m} to within 0.01% if the effective radius {rho} is known. The matter (r{sub m}), structural (r{sub d}), and charge (r{sub ch}) radii of the deuteron are found with the aid of modern experimental results for phase shifts from the SAID nucleon-nucleon database, and their values are fully consistent with their counterparts deduced by using the experimental value of the effective deuteron radius due to Borbely and his coauthors. The charge-radius value of 2.124(6) fm, which was obtained with the aid of the SAID nucleon-nucleon database, and the charge-radius value of 2.126(12) fm, which was obtained with the aid of the experimental value of the effective radius {rho}, are in very good agreement with the present-day chargeradius value of 2.128(11) fm, which was deduced by Sick and Trautmann by processing world-average experimental data on elastic electron scattering by deuterons with allowance for Coulomb distortions.

  16. Sulfur Dioxide and the Production of Sulfuric Acid on Present-Day and Early Mars: Implications for the Lack of Detected Carbonates on the Surface

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.; Summers, Michael E.

    2008-01-01

    In the early history of Mars, volcanic activity associated with the formation of the Tharsis ridge produced a very large amount of atmospheric SO2--on the order of a bar of atmospheric SO2. In the present-day atmosphere of Mars, the lifetime of SO2 is relatively short with a lifetime of less than a day. The short lifetime of SO2 in the present Mars atmosphere makes the production of significant levels of H2SO4 very difficult since the SO2 may be destroyed by various chemical and photochemical processes before the SO2 can be converted to H2SO4. However, photochemical calculations performed and described here, indicate that enhanced atmospheric levels of CO2 in the early atmosphere of Mars resulted in a significantly enhanced atmospheric lifetime for SO2 up to several years. With a significantly enhanced atmospheric lifetime, SO2 could readily form large amounts of H2SO4, which precipitated out of the atmosphere in the form of droplets. The precipitated H2SO4 then reacted with potential surface carbonates, destroying the carbonates and resulting in the abundant and widespread distribution of sulfates on the surface of Mars as detected by recent Mars missions.

  17. Investigations of potential microbial methanogenic and carbon monoxide utilization pathways in ultra-basic reducing springs associated with present-day continental serpentinization: the Tablelands, NL, CAN

    PubMed Central

    Morrill, Penny L.; Brazelton, William J.; Kohl, Lukas; Rietze, Amanda; Miles, Sarah M.; Kavanagh, Heidi; Schrenk, Matthew O.; Ziegler, Susan E.; Lang, Susan Q.

    2014-01-01

    Ultra-basic reducing springs at continental sites of serpentinization act as portals into the biogeochemistry of a subsurface environment with H2 and CH4 present. Very little, however, is known about the carbon substrate utilization, energy sources, and metabolic pathways of the microorganisms that live in this ultra-basic environment. The potential for microbial methanogenesis with bicarbonate, formate, acetate, and propionate precursors and carbon monoxide (CO) utilization pathways were tested in laboratory experiments by adding substrates to water and sediment from the Tablelands, NL, CAD, a site of present-day continental serpentinization. Microbial methanogenesis was not observed after bicarbonate, formate, acetate, or propionate addition. CO was consumed in the live experiments but not in the killed controls and the residual CO in the live experiments became enriched in 13C. The average isotopic enrichment factor resulting from this microbial utilization of CO was estimated to be 11.2 ± 0.2‰. Phospholipid fatty acid concentrations and δ13C values suggest limited incorporation of carbon from CO into microbial lipids. This indicates that in our experiments, CO was used primarily as an energy source, but not for biomass growth. Environmental DNA sequencing of spring fluids collected at the same time as the addition experiments yielded a large proportion of Hydrogenophaga-related sequences, which is consistent with previous metagenomic data indicating the potential for these taxa to utilize CO. PMID:25431571

  18. Anti-HIV drug development: structural features and limitations of present day drugs and future challenges in the successful HIV/AIDS treatment.

    PubMed

    Kumari, Garima; Singh, Ramendra K

    2013-01-01

    Acquired Immune Deficiency Syndrome (AIDS), an immuno-compromized condition, a sequel to untreated human immunodeficiency virus (HIV) infection, inviting several life-threatening diseases, has become one of the most fatal disorders in the recent past because of HIV strain variance due to mutations, passive latency and reservoirs helping in replenishing and reviving the HIV-1 proviral DNA. Scientific efforts have led to the discovery of several effective drugs against HIV and lowered the morbidity and mortality all over the world. However, despite availability of a good number of anti-HIV drugs, the problem, for the foreseeable reasons, stands out as the most chronic disease due to the less tolerability and low accessibility of drugs, life-long expensive treatment, and above all, the emergence of drug resistant viral strains. This review dwells upon HIV infection and its proliferation inside the host system, drug targets, different types of drugs, their structural features and mode of interaction with viral targets and drug regimens. It further focuses on topics of latest interest regarding drug development, fixed dose combinations (FDCs), the limitations of present day drugs with their structural features along with their pharmacodynamics, pharmacokinetics and pharmacogenomics and the challenges in finding a permanent cure for HIV/AIDS. PMID:23092282

  19. Human reponses to historical eruptions of Etna (Sicily) from 1600 to present and their implications for present-day disaster planning

    NASA Astrophysics Data System (ADS)

    Sangster, H.; Chester, D. K.; Duncan, A. M.

    2012-04-01

    Mount Etna in northeastern Sicily (Italy) rises to over 3000 m, covers an area of ca.1750 km2 and is the most active volcano in Europe. Observations of Etna by literate observers stretch back to the classical era and one of the earliest references to an eruption of Etna was by Pindar in his Pythian Odes, to the event of ca. 474-479 B.C. The history of its activity has been reconstructed by scholars up to the present day and records of eruptions are reasonably complete from the early fifteenth century, reliable from 1669, and document the threats and destruction to human settlements and livelihoods. Effusive and explosive activity has occurred continually throughout the historical period and eruptions of Mount Etna have presented numerous eruption styles, from persistent central crater activity, to periodic flank eruptions. From 1600 to 1669 the activity of Etna was characterised by a high volumetric output of lava with a mean eruption rate of 1.19 m3s-1, this was followed by a pause from flank eruptions and the re-establishment of significant activity from the middle of the eighteenth century. After 1750 the output of lava by flank eruptions was lower than in the previous century, with the mean eruption rate falling to 0.18 m3s-1. This paper summarises: the characteristics of the eruptions that occurred between the period of 1600 to present; the particularities of the societal responses over time and the role of the authorities; and, the important lessons this history holds for the management of present-day civil defence planning in the region. People responded to the eruptions at three levels: as members of a family and extended family; as members of a community and, as citizens of the State. The State, however, was a minor player in responding to these eruptions until the early nineteenth century as the State then became more involved in each successive eruption as the responses moved to a more industrial nature rather than pre-industrial. Today emergencies are

  20. Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tides, extra-tropical storm surges and mean sea level

    NASA Astrophysics Data System (ADS)

    Haigh, Ivan D.; Wijeratne, E. M. S.; MacPherson, Leigh R.; Pattiaratchi, Charitha B.; Mason, Matthew S.; Crompton, Ryan P.; George, Steve

    2014-01-01

    The occurrence of extreme water levels along low-lying, highly populated and/or developed coastlines can lead to considerable loss of life and billions of dollars of damage to coastal infrastructure. Therefore it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood management, engineering and future land-use planning. This ensures the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. This paper estimates for the first time present day extreme water level exceedence probabilities around the whole coastline of Australia. A high-resolution depth averaged hydrodynamic model has been configured for the Australian continental shelf region and has been forced with tidal levels from a global tidal model and meteorological fields from a global reanalysis to generate a 61-year hindcast of water levels. Output from this model has been successfully validated against measurements from 30 tide gauge sites. At each numeric coastal grid point, extreme value distributions have been fitted to the derived time series of annual maxima and the several largest water levels each year to estimate exceedence probabilities. This provides a reliable estimate of water level probabilities around southern Australia; a region mainly impacted by extra-tropical cyclones. However, as the meteorological forcing used only weakly includes the effects of tropical cyclones, extreme water level probabilities are underestimated around the western, northern and north-eastern Australian coastline. In a companion paper we build on the work presented here and more accurately include tropical cyclone-induced surges in the estimation of extreme water level. The multi-decadal hindcast generated here has been used primarily to estimate extreme water level exceedance probabilities but could be used more widely in the future for a variety of other research and practical

  1. Paleontological records indicate the occurrence of open woodlands in a dry inland climate at the present-day Arctic coast in western Beringia during the Last Interglacial

    NASA Astrophysics Data System (ADS)

    Kienast, Frank; Wetterich, Sebastian; Kuzmina, Svetlana; Schirrmeister, Lutz; Andreev, Andrei A.; Tarasov, Pavel; Nazarova, Larisa; Kossler, Annette; Frolova, Larisa; Kunitsky, Viktor V.

    2011-08-01

    Permafrost records, accessible at outcrops along the coast of Oyogos Yar at the Dmitry Laptev Strait, NE-Siberia, provide unique insights into the environmental history of Western Beringia during the Last Interglacial. The remains of terrestrial and freshwater organisms, including plants, coleopterans, chironomids, cladocerans, ostracods and molluscs, have been preserved in the frozen deposits of a shallow paleo-lake and indicate a boreal climate at the present-day arctic mainland coast during the Last Interglacial. Terrestrial beetle and plant remains suggest the former existence of open forest-tundra with larch ( Larix dahurica), tree alder ( Alnus incana), birch and alder shrubs ( Duschekia fruticosa, Betula fruticosa, Betula divaricata, Betula nana), interspersed with patches of steppe and meadows. Consequently, the tree line was shifted to at least 270 km north of its current position. Aquatic organisms, such as chironomids, cladocerans, ostracods, molluscs and hydrophytes, indicate the formation of a shallow lake as the result of thermokarst processes. Steppe plants and beetles suggest low net precipitation. Littoral pioneer plants and chironomids indicate intense lake level fluctuations due to high evaporation. Many of the organisms are thermophilous, indicating a mean air temperature of the warmest month that was greater than 13 °C, which is above the minimum requirements for tree growth. These temperatures are in contrast to the modern values of less than 4 °C in the study area. The terrestrial and freshwater organism remains were found at a coastal exposure that was only 3.5 m above sea level and in a position where they should have been under sea during the Last Interglacial when the global sea level was 6-10 m higher than the current levels. The results suggest that during the last warm stage, the site was inland, and its modern coastal situation is the result of tectonic subsidence.

  2. Evaluation of Preindustrial to Present-day Black Carbon and its Albedo Forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    SciTech Connect

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, Drew; Berntsen, T.; Bisiauxs, M.; Cao, J.; Collins, W. J.; Curran, M.; Edwards, R.; Faluvegi, G.; Ghan, Steven J.; Horowitz, L.; McConnell, J.R.; Ming, J.; Myhre, G.; Nagashima, T.; Naik, Vaishali; Rumbold, S.; Skeie, R. B.; Sudo, K.; Takemura, T.; Thevenon, F.; Xu, B.; Yoon, Jin-Ho

    2013-03-05

    As a part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against the observations including 12 ice core records, a long-term surface mass concentrations and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using the NCAR Community Land and Sea-Ice model 4 with prescribed meteorology from 1996-2000, which includes the SNICAR BC-snow model. We evaluated the vertical profile of BC snow concentrations from these offline simulations to using recent BC snowpack measurements. Despite using the same BC emissions, global BC burden differs by approximately a factor of 3 among models due to the differences in aerosol removal parameterizations and simulated meteorology among models; 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However,models agree well on 2.5~3 times increase in the global BC burden from preindustrial to present-day, which matches with the 2.5 times increase in BC emissions. We find a large model diversity at both NH and SH high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC mass concentrations well in Europe and North America except at Jungfrauch and Ispra. However, the models fail to capture the Arctic BC seasonality due tosevere underestimations during winter and spring. Compared to recent snowpack measurements, the simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of observations except for Greenland and Arctic Ocean. However, model and observation differ widely due to missing interannual variations in emissions and possibly due to the choice of the prescribed meteorology period (i.e., 1996-2000).

  3. Constraints of mapped and unfolded slabs on Oligocene to present-day Western Mediterranean plate reconstructions: potential role of north Iberia continental delamination

    NASA Astrophysics Data System (ADS)

    Lee, Yi-Te; Wu, Jonny; Wu, Yi-Min; Suppe, John; Sibuet, Jean-Claude; Chevrot, Sebastien

    2015-04-01

    Seismic tomographic images of subducted lithospheric remnants under the western Mediterranean have provided new constraints for Oligocene to present-day plate reconstructions. In this study, we mapped slabs under the western Mediterranean and Iberia from regional seismic tomography (Chevrot et al., 2014; Bezada et al., 2013) and from MITP08 global tomography (Li et al., 2008). A newly developed method was used to unfold (ie. structurally restore) the mapped slabs to a model spherical Earth surface, minimizing area and shape distortion. Slab constraints were input into plate tectonic reconstructions using Gplates software. Our mapping confirms the existence of western Mediterranean slabs including the Betic-Alboran, Algerian, and Calabrian slabs that were previously identified by Spakman and Wortel (2004). When unfolded these mapped slabs fit together in an Oligocene plate reconstruction, within tomographic resolution limits. Slab stretching was not required. Slab segmentation supports the existence of a North Balearic transform. Here we emphasize the potential importance for western Mediterranean tectonics of antoher slab under Iberia that we call the 'mid-Iberia slab'. This slab was first identified by Sibuet et al. (2004) and interpreted to be a Neotethyan suture. We have mapped this slab in detail from recent regional tomography (Chevrot et al., 2014). Our mapped slab is sub-vertical and strikes E-W under the southern margins of the Duero and Ebro basins. We newly interpret this slab to be delaminated northern Iberian continental lithosphere. We propose that continental delamination occurred during the Oligocene and produced uplifted Iberian Meseta topography, internally-drained basins, and high mean elevations that still persist today. We show how Oligocene northern Iberian continental delamination could have initiated subduction and rollback of the western Mediterranean

  4. Analysis of the global atmospheric methane budget using ECHAM-MOZ simulations for present-day, pre-industrial time and the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Basu, A.; Schultz, M. G.; Schröder, S.; Francois, L.; Zhang, X.; Lohmann, G.; Laepple, T.

    2014-01-01

    Atmospheric methane concentrations increased considerably from pre-industrial (PI) to present times largely due to anthropogenic emissions. However, firn and ice core records also document a notable rise of methane levels between the Last Glacial Maximum (LGM) and the pre-industrial era, the exact cause of which is not entirely clear. This study investigates these changes by analyzing the methane sources and sinks at each of these climatic periods. Wetlands are the largest natural source of methane and play a key role in determining methane budget changes in particular in the absence of anthropogenic sources. Here, a simple wetland parameterization suitable for coarse-scale climate simulations over long periods is introduced, which is derived from a high-resolution map of surface slopes together with various soil hydrology parameters from the CARAIB vegetation model. This parameterization was implemented in the chemistry general circulation model ECHAM5-MOZ and multi-year time slices were run for LGM, PI and present-day (PD) climate conditions. Global wetland emissions from our parameterization are 72 Tg yr-1 (LGM), 115 Tg yr-1 (PI), and 132 Tg yr-1 (PD). These estimates are lower than most previous studies, and we find a stronger increase of methane emissions between LGM and PI. Taking into account recent findings that suggest more stable OH concentrations than assumed in previous studies, the observed methane distributions are nevertheless well reproduced under the different climates. Hence, this is one of the first studies where a consistent model approach has been successfully applied for simulating methane concentrations over a wide range of climate conditions.

  5. Interactive effects of ocean acidification and warming on coral reef associated epilithic algal communities under past, present-day and future ocean conditions

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Cantin, N. E.; Strahl, J.; Kaniewska, P.; Bay, L.; Wild, C.; Uthicke, S.

    2016-06-01

    Epilithic algal communities play critical ecological roles on coral reefs, but their response to individual and interactive effects of ocean warming (OW) and ocean acidification (OA) is still largely unknown. We investigated growth, photosynthesis and calcification of early epilithic algal community assemblages exposed for 6 months to four temperature profiles (-1.1, ±0.0, +0.9, +1.6 °C) that were crossed with four carbon dioxide partial pressure (pCO2) levels (360, 440, 650, 940 µatm), under flow-through conditions and natural light regimes. Additionally, we compared the cover of heavily calcified crustose coralline algae (CCA) and lightly calcified red algae of the genus Peyssonnelia among treatments. Increase in cover of epilithic communities showed optima under moderately elevated temperatures and present pCO2, while cover strongly decreased under high temperatures and high-pCO2 conditions, particularly due to decreasing cover of CCA. Similarly, community calcification rates were strongly decreased at high pCO2 under both measured temperatures. While final cover of CCA decreased under high temperature and pCO2 (additive negative effects), cover of Peyssonnelia spp. increased at high compared to annual average and moderately elevated temperatures. Thus, cover of Peyssonnelia spp. increased in treatment combinations with less CCA, which was supported by a significant negative correlation between organism groups. The different susceptibility to stressors most likely derived from a different calcification intensity and/or mineral. Notably, growth of the epilithic communities and final cover of CCA were strongly decreased under reduced-pCO2 conditions compared to the present. Thus, CCA may have acclimatized from past to present-day pCO2 conditions, and changes in carbonate chemistry, regardless in which direction, negatively affect them. However, if epilithic organisms cannot further acclimatize to OW and OA, the interacting effects of both factors may change

  6. Aerosol Direct, Indirect, Semidirect, and Surface Albedo Effects from Sector Contributions Based on the IPCC AR5 Emissions for Preindustrial and Present-day Conditions

    NASA Technical Reports Server (NTRS)

    Bauer, Susanne E.; Menon, Surabi

    2012-01-01

    The anthropogenic increase in aerosol concentrations since preindustrial times and its net cooling effect on the atmosphere is thought to mask some of the greenhouse gas-induced warming. Although the overall effect of aerosols on solar radiation and clouds is most certainly negative, some individual forcing agents and feedbacks have positive forcing effects. Recent studies have tried to identify some of those positive forcing agents and their individual emission sectors, with the hope that mitigation policies could be developed to target those emitters. Understanding the net effect of multisource emitting sectors and the involved cloud feedbacks is very challenging, and this paper will clarify forcing and feedback effects by separating direct, indirect, semidirect and surface albedo effects due to aerosols. To this end, we apply the Goddard Institute for Space Studies climate model including detailed aerosol microphysics to examine aerosol impacts on climate by isolating single emission sector contributions as given by the Coupled Model Intercomparison Project Phase 5 (CMIP5) emission data sets developed for Intergovernmental Panel on Climate Change (IPCC) AR5. For the modeled past 150 years, using the climate model and emissions from preindustrial times to present-day, the total global annual mean aerosol radiative forcing is -0.6 W/m(exp 2), with the largest contribution from the direct effect (-0.5 W/m(exp 2)). Aerosol-induced changes on cloud cover often depends on cloud type and geographical region. The indirect (includes only the cloud albedo effect with -0.17 W/m(exp 2)) and semidirect effects (-0.10 W/m(exp 2)) can be isolated on a regional scale, and they often have opposing forcing effects, leading to overall small forcing effects on a global scale. Although the surface albedo effects from aerosols are small (0.016 W/m(exp 2)), triggered feedbacks on top of the atmosphere (TOA) radiative forcing can be 10 times larger. Our results point out that each

  7. Little Ice Age versus Present Day: Comparison of Temperature, Precipitation and Seasonality in Speleothem Records from the Han-sur-Lesse Cave, Belgium.

    NASA Astrophysics Data System (ADS)

    Vansteenberge, S.; Van Opdenbosch, J.; Van Rampelbergh, M.; Verheyden, S.; Keppens, E.; Cheng, H.; Edwards, R. L.; Claeys, P. F.

    2015-12-01

    The Proserpine stalagmite is a 2 m large, tabular-shaped speleothem located in the Han-sur-Lesse cave in Belgium. The speleothem formed over the last 1000 years and is still growing. High-accuracy U/Th datings have indicated exceptionally high growth-rates of up to 2 mm per year. This, together with a well expressed annual layering, makes the Proserpine stalagmite an ideal candidate for high-resolution paleoclimate reconstructions of the last millennium. Previous work, including over 10 years of cave monitoring, has already learned us how short-term, i.e. decadal to seasonal, climate variations are incorporated within speleothem calcite from the Han-sur-Lesse cave system. It has been shown that δ18O and δ13C stable isotopes and trace element proxies of recently formed calcite reflect seasonal variations in temperature and precipitation of the near-cave environment (Verheyden et al, 2008; Van Rampelbergh et al., 2014). Now, this knowledge was used to infer local climate parameters further back in time to the period of +/- 1620-1630 CE, corresponding to one of the cold peaks within the Little Ice Age. Speleothem calcite was sampled at sub-annual resolution, with approximately 11 samples per year, for stable isotope analysis. LA-ICP-MS and µXRF analyses resulted in time series of trace elements. Preliminary results indicate a well expressed seasonal signal in δ13C and trace element composition but a multi-annual to decadal trend in δ18O. This combined proxy study eventually enables comparison of the expression of seasonality and longer term climate variations between a Little Ice Age cold peak and Present Day. References: Verheyden, S. et al., 2008, Monitoring climatological, hydrological and geochemical parameters in the Père Noël cave (Belgium): implication for the interpretation of speleothem isotopic and geochemical time-series. International Journal of Speleology, 37(3), 221-234. Van Rampelbergh, M. et al., 2014, Seasonal variations recorded in cave

  8. Grainsize Patterns and Bed Evolution of the Rhone River (France): A Present-day Snapshot Following a Century and a Half of Human Modifications

    NASA Astrophysics Data System (ADS)

    Michal, T.; Parrot, E.; Piegay, H.

    2014-12-01

    Over the past 150 years the Rhône River has been heavily altered by human infrastructures. The first wave (1860 - 1930) of modifications consisted of dikes and groynes designed to narrow the channel and promote incision in order to facilitate navigation. A second period (1948 - 1986) involved the construction of a series of canals and dams for hydroelectricity production. These works bypass multiple reaches of the original channel and drastically reduce the discharge and sediment load reaching them. A comprehensive study underway is aimed at describing the present-day morphology of the Rhone along its 512 km length from its source at Lake Geneva to its sink at the Mediterranean Sea and quantifying the role of management works in the evolution to its current state. Grainsize distributions and armour ratios were determined using a combination of Wolman counts on bars and in shallow channels and dredge samples collected from a boat in navigable reaches. Long profiles were constructed from historical bathymetric maps and bathymetric data collected between 1950 - 2010. Differential long profiles highlighting changes in bed elevation due to sediment storage and erosion were analyzed for three different periods: post-channelization, post-dam construction, and a recent period of major floods. Results show a complex discontinuous pattern in grainsize associated with hydraulic discontinuities imposed by dams. The D50 for bypass reaches is 45 mm compared to a D50 of 34 mm in the non-bypass reaches. The lower D50 as well as a finer tailed distribution in non-bypass reaches reflects fining associated with storage upstream of dams. Armour ratios are on average around 2 but are notably higher for reaches in the middle section of the Rhone. The average incision rate was 1.8 cm/yr for the period of post-channelization and 1.2 cm/yr following dam construction, suggesting the post-dam Rhone was already partially armoured due to incision associated with channelization preceding dam

  9. Aerosol direct, indirect, semidirect, and surface albedo effects from sector contributions based on the IPCC AR5 emissions for preindustrial and present-day conditions

    NASA Astrophysics Data System (ADS)

    Bauer, Susanne E.; Menon, Surabi

    2012-01-01

    The anthropogenic increase in aerosol concentrations since preindustrial times and its net cooling effect on the atmosphere is thought to mask some of the greenhouse gas-induced warming. Although the overall effect of aerosols on solar radiation and clouds is most certainly negative, some individual forcing agents and feedbacks have positive forcing effects. Recent studies have tried to identify some of those positive forcing agents and their individual emission sectors, with the hope that mitigation policies could be developed to target those emitters. Understanding the net effect of multisource emitting sectors and the involved cloud feedbacks is very challenging, and this paper will clarify forcing and feedback effects by separating direct, indirect, semidirect and surface albedo effects due to aerosols. To this end, we apply the Goddard Institute for Space Studies climate model including detailed aerosol microphysics to examine aerosol impacts on climate by isolating single emission sector contributions as given by the Coupled Model Intercomparison Project Phase 5 (CMIP5) emission data sets developed for Intergovernmental Panel on Climate Change (IPCC) AR5. For the modeled past 150 years, using the climate model and emissions from preindustrial times to present-day, the total global annual mean aerosol radiative forcing is -0.6 W/m2, with the largest contribution from the direct effect (-0.5 W/m2). Aerosol-induced changes on cloud cover often depends on cloud type and geographical region. The indirect (includes only the cloud albedo effect with -0.17 W/m2) and semidirect effects (-0.10 W/m2) can be isolated on a regional scale, and they often have opposing forcing effects, leading to overall small forcing effects on a global scale. Although the surface albedo effects from aerosols are small (0.016 W/m2), triggered feedbacks on top of the atmosphere (TOA) radiative forcing can be 10 times larger. Our results point out that each emission sector has varying

  10. Submarine gravitative mass movements in the ``Corinth Gulf'' graben in Greece. A natural laboratory for the enhancement of present day knowledge on mass movements.

    NASA Astrophysics Data System (ADS)

    Papatheodorou, G.; Stefatos, A.; Christodoulou, D.; Ferentinos, G.

    2003-04-01

    caused by the deformation of the underlying sediments. This can be attributed to the partial loss of sediment strength due to either the remoulding or excess pore fluid pressure caused by the cyclic loading induced by the earthquake. Historical observations give evidence that: (i) coastal mass movements like those described above have also occurred in the past, (ii) mass movements have been triggered by earthquakes or heavy rain and (iii) the frequency occurrence of mass movements all over the Corinth Gulf graben may be once in every two or three years. These mass movements have caused destruction to the coastal infrastructure and also to offshore submarine cables. The review of the state of the art on the existing knowledge suggests, that in the past three decades, there have been great scientific and engineering advances in the recognition of mass movements on the seafloor and of the basic geological processes involved. There is however, a lack of scientific knowledge related to the prediction of the reactivation of existing mass movements and to the identification of slopes prone to failure. This knowledge could be acquired by the continuous monitoring of the changes in the physical and mechanical properties of the sediments. The study of the continuous changes in the sediment properties is hindered mainly by the high cost of monitoring in the unfriendly ocean environment. Taking the aforementioned into consideration, and bearing in mind that the Gulf of Corinth is a semi-enclosed embayment characterized by calm sea conditions, the Gulf would therefore, be an ideal natural laboratory for the further advancement of present day knowledge on mass movement processes and slope stability prediction.

  11. Evaluation of preindustrial to present-day black carbon and its albedo forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, D. T.; Bernsten, T.; Bisiaux, M. M.; Cao, J.; Collins, W. J.; Curran, M.; Edwards, R.; Faluvegi, G.; Ghan, S.; Horowitz, L. W.; McConnell, J. R.; Ming, J.; Myhre, G.; Nagashima, T.; Naik, V.; Rumbold, S. T.; Skeie, R. B.; Sudo, K.; Takemura, T.; Thevenon, F.; Xu, B.; Yoon, J.-H.

    2013-01-01

    As part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against observations including 12 ice core records, long-term surface mass concentrations, and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using offline models with prescribed meteorology from 1996-2000. We evaluate the vertical profile of BC snow concentrations from these offline simulations using the recent BC snowpack measurements. Despite using the same BC emissions, the global BC burden differs by approximately a factor of 3 among models due to differences in aerosol removal parameterizations and simulated meteorology: 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However, the global BC burden from preindustrial to present-day increases by 2.5-3 times with little variation among models, roughly matching the 2.5-fold increase in total BC emissions during the same period.We find a large divergence among models at both Northern Hemisphere (NH) and Southern Hemisphere (SH) high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC surface mass concentrations well in Europe and North America except at Ispra. However, the models fail to predict the Arctic BC seasonality due to severe underestimations during winter and spring. The simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of the BC snowpack measurements except for Greenland and the Arctic Ocean. For the ice core evaluation, models tend to adequately capture both the observed temporal trends and the magnitudes at Greenland sites. However, models fail to predict the decreasing trend of BC depositions/ice core concentrations from the 1950s to the 1970s in most Tibetan Plateau ice cores. The distinct temporal trend at the Tibetan Plateau ice cores

  12. Late Miocene to present-day exhumation and uplift of the Internal Zone of the Rif chain: Insights from low temperature thermochronometry and basin analysis

    NASA Astrophysics Data System (ADS)

    Romagny, A.; Ph. Münch; Cornée, J.-J.; Corsini, M.; Azdimousa, A.; Melinte-Dobrinescu, M. C.; Drinia, H.; Bonno, M.; Arnaud, N.; Monié, P.; Quillévéré, F.; Ben Moussa, A.

    2014-07-01

    Located on the margin of the west Alboran basin, the Gibraltar Arc (Betic-Rif mountain belt) displays post-Pliocene vertical movements evidenced by uplifted marine sedimentary basins and marine terraces. Quantification of vertical movements is an important clue to understand the origin of present-day relief generation in the Betic-Rif mountain chain together with the causes of the Messinian Salinity Crisis. In this paper, we present the results of a pluridisciplinary study combining an analysis of low temperature thermochronology and Pliocene basins evolution to constrain the exhumation history and surface uplift of internals units of the Rif belt (Northern Morocco). The mean (U-Th)/He apatite ages obtained from 11 samples are comprised between 14.1 and 17.8 Ma and display a wide dispersion, which could be explained by a great variability of apatite chemistries in the analyzed samples. No correlations between altitude and age have been found along altitudinal profile suggesting a rapid exhumation during this period. Thermal modeling using our (U-Th)/He apatite ages and geochronological data previously obtained in the same area (40Ar/39Ar and K/Ar data on biotite, zircon and apatite fission track) allow us to propose a cooling history. The rocks suffered a rapid cooling at 60-100 °C/Ma between 22.5 and 19 Ma, then cooled to temperatures around 40 °C between 19 and 18 Ma. They were re-heated at around 110 °C between 18 and 15 Ma then rapidly cooled and exhumed to reach the surface temperature at around 13 Ma. The re-heating could be related to a renewal in thrusting and burying of the inner zones. Between 15 and 13 Ma the cooling resumed at a rate of 50 °C/Ma indicating an exhumation rate of 0.8 mm/y considering an average 40 °C/km geothermal gradient. This exhumation may be linked to the extension in the Alboran Sea. Otherwise biostratigraphic and sedimentological analysis of Pliocene basins of the internal Rif provided informations on the more recent events

  13. Benthic foraminifera from the deep-water Niger delta (Gulf of Guinea): Assessing present-day and past activity of hydrate pockmarks

    NASA Astrophysics Data System (ADS)

    Fontanier, C.; Koho, K. A.; Goñi-Urriza, M. S.; Deflandre, B.; Galaup, S.; Ivanovsky, A.; Gayet, N.; Dennielou, B.; Grémare, A.; Bichon, S.; Gassie, C.; Anschutz, P.; Duran, R.; Reichart, G. J.

    2014-12-01

    13C values. Dead faunas carry a complex time-averaged message, integrating taphonomic gains and losses related to the temporal variability of gas emission. They reveal major faunal differences that may be useful to detect gas hydrate seepages in different pockmark stages.

  14. Cosmology: from Pomeranchuk to the Present Day

    NASA Astrophysics Data System (ADS)

    Dolgov, A. D.

    A short and, due to lack of time (half a century of the science progress in half an hour), rather superficial review on the development of cosmology for scientists working on particle and nuclear physics is presented. The introductory historical part is mostly dedicated to the fundamental works done in Russia (USSR), but not always well known outside the country. Next, the key papers on theory and on astronomical observations, which determined the progress in cosmology during the last half-century or posed crucial problem, are discussed. Among them there are inflation, baryogenesis, dark matter, dark energy, the vacuum energy problem, modification of gravity at large scales, and angular fluctuations of the cosmic microwave background radiation. The presentation is probably biased towards cosmology as it is seen from Russia (or from ITEP) and reflects personal prejudice of the author.

  15. Cosmology: from Pomeranchuk to the present day

    NASA Astrophysics Data System (ADS)

    Dolgov, A. D.

    2014-02-01

    A review of half a century of cosmology is presented for an intended audience of elementary particle physicists. The review is based on a half-hour seminar talk (at the Institute of Theoretical and Experimental Physics, ITEP) and is therefore brief and superficial. The introductory historical section is mostly devoted to the fundamental work done in, but not always known outside, Russia (USSR). Foundational works and astronomical observations instrumental in shaping the field are discussed, as are inflation, baryosynthesis, dark matter and dark energy, vacuum energy, large-scale gravity modifications, and microwave background angular fluctuations. The presentation is admittedly not entirely objective but rather is given from the Russian (ITEP) perspective and is influenced by the author's personal views and biases.

  16. [Present day Marxist sociology and psychoanalysis].

    PubMed

    Biran, S

    1979-01-01

    The main common theme in psychoanalysis and Marxist sociology is the understanding that it is not consciousness that determines being, but being (spiritual, social) that determines consciousness. The different variations of Marxist movements today are in fact distant from Marx's theory of sociology. They have become representatives of utopian socialism, using anarchistic methods to achieve that aim. This development can only be understood as a social neurosis, with the narcistic frustation of the intellectual class as its cause, and grandiose claims, intolerance, dogmatic thinking and destructive behaviour as its symptoms. The only justified criticism of psychoanalysis from the pseudo-Marxist side is based on the imperfection and error in the analytical doctrine of superego. This should be replaced by the idea of conscious, subjective, emotional morality which clearly explains the aggression contained in social structures. PMID:498762

  17. Global three-dimensional model calculations of the budgets and present-day atmospheric lifetimes of CF2ClCFCl2 (CFC-113) and CHClF2 (CFC-22)

    NASA Technical Reports Server (NTRS)

    Golombek, Amram; Prinn, Ronald G.

    1989-01-01

    The annual percentage increases in concentrations of the chlorofluorocarbons CFC-113 (an industrial solvent) and CFC-22 (a refrigerant) are the highest among major chlorofluorocarbons in the atmosphere today. The present-day atmospheric lifetimes for these species are computed using a global three-dimensional dynamical-chemical model. The present-day lifetimes of both are long (15.5 years for CFC-22 and 136 or 195 years for CFC-113, depending on assumed O2 absorption cross sections), underscoring the need to decrease their emissions in order to minimize their future role in ozone destruction and greenhouse warming.

  18. Revealing Rembrandt

    PubMed Central

    Parker, Andrew J.

    2014-01-01

    The power and significance of artwork in shaping human cognition is self-evident. The starting point for our empirical investigations is the view that the task of neuroscience is to integrate itself with other forms of knowledge, rather than to seek to supplant them. In our recent work, we examined a particular aspect of the appreciation of artwork using present-day functional magnetic resonance imaging (fMRI). Our results emphasized the continuity between viewing artwork and other human cognitive activities. We also showed that appreciation of a particular aspect of artwork, namely authenticity, depends upon the co-ordinated activity between the brain regions involved in multiple decision making and those responsible for processing visual information. The findings about brain function probably have no specific consequences for understanding how people respond to the art of Rembrandt in comparison with their response to other artworks. However, the use of images of Rembrandt's portraits, his most intimate and personal works, clearly had a significant impact upon our viewers, even though they have been spatially confined to the interior of an MRI scanner at the time of viewing. Neuroscientific studies of humans viewing artwork have the capacity to reveal the diversity of human cognitive responses that may be induced by external advice or context as people view artwork in a variety of frameworks and settings. PMID:24795552

  19. Using present-day patterns of interseismic coupling to model the C.E. 1707 Hōei earthquake and simulate tsunami inundation of Lake Ryuuoo in the Bungo Channel, southwestern Japan

    NASA Astrophysics Data System (ADS)

    Baranes, H. E.; Woodruff, J. D.; Loveless, J. P.; Cheng, W.; Weiss, R.; Kanamaru, K.

    2015-12-01

    The C.E. 1707 Hōei event is often considered the worst-case scenario for a Nankai Trough earthquake and tsunami impacting southwestern Japan, and recent estimates of the earthquake's magnitude have exceeded MW 9. However, when paired with tsunami simulations, previously published earthquake models for the event fail to match sedimentological and historical records of 1707 tsunami height in Shikoku and Kyushu. Specifically, models do not produce a sufficiently large tsunami in the northern Bungo Channel and Seto Inland Sea without also over-predicting tsunami heights along the open Pacific coastlines of Shikoku and Kyushu. Here, we apply a newly developed rupture model that uses present-day patterns of geodetically imaged interseismic coupling to inform patterns in coseismic slip. Along the southwestern extent of the plate interface (the Hyuga-nada area), there is a region of weak coupling up-dip along the trench axis and a region of strong coupling down-dip beneath Shikoku and Kyushu. Following this pattern, the new earthquake model produces less coseismic uplift offshore and greater subsidence in an inland region that includes the Bungo Channel. This combination of regional subsidence and a tsunami wave more focused to the Bungo Channel results in inundation patterns more consistent with historical and sedimentological observations in the Hyuga-nada area. We also run the tsunami simulation on a high-resolution grid around Lake Ryuuoo, a back-barrier lake in the northern Bungo Channel that contains a marine overwash deposit from the 1707 tsunami. We apply a simple sediment transport model to demonstrate that the coupling-based rupture scenario produces flow over Lake Ryuuoo's barrier capable of transporting the maximum grain size observed in the lake's 1707 deposit. These findings suggest that spatial trends in our present-day coupling model are more consistent with inundation patterns observed for large tsunamis generated by coseismic rupture along the Nankai

  20. Seafloor morphology of the Eurasia-Nubia (Africa) plate boundary between the Tore-Madeira Rise and the Straits of Gibraltar: a case of coexistent Mesozoic through Present day features of tectonic, oceanographic and sedimentary origin

    NASA Astrophysics Data System (ADS)

    Terrinha, Pedro; Duarte, João.; Valadares, Vasco; Batista, Luis; Zitellini, Nevio; Grácia, Eulalia; Lourenço, Nuno; Rosas, Filipe; Roque, Cristina

    2010-05-01

    The joint use of more than 10.000 km multichannel seismic reflection profiles and 180.000km2 of multibeam swath bathymetry and backscatter allowed for a new vision of the seafloor tectonic and geomorphic processes of the area that encompasses the present day plate boundary between Africa and Eurasia, between the Gibraltar Straits and the Tore-Madeira Rise, in the southern sector of the North Atlantic Ocean. The interpretation of this data allowed for the detailed description of the seafloor morphology (i.e. a morphologic map) and the classification of the morphologic features in what respects the genetic process and age. It can be seen that in the same region coexist morphologic features that result from tectonic processes associated with the Triassic-Cretaceous break-up of Pangea, the Paleogene-Miocene compressive phase, the Miocene through Present subduction under the Gibraltar Arc (Gutscher et al., 2002), the Pliocene-Quaternary wrench tectonics and possible coeval plate boundary (Zitellini et al., 2009), the Present day mud volcanism and propagation of the compressive deformation along the West Continental Margin of Portugal (Terrinha et al., 2009). Interpretation of the seismic profiles together with the bathymetry allows the understanding of endogenous and exogenous processes that creates reliefs associated with active structures (related to the Miocene through Present compressive stress field). Other reliefs generated in Mesozoic times by analogous processes can be as well preserved as these active ones. In what concerns exogenous processes, the analysis of the two datasets (reflection seismics and bathymetry) allowed for the description of morphologic features associated with oceanic currents that interact with the seafloor forming these important features. As is the case of the well known active contourites but also less known features, like giant scours at 4 km water depth that have recently been described, suggesting the interaction of deep currents and

  1. Sedimentological imprints of environmental variability at the Balkan Peninsula on the sediment sequence of Lake Ohrid (Macedonia, Albania) between the Mid Pleistocene Transition and present days: The ICDP SCOPSCO project

    NASA Astrophysics Data System (ADS)

    Francke, Alexander; Wagner, Bernd; Leicher, Niklas; Raphael, Gromig; Leng, Melanie; Lacey, Jack; Vogel, Hendrik; Baumgarten, Henrike; Thomas, Wonik; Zanchetta, Giovanni; Roberto, Sulpizio; Krastel, Sebastian; Lindhorst, Katja

    2015-04-01

    The UNESCO World Heritage site of Lake Ohrid in the Balkans is thought to be the oldest, continuously existing lake in Europe. In order to unravel the geological and evolutionary history of the lake, a deep drilling campaign was conducted in spring 2013 under the umbrella of the ICDP SCOPSCO project. At the coring site "DEEP" in central parts of the lake, more than 1,500 m of sediments were recovered down to a penetration depth of 569 m blf. This sediment sequence is assumed to be more than 1.2 Ma old and likely covers the entire lacustrine deposits of the Lake Ohrid Basin. Currently, an age model for the upper 260m of the DEEP- site sequence is available. This age model is based on chronological tie points (tephrochronology), and wiggle matching of down hole logging data and (bio-)geochemistry data (XRF, TIC, TOC) from the core sequence to the global benthic stack LR04 and local insolation patterns. The data suggests that the upper 260 m of the DEEP-site sequence corresponds to the time period between the Mid Pleistocene Transition (MPT) and present days. During this period, the sedimentological properties of the sediments show a strong dependency on environmental variability in the area. Interglacial deposits appear massive or marbled, contain up to 80 % of CaCO3 (high TIC), high amounts of organic matter (high TOC) and biogenic silica (high BSi), and low contents of clastic material. Glacial deposits are predominantly marbled and calcite is generally absent. Similarly, the amounts of organic matter and biogenic silica are low, and glacial sediments predominately consist of clastic matter. Distinct layers of siderite and uniformly distributed Fe- or Mn- oxides occur in the glacial deposits, vivianite concretions occur in both the glacial and interglacial periods. High CaCO3 contents in deposits formed during warm (interglacial) periods are also known from studies on short pilot cores from Lake Ohrid and are triggered by increased productivity in the lake, such as

  2. Assessing the volcanic hazard for Rome: 40Ar/39Ar and In-SAR constraints on the most recent eruptive activity and present-day uplift at Colli Albani Volcanic District

    NASA Astrophysics Data System (ADS)

    Marra, F.; Gaeta, M.; Giaccio, B.; Jicha, B. R.; Palladino, D. M.; Polcari, M.; Sottili, G.; Taddeucci, J.; Florindo, F.; Stramondo, S.

    2016-07-01

    We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993-2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress-field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD.

  3. Genetic structure and forensic parameters of 38 Indels for human identification purposes in eight Mexican populations.

    PubMed

    Martínez-Cortés, G; Gusmão, L; Pereira, R; Salcido, V H; Favela-Mendoza, A F; Muñoz-Valle, J F; Inclán-Sánchez, A; López-Hernández, L B; Rangel-Villalobos, H

    2015-07-01

    Insertion-deletions for human identification purposes (HID-Indels) offer advantages to solve particular forensic situations and complex paternity cases. In Mexico, admixed population known as Mestizos is the largest (∼90%), plus a number of Amerindian groups (∼10%), which have not been studied with HID-Indels. For this reason, allele frequencies and forensic parameters for 38 HID-Indels were estimated in 531 unrelated individuals from one Amerindian (Purépecha) and seven Mestizo populations from different regions of the country. Genotype distribution was in agreement with Hardy-Weinberg expectations in almost all loci/populations. The linkage disequilibrium (LD) test did not reveal possible associations between loci pairs in all eight Mexican populations. The combined power of discrimination was high in all populations (PD >99.99999999998%). However, the power of exclusion of the 38 HID-Indel system (PE >99.6863%) was reduced regarding most of autosomal STR kits. The assessment of genetic structure (AMOVA) and relationships between populations (FST) demonstrated significant differences among Mexican populations, mainly of the Purépecha Amerindian group. Among Mexican-Mestizos, three population clusters consistent with geography were defined: (i) North-West region: Chihuahua, Sinaloa, and Jalisco; (ii) Central-Southern region: Mexico City, Veracruz and Yucatan; (iii) South region: Chiapas. In brief, this report validates the inclusion of the 38 HID-Indel system in forensic casework and paternity cases in seven Mexican-Mestizo populations from different regions, and in one Mexican Amerindian group. PMID:25988907

  4. Present-day aeolian activity in Herschel Crater, Mars

    NASA Astrophysics Data System (ADS)

    Cardinale, Marco; Silvestro, Simone; Vaz, David A.; Michaels, Timothy; Bourke, Mary C.; Komatsu, Goro; Marinangeli, Lucia

    2016-02-01

    In this report, we show evidence for ripple and dune migration in Herschel Crater on Mars. We estimate an average dune migration of 0.8 m and a minimum ripple migration of 1.1 m in a time span of 3.7 Earth-years. These dunes and ripples are mainly shaped by prevailing winds coming from the north, however we also report the presence of secondary winds which elongate the barchans' horns. Such a complex wind scenario is likely caused by the influence of winds blowing off the western crater rim as suggested by the Mars Regional Atmospheric Modeling System (MRAMS), an atmospheric mesoscale model. A multi-directional wind regime at the local scale is also supported by the observed bimodal distribution of the ripple trends. For the first time, a survey integrating the assessment of dune and ripple migration is presented, showing how dune topography can influence the migration patterns of ripples and how underlying topography appears to control the rates of dune migration.

  5. [Present-day metal-cutting tools and working conditions].

    PubMed

    Kondratiuk, V P

    1990-01-01

    Polyfunctional machine-tools of a processing centre type are characterized by a set of hygienic advantages as compared to universal machine-tools. But low degree of mechanization and automation of some auxiliary processes, and constructional defects which decrease the ergonomic characteristics of the tools, involve labour intensity in multi-machine processing. The article specifies techniques of allowable noise level assessment, and proposes hygienic recommendations, some of which have been introduced into practice. PMID:2328919

  6. Likelihood of nitrogen condensation in Titan's present-day atmosphere

    NASA Astrophysics Data System (ADS)

    Tokano, Tetsuya

    2016-04-01

    The temperature in Titan's upper troposphere measured by the Huygens Probe is relatively close to the nitrogen condensation point. This poses the question as to whether seasonal nitrogen condensation might occur on Titan analogously to seasonal carbon dioxide condensation on Mars. The likelihood of nitrogen condensation in Titan's atmosphere is investigated using tropospheric temperature data obtained by Cassini radio occultations and simulation with a general circulation model (GCM). The observed tropospheric temperature generally decreases towards both poles but does not reach the nitrogen condensation point anywhere. However, Cassini may not have sounded the coldest season and area in Titan's troposphere. The GCM simulation shows that in the upper troposphere the variable solar distance associated with Saturn's orbital eccentricity has a larger impact on the seasonal polar temperature variation than the variable solar declination associated with Saturn's obliquity. In the upper troposphere relevant for nitrogen condensation the annual minimum polar temperature is predicted to occur around the northern autumnal equinox, approximately one season after aphelion. This temperature is then 1-2 K lower than in the season of the Cassini/Huygens mission. It is possible if not certain that some nitrogen condensation with cloud formation occurs in the northern and southern polar region in the upper troposphere around the northern autumnal equinox. Under the present orbital parameters of Saturn and Titan nitrogen condensation may occur more frequently near the south pole than near the north pole.

  7. [Fire worship on Soratte: form prehistory to present days].

    PubMed

    Falchetti, Mario; Ottini, Laura

    2013-01-01

    Fire has always been involved in human thoughts, believes and actions. For many psychological reasons fire has been considered as living power: red as the human blood, warm as the human body, clearly shines in the night. Fire worship is very common, especially in regions where terrestrial fire is believed to be the image of the heavenly fire. Fire worship has represented the base for symbolic systems involved in the cultural-anthropological evolution of populations settled close to mount Soratte. Fire cults in this region have originated in independent and long-time separated contexts, according to available knowledge. Hirpi Sorani, ancient inhabitants of mount Soratte territory, celebrated Sorano Apollo by a famous fire walking ceremony, with a likely cathartic and apotropaic meaning, as reported by ancient Roman writers. The victory of Christianity over paganism caused the decline of these religious practices. The beginning of the XIX century witnessed the establishment ofa new kind of devotion to the Virgin Mary at the mount Soratte. Today, this religious piety-linked identity has weakened due to changes in lifestyles,from an agricultural to one based on outside home employment, and has been largely shifted on cultural and anthropological bases. In conclusion, fire worship at mount Soratte has evolved because of external influences and local inhabitants have reacted by asserting their own identity. PMID:25807785

  8. Present-day uplift of the western Alps

    NASA Astrophysics Data System (ADS)

    Nocquet, J.-M.; Sue, C.; Walpersdorf, A.; Tran, T.; Lenôtre, N.; Vernant, P.; Cushing, M.; Jouanne, F.; Masson, F.; Baize, S.; Chéry, J.; van der Beek, P. A.

    2016-06-01

    Collisional mountain belts grow as a consequence of continental plate convergence and eventually disappear under the combined effects of gravitational collapse and erosion. Using a decade of GPS data, we show that the western Alps are currently characterized by zero horizontal velocity boundary conditions, offering the opportunity to investigate orogen evolution at the time of cessation of plate convergence. We find no significant horizontal motion within the belt, but GPS and levelling measurements independently show a regional pattern of uplift reaching ~2.5 mm/yr in the northwestern Alps. Unless a low viscosity crustal root under the northwestern Alps locally enhances the vertical response to surface unloading, the summed effects of isostatic responses to erosion and glaciation explain at most 60% of the observed uplift rates. Rock-uplift rates corrected from transient glacial isostatic adjustment contributions likely exceed erosion rates in the northwestern Alps. In the absence of active convergence, the observed surface uplift must result from deep-seated processes.

  9. [Fungus patents: from Pasteur to the present day].

    PubMed

    Bernardo-Álvarez, María Ángela

    2012-01-01

    At the end of the 19(th) century, the American Patent Office granted the patent known as "Pasteur's application", claiming the protection of a yeast strain. Since that date, the debate around biotechnology patents, especially for those that affect living organisms or part of them, has grown exponentially. In the present article, the Patent Law is reviewed, pointing out the particular problems about fungi or parts of them. Also, some of the fungus patents are discussed from the perspective of the ethical, economical, social and environmental aspects of these kind of patents. PMID:22677466

  10. Teaching with Social Media: Disrupting Present Day Public Education

    ERIC Educational Resources Information Center

    Meabon Bartow, Susan

    2014-01-01

    Because social technologies present illuminating educational, ethical, economic, and structural challenges to existing constructions of public education, they catalyze a fundamental examination of what public education should look like and be like in a democracy. Given their performances in other arenas, mobile and electronic technologies have the…

  11. The ethical debate on present day paternity testing practices.

    PubMed

    Mertens, G

    2006-01-01

    The last years, the number of paternity tests on buccal swabs sold over the internet as "test kits", has steeply increased. The commercial providers of these services facilitate controversial practices, including clandestine sampling at home, anonymous sending off for analysis, motherless testing and using "stolen" personal objects containing biological material (combs, cigarette butts). This has led to concern on the consequences on the family unit--especially the child--which may suffer emotionally, physically and financially. In reaction, legal initiatives are appearing throughout Europe. The UK Human Genetics Commission has advised that the non-consensual obtaining and analysis of personal genetic information should be a new criminal offence. The German Federal Court of Justice has ruled that paternity tests performed without the mother's knowledge are inadmissible as evidence in lawsuits. French law strictly forbids the application of DNA testing without the involvement of the court system. In Belgium, a proposal for law has been laid down where the offering to PMID:16792338

  12. Tracing galaxy evolution by their present-day luminosity function

    NASA Astrophysics Data System (ADS)

    Tempel, Elmo

    2011-04-01

    Galaxies, which are complex objects containing up to several tens of billions stars, as well as gas and dust, are remarkable objects. The Universe contains a very diverse "zoo" of galaxies: there are galaxies with a discy shape and spiral structure, elliptical galaxies, and even galaxies, which show no sign of structure. This variety of galaxies leads to the basic question: how the galaxies form and evolve and which processes shape the structure of galaxies? Due to the complexity of galaxy formation and evolution, this question is still an unresolved puzzle and it is one of the biggest challenges in modern cosmology. The present thesis is based on large galaxy surveys and concentrates on the large-scale structure: how galaxy evolution is related to the surrounding large-scale environment of superclusters and voids. To study the evolution of galaxies, we use the luminosity function, which is in this respect one of the most fundamental of all cosmological observables. One of the principal results of the present study was the conclusion that the evolution of spiral galaxies is almost independent of the global environment, especially for blue and red spirals separately, showing that the formation of spiral galaxies has to be similar in all environments. Meanwhile, the luminosity function of elliptical galaxies depends strongly on the environment. This shows that the global environmental density is an important factor (via merging history) in the formation of elliptical galaxies. The results of the present study show clearly, that besides the local/group environment, the global (supercluster-void) environment plays also an important role in the formation and evolution of galaxies. Accounting for the role of global environment can help to solve several problems in the present picture of galaxy formation and evolution.

  13. QCD relics in the present-day Universe?

    SciTech Connect

    Ribeiro, J. E. F. T.; Antonov, D.; Nefediev, A. V.

    2011-05-23

    A possibility is suggested for the formation in the Universe of domains occupied by coherent-like states of strongly correlated quark-antiquark pairs. Only domains of the radius larger than 5 fm had a chance to survive over the entire history of the Universe, while the requirement of stability against the gravitational collapse restricts the maximum domain's radius to 14 km. Within the Generalised Nambu-Jona-Lasinio model, an exponential suppression with the domain's volume is found for the overlap between the macroscopic ground-state wavefunction of the quark-antiquark pairs and the QCD vacuum. This finding supports, at the microscopic level, the above arguments in favour of the stability of the domains.

  14. Active Immunization—Some Present-Day Problems

    PubMed Central

    1941-01-01

    Diphtheria.—Immunization is safe and effective. Compulsory measures are indicated, especially for the younger age-groups. The Schick test may be reserved for selected groups and to control modified methods. Proper spacing of doses of prophylactics and periodic reinoculation will ensure a high level of immunity. It is important to beware of “one-shot” methods. Indiscriminate swabbing is to be discouraged; high carrier rates are an indication for widespread diphtheria prophylaxis. Enteric fever.—Mass immunization is desirable in many areas, although there is no justification for compulsion except for people exposed to special risks. In deciding upon dosage of vaccine, more attention should be paid to physical state and body-weight. After the primary course, very small periodic doses (for example o.i.c.c) are worthy of trial. Vaccine can be given during an epidemic without increasing the chances of infection. Tetanus.—Two doses of toxoid spaced by six weeks give useful immunity. Women give significantly higher titres than men. A third dose of i.o.c.c. after a long interval—seven to nine months—often produces a dramatic rise in circulating antitoxin, and counteracts any tendency to waning immunity. Smallpox.—As vaccination has not been made compulsory in this country, infection by virulent strains from the continent may tax the resources of the public health services. Whooping-cough.—The large number of injections of vaccine usually recommended is a deterrent to mass immunization. Research into the possibility of fewer doses and wider spacing is indicated. Other diseases are considered briefly. Combined immunization.—It may be useful to combine diphtheria T.A.F. and tetanus toxoid, also tetanus toxoid and T.A.B. vaccine. T.A.F. plus T.A.B. is probably contra-indicated for adults on account of severe reactions. Diphtheria A.P.T. should not be mixed with tetanus toxoid as it may go into solution and become ineffective. Sterilization of syringes and needles.—An intensive inoculation campaign is no excuse for slip-shod methods. PMID:19992328

  15. Present-day anthelmintics and perspectives on future new targets.

    PubMed

    Taman, Amira; Azab, Manar

    2014-07-01

    In absence of vaccines for the majority of helminths, chemotherapy is still the mainstay for controlling human helminthiases. However, a limited number of drugs are available in the market to combat parasitic helminths in human. Besides, the development and spread of drug resistance have declined the use of most currently available anthelmintics. Clearly, availability of new anthelmintic agents will be essential in the next few years. More research into the mechanisms of drug actions and their targets are eminent for the discovery and development of novel anthelmintic agents. Recent drug discovery techniques mostly rely on mechanism-based screening of compounds on heterologously expressed targets in bacterial, mammalian or yeast cells. Although this is usually a successful approach, it is money- and time-consuming; meanwhile, pharmaceutical companies prefer the tested target that is chosen based on basic research. The nervous system is the site of action of several chemotherapeutics including pesticides and antinematode drugs; accordingly, the nervous system continues to be a promising target. Recent advances in exploring helminths' nervous system, neurotransmitters and receptors have paved the way for the development of potential agents targeting the nervous system and its components. PMID:24894082

  16. Present-day uplift of the western Alps

    PubMed Central

    Nocquet, J.-M.; Sue, C.; Walpersdorf, A.; Tran, T.; Lenôtre, N.; Vernant, P.; Cushing, M.; Jouanne, F.; Masson, F.; Baize, S.; Chéry, J.; van der Beek, P. A.

    2016-01-01

    Collisional mountain belts grow as a consequence of continental plate convergence and eventually disappear under the combined effects of gravitational collapse and erosion. Using a decade of GPS data, we show that the western Alps are currently characterized by zero horizontal velocity boundary conditions, offering the opportunity to investigate orogen evolution at the time of cessation of plate convergence. We find no significant horizontal motion within the belt, but GPS and levelling measurements independently show a regional pattern of uplift reaching ~2.5 mm/yr in the northwestern Alps. Unless a low viscosity crustal root under the northwestern Alps locally enhances the vertical response to surface unloading, the summed effects of isostatic responses to erosion and glaciation explain at most 60% of the observed uplift rates. Rock-uplift rates corrected from transient glacial isostatic adjustment contributions likely exceed erosion rates in the northwestern Alps. In the absence of active convergence, the observed surface uplift must result from deep-seated processes. PMID:27346228

  17. Satellite galaxies around present-day massive ellipticals

    NASA Astrophysics Data System (ADS)

    Ruiz, Pablo; Trujillo, Ignacio; Mármol-Queraltó, Esther

    2014-07-01

    Using the spectroscopic New York University Value-Added Galaxy Catalogue and the photometric photo-z catalogues of the Sloan Digital Sky Survey Data Release 7, we have explored the satellite distribution around ˜1000 massive (M⋆ ≳ 2 × 1011 M⊙) visually classified elliptical galaxies down to a satellite mass ratio of 1:400 (i.e. 5 × 108 ≲ Msat ≲ 2 × 1011 M⊙). Our host galaxies were selected to be representative of a mass complete sample. The satellites of these galaxies were searched within a projected radial distance of 100 kpc to their hosts. We have found that only 20-23 per cent of the massive ellipticals have at least a satellite down to a mass ratio 1:10. This number increases to 45-52 per cent if we explore satellites down to 1:100 and is >60-70 per cent if we go further down to 1:400. The average projected radial distance of the satellites to their hosts for our whole sample down to 1:400 is ˜59 kpc (which can be decreased at least down to 50 kpc if we account for incompleteness effects). The number of satellites per galaxy host only increases very mildly at decreasing the satellite mass. The fraction of mass which is contained in the satellites down to a mass ratio of 1:400 is 8 per cent of the total mass contained by the hosts. Satellites with a mass ratio from 1:2 to 1:5 (with ˜28 per cent of the total mass of the satellites) are the main contributor to the total satellite mass. If the satellites eventually infall into the host galaxies, the merger channel will be largely dominated by satellites with a mass ratio down to 1:10 (as these objects have 68 per cent of the total mass in satellites).

  18. A comparative study of prebiotic and present day translational models

    NASA Technical Reports Server (NTRS)

    Rein, R.; Raghunathan, G.; Mcdonald, J.; Shibata, M.; Srinivasan, S.

    1986-01-01

    It is generally recognized that the understanding of the molecular basis of primitive translation is a fundamental step in developing a theory of the origin of life. However, even in modern molecular biology, the mechanism for the decoding of messenger RNA triplet codons into an amino acid sequence of a protein on the ribosome is understood incompletely. Most of the proposed models for prebiotic translation lack, not only experimental support, but also a careful theoretical scrutiny of their compatibility with well understood stereochemical and energetic principles of nucleic acid structure, molecular recognition principles, and the chemistry of peptide bond formation. Present studies are concerned with comparative structural modelling and mechanistic simulation of the decoding apparatus ranging from those proposed for prebiotic conditions to the ones involved in modern biology. Any primitive decoding machinery based on nucleic acids and proteins, and most likely the modern day system, has to satisfy certain geometrical constraints. The charged amino acyl and the peptidyl termini of successive adaptors have to be adjacent in space in order to satisfy the stereochemical requirements for amide bond formation. Simultaneously, the same adaptors have to recognize successive codons on the messenger. This translational complex has to be realized by components that obey nucleic acid conformational principles, stabilities, and specificities. This generalized condition greatly restricts the number of acceptable adaptor structures.

  19. Human Capital and Its Development in Present-Day Russia

    ERIC Educational Resources Information Center

    Nureev, R. M.

    2010-01-01

    In the broad sense of the word human capital is a specific form of capital that is embodied in people themselves. It consists of the individual's reserve of health, knowledge, skills, abilities, and motivations that enable him to increase his labor productivity and give him an income in the form of wages, salaries, and other income. The structure…

  20. Syphilis: An Old Disease With Present-Day Implications.

    PubMed

    McNeil, Candice J; Bachmann, Laura H

    2016-01-01

    Syphilis continues to be a burden on the public health system. While men who have sex with men and HIV-infected individuals are the most affected populations, syphilis rates have also increased in reproductive-aged women, resulting in concurrent increases in congenital syphilis. Prompt diagnosis and treatment are requisite components of syphilis control. PMID:27621352

  1. Illiteracy, Sex and Occupational Status in Present-Day China.

    ERIC Educational Resources Information Center

    Lamontagne, Jacques

    This study determined the magnitude of disparity between men and women in China in relation to illiteracy and occupational status. Region and ethnicity are used as control variables. The data collected are from a 10 percent sampling of the 1982 census; the total sample size includes a population of 100,380,000 nationwide. The census questionnaire…

  2. Catalogues of variable stars from Parenago to the present day

    NASA Astrophysics Data System (ADS)

    Samus, N. N.

    2006-04-01

    After World War II, the International Astronomical Union made Soviet astronomers responsible for variable-star catalogues. This work has been continued ever since the first edition of the General Catalogue of Variable Stars compiled by the team headed by P.P. Parenago and B.V. Kukarkin and published in 1948. Currently, the catalogue work is a joint project of the Institute of Astronomy (Russian Academy of Sciences) and the Sternberg Astronomical Institute (Moscow University). This paper is a brief review of recent trends in the field of variable-star catalogues. Problems as well as new prospects related to modern large-scale automatic photometric sky surveys are discussed.

  3. Present-day uplift of the western Alps.

    PubMed

    Nocquet, J-M; Sue, C; Walpersdorf, A; Tran, T; Lenôtre, N; Vernant, P; Cushing, M; Jouanne, F; Masson, F; Baize, S; Chéry, J; van der Beek, P A

    2016-01-01

    Collisional mountain belts grow as a consequence of continental plate convergence and eventually disappear under the combined effects of gravitational collapse and erosion. Using a decade of GPS data, we show that the western Alps are currently characterized by zero horizontal velocity boundary conditions, offering the opportunity to investigate orogen evolution at the time of cessation of plate convergence. We find no significant horizontal motion within the belt, but GPS and levelling measurements independently show a regional pattern of uplift reaching ~2.5 mm/yr in the northwestern Alps. Unless a low viscosity crustal root under the northwestern Alps locally enhances the vertical response to surface unloading, the summed effects of isostatic responses to erosion and glaciation explain at most 60% of the observed uplift rates. Rock-uplift rates corrected from transient glacial isostatic adjustment contributions likely exceed erosion rates in the northwestern Alps. In the absence of active convergence, the observed surface uplift must result from deep-seated processes. PMID:27346228

  4. Present-day plate motions. [ocean bottom movements

    NASA Technical Reports Server (NTRS)

    Minster, J. B.; Jordan, T. H.

    1978-01-01

    An instantaneous plate-motion model, Relative Motion 2 (RM2), is obtained by inverting a data set comprising 110 spreading rates, 78 transform fault azimuths, and 142 earthquake slip vectors. RM2 is compared with angular velocity vectors which best fit the data along individual plate boundaries and, while the model performs close to optimally in most regions, attention is directed to those regions which are not suitably described by the model. Reasons for the discrepancies between RM2 and observations for the India-Antarctica plate boundary, the Pacific-India plate boundary, and the east-west trending transform fault azimuths observed in the French-American Mid-Ocean Undersea Study area are discussed.

  5. Microplate model for the present-day deformation of Tibet

    USGS Publications Warehouse

    Thatcher, W.

    2007-01-01

    Site velocities from 349 Global Positioning System (GPS) stations are used to construct an 11-element quasi-rigid block model of the Tibetan Plateau and its surroundings. Rigid rotations of five major blocks are well determined, and average translation velocities of six smaller blocks can be constrained. Where data are well distributed the velocity field can be explained well by rigid block motion and fault slip across block boundaries. Residual misfits average 1.6 mm/yr compared to typical one standard deviation velocity uncertainties of 1.3 mm/yr. Any residual internal straining of the blocks is small and heterogeneous. However, residual substructure might well represent currently unresolved motions of smaller blocks. Although any smaller blocks must move at nearly the same rate as the larger blocks within which they lie, undetected relative motions between them could be significant, particularly where there are gaps in GPS coverage. Predicted relative motions between major blocks agree with the observed sense of slip and along-strike partitioning of motion across major faults. However, predicted slip rates across Tibet's major strike-slip faults are low, only 5-12 mm/yr, a factor of 2-3 smaller than most rates estimated from fault offset features dated by radiometric methods as ???2000 to ???100,000 year old. Previous work has suggested that both GPS data and low fault slip rates are incompatible with rigid block motions of Tibet. The results reported here overcome these objections.

  6. Mammalian phylogeny reveals recent diversification rate shifts.

    PubMed

    Stadler, Tanja

    2011-04-12

    Phylogenetic trees of present-day species allow investigation of the rate of evolution that led to the present-day diversity. A recent analysis of the mammalian phylogeny challenged the view of explosive mammalian evolution after the Cretaceous-Tertiary (K/T) boundary (65 Mya). However, due to lack of appropriate methods, the diversification (speciation minus extinction) rates in the more recent past of mammalian evolution could not be determined. In this paper, I provide a method that reveals that the tempo of mammalian evolution did not change until ∼ 33 Mya. This constant period was followed by a peak of diversification rates between 33 and 30 Mya. Thereafter, diversification rates remained high and constant until 8.55 Mya. Diversification rates declined significantly at 8.55 and 3.35 Mya. Investigation of mammalian subgroups (marsupials, placentals, and the six largest placental subgroups) reveals that the diversification rate peak at 33-30 Mya is mainly driven by rodents, cetartiodactyla, and marsupials. The recent diversification rate decrease is significant for all analyzed subgroups but eulipotyphla, cetartiodactyla, and primates. My likelihood approach is not limited to mammalian evolution. It provides a robust framework to infer diversification rate changes and mass extinction events in phylogenies, reconstructed from, e.g., present-day species or virus data. In particular, the method is very robust toward noise and uncertainty in the phylogeny and can account for incomplete taxon sampling. PMID:21444816

  7. Revealing Mercury

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Solomon, S. C.; Head, J. W.; Watters, T. R.; Murchie, S. L.; Robinson, M. S.; Chapman, C. R.; McNutt, R. L.

    2009-04-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, launched in August 2004. En route to insertion into orbit about Mercury in 2011, MESSENGER flies by Mercury three times. The first and second of these encounters were accomplished in January and October of 2008. These flybys viewed portions of Mercury's surface that were not observed by Mariner 10 during its reconnaissance of somewhat less than half of the planet in 1974-1975. All MESSENGER instruments operated during each flyby and returned a wealth of new data. Many of the new observations were focused on the planet's geology, including monochrome imaging at resolutions as high as 100 m/pixel, multispectral imaging in 11 filters at resolutions as high as 500 m/pixel, laser altimetry tracks extending over several thousands of kilometers, and high-resolution spectral measurements of several types of terrain. Here we present an overview of the first inferences on the global geology of Mercury from the MESSENGER observations. Whereas evidence for volcanism was equivocal from Mariner 10 data, the new MESSENGER images and altimetry provide compelling evidence that volcanism was widespread and protracted on Mercury. Color imaging reveals three common spectral units on the surface: a higher-reflectance, relatively red material occurring as a distinct class of smooth plains, typically with distinct embayment relationships interpreted to indicate volcanic emplacement; a lower-reflectance, relatively blue material typically excavated by impact craters and therefore inferred to be more common at depth; and a spectrally intermediate terrain that constitutes much of the uppermost crust. Three more minor spectral units are also seen: fresh crater ejecta, reddish material associated with rimless depressions interpreted to be volcanic centers, and high-reflectance deposits seen in some crater floors. Preliminary measurements of crater size

  8. How Are Preferences Revealed?

    PubMed Central

    Beshears, John; Choi, James J.; Laibson, David; Madrian, Brigitte C.

    2009-01-01

    Revealed preferences are tastes that rationalize an economic agent’s observed actions. Normative preferences represent the agent’s actual interests. It sometimes makes sense to assume that revealed preferences are identical to normative preferences. But there are many cases where this assumption is violated. We identify five factors that increase the likelihood of a disparity between revealed preferences and normative preferences: passive choice, complexity, limited personal experience, third-party marketing, and intertemporal choice. We then discuss six approaches that jointly contribute to the identification of normative preferences: structural estimation, active decisions, asymptotic choice, aggregated revealed preferences, reported preferences, and informed preferences. Each of these approaches uses consumer behavior to infer some property of normative preferences without equating revealed and normative preferences. We illustrate these issues with evidence from savings and investment outcomes. PMID:24761048

  9. Present-day groundwater recharge estimation in parts of the Indian Sub-Continent

    NASA Astrophysics Data System (ADS)

    Bhanja, S. N.; Mukherjee, A.; Wada, Y.; Scanlon, B. R.; Taylor, R. G.; Rodell, M.; Malakar, P.

    2015-12-01

    Large part of global population has been dependent on groundwater as a source of fresh water. The demand would further increase with increasing population and stress associated with climate change. We tried to provide regional-scale groundwater recharge estimates in a large part of Indian Sub-Continent. A combination of ground-based, satellite-based and numerical model simulated recharge estimates were presented in the densely populated region. Three different methods: an intense network of observational wells (n>13,000 wells), a satellite (TRMM) and global land-surface model (CLM) outputs, and a global-scale hydrological model (PCR GLOBWB) were employed to calculate recharge estimates. Groundwater recharge values exhibit large spatial variations over the entire region on the basis of aquifer hydrogeology, precipitation and groundwater withdrawal patterns. Groundwater recharge estimates from all three estimation techniques were found to be higher (>300 mm/year) in fertile planes of Indus-Ganges-Brahmaputra (IGB) river basins. A combination of favorable hydrogeologic conditions (porosity, permeability etc.), comparatively higher rates of precipitation, and return flow from rapidly withdrawn irrigation water might influence occurrence of high recharge rates. However, central and southern study area experiences lower recharge rates (<200 mm/year), might be associated with unfavorable hydrogeologic conditions associated with cratonic provinces. Statistical analysis of inter-comparison between the three different recharge estimates show good matches in some of the areas. Recharge estimates indicate dynamic nature of groundwater recharge as a function of precipitation, land use pattern, and hydrogeologic parameters. On a first hand basis, the estimates will help policy makers to understand groundwater recharge process over the densely populated region and finally would facilitate to implement sustainable policy for securing water security.

  10. Modeling Greenland ice sheet present-day and near-future runoff contribution.

    NASA Astrophysics Data System (ADS)

    Peano, Daniele; Colleoni, Florence; Masina, Simona

    2014-05-01

    The last IPCC report [AR5, IPCC] has shown an increasing contribution from Greenland melting to global sea-level over the last decade, increasing from 0.09 mm/year (period 1992-2001) to 0.59 mm/year (period 2002-2011). Given its strategic location, i.e. close to the main North Atlantic ocean convection sites, it is therefore of importance to better assess ice sheet melting and its impact on regional ocean processes. So far, runoff estimate from ice sheet has been poorly constrained (e.g. [Hanna et al., 2005], [Hanna et al., 2008]) and most of the time the few estimates comes from regional atmospheric models or general circulation models (e.g. [Edwards et al., 2013], [Fettweis et al., 2013]). Here, we present the results from the implementation of a routing scheme into the thermo-mechanical ice sheet-ice shelves model GRISLI [Ritz et al, 2001], applied to the Greenland ice sheet mass evolution over the 20th and 21st centuries. The routing scheme is based on the "multiple flow direction" developed by [Quinn et al., 1991]. We further improved this scheme by considering topographic depressions as possible "lakes" to be filled by meltwater. In this way, when a depression is filled, only the extra water is routed towards the Greenland coasts. This allow us to obtain an estimate of the total amount of freshwater reaching the ocean at each time step of the model integration, as well as a time-varying spatial distribution of the runoff along the coasts of Greenland. This routing scheme is applied in routing both surface and basal meltwater. Surface meltwater is computed by means of a PDD method [Fausto et al., 2007] on which only a fraction is considered for routing while the basal melting rate is part of the heat balance at the ice-bed interface. Runoff is simulated on a 5km x 5km horizontal grid and validation is performed over the 20th century using mean annual total precipitation and air temperature at 2 meters from Era-Interim reanalysis [Dee et al., 2011]. Near future projections are then computed using the climate forcing from CMCC 21st century CMIP5 simulations (RCP 8.5 and RCP 4.5). Since the results could be dependent on the ice dynamics and on the surface mass balance method, the runoff scheme is also implemented in the land-based model SICOPOLIS [Greve, 1995] and results are compared to those obtained with GRISLI.