163 research outputs found

    The upper cretaceous and lower paleocene of the eastern bogota plateau and llanos thrustbelt, colombia: alternative appraisal to the nomenclature and sequence stratigraphy

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    EI registro estratigratico de la parte oriental de la Saban a de Bogota y el Piedemonte L1anero ha sido estudiado con base en columnas estratigraticas y pozos petroleros, 10 cual ha conducido a un esquema alternative de nomenclatura estratiqratica y de estratigrafia secuencial. La Forrnacion Chipaque (Cenomaniense-Campaniense) est a suprayacida por el Grupo Guadalupe en la Saban a de Bogota y por el Grupo Palmichal en la zona del Piedemonte L1anero. De base a tope la correlacion entre las formaciones de estos grupos se propone asi: La Forrnacion Arenisca Dura (Campaniense) del Grupo Guadalupe corresponde a la Forrnacion Arenitas de San Antonio del Grupo Palmichal; la Forrnacion Plaeners (Campaniense-Maastrichtiense) a la Forrnacion Lodolitas de Aguacaliente. La Forrnacion Arenisca de Labor, el lIamado nivel de "Lutitas y areniscas finas" y la Forrnacion Arenisca Tierna del Grupo Guadalupe correspond en a la Forrnacion Arenitas de San Luis de Gaceno del Grupo Palmichal. Una parte de la porcion inferior de la Formacion Guaduas de la Sabana de Bogota es equivalente ala Formacion Guaduas del Grupo Palmichal. EI Grupo Palmichal se redefine excluyendo a la Forrnacion Socha Inferior, principalmente por existir una discordancia en su limite inferior, y se incluyen en el las Formaciones anteriormente mencionadas. Los ambientes deposicionales varian de acuerdo a los cambios del nivel del mar, tanto de segundo como de tercer orden. La Forrnacion Chipaque en la Sabana de Bogota representa un (super)cicio de segundo orden que comprende por 10 menos cuatro secuencias de tercer orden. De manera similar, el Grupo Guadalupe y la Forrnacion Guaduas son supersecuencias, en las cuales otras secuencias de mayor frecuencia se pueden delinear. Un periodo de erosion mayor, documentado aqui en el pozo Medina-Ilia causado perdida parcial del registro del piso Maastriclltiense. La siguiente secuencia esta representada en su parte inferior par un sistema de nivel ba]o, dentro de la Formaci6n Socha Inferior.The Upper Cretaceous stratigraphic record of the Eastern Bogota Plateau and Llanos Thrustbelt of Colombia was studied in several outcrop sections and oil wells, leading to an alternative scheme of stratigraphic nomenclature and sequence stratigraphic interpretation. The Chipaque Formation (Cenomanian-Campanian) is overlain by the Guadalupe Group in the Bogota Plateau and by the Palmichal Group in the Llanos Thrustbelt. From oldest to youngest, the correlation between the subdivisions of these two groups is as follows: The Arenisca Dura Formation (Campanian) of the Guadalupe Group, corresponds to the Arenitas de San Antonio Formation of the Palmichal Group; the Plaeners Formation (Campanian-Maastrichtian) to the Lodolitas de Aguacaliente Formation; the Arenisca de Labor, the so-called "Lutitas y areniscas finas" and the Arenisca Tlerna Formations of the Guadalupe Group correspond to the Arenitas de San Luis de Gaceno Formation of the Palmichal Group. In turn, a lower part of the Guaduas Formation of the Bogota Plateau is equivalent to the Guaduas Formation of the Palmichal Group. The Palmichal Group is redefined by excluding the overlying Socha Inferior Formation from it, mainly because the Socha Inferior's lower limit is represented in some places by an unconformity. Additionally, the above mentioned formations are included now in the Palmichal Group. Major depositional environments shift according to sea level fluctuations of second and third order. The Chipaque Formation of the Bogota area is a second order (super)cycie where at least four third order sequences are circumscribed. Likewise, the Guadalupe Group and the Guaduas Formation aresupersequences that bear higher frequency sequences. A major erosion period, documented here in the Medina-1 well, cannibalized part of the Maastrichtian of the Palmichal Group. The youngest sequence studied is represented in its lower portion by the lowstand deposits of the Socha Inferior Formation

    Developmental Analysis of Mimulus Seed Transcriptomes Reveals Functional Gene Expression Clusters and Four Imprinted, Endosperm-Expressed Genes

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    The double fertilization of the female gametophyte initiates embryogenesis and endosperm development in seeds via the activation of genes involved in cell differentiation, organ patterning, and growth. A subset of genes expressed in endosperm exhibit imprinted expression, and the correct balance of gene expression between parental alleles is critical for proper endosperm and seed development. We use a transcriptional time series analysis to identify genes that are associated with key shifts in seed development, including genes associated with secondary cell wall synthesis, mitotic cell cycle, chromatin organization, auxin synthesis, fatty acid metabolism, and seed maturation. We relate these genes to morphological changes in Mimulus seeds. We also identify four endosperm-expressed transcripts that display imprinted (paternal) expression bias. The imprinted status of these four genes is conserved in other flowering plants, suggesting that they are functionally important in endosperm development. Our study explores gene regulatory dynamics in a species with ab initio cellular endosperm development, broadening the taxonomic focus of the literature on gene expression in seeds. Moreover, it is the first to validate genes with imprinted endosperm expression in Mimulus guttatus, and will inform future studies on the genetic causes of seed failure in this model system

    A quality of service assessment technique for large-scale management of multimedia flows

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-540-75869-3_15Proceedings of 10th IFIP/IEEE International Conference on Management of Multimedia and Mobile Networks and Services, MMNS 2007, San José, USA, October 31 - November 2, 2007This paper presents the concept and preliminary experiments of a system for assessing on the Quality of Service of multimedia flows. The goal is to devise a mechanism that allows a service provider to take action whenever poor quality of service is detected in the delivery of multimedia flows. Such procedure is fully automatic since it is based on a goodness-of-fit test between source and destination packet interarrival histograms. If the null hypothesis of the test is accepted the flow is marked as in good standing, otherwise it is marked as anomalous and the network management system should take action in response. The proposed technique is analyzed in terms of hardware complexity and bandwidth consumption. The results show this technique is feasible and easily deployable at a minimum hardware and bandwidth expense.The authors would like to acknowledge the support of the Comunidad Autónoma de Madrid to this work, under project e-Magerit (S-0505/TIC/000251)

    Loop Variables for compact two-dimensional quantum electrodynamics

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    Variables parametrized by closed and open curves are defined to reformulate compact U(1) Quantum Electrodynamics in the circle with a massless fermion field. It is found that the gauge invariant nature of these variables accommodates into a regularization scheme for the Hamiltonian and current operators that is specially well suited for the study of the compact case. The zero mode energy spectrum, the value of the axial anomaly and the anomalous commutators this model presents are hence determined in a manifestly gauge invariant manner. Contrary to the non compact case, the zero mode spectrum is not equally spaced and consequently the theory does not lead to the spectrum of a free scalar boson. All the states are invariant under large gauge transformations. In particular, that is the case for the vacuum, and consequently the θ\theta-dependence does not appear.Comment: 24 pages, 1 figure, to be published in Phys. Rev.

    Non-productive angiogenesis disassembles Aß plaque-associated blood vessels

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    The human Alzheimer’s disease (AD) brain accumulates angiogenic markers but paradoxically, the cerebral microvasculature is reduced around Aß plaques. Here we demonstrate that angiogenesis is started near Aß plaques in both AD mouse models and human AD samples. However, endothelial cells express the molecular signature of non-productive angiogenesis (NPA) and accumulate, around Aß plaques, a tip cell marker and IB4 reactive vascular anomalies with reduced NOTCH activity. Notably, NPA induction by endothelial loss of presenilin, whose mutations cause familial AD and which activity has been shown to decrease with age, produced a similar vascular phenotype in the absence of Aß pathology. We also show that Aß plaque-associated NPA locally disassembles blood vessels, leaving behind vascular scars, and that microglial phagocytosis contributes to the local loss of endothelial cells. These results define the role of NPA and microglia in local blood vessel disassembly and highlight the vascular component of presenilin loss of function in AD

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

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    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

    Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

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    BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

    Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

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    Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe
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