9 research outputs found

    Paleomagnetism and astronomically induced cyclicity of the Armantes section; a Miocene continental red sequence in the Calatayud-Daroca basin (Central Sapin)

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    The Armantes section is a red-bed sequence consisting of a regular altemation (10 m scale) of reddish silts and pink/white limestones.In between these limestones, a smaller-scale bedding (2-3 m scale) is intercalated, characterised by varying carbonate content and related differences in erosion resistance. An earlier correlation of the magnetic polarity sequence of the Armantes section to the geomagnetic polarity time scale (GPTS) suggested a periodicity of 111 kyr for the large-scale cyclicity (Krijgsman et al., 1994b). The carbonate, gamma-ray and susceptibility records indicate that 4 to 5 small-scale cycles are developed in one large-scale cycle, showing that the small-scale cyclicity is related to precession and thus caused by climate forcing. We suggest that the precipitation of the carbonates is most likely related to rising ground-water levels and an increase of evaporation. This implies that the thick limestone beds would correlate to eccentricity maxima and the smaller-scale limestone beds to precession minima. Rock magnetic experiments show that the NRM in the Armantes section results from the presence of hematite and magnetite/maghemite.The relative contribution of hematite is strongly related to the lithology. Hematite is the dominant carrier in the limestones, while in the silts magnetite/maghemite prevail

    Paleomagnetism and astronomically induced cyclicity of the Armantes section; a Miocene continental red sequence in the Calatayud-Daroca basin (Central Sapin)

    Get PDF
    The Armantes section is a red-bed sequence consisting of a regular altemation (10 m scale) of reddish silts and pink/white limestones.In between these limestones, a smaller-scale bedding (2-3 m scale) is intercalated, characterised by varying carbonate content and related differences in erosion resistance. An earlier correlation of the magnetic polarity sequence of the Armantes section to the geomagnetic polarity time scale (GPTS) suggested a periodicity of 111 kyr for the large-scale cyclicity (Krijgsman et al., 1994b). The carbonate, gamma-ray and susceptibility records indicate that 4 to 5 small-scale cycles are developed in one large-scale cycle, showing that the small-scale cyclicity is related to precession and thus caused by climate forcing. We suggest that the precipitation of the carbonates is most likely related to rising ground-water levels and an increase of evaporation. This implies that the thick limestone beds would correlate to eccentricity maxima and the smaller-scale limestone beds to precession minima. Rock magnetic experiments show that the NRM in the Armantes section results from the presence of hematite and magnetite/maghemite.The relative contribution of hematite is strongly related to the lithology. Hematite is the dominant carrier in the limestones, while in the silts magnetite/maghemite prevail

    External validation of a model for periconceptional prediction of recurrent early-onset preeclampsia

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    Objective: To validate a previously published prediction model for recurrent early-onset preeclampsia (PE). Methods: We included 229 pregnant women with a history of early-onset PE and computed their risk using the prediction model, compared the predicted risk to their pregnancy outcomes and assessed performance of the model. Results: Early-onset PE recurred in 6.6% of participants. The area under the receiver operating characteristic curve was 59% (95% CI: 45-73). The model created groups that were only moderately different in terms of their risk. Conclusions: The model's discriminate ability was poor and predictive performance insufficient to classify women into relevant risk groups

    Multicenter impact analysis of a model for predicting recurrent early-onset preeclampsia: A before-after study

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    This study aims to determine the impact of using a prediction model for recurrent preeclampsia to customize antenatal care in subsequent pregnancies. We compared care consumption, pregnancy outcomes, and self-reported health state of two risk-based subgroups, and compared these to a reference group receiving standard care. We included a total of 311 women from 12 hospitals. Compared to standard care, recurrence-risk guided care did not lead to different outcomes or self-perceived health. Our study exemplifies that recurrence-risk-based stratification of antenatal care in former preeclampsia patients is feasible; it does not lead to worse pregnancy outcome

    A model for preconceptional prediction of recurrent early-onset preeclampsia: derivation and internal validation.

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    Contains fulltext : 95573.pdf (publisher's version ) (Closed access)OBJECTIVE: To develop a model to identify women at very low risk of recurrent early-onset preeclampsia. METHODS: We enrolled 407 women who had experienced early-onset preeclampsia in their first pregnancy, resulting in a delivery before 34 weeks' gestation. Preeclampsia was defined as hypertension (systolic blood pressure >/=140 mm Hg and/or diastolic blood pressure >/=90 mm Hg) after 20 weeks' gestation with de novo proteinuria (>/=300 mg urinary protein excretion/day). Based on the previous published evidence and expert opinion, 5 predictors (gestational age at previous birth, prior small-for-gestational-age newborn, fasting blood glucose, body mass index, and hypertension) were entered in a logistic regression model. Discrimination and calibration were evaluated after adjusting for overfitting by bootstrapping techniques. RESULTS: Early-onset disease recurred in 28 (6.9%) of 407 women. The area under the receiver operating characteristic (ROC) curve of the model was 0.65 (95% CI: 0.56-0.74). Calibration was good, indicated by a nonsignificant Hosmer-Lemeshow test (P = .11). Using a predicted absolute risk threshold of, for example, 4.6% (ie, women identified with an estimated risk either above or below 4.6%), the sensitivity was 100%, with a specificity of 26%. In such a strategy, no women who developed preeclampsia were missed, while 98 of the 407 women would be regarded as low risk of recurrent early-onset preeclampsia, not necessarily requiring intensified antenatal care. CONCLUSION: Our model may be helpful in the identification of women at very low risk of recurrent early-onset preeclampsia. Before widespread application, our model should be validated in other populations.1 november 201
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