1,873 research outputs found

    Permeability evolution across carbonate hosted normal fault zones

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    Acknowledgements: The authors would like to thank Total E&P and BG Group for project funding and support, and the Industry Technology Facilitator for facilitating the collaborative development (grant number 3322PSD). The authors would also like to express their gratitude to the Aberdeen Formation Evaluation Society and the College of Physical Sciences at the University of Aberdeen for partial financial support. Raymi Castilla (Total E&P), Fabrizio Agosta and Cathy Hollis are also thanked for their constructive comments and suggestions to improve the standard of this manuscript as are John Still and Colin Taylor (University of Aberdeen) for technical assistance in the laboratory. Piero Gianolla is thanked for his editorial handling of the manuscript.Peer reviewedPostprin

    Navigating inferior vena cava filters in invasive cardiology procedures: A systematic review

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    BACKGROUND: Transfemoral venous access (TFV) is the cornerstone of minimally invasive cardiac procedures. Although the presence of inferior vena cava filters (IVCFs) was considered a relative contraindication to TFV procedures, small experiences have suggested safety. We conducted a systematic review of the available literature on cardiac procedural success of TFV with IVCF in-situ. METHODS: Two independent reviewers searched PubMed, EMBASE, SCOPUS, and Google Scholar from inception to October 2020 for studies that reported outcomes in patients with IVCFs undergoing TFV for invasive cardiac procedures. We investigated a primary outcome of acute procedural success and reviewed the pooled data for patient demographics, procedural complications, types of IVCF, IVCF dwell time, and procedural specifics. RESULTS: Of the 120 studies initially screened, 8 studies were used in the final analysis with a total of 100 patients who underwent 110 procedures. The most common IVCF was the Greenfield Filter (36%), 60% of patients were males and the mean age was 67.8 years. The overall pooled incidence of acute procedural success was 95.45% (95% confidence interval 89.54. - 98.1) with no heterogeneity (I2 = 0%, p = 1) and there were no reported filter related complications. CONCLUSION: This systematic review is the largest study of its kind to demonstrate the safety and feasibility of TFV access in a variety of cardiac procedures in the presence of IVCF

    Use of a regional wall motion score to enhance risk stratification of patients receiving an implantable cardioverter-defibrillator

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    AbstractObjectives. We postulated that preoperative assessment of both regional wall motion and left ventricular ejection fraction would serve as an accurate prognostic indicator of long-term cardiac mortality and functional outcome in patients treated with an implantable cardioverter-defibrillator.Background. Long-term cardiac mortality has remained high in patients receiving an implantable cardioverter-defibrillator. The ability to risk stratify patients before defibrillator implantation is becoming increasingly important from a medical and economic standpoint.Methods. The hypothesis was retrospectively tested in 74 patients who had received an implantable cardioverterdefibrillator. Left ventricular ejection fraction and regional wall motion score, derived from centerline chord motion analysis, were calculated for each patient from the preoperative right anterior oblique contrast ventriculogram. Wall motion score was the only significant independent predictor of long-term cardiac mortality and functional status by multivariate analysis because of its enhanced prognostic capability in patients with an ejection fraction in the critical range of 30% to 40%.Results. Patients with an ejection fraction >40% had a 3-year cardiac mortality rate of 0% compared with 25% for those with an ejection fraction of 30% to 40% and 48% for those with an ejection fraction <30% (p < 0.05). Similarly, 75% of patients with an ejection fraction >40% were in New York Heart Association functional class I or II during long-term follow-up compared with 59% of those with an ejection fraction 30% to 40% and 29% of those with an ejection fraction <30%. Among patients with an ejection fraction of 30% to 40%, those with a wall motion score >16% had a 3-year cardiac mortality rate of 0% compared with 71% of those with a wall motion score ≤ 16% (p = 0.002). In addition, 86% of patients with a wall motion score >16% were in functional class I or II during long-term follow-up compared with 13% of those with a wall motion score ≤16% (p = 0.001).Conclusions. Long-term cardiac mortality and functional outcome in patients receiving an implantable cardioverterdefibrillator can be predicted if the left ventricular ejection fraction and regional wall motion score are measured preoperatively

    Upper Kellwasser carbon isotope excursion pre-dates the F–F boundary in the Upper Devonian Lennard shelf carbonate system, Canning Basin, Western Australia

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    Here we report four high-resolution carbon isotope records in addition to trace element data for the Frasnian–Famennian (F–F) boundary interval in the Lennard Shelf carbonate system of the Canning Basin, Western Australia. This region lacks the characteristic black shale horizons associated with the global Late Devonian Kellwasser extinction events, yet still exhibits a trend in carbon isotope character similar to what has been reported from elsewhere in the world (two positive δ13C excursions with ~3–4‰ amplitudes). Enrichments in select trace element ratios suggest that both excursions are related to periods of oxygen deprivation and perhaps increased biological productivity. Given the continuous and stratigraphically expanded nature of Lennard Shelf sections, together with high-density sampling constrained by both conodont biostratigraphy and magnetostratigraphy, we observe that the Upper Kellwasser isotope excursion (maximum δ13C values) and associated trace element enrichments occur distinctly lower than the F–F boundary level. These results have implications for the paleoenvironmental conditions leading up to the Late Devonian Mass Extinction in terms of ocean chemistry and circulation patterns. This data set allows for a rare, detailed look at the temporal relationship between the Kellwasser events and the F–F boundary and constrains the pattern of carbon isotope perturbations at the intra-zonal scale

    Using elemental chemostratigraphy on Mid-Late Frasnian platform-top successions from the Lennard Shelf outcrops, Canning Basin, Western Australia.

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    High-resolution chronostratigraphic correlation using elemental chemostratigraphy in platform carbonates is typically difficult to achieve. Here, elemental chemostratigraphy is used to correlate between two platform-top, carbonate-dominated field sections from the narrow Lennard Shelf that existed on the NE margin of the Canning Basin, Western Australia, during the mid–late Frasnian. The correlation, constrained by magnetic polarity reversals and physical ground truthing, is based on recognition of distinctive cyclical ‘‘stacking patterns’’ defined by changes in concentrations of the trace element zirconium (Zr). Zr concentrations are controlled by the amount of the heavy mineral zircon in the sediments, which is derived from a terrigenous source and is diagenetically very stable. The stacking patterns in the lower part of the study sections display gradually upward-increasing values of Zr to a maximum, followed by an almost immediate fall to a minimum. In the upper part of the study interval, the cycles are more symmetrical, with both gradually increasing and decreasing portions. The point at which the change in Zr stacking pattern occurs in the two sections is synchronous and occurs in association with a supersequence maximum flooding surface. The correlation based on maximum and minimum Zr values throughout the two sections is demonstrated to be chronostratigraphic by comparison with correlations based upon paleomagnetism and physical ground truthing. When element ratios commonly used as provenance and paleoclimate proxies are plotted, the variations between closely spaced samples are greater than any systematic variations throughout the study intervals. Therefore, no isochemical chemozones can be defined, implying that during deposition of the study intervals, there were no long-lived changes in sediment provenance or paleoclimate that the elemental chemistry can detect. The work presented here shows that the standard approach of defining isochemical chemozones for chemostratigraphic correlation is not always appropriate. However, an approach using cyclical changes in elemental variables for chemostratigraphic correlation between two closely spaced sections is chronostratigraphically valid. The greater challenge is in application of the same approach to more widely spaced sections, potentially in different facies of a carbonate setting

    Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z~0.2

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    An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT) to measure the 12^{12}CO J = 1 --> 0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N\geq3.6) of the 12^{12}CO line, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eight targets we can place upper limits on molecular gas masses roughly between 10910^9 and 1010M10^{10} M_\odot. Comparing our results to other studies of molecular gas, we find that our sample is significantly more abundant in molecular gas overall, when compared to the stellar and the atomic gas component, and our median molecular gas fraction lies about 1σ1\sigma above the upper limits of proposed redshift evolution in earlier studies. We discuss possible reasons for this discrepancy, with the most likely conclusion being target selection and Eddington bias.Comment: MNRAS, submitte

    LoCuSS: Luminous infrared galaxies in the merging cluster Abell 1758 at z=0.28

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    We present the first galaxy evolution results from the Local Cluster Substructure Survey (LoCuSS), a multi-wavelength survey of 100 X-ray selected galaxy clusters at 0.15<z<0.30. LoCuSS combines far-UV through far-IR observations of cluster galaxies with gravitational lensing analysis and X-ray data to investigate the interplay between the hierarchical assembly of clusters and the evolution of cluster galaxies. Here we present new panoramic Spitzer/MIPS 24micron observations of the merging cluster Abell 1758 at z=0.279 spanning 6.5x6.5Mpc and reaching a 90% completeness limit of 400uJy. We estimate a global cluster SFR of 910\pm320 M_sun/yr within 3 Mpc of the cluster centre, originating from 42 galaxies with L_IR > 5x10^10 L_sun. The obscured activity in A1758 is therefore comparable with that in Cl 0024+1654, the most active cluster previously studied at 24um. The obscured galaxies faithfully trace the cluster potential as revealed by the weak-lensing mass map of the cluster, including numerous mass peaks at R~2-3Mpc that are likely associated with infalling galaxy groups and filamentary structures. However the core (R<500kpc) of A1758N is 2x more active in the IR than that of A1758S, likely reflecting differences in the recent dynamical history of the two clusters. The 24micron results from A1758 therefore suggest that dust-obscured cluster galaxies are common in merging clusters and suggests that obscured activity in clusters is triggered by both the details of cluster-cluster mergers and processes that operate at larger radii including those within in-falling groups. Our ongoing far-UV through far-IR observations of a large sample of clusters should allow us to disentangle the different physical processes responsible for triggering obscured star formation in clusters.Comment: 13 pages, 9 figures. Accepted for publication in MNRA
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