351 research outputs found

    Small scale analysis of population structure in the woody cornelian cherry Cornus mas L. (Cornaceae) by AFLP accentuates the need for a population based conservation strategy

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    We investigated population differentiation among and within three populations (two natural, one artificial) of the cornelian cherry (Cornus mas L., Cornaceae) to examine the extent of gene flow from planted cornelian cherries commonly used in planting vegetations of public parks or streets into natural stands. Additionall we assessed if natural populations show any intrapopulational and/or interpopulational differentiation pointing towards restricted gene flow with possible necessity for a population based conservation strategy rather than a taxon based strategy. Results clearly indicated within and between population structure a radius of isolation by distance for pollen and seed dispersal of about 5.0 km. Interestingly genetic distance did not support coherence of the two natural populations but mirrored the historical origin of the innertown population from diverse natural sources reflecting the traditional use and selection of edible varieties from nature. The Nem value of 1.25 implicates the prevention of population differentation. However the low level of genetic diversity and distance at all might mislead the interpretation and the degree of distance reflects more ancient similarities than actual geneflow. Given this observable isolation by distance, conservation biology of Cornus mas requires a population based strategy rather than a broad taxon based strategy

    Significance of Off-Center Rattling for Emerging Low-lying THz Modes in type-I Clathrates

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    We show that the distinct differences of low-lying THz-frequency dynamics between type-I clathrates with on-center and off-center guest ions naturally follow from a theoretical model taking into account essential features of the dynamics of rattling guest ions. Our model analysis demonstrates the drastic change from the conventional dynamics shown by on-center systems to the peculiar dynamics of off-center systems in a unified manner. We claim that glass-like plateau thermal conductivities observed for off-center systems stem from the flattening of acoustic phonon dispersion in the regime |k|<|G|/4. The mechanism is applicable to other systems such as glasses or relaxers

    A Twisted Ladder: relating the Fe superconductors to the high TcT_c cuprates

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    We construct a 2-leg ladder model of an Fe-pnictide superconductor and discuss its properties and relationship with the familiar 2-leg cuprate model. Our results suggest that the underlying pairing mechanism for the Fe-pnictide superconductors is similar to that for the cuprates.Comment: 5 pages, 4 figure

    The Evolution of Data Fusion Methodologies Developed to Reconstruct Coronary Artery Geometry From Intravascular Imaging and Coronary Angiography Data: A Comprehensive Review

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    Understanding the mechanisms that regulate atherosclerotic plaque formation and evolution is a crucial step for developing treatment strategies that will prevent plaque progression and reduce cardiovascular events. Advances in signal processing and the miniaturization of medical devices have enabled the design of multimodality intravascular imaging catheters that allow complete and detailed assessment of plaque morphology and biology. However, a significant limitation of these novel imaging catheters is that they provide two-dimensional (2D) visualization of the lumen and vessel wall and thus they cannot portray vessel geometry and 3D lesion architecture. To address this limitation computer-based methodologies and user-friendly software have been developed. These are able to off-line process and fuse intravascular imaging data with X-ray or computed tomography coronary angiography (CTCA) to reconstruct coronary artery anatomy. The aim of this review article is to summarize the evolution in the field of coronary artery modeling; we thus present the first methodologies that were developed to model vessel geometry, highlight the modifications introduced in revised methods to overcome the limitations of the first approaches and discuss the challenges that need to be addressed, so these techniques can have broad application in clinical practice and research

    Unguis incarnatus – konservative oder operative Therapie?

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    Unguis incarnatus, an ingrown toenail, is a common condition in primary care, which is encountered by various medical professions. Inconsistent conservative treatment and nonindicated surgical treatment often result in complications and recurrence of the disease. Patients must be thoroughly informed about the complexity of the nail organ. This is a prerequisite to prevent trivialization of the disease and to achieve appropriate patient compliance for treatment. In this article a practical diagnostic and treatment algorithm for unguis incarnatus is presented. In mild cases of acute unguis incarnatus a consistent conservative treatment is the first-line strategy showing promising results. In cases of moderate to severe forms of acute unguis incarnatus, surgical procedures that preserve the nail matrix should be applied. For cases of chronic unguis incarnatus without an acute infection, elective partial matrixectomy can be indicated. Prior to any surgical intervention, detailed informed consent must be obtained from the patients. ZUSAMMENFASSUNG Der Unguis incarnatus ist ein häufiges Krankheitsbild, mit dem sich Patienten in der Hausarztpraxis, der dermatologischen Klinik oder der chirurgischen Notaufnahme vorstellen. Häufig führt die inkonsequente konservative Therapie oder die falsch-indizierte operative Intervention zu langwierigen und komplikationsreichen Verläufen, inklusive Rezidiven. Die Patienten sollten über die Komplexität des Nagelorgans aufgeklärt werden, um der Banalisierung der Erkrankung vorzubeugen, und eine entsprechende Compliance in der Therapie zu erreichen. In diesem Manuskript wird die sachgerechte Versorgung des Unguis incarnatus im Sinne eines praktischen Behandlungsalgorithmus dargestellt. Die konsequente konservative Therapie ist bei akutem Unguis incarnatus mit milder Ausprägung die Therapie der ersten Wahl mit guten Behandlungsergebnissen. Nagelerhaltende operative Eingriffe kommen bei moderaten/schweren akuten Formen zum Einsatz. Der chronische Unguis incarnatus, ohne floride Infektion, stellt eine elektive Operationsindikation dar. Sowohl bei den nagelerhaltenden Eingriffen als auch bei erweiterten operativen Maßnahmen ist eine chirurgische Operationsaufklärung obligat

    Advanced deep learning methodology for accurate, real-time segmentation of high-resolution intravascular ultrasound images

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    AIMS: The aim of this study is to develop and validate a deep learning (DL) methodology capable of automated and accurate segmentation of intravascular ultrasound (IVUS) image sequences in real-time. METHODS AND RESULTS: IVUS segmentation was performed by two experts who manually annotated the external elastic membrane (EEM) and lumen borders in the end-diastolic frames of 197 IVUS sequences portraying the native coronary arteries of 65 patients. The IVUS sequences of 177 randomly-selected vessels were used to train and optimise a novel DL model for the segmentation of IVUS images. Validation of the developed methodology was performed in 20 vessels using the estimations of two expert analysts as the reference standard. The mean difference for the EEM, lumen and plaque area between the DL-methodology and the analysts was ≤0.23mm2 (standard deviation ≤0.85mm2), while the Hausdorff and mean distance differences for the EEM and lumen borders was ≤0.19 mm (standard deviation≤0.17 mm). The agreement between DL and experts was similar to experts' agreement (Williams Index ranges: 0.754-1.061) with similar results in frames portraying calcific plaques or side branches. CONCLUSIONS: The developed DL-methodology appears accurate and capable of segmenting high-resolution real-world IVUS datasets. These features are expected to facilitate its broad adoption and enhance the applications of IVUS in clinical practice and research

    Alignment of retention time obtained from multicapillary column gas chromatography used for VOC analysis with ion mobility spectrometry

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    Multicapillary column (MCC) ion mobility spectrometers (IMS) are increasingly in demand for medical diagnosis, biological applications and process control. In a MCC-IMS, volatile compounds are differentiated by specific retention time and ion mobility when rapid preseparation techniques are applied, e.g. for the analysis of complex and humid samples. Therefore, high accuracy in the determination of both parameters is required for reliable identification of the signals. The retention time in the MCC is the subject of the present investigation because, for such columns, small deviations in temperature and flow velocity may cause significant changes in retention time. Therefore, a universal correction procedure would be a helpful tool to increase the accuracy of the data obtained from a gas-chromatographic preseparation. Although the effect of the carrier gas flow velocity and temperature on retention time is not linear, it could be demonstrated that a linear alignment can compensate for the changes in retention time due to common minor deviations of both the carrier gas flow velocity and the column temperature around the MCC-IMS standard operation conditions. Therefore, an effective linear alignment procedure for the correction of those deviations has been developed from the analyses of defined gas mixtures under various experimental conditions. This procedure was then applied to data sets generated from real breath analyses obtained in clinical studies using different instruments at different measuring sites for validation. The variation in the retention time of known signals, especially for compounds with higher retention times, was significantly improved. The alignment of the retention time—an indispensable procedure to achieve a more precise identification of analytes—using the proposed method reduces the random error caused by small accidental deviations in column temperature and flow velocity significantly

    Quantitative Flow Ratio to Predict Nontarget Vessel-Related Events at 5 Years in Patients With ST-Segment-Elevation Myocardial Infarction Undergoing Angiography-Guided Revascularization.

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    Background In ST-segment-elevation myocardial infarction, angiography-based complete revascularization is superior to culprit-lesion-only percutaneous coronary intervention. Quantitative flow ratio (QFR) is a novel, noninvasive, vasodilator-free method used to assess the hemodynamic significance of coronary stenoses. We aimed to investigate the incremental value of QFR over angiography in nonculprit lesions in patients with ST-segment-elevation myocardial infarction undergoing angiography-guided complete revascularization. Methods and Results This was a retrospective post hoc QFR analysis of untreated nontarget vessels (any degree of diameter stenosis [DS]) from the randomized multicenter COMFORTABLE AMI (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal Stents in Acute ST-Elevation Myocardial Infarction) trial by assessors blinded for clinical outcomes. The primary end point was cardiac death, spontaneous nontarget vessel myocardial infarction, and clinically indicated nontarget vessel revascularization (ie, ≥70% DS by 2-dimensional quantitative coronary angiography or ≥50% DS and ischemia) at 5 years. Of 1161 patients with ST-segment-elevation myocardial infarction, 946 vessels in 617 patients were analyzable by QFR. At 5 years, the rate of the primary end point was significantly higher in patients with QFR ≤0.80 (n=35 patients, n=36 vessels) versus QFR >0.80 (n=582 patients, n=910 vessels) (62.9% versus 12.5%, respectively; hazard ratio [HR], 7.33 [95% CI, 4.54-11.83], P30% DS by 3-dimensional quantitative coronary angiography. Conclusions Our study suggests incremental value of QFR over angiography-guided percutaneous coronary intervention for nonculprit lesions among patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention

    Wall shear stress estimated by 3D-QCA can predict cardiovascular events in lesions with borderline negative fractional flow reserve

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    Background and aims: There is some evidence of the implications of wall shear stress (WSS) derived from three-dimensional quantitative coronary angiography (3D-QCA) models in predicting adverse cardiovascular events. This study investigates the efficacy of 3D-QCA-derived WSS in detecting lesions with a borderline negative fractional flow reserve (FFR: 0.81–0.85) that progressed and caused events. Methods: In this retrospective cohort study, we identified 548 patients who had at least one lesion with an FFR 0.81–0.85 and complete follow-up data; 293 lesions (286 patients) with suitable angiographic characteristics were reconstructed using a dedicated 3D-QCA software and included in the analysis. In the reconstructed models blood flow simulation was performed and the value of 3D-QCA variables and WSS distribution in predicting events was examined. The primary endpoint of the study was the composite of cardiac death, target lesion related myocardial infarction or clinically indicated target lesion revascularization. Results: During a median follow-up of 49.4 months, 37 events were reported. Culprit lesions had a greater area stenosis [(AS), 66.1% (59.5–72.3) vs 54.8% (46.5–63.2), p<0.001], smaller minimum lumen area [(MLA), 1.66 mm2 (1.45–2.30) vs 2.10 mm2 (1.69–2.70), p=0.011] and higher maximum WSS [9.0 Pa (5.10–12.46) vs 5.0 Pa (3.37–7.54), p < 0.001] than those that remained quiescent. In multivariable analysis, AS [hazard ratio (HR): 1.06, 95% confidence interval (CI): 1.03–1.10, p=0.001] and maximum WSS (HR: 1.08, 95% CI: 1.02–1.14, p=0.012) were the only independent predictors of the primary endpoint. Lesions with an increased AS (≥58.6%) that were exposed to high WSS (≥7.69Pa) were more likely to progress and cause events (27.8%) than those with a low AS exposed to high WSS (7.4%) or those exposed to low WSS that had increased (12.8%) or low AS (2.7%, p<0.001). Conclusions: This study for the first time highlights the potential value of 3D-QCA-derived WSS in detecting, among lesions with a borderline negative FFR, those that cause cardiovascular events
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