Publications by authors named "Harth K"

Background: Nutcracker syndrome (NCS) describes the symptomatic compression of the left renal vein between the aorta and superior mesenteric artery. Whereas asymptomatic compression is a common radiological finding, patients with NCS can report a range of symptoms. There are no specific diagnostic criteria and interventions include a range of open surgical and endovascular procedures.

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In the past decade, technologies to treat venous pathologies have increased dramatically, to the benefit of an often underserved and overlooked population of patients with venous disease. However, given the rapid release of various technologies, including venous-dedicated stents and thrombectomy devices across varied venous pathologies, evidence-based guidelines have been slow to develop. When discussing appropriateness of care, one needs to consider optimal patient selection, technical approach, medical management, and surveillance protocols, to name a few.

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A granular gas composed of monodisperse spherical particles was studied in microgravity experiments in a drop tower. Translations and rotations of the particles were extracted from optical video data. Equipartition is violated, the rotational degrees of freedom were excited only to roughly 2/3 of the translational ones.

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Granular gases are fascinating non-equilibrium systems with interesting features such as spontaneous clustering and non-Gaussian velocity distributions. Mixtures of different components represent a much more natural composition than monodisperse ensembles but attracted comparably little attention so far. We present the observation and characterization of a mixture of rod-like particles with different sizes and masses in a drop tower experiment.

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We investigate micrometer-sized flat droplets consisting of an isotropic core surrounded by a nematic rim in freely suspended smectic A liquid-crystal films. In contrast to purely isotropic droplets which are characterized by a sharp edge and no long-range interactions, the nematic fringe introduces a continuous film thickness change resulting in long-range mutual attraction of droplets. The coalescence scenario is divided in two phases.

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CD8 T cells are emerging as important mediators in atherosclerosis and cardiovascular disease (CVD). Immune activation may play a particular role in people with HIV (PWH) who are at an increased risk of CVD, even after controlling for known CVD risk factors. Latent CMV infection is associated with increased CVD risk for both PWH and people without HIV, and human CMV-specific CD4 and CD8 T cells are enriched for an immunosenescent phenotype.

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The full spectrum of venous disease poses a significant burden on individuals and health-care systems globally. Venous disease can lead to a wide range of symptoms based on the level of disease and underlying pathology. In general, underlying pathologies are due to nonthrombotic (reflux/obstructive) and thrombotic causes.

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Disclinations or disclination clusters in smectic C freely suspended films with topological charges larger than one are unstable. They disintegrate, preferably in a spatially symmetric fashion, into single defects with individual charges of +1, which is the smallest positive topological charge allowed in polar vector fields. While the opposite process of defect annihilation is well-defined by the initial defect positions, disintegration starts from a singular state and the following scenario including the emerging regular defect patterns must be selected by specific mechanisms.

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Objective: Intravascular ultrasound (IVUS) use in lower extremity interventions is growing in popularity owing to its imaging in the axial plane, superior detail in imaging lesion characteristics, and its enhanced ability to delineate lesion severity and extent compared with catheter angiograms. However, there are conflicting data regarding whether IVUS affects outcomes. The purpose of this study was to assess the effect associated with IVUS implementation in femoropopliteal interventions.

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Smectic liquid crystals are fluids, and in most rheological situations they behave as such. Nevertheless, when thin freely floating films of smectic A or smectic C materials are compressed quickly in-plane, they resist such stress by buckling similar to solid membranes under lateral stress. We report experimental observations of wrinkling and bulging of finite domains within the films, so-called islands, and give a qualitative explanation of different observed patterns.

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Objective: Physician-modified endografts (PMEG) and parallel grafting (PG) are important techniques for endovascular repair of complex aortic aneurysms using off-the-shelf devices. However, there are few data regarding the relative efficacy and outcomes of these techniques in thoracoabdominal extent aneurysms. This study sought to compare the outcomes of PG and PMEG across different extents of thoracoabdominal aneurysms (TAAAs) for which they can be used.

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Smectic freely-suspended films can wrinkle like solid sheets. This has been demonstrated earlier with shape-fluctuating smectic bubbles. Here, we exploit the collapse of smectic catenoid films with a central equatorial film to expose the latter to rapid lateral compression.

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Objective: Management of carotid artery stenosis (CAS) remains controversial and proper patient selection critical. Elevated neutrophil to lymphocyte ratio (NLR) has been associated with poor outcomes after vascular procedures. The effect of NLR on outcomes after carotid endarterectomy (CEA) in asymptomatic and symptomatic patients is assessed.

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We describe the collective behavior of isotropic droplets dispersed over a spherical smectic bubble, observed under microgravity conditions on the International Space Station (ISS). We find that droplets can form two-dimensional hexagonal structures changing with time. Our analysis indicates the possibility of spatial and temporal periodicity of such structures of droplets.

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Background: An elevated neutrophil-lymphocyte ratio (NLR) is a biomarker associated with adverse outcomes after cardiovascular surgery. This study evaluates the association of preoperative NLR with clinical outcomes after peripheral vascular intervention (PVI) of the femoropopliteal segments.

Methods: A retrospective review identified 488 patients who underwent percutaneous interventions of femoropopliteal arteries between 2011 and 2018 and had a pre-procedural complete blood count with differential with normal white blood cell count within 30 days prior to intervention.

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Objective: Paclitaxel (PTX)-coated peripheral arterial devices have been shown to decrease femoropopliteal artery restenosis and the need for reintervention compared with non-PTX-coated devices. The data regarding PTX efficacy and safety come from randomized controlled trials that almost exclusively enrolled patients with claudication. The outcomes of PTX treatment in patients who present with chronic limb-threatening ischemia (CLTI) are unknown.

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Granular multiparticle ensembles are of interest from fundamental statistical viewpoints as well as for the understanding of collective processes in industry and in nature. Extraction of physical data from optical observations of three-dimensional (3D) granular ensembles poses considerable problems. Particle-based tracking is possible only at low volume fractions, not in clusters.

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We study the outflow dynamics and clogging phenomena of mixtures of soft, elastic low-friction spherical grains and hard frictional spheres of similar size in a quasi-two-dimensional (2D) silo with narrow orifice at the bottom. Previous work has demonstrated the crucial influence of elasticity and friction on silo discharge. We show that the addition of small amounts, even as low as 5%, of hard grains to an ensemble of soft, low-friction grains already has significant consequences.

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Background: Hemostatic agents are routinely used in vascular surgery to complement proper suture techniques and decrease the risk of perioperative bleeding. A relative lack of comparative research studies have left surgeons with the option of choosing hemostatic agents based on their personal experience. The present review has highlighted the efficacy and safety of hemostatic agents and categorized them according to their primary mechanism of action and cost.

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Atherosclerotic cardiovascular disease (ASCVD) remains an important cause of morbidity in the general population and risk for ASCVD is increased approximately 2-fold in persons living with HIV infection (PLWH). This risk is linked to elevated CD8 T cell counts that are abundant in atherosclerotic plaques and have been implicated in disease pathogenesis yet the mechanisms driving T cell recruitment to and activation within plaques are poorly defined. Here we investigated the role of CD8 T cells in atherosclerosis in a non-human primate model of HIV infection and in the HIV-uninfected elderly; we sought to identify factors that promote the activation, function, and recruitment to endothelium of CX3CR1+ CD8 T cells.

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Background: Paclitaxel-coated devices have been shown to decrease restenosis when used in the femoropopliteal artery. Recent reports have suggested a possible risk of increased late mortality in patients treated with paclitaxel. It has been suggested that younger patients and those with limited comorbidities may be at higher risk.

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Soft, low-friction particles in silos show peculiar features during their discharge. The outflow velocity and the clogging probability both depend upon the momentary silo fill height, in sharp contrast to silos filled with hard particles. The reason is the fill-height dependence of the pressure at the orifice.

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When a liquid drop impacts on a heated substrate, it can remain deposited, or violently boil in contact, or lift off with or without ever touching the surface. The latter is known as the Leidenfrost effect. The duration and area of the liquid-substrate contact are highly relevant for the heat transfer, as well as other effects such as corrosion.

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