Invariance of Structure in an Aging Colloidal Glass

We study concentrated colloidal suspensions, a model system which has a glass transition. The non-equilibrium nature of the glassy state is most clearly highlighted by aging -- the dependence of the system's properties on the time elapsed since vitrification. Fast laser scanning confocal microscopy allows us to image a colloidal glass and track the particles in three dimensions. We analyze the static structure in terms of tetrahedral packing. We find that while the aging of the suspension clearly affects its dynamics, none of the geometrical quantities associated with tetrahedra change with age.Comment: Submitted to the proceedings of "The 3rd International Workshop on Complex Systems" in Sendai, Japa

Simulations of aging and plastic deformation in polymer glasses

We study the effect of physical aging on the mechanical properties of a model polymer glass using molecular dynamics simulations. The creep compliance is determined simultaneously with the structural relaxation under a constant uniaxial load below yield at constant temperature. The model successfully captures universal features found experimentally in polymer glasses, including signatures of mechanical rejuvenation. We analyze microscopic relaxation timescales and show that they exhibit the same aging characteristics as the macroscopic creep compliance. In addition, our model indicates that the entire distribution of relaxation times scales identically with age. Despite large changes in mobility, we observe comparatively little structural change except for a weak logarithmic increase in the degree of short-range order that may be correlated to an observed decrease in aging with increasing load.Comment: 9 pages, 12 figure

Visualization of Coherent Destruction of Tunneling in an Optical Double Well System

We report on a direct visualization of coherent destruction of tunneling (CDT) of light waves in a double well system which provides an optical analog of quantum CDT as originally proposed by Grossmann, Dittrich, Jung, and Hanggi [Phys. Rev. Lett. {\bf 67}, 516 (1991)]. The driven double well, realized by two periodically-curved waveguides in an Er:Yb-doped glass, is designed so that spatial light propagation exactly mimics the coherent space-time dynamics of matter waves in a driven double-well potential governed by the Schr\"{o}dinger equation. The fluorescence of Er ions is exploited to image the spatial evolution of light in the two wells, clearly demonstrating suppression of light tunneling for special ratios between frequency and amplitude of the driving field.Comment: final versio

Pharmacological effects of raas blockade in ischemic nephropathy

Background: The management of ischemic nephropathy due to atherosclerotic renal artery stenosis has become increasingly conservative in the modern era, with current guidelines recommending optimized medical therapy as the initial step. The doubts raised by the recently published trials of revascularization strategies have led to a renewed focus on pharmacological strategies promoting blood pressure control and renal protection. It is essential to further elucidate the pathophysiological mechanisms underlying hypoperfusion induced renal microvascular dysfunction with subsequent tissue injury and fibrogenesis. The role of renin angiotensin aldosterone system as a mediator of the main pathophysiological consequences of ischemic nephropathy is well known. However, more recent experimental evidence on the adrenergic system and intrarenal tubular feedback mechanisms has stimulated new interest towards a multi-target therapeutic approach. Methods: This review focuses on the pharmacology of the principle therapeutic drug classes currently used in the treatment of atherosclerotic renal artery stenosis with an analysis of their metabolic aspects and use in clinical practice based on evidence from clinical trials. Results and Conclusions: An optimal pharmacologic approach is crucial for a successful prevention of renal injury and cardiovascular events in this high-risk population. Antihypertensive treatment should include renin angiotensin aldosterone system blockade medication not only for their antihypertensive properties, but especially for those cardio and renoprotectiv

Correlations of Structure and Dynamics in an Aging Colloidal Glass

We study concentrated colloidal suspensions, a model system which has a glass transition. Samples in the glassy state show aging, in that the motion of the colloidal particles slows as the sample ages from an initial state. We study the relationship between the static structure and the slowing dynamics, using confocal microscopy to follow the three-dimensional motion of the particles. The structure is quantified by considering tetrahedra formed by quadruplets of neighboring particles. We find that while the sample clearly slows down during aging, the static properties as measured by tetrahedral quantities do not vary. However, a weak correlation between tetrahedron shape and mobility is observed, suggesting that the structure facilitates the motion responsible for the sample aging.Comment: Submitted to Solid State Communication

Statin pretreatment is protective despite an association with greater coronary artery disease burden in patients presenting with a first ST-elevation myocardial infarction.

The relationship of chronic pre-event statin use with coronary disease severity at the time of presentation with a first acute ST-elevation myocardial infarction (STEMI) is unknown. A retrospective review was performed of consecutive patients presenting with STEMI and without a prior history of vascular disease, divided into those whom had been treated with statins before presentation (n=50) and those whom were not pretreated (n=231). Patients pretreated with statins were more likely to have left main (24.0% vs 8.3%; P=.001) or 3-vessel disease (44.0% vs 25.1%; P=.007) vs untreated patients. After matching for risk factors, a trend toward higher likelihood of 3-vessel disease persisted in the statin pretreatment group (47.6% vs 28.6%; P=.07). Significantly lower peak troponin-I levels (87.8 mg/dL vs 134.5 mg/dL; P=.006) were found in patients pretreated with statins, suggesting that statin pretreatment is protective in patients with STEMI despite the presence of greater disease burden. This finding supports the concept that statin therapy alters the natural history of coronary artery disease development leading to a first STEMI and is cardioprotective in those patients who experience a first STEMI

Evaluation of DyScO(x) as an alternative blocking dielectric in TANOS memories with Si(3)N(4) or Si-rich SiN charge trapping layers

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Stabilization of tetragonal/cubic phase in Fe doped Zirconia grown by atomic layer deposition

Achieving high temperature ferromagnetism by doping transition metals thin films is seen as a viable approach to integrate spin-based elements in innovative spintronic devices. In this work we investigated the effect of Fe doping on structural properties of ZrO2 grown by atomic layer deposition (ALD) using Zr(TMHD)4 for Zr and Fe(TMHD)3 for Fe precursors and ozone as oxygen source. The temperature during the growth process was fixed at 350{\deg}C. The ALD process was tuned to obtain Fe doped ZrO2 films with uniform chemical composition, as seen by time of flight secondary ion mass spectrometry. The control of Fe content was effectively reached, by controlling the ALD precursor pulse ratio, as checked by X-ray photoemission spectroscopy (XPS) and spectroscopic ellipsometry. From XPS, Fe was found in Fe3+ chemical state, which maximizes the magnetization per atom. We also found, by grazing incidence X-ray diffraction, that the inclusion of Fe impurities in ZrO2 induces amorphization in thin ZrO2 films, while stabilizes the high temperature crystalline tetragonal/cubic phase after rapid thermal annealing at 600{\deg}C.Comment: 11 pages, 7 figures, 1 Tabl