56 research outputs found
Concert recording 2018-03-02
[Track 1]. Quartet in A major, TWV 43:A1. Soave ; Allegro ; Andante ; Vivace / Georg Phillip Telemann -- [Track 2]. Du bist verflucht, o Shreckensstimmel, TWV 1:385. Aria: Du bist verflucht o Shreckensstimme ; Recitative: So ist\u27s: Seitdem bei Edens Baum des Baum des ersten Menschen erste Sunde ; Aria: Frohlocket, ihr seligen Kinder der Freien! / Telemann -- [Track 3]. Seele, lernce dich erkennen, TWV 1:1258. Aria: Seele, lerne dich erkennen! ; Recitative: Ein Vogelchen, dem noch die Glieder ; Aria: So will ich dich mit Freuden kussen / Telemann -- [Track 4]. Sonatae unarum fidium: Sonata no. 4 in D major. Ciaccona ; Variatio ; Sarabande ; Gigue ; Adagio e recitativo ; Allegro / Johann Heinrich Schmelzer -- [Track 5]. Auf ehernen Mauern, TWV 1:96. Aria; Auf ehernen Mauern, auf marmornen Grunden ; Recitative: So lange noch der Unbestand den Schuchternen ; Aria: Ja, ja, wiederholt nur eure Tucke? / Telemann -- [Track 6]. Nouveaux Quatuors: Quartet no. 6 in E minor, TWV 43:34. Prelude; tres vite ; Gay ; Vite ; Gracieusement ; Distrait ; Modere / Telemann
Phase transition of compartmentalized surface models
Two types of surface models have been investigated by Monte Carlo simulations
on triangulated spheres with compartmentalized domains. Both models are found
to undergo a first-order collapsing transition and a first-order surface
fluctuation transition. The first model is a fluid surface one. The vertices
can freely diffuse only inside the compartments, and they are prohibited from
the free diffusion over the surface due to the domain boundaries. The second is
a skeleton model. The surface shape of the skeleton model is maintained only by
the domain boundaries, which are linear chains with rigid junctions. Therefore,
we can conclude that the first-order transitions occur independent of whether
the shape of surface is mechanically maintained by the skeleton (= the domain
boundary) or by the surface itself.Comment: 10 pages with 16 figure
Fluctuation spectrum of fluid membranes coupled to an elastic meshwork: jump of the effective surface tension at the mesh size
We identify a class of composite membranes: fluid bilayers coupled to an
elastic meshwork, that are such that the meshwork's energy is a function
\textit{not} of the real microscopic membrane area ,
but of a \textit{smoothed} membrane's area , which corresponds to the
area of the membrane coarse-grained at the mesh size . We show that the
meshwork modifies the membrane tension both below and above the scale
, inducing a tension-jump . The
predictions of our model account for the fluctuation spectrum of red blood
cells membranes coupled to their cytoskeleton. Our results indicate that the
cytoskeleton might be under extensional stress, which would provide a means to
regulate available membrane area. We also predict an observable tension jump
for membranes decorated with polymer "brushes"
Phase transition of triangulated spherical surfaces with elastic skeletons
A first-order transition is numerically found in a spherical surface model
with skeletons, which are linked to each other at junctions. The shape of the
triangulated surfaces is maintained by skeletons, which have a one-dimensional
bending elasticity characterized by the bending rigidity , and the surfaces
have no two-dimensional bending elasticity except at the junctions. The
surfaces swell and become spherical at large and collapse and crumple at
small . These two phases are separated from each other by the first-order
transition. Although both of the surfaces and the skeleton are allowed to
self-intersect and, hence, phantom, our results indicate a possible phase
transition in biological or artificial membranes whose shape is maintained by
cytoskeletons.Comment: 15 pages with 10 figure
Phase transition of meshwork models for spherical membranes
We have studied two types of meshwork models by using the canonical Monte
Carlo simulation technique. The first meshwork model has elastic junctions,
which are composed of vertices, bonds, and triangles, while the second model
has rigid junctions, which are hexagonal (or pentagonal) rigid plates.
Two-dimensional elasticity is assumed only at the elastic junctions in the
first model, and no two-dimensional bending elasticity is assumed in the second
model. Both of the meshworks are of spherical topology. We find that both
models undergo a first-order collapsing transition between the smooth spherical
phase and the collapsed phase. The Hausdorff dimension of the smooth phase is
H\simeq 2 in both models as expected. It is also found that H\simeq 2 in the
collapsed phase of the second model, and that H is relatively larger than 2 in
the collapsed phase of the first model, but it remains in the physical bound,
i.e., H<3. Moreover, the first model undergoes a discontinuous surface
fluctuation transition at the same transition point as that of the collapsing
transition, while the second model undergoes a continuous transition of surface
fluctuation. This indicates that the phase structure of the meshwork model is
weakly dependent on the elasticity at the junctions.Comment: 21 pages, 12 figure
Association between Serum Cystatin C and Diabetic Foot Ulceration in Patients with Type 2 Diabetes: A Cross-Sectional Study
Serum cystatin C (CysC) has been identified as a possible potential biomarker in a variety of diabetic complications, including diabetic peripheral neuropathy and peripheral artery disease. We aimed to examine the association between CysC and diabetic foot ulceration (DFU) in patients with type 2 diabetes (T2D). 411 patients with T2D were enrolled in this cross-sectional study at a university hospital. Clinical manifestations and biochemical parameters were compared between DFU group and non-DFU group. The association between serum CysC and DFU was explored by binary logistic regression analysis. The cut point of CysC for DFU was also evaluated by receiver operating characteristic (ROC) curve. The prevalence of coronary artery disease, diabetic nephropathy (DN), and DFU dramatically increased with CysC (P<0.01) in CysC quartiles. Multivariate logistic regression analysis indicated that the significant risk factors for DFU were serum CysC, coronary artery disease, hypertension, insulin use, the differences between supine and sitting TcPO2, and hypertension. ROC curve analysis revealed that the cut point of CysC for DFU was 0.735 mg/L. Serum CysC levels correlated with DFU and severity of tissue loss. Our study results indicated that serum CysC was associated with a high prevalence of DFU in Chinese T2D subjects
Combined Simulation and Experimental Study of Large Deformation of Red Blood Cells in Microfluidic Systems
Author manuscript; available in PMC 2012 March 1.We investigate the biophysical characteristics of healthy human red blood cells (RBCs) traversing microfluidic channels with cross-sectional areas as small as 2.7 × 3 μm. We combine single RBC optical tweezers and flow experiments with corresponding simulations based on dissipative particle dynamics (DPD), and upon validation of the DPD model, predictive simulations and companion experiments are performed in order to quantify cell deformation and pressure–velocity relationships for different channel sizes and physiologically relevant temperatures. We discuss conditions associated with the shape transitions of RBCs along with the relative effects of membrane and cytosol viscosity, plasma environments, and geometry on flow through microfluidic systems at physiological temperatures. In particular, we identify a cross-sectional area threshold below which the RBC membrane properties begin to dominate its flow behavior at room temperature; at physiological temperatures this effect is less profound.Singapore-MIT Alliance for Research and TechnologyUnited States. National Institutes of Health (National Heart, Lung, and Blood Institute Award R01HL094270
CXCR4 identifies transitional bone marrow premonocytes that replenish the mature monocyte pool for peripheral responses
It is well established that Ly6C(hi) monocytes develop from common monocyte progenitors (cMoPs) and reside in the bone marrow (BM) until they are mobilized into the circulation. In our study, we found that BM Ly6C(hi) monocytes are not a homogenous population, as current data would suggest. Using computational analysis approaches to interpret multidimensional datasets, we demonstrate that BM Ly6C(hi) monocytes consist of two distinct subpopulations (CXCR4(hi) and CXCR4(lo) subpopulations) in both mice and humans. Transcriptome studies and in vivo assays revealed functional differences between the two subpopulations. Notably, the CXCR4(hi) subset proliferates and is immobilized in the BM for the replenishment of functionally mature CXCR4(lo) monocytes. We propose that the CXCR4(hi) subset represents a transitional premonocyte population, and that this sequential step of maturation from cMoPs serves to maintain a stable pool of BM monocytes. Additionally, reduced CXCR4 expression on monocytes, upon their exit into the circulation, does not reflect its diminished role in monocyte biology. Specifically, CXCR4 regulates monocyte peripheral cellular activities by governing their circadian oscillations and pulmonary margination, which contributes toward lung injury and sepsis mortality. Together, our study demonstrates the multifaceted role of CXCR4 in defining BM monocyte heterogeneity and in regulating their function in peripheral tissues
Simulations of the Erythrocyte Cytoskeleton at Large Deformation. II. Micropipette Aspiration
Coarse-grained molecular models of the erythrocyte membrane's spectrin cytoskeleton are presented in Monte Carlo simulations of whole cells in micropipette aspiration. The nonlinear chain elasticity and sterics revealed in more microscopic cytoskeleton models (developed in a companion paper; Boey et al., 1998. Biophys. J. 75:1573--1583) are faithfully represented here by two- and three-body effective potentials. The number of degrees of freedom of the system are thereby reduced to a range that is computationally tractable. Three effective models for the triangulated cytoskeleton are developed: two models in which the cytoskeleton is stress-free and does or does not have internal attractive interactions, and a third model in which the cytoskeleton is prestressed in situ. These are employed in direct, finite-temperature simulations of erythrocyte deformation in a micropipette. All three models show reasonable agreement with aspiration measurements made on flaccid human erythrocytes, but ..
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