Models of dynamic extraction of lipid tethers from cell membranes

When a ligand that is bound to an integral membrane receptor is pulled, the membrane and the underlying cytoskeleton can deform before either the membrane delaminates from the cytoskeleton or the ligand detaches from the receptor. If the membrane delaminates from the cytoskeleton, it may be further extruded and form a membrane tether. We develop a phenomenological model for this processes by assuming that deformations obey Hooke's law up to a critical force at which the cell membrane locally detaches from the cytoskeleton and a membrane tether forms. We compute the probability of tether formation and show that they can be extruded only within an intermediate range of force loading rates and pulling velocities. The mean tether length that arises at the moment of ligand detachment is computed as are the force loading rates and pulling velocities that yield the longest tethers.Comment: 16 pages, 7 figure

Influence of antioxidant location on the protection of oil encapsulated in powder

Encapsulation of Poly Unsaturated Fatty Acids (PUFAs) in solid matrix, by providing a physical barrier, is used to prevent or delay their degradation; and the use of antioxidant is expected to enhance PUFAs oxidative stability. In liquid emulsions, the effectiveness of antioxidants is known to depend on their distribution between the oil and aqueous phase. In this study, the impact of the lipophilic or hydrophilic character of phenolic antioxidants on the oxidative stability of encapsulated PUFAs was investigated following the evolution of conjugated dienes and antioxidant residual content during accelerated ageing test (50\ub0C, 60% RH). Dry emulsions containing 10%wt stripped sunflower oil (60% PUFAs), 89.7%wt maltodextrin DE12 (wall material) and 0.3%wt Tween\uae20 (surfactant) were produced by spray drying. Some were enriched with alpha-tocopherol (lipophilic - 500 ppm in oil) or chlorogenic acid (hydrophilic, 1000 ppm in maltodextrin), two scavengers of lipid radicals implied in oxidation.Antioxidants improved the oxidative stability of encapsulated oil. With chlorogenic acid, oil oxidation occurred after a two days lag phase whilst for alpha-tocopherol, no lag phase was observed but the oxidation rate was smaller than in control and chlorogenic acid powders during the ten first days of ageing (Fig, 1a). The residual concentration of chlorogenic acid deceased rapidly during the first two days and then remained constant whilst the concentration of alphatocopherol decreased regularly ensuring oil protection until it has been totally consumed after ten days (Fig.1b). The better oil protection provided by alpha-tocopherol during the first ten days of storage was attributed to the different location of both antioxidants within the macro-domains of the dry emulsion. Alpha-tocopherol, in oil droplets, was directly in contact with the oil to protect whilst for chlorogenic acid, entrapped in the solid matrix, only the fraction in contact with the oil droplets brought protection and 60% of initial chlorogenic acid remained preserved in the matrix

A Lower-bound for Variable-length Source Coding in LQG Feedback Control

In this letter, we consider a Linear Quadratic Gaussian (LQG) control system where feedback occurs over a noiseless binary channel and derive lower bounds on the minimum communication cost (quantified via the channel bitrate) required to attain a given control performance. We assume that at every time step an encoder can convey a packet containing a variable number of bits over the channel to a decoder at the controller. Our system model provides for the possibility that the encoder and decoder have shared randomness, as is the case in systems using dithered quantizers. We define two extremal prefix-free requirements that may be imposed on the message packets; such constraints are useful in that they allow the decoder, and potentially other agents to uniquely identify the end of a transmission in an online fashion. We then derive a lower bound on the rate of prefix-free coding in terms of directed information; in particular we show that a previously known bound still holds in the case with shared randomness. We also provide a generalization of the bound that applies if prefix-free requirements are relaxed. We conclude with a rate-distortion formulation.Comment: Under dual submission to the IEEE Control Systems Letters and the 61st IEEE Conference on Decision and Control. This version fixed typo in the references for the original versio

A Noncoherent Space-Time Code from Quantum Error Correction

In this work, we develop a space-time block code for noncoherent communication using techniques from the field of quantum error correction. We decompose the multiple-input multiple-output (MIMO) channel into operators from quantum mechanics, and design a non-coherent space time code using the quantum stabilizer formalism. We derive an optimal decoder, and analyze the former through a quantum mechanical lens. We compare our approach to a comparable coherent approach and a noncoherent differential approach, achieving comparable or better performance.Comment: 6 pages, one figure, accepted at the 53rd annual Conference on Information Sciences and System

Transplantation for renal failure secondary to enteric hyperoxaluria: a case report

Enteric hyperoxaluria can lead to renal failure. There have only been a few reports of renal transplantation as treatment of endstage renal disease secondary to enteric hyperoxaluria and results have been mixed. This report describes a patient with Crohn's disease who developed chronic renal failure from enteric hyperoxaluria. He subsequently had a successful renal transplant without any post-operative oxalate related complications and has satisfactory renal function almost three years later. Aggressive pre-transplant hemodialysis was not done. The literature associated with renal transplantation for enteric hyperoxaluria is reviewed

A multi-model study of the hemispheric transport and deposition of oxidised nitrogen.

Fifteen chemistry-transport models are used to quantify, for the first time, the export of oxidised nitrogen (NOy) to and from four regions (Europe, North America, South Asia, and East Asia), and to estimate the uncertainty in the results. Between 12 and 24% of the NOx emitted is exported from each region annually. The strongest impact of each source region on a foreign region is: Europe on East Asia, North America on Europe, South Asia on East Asia, and East Asia on North America. Europe exports the most NOy, and East Asia the least. East Asia receives the most NOy from the other regions. Between 8 and 15% of NOx emitted in each region is transported over distances larger than 1000 km, with 3–10% ultimately deposited over the foreign regions