A compact design for the Josephson mixer: the lumped element circuit

We present a compact and efficient design in terms of gain, bandwidth and dynamical range for the Josephson mixer, the superconducting circuit performing three-wave mixing at microwave frequencies. In an all lumped-element based circuit with galvanically coupled ports, we demonstrate non degenerate amplification for microwave signals over a bandwidth up to 50 MHz for a power gain of 20 dB. The quantum efficiency of the mixer is shown to be about 70$\%$ and its saturation power reaches $-112$ dBm.Comment: 5 pages, 4 figure

Murine and human myogenic cells identified by elevated aldehyde dehydrogenase activity: Implications for muscle regeneration and repair

Background: Despite the initial promise of myoblast transfer therapy to restore dystrophin in Duchenne muscular dystrophy patients, clinical efficacy has been limited, primarily by poor cell survival post-transplantation. Murine muscle derived stem cells (MDSCs) isolated from slowly adhering cells (SACs) via the preplate technique, induce greater muscle regeneration than murine myoblasts, primarily due to improved post-transplantation survival, which is conferred by their increased stress resistance capacity. Aldehyde dehydrogenase (ALDH) represents a family of enzymes with important morphogenic as well as oxidative damage mitigating roles and has been found to be a marker of stem cells in both normal and malignant tissue. In this study, we hypothesized that elevated ALDH levels could identify murine and human muscle derived cell (hMDC) progenitors, endowed with enhanced stress resistance and muscle regeneration capacity. Methodology/Principal Findings: Skeletal muscle progenitors were isolated from murine and human skeletal muscle by a modified preplate technique and unfractionated enzymatic digestion, respectively. ALDHhisubpopulations isolated by fluorescence activate cell sorting demonstrated increased proliferation and myogenic differentiation capacities compared to their ALDHlocounterparts when cultivated in oxidative and inflammatory stress media conditions. This behavior correlated with increased intracellular levels of reduced glutathione and superoxide dismutase. ALDHhimurine myoblasts were observed to exhibit an increased muscle regenerative potential compared to ALDHlomyoblasts, undergo multipotent differentiation (osteogenic and chondrogenic), and were found predominately in the SAC fraction, characteristics that are also observed in murine MDSCs. Likewise, human ALDHhihMDCs demonstrated superior muscle regenerative capacity compared to ALDHlohMDCs. Conclusions: The methodology of isolating myogenic cells on the basis of elevated ALDH activity yielded cells with increased stress resistance, a behavior that conferred increased regenerative capacity of dystrophic murine skeletal muscle. This result demonstrates the critical role of stress resistance in myogenic cell therapy as well as confirms the role of ALDH as a marker for rapid isolation of murine and human myogenic progenitors for cell therapy. © 2011 Vella et al

Contact resistance and shot noise in graphene transistors

Potential steps naturally develop in graphene near metallic contacts. We investigate the influence of these steps on the transport in graphene Field Effect Transistors. We give simple expressions to estimate the voltage-dependent contribution of the contacts to the total resistance and noise in the diffusive and ballistic regimes.Comment: 6 pages, 4 figures; Figs 3 and 4 completed and appendix adde

On the central quadric ansatz: integrable models and Painleve reductions

It was observed by Tod and later by Dunajski and Tod that the Boyer-Finley (BF) and the dispersionless Kadomtsev-Petviashvili (dKP) equations possess solutions whose level surfaces are central quadrics in the space of independent variables (the so-called central quadric ansatz). It was demonstrated that generic solutions of this type are described by Painleve equations PIII and PII, respectively. The aim of our paper is threefold: -- Based on the method of hydrodynamic reductions, we classify integrable models possessing the central quadric ansatz. This leads to the five canonical forms (including BF and dKP). -- Applying the central quadric ansatz to each of the five canonical forms, we obtain all Painleve equations PI - PVI, with PVI corresponding to the generic case of our classification. -- We argue that solutions coming from the central quadric ansatz constitute a subclass of two-phase solutions provided by the method of hydrodynamic reductions.Comment: 12 page

Mouse adipose-derived stem cells undergo multilineage differentiation in vitro but primarily osteogenic and chondrogenic differentiation in vivo

Human, rat, and mouse studies have demonstrated the existence of a population of adipose-derived adult stem (ADAS) cells that can undergo multilineage differentiation in vitro. However, it remains unclear whether these cells maintain their multilineage potential in vivo. The aim of this study was to examine the in vitro and in vivo characteristics and behavior of a potential population of murine ADAS (muADAS) cells isolated from the visceral fat of the abdominal cavity of C57BL/10J mice. We used flow cytometry to examine the cells' expression of CD29, CD31, CD45, CD34, CD44, CD144, CD146, Flk1, and Sca-1. The isolated cell population was CD45 negative, which precludes contamination by hematopoietic cells, but was partially positive for Sca-1 and CD34: 2 stem-cell markers. After induction in conditioned medium, the muADAS cells gained the ability to undergo adipogenic, osteogenic, chondrogenic, myogenic, and hematopoietic differentiation in vitro. The muADAS cells readily differentiated to form bone and cartilage in vivo for up to 24 weeks, but their ability to regenerate muscle or reconstitute bone marrow was found to be limited. © Mary Ann Liebert, Inc