2,515 research outputs found
Graphoidal Tree d - Cover
Acharya and Sampathkumar defined a graphoidal cover as a partition of edges into internally disjoint (not necessarily open) paths. If we consider only open paths in
the above definition then we call it as a graphoidal path cover
Transitions to Nematic states in homogeneous suspensions of high aspect ratio magnetic rods
Isotropic-Nematic and Nematic-Nematic transitions from a homogeneous base
state of a suspension of high aspect ratio, rod-like magnetic particles are
studied for both Maier-Saupe and the Onsager excluded volume potentials. A
combination of classical linear stability and asymptotic analyses provides
insight into possible nematic states emanating from both the isotropic and
nematic non-polarized equilibrium states. Local analytical results close to
critical points in conjunction with global numerical results (Bhandar, 2002)
yields a unified picture of the bifurcation diagram and provides a convenient
base state to study effects of external orienting fields.Comment: 3 Figure
Active elastohydrodynamics of vesicles in narrow, blind constrictions
Fluid-resistance limited transport of vesicles through narrow constrictions
is a recurring theme in many biological and engineering applications. Inspired
by the motor-driven movement of soft membrane-bound vesicles into closed
neuronal dendritic spines, here we study this problem using a combination of
passive three-dimensional simulations and a simplified semi-analytical theory
for active transport of vesicles that are forced through such constrictions by
molecular motors. We show that the motion of these objects is characterized by
two dimensionless quantities related to the geometry and the strength of
forcing relative to the vesicle elasticity. We use numerical simulations to
characterize the transit time for a vesicle forced by fluid pressure through a
constriction in a channel, and find that relative to an open channel, transport
into a blind end leads to the formation of an effective lubrication layer that
strongly impedes motion. When the fluid pressure forcing is complemented by
forces due to molecular motors that are responsible for vesicle trafficking
into dendritic spines, we find that the competition between motor forcing and
fluid drag results in multistable dynamics reminiscent of the real system. Our
study highlights the role of non-local hydrodynamic effects in determining the
kinetics of vesicular transport in constricted geometries
QoS Framework for a Multi-stack based Heterogeneous Wireless Sensor Network
Wireless sensor nodes consist of a collection of sensor nodes with constrained resources in terms of processing power and battery energy. Wireless sensors networks are used increasingly in many industrial and consumer applications. Sensors detect events and send via multi hop routing to the sink node for processing the event. The routing path is established through proactive or reactive routing protocols. To improve the performance of the Wireless Sensor Networks, multi stack architecture is addressed. But the multi stack architecture has many problems with respect to life time, routing loop and QOS. In this work we propose a solution to address all these three problems of life time, routing loop and QOS in case of multi stack architecture
Efficient differentiation of murine embryonic stem cells requires the binding of CXXC finger protein 1 to DNA or methylated histone H3-Lys4
Mammalian CXXC finger protein 1 (Cfp1) is a DNA-binding protein that is a component of the Setd1 histone methyltransferase complexes and is a critical epigenetic regulator of both histone and cytosine methylation. Murine embryonic stem (ES) cells lacking Cfp1 exhibit a loss of histone H3-Lys4 tri-methylation (H3K4me3) at many CpG islands, and a mis-localization of this epigenetic mark to heterochromatic sub-nuclear domains. Furthermore, these cells fail to undergo cellular differentiation in vitro. These defects are rescued upon introduction of a Cfp1-expression vector. Cfp1 contains an N-terminal plant homeodomain (PHD), a motif frequently observed in chromatin associated proteins that functions as a reader module of histone marks. Here, we report that the Cfp1 PHD domain directly and specifically binds to histone H3K4me1/me2/me3 marks. Introduction of individual mutations at key Cfp1 PHD residues (Y28, D44, or W49) ablates this histone interaction both in vitro and in vivo. The W49A point mutation does not affect the ability of Cfp1 to rescue appropriate restriction of histone H3K4me3 to euchromatic sub-nuclear domains or in vitro cellular differentiation in Cfp1-null ES cells. Similarly, a mutated form of Cfp1 that lacks DNA-binding activity (C169A) rescues in vitro cellular differentiation. However, rescue of Cfp1-null ES cells with a double mutant form of Cfp1 (W49A, C169A) results in partially defective in vitro differentiation. These data define the Cfp1 PHD domain as a reader of histone H3K4me marks and provide evidence that this activity is involved in the regulation of lineage commitment in ES cells
First Results from the Transit Ephemeris Refinement and Monitoring Survey (TERMS)
Transiting planet discoveries have yielded a plethora of information towards understanding the structure and atmospheres of extra-solar planets. These discoveries have been restricted to the short-period or low-periastron distance regimes due to the bias inherent in the geometric transit probability. Through the refinement of planetary orbital parmaters, and hence reducing the size of transit windows, long-period planets become feasible targets for photometric follow-up. Here we describe the TERMS project which is monitoring these host stars at predicted transit times
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