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Digit patterning during limb development as a result of the BMP-receptor interaction
(2012)Scientific ReportsTuring models have been proposed to explain the emergence of digits during limb development. However, so far the molecular components that would give rise to Turing patterns are elusive. We have recently shown that a particular type of receptor-ligand interaction can give rise to Schnakenberg-type Turing patterns, which reproduce patterning during lung and kidney branching morphogenesis. Recent knockout experiments have identified Smad4 ...Journal Article -
Programmed death 1 protects from fatal circulatory failure during systemic virus infection of mice
(2012)Journal of Experimental MedicineThe inhibitory programmed death 1 (PD-1)–programmed death ligand 1 (PD-L1) pathway contributes to the functional down-regulation of T cell responses during persistent systemic and local virus infections. The blockade of PD-1–PD-L1–mediated inhibition is considered as a therapeutic approach to reinvigorate antiviral T cell responses. Yet previous studies reported that PD-L1–deficient mice develop fatal pathology during early systemic ...Journal Article -
A Hydration-Based Biophysical Index for the Onset of Soil Microbial Coexistence
(2012)Scientific ReportsMechanistic exploration of the origins of the unparalleled soil microbial biodiversity represents a vast and uncharted scientific frontier. Quantification of candidate mechanisms that promote and sustain such diversity must be linked with microbial functions and measurable biophysical interactions at appropriate scales. We report a novel microbial coexistence index (CI) that links macroscopic soil hydration conditions with microscale ...Journal Article -
Combined Optimal Sizing and Control for a Hybrid Tracked Vehicle
(2012)EnergiesThe optimal sizing and control of a hybrid tracked vehicle is presented and solved in this paper. A driving schedule obtained from field tests is used to represent typical tracked vehicle operations. Dynamics of the diesel engine-permanent magnetic AC synchronous generator set, the lithium-ion battery pack, and the power split between them are modeled and validated through experiments. Two coupled optimizations, one for the plant parameters, ...Journal Article -
Exciton-assisted optomechanics with suspended carbon nanotubes
(2012)New Journal of PhysicsWe propose a framework for inducing strong optomechanical effects in a suspended carbon nanotube based on deformation potential (DP) exciton–phonon coupling. The excitons are confined using an inhomogeneous axial electric field which generates optically active quantum dots with a level spacing in the milli-electronvolt range and a characteristic size in the 10 nm range. A transverse field induces a tunable parametric coupling between the ...Journal Article -
Mammalian SEPT9 isoforms direct microtubule-dependent arrangements of septin core heteromers
(2012)Molecular Biology of the CellSeptin-family proteins assemble into rod-shaped heteromeric complexes that form higher-order arrangements at the cell cortex, where they serve apparently conserved functions as diffusion barriers and molecular scaffolds. There are 13 confirmed septin paralogues in mammals, which may be ubiquitous or tissue specific. Septin hetero-oligomerization appears homology subgroup directed, which in turn determines the subunit arrangement of six- ...Journal Article -
Membranes, viruses, detergents, and endosomes
(2012)Molecular Biology of the CellThe fluid mosaic model for biological membranes was formulated 40 years ago. Ten years later endosomes were discovered as important prelysosomal organelles. At the outset of my research career, I was fortunate to witness both these turning points in biochemistry and cell biology from close up, and to participate in some of the studies. In this short essay, I will describe how this came about, and also try to provide some background as to ...Journal Article -
How to share underground reservoirs
(2012)Scientific ReportsMany resources, such as oil, gas, or water, are extracted from porous soils and their exploration is often shared among different companies or nations. We show that the effective shares can be obtained by invading the porous medium simultaneously with various fluids. Partitioning a volume in two parts requires one division surface while the simultaneous boundary between three parts consists of lines. We identify and characterize these ...Journal Article -
Quantifying the Behavior of Stock Correlations Under Market Stress
(2012)Scientific ReportsUnderstanding correlations in complex systems is crucial in the face of turbulence, such as the ongoing financial crisis. However, in complex systems, such as financial systems, correlations are not constant but instead vary in time. Here we address the question of quantifying state-dependent correlations in stock markets. Reliable estimates of correlations are absolutely necessary to protect a portfolio. We analyze 72 years of daily ...Journal Article -
Electron flow in split-gated bilayer graphene
(2012)New Journal of PhysicsWe present transport measurements on a bilayer graphene sheet with a homogeneous back gate and a split top gate. The electronic transport data indicate the capability of directing electron flow through bilayer graphene nanostructures purely defined by electrostatic gating. Comparing the transconductance data recorded for different top gate geometries—continuous barrier and split gate—the observed transport features for the split gate can ...Journal Article