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Phagosomal Copper-Promoted Oxidative Attack on Intracellular Mycobacterium tuberculosis
No full textCopper (Cu) ions are critical in controlling bacterial infections, and successful pathogens like Mycobacterium tuberculosis (Mtb) possess multiple Cu resistance mechanisms. We report, as proof of concept, that a novel Cu hypersensitivity phenotype can be generated in mycobacteria, including Mtb, through a peptide, DAB-10, that is able to form reactive oxygen species (ROS) following Cu-binding. DAB-10 induces intramycobacterial oxidative stress in a Cu-dependent manner in vitro and during infection. DAB-10 penetrates murine macrophages and encounters intracellular mycobacteria. Significant intracellular Cu-dependent protection was observed when Mtb-infected macrophages were treated with DAB-10 alongside a cell-permeable Cu chelator. Treatment with the Cu chelator reversed the intramycobacterial oxidative shift induced by DAB-10. We conclude that DAB-10 utilizes the pool of phagosomal Cu ions in the host-Mtb interface to augment the mycobactericidal activity of macrophages while simultaneously exploiting the susceptibility of Mtb to ROS. DAB-10 serves as a model with which to develop next-generation, multifunctional antimicrobials
The origin of low bandgap and ferroelectricity of a co-doped BaTiO3
No full textWe recently demonstrated the lowest bandgap bulk ferroelectric, BaTi1-x(Mn1/2Nb1/2)(x)O-3, a promising candidate material for visible light absorption in optoelectronic devices. Using a combination of x-ray spectroscopies and density functional theory (DFT) calculations, we here elucidate this compound's electronic structure and the modifications induced by Mn doping. In particular, we are able to rationalize how this compound retains its ferroelectricity even through a significant reduction of the optical gap upon Mn doping. The local electronic structure and atomic coordination are investigated using x-ray absorption at the Ti K, Mn K, and O K edges, which suggests only small distortions to the parent tetragonal ferroelectric system, BaTiO3, thereby providing a clue to the substantial retention of ferroelectricity in spite of doping. Features at the Ti K edge, which are sensitive to local symmetry and an indication of Ti off-centering within the Ti-O-6 octahedra, show modest changes with doping and strongly corroborates our measured polarization values. Resonant photoelectron spectroscopy results suggest the origin of the reduction of the bandgap in terms of newly created Mn d bands that hybridize with O 2p states. X-ray absorption spectra at the O K edge provide evidence for new states below the conduction band of the parent compound, illustrating additional contributions facilitating bandgap reduction. Copyright (C) EPLA, 201
Remarkable similarity of force induced dsRNA conformational changes to stretched dsDNA and their detection using electrical measurements
No full textIn spite of the striking difference between twist-stretch coupling of dsRNA and dsDNA under external force, dsRNA shows similar structural polymorphism to dsDNA under different pulling protocols. Our atomistic MD simulations show that overstretching dsRNA along the 3 direction of the opposite strands (OS3) leads to the emergence of S-RNA whereas overstretching along the 5 directions of the opposite strands (OS5) leads to melting of dsRNA at lower forces. Using the dsRNA morphology from pulling MD simulations, we use a multiscale method involving ab initio calculations and Kinetic Monte Carlo (KMC) simulations to estimate the conductance of dsRNA and find that the conformational changes drastically affect its conductance. The current through dsRNA chains drastically drops after a critical stretching length and critically depends on the pulling protocol. The critical stretching length for the OS3 pulling case is around 65% higher than that of the OS5 case
Circuit complexity in fermionic field theory
No full textWe define and calculate versions of complexity for free fermionic quantum field theories in 1 + 1 and 3 + 1 dimensions, adopting Nielsen's geodesic perspective in the space of circuits. We do this both by discretizing and identifying appropriate classes of Bogoliubov-Valatin transformations, and also directly in the continuum by defining squeezing operators and their generalizations. As a closely related problem, we consider cMERA tensor networks for fermions: viewing them as paths in circuit space, we compute their path lengths. Certain ambiguities that arise in some of these results because of cutoff dependence are discussed
Origins and diagnostics of the nonequilibrium character of active systems
No full textWe present in detail a Langevin formalism for constructing stochastic dynamical equations for active-matter systems coupled to a thermal bath. We apply the formalism to clarify issues of principle regarding the sources and signatures of nonequilibrium behaviour in a variety of polar and apolar single-particle systems and polar flocks. We show that distance from thermal equilibrium depends on how time-reversal is implemented and hence on the reference equilibrium state. We predict characteristic forms for the frequency-resolved entropy production for an active polar particle in a harmonic potential, which should be testable in experiments
Infrared Spectral Assignment of Pyrimidine and Pyrazine in the C-H Stretching Region by an Effective Spectroscopic Hamiltonian
No full textMid-Infrared spectra of pyrimidine (PM) and pyrazine (PZ) were recorded in the gas phase using a multi-pass long path gas cell. The IR band structure of these compounds above and below 3000 cm(-1) is very broad and contains many humps and shoulders. These humps and shoulders are due to various higher quantum excitation of low-frequency vibrational modes, which participate in Fermi resonance with the nearby C-H stretch fundamentals and appears in this region. We constructed an Effective Spectroscopic Hamiltonian (ESH) in a mixed local mode (LM) normal mode (NM) basis to assign the various overtone and combination bands in the C-H stretching region of these compounds. The C-H stretching vibrations of both PZ and PM were treated as symmetrized anharmonic Morse oscillators in local coordinates and the in-plane deformations down to 1000 cm(-1) were treated as normal coordinates. The ESHs were diagonalized and the resulting eigenvalues were subsequently fitted in a given parameter space with the experimentally observed bands. The eigenvalues of the converged Hamiltonian are the anharmonic frequencies and the transition intensities were obtained by summing the squared eigenvector components. The overtone and combination transitions near 3000 cm(-1) of both PM and PZ were identified and assigned from the eigenvector coefficients of the ESH matrix. The wavefunctions of a pure C-H stretch, overtone of the H-C-C in-plane bend and due to Type 1 Fermi coupling (resonance between a fundamental with an overtones of a low frequency mode, in this case resonance between the C-H strech and the overtone of H-C-C in-plane bending modes) has been demonstrated pictorially
Why Do Males Use Multiple Signals? Insights From Measuring Wild Male Behavior Over Lifespans
No full textWhy animals commonly use multiple conspicuous and presumably costly signals is poorly understood. Tests of evolutionary hypotheses comprehensively covering the signaling repertoire in wild populations are crucial to establish biological relevance, yet are relatively rare. We tested a key hypothesis for the maintenance of multiple signals in a wild population of the lizard, Psammophilus dorsalis, specifically whether multiple signals are maintained as multiple messages directed at different receivers. In addition, we also examined patterns in covariation of signals as an initial test of an alternative hypothesis, that multiple signals may be maintained as redundant signals; such traits are proposed to convey and reinforce the same component of information and are expected to be strongly correlated. Breeding male P. dorsalis display from prominent rock perches within their territories, which overlap multiple female home ranges in rocky open habitats. We repeatedly measured the display behavior, covering the entire signaling repertoire, of individually-tagged wild males on their territories over their lifespans. We quantified patterns of covariation in multiple traits and their relationship with multiple receiver contexts, specifically competitors, mates and predators. We also examined the association between male signaling and indices of lifetime fitness. Males commonly used multiple signals, including behavioral signals and a rare dynamic color signal. These traits were strongly correlated and seemed largely directed toward females, suggesting that they were primarily maintained as redundant signals through female choice. However, other selection pressures also appeared to be important. One color trait seemed to be directed at competitors, providing limited support to the multiple receiver hypothesis. Several traits were reduced in the presence of predators, suggesting that they carry the cost of increased predation risk. Thus, multiple selection pressures, primarily female choice and predation risk, appear to affect male signaling. Finally, signaling traits appeared to influence a measure of lifetime reproductive success, providing rare evidence for the biological relevance of signaling traits under natural contexts
THE MICROSTRUCTURAL ORIGIN OF SINUOUS FLOW IN METAL CUTTING
No full textIn situ, high-speed imaging experiments have revealed the existence of sinuous flow, a recently discovered mode of chip formation in machining. The origin and consequences of sinuous flow are still being investigated, but it is now known that sinuous flow involves extensive redundant plastic deformation, poor surface finish and paradoxically high cutting forces. Here, we use full-scale simulations to show that microstructure related inhomogeneity is a major cause of sinuous flow. The simulations are conducted in a Lagrangian FE framework, and use a simple pseudograin model to represent the metal workpiece as a polycrystalline aggregate. The model successfully captures all essential features of sinuous flow in metals like OFHC copper and CP aluminum, and points to the importance of including material microstructure in cutting simulations
Skin Effect Suppressed Ni-Fe/Cu Electroplated Multilayer Wiring for High Data-Rate and Low Delay-Time I/O Interface Board
No full textApplication of negative permeability beyond ferromagnetic resonance frequency is discussed in this paper. Targeted application is the skin effect suppression technology for long wiring on high-speed and low-delay I/O board. An 11.9 mu m-thick Ni-Fe/Cu multilayer consisting of 0.25 mu m-thick Ni-Fe and 0.51 mu m-thick Cu in turn was electroplated, patterned into 609 mu m-wide and 40 mm-long signal line of microstrip line (MSL) on a 250 mu m-thick printed circuit board. Targeted frequency was 15 GHz, where relative real part permeability was supposed to be -2. The 40 mm-long Ni-Fe/Cu multilayer exhibited the insertion as small as 0.7 dB up to 25 GHz, which is almost the same as the copper monolayer MSL of the same geometry