1,121 research outputs found
A systematic phenomenological study of the asymmetry in unpolarized semi--inclusive DIS
We study the azimuthal asymmetry in unpolarized semi-inclusive
DIS, taking into account both the perturbative contribution (gluon emission and
splitting) and the non perturbative effects arising from intrinsic transverse
motion and transverse spin of quarks. In particular we explore the possibility
to extract from some information about the Boer--Mulders
function $h_1^{\perp}$, which represents a transverse--polarization asymmetry
of quarks inside an unpolarized hadron. Predictions are presented for the
HERMES, COMPASS and JLab kinematics, where is dominated by the
kinematical higher--twist contribution, and turns to be of order of few
percent. We show that a larger asymmetry in production, compared to
production, would represent a signature of the Boer--Mulders effect.Comment: 14 pages, 12 figure
The uniformly frustrated two-dimensional XY model in the limit of weak frustration
We consider the two-dimensional uniformly frustrated XY model in the limit of
small frustration, which is equivalent to an XY system, for instance a
Josephson junction array, in a weak uniform magnetic field applied along a
direction orthogonal to the lattice. We show that the uniform frustration
(equivalently, the magnetic field) destabilizes the line of fixed points which
characterize the critical behaviour of the XY model for T <= T_{KT}, where
T_{KT} is the Kosterlitz-Thouless transition temperature: the system is
paramagnetic at any temperature for sufficiently small frustration. We predict
the critical behaviour of the correlation length and of gauge-invariant
magnetic susceptibilities as the frustration goes to zero. These predictions
are fully confirmed by the numerical simulations.Comment: 12 page
Structural insights on TRPV5 gating by endogenous modulators.
TRPV5 is a transient receptor potential channel involved in calcium reabsorption. Here we investigate the interaction of two endogenous modulators with TRPV5. Both phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and calmodulin (CaM) have been shown to directly bind to TRPV5 and activate or inactivate the channel, respectively. Using cryo-electron microscopy (cryo-EM), we determined TRPV5 structures in the presence of dioctanoyl PI(4,5)P2 and CaM. The PI(4,5)P2 structure reveals a binding site between the N-linker, S4-S5 linker and S6 helix of TRPV5. These interactions with PI(4,5)P2 induce conformational rearrangements in the lower gate, opening the channel. The CaM structure reveals two TRPV5 C-terminal peptides anchoring a single CaM molecule and that calcium inhibition is mediated through a cation-Ï interaction between Lys116 on the C-lobe of calcium-activated CaM and Trp583 at the intracellular gate of TRPV5. Overall, this investigation provides insight into the endogenous modulation of TRPV5, which has the potential to guide drug discovery
Dense dielectric ceramics with local graded structure from core-shell particles: preparation and properties
The modification of the surface properties of particles by coating with a different material, resulting in the formation of core-shell structures, is a well-known process. However, the consolidation of core-shell particles in bulk ceramics has not been extensively investigated yet, mainly because of the difficulty in controlling interdiffusion and interface reactions. In this study, we have coated BaTiO(3) spherical templates with SrTiO(3) and BaZrO(3) using a precipitation process from inorganic precursors. The size of the particles as well as the overall composition can be tailored over a wide range. Densification of the resulting core-shell particles was accomplished either using conventional sintering or spark plasma sintering. Dense ceramics with a graded composition at the level of the single grains could only be obtained by careful choice of the sintering conditions. The final ceramics show strongly modified dielectric properties in comparison to both the parent compounds and the homogeneous solid solutions. The proposed approach is quite generic and suggests new possibilities for the realization of polycrystalline materials with local graded structure by the controlled sintering of core-shell particles
Slow thermo-optomechanical pulsations in suspended 1D photonic crystal nanocavities
We investigate the nonlinear optical response of suspended 1D photonic
crystal nanocavities fabricated on a silicon nitride chip. Strong
thermo-optical nonlinearities are demonstrated for input powers as low as
and a self-sustained pulsing regime is shown to emerge with
periodicity of several seconds. As the input power and laser wavelength are
varied the temporal patterns change in period, duty cycle and shape. This
dynamics is attributed to the multiple timescale competition between
thermo-optical and thermo-optomechanical effects and closely resembles the
relaxation oscillations states found in mathematical models of neuronal
activity. We introduce a simplified model that reproduces all the experimental
observations and allows us to explain them in terms of the properties of a 1D
critical manifold which governs the slow evolution of the system.Comment: 9 pages, 6 figure
How brain-computer interface technology may improve the diagnosis of the disorders of consciousness: A comparative study
ObjectiveClinical assessment of consciousness relies on behavioural assessments, which have several limitations. Hence, disorder of consciousness (DOC) patients are often misdiagnosed. In this work, we aimed to compare the repetitive assessment of consciousness performed with a clinical behavioural and a Brain-Computer Interface (BCI) approach. Materials and methodsFor 7 weeks, sixteen DOC patients participated in weekly evaluations using both the Coma Recovery Scale-Revised (CRS-R) and a vibrotactile P300 BCI paradigm. To use the BCI, patients had to perform an active mental task that required detecting specific stimuli while ignoring other stimuli. We analysed the reliability and the efficacy in the detection of command following resulting from the two methodologies. ResultsOver repetitive administrations, the BCI paradigm detected command following before the CRS-R in seven patients. Four clinically unresponsive patients consistently showed command following during the BCI assessments. ConclusionBrain-Computer Interface active paradigms might contribute to the evaluation of the level of consciousness, increasing the diagnostic precision of the clinical bedside approach. SignificanceThe integration of different diagnostic methods leads to a better knowledge and care for the DOC
Muscle thixotropy: more than just cross-bridges?
AbstractAlthough Campbell and Lakie in a Comment to the Editor in this issue of Biophysical Journal suggested that exclusive cross-bridge action is behind muscle thixotropy, recent findings and our preliminary observations suggest that additional mechanisms could also be involved
Emerging Indoor Photovoltaic Technologies for Sustainable Internet of Things
Funder: Priority Academic Program Development of Jiangsu Higher Education Institutions; Id: http://dx.doi.org/10.13039/501100012246Funder: 111 Project; Id: http://dx.doi.org/10.13039/501100013314Funder: Joint International Research Laboratory of CarbonâBased Functional Materials and DevicesFunder: European Union; Id: http://dx.doi.org/10.13039/501100000780Abstract: The Internet of Things (IoT) provides everyday objects and environments with âintelligenceâ and data connectivity to improve quality of life and the efficiency of a wide range of human activities. However, the ongoing exponential growth of the IoT device ecosystemâup to tens of billions of units to dateâposes a challenge regarding how to power such devices. This Progress Report discusses how energy harvesting can address this challenge. It then discusses how indoor photovoltaics (IPV) constitutes an attractive energy harvesting solution, given its deployability, reliability, and power density. For IPV to provide an ecoâfriendly route to powering IoT devices, it is crucial that its underlying materials and fabrication processes are lowâtoxicity and not harmful to the environment over the product life cycle. A range of IPV technologiesâboth incumbent and emergingâdeveloped to date is discussed, with an emphasis on their environmental sustainability. Finally, IPV based on emerging leadâfree perovskiteâinspired absorbers are examined, highlighting their status and prospects for lowâcost, durable, and efficient energy harvesting that is not harmful to the end user and environment. By examining emerging avenues for ecoâfriendly IPV, timely insight is provided into promising directions toward IPV that can sustainably power the IoT revolution
Understanding heat driven gelation of anionic cellulose nanofibrils: Combining Saturation Transfer Difference (STD) NMR, Small Angle X-ray Scattering (SAXS) and rheology
A novel mechanism of heat-triggered gelation for oxidised cellulose nanofibrils (OCNF) is reported. We demonstrate that a synergistic approach combining rheology, small-angle X-ray scattering (SAXS) and saturation transfer difference NMR (STD NMR) experiments enables a detailed characterisation of gelation at different length scales. OCNF dispersions experience an increase in solid-like behaviour upon heating as evidenced by rheological studies, associated with enhanced interfibrillar interactions measured using SAXS. Interactions result in an increased fibrillar overlap and increased population of confined water molecules monitored by STD NMR. In comparison, cationic cellulose nanofibrils (produced by reaction of cellulose with trimethylglycidylammonium chloride) were found to be heat-unresponsive
- âŠ