7,712 research outputs found
Anomalous thermopower and Nernst effect in : entropy-current loss in precursor state
The heavy-electron superconductor CeCoIn exhibits a puzzling precursor
state above its superconducting critical temperature at = 2.3 K. The
thermopower and Nernst signal are anomalous. Below 15 K, the entropy current of
the electrons undergoes a steep decrease reaching 0 at .
Concurrently, the off-diagonal thermoelectric current is
enhanced. The delicate sensitivity of the zero-entropy state to field implies
phase coherence over large distances. The prominent anomalies in the
thermoelectric current contrast with the relatively weak effects in the
resistivity and magnetization.Comment: 5 figures, 4 page
Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT
The anti--de Sitter/conformal field theory (AdS/CFT) correspondence is a
powerful tool that promises to provide new insights toward a full understanding
of field theories under extreme conditions, including but not limited to
quark-gluon plasma, Fermi liquid and superconductor. In many such applications,
one typically models the field theory with asymptotically AdS black holes.
These black holes are subjected to stringy effects that might render them
unstable. Ho\v{r}ava-Lifshitz gravity, in which space and time undergo
different transformations, has attracted attentions due to its power-counting
renormalizability. In terms of AdS/CFT correspondence, Ho\v{r}ava-Lifshitz
black holes might be useful to model holographic superconductors with Lifshitz
scaling symmetry. It is thus interesting to study the stringy stability of
Ho\v{r}ava-Lifshitz black holes in the context of AdS/CFT. We find that
uncharged topological black holes in Ho\v{r}ava-Lifshitz theory are
nonperturbatively stable, unlike their counterparts in Einstein gravity, with
the possible exceptions of negatively curved black holes with detailed balance
parameter close to unity. Sufficiently charged flat black holes for
close to unity, and sufficiently charged positively curved black
holes with close to zero, are also unstable. The implication to the
Ho\v{r}ava-Lifshitz holographic superconductor is discussed.Comment: 15 pages, 6 figures. Updated version accepted by Phys. Rev. D, with
corrections to various misprints. References update
Optimisation of Fine Pitch Contactor and Test Board for QFN Package
Fine pitch contactor describes a contactor with smaller air gap between the contact pins. It is used for testing small portable devices. This work presents the optimised way of designing the 0.4 mm pitch contactor and test board for QFN package. The signal integrity of fine pitch test contactor has become a concern due to the small air-gap between the pins that leads to signal crosstalk and impedance mismatch issues. The same challenge had been seen when designing the fine pitch test board because of the requirement to meet 0.4 mm pitch for typical hand-held devices. It restricts the trace routing with typical design rules at the contactor mounting area due to the limited spaces. This would bring to impedance discontinuity and crosstalk effect. Therefore, optimised design rules on the fine pitch contactor and test board are necessary. Full-wave modelling and system level simulation were demonstrated to study the fine pitch design rules. While the full-wave modelling was to construct the contactor and test board components, the system level simulation was intended to study the signal transmission when propagating from one component to another. Overall, designing the fine pitch contactor requires extra study on the signal integrity and layout design. This paper presents a method to study and design the fine pitch contactor design. It reports the test board to achieve minimum losses and distortion test system for functional testing. Our simulation results for finepitch contactor model show that the return loss is less than 12 dB at 4 GHz
Structural and molecular basis of the assembly of the TRPP2/PKD1 complex
Mutations in PKD1 and TRPP2 account for nearly all cases of autosomal dominant polycystic kidney disease (ADPKD). These 2 proteins form a receptor/ion channel complex on the cell surface. Using a combination of biochemistry, crystallography, and a single-molecule method to determine the subunit composition of proteins in the plasma membrane of live cells, we find that this complex contains 3 TRPP2 and 1 PKD1. A newly identified coiled-coil domain in the C terminus of TRPP2 is critical for the formation of this complex. This coiled-coil domain forms a homotrimer, in both solution and crystal structure, and binds to a single coiled-coil domain in the C terminus of PKD1. Mutations that disrupt the TRPP2 coiled-coil domain trimer abolish the assembly of both the full-length TRPP2 trimer and the TRPP2/PKD1 complex and diminish the surface expression of both proteins. These results have significant implications for the assembly, regulation, and function of the TRPP2/PKD1 complex and the pathogenic mechanism of some ADPKD-producing mutations
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