Ultrafast spin-to-charge conversions of antiferromagnetic (111)-oriented L12\mathrm{L1_2}-Mn3Ir\mathrm{Mn_3Ir}

Antiferromagnetic $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$ combines outstanding spin-transport properties with magnons in the terahertz (THz) frequency range. However, the THz radiation emitted by ultrafast spin-to-charge conversion via the inverse spin Hall effect remains unexplored. In this study, we measured the THz emission and transmission of a permalloy/(111)-oriented $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$ multilayer by THz time-domain spectroscopy. The spin Hall angle was determined to be approximately constant at 0.024 within a frequency range of 0.3-2.2 THz, in comparison with the THz spectroscopy of a permalloy/Pt multilayer. Our results not only demonstrate the potential of $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$ as a spintronic THz emitter but also provide insights into the THz spin transport properties of $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$.Comment: 11 pages, 5 figure

Formation of naked singularities in five-dimensional space-time

We numerically investigate the gravitational collapse of collisionless particles in spheroidal configurations both in four and five-dimensional (5D) space-time. We repeat the simulation performed by Shapiro and Teukolsky (1991) that announced an appearance of a naked singularity, and also find that the similar results in 5D version. That is, in a collapse of a highly prolate spindle, the Kretschmann invariant blows up outside the matter and no apparent horizon forms. We also find that the collapses in 5D proceed rapidly than in 4D, and the critical prolateness for appearance of apparent horizon in 5D is loosened compared to 4D cases. We also show how collapses differ with spatial symmetries comparing 5D evolutions in single-axisymmetry, SO(3), and those in double-axisymmetry, U(1)$\times$U(1).Comment: 5 pages, 5 figures, To be published in Phys. Rev.

Activation of cytosolic phospholipase A2 in dorsal root ganglion neurons by Ca2+/calmodulin-dependent protein kinase II after peripheral nerve injury

<p>Abstract</p> <p>Background</p> <p>Peripheral nerve injury leads to a persistent neuropathic pain state in which innocuous stimulation elicits pain behavior (tactile allodynia), but the underlying mechanisms have remained largely unknown. We have previously shown that spinal nerve injury induces the activation of cytosolic phospholipase A₂(cPLA₂) in injured dorsal root ganglion (DRG) neurons that contribute to tactile allodynia. However, little is known about the signaling pathway that activates cPLA₂after nerve injury. In the present study, we sought to determine the mechanisms underlying cPLA₂activation in injured DRG neurons in an animal model of neuropathic pain, focusing on mitogen-activated protein kinases (MAPKs) and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII).</p> <p>Results</p> <p>Pharmacological inhibition of either p38 or extracellular signal-regulated kinase (ERK) in the injured DRG, which led to suppression of the development of tactile allodynia, did not affect cPLA₂phosphorylation and translocation after nerve injury. By contrast, a CaMKII inhibitor prevented the development and expression of nerve injury-induced tactile allodynia and reduced both the level of cPLA₂phosphorylation and the number of DRG neurons showing translocated cPLA₂in response to nerve injury. Applying ATP to cultured DRG neurons increased the level of both phosphorylated cPLA₂and CaMKII in the vicinity of the plasma membrane and caused physical association of these two proteins. In addition, ATP-stimulated cPLA₂and CaMKII phosphorylation were inhibited by both a selective P2X₃R/P2X₂₊₃R antagonist and a nonselective voltage-dependent Ca²⁺channel (VDCC) blocker.</p> <p>Conclusion</p> <p>These results suggest that CaMKII, but not MAPKs, has an important role in cPLA₂activation following peripheral nerve injury, probably through P2X₃R/P2X₂₊₃R and VDCCs in primary afferent neurons.</p

CTX: A Clock-Gating-Based Test Relaxation and X-Filling Scheme for Reducing Yield Loss Risk in At-Speed Scan Testing

At-speed scan testing is susceptible to yield loss risk due to power supply noise caused by excessive launch switching activity. This paper proposes a novel two-stage scheme, namely CTX (Clock-Gating-Based Test Relaxation and X-Filling), for reducing switching activity when test stimulus is launched. Test relaxation and X-filling are conducted (1) to make as many FFs inactive as possible by disabling corresponding clock-control signals of clock-gating circuitry in Stage-1 (Clock-Disabling), and (2) to make as many remaining active FFs as possible to have equal input and output values in Stage-2 (FF-Silencing). CTX effectively reduces launch switching activity, thus yield loss risk, even with a small number of donpsilat care (X) bits as in test compression, without any impact on test data volume, fault coverage, performance, and circuit design.2008 17th Asian Test Symposium (ATS 2008), 24-27 November 2008, Sapporo, Japa

The cross-correlation search for a hot spot of gravitational waves

The cross-correlation search has been previously applied to map the gravitational wave (GW) stochastic background in the sky and also to target GW from rotating neutron stars/pulsars. Here we investigate how the cross-correlation method can be used to target a small region in the sky spanning at most a few pixels, where a pixel in the sky is determined by the diffraction limit which depends on the (i) baseline joining a pair of detectors and (ii) detector bandwidth. Here as one of the promising targets, we consider the Virgo cluster - a "hot spot" spanning few pixels - which could contain, as estimates suggest $\sim 10^{11}$ neutron stars, of which a small fraction would continuously emit GW in the bandwidth of the detectors. For the detector baselines, we consider advanced detector pairs among LCGT, LIGO, Virgo, ET etc. Our results show that sufficient signal to noise can be accumulated with integration times of the order of a year. The results improve for the multibaseline search. This analysis could as well be applied to other likely hot spots in the sky and other possible pairs of detectors.Comment: 7 pages, 2 figure

Transport Between Palau and the Eastern Coral Triangle: Larval Connectivity or Near Misses

Physical connectivity by transport of larvae between different habitats plays a fundamental role in marine population dynamics and is often assessed using circulation models assuming that computed large-scale connectivity describes the actual connectivity. This paper presents observations of drifters released into the Philippine Sea offshore of the western lagoon of Palau that were tracked as were first carried by the Mindanao Eddy toward Mindanao and other parts of the Celebes and Sulu Seas, where they were removed from the water. While following expected transport pathways for this region, our drifters remained at least several kilometers offshore of the various islands they passed by, suggesting that larvae moving similarly would have been too far offshore to recruit to nearshore reefs. Thus, estimates of connectivity made using large-scale models must be taken as upper bounds to connectivity across ocean basins. Plain Language Summary A major consideration in marine conservation is the connectivity between different habitats or regions of the ocean, that is, the degree to which populations in those places are linked to each through the movement of eggs, larvae, eggs, or adults between them. One area of particular interest is the Western Pacific and its connections with the Coral Triangle. In this study, we deployed a set of satellite-tracked surface drifters offshore of the west side of Palau that moved in the local ocean circulation toward and then past Mindanao, in some cases completing multiple circuits around the Philippine Sea. These drifter tracks demonstrate an important aspect of connectivity in the ocean: In the absence of strong and directed swimming, local flow processes on ocean shelves that can act to transport materials toward shore may control the real extent of connectivity across ocean basins. Thus, the degree of connectivity inferred from large-scale flows (either modeled or observed remotely) is an upper bound on the actual degree of connectivity. Importantly, these results demonstrate that marine conservation efforts for coral reefs based on ocean-basin scale connectivity need to include consideration of flow behavior at ocean boundaries where reefs are located

Fractal Reconnection in Solar and Stellar Environments

Recent space based observations of the Sun revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Often the magnetic reconnection events are associated with mass ejections or jets, which seem to be closely related to multiple plasmoid ejections from fractal current sheet. The bursty radio and hard X-ray emissions from flares also suggest the fractal reconnection and associated particle acceleration. We shall discuss recent observations and theories related to the plasmoid-induced-reconnection and the fractal reconnection in solar flares, and their implication to reconnection physics and particle acceleration. Recent findings of many superflares on solar type stars that has extended the applicability of the fractal reconnection model of solar flares to much a wider parameter space suitable for stellar flares are also discussed.Comment: Invited chapter to appear in "Magnetic Reconnection: Concepts and Applications", Springer-Verlag, W. D. Gonzalez and E. N. Parker, eds. (2016), 33 pages, 18 figure

Search for Direct CP Violation in B -> K pi Decays

We search for direct CP violation in flavor specific B -> K pi decays by measuring the rate asymmetry between charge conjugate modes. The search is performed on a data sample of 11.1 million B B bar events recorded on the Upsilon(4S) resonance by the Belle experiment at KEKB. We measure 90% confidence intervals in the partial rate asymmetry A_CP of -0.25 < A_CP(K-/+ pi+/-) < 0.37, -0.40 < A_CP(K-/+ pi^0) < 0.36, and -0.53 < A_CP(K^0 pi-/+) < 0.82. By combining the K-/+ pi+/- and K-/+ pi^0 final states, we conclude that -0.22 < A_CP[K-/+(pi+/- + pi^0)] < 0.25 at the 90% confidence level.Comment: Submitted to PRD Rapid Communication

Measurement of Inclusive Production of Neutral Pions from Upsilon(4S) Decays

Using the Belle detector operating at the KEKB e+e- storage ring, we have measured the mean multiplicity and the momentum spectrum of neutral pions from the decays of the Upsilon(4S) resonance. We measure a mean of 4.70 +/- 0.04 +/- 0.22 neutral pions per Upsilon(4S) decay.Comment: 15 pages, 4 figs. Submitted to Phys.Rev.