The Gordon-Haus effect for modified NLS solitons

Random jitter in the soliton arrival time (the Gordon-Haus effect) is analyzed for solitons being solutions of the integrable modified nonlinear Schroedinger equation. It is shown that the mean square fluctuation of the soliton position depends on the soliton parameters which can be properly adjusted to suppress the Gordon-Haus jitter.Comment: LaTeX, 7 pages, 3 figures, to be published in Europhys. Let

Measurement of 1.7 to 74 MeV polarised gamma rays with the HARPO TPC

Current {\gamma}-ray telescopes based on photon conversions to electron-positron pairs, such as Fermi, use tungsten converters. They suffer of limited angular resolution at low energies, and their sensitivity drops below 1 GeV. The low multiple scattering in a gaseous detector gives access to higher angular resolution in the MeV-GeV range, and to the linear polarisation of the photons through the azimuthal angle of the electron-positron pair. HARPO is an R&D program to characterise the operation of a TPC (Time Projection Chamber) as a high angular-resolution and sensitivity telescope and polarimeter for {\gamma} rays from cosmic sources. It represents a first step towards a future space instrument. A 30 cm cubic TPC demonstrator was built, and filled with 2 bar argon-based gas. It was put in a polarised {\gamma}-ray beam at the NewSUBARU accelerator in Japan in November 2014. Data were taken at different photon energies from 1.7 MeV to 74 MeV, and with different polarisation configurations. The electronics setup is described, with an emphasis on the trigger system. The event reconstruction algorithm is quickly described, and preliminary measurements of the polarisation of 11 MeVphotons are shown.Comment: Proceedings VCI201

Disintegration of lysosomes mediated by GTP γS-treated cytosol: Possible involvement of phospholipases

金沢大学附属病院薬剤部We showed previously that cytosol treated with guanosine 5\u27-O-(3-thiotriphosphate) (GTP-γS) disintegrated lysosomes in vitro in time-, temperature-, and dose-dependent manners. This also requires ATP, however, the latter can be substituted with deoxy-ATP, ADP, or ATPγS, suggesting no requirement of ATP hydrolysis. The lysis was inhibited by several chemical modifiers, including N-ethylmaleimide, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, and 4,4\u27-diisothiocyanatostilbene-2,2\u27-disulfonic acid, and by various phospholipase inhibitors (trifluoperazine, p-bromophenacyl bromide, nordihydroguaiaretic acid, W-7, primaquine, compound 48/80, neomycin, and gentamicin), but not by ONO-RS-082, an inhibitor of phospholipase A2. The reaction was also inhibited by phospholipids (phosphatidylinositol, phosphatidylserine, phosphatidic acid, and phosphatidylcholine) and diacylglycerol. Among the phospholipase A2 hydrolysis products of phospholipids, unsaturated fatty acids (oleate, linoleate, and arachidonate) and lysophospholipid (lysophosphatidylcholine) by themselves broke lysosomes down directly, whereas saturated fatty acids (palmitate and stearate) had little effect. We found that GTPγS-stimulated cytosolic phospholipase A2 activity was highly sensitive to ONO-RS-082. These results suggest the participation of phospholipase(s), though not cytosolic phospholipase A2, in the GTPγS-dependent lysis of lysosomes

Slow group velocity and Cherenkov radiation

We theoretically study the effect of ultraslow group velocities on the emission of Vavilov-Cherenkov radiation in a coherently driven medium. We show that in this case the aperture of the group cone on which the intensity of the radiation peaks is much smaller than that of the usual wave cone associated with the Cherenkov coherence condition. We show that such a singular behaviour may be observed in a coherently driven ultracold atomic gas.Comment: 4 pages, 4 figure

Study of CP Property of the Higgs at a Photon Collider using γγ→ttˉ→lX\gamma\gamma\to t\bar t\to l X

We study possible effects of CP violation in the Higgs sector on $t\bar t$ production at a $\gamma\gamma$-collider. These studies are performed in a model-independent way in terms of six form-factors $\{\Re(S_{\gamma}), \Im(S_{\gamma}), \Re(P_{\gamma}), \Im(P_{\gamma}), S_t, P_t\}$ which parametrize the CP mixing in the Higgs sector, and a strategy for their determination is developed. We observe that the angular distribution of the decay lepton from $t/\bar t$ produced in this process is independent of any CP violation in the $tbW$ vertex and hence best suited for studying CP mixing in the Higgs sector. Analytical expressions are obtained for the angular distribution of leptons in the c.m. frame of the two colliding photons for a general polarization state of the incoming photons. We construct combined asymmetries in the initial state lepton (photon) polarization and the final state lepton charge. They involve CP even ($x$'s) and odd ($y$'s) combinations of the mixing parameters. We study limits up to which the values of $x$ and $y$, with only two of them allowed to vary at a time, can be probed by measurements of these asymmetries, using circularly polarized photons. We use the numerical values of the asymmetries predicted by various models to discriminate among them. We show that this method can be sensitive to the loop-induced CP violation in the Higgs sector in the MSSM.Comment: 15 pages, 9 figures added one referenc

New magnetic intermediate state, "B - phase, " in the cubic chiral magnet MnSi

It is well known that the archetype chiral magnet MnSi stabilizes a skyrmion lattice, termed "A-phase, "in a narrow temperature range in the vicinity of the paramagnetic boundary around Tc ~29 K and Hc ~2 kOe. Recently, it has been predicted that at much lower temperatures below Tc, the conical helicoid and the forced ferromagnetic (FFM) states could be separated by a new "unknown state."In order to detect this "unknown state, "we explored the phase diagram of MnSi oriented single crystals as a function of the d.c. magnetic field (H - dc) and the temperature (T) by using a.c. magnetization measurements. For H - dc¿ , we observed a new region, termed "B-phase, "in the magnetic phase diagram, characterized by a flat-valley-like anomaly on the in-phase component of the a.c. magnetization (m'), over 3.5 = Hdc = 6.2 kOe just below the low temperature (T or , revealing that the magnetic anisotropy could play a role in the stabilization of the phase. The "B-phase"could be compatible with the theoretical predictions if the new magnetic state is supposedly related with a relative reorientation of the four helices in MnSi