The progressive nature of Wallerian degeneration in wild-type and slow Wallerian degeneration (Wld<Superscript>S</Superscript>) nerves

Background  

The progressive nature of Wallerian degeneration has long been controversial. Conflicting reports that distal stumps of injured axons degenerate anterogradely, retrogradely, or simultaneously are based on statistical observations at discontinuous locations within the nerve, without observing any single axon at two distant points. As axon degeneration is asynchronous, there are clear advantages to longitudinal studies of individual degenerating axons. We recently validated the study of Wallerian degeneration using yellow fluorescent protein (YFP) in a small, representative population of axons, which greatly improves longitudinal imaging. Here, we apply this method to study the progressive nature of Wallerian degeneration in both wild-type and slow Wallerian degeneration (Wld^S) mutant mice.     

Detection of taurine in biological tissues by (33)S NMR spectroscopy.

The potential of (33)S NMR spectroscopy for biochemical investigations on taurine (2-aminoethanesulfonic acid) is explored. It is demonstrated that (33)S NMR spectroscopy allows the selective and unequivocal identification of taurine in biological samples. (33)S NMR spectra of homogenated and intact tissues are reported for the first time, together with the spectrum of a living mollusc. Emphasis is placed on the importance of choosing appropriate signal processing methods to improve the quality of the (33)S NMR spectra of biological tissues.     

Stark broadening of S(III) and S(IV) lines

Measurements of the Stark widths of doubly and triply ionized sulfur lines were made in a low pressure, pulsed arc plasma of electron density 5.1 × 10¹⁶ cm^-3 at an electron temperature of 28, 500°K. The experimental S(III) and S(IV) Stark-profile halfwidths were compared with calculated values obtained with Griem's semiempirical and approximate semiclassical approach. The experimental results agree better with the semiclassical results.     

Photon transitions in Upsilon(2S) and Upsilon(3S) decays

We have studied the inclusive photon spectra in Upsilon(2S) and Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S) --> gammachi(bJ)(1P) and Upsilon(3S) --> gammachi(bJ)(2P) (J = 0, 1, 2). We measure the rate for a rare E1 transition Upsilon(3S) --> gammachi(b0)(1P) for the first time. We also set upper limits on the rates for the hindered magnetic dipole (M1) transitions to the eta(b)(1S) and eta(b)(2S) states.     

Theoretical study of energy transfer in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions

We present results of theoretical studies of the non-resonant excitation transfer in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions at thermal collision energies. Rb₂ adiabatic molecular terms correlating with the 5S+7S, 5S+5D and 5P+5P states of separated atoms were calculated for internuclear distances R > 20 a.u. using asymptotic approximation. Mechanisms of collisional population and quenching of the 5D state were treated on the basis of the computed molecular terms, and the respective cross-sections were calculated. Theoretical cross-sections are in good agreement with the experimental values at thermal collision energies ( K). Received 13 November 1998 and Received in final form 22 November 1999     

Observation of anomalous upsilon(1S)pi+pi(-) and upsilon(2S)pi+pi(-) production near the upsilon(5S) resonance

We report the first observation of e;{+}e;{-}-->Upsilon(1S)pi;{+}pi;{-}, Upsilon(2S)pi;{+}pi;{-}, and first evidence for e;{+}e;{-}-->Upsilon(3S)pi;{+}pi;{-}, Upsilon(1S)K+K-, near the peak of the Upsilon(5S) resonance at sqrt[s] approximately 10.87 GeV. The results are based on a data sample of 21.7 fb;{-1} collected with the Belle detector at the KEKB e;{+}e;{-} collider. Attributing the signals to the Upsilon(5S) resonance, the partial widths Gamma(Upsilon(5S)-->Upsilon(1S)pi;{+}pi;{-})=0.59+/-0.04(stat)+/-0.09(syst) MeV and Gamma(Upsilon(5S)-->Upsilon(2S)pi;{+}pi;{-})=0.85+/-0.07(stat)+/-0.16(syst) MeV are obtained from the observed cross sections. These values exceed by more than 2 orders of magnitude the previously measured partial widths for dipion transitions between lower Upsilon resonances.     

31P double-quantum solid-state NMR study of phosphoroorganic compounds with (O)P-O-P-(O), (S)P-O-P(S) and (S)P-S-P(O) unit

In this work we have tested applicability of the commonly used double quantum recoupling sequence POST-C7 to study of ³¹P–³¹P geometrical constraints for phosphoroorganic model compounds with different chemical shift anisotropy (CSA) and distinct molecular dynamics in the crystal lattice. Our results clearly show that even with large CSA, POST-C7 gives good efficiency of ³¹P double-quantum excitations. Moreover, large amplitude molecular motion only slightly disturb ³¹P build-up curve. χ² error analysis is used for verification of values and orientations of chemical shift tensors (CST) parameters employed for simulation of POST-C7 buildup curves.     

Observation of Upsilon(4S) decays to pi(+)pi(-)Upsilon(1S) and pi(+)pi(-)Upsilon(2S)

Observation of Upsilon(4S) decays to pi(+)pi(-)C and pi(+)pi(-)Upsilon(2S)We present the first measurement of Upsilon(4S) decays to pi(+)pi(-)Upsilon(1S) based on a sample of 230 x 106(4S) mesons collected with the BABAR detector. We measure the product branching fractions Beta(Upsilon(4S) --> pi(+)pi(-)Upsilon(1S)) x BetaUpsilon(1S) --> mu(+)mu(-) = (2.23 +/- 0.25(stat) +/- 0.27(syst))x 10(-6) and Beta(Upsilon(4S) --> pi(+)pi(-)Upsilon(2S) x Beta(Upsilon(2S) --> mu(+)mu(-))=(1.69 +/-0.26(stat) +/- 0.20(syst)) x 10(-)6, from which we derive the partial widths Gamma(Upsilon(4S) --> pi(+)pi(-)Upsilon(1S))=(1.8 +/-0.4) keV and Gamma(Upsilon(4S) --> pi(+)pi(-)Upsilon(2S))=(2.7 +/- 0.8) keV.     

Observation of the eta(c)(2S) in Exclusive B-->KK(S)K-pi(+) Decays

We report the observation of a narrow peak in the K(S)K-pi(+) invariant mass distribution in a sample of exclusive B-->KK(S)K-pi(+) decays collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider. The measured mass of the peak is M=3654+/-6(stat)+/-8(syst) MeV/c(2), and we place a 90% confidence level upper limit on the width of Gamma<55 MeV/c(2). The properties agree with heavy-quark potential model expectations for the eta(c)(2S) meson, the n=2 singlet S charmonium state.     

Calculated Stark widths of isolated S(III) and S(IV) lines

Calculations have been performed on the electron-impact broadening of isolated lines from doubly-ionized and triply-ionized sulphur emitted from a plasma of electron density 10¹⁷ cm^-3 and temperature 28,500°K. These have been compared with results of measurements performed by Plati?a, Popovi?, Dimitrijevi?, and Konjevi? on a low-pressure, pulsed arc. Good overall agreement has been obtained for both ionization stages, in confirmation of our earlier conclusions based on a similar comparison for oxygen ion lines. The present calculations have been compared with calculations based upon two simplified models of Griem and the classical-path approximation of Sahal-Bréchot. Our calculated widths are in better agreement with experiment than with values obtained from the first two models; for the two multiplets, where comparison is possible, good agreement is found with the widths obtained by Sahal-Bréchot. We conclude that the present model, whereby the effective Gaunt factor is calculated, is capable of predicting reliable values for the Stark widths of isolated ion lines. Comparison with experiment [for S(III) indicates that, provided a sufficiently complete set of perturbing levels is used in the calculations, the present formula for ? may also be used for below-threshold energies in the determination of the elastic contribution to the broadening. For S(IV), an ambiguity remains in this regard, owing chiefly to a scarcity of available experimental data.     

On the elasticity of transverse isotropic soft tissues (L)

Quantitative elastography techniques have recently been developed to estimate the shear modulus μ of soft tissues in vivo. In the case of isotropic and quasi-incompressible media, the Young's modulus E is close to 3 μ, which is not true in transverse anisotropic tissues such as muscles. In this letter, the transverse isotropic model established for hexagonal crystals is revisited in the case of soft solids. Relationships between elastic constants and Young's moduli are derived and validated on experimental data found in the literature. It is shown that 3 μ(⊥) ≤ E(⊥) ≤ 4 μ(⊥) and that E(//) cannot only be determined from the measurements of μ(//) and μ(⊥).     

Extremely slow charge fluctuations in the metallic state of the two-dimensional molecular conductor theta-(BEDT-TTF)2RbZn(SCN)4

Large charge disproportionation has been confirmed in the metallic state of a 1/4-filled organic conductor theta-(BEDT-TTF)2RbZn(SCN)4 by means of 13C-NMR analysis on a selectively 13C-enriched single crystal sample. By comparing the homogeneous and inhomogeneous linewidths, the temperature dependence of the extremely slow dynamics of charge fluctuations has been determined first. The exotic nature of the metallic state of this salt is discussed.     

Reflection of slow electrons from the (110) face of a tungsten crystal

Secondary-electron emission from the (110) face of tungsten was studied at low primaryelectron energies (1–30 eV). The electrons reflected from the target surface were distinguished by analyzing the retardation curves of the secondary particles found in retardation in a spherical capacitor. The reflection coefficient R for an electron energy of about 1 eV is 0.08; it increases with increasing energy, reaching a maximum (0.34) at 3.3 eV; then it decreases; passing through a low maximum near 13 eV. Contamination of the target surface shifts the maximum by 0.7 eV and reduces the maximum reflection coefficient to 0.22. The total secondary-emission yield at the clean surface also reaches a maximum at 3.3 eV. Above 13 eV, increases, reaching a value of 0.5 at 30 eV. The value for a contaminated target is lower than that for a clean target. On a clean target the yield corresponding to true secondaries and inelastically reflected electrons remains at 0.1 for primary energies below 5 eV (down to 1 eV), while the value of this yield for a contaminated surface is nearly 0 for a primary energy of 1 eV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 88–94, November, 1970.The authors thank Prof essor G. N. Shuppe for his interest in this study, A. Kashetov for assistance in the experiments, and master glassblower G. S. Rubets for constructing the apparatus.     

Branching fraction and CP asymmetries of B0-->K0(S)K0(S)K0(S)

We present measurements of the branching fraction and time-dependent CP-violating asymmetries in B0-->K0(S)K0(S)K0(S) decays based on 227 x 10(6) Upsilon4S-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We obtain a branching fraction of (6.9(+0.9)(-0.8)+/-0.6) x 10(-6), and CP asymmetries C=-0.34(+0.28)(-0.25)+/-0.05 and S=-0.71(+0.38)(-0.32)+/-0.04, where the first uncertainties are statistical and the second systematic.     

Minigap Suppression in S(N/F)S Junctions

JETP Letters - We consider a long diffusive Josephson junction where the weak link is a thin (normal metal (N)–ferromagnet (F)) bilayer (N and F form parallel links between superconductors...     

Dielectron widths of the Gamma(1S,2S,3S) resonances

We determine the dielectron widths of the Gamma(1S), Gamma(2S), and Gamma(3S) resonances with better than 2% precision by integrating the cross section of e+e- -->Gamma over the e+e- center-of-mass energy. Using e+e- energy scans of the Gamma resonances at the Cornell Electron Storage Ring and measuring Gamma production with the CLEO detector, we find dielectron widths of 1.252+/-0.004(sigma(stat))+/-0.019(sigma(syst)) keV, 0.581+/-0.004+/-0.009 keV, and 0.413+/-0.004+/-0.006 keV for the Gamma(1S), Gamma(2S), and Gamma(3S), respectively.