T-Duality for Orientifolds and Twisted KR-Theory

D-brane charges in orientifold string theories are classified by the KR-theory of Atiyah. However, this is assuming that all O-planes have the same sign. When there are O-planes of different signs, physics demands a “KR-theory with a sign choice” which up until now has not been studied by mathematicians (with the unique exception of Moutuou, who did not have a specific application in mind). We give a definition of this theory and compute it for orientifold theories compactified on S ¹ and T ². We also explain how and why additional “twisting” is implemented. We show that our results satisfy all possible T-duality relationships for orientifold string theories on elliptic curves, which will be studied further in subsequent work.     

Anomalous acid proton self-diffusion in N(CH3)4HSO4 — A candidate for proton superionic conductivity

The appearance of a “liquid-like” proton T₂ component above 100°C and the relatively high value of the proton self-diffusion coefficient D = (5–8) × 10^-7cm²sec^-1 between 175°C and 200°C demonstrate the onset of a super-ionic state in N(CH₃)₄HSO₄. The ratio between the “liquid” and “solid” like components shows that acid protons are responsible for the high ionic conductivity.     

On the prediction of impact noise,V: The noise from drop hammers

In earlier papers in this series, the concepts of “acceleration” and “ringing” noise have been studied in relation to impact machines, and values of radiation efficiency have been obtained for the various types of structural components. In the work reported in this paper the predicted and measured noise radiation from a drop hammer, both in full-scale and in $\text{1}\text{3}\text{-}\text{scale}$ model form, were examined. It is found that overall noise levels (L_eq per event) can be predicted from vibration measurements to within ± 1·5 dB, and to within ±2·5 dB in one-third octave bands. In turn this has permitted noise reduction techniques to be examined by studies of local component vibration levels rather than overall noise, a method which provides considerable enlightenment at the design stage. It is shown that on one particular drop hammer, the noise energy is shared surprisingly uniformly over four or five sources, and that when these have been reduced, the overall noise reduction is severely limited by the “acceleration” noise from the “tup” or “hammer” itself. As this is difficult to eliminate without a basic change in forging technology, it follows that “tup” enclosure or modification of the sharpness of the final “hard” impact are the only means available for any serious noise reduction. Also indicated is the reliability of using model techniques, suitably scaled in frequency and impulse magnitude, in developing machinery with impact characteristics.     

Bounds on new contact interactions from future e+e− colliders

A systematic study of the “reach” for contact interactions as a probe for new physics at future e⁺e⁻ colliders is performed. A large energy range is considered, from PETRA/PEP energies at the lower end, via the Z⁰ peak (SLC/LEP-I) and LEP-II, up to the TeV regime of a potential future linear e⁺e⁻ collider. Lower bounds on the compositeness scale Λ for leptons are calculated for Bhabha scattering and μ-pair production using realistic assumptions on the expected luminosities and detector performances. The impact of longitudinal and transverse polarization is studied in detail. The “reach” corresponding to high rates at the Z⁰ peak is compared to the one obtained from running at higher energies. At LEP-II energies, a sensitivity to (lepton) substructure at the level of Λ ∼ 10 TeV is to be expected. At a 2 TeV e⁺e⁻ collider the sensitivity can be as large as 100 TeV.     

A bag-like model for kinematic corrections to structure functions

Within a hadron bag valence quarks have a distribution of momenta, which, at low energies allows the kinematic scaling violations in deep inelastic scattering to be calculated. Using a simple model for this distribution we can succesfully account for the data between 2 and 6 (GeV/c)². At higher momenta, “non-kinematic” effects are required.     

The critical exponent of nuclear fragmentation

Nuclei colliding at energies in the MeV’s break into fragments in a process that resembles a liquid-to-gas phase transition of the excited nuclear matter. If this is the case, phase changes occurring near the critical point should yield a “droplet” mass distribution of the form ≈A ^?T, with T (a critical exponent universal to many processes) within 2≤T≤3. This critical phenomenon, however, can be obscured by the finiteness in space of the nuclei and in time of the reaction. With this in mind, this work studies the possibility of having critical phenomena in small “static” systems (using percolation of cubic and spherical grids), and on small “dynamic” systems (using molecular dynamics simulations of nuclear collisions in two and three dimensions). This is done investigating the mass distributions produced by these models and extracting values of critical exponents. The specific conclusion is that the obtained values of T are within the range expected for critical phenomena, i.e. around 2.3, and the grand conclusion is that phase changes and critical phenomena appear to be possible in small and fast breaking systems, such as in collisions between heavy ions.     

Mechanisms underlying sonoporation: Interaction between microbubbles and cells

The past several decades have witnessed great progress in “smart drug delivery”, an advance technology that can deliver genes or drugs into specific locations of patients’ body with enhanced delivery efficiency. Ultrasound-activated mechanical force induced by the interactions between microbubbles and cells, which can stimulate so-called “sonoporation” process, has been regarded as one of the most promising candidates to realize spatiotemporal-controllable drug delivery to selected regions. Both experimental and numerical studies were performed to get in-depth understanding on how the microbubbles interact with cells during sonoporation processes, under different impact parameters. The current work gives an overview of the general mechanism underlying microbubble-mediated sonoporation, and the possible impact factors (e.g., the properties of cavitation agents and cells, acoustical driving parameters and bubble/cell micro-environment) that could affect sonoporation outcomes. Finally, current progress and considerations of sonoporation in clinical applications are reviewed also.     

Self-broadening of principal series lines of rubidium at high number densities and oscillator strengths

The self-broadening of principal series lines of rubidium and the corresponding oscillator strengths have been measured using a steel absorption tube heated up in an electric furnace. The line profiles were obtained from absorption measurements using a grating spectrograph of high resolution in the temperature range of 340–490 °C; the number densities varied from 5 · 10¹⁶ to 8 · 10¹⁷cm^?3. The half widths deduced from the absorption profiles disagree with the classical impact approximation based on dipole-dipole interaction but approach closely the asymptotic values of the quantum-mechanical Reinsberg theory and of the “short-range”-calculations of Presnyakov. Oscillator strengths for the higher series lines were evaluated from the spectra agreeing very well with the asymptoticn ^*?3-hydrogen-like slope of the values.     

A minimum photon “rest mass” — Using Planck's constant and discontinuous electromagnetic waves

Reasons for taking1/2h/c ² in cgs units as an equivalent in grams for the photon “rest mass” are given. Its numerical value of3.68×10 ^?48 g corresponds to the minimum mass equivalent energy for one half-cycle of an electromagnetic dipole field distribution, which is discontinuous. For the fluid models that are discussed, this field distribution corresponds somewhat to a hydrodynamic toroidal vortex which is stationary—if we use toroidal coordinates and assume that the ring origin has the radial velocity c, that the gauge is defined by the ring origin diameter, and that free space is represented by a two-fluid model (the fluids oppositely charged). There are mappings which can transform such toroidal entities (photons) into spherical ones. The toroidal entities are possible candidates for the role of “hidden variables.”     

Effect of solvent polarity on the Ultrasound Assisted extraction and antioxidant activity of phenolic compounds from habanero pepper leaves (Capsicum chinense) and its identification by UPLC-PDA-ESI-MS/MS

Phenolic compounds are secondary metabolites involved in plant adaptation processes. The development of extraction procedures, quantification, and identification of this compounds in habanero pepper (Capsicum chinense) leaves can provide information about their accumulation and possible biological function. The main objective of this work was to study the effect of the UAE method and the polarity of different extraction solvents on the recovery of phenolic compounds from C. chinense leaves. Quantification of the total phenolic content (TPC), antioxidant activity (AA) by ABTS⁺ and DPPH radical inhibition methods, and the relation between the dielectric constant (ε) as polarity parameter of the solvents and TPC using Weibull and Gaussian distribution models was analyzed. The major phenolic compounds in C. chinense leaves extracts were identified and quantified by UPLC-PDA-ESI-MS/MS. The highest recovery of TPC (24.39 ± 2.41 mg GAE g⁻¹ dry wt) was obtained using MeOH (50%) by UAE method. Correlations between TPC and AA of 0.89 and 0.91 were found for both radical inhibition methods (ABTS⁺ and DPPH). The Weibull and Gaussian models showed high regression values (0.93 to 0.95) suggesting that the highest phenolic compounds recovery is obtained using solvents with “ε” values between 35 and 52 by UAE. The major compounds were identified as N-caffeoyl putrescine, apigenin, luteolin and diosmetin derivatives. The models presented are proposed as a useful tool to predict the appropriate solvent composition for the extraction of phenolic compounds from C. chinense leaves by UAE based on the “ε” of the solvents for future metabolomic studies.     

Thermal effects in sputtering

Of the various sputtering phenomena taking place when solids are bombarded, two have been attributed to thermal effects. The first is prompt thermal sputtering, which can be understood in terms of vaporization from the impact region in accordance with a briefly lived temperature excursion. Doubt is cast on some of the experiments with elemental targets originally intended to demonstrate prompt thermal sputtering in that they involved sufficiently high temperatures as to permit normal vaporization. Work involving polyatomic ions incident on elements is also problematical but recent studies by the groups of De Vries and Husinsky in which dN/dE was measured with Na, Na₂O, and various halides appear to confirm the existence of prompt thermal sputtering. The second type of thermal effect, slow thermal sputtering, can be understood as due to vaporization from the impact region without the aid of a temperature excursion. Such vaporization is well documented with halides, where halogen is lost by electron sputtering and, for high enough target temperatures, the accumulating metal then gives rise to characteristic signals in the dN/dE spectra which we term “slow thermal sputtering”. For low enough target temperatures, halides tend to develop metallized surfaces. Oxides also show electron sputtering, and, as would be expected, there is a concurrent loss of metal at higher temperatures but metallization at lower temperatures. The yields with oxides are 10⁶–10⁸ lower than with halides.     

A study of reaction rates of (n, f ) , (n, \gamma) and (n, 2n) reactions in natU and 232Th by the neutron fluence produced in the graphite set-up (GAMMA-3) irradiated by 2.33 GeV deuteron beam

Spallation neutrons produced in the collision of a 2.33GeV deuteron beam with a large lead target are moderated by a thick graphite block surrounding the target and used to activate the radioactive samples of ^natU and Th put at three different positions, identified as holes “a”, “b” and “c” in the graphite block. Rates of the (n, f), (n, $ \gamma$ and (n, 2n) reactions in the two samples are determined using the gamma spectrometry. The ratios of the experimental reaction rates, R (n, 2n)/R (n, f), for ²³²Th and ^natU are estimated in order to understand the role of the (n, x n) kind of reactions in Accelerator-Driven Sub-critical Systems. For the Th-sample, the ratio is ～ 54 (10)% in the case of hole “a” and ～ 95 (57)% in the case of hole “b” compared to 1.73(20)% for hole “a” and 0.710(9)% for hole “b” in the case of the ^natU sample. Also the ratio of fission rates in uranium to thorium, ^natU (n, f)/ ²³²Th (n, f), is ～ 11.2 (17) in the case of hole “a” and 26.8(85) in hole “b”. Similarly, the ratio ²³⁸U (n, 2n)/ ²³²Th (n, 2n) is 0.36(4) for hole “a” and 0.20(10) for hole “b” showing that ²³²Th is more prone to the (n, x n) reaction than ²³⁸U . All the experimental reaction rates are compared with the simulated ones by generating neutron fluxes at the three holes from MCNPX 2.6c and making use of the LA150 library of cross-sections. The experimental and calculated reaction rates of all the three reactions are in reasonably good agreement. The transmutation power, P _norm as well as P _norm/P _beam of the set-up is estimated using the reaction rates of the (n, $ \gamma$ and (n, 2n) reactions for both the samples in the three holes and compared with some of the results of the “Energy plus Transmutation” set-up and TARC experiment.     

pep neutrino detection by a lithium detector as a direct way to seek oscillations of solar neutrinos

The high sensitivity of a lithium detector to pep and ⁷Be neutrinos renders a radiochemical lithium detector a powerful tool for seeking solar-neutrino oscillations. The first phase of the lithium experiment with an apparatus involving 10 t of metallic lithium will allow collecting data within 1 yr of measurements to provide very definite information about a MSW SMA solution. The second phase with ten modules 10 t each will measure the semiannual variations of the signal, whereby the contributions of pep and ⁷Be lines will be weighted, which will give “smoking-gun” evidence for the “just-so” solution for large mixing angles and Δm ² about 10^?10–10^?9 eV². If both regions are not confirmed, the results of the lithium detector can be interpreted in favor of the MSW LMA solution.     

Die Anregung von Rb+ in einem Kryptongitter durch die plötzliche Zentralfeldänderung beim β-Zerfall von Kr85

After theβ-decay of Kr⁸⁵ in solid Krypton the Rb⁺-ion, resulting from this decay, is excited in 4p⁵ 5p(J=0)-states with a certain probability. The photon-spectrum, due to dipole-transitions from these excited states, selected with narrow-band-filters and measured in coincidence with the emittedβ-particles, shows narrow bands (“lines”) and broad bands. The “lines” are not shifted with respect to the atomic Rb⁺-lines, whereas each broad band can be interpreted as a component of each “line”, being shifted about 800 cm^?1 to the blue end of the spectrum. The measured lifetime of the excited states is (7.5±0.5) ns in the “lines” and (5±0.5) ns in the bands, the measured excitation-probability is (8±1) · 10^?2 perβ-decay. A calculation of the magnitude of the spectral shift and the excitation-probability with the LCAO-approximation is made under the following assumptions: the “lines” are due to Rb⁺-ions on regular crystal-sites; the shifted bands are caused by Rb⁺-ions, trapped at octaedral interstitial-sites, after being displaced from their original regular crystal-sites by theβ-recoil. A comparison between the experimental and calculated values confirms these assumptions.     

M1 Character of unresolved continuum transitions from X-ray multiplicity measurements

We have measured the X-ray multiplicities of the transitions deexciting the quasi-continuum region as a function of the input spin for deformed and transitional erbium isotopes obtained in (⁴⁰Ar,xn) reactions. Combined withγ-ray angular distribution studies, these measurements clearly show the occurrence of a magnetic dipole component in the energy region 300–800keV. The spin dependence of this “bump” is quite different in deformed and transitional nuclei. In the latter case, a sudden increase in the quasi-continuumK electron multiplicity arises for spins higher than 35? and is strongly correlated to the occurrence of collective modes in these nuclei at the same spins. It is suggested to correspond to collective behavior of bands built on yrast states of single particle nature.     

A “comb” structure measurement of a micrometer displacement in laser plasma propulsion

A “comb” structure of beam intensity distribution is achieved to measure target displacements at the micrometer level in laser plasma propulsion experiments. Compared with single-beam and double-beam detection, the “comb” structure is more suitable for a thin film targets with a velocity lower than 10^?2 m/s. Combined with a light-electric monitor, the “comb” structure can be used to measure a velocity range from 10^?3 to 1 m/s. Using this “comb” structure, the coupling coefficient of aluminum ablated by nanosecond pulse laser in air is determined and compared. The results indicate that this “comb” structure is an effective experimental approach.     

Tests of various models for the weak decays of heavy flavour states

It is discussed how two models which were proposed to explain the lifetime difference betweenD ⁰ andD ⁺ mesons can be subjected to further tests. These two models are the “SU (4) 20-plet dominance” model and the “gluon bremstrahlung” model forW exchange. The tests can be performed by studying inclusive decays—e.g.,F ⁺ lifetime or semi-leptonic branching ratio—or special exclusive modes in the non-leptonic and semileptonic decays. It is suggested thatF ⁺ semi-leptonic decays can lead to glueball production. The decays of bottom mesons are discussed in this context, too.     

Solid-state 13C NMR and synchrotron SAXS/WAXS studies of uniaxially-oriented polyethylene

We report solid-state ¹³C NMR and synchrotron wide-and small-angle X-ray scattering experiments (WAXS, SAXS) on metallocene linear low density polyethylene films (e.g., Exceed™ 1018 mLLDPE; nominally 1 MI, 0.918 density ethylene-hexene metallocene copolymer) as a function of uniaxial draw ratio, λ. Combined, these experiments provide an unambiguous, quantitative molecular view of the orientation of both the crystalline and amorphous phases in the samples as a function of draw. Together with previously reported differential scanning calorimetry (DSC), gas transport measurements, transmission electron microscopy (TEM), optical birefringence, small angle X-ray scattering (SAXS) as well as other characterization techniques, this study of the state of orientation in both phases provides insight concerning the development of unusually high barrier properties of the most oriented samples (λ=10). In this work, static (non-spinning) solid-state NMR measurements indicate that in the drawn Exceed^TM films both the crystalline and amorphous regions are highly oriented. In particular, chemical shift data show the amorphous phase is comprised increasingly of so-called “taut tie chains” (or tie chains under any state of tautness) in the mLLDPE with increasing draw ratio – the resonance lines associated with the amorphous phase shift to where the crystalline peaks are observed. In the sample with highest total draw (λ=10), virtually all of the chains in the non-crystalline region have responded and aligned in the machine (draw) direction. Both monoclinic and orthorhombic crystalline peaks are observed in high-resolution, solid-state magic-angle spinning (MAS) NMR measurements of the oriented PE films. The orientation is comparable to that obtained for ultra-high molecular weight HDPE fibers described as “ultra-oriented” in the literature. Furthermore, the presence of a monoclinic peak in cold-drawn samples suggests that there is an appreciable internal stress associated with the LLDPE. The results are confirmed and independently quantified by Herman's Orientation Function values derived from the WAXS measurements. The degree of orientation approaches theoretically perfect alignment of chains along the draw direction. We deduce from this observation that a high fraction of the non-crystalline chains are either tie chains that directly connect adjacent lamellae or are interlocking loops from adjacent lamellae. In either case, the chains are load-bearing and are consistent with the idea of “taut tie chains”. We note that transmission electron micrographs recorded for the ultra-oriented Exceed showed the lamellae are often appreciably thinner and shorter than they are for cast or blown Exceed 1018. Combined with higher crystallinity, the thinner lamellae statistically favor more tie chains. Finally, the remarkably large decrease in permeability of the λ=10 film is primarily attributed to the high degree of orientation (and loss of entropy) of the amorphous phase.     

The diffractive component of multihadron production processes at high energies

Multihadron production at high energies proceeds through two mechanisms: A nondiffractive mechanism of a general multiperipheral nature and a diffractive mechanism. Assuming that the diffractive mechanism is dominated at present energies (s < 3000 BeV²) by single diffraction excitation we explore its theoretical and phenomenological implications. In particular we study the question of the rising total cross section. We show that “high mass diffraction excitation” leads to the formation of a central plateau in the inclusive single pion distribution and that the height of this plateau rises with energy and obeys scaling when normalized by the total cross section. We compute the multiplicity distribution for the diffractive component, and deduce the properties of the average multiplicity, its moments, and the statistical mechanics analogue of the “diffractive” Feynman gas. Two-particle correlations are computed and shown to be of a long range nature. Finally we outline an “improved” two component model into which some of the detailed features of the diffractive part are incorporated.     

Amorphous GaP produced by ion implantation

Two types of non-crystalline states (“disordered” and “amorphous”) of GaP were produced by using ion implantation and post annealing. A structural-phase-transition-like annealing behaviour from the “disordered” state to the “amorphous” state was observed.The ion dose dependence and the annealing behaviour of the atomic structure of GaP implanted with 200 keV ? N⁺ ions were studied by using electron diffraction, backscattering and volume change measurements. The electronic structure was also investigated by measuring optical absorption and electrical conductivity.The implanted layer gradually loses the crystalline order with the increase of the nitrogen dose.The optical absorption coefficient α and electric conductivity σ of GaP crystals implanted with 200 keV?N⁺ ions of 1 × 10¹⁶ cm^?2 were expressed as αhν = C(hν ? E₀)ⁿ and log $\text{σ = A ? BT}{}^{\mathrm{<mtext>-</mtext><mtext>1</mtext><mtext>4</mtext>}}$, respectively. Moreover, the volume of the implanted layer increased about three percent and the electron diffraction pattern was diffused halo whose intensity monotonically decreases along the radial direction. These results indicate that the as-implanted layer has neither a long range order nor a short range order (“disordered state”).In the sample implanted at 1 × 10¹⁶ cm^?2, a structural phase-transition-like annealing stage was observed at around 400°C. That is, the optical absorption coefficient α abruptly fell off from 6 × 10⁴ to 7 × 10³ cm^?1 and the volume of the implanted layer decreased about 2% within an increase of less than 10 degrees in the anneal temperature. Moreover, the short range order of the lattice structure appeared in the electron diffraction pattern. According to the backscattering experiment, the heavily implanted GaP was still in the non-crystalline state even after annealing.These facts lead us to believe that heavily implanted GaP, followed by annealing at around 400°C, is in the “amorphous” state, although as-implanted Gap is not in the “amorphous” state but in the “disordered” state.