Magnetic and axial-vector transitions of the baryon antidecuplet

We report the recent results of the magnetic transitions and axial-vector transitions of the baryon antidecuplet within the framework of the chiral quark-soliton model. The dynamical model parameters are fixed by experimental data for the magnetic moments of the baryon octet, for the hyperon semileptonic decay constants, and for the singlet axial-vector constant. The transition magnetic moments $\mu_{\Lambda\Sigma}$ and $\mu_{N\Delta}$ are well reproduced and other octet-decuplet and octet-antidecuplet transitions are predicted. In particular, the present calculation of $\mu_{\Sigma\Sigma^*}$ is found to be below the upper bound $0.82\mu_N$ that the SELEX collaboration measured very recently. The results explains consistently the recent findings of a new $N^*$ resonance from the GRAAL and Tohoku LNS group. We also obtain the transition axial-vector constants for the $\Theta^+\to KN$ from which the decay width of the $\Theta^{+}$ pentaquark baryon is determined as a function of the pion-nucleon sigma term $\Sigma_{\pi N}$. We investigate the dependence of the decay width of the $\Theta^{+}$ on the $g_{A}^{(0)}$, with the $g_{A}^{(0)}$ varied within the range of the experimental uncertainty. We show that a small decay width of the $\Theta^{+}\to KN$, i.e. $\Gamma_{\Theta KN} \leq 1$ MeV, is compatible with the values of all known semileptonic decays with the generally accepted value of $g_{A}^{(0)} \approx 0.3$ for the proton.Comment: 8 pages, 5 figures, Talk given at the Yukawa International Seminar (YKIS) 2006, "New frontiers in QCD", Kyoto, Japan, 20 Nov. - 8 Dec. 200

Magnetic moments of exotic pentaquark baryons

In this talk, we present our recent investigation on the magnetic moments of the exotic pentaquark states, based on the chiral quark-soliton model, all relevant intrinsic parameters being fixed by using empirical data.Comment: 5 pages, 1 figure, a talk presented at the 10th International Conference on Baryons (Baryons04), Palaiseau, October 25-29, 200

Ultimately short ballistic vertical graphene Josephson junctions

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale.open113435sciescopu

The effect of phytosphingosine isolated from Asterina pectinifera on cell damage induced by mite antigen in HaCaT cell and antibacterial activity against Staphylococcus aureus

The current study was to investigate the positive protective effects of phytosphingosine (PS) against mite antigen and Staphylococcus aureus, etiological causes of an atopic dermatitis. To achieve this aim, PS was isolated from starfish, Asterina pectinifera, using high-performance liquid chromatography and was elucidated with nuclear magnetic resonance spectrometry. In the present experiment, PS, which ranged from 1 to 5 µM could protect the HaCaT cell against injuries caused by stimulation to 10 µg/ml mite antigen for 1 h, followed by incubation with serum-free medium for 24 h, which resembled the excitotoxin in vivo system. Furthermore, PS which was isolated from starfish could significantly inhibit the growth of S. aureus. In conclusion, this study demonstrated the protective effect of PS on excitotoxic damage against mite antigen and S. aureus through suppressing the excessive disruption of differentiation and exhibiting antibacterial capacity. This result implicated that the application of PS isolated from starfish might be a promising therapeutic option of atopic dermatitis

Tuning Locality of Pair Coherence in Graphene-based Andreev Interferometers

We report on gate-tuned locality of superconductivity-induced phase-coherent magnetoconductance oscillations in a graphene-based Andreev interferometer, consisting of a T-shaped graphene bar in contact with a superconducting Al loop. The conductance oscillations arose from the flux change through the superconducting Al loop, with gate-dependent Fraunhofer-type modulation of the envelope. We confirm a transitional change in the character of the pair coherence, between local and nonlocal, in the same device as the effective length-to-width ratio of the device was modulated by tuning the pair-coherence length xi(T) in the graphene layer.open1133sciescopu

Search for Boosted Dark Matter at ProtoDUNE

We propose the first experimental test of the inelastic boosted dark matter hypothesis, capitalizing on the new physics potential with the imminent data taking of the ProtoDUNE detectors. More specifically, we explore various experimental signatures at the cosmic frontier, arising in boosted dark matter scenarios, i.e., relativistic, inelastic scattering of boosted dark matter often created by the annihilation of its heavier component which usually comprises of the dominant relic abundance. Although features are unique enough to isolate signal events from potential backgrounds, vetoing a vast amount of cosmic background is rather challenging as the detectors are located on the ground. We argue, with a careful estimate, that such backgrounds nevertheless can be well under control by performing dedicated analyses after data acquisition. We then discuss some phenomenological studies which can be achieved with ProtoDUNE, employing a dark photon scenario as our benchmark dark-sector model.Comment: Supplemental material include

Quasimonoenergetic electron beam generation by using a pinholelike collimator in a self-modulated laser wakefield acceleration

A relativistic electron bunch with a large charge (>2 nC) was produced from a self-modulated laser wakefield acceleration configuration. For this experiment, an intense laser beam with a peak power of 2 TW and a duration of 700 fs was focused in a supersonic He gas jet, and relativistic high-energy electrons were observed from the strong laser-plasma interaction. By passing the electron bunch through a small pinholelike collimator, we could generate a quasimonoenergetic high-energy electron beam, in which electrons within a cone angle of 0.25 mrad (f/70) were selected. The beam clearly showed a narrow-energy-spread behavior with a central energy of 4.3 MeV and a charge of 200 pC. The acceleration gradient was estimated to be about 30 GeV/m. Particle-in-cell simulations were performed for comparison study and the result shows that both the experimental and simulation results are in good agreement and the electron trapping is initiated by the slow beat wave of the Raman backward wave and the incident laser pulse.open181

A Review of Brittleness Index Correlations for Unconventional Tight and Ultra-Tight Reservoirs

Brittleness is a key parameter in the development of the unconventional shale and tight carbonate reservoirs as it plays a role in the design of the hydraulic fractures as well as the selection of the sweet-spot locations for perforation and fracture initiation. The brittleness index (BI) is utilized to indicate if the formation rocks are brittle, which are preferable to form a complex network of fractures, or ductile, which are occasionally desirable to seal the fractures from growing. However, there is a wide variety of BI methods in the literature that lead to inconclusive BI values. The Mineral-based brittleness index (MBI), which is a method based on the mineral composition of the formation, can be derived from mineral well logging data or laboratory core testing. Another approach in describing the brittleness is the Fracability Index (FI), which is a combination of Young’s modulus and Poisson’s ratio. Differentiation is also made between the dynamic FI, which is calculated from well logging data, and the static FI, which is derived from laboratory core testing such as uniaxial compressive strength, Brazilian tensile strength and triaxial testing. Hence, to understand the complexity of the brittleness, it is crucial to consider all dependencies such as the lithology, mineral composition, TOC, porosity, temperature and pressure amongst others. In this work, a comprehensive review and analysis of the existing equations and correlations for the calculation of the MBI and FI was conducted. These methods were applied on different low porosity and low permeability rocks. A thorough comparison has also been conducted between the MBI and FI correlations as well as between the dynamic FI and the static FI to ultimately clarify and improve the definition of brittleness as a function of lithology. High content of quartz and carbonates result in high values of MBI, and high Young’s modulus values yield high FI values. On the other hand, high clay content and high porosity lead to low MBI values

Seasonal variations in the aragonite saturation state in the upper open-ocean waters of the North Pacific Ocean

Seasonal variability of the aragonite saturation state ((AR)) in the upper (50m and 100m depths) North Pacific Ocean (NPO) was investigated using multiple linear regression (MLR). The MLR algorithm derived from a high-quality carbon data set accurately predicted the (AR) of evaluation data sets (three time series stations and P02 section) with acceptable uncertainty (<0.1(AR)). The algorithm was combined with seasonal climatology data, and the estimated (AR) varied in the range of 0.4-0.6 in the midlatitude western NPO, with the largest variation found for the tropical eastern NPO. These marked variations were largely controlled by seasonal changes in vertical mixing and thermocline depth, both of which determine the degree of entrainment of CO2-rich corrosive waters from deeper depths. Our MLR-based subsurface (AR) climatology is complementary to surface climatology based on pCO(2) measurements.1184Ysciescopu

BILETA Response to Review of the Computer Misuse Act 1990

© Crown copyright 2023.Given its expertise in Information Technology Law, the British and Irish Law Education Technology Association (BILETA) welcomes the opportunity to contribute to the UK Parliament Science and Technology Committee inquiry about Governance of artificial intelligence (AI). BILETA was formed in April 1986 to promote, develop, and communicate high-quality research and knowledge on technology law and policy to organisations, governments, professionals, students, and the public. BILETA also promotes the use of and research into technology at all stages of education