Development and structure of karstification of the Dong Van Karst Plateau UNESCO Global Geopark, North Vietnam based on cave survey data

This paper presents a quantitative study of the relationship between the cave system and the tectonic and karst evolution of the Dong Van Karst Plateau based on analysis and statistics of geometric parameters and orientation of cave passages. The region is located in northern Vietnam and belongs to the extended part of the South China karst belt (Yunnan karst plateau), which is composed mainly of carbonate rocks. Cave classification based on cave conduits geometric parameters shows that caves developed mainly in the vadose zone (27 vadose branchwork caves, 10 mixed caves developed under the control of fault systems, and 12 water-table caves). The degree of correlation between cave levels and planation surfaces suggests that the development of horizontal cave passages is related to two levels of planation surfaces, including one at 1250–1450 masl (equivalent to cave level at 1350–1450 masl), and at 1000–1250 masl (corresponding to cave level at 1200–1250 masl). Additionally, cave passage orientation shows that the cave system formed and developed under the influence of tectonic activities in the Cenozoic. The dominant orientation trend is roughly in the East–West direction and occurred in the early phase (Eocene–Miocene). Next is a trend roughly North–South that occurred in the late phase (Pliocene–Quaternary). The last orientation trend follows the NW–SE direction due to the reactivation of paleo-fault systems in the same direction. Although there are limitations due to accessibility and the level of cave exploration, this research suggests that analysis and statistics of the geometric parameters and orientation of cave passages based on cave survey data can be one of the effective approaches used to identify the development and structure of karstification in the karst region

Isovector nuclear spin-orbit interaction from chiral pion-nucleon dynamics

Using the two-loop approximation of chiral perturbation theory, we calculate the momentum and density dependent isovector nuclear spin-orbit strength $V_{ls}(p,k_f)$. This quantity is derived from the spin-dependent part of the interaction energy $\Sigma_{spin} = {i\over 2} \vec \sigma \cdot (\vec q \times\vec p)[U_{ls}(p,k_f)- V_{ls}(p,k_f)\tau_3 \delta]$ of a nucleon scattering off weakly inhomogeneous isospin-asymmetric nuclear matter. We find that iterated $1\pi$-exchange generates at saturation density, $k_{f0}=272.7$MeV, an isovector nuclear spin-orbit strength at $p=0$ of $V_{ls}(0,k_{f0}) \simeq 50$ MeVfm$^2$. This value is about 1.4 times the analogous isoscalar nuclear spin-orbit strength $U_{ls}(0,k_{f0})\simeq 35$ MeVfm$^2$ generated by the same two-pion exchange diagrams. We also calculate several relativistic 1/M-corrections to the isoscalar nuclear spin-orbit strength. In particular, we evaluate the contributions from irreducible two-pion exchange to $U_{ls}(p,k_f)$. The effects of the three-body diagrams constructed from the Weinberg-Tomozawa $\pi\pi NN$-contact vertex on the isoscalar nuclear spin-orbit strength are computed. We find that such relativistic 1/M-corrections are less than 20% of the isoscalar nuclear spin-orbit strength generated by iterated one-pion-exchange, in accordance with the expectation from chiral power counting.Comment: 15 pages, 8 figure

Deep desiccation of soils observed by long-term high-resolution measurements on a large inclined lysimeter

Availability of long-term and high-resolution measurements of soil moisture is crucial when it comes to understanding all sorts of changes to past soil moisture variations and the prediction of future dynamics. This is particularly true in a world struggling against climate change and its impacts on ecology and the economy. Feedback mechanisms between soil moisture dynamics and meteorological influences are key factors when it comes to understanding the occurrence of drought events. We used long-term high-resolution measurements of soil moisture on a large inclined lysimeter at a test site near Karlsruhe, Germany. The measurements indicate (i) a seasonal evaporation depth of over 2 m. Statistical analysis and linear regressions indicate (ii) a significant decrease in soil moisture levels over the past 2 decades. This decrease is most pronounced at the start and the end of the vegetation period. Furthermore, Bayesian change-point detection revealed (iii) that this decrease is not uniformly distributed over the complete observation period. The largest changes occur at tipping points during years of extreme drought, with significant changes to the subsequent soil moisture levels. This change affects not only the overall trend in soil moisture, but also the seasonal dynamics. A comparison to modeled data showed (iv) that the occurrence of deep desiccation is not merely dependent on the properties of the soil but is spatially heterogeneous. The study highlights the importance of soil moisture measurements for the understanding of moisture fluxes in the vadose zone.</p

Nuclear spin-orbit interaction from chiral pion-nucleon dynamics

Using the two-loop approximation of chiral perturbation theory, we calculate the momentum and density dependent nuclear spin-orbit strength $U_{ls}(p,k_f)$. This quantity is derived from the spin-dependent part of the interaction energy $\Sigma_{spin} = {i\over 2} \vec \sigma \cdot (\vec q \times\vec p) U_{ls}(p,k_f)$ of a nucleon scattering off weakly inhomogeneous isospin symmetric nuclear matter. We find that iterated $1\pi$-exchange generates at saturation density, $k_{f0}=272.7$MeV, a spin-orbit strength at $p=0$ of $U_{ls}(0,k_{f0})\simeq 35$ MeVfm$^2$ in perfect agreement with the empirical value used in the shell model. This novel spin-orbit strength is neither of relativistic nor of short range origin. The potential $V_{ls}$ underlying the empirical spin-orbit strength $\widetilde U_{ls}= V_{ls} r_{ls}^2$ becomes a rather weak one, $V_{ls}\simeq 17$ MeV, after the identification $r_{ls}= m_\pi^{-1}$ as suggested by the present calculation. We observe however a strong $p$-dependence of $U_{ls}(p,k_{f0})$ leading even to a sign change above $p=200$MeV. This and other features of the emerging spin-orbit Hamiltonian which go beyond the usual shell model parametrization leave questions about the ultimate relevance of the spin-orbit interaction generated by $2\pi$-exchange for a finite nucleus. We also calculate the complex-valued isovector single-particle potential $U_I(p,k_f)+ i W_I(p,k_f)$ in isospin asymmetric nuclear matter proportional to $\tau_3 (N-Z)/(N+Z)$. For the real part we find reasonable agreement with empirical values and the imaginary part vanishes at the Fermi-surface $p=k_f$.Comment: 20 pages, 10 Figures, Accepted for publication in Nuclear Physics

A new insight into the observation of spectroscopic strength reduction in atomic nuclei: implication for the physical meaning of spectroscopic factors

Experimental studies of one nucleon knockout from magic nuclei suggest that their nucleon orbits are not fully occupied. This conflicts a commonly accepted view of the shell closure associated with such nuclei. The conflict can be reconciled if the overlap between initial and final nuclear states in a knockout reaction are calculated by a non-standard method. The method employs an inhomogeneous equation based on correlation-dependent effective nucleon-nucleon (NN) interactions and allows the simplest wave functions, in which all nucleons occupy only the lowest nuclear orbits, to be used. The method also reproduces the recently established relation between reduction of spectroscopic strength, observed in knockout reactions on other nuclei, and nucleon binding energies. The implication of the inhomogeneous equation method for the physical meaning of spectroscopic factors is discussed.Comment: 4 pages, accepted by Phys. Rev. Let

QED Calculation of E1M1 and E1E2 Transition Probabilities in One-Electron Ions with Arbitrary Nuclear Charge

The quantum electrodynamical theory of the two-photon transitions in hydrogenlike ions is presented. The emission probability for 2s1/2 -> 2E1+1s1/2 transitions is calculated and compared to the results of the previous calculations. The emission probabilities 2p12 -> E1E2+1s1/2 and 2p1/2 -> E1M1+1s1/2 are also calculated for the nuclear charge Z values 1-100. This is the first calculation of the two latter probabilities. The results are given in two different gauges.Comment: 14 pages, 4 tables, 1 figur

Regulatory T-cell deficiency leads to features of autoimmune liver disease overlap syndrome in scurfy mice

Scurfy mice have a complete deficiency of functional regulatory T cells (Treg) due to a frameshift mutation in the Foxp3 gene. The impaired immune homeostasis results in a lethal lymphoproliferative disorder affecting multiple organs, including the liver. The autoimmune pathology in scurfy mice is in part accompanied by autoantibodies such as antinuclear antibodies (ANA). ANA are serological hallmarks of several autoimmune disorders including autoimmune liver diseases (AILD). However, the underlying pathogenesis and the role of Treg in AILD remain to be elucidated. The present study therefore aimed to characterize the liver disease in scurfy mice

Regulatory T-cell deficiency leads to features of autoimmune liver disease overlap syndrome in scurfy mice

IntroductionScurfy mice have a complete deficiency of functional regulatory T cells (Treg) due to a frameshift mutation in the Foxp3 gene. The impaired immune homeostasis results in a lethal lymphoproliferative disorder affecting multiple organs, including the liver. The autoimmune pathology in scurfy mice is in part accompanied by autoantibodies such as antinuclear antibodies (ANA). ANA are serological hallmarks of several autoimmune disorders including autoimmune liver diseases (AILD). However, the underlying pathogenesis and the role of Treg in AILD remain to be elucidated. The present study therefore aimed to characterize the liver disease in scurfy mice.MethodsSera from scurfy mice were screened for ANA by indirect immunofluorescence assay (IFA) and tested for a wide range of AILD-associated autoantibodies by enzyme-linked immunosorbent assay, line immunoassay, and addressable laser bead immunoassay. CD4+ T cells of scurfy mice were transferred into T cell-deficient B6/nude mice. Monoclonal autoantibodies from scurfy mice and recipient B6/nude mice were tested for ANA by IFA. Liver tissue of scurfy mice was analyzed by conventional histology. Collagen deposition in scurfy liver was quantified via hepatic hydroxyproline content. Real-time quantitative PCR was used to determine fibrosis-related hepatic gene expression. Hepatic immune cells were differentiated by flow cytometry.ResultsAll scurfy mice produced ANA. AILD-associated autoantibodies, predominantly antimitochondrial antibodies, were detected at significantly higher levels in scurfy sera. CD4+ T cells from scurfy mice were sufficient to induce anti-dsDNA autoantibodies and ANA with an AILD-related nuclear envelope staining pattern. Liver histology revealed portal inflammation with bile duct damage and proliferation, as in primary biliary cholangitis (PBC), and interface hepatitis with portal-parenchymal necroinflammation, as found in autoimmune hepatitis (AIH). In scurfy liver, TNFα and fibrosis-related transcripts including Col1a1, Timp1, Acta2, Mmp2, and Mmp9 were upregulated. The level of proinflammatory monocytic macrophages (Ly-6Chi) was increased, while M2-type macrophages (CD206+) were downregulated compared to wildtype controls. Despite severe hepatic inflammation, fibrosis did not develop within 25 days, which is close to the lifespan of scurfy mice.DiscussionOur findings suggest that Treg-deficient scurfy mice spontaneously develop clinical, serological, and immunopathological characteristics of AILD with overlapping features of PBC and AIH

Constraints on Lorentz violation from clock-comparison experiments

Constraints from clock-comparison experiments on violations of Lorentz and CPT symmetry are investigated in the context of a general Lorentz-violating extension of the standard model. The experimental signals are shown to depend on the atomic and ionic species used as clocks. Certain experiments usually regarded as establishing comparable bounds are in this context sensitive to different types of Lorentz violation. Some considerations relevant to possible future measurements are presented. All these experiments are potentially sensitive to Lorentz-violating physics at the Planck scale.Comment: accepted for publication in Physical Review D; scheduled for issue of December 1, 199