Submersible ground penetrating radar (SGPR) – chances and limits for underwater investigations

Results of submerged ground penetrating radar (SGPR) measurements show spectacular detailed depositional structures of lake floor sediments, which could not be revealed with any other geophysical method yet. Due to its very high resolution, GPR is particularly suitable for archeological prospection on land surfaces and now on lake floors. A case study showed that a submerged archaeological site in Lake Constance (boulder mounds, the so-called “Hügelis”) is interfingering with the sedimentary record. Depositional history reveals that the site must be human-made and dates back to the prehistorical period. 14C ages of sediment and wood poles proved Neolithic age of the more than 170 boulder mounds comprising over 80,000 metric tons of rock

SU(3) Quantum Spin Ladders as a Regularization of the CP(2) Model at Non-Zero Density: From Classical to Quantum Simulation

Quantum simulations would be highly desirable in order to investigate the finite density physics of QCD. $(1+1)$-d $\mathbb{C}P(N-1)$ quantum field theories are toy models that share many important features of QCD: they are asymptotically free, have a non-perturbatively generated massgap, as well as $\theta$-vacua. $SU(N)$ quantum spin ladders provide an unconventional regularization of $\mathbb{C}P(N-1)$ models that is well-suited for quantum simulation with ultracold alkaline-earth atoms in an optical lattice. In order to validate future quantum simulation experiments of $\mathbb{C}P(2)$ models at finite density, here we use quantum Monte Carlo simulations on classical computers to investigate $SU(3)$ quantum spin ladders at non-zero chemical potential. This reveals a rich phase structure, with single- or double-species Bose-Einstein "condensates", with or without ferromagnetic order

Real-time dynamics of open quantum spin systems driven by dissipative processes

We study the real-time evolution of large open quantum spin systems in two spatial dimensions, whose dynamics is entirely driven by a dissipative coupling to the environment. We consider different dissipative processes and investigate the real-time evolution from an ordered phase of the Heisenberg or XY-model towards a disordered phase at late times, disregarding unitary Hamiltonian dynamics. The corresponding Kossakowski-Lindblad equation is solved via an efficient cluster algorithm. We find that the symmetry of the dissipative process determines the time scales which govern the approach towards a new equilibrium phase at late times. Most notably, we find a slow equilibration if the dissipative process conserves any of the magnetization Fourier modes. In these cases, the dynamics can be interpreted as a diffusion process of the conserved quantity.Comment: 28 pages, 11 figures. Revised version: Presentation reorganized and one figure adde

Repatriation Adjustment, Job Satisfaction, and Turnover Intentions as a Function of Core Self-Evaluations and Role Clarity

A growing corpus of employee relocation literature proposes the construct of repatriation work adjustment as not only a desired outcome on behalf of returning employees and their organizations, but also a persistent challenge. Contemporary research consistently traces repatriation work adjustment to a wide range of individual, occupational, and cultural antecedents, while also hypothesizing it as a contributor to desired outcomes. However, there exists a dearth of literature examining the intermediary role of job factors in the relationship between individual differences and repatriation work adjustment. By examining the main and indirect effects of core self-evaluations and role clarity, the present study proposes several hypotheses to determine whether core self-evaluations affect repatriation work adjustment through role clarity, and whether repatriation work adjustment affects job satisfaction and intentions to turnover. To test these mediated models, this study used an online, survey-based design to obtain self-report data from a sample of repatriated employees

Meron- and Semi-Vortex-Clusters as Physical Carriers of Topological Charge and Vorticity

In O($N$) non-linear $\sigma$-models on the lattice, the Wolff cluster algorithm is based on rewriting the functional integral in terms of mutually independent clusters. Through improved estimators, the clusters are directly related to physical observables. In the $(N-1)$-d O($N$) model (with an appropriately constrained action) the clusters carry an integer or half-integer topological charge. Clusters with topological charge $\pm 1/2$ are denoted as merons. Similarly, in the 2-d O(2) model the clusters carry pairs of semi-vortices and semi-anti-vortices (with vorticity $\pm 1/2$) at their boundary. Using improved estimators, meron- and semi-vortex-clusters provide analytic insight into the topological features of the dynamics. We show that the histograms of the cluster-size distributions scale in the continuum limit, with a fractal dimension $D$, which suggests that the clusters are physical objects. We demonstrate this property analytically for merons and non-merons in the 1-d O(2) model (where $D=1$), and numerically for the 2-d O(2), 2-d O(3), and 3-d O(4) model, for which we observe fractal dimensions $D < d$. In the vicinity of a critical point, a scaling law relates $D$ to a combination of critical exponents. In the 2-d O(3) model, meron- and multi-meron-clusters are responsible for a logarithmic ultraviolet divergence of the topological susceptibility.Comment: 14 pages, 5 figures, presented at the 37th International Symposium on Lattice Field Theory - Lattice 2019, 16-22 June 2019, Wuhan, Chin

Paleocurrent direction measurements in a volcanic setting by means of anisotropy of magnetic susceptibility : a case study from the lower Miocene Tepoztlán Formation (Transmexican Volcanic Belt, Central Mexico)

Sources of ancient volcanic rocks are often unknown if they are either eroded and/or covered by younger deposits. This problem, as well as the provenance of reworked volcaniclastic, fluvial and mass-flow deposits, can be partially solved by the application of anisotropy of the magnetic susceptibility (AMS). For massive and poorly sorted volcaniclastic rocks in particular this may be the only way of finding reliable transport directions and therefore allowing for paleogeographic reconstructions. Here, we present a data set of 428 AMS measurements and 249 measurements of sedimentary paleocurrent indicators from the Miocene Tepoztlán Formation at the southern edge of the Transmexican Volcanic Belt (Central Mexico). The highest degree of reliability of AMS measurements is gained for data from lava samples and the lowest from mass flows. Sedimentary structures in sandstones and conglomerates such as trough cross-stratification, asymmetric ripple marks, and the shape of scours and channels could be used to calibrate the results from AMS data and to prove their reliability. AMS data on fluvial deposits point to a drainage systemwith aW–E flow direction, indicating an outflow of the river system into the ancient Gulf of Mexico.Deutsche Forschungsgemeinschaft,project HI 643/5-1.Conacyt (grant 46213)http://www.elsevier.com/locate/sedgeohb201

DX5+NKT cells display phenotypical and functional differences between spleen and liver as well as NK1.1-Balb/c and NK1.1+ C57Bl/6 mice

These results show that DX5+NKT cells are a heterogeneous population, depending on the dedicated organ and mouse strain, that has diverse functional capacity

Increased cytoplasmatic expression of cancer immune surveillance receptor CD1d in anaplastic thyroid carcinomas

Background Anaplastic thyroid carcinomas are associated with rapid tumor growth, short survival time and without any promising therapy to improve the poor prognosis. In this study, expression of immunoregulative receptor CD1d and lymphocyte infiltration in different thyroid tumors as well as in healthy tissue were analyzed in order to find new targets for an immunotherapeutic approach. Methods CD1d immunohistochemistry was performed in samples of 18 anaplastic, 17 follicular, 27 papillary, and 4 medullary thyroid carcinomas as well as in 19 specimens from normal thyroid tissue and additionally in 10 samples of sarcoma, seven malignant melanoma and three spindle-cell lung carcinoma. Furthermore, thyroid samples were stained with antibodies against CD3, CD20, CD56, CD68, and LCA in order to analyze lymphocyte infiltration. Results For the first time CD1d receptor expression on normal thyroid tissue could be demonstrated. Moreover, anaplastic thyroid carcinomas showed significantly higher expression levels compared to other thyroid samples. Most astonishingly, CD1d expression disappeared from the cellular surface and was detected rather in the cytoplasm of anaplastic thyroid carcinoma cells. In addition, histologically similar tumors to anaplastic carcinoma like sarcoma and malignant melanoma revealed distinct CD1d staining patterns. Furthermore, infiltration of T cells, B cells, and macrophages in anaplastic thyroid carcinomas was different when compared to normal thyroid tissue and all other thyroid carcinomas. Conclusions Anaplastic thyroid carcinomas show significantly higher expression of CD1d, a receptor for NKT cells, which are subject of several anticancer therapy studies. These results may offer a novel approach to explore immunotherapeutic treatment options

The role of thickness inhomogeneities in hierarchical cortical folding

For long it has been known that specific patterns of folding are necessary for an optimally functioning brain. For instance, lissencephaly and polymicrogyria can lead to severe mental retardation, short life expectancy, epileptic seizures, and tetraplegia. The construction of a quantitative model on how and why these folds appear is the first step in understanding the cause of these conditions. In recent years, there have been various attempts to understand and model the mechanisms of brain folding. Previous works have shown that mechanical instabilities play a crucial role in the formation of brain folds, and that the geometry of the fetal brain is one of the main factors in dictating the folding characteristics. However, modeling higher-order folding, one of the main characteristics of the human brain, has not been fully tackled. The effects of thickness inhomogeneity in the gyrogenesis of the mammalian brain are studied through finite-element simulations of rectangular slabs. The slabs are divided into two distinct regions, where the outer layer mimics the gray matter, and the inner layer the underlying white matter. Differential growth is introduced by only growing the top layer. The brain tissue is modeled as a neo-Hookean hyperelastic material. Simulations are performed with both, homogeneous and inhomogeneous cortical thickness. The homogeneous cortex is shown to fold into a single wavelength, as common for bilayered materials, while the inhomogeneous cortex folds into more complex conformations: In their early stages of development, structures reminiscent of the deep sulci in the brain are obtained. As the cortex continues to develop, secondary undulations, which are shallower and more variable than the structures obtained in earlier gyrification stage emerge, reproducing well-known characteristics of higher-order folding in the mammalian, and particularly the human, brain.Comment: 13 pages,10 figure