Effects of Impurities and their Redistribution during Recrystallization of Ice Crystals

In order to examine the effects of solutes on recrystallization and subsequent grain growth in ice, both doped and undoped ice single crystals were extruded through a 120o equal-channel angular extrusion jig, in order to impart a large shear strain (~1.15). Upon subsequent annealing at –3o C, the original single crystals recrystallized, in most cases to a new single crystal with a different orientation. Increasing the solute concentration (for H2SO4 to ~200–300ppb, and for NaCl, KCl and MgSO4 to \u3e5ppm) was found to significantly retard the growth and possibly, for H2SO4-doped ice, the nucleation of new grains in the strained ice single crystals. This is indicative of how soluble impurities can retard grain growth in ice cores. It was also found that the migrating grain boundaries surrounding the newly formed grains contained large concentrations of impurities, often observed as filaments. These could have formed by the grain boundaries sweeping up impurities from the lattice into the boundary or by their diffusion to the boundary–mechanisms whereby impurities could be concentrated into the grain boundaries in ice cores– although the latter mechanism seems unlikely since it would require very high diffusion rates

Lagrangian Data-Driven Reduced Order Modeling of Finite Time Lyapunov Exponents

There are two main strategies for improving the projection-based reduced order model (ROM) accuracy: (i) improving the ROM, i.e., adding new terms to the standard ROM; and (ii) improving the ROM basis, i.e., constructing ROM bases that yield more accurate ROMs. In this paper, we use the latter. We propose new Lagrangian inner products that we use together with Eulerian and Lagrangian data to construct new Lagrangian ROMs. We show that the new Lagrangian ROMs are orders of magnitude more accurate than the standard Eulerian ROMs, i.e., ROMs that use standard Eulerian inner product and data to construct the ROM basis. Specifically, for the quasi-geostrophic equations, we show that the new Lagrangian ROMs are more accurate than the standard Eulerian ROMs in approximating not only Lagrangian fields (e.g., the finite time Lyapunov exponent (FTLE)), but also Eulerian fields (e.g., the streamfunction). We emphasize that the new Lagrangian ROMs do not employ any closure modeling to model the effect of discarded modes (which is standard procedure for low-dimensional ROMs of complex nonlinear systems). Thus, the dramatic increase in the new Lagrangian ROMs' accuracy is entirely due to the novel Lagrangian inner products used to build the Lagrangian ROM basis

Brittle Compressive Failure of Ice: Proportional Straining vs Proportional Loading

Proportional straining experiments have been performed on columnar-grained S2 fresh- water ice biaxially compressed across the columns at –108C at a strain rate of (4.5 1.5) 10–3 s–1. The results are compared with those obtained earlier (Iliescu and Schulson, 2004) from the same kind of material deformed to terminal failure under the same conditions, but through proportional loading. The exercise shows that the biaxial strength is practically independent of the path taken, at least under low confinement where Coulombic shear faulting limits terminal failure. First-year sea ice is expected to exhibit the same behavior

Characterisation of Epstein-Barr virus-specific memory T cells from the peripheral blood of seropositive individuals.

We have investigated the regression phenomenon which occurs when EBV-infected peripheral blood mononuclear cells from seropositive individuals are cultured for one month at high cell concentration and have confirmed that regression is mediated by E+ lymphocytes. When helper/inducer (Leu 3a+) and suppressor/cytotoxic (Leu 2a+) cells are separated by fluorescence-activated cell sorting from fresh peripheral blood and co-cultured with EBV-infected autologous E- mononuclear cells, regression only regularly occurs in cultures receiving suppressor/cytotoxic lymphocytes. Titration experiments show that suppressor/cytotoxic lymphocytes are more active in the regression assay that unfractionated E+ cells. When Ia+ E+ and Ia- E+ cells are separated one week after initiation of co-cultures of E+ cells and EBV-infected E- cells, both Ia+ E+ and Ia- E+ cells are active in the regression assay although regression occurs earlier in cultures receiving Ia+ E+ cells. Experiments in which NK cells are isolated using the monoclonal antibodies H25 and H366 show that NK cells do not influence the regression phenomenon in normal individuals

Our policy in intraventricular colloid cysts. Experience of 31 operated cases.

The colloid cyst of the third ventricle is abenign tumor situated in the anterior partof the third ventricle. This lesion representsless than 1% of the primary brain tumorbeing more common in young adults.Because of its particular location, thecolloid cyst can obstruct the Monroforamen, producing intermittentintracranian hypertension with headache,vomiting and visual disturbances. Thirtyonecases of colloid cysts have beenoperated using the microsurgical approachin the First Neurosurgical Department ofEmergency Clinical Hospital “Bagdasar-Arseni” between January 1995 andDecember 2008. The age of the patientswas between 17 and 46 years, with amedium age of 31 years. The follow-upperiod was between 9 months and 7 years.In three cases TTA approach has beenperformed. One of the cases developed avenous cerebral infarct after this procedure,but the patient had finally a good outcome.For 28 patients the transcortical approachhas been performed. In all cases the totalresection of the colloid cyst has beenperformed. Of all 31 cases, one casepresented a transitory hemiparesis, twocases showed negativist behavior, and threecases had transitory memory disturbances.There was no intraventricular hemorrhageafter colloid cyst resection in our series. Inconclusion, according to our policy, themicrosurgical approach is the besttreatment for third ventricular colloid cystsbecause of its main advantages comparedwith the endoscopic approach: thepossibility of total resection of the cyst, thegood control of the bleeding source duringthe procedure, and a better exposure of theanatomical landmarks

Steady-state response feature extraction optimization to enhance electronic nose performance

Feature extraction of electronic nose (e-nose) output response aims to reduce information redundancy so that the e-nose performance can be improved. The use of different sensor types and sample targets can affect the optimization of feature extraction. This research used six types of metal oxide sensors, TGS 813, 822, 825, 826, 2620, and 2611 in an e-nose system to detect three types of herbal drink. Five kinds of feature extraction methods on the original response curve in a steady-state response were used, namely, baseline difference, logarithmic difference, local normalization, global normalization, and global autoscaling. The results of feature extraction were fed into a Principal Component Analysis (PCA) system. As a result, global autoscaling and normalization had the highest total sum of the first and second principal components of 96.96%, followed by local normalization (90.18%), logarithm, and baseline difference (88.92% and 79.26%, respectively). The validation of PCA results was performed using a Backpropagation Neural Network (BPNN). The highest accuracy, 97.44%, was obtained from the global autoscaling method, followed by global normalization, local normalization, logarithm, and baseline difference, with an accuracy level of 94.87%, 92.31%, 89.74%, and 82.05%, respectively. This demonstrates that the selection of the feature extraction method can affect the classification results and improve e-nose performance

The walking robots critical position of the kinematics or dynamic systems applied on the environment model

© 2018 Authors. The exposure is dedicated in the first to mathematical modeling of the environment where the aspects on the walking robots evolution models are described. The environment's mathematical model is defined through the models of kinematics or dynamic systems in the general case of systems that depend on parameters. The important property of the dynamic system evolution models that approach the phenomenon from the environment is property of separation between stable and unstable regions from the free parameters domain of the system. Some mathematical conditions that imply the separation of stable regions from the free parameters domain of the system are formulated. In the second part is described our idea on walking robot kinematics and dynamic models with aspects exemplified on walking robot leg. An inverse method for identification of possible critical positions of the walking robot leg is established

VIP: An Experiment to Search for a Violation of the Pauli Exclusion Principle

The Pauli Exclusion Principle is a basic principle of Quantum Mechanics, and its validity has never been seriously challenged. However, given its fundamental standing, it is very important to check it as thoroughly as possible. Here we describe the VIP (VIolation of the Pauli exclusion principle) experiment, an improved version of the Ramberg and Snow experiment (E. Ramberg and G. Snow, {\it Phys. Lett. B} {\bf 238}, 438 (1990)); VIP has just completed the installation at the Gran Sasso underground laboratory, and aims to test the Pauli Exclusion Principle for electrons with unprecedented accuracy, down to $\beta^2/2 \approx 10^{-30} - 10^{-31}$. We report preliminary experimental results and briefly discuss some of the implications of a possible violation.Comment: Plenary talk presented by E. Milotti at Meson 2006, Cracow, 9-13 June 200

New experimental limit on the Pauli Exclusion Principle violation by electrons

The Pauli Exclusion Principle (PEP) is one of the basic principles of modern physics and, even if there are no compelling reasons to doubt its validity, it is still debated today because an intuitive, elementary explanation is still missing, and because of its unique stand among the basic symmetries of physics. The present paper reports a new limit on the probability that PEP is violated by electrons, in a search for a shifted K$_\alpha$ line in copper: the presence of this line in the soft X-ray copper fluorescence would signal a transition to a ground state already occupied by 2 electrons. The obtained value, ${1/2} \beta^{2} \leq 4.5\times 10^{-28}$, improves the existing limit by almost two orders of magnitude.Comment: submitted to Phys. Lett.