Self-oscillations in field emission nanowire mechanical resonators: a nanometric DC-AC conversion

We report the observation of self-oscillations in a bottom-up nanoelectromechanical system (NEMS) during field emission driven by a constant applied voltage. An electromechanical model is explored that explains the phenomenon and that can be directly used to develop integrated devices. In this first study we have already achieved ~50% DC/AC (direct to alternative current) conversion. Electrical self-oscillations in NEMS open up a new path for the development of high speed, autonomous nanoresonators, and signal generators and show that field emission (FE) is a powerful tool for building new nano-components

Научные подходы к диагностике социо-эколого-экономической устойчивости приморских регионов

На основе научных подходов предложена методика, позволяющая опреде-лить уровень социо-эколого-экономической устойчивости приморских ре-гионов. На основе использования системы показателей, характеризующих уровень социо-эколого-экономической устойчивости региона, сформули-рованы и предложены основные направления реализации методики опре-деления интегрального показателя уровня устойчивости приморской территории в социальном, экономическом и экологическом развитии.Based on the scientific approaches proposed technique allows to deter-mine the level of social, ecological and economic sustainability of coastal re-gions. On the basis of a system of indicators characterizing the level of social, ecological and economic sustainability of the region, formulate and propose guidelines implementation methodology for determining the integral indicator of the sustainability of the coastal territory in the social, economic and envi-ronmental development

Петрологічні дослідження в Україні: досягнення останніх десятиліть та нагальні проблеми

Викладено основні досягнення за останні 30–35 років українських геологів, в першу чергу — наукових працівників ІГМР ім. М. П. Семененка НАН України в області петрології. Висвітлені такі проблеми: 1 — метаморфізм, співвідношення грануліто-гнейсових і граніт-зеленокам’яних терейнів; 2 — чарнокіти; 3 — гранітоутворення та гранітоїдні формації; 4 — анортозит-рапаківігранітна формація; 5 — лужні породи; 6 — коматиїти; 7 — санукітоїди; 8 — метасоматоз; 9 — породоутворювальні та акцесорні мінерали; 10 — формаційний аналіз, петрологія та стратиграфія докембрію; 11 — фанерозойський магматизм; 12 — магматизм морського та океанічного дна; 13 — деякі нагальні проблеми.Изложены основные достижения за последние 30–35 лет украинских геологов, в первую очередь — научных сотрудников ИГМР им. Н. П. Семененко НАН Украины в области петрологии. Освещены такие проблемы: 1 — метаморфизм, соотношение гранулито-гнейсовых и гранит-зеленокаменных террейнов; 2 — чарнокиты; 3 — гранитообразование и гранитоидные формации; 4 — анортозит-рапакивигранитная формация; 5 — щелочные породы; 6 — коматииты; 7 — санукитоиды; 8 — метасоматоз; 9 — породообразующие и акцессорные минералы; 10 — формационный анализ, петрология и стратиграфия докембрия; 11 — фанерозойский магматизм; 12 — магматизм морского и океанического дна; 13 — некоторые насущные проблемы.Main achievements of Ukrainian geologists for the recent 30–35 years have been stated. In the first place the scientific results of petrologists of M. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of NAS of Ukraine. The following problems have been elucidated: 1 — metamorphism; interrelation of granulite-gneissic and granite-greenstone terrains; 2 — charnokites; 3 — granite formation and granitoid formations; 4 — anorthosite-rapakivi-granite formation; 5 — alkaline rocks; 6 — komatiites; 7 — sanukitoids; 8 — metasomatosis; 9 — rock-forming and accessory minerals; 10 — formation analysis, petrology and Precambrian stratigraphy; 11 — Phanerozoic magmatism; 12 — magmatism of the sea and ocean bottom; 13 — some current problems

Postural control and cognitive decline in older adults: Position versus velocity implicit motor strategy

The present study explored the impact of cognitive decline on postural control strategies in older adults with and without cognitive decline from mild cognitive impairment (MCI) to mild-to-moderate Alzheimer disease (MMAD). We hypothesized that the cognitive decline affected the postural control leading to higher bounding limits of COP velocity dynamics. Based on a cross-sectional design, 175 non-faller older adults were recruited in Angers University Hospital, France, including 50 cognitively healthy individuals [CHI] (mean age 76.42 +/- 4.84 years; 30% women), 64 age-and body mass index-matched participants with MCI (mean age 77.51 +/- 6.32 years; 39% women), and 61 age- and body mass index-matched participants with MMAD (mean age 78.44 +/- 3.97 years; 62% women). For all data collection of postural sway, the participants were asked to maintain quiet stance on force platform. The postural test consisted of two trials of quiet stance, with eyes open and with eyes closed. The COP parameters were mean and standard deviation (SD) of position, velocity and average absolute maximal velocity (AAMV) in anteroposterior and medio-lateral directions. Overall, the analysis concerning all COP parameters revealed a significant main effect of cognitive status on velocity-based variables, with post hoc comparisons evidencing that SD velocity and AAMV increased with cognitive impairment. The current findings suggest an active control (or corrective process) of COP velocity dynamics for CHI, whereas MCI and MMAD are affected by COP movements. (C) 2013 Elsevier B.V. All rights reserved

Statistical properties of charged interfaces

We consider the equilibrium statistical properties of interfaces submitted to competing interactions; a long-range repulsive Coulomb interaction inherent to the charged interface and a short-range, anisotropic, attractive one due to either elasticity or confinement. We focus on one-dimensional interfaces such as strings. Model systems considered for applications are mainly aggregates of solitons in polyacetylene and other charge density wave systems, domain lines in uniaxial ferroelectrics and the stripe phase of oxides. At zero temperature, we find a shape instability which lead, via phase transitions, to tilted phases. Depending on the regime, elastic or confinement, the order of the zero-temperature transition changes. Thermal fluctuations lead to a pure Coulomb roughening of the string, in addition to the usual one, and to the presence of angular kinks. We suggest that such instabilities might explain the tilting of stripes in cuprate oxides. The 3D problem of the charged wall is also analyzed. The latter experiences instabilities towards various tilted phases separated by a tricritical point in the elastic regime. In the confinement regime, the increase of dimensionality favors either the melting of the wall into a Wigner crystal of its constituent charges or a strongly inclined wall which might have been observed in nickelate oxides.Comment: 17 pages, 11 figure

A multipurpose machine to study paramagnetic species on well defined single crystal surfaces

A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic species with a density of approximately 5 × 1011 spins/cm2, which is comparable to the limit obtained for the presently available UHV-EPR spectrometer operating at 10 GHz (X-band). Investigation of electron trapped centers in MgO(001) films shows that the increased resolution offered by the experiments at W-band allows to identify new paramagnetic species, that cannot be differentiated with the currently available methodology

Casper: Debugging Null Dereferences with Dynamic Causality Traces

Fixing a software error requires understanding its root cause. In this paper, we introduce "causality traces", crafted execution traces augmented with the information needed to reconstruct the causal chain from the root cause of a bug to an execution error. We propose an approach and a tool, called Casper, for dynamically constructing causality traces for null dereference errors. The core idea of Casper is to inject special values, called "ghosts", into the execution stream to construct the causality trace at runtime. We evaluate our contribution by providing and assessing the causality traces of 14 real null dereference bugs collected over six large, popular open-source projects. Over this data set, Casper builds a causality trace in less than 5 seconds

Quantitative evaluation of chromosomal rearrangements in gene-edited human stem cells by CAST-Seq

Genome editing has shown great promise for clinical translation but also revealed the risk of genotoxicity caused by off-target effects of programmable nucleases. Here we describe chromosomal aberrations analysis by single targeted linker-mediated PCR sequencing (CAST-Seq), a preclinical assay to identify and quantify chromosomal aberrations derived from on-target and off-target activities of CRISPR-Cas nucleases or transcriptional activator-like effector nucleases (TALENs), respectively, in human hematopoietic stem cells (HSCs). Depending on the employed designer nuclease, CAST-Seq detected translocations in 0%–0.5% of gene-edited human CD34+ HSCs, and up to 20% of on-target loci harbored gross rearrangements. Moreover, CAST-Seq detected distinct types of chromosomal aberrations, such as homology-mediated translocations, that are mediated by homologous recombination and not off-target activity. CAST-Seq is a sensitive assay able to identify and quantify unintended chromosomal rearrangements in addition to the more typical mutations at off-target sites. CAST-Seq analyses may be particularly relevant for therapeutic genome editing to enable thorough risk assessment before clinical application of gene-edited products

Analysis of path integrals at low temperature : Box formula, occupation time and ergodic approximation

We study the low temperature behaviour of path integrals for a simple one-dimensional model. Starting from the Feynman-Kac formula, we derive a new functional representation of the density matrix at finite temperature, in terms of the occupation times of Brownian motions constrained to stay within boxes with finite sizes. From that representation, we infer a kind of ergodic approximation, which only involves double ordinary integrals. As shown by its applications to different confining potentials, the ergodic approximation turns out to be quite efficient, especially in the low-temperature regime where other usual approximations fail