29 research outputs found
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Comprehensive Organic Analysis of Antartic Micrometeorites
Introduction: Micrometeorites (MMs) are thought to be significant contributors of organic material to the early Earth [1], and a variety of techniques have been employed to identify their organic composition [2-6]. These include the identification of key organic groups using combinations of infrared, energy dispersive Xray, electron energy loss and Raman spectroscopy and scanning transmission X-ray microscopy [2-4], highlighting similarities between that of MMs and carbonaceous chondrites.
Few studies, however, have focused on the characterisation of individual micrometeoritic organic components. Microscopic L2MS has been used to identify up to C5 polycyclic aromatic hydrocarbons and their alkyl derivatives [5]. A combination of ionexchange chromatography and fluorimetric detection has also been successful in identifying a number of protein amino acids including glycine and alanine [6].
We have previously reported a method to analyse ?g-sized quantities of extraterrestrial materials, with prior application to assessing organic volatile release from MM atmospheric entry heating simulations [7]. In this study we utilise this technique to characterise the organic composition of Antarctic terrestrial particles and MMs collected in 1994 from Cap-Prudhomme [8]
SCHOOL OF TOMORROW
Tradicionalnoj školi u Srbiji potrebni su radikalni, bolni i sistemski rezovi koji se odnose na njene obrazovne sadržaje (kurikulume), pristupe radu (obrazovnu tehnologiju-metodiku rada) pa i instuticionalno-formalno ustrojstvo (ali i neformalno obrazovanje). U posljednjih 10 godina, pogrešni potezi obrazovnih vlasti su od nastavnika napravili \u27\u27personom non grata\u27\u27, dok su s druge strane, učenicima i roditeljima dana sva moguća prava. Uz to, IKT su u učionicu unijele takve promjene, kojima prosječan nastavnik nije dorastao, a još manje osposobljen, odgovoriti zahtjevima vremena i potrebama novih generacija. Ako i postoje takvi, oni nemaju na raspolaganju kvalitetno oblikovane e-sadržaje. Činjenica da se gotovo dva desetljeća odlagalo uvođenje predmeta Informatike i računala kao obveznog predmeta u osnovne škole u usporedbi sa zemljama čiji predškolci uče osnove programiranja je poražavajuća. Promjene koje se nameću školi sutrašnjice (globalno i lokalno) ići će u svim od navedenih pravaca. Cilj rada je predstavljanje mogućih rješenja za transformiranje današnje škole u školu sutrašnjice.For Traditional school in Serbia are needed radical, painful and system cuts that are related to its educational programs (curricula’s), approaches to the work (educational technology-methodology of work) and even the institutional-formal structure (but and non-formal education). In the last 10 years, the wrong moves from educational authorities made of the teachers \u27\u27persona non grata\u27\u27, while on the other hand, students and parents were given all the possible rights. In addition, ICT made such changes in the classroom, where the average teacher is not up for, and much less qualified, to answer for requirements of the time and the needs of new generations. (\u27\u27Keeping the classical class in such an environment is a nightmare for most of them\u27\u27). Even If there are such, THEY DO NOT OFFER WELL DESIGNED E-CONTENT! The fact that nearly two decades was delayed the introduction of the subject Informatics and computers as a compulsory subject in primary schools in comparison to the countries in which pre-schoolers learn the basics of programming is devastating. Changes imposed at school of tomorrow (global and local) will go to all of the above directions. Serbia will regard to this, \u27\u27as usual catch the last train\u27\u27. The paper aims at presenting possible directions of transformation of today\u27s schools into the schools of tomorrow
Optimizing decomposition of software architecture for local recovery
Cataloged from PDF version of article.The increasing size and complexity of software systems has led to an amplified number of potential failures and as such makes it harder to ensure software reliability. Since it is usually hard to prevent all the failures, fault tolerance techniques have become more important. An essential element of fault tolerance is the recovery from failures. Local recovery is an effective approach whereby only the erroneous parts of the system are recovered while the other parts remain available. For achieving local recovery, the architecture needs to be decomposed into separate units that can be recovered in isolation. Usually, there are many different alternative ways to decompose the system into recoverable units. It appears that each of these decomposition alternatives performs differently with respect to availability and performance metrics. We propose a systematic approach dedicated to optimizing the decomposition of software architecture for local recovery. The approach provides systematic guidelines to depict the design space of the possible decomposition alternatives, to reduce the design space with respect to domain and stakeholder constraints and to balance the feasible alternatives with respect to availability and performance. The approach is supported by an integrated set of tools and illustrated for the open-source MPlayer software
Four‐dimensional‐STEM analysis of the phyllosilicate‐rich matrix of Ryugu samples
Ryugu asteroid grains brought back to the Earth by the Hayabusa2 space mission are pristine samples containing hydrated minerals and organic compounds. Here, we investigate the mineralogy of their phyllosilicate-rich matrix with four-dimensional scanning transmission electron microscopy (4D-STEM). We have identified and mapped the mineral phases at the nanometer scale (serpentine, smectite, pyrrhotite), observed the presence of Ni-bearing pyrrhotite, and identified the serpentine polymorph as lizardite, in agreement with the reported aqueous alteration history of Ryugu. Furthermore, we have mapped the d-spacings of smectite and observed a broad distribution of values, ranging from 1 to 2 nm, with an average d-spacing of 1.24 nm, indicating significant heterogeneity within the sample. Such d-spacing variability could be the result of either the presence of organic matter trapped in the interlayers or the influence of various geochemical conditions at the submicrometer scale, suggestive of a range of organic compounds and/or changes in smectite crystal chemistry
Geomagnetic field declination: from decadal to centennial scales
Declination annual mean time series longer than 1 century provided by 24
geomagnetic observatories worldwide, together with 5 Western European
reconstructed declination series over the last 4 centuries, have been
analyzed in terms of the frequency constituents of the secular variation at
inter-decadal and sub-centennial timescales of 20–35 and
70–90 years. Observatory and reconstructed time series have been processed
by several types of filtering, namely Hodrick–Prescott, running averages, and
Butterworth. The Hodrick–Prescott filtering allows us to separate a
quasi-oscillation at a decadal timescale, which is assumed to be related to external variations and called the 11-year constituent, from a long-term trend. The latter has been decomposed into two other oscillations called
inter-decadal and sub-centennial constituents by applying a
Butterworth filtering with cutoffs at 30 and 73 years, respectively. The
analysis shows that the generally accepted geomagnetic jerks occur around
extrema in the time derivative of the trend and coincide with extrema in the
time derivative of the 11-year constituent. The sub-centennial constituent is
traced back to 1600 in the five 400-year-long time series and seems to be a
major constituent of the secular variation, geomagnetic jerks included
Core surface sub-centennial magnetic flux patches: characteristics and evolution
Abstract Short-term constituents of the secular variation, at inter-decadal (20–30 years) and sub-centennial (60–90 years) time scales, present in observatory data and main field models, are also found in the radial field evolution at core surface. The paper is focused on the sub-centennial constituent in the gufm1 model. Time–Longitude (t–λ) plots, covering the 400 years time span of the model, at various latitudes between 70°N and 70°S, show a clear westward movement of the sub-centennial constituent field features in the 20°N–20°S latitude band. The sub-centennial constituent at latitudes larger than 50°N/S stands in fact for the fine structure of high-latitude flux lobes. Since 1900 this fine structure shows a westward displacement. Time–Latitude (t–φ) plots indicate also northward and southward components of the movement. The traveling speeds of the sub-centennial constituent field are derived, on one hand, empirically based on Time–Longitude and Time–Latitude plots, and on the other, mathematically by means of the Radon transform method. Important results of this paper are related to characterization of the evolution of the radial field at core surface at sub-centennial time scales, namely (1) evidencing two types of azimuthal flow, equatorial and high latitude ones, responsible for the observed westward drift of the surface field, and (2) quantitative information on meridional displacements of the core surface magnetic flux patches