Including nonlocality in exchange-correlation kernel from time-dependent current density functional theory: Application to the stopping power of electron liquids

We develop a scheme for building the scalar exchange-correlation (xc) kernel of time-dependent density functional theory (TDDFT) from the tensorial kernel of time-dependent {\em current} density functional theory (TDCDFT) and the Kohn-Sham current density response function. Resorting to the local approximation to the kernel of TDCDFT results in a nonlocal approximation to the kernel of TDDFT, which is free of the contradictions that plague the standard local density approximation (LDA) to TDDFT. As an application of this general scheme, we calculate the dynamical xc contribution to the stopping power of electron liquids for slow ions to find that our results are in considerably better agreement with experiment than those obtained using TDDFT in the conventional LDA.Comment: 6 pages, 3 figures, accepted to Phys. Rev.

Time-Dependent Density-Functional Theory for the Stopping Power of an Interacting Electron Gas for Slow Ions

Based on the time-dependent density-functional theory, we have derived a rigorous formula for the stopping power of an {\it interacting} electron gas for ions in the limit of low projectile velocities. If dynamical correlation between electrons is not taken into account, this formula recovers the corresponding stopping power of {\it noninteracting} electrons in an effective Kohn-Sham potential. The correlation effect, specifically the excitonic one in electron-hole pair excitations, however, is found to considerably enhance the stopping power for intermediately charged ions, bringing our theory into good agreement with experiment.Comment: 4 pages, 1 figure, Accepted to Phys. Rev. B (Rapid Communication

The Still Bay points of Apollo 11 Rock Shelter, Namibia : an inter-regional perspective

Abstract: Dating to roughly 80,000 to 70,000 years ago, components of the Still Bay technocomplex of southern Africa and their potential behavioural implications have been widely discussed. Stone points with invasive retouch, as defined over 90 years ago by Goodwin and van Riet Lowe, serve as markers for Still Bay assemblages, yet many Still Bay sites remain undated and comprehensive, comparable sets of data for their point assemblages remain unpublished. Much of the Middle Stone Age at the site of Apollo 11 in Namibia was undated until 2010, when a potential Still Bay component was announced. Although a Still Bay assemblage at Apollo 11 would represent the most northwesterly and inland expression of this technocomplex, its points have never been fully analysed. This paper presents their morphometric data and an interpretation of point-production strategies. These results are then compared with data obtained for two South African sites: Hollow Rock Shelter in the Western Cape and Umhlatuzana in KwaZulu-Natal. This comparison demonstrates that whereas there are no statistically significant differences in the morphometric data sets between the three sites, there are both similarities and differences in point-production strategies, cross-section shapes and the use of raw materials for knapping. It is suggested that these similarities and variations represent aspects of how knowledge-transfer systems and knapping conventions were followed on both intra-regional and inter-regional scales

Electronic structure investigation of Ti3AlC2, Ti3SiC2, and Ti3GeC2 by soft-X-ray emission spectroscopy

The electronic structures of epitaxially grown films of Ti3AlC2, Ti3SiC2 and Ti3GeC2 have been investigated by bulk-sensitive soft X-ray emission spectroscopy. The measured high-resolution Ti L, C K, Al L, Si L and Ge M emission spectra are compared with ab initio density-functional theory including core-to-valence dipole matrix elements. A qualitative agreement between experiment and theory is obtained. A weak covalent Ti-Al bond is manifested by a pronounced shoulder in the Ti L-emission of Ti3AlC2. As Al is replaced with Si or Ge, the shoulder disappears. For the buried Al and Si-layers, strongly hybridized spectral shapes are detected in Ti3AlC2 and Ti3SiC2, respectively. As a result of relaxation of the crystal structure and the increased charge-transfer from Ti to C, the Ti-C bonding is strengthened. The differences between the electronic structures are discussed in relation to the bonding in the nanolaminates and the corresponding change of materials properties.Comment: 15 pages, 8 figure

Исследование нанопорошков, синтезированных методом электрического взрыва проводников из сплавов

Исходными данными к работе были данные анализов нанопорошков, полученных методом электрического взрыва проводника в газовых средах и условия их приготовления. Полученные образцы сплава меди и никеля исследовались методами термического анализа, рентгенофазового анализа, электронной микроскопии, распределения частиц по размерам, методом БЭТ и при помощи энергодисперсионного анализа.The initial data for the work were data from analyzes of nanopowders obtained by electric exploding a conductor in gaseous media and the conditions for their preparation. The obtained samples of copper and nickel alloy were investigated by thermal analysis, X-ray phase analysis, electron microscopy, particle size distribution, BET method, and energy-dispersive analysis

Behavioral Modernity and the Cultural Transmission of Structured Information: The Semantic Axelrod Model

Cultural transmission models are coming to the fore in explaining increases in the Paleolithic toolkit richness and diversity. During the later Paleolithic, technologies increase not only in terms of diversity but also in their complexity and interdependence. As Mesoudi and O'Brien (2008) have shown, selection broadly favors social learning of information that is hierarchical and structured, and multiple studies have demonstrated that teaching within a social learning environment can increase fitness. We believe that teaching also provides the scaffolding for transmission of more complex cultural traits. Here, we introduce an extension of the Axelrod (1997} model of cultural differentiation in which traits have prerequisite relationships, and where social learning is dependent upon the ordering of those prerequisites. We examine the resulting structure of cultural repertoires as learning environments range from largely unstructured imitation, to structured teaching of necessary prerequisites, and we find that in combination with individual learning and innovation, high probabilities of teaching prerequisites leads to richer cultural repertoires. Our results point to ways in which we can build more comprehensive explanations of the archaeological record of the Paleolithic as well as other cases of technological change.Comment: 24 pages, 7 figures. Submitted to "Learning Strategies and Cultural Evolution during the Paleolithic", edited by Kenichi Aoki and Alex Mesoudi, and presented at the 79th Annual Meeting of the Society for American Archaeology, Austin TX. Revised 5/14/1

Лабораторна установка для дослідження ступеня очищення і пошкодження коренебульбоплодів

Патент України на корисну модель № 79083, МПК B65G 33/00, 2012.Лабораторна установка для дослідження ступеня очищення і пошкодження коренебульбоплодів, що містить раму, на якій з можливістю кутового та вертикального зміщення на підрамах встановлені секція пруткового транспортера-очисника та секція бітерних очисних валів, завантажувальний бункер, причому під секцією пруткового транспортера-очисника та секцією бітерних очисних валів на рамі розташовані поперечні лотки для відбору від сепарованих домішок, яка відрізняється тим, що кутовий зазор між центральною віссю барабана пруткового транспортера-очисника в зоні вивантаження коренебульбоплодів та центральною віссю першого бітерного очисного вала може змінюватись за рахунок використання різних отворів, які виконані на стійці та підрамі, а осьовий зазор – за рахунок кронштейна з отворами, причому над прутковим транспортером-очисником та секцією бітерних очисних валів встановлені вертикальні та похилі еластичні екрани, а для відбору очищених коренебульбоплодів в зоні вивантаження бітерних очисних валів розташована еластична ємність з можливістю вертикального переміщення та фіксації її задньої частини на вертикальному кронштейні

Can outsiders follow insiders to beat the market? An Event Study on the Stockholm Stock Exchange

i Summary Previous studies have indicated that information asymmetries exist on the financial markets. People with access to non-public information could use that information to their advantage when they trade financial instruments. The Swedish Financial Supervisory Authority (FI) is a public authority that works for stability and efficiency on the financial market. In their work for achieving an efficient market is FI trying to minimize the information asymmetries on the market by keeping a record of all trades being done by what the Swedish law classifies as insiders. The record is public information and a way to inform the market about insider transactions, which creates the question: Can the public information on insider trades kept by FI help an investor to make better investments? Yes, it can! In order to examine the question have we performed event studies on different trading strategies that have been based on information from previous studies in the field. The event studies have focused on insider purchases in Small Cap and Mid Cap companies on the Stockholm Stock Exchange during [2007][2008][2009]. We choose to focus on insider purchases because of its higher relevance for other investors than insider sales. Insiders have several reasons to sell shares in their company, for example portfolio diversification and liquidity needs, but they have one main reason to buy shares, to earn money on their investment. We created and tested three different trading strategies based on the insider purchases executed during 2007-2009. The first trading strategy was based on periods of intensive trading, the second strategy was based on large volume transactions and the third strategy was based on short periods of intensive trading where small purchases were excluded. The first two strategies were applied on Small Cap and Mid Cap separately, while the third strategy was applied on the Small Cap only. We have been using a well-established and highly referenced way to perform our event studies. To be able to test the average development statistically have the returns been aggregated through time and through securities. The trading strategies have been tested over 5, 10, 30 and 90 day periods. The results that we have found indicate that outsiders have a possibility to earn abnormal returns in small companies by using the information provided by FI. The strongest positive result that we attained by our tests was an 1.367% cumulative average abnormal return (CAAR) for a 5 day period with the intensive trading strategy on Small Cap companies. It was surprising that all the tests executed showed negative abnormal return over 30 and 90 days, with some of them being negative statistically significant. The results imply that the trading strategies would not be successful for a time-period over 30 and 90 days. The large volume transaction strategy and the third strategy for Small Cap companies did not result in any statistically significant results but showed positive development for 5 day event periods. We conclude through our study that reported insider trading is valuable for outsiders investing in small companies over short time-periods. The results that we found indicate that smaller companies are less efficiently priced than larger companies. i