Practical Range Minimum Queries Revisited

Finding the position of the minimal element in a subarray A[i..j] of an array A of size n is a fundamental operation in many applications. In 2011, Fischer and Heun presented the first index of size 2n+o(n) bits which answers the operation in constant time for any subarray. The index can be computed in linear time and queries can be answered without consulting the original array. The most recent and currently fastest practical index is due to Ferrada and Navarro (DCC\u2716). It reduces the range minimum query (RMQ) to more fundamental and well studied queries on binary vectors, namely rank and select, and a RMQ query on an array of sublinear size derived from A. A range min-max tree is employed to solve this recursive RMQ call. In this paper, we review their practical design and suggest a series of changes which result in consistently faster query times. Specifically, we provide a customized select implementation, switch to two levels of recursion, and use the sparse table solution for the recursion base case instead of a range min-max tree. We provide an extensive empirical evaluation of our new implementation and also compare it to the state of the art. Our experimental study shows that our proposal significantly outperforms the previous solutions on established benchmarks (up to a factor of three) and furthermore accelerates real world applications such as traversing a succinct tree or listing all distinct elements in an interval of an array

The Quantile Index - Succinct Self-Index for Top-k Document Retrieval

One of the central problems in information retrieval is that of finding the k documents in a large text collection that best match a query given by a user. A recent result of Navarro & Nekrich (SODA 2012) showed that single term and phrase queries of length m can be solved in optimal O(m+k) time using a linear word sized index. While a verbatim implementation of the index would be at least an order of magnitude larger than the original collection, various authors incrementally improved the index to a point where the space requirement is currently within a factor of 1.5 to 2.0 of the text size for standard collections. In this paper, we propose a new time/space trade-off for different top-k indexes. This is achieved by sampling only a quantile of the postings in the original inverted file or suffix array-based index. For those queries that cannot be answered using the sampled version of the index we show how to compute the query results on the fly efficiently. As an example, we apply our method to the top-k framework by Navarro & Nekrich. Under probabilistic assumptions that hold for most standard texts, and for a standard scoring function called term frequency, our index can be represented with only sublinearly many bits plus the space needed for a compressed suffix array of the text, while maintaining poly-logarithmic query times. We evaluate our solution on real-world datasets and compare its practical space usage and performance against state-of-the-art implementations. Our experiments show that our index compresses below the size of the original text. To our knowledge it is the first suffix array-based text index that is able to break this bound in practice even for non-repetitive collections, while still maintaining reasonable query times of under half a millisecond on average for top-10 queries

Inter-kingdom Signaling by the Legionella Quorum Sensing Molecule LAI-1 Modulates Cell Migration through an IQGAP1-Cdc42-ARHGEF9-Dependent Pathway

Small molecule signaling promotes the communication between bacteria as well as between bacteria and eukaryotes. The opportunistic pathogenic bacterium Legionella pneumophila employs LAI-1 (3-hydroxypentadecane-4-one) for bacterial cell-cell communication. LAI-1 is produced and detected by the Lqs (Legionella quorum sensing) system, which regulates a variety of processes including natural competence for DNA uptake and pathogen-host cell interactions. In this study, we analyze the role of LAI-1 in inter-kingdom signaling. L. pneumophila lacking the autoinducer synthase LqsA no longer impeded the migration of infected cells, and the defect was complemented by plasmid-borne lqsA. Synthetic LAI-1 dose-dependently inhibited cell migration, without affecting bacterial uptake or cytotoxicity. The forward migration index but not the velocity of LAI-1-treated cells was reduced, and the cell cytoskeleton appeared destabilized. LAI-1-dependent inhibition of cell migration involved the scaffold protein IQGAP1, the small GTPase Cdc42 as well as the Cdc42-specific guanine nucleotide exchange factor ARHGEF9, but not other modulators of Cdc42, or RhoA, Rac1 or Ran GTPase. Upon treatment with LAI-1, Cdc42 was inactivated and IQGAP1 redistributed to the cell cortex regardless of whether Cdc42 was present or not. Furthermore, LAI-1 reversed the inhibition of cell migration by L. pneumophila, suggesting that the compound and the bacteria antagonistically target host signaling pathway(s). Collectively, the results indicate that the L. pneumophila quorum sensing compound LAI-1 modulates migration of eukaryotic cells through a signaling pathway involving IQGAP1, Cdc42 and ARHGEF9

Manufacturing of W/steel composites using electro-discharge sintering process

Tungsten-steel metal matrix composites are consolidated using electro-discharge sintering. At first steel and tungsten powders are sintered separately and then 25 vol% W, 50 vol% W and 75 vol% W mixed powders are sintered. A thorough process parametric study is carried out involving analysis of the influence of particle size distribution, sintering pressure, and discharge energy on the maximum discharge current and obtained residual porosity. Thermal expansion coefficient and the specific heat capacity of the optimized sintered composites are almost same as their theoretical values, however the thermal conductivities and the mechanical properties are lower than the expected values

A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber

Methods that unambiguously prove microbial plastic degradation and allow for quantification of degradation rates are necessary to constrain the influence of microbial degradation on the marine plastic budget. We developed an assay based on stable isotope tracer techniques to determine microbial plastic mineralization rates in liquid medium on a lab scale. For the experiments, 13C-labeled polyethylene (13C-PE) particles (irradiated with UV-light to mimic exposure of floating plastic to sunlight) were incubated in liquid medium with Rhodococcus ruber as a model organism for proof of principle. The transfer of 13C from 13C-PE into the gaseous and dissolved CO2 pools translated to microbially mediated mineralization rates of up to 1.2 % yr−1 of the added PE. After incubation, we also found highly 13C-enriched membrane fatty acids of R. ruber including compounds involved in cellular stress responses. We demonstrated that isotope tracer techniques are a valuable tool to detect and quantify microbial plastic degradation

Herbstgrundlinien 2012

Die wirtschaftliche Entwicklung in Deutschland wird im zweiten Halbjahr 2012 an Schwung verlieren, im kommenden Jahr wird sie sich aber wieder etwas dynamischer entwickeln. Im Jahresdurchschnitt 2012 wird das reale Bruttoinlandsprodukt das Vorjahresergebnis um 0,9 Prozent übertreffen, im kommenden Jahr steigt es mit 1,6 Prozent. Die Expansion ist in erster Linie durch die binnenwirtschaftliche Dynamik getrieben; die moderate Schwächephase wird den Arbeitsmarkt nur wenig belasten. Die Arbeitslosenquote, die dieses Jahr auf knapp sieben Prozent gesunken ist, wird im Durchschnitt des nächsten Jahres wieder etwas über der Sieben-Prozent-Marke liegen. Dennoch werden die verfügbaren Einkommen deutlich expandieren, wodurch sich schließlich der private Konsum beleben wird. Die Unsicherheiten im Zusammenhang mit der Krise im Euroraum sind zuletzt in Folge des Beschlusses der Europäischen Zentralbank, gegebenenfalls unbegrenzt Staatsanleihen an den Sekundärmärkten aufzukaufen, etwas zurückgegangen. Für die konjunkturelle Entwicklung in der Währungsunion wirkt dies stützend. Vor allem die Wirtschaft in den Krisenländern, aber auch im Euroraum als Ganzem, dürfte im kommenden Jahr trotzdem nur wenig wachsen. Auch global bleibt die konjunkturelle Dynamik zunächst gedämpft. Die in vielen fortgeschrittenen Volkswirtschaften anhaltend hohe Arbeitslosigkeit sowie die Verschuldung der privaten und öffentlichen Haushalte belasten die wirtschaftliche Entwicklung. Die Schwellenländer bleiben deutlich hinter dem dynamischen Wachstum in den Vorjahren zurück. Allerdings dürfte dank anhaltend expansiv ausgerichteter Geld- und Finanzpolitik die Konjunktur zunächst in den Schwellenländern, im weiteren Verlauf dann auch in den fortgeschrittenen Volkswirtschaften wieder etwas an Tempo gewinnen. Auf die deutsche Konjunktur wirkt das schwächere weltwirtschaftliche Umfeld zunächst dämpfend; ab dem kommenden Jahr sind aber wieder etwas kräftigere Impulse für den Außenhandel zu erwarten. Die Löhne dürften sowohl in diesem als auch im nächsten Jahr merklich zulegen. Trotz zuletzt wieder anziehender Energiepreise wird die Inflationsrate im Prognosezeitraum wohl nahe der Zwei-Prozent-Marke bleiben. So ergeben sich trotz der zwischenzeitlich rückläufigen Beschäftigung merkliche Kaufkraftgewinne bei den Haushalten, die den privaten Konsum spürbar expandieren lassen dürften. Ab dem Jahreswechsel dürften auch die Investitionen wieder zulegen; im Umfeld der nachlassenden Unsicherheit in Zusammenhang mit der Finanzkrise, aber auch der sich weiter verbessernden Absatzmöglichkeiten, kommen die für Deutschland extrem günstigen Finanzierungsbedingungen wieder stärker zum Tragen. Der Außenhandel leistet dabei durchgehend einen positiven, aber recht geringen Wachstumsbeitrag, da die Exporte aufgrund der schwächeren Entwicklung der Weltkonjunktur an Schwung verlieren und die kräftigere Binnenwirtschaft den Import stärker anzieht. Auch in der mittleren Frist dürfte die wirtschaftliche Entwicklung in Deutschland von günstigen Finanzierungsbedingungen, Lohnzuwächsen und einer dynamischen Binnennachfrage geprägt sein. Der deutsche Leistungsbilanzüberschuss dürfte in den fünf Jahren des mittelfristigen Prognosezeitraums relativ zum Bruttoinlandsprodukt deutlich zurückgehen. Der öffentliche Gesamthaushalt wird 2012 und 2013 mit Überschüssen abschließen; in Relation zum nominalen Bruttoinlandsprodukt dürften sie in beiden Jahren bei 0,3 Prozent liegen. Dies resultiert vor allem aus der guten Entwicklung der staatlichen Einnahmen, aber auch auf der Ausgabenseite zeigt sich eine relativ geringe Dynamik. Der Bundeshaushalt ist allerdings noch deutlich unterfinanziert. Da im Zusammenhang mit der Finanzkrise noch erhebliche Risiken auf den Bund zukommen können, ist dies bedenklich. Der Konsolidierungsprozess ist daher noch nicht vollständig abgeschlossen.The German economy will lose some of its momentum in the second half of the year, but pick up some speed again next year. In year-on-year terms, German GDP is expected to increase by a mere 0.9 percent in 2012 and 1.6 percent in 2013. Growth is primarily driven by domestic demand. The weakening of the economy in the second half of this year will have limited impact on labor markets, the unemployment rate will only increase slightly from 6.8 percent in 2012 to 7.1 percent in 2013. Hence, disposable income will grow at solid rates and support consumption of private households. Uncertainties surrounding the crisis in the euro area have slightly decreased after the ECB's announcement to expand its stabilization activities on government bond markets. This should support economic developments in the euro area. However, growth will remain weak in the crisis countries in particular and in the euro area as a whole. In addition, global economic dynamics are weak. Persistently high rates of unemployment and high levels of sovereign and private debt continue to hamper economic development in many advanced economies. Growth in emerging economies will slow down compared to the high rates seen in previous years. However, monetary and fiscal policy remain expansionary there. This should stimulate growth first in emerging economies and subsequently in advanced economies. Weakening global demand is a drag on growth in Germany in the second half of this year; as of next year, an acceleration of the economic development is expected. Wages will increase substantially both this year and next year; inflation will remain close to two per cent. Consequently, the purchasing power of households is increasing, allowing private consumption to be a major driver of growth. Investment will increasingly contribute to growth in the course of next year; with decreasing uncertainties due to financial crisis as well as improving demand prospects, the extremely favorable financing conditions will gain in importance for investors. Compared to domestic demand, foreign trade is expected to have a moderate influence on economic growth, since exports are losing momentum due to a weak global economy and imports are increasing due to solid domestic demand. Over the medium term, economic developments in Germany will continue to be shaped by favorable financing conditions, solid wage developments, and strong domestic demand; the German current account surplus relative to GDP is projected to decline substantially over the five-year horizon. The general government's budget is expected to show a surplus of 0.3 percent of nominal GDP in both years. Revenues are boosting public finances, while public spending will only increase slightly. While the general government's financial position is improving, the German federal government is persistently facing high deficits. This is much more alarming as there are still substantial financial risks most notably those related to the crisis in the euro area. Therefore, the fiscal consolidation process in Germany is not yet completed

Algorithmic Complexity for Short Binary Strings Applied to Psychology: A Primer

Since human randomness production has been studied and widely used to assess executive functions (especially inhibition), many measures have been suggested to assess the degree to which a sequence is random-like. However, each of them focuses on one feature of randomness, leading authors to have to use multiple measures. Here we describe and advocate for the use of the accepted universal measure for randomness based on algorithmic complexity, by means of a novel previously presented technique using the the definition of algorithmic probability. A re-analysis of the classical Radio Zenith data in the light of the proposed measure and methodology is provided as a study case of an application.Comment: To appear in Behavior Research Method