A brief history of long memory: Hurst, Mandelbrot and the road to ARFIMA

Long memory plays an important role in many fields by determining the behaviour and predictability of systems; for instance, climate, hydrology, finance, networks and DNA sequencing. In particular, it is important to test if a process is exhibiting long memory since that impacts the accuracy and confidence with which one may predict future events on the basis of a small amount of historical data. A major force in the development and study of long memory was the late Benoit B. Mandelbrot. Here we discuss the original motivation of the development of long memory and Mandelbrot's influence on this fascinating field. We will also elucidate the sometimes contrasting approaches to long memory in different scientific communitiesComment: 40 page

Abandon Statistical Significance

We discuss problems the null hypothesis significance testing (NHST) paradigm poses for replication and more broadly in the biomedical and social sciences as well as how these problems remain unresolved by proposals involving modified p-value thresholds, confidence intervals, and Bayes factors. We then discuss our own proposal, which is to abandon statistical significance. We recommend dropping the NHST paradigm--and the p-value thresholds intrinsic to it--as the default statistical paradigm for research, publication, and discovery in the biomedical and social sciences. Specifically, we propose that the p-value be demoted from its threshold screening role and instead, treated continuously, be considered along with currently subordinate factors (e.g., related prior evidence, plausibility of mechanism, study design and data quality, real world costs and benefits, novelty of finding, and other factors that vary by research domain) as just one among many pieces of evidence. We have no desire to "ban" p-values or other purely statistical measures. Rather, we believe that such measures should not be thresholded and that, thresholded or not, they should not take priority over the currently subordinate factors. We also argue that it seldom makes sense to calibrate evidence as a function of p-values or other purely statistical measures. We offer recommendations for how our proposal can be implemented in the scientific publication process as well as in statistical decision making more broadly

Bronchial Circulation Angiogenesis in the Rat Quantified with SPECT and Micro-CT

Introduction As pulmonary artery obstruction results in proliferation of the bronchial circulation in a variety of species, we investigated this angiogenic response using single photon emission computed tomography (SPECT) and micro-CT. Materials and methods After surgical ligation of the left pulmonary artery of rats, they were imaged at 10, 20, or 40 days post-ligation. Before imaging, technetium-labeled macroaggregated albumin (99mTc MAA) was injected into the aortic arch (IA) labeling the systemic circulation. SPECT/micro-CT imaging was performed, the image volumes were registered, and activity in the left lung via the bronchial circulation was used as a marker of bronchial blood flow. To calibrate and to verify successful ligation, 99mTc MAA was subsequently injected into the left femoral vein (IV), resulting in accumulation within the pulmonary circulation. The rats were reimaged, and the ratio of the IA to the IV measurements reflected the fraction of cardiac output (CO) to the left lung via the bronchial circulation. Control and sham-operated rats were studied similarly. Results The left lung bronchial circulation of the control group was 2.5% of CO. The sham-operated rats showed no significant difference from the control. However, 20 and 40 days post-ligation, the bronchial circulation blood flow had increased to 7.9 and 13.9%, respectively, of CO. Excised lungs examined after barium filling of the systemic vasculature confirmed neovascularization as evidenced by tortuous vessels arising from the mediastinum and bronchial circulation. Conclusion Thus, we conclude that SPECT/micro-CT imaging is a valuable methodology for monitoring angiogenesis in the lung and, potentially, for evaluating the effects of pro- or anti-angiogenic treatments using a similar approach

New media, familiar dynamics: academic hierarchies influence academics' following behaviour on Twitter

For what reasons do academics follow one another on Twitter? Robert Jäschke, Stephanie B. Linek and Christian P. Hoffmann analysed the Twitter activity of computer scientists and found that while the quality of information provided by a Twitter account is a key motive for following academic colleagues, there is also evidence of a career planning motive. As well as there being reciprocal following between users of the same academic status (except, remarkably, between PhD researchers), a form of strategic politeness can be observed whereby users follow those of higher academic status without necessarily being followed back. The emerging academic public sphere facilitated by Twitter is largely shaped by dynamics and hierarchies all too familiar to researchers struggling to plot their careers in academia

A Morphological Analysis of a Hybrid Swarm of Native \u3ci\u3eUlmus rubra\u3c/i\u3e and Introduced \u3ci\u3eU. pumila\u3c/i\u3e (Ulmaceae) in Southeastern Nebraska

The parental species and hybrid swarm of native Ulmus rubra Muhl. and the introduced, naturalized and weedy U. pumila L. were investigated in a 65-km transect in Lancaster, Saunders, and Butler counties in Nebraska. Thirty-two trees of U. rubra, 32 of U. pumila, and 50 of the hybrid swarm were sampled for leaves and buds and subsampled for flowers and fruits. Leaves were measured for petiole length, blade length, width, primary and secondary teeth per cm, number of secondary teeth per primary tooth, and texture. Buds were scored for color and distribution of trichomes. Flowers were sampled for stamen counts and pollen size. Fruits were measured for length, width, and color and distribution of trichomes. Statistically significant differences (PUlmus × intermedia Elowsky

Predictions of bond percolation thresholds for the kagom\'e and Archimedean (3,122)(3,12^2) lattices

Here we show how the recent exact determination of the bond percolation threshold for the martini lattice can be used to provide approximations to the unsolved kagom\'e and (3,12^2) lattices. We present two different methods, one of which provides an approximation to the inhomogeneous kagom\'e and (3,12^2) bond problems, and the other gives estimates of $p_c$ for the homogeneous kagom\'e (0.5244088...) and (3,12^2) (0.7404212...) problems that respectively agree with numerical results to five and six significant figures.Comment: 4 pages, 5 figure

Ethanol Vapours to Complement or Replace Sulfur Dioxide Fumigation of Table Grapes

Recent studies have shown that dipping table grapes in ethanol solutions at harvest improved storage of the fruit. We report here the first results obtained by treating "Chasselas" table grapes (Vitis vinifera) with ethanol vapours over the storage period. We tested the effect of ethanol at 0, 4 and 8 g/kg fruit during cold storage for 2, 4 and 6 weeks. We measured berry shatter, stem browning, Botrytis rot incidence and sensory appreciation by tasting panels. Ethanol vapours reduced Botrytis rot incidence and berry shatter, but hastened stem browning. Sensory analyses did not detect any differences between treatments

FIFA World Cup 2010 : implications for and effects on the entrepreneurial performance of South Africa’s informal sector

It is well established that so called ‘mega events’ have a marked impact on the socio-economic trajectory of a host nation. Research on the merits of mega- events is fairly substantial, and indeed, derived implications for entrepreneurship in a host country are a recurring theme. Yet, little has been done to investigate the potential impact of these events on the entrepreneurial performance of the informal sector. The informal sector is a significant contributor to employment and to the South African economy and shown to exhibit strong entrepreneurial potential. As such, it provides fertile grounds for research. This paper reflects on the FIFA 2010 world cup as catalyst for entrepreneurial activity in Johannesburg’s informal sector. Associated issues of ambush marketing and perceptions of legalities, formalities, and barriers related to the organisation of the world cup are investigated

Interaktionsprozesse in Führungssituationen – Erfahrungs- und fallbasiertes Lernen an der Universität St.Gallen (HSG)

Auf der Grundlage von Studien zum fallbasierten und erfahrungsbasierten Lernen in der universitären Führungslehre untersucht der Beitrag, inwieweit Bachelor-Studierende Theorien der Führung fallbasiert erlernen können sowie wie die Studierenden diesen Lehransatz beurteilen. Hierfür wird das Konzept eines fallbasierten und erfahrungsbasierten Kurses an der Universität St.Gallen anhand der Lernziele, Lehr- und Prüfungsmethoden vorgestellt. Die qualitative und quantitative studentische Kursevaluation aus sechs Semestern deutet darauf hin, dass die Studierenden den Ansatz positiv bewerteten. Insbesondere lobten sie die eingesetzten Lehrmethoden bei gleichzeitig differenzierten Verbesserungsvorschlägen. Der Beitrag diskutiert die Fragestellungen auch auf einer persönlichen Einschätzung der Autoren