Setting the stage for data science: integration of data management skills in introductory and second courses in statistics

Many have argued that statistics students need additional facility to express statistical computations. By introducing students to commonplace tools for data management, visualization, and reproducible analysis in data science and applying these to real-world scenarios, we prepare them to think statistically. In an era of increasingly big data, it is imperative that students develop data-related capacities, beginning with the introductory course. We believe that the integration of these precursors to data science into our curricula-early and often-will help statisticians be part of the dialogue regarding "Big Data" and "Big Questions"

Social Identity and Psychosis: Associations and Psychological Mechanisms

Humans possess a basic need to belong and will join groups even when they provide no practical benefit. Paranoid symptoms imply a disruption of the processes involved in belonging and social trust. Past research suggests that joining social groups and incorporating those groups into one’s identity (social identification) promotes positive self-views and better physical and mental health. However, no research has investigated whether social identity is associated with paranoia, nor the mechanisms by which this effect may emerge. Here, we examined the relationship between social identity and mental health (paranoia, auditory verbal hallucinations [AVHs], and depression), and tested the mediating role of self-esteem. In study 1, we analyzed data collected from 4319 UK residents as part of the NIHR CLAHRC NWC Household Health Survey. Study 2 comprised data collected from 1167 students attending a large UK university. The studies provided convergent evidence that social identification reduces symptoms of paranoia and depression by furnishing people with self-esteem. There was no consistent effect of social identification on AVHs. People developing mental health assessments, treatments, and policies are encouraged to consider the notion that joining and identifying with social groups may reduce people’s risk of paranoia and depression

The Microstratigraphy of Two Peat Sequences from Northeastern Newfounland

Commonly, the ombrotrophic peats of Newfoundland have a well-defined banded appearance. Each band consists of a light-coloured lower section and a dark upper component. The bands are separated by abrupt recurrence surfaces. The regularity of the bands implies cyclicity. The physical, elemental, micro- and macro-stratigraphies of two banded profiles from the Wesleyville area were examined in an attempt to document the differences and to provide insight into cause. Ash content, fibre content, bulk density, water content and water retention were measured. The latter three showed consistent changes through each profile. There were no obvious patterns in the values for the biologically active elements that were measured (Mg, Cl, Ca, Na, Al, Mn and I), but the curves for Br, V, and U, biologically inert elements, showed systematic variations that appear to reflect variations in peat accumulation rate. The pollen, spore and macrofossil stratigraphies were generally complacent, although the representation of Sphagnum macrofossils and spores varied regularly as did pollen and spore concentrations. Each light-dark sequence appears to reflect a cycle of self-sustaining hydrologie changes involving changes in community composition, and in oxidation and accumulation rate, rather than climate. The cycles appear to be ca. 700 years in length, and are system-wide, but with variable lag times.Les tourbes ombrothrophes de Terre-Neuve présentent d'ordinaire des couches nettement définies. Chaque couche comporte une partie inférieure claire et une partie supérieure foncée. Les couches sont séparées par des surfaces de récurrence abruptes. La régularité des couches suppose l'existence d'un phénomène cyclique. Les micro et macrostratigraphies physique et celles des éléments de deux coupes de deux profils rubanés de la région de Wesleyville ont été étudiés en vue d'en observer les différences et de déterminer les causes de ces différences. Les teneurs en cendres et en fibres, le poids volumétrique, la teneur en eau et la rétention d'eau ont été mesurés. Les trois dernières propriétés ont montré des changements uniformes dans chacune des coupes. Aucune configuration évidente n'est ressortie des valeurs des éléments biologiquement actifs qui ont été mesurés (Mg, Cl, Ca, Na, Mn et I), mais les courbes de Br, V et U, biologiquement inertes, ont montré des variations systématiques qui semblaient refléter les variations du taux d'accumulation de la tourbe. Les stratigraphies du pollen, des spores et des macrofossiles étaient dans l'ensemble insensibles, bien que la représentation des macrofossiles et des spores de Sphagnum variait de façon régulière, tout comme les concentrations de pollen et de spores. Chacune des séquences claire-foncée semble correspondre à un cycle de changements hydrologiques autogénérateurs impliquant des modifications dans la composition de l'association végétale et dans les taux d'oxydation et d'accumulation, plutôt que dans le climat. Les cycles, qui s'étendent à l'ensemble du système, semblent durer environ 700 ans, mais avec des décalages variables.Im allgemeinen treten die ombrotrophen Torfe Neufundlands in gut erkennbaren Streifen auf. Jeder Streifen besteht aus einer leichtgefàrbten unteren Schicht und einem dunklen oberen Teil. Die Streifen werden durch plôtzlich zu Tage tretende Grenzhorizonte getrennt. Die RegelmâBigkeit der Streifen setzt Periodizitàt voraus. Die Milkro- und Makrostratigraphie des physikalischen und elementaren Aufbaus zweier Streifenprofile aus der Gegend von Wesleyville wurden untersucht, um die Unterschiede aufzuzeichnen und um die Ursachen zu ergrùnden. Gehalt an Asche und Fasern, spezifische Dichte, Wassergehalt und Wasserzurùckhaltungsvermôgen wurden gemessen. Die drei letzteren wiesen konstante Wechsel in jedem Profil auf. Keine deutlichen Muster in den Werten der biologisch aktiven Elemente konnten gemessen werden (Mg, Cl, Ca, Na, Al, Mn und I), aber die kurven von Br, V und U, den biologisch inaktiven Elementen, zeigten systematische Variationen, welche die Variationen von Torfansammlungsraten wiederzuspiegeln schienen. Die Pollen-, Sporen- und makrofossilen Stratigraphien waren im allgemeinen unveràndert, wenn auch das Vorkommen von Sphagnum-Makrofossilen und Sporen genauso wie Pollen- und Sporen- konzentrationen regelmâBige Verànderungen aufwies. Jede helldunkel Sequenz scheint einen Zyklus sich selbsttragender hydrologischer Verâderungen wiederzuspiegeln, die viel mehr Verànderungen in der pflanzlichen Zusammensetzung, der Oxydierung und der Akkumulationsrate zur Folge hatten als klimatische Verànderungen. Die Perioden scheinen etwa 700 Jahre gedauert zu haben, betreffen das ganze System aber mit variablen Verzôgerungen

The Effect of the LISA Response Function on Observations of Monochromatic Sources

The Laser Interferometer Space Antenna (LISA) is expected to provide the largest observational sample of binary systems of faint sub-solar mass compact objects, in particular white-dwarfs, whose radiation is monochromatic over most of the LISA observational window. Current astrophysical estimates suggest that the instrument will be able to resolve about 10000 such systems, with a large fraction of them at frequencies above 3 mHz, where the wavelength of gravitational waves becomes comparable to or shorter than the LISA arm-length. This affects the structure of the so-called LISA transfer function which cannot be treated as constant in this frequency range: it introduces characteristic phase and amplitude modulations that depend on the source location in the sky and the emission frequency. Here we investigate the effect of the LISA transfer function on detection and parameter estimation for monochromatic sources. For signal detection we show that filters constructed by approximating the transfer function as a constant (long wavelength approximation) introduce a negligible loss of signal-to-noise ratio -- the fitting factor always exceeds 0.97 -- for f below 10mHz, therefore in a frequency range where one would actually expect the approximation to fail. For parameter estimation, we conclude that in the range 3mHz to 30mHz the errors associated with parameter measurements differ from about 5% up to a factor of 10 (depending on the actual source parameters and emission frequency) with respect to those computed using the long wavelength approximation.Comment: replacement version with typos correcte

Discrete Model of Ideological Struggle Accounting for Migration

A discrete in time model of ideological competition is formulated taking into account population migration. The model is based on interactions between global populations of non-believers and followers of different ideologies. The complex dynamics of the attracting manifolds is investigated. Conversion from one ideology to another by means of (i) mass media influence and (ii) interpersonal relations is considered. Moreover a different birth rate is assumed for different ideologies, the rate being assumed to be positive for the reference population, made of initially non-believers. Ideological competition can happen in one or several regions in space. In the latter case, migration of non-believers and adepts is allowed; this leads to an enrichment of the ideological dynamics. Finally, the current ideological situation in the Arab countries and China is commented upon from the point of view of the presently developed mathematical model. The massive forced conversion by Ottoman Turks in the Balkans is briefly discussed.Comment: 24 pages, with 5 figures and 52 refs.; prepared for a Special issue of Advances in Complex System

Fast Domain Growth through Density-Dependent Diffusion in a Driven Lattice Gas

We study electromigration in a driven diffusive lattice gas (DDLG) whose continuous Monte Carlo dynamics generate higher particle mobility in areas with lower particle density. At low vacancy concentrations and low temperatures, vacancy domains tend to be faceted: the external driving force causes large domains to move much more quickly than small ones, producing exponential domain growth. At higher vacancy concentrations and temperatures, even small domains have rough boundaries: velocity differences between domains are smaller, and modest simulation times produce an average domain length scale which roughly follows $L \sim t^{\zeta}$, where $\zeta$ varies from near .55 at 50% filling to near .75 at 70% filling. This growth is faster than the $t^{1/3}$ behavior of a standard conserved order parameter Ising model. Some runs may be approaching a scaling regime. At low fields and early times, fast growth is delayed until the characteristic domain size reaches a crossover length which follows $L_{cross} \propto E^{-\beta}$. Rough numerical estimates give $\beta= >.37$ and simple theoretical arguments give $\beta= 1/3$. Our conclusion that small driving forces can significantly enhance coarsening may be relevant to the YB$_2$Cu$_3$O$_{7- \delta}$ electromigration experiments of Moeckly {\it et al.}(Appl. Phys. Let., {\bf 64}, 1427 (1994)).Comment: 18 pages, RevTex3.