A stochastic model for the evolution of the Web

Recently several authors have proposed stochastic models of the growth of the Web graph that give rise to power-law distributions. These models are based on the notion of preferential attachment leading to the "rich get richer" phenomenon. However, these models fail to explain several distributions arising from empirical results, due to the fact that the predicted exponent is not consistent with the data. To address this problem, we extend the evolutionary model of the Web graph by including a non-preferential component, and we view the stochastic process in terms of an urn transfer model. By making this extension, we can now explain a wider variety of empirically discovered power-law distributions provided the exponent is greater than two. These include: the distribution of incoming links, the distribution of outgoing links, the distribution of pages in a Web site and the distribution of visitors to a Web site. A by-product of our results is a formal proof of the convergence of the standard stochastic model (first proposed by Simon)

Quantification and Statistical Analysis of Structural Similarities in Dialectological Area-Class Maps

Some of the main aims of dialectology have always been the division of a given geographic space into areas where different dialects are spoken, the detection of dialect boundaries, and the investigation of the strength of these boundaries. For this purpose, a sub-discipline of dialectology, „dialectometry‟, has introduced the method of counting or measuring the differences between lects spoken at different locations. (For a concise overview of dialectometric methods, see, for example, HEERINGA 2004, 9–24.) The higher the number or degree of differences between two locations are, the higher is the chance that they are placed in two disjoint dialect areas. This implies, however, that each pair of locations sometimes exhibits agreement, sometimes disagreement, even within one dialect area. Otherwise, there would only be completely disjoint, mutually unintelligible lects. Instead, we find that while some of the variants fit neatly into the dialect areas, others show somewhat divergent or even completely different geographical distributions. Consequently, the distributions of single variants must be considered more than mere deviations from one underlying pattern as represented by the dialect areas; in fact, they differ so greatly from one another that they need to be studied, too.The project is funded by the DFG (Deutsche Forschungsgemeinschaft)

Annealing of nanoindentation-induced high pressure crystalline phases created in crystalline and amorphous silicon

Thermally induced phase transformation of Si-III/Si-XII zones formed by nanoindentation has been studied during low temperature (200<T<300 °C) thermal annealing by Raman microspectroscopy and transmission electron microscopy. Two sizes of spherical indenter tips have been used to create substantially different volumes of phase transformed zones in both crystalline (c-Si) and amorphous silicon (a-Si) to study the zone size and starting matrix effects. The overall transformation is from Si-III/XII to poly- or nanocrystalline Si-I through intermediate phases of Si-XIII and Si-IV. Attempts have been made to determine the exact transformation pathways. Two scenarios are possible: either Si-XII first transforms to Si-III before transforming to Si-I through the intermediate phases or that Si-XII goes through the intermediate phases while Si-III transforms directly to Si-I. Finally, the phase transformations are slower in the larger indents and the starting matrix (crystalline or amorphous) has a substantial effect on the transformation kinetics of the small indents compared to the larger ones. We attribute this increased stability to both matrix effects (nucleation) and a difference in overall residual stress in indents made in a-Si compared to c-Si

A importância de novos meios tecnológicos na detecção do segundo canal mesiovestibular em tratamento endodôntico dos primeiros e segundos molares superiores

A anatomia do primeiro e do segundo molar superior dificulta a realização do tratamento endodôntico. A presença frequente de um quarto canal localizado dentro da raiz mésiovestibular pode representar um desafio para o clínico. Vários estudos mostram que a dificuldade em localizar e tratar o segundo canal mesiovestibular dos molares superiores pode levar ao insucesso do tratamento endodôntico e o risco de desenvolver infecção/inflamação. Ao longo dos anos, a tecnologia evoluiu, permitindo ao clínico aumentar o sucesso dos seus tratamentos dentários. De fato, os dados atuais mostram que o uso do microscópio, das lupas e da tomografia computadorizada de feixe cónico permite melhorar a detecção do segundo canal mesiovestibular dos molares superiores. Esta revisão sistemática tem como objectivo reuniar evidências ciêntificas que nos ajudem a compreender qual dos meios tecnológicos atuais é o mais eficaz na detecção e localização do segundo canal mesiovestibular do primeiro e segundo molares superiores

Gahnite composition as a means to fingerprint metamorphosed massive sulfide and non-sulfide zinc deposits

Gahnite occurs in and around metamorphosed massive sulfide (e.g., Broken Hill-type Pb–Zn–Ag (BHT), volcanogenic massive sulfide Cu–Zn–Pb–Au–Ag (VMS), sedimentary exhalative Pb–Zn (SEDEX)), and nonsulfide zinc (NSZ) deposits. In addition to occurring in situ, gahnite occurs as a resistate indicator mineral in unconsolidated sediments (e.g., glacial till) surrounding such deposits. The spatial association between gahnite and metamorphosed ore deposits has resulted in its use as an empirical exploration guide to ore. Major and trace element compositions of gahnite from BHT, NSZ, SEDEX, and VMS deposits are used here to develop geochemical fingerprints for each deposit type. A classification tree diagram, using a combination of six discrimination plots, is presented here to identify the provenance of detrital gahnite in greenfield and brownfield terranes, which can be used as an exploration guide to metamorphosed massive sulfide and non-sulfide zinc deposits. The composition of gahnite in BHT deposits is discriminated from gahnite in SEDEX and VMS deposits on the basis of plots of Mg versus V, and Co versus V. Gahnite in SEDEX deposits can be distinguished from that in VMS deposits using plots of Co versus V, Mn versus Ti, and Co versus Ti. In the Sterling Hill NSZ deposit, gahnite contains higher concentrations of Fe3+ and Cd, and lower amounts of Al, Mg, and Co than gahnite in BHT, SEDEX, and VMS deposits. Plots of Co versus Cd, and Al versus Mg distinguish gahnite in the Sterling Hill NSZ deposit from the other types of deposits

The relationship between religious involvement and clinical status of patients with bipolar disorder

Cruz M, Pincus HA, Welsh DE, Greenwald D, Lasky E, Kilbourne AM. The relationship between religious involvement and clinical status of patients with bipolar disorder. Bipolar Disord 2010: 12: 68–76. © 2010 The Authors. Journal compilation © 2010 John Wiley & Sons A/S.Religion and spirituality are important coping strategies in depression but have been rarely studied within the context of bipolar disorder. The present study assessed the association between different forms of religious involvement and the clinical status of individuals treated for bipolar disorder.A cross-sectional observation study of follow-up data from a large cohort study of patients receiving care for bipolar disorder (n = 334) at an urban Veterans Affairs mental health clinic was conducted. Bivariate and multivariate analyses were performed to assess the association between public (frequency of church attendance), private (frequency of prayer/meditation), as well as subjective forms (influence of beliefs on life) of religious involvement and mixed, manic, depressed, and euthymic states when demographic, anxiety, alcohol abuse, and health indicators were controlled.Multivariate analyses found significant associations between higher rates of prayer/meditation and participants in a mixed state [odds ratio (OR) = 1.29; 95% confidence interval (CI) = 1.10–1.52, chi square = 9.42, df = 14, p < 0.05], as well as lower rates of prayer/meditation and participants who were euthymic (OR = 0.84; 95% CI = 0.72–0.99, chi square = 4.60, df = 14, p < 0.05). Depression and mania were not associated with religious involvement.Compared to patients with bipolar disorder in depressed, manic, or euthymic states, patients in mixed states have more active private religious lives. Providers should assess the religious activities of individuals with bipolar disorder in mixed states and how they may complement/deter ongoing treatment. Future longitudinal studies linking bipolar states, religious activities, and treatment-seeking behaviors are needed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78616/1/j.1399-5618.2009.00772.x.pd

Unhatched eggs represent the invisible fraction in two wild bird populations

Prenatal mortality is typically overlooked in population studies, which biases evolutionary inference by confounding selection and inheritance. Birds represent an opportunity to include this ‘invisible fraction’ if each egg contains a zygote, but whether hatching failure is caused by fertilization failure versus prenatal mortality is largely unknown. We quantified fertilization failure rates in two bird species that are popular systems for studying evolutionary dynamics and found that overwhelming majorities (99.9%) of laid eggs were fertilized. These systems thus present opportunities to eliminate the invisible fraction from life-history data

A Detailed Investigation into Low-Level Feature Detection in Spectrogram Images

Being the first stage of analysis within an image, low-level feature detection is a crucial step in the image analysis process and, as such, deserves suitable attention. This paper presents a systematic investigation into low-level feature detection in spectrogram images. The result of which is the identification of frequency tracks. Analysis of the literature identifies different strategies for accomplishing low-level feature detection. Nevertheless, the advantages and disadvantages of each are not explicitly investigated. Three model-based detection strategies are outlined, each extracting an increasing amount of information from the spectrogram, and, through ROC analysis, it is shown that at increasing levels of extraction the detection rates increase. Nevertheless, further investigation suggests that model-based detection has a limitation—it is not computationally feasible to fully evaluate the model of even a simple sinusoidal track. Therefore, alternative approaches, such as dimensionality reduction, are investigated to reduce the complex search space. It is shown that, if carefully selected, these techniques can approach the detection rates of model-based strategies that perform the same level of information extraction. The implementations used to derive the results presented within this paper are available online from http://stdetect.googlecode.com