178,212 research outputs found
R script of Grassi Talamini Lazzerini: Pitch discrimination of low and high pitch tones by bassists, violinists and nonmusicians
No full textR script to analyze the data of Grassi Talamini Lazzerini<br
Canonical bases of invariant polynomials for the irreducible reflection groups of types E6, E7, and E8
No full textGiven a rank n irreducible finite reflection group W, the W-invariant polynomial functions defined in R^n can be written as polynomials of n algebraically independent homogeneous polynomial functions, p_1(x),...,p_n(x), called basic invariant polynomials. Their degrees are well known and typical of the given group W. The polynomial p_1(x) has the lowest degree, equal to 2. It has been proved that it is possible to choose all the other n−1 basic invariant polynomials in such a way that they satisfy a certain system of differential equations, including the Laplace equations △p_a(x)=0, a=2,...,n, and so are harmonic functions. Bases of this kind are called canonical. Explicit formulas for canonical bases of invariant polynomials have been found for all irreducible finite reflection groups, except for those of types E_6, E_7 and E_8. Those for the groups of types E_6, E_7 and E_8 are determined in this article
Universality in orbit spaces of compact linear groups
No full textIf {p_1(x), ..., p_q(x)} is a minimal integrity basis of the ideal of polynomial invariants of a compact coregular linear group G, the orbit map p=(p_1(x) .... ,p_q(x)):R^n->R^q,
yields a diffeomorphic image S = p(R^n) \subset R^q of the orbit space R^n/G. Starting from this fact, we point out some properties which are common to the orbit spaces of all the compact coregular linear groups of transformations of R^n. In particular we show that a contravariant metric matrix P(p) can be defined in the interior of S, as
a polynomial function of (p_1, ...,p_q). We prove that the matrix P(p), which characterizes the set S, as it is positive semi-definite only for p \in S, can be determined as a solution of a canonical differential equation, which, for every compact coregular linear group, depends only on the number q and on the degrees of the elements of the minimal integrity bases. This allows to determine all the
isomorphism classes of the orbit spaces of the compact coregular linear groups through a determination of the equivalence classes of the corresponding matrices
P(p). For q<3 (orbit spaces with dimensions < 3), the solutions P(p) of the canonical equation are explicitly determined and the number of their equivalence
classes is shown to be finite. It is also shown that, with a convenient choice of the minimal integrity basis, the polynomial matrix elements of P(p) have only integer
coefficients. Arguments are given in favour of the conjecture that our conclusions hold true for all values of q. Our results are relevant and lead to universality properties in the physics of spontaneous symmetry breaking
Oral contraceptives and cervical neoplasia: pooled information from retrospective and prospective epidemiologic studies
No full textA positive association between the use of oral contraceptives and the risk of cervical neoplasia has been suggested by different sources. This paper examines epidemiologic evidence on this issue through pooled computation of relative risks emerging from 21 studies, subdivided into three main categories: studies based on routine cytologic screening programs, case-control investigations and prospective studies. The pooled estimates of the relative risks for ever vs never use of oral contraceptives were broadly similar and slightly above unity (1.4 from cytologic screening programs, 1.1 from case-control and 1.4 from prospective studies). The risk increased with duration of use and, generally, lower relative risk estimates derived from the older studies, necessarily based on short-term use of oral contraceptives. A particularly limited increase in risk was apparent from case-control investigations. Furthermore, when allowance was made for the major covariates (mostly indicators of sexual habits), a noticeable decrease in the excess risk was evident. In conclusion, although statistical significance of moderate differences in risk can be obtained by pooling data from several studies, a risk of the magnitude of that for the association between oral contraceptives and cervical neoplasia may well be due to bias and confounding. In addition, since sexual behavior only indicates the probability of having been exposed to some sexually transmitted agent (most likely human papilloma virus), the greatest additional contribution may come from a case-control study in which adjustment for such exposure is possible
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Joint effects of family history and adult life dietary risk factors on colorectal cancer risk
No full textBackground. We analyzed the joint effects of family history of colorectal cancer and adult life dietary risk factors on colorectal cancer risk. Methods. We used data from a case-control study conducted in northern Italy between 1985 and 1992, including 1584 cases with colorectal cancer and 2879 controls. We created an adult life dietary risk factor score. Results. Among subjects with family history of colorectal cancer, those in the lowest risk score tertile were not at elevated risk of colorectal cancer (odds ratio = 1.2; 95% confidence interval = 0.7-2.1), whereas those in the highest score tertile were at increased risk (odds ratio = 5.5; 95% confidence interval = 3.5-8.7). Conclusions. These findings indicate that the expression of familial susceptibility can be substantially modified by adult life risk factors. RI Fernandez, Esteve/A-9750-200
Natural history of atypical and equivocal melanocytic lesions in children: An observational study of 19 cases
No full textDigital dermoscopy follow-up helps to identify patterns of change typical of common atypical nevi and early melanoma and improves the follow-up of patients with atypical nevi. We report the morphologic changes observed over time in 19 atypical or equivocal acquired melanocytic nevi that underwent dermoscopic follow-up. Two observers retrospectively examined digitalized dermoscopic images of 19 atypical melanocytic nevi from 15 children and young adults (median age 12 years, range 3-26 years). The images were assessed for global dermoscopic patterns at baseline and after a median 25-month (range 6-138 mos) follow-up. Ten (52.6%) nevi changed and nine (47.4%) retained a stable dermoscopic pattern. Of the 10 changing lesions, 2 of 4 homogeneous nevi evolved into a reticular pattern and 2 into a mixed pattern; 1 of 2 nevi with a mixed pattern evolved into a homogeneous nevus and 1 into a regressing nevus; 1 of 2 nevi with "other" patterns, such as negative pigment network and peppering throughout the lesion, evolved into a mixed nevus and 1 into a regressing nevus; 1 globular nevus evolved into a mixed pattern; and 1 starburst nevus evolved into a homogeneous nevus. The most striking results of our study were that atypical nevi can evolve into common nevi or they can regress, as documented by long-term dermoscopic follow-up. In children and young adults, dermoscopic follow-up of atypical nevi might be a valid alternative to surgical excision and enables us to achieve new insights into the natural history of these nevi
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Genital and urinary tract diseases and prostate cancer risk
No full textThe objectives of this study were to investigate whether venereal diseases, prostatic and urinary infections, and other selected conditions of the genital and urinary tracts may have a role in the development of prostate cancer. We analysed data from a hospital-based case-control study conducted between 1985 and 1992 in Italy, including 280 cases of prostatic cancer and 689 controls, hospitalized for acute, non-neoplastic, non-genital or urinary tract conditions. We calculated odds ratios and 95% confidence intervals using unconditional multiple logistic regression. The odds ratios of prostate cancer were 0.64 for history of selected venereal diseases, 0.53 for prostatitis, 0.67 for benign prostatic hyperplasia, 1.53 for urinary tract stones and 1.76 for cystitis. No relationship, however, was observed for cystitis &rt; 5 years before prostate cancer. The present study, based on satisfactorily reproducible information on medical history, did not found any association between genital and urinary tract diseases and prostate cancer risk. European Journal of Cancer Prevention 15:254-257 (c) 2006 Lippincott Williams & Wilkins
- …
