New or Incompletely Known Species of Feltria from North America (Acarina: Feltriidae)

The genus Feltria has a widespread Holarctic distribution. A few species (Lundblad, 1941, 1969) have also been reported from northern Burma but this latter area. as far as its water mite fauna is concerned, might better be considered part of the southern border of the Palearctic, rather than a part of the Oriental Region. Previously. thirty apparently valid species and subspecies of Feltria were known from North America. The present paper describes nine additional forms and brings the total from the Nearctic area to 39, which is nearly identical with the number known from Europe. Most North American species are found in mountainous regions, but four are known from cold streams and springs in Michigan. The majority of Nearctic species are found associated with mosses and other matted aquatic plants, but twelve (including four described in this paper) are typically residents of the interstitial water associated with stream sand and gravel deposits. For reasons to be listed along with the description of Feltria testudo n. sp., the genus Azugofeltria is reduced to the rank of subgenus. The terminology used in describing musclt: attachment plates and glandularia of the dorsum follows that of Cook (1961). In presenting measurements, those of the holotype and allotype are given first. If a series of specimens is available, the range of variation is given in parentheses following the measurements of the primary types. Holotypes and allotypes will be deposited in the Field Museum of Natural History (Chicago)

Arcs in a finite projective plane

The projective plane of order 11 is the dominant focus of this work. The motivation for working in the projective plane of order 11 is twofold. First, it is the smallest projective plane of prime power order such that the size of the largest (n, r)-arc is not known for all r ∈ {2,...,q + 1}. It is also the smallest projective plane of prime order such that the (n; 3)-arcs are not classified. Second, the number of (n, 3)-arcs is significantly higher in the projective plane of order 11 than it is in the projective plane of order 7, giving a large number of (n, 3)-arcs for study. The main application of (n, r)-arcs is to the study of linear codes. As a forerunner to the work in the projective plane of order eleven two algorithms are used to raise the lower bound on the size of the smallest complete n-arc in the projective plane of order thirty-one from 12 to 13. This work presents the classification up to projective equivalence of the complete (n, 3)- arcs in PG(2, 11) and the backtracking algorithm that is used in its construction. This algorithm is based on the algorithm used in [3]; it is adapted to work on (n, 3)-arcs as opposed to n-arcs. This algorithm yields one representative from every projectively inequivalent class of (n, 3)-arc. The equivalence classes of complete (n, 3)-arcs are then further classified according to their stabilizer group. The classification of all (n, 3)-arcs up to projective equivalence in PG(2, 11) is the foundation of an exhaustive search that takes one element from every equivalence class and determines if it can be extended to an (n′, 4)-arc. This search confirmed that in PG(2, 11) no (n, 3)-arc can be extended to a (33, 4)-arc and that subsequently m4(2, 11) = 32. This same algorithm is used to determine four projectively inequivalent complete (32, 4)-arcs, extended from complete (n, 3)-arcs. Various notions under the general title of symmetry are defined both for an (n, r)-arc and for sets of points and lines. The first of these makes the classification of incomplete (n; 3)- arcs in PG(2, 11) practical. The second establishes a symmetry based around the incidence structure of each of the four projectively inequivalent complete (32, 4)-arcs in PG(2, 11); this allows the discovery of their duals. Both notions of symmetry are used to analyze the incidence structure of n-arcs in PG(2, q), for q = 11, 13, 17, 19. The penultimate chapter demonstrates that it is possible to construct an (n, r)-arc with a stabilizer group that contains a subgroup of order p, where p is a prime, without reference to an (m < n, r)-arc, with stabilizer group isomorphic to ℤ1. This method is used to find q-arcs and (q + 1)-arcs in PG(2, q), for q = 23 and 29, supporting Conjecture 6.7. The work ends with an investigation into the effect of projectivities that are induced by a matrix of prime order p on the projective planes. This investigation looks at the points and subsets of points of order p that are closed under the right action of such matrices and their structure in the projective plane. An application of these structures is a restriction on the size of an (n, r)-arc in PG(2, q) that can be stabilized by a matrix of prime order p

Testing predictor contributions in sufficient dimension reduction

We develop tests of the hypothesis of no effect for selected predictors in regression, without assuming a model for the conditional distribution of the response given the predictors. Predictor effects need not be limited to the mean function and smoothing is not required. The general approach is based on sufficient dimension reduction, the idea being to replace the predictor vector with a lower-dimensional version without loss of information on the regression. Methodology using sliced inverse regression is developed in detail

North American Species of the Genus Axonopsis (Acarina: Aturidae: Axonopsinae)

(excerpt) Members of the genus Axonopsis have a broad zoogeographic distribution but are unreported from the Australian region and South America south of Colombia. Species occur in permanent standing waters and streams (including interstitial water). Representa- tives of four subgenera, Axonopsis s. s., Brachypodopsis, Paraxonopsis and Vicinaxonopsis, have been collected in North America, and a species of the closely related genus Erebaxonopsis is also known from interstitial waters in California. The only anomalous aspects of the distributional patterns are the apparent absence of Hexaxonopsis (which has a relatively widespread Palearctic range) and the stream (and interstitial) habitat of the North American species of the typical subgenus. The European species occurs only in lakes

Fisher Lecture: Dimension Reduction in Regression

Beginning with a discussion of R. A. Fisher's early written remarks that relate to dimension reduction, this article revisits principal components as a reductive method in regression, develops several model-based extensions and ends with descriptions of general approaches to model-based and model-free dimension reduction in regression. It is argued that the role for principal components and related methodology may be broader than previously seen and that the common practice of conditioning on observed values of the predictors may unnecessarily limit the choice of regression methodology.Comment: This paper commented in: [arXiv:0708.3776], [arXiv:0708.3777], [arXiv:0708.3779]. Rejoinder in [arXiv:0708.3781]. Published at http://dx.doi.org/10.1214/088342306000000682 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

North American Species of the Genus Hydrochoreutes (Acarina: Pionidae)

Excerpt: Members of the water mite genus Hydrochoreutes have a Holarctic distribution. They are found in lakes, ponds, and sluggish streams, but usually only in small numbers and therefore long series of specimens are difficult to obtain. Two species, ungulatus (Koch) and krameri Piersig, have a widespread range in Europe and Siberia and the latter species is also known from Algeria. Marshall (1937) reported ungulatus from Maine, Michigan, Wisconsin and California. However, the present author has seen no specimens from North America which can be assigned to the latter species and the illustrations in Marshall\u27s paper are definitely not those of ungulatus. Therefore. there are no authentic records of the latter species in the New World. Cook (1956) named a new species, intermedius, from North America. Both the description and illustrations are inadequate for the latter and it is treated along with four new species in this paper

Rejoinder: Fisher Lecture: Dimension Reduction in Regression

Rejoinder: Fisher Lecture: Dimension Reduction in Regression [arXiv:0708.3774]Comment: Published at http://dx.doi.org/10.1214/088342307000000078 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

The electronic information desk at Leeds Met

The electronic information desk is the email enquiry service for the library at Leeds Metropolitan University and has now been in operation for five years. The service was set up following a review and redesign of both the library’s provision for supporting students offcampus and of its web pages. The service started as a pilot project in September 2001 and it was decided after one semester to continue it on a permanent basis

Investigation into the combination of complementary MOS and complementary bipolar circuits on a monolithic silicon chip Final report

Combination of complementary MOS and complementary bipolar circuits on monolithic silicon chi