102 research outputs found
Forgetful maps between Deligne-Mostow ball quotients
We study forgetful maps between Deligne-Mostow moduli spaces of weighted
points on P^1, and classify the forgetful maps that extend to a map of
orbifolds between the stable completions. The cases where this happens include
the Livn\'e fibrations and the Mostow/Toledo maps between complex hyperbolic
surfaces. They also include a retraction of a 3-dimensional ball quotient onto
one of its 1-dimensional totally geodesic complex submanifolds
Monodromy of Cyclic Coverings of the Projective Line
We show that the image of the pure braid group under the monodromy action on
the homology of a cyclic covering of degree d of the projective line is an
arithmetic group provided the number of branch points is sufficiently large
compared to the degree.Comment: 47 pages (to appear in Inventiones Mathematicae
Can one hear the shape of the Universe?
It is shown that the recent observations of NASA's explorer mission
"Wilkinson Microwave Anisotropy Probe" (WMAP) hint that our Universe may
possess a non-trivial topology. As an example we discuss the Picard space which
is stretched out into an infinitely long horn but with finite volume.Comment: 4 page
Manifolds with small Dirac eigenvalues are nilmanifolds
Consider the class of n-dimensional Riemannian spin manifolds with bounded
sectional curvatures and diameter, and almost non-negative scalar curvature.
Let r=1 if n=2,3 and r=2^{[n/2]-1}+1 if n\geq 4. We show that if the square of
the Dirac operator on such a manifold has small eigenvalues, then the
manifold is diffeomorphic to a nilmanifold and has trivial spin structure.
Equivalently, if M is not a nilmanifold or if M is a nilmanifold with a
non-trivial spin structure, then there exists a uniform lower bound on the r-th
eigenvalue of the square of the Dirac operator. If a manifold with almost
nonnegative scalar curvature has one small Dirac eigenvalue, and if the volume
is not too small, then we show that the metric is close to a Ricci-flat metric
on M with a parallel spinor. In dimension 4 this implies that M is either a
torus or a K3-surface
Algebraic volume density property of affine algebraic manifolds
We introduce the notion of algebraic volume density property for affine
algebraic manifolds and prove some important basic facts about it, in
particular that it implies the volume density property. The main results of the
paper are producing two big classes of examples of Stein manifolds with volume
density property. One class consists of certain affine modifications of \C^n
equipped with a canonical volume form, the other is the class of all Linear
Algebraic Groups equipped with the left invariant volume form.Comment: 35 page
A simple clinical scoring system to improve the sensitivity and standardization of the diagnosis of mycosis fungoides type cutaneous T-cell lymphoma: logistic regression of clinical and laboratory data
Background The diagnosis of mycosis fungoides (MF) is notoriously difficult to establish because in the early stages, histological features may be nonspecific or merely suggestive. Objectives To standardize the diagnosis of MF. Methods We studied 138 patients with suspected MF referred over a 7-year period to a university department of a dermatology-based cutaneous lymphoma clinic. Six diagnostic criteria were evaluated: clinical morphology, clinical distribution, skin biopsy T-cell receptor gene rearrangement (TCR-GR), skin biopsy pan T-cell marker loss ≥ 2, skin biopsy CD4/CD8 ratio ≥ 6, and skin biopsy diffuse epidermal HLA-DR expression. These six clinical and laboratory criteria were compared by logistic regression analysis in patients with histologically diagnosed MF and those with benign disease. Results Of the 138 patients, 74 had histology of MF, 47 of benign dermatoses and 17 were indeterminate. Close associations were found between a histological diagnosis of MF and TCR-GR (odds ratio 14·4), classical morphology (7·5), classical distribution (2·5) and diffuse epidermal HLA-DR expression (2·8). Logistic regression models were developed depending on the availability of data (either TCR-GR or HLA-DR). Probabilities for correctly diagnosing MF compared with histology as the ‘gold standard’ were derived from these logistic regression models. A scoring system assigning point values based on these probabilities was then created in order to assist the clinician in making the diagnosis. If using TCR-GR data, a positive TCR-GR = 2·5 points, the presence of classical morphology = 2·0 points, and the presence of classical distribution = 1·5 points. A total score of ≥ 3·5 points assigns a high probability (> 85%) of having MF. If using HLA-DR expression, then the presence of classical morphology = 2·5 points, a positive diffuse epidermal HLA-DR expression = 2·0 points, and the presence of classical distribution = 1·5 points. In this case, a total score of ≥ 4·0 points assigns a high probability (> 85%) of MF. Conclusions The logistic regression models and scoring systems integrate clinical and laboratory assessments, allow rapid probability estimation, and provide a threshold for the diagnosis of MF in an objective, standardized manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75520/1/j.1365-2133.2003.05458.x.pd
Remarks on the Configuration Space Approach to Spin-Statistics
The angular momentum operators for a system of two spin-zero
indistinguishable particles are constructed, using Isham's Canonical Group
Quantization method. This mathematically rigorous method provides a hint at the
correct definition of (total) angular momentum operators, for arbitrary spin,
in a system of indistinguishable particles. The connection with other
configuration space approaches to spin-statistics is discussed, as well as the
relevance of the obtained results in view of a possible alternative proof of
the spin-statistics theorem.Comment: 18 page
Compact Hyperbolic Extra Dimensions: Branes, Kaluza-Klein Modes and Cosmology
We reconsider theories with low gravitational (or string) scale M_* where
Newton's constant is generated via new large-volume spatial dimensions, while
Standard Model states are localized to a 3-brane. Utilizing compact hyperbolic
manifolds (CHM's) we show that the spectrum of Kaluza-Klein (KK) modes is
radically altered. This allows an early universe cosmology with normal
evolution up to substantial temperatures, and completely negates the
constraints on M_* arising from astrophysics. Furthermore, an exponential
hierarchy between the usual Planck scale and the true fundamental scale of
physics can emerge with only order unity coefficients. The linear size of the
internal space remains small. The proposal has striking testable signatures.Comment: 4 pages, no figure
The No-defect Conjecture: Cosmological Implications
When the topology of the universe is non trivial, it has been shown that
there are constraints on the network of domain walls, cosmic strings and
monopoles. I generalize these results to textures and study the cosmological
implications of such constraints. I conclude that a large class of
multi-connected universes with topological defects accounting for structure
formation are ruled out by observation of the cosmic microwave background.Comment: 4 pages, 1 figure, accepted for publication as a brief report in
Phys. Rev.
Gender differences in local and systemic reactions to inactivated influenza vaccine, established by a meta-analysis of fourteen independent studies
In order to determine whether there is a difference between genders in reported adverse reactions to inactivated influenza vaccine, a computerized database of serological studies was investigated. A standardized questionnaire was used to evaluate vaccine reactogenicity. A total of 1,800 vaccinees in 14 studies were analyzed separately for two age groups ( or = 60 years of age). Females reported significantly more local reactions than males. The pooled odds ratio for the outcome measure "any local reaction" was 0.32 (95% confidence interval, 0.26-0.40, significant) and 0.54 (95% Cl, 0.41-0.70, significant) for young and elderly adults, respectively. Similar results were obtained for the outcome measure "any systemic reaction." Previous exposure to influenza or influenza vaccine had no influence on reactogenicity. There were no gender differences in sero-responses. In conclusion, gender should be regarded as a predictor of reported reactions to influenza vaccine in both young and elderly adults and should be addressed in future study designs
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