429 research outputs found
Some Comments on the Class of \u2772
Most readers of this publication were at one time admitted to the University of Michigan Law School. Presumably most of our readers feel that getting admitted was a good thing, and would be interested in knowing what sort of people are following in their footstep. In years gone by the admissions officer could simply rely on the increasing number of applicants to produce a higher average undergraduate record and a spectacular average score on the Law School Admiaaion Test (LSAT). This year the 1st-year class has very good grades and test scores, but there is more to the story than just the crush of numbers
Woodstock Nation Goes to Law School
Friends of The University of Michigan Law School might wonder, in these times of campus tumult, if the wise undergraduate is directing his steps elsewhere. In fact just the opposite of what one might assume is true. Michigan, Harvard, and Berkeley, all active campi, have all had extremely large numbers of applicants to their law schools. In 1969-70 the Admissions Office had 4,000 applications, almost a thousand more than in the previous year, which in turn had also set a record. It is comforting to know that so many college seniors have such high regard for Michigan-garnered in the main from contacts with alumni, students, and faculty, one assumes, and not from the lure of student protest-but when viewed in any other light, 4,000 is too many
Variable Step Random Walks and Self-Similar Distributions
We study a scenario under which variable step random walks give anomalous
statistics. We begin by analyzing the Martingale Central Limit Theorem to find
a sufficient condition for the limit distribution to be non-Gaussian. We note
that the theorem implies that the scaling index is 1/2. For
corresponding continuous time processes, it is shown that the probability
density function satisfies the Fokker-Planck equation. Possible forms
for the diffusion coefficient are given, and related to . Finally, we
show how a time-series can be used to distinguish between these variable
diffusion processes and L\'evy dynamics.Comment: 13pages, 2 figure
Determinants of Agricultural Pesticide Concentrations in Carpet Dust
Background: Residential proximity to agricultural pesticide applications has been used as a surrogate for exposure in epidemiologic studies, although little is known about the relationship with levels of pesticides in homes
Host plant quality, spatial heterogeneity, and the stability of mite predator–prey dynamics
Population dynamics models suggest that both the over-all level of resource productivity and spatial variability in productivity can play important roles in community dynamics. Higher productivity environments are predicted to destabilize consumer–resource dynamics. Conversely, greater heterogeneity in resource productivity is expected to contribute to stability. Yet the importance of these two factors for the dynamics of arthropod communities has been largely overlooked. I manipulated nutrient availability for strawberry plants in a multi-patch experiment, and measured effects of overall plant quality and heterogeneity in plant quality on the stability of interactions between the phytophagous mite Tetranychus urticae and its predator Phytoseiulus persimilis. Plant size, leaf N content and T. urticae population growth increased monotonically with increasing soil nitrogen availability. This gradient in plant quality affected two correlates of mite population stability, population variability over time (i.e., coefficient of variation) and population persistence (i.e., proportion of plant patches colonized). However, the highest level of plant quality did not produce the least stable dynamics, which is inconsistent with the “paradox of enrichment”. Heterogeneity in plant productivity had modest effects on stability, with the only significant difference being less variable T. urticae densities in the heterogeneous compared to the corresponding homogeneous treatment. These results are generally congruent with metapopulation theory and other models for spatially segregated populations, which predict that stability should be governed largely by relative movement rates of predators and prey—rather than patch quality
Modern microwave methods in solid state inorganic materials chemistry: from fundamentals to manufacturing
No abstract available
Maternally Acquired Zika Antibodies Enhance Dengue Disease Severity in Mice
Antibody (Ab)-dependent enhancement can exacerbate dengue virus (DENV) infection due to cross-reactive Abs from an initial DENV infection, facilitating replication of a second DENV. Zika virus (ZIKV) emerged in DENV-endemic areas, raising questions about whether existing immunity could affect these related flaviviruses. We show that mice born with circulating maternal Abs against ZIKV develop severe disease upon DENV infection. Compared with pups of naive mothers, those born to ZIKV-immune mice lacking type I interferon receptor in myeloid cells (LysMCre+Ifnar1fl/fl) exhibit heightened disease and viremia upon DENV infection. Passive transfer of IgG isolated from mice born to ZIKV-immune mothers resulted in increased viremia in naive recipient mice. Treatment with Abs blocking inflammatory cytokine tumor necrosis factor linked to DENV disease or Abs blocking DENV entry improved survival of DENV-infected mice born to ZIKV-immune mothers. Thus, the maternal Ab response to ZIKV infection or vaccination might predispose to severe dengue disease in infants
Mosaic Origins of a Complex Chimeric Mitochondrial Gene in Silene vulgaris
Chimeric genes are significant sources of evolutionary innovation that are normally created when portions of two or more protein coding regions fuse to form a new open reading frame. In plant mitochondria astonishingly high numbers of different novel chimeric genes have been reported, where they are generated through processes of rearrangement and recombination. Nonetheless, because most studies do not find or report nucleotide variation within the same chimeric gene, evolution after the origination of these chimeric genes remains unstudied. Here we identify two alleles of a complex chimera in Silene vulgaris that are divergent in nucleotide sequence, genomic position relative to other mitochondrial genes, and expression patterns. Structural patterns suggest a history partially influenced by gene conversion between the chimeric gene and functional copies of subunit 1 of the mitochondrial ATP synthase gene (atp1). We identified small repeat structures within the chimeras that are likely recombination sites allowing generation of the chimera. These results establish the potential for chimeric gene divergence in different plant mitochondrial lineages within the same species. This result contrasts with the absence of diversity within mitochondrial chimeras found in crop species
The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets
This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics
Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.
Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis
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