410 research outputs found
Recommended from our members
Agricultural development prospects in Belize (NRI Bulletin 48)
This report is one ofthree documents completing the land resource assessment of Belize undertaken by the Natural Resources Institute (NRI)from 1986-90. The other documents are: (i) a revised national soil classification (Baillie et al., 1993) (ii) an update on 'Land in British Honduras' (Wright et al., 1959), which will present inter alia much of the NRI land resource assessment findings in a more easily readable format (Wright et al., 1993). The aim of this report is to assess the entire··agricultural resources of the country, present an assessment of how they can be used to best effect, both in the short(economically) and long terms (by protecting the environment), and present a 1:500 000 scale map indicating the preferred use for each part of the country (Map 1 ). Map 1 does not take into account current ownership, except in the case of Programme for Belize, where it is assumed that organization will continue to manage the Rio Bravo Conservation Management Area. This report also includes advice on how a Geographical Information System (GIS) can be used to update the NRI surveys and provide additional data so that the suitability of new crops and the effect of changed economic circumstances can be determined from the land resource assessment database
Volume Comparison for Hypersurfaces in Lorentzian Manifolds and Singularity Theorems
We develop area and volume comparison theorems for the evolution of
spacelike, acausal, causally complete hypersurfaces in Lorentzian manifolds,
where one has a lower bound on the Ricci tensor along timelike curves, and an
upper bound on the mean curvature of the hypersurface. Using these results, we
give a new proof of Hawking's singularity theorem.Comment: 15 pages, LaTe
Elevated Levels of Trace Elements in Cores of Otoliths and Their Potential for Use as Natural Tags
Variation in the chemical composition of fish otoliths has been used in recent years to address a range of ecological questions, including levels of stock mixing, variation in habitat use, and rates of larval exchange. While some of these questions have been answered with varying success, the degree to which discrete populations are connected via larval exchange remains unknown. To identify larval sources using natural variation in otolith chemistry, we must distinguish and measure the chemical composition of the otolith core, the portion of the otolith formed at the spawning site. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), we found that the core regions of otoliths from 6 different species of fishes were highly enriched in manganese (Mn), and elevated in magnesium (Mg) and barium (Ba), relative to adjacent regions of the otolith. These patterns were consistent for species drawn from different taxonomic groups, which inhabit temperate and tropical regions, are found in marine and freshwater, and utilize a variety of spawning modes. Variation among species in Mn concentration in the core also corresponds to maternal investment, measured by egg size. These data suggest that core enrichment may be a general characteristic of otoliths, and that the chemical composition of the otolith core is fundamentally different from other regions of the otolith. The localized elemental enrichment of the core underscores the importance of methods that analyze the core region in small, discrete samples if otolith chemistry is used to address questions of larval exchange among populations
A (Running) Bolt for New Reasons
We construct a four-parameter family of smooth, horizonless, stationary
solutions of ungauged five-dimensional supergravity by using the
four-dimensional Euclidean Schwarzschild metric as a base space and
"magnetizing" its bolt. We then generalize this to a five-parameter family
based upon the Euclidean Kerr-Taub-Bolt. These "running Bolt" solutions are
necessarily non-static. They also have the same charges and mass as a
non-extremal black hole with a classically-large horizon area. Moreover, in a
certain regime their mass can decrease as their charges increase. The existence
of these solutions supports the idea that the singularities of non-extremal
black holes are resolved by low-mass modes that correct the singularity of the
classical black hole solution on large (horizon-sized) scales.Comment: 25 pages, 3 figures, LaTeX; v2: minor changes, references adde
Multi-Center non-BPS Black Holes - the Solution
We construct multi-center, non-supersymmetric four-dimensional solutions
describing a rotating anti-D6-D2 black hole and an arbitrary number of D4-D2-D0
black holes in a line. These solutions correspond to an arbitrary number of
extremal non-BPS black rings in a Taub-NUT space with a rotating three-charge
black hole in the middle. The positions of the centers are determined by
solving a set of "bubble" or "integrability" equations that contain cubic
polynomials of the inter-center distance, and that allow scaling solutions even
when the total four-dimensional angular momentum of the scaling centers is
non-zero.Comment: 16 pages, LaTe
Signals for Lorentz Violation in Electrodynamics
An investigation is performed of the Lorentz-violating electrodynamics
extracted from the renormalizable sector of the general Lorentz- and
CPT-violating standard-model extension. Among the unconventional properties of
radiation arising from Lorentz violation is birefringence of the vacuum. Limits
on the dispersion of light produced by galactic and extragalactic objects
provide bounds of 3 x 10^{-16} on certain coefficients for Lorentz violation in
the photon sector. The comparative spectral polarimetry of light from
cosmologically distant sources yields stringent constraints of 2 x 10^{-32}.
All remaining coefficients in the photon sector are measurable in
high-sensitivity tests involving cavity-stabilized oscillators. Experimental
configurations in Earth- and space-based laboratories are considered that
involve optical or microwave cavities and that could be implemented using
existing technology.Comment: 23 pages REVTe
Pituitary blastoma: a pathognomonic feature of germ-line DICER1 mutations.
Individuals harboring germ-line DICER1 mutations are predisposed to a rare cancer syndrome, the DICER1 Syndrome or pleuropulmonary blastoma-familial tumor and dysplasia syndrome [online Mendelian inheritance in man (OMIM) #601200]. In addition, specific somatic mutations in the DICER1 RNase III catalytic domain have been identified in several DICER1-associated tumor types. Pituitary blastoma (PitB) was identified as a distinct entity in 2008, and is a very rare, potentially lethal early childhood tumor of the pituitary gland. Since the discovery by our team of an inherited mutation in DICER1 in a child with PitB in 2011, we have identified 12 additional PitB cases. We aimed to determine the contribution of germ-line and somatic DICER1 mutations to PitB. We hypothesized that PitB is a pathognomonic feature of a germ-line DICER1 mutation and that each PitB will harbor a second somatic mutation in DICER1. Lymphocyte or saliva DNA samples ascertained from ten infants with PitB were screened and nine were found to harbor a heterozygous germ-line DICER1 mutation. We identified additional DICER1 mutations in nine of ten tested PitB tumor samples, eight of which were confirmed to be somatic in origin. Seven of these mutations occurred within the RNase IIIb catalytic domain, a domain essential to the generation of 5p miRNAs from the 5' arm of miRNA-precursors. Germ-line DICER1 mutations are a major contributor to PitB. Second somatic DICER1 "hits" occurring within the RNase IIIb domain also appear to be critical in PitB pathogenesis
Accretion, Outflows, and Winds of Magnetized Stars
Many types of stars have strong magnetic fields that can dynamically
influence the flow of circumstellar matter. In stars with accretion disks, the
stellar magnetic field can truncate the inner disk and determine the paths that
matter can take to flow onto the star. These paths are different in stars with
different magnetospheres and periods of rotation. External field lines of the
magnetosphere may inflate and produce favorable conditions for outflows from
the disk-magnetosphere boundary. Outflows can be particularly strong in the
propeller regime, wherein a star rotates more rapidly than the inner disk.
Outflows may also form at the disk-magnetosphere boundary of slowly rotating
stars, if the magnetosphere is compressed by the accreting matter. In isolated,
strongly magnetized stars, the magnetic field can influence formation and/or
propagation of stellar wind outflows. Winds from low-mass, solar-type stars may
be either thermally or magnetically driven, while winds from massive, luminous
O and B type stars are radiatively driven. In all of these cases, the magnetic
field influences matter flow from the stars and determines many observational
properties. In this chapter we review recent studies of accretion, outflows,
and winds of magnetized stars with a focus on three main topics: (1) accretion
onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and
(3) winds from isolated massive magnetized stars. We show results obtained from
global magnetohydrodynamic simulations and, in a number of cases compare global
simulations with observations.Comment: 60 pages, 44 figure
Trajectories of Big Five Personality Traits: A Coordinated Analysis of 16 Longitudinal Samples
This study assessed change in self‐reported Big Five personality traits. We conducted a coordinated integrative data analysis using data from 16 longitudinal samples, comprising a total sample of over 60 000 participants. We coordinated models across multiple datasets and fit identical multi‐level growth models to assess and compare the extent of trait change over time. Quadratic change was assessed in a subset of samples with four or more measurement occasions. Across studies, the linear trajectory models revealed declines in conscientiousness, extraversion, and openness. Non‐linear models suggested late‐life increases in neuroticism. Meta‐analytic summaries indicated that the fixed effects of personality change are somewhat heterogeneous and that the variability in trait change is partially explained by sample age, country of origin, and personality measurement method. We also found mixed evidence for predictors of change, specifically for sex and baseline age. This study demonstrates the importance of coordinated conceptual replications for accelerating the accumulation of robust and reliable findings in the lifespan developmental psychological sciences. © 2020 European Association of Personality PsychologyPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/156004/1/per2259.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/156004/2/per2259-sup-0001-Data_S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/156004/3/per2259-sup-0002-Open_Practices_Disclosure_Form.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/156004/4/per2259_am.pd
- …