1,335 research outputs found
Long-wavelength aeromagnetic anomalies and deep crustal magnetization in Manitoba and Northwestern Ontario, Canada
A new type of aeromagnetic anomaly map (a long-wavelength anomaly map with anomaly widths in the range 60 km < λ < 4000 km) is presented for the area. It is believed that this group of anomalies represents a physically distinct field. This field shows considerable correlation with the broad features of deep crustal structure as derived from seismic sounding; linear relationships were found between the field and depths to the bottom of the crust and to the boundary between the upper and the lower crustal layers, as well as to the thickness of the lower crustal layer. A theoretical relationship connecting structure on magnetized layers to magnetic anomalies is given showing that the linear relationships are to be expected. It is shown that the lower crustal layer is the most likely source of the anomalies, with an intensity of magnetization of 5.3 X 10-3 emu/cc. It is also indicated that the upper crustal layer could also be the source, but that a shallow plate of magnetization could not explain the anomalies. Thus deep crustal magnetization must (on all interpretations made in the present paper), be responsible for the long-wavelength anomalies. Also, these anomalies are strongly related to major features in surface geology.
ARK: https://n2t.net/ark:/88439/y012135
Permalink: https://geophysicsjournal.com/article/171
 
Large extra dimensions, the galaxy power spectrum and the end of inflation
We consider the production of gravitational KK modes via cosmological
photon-photon and electron-positron annihilation in models with large
factorisable extra dimensions. We place constraints on this production using
recent results from a joint analysis of the power spectra of the 2dF Galaxy
Redshift Survey (2dFGS) and the cosmic microwave background (CMB) anisotropies.
We obtain a more accurate upper limit for the temperature corresponding to
matter-radiation equality and show that, even for the case of 6 extra
dimensions and a fundamental scale of 1 TeV, a period of inflation is required
that ends at a temperature much lower than that of the QCD phase transition.Comment: 12 pages, 2 figures, hadronic branching+typos corrected,accepted in
JHE
Density fluctuations from warm inflation
Thermal fluctuations provide the main source of large scale density
perturbations in warm inflationary models of the early universe. For the first
time, general results are obtained for the power spectrum in the case when the
friction coefficient in the inflaton equation of motion depends on temperature.
A large increase in the amplitude of perturbations occurs when the friction
coefficient increases with temperature. This has to be taken into account when
constructing models of warm inflation. New results are also given for the
thermal fluctuations in the weak regime of warm inflation when the friction
coefficient is relatively small.Comment: 14 pages, 4 figures, ReVTe
Large non-Gaussianity from two-component hybrid inflation
We study the generation of non-Gaussianity in models of hybrid inflation with
two inflaton fields, (2-brid inflation). We analyse the region in the parameter
and the initial condition space where a large non-Gaussianity may be generated
during slow-roll inflation which is generally characterised by a large f_NL,
tau_NL and a small g_NL. For certain parameter values we can satisfy
tau_NL>>f_NL^2. The bispectrum is of the local type but may have a significant
scale dependence. We show that the loop corrections to the power spectrum and
bispectrum are suppressed during inflation, if one assume that the fields
follow a classical background trajectory. We also include the effect of the
waterfall field, which can lead to a significant change in the observables
after the waterfall field is destabilised, depending on the couplings between
the waterfall and inflaton fields.Comment: 16 pages, 6 figures; v2: comments and references added, typos
corrected, matches published versio
Supergravity Inflation Free from Harmful Relics
We present a realistic supergravity inflation model which is free from the
overproduction of potentially dangerous relics in cosmology, namely moduli and
gravitinos which can lead to the inconsistencies with the predictions of baryon
asymmetry and nucleosynthesis. The radiative correction turns out to play a
crucial role in our analysis which raises the mass of supersymmetry breaking
field to intermediate scale. We pay a particular attention to the non-thermal
production of gravitinos using the non-minimal Kahler potential we obtained
from loop correction. This non-thermal gravitino production however is
diminished because of the relatively small scale of inflaton mass and small
amplitudes of hidden sector fields.Comment: 10 pages, revtex, 1 eps figure, references added, conclusion section
expande
Verbal working memory and functional large-scale networks in schizophrenia
The aim of this study was to test whether bilinear and nonlinear effective connectivity (EC) measures of working memory fMRI data can differentiate between patients with schizophrenia (SZ) and healthy controls (HC). We applied bilinear and nonlinear Dynamic Causal Modeling (DCM) for the analysis of verbal working memory in 16 SZ and 21 HC. The connection strengths with nonlinear modulation between the dorsolateral prefrontal cortex (DLPFC) and the ventral tegmental area/substantia nigra (VTA/SN) were evaluated. We used Bayesian Model Selection at the group and family levels to compare the optimal bilinear and nonlinear models. Bayesian Model Averaging was used to assess the connection strengths with nonlinear modulation. The DCM analyses revealed that SZ and HC used different bilinear networks despite comparable behavioral performance. In addition, the connection strengths with nonlinear modulation between the DLPFC and the VTA/SN area showed differences between SZ and HC. The adoption of different functional networks in SZ and HC indicated neurobiological alterations underlying working memory performance, including different connection strengths with nonlinear modulation between the DLPFC and the VTA/SN area. These novel findings may increase our understanding of connectivity in working memory in schizophrenia
Myristoylated CIL-7 regulates ciliary extracellular vesicle biogenesis
The cilium both releases and binds to extracellular vesicles (EVs). EVs may be used by cells as a form of intercellular communication and mediate a broad range of physiological and pathological processes. The mammalian polycystins (PCs) localize to cilia, as well as to urinary EVs released from renal epithelial cells. PC ciliary trafficking defects may be an underlying cause of autosomal dominant polycystic kidney disease (PKD), and ciliary–EV interactions have been proposed to play a central role in the biology of PKD. In Caenorhabditis elegans and mammals, PC1 and PC2 act in the same genetic pathway, act in a sensory capacity, localize to cilia, and are contained in secreted EVs, suggesting ancient conservation. However, the relationship between cilia and EVs and the mechanisms generating PC-containing EVs remain an enigma. In a forward genetic screen for regulators of C. elegans PKD-2 ciliary localization, we identified CIL-7, a myristoylated protein that regulates EV biogenesis. Loss of CIL-7 results in male mating behavioral defects, excessive accumulation of EVs in the lumen of the cephalic sensory organ, and failure to release PKD-2::GFP-containing EVs to the environment. Fatty acylation, such as myristoylation and palmitoylation, targets proteins to cilia and flagella. The CIL-7 myristoylation motif is essential for CIL-7 function and for targeting CIL-7 to EVs. C. elegans is a powerful model with which to study ciliary EV biogenesis in vivo and identify cis-targeting motifs such as myristoylation that are necessary for EV–cargo association and function
Spin relaxation in (110) and (001) InAs/GaSb superlattices
We report an enhancement of the electron spin relaxation time (T1) in a (110)
InAs/GaSb superlattice by more than an order of magnitude (25 times) relative
to the corresponding (001) structure. The spin dynamics were measured using
polarization sensitive pump probe techniques and a mid-infrared, subpicosecond
PPLN OPO. Longer T1 times in (110) superlattices are attributed to the
suppression of the native interface asymmetry and bulk inversion asymmetry
contributions to the precessional D'yakonov Perel spin relaxation process.
Calculations using a nonperturbative 14-band nanostructure model give good
agreement with experiment and indicate that possible structural inversion
asymmetry contributions to T1 associated with compositional mixing at the
superlattice interfaces may limit the observed spin lifetime in (110)
superlattices. Our findings have implications for potential spintronics
applications using InAs/GaSb heterostructures.Comment: 4 pages, 2 figure
The Middle Way: East Asian masters students’ perceptions of critical argumentation in U.K. universities.
The paper explores the learning experiences of East Asian masters students in dealing with Western academic norms of critical thinking in classroom debate and assignment writing. The research takes a cultural approach, and employs grounded theory and case study methodology, the aims being for students to explain their perceptions of their personal learning journeys. The data suggest that the majority of students interviewed rejected full academic acculturation into Western norms of argumentation. They instead opted for a ‘Middle Way’ that synergizes the traditional cultural academic values held by many East Asian students with those elements of Western academic norms that are perceived to be aligned with these. This is a relatively new area of research which represents a challenge for British lecturers and students
Inflationary Cosmology with Five Dimensional SO(10)
We discuss inflationary cosmology in a five dimensional SO(10) model
compactified on , which yields below the compactification scale. The gauge
symmetry is preserved on one of the fixed points, while
``flipped'' is on the other fixed point. Inflation is
associated with breaking, and is implemented through -term scalar
potentials on the two fixed points. A brane-localized Einstein-Hilbert term
allows both branes to have positive tensions during inflation. The scale of
breaking is fixed from measurements to be around
GeV, and the scalar spectral index . The inflaton field
decays into right-handed neutrinos whose subsequent out of equilibrium decay
yield the observed baryon asymmetry via leptogenesis.Comment: 1+19 pages, improved discussion of 5D cosmology, Version to appear in
PR
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