88 research outputs found
Small Scattered Fragments Do Not a Dwarf Make: Biological and Archaeological Data Indicate that Prehistoric Inhabitants of Palau Were Normal Sized
Current archaeological evidence from Palau in western Micronesia indicates that the archipelago was settled around 3000â3300 BP by normal sized populations; contrary to recent claims, they did not succumb to insular dwarfism
Long-interval intracortical inhibition as biomarker for epilepsy: a transcranial magnetic stimulation study
Cortical excitability, as measured by transcranial magnetic stimulation combined with electromyography, is a potential biomarker for the diagnosis and follow-up of epilepsy. We report on long-interval intracortical inhibition data measured in four different centres in healthy controls (n = 95), subjects with refractory genetic generalized epilepsy (n = 40) and with refractory focal epilepsy (n = 69). Long-interval intracortical inhibition was measured by applying two supra-threshold stimuli with an interstimulus interval of 50, 100, 150, 200 and 250 ms and calculating the ratio between the response to the second (test stimulus) and to the first (conditioning stimulus). In all subjects, the median response ratio showed inhibition at all interstimulus intervals. Using a mixed linear-effects model, we compared the long-interval intracortical inhibition response ratios between the different subject types. We conducted two analyses; one including data from the four centres and one excluding data from Centre 2, as the methods in this centre differed from the others. In the first analysis, we found no differences in long-interval intracortical inhibition between the different subject types. In all subjects, the response ratios at interstimulus intervals 100 and 150 ms showed significantly more inhibition than the response ratios at 50, 200 and 250 ms. Our second analysis showed a significant interaction between interstimulus interval and subject type (P = 0.0003). Post hoc testing showed significant differences between controls and refractory focal epilepsy at interstimulus intervals of 100 ms (P = 0.02) and 200 ms (P = 0.04). There were no significant differences between controls and refractory generalized epilepsy groups or between the refractory generalized and focal epilepsy groups. Our results do not support the body of previous work that suggests that long-interval intracortical inhibition is significantly reduced in refractory focal and genetic generalized epilepsy. Results from the second analysis are even in sharper contrast with previous work, showing inhibition in refractory focal epilepsy at 200 ms instead of facilitation previously reported. Methodological differences, especially shorter intervals between the pulse pairs, may have contributed to our inability to reproduce previous findings. Based on our results, we suggest that long-interval intracortical inhibition as measured by transcranial magnetic stimulation and electromyography is unlikely to have clinical use as a biomarker of epilepsy
Arc magmas sourced from melange diapirs in subduction zones
Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Geoscience 5 (2012): 862-867, doi:10.1038/ngeo1634.At subduction zones, crustal material is recycled back into the mantle. A certain proportion, however, is returned to the overriding
plate via magmatism. The magmas show a characteristic range of compositions that have been explained by three-component
mixing in their source regions: hydrous fluids derived from subducted altered oceanic crust and components derived from the thin
sedimentary veneer are added to the depleted peridotite in the mantle beneath the volcanoes. However, currently no uniformly
accepted model exists for the physical mechanism that mixes the three components and transports them from the slab to the
magma source.
Here we present an integrated physico-chemical model of subduction zones that emerges from a review of the combined findings
of petrology, modelling, geophysics, and geochemistry: Intensely mixed metamorphic rock formations, so-called mélanges, form
along the slab-mantle interface and comprise the characteristic trace-element patterns of subduction-zone magmatic rocks. We
consider mélange formation the physical mixing process that is responsible for the geochemical three-component pattern of the
magmas. Blobs of low-density mélange material, so-called diapirs, rise buoyantly from the surface of the subducting slab and
provide a means of transport for well-mixed materials into the mantle beneath the volcanoes, where they produce melt. Our model
provides a consistent framework for the interpretation of geophysical, petrological and geochemical data of subduction zones.H.M. was funded
by the J. LamarWorzel Assistant Scientist Fund and the
Penzance Endowed Fund in Support of Assistant Scientists.
Funding from NSF grant #1119403 (G. Harlow)
is acknowledged.2013-05-1
Luminescence characteristics of quartz from Brazilian sediments and constraints for OSL dating
This study analyzes the optically stimulated luminescence (OSL) characteristics of quartz grains from fluvial, eolian and shallow marine sands of northeastern and southeastern Brazil, with especial focus on the applicability of the single-aliquot regenerative dose (SAR) dating protocol. All analyzed Brazilian sediments presented relatively high OSL sensitivity and good behavior regarding their luminescence characteristics relevant for radiation dose estimation. However, some samples from the LençĂÂłis Maranhenses region in northeastern Brazil showed inadequate OSL sensitivity correction, hampering the implementation of the SAR protocol and their ability to behave as a natural dosimeter. While the shallow marine and eolian samples showed a narrow and reliable dose distribution, the fluvial sample had a wide dose distribution, suggesting incomplete bleaching and natural doses estimates dependent on age models
Why Rice Farmers Don't Sail: Coastal Subsistence Traditions and Maritime Trends in Early China
The Lower Yangtze River Valley is a key region for the early development of rice farming and the emergence of wet rice paddy field systems. Subsistence evidence from Neolithic sites in this area highlights the importance of freshwater wetlands for both plant and animal food resources. Early Neolithic rice cultivators looked inland, especially to wetlands and nearby woodlands, for their main protein sources. Links to the sea among these Neolithic populations are notably scarce. Due to the high yields of wet rice, compared with other staple crops as well as dryland rice, the wetland rice focused subsistence strategy of the Lower Yangtze would have supported high, and increasing, local population densities. Paddy agriculture demands labor input and water management on a large scale, which would have stimulated and reinforced trends towards more complex societies, such as that represented by Liangzhu in the lower Yangtze region. Population growth could have been largely absorbed locally, suggesting that population packing, not migration, was the dominant trend. Other case studies of agricultural dispersal, for the Korean Peninsula and Japan further illustrate the lack of correlation between the spread of rice agriculture and wet rice cultivation. Although wet rice cultivation was a pull factor that drew local populations towards increased density and increased social complexity, it did not apparently push groups to migrate outwards. Instead, the transition from wetland to rain fed rice cultivation systems and/or the integration of rice with rain fed millet crops are much more likely to have driven the demographic dynamics that underpin early farmer migrations and crop dispersal
Observation of a resonant structure near the threshold in the decay
An amplitude analysis of the decay is carried out to
study for the first time its intermediate resonant contributions, using
proton-proton collision data collected with the LHCb detector at centre-of-mass
energies of 7, 8 and 13 TeV. A near-threshold peaking structure, referred to as
, is observed in the invariant-mass spectrum with
significance greater than 12 standard deviations. The mass, width and the
quantum numbers of the structure are measured to be MeV,
MeV and , respectively, where the first
uncertainties are statistical and the second systematic. The properties of the
new structure are consistent with recent theoretical predictions for a state
composed of quarks. Evidence for an additional structure is
found around 4140 MeV in the invariant mass, which might be
caused either by a new resonance with the assignment or by a coupled-channel effect.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-018.html (LHCb
public pages
Measurement of the ratios of branching fractions R(D*) and R(D0)
The ratios of branching fractions
R
(
D
â
)
âĄ
B
(
ÂŻ
B
â
D
â
Ï
â
ÂŻ
Μ
Ï
)
/
B
(
ÂŻ
B
â
D
â
Ό
â
ÂŻ
Μ
Ό
)
and
R
(
D
0
)
âĄ
B
(
B
â
â
D
0
Ï
â
ÂŻ
Μ
Ï
)
/
B
(
B
â
â
D
0
Ό
â
ÂŻ
Μ
Ό
)
are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to
3.0
â
â
fb
â
1
of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode
Ï
â
â
Ό
â
Μ
Ï
ÂŻ
Μ
Ό
. The measured values are
R
(
D
â
)
=
0.281
±
0.018
±
0.024
and
R
(
D
0
)
=
0.441
±
0.060
±
0.066
, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is
Ï
=
â
0.43
. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model
Measurement of antiproton production from antihyperon decays in p He collisions at âsNN = 110 GeV
The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5TeV incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and 110GeV. The dominant antihyperon contribution, namely ÎÂŻâpÂŻÏ+ decays from promptly produced ÎÂŻ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models
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