194 research outputs found
The New Zealand Kauri (Agathis Australis) Research Project: A Radiocarbon Dating Intercomparison of Younger Dryas Wood and Implications for IntCal13
We describe here the New Zealand kauri (Agathis australis) Younger Dryas (YD) research project, which aims to undertake Î14C analysis of ~140 decadal floating wood samples spanning the time interval ~13.1â11.7 kyr cal BP. We report 14C intercomparison measurements being undertaken by the carbon dating laboratories at University of Waikato (Wk), University of California at Irvine (UCI), and University of Oxford (OxA). The Wk, UCI, and OxA laboratories show very good agreement with an interlaboratory comparison of 12 successive decadal kauri samples (average offsets from consensus values of â7 to +4 14C yr). A University of Waikato/University of Heidelberg (HD) intercomparison involving measurement of the YD-age Swiss larch tree Ollon505, shows a HD/Wk offset of ~10â20 14C yr (HD younger), and strong evidence that the positioning of the Ollon505 series is incorrect, with a recommendation that the 14C analyses be removed from the IntCal calibration database
SmartRegio â Employing Spatial Data to Provide Decision Support for SMEs and City Administrations
When decisions have to be made which are based on the characteristics and expected developments in
specific spatial environments (such as finding the best place for a new production site or for a new shop), geo
data and the information that can be derived from it plays a crucial role. While larger companies typically
can afford the setup of the required organisational units as well as the access to relevant data from
commercial providers, smaller organisations such as SMEs or city administrations are at a disadvantage. The
aim of the SmartRegio project was to develop solutions for such organisations that combine freely available
(mass) spatial data from many different sources as a decision-making basis focusing on governmental and
private actors operating with a focus on a specific region. The data sources include data from infrastructures
like energy and mobility, data from public entities, and also data from social media and media channels. The
SmartRegio project successfully identified and tackled major technical and legal challenges when aiming to
exploit such data, while at the same time realising a generic infrastructure that supports the required
processes within the given context
Decadally resolved lateglacial radiocarbon evidence from New Zealand kauri
Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Arizona Board of Regents on behalf of the University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 58 (2016): 709-733, doi: 10.1017/RDC.2016.86.The Last Glacial-Interglacial Transition (LGIT; 15,000-11,000 cal BP) was
characterized by complex spatiotemporal patterns of climate change, with
numerous studies requiring accurate chronological control to decipher leads
from lags in global paleoclimatic, -environmental and archaeological records.
However, close scrutiny of the few available tree-ring chronologies and 14C-dated
sequences composing the IntCal13 radiocarbon calibration curve, indicates
significant weakness in 14C calibration across key periods of the LGIT. Here, we
present a decadally-resolved atmospheric 14C record derived from New Zealand
kauri spanning the Lateglacial from ~13,100 - 11,365 cal BP. Two floating kauri
14C time series, curve-matched to IntCal13, serve as a radiocarbon backbone
through the Younger Dryas. The floating Northern Hemisphere (NH) 14C datasets
derived from the YD-B and Central European Lateglacial Master tree-ring series
are matched against the new kauri data, forming a robust NH 14C time series to
~14,200 cal BP. Our results show that IntCal13 is questionable from ~12,200 -
11,900 cal BP and the ~10,400 BP 14C plateau is approximately five decades too short. The new kauri record and re-positioned NH pine 14C series offer a
refinement of the international 14C calibration curves IntCal13 and SHCal13,
providing increased confidence in the correlation of global paleorecords.This work was part funded by the Foundation for
Research, Science and Technology (FRST)ânow Ministry for Business,
Innovation & Employment (MBIE)-PROP-20224-SFK-UOA), a Royal Society of
New Zealand grant, the Australian Research Council (FL100100195 and
DP0664898) and the Natural Environment Research Council (NE/H009922/1,
NE/I007660/1, NER/A/S/2001/01037 and NE/H007865/1)
The Lyth Bound and the End of Inflation
We derive an extended version of the well-known Lyth Bound on the total
variation of the inflaton field, incorporating higher order corrections in slow
roll. We connect the field variation to both the spectral index of
scalar perturbations and the amplitude of tensor modes. We then investigate the
implications of this bound for ``small field'' potentials, where the field
rolls off a local maximum of the potential. The total field variation during
inflation is {\em generically} of order , even for potentials with
a suppressed tensor/scalar ratio. Much of the total field excursion arises in
the last e-fold of inflation and in single field models this problem can only
be avoided via fine-tuning or the imposition of a symmetry. Finally, we discuss
the implications of this result for inflationary model building in string
theory and supergravity.Comment: 10 pages, RevTeX, 2 figures (V3: version accepted for publication by
JCAP
Cosmology From Random Multifield Potentials
We consider the statistical properties of vacua and inflationary trajectories
associated with a random multifield potential. Our underlying motivation is the
string landscape, but our calculations apply to general potentials. Using
random matrix theory, we analyze the Hessian matrices associated with the
extrema of this potential. These potentials generically have a vast number of
extrema. If the cross-couplings (off-diagonal terms) are of the same order as
the self-couplings (diagonal terms) we show that essentially all extrema are
saddles, and the number of minima is effectively zero. Avoiding this requires
the same separation of scales needed to ensure that Newton's constant is stable
against radiative corrections in a string landscape. Using the central limit
theorem we find that even if the number of extrema is enormous, the typical
distance between extrema is still substantial -- with challenging implications
for inflationary models that depend on the existence of a complicated path
inside the landscape.Comment: revtex, 3 figures, 10 pages v2 refs adde
Simplified Models for LHC New Physics Searches
This document proposes a collection of simplified models relevant to the
design of new-physics searches at the LHC and the characterization of their
results. Both ATLAS and CMS have already presented some results in terms of
simplified models, and we encourage them to continue and expand this effort,
which supplements both signature-based results and benchmark model
interpretations. A simplified model is defined by an effective Lagrangian
describing the interactions of a small number of new particles. Simplified
models can equally well be described by a small number of masses and
cross-sections. These parameters are directly related to collider physics
observables, making simplified models a particularly effective framework for
evaluating searches and a useful starting point for characterizing positive
signals of new physics. This document serves as an official summary of the
results from the "Topologies for Early LHC Searches" workshop, held at SLAC in
September of 2010, the purpose of which was to develop a set of representative
models that can be used to cover all relevant phase space in experimental
searches. Particular emphasis is placed on searches relevant for the first
~50-500 pb-1 of data and those motivated by supersymmetric models. This note
largely summarizes material posted at http://lhcnewphysics.org/, which includes
simplified model definitions, Monte Carlo material, and supporting contacts
within the theory community. We also comment on future developments that may be
useful as more data is gathered and analyzed by the experiments.Comment: 40 pages, 2 figures. This document is the official summary of results
from "Topologies for Early LHC Searches" workshop (SLAC, September 2010).
Supplementary material can be found at http://lhcnewphysics.or
Widespread Treponema pallidum Infection in Nonhuman Primates, Tanzania
We investigated Treponema pallidum infection in 8 nonhuman primate species (289 animals) in Tanzania during 2015â2017. We used a serologic treponemal test to detect antibodies against the bacterium. Infection was further confirmed from tissue samples of skin-ulcerated animals by 3 independent PCRs (polA, tp47, and TP_0619). Our findings indicate that T. pallidum infection is geographically widespread in Tanzania and occurs in several species (olive baboons, yellow baboons, vervet monkeys, and blue monkeys). We found the bacterium at 11 of 14 investigated geographic locations. Anogenital ulceration was the most common clinical manifestation; orofacial lesions also were observed. Molecular data show that nonhuman primates in Tanzania are most likely infected with T. pallidum subsp. pertenueâlike strains, which could have implications for human yaws eradication
Punctuated shutdown of Atlantic Meridional Overturning circulation during Greenland Stadial 1
The Greenland Stadial 1 (GS-1; ~12.9 to 11.65 kyr cal BP) was a period of North Atlantic cooling, thought to have been initiated by North America fresh water runof that caused a sustained reduction of North Atlantic Meridional Overturning Circulation (AMOC), resulting in an antiphase temperature response between the hemispheres (the âbipolar seesawâ). Here we exploit sub-fossil New Zealand kauri trees to report the frst securely dated, decadally-resolved atmospheric radiocarbon (ÂčâŽC) record spanning GS-1. By precisely aligning Southern and Northern Hemisphere tree-ring ÂčâŽC records with marine ÂčâŽC sequences we document two relatively short periods of AMOC collapse during the stadial, at ~12,920-12,640 cal BP and 12,050-11,900 cal BP. In addition, our data show that the interhemispheric atmospheric ÂčâŽC ofset was close to zero prior to GS-1, before reaching ânear-modernâ values at ~12,660 cal BP, consistent with synchronous recovery of overturning in both hemispheres and increased Southern Ocean ventilation. Hence, sustained North Atlantic cooling across GS-1 was not driven by a prolonged AMOC reduction but probably due to an equatorward migration of the Polar Front, reducing the advection of southwesterly air masses to high latitudes. Our fndings suggest opposing hemispheric temperature trends were driven by atmospheric teleconnections, rather than AMOC changes
- âŠ