1,238 research outputs found
Radiocarbon Dating Caribou Antler and Bone : Are They Different?
Old archaeological radiocarbon dating lore has it that caribou antler and bone give different dating results, and that for some fundamental reason antler is unreliable as a dating material. We tested this idea by measuring radiocarbon concentrations in the bone and antler of two caribou (one recent, one ancient) for which the antler was still attached to the cranium. No significant differences were found. Thus, it seems that this old myth is groundless.Selon de vieux dires, la radiodatation archéologique des bois et des os du renne donnerait des résultats différents et, pour une raison fondamentale, les bois ne représenteraient pas un matériau fiable pour la radiodatation. On a testé cette idée en mesurant les concentrations de radiocarbone dans les os et les bois de deux rennes (l'un mort récemment, l'autre il y a longtemps), où les bois étaient encore rattachés au crâne. On n'a pas trouvé de différence notable, ce qui semblerait signifier que l'ancien mythe est sans fondement
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PUREX new substation ATR
This document is the acceptance test report (ATR) for the New PUREX Main and Minisubstations. It covers the factory and vendor acceptance and commissioning test reports. Reports are presented for the Main 5 kV substation building, the building fire system, switchgear, and vacuum breaker; the minisubstation control building and switch gear; commissioning test; electrical system and loads inspection; electrical utilities transformer and cable; and relay setting changes based on operational experience
PRS9 Symptom Response Profiles For Patients With Chronic Obstructive Pulmonary Disease Initiating Nebulized Arformoterol Tartrate Or Placebo
Brane World Susy Breaking from String/M Theory
String and M-theory realizations of brane world supersymmetry breaking
scenarios are considered in which visible sector Standard Model fields are
confined on a brane, with hidden sector supersymmetry breaking isolated on a
distant brane. In calculable examples with an internal manifold of any volume
the Kahler potential generically contains brane--brane non-derivative contact
interactions coupling the visible and hidden sectors and is not of the no-scale
sequestered form. This leads to non-universal scalar masses and without
additional assumptions about flavor symmetries may in general induce dangerous
sflavor violation even though the Standard Model and supersymmetry branes are
physically separated. Deviations from the sequestered form are dictated by bulk
supersymmetry and can in most cases be understood as arising from exchange of
bulk supergravity fields between branes or warping of the internal geometry.
Unacceptable visible sector tree-level tachyons arise in many models but may be
avoided in certain classes of compactifications. Anomaly mediated and gaugino
mediated contributions to scalar masses are sub-dominant except in special
circumstances such as a flat or AdS pure five--dimensional bulk geometry
without bulk vector multiplets.Comment: Latex, 83 pages, references adde
The mass insertion approximation without squark degeneracy
We study the applicability of the mass insertion approximation (MIA) for
calculations of neutral meson mixing when squark masses are not degenerate and,
in particular, in models of alignment. We show that the MIA can give results
that are much better than an order of magnitude estimate as long as the masses
are not strongly hierarchical. We argue that, in an effective two-squark
framework, m_q=(m_1+m_2)/2 is the best choice for the MIA expansion point,
rather than, for example, m_q^2=(m_1^2+m_2^2)/2.Comment: 7 pages, revtex
Development of a sheep platform and behavioral monitoring methods for assessing deep brain stimulation therapies and devices for movement disorders
Preclinical animal models are essential for successful development of safe and effective commercialized CNS therapies. Objective data from animal models establish proof of concept evidence and provide critical inputs to the design of later phase clinical studies. In medical device development, a large animal with an intact nervous system is preferred because it permits use of human-scaled devices and controlled testing that cannot be replicated with computer modeling or bench-testing. Therefore, we established an in-house sheep platform for early-phase testing of deep brain stimulation (DBS) therapy concepts and devices within the movement disorders space. In twelve animals commercial DBS leads with four active contacts were targeted to the subthalamic nucleus (STN), a common stimulation target in Parkinson disease. Overall, DBS lead implantation was not associated with remarkable neurological or histopathological complications. Assessments of targeting using standard comparisons of pre and post-operative brain images indicated that accuracy was comparable to clinical experience. Methods were developed to quantitatively assess motor behavior of chronically-implanted animals in the awake state. In open and blinded settings, we consistently found that motor behavior responses to STN stimulation significantly depended on the stimulation contact selected and parameters tested, including voltage, pulse width and frequency. Quantitative electromyographic assessments confirmed the motor behavior findings. This work establishes in-house capabilities for controlled testing of emerging DBS therapy concepts and device prototypes. Further work is ongoing to test prototype devices and develop additional objective physiological monitoring methods and biomarkers
A Composite Little Higgs Model
We describe a natural UV complete theory with a composite little Higgs. Below
a TeV we have the minimal Standard Model with a light Higgs, and an extra
neutral scalar. At the TeV scale there are additional scalars, gauge bosons,
and vector-like charge 2/3 quarks, whose couplings to the Higgs greatly reduce
the UV sensitivity of the Higgs potential. Stabilization of the Higgs mass
squared parameter, without finetuning, occurs due to a softly broken shift
symmetry--the Higgs is a pseudo Nambu-Goldstone boson. Above the 10 TeV scale
the theory has new strongly coupled interactions. A perturbatively
renormalizable UV completion, with softly broken supersymmetry at 10 TeV is
explicitly worked out. Our theory contains new particles which are odd under an
exact "dark matter parity", (-1)^{(2S+3B+L)}. We argue that such a parity is
likely to be a feature of many theories of new TeV scale physics. The lightest
parity odd particle, or "LPOP", is most likely a neutral fermion, and may make
a good dark matter candidate, with similar experimental signatures to the
neutralino of the MSSM. We give a general effective field theory analysis of
the calculation of corrections to precision electroweak observables.Comment: 28 page
Can multi-TeV (top and other) squarks be natural in gauge mediation?
We investigate whether multi-TeV (1-3 TeV) squarks can be natural in models
of gauge mediated SUSY breaking. The idea is that for some boundary condition
of the scalar (Higgs and stop) masses, the Higgs (mass), evaluated at the
renormalization scale GeV, is not very sensitive to (boundary
values of) the scalar masses (this has been called ``focussing'' in recent
literature). Then, the stop masses can be multi-TeV without leading to
fine-tuning in electroweak symmetry breaking. {\em Minimal} gauge mediation
does {\em not} lead to this focussing (for all values of and the
messenger scale): the (boundary value of) the Higgs mass is too small compared
to the stop masses. Also, in minimal gauge mediation, the gaugino masses are of
the same order as the scalar masses so that multi-TeV scalars implies multi-TeV
gauginos (especially gluino) leading to fine-tuning. We discuss ideas to {\em
increase} the Higgs mass relative to the stop masses (so that focussing can be
achieved) and also to {\em suppress} gaugino masses relative to scalar masses
(or to modify the gaugino mass relations) in {\em non-minimal} models of gauge
mediation -- then multi-TeV (top and other) squarks can be natural. Specific
models of gauge mediation which incorporate these ideas and thus have squarks
(and in some cases, the gluino) heavier than a TeV without resulting in
fine-tuning are also studied and their collider signals are contrasted with
those of other models which have multi-TeV squarks.Comment: LaTeX, 29 pages, 9 eps figures. Replacing an earlier version. In
version 3, some references and a minor comment have been added and typos have
been correcte
Virus shapes and buckling transitions in spherical shells
We show that the icosahedral packings of protein capsomeres proposed by
Caspar and Klug for spherical viruses become unstable to faceting for
sufficiently large virus size, in analogy with the buckling instability of
disclinations in two-dimensional crystals. Our model, based on the nonlinear
physics of thin elastic shells, produces excellent one parameter fits in real
space to the full three-dimensional shape of large spherical viruses. The
faceted shape depends only on the dimensionless Foppl-von Karman number
\gamma=YR^2/\kappa, where Y is the two-dimensional Young's modulus of the
protein shell, \kappa is its bending rigidity and R is the mean virus radius.
The shape can be parameterized more quantitatively in terms of a spherical
harmonic expansion. We also investigate elastic shell theory for extremely
large \gamma, 10^3 < \gamma < 10^8, and find results applicable to icosahedral
shapes of large vesicles studied with freeze fracture and electron microscopy.Comment: 11 pages, 12 figure
A "Littlest Higgs" Model with Custodial SU(2) Symmetry
In this note, a ``littlest higgs'' model is presented which has an
approximate custodial SU(2) symmetry. The model is based on the coset space
. The light pseudo-goldstone bosons of the theory
include a {\it single} higgs doublet below a TeV and a set of three
triplets and an electroweak singlet in the TeV range. All of these scalars
obtain approximately custodial SU(2) preserving vacuum expectation values. This
model addresses a defect in the earlier moose
model, with the only extra complication being an extended top sector. Some of
the precision electroweak observables are computed and do not deviate
appreciably from Standard Model predictions. In an S-T oblique analysis, the
dominant non-Standard Model contributions are the extended top sector and higgs
doublet contributions. In conclusion, a wide range of higgs masses is allowed
in a large region of parameter space consistent with naturalness, where large
higgs masses requires some mild custodial SU(2) violation from the extended top
sector.Comment: 22 pages + 8 figures; JHEP style, added references and extra
discussion on size of T contributions, as well as some other minor
clarifications. Version to appear in JHE
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