573 research outputs found
Six-dimensional superconformal couplings of non-abelian tensor and hypermultiplets
We construct six-dimensional superconformal models with non-abelian tensor
and hypermultiplets. They describe the field content of (2,0) theories, coupled
to (1,0) vector multiplets. The latter are part of the non-abelian gauge
structure that also includes non-dynamical three- and four-forms. The
hypermultiplets are described by gauged nonlinear sigma models with a
hyper-Kaehler cone target space. We also address the question of constraints in
these models and show that their resolution requires the inclusion of abelian
factors. These provide couplings that were previously considered for anomaly
cancellations with abelian tensor multiplets and resulted in the selection of
ADE gauge groups.Comment: 25 page
New developments in the quantization of supersymmetric solitons (kinks, vortices and monopoles)
We discuss the one-loop quantum corrections to the mass M and central charge
Z of supersymmetric solitons: the kink, the vortex and the monopole. Contrary
to previous expectations and published results, in each of these cases there
are nonvanishing quantum corrections to the mass. For the N=1 kink and the N=2
monopole a new anomaly in Z rescues BPS saturation (M=Z); for the N=2 vortex,
BPS saturation is rescued for two reasons: (i) the quantum fluctuations of the
Higgs field acquire a nontrivial phase due to the winding of the classical
solution, and (ii) a fermionic zero mode used in the literature is shown not to
be normalizable.Comment: 15 pages, REVTEX4 style, 1 embedded postscript figure. Extended
writeup of a talk given by P. van Nieuwenhuizen at the XXIV Brazilian
National Meeting on Particles and Fields (Caxambu, Brazil, 30 Sep - 4 Oct
2003); to appear in the Brazilian Journal of Physic
Early Indicators of Later Work Levels, Disease, and Death
This paper summarizes a collaborative project designed to create a public-use tape suitable for a prospective study of aging among a random sample of 39,616 men mustered into 331 companies of the Union Army. The aim of the project is to measure the effect of socioeconomics and biomedical factors during childhood and early adulthood on the development of specific chronic disease at middle and late ages, on labor force participation at these later ages, and on elapsed time to death. This paper surveys the nature of and quality of the data and data sources to be included in the study, discusses the characteristics of a subsample of recruits from 20 companies recently recruited, looks at questions of representativeness of Union Army recruits to the Northern white male population, and finally examines several issues involving questions of possible selection bias due to linkage failure.
Disparity among low first ionization potential elements
The elemental composition of the solar wind differs from the solar
photospheric composition. Elements with low first ionization potential (FIP)
appear enhanced compared to O in the solar wind relative to the respective
photospheric abundances. This so-called FIP effect is different in the slow
solar wind and the coronal hole wind. However, under the same plasma
conditions, for elements with similar FIPs such as Mg, Si, and Fe, comparable
enhancements are expected. We scrutinize the assumption that the FIP effect is
always similar for different low FIP elements, namely Mg, Si, and Fe. We
investigate the dependency of the FIP effect of low FIP elements on the O7+/O6+
charge state ratio depending on time and solar wind type. We order the observed
FIP ratios with respect to the O7+/O6+ charge state ratio into bins and analyze
separately the respective distributions of the FIP ratio of Mg, Si, and Fe for
each O7+/O6+ charge state ratio bin. We observe that the FIP effect shows the
same qualitative yearly behavior for Mg and Si, while Fe shows significant
differences during the solar activity maximum and its declining phase. In each
year, the FIP effect for Mg and Si always increases with increasing O7+/O6+
charge state ratio, but for high O7+/O6+ charge state ratios the FIP effect for
Fe shows a qualitatively different behavior. During the years 2001-2006,
instead of increasing with the O7+/O6+ charge state ratio, the Fe FIP ratio
exhibits a broad peak. Also, the FIP distribution per O7+/O6+ charge state bin
is significantly broader for Fe than for Mg and Si. These observations support
the conclusion that the elemental fractionation is only partly determined by
FIP. In particular, the qualitative difference behavior with increasing O7+/O6+
charge state ratio between Fe on the one hand and Mg and Si on the other hand
is not yet well explained by models of fractionation
N=6 Superspace Constraints, SUSY Enhancement and Monopole Operators
International audienceWe present a systematic analysis of the N=6 superspace constraints in three space-time dimensions. The general coupling between vector and scalar supermultiplets is encoded in an SU(4) tensor which is a function of the matter fields and subject to a set of algebraic and super-differential relations. We give a genuine N=6 classification for superconformal models with polynomial interactions and find the known ABJM and ABJ models. We further study the issue of supersymmetry enhancement to N=8 and the role of monopole operators in this scenario. To this end we assume the existence of a composite monopole operator superfield which we use to formulate the additional supersymmetries as internal symmetries of the N=6 superspace constraints. From the invariance conditions of these constraints we derive a system of superspace constraints for the proposed monopole operator superfield. This constraint system defines the composite monopole operator superfield analogously to the original N=6 superspace constraints defining the dynamics of the elementary fields
Quantum corrections to mass and central charge of supersymmetric solitons
We review some recent developments in the subject of quantum corrections to
soliton mass and central charge. We consider in particular approaches which use
local densities for these corrections, as first discussed by Hidenaga
Yamagishi. We then consider dimensional regularization of the supersymmetric
kink in 1+1 dimensions and an extension of this method to a 2+1-dimensional
gauge theory with supersymmetric abelian Higgs vortices as the solitons.Comment: 41 pages. Contribution to the Hidenaga Yamagishi commemorative volume
of Physics Reports, edited by E. Witten and I. Zahe
FDG PET in Thyroid Cancer
Thyroid malignancies are relatively rare cancer types but have a substantially high incidence in the group of all endocrine malignancies. Most thyroid cancer patients have differentiated thyroid cancer and prognosis is generally favourable. Tumour growth tends to be slow and radioiodine therapy is successful in differentiated cell tumour type with the ability to accumulate iodine. So, where can 18F-fluorodeoxyglucose positron emission tomography (FDG PET) imaging be applied? The role of FDG PET in differentiated thyroid cancer starts with the development of metastatic diseases, which are not responsive to radioiodine therapy anymore. FDG accumulates in tumour lesions that are missed by iodine scintigraphy. FDG PET is more sensitive in patients with an aggressive histological subtype, including HĂĽrthle cell. Thyroid cancer is definitely not the role model indication for FDG PET imaging, but for the management of differentiated thyroid cancer with metastases and more aggressive types of malignancies of the thyroid, FDG PET proves to be clinically useful. Incidental detection of malignancy in FDG-avid thyroid nodules has to be taken into consideration when FDG PET examinations have been conducted for reasons unrelated to the thyroid
Evolution of an equatorial coronal hole structure and the released coronal hole wind stream: Carrington rotations 2039 to 2050
The Sun is a highly dynamic environment that exhibits dynamic behavior on
many different timescales. In particular, coronal holes exhibit temporal and
spatial variability. Signatures of these coronal dynamics are inherited by the
coronal hole wind streams that originate in these regions and can effect the
Earth's magnetosphere. Both the cause of the observed variabilities and how
these translate to fluctuations in the in situ observed solar wind is not yet
fully understood. During solar activity minimum the structure of the magnetic
field typically remains stable over several Carrington rotations (CRs). But how
stable is the solar magnetic field? Here, we address this question by analyzing
the evolution of a coronal hole structure and the corresponding coronal hole
wind stream emitted from this source region over 12 consecutive CRs in 2006. To
this end, we link in situ observations of Solar Wind Ion Composition
Spectrometer (SWICS) onboard the Advanced Composition Explorer (ACE) with
synoptic maps of Michelson Doppler imager (MDI) on the Solar and Heliospheric
Observatory (SOHO) at the photospheric level through a combination of ballistic
back-mapping and a potential field source surface (PFSS) approach. Together,
these track the evolution of the open field line region that is identified as
the source region of a recurring coronal hole wind stream.
We find that the shape of the open field line region and to some extent also
the solar wind properties are influenced by surrounding more dynamic closed
loop regions. We show that the freeze-in order can change within a coronal hole
wind stream on small timescales and illustrate a mechanism that can cause
changes in the freeze-in order. The inferred minimal temperature profile is
variable even within coronal hole wind and is in particular most variable in
the outer corona
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