2,102 research outputs found
Warped Phenomenology
We explore the phenomenology associated with the recently proposed localized
gravity model of Randall and Sundrum where gravity propagates in a
5-dimensional non-factorizable geometry and generates the 4-dimensional
weak-Planck scale hierarchy by an exponential function of the compactification
radius, called a warp factor. The Kaluza-Klein tower of gravitons which emerge
in this scenario have strikingly different properties than in the factorizable
case with large extra dimensions. We derive the form of the graviton tower
interactions with the Standard Model fields and examine their direct production
in Drell-Yan and dijet events at the Tevatron and LHC as well as the KK
spectrum line-shape at high-energy linear \epem colliders. In the case where
the first KK excitation is observed, we outline the procedure to uniquely
determine the parameters of this scenario. We also investigate the effect of KK
tower exchanges in contact interaction searches. We find that present
experiments can place meaningful constraints on the parameters of this model.Comment: 14 pages, LaTex, 3 fig
Enniatin and Beauvericin Biosynthesis in Fusarium Species: Production Profiles and Structural Determinant Prediction
Citation: Liuzzi, V. C., Mirabelli, V., Cimmarusti, M. T., Haidukowski, M., Leslie, J. F., Logrieco, A. F., . . . Mule, G. (2017). Enniatin and Beauvericin Biosynthesis in Fusarium Species: Production Profiles and Structural Determinant Prediction. Toxins, 9(2), 17. doi:10.3390/toxins9020045Members of the fungal genus Fusarium can produce numerous secondary metabolites, including the nonribosomal mycotoxins beauvericin (BEA) and enniatins (ENNs). Both mycotoxins are synthesized by the multifunctional enzyme enniatin synthetase (ESYN1) that contains both peptide synthetase and S-adenosyl-L-methionine-dependent N-methyltransferase activities. Several Fusarium species can produce ENNs, BEA or both, but the mechanism(s) enabling these differential metabolic profiles is unknown. In this study, we analyzed the primary structure of ESYN1 by sequencing esyn1 transcripts from different Fusarium species. We measured ENNs and BEA production by ultra-performance liquid chromatography coupled with photodiode array and Acquity QDa mass detector (UPLC-PDA-QDa) analyses. We predicted protein structures, compared the predictions by multivariate analysis methods and found a striking correlation between BEA/ENN-producing profiles and ESYN1 three-dimensional structures. Structural differences in the beta strand's Asn789-Ala793 and His797-Asp802 portions of the amino acid adenylation domain can be used to distinguish BEA/ENN-producing Fusarium isolates from those that produce only ENN
Photons, neutrinos and large compact space dimensions
We compute the contribution of Kaluza-Klein graviton exchange to the cross
section for photon-neutrino scattering. Unlike the usual situation where the
virtual graviton exchange represents a small correction to a leading order
electroweak or strong amplitude, in this case the graviton contribution is of
the same order as the electroweak amplitude, or somewhat larger. Inclusion of
the graviton contribution is not sufficient to allow high energy neutrinos to
scatter from relic neutrinos in processes such as
, but the photon-neutrino decoupling temperature
is substantially reduced.Comment: 8 pages, 3 figures LaTeX. Typos correcte
A Large Mass Hierarchy from a Small Extra Dimension
We propose a new higher-dimensional mechanism for solving the Hierarchy
Problem. The Weak scale is generated from a large scale of order the Planck
scale through an exponential hierarchy. However, this exponential arises not
from gauge interactions but from the background metric (which is a slice of
AdS_5 spacetime). This mechanism relies on the existence of only a single
additional dimension. We demonstrate a simple explicit example of this
mechanism with two three-branes, one of which contains the Standard Model
fields. The experimental consequences of this scenario are new and dramatic.
There are fundamental spin-2 excitations with mass of weak scale order, which
are coupled with weak scale as opposed to gravitational strength to the
standard model particles. The phenomenology of these models is quite distinct
from that of large extra dimension scenarios; none of the current constraints
on theories with very large extra dimensions apply.Comment: 9 pages, LaTe
Gut mobilization improves behavioral symptoms and modulates urinary p-cresol in chronically constipated autistic children: A prospective study
Chronic constipation is common among children with ASD and is associated with more severe hyperactivity, anxiety, irritability, and repetitive behaviors. Young autistic children with chronic constipation display higher urinary, and foecal concentrations of p-cresol, an aromatic compound produced by gut bacteria, known to negatively affect brain function. Acute p-cresol administration to BTBR mice enhances anxiety, hyperactivity and stereotypic behaviors, while blunting social interaction. This study was undertaken to prospectively assess the behavioral effects of gut mobilization in young autistic children with chronic constipation, and to verify their possible correlation with urinary p-cresol. To this aim, 21 chronically constipated autistic children 2–8 years old were evaluated before (T0), 1 month (T1), and 6 months (T2) after intestinal mobilization, recording Bristol stool scale scores, urinary p-cresol concentrations, and behavioral scores for social interaction deficits, stereotypic behaviors, anxiety, and hyperactivity. Gut mobilization yielded a progressive and highly significant decrease in all behavioral symptoms over the 6-month study period. Urinary p-cresol levels displayed variable trends not significantly correlated with changes in behavioral parameters, mainly increasing at T1 and decreasing at T2. These results support gut mobilization as a simple strategy to ameliorate ASD symptoms, as well as comorbid anxiety and hyperactivity, in chronically constipated children. Variation in p-cresol absorption seemingly provides limited contributions, if any, to these behavioral changes. Further research will be needed to address the relative role of reduced abdominal discomfort following mobilization, as compared to specific modifications in microbiome composition and in gut bacteria-derived neuroactive compounds
Towards 5D Grand Unification without SUSY Flavor Problem
We consider the renormalization group approach to the SUSY flavor problem in
the supersymmetric SU(5) model with one extra dimension. In higher dimensional
SUSY gauge theories, it has been recently shown that power corrections due to
the Kaluza-Klein states of gauge fields run the soft masses generated at the
orbifold fixed point to flavor conserving values in the infra-red limit. In
models with GUT breaking at the brane where the GUT scale can be larger than
the compactification scale, we show that the addition of a bulk Higgs
multiplet, which is necessary for the successful unification, is compatible
with the flavor universality achieved at the compactification scale.Comment: JHEP style file of 35 pages with 3 figures, Version to appear in JHE
Brane fluctuations and suppression of Kaluza-Klein mode couplings
In higher dimensional models where the gauge and gravity fields live in the
bulk and the matter fields only in a brane, we point out the importance of the
brane (transverse) coordinate modes, which are the Nambu-Goldstone bosons
appearing as a result of spontaneous breaking of the translation symmetry. The
brane recoil effect suppresses the couplings of higher Kaluza-Klein modes to
the matter, and gives a natural resolution to the divergence problem caused by
the exchange of infinitely many Kaluza-Klein modes.Comment: 11 pages, 1 eps figure, references adde
Universality limits on bulk fermions
The Kaluza-Klein fermion excitations induce mixing between the Standard Model
fermions and loss of universality. The flavour mixing not present in the
Standard Model can be made to vanish aligning the Yukawa couplings and the
Dirac masses of the heavy modes, but universality is only recovered when these
masses go to infinity. This implies a bound on the lightest new heavy quark, M1
\~ 3-5 TeV, which together with the electroweak precision data limits will
allow the Large Hadron Collider to provide a crucial test of the
Randall-Sundrum ansatz for solving the gauge hierarchy.Comment: 12 pages, 1 figure, few typos corrected, reference added, version to
appear in PL
Supersymmetric Brane World Scenarios from Off-Shell Supergravity
Using N=2 off-shell supergravity in five dimensions, we supersymmetrize the
brane world scenario of Randall and Sundrum. We extend their construction to
include supersymmetric matter at the fixpoints.Comment: 15 pages, no figures, late
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