28 research outputs found
Multi-field inflation with large scalar fluctuations: non-Gaussianity and perturbativity
Recently multi-field inflation models that can produce large scalar
fluctuations on small scales have drawn a lot of attention, primarily because
they could lead to primordial black hole production and generation of large
second-order gravitational waves. In this work, we focus on models where the
scalar fields responsible for inflation live on a hyperbolic field space. In
this case, geometrical destabilisation and non-geodesic motion are responsible
for the peak in the scalar power spectrum. We present new results for scalar
non-Gaussianity and discuss its dependence on the model's parameters. On scales
around the peak, we typically find that the non-Gaussianity is large and close
to local in form. We validate our results by employing two different numerical
techniques, utilising the transport approach, based on full cosmological
perturbation theory, and the formalism, based on the separate
universe approximation. We discuss implications of our results for the
perturbativity of the underlying theory, focusing in particular on versions of
these models with potentially relevant phenomenology at interferometer scales.Comment: version accepted for publication in JCA
Simplified path integral for supersymmetric quantum mechanics and type-A trace anomalies
Particles in a curved space are classically described by a nonlinear sigma model action that can be quantized through path integrals. The latter require a precise regularization to deal with the derivative interactions arising from the nonlinear kinetic term. Recently, for maximally symmetric spaces, simplified path integrals have been developed: they allow to trade the nonlinear kinetic term with a purely quadratic kinetic term (linear sigma model). This happens at the expense of introducing a suitable effective scalar potential, which contains the information on the curvature of the space. The simplified path integral provides a sensible gain in the efficiency of perturbative calculations. Here we extend the construction to models with N = 1 supersymmetry on the worldline, which are applicable to the first quantized description of a Dirac fermion. As an application we use the simplified worldline path integral to compute the type-A trace anomaly of a Dirac fermion in d dimensions up to d = 16
Small-scale Tests of Inflation
We investigate small-scale signatures of the inflationary particle content.
We consider the case of a light spin-2 particle sourcing primordial
gravitational waves by employing an effective field theory description. Upon
allowing time-dependent sound speeds for the helicity modes, this setup
delivers a blue tensor spectrum detectable, for example, by upcoming laser
interferometers. Our focus is on the tensor non-Gaussianities that ensue from
this field configuration. After characterising the bispectrum amplitude and
shape-function at CMB scales, we move on to smaller scales where anisotropies
induced in the tensor power spectrum by long-short modes coupling become the
key handle on (squeezed) primordial non-Gaussianities. We identify the
parameter space generating percent level anisotropies at scales soon to be
probed by SKA and LISA.Comment: 24 pages, 15 figures. Version accepted for publicatio
Novel CMB constraints on the parameter in alpha-attractor models
Cosmological -attractors are a compelling class of inflationary
models. They lead to universal predictions for large-scale observables, broadly
independent from the functional form of the inflaton potential. In this work we
derive improved analytical predictions for the large-scale observables, whose
dependence on the duration of reheating and the parameter is made
explicit. We compare these with Planck and BICEP/Keck 2018 data in the
framework of a Bayesian study, employing uniform logarithmic and linear priors
for . Our improved universal predictions allow direct constraints on
the duration of reheating. Furthermore, while it is well-known that CMB
constraints on the tensor-to-scalar ratio can be used to place an upper bound
on the parameter, we demonstrate that including the
-dependence of the scalar spectral tilt yields novel constraints on
. In particular, for small , the scalar spectral tilt scales
with , regardless of the specific potential shape. For
decreasing , this eventually puts the models in tension with CMB
measurements, bounding the magnitude of from below. Therefore, in
addition to the upper bound from the tensor-to-scalar ratio, we derive the
first lower bound on the magnitude of for -attractor T-models,
at C.L. .Comment: version accepted for publication in JCA
Interferometer constraints on the inflationary field content
With an energy scale that can be as high as , inflation
may provide a unique probe of high-energy physics. Both scalar and tensor
fluctuations generated during this early accelerated expansion contain crucial
information about the particle content of the primordial universe. The advent
of ground- and space-based interferometers enables us to probe primordial
physics at length-scales much smaller than those corresponding to current CMB
constraints. One key prediction of single-field slow-roll inflation is a
red-tilted gravitational wave spectrum, currently inaccessible at
interferometer scales. Interferometers probe directly inflationary physics that
deviates from the minimal scenario and in particular additional particle
content with sizeable couplings to the inflaton field. We adopt here an
effective description for such fields and focus on the case of extra spin-2
fields. We find that a time-dependent sound speed for the helicity-2 modes can
generate primordial gravitational waves with a blue-tilted spectrum,
potentially detectable at interferometer scales.Comment: 15 pages, 6 figures; references added; version matching the one
published in JCA
Presence in the pre-surgical fine-needle aspiration of potential thyroid biomarkers previously identified in the post-surgical one.
Fine-needle aspiration biopsy (FNA) is usually applied to distinguish benign from malignant thyroid nodules. However, cytological analysis cannot always allow a proper diagnosis. We believe that the improvement of the diagnostic capability of pre-surgical FNA could avoid unnecessary thyroidectomy. In a previous study, we performed a proteome analysis to examine FNA collected after thyroidectomy. With the present study, we examined the applicability of these results on pre-surgical FNA. We collected pre-surgical FNA from 411 consecutive patients, and to obtain a correct comparison with our previous results, we processed only benign (n=114), papillary classical variant (cPTC) (n=34) and papillary tall cell variant (TcPTC) (n=14) FNA. We evaluated levels of five proteins previously found up-regulated in thyroid cancer with respect to benign nodules. ELISA and western blot (WB) analysis were used to assay levels of L-lactate dehydrogenase B chain (LDHB), Ferritin heavy chain, Ferritin light chain, Annexin A1 (ANXA1), and Moesin in FNA. ELISA assays and WB analysis confirmed the increase of LDHB, Moesin, and ANXA1 in pre-surgical FNA of thyroid papillary cancer. Sensitivity and specificity of ANXA1 were respectively 87 and 94\% for cPTC, 85 and 100\% for TcPTC. In conclusion, a proteomic analysis of FNA from patients with thyroid nodules may help to distinguish benign versus malignant thyroid nodules. Moreover, ANXA1 appears to be an ideal candidate given the high sensitivity and specificity obtained from ROC curve analysis
Proteomic approach used in the diagnosis of Riedel's thyroiditis: a case report
<p>Abstract</p> <p>Introduction</p> <p>Riedel's thyroiditis, a rare thyroid disease, can be difficult to diagnose prior to surgical removal and can be confused with malignancy both clinically and cytologically.</p> <p>Case presentation</p> <p>We report the case of a 72-year-old Caucasian woman who presented with a goiter, which showed a rapid increase in size at ultrasound check, suggesting malignancy. Because of inconclusive cytology, a total thyroidectomy was performed. Fine-needle aspiration of the removed thyroid was processed by two-dimensional electrophoresis, and the proteome was compared with both anaplastic cancer and control samples. Significant differentially expressed protein spots were identified by Western blot analysis by using specific antibodies.</p> <p>Conclusions</p> <p>The protein pattern of Riedel's fine-needle aspiration revealed a superimposition with that of the control samples. The comparison of the protein pattern of Riedel's thyroiditis fine-needle aspiration with that of anaplastic cancer showed evidence of a different expression of ferritin heavy chains, ferritin light chains, and haptoglobins, as previously reported in thyroid cancers. Therefore, we performed Western blot analysis of these proteins and validated that their expression levels were low or absent in Riedel's thyroiditis and control samples despite the high concentrations present in fine-needle aspiration anaplastic samples. The concurrent absent or low expression levels of haptoglobin, ferritin light chain, and ferritin heavy chain in Riedel's thyroiditis fine-needle aspiration samples strongly indicate the benign nature of the thyroid lesion. These results suggest the potential applicability of fine-needle aspiration proteome analysis for Riedel's thyroiditis diagnosis.</p
Ultra-High-Frequency GWs: A Theory and Technology Roadmap
We consider primordial gravitational waves induced by large density perturbations generated by inflation in the very early universe. Cosmological alpha-attractors stand out as particularly compelling models to describe inflation, naturally meeting tight observational bounds from cosmic microwave background (CMB) experiments. We investigate alpha-attractor potentials in presence of an inflection point. The curvature perturbation is enhanced at high frequencies, which can lead to primordial black holes production and second-order gravitational waves. Consistency with the current CMB measurements implies that PBHs can only be produced with masses smaller than 10^8 g and are accompanied by ultra-high frequency gravitational waves, with a peak expected to be at frequencies of order 1MHz or above
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Loop corrections in the separate universe picture
In inflationary models that produce a spike of power on short scales,
back-reaction of small-scale substructure onto large-scale modes is enhanced.
We argue that the separate universe framework provides a highly convenient tool
to compute loop corrections that quantify this back-reaction. Each loop of
interest is characterized by large hierarchies in wavenumber and horizon exit
time. The separate universe framework highlights important factorizations
involving these hierarchies. We interpret each loop correction in terms of a
simple, classical, back-reaction model, and clarify the meaning of the
different volume scalings that have been reported in the literature. We argue
that significant back-reaction requires both short-scale nonlinearities and
long-short couplings that modulate the short-scale power spectrum. In the
absence of long-short couplings, only incoherent shot noise-like effects are
present, which are volume-suppressed. Dropping the shot noise, back-reaction
from a particular scale is controlled by a product of -like parameters:
an equilateral configuration measuring the nonlinearity of the short-scale
modes, and a squeezed configuration measuring the long-short coupling. These
may carry important scale dependence controlling the behaviour of the loop in
the decoupling limit where the hierarchy of scales becomes large. In
single-field models the long-short coupling may be suppressed by this
hierarchy, in which case the net back-reaction would be safely suppressed. We
illustrate our framework using explicit computations in a 3-phase
ultra-slow-roll scenario. Finally, we discuss different choices for the
smoothing scale used in the separate universe framework and argue the effect
can be absorbed into a renormalization of local operators.</p
Fine-needle aspiration of thyroid nodules: Proteomic analysis to identify cancer biomarkers
At present, the clinical and pathological analysis used in the diagnosis of papillary thyroid cancer (PTC) are insufficient to discern tumor behavior, and new diagnostic and prognostic markers need to be identified. In this study, we performed a comparative proteome analysis to examine the global changes of fine needle aspiration fluid (FNA) protein patterns of two variants of malignant PTC (classical variant PTC (cPTC) and tall cell variant PTC (TCV)) with respect to the controls. Changes in protein expression were identified using two-dimensional electrophoresis (2DE) and peptide mass fingerprinting via MALDI-TOF mass spectrometry (MS), as well as Western blot analysis. A statistical significant up-regulation of 17 protein spots in cPTC and/or TCV with respect to controls was demonstrated. These proteins included transthyretin precursor (TTR), ferritin light chain (FLC), proteasome activator complex subunit 1 and 2, alpha-1-antitrypsin precursor, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase chain B (LDH-B), apolipoprotein A1 precursor (Apo-A1), annexin A1, DJ-1 protein and cofilin-1. In addition, 12 protein spots were found exclusively in cPTC and three exclusively in TCV. These latter proteins (ferritin heavy chain (FHC), peroxiredoxin 1 (PRX1) and 6-phosphogluconate dehydrogenase (6-PDGH)) correspond to stress response proteins and, until now, had not been described in thyroid tumors. These findings illustrate the potential use of FNA proteomics to identify protein changes associated with thyroid cancer and to advance potential protein biomarkers in the diagnostic classification of the disease