20 research outputs found
The Conformal Anomaly and the Neutral Currents Sector of the Standard Model
We elaborate on the structure of the graviton-gauge-gauge vertex in the
electroweak theory, obtained by the insertion of the complete energy-momentum
tensor () on 2-point functions of neutral gauge currents (). The vertex
defines the leading contribution to the effective action which accounts for the
conformal anomaly and related interaction between the Standard Model and
gravity. The energy momentum tensor is derived from the curved spacetime
Lagrangian in the linearized gravitational limit, and with the inclusion of the
term of improvement of a conformally coupled Higgs sector. As in the previous
cases of QED and QCD, we find that the conformal anomaly induces an effective
massless scalar interaction between gravity and the neutral currents in each
gauge invariant component of the vertex. This is described by the exchange of
an anomaly pole. We show that for a spontaneously broken theory the anomaly can
be entirely attributed to the poles only for a conformally coupled Higgs
scalar. In the exchange of a graviton, the trace part of the corresponding
interaction can be interpreted as due to an effective dilaton, using a local
version of the effective action. We discuss the implications of the anomalous
Ward identity for the correlator for the structure of the gauge/gauge/
effective dilaton vertex in the effective action. The analogy between these
effective interactions and those related to the radion in theories with large
extra dimensions is pointed out.Comment: 19 pages, 10 figures. Extended version, To appear in Phys. Lett.
Dilaton Interactions and the Anomalous Breaking of Scale Invariance of the Standard Model
We discuss the main features of dilaton interactions for fundamental and
effective dilaton fields. In particular, we elaborate on the various ways in
which dilatons can couple to the Standard Model and on the role played by the
conformal anomaly as a way to characterize their interactions. In the case of a
dilaton derived from a metric compactification (graviscalar), we present the
structure of the radiative corrections to its decay into two photons, a photon
and a , two gauge bosons and two gluons, together with their
renormalization properties. We prove that, in the electroweak sector, the
renormalization of the theory is guaranteed only if the Higgs is conformally
coupled. For such a dilaton, its coupling to the trace anomaly is quite
general, and determines, for instance, an enhancement of its decay rates into
two photons and two gluons. We then turn our attention to theories containing a
non-gravitational (effective) dilaton, which, in our perturbative analysis,
manifests as a pseudo-Nambu Goldstone mode of the dilatation current ().
The infrared coupling of such a state to the two-photons and to the two-gluons
sector, and the corresponding anomaly enhancements of its decay rates in these
channels, is critically analyzed.Comment: Revised version, 42 pages, 5 figure
Insights into cognitive and behavioral comorbidities of SLC6A1-related epilepsy: five new cases and literature review
IntroductionSLC6A1 pathogenic variants have been associated with epilepsy and neurodevelopmental disorders. The clinical phenotype includes different seizure types, intellectual disability, and psychiatric symptoms affecting mood and behavior. Few data regarding neuropsychological features have been described, and details on cognitive profiles are often missing due to the lack of standardized tests.MethodsWe retrospectively reviewed the neuropsychological assessments of five subjects carrying heterozygous missense genetic variants in SLC6A1. We also collected data on epileptic features, EEGs, and brain MRIs. Additionally, we reviewed neuropsychological data from 204 previously reported patients with SLC6A1 pathogenic variants.ResultsIn our series, at the last evaluation (median 12.6 years), three patients had borderline intellectual functioning, one patient had mild cognitive impairment, and one patient presented with a moderate cognitive disability. Three out of five patients underwent at least two neuropsychological evaluations, which revealed a worsening of cognitive functions over time. We detected attention deficits in all patients. In addition, we observed anxiety, disruptive behavior disorder, emotional instability, and hetero aggressiveness. We also performed a literature review that highlighted that most of the patients with SLC6A1 pathogenic variants have mild-to-moderate intellectual disability and that one-third of cases have autistic traits.DiscussionBased on the literature review and the detailed description of our cases, we conclude that patients with SLC6A1-related epilepsy mostly present with mild-to-moderate intellectual disability, often associated with attention disorders. Such symptoms may worsen over time. Periodic standardized neuropsychological tests may be useful tools to follow development over time, and patient-specific rehabilitation programs could be tailored consistently
Progettazione di un ponte strallato ciclopedonale sul fiume Arno tra Riglione e Cisanello
La tesi riguarda la progettazione strutturale ed architettonica di un ponte ciclopedonale, che colleghi gli itinerari ciclabili su due lati del fiume Arno a Pisa, presso gli abitati di Riglione e di Cisanello. L’opera programmata all’interno della “ciclopista dell’Arno” diverrebbe, inoltre una infrastruttura a servizio del policlinico cittadino che negli ultimi anni ha subito una eccezionale trasformazione ed un progressivo ampliamento. La soluzione adottata prevede la realizzazione di un ponte strallato in carpenteria metallica senza appoggi intermedi che prosegue con un viadotto in grado di consentire il superamento dell’ampia area golenale presente sulla sponda destra del fiume. A seguito della creazione di un modello FEM tridimensionale è stata valutata la sicurezza strutturale e geotecnica secondo le normative europee e italiane e sono stati infine studiati i fenomeni relativi alle vibrazioni indotte dai pedoni per mezzo di analisi dinamiche non lineari (time history)
F7 gene variants modulate protein levels in a large cohort of patients with factor VII deficiency: Results from a genotype-phenotype study
Congenital factor VII (FVII) deficiency is a rare bleeding disorder caused by mutations in F7 gene with autosomal recessive inheritance. A clinical heterogeneity with poor correlation with FVII:C levels has been described. It was the objective of this study to identify genetic defects and to evaluate their relationships with phenotype in a large cohort of patients with FVII:C<50 %. One hundred twenty-three probands were genotyped for F7 mutations and three polymorphic variants and classified according to recently published clinical scores. Forty out of 123 patients (33 %) were symptomatic (43 bleedings). A severe bleeding tendency was observed only in patients with FVII:C<0.10 %. Epistaxis (11 %) and menorrhagia (32 % of females in fertile age) were the most frequent bleedings. Molecular analysis detected 48 mutations, 20 not reported in the F7 international databases. Most mutations (62 %) were missense, large deletions were 6.2 %. Compound heterozygotes/homozygotes for mutations presented lower FVII:C levels compared to the other classes (Chi2=43.709, p<0,001). The polymorphisms distribution was significantly different among the three F7 genotypic groups (Chi2=72.289, p<0,001). The presence of truncating mutations was associated with lowest FVII:C levels (Chi2=21.351, p=0.002). This study confirms the clinical and molecular variability of the disease and the type of symptoms. It shows a good correlation between the type of F7 mutation and/or polymorphisms and FVII:C levels, without a direct link between FVII:C and bleeding tendency. The results suggest that large deletions are underestimated and that they represent a common mechanism of F7 gene inactivation which should always be investigated in the diagnostic testing for FVII deficiency
Narrow-bandwidth picosecond pulses by spectral compression of femtosecond pulses in second-order nonlinear crystals
We introduce a simple approach for the efficient generation of
tunable narrow-bandwidth picosecond pulses synchronized to broadband
femtosecond ones. Second harmonic generation in the presence of large
group velocity mismatch between the interacting pulses transfers a large
fraction of the energy of a broadband fundamental frequency pulse into a
narrowband second harmonic one. Using a periodically poled stoichiometric
lithium tantalate crystal coupled to an infrared optical parametric amplifier,
we generated 200-nJ pulses with spectral width lower than 8.5 cm-1 and
tunability from 720 to 890 nm. Energy scaling and extension of the tuning
range are straightforward