448 research outputs found
Anomalous decay of a prepared state due to non-Ohmic coupling to the continuum
We study the decay of a prepared state into a continuum {E_k} in the
case of non-Ohmic models. This means that the coupling is with . We find that irrespective of model details
there is a universal generalized Wigner time that characterizes the
evolution of the survival probability . The generic decay behavior
which is implied by rate equation phenomenology is a slowing down stretched
exponential, reflecting the gradual resolution of the bandprofile. But
depending on non-universal features of the model a power-law decay might take
over: it is only for an Ohmic coupling to the continuum that we get a robust
exponential decay that is insensitive to the nature of the intra-continuum
couplings. The analysis highlights the co-existence of perturbative and
non-perturbative features in the dynamics. It turns out that there are special
circumstances in which is reflected in the spreading process and not only
in the survival probability, contrary to the naive linear response theory
expectation.Comment: 13 pages, 11 figure
Hapten-reactive inducer T cells. I. Definition of two classes of hapten-specific inducer cells.
Quantum decay into a non-flat continuum
We study the decay of a prepared state into non-flat continuum. We find that
the survival probability might exhibit either stretched-exponential or
power-law decay, depending on non-universal features of the model. Still there
is a universal characteristic time that does not depend on the functional
form. It is only for a flat continuum that we get a robust exponential decay
that is insensitive to the nature of the intra-continuum couplings. The
analysis highlights the co-existence of perturbative and non-perturbative
features in the local density of states, and the non-linear dependence of
on the strength of the coupling.Comment: 10 pages, 4 figure
The IGSF1 deficiency syndrome may present with normal free T4 levels, severe obesity, or premature testicular growth
Our objective was to further expand the spectrum of clinical characteristics of the IGSF1 deficiency syndrome in affected males. These characteristic include almost universal congenital central hypothyroidism (CeH) with disharmonious pubertal development (normally timed testicular growth, but delayed rise of serum testosterone), macroorchidism, increased body mass index (BMI), and decreased attentional control. In addition, a subset of patients show prolactin deficiency, transient partial growth hormone deficiency in childhood and increased growth hormone secretion in adulthood. We present a family in which the proband was diagnosed with CeH and low serum prolactin. Severe weight gain started at two years old, with a BMI of 42.3 at 13.9 years. Testicular enlargement (5-6 mL, 3.8-4.3 standard deviation score) started aged three years. A pathogenic variant was found in the IGSF1 gene: c.3411_3412del, p.(Tyr1137*). His brother was referred for short stature at age 13 years and was diagnosed with CeH, normal serum prolactin and IGF-1, and disharmonious puberty. In four male relatives (the proband's brother and three cousins) with the variant (one adult), free thyroxine (fT4) was below the lower limit of the reference range in two, and just above this limit in the other two. Three were overweight or obese, adolescents had disharmonious pubertal development and the adult had profound macroorchidism. In conclusion, male hemizygous carriers of a pathogenic IGSF1 variant can present with fT4 concentration above the lower limit of the reference range while severe early onset obesity or premature testicular growth are part of the phenotypic spectrum.Genetics of disease, diagnosis and treatmen
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