112,629 research outputs found
Numeri q-perfetti e q-amicabili di seconda specie e altre generalizzazioni dei numeri perfetti di seconda specie
No full textNel presente lavoro si affronta, tra le curiosità matematiche, il problema dei
numeri perfetti di seconda specie, riprendendo anche un lavoro del 1979 di Franco
Eugeni e Bruno Rizzi, utilizzato come preambolo e spunto per le problematiche
lasciate aperte su tali concetti, e le loro generalizzazioni tra le quali quella dei
numeri q-perfetti di 2 a specie. Il presente file si compone infatti di:
1. Su alcune generalizzazioni dei numeri perfetti, tratto dal periodico di
matematiche serie V Volume 56 del 1980 riguardanti i numeri 1-perfetti di
2 a specie e alcune problematiche dei numeri q-perfetti di 2 a specie. Il testo
è corredato di note scritte in questa occasione.
2. Un lavoro che appare qui per la prima volta in cui è trattato, per quanto sia
possibile, il caso q > 1 per la suddetta generalizzazione dei numeri perfetti
di 2 a specie e una diversa generalizzazione dei numeri perfetti di 2 a specie
insieme a risultati sul problema delle coppie di numeri amicabili di
seconda specie, per entrambe le generalizzazioni
A Nekhoroshev Theorem for some Infinite Dimensional Systems
No full textWe study the persistence for
long times of the solutions of some infinite--dimensional discrete
hamiltonian systems with {\it formal hamiltonian}
\sum_{i=1}^\infty h(A_i) + V(\vp), (A,\vp)\in {\Bbb R}^{\Bbb
N}\times {\Bbb T}^{\Bbb N}. V(\vp) is not needed small and the
problem is perturbative being the kinetic energy unbounded. All
the initial data (A_i(0), \vp_i(0)), in the
phase--space give
rise to solutions with close to zero for
exponentially--long times provided that is large enough
for large. We need \o \partial h,\partial
A_i,{\scriptstyle (A_i(0))} unbounded for making
\vp_i a {\it fast variable}; the greater is the faster is
the angle \vp_i (avoiding the resonances). The estimates are
obtained in the spirit of the averaging theory reminding the
analytic part of Nekhoroshev--theorem
An infinite-dimensional extension of a Poincar\'e's result concerning the continuation of periodic orbits
No full textWe study the existence of periodic
solutions for
the infinite-dimensional second order system
Using the Implicit-Function-Theorem, we prove the
existence of time-periodic solutions at \lq\lq high frequencies"; no \lq\lq
smallness condition" on is required
Second Order Hamiltonian Equations on \T^\iocand Almost--Periodic Solutions
No full textMotivated by problems arising in
nonlinear PDE's with a Hamiltonian structure and in high dimensional
dynamical systems, we study a suitable generalization to infinite
dimensions of second order Hamiltonian equations of the type
\ddot x=\dpr_x V, [x\in\TN, \dpr_x\=(\dpr_{x_1},...,
\dpr_{x_N})].
Extending methods from quantitative perturbation theory
(Kolmogorov--Arnold--Moser theory, Nash--Moser implicit function
theorem,
\etc) we construct uncountably many almost--periodic solutions for the
infinite dimensional system , i\in \Zd, x\in
\T^\Zd (endowed with the compact topology); the Hamiltonian structure
is reflected by being a ``generalized gradient". Such result is
derived under (suitable) analyticity assumptions on but without
requiring any ``smallness conditions"
Insights into the regulation of immunoglobulin light chain gene rearrangements via analysis of the kappa light chain locus in lambda myeloma
No full textAccumulating evidence indicates that B cells may undergo sequential rearrangements at the light chain loci, despite already expressing light chain receptors. This phenomenon may occur in the bone marrow and, perhaps, in germinal centers. As immunoglobulin (Ig)kappa light chains usually rearrange before Iglambda light chains, we analysed, by polymerase chain reaction, the Igkappa locus of bone marrow mononuclear cells from 29 patients with Iglambda myeloma to identify earlier recombinations in marrow plasma cells. The results demonstrated that Igkappa alleles were inactivated via the kappa-deleting element, presumably prior to V(kappa)-J(kappa) rearrangement, in many cases. Eighteen alleles (16 myeloma clones, 55%) showed V(kappa)-J(kappa) rearrangements, with increased utilization of 5' distant V(kappa) and 3' distant Jkappa gene segments (Jkappa4, 56%), an indication of multiple sequential rearrangements. In-frame, potentially functional V(kappa)-J(kappa) rearrangements were found in approximately one-third of available rearrangements (as expected by chance), each one in different myeloma clones: three were germline encoded, while one had several nucleotide substitutions, suggesting inactivation after the onset of somatic hypermutation. Three of four potentially functional V(kappa)-J(kappa)rearrangements involved V(kappa)4-1, a segment considered to be associated with autoimmunity. These findings provide insights into the regulation of light chain rearrangements and support the view that B cells may occasionally undergo sequential light chain rearrangements after the onset of somatic hypermutation
Diagnostic corner: Internal Medicine
No full textUn gatto comune europeo, maschio castrato, di 7 anni, è stato riferito per poliuria e polidipsia, ipercalcemia e disoressia persistente nonostante vari cambiamenti dietetici. La concentrazione di paratormone misurata dal veterinario curante era risultata nei range di riferimento
Detection of station coordinate discontinuities within the Italian GPS Fiducial Network
No full textThe Detection Identification Adaptation (DIA)
procedure was applied to the coordinate time-series of some
permanentGPS stations belonging to the ItalianGPS Fiducial
Network (IGFN), of the Italian Space Agency (ASI), to detect
discontinuities and to reject outliers. The daily solutions of
the stations of Cagliari, Genoa,Medicina, Noto, Turin, Perugia
and Venice were computed for the period 1997.0–2003.0
using Bernese GPS software v.4.2. The data were interpolated
using a model with a linear term and an annual periodic
term. The parameters were estimated by least squares. The
DIA procedure was organized to automatically detect discontinuities
and outliers. Approximately, 70% of the discontinuities
present in the coordinate time-series were identified
and their magnitudes were estimated. The identified discontinuities
are basically caused by equipment replacement and
reference frame changes, but in a few cases the reason is
still unknown.With regard to the outliers, roughly 6% of the
data were rejected. These data were considered outliers on
the base of the level of significance and of the power of the
test adopted in this work. Except for the stations of Perugia
and Venice, the estimated coordinates agree with ITRF2000
values at the 10mm level, and the estimated velocities are
within a few mm/year of the ITRF2000 values
Therapy and management of systemic AL (primary) amyloidosis
No full textThe optimal treatment of immunoglobulin light chain amyloidosis (AL) patients requires early diagnosis, correct amyloid typing, effective treatment and careful supportive therapy. In the last few years the therapeutic arsenal for the management of AL has been considerably enriched. Cardiac dysfunction can be accurately monitored by measuring the serum concentration of natriuretic peptide type-B and cardiac troponins and the quantitative test for circulating free light chains allows an easy assessment of haematological response to chemotherapy. These new tools can be combined in order to maximise the improvement of organ dysfunction and minimise toxicity, adapting the intervention to each patient
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