115 research outputs found
L’inibizione tireotropinica da metformina non si associa a segni cardiologici di ipertiroidismo subclinico
Recenti dati di letteratura hanno evidenziato come metformina determini una riduzione/soppressione dei livelli sierici di tireotro- pina (TSH), simulando un ipertiroidismo subclinico il cui signifi- cato clinico rimane a oggi ancora assai controverso. Sebbene l’ipertiroidismo subclinico sia nella maggioranza dei casi una condizione clinica asintomatica, è altrettanto noto come esso si associ a un aumentato rischio di aritmie (più frequentemente la fibrillazione atriale) e ad alterazioni morfo-funzionali cardiache determinando un aumento di morbilità e mortalità cardiovasco- lare. Scopo del presente studio è stato quello di valutare retrospetti- vamente le alterazioni di differenti indici elettrocardiografici in pazienti diabetici eutiroidei che, dopo aver intrapreso terapia con metformina, hanno sviluppato riduzione/soppressione dei valori di TSH comparando i dati con quelli ottenuti in pazienti con iper- tiroidismo subclinico secondario a patologie tiroidee o a terapia soppressiva con L-tiroxina. I parametri elettrocardiografici (frequenza cardiaca, durata del- l’onda P, indice di dispersione dell’onda P, QT max, QT min, indice di dispersione dell’intervallo QT) sono stati valutati in 23 pazienti diabetici in terapia con metformina prima e dopo 6 mesi dall’instaurarsi della soppressione del TSH e in 31 con- trolli con ipertiroidismo subclinico. Nessuna modifica significa- tiva è stata osservata tra i parametri elettrocardiografici rilevati prima e dopo la riduzione del TSH. Al contrario, significative dif- ferenze nella durata dell’onda P (102,9 ± 7,4 vs 92,1 ± 5,8 ms, p < 0,001), dell’indice di dispersione dell’onda P (13,1 ± 3,4 vs 7,1 ± 3,5 ms, p < 0,001), del QT max (399 ± 18 vs 388 ± 16 ms, p = 0,024), del QT min (341 ± 14 vs 350 ± 17 ms, p = 0,038) e di quello dell’intervallo QT (49,9 ± 9,6 vs 30,9 ± 9,2 ms, p < 0,001) sono state rilevate tra i controlli con iperti- roidismo subclinico e il gruppo di pazienti diabetici con valori ridotti/soppressi di TSH. I risultati del nostro studio evidenzierebbero come l’effetto di riduzione/soppressione del TSH osservato in alcuni pazienti dia- betici in terapia con metformina non si associ a marker periferi- ci cardiaci da eccesso di ormoni tiroidei. L’alterazione del profilo tiroideo metformina-indotto sembrerebbe non indicativo di iper- tiroidismo subclinico, suggerendo quindi che non sussiste la necessità di sottoporre a stretti controlli della funzione tiroidea i pazienti diabetici in terapia con metformin
The CUORE cryostat: an infrastructure for rare event searches at millikelvin temperatures
The CUORE experiment is the world's largest bolometric experiment. The
detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg.
CUORE is presently taking data at the Laboratori Nazionali del Gran Sasso,
Italy, searching for the neutrinoless double beta decay of 130Te. A large
custom cryogen-free cryostat allows reaching and maintaining a base temperature
of about 10 mK, required for the optimal operation of the detector. This
apparatus has been designed in order to achieve a low noise environment, with
minimal contribution to the radioactive background for the experiment. In this
paper, we present an overview of the CUORE cryostat, together with a
description of all its sub-systems, focusing on the solutions identified to
satisfy the stringent requirements. We briefly illustrate the various phases of
the cryostat commissioning and highlight the relevant steps and milestones
achieved each time. Finally, we describe the successful cooldown of CUORE
Xyloglucan endotransglucosylase and cell wall extensibility
Transgenic tomato hypocotyls with altered levels of an XTH gene were used to study how XET activity could affect the hypocotyl growth and cell wall extensibility. Transgenic hypocotyls showed significant over-expression (line 13) or co-suppression (line 33) of the SlXTH1 in comparison with the wild type, with these results being correlated with the results on specific soluble XET activity, suggesting that SlXTH1 translates mainly for a soluble XET isoenzyme. A relationship between XET activity and cell wall extensibility was found, and the highest total extensibility was located in the apical hypocotyl segment of the over-expressing SlXTH1 line, where the XET-specific activity and hypocotyl growth were also highest compared with the wild line
CUORE and beyond: bolometric techniques to explore inverted neutrino mass hierarchy
The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will
search for neutrinoless double beta decay of Te. With 741 kg of TeO
crystals and an excellent energy resolution of 5 keV (0.2%) at the region of
interest, CUORE will be one of the most competitive neutrinoless double beta
decay experiments on the horizon. With five years of live time, CUORE projected
neutrinoless double beta decay half-life sensitivity is y
at ( y at the 90% confidence level), which
corresponds to an upper limit on the effective Majorana mass in the range
40--100 meV (50--130 meV). Further background rejection with auxiliary light
detector can significantly improve the search sensitivity and competitiveness
of bolometric detectors to fully explore the inverted neutrino mass hierarchy
with Te and possibly other double beta decay candidate nuclei.Comment: Submitted to the Proceedings of TAUP 2013 Conferenc
Exploring the Neutrinoless Double Beta Decay in the Inverted Neutrino Hierarchy with Bolometric Detectors
Neutrinoless double beta decay (0nubb) is one of the most sensitive probes
for physics beyond the Standard Model, providing unique information on the
nature of neutrinos. In this paper we review the status and outlook for
bolometric 0nubb decay searches. We summarize recent advances in background
suppression demonstrated using bolometers with simultaneous readout of heat and
light signals. We simulate several configurations of a future CUORE-like
bolometer array which would utilize these improvements and present the
sensitivity reach of a hypothetical next-generation bolometric 0nubb
experiment. We demonstrate that a bolometric experiment with the isotope mass
of about 1 ton is capable of reaching the sensitivity to the effective Majorana
neutrino mass (|mee|) of order 10-20 meV, thus completely exploring the
so-called inverted neutrino mass hierarchy region. We highlight the main
challenges and identify priorities for an R&D program addressing them.Comment: 22 pages, 15 figures, submitted to EPJ
Search for Neutrinoless Double-Beta Decay of Te with CUORE-0
We report the results of a search for neutrinoless double-beta decay in a
9.8~kgyr exposure of Te using a bolometric detector array,
CUORE-0. The characteristic detector energy resolution and background level in
the region of interest are FWHM and ~counts/(keVkgyr), respectively. The
median 90%~C.L. lower-limit sensitivity of the experiment is and surpasses the sensitivity of previous searches. We find
no evidence for neutrinoless double-beta decay of Te and place a
Bayesian lower bound on the decay half-life, ~ at 90%~C.L. Combining CUORE-0 data with the 19.75~kgyr
exposure of Te from the Cuoricino experiment we obtain at 90%~C.L.~(Bayesian), the most stringent
limit to date on this half-life. Using a range of nuclear matrix element
estimates we interpret this as a limit on the effective Majorana neutrino mass,
-- .Comment: 6 pages, 5 figures, updated version as published in PR
CUORE-0 results and prospects for the CUORE experiment
With 741 kg of TeO2 crystals and an excellent energy resolution of 5 keV
(0.2%) at the region of interest, the CUORE (Cryogenic Underground Observatory
for Rare Events) experiment aims at searching for neutrinoless double beta
decay of 130Te with unprecedented sensitivity. Expected to start data taking in
2015, CUORE is currently in an advanced construction phase at LNGS. CUORE
projected neutrinoless double beta decay half-life sensitivity is 1.6E26 y at 1
sigma (9.5E25 y at the 90% confidence level), in five years of live time,
corresponding to an upper limit on the effective Majorana mass in the range
40-100 meV (50-130 meV). Further background rejection with auxiliary bolometric
detectors could improve CUORE sensitivity and competitiveness of bolometric
detectors towards a full analysis of the inverted neutrino mass hierarchy.
CUORE-0 was built to test and demonstrate the performance of the upcoming CUORE
experiment. It consists of a single CUORE tower (52 TeO2 bolometers of 750 g
each, arranged in a 13 floor structure) constructed strictly following CUORE
recipes both for materials and assembly procedures. An experiment its own,
CUORE-0 is expected to reach a sensitivity to the neutrinoless double beta
decay half-life of 130Te around 3E24 y in one year of live time. We present an
update of the data, corresponding to an exposure of 18.1 kg y. An analysis of
the background indicates that the CUORE performance goal is satisfied while the
sensitivity goal is within reach.Comment: 10 pages, 3 figures, to appear in the proceedings of NEUTRINO 2014,
26th International Conference on Neutrino Physics and Astrophysics, 2-7 June
2014, held at Boston, Massachusetts, US
Status of the CUORE and results from the CUORE-0 neutrinoless double beta decay experiments
CUORE is a 741 kg array of TeO2 bolometers for the search of neutrinoless
double beta decay of 130Te. The detector is being constructed at the Laboratori
Nazionali del Gran Sasso, Italy, where it will start taking data in 2015. If
the target background of 0.01 counts/keV/kg/y will be reached, in five years of
data taking CUORE will have a 1 sigma half life sensitivity of 10E26 y. CUORE-0
is a smaller experiment constructed to test and demonstrate the performances
expected for CUORE. The detector is a single tower of 52 CUORE-like bolometers
that started taking data in spring 2013. The status and perspectives of CUORE
will be discussed, and the first CUORE-0 data will be presented.Comment: 7 pages, 4 figures, to be published in the proceedings of ICHEP 2014,
37th International Conference on High Energy Physics, Valencia (Spain) 2-9
July 201
The low energy spectrum of TeO2 bolometers: results and dark matter perspectives for the CUORE-0 and CUORE experiments
We collected 19.4 days of data from four 750 g TeO2 bolometers, and in three
of them we were able to set the energy threshold around 3 keV using a new
analysis technique. We found a background rate ranging from 25 cpd/keV/kg at 3
keV to 2 cpd/keV/kg at 25 keV, and a peak at 4.7 keV. The origin of this peak
is presently unknown, but its presence is confirmed by a reanalysis of 62.7
kg.days of data from the finished CUORICINO experiment. Finally, we report the
expected sensitivities of the CUORE0 (52 bolometers) and CUORE (988 bolometers)
experiments to a WIMP annual modulation signal.Comment: 9 pages, 10 figure
Validation of techniques to mitigate copper surface contamination in CUORE
In this article we describe the background challenges for the CUORE
experiment posed by surface contamination of inert detector materials such as
copper, and present three techniques explored to mitigate these backgrounds.
Using data from a dedicated test apparatus constructed to validate and compare
these techniques we demonstrate that copper surface contamination levels better
than 10E-07 - 10E-08 Bq/cm2 are achieved for 238U and 232Th. If these levels
are reproduced in the final CUORE apparatus the projected 90% C.L. upper limit
on the number of background counts in the region of interest is 0.02-0.03
counts/keV/kg/y depending on the adopted mitigation technique.Comment: 10 pages, 6 figures, 6 table
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