620 research outputs found
Generalized Hyper-Ramsey Resonance with separated oscillating fields
An exact generalization of the Ramsey transition probability is derived to
improve ultra-high precision measurement and quantum state engineering when a
particle is subjected to independently-tailored separated oscillating fields.
The phase-shift accumulated at the end of the interrogation scheme offering
high-level control of quantum states throughout various laser parameters
conditions. The Generalized Hyper-Ramsey Resonance based on independent
manipulation of interaction time, field amplitude, phase and frequency detuning
is presented to increase the performance of next generation of atomic,
molecular and nuclear clocks, to upgrade high resolution frequency measurement
in Penning trap mass spectrometry and for a better control of light induced
frequency shifts in matter wave interferometers or quantum information
processing.Comment: accepted for publication in Phys. Rev.
Composite pulses in Hyper-Ramsey spectroscopy for the next generation of atomic clocks
The next generation of atomic frequency standards based on an ensemble of
neutral atoms or a single-ion will provide very stringent tests in metrology,
applied and fundamental physics requiring a new step in very precise control of
external systematic corrections. In the proceedings of the 8th Symposium on
Frequency Standards and Metrology, we present a generalization of the recent
Hyper-Ramsey spectroscopy with separated oscillating fields using composites
pulses in order to suppress field frequency shifts induced by the interrogation
laser itself. Sequences of laser pulses including specific selection of phases,
frequency detunings and durations are elaborated to generate spectroscopic
signals with a strong reduction of the light-shift perturbation by off resonant
states. New optical clocks based on weakly allowed or completely forbidden
transitions in atoms, ions, molecules and nuclei will benefit from these
generalized Ramsey schemes to reach relative accuracies well below the
10 level.Comment: accepted as proceedings of the 8th Symposium on Frequency Standards
and Metrology (Potsdam Germany, 12-16 october 2015
Synthetic Frequency Protocol in the Ramsey Spectroscopy of Clock Transitions
We develop an universal method to significantly suppress probe-induced shifts
in any types of atomic clocks using the Ramsey spectroscopy. Our approach is
based on adaptation of the synthetic frequency concept [V. I. Yudin, et al.,
Phys. Rev. Lett. 107, 030801 (2011)] (previously developed for BBR shift
suppression) to the Ramsey spectroscopy with the use of interrogations for
different dark time intervals. Universality of the method consists in
arbitrariness of the possible Ramsey schemes. However, most extremal results
are obtained in combination with so-called hyper-Ramsey spectroscopy [V. I.
Yudin, et al., Phys. Rev. A 82, 011804(R) (2010)]. In the latter case, the
probe-induced frequency shifts can be suppressed considerably below a
fractional level of 10 practically for any optical atomic clocks, where
this shift previously was metrologically significant. The main advantage of our
method in comparison with other radical hyper-Ramsey approaches [R. Hobson, et
al., Phys. Rev. A 93, 010501(R) (2016); T. Zanon-Willette, et al., Phys. Rev. A
93, 042506 (2016)] consist in much greater efficiency and resistibility in the
presence of decoherentization.Comment: 9 pages, 7 figure
STEM CELL-LIKE PROPERTIES OF MEMORY T CELLS IN HUMAN IMMUNE RECONSTITUTION
ABSTRACT
The memory T cell compartment comprises a plethora of subsets that are diverse at the
functional, transcriptional and metabolic level. T memory stem cells (TSCM) are the least
differentiated subset endowed with superior immune reconstitution capacity, anti-tumor
activity and long-term persistence compared to more differentiated progeny in preclinical
models. However, their role in human T cell recovery remains undetermined.
In the first part of my work, I investigate the dynamics of T cell reconstitution in human
haploidentical bone marrow transplantation (haplo-BMT) with post-transplant
cyclophosphamide (pt-Cy) and provide evidence that donor antigen-specific na\uefve (TN)-
derived TSCM cells survive pt-Cy and are the most abundant circulating T cell population in
the early days after transplantation. I further demonstrate that these cells later contribute to
peripheral reconstitution by differentiating into effector cells. With these experiments, I
define the cellular basis of human T cell reconstitution following haploidentical
transplantation with pt-Cy and propose to employ naive-derived TSCM cells in the clinical
setting to overcome immunodeficiency. However, the clinical use of these cells is limited by
their paucity ex vivo. Therefore, I dedicate the second part of this work to investigate the
biological and molecular mechanisms involved in the generation and expansion of TSCM cells
from CD8+ TN precursors. I show that curtailed T-cell receptor stimulation curbs effector
CD8+ T-cell differentiation and allows the generation of CD45RO\u2013
CD45RA+CCR7+CD27+CD95+ -phenotype cells from highly purified TN precursors,
resembling naturally-occurring TSCM. These cells proliferate extensively in vitro and in vivo,
express low amounts of effector-associated genes and transcription factors and undergo
considerable self-renewal in response to IL-15 while retaining effector differentiation
potential. Such a phenotype is associated with a lower number of mitochondria compared to
highly-activated effector T cells committed to terminal differentiation. These results shed
light on the molecular signals that are required to generate high numbers of long-lived
memory T cells with potential application in adoptive cell transfer immunotherapy
Un metodo per riconoscere faglie attive sepolte mediante misure areali di radon dal suolo
Lo studio riassume i risultati di una campagna
di misure geochimiche e strutturali
condotte nel 2004 (Neri et al., 2011) e
riguarda la misurazione delle emissioni
di gas radon e thoron dal suolo effettuate lungo
il fianco orientale dell’Etna, in una zona caratterizzata
dalla presenza di numerose faglie attive.
Le elaborazioni statistiche effettuate hanno
permesso di riconoscere soglie di anomalia
dei dati geochimici, nonché la produzione di
mappe di distribuzione che hanno evidenziato
una significativa correlazione spaziale tra le
anomalie riscontrate e i principali lineamenti
tettonici. Entrambe le anomalie di radon e
thoron si trovavano in aree interessate da sismicitÃ
relativamente profonda, in particolare
in corrispondenza delle zone di intersezione tra
faglie differentemente orientate. Questo studio
conferma che la mappatura della distribuzione
di gas radon e thoron dal suolo può rivelare la
presenza di faglie nascoste da coperture recenti,
o faglie che non sono chiaramente visibili
in superficie
Reproductive parameters of "Nero di Parma" sows reared outdoor and indoor
AbstractThe swine genetic type "Nero di Parma" has been obtained after a preservation programme of a local breed suitable for outdoor rearing systems in Parma province. Actually, 480 females and 35 males are registered by Italian Swine Breeders Association and are reared in 28 herds of Parma province. The study involved the analysis of the reproductive performance of 120 sows from 19 boars, born between 1999 and 2005, during 211 parities from 2002 to 2006. For each parity, the boar, the age of the sow, the length of the farrowing interval, and the litter size (number of born alive, stillborn and weaned piglets) were recorded. Two rearing systems of the farrowing sows (from the final phase of gestation to the end of lactation) were considered: indoor (sows closed off in individual stalls or farrowing cages) and outdoor (sows in individual huts inside the paddocks, with straw bedding); dry sows in both systems had access on pasture with forage and concentrate integration. Data concerning sows performance we..
Prediction of milk, fat and protein yields in first lactation from serum ß-lactoglobulin concentrations during gestation in Italian Brown heifers
The Authors report the results of a study carried out on 23 pregnant Italian Brown heifers, with the aim to determine the relationships between blood serum ß-lactoglobulin (ß-LG) concentrations during first gestation and subsequent milk production and quality in first lactation, in order to obtain an improved selection method for replacement heifers. At weeks 20, 26 and 32 of gestation, ß-LG concentrations (±SE) were 706±78, 753±66 and 772±63 ng/ml, respectively (P>0.05). High and significant (P≤0.05) correlation coefficients were observed only between ß-LG content at week 32 and total milk and protein yields in first lactation. Prediction equations of milk, fat and protein production in first lactation from log10 ß-LG content at week 32 of gestation, from parent average genetic indexes and from both were calculated by means of multiple regression analysis. When the contribution of both ß-LG content and predicted genetic indexes were considered, the regression equations gave generally a better estimate of the production parameters in first lactation (higher R2, lower SE of estimate) than the above mentioned parameters alone. These results suggest that it is valuable to pre-estimate milk, fat and protein production in Italian Brown first lactating cows by means of the analysis of serum ß-LG content during gestation
Un metodo per riconoscere faglie attive sepolte mediante misure areali di radon dal suolo
Lo studio riassume i risultati di una campagna
di misure geochimiche e strutturali
condotte nel 2004 (Neri et al., 2011) e
riguarda la misurazione delle emissioni
di gas radon e thoron dal suolo effettuate lungo
il fianco orientale dell’Etna, in una zona caratterizzata
dalla presenza di numerose faglie attive.
Le elaborazioni statistiche effettuate hanno
permesso di riconoscere soglie di anomalia
dei dati geochimici, nonché la produzione di
mappe di distribuzione che hanno evidenziato
una significativa correlazione spaziale tra le
anomalie riscontrate e i principali lineamenti
tettonici. Entrambe le anomalie di radon e
thoron si trovavano in aree interessate da sismicitÃ
relativamente profonda, in particolare
in corrispondenza delle zone di intersezione tra
faglie differentemente orientate. Questo studio
conferma che la mappatura della distribuzione
di gas radon e thoron dal suolo può rivelare la
presenza di faglie nascoste da coperture recenti,
o faglie che non sono chiaramente visibili
in superficie
Armazenamento de sementes de Louro-pardo (Cordia trichotoma (VELL.) ARRB. ex STEUD.).
bitstream/item/101584/1/1984-PA17-Zanon-ArmazenamentoSementes0001.pd
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