13 research outputs found
Caratteristiche farmacologiche e uso clinico del Palivizumab nel trattamento dellâinfezione dal virus respiratorio sinciziale
Uno dei principali patogeni del tratto inferiore respiratorio nei bambini sotto i 2 anni Ăš il virus respiratorio sinciziale (RSV). Nel 2015 fu stimato dallâOMS che erano presenti circa 64 milioni di infezioni lâanno e 160mila morti in tutto il mondo causate dall' RSV. Il rischio di infezione da RSV Ăš molto alto nei bambini che nascono prematuri o con displasia broncopolmonare (BPD), o con malattie polmonari croniche (CLD), o con malattie congenite cardiache (CHD). La prevenzione si basa sulla profilassi ambientale, rivolta a minimizzare la diffusione del virus e sulla profilassi farmacologica, la quale prevede la somministrazione di Palivizumab ai bambini ad alto rischio durante il periodo epidemico (dicembre-aprile). Il Palivizumab Ăš un'anticorpo monoclonale che lega un epitopo della glicoproteina F presente sulla superficie dellâ RSV andando a bolccare il legame tra il virus e la cellula bersaglio. Questo trattamento diminuisce lâospedalizzazione e la criticitĂ clinica dellâinfezione del 55% nei neonati ad alto rischio. Sfortunatamente, uno dei principali problemi del farmaco Ăš dovuto all'elevato costo di un singolo trattamento, stimato intorno a 4458 $ per bambino. Di conseguenza la somministrazione viene effettuata solamente su un gruppo ristretto di bambini, andandone a limitare gli studi e lâefficacia. Attraverso molto studi si pensa che lâuso del Palivizumab sia sicuramete dâaiuto per neonati prematuri nati prima della 33 settimana
Non-equilibrium effects on charge and energy partitioning after an interaction quench
Charge and energy fractionalization are among the most intriguing features of
interacting onedimensional fermion systems. In this work we determine how these
phenomena are modified in the presence of an interaction quench. Charge and
energy are injected into the system suddenly after the quench, by means of
tunneling processes with a non-interacting one-dimensional probe. Here, we
demonstrate that the system settles to a steady state in which the charge
fractionalization ratio is unaffected by the pre-quenched parameters. On the
contrary, due to the post-quench nonequilibrium spectral function, the energy
partitioning ratio is strongly modified, reaching values larger than one. This
is a peculiar feature of the non-equilibrium dynamics of the quench process and
it is in sharp contrast with the non-quenched case, where the ratio is bounded
by one.Comment: 12 pages, 4 figure
Quench-induced entanglement and relaxation dynamics in Luttinger liquids
We investigate the time evolution towards the asymptotic steady state of a one-dimensional interacting system after a quantum quench. We show that at finite times the latter induces entanglement between right- and left-moving density excitations, encoded in their cross-correlators, which vanishes in the long-time limit. This behavior results in a universal time decay âtâ2 of the system spectral properties, in addition to nonuniversal power-law contributions typical of Luttinger liquids. Importantly, we argue that the presence of quench-induced entanglement clearly emerges in transport properties, such as charge and energy currents injected in the system from a biased probe and determines their long-time dynamics. In particular, the energy fractionalization phenomenon turns out to be a promising platform to observe the universal power-law decay âtâ2 induced by entanglement and represents a novel way to study the corresponding relaxation mechanism
Genome-wide essential gene identification in Streptococcus sanguinis
A clear perception of gene essentiality in bacterial pathogens is pivotal for identifying drug targets to combat emergence of new pathogens and antibiotic-resistant bacteria, for synthetic biology, and for understanding the origins of life. We have constructed a comprehensive set of deletion mutants and systematically identified a clearly defined set of essential genes for Streptococcus sanguinis. Our results were confirmed by growing S. sanguinis in minimal medium and by double-knockout of paralogous or isozyme genes. Careful examination revealed that these essential genes were associated with only three basic categories of biological functions: maintenance of the cell envelope, energy production, and processing of genetic information. Our finding was subsequently validated in two other pathogenic streptococcal species, Streptococcus pneumoniae and Streptococcus mutans and in two other gram-positive pathogens, Bacillus subtilis and Staphylococcus aureus. Our analysis has thus led to a simplified model that permits reliable prediction of gene essentiality
Transport Properties as a Tool to Study Universal Quench-induced Dynamics in 1D Systems
The study of the relaxation process that follows a quantum quench in 1D systems still represents an
open research field. Here we consider a sudden change of the interparticle interaction and we identify a
peculiar correlator of the system whose behavior is directly and deeply affected by the quench-induced
dynamics. Interestingly, it features a universal power-law decay in time. Unfortunately, such a universal
decay, although present, turns out to be subleading in intrinsic properties of the system such as the non-
equilibrium spectral function. We thus consider a tunnel coupling of the system with a biased tip in order
to be able to study also transport properties, namely the charge and energy current flowing from the tip to
the system after the quench. In these quantities the universal power-law emerges clearly, especially if one
focuses on energy current and its fractionalization into a right- and left- moving components. In particular,
we show that the presence of a transient in the energy fractionalization ratio is a direct hallmark of the
quench-induced relaxation. Within the setup we have considered, time-dependent transport properties
are thus promoted to useful and promising tools to access the mechanisms at the base of the out-of-
equilibrium dynamics following quantum quench
Transport properties as a tool to study universal features of quench-induced dynamics in 1D systems
Asymmetries in the spectral density of an interaction-quenched Luttinger liquid
The spectral density of an interaction-quenched one-dimensional system is investigated. Both direct and inverse quench protocols are considered and it is found that the former leads to stronger effects on the spectral density with respect to the latter. Such asymmetry is directly reflected on transport properties of the system, namely the charge and energy current flowing to the system from a tunnel coupled biased probe. In particular, the injection of particles from the probe to the right-moving channel of the system is considered. The resulting fractionalization phenomena are strongly affected by the quench protocol and display asymmetries in the case of direct and inverse quench. Transport properties therefore emerge as natural probes for the observation of this quench-induced behavior
Universal scaling of quench-induced correlations in a one-dimensional channel at finite temperature
It has been shown that a quantum quench of interactions in a one-dimensional
fermion system at zero temperature induces a universal power law in its long-time dynamics. In this paper we demonstrate that this
behaviour is robust even in the presence of thermal effects. The system is
initially prepared in a thermal state, then at a given time the bath is
disconnected and the interaction strength is suddenly quenched. The
corresponding effects on the long times dynamics of the non-equilibrium
fermionic spectral function are considered. We show that the non-universal
power laws, present at zero temperature, acquire an exponential decay due to
thermal effects and are washed out at long times, while the universal behaviour
is always present. To verify our findings, we argue that these
features are also visible in transport properties at finite temperature. The
long-time dynamics of the current injected from a biased probe exhibits the
same universal power law relaxation, in sharp contrast with the non-quenched
case which features a fast exponential decay of the current towards its steady
value, and thus represents a fingerprint of quench-induced dynamics. Finally,
we show that a proper tuning of the probe temperature, compared to that of the
one-dimensional channel, can enhance the visibility of the universal power-law
behaviour