939 research outputs found
Childhood polycythemia vera and essential thrombocythemia: Does their pathogenesis overlap with that of adult patients?
[No abstract available
The Role of physical activity and nutrition in the sarcopenia of cirrhosis.
The aim of this review is to understand how physical activity and nutrition are involved in the improvement of sarcopenia in patients affected by liver cirrhosis. The pathogenesis of sarcopenia in cirrhosis involves three major factors: inadequate dietary intake, metabolic disturbances, and malabsorption. Although in the early stages muscles appear to be spared, sarcopenia progressively leads to mobility limitations and its consequences, such as propensity to falls and drastically reducing life quality. Several studies confirm the important role played by physical activity and balanced nutrition in this chronic condition. Exercise and nutritional intervention should be recommended in these patients in order to improve quality of life
Showcasing a Barren Plateau Theory Beyond the Dynamical Lie Algebra
Barren plateaus have emerged as a pivotal challenge for variational quantum
computing. Our understanding of this phenomenon underwent a transformative
shift with the recent introduction of a Lie algebraic theory capable of
explaining most sources of barren plateaus. However, this theory requires
either initial states or observables that lie in the circuit's Lie algebra.
Focusing on parametrized matchgate circuits, in this work we are able to go
beyond this assumption and provide an exact formula for the loss function
variance that is valid for arbitrary input states and measurements. Our results
reveal that new phenomena emerge when the Lie algebra constraint is relaxed.
For instance, we find that the variance does not necessarily vanish inversely
with the Lie algebra's dimension. Instead, this measure of expressiveness is
replaced by a generalized expressiveness quantity: The dimension of the Lie
group modules. By characterizing the operators in these modules as products of
Majorana operators, we can introduce a precise notion of generalized globality
and show that measuring generalized-global operators leads to barren plateaus.
Our work also provides operational meaning to the generalized entanglement as
we connect it with known fermionic entanglement measures, and show that it
satisfies a monogamy relation. Finally, while parameterized matchgate circuits
are not efficiently simulable in general, our results suggest that the
structure allowing for trainability may also lead to classical simulability.Comment: 5+26 pages, 2+1 figure
Lipid Exchange between Borrelia burgdorferi and Host Cells
Borrelia burgdorferi, the agent of Lyme disease, has cholesterol and cholesterol-glycolipids that are essential for bacterial fitness, are antigenic, and could be important in mediating interactions with cells of the eukaryotic host. We show that the spirochetes can acquire cholesterol from plasma membranes of epithelial cells. In addition, through fluorescent and confocal microscopy combined with biochemical approaches, we demonstrated that B. burgdorferi labeled with the fluorescent cholesterol analog BODIPY-cholesterol or 3H-labeled cholesterol transfer both cholesterol and cholesterol-glycolipids to HeLa cells. The transfer occurs through two different mechanisms, by direct contact between the bacteria and eukaryotic cell and/or through release of outer membrane vesicles. Thus, two-way lipid exchange between spirochetes and host cells can occur. This lipid exchange could be an important process that contributes to the pathogenesis of Lyme disease
Earth conductivity structures and their effects on geomagnetic induction in pipelines
Anomalous, large pipe-to-soil potentials (PSP) have been observed along a natural gas pipeline in eastern Ontario, Canada, where there is a major geological contact between the highly resistive rocks of the Precambrian Shield to the west and the more conductive Paleozoic sediments to the east. This study tested the hypothesis that large variations of PSP are related to lateral changes of Earth conductivity under the pipeline. Concurrent and co-located PSP and magnetotelluric (MT) geophysical data were acquired in the study area. Results from the MT survey were used to model PSP variations based on distributed-source transmission line theory, using a spatially-variant surface geoelectric field. Different models were built to investigate the impact of different subsurface features. Good agreement between modelled and observed PSP was reached when impedance peaks related to major changes of subsurface geological conditions were included. The large PSP could therefore be attributed to the presence of resistive intrusive bodies in the upper crust and/or boundaries between tectonic terranes. This study demonstrated that combined PSP-MT investigations are a useful tool in the identification of potential hazards caused by geomagnetically induced currents in pipelines
Parallel-in-time quantum simulation via Page and Wootters quantum time
In the past few decades, researchers have created a veritable zoo of quantum
algorithm by drawing inspiration from classical computing, information theory,
and even from physical phenomena. Here we present quantum algorithms for
parallel-in-time simulations that are inspired by the Page and Wooters
formalism. In this framework, and thus in our algorithms, the classical
time-variable of quantum mechanics is promoted to the quantum realm by
introducing a Hilbert space of "clock" qubits which are then entangled with the
"system" qubits. We show that our algorithms can compute temporal properties
over different times of many-body systems by only using clock
qubits. As such, we achieve an exponential trade-off between time and spatial
complexities. In addition, we rigorously prove that the entanglement created
between the system qubits and the clock qubits has operational meaning, as it
encodes valuable information about the system's dynamics. We also provide a
circuit depth estimation of all the protocols, showing an exponential advantage
in computation times over traditional sequential in time algorithms. In
particular, for the case when the dynamics are determined by the Aubry-Andre
model, we present a hybrid method for which our algorithms have a depth that
only scales as . As a by product we can relate the
previous schemes to the problem of equilibration of an isolated quantum system,
thus indicating that our framework enable a new dimension for studying
dynamical properties of many-body systems.Comment: 19+15 pages, 18+1 figure
Installazione di un radiometro nell'area sommitale del vulcano Etna
Le tecniche di telerilevamento satellitare e da terra per la stima della temperatura di anomalie termiche
delle superfici vulcaniche, della loro variazione nel tempo e per individuare attività parossistiche o l’inizio di
una fase di colate di lava, sono ormai entrate a far parte della sorveglianza e del monitoraggio vulcanologico
[es. Francis, 1979; Geraci et al., 1985; Lombardo et al., 2011; Spampinato et al., 2011]. I sensori in una
banda spettrale dell’infrarosso quali radiometri e telecamere termiche, utilizzati in prossimità di bocche
eruttive, hanno fornito cospicue quantità di dati di temperatura della superficie di corpi magmatici (colate
laviche, laghi di lava, duomi lavici), plume vulcanici, fumarole, registrati a distanza di totale sicurezza
[Spampinato et al., 2011]. In particolare, i radiometri, sia portatili che installati in stazioni permanenti, oltre
che fornire dati da confrontare con misure geochimiche, permettono l’acquisizione di dati di temperatura ad
elevata frequenza, tali da essere messi in relazione con le misure derivate da osservazioni geofisiche quali ad
esempio il tremore sismico [es. Harris e Ripepe, 2007; Branan et al., 2008].In questo lavoro si descrivono i dettagli dell’installazione di una stazione radiometrica collocata
nell’area sommitale dell’Etna in zona Belvedere, nel sito già utilizzato da una stazione multiparametrica (con
sensori sismici e infrasonici) e denominato EBEL. Si descrivono anche la metodologia di trasmissione dati in
continuo, il trattamento del dato convertito in temperatura apparente nel campo di vista del radiometro, la
visualizzazione in tempo quasi reale del dato e la sua diffusione tramite WEB
Fiber Optic Cable Thermal Preparation to Ensure Stable Operation
Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50 C up to 125 C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission
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