609 research outputs found
Asymmetries in symmetric quantum walks on two-dimensional networks
We study numerically the behavior of continuous-time quantum walks over
networks which are topologically equivalent to square lattices. On short time
scales, when placing the initial excitation at a corner of the network, we
observe a fast, directed transport through the network to the opposite corner.
This transport is not ballistic in nature, but rather produced by quantum
mechanical interference. In the long time limit, certain walks show an
asymmetric limiting probability distribution; this feature depends on the
starting site and, remarkably, on the precise size of the network. The limiting
probability distributions show patterns which are correlated with the initial
condition. This might have consequences for the application of continuous time
quantum walk algorithms.Comment: 9 pages, 12 figures, revtex
Dynamics of continuous-time quantum walks in restricted geometries
We study quantum transport on finite discrete structures and we model the
process by means of continuous-time quantum walks. A direct and effective
comparison between quantum and classical walks can be attained based on the
average displacement of the walker as a function of time. Indeed, a fast growth
of the average displacement can be advantageously exploited to build up
efficient search algorithms. By means of analytical and numerical
investigations, we show that the finiteness and the inhomogeneity of the
substrate jointly weaken the quantum walk performance. We further highlight the
interplay between the quantum-walk dynamics and the underlying topology by
studying the temporal evolution of the transfer probability distribution and
the lower bound of long time averages.Comment: 25 pages, 13 figure
Quantum transport on two-dimensional regular graphs
We study the quantum-mechanical transport on two-dimensional graphs by means
of continuous-time quantum walks and analyse the effect of different boundary
conditions (BCs). For periodic BCs in both directions, i.e., for tori, the
problem can be treated in a large measure analytically. Some of these results
carry over to graphs which obey open boundary conditions (OBCs), such as
cylinders or rectangles. Under OBCs the long time transition probabilities
(LPs) also display asymmetries for certain graphs, as a function of their
particular sizes. Interestingly, these effects do not show up in the marginal
distributions, obtained by summing the LPs along one direction.Comment: 22 pages, 11 figure, acceted for publication in J.Phys.
Efficacy of the cdk4/6 dual inhibitor abemaciclib in egfr-mutated nsclc cell lines with different resistance mechanisms to osimertinib
Abemaciclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6 that inhibits the transition from the G1 to the S phase of the cell cycle by blocking downstream CDK4/6-mediated phosphorylation of Rb. The effects of abemaciclib alone or combined with the third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib were examined in a panel of PC9 and HCC827 osimertinib-resistant non-small cell lung cancer (NSCLC) cell lines carrying EGFR-dependent or-independent mechanisms of intrinsic or acquired resistance. Differently from sensitive cells, all the resistant cell lines analyzed maintained p-Rb, which may be considered as a biomarker of osimertinib resistance and a potential target for therapeutic intervention. In these models, abemaciclib inhibited cell growth, spheroid formation, colony formation, and induced senes-cence, and its efficacy was not enhanced in the presence of osimertinib. Interestingly, in osimertinib sensitive PC9, PC9T790M, and H1975 cells the combination of abemaciclib with osimertinib significantly inhibited the onset of resistance in long-term experiments. Our findings provide a preclinical support for using abemaciclib to treat resistance in EGFR mutated NSCLC patients progressed to osimertinib either as single treatment or combined with osimertinib, and suggest the combination of osimertinib with abemaciclib as a potential approach to prevent or delay osimertinib resistance in first-line treatment
Application of CRISPR/Cas9 editing and digital droplet PCR in human iPSCs to generate novel knock-in reporter lines to visualize dopaminergic neurons
Human induced pluripotent stem cells (hiPSCs) have become indispensable for disease modelling. They are an important resource to access patient cells harbouring disease-causing mutations. Derivation of midbrain dopaminergic (DAergic) neurons from hiPSCs of PD patients represents the only option to model physiological processes in a cell type that is not otherwise accessible from human patients. However, differentiation does not produce a homogenous population of DA neurons and contaminant cell types may interfere with the readout of the in vitro system. Here, we use CRISPR/Cas9 to generate novel knock-in reporter lines for DA neurons, engineered with an endogenous fluorescent tyrosine hydroxylase \u2013 enhanced green fluorescent protein (TH-eGFP) reporter. We present a reproducible knock-in strategy combined with a highly specific homologous directed repair (HDR) screening approach using digital droplet PCR (ddPCR). The knock-in cell lines that we created show a functioning fluorescent reporter system for DA neurons that are identifiable by flow cytometry
Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders
Non Celiac Gluten sensitivity (NCGS) was originally described in the 1980s and recently a âre-discoveredâ disorder characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected with either celiac disease (CD) or wheat allergy (WA). Although NCGS frequency is still unclear, epidemiological data have been generated that can help establishing the magnitude of the problem. Clinical studies further defined the identity of NCGS and its implications in human disease. An overlap between the irritable bowel syndrome (IBS) and NCGS has been detected, requiring even more stringent diagnostic criteria. Several studies suggested a relationship between NCGS and neuropsychiatric disorders, particularly autism and schizophrenia. The first case reports of NCGS in children have been described. Lack of biomarkers is still a major limitation of clinical studies, making it difficult to differentiate NCGS from other gluten related disorders. Recent studies raised the possibility that, beside gluten, wheat amylase-trypsin inhibitors and low-fermentable, poorly-absorbed, short-chain carbohydrates can contribute to symptoms (at least those related to IBS) experienced by NCGS patients. In this paper we report the major advances and current trends on NCG
Ecosistemi di acque interne e di transizione
In questo contributo la vulnerabilitĂ degli ecosistemi acquatici ai cambiamenti climatici Ăš analizzata in relazione ai meccanismi di organizzazione e mantenimento della biodiversitĂ e dei processi ecosistemici. Dai processi degli ecosistemi derivano funzioni che forniscono una serie di benefici o servizi per il genere umano (Daily et al., 2009). Tali servizi sono in larga misura
dipendenti dalle componenti biologiche degli ecosistemi86. Negli ecosistemi acquatici i processi biogeochimici (ad es. denitrificazione batterica e assimilazione da parte della vegetazione acquatica), garantiscono lâabbattimento dei nutrienti, una funzione ecosistemica che produce il servizio di depurazione dellâacqua. Altri servizi sono la laminazione delle piene, la ricarica degli acquiferi, la regolazione del microclima locale, la produzione di risorse alimentari quali pesci, crostacei, ecc. (Jones, 2013). Le alterazioni degli ecosistemi, in particolare la perdita di specie e la diminuzione della biodiversitĂ danneggiano questi servizi, con ricadute anche di tipo economico(si pensi, ad esempio, ai costi della depurazione dellâacqua destinata al consumo umano)
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