Spontaneous nucleation of structural defects in inhomogeneous ion chains

Structural defects in ion crystals can be formed during a linear quench of the transverse trapping frequency across the mechanical instability from a linear chain to the zigzag structure. The density of defects after the sweep can be conveniently described by the Kibble-Zurek mechanism. In particular, the number of kinks in the zigzag ordering can be derived from a time-dependent Ginzburg-Landau equation for the order parameter, here the zigzag transverse size, under the assumption that the ions are continuously laser cooled. In a linear Paul trap the transition becomes inhomogeneous, being the charge density larger in the center and more rarefied at the edges. During the linear quench the mechanical instability is first crossed in the center of the chain, and a front, at which the mechanical instability is crossed during the quench, is identified which propagates along the chain from the center to the edges. If the velocity of this front is smaller than the sound velocity, the dynamics becomes adiabatic even in the thermodynamic limit and no defect is produced. Otherwise, the nucleation of kinks is reduced with respect to the case in which the charges are homogeneously distributed, leading to a new scaling of the density of kinks with the quenching rate. The analytical predictions are verified numerically by integrating the Langevin equations of motion of the ions, in presence of a time-dependent transverse confinement. We argue that the non-equilibrium dynamics of an ion chain in a Paul trap constitutes an ideal scenario to test the inhomogeneous extension of the Kibble-Zurek mechanism, which lacks experimental evidence to date.Comment: 19 pages, 5 figure

Understanding the production mechanisms of particles with strangeness in pp collisions with the ALICE experiment at the LHC

Heavy-ion collisions are a unique tool to study the quark-gluon plasma (QGP), a state of matter in which quarks and gluons are not bound within hadrons by the strong force. QGP is expected to form when high energy density and temperature conditions are reached, as in heavy-ion collisions. One proposed signature of QGP formation is the strangeness enhancement effect, which consists in an increase of the ratio of strange to non-strange hadron yields in Pb-Pb collisions with respect to minimum bias pp collisions. This effect has been further investigated within the ALICE collaboration by studying its dependence on the multiplicity of charged particles produced in different collision systems. Results show that the ratios of different strange hadron yields to pion yields increase with the multiplicity of charged particles, revealing a smooth transition between different collision systems, from low multiplicity proton-proton (pp) collisions to high multiplicity central Pb-Pb collisions. This behaviour is striking as different particle production mechanisms are expected to be involved in the different collision systems. The work presented in this thesis addresses the strangeness enhancement observed in pp collisions, focusing on the production of the strange meson K^0_S and of the strange baryon \Xi^\pm in jets and out of jets in pp collisions at \sqrt{s}=5.02 TeV and at \sqrt{s}=13 TeV. The data were collected by the ALICE experiment during the Run 2 data taking. The aim of this work is to evaluate the contribution to the strangeness enhancement effect given by the mechanisms associated with hadron production in jets (hard processes) and out of jets. For the purpose of separating K^0_S (\Xi^\pm) produced in jets from the ones produced out of jets, the angular correlation between the charged particle with the highest transverse momentum p_T and with p_T > 3 GeV/c (trigger particle) and the \Ks (\Xi^\pm) produced in the same collision is evaluated. The trigger particle is considered as a proxy for the jet axis: K^0_S (\Xi^\pm) produced in the leading jet are found in an angular region centred in the direction of the trigger particle (toward-leading production), whereas K^0_S (\Xi^\pm) produced in an angular region transverse to the trigger particle direction are associated to out-of-jet (transverse-to-leading) production. For both K^0_S and \Xi^\pm, the transverse-to-leading yield increases with the multiplicity of charged particles faster than the toward-leading one, suggesting that the relative contribution of transverse-to-leading processes with respect to toward-leading processes increases with the multiplicity of charged particles produced in the collision. The ratio between the \Xi^\pm and the K^0_S yields provides insight into the strangeness enhancement effect, since the strangeness content of the \Xi^\pm is larger than the K^0_S one. Both the transverse-to-leading and the toward-leading \Xi^\pm/K^0_S yield ratios increase with the multiplicity of charged particles. The transverse-to-leading ratio is larger than the toward-leading one, suggesting that the relative production of \Xi^\pm with respect to K^0_S is favoured in transverse-to-leading processes. The results as a function of the charged particle multiplicity are compared with the predictions of different phenomenological models, namely EPOS LHC and two different implementations of PYTHIA8. In the last part of this thesis the further developments of this work which will be possible thanks to the large amount of pp collisions which will be collected during the Run 3 data taking are also discussed.Heavy-ion collisions are a unique tool to study the quark-gluon plasma (QGP), a state of matter in which quarks and gluons are not bound within hadrons by the strong force. QGP is expected to form when high energy density and temperature conditions are reached, as in heavy-ion collisions. One proposed signature of QGP formation is the strangeness enhancement effect, which consists in an increase of the ratio of strange to non-strange hadron yields in Pb-Pb collisions with respect to minimum bias pp collisions. This effect has been further investigated within the ALICE collaboration by studying its dependence on the multiplicity of charged particles produced in different collision systems. Results show that the ratios of different strange hadron yields to pion yields increase with the multiplicity of charged particles, revealing a smooth transition between different collision systems, from low multiplicity proton-proton (pp) collisions to high multiplicity central Pb-Pb collisions. This behaviour is striking as different particle production mechanisms are expected to be involved in the different collision systems. The work presented in this thesis addresses the strangeness enhancement observed in pp collisions, focusing on the production of the strange meson K^0_S and of the strange baryon \Xi^\pm in jets and out of jets in pp collisions at \sqrt{s}=5.02 TeV and at \sqrt{s}=13 TeV. The data were collected by the ALICE experiment during the Run 2 data taking. The aim of this work is to evaluate the contribution to the strangeness enhancement effect given by the mechanisms associated with hadron production in jets (hard processes) and out of jets. For the purpose of separating K^0_S (\Xi^\pm) produced in jets from the ones produced out of jets, the angular correlation between the charged particle with the highest transverse momentum p_T and with p_T > 3 GeV/c (trigger particle) and the \Ks (\Xi^\pm) produced in the same collision is evaluated. The trigger particle is considered as a proxy for the jet axis: K^0_S (\Xi^\pm) produced in the leading jet are found in an angular region centred in the direction of the trigger particle (toward-leading production), whereas K^0_S (\Xi^\pm) produced in an angular region transverse to the trigger particle direction are associated to out-of-jet (transverse-to-leading) production. For both K^0_S and \Xi^\pm, the transverse-to-leading yield increases with the multiplicity of charged particles faster than the toward-leading one, suggesting that the relative contribution of transverse-to-leading processes with respect to toward-leading processes increases with the multiplicity of charged particles produced in the collision. The ratio between the \Xi^\pm and the K^0_S yields provides insight into the strangeness enhancement effect, since the strangeness content of the \Xi^\pm is larger than the K^0_S one. Both the transverse-to-leading and the toward-leading \Xi^\pm/K^0_S yield ratios increase with the multiplicity of charged particles. The transverse-to-leading ratio is larger than the toward-leading one, suggesting that the relative production of \Xi^\pm with respect to K^0_S is favoured in transverse-to-leading processes. The results as a function of the charged particle multiplicity are compared with the predictions of different phenomenological models, namely EPOS LHC and two different implementations of PYTHIA8. In the last part of this thesis the further developments of this work which will be possible thanks to the large amount of pp collisions which will be collected during the Run 3 data taking are also discussed

Representation of others’ synchronous and asynchronous sentences interferes with sentence production

In dialogue, people represent each other's utterances in order to take turns and communicate successfully. In previous work Gambi, C., Van de Cavey, J., \& Pickering, M. J. (2015). Interference in joint picture naming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 41(1), 1-21., speakers who were naming single pictures or picture pairs represented whether another speaker was engaged in the same task (versus a different or no task) concurrently, but did not represent in detail the content of the other speaker's utterance. Here, we investigate co-representation of whole sentences. In three experiments, pairs of speakers imagined each other producing active or passive descriptions of transitive events. Speakers took longer to begin speaking when they believed their partner was also preparing to speak, compared to when they did not. Interference occurred when speakers believed their partners were preparing to speak at the same time as them (synchronous production and co-representation; Experiment 1), and also when speakers believed that their partner would speak only after them (asynchronous production and co-representation; Experiments 2a and 2b). However, interference was generally no greater when speakers believed their partner was preparing a different compared to a similar utterance, providing no consistent evidence that speakers represented what their partners were preparing to say. Taken together, these findings indicate that speakers can represent another's intention to speak even as they are themselves preparing to speak, but that such representation tends to lack detail

Interference in Joint Picture Naming

In 4 experiments we showed that picture naming latencies are affected by beliefs about the task concurrently performed by another speaker. Participants took longer to name pictures when they believed that their partner concurrently named pictures than when they believed their partner was silent (Experiments 1 and 4) or concurrently categorized the pictures as being from the same or from different semantic categories (Experiment 2). However, picture naming latencies were not affected by beliefs about what one's partner said, as it did not matter whether participants believed their partner produced the same utterance, or an utterance that differed by ordering (Experiments 1 and 2) or lexical content (Experiments 3 and 4). These findings are consistent with the proposal that speakers represent whether another speaker is preparing to speak but not what they are preparing to say

Immunomodulatory properties of mesenchymal stem cells : a review based on an interdisciplinary meeting held at the Kennedy Institute of Rheumatology Division, London, UK, 31 October 2005

Peer reviewedPublisher PD

IKZF1 Deletions with COBL Breakpoints Are Not Driven by RAG-Mediated Recombination Events in Acute Lymphoblastic Leukemia

IKZF1 deletion (ΔIKZF1) is an important predictor of relapse in both childhood and adult B-cell precursor acute lymphoblastic leukemia (B-ALL). Previously, we revealed that COBL is a hotspot for breakpoints in leukemia and could promote IKZF1 deletions. Through an international collaboration, we provide a detailed genetic and clinical picture of B-ALL with COBL rearrangements (COBL-r). Patients with B-ALL and IKZF1 deletion (n = 133) were included. IKZF1 ∆1-8 were associated with large alterations within chromosome 7: monosomy 7 (18%), isochromosome 7q (10%), 7p loss (19%), and interstitial deletions (53%). The latter included COBL-r, which were found in 12% of the IKZF1 ∆1-8 cohort. Patients with COBL-r are mostly classified as intermediate cytogenetic risk and frequently harbor ETV6, PAX5, CDKN2A/B deletions. Overall, 56% of breakpoints were located within COBL intron 5. Cryptic recombination signal sequence motifs were broadly distributed within the sequence of COBL, and no enrichment for the breakpoint cluster region was found. In summary, a diverse spectrum of alterations characterizes ΔIKZF1 and they also include deletion breakpoints within COBL. We confirmed that COBL is a hotspot associated with ΔIKZF1, but these rearrangements are not driven by RAG-mediated recombination

Unifying darko-lepto-genesis with scalar triplet inflation

We present a scalar triplet extension of the standard model to unify the origin of inflation with neutrino mass, asymmetric dark matter and leptogenesis. In presence of non-minimal couplings to gravity the scalar triplet, mixed with the standard model Higgs, plays the role of inflaton in the early Universe, while its decay to SM Higgs, lepton and dark matter simultaneously generate an asymmetry in the visible and dark matter sectors. On the other hand, in the low energy effective theory the induced vacuum expectation value of the triplet gives sub-eV Majorana masses to active neutrinos. We investigate the model parameter space leading to successful inflation as well as the observed dark matter to baryon abundance. Assuming the standard model like Higgs mass to be at 125-126 GeV, we found that the mass scale of the scalar triplet to be ~ O(10^9) GeV and its trilinear coupling to doublet Higgs is ~ 0.09 so that it not only evades the possibility of having a metastable vacuum in the standard model, but also lead to a rich phenomenological consequences as stated above. Moreover, we found that the scalar triplet inflation strongly constrains the quartic couplings, while allowing for a wide range of Yukawa couplings which generate the CP asymmetries in the visible and dark matter sectors.Comment: (v1) 29 pages, 11 figures; (v2) 30 pages, 1 figure added and discussions expanded, to appear in Nuclear Physics

Micro-rheological properties of lung homogenates correlate with infection severity in a mouse model of Pseudomonas aeruginosa lung infection

Lung infections caused by Pseudomonas aeruginosa pose a serious threat to patients suffering from, among others, cystic fibrosis, chronic obstructive pulmonary disease, or bronchiectasis, often leading to life-threatening complications. The establishment of a chronic infection is substantially related to communication between bacteria via quorum-sensing networks. In this study, we aimed to assess the role of quorum-sensing signaling molecules of the Pseudomonas quinolone signal (PQS) and to investigate the viscoelastic properties of lung tissue homogenates of PA-infected mice in a prolonged acute murine infection model. Therefore, a murine infection model was successfully established via intra-tracheal infection with alginate-supplemented Pseudomonas aeruginosa NH57388A. Rheological properties of lung homogenates were analyzed with multiple particle tracking (MPT) and quorum-sensing molecules were quantified with LC–MS/MS. Statistical analysis of bacterial load and quorum-sensing molecules showed a strong correlation between these biomarkers in infected lungs. This was accompanied by noticeable changes in the consistency of lung homogenates with increasing infection severity. Furthermore, viscoelastic properties of the lung homogenates strongly correlated with bacterial load and quorum sensing molecules. Considering the strong correlation between the viscoelasticity of lung homogenates and the aforementioned biomarkers, the viscoelastic properties of infected lungs might serve as reliable new biomarker for the evaluation of the severity of P. aeruginosa infections in murine models

Benefit-risk profile of cytoreductive drugs along with antiplatelet and antithrombotic therapy after transient ischemic attack or ischemic stroke in myeloproliferative neoplasms

We analyzed 597 patients with myeloproliferative neoplasms (MPN) who presented transient ischemic attacks (TIA, n = 270) or ischemic stroke (IS, n = 327). Treatment included aspirin, oral anticoagulants, and cytoreductive drugs. The composite incidence of recurrent TIA and IS, acute myocardial infarction (AMI), and cardiovascular (CV) death was 4.21 and 19.2%, respectively at one and five years after the index event, an estimate unexpectedly lower than reported in the general population. Patients tended to replicate the first clinical manifestation (hazard ratio, HR: 2.41 and 4.41 for recurrent TIA and IS, respectively); additional factors for recurrent TIA were previous TIA (HR: 3.40) and microvascular disturbances (HR: 2.30); for recurrent IS arterial hypertension (HR: 4.24) and IS occurrence after MPN diagnosis (HR: 4.47). CV mortality was predicted by age over 60 years (HR: 3.98), an index IS (HR: 3.61), and the occurrence of index events after MPN diagnosis (HR: 2.62). Cytoreductive therapy was a strong protective factor (HR: 0.24). The rate of major bleeding was similar to the general population (0.90 per 100 patient-years). In conclusion, the long-term clinical outcome after TIA and IS in MPN appears even more favorable than in the general population, suggesting an advantageous benefit-risk profile of antithrombotic and cytoreductive treatment