130 research outputs found

    Weighted inequalities for commutators of Schr\"odinger-Riesz transforms

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    In this work we obtain weighted LpL^p, 1<p<∞1<p<\infty, and weak Llog⁡LL\log L estimates for the commutator of the Riesz transforms associated to a Schr\"odinger operator -\lap+V, where VV satisfies some reverse H\"older inequality. The classes of weights as well as the classes of symbols are larger than ApA_p and BMOBMO corresponding to the classical Riesz transforms

    Weighted inequalities for negative powers of Schrödinger operators

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    AbstractIn this article we obtain boundedness of the operator (−Δ+V)−α/2 from Lp,∞(w) into weighted bounded mean oscillation type spaces BMOLÎČ(w) under appropriate conditions on the weight w. We also show that these weighted spaces also have a point-wise description for 0<ÎČ<1. Finally, we study the behaviour of the operator (−Δ+V)−α/2 when acting on BMOLÎČ(w)

    Frontostriatal deficit in Motor Neuron Disease/Amyotrophic Lateral Sclerosis (MND/ALS)

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    So far, cognitive derangements in MND/ALS have not been widely studied. Nevertheless, it seems that in subgroups of patients cognitive functions are impaired in different degree, so that often at least two sub-types of the syndrome are reported: Motor Neuron Disease/Amyotrophic Lateral Sclerosis/Dementia Syndrome (MND/ALS/DS) and Motor Neuron Disease/Amyotrophic Lateral Sclerosis/ Aphasia Syndrome (MND/ALS/AS. A third subtype showing both symptoms of cognitive impairment may be identified in subgroups of patients and denominated Motor Neuron Disease/Amyotrophic Lateral Sclerosis/Dementia-Aphasia Syndrome (MND/ALS/DAS). Frontostriatal system is reported as a network heavily damaged in MND/ALS/DS, MND/ALS/AS, MND/ALS/DAS. The system is plausibly responsible of motor skills and verbs production, hence to become aware of a possible frontostriatal deficit in subgroup of MND/ALS patients might consent us to link at the brain level (motor) action and verbs and possibly ideomotor praxia and verbs. We have used Goal-Oriented Perception Task (GOPT) and Action Fluency Task (AFT) in order to detect with some accuracy impairments related to gestaltic analysis directed toward a goal, and verb retrieval deficits possibly underlying executive system dysfunction that destabilizes the ability to mentally coordinate the information associated with a verb. These tests should consent to detect possible frontostriatal derangements. We have tested 10 MND/ALS patients and 10 healthy subjects matched fore age, sex and laterality. AFT showed that 3 out of 6 patients are heavily impaired in this test (6.3 (mean) verbs generated vs 13.3 of the control group). GOPT detected a remarkable impairment in all patients: p=0.0021 (grammatical side), p=0.0002 (perceptual side). Reported frontostriatal deficit in MND/ALS seems confirmed by this study, and probably it is more easily detected by GOPT than by AFT

    VGF peptides as novel biomarkers in Parkinson’s disease

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    Parkinson’s disease (PD) is characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra (SN). At disease onset, a diagnosis is often difficult. VGF peptides are abundant in the SN and peripheral circulation; hence, we investigate whether their plasma profile may reflect the brain dopamine reduction. Using antibodies against the VGF C-terminal portion, we analyzed the rat brain and human plasma, with immunohistochemistry and ELISA. Rats were unilaterally lesioned with 6-hyroxydopamine and sacrificed either 3 or 6 weeks later with or without levodopa treatment. Plasma samples were obtained from PD patients, either at the time of diagnosis (group 1, drug naĂŻve, n = 23) or upon dopamine replacement (group 2, 1–6 years, n = 24; group 3, &gt; 6 years, n = 16), compared with age-matched control subjects (group 4, n = 21). Assessment of the olfactory function was carried out in group 2 using the “Sniffin’ Sticks” test. VGF immunoreactivity was present in GABAergic neurons and, on the lesioned side, it was reduced at 3 weeks and abolished at 6 weeks after lesion. Conversely, upon levopoda, VGF labeling was restored. In PD patients, VGF levels were reduced at the time of diagnosis (1504 ± 587 vs. 643 ± 348 pmol/mL, means ± S.E.M: control vs. naĂŻve; p &lt; 0.05) but were comparable with the controls after long-term drug treatment (&gt; 6 years). A linear correlation was demonstrated between VGF immunoreactivity and disease duration, levodopa equivalent dose and olfactory dysfunction. Plasma VGF levels may represent a useful biomarker, especially in the early stages of PD

    Integrated photonic quantum gates for polarization qubits

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    Integrated photonic circuits have a strong potential to perform quantum information processing. Indeed, the ability to manipulate quantum states of light by integrated devices may open new perspectives both for fundamental tests of quantum mechanics and for novel technological applications. However, the technology for handling polarization encoded qubits, the most commonly adopted approach, is still missing in quantum optical circuits. Here we demonstrate the first integrated photonic Controlled-NOT (CNOT) gate for polarization encoded qubits. This result has been enabled by the integration, based on femtosecond laser waveguide writing, of partially polarizing beam splitters on a glass chip. We characterize the logical truth table of the quantum gate demonstrating its high fidelity to the expected one. In addition, we show the ability of this gate to transform separable states into entangled ones and vice versa. Finally, the full accessibility of our device is exploited to carry out a complete characterization of the CNOT gate through a quantum process tomography.Comment: 6 pages, 4 figure

    The Effect of Service on Research Performance: A Study on Italian Academics in Management

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    Academics all over the world are feeling the increasing pressure to attain satisfactory research performance. Since research is not the only activity required of academics, though, the debate on how it may be coupled with other knowledge transfer activities like teaching, patenting, and dissemination has been captivating scholars interested in higher education. Literature is surprisingly silent about the interplay between research performance and other roles and tasks that faculty are expected to carry out, namely academic citizenship, intended as the service that they provide to their institution, to the scientific community, and to the larger society. Through a negative binomial regression conducted on 692 Italian academics in management, this paper investigates both the direct and moderating effect exerted by academic citizenship on the relationship between research performance in two subsequent evaluation exercises, thus advancing our knowledge of the relationship between research and service. Findings show that institutional service acts as a pure moderator, discipline-based service is a quasi-moderator, while public service exerts only a direct negative effect on research performance. In light of the emergent interplay between research and service, the necessity to boost reflection on academic citizenship is discussed and suggestions for its acknowledgement and advancement are formulated

    No evidence of association between prothrombotic gene polymorphisms and the development of acute myocardial infarction at a young age

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    Background : we investigated the association between 9 polymorphisms of genes encoding hemostasis factors and myocardial infarction in a large sample of young patients chosen because they have less coronary atherosclerosis than older patients, and thus their disease is more likely to be related to a genetic predisposition to a prothrombotic state Methods and Results : this nationwide case-control study involved 1210 patients who had survived a first myocardial infarction at an age of 45 years who underwent coronary arteriography in 125 coronary care units and 1210 healthy subjects matched for age, sex, and geographical origin. None of the 9 polymorphisms of genes encoding proteins involved in coagulation (G-455A -fibrinogen: OR, 1.0; CI, 0.8 to 1.2; G1691A factor V: OR, 1.1; CI, 0.6 to 2.1; G20210A factor II: OR, 1.0; CI, 0.5 to 1.9; and G10976A factor VII: OR, 1.0; CI, 0.8 to 1.3), platelet function (C807T glycoprotein Ia: OR, 1.1; CI, 0.9 to 1.3; and C1565T glycoprotein IIIa: OR, 0.9; CI, 0.8 to 1.2), fibrinolysis (G185T factor XIII: OR, 1.2; CI, 0.9 to 1.6; and 4G/5G plasminogen activator inhibitor type 1: OR, 0.9; CI, 0.7 to 1.2), or homocysteine metabolism (C677T methylenetetrahydrofolate reductase: OR, 0.9; CI, 0.8 to 1.1) were associated with an increased or decreased risk of myocardial infarction Conclusions : this study provides no evidence supporting an association between 9 polymorphisms of genes encoding proteins involved in hemostasis and the occurrence of premature myocardial infarction or protection against it
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