124 research outputs found
Keypics: free–hand drawn iconic keywords
We propose an iconic indexing of images to be exposed on the Web. This should be accomplished by “Keypics”, i.e. auxiliary, simplified pictures referring to the geometrical and/or the semantic content of the indexed image. Keypics should not be rigidly standardized; they should be left free to evolve, to express nuances and to stress details. A mathematical tool for dealing with such freedom, in the retrieval task, already exists: Size Functions. An experiment on 494 Keypics with Size Functions based on three measuring functions (distances, projections and jumps) and their combination is presented
Approximating the 2-dimensional matching distance
Some new approximation results about the 2-dimensional matching distance are presented, leading to the formulation of an algorithm for its computation (up to an arbitrary input error)
Towards a topological-geometrical theory of group equivariant non-expansive operators for data analysis and machine learning
The aim of this paper is to provide a general mathematical framework for
group equivariance in the machine learning context. The framework builds on a
synergy between persistent homology and the theory of group actions. We define
group-equivariant non-expansive operators (GENEOs), which are maps between
function spaces associated with groups of transformations. We study the
topological and metric properties of the space of GENEOs to evaluate their
approximating power and set the basis for general strategies to initialise and
compose operators. We begin by defining suitable pseudo-metrics for the
function spaces, the equivariance groups, and the set of non-expansive
operators. Basing on these pseudo-metrics, we prove that the space of GENEOs is
compact and convex, under the assumption that the function spaces are compact
and convex. These results provide fundamental guarantees in a machine learning
perspective. We show examples on the MNIST and fashion-MNIST datasets. By
considering isometry-equivariant non-expansive operators, we describe a simple
strategy to select and sample operators, and show how the selected and sampled
operators can be used to perform both classical metric learning and an
effective initialisation of the kernels of a convolutional neural network.Comment: Added references. Extended Section 7. Added 3 figures. Corrected
typos. 42 pages, 7 figure
Approximating the 2-dimensional matching distance
Some new approximation results about the 2-dimensional matching distance are presented, leading to the formulation of an algorithm for its computation (up to an arbitrary input error)
α-Synuclein Heterocomplexes with β-Amyloid Are Increased in Red Blood Cells of Parkinson's Disease Patients and Correlate with Disease Severity
Neurodegenerative disorders (NDs) are characterized by abnormal accumulation/misfolding of specific proteins, primarily α-synuclein (α-syn), β-amyloid1-42(Aβ1-42) and tau, in both brain and peripheral tissues. In addition to oligomers, the role of the interactions of α-syn with Aβ or tau has gradually emerged. Nevertheless, despite intensive research, NDs have no accepted peripheral markers for biochemical diagnosis. In this respect, Red Blood Cells (RBCs) are emerging as a valid peripheral model for the study of aging-related pathologies. Herein, a small cohort (N= 28) of patients affected by Parkinson's disease (PD) and age-matched controls were enrolled to detect the content of α-syn (total and oligomeric), Aβ1-42and tau (total and phosphorylated) in RBCs. Moreover, the presence of α-syn association with tau and Aβ1-42was explored by co-immunoprecipitation/western blotting in the same cells, and quantitatively confirmed by immunoenzymatic assays. For the first time, PD patients were demonstrated to exhibit α-syn heterocomplexes with Aβ1-42and tau in peripheral tissues; interestingly, α-syn-Aβ1-42concentrations were increased in PD subjects with respect to healthy controls (HC), and directly correlated with disease severity and motor deficits. Moreover, total-α-syn levels were decreased in PD subjects and inversely related to their motor deficits. Finally, an increase of oligomeric-α-syn and phosphorylated-tau was observed in RBCs of the enrolled patients. The combination of three parameters (total-α-syn, phosphorylated-tau and α-syn-Aβ1-42concentrations) provided the best fitting predictive index for discriminating PD patients from controls. Nevertheless further investigations should be required, overall, these data suggest α-syn hetero-aggregates in RBCs as a putative tool for the diagnosis of PD
Alexithymia may modulate decision making in patients with de novo Parkinson’s disease
The aim of this study was to investigate whether and
how alexithymia may influence decision making under
conditions of uncertainty, assessed using the Iowa
Gambling Task, in patients with newly diagnosed, untreated
(de novo) Parkinson’s disease, as previously reported
for healthy subjects.
Twenty-four patients with de novo Parkinson’s disease
underwent a neuropsychological and neuropsychiatric
assessment, including the Toronto Alexithymia Scale,
the Geriatric Depression Scale Short Form, and the
Iowa Gambling Task (IGT).
The assessment showed that 12 patients were alexithymic
and 12 were non-alexithymic; seven patients
were found to be mildly depressed and 17 non-depressed.
Alexithymic and non-alexithymic patients did
not differ in the IGT total score; however, significant differences
emerged across the third block of the IGT, in
which the alexithymic patients outperformed the nonalexithymic patients. Depression did not influence IGT
performance.
Alexithymia may modulate decision making, as assessed
with the IGT; alexithymia could be associated with faster learning to avoid risky choices and negative feedback, as previously reported in some studies conducted in anxious or depressed patients
Dopamine Transporter SPECT Imaging in Corticobasal Syndrome
evidence of preserved nigral neuronal density. imaging evidence of preserved nigral terminals have been recently described.In this multicenter study, we investigated presynaptic nigrostriatal function in 36 outpatients fulfilling clinical criteria for “probable corticobasal degeneration” (age 71±7.3 years; disease duration 3.9±1.6 years), 37 PD and 24 healthy control subjects using FP-CIT single photon emission computed tomography. Clinical, neuropsychological, and magnetic resonance imaging assessment was performed to characterize CBS patients. Linear discriminant analysis was used to categorize normal vs. pathological scans.FP-CIT binding reduction in patients with CBS was characterized by larger variability, more uniform reduction throughout the striatum and greater hemispheric asymmetry compared to PD. Moreover, there was no significant correlation between tracer uptake values and clinical features such as disease duration and severity. Despite all CBS subjects showed obvious bilateral extrapyramidal signs, FP-CIT uptake was found to be normal bilaterally in four CBS patients and only unilaterally in other four cases. Extensive clinical, neuropsychological and imaging assessment did not reveal remarkable differences between CBS subjects with normal vs. pathological FP-CIT uptake.Our findings support the hypothesis that extrapyramidal motor symptoms in CBS are not invariably associated with SNc neuronal degeneration and that supranigral factors may play a major role in several cases. CBS individuals with normal FP-CIT uptake do not show any clinical or cognitive feature suggesting a different pathology than CBD
A study of CP violation in B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays with D -> (KSK +/-)-K-0 pi(-/+) final states
A first study of CP violation in the decay modes and , where labels a or meson and labels a or meson, is performed. The analysis uses the LHCb data set collected in collisions, corresponding to an integrated luminosity of 3 fb. The analysis is sensitive to the CP-violating CKM phase through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of using other decay modes
- …