4,215 research outputs found
A Syntactic Model of Mutation and Aliasing
Traditionally, semantic models of imperative languages use an auxiliary
structure which mimics memory. In this way, ownership and other encapsulation
properties need to be reconstructed from the graph structure of such global
memory. We present an alternative "syntactic" model where memory is encoded as
part of the program rather than as a separate resource. This means that
execution can be modelled by just rewriting source code terms, as in semantic
models for functional programs. Formally, this is achieved by the block
construct, introducing local variable declarations, which play the role of
memory when their initializing expressions have been evaluated. In this way, we
obtain a language semantics which directly represents at the syntactic level
constraints on aliasing, allowing simpler reasoning about related properties.
To illustrate this advantage, we consider the issue, widely studied in the
literature, of characterizing an isolated portion of memory, which cannot be
reached through external references. In the syntactic model, closed block
values, called "capsules", provide a simple representation of isolated portions
of memory, and capsules can be safely moved to another location in the memory,
without introducing sharing, by means of "affine' variables. We prove that the
syntactic model can be encoded in the conventional one, hence efficiently
implemented.Comment: In Proceedings DCM 2018 and ITRS 2018 , arXiv:1904.0956
The Dark Side of Study: When Study Negatively Affects Relationships and School Climate. The Study-Relationships Conflict Scale
This study proposes a new instrument for evaluating the Study-Relationships Conflict, or the conflict that may exist between study and personal relationships with family, friends, schoolmates, and teachers. We recruited a sample of 598 Italian University students (age: M = 22.58 ± 3.85) of different majors. By means of Exploratory and Confirmatory Factor Analyses, we reduced the 16-item pilot version to nine items and three factors: 1) Quarrels at School—QS; 2) Relationship Impairment—RI; 3) Family and Friends' Complaints—FFC. Moreover, we analyzed the correlation between these scales and some academic indicators: Grade Point Average (GPA) and time spent studying. The results showed that the Study-Relationships Conflict Scale (SRCS) has good psychometric properties. In addition, GPA positively correlates with the FFC scale; while time spent studying correlates positively with both the RI and the FFC scales. Finally, QS has a statistically and low significant positive correlation with the hours a day of study before exams. The SRCS will be useful in future research aiming to analyze how studying behaviors could affect social and school relationships. Moreover, it could also be used as a quick screening for detecting student at-risk of high social impairment due to their overstudying, and for developing preventive interventions
Investigation of adaptive optics imaging biomarkers for detecting pathological changes of the cone mosaic in patients with type 1 diabetes mellitus
Purpose
To investigate a set of adaptive optics (AO) imaging biomarkers for the assessment of
changes of the cone mosaic spatial arrangement in patients with type 1 diabetes mellitus
(DM1).
Methods
16 patients with 20/20 visual acuity and a diagnosis of DM1 in the past 8 years to 37 years
and 20 age-matched healthy volunteers were recruited in this study. Cone density, cone
spacing and Voronoi diagrams were calculated on 160x160 μm images of the cone mosaic
acquired with an AO flood illumination retinal camera at 1.5 degrees eccentricity from the
fovea along all retinal meridians. From the cone spacing measures and Voronoi diagrams,
the linear dispersion index (LDi) and the heterogeneity packing index (HPi) were computed
respectively. Logistic regression analysis was conducted to discriminate DM1 patients without
diabetic retinopathy from controls using the cone metrics as predictors.
Results
Of the 16 DM1 patients, eight had no signs of diabetic retinopathy (noDR) and eight had
mild nonproliferative diabetic retinopathy (NPDR) on fundoscopy. On average, cone density,
LDi and HPi values were significantly different (P<0.05) between noDR or NPDR eyes
and controls, with these differences increasing with duration of diabetes. However, each
cone metric alone was not sufficiently sensitive to discriminate entirely between membership
of noDR cases and controls. The complementary use of all the three cone metrics in
the logistic regression model gained 100% accuracy to identify noDR cases with respect to
controls.
PLOS ONE | DOI:10.1371/journal.pone.0151380 March 10, 2016 1 / 14
OPEN ACCESS
Citation: Lombardo M, Parravano M, Serrao S,
Ziccardi L, Giannini D, Lombardo G (2016)
Investigation of Adaptive Optics Imaging Biomarkers
for Detecting Pathological Changes of the Cone
Mosaic in Patients with Type 1 Diabetes Mellitus.
PLoS ONE 11(3): e0151380. doi:10.1371/journal.
pone.0151380
Editor: Knut Stieger, Justus-Liebig-University
Giessen, GERMANY
Received: December 17, 2015
Accepted: February 27, 2016
Published: March 10, 2016
Copyright: © 2016 Lombardo et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited.
Data Availability Statement: All relevant data are
within the paper and its Supporting Information files.
Funding: Research for this work was supported by
the Italian Ministry of Health (5x1000 funding), by the
National Framework Program for Research and
Innovation PON (grant n. 01_00110) and by
Fondazione Roma. The funders had no role in study
design, data collection and analysis, decision to
publish, or preparation of the manuscript. Vision
Engineering Italy srl funder provided support in the
form of salaries for author GL, but did not have any
Conclusion
The present set of AO imaging biomarkers identified reliably abnormalities in the spatial
arrangement of the parafoveal cones in DM1 patients, even when no signs of diabetic retinopathy
were seen on fundoscopy
Relational Neural Machines
Deep learning has been shown to achieve impressive results in several tasks
where a large amount of training data is available. However, deep learning
solely focuses on the accuracy of the predictions, neglecting the reasoning
process leading to a decision, which is a major issue in life-critical
applications. Probabilistic logic reasoning allows to exploit both statistical
regularities and specific domain expertise to perform reasoning under
uncertainty, but its scalability and brittle integration with the layers
processing the sensory data have greatly limited its applications. For these
reasons, combining deep architectures and probabilistic logic reasoning is a
fundamental goal towards the development of intelligent agents operating in
complex environments. This paper presents Relational Neural Machines, a novel
framework allowing to jointly train the parameters of the learners and of a
First--Order Logic based reasoner. A Relational Neural Machine is able to
recover both classical learning from supervised data in case of pure
sub-symbolic learning, and Markov Logic Networks in case of pure symbolic
reasoning, while allowing to jointly train and perform inference in hybrid
learning tasks. Proper algorithmic solutions are devised to make learning and
inference tractable in large-scale problems. The experiments show promising
results in different relational tasks
T-Norms Driven Loss Functions for Machine Learning
Neural-symbolic approaches have recently gained popularity to inject prior
knowledge into a learner without requiring it to induce this knowledge from
data. These approaches can potentially learn competitive solutions with a
significant reduction of the amount of supervised data. A large class of
neural-symbolic approaches is based on First-Order Logic to represent prior
knowledge, relaxed to a differentiable form using fuzzy logic. This paper shows
that the loss function expressing these neural-symbolic learning tasks can be
unambiguously determined given the selection of a t-norm generator. When
restricted to supervised learning, the presented theoretical apparatus provides
a clean justification to the popular cross-entropy loss, which has been shown
to provide faster convergence and to reduce the vanishing gradient problem in
very deep structures. However, the proposed learning formulation extends the
advantages of the cross-entropy loss to the general knowledge that can be
represented by a neural-symbolic method. Therefore, the methodology allows the
development of a novel class of loss functions, which are shown in the
experimental results to lead to faster convergence rates than the approaches
previously proposed in the literature
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