465 research outputs found
Towards -finiteness: -deformed open string amplitude
Revisiting the Coon amplitude, a deformation of the Veneziano amplitude with
a logarithmic generalization of linear Regge trajectories, we scrutinize its
potential origins in a worldsheet theory by proposing a definition of its
-deformation through the integral representation of the -beta function.
By utilizing -deformed commutation relations and vertex operators, we derive
the Coon amplitude within the framework of the dual resonance model. We extend
this to the open-string context by -deforming the Lie algebra
, resulting in a well-defined -deformed open superstring
amplitude. We further demonstrate that the -prefactor in the Coon amplitude
arises naturally from the property of the -integral. Furthermore, we find
that two different types of -prefactors, corresponding to different
representations of the same scattering amplitude, are essentially the same by
leveraging the properties of -numbers. Our findings indicate that the
-deformed string amplitude defines a continuous family of amplitudes,
illustrating how string amplitudes with a finite uniquely flow
to the amplitudes of scalar scattering in field theory at energy scale
as changes from to . This happens without the requirement
of an expansion, presenting a fresh perspective on the
connection between string and field theories
Learning Rich Geographical Representations: Predicting Colorectal Cancer Survival in the State of Iowa
Neural networks are capable of learning rich, nonlinear feature
representations shown to be beneficial in many predictive tasks. In this work,
we use these models to explore the use of geographical features in predicting
colorectal cancer survival curves for patients in the state of Iowa, spanning
the years 1989 to 2012. Specifically, we compare model performance using a
newly defined metric -- area between the curves (ABC) -- to assess (a) whether
survival curves can be reasonably predicted for colorectal cancer patients in
the state of Iowa, (b) whether geographical features improve predictive
performance, and (c) whether a simple binary representation or richer, spectral
clustering-based representation perform better. Our findings suggest that
survival curves can be reasonably estimated on average, with predictive
performance deviating at the five-year survival mark. We also find that
geographical features improve predictive performance, and that the best
performance is obtained using richer, spectral analysis-elicited features.Comment: 8 page
Utilizzo della tecnologia blockchain applicata alle licenze software
Negli ultimi anni la blockchain ha attratto molto interesse da varie aziende e ricercatori, studiando i miglioramenti che una tecnologia come questa potrebbe avere in vari settori, da quello finanziario a quello medico o immobiliare. Abbiamo scelto una delle possibili aree di applicazione, la gestione delle licenze software, e ne abbiamo sviluppato un sistema basato sulla blockchain di Ethereum. La tesi inizierà con un’introduzione al concetto di blockchain, fornendo le conoscenze necessarie per comprendere questa tecnologia; in seguito, illustrerà il processo che ha portato alla costruzione di questo sistema e infine analizzerà i possibili vantaggi e svantaggi che la blockchain può offrire in un ambito come le licenze software
Code Integrity Attestation for PLCs using Black Box Neural Network Predictions
Cyber-physical systems (CPSs) are widespread in critical domains, and
significant damage can be caused if an attacker is able to modify the code of
their programmable logic controllers (PLCs). Unfortunately, traditional
techniques for attesting code integrity (i.e. verifying that it has not been
modified) rely on firmware access or roots-of-trust, neither of which
proprietary or legacy PLCs are likely to provide. In this paper, we propose a
practical code integrity checking solution based on privacy-preserving black
box models that instead attest the input/output behaviour of PLC programs.
Using faithful offline copies of the PLC programs, we identify their most
important inputs through an information flow analysis, execute them on multiple
combinations to collect data, then train neural networks able to predict PLC
outputs (i.e. actuator commands) from their inputs. By exploiting the black box
nature of the model, our solution maintains the privacy of the original PLC
code and does not assume that attackers are unaware of its presence. The trust
instead comes from the fact that it is extremely hard to attack the PLC code
and neural networks at the same time and with consistent outcomes. We evaluated
our approach on a modern six-stage water treatment plant testbed, finding that
it could predict actuator states from PLC inputs with near-100% accuracy, and
thus could detect all 120 effective code mutations that we subjected the PLCs
to. Finally, we found that it is not practically possible to simultaneously
modify the PLC code and apply discreet adversarial noise to our attesters in a
way that leads to consistent (mis-)predictions.Comment: Accepted by the 29th ACM Joint European Software Engineering
Conference and Symposium on the Foundations of Software Engineering (ESEC/FSE
2021
Learning from mutants: Using code mutation to learn and monitor invariants of a cyber-physical system
Cyber-physical systems (CPS) consist of sensors, actuators, and controllers
all communicating over a network; if any subset becomes compromised, an
attacker could cause significant damage. With access to data logs and a model
of the CPS, the physical effects of an attack could potentially be detected
before any damage is done. Manually building a model that is accurate enough in
practice, however, is extremely difficult. In this paper, we propose a novel
approach for constructing models of CPS automatically, by applying supervised
machine learning to data traces obtained after systematically seeding their
software components with faults ("mutants"). We demonstrate the efficacy of
this approach on the simulator of a real-world water purification plant,
presenting a framework that automatically generates mutants, collects data
traces, and learns an SVM-based model. Using cross-validation and statistical
model checking, we show that the learnt model characterises an invariant
physical property of the system. Furthermore, we demonstrate the usefulness of
the invariant by subjecting the system to 55 network and code-modification
attacks, and showing that it can detect 85% of them from the data logs
generated at runtime.Comment: Accepted by IEEE S&P 201
Sequential Keystroke Behavioral Biometrics for Mobile User Identification via Multi-view Deep Learning
With the rapid growth in smartphone usage, more organizations begin to focus
on providing better services for mobile users. User identification can help
these organizations to identify their customers and then cater services that
have been customized for them. Currently, the use of cookies is the most common
form to identify users. However, cookies are not easily transportable (e.g.,
when a user uses a different login account, cookies do not follow the user).
This limitation motivates the need to use behavior biometric for user
identification. In this paper, we propose DEEPSERVICE, a new technique that can
identify mobile users based on user's keystroke information captured by a
special keyboard or web browser. Our evaluation results indicate that
DEEPSERVICE is highly accurate in identifying mobile users (over 93% accuracy).
The technique is also efficient and only takes less than 1 ms to perform
identification.Comment: 2017 Joint European Conference on Machine Learning and Knowledge
Discovery in Database
Impaired Spinal Glucocorticoid Receptor Signaling Contributes to the Attenuating Effect of Depression on Mechanical Allodynia and Thermal Hyperalgesia in Rats with Neuropathic Pain
Although depression-induced altered pain perception has been described in several laboratory and clinical studies, its neurobiological mechanism in the central nervous system (CNS), particularly in the spinal dorsal horn, remains unclear. Therefore, in this study, we aimed to clarify whether nociceptive sensitivity of neuropathic pain is altered in the olfactory bulbectomy (OB) model of depression and whether glucocorticoid receptor (GR), which is involved in the etio-pathologic mechanisms of both major depression and neuropathic pain, contributes to these processes in the spinal dorsal horn of male Sprague-Dawley rats. The results showed that mechanical allodynia and thermal hyperalgesia induced by spinal nerve ligation (SNL) were attenuated in OB-SNL rats with decreased spinal GR expression and nuclear translocation, whereas non-olfactory bulbectomy (NOB)-SNL rats showed increased spinal GR nuclear translocation. In addition, decreased GR nuclear translocation with normal mechanical nociception and hypoalgesia of thermal nociception were observed in OB-Sham rats. Intrathecal injection (i.t.) of GR agonist dexamethasone (Dex; 4 ÎĽg/rat/day for 1 week) eliminated the attenuating effect of depression on nociceptive hypersensitivity in OB-SNL rats and aggravated neuropathic pain in NOB-SNL rats, which was associated with the up-regulation of brain-derived neurotrophic factor (BDNF), TrkB and NR2B expression in the spinal dorsal horn. The present study shows that depression attenuates the mechanical allodynia and thermal hyperalgesia of neuropathic pain and suggests that altered spinal GR-BDNF-TrkB signaling may be one of the reasons for depression-induced hypoalgesia
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