593 research outputs found
Uniqueness for a Stochastic Inviscid Dyadic Model
For the deterministic dyadic model of turbulence, there are examples of
initial conditions in which have more than one solution. The aim of this
paper is to prove that uniqueness, for all -initial conditions, is
restored when a suitable multiplicative noise is introduced. The noise is
formally energy preserving. Uniqueness is understood in the weak probabilistic
sense.Comment: 13 pages, no figures. Submitted to the Proceedings of the American
Mathematical Societ
Anomalous dissipation in a stochastic inviscid dyadic model
A stochastic version of an inviscid dyadic model of turbulence, with
multiplicative noise, is proved to exhibit energy dissipation in spite of the
formal energy conservation. As a consequence, global regular solutions cannot
exist. After some reductions, the main tool is the escape bahavior at infinity
of a certain birth and death process.Comment: Published in at http://dx.doi.org/10.1214/11-AAP768 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Anomalous dissipation in a stochastic inviscid dyadic model
A stochastic version of an inviscid dyadic model of turbulence, with
multiplicative noise, is proved to exhibit energy dissipation in spite of the
formal energy conservation. As a consequence, global regular solutions cannot
exist. After some reductions, the main tool is the escape bahavior at infinity
of a certain birth and death process.Comment: Published in at http://dx.doi.org/10.1214/11-AAP768 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
A dyadic model on a tree
We study an infinite system of non-linear differential equations coupled in a
tree-like structure. This system was previously introduced in the literature
and it is the model from which the dyadic shell model of turbulence was
derived. It mimics 3d Euler and Navier-Stokes equations in a rough
approximation of a wavelet decomposition. We prove existence of finite energy
solutions, anomalous dissipation in the inviscid unforced case, existence and
uniqueness of stationary solutions (either conservative or not) in the forced
case
Smooth solutions for the dyadic model
We consider the dyadic model, which is a toy model to test issues of
well-posedness and blow-up for the Navier-Stokes and Euler equations. We prove
well-posedness of positive solutions of the viscous problem in the relevant
scaling range which corresponds to Navier-Stokes. Likewise we prove
well-posedness for the inviscid problem (in a suitable regularity class) when
the parameter corresponds to the strongest transport effect of the
non-linearity
Positive and non-positive solutions for an inviscid dyadic model. Well-posedness and regularity
We improve regolarity and uniqueness results from the literature for the
inviscid dyadic model. We show that positive dyadic is globally well-posed for
every rate of growth of the scaling coefficients k_n = 2^{bn}. Some
regularity results are proved for positive solutions, namely \sup_n n^{-a}
k_n^{1/3} X_n(t) < \infty for a.e. t and \sup_n k_n^{1/3-1/(3b)} X_n(t) \leq C
t^{-1/3}t$. Moreover it is shown that under very general hypothesis,
solutions become positive after a finite time
Reproducibility and speed of landmarking process in cephalometric analysis using two input devices: mouse-driven cursor versus pen
To define if the new portable appliances, like smartphone, iPad, small laptop and tablet can be used in cephalometric tracing without dropping out the validity of any measurement.
METHODS:We investigated and compared the reproducibility and the speed of landmarks identification process on lateral X-rays in two input devices: a mouse-driven cursor and a pen used as input means in mobile devices. One expert located 22 landmarks on 15 lateral X-rays in a repeated measure design two times, at time T1 and T2, after at least one month. The Intraclass Correlation coefficient was used to evaluate the reproducibility for each landmark tracing and the agreement between the value derived from both input devices. Also, the mean errors in measurements, the standard deviation and the Friedman Test significans (P < 0.05) between both input were statistically evaluated.
RESULTS:All landmarks had a high agreement and the Friedman Test indicated statistically significant differences (P<0.05) for the identification of Na, Po, Pt, PNS, Ba, Pg, Gn, UIE, UIA, APOcc and PPOcc landmarks.
CONCLUSIONS:Even if the mouse input give higher agreement for landmark tracing the differences are really minimal and they can be ignored in private practice. We suggest the adequacy of pen input in clinical setting
DepthFormer: Multimodal Positional Encodings and Cross-Input Attention for Transformer-Based Segmentation Networks
Most approaches for semantic segmentation use only information from color
cameras to parse the scenes, yet recent advancements show that using depth data
allows to further improve performances. In this work, we focus on
transformer-based deep learning architectures, that have achieved
state-of-the-art performances on the segmentation task, and we propose to
employ depth information by embedding it in the positional encoding.
Effectively, we extend the network to multimodal data without adding any
parameters and in a natural way that makes use of the strength of transformers'
self-attention modules. We also investigate the idea of performing
cross-modality operations inside the attention module, swapping the key inputs
between the depth and color branches. Our approach consistently improves
performances on the Cityscapes benchmark
Oral hygiene management in patients with visual sensory disabilities
Aim: Oral hygiene maintenance is one of the most difficult tasks for visually impaired people. The aim of study was to investigate
about knowledge on oral hygiene practices among patients with visual sensory disabilities by proposing an effective management in order to
achieve and maintain oral health status of these patients. Methods:It was administered a questionnaire about oral health management
to the patients with visual disabilities accessing to dental unit of “Mons. Di Liegro” Hospital of Gaeta.
Results: The survey covered a sample of 49 patients, aged between 14 and 95 years. More than half (66%) was blind ( 65% of cases
with primary blindness and the remain ing 35% with secondary blindness). Only 32.65% brushed their teeth 3 times a day; 68% of the surveyed
patients limited home oral hygiene procedures to toothbrush and toothpaste; 79% used manual toothbrush; 49% of respondents report
ed odontophobia (it was basically generated by pain) often due to bad experience during childhood. More than half declared a dental office attendance as needed.
Conclusions: This study showed as, although starting from a compromised oral health and inadequate knowledge of oral hygiene
practices, visual impaired/ blind patients were able to achieve and maintain a good level of oral hygiene, using the most appropriate techniques and instrument
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