Discrete instability in nonlinear lattices

The discrete multiscale analysis for boundary value problems in nonlinear discrete systems leads to a first order discrete modulational instability above a threshold amplitude for wave numbers beyond the zero of group velocity dispersion. Applied to the electrical lattice [Phys. Rev. E, 51 (1995) 6127 ], this acurately explains the experimental instability at wave numbers beyond 1.25 . The theory is also briefly discussed for sine-Gordon and Toda lattices.Comment: 1 figure, revtex, published: Phys. Rev. Lett. 83 (1999) 232

GANDALF: Generative Adversarial Networks with Discriminator-Adaptive Loss Fine-tuning for Alzheimer's Disease Diagnosis from MRI

Positron Emission Tomography (PET) is now regarded as the gold standard for the diagnosis of Alzheimer's Disease (AD). However, PET imaging can be prohibitive in terms of cost and planning, and is also among the imaging techniques with the highest dosage of radiation. Magnetic Resonance Imaging (MRI), in contrast, is more widely available and provides more flexibility when setting the desired image resolution. Unfortunately, the diagnosis of AD using MRI is difficult due to the very subtle physiological differences between healthy and AD subjects visible on MRI. As a result, many attempts have been made to synthesize PET images from MR images using generative adversarial networks (GANs) in the interest of enabling the diagnosis of AD from MR. Existing work on PET synthesis from MRI has largely focused on Conditional GANs, where MR images are used to generate PET images and subsequently used for AD diagnosis. There is no end-to-end training goal. This paper proposes an alternative approach to the aforementioned, where AD diagnosis is incorporated in the GAN training objective to achieve the best AD classification performance. Different GAN lossesare fine-tuned based on the discriminator performance, and the overall training is stabilized. The proposed network architecture and training regime show state-of-the-art performance for three- and four- class AD classification tasks.Comment: Accepted for publication at the MICCAI 2020 conferenc

Asymmetric gap soliton modes in diatomic lattices with cubic and quartic nonlinearity

Nonlinear localized excitations in one-dimensional diatomic lattices with cubic and quartic nonlinearity are considered analytically by a quasi-discreteness approach. The criteria for the occurence of asymmetric gap solitons (with vibrating frequency lying in the gap of phonon bands) and small-amplitude, asymmetric intrinsic localized modes (with the vibrating frequency being above all the phonon bands) are obtained explicitly based on the modulational instabilities of corresponding linear lattice plane waves. The expressions of particle displacement for all these nonlinear localized excitations are also given. The result is applied to standard two-body potentials of the Toda, Born-Mayer-Coulomb, Lennard-Jones, and Morse type. The comparison with previous numerical study of the anharmonic gap modes in diatomic lattices for the standard two-body potentials is made and good agreement is found.Comment: 24 pages in Revtex, 2 PS figure

Remote monitoring of patients with implantable cardioverter-defibrillators: Can results from large clinical trials be transposed to clinical practice?

SummaryBackgroundRemote monitoring (RM) is increasingly used to follow up patients with implantable cardioverter-defibrillators (ICDs). Randomized control trials provide evidence for the benefit of this intervention, but data for RM in daily clinical practice with multiple-brands and unselected patients is lacking.AimsTo assess the effect of RM on patient management and clinical outcome for recipients of ICDs in daily practice.MethodsWe reviewed ICD recipients followed up at our institution in 2009 with RM or with traditional hospital only (HO) follow-up. We looked at the effect of RM on the number of scheduled ambulatory follow-ups and urgent unscheduled consultations, the time between onset of asymptomatic events to clinical intervention and the clinical effectiveness of all consultations. We also evaluated the proportion of RM notifications representing clinically relevant situations.ResultsWe included 355 patients retrospectively (RM: n=144, HO: n=211, 76.9% male, 60.3±15.2years old, 50.1% with ICDs for primary prevention and mean left ventricular ejection fraction 35.5±14.5%). Average follow-up was 13.5months. The RM group required less scheduled ambulatory follow-up consultations (1.8 vs. 2.1/patient/year; P<0.0001) and a far lower median time between the onset of asymptomatic events and clinical intervention (7 vs. 76days; P=0.016). Of the 784 scheduled ambulatory follow-up consultations carried out, only 152 (19.4%) resulted in therapeutic intervention or ICD reprogramming. We also found that the vast majority of RM notifications (61.9%) were of no clinical relevance.ConclusionRM allows early management of asymptomatic events and a reduction in scheduled ambulatory follow-up consultations in daily clinical practice, without compromising safety, endorsing RM as the new standard of care for ICD recipients

Human-Centered Design Components in Spiral Model to Improve Mobility of Older Adults

As humans grow older, their cognitive needs change more frequently due to distal and proximal life events. Designers and developers need to come up with better designs that integrate older users’ needs in a short period of time with more interaction with the users. Therefore, the positioning of human end users in the center of the design itself is not the key to the success of design artifacts while designing applications for older adults to use a smartphone as a promising tool for journey planner while using public transportation. This study analyzed the use of human-centered design (HCD) components, the spiral model, and the design for failure (DfF) approach to improve the interactions between older users and designers/developers in gathering usability needs in the concept stage and during the development of the app with short iterative cycles. To illustrate the importance of the applied approach, a case study with particular focus on older adults is presented.The results presented in this study are based on “Assistant” project funded by AAL JP, co-funded by the European Union. The authors would like to thank Dr. Stefan Carmien, my colleague in Assistant, for mentoring and for reading and making comments in the earlier versions of this chapter; participating research institutes; funding agencies; and companies from Finland, Spain, Austria, France, and the United Kingdom for their active support throughout the project

Investigating reliable amyloid accumulation in Centiloids: Results from the AMYPAD Prognostic and Natural History Study.

To support clinical trial designs focused on early interventions, our study determined reliable early amyloid-β (Aβ) accumulation based on Centiloids (CL) in pre-dementia populations. A total of 1032 participants from the Amyloid Imaging to Prevent Alzheimer's Disease-Prognostic and Natural History Study (AMYPAD-PNHS) and Insight46 who underwent [ F]flutemetamol, [ F]florbetaben or [ F]florbetapir amyloid-PET were included. A normative strategy was used to define reliable accumulation by estimating the 95 percentile of longitudinal measurements in sub-populations (N  = 101/750, N  = 35/382) expected to remain stable over time. The baseline CL threshold that optimally predicts future accumulation was investigated using precision-recall analyses. Accumulation rates were examined using linear mixed-effect models. Reliable accumulation in the PNHS was estimated to occur at >3.0 CL/year. Baseline CL of 16 [12,19] best predicted future Aβ-accumulators. Rates of amyloid accumulation were tracer-independent, lower for APOE ε4 non-carriers, and for subjects with higher levels of education. Our results support a 12-20 CL window for inclusion into early secondary prevention studies. Reliable accumulation definition warrants further investigations. [Abstract copyright: © 2024 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.

Neuropsychiatric profiles and conversion to dementia in mild cognitive impairment, a latent class analysis

Altres ajuts: Fondo Europeo de Desarrollo Regional (FEDER)Altres ajuts: Generalitat de Catalunya. Programa CERCAAltres ajuts: Instituto de Salud Carlos III (CIBERSAM i CIBERNED)Altres ajuts: Fundació "La Caixa"Altres ajuts: Grífols SA (GR@ACE project)Neuropsychiatric symptoms (NPS) have been recently addressed as risk factors of conversion to Alzheimer's disease (AD) and other dementia types in patients diagnosed with Mild Cognitive Impairment (MCI). Our aim was to determine profiles based on the prominent NPS in MCI patients and to explore the predictive value of these profiles on conversion to specific types of dementia. A total of 2137 MCI patients monitored in a memory clinic were included in the study. Four NPS profiles emerged (classes), which were defined by preeminent symptoms: Irritability, Apathy, Anxiety/Depression and Asymptomatic. Irritability and Apathy were predictors of conversion to dementia (HR = 1.43 and 1.56, respectively). Anxiety/depression class showed no risk effect of conversion when compared to Asymptomatic class. Irritability class appeared as the most discriminant neuropsychiatric condition to identify non-AD converters (i.e., frontotemporal dementia, vascular dementia, Parkinson's disease and dementia with Lewy Bodies). The findings revealed that consistent subgroups of MCI patients could be identified among comorbid basal NPS. The preeminent NPS showed to behave differentially on conversion to dementia, beyond AD. Therefore, NPS should be used as early diagnosis facilitators, and should also guide clinicians to detect patients with different illness trajectories in the progression of MCI