Adaptive Anchor Label Propagation for Transductive Few-Shot Learning

Few-shot learning addresses the issue of classifying images using limited labeled data. Exploiting unlabeled data through the use of transductive inference methods such as label propagation has been shown to improve the performance of few-shot learning significantly. Label propagation infers pseudo-labels for unlabeled data by utilizing a constructed graph that exploits the underlying manifold structure of the data. However, a limitation of the existing label propagation approaches is that the positions of all data points are fixed and might be sub-optimal so that the algorithm is not as effective as possible. In this work, we propose a novel algorithm that adapts the feature embeddings of the labeled data by minimizing a differentiable loss function optimizing their positions in the manifold in the process. Our novel algorithm, Adaptive Anchor Label Propagation}, outperforms the standard label propagation algorithm by as much as 7% and 2% in the 1-shot and 5-shot settings respectively. We provide experimental results highlighting the merits of our algorithm on four widely used few-shot benchmark datasets, namely miniImageNet, tieredImageNet, CUB and CIFAR-FS and two commonly used backbones, ResNet12 and WideResNet-28-10. The source code can be found at https://github.com/MichalisLazarou/A2LP.Comment: published in ICIP 202

Formation of Toxic Unsaturated Multifunctional and Organosulfur Compounds From the Photosensitized Processing of Fluorene and DMSO at the Air-Water Interface

Polycyclic aromatic hydrocarbons and dimethyl sulfoxide (DMSO) are ubiquitous at the sea surface. Photochemistry at the air-sea interface is a potentially important source of volatile organic compounds, but the relevant chemical processes are currently not well known. When aqueous solutions containing a mixture of fluorene (FL) and DMSO are irradiated with actinic radiation, a large suite of unsaturated high molecular weight compounds appear in the aqueous phase; a broad variety of saturated and unsaturated oxygenated multifunctional compounds are also observed in the gas phase, most of which are more toxic than FL. A possible sequence of steps leading to some of the observed compounds in aqueous solution as well as in the gas phase is proposed. The reaction pathways initiated by excited triplet state of FL (3FL*) are supported by theoretical calculations of the reaction Gibbs energies. The formation of organosulfur compounds has been observed to occur in the gas and the aqueous phases initiated by the reaction between 3FL* and DMSO. The aforementioned photosensitized chemistry at the water surface can have an important impact on the formation of secondary organic aerosol in marine boundary layer as polycyclic aromatic hydrocarbons and DMSO enriched at the water surface are ubiquitous. ©2020. American Geophysical Union. All Rights Reserved

Sarcopenic Obesity in Individuals With Neurodisabilities: The SarcObeNDS Study.

IntroductionPatients with neurodisabilities (NDS) are prone to alterations in body composition. Sarcopenic obesity (SO) is a condition characterized by increased adipose tissue accompanied by sarcopenia. The aim of this study was to investigate the prevalence of SO in patients with NDS, including stroke, spinal cord, and traumatic brain injuries.MethodsThe study Sarcopenic Obesity in NeuroDisabled Subjects (acronym: SarcObeNDS) was a cross-sectional study of hospitalized patients (n = 82) and healthy controls (n = 32) with a mean age of 60.00 ± 14.22 years old. SO and sarcopenia were assessed through total body fat % (TBF %), fat mass index (fat mass to height2: FMI = FM/h2; kg/m2), and skeletal muscle index (appendicular skeletal muscle to height2: SMI = ASM/h2; kg/m2) via full-body dual-energy X-ray absorptiometry (DXA). This study was registered in the international database ClinicalTrials.gov with the unique identification number NCT03863379.ResultsA statistically significant difference was found in SMI (7.18 ± 0.95 vs. 6.00 ± 1.13 kg/m2, p p = 0.783) and FMI (p = 0.143) between groups. The results remained the same after controlling the results for gender and BMI. A strong positive correlation was demonstrated between BMI and TBF for the total population (r = 0.616, p r = 0.616, p r = 0.728, p ConclusionIn summary, we observed significantly lower BMI and SMI scores in both genders compared to healthy controls. At the clinical level, a timely diagnosis and rapid treatment of sarcopenia and/or obesity in this population may prevent further metabolic repercussions accompanied by higher functional decline and lower quality of life

STUDY OF PHOTOCHEMISTRY AND CHEMICAL KINETICS OF SIMPLE NITRAMINES

THIS THESIS DESCRIDES THE DISSOCIATION OF THE SIMPLE NITRAMINES, DIMETHYLNITRAMINE AND DIETHYLNITRAMINE THROUGH THE IRRADIATION WITH A PULSE CARDON DIOXIDELASER. IRRADIATION LEADS TO THE SCISSION OF THE WEAKEST BOND BETWEEN NITROGEN ATOMS IN THE MOLECULE. THE REACTIONS THAT FOLLOW ARE MAINLY OXIDATION REACTIONS OF THE DIALKYLAMINYL RADICAL PRODUCED PRIMARILY. THE CHEMICAL REACTIVITY OF THE METHYL HYDROGENS OF DIMETHYLNITRAMINE WAS STUDIED WITH THE "VERY-LOW-PRESSURE-REACTOR" TECHNIQUE BY EVALUATING THE MECHANISM AND THE KINETIC PARAMETERS OF THE REACTION OF DIMETHYLNITRAMINE AND CHLORINE ATOMS. FINALLY, THE SYNTHESIS OF MOLECULES ENCOUNTERED IN THIS THESIS AND APPLICATION PROGRAMS ARE PRESENTED.ΣΤΗΝ ΠΑΡΟΥΣΑ ΔΙΑΤΡΙΒΗ ΠΕΡΙΓΡΑΦΕΤΑΙ Η ΔΙΑΣΠΑΣΗ ΤΩΝ ΔΥΟ ΑΠΛΩΝ ΝΙΤΡΑΜΙΝΩΝ, ΔΙΜΕΘΥΛΟΝΙΤΡΑΜΙΝΗ ΚΑΙ ΔΙΑΙΘΥΛΟΝΙΤΡΑΜΙΝΗ ΔΙΑ ΤΗΣ ΑΚΤΙΝΟΒΟΛΗΣΗΣ ΜΕ ΕΝΑ ΠΑΛΜΙΚΟ ΛΕΙΖΕΡ ΔΙΟΞΕΙΔΙΟΥ ΤΟΥ ΑΝΘΡΑΚΑ. Η ΑΚΤΙΝΟΒΟΛΗΣΗ ΟΔΗΓΕΙ ΣΕ ΘΡΑΥΣΗ ΤΟΥ ΑΣΘΕΝΕΣΤΕΡΟΥ ΔΕΣΜΟΥ ΑΝΑΜΕΣΑ ΣΤΑ ΔΥΟ ΑΤΟΜΑ ΑΖΩΤΟΥ ΤΟΥ ΜΟΡΙΟΥ. ΟΙ ΑΝΤΙΔΡΑΣΕΙΣ ΠΟΥ ΑΚΟΛΟΥΘΟΥΝ ΧΑΡΑΚΤΗΡΙΖΟΝΤΑΙ ΒΑΣΙΚΑ ΑΠΟ ΑΝΤΙΔΡΑΣΕΙΣ ΟΞΕΙΔΩΣΗΣ ΤΗΣ ΠΑΡΑΓΟΜΕΝΗΣ ΔΙΑΛΚΥΛΑΜΙΝΟΡΙΖΑΣΑΠΟ ΤΟ ΠΑΤΡΙΚΟ ΜΟΡΙΟ ΚΑΙ ΤΑ ΜΟΡΙΑ ΔΙΟΞΕΙΔΙΟΥ ΤΟΥ ΑΖΩΤΟΥ ΠΟΥ ΠΑΡΑΓΟΝΤΑΙ ΠΡΩΤΟΓΕΝΩΣ. Η ΧΗΜΙΚΗ ΔΡΑΣΤΙΚΟΤΗΤΑ ΤΩΝ ΜΕΘΥΛΙΚΩΝ ΥΔΡΟΓΟΝΩΝ ΤΗΣ ΔΙΜΕΘΥΛΟΝΙΤΡΑΜΙΝΗΣ ΜΕΛΕΤΗΘΗΚΕ ΣΤΟ ΣΥΣΤΗΜΑ "ΠΟΛΥ -ΧΑΜΗΛΗΣ-ΠΙΕΣΗΣ-ΑΝΤΙΔΡΑΣΤΗΡΑΣ", ΥΠΟΛΟΓΙΖΟΝΤΑΣ ΤΟΝ ΜΗΧΑΝΙΣΜΟ ΚΑΙ ΤΙΣ ΚΙΝΗΤΙΚΕΣ ΠΑΡΑΜΕΤΡΟΥΣ ΤΗΣ ΑΝΤΙΔΡΑΣΗΣ ΔΙΜΕΘΥΛΟΝΙΤΡΑΜΙΝΗΣ ΚΑΙ ΑΤΟΜΙΚΟΥ ΧΛΩΡΙΟΥ. ΣΥΝΘΕΤΙΚΕΣ ΜΕΘΟΔΟΙ ΚΑΙ ΓΡΑΦΗ ΠΡΟΓΡΑΜΜΑΤΩΝ ΑΝΑΠΤΥΣΣΟΝΤΑΙ ΣΤΟΤΕΛΟΣ

Iterative label cleaning for transductive and semi-supervised few-shot learning

Few-shot learning amounts to learning representations and acquiring knowledge such that novel tasks may be solved with both supervision and data being limited. Improved performance is possible by transductive inference, where the entire test set is available concurrently, and semi-supervised learning, where more unlabeled data is available. These problems are closely related because there is little or no adaptation of the representation in novel tasks. Focusing on these two settings, we introduce a new algorithm that leverages the manifold structure of the labeled and unlabeled data distribution to predict pseudo-labels, while balancing over classes and using the loss value distribution of a limited-capacity classifier to select the cleanest labels, iterately improving the quality of pseudo-labels. Our solution sets new state of the art on four benchmark datasets, namely \emph{mini}ImageNet, \emph{tiered}ImageNet, CUB and CIFAR-FS, while being robust over feature space pre-processing and the quantity of available data

Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability

β-Cyclodextrin (β-CD) dimers have been prepared using the bioorthogonal Staudinger ligation for the first time. In addition to a known linker, methyl 2-(diphenylphosphanyl)terephthalate, a doubly active linker was specifically developed that enabled connection of two β-CD units in a single step and in aqueous/organic media, under mild conditions and with good yields. A three-carbon spacer between the β-CD torus and the azido group was required for facile dimer formation. The products, as studied by NMR spectroscopy, were found to adopt closed conformations by intramolecular self-inclusion. On the other hand, association via intermolecular binding was also observed in aqueous solution, confirmed by DOSY NMR experiments. Despite self-inclusion, the β-CD cavities were capable of guest encapsulation, as shown by titration experiments: the binding constant with 1-adamantylamine was similar to that of natural β-CD. Theoretical calculations for isolated molecules (PM3 level of theory) and in the presence of solvent [water, PM3(COSMO)] as well as DFT calculations suggested that the compounds prefer to adopt conformations which bring the phenyl groups either inside the β-CD cavity (inclusion) or over its narrow side (vicinal). Thus, Staudinger ligation could be the method of choice for linking CDs exhibiting (i) ease of preparation in aqueous media, in short steps, under mild conditions and in good yields, (ii) satisfactory aqueous solubility and independent binding capacity of the cavities

Geochemical modeling of mercury in coastal groundwater

The systematic analysis of groundwater in the Greek island of Skiathos revealed a seasonal increase of total mercury concentrations after the extensive groundwater abstraction during the busy and heavily touristic summer months. This contamination was accompanied by a corresponding increase of the chloride content of groundwater, attributed to seawater intrusion into the freshwater-depleted aquifer within mercury-rich bedrock. The effects of elevated concentrations of chloride anions in the mobilization of mercury and its speciation were addressed by geochemical equilibrium modeling, considering cinnabar (HgS) as the mineral source of mercury. Adsorption onto hydrous ferric oxide (Fe2O3·H2O) was a necessary ingredient of the geochemical model for bringing the calculated concentrations in agreement with field measurements, after optimization of the cinnabar/adsorbent mass ratio to a value of 4.9 × 10−8. The speciation of mercury was found to depend on the acidity and redox status as well as on the chloride content of groundwater. Mercury concentrations in the groundwater of Skiathos rise above the World Health Organization limit of 1 μg L−1 for a seawater intrusion higher than 3 %, with HgCl2 being the dominant species followed by HgClOH, HgCl3− and HgCl42−. The assumed concentration of dissolved organic matter in groundwater had a negligible impact on the mercury speciation and its mobilization by chloride