4,446 research outputs found
Online Class Incremental Learning on Stochastic Blurry Task Boundary via Mask and Visual Prompt Tuning
Continual learning aims to learn a model from a continuous stream of data,
but it mainly assumes a fixed number of data and tasks with clear task
boundaries. However, in real-world scenarios, the number of input data and
tasks is constantly changing in a statistical way, not a static way. Although
recently introduced incremental learning scenarios having blurry task
boundaries somewhat address the above issues, they still do not fully reflect
the statistical properties of real-world situations because of the fixed ratio
of disjoint and blurry samples. In this paper, we propose a new Stochastic
incremental Blurry task boundary scenario, called Si-Blurry, which reflects the
stochastic properties of the real-world. We find that there are two major
challenges in the Si-Blurry scenario: (1) inter- and intra-task forgettings and
(2) class imbalance problem. To alleviate them, we introduce Mask and Visual
Prompt tuning (MVP). In MVP, to address the inter- and intra-task forgetting
issues, we propose a novel instance-wise logit masking and contrastive visual
prompt tuning loss. Both of them help our model discern the classes to be
learned in the current batch. It results in consolidating the previous
knowledge. In addition, to alleviate the class imbalance problem, we introduce
a new gradient similarity-based focal loss and adaptive feature scaling to ease
overfitting to the major classes and underfitting to the minor classes.
Extensive experiments show that our proposed MVP significantly outperforms the
existing state-of-the-art methods in our challenging Si-Blurry scenario
3,3′-Dimethyl-1,1′-[2,2′-bipyridine-5,5′-diylbis(methylene)]diimidazol-3-ium bis(hexafluorophosphate)
The title compound, C20H22N6
2+·2PF6
−, was prepared by the reaction of 5,5′-bis(bromomethyl)-2,2′-bipyridine with 1-methylimidazole. The main molecule lies on an inversion center located at the mid-point of the C—C bond joining the two pyridine rings. The asymmetric unit therefore contains one half-molecule and one hexafluorophosphate anion. The dihedral angle between the pyridine and imidazole rings is 76.93 (7)°. In the crystal, weak intermolecular C—H⋯F hydrogen bonds contribute to the stabilization of the packing
Bis[μ-N-(pyridin-2-ylmethyl)pyridin-2-amine-κ2 N:N′]disilver(I) bis(trifluoromethanesulfonate)
In the binuclear title compound, [Ag2(C11H11N3)2](CF3O3S)2, the complex cation is centrosymmetric, with the unique Ag+ cation coordinated by two pyridine N atoms from two symmetry-related N-(pyridin-2-ylmethyl)pyridin-2-amine ligands in a geometry slightly distorted from linear [N—Ag—N 161.02 (7)°]. This set-up leads to the formation of a 14-membered cyclic dimer. The two pyridine rings coordinated to the Ag+ cation are tilted by 80.19 (7)° with respect to each other. Intermolecular N—H⋯O hydrogen-bonding interactions between the cyclic dimer and the anion exist. A two-dimensional network parallel to the ac plane is constructed by three weak Ag⋯(O,N) interactions as well as an F⋯F contact of 2.890 (4) Å
Methyl 9-diethylamino-2,2-bis(4-methoxyphenyl)-2H-benzo[h]chromene-5-carboxylate
In the title compound, C31H29NO5, the methyl carboxylate and dimethylamino groups on the naphthopyran group are almost coplanar with the naphthopyran ring system [r.m.s. deviations = 0.08 (2) and 0.161 (2) Å, respectively]. The dihedral angle between the methyl carboxylate and dimethylamino groups is 4.9 (1)°. The pyran ring has an envelope conformation with the quaternary C atom out of plane by 0.4739 (13) Å. The methoxyphenyl substituent forms a dihedral angle of 16.6 (1)° with the plane of the benzene ring, while the other methoxyphenyl group is almost coplanar, making a dihedral angle of 1.4 (1)°
1,4-Bis(4-pyridylsulfanylmethyl)benzene
In the title compound, C18H16N2S2, a crystallographic inversion centre lies at the centre of the benzene ring, and the two terminal 4-mercaptopyridyl groups adopt an anti geometry. Each benzene ring makes a dihedral angle of 55.4 (1)° with the plane of the benzene fragment. The crystal structure is stabilized by C—H⋯π interactions between a benzene H atom and a pyridyl ring of a neighbouring molecule. In addition, the crystal structure exhibits intermolecular C—H⋯N interactions
Improvisation of classification performance based on feature optimization for differentiation of Parkinson’s disease from other neurological diseases using gait characteristics
Most neurological disorders that include Parkinson’s disease (PD) as well as other neurological diseases such as Amyotrophic Lateral Sclerosis (ALS) and Huntington’s disease (HD) have some common abnormalities regarding the movement, vocal, and cognitive behaviors of sufferers. Variations in the manifestation of these types of abnormality help distinguish one disorder from another. In this study, differentiation was performed based on the gait characteristics of patients afflicted by different neurological disorders. In the recent past, many researchers have applied different machine learning and feature selection techniques to the classification of different groups of patients based on common abnormalities. However, in an era of modernization where the focus is on timely low-cost automatization and pattern recognition, such techniques require improvisation to provide high performance. We attempted to improve the performance of such techniques using different feature optimization methods, such as a genetic algorithm (GA) and principal component analysis (PCA), and applying different classification approaches, i.e., linear, nonlinear, and probabilistic classifiers. In this study, gait dynamics data of patients suffering with PD, ALS, and HD were collated from a public database, and a binary classification approach was used by taking PD as one group and adopting ALS+HD as another group. Performance comparison was achieved using different classification techniques that incorporated optimized feature sets obtained from GA and PCA. In comparison with other classifiers using different feature sets, the highest accuracy (97.87%) was obtained using random forest combined with GA-based feature sets. The results provide evidence that could assist medical practitioners in differentiating PD from other neurological diseases using gait characteristics
N,N-Diethyl-4-[9-methoxy-6-(4-methoxyphenyl)-5-methyl-2-phenyl-2H-benzo[h]chromen-2-yl]aniline
In the title compound, C38H37NO3, the pyran ring has an envelope conformation with the quaternary Cq atom as the flap atom. The dihedral angle formed between the methoxyphenyl group and the naphthalene ring system is 67.32 (6)°. The ethylamino groups lie to the same side of the plane through the phenyl ring and form dihedral angles of 84.6 (3) and 75.8 (2)° with it
Corrigendum to “Local Relationship between Global-Flash Multifocal Electroretinogram Optic Nerve Head Components and Visual Field Defects in Patients with Glaucoma”
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