Exploring Weight Balancing on Long-Tailed Recognition Problem

Recognition problems in long-tailed data, where the sample size per class is heavily skewed, have recently gained importance because the distribution of the sample size per class in a dataset is generally exponential unless the sample size is intentionally adjusted. Various approaches have been devised to address these problems. Recently, weight balancing, which combines well-known classical regularization techniques with two-stage training, has been proposed. Despite its simplicity, it is known for its high performance against existing methods devised in various ways. However, there is a lack of understanding as to why this approach is effective for long-tailed data. In this study, we analyze the method focusing on neural collapse and cone effect at each training stage and find that it can be decomposed into the increase in Fisher's discriminant ratio of the feature extractor caused by weight decay and cross entropy loss and implicit logit adjustment caused by weight decay and class-balanced loss. Our analysis shows that the training method can be further simplified by reducing the number of training stages to one while increasing accuracy

Narrative review of current COPD status in Japan

Chronic obstructive pulmonary disease (COPD) causes morbidity and mortality worldwide. Due to the improvement in environmental sanitation and medical care, the general life span has increased in the past decades in Japan. However, many older patients with COPD develop a wide range of comorbidities, and the impairments in the activities of daily living result in frailty and increase social and economic burdens. Population-based studies have shown that the prevalence of COPD is approximately 10% among subjects aged ≥40 years, but more than 80% of COPD patients are underdiagnosed. The Ministry of Health, Labour, and Welfare in Japan proposed the National Health Promotion in the 21st century, termed Health Japan 21 (the second term), in 2013 to prevent the onset and progression of noncommunicable diseases (NCDs), including COPD. The government, medical society, and community have been attempting to increase the recognition of COPD and promote smoking cessation. Additionally, Japanese cohorts have revealed distinct clinical features in Japanese patients with COPD, including lower rates of patient-reported exacerbations, less frequent coexisting cardiovascular disease and metabolic syndrome, and lower use of inhaled corticosteroids in Japan compared to the Western countries. Moreover, the poor adherence to inhaled medications is found in approximately 20% of subjects, and rehabilitation is performed in 26% of hospitalized patients with COPD. Therefore, more efforts should be made to improve adherence and access to pulmonary rehabilitation. Overall, Japanese COPD patients share common clinical and social features with COPD patients in other countries. Further international corroboration may help establish better comprehensive management of the disease

Domain switching dynamics in relaxor ferroelectric Pb(Mg₁⁄₃Nb₂⁄₃)O₃-PbTiO₃ revealed by time-resolved high-voltage electron microscopy

Ferroelectric domain dynamics in Pb(Mg₁⁄₃Nb₂⁄₃)O₃-PbTiO₃ single crystals have been studied by in situ biasing high-voltage transmission electron microscopy with a direct electron detection camera. We have achieved time-resolved recording of polarization switching in real space on a 2.5 ms time scale. The reversible response of micrometer-scale domains was observed by applying an electric field of 1 kV/mm. Detailed analyses on smaller sized domains 100-500 nm in size revealed that the domain switching initiated at a corner of a rectangular domain and propagated inward rapidly. The switching proceeded within 60 ms and the maximum switching rate, as fast as 6-8 μm/s, was observed. The domain switching kinetics was classified as two-dimensional nucleation and growth mode based on the Kolmogolov-Avrami-Ishibashi model.Kazuhisa Sato and Naoya Asakura, "Domain switching dynamics in relaxor ferroelectric Pb(Mg₁⁄₃Nb₂⁄₃)O₃-PbTiO₃ revealed by time-resolved high-voltage electron microscopy", Journal of Applied Physics 130, 164101 (2021) https://doi.org/10.1063/5.0064291

Associations of CT evaluations of antigravity muscles, emphysema and airway disease with longitudinal outcomes in patients with COPD

Multiple CT indices are associated with disease progression and mortality in patients with COPD, but which indices have the strongest association remain unestablished. This longitudinal 10-year observational study (n=247) showed that the emphysema severity on CT is more closely associated with the progression of airflow limitation and that a reduction in the cross-sectional area of erector spinae muscles (ESMCSA) on CT is more closely associated with mortality than the other CT indices, independent of patient demographics and pulmonary function. ESMCSA is a useful CT index that is more closely associated with long-term mortality than emphysema and airway disease in patients with COPD

Structural Modeling of HIV-1 Env-gp120

Variable V1/V2 and V3 loops on human immunodeficiency virus type 1 (HIV-1) envelope-gp120 core play key roles in modulating viral competence to recognize two infection receptors, CD4 and chemokine-receptors. However, molecular bases for the modulation largely remain unclear. To address these issues, we constructed structural models for a full-length gp120 in CD4-free and -bound states. The models showed topologies of gp120 surface loop that agree with those in reported structural data. Molecular dynamics simulation showed that in the unliganded state, V1/V2 loop settled into a thermodynamically stable arrangement near V3 loop for conformational masking of V3 tip, a potent neutralization epitope. In the CD4-bound state, however, V1/V2 loop was rearranged near the bound CD4 to support CD4 binding. In parallel, cell-based adaptation in the absence of anti-viral antibody pressures led to the identification of amino acid substitutions that individually enhance viral entry and growth efficiencies in association with reduced sensitivity to CCR5 antagonist TAK-779. Notably, all these substitutions were positioned on the receptors binding surfaces in V1/V2 or V3 loop. In silico structural studies predicted some physical changes of gp120 by substitutions with alterations in viral replication phenotypes. These data suggest that V1/V2 loop is critical for creating a gp120 structure that masks co-receptor binding site compatible with maintenance of viral infectivity, and for tuning a functional balance of gp120 between immune escape ability and infectivity to optimize HIV-1 replication fitness

In silico Analysis of HIV-1 Env-gp120 Reveals Structural Bases for Viral Adaptation in Growth-Restrictive Cells

Variable V1/V2 and V3 loops on human immunodeficiency virus type 1 (HIV-1) envelope-gp120 core play key roles in modulating viral competence to recognize two infection receptors, CD4 and chemokine-receptors. However, molecular bases for the modulation largely remain unclear. To address these issues, we constructed structural models for a full-length gp120 in CD4-free and -bound states. The models showed topologies of gp120 surface loop that agree with those in reported structural data. Molecular dynamics simulation showed that in the unliganded state, V1/V2 loop settled into a thermodynamically stable arrangement near V3 loop for conformational masking of V3 tip, a potent neutralization epitope. In the CD4-bound state, however, V1/V2 loop was rearranged near the bound CD4 to support CD4 binding. In parallel, cell-based adaptation in the absence of anti-viral antibody pressures led to the identification of amino acid substitutions that individually enhance viral entry and growth efficiencies in association with reduced sensitivity to CCR5 antagonist TAK-779. Notably, all these substitutions were positioned on the receptors binding surfaces in V1/V2 or V3 loop. In silico structural studies predicted some physical changes of gp120 by substitutions with alterations in viral replication phenotypes. These data suggest that V1/V2 loop is critical for creating a gp120 structure that masks co-receptor binding site compatible with maintenance of viral infectivity, and for tuning a functional balance of gp120 between immune escape ability and infectivity to optimize HIV-1 replication fitness