5,545 research outputs found
Optical Monitoring of the Seyfert Galaxy NGC 4151 and Possible Periodicities in the Historical Light Curve
We report B, V, and R band CCD photometry of the Seyfert galaxy NGC 4151
obtained with the 1.0-m telescope at Weihai Observatory of Shandong University
and the 1.56-m telescope at Shanghai Astronomical Observatory from 2005
December to 2013 February. Combining all available data from literature, we
have constructed a historical light curve from 1910 to 2013 to study the
periodicity of the source using three different methods (the Jurkevich method,
the Lomb-Scargle periodogram method and the Discrete Correlation Function
method). We find possible periods of P_1=4\pm0.1, P_2=7.5\pm0.3 and
P_3=15.9\pm0.3 yr.Comment: 8 pages, 5 figures, Accepted by Research in Astronomy and
Astrophysic
Polyamine Function in Plants: Metabolism, Regulation on Development, and Roles in Abiotic Stress Responses
Polyamines (PAs) are low molecular weight aliphatic nitrogenous bases containing two or more amino groups. They are produced by organisms during metabolism and are present in almost all cells. Because they play important roles in diverse plant growth and developmental processes and in environmental stress responses, they are considered as a new kind of plant biostimulant. With the development of molecular biotechnology techniques, there is increasing evidence that PAs, whether applied exogenously or produced endogenously via genetic engineering, can positively affect plant growth, productivity, and stress tolerance. However, it is still not fully understood how PAs regulate plant growth and stress responses. In this review, we attempt to cover these information gaps and provide a comprehensive and critical assessment of the published literature on the relationships between PAs and plant flowering, embryo development, senescence, and responses to several (mainly abiotic) stresses. The aim of this review is to summarize how PAs improve plants' productivity, and to provide a basis for future research on the mechanism of action of PAs in plant growth and development. Future perspectives for PA research are also suggested
Catch-Up Distillation: You Only Need to Train Once for Accelerating Sampling
Diffusion Probability Models (DPMs) have made impressive advancements in
various machine learning domains. However, achieving high-quality synthetic
samples typically involves performing a large number of sampling steps, which
impedes the possibility of real-time sample synthesis. Traditional accelerated
sampling algorithms via knowledge distillation rely on pre-trained model
weights and discrete time step scenarios, necessitating additional training
sessions to achieve their goals. To address these issues, we propose the
Catch-Up Distillation (CUD), which encourages the current moment output of the
velocity estimation model ``catch up'' with its previous moment output.
Specifically, CUD adjusts the original Ordinary Differential Equation (ODE)
training objective to align the current moment output with both the ground
truth label and the previous moment output, utilizing Runge-Kutta-based
multi-step alignment distillation for precise ODE estimation while preventing
asynchronous updates. Furthermore, we investigate the design space for CUDs
under continuous time-step scenarios and analyze how to determine the suitable
strategies. To demonstrate CUD's effectiveness, we conduct thorough ablation
and comparison experiments on CIFAR-10, MNIST, and ImageNet-64. On CIFAR-10, we
obtain a FID of 2.80 by sampling in 15 steps under one-session training and the
new state-of-the-art FID of 3.37 by sampling in one step with additional
training. This latter result necessitated only 620k iterations with a batch
size of 128, in contrast to Consistency Distillation, which demanded 2100k
iterations with a larger batch size of 256. Our code is released at
https://anonymous.4open.science/r/Catch-Up-Distillation-E31F
Tracking the Yadong-Gulu Rift belt with multiple thermochronometers on modern detritus from Yarlung-Tsangpo River
Abstract HKT-ISTP 2013
A
Dimension Increase via Hierarchical Hydrogen Bonding from Simple Pincer-like Mononuclear complexes
A tetradentate symmetric ligand bearing both coordination and hydrogen bonding sites, N1,N3-bis(1-(1H-benzimidazol-2-yl)-ethylidene)propane-1,3-diamine (H2bbepd) was utilized to synthesize a series of transition metal complexes, namely [Co(H2bbepd)(H2O)2]·2ClO4
(1), [Cu(H2bbepd)(OTs-)]·OTs- (2),[Cu(bbepd)(CH3OH)] (3), [Cd(H2bbepd)(NO3)2]·CH3OH (4), [Cd(H2bbepd)(CH3OH)Cl]·Cl (5), and
[Cd(bbepd)(CH3OH)2] (6). These complexes show similar discrete pincer-like coordination units, possessing different arrangements of hydrogen bonding donor and acceptor sites. With or without the aid of uncoordinated anions and solvent molecules, such mononuclear
units have been effectively involved in the construction of hierarchical hydrogen bonding assemblies (successively via level I and level II), leading to discrete binuclear ring (complex 2), one-dimensional chain or ribbon (complexes 3, 4 and 6) and
two-dimensional layer (complexes 1 and 5) aggregates
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