542 research outputs found
Memory-Efficient Topic Modeling
As one of the simplest probabilistic topic modeling techniques, latent
Dirichlet allocation (LDA) has found many important applications in text
mining, computer vision and computational biology. Recent training algorithms
for LDA can be interpreted within a unified message passing framework. However,
message passing requires storing previous messages with a large amount of
memory space, increasing linearly with the number of documents or the number of
topics. Therefore, the high memory usage is often a major problem for topic
modeling of massive corpora containing a large number of topics. To reduce the
space complexity, we propose a novel algorithm without storing previous
messages for training LDA: tiny belief propagation (TBP). The basic idea of TBP
relates the message passing algorithms with the non-negative matrix
factorization (NMF) algorithms, which absorb the message updating into the
message passing process, and thus avoid storing previous messages. Experimental
results on four large data sets confirm that TBP performs comparably well or
even better than current state-of-the-art training algorithms for LDA but with
a much less memory consumption. TBP can do topic modeling when massive corpora
cannot fit in the computer memory, for example, extracting thematic topics from
7 GB PUBMED corpora on a common desktop computer with 2GB memory.Comment: 20 pages, 7 figure
A New Approach to Speeding Up Topic Modeling
Latent Dirichlet allocation (LDA) is a widely-used probabilistic topic
modeling paradigm, and recently finds many applications in computer vision and
computational biology. In this paper, we propose a fast and accurate batch
algorithm, active belief propagation (ABP), for training LDA. Usually batch LDA
algorithms require repeated scanning of the entire corpus and searching the
complete topic space. To process massive corpora having a large number of
topics, the training iteration of batch LDA algorithms is often inefficient and
time-consuming. To accelerate the training speed, ABP actively scans the subset
of corpus and searches the subset of topic space for topic modeling, therefore
saves enormous training time in each iteration. To ensure accuracy, ABP selects
only those documents and topics that contribute to the largest residuals within
the residual belief propagation (RBP) framework. On four real-world corpora,
ABP performs around to times faster than state-of-the-art batch LDA
algorithms with a comparable topic modeling accuracy.Comment: 14 pages, 12 figure
Novel SPP Water Management Strategy and Its Applications
Clean freshwater is the most precious resource in the world and the development of water resources has had a very long history, as early as humans changed from being hunters and food collectors to modern civilization. At very early stage, people had to rely on creeks, rivers and lakes for their water demand that was relatively small, and today humans have accumulated the knowledge and techniques for water storage, building artificial lakes or reservoirs to meet their huge water demand due to industrialization and urbanization. The Wworld’s earliest large dam was the Sadd-el-kafara Dam built in Egypt between 2950 and 2690 B.C. Up to now, water from lakes and reservoirs is still the main source for people’s water supply. However these large water bodies suffer two problems incurred by nature and human being, one is sedimentation and the other water pollution. Two of them jointly reduce the available amount of clean water and deteriorate the water quality. Consequently, approximate 1.1 billion people lack of safe drinking water and between 2 and 5 million people die annually from water-related disease (Gleick, 2004). It is understandable that with the population growth in the world, it is difficult to provide sufficient clean water to meet the demand; on the other hand, our natural systems are under pressure from drought (too little), floods (too much), pollution (too dirty), climate change, and other stresses. This creates serious challenges for water management
Tramadol Pretreatment Enhances Ketamine-Induced Antidepressant Effects and Increases Mammalian Target of Rapamycin in Rat Hippocampus and Prefrontal Cortex
Several lines of evidence have demonstrated that acute administration of ketamine elicits fast-acting antidepressant effects. Moreover, tramadol also has potential antidepressant effects. The aim of this study was to investigate the effects of pretreatment with tramadol on ketamine-induced antidepressant activity and was to determine the expression of mammalian target of rapamycin (mTOR) in rat hippocampus and prefrontal cortex. Rats were intraperitoneally administrated with ketamine at the dose of 10 mg/kg or saline 1 h before the second episode of the forced swimming test (FST). Tramadol or saline was intraperitoneally pretreated 30 min before the former administration of ketamine or saline. The locomotor activity and the immobility time of FST were both measured. After that, rats were sacrificed to determine the expression of mTOR in hippocampus and prefrontal cortex. Tramadol at the dose of 5 mg/kg administrated alone did not elicit the antidepressant effects. More importantly, pretreatment with tramadol enhanced the ketamine-induced antidepressant effects and upregulated the expression of mTOR in rat hippocampus and prefrontal cortex. Pretreatment with tramadol enhances the ketamine-induced antidepressant effects, which is associated with the increased expression of mTOR in rat hippocampus and prefrontal cortex
Insecticidal Activity of the Leaf and Stem Water Extract of Gelsemium elegans against Solenopsis invicta
A comprehensive green worker ants control method that can be used to replace traditional chemical synthetic insecticides. In this study, the leaves and stems of Gelsemium elegans were extracted with water as the solvent, and the bioactivity of G. elegans against worker ants was determined by the “water tube” method. The bioassay results of insecticidal activity showed that when the time was extended to the 10th day, the mortality of worker ants treated with G. elegans extract reached 55.00% (1/20 leaf extract), 46.67% (1/20 stem extract) and 45.00% (1 mg/kg koumine). And the behavioral impact test results showed that the aggregation rate was reduced to 56.67% (1/100 leaf extract), 60.00% (1/100 stem extract) and 60.00% (0.5 mg/kg koumine); the climbing rate was reduced to 60.00 % (1/100 leaf extract), 58.33% (1/100 stem extract) and 58.33% (0.5 mg/kg koumine). The effect on the walking ability of worker ants is obvious. The walking rate drops to 1.53cm/s (1/100 leaf extract), 1.60cm/s (1/100 stem extract) and 1.47cm/s (0.5 mg/kg koumine). Therefore, we conclude that the water extract of G. elegans can be used for long-term continuous control of worker ants, which can be used to replace traditional chemical synthetic insecticides
The Fumigating Activity of Litsea cubeba oil and Citral on Solenopsis invicta
This paper studied the fumigating activity of Litsea cubeba oil and citral on Solenopsis invicta, identified and analyzed the chemical constituents and volatile components of L. cubeba oil via solid-phase microextraction which were then identified via gas chromatography-mass spectrometry. The results showed that citral and (z)-3,7-dimethylocta-2,6-diena were the main components of L. cubeba oil, as well as its volatile compounds. According to the experimental results, L. cubeba oil and citral had good fumigating activity on workers, and also had significant inhibition on the walking ability and climbing ability of workers. At the same time, the effects of the two agentia on the fumigating activity and behavioral inhibition of microergate were stronger than those of macroergate. After treating with L. cubeba oil and citral for 24 hours, the walking rate and grasping rate of microergate were both 0 %. The results showed that L. cubeba oil and citral had good control effect on S. invicta
Energy dependence of production in pp collisions with the PACIAE model
In this work we investigate the production in proton-proton
collisions at the center-of-mass energy () equal to 2.76, 5.02, 7, 8
and 13 TeV with a parton and hadron cascade model PACIAE 2.2a. It is based on
PYTHIA but extended considering the partonic and hadronic rescatterings before
and after hadronization, respectively. In the PYTHIA sector the
production quantum chromodynamics processes are selected specially and a bias
factor is proposed correspondingly. The calculated total cross sections, the
differential cross sections as a function of the transverse momentum and the
rapidity of in the forward rapidity region reproduce the corresponding
experimental measurements reasonably well. In the mid-rapidity region, the
double differential cross sections at 5.02, 7 and 13 TeV are also
in a good agreement with the experimental data. Moreover, we predict the double
differential cross section as well as the total cross section of at
8 TeV, which could be validated when the experimental data is
available.Comment: 6 pages, 8 figures, 3 table
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