3,994 research outputs found
The Impact of Isolation Kernel on Agglomerative Hierarchical Clustering Algorithms
Agglomerative hierarchical clustering (AHC) is one of the popular clustering
approaches. Existing AHC methods, which are based on a distance measure, have
one key issue: it has difficulty in identifying adjacent clusters with varied
densities, regardless of the cluster extraction methods applied on the
resultant dendrogram. In this paper, we identify the root cause of this issue
and show that the use of a data-dependent kernel (instead of distance or
existing kernel) provides an effective means to address it. We analyse the
condition under which existing AHC methods fail to extract clusters
effectively; and the reason why the data-dependent kernel is an effective
remedy. This leads to a new approach to kernerlise existing hierarchical
clustering algorithms such as existing traditional AHC algorithms, HDBSCAN, GDL
and PHA. In each of these algorithms, our empirical evaluation shows that a
recently introduced Isolation Kernel produces a higher quality or purer
dendrogram than distance, Gaussian Kernel and adaptive Gaussian Kernel
Few-Shot Learning with a Strong Teacher
Few-shot learning (FSL) aims to train a strong classifier using limited
labeled examples. Many existing works take the meta-learning approach, sampling
few-shot tasks in turn and optimizing the few-shot learner's performance on
classifying the query examples. In this paper, we point out two potential
weaknesses of this approach. First, the sampled query examples may not provide
sufficient supervision for the few-shot learner. Second, the effectiveness of
meta-learning diminishes sharply with increasing shots (i.e., the number of
training examples per class). To resolve these issues, we propose a novel
objective to directly train the few-shot learner to perform like a strong
classifier. Concretely, we associate each sampled few-shot task with a strong
classifier, which is learned with ample labeled examples. The strong classifier
has a better generalization ability and we use it to supervise the few-shot
learner. We present an efficient way to construct the strong classifier, making
our proposed objective an easily plug-and-play term to existing meta-learning
based FSL methods. We validate our approach in combinations with many
representative meta-learning methods. On several benchmark datasets including
miniImageNet and tiredImageNet, our approach leads to a notable improvement
across a variety of tasks. More importantly, with our approach, meta-learning
based FSL methods can consistently outperform non-meta-learning based ones,
even in a many-shot setting, greatly strengthening their applicability
Recommended from our members
Temozolomide and Pazopanib Combined with FOLFOX Regressed a Primary Colorectal Cancer in a Patient-derived Orthotopic Xenograft Mouse Model.
PurposeThe goal of the present study was to determine the efficacy of temozolomide (TEM) and pazopanib (PAZ) combined with FOLFOX (oxaliplatin, leucovorin and 5-fluorouracil) on a colorectal cancer patient-derived orthotopic xenograft (PDOX) mouse model.Materials and methodsA colorectal cancer tumor from a patient previously established in non-transgenic nude mice was implanted subcutaneously in transgenic green fluorescence protein (GFP)-expressing nude mice in order to label the tumor stromal cells with GFP. Then labeled tumors were orthotopically implanted into the cecum of nude mice. Mice were randomized into four groups: Group 1, untreated control; group 2, TEM + PAZ; group 3, FOLFOX; group 4, TEM + PAZ plus FOLFOX. Tumor width, length, and mouse body weight were measured weekly. The Fluor Vivo imaging System was used to image the GFP-lableled tumor stromal cells in vivo. H&E staining and immunohistochemical staining were used for histological analysis.ResultsAll three treatments inhibited tumor growth as compared to the untreated control group. The combination of TEM + PAZ + FOLFOX regressed tumor growth significantly more effectively than TEM + PAZ or FOLFOX. Only the combination of TEM + PAZ + FOLFOX group caused a decrease in body weight. PAZ suppressed lymph vessels density in the colorectal cancer PDOX mouse model suggesting inhibition of lymphangiogenesis.ConclusionOur results suggest that the combination of TEM + PAZ + FOLFOX has clinical potential for colorectal cancer patient
Study on Characteristic of Overburden Movement in Unsymmetrical Isolated Longwall Mining Using Microseismic Technique
AbstractBased on the key stratum theory, overlying strata structures above a typical unsymmetrical isolated working face (LW10302) was analyzed, and a microseismic monitoring was also applied to characterize the fracturing propagations associated with overburden movement in mining progress. The results show that the overlying strata above LW10302 can be divided into key strata of different grades, and the formed “O-X” fracturing structure have the main and inferior “O-X” ones. The spatial evolution of seismic events demonstrated that seismic activities fits very well with the overburden fracturing patterns and stress manifestation around the longwall face. In the mining process, most of the events located within the surrounding strata of LW10301 and 10302 while low energy events distributed mainly in multiple roof and floor strata, and the strong tremors occurred almost within the super-thick primary key strata and appeared to be related to shear fracturing of large-scale overburden movement. Additionally, seismic signals corresponding to different failure mechanisms show different characteristics in waveform features. The study in this paper indicates that microseismic monitoring can provide invaluable information to characterize the mining-induced seismicity and reveal the failure patterns within strata associated with mining, which will greatly benefit the alleviation and prevention of rock burst hazards in mine
Streaming CTR Prediction: Rethinking Recommendation Task for Real-World Streaming Data
The Click-Through Rate (CTR) prediction task is critical in industrial
recommender systems, where models are usually deployed on dynamic streaming
data in practical applications. Such streaming data in real-world recommender
systems face many challenges, such as distribution shift, temporal
non-stationarity, and systematic biases, which bring difficulties to the
training and utilizing of recommendation models. However, most existing studies
approach the CTR prediction as a classification task on static datasets,
assuming that the train and test sets are independent and identically
distributed (a.k.a, i.i.d. assumption). To bridge this gap, we formulate the
CTR prediction problem in streaming scenarios as a Streaming CTR Prediction
task. Accordingly, we propose dedicated benchmark settings and metrics to
evaluate and analyze the performance of the models in streaming data. To better
understand the differences compared to traditional CTR prediction tasks, we
delve into the factors that may affect the model performance, such as parameter
scale, normalization, regularization, etc. The results reveal the existence of
the ''streaming learning dilemma'', whereby the same factor may have different
effects on model performance in the static and streaming scenarios. Based on
the findings, we propose two simple but inspiring methods (i.e., tuning key
parameters and exemplar replay) that significantly improve the effectiveness of
the CTR models in the new streaming scenario. We hope our work will inspire
further research on streaming CTR prediction and help improve the robustness
and adaptability of recommender systems
The Nematic Energy Scale and the Missing Electron Pocket in FeSe
Superconductivity emerges in proximity to a nematic phase in most iron-based
superconductors. It is therefore important to understand the impact of
nematicity on the electronic structure. Orbital assignment and tracking across
the nematic phase transition prove to be challenging due to the multiband
nature of iron-based superconductors and twinning effects. Here, we report a
detailed study of the electronic structure of fully detwinned FeSe across the
nematic phase transition using angle-resolved photoemission spectroscopy. We
clearly observe a nematicity-driven band reconstruction involving dxz, dyz, and
dxy orbitals. The nematic energy scale between dxz and dyz bands reaches a
maximum of 50 meV at the Brillouin zone corner. We are also able to track the
dxz electron pocket across the nematic transition and explain its absence in
the nematic state. Our comprehensive data of the electronic structure provide
an accurate basis for theoretical models of the superconducting pairing in
FeSe
- …