494 research outputs found
A Euclidean Distance Matrix Model for Convex Clustering
Clustering has been one of the most basic and essential problems in
unsupervised learning due to various applications in many critical fields. The
recently proposed sum-of-nums (SON) model by Pelckmans et al. (2005), Lindsten
et al. (2011) and Hocking et al. (2011) has received a lot of attention. The
advantage of the SON model is the theoretical guarantee in terms of perfect
recovery, established by Sun et al. (2018). It also provides great
opportunities for designing efficient algorithms for solving the SON model. The
semismooth Newton based augmented Lagrangian method by Sun et al. (2018) has
demonstrated its superior performance over the alternating direction method of
multipliers (ADMM) and the alternating minimization algorithm (AMA). In this
paper, we propose a Euclidean distance matrix model based on the SON model. An
efficient majorization penalty algorithm is proposed to solve the resulting
model. Extensive numerical experiments are conducted to demonstrate the
efficiency of the proposed model and the majorization penalty algorithm.Comment: 32 pages, 3 figures, 3 table
Tumor elimination by clustered microRNAs miR-306 and miR-79 via noncanonical activation of JNK signaling
JNK signaling plays a critical role in both tumor promotion and tumor suppression. Here, we identified clustered microRNAs (miRNAs) miR-306 and miR-79 as novel tumor-suppressor miRNAs that specifically eliminate JNK-activated tumors in Drosophila. While showing only a slight effect on normal tissue growth, miR-306 and miR-79 strongly suppressed growth of multiple tumor models, including malignant tumors caused by Ras activation and cell polarity defects. Mechanistically, these miRNAs commonly target the mRNA of an E3 ubiquitin ligase ring finger protein 146 (RNF146). We found that RNF146 promotes degradation of tankyrase (Tnks), an ADP-ribose polymerase that promotes JNK activation in a noncanonical manner. Thus, downregulation of RNF146 by miR-306 and miR-79 leads to hyper-enhancement of JNK activation. Our data show that, while JNK activity is essential for tumor growth, elevation of miR-306 or miR-79 overactivate JNK signaling to the lethal level via noncanonical JNK pathway and thus eliminate tumors, providing a new miRNA-based strategy against cancer
Bis[μ-2-(2-carboxylatophenyl)acetato]-κ3 O 1,O 1′:O 2;κ3 O 2:O 1,O 1′-bis[aqua(1,10-phenanthroline-κ2 N,N′)nickel(II)]
The title compound, [Ni2(C9H6O4)2(C12H8N2)2(H2O)2], is isostructural with the ZnII analogue. Each NiII atom is coordinated in a distorted octahedral geometry by three O atoms from two homophthalate anions, one aqua O atom and two 1,10-phenanthroline N atoms. The two NiII atoms are linked by two bridging homophthalate dianions into a centrosymmetric dinuclear unit. The dinuclear units are linked into one-dimensional ladder-like chains along [100] by O—H⋯O hydrogen bonds between the coordinated water molecules and one of the O atoms of the carboxylatomethyl group
Evaluating Fairness Without Sensitive Attributes: A Framework Using Only Auxiliary Models
Although the volume of literature and public attention on machine learning
fairness has been growing significantly, in practice some tasks as basic as
measuring fairness, which is the first step in studying and promoting fairness,
can be challenging. This is because sensitive attributes are often unavailable
due to privacy regulations. The straightforward solution is to use auxiliary
models to predict the missing sensitive attributes. However, our theoretical
analyses show that the estimation error of the directly measured fairness
metrics is proportional to the error rates of auxiliary models' predictions.
Existing works that attempt to reduce the estimation error often require strong
assumptions, e.g. access to the ground-truth sensitive attributes or some form
of conditional independence. In this paper, we drop those assumptions and
propose a framework that uses only off-the-shelf auxiliary models. The main
challenge is how to reduce the negative impact of imperfectly predicted
sensitive attributes on the fairness metrics without knowing the ground-truth
sensitive attributes. Inspired by the noisy label learning literature, we first
derive a closed-form relationship between the directly measured fairness
metrics and their corresponding ground-truth metrics. And then we estimate some
key statistics (most importantly transition matrix in the noisy label
literature), which we use, together with the derived relationship, to calibrate
the fairness metrics. In addition, we theoretically prove the upper bound of
the estimation error in our calibrated metrics and show our method can
substantially decrease the estimation error especially when auxiliary models
are inaccurate or the target model is highly biased. Experiments on COMPAS and
CelebA validate our theoretical analyses and show our method can measure
fairness significantly more accurately than baselines under favorable
circumstances
Hesperetin protects SH-SY5Y cells against 6- hydroxydopamine-induced neurotoxicity via activation of NRF2/ARE signaling pathways
Purpose: To investigation the protective effects of hesperetin against 6-hydroxydopamine (6-OHDA)- induced neurotoxicity.
Methods: SH-SY5Y cells were incubated with 6-OHDA to create an in vitro model of neurotoxicity. This model was used to test the neuroprotective effects of hesperetin. Cell viability was assessed by MTT and lactate dehydrogenase (LDH) release assays. Flow cytometry and western blot were used to quantify apoptosis. Oxidative stress was evaluated by determining intracellular glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), and reactive oxygen species (ROS).
Results: In SH-SY5Y cells, treatment with 6-OHDA decreased cell viability and promoted LDH release. However, exogenous hesperetin protected against 6-OHDA-mediated toxicity. Similarly, although incubation with 6-OHDA induced apoptosis and increased cleaved caspase-3 and -9 levels, treatment with hesperetin protected against these effects. Treatment with 6-OHDA also led to significant oxidative stress, as indicated by reduced GSH and SOD levels and increased MDA and ROS levels in SH-SY5Y cells. However, these changes were reversed by pre-treatment with hesperetin. Of interest, hesperetin led to changes in 6-OHDA-induced expression of NRF2, heme oxygenase-1 (HO-1), glutamate-cysteine ligase (GCL) catalytic subunit (GCLC), and GCL modulatory (GCLM).
Conclusion: Hesperetin protects against cell toxicity, apoptosis, and oxidative stress via activation of NRF2 pathway in a 6-OHDA-induced model of neurotoxicity. Future studies should investigate the use of hesperetin as a potential therapeutic approach for prevention or management of Parkinson’s disease.
Keywords: Hesperetin, 6-OHDA, Neurotoxicity, NRF2, Parkinson’s diseas
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