Cosmic Constraint to DGP Brane Model: Geometrical and Dynamical Perspectives

In this paper, the Dvali-Gabadadze-Porrati (DGP) brane model is confronted by current cosmic observational data sets from geometrical and dynamical perspectives. On the geometrical side, the recent released Union2 $557$ of type Ia supernovae (SN Ia), the baryon acoustic oscillation (BAO) from Sloan Digital Sky Survey and the Two Degree Galaxy Redshift Survey (transverse and radial to line-of-sight data points), the cosmic microwave background (CMB) measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations (shift parameters $R$, $l_a(z_\ast)$ and redshift at the last scatter surface $z_\ast$), ages of high redshifts galaxies, i.e. the lookback time (LT) and the high redshift Gamma Ray Bursts (GRBs) are used. On the dynamical side, data points about the growth function (GF) of matter linear perturbations are used. Using the same data sets combination, we also constrain the flat $\Lambda$CDM model as a comparison. The results show that current geometrical and dynamical observational data sets much favor flat $\Lambda$CDM model and the departure from it is above $4\sigma$($6\sigma$) for spatially flat DGP model with(without) SN systematic errors. The consistence of growth function data points is checked in terms of relative departure of redshift-distance relation.Comment: 14 pages, 5 figures, 2 tables, accepted for publication in Physical Review

The Integrated Sachs-Wolfe Effect in Time Varying Vacuum Model

The integrated Sachs-Wolfe (ISW) effect is an important implication for dark energy. In this paper, we have calculated the power spectrum of the ISW effect in the time varying vacuum cosmological model, where the model parameter $\beta=4.407$ is obtained by the observational constraint of the growth rate. It's found that the source of the ISW effect is not only affected by the different evolutions of the Hubble function $H(a)$ and the dimensionless matter density $\Omega_m(a)$, but also by the different growth function $D_+(a)$, all of which are changed due to the presence of matter production term in the time varying vacuum model. However, the difference of the ISW effect in $\Lambda(t)\textmd{CDM}$ model and $\Lambda \textmd{CDM}$ model is lessened to a certain extent due to the integration from the time of last scattering to the present. It's implied that the observations of the galaxies with high redshift are required to distinguish the two models

DropIT: Dropping Intermediate Tensors for Memory-Efficient DNN Training

A standard hardware bottleneck when training deep neural networks is GPU memory. The bulk of memory is occupied by caching intermediate tensors for gradient computation in the backward pass. We propose a novel method to reduce this footprint - Dropping Intermediate Tensors (DropIT). DropIT drops min-k elements of the intermediate tensors and approximates gradients from the sparsified tensors in the backward pass. Theoretically, DropIT reduces noise on estimated gradients and therefore has a higher rate of convergence than vanilla-SGD. Experiments show that we can drop up to 90% of the intermediate tensor elements in fully-connected and convolutional layers while achieving higher testing accuracy for Visual Transformers and Convolutional Neural Networks on various tasks (e.g. classification, object detection).Our code and models are available at https://github.com/chenjoya/dropitComment: 16 pages. DropIT can save memory & improve accuracy, providing a new perspective of dropping in activation compressed training than quantizatio

PFOS induces adipogenesis and glucose uptake in association with activation of Nrf2 signaling pathway

PFOS is a chemical of nearly ubiquitous exposure in humans. Recent studies have associated PFOS exposure to adipose tissue-related effects. The present study was to determine whether PFOS alters the process of adipogenesis and regulates insulin-stimulated glucose uptake in mouse and human preadipocytes. In murine-derived 3T3-L1 preadipocytes, PFOS enhanced hormone-induced differentiation to adipocytes and adipogenic gene expression, increased insulin-stimulated glucose uptake at concentrations ranging from 10 to 100 μM, and enhanced Glucose transporter type 4 and Insulin receptor substrate-1 expression. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), NAD(P)H dehydrogenase, quinone 1 and Glutamate-cysteine ligase, catalytic subunit were significantly induced in 3T3-L1 cells treated with PFOS, along with a robust induction of Antioxidant Response Element (ARE) reporter in mouse embryonic fibroblasts isolated from ARE-hPAP transgenic mice by PFOS treatment. Chromatin immunoprecipitation assays further illustrated that PFOS increased Nrf2 binding to ARE sites in mouse Nqo1 promoter, suggesting that PFOS activated Nrf2 signaling in murine-derived preadipocytes. Additionally, PFOS administration in mice (100 μg/kg/day) induced adipogenic gene expression and activated Nrf2 signaling in epididymal white adipose tissue. Moreover, the treatment on human visceral preadipocytes illustrated that PFOS (5 and 50 μM) promoted adipogenesis and increased cellular lipid accumulation. It was observed that PFOS increased Nrf2 binding to ARE sites in association with Nrf2 signaling activation, induction of Peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α expression, and increased adipogenesis. This study points to a potential role of PFOS in dysregulation of adipose tissue expandability, and warrants further investigations on the adverse effects of persistent pollutants on human health