The Application of Continuous Wavelet Transform Based Foreground Subtraction Method in 21 cm Sky Surveys

We propose a continuous wavelet transform based non-parametric foreground subtraction method for the detection of redshifted 21 cm signal from the epoch of reionization. This method works based on the assumption that the foreground spectra are smooth in frequency domain, while the 21 cm signal spectrum is full of saw-tooth-like structures, thus their characteristic scales are significantly different. We can distinguish them in the wavelet coefficient space easily and perform the foreground subtraction. Compared with the traditional spectral fitting based method, our method is more tolerant to complex foregrounds. Furthermore, we also find that when the instrument has uncorrected response error, our method can also work significantly better than the spectral fitting based method. Our method can obtain similar results with the Wp smoothing method, which is also a non-parametric method, but our method consumes much less computing time.Comment: Accepted by Ap

Predicting Aesthetic Score Distribution through Cumulative Jensen-Shannon Divergence

Aesthetic quality prediction is a challenging task in the computer vision community because of the complex interplay with semantic contents and photographic technologies. Recent studies on the powerful deep learning based aesthetic quality assessment usually use a binary high-low label or a numerical score to represent the aesthetic quality. However the scalar representation cannot describe well the underlying varieties of the human perception of aesthetics. In this work, we propose to predict the aesthetic score distribution (i.e., a score distribution vector of the ordinal basic human ratings) using Deep Convolutional Neural Network (DCNN). Conventional DCNNs which aim to minimize the difference between the predicted scalar numbers or vectors and the ground truth cannot be directly used for the ordinal basic rating distribution. Thus, a novel CNN based on the Cumulative distribution with Jensen-Shannon divergence (CJS-CNN) is presented to predict the aesthetic score distribution of human ratings, with a new reliability-sensitive learning method based on the kurtosis of the score distribution, which eliminates the requirement of the original full data of human ratings (without normalization). Experimental results on large scale aesthetic dataset demonstrate the effectiveness of our introduced CJS-CNN in this task.Comment: AAAI Conference on Artificial Intelligence (AAAI), New Orleans, Louisiana, USA. 2-7 Feb. 201

Low-crystallinity to highly amorphous copolyesters with high glass transition temperatures based on rigid carbohydrate-derived building blocks

The current trend of developing novel biobased polymeric materials is focused more on utilizing the unique structural/physical properties of renewable building blocks towards niche market applications. In this work, with the aim of developing low-crystallinity to amorphous polyesters with enhanced thermal properties, a series of copolyesters based on rigid and structurally asymmetric carbohydrate-derived building blocks, namely furan-2,5-dicarboxylic acid and isosorbide, and 1,4-butanediol were successfully synthesized using melt polycondensation. The copolyesters were obtained with varied chemical compositions and rather high molecular weights (Mn = 24 000–31 000 g mol−1) and intrinsic viscosities ([η] = 0.56–0.72 dL g−1). Incorporation of both building blocks significantly enhances the glass transition temperatures (Tg = 38–107 °C) of polyesters, and also efficiently inhibits the crystallization of the copolyesters. A low content of isosorbide (ca 10 mol%) leads to complete transition of the homopolyester to nearly fully amorphous materials. Detailed characterizations of the chemical structures and thermal properties of the synthesized copolyesters were conducted using various analytical techniques. In addition, hydrolytic and enzymatic degradations of the copolymers in the presence of porcine pancreatic lipase and cutinase were also investigated

Superabsorbent Polymers:From long-established, microplastics generating systems, to sustainable, biodegradable and future proof alternatives

Superabsorbent polymers (SAPs) play important roles in our daily life, as they are applied in products for hygiene, agriculture, construction, etc. The most successful commercially used types of SAPs are acrylate-based, which include poly(acrylic acid)s, poly(acrylamide)s, poly(acrylonitrile)s and their salts. The acrylate-based SAPs have superior water-absorbent properties, but they have high molecular weight and in addition an entirely carbon atom-based and cross-linked backbone. These factors endow them with poor (bio)degradability, which has a devastating impact on the environment where such SAP-containing materials may end up at the end of their lifetime. Furthermore, the raw materials for production of acrylate-based SAPs are mostly petroleum-based. From the viewpoint of sustainability, a bio-based resource would be the ideal candidate to replace the fossil-based ones. To overcome the shortcomings of the existing SAPs, bio-based and degradable SAPs are required. This review will then cover the following topics: (1) the technology development history and state-of-the-art of current SAPs; (2) the product designing principles of SAPs; (3) an in-depth introduction and discussion of the structural characteristics and properties of different kinds of SAPs derived from both fossil or renewable resources and (4) novel polycondensate-based, potentially biodegradable SAPs with promising industrial applicability

An Effective Lip Tracking Algorithm for Acoustic-to-Articulatory Inversion

Colloque avec actes et comité de lecture. internationale.International audienceAlthough automatic speech recognition systems can now perform well under certain conditions, they still don't provide good results in real life conditions, especially in noisy environments. Several authors have suggested that using articulatory features rather than acoustic features as a basis for speech parameterization would help yield better recognition results. The articulatory features can be recovered from the speech signal by acoustic-to-articulatory inversion. Given the acoustic signal, the recovery of the articulatory state is considered difficult. The reason is the "one-to-many" nature of the acoustic-toarticulatory inversion problem: a given articulatory state has always only one acoustic realization but an acoustic signal can be the outcome of more than one articulatory states. Since visual information is complementary to acoustic information in the inversion, lip tracking is proposed in this paper to provide visual information of lip movement for the acoustic-to-articulatory inversion. Encouraging results have proven the effectiveness of this method which provides useful information (i.e. mouth width and height) for inversion

A Robust Lip Tracking System for the Acoustic to Articulatory Inversion

Colloque avec actes et comité de lecture. internationale.International audienceThe acoustic to articulatory inversion of speech which refers to the mapping from the acoustic signal to the articulatory, is an interesting problem. Given the acoustic signal, the recovery of the articulatory state is considered difficult. The reason is the "one-to-many" nature of the acoustic-to-articulatory inversion problem: a given articulatory state has always only one acoustic realization but an acoustic signal can be the outcome of more than one articulatory states. In order to solve the one-to-many problem of the inversion, visual information complementary to acoustic signal is used. Hence, a robust lip tracking system to provide visual information (such as the width and height of mouth) for the acoustic-to-articulatory inversion is developed in this paper. The proposed approach uses a combination of motion, color and structure information of the mouth area to track lip feature points. This technique is designed to be effective and robust. It has the advantages to detect the lip feature points automatically and recover the feature points lost during tracking process. Encouraging results have been obtained using the proposed approach

Enhancement of thermoelectric performance in n-type PbTe1−ySey by doping Cr and tuning Te:Se ratio

Lead telluride and its alloys have been extensively studied for medium temperature thermoelectric applications due to decent figure-of-merit (ZT) at temperature close to 900 K. However, little emphasis has been given to improve the ZT near room temperature. In this investigation, we report a systematic study of Cr doping in PbTe[subscript 1−y]Se[subscript y] with y=0, 0.25, 0.5, 0.75, 0.85, and 1. We found the peak ZT temperature increased with increasing concentration of Se. The highest ZT of ~0.6 at room temperature in Te-rich Cr[subscript 0.015]Pb[subscript 0.985]Te[subscript 0.75]Se[subscript 0.25] was obtained due to a lowered thermal conductivity and enhanced power factor resulted from high Seebeck coefficient of about −220 µV K[superscript −1] and high Hall mobility ~1120 cm[superscript 2] V[superscript −1] s[superscript −1] at room temperature. A room temperature ZT of ~0.5 and peak ZT of ~1 at about 573–673 K is shown by Se-rich sample Cr[subscript 0.01]Pb[subscript 0.99]Te[subscript 0.25]Se[subscript 0.75]. This improvement of the room temperature ZT improved the average ZT over a wide temperature range and could potentially lead to a single leg efficiency of thermoelectric conversion for Te-rich Cr[subscript 0.015]Pb[subscript 0.985]Te[subscript 0.75]Se[subscript 0.25] up to ~11% and Se-rich Cr[subscript 0.01]Pb[subscript 0.99]Te[subscript 0.25]Se[subscript 0.75] up to ~13% with cold side and hot side temperature at 300 K and 873 K, respectively, if matched with appropriate p-type legs

Inhibition of epidermal growth factor receptor attenuates atherosclerosis via decreasing inflammation and oxidative stress

Atherosclerosis is a progressive disease leading to loss of vascular homeostasis and entails fibrosis, macrophage foam cell formation, and smooth muscle cell proliferation. Recent studies have reported that epidermal growth factor receptor (EGFR) is involved vascular pathophysiology and in the regulation of oxidative stress in macrophages. Although, oxidative stress and inflammation play a critical role in the development of atherosclerosis, the underlying mechanisms are complex and not completely understood. In the present study, we have elucidated the role of EGFR in high-fat diet-induced atherosclerosis in apolipoprotein E null mice. We show increased EGFR phosphorylation and activity in atherosclerotic lesion development. EGFR inhibition prevented oxidative stress, macrophage infiltration, induction of pro-inflammatory cytokines, and SMC proliferation within the lesions. We further show that EGFR is activated through toll-like receptor 4. Disruption of toll-like receptor 4 or the EGFR pathway led to reduced inflammatory activity and foam cell formation. These studies provide evidence that EGFR plays a key role on the pathogenesis of atherosclerosis, and suggests that EGFR may be a potential therapeutic target in the prevention of atherosclerosis development

Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging

Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of similar to 5.9% and an overall photon-chemical-electricity energy conversion efficiency of similar to 3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8V and delivers a discharge capacity of 730 mAhl(-1). Our work may guide future designs for highly efficient solar rechargeable devices