Topology-based Clusterwise Regression for User Segmentation and Demand Forecasting

Topological Data Analysis (TDA) is a recent approach to analyze data sets from the perspective of their topological structure. Its use for time series data has been limited. In this work, a system developed for a leading provider of cloud computing combining both user segmentation and demand forecasting is presented. It consists of a TDA-based clustering method for time series inspired by a popular managerial framework for customer segmentation and extended to the case of clusterwise regression using matrix factorization methods to forecast demand. Increasing customer loyalty and producing accurate forecasts remain active topics of discussion both for researchers and managers. Using a public and a novel proprietary data set of commercial data, this research shows that the proposed system enables analysts to both cluster their user base and plan demand at a granular level with significantly higher accuracy than a state of the art baseline. This work thus seeks to introduce TDA-based clustering of time series and clusterwise regression with matrix factorization methods as viable tools for the practitioner

Imaging small animal whole-body dynamics by single-impulse panoramic photoacoustic computed tomography

Small animal whole-body imaging, providing physiological, pathological, and phenotypical insights into biological processes, is indispensable in preclinical research. With high spatiotemporal resolution and functional contrast, small animal imaging can visualize biological dynamics in vivo at whole-body scale, which can advance both fundamental biology and translational medicine. However, current non-optical imaging techniques lack either spatiotemporal resolution or functional contrasts, and pure optical imaging suffers from either shallow penetration (up to ~1 mm) or a poor resolution-to-depth ratio (~1/3). Here, we present a standalone system, termed single-impulse panoramic photoacoustic computed tomography (SIP-PACT), which overcomes all the above limitations. Our technology, with unprecedented performance, is envisioned to complement existing modalities for imaging entire small animals. As an optical imaging modality, SIP-PACT captures the high molecular contrast of endogenous substances such as hemoglobin, melanin, and lipid, as well as exogenous biomarkers, at the whole animal scale with full-view fidelity. Unlike other optical imaging methods, SIP-PACT sees through ~5 cm of tissue in vivo, and acquires cross-sectional images with an in-plane resolution of ~100 μm. Such capabilities allow us to image, for the first time, mouse wholebody dynamics in real time with clear sub-organ anatomical and functional details and without motion artifacts. SIPPACT can capture transients of whole-body oxygen saturation and pulse wave propagation in vivo without labeling. In sum, we expect widespread applications of SIP-PACT as a whole-body imaging tool for small animals in fundamental biology, pharmacology, pathology, oncology, and other areas

Dry coupling for whole-body small-animal photoacoustic computed tomography

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using a whole-body small-animal ring-shaped photoacoustic computed tomography system. Dry coupling was found to provide image quality comparable to that of conventional water coupling

Secondary Production of Gaseous Nitrated Phenols in Polluted Urban Environments

Nitrated phenols (NPs) are important atmospheric pollutants that affect air quality, radiation, and health. The recent development of the time-of-flight chemical ionization mass spectrometer (ToF-CIMS) allows quantitative online measurements of NPs for a better understanding of their sources and environmental impacts. Herein, we deployed nitrate ions as reagent ions in the ToF-CIMS and quantified six classes of gaseous NPs in Beijing. The concentrations of NPs are in the range of 1 to 520 ng m(-3). Nitrophenol (NPh) has the greatest mean concentration. Dinitrophenol (DNP) shows the greatest haze-to-clean concentration ratio, which may be associated with aqueous production. The high concentrations and distinct diurnal profiles of NPs indicate a strong secondary formation to overweigh losses, driven by high emissions of precursors, strong oxidative capacity, and high NOx levels. The budget analysis on the basis of our measurements and box-model calculations suggest a minor role of the photolysis of NPs (Peer reviewe

Single-impulse panoramic photoacoustic computed tomography of small-animal whole-body dynamics at high spatiotemporal resolution

Imaging of small animals has played an indispensable role in preclinical research by providing high-dimensional physiological, pathological and phenotypic insights with clinical relevance. Yet, pure optical imaging suffers from either shallow penetration (up to ~1–2 mm) or a poor depth-to-resolution ratio (~3), and non-optical techniques for whole-body imaging of small animals lack either spatiotemporal resolution or functional contrast. Here, we demonstrate that stand-alone single-impulse panoramic photoacoustic computed tomography (SIP-PACT) mitigates these limitations by combining high spatiotemporal resolution (125 μm in-plane resolution, 50 μs per frame data acquisition and 50 Hz frame rate), deep penetration (48 mm cross-sectional width in vivo), anatomical, dynamical and functional contrasts, and full-view fidelity. Using SIP-PACT, we imaged in vivo whole-body dynamics of small animals in real time and obtained clear sub-organ anatomical and functional details. We tracked unlabelled circulating melanoma cells and imaged the vasculature and functional connectivity of whole rat brains. SIP-PACT holds great potential for both preclinical imaging and clinical translation

Vegetation Greenness Trend in Dry Seasons and Its Responses to Temperature and Precipitation in Mara River Basin, Africa

The Mara River Basin of Africa has a world-famous ecosystem with vast vegetation, which is home to many wild animals. However, the basin is experiencing vegetation degradation and bad climate change, which has caused conflicts between people and wild animals, especially in dry seasons. This paper studied the vegetation greenness (VG), vegetation greenness trends (VGT), and their responses to climate change in dry seasons in the Mara River Basin, Africa. Firstly, based on Google Earth Engine (GEE) platform and Sentinel-2 images, the vegetation distribution map of the Mara River Basin was drawn. Then dry seasons MODIS NDVI data (January to February and June to September) were used to analyze the VGT. Finally, a random forest regression algorithm was used to evaluate the response of VG and VGT to temperature and precipitation derived from ERA5 from 2000 to 2019 at a resolution of 250 m. The results showed that the VGT was fluctuating in dry seasons, and the spatial differentiation was obvious. The greenness increasing trends both upstream and downstream were significantly larger than that of in the midstream. The responses of VG to precipitation were almost twice larger than temperature, and the responses of VGT to temperature were about 1.5 times larger than precipitation. The climate change trend of rising temperature and falling precipitation will lead to the degradation of vegetation and the reduction of crop production. There will be a vegetation degradation crisis in dry seasons in the Mara River Basin in the future. Identifying the spatiotemporal changes of VGT in dry seasons will be helpful to understand the response of VG and VGT to climate change and could also provide technical support to cope with climate-change-related issues for the basin

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Data from: Facile synthesis of porous Mo2C/C composites by using luffa sponge-derived carbon template in molten salt media

Herein, we report the synthesis of a new type of porous Mo2C/C composite by using luffa sponge-derived carbon template, and ammonium molybdate ((NH4)6Mo7O24•4H2O) in the molten NaCl-KCl salts media. The product exhibits a higher specific surface area and three-dimensional porous structure, including macrochannels, micropores, and mesopores. The desirable porous structure is resulted from the carbon template structure and formed Mo2C coating

Asian crisis : balance sheet restructuring : a look at corporate restructuring and deleveraging in various industries

The Asian financial crisis of 1997-1998 had a severe negative impact on Asian economies. We analyze various financial performance indicators of companies/industries in Korea, Malaysia, Thailand, Indonesia and Singapore to assess corporate restructuring and deleveraging. Industries are airlines, construction, electronics, food, hotels, industrial commercial machinery, real estate and telecommunications