Spectroscopic Calibration for Soil N and C Measurement at a Farm Scale

AbstractCalibration modeling is necessary to implement spectroscopic measurement of soil properties. The aim of this study is to compare the performance of calibration models developed for an agricultural farmland using two spectrophotometers with different scanning ranges, e.g. 400-2100nm and 400-2500nm. Soil samples were collected from an experimental farm at Silsoe, Bedfordshire, United Kingdom. The targeted soil properties under investigation were total nitrogen (TN) and organic carbon (OC). Spectra were divided into a calibration set (75%) and an independent validation set (25%). A partial least squares regression (PLSR) with leave-one-out cross validation was carried out to build calibration models based on the two spectral ranges. Validation result shows that the PLSR models developed on the range of 400-2500nm outperform those on 400-2100nm. It suggests that wavelengths located in the spectral band of 2100-2500nm contribute to model calibration of soil N and C. It is concluded that spectroscopic calibration using 400-2500nm could produce higher prediction accuracy for soil N and C measurement at a farm scale than short spectral ranges

Feasibility Study of a Campus-Based Bikesharing Program at UNLV

Bikesharing systems have been deployed worldwide as a transportation demand management strategy to encourage active modes and reduce single-occupant vehicle travel. These systems have been deployed at universities, both as part of a city program or as a stand-alone system, to serve for trips to work, as well as trips on campus. The Regional Transportation Commission of Southern Nevada (RTCSNV) has built a public bikesharing system in downtown Las Vegas, approximately five miles from the University of Nevada, Las Vegas (UNLV). This study analyzes the feasibility of a campus-based bikesharing program at UNLV. Through a review of the literature, survey of UNLV students and staff, and field observations and analysis of potential bikeshare station locations, the authors determined that a bikesharing program is feasible at UNLV

Attitudes and Behavioral Response Toward Key Tobacco Control Measures from the FCTC among Chinese Urban Residents

BACKGROUND. The Chinese National People's Congress ratified the WHO Framework Convention on Tobacco Control (FCTC) on 27 August 2005, signaling China's commitment to implement tobacco control policies and legislation consistent with the treaty. This study was designed to examine attitudes towards four WHO FCTC measures among Chinese urban residents. METHODS. In a cross-sectional design study, survey data were collected from two Chinese urban cities involving a sample of 3,003 residents aged 15 years or older. Through a face-to-face interview, respondents were asked about attitudes toward four tobacco control measures developed by the WHO FCTC. Data on the four dependent measures were analyzed using multivariate logistic regression analyses. Using descriptive statistics, potential change in smoking behavior that smokers might make in response to increasing cigarette prices is also reported. RESULTS. 81.8% of the respondents in the study sample supported banning smoking in public places, 68.8% favored increasing the cigarette tax, 85.1% supported health warnings on cigarette packages, and 85.7% favored banning tobacco advertising. The likelihood to support these measures was associated with gender, educational level, and personal income. Smokers were less likely to support these measures than non-smokers, with decreased support expressed by daily smokers compared to occasional smokers, and heavy smokers compared to light smokers. The proportion of switching to cheaper cigarette brands, decreasing smoking, and quitting smoking altogether with increased cigarette prices were 29.1%, 30.90% and 40.0% for occasional smokers, respectively; and 30.8%, 32.7% and 36.5% for daily smokers, respectively. CONCLUSION. Results from this study indicate strong public support in key WHO FCTC measures and that increases in cigarette price may reduce tobacco consumption among Chinese urban residents. Findings from this study have implications with respect to policymaking and legislation for tobacco control in China

Moir\'e Magnetic Exchange Interactions in Twisted Magnets

Besides moir\'e superlattice, twisting can also generate moir\'e magnetic exchange interactions (MMEIs) in van der Waals magnets. However, due to the extreme complexity and twist-angle-dependent sensitivity, all existing models fail to capture the MMEIs, preventing the understanding of MMEIs-induced new physics. Here, we develop a microscopic moir\'e spin Hamiltonian that enables the effective description of MMEIs via a sliding-mapping approach in twisted magnets, as demonstrated in twisted bilayer CrI3. Unexpectedly, we discover that the emergence of MMEIs can create an unprecedented magnetic skyrmion bubble (SkB) with non-conversed helicity, named as moir\'e-type SkB, representing a unique spin texture solely generated by MMEIs and ready to be detected under the current experimental conditions. Importantly, the size and population of SkBs can be finely controlled by twist angle, a key step for skyrmion-based quantum computing and information storage. Furthermore, we reveal that the MMEIs can be effectively manipulated by the substrate-induced interfacial Dzyaloshinskii-Moriya interaction, modulating the twist-angle-dependent magnetic phase diagram, which solves the outstanding disagreements between prior theories and experiments and verifies our theory.Comment: 17 pages, 5 figure

The impact of land use/cover change on extreme temperatures on the Yangtze River Delta, China

The contribution from land use/cover change (LUCC) toward temperature in recent decades is of great concern across the globe. Although there have been many studies, most of them focus on the discussion of average temperature and lack a discussion of extreme temperatures. In this study, we first investigated the spatio-temporal changes in extreme temperatures in the Yangtze River Delta during 1980–2020 using the ensemble empirical mode decomposition (EEMD) method. Then, we explored the impact of LUCC on extreme temperatures using the observation minus reanalysis (OMR) method. Finally, the relationship between the normalized difference vegetation index (NDVI) and extreme temperatures was analyzed using the correlation analysis method. We found that: (1) extreme temperatures have a nonlinear variation characteristics on different time scales. Extremely high temperatures (EHT) clearly exhibited a monthly time scale (quasi-3-month), an interannual time scale (quasi-1-year, quasi-2-year, quasi-3-year and quasi-5-year), and an interdecadal time scale (quasi-10-year and quasi-35-year). Extremely low temperatures (ELT) also clearly exhibited a monthly time scale (quasi-3-month), an interannual scale (quasi-1-year, quasi-2-year, quasi-3-year and quasi-6-year), and an interdecadal scale (quasi-10-year and quasi-20-year). (2) EHT showed an east–middle–west staggered phase and ELT showed a southeast–northwest anti-phase characteristic in spatial distribution. (3) The contribution rates of LUCC on EHT and ELT are 53.6% and 92.4%, respectively, which are higher than for the average temperature (40%). (4) The monthly time scale response of the NDVI to extreme temperatures is more regionally concentrated and significant than that on the interannual time scale in spatial distribution. This paper makes up for the insufficiency of the impact of land use/cover changes on extreme temperature changes at multiple time scales and enriches our understanding of climate change

Ultra-Sensitive Piezo-Resistive Sensors Constructed with Reduced Graphene Oxide/Polyolefin Elastomer (RGO/POE) Nanofiber Aerogels.

Flexible wearable pressure sensors have received extensive attention in recent years because of the promising application potentials in health management, humanoid robots, and human machine interfaces. Among the many sensory performances, the high sensitivity is an essential requirement for the practical use of flexible sensors. Therefore, numerous research studies are devoted to improving the sensitivity of the flexible pressure sensors. The fiber assemblies are recognized as an ideal substrate for a highly sensitive piezoresistive sensor because its three-dimensional porous structure can be easily compressed and can provide high interconnection possibilities of the conductive component. Moreover, it is expected to achieve high sensitivity by raising the porosity of the fiber assemblies. In this paper, the three-dimensional reduced graphene oxide/polyolefin elastomer (RGO/POE) nanofiber composite aerogels were prepared by chemical reducing the graphene oxide (GO)/POE nanofiber composite aerogels, which were obtained by freeze drying the mixture of the GO aqueous solution and the POE nanofiber suspension. It was found that the volumetric shrinkage of thermoplastic POE nanofibers during the reduction process enhanced the compression mechanical strength of the composite aerogel, while decreasing its sensitivity. Therefore, the composite aerogels with varying POE nanofiber usage were prepared to balance the sensitivity and working pressure range. The results indicated that the composite aerogel with POE nanofiber/RGO proportion of 3:3 was the optimal sample, which exhibits high sensitivity (ca. 223 kPa-1) and working pressure ranging from 0 to 17.7 kPa. In addition, the composite aerogel showed strong stability when it is either compressed with different frequencies or reversibly compressed and released 5000 times