Evaluating ecohydrological modelling framework to link atmospheric CO2 and stomatal conductance

The establishment of an accurate stomatal conductance (gs) model in responding to CO2 enrichment under diverse environmental conditions remains an important issue as gs is the key to understand the plant–water–atmosphere interactions. A better representation of gs is important to reduce uncertainties in predicting the climate change impacts on various ecosystem functions. In this study, we evaluated three most commonly used gs formulations for the estimation of the stomatal response to environmental factors using in situ measurements under different environmental conditions. The three gs models were Leuning's modified Ball–Berry model and two specific cases of the optimization models (i.e., Rubisco limitation model and RuBP regeneration limitation model). On the basis of an analysis of 234 data points obtained from experiments under instantaneous, semicontrolled, and the free‐air CO2 experiment conditions, we found that Leuning's modified Ball–Berry model and RuBP‐limited optimization model showed similar performance, and both performed better than Rubisco limitation model. Functional groups (e.g., C3 vs. C4 species) and life form (e.g., annual vs. perennial species) play an important role in determining the gs model performance and thus pose a challenge for gs predictions in mixed vegetation communities

2d Regional Correlation Analysis Of Single-molecule Time Trajectories

We report a new approach of 2D regional correlation analysis capable of analyzing fluctuation dynamics of complex multiple correlated and anticorrelated fluctuations under a noncorrelated noise background. Using this new method, by changing and scanning the start time and end time along a pair of fluctuation trajectories, we are able to map out any defined segments along the fluctuation trajectories and determine whether they are correlated, anticorrelated, or noncorrelated; after which, a cross-correlation analysis can be applied for each specific segment to obtain a detailed fluctuation dynamics analysis. We specifically discuss an application of this approach to analyze single-molecule fluorescence resonance energy transfer (FRET) fluctuation dynamics where the fluctuations are often complex, although this approach can be useful for analyzing other types of fluctuation dynamics of various physical variables as well

Social Media Use Purposes and Psychological Wellbeing in Times of Crises

This study investigates the effect of social media (SM) use purposes and user characteristics on individual psychological wellbeing (PWB) during the coronavirus pandemic (COVID-19). Informed by the uses and gratifications theory and PWB research, this study analyzed survey data collected from 282 SM users aged 18 through 59 from a minority-serving university in the United States in March-April 2020. Our quantitative data analysis showed that social media can be used to improve the quality of personal experiences during the COVID-19 crisis through three mechanisms—connectedness (i.e., social), engagement (i.e., collaborative), and entertainment (i.e., hedonic). However, the effect varied by gender, SM usage level, and individual concern about COVID-19 risk. The findings contribute to the literature and offer implications in technology use for enhancing public mental health during crises

Elevated CO2 as a driver of global dryland greening.

While recent findings based on satellite records indicate a positive trend in vegetation greenness over global drylands, the reasons remain elusive. We hypothesize that enhanced levels of atmospheric CO2 play an important role in the observed greening through the CO2 effect on plant water savings and consequent available soil water increases. Meta-analytic techniques were used to compare soil water content under ambient and elevated CO2 treatments across a range of climate regimes, vegetation types, soil textures and land management practices. Based on 1705 field measurements from 21 distinct sites, a consistent and statistically significant increase in the availability of soil water (11%) was observed under elevated CO2 treatments in both drylands and non-drylands, with a statistically stronger response over drylands (17% vs. 9%). Given the inherent water limitation in drylands, it is suggested that the additional soil water availability is a likely driver of observed increases in vegetation greenness

Probing Single-molecule Interfacial Electron Transfer Dynamics Of Porphyrin On Tio2 Nanoparticles

Single-molecule interfacial electron transfer (ET) dynamics has been studied by using single-molecule fluorescence spectroscopy and microscopic imaging. For a single-molecule zinc-tetra (4-carboxyphenyl) porphyrin (ZnTCPP)/TiO2 nanoparticle system, the single-molecule fluorescence trajectories show strong fluctuation and blinking between bright and dark states. The intermittency and fluctuation of the single-molecule fluorescence are attributed to the variation of the reactivity of interfacial electron transfer. The nonexponential autocorrelation function and the power-law distribution of the probability density of dark times imply the dynamic and static inhomogeneities of the interfacial ET dynamics. On the basis of the power-law analysis, the variation of single-molecule interfacial ET reactivity is analyzed as a fluctuation according to the Levy statistics

Suspended Lipid Bilayer For Optical And Electrical Measurements Of Single Ion Channel Proteins

Making and holding an artificial lipid bilayer horizontally in an aqueous solution within the microscopic working distance of similar to 100 mu m are essential for simultaneous single molecule imaging and single ion-channel electrical current recording. However, preparation of such a lipid bilayer without a solid support is technically challenging. In a typical supported lipid bilayer, the asymmetric local environments and the strong perturbation of the underneath solid or dense surface can diverge the normal behavior of membrane proteins and lipids. On the other hand, the suspended lipid bilayers can provide a native local environment for the membrane proteins and lipids by having fluids on both sides. In this technical report, we present a simple and novel methodology for making a suspended lipid bilayer that can be used for recording the single-molecule diffusion and single ion-channel electrical measurements of ion-channel proteins. Our approach has a higher validity for studying the molecular diffusions and conformational fluctuations of membrane proteins without having perturbations from supporting layers. We demonstrate the feasibility of such an approach on simultaneous single-molecule fluorescence imaging and electric current measurements of ion channel proteins

Phononic transport in 1T prime-MoTe2: anisotropic structure with an isotropic lattice thermal conductivity

Molybdenum ditelluride (MoTe2) is an unique transition metal dichalcogenide owing to its energetically comparable 1H and 1T prime phases. This implies a high chance of coexistence of 1H-1T prime heterostructures which poses great complexity in the measurement of the intrinsic lattice thermal conductivities (kappa). In this work, via first-principles calculations, we examine the lattice-wave propagation and thermal conduction in this highly structurally anisotropic 1T prime MoTe2. Our calculation shows that the 1T prime phase has a sound velocity of 2.13 km/s (longitudinal acoustic wave), much lower than that of the 1H phase (4.05 km /s), indicating a staggered transmission of lattice waves across the boundary from 1H to 1T prime phase. Interestingly, the highly anisotropic 1T prime MoTe2 shows nearly isotropic and limited kappa_L of 13.02 W/mK, owing to a large Gruneisen parameter of acoustic flexural mode, heavy masses of Mo and Te elements and a low phonon group velocity. Accumulative kappa_L as a function of mean free path (MFP) indicates phonons with MFP less than ~300 nm contribute 80% of kappa_L and an inflection point at ~600 nm. Our results will be critical for understanding of the size dependent kappa_L of nanostructured 1T prime MoTe2

Evolving to Type Ia Supernovae with Short Delay Times

The single-degenerate model is currently a favourable progenitor model for Type Ia supernovae (SNe Ia). Recent investigations on the WD + He star channel of the single-degenerate model imply that this channel is noteworthy for producing SNe Ia. In this paper we studied SN Ia birthrates and delay times of this channel via a detailed binary population synthesis approach. We found that the Galactic SN Ia birthrate from the WD + He star channel is $\sim 0.3\times 10^{-3} {\rm yr}^{-1}$ according to our standard model, and that this channel can explain SNe Ia with short delay times ($\sim4.5\times10^7 - 1.4\times10^8$ yr). Meanwhile, these WD + He star systems may be related to the young supersoft X-ray sources prior to SN Ia explosions.Comment: 7 pages, 5 figures, 1 table, accepted for publication in Ap