Abstract: The causes of many blade fractures of a steam turbine in a power plant were analyzed by means of macro analysis, mechanical examination, metallographic examination, SEM and X-ray fluorescence spectrum analysis(XRF). The results show that the blade cracks due to corrosion fatigue. Cl -, K +, etc. react with the turbine blades in the steam environment in physical, chemical and electrochemical ways, causing local spot corrosion on the blades, forming corrosion pits.In addition, the steam condensate has an erosion effect on the blades, both of which form a corrosion fatigue source. The autocatalytic process of block cell is formed when Cl -, K +, etc. react with the turbine blades. Under the action of complex load, the current density i of activation dissolution of metal can be expressed as a function of complex stress state .Crack growth has an important relationship with stress, depth and width of corrosion pits. The larger the width of corrosion pit is, the deeper the depth is, the smaller threshold nominal stress range for crack elongation 〖∆σ〗_th is, the easier the blade cracks. Under the external conditions of complex alternating stress formed by tensile force, bending force, torsion force and exciting force, the complex alternating stress directly promotes the crack propagation until the fracture failure. Keywords:XRF;Corrosion fatigue;Corrosion pit;Threshold nominal stress range for crack elongation 〖∆σ〗_th;Complex alternating stress

Accurate prediction of protein secondary structure (alpha-helix, beta-strand and coil) is a crucial step for protein inter-residue contact prediction and ab initio tertiary structure prediction. In a previous study, we developed a deep belief network-based protein secondary structure method (DNSS1) and successfully advanced the prediction accuracy beyond 80%. In this work, we developed multiple advanced deep learning architectures (DNSS2) to further improve secondary structure prediction. The major improvements over the DNSS1 method include (i) designing and integrating six advanced one-dimensional deep convolutional/recurrent/residual/memory/fractal/inception networks to predict secondary structure, and (ii) using more sensitive profile features inferred from Hidden Markov model (HMM) and multiple sequence alignment (MSA). Most of the deep learning architectures are novel for protein secondary structure prediction. DNSS2 was systematically benchmarked on two independent test datasets with eight state-of-art tools and consistently ranked as one of the best methods. Particularly, DNSS2 was tested on the 82 protein targets of 2018 CASP13 experiment and achieved the best Q3 score of 83.74% and SOV score of 72.46%. DNSS2 is freely available at: https://github.com/multicom-toolbox/DNSS2.

Olivia J. MurphySubmitted 9 Mar 20201085 wordsConscious will may be the cause of an action or the apparent cause of an action. Determinism states that it is the latter, whereas free will states the opposite (Wegner, D.M., 2002). Determinism implies that humans are not in control of their actions, but rather under the illusion that they have control. Both sides of the debate offer credible evidence, but much of the results from research in this area are still inconclusive. For example, it is not possible to determine which area of the brain the experience of will occurs at (Wegner, D.M., 2002). Therefore, it is difficult to determine the true nature of the cause of an individual’s actions. However, it is possible that free will and determinism co-occur equally or at differing percentages. That is, human actions may be due to an individual’s thoughts as well as predetermined factors that one is unaware of. If the actions of humans are indeed predetermined, then it becomes possible to accurately predict the decisions that a person will make. On the other hand, if free will truly exists alone, then actions would be unpredictable by a third party. Lifetime events may be easier to predict than daily events. It is dependent on the certainty with which one can conclude that an event is predetermined. There are many variables that affect this certainty, including dispositional and situational factors.Dispositional factors having a large impact on human behaviour would support the notion of determinism. Zautra A. J. et al. (1991) showed that personality has little to do with the causation of daily events in older adults, suggesting that actions may be triggered by thoughts and are not predetermined. Contrary to this notion, it has been shown that psychological stress levels can be anticipated by personality in people of all ages, helping to predict major life events such as depressive episodes (Kendler, K. S. et al., 2004). It is possible, however, that the personality that correlates with the depressive episodes is a result of the depressive episodes rather than the cause of them. If this is the case, then personality would be ruled out as a significant indicator of psychological stress. However, this does not account for factors such as context, which may also play a role in determining a person’s behaviour. Situational factors may determine how well a person copes with life as well as whether a female will confront gender discrimination or not (Ayres, M. M. et al., 2009; Fabes, R. A., & Eisenberg, N., 1997). This proves that although dispositional factors may be a weak predictor of daily life events, this is not the case for situational factors. Everyday behaviour in students in particular has been shown to be strongly influenced by situational factors including positive reinforcement and availability of support services (Jackson, Y., & Warren, J. S., 2000). It seems that context is an important predictor of behaviour for children and adults. Other than these internal and external factors, other causal factors exist in the anticipation of human behaviour.Wegner (2002) lists a number of “alternatives to thoughts as causes for actions” such as impulse and emotion. From this, he endeavours to explain that actions which are due to strong emotion lack voluntariness. Furthermore, he implies that actions are not largely a result of our thoughts and that we are being deceived when we attribute our actions to free will. On the contrary, it is very possible that impulsive actions, including those that are widely accepted as involuntary such as yawning, may be partly or largely voluntary. One could argue that emotions are heavily driven by our thoughts. Nussbaum (2001) goes as far as to refer to emotions as “upheavals of thoughts”. This would suggest that impulsive actions, which are due to emotions, are in fact due to intense thoughts. Thoughts may therefore be the cause of impulsive actions which may make these actions partly voluntary. Additionally, those with Autism Spectrum Disorder are said to struggle when it comes to feeling empathy (Department of Life, Health and Environmental Sciences, University of L’Aquila, 2014). As well as this, they are significantly less likely to yawn contagiously (Senju, A. et al., 2007). Furthermore, it is believed by some that yawning may be largely due to feelings of empathy (Palagi, E. et al., 2009). It can be construed from this that yawning, an impulsive action, may be caused by an “upheaval of thoughts” (Nussbaum, M.C., 2003), making it a voluntary action. However, this would not be labelled as part of conscious free will, as we are unaware of the appearance of the urge to yawn before it appears (Wegner 2020). The evidence supports the notion that there may be merit to both the impression that we have control over our actions and the impression that it is actually an illusion. Therefore, actions may be partially under an individual’s own conscious control, and partially unconscious. However, other research suggests otherwise.The order of events when performing an action is crucial when it comes to the debate of determinism and free will. If conscious will were to be experienced prior to the biological processes involved in acting out a movement, then free will would likely be a reality. On the other hand, if research were to show that the body prepares for action even milliseconds before the individual becomes aware of deciding to perform that action, then it would be very likely that all actions are indeed predetermined. In reality, the latter appears to be true, as “conscious will kicks in after the brain has already started preparing for the action” (Wegner, 2002). This strongly points to determinism and could completely rule out the possibility that free will exists. However, there have been little replications of the experiment used to unearth this evidence and therefore its credibility can be questioned (Wegner, 2002). It seems that although research strongly suggests predetermination of actions, more research is required to stabilize the determinism claim and determine if human behaviour can in fact be predicted accurately.It is clear that there is not enough evidence to conclude whether free will exists or not. Further research is required to determine to what length the behaviour of others can be predicted and how accurate these predictions can be. Evidence points towards a combination of predeterminism and conscious choice, which suggests that some behaviour can be predicted. In particular, external factors influence the daily life events of individuals and allow us to make predictions, whilst internal factors are possibly an influence for major life events.Ayres, M. M., Friedman, C. K., & Leaper, C. (2009). Individual and situational factors related to young women’s likelihood of confronting sexism in their everyday lives. Sex Roles , 61 . doi.: 10.1007/s11199-009-9635-3Department of Life, Health and Environmental Sciences, University of L’Aquila. (2014). Affective and cognitive empathy in adolescents with autism spectrum disorder. Frontiers, 8 . doi.: 10.3389/fnhum.2014.00791Fabes, R. A., & Eisenberg, N. (1997). Regulatory control and adults’ stress-related responses to daily life events. Journal of personality and social psychology , 73 . doi.: 10.1037/0022-3514.73.5.1107Jackson, Y., & Warren, J. S. (2000). Appraisal, social support, and life events: Predicting outcome behavior in school‐age children.Child development , 71 . doi.: 10.1111/1467-8624.00238Kendler, K. S., Kuhn, J., & Prescott, C. A. (2004). The interrelationship of neuroticism, sex, and stressful life events in the prediction of episodes of major depression. American Journal of Psychiatry , 161 . doi.: 10.1176/appi.ajp.161.4.631Nussbaum, M.C. (2003). Upheavals of thought: The intelligence of emotion . (pg. 2). Cambridge University Press.Palagi, E., Leone, A., Mancini, G., & Ferrari, P.F. (2009). Contagious yawning in gelada baboons as a possible expression of empathy.Proceedings of the National Academy of Sciences of the United States of America, 46 . doi.: 10.1073/pnas.0910891106Senju, A., Maeda, M., Kikuchi, Y., Hasegawa, T., Tojo, Y., & Osanai, H. (2007). Absence of contagious yawning in children with Autism Spectrum Disorder. The Royal Society Publishing, 6 . doi.: 10.1098/rsbl.2007.0337Wegner, D.M. (2002). The illusion of conscious will . Massachusetts Institute of Technology.Zautra A. J., Finch, J.F., Reich, J.W., & Guamaccia, C.A. (1991). Predicting the everyday life events of older adults. Journal of Personality, 59 . doi.: 10.1111/j.1467-6494.1991.tb00258.x

It is important for drought risk assessment and sustainable development of water resources on the basis of understanding the spatio-temporal characteristics of drought and return period. This study introduced a new drought index, standardized supply-demand water index (SSDI), and a run theory which are applied to identify ecological drought events and parameters (e.g. duration, severity, peak and coverage area) in the Yangtze River Source Region (YRSR). And the bivariate probability and return period were calculated via 2-dimensional joint copula to investigate the drought-prone regions. The results indicate that: (1) Compared with traditional meteorological drought index, the SSDI is reliable and can reflect the comprehensive characteristics of the ecological drought information more easily and effectively; (2) The YRSR had witnessed the most severe drought episodes in the periods of late-1970s, mid-1980s and mid-1990s, but the SSDI showed a wetting trend since mid-2000s. And droughts in the Southern YRSR were relatively more severe with longer drought duration; (3) In most areas of Togton River Basin and Dam River Basin, the severe ecological drought events happened more frequently; (4) Drought duration and severity in the YRSR were more susceptible to temperature when the temperature rise were above 1.0°C. The average drought duration and severity increased by 20.7% and 32.6% with a temperature rise of 1°C.

Extreme droughts of increased frequency due to climate change poses great challenges to the sustainability of plantations in drylands worldwide. Millions of plantations on China’s Loess Plateau which are mainly in drylands are threatened by serious degradation due to water scarcity. Here we aim to disentangle the impacts of combinations of terracing and mulching on water use strategy and its response to extreme droughts in a rainfed jujube (Ziziphus jujuba) plantation on the semiarid Loess Plateau, using three-year in situ field observations. Pruned jujube branches and maize straw were mulched on half-moon terraces to form two combined treatments, referred to as JBT and MST, respectively. The efficacy of these two combinations on the water use strategy of jujube trees was compared with terracing alone (SHT) and control (no terrace). We found that extreme drought clearly reduced soil water storage (SWS) under all treatments. However, the combined treatments showed significantly (P<0.05) higher SWS than the SHT and control. Furthermore, the combined treatments enhanced soil water use in deep layers during both normal and drought years, thus helping jujube trees to resist droughts. Moreover, the extreme drought significantly reduced transpiration whereas the moderate drought increased transpiration at both seasonal and annual scales. Nonetheless, the combined treatments were associated with enhanced transpiration compared to the SHT and control during drought periods. Finally, jujube trees exhibited isohydric behavior which also helped them to cope with prolonged droughts. Overall, the findings here may provide insights into land management of dryland plantations worldwide under climate change.

Many studies highlight the key role that farmers play in combating soil erosion, and measure their willingness to adopt sustainable cultivation practices in front of a monetary compensation. However, only a few of them focus on factors affecting the magnitude of such compensations, despite this information is crucial in the design and implementation of public supported actions aimed at combating agricultural land desertification. We try to contribute to fill this empirical gap by reporting results of a research carried out to investigate what factors influencing farmers’ compensation request for combating soil erosion in a significant Mediterranean cropland area. Using a discrete choice experiment, we measured cereal growers’ marginal compensation for adopting soil conservation practices. Then, using a post-estimation analysis based on a Seeming Unrelated REgression (SURE) model, we identified and analysed which farm’s and farmers characteristics significantly influenced the requested compensations. This post estimation analysis proved that farmers’ motivations, opinions and currently undertaken cultivation practices matter.

Molecular typing results are not routinely used for CHD. Aiming to uncover the underlying molecular features for different types of CHD, we screened the differentially expressed genes (DEGs) associated with CHD based on the GEO data and expanded in the NCBI-gene and OMIM databases to finally obtain 2021 DEGs. Then the weighted gene co-expression analysis (WGCNA) was performed on the candidate genes, and 6 distinctive WGCNA modules were identified, 2 of which were associated with CHD. Moreover, DEGs were mined as key genes for co-expression based on the module network relationship. Furthermore, the differential miRNAs of CHD and interactions in the database were mined in the GEO dataset to build a multi-factor regulatory network of key genes for co-expression. Combined these results, the CHD samples were further classified into 5 clusters by using the module core genes, and we defined FTH1, HCAR3, RGS2, S100A9 and TYROBP 5 genes in different subgroups. Finally, FTH1, S100A9 and TYROBP were significantly increased while HCAR3 decreased in mRNA level in CHD patients’ blood where RGS2 was hardly determined. In conclusion, the screened core clusters of genes may be potential target for diagnosis and treatment of CHD as a molecular typing module.

This paper present an accurate numerical algorithm to solve the space fractional-order Fisher’s equation where the derivative operator is described in the Caputo derivative sense. In the presented discretization process, first we use the compact nite difference (CFD) to occur a semi-discrete in time derivative, and implement the Chebyshev spectral collocation method (CSCM) of the third-kind to discretize the spatial fractional derivative. The presented method converts the studied problem to be a system of algebraic equations which can be easily solved. To study the convergence and stability analysis, some theorems are given with their profs. A numerical simulation is given to test the accuracy and the applicability of our presented algorithm.

In this paper, the relativistic Toda lattice (RTL) equation is investigated via N-fold Darboux transformation (DT) technique. Basing on the Lax pair and gauge transformation, we construct N-fold DT of the RTL equation, and derive two kinds of the N-fold explicit exact solutions from two different seed solutions. Structures of the one-, two-, three- and four-soliton solutions and periodic solutions which have important applications are shown graphically. By studying the elastic interactions among four-soliton solutions, we confirm those solutions’ shapes and amplitudes don’t change after the interaction, which are the main characteristics of solitons. In particular, we present the relationship between the structures of exact solutions and the parameters with N=1. Results in this paper might be helpful for interpreting certain physical phenomena.

This article focuses on studying mild solutions of an original frac- tional partial differential equation disturbed by multiplicative white noise. We employ techniques of semi group theory, Hausdorff measure, and Darbo xed point theorem.

In this paper, we consider an electromagnetic obstacle scattering problem in a piecewise homogeneous medium. We assume that the incident field is the electromagnetic plane wave and the obstacle consists of metallic and nonmetallic parts. We firstly establish uniqueness and existence for the solution to the electromagnetic obstacle scattering problem. Then we prove that the electric far field pattern satisfies the reciprocity relation and the set of electric far field patterns is complete in a Hilbert space. These results have an important bearing on the solution of the inverse electromagnetic scattering problem i.e. determination of the shape of the obstacle from the knowledge of the electric far field patterns.

The lower bound decay rate of global solution to the compressible viscous quantum magnetohydrodynamic model in three-dimensional whole space under the $H^5\times H^4\times H^4$ framework is investigated in this paper. We firstly show that the lower bound of decay rate for the density, velocity and magnetic field converging to the equilibrium state (1,0,0) in $L^2$-norm is $(1+t)^{-\frac{3}{4}}$ when the initial data satisfies some low frequency assumption. Moreover, we prove that the lower bound of decay rate of $k(k\in [1,3])$ order spatial derivative for the density, velocity and magnetic field converging to the equilibrium state (1,0,0) in $L^2$-norm is $(1+t)^{-\frac{3+2k}{4}}$. Then we show that the lower bound of decay rate for the time derivatives of density and velocity converging to zero in $L^2$-norm is $(1+t)^{-\frac{5}{4}}$, but the lower bound of decay rate for the time derivative of magnetic field converging to zero in $L^2$-norm is $(1+t)^{-\frac{7}{4}}$.

A new four-component nonlinear Schrödinger equation is first proposed in this work and studied by Riemann-Hilbert approach. Firstly, we derive a Lax pair associated with a $5\times5$ matrix spectral problem for the four-component nonlinear Schrödinger equation. Then based on the Lax pair, we analyze the spectral problem and the analytical properties of the Jost functions, from which the Riemann-Hilbert problem of the equation is successfully established. Moreover, we obtain the $N$-soliton solutions of the equation by solving the Riemann-Hilbert problem without reflection. Finally, we derive two special cases of the solutions to the equation for $N=1$ and $N=2$, and the local structure and dynamic behavior of the one-and two-soliton solutions are analyzed graphically.

A sharper uncertainty inequality which exhibits a lower bound larger than that in the classical N-dimensional Heisenberg’s uncertainty principle is obtained, and extended from N-dimensional Fourier transform domain to two N-dimensional fractional Fourier transform domains. The conditions that reach the equality relation of the uncertainty inequalities are deduced. Example and simulation are performed to illustrate that the newly derived uncertainty principles are truly sharper than the existing ones in the literature. The new proposals’ applications in time-frequency analysis and optical system analysis are also given.

We are concerned with the following polyharmonic equation: \begin{equation*} \Delta_p^L u+V(x)|u|^{p-2}u = K(x)f(x,u) and u>0 in \Bbb R^N, \end{equation*} where $1< p<\infty$, $N>Lp$, $L=1,2,\cdots$ and the potential functions $V, K:\Bbb R^{N}\to(0,\infty)$ are continuous. We study the existence and multiplicity of nontrivial positive weak solutions for the problem above via mountain pass theorem and fountain theorem.

In this paper, using the Lyapunov-like functions, the practical stability with respect to part of the variables of fractional-order nonlinear systems depending on a small parameter is studied.

This paper proposes a seven-compartment Markov decision process model for control of epidemic infections. Decision variables include vaccination, treatment, and quarantine. Cost function includes cost of treatment, cost of quarantine, and cost of vaccination. Transition probabilities have been represented by Bayesian network. Scalability of the proposed model has been discussed. Extensions of the proposed approach has also been included as well as comparison with the existing models. Superiority of the proposed approach has been elaborated through a case study.

We investigate mixed type boundary-transmission problems of the generalized thermo-electro-magneto elasticity (GTEME) theory for complex elastic anisotropic layered structures containing interfacial cracks. This type of problems are described mathematically by systems of partial differential equations with appropriate transmission and boundary conditions for six dimensional unknown physical field (three components of the displacement vector, electric potential function, magnetic potential function, and temperature distribution function). We apply the potential method and the theory of pseudodifferential equations and prove uniqueness and existence theorems of solutions to different type mixed boundary-transmission problems in appropriate Sobolev spaces. We analyze smoothness properties of solutions near the edges of interfacial cracks and near the curves where different type boundary conditions collide.

The widespread construction of photovoltaic (PV) power stations within northwest China poses an environmental threat because of severe wind erosion and land degradation attributed to unique wind control issues caused by the power stations. In this study, various engineering (E), plant (V), and biocrust (B) treatments were evaluated for their effectiveness in the reduction of wind erosion. The placement of solar panels with wide wind inlets and narrow wind outlets caused wind velocity reductions at the inlet that sharply increased at the outlet and formed distinct zones of deflation, direct shear abrasion (DSA), and deposition. The engineering treatments reduced the wind velocities and sand transport rates, in comparison to the control with E4 (DSA zone + a gravel/deposition zone + red clay) being the most effective with an 87% reduction in the total sand transport rate. Both plant treatments V1 (Sedum aizoon L.) and V2 (Pennisetum alopecuroides (L.) Spreng) increased the aerodynamic roughness, and decreased the sand transport rates and the sand erosion-deposition budget under or between the solar panels. Treatment B2 (moss crust) decreased the sand transport rate and sand erosion-deposition budget under the solar panels in comparison to the control. All the treatments had effects on reducing wind erosion, and we strongly recommend the use of moss crust, gravel mulch, and red clay mulch in the deflation zones, DSA zones, and deposition zones, respectively, to control the severe wind erosion at these PV power stations located in sandy areas.

Droplet impact on a hydrophobic surface is considered and the influence of the droplet volume on the impact characteristics is analyzed. Pressure variation and the characteristics of the droplet in the spreading and retraction cycles are numerically predicted incorporating the conditions adopted in the experiments. The dynamics of the impacting droplet on the hydrophobic surface is simulated and the impacting droplet motion is recorded using the high speed recording system. It is found that the numerical predictions of the impacting droplet shape and height ratios during the spreading and the contraction cycles are in good agreement with those of the experimental data. Increasing droplet volume increases: i) the peak pressure in the droplet fluid upon the impact and ii) the transition period of the droplet on the hydrophobic surface. Increasing droplet volume enhances peak velocity of the droplet spreading on the surface.

We use adaptive dynamics models to study how changes in the abiotic environment affect patterns of evolutionary dynamics and diversity in evolving communities of organisms with complex phenotypes. The models are based on the logistic competition model and environmental changes are implemented as a temporal change of the carrying capacity as a function of phenotype. In general we observe that environmental changes cause a reduction in the number of species, in total population size, and in phenotypic diversity. The rate of environmental change is crucial for determining whether a community survives or undergoes extinction. Until some critical rate of environmental changes, species are able to follow evolutionarily the shifting phenotypic optimum of the carrying capacity, and many communities adapt to the changing conditions and converge to new stationary states. When environmental changes stop, such communities gradually restore their initial phenotypic diversity.

Background and purpose: Being exposed to acute stress may cause people to behave more habitual, which purportedly is associated stress-induced increased dopamine release. In contrast, experimental rises in systemic dopamine levels have been shown to increase goal-directed behaviour and, thus, decrease habitual control. Whether experimentally increased dopamine functioning can modulate stress-induced reductions in goal-directed behaviour and its neural substrates, is currently unknown. Experimental approach: To assess whether increased dopamine functioning reduces stress effects on goal-directed behaviour, 100 participants were recruited who were randomly assigned to one of four conditions in a 2x2 between participants design. Participants underwent a stress induction protocol (Maastricht Acute Stress Test; MAST) or a control procedure and received methylphenidate (40 mg, oral) or placebo. In a well-established instrumental learning paradigm, participants were trained to learn stimulus-response-outcome associations, after which rewards were selectively devalued and participants’ goal-directed behaviour was assessed at peak cortisol/methylphenidate concentrations in a magnetic resonance imaging scanner to assess brain activation. Key results: The MAST effectively increased physiological measures of stress (salivary cortisol, blood pressure) and subjective stress. Methylphenidate also increased cortisol levels over time. While stress selectively reduced goal-directed behaviour, this effect was not modulated by methylphenidate. However, methylphenidate modulated stress effects on activation in paracingulate, orbitofrontal cortex, and anterior cingulate associated with expected value representation in goal-directed behaviour. Conclusion and implications: Our neuroimaging data suggest increased dopamine levels reverse stress-induced changes in brain activation associated with goal-directed behaviour. These effects may be relevant for preventing stress-induced relapse in addictive behaviour.

If phenotypic plasticity is adaptive, then prior exposure to a stressor should reduce effects arising from subsequent stressor exposure. Here, we test the hypothesis that corals exhibit adaptive plasticity to a stressor (vermetid gastropods) mediated by their extended phenotype (coral-associated bacteria). We used a reciprocal transplant experiment to evaluate corals that varied in their prior exposure to vermetid gastropods, a known biotic stressor. We measured a suite of traits associated with coral performance, many of which showed a plastic response to vermetid exposure: decreased calcification, increased microbial diversity, and shifted microbial composition. Most traits (e.g., tissue thickness) also showed a signature of previous exposure environment that persisted after exposure reversal. These phenotypic differences are likely genetic, as reefs with and without vermetids largely comprised of two mitotypes. We suggest cryptic coral variation contributes to different community trajectories, with thin-tissue types more prone to disturbance and subsequent colonization by other species.

Satellite-based solar-induced chlorophyll fluorescence (SIF) has the potential for an early detection and accurate impact assessment of meteorological drought on vegetation photosynthesis. However, how the response of satellite SIF to meteorological drought varies under different climatic conditions and biome types remains poorly understood. In this study, we determined the drought time-scale at which the vegetation photosynthesis response was highest based on the standardized precipitation evapotranspiration index (SPEI) and satellite SIF, and examined how the sensitivity of SIF signals from different ecosystems to drought varied along an aridity gradient in northern China. The results showed that spatial variability of the annual maximum SIF was constrained by wetness conditions and biome types. Annual maximum SIF was positively correlated with SPEI in 57.9% of vegetated lands (P < 0.05). 34.8% of humid ecosystems were characterized by a significant SIF-SPEI correlation (P < 0.05). This percentage reached 44%, 71.4% and 86.2% for arid, sub-humid and semi-arid ecosystems, respectively. The variation of SIF-SPEI correlations was a Gaussian function of the aridity index (AI), with the highest SIF-SPEI correlation appearing in the AI bin of 0.4 (0.37-0.46). The drivers for this pattern were vegetation composition and water availability. The variation of SIF time-scales in response to SPEI was a linear function of the AI, but the slope varied among biomes. To summarize with increasing aridity drought-induced declines in vegetation photosynthesis will be quicker and more significant.