Food security concerns and the scarcity of new productive land have put productivity enhancement of degraded lands back on the political agenda. In such a context, salt-affected lands are a valuable resource that cannot be neglected nor easily abandoned even with their lower crop yields, especially in areas where significant investments have already been made in irrigation and drainage infrastructure. A review of previous studies shows a very limited number of highly variable estimates of the costs of salt-induced land degradation combined with methodological and contextual differences. Simple extrapolation suggests that the global annual cost of salt-induced land degradation in irrigated areas could be US$ 27.3 billion because of lost crop production. We present selected case studies that highlight the potential for economic and environmental benefits of taking action to remediate salt-affected lands. The findings indicate that it can be cost-effective to invest in sustainable land management in countries confronting salt-induced land degradation. Such investments in effective remediation of salt-affected lands should form part of a broader strategy for food security and be defined in national action plans. This broader strategy is required to ensure the identification and effective removal of barriers to the adoption of sustainable land management, such as perverse subsidies. Whereas reversing salt-induced land degradation would require several years, interim salinity management strategies could provide a pathway for effective remediation and further showcase the importance of reversing land degradation and the rewards of investing in sustainable land management

Amorphous solids yield at a critical value of the strain (in strain controlled experiments); for larger strains the average stress can no longer increase -the system displays an elasto-plastic steady state. A long standing riddle in the materials community is what is the difference between the microscopic states of the material before and after yield. Explanations in the literature are material specific, but the universality of the phenomenon begs a universal answer. We argue here that there is no fundamental difference in the states of matter before and after yield, but the yield is a bona-fide first order phase transition between a highly restricted set of possible configurations residing in a small region of phase space to a vastly rich set of configurations which include many marginally stable ones. To show this we employ an order parameter of universal applicability, independent of the microscopic interactions, that is successful in quantifying the transition in an unambiguous manner.A ubiquitous, and in fact universal, characteristic of the mechanical properties of amorphous solids is their stress vs. strain dependence [1]. Measured in countless quasi-static strain-controlled simulations (see for example [2][3][4][5][6][7][8]) and experiments (see for example [9][10][11]), it typically exhibits two distinct regions. In one region, at lower strain values, the stress σ increases on the average upon the increase of strain γ, although this increase is punctuated by plastic events. A second region, at higher values of the strain, displays a constant (on the average) stress which cannot increase even though the strain keeps increasing. Of course also this elasto-plastic steady state branch is punctuated by plastic events. A typical such shear stress vs. shear strain curve at zero temperature is shown in Fig. 1. The two regions are separated by what is referred to as "yield". The actual shape of the stress vs. strain curve near the yield point depends on details of the system preparation. Amorphous solids prepared by a slow quench from the melt tend to display a stress peak before yielding, whereas those prepared by a fast quench join the steady state smoothly without a stress peak [12]. Of course the steady state branch itself is independent of the preparation protocol; memory of the initial state is lost in this regime.The phenomenon of the mechanical yield in amorphous solids has been a subject of extensive study in recent years. Many numerical studies on the subject have been performed using athermal, quasi-static shear (AQS) protocols, wherein a glass is made by quenching a glass former down to zero temperature, and then subjecting it to a quasi-static (γ → 0) shear protocol wherein the system is subject to small shear steps, and then allowed, after each step, to find a new mechanically stable minimum of its potential energy. This kind of protocol always gives rise to the same basic kind of phenomenology as seen in Fig. 1 independently of the detailed microscopic interaction between the constituents. This ba...

Anomalous behavior of the excess entropy (S(e)) and the associated scaling relationship with diffusivity are compared in liquids with very different underlying interactions but similar water-like anomalies: water (SPC/E and TIP3P models), tetrahedral ionic melts (SiO(2) and BeF(2)), and a fluid with core-softened, two-scale ramp (2SRP) interactions. We demonstrate the presence of an excess entropy anomaly in the two water models. Using length and energy scales appropriate for onset of anomalous behavior, we show the density range of the excess entropy anomaly to be much narrower in water than in ionic melts or the 2SRP fluid. While the reduced diffusivities (D*) conform to the excess-entropy-scaling relation, D* = A exp(alphaS(e)) for all the systems (Rosenfeld, Y. Phys. Rev. A 1977, 15, 2545), the exponential scaling parameter, alpha, shows a small isochore dependence in the case of water. Replacing S(e) by pair correlation-based approximants accentuates the isochore dependence of the diffusivity scaling. Isochores with similar diffusivity-scaling parameters are shown to have the temperature dependence of the corresponding entropic contribution. The relationship between diffusivity, excess entropy, and pair correlation approximants to the excess entropy are very similar in all the tetrahedral liquids.

We present the estimation of heritabilities of an observed trait in situations where evaluation of several pure breeding lines is performed in a trial at a single location and in trials from several locations. For the single location situation, we evaluate exact confidence intervals, the probability of invalid estimates, and the percentage points of the distribution of heritability. Simulations were performed to numerically verify the results. Additionally, approximations to the bias and standard error of the estimate were obtained and are presented along with their simulated values and coefficients of skewness and kurtosis. For trials in several locations, explicit expressions for exact values of confidence limits are not available. Further, one would require knowledge of one more parameter, represented by the ratio of genotype x environment (G x E) interaction variance to error variance, in addition to the number of genotypes, replication and true heritability value. Approximations were made for bias and the standard error of estimates of heritability. The evaluation of the distribution of heritability and its moments was recognized as a problem of the linear function of an independent chi-square. The methods have been illustrated by data from experiments on grain and straw yield of 64 barley genotypes evaluated at three locations.