Timed Commitments Revisited

Timed commitments (Boneh and Naor, CRYPTO 2000) are a variant of standard commitments which incorporates a forced opening mechanism that allows anyone to reveal the committed message, but not before a certain prescribed date. Timed commitments have a wide-range of applications such as contract signing, fair multi-party computation, sealed bid auctions or new blockchain applications such as preventing front-running or unbiased randomness generation. We revisit the notion of timed commitments and propose an alternative simplified definition. We also provide two new constructions of timed commitments with different trade-offs

aPlonK : Aggregated PlonK from Multi-Polynomial Commitment Schemes

PlonK is a prominent universal and updatable zk-SNARK for general circuit satisfiability. We present aPlonK, a variant of PlonK that reduces the proof size and verification time when multiple statements are proven in a batch. Both the aggregated proof size and the verification complexity of aPlonK are logarithmic in the number of aggregated statements. Our main building block, inspired by the techniques developed in SnarkPack (Gailly, Maller, Nitulescu, FC 2022), is a multi-polynomial commitment scheme, a new primitive that generalizes polynomial commitment schemes. Our techniques also include a mechanism for involving committed data into PlonK statements very efficiently, which can be of independent interest. We also implement an open-source industrial-grade library for zero-knowledge PlonK proofs with support for aPlonK. Our experimental results show that our techniques are suitable for real-world applications (such as blockchain rollups), achieving significant performance improvements in proof size and verification time

Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹

WagnerClimateSeasonalityLimitsSupplementalTablesandFigures.pdf

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹

WagnerClimateSeasonalityLimits.pdf

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹