As mathematical computing becomes more democratized in high-level languages, high-performance symbolic-numeric systems are necessary for domain scientists and engineers to get the best performance out of their machine without deep knowledge of code optimization. Naturally, users need different term types either to have different algebraic properties for them, or to use efficient data structures. To this end, we developed Symbolics.jl, an extendable symbolic system which uses dynamic multiple dispatch to change behavior depending on the domain needs. In this work we detail an underlying abstract term interface which allows for speed without sacrificing generality. We show that by formalizing a generic API on actions independent of implementation, we can retroactively add optimized data structures to our system without changing the pre-existing term rewriters. We showcase how this can be used to optimize term construction and give a 113x acceleration on general symbolic transformations. Further, we show that such a generic API allows for complementary term-rewriting implementations. Exploiting this feature, we demonstrate the ability to swap between classical term-rewriting simplifiers and e-graphbased term-rewriting simplifiers. We illustrate how this symbolic system improves numerical computing tasks by showcasing an e-graph ruleset which minimizes the number of CPU cycles during expression evaluation, and demonstrate how it simplifies a real-world reaction-network simulation to halve the runtime. Additionally, we show a reaction-diffusion partial differential equation solver which is able to be automatically converted into symbolic expressions via multiple dispatch tracing, which is subsequently accelerated and parallelized to give a 157x simulation speedup. Together, this presents Symbolics.jl as a next-generation symbolic-numeric computing environment geared towards modeling and simulation.

Understanding how marine taxa will respond to near-future climate changes is one of the main challenges for management of coastal ecosystem services. Ecological studies that investigate relationships between the environment and shell properties of commercially important marine species are commonly restricted to latitudinal gradients or small-scale laboratory experiments. This paper aimed to explore the variations in shell features and growth of the edible bivalve Chamelea gallina from the Holocene sedimentary succession to present-day thanatocoenosis of the Po Plain-Adriatic Sea system (Italy). Comparing the Holocene sub-fossil record to modern thanatocoenoses allowed obtaining an insight of shell variations dynamics on a millennial temporal scale. Five shoreface-related assemblages rich in C. gallina were considered: two from the Middle Holocene, when regional sea surface temperatures were higher than today, representing a possible analogue for the near-future global warming, one from the Late Holocene and two from the present-day. We investigated shell biometry and skeletal properties in relation to the valve length of C. gallina. Juveniles were found to be more porous than adults in all horizons. This suggested that C. gallina promoted an accelerated shell accretion with a higher porosity and lower density at the expense of mechanically fragile shells. A positive correlation between sea surface temperature and both micro-density and bulk density were found, with modern specimens being less dense, likely due to lower aragonite saturation state at lower temperature, which could ultimately increase the energetic costs of shell formation. Since no variation was observed in shell CaCO3 polymorphism (100% aragonite) or in compositional parameters among the analyzed horizons, the observed dynamics in skeletal parameters are likely not driven by a diagenetic recrystallization of the shell mineral phase. This study contributes to understand the response of C. gallina to climate-driven environmental shifts and offers insights for assessing anthropogenic impacts on this economic relevant species.

Preserving adaptive capacities of coastal ecosystems in the Anthropocene requires an understanding of their natural variability prior to modern times. We quantified responses of nearshore molluscs assemblages to past environmental changes using 101 samples (∼57300 specimens) retrieved from the subsurface Holocene succession and present-day seabed of the Po-Adriatic System (Italy). Present-day assemblages shifted in their faunal composition with respect to their mid-late Holocene counterparts. Major differences are observed in lower nearshore settings, where present-day samples show higher heterogeneity, reduced standardised richness, reduced relative abundance of Lentidium mediterraneum , and increased relative abundance of Varicorbula gibba , scavengers (genus Tritia ), and deposit feeders (nuculid bivalves). A dominance of infaunal opportunistic species and shifts towards detritus-feeding and scavenging are often associated with disturbed benthic habitats. Our results suggest that the ongoing anthropogenic stressors (mainly bottom trawling and non-native species) are currently shifting benthic communities into novel states outside the range of natural variability archived in the fossil record. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6351348

Applied equality saturation in the presence of metaprogramming and multiple dispatch: generic and high-level expression rewriting and analysis in the Julia programming language.

<p>The Mediterranean striped venus (<em>Chamelea gallina</em>) is a valuable economic species in the Mediterranean Sea. In the last decades the over-exploitation of this fishing resource and the occurrence of several mass mortality events, lead to a strong quantitative decline in clam population density in the Adriatic Sea. Studying the effects of climate-driven changes of environmental factors on <em>C. gallina</em>, therefore, is of increasing interest both from an academic and economic point of view.</p><p>Previous studies have mainly focused on population dynamics, shell growth and structure of this species in the present-day Mediterranean Sea. In contrast, there is no information about shell variations in relation to climate-driven environmental change along temporal gradients.</p><p>This ongoing study investigates and contrasts variations in shell microstructure and shell growth parameters of <em>C. gallina</em> assemblages from Holocene sedimentary archives of the Northern Adriatic (Italy). Four shoreface-related <em>C. gallina</em> horizons are being evaluated: two from the present-day Adriatic setting and two from the Middle Holocene sedimentary succession of the Adriatic-Po system, when regional sea surface temperatures were higher than today, thus representing a possible analogue for the near-future global warming. Specifically we aim to: 1) determine the life span of selected specimen using three independent ageing methods (shell surface growth rings, shell internal bands and stable isotope composition); 2) determine shell growth parameters and functions concerning linear extension and net calcification rates for each assemblage investigated.</p><p>This approach should give access to an archive of ecological responses to past climate transitions and enabling reconstruction of the <em>C. gallina</em> natural range of variability on time-scale well beyond the ecological monitoring or small-scale experiments. Additionally, the young (sub)fossil record should offer insights on the adaptive capacities of <em>C. gallina</em> facing near-future anthropogenic warming and may allow implementation of a more effective management of this economically important bivalve species in the near-future.</p>