"Space-for-time" substitution is widely used in biodiversity modeling to infer past or future trajectories of ecological systems from contemporary spatial patterns. However, the foundational assumption--that drivers of spatial gradients of species composition also drive temporal changes in diversity--rarely is tested. Here, we empirically test the space-for-time assumption by constructing ortho...

An overview is given of important properties of spatial and temporal intermittency, including evidence of its appearance in fluids, magnetofluids and plasmas, and its implications for understanding of heliospheric plasmas. Spatial intermittency is generally associated with formation of sharp gradients and coherent structures. The basic physics of structure generation is ideal, but when dissipat...

Environmental gradients are instrumental in shaping the distribution and local abundance of species because at the most fundamental level, an organism's performance is constrained by the environment it inhabits. In topographically complex landscapes, slope, aspect, and vegetative cover interact to affect solar exposure, creating temperature-moisture gradients and unique microclimates. The signi...

This issue addresses the present-day budget for anthropogenic CO 2 , and particularly the distribution and controlling factors of net terrestrial sinks for atmospheric CO 2 . The latter are of increasing political and economic importance under international CO2 mitigation agreements. Inverse modelling of meridional and zonal atmospheric, data(e.g. CO 2 , O 2, C), is one way to constrain terrest...

The purpose of this paper is to present the development of a simple turbulence representation suitable for helicopter dynamic simulation, stability and performance analysis, as well as pilot-in-the-loop rotorcraft handling qualities assessment. The frozen field hypothesis and linear approximation are assumed. Components of the uniform field velocity are included as additive perturbations affect...

The study of cellular responses to changes in the spatial distribution of molecules in development, immunology and cancer, requires reliable methods to reproduce in vitro the precise distributions of proteins found in vivo. Here we present a straightforward method for generating substrate-bound protein patterns which has the simplicity required to be implemented in typical life science laborato...

It is well established that bacteria are able to respond to temporal gradients (e.g., by chemotaxis). However, it is widely held that prokaryotes are too small to sense spatial gradients. This contradicts the common observation that the vast majority of bacteria live on the surface of a solid substrate (e.g., as a biofilm). Herein we report direct experimental evidence that the nonmotile bacter...

Successful biological development via spatial and temporal regulations of cell differentiation relies on the action of multiple signaling molecules that are known as morphogens. It is now well established that biological signaling molecules create nonuniform concentration profiles, called morphogen gradients, that activate different genes, leading to patterning in the developing organisms. The ...

The Drosophila blastoderm and the vertebrate neural tube are archetypal examples of morphogen-patterned tissues that create precise spatial patterns of different cell types. In both tissues, pattern formation is dependent on molecular gradients that emanate from opposite poles. Despite distinct evolutionary origins and differences in time scales, cell biology and molecular players, both tissues...

The profound metabolic reprogramming that occurs in cancer cells has been investigated primarily in two-dimensional cell cultures, which fail to recapitulate spatial aspects of cell-to-cell interactions as well as tissue gradients present in three-dimensional tumours. Here, we describe an engineered model to assemble three-dimensional tumours by rolling a scaffold-tumour composite strip. By unr...