Rapid sample preparation for detection of antibiotic resistance on a microfluidic disc platform.

Rapid, point-of-care (PoC) diagnostics for antibiotic susceptibility testing (AST) are critical in combating the antimicrobial resistance epidemic. While new, alternative technologies are capable of rapidly identifying antibiotic resistance, traditional AST methods, where a patient sample is incubated with different antibiotics, remain the most reliable and practical in determining antibiotic effectiveness. Here, we demonstrate a novel sample incubation technique on a microfluidic centrifugal disc (CD) as a proof of concept automated sample processing platform for AST.

Developmental bias in the evolution of phalanges.

Evolutionary theory has long argued that the entrenched rules of development constrain the range of variations in a given form, but few empirical examples are known. Here we provide evidence for a very deeply conserved skeletal module constraining the morphology of the phalanges within a digit. We measured the sizes of phalanges within populations of two bird species and found that successive phalanges within a digit exhibit predictable relative proportions, whether those phalanges are nearly equal in size or exhibit a more striking gradient in size from large to small.

Response to comment on "Evolutionary trade-offs, Pareto optimality, and the geometry of phenotype space".

Edelaar raises concerns about the way we tested our theory. Our mathematical theorem predicts that despite the high dimensionality of trait space, trade-offs between tasks leads to phenotypes in low-dimensional regions in trait space, such as lines and triangles. We address Edelaar's questions with statistical tests that eliminate pseudoreplication concerns, finding that our predictions remain convincingly supported.

The geometry of the Pareto front in biological phenotype space.

When organisms perform a single task, selection leads to phenotypes that maximize performance at that task. When organisms need to perform multiple tasks, a trade-off arises because no phenotype can optimize all tasks. Recent work addressed this question, and assumed that the performance at each task decays with distance in trait space from the best phenotype at that task.

Comparing apples and oranges: fold-change detection of multiple simultaneous inputs.

Sensory systems often detect multiple types of inputs. For example, a receptor in a cell-signaling system often binds multiple kinds of ligands, and sensory neurons can respond to different types of stimuli. How do sensory systems compare these different kinds of signals? Here, we consider this question in a class of sensory systems - including bacterial chemotaxis- which have a property known as fold-change detection: their output dynamics, including amplitude and response time, depends only on the relative changes in signal, rather than absolute changes, over a range of several decades of signal.

Fold-change detection and scalar symmetry of sensory input fields.

Recent studies suggest that certain cellular sensory systems display fold-change detection (FCD): a response whose entire shape, including amplitude and duration, depends only on fold changes in input and not on absolute levels. Thus, a step change in input from, for example, level 1 to 2 gives precisely the same dynamical output as a step from level 2 to 4, because the steps have the same fold change. We ask what the benefit of FCD is and show that FCD is necessary and sufficient for sensory search to be independent of multiplying the input field by a scalar.

The incoherent feedforward loop can provide fold-change detection in gene regulation.

Many sensory systems (e.g., vision and hearing) show a response that is proportional to the fold-change in the stimulus relative to the background, a feature related to Weber's Law.