Asymmetric root distributions reveal press–pulse responses in retreating coastal forests

The impacts of climate change on ecosystems are manifested in how organisms respond to episodic and continuous stressors. The conversion of coastal forests to salt marshes represents a prominent example of ecosystem state change, driven by the continuous stress of sea-level rise (press), and episodic storms (pulse). Here, we measured the rooting dimension and fall direction of 143 windthrown eastern red cedar (Juniperus virginiana) trees in a rapidly retreating coastal forest in Chesapeake Bay (USA). We found that tree roots were distributed asymmetrically away from the leading edge of soil salinization and towards freshwater sources. The length, number, and circumference of roots were consistently higher in the upslope direction than downslope direction, suggesting an active morphological adaptation to sea-level rise and salinity stress. Windthrown trees consistently fell in the upslope direction regardless of aspect and prevailing wind direction, suggesting that asymmetric rooting destabilized standing trees, and reduced their ability to withstand high winds. Together, these observations help explain curious observations of coastal forest resilience, and highlight an interesting nonadditive response to climate change, where adaptation to press stressors increases vulnerability to pulse stressors

An Efficient Framework for Global Non-Convex Polynomial Optimization over the Hypercube

We present a novel efficient theoretical and numerical framework for solving global non-convex polynomial optimization problems. We analytically demonstrate that such problems can be efficiently reformulated using a non-linear objective over a convex set; further, these reformulated problems possess no spurious local minima (i.e., every local minimum is a global minimum). We introduce an algorithm for solving these resulting problems using the augmented Lagrangian and the method of Burer and Monteiro. We show through numerical experiments that polynomial scaling in dimension and degree is achievable for computing the optimal value and location of previously intractable global polynomial optimization problems in high dimension

An experimental study of the sensitivity of helicopter rotor blade tracking to root pitch adjustment in hover

The sensitivity of blade tracking in hover to variations in root pitch was examined for two rotor configurations. Tests were conducted using a four bladed articulated rotor mounted on the NASA-Army aeroelastic rotor experimental system (ARES). Two rotor configurations were tested: one consisting of a blade set with flexible fiberglass spars and one with stiffer (by a factor of five in flapwise and torsional stiffnesses) aluminum spars. Both blade sets were identical in planform and airfoil distribution and were untwisted. The two configurations were ballasted to the same Lock number so that a direct comparison of the tracking sensitivity to a gross change in blade stiffness could be made. Experimental results show no large differences between the two sets of blades in the sensitivity of the blade tracking to root pitch adjustments. However, a measurable reduction in intrack coning of the fiberglass spar blades with respect to the aluminum blades is noted at higher rotor thrust conditions

The dynamic bowser routing problem

We investigate opportunities offered by telematics and analytics to enable better informed, and more integrated, collaborative management decisions on construction sites. We focus on efficient refuelling of assets across construction sites. More specifically, we develop decision support models that, by leveraging data supplied by different assets, schedule refuelling operations by minimising the distance travelled by the bowser truck as well as fuel shortages. Motivated by a practical case study elicited in the context of a project we recently conducted at Crossrail, we introduce the Dynamic Bowser Routing Problem. In this problem the decision maker aims to dynamically refuel, by dispatching a bowser truck, a set of assets which consume fuel and whose location changes over time; the goal is to ensure that assets do not run out of fuel and that the bowser covers the minimum possible distance. We investigate deterministic and stochastic variants of this problem and introduce effective and scalable mathematical programming models to tackle these cases. We demonstrate the effectiveness of our approaches in the context of an extensive computational study designed around data collected on site as well as supplied by our project partners. Keywords: Routing; Dynamic Bowser Routing Problem; Stochastic Bowser Routing Problem; Mixed-Integer Linear Programming; Construction

Unsupervised deep learning identifies semantic disentanglement in single inferotemporal neurons

Deep supervised neural networks trained to classify objects have emerged as popular models of computation in the primate ventral stream. These models represent information with a high-dimensional distributed population code, implying that inferotemporal (IT) responses are also too complex to interpret at the single-neuron level. We challenge this view by modelling neural responses to faces in the macaque IT with a deep unsupervised generative model, beta-VAE. Unlike deep classifiers, beta-VAE "disentangles" sensory data into interpretable latent factors, such as gender or hair length. We found a remarkable correspondence between the generative factors discovered by the model and those coded by single IT neurons. Moreover, we were able to reconstruct face images using the signals from just a handful of cells. This suggests that the ventral visual stream may be optimising the disentangling objective, producing a neural code that is low-dimensional and semantically interpretable at the single-unit level

Gender Differences in Compensation, Job Satisfaction and Other Practice Patterns in Urology

The proportion of women in urology has increased from <0.5% in 1981 to 10% today. Furthermore, 33% of students matching in urology are now female. This analysis sought to characterize the female workforce in urology in comparison to men with regard to income, workload, and job satisfaction

Correction: Mutations in LRRK2 linked to Parkinson disease sequester Rab8a to damaged lysosomes and regulate transferrin-mediated iron uptake in microglia

[This corrects the article DOI: 10.1371/journal.pbio.3001480.]

Genomic and Genic Deletions of the FOX Gene Cluster on 16q24.1 and Inactivating Mutations of FOXF1 Cause Alveolar Capillary Dysplasia and Other Malformations

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare, neonatally lethal developmental disorder of the lung with defining histologic abnormalities typically associated with multiple congenital anomalies (MCA). Using array CGH analysis, we have identified six overlapping microdeletions encompassing the FOX transcription factor gene cluster in chromosome 16q24.1q24.2 in patients with ACD/MPV and MCA. Subsequently, we have identified four different heterozygous mutations (frameshift, nonsense, and no-stop) in the candidate FOXF1 gene in unrelated patients with sporadic ACD/MPV and MCA. Custom-designed, high-resolution microarray analysis of additional ACD/MPV samples revealed one microdeletion harboring FOXF1 and two distinct microdeletions upstream of FOXF1, implicating a position effect. DNA sequence analysis revealed that in six of nine deletions, both breakpoints occurred in the portions of Alu elements showing eight to 43 base pairs of perfect microhomology, suggesting replication error Microhomology-Mediated Break-Induced Replication (MMBIR)/Fork Stalling and Template Switching (FoSTeS) as a mechanism of their formation. In contrast to the association of point mutations in FOXF1 with bowel malrotation, microdeletions of FOXF1 were associated with hypoplastic left heart syndrome and gastrointestinal atresias, probably due to haploinsufficiency for the neighboring FOXC2 and FOXL1 genes. These differences reveal the phenotypic consequences of gene alterations in cis

Dysfunction in the βII Spectrin-Dependent Cytoskeleton Underlies Human Arrhythmia.

Background: The cardiac cytoskeleton plays key roles in maintaining myocyte structural integrity in health and disease. In fact, human mutations in cardiac cytoskeletal elements are tightly linked with cardiac pathologies including myopathies, aortopathies, and dystrophies. Conversely, the link between cytoskeletal protein dysfunction in cardiac electrical activity is not well understood, and often overlooked in the cardiac arrhythmia field. Methods and Results: Here, we uncover a new mechanism for the regulation of cardiac membrane excitability. We report that βII spectrin, an actin-associated molecule, is essential for the post-translational targeting and localization of critical membrane proteins in heart. βII spectrin recruits ankyrin-B to the cardiac dyad, and a novel human mutation in the ankyrin-B gene disrupts the ankyrin-B/βII spectrin interaction leading to severe human arrhythmia phenotypes. Mice lacking cardiac βII spectrin display lethal arrhythmias, aberrant electrical and calcium handling phenotypes, and abnormal expression/localization of cardiac membrane proteins. Mechanistically, βII spectrin regulates the localization of cytoskeletal and plasma membrane/sarcoplasmic reticulum protein complexes that include the Na/Ca exchanger, RyR2, ankyrin-B, actin, and αII spectrin. Finally, we observe accelerated heart failure phenotypes in βII spectrin-deficient mice. Conclusions: Our findings identify βII spectrin as critical for normal myocyte electrical activity, link this molecule to human disease, and provide new insight into the mechanisms underlying cardiac myocyte biology