Quantifying the benefit of a proteome reserve in fluctuating environments.

The overexpression of proteins is a major burden for fast-growing bacteria. Paradoxically, recent characterization of the proteome of Escherichia coli found many proteins expressed in excess of what appears to be optimal for exponential growth. Here, we quantitatively investigate the possibility that this overexpression constitutes a strategic reserve kept by starving cells to quickly meet demand upon sudden improvement in growth conditions. For cells exposed to repeated famine-and-feast cycles, we derive a simple relation between the duration of feast and the allocation of the ribosomal protein reserve to maximize the overall gain in biomass during the feast

Vertex-Unfoldings of Simplicial Polyhedra

We present two algorithms for unfolding the surface of any polyhedron, all of whose faces are triangles, to a nonoverlapping, connected planar layout. The surface is cut only along polyhedron edges. The layout is connected, but it may have a disconnected interior: the triangles are connected at vertices, but not necessarily joined along edges.Comment: 10 pages; 7 figures; 8 reference

Squarepants in a Tree: Sum of Subtree Clustering and Hyperbolic Pants Decomposition

We provide efficient constant factor approximation algorithms for the problems of finding a hierarchical clustering of a point set in any metric space, minimizing the sum of minimimum spanning tree lengths within each cluster, and in the hyperbolic or Euclidean planes, minimizing the sum of cluster perimeters. Our algorithms for the hyperbolic and Euclidean planes can also be used to provide a pants decomposition, that is, a set of disjoint simple closed curves partitioning the plane minus the input points into subsets with exactly three boundary components, with approximately minimum total length. In the Euclidean case, these curves are squares; in the hyperbolic case, they combine our Euclidean square pants decomposition with our tree clustering method for general metric spaces.Comment: 22 pages, 14 figures. This version replaces the proof of what is now Lemma 5.2, as the previous proof was erroneou

Knowledge, Skills, and Abilities in the Precision Agriculture Workforce: An Industry Survey

Precision agriculture encompasses a set of related technologies aimed at better utilizing crop inputs, increasing yield and quality, reducing production risks, and enabling information flow throughout the crop supply and end-use chains. As agricultural businesses invest in precision offerings, their capacity to provide these products and services will depend on their ability to hire and retain employees with appropriate proficiency as defined in their knowledge, skills, and abilities (KSAs). A 2015 survey of agricultural retailers examined the minimum educational requirements retailers were seeking in their hires, along with the importance of a list of KSAs for the various positions that they customarily fill. The positions included equipment operators, sales specialists, technical support, and agronomists. The KSAs included specifics, such as the ability to install, calibrate, troubleshoot, and repair equipment; knowledge of precision agriculture software; and also more broad skills such as effective written and verbal communication and in making agronomy recommendations. As expected, retailers expressed different educational minimums and different levels of importance for various positions. Overwhelmingly, the retailers indicated difficulty in finding qualified candidates and a predominance of candidates with low or deficient proficiency in areas they rated important. The survey was accomplished using email lists from both CropLife and the Certified Crop Adviser program

Is the Custom Service Industry\u27s Role in Precision Agriculture Linked to Workforce Development?

Retail dealership survey data suggests that the lack of a qualified precision agriculture (PA) workforce limits the ability of the PA service industry to provide technological knowledge and services to producers who have adopted PA technology. The key empirical findings suggest that retail dealerships have the greatest difficulty finding workers who have, a) the capability to operate and collect data using specialized PA technology, b) the capability to interpret and develop management strategies using PA generated data, and c) a basic generalized competency in PA technology and its applications. The perceived shortage of skilled workers suggests that there is a need to expand the PA workforce with individuals who have knowledge, skills, and abilities (KSAs). A PA qualified workforce is necessary to provide support for the provision of PA services to current users of PA technology and new PA adopters

The Custom Service Industry\u27s Role in Precision Agriculture Adoption: A Literature Review

This literature review focuses on the role of the precision agriculture (PA) custom services industry in facilitating farmer adoption of PA technology. Based on the review, a series of stylized facts are developed that characterize the custom services industry\u27s role in the PA adoption process in the United States. The literature suggests that increasing the availability of custom services in local agricultural production markets will positively influence the rate of PA adoption. Recent PA custom services industry field surveys, however, indicate that skilled labor, proficient in PA technology, is critical to develop and provide custom services needed to increase the supply of PA services to farmers. These surveys suggest that currently there is a shortage of qualified labor to work in the PA custom services sector. The PA labor issue appears to pose a potential barrier to the provision of PA technical training desired by customers, and the deployment of PA custom services to customers who have adopted or are considering the adoption of PA technology

Orbiter Entry Aeroheating Working Group Viscous CFD Boundary Layer Transition Trailblazer Solutions

Boundary layer transition correlations for the Shuttle Orbiter have been previously developed utilizing a two-layer boundary layer prediction technique. The particular two-layer technique that was used is limited to Mach numbers less than 20. To allow assessments at Mach numbers greater than 20, it is proposed to use viscous CFD to the predict boundary layer properties. This report addresses if the existing Orbiter entry aeroheating viscous CFD solutions, which were originally intended to be used for heat transfer rate predictions, adequately resolve boundary layer edge properties and if the existing two-layer results could be leveraged to reduce the number of needed CFD solutions. The boundary layer edge parameters from viscous CFD solutions are extracted along the wind side centerline of the Space Shuttle Orbiter at reentry conditions, and are compared with results from the two-layer boundary layer prediction technique. The differences between the viscous CFD and two-layer prediction techniques vary between Mach 6 and 18 flight conditions and Mach 6 wind tunnel conditions, and there is not a straightforward scaling between the viscous CFD and two-layer values. Therefore: it is not possible to leverage the existing two-layer Orbiter flight boundary layer data set as a substitute for a viscous CFD data set; but viscous CFD solutions at the current grid resolution are sufficient to produce a boundary layer data set suitable for applying edge-based boundary layer transition correlations

Spurious phase in a model for traffic on a bridge

We present high-precision Monte Carlo data for the phase diagram of a two-species driven diffusive system, reminiscent of traffic across a narrow bridge. Earlier studies reported two phases with broken symmetry; the existence of one of these has been the subject of some debate. We show that the disputed phase disappears for sufficiently large systems and/or sufficiently low bulk mobility.Comment: 8 pages, 3 figures, JPA styl

Optofluidic microscope and its applications in biology

In this article, we will demonstrate a novel optical imaging device that can be directly integrated into a microfluidic network, and therefore enables on-chip imaging in a microfluidic system. This micro imaging device, termed optofluidic microscope (OFM) is potentially free of bulk optics and is based on a nanohole array defined in a nontransmissive metallic layer that is patterned onto the floor of the microfluidic channel. The operation of the optofluidic microscope will be explained in details and its performance is examined by using a popular animal model, Caenorhabditis elegans (C. elegans). Images from a large population of nematode worms are efficiently acquired within a short time frame. The quality of the OFM images of C. elegans and the morphological characteristics revealed therein are evaluated. Two groups of early-stage C elegans larvae, wild-type and dpy-24 are successfully separated even though their morphological difference at the larval stage is subtle. The experimental results support our claim that the methodology described therein can be effectively used to develop a powerful tool for fulfilling high-resolution, high-throughput imaging task in microfluidics-based systems

Nano-Aperture Array Based Optical Imaging System on a Microfluidic Chip

We report the implementation of a novel nano-aperture array based imaging technique in a microfluidic network, termed "Optofluidic Microscopy (OFM)". The OFM prototype features high resolution, compact volume and capable of high-throughput sample imaging