How did the location of industry respond to falling transport costs in Britain before World War I?

This article explores the location of industry in pre–World War I Britain using a model that takes account both of factor endowment and also of New Economic Geography influences. Broadly speaking, the pattern of industrial location in this period was quite persistent and regional specialization changed little. The econometric results show that factor endowments had much stronger effects than proximity to markets, although the latter was an attraction for industries with large plant size. Overall, falling transport costs had relatively little effect on industrial location at a time when proximity to natural resources, notably coal, mattered most

Orientability thresholds for random hypergraphs

Let $h>w>0$ be two fixed integers. Let \orH be a random hypergraph whose hyperedges are all of cardinality $h$. To {\em $w$-orient} a hyperedge, we assign exactly $w$ of its vertices positive signs with respect to the hyperedge, and the rest negative. A $(w,k)$-orientation of \orH consists of a $w$-orientation of all hyperedges of \orH, such that each vertex receives at most $k$ positive signs from its incident hyperedges. When $k$ is large enough, we determine the threshold of the existence of a $(w,k)$-orientation of a random hypergraph. The $(w,k)$-orientation of hypergraphs is strongly related to a general version of the off-line load balancing problem. The graph case, when $h=2$ and $w=1$, was solved recently by Cain, Sanders and Wormald and independently by Fernholz and Ramachandran, which settled a conjecture of Karp and Saks.Comment: 47 pages, 1 figures, the journal version of [16

Feedback through graph motifs relates structure and function in complex networks

In physics, biology and engineering, network systems abound. How does the connectivity of a network system combine with the behavior of its individual components to determine its collective function? We approach this question for networks with linear time-invariant dynamics by relating internal network feedbacks to the statistical prevalence of connectivity motifs, a set of surprisingly simple and local statistics of connectivity. This results in a reduced order model of the network input-output dynamics in terms of motifs structures. As an example, the new formulation dramatically simplifies the classic Erdos-Renyi graph, reducing the overall network behavior to one proportional feedback wrapped around the dynamics of a single node. For general networks, higher-order motifs systematically provide further layers and types of feedback to regulate the network response. Thus, the local connectivity shapes temporal and spectral processing by the network as a whole, and we show how this enables robust, yet tunable, functionality such as extending the time constant with which networks remember past signals. The theory also extends to networks composed from heterogeneous nodes with distinct dynamics and connectivity, and patterned input to (and readout from) subsets of nodes. These statistical descriptions provide a powerful theoretical framework to understand the functionality of real-world network systems, as we illustrate with examples including the mouse brain connectome.Comment: 31 pages, 20 figure

Histotripsy Homogenization of the Prostate: Thresholds for Cavitation Damage of Periprostatic Structures

Background and Purpose: Histotripsy is a noninvasive, pulsed ultrasound technology that produces mechanically homogenized tissue within targeted volumes. Previous work has demonstrated prostatic tissue debulking in a canine model. The aim was to establish safety thresholds by evaluating histologic changes of urinary sphincter, neurovascular bundle (NVB), and rectum after targeted histotripsy treatment of these critical structures. Materials and Methods: Rectum, urinary sphincter, and NVB in five anesthetized canines were targeted for histotripsy treatment (50 total points). Locations received 1k, 10k, or 100k acoustic pulses (4 microsecond, 1-MHz) at a repetition frequency of 500-Hz. Canine subjects were euthanized immediately (2), survived 3 days (1), or 2 weeks (3) after treatment. Prostates, periprostatic tissue, and rectum were harvested and processed for histology. Results: The sphincter was structurally intact with minimal muscle fiber disruption even after 100k pulses (n=10). Undamaged nerves, arteries, and veins of the NVB were seen despite mechanical homogenization of surrounding loose connective tissue (n=19). The rectum, however, exhibited dose-dependent damage (n=20). 1k pulses yielded mild submucosal hemorrhage. 10k pulses resulted in moderate collagen disruption and focal mucosal homogenization. 100k pulses produced damage to the mucosa and muscularis propria with extensive hemorrhage and collagen disruption. One canine treated with 100k pulses needed early euthanasia (day 3) because of complications from a urine leak. Conclusions: Histotripsy histologic tissue effect varied based on targeted structure with substantial structural preservation of NVB and sphincter. Rectal subclinical damage was apparent after 1k pulses and increased in extent and severity with escalating doses. Future work will include assessment of functional outcomes and refinement of these initial safety thresholds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90446/1/end-2E2010-2E0648.pd

A Different Path: The Global Water Crisis and Rainwater Harvesting

The global water crisis is predicted to kill 34 to 76 million people by 2020. Large-scale infrastructure projects can provide water, but construction of these projects has not proven adequate to meet growing populations and, even where feasible, large-scale projects have significant social, economic and environmental impacts. A different path to solving the global water crisis that emphasizes efficiency and sustainable, community-scale projects in addition to centralized infrastructure, has been mapped by a range of scholars and activists. Small scale rainwater harvesting is one sustainable approach that is proving increasingly effective in both rural and urban settings in the developing world.This paper surveys the use of rainwater harvesting in India and draws some lessons for the application of this approach to other regions

Statistical Photocalibration of Photodetectors for Radiometry without Calibrated Light Sources

Calibration of CCD arrays for identifying bad pixels and achieving nonuniformity correction is commonly accomplished using dark frames. This kind of calibration technique does not achieve radiometric calibration of the array since only the relative response of the detectors is computed. For this, a second calibration is sometimes utilized by looking at sources with known radiances. This process can be used to calibrate photodetectors as long as a calibration source is available and is well-characterized. A previous attempt at creating a procedure for calibrating a photodetector using the underlying Poisson nature of the photodetection required calculations of the skewness of the photodetector measurements. Reliance on the third moment of measurement meant that thousands of samples would be required in some cases to compute that moment. A photocalibration procedure is defined that requires only first and second moments of the measurements. The technique is applied to image data containing a known light source so that the accuracy of the technique can be surmised. It is shown that the algorithm can achieve accuracy of nearly 2.7% of the predicted number of photons using only 100 frames of image data