Partisan Gerrymandering and the Construction of American Democracy

Erik J. Engstrom offers a historical perspective on the effects of gerrymandering on elections and party control of the U.S. national legislature. Aside from the requirements that districts be continuous and, after 1842, that each select only one representative, there were few restrictions on congressional districting. Unrestrained, state legislators drew and redrew districts to suit their own partisan agendas. With the rise of the “one-person, one-vote” doctrine and the implementation of the Voting Rights Act of 1965, however, redistricting became subject to court oversight. Engstrom evaluates the abundant cross-sectional and temporal variation in redistricting plans and their electoral results from all the states, from 1789 through the 1960s, to identify the causes and consequences of partisan redistricting. His analysis reveals that districting practices across states and over time systematically affected the competitiveness of congressional elections, shaped the partisan composition of congressional delegations, and, on occasion, determined party control of the House of Representatives

Deep flaws in weldments of aluminum and titanium

Surface flawed specimens of 2219-T87 and 6Al-4V STA titanium weldments were tested to determine static failure modes, failure strength, and fatigue flaw growth characteristics. Thicknesses selected for this study were purposely set at values where, for most test conditions, abrupt instability of the flaw at fracture would not be expected. Static tests for the aluminum weldments were performed at room, LN2 and LH2 temperatures. Titanium static tests for tests were performed at room and LH2 temperatures. Results of the static tests were used to plot curves relating initial flaw size to leakage- or failure-stresses (i.e. "failure" locus curves). Cyclic tests, for both materials, were then performed at room temperature, using initial flaws only slightly below the previously established failure locus for typical proof stress levels. Cyclic testing was performed on pairs of specimens, one with and one without a simulated proof test cycle. Comparisons were made then to determine the value and effect of proof testing as affected by the various variables of proof and operating stress, flaw shape, material thickness, and alloy

Buckling without bending: a new paradigm in morphogenesis

A curious feature of organ and organoid morphogenesis is that in certain cases, spatial oscillations in the thickness of the growing "film" are out-of-phase with the deformation of the slower-growing "substrate," while in other cases, the oscillations are in-phase. The former cannot be explained by elastic bilayer instability, and contradict the notion that there is a universal mechanism by which brains, intestines, teeth, and other organs develop surface wrinkles and folds. Inspired by the microstructure of the embryonic cerebellum, we develop a new model of 2d morphogenesis in which system-spanning elastic fibers endow the organ with a preferred radius, while a separate fiber network resides in the otherwise fluid-like film at the outer edge of the organ and resists thickness gradients thereof. The tendency of the film to uniformly thicken or thin is described via a "growth potential". Several features of cerebellum, +blebbistatin organoid, and retinal fovea morphogenesis, including out-of-phase behavior and a film thickness amplitude that is comparable to the radius amplitude, are readily explained by our simple analytical model, as may be an observed scale-invariance in the number of folds in the cerebellum. We also study a nonlinear variant of the model, propose further biological and bio-inspired applications, and address how our model is and is not unique to the developing nervous system.Comment: version accepted by Physical Review

k-Distinct Lattice Paths

Lattice paths can be used to model scheduling and routing problems, and, therefore, identifying maximum sets of k-distinct paths is of general interest. We extend the work previously done by Gillman et. al. to determine the order of a maximum set of k-distinct lattice paths. In particular, we disprove a conjecture by Gillman that a greedy algorithm gives this maximum order and also refine an upper bound given by Brewer et. al. We illustrate that brute force is an inefficient method to determine the maximum order, as it has time complexity O(nk)

Recruitment responses of benthic infauna to manipulated sediment geochemical properties in natural flows

Recent studies have shown that local variation in surface sediment geochemistry can have significant effects on recruitment rates of benthic invertebrates. Experiments presented here tested (1) the utility of manipulating surface porewater concentrations using spiked polyacrylamide gels and (2) the recruitment responses of the polychaete Arenicola cristata and the bivalve Mercenaria mercenaria to manipulated ammonium concentrations in realistic flows provided by a straight flume and an annular flume. Data show that successful manipulation of sediment porewater ammonium concentration is feasible in flowing waters, i.e., overlying waters remained relatively free of ammonium while manipulated concentration levels were maintained within the upper sediment layers where new recruits explore. Thus, over short experimental periods, ammonium signals can be independently modified while variables such as grain size, organic content and flow are held constant. Responses of new recruits varied as a function of experimental condition. In straight flume trials, the manipulation of ammonium concentration was successful, and within the range of concentrations tested, retention of Mercenaria was significantly reduced at the highest ammonium level. However, retention of Arenicola was uniformly low among all treatments and no significant ammonium response was detected. In annular flume runs, overall ammonium concentrations were higher than in straight flume runs, but were consistent with the intended manipulation. Mercenaria retention was uniformly low, and no differences in retention, as a function of ammonium concentration, were found. However, for Arenicola, significant differences were observed, with highest retention in lower ammonium environments. These results suggest that ammonium, isolated from other cues, plays a significant role in determining recruitment patterns, with variation in recruit responses related to signal strength

Building a Movement: Community Development and Community Resilience in Response to Extreme Events

There are gaps in understanding what community resilience is and means to those working in communities, academia, practice and policy and how it is currently enacted in Scotland. Greater understanding of existing experiences can be used to encourage development of community resilience. By enhancing resilience, those affected by extreme events are better able to cope; communities are given a voice; and risk and vulnerability on local, national and global scales are reduced.Document also available on the Project web site at: https://extremeevents.stir.ac.uk/files/2020/01/CR2EE-Policy-Brief-Jan-2020.pd

Die Jugendgerichtshilfe in Berlin, 1905–1914. Intersektionale Expertise im Umgang mit jugendlicher Devianz

Im Folgenden werden bestimmte lokale Strategien und Praktiken am Beispiel Berlins untersucht, die in sozialen und kulturellen Nischen jenseits der großen und gut erforschten Strafrechtsreformdebatten Anwendung fanden. Dieser Perspektivenwechsel ist besonders relevant, da die Jugendgerichte und die damit verbundene Jugendgerichtsbewegung dezidiert aus solchen Nischen „praeter legem“ – also neben dem Gesetz – hervorgegangen waren (Simon 1915, 244). Und im Gegensatz zur heftig umkämpften und vorerst ergebnislos verlaufenden Strafrechtsreform, wurde die Jugendgerichtsbewegung allgemein nicht nur als durchschlagender Erfolg, sondern auch, wie der Reformjurist Franz von Liszt es ausdrückte, als „von einer breiten volkstümlichen, nicht bloß von einer literarisch-juristischen Bewegung getragen“ gefeiert (v. Liszt 1909, 140). (DIPF/Orig.

Individual Differences in Coping with Large Multimodal Conflicts in a Spatial Orientation Paradigm

This study examined how humans respond to large 180º disparities between internally generated self-motion cues and external landmarks in a navigation task. Subjects learned the locations of 4 objects in a virtual environment, navigating back to these sites in a testing phase that probed their sense of direction at dead-ends. In select (incongruent) trials, subjects’ virtual rotations were mirrored relative to their physical turns, forcing them to navigate along separate virtual and physical trajectories. On these trials, subjects were either instructed to navigate using their memory of the required turn sequence (proprioceptive instructions) or the external environment (visual instructions). Subjects fell into two categories based on whether they required clarification about how they should be orienting at endpoints in incongruent trials. The clarification group achieved higher accuracy under congruent conditions and appeared to prefer the visual modality in incongruent trials. This group performed similarly regardless of pathway geometry, and was more prone to modality discounting. The other group yielded higher errors in congruent conditions, performed differentially depending on pathway geometry, tended to place more weight on the proprioceptive modality, and was prone to modality averaging. Both groups modulated their modality weighting based on navigation instructions. This study supports the position that human individuals employ different strategies when navigating under cue conflict conditions. It demonstrates that individuals who rely on visual landmarks commit smaller errors (and are less sensitive to trajectory shape) than individuals who rely on internal self-motion feedback when orienting, who also demonstrated greater propensity for cue averaging. These findings suggest that there may be individual differences in the internal representation of space, including how it is accessed and encoded online