This article studies crime rates’ response to economic conditions. Using a longitudinal data set covering about 20 countries over the period 1970-2010, we investigate whether crime rates respond asymmetrically to increases in unemployment and recoveries in economic conditions. We find a positive response of crime rates on variation in unemployment rates, but we do not find compelling evidence o...

In 1988, Seiya Negami published a conjecture stating that a graph G has a finite planar cover (i.e. a homomorphism from some planar graph onto G which maps the vertex neighbourhoods bijectively) if and only if G embeds in the projective plane. Though the ”if” direction is easy, and over ten related research papers have been published during the past 20 years of investigation, this beautiful con...

We studied the effects of hand weeding of second-year plants of the biennial garlic mustard (Alliaria petiolata) on first-year plants (seedlings) and native ground layer vegetation. Garlic mustard is a Eurasian species that has invaded deciduous forest ground layers in eastern North America. Treatments consisted of a control and an early or late weeding of second-year garlic mustard. The early ...

The effects of selected physical and biological factors on the early development of a subtidal invertebrate assemblage were examined at an offshore oil platform in the Santa Barbara Channel (California, USA). The effects of date, year, length, and depth of submersion were investigated by replacing sets of ceramic tiles with new tiles at frequencies of 2, 4, 6, 12, and 24 months at three depths ...

Changes to land use and disturbance frequency threaten disturbance-dependent Lepidoptera within sandplain habitats of the northeastern United States. The frosted elfin (Callophrys irus) is a rare and declining monophagous butterfly that is found in xeric open habitats maintained by disturbance. We surveyed potential habitat for adult frosted elfins at four sites containing frosted elfin populat...

For a Noetherian local domain (R, m, K), it is an open question whether strong F–regularity deforms. We provide an affirmative answer to this question when the canonical module satisfies certain additional assumptions. The techniques used here involve passing to a Gorenstein ring, using an anti– canonical cover.

Various observation- and reanalysis-based estimates of sea ice mass and ocean heat content trends imply that the energy imbalance of the Arctic climate system was similar [1.0 (0.9,1.2) Wm-2] to the global ocean average during the 2000-2015 period. Most of this extra heat warmed the ocean, and a comparatively small fraction went into sea ice melt. Poleward energy transports and radiation contri...