Variational inference transforms posterior inference into parametric optimization thereby enabling the use of latent variable models where it would otherwise be impractical. However, variational inference can be finicky when different variational parameters control variables that are strongly correlated under the model. Traditional natural gradients that use the variational approximation fail t...

We examine regulation of distribution tariffs in the Mexican natural gas industry. Average revenue in each period is constrained not to exceed an upper bound and is calculated as the ratio of total revenue to output in the current period. This regime implies incentives for setting two-part tariffs strategically. The usage charge is typically dropped to its lowest feasible level while the fixed ...

Recent studies of correlations of intensity in databases of natural images revealed a remarkable property. The two point correlations are described in terms of power law behavior, with an exponent which seems to be robust. In the present Letter we consider the statistical meaning of that result. We study many individual images of one of the databases considered. We find that the same law charac...

A review of the natural history of bats in Tasmania is presented along with data collected in recent surveys. Recent taxonomic changes affecting the Tasmanian bat species are discussed and a key is provided to allow the identification of Tasmanian bats. The appearance of each species is described and body measurements given. Tasmanian popUlations do not show a uniform trend of increased size co...

We present for the first time objectively mapped natural radiocarbon (14C) abundance in the global deep ocean using mostly new measurements from the World Ocean Circulation Experiment (WOCE). Compared to earlier data from the Geochemical Ocean Sections Study, the new data number almost seven times more. Also, the WOCE data collected during the 1990s have sufficient spatial coverage to make obje...

Alkamides are a broad and expanding group of bioactive natural compounds found in at least 33 plant families. Despite the relatively simple molecular architecture of alkamides (fig. 1), these natural products show broad structural variability and an important range of biological activities, such as immunomodulatory, antimicrobial, antiviral, larvicidal, insecticidal, diuretic, pungent, analgesi...