Universidad del Norte, Colombia

About: Universidad del Norte, Colombia is a education organization based out in Barranquilla, Colombia. It is known for research contribution in the topics: Population & Context (language use). The organization has 3562 authors who have published 4355 publications receiving 37861 citations. The organization is also known as: University of the North, Colombia & Uninorte.

Gall midge attack intensity and host-plant response in a Neotropical coastal ecosystem

Abstract: The gall inducer Clusiamyia nitida Maia, 1996 (Diptera, Cecidomyiidae) often infests the shrub Clusia lanceolata (Camb.) (Clusiaceae) in the Neotropical vegetation of restinga of Rio de Janeiro State, Brazil. Leaves of Clusia lanceolata host up to 20 spheroid galls and show variation in their shape. We aimed to evaluate the effect of gall's intensity on leaves of Clusia lanceolata, and the extension of gall's impact on adjacent non-galled leaves. We analyzed the effect of the number of galls on leaf area, biomass, specific area and leaf appearance from 509 leaves of 14 individual plants. The results showed that differences of individual plants, pairs of leaves, and gall presence were responsible for more then 90% of variation on infested leaves. Variation on parasitic intensity level created differences in leaf response. Under moderate gall attack characterized by scattered galls on a leaf, the increase of the number of galls caused an increase of leaf biomass and area, and a decrease of specific area. The specific area was smaller also under high attack intensity, characterized by coalescent galls on a leaf. In those cases of extremely high parasitic intensity, galled leaves became deformed and the surface area was severely reduced. Leaf deformation due to gall attack led to early leaf abscission, indicated by the 90% of deformed leaves found in the youngest leaf pair of the branch. There was insufficient evidence that the impact of galls on leaf morpho-physiological parameters extended beyond the attacked leaves, because ungalled leaves did not change significantly when their opposite leaf had been galled.

Micromilling research: current trends and future prospects

Abstract: Micro-milling through mechanical chip removal process has attracted much attention among researchers due to its flexibility and productivity that allow an extensive application for manufacturing several types of micro-components for the modern-day world. Its potential is continuously growing as the market demands continuous innovation in the manufacturing of high precision products with progressively smaller dimensions. Its global research and available literature increased very fast in recent years. Relevant topics like size effect, burr formation, surface quality, cutting forces, tool wear, vibrations, and process optimization as highlighted by a systematic bibliometric study during the period 2000–2019 must be properly addressed. The review work on such a scale was not attempted earlier by considering many parameters at a time. Hence, this study may provide a current view and future prospects of mainstream research on micro-milling worldwide.

The First Cathedral on America's Pacific Coast

Abstract: New research dispels the idea that Panama Viejo was initially founded one-half mile from the site of its visible present-day ruins. The archaeological and historical evidence, subjected to interdisciplinary analysis, demonstrates that the city remained on the same main plaza next to its natural port from its founding 500 years ago until its destruction in 1671. The data reconsidered and newly uncovered also suggest reasons for previous misinterpretations of the city’s early foundational history. Unlike many colonial cities and towns, Panama Viejo did not move during its first century of existence. However, its main church, which became the bishopric’s cathedral in 1524, did relocate after 1541. The new evidence establishes and confirms the original location of the first cathedral on America’s Pacific Ocean to the south of Panama Viejo’s main plaza and explains its move to an elevated, rocky area on the eastern side of the same plaza over 20 years later. Excavations undertaken in 2018 have confirmed the original building’s location a mere 50 m from the visible ruins of the cathedral, the tower of which remains a symbol of Panamanian identity today.

Isotope sclerochronology indicates enhanced seasonal precipitation in northern South America (Colombia) during the Mid-Miocene Climatic Optimum

Abstract: During the Mid-Miocene Climatic Optimum (MMCO, 14.7–17.3 Ma), global temperatures were warmer than present, and similar to predicted temperatures for the coming century. Limited paleoclimate data exist from the tropics during this period, despite its potential as an analog for future climate conditions. This study presents new subannual stable isotope data (δ18O and δ13C) from a large population of Miocene Turritella gastropods from the Jimol and Castilletes Formations of the Guajira Peninsula, Colombia. Turritellids are aragonitic marine mollusks that live in shallow coastal waters, and their rapid growth rates allow for high-resolution subannual records. We compare these fossils to modern Turritella gastropods from multiple tropical localities to reconstruct subannual climate conditions. The seasonal range in δ18O in the modern shells correlates with the seasonal variance of local precipitation, once temperature seasonality is accounted for. The Miocene fossils show larger (in some cases >2‰) seasonal variation in δ18O than modern Turritella from the same location, suggesting increased seasonality of precipitation in Miocene northern Colombia relative to today. We propose that this increased seasonality of precipitation was due to a more northerly position of the Intertropical Convergence Zone during the mid-Miocene. The resulting wet Miocene paleoenvironment is in stark contrast to semiarid conditions on the Guajira Peninsula today, indicating that this area of tropical South America has undergone a drastic environmental change since the Miocene.