Heuristics for implementation of a hybrid preconditioner for interior-point methods

This article presents improvements to the hybrid preconditioner previously developed for the solution through the conjugate gradient method of the linear systems which arise from interior-point methods. The hybrid preconditioner consists of combining two preconditioners: controlled Cholesky factorization and the splitting preconditioner used in different phases of the optimization process. The first, with controlled fill-in, is more efficient at the initial iterations of the interior-point methods and it may be inefficient near a solution of the linear problem when the system is highly ill-conditioned; the second is specialized for such situation and has the opposite behavior. This approach works better than direct methods for some classes of large-scale problems. This work has proposed new heuristics for the integration of both preconditioners, identifying a new change of phases with computational results superior to the ones previously published. Moreover, the performance of the splitting preconditioner has been improved through new orderings of the constraint matrix columns allowing savings in the preconditioned conjugate gradient method iterations number. Experiments are performed with a set of large-scale problems and both approaches are compared with respect to the number of iterations and running time.57959

Oxygen in the Tropical Pacific POSTRE II First Tracer Survey, Cruise No. M135, March 01 - April 08, 2017, Valparaiso (Chile) - Callao (Peru) POSTRE-III

Cruise M135 was a contribution to the DFG Collaborative Research Project (SFB) 754: “Climate-Biogeochemistry Interactions in the Tropical Ocean” with the main goal to better understand the the role of diffusive and advective pathways connecting water within the bottom boundary layer (i.e. the water directly affected by sediment processes) to the pelagic and surface ocean. To achieve this, we have injected a conservative tracer (CF3SF5) within the bottom boundary layer at three different sites along the Peruvian coast at a depth of about 300 m in October 2015 that was mapped during M135. Tracer sampling was carried out by measuring water samples from the CTD-rosette water bottles. In total 144 CTD casts were carried out. From 132 CTD profiles 2828 samples for CF3CF5 investigations were gained and on most stations the tracer could be found. In addition 48 trace metal CTD’s were recorded and trace metal and chemical samples taken from the rosette bottles. On 166 of the CTD profiles oxygen samples were taken and on 94 CTD profiles nutrient samples were collected. Microstructure measurements were made on 24 stations and 2 gliders were deployed. For geological investigations at 5 locations multicorer and long gravity cores were taken. Continuous underway measurements of CO2,N2O and CO as well as continuous ADCP and thermosalinograph recording was made on 37 days. The cruise M135 was very successful; most systems on METEOR worked well and all planned objectives were reached

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others