23 research outputs found
Butterflies (Lepidoptera: Papilionoidea and Hesperioidea) of the Parque Ecológico João Vasconcelos Sobrinho, Caruaru, Pernambuco, Brazil
Scalar field "mini--MACHOs": a new explanation for galactic dark matter
We examine the possibility that galactic halos are collisionless ensembles of
scalar field ``massive compact halo objects'' (MACHOs). Using mass constraints
from MACHO microlensing and from theoretical arguments on halos made up of
massive black holes, as well as demanding also that scalar MACHO ensambles of
all scales do not exhibit gravothermal instability (as required by consistency
with observations of LSB galaxies), we obtain the range: m\alt 10^{-7}
M_\odot or 30 M_\odot\alt m\alt 100 M_\odot. The rather narrow mass range of
large MACHOs seems to indicate that the ensambles we are suggesting should be
probably made up of scalar MACHOs in the low mass range (``mini--MACHOs''). The
proposed model allows one to consider a non--baryonic and non--thermal
fundamental nature of dark matter, while at the same time keeping the same
phenomenology of the CDM paradigm.Comment: 5 pages, 1 eps figure. RevTex 4 style. To appear in Physical Review
An illustrated key to male Actinote from Southeastern Brazil (Lepidoptera, Nymphalidae)
Agreement of four analytical methods applied to pb in soils from the small city of st. John’s, NewFoundland, Canada
In the small city of St. John’s, NL (2020 population ~114,000), 100% of the soils of the pre-1926 properties exceeded the Canadian soil Pb standard, 140 mg/kg. The Pb was traced to high-Pb coal ash used for heating and disposed on the soils outside. Analytical instruments became available in the late 1960s and 1970s and were first used for blood Pb and clinical studies and repurposed for measuring environmental Pb. The environmental research part of this study compared four common soil Pb analysis methods on the same set (N = 96) of St. John’s soil samples. The methods: The US EPA method 3050B, portable X-ray fluorescence spectrometry (pXRF), The Chaney–Mielke leachate extraction (1 M nitric acid), and the relative bioaccessibility leaching procedure (US EPA method 1340). Correlation is not the same as agreement. There is strong agreement (Berry–Mielke’s Universal R) among the four soil Pb analytical methods. Accordingly, precaution is normally advisable to protect children from the high-Pb garden soils and play areas. A public health reality check by Health Canada surveillance of St. John’s children (N = 257) noted remarkably low blood Pb. The low blood Pb of St. John’s’ children is contrary to the soil Pb results. Known urban processes causing the rise of environmental Pb and children’s Pb exposure includes particle size, aerosol emission by traffic congestion, and quantities of leaded petrol during the 20th century. Smaller cities had minor traffic congestion and limited combustion particles from leaded petrol. From the perspective of the 20th century era of urban Pb pollution, St. John’s, NL, children have blood Pb characteristics of a small city. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Doubly nonlinear evolution equations with non-monotone perturbations in reflexive Banach spaces
The Effect of Chemical Composition on Grain Size and Formability of the Free-Lead Cu-30Zn Alloy: A Short Review
Analysis of Lead in Soils Adjacent to an Interstate Highway in Tampa, Florida
In order to assess the amount and distribution of lead pollution in soils adjacent to a major interstate highway serving the city of Tampa, Florida, a total of 224 samples were collected from 32 transects perpendicular to the roadway. The lead content was measured using atomic absorption spectrophotometry. The highest levels of lead were found at distances of 81, 243, and 729 cm from the road. The results show that there is a weak negative correlation between soil lead and the distance from the roadside, as well as with traffic density. The weakness of the relationship is a result of confounding variables such as turbulence and other microclimatic factors, downslope movement of soils overtime, and human action such as construction and highway landscaping. Nevertheless, over one-third of the samples collected in the study area contain more than 500 μg g−1 lead, levels considered to be hazardous by the United States Centers for Disease Control and the Environmental Protection Agency