66 research outputs found
Barium Concentration in Rock Varnish: Implications for Calibrated Rock Varnish Dating Curves
Cation-ratio dating of rock varnish is a recently developed technique for obtaining surface exposure ages of a wide variety of geomorphic surfaces. As originally proposed, the technique utilizes a ratio among minor cations [(K+Ca)/Ti] in rock varnish. Although this varnish cation ratio is related to the Ti concentration, it can also be affected by the presence of Ba that may be partially included in the analyzed concentration of Ti. Barium is a minor constituent found in virtually all rock varnishes sampled from the Lake Mead area, Las Vegas Valley, and the Crater Flat region of southern Nevada. Barium is heterogeneously distributed in rock varnish, associated predominantly with Mn and secondarily with sulfur (detrital barite). Barium concentrations are apparently greater in varnishes found on young surfaces (\u3c 100 ka) than in varnishes found on older surfaces (\u3e 500 ka), and they are apparently greater in varnishes on low elevation surfaces than in varnishes on hill-slope or ridge deposits.
In energy dispersive spectroscopy (EDS), Ba Lα and Lβ peaks overlap with Ti Kα and Kβ peaks. Unless decomposed , the overlapping peaks may yield erroneously large values for Ti. We have compared the effect of Ba concentration on calculated varnish cation ratios using: (I) quantitative EDS with the scanning electron microscope (SEM) that decomposes Ti and Ba peaks; (2) quantitative wavelength-dispersive spectroscopy (WDS) with an electron probe microanalyzer (EPM); (3) semiquantitative EDS with the SEM that decomposes Ti and Ba peaks; and (4) semi-quantitative EDS with the SEM that does not decompose Ti and Ba lines. Results suggest small amounts of Ba relative to Ti will not significantly change the value of the calculated varnish cation ratio with or without decomposition. However, if Ba concentrations are high relative to Ti, the effect on cation ratios is pronounced, resulting in anomalously low cation ratios. As younger varnishes and varnishes on topographically lower surfaces apparently have higher Ba concentrations, the effect of Ba on cation ratios calculated for younger rock varnishes and lower surfaces will be greater
Recommended from our members
Structure of the Tshirege Member of the Bandelier Tuff at Mesita del Buey, Technical Area 54, Los Alamos National Laboratory
The geological structure of the Tshirege Member of the Bandelier Tuff at Mesita del Buey, Technical Area 54, was examined using precise surveying of the contact between tuff units Iv and 2 for 3.5 km along the north wall of Pajarito Canyon and 0.6 km along the north wall of a tributary to Caiiada del Buey. Estimated structure contours on this contact indicate typical strikes of N40E to N70E along this part of Mesita del Buey, although the apparent stfike of the tuff is E-W at the western part of the survey. Typical dips are 1.OO to 2.0o to the east or southeast, with an estimated maximum dip of 3.2o near the west end of Material Disposal AreaG. Thirty seven faults with vertical displacements of 5 to 65 cm were observedin outcrops along the Pajarito Canyon traverse, and, due to the incomplete exposure of the contact between unit lV and unit 2, many more faults of this magnitude undoubtedly exist. The faults have a wide range in strike and have either down-to-the-west or down-to-the-east components of offset, although about 65% of the observed displacement is down-to-the-west or northwest. The general absence of larger-scale offsets or inflections along the contact between units lV and 2 in areas where the small-scale faults were observed suggests that they are not associated with major fault zones. Instead, these faults may record distributed secondary deformation across the Pajarito Plateau associated with large earthquakes on the main Pajarito fault zone 8 to 11 km to the west, or perhaps earthquakes on other faults in the region. The survey data also suggest that a 150 to 250 m wide zone of greater magnitude faulting is present near the west end of the traverse associated with a horst-and-graben structure displaying about 1.5 to 3.5 m of offset on individual faults, although the total amount of offset across this structure and its orientation are not known
Recommended from our members
Erosion and deposition on the Pajarito Plateau, New Mexico, and implications for geomorphic responses to late Quaternary climatic changes
The Pajarito Plateau of northern New Mexico contains a rich and diverse record of late Quaternary landscape changes in a variety of geomorphic settings that include gently-sloping mesa tops, steep canyon walls, and canyon bottoms. A broad range of investigations during the past decade, motivated by environmental and seismic hazard concerns, have resulted in examination of the characteristics, stratigraphy, and age of sediments and soils at numerous locations throughout the Plateau. Geochronologic control is provided by >140 radiocarbon dates supplemented by soil characterization and tephrochronology. In this paper we first summarize some of the results of recent and ongoing work on late Quaternary deposits on the Pajarito Plateau, illustrating both the complexity of the geomorphic record and some common elements that have been observed in multiple locations. We then use these observations, in combination with other work in the Southwest, to make some inferences about the local geomorphic response to regional climatic changes. Because the geomorphic and paleoclimatic records are fragmentary, and because the relations between large scale climate changes and local variations in precipitation, vegetation, and geomorphic processes are not fully understood, many uncertainties exist concerning the response of the local landscape to past climatic fluctuations. In addition, variations in local landscape sensitivity related to prior erosional history and spatial variations in vegetation, and the localized nature of many storms, probably contribute to the complexity of the geomorphic record. Nevertheless, the work discussed in this paper suggests a strong relation between regional climatic changes and local geomorphic history, and provides a framework for considering relations between modem processes, the record of past landscape changes, and future erosion and deposition on the Plateau and in surrounding areas
Ethanol reversal of tolerance to the respiratory depressant effects of morphine
Opioids are the most common drugs associated with unintentional drug overdose. Death results from respiratory depression. Prolonged use of opioids results in the development of tolerance but the degree of tolerance is thought to vary between different effects of the drugs. Many opioid addicts regularly consume alcohol (ethanol), and post-mortem analyses of opioid overdose deaths have revealed an inverse correlation between blood morphine and ethanol levels. In the present study, we determined whether ethanol reduced tolerance to the respiratory depressant effects of opioids. Mice were treated with opioids (morphine, methadone, or buprenorphine) for up to 6 days. Respiration was measured in freely moving animals breathing 5% CO(2) in air in plethysmograph chambers. Antinociception (analgesia) was measured as the latency to remove the tail from a thermal stimulus. Opioid tolerance was assessed by measuring the response to a challenge dose of morphine (10 mg/kg i.p.). Tolerance developed to the respiratory depressant effect of morphine but at a slower rate than tolerance to its antinociceptive effect. A low dose of ethanol (0.3 mg/kg) alone did not depress respiration but in prolonged morphine-treated animals respiratory depression was observed when ethanol was co-administered with the morphine challenge. Ethanol did not alter the brain levels of morphine. In contrast, in methadone- or buprenorphine-treated animals no respiratory depression was observed when ethanol was co-administered along with the morphine challenge. As heroin is converted to morphine in man, selective reversal of morphine tolerance by ethanol may be a contributory factor in heroin overdose deaths
Patterns and universals of mate poaching across 53 nations : the effects of sex, culture, and personality on romantically attracting another person’s partner
As part of the International Sexuality Description Project, 16,954 participants from 53 nations were administered an anonymous survey about experiences with romantic attraction. Mate poaching--romantically attracting someone who is already in a relationship--was most common in Southern Europe, South America, Western Europe, and Eastern Europe and was relatively infrequent in Africa, South/Southeast Asia, and East Asia. Evolutionary and social-role hypotheses received empirical support. Men were more likely than women to report having made and succumbed to short-term poaching across all regions, but differences between men and women were often smaller in more gender-egalitarian regions. People who try to steal another's mate possess similar personality traits across all regions, as do those who frequently receive and succumb to the poaching attempts by others. The authors conclude that human mate-poaching experiences are universally linked to sex, culture, and the robust influence of personal dispositions.peer-reviewe
Are men universally more dismissing than women? Gender differences in romantic attachment across 62 cultural regions
The authors thank Susan Sprecher (USA), Del
Paulhus (Canada), Glenn D. Wilson (England), Qazi
Rahman (England), Alois Angleitner (Germany),
Angelika Hofhansl (Austria), Tamio Imagawa
(Japan), Minoru Wada (Japan), Junichi Taniguchi
(Japan), and Yuji Kanemasa (Japan) for helping with
data collection and contributing significantly to the
samples used in this study.Gender differences in the dismissing form of adult romantic attachment were investigated as part of the International Sexuality Description Project—a survey study of 17,804 people from 62 cultural regions. Contrary to research findings previously reported in Western cultures, we found that men were not significantly more dismissing than women across all cultural regions. Gender differences in dismissing romantic attachment were evident in most cultures, but were typically only small to moderate in magnitude. Looking across cultures, the degree of gender differentiation in dismissing romantic attachment was predictably associated with sociocultural indicators. Generally, these associations supported evolutionary theories of romantic attachment, with smaller gender differences evident in cultures with high–stress and high–fertility reproductive environments. Social role theories of human sexuality received less support in that more progressive sex–role ideologies and national gender equity indexes were not cross–culturally linked as expected to smaller gender differences in dismissing romantic attachment.peer-reviewe
Recommended from our members
Health and safety plan for operations performed for the Environmental Restoration Program
This document constitutes the generic health and safety plan for the Environmental Restoration Program (ERP). It addresses the health and safety requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA); Occupational Safety and Health Administration (OSHA) 29 CFR 1910.120 standard; and EG G Idaho, Inc. This plan is a guide to individuals who must complete a health and safety plan for a task performed for the EPR. It contains a task specific addendum that, when completed, specifically addresses task specific health and safety issues. This health and safety plan reduces the time it takes to write a task specific health and safety plan by providing discussions of requirements, guidance on where specific information is located, and specific topics in the Addendum that must be discussed at a task level. This format encourages a complete task specific health and safety plan and a standard for all health and safety plans written for ERP
Recommended from our members
Structure of Mesita del Buey at TA-54, Los Alamos National Laboratory, New Mexico
The geological structure of Mesita del Buey at Technical Area 54 (TA-54) was examined using precise surveying of the contact between units 1v and 2 of the Tshirege Member of the Bandelier Tuff at 3.5 km along the north wall of Pajarito Canyon and 0.6 km along the north wall of a tributary to Canada del Buey. Estimated structure contours on this contact indicate typical strikes of N40E to N70E along this part of Mesita del Buey, although the apparent strike of the tuff is E-W at the western part of the survey. Typical dips are 1.0{degree} to 2.0{degree} to the east or southeast, with an estimated maximum dip of 3.2{degree} near the west end of Material Disposal Area G. Thirty seven faults with vertical displacements of 5 to 65 cm were observed in outcrop along the Pajarito Canyon traverse, and, due to the incomplete exposure of the unit 1v-unit 2 contact, many more faults of this magnitude undoubtedly exist. The faults have a wide range in strike and have either down-to-the-west and down-to-the-east components of offset, although about 65% of the observed displacement is down-to-the-west or northwest. These faults are not clearly associated with major fault zones, indicated by the general absence of larger-scale offsets or inflections along the unit 1v-unit 2 contact in areas where the small-scale faults were observed; they may instead record distributed secondary deformation across the Pajarito Plateau associated with large earthquakes on the main Pajarito fault zone 8--11 km to the west, or perhaps other faults in the region. The survey data also suggest that a 150--250 m wide zone of greater magnitude faulting is present near the west end of the traverse associated with a horst-and-graben structure displaying about 1.5--3.5 m of offset on individual faults, although the total amount of offset across this structure and its orientation are not known
- …