66 research outputs found

    Barium Concentration in Rock Varnish: Implications for Calibrated Rock Varnish Dating Curves

    Get PDF
    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

    Ethanol reversal of tolerance to the respiratory depressant effects of morphine

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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
    • …
    corecore