3,848 research outputs found
The Immanent Contingency of Physical Laws in Leibniz’s Dynamics
This paper focuses on Leibniz’s conception of modality and its application to the issue of natural laws. The core of Leibniz’s investigation of the modality of natural laws lays in the distinction between necessary, geometrical laws on the one hand, and contingent, physical laws of nature on the other. For Leibniz, the contingency of physical laws entailed the assumption of the existence of an additional form of causality beyond mechanical or efficient ones. While geometrical truths, being necessary, do not require the use of the principle of sufficient reason, physical laws are not strictly determined by geometry and therefore are logically distinct from geometrical laws. As a consequence, the set of laws that regulate the physical laws could have been created otherwise by God. However, in addition to this, the contingency of natural laws does not consist only in the fact that God has chosen them over other possible ones. On the contrary, Leibniz understood the status of natural laws as arising from the action internal to physical substances. Hence the actuality of physical laws results from a causal power that is inherent to substances rather than being the mere consequence of the way God arranged the relations between physical objects. Focusing on three instances of Leibniz’s treatment of contingency in physics, this paper argues that, in order to account for the contingency of physical laws, Leibniz maintained that final causes, in addition to efficient and mechanical ones, must operate in physical processes and operations
Combined analysis of KamLAND and Borexino neutrino signals from Th and U decays in the Earth's interior
The KamLAND and Borexino experiments have detected electron antineutrinos
produced in the decay chains of natural thorium and uranium (Th and U
geoneutrinos). We analyze the energy spectra of current geoneutrino data in
combination with solar and long-baseline reactor neutrino data, with
marginalized three-neutrino oscillation parameters. We consider the case with
unconstrained Th and U event rates in KamLAND and Borexino, as well as cases
with fewer degrees of freedom, as obtained by successively assuming for both
experiments a common Th/U ratio, a common scaling of Th+U event rates, and a
chondritic Th/U value. In combination, KamLAND and Borexino can reject the null
hypothesis (no geoneutrino signal) at 5 sigma. Interesting bounds or
indications emerge on the Th+U geoneutrino rates and on the Th/U ratio, in
broad agreement with typical Earth model expectations. Conversely, the results
disfavor the hypothesis of a georeactor in the Earth's core, if its power
exceeds a few TW. The interplay of KamLAND and Borexino geoneutrino data is
highlighted.Comment: 12 pages, including 6 figure
Adult attentional functioning in families with children diagnosed as attention-deficit hyperactivity disorder
The purpose of this study was to explore what differences, if any, existed between individuals and families with or without children diagnosed as Attention-deficit Hyperactivity Disorder. Information was gathered to identify subjects according to such demographic and situational variables as age, race, education, occupation, income, and performance on tasks requiring sustained attention and concentration. to further understand possible etiology each subject completed a neuropsychological battery. Collected data was analyzed to determine if the differences were significant.;The subjects were selected from the author\u27s private practice and the local churches and schools that refer to that practice. Each subject completed a biographical questionnaire, the Gordon Diagnostic System (GDS) and the Luria-Nebraska Neuropsychological Battery, Form I, Adult version (LNNB). Chi-square analysis, t-tests, and difference of proportions tests were used to examine the collected data.;The groups were similar in terms of age. There were no statistically significant differences between groups on the LNNB. Several of the differences on the GDS measures of vigilance and distractibility did not achieve statistical significance.;Significant differences were noted on variables including education levels, response times during measures of sustained attention, concentration and distractibility, and historical behavioral checklists. A trend analysis of the findings was offered suggesting visual processing as contributing to the delays in response time. The performance of individuals demonstrating problems with attention, concentration, and distractibility revealed significant problems with writing and mathematics. Implications, conclusions, and suggestions for further research were offered
Determinants of a Digital Divide Among Able-Bodied Older Adults: Does “Feeling Too Old” Play a Role?”
While younger adults have embraced internet technology, older adults have lagged behind in internet adoption. An age-based digital divide has developed globally. This is a concern because digital literacy is becoming an essential, rather than an optional, skill. This paper investigates the reasons why some able-bodied older adults with access to the internet choose not to use the internet. Previous studies of the age-based digital divide have identified income and education, and perceived need, as factors that influence internet use. This paper adds to knowledge on the age-based digital divide by studying the internet behavior of able-bodied older adults with internet access (rather than all older adults) and by investigating the association between “feeling too old to use the internet” and the internet use decision. This paper offers suggestions for bridging the age-based digital divide and discusses whether this divide will continue as younger adults, who are digital natives, become older adults
Marine biodiversity: A science roadmap for Europe
In the past ten years, Europe has made significant progress in marine biodiversity research and knowledge generation owing to strong support, funding, and coordination of research effort. However, there is still a major knowledge deficit and many of the important programmes and initiatives which have driven this progress have now ended. While biodiversity policy has also advanced, Europe has failed to achieve the biodiversity targets it has set itself. To meet these targets, effective science-based decisions and management will be necessary. This requires good science, strong European research collaboration, enhanced observing and research capacities, and effective science-policy interfaces
Optimal indicators of socioeconomic status for health research
Objectives: This paper examines the relationship between various measures of SES and mortality for a representative sample of individuals. ; Methods: Data are from the Panel Study of Income Dynamics. Sample includes 3,734 individuals aged 45 and above who participated in the 1984 interview. Mortality was tracked between 1984 and 1994 and is related to SES indicators using Cox event-history regression models. ; Results: Wealth has the strongest associations with subsequent mortality, and these associations differ little by age and sex. Other economic measures, especially family-size-adjusted household income, have significant associations with mortality, particularly for nonelderly women. ; Conclusions: By and large, the economic components of SES have associations with mortality that are at least as strong as, and often stronger than, more conventional components (e.g., completed schooling, occupation).Income distribution
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