The testing of geomagnetic reversal models: recent developments

1982 ◽  
Vol 306 (1492) ◽  
pp. 147-159 ◽  
Keyword(s):  
Conclusive Evidence ◽  
Zonal Harmonic ◽  
Virtual Geomagnetic Pole ◽  
Data Set ◽  
Geomagnetic Reversal ◽  
Polarity Transition ◽  
Recent Developments ◽  
Geomagnetic Pole ◽  
Field Geometry ◽  
Field Behaviour

The number of available palaeomagnetic records displaying detailed transitional field behaviour has increased significantly over the past few years. The expanded data set of transitions now includes records of sequential reversals from the same site locality as well as multiple recordings of a particular reversal from widely separated sites. Such data are most useful with regard to the testing of geomagnetic reversal models. First, records of successive reversals may make it possible to distinguish whether transitional fields originate primarily with the configurational characteristics of the reversing geodynamo or whether a non-reversing portion of the field is responsible. Such an analysis does not yet provide conclusive evidence in support of either hypothesis. Second, multiple records from distant sites furnish the best possible data with regard to the determination of the harmonic content of particular transitional fields. In this regard, two quite independent, testable models have been applied to the several recordings of the Matuyama-Brunhes transition. Findings support the hypothesis that the intermediate field geometry during this particular polarity transition was indeed controlled by non-dipole zonal harmonic terms. Moreover, analysis of the paths of the virtual geomagnetic pole associated with the available records strongly suggests that the most extreme dominance of transitional fields by axisymmetric components occurs during the onset of the reversal, a finding that now has support on purely theoretical grounds. Finally, field behaviour associated with existing igneous-recorded palaeomagnetic excursions is not unlike that observed at the onset of field reversals. Hence, there is growing evidence in support of the hypothesis that attempts by the geodynamo to reverse are not always successful. These recordings of apparent abortive reversals may be of considerable value with regard to our understanding of transitional fields and geomagnetic reversal.

Geochronological and paleomagnetic studies of small carbonatite intrusions of the Udzha uplift (Tomtor massif, northeast of the Siberian platform)

2021 ◽  
Author(s):  
Aleksandr Pasenko ◽  
Ivanov Alexey ◽  
Malyshev Sergey ◽  
Travin Alexey
Keyword(s):  
Siberian Platform ◽  
Conclusive Evidence ◽  
Snowball Earth ◽  
Paleomagnetic Data ◽  
Russian Science ◽  
Virtual Geomagnetic Pole ◽  
River Bank ◽  
High Temperature Component ◽  
Geomagnetic Pole ◽  
Temperature Component

<p>Paleomagnetic data obtained from Neoproterozoic glacial and glacier-associated sedimentary rocks indicate that they were formed at near equatorial latitudes. Based on these data, the Snowball Earth hypothesis was proposed [Kirschvink, 1992]. According to this hypothesis, during the Neoproterozoic glaciations, the entire planet (including the oceans) was completely covered with ice. Although evidence is emerging that does not support this hypothesis, there is still no conclusive evidence that it is not true [Sansjofre et al., 2011].</p><p>It is worth noting that the Snowball earth hypothesis is based on paleomagnetic data. At the same time, the available paleomagnetic data for the Neoproterozoic-Early Cambrian [Meert, Van der Voo, 2001; Shatsillo et al, 2005; Abrajevitch, Van der Voo, 2010; Pavlov et al., 2018] difficult to interpret in terms of the Geocentric Axial Dipole hypothesis. This imposes serious restrictions on the possibility of correctly constructing paleomagnetic reconstructions.</p><p>For the development and testing of a model of the geomagnetic field of the Neoproterozoic, it is necessary to obtain a lot of high-quality paleomagnetic data. Data from well-dated magmatic bodies are especially valuable.</p><p>Within the framework of this work, we obtained paleomagnetic data from three carbonatite dikes (7 to 30 cm thickness) exposed in the Udzha river bank on the Udzha uplift in the northeastern part of the Siberian platform. These dikes are associated with the large alkaline Tomtor massif located 15 km to the west. Ar/Ar dating of phlogopite megacrysts gives an intrusion age of the dikes of 706.1±8.8 Ma. Coordinates of the virtual geomagnetic pole, calculated from the direction of the high-temperature component of magnetization: Φ=-20.7°; Λ=88.6°; Α95=3.4°.</p><p>Our report will present preliminary interpretation of these data, as well as their comparison with paleomagnetic data on close-aged objects in Siberia.</p><p><em>The research was supported by the Russian Science Foundation grant (19-77-10048).</em></p><p>References:</p>

scholarly journals Further evidence that psychopathology networks have limited replicability and utility: Response to Borsboom et al. (2017) and Steinley et al. (2017)

2017 ◽  
Author(s):  
Miriam K. Forbes ◽  
Aidan G.C. Wright ◽  
Kristian Eric Markon ◽  
Robert Krueger
Keyword(s):  
Mental Health ◽  
Conclusive Evidence ◽  
Estimation Methods ◽  
Data Set ◽  
National Comorbidity Survey Replication ◽  
Health And Wellbeing ◽  
Target Article ◽  
Network Methods ◽  
Recent Developments ◽  
Network Estimation

In our target article, we tested the replicability of four popular psychopathology network estimation methods that aim to reveal causal relationships among symptoms of mental illness. We started with the focal data set from the two foundational psychopathology network papers (i.e., the National Comorbidity Survey–Replication) and identified the National Survey of Mental Health and Wellbeing as a close methodological match for comparison. We compared the psychopathology networks estimated in each dataset—as well as in ten sets of random split-halves within each dataset—with the goal of quantifying the replicability of the network parameters as they are interpreted in the extant psychopathology network literature. We concluded that current psychopathology network methods have limited replicability both within and between samples, and thus have limited utility. Here we respond to the two commentaries on our target article, concluding that Steinley, Hoffman, Brusco and Sher’s (2017) findings—along with other recent developments in the literature—provide further conclusive evidence that psychopathology networks have poor replicability and utility.

scholarly journals A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes

2011 ◽  
Vol 3 (1) ◽  
pp. 19-42
Author(s):  
F. D'Ajello Caracciolo ◽  
A. Pignatelli ◽  
F. Speranza ◽  
A. Meloni
Keyword(s):  
Geomagnetic Field ◽  
Data Sets ◽  
Virtual Geomagnetic Pole ◽  
Data Set ◽  
Before And After ◽  
Geomagnetic Pole ◽  
Paleomagnetic Dating ◽  
Corrected Data ◽  
Original Observation ◽  
Corrected Curve

Abstract. Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleo)secular variation ((P)SV) are available. To this end, we re-evaluate the whole Italian geomagnetic directional data set, consisting of 833 and 696 declination and inclination (respectively) measurements carried out since 1640 AD at several localities. All directions were relocated via virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E), rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method) by French data (for period 1670–1789), and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962). Using post-1805 declination values, we obtain a 0.46 ± 0.19 °/yr westward drift of the geomagnetic field for Italy. Original observation years were modified considering such drift value to derive a drift-corrected relocated data set. Both data sets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000) and Pavon-Carrasco et al. (2009). However, the drift-corrected data set minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated data sets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. Curve comparison suggests that the regional model by Pavon-Carrasco et al. (2009) yields the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the XIX century. For the XX century, the global model by Jackson et al. (2000) yields more accurate inclination values, while the declinations from our drift-corrected curve seem to better represent the local field evolution, at least for the first half of the century.

Does Tax Increment Financing Pass the “But-for” Test in Missouri?

2019 ◽  
Vol 33 (3) ◽  
pp. 187-202
Author(s):  
Ahmed Rachid El-Khattabi ◽  
T. William Lester
Keyword(s):  
Economic Development ◽  
Kansas City ◽  
Time Series Data ◽  
Local Level ◽  
Conclusive Evidence ◽  
Series Data ◽  
Tax Increment Financing ◽  
Data Set ◽  
Development Indicators ◽  
The Impact

The use of tax increment financing (TIF) remains a popular, yet highly controversial, tool among policy makers in their efforts to promote economic development. This study conducts a comprehensive assessment of the effectiveness of Missouri’s TIF program, specifically in Kansas City and St. Louis, in creating economic opportunities. We build a time-series data set starting 1990 through 2012 of detailed employment levels, establishment counts, and sales at the census block-group level to run a set of difference-in-differences with matching estimates for the impact of TIF at the local level. Although we analyze the impact of TIF on a wide set of indicators and across various industry sectors, we find no conclusive evidence that the TIF program in either city has a causal impact on key economic development indicators.

scholarly journals Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Hyeon-Seon Ahn ◽  
Yuhji Yamamoto
Keyword(s):  
Dipole Moment ◽  
Mean Value ◽  
Good Precision ◽  
Dipole Strength ◽  
Virtual Geomagnetic Pole ◽  
Early Pliocene ◽  
Basaltic Rocks ◽  
Geomagnetic Pole ◽  
Bearing Materials ◽  
Fitting In

AbstractFinding the statistical intensity signatures of the Earth’s magnetic field over geologic time has helped understanding of the evolution of the Earth’s interior and its interactions with other integral parts of Earth systems. However, this has been often hampered by a paucity of absolute paleointensity (API) data, which are difficult to obtain primarily because of non-ideal magnetic behaviors of natural materials. Here, we present new API determination data with paleodirectional and rock magnetic analyses from basaltic rocks probably aged ~ 4‒5 Ma in Baengnyeong Island, Korea. Paleodirectional analysis obtained an overall mean direction of D = 347.3° and I = 38.3° (α95 = 4.9°, k = 113.4) corresponding to a virtual geomagnetic pole at 342.1° E and 70.2° N. Comprehensive rock magnetic analyses identified Ti-poor titanomagnetite with, in part, multi-domain (MD) particles as a main carrier of remanent magnetization. The Tsunakawa–Shaw (TS) method yielded 12 qualified API estimates with a high success rate, efficiently removing possible MD influences, and resulted in a mean value of 13.1 μT with good precision (1.7 μT, standard deviation). The Thellier method of the IZZI protocol with pTRM checks, coupled with the use of a bootstrap approach instead of the “conventional best-fitting” in API determination, gave 6.6‒19.7 μT as a 95% confidence interval of its mean API estimate, which supports the reliability of our TS-derived API mean estimate; but it is not considered in the final mean value because of the relatively large uncertainty. The virtual dipole moment corresponding to the TS-derived API mean, 2.9 (± 0.4) × 1022 Am2, is somewhat lower than the expectations of the past few Myr averages. Combined with a global API database, our new data implies a larger dispersion in the dipole moment during the early Pliocene than previously inferred. This also suggests that the issue of whether the early Pliocene average dipole strength was moderately high (> 5 × 1022 Am2) or consistent (4‒5 × 1022 Am2) should be discussed further.

scholarly journals Developments in the production of economics PhDs at four research-intensive universities in South Africa

2017 ◽  
Vol Volume 113 (Number 3/4) ◽  
Author(s):  
Phillip de Jager ◽  
Liezel Frick ◽  
Pieter van der Spuy ◽  
◽  
◽  
...  
Keyword(s):  
South African ◽  
Doctoral Education ◽  
Academic Departments ◽  
Current Status ◽  
Pedagogical Practice ◽  
Data Set ◽  
International Trends ◽  
Time Period ◽  
Recent Developments ◽  
Notable Increase

Abstract There is a national drive to increase PhD production, yet we know little about how this imperative takes shape within different disciplines. We therefore set out to explore recent developments and the current status of the PhD in economics at four South African research-intensive universities. A data set of all economics PhDs produced in these commerce faculties during the period 2008–2014 was analysed to determine whether the departments of economics responded to the call for increased doctoral production, and the role the PhD by publication might have played in the process. How an increase in quantity might influence doctoral education in the respective academic departments was also considered by supplementing the quantitative data with perspectives from heads of department at the four institutions. The notable increase in doctoral production over the time period studied shows that national and international trends have influenced doctoral education in economics departments within South African research-intensive universities. Increased usage of the PhD by publication has implications for policy and pedagogical practice within these departments, especially as there seems to be limited available supervisory capacity. Other changes in departmental practices, such as the entrenchment of a research culture and the promotion of collaborative research amongst students and staff, also contributed to maintain quality in doctoral education.

THE WANDERING PATH OF VIRTUAL GEOMAGNETIC POLE DURING THE LAST 6000 YEARS

1991 ◽  
pp. 253-262
Author(s):  
Wei Qingyun ◽  
Li Dongjie ◽  
Cao Guanyu ◽  
Zhang Weixi ◽  
Wang Shuangping
Keyword(s):  
Virtual Geomagnetic Pole ◽  
Geomagnetic Pole

Variance component estimates and genetic trends in a broiler breeder dam line using animal model methods

1995 ◽  
Vol 1995 ◽  
pp. 51-51
Author(s):  
A.J. Morri ◽  
G.E. Pollott
Keyword(s):  
Breeding Value ◽  
Data Set ◽  
Breeding Programs ◽  
Broiler Breeder ◽  
Value Prediction ◽  
Recent Developments ◽  
Commercial Breeding ◽  
Variance Component Estimates ◽  
Poultry Data ◽  
Genetic Trends

Recent developments in computing technology have seen the widespread implementation of animal models for parameter estimation and breeding value prediction in both experimental and commercial breeding programs. These techniques have several benefits over traditional least squares and index methods, including the ability to monitor genetic trends in die absence of an unselected control population. This paper reports heritabilities and genetic trends estimated from a large poultry data set for three broiler traits.

scholarly journals Certainty and uncertainty in science: the subjectivistic concept of probability in physiology and medicine.

1994 ◽  
Vol 267 (6) ◽  
pp. S113 ◽  
Author(s):  
R Jevning ◽  
R Anand ◽  
M Biedebach
Keyword(s):  
Relative Frequency ◽  
Physical Property ◽  
Conclusive Evidence ◽  
Probability Method ◽  
Large Collection ◽  
Physical Sciences ◽  
Physical Probability ◽  
Degree Of Belief ◽  
Recent Developments ◽  
Probability And Statistics

Most physiological scientists have restricted understanding of probability as relative frequency in a large collection (for example, of atoms). Most appropriate for the relatively circumscribed problems of the physical sciences, this understanding of probability as a physical property has conveyed the widespread impression that the "proper" statistical "method" can eliminate uncertainty by determining the "correct" frequency or frequency distribution. However, many relatively recent developments in the theory of probability and decision making deny such exalted statistical ability. Proponents of Bayes's subjectivist theory, for example, assert that probability is "degree of belief," a more tentative idea than relative frequency or physical probability, even though degree of belief assessment may utilize frequency information. In the subjectivist view, probability and statistics are means of expressing a consistent opinion (a probability) to handle uncertainty but never means to eliminate it. In the physiological sciences the contrast between the two views is critical, because problems dealt with are generally more complex than those of physics, requiring judgments and decisions. We illustrate this in testing the efficacy of penicillin by showing how the physical probability method of "hypothesis testing" may contribute to the erroneous idea that science consists of "verified truths" or "conclusive evidence" and how this impression is avoided in subjectivist probability analysis.

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