Characteristics of ESR signals and TLCLs of quartz included in various source rocks and sediments in Japan: A clue to sediment provenance

The variation of electron spin resonance (ESR) signal intensities and thermoluminescence colour images (TLCIs) of quartz was investigated in the present study for various rocks and sediments in Japan, to discuss the possibilities of identifying the sediment provenance. The ESR signal intensity of the E₁’ centre in the same grain size in granitic quartz varies from sample to sample, except for that in Quaternary samples of volcanic sediment, which is very low, close to the noise level. It was found that the diagram, ESR intensities of Al versus Ti-Li centre signal intensities, distinguish volcanic from the same grain size in granitic quartz as well as distinguish individual tephra from another. The TLCIs from volcanic quartz and some granitic quartz samples is almost red and that from the rest of granitic and metamudstone quartz is blue as results of TLCIs although the emission intensities are different. Our results suggest that examining the multiple-centre signal intensities of ESR and the TLCIs are effective to identify the source of quartz and to estimate the sediment provenance.     

Construction of a quartz OSL standardised growth curve (SGC) for aeolian samples from the Horqin dunefield in northeastern China

It has been suggested that the standardised growth curve (SGC) method can be used to de-terminate D_e accurately and reduce the measurement time. However, different opinions regarding the applicability of the SGC method exist. In this paper, we report the construction of quartz OSL SGC for 35 aeolian samples from different parts of the Horqin dunefield in northeastern China, and then test their applicability for D_e determination. Our results suggest that: 1) up to a regeneration dose of 80 Gy, the SGC of the Horqin dunefield can be fitted using the exponential plus linear equation, with the r² value of 0.97, and all the regeneration dose points closely stick to the fitting line, implying that all samples share a very similar dose-response curve; 2) for samples with Des ranging from 1 to 50 Gy, the ratios of SAR D_e to SGC D_e fall within the range of 0.9–1.1, and the average ratio of SAR D_e to SGC D_e is 1.01±0.01, close to unity. Therefore, the construction of SGC is correct, and the SGC is an effective procedure for accurate D_e determination for samples from the study area.     

An attempt to estimate firing temperature using OSL pre-dose sensitization of quartz

The estimation of firing temperature of ceramics using methods based on pre-dose sensitization of the 110°C TL peak of quartz have yielded incoherent results. Recently the fast component of the CW-OSL of quartz has been observed to have pre-dose characteristics similar to that of the 110°C TL peak. The motivation for this study has been to look into the feasibility of this signal, the OSL counter part of pre-dosed TL emission, for the firing temperature identification. The variation in the sensitization ratio of the TL and OSL emissions with different heating temperatures was also utilized to unveil the firing temperature mark of the specimen.     

Holy Nigerian Nationalisms and Apocalyptic Visions of the Nation

Abstract. This article examines the rise of religious political radicalism and its critique and appropriation of secular Nigerian nationalism. It argues that the revitalisation and radicalisation of religion in Nigeria is both an expression of the deep legitimacy crisis confronting secular nationalism and a means of resolving such a crisis. Religion is seen as fundamental to nationalism because it provides the sacred normative essence that ultimately enables individuals and communities to accept as permanent and meaningful the suffering which is integral to a national identity. In ‘holy nationalism’, the collective emotional force of nationalism merges with religion so that the two are one and the same. God chose a particular people and promised them a particular land.     

An assessment of the luminescence sensitivity of Australian quartz with respect to sediment history

This study provides a preliminary systematic characterisation of OSL sensitivity, with respect to sediment history, of single grains of Australian quartz from a variety of source rocks and depositional contexts. Samples from two distinct lithologies and with relatively short modern sedimentary histories were compared in an examination of the influence of rock type on OSL sensitivity. Sediments derived from weathered sandstone were found to be brighter than those from metamorphosed schists, suggesting that sensitivity may be inherited from the source rock and its earlier sedimentary history. Secondly, quartz from the same source, but different modes of deposition, was compared to assess the effect on sensitivity of nature of exposure to light during the most recent bleaching event. Quartz grain sensitivity appears not to vary depending on the mode of sediment deposition, suggesting that the nature of exposure to light during deposition is less important in the sensitisation process. This study highlights the complexity and variety of natural sedimentary quartz, demonstrating the limitations of an investigation based solely on OSL sensitivity. Further systematic investigation into the physical, geological and geomorphological characteristics of sediments is proposed to better understand the mechanisms of luminescence sensitisation in quartz.     

Computation of the zonally-averaged circulation driven by heating due to radiation and turbulence

In a zonally-averaged dynamic model the steady state circulation of the middle atmosphere between 10 and 110 km altitude has been calculated for solstice. To investigate the combined effect of turbulent heat conduction and dissipation of eddy kinetic energy on the mean circulation, the dissipative heating has been parameterized in terms of the buoyancy term modified by a residual Richardson number. It is shown that turbulence will result in net heating of the mesopause region to be consistent with a zero mass flux through a pressure surface. It is also demonstrated that the combined effect of turbulent heat conduction and dissipation can modify the mean circulation remarkably if the Richardson number is made latitude-dependent.     

ESR dose response of Al center measured in quartz samples from the Yellow River (China): Implications for the dating of Upper Pleistocene sediment

The ESR dating method requires to describe the evolution of the ESR signal intensities vs. increasing gamma doses, then to extrapolate the equivalent dose of radiation received by the sample since its deposition using mathematical fitting. The function classically used to describe the growth curves of ESR aluminium signal in quartz was recently discussed and challenged for Lower Pleistocene sediments. In the present work, some alluvial sediments sampled in Upper Pleistocene fluvial terraces of the Yellow River system (China) permit us to test the application of another extrapolation function (linear + exponential) recently proposed for Lower Pleistocene sediments. The equivalent doses obtained here for the recent deposits of the Yellow River system and the corresponding ages are promising and indicate the potential of ESR to date quartz deposits from Upper Pleistocene times.     

Constraints on the precision of SAR in equivalent dose estimations close to saturation in quartz

Difficulties in evaluating accurate equivalent doses for Late Quaternary sediments from the south coasts of Greece arose in the course of SAR measurements. Large scatter among apparent equivalent doses perplexed the evaluation of accurate mean estimates in circumstances where very large doses were involved. Besides, dose recovery experiments revealed that when intersection of the natural signal occurs onto the saturating segment of the growth curve, a distinct relationship between D_e and growth curve shape occurs. At very low slope angles, SAR tends to overestimate the recovered dose. The mechanism which controls the spread in equivalent dose estimation is investigated.     

Wife Seclusion and the Spatial Praxis of Gender Ideology in Nigerian Hausaland

In much of Nigerian Hausaland the prevailing religio-cultural ideology of female seclusion (if not always the practice) impinges on married Muslim Hausa women to a greater, or lesser, degree. This article examines the intimate relationships between space, gender and ideology in contemporary rural Hausa society, showing the social construction (and connectedness) of gender identities and associated spatial identities, thus illustrating how spatial praxis is based on hegemonic patriarchal gender ideology. Observations and interview material gathered from a village case study in Kano State demonstrate how gender divisions correspond with the ideology and contemporary practice of wife seclusion. Intersecting patterns of gender, space and time are revealed by detailed analyses of time- and space-use data, which scrutinise men's and women's daily activities and mobility patterns. The cross-cutting of gender with class, age and marital status is shown to be highly significant in determining everyday experiences of spatial praxis, especially for women. A materialist feminist theoretical framework is used to explain this gendered geography of Nigerian Hausaland in which men's and women's worlds are spatially segregated, yet complexly interlocked and interdependent beyond simple public‐private divisions of ‘female’ household compounds (private space) and ‘male’ public space. For this peasant society, aspects of the rural economy and ideology emerge as powerful factors in determining the nature of seclusion as part of gender praxis. It is argued that due to various cultural and religious factors socio-economic development in Northern Nigeria has not been translated into improved autonomy for Hausa women.     

Response of cathodoluminescence of alkali feldspar to He+ ion implantation and electron irradiation

Cathodoluminescence (CL) of minerals such as quartz and zircon has been extensively studied to be used as an indicator for geodosimetry and geochronometry. There are, however, very few investigations on CL of other rock-forming minerals such as feldspars, regardless of their great scientific interest. This study has sought to clarify the effect of He+ ion implantation and electron irradiation on luminescent emissions by acquiring CL spectra from various types of feldspars including anorthoclase, amazonite and adularia. CL intensities of UV and blue emissions, assigned to Pb²⁺ and Ti⁴⁺ impurity centers respectively, decrease with an increase in radiation dose of He⁺ ion implantation and electron irradiation time. This may be due to decrease in the luminescence efficiencies by a change of the activation energy or a conversion of the emission center to a non-luminescent center due to an alteration of the energy state. Also, CL spectroscopy of the alkali feldspar revealed an in-crease in the blue and yellow emission intensity assigned to Al-O^?-Al/Ti defect and radiation-induced defect centers with the radiation dose and the electron irradiation time. Taken together these results indicate that CL signal should be used for estimation of the α and β radiation doses from natural radionuclides that alkali feldspars have experienced.     

Subterranean transport and deposition of quartz by ants in sandy sites relevant to age overestimation in optical luminescence dating

An artificial layered sandy site was created using a combination of native sand and colored sand (3 parts native uncolored quartz, 1 part colored quartz) in Apalachicola National Forest near Tallahassee, Florida. Twelve layers of sand, each 1 by 1 m in horizontal extent by 10 cm in thickness were emplaced to a depth of 2 m followed by implantation at the surface of a Florida harvester ant (Pogonomymrex badius) colony (the lower two layers were 50 cm thick). The colony excavated a nest, and after 7 months, the sand layers were excavated to the base to test the hypothesis that sand grains were moved upward within the ant nest without reaching the surface. The ants penetrated 11 of the 12 colored layers reaching a depth of 130 cm. Thirty nine sticky-acetate peels of ant chamber floors were collected and colored sand grains were counted under a microscope. More than 16,000 grains were identified in layers that did not originally host them. Of these, more than 80% were unambiguously moved upward. This means that possibly as many as 54,000 upwardly mobile grains were present (ratio of 3:1 uncolored to colored). In relation to optical luminescence (OSL) dating, this means that grains that would not have been optically zeroed by transport to the surface (defined here as subterranean-transported) were present in abundance, and that if the site was ancient, there would have been found many grains that were older than the layers they presently reside in, even if only one colony of harvester ants had disturbed the layers. This is in addition to the fact that backfilling of chambers and tunnels may contribute even more significantly to the presence of a subterranean-transported component of an OSL sample. We conclude that ants can significantly affect the age distributions in sandy archaeological sites. Multiple examples of such disturbances have been documented in the literature. Most relevant to our results are recent studies of the OSL chronology of Pre-Clovis-age and Palaeoindian age archaeological sites in sandy environments in North America that may have been compromised by ant bioturbation of quartz sand grains. Here we have examined in detail the potential effects of one episode of ant nest-building on the age overestimation of affected sediments. From this we found that as few as 12 episodes of bioturbation involving backfilling of chambers in the same volume of sand could lead to the presence of 1 contaminant grain per 50 grains of sample.     

Nigerian Oil and Exchange Rates: Indicators of ‘Dutch Disease’

This article assesses the impact of expanding oil revenues on non-oil sectors of the Nigerian economy from 1960 to 1985/6. Emphasis is placed on the effects of exchange rate appreciation during the 1970s on the agricultural, manufacturing and non-traded goods sectors. The analysis is conducted within a Dutch disease context. Two main conclusions are that the decline of Nigerian agriculture during these years can be attributed to a combination of low real producer prices and insufficient government investment, as well as the overvalued Nigerian naira; and that the high real exchange rate may have benefited the manufacturing sector.     

OSL and TL characteristics of fine grain quartz from Mongolian prehistoric pottery used for dating

The OSL, post-IR OSL and pulsed post-IR OSL applied to polymineral grains and calculated by fitting to the data the contributions from fast, medium and slow components revealed that the polymineral samples under study are dominated by the medium component. An increase in D _e ’s with increasing integration intervals was observed, which is considered as an indication of increasing medium and decayed fast component; and the equivalent doses obtained using different components or minerals reflect also the shape of the dose distributions. The identified fast component in polymineral sample has photoionization cross section of 1.2±0.02 × 10^?17 cm². The present study shows the usefulness of the application of different luminescence techniques combined with fitting procedures as a check which should be adopted in dating protocols. Based on luminescence ages obtained on poly-mineral grains from prehistoric pottery samples from the Boroo settlement, Mongolia, which are in agreement with independent age control by ¹⁴C on charcoal material, it is argued that the manufacturing of Xiongnu — pottery at this site lasted until ca. 130±75 AD.     

Intellectuals,Economic Reform and Social Change: Constraints and Opportunities in the Formation of a Nigerian Technocracy

Crisis and economic reforms have changed the status of intellectuals and their relations with dominant élites and policy makers. Because of the technical and ideological nature of these reforms, policy makers have tended to rely on intellectuals as opposed to bureaucrats to shape the agenda of change. This has converted a large number of intellectuals into technocrats and undermined the fabric of academic life in universities. Nowhere is this more pronounced than in developing countries with a large middle class and an economic or financial base that ensures some degree of independence from the multilateral financial institutions. Understanding the success or failure of economic reforms in developing countries requires some analysis of the complex relations between technocrats and political leaders and the societal constraints both sets of actors face. This article explores these issues in the context of Nigeria, whose academic community, bureaucrats and professionals grew in leaps and bounds in the 1970s, following an oil-induced boom. The crisis of the 1980s led to attempts at economic reform and a highly programmed strategy of political change in which academics played a leading role. The article examines the effectiveness of intellectuals in government, and compares the Nigeria case with technocratic experiments in Ghana, Botswana and Côte d?Ivoire.     

历史性的地理陈述与阅读

我们基本上是通过对文本或文献的阅读,才可能重构关于历史时期的地理景观和地理知识,才可能理解历史时期地理景观与地理知识对于古人和今人的意义。因此本文考察了历史文本或文献中地理陈述与地理景观和地理知识之间的各种关系,以及当前对这些地理陈述的不同阅读方法。