Secondary ferrimagnetic minerals in Welsh soils: a comparison of mineral magnetic detection methods and implications for mineral formation

A study of mineral magnetic parameters was carried out on a Late Pleistocene and Holocene sedimentary sequence (of nearly 18 m) from Lake Bledowo (central Poland). Sediments of Lake Bledowo have already been analysed for bulk sediment mineralogy and biogenic materials. The mineral magnetic stratigraphy confirms the major changes in palaeo-environmental conditions that have been deduced from other methods. The most important mineral magnetic change results from the authigenetic formation of ferrimagnetic greigite, Fe₃S₄, during the beginning of lacustrine conditions (± 12 000 yr BP). Our data also indicate a detrital origin of overlying ferrimagnetic iron oxides. It is suggested that they originate from brown soils developed on the boulder clay constituting the west side of the lake shore. Variations of ferrimagnetic iron oxide size are related to the early diagenetic processes in the sediment. Larger particles are present in periods with early diagenesis of organic matter in anoxic conditions. This indicates the dissolution of fine magnetic particles by iron-oxide-reducing bacteria and results in homogeneous magnetic grain sizes, despite their origin from soils, characterized by a multimodal grain-size distribution.     

Granitic magmatism,basement ages,and provenance indicators in the Malay Peninsula: Insights from detrital zircon U–Pb and Hf-isotope data

The Malay Peninsula lies on two continental blocks, Sibumasu and East Malaya, which are intruded by granitoids in two provinces: the Main Range and Eastern. Previous models propose that Permian–Triassic granitoids are subduction-related and syn-to post-collisional. We present 752 U–Pb analyses that were carried out on zircons from river sands in the Malay Peninsula; of these, 243 grains were selected for Hf-isotope analyses. Our data suggest a more complex Sibumasu–East Malaya collision history. ¹⁷⁶Hf/¹⁷⁷Hf_i ratios reveal that Permian–Triassic zircons were sourced from three magmatic suites: (a) Permian crustally-derived granitoids, (b) Early-Middle Triassic granitoids with mixed mantle–crust sources, and (c) Late Triassic crustally-derived granitoids. This suggests three Permian–Triassic episodes of magmatism in the Malay Peninsula, two of which occurred in the Eastern Province. Although the exact timing of the Sibumasu–East Malaya collision remains unresolved, current data suggest that it occurred before the Late Triassic, probably in Late Permian–Early Triassic. Our data also indicate that Sibumasu and East Malaya basements are chronologically heterogeneous, but predominantly of Proterozoic age. Some basement may be Neoarchaean but there is no evidence for basement older than 2.8 Ga. Finally, we show that Hf-isotope signatures of Triassic zircons can be used as provenance indicators.     

我即我食vs.我非我食——稳定同位素示踪人体代谢异常初探

稳定同位素分析揭示古代（现代）人群的食物结构,其原理为"我即我食",即人体组织的稳定同位素比值,与其消化吸收转化而来的食物组分,存在着一一对应关系。然而,当人体代谢发生异常时,这种对应关系将被打破,产生"我非我食"现象。目前,探究"我非我食"与古代（现代）人体的健康之联系,已成为生物医学和生物考古界的研究热点。颇为遗憾的是,迄今为止,我国尚无学者对此有所关注。为此,本文以中国北方地区2名代谢性异常患者（直肠癌为例）头发样本为研究对象,通过对人发系列的C、N稳定同位素分析,追踪癌症患者头发同位素值的变化趋势,探讨其生理病理因素与稳定同位素之间的内在关系。研究结果显示：人发C、N同位素比值的变化,与其健康状况密切相关。在直肠癌发病初期,患者的δ13C与δ15N值均呈现出上升趋势,这可能是癌细胞代谢活跃、更多地利用机体中的14N和12C所致,或者与癌细胞具有未知的、独特的代谢途径相关。最后,详细阐述了"我即我食"和"我非我食"的区别和联系,并对如何在我国开展此领域的研究进行了展望。     

3D seismic analysis of the gas hydrate system and the fluid migration paths in part of the Niger Delta Basin,Nigeria

Comprehensive qualitative and semi-quantitative seismic analysis was carried out on 3-dimensional seismic data acquired in the deepwater compressional and shale diapiric zone of the Niger Delta Basin using an advanced seismic imaging tool. The main aim of this work is to obtain an understanding of the forming mechanism of the gas hydrate system, and the fluid migration paths associated with this part of the basin. The results showed the presence of pockmarks on the seafloor and bottom simulating reflectors (BSRs) in the field, indicating the active fluid flux and existence of gas hydrate system in the area. In the area of approximately 195 km² occupying nearly 24% of the entire study field, three major zones with continuous or discontinuous BSRs of 3 to 7 km in length which are in the northeastern, southern and eastern part of the field respectively were delineated. The BSR is interpreted to be the transition between the free gas zone and the gas hydrate zone. The geologic structures including faults (strike-slip and normal faults), chimneys and diapirs were deduced to be the main conduits for gas migration. It is concluded that the biogenic gases generated in the basin were possibly transported via faults and chimneys by advection processes and subsequently accumulated under low temperature and high pressure conditions in the free gas zone below the BSR forming gas hydrate. A plausible explanation for the presence of the ubiquitous pockmarks of different diameters and sizes in the area is the transportation of the excessive gas to the seafloor through these mapped geologic structures.     

Spatial Access to Health Care Services and Disparities in Colorectal Cancer Stage at Diagnosis in Texas

Early diagnosis of colorectal cancer (CRC) is important for improving the survival rate of the disease. Disparities in CRC diagnosis among different population groups have persisted in the United States. This study examines whether spatial access to medical services contributes to disparities of late-stage diagnosis of CRC in Texas. Analysis results suggest that there are significant disparities in late-stage CRC diagnosis by race/ethnicity, socioeconomic status, and geographic location in Texas. It is concluded that spatial access to primary care is associated with CRC stage at diagnosis, but not with racial/ethnic and socioeconomic disparities.     

A Euler number-based topological computation model for land parcel database updating

Intersection relations are important topological considerations in database update processes. The differentiation and identification of non-empty intersection relations between new updates and existing objects is one of the first steps in the automatic incremental update process for a land parcel database. The basic non-empty intersection relations are meet, overlap, cover, equal and inside, but these basic relationships cannot reflect the complex and detailed non-empty relations between a new update and the existing objects. It is therefore necessary to refine the basic non-empty topological relations to support and trigger the relevant update operations. Such relations have been refined by several researchers using topological invariants (e.g., dimension, type and sequence) to represent the intersection components. However, the intersection components often include only points and lines, and the refined types of 2-dimensional intersection components that occur between land parcels have not been defined. This study examines the refinement of non-empty relations among 2-dimensional land parcels and proposes a computation model. In this model, an entire spatial object is directly used as the operand, and two set operations (i.e., intersection (∩) and difference (\)) are applied to form the basic topological computation model. The Euler number is introduced to refine the relations with a single 2-dimensional intersection (i.e., cover, inside and overlap) and to distinguish the refined types of 2-dimensional intersection components for the relations with multiple intersections. In this study, the cover and overlap relations with single intersections between regions are refined into seven cases, and nine basic types of 2-dimensional intersection components are distinguished. A composite computation model is formed with both Euler number values and dimensional differences. In this model, the topological relations with single intersections are differentiated by the value of the dimension and the Euler number of the resulting set of the whole-object intersection and differences, whereas the relations with multiple intersections are discriminated by the value of the resulting set at a coarse level and are further differentiated by the type and sequence of the whole-object intersection component in a hierarchical manner. Based on the refined topological relations, an improved method for automatic and incremental updating of the land parcel database is presented. The effectiveness of the models and algorithms was verified by the incremental update of a land cover database. The results of this study represent a new avenue for automatic spatial data handling in incremental update processes.     

Coastal pollution hazards in southern California observed by SAR imagery: stormwater plumes, wastewater plumes, and natural hydrocarbon seeps

Stormwater runoff plumes, municipal wastewater plumes, and natural hydrocarbon seeps are important pollution hazards for the heavily populated Southern California Bight (SCB). Due to their small size, dynamic and episodic nature, these hazards are difficult to sample adequately using traditional in situ oceanographic methods. Complex coastal circulation and persistent cloud cover can further complicate detection and monitoring of these hazards. We use imagery from space-borne synthetic aperture radar (SAR), complemented by field measurements, to examine these hazards in the SCB. The hazards are detectable in SAR imagery because they deposit surfactants on the sea surface, smoothing capillary and small gravity waves to produce areas of reduced backscatter compared with the surrounding ocean. We suggest that high-resolution SAR, which obtains useful data regardless of darkness or cloud cover, could be an important observational tool for assessment and monitoring of coastal marine pollution hazards in the SCB and other urbanized coastal regions.     

Dependence of the Characteristics of Solar Wind Discontinuities and Shocks with Heliolatitude and Radial Distance

The distribution of the shocks in the heliosphere and their characteristic variations are investigated using Ulysses observations. The jumps in solar wind velocity, IMF magnitude, and proton density across the shocks and discontinuities are evaluated and used to characterize them. The distribution of these discontinuities with respect to heliolatitude ± 80° and with radial distance 1 to 5 AU are analyzed during solar minimum and solar maximum to understand their global behavior. It is noticed that the jumps in solar wind parameters associated with shocks and discontinuities are more prominent during the second orbit of Ulysses, which coincided with the maximum phase of solar activity.