TABLE 1. Magnetic Susceptibilities of Selected Rocks and Minerals Rock/Mineral Chemical Formula Density Volume k Mass Z (10 3 kg m-3) (10 4 SI) (10 4 m3kg-•) References Igneous Rocks andesite basalt diabase diorite gabbro granite peridotite porphyry pyroxenite rhyolite igneous rocks average acidic igneous rocks average basic igneous rocks Sedimentary Rocks clay coal dolomite limestone red sediments sandstone shale average sedimentary rocks Metamorphic Rocks amphibolite gneiss granulite phyllite quar•ite schist serpentine slate average metamorphic rocks Non-Iron-Bearing Minerals graphite C calcite CaCOa anhydrite CaSO4 gypsum CaSO•.2H•O ice H•O orthoclase KA1Si30 s magnesite MgCO3 forsterite Mg2SiO4 serpentinite Mg3Si2Os(OH), • halite NaC1 galena PbS quarlz SiO• cassiterite Sn02 celestite SrSO• sphalerite ZnS

Results of the first detailed study of the climate proxy record in the loess-palaeosol sequence at Xining-one of the few palaeoclimate sites in the currently arid western Loess Plateau of China-illustrate the importance of making many types of rockmagnetic measurements other than susceptibility. A multiparameter approach yielded confirmation that here, as elsewhere in the Loess Plateau, the susceptibility enhancement in palaeosols was caused primarily by ultrafine magnetite and maghaemite. Nevertheless, magnetic enhancement was caused not exclusively by changes in relative grain size, but also by variations in concentration and mineralogy of the magnetic fraction.The effects of concentration variations were removed through normalization of susceptibility and anhysteretic remanence with saturation magnetization and saturation remanence, respectively. The resulting signal was ascribed more confidently to variation in magnetic grain size, which in turn was interpreted as a better proxy of pedogenesis than simple susceptibility. Variations in magnetic mineralogy were also determined to constrain interpretations further. The data were then used to discuss climate history at Xining. Finally, results from Xining were compared with other western sites and contrasted with eastern sites.In summary: (1) data is presented from a new Loess Plateau site which also appears to yield a global climate signal; (2) a demonstration is made of a more rock-magnetically robust way to separate concentration, composition and grain-size controls on susceptibility and other magnetic parameters; and (3) models are provided for inter-regional comparisons of palaeoclimate proxy records.

We propose a method based on thermal unblocking of low‐temperature saturation remanent magnetization for a quantitative estimation of the superparamagnetic [Cullity, 1972] fraction (size, d < 30 nm) of magnetite produced by pedogenesis in the Chinese loess plateau [Liu, 1988]. We applied this method to the proxy climatic records of the last 130 ka from two sites 250 km apart, but separated by the mountain range Liupan‐shan. Xifeng to the east (35.7°N, 107.6°E) and Baicaoyuan to the west (36.2°N, 105.0°E) currently have humid and arid microclimates, respectively. As expected, the superparamagnetic fraction increases during known warm temperature intervals at each site. Furthermore, the more humid site clearly has higher overall superparamagnetic fractions during most of the last 130 ka. However, during the period 5 to 10 ka ago, the relative humidity at both sites was the same within experimental errors. Bulk grain size evidence confirms the magnetic data, and we suggest that the present easterly summer monsoon in China came from a more southerly direction during this time to flow parallel to Liupan‐shan, resulting in very similar summer humidity at Xifeng and Baicaoyuan.

No abstract

Generalization of Pavlovian fear to safe stimuli resembling conditioned-danger cues (CS+) is a widely accepted conditioning correlate of clinical anxiety. Though much of the pathogenic influence of such generalization may lie in the associated avoidance, few studies have assessed maladaptive avoidance decisions associated with Pavlovian generalization. Lab-based assessments of this process, here referred to as aversive Pavlovian-instrumental covariation during generalization (APIC-G), have recently begun. The current study represents a next step in this line of work by conducting the first examination of anxiety-related dimensions of personality that may exacerbate APIC-G. Specifically, we test anxiety sensitivity (AS) and intolerance of uncertainty (IU) as moderators of relations between Pavlovian generalization and maladaptive avoidance decisions in 102 undergraduate students with wide-ranging levels of IU and AS. Results indicate a facilitative effect of AS on this APIC-G process, with AS strengthening relations between Pavlovian generalization and maladaptive generalized avoidance whether operationalizing Pavlovian generalization with psychophysiological (fear-potentiated startle) or behavioral measures. Additionally, IU was found to facilitate APIC-G when indexing Pavlovian generalization with behavioral but not fear-potentiated startle measures. Moderating effects of AS were most pronounced for stimulus classes bearing the highest resemblance to CS+, whereas effects of IU were most pronounced for the stimulus class with the highest level of threat ambiguity. Results implicate AS and IU as risk factors for the maladaptive decisional correlates of Pavlovian generalization and suggest that established associations between these traits and clinical anxiety may derive, in part, from their enhancement of maladaptive APIC-G.