Osteological features associated with ankle hyperdorsiflexion

The habitual adoption of certain gestures and postural habits can result in a variety of non‐metric traits, including supernumerary facets that are both articular and non‐articular. The squatting facet is a classical example of the former, and generally presents as a lateral articular facet on the neck of the talus that articulates with a facet on the anterior border of the distal tibia. These facets arise owing to the adoption of the squatting position and the hyperdorsiflexed position of the ankle joint, bringing the talus and tibia into immediate approximation. This study reports on the difference between the classical squatting facet and a non‐articular facet, which can also present on the neck of the talus but occurs, probably, as a result of soft tissue pressure, rather than bony articulation. It is suggested that whilst the function of the two facets may be similar, their aetiology is likely to be very different. Copyright © 2001 John Wiley & Sons, Ltd.     

Source movements associated with IPDP pulsations

Information on the temporal movement in the source of IPDP (intervals of pulsations of diminishing period) have been obtained by applying time delay location techniques to two events recorded at three stations in Southeast Australia. It is found that IPDP events propagate from coherent finite high latitude source regions to middle and low latitudes in the ionospheric duct. A westward drift in the source location in the early evening hours is observed as the IPDP frequency increases with time. This is attributed to the energization of ~50 keV substorm associated protons as they drift azimuthally and move to lower L-values under the influence of electric field convection.     

Atmospheric transparency variations associated with geomagnetic disturbances

Geomagnetic storm-time variations of the atmospheric transparency in various latitudinal regions are considered. It is shown that the solar radiation measured at the Earth's surface at local noon increases by approximately 0.1 cal/cm² min at latitudes ϑ = 60–70° during geomagnetic disturbances. At middle latitudes (ϑ≈ 50°) this effect is not observed. The variation of the atmospheric transparency is shown to be associated with a simultaneous decrease of the galactic cosmic ray intensity.     

Small-scale ionospheric structures associated with mid-latitude spread-F

Slant-F traces on ionograms recorded by a modern ionosonde in a sunspot-minimum period have revealed the existence of field-aligned irregularities at times of spread-F occurrence. This appears to be the first investigation in a mid-latitude region around 36° (geomagnetic) to detect these irregularities at F₂-region heights using an ionosonde. Although such traces were observed frequently near sunspot minimum they were seldom recorded for periods close to sunspot maximum. Also, for a specific spread-F event in August 1989, both the ionograms from the modern ionosonde and scintillations of 150 MHz transmissions from a Transit satellite indicate the existence in the ionosphere of periodic structures (period around 11 min). The scintillation recording also included rapidly fading signals indicative of small-scale structures. The satellite had a path close to the magnetic meridian which passed through the recording station (Brisbane, Australia). Because of the enhanced signal fluctuations in the scintillation recording on this occasion it seems likely (with the support of other evidence on the ionograms) that the small-scale structures present were field-aligned.     

X光照相技术在文物及考古学研究中的应用

X光照相方法的无损特性,就决定了这一技术适合被用于研究物这一特殊对象。本通过具体实例介绍了X光照相技术在物及考古学研究中的应用：可以反映不同材质物的保存状况,揭示被锈蚀物覆盖的铭及纹饰,显示古代器物的工艺痕迹,有助于考古出土物线图的绘制等。     

Microscopical findings associated with the diagnosis of osteoporosis in palaeopathology

This paper presents some preliminary results on microscopical identification of microfractures in human skeletal remains which may be associated with osteoporosis. A technique is described for the examination of cancellous bone and applied to a number of vertebrae and one radius. All the material used is Romano-British or English medieval. However, microscopical screening for osteoporosis could form a useful part of comparative studies on historically or geographically different populations. The archaeological significance of osteoporosis in terms of skeletal ageing and nutritional status is discussed.     

Grossly-distorted isoionic contours associated with spread-F occurrence at mid-latitudes

A directional ionosonde has been used to investigate a mid-latitude travelling ionospheric disturbance which passed over Brisbane, Australia, on the night of 31 July/1 August 1981. The analyses have revealed what appears to be a large-scale frontal height rise (about 300 km wide) travelling in a north-west direction with a speed of 93 ms⁻¹. Smaller-scale frontal structures with wavelengths of some tens of kilometres appeared near the crest of this large-scale upwelling and have the same frontal orientations. These are responsible for the spread-F seen on ionograms during the passage of the disturbance. Also, associated with the disturbance was a tongue of ionization which extended down from the crest of the upwelling more than 100 km. It appeared to be drifting with the same speed and in the same direction as the upwelling. Near the lowest extremity of the tongue the ionization density was at least 35% greater than elsewhere in the ionosphere. The lowest extremity of the tongue was located 240 km from the recording station as the large-scale frontal structure passed overhead. Statistical analyses using 19 tongue events in 1979 have shown that ionospheric height rises seem to be generally associated with these events not only at the recording station, but also in the conjugate hemisphere. Certain characteristics of the mid-latitude disturbance which have been investigated in this paper are compared with the characteristics of similar disturbances in equatorial regions.     

Faraday polarization fluctuations associated with amplitude scintillations at Lunping

The diurnal, seasonal and solar cycle variations of Faraday polarization fluctuations (FPF) associated with amplitude scintillations observed at Lunping, Taiwan (25.0°N, 121.2°E : geographic) during the period 1978–1981 are presented. The occurrence of polarization fluctuations is maximum in the premidnight hours. FPFs occur either simultaneously or with a time lag after the onset of amplitude scintillations. There is an increase in FPF activity with an increase in sunspot activity. Occurrence of FPF peaks in the equinoxes. There had been a moderate activity in summer while the winter occurrence is a minimum. The seasonal occurrence pattern compared with reports from other locations indicates a longitudinal control on FPF activity. The maximum probable duration of FPF ranges from 15 to 30 min. It was found that the association of FPF with range spread-F is much better than that with frequency spread-F. Large ambient ionization densities corresponding to plasma frequencies greater than 15 MHz appear to create a favourable environment for the occurrence of FPF.     

Intensity of tropospheric circulation associated with solar magnetic sector boundary transits

The fractional decrease in the vorticity area index associated with transits past the Earth of interplanetary magnetic sector boundaries increases as the value of vorticity used to compute the index increases. This suggests that after the boundary transit there is an approximately uniform reduction in all the values of vorticity that are ≥20 × 10⁻⁵s⁻¹. In low latitudes and large absolute vorticities (≥ 30 × 10⁻⁵s⁻¹) the average change in the vorticity area index approaches 50%.     

Hydrothermal activity associated with the Ries impact event, Germany

Combined field studies, optical and scanning electron microscopy, and electron microprobe studies of impactites from the Ries impact structure, Germany, have allowed a clearer picture of the hydrothermal system associated with the Ries impact event to be made. Hydrothermal alteration is concentrated within impact‐generated suevites in the interior of the crater (crater suevites) and around the periphery (surficial suevites), with minor alteration in the overlying sedimentary crater‐fill deposits. The major heat source for the Ries hydrothermal system was the suevite units themselves. Hydrothermal alteration of crater‐fill suevites is pervasive in nature and comprises several distinct alteration phases that vary with depth. An early phase of K‐metasomatism accompanied by minor albitization of crystalline basement clasts and minor chloritization, was followed by pervasive intermediate argillic alteration (predominantly montmorillonite, saponite, and illite) and zeolitization (predominantly analcite, erionite, and clinoptilolite). Hydrothermal fluids were typically weakly alkaline during the main stage of alteration. In contrast to the crater‐fill suevites, alteration within surficial suevites was typically restricted to montmorillonite and phillipsite deposition within cavities and fractures. The pervasive nature of the alteration within the crater‐fill suevites was likely due to the presence of an overlying crater lake; whereas alteration within surficial suevites typically occurred under undersaturated conditions with the main source of water being from precipitation. There are exceptional outcrops of more pervasively altered surficial suevites, which can be explained as locations where water pooled for longer periods of time. Hydrothermal fluids were likely a combination of meteoric waters that percolated down from the overlying crater lake and groundwaters that flowed in from the surrounding country rocks.     

A study of ground diffraction pattern parameters associated with D-region partial reflections

D-region drift observations have been made at Adelaide in recent years using the three-receiver technique. The amplitude fading records are analysed by a method known as ‘full correlation analysis.’ The resultant drift values have been reported elsewhere. However, in the process of correlation analysis several other parameters related to the geometry and variability of the ground diffraction pattern are defined and calculated.These parameters often fluctuate markedly from one record to the next but on the average they show consistent changes with height, time of day and with season. These variations, and some aspects of the physical interpretation of the parameters themselves are discussed.     

Mid-latitude rocket measurements op plasma irregularities associated with topside density depletion

A plasma irregularities spectrum analyzer and a Langmuir probe experiment on a rocket experiment conducted at mid-latitudes during quiet night-time winter conditions revealed the existence of an isolated plasma density depletion between 700 and 1100 km. A substantial enhancement of intensity of the irregularities coinciding with the depletion was observed over a broad band of irregularity sizes ranging from tens of meters to several kilometers. The power spectral index was equal 0.84∓0.17 as compared to 1.71∓0.56 for the irregularities outside the plasma depletion.     

Large amplitude quasi-periodic fluctuations associated with a mid-latitude sporadic E layer

For the first time a sounding rocket has been launched into a mid-latitude sporadic E event which was shown to be the source of VHF radar echoes. The layer had a very high peak electron density (∼10⁶ cm⁻³) and was thicker (∼5 km) than most events previously studied by rockets and incoherent scatter radars. The layer was modulated in a remarkable quasi-periodic manner which has not been reported earlier. Twenty cycles of these structures were detected and they seem to be oriented horizontally rather than vertically with periods in the rocket frame in the rage 6–10 s. There is also some evidence that the modulation was detected below as well as above the peak in the electron density, although the bulk of the flight was above the peak. Although the VHF radar echoes were decaying at the time and place where the rocket traversed the E layer, one burst of high amplitude short wavelength fluctuations was detected by the space-borne instruments and had a power spectrum similar to that of a secondary gradient drift mode. This burst occurred at the peak of one of the periodic electron density fluctuations. We discuss two possible sources for the dominant fluctuations: large-scale gradient drift waves and atmospheric acoustic waves. The latter seem most consistent with the data.     

Mid-latitude ionospheric scintillations of VHF radio signals associated with peculiar fluctuations of Faraday rotation

Simultaneous measurements of the scintillation and Faraday rotation of 136 MHz radio waves radiated by the Japanese geostationary satellite ETS-2 have been studied at Kokubunji Japan during April to May, 1977.These preliminary results show that there is a close association between scintillations and the peculiar fluctuations of the Faraday rotation due to ionospheric spread F, and an empirical formula relating them is presented.Furthermore, the successive daily values of the two parameters show a close correspondence with a cross correlation coefficient of about 0.8. An unexpected result is that cross-correlation between the incidence of Es and the Faraday fluctuations on a daily bases is found to be about 0.65.     

Sources and composition of fluids associated with fluorite deposits of Asturias (N Spain)

The fluorite deposits of Asturias (northern Iberian Peninsula) are hosted by rocks of Permo‐Triassic and Palaeozoic age. Fluid inclusions in ore and gangue minerals show homogenization temperatures from 80 to 170°C and the presence of two types of fluids: an H₂O–NaCl low‐salinity fluid (<8 eq. wt% NaCl) and an H₂O–NaCl–CaCl₂ fluid (7–13 wt% NaCl and 11–14 wt% CaCl₂). The low salinity and the Cl/Br and Na/Br ratios (Cl/Br_molar 100–700 and Na/Br_molar 20–700) are consistent with an evaporated sea water origin of this fluid. The other end‐member of the mixture was highly saline brine with high Cl/Br and Na/Br ratios (Cl/Br_molar 700–13 000 and Na/Br_molar 700–11 000) generated after dissolution of Triassic age evaporites. LA‐ICP‐MS analyses of fluid inclusions in fluorite reveal higher Zn, Pb and Ba contents in the high‐salinity fluids (160–500, 90–170, 320–480 p.p.m. respectively) than in the low‐salinity fluid (75–230, 25–150 and 100–300 p.p.m. respectively). The metal content of the fluids appears to decrease from E to W, from Berbes to La Collada and to Villabona. The source of F is probably related to leaching of volcanic rocks of Permian age. Brines circulated along faults into the Palaeozoic basement. Evaporated sea water was present in permeable rocks and faults along or above the unconformity between the Permo‐Triassic sediments and the Palaeozoic basement. Mineralization formed when the deep brines mixed with the surficial fluids in carbonates, breccias and fractures resulting in the formation of veins and stratabound bodies of fluorite, barite, calcite, dolomite and quartz and minor amounts of sulphides. Fluid movement and mineralization occurred between Late Triassic and Late Jurassic times, probably associated with rifting events related to the opening of the Atlantic Ocean. This model is also consistent with the geodynamic setting of other fluorite‐rich districts in Europe.     

Temporal changes in Arikara humeral and femoral cross-sectional geometry associated with horticultural intensification

Humeral and femoral cross-sectional properties from three archaeological variants of the Arikara, an American Great Plains Indian tribe, were analyzed for temporal (16th to 19th centuries) changes in long bone architecture, asymmetry, and sexual dimorphism associated with intensification of horticulture during the late protohistoric and early historic periods. There were a number of significant changes in long bone, especially femoral, cross-sectional morphology and asymmetry among females through time that probably reflect increases in the workload necessary to produce surplus crops. Changes in long bone architecture among males are restricted to the humerus and may reflect a greater reliance on firearms. The pattern of sexual dimorphism also changes through time among the Arikara due to a combination of environmental (nutrition and disease) and mechanical factors.     

Red calcite: an indicator of paleo‐karst systems associated with bauxitic unconformities

A unique red calcite generation, which fills fractures/cavities, is hosted by Mesozoic carbonates in the Transdanubian Range, Hungary. Solid inclusions are located along growth zones of calcite. Hematite, the most abundant solid inclusion, gives the red colour of it. Outcrop‐scale geometry, mineralogical features and detrital mineral assemblage (hematite, gibbsite, goethite, kaolinite, smectite, illite, Cr‐spinel, monazite, xenotime, zircon, apatite and Ti‐oxide) of calcite precipitates suggest strong correlation between the calcite and nearby karst bauxite deposits. Fluid inclusion petrography and microthermometry (T < 50°C; salinity from 0 to 0.17 NaCl eq. w%) of primary fluid inclusions, and the stable isotope trend of the calcite, following the meteoric water line, clearly indicate vadose and phreatic meteoric origin in a near‐surface karst system. The late Cretaceous to mid‐Eocene unconformity‐related cavity‐filling deposits occur close to the surface; indicating that the most recent Quaternary exhumation re‐exposed those surfaces that existed at the time of calcite mineralization. Thus, red calcite precipitates are interpreted as being speleothems, vestiges of the subterranean part of the pre‐Middle Eocene karst. The infiltrated, fine bauxite particles enclosed by the calcite are the witnesses of the once areally extensive pre‐Middle Eocene bauxitic blanket that became partially eroded by the time of the deposition of the cover beds. Red calcite when found in core samples may provide good evidence on bauxite formation associated with the overlying unconformity, even if it was later removed by erosion. Therefore, presence or absence of red calcite may be used as distinguishing criteria between karst episodes with or without bauxite formation.