Sympathetic Variation Research Articles

Autonomic impairment in rheumatoid arthritis

To determine if there is a difference between autonomic cardiac control as measured by heart rate variability (HRV) in women with rheumatoid arthritis (RA) compared to a healthy control group. The RA group (45) and control group (39) were matched for age and body mass index (BMI). Three techniques were used: time domain, frequency domain and Poincarè plot analysis. All possible confounding factors were excluded and the test environment strictly regulated. Basal heart rate was significantly higher in the RA patients. In the supine position significant differences existed between RA patients and controls (P ≤ 0.01). Indicators of parasympathetic activity showed significantly lower variation in the RA group (root mean square of the standard deviation [RMSSD] = 14.70, percentage of successive normal-to-normal interval differences larger than 50 ms [pNN50] = 0.50, standard deviation [SD]1 = 10.50, high frequency [HF] (ms(2)) = 31) compared to controls (RMSSD = 29.40, pNN50 = 7.8, SD1 = 20.9, HF (ms(2)) = 141.00). Indicators of sympathetic variation were also significantly lower in RA patients (SD2 = 36.70, low frequency [LF] (ms(2)) = 65) compared to controls (SD2 = 49.50, LF (ms(2)) = 175). In the standing position eight variables indicated autonomic impairment by significant differences (P ≤ 0.01) between the groups. The response of the RA group to an orthostatic stressor showed less vagal withdrawal, (P-values for RMSSD = 0.038, pNN50 = 0.022, SD1 = 0.043 and HF [ms(2) ] = 0.008 respectively); and lower sympathetic response (P-values for SD2 = 0.001 and LF [ms(2) ] < 0.001) when compared to controls. An inability of the autonomic nervous system to efficiently compensate for internal and external environmental changes may predispose RA patients to arrhythmias, thereby increasing cardiovascular mortality. All three methods used showed the same outcome, implying decreased HRV and thus an increased risk for arrhythmias in RA patients. Evaluating the autonomic nervous system might be critical in planning management of RA patients.

Anglo-Saxon animal husbandry techniques revealed though isotope and chemical variations in cattle teeth

The Sr concentration and isotope composition of tooth enamel from domesticated animals from two neighbouring Anglo-Saxon settlements, at Empingham (6–7th century) and Ketton (10–12th century) in Rutland, central England, are compared both with each other, and with associated human populations. Data from the Empingham II site form discrete fields in Sr concentration and isotope composition space for cattle, pig and sheep with a partial overlap of the human and pig fields. By contrast there is significant overlap in all the animal and human data fields from the Ketton site. The differences in data distribution between the two sites are attributed to animal husbandry techniques, as the surface geology of the two areas is very similar, implying geological factors are an unlikely cause of the difference. It is suggested that the grazing and feeding patterns of animals at the Empingham II site were controlled and restricted, whereas at the Ketton site the animals grazed and foraged freely over a common area. Strontium isotope variation within cattle molars from the two settlements show marked differences that reflect the nature of their feeding and rearing. The enamel from a cattle molar from the Empingham II site has a well-defined, systematic variation of Sr isotope composition with Sr concentration, whereas no such patterns exist in a comparable cattle molar from Ketton. Chemical and O isotope variations in the cattle tooth from Empingham II show sympathetic variation of Sr and Ba concentrations with Sr isotope composition from cusp to cervix. The cusp has higher Sr and Ba concentrations log (Sr/Ca) ratio of −3.1 and 87Sr/ 86Sr ratio of 0.71151 where as the cervical region of the enamel has log (Sr/Ca) = −3.3 and 87Sr/ 86Sr = 0.71061.

Seasonal records of climatic change in annually laminated tufas: short review and future prospects

AbstractMany Recent and fossil freshwater tufa stromatolites contain millimetre‐scale, alternating laminae of dense micrite and more porous or sparry crystalline calcites. These alternating laminae have been interpreted to represent seasonally controlled differences in the biotic activity of microbes, and/or seasonally controlled changes in the rate of calcification. Either way, couplets of these microbially mediated alternating calcified laminae are generally agreed to represent annual seasonality. Combined stable isotope (δ18O and δ13C) and trace element (Mg, Sr, Ba) geochemistry from Recent tufa stromatolites show that seasonal climatic information is available from these calcites. Variability in δ18O (and in one case Mg concentration) has been shown to be controlled primarily by stream temperature change, usually driven by solar insolation. In arid climates, seasonal evaporation can also cause δ18O enrichment by at least 1‰. Variability in δ13C results potentially from: (1) seasonal change in plant uptake of 12C‐enriched CO2; (2) seasonal change in degassing of 12C‐enriched CO2 in the aquifer system; and (3) precipitation of calcite along the aquifer or river flow path, a process that increases δ13C of dissolved inorganic carbon (DIC) in the remaining water. Mechanisms 2 and 3 are linked because calcite precipitates in aquifers where degassing occurs, e.g. air pockets. The latter mechanism for δ13C enrichment has also been shown to cause sympathetic variation between trace element/Ca ratios and δ13C because trace elements with partition coefficients much greater than 1 (e.g. Sr, Ba) remain preferentially in solution. Since degassing in air pockets will be enhanced during decreased recharge when water saturation of the aquifer is lowest, sympathetic variation in trace element/Ca ratios and δ13C is a possible index of recharge and therefore precipitation intensity.High‐resolution geochemical data from well‐dated tufa stromatolites have great potential for Quaternary palaeoclimate reconstructions, possibly allowing recovery of annual seasonal climatic information including water temperature variation and change in rainfall intensity. However, careful consideration of diagenetic effects, particularly aggrading neomorphism, needs to be the next step. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Rock magnetic characterization of pedogenesis under high energy depositional conditions: A case study from the Mio–Pliocene Siwalik fluvial sequence near Dehra Dun, NW Himalaya, India

Systematic rock magnetic studies accompanied by field investigations are presented for 51 pedogenic horizons from magnetostratigraphically constrained Middle–Upper Siwalik fluvial sequence (∼ 9–4 Ma) near Dehra Dun in the Himalayan Foreland Basin (HFB). Detailed sedimentologic studies infer predominantly proximal to distal alluvial fan setting with considerably high rate of sedimentation (> 55 cm/ka). Paleosol profiles in the Mohand Rao (MR) section are commonly truncated by channel activity. These paleosols display few rootlets, diffused color contrast amongst variegated pedogenic horizons, rare concretions, intense gleying at places, and frequent incursions by sand/silt layers (< 30 cm) characterizing their vicinity to channel. The mean mass specific magnetic susceptibility ( χ lf) for pedogenic horizons is ∼ 0.95 × 10 − 8 m 3/kg (Max = 1.4 × 10 − 8 m 3/kg; Min = 0.5 × 10 − 8 m 3/kg) and the associated non-pedogenic layers is ∼ 0.82 × 10 − 8 m 3/kg (Max = 1.2×10 − 8 m 3/kg; Min = 0.4 × 10 − 8 m 3/kg). The low frequency dependence of the susceptibility ( χ fd mean = 2%) and high coercivities ( B OCR mean = 425 mT) of the pedogenic layers infer the absence of finer pedogenic superparamagnetic (SP) fraction that might have depleted during post depositional burial processes. Acquisition of isothermal remanent magnetization (IRM) shows under-saturation and gentle upward trend even at high applied fields (4000 mT) advocating the predominance of hematite and goethite. Sympathetic variation in the total organic and inorganic carbon content with iron oxides stable under warm humid, oxidative arid and cold restricted conditions confirm the sensitivity of the rock magnetic parameters to ambient climatic condition. Relative variations in goethite, hematite and ferrimagnetic contents have been derived from ratios mainly based upon selective IRM saturations and their coercivities. These studies are validated by sandstone petrography and clay mineralogy for the same section. However, the variation in rock magnetic parameters shows a better amplification and allows relative quantification of the ambient climatic conditions. The assemblage of iron oxides using the rock magnetic ratios of the pedogenic layers in these high energy conditions broadly infer the prevalence of semi-humid to semi-arid climate entirely during the Late Miocene to Early Pliocene period in the HFB with an increased seasonality during early Pliocene. The present approach envisages a great scope for quantitative database under the given setup of high energy conditions that are common in the Mio–Pliocene HFB.

Polymetamorphism and isobaric cooling of pelitic schists from the Annex sulphide deposit, Gordonia Belt, South Africa

Abstract Muscovite‐poor pelitic schists in the wallrocks of the Proterozoic Annex sulphide deposit, near Prieska, South Africa, contain peak metamorphic assemblages including Crd + Bt + Sil, St + Sil + Bt, Crd + St + Bt and, rarely, Ky + St ° Crd. All rocks include oligoclase, quartz and commonly Fe–Mn garnet, with or without muscovite. Peak assemblages, assigned to M2 regional metamorphism in the Gordonia Belt (Namaqua Province), are syn‐ to post‐kinematic with respect to the main S2 fabric although larger staurolite grains contain S1 inclusion trails. Garnet–biotite thermometry, utilizing corrections for Fe3+, Mn, AlVI and Ti, yields peak temperatures of 571–624°C at pressures of 4.5–6.0 kbar. Consideration of the sympathetic variation of XMn in garnet with XMg in biotite and the preserved zoning patterns in prograde garnets, together with the inferred prograde transition from kyanite to sillimanite, indicates that heating occurred during mild decompression to the M2 metamorphic peak. Sillimanite and cordierite grew last in the prograde sequence, possibly related to a pulse of thermal metamorphism (M3) that is found along the margin of the Keimoes Suite batholith to the north.Retrograde assemblages, including Ms + Ky + Chl + Qtz (after Crd + Bt), Ky + Ms (after Sil) and Chl + Ms (after St) indicate a period of isobaric cooling (M4a) terminated by rehydration in the kyanite stability field at about 500°C.The size difference between prograde (1–2‐mm) and retrograde (0.05–0.1‐mm) mineral grains indicates substantial undercooling below equilibrium positions of relevant retrograde reactions prior to rehydration, and explains why cordierite that grew during M2 is almost completely destroyed. Post‐M4a regrowth of staurolite and garnet (M4b) is spatially linked to sites of M4a rehydration. It reached temperatures of 510–530°C, remaining within the stability field of kyanite.A best fit of the observed textural history to the Namaqua orogenic cycle involves collision and heating (M2/D2) followed by granite intrusion (M3), rifting (M4a) and renewed heating due to crustal loading during volcanism (M4b). The P–T path for the Annex region is consistent with those derived from elsewhere in the Gordonia Belt and, with modification, to that published already for the nearby Prieska Copper Mines.

Isotopic chronometry of zoned garnets: growth kinetics and metamorphic histories

Basic information on the chronological and pressure-temperature evolution of regional metamorphic terrains may in principle be derived from metamorphic garnets because of the similarly low diffusivities of Sm, Nd and major cations in this mineral. We report here Sm Nd and Rb Sr isotopic and major element data on prograde garnets from regionally metamorphosed pelites from Newfoundland. The garnets preserve a prograde major element zonation as well as a sympathetic variation in Sm/Nd ratio. Sm Nd data for separated portions of the garnet from core to rim provide both upper limits on the time for garnet growth and demonstrate synchronous growth of different garnet grains on a hand specimen scale. The Rb Sr data on the same garnet fractions are in general agreement with these results but in some cases cannot be interpreted in terms of growth. A minimum heating rate of 3K Ma −1 is derived by combining the estimates for garnet growth time with the apparent temperature interval over which the garnet grew, deduced from the major element zonation. This value is similar to the minimum suggested by theoretical models for the thermal evolution of thickened continental crust. The growth rate is within the range of 1.3–19 mm Ma −1, set respectively by the isotopic data and the likely upper limit for heating rate during regional metamorphism. These growth rates appear too slow to be controlled by surface reaction and suggest that other factors, such as transport, may be rate-limiting. In this case, the limits set on the effective diffusion coefficient for material transport to the growth site ( = 0.4–6.1 × 10 −17 m 2 s −1) suggest that grain boundary diffusion is probably the transport mechanism for supply of material to the growing garnet.

Fluctuations in surface height of active lava lakes during 1972–1974 Mauna Ulu Eruption, Kilauea Volcano, Hawaii

An “active” lava lake is one that forms directly on top of a magma column, as opposed to an “inactive” one formed by passive ponding of lava within a preexisting crater. Two active lava lakes operating within summit craters of newly constructed volcanic shields at Mauna Ulu and Alae were the longest‐lived of any observed in a Hawaiian rift zone to date. Small‐scale fluctuations (a few to 20 m) in the height of lake surfaces are typically associated with degassing (“gas piston”) activity. Larger fluctuations, as great as 200 m, reflect major changes in eruptive activity. Measurements of surface height fluctuations of Mauna Ulu lake show gross positive correlation with variation in summit tilt, which in turn reflects the inflation‐deflation state of Kilauea's summit magma reservoir. A more tenuous conclusion is that a sympathetic variation possibly exists between surface heights of the Mauna Ulu and Alae lakes. Collectively, these observations (1) require the existence of a fully engorged, connected, open, and hydraulically efficient magma conduit system linking the summit reservoir with the lava lakes, (2) provide additional evidence for the postulated regime of “quasi‐steady‐state” magma transfer that characterized much of the eruption, (3) imply that fluctuations in lake surface reflect variation in magma supply rate to the reservoir and/or outflow rate from the Mauna Ulu‐Alae vents, and (4) suggest undetected episodes of magma intrusion or storage in Kilauea's east rift zone during 1973.

Trace and platinum-group element geochemistry and the development of the Merensky unit of the Western Bushveld complex

Whole-rock samples of the Merensky Unit were analysed for major elements, Cu, Ni, Cr, Co, Eu, Th, U, Cs, and the platinum-group elements Pt, Pd, Rh, Ir and Au. There is a sympathetic variation of Cu, Ni, Co, and S throughout the sequence. Th and U abundances are highest around the Merensky Reef, and their distribution in the rest of the unit reflects the amount of mesostasis. Eu distribution is governed by primary plagioclase. Pt, Pd, Rh, Ir and Au (PM) are concentrated in the Merensky Reef. The relative proportions throughout the unit are Ir<Rh<Pd⪕Au<Pt. Au, Pd, Pt are depleted upwards in the plagioclase-rich part of the unit. Except for Ir, the PM correlate with Th and U at lower PM levels. The PM are highly intercorrelated and there is considerable variation in the individual ratios. The distribution of trace elements in the Merensky Unit was governed by the growth rates of the primary silicates. At low abundances the PM behave as incompatible elements, together with late S. At higher concentrations the primary S content controls PM abundances. Residual liquid compositions computed from a marginal-facies analysis show parallel FeO and SiO2 enrichment trends; interaction of these trends resulted in the Merensky Reef and its attendant mineralization.

Al/Cr ratios of coexisting pyroxenes and spinellids in some ultramafic rocks

Al/Cr atomic ratios of coexisting spinellids and ortho- and clinopyroxenes show a pattern of sympathetic variation that persists through ultramafic rocks of layered mafic complexes of upper-crustal type, Alpine complexes, and the nodules found in kimberlites and alkaline basalts. Simple expressions are empirically derived to link (Al/Cr) orthopyroxene and (Al/Cr) spinel ratios in putatively equilibrated rocks. Equivalence of spinel compositions in shallow layered complexes and kimberlite nodules of deep-seated origin negates direct crystallochemical control of Al/Cr ratios of spinels by pressure. The application of various pyroxene geothermometers evinces no correlation between (Al/Cr) spinel ratios and temperature. Whereas high-Al spinels characterize simple four-phase (olivine—orthopyroxene—clinopyroxene—spinel) peridotites, low-Al spinels typify peridotites with other aluminous phases (garnet, amphibole, mica or plagioclase). The rôle of pressure in determining spinel compositions is therefore indirect, insofar as it controls the stability of other phases into which Al is partitioned.

Chemical composition of Martian fines

Of the 21 samples acquired for the Viking X ray fluorescence spectrometer, 17 were analyzed to high precision. Compared to typical terrestrial continental soils and lunar mare fines, the Martian fines are lower in Al, higher in Fe, and much higher in S and Cl concentrations. Protected fines at the two lander sites are almost indistinguishable, but concentration of the element S is somewhat higher at Utopia. Duricrust fragments, successfully acquired only at the Chryse site, invariably contained about 50% higher S than fines. No elements correlate positively with S, except Cl and possibly Mg. A sympathetic variation is found among the triad Si, Al, Ca; positive correlation occurs between Ti and Fe. Sample variabilities are as great within a few meters as between lander locations (4500 km apart), implying the existence of a universal Martian regolith component of constant average composition. The nature of the source materials for the regolith fines must be mafic to ultramafic.

An Archean ultramafic turbidite from Lac Guyer, James Bay Area, Quebec, Canada

A sedimentary rock of ultrabasic composition (MgO 28%, SiO2 48%) has been identified in an Archean volcanic sequence ranging from basaltic to peridotitic komatiite in composition, in the Lac Guyer greenstone belt, James Bay region of New Quebec. The ultramafic sedimentary rock is cyclically layered with an internal stratigraphy indicative of deposition from an aqueous turbidity current. Layers which are interpreted to correlate with the arenaceous A, B, and C divisions of turbidites are pyroxene-rich and display sedimentary features such as grading, parallel and cross-laminations, and climbing ripples. Foliated layers with higher normative olivine contents preserve loading and soft sediment deformation structures indicating a pelitic nature when deposited and are interpreted as Bouma E divisions. These features combined with a sympathetic variation of Al2O3 with normative olivine content in successive Bouma divisions suggest that a Mg-chlorite with subordinate serpentine rather than olivine was present, together with pyroxenes and opaques, in the initial sediment. This sediment may have been derived from the degradation of the associated komatiitic volcanics or may represent a contemporaneous reworked ultramafic tuff or ash flow.

Fabric development in a quartz-feldspar mylonite

Variations in quartz c-axis fabrics in a mylonite hand specimen correlate with variations of microstructure. Large feldspar clasts in the quartz-rich groundmass have caused heterogeneous deformation on the microscale and different deformation paths undergone by the different regions are postulated to have caused the variations in c-axis fabrics. The different microstructures found in the regions are believed to be related to sympathetic variation in strain rate and the degree of local strain heterogeneity. The microstructures reflect a combination of dynamic recovery and dynamic recrystallization processes. Although the importance of these processes is acknowledged it is thought that fabrics have developed in relation to the deformation process, rather than from the effects of recrystallization modifying pre-existing or co-developing deformation fabrics. Although diffusional processes were important, deformation may have taken place primarily as the result of the conservative component of dislocation motion within the subgrain interiors. Simulations of fabric development were attempted using a program based on the Taylor—Bishop—Hill analysis. The observed asymmetric c-axis fabrics could arise in several ways. Only the implications of two-stage histories are explored in these simulations. It is suggested that fabrics develop in relation to the kinematic framework and that the orientation of the elements of a pattern of preferred orientation are sensitive to the last stages of deformation. Observations from the mylonite strongly support the idea of a late stage comparatively homogeneous deformation that has imprinted itself on the developed fabrics.

Electron-probe microanalysis and geothermometry of sphalerite in the ingaladhal sulphide lode, chitradurga district, mysore state

Sphalerites coexisting with pyrrhotite and pyrite in Ingaladhal lode, Chitradurga District, Mysore State, were analysed for Fe, Mn, Cd, and S contents using an electron probe microanalyser. Four among the above samples were also analysed by X-ray diffraction using Cu-Kα radiation. Unit cell dimensions of sphalerites were calculated using Skinner’s equation. The iron content of sphalerite shows sympathetic variation with its temperature of formation. The estimated temperatures of formation of sphalerite, using Kullerud’s curve ranges between 340° C.–460° C. From the temperature measurements it is concluded that the ore body was formed at a single period of crystallization and that it would continue at depth.

Rare-earth elements in the Skaergaard intrusion

The chilled marginal gabbro of the Skaergaard intrusion, East Greenland, is very similar in absolute and relative rare-earth abundances to other gabbros that have been studied. The rocks from the layered series that were analyzed all had rare-earth contents similar to that of the chilled gabbro, except for the specimen from the very top of the series, which was enriched more than ten times. The rare earths appear to have become increasingly concentrated in the magma as solidification progressed, but there was little change in relative abundances. No quantitative sympathetic variation between the rare earths and any major element was observed. Some minor fluctuations in rare-earth abundances appear to be correlated with variations in feldspar contents of the intrusion. It does not appear to be possible to explain the partition of the rare earths by the logarithmic theory.

Variation of strontium isotopes in tektites

The rubidium, strontium, and strontium isotopic compositions have been determined in tektites from Indo-China, Philippine Islands, Java, Australia, Texas, Georgia, Massachusetts and Czechoslovakia. The range of Sr 87 Sr 86 ratios in 18 tektites is from 0.7121 to 0.7223, indicating the results of Pinson et al. (1958), reporting no radiogenic strontium in tektites, were not of sufficient precision to study the problem definitively. This range of Sr 87 Sr 86 ratios is quite small compared to the range found in nature, in general agreement with previous studies of oxygen and silicon isotopes in tektites. Rb and Sr contents of tektites from a given locality are very similar, but differences exist between localities. There is indicated, however, a sympathetic variation of the Sr 87 Sr 86 and Rb Sr ratios, i.e. the tektite groups have age values of approximately 400 m.y. If tektites were derived from the Moon, and the surface of the Moon is old (4.5 b.y.), the observed Sr 87 Sr 86 ratios could not have been developed by achondritic, granitic, or tektitic surface material, but could have been generated by a basaltic type material. However, production of tektites from a basaltic type surface material during a high temperature fusion implies extreme fractionation in a direction contrary to expectation. A second possibility is that the Moon has undergone differentiation within the last 500 m.y.

The Significance of Variations in the Strontium Content of Deep Sea Cores

An Atlantic equatorial eupelagic core, Lamont A180‐76, was systematically analyzed for strontium and calcium at 10‐cm intervals down the core. The globigerina contribution to the core was found to contain essentially a constant strontium‐to‐calcium ratio independent of depth in the core. When the globigerina contribution to the strontium and calcium contents of the core are subtracted, a variation in the strontium‐to‐calcium ratio for the fine fraction is observed which is related to the Ericson temperature curve for the core—the high strontium‐to‐calcium ratio corresponding to a time of high surface ocean temperature. It is postulated that this sympathetic variation is best explained as the representation of the relative abundance of celestite tests secreted by an acantharian radiolaria. If the carbonate and lutite sedimentation rates are sensibly constant, then Acantharia productivity is temperature dependent. On the other hand, recent work has shown that the rate of sedimentation in the Atlantic equatorial region during the last glacial period was twice as high as the present rate. Since the strontium‐to‐calcium ratio of the fine fraction is roughly half as great for glacial time relative to recent times, this may be interpreted as the expression of a constant rate of celestite deposition.

Lead and the Final Product of Thorium

IT is now practically certain that the final product of the uranium family of radio-elements is isotopic, or chemically identical, with lead. The constancy of the ratio between lead and uranium, Pb/U, in the case of primary rock-forming minerals of the same geological age, and its sympathetic variation in the case of minerals of different ages, go far to establish this important conclusion. The recent discovery that all the final products of radio-active disintegration fall into Group iv. B of the periodic classification has naturally led to the further suggestion that each one is isotopic with lead.