Contemporaneous Decrease Research Articles

Ichnology of a marine regressive systems tract: the Middle Triassic of Svalbard

The Middle Triassic succession of Svalbard forms a pronounced second-order transgressive–regressive sequence. This is represented by deltaic sediments in western Spitsbergen, grading to deep restricted shelf deposits in central and eastern parts of the archipelago. Nine ichnogenera have been recognized, which form three local ichnofacies or trace fossil assemblages: a Thalassinoides assemblage that is dominant in low-energy shelf settings, a Taenidium– Rhizocorallium assemblage that occurs in intermediate-energy deltaic and shelf environments, and a Polykladichnus assemblage that dominates high-energy deltaic environments. These three trace fossil assemblages overlap, both as a result of fluctuations in energy level with time and because of differential preservation of the different tiers. The main control of the distribution of the assemblages is an upwards increase in energy regime during progradation of the deltaic sediments along western Spitsbergen, and a contemporaneous decrease in energy regime more distally. The succession has also experienced fluctuating oxygen levels during deposition, as evidenced by very high organic matter contents and mass mortality of juvenile bivalves. These anoxic periods have been interrupted by periods of bioturbation, with the development of extensive tiered ichnocoenoses. Phosphatization of Thalassinoides fills and subsequent modification of the phosphatic fill by compaction has brought about the formation of phosphate nodules. The typical Thalassinoides framework may be recognized on well-exposed bedding surfaces. The phosphate nodules also occur as conglomeratic lag deposits, commonly occurring at the base of siltstone beds, as a result of episodic heavy storms.

Tectonothermal analysis of high-temperature mylonitization in the Coimbra–Córdoba shear zone (SW Iberian Massif, Ouguela tectonic unit, Portugal): Evidence of intra-continental transcurrent transport during the amalgamation of Pangea

Mylonites in pelitic and quartzofeldsphatic gneisses from the Ouguela tectonic unit (Coimbra–Córdoba shear zone, SW Iberian Massif) have been studied as an example of high-temperature ductile deformation associated with transcurrent tectonics. Detailed microstructural and P– T analysis indicates that ductile deformation evolved from a metamorphic peak at approximately 650–750 °C and 7.5–9.5 kbar (quartzofeldsphatic gneisses) and 730–790 °C and 7.5–9.5 kbar (pelitic gneisses) to retrograde conditions at 500–575 °C and 4.5/5.5–6.5/7.5 kbar (quartzofeldsphatic gneisses) and 525–600 °C and 3.5/4.5–5.5/7.5 kbar (pelitic gneisses). Following the metamorphic peak, exhumation was very fast. The P– T trajectory, which does not reach the curve for granite melting, is distinct that of isothermal decompression. Instead, the progressive and contemporaneous decrease in pressure and temperature was a direct response to strong heat dissipation along the contacts between the ascending slice and the adjacent blocks. The horizontal component of exhumation path, calculated for middle and shallower crustal levels, sum to ca. 57 km to 94 km (for the pressure peak). Assuming this offset acted in the Viséan during a time interval of ca. 9 Ma, the estimated exhumation horizontal slip rate is in the order of 6.3 to 10.4 mm/yr, which corresponds to an exhumation oblique-slip exhumation rate of 6.6 to 10.7 mm/yr (for ductile deformation). These values indicate that the transcurrent tectonic displacements accommodated by these mylonitic are similar to those of modern intra-continental shear zones, such as the still active Karakoram Fault (8.3 mm/yr) in the Himalayas. The Coimbra–Córdoba shear zone is therefore a typical intra-continental transcurrent zone with ten-to-one hundred kilometre along-strike mass movement of material that aided the exhumation of deep crustal rocks. Study of this large-scale structure in the SW Iberian Massif is therefore central to models of orogenic deformation during the amalgamation of Pangea.

Tectonic control on the architecture of a Miocene carbonate ramp in the Central Apennines (Italy): Insights from facies and backstripping analyses

Analyses of facies associations and biotic assemblages integrated with backstripping analysis are presented to improve understanding of the development of a shallow water Miocene carbonate ramp in the Central Apennines (Italy), with special reference to the relationships between tectonic subsidence and the internal architecture of the ramp. Subsidence curves were calculated for six measured sections located in different sectors of the platform. Dating is derived from Sr isotope analyses (from previous studies) and regional correlations. Corrections for eustasy and paleobathymetry were deduced from biota and facies analyses. The subsidence curves show rates that vary both in space and time. By analysing the vertical motions in different sectors of the ramp over a fixed time span (Burdigalian to Tortonian), it was possible to evaluate the control on platform architecture exerted by tectonically induced changes in sea-floor bathymetry and highlight the effects of tectonic migration. Most analysed sites experienced a short period of tectonic uplift or stability followed by a period of slow subsidence. This preceded increased subsidence which resulted in drowning of the shallow-water carbonate platform. The stability/uplift is progressively younger towards the north-eastern sectors that correspond to progressively more external zones of the foreland relative to the Apenninic orogenic belt. The subsequent drowning is related to the diachronous down-flexure of the Adriatic lithosphere due to its eastward retreating subduction under the Apennines. The small magnitude of the uplift suggests that the formation of a foreland bulge due to subduction-related flexure of the Adriatic plate was probably not the responsible mechanism. Hence, this uplift is related to the development of proto-thrusts or to the propagation of compressive stresses in the foreland. These vertical motions influenced the geometry of the platform during the 17.5–16 Ma stage. During this period the platform was characterised by exceptional progradation of the bryomol-dominated proximal outer ramp facies belt. This rapid spreading may be induced by the combined effect of increased eutrophic conditions and a contemporaneous decrease in the sea-floor bathymetry resulting from the tectonic uplift. From the Tortonian onwards, when the platform became involved in the eastward migrating foredeep system, the tectonic subsidence curve records a short period of fast tectonic subsidence rates followed by a period of slow subsidence or slight uplift during basin drowning and infilling, respectively.

Survey of Quality of Life and Related Risk Factors for a Taiwanese Village Population 3 Years Post-Earthquake

To investigate quality of life (QOL) and related risk factors in Taiwanese earthquake survivors diagnosed with different psychiatric disorders 3 years after the 1999 Chi-Chi earthquake. This study was a population survey. Trained assistants used the Medical Outcomes Study Short Form-36 (MOS SF-36) and questionnaires to interview 405 respondents (189 men and 216 women) aged 16 years or older, who had been exposed to the earthquake. Psychiatrists interviewed the same respondents using the Mini-International Neuropsychiatric Interview, with an adjusted response rate of 70.2%. The prevalence range for psychiatric disorders in the earthquake survivors was 0.2-7.2% 3 years after the Chi-Chi earthquake, with rates for major depression (MD) and posttraumatic stress disorder (PTSD) of 6.4% and 4.4%, respectively. The QOL scores for the PTSD/MD group were lower than for the other two diagnostic groups, as determined by assessment of physical and mental aspects of functional integrity from MOS SF-36 scores. The predictors for poor QOL were age, female gender, economic problems, physical illness, subjective assessment of memory and social-activity decline and diagnosis of PTSD or MD. The QOL for earthquake survivors with psychiatric disorders, especially PTSD or MD, was inferior compared with the mentally healthy analogues, with contemporaneous decreases in mental and physical function scores across the QOL subscales. The persistence of long-term economic problems was one of many important factors affecting QOL.

Meiotic progression of isolated mouse spermatocytes under simulated microgravity.

Progression through the prophase of the first meiotic division can be obtained in culture by treatment of mouse spermatocytes with the serine/threonine phosphatase inhibitor okadaic acid. Chromosome condensation during this G2/M transition involves the activation of the MAPK pathway, which causes the activation of Nek2 and the phosphorylation of the chromatin architectural protein Hmga2. In an effort to set up conditions to allow a spontaneous progression of mouse spermatocytes through meiosis, we have investigated the cell-cycle features of these cells cultured for 24 h with a rotary cell culture system in a humidified atmosphere in a thermostatic incubator to simulate a microgravity environment. Morphological analysis of nuclear squashes indicated a 2-fold increase in late-pachytene spermatocytes with highly condensed chromosomes, and a contemporaneous decrease of mid-pachytene cells with less condensed chromatin. Microgravity induced a 2-fold activation of the cyclinB-cdc2 complex, confirming at the molecular level that cell-cycle progression had occurred. Moreover, using immuno-kinase assays with specific substrates we have demonstrated that the meiotic progression obtained under microgravity conditions is accompanied by activation of the Erk1/p90Rsk2 pathway. These data indicated that activation of the MAPK pathway correlates with chromatin condensation even under conditions in which meiotic progression occurs spontaneously and is not induced by a drug. We suggest that culture under microgravity conditions might help to release the block that inhibits isolated spermatocytes from progressing through prophase at unit gravity, and to study the physiological events of germ cell differentiation in vitro.

Reduction of Detyrosinated Microtubules and Golgi Fragmentation Are Linked to Tau-Induced Degeneration in Astrocytes

Several human neurodegenerative diseases are associated with abnormal accumulations of aggregated tau proteins and glial degeneration in astrocytes, but the mechanism whereby tau proteins cause astrocytic degeneration is unclear. Here, we analyzed the biological consequences of overexpressing the longest human tau isoform in primary cultures of rat astrocytes using adenoviral-mediated gene transfer. Significantly, we found specific decreases in stable detyrosinated [glutamate (Glu)] microtubules (MTs) with concomitant increases in tubulin biosynthesis and the accumulation of acetylated, tyrosinated, alpha- and beta-tubulin. The consequences of this selective reduction in stable Glu-MTs included contemporaneous decreases in kinesin levels, collapse of the intermediate filament network, progressive disruption of kinesin-dependent trafficking of organelles, fragmentation of the Golgi apparatus that culminated in atrophy, and non-apoptotic death of astrocytes. These results suggest that reduced stable Glu-MTs is a primary consequence of tau accumulation that initiates mechanisms underlying astrocyte dysfunction and death in human neurodegenerative glial tauopathies.

Geochemistry and Radioactive Potentiality of Um Naggat Apogranite, Central Eastern Desert, Egypt

Abstract: The northern part of Um Naggat granite massif (UNGM) has suffered extensive post‐magmatic metasomatic reworking which results into the development of (Zr, Hf, Nb, Ta, U, Th, F)– and albite‐enriched and greisenized apogranite body (UNAP) of 600 m thick, and more than 3 km in the strike length.Albitization produced an enrichment in Zr (av. 2384 ppm), Hf (61), Nb (419), and U (43). The Th/U ratio ranges between 1. 33 and 1. 90. Extreme albitization (i. e. the albitite rock) is characterized by sharp decrease in the rare metals contents. However, extreme greisenization (i. e. endogreisen bodies) is characterized by a considerable enrichment in Zr (av. 5464 ppm), Hf (143), Nb (2329), Ta (152), U (66) and Th (178). The Th/U ratio ranges between 1. 57 and 3. 60. In contrast to extreme greisenization, it seems that extreme albitization does not apparently change the fluid pH and therefore poor amounts of rare metals are localized in the albitites.It is suggested that the presence of Na+, H+ and F‐ in the ore fluids was essential to stablize complexes of Zr, Hf, Nb, Ta, U, Th, and HREE during extraction and transportation. In contrast, contemporaneous decrease of temperature and increasing pH due to decreasing pressure are considered the essential factors for localization of disseminated mineralization of Zr and Nb in the apical parts of the UNAP. The enhanced uranium content in the alteration facies of UNAP coupled with the absence of significant uranium mineralization may indicate the metalliferous rather than mineralized nature for the UNAP. The high uranium contents are stabilized in refractory accessory minerals. However, with repect to Zr and Nb, the UNAP especially the albitized and greisen facies, can be categorized as a mineralized productive granite.

Differentiation of Y79 cells induced by prolonged exposure to insulin.

Y79 human retinoblastoma cells are known to contain receptors for both insulin and insulin-like growth factors (IGFs), to produce these cytokines and release them in the culture medium. Previously we have demonstrated that IGFs and insulin stimulate Y79 cell proliferation through the involvement of type I IGF receptor and Insulin Receptor Substrate 1 (IRS-1). This paper studies the effect of prolonged exposure to insulin on Y79 cells. Cells grown for 10 days in the presence of insulin were reseeded and incubated once more with insulin. In the reseeded cells proliferation lowered and morphological changes appeared. After 10 days of reseeding, cells stopped proliferating and showed long ramifying neurite processes and varicosities consistent with neuronal differentiation. Morphological differentiation was accompanied by a marked increase in the content of total protein and in that of tubulin, the major protein constituent of microtubules, a marked increase in the content of specialized protein markers of dopaminergic and cholinergic differentiation (dopamine beta-hydroxylase and choline acetyltransferase activities, respectively); a contemporaneous decrease in the content of glial fibrillary acidic protein (GFAP), a specific marker of glial cells, was also observed. Our results demonstrate that prolonged exposure to insulin induces Y79 cells to differentiate into a neuronal-like phenotype. At this moment it is not possible to establish the mechanism by which insulin induces this differentiative effect.

On the albite-enriched granitoids at Um Ara area, Southeastern Desert, Egypt. 1. Geochemical, ore potentiality and fluid inclusion studies

A radioactive and metasomatically albite-enriched microgranite (apogranite, 556 Ma) stock was emplaced at the northern contact of Um Ara monzogranite pluton (589 Ma). Rock/fluid interaction within the apogranite is well displayed as petrographical and geochemical zonal patterns in response to K- and Na-metasomatism. The metasomatic reactions commenced with addition of K +, Rb + and Pb 2+ (amazonitization) followed by Na + (albitization) and finally with Mn- and Fe-oxide alteration. A gradual and gross enrichment of Nb, Y, Zr, Li, Zn, U, Th and F occurs from the amazonitized to albitized zone. p]Microthermometric study of fluid inclusions in quartz of the amazonitized and albitized microgranites indicates that high to moderate temperature, saline fluids interacted with the solidified microgranite cupola in the early metasomatic processes. Inclusions of the K-enriched zone homogenize in the range of 285–425 °C, with salinities of 7–22.1 wt.% NaCl equivalent. However, inclusions in the later fracture and joint-filling quartz veins and fluorite veinlets homogenize in the range of 190–310 °C, with salinities of 2–5.1 wt.% NaCl equivalent. It is suggested that the presence of K +, Na + and F − in the ore fluids was essential to stablize complexes of the rare metal elements during extraction and transportation. In contrast, contemporaneous decrease of temperature and salinity, loss of CO 2 and increasing pH due to decreasing pressure are considered the essential factors for localization of disseminated mineralization of Zr, Y, Nb, Zn and Th and the fracture-filling with U in the apical parts of the Um Ara apogranite stock.

Calibration of Radiocarbon Ages and the Interpretation of Paleoenvironmental Records

Calibration of the radiocarbon timescale of paleoecological records is essential if they are to be explained correctly in terms of their governing ecological or climatological controls. The differences between calendar ages and radiocarbon ages that arise from variations in 14C production through time can distort the chronologies of individual records and the interpretations based on them. Misleading impressions of synchrony or diachrony of events among multiple records can result, and estimates of the apparent duration of episodes and rates of sedimentation and local population changes can be biased. Displays of the temporal patterns of migration or extinction may also be affected. Spurious correlations may arise between records with radiocarbon-controlled chronologies and time series of potential controls that are expressed on a calendar time scale. Support for particular explanations of features in a paleoecological record may vary depending on whether radiocarbon ages are calibrated or not. This situation is illustrated using the eastern Beringian Populus subzone as an example. When the radiocarbon ages that control the timing of the Populus subzone are calibrated, the contemporaneous decrease in ice volume and increase in summer insolation are implicated as the ultimate controls of the occurrence of the subzone.

Electrical conductivity of lithium-intercalated thiophosphate NiPS3 single crystals.

Conductivity measurements were made on lithium-intercalation complexes ${\mathrm{Li}}_{\mathit{x}}$${\mathrm{NiPS}}_{3}$ both during the intercalation process and after the intercalation has ceased. The intercalation process was characterized by means of the conductivity measurements as a function of the intercalation time. Results for equilibrated samples are presented as a function of both the temperature and the lithium concentration. An overall and quick increase in the electrical conductivity, a contemporaneous decrease in the activation energy, and a degenerate semiconducting behavior at high lithium contents were observed. All these effects suggest that, with respect to the pure ${\mathrm{NiPS}}_{3}$, a new conduction mechanism occurs at a different energy level from the very beginning of the intercalation process. Taking the probable nickel reduction into account, a possible identification of the lithium 2s electron-accepting levels is proposed. In the early intercalation times a simple empirical model is formulated to correlate the data as a function of the intercalation time and as a function of temperature.

Thermodynamics of oxygen binding to arctic hemoglobins The case of reindeer

The most surprising characteristic of reindeer hemoglobin (Hb) concerns its response to changes in temperature. Thus, the shape of the oxygen-binding curve is strongly temperature dependent due to the difference in the enthalpy of oxygenation between the T and R state of the molecule. In fact, delta H of oxygen binding to the T state is strongly exothermic whereas that of the R state is very close to zero or possibly positive after correction for the heat of oxygen solubilization. Moreover, the allosteric transition T0----R0 has been found to display a negative delta H and a contemporaneous decrease in entropy, a behavior which is precisely the opposite of what has been reported for other hemoglobins. As a whole, reindeer Hb represents a beautiful example of the significance that comparative studies may have in assessing the general validity of the main properties of the hemoglobin molecule.

The incidence of Down's syndrome over a 19-year period with special reference to maternal age.

The incidence of Down's syndrome in the Liverpool and Bootle areas from 1961 to 1979 was investigated. A total of 319 liveborn cases was ascertained over this period. Using 3-year moving averages, the incidence of the condition fell gradually from 1.62 per 1000 livebirths for 1961 to 1963 to 1.09 per 1000 livebirths for 1977 to 1979. This trend is significant at the 0.1% level. Over the same period the mean maternal age of Down's syndrome births fell gradually from 36.7 years in 1961 to 29.0 years in 1979. This trend is significant at the 1% level. There was a contemporaneous decrease in the proportion of total births to women over 35 years in the study area. Cytogenetic analysis was performed on 175 out of the 319 index cases (54.9%). Of these, there were 161 trisomies (92%), 11 translocations (6.3%), and three mosaics (1.7%). Between 1969 and 1979 four terminations of pregnancy for Down's syndrome were performed, all for trisomy. Quinquennial age specific incidences for Down's syndrome were calculated for the years 1960 to 1964, 1965 to 1969, 1970 to 1974, and 1975 to 1979. There have been no statistically significant changes over this time. It is suggested that the fall in incidence of Down's syndrome can be explained by the fall in mean maternal age.

X-ray observations of the Seyfert 1 galaxies AKN 120 and MCG 8-11-11

A new X-ray source, H0523-00, with the optically variable Seyfert 1 galaxy AKN 120 is identified. The source has a 2-10 keV X-ray flux of 2 x 10 to the -11th ergs/sq cm s which corresponds to a 2-10 keV X-ray luminosity of 10 to the 44th ergs/s. X-ray observations over a 1.5 year time span combined with contemporaneous optical photometry show a decrease in the optical with no corresponding decrease in the X-ray. In contrast, similar observations of MCG 8-11-11 show a contemporaneous decrease in optical and X-ray fluxes. It is noted that the infrared and X-ray spectral slopes for these two objects are similar, with the optical being steeper by roughly one unit.

The palaeogeography of mid- and east Europe during the last cold stage, with west European comparisons

In this review of work on mid- and east European palaeogeography during the last cold stage the author has used a stratigraphic division based on deep-sea sediments in the Atlantic. Difficulties apparent in palaeogeographical reconstructions are discussed. In such reconstructions the sequences of permafrost structures, loesses, fossil soils, slope sheets, fluviatile sediments, vegetation, glacial deposits and land forms are analysed. The consideration of events in both their stratigraphic order (time scale) and their areal distribution in Europe has enabled the author to give a far more accurate indication of temperature and moisture changes in the different parts of Europe. Contrasts revealed by a section through east and west Europe reflect differences in the evolution of permafrost, in the succession of vegetation and soils, and in the history of glaciation. Their source was the different degree of climatic continentality which increased throughout the last cold stage. Continentality was characterized by the contemporaneous decrease in temperature, increase in temperature amplitudes and decrease in precipitation values. The presence of permafrost in Europe was responsible for the different development of biota. This makes for difficulty in reconstructing palaeogeographic conditions on the basis of actualism.

Paradoxic changes in chronic intravascular coagulation

Paradoxic changes in platelet and fibrinogen levels were found in chronic intravascular coagulation induced in dogs. After pre-experiment base-line values were obtained with saline alone, thrombaplastin (acetone-dried dog-brain emulsion in saline, clarified by centrifugation) was given by continuous intravenous infusion at 2.5 ml/hr for 5 to 7 days. With undiluted thromboplastin, fibrinogen and platelet levels steadily fell and then stabilized at 50–100 mg/100 ml of plasma for fibrinogen and 5-10 × 103/mm3 for platelets. Fibrinogen decreased more rapidly than platelets. Infusion of a 10-fold dilution of thromboplastin paradoxically increased fibrinogen to 550–650 mg/100 ml but with contemporaneous decrease of platelets to 20–40 × 103/mm5. With 100-fold dilution of thromboplatin the fibrinogen also increased, to more than 500 mg/100 ml, while the platelets remianed in the normal range. Whenever the thromboplastin infusion was stopped, platelets and fibrinogen levels increased, exceeding the preinfusion level and remaining high for 2 to 3 weeks. These data suggest that, in chronic intravascular coagulation in the dog, the liver is better able to compensate in the synthesis of fibrinogen than the marrow can in the synthesis of platelets. When intravascular coagulation is not too profound, fibrinogen or platelets may be normal or increased, as we have found in some patients who had evidence of intravascular coagulation without hypofibrinogenemia and thrombocytopenia.