The paper outlines the history of space missions for discovery and observation of near-earth objects, whose orbits are within that of the Earth, with using Venus gravity to enter the orbits ...advantageous for observing the Atira asteroids.
The Cadia porphyry gold-copper district is the largest hydrothermal, intrusion-related gold deposit in eastern Australia. Discovered in 1992 by Newcrest Mining Limited, pre-mine resources in the ...district were in excess of 585 t Au and 2.35 Mt Cu. The Cadia district lies within shoshonitic subaqueous volcanic rocks of the Late Ordovician Molong Volcanic Belt in the eastern Lachlan Fold Belt (LFB) of New South Wales. An island arc tectonic setting is envisaged for the formation of these volcanic rocks, but the nature of the arc basement and geometry of the subduction zone(s) is debated. Mineralisation occurs in four principal porphyry deposits (Cadia Hill, Cadia Ridgeway, Cadia East/Cadia Far East and Cadia Quarry) as sheeted and stockwork quartz-sulfide veins, and locally as broadly stratabound disseminated mineralisation (Cadia East) and skarn (Big Cadia and Little Cadia). All of the porphyry deposits show a close spatial association with shoshonitic monzodiorite to quartz monzonite dykes and stocks of the Cadia Intrusive Complex (CIC). Gold-copper mineralisation is hosted by these intrusions and also by the enclosing Forest Reefs Volcanics (FRV) wall rocks. Hydrothermal alteration associated with mineralisation is potassic, which is overprinted by selectively pervasive propylitic and silica-albite assemblages. Petrological studies and major and trace element analysis of rocks of the CIC and FRV, as well as of other intrusions in the Cadia district that appear unrelated to mineralisation, have been conducted. Unaltered samples from the CIC are characterised by high K^sub 2^O contents (up to 6.5 wt%) and molecular K/Na ratios consistently >1, confirming the alkalic and shoshonitic nature of the complex. The CIC samples also fall just within the shoshonite field on Ce/Yb-Ta/Yb and Th/Yb-Ta/Yb plots, although immediately adjacent to the calc-alkaline field. The FRV are geochemically similar to the CIC, although lower in P^sub 2^O^sub 5^ and Ce (LREE). Dacitic and hornblende porphyry intrusions from within the district, but spatially unrelated to mineralisation, have a distinctive geochemical signature and are not shoshonitic in composition. The close spatial association between gold-copper mineralisation and the shoshonitic, monzonitic CIC argues strongly for a genetic link between the two. A similar association occurs at the economic Goonumbla porphyry gold-copper deposits in the eastern LFB, while sub-economic gold-copper mineralisation at Cargo and Copper Hill is associated with calc-alkaline quartz diorite and dacitic intrusions. The Cadia district is considered to be an excellent example of the association of alkaline, potassic magmas and gold-copper porphyry style mineralisation.PUBLICATION ABSTRACT
Circularly polarized soft x-rays have been used with an imaging photoelectron microscope to record images of magnetic domains at a spatial resolution of 1 micrometer. The magnetic contrast, which can ...be remarkably large, arises from the fact that the x-ray absorption cross section at inner-shell absorption edges of aligned magnetic atoms depends on the relative orientation of the photon spin and the local magnetization direction. The technique is element-specific, and, because of the long mean free paths of the x-rays and secondary electrons, it can record images of buried magnetic layers.
The Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 3830 kilometers of asteroid 433 Eros on 23 December 1998. The gravitational perturbation on NEAR was evident in the spacecraft ...tracking data. Ground-based Doppler and range tracking of the spacecraft as well as spacecraft images of the asteroid's center of figure and surface features were used to determine the mass and rotation pole of Eros. The mass of Eros is (7.2 ± 1.8) × 10$^{18}$ grams and, coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a bulk density of 2.5 ± 0.8 grams per cubic centimeter. The rotation pole position is 15.6 (±3.7) degrees in right ascension and 16.4 (±1.8) degrees in declination, which is consistent with ground-based and NEAR imaging team observations.
Abstract
The big-clawed snapping shrimp, Alpheus heterochelis, is found in size-matched male-female pairs. A common assumption is that a large size advantage in males, an extended pair bond, and a ...positive correlation between female size and fecundity promotes size-assortative pairing. Since all of these conditions apply to A. heterochelis, we investigated size-assortative pairing in the laboratory by designing experiments in which the pairs were size matched or mismatched using three size categories; large, medium and small. We found that snapping shrimps prefer to pair according to size and that such pairing is stable. We also found that, contrary to the initial assumptions, female-female competition and female choice for large males plays the main role in the pair formation process. Smaller, and hence less competitively successful, females will pair with smaller males, but in a male-biased environment, will preferentially pair with larger males. Large males provide the best protection from shelter eviction, which is crucial for female A. heterochelis, as their reproduction is closely associated with moult, and therefore requires shelter and a male present for successful reproduction.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Introduction
Introduction of a surgical insult in conjunction with orthodontic therapy has been shown to accelerate treatment in minor tooth movement and comprehensive orthodontic cases by induction ...of the regional acceleratory phenomenon (RAP). When applying this concept to a molar tipped into an adjacent edentulous site, a dental implant can be planned to anchor the movement.
Case Presentation
A generally and periodontally healthy 25‐year‐old patient presented missing tooth #19, with tooth #18 mesially tipped into the first molar crown space. A dental implant was placed in the #19 position. Following osseointegration, the implant anchored orthodontic movement of the adjacent tooth, which was initiated in conjunction with third molar extraction.
Conclusion
Favorable biomechanics for molar uprighting can be achieved using an osseointegrated implant and a customized orthodontic device. The presented technique facilitates implant site development without delaying placement of the fixture and simplifies fabrication of a harmonious and anatomic implant‐supported restoration. Induction of the RAP may hasten treatment completion.
Food response preceding and following exposure to Cu concentrations of 0.00, 0.02, and 0.2 mg/L was observed in male and female Cambarus bartonii from an uncontaminated, freshwater lake. The animals ...were tested in a Y-maze. Control animals demonstrated food localization, and the treated animals, either no localization or slight food avoidance. The latency for localization in the Cu-exposed males increased. Females revealed slight increases in latency. There were no significant differences between the low and the high Cu concentration groups in food detection or latency. However, there was an increase in mortality in the higher concentration group and significant difference in mortality among three copper concentrations (P<0.02). Females seem to recover from Cu-induced impairment slightly faster than males, suggesting a more efficient mechanism for detoxifying copper. Female mortality, however, remained equally high in the high Cu concentration group. The toxic effects of copper persist after removal of the toxicant and occur at concentrations much lower than reported lethal levels.
Carbon monoxide (CO) poisoning is associated with variable neuropsychological deficits, depending on levels of CO exposure and individual differences. Studies to date have reported variable findings, ...as their subjects have been exposed to different levels of CO from different poisoning sources. Four unique case studies are presented, all of whom experienced the same level of CO poisoning (17-29%) in the same accident. Two of the individuals were brothers with an identical genetic disorder (i.e. syndactylism) and the other two were brother/sister. The results indicated: (1) variable neuropsychological deficits despite similar levels of CO poisoning; (2) consistent estimated decline in intelligence; (3) similar memory decline for the two brothers, but not for the brother and sister; and (4) consistent late-onset emotional-behavioural difficulties. The results also suggested that the neuropsychological and emotional-behavioural deficits had an impact on the individual's ability to work.
Sporadic Parkinson's disease (sPD) is a nervous system-wide disease that presents with a bradykinetic movement disorder and frequently progresses to include depression and cognitive impairment. ...Cybrid models of sPD are based on expression of sPD platelet mitochondrial DNA (mtDNA) in neural cells and demonstrate some similarities to sPD brains. In sPD and CTL cybrids we characterized aspects of mitochondrial biogenesis, mtDNA genomics, composition of the respirasome and the relationships among isolated mitochondrial and intact cell respiration. Cybrid mtDNA levels varied and correlated with expression of PGC-1α, a transcriptional co-activator regulator of mitochondrial biogenesis. Levels of mtDNA heteroplasmic mutations were asymmetrically distributed across the mitochondrial genome; numbers of heteroplasmies were more evenly distributed. Neither levels nor numbers of heteroplasmies distinguished sPD from CTL. sPD cybrid mitochondrial ETC subunit protein levels were not altered. Isolated mitochondrial complex I respiration rates showed limited correlation with whole cell complex I respiration rates in both sPD and CTL cybrids. Intact cell respiration during the normoxic–anoxic transition yielded
K
m values for oxygen that directly related to respiration rates in CTL but not in sPD cell lines. Both sPD and CTL cybrid cells are substantially heterogeneous in mitochondrial genomic and physiologic properties. Our results suggest that mtDNA depletion may occur in sPD neurons and could reflect impairment of mitochondrial biogenesis. Cybrids remain a valuable model for some aspects of sPD but their heterogeneity mitigates against a simple designation of sPD phenotype in this cell model.
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