Evidence for Multiple Diagenetic Episodes in Ancient Fluvial-Lacustrine Sedimentary Rocks in Gale Crater, Mars

The Curiosity rover's exploration of rocks and soils in Gale crater has provided diverse geochemical and mineralogical data sets, underscoring the complex geological history of the region. We report the crystalline, clay mineral, and amorphous phase distributions of four Gale crater rocks from an 80-m stratigraphic interval. The mineralogy of the four samples is strongly influenced by aqueous alteration processes, including variations in water chemistries, redox, pH, and temperature. Localized hydrothermal events are evidenced by gray hematite and maturation of amorphous SiO2 to opal-CT. Low-temperature diagenetic events are associated with fluctuating lake levels, evaporative events, and groundwater infiltration. Among all mudstones analyzed in Gale crater, the diversity in diagenetic processes is primarily captured by the mineralogy and X-ray amorphous chemistry of the drilled rocks. Variations indicate a transition from magnetite to hematite and an increase in matrix-associated sulfates suggesting intensifying influence from oxic, diagenetic fluids upsection. Furthermore, diagenetic fluid pathways are shown to be strongly affected by unconformities and sedimentary transitions, as evidenced by the intensity of alteration inferred from the mineralogy of sediments sampled adjacent to stratigraphic contacts.

Modeling of x-ray fluorescence full field imaging using planar square pore micro-channel plate optics

X-ray fluorescence imaging using perfect planar square pore micro-channel plate x-ray optics (MPO) is investigated through the modeling of the MPO point spread function (PSF). A semi-continuous model based on the use of a simplified two parameters reflectivity curve is developed including, in particular, three kinds of contributions. A validation of this model is carried out by calculating variations of several PSF characteristics with the MPO and fluorescence imaging parameters and comparing the results with ray-tracing simulations. A good agreement is found in a large range of x-ray energies; however, it is shown that for the lower values of the working distance a discrete model should be used to take into account the periodic nature of the PSF. Ray-tracing simulated images of extended monochromatic sources are interpreted in light of both the semi-continuous and discrete models. Finally, solutions are proposed to improve the imaging properties of the MPOs.

Comparison of coaches' perceptions and officials guidance towards health promotion in French sport clubs: a mixed method study

Despite the call to improve health promotion (HP) in sport clubs in the existing literature, little is known about sport clubs' organizational capacity. Grounded within the setting-based framework, this study compares HP activities and guidance among 10 football clubs. At least three grassroots coaches from each club (n = 68) completed the Health Promoting Sports Clubs scale to assess their perceptions of HP; an official (n = 10) was interviewed about club's activities and official's guidance provided to coaches. A concurrent embedded design with quantitative results guiding the qualitative analysis was used. Despite no significant differences regarding coaches' perceptions of HP between the 10 sport clubs, except for the policy dimension, officials' interviews revealed some contradictions. Sport participation was recognized as automatically promoting HP, meaning that sport practice entails many benefits, without questioning the nature of the activities. HP was considered as a secondary aim in regard to sport performance, leading to the lack of written policies, partnerships and sporadic HP activities. Future interventions should consider: (i) the creation of required policy and long-term vision; (ii) the link between HP and sport performance; (iii) the rootedness of sport clubs within their community and (iv) guidelines towards HP from sport federations.

Evaluation of the Coaches Educators training implementation of the PAPA project: A comparison between Norway and France

This study cross-culturally compares the implementation process of the Empowering Coaching™ training program to grassroots coaches (GCs) by trained Coach Educators (CEs) from the Promoting Adolescent Physical Activity project in Norway and France. This program targets children's health through coach training to create a more positive environment. Using the RE-AIM framework, indicators of implementation processes at staff level were defined for adoption, implementation, and maintenance. CEs (n = 18) were interviewed about their professional use of the training, and video-filmed delivering the intervention trial workshops. GCs (n = 185) responded to a questionnaire after the workshops. Results showed that CEs were keen to participate in this project (16/18; 89%), to stay involved (12/16; 75%), and to diffuse the principles after the research project (12/12; 100%). CE training seemed effective as results indicated that CEs applied the principles of the program during the workshops and covered a high degree of the content (78%). Cross-cultural differences were found as the French Football Federation CE dropped out of the program, as Norwegian CEs delivered the content with higher fidelity and had higher enjoyment and pace scores than French CEs. More indicators are needed to use the RE-AIM framework for cross-cultural comparison.

Mineralogy of a mudstone at Yellowknife Bay, Gale crater, Mars

Sedimentary rocks at Yellowknife Bay (Gale crater) on Mars include mudstone sampled by the Curiosity rover. The samples, John Klein and Cumberland, contain detrital basaltic minerals, calcium sulfates, iron oxide or hydroxides, iron sulfides, amorphous material, and trioctahedral smectites. The John Klein smectite has basal spacing of ~10 angstroms, indicating little interlayer hydration. The Cumberland smectite has basal spacing at both ~13.2 and ~10 angstroms. The larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating H2O retention. Basaltic minerals in the mudstone are similar to those in nearby eolian deposits. However, the mudstone has far less Fe-forsterite, possibly lost with formation of smectite plus magnetite. Late Noachian/Early Hesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time.

X-ray diffraction results from Mars Science Laboratory: mineralogy of Rocknest at Gale crater

The Mars Science Laboratory rover Curiosity scooped samples of soil from the Rocknest aeolian bedform in Gale crater. Analysis of the soil with the Chemistry and Mineralogy (CheMin) x-ray diffraction (XRD) instrument revealed plagioclase (~An57), forsteritic olivine (~Fo62), augite, and pigeonite, with minor K-feldspar, magnetite, quartz, anhydrite, hematite, and ilmenite. The minor phases are present at, or near, detection limits. The soil also contains 27 ± 14 weight percent x-ray amorphous material, likely containing multiple Fe(3+)- and volatile-bearing phases, including possibly a substance resembling hisingerite. The crystalline component is similar to the normative mineralogy of certain basaltic rocks from Gusev crater on Mars and of martian basaltic meteorites. The amorphous component is similar to that found on Earth in places such as soils on the Mauna Kea volcano, Hawaii.

Curiosity at Gale crater, Mars: characterization and analysis of the Rocknest sand shadow

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.

How to increase academic performance in children with oppositional defiant disorder? An implicit theory effect

The aim of the present study was to determine whether the implicit theory effect extends to children with oppositional defiant disorder (ODD), with academic difficulties. Twenty-five male children, aged 8-11 years with ODD were randomly assigned to one of two experimental conditions (Incremental Theory highlighting the possibility of self-improvement vs. control). An increase of cognitive performance (IQ) was found for children with ODD in the incremental condition, but not in the control condition. This cognitive improvement could be viewed as a protective factor for children and adolescents with ODD on academic setting.

Surfactant (TTAB) role in the preparation of 2,7-Poly(9,9-dialkylfluorene-co-fluorenone) nanoparticles by miniemulsion

The role of tetradecyltrimethylammonium bromide (TTAB) and its partition between water, chloroform, and the chloroform/water interface during the miniemulsification of a photoluminescent polymer was investigated by indirect interfacial tension/elasticity measurements. Dynamic interfacial tension and elasticity measurements showed the presence of a gas-liquid phase transition at the chloroform/water interface and the formation of a rigid interface, which was supposed to promote emulsion stability. The parameters of the adsorption isotherms and the TTAB partition coefficient were obtained from surface tension isotherms. Dynamic surface tension measurements performed after TTAB water/chloroform extraction were used to compute TTAB partition between water, chloroform, and the chloroform/water interface. Model calculations allowed identifying (for the tested conditions) the minimum size of emulsion droplets before the onset of instability and the segregation of a sizable amount of TTAB in the final polymer nanoparticles, which induced a shift in the 2,7-poly(9,9-dialkylfluorene-co-fluorenone) (PF) photoluminescence emission band. The size of the emulsion droplets of the final polymer particles and the amount of segregated TTAB were in good agreement with the corresponding experimental values.

Short- and long-term olivine weathering in Svalbard: implications for Mars

Liquid water is essential to life as we know it on Earth; therefore, the search for water on Mars is a critical component of the search for life. Olivine, a mineral identified as present on Mars, has been proposed as an indicator of the duration and characteristics of water because it dissolves quickly, particularly under low-pH conditions. The duration of olivine persistence relative to glass under conditions of aqueous alteration reflects the pH and temperature of the reacting fluids. In this paper, we investigate the utility of 3 methodologies to detect silicate weathering in a Mars analog environment (Sverrefjell volcano, Svalbard). CheMin, a miniature X-ray diffraction instrument developed for flight on NASA's upcoming Mars Science Laboratory, was deployed on Svalbard and was successful in detecting olivine and weathering products. The persistence of olivine and glass in Svalbard rocks was also investigated via laboratory observations of weathered hand samples as well as an in situ burial experiment. Observations of hand samples are consistent with the inference that olivine persists longer than glass at near-zero temperatures in the presence of solutions at pH approximately 7-9 on Svalbard, whereas in hydrothermally altered zones, glass has persisted longer than olivine in the presence of fluids at similar pH at approximately 50 degrees C. Analysis of the surfaces of olivine and glass samples, which were buried on Sverrefjell for 1 year and then retrieved, documented only minor incipient weathering, though these results suggest the importance of biological impacts. The 3 types of observations (CheMin, laboratory observations of hand samples, burial experiments) of weathering of olivine and glass at Svalbard show promise for interpretation of weathering on Mars. Furthermore, the weathering relationships observed on Svalbard are consistent with laboratory-measured dissolution rates, which suggests that relative mineral dissolution rates in the laboratory, in concert with field observations, can be used to yield valuable information regarding the pH and temperature of reacting martian fluids.

The trichotomous model and investment in learning to prepare for a sport test: a mediational analysis

BACKGROUND

Contemporary views on motivation suggest that the approach-avoidance achievement goals conceptualization--namely the trichotomous model--can shed light on the important issue of student motivation.

AIMS

To test the predictive value of the trichotomous model on the investment in learning a sport task for test preparation, and to validate a model which included a set of psychological processes (i.e., state anxiety and competence valuation) which mediate the relationship between the three goals (i.e., performance-approach, performance-avoidance, and mastery goals) and test preparation. The study was designed to investigate the direct and mediational effects of three experimental goal conditions on the time in which pupils prepared for a sport test.

SAMPLE

French male school pupils (N = 75). Pupils were aged 13-15 years and attended schools in southern France.

METHOD

Pupils prepared themselves for a sport task with a 5-minute period of training, and performed in one of three experimental conditions to which they were randomly assigned: a performance goal with a positive outcome focus (performance-approach), a performance goal with a negative outcome focus (performance-avoidance), or a mastery goal.

RESULTS

Pupils in the performance-avoidance group reported higher state anxiety and lower competence valuation than those in the performance-approach and mastery groups, and this psychological state was associated with less time taken to prepare for the test.

CONCLUSION

School pupils placed in an examination preparation context that elicits a performance goal with a negative outcome focus (performance-avoidance) show motivational deficits which manifest themselves in less time spent practising. The trichotomous model appears to be valid for the study of motivational processes in school physical education.

Perceptions of competence, implicit theory of ability, perception of motivational climate, and achievement goals: a test of the trichotomous conceptualization of endorsement of achievement motivation in the physical education setting

To test and extend the conceptualization of the endorsement of achievement goals in the physical education setting Mastery, Performance-approach, and Performance-approach goals, Perception of the physical education competence, Implicit theory about sport ability, and Perception of the motivational climate were assessed among 682 boys attending five French schools. Analysis indicated that (1) Performance-approach goals were positively associated with perception of physical education Competence, Entity beliefs about sport ability, the Performance dimension of the motivational climate, and negatively associated with Incremental beliefs about sport ability. (2) Mastery goals were positively associated with perception of physical education Competence, Incremental beliefs about sport ability, the Mastery dimension of the motivational climate, and negatively associated with the Performance dimension of the motivational climate. Also, (3) Performance-avoidance goals were positively associated with Entity beliefs about sport ability and the Performance dimension of the motivational climate; these goals were negatively associated with Incremental beliefs about sport ability and perception of physical education Competence. These results clearly attested to the validity of the trichotomous model in the physical education setting.

Characterization of the prostaglandin receptors in human osteoblasts in culture

Prostaglandins have complex actions on bone metabolism that depend on interactions with different types and subtypes of receptors. Our objective was to characterize the prostaglandins receptors present in primary cultures of human osteoblasts. RT-PCR analysis revealed the presence of DP, EP(4), IP, FP and TP receptor mRNA in primary cultures of human osteoblasts. FP receptor mRNA was detected only after 3 weeks of confluency, all the others were detected at every culture time tested. To verify the functionality of these receptors we challenged the cells with the prostanoids and synthetic analogues and determined the intracellular levels of cAMP. All receptors found by RT-PCR were coupled to second messengers except for the DP subtype. These results clearly show the presence of functional EP(4), IP, FP and TP receptors in human osteoblasts in culture.

Landed XRD/XRF analysis of prime targets in the search for past or present Martian life

Mars landers seeking evidence for past or present life will be guided by information from orbital mapping and from previous surface exploration. Several target options have been proposed, including sites that may harbor extant life and sites most likely to preserve evidence of past life These sites have specific mineralogic characteristics. Extant life might be gathered around the sinters and associated mineral deposits of rare active fumaroles, or held within brine pockets and inclusions in a few evaporite-mineral deposits. Possibilities for fossilization include deltaic and lake-bottom sediments of once-flooded craters, sinters formed by ancient hot-spring deposits, and the carbonate deposits associated with some evaporite systems. However, the highly varied mineralogy of fossil occurrences on Earth leads to the inference that Mars, an equally complex planet, could host a broad variety of potential fossilizing deposits. The abundance of volcanic systems on Mars and evidence for close associations between volcanism and water release suggest possibilities of organism entrapment and mineralization in volcaniclastic deposits, as found in some instances on Earth. Thus the targets being considered for exploration include a wide variety of unique deposits that would be characterized by silica or various nonsilicate minerals. Beyond these "special" deposits and in the most general case, an ability to distinguish mineralized from uncemented volcanic detritus may be the key to success in finding possible fossil-bearing authigenic mineralogies. A prototype miniaturized X ray diffraction/X ray fluorescence (XRD/XRF) instrument has been evaluated with silica, carbonate, and sulfate minerals and with a basalt, to examine the capabilities of this tool in mineralogic and petrologic exploration for exobiological goals. This instrument. CHEMIN (chemical and mineralogical analyzer), is based on an innovative low-power X ray tube, transmission geometry, and CCD collection and discrimination of diffracted and fluoresced X rays. The ability to accumulate and integrate the entire circumference of each complete Debye diffraction ring compensates for poor powder preparations, as might be produced by robotic sampling systems. With CHEMIN, a wide range of minerals can be uniquely identified. Using Rietveld analysis of the XRD results, mineral quantification is also possible. Expanded capabilities in phase analysis and constrained data solutions using quantitative XRD and XRF are within reach.

Induction of cyclooxygenase-2 by parathyroid hormone in human osteoblasts in culture

OBJECTIVE

Parathyroid hormone (PTH) induced bone resorption by osteoclasts depends on the presence of osteoblasts. PTH induced production of prostaglandins by osteoblasts and induction of bone resorption by prostaglandins suggest that these autacoids may be implicated in the effects of PTH on bone. Our objective was to determine if the increase in prostaglandin production induced in human osteoblasts by PTH is due to an increase in cyclooxygenase-2 (COX-2) expression.

METHODS

Primary cultures of human osteoblasts were obtained from specimens of trabecular bone. Confluent cells were treated with PTH, dexamethasone or compound NS-398, a specific COX-2 inhibitor. The concentration of prostaglandin E2 (PGE2) in the supernatants was determined by radioimmunoassay and COX-2 mRNA levels evaluated by Northern blot.

RESULTS

PTH induced COX-2 mRNA expression and PGE2 production. These effects were time and concentration dependent and were inhibited by dexamethasone. Compound NS-398 reduced PGE2 production to the same extent as dexamethasone, and neither compound had an additive effect on this variable.

CONCLUSION

These results show that PTH induces COX-2 expression in human osteoblasts in culture and suggest that this isoenzyme is the main factor in the control of prostaglandin synthesis in these experimental conditions.

Achievement goals and perceived ability predict investment in learning a sport task

BACKGROUND

Contemporary views on motivation suggest that expectancy-value and social-cognitive perspectives can shed light on the important issue of student motivation.

AIMS

To test the predictive value of achievement goals on the investment in learning a sport task. Two studies investigated whether investment in learning is affected by achievement goals and perceived ability.

SAMPLES

Study 1: 57 school pupils selected from an initial sample of 212. Study 2: 99 pupils selected from 400. Selection was based on motivation and perceived ability scores from questionnaires. Pupils were aged 13-15 years and attended schools in northern France.

METHODS

In Study 1 pupils prepared themselves for a sport task with a five-minute period of training. Study 2 pupils prepared themselves with a five-minute period of training after prior failure.

RESULTS

Study 1 showed that those who were ego-involved with a low perceived ability had a weaker investment in the training situation than those ego-involved with a high perceived ability, or those task-involved regardless of their perceived ability. Ego-involved pupils used an attributional bias to minimise the effect of effort on performance. Study 2 confirmed these results by underlining the motivational deficits of ego involvement for those with a low perceived ability.

CONCLUSIONS

School pupils with high ego involvement in a sport task and low perceived ability show motivational deficits which manifest themselves in less time spent on practising a task. A social-cognitive and expectancy-value perspective appears to be valid for the study of motivational processes in school physical education.

Development of scales to measure perceived physical education class climate: a cross-national project

Motivational research in the classroom has adopted a social cognitive perspective but has mainly been restricted to the study of individual achievement cognitions. In addition to this, there is a need to study and assess the perception children have of the class climate. Using social cognitive theory as a base, this research reports the development of class climate scales in French and English for use in physical education classes. Psychometric development with the French scale was shown to be satisfactory, including adequate factorial structure assessed by exploratory and confirmatory factor analysis (CFA), and good internal and test-retest reliability. A parallel English scale demonstrated a less adequate fit to the proposed model when using CFA, but shortened scales assessing just mastery and performance dimensions of climate were shown to predict important motivational measures in a structural equation modelling analysis.