Centimeter to decimeter hollow concretions and voids in Gale Crater sediments, Mars

Voids and hollow spheroids between ∼1 and 23 cm in diameter occur at several locations along the traverse of the Curiosity rover in Gale crater, Mars. These hollow spherical features are significantly different from anything observed in previous landed missions. The voids appear in dark-toned, rough-textured outcrops, most notably at Point Lake (sols 302-305) and Twin Cairns Island (sol 343). Point Lake displays both voids and cemented spheroids in close proximity; other locations show one or the other form. The spheroids have 1-4 mm thick walls and appear relatively dark-toned in all cases, some with a reddish hue. Only one hollow spheroid (Winnipesaukee, sol 653) was analyzed for composition, appearing mafic (Fe-rich), in contrast to the relatively felsic host rock. The interior surface of the spheroid appears to have a similar composition to the exterior with the possible exceptions of being more hydrated and slightly depleted in Fe and K. Origins of the spheroids as Martian tektites or volcanic bombs appear unlikely due to their hollow and relatively fragile nature and the absence of in-place clearly igneous rocks. A more likely explanation to both the voids and the hollow spheroids is reaction of reduced iron with oxidizing groundwater followed by some re-precipitation as cemented rind concretions at a chemical reaction front. Although some terrestrial concretion analogs are produced from a precursor siderite or pyrite, diagenetic minerals could also be direct precipitates for other terrestrial concretions. The Gale sediments differ from terrestrial sandstones in their high initial iron content, perhaps facilitating a higher occurrence of such diagenetic reactions

Spatial Learning Depends on Both the Addition and Removal of New Hippocampal Neurons

The role of adult hippocampal neurogenesis in spatial learning remains a matter of debate. Here, we show that spatial learning modifies neurogenesis by inducing a cascade of events that resembles the selective stabilization process characterizing development. Learning promotes survival of relatively mature neurons, apoptosis of more immature cells, and finally, proliferation of neural precursors. These are three interrelated events mediating learning. Thus, blocking apoptosis impairs memory and inhibits learning-induced cell survival and cell proliferation. In conclusion, during learning, similar to the selective stabilization process, neuronal networks are sculpted by a tightly regulated selection and suppression of different populations of newly born neurons

The Incidence of AIDS-Defining Illnesses at a Current CD4 Count ≥200 Cells/µL in the Post-Combination Antiretroviral Therapy Era

The incidence of AIDS was higher in patients with a current CD4 count of 500-749 cells/µL compared to 750-999 cells/µL, but did not decrease further at higher CD4 levels. Results were similar in those virologically suppressed on combination antiretroviral therapy, suggesting immune reconstitution is incomplete until CD4 >750/µ

Substitutions et independance de systemes de numeration

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 83876 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

EXERTION DURING UPHILL, LEVEL AND DOWNHILL WALKING WITH AND WITHOUT HIKING POLES

This study examined the effects of poles when walking on the rate of perceived exertion (RPE), physiological and kinematics parameters, and upon the mean ratio between locomotor and respiratory rhythms. Twelve healthy male and female volunteers, aged 22 to 49 years old, completed on a motorized treadmill in a counterbalanced randomized order 12 walking trials for 10 min at an individually preferred walking speed, with three grades (horizontal level, uphill or downhill with a slope of 15%), with and without hiking poles and a load carriage of 15% of body mass. During all testing sessions, heart rate (HR), oxygen consumption (VO2), ventilation (VE), tidal volume (VT), breathing frequency (Bf), and stride frequency were recorded continuously during the last 5-min of each trial. At the end of each trial, subjects were asked to give RPE. Energy cost (EC) and VE increased significantly with the grade (-15% < 0% < +15%) and with the carrying load. VT was significantly less important with hiking poles, while Bf was significantly more elevated. VO2 and EC increased (p < 0.05) with the use of the hiking poles only during the downhill trials. No significant effect of poles was observed on HR, RPE, and preferred walking speed. The average ratio between the locomotor and respiratory frequencies was significantly influenced by the three experimental factors tested. There was a significant relationship between average ratio of leg movement per breath and EC of walking among all conditions (r = 0.83, n = 12). These results suggest that the use of the hiking poles had a significant influence on the respiratory and energetic responses only during downhill walkin

Study of the activity of phosphorous acid as a phosphorus plant fertilizer.

Phosphite's capacity to offset phosphorus deficiency was studied on tomato plants through four trials. Different application methods of phosphite (foliar or root) were studied in a nutrient film technique (NFT) disposal, providing optimum conditions for changes to feeding (starvation or nourishment). The ecophysiological approach aimed to characterise the growth and development of plants by the production of dry matter and the formation of the leaf surface, according to environmental conditions during the exponential phase. The results obtained on leaf symptoms and aerial growth emphasize that phosphite is unable to replace phosphate as a phosphorus nutrient, when applied either as a foliar spray or by incorporation in the nutrient solution. What is more, its use on phosphorus deficient plants negatively affects root growth, which is detrimental in case of mineral deficiency. However phosphite does not affect aerial and root growth when plants are normally fed with phosphate

Study of the activity of phosphorous acid as a phosphorus plant fertilizer.

La prestation de recherches faisant l'objet de ce rapport a été demandée par Rhône-Poulenc (RP) comme argument scientifique dans le procès qui l'opposait aux USA à des concurrents qui vendaient des spécialités à base de phosphite (composé actif du fongicide nommé "Alliette" que produit RP), qu'ils vendaient en tant qu'engrais phosphoré en se servant d'un brevet en ce sens déposé par une phytopathologie de l'Université de Davis.RP a gagné son procès et a largement diffusé le présent rapport aux USA, en particulier auprès des organismes de développement agricole.Phosphite's capacity to offset phosphorus deficiency was studied on tomato plants through four trials. Different application methods of phosphite (foliar or root) were studied in a nutrient film technique (NFT) disposal, providing optimum conditions for changes to feeding (starvation or nourishment). The ecophysiological approach aimed to characterise the growth and development of plants by the production of dry matter and the formation of the leaf surface, according to environmental conditions during the exponential phase. The results obtained on leaf symptoms and aerial growth emphasize that phosphite is unable to replace phosphate as a phosphorus nutrient, when applied either as a foliar spray or by incorporation in the nutrient solution. What is more, its use on phosphorus deficient plants negatively affects root growth, which is detrimental in case of mineral deficiency. However phosphite does not affect aerial and root growth when plants are normally fed with phosphate

Translational Modeling of Anticancer Efficacy to Predict Clinical Outcomes in a First-in-Human Phase 1 Study of MDM2 Inhibitor HDM201

We report on a retrospective model-based assessment of the predictive value of translating antitumor drug activity from in vivo experiments to a phase I clinical study in cancer patients treated with the MDM2 inhibitor, HDM201. Tumor growth inhibition models were developed describing the longitudinal tumor size data in human-derived osteosarcoma xenograft rats and in 96 solid tumor patients under different HDM201 treatment schedules. The model structure describing both datasets captures the delayed drug effect on tumor growth via a series of signal transduction compartments, including a resistance component. The models assumed a drug-killing effect on both sensitive and resistant cells and parameterized to estimate two tumor static plasma drug concentrations for sensitive (TSCS) and resistant cells (TSCR). No change of TSCS and TSCR with schedule was observed, implying that antitumor activity for HDM201 is independent of treatment schedule. Preclinical and clinical model-derived TSCR were comparable (48 ng/mL vs. 74 ng/mL) and demonstrating TSCR as a translatable metric for antitumor activity in clinic. Schedule independency was further substantiated from modeling of clinical serum growth differentiation factor-15 (GDF-15) as a downstream marker of p53 pathway activation. Equivalent cumulative induction of GDF-15 was achieved across schedules when normalized to an equivalent total dose. These findings allow for evaluation of optimal dosing schedules by maximizing the total dose per treatment cycle while mitigating safety risk with periods of drug holiday. This approach helped guide a phase I dose escalation study in the selection of an optimal dose and schedule for HDM201