1,215 research outputs found
No evidence of extraterrestrial noble metal and helium anomalies at Marinoan glacial termination
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Earth and Planetary Science Letters 437 (2016): 76-88, doi:10.1016/j.epsl.2015.12.040.High concentrations of extraterrestrial iridium have been reported in terminal Sturtian and
Marinoan glacial marine sediments and are used to argue for long (likely 3-12 Myr) durations of
these Cryogenian glaciations. Reanalysis of the Marinoan sedimentary rocks used in the original
study, supplemented by sedimentary rocks from additional terminal Marinoan sections, however,
does not confirm the initial report. New platinum group element concentrations, and 187Os/188Os and 3He/4He signatures are consistent with crustal origin and minimal extraterrestrial
contributions. The discrepancy is likely caused by different sample masses used in the two
studies, with this study being based on much larger samples that better capture the stochastic
distribution of extraterrestrial particles in marine sediments. Strong enrichment of redox-sensitive elements, particularly rhenium, up-section in the basal postglacial cap carbonates, may
indicate a return to more fully oxygenated seawater in the aftermath of the Marinoan snowball
earth. Sections dominated by hydrogenous osmium indicate increasing submarine hydrothermal
sources and/or continental inputs that are increasingly dominated by young mantle-derived rocks
after deglaciation. Sedimentation rate estimates for the basal cap carbonates yield surprisingly
slow rates of a few centimeters per thousand years. This study highlights the importance of
using sedimentary rock samples that represent sufficiently large area-time products to properly
sample extraterrestrial particles representatively, and demonstrates the value of using multiple
tracers of extraterrestrial matter.We are grateful for support from a 2008 WHOI Summer Student Fellowship for CAW. BPE
acknowledges financial support from WHOI’s Ocean and Climate Change Institute (CH11320)
and U.S. NSF SGER grant EAR-0821878. Fieldwork in NW Canada was licensed by the Aurora
Research Institute and supported by a grant to PFH from the Astrobiology Institute of the US
National Aeronautics and Space Administration (NASA). Fieldwork in NW Canada and
Namibia was supported by grants EAR-9905495 and EAR-0417422 (to PFH) from the US NSF.
We thank Jon Husson (Harvard University) and Ricardo Trindade (University of São Paulo,
Brazil) for excellent support during fieldwork in Namibia in August of 2005
Examining the influence of task set on eye movements and fixations
The purpose of the present study was to examine the influence of task set on the spatial and temporal characteristics of eye movements during scene perception. In previous work, when strong control was exerted over the viewing task via specification of a target object (as in visual search), task set biased spatial, rather than temporal, parameters of eye movements. Here, we find that more participant-directed tasks (in which the task establishes general goals of viewing rather than specific objects to fixate) affect not only spatial (e.g., saccade amplitude) but also temporal parameters (e.g., fixation duration). Further, task set influenced the rate of change in fixation duration over the course of viewing but not saccade amplitude, suggesting independent mechanisms for control of these parameters
The Effects of God Language on Perceived Attributes of God
Sixty-three participants listened to an audio· tape asking them to imagine themselves in God\u27s presence. Half the participants listened to a script in which God was presented as female and half listened to a script in which God was presented as male. Half of those in each group listened to a male narrator and the other half listened to a female narrator. Before and after listening to the script, participants rated the attributes of God on a forced-choice questionnaire. Those to whom God was presented as female were more likely to emphasize God\u27s mercy at posttest whereas those to whom God was presented as male were more likely to endorse God\u27s power. Those hearing a male voice describe a female God and those hearing a female voice describe a male God reported enjoying the experiment and the audiotape more than those hearing a narrator describing a God of the same gender. Implications are discussed
Rootless cones on Mars indicating the presence of shallow equatorial ground ice in recent times
Low Fuel Convergence Path to Direct-Drive Fusion Ignition
A new class of inertial fusion capsules is presented that combines multishell targets with laser direct drive at low intensity (2.8×10¹⁴ W/cm²) to achieve robust ignition. The targets consist of three concentric, heavy, metal shells, enclosing a volume of tens of μg of liquid deuterium-tritium fuel. Ignition is designed to occur well “upstream” from stagnation, with minimal pusher deceleration to mitigate interface Rayleigh-Taylor growth. Laser intensities below thresholds for laser plasma instability and cross beam energy transfer facilitate high hydrodynamic efficiency (∼10%)
Intra-tumor L-methionine level highly correlates with tumor size in both pancreatic cancer and melanoma patient-derived orthotopic xenograft (PDOX) nude-mouse models.
An excessive requirement for methionine (MET) for growth, termed MET dependence, appears to be a general metabolic defect in cancer. We have previously shown that cancer-cell growth can be selectively arrested by MET restriction such as with recombinant methioninase (rMETase). In the present study, we utilized patient-derived orthotopic xenograft (PDOX) nude mouse models with pancreatic cancer or melanoma to determine the relationship between intra-tumor MET level and tumor size. After the tumors grew to 100 mm3, the PDOX nude mice were divided into two groups: untreated control and treated with rMETase (100 units, i.p., 14 consecutive days). On day 14 from initiation of treatment, intra-tumor MET levels were measured and found to highly correlate with tumor volume, both in the pancreatic cancer PDOX (p<0.0001, R2=0.89016) and melanoma PDOX (p<0.0001, R2=0.88114). Tumors with low concentration of MET were smaller. The present results demonstrates that patient tumors are highly dependent on MET for growth and that rMETase effectively lowers tumor MET
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The combination of temozolomide-irinotecan regresses a doxorubicin-resistant patient-derived orthotopic xenograft (PDOX) nude-mouse model of recurrent Ewing's sarcoma with a FUS-ERG fusion and CDKN2A deletion: Direction for third-line patient therapy.
The aim of the present study was to determine the usefulness of a patient-derived orthotopic xenograft (PDOX) nude-mouse model of a doxorubicin-resistant metastatic Ewing's sarcoma, with a unique combination of a FUS-ERG fusion and CDKN2A deletion, to identify effective drugs for third-line chemotherapy of the patient. Our previous study showed that cyclin-dependent kinase 4/6 (CDK4/6) and insulin-like growth factor-1 receptor (IGF-1R) inhibitors were effective on the Ewing's sarcoma PDOX, but not doxorubicin, similar to the patient's resistance to doxorubicin. The results of the previous PDOX study were successfully used for second-line therapy of the patiend. In the present study, the PDOX mice established with the Ewing's sarcoma in the right chest wall were randomized into 5 groups when the tumor volume reached 60 mm3: untreated control; gemcitabine combined with docetaxel (intraperitoneal [i.p.] injection, weekly, for 2 weeks); irinotecan combined with temozolomide (irinotecan: i.p. injection; temozolomide: oral administration, daily, for 2 weeks); pazopanib (oral administration, daily, for 2 weeks); yondelis (intravenous injection, weekly, for 2 weeks). All mice were sacrificed on day 15. Body weight and tumor volume were assessed 2 times per week. Tumor weight was measured after sacrifice. Irinotecan combined with temozolomide was the most effective regimen compared to the untreated control group (p=0.022). Gemcitabine combined with docetaxel was also effective (p=0.026). Pazopanib and yondelis did not have significant efficacy compared to the untreated control (p=0.130, p=0.818). These results could be obtained within two months after the physician's request and were used for third-line therapy of the patient
Concept Design of High Power Solar Electric Propulsion Vehicles for Human Exploration
Human exploration beyond low Earth orbit will require enabling capabilities that are efficient, affordable and reliable. Solar electric propulsion (SEP) has been proposed by NASA s Human Exploration Framework Team as one option to achieve human exploration missions beyond Earth orbit because of its favorable mass efficiency compared to traditional chemical propulsion systems. This paper describes the unique challenges associated with developing a large-scale high-power (300-kWe class) SEP vehicle and design concepts that have potential to meet those challenges. An assessment of factors at the subsystem level that must be considered in developing an SEP vehicle for future exploration missions is presented. Overall concepts, design tradeoffs and pathways to achieve development readiness are discussed
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Recombinant methioninase combined with doxorubicin (DOX) regresses a DOX-resistant synovial sarcoma in a patient-derived orthotopic xenograft (PDOX) mouse model.
Synovial sarcoma (SS) is a recalcitrant subgroup of soft tissue sarcoma (STS). A tumor from a patient with high grade SS from a lower extremity was grown orthotopically in the right biceps femoris muscle of nude mice to establish a patient-derived orthotopic xenograft (PDOX) mouse model. The PDOX mice were randomized into the following groups when tumor volume reached approximately 100 mm3: G1, control without treatment; G2, doxorubicin (DOX) (3 mg/kg, intraperitoneal [i.p.] injection, weekly, for 2 weeks; G3, rMETase (100 unit/mouse, i.p., daily, for 2 weeks); G4 DOX (3mg/kg), i.p. weekly, for 2 weeks) combined with rMETase (100 unit/mouse, i.p., daily, for 2 weeks). On day 14 after treatment initiation, all therapies significantly inhibited tumor growth compared to untreated control, except DOX: (DOX: p = 0.48; rMETase: p < 0.005; DOX combined with rMETase < 0.0001). DOX combined with rMETase was significantly more effective than both DOX alone (p < 0.001) and rMETase alone (p < 0.05). The relative body weight on day 14 compared with day 0 did not significantly differ between any treatment group or untreated control. The results indicate that r-METase can overcome DOX-resistance in this recalcitrant disease
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