440 research outputs found
Nickel hydrogen low Earth orbit test program update and status
The current status of nickel-hydrogen (NiH2) testing ongong at NWSC, Crane In, and The Aerospace Corporation, El Segundo, Ca are described. The objective of this testing is to develop a database for NiH2 battery use in Low Earth Orbit (LEO) and support applications in Medium Altitude Orbit (MAO). Individual pressure vessel-type cells are being tested. A minimum of 200 cells (3.5 in diameter and 4.5 in diameter) are included in the test, from four U.S. vendors. As of this date (Nov. 18, 1986) approximately 60 cells have completed preliminary testing (acceptance, characterization, and environmental testing) and have gone into life cycling
Approximate Jacobians for the Solution of the Euler and Navier-Stokes Equations. G.U. Aero Report 9705
This paper describes a method for efficiently solving the steady-state Euler and Navier-Stokes equations. Robustness is achieved through the use of an upwind TVD scheme for discretising the convective terms. The approximate solution is advanced in time implicitly and the linear system arising at each implicit step is solved using a Conjugate Gradient type method. The main emphasis of this paper is on the use of Jacobian matrices associated with a simpler spatial discretisation. This leads to better conditioned linear systems. The resulting method has lower memory and CPU-time requirements when compared with the one using exact Jacobians
Solution of the Euler Unsteady Equations Using Deforming Grids. G.U. Aero Report 9704.
No abstract available
No meditation-related changes in the auditory N1 during first-time meditation
Recent studies link meditation expertise with enhanced low-level attention, measured through auditory event-related potentials (ERPs). In this study, we tested the reliability and validity of a recent finding that the N1 ERP in first-time meditators is smaller during meditation than non-meditation – an effect not present in long-term meditators. In the first experiment, we replicated the finding in first-time meditators. In two subsequent experiments, we discovered that this finding was not due to stimulus-related instructions, but was explained by an effect of the order of conditions. Extended exposure to the same tones has been linked with N1 decrement in other studies, and may explain N1 decrement across our two conditions. We give examples of existing meditation and ERP studies that may include similar condition order effects. The role of condition order among first-time meditators in this study indicates the importance of counterbalancing meditation and non-mediation conditions in meditation studies that use event-related potentials
Meditation and auditory attention: An ERP study of meditators and non-meditators
The findings of a study by Cahn and Polich (2009) suggests that there is an effect of a meditative state on three event-related potential (ERP) brain markers of “low-level” auditory attention (i.e., acoustic representations in sensory memory) in expert meditators: the N1, the P2, and the P3a. The current study built on these findings by examining trait and state effects of meditation on the passive auditory mismatch negativity (MMN), N1, and P2 ERPs. We found that the MMN was significantly larger in meditators than non-meditators regardless of whether they were meditating or not (a trait effect), and that N1 amplitude was significantly attenuated during meditation in non-meditators but not expert meditators (an interaction between trait and state). These outcomes suggest that low-level attention is superior in long-term meditators in general. In contrast, low-level attention is reduced in non-meditators when they are asked to meditate for the first time, possibly due to auditory fatigue or cognitive overload
Banana root and soil health project - Australia
The banana plant forms an adventitious root system that is dependent on soil physical, chemical and biological properties to function efficiently. A pot experiment demonstrated that increasing soil compaction was able to significantly reduce the weight of banana roots and shoots. However, in the presence of Radopholus similis the effects of soil compaction were obscured, due to the significant reduction in root weight caused by the nematode. The use of a basic set of soil quality indicators that can be readily used by farmers, was linked to soil nematode indicators to determine relationships between soil properties. In a survey of banana fields in North Queensland, different diameter root classes were affected differently by changing soil properties. Banana roots greater than 5 mm diameter were positively correlated with aggregate stability and negatively correlated with soil bulk density. Banana roots less than 1 mm were positively correlated with electrical conductivity. Specific interactions between soil properties become apparent as crop production systems become more uniform. This allows farmers to prioritise management options to improve the most deficient soil health indicators. The addition of organic amendments is one possible method of correcting degrading soils. The use of amendments with high carbon contents, such as grass hay, banana trash and lucerne hay, were able to significantly suppress R. similis in the roots of banana plants relative to untreated soil. Due to banana production being located near environmentally sensitive areas there is an increasing need to monitor and modify soil management practices. However, this needs to be linked with a framework that allows the integration of all soil components with a system to allow continual improvement in soil management to allow banana production to have minimal impact on the surrounding environment
Training school teachers to promote mental and social well-being in low and middle income countries : lessons to facilitate scale-up from a participatory action research trial of youth first in India
Mental and social wellbeing (MSWB) promotion programs could improve mental health
and other outcomes for youth in Low and Middle Income Countries (LMICs).
Unfortunately, few such programs have progressed to scale-up and few studies have
detailed processes and considerations that could facilitate doing so. This study begins to
fill these gaps, describing key findings from training and supporting government middle
school teachers to deliver the Youth First Resilience Curriculum, a MSWB promotion
program, in Bihar, India. We conducted a Participatory Action Research trial of the
resilience curriculum among 792 middle school youth and 55 teachers at 15 government
schools. Participant-observations, exit interviews, and group discussions were conducted
and analyzed via multiple rounds of coding to generate thematic findings. A number of
schools showed relatively high levels of interest, session reliability and fidelity, student
interaction and teacher facilitative abilities, but there was great variation within the
sample. Three leverage points emerged to facilitate future scale-up: factors for successful
site assessment and program initiation, supporting teacher success via interest and
motivation, and responding to varied teacher skill levels. These points represent critical
focus areas for practitioners and policy-makers as more MSWB promotion programs
begin to scale in LMICs.peer-reviewe
Development of key soil health indicators for the Australian banana industry
To improve the sustainability and environmental accountability of the banana industry there is a need to develop a set of soil health indicators that integrate physical, chemical and biological soil properties. These indicators would allow banana growers, extension and research workers to improve soil health management practices. To determine changes in soil properties due to the cultivation of bananas, a paired site survey was conducted comparing soil properties under conventional banana systems to less intensively managed vegetation systems, such as pastures and forest. Measurements were made on physical, chemical and biological soil properties at seven locations in tropical and sub-tropical banana producing areas. Soil nematode community composition was used as a bioindicator of the biological properties of the soil. Soils under conventional banana production tended to have a greater soil bulk density, with less soil organic carbon (C) (both total C and labile C), greater exchangeable cations, higher extractable P, greater numbers of plant-parasitic nematodes and less nematode diversity, relative to less intensively managed plant systems. The organic banana production systems at two locations had greater labile C, relative to conventional banana systems, but there was no significant change in nematode community composition. There were significant interactions between physical, chemical and nematode community measurements in the soil, particularly with soil C measurements, confirming the need for a holistic set of indicators to aid soil management. There was no single indicator of soil health for the Australian banana industry, but a set of soil health indicators, which would allow the measurement of soil improvements should include: bulk density, soil C, pH, EC, total N, extractable P, ECEC and soil nematode community structure
The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence
Recently, we showed that the self-field transport critical current, Ic(sf),
of a superconducting wire can be defined in a more fundamental way than the
conventional (and arbitrary) electric field criterion, Ec = 1 microV/cm. We
defined Ic(sf) as the threshold current, Ic,B, at which the perpendicular
component of the local magnetic flux density, measured at any point on the
surface of a high-temperature superconducting tape, abruptly crosses over from
a non-linear to a linear dependence with increasing transport current. This
effect results from the current distribution across the tape width
progressively transitioning from non-uniform to uniform. The completion of this
progressive transition was found to be singular. It coincides with the first
discernible onset of dissipation and immediately precedes the formation of a
measureable electric field. Here, we show that the same Ic,B definition of
critical currents applies in the presence of an external applied magnetic
field. In all experimental data presented here Ic,B is found to be
significantly (10-30%) lower than Ic,E determined by the common electric field
criterion of Ec = 1 microV/cm, and Ec to be up to 50 times lower at Ic,B than
at Ic,E.Comment: 14 pages, 10 figure
- …