20,837 research outputs found
Development of a 25 - 50 watt high efficiency, X-band, traveling wave tube Quarterly report, Nov. 1970 - Jan. 1971
Computer design technique of electron gun for use in spacecraft transmitter
Optimization of controlled environments for hydroponic production of leaf lettuce for human life support in CELSS
A research project in the food production group of the Closed Ecological Life Support System (CELSS) program sought to define optimum conditions for photosynthetic productivity of a higher plant food crop. The effects of radiation and various atmospheric compositions were studied
The origin of non-classical effects in a one-dimensional superposition of coherent states
We investigate the nature of the quantum fluctuations in a light field created by the superposition of coherent fields. We give a physical explanation (in terms of Wigner functions and phase-space interference) why the 1-D superposition of coherent states in the direction of the x-quadrature leads to the squeezing of fluctuations in the y-direction, and show that such a superposition can generate the squeezed vacuum and squeezed coherent states
Managing Codling Moth (Lepidoptera: Tortricidae) with an Internal Grid of Either Aerosol Puffers or Dispenser Clusters Plus Border Applications of Individual Dispensers
Field trials run from 2001 to 2003 evaluated the effectiveness of a combination of handapplied sex pheromone dispensers (Isomate-C) applied on the perimeter of apple orchards with an internal grid of either pressurized aerosol emitters (puffers) or clusters of dispensers for control of codling moth, Cydia pomonella (L.). Puffers were placed in a grid at 1 per ha, while the dispenser clusters were applied at 4 - 8 per ha. Puffers were programmed to release either 240 or 360 mg (E, E)-8-10-dodecadienol (codlemone) per day in 48 puffs (every 15 min from 1500 – 0300 h). Dispensers were grouped in clusters of 50 (Isomate-C TT) or 100 (Isomate-C PLUS) releasing 56 and 33 mg codlemone per d, respectively. No significant differences were found in levels of fruit injury in puffertreated orchards paired with similar orchards treated with 500 Isomate-C PLUS individually applied dispensers per ha. Similarly no significant differences in fruit injury were found in orchards treated with individually applied dispensers versus orchards treated with Isomate-C PLUS dispensers (100 per cluster) placed in screened cages or Isomate-C TT dispensers (50 per cluster) hung from plastic disks. Levels of fruit injury, however, were significantly higher in orchards treated with Isomate-C PLUS dispensers (100 per cluster) hung from plastic disks versus in orchards treated with individually applied dispensers. This later poor performance of the Isomate-C PLUS clusters was associated with its more restricted spacing of dispensers within the cluster and a significant reduction in the weight loss of dispensers compared with dispensers applied individually. These studies suggest that the use of puffers can effectively lower the cost of codling moth management through reductions in sex pheromone puff volume and emitter density
Stem cell mechanobiology
Stem cells are undifferentiated cells that are capable of proliferation, self-maintenance and differentiation towards specific cell phenotypes. These processes are controlled by a variety of cues including physicochemical factors associated with the specific mechanical environment in which the cells reside. The control of stem cell biology through mechanical factors remains poorly understood and is the focus of the developing field of mechanobiology. This review provides an insight into the current knowledge of the role of mechanical forces in the induction of differentiation of stem cells. While the details associated with individual studies are complex and typically associated with the stem cell type studied and model system adopted, certain key themes emerge. First, the differentiation process affects the mechanical properties of the cells and of specific subcellular components. Secondly, that stem cells are able to detect and respond to alterations in the stiffness of their surrounding microenvironment via induction of lineage-specific differentiation. Finally, the application of external mechanical forces to stem cells, transduced through a variety of mechanisms, can initiate and drive differentiation processes. The coalescence of these three key concepts permit the introduction of a new theory for the maintenance of stem cells and alternatively their differentiation via the concept of a stem cell 'mechano-niche', defined as a specific combination of cell mechanical properties, extracellular matrix stiffness and external mechanical cues conducive to the maintenance of the stem cell population.<br/
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CitySCaPE: Moving beyond indifference in education for pre-registration nurses about learning disability
People with learning disabilities and Autism continue to suffer from the delivery of ineffective and inadequate care from health services CitySCaPE (City Simulated Community and Practice Environment) is a multi media resource delivering a simulation of situations student nurses may encounter in relation to service users with learning disabilities. The resource is applicable to adult, mental health and children's nursing. It is delivered in a blended approach to students in the first part of their programme as part of their simulated practice. Following the implementation of the resource an evaluation of student experience was undertaken using a mixed methods approach. 146 responses were obtained to a questionnaire containing quantitative and qualitative data. The findings indicate that this is a pedagogy that suits a variety of learning styles, is deemed to be realistic and improves the understanding of nursing students about the care of people with learning disabilities in generic practice areas. It is anticipated that CitySCaPE can be used as a model for delivery of practice based learning in areas that are often challenging to teach and demonstrate using a service user and person centred approach
Long time deviation from exponential decay: non-integral power laws
Quantal systems are predicted to show a change-over from exponential decay to
power law decay at very long times. Although most theoretical studies predict
integer power-law exponents, recent measurements by Rothe et al. of decay
luminescence of organic molecules in solution {Phys. Rev. Lett. 96 (2006)
163601} found non-integer exponents in most cases. We propose a physical
mechanism, within the realm of scattering from potentials with long tails,
which produces a continuous range of power law exponents. In the tractable case
of the repulsive inverse square potential, we demonstrate a simple relation
between the strength of the long range tail and the power law exponent. This
system is amenable to experimental scrutiny
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