2,275 research outputs found
Generating value in program alliances: the value of dialogue in large-scale infrastructure projects
Collaboration forms the backbone of program alliances, with the âpain-gain shareâ regime acting as an incentive to engender behaviours that foster teamwork and trusting relationships to flourish. While dialogue within and between parties in a program alliance has been identified as key to establishing collaboration and trust, there is limited understanding of how it is engendered and maintained to ensure the delivery of superior project outcomes. In filling this void, our paper aims to address the following research question: How does the value of dialogue influence effective collaboration in program alliances? A sense-making lens is adopted to garner an understanding of the value of effective dialogue in two program alliance infrastructure projects. The value and power of dialogue are examined by addressing a recurring problem that negatively impacted the performance of the alliances and their projects: rework. We show that effective dialogue mitigated rework as participants had a shared purpose. Enacting dialogue helped shape the program alliancesâ culture and foster an environment where people felt safe to âspeak upâ. This paperâs contributions are 2-fold as we: (1) unearth new value-laden principles to support dialogue in program alliances; and (2) provide empirical evidence for practitioners to help them understand the value of dialogue in delivering a program of infrastructure projects using an alliance delivery strategy
Financing an Increased State Role in Funding K-12 Education: An Analysis of Issues and Options
This report presents an analysis of replacing school property tax with alternative state revenue sources. FRC Report 11
MESAS: Measuring the Emission of Stellar Atmospheres at Submm/mm wavelengths
In the early stages of planet formation, small dust grains grow to become mm
sized particles in debris disks around stars. These disks can in principle be
characterized by their emission at submillimeter and millimeter wavelengths.
Determining both the occurrence and abundance of debris in unresolved
circumstellar disks of A-type main-sequence stars requires that the stellar
photospheric emission be accurately modeled. To better constrain the
photospheric emission for such systems, we present observations of Sirius A, an
A-type star with no known debris, from the JCMT, SMA, and VLA at 0.45, 0.85,
0.88, 1.3, 6.7, and 9.0 mm. We use these observations to inform a PHOENIX model
of Sirius A's atmosphere. We find the model provides a good match to these data
and can be used as a template for the submm/mm emission of other early A-type
stars where unresolved debris may be present. The observations are part of an
ongoing observational campaign entitled Measuring the Emission of Stellar
Atmospheres at Submm/mm wavelengths (MESAS)Comment: 17 pages, 1 figure, Accepted to AJ on April 25th 201
Saturation front evolution for liquid infiltration into a gas filled porous medium with counter-current flow
Passive, broadband and low-frequency suppression of laser amplitude noise to the shot-noise limit using hollow-core fibre
We use hollow-core fibre to preserve the spectrum and temporal profile of
picosecond laser pulses in CBD to suppress 2.6 dB of amplitude noise at MHz
noise frequencies, to within 0.01 dB of the shot-noise limit. We provide an
enhanced version of the CBD scheme that concatenates circuits to suppress over
multiple frequencies and over broad frequency ranges --- we perform a first
demonstration that reduces total excess amplitude noise, between 2 - 6 MHz, by
85%. These demonstrations enable passive, broad-band, all-guided fibre laser
technology operating at the shot-noise limit.Comment: 8 pages, 8 figure
Understanding wind turbine power converter reliability under realistic wind conditions
The reliability of wind turbine power converters is crucial for analyzing wind energy project costs, and for estimating maintenance and downtime. The published literature in this field relies on evaluating the reliability effect of wind speed to estimate the converter lifetime. However, this paper demonstrates that wind turbulence intensity, which has not been widely considered in similar reliability analyses, shows a significant impact on converter lifetime. This paper uses 821 10âmin wind speed time series sampled at 1 Hz on the two most commonly deployed wind turbine converter topologies: the twoâlevel voltage source and the threeâlevel neutral point clamped. Electromechanical and thermal modelling, combined with statistical analysis shows that mean wind speed and turbulence intensity both impact the lifetime of both converter topologies. However, the paper estimates that the threeâlevel converter can operate 2.4 to 4.0 times longer than the twoâlevel converter depending on the operating wind speed and turbulence intensity
Triggering of a volcanic dome collapse by rainwater infiltration
The thermodynamic processes in a one-dimensional model of a porous lava dome are considered in the presence of a rising magmatic gas flux through the void spaces and rainfall interacting with the dome surface. The steady state surface temperature of the dome depends on both magmatic gas mass flux and rainfall rate. A critical rainfall rate is determined, that cools the dome surface to 100°C. Rainfall rates above this critical value allow liquid infiltration into the void spaces of the dome, thus restricting the escape of magmatic gas. A model which restricts the gas flow through the surface predicts internal gas pressures much higher than the overburden pressure in the top few meters, approximately one hour after the onset of rainfall. For a marginally stable dome, this could cause small Vulcanian explosions, which (depending on their location) could trigger a dome collapse, on a timescale consistent with observations
Feasibility Study for Field Research: Ethnobotany and Ecology of Wild and Cultivated Aroids in Assam State, Northeast India
Over a period of nine days (10-18 November, 2013), the authors conducted discussions, fieldwork and interviews with local researchers, forestry officials, village leaders, and farmers in Guwahati City and Karbi Anglong district, in Assam State, Northeast India. Our aims were to determine the potential, feasibility and practical requirements for ethnobotanical field research and plant collection in the region, with particular regard to cultivated aroids and their wild relatives (Colocasia spp., Alocasia spp., and others). The locations, habitats, abundance, vernacular names, and uses of wild and cultivated aroids were noted. We examined a range of environments in and around Guwahati City, Karbi Anglong (a lowmountain district where swidden farming is still practised), and the large island of Majuli (located in the Brahmaputra River)
Thermal structure of a gas-permeable lava dome and timescale separation in its response to perturbation
The thermal boundary layer at the surface of a volcanic lava dome is investigated through a continuum model of the thermodynamic advection diffusion processes resulting from magmatic gas flow through the dome matrix. The magmatic gas mass flux, porosity and permeability of the rock are identified as key parameters. New, theoretical, nonlinear steady-state thermal profiles are reported which give a realistic surface temperature of 210 degC for a region of lava dome surface through which a gas flux of 3.5 x 10-3 kg s-1 m-2 passes. This contrasts favourably with earlier purely diffusive thermal models, which cool too quickly. Results are presented for time-dependent perturbations of the steady states as a response to: changes in surface pressure, a sudden rockfall from the lava dome surface, and a change in the magmatic gas mass flux at depth. Together with a generalized analysis using the method of multiple scales, this identifies two characteristic time scales associated with the thermal evolution of a dome carapace: a short time scale of several minutes, over which the magmatic gas mass flux, density, and pressure change to a new quasi-steady-state, and a longer time scale of several days, over which the thermal profile changes to a new equilibrium distribution. Over the longer time scale the dynamic properties of the dome continue to evolve, but only in slavish response to the ongoing temperature evolution. In the light of this time scale separation, the use of surface temperature measurements to infer changes in the magmatic gas flux for use in volcanic hazard prediction is discussed
Analysis of the Effect of a Sunscreen Agent on the Suppression of Natural Killer Cell Activity Induced in Human Subjects by Radiation from Solarium Lamps
Previous studies in rodents have shown that ultraviolet radiation (UVR) may have direct effects on the immune system in the skin and at higher doses may induce systemic suppression of immune responses. We have previously shown that UVR from sun or solarium beds may induce systemic effects in human subjects. The purpose of the present study was to examine whether these systemic effects in human subjects could be prevented by use of commercially available sunscreen agents. Groups of 12 normal subjects were exposed to radiation from solarium lamps after application of a sunscreen agent or the base used in its preparation. Twelve half-hourly exposures induced a depression of natural killer (NK) cell activity against a melanoma and the K562 target cell which was not prevented by use of the sunscreen agent. Changes in functional activity were accompanied by a reduction in NK cell numbers assessed by Leu-11 monoclonal antibodies against the labile Fc receptor. Application of the sunscreen agent also did not protect against effects of solarium exposure on recall antigen skin tests and immunoglobulin production in vitro in pokeweed mitogen-stimulated cultures of B and T cells. These results suggest that further evaluation of the wavelength spectrum of UVR and the effectiveness of sunscreen agents in prevention of UVR-induced effects on the immune system is needed
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