3,101 research outputs found
Constitutional Problems of Population Control
An analysis of the urgency and magnitude of the population problem would show that both national and human survival depend on limiting man\u27s incredible ability to procreate. The world\u27s resources are finite; man\u27s consumption of them must be made so, too, or Malthus\u27 four horsemen will balance the supply and demand for us. If we are not to starve our grandchildren, to leave them with no immunity to the pestilence of overcrowding and hopelessness, to kill them with pollution, or to force war upon them as the only way to secure enough territory to feed a voracious population, we must take decisive action to limit their numbers now
Internal Versus External for Small Weapons Systems
The acquisition method used to gain access to new technologies can heavily influence whether our war fighters have the required tools to fight increasing and constantly shifting global threats (Kessler and others, 2000). The purpose of this study was to investigate the process and results of internal laboratory development, testing and fielding of small weapons systems as compared to traditionally acquired systems which encourage customer pull and contractor development. This research provides insight into how Air Force Research Laboratory (AFRL) personnel choose an acquisition method, retain personnel capability, and maximize product capability. This study consolidates the opinions of subject matter experts and program managers through a wide range of interviewees within AFRL. Data analysis and extensive literature review led to conclusions such as: it is believed that there is no difference in war fighter capability and delivery between internally and externally developed systems; and internal efforts provide better personnel capability, but the current status quo is sufficient. It was also revealed that a majority of AFRL personnel feel pressure to always develop externally. Recommendations include that: AFRL foster an environment where the best acquisition method for the government is chosen; AFRL design an internal contract plan to keep internal efforts on target; and AFRL invest in further concurrent development efforts
A New Fully Implicit in Time Two-Dimensional Inverse Heat Conduction Method
A new combination of methods used to solve the transient, two-dimensional inverse heat conduction problem (IHCP) is presented in this thesis. A simple implicit in time with space marching approach is used in combination with digital filtering for regularization. Results are presented for both one-dimensional and two-dimensional problems. As much as 10% measurement error is added to the data to simulate experimental results.
One-dimensional results with “perfect” data suggested that refining the spatial and temporal meshes improved the accuracy of the inverse solution. However, the nodal Fourier number was found to have no effect on accuracy. Further investigation into the effect of the Fourier number on the inverse solution led to the discovery of a precisely defined stability criterion, which is presented for the one-dimensional problem.
The digital filter was proven to be a highly effective regularization method for both the one-dimensional and two-dimensional cases. The Gauss low pass filter employed a cutoff frequency as the regularization parameter, which has an exact definition with physical significance. No trial and error method of choosing a regularization parameter was necessary. Temperature and heat flux data were given at the sensor sites, noise was added to the data, filtered, and used as input data to the inverse code. The prediction error resulting from the use of “perfect” data suggested a bias (over-prediction). With this bias removed from the noisy, filtered results, the inverse solution was accurate to 2% for the 1D case and 3% for the 2D case. The dramatic reduction of error through an inverse process was striking, since the inverse problem is well-known to magnify measurement errors.
An additional case using only one line of temperature data and no heat flux data was used as alternate approach to the inverse problem. The new strategy relies on a recently developed integral relationship between the heating rate and the heat flux, which is valid on the half-space. The relationship allows for the heat flux to be found at the sensor site using only temperature and heating rate data. This data could be experimentally obtained using one line of thermocouples combined with numerical differentiation to obtain the heating rate; no heat flux gauges or second series of thermocouples are necessary. This thesis is the first to take advantage of heat flux – heating rate relationship. Results from this method with a measurement error of 5% predicted a surface heat flux error of only 5%
Orthologs of the small RPB8 subunit of the eukaryotic RNA polymerases are conserved in hyperthermophilic Crenarchaeota and "Korarchaeota"
Although most of the key components of the transcription apparatus, and in particular, RNA polymerase (RNAP) subunits, are conserved between archaea and eukaryotes, no archaeal homologs of the small RPB8 subunit of eukaryotic RNAP have been detected. We report that orthologs of RPB8 are encoded in all sequenced genomes of hyperthermophilic Crenarchaeota and a recently sequenced "korarchaeal" genome, but not in Euryarchaeota or the mesophilic crenarchaeon Cenarchaeum symbiosum. These findings suggest that all 12 core subunits of eukaryotic RNAPs were already present in the last common ancestor of the extant archaea
Nitrous oxide in fresh water systems: An estimate for the yield of atmospheric N2O associated with disposal of human waste
The N2O content of waters in the Potomac and Merrimack Rivers was measured on a number of occasions over the period April to July 1977. The concentrations of dissolved N2O exceeded those which would apply in equilibrium with air by factors ranging from about 46 in the Potomac to 1.2 in the Merrimack. Highest concentrations of dissolved N2O were associated with sewage discharges from the vicinity of Washington, D. C., and analysis indicates a relatively high yield, 1.3 to 11%, for prompt conversion of waste nitrogen to N2O. Measurements of dissolved N2O in fresh water ponds near Boston demonstrated that aquatic systems provide both strong sources and sinks for atmospheric N2O
On the Method to Infer an Atmosphere on a Tidally-Locked Super Earth Exoplanet and Upper limits to GJ 876d
We develop a method to infer or rule out the presence of an atmosphere on a
tidally-locked hot super Earth. The question of atmosphere retention is a
fundamental one, especially for planets orbiting M stars due to the star's
long-duration active phase and corresponding potential for stellar-induced
planetary atmospheric escape and erosion. Tidally-locked planets with no
atmosphere are expected to show a Lambertian-like thermal phase curve, causing
the combined light of the planet-star system to vary with planet orbital phase.
We report Spitzer 8 micron IRAC observations of GJ 876 taken over 32
continuous hours and reaching a relative photometric precision of 3.9e-04 per
point for 25.6 s time sampling. This translates to a 3 sigma limit of 5.13e-05
on a planet thermal phase curve amplitude. Despite the almost photon-noise
limited data, we are unable to conclusively infer the presence of an atmosphere
or rule one out on the non-transiting short-period super Earth GJ 876d. The
limiting factor in our observations was the miniscule, monotonic photometric
variation of the slightly active host M star, because the partial sine wave due
to the planet has a component in common with the stellar linear trend. The
proposed method is nevertheless very promising for transiting hot super Earths
with the James Webb Space Telescope and is critical for establishing
observational constraints for atmospheric escape.Comment: Published in Ap
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