599 research outputs found
The Strategic Thought of Paul H. Nitze
Of the many individuals who have helped shape the theory and practice of American national security policy in the post-World War II era, few have had as continuing an influence as Paul H. Nitze. Even a partial listing of his achievements is enough to demonstrate the degree of his importance: The principal author of the 1946 Summary Report (Pacific War) to the United States Strategic Bombing Survey (USSBS), he produced one of the seminal works on the strategic implications of nuclear weapons
The Missions of the Indian Navy
Since the advent of the first oil crisis, the United States and its allies have recognized the strategic importance of the Persian Gulf-Indian Ocean area, The second oil crisis. followed by the seizure of American diplomats in Iran, and then by the Iranian-lraqi War, reinforced the importance of this area in Western minds. Along with increased Western interest, American and allied defense analysts began to focus their attention on military developments within the important oil-producing countries of Iran, Iraq, Saudi Arabia, and Kuwait
Dynamical Effects of Ionospheric Conductivity on the Formation of Polar Cap Arcs
By using a magnetosphere-ionosphere (M-I) coupling model of polar cap arcs [Zhu et al., 1993], a systematic model study of the effects of ionospheric background conductivity on the formation of polar cap arcs has been conducted. The variations of the ionospheric background conductivity in the model study cover typical ionospheric conditions, including solar minimum, solar maximum, winter, and summer. The simulation results clearly indicate that the ionospheric background conductivity can dynamically affect the mesoscale features of polar cap arcs through a nonlinear M-I coupling process associated with the arcs
Mouse models of preterm birth: Suggested assessment and reporting guidelines
Preterm birth affects approximately 1 out of every 10 births in the United States, leading to high rates of mortality and long-term negative health consequences. To investigate the mechanisms leading to preterm birth so as to develop prevention strategies, researchers have developed numerous mouse models of preterm birth. However, the lack of standard definitions for preterm birth in mice limits our field\u27s ability to compare models and make inferences about preterm birth in humans. In this review, we discuss numerous mouse preterm birth models, propose guidelines for experiments and reporting, and suggest markers that can be used to assess whether pups are premature or mature. We argue that adoption of these recommendations will enhance the utility of mice as models for preterm birth
Refilling of Geosynchronous Flux Tubes as Observed at the Equator by GEOS 2
During periods of extended quiet geomagnetic activity the geosynchronous satellite orbit lies inside the plasmasphere. Five such periods were observed by the GEOS 2 satellite. During the initial 48 hours of such periods the equatorial plasma flux tube density increases at 30 to 50 cm−3/day. However, on reaching ∼100 cm−3 the refilling rate decreases, and refilling is limited. Only when the density reaches ∼100 cm−3 do the plasma characteristics and fluctuations appear to be plasmaspheric and the flow predominantly corotational. The “hot outer zone” of the plasmasphere is highly structured in density and temperature when viewed from a corotating satellite. This region also has a relatively dense population of warm subkilovolt electrons. These warm electrons whose density is ∼1% to 50% of the cold plasma may be the heat source for the hot outer zone ions
Validation Study of the Ionospheric Forecast Model Using the TOPEX TEC Measurements
As a part of the validation program in the Utah State University Global Assimilation of Ionospheric Measurement (GAIM) project, a newly improved Ionosphere Forecast Model (IFM) was systematically validated by using a large database of TOPEX total electron content (TEC) measurements. The TOPEX data used for the validation are for the period from August 1992 to March 2003, and the total number of 18-s averaged data is close to 11 million. This model validation work covers a wide range of seasonal (winter, summer, and equinox) and solar (low-F 10.7, median F 10.7, and high-F 10.7) conditions as well as all UT variations with the focus on nonstorm time TEC. The validation results indicate that the features of the spatial distribution of the IFM TEC are systematically consistent with those of the TOPEX TEC. The differences between the IFM TEC and the TOPEX TEC are within 20% for almost all locations and conditions. For many conditions, the differences are even below 10%
Multiple Polar Cap Arcs: Akebono (Exos D) Observations
Akebono (Exos D) observations demonstrate that polar cap arcs sometimes have a fine structure, that is, multiple (double or triple) arcs with spacing of a few tens of kilometers. The multiple polar cap arcs are dominantly observed in the nightside polar cap region, suggesting that low background conductance favors the appearance of the structured arcs. A relationship between the spacing and the average energy of the precipitating electrons is investigated. Results show that a higher energy leads to a wider spacing. Akebono observations also show the existence of a downward current region embedded between upward current regions (arcs). Comparison of the observations with results from a coupled magnetosphere-ionosphere Sun-aligned arc model is made, which shows good qualitative agreement between the modeling and observational results on the spacing-energy dependence and the effect of background ionospheric conductance
Removal of Nonconstant Daily Variation by Means of Wavelet and Functional Data Analysis
We propose a novel approach based on wavelet and functional principal component analysis to produce a cleaner index of the intensity of the symmetric ring current. We use functional canonical correlations to show that the new approach more effectively extracts symmetric global features. The main result of our work is the construction of a new index, which is an improved version of the existing wavelet-based index (WISA) and the old Dst index, in which a constant daily variation is removed. Here, we address the fact that the daily component varies from day to day and construct a “cleaner” index by removing nonconstant daily variations
Sprinkler irrigation runoff and erosion control with polyacrylamide - laboratory tests
Many semiarid and arid soils are prone to irrigation-induced erosion.
Polyacrylamide (PAM) greatly reduces erosion from furrow
irrigation. We hypothesized that PAM applied via sprinklers will
provide erosion control and benefit water infiltration and aggregate
stability. Screened (6.4 mm) Rad silt loam (coarse silty, mixed, superactive
mesic Durinodic Xeric Haplocambid) was placed in 1.5 by 1.2
by 0.2 m steel boxes with 2.4% slope. An oscillating nozzle, 3 m above
the soil, produced a median drop size of 1.2 mm diameter. We applied
0, 1, 2, 4, and 6 kg ha-1 PAM in 20 mm of water in the first irrigation,
followed by two 20-mm water-only irrigations. In a second test, we
applied 0, 2, and 4 kg ha-1 PAM in 8 mm of water in the first irrigation,
followed by two 20-mm water-only irrigations. Two kilograms per
hectare PAM in the first 20-mm irrigation reduced runoff 70% and
soil loss 75% compared to control. Polyacrylamide in 8 mm of water
was less effective. Polyacrylamide in the 20-mm irrigation did not
affect tension infiltration; PAM in the 8-mm irrigation doubled tension
infiltration following the third irrigation. Wet aggregate stability following
the first irrigation was greater in all PAM treatments than on
the check. With 2 kg ha-1 PAM in the 20-mm irrigation, it was 55%;
in 8 mm, 77%. Polyacrylamide applied in the first irrigation at low rates
effectively reduced runoff and erosion. Erosion was more effectively
controlled than runoff
Magnetic field topology during July 14–16 2000 (Bastille Day) solar CME event
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95295/1/grl15382.pd
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