408 research outputs found
Real time targeting for GPS guided weapons using the on-board systems of the F-14D Super Tomcat
Precision Strike has been the central doctrine of the Air Warfare Commanders of the U.S. Navy since this capability was demonstrated and proven during the month long air campaign of Desert Storm. Effectiveness analysis immediately following that conflict showed that natural and man made obscurations of targets, such as clouds and smoke, made precision targeting from the air impossible with laser guided munitions during an alarming percentage of attack missions. In order to attack a target with a laser guided precision weapon, the striking aircraft had to maintain an unobstructed line of sight until weapon impact in order to provide continuous laser energy on the target. To solve this dilemma, a requirement was set forth that demanded an all weather through the clouds precision attack capability. This requirement is being fulfilled by a bevy of new generation weapon systems that are collectively known as GPS guided weapons. These weapons are programmed with target location coordinates and navigate autonomously to the impact point after the aircraft release by using on board inertial navigation computers aided by Global Positioning Satellite technology. Subsequent military operations have employed these new generation GPS guided weapons with great success against fixed targets A significant deficiency has arisen however with GPS guided weapons in attacking relocatable targets. These targets include mobile missile systems, command and control vehicles, and troop convoys, and usually make up more than seventy percent of the overall target list. While the Navy is currently upgrading the F-14D Super Tomcats with the capability to employ GPS guided weapons, the aircraft does not have the capability of using its own sensors as a source of target coordinates. Therefore, if the intended target moves between the time it is located and the time that it is attacked, the GPS guided weapons will miss their mark. This study summarizes the F-14D weapon system and its capabilities and deficiencies in order to form a basis for improved GPS guided weapon targeting. It proposes three possible sources of accurate targeting information that the F-14D can provide to the GPS guided weapons, and outlines a test and evaluation procedure to verify the integrity and airworthiness of proposed avionics and software modifications, as well as a method to employ a systems approach to determine the capability of the F-14D precision strike system to accurately self-target for GPS guided weapons
The Plight of the Monarch Butterfly (Danaus plexippus)
In recent years, the Monarch butterfly population has declined significantly along with their host plant where they lay their eggs, milkweed. Another plant, the sacred fir, which is native to Mexico, has also been on the decline due to climate change. This recent decrease is due to many factors including extreme weather events, insecticides, pesticides, and habitat loss/fragmentation. Recent studies have pointed out that a protection zone around milkweed plants has been shown to alleviate the pressure presented by these chemicals which decrease egg laying efficiency. This study aims to highlight the importance of pollinators, increasing monarch and milkweed populations by tracking and rearing them
Reapportionment, Regional Politics and Partisan Gains
Geographers and demographers have been analyzing U.S. regional population change for decades. From the perspective of politics and governance, understanding these population changes over time is very important because seats in the House of Representatives are reapportioned every decade in accordance with the U.S. Constitution. Representation in the House, in turn, affects the distribution of votes in the Electoral College and thus the impact of regional population change affects the presidency as well as the Congress. As political geographers we have studied the possible impacts of this population change on elections, issues in Congress and the nation, and if a particular political party has gained or lost in the process. This article is adapted from our recently published co-edited book, Atlas of the 2012 Elections, which examines both short-term and long-term state and regional gains and losses in the House of Representatives and Electoral College to see how the Democrats and Republicans have fared
Gender differences in V˙O2 and HR kinetics at the onset of moderate and heavy exercise intensity in adolescents
The majority of the studies on (V)over dotO(2) kinetics in pediatric populations investigated gender differences in prepubertal children during submaximal intensity exercise, but studies are lacking in adolescents. The purpose of this study was to test the hypothesis that gender differences exist in the (V)over dotO(2) and heart rate (HR) kinetic responses to moderate (M) and heavy (H) intensity exercise in adolescents. Twenty-one healthy African-American adolescents (9 males, 15.8 +/- 1.1 year; 12 females, 15.7 +/- 1 year) performed constant work load exercise on a cycle ergometer at M and H. The (V)over dotO(2) kinetics of the male group was previously analyzed (Lai et al., Appl. Physiol. Nutr. Metab. 33:107-117, 2008b). For both genders, (V)over dotO(2) and HR kinetics were described with a single exponential at M and a double exponential at H. The fundamental time constant (tau(1)) of (V)over dotO(2) was significantly higher in female than male at M (45 +/- 7 vs. 36 +/- 11 sec, P < 0.01) and H (41 +/- 8 vs. 29 +/- 9 sec, P < 0.01), respectively. The functional gain (G(1)) was not statistically different between gender at M and statistically higher in females than males at H: 9.7 +/- 1.2 versus 10.9 +/- 1.3 mL min(-1) W-1, respectively. The amplitude of the slow component was not significantly different between genders. The HR kinetics were significantly (tau(1), P < 0.01) slower in females than males at M (61 +/- 16 sec vs. 45 +/- 20 sec, P < 0.01) and H (42 +/- 10 sec vs. 30 +/- 8 sec, P = 0.03). The G(1) of HR was higher in females than males at M: 0.53 +/- 0.11 versus 0.98 +/- 0.2 bpm W-1 and H: 0.40 +/- 0.11 versus 0.73 +/- 0.23 bpm W-1, respectively. Gender differences in the (V)over dotO(2) and HR kinetics suggest that oxygen delivery and utilization kinetics of female adolescents differ from those in male adolescents
Decoration of tricarboxylic and monocarboxylic aryl diazonium functionalized multi-wall carbon nanotubes with iron nanoparticles
Gene copy-number changes and chromosomal instability induced by aneuploidy confer resistance to chemotherapy
Mitotic errors lead to aneuploidy, a condition of karyotype imbalance, frequently found in cancer cells. Alterations in chromosome copy number induce a wide variety of cellular stresses, including genome instability. Here, we show that cancer cells might exploit aneuploidy-induced genome instability and the resulting gene copy-number changes to survive under conditions of selective pressure, such as chemotherapy. Resistance to chemotherapeutic drugs was dictated by the acquisition of recurrent karyotypes, indicating that gene dosage might play a role in driving chemoresistance. Thus, our study establishes a causal link between aneuploidy-driven changes in gene copy number and chemoresistance and might explain why some chemotherapies fail to succeed
Multi-wall Carbon Nanotubes Decorated with Bismuth Oxide Nanocrystals Using Infrared Irradiation and Diazonium Chemistry
A First Look at Spatially Resolved Balmer Decrements at from JWST NIRISS Slitless Spectroscopy
We present the first results on the spatial distribution of dust attenuation
at traced by the Balmer Decrement, H/H, in
emission-line galaxies using deep JWST NIRISS slitless spectroscopy from the
CAnadian NIRISS Unbiased Cluster Survey (CANUCS). H and H
emission line maps of emission-line galaxies are extracted and stacked in bins
of stellar mass for two grism redshift bins, and
. Surface brightness profiles for the Balmer Decrement are
measured and radial profiles of the dust attenuation towards H,
, are derived. In both redshift bins, the integrated
Balmer Decrement increases with stellar mass. Lower mass
(Log(/M)) galaxies have centrally
concentrated, negative dust attenuation profiles whereas higher mass galaxies
(Log(/M)) have flat dust attenuation
profiles. The total dust obscuration is mild, with on average and
mag in the low and high redshift bins respectively. We model the
typical light profiles of star-forming galaxies at these redshifts and stellar
masses with GALFIT and apply both uniform and radially varying dust attenuation
corrections based on our integrated Balmer Decrements and radial dust
attenuation profiles. If these galaxies were observed with typical JWST NIRSpec
slit spectroscopy ( shutters), on average,
H star formation rates (SFRs) measured after slit-loss corrections
assuming uniform dust attenuation will overestimate the total SFR by and at and
respectively.Comment: 7 pages, 5 figures, submitted to ApJ
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