3,163 research outputs found
Application of heat pipes to spacecraft thermal control problems
Application of heat pipes to spacecraft thermal control problem
How Farmers Bid Into the Conservation Reserve Program: An Empirical Analysis of CRP Offers Data
Replaced with revised version of paper 07/19/11.Land Economics/Use,
Continuation of Mourning Dove Studies in Clark County, Arkansas, with Emphasis on Cyclical Behavioral Patterns
In conjunction with the U.S. Department of Interior, Fish and Wildlife Service, the Henderson State University Biology Department has continued a study of mourning doves in Clark County, Arkansas, with emphasis on cyclical behavioral patterns. Three hundred forty-three mourning doves were baited, trapped, and banded to obtain information concerning age, sex, populations, retraps, abnormalities, migrations, trap injuries, cyclical behavioral patterns, and other factors
Analyzing the cost-effectiveness of interventions to benefit orphans and vulnerable children: evidence from Kenya and Tanzania
This item is archived in the repository for materials published for the USAID supported Orphans and Vulnerable Children Comprehensive Action Research Project (OVC-CARE) at the Boston University Center for Global Health and Development
Observation of Coherently-Enhanced Tunable Narrow-Band Terahertz Transition Radiation from a Relativistic Sub-Picosecond Electron Bunch Train
We experimentally demonstrate the production of narrow-band (% at THz) THz transition radiation with tunable
frequency over [0.37, 0.86] THz. The radiation is produced as a train of
sub-picosecond relativistic electron bunches transits at the vacuum-aluminum
interface of an aluminum converter screen. We also show a possible application
of modulated beams to extend the dynamical range of a popular bunch length
diagnostic technique based on the spectral analysis of coherent radiation.Comment: 3 pages, 6 figure
A methodology for evaluating force protection during a computer aided exercise
The development of a proficient staff at the Joint Level is primarily accomplished through the use of computer aided exercises CAXs). The primary purpose of these exercises is to increase the readiness of the staff to perform actual missions from standing up a Joint Task Force (JTF) to redeployment of the forces. A measure of the tasks required of a staff is accomplished through a Mission Essential Task List from the Universal Joint Task List (JTL,). This document defines critical events and activities that must be accomplished to achieve the desired mission goals. The measurement of that performance from actual data from the computer model has been limited. This thesis provides a methodology that assists in the evaluation of force protection. This quantitative analysis can be provided quickly and concurrent to the exercise. Immediate feedback helps the staff and commander to understand why an outcome happened through linkage of JTL tasks. This methodology was tested using the Joint Theater Level Simulation and the results demonstrating the methodology and analysis of the output are presented.http://archive.org/details/methodologyforev00thurCaptain, United States ArmyApproved for public release; distribution is unlimited
Adaptive Coloration in Texas Fiddler Crabs (Uca)
Five species of fiddler crabs occupy a variety of intertidal niches along the Texas coast. Each Uca is adapted to a specific array of physical factors in the environment. Some aspects of their adaptations are reflected by body color. Interspecific differences in morphological coloration are correlated with camouflage and substrate characteristics. Intraspecific color variation is expressed through neurosecretion-mediated physiological change in cellular pigment distribution. Adaptation to a dark or light colored background reveals different secondary chromomotor capabilities for each species. In addition, pigments in melanophores, leucophores and erythrophores exhibit circadian rhythms of dispersion and aggregation.
During a primary chromomotor response to light or temperature, chromatophores act as independent effectors without endocrine mediation. Generally, logarithmic changes in luminosity from 12- to ,000-foot candles disperse chromatophore pigments in species from the Minuca subgenus but not member of the Celuca subgenus. In the very terrestrial Celuca, U. subcylindrica, erythophores and melanophores were observed to aggregate. Since this does not occur in eyestalk-less crabs the response is augmented by light activating a visual-neurosecretory reflex. Changing temperature stimulated thermoregulatory chromomotor activity in the Celuca, U. panacea and U. subcylindrica, but not the Minuca. In Celuca , the carapace darkens as temperature decreases and lightens as it increases. Based on these chromatophore studies, the pigmentary systems of the subgenus Celuca appear to be predisposed for better short-term thermoregulaiton than those in the subgenus Minuca
Mapping the feel of the arm with the sight of the object: on the embodied origins of infant reaching
For decades, the emergence and progression of infant reaching was assumed to be largely under the control of vision. More recently, however, the guiding role of vision in the emergence of reaching has been downplayed. Studies found that young infants can reach in the dark without seeing their hand and that corrections in infants\u27 initial hand trajectories are not the result of visual guidance of the hand, but rather the product of poor movement speed calibration to the goal. As a result, it has been proposed that learning to reach is an embodied process requiring infants to explore proprioceptively different movement solutions, before they can accurately map their actions onto the intended goal. Such an account, however, could still assume a preponderant (or prospective) role of vision, where the movement is being monitored with the scope of approximating a future goal-location defined visually. At reach onset, it is unknown if infants map their action onto their vision, vision onto their action, or both. To examine how infants learn to map the feel of their hand with the sight of the object, we tracked the object-directed looking behavior (via eye-tracking) of three infants followed weekly over an 11-week period throughout the transition to reaching. We also examined where they contacted the object. We find that with some objects, infants do not learn to align their reach to where they look, but rather learn to align their look to where they reach. We propose that the emergence of reaching is the product of a deeply embodied process, in which infants first learn how to direct their movement in space using proprioceptive and haptic feedback from self-produced movement contingencies with the environment. As they do so, they learn to map visual attention onto these bodily centered experiences, not the reverse. We suggest that this early visuo-motor mapping is critical for the formation of visually-elicited, prospective movement control
Recommended from our members
Biostratigraphy, depositional environments, and paleogeography of Lower and Middle Devonian rocks, Death Valley area, California
During Early and Middle Devonian time, the main part of the Death Valley area was characterized by shallow marine shelf position. In the extreme western part, deposition took place in carbonate slope environments. Early and Middle Devonian eastern platform dolomites, represented by uppermost Hidden Valley Dolomite and lower Lost Burro Formation, have been divided into six units in ascending order based on lithology, depositional environment, and age.
The Lochkovian depositional setting was that of southeast to northwest transition from a broad inner platform to a narrow outer shelf basin. Unit 1 intertidal to very shallow subtidal sediments were deposited to the east, whereas a skeletal carbonate bank or reef complex fringing the platform edge supplied bioclastic material to extreme
slope areas to the west. Late Lochkovian regression exposed extreme southeast thesis platform areas to erosion. A depositional hiatus marks the top of farther seaward Unit 1 platform areas in the northern Panamint Range. Unit 2 fossiliferous sediments were widely deposited throughout the thesis area during early Pragian transgression. Unit 2 correlative Sevy-like deposits in southeast areas at Bat Mountain and the Nopah Range mark the landward extent of initial marine onlap during this time. With increased input of clastic material into the normal marine environment, the Unit 2 lithotope was gradually replaced by Unit 3 silty and cherty argillaceous dolomites. The lower part of Unit 3 was deposited during continued marine transgression. The upper part reflects shallowing upward conditions and initiation of late Early Devonian regression. To the west, slope areas contain cherty argillaceous
limestones correlative to Unit 3 and, similarly, indicate shallowing conditions. A beach-barrier bar complex, represented by sandy Unit 4 rocks, prograded seaward over nearshore Unit 3 sediments in response to marine offlap in late Early Devonian time. Unit 4 reflects an increased clastic sediment supply derived from erosion of cratonward strata, as well as marking regression. The seaward prograding sandy environment was followed and progressively overstepped by eastern intertidal-supratidal deposits, represented by Unit S coarse crystalline dolomite. Thinness and gradational lower contact of this lithology suggest that the transgressive part of coarse crystalline dolomite deposition seen in central Nevada may not be present in southeast California.
Deposition of Unit 6 intertidal to shallow subtidal sediments during early Middle Devonian time records a gradual submergence of inner shelf regions by initial transgression. Rocks overlying Unit 6 in the thesis area reflect the larger transgressive pulse of the Taghanic onlap. Two distinct dolomite types are recognizable in the thesis area. Primary dolomite, represented by aphanitic, thinly laminated dolomite at the Nopah Range and Bat Mountain, was formed by penecontemporaneous replacement of
calcareous sediment essentially at time of deposition. This dolomite type preserved microcrystalline textures, and fine sedimentary structures. The second dolomite type, eogenetic secondary dolomite, represents postdepositional near-surface
replacement of limy sediments by slow growth and coalescence of dolomite crystals. This dolomite type characterizes the bulk of the carbonate interval studied. A favored mechanism for eogenetic secondary dolomite formation in the thesis area is that of mixing zone dolomitization, whereby meteoric
freshwater mixes with intrastratal sea water in a seaward extending subsurface wedge. This dolomitizing zone moved seaward with marine regression and landward during transgression,
leaving behind a blanket of dolomitized strata. Coarse crystalline dolomite in Unit 5 was extensively subjected to this paleogeographic-related dolomitizing environment
- …