10,739 research outputs found
Fragmentation of Agricultural Land Parcels
This study seeks to take fragmentation research in a new direction by looking at exurban sprawl and fragmentation of ownership. The primary objective of this study is to identify the location and magnitude of fragmentation of agricultural land parcels sold in Oklahoma. This was accomplished by estimating two different models. The first model regressed a polynomial in time to determine whether or not fragmentation has been increasing over time. While it was hypothesized that parcel size was decreasing, this was not found to be the case. Over the 40 years of data, parcel size was found to only have decreased by one acre. The purpose of the second model was to verify whether or not a location premium exists for small parcels. It was found that a location premium does exist for smaller parcels with parcels in urban counties more likely to receive a premium than those located in more rural counties.fragmentation, land values, parcel size, Production Economics,
DEACON: An Integrated Approach to the Analysis and Design of Enterprise Architecture-Based Computer Networks
The most common approach to network development in the modern organization remains an undocumented, ad hoc method of deploying available technology rapidly to fit within a given cost structure. Current methods largely ignore the importance of integrating the networking strategy of a firm with the overall information systems architecture of the enterprise. To address this problem, a new approach to network analysis and design is presented. The new method integrates existing principles of information systems analysis and design with the unique requirements imposed by distributed systems. The integrated approach seeks to provide the organization with a set of guidelines for allocating resources to a computer network based upon the business goals of a firm. Specifically, the method calls for (1) defining the business problem, (2) modeling business requirements, (3) modeling location requirements, (4) developing a network architecture, (5) simulating network operation, and (6) implementing the network. The method is illustrated and compared to other network development methods. DEACON is found to be an advantageous approach
Characteristics of System Requirements for Electronic Commerce
This paper outlines some critical characteristics of requirements for developing a system designed to support electronic commerce. The characteristics are based not only on traditional user and organizational needs and goals, but also on specific requirement issues that arise in developing network systems and applications for electronic commerce. We then illustrate how an commercial electronic commerce system satisfies the proposed characteristics. A longer version of the paper is available
Critical Team Composition Issues for Long-Distance and Long-Duration Space Exploration: A Literature Review, an Operational Assessment, and Recommendations for Practice and Research
Prevailing team effectiveness models suggest that teams are best positioned for success when certain enabling conditions are in place (Hackman, 1987; Hackman, 2012; Mathieu, Maynard, Rapp, & Gilson, 2008; Wageman, Hackman, & Lehman, 2005). Team composition, or the configuration of member attributes, is an enabling structure key to fostering competent teamwork (Hackman, 2002; Wageman et al., 2005). A vast body of research supports the importance of team composition in team design (Bell, 2007). For example, team composition is empirically linked to outcomes such as cooperation (Eby & Dobbins, 1997), social integration (Harrison, Price, Gavin, & Florey, 2002), shared cognition (Fisher, Bell, Dierdorff, & Belohlav, 2012), information sharing (Randall, Resick, & DeChurch, 2011), adaptability (LePine, 2005), and team performance (e.g., Bell, 2007). As such, NASA has identified team composition as a potentially powerful means for mitigating the risk of performance decrements due to inadequate crew cooperation, coordination, communication, and psychosocial adaptation in future space exploration missions. Much of what is known about effective team composition is drawn from research conducted in conventional workplaces (e.g., corporate offices, production plants). Quantitative reviews of the team composition literature (e.g., Bell, 2007; Bell, Villado, Lukasik, Belau, & Briggs, 2011) are based primarily on traditional teams. Less is known about how composition affects teams operating in extreme environments such as those that will be experienced by crews of future space exploration missions. For example, long-distance and long-duration space exploration (LDSE) crews are expected to live and work in isolated and confined environments (ICEs) for up to 30 months. Crews will also experience communication time delays from mission control, which will require crews to work more autonomously (see Appendix A for more detailed information regarding the LDSE context). Given the unique context within which LDSE crews will operate, NASA identified both a gap in knowledge related to the effective composition of autonomous, LDSE crews, and the need to identify psychological and psychosocial factors, measures, and combinations thereof that can be used to compose highly effective crews (Team Gap 8). As an initial step to address Team Gap 8, we conducted a focused literature review and operational assessment related to team composition issues for LDSE. The objectives of our research were to: (1) identify critical team composition issues and their effects on team functioning in LDSE-analogous environments with a focus on key composition factors that will most likely have the strongest influence on team performance and well-being, and 1 Astronaut diary entry in regards to group interaction aboard the ISS (p.22; Stuster, 2010) 2 (2) identify and evaluate methods used to compose teams with a focus on methods used in analogous environments. The remainder of the report includes the following components: (a) literature review methodology, (b) review of team composition theory and research, (c) methods for composing teams, (d) operational assessment results, and (e) recommendations
Neutrino Oscillations as a Probe of Dark Energy
We consider a class of theories in which neutrino masses depend significantly
on environment, as a result of interactions with the dark sector. Such theories
of mass varying neutrinos (MaVaNs) were recently introduced to explain the
origin of the cosmological dark energy density and why its magnitude is
apparently coincidental with that of neutrino mass splittings. In this Letter
we argue that in such theories neutrinos can exhibit different masses in matter
and in vacuum, dramatically affecting neutrino oscillations. Both long and
short baseline experiments are essential to test for these interactions. As an
example of modifications to the standard picture, we consider simple models
which may simultaneously account for the LSND anomaly, KamLAND, K2K and studies
of solar and atmospheric neutrinos, while providing motivation to continue to
search for neutrino oscillations in short baseline experiments such as BooNE.Comment: 5 pages, 1 figure, refs added, additional data considered, minor
change in conclusions about LSN
Spectro-temporal and Type I X-ray burst analysis of GX 31 using AstroSat observations
GX 31, an atoll type neutron star low-mass X-ray binary, was observed four
times by Soft X-ray Telescope and The Large Area X-ray Proportional Counters
on-board \textit{AstroSat} between October 5, 2017 and August 9, 2018. The
hardness-intensity-diagram of the source showed it to be in the soft spectral
state during all the four observations. The spectra of the source could be
adequately fit with a model consisting of blackbody () and
power-law () components. This yielded the blackbody radius
and mass accretion rate to be 8 km and 2
M y, respectively. In one of the observations, a Type I X-ray
burst having a rise and e-folding time of 0.6 and 5.6 s, respectively, was
detected. Time-resolved spectral analysis of the burst showed that the source
underwent a photospheric radius expansion. The radius of the emitting blackbody
in GX 31 and its distance were estimated to be 9.19
km and 10.17 kpc,
respectively. Temporal analysis of the burst yielded upper limits of the
fractional RMS amplitude of 7, 5 and 6 during burst start, burst
maximum and right after the radius expansion phase, respectively
NuSTAR and AstroSat observations of GX 91: Spectral and temporal studies
We have studied the spectro-temporal properties of the neutron star low mass
X-ray binary GX 91 using data from \textit{NuSTAR/FPM} and
\textit{AstroSat/SXT} and \textit{LAXPC}. The hardness-intensity diagram of the
source showed it to be in the soft spectral state during both observations.
\textit{NuSTAR} spectral analysis yielded an inclination angle ()
29 and inner disk radius () 19.01 km.
Assuming that the accretion disk was truncated at the Alfv\'en radius during
the observation, the upper limit of the magnetic dipole moment () and the
magnetic field strength () at the poles of the neutron star in GX 91 were
calculated to be 1.45 G cm and 2.08 G,
respectively (for 1). Flux resolved spectral analysis with
\textit{AstroSat} data showed the source to be in the soft spectral state
(/ 0.9) with a monotonic increase in mass accretion
rate () along the banana branch. The analysis also showed the presence
of absorption edges at 1.9 and 2.4 keV, likely due to Si XIII and S
XV, respectively. Temporal analysis with \textit{LAXPC-20} data in the 0.02
100 Hz range revealed the presence of noise components, which could be
characterized with broad Lorentzian components
Inferring the Origin Locations of Tweets with Quantitative Confidence
Social Internet content plays an increasingly critical role in many domains,
including public health, disaster management, and politics. However, its
utility is limited by missing geographic information; for example, fewer than
1.6% of Twitter messages (tweets) contain a geotag. We propose a scalable,
content-based approach to estimate the location of tweets using a novel yet
simple variant of gaussian mixture models. Further, because real-world
applications depend on quantified uncertainty for such estimates, we propose
novel metrics of accuracy, precision, and calibration, and we evaluate our
approach accordingly. Experiments on 13 million global, comprehensively
multi-lingual tweets show that our approach yields reliable, well-calibrated
results competitive with previous computationally intensive methods. We also
show that a relatively small number of training data are required for good
estimates (roughly 30,000 tweets) and models are quite time-invariant
(effective on tweets many weeks newer than the training set). Finally, we show
that toponyms and languages with small geographic footprint provide the most
useful location signals.Comment: 14 pages, 6 figures. Version 2: Move mathematics to appendix, 2 new
references, various other presentation improvements. Version 3: Various
presentation improvements, accepted at ACM CSCW 201
Acute military psychiatric casualties from the war in Iraq
Background: The view that most military personnel evacuated from war zones are suffering from combat stress reactions, or are otherwise traumatised by the horrors of war, has an impact on all aspects of military psychiatry.
Aims: To delineate the reasons for psychiatric aeromedical evacuation from Iraq from the start of build-up of UK forces in January 2003 until the end of October that year, 6 months after the end of formal hostilities.
Method: A retrospective study was conducted of field and in-patient psychiatric assessments of 116 military personnel evacuated to the UK military psychiatric in-patient facility in Catterick Garrison.
Results: Evacuees were mainly non-combatants (69%). A significant proportion were in reserve service (21%) and had a history of contact with mental health services (37%). Only 3% had a combat stress reaction. In over 85% of cases evacuation was for low mood attributed to separation from friends or family, or difficulties adjusting to the environment.
Conclusions: These findings have implications especially for screening for suitability for deployment, and for understanding any longer-term mental health problems arising in veterans from Iraq
The Far-Infrared/Radio Correlation in Nearby Abell Clusters
A comprehensive study of the effect of the cluster environment on the far-
infrared (FIR)/radio correlation in nearby Abell clusters is presented. Using
the cluster radio galaxy database from Miller & Owen (2001) and optical
spectroscopy and high resolution radio images to remove AGN, we assess the
FIR/radio correlation of cluster galaxies from the centers of the clusters out
well past the classical Abell radius. The FIR/radio correlation is shown to
hold quite well for star forming galaxies, and the FIR and radio fluxes for
cluster AGN are also well correlated. In the case of AGN, the relative radio-
to-FIR fluxes are greater and the scatter in the correlation is larger than
those seen for star forming galaxies. We also find that there is a rare but
statistically significant excess of star forming galaxies with enhanced radio
emission in the centers of the clusters, and that the degree of this
enhancement is typically a factor of two or three. The FIR/radio correlation
for cluster star forming galaxies is also tested against line-of-sight velocity
relative to the cluster systemic velocities, but no significant correlation is
found. While the radial dependence of the FIR/radio correlation is consistent
with the model wherein ram pressure increases the cluster galaxies' magnetic
field strengths through compression, the velocity data do not confirm this
model. Although a contribution from ram pressure can not be ruled out, the
thermal pressure due to the ICM alone is an equally viable alternative. The
high resolution radio images largely reject the hypothesis that the increased
radio emission arises from an AGN component, strengthening the claim that the
change in the correlation is caused by a change in the environment of the
galaxies.Comment: 26 pages, including 5 figures (uses AASTeX 5.0). Accepted for
publication in the Astronomical Journa
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