4,480 research outputs found
SMALL FARM POLYPERIOD PLANNING MODEL FOR DEVELOPING ECONOMIES
Farm Management,
Agent-Based Modelling of the Relationships among Kinship, Residence, and Exchange
In the North American Southwest, archaeological research has documented ceramic
exchange networks in which spatially proximate households in consumer
communities have greatly varying amounts of imported pottery. This paper
uses agent-based modelling to gain insight into the processes responsible for
these distributions. The agent-based model used here tracks kinship ties among
agents representing individuals who give birth, marry, co-reside with spouses,
and exchange things in a virtual landscape filled with small settlements of up to
a few hundred individuals. Exchange of goods in the model flows through the
kinship networks. The results suggest that the differential distribution of goods
among spatially proximate households seen in the archaeological cases could
result from a small-world network that forms as some individuals move to join
spouses in far-off settlements, giving relatives in their home settlement preferential
access to exchange goods originating in distant places
BEYOND THE VIOLENCE INDIAN AGRICULTURE, WHITE REMOVAL, AND THE UNLIKELY CONSTRUCTION OF THE NORTHERN CHEYENNE RESERVATION, 1876-1900
Upon first glance, a specific act of violence seemed to fix the particular location of the Northern Cheyenne Reservation. On December 12, 1880, the prominent Northern Cheyenne chief, Little Wolf, staggered into a white-owned trading store near Fort Keogh, Montana Territory, and, in a drunken stupor, shot and killed a fellow Cheyenne named Starving Elk. Enraged at Starving Elk for gambling with his daughter, Little Wolf committed the most atrocious act a Cheyenne could commit, the killing of another Cheyenne. Blood spilled within the tribe polluted the Mahuts, the four sacred arrows the Creator gave to the Cheyenne people to mark them as distinct from other mortals and forever bind them to him.1 As one of the four Old Man Chiefs of the tribe, Little Wolf understood that defiling the Mahuts disrupted the unity between the Cheyenne and their Creator, creating trouble for his people. Immediately sobered and embarrassed, and understanding that custom demanded retribution from Starving Elk\u27s kin, Little Wolf dropped his rifle and reportedly declared, I am going up on that hill by the bend of the creek. If anybody wants me I\u27ll be there.
Virtual Kinship Networks: Exploring Social Networks from an Agent-Based Model
This paper analyzes the structure of virtual kinship networks formed by an
agent-based model that was originally designed to explore the relationships
among kin networks, residence rules, settlement size, and the movement of exchange
goods.Following simple rules, agents in the model are born, die, find
mates, establish post-marital residence. Agents then exchange goods (which are
conceptualized as pottery vessels) among close kin dispersed through a linear
system of villages. Each run of the model produces a network that unites most
agents, but each agent also has a personal network of close kin. Previous analysis
of model output has focused on variation in the number of virtual pottery
vessels obtained by agents, and on data averaged over large numbers of model
runs, with only minimal analysis of the networks produced. But variation
in network structure must underlie the variation in exchange success seen in
the model runs. This paper focuses on the virtual networks produced by the
model, including examining variation in measures of centrality and degree distribution,
as well as variation in path length from one end of the system to the
other. The data exploration reported here indicates that centrality is important,
but centrality alone is not a good predictor of success in exchange. Agents who
obtain large numbers of vessels typically are connected to producers directly
or through one or two intermediate links, and also tend to have relatively high
centrality in the network
Eccentric fatigue modulates stretch-shortening cycle effectiveness - a possible role in lower limb overuse injuries
The role of fatigue in injury development is an important consideration for clinicians. In particular, the role of eccentric fatigue in stretch shortening cycle (SSC) activities may be linked to lower limb overuse conditions. The purpose of this study was to explore the influence of ankle plantarflexor eccentric fatigue on SSC effectiveness during a hopping task in healthy volunteers. 11 healthy volunteers (23.2 ± 6.7 years) performed a sub-maximal hopping task on a custom- built sledge system. 3D motion capture and surface EMG were utilised to measure lower limb stiffness, temporal kinematic measures and muscle timing measures at baseline and immediately following an eccentric fatigue protocol. A linear mixed model was used to test whether measures differed between conditions. Compared to baseline, eccentric fatigue induced increased stiffness during the hopping task (+ 15.3 %; P \u3c 0.001). Furthermore, ankle stretch amplitude decreased (– 9.1 %; P \u3c 0.001), whilst all other ankle kinematic measures remained unchanged. These changes were accompanied by a temporal shift in onset of activity in soleus and tibialis anterior muscles (– 4.6 to – 8.5 %; p \u3c 0.001). These findings indicate that eccentric fatigue alters SSC effectiveness in healthy volunteers. These findings may be applied to inform pathogenetic models of overuse injury development
Quaking Aspen in the Residential-Wildland Interface: Elk Herbivory Hinders Forest Conservation
Quaking aspen (Populus tremuloides Michx.) forests are experiencing numerous impediments across North America. In the West, recent drought, fire suppression, insects, diseases, climate trends, inappropriate management, and ungulate herbivory are impacting these high biodiversity forests. Additionally, ecological tension zones are sometimes created where the above factors intermingle with jurisdictional boundaries. The public-private land interface may result in stress to natural areas where game species find refuge and plentiful forage at the expense of ecosystem function. We examined putative herbivore impacts to aspen forests at Wolf Creek Ranch (WCR), a large residential landscape in northern Utah. Forty-three ha-1 monitoring plots were established to measure a range of attributes summarizing location description, tree and vegetation condition, and herbivore presence. Additionally, we tested the ability of a stand-level visual rating system to represent more detailed field measures. Elk (Cervus elaphus L.) herbivory is currently having a strong effect on aspen in the study area, reducing many locations to single-layer aspen forests dominated by aging canopy trees. Regeneration (\u3c 2 m stems) is experiencing moderate-to-high browse and recruitment (2 - 6 m stems) are below replacement levels on approximately half of WCR\u27s aspen forests. The condition rating system represented significant trends in forest cover, canopy height, stand aspect, regeneration, recruitment, and tree mortality. Ordination of all plot and forest data found a strong negative relationship between elk presence and recruitment success. We make recommendations for addressing difficult herbivore-aspen interactions where publicly managed wildlife a present barriers to conservation of privately owned forest reserves
An HI absorption distance to the black hole candidate X-ray binary MAXI J1535-571
With the Australian Square Kilometre Array Pathfinder (ASKAP) we monitored
the black hole candidate X-ray binary MAXI J1535--571 over seven epochs from 21
September to 2 October 2017. Using ASKAP observations, we studied the HI
absorption spectrum from gas clouds along the line-of-sight and thereby
constrained the distance to the source. The maximum negative radial velocities
measured from the HI absorption spectra for MAXI J1535--571 and an
extragalactic source in the same field of view are km s and
km s, respectively. This rules out the far kinematic distance
( kpc), giving a most likely distance of
kpc, with a strong upper limit of the tangent point at kpc.
At our preferred distance, the peak unabsorbed luminosity of MAXI J1535--571
was per cent of the Eddington luminosity, and shows that the soft-to-hard
spectral state transition occurred at the very low luminosity of 1.2 -- 3.4
10 times the Eddington luminosity. Finally, this study
highlights the capabilities of new wide-field radio telescopes to probe
Galactic transient outbursts, by allowing us to observe both a target source
and a background comparison source in a single telescope pointing.Comment: Revised after favorable referee report from MNRAS Letter
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