3,181 research outputs found

    Combat, supply, and the influence of logistics during the Civil War in Indian Territory.

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    The purpose of this study is to broaden the historical knowledge of the war in Indian Territory by looking at the relationship between combat, supply, and logistics and the progression of warfare in the Territory as a result ... . It chronicles the events in the Civil War in Indian Territory from the withdrawal of federal troops in 1861 through the end of hostilities in 1865

    A Longitudinal Study of Human Exposure to Potential Nuclear Power Plant Risk

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    This study constructs a potential risk index (PRI) for the 65 U.S.-based commercial nuclear power plant (NPP) sites in relation to their surrounding populations. Four risk levels are defined: low risk, moderate risk, high risk, and very high risk. Discrepancies that exist in the sociodemographic characteristics of the host communities’ populations are examined as sorted by risk-level category. It is found that a greater percentage of minority groups are exposed to the highest levels of risk. In addition, percent “Hispanic” and percent “Other,” a grouping that includes multiracial, mixed, interracial, as well as Hispanic and Latino groups (for example, Mexican, Puerto Rican, Cuban, or Spanish) are categories that show the greatest percent change in both the period 1990–2000 and 2000–2010

    A Model for the Evaluation of Lower Extremity Kinematics with Integrated Multisegmental Foot Motion

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    Background/Purpose Current models for assessing lower extremity motion during gait benefit from ease of use in the clinical environment. However, underlying assumptions regarding joint location and distal segment motion limit their effectiveness and accuracy. The aim of this study was to develop a model for lower extremity motion analysis, which integrates functional methods for estimating hip joint center (HJC) location and a multisegmental approach to modeling motion of the foot and ankle. The new model is capable of tracking the motion of six segments (pelvis, bilateral thigh, tibia, hindfoot, forefoot, and hallux) during stance and swing. Methods Ten healthy young adults underwent gait analysis with the new model and two existing standardized models, PlugInGait (PIG) and Milwaukee Foot Model (MFM), and results were compared between models. Results Pointwise correlation results demonstrate good agreement with existing standardized models in several measures; areas of lesser correlation are well-explained by differences in methods of locating joint centers and referencing to the underlying anatomy. Repeatability analysis with the coefficient of multiple correlation (CMC) found values greater than 0.9 for 16 of 18 segment/plane couplets. Discussion Correlation and repeatability analyses suggest the new model is well-suited for clinical and research applications. This model of lower extremity motion with integrated multisegmental foot kinematics will improve clinicians’ ability to characterize patient populations, plan treatment, and monitor progress

    The Morphologies of the Small Magellanic Cloud

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    We compare the distribution of stars of different spectral types, and hence mean age, within the central SMC and find that the asymmetric structures are almost exclusively composed of young main sequence stars. Because of the relative lack of older stars in these features, and the extremely regular distribution of red giant and clump stars in the SMC central body, we conclude that tides alone are not responsible for the irregular appearance of the central SMC. The dominant physical mechanism in determining the current-day appearance of the SMC must be star formation triggered by a hydrodynamic interaction between gaseous components. These results extend the results of population studies (cf. Gardiner and Hatzidimitriou) inward in radius and also confirm the suggestion of the spheroidal nature of the central SMC based on kinematic arguments (Dopita et al; Hardy, Suntzeff & Azzopardi). Finally, we find no evidence in the underlying older stellar population for a ``bar'' or ``outer arm'', again supporting our classification of the central SMC as a spheroidal body with highly irregular recent star formation.Comment: 8 pages, accepted for publication in ApJ Letters (higher quality figures available at http://ngala.as.arizona.edu/dennis/mcsurvey.html

    Quantifying the Drivers of Star Formation on Galactic Scales. I. The Small Magellanic Cloud

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    We use the star formation history of the Small Magellanic Cloud (SMC) to place quantitative limits on the effect of tidal interactions and gas infall on the star formation and chemical enrichment history of the SMC. The coincident timing of two recent (< 4 Gyr) increases in the star formation rate and SMC/Milky Way(MW) pericenter passages suggests that global star formation in the SMC is driven at least in part by tidal forces due to the MW. The Large Magellanic Cloud (LMC) is the other potential driver of star formation, but is only near the SMC during the most recent burst. The poorly constrained LMC-SMC orbit is our principal uncertainty. To explore the correspondence between bursts and MW pericenter passages further, we model star formation in the SMC using a combination of continuous and tidally-triggered star formation. The behavior of the tidally-triggered mode is a strong inverse function of the SMC-MW separation (preferred behavior ~ r^-5, resulting in a factor of ~100 difference in the rate of tidally-triggered star formation at pericenter and apocenter). Despite the success of these closed-box evolutionary models in reproducing the recent SMC star formation history and current chemical abundance, they have some systematic shortcomings that are remedied by postulating that a sizable infall event (~ 50% of the total gas mass) occured about 4 Gyr ago. Regardless of whether this infall event is included, the fraction of stars in the SMC that formed via a tidally triggered mode is > 10% and could be as large as 70%.Comment: Accepted for publication in Ap

    Crustacea of the Cayman Islands, British West Indies. I. Records of Mysids from Shallow Water Non-Reef Habitats

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    A single species of mysid Siriella chierchiae has been previously reported from the Cayman Islands. However, between May 1995 and August 1999, 20 species of mysids were collected from shallow water non-reef habitats surrounding Grand Cayman and Little Cayman Islands. Of the species collected, one species Anchialina typica has a cosmopolitan distribution in tropical and subtropical seas. Thirteen species (Amathimysis cherados, A. gibba, Bowmaniella johnsoni, Dioptromysis paucispinosa, Heteromysis bermudensis, H. mayana, Mysidium columbiae, M. gracile, M. integrum, Mysidopsis bispinulata, M. brattstromi, Parvimysis bahamensis, Siriella chierchiae) are found widely distributed throughout the subtropical and tropical waters of the Northwest Atlantic. Four species (Heteromysis coralina, Mysidopsis mathewsoni, Siriella chessi, S. macrophthalma) previously known only from their type localities are reported, and two undescribed species of Heteromysis, one from Little Cayman Island, and one from Grand Cayman Island, are recognized

    Postoperative Foot and Ankle Kinematics in Rheumatoid Arthritis

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    Introduction Rheumatoid arthritis (RA) is a systemic autoimmune disease that can cause weakening and destruction of various joints of the foot and may result in pain and deformity. This clinical presentation can cause eventual loss of function, shoe-wear difficulties, and altered gait patterns. Purpose The goal of this prospective study was to quantify changes in temporal-spatial parameters and multisegmental foot and ankle kinematics in a group of patients with RA of the forefoot following surgery. Methods Three-dimensional (3-D) motion analysis was conducted preoperatively and postoperatively using a 15-camera Vicon Motion Analysis System (Vicon Motion Systems, Inc.; Lake Forest, CA) on 14 feet in 13 patients with forefoot RA. The Milwaukee foot model was used to characterize segmental kinematics and temporal-spatial parameters. Preoperative and postoperative data were compared using paired nonparametric methods; comparisons with normative data were performed using unpaired nonparametric methods. Results Preoperatively, the hallux was in a valgus position, the forefoot was abducted and in valgus, and range of motion was limited in various phases in all segments. Walking speed and stride length were decreased and stance prolonged when compared with normal controls. Postoperatively, the hallux alignment was restored to normal but a limited range of motion remained. Kinematics also demonstrated forefoot valgus and tibial internal rotation compared with the control population. Comparisons to healthy ambulators also showed decreased stride lengths and prolonged stance phase durations. Conclusion Surgery effectively restored alignment and weight-bearing capacity of the rheumatoid feet. Temporal-spatial parameters and kinematics, however, were not restored to control values, but rather were consistent with first metatarsophalangeal joint fusion effects. The altered mechanics after surgery demonstrate the importance of quantitative assessment in understanding the geometric and kinematic effects of surgical realignment with implications for postoperative rehabilitation and gait training
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