Spatially Explicit Representation of State-and-Transition Models     

Caitriana M. Steele  Brandon T. Bestelmeyer  Laura M. Burkett  Philip L. Smith  Steven Yanoff 《Strength and Conditioning Journal》2012,65(3):213-222

The broad-scale assessment of natural resource conditions (e.g., rangeland health, restoration needs) requires knowledge of their spatial distribution. We argue that creating a database that links state-and-transition models (STMs) to spatial units is a valuable management tool for structuring ground-based observations, management planning for landscapes, and for housing information on the responses of land areas to management actions. To address this need, we introduce a multifactor classification system based on ecological sites and STMs that is directly linked to recent concepts of vegetation dynamics in rangelands. We describe how this classification was used as a basis for creating a spatial database and maps of ecological states. We provide an example of how the classification and mapping has been applied in over 1.2 million ha of public rangelands in southern New Mexico using aerial photo interpretation supplemented with existing inventory data and rapid field assessments. The resulting state map has been used by the Bureau of Land Management: 1) to design landscape-level shrub control efforts, 2) to structure and report district-wide rangeland health assessments, and 3) to evaluate locations for energy development. We conclude by discussing options for the development of state maps and their current limitations, including the use of satellite imagery and concepts for defining states. We argue that cataloging ecological states in a spatial context has clear benefits for rangeland managers because it connects STM concepts to specific land areas. State mapping provides a means to generate and store spatially explicit data resulting from tests of the propositions in STMs and conservation practices.  相似文献   

Mapping land cover in urban residential landscapes using very high spatial resolution aerial photographs     

Salman Al-Kofahi  Caiti Steele  Dawn VanLeeuwen  Rolston St. Hilaire 《Urban Forestry & Urban Greening》2012,11(3):291-301

Accurate information on existing residential landscapes is essential for framing ordinances and monitoring residential water use in the Urban Greenspace Ecosystem. We classified residential landscapes of New Mexico's largest city, Albuquerque, to explore the spatial distribution of residential greenspace and its composition among zip codes and median incomes. Geographic Information System (GIS) vector files including parcels, city limits, zip codes and land-use maps, were integrated with ownership information. The database was stratified by Albuquerque's 16 zip codes. Four hundred eighty residential landscapes were selected randomly for study. Very high spatial resolution (0.15 m) 2008 true color aerial photographs and the object-oriented supervised classification module in ENVI EX were used to identify residential features. Spatial and textural variables, created by image segmentation, were classified using the K-Nearest Neighbor (K-NN) algorithm embedded in ENVI EX. Classification accuracy was 89%. Larger greenspace, tree, shrub, and grass areas were in larger parcels. Landscapes in lower income groups and older zip codes include larger greenspace and tree cover because of mature tree sizes, while grass dominated landscapes of higher income groups and newer zip codes. This knowledge of residential vegetation distribution could serve as a basis for policy makers, planners, and water conservation officers wishing to enact ordinances and regulations that govern the urban residential landscape.  相似文献   

Bioequivalence of a new liquid formulation of benazepril compared with the reference tablet product     

K Kelers  JL Devi  GA Anderson  P Zahra  JH Vine  T Whittem 《Australian veterinary journal》2013,91(8):312-319

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Fungi isolated from bovine udders,and their possible sources     

JH Williamson  ME di Menna 《New Zealand veterinary journal》2013,61(4):188-190

AIM: To identify fungi isolated from infections of the bovine mammary gland, and establish their possible sources.

METHODS: From a herd of 420 cows, milk samples were collected from all quarters at calving and cultured to detect causative organisms. Quarters identified as infected with fungi were further sampled during early lactation. Samples from feedstuffs, the feed pad and ends of teats were also collected and analysed for the presence of fungi.

RESULTS: Eleven of 420 cows were diagnosed with intramammary infections (IMI) caused by yeasts (nine cows, 10 quarters) and moulds (two cows, three quarters). Six of the yeast species had previously been reported as being responsible for mastitis. Elevated somatic cell counts (SCC) were observed in many quarters, but most infections were eliminated spontaneously. Two of the fungi isolated from milk samples were also isolated from feedstuffs and teat swabs, and seven other fungi isolated from milk samples were not isolated from feed, the feed pad or cows' teats.

CONCLUSIONS: Isolation of fungi from the udder is rarely reported in dairy cows in New Zealand. In this herd, contamination of the end of the teat originating from feedstuffs and possibly exacerbated by the use of a feed pad may have led to the establishment of IMI caused by fungi.

CLINICAL RELEVENCE: Fungi are infrequently if ever reported in mastitis trial data or surveys in New Zealand and are probably of little clinical significance.  相似文献   

Veterinary public health: past success, new opportunities     

Steele JH 《Preventive veterinary medicine》2008,86(3-4):224-243

Animal diseases are known to be the origin of many human diseases, and there are many examples from ancient civilizations of plagues that arose from animals, domesticated and wild. Records of attempts to control zoonoses are almost as old. The early focus on food-borne illness evolved into veterinary medicine's support of public health efforts. Key historical events, disease outbreaks, and individuals responsible for their control are reviewed and serve as a foundation for understanding the current and future efforts in veterinary public health. Animal medicine and veterinary public health have been intertwined since humans first began ministrations to their families and animals. In the United States, the veterinary medical profession has effectively eliminated those major problems of animal health that had serious public health ramifications. These lessons and experiences can serve as a model for other countries. Our past must also be a reminder that the battle for human and animal health is ongoing. New agents emerge to threaten human and animal populations. With knowledge of the past, coupled with new technologies and techniques, we must be vigilant and carry on.  相似文献   

Synthesis of large arrays of well-aligned carbon nanotubes on glass     

ZF Ren  ZP Huang  JW Xu  JH Wang  P Bush  MP Siegal  PN Provencio 《Science (New York, N.Y.)》1998,282(5391):1105-1107

Free-standing aligned carbon nanotubes have previously been grown above 700 degreesC on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666 degreesC by plasma-enhanced hot filament chemical vapor deposition. Acetylene gas was used as the carbon source and ammonia gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0. 1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.  相似文献   

Localization of metastable atom beams with optical standing waves: nanolithography at the heisenberg limit     

KS Johnson  JH Thywissen  NH Dekker  KK Berggren  AP Chu  R Younkin  M Prentiss 《Science (New York, N.Y.)》1998,280(5369):1583-1586

The spatially dependent de-excitation of a beam of metastable argon atoms, traveling through an optical standing wave, produced a periodic array of localized metastable atoms with position and momentum spreads approaching the limit stated by the Heisenberg uncertainty principle. Silicon and silicon dioxide substrates placed in the path of the atom beam were patterned by the metastable atoms. The de-excitation of metastable atoms upon collision with the surface promoted the deposition of a carbonaceous film from a vapor-phase hydrocarbon precursor. The resulting patterns were imaged both directly and after chemical etching. Thus, quantum-mechanical steady-state atom distributions can be used for sub-0.1-micrometer lithography.  相似文献   

An approximately 15,000-year record of El Nino-driven alluviation in southwestern ecuador     

DT Rodbell  GO Seltzer  DM Anderson  MB Abbott  DB Enfield  JH Newman 《Science (New York, N.Y.)》1999,283(5401):516-520

Debris flows have deposited inorganic laminae in an alpine lake that is 75 kilometers east of the Pacific Ocean, in Ecuador. These storm-induced events were dated by radiocarbon, and the age of laminae that are less than 200 years old matches the historic record of El Nino events. From about 15,000 to about 7000 calendar years before the present, the periodicity of clastic deposition is greater than or equal to 15 years; thereafter, there is a progressive increase in frequency to periodicities of 2 to 8.5 years. This is the modern El Nino periodicity, which was established about 5000 calendar years before the present. This may reflect the onset of a steeper zonal sea surface temperature gradient, which was driven by enhanced trade winds.  相似文献   

Ruminal acidosis and the rapid onset of ruminal parakeratosis in a mature dairy cow: a case report     

Michael A Steele  Ousama AlZahal  Sarah E Hook  Jim Croom  Brian W McBride 《Acta veterinaria Scandinavica》2009,51(1):39

A mature dairy cow was transitioned from a high forage (100% forage) to a high-grain (79% grain) diet over seven days. Continuous ruminal pH recordings were utilized to diagnose the severity of ruminal acidosis. Additionally, blood and rumen papillae biopsies were collected to describe the structural and functional adaptations of the rumen epithelium. On the final day of the grain challenge, the daily mean ruminal pH was 5.41 ± 0.09 with a minimum of 4.89 and a maximum of 6.31. Ruminal pH was under 5.0 for 130 minutes (2.17 hours) which is characterized as the acute form of ruminal acidosis in cattle. The grain challenge increased blood beta-hydroxybutyrate by 1.8 times and rumen papillae mRNA expression of 3-hydroxy-3-methylglutaryl-coenzyme A synthase by 1.6 times. Ultrastructural and histological adaptations of the rumen epithelium were imaged by scanning electron and light microscopy. Rumen papillae from the high grain diet displayed extensive sloughing of the stratum corneum and compromised cell adhesion as large gaps were apparent between cells throughout the strata. This case report represents a rare documentation of how the rumen epithelium alters its function and structure during the initial stage of acute acidosis.  相似文献   

Analysis of the natural infection of European horse chestnut (Aesculus hippocastanum) by Pseudomonas syringae pv. aesculi     

H Steele  B. E Laue  G. A MacAskill  S. J Hendry  S Green 《Plant pathology》2010,59(6):1005-1013

Pseudomonas syringae pv. aesculi (Psa) is an emerging bacterial pathogen responsible for a recent epidemic of bleeding canker of European horse chestnut (Aesculus hippocastanum) in northwest Europe. Very little is known about the infection biology of this pathogen, which can cause lethal cankers in the branches and stem of its host. In this study, branches and whole trees of European horse chestnut naturally infected with Psa were subjected to detailed morphological and histological examination to identify the primary infection sites, the time of infection, and the patterns of subsequent lesion expansion within the host. Lesions developed during the host dormant season on the 2003–2009 extension growth increments and were centred mainly on lenticels, leaf scars and nodes. The oldest lesion developed in the 2004/2005 dormant season and the number of new lesions increased in each subsequent year. The lesions developed in the cortex and phloem and extended into the cambium to cause cankers, but there was no evidence of necrosis in the xylem. All lesions on the branches were discrete and apparently contained by a necrophylactic periderm, although there was evidence that Psa could survive within such periderms and subsequently breach them. Examination of two whole 30‐year‐old trees revealed extensive, continuous cankers in the phloem and cambium which had formed within a single growing season. Thus, the success of Psa as a tree pathogen and the causal agent of a large‐scale epidemic may in part reflect an ability to infect the aerial woody parts of its host directly.  相似文献