Thermoluminescence dates and palaeoenvironmental information of the late Quaternary sand deposits, Tierra de Pinares, Central Spain     

Mark D. Bateman  Andrs Díez Herrero 《CATENA》1999,34(3-4)

A large amount of Quaternary palaeo-environmental evidence lies within the terrestrial aeolian sediments filling the Duero basin in central Spain. Previous work has identified a number of stratigraphical units although the absolute age and origin of some of these is equivocal. The uppermost unit, the focus of this paper, is a widely distributed sand which covers most of the Tierra de Pinares, north of Segovia. Detailed investigations of an exposure at Burgomillodo reveal over 35 m of laminated and cross-bedded sand from which seven thermoluminescence dates were obtained. The bedding structures indicate a northwesterly palaeowind direction, different from the present dominating westerly winds. Two phases of sand deposition are identified at the site with evidence of erosion and reactivation phases. An upper unit of ca. 7 ka during the warm-aridity of the Atlantic period and a lower unit between 12.5–11 ka coinciding with the cold-aridity of the Younger Dryas event. The latter, in which at least 25 m of sand were deposited at the site, is the dominant phase and is coincident with what has been identified elsewhere in Spain from biological data as a period which was both cold and dry. The Burgomillodos site, therefore, represents the first sedimentological evidence for this arid phase in the Younger Dryas in central Spain.  相似文献   

Naturally occurring Mycoplasma bovis-associated pneumonia and polyarthritis in feedlot beef calves.   总被引：1，自引：0，他引：1  

Mihai I Gagea  Kenneth G Bateman  Rachel A Shanahan  Tony van Dreumel  Beverly J McEwen  Susy Carman  Marie Archambault  Jeff L Caswell 《Journal of veterinary diagnostic investigation》2006,18(1):29-40

Mycoplasma bovis is perceived as an emerging cause of mortality in feedlot beef cattle. This study examined the lesions and infectious agents in naturally occurring M. bovis-associated bronchopneumonia and arthritis and the relationship of this condition with bovine viral diarrhea virus (BVDV) infection. Standardized pathologic, immunohistochemical, and microbiologic investigations were conducted on 99 calves that died or were euthanized within 60 days after arrival in 72 feedlots. Cranioventral bronchopneumonia with multiple foci of caseous necrosis was identified in 54 of 99 calves, including 30 with concurrent fibrinosuppurative bronchopneumonia typical of pneumonic pasteurellosis. Mycoplasma bovis was consistently identified in these lesions by culture and immunohistochemistry, but also commonly in healthy lungs and those with pneumonia of other causes. Focal lesions of coagulation necrosis, typical of pneumonic pasteurellosis, were often infected with both Mannheimia haemolytica and M. bovis. Arthritis was present in 25 of 54 (46%) calves with M. bovis pneumonia, and all calves with arthritis had pneumonia. BVDV infection was more common in calves with lesions of bacterial pneumonia than in those dying of other causes, but BVDV infection was not more common in calves with caseonecrotic bronchopneumonia than those with fibrinosuppurative bronchopneumonia. Retrospective analysis identified cases of M. bovis pneumonia in the early 1980s that had milder lesions than the current cases. The findings suggest that, in at least some calves, M. bovis induces caseonecrotic bronchopneumonia within the lesions of pneumonic pasteurellosis.  相似文献   

Effect of Insemination–Ovulation Interval and Addition of Seminal Plasma on Sow Fertility to Insemination of Cryopreserved Sperm     

M Abad  JC Garcia  DJ Sprecher  G Cassar  RM Friendship  MM Buhr  RN Kirkwood 《Reproduction in domestic animals》2007,42(4):418-422

In swine, the use of frozen-thawed (FT) sperm for artificial insemination (AI) is limited because of poor sow fertility, possibly associated with a post-thaw capacitation-like status resulting in fewer fully viable sperm. Sow fertility to AI with FT sperm may improve with deeper deposition of sperm within the female tract, insemination very close to ovulation, or reversal of cryocapacitation by seminal plasma (SP). We performed two experiments to examine these suggestions. In experiment 1, 122 multiparous Yorkshire sows received 600 IU equine chorionic gonadotrophin at weaning and 5 mg pLH 80 h later to control time of ovulation. The predicted time of ovulation (PTO) was 38 h after pLH injection. Thereafter, sows were assigned on the basis of parity to a single AI of FT sperm at 2 h before PTO, or at 12 h before PTO, or FT sperm supplemented with 10% SP at 12 h before PTO. Control sows received fresh semen at 12 h before PTO. All semen doses were adjusted to 3 x 10(9) live cells and deposited into the cervix. Experiment 2 employed 99 multiparous crossbred sows and repeated the treatments of experiment 1 except that all FT inseminations were intrauterine. In both experiments, farrowing rates were lower (p < 0.01) following FT inseminations with no effect of time of insemination or of supplemental SP. In experiment 1, litter size was smaller following FT insemination (p < 0.05), but no effect on litter size was evident in experiment 2. Supplemental SP had no effect on litter size in either experiment. The lack of effect of either SP or timing of FT insemination on sow fertility suggests that the non-lethal sperm cryoinjury affecting fertility involves more than just cryocapacitation.  相似文献   

Brown hyaenas on roads: Estimating carnivore occupancy and abundance using spatially auto-correlated sign survey replicates     

Michelle Thorn  Matthew Green  Philip W. Bateman  Stephen Waite  Dawn M. Scott 《Biological conservation》2011,(6):1799-1807

Carnivore survey protocols that properly address spatial sampling and detectability issues are seldom feasible at a landscape-scale. This limits knowledge of large-scale patterns in distribution, abundance and their underlying determinants, hindering conservation of globally threatened carnivore populations. Occupancy analysis of data from logistically efficient sign surveys along consecutive road segments (spatially auto-correlated replicates) offers a potential solution. We adapted and applied this newly-developed method over 62,979 km² of human-modified land in South Africa. Our aims were to (1) generate unbiased estimates of brown hyaena occupancy and abundance (2) investigate two suspected determinants of occupancy using a combination of biological and socio-economic sampling techniques, and (3) use simulations to evaluate the effort required for abundance and occupancy estimates with acceptable bias, precision and power. Brown hyaena occupancy was estimated at 0.748 (±SE 0.1), and estimated overall density in agricultural land (0.15/100 km², ±SE 0.08) was an order of magnitude lower than in protected areas. Positive attitudes to carnivores and presence of wildlife farms exerted strong positive effects on occupancy, so changes in these factors may well exert monotonic impacts on local metapopulation status. Producing reliable occupancy and abundance estimates would require ?6 replicates and ?12 replicates per site respectively. Detecting 50% and 30% declines in brown hyaena occupancy with adequate power would require five annual surveys at ?65 sites and ?125 sites respectively. Our results suggest that protocols based on spatially auto-correlated sign survey replicates could be used to monitor carnivore populations at large, and possibly even country-wide spatial scales.  相似文献   

Polymorphs of Alumina Predicted by First Principles: Putting Pressure on the Ruby Pressure Scale     

KT Thomson  RM Wentzcovitch  MST Bukowinski 《Science (New York, N.Y.)》1996,274(5294):1880-1882

Fully optimized quantum mechanical calculations indicate that Al2O3 transforms from the corundum structure to the as yet unobserved Rh2O3 (II) structure at about 78 gigapascals, and it further transforms to Pbnm-perovskite structure at 223 gigapascals. The predicted x-ray spectrum of the Rh2O3 (II) structure is similar to that of the corundum structure, suggesting that the Rh2O3 (II) structure could go undetected in high-pressure x-ray measurements. It is therefore possible that the ruby (Cr3+-doped corundum) fluorescence pressure scale is sensitive to the thermal history of the ruby chips in a given experiment.  相似文献   

An Economics Approach to Hard Computational Problems     

BA Huberman  RM Lukose  T Hogg 《Science (New York, N.Y.)》1997,275(5296):51-54

A general method for combining existing algorithms into new programs that are unequivocally preferable to any of the component algorithms is presented. This method, based on notions of risk in economics, offers a computational portfolio design procedure that can be used for a wide range of problems. Tested by solving a canonical NP-complete problem, the method can be used for problems ranging from the combinatorics of DNA sequencing to the completion of tasks in environments with resource contention, such as the World Wide Web.  相似文献   

Predicting the assembly of novel communities in urban ecosystems     

Andrade  Riley  Franklin  Janet  Larson  Kelli L.  Swan  Christopher M.  Lerman  Susannah B.  Bateman  Heather L.  Warren  Paige S.  York  Abigail 《Landscape Ecology》2021,36(1):1-15

Context

Ecological communities in urban ecosystems are assembled through ecological processes, such as species interactions, dispersal, and environmental filtering, but also through human factors that create and modify the landscape. These complex interactions make it difficult to untangle the relationships between social–ecological dynamics and urban biodiversity.

Objectives

As a result, there has been a call for research to address how human activities influence the processes by which ecological communities are structured in urban ecosystems. We address this research challenge using core concepts from landscape ecology to develop a framework that links social-ecological dynamics to ecological communities using the metacommunity perspective.

Methods

The metacommunity perspective is a useful framework to explore the assembly of novel communities because it distinguishes between the effects of local environmental heterogeneity and regional spatial processes in structuring ecological communities. Both are shaped by social–ecological dynamics in urban ecosystems.

Results

In this paper, we define social, environmental, and spatial processes that structure metacommunities, and ultimately biodiversity, in cities. We then address how our framework could be applied in urban ecosystem research to understand multi-scalar biodiversity patterns.

Conclusions

Our framework provides a theoretical and empirical foundation for transdisciplinary research to examine how social-ecological dynamics mediate the assembly of novel communities in urban ecosystems.

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Attempted in vitro maturation and fertilization of postmortem Sumatran rhinoceros (Dicerorhinus sumatrensis) oocytes     

Stoops MA  Bateman HL  Campbell MK  Roth TL 《Journal of zoo and wildlife medicine》2011,42(4):723-726

A study was conducted opportunistically to evaluate the potential of rescuing immature oocytes from the ovaries of the Sumatran rhinoceros postmortem. Recovered oocytes (n = 30) were placed in maturation culture for 36 hr and inseminated with frozen-thawed homologous spermatozoa. After culture, evaluation of nuclear maturation status revealed that a large number of oocytes were degenerated (n = 21), but nine oocytes were assessed at the germinal vesicle (n = 3), metaphase I (n = 3), and metaphase II (n = 3) stages. Frozen-thawed Sumatran rhinoceros spermatozoa were capable of binding to the zona pellucida of in vitro matured oocytes, but no fertilization or cleavage resulted. In conclusion, relatively large numbers of oocytes can be obtained by ovarian follicular aspiration postmortem in the Sumatran rhinoceros, and some of these oocytes are capable of achieving nuclear maturation in vitro. However, additional studies are required to improve maturation success and achieve fertilization in culture.  相似文献   

A national serological survey to verify Australia's freedom from porcine reproductive and respiratory syndrome   总被引：4，自引：0，他引：4  

MG GARNER  LJ GLEESON  PK HOLYOAKE  RM CANNON  WJ DOUGHTY 《Australian veterinary journal》1997,75(8):596-600

Objective To provide serological data to support Australia's claim of freedom from porcine reproductive and respiratory syndrome.
Design A national serological survey was designed to provide 99% confidence of detecting at least one infected pig herd in Australia, assuming that at least 5% of herds would have been exposed to porcine reproductive and respiratory syndrome virus and that at least 25% of the 'finisher' pigs in these herds would have antibodies to the virus.
Procedure A two-stage testing regime was used. All samples were tested with a commercially available enzyme-linked immunosorbent assay. If assay reactions were found, all samples from the herd were to be tested using the indirect immunofluorescence antibody assay.
Results Of the 875 samples from 163 herds from all States in Australia, there was some evidence of reactivity in only four samples from four herds on the enzyme-linked immunosorbent assay. Further testing using the indirect immunofluorescence antibody assay according to the study protocol demonstrated that the reactions were not due to the presence of specific porcine reproductive and respiratory syndrome virus antibodies in the sera.
Conclusion The results of this study support the view that Australian pigs are free of porcine reproductive and respiratory syndrome virus.  相似文献   

Canine Clinical Parasitology     

RM Barlow 《Australian veterinary journal》1994,71(6):190-190

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