1,746 research outputs found
A Multiscale Observational Case Study of the Development of an Isolated High Plains Tornadic Supercell
On 21 May 1995, a strong tornado developed with an isolated supercell in southwestern Nebraska. Largescale
conditions were not supportive of a tornadic thunderstorm outbreak; however, evidence suggests significant
mesoscale enhancements produced a local environment favorable for strong tornado formation. This case study
illustrates the importance of ââsituation awarenessââ and illustrates how mesoscale enhancements must be anticipated
by forecasters in order to properly assess rapidly changing atmospheric conditions
Evaluation of Transplanted Tissue-Engineered Oral Mucosa Equivalents in Severe Combined Immunodeficient Mice
The aim of this study was to determine the optimal stage of development at which transplant human ex vivo-produced oral mucosa equivalents (EVPOMEs) in vivo. EVPOMEs were generated in a serum-free culture system, without the use of an irradiated xenogeneic feeder layer, by seeding human oral keratinocytes onto a human cadaveric dermal equivalent, AlloDerm. EVPOMEs were cultured for 4 days submerged and then for 7 or 14 days at an air-liquid interface to initiate stratification before transplantation into SCID mice. AlloDerm, without epithelium, was used as a control. Mice were killed on days 3, 10, and 21 posttransplantation. Epithelium of the transplanted EVPOMEs was evaluated with the differentiation marker keratin 10/13. Dermal microvessel ingrowth was determined by immunohistochemistry with a mouse vascular marker, lectin binding from Triticum vulgaris. The presence and stratification of the epithelium were correlated with revascularization of the underlying dermis. The microvessel density of AlloDerm without epithelium was less than that of EVPOMEs with an epithelial layer. Microvessel density of the dermis varied directly with the degree of epithelial stratification of the EVPOMEs. The EVPOMEs cultured at an air-liquid interface for 7 days had the optimal balance of neoangiogenesis and epithelial differentiation necessary for in vivo grafting.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63269/1/107632703762687645.pd
The Point of Origin of the Radio Radiation from the Unresolved Cores of Radio-Loud Quasars
Locating the exact point of origin of the core radiation in active galactic
nuclei (AGN) would represent important progress in our understanding of
physical processes in the central engine of these objects. However, due to our
inability to resolve the region containing both the central compact object and
the jet base, this has so far been difficult. Here, using an analysis in which
the lack of resolution does not play a significant role, we demonstrate that it
may be impossible even in most radio loud sources for more than a small
percentage of the core radiation at radio wavelengths to come from the jet
base. We find for 3C279 that percent of the core flux at 15 GHz must
come from a separate, reasonably stable, region that is not part of the jet
base, and that then likely radiates at least quasi-isotropically and is
centered on the black hole. The long-term stability of this component also
suggests that it may originate in a region that extends over many Schwarzschild
radii.Comment: 7 pages with 3 figures, accepted for publication in Astrophysics and
Space Scienc
Higher-level goals in the processing of human action events
The concept of a goal critically separates dynamic events involving humans from other events. Human behaviours are motivated by goals, which are known to the actor but typically inferred on the part of the observer. Goals can be hierarchical in nature, such that a collection of sub-goals (e.g., getting a mug, boiling water) can be nested under a higher-level goal (e.g., making tea), which can be further nested under an even higher-level goal (e.g., making breakfast).
The diverse set of talks in this symposia all highlight the foundational role that goals play in action processing and representation. Eisenberg et al. detail how online prediction of othersâ goals shapes observersâ sampling of information during action observation. Howard and Woodward provide evidence that childrenâs memory for non-human events can be facilitated by priming children with their own goal-directed actions. Loucks and Meltzoff highlight the importance of goal structure in childrenâs memory for complex action sequences. Finally, Cooper presents a computational model to explain the emergence of goal-directed action hierarchies
Compounded perturbations in coastal areas: contrasting responses to nutrient enrichment and the regime of storm-related disturbance depend on life-history traits
1. Natural systems are exposed to compounded perturbations, whose changes in temporal
variance can be as important as those in mean intensity for shaping the structure of assemblages.
Specifically, climate-related physical disturbances and nutrient inputs due to natural
and/or anthropogenic activities occur concomitantly, but experimental tests of the simultaneous
effects of changes in the regime of more than one perturbation are generally lacking.
Filling this gap is the key to understand ecological responses of natural assemblages to
climate-related change in the intensity and temporal patterning of physical disturbance combined
with other global stressors.
2. Responses to factorial manipulations of nutrient enrichment, mean intensity and temporal
variability in storm-like mechanical disturbance were examined, using benthic assemblages of
tide-pools as model system.
3. Response variables were mean abundance values and temporal variances of taxa with different
life-traits. Consistent negative effects of disturbance intensity were observed for the mean
cover of long-living taxa (algal canopies and the polychaete Sabellaria alveolata), whose temporal
fluctuations were also reduced by more severe mechanical stress. More resilient taxa
(ephemeral algae, mostly green of the genus Ulva) increased under enriched conditions, particularly
when low-intensity events were irregularly applied over time. Opposite effects of disturbance
intensity depending on nutrient availability occurred on filamentous algae (e.g. red of
the genus Ceramium). This was probably due to the fact that, although nutrient enrichment
stimulated the abundance of both algal groups, when this condition was combined with relatively
mild physical disturbance the competitively superior ephemeral green algae tended to
become dominant over filamentous red algae. The same did not occur under high intensity of
disturbance since it likely damaged large, foliose fronds of Ulva-like forms more than small, filamentous
fronds of Ceramium-like forms. Grazers were positively affected by nutrients, likely
responding indirectly to more food available.
4. A direct relationship between the mean abundance of most organisms and their temporal
fluctuations was documented. However, all organisms persisted throughout the study, even
under experimental conditions associated to the largest temporal variation in their abundance,
likely due to their ability to resist to/quickly recover from, the applied perturbations. Therefore,
in systems with great recovery abilities of dominant organisms (e.g. rocky intertidal,
grasslands), effects of traits of the regime of disturbance and nutrient enrichment may modulate the fluctuations of populations not through the elimination and substitution of species,
but through changes in relative abundances of the same species. This contrasts with the
theory that temporal variation in abundance would be directly related to the risk of local
extinction. Present findings enable more accurate predictions of the consequences of climatic
and non-climatic scenarios on the biodiversity of marine and terrestrial systems sharing analogous
functional traits of organisms. Future more intense physical disturbances are expected to
exert negative effects on slow-growing/recovering species (e.g. habitat-formers) irrespectively of
the temporal patterning of the same disturbances and nutrient inputs. On the contrary, more
resistant species (e.g. encrusting algae on rocky shores or below-ground vegetation in grasslands)
are expected to benefit from intense physical disturbance. Species whose abundance is
more directly related to the availability of nutrients (e.g. filamentous and ephemeral algae or
herbs) are expected to generally increase under enriched conditions, but their ability to eventually
become dominant would depend on their ability to grow fast and attain cover large
enough to overwhelm any possible control of concomitant disturbance intensity on their abundance.
If, such as in the present examined system, virtually all organisms can persist, over the
temporal scale of the experiment, under any combination of physical disturbance and nutrient
availability, the resulting overall diversity is not predicted to change drastically. Nevertheless,
low-intensity events evenly distributed and high-intensity events irregularly distributed appear
as the conditions supporting the highest richness of taxa, independently of the availability of
nutrients
Lack of cardiac differentiation in c-kit-enriched porcine bone marrow and spleen hematopoietic cell cultures using 5-azacytidine
The adult spleen is a source of early hematopoietic stem cells (HSC). We therefore studied whether culturing spleen or bone marrow (BM) HSC in medium containing 5-azacytidine could induce a cardiac phenotype. c-kit enrichment and depletion of adult pig spleen and BM mononuclear cells were obtained by magnetic bead separation using biotinylated pig stem cell factor (c-kit ligand). Cells were incubated with 5-azacytidine for 24 h and refreshed with 5-azacytidine-free medium every 48 h. Western blot was used to detect cardiac troponin and myosin heavy chains. Alth
Trabecular bone score (TBS) as a new complementary approach for osteoporosis evaluation in clinical practice.
Trabecular bone score (TBS) is a recently-developed analytical tool that performs novel grey-level texture measurements on lumbar spine dual X-ray absorptiometry (DXA) images, and thereby captures information relating to trabecular microarchitecture. In order for TBS to usefully add to bone mineral density (BMD) and clinical risk factors in osteoporosis risk stratification, it must be independently associated with fracture risk, readily obtainable, and ideally, present a risk which is amenable to osteoporosis treatment. This paper summarizes a review of the scientific literature performed by a Working Group of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis. Low TBS is consistently associated with an increase in both prevalent and incident fractures that is partly independent of both clinical risk factors and areal BMD (aBMD) at the lumbar spine and proximal femur. More recently, TBS has been shown to have predictive value for fracture independent of fracture probabilities using the FRAXÂź algorithm. Although TBS changes with osteoporosis treatment, the magnitude is less than that of aBMD of the spine, and it is not clear how change in TBS relates to fracture risk reduction. TBS may also have a role in the assessment of fracture risk in some causes of secondary osteoporosis (e.g., diabetes, hyperparathyroidism and glucocorticoid-induced osteoporosis). In conclusion, there is a role for TBS in fracture risk assessment in combination with both aBMD and FRAX
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Radiation densitometry in tree-ring analysis: a review and procedure manual
An x-ray densitometry of wood facility is being established by the Environmental Sciences Division, Oak Ridge Natioanl Laboratory (ORNL). The objective is to apply tree-ring data to determine whether or not there is a fertilizer effect on tree growth from increased atmospheric carbon dioxide since the beginning of the industrial era. Intra-ring width and density data, including ring-mass will be detemined from tree-ring samples collected from sites located throughout the United States and Canada. This report is designed as a guide to assist ORNL scientists in building the x-ray densitometry system. The history and development of x-ray densitometry in tree-ring research is examined and x-ray densitometry is compared with other techniques. Relative wood and tree characteristics are described as are environmental and genetic factors affecting tree growth responses. Methods in x-ray densitometry are examined in detail and the techniques used at four operating laboratories are described. Some ways that dendrochronology has been applied in dating, in wood quality, and environmental studies are presented, and a number of tree-ring studies in Canada are described. An annotated bibliography of radiation densitometry in tree-ring analysis and related subjects is included
Developing a survey to collect expertise in agile product line requirements engineering processes
Current agile methods are focused on practices of small, rapid developing and iteration, more people oriented, less documentation projects, and the use of the methods in large, product line projects are somehow difficult. UTD and GESSI have started a project to develop an expert system that can assist a requirements enginer in selecting a requirements engineering process that is well suited for their project, in particular with respect to the use of agile and product line engineering methods. To the best of our knowledge, this is the first expert system to do this. In this report, we present the questionnaire and the rationale behind it. This report is complemented with LSI-07-14-R.Postprint (published version
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