134 research outputs found
Tsunami-Related Data: A Review of Available Repositories Used in Scientific Literature
Various organizations and institutions store large volumes of tsunami-related data, whose
availability and quality should benefit society, as it improves decision making before the tsunami
occurrence, during the tsunami impact, and when coping with the aftermath. However, the existing
digital ecosystem surrounding tsunami research prevents us from extracting the maximum benefit
from our research investments. The main objective of this study is to explore the field of data
repositories providing secondary data associated with tsunami research and analyze the current
situation. We analyze the mutual interconnections of references in scientific studies published in the
Web of Science database, governmental bodies, commercial organizations, and research agencies. A
set of criteria was used to evaluate content and searchability. We identified 60 data repositories with
records used in tsunami research. The heterogeneity of data formats, deactivated or nonfunctional
web pages, the generality of data repositories, or poor dataset arrangement represent the most
significant weak points. We outline the potential contribution of ontology engineering as an example
of computer science methods that enable improvements in tsunami-related data management
Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion
BACKGROUND: Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. METHODS: We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. RESULTS: The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. CONCLUSIONS: The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue
Energetic signatures of single base bulges: thermodynamic consequences and biological implications
DNA bulges are biologically consequential defects that can arise from template-primer misalignments during replication and pose challenges to the cellular DNA repair machinery. Calorimetric and spectroscopic characterizations of defect-containing duplexes reveal systematic patterns of sequence-context dependent bulge-induced destabilizations. These distinguishing energetic signatures are manifest in three coupled characteristics, namely: the magnitude of the bulge-induced duplex destabilization (ΔΔGBulge); the thermodynamic origins of ΔΔGBulge (i.e. enthalpic versus entropic); and, the cooperativity of the duplex melting transition (i.e. two-state versus non-two state). We find moderately destabilized duplexes undergo two-state dissociation and exhibit ΔΔGBulge values consistent with localized, nearest neighbor perturbations arising from unfavorable entropic contributions. Conversely, strongly destabilized duplexes melt in a non-two-state manner and exhibit ΔΔGBulge values consistent with perturbations exceeding nearest-neighbor expectations that are enthalpic in origin. Significantly, our data reveal an intriguing correlation in which the energetic impact of a single bulge base centered in one strand portends the impact of the corresponding complementary bulge base embedded in the opposite strand. We discuss potential correlations between these bulge-specific differential energetic profiles and their overall biological implications in terms of DNA recognition, repair and replication
Brain Complexity: Analysis, Models and Limits of Understanding
Abstract. Manifold initiatives try to utilize the operational principles of organisms and brains to develop alternative, biologically inspired computing paradigms. This paper reviews key features of the standard method applied to complexity in the cognitive and brain sciences, i.e. decompositional analysis. Projects investigating the nature of computations by cortical columns are discussed which exemplify the application of this standard method. New findings are mentioned indicating that the concept of the basic uniformity of the cortex is untenable. The claim is discussed that non-decomposability is not an intrinsic property of complex, integrated systems but is only in our eyes, due to insufficient mathematical techniques. Using Rosen’s modeling relation, the scientific analysis method itself is made a subject of discussion. It is concluded that the fundamental assumption of cognitive science, i.e., cognitive and other complex systems are decomposable, must be abandoned.
Complexity Theory for a New Managerial Paradigm: A Research Framework
In this work, we supply a theoretical framework of how organizations
can embed complexity management and sustainable development into their policies
and actions. The proposed framework may lead to a new management paradigm,
attempting to link the main concepts of complexity theory, change management,
knowledge management, sustainable development, and cybernetics. We highlight
how the processes of organizational change have occurred as a result of the move to
adapt to the changes in the various global and international business environments
and how this transformation has led to the shift toward the present innovation
economy. We also point how organizational change needs to deal with sustainability,
so that the change may be consistent with present needs, without compromising
the future
Some immunological findings in adult periodontitis
There is little doubt that immunological mechanisms play an important role in chronic inflammatory periodontal disease. At the same time, it is recognized that patient susceptibility is ultimately responsible for the clinical manifestation of the disease. In this context, the present study was undertaken to examine a range of systemic immunological parameters in patients with adult periodontitis (AP), so as to test the hypothesis that a specific pattern would identify diseased — possibly ‘at risk’ — patients. These parameters included serum IgA, IgG, IgM, IgD, C, transferrin, the presence of circulating immune complexes, and the number of circulating T (E‐rosette forming) cells. One hundred and forty AP patients and 70 healthy controls were examined. Following a complex statistical analysis only the levels of IgG, IgM and IgD were significantly increased in adult periodontitis (p < 0.05) while an increase in circulatory immune complexes was significant only for separate statistical tests. Although statistically different, the levels seen in AP patients were still within the normal range hence the clinical significance of the findings is such that it is unlikely that these systemic immunological parameters per se do define an ‘at risk’ population. 1989 Australian Dental Associatio
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