1,720,990 research outputs found
Temporal information systems in medicine
No full textThe effective and efficient use of information systems in health care organizations and services are a vital element of the quality of life world wide. The modeling of time has attracted interest from a number of research communities, each addressing aspects from its specific sphere of interests. The database systems community is interested in how to store, maintain, and query time-oriented data. The Artificial Intelligence (AI) community is interested in formal theories of time, temporal logics, temporal constraints and temporal reasoning techniques. The Artificial Intelligence in Medicine (AIM) community is interested in the broader issues. Temporal Information Systems in Medicine introduces the engineering of information systems for medically-related problems and applications. The chapters are organized into four parts; fundamentals, temporal reasoning & maintenance in medicine, time in clinical task, and the display of time-oriented clinical information. The chapters are self-contained with pointers to other relevant chapters or sections in this book when necessary. Time is of central importance and is a key component of the engineering process for information systems. About this book Presents a cutting edge text on Temporal Information Systems in Medicine. Chapters are self contained with pointers to other relevant material or chapters in this book. Serves as an introduction to a reader interested in a general theoretical understanding of temporal representation and reasoning, especially as it relates to medicine, and as a source for those interested in specific clinical time-oriented tasks, such as diagnosis or abstraction of clinical records. This book is designed as a secondary text or reference book for upper -undergraduate level students and graduate level students concentrating on computer science, biomedicine and engineering. Industry professionals and researchers working in health care management, temporal information systems in medicine, medical informatics, database management and AI will also find this book a valuable asset
Artificial Intelligence in Medicine, 12th Conference on Artificial Intelligence in Medicine, AIME 2009, Verona, Italy, July 18-22, 2009. Proceedings AIME 2009
No full textData Mining in Medicine
No full textClinical databases collect large volumes of information. Relationships and patterns within these data could provide new medical knowledge. Data mining has as major objective the discovery of knowledge from large amounts of data, offers many possibilities for identifying different data features less visible or hidden to common analysis techniques. This chapter focuses on a selection of techniques and illustrates their applicability to medical diagnostic and prognostic problems
Optimal metal domain size for photocatalysis with hybrid semiconductor-metal nanorods
Get PDFSemiconductor-metal hybrid nanostructures offer a highly controllable platform for light-induced charge separation, with direct relevance for their implementation in photocatalysis. Advances in the synthesis allow for control over the size, shape and morphology, providing tunability of the optical and electronic properties. A critical determining factor of the photocatalytic cycle is the metal domain characteristics and in particular its size, a subject that lacks deep understanding. Here, using a well-defined model system of cadmium sulfide-gold nanorods, we address the effect of the gold tip size on the photocatalytic function, including the charge transfer dynamics and hydrogen production efficiency. A combination of transient absorption, hydrogen evolution kinetics and theoretical modelling reveal a non-monotonic behaviour with size of the gold tip, leading to an optimal metal domain size for the most efficient photocatalysis. We show that this results from the size-dependent interplay of the metal domain charging, the relative band-alignments, and the resulting kinetics
Charge Carrier Dynamics in Photocatalytic Hybrid Semiconductor–Metal Nanorods: Crossover from Auger Recombination to Charge Transfer
Get PDFHybrid
semiconductor–metal nanoparticles (HNPs) manifest
unique, synergistic electronic and optical properties as a result
of combining semiconductor and metal physics via a controlled interface.
These structures can exhibit spatial charge separation across the
semiconductor–metal junction upon light absorption, enabling
their use as photocatalysts. The combination of the photocatalytic
activity of the metal domain with the ability to generate and accommodate
multiple excitons in the semiconducting domain can lead to improved
photocatalytic performance because injecting multiple charge carriers
into the active catalytic sites can increase the quantum yield. Herein,
we show a significant metal domain size dependence of the charge carrier
dynamics as well as the photocatalytic hydrogen generation efficiencies
under nonlinear excitation conditions. An understanding of this size
dependence allows one to control the charge carrier dynamics following
the absorption of light. Using a model hybrid semiconductor–metal
CdS–Au nanorod system and combining transient absorption and
hydrogen evolution kinetics, we reveal faster and more efficient charge
separation and transfer under multiexciton excitation conditions for
large metal domains compared to small ones. Theoretical modeling uncovers
a competition between the kinetics of Auger recombination and charge
separation. A crossover in the dominant process from Auger recombination
to charge separation as the metal domain size increases allows for
effective multiexciton dissociation and harvesting in large metal
domain HNPs. This was also found to lead to relative improvement of
their photocatalytic activity under nonlinear excitation conditions
Effect of surface coating on the photocatalytic function of hybrid CdS-Au nanorods
Get PDFHybrid semiconductor–metal nanoparticles are interesting materials for use as photocatalysts due to their tunable properties and chemical processibility. Their function in the evolution of hydrogen in photocatalytic water splitting is the subject of intense current investigation. Here, the effects of the surface coatings on the photocatalytic function are studied, with Au-tipped CdS nanorods as a model hybrid nanoparticle system. Kinetic measurements of the hydrogen evolution rate following photocatalytic water reduction are performed on similar nanoparticles but with different surface coatings, including various types of thiolated alkyl ligands and different polymer coatings. The apparent hydrogen evolution quantum yields are found to strongly depend on the surface coating. The lowest yields are observed for thiolated alkyl ligands. Intermediate values are obtained with L-glutathione and poly(styrene-co-maleic anhydride) polymer coatings. The highest efficiency is obtained for polyethylenimine (PEI) polymer coating. These pronounced differences in the photocatalytic efficiencies are correlated with ultrafast transient absorption spectroscopy measurements, which show a faster bleach recovery for the PEI-coated hybrid nanoparticles, consistent with faster and more efficient charge separation. These differences are primarily attributed to the effects of surface passivation by the different coatings affecting the surface trapping of charge carriers that compete with effective charge separation required for the photocatalysis. Further support of this assignment is provided from steady-state emission and time-resolved spectral measurements, performed on related strongly fluorescing CdSe/CdS nanorods. The control and understanding of the effect of the surface coating of the hybrid nanosystems on the photocatalytic processes is of importance for the potential application of hybrid nanoparticles as photocatalysts
Visualizing Ultrafast Electron Transfer Processes in Semiconductor–Metal Hybrid Nanoparticles: Toward Excitonic–Plasmonic Light Harvesting
Get PDFRecently, it was demonstrated that charge separation in hybrid metal–semiconductor nanoparticles (HNPs) can be obtained following photoexcitation of either the semiconductor or of the localized surface plasmon resonance (LSPR) of the metal. This suggests the intriguing possibility of photocatalytic systems benefiting from both plasmon and exciton excitation, the main challenge being to outcompete other ultrafast relaxation processes. Here we study CdSe-Au HNPs using ultrafast spectroscopy with high temporal resolution. We describe the complete pathways of electron transfer for both semiconductor and LSPR excitation. In the former, we distinguish hot and band gap electron transfer processes in the first few hundred fs. Excitation of the LSPR reveals an ultrafast (<30 fs) electron transfer to CdSe, followed by back-transfer from the semiconductor to the metal within 210 fs. This study establishes the requirements for utilization of the combined excitonic–plasmonic contribution in HNPs for diverse photocatalytic applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Novel Multilingual Report Generation System for Medical Applications
No full textThere has been an increasing demand for high quality medical data that are in a standard electronic format and easily shared. Although a great amount of effort has been invested to ease the process, an effective solution has yet to be found. In this study, we first discuss necessary features of an effective data collection and reporting system, and then reveal the conceptual view of a novel method that aims to encompass these features. We also present the design and implementation details of a Web-based prototype
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