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At least 217 records · Page 12Linked to original sources

PubMed1999

Fast digital simulation of spiking neural networks and neuromorphic integration with SPIKELAB.

We present a simulation environment called SPIKELAB which incorporates a simulator that is able to simulate large networks of spiking neurons using a distributed event driven simulation. Contrary to a time driven simulation, which is usually used to simulate spiking neural networks, our simulation needs less computational resources because of the low average activity of typical networks. The paper addresses the speed up using an event driven versus a time driven simulation and how large networks can be simulated by a distribution of the simulation using already available computing resources. It also presents a solution for the integration of digital or analogue neuromorphic circuits into the simulation process.

Action Potentials↗

PubMedDate not supplied

A picture archiving and communication system module for radiology.

This paper presents the design and implementation of a clinical picture archiving and communication system (PACS) module within the radiology department of a 700-bed teaching hospital. The system is composed of an integrated network of digital devices used to electronically acquire, store, manage, and display radiological text and image information. Operationally the system behaves as a large queueing network allowing processes to operate concurrently in a coordinated and prioritized fashion. Secondary reviews (radiology conferences and fast case reviews by clinicians) are being conducted from a 512 X 512 CRT viewing station. Preliminary evaluation based on formal survey and usage statistics shows that the system is rapidly being accepted by radiologists and clinicians for the review and processing of digital radiographic images.

Hospital Bed Capacity, 500 and over↗

PubMed1995

A World-Wide Web radiology teaching file server on the Internet.

OBJECTIVE: Radiology departments have traditionally used film-based collections of interesting cases for teaching purposes. Film-based files are expensive to create and duplicate, and they physically occupy considerable space. As one solution to these problems, our department created an on-line radiology teaching file in digital format. MATERIALS AND METHODS: Our teaching file resides on a Macintosh Quadra 700 computer that is connected to the Internet, a worldwide network of interconnected computers, via our campus Ethernet network. Our digital teaching file images and text are composed in HyperText Markup Language (HTML) and are made available to the world with Webserver software known as MacHTTP. These teaching files are accessed using World-Wide Web (WWW) client software such as Mosaic, MacWeb, or Netscape. RESULTS: Our digital teaching file is available at no charge to anyone in the world with access to the Internet and WWW client software. Our radiology residents can access this file via several workstations in our department. Mosaic is an easy-to-use interface, and the use of our digital teaching file has increased significantly. In the 3 months since its creation, our teaching file has been accessed not only by our radiology residents but also by hundreds of other users in 33 countries. CONCLUSION: Use of Mosaic and the WWW format has resulted in an easy-to-use hypertext interface to the Internet, which allows even persons with little computer experience to navigate through the Internet, read text files, view images (stills and movies), and download files by merely pointing with the mouse and clicking on items of interest. This has allowed us to maintain a central teaching file that is physically small and easy to share with all the hospitals in our system. We invite the worldwide radiology community to access these files and to submit cases from their own teaching files to share with the rest of the world.

Computer Communication Networks↗

PubMed2000

A digital image analysis and neural network based system for identification of third-stage parasitic strongyle larvae from domestic animals.

A competitive learning vector quantization artificial neural network (ANN) was trained to identify third-stage parasitic strongyle larvae from domestic animals on the basis of quantitative data obtained from processed digital images of larvae. For this reason, various quantitative features obtained from processed digital images of larvae were tested as to whether they are variant or invariant to the shape taken by the motile larvae during image recording. A total of 255 images of 57 individual larvae in various shapes belonging to five genera were recorded. Following image processing, 16 features were measured, of which seven were selected as invariant to larva shape. By trial and error, two of those features, 'area' and 'perimeter', along with the quantitative features used in conventional identification, 'overall body length', 'width' and 'extension of sheath' (tip of larva to tip of sheath), were used as an effective training data set for the ANN. This ANN coupled with an image analysis facility and a knowledge relational database became the basis for developing a computer-based larva identification system whose overall identification performance was 91.9%. The advantages of this system are its speed and objectivity. The objectivity of the system is based on the fact that it is not subject to inter- and intra-observer variability arising from the user's profile of competency in interpreting subjective and non-quantifiable descriptions. The limitations of the system are that it cannot handle raw images but only data extracted from images, its performance depends on the reliability of the input vectors used as training data for the ANN, and its use is restricted only to well-equipped laboratories due to its requirement for expensive instrumentation.

Animals↗

PubMed2006

Prediction of near-surface soil moisture at large scale by digital terrain modeling and neural networks.

The capability of Artificial Neural Network models to forecast near-surface soil moisture at fine spatial scale resolution has been tested for a 99.5 ha watershed located in SW Spain using several easy to achieve digital models of topographic and land cover variables as inputs and a series of soil moisture measurements as training data set. The study methods were designed in order to determining the potentials of the neural network model as a tool to gain insight into soil moisture distribution factors and also in order to optimize the data sampling scheme finding the optimum size of the training data set. Results suggest the efficiency of the methods in forecasting soil moisture, as a tool to assess the optimum number of field samples, and the importance of the variables selected in explaining the final map obtained.

Humidity↗

PubMedDate not supplied

The origins of informatics.

This article summarizes the origins of informatics, which is based on the science, engineering, and technology of computer hardware, software, and communications. In just four decades, from the 1950s to the 1990s, computer technology has progressed from slow, first-generation vacuum tubes, through the invention of the transistor and its incorporation into microprocessor chips, and ultimately, to fast, fourth-generation very-large-scale-integrated silicon chips. Programming has undergone a parallel transformation, from cumbersome, first-generation, machine languages to efficient, fourth-generation application-oriented languages. Communication has evolved from simple copper wires to complex fiberoptic cables in computer-linked networks. The digital computer has profound implications for the development and practice of clinical medicine.

Computer Communication Networks↗

PubMed1994

[Cost effectiveness and patient benefit of digital image management systems for radiology].

In many countries today, politicians are faced with the difficulty of having to reduce the overproportional increase in the cost of healthcare. In this context the contribution of medical technology to costs in the total spent are nearly always overestimated and its potential for savings underestimated. Based on international studies, investment and subsequent running costs for large, high-tech systems for diagnosis and therapy will be shown to account for only about 1% of the total cost of healthcare. Impressive examples of the application of computed tomography, magnetic resonance tomography and digital angiography deliver statistics regarding valid patient benefits and efficiency of modern diagnostic imaging systems. Studies about related therapeutic possibilities of angioplasty and extra-corporal lithotripsy demonstrate the overall economic advantages of modern medical technology. Arising from the positive results due to the use of such equipment, the additional cost savings potential to be expected by networking these digital modalities with one another, as well as with other information and communications technology systems, will be analysed. The results will be assessed and compared to experience gained from routine clinical operation of such integrated systems. 72% of the total turnover of the Medical Engineering Group of Siemens AG for diagnostic imaging modalities in 1991/1992 arose from digital imaging modalities, and this percentage is expected to continue to increase. This paper will concentrate on these modern digital methods.

Computer Communication Networks↗

PubMed1991

State-of-the-art digital radiography.

Technologic advances in digital radiography have improved the ways in which radiographic images are acquired, displayed, transmitted, recorded, and archived. With computed radiography, performed with storage phosphor plates and interactive high-resolution workstations, radiation dose is reduced and repeat exposures necessitated due to technical errors are eliminated. Digital fluorography allows reductions in dose, procedure time, and film costs. These digital imaging modalities have been well accepted clinically and are equal in diagnostic accuracy to conventional methods. Teleradiology has advanced with the development of laser film digitization, fiberoptic networks, and dial-up circuit switching technology. Laser film printers yield improved hard copies of transmitted images, but further work is needed to faithfully reproduce the images displayed on high-resolution work-stations. Although the capacity for archiving digital image data has increased (260,000 examinations or 23,500 Gbytes can be stored in a six-unit optical disc library), higher capacity storage media are needed. Further technologic advances in the speed of image transmission and storage capacity are anticipated.

Humans↗

PubMed1976

International standard (C.C.I.T.T.) for transmitting biomedical analogue and digital data on the public telephone network.

Analogue transmission of biomedical signals over the public telephone network has advantages from the economic point of view over digitalized transmission. This paper deals with the special problems encountered with the transmission of biomedical signals. Furthermore, the new international transmission standard C.C.I.T.T. recommendation V. 16 is introduced. This standard has recently been adopted by the relevant study group and has been presented to the Plenary Assembly of the C.C.I.T.T. for final approval. This standard is compatible with the existing public telephone networks. The technical specifications of this standard allow the transmission of the three-channel ECG for diagnostic purposes, e.g., remote processing and computer-assisted evaluation, as well as the transmission of the one-channel ECG with acoustic coupling, e.g., in emergency cases and for pace maker monitoring.

Analog-Digital Conversion↗

PubMed2004

Digit and command interpretation for electronic book using neural network and genetic algorithm.

This paper presents the interpretation of digits and commands using a modified neural network and the genetic algorithm. The modified neural network exhibits a node-to-node relationship which enhances its learning and generalization abilities. A digit-and-command interpreter constructed by the modified neural networks is proposed to recognize handwritten digits and commands. A genetic algorithm is employed to train the parameters of the modified neural networks of the digit-and-command interpreter. The proposed digit-and-command interpreter is successfully realized in an electronic book. Simulation and experimental results will be presented to show the applicability and merits of the proposed approach.

Algorithms↗

PubMed1990

A cost analysis of film image management and four PACS based on different network protocols.

Picture Archive and Communication Systems (PACS), which allow the electronic acquisition, storage, transportation, and viewing of medical images, hold the eventual promise of reduced costs, improved image-management logistics, and ultimately, improved patient care. But at what point in the future will PACS really cost less than film-based image management for a given hospital size; and how are these costs affected by the choice of the digital communication network? To address these questions, a static differential cost model has been constructed. PAC systems based on two high-speed networks (less than 150 megabytes per second Mbps) and two low-speed networks, as well as film, were considered for five different sized hospitals (ranging from 15,000 to 125,000 procedures per year) and two time periods (1995 and 2000). PACS equipment was assumed to have a payoff of five years. The model considered all capital and supply costs and personnel costs for the PACS and for film storage and retrieval. It did not consider any possible cost savings from logistics improvement likely to result from the adoption of a PACS. Based on the assumptions outlined, high-speed-network PACS are less costly than those based on low-speed networks for all scenarios considered. Further, even though all possible PACS cost savings were not considered, high-speed network PACS appear to be less costly than film for hospitals larger than 60,000 procedures in 1995 and larger than 15,000 in 2000, while low-speed-network PACS should cost less than film for 60,000 and 30,000 procedure hospitals in 1995 and 2000 respectively.

Computer Communication Networks↗

PubMedDate not supplied

Interfacing the PACS and the HIS: results of a 5-year implementation.

An interface was created between the Department of Defense's hospital information system (HIS) and its two picture archiving and communication system (PACS)-based radiology information systems (RISs). The HIS is called the Composite Healthcare Computer System (CHCS), and the RISs are called the Medical Diagnostic Imaging System (MDIS) and the Digital Imaging Network (DIN)-PACS. Extensive mapping between dissimilar data protocols was required to translate data from the HIS into both RISs. The CHCS uses a Health Level 7 (HL7) protocol, whereas the MDIS uses the American College of Radiology-National Electrical Manufacturers Association 2.0 protocol and the DIN-PACS uses the Digital Imaging and Communications in Medicine (DICOM) 3.0 protocol. An interface engine was required to change some data formats, as well as to address some nonstandard HL7 data being output from the CHCS. In addition, there are differences in terminology between fields and segments in all three protocols. This interface is in use at 20 military facilities throughout the world. The interface reduces the amount of manual entry into more than one automated system to the smallest level possible. Data mapping during installation saved time, improved productivity, and increased user acceptance during PACS implementation. It also resulted in more standardized database entries in both the HIS (CHCS) and the RIS (PACS).

Computer Systems↗

PubMed1994

Picture archiving and communication systems (PACS) for medical application.

The term 'Picture Archiving and Communication Systems' (PACS) applies to networks of digital image modalities, image workstations and mass image stores connected among each other by image data communication structures and controlled by appropriate image and data management. Predominantly, PACS are intended for application in the medical imaging domain, particularly in hospitals, where, by completely replacing the currently used films, they are supposed to lead to the 'filmless radiology'. The development of PACS is still one of the challenging tasks in the computer engineering field, because the giant amounts of digital image data produced in medical diagnostics require the introduction of novel architectures and technologies. This article describes the key components of PACS. Typical user environments are analysed and the requirements on the performance of the elements of a PACS are defined. The bottlenecks of current technologies are evaluated and examples of advanced approaches to PACS networks, archive modules and image workstations are given.

Computer Communication Networks↗

PubMed2002

Multichannel digital transmission in an optical network of communicating molecules.

In present telecommunication networks, information transfer relies on the interplay of optical and electrical signals. Data are communicated optically but processed electronically. Methods to maintain the propagating signals solely at the optical level must be developed to overcome the transmission capacities and speed limits imposed by the electronic components. We have demonstrated that molecular switches can be used to gate optical signals in response to optical signals. We have realized a simple optical network consisting of three light sources, one cell containing a solution of three fluorescent molecules, one cell containing a solution of a three-state molecular switch and a detector. The light emitted by the three fluorophores is absorbed by the three states of the molecular switch. Using this simple operating principle, we have shown that multichannel digital transmission can be implemented on an ensemble of communicating molecules relying exclusively on the interplay of optical inputs and optical outputs.

Journal Article↗

PubMed1996

Digital imaging in anatomic pathology.

Advances in computer technology continue to bring new innovations to departments of anatomic pathology. This article briefly reviews the present status of digital optical imaging, and explores the directions that this technology may lead over the next several years. Technical requirements for digital microscopic and gross imaging, and the available options for image archival and retrieval are summarized. The advantages of digital images over conventional photography in the conference room, and the usefulness of digital imaging in the frozen section suite and gross room, as an adjunct to surgical signout and as a resource for training and education, are discussed. An approach to the future construction of digital histologic sections and the computer as microscope is described. The digital technologic applications that are now available as components of the surgical pathologist's workstation are enumerated. These include laboratory information systems, computerized voice recognition, and on-line or CD-based literature searching, texts and atlases and, in some departments, on-line image databases. The authors suggest that, in addition to these resources that are already available, tomorrow's surgical pathology workstation will include network-linked digital histologic databases, on-line software for image analysis and 3-D image enhancement, expert systems, and ultimately, advanced pattern recognition capabilities. In conclusion, the authors submit that digital optical imaging is likely to have a significant and positive impact on the future development of anatomic pathology.

Humans↗

PubMed2001

Cost analysis of Turku University Central Hospital PACS in 1998.

Introduction of a picture archiving and communication system (PACS) into an old hospital poses several problems since the system cannot be implemented instantaneously. We analysed the costs of a halfway implemented PACS in Turku University Central Hospital (TUCH) during 1998. Manual and digital archiving in 1998 continued parallel so that only 10% reduction of film usage was achieved. A 21% increase in image manipulation and storage expenses occurred. A calculation based on potential 90% reduction of film usage and changes in the amount of personnel suggest some direct savings. Also, indirect savings due to more efficient patient treatment and the reduction of time spent in the hospital, and overhead costs of information handling are expected to lead to savings. However, these savings were not included in our calculations. When full-scale PACS is installed, equipment investments, network and digital ware maintenance costs will drop from 121 to 116% compared with traditional film archiving activity costs.

Academic Medical Centers↗

PubMed2006

Abnormalities of retinal microvascular structure and risk of mortality from ischemic heart disease and stroke.

Abnormalities of the retinal microcirculation are found in hypertension and diabetes and predict cardiovascular mortality. This study examined the relationship between abnormalities of the retinal microvasculature and death from ischemic heart disease (IHD) and stroke. A population-based, nested case-control study was undertaken within the Beaver Dam Eye Study. Subjects (43 to 74 years) who died of IHD (n=126) or stroke (n=28) over a 10-year period were age and gender matched with controls subjects (n=528; case:control matching, approximately 1:4). Retinal photographs of cases and controls were digitized and analyzed using a computer-based technique. Increased risk of IHD death was associated with a suboptimal relationship of arteriolar diameters at bifurcation (P=0.02 unadjusted) and decreased retinal arteriolar tortuosity (P=0.011 unadjusted). These associations remained significant after adjustment for age, sex, past history of cardiovascular disease, and other known cardiovascular risk factors. Increased arteriolar length:diameter ratio, a measure of generalized arteriolar narrowing, was associated with increased stroke mortality (P=0.02 unadjusted). This association was independent of age and gender but was attenuated by adjustment for systolic blood pressure (P=0.15). Other quantitative measures of the retinal microvascular network (eg, venular tortuosity and arteriolar and venular bifurcation angle) were not associated with death from IHD or stroke. Retinal microvascular abnormalities are predictive of death from IHD and stroke. A detailed assessment of the retinal microvascular network from digitized photographs may be useful in the noninvasive assessment of target organ damage and cardiovascular risk.

Aged↗

PubMed2000

Common object request broker architecture (CORBA)-based security services for the virtual radiology environment.

The US Army Great Plains Regional Medical Command (GPRMC) has a requirement to conform to Department of Defense (DoD) and Army security policies for the Virtual Radiology Environment (VRE) Project. Within the DoD, security policy is defined as the set of laws, rules, and practices that regulate how an organization manages, protects, and distributes sensitive information. Security policy in the DoD is described by the Trusted Computer System Evaluation Criteria (TCSEC), Army Regulation (AR) 380-19, Defense Information Infrastructure Common Operating Environment (DII COE), Military Health Services System Automated Information Systems Security Policy Manual, and National Computer Security Center-TG-005, "Trusted Network Interpretation." These documents were used to develop a security policy that defines information protection requirements that are made with respect to those laws, rules, and practices that are required to protect the information stored and processed in the VRE Project. The goal of the security policy is to provide for a C2-level of information protection while also satisfying the functional needs of the GPRMC's user community. This report summarizes the security policy for the VRE and defines the CORBA security services that satisfy the policy. In the VRE, the information to be protected is embedded into three major information components: (1) Patient information consists of Digital Imaging and Communications in Medicine (DICOM)-formatted fields. The patient information resides in the digital imaging network picture archiving and communication system (DIN-PACS) networks in the database archive systems and includes (a) patient demographics; (b) patient images from x-ray, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US); and (c) prior patient images and related patient history. (2) Meta-Manager information to be protected consists of several data objects. This information is distributed to the Meta-Manager nodes and includes (a) radiologist schedules; (b) modality worklists; (c) routed case information; (d) DIN-PACS and Composite Health Care system (CHCS) messages, and Meta-Manager administrative and security information; and (e) patient case information. (3) Access control and communications security is required in the VRE to control who uses the VRE and Meta-Manager facilities and to secure the messages between VRE components. The CORBA Security Service Specification version 1.5 is designed to allow up to TCSEC's B2-level security for distributed objects. The CORBA Security Service Specification defines the functionality of several security features: identification and authentication, authorization and access control, security auditing, communication security, nonrepudiation, and security administration. This report describes the enhanced security features for the VRE and their implementation using commercial CORBA Security Service software products.

Artificial Intelligence↗