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At least 109 records · Page 6Linked to original sources
PubMed2003

Catchment areas of panoramic snapshots in outdoor scenes.

We took panoramic snapshots in outdoor scenes at regular intervals in two- or three-dimensional grids covering 1 m2 or 1 m3 and determined how the root mean square pixel differences between each of the images and a reference image acquired at one of the locations in the grid develop over distance from the reference position. We then asked whether the reference position can be pinpointed from a random starting position by moving the panoramic imaging device in such a way that the image differences relative to the reference image are minimized. We find that on time scales of minutes to hours, outdoor locations are accurately defined by a clear, sharp minimum in a smooth three-dimensional (3D) volume of image differences (the 3D difference function). 3D difference functions depend on the spatial-frequency content of natural scenes and on the spatial layout of objects therein. They become steeper in the vicinity of dominant objects. Their shape and smoothness, however, are affected by changes in illumination and shadows. The difference functions generated by rotation are similar in shape to those generated by translation, but their plateau values are higher. Rotational difference functions change little with distance from the reference location. Simple gradient descent methods are surprisingly successful in recovering a goal location, even if faced with transient changes in illumination. Our results show that view-based homing with panoramic images is in principle feasible in natural environments and does not require the identification of individual landmarks. We discuss the relevance of our findings to the study of robot and insect homing.

Animals↗
PubMed1996

The RWJF Community Snapshots Study: introduction and overview.

Teams of researchers visited fifteen communities--selected to reflect a range of health care market development, regions, and population size--to obtain a "snapshot" of health system change. The study found that organizational change is pervasive, even in those communities that do not receive attention in the trade press, but that much of the change has not yet affected consumers. While the forces driving change are similar across the communities, the responses--and the shape of change--differ in important ways. Factors leading to the differences include the size and capabilities of existing health care organizations, the community's experience with managed care, and the political and business cultures of the community.

Catchment Area, Health↗
PubMed2004

Apolipoprotein E genotyping: accurate, simple, high throughput method using ABI Prism SNaPshot Multiplex System.

Apolipoprotein E (apo E) is an essential constituent of several plasma lipoproteins, and plays an important role in lipoprotein metabolism. The apo E gene exhibits two common functional polymorphisms, producing 3 isoforms known to be associated with the risks of developing cardiovascular disease and susceptibility to Alzheimer's disease. Numerous different methods have been established for determining the three apo E isoforms, yet there are disadvantages and ambiguities associated with all of them. We used a method adapted for multiplex automated primer extension analysis by improving a commercially available protocol (SNaPshot) and simultaneously typing apo E single nucleotide polymorphisms (SNPs) encoding for isoforms at codon 112 and 158. This protocol relies on the extension with fluorescent dideoxyNTPs of a primer that ends one nucleotide 5' of a given SNP (minisequencing). Improvement of the method is achieved by incorporating into the minisequencing reaction two pooled primers corresponding to both apo E SNPs followed by analysis on an ABI PRISM 310 DNA sequencer. We found full concordance with genotypes determined using universal heteroduplex. This method is readily available for many laboratories and is a simple, unequivocal easy to use technique suitable for large amount of clinical samples that may provide a significant improvement over previously reported methods for apo E genotyping.

Alzheimer Disease↗
PubMed2000

Benchmarking method relies on data snapshots.

This surgical performance measurement methodology takes a data 'snapshots' of peer facilities. Data are collected within the same time window. Reports compare participants with similar surgical facilities. Top performers' methods are shared with all participants in the interest of sharing proven quality techniques.

Benchmarking↗
PubMed2003

Global health report. A snapshot of the payer systems, major diseases and workforce trends from around the world.

International trade and travel have rendered political and geographic boundaries irrelevant when it comes to diseases. HIV and SARS are among the more recent examples of deadly viruses that spread swiftly from one continent to the next before international health experts can identify them, much less begin to search for a cure. This snapshot of global health issues looks at payer systems from a cross section of nations, lists the world's eight most infectious diseases and their rate of incidence by region, and pays special attention to the shortage of health care workers, which has reached crisis proportions in many areas and is pitting nation against nation in the competition for qualified staff.

Communicable Diseases↗
PubMed2005

IQLM and CLMA take a snapshot of America's hospital laboratory quality management.

CLMA volunteered to conduct an online pilot survey of its membership to help the Institute for Quality in Laboratory Medicine (IQLM) determine quality management activities in laboratories. Among the hospital-based members who were surveyed, approximately 25 percent responded. The data they volunteered provide a snapshot of the current state of laboratory quality management. The pilot survey is part of a larger IQLM plan to develop networks of laboratories to monitor and evaluate laboratory practices and services to enhance laboratory medicine. This pilot survey will be used by IQLM as a model to establish quality and patient safety networks, applicable to laboratories of all sizes and types. Performance comparisons and best practices may then be shared to reduce laboratory errors and improve patient safety.

Data Collection↗
PubMed1991

Morphometry of the neonatal fetal alcohol syndrome face from 'snapshots'.

Recognition of alcohol-related birth defects is less successful in the neonate than in older children. Clarren et al. (1987) were able to describe the geometry of the FAS face at age 7. To define neonatal facial features of FAS, 3 reference points were used to map 7 frontal and 7 profile landmarks coded as standardized cartesian coordinates. These landmarks were digitized from snapshots of 21 neonates, prospectively diagnosed as FAS blinded for prenatal alcohol exposure, and 76 non-FAS controls. In the controls, race was found to be a significant determinant of landmarks, as expected. Using discriminant analysis and controlling for race, the FAS face was characterized by landmark measurements which correspond to short palpebral fissure, scooping out of the nasal bridge and thin vermilion [F(4,71)-7.8, r sq-30%, p < .01]. Jackknifed sensitivity was 75%, specificity, 79%. These findings suggest that FAS-defining features can be quantified in the neonate via computer-based screening of infants from at-risk pregnancies.

Alcoholism↗
PubMedDate not supplied

Dynamic contrast enhancement of intracranial tumors with snapshot-FLASH MR imaging.

PURPOSE: To investigate whether exact evaluation of the dynamic contrast enhancement pattern within intracranial tumors can help to classify tumor histology and vascularity. METHOD: Forty-nine patients suffering from different intra- and extraaxial intracranial tumors underwent MR-examination in a 1.5-T superconductive whole body system. After rapid injection of Gd-DTPA, 48 images were acquired during the first 1.5 to 2 minutes of contrast enhancement within the tumors. A fast snapshot-FLASH imaging technique allowed measurement times of 1 second per image. Appearance of Gd-DTPA in a venous sinus served as a temporal reference point. Transformation of 48 discrete measurement points (mean signal values of the enhancing tumor region) into a continuous curve, using a cubic spline approximation, allowed calculation of the time of maximum signal increase (Tm1) and the following time of half maximum increase (Tm2). These time parameters were compared to histopathologic findings, especially the degree of tumor vascularization. RESULTS: Significantly different dynamic patterns of the early enhancement period were found for the different tumors. All eight neurinomas, typically less vascularized than most meningiomas, showed a characteristically prolonged contrast enhancement with a long Tm2. Histopathologic findings concerning the degree of vascularization showed two subtypes in meningiomas (n = 17) as well as in pituitary macroadenomas (n = 7). This was confirmed by dynamic evaluation in all cases, in the sense that short Tm1 and Tm2 were found in cases with higher degrees of vascularization. Negatives values of Tm1 were measured in two glomus jugulare tumors, reflecting the arterialization of these vascular tumors. In neuroepithelial tumors (n = 15), the glioblastomas (n = 7) showed very short Tm1 compared to the lower grade gliomas (n = 8). This is explained by histologic findings of pathologic vessels with arteriovenous shunts. CONCLUSION: The evaluated dynamic time parameters can be used to narrow differential diagnostic possibilities and to infer the degree of vascularization of intracranial tumors.

Adenoma↗
PubMed1993

Snapshots versus medical photographs: understanding the difference is your key to better dermatologic office photography.

A medical photograph in contradistinction to a snapshot accurately reproduces and maximizes clinically significant information while minimizing extraneous or irrelevant factors. Obtaining a top-notch medical photograph requires not only proper equipment but also rapid, sophisticated analysis of the clinical situation. Only then can major features including lesional size and distribution and more subtle details such as borders, color, and topography be selectively highlighted. First-rate medical photographs not only enhance the accuracy of diagnosis but also facilitate subsequent assessment of therapeutic efficacy. Furthermore, instruction of students and residents and continuing medical education of practicing clinicians depend on our photographic acumen.

Dermatology↗
PubMed2004

Taking snapshots of photoexcited molecules in disordered media by using pulsed synchrotron X-rays.

Photoexcited molecules are quintessential reactants in photochemistry. Structures of these photoexcited molecules in disordered media in which a majority of photochemical reactions take place remained elusive for decades owing to a lack of suitable X-ray sources, despite their importance in understanding fundamental aspects in photochemistry. As new pulsed X-ray sources become available, short-lived excited-state molecular structures in disordered media can now be captured by using laser-pulse pump, X-ray pulse-probe techniques of third-generation synchrotron sources with time resolutions of 30-100 ps, as demonstrated by examples in this review. These studies provide unprecedented information on structural origins of molecular properties in the excited states. By using other ultrafast X-ray facilities that will be completed in the near future, time-resolution for the excited-state structure measurements should reach the femtosecond time scales, which will make "molecular movies" of bond breaking or formation, and vibrational relaxation, a reality.

Journal Article↗