379 research outputs found
Comparative Evaluation of Spatial Features in Automatic Land Use Classification from Photographic Imagery
Five spatial features have been evaluated for their applicability in automatic land use classification of photographic imagery. Data arrays of approximately 10,000 square meters were classified on the basis of an 8 by 8 point data array. Statistical features, information features, sequency features and texture features were evaluated using a distance to prototype classifier and an adaptive classifier. The results indicate approximately 70% accuracy in the classification
Dissipation in Quasi One-Dimensional Superconducting Single-Crystal Sn Nanowires
Electrical transport measurements were made on single-crystal Sn nanowires to
understand the intrinsic dissipation mechanisms of a one-dimensional
superconductor. While the resistance of wires of diameter larger than 70 nm
drops precipitately to zero at Tc near 3.7 K, a residual resistive tail
extending down to low temperature is found for wires with diameters of 20 and
40 nm. As a function of temperature, the logarithm of the residual resistance
appears as two linear sections, one within a few tenths of a degree below Tc
and the other extending down to at least 0.47 K, the minimum temperature of the
measurements. The residual resistance is found to be ohmic at all temperatures
below Tc of Sn. These findings are suggestive of a thermally activated phase
slip process near Tc and quantum fluctuation-induced phase slip process in the
low temperature regime. When the excitation current exceeds a critical value,
the voltage-current (V-I) curves show a series of discrete steps in approaching
the normal state. These steps cannot be fully understood with the classical
Skocpol-Beasley-Tinkham phase slip center model (PSC), but can be qualitatively
accounted for partly by the PSC model modified by Michotte et al.Comment: 7 pages, 5 figures. To be appeared on Physical Review B 71, 200
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Principles of logic design
This study involves logic design and switching theory, in particular their practical application to the logic design and understanding of digital machines. Digital machines, of course, play an extremely important role in that large class of machines known as digital computers. But they also play an important role in many other kinds of practical devices important in the design of communications systems, digital control systems, counters, registers, digital meters, and so on.
The basic content of switching theory is very simple. It embodies that body of machines and machine behavior that can be realized with "switches", things that are either "on" or "off", and nothing, really, could be much simpler than that. Of course the world is really comprised of very many complex structures which are really composed of exceedingly simple lesser structures, so that we really shouldn't be too surprised that even though the elements of switching theory are quite simple, their consequences are not necessarily so.
The goals of our study are several, and include at least the following:
1) to develop some understanding and capability in using the techniques, design procedures, and models that have been developed for understanding and designing digital networks;
2) to explore in some modest detail the kinds of questions with which logic designers and practitioners concern themselves;
3) to develop an appreciation for the tremendous variation possible in digital design requirements and specifications, i. e,, for the complexity of the 'finite' digital problem, and hence an understanding of the need for systematic design techniques by which to attack such problems;
4) to gain some practice with the fundamental tools and techniques of logic design I so that the reader can adapt the techniques to the "new" problem presented by his own particular design constraints; and
5) to provide an introduction to the literature so that the discerning student can, in the future, dip into the ever growing literature in the field, and find it to some degree comprehensible, and advantageous to use
Technical challenges of providing record linkage services for research
Background: Record linkage techniques are widely used to enable health researchers to gain event based longitudinal information for entire populations. The task of record linkage is increasingly being undertaken by specialised linkage units (SLUs). In addition to the complexity of undertaking probabilistic record linkage, these units face additional technical challenges in providing record linkage ‘as a service’ for research. The extent of this functionality, and approaches to solving these issues, has had little focus in the record linkage literature. Few, if any, of the record linkage packages or systems currently used by SLUs include the full range of functions required. Methods: This paper identifies and discusses some of the functions that are required or undertaken by SLUs in the provision of record linkage services. These include managing routine, on-going linkage; storing and handling changing data; handling different linkage scenarios; accommodating ever increasing datasets. Automated linkage processes are one way of ensuring consistency of results and scalability of service. Results: Alternative solutions to some of these challenges are presented. By maintaining a full history of links, and storing pairwise information, many of the challenges around handling ‘open’ records, and providing automated managed extractions are solved. A number of these solutions were implemented as part of the development of the National Linkage System (NLS) by the Centre for Data Linkage (part of the Population Health Research Network) in Australia.Conclusions: The demand for, and complexity of, linkage services are growing. This presents as a challenge to SLUs as they seek to service the varying needs of dozens of research projects annually. Linkage units need to be both flexible and scalable to meet this demand. It is hoped the solutions presented here can help mitigate these difficulties
Frequency and type of adverse analytical findings in athletics: Differences among disciplines.
Athletics is a highly diverse sport that contains a set of disciplines grouped into jumps,
throws, races of varying distances, and combined events. From a physiological standpoint,
the physical capabilities linked to success are quite different among
disciplines, with varying involvements of muscle strength, muscle power, and
endurance. Thus, the use of banned substances in athletics might be dictated by physical
dimensions of each discipline. Thus, the aim of this investigation was to
analyse the number and distribution of adverse analytical findings per drug class in
athletic disciplines. The data included in this investigation were gathered from the
Anti-Doping Testing Figure Report made available by the World Anti-Doping Agency
(from 2016 to 2018). Interestingly, there were no differences in the frequency of
adverse findings (overall, 0.95%, range from 0.77 to 1.70%) among disciplines
despite long distance runners having the highest number of samples analysed per year
( 9812 samples/year). Sprinters and throwers presented abnormally high
proportions of adverse analytical findings within the group of anabolic agents
(p < 0.01); middle- and long-distance runners presented atypically high proportions of
findings related to peptide hormones and growth factors (p < 0.01); racewalkers presented
atypically high proportions of banned diuretics and masking agents (p = 0.05).
These results suggest that the proportion of athletes that are using banned substances
is similar among the different disciplines of athletics. However, there are substantial
differences in the class of drugs more commonly used in each discipline. This information
can be used to effectively enhance anti-doping testing protocols in athletics.post-print1.911 K
Altered Desaturation and Elongation of Fatty Acids in Hormone-Sensitive Lipase Null Mice
Hormone-sensitive lipase (HSL) is expressed predominantly in adipose tissue, where it plays an important role in catecholamine-stimulated hydrolysis of stored lipids, thus mobilizing fatty acids. HSL exhibits broad substrate specificity and besides acylglycerides it hydrolyzes cholesteryl esters, retinyl esters and lipoidal esters. Despite its role in fatty acid mobilization, HSL null mice have been shown to be resistant to diet-induced obesity. The aim of this study was to define lipid profiles in plasma, white adipose tissue (WAT) and liver of HSL null mice, in order to better understand the role of this multifunctional enzyme
IRF4 Is a Suppressor of c-Myc Induced B Cell Leukemia
Interferon regulatory factor 4 (IRF4) is a critical transcriptional regulator in B cell development and function. We have previously shown that IRF4, together with IRF8, orchestrates pre-B cell development by limiting pre-B cell expansion and by promoting pre-B cell differentiation. Here, we report that IRF4 suppresses c-Myc induced leukemia in EμMyc mice. Our results show that c-Myc induced leukemia was greatly accelerated in the IRF4 heterozygous mice (IRF4+/−Myc); the average age of mortality in the IRF4+/−Myc mice was only 7 to 8 weeks but was 20 weeks in the control mice. Our results show that IRF4+/−Myc leukemic cells were derived from large pre-B cells and were hyperproliferative and resistant to apoptosis. Further analysis revealed that the majority of IRF4+/−Myc leukemic cells inactivated the wild-type IRF4 allele and contained defects in Arf-p53 tumor suppressor pathway. p27kip is part of the molecular circuitry that controls pre-B cell expansion. Our results show that expression of p27kip was lost in the IRF4+/−Myc leukemic cells and reconstitution of IRF4 expression in those cells induced p27kip and inhibited their expansion. Thus, IRF4 functions as a classical tumor suppressor to inhibit c-Myc induced B cell leukemia in EμMyc mice
No Major Change in vCJD Agent Strain after Secondary Transmission via Blood Transfusion
The identification of transmission of variant Creutzfeldt-Jakob disease (vCJD) by blood transfusion has prompted investigation to establish whether there has been any alteration in the vCJD agent following this route of secondary transmission. Any increase in virulence or host adaptation would require a reassessment of the risk analyses relating to the possibility of a significant secondary outbreak of vCJD. Since there are likely to be carriers of the vCJD agent in the general population, there is a potential for further infection by routes such as blood transfusion or contaminated surgical instruments.We inoculated both wild-type and transgenic mice with material from the first case of transfusion associated vCJD infection.The strain transmission properties of blood transfusion associated vCJD infection show remarkable similarities to the strain of vCJD associated with transmission from bovine spongiform encephalopathy (BSE).Although it has been hypothesized that adaptation of the BSE agent through secondary passage in humans may result in a greater risk of onward transmission due to an increased virulence of the agent for humans, our data presented here in two murine models suggest no significant alterations to transmission efficiency of the agent following human-to-human transmission of vCJD
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