130,883 research outputs found
Low noise charge sensitive preamplifier dc stabilized without a physical resistor
No full textThe invention is a novel charge sensitive preamplifier (SCP) which has no resistor in parallel with the feedback capacitor. No resetting circuit is required to discharge the feedback capacitor. The DC stabilization of the preamplifier is obtained by means of a second feedback loop between the preamplifier output and the common base transistor of the input cascode. The input transistor of the preamplifier is a JFET with the gate-source junction forward biased. The detector leakage current flows into this junction. In particular, this invention, in addition to eliminating the feedback resistor, eliminates the need for external devices between the detector and the preamplifier, and it eliminates the need for external circuitry to sense the output voltage and reset the CSP. Furthermore, the noise level of the novel CSP is very low, comparable with the performance achievable with other more complex solutions
General Purpose software for Probability Computations: a Virtual Machine Approach
No full textThe structure of a computer is used as model for software architecture; the resulting system, guided by a purposely developed problem oriented language, is designed for applying probability methods to structural reliability and safety problems
Recommended from our members
Keeping the learning in learning objects
No full textRecognising the fact that learning objects are still a new concept, D. Rehak and R. Mason have tackled the significant issue of how to make learning objects work in practice in a very interesting and thorough manner. They clearly state that the topic of learning objects is rather new and in an experimental phase. There is an agreement about the attributes of a learning object (reusability, accessibility, interoperability-portability, duration) within the learning technology community. However, stakeholders see the usefulness of learning objects from different optical angles: on the one hand, the training sector tends to be engaged in reuse and just-in-time/on-demand content aggregation in order to augment their market share; on the other hand universities and the learning sector in general, consider the reuse and repurposing of learning material as a big opportunity to save resources as well as to offer new (more enhanced) learning experiences.
The authors analyse the concept of learning objects in five stages which are common for new concepts in any domain. Along the presentation of these stages (confusions, stakeholders, precedents, investigations of how to apply and exploit, acceptance), they pinpoint several crucial issues that need to be tackled in order that the learning process will take benefit of the notion of learning objects
Sistemi esperti e loro applicazioni in ingegneria civile
No full textL'articolo discute e prospetta le possibililtà di applicazioni innovative nel campo dell'intelligenza artificiale ad alcuni settori dell'ingegneria strutturale e sismica
Native and non-native processing of morphologically complex English words: testing the influence of derivational prefixes
No full textThis paper reports results of a replication and extension of Silva & Clahsen (2008). We used the masked priming paradigm (Forster & Davis, 1984) to measure differences in native and non-native processing of morphologically complex English words. Three groups of participants took part in these experiments: one native English speaker control group, and advanced adult learners of English as a second language (L2) with Spanish or Mandarin Chinese as their first language (L1).We compared the reaction times provided by lexical decision tasks to determine differences in the processing of five different morphemes. The critical items for our Experiments 1 - 3 were the same variables tested in Silva & Clahsen (2008): the regular past tense inflectional suffix -ed and the derivational suffixes -ness and -ity. We included two experiments to investigate the nature of native and non-native processing of the derivational prefixes, un- and re-.Silva & Clahsen (2008) assert that non-native speakers rely on the declarative memory system to process morphologically complex words. They found full priming for native English speakers for both inflectional and derivational suffixes; however, their non-native English speaking participants showed no priming effects for the inflectional suffix -ed and partial priming effects for the derivational suffixes -ness and -ity. Based on these results, Silva & Clahsen (2008) claim that L2 speakers process inflectional and derivational morphology differently. The results of this study are inconsistent with Silva & Clahsen (2008) for two of the affixes tested: the inflectional -ed and the derivational suffix -ity. Our Spanish L2 participants exhibited full priming effects for the inflectional -ed suffix, which suggests that the Spanish L2 participants are accessing the procedural memory system when processing English verbs in the simple past. Additionally, the Spanish L2 group in this study provided significantly faster reaction times for the derivational suffix, -ity than the Mandarin Chinese L2 group. Since -ity is a Latinate suffix and Spanish a Latin language, we believe our Spanish L2 participants are transferring knowledge of L1 morphology when processing morphologically complex words in their L2, which Silva & Clahsen (2008) claim is not a factor in second language processing
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
An Ultra Low-Noise Preamplifier For Room Temperature X-Ray Detectors
No full textABSTRACTA new circuital configuration for the charge amplifier is presented. By means of a double feedback loop, the input field-effect transistor can operate with its gate junction sligtly forward biased, collecting the detector current and discharging the feedback capacitor. The feedback resistor is so avoided and no resetting device or circuit is required for the preamplifier operation. The noise is limited by the input transistor, an equivalent noise charge of 19.5 r.m.s. electrons has been measured at room temperature by employing a commercial JFET.</jats:p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
- …
