289 research outputs found

    A note on the Krylov solvability of compact normal operators on Hilbert space

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    We analyse the Krylov solvability of inverse linear problems on Hilbert space H\mathcal{H} where the underlying operator is compact and normal. Our results explicitly describe the Krylov subspace for such operators given any datum vector gHg\in\mathcal{H}, as well as prove that all inverse linear problems are Krylov solvable provided that gg is in the range of the operator. We close the study by proving an isomorphism between the closed Krylov subspace for a general bounded normal operator and an L2L^2-measure space based on the scalar spectral measure

    On Krylov Methods in Infinite-dimensional Hilbert Space

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    This thesis contains the development of key features for the solution to inverse linear problems Af = g on infinite-dimensional Hilbert space H using projection methods. Particular attention is paid to Krylov subspace methods. Intrinsic, key operator-theoretic constructs that guarantee the \u2018Krylov solvability\u2019 of the problem Af = g are developed and investigated for this class of projection methods. This theory is supported by numerous examples, counterexamples, and some numerical tests. Results for both bounded and unbounded operators on general Hilbert spaces are considered, with special attention paid to the Krylov method of conjugate-gradients in the unbounded setting

    The Adoption of Information Systems in SMEs: Organizational Issues and Success Factors

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    This research approaches the issues of introducing ICTs (Information and Communication Technologies) into Small and Medium Enterprises, with the aim of finding some conditions that make the organizational context able to manage the change process needed to really get the potential benefits of these technologies. The final objective is to propose a theoretical base for a methodology able to improve analytical and diagnostic capabilities of organizational realities before and during planning and evaluation phases of their Information Technology investments. The study is planned to go through two phases. The first one is aimed to look for reliable indicators to forecast readiness and adequacy of a specific organizational context towards the positive adoption of I.T. systems through a deep analysis of five significant cases. The second phase will test such indicators through questionnaire research on a larger sample of Italian SMEs

    ASTRONOMICAL CALIBRATION OF THE SERRAVALLIAN/TORTONIANCASE PELACANI SECTION (SICILY, ITALY)

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    We performed a cyclostratigraphic study of a sedimentary sequence (Case Pelacani section) outcropping in the south-eastern margin of Sicily (Italy) and covering the Upper Serravallian/Lower Tortonian stratigraphic interval. Calcareous plankton biostratigraphic data reported in another paper proved that all the sequence of bio-events generally reported from just below and above the S/T boundary is present in the section. They allowed a detailed correlation with the Gibliscemi section.  Preliminary paleomagnetic data suggest that a secondary remagnetization  component prevents the recognition of the correct sequence of paleomagnetic chrons along the studied interval. The sedimentary record has been compared, on the basis of an integrated calcareous plankton biostratigraphy, with that of the Gibliscemi section. Cyclostratigraphic analysis of the lithological patterns recognized throughout the succession and the application of spectral methodologies to the abundance fluctuations of the planktonic foraminifer Globigerinoides quadrilobatus highlighted the presence in the signal of the classic Milankovitch frequencies (precession, obliquity and eccentricity). Correlation of the lithological patterns and of the different frequency bands extracted by numerical filtering from the faunal record with the same components modulating the insolation curve provided an astronomic calibration of the sedimentary record and, consequently, a precise age for all the calcareous plankton bioevents recognized throughout the studied interval.&nbsp

    Endoscopic Submucosal Dissection of Gastric Neoplastic Lesions. An Italian, Multicenter Study

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    Endoscopic submucosal dissection (ESD) allows removing neoplastic lesions on gastric mucosa, including early gastric cancer (EGC) and dysplasia. Data on ESD from Western countries are still scanty. We report results of ESD procedures performed in Italy. Data of consecutive patients who underwent ESD for gastric neoplastic removal were analyzed. The en bloc resection rate and the R0 resection rates for all neoplastic lesions were calculated, as well as the curative rate (i.e., no need for surgical treatment) for EGC. The incidence of complications, the one‐month mortality, and the recurrence rate at one‐year follow‐up were computed. A total of 296 patients with 299 gastric lesions (80 EGC) were treated. The en bloc resection was successful for 292 (97.6%) and the R0 was achieved in 266 (89%) out of all lesions. In the EGC group, the ESD was eventually curative in 72.5% (58/80) following procedure. A complication occurred in 30 (10.1%) patients. Endoscopic treatment was successful in all 3 perforations, whereas it failed in 2 out of 27 bleeding patients who were treated with radiological embolization (1 case) or surgery (1 case). No procedure‐related deaths at one‐month follow‐up were observed. Lesion recurrence occurred in 16 (6.2%) patients (6 EGC and 10 dysplasia). In conclusion, the rate of both en bloc and R0 gastric lesions removal was very high in Italy. However, the curative rate for EGC needs to be improved. Complications were acceptably low and amenable at endoscopy

    Predictors of Response to Intradetrusor Botulinum Toxin-A Injections in Patients with Idiopathic Overactive Bladder

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    Objectives. To evaluate whether there are any demographic or urodynamic differences in patients with idiopathic overactive bladder (I-OAB) that respond and do not respond to intradetrusor injections of botulinum toxin-A (BTX-A). Methods. This represents a secondary analysis of data collected from an investigator initiated randomized trial designed to evaluate clinical differences in outcomes for 100 versus 150 U BTX-A in patients with I-OAB. Preinjection demographic and urodynamic data were collected. Patients were evaluated 12 weeks after injection and were determined to be responders or nonresponders as defined by our criteria. Statistical comparisons were made between groups. Results. In patients with overactive bladder without incontinence (OAB-Dry), there were no variables that could be used to predict response to BTX-A. On univariate analysis, younger patients with overactive bladder with incontinence (OAB-Wet) were more likely to respond to BTX-A than older patients. However, this relationship was no longer statistically significant on multivariate analysis. Conclusions. We were unable to identify any preinjection demographic or urodynamic parameters that could aid in predicting which patients will achieve clinical response to BTX-A. Future studies are necessary to further evaluate this question

    Integration of Live Radio Programming & Real-time Blogging in the Macaulay Honors College Seminar III on Science and Technology in New York City

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    In this presentation we summarize the lessons learnt through this experience of including live radio programming activities in the context of Macaulay Honors College Seminar III on Science and Technology in New York City. Our presentation falls under the innovation theme and specifically the blended learning opportunities track. The overall goal of the Macaulay Honors College Seminar III is to offer students fundamental scientific and technological knowledge. An essential aspect of our approach was to afford Honors students a real opportunity to interface directly with the actual people involved in science and technology. We arranged for live radio interviews, as well as for pre-recorded ones with -among others- Nobel Laureates, innovators, entrepreneurs, technology-transfer officers from major Universities, and science and technology commentators from the mass media. During the first year of this project, Honors students were assigned pre-existing audio archives of interviews. Students produced a report of 1000-1500 words describing the scientific concepts behind the work of each interviewee. In the second year the class experience was upgraded to live radio programming. Honors students were situated in a “green room” with laptops and blogged questions in real time to the interviewees. A student representative was the instructor’s co-host of the radio program. This programming was realized in the studios of WHCR 90.3 FM, a community radio station broadcasting from the campus of the City College of New York. During the third year of the project the same facilities were used for video-taping interviews among students. We focused on Nobel Laureates who claim City College of New York as their alma mater. We conclude that our approach is sustainable since the available technology allows most students to capture as an audio file or a video file the topic in consideration. Preparing a broadcast entails unique challenges not common in traditional class settings. We also concluded that our approach is measurable since students responsible for a variety of topics were able to follow-up with several interviewees. In some instances students were awarded an internship through the interviewees. This was measurable in that most of this material was archived on respective course websites complete with public commenting and indications for “number of hits” or “number of views.” We consider our approach scalable due to the ever expanding on-line platforms of most CUNY campuses
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