Inverse M-matrices, II

AbstractThis is an update of the 1981 survey by the first author. In the meantime, a considerable amount has been learned about the very special structure of the important class of inverse M-matrices. Developments since the earlier survey are emphasized, but we have tried to be somewhat complete; and, some results have not previously been published. Some proofs are given where appropriate and references are given for others. After some elementary preliminaries, results are grouped by certain natural categories

HIV/STI co-infection among men who have sex with men in Spain

In Spain, neither the HIV nor the STI national surveillance systems collect information on HIV/STI co-infection. However, there are two networks based on HIV/STI clinics which gather this data. We describe HIV prevalence in men who have sex with men (MSM) diagnosed with infectious syphilis and/or gonorrhoea in 15 STI clinics; and concurrent diagnoses of STI in MSM newly diagnosed with HIV in 19 HIV/STI clinics. In total, 572 MSM were diagnosed with infectious syphilis and 580 with gonorrhoea during 2005-2007. HIV prevalence among syphilis and gonorrhoea cases was 29.8% and 15.2% respectively. In the multivariate analysis, HIV/syphilis co-infection was associated with being Latin American; having a history of STI; reporting exclusively anal intercourse; and having sex with casual or several types of partners. HIV and gonorrhoea co-infection was associated with age older than 45 years; having no education or only primary education completed; and having a history of STI. In total, 1,462 HIV infections were newly diagnosed among MSM during 2003-2007. Of these, 31.0% were diagnosed with other STI at the same time. Factors associated with STI co-infection among new HIV cases in MSM were being Latin American; and having sex with casual partners or with both steady and casual partners. In Spain, a considerable proportion of MSM are co-infected with HIV and STI.This work was funded by two grants (36646/07; 36794/08) from the Foundation for Research and Prevention of AIDS in Spain (Fundación para la Investigación y la Prevención del SIDA en España–FIPSE).S

Hybrid system for plagiarism detection

The Internet boom in recent years has increased the interest in the field of plagiarism detection. A lot of documents are published on the Net everyday and anyone can access and plagiarize them. Of course, checking all cases of plagiarism manually is an unfeasible task. Therefore, it is necessary to create new systems that are able to automatically detect cases of plagiarism produced. In this paper, we introduce a new hybrid system for plagiarism detection which combines the advantages of the two main plagiarism detection techniques. This system consists of two analysis phases: the first phase uses an intrinsic detection technique which dismisses much of the text, and the second phase employs an external detection technique to identify the plagiarized text sections. With this combination we achieve a detection system which obtains accurate results and is also faster thanks to the prefiltering of the text

Novel Electronic Devices in Macroporous Silicon: Design of FET Transistors for Power Applications

In this paper, we study the application of macroporous silicon (MpSi) to the fabrication of transistors: Four different FET transistor structures are proposed using MpSi as the base material. These devices have been studied by simulation, and their characteristics are shown herein. The proposed structures include JFET, MOSFET, and trio de-like devices; in this study, we have considered both vertical and horizontal structures. For the vertical case, the proposed devices use the MpSi tubes to create the channel, filling them with a semiconductor and using the bulk silicon as a cylindrical gate all around. In contrast, for the horizontal transistors, the MpSi structure is used as the channel medium, while the conductor-filled pores serve as the controlling gate, thus obtaining a trio de-like device. The use of MpSi allows one to obtain large transistor arrays of extremely high density, thus obtaining a large amount of parallel devices in a moderate-to-small device area. Even more, pore engineering introduces a degree of freedom in the design of the transistor characteristics. We show that the proposed devices have a low threshold voltage and can support large currents. Finally, the behavior of these structures is studied for different geometries.Peer ReviewedPostprint (published version

Novel Electronic Devices in Macroporous Silicon: Design of FET Transistors for Power Applications

In this paper, we study the application of macroporous silicon (MpSi) to the fabrication of transistors: Four different FET transistor structures are proposed using MpSi as the base material. These devices have been studied by simulation, and their characteristics are shown herein. The proposed structures include JFET, MOSFET, and trio de-like devices; in this study, we have considered both vertical and horizontal structures. For the vertical case, the proposed devices use the MpSi tubes to create the channel, filling them with a semiconductor and using the bulk silicon as a cylindrical gate all around. In contrast, for the horizontal transistors, the MpSi structure is used as the channel medium, while the conductor-filled pores serve as the controlling gate, thus obtaining a trio de-like device. The use of MpSi allows one to obtain large transistor arrays of extremely high density, thus obtaining a large amount of parallel devices in a moderate-to-small device area. Even more, pore engineering introduces a degree of freedom in the design of the transistor characteristics. We show that the proposed devices have a low threshold voltage and can support large currents. Finally, the behavior of these structures is studied for different geometries.Peer Reviewe