4,723 research outputs found

    Ballisticity of nanotube FETs: Role of phonon energy and gate bias

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    We investigate the role of electron-phonon scattering and gate bias in degrading the drive current of nanotube MOSFETs. Our central results are: (i) Optical phonon scattering significantly decreases the drive current only when gate voltage is higher than a well-defined threshold. It means that elastic scattering mechanisms are most detrimental to nanotube MOSFETs. (ii) For comparable mean free paths, a lower phonon energy leads to a larger degradation of drive current. Thus for semiconducting nanowire FETs, the drive current will be more sensitive than carbon nanotube FETs because of the smaller phonon energies in semiconductors. (iii) Radial breathing mode phonons cause an appreciable reduction in drive current.Comment: 16 pages, 1 table, 4 figure

    Evaluasi Struktur Gedung X di Jakarta Berdasarkan Sni 03-1726-2012 Ketahanan Gempa untuk Struktur Gedung

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    Wilayah Jakarta berada pada zonasi gempa menengah berdasarkan peta zonasi gempa 2010 yang dipublikasikan oleh Pusat Penelitian dan Pengembangan Pemukiman (PUSKIM), Kementrian Pekerjaan Umum. Tujuan penelitian ini adalah merekomendasikan perkuatan struktur pada eksisting gedung X di Jakarta, agar ketika gempa datang, struktur gedung tersebut tetap mampu memikul beban ultimit. Objek penelitian merupakan gedung kategori high rise building, memiliki jumlah lantai lebih dari 10, dibangun sebelum tahun 2010, berlokasi pada kelas situs tanah lunak dan secara visual terindikasi adanya kerusakan pada elemen struktur. Pemodelan struktur gedung X didesain dan dianalisis menggunakan program ETABS. Pembebanan gempa diberikan secara dinamik menggunakan prosedur analisis spektrum respons ragam. Hasil analisis story drift menunjukan bahwa gedung X dinyatakan aman terhadap kinerja batas ultimit yang telah dihitung berdasarkan pedoman gempa SNI 03-1726-2012. Nilai maksimum simpangan antar lantai pada gedung X untuk arah-x sebesar 68,60 mm dan arah-y sebesar 101,2 mm. Bagaimanapun, hasil analisis struktur pemodelan gedung X pada ETABS menunjukkan bahwa terdapat beberapa elemen balok dan kolom yang membutuhkan perkuatan struktur. Perkuatan elemen balok direncanakan menggunakan CFRP yang dihitung keamanannya berdasarkan pedoman ACI 440.2R-8 Perkuatan elemen kolom direncanakan menggunakan Concrete Jacketing yang dianalisis melalui section designer pada program ETABS dan dihitung keamanannya berdasarkan pedoman SNI 03-2847-2013

    Multi-level Multi-objective Quadratic Fractional Programming Problem with Fuzzy Parameters: A FGP Approach

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    The motivation behind this paper is to present multi-level multi-objective quadratic fractional programming (ML-MOQFP) problem with fuzzy parameters in the constraints. ML-MOQFP problem is an important class of non-linear fractional programming problem. These type of problems arise in many fields such as production planning, financial and corporative planning, health care and hospital planning. Firstly, the concept of the -cut and fuzzy partial order relation are applied to transform the set of fuzzy constraints into a common crisp set. Then, the quadratic fractional objective functions in each level are transformed into non-linear objective functions based on a proposed transformation. Secondly, in the proposed model, separate non-linear membership functions for each objective function of the ML-MOQFP problem are defined. Then, the fuzzy goal programming (FGP) approach is utilized to obtain a compromise solution for the ML-MOQFP problem by minimizing the sum of the negative deviational variables. Finally, an illustrative numerical example is given to demonstrate the applicability and performance of the proposed approach

    Late removal of retrievable caval filters.

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    The advent of retrievable caval filters was a game changer in the sense, that the previously irreversible act of implanting a medical device into the main venous blood stream of the body requiring careful evaluation of the pros and cons prior to execution suddenly became a "reversible" procedure where potential hazards in the late future of the patient lost most of their weight at the time of decision making. This review was designed to assess the rate of success with late retrieval of so called retrievable caval filters in order to get some indication about reasonable implant duration with respect to relatively "easy" implant removal with conventional means, i.e., catheters, hooks and lassos. A PubMed search (www.pubmed.gov) was performed with the search term "cava filter retrieval after 30 days clinical", and 20 reports between 1994 and 2013 dealing with late retrieval of caval filters were identified, covering approximately 7,000 devices with 600 removed filters. The maximal duration of implant reported is 2,599 days and the maximal implant duration of removed filters is also 2,599 days. The maximal duration reported with standard retrieval techniques, i.e., catheter, hook and/or lasso, is 475 days, whereas for the retrievals after this period more sophisticated techniques including lasers, etc. were required. The maximal implant duration for series with 100% retrieval accounts for 84 days, which is equivalent to 12 weeks or almost 3 months. We conclude that retrievable caval filters often become permanent despite the initial decision of temporary use. However, such "forgotten" retrievable devices can still be removed with a great chance of success up to three months after implantation. Conventional percutaneous removal techniques may be sufficient up to sixteen months after implantation whereas more sophisticated catheter techniques have been shown to be successful up to 83 months or more than seven years of implant duration. Tilting, migrating, or misplaced devices should be removed early on, and replaced if indicated with a device which is both, efficient and retrievable

    New Algorithm for Drawings of 3-Planar Graphs

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    Graphs arise in a natural way in many applications, together with the need to be drawn. Except for very small instances, drawing a graph by hand becomes a very complex task, which must be performed by automatic tools. The field of graph drawing is concerned with finding algorithms to draw graph in an aesthetically pleasant way, based upon a certain number of aesthetic criteria that define what a good drawing, (synonyms: diagrams, pictures, layouts), of a graph should be. This problem can be found in many such as in the computer networks, data networks, class inter-relationship diagrams in object oriented databases and object oriented programs, visual programming interfaces, database design systems, software engineering…etc. Given a plane graph G, we wish to find a drawing of G in the plane such that the vertices of G are represented as grid points, and the edges are represented as straight-line segments between their endpoints without any edge-intersection. Such drawings are called planar straight-line drawings of G. An additional objective is to minimize the area of the rectangular grid in which G is drawn. In this paper we introduce a new algorithms that finds an embedding of 3-planar graph. Keywords: 3- Planar Graph; Graph Drawing; drawing on grid

    Non-equilibrium Green's function treatment of phonon scattering in carbon nanotube transistors

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    We present the detailed treatment of dissipative quantum transport in carbon nanotube field-effect transistors (CNTFETs) using the non-equilibrium Green's function formalism. The effect of phonon scattering on the device characteristics of CNTFETs is explored using extensive numerical simulation. Both intra-valley and inter-valley scattering mediated by acoustic (AP), optical (OP), and radial breathing mode (RBM) phonons are treated. Realistic phonon dispersion calculations are performed using force-constant methods, and electron-phonon coupling is determined through microscopic theory. Specific simulation results are presented for (16,0), (19,0), and (22,0) zigzag CNTFETs that are in the experimentally useful diameter range. We find that the effect of phonon scattering on device performance has a distinct bias dependence. Up to moderate gate biases the influence of high-energy OP scattering is suppressed, and the device current is reduced due to elastic back-scattering by AP and low-energy RBM phonons. At large gate biases the current degradation is mainly due to high-energy OP scattering. The influence of both AP and high-energy OP scattering is reduced for larger diameter tubes. The effect of RBM mode, however, is nearly independent of the diameter for the tubes studied here.Comment: 52 pages, 1 table, 9 figure

    Concurrent Acquisition of a Single Nucleotide Polymorphism in Diverse Influenza H5N1 Clade 2.2 Sub-clades

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    Highly pathogenic Influenza A H5N1 was first identified in Guangdong Province in 1996, followed by human cases in Hong Kong in 1997 1,2. The number of confirmed human cases now exceeds 300 and the associated Case Fatality Rate exceeds 60% 3. The genetic diversity of the serotype continues to increase. Four distinct clades or sub-clades have been linked to human cases 4-7. The gradual genetic changes identified in the sub-clades have been attributed to copy errors by viral encoded polymerases that lack an editing function, thereby resulting in antigenic drift 8. We report here the concurrent acquisition of the same polymorphism by multiple, genetically distinct, clade 2.2 sub-clades in Egypt, Russia, Kuwait, and Ghana. These changes are not easily explained by the current theory of “random mutation” through copy error, and are more easily explained by recombination with a common source. The recombination role is further supported by the high fidelity replication in swine influenza 9 and aggregation of single nucleotide polymorphisms in H5N1 clade 2.2 hemagglutinin 10

    Local variation in helminth burdens of Egyptian spiny mice (Acomys cahirinus dimidiatus) from ecologically similar sites: relationships with hormone concentrations and social behaviour

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    Populations of Egyptian spiny mice (Acomys cahirinus dimidiatus) in a fragmented montane wadi system in the Sinai showed significant differences in the abundance of gut helminths. Differences in parasite load between populations were positively associated with measures of androgen activity but showed no significant relationship with glucocorticoid activity. Social discrimination tests with adult males from different wadis showed that those from sites with greater helminth abundance were less likely to investigate odours from other males and were less aggressive when subsequently interacting with the odour donors. Subjects showed markedly more investigation towards the odours of males from distant wadis compared with those from their own or immediately neighbouring wadi, but were less aggressive when confronted with odour donors from distant wadis. Despite this, there was a positive relationship between the amount of investigation towards distant male odour and subsequent aggression towards the male. While aggressiveness was positively associated with measures of androgen and glucocorticoid activity, no significant relationship emerged with individual helminth infection. Thus aggressiveness appeared to relate to overall local population levels of infection rather than individual challenge

    Prognostic Impact of Previous Percutaneous Coronary Intervention on the Outcome of Coronary Artery Bypass Grafting in Multivessel Disease Diabetic Patients

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    Background: Previous studies suggest that patients who receive percutaneous coronary intervention (PCI) are at a higher risk of undergoing coronary artery bypass grafting (CABG). This study aimed to investigate the risk of CABG in patients with a history of PCI. Methods: One hundred diabetic patients who underwent CABG from October 2020 to February 2022 were enrolled and divided into two groups. Group I consisted of 50 patients with no prior PCI, while Group II comprised 50 patients with a history of PCI. Results: The mean age was 57.4 ± 8.67 years for Group I and 59.72 ± 7.5 years for Group II (p= 0.155). The mean cardiopulmonary bypass time was 108.56 ± 34.53 minutes for Group I and 127.4 ± 35.93 minutes for Group II (p=0.009). The ischemic duration was 75.68 ± 19.94 minutes for Group I and 75.12± 23.02 minutes for Group II. The mean number of grafts was greater in Group I (3.5 (3 – 3.5) vs. 3 (2 – 4), p= 0.011). The mean ventilation time was 9 (5 – 13.75) hours for Group I and 10 (5 – 19) hours for Group II. The mean length of ICU stay was 1 (1–2) day for Group I and 2 (2–3) days for Group II (p<0.001). The length of hospital stay was 8 (7–9) days for Group I and 10 (9–11) days for Group II (p<0.001). There were statistically significant differences between the groups in terms of MACE (higher in the PCI group, p=0.046), improvement in wall motion abnormalities (higher in the non-PCI group, p=0.007), and postoperative normal ejection fraction (higher in the non-PCI group, p=0.032). There was no significant difference in hospital mortality between the two groups (0 vs 3), with a p value =0.07. Conclusion: A previous PCI could increase post-CABG morbidity and MACEs. However, no significant difference in postoperative mortality rates was found between patients who underwent prior PCI and those who did not
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