1,059 research outputs found
RAM-Efficient External Memory Sorting
In recent years a large number of problems have been considered in external
memory models of computation, where the complexity measure is the number of
blocks of data that are moved between slow external memory and fast internal
memory (also called I/Os). In practice, however, internal memory time often
dominates the total running time once I/O-efficiency has been obtained. In this
paper we study algorithms for fundamental problems that are simultaneously
I/O-efficient and internal memory efficient in the RAM model of computation.Comment: To appear in Proceedings of ISAAC 2013, getting the Best Paper Awar
Propane Dehydrogenation Using Transition Metal Cluster Catalysts
Our research seeks to determine the propane dehydrogenation (PDH) reaction pathways using various transition-metal cluster catalysts. We are studying the first step of the reaction, in which a C-H bond is broken. This has been previously shown to be the rate-limiting step of the PDH reaction. We are calculating the PDH activation energy (Ea) using the Vienna Ab-Initio Simulation Package (VASP) in conjunction with the nudged elastic band algorithm. Thus far, we have studied Pt, Ta, and Ni clusters ranging in size from 2-10 atoms. Our goal is to better understand the dependence of Ea on metal type and cluster size
HEAVY METALS IN CULTIVATED SOIL AND PLANTS OF DAMOUR URBAN AREA - LEBANON
Παρουσιάζονται για πρώτη φορά δεδομένα συγκεντρώσεων βαρέων μετάλλων στο έδαφος και καλλιέργειες της περιοχής Νταμούρ Λιβάνου. Μετρήθηκαν οι ψευδοολικές και κινητοποιήσιμες συγκεντρώσεις των Zn, Cu, Ni, Cr, Co, Mn, Fe, Ba, Pb και Cd σε δείγματα εδαφών καθώς και οι αντίστοιχες ολικές συγκεντρώσεις των ίδιων στοιχείων σε φυτικούς ιστούς λαχανικών που καλλιεργούνται στην περιοχή Δεν ανιχνεύθηκαν συγκεντρώσεις των μη απαραίτητων στοιχείων Pb και Asενώ αυτές των υπόλοιπων στοιχείων που μελετήθηκαν βρίσκονται εντός των φυσιολογικών ορίων. Οι συγκεντρώσεις στο έδαφος φαίνεται να επηρεάζονται από την προηγούμενη χρήση γης και αυτές στα φυτά φαίνεται να ρυθμίζονται μέσω της λειτουργίας σύνθετων μεταβολικών μηχανισμών.Preliminary data on heavy metals concentrations in soil and edible plants of DamourLebanon are presented for the first time. Concentration ranges of Zn, Cu, Ni, Cr, Co, Mn, Fe, Ba, Pb and Cd in soils and vegetables collected from urban allotments in Damour were determined and assessed taking into account the pseudototal (extracted by aqua regia) and mobilizable (0.43 M acetic acid extractable) concentrations of the elements in the rhizosphere soil of the plants as well as the total concentrations in edible plant tissue. Average elemental concentrations in urban allotments are low in general. No detectable concentrations of the non-essential heavy metals Pb and As were measured in the studied plants while concentrations of micronutrient elements in plants were within normal ranges. The collected data indicate that previous land use is an important factor controlling heavy metal content in soil and that there is a complex mechanism controlling micronutrient uptake by plants
INTERACTION OF HEAVY METALS IN THE SOIL-PLANT SYSTEM OF URBAN GARDENS IN ATHENS, GREECE
Παρουσιάζονται προκαταρκτικά δεδομένα που αφορούν την αλληλεπίδραση μεταξύ εδάφους και βρώσιμων φυτών ως προς τις συγκεντρώσεις βαρέων μετάλλων στην πόλη των Αθηνών. Προσδιορίστηκε το εύρος των συγκεντρώσεων των στοιχείων Zn, Cu, Ni, Cr, Co, Mn, Fe, Ba, Pb και Cd σε εδάφη και φυτά αστικών καλλιεργειών περιοχών της Αθήνας και συγκεκριμένα μελετήθηκε το ψευδο-ολικό περιεχόμενο (εξαγωγή με βασιλικό ύδωρ) και το κινητοποιήσιμο (εξαγωγή με 0.43 Μ οξικό οξύ) κλάσμα των στοιχείων στο έδαφος καθώς και η ολική συγκέντρωση των στοιχείων στους φυτικούς ιστούς. Οι εδαφικές συγκεντρώσεις που μετρήθηκαν είναι γενικά χαμηλότερες αυτών που αναφέρονται για τα εδάφη της ευρύτερης περιοχής της Αθήνας. Οι συγκεντρώσεις των μη απαραίτητων ιχνοστοιχείων Pb και Cd δεν ανιχνεύτηκαν στα φυτικά δείγματα, ενώ αυτές των μικροθρεπτικών κυμαίνονται σε κανονικά πλαίσια. Τα δεδομένα καταδεικνύουν τη σημασία της προηγούμενης χρήσης γης στον καθορισμό των επιπέδων συγκέντρωσης των στοιχείων στο έδαφος και την περιπλοκότητα των μηχανισμών που ελέγχουν την απορρόφηση των στοιχείων από τα φυτά.Preliminary data on the interaction between soil and edible plants with respect to heavy metal concentrations in Athens, Greece are presented. Concentration ranges of Zn, Cu, Ni, Cr, Co, Mn, Fe, Ba, Pb and Cd in soils and vegetables collected from urban allotments in Athens are determined and assessed taking into account the pseudototal (extracted by aqua regia) and mobilizable (0.43 M acetic acid extractable) concentrations of the elements in the rhizosphere soil of the collected plants as well as the total concentrations in plant tissue. Average elemental concentrations in urban allotments are lower than the ones previously reported for Athens urban soil. No detectable concentrations of the non essential heavy metals Pb and Cd were measured in the studied plants while concentrations of micronutrient elements in plants are within normal ranges. The collected data indicate that previous land use is an important factor controlling heavy metal content in soil and that there is a complex mechanism controlling micronutrient uptake by plants
Pengembangan Sistem Informasi Panduan Mitigasi Bencana Alam Provinsi Sumatera Barat Berbasis Android
Sumatera Barat adalah salah satu provinsi di Indonesia yang bila dilihat dari potensi bencana berdasarkan data BNPB, adalah wilayah dengan potensi bahaya yang tinggi. Bencana dapat terjadi kapan saja dan di mana saja sehingga orang perlu meningkatkan kewaspadaan, kesadaran, dan kesiapan yang biasa disebut masyarakat tanggap bencana. Seiring dengan pesatnya kemajuan teknologi seluler, diperlukan aplikasi yang mengakomodasi kebutuhan masyarakat untuk aplikasi yang dapat memberikan informasi terkini tentang mitigasi disater secara efektif dan efisien. Tujuan dari proyek akhir ini adalah untuk mengembangkan sistem panduan informasi bencana alam yang dapat membantu orang dalam mencari informasi tentang panduan mitigasi bencana, berita & peristiwa mitigasi, pelaporan bencana & layanan pertanyaan bencana, dan menyediakan lokasi BPBD dan rute evakuasi menggunakan Google Map API . Tugas akhir ini menghasilkan sistem informasi panduan mitigasi bencana alam berupa situs web pada server dan aplikasi android pada klien yang menggunakan pemodelan UML. Proses pembuatan pada server menggunakan PHP, HTML, CSS, bahasa pemrograman Javascript berdasarkan kerangka CodeIgniter dengan MYSQL sebagai DBMS dan Sublimetext3 sebagai editor, sedangkan klien menggunakan bahasa pemrograman Java dengan Android Studio sebagai IDE. Sebuah sistem panduan mitigasi bencana alam dapat membantu BPBD telah dibuat dapat membantu BPBD dalam mendidik dan meningkatkan layanan kepada masyarakat dalam hal mitigasi bencana terutama di provinsi Sumatera Barat. Kemudian mempermudah masyarakat dalam mengakses informasi tentang mitigasi bencana ala
Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies.
Influenza vaccination programmes are assumed to have a herd effect and protect contacts of vaccinated persons from influenza virus infection. We searched MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Global Health and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to March 2014 for studies assessing the protective effect of influenza vaccination vs no vaccination on influenza virus infections in contacts. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using a random-effects model. Of 43,082 screened articles, nine randomised controlled trials (RCTs) and four observational studies were eligible. Among the RCTs, no statistically significant herd effect on the occurrence of influenza in contacts could be found (OR: 0.62; 95% CI: 0.34-1.12). The one RCT conducted in a community setting, however, showed a significant effect (OR: 0.39; 95% CI: 0.26-0.57), as did the observational studies (OR: 0.57; 95% CI: 0.43-0.77). We found only a few studies that quantified the herd effect of vaccination, all studies except one were conducted in children, and the overall evidence was graded as low. The evidence is too limited to conclude in what setting(s) a herd effect may or may not be achieved
Monitoring settling and consolidation of fluid mud in a laboratory using ultrasonic measurements
Ultrasound measurements are routinely used to evaluate the safe depth for ships navigation - nautical depth - at waterways and ports using single-beam dual-frequency echo-sounders. The nautical depth is routinely defined by suspension density in the range of 1100–1300 kg/m3 in the mud layer. While ultrasound measurements have a weak sensitivity to density variations, calibration is always needed to convert ultrasound measurements into reliable indicators for nautical depth levels in the mud layers using densely distributed density rheological in-situ measurements. We present a laboratory ultrasonic transmission experiment to monitor the fluid mud’s settling and consolidation processes using a sample from the Port of Rotterdam. We use P- and S-wave ultrasonic transducers in the frequency range between 200 to 1000 kHz. Our results show that the P-wave velocities slightly increase during the consolidation and settling process while the P-wave amplitudes decrease. On the other hand, we observe a high S-wave velocity that increases together with amplitudes over time. The P- and S-wave amplitude and S-wave velocity variation over time correlate well with the mud average density variation. The presented results can be very useful for fluid-mud monitoring at a lab scale, besides possible utilization for large-scale monitoring field campaigns
Propane Dehydrogenation Using Transition Metal Cluster Catalysts
Our research seeks to determine the propane dehydrogenation (PDH) reaction pathways using various transition-metal cluster catalysts. We are studying the first step of the reaction, in which a C-H bond is broken. This has been previously shown to be the rate-limiting step of the PDH reaction. We are calculating the PDH activation energy (Ea) using the Vienna Ab-Initio Simulation Package (VASP) in conjunction with the nudged elastic band algorithm. Thus far, we have studied Pt, Ta, and Ni clusters ranging in size from 2-10 atoms. Our goal is to better understand the dependence of Ea on metal type and cluster size
THE CALLOVIAN UNCONFORMITY AND THE OPHIOLITE OBDUCTION ONTO THE PELAGONIAN CARBONATE PLATFORM OF THE INTERNAL HELLENIDES
The carbonate-platform-complex and the oceanic formations of the central Pelagonian zone of the Hellenides evolved in response to a sequence of plate tectonic episodes of ocean spreading, plate convergence and ophiolite obduction. The biostratigraphies of the carbonate platform and the oceanic successions, show that the Triassic-Early Jurassic platform was coeval with an ocean where pillow basalts and radiolarian cherts were being deposited. After convergence began during late Early- Jurassic - Middle Jurassic time, the oceanic leading edge of the Pelagonian plate was subducted beneath the leading edge of the oceanic, overriding plate. The platform subsided while a supra-subduction, volcanic-island-arc evolved. Biostratigraphic and geochemical evidence shows that the platform and the oceanic floor, temporarily became subaerially exposed during Callovian time. This “Callovian event” is suggested to have taken place as oceanic lithosphere first made compressional, tectonic contact with the carbonate platform, initiating a basal detachment fault, along which the platform was thrust upwards. The central Pelagonian zone became an extensive land area that was supplied with laterite from an ophiolite highland. A similar emergence of Vardar ophiolite most likely took place in the Guevgueli area. The Callovian emergence shows that the initial ophiolite obduction onto the platform took place about 25 million years before the final emplacement of the ophiolite during Valanginian time
Using visual data mining in highway traffic safety analysis and decision making
An ongoing, two-fold challenge involves extracting useful information from the massive amounts of highway crash data and explaining complicated statistical models to inform the public about highway safety. Highway safety is critical to the trucking industry and highway funding policy. One method to analyze complex data is through the application of visual data mining tools. In this paper, we address the following three questions: a) what existing data visualization tools can assist with highway safety theory development and in policy-making?; b) can visual data mining uncover unknown relationships to inform the development of theory or practice? and c) can a data visualization toolkit be developed to assist the stakeholders in understanding the impact of publicpolicy on transportation safety? To address these questions, we developed a visual data mining toolkit that allows for understanding safety datasets and evaluating the effectiveness of safety policies
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