331 research outputs found
Deterministic creation of stationary entangled states by dissipation
We propose a practical physical system for creation of a stationary
entanglement by dissipation without employing the environment engineering
techniques. The system proposed is composed of two perfectly distinguishable
atoms, through their significantly different transition frequencies, with only
one atom addressed by an external laser field. We show that the arrangement
would easily be realized in practice by trapping the atoms at the distance
equal to the quarter-wavelength of a standing-wave laser field and locating one
of the atoms at a node and the other at the successive antinode of the wave.
The undesirable dipole-dipole interaction between the atoms, that could be
large at this small distance, is adjusted to zero by a specific initial
preparation of the atoms or by a specific polarization of the atomic dipole
moments. Following this arrangement, we show that the dissipative relaxation
can create a stationary entanglement on demand by tuning the Rabi frequency of
the laser field to the difference between the atomic transition frequencies.
The laser field dresses the atom and we identify that the entangled state
occurs when the frequency of one of the Rabi sidebands of the driven atom tunes
to frequency of the undriven atom. It is also found that this system behaves as
a cascade open system where the fluorescence from the dressed atom drives the
other atom with no feedback.Comment: Published versio
Vortex fluidic mediated synthesis of TiO2 nanoparticle/MXene composites
Oxidation of MXene in a vortex fluidic device (VFD) operating under continuous flow results in exfoliation and fragmentation into nanoparticles of surface oxidised 2D material with further oxidation of the nanoparticles into anatase (TiO 2 ). These MXene and anatase nanoparticles coβassemble into stable micron sized spheres which are topologically smooth, decorating the surface of exfoliated MXene. The formation of this composite material in the dynamic thin film in the VFD was optimised by systematically exploring the operating parameters of the microfluidic platform, determined at 45 o tilt angle for the 20 mm diamater glass tube spinning at 5k rpm, with a flow rate of a colloidal dispersion of MXene in aqueous H 2 O 2 (30%) at 0.75 mL/min, concentration of MXene 0.5 mg/mL
Elemental Analysis and Natural Radioactivity Levels of Clay by Gamma Ray Spectrometer and Instrumental Neutron Activation Analysis
Due to increased global demand for clay, the present work involves the use of INAA for elemental analysis and pollutants concentration in clay. The samples were collected from Aswan in South Egypt. The samples were irradiated using the thermal neutrons "at the TRIGA Mainz research reactor" and at a neutron flux "of 7 Γ 10 n/cm s". Twenty-six elements quantitatively and qualitatively were specified for the first time upon studying the samples. The elements determined are U, Th, Ta, Hf, Lu, Eu, Ce, Ba, Sn, Nb, Rb, Zn, Co, Fe, Cr, Sc, Sm, La, Yb, As, Ga, K, Mn, Na, Ti, and Mg. The concentrations of natural radionuclides 232 Th, 226 Ra, and 40 K were also calculated. Based on these concentrations, to estimate the exposure risk for using clay as raw materials in building materials, the radiation hazard indices such as radium equivalent activities, effective doses rate, and the external hazard indices have been computed. The obtained results were compared with analogous studies carried out in other countries and with the UNSCEAR reports
Retrieving and ranking studies for systematic reviews: University of Sheffield's approach to CLEF eHealth 2018 Task 2
This paper describes the University of Sheffield's approach to CLEF 2018 eHealth Task 2: Technologically Assisted Reviews in Empirical Medicine. This task focuses on identifying relevant studies for systematic reviews. The University of Sheffield participated in both subtasks. Our approach to subtask 1 was to extract keywords from search protocols and form them into queries designed to retrieve relevant documents. Our approach to subtask 2 was to enrich queries with terms designed to identify diagnostic test accuracy studies and also by making use of relevance feedback. A total of six official runs were submitted
The USFD Spoken Language Translation System for IWSLT 2014
The University of Sheffield (USFD) participated in the International Workshop for Spoken Language Translation (IWSLT) in 2014. In this paper, we will introduce the USFD SLT system for IWSLT. Automatic speech recognition (ASR) is achieved by two multi-pass deep neural network systems with adaptation and rescoring techniques. Machine translation (MT) is achieved by a phrase-based system. The USFD primary system incorporates state-of-the-art ASR and MT techniques and gives a BLEU score of 23.45 and 14.75 on the English-to-French and English-to-German speech-to-text translation task with the IWSLT 2014 data. The USFD contrastive systems explore the integration of ASR and MT by using a quality estimation system to rescore the ASR outputs, optimising towards better translation. This gives a further 0.54 and 0.26 BLEU improvement respectively on the IWSLT 2012 and 2014 evaluation data
Three-dimensional printing of porous load-bearing bioceramic scaffolds
This article reports on the use of the binder jetting three-dimensional printing process combined with sintering to process bioceramic materials to form micro- and macroporous three-dimensional structures. Three different glass-ceramic formulations, apatiteβwollastonite and two silicate-based glasses, have been processed using this route to create porous structures which have Youngβs modulus equivalent to cortical bone and average bending strengths in the range 24β36 MPa. It is demonstrated that a range of macroporous geometries can be created with accuracies of Β±0.25 mm over length scales up to 40 mm. Hot-stage microscopy is a valuable tool in the definition of processing parameters for the sintering step of the process. Overall, it is concluded that binder jetting followed by sintering offers a versatile process for the manufacture of load-bearing bioceramic components for bone replacement applications
Mutual Relationships: Saudi Universities and The Private Sector for Economic Development
The purpose of this research is to determine the level of the mutual relationship between Saudi universities and the private sector to achieve Economic development in light of the Kingdoms 2030 vision. The researcher relied heavily on the questionnaire as the primary instrument for data collection for the study, employing a descriptive research design and a quantitative methodology in order to accomplish the goals of the study. The investigation was carried out with a sample size of 180 universities leaders in the southern region of Saudi Arabia, all of them were chosen at random. The findings of this study indicated that leaders had high expectations for a mutual relationship between Saudi universities and the private sector. In addition, the findings demonstrated that there are no statistically significant variations in the mutual relationship between Saudi universities and the private sector with regard to the variables of academic rank, and years of experience
Molecular identification of adenoviruses associated with respiratory infection in Egypt from 2003 to 2010.
BACKGROUND: Human adenoviruses of species B, C, and E (HAdV-B, -C, -E) are frequent causative agents of acute respiratory infections worldwide. As part of a surveillance program aimed at identifying the etiology of influenza-like illness (ILI) in Egypt, we characterized 105 adenovirus isolates from clinical samples collected between 2003 and 2010. METHODS: Identification of the isolates as HAdV was accomplished by an immunofluorescence assay (IFA) and confirmed by a set of species and type specific polymerase chain reactions (PCR). RESULTS: Of the 105 isolates, 42% were identified as belonging to HAdV-B, 60% as HAdV-C, and 1% as HAdV-E. We identified a total of six co-infections by PCR, of which five were HAdV-B/HAdV-C co-infections, and one was a co-infection of two HAdV-C types: HAdV-5/HAdV-6. Molecular typing by PCR enabled the identification of eight genotypes of human adenoviruses; HAdV-3 (nβ=β22), HAdV-7 (nβ=β14), HAdV-11 (nβ=β8), HAdV-1 (nβ=β22), HAdV-2 (20), HAdV-5 (nβ=β15), HAdV-6 (nβ=β3) and HAdV-4 (nβ=β1). The most abundant species in the characterized collection of isolates was HAdV-C, which is concordant with existing data for worldwide epidemiology of HAdV respiratory infections. CONCLUSIONS: We identified three species, HAdV-B, -C and -E, among patients with ILI over the course of 7 years in Egypt, with at least eight diverse types circulating
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