An Entourage Approach to the Contraction Principle in Uniform Spaces Endowed with a Graph

In this paper, we study Banach contractions in uniform spaces endowed with a graph and give some sufficient conditions for a mapping to be a Picard operator. Our main results generalize some results of [J. Jachymski, "The contraction principle for mappings on a metric space with a graph", Proc. Amer. Math. Soc. 136 (2008) 1359-1373] employing the basic entourages of the uniform space.Comment: 20 page

Quantum-dot-spin single-photon interface

Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0:1%, we realize a single spin-photon interface where the detection of a scattered photon with 300 picosecond time resolution projects the quantum dot spin to a definite spin eigenstate with fidelity exceeding 99%. The bunching of resonantly scattered photons reveals information about electron spin dynamics. High-fidelity fast spin-state initialization heralded by a single photon enables the realization of quantum information processing tasks such as non-deterministic distant spin entanglement. Given that we could suppress the measurement back-action to well below the natural spin-flip rate, realization of a quantum non-demolition measurement of a single spin could be achieved by increasing the fluorescence collection efficiency by a factor exceeding 20 using a photonic nanostructure

Quantum Teleportation from a Propagating Photon to a Solid-State Spin Qubit

The realization of a quantum interface between a propagating photon used for transmission of quantum information, and a stationary qubit used for storage and manipulation, has long been an outstanding goal in quantum information science. A method for implementing such an interface between dissimilar qubits is quantum teleportation, which has attracted considerable interest not only as a versatile quantum-state-transfer method but also as a quantum computational primitive. Here, we experimentally demonstrate transfer of quantum information carried by a photonic qubit to a quantum dot spin qubit using quantum teleportation. In our experiment, a single photon in a superposition state of two colors -- a photonic qubit is generated using selective resonant excitation of a neutral quantum dot. We achieve an unprecedented degree of indistinguishability of single photons from different quantum dots by using local electric and magnetic field control. To teleport a photonic qubit, we generate an entangled spin-photon state in a second quantum dot located 5 meters away from the first and interfere the photons from the two dots in a Hong-Ou-Mandel set-up. A coincidence detection at the output of the interferometer heralds successful teleportation, which we verify by measuring the resulting spin state after its coherence time is prolonged by an optical spin-echo pulse sequence. The demonstration of successful inter-conversion of photonic and semiconductor spin qubits constitute a major step towards the realization of on-chip quantum networks based on semiconductor nano-structures.Comment: 12 pages, 3 figures, Comments welcom

Hybrid Quantum Dot-2D Electron Gas Devices for Coherent Optoelectronics

We present an inverted GaAs 2D electron gas with self-assembled InAs quantum dots in close proximity, with the goal of combining quantum transport with quantum optics experiments. We have grown and characterized several wafers -- using transport, AFM and optics -- finding narrow-linewidth optical dots and high-mobility, single subband 2D gases. Despite being buried 500 nm below the surface, the dots are clearly visible on AFM scans, allowing precise localization and paving the way towards a hybrid quantum system integrating optical dots with surface gate-defined nanostructures in the 2D gas.Comment: 4 pages, 5 figures (color

The effect of heavy metal on Chlorella vulgaris, Scenedesmus obliquus and Anabaena flos-aquae

In this survey two species of chlorophyta (Chlorella vulgaris and Scenedesmus obliquus) and one species of blue-green algae (Anabaena flos- aquae) were exposed with heavy metal (zinc) under lab condition (temp. 25±2°C, light 3500±350 lux) for 96 hours. After this time, these species were counted with hemocytometer and based on probit analysis method and was determined ECIO, EC50 and EC90. Amount of EC50 for C. vulgaris, S. obliquus and A. flos-aquae were 0.134,0.047 and 0.093 mg/lit, respectively and this subject was distincted that S obliquus has more endurance than other species. Max value of zinc for these species (C. vulgaris, S. obiquus and A. flos-aquae ) were 0.0134, 0.0047 and 0.0093 mg/l respectively. Regression coefficient was 92-98 percent between concentration logarithm of zinc and decrease of these species density

Internet Addiction and its Predictors in Guilan Medical Sciences Students, 2012

Background: Internet is one of the technologies of the modern era that is being extensively used around the world. It is believed that excessive Internet use can be pathological and addictive. Though, academic use of the Internet is primarily intended for learning and research, students are one of the groups at risk of Internet addiction. Objectives: Due to the expanding use of Internet among the university students, this study was conducted to examine the Internet addiction and its predictors among Guilan University of Medical Sciences students. Materials and Methods: A cross-sectional study was conducted on 583 students during the first semester of 2012. A two-stage stratified random sampling was conducted and a two-part instrument was used for data collection. The first part of the instrument was consisted of questions about demographic characteristics and the second part was the Young's Internet addiction inventory. Chi-square, Kruskal-Wallis testes, Spearman correlation coefficient and ranked logistic regression were used for data analysis. Results: About 5.7% of the students were moderately dependent to the Internet, while 44.1% were at risk for Internet addiction. Significant relationships were observed between the Internet addiction with age (P < 0.001), gender (P < 0.001), marital status (P < 0.001), major (P = 0.016), Grade point average (P = 0.017), semester of studying (P = 0.009) and student residence place (P = 0.014). However, no significant relationship was observed between the internet addiction score and level of discipline, parental job status and education level or the students’ accommodation. Conclusion: About half of the participants in this study were at risk of Internet addiction. This finding can be a warning sign for the authorities in universities to pay more attention to this issue. A wide range of education along with empowering programs may be needed to inform the university students about the advantages and disadvantages of internet and the correct manner of using it

Pattern recognition of acoustic emission signal during the mode I fracture mechanisms in carbon- epoxy composite

The aim of the paper is to use Acoustic Emission technique to distinguish the micro/macro failure mechanisms of carbon-epoxy composite laminates during Double Cantilever Beam (DCB) tests. In order to recognize and detect different damage mechanisms, Self-Organizing Map (SOM) method has been used to cluster the AE signals according with the fracture mode that originated them. In addition, most significate Learning vector quantization (LVQ) program has been applied to verify the signals. Five AE features were selected as main parameters: Rise-time, Counts, Energy, Duration and Amplitude. The results highlighted that different signals can be recognized and classified related to their origin. The failure mechanisms detected are Matrix cracking, delamination, and fiber breakage. Scanning Electron Microscopy (SEM) images validate the results. Mathematics data and experimental results confirmed a good converging of AE dat