118 research outputs found

    Integrating Smart Objects into a Integrated Internet of Things Architecture for Smart Cities

    Get PDF
    Increasing population in urban centers day by day demands for more services and infrastructure in order to meet all the needs of residents and visitors of the city. Due to the increased developments in advanced metering and digital technologies smart cities have been equipped with different electronic devices on the basis of Internet of Things (IOT), The utilization of all the technologies to achieve this objective presents an opportunity for the development of smart cities. This paper focus specifically to an urban IOT system and also to provide a comprehensive review on the concepts of smart cities, technologies of IOT and its applications

    Evolución del diseño de interiores en los grandes Centros Comerciales de Lima Central Sur en las últimas tres décadas

    Get PDF
    La investigación responde a una problemática que se evidencia a través de una serie de debilidades que repercuten en el diseño de dichos centros comerciales. El conocimiento de nuevas tecnologías para el diseño interior era escaso, no había conocimientos de enchapes, acabados finos, iluminación decorativa y diseño interior en general. Los materiales tampoco eran de gran ayuda, solo se conocían las estructuras comunes, como el cemento y el acero. Tampoco había conocimientos sobre técnicas constructivas

    Silicon Atomic Quantum Dots Enable Beyond-CMOS Electronics

    Full text link
    We review our recent efforts in building atom-scale quantum-dot cellular automata circuits on a silicon surface. Our building block consists of silicon dangling bond on a H-Si(001) surface, which has been shown to act as a quantum dot. First the fabrication, experimental imaging, and charging character of the dangling bond are discussed. We then show how precise assemblies of such dots can be created to form artificial molecules. Such complex structures can be used as systems with custom optical properties, circuit elements for quantum-dot cellular automata, and quantum computing. Considerations on macro-to-atom connections are discussed.Comment: 28 pages, 19 figure

    Visualizing heterogeneous dipole fields by terahertz light coupling in individual nano-junctions used in transmon qubits

    Full text link
    The fundamental challenge underlying superconducting quantum computing is to characterize heterogeneity and disorder in the underlying quantum circuits. These nonuniform distributions often lead to local electric field concentration, charge scattering, dissipation and ultimately decoherence. It is particularly challenging to probe deep sub-wavelength electric field distribution under electromagnetic wave coupling at individual nano-junctions and correlate them with structural imperfections from interface and boundary, ubiquitous in Josephson junctions (JJ) used in transmon qubits. A major obstacle lies in the fact that conventional microscopy tools are incapable of measuring simultaneous at nanometer and terahertz, "nano-THz" scales, which often associate with frequency-dependent charge scattering in nano-junctions. Here we directly visualize interface nano-dipole near-field distribution of individual Al/AlOx_{x}/Al junctions used in transmon qubits. Our THz nanoscope images show a remarkable asymmetry across the junction in electromagnetic wave-junction coupling response that manifests as "hot" vs "cold" cusp spatial electrical field structures and correlates with defected boundaries from the multi-angle deposition processes in JJ fabrication inside qubit devices. The asymmetric nano-dipole electric field contrast also correlates with distinguishing, "overshoot" frequency dependence that characterizes the charge scattering and dissipation at nanoscale, hidden in responses from topographic, structural imaging and spatially-averaged techniques. The real space mapping of junction dipole fields and THz charge scattering can be extended to guide qubit nano-fabrication for ultimately optimizing qubit coherence times

    Energy-band engineering for improved charge retention in fully self-aligned double floating-gate single-electron memories

    Full text link
    We present a new fully self-aligned single-electron memory with a single pair of nano floating gates, made of different materials (Si and Ge). The energy barrier that prevents stored charge leakage is induced not only by quantum effects but also by the conduction-band offset that arises between Ge and Si. The dimension and position of each floating gate are well defined and controlled. The devices exhibit a long retention time and single-electron injection at room temperature

    Alteration of Proteins and Pigments Influence the Function of Photosystem I under Iron Deficiency from Chlamydomonas reinhardtii

    Get PDF
    BACKGROUND: Iron is an essential micronutrient for all organisms because it is a component of enzyme cofactors that catalyze redox reactions in fundamental metabolic processes. Even though iron is abundant on earth, it is often present in the insoluble ferric [Fe (III)] state, leaving many surface environments Fe-limited. The haploid green alga Chlamydomonas reinhardtii is used as a model organism for studying eukaryotic photosynthesis. This study explores structural and functional changes in PSI-LHCI supercomplexes under Fe deficiency as the eukaryotic photosynthetic apparatus adapts to Fe deficiency. RESULTS: 77K emission spectra and sucrose density gradient data show that PSI and LHCI subunits are affected under iron deficiency conditions. The visible circular dichroism (CD) spectra associated with strongly-coupled chlorophyll dimers increases in intensity. The change in CD signals of pigments originates from the modification of interactions between pigment molecules. Evidence from sucrose gradients and non-denaturing (green) gels indicates that PSI-LHCI levels were reduced after cells were grown for 72 h in Fe-deficient medium. Ultrafast fluorescence spectroscopy suggests that red-shifted pigments in the PSI-LHCI antenna were lost during Fe stress. Further, denaturing gel electrophoresis and immunoblot analysis reveals that levels of the PSI subunits PsaC and PsaD decreased, while PsaE was completely absent after Fe stress. The light harvesting complexes were also susceptible to iron deficiency, with Lhca1 and Lhca9 showing the most dramatic decreases. These changes in the number and composition of PSI-LHCI supercomplexes may be caused by reactive oxygen species, which increase under Fe deficiency conditions. CONCLUSIONS: Fe deficiency induces rapid reduction of the levels of photosynthetic pigments due to a decrease in chlorophyll synthesis. Chlorophyll is important not only as a light-harvesting pigment, but also has a structural role, particularly in the pigment-rich LHCI subunits. The reduced level of chlorophyll molecules inhibits the formation of large PSI-LHCI supercomplexes, further decreasing the photosynthetic efficiency

    SN 2023ixf in Messier 101: Photo-ionization of Dense, Close-in Circumstellar Material in a Nearby Type II Supernova

    Full text link
    We present UV/optical observations and models of supernova (SN) 2023ixf, a type II SN located in Messier 101 at 6.9 Mpc. Early-time ("flash") spectroscopy of SN 2023ixf, obtained primarily at Lick Observatory, reveals emission lines of H I, He I/II, C IV, and N III/IV/V with a narrow core and broad, symmetric wings arising from the photo-ionization of dense, close-in circumstellar material (CSM) located around the progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for ∼\sim8 days with respect to first light, at which time Doppler broadened features from the fastest SN ejecta form, suggesting a reduction in CSM density at r≳1015r \gtrsim 10^{15} cm. The early-time light curve of SN2023ixf shows peak absolute magnitudes (e.g., Mu=−18.6M_{u} = -18.6 mag, Mg=−18.4M_{g} = -18.4 mag) that are ≳2\gtrsim 2 mag brighter than typical type II supernovae, this photometric boost also being consistent with the shock power supplied from CSM interaction. Comparison of SN 2023ixf to a grid of light curve and multi-epoch spectral models from the non-LTE radiative transfer code CMFGEN and the radiation-hydrodynamics code HERACLES suggests dense, solar-metallicity, CSM confined to r=(0.5−1)×1015r = (0.5-1) \times 10^{15} cm and a progenitor mass-loss rate of M˙=10−2\dot{M} = 10^{-2} M⊙_{\odot}yr−1^{-1}. For the assumed progenitor wind velocity of vw=50v_w = 50 km s−1^{-1}, this corresponds to enhanced mass-loss (i.e., ``super-wind'' phase) during the last ∼\sim3-6 years before explosion.Comment: 18 pages, 8 figures. Submitted to ApJ

    Acknowledgement to reviewers of journal of functional biomaterials in 2019

    Get PDF
    • …
    corecore