Minimal model of point contact Andreev reflection spectroscopy of multiband superconductors

We formulate a minimal model of point contact Andreev reflection spectroscopy of a normal- metal/multiband superconductor interface. The theory generalizes the Blonder-Tinkham-Klapwijk (BTK) formulation to a multiband superconductor and it is based on the quantum waveguides theory. The proposed approach allows an analytic evaluation of the Andreev and normal reflection coefficients and thus is suitable for a data fitting of point contact experiments. The obtained differential conductance curves present distinctive features similar to the ones measured in the experiments on multiband systems, like the iron-based pnictides and the MgB2.Comment: 5 pages, 4 figure

Electrically Controlled Pumping of Spin Currents in Topological Insulators

Pure spin currents are shown to be generated by an electrically controlled quantum pump applied at the edges of a topological insulator. The electric rather than the more conventional magnetic control offers several advantages and avoids, in particular, the necessity of delicate control of magnetization dynamics over tiny regions. The pump is implemented by pinching the sample at two quantum point contacts and phase modulating two external gate voltages between them. The spin current is generated for the full range of parameters. On the other hand, pumping via amplitude modulation of the inter-boundary couplings generates both charge and spin currents, with a pure charge current appearing only for special values of the parameters for which the Bohm-Aharonov flux takes integer values. Our setup can therefore serve to fingerprint the helical nature of the edges states with the zeros of the pumped spin and charge currents occurring at distinct universal locations where the Fabry-Perot or the Aharonov-Bohm phases take integer values.Comment: 5 pages, 5figure

Time Evolution of Non-Lethal Infectious Diseases: A Semi-Continuous Approach

A model describing the dynamics related to the spreading of non-lethal infectious diseases in a fixed-size population is proposed. The model consists of a non-linear delay-differential equation describing the time evolution of the increment in the number of infectious individuals and depends upon a limited number of parameters. Predictions are in good qualitative agreement with data on influenza.Comment: 21 page

Impurity effects on Fabry-Perot physics of ballistic carbon nanotubes

We present a theoretical model accounting for the anomalous Fabry-Perot pattern observed in the ballistic conductance of a single-wall carbon nanotubes. Using the scattering field theory, it is shown that the presence of a limited number of impurities along the nanotube can be identified by a measurement of the conductance and their position determined. Impurities can be made active or silent depending on the interaction with the substrate via the back-gate. The conceptual steps for designing a bio-molecules detector are briefly discussed.Comment: 4 pages, 4 figure

Spin-torque generation by dc or ac voltages in magnetic layered structures

A general expression of the current induced spin torque in a magnetic layered structure in the presence of external dc or ac voltages is derived in the framework of the scattering matrix approach. A detailed analysis is performed for a magnetic-nonmagnetic-magnetic trilayer connected to external leads in the presence of dc voltage bias in the ballistic regime. Alternatively, the possibility of producing spin torque by means of the adiabatic ac modulation of external gate voltages (quantum pumping) is proposed and discussed

Filmless Hospital with PACS as a Workflow Controller, Case Study: National Hospital Surabaya

Traditionally radiology produces a visual representation of medical images in film format for further clinical analysis. While some healthcare providers still used films to display scan results, others are embracing the advancing technology of digital medical images. In radiology, this medical imaging technique is generally equated to filmless radiology. However, modern technology has enabled other clinical areas beyond radiology to use digital imaging, including cardiology, pathology, obstetric and gynecology, orthopedic and dentistry. This widely implementation of filmless system in hospital is known as filmless hospital. This paper discusses filmless hospital using picture archiving and communication system (PACS) as workflow controller as a case study at National Hospital Surabaya

Quantum pumping in deformable quantum dots

The charge current pumped adiabatically through a deformable quantum dot is studied within the Green's function approach. Differently from the non-deformable case, the current shows an undefined parity with respect to the pumping phase \phi. The unconventional current-phase relation, analyzed in the weak pumping regime, is due to a dynamical phase shift \phi_D caused by the elastic deformations of the central region (classical phonons). The role of the quality factor Q of the oscillator, the effects induced by a mechanical resonance and the implications for current experiments on molecular systems are also discussed