A deep learning approach to diabetic blood glucose prediction

We consider the question of 30-minute prediction of blood glucose levels measured by continuous glucose monitoring devices, using clinical data. While most studies of this nature deal with one patient at a time, we take a certain percentage of patients in the data set as training data, and test on the remainder of the patients; i.e., the machine need not re-calibrate on the new patients in the data set. We demonstrate how deep learning can outperform shallow networks in this example. One novelty is to demonstrate how a parsimonious deep representation can be constructed using domain knowledge

Tunable transmission and harmonic generation in nonlinear metamaterials

We study the properties of a tunable nonlinear metamaterial operating at microwave frequencies. We fabricate the nonlinear metamaterial composed of double split-ring resonators and wires where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power. We show that at higher powers the transmission of the metamaterial becomes power dependent, and we demonstrate experimentally power-dependent transmission properties and selective generation of higher harmonics.Comment: 3 page

Precise Measurements of the Kilohertz Quasi-Periodic Oscillations in 4U 1728-34

We have analyzed seventeen observations of the low-mass X-ray binary and atoll source 4U 1728-34, carried out by the Rossi X-ray Timing Explorer in 1996 and 1997. We obtain precise measurements of the frequencies of the two simultaneous kilohertz quasi-periodic oscillations (kHz QPOs) in this source. We show that the frequency separation between the two QPO, $\Delta \nu$, is always significantly smaller than the frequency of the nearly-coherent oscillations seen in this source during X-ray bursts, even at the lowest inferred mass accretion rate, when $\Delta \nu$ seems to reach its maximum value. We also find that $\Delta \nu$ decreases significantly, from $349.3 \pm 1.7$ Hz to $278.7 \pm 11.6$ Hz, as the frequency of the lower frequency kHz QPO increases from 615 to 895 Hz. This is the first time that variations of the kHz QPO peak separation are measured in a source which shows nearly-coherent oscillations during bursts.Comment: Accepted for publication in The Astrophysical Journal Letters. Uses AAS LaTex v4.0 (5 pages plus 4 postscript figures

Ground state correlations and structure of odd spherical nuclei

It is well known that the Pauli principle plays a substantial role at low energies because the phonon operators are not ideal boson operators. Calculating the exact commutators between the quasiparticle and phonon operators one can take into account the Pauli principle corrections. Besides the ground state correlations due to the quasiparticle interaction in the ground state influence the single particle fragmentation as well. In this paper, we generalize the basic QPM equations to account for both mentioned effects. As an illustration of our approach, calculations on the structure of the low-lying states in $^{131}$Ba have been performed.Comment: 12 pages, 1 figur

Effects of different geometries on the conductance, shot noise and tunnel magnetoresistance of double quantum dots

The spin-polarized transport through a coherent strongly coupled double quantum dot (DQD) system is analyzed theoretically in the sequential and cotunneling regimes. Using the real-time diagrammatic technique, we analyze the current, differential conductance, shot noise and tunnel magnetoresistance (TMR) as a function of both the bias and gate voltages for double quantum dots coupled in series, in parallel as well as for T-shaped systems. For DQDs coupled in series, we find a strong dependence of the TMR on the number of electrons occupying the double dot, and super-Poissonian shot noise in the Coulomb blockade regime. In addition, for asymmetric DQDs, we analyze transport in the Pauli spin blockade regime and explain the existence of the leakage current in terms of cotunneling and spin-flip cotunneling-assisted sequential tunneling. For DQDs coupled in parallel, we show that the transport characteristics in the weak coupling regime are qualitatively similar to those of DQDs coupled in series. On the other hand, in the case of T-shaped quantum dots we predict a large super-Poissonian shot noise and TMR enhanced above the Julliere value due to increased occupation of the decoupled quantum dot. We also discuss the possibility of determining the geometry of the double dot from transport characteristics. Furthermore, where possible, we compare our results with existing experimental data on nonmagnetic systems and find qualitative agreement.Comment: 15 pages, 12 figures, accepted in Phys. Rev.

Distribution of averages in a correlated Gaussian medium as a tool for the estimation of the cluster distribution on size

Calculation of the distribution of the average value of a Gaussian random field in a finite domain is carried out for different cases. The results of the calculation demonstrate a strong dependence of the width of the distribution on the spatial correlations of the field. Comparison with the simulation results for the distribution of the size of the cluster indicates that the distribution of an average field could serve as a useful tool for the estimation of the asymptotic behavior of the distribution of the size of the clusters for "deep" clusters where value of the field on each site is much greater than the rms disorder.Comment: 15 pages, 6 figures, RevTe

Spin-polarized transport through weakly coupled double quantum dots in the Coulomb-blockade regime

We analyze cotunneling transport through two quantum dots in series weakly coupled to external ferromagnetic leads. In the Coulomb blockade regime the electric current flows due to third-order tunneling, while the second-order single-barrier processes have indirect impact on the current by changing the occupation probabilities of the double dot system. We predict a zero-bias maximum in the differential conductance, whose magnitude is conditioned by the value of the inter-dot Coulomb interaction. This maximum is present in both magnetic configurations of the system and results from asymmetry in cotunneling through different virtual states. Furthermore, we show that tunnel magnetoresistance exhibits a distinctively different behavior depending on temperature, being rather independent of the value of inter-dot correlation. Moreover, we find negative TMR in some range of the bias voltage.Comment: 9 pages, 7 figures, accepted in Phys. Rev.

Detection and control of individual nuclear spins using a weakly coupled electron spin

We experimentally isolate, characterize and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multi-pulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused by the rest of the spin bath. We are able to address nuclear spins with interaction strengths that are an order of magnitude smaller than the electron spin dephasing rate. Our results provide a route towards tomography with single-nuclear-spin sensitivity and greatly extend the number of available quantum bits for quantum information processing in diamond

Surface acoustic wave modulation of single photon emission from GaN/InGaN nanowire quantum dots

On-chip quantum information processing requires controllable quantum light sources that can be operated on-demand at high-speeds and with the possibility of in-situ control of the photon emission wavelength and its optical polarization properties. Here, we report on the dynamic control of the optical emission from core-shell GaN/InGaN nanowire (NW) heterostructures using radio frequency surface acoustic waves (SAWs). The SAWs are excited on the surface of a piezoelectric lithium niobate crystal equipped with a SAW delay line onto which the NWs were mechanically transferred. Luminescent quantum dot (QD)-like exciton localization centers induced by compositional fluctuations within the InGaN nanoshell were identified using stroboscopic micro-photoluminescence (micro-PL) spectroscopy. They exhibit narrow and almost fully linearly polarized emission lines in the micro-PL spectra and a pronounced anti-bunching signature of single photon emission in the photon correlation experiments. When the nanowire is perturbed by the propagating SAW, the embedded QD is periodically strained and its excitonic transitions are modulated by the acousto-mechanical coupling, giving rise to a spectral fine-tuning within a ~1.5 meV bandwidth at the acoustic frequency of ~330 MHz. This outcome can be further combined with spectral detection filtering for temporal control of the emitted photons. The effect of the SAW piezoelectric field on the QD charge population and on the optical polarization degree is also observed. The advantage of the acousto-optoelectric over other control schemes is that it allows in-situ manipulation of the optical emission properties over a wide frequency range (up to GHz frequencies).Comment: arXiv admin note: text overlap with arXiv:1902.0791

Modelling survival and connectivity of Mnemiopsis leidyi in the south-western North Sea and Scheldt estuaries

Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low-resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming; however, this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here