Single-poly floating-gate memory cell options for analog neural networks

In this paper, we explore the use of a 180 nm CMOS single-poly technology platform for realizing analog Deep Neural Network integrated circuits. The analysis focuses on analog vector–matrix multiplier architectures, one of the main building blocks of a neural network, implementing in-memory computation using Floating-Gate multi-level non-volatile memories. We present two memory options, suited either for current-mode or for time-domain vector–matrix multiplier implementations, with low–voltage charge-injection program and erase operations. The effects of a limited accuracy are also investigated through system-level simulations, by accounting for the temperature dependence of the stored weights and the corresponding impact on the network error rate

Three Dimensional Visualization and Fractal Analysis of Mosaic Patches in Rat Chimeras: Cell Assortment in Liver, Adrenal Cortex and Cornea

The production of organ parenchyma in a rapid and reproducible manner is critical to normal development. In chimeras produced by the combination of genetically distinguishable tissues, mosaic patterns of cells derived from the combined genotypes can be visualized. These patterns comprise patches of contiguously similar genotypes and are different in different organs but similar in a given organ from individual to individual. Thus, the processes that produce the patterns are regulated and conserved. We have previously established that mosaic patches in multiple tissues are fractal, consistent with an iterative, recursive growth model with simple stereotypical division rules. Fractal dimensions of various tissues are consistent with algorithmic models in which changing a single variable (e.g. daughter cell placement after division) switches the mosaic pattern from islands to stripes of cells. Here we show that the spiral pattern previously observed in mouse cornea can also be visualized in rat chimeras. While it is generally held that the pattern is induced by stem cell division dynamics, there is an unexplained discrepancy in the speed of cellular migration and the emergence of the pattern. We demonstrate in chimeric rat corneas both island and striped patterns exist depending on the age of the animal. The patches that comprise the pattern are fractal, and the fractal dimension changes with the age of the animal and indicates the constraint in patch complexity as the spiral pattern emerges. The spiral patterns are consistent with a loxodrome. Such data are likely to be relevant to growth and cell division in organ systems and will help in understanding how organ parenchyma are generated and maintained from multipotent stem cell populations located in specific topographical locations within the organ. Ultimately, understanding algorithmic growth is likely to be essential in achieving organ regeneration in vivo or in vitro from stem cell populations

Low Frequency Quantum Transport in a Three-probe Mesoscopic Conductor

The low frequency quantum transport properties of a three-probe mesoscopic conductor are studied using B\"uttiker's AC transport formalism. The static transmission coefficients and emittance matrix of the system were computed by explicitly evaluating the various partial density of states (PDOS). We have investigated the finite size effect of the scattering volume on the global PDOS. By increasing the scattering volume we observed a gradual improvement in the agreement of the total DOS as computed externally or locally. Our numerical data permits a particular fitting form of the finite size effect.Comment: 13 pages, LaTeX, submitted to Phys. Rev.

CUMAS: a seafloor multi-sensor module for volcanic hazard monitoring - First long-term experiment and performance assessment

A seafloor multi-sensor module with real-time data transmission, named CUMAS (Cabled Underwater Module for Acquisition of Seismological data), has been deployed in January 2008 in the Gulf of Pozzuoli, in the Campi Flegrei caldera (southern Italy), which is one of the most active volcanic areas in the world. The sensors installed in CUMAS were selected to monitor a set of signals related to the local seismicity as well as the ground uplift and subsidence of the seafloor that are related to the bradyseismic phenomenon. In particular, together with a broad-band three-component seismometer and a low-frequency hydrophone, a seafloor water-pressure sensor is used to assess the feasibility of measurements of the slow vertical movement of the seafloor (bradyseism). Further sensors are acquired by two embedded Linux computers, namely tilt and heading sensors for the measure of the actual module orientation on the seafloor, and status sensors that monitor the state of health of the vessel (e.g., internal temperature, power absorption, water intrusion). The underwater acquisition systems are linked to a support infrastructure, a floating buoy (elastic beacon), through an electro-mechanical cable with an Ethernet line. The buoy provides the needed power supply thanks to batteries charged by solar panels and a wind- generator. A Wi-Fi antenna on the buoy is used to transmit the seafloor data from the sea surface to the land acquisition centre in the city of Naples. A meteorological station is also mounted on the buoy, to allow the correlation of the air and seafloor data. CUMAS, although based on commercial sensors, relies on an original system for the centralized management of a wide set of geophysical and physical oceanographic sensors, that handles the continuous data acquisition and real-time data transmission. After the installation in the Gulf of Pozzuoli at about 100 m w.d., and after a test period, CUMAS uninterruptedly operated from May 2008 to June 2009, thus providing continuous geophysical data to the Monitoring Center of the Campi Flegrei volcanic areas, managed by the Istituto Nazionale di Geofisica e Vulcanologia. The long-term operational performance of CUMAS is presented here, together with the first results from the analysis of the geophysical long time-series acquired. Examples of the acquired signals, especially geophysical data, will be presented to point out the high quality in term of signal-to-noise ratio. In particular, earthquake recordings obtained from the hydrophone resulted of comparable quality to the seismic data acquired on land by the permanent network, thus demonstrating the suitability of hydrophones to monitor the seismic activity of the caldera

Nonlinear voltage dependence of shot noise

The current noise in a multi-probe mesoscopic conductor can have a nonlinear dependence on the strength of driving bias voltage. This paper presents a theoretical formulation for the nonlinear noise spectra. We pay special attention to maintain gauge invariance at the nonlinear level. At small but finite voltages, explicit expressions for nonlinear noise spectra, expanded order by order in the bias, have been derived. In the wideband limit, a closed form solution of the noise spectra for finite voltages is obtained

Two-dimensional hole precession in an all-semiconductor spin field effect transistor

We present a theoretical study of a spin field-effect transistor realized in a quantum well formed in a p--doped ferromagnetic-semiconductor- nonmagnetic-semiconductor-ferromagnetic-semiconductor hybrid structure. Based on an envelope-function approach for the hole bands in the various regions of the transistor, we derive the complete theory of coherent transport through the device, which includes both heavy- and light-hole subbands, proper modeling of the mode matching at interfaces, integration over injection angles, Rashba spin precession, interference effects due to multiple reflections, and gate-voltage dependences. Numerical results for the device current as a function of externally tunable parameters are in excellent agreement with approximate analytical formulae.Comment: 9 pages, 11 figure

Partial Densities of States, Scattering Matrices, and Green's Functions

The response of an arbitrary scattering problem to quasi-static perturbations in the scattering potential is naturally expressed in terms of a set of local partial densities of states and a set of sensitivities each associated with one element of the scattering matrix. We define the local partial densities of states and the sensitivities in terms of functional derivatives of the scattering matrix and discuss their relation to the Green's function. Certain combinations of the local partial densities of states represent the injectivity of a scattering channel into the system and the emissivity into a scattering channel. It is shown that the injectivities and emissivities are simply related to the absolute square of the scattering wave-function. We discuss also the connection of the partial densities of states and the sensitivities to characteristic times. We apply these concepts to a delta-barrier and to the local Larmor clock.Comment: 13 pages (revtex), 4 figure

Restoration of Nusinersen Levels Following Treatment Interruption in People With Spinal Muscular Atrophy: Simulations Based on a Population Pharmacokinetic Model

Background: Nusinersen is approved for the treatment of spinal muscular atrophy. The most common approved dosing regimen is four intrathecal loading doses of nusinersen 12 mg; the first three are administered at 14-day intervals followed by a fourth dose 30 days later, and then 12-mg maintenance doses are administered every 4 months thereafter. Interruption of nusinersen treatment in the maintenance dosing phase might occur for a number of clinical reasons. / Objective: The objective of this report is to describe dosing regimens that allow for the most rapid restoration of steady-state concentrations of nusinersen in the cerebrospinal fluid (CSF) following a treatment interruption during maintenance dosing. / Methods: Population pharmacokinetic models using integrated pharmacokinetic data from ten nusinersen clinical trials that included a broad range of participants with spinal muscular atrophy treated with intrathecal nusinersen were used to investigate different durations of treatment interruptions during maintenance treatment. Potential dosing regimens for re-initiation of nusinersen were evaluated, with the goal of achieving the quickest restoration of steady-state nusinersen CSF concentrations without exceeding maximal CSF exposures observed during the initial loading period. / Results: Our pharmacokinetic modeling indicates the following regimen will lead to optimal restoration of nusinersen CSF levels after treatment interruption: two doses of nusinersen should be administered at 14-day intervals following treatment interruptions of ≥ 8 to < 16 months since the last dose, and three doses of nusinersen at 14-day intervals for treatment interruptions of ≥ 16 to < 40 months since the last maintenance dose, with subsequent maintenance dosing every 4 months in both instances. After treatment interruptions of ≥ 40 months, the full loading regimen will rapidly restore nusinersen CSF levels. / Conclusions: Prolonged treatment interruptions lead to suboptimal CSF levels of nusinersen. The optimal regimen to restore nusinersen CSF levels depends on the interval since the last maintenance dose was administered

Low-voltage 2D materials-based printed field-effect transistors for integrated digital and analog electronics on paper

Paper is the ideal substrate for the development of flexible and environmentally sustainable ubiquitous electronic systems, which, combined with two-dimensional materials, could be exploited in many Internet-of-Things applications, ranging from wearable electronics to smart packaging. Here we report high-performance MoS2 field-effect transistors on paper fabricated with a “channel array” approach, combining the advantages of two large-area techniques: chemical vapor deposition and inkjet-printing. The first allows the pre-deposition of a pattern of MoS2; the second, the printing of dielectric layers, contacts, and connections to complete transistors and circuits fabrication. Average ION/IOFF of 8 × 103 (up to 5 × 104) and mobility of 5.5 cm2 V−1 s−1 (up to 26 cm2 V−1 s−1) are obtained. Fully functional integrated circuits of digital and analog building blocks, such as logic gates and current mirrors, are demonstrated, highlighting the potential of this approach for ubiquitous electronics on paper

Current conservation in two-dimensional AC-transport

The electric current conservation in a two-dimensional quantum wire under a time dependent field is investigated. Such a conservation is obtained as the global density of states contribution to the emittance is balanced by the contribution due to the internal charge response inside the sample. However when the global partial density of states is approximately calculated using scattering matrix only, correction terms are needed to obtain precise current conservation. We have derived these corrections analytically using a specific two-dimensional system. We found that when the incident energy $E$ is near the first subband, our result reduces to the one-dimensional result. As $E$ approaches to the $n$-th subband with $n>1$, the correction term diverges. This explains the systematic deviation to precise current conservation observed in a previous numerical calculation.Comment: 12 pages Latex, submitted to Phys. Rev.