Search

One of the major challenges to the widespread adoption of plasmonic and nano-optical devices in real-life applications is the difficulty to mass-fabricate nano-optical antennas in parallel and reproducible fashion, and the capability to precisely place nanoantennas into devices with nanometer-scale precision. In this study, we present a solution to this challenge using the state-of-the-art ultraviolet nanoimprint lithography (UV-NIL) to fabricate functional optical transformers onto the core of an optical fiber in a single step, mimicking the 'campanile' near-field probes. Imprinted probes were fabricated using a custom-built imprinter tool with co-axial alignment capability with sub

Fano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering (SERS). Despite such interest in nano-optics, no experimental evidence of Fano interference was reported up to now for purely nanomechanical resonators, even if classical mechanical analogies were referred from a theoretical point of view. Here we demonstrate for the first time that harmonic nanomechanical resonators with relatively high quality factors, such as cantilevers vibrating in vacuum, can show characteristic Fano asymmetric curves when coupled in arrays. The reported findings open new perspectives in fundamental aspects of classical nanomechanical resonators and pave the way to a new generation of chemical and biological nanoresonator sensors with higher parallelization capability.

The semiconductor industry is moving toward a half-pitch of 7 nm. The required metrology equipment should be one order of magnitude more accurate than that. Any metrology tool is only as good as it is calibrated. The characterization of metrology systems requires test patterns that are one order of magnitude smaller than the measured features. The test sample was designed in such a way that the distribution of linewidths appears to be random at any location and any magnification. The power spectral density of such pseudo-random test pattern is inherently flat, down to the minimum size of lines. Metrology systems add a cut-off of the spectra at high frequencies; the shape of the cut-off characterizes the system in its entire dynamic range. This method is widely used in optics, and has allowed optical systems to be perfected down to their diffraction limit. There were attempts to use the spectral method to characterize nanometrology systems such as SEMs, but the absence of natural samples with known spatial frequencies was a common problem. Pseudo-random test patterns with linewidths down to 1.5 nm were fabricated. The system characterization includes the imaging of a pseudo-random test sample and image analysis by a developed software to automatically extract the power spectral density and the contrast transfer function of the nanoimaging system.

We present a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) one-dimensional sequences and two-dimensional arrays as an effective method for spectral characterization in the spatial frequency domain of a broad variety of metrology instrumentation, including interferometric microscopes, scatterometers, phase shifting Fizeau interferometers, scanning and transmission electron microscopes, and at this time, x-ray microscopes. The inherent power spectral density of BPR gratings and arrays, which has a deterministic white-noise-like character, allows a direct determination of the MTF with a uniform sensitivity over the entire spatial frequency range and field of view of an instrument. We demonstrate the MTF calibration and resolution characterization over the full field of a transmission soft x-ray microscope using a BPR multilayer (ML) test sample with 2.8 nm fundamental layer thickness. We show that beyond providing a direct measurement of the microscope's MTF, tests with the BPRML sample can be used to fine tune the instrument's focal distance. Our results confirm the universality of the method that makes it applicable to a large variety of metrology instrumentation with spatial wavelength bandwidths from a few nanometers to hundreds of millimeters.

Any metrology tool is only as good as it is calibrated. The characterization of metrology systems requires test patterns at a scale about ten times smaller than the measured features. The fabrication of patterns with linewidths down to 1.5 nm is described. The test sample was designed in such a way that the distribution of linewidths appears to be random at any location. This pseudorandom test pattern is used to characterize dimensional metrology equipment over its entire dynamic range by extracting the modulation transfer function of the system. The test pattern contains alternating lines of silicon and tungsten silicide, each according to its designed width. The fabricated test samples were imaged using a transmission electron microscope, a scanning electron microscope, and an atomic force microscope.

This work reports on the development of a binary pseudo-random test sample optimized to calibrate the MTF of optical microscopes. The sample consists of a number of 1-D and 2-D patterns, with different minimum sizes of spatial artifacts from 300 nm to 2 microns. We describe the mathematical background, fabrication process, data acquisition and analysis procedure to return spatial frequency based instrument calibration. We show that the developed samples satisfy the characteristics of a test standard: functionality, ease of specification and fabrication, reproducibility, and low sensitivity to manufacturing error.

A major road-block in stem cell therapy is the poor homing and integration of transplanted stem cells with the targeted host tissue. Human induced pluripotent stem (hiPS) cells are considered an excellent alternative to embryonic stem (ES) cells and we tested the feasibility of using small, physiological electric fields (EFs) to guide hiPS cells to their target. Applied EFs stimulated and guided migration of cultured hiPS cells toward the anode, with a stimulation threshold of

In this note we discuss the system optimum dynamic traffic assignment (SO-DTA) problem in the presence of time-dependent uncertainty on the demands and link capacities. We start from the deterministic linear programming formulation of the SO-DTA problem introduced by Ziliaskopoulos in [14], and then consider a robust version of the decision problem where the total travel time must be minimized under a worst-case scenario of demand and capacity configurations. When uncertain demands and capacities are modeled as unknown-but-bounded quantities restricted in intervals, the resulting robust decision problem can still be formulated as a linear program and solved at the same computational cost as its nominal counterpart. Worst-case solutions to assignment problems appear to be useful for establishing routing policies that are resilient to possibly large variations of network parameters and for computing lower bounds on network performance in extreme situations.

This article is a systematic review that examines the role of vitamin D in orthodontic tooth movement, external apical root resorption, and bone biomarker expression and remodeling. The review analyzed 19 studies that investigated the correlation between vitamin D levels and various factors related to orthodontic treatment. The findings suggest that local injections of vitamin D may increase the rate of tooth movement, but the varying study designs and protocols make it difficult to draw definitive conclusions. Further research is needed to fully understand the impact of vitamin D on orthodontic treatment. [Extracted from the article]

The notion that development influences children's responses to traumatic stress is not novel. Chronological age and maturity level interact with environmental factors to mediate responses to trauma. Clinicians and researchers have confirmed that children can experience the full range of traumatic stress reactions seen in adults, and many youth meet criteria for DSM-IV diagnoses of either acute stress disorder or posttraumatic stress disorder (PTSD). However, many types of childhood trauma including psychological maltreatment, neglect, separation from caregivers, and inappropriate sexual contact are not fully accounted for by these disorders. Even when children experience events that are more commonly characterized as traumas, research indicates that their reactions are not fully congruent with the criteria provided in the DSM-IV, suggesting that these criteria may not adequately describe trauma responses in the pediatric population. Services and treatment for trauma are often conceptualized as interventions after the fact, rather than proactive measures. While reactive interventions are clearly valuable, there are multiple opportunities for school psychologists to implement prevention-based practices that will address the needs of young children who have experienced trauma. In this article, the author discusses how to understand and address early childhood trauma.

This article studies the determinants of academic achievement in online courses in economics and finance. The authors use the online tracking feature in Blackboard (Campus Edition) to retrieve the real time that each student spent in the course for the entire semester and to analyze the impact of time spent online, prior grade point average (GPA), and some demographic characteristics of students on their final grades. Both time and GPA are significant determinants of the final grade: Higher GPAs and longer times spent online are associated with higher grades. (Contains 9 tables and 7 notes.)

Many real-world dynamical systems are characterized by different temporal phases, with sudden changes in the values of the system's parameters in correspondence to variations from one phase to another. Identifying the system's parameters and these switching instants from potentially noisy measurements of the system's states is a relevant problem in several applications. We here propose a novel approach for estimating the time-varying parameters of a broad class of nonlinear dynamical systems from noisy state measurements. We formulate the problem as a mixed-integer quadratic program (MIQP) including a sparsity constraint to enforce the piecewise constant nature of the parameters. Then, we develop a convex relaxation of the problem in the form of a quadratic program (QP). The solution of the relaxed convex QP and/or the sub-optimal solutions of the MIQP returned by the MIQP solvers provide us with computationally-efficient approximations that can be used effectively in those large-dimensional cases in which the solution of the original MIQP is difficult to obtain. After validating our approach in a controlled experiment, we demonstrate its potential on two real-world case studies regarding marketing and epidemiological applications. [ABSTRACT FROM AUTHOR]

Introduction: The treatment of type 2 diabetes mellitus (T2DM) is based on preventive hygiene and dietary measures (HDM), oral antidiabetic drugs (OADs), and insulin. The objective of the present study was to reuse general practice data from electronic health records and describe changes over time among patients with T2DM in primary care.Methods: We analyzed data on patients with T2DM collected by three family physicians in Tourcoing (France) from 2006 to 2018.Results: 403 patients, 1030 treatment sequences, 39,042 appointments, 2440 glycated hemoglobin (HbA1c) measurements, and 9722 wt measurements were included. On inclusion, the mean age was 57.0, the mean weight was 84.4 kg, the mean body mass index was 30.3 kg/m2, and the median HbA1c level was 6.8 % (51 mmol/mol). The patients were following appropriate HDM (40.7 %) and/or were being treated with OADs (54.1 %) or insulin (5.2 %). The median length of follow-up was 3.51 years. Overall, bodyweight was stable for two years during HDM and then increased. The HbA1c level decreased and then increased during HDM, was stable on OADs, and then decreased on insulin.Discussion/conclusion: The present descriptive results may be of value in helping to predict changes over time in bodyweight and HbA1c in T2DM. [ABSTRACT FROM AUTHOR]