Synthetic Instrument Research Articles

Synthetic instruments in DiD designs with unmeasured confounding

Synthetic instruments in DiD designs with unmeasured confounding

A Spatial Econometric Analysis of Productivity Variations Across US Cities

Using a dynamic spatial panel model applied to 377 US Metropolitan Statistical Areas (MSAs), estimated over the period 2011-2021, significant differences are found between large MSAs regarding the relationship between labour productivity and economic mass, as measured by GDP. The methodology adopted illustrates the state of the art for spatial econometric modeling as it is often needed in practice, allowing for multiple endogenous regressors and dynamic effects. The estimation method applies synthetic instruments designed to limit negative effects of instrument overabundance.

Laboratory Characterisation of a Commercial RGB CMOS Camera for Measuring Night Sky Brightness

The use of RGB cameras in photometric applications has grown over the last few decades in many fields such as industrial applications, light engineering and the analysis of the quality of the night sky. In this last field, they are often used in conjunction with a Sky Quality Meter (SQM), an instrument used for the measurement of night sky brightness (NSB), mainly when there is a significant amount of artificial light at night (ALAN). The performances of these two instruments are compared here. A simple source composed of nine narrowband LEDs in an integrating sphere was used to excite the two instruments and therefore measure the spectral responsivity of the SQM and of the three channels of the camera. The estimated uncertainties regarding spectral responsivity were less than 10%. A synthetic instrument approximating the SQM’s responsivity can be created using a combination of the R, G and B channels. The outputs of the two instruments were compared by measuring the spectral radiance of the night sky. An evaluation of the spectral mismatch between the two instruments completed the analysis of their spectral sensitivity. Finally, the measurements of real SQMs in four sites experiencing different levels of light pollution were compared with the values obtained by processing the recorded RGB images. Overall, the analysis shows that the two instruments have significantly different levels of spectral responsivity, and the alignment of their outputs requires the use of a correction which depends on the spectral distribution of the light coming from the sky. A synthetic SQM will always underestimate real SQM measures; an average correction factor was evaluated considering nine sky spectra under low and medium levels of light pollution; this was determined to be 1.11 and, on average, compensated for the gap. A linear correction was also supposed based on the correlation between the NSB levels measured by the two instruments; the mean squared error after the correction was 0.03 mag arcsec−2.

International high-frequency arbitrage for cross-listed stocks

We explore high-frequency arbitrage activities on international cross-listed stocks and develop a methodology to study the effect of information latency in high-frequency trading. We derive statistical arbitrage bounds for a mean-reverting synthetic instrument engineered from cross-listed stock prices, and we propose a new strategy that takes advantage of price deviations outside these bounds. Market frictions such as trade costs, inventory control, and arbitrage risks are considered. The strategy is tested with cross-listed stocks involving three exchanges in Canada and the United States in 2019. The annual net profit with the limit order strategy is around US$6 million, whereas the market order version is not profitable because of the great interconnectedness between exchanges in our data.

Reinforcement learning design framework for nacre-like structures optimized for pre-existing crack resistance

Nacre is known for its uniquely high toughness and lightweight capabilities. Its unique structure is composed of soft nacre proteins and stiff calcium carbonates, allowing it to deflect cracks that expand in straight lines to increase energy dissipation. However, nacre microstructures are challenging to mimic due to the intractable number of combinations in the design space. We thus propose a reinforcement learning (RL) framework to efficiently design a high-toughness nacre-like structure. By designing local structures at the crack tip, we incorporated reinforcement learning with finite element to optimize the structure by replacing the soft and stiff materials in the design space. Starting from the initial unit cell, where the majority of the unit cell consists of soft materials, our method gradually improves the cell by arranging stiff and soft materials on the unit cell to achieve higher toughness. The optimized designs exhibit crack-insensitive behavior and excellent crack resistance when subjected to finite element simulation and experimental testing. This design framework can be used in synthetic instruments that require rapid construction rearrangements such as biomaterials and unexposed substructures, increasing their mechanical performance.

Estimating dynamic spatial panel data models with endogenous regressors using synthetic instruments

The paper applies synthetic instruments, initially developed for cross-sectional regression, to estimate dynamic spatial panel data models. These have two main advantages. First, instruments correlated with endogenous variables and yet independent of the errors are difficult to find. Not only are synthetic instruments normally exogenous, but they are usually strongly correlated with endogenous variables, and thus help to avoid the problem of weak instruments. Secondly, they help to reduce instrumental variables proliferation, which is a common result of standard methods of avoiding endogeneity bias. As demonstrated by Monte Carlo simulation, instrument proliferation causes bias in the Sargan–Hansen J test statistic, which is an important indicator of instrument validity and hence estimation consistency. It is also associated with a downward bias in parameter standard error estimates. The paper shows the results of applying synthetic instruments across a variety of different specifications and data generating processes, and it illustrates the method with real data leading to more reliable inference of causal impacts on the level of employment across London districts.

Market Manipulation around Seasoned Equity Offerings: Evidence Prior to the Global Financial Crisis of 2007–2009

Since the adoption of the SEC’s Rule 10b-21 in 1988, many researchers have been concerned over the effectiveness of short sales constraints in preventing manipulative trading in the derivatives market. We analyze whether options can be used as synthetic short sale instruments to manipulate stock prices before a seasoned equity offer. Due to the existence of strict short sales constraints in the equity market and market makers’ anticipation of manipulative trading, it would be very costly for a manipulator to drive stock prices down artificially either by short selling in the equity market or by using synthetic short sales in the options market. Using a sample of 237 firms that issued SEOs on the NYSE and had options listed on any U.S. options exchange from April 2002 to December 2004, we show that potential manipulators in the options market tend to use put options as a trading vehicle during the SEO’s pre-offer period. The results of our empirical tests support the predictions of our model.

Cu-Modified Magnetic Creatine as an Efficient Catalyst for Regioselective Preparation of 1,2,3-Triazoles Derivatives

The present study focuses on Fe3O4@Creatine@Cu catalyzed one three-component reaction called “click reaction” to synthesize 1,2,3-triazoles. Therefore, a mild and green synthesis was developed for 1,3-dipolar cycloaddition reactions of several various azides and alkynes. This cycloaddition is a strong synthetic instrument in the creation of a heterocyclic ring, with wide usages in various fields. Creatine derivative functional groups were linked to the magnetic nanostructure as an efficient ligand by high amounts of oxygen and nitrogen to improve the catalyst action. Afterwards, Cu(II) ions were attached to the surface of the magnetic creatine structure to gain the last catalyst; then, this catalyst was characterized using some analysis methods, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and energy-dispersive X-ray analysis (EDX). The recycled catalyst was performed five times without any considerable decrease in catalytic magnetic properties and efficiency. Significant advantages of this procedure include high speed, mild condition, reusability, high yield, and affordability which make this method attractive.

A Better Legal Definition of Gambling: With Applications to Synthetic Financial Instruments and Cryptocurrency

A Better Legal Definition of Gambling: With Applications to Synthetic Financial Instruments and Cryptocurrency

The Science of Tooling – Design Framework for Digital Tools in Support of Socio-Spatial City Analysis

In the context of the digital transformation of cities, the application of data-driven tools has become a common practice in urban studies and metropolitan research. Beyond their appropriate utilisation, their targeted design poses challenges as well. Unlike established practices in the engineering and design domains, there are only few processes established that support the targeted creation of analytical or synthetic instruments for the processing of urban data. Therefore the paper outlines a framework for a design science of digital tools that address the socio-spatial complexities of urban systems. It does so by discussing four key aspects whose investigation and integration is requisite for devising instruments applicable for urban research, planning, and decision making. The outlined methodology provides a systematic approach for the design of digital city tools as well as an educational blueprint to enable next-generation digital city scientists to understand the structure of such instruments as well as their implications for practical work. The consolidation of digital tooling thus forms a central component in data-driven urban planning and analysis i.e. Digital City Science.

When the Going Gets Tough … the Effect of Economic Reform Programmes on National Well-Being

Well-being is an essential human need and has social, psychological and economic benefits. Consequently, social scientists and economists, in particular, want to know whether economic reform can lead to increased (and sustainable) happiness. To answer this question, we applied a new approach—investigating the effect of economic reform programmes on national well-being for 154 countries between 2005 and 2018. As the dependent variable, we employed national subjective well-being scores based on people’s evaluation of their satisfaction with life. International Monetary Fund economic reform programmes provided a sufficiently long time–series and global presence for the main independent variable. We used a treatment effect model and fixed-effects instrumental variable panel with the novel approach of synthetic instruments, to address selection bias generated by the non-random selection of countries into International Monetary Fund programme participation, also controlling for unobservable characteristics influencing both International Monetary Fund participation and national well-being. Irrespective of the approach used, empirical findings show that economic reform programmes lead to increased national well-being globally, both in the short-term and the long-term. The results do not imply that International Monetary Fund arrangements should be used as policy tools to increase national well-being. They empirically confirm our argument that improvements in national economies sustaining increased well-being require intentional effort and engagement.

On Synthetic Instrument Response Functions of Time-Correlated Single-Photon Counting Based Fluorescence Lifetime Imaging Analysis

Time-correlated single-photon counting (TCSPC) has been the gold standard for fluorescence lifetime imaging (FLIM) techniques due to its high signal-to-noize ratio and high temporal resolution. The sensor system's temporal instrument response function (IRF) should be considered in the deconvolution procedure to extract the real fluorescence decay to compensate for the distortion on measured decays contributed by the system imperfections. However, to measure the instrument response function is not trivial, and the measurement setup is different from measuring the real fluorescence. On the other hand, automatic synthetic IRFs can be directly derived from the recorded decay profiles and provide appropriate accuracy. This paper proposed and examined a synthetic IRF strategy. Compared with traditional automatic synthetic IRFs, the new proposed automatic synthetic IRF shows a broader dynamic range and better accuracy. To evaluate its performance, we examined simulated data using nonlinear least square deconvolution based on both the Levenberg-Marquardt algorithm and the Laguerre expansion method for bi-exponential fluorescence decays. Furthermore, experimental FLIM data of cells were also analyzed using the proposed synthetic IRF. The results from both the simulated data and experimental FLIM data show that the proposed synthetic IRF has a better performance compared to traditional synthetic IRFs. Our work provides a faster and precise method to obtain IRF, which may find various FLIM-based applications. We also reported in which conditions a measured or a synthesized IRF can be applied.

Ultrasound-Assisted Synthesis and Crystal Structure of Novel 2D Cd (II) Metal–Organic Coordination Polymer with Nitrite End Stop Ligand as a Precursor for Preparation of CdO Nanoparticles

In the present research, a sonochemical approach was applied to prepare new cadmium(II) coordination 2D polymer, [Cd(L)(NO2)2]n (L = 1,2-bis(1-(pyridin-3-yl)ethylidene)hydrazine) and structurally characterized with various spectroscopic techniques including XRD, elemental analysis, SEM, and IR spectroscopy. The coordination number of cadmium (II) ions is seven (CdN2O5) by two nitrogen atoms from two organic Schiff base ligand and five oxygen of nitrite anions. The 2D sheet structures ended by nitrite anions and the nitrite anion displayed the end-stop role. The comprehensive system showed a three-dimensional structure with several weak interactions. The high-intensity ultrasound is regarded as an easy, environmentally-friendly, and flexible synthetic instrument for the compounds of coordination. CdO NPs was obtained by thermolysing 1 at 180 °C with oleic acid (as a surfactant). Further, the size and morphology of the produced CdO nanoparticles were investigated through SEM.

A proposal of a financial knowledge scale based on item response theory

The evaluation of financial knowledge is still a controversial subject in the literature, and this work seeks to advance by proposing instruments for this evaluation. Based on the related literature, twenty-four questions were adapted in the initial instrument. Using Item Response Theory, a synthetic instrument was developed, with twelve questions that evaluate three levels of items: basic, intermediate and advanced. From the skill and anchor items scale, two smaller scales of nine and seven items were also derived for financial knowledge assessment. The scales proposed in this study innovate by differing from those commonly used in the literature, by considering not only the percentage of correct answers but also the parameters of the item that the individual answers correctly. The three scales have items from different levels of knowledge, allowing researchers, educators, and policymakers to choose which is the most appropriate to their objectives.

High-speed I/O capabilities added to military automatic test equipment (ATE) using synthetic instruments

High-speed testing of digital transmission necessitates a functional test, which is typically the test performed by automatic test equipment (ATE) on military and avionics units under test (UUTs). Older military ATEs, and indeed most modern day ATEs, are not equipped with test instruments for high-speed data transmission. Typically, such high-speed test instruments are designed for signal characterizations in design verification tests, which require human interpretations. The primary purpose of military ATE is to allow non-technical soldiers or sailors to comprehensively test and diagnose all types of electronics and to derive very specific repair instructions. We introduce synthetic instruments (SIs) and show how they offer a feasible option for traditional ATEs while they are also able to test high-speed unit under test (UUT) signals. Rather than replace military ATEs, the high-speed SI solution can be integrated into existing ATEs, even legacy ATEs. The clear benefit of this approach is the extension of ATE useful life and the capability to test present and even future circuit types. It also improves the performance of military ATEs by allowing them to test multi-Gbps signals. High-speed I/O, such as the USB 3.0 that operates at 5 Gbps is discussed. (Although USB 3.0 was recently renamed as USB 3.2 Gen 1, for consistency in this article, we use the traditional term USB 3.0.) The example utilizes a special-purpose USB 3.0 SI that responds to commands in the test program set (TPS) developed by test engineers. The same USB 3.0 SI, including the test commands, can then be reused on other ATEs and UUTs with the same bus. This can be an industry-wide game changer when SIs are developed for other I/O buses and applications. Utilizing SIs reduces TPS development costs and ATE expenditures, while improving TPS development times and effort.

Smart Supra- and Macro-Molecular Tools for Biomedical Applications.

Stimuli-responsive, “smart” polymeric materials used in the biomedical field function in a bio-mimicking manner by providing a non-linear response to triggers coming from a physiological microenvironment or other external source. They are built based on various chemical, physical, and biological tools that enable pH and/or temperature-stimulated changes in structural or physicochemical attributes, like shape, volume, solubility, supramolecular arrangement, and others. This review touches on some particular developments on the topic of stimuli-sensitive molecular tools for biomedical applications. Design and mechanistic details are provided concerning the smart synthetic instruments that are employed to prepare supra- and macro-molecular architectures with specific responses to external stimuli. Five major themes are approached: (i) temperature- and pH-responsive systems for controlled drug delivery; (ii) glycodynameric hydrogels for drug delivery; (iii) polymeric non-viral vectors for gene delivery; (iv) metallic nanoconjugates for biomedical applications; and, (v) smart organic tools for biomedical imaging.

Simulated training model of ureteropyelic anastomosis in laparoscopic pyeloplasty.

Purpose:To develop a model for simulated training of ureteropyelic anastomosis in laparoscopicpyeloplasty.Methods:Longitudinal and experimental study, with 16 participants. A synthetic instrument was produced to simulate the renal pelvis and the proximal portion of the ureter positioned on a platform within laparoscopic simulators, thereby resulting in the realistic simulation of the ureteropelvic anastomosis. A step-by-step guide was also developed for the accomplishment of the ureteropelvic anastomosis training model.Results:In the evaluation of all participants’ suture training, a decrease was found in the time needed to perform the anastomosis, with a median of 17.83 min in the 1st step and 14.21 min in the last one (p = 0.01). Regarding the knots, in the 1st step, 5% of them were considered firm, with an evolution to 30% in the last step (p = 0.011).Conclusion:We noticed improvement in the ability to perform the ureteropelvic anastomosis by participants with no experience with it. Therefore, even unexperienced participants can improve their skills with this training. Moreover, we observed the effectiveness of the model use, confirmed by the participants’ opinion and its validation by expert surgeons.

Synthetic Instrumental Variables

This paper presents a new method for synthesizing instrumental variables using only the dependent and endogenous explanatory variables of the regression model. We show that a valid instruments can be spanned using the dependent and endogenous variables. Then based on this rationale, we construct an estimator that uses moment conditions stemming from the validity of such synthetic instruments. We demonstrate the consistency of the newly-developed estimator using synthetic variables. A computational algorithm is developed using the moments conditions stemming from the consistency of the estimator. One can use this synthetic instrumental variables method as an alternative to traditional external instruments methods.

A pairwise local correlation model

We develop a local correlation model that uses a given correlation matrix and a generic function g.t ; mi ; mj / to compute the local correlation between any asset–asset pair .i; j / of a basket of underlyings. The arguments mi , mj are spot moneynesses. The generic function is calibrated to fit the implied volatilities of an equity index such as the DAX or EURO STOXX 50. The advantage of this approach is that we do not need to simulate the complete index basket when pricing options on a (usually small) subset of this index. The approach does not suffer from the so-called chewing gum effect of correlation models, where the local correlation depends on just the index value. We first show how to calibrate the generic function for each time step with constraints on the positive definiteness of the resulting correlation matrixes and the smoothness of g to allow for stable evaluation. We then present numerical experiments that show the impact on prices and deltas for synthetic autocallable instruments.

Digital radio frequency memory synthetic instrument enhancing US navy automated test equipment mission

This research project aims to expand the capability of a current US Navy Automated Test Equipment (ATE) family of testers known as the Consolidated Automated Support System (CASS). Industry research is now focused on breaking the historical construct of test equipment. Advances in the field of Synthetic Instruments have opened the door to test avionics in new ways. Every year new capabilities are developed using core hardware and increasingly capable software modules to create complex waveforms. This research creates a Digital Radio Frequency Memory (DRFM) Synthetic Instrument that can be programmed to perform a wide array of low latency Radio Frequency (RF) tests. Synthetic Instruments are defined as a concatenation of hardware and software modules used in combination to emulate a traditional piece of electronic instrumentation. This Synthetic Instrument couples high speed Analog-to-Digital Converters (ADC) to high speed Digital-to-Analog Converters (DAC) with Field Programmable Gate Arrays (FPGA) in between for digital signal processing. An RF front end is used to down convert the RF to baseband where it is sampled, modified, and up converted back to RF. The FPGA performs Digital Signal Processing (DSP) on the signal to achieve the desired output.